The sequence of designing the technological process of manufacturing a part. The sequence of technological design. Rules for the design of operational sketches
The initial data for the design of the technological process are:
a) working drawing of the workpiece to be processed, absolutely necessary technical conditions;
b) drawing of the assembly unit, which includes the workpiece to be processed;
c) production program for the release of parts;
d) data on equipment in the form of passports of machines and a plan of their location in the workshop and a catalog of manufactured equipment.
In addition, it is necessary to have reference materials: standards for operating allowances and tolerances, catalogs for cutting, measuring and auxiliary tools, standards for the assortment of materials, standards for cutting conditions, standards for auxiliary, preparatory and final time and time for servicing the workplace. A large program allows you to use high-performance equipment, multi-spindle and modular machines, semi-automatic and automatic machines, to automate processes,
The technological process is developed in a certain sequence (GOST 14.301-73).
1. Determine the type of production, production cycle or batch size, type of workpiece.
2. Establish a rational sequence of processing - a technological route.
3. Select machines for individual operations.
4. Determine the method of installation (basing) and fixing the workpiece at each operation and specify the order of operations.
5. The operation is divided into transitions and moves, interoperative allowances and tolerances are established.
6. Determine the dimensions of the workpiece.
7. Select fixtures and outline the concepts of special fixtures.
8. Select the type and size of the tool and develop constructive sketches of special tools.
9. Set cutting conditions for all transitions.
10 .. Carry out technical rationing and establish a profession and job category.
11. Produce comparative economic calculationsif several possible processing options are outlined.
12. Draw up the documentation of technological processes of mechanical processing.
13. Develop the organization of production sites, including their layout and intrashop transport.
The development of technological processes is one of the most important stages in the preparation of production, since product quality, labor intensity and efficiency of production, as well as the speed of production development, largely depend on it. When developing technological processes, one should strive to reduce the number of operations, since this reduces the need for machines, workers, production area, interoperational transportation and reduces the cost of manufacturing a part. The productivity of the operation is increased by reducing the number of transitions through the use of multi-spindle adjustments; the minimum number of strokes reduces the main time due to the use of precision workpieces
1.8.2. Concentration and differentiation of operations
The design of technological processes for cutting can be carried out by methods of concentration and differentiation. The first method is characterized by the combination of several technological transitions into one complex operation performed on one machine. The concentration of operations is carried out in two ways: by simultaneous processing of several surfaces with a set of tools, for example, processing on a multi-cutter lathe or on a multi-spindle drilling machine, and sequential processing of several surfaces on one machine, for example, on a turret. The concentration of operations reduces the labor intensity of processing, reduces the number of machines and production area, but at the same time increases the need for highly skilled fitters and requires the use of more complex machines. The use of multi-tool machines is economical with a large production of parts.
The method of differentiation of operations is characterized by the division of the technological process of cutting into simple operations performed on a large number of simple machines (used in large-scale production with a lack of special equipment and the absence of skilled workers). This method allows you to quickly transfer the work of a workshop or department to the production of a new or changed object, since the reconfiguration of simple machines is easier than reconfiguring complex machines with a large concentration of individual technological transitions. The division of the process into several operations, caused by the requirement of high accuracy or low surface roughness, should not be considered a differentiation. There are a number of transitions that are impractical to combine with others on the same machine, as this can lead to a decrease in accuracy and an increase in surface roughness. In engineering plants, both principles are often combined. For example, when processing crankshafts, along with the use of special machines for processing the main or connecting rod journals, machines are used that perform one operation - preliminary or final grinding of the main or connecting rod journals.
1.8.3. Basics of building a route technological process
When processing a workpiece, as a rule, the main allowance is removed (roughing), a given shape size and relative position of the workpiece surfaces, a given roughness and quality of the surface layer (finishing and hardening) are obtained. Processing methods, equipment, tools and fixtures do not allow to complete all the tasks in one stroke of the cutting tool. During roughing, the acting forces and cutting work are especially large; workpieces get very hot. Under these conditions, it is impossible to obtain the exact dimensions of the workpiece. Therefore, the sequence of operations must be assigned based on some considerations.
1. Roughing removes the largest metal layers. This allows you to immediately identify defects in the workpiece. When the surface layers are removed, the workpiece is freed from internal stresses that cause deformations. Roughing requires significant clamping forces that can affect the accuracy of the finished surface if a portion of the workpiece is to be roughed after finishing. Such unfavorable conditions are created when machining large surfaces of shaped blanks. For small workpieces, roughing and finishing are performed in one operation. One should not be afraid of a redistribution of internal stresses when processing individual small surfaces in shaped workpieces.
2. Finishing operations must be performed at the end of the workpiece processing, so
how this reduces the possibility of damage to already processed
surfaces.
3. When determining the sequence of roughing and finishing operations, it should be borne in mind that their combination on the same machines leads todecrease in processing accuracy due to increased wear of the machine in roughing operations.
4. First of all, the surfaces should be processed, when removing the allowance from which the rigidity of the workpiece decreases to the least degree; for example, when machining stepped shafts, large diameter steps are first processed, and then smaller diameter steps
5. Surfaces with the same relative positioning accuracy must be machined in one setting and one position.
6. When using automatic lines in the technological process, the method of concentrating the operations of the technological process should be applied, that is, the simultaneous execution of a large number of transitions at each operation, and combined tools should be used (step countersink, reamer, etc.). To obtain an automatic line of short length, the machines are placed on both sides of the roller table or in a zigzag manner.
Cutting operations must be linked with thermal ones, assigning separate operations after heat treatment operations that increase the mechanical properties of the metal (carburizing, hardening). The interoperative allowances depend on the type of heat treatment. They need to be increased in order to provide smaller deviations from the shape of the geometric surface disturbed by deformations caused by heat treatment.
1.8.4 Equipment selection
The choice of the machine is one of the important tasks in the design of the technological process of cutting. You can always find the right machine for any operation. Exceptions are some operations in mass production, for which it is economically feasible to manufacture special machines. When designing technological processes of serial production, where, along with special ones, universal machines are also used, the latter are selected according to the following indicators:
1) type of processing - turning, milling, drilling, etc .;
2) accuracy and rigidity of the machine;
3) overall dimensions of the machine (height and distance between centers, table dimensions);
4) machine power, feed spindle speed, etc .;
5) the price of the machine.
In serial production on one machine, as a rule, several different operations are performed, therefore, the selected machine must meet the technological requirements of all planned treatments. In mass production, each machine is designed to perform one operation and must satisfy not only all the requirements of this processing, but also provide a given productivity. When choosing a machine for mass production, in addition to the above indicators, it is necessary to take into account the correspondence of the productivity of the machine to the cycle of production of parts processed on this machine. The classification of machine tools according to technological characteristics was proposed by prof. A.I. Kashirin. According to this classification, machine tools are divided into general-purpose or general-purpose (universal), high-performance, specialized, special machines. General purpose or general purpose machines: designed for processing workpieces in batch and one-off production. High-performance machines have limited technological capabilities in comparison with universal ones. They are more powerful and stiffer than the machines of the first group, thanks to which they can be used for machining at higher cutting conditions. These include multi-cutter turning machines, cylindrical grinding machines operating by the cross feed method, centerless grinding, some longitudinal milling, automatic lathes and semi-automatic machines. These machines are designed for large series and mass production and are also used in series production. Specialized machines can be adapted to perform specific operation... Often, machines of this group are obtained by installing additional spindles, heads and other assemblies on high-performance machines. Special machines are designed and manufactured according to specialorder and are intended to perform a specific operation. The design and manufacture of machines in this group is usually expensive. Therefore, such machines are used only in mass production if their economic efficiency is proven.
Automatic machine lines are groups of automatic machines installed in the order of the technological process and interconnected by transporting devices. A workpiece to be processed is placed on the conveyor at the beginning of the line, or many workpieces are loaded into the hopper at once, and then they are automatically transferred from the machine to the machine. Along with the creation of automatic lines on the basis of the existing equipment, automatic lines are designed and built from special machines.
With large programs for the production of parts, modular machines are widely used. The Experimental Research Institute of Metal-Cutting Machine Tools (ENIMS) has developed a classifier for metal-cutting machine tools.
1.8.5 Tool selection
The design and dimensions for a given operation are predetermined by the type of processing, the dimensions of the processed surface, the properties of the workpiece material, the required processing accuracy and the roughness of the processed surface. Cutting tools are mainly made of VK8, T5K10, TI5K6 hard alloys, T30K4, T60K6and others, high-speed steels R6M5, P9K10,carbon tool steels U10A, U12A, etc. Tools; equipped with plates of hard alloys VK8 and VK6M, are used in the processing of workpieces from cast iron. For rough processing of steel workpieces, a tool with T5K10 alloy plates is used, and for finishing, a tool with TI5K6 alloy plates. Carbide tools are recommended to be used to achieve high productivity, the smallest roughness of the machined surface and when machining workpieces made of metals of high hardness.
High speed steels are used for the manufacture of tools operating at relatively high cutting speeds and complex tools
Carbon tool steels are used to manufacture hand tools (taps, dies, etc.).
1.8.6 Rules for drawing up operational sketches
The rules for recording technological operations and cutting transitions are established by GOST 3.1702-79.
The name of the cutting operation should reflect the type used technological equipment and written as an adjective in the nominative case, for example: gear grinding, honing, planing, drilling-centering, slot-rolling, etc.
milling, grinding, tumbling, installing, removing, countersinking, honing, etc.
Example1. Full record: “Drill 8 through holes followed by chamfering; maintaining d \u003d 12 +0.5 \\ d-90 ± 0.08, 90 ° ± 30 "and 1.6 * 45 °, according to the drawing."
2. Abbreviated notation: "Drill 8 holes, keeping sizes 1, 2, 3.
The establishment of a complete or abbreviated record of the content of a technological operation for each specific case is determined by the developer of the documents. Auxiliary transitions should be recorded in accordance with the rules for technological transitions.
When filling out documents in a handwritten way - instead of the symbol d, you should use the Ǿ sign and do not indicate the designations: length, width, chamfer. For example: “Rebore the surface, keeping the dimensions Ǿ 12.
for technological transitions - roll, crash, roll, engrave, finish, chisel, round, sharpen, countersink, roll, cut, roll in, cut, trim, polish, grind, run in, stretch, unfold, flare, roll, drill, bore, drill, plan, superfinish, sharpen, honing, grind, counterbore, center, mill;
for auxiliary passages - align, secure, adjust, reinstall, reinstall and secure, move, tighten, check, lubricate, remove, install, install and align, install and secure.
When developing technological sketches for an operand or individual technological transitions, it is necessary to fulfill all the requirements for graphic documents.
A technological sketch is developed for each operation in serial and mass production. The technological sketch is the initial data for detailed description operations on transitions or positions. The technological sketch indicates all the necessary data for high-quality processing of the part; the required dimensions of the machined elements of the part with deviations are indicated, as well as the necessary reference dimensions that will be used in the process of determining the cutting conditions and time norms for technological transitions to the operation.
For each processed element of the workpiece, the surface roughness is set and the roughness symbol is indicated depending on the processing height and the degree of accuracy. Identical surface roughness values \u200b\u200bare grouped and taken out to the upper right corner of the sketch.
It is necessary to indicate on the technological sketch legend supports, clamps on the base surfaces of the part according to GOST 3.1107-81 "Supports, clamps and mounting devices. Graphic symbols ".
The required number of images (views, sections, sections and leaders) on the sketch is set from the conditions for ensuring the visibility and clarity of the image of the processed surfaces of the part. The surfaces to be processed on the sketch should be outlined with a solid line equal to 2S ... 3S in accordance with GOST 2.303-68,
It is allowed to conditionally number all surfaces to be treated with Arabic numerals in the technological sequence and connect them to the dimension line. Surface numbers are enclosed with a circle sign with a diameter of 6 - 8 mm.
Technological sketches for an operation or transitions are made without scale, however, the sketches should be done accurately and clearly. Symbols used in technological sketches must comply with established standards. Non-standard designations must be specified in the notes to this sketch.
59. The general sequence of designing the assembly process. Initial data for the development of the assembly process.
General assembly process design sequence
Basic design stages
Obtaining initial data for design;
Analysis technical requirements, identification of technological problems, the choice of methods and means of control;
Calculation of the release cycle and establishment of the method of work (in-line, non-flow);
The choice of the organizational form of the assembly (stationary, mobile);
Technological analysis of assembly drawings and working drawings from the point of view of manufacturability of product design;
Choice of a method to ensure a given accuracy
Choice of route technology;
Construction of operations;
Selection and development of service stations required for the implementation of the technical process;
Technical regulation of assembly work;
Calculation of technical and economic indicators of the assembly process and evaluation of options;
Registration technological documentation.
The initial data include:
Assembly drawings with all technical requirements;
Working drawings of parts;
Specifications for assembly units and the product as a whole;
Technical conditions for product acceptance;
Release program;
A sample of the assembled product.
2) Having the initial data, the technologist must study the service purpose of the machine and analyze its design. You need to make sure:
In the possibility of connecting mating parts;
In the absence of obstacles in the implementation of such connections;
In the possibility of disassembly;
In the absence of obstacles to the installation of assembly units.
Technical requirements, as a rule, boil down to compliance with the accuracy of position, rotation, linear movement of the components relative to each other. These requirements are ensured through the accuracy of the relative position of the assembled parts, regulated by the requirements of parallelism, perpendicularity, alignment, symmetry and runout. After making sure that the assembly is possible, it is necessary to establish methods and means to achieve the required accuracy and control, the main accuracy parameters.
If it is impossible to ensure the accuracy requirements and their control, it is necessary to adjust the design together with the designer to create a more technologically advanced design.
When formulating technological tasks, the following are identified:
Basic accuracy characteristics;
Mutual position of parts corresponding to the worst accuracy indicators;
For landings with a gap, the possible positions of the links are analyzed and their positions are determined that most favorably affect the accuracy of the product;
Methods of compensation of errors inherent in the design are determined, methods of control of accuracy parameters are determined and schemes for their control are drawn up.
3) The method of work depends on the annual program; the degree of differentiation of the technical process is determined after comparing the average duration of assembly operations with the production cycle, the expected load factor is calculated:
where τ is the release cycle;
T pcs.av - average piece time, determined according to the consolidated standards.
If K is closer to 1, then the assembly is built on the basis of the flow method and one operation is assigned to each workplace.
It is usually considered that the flow method is advisable at K\u003e 0.7 ... 0.75.
If the production cycle significantly exceeds the average piece time, then several operations are assigned to each workplace and the size of the production batch is estimated.
With a small production program and complex products, the batch size corresponds to a three-month program, i.e. launch once a quarter.
For products medium difficulty launch once a month - monthly program.
For simple products and large production programs, batch size is a two week program.
4) The choice of organizational form is determined by the annual program, the variety of assembled products, their technological complexity, dimensions and weight.
5) Analysis of manufacturability.
6) The choice of the method of ensuring accuracy (5 methods, complete interchangeability ...).
7) Choice of route technology. Products are divided into assembly units, the appropriate degree of differentiation of the assembly process is determined, and the sequence for connecting all assembly units and product parts is established. The following principles are taken into account:
Feasibility of separating an assembly unit (both constructive and technological).
An assembly unit should not contain too many component parts. It should not have too few components due to the complication of completing the overall assembly.
If, as a result of the assembly of an assembly unit, its testing or running-in or fitting work is required, then such an assembly must be taken out of the general assembly.
After assembly on the product, assembly units should not be disassembled.
The complexity of the assembly of all assembly units should be approximately the same.
After that, a technological assembly system is drawn up.
The main assembly operations are identified according to the accepted technological schemes of the nodal and general assembly. Operations are distinguished so that work that is homogeneous in nature is performed at the workplace, which must be technologically completed. After that, a technical process is drawn up, the degree of detail of which depends on the type of production.
In single and small-scale production, they are limited to the development of a route technological process, which represents a list and sequence of assembly operations.
Route description requires a highly skilled worker.
The operational description is used in operational technical processes developed for batch and mass production conditions. In this case, operations are developed in as much detail as possible with an indication of the content and sequence of transitions performed and with information on technological modes.
The route-operational description method with such a technical process is partly performed according to the operational description (for complex operations). It is used in the conditions of small-scale, medium-scale and large-scale production.
8) Design of technological assembly operations (for conditions of serial and mass production).
In the operational assembly process, when identifying the order and sequence of operations, take into account:
The ability to combine an operation with another operation or with several operations by dividing this operation into parts;
Possibility of a more rational sequence of operations;
The possibility of combining a technological operation with a control one;
Simplification of a complex operation by separating its finished part into a separate operation;
The ability to perform assembly operations requiring fit in the machine shop.
CLASSIFICATION OF TECHNOLOGIES
INDUSTRIAL TECHNOLOGIES AND TECHNICAL PROGRESS
INTRODUCTION
INDUSTRIAL TECHNOLOGIES AND INNOVATIONS
At present, the most important problems of the Russian national economy are: improving the quality characteristics of manufactured industrial products, reducing its cost and increasing labor productivity, significantly expanding the scale of technical re-equipment of existing enterprises, equipping them with new highly effective equipment, introducing progressive technology and modern management methods.
Reducing material consumption, increasing the efficiency of the use of material resources, the use of advanced materials is one of the most urgent tasks of industrial production. The creation and development of new materials with high performance characteristics and stability of physical and mechanical properties over time will allow the development of fundamentally new samples of consumer goods and high demand, which determine the economic situation of the relevant industry and the country as a whole.
The introduction of high-performance and precision equipment, qualitatively new technological processes based on an innovative principle is the main way to increase the industrial capacity of modern production. Such equipment and processes should be widely used in the manufacture of science-intensive products that meet the best world standards and are in high demand on the world market.
There are plenty of concepts and forecasts regarding the future of Russia in the 21st century. The approaches and opinions in them sound very different. Some of the Western countries share the point of view expressed in one of his speeches by former British Prime Minister John Major. Speaking about the future of Russia, he predicted the role of a storehouse of resources for the needs of the West, adding that 40-50 million of the population would be enough for this. If we accept the logic of such a forecast, then the financial elite, generated by transnational corporations, which, and rules the world, have actually already made a choice for Russia - a “stoker” and a “hallway”. But then this very elite will have to ascribe a number of rather paradoxical qualities - short-sightedness, imprudence, a tendency to generate hotbeds of tension. By provoking instability, stinging the pride of a still nuclear power, the global financial elite, if any, looks too desperate and insidious.
An alternative scenario is based on the so-called economic growth strategy. It is based on a stake on enhancing the competitive advantages of the Russian economy. There are eight of them:
1. The level of education together with an orientation towards collectivism;
2. Natural resources;
3. Territory and capacious domestic market;
4. Cheap and qualified enough work force;
5. Scientific and industrial potential;
6. Science schools and competitive technologies;
7. Free production facilities,
8. Export experience high-tech products and industrial cooperation.
To realize all these advantages, of course, a system of economic and administrative measures must be thought out. Calculations already in the medium term promise sustainable economic growth of at least 7% per year, an overall increase in investment by at least 15% per year, and in high-tech industry and new technologies - up to 30%. Inflation will also be capped at 30% per annum ...
Many experts place their main hopes on the realization of the country's scientific and industrial potential. Russia, which has 12% of the world's scientists, actually has no other serious alternative. For raw materials, even with 28% of the world's reserves, it is impossible to achieve an acceptable economic recovery. According to forecasts, its consumption by 2015 will increase by only 2 times, while we are already lagging behind developed countries by about 10 times in terms of gross domestic product per capita (GDP). But the volume of the world market for high technology products today is 2 trillion. 500 billion dollars (Russia's share is 0.3%). By 2015, it will reach about $ 4 trillion. dollars. Even a tenth of this amount is about an order of magnitude higher than the potential Russian oil and gas exports. On the other hand, the chances of promoting the innovation process on a national scale, letting inflation go up to 30% per year, seem problematic. It is known from world experience (Argentina) that this is the maximum level, above which inflation becomes the main obstacle to economic growth.
For all major indicators, the country has the same industrial infrastructure as the Western countries. And only in the development of the technological environment (quality assurance systems, standards, automation of development, computerization of production, etc.) we are very far behind them. The level of development of technological infrastructure is a kind of dividing line between industrial and post-industrial countries. This is what Russia must overcome.
How seriously are we lagging behind in this regard? The numbers speak for themselves. In 2008, everyone employed in the Russian economy contributed $ 16.1 thousand to the country's GDP. Let's compare: in South Africa this figure was 38.1 thousand, in France - 59.4 thousand, in the USA - 74.6 thousand, in Luxembourg - 110 thousand. Why it happens? Where does this difference come from? On the one hand, enterprises in developed countries produce higher quality and more complex products than in Russia. It sells for more and has much higher added value. On the other hand, the much more advanced technical equipment of Western enterprises ensures greater labor efficiency and allows the production of a larger amount of finished products.
For example, let's take two automobile companies that employ an equal number of employees: AvtoVAZ - 106 thousand people and BMW - 107 thousand.AutoVAZ produces an average of 734 thousand cars a year with a total value of $ 6.1 billion, BMW - 1.54 million cars by 78.9 billion. That is, in "natural" terms, the productivity at AvtoVAZ is 2 times less, and in value terms - more than 13 times.
The analysis of the world market shows that the production of high technology products is provided by only about 50 macro technologies (macro technology is a combination of knowledge and production capabilities for the release of specific products on the world market - aircraft, reactors, ships, materials, computer programs, etc.). Seven most developed countries, possessing 46 macro technologies, hold 80% of this market. The United States annually receives about $ 700 billion from the export of science-intensive products, Germany - 530, Japan - 400. Forecast for 16 macro-technologies has already been made (see table).
Macro technology market (in billions of dollars)
2010 2015
Aviation technologies 18-22 28
Space technologies 4 8
Nuclear technology 6 10
Shipbuilding 4 10
Automotive 2 6-8
Transport engineering 4 8-12
Chemical engineering 3 8-10
Special metallurgy. Special chemistry.
New materials 12 14-18
Oil production and processing technology 8 14-22
Gas production and transportation technology 7 21-28
Power engineering 4 12-14
Industrial technology
equipment. Machine-tool building 3 8-10
Micro- and radioelectronic technologies 4 7-9
Computer and information
technology 4.6 7.8
Communication 3.8 12
Biotechnology 6 10
Total 94-98 144-180
There is fierce competition in the world market. So, over the past 7-10 years, the United States has lost 8 macro technologies and, accordingly, their markets. As a result, we got a deficit in effective demand of 200 billion dollars. The reason for this is that about 15 years ago, the Europeans formed a common program with the aim of winning a share of the market from the United States and Japan. Technologies were rebuilt for it, basic research, industry has been restructured.
Now a similar targeted attack is being undertaken by a European aviation consortium. Its experts identified the possibility of winning 25% of the heavy aircraft market ($ 300 billion). A corresponding international program was formed. Even American competitors were drawn into it by buying up their firms. Russia was offered to create a joint science Center, signed contracts with our factories. In general, 20% of the total volume of the program became Russian. In a word, the history of this major transnational project clearly testifies: in the distribution of orders, first of all, business expediency is decisive.
According to our experts, for the market of 10-15 macro technologies out of those 50 that determine the potential of developed countries, Russia is quite capable of competing. The choice of macrotechnological priorities in our country should be carried out on a principle that is completely new for us. Supporting dozens of priority scientific and technical programs along the entire front of conceivable research is completely unpromising. Even the richest country cannot afford this today. In order to assign a particular macrotechnology the priority status for our country, it is proposed to compare the costs of forming a knowledge base on it (complete or sufficient) and the possible effect of the sale of competitive products created on its basis.
Federal target programs are formed for each priority macrotechnology. The government places orders for them on a competitive basis with institutes and design bureaus. As a result, the industry receives a related set of tasks for the design of integral technological systems. (By the way, according to a similar scheme, Russia, having adopted the target program "Fighter-90s" 15 years ago, conquered the market with a volume of $ 5 billion, a similar analogy suggests itself if we recall the program for the creation of rocket and space technology). A competitive technological environment harmonized with world standards is being created. And since all targeted programs are deliberately focused on world-class end products, their attractiveness for Western and Russian investors and creditors will be quite high. The role of the state is to guarantee risk loans.
For Russia now, more than ever, integration into the world market of science-intensive technology is urgent. The country has almost no effective demand for a part of science-intensive products, which leads to stagnation and aging of the most advanced technological base (aviation, astronautics, electronics, computer science, communications, etc.). According to forecasts, the volume of exports for priority macrotechnologies already in the first twenty years of the 21st century will make it possible to increase the population's solvency by 2-3 times and ensure the demand for high-tech products in the domestic market. This will stimulate further economic growth.
The concept of national macro-technological priorities was met with interest not only among specialists, but also in the government. This allows us to hope that in the 21st century we are still able to make worthy choice - not in favor of the "stoker" and the "hallway".
In modern technical (and not only) literature, various variants of the concept of "technology" are widely used. It is advisable to somehow systematize these definitions.
Technology (Technology) - literally translated, the science of craftsmanship.
There are a number of domestic definitions, of which we will cite only encyclopedic ones:
1. Science or a set of information about the methods of processing raw materials, materials, semi-finished products, components, and now software into products that meet the specified requirements in terms of their technical purpose and quality.
2. The totality of means, processes, operations, methods by which elements entering into production are converted into outgoing ones; it covers machines, mechanisms, skills and knowledge.
Foreign (Western) definition: application (use) of something in industry, commerce, medicine and other fields.
Progressive technology... A technology of a higher stage of development (in comparison with the existing one), which is the result of the introduction of process innovations. This category includes technologies based on borrowed best practices when new or improved methods of manufacturing products are introduced, incl. previously implemented in industrial practice in related areas of one enterprise, other enterprises and other countries and distributed through technological exchange (non-patent licenses, know-how, engineering, etc.).
Science-intensive technology... Technology based on new or significantly improved production methods. New technology corresponds to the concept of radical product innovation, and improved - to incremental product innovation.
Science-intensive technologies are technologies focused on the production of products, performance of work and services using the latest achievements of science and technology, when the resulting product corresponds in its economic and operational properties to the best world standards and fully satisfies the new needs of society in comparison with the previously produced similar purpose. The creation of such technologies includes the provision of scientific research and development, which leads to additional costs and the need to attract scientific potential and personnel to the work. Science intensity is an indicator that reflects the proportion between scientific and technical activity and production in the form of the amount of costs for science per unit of production. It can be represented by the ratio of the number of employed scientific activities and all those employed in production (at the enterprise, in the industry, etc.).
High technology (High Technology). A technology based on the creation of new properties of products by acting on materials on the intermolecular, interatomic, intraatomic, etc. levels. Examples of such effects can be the use of nuclear radiation energy (polymerization of high molecular weight compounds), cosmic radiation (obtaining ultrapure materials), laser, plasma, ultrasonic, etc. types of processing.
Critical technology... A technology, the development of which is due to a critical situation caused by the need for urgent production of products in conditions of limited time and limited material resources. A technology that is far from optimal, when the main thing is not the cost of products, but the need to manufacture them by a certain calendar date.
The development of technological processes (TP) is the main section in the stage of the "product life cycle" associated with the technological preparation of production, and is carried out on the basis of the principles of the "Unified system of technological preparation of production" (GOST 14.001-83). TP can be developed using the existing standard or group TP. In the absence of such, the TP is developed as a single one, taking into account the previously adopted progressive solutions in the existing single TP - analogues.
The basic initial information for the design of TP are: working drawings of the product in electronic form or in hard copy, technical requirements, the volume of the annual production of products, the availability of equipment and tooling.
In mechanical engineering, a product is a product to be manufactured. A product can be a machine, device, mechanism, tool, etc. An assembly unit and a part are taken as components of the product. An assembly unit is a part of a product, the constituent elements of which are to be assembled at the enterprise separately from other elements of the product. An assembly unit, depending on the design, can either consist of individual parts, or include assembly units of higher orders and parts. There are assembly units of the first, second and higher orders. The first order assembly unit is included directly into the product. It consists of either individual parts or one or more second-order assembly units and parts. An assembly unit of the second order is dismembered into parts or assembly units of the third order and parts, etc. The assembly unit of the highest order is exploded only into parts. The considered division of the product into its component parts is made according to the technological basis.
A part is a product made of a material of the same name and brand without the use of assembly operations. Characteristic feature parts - the absence of detachable and one-piece connections in it. A part is a complex of interconnected surfaces that perform various functions during machine operation.
The production process is the totality of all actions of people and tools of labor required for this enterprise for the manufacture and repair of products. For example, the production process of making a machine includes not only the manufacture of parts and their assembly, but also the extraction of ore, its transportation, transformation into metal, and the production of blanks from metal. In mechanical engineering, the production process is part of the overall production process and consists of three stages: obtaining a blank, converting the blank into a part, and assembling the product. Depending on the specific conditions, the listed three stages can be carried out at different enterprises, in different shops of the same enterprise, and even in the same shop.
Technological process is a part of the production process that contains purposeful actions to change and (or) determine the state of the subject of labor. A change in the state of an object of labor is understood as a change in its physical, chemical, mechanical properties, geometry, and appearance. In addition, the technological process includes additional actions directly related to or accompanying a qualitative change in the production facility; these include quality control, transportation, etc. To implement a technological process, a set of production tools, called technological equipment, and a workplace are required.
Technological equipment is a means of technological equipment, in which materials or blanks, means of influencing them, as well as technological equipment are placed to perform a certain part of the technological process. These include, for example, foundry machines, presses, machine tools, test benches, etc. P.
Technological equipment is a means of technological equipment that supplements technological equipment for performing a certain part of the technological process. These include: cutting tools, fixtures, measuring instruments.
Technological equipment, together with technological equipment, and in some cases a manipulator, is usually called a technological system. This concept emphasizes that the result of the technological process depends not only on the equipment, but also, to no less extent, on the device, tool, workpiece.
A workpiece is an object of labor, from which a part is made by changing its shape, size, surface properties or material. The blank before the first technological operation is called the original blank.
The workplace is an elementary unit of the structure of the enterprise, where the performers and the serviced technological equipment, lifting and transport vehicles, technological equipment and objects of labor are located.
For organizational, technological and economic reasons, the technological process is divided into parts, which are usually called operations.
A technological operation is a part of a technological process performed at one workplace. An operation covers all the actions of equipment and workers on one or more production facilities. When processing on machines, the operation includes all the actions of the worker who controls the technological system, the installation and removal of the object of labor, as well as the movements of the working bodies of the technological system. The number of operations in the technological process can vary from one (manufacture of a part on a bar machine, manufacture of a body part on a multi-operation machine) to many tens (manufacture of turbine blades, complex body parts). The operation is formed mainly by organizational principle, since it is the main element of production planning and accounting.
In turn, the technological operation also consists of a number of elements: technological and auxiliary transitions, installation, positions, working stroke.
Technological transition is a complete part of a technological operation performed with the same means of technological equipment under constant technical conditions and installation. An auxiliary transition is a complete part of a technological operation, consisting of human actions and (or) equipment that are not accompanied by a change in the properties of the object of labor, but are necessary to perform a technological transition (for example, installing a workpiece, changing a tool, etc.). The transition can be performed in one or more work passes.
The working stroke is the finished part of the technological transition, consisting of a single movement of the tool relative to the workpiece, accompanied by a change in the shape, dimensions, surface quality and properties of the workpiece. When machining a workpiece with material removal, the term "stock" is used.
An allowance is a layer of material removed from the surface of the workpiece in order to achieve the desired properties of the surface to be produced. The layer of material removed from one surface of the finished part as a result of performing all technological transitions is called the total allowance for processing this surface.
The stage of the product life cycle (LLC), associated with the technological preparation of production, provides for:
Designing a rational workpiece;
Development of routing technology for the manufacture and assembly of products with the selection or design of initial blanks and the necessary technological equipment;
Development of operational technology for the manufacture and assembly of products with the selection or design of technological equipment (STO);
Development of technological documentation in accordance with the ESTD;
Generation of UE for equipment with CNC;
Selection or design of means of mechanization and / or automation of technological processes (TP);
Development of planning solutions for the placement of technological equipment in the envisaged area;
Keeping an archive of technological documentation;
Registration of changes in technological documentation related to design modifications or improvement of TP.
The workpiece is selected or designed based on considerations of optimizing the entire technological process (TP), including the blank stage and subsequent processing. If necessary, a feasibility study is carried out. The workpiece is designed by the technologist of the machine shop, and its manufacture is carried out according to the technology of the procurement department of the enterprise or a subcontractor.
When designing a workpiece, its dimensions are determined by the calculation results of the so-called. interoperative allowances. Allowance - a layer of material removed from the surface of the workpiece in order to achieve the specified properties of the machined surface of the part. Distinguish between the total allowance and intermediate allowances for all sequentially performed technological transitions and processing operations on a given surface of the part. The total allowance for any surface is the sum of the intermediate allowances for the same surface. Intermediate allowances are necessary to determine intermediate (for technological transitions and operations) dimensions of parts, general - to determine the dimensions of blanks. In practice, computational-analytical and experimental-statistical methods for calculating allowances are used.
Technology in any area of \u200b\u200bhuman activity is a branch of science that studies the patterns of technological processes for manufacturing products, in order to use the results of the study to ensure the required quality and quantity of products with the highest technical and economic indicators. The science of technology is not just a sum of some knowledge about technological processes, but a system of strictly formulated statements about phenomena and their deep connections, expressed through special concepts. On the other hand, the science of technology, like any branch of knowledge, is the result of human practice; it is subordinated to the goals of developing social practice and is capable of serving as a theoretical basis.
The object of the technology is the technological process, and the subject is the establishment and study of external and internal connections, the laws of the technological process. Only on the basis of their in-depth study is it possible to build progressive technological processes based on an innovative principle that ensure the manufacture of high quality products at low cost.
Modern technology is developing in the following main areas: creation of new materials; development of new technological principles, methods, processes, equipment; mechanization and automation of technological processes, eliminating the direct participation of humans in them. If the implementation of the technological process generates the need for the manufacture of tools of labor, being the reason for their appearance, then the development and improvement of tools of labor, in turn, stimulates the improvement of the process itself. The development of technology as a scientific discipline is hampered by a huge variety of production facilities (from miniature devices to nuclear power plants, from the simplest products such as a hammer to the most complex machines such as a spacecraft), countless manufacturing methods and equipment for their implementation. This is due to a large number of classifications of technologies for different signs... Here are just a few.
Technological processes on the functional composition are subdivided into blanking processes for obtaining blanks, processing blanks for obtaining parts and assembly processes.
For the high-quality functioning of procurement production, it is very important modern approach to the design of the workpiece from the point of view of optimizing the cost of its production, taking into account the volume of subsequent processing and the coefficient of material utilization. It is also necessary to take into account the volumes of production, because the approach to the construction of the technological process largely depends on this. Reducing the consumption of metals and other structural materials is achieved through their more efficient use, the use of progressive solutions in the design of new products, as well as the improvement of materials processing methods.
A significant reduction in material consumption can be achieved by switching to fundamentally new technological processes for the manufacture of blanks, the dimensions of which are as close as possible to the dimensions of finished parts. A reduction in machining allowances, in turn, is associated with an increase in the accuracy of workpieces and a decrease in the thickness of the defective surface layer. The technology of low-waste production also contributes to the intensification of machining, since in some cases roughing operations (turning, gear hobbing and others) can be excluded, which are successfully replaced by power grinding or other finishing with high cutting conditions.
As the configuration of the workpiece becomes more complex, the allowances are reduced, the accuracy of dimensions and parameters of the location of surfaces increases, the technological equipment of the blank shop becomes more complicated and more expensive, and the cost of the workpiece increases, but at the same time the labor intensity and cost of subsequent machining of the workpiece decreases, and the utilization rate of the material increases. Blanks of simple configuration are cheaper, since they do not require complex and expensive technological equipment in the manufacture, however, such blanks require subsequent laborious processing and increased material consumption.
The main thing when choosing a blank is to ensure the desired quality of the finished part at its minimum cost. The cost price of a part is determined by summing up the cost price of the workpiece according to the calculation of the procurement shop and the cost price of its subsequent processing until the specified quality requirements are achieved according to the drawing. The choice of the blank is associated with a specific technical and economic calculation of the cost of the finished part, carried out for a given volume of annual output, taking into account other production conditions.
The main technological processes of low-waste production of blanks, as is known from the course "Technology of structural materials" include: progressive methods of manufacturing cast blanks from metals and plastics; methods of obtaining blanks by hot and cold plastic deformation, including the processes of making blanks without using pressing equipment (explosion, electric pulse), cold heading and calibration to exclude subsequent machining, etc .; methods of working with any sheet materials (metals, fabrics, leather, plastics, etc.) by cutting or cutting using advanced methods (flame, plasma, laser); modern methods and equipment for cutting materials, including electrical contact, which can significantly increase productivity when working with difficult-to-cut materials. Methods and equipment of powder metallurgy have become widespread for blanks made of metal and mineral ceramics.
The basis of the technological processes for the manufacture of parts is formed by shaping methods, methods of changing the physical and mechanical properties of a material, methods of influencing the quality of the surface layer (methods of coating, finishing, painting, etc.). Shaping methods, in turn, are divided into methods with material removal and without material removal. The former are subdivided into cutting methods (turning, planing, drilling, countersinking, reaming, milling, broaching, etc.), abrasive processing methods (grinding, honing, polishing, etc.), electrophysical and electrochemical methods.
Methods without material removal include plastic deformation methods; methods of changing the physical and mechanical properties of a material include different kinds heat treatment, chemical-thermal processes.
The assembly technological process contains actions for the installation and formation of connections of parts, assembly units into a product. This takes into account the technically and economically feasible sequence of obtaining the product. The quality of an assembly unit is characterized by the accuracy of the relative movement or arrangement of parts in the assembly unit, force locking, interference in fixed joints, clearance in movable joints, quality of surface adhesion, and others.
An assembly operation is understood as the process of direct formation of an assembly unit. It usually includes orientation, connection, adjustment and fastening (fixation) of parts and assembly units. The assembly of joints can be conditionally divided into an assembly with an interference fit and without an interference fit. Interference assembly is carried out either by plastic deformation or by heat. In turn, the thermal method is implemented by heating the female part and (or) cooling the male part.
In terms of the scale of production, modern industrial production and, in particular, mechanical engineering, is conditionally divided into three types: single, serial and mass. The formation of operations for these types of industries is carried out in different ways depending on the nature, type and form of organization of the assembly process.
One-off production is characterized by a small volume of output of identical products, the re-production and repair of which, as a rule, is not provided. Products are produced in a wide range of relatively small quantities, often individually, and either do not repeat at all, or are repeated at indefinite intervals. One-off production - products that are not widely used and are manufactured according to individual orders, providing for the fulfillment of special requirements (prototypes of machines in various branches of mechanical engineering, large hydro turbines, unique metal-cutting machines, rolling mills, etc.).
In the conditions of single and small-scale production, the division into operations is carried out, as a rule, according to assembled assembly units on the basis that each machine consists of a number of assembly units: assemblies, sub-assemblies, sets and individual parts. Such a division of mechanical engineering products into assembly units is necessary to facilitate assembly and allows you to create machines according to the aggregate principle. The unification of assembly units is of great importance, since it reduces the number of special assembly units and thus helps to reduce costs. The division into separate assembly units allows their manufacture and regulation simultaneously, independently of one another, and, consequently, to reduce the time of machine production. In this case, it is desirable that each assembly unit would contain as few parts as possible.
Serial production is characterized by the manufacture or repair of products in periodic batches. Batch production is divided into small batch, medium batch and large batch. One of the indicators of belonging to a certain type of production is the so-called. the coefficient of assignment of operations to one workplace. For small-scale production, the coefficient ranges from 20 to 10, for medium-batch production, respectively, from 20 to 10, for large-batch production - from 1 to 10.
Mass production is characterized by a small nomenclature, a large volume of production, continuous production or repair of products for a long time, during which one constantly repeating operation is performed at most workplaces. In the conditions of mass and large-scale production, the formation of transitions in operations is carried out in accordance with the necessary sequence of installation and fastening of parts and other assembly units into the assembled object so that total costs the time per operation were close or multiple to the cycle of production of products. If it is possible to change the sequence of installation and fixing of assembly units, the transitions to operations are formed in such a way that one worker performs the same work and qualifications. This allows you to increase productivity, as the skills of the worker are improved, and to reduce the need for equipment and work tools.
In mass and large-scale production, special and specialized equipment is used, the reconfiguration of which to a new (not known at the time of equipment design) type of product is impossible or is associated with significant costs. In medium- and small-scale production, the main share of the equipment park is still accounted for by hand-operated machines, the reserves of increasing productivity of which are basically exhausted. Therefore, an increase in the volume of this type of production requires a proportional increase in the number of skilled workers, the shortage of which is acutely felt even with the existing production volumes. As a result, the industry has faced two counter-tasks: ensuring the flexibility of large-scale production and increasing the productivity of medium and small-scale production. Productivity (production capacity) can be defined as the number of items produced in a production system over a period of time, usually a year.
A pronounced mass production is characterized by the same constantly repeating operation over a certain period of calendar time, i.e. for such production, the coefficient of fixing operations is equal to one. Accordingly, the higher this coefficient, the lower the seriality, i.e., say, for a single production, it can reach many tens or hundreds.
If we consider a modern industrial enterprise as a whole, it can be noted that it concentrates the technologies of the main and auxiliary production and related processes. The main production is concerned with the direct change in the qualitative state of the objects of labor. As a result, changes in the properties of objects of labor can occur: physical, chemical, mechanical properties of materials and semi-finished products, the size and shape of objects of labor, the quality of the surface layer, appearance, etc. can change. For a qualitative transformation of objects of labor, energy, time and material resources are required. In this case, the technological process or its parts can be carried out with the direct participation of a person or without him.
Ancillary production is characterized by the processes that are necessary for the implementation of the main production processes. As you know, the operations of the technological process are carried out on technological equipment using technological equipment. Technological equipment must be maintained in working order and provide certain output characteristics. Therefore, most industrial enterprises the service of the chief mechanic is organized, which deals with preventive and overhaul technological equipment. Technological equipment (fixtures, processing and measuring tools) is most expedient to purchase on the side, but if special equipment is required for the main technological process, it has to be manufactured in the enterprise's tool departments. The same applies to regrinding a blunt machining tool. The service of the chief power engineer deals with the uninterrupted supply of the main production with energy. The supply service is engaged in providing the main and auxiliary production with all the necessary components and materials.
Associated Processes. During the main and auxiliary processes, as a rule, there are processes of friction, release of thermal energy and heating of the elements of the technological system, vibration, chemical reaction; all of them can both positively and negatively influence the results of the technological process. Accompanying processes are objectively operating processes regardless of our desire, so we have to take various measures to reduce their harmful effects.
The development of technical processes is carried out in the following sequence:
I. Collection of baseline data. Analysis of the service purpose of the part.
Initial data: part drawing, annual release program, release duration.
The official purpose of a part (product) is understood as a clearly formulated task for the solution of which it is used.
Service purpose analysis includes:
1. Establishment of the conditions in which the part (product) operates.
2. Determination of loads acting on the part (constant, variable, cyclic, torque, bending, etc.)
3. Classification of part surfaces.
Figure: 2.1. Part surface classification
In fig. 2.1 shows the classification of the surfaces of the stepped shaft.
Part surfaces are classified as follows:
Basic design bases (OKB) are bases that determine the position of a part in a product;
Auxiliary design bases (VKB) are bases that determine the position of parts attached to the part in question;
Executive surfaces (IP) are surfaces with the help of which the part performs its service purpose;
Free surfaces (RFs) are surfaces that define the specified contours of a part.
II. Analysis of the manufacturability of the design of the part.
This analysis is an important part in the design of the technological process and consists in the technological control of the drawing of the part.
Wherein:
1. Part drawing is analyzed:
a) the sufficiency of graphic information about the part (types, sections, sections, etc.)
b) the sufficiency and correctness of the dimensioning, roughness values, errors in the shape and location of surfaces, etc.
c) availability of information about the material of the part, coatings, its mass, heat treatment, etc.
2. The possibility of simplifying the design of the part is evaluated.
3. The possibility of using high-performance processing methods is established.
4. Compliance with the standard of structural elements of the part (chamfers, grooves, etc.) is determined.
5. In the first approximation, surfaces are outlined that will be used as initial bases.
III. The choice of the type of production and the form of its organization.
In mechanical engineering, there are three types of production: single (E), serial (C) and mass (M).
Batch production is divided into small batch (MS), medium batch (SS) and large batch (KS).
Using table 2.1, you can roughly determine the type of production, depending on the mass of the part being manufactured or the laboriousness of assembling the product and the annual production program.
Table 2.1
Selection of the type of engineering production
| Part weight, kg | Production type | ||||
| E | MC | SS | KS | M | |
| Annual production volume, pcs / year | |||||
| <1,0 | <10 | 10-1500 | 1500-100000 | 75000-200000 | >200000 |
| 1,0-2,5 | < 10 | 10-1000 | 1000-50000 | 50000-100000 | >100000 |
| 2,5 - 5,0 | < 10 | 10-500 | 500-35000 | 35000-75000 | >75000 |
| 5,0-10,0 | <10 | 10-300 | 300-25000 | 25000-50000 | >50000 |
| 10-20 | <10 | 10-200 | 200-10000 | 10000-25000 | >25000 |
| 20-300 | <10 | 10-150 | 150-1000 | 1000-5000 | >5000 |
| >300 | <5 | 5-100 | 100-300 | 300-1000 | >1000 |
For a qualitative assessment of the type of production, you can use a criterion called the rate of fixing of operations (KZO).
KZO is equal to the ratio of the number of all operations performed during the month (SO) to the number of jobs (P):
If KZO\u003e 40, then this is a one-off production; from 20 to 40 - small batch; from 10 to 20 - medium batch; more than 1 to 10 - large-scale; equal to one - mass.
There are the following forms of organization of TP: subject non-flow (E), group non-flow (MS), group variable-flow (SS) and continuous flow (KS, M).
The group form of production organization is characterized by the following features:
1. The product is put into production in batches (series) with a certain frequency.
2. The equipment is arranged according to the type of machine, creating production sites.
3. Several technological operations are assigned to each workplace.
When group form production organizations calculate the size of a batch of parts for a one-time launch into production:
where: a- launch frequency in days (take 3,6,12,24, etc.); 254 is the average number of working days per year.
The in-line form is characterized by the following features:
1. The specialization of each workplace to perform one operation (KZO \u003d 1).
2. Placement of workplaces is carried out strictly in the sequence corresponding to the TP.
The mode of operation of the production line is evaluated by the cycle of release of parts.
The release cycle (tв) is the period of time during which a unit of production should be released from the production line. It can be determined using the formula:
, min / pcs. ,
where: Fd is the actual fund of working time for the year (in hours); N - annual production program in pieces.
Table 2.2 shows the main characteristics different types production.
IV. Selection and design of the blank.
V. The choice of methods for processing individual surfaces.
Vi. Development of a technological route for manufacturing a part. Development of a processing plan and basing schemes.
Vii. Development of technological operations.
7.1. Selection of the sequence for performing technological transitions.
7.2. The final choice of machine tool, tooling, measuring and cutting tools.
7.3. Calculation of cutting conditions and time norms.
7.4. Calculation of the loading of technological equipment.
7.5. Registration of technological documentation.
VIII. Design of technological equipment.
Table 2.2
Characteristics of types of production
| Process indicator (TP) | Production type | ||
| Single | Serial | Massive | |
| 1. Form of organization of TP | subject non-flow | group | flow line |
| 2. Repeatability of products | lack of predetermined repeatability | periodic repetition of games | continuous release for a long time |
| 3. Unification of TP | use of standard TP | development of special TPs based on typical | development of special TP based on analysis |
| 4. Blank | rolling, ground casting, free forging | profile rolled products, die casting, hot stamping | specialist. rolling, die casting, cold and hot stamping |
| 5. Allowance for machining | significant | minor | minimum |
| 6. Calculation of allowances | aggregated by tables | detailed on transitions | detailed based on dimensional analysis |
| 7. Equipment | universal | universal, partly specialized | specialized and special | loading with various details without any pattern | periodic change of part on machines | continuous loading of equipment with the same parts |
| 9.KZO | over 40 | from 1 to 40 | |
| 10. Arrangement of equipment | by types and sizes | by directions of typical freight flows | along the TP |
| 11 Machine setup | lack of customization, work on measurements | on measuring instruments and devices | by standards |
| 12. Equipment | universal | universal and special | special |
| 13. Calculation of cutting conditions | according to general machine-building standards | according to industry standards and empirical formulas | analytically based on a mathematical model |
| 14. Qualification of workers | High | different | low, with highly qualified installers |
3. TECHNOLOGICAL PROCESS OF ASSEMBLING THE PRODUCT
Assembly is the final step in making machines. The scope of work during assembly in the automotive industry is up to 20% of the total labor intensity of car manufacturing.
The assembly technological process is a set of operations for joining parts in a certain sequence in order to obtain a product that meets the specified operational requirements.
The product consists of main parts, the role of which can be played by parts, assembly units, complexes, kits.
An assembly unit is a part of a product, the component parts of which are to be connected to each other at assembly operations at the manufacturing plant. Its characteristic feature is the ability to assemble separately from other elements of the product. The assembly unit of the product, depending on the design, can be assembled either from individual parts or from assembly units of higher orders and parts. There are assembly units of the first, second and higher orders. The first order assembly unit is included directly into the product. It consists of either individual parts or one or more second order assembly units and parts, etc. The assembly unit of the highest order is dismembered only into parts. Assembly units are called in practice units or groups.
An assembly operation is a technological operation of installing and forming connections of assembly units of a product. The assembly begins with the installation and fastening of the base part. Therefore, in each assembly unit, a base part must be found - this is the part from which the assembly of the product begins, attaching parts and other assembly units to it.
The sequence of execution is distinguished:
Intermediate assembly is the assembly of small elements in mechanical sections or the assembly of 2 parts before final processing;
A subassembly is an assembly of assembly units of a product;
A general assembly is the assembly of a product as a whole.
By the presence of movements of the assembled products, they are distinguished:
Stationary assembly is the assembly of a product or its main part in one workplace;
Movable assembly - the assembled product moves along the conveyor.
The organization of production distinguishes:
In-line assembly - which provides for the division of the technological process into separate technological operations, the duration of which does not exceed the cycle of product release;
Group assembly - which provides for the possibility of assembling various products of the same type at one workplace.
According to the degree of mobility, mobile and fixed connections are distinguished.
The movable joints are capable of relative movement in working condition in accordance with the kinematic diagram of the mechanism. In this case, landings with a clearance are used. No significant effort is required to assemble.
Fixed joints do not allow the connected parts to move relative to each other. Fixed joints use transitional or interference fits.
By the nature of disassembly, the joints are divided into detachable and one-piece.
Detachable connections can be completely disassembled without damaging the connected parts.
Permanent joints are assembled using press fits, welding, soldering, gluing, etc. It is impossible to disassemble them without damaging the assembled parts.
Assembly methods are determined by the product designer by setting tolerances of the mating parts.
During assembly, the dimensional chains laid down by the designer always materialize.
The method of complete interchangeability - allows you to assemble the product without any selection or additional processing of parts. The method is the least laborious, but it is necessary to increase the cost of machining.
Incomplete interchangeability method - provides that a number of connections cannot be assembled without additional refinement of parts.
Method of group interchangeability (selective assembly) - provides for preliminary sorting of parts into groups. The assembly within the group is carried out using the method of complete interchangeability. This allows you to achieve high accuracy in mates, with a slight increase in control costs (Figure 3.1).
Figure: 3.1. Selective assembly
Fitting and adjustment method - provides for the presence of a compensating link in the dimensional chain, the position of which is adjusted during assembly (clearance adjustment, spacers, etc.).
Assembly devices are classified as follows:
Clamping devices (designed for basing and securing base parts, from which the assembly of a unit or product begins);
Installation devices (designed for precise installation of the connected parts relative to each other);
Working devices (used when performing individual transitions of technological assembly operations (wrenches, presses, etc.));
Control devices.
The development of the assembly process is carried out in the following sequence:
Stage 1. Analysis of the initial data:
Study of drawings of the product and parts, technical requirements for assembly and acceptance of the product;
Choice of organizational forms of assembly;
Classification of types of connections of parts;
Choice of assembly method;
Establishing an annual release program;
Determination of the duration of the release.
Stage 2. Development of technological schemes for general and subassembly.
The study of the assembled product ends with the drawing up of technological schemes of the general (Fig. 3.2) and subassembly (Fig. 3.3). Assembly technological schemes are drawn up on the basis of assembly drawings of the product. On them, each component of the product is indicated by a rectangle divided into three parts (Fig. 3.4). Part A indicates the name of the element, part B - the numerical index according to the specification, and part C - the number of elements included in this compound. Before the numerical index of the assembly unit of the product, the letters Sb (assembly) and the order number are put: 1sb, 2sb, etc.
The element from which the assembly of the product or its assembly unit begins is called the base. By its number, they put the numerical index of the constituent part of which it belongs.
The general assembly process is shown in the diagram with a horizontal line. It is carried out in the direction from the base element of the product to the assembled object.
Above (Figure 3.2), in the order of the assembly sequence, place the symbols of all parts directly included in the product, below - assembly units. On technological schemes of subassemblies, assembly units are divided into assembly units of higher orders and parts.
Assembly technological schemes are supplied with inscriptions - footnotes explaining the nature of assembly work ("Press in", "Solder", "Rivet", "Adjust", "Check clearances", etc.) and control performed during assembly.
The diagrams reflect the possibility of simultaneous installation of several component parts of the product on its base part (Fig. 3.2, point A), which makes it possible to reduce the duration of the assembly cycle.
Figure: 3.2. Technology system general assembly
Figure: 3.3. Block assembly flow chart
Figure: 3.4. Conditional image of assembly units
Stage 3. Development of routing technology for general and subassembly.
The process of assembling a product or unit is broken down into separate operations performed in a specific sequence. One operation can include the assembly of several parts and assemblies. It is characterized by the completeness of actions.
An assembly route is a set of technological operations performed in a strictly defined sequence.
The criterion for dividing the route into operations is the release cycle t B.
It is necessary that the duration of the technological operation t pcs did not exceed the release cycle t B (t pcs< t B).
,
where: F cp - the actual annual fund of equipment operation time, in hours; N - annual program of production of products, in pieces.
Stage 4. Development of technological assembly operations.
Development is carried out in the following sequence:
Development of content and sequence of transitions;
Selection of tooling, tools, equipment;
Calculation of the norms of time for the implementation of each transition and the entire operation;
Registration of technical documentation (OK, setup drawings, assembly operational sketches).
The creation of modern efficient production facilities requires large material costs, long design and implementation times, significant efforts of specialists in various fields, the participation of many organizations and enterprises (general design organization with experienced architects, subprojects, specialists of the customer enterprise (technologists, employees department capital construction (OKS) enterprises), developers and manufacturers of equipment and technical means, installation and construction organizations). Therefore, pre-design work is of great importance for reducing design costs. They are carried out with the aim of collecting initial data, analyzing the existing level of production, development feasibility study (Feasibility study) or technical and economic calculation (Fuel and energy resources) the feasibility of creating a new, expansion, reconstruction or technical re-equipment of the existing (existing) production, the development of a technical application (technical task) for the project and the preparation of various technical materials for the design work.
Pre-designwork is most often carried out in two stages:
1) pre-design survey and development of a feasibility study or feasibility study;
2) development and approval of a technical application for the creation and implementation of a production system.
When reconstructing a production, it is necessary to have a larger amount of initial data than when designing a new production, since the project will use the buildings, structures, equipment, etc. already available at the plant. Therefore, before the start of the reconstruction, a group of designers leaves for the factory to study the production. selects and organizes the necessary information about the plant and its shops. For a comprehensive survey of the enterprise, the group includes technologists, a builder, an energy engineer, an economist and other specialists.
If the reconstruction is associated with a complete change in the production profile for the release of completely new products, not previously manufactured, the survey concerns mainly data on the site and workshops of the plant, as well as on the equipment available. The labor intensity and machine-tool intensity (the required number of machines) of the previous products are not considered in this case, since they will be different in the production of new products.
The main purpose of the survey is to study the production, material, financial and human resources of existing production. Inspection before reconstruction of production is carried out in a complex manner in several parts.
1. General and technical and economic parts contain general data on existing production, data on its composition, production volume and range of products, production cooperation, production assets; data on the composition of workers and their qualifications, the level of wages, production costs, general conclusions and basic technical and economic indicators.
2. General plan, transport and storage facilities.
3. The technological part contains information about the purpose of the workshop, manufactured products and industrial cooperation (internal and external), the location of the workshop, its mode of operation, machine-tool intensity and labor intensity of manufacturing products, organization of production, the composition of the workshop and technological processes.
4. The construction part contains data on the natural and engineering-geological conditions of the site, the characteristics of the building, the conditions of construction, access roads, areas for unloading and storage of building structures.
5. The sanitary-technical part and industrial water supply contain information about the existing sources of water supply, systems and structures of domestic and fecal, industrial sewerage, internal sanitary-technical devices.
6. The energy part contains data on the power supply and heat supply scheme, their capacity, heat and steam sources, air supply and gas supply, in-shop industrial pipelines, energy technology data from test stations, stands, data on the cooperation of energy resources.
Based on the generalized results of the survey, a feasibility study is being developed for the feasibility of creating a new production system. The feasibility study contains a brief assessment of the current state of the production system, its readiness for transformation and the expected scale of implementation, taking into account the specifics of the shop (enterprise) being surveyed and its products.
The main parameters of the production system (labor intensity, machine-tool intensity, composition and quantity of equipment, space requirement, number of employees, etc.) are determined in the feasibility study in the shortest possible time and are subject to clarification at subsequent stages of the development of technical specifications for design (preliminary design) and technological part working draft. It indicates the capital costs, technical and economic indicators that are expected to be achieved, including a decrease in machine-tool intensity and labor intensity, an increase in labor productivity, an increase in the load factor and shifts of equipment, a decrease in the number of employees, the release of production areas, a reduction in the duration of the production cycle, etc. etc.
The proposed technical solutions must correspond to the promising directions of development and implementation of new equipment and technologies, use the latest achievements in the field of resource-saving technologies, automated equipment, computer technology and its software... The created production system by the time of commissioning must correspond to the technical and economic indicators of the best domestic and foreign samples.
It is advisable to carry out automation in a comprehensive manner, that is, to automate all auxiliary processes in the shop. Complete reconstruction and technical re-equipment of the enterprise in a short time is possible only if necessary resources and appropriate planning. Otherwise, we have to confine ourselves to a partial reorganization aimed at creating separate subject-specific industries.
Survey materials also contain the reporting data of the enterprise for the year preceding the year of development of the working project, and the planned indicators of the transformed enterprise at the time of commissioning and development of the design capacity. The chief engineer of the project and the chief designer of the project check the materials of each part of the feasibility study and specify it at the inspection site.
The basis for the development technical application for the creation of a production system is a feasibility study approved by the heads of the general designer and the customer.
The basis for start of pre-design work to create a new production system is a decision of the management of the enterprise or a directive of the ministry (for an enterprise that is part of the ministry).
Development tasks the design is carried out by the customer of the project together with the design organization, taking into account the data of the feasibility study.
The basis for designingsites and workshops, their reconstruction or expansion, as well as technical re-equipment is a design assignment, which includes all the data collected during the pre-design period.
When developing technical specifications for design, it is necessary to solve the following tasks: technical, economic, organizational, social and household.
Technical tasks:
a) development of technological processes for each part (product);
b) calculation of the labor intensity of manufacturing all parts (products) per year;
c) establishing the type of equipment for each operation of all technological processes (all parts or products);
d) calculation of the required amount of all elements of production (machines, areas, workers, etc.);
e) implementation of the layout of the building, workshop and equipment layout;
f) development of labor protection issues and environment.
Economic tasks:
a) identification of the economic feasibility of the adopted technical solutions;
b) calculation of cost and profitability;
c) calculation of the size of fixed and circulating assets;
d) solving financing issues during the design, construction and development period of production, solving issues of loan repayment;
e) solving issues of supplying the enterprise with raw materials and materials, necessarily from several sources (duplication for emergency cases).
Organizational tasks:
a) development of principles for the formation of production units;
b) development of the management structure;
c) solution of issues of work organization, supply of workplaces with blanks, tools and materials;
d) organization of production services (warehouse, transport, control, etc.).
Social tasks:
a) creation of safe and comfortable working and rest conditions;
b) catering; in special cases - supply of goods and products;
c) organization of medical services.
When developing several project options (as a rule, these are 2-3 options) of mechanical assembly production or its parts, it is necessary to choose the optimal one. The optimality (efficiency) of a design solution is assessed by several indicators of various dimensions (for some indicators this is the number (pieces), for others it is the degree of convenience, for others it is the cost in rubles). In this case, a multi-criteria assessment of the quality of the solution is used. The selected indicators are assessed (weighted) according to their significance, determined based on expert judgment and statistics. Each indicator is assigned its own coefficient corresponding to the degree of importance of this indicator. Then this indicator (for example, the degree of work in progress) is multiplied by its coefficient, after which all the resulting products of indicators and the corresponding coefficients are summed up. The best option is the one with the largest (or smallest) amount.
Distinguish between two design period: pre-design and design.
Pre-design- this is the period for preparing for the design. He contains:
1. Clarification of the task. Collection of the necessary information: drawings or sketches of parts, programs for the release of each part in the near future and in the future; checking the availability of ready-made technological processes or developing absent ones (in detail for mass, large-scale and medium-batch production and enlarged for small-batch and single-batch production); calculation of the complexity of processing and assembly; calculation of the number of equipment for the main and auxiliary production; calculation of production and total area.
2. Feasibility study of the feasibility of building a new building, reconstruction, expansion or technical re-equipment of the existing production.
3. Selection of areas for construction, taking into account geological and geodetic surveys.
4. Development of technical specifications for design, taking into account all the specifications. The terms of reference is coordinated with all competent services (sanitary, fire protection, water utility, telephone, traffic police, environmental, state supervision, etc.) and then approved by the town planning council in the city hall.
5. After approval, a design permit is issued and areas are reserved for the planned construction. The permit is issued for a certain period (usually from 1 to 3 years), during which it is necessary to present the finished project.
The design specification specifies:
1. Nomenclature and volume of production (in kind and value terms).
2. Proposed layout and layout of the workshop.
3. Justification for the choice of the site, its size, relief, geo-prospecting data, conditions for the development of the site.
4. Nomenclature and volume of blanks produced and received from other enterprises.
5. Mode of operation and effective funds of equipment operating time (how many shifts and their duration, how many hours per year the equipment should work, taking into account repair and maintenance).
6. Effective fund of workers' time.
7. Requirements for environmental protection and waste disposal.
8. When and at whose expense the expansion of production is envisaged, its size.
9. The order of delivery of launch facilities.
After the approval of the terms of reference at the town planning council and obtaining a design permit begins project period (design). Design can be conducted in two stages and into one. IN one stage design is carried out in the presence of a standard project (once a project was made for someone, it was approved by all authorities and is available in the archive). This is the cheapest and fastest way to design.
IN two stages design is carried out according to unique project... In this case, first the project in accordance with the terms of reference, it is coordinated with all competent services (as well as the terms of reference), approved by the town planning council of the mayor's office and after that a building permit is issued (usually for a period of 3 years). In this case, the construction organization and the stages of construction control are usually indicated (fencing the construction site and equipping access roads, digging a foundation pit, driving piles, constructing a foundation, etc.). After approval by the town planning council of the project itself, they proceed to the second stage - preparation working documentation for the project (calculation of the required number of floor slabs, bricks, concrete, etc.).
This design sequence is used to reduce costs. So, for example, the identification of unacceptable solutions at the stage of the terms of reference will allow avoiding unnecessary costs in the design, which is estimated at about 10% of construction costs, which is several million rubles.
Design is usually carried out by a design organization that has a license for these types of work. The leading design organization may entrust some types of work to subcontractors, for example, the design of a ventilation system, power supply, etc. At the initial design stage, architects-designers are already guided by a specific construction organization, the peculiarities of the work and use of building structures, experience of cooperation, etc. With an inappropriate choice of building structures, the costs of manufacturing, transportation (sometimes even have to be brought from another region) and installation increase. It is very important to choose the right design and construction organization, because the quality of work and the absence of problems during the protection of the terms of reference and the project at the town planning council, during the construction and delivery of the object depend on this.