An integral part and basis of production is the technological process.
Technological process- is a part production process directly related to the successive transformation of an object into a product of production. During technological process there is a change in the shape and size, physical and chemical properties of objects of labor and as a result, individual parts, assemblies, assemblies and products as a whole are created. Technological, those. related to technology, to the processing of material, products according to a strictly established technology. The technological process in the production system (workshop, plant) plays a leading role because it is its improvement that determines the direction of transformation of the supporting part of the production system and, ultimately, the improvement of the production system itself. The difference in production processes is due to the variety of products of production, raw materials, starting materials, production methods, methods and methods of work, and other specific factors. It is possible to single out industries in which the technological process is based on chemical methods of processing raw materials (for example, metallurgy, chemical industries, Food Industry etc.), and industries associated with the mechanical processing of raw materials and semi-finished products (engineering, textile, woodworking, etc.). In the first of them, production is characterized by the continuity of technological processes, in the second - by their discontinuity. Accordingly, technological processes are classified into continuous and discontinuous. Increasing the degree of continuity improves production efficiency.
The technological process consists of a number of technological operations. The operation consists of a series of actions on each subject of labor. Among these actions are:
working stroke;
Auxiliary move.
working stroke- completed part technological transition, consisting of a single movement of the tool relative to the workpiece, accompanied by a change in the shape, size, surface finish or properties of the workpiece.
Auxiliary move- the completed part of the technological transition, consisting of a single movement of the tool relative to the workpiece, not accompanied by a change in the shape, dimensions, surface finish or properties of the workpiece, but necessary to complete the work stroke.
The division of the operation into working and auxiliary moves makes it possible to identify the ways of the regularities in the development of technological processes. Technological operations can be:
positional;
Checkpoints;
Positionally - through.
positional operations called those in which the workpiece is fixed in the machine, and the tool in the process of processing receives the necessary movement (grinding parts, on a grinding belt machine with a movable table).
Through operations are called those in which the workpieces in the process of processing continuously move along the machine (processing of the part on a planer). These operations are characterized by high labor productivity, i.e. workpieces pass through the machine in one direction.
Position-passing operations- operations in which the workpiece moves along the machine during processing, and then stops to perform the operation and moves again to the end of the machine (single-span press with automatic loading and unloading).
A technological operation can be divided into several operations or several operations can be replaced by one. The number of operations included in the technological process depends on the level of technology and the organization of production at a given enterprise. Enlargement or division of the operation is of great production importance. For example, dividing an operation into several operations allows the worker to better adapt to their implementation, which helps to increase labor productivity. In the structural composition technological operation includes installation, position, transition, passage.
The technological process consists of a series of operations that can be performed with one or more installations of parts.
Part of the technological process for the processing of one or more parts, performed at one workplace continuously, until moving on to the processing of the next part, is called operation .
The structure of the technological operation is best considered using the example of metalworking. The composition of the technological operation includes installation, position, transition, passage. The part of the technological operation performed with the unchanged fixing of the workpieces or assembly unit being processed is called installation. For example, drilling multiple holes in a workpiece on a multi-spindle drilling machine can be performed in one installation, i.e. with one fixing of the workpiece on the machine table. If this operation is performed on a single-spindle machine, then as many settings (fixings) of the workpiece will be required as there will be drilling holes in it.
Position - a fixed position occupied by an invariably fixed workpiece or assembly unit, together with a fixture relative to a tool or a fixed piece of equipment, to perform a specific part of an operation. For example, drilling several holes in a workpiece on a single-drilling machine using a jig can be performed in one installation (one fixing of the workpiece in the jig); the position of the workpiece relative to the tool will change as many times as it is necessary to drill holes. Thus, the same operation can be performed in one setup and one position, or in one setup and multiple positions. Labor productivity is highest with fewer installations and positions. By reducing the number of settings, a better use of the machine is achieved. A technological operation can be performed in one or more transitions.
Transition- this is a completed part of the technological operation, characterized by the processing of one surface of the workpiece, with the same tool in a given cutting mode. For example, processing a workpiece on a jointer from three sides, the operation consists of three transitions - processing the face and sequential processing of two edges. At the same time, a transition can consist of one or more passes.
passage - this is the part of the operation performed in one movement of the workpiece, when one layer of the processed material is removed. For example, to align the face of a workpiece on a jointer, depending on its curvature, not one, but several passes of the workpiece through the machine may be required.
The technological process can be divided into separate parts, stages. It depends on the complexity of the product. Knowing the structure of the technological operation, it is possible to represent the technological process in the form of a diagram (Fig. 8.21)
There are 2 components in the production system:
1. technological process of production and ensuring its functioning;
2. development of the production system as a whole.
Under production system should be understood as an organizational - integral structural unit in which a set of interrelated production processes is implemented aimed at manufacturing specific products. This is a workshop, factory, combine, etc.
For the analysis and characterization of technological processes, various parameters are used, which are selected depending on the goals set, for example, to distinguish a specific technological process from a number of similar ones, the parameters of the technological process itself are used. For example, the temperature and pressure of the working fluid, its composition, scheme technological equipment etc.
To compare processes of the same type, parameters characterizing this series of processes are used. For example, energy intensity, consumption of material resources per unit of output, etc. Such parameters are widely used, they give a fairly complete description of the technological process and allow us to trace the dynamics of its development in comparison with similar ones, but they do not reveal the deep essence of the process, which makes it possible to compare it with the whole variety of technological processes.
To identify patterns of development of technological processes in general view the parameters with the greatest accuracy, live and past labor expended within the technological process are used. The improvement of any technological process is carried out by increasing the efficiency of using past labor and reducing the cost of living labor. To show the ratio of living and past labor in a particular technological process means to give an unambiguous description of the process, and to identify the relative magnitude of the change in living and past labor means to clearly show the dynamics of the development of the process.
In order to be able to apply these indicators when studying the dynamics of the development of any technological processes, specific indicators should be used: technological equipment of labor and technological funds.
Technology funds represent the annual costs of past labor in the technological process and are defined as the sum of annual depreciation deductions from the cost of equipment and all other annual costs in the technological process, with the exception of labor costs.
Technological armament of labor represents the share of technological funds of a particular technological process per one worker in this process. The technological armament of labor shows the amount of past labor transferred to the object of labor by one worker in a given technological process.
Technological process a part of the production process is called, containing actions to change and then determine the state of the subject of production, i.e., to change the size, shape, properties of materials, control and movement of the workpiece.
A set of scientifically and practically substantiated methods and techniques used to transform materials into finished products given production is called the technology of this production.
Technological process is developed on the basis of the drawing of the product and its individual parts and determines the sequence of operations: production of workpieces of parts - casting, forging, stamping or primary processing from rolled material; processing of workpieces machine tools to obtain parts with final dimensions and shapes; assembly of components and assemblies, i.e., the connection of individual parts into assembly units and assemblies; final assembly of the entire product; product regulation and testing; product coloring and finishing.
At each stage of the production process for individual operations of the technological process, control is exercised over the manufacture of parts in accordance with the specifications.
Technological process of mechanical processing must be designed and carried out in such a way that, through the most rational and economical processing methods, the requirements for details (machining accuracy and surface roughness, relative position of axes and surfaces, correct contours, etc.) are satisfied, ensuring the correct operation of the assembled product.
According to GOST 3.1109-82, the technological process can be design, working, single, typical, standard, temporary, prospective, route, operational, route-operational.
To ensure the most rational process machining workpieces, a processing plan is drawn up indicating which surfaces need to be processed, in what order and in what ways.
In this regard, the entire process of mechanical processing is divided into separate components - technological operations.
Technological operation call the finished part of the technological process, performed at one workplace.
Depending on the size of the batch of products, their design, the level of technology and the organization of production of a given enterprise, the operation can be enlarged and dissected.
For example, in unit production, the entire assembly of parts into a product is often performed by one worker at one workplace, and it is planned as a single operation. The same work in large-scale and mass production is divided into a number of small independent operations performed by different workers at different workplaces.
Scope of operation is very important. As a general rule, the larger and more complex the operations, the lower the productivity and the more skilled the worker is required.
And, conversely, the more a large operation is divided into small ones, the higher the labor productivity and the lower the cost of processing the product. The division of a large operation allows the worker to better adapt to the performance of simple, monotonous work methods and to apply special devices.
Operation, in turn, it is divided into elements, the number of which varies depending on the volume and methods of its implementation. The main elements of the operation are the setup, technological transition, auxiliary transition, working stroke, auxiliary stroke, position.
Statutory call the part of the technological operation performed with the unchanged fixing of the workpieces being processed or the assembled assembly unit.
For example, chamfers 2X60° on the sleeve shown in fig. 3.1, but are processed in two settings, first the chamfer is removed at one end of the hole (Fig. 3.1, c), and then, rearranging the workpiece and fixing it again, the chamfer is removed at the other end (Fig. 3.1, d).
Rice. 3.1. Operation elements
Technological transition called the finished part of the technological operation, characterized by the constancy of the tool used and the surfaces formed by processing and connected during assembly.
When the cutting mode changes or cutting tool, the next transition begins.
For example, drilling a hole Ø 9 mm at the bushing (Fig. 3.1, b) is the first transition (performed by a drill), and chamfering 2X60 ° (Fig. 3.1, e) is the second transition (performed by a countersink).
Auxiliary transition- a completed part of a technological operation, consisting of human and (or) equipment actions that are not accompanied by a change in the shape, size and surface roughness, but are necessary to perform a technological transition. Examples of auxiliary transitions are workpiece setup, tool change, etc.
Changing only one of the listed elements (worked surface, tool or cutting mode) defines a new transition. The transition consists of working and auxiliary moves.
Under working stroke understand the completed part of the technological transition, consisting of a single movement of the tool relative to the workpiece, accompanied by a change in the shape, size, surface roughness or properties of the workpiece.
Auxiliary move- a completed part of the technological transition, consisting of a single movement of the tool relative to the workpiece, not accompanied by a change in the shape, size, surface roughness or properties of the workpiece, but necessary to complete the work stroke.
Position called each fixed position occupied by a permanently fixed workpiece or an assembled assembly unit together with a device relative to a tool or a fixed piece of equipment to perform a certain part of an operation.
An example of positional processing of a workpiece is the operation of drilling holes and cutting threads in them on a three-position rotary device shown in Fig. 3.2.
Rice. 3.2.
At position 1, the workpiece is fixed, when the fixture is turned to position 2, holes are drilled on the workpiece, then, at the next turn to position 3, threads are cut in the workpiece.
Operations and transitions in technological documentation, sequence numbers are given, and operations are indicated by Roman numerals, and transitions by Arabic. The sequence numbers of the transitions are given in each operation independently, starting from the first number.
Installations are designated by letters, and in each operation, the letter designation begins with the first letter of the alphabet. Moves are not indicated by signs, but their number is indicated.
Operations are called briefly by the type of processing.
For example:
- drilling,
- turning,
- milling
- etc.;
Transitions are set out in detail with the name, serial number or size of the treated surface.
For a clearer and more accurate representation of the processing method, the technological process is illustrated with sketches of processing transitions with a schematic indication of the processing surfaces, the method of mounting the part on the machine (in the fixture), the position of the part, fixture and tools. Thus, these sketches depict technological setups for surface treatment of a part. The sketch is given for each transition separately. Examples of hole machining sequences are shown in fig. 3.3.
Rice. 3.3. Examples of processing transitions:
a - drill a hole Ø D,
b - countersink hole Ø D,
c - expand the hole Ø D rough (clean),
g - countersink chamfer h X a when machining a hole
ESSENCE OF THE TECHNOLOGICAL PROCESS
Distinguish between manufacturing process and technological process. The production process includes all, without exception, the work associated with the manufacture of products in the enterprise. The production process includes the processing of material (raw materials) in order to turn it into products (products) manufactured by the plant; work on the delivery, storage and distribution of raw materials; production and repair of tools: repair of equipment; supply of electricity, light, heat, steam, etc. The technological process covers work directly related to the transformation of raw materials into finished products. Technological process - the main part of production (production process). The technological process consists of a number of production operations that are performed in a strictly defined sequence. A production operation is a part of the technological process performed at a specific workplace with a specific tool or on specific equipment. Operations follow in the technological process in a strictly established order. The degree of operational dissection of the technological process depends on the amount of work for the manufacture of this product, on the number of workers involved in the manufacture of the product, on the size of the production facility (working area), on the nature of the workplace equipment and other production conditions. The deepest division of the technological process into operations should be considered when each operation is performed in one step without changing the tool. The smaller the operation, the easier and more accessible it is to perform. Therefore, the deeper the operational breakdown of the technological process, the higher labor productivity and the less need for highly skilled workers. The technological process can be general for the manufacture of the entire product or cover, for example, only the processing of parts, only the assembly operations or the operations of finishing products. The technological process should not be confused with the production technology. Under the production technology, one must understand not only the sequence of operations performed, but also the methods and techniques for performing these operations. Production technology should be based on the latest achievements of science and technology, taking into account the experience of innovators and innovators. The place in production where any production operation is performed is called a workplace. Machines, mechanisms, stationary devices installed at the workplace, etc. e. permanent fixtures, fixed motionless, constitute the equipment of the workplace. From how organized workplace, on the provision of its tools and fixtures, on the location of materials, tools and fixtures relative to the permanent equipment of the workplace and relative to the worker himself, on the preparedness of equipment, tools and materials for work, on the quality of care for the workplace and equipment - labor productivity depends on all this and product quality.
The division of the technological process according to the workshops allows:
1) it is most rational to equip each workshop with machines, mechanisms, devices, according to the nature of the work performed in it;
2) create in the workshop best conditions labor, taking into account the peculiarities of work in it;
3) adapt the premises and equipment of the workshop to perform work in accordance with the requirements of safety, labor protection and fire protection for these types of work;
4) to manage the work of the shop most efficiently and skillfully, to exercise fuller quality control over the work;
5) rationally organize jobs.
The division of the technological process into processing stages allows:
1) place machines, mechanisms and other equipment in the best production sequence, ensure mechanized supply of materials to them;
2) organize work in teams and units.
A technological operation is a part of a technological process that is performed continuously at one workplace, on one or more simultaneously processed or assembled products, on one or more workers. The condition of the continuity of the operation means the performance of the work provided for by it without switching to the processing of another product. The technological operation is the basic unit production planning and accounting. On the basis of operations, the labor intensity of manufacturing products is determined and time standards and prices are set, the required number of workers, equipment, fixtures and tools is set, the cost of processing is determined, scheduling production and quality control and deadlines for the execution of work. In conditions automated production an operation is understood as a complete part of the technological process, performed continuously on an automatic line, which consists of several machines connected by automatically operating transport and loading devices. In the conditions of FAP (flexible automatic production), the continuity of operations can be disrupted by sending workpieces to an intermediate warehouse in the periods between individual positions performed on different technological modules. In addition to technological operations, TP includes auxiliary operations. To support operations include - transport, control and measuring, etc., i.e. operations that do not change the size, shape, appearance or properties of the product, but necessary for the implementation of technological operations.
The strength at a certain time during hardening under normal conditions depends mainly on the activity of the cement and the water-cement ratio. Rb = A, the dependence follows from the physical essence of the formation of the concrete structure and is graphically depicted in the form of hyperbolic curves.
graph of dependence on concrete strength and W / C. 1:n - the ratio of the mass of cement to aggregate. 1. Concrete on crushed stone, 2. Concrete on gravel. Hardening cement, depending on its quality and hardening time, adds only 15-20% of water. At the same time, to make the concrete mixture plastic, water is added to the concrete, i.e. 40-70% by weight of cement. With W / C = 0.2-0.25, the mixture turns out to be dry and we cannot mix and lay it with high quality. When we add more water, the excess water either remains or the concrete capillaries or evaporates. Thus, the W / C law expresses the dependence of concrete strength on density and porosity. The W / C law is fulfilled within certain limits at very low W / C, even with an increased consumption of C and W, it is not possible to obtain the workability of the mixture and the required concrete density. The strength of concrete may decrease. For cement hydration, a certain excess of water is always required, approximately 2-3 times, compared to the amount that directly enters with the cement.
The dependence of strength on W / C is observed only in those cases when concrete is tested on the same materials and similar workability of the concrete mixture and when using the same methods of formation and compaction.
The strength of concrete is significantly affected by the type and quality of aggregates, methods of preparation and other factors. In fact, there is one strict curve expressing the dependence of strength on W / C, and some band, the area in which most of the tests fit. The formula for determining the strength of concrete, depending on the quality of cement, aggregates and other factors, is taken into account by applying empirical coefficients. In practice, the actual strength of concrete may differ from the calculated one by 1.3 - 1.5 times; therefore, the concrete compositions obtained in the calculations are always checked on control samples. In practice, the formulas use independent strengths from W / C, and the inverse dependence of the strength of concrete on C / W. When the C/V ratio changes within 1.2-2.5, the dependence is straightforward and is determined by the formula Rb=ARc(C/V-s), A,s are empirical coefficients that take into account the influence of fillers, in the general case, A=0 ,3; c=0.5 This dependence is valid for densely laid concrete. In rigid concrete mixes that require careful compaction, entrained air may remain, in which case the amount of entrained air adds to the pore volume of the remaining mixing water.
The technological process is usually divided into parts called operations.
Technological operation call the finished part of the technological process, performed at one workplace. An operation encompasses all the activities of equipment and workers on one or more jointly processed or assembled objects of production. So, when processing on machine tools, the operation includes all the actions of the worker to control the machine, as well as automatic movements of the machine associated with the process of processing the workpiece until the moment it is removed from the machine and the transition to the processing of another workpiece.
The operation is characterized by the invariability of the workplace, technological equipment, the object of labor and the performer. When one of these conditions changes, a new operation takes place.
The content of the operation is determined by many factors and, above all, organizational and economic factors. The scope of work included in the operation can be quite wide. The operation can be the processing of only one surface on a separate machine. For example, milling a keyway on a vertical milling machine. The manufacture of a complex body part on an automatic line, consisting of several dozen machines and having a single control system, will also be an operation.
The technological operation is the main element of production planning and accounting. Operations determine the complexity of the process, necessary equipment, tools, fixtures, qualifications of workers. All planning, accounting and technological documentation is compiled for each operation.
The operations that are part of the technological process are performed in a certain sequence. The content, composition and sequence of operations are determined process structure .
The sequence of passage of the workpiece of a part or assembly unit through the shops and production sites of the enterprise when performing the technological process of manufacturing or repair is called technological route .
Distinguish intershop and intrashop technological routes.
The structure of the operation involves dividing it into constituent elements– setups, positions and transitions.
To process a workpiece, it must be installed and fixed in a fixture, on a machine table or other type of equipment. When assembling, the same should be done with the part to which other parts are to be attached.
setup- part of the technological operation, performed with the unchanged fixing of the workpieces being processed or the assembled assembly unit.
Each time the workpiece is removed again and then fixed on the machine, or when the workpiece is rotated through any angle to machine a new surface, a new setting takes place.
Depending on the design features product and the content of the operation, it can be performed either from one or from several installations. In the technological documentation, the installations are indicated by the letters BUT, B, AT etc. For example, when processing a shaft on a milling and centering machine, the milling of the ends of the shaft on both sides and their centering are performed sequentially in one setting of the workpiece. Complete processing of the shaft workpiece on a screw-cutting lathe can be carried out only with two workpiece settings in the centers of the machine, since after processing the workpiece on one side (setting BUT) it must be unfastened, turned over and installed in a new position (installing B) for processing on the other side. In the case of turning the workpiece without removing it from the machine, it is necessary to indicate the angle of rotation: 45 o, 60 o, etc.
The installed and fixed workpiece, if necessary, can change its position on the machine relative to the tool or working bodies of the machine under the influence of linear movement devices or rotary devices, taking a new position.
Position called each individual fixed position occupied by an invariably fixed workpiece or an assembled assembly unit together with a fixture relative to a tool or a fixed part of the equipment when performing a certain part of the operation. When machining a workpiece, for example, on a turret lathe, the position will be each new position of the turret. When processing on multi-spindle automatic machines and semi-automatic machines, the invariably fixed workpiece occupies different positions relative to the machine by rotating the table, which sequentially brings the workpiece to different tools.
Technological transition- a completed part of the technological operation, performed by the same means of technological equipment under constant technological conditions and installation. Technological transition, therefore, characterizes the constancy of the tool used, the surfaces formed by processing or connected during assembly, as well as the invariance of the technological regime.
For example, technological transitions will be making a hole in the workpiece when processing with a twist drill, getting a flat surface of a part by milling, etc. Sequential processing of the same hole in the gearbox housing with a boring cutter, countersink and reamer will consist of three technological transitions, respectively, since a new surface is formed during processing with each tool.
In the turning operation, the scheme of which is shown in Fig. 11a, two technological transitions are performed. Such transitions are called simple or elementary. The set of transitions, when several tools are involved in the work at the same time, is called combined transition(Fig. 11b). In this case, all tools work with the same feed and speed. In the case when there is a change in sequentially machined surfaces with one tool with a change in cutting conditions (speed when processing on hydrocopy machines or speed and feed on CNC machines), with one tool stroke, there is difficult transition.
Technological transitions in this case can be performed sequentially (Fig. 11, a) or in parallel-series (Fig. 11, b).
When processing workpieces on CNC machines, several surfaces can be sequentially processed by one tool (for example, a cutter) when it moves along a path specified by the control program. In this case, we say that the specified set of surfaces is processed as a result of executing instrumental transition.
Examples of technological transitions in assembly processes can be works associated with the connection of individual parts of the machine: giving them the required relative position, checking the achieved position and fixing it with fasteners. In this case, the installation of each fastener (for example, a screw, bolt or nut) should be considered as a separate technological transition, and the simultaneous tightening of several nuts using a multi-spindle wrench should be considered as a combination of technological transitions.
A technological operation, depending on the organization of the technological process, can be carried out on the basis of concentration or differentiation of technological transitions. With the concentration of transitions, the structure of the operation includes the maximum possible number of technological transitions under given conditions. This organization of the operation reduces the number of operations in the process. In the limiting case, the technological process may consist of only one technological operation, including all the transitions necessary for the manufacture of the part. When differentiating transitions, they tend to reduce the number of transitions included in the technological operation. The limit of differentiation is such a construction of the technological process, when each operation includes only one technological transition.
A characteristic feature of the technological transition in any processes (except hardware ones) is the possibility of its isolation at a separate workplace, i.e. isolating it as a stand-alone operation. In the case of a single-transition operation, the concept of an operation may coincide with the concept of a transition.
When organizing the processing process according to the principle of differentiating the construction of an operation (rather than a transition), the technological process is divided into one-, two-transitional operations, subject to the duration of the release cycle. If operations (for example, gear hobbing, spline milling) go beyond the limits of the release cycle in duration, then backup machines are installed. Therefore, the limit of differentiation is the release cycle.
The principle of concentration of operations is divided into the principle of parallel concentration and sequential. In both cases, one operation concentrates a large number of technological transitions, but they are distributed among positions in such a way that the processing time for each operation is approximately equal to or less than the release cycle. The time limit for the operation will be determined by the longest time by position. According to the principle of sequential concentration, all transitions are performed sequentially, and the processing time is determined by the total time for all transitions.
Technological transition during cutting may consist of several working moves.
Under working stroke understand the completed 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 or properties of the workpiece. The number of working moves performed in one technological transition is chosen based on the provision of optimal processing conditions, for example, reducing the depth of cut when removing significant layers of material.
An example of a working stroke on a lathe is the removal of one layer of chips with a cutter continuously, on a planer - the removal of one layer of metal over the entire surface, on a drilling - drilling a hole to a given depth.
Working strokes take place in those cases when the allowance exceeds the possible depth of cut and it has to be removed in several working strokes.
When repeating the same work, for example, drilling four identical holes in series, there is one technological transition performed in 4 working steps; if these holes are made simultaneously, then there are 4 combined working strokes and one technological transition.
The operation also includes elements associated with the implementation of auxiliary movements and necessary for the implementation of the technological process. These include auxiliary transitions and tricks.
Auxiliary transition- a completed part of a technological operation, consisting of human and (or) equipment actions that are not accompanied by a change in the shape, size or properties of the surface, but are necessary to complete the technological transition.
Auxiliary transitions include, for example, fixing a workpiece on a machine or in a fixture, changing a tool, moving a tool between positions, etc. For assembly processes, transitions can be considered auxiliary when installing a base part on an assembly stand or in a fixture on a conveyor, moving attached parts to it and etc.
Auxiliary moves and techniques are also necessary to perform a technological operation.
Auxiliary move- the completed part of the technological transition, consisting of a single movement of the tool relative to the workpiece, necessary for the preparation of the working stroke.
Under reception understand the complete set of actions of the worker used in the performance of the transition or part of it and united by one designated purpose. For example, the auxiliary transition "set the workpiece in the fixture" consists of the following steps: take the workpiece from the container, install it in the fixture, fix it.
Auxiliary moves and techniques are taken into account when studying the costs of auxiliary time for performing an operation.
Any technological process takes place in time. The interval of calendar time from the beginning to the end of any periodically repeating technological operation, regardless of the number of simultaneously manufactured or repaired products, is called technological operation cycle .
The preparation of technological equipment and technological equipment for the performance of a technological operation is called adjustment . Setup includes setting up a fixture, switching speed or feed, setting a set temperature, etc. Additional adjustment of technological equipment and (or) equipment in the process of work to restore the values of parameters achieved during adjustment is called adjustment .
3.2 Technology transition
Technological transition is called the completed part of the technological operation, performed by the same means of technological equipment with constant technological modes and installation. If the tool was changed during the turning of the roller, then the processing of the same surface of the workpiece with this tool will be a new technological transition (Figure 3.3). But the tool change itself is an auxiliary transition.
Figure 3.3 - Scheme of technological transition
An auxiliary transition is a completed part of a technological operation, consisting of human and (or) equipment actions that are not accompanied by a change in the properties of the object of labor, but are necessary to complete the technological transition. Transitions can be combined in time due to the simultaneous processing of several surfaces, i.e., they can be carried out sequentially (rough, semi-finishing, finishing turning of a stepped shaft or drilling four holes with one drill), parallel (turning a stepped shaft with several cutters or drilling four holes, at once four drills) or parallel-sequential (after turning the stepped shaft simultaneously with several cutters, simultaneous chamfering with several chamfering cutters or drilling four holes in series with two drills).
Installation - a part of the technological operation, performed with unchanged fixing of the workpieces being processed or the assembled assembly unit. Turning parts to any angle is a new setting. If the roller is first turned in a three-jaw chuck with one setting, and then it is turned over and turned, then this will require two settings in one operation (figure 3.4).
Figure 3.4 - Scheme of the first (a) and second (b) installation
3.3 Position
The workpiece installed and fixed on the rotary table, subjected to drilling, reaming and countersinking, has one setup, but with the rotation of the table it will take a new position.
A position is a fixed position occupied by a rigidly fixed workpiece or an assembled assembly unit together with a fixture relative to a tool or a fixed part of the equipment when performing a certain part of the operation. On multi-spindle machines and semi-automatic machines, the workpiece, with one of its fixings, occupies different positions relative to the machine. The workpiece is moved to a new position along with the clamping device (figure 3.5).
When developing a technological process for processing workpieces, it is preferable to replace setups with positions, since each additional setup introduces its own processing errors.
Figure 3.5 - Scheme of changing workpiece positions on a multi-spindle machine
3.4 Working and auxiliary stroke
The working stroke is the completed 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. The working stroke usually accompanies the continuous processing of one layer of the workpiece, for example, on a lathe - processing a shaft per pass, on a planer - one movement of the cutter during cutting.
Auxiliary stroke is the completed part of the technological transition, consisting of a single movement of the tool relative to the workpiece, necessary to prepare the working stroke. For example, when rough turning a shaft, the cutter returns to its original position, making an auxiliary stroke.
3.5 Reception
A technique is a complete set of human actions used in the performance of a technological transition or part of it and united by one purpose. Usually, the reception is an auxiliary action of the operator when controlling the machine (manually), measuring the workpiece. Receive element - pressing a button, moving a handle, etc.
Important characteristics of the technological process and operation are the cycle, technological operation, tact and rhythm of release.
3.6 Cycle, beat and rhythm release
The cycle of a technological operation is the interval of calendar time from the beginning to the end of a periodically repeating technological operation, regardless of the number of simultaneously manufactured products.
Tact is the time interval through which the release of products or blanks of certain names, sizes and designs is periodically performed.
The release rhythm is the number of products or blanks of certain names, sizes and designs produced per unit of time.
It is desirable that the time spent on the execution of one operation be equal to the release cycle time or a multiple of it. Such a correction of the time spent on the operation is achieved by one or another degree of concentration of operations, the use of optimal processing modes, the reduction of auxiliary time due to multiple devices, automation of loading, transportation, the use of more high-performance equipment, parallel operation on the same type of backup machines, etc.
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