What is the workflow. Technological operation and its elements. Algorithm for designing TP for the manufacture of machine parts
Technological operation- this is a complete part of the technological process, performed at one workplace.
A technological operation is the basic unit of production planning and accounting. On the basis of operations, the complexity of manufacturing products is determined and norms of time and prices are established, the required number of workers, technological equipment is determined.
setup- part of the technological operation, performed with the unchanged fixing of blanks or assembled assembly units. Designation of the installation A, B, C, D, etc.
Position- a fixed position of the device with the workpiece permanently fixed in it relative to the working bodies of the equipment for performing part of the technological operation.
Technological transition- the finished part of the technological operation, characterized by the constancy of the tool used and the surfaces formed during processing or connected during assembly. Accompanied by a change in the state of the production object.
working stroke- the completed part of the technological transition, consisting of a single movement of the tool relative to the production object, accompanied by a change in the state of the object.
Auxiliary transition- a completed part of a technological operation, consisting of the actions of a worker and equipment. It is not accompanied by a change in the state of the production object, but is necessary to perform a technological transition.
Auxiliary move- the completed part of the technological transition, consisting of a single movement of the tool relative to the production object, and not accompanied by a change in its state.
Algorithm for designing TP for the manufacture of machine parts
1) analysis of initial data; 2) search for analogues of the technical process; 3) selection of the initial workpiece; 4) selection of technological bases; 5) drawing up a technological processing route; 6) development of technological operations; 7) regulation of the technological process; 8) determination of safety requirements; 9) choice the best option; 10) design of the technical process.
Determination of cutting conditions during machining (single and multi-tool)
Single tool processing .
1 ) Determine cutting depth t according to the results of the calculation of operating allowances. In single-pass machining, we take the average value of the allowance. If there are two passes, then 70% of the allowance is removed for the first pass, and 30% for the second.
2 ) Assign filing s. For turning, drilling, grinding, the feed per revolution of the workpiece is determined. S o or tool, for milling - feed per tool tooth S z .S z =S o /z, where z is the number of cutter teeth. When roughing, the maximum allowable feed is selected; when finishing - depending on the required accuracy and roughness of processing, taking into account the geometric parameters of the cutting part of the tool. The amount of feed determined according to the standards or using other methods (linear programming, simplex method, etc.) must be coordinated with the passport data of the machine.
3 ) Determine cutting speed value v:
where the values of the coefficients are determined from reference books.
4 ) We expect frequencyn workpiece or tool rotation:
where v - cutting speed, m/min; D is the diameter of the workpiece (tool) in mm.
5 ) We calculate the coordinate components of the cutting force using formulas of the form:
values other than t and S are selected from reference tables.
6) We check the cutting mode according to the power and power characteristics of the machine. To do this, we compare the obtained value of the coordinate component P x of the cutting force acting in the feed direction with the allowable force of influence on the feed mechanism R x add.
Cutting power:
N e \u003d, kW or other dependencies with verification
N e ? N dvz,
where N dv is the power of the drive motor of the main movement of the machine, s is the efficiency of the drive.
If the given ratios are not maintained, it is necessary to correct the selected values of feed and cutting speed or replace the process equipment.
Multi-tool processing.
In the case of parallel processing, the depth of cut and feed for each of the tools are selected from the condition of their independent operation, i.e. according to the method of single-tool processing. Then the feed of the tool block is determined - the smallest technologically admissible feed from the selected values. The cutting speed is determined by the presumably limiting tool. They can be tools that process areas of the largest diameter and greatest length. For several supposedly limiting tools, the cutting time coefficients are found:
where Lp is the cutting length of an individual tool, Lpx is the length of the working stroke of the entire tool block.
where Tm is the normalized tool life.
Based on the found values of resistance T, cutting speeds are found for each of the supposedly limiting tools. In fact, the limiting tool will be the one with the lowest defined cutting speed. This value is adopted for the operation of the entire tool block. Next, the rotational speed is determined n and its adjustment is carried out according to the passport of the machine. Next, we calculate total cutting force and power.
Technological transition is a completed part of the technological operation performed on one or more surfaces of the workpiece, one or more simultaneously working tools without changing or with automatic change in the operating modes of the machine.
Elementary transition- part of the technological transition, performed by one tool over one area of the surface of the workpiece being machined in one working stroke without changing the operating mode of the machine.
Auxiliary transition- a completed part of the technological operation, consisting of human and equipment actions that are not accompanied by a change in the shape, size and surface roughness of the objects of labor, but are necessary to complete the technological transition (installation of the workpiece, tool change, etc.).
working stroke
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, surface quality or properties of the workpiece, but necessary for the preparation of the working stroke.
Operation- it technological process system, aimed at achieving the goal, through a controlled transformation of the products of the operation. Depending on the level of a particular system, an operation is performed, it can be attributed to one of the following types:
7. The concept of working and idling, setting and position
working stroke- this 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.
Idling- the mode of operation of a device, usually a source of mechanical or electrical energy, when the load is disconnected.
Statutory call the part of the technological operation performed with the unchanged fixing of the workpieces being processed or the assembled assembly unit.
Position called each fixed position occupied by a permanently fixed workpiece or assembled assembly unit together with a fixture relative to a tool or a fixed piece of equipment to perform a certain part of an operation
8. Technology as a science and as a process
Technology is understood as a set of techniques and methods for obtaining, processing or processing raw materials, materials, semi-finished products or products carried out in the production process. technology (or technological processes ) also call a certain sequence of production operations, actions that ensure the manufacture of any product of a given quality. Accurate execution of all operations and compliance with their sequence is a guarantee of the release of products of a given quality and in the right quantity.
Technology as a science deals with the identification of physical, chemical, biological patterns in order to develop and use the most efficient and economical production processes.
There are many technologies. Each sphere of human activity has its own specific technologies. But there are technologies that every person should own. This is primarily the technology of communication, the technology of housing care, etc. There are also a number of very common technologies that are included in the content of the work of people working in the most popular professions. These are technologies for processing wood and metal, technologies for repair and construction work in the house, etc. In the classroom for academic discipline- technology - you will get acquainted with the technology of processing the most common materials - wood and metal, the technology of repair and construction work, elements of the culture of the house.
9. Technological documentation. types and content of documents.
Technological documentation is called documents that regulate the implementation of the technological process of manufacturing parts. The technological documentation thus serves as the basis for guiding the production process.
In order for the technical process to be carried out at each workplace without delays and violations, it is necessary to carry out special preparatory work. Therefore, technological documentation must contain comprehensive information not only for the implementation of the technological process itself, but also for the preparation of production.
Types of technological documents are established by GOST 3.1102-70, and the rules for drawing up general-purpose documentation - GOST 3.1105-71.
As part of technological documentation for processes machining includes: route map, operational map, map of sketches and diagrams, specification of technological documents, technological instruction, material sheet, equipment sheet and other documents. Technological documents are divided into text and graphic.
Text includes instructions, descriptions and other documents containing solid text, as well as process maps, statements and other documents where the text is divided into columns. A route map (MC) is a document containing a description of the technological process of manufacturing a product for all operations in a technological sequence, indicating the relevant data on equipment, tooling, material, labor and other standards. Operating card (OK) - a document containing a description of the operations of the technological process of manufacturing a product with a breakdown of operations by transitions and indicating operating modes, design standards and labor standards.
A map of sketches and diagrams (CE) is a document that contains a graphic illustration of the technological process of manufacturing a product and its individual elements, supplementing or explaining the content of operations.
A process instruction (TI) is a document containing a description of specific work methods, process control methods, rules for using equipment and instruments, safety measures, as well as a description of the physical and chemical phenomena that occur during the performance of individual operations of the process.
The material sheet (BM) is a document containing preliminary data for the preparation of production. It is compiled on the materials used in the performance of the technological process of manufacturing the product. VM is a detailed and summary sheet of material consumption rates. Equipment list (VT) - a document containing a list of special and standard fixtures and tools necessary to equip the technological process of manufacturing a product. This statement is compiled on the basis of process maps.
10. General classification of engineering materials
1. Structural steels and alloys.
1.1. Carbon structural steels.
1.2. Alloyed structural steels.
1.3. Construction low-carbon steels.
1.4. Reinforcing steels.
1.5. Steels for cold forming.
1.6. Structural (machine-building) cemented (nitrocarburized) alloy steels.
1.7. Structural (machine-building) improved alloy steels.
1.8. Steels with high machinability.
1.10. High-strength steels with high ductility (TRIP or PNP steels)
1.11. Spring-spring steels of general purpose.
1.12. Ball bearing steels.
1.13. Wear resistant steels.
1.14. Corrosion-resistant and heat-resistant steels and alloys.
1.15. cryogenic steels. 1.16. Heat-resistant steels and alloys.
2. Tool steels and hard alloys.
2.1. Steel for cutting tools.
2.2. Steel for measuring tool.
2.3. Steels for cold forming dies.
2.4. Steels for hot forming dies.
2.5. hard alloys.
3. Steels and alloys with special physical properties.
3.1. Magnetic steels and alloys.
3.2. Metal glasses (amphora alloys).
3.3. Steels and alloys with high electrical resistance for heating elements.
3.4. Alloys with a given temperature coefficient of linear expansion.
3.5. Alloys with "shape memory" effect.
4. Refractory metals and their alloys.
11. Physico-mechanical and technological properties materials
Technological operation- completed part of the technological
process performed at one workplace. For surgery
the norm of time is determined and the operation is thus
unit for planning the scope of work and jobs in the shop
Technological operation is the main structural unit of TP. This part of the process associated with the processing of one or more simultaneously processed workpieces, one or more simultaneously working workers, at one workplace and continuously.
Continuity condition operations means the performance of the work envisaged by it without switching to the processing of another product or the same product, but at a different workplace. For example, processing a stepped roller in centers on lathe represents one technological operation, if it is performed in the following sequence: the workpiece is installed in the centers, the roller is turned from one end, the workpiece is removed, the clamp is reinstalled and the workpiece is reinstalled in the centers, the roller is turned from the other end.
Work similar in content to the roller can be performed in two operations:
Fasten the clamp, set the workpiece in the center, grind from one end and remove the clamp
Fasten the clamp on the other end of the workpiece, install it in the centers and grind from the other end.
However, these actions will be included in different operations if the secondary installation and processing of the second end of the roller does not follow immediately after processing the first end, but with a break to process other workpieces of the batch (i.e., first all workpieces are processed from one end, and then everything - from the other). The above example shows that the composition of the operation is established not only on the basis of purely technological considerations, but also taking into account organizational expediency.
The technological operation is the main unit of production planning and accounting. On the basis of operations, the complexity of manufacturing products is determined and time standards and prices are established.
Technological transition
operations performed by the same means
technological equipment at constant technological
modes and settings.
Auxiliary transition - completed part of the technological
operation, consisting of the actions of a person and / or / equipment,
which are not accompanied by a change in the properties of the objects of labor, but
necessary to perform a technological transition /example -
workpiece setting, tool change, etc./. Auxiliary
transitions are not recorded in the workflow. At
simultaneous processing by several tools of several
transition surfaces is called combined. Often found
operations consisting of only one technological transition.
working stroke - the completed part of the technological transition,
consisting of a single movement of the tool relative to
workpiece and is accompanied by a change in shape, size, quality
surface and workpiece properties.
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 it is removed from the machine and the transition to processing 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. Manufacture of a complex body part on an automatic line, consisting of several dozen machines and having single system control 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 A, B, V 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 A) 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 is called each separate 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 working stroke of the tool, 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 setting 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.
characteristic feature technological transition in any processes (except for 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, a large number of technological transitions are concentrated in one operation, 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 selected based on the provision optimal conditions processing, such as 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 by 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 purpose. For example, the auxiliary transition "install the workpiece in the fixture" consists of the following steps: take the workpiece from the container, install it in the fixture, and 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 .
The internal combustion engine is still the most popular invention to this day. It is designed to actuate a variety of mechanisms. A rather serious terminology revolves around this invention, which is not clear to all drivers. Today you will learn what the engine stroke (piston stroke) and.
ICE piston working stroke
To know what it is, you need to understand. The working stroke is such a movement of the piston, in which the motor performs useful, namely, it converts thermal energy at torque.
To begin with, we will analyze all the cycles of the engine and will reach the moment when the piston will perform this very useful work. The first step is the intake stroke. At this time, the piston moves down, and the valve that allows the air-fuel mixture to enter opens. It is supplied in a certain ratio and completely fills the combustion chamber. This continues until the piston reaches bottom dead center.
As soon as the piston goes up, the valves will be closed, at this moment the mixture is compressed and the pressure inside the chamber increases. As soon as the piston reaches top dead center, the moment of the piston stroke comes. A spark will appear on the spark plug electrodes, which will ignite the mixture and cause a small explosion, which will cause the piston to go down. As long as the piston goes to the lowest point of the cylinder, this segment will be considered its working stroke. Then the whole cycle is repeated due to the inertia of the crankshaft.
It is worth noting that it is the working stroke that is the main indicator of the efficiency of the engine, which means that we fully determine its efficiency.
At this time, all the rest of the work spent on inertia: compression of the mixture and its supply - all this creates an extra load on the crankshaft, however, without this, the engine cannot work. Many automakers increase the stroke and increase the volume of the cylinder in order to achieve the greatest efficiency by increasing the stroke and the volume of the mixture to be burned.
Video - Idling and other engine modes
What is engine idling
The idling of any internal combustion engine is called such a mode of operation in which there is no required mechanism. This mode is typical not only for internal combustion engines, it is also actively used for many other types. power plants, however, it has become more widespread precisely in such types of engines.
This mode is provided due to the clutch, which can "break" the transmission of torque from the flywheel to the input shaft, as well as the neutral position of the gearbox handle, in which there is no transmission of torque to the drive or cardan shaft.
The operation of the engine at idle allows you to maintain its speed at the required level without stopping. The fact is that in the presence of a load on the crankshaft, the internal combustion engine always tends to stop, so oxygen in this case is consumed in small quantities. This mode also allows you to warm up the engine, and on injection engines it creates work in which the content of harmful substances in the exhaust smoke is minimized.
A large number of "legends" go around idle mode. For example, many drivers find idling to be the most economical mode. However, this is not so, rather, on the contrary, idling becomes the cause of the maximum fuel consumption. The fact is that when completely, so that the engine does not stop, the fuel supply system provides an increase in the content of gasoline in the combustion chamber, and when the throttle is opened, the level of gasoline in the mixture decreases, as oxygen consumption increases. In this mode, the engine rather works due to the resulting inertia after the useful stroke of the piston. It is generally accepted that the most economical mode of operation of the internal combustion engine is the moment when the revolutions are at around 3000 rpm. At this point, the throttle valve opens fully, and the fuel level in the combustion chamber is at a minimum.
The stability of the idle speed is supported by the fuel supply system. It depends on her how the motor will work itself when there is no load on the shaft, and the throttle valve, at the same time, is closed.
That's all there is to know about the most confusing terms in internal combustion engine theory. All this applies not only to car engines, because such a motor is also installed on motorcycles, chainsaws, boats and even airplanes.
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