In mechanical engineering, there are three types of industries: mass, serial and single and two working methods: flow and non-flow.

Mass production characterized by a narrow range and a large volume of products produced continuously for a long time. main feature mass production is not only the number of manufactured products, but also the performance at most workplaces of one constantly recurring operation assigned to them.

The release program in mass production makes it possible to narrowly specialize workplaces and locate equipment along the technological process in the form of production lines. The duration of operations at all workplaces is the same or a multiple of time and corresponds to the specified performance.

The release cycle is the time interval through which the release of products is periodically produced. It significantly affects the construction of the technological process, since it is necessary to bring the time of each operation to a time equal to or a multiple of a cycle, which is achieved by appropriately dividing the technological process into operations or duplicating equipment to obtain the required performance.

In order to avoid interruptions in the work of the production line at the workplace, inter-operational stocks (reserves) of blanks or parts are provided. Backlogs ensure the continuity of production in the event of an unforeseen stoppage of individual equipment.

The in-line organization of production provides a significant reduction in the technological cycle, interoperational backlogs and work in progress, the possibility of using high-performance equipment and a sharp decrease in the labor intensity and cost of products, ease of planning and production management, and the possibility of complex automation of production processes. With flow methods of work, working capital is reduced and the turnover of funds invested in production is significantly increased.

Mass production It is characterized by a limited range of products manufactured in periodically repeated batches and a large output.

In large-scale production, special-purpose equipment and modular machines are widely used. The equipment is located not according to the types of machine tools, but according to the manufactured items and, in some cases, in accordance with the technological process being performed.

Medium series production occupies an intermediate position between large-scale and small-scale production. The batch size in mass production is influenced by the annual production of products, the duration of the processing and setup process. technological equipment. In small-scale production, the batch size is usually several units, in medium-scale production - several tens, in large-scale production - several hundred parts. In electrical engineering and apparatus building, the word "series" has two meanings that should be distinguished: a number of machines of increasing power of the same purpose and the number of machines or devices of the same type simultaneously launched into production. Small-scale production in its technological features is approaching a single one.

Single production characterized by a wide range of manufactured products and a small volume of their output. A characteristic feature of unit production is the implementation of various operations at the workplace. Single-piece production - machines and devices that are manufactured according to individual orders, providing for the fulfillment of special requirements. They also include prototypes.

In unit production, electrical machines and devices of a wide range are produced in relatively small quantities and often in a single copy, so it must be universal and flexible to perform various tasks. In single production, quick-change equipment is used, which allows you to switch from the manufacture of one product to another with minimal loss of time. Such equipment includes machines with program management, computer-controlled automated warehouses, flexible automated cells, sections, etc.

Universal equipment in single production is used only at enterprises built earlier.

Some technological methods that have arisen in mass production are used not only in mass production, but also in single production. This is facilitated by the unification and standardization of products, the specialization of production.

The assembly of electrical machines and apparatus is the final technological process in which individual parts and assembly units are connected into ready product. The main organizational forms of assembly are stationary and mobile.

For stationary assembly the product is completely assembled at one workplace. All parts and assemblies required for assembly are delivered to workplace. This assembly is used in single and serial production and is performed in a concentrated or differentiated way. With the concentrated method, the assembly process is not divided into operations and the entire assembly (from beginning to end) is performed by a worker or a team, and with a differentiated method, the assembly process is divided into operations, each of which is performed by a worker or a team.

With mobile assembly the product is moved from one workplace to another. Workplaces are equipped with the necessary assembly tools and fixtures; on each of them, one operation is performed. The movable form of assembly is used in large-scale and mass production and is carried out only in a differentiated way. This form of assembly is more progressive, since it allows assemblers to specialize in certain operations, resulting in increased labor productivity.

During the production process, the assembly object must sequentially move from one workplace to another along the stream (such movement of the assembled product is usually carried out by conveyors). The continuity of the process during in-line assembly is achieved due to the equality or multiplicity of the execution time of operations at all workplaces of the assembly line, i.e., the duration of any assembly operation on the assembly line must be equal to or a multiple of the release cycle.

The assembly cycle on the conveyor is the planning beginning for organizing the work of not only the assembly, but also all the procurement and auxiliary workshops of the plant.

With a wide range and small quantities of manufactured products frequent reconfiguration of equipment is required, which reduces its performance. To reduce the complexity of manufactured products in last years on the basis of automated equipment and electronics, flexible automated production systems (GAPS) are being developed that make it possible to manufacture individual parts and products of various designs without reconfiguring equipment. The number of products manufactured at the GAPS is set during its development.

Depending on the designs and overall dimensions of electrical machines and apparatuses, various technological assembly processes . The choice of the assembly process, the sequence of operations and equipment is determined by the design, output volume and degree of their unification, as well as the specific conditions available at the plant.

1. Rationale for the choice of workpiece

2. Development of the part processing route

3. Selection of technological equipment and tools

4. Determination of intermediate allowances, tolerances and dimensions

4.1 Tabular method on all surfaces

4.2 Analytical method per transition or per operation

5. Purpose of cutting conditions

5.1 Assignment of cutting conditions by the analytical method for one operation

5.2 Tabular method for other operations

6. The layout of the machine tool for one of the machining operations

7. Calculation of the fixture for the accuracy of machining

Literature

1. Rationale for the choice of workpiece

The optimal method for obtaining a workpiece is selected depending on a number of factors: the material of the part, technical requirements by its manufacture, volume and serial production, the shape of the surfaces and the dimensions of the parts. The method of obtaining the workpiece, providing manufacturability and minimum cost is considered optimal.

In mechanical engineering, the following methods are most widely used to obtain blanks:

pressure treatment of metals;

combinations of these methods.

Each of the above methods contains a large number of ways to obtain blanks.

As a method of obtaining a workpiece, we accept metal forming by pressure. The choice is justified by the fact that the material of the part is 40X structural steel. An additional factor determining the choice of a workpiece is the complexity of the configuration of the part and the type of production (we conditionally assume that the part is manufactured in mass production. We accept stamping on horizontal forging machines.

This type of stamping makes it possible to obtain workpieces with a minimum weight of 0.1 kg, 17-18 accuracy grades with a roughness of 160-320 microns in small-scale production.

workpiece engineering route detail

2. Development of the part processing route

Part processing route:

Operation 005. Procurement. Stamping on CGSHP.

Preparatory shop.

Operation 010. Milling.

Drilling-milling-boring machine 2254VMF4.

Mill the plane, keeping dimension 7.

2. Drill 2 holes D 12.5.

Countersink hole D 26.1.

Countersink hole D32.

Countersink hole D35.6.

Ream hole D36.

Countersink chamfer 0.5 x 45 0.

Operation 015. Turning.

Screw-cutting 16K20.

Cut the end, keeping the size 152.

2. Sharpen surface D37, maintaining size 116.

Sharpen 2 bevels 2 x 45 0.

Cut thread M30x2.

Operation 020. Milling

Vertical milling 6P11.

Mill the surface keeping dimensions 20 and 94.

Operation 025. Vertical drilling.

Vertical drilling 2H125.

Set 1.

Drill 2 holes D9.

2. Drilled a hole D8.5.

Cut thread K1/8 / .

Set 2.

Drill hole D21.

Drill hole D29.

Operation 030 Locksmith.

Blunt sharp edges.

Operation 035. Technical control.

3. Selection of technological equipment and tools

For the manufacture of the "Tip" part, we select the following machines

1. CNC drilling-milling-boring machine with tool magazine 2254VMF4;

2. Screw-cutting lathe 16K20;

Vertical milling machine 6P11;

Vertical drilling machine 2H125.

We use a 4-jaw chuck for turning operations, and special devices for other operations.

In the manufacture of this part, the following cutting tool is used:

Face milling cutter with mechanical fastening of multifaceted inserts: milling cutter 2214-0386 GOST 26595-85 Z = 8, D = 100 mm.

Twist drill with a tapered shank of normal accuracy, diameter D = 9 mm. with a normal shank, accuracy class B. Designation: 2301-0023 GOST 10903-77.

Twist drill with a tapered shank of normal accuracy, diameter D = 12.5 mm. with a normal shank, accuracy class B. Designation: 2301-0040 GOST 10903-77.

Twist drill with a tapered shank of normal accuracy, diameter D = 21 mm. with a normal shank, accuracy class B. Designation: 2301-0073 GOST 10903-77.

Twist drill with a tapered shank of normal accuracy, diameter D = 29 mm. with a normal shank, accuracy class B. Designation: 2301-0100 GOST 10903-77.

One-piece countersink with a conical shank made of high-speed steel, diameter D = 26 mm. 286 mm long for through hole machining. Designation: 2323-2596 GOST 12489-71.

One-piece countersink with a conical shank made of high-speed steel, diameter D = 32 mm. 334 mm long. for blind hole machining. Designation: 2323-0555 GOST 12489-71.

One-piece countersink with a tapered shank made of high-speed steel, diameter D = 35.6 mm. 334 mm long. for blind hole machining. Designation: 2323-0558 GOST 12489-71.

One-piece machine reamer with a tapered shank D36 mm. 325 mm long. Designation: 2363-3502 GOST 1672-82.

Conical countersink type 10, diameter D = 80 mm. with an angle at the top of 90. Designation: Countersink 2353-0126 GOST 14953-80.

Cutter right through thrust bent with an angle in the plan 90 o type 1, section 20 x 12. Designation: Cutter 2101-0565 GOST 18870-73.

Threaded turning tool with high-speed steel blade for metric thread with step 3 type 1, section 20 x 12.

Designation: 2660-2503 2 GOST 18876-73.

Machine tap 2621-1509 GOST 3266-81.

To control the dimensions of this part, we use the following measuring tool:

Caliper ШЦ-I-125-0.1 GOST 166-89;

Caliper ШЦ-II-400-0.05 GOST 166-89.

To control the size of the hole D36, we use a plug gauge.

A set of roughness samples 0.2 - 0.8 ShTsV GOST 9378 - 93.

4. Determination of intermediate allowances, tolerances and dimensions

4.1 Tabular method on all surfaces

The necessary allowances and tolerances for the machined surfaces are selected according to GOST 1855-55.

Machining allowances for the part "Tip"

Size, mm.	Roughness, µm.	Allowance, mm.	Size tolerance, mm	Size with allowance, mm.
		Roughing 8 Medium 1.5 Finishing 0.5
		Roughing 3.0 Finishing 3.0

4.2 Analytical method per transition or per operation

Calculation of allowances by the analytical method is carried out for the surface Roughness Ra5.

The technological route of hole processing consists of countersinking, roughing and finishing reaming

The technological route of hole processing consists of countersinking and rough, finishing reaming.

Allowances are calculated according to the following formula:

where R is the height of the profile irregularities at the previous transition;

Depth of the defective layer at the previous transition;

Total deviations of the surface location (deviations from parallelism, perpendicularity, coaxiality, symmetry, intersection of axes, positional) at the previous transition;

Installation error on the transition being performed.

The height of microroughness R and the depth of the defective layer for each transition are found in the table of the methodological manual.

The total value characterizing the surface quality of forged blanks is 800 µm. R= 100 µm; = 100 µm; R= 20 µm; = 20 µm;

The total value of spatial deviations of the axis of the hole being machined relative to the center axis is determined by the formula:

, (2)

where is the displacement of the treated surface relative to the surface used as a technological base for reaming holes, microns

(3)

where is a size tolerance of 20 mm. = 1200 µm.

Dimensional tolerance 156.2 mm. = 1600 mm.

The amount of warping of the hole should be taken into account both in the diametrical and in the axial section.

where is the value of specific warpage for forgings. = 0.7, and L is the diameter and length of the hole being machined. = 20 mm, L = 156.2 mm.

µm.

The value of the residual spatial deviation after countersinking:

P 2 \u003d 0.05 P \u003d 0.05 1006 \u003d 50 microns.

The value of the residual spatial deviation after rough development:

P 3 \u003d 0.04 P \u003d 0.005 1006 \u003d 4 microns.

The value of the residual spatial deviation after finishing reaming:

P 4 \u003d 0.002 P \u003d 0.002 1006 \u003d 2 microns.

Residual error for rough reaming:

0.05 ∙ 150 = 7 µm.

Residual error for fine reaming:

0.04 ∙ 150 = 6 µm.

We calculate the minimum values ​​of interoperational allowances: reaming.

Draft deployment:

Net Deployment:

The largest limit size for transitions is determined by successive subtraction from the drawing size of the minimum allowance of each technological transition.

The largest diameter of the part: d P4 = 36.25 mm.

For fine reaming: d P3 = 36.25 - 0.094 = 36.156 mm.

For draft deployment: d P2 = 35.156 - 0.501 = 35.655 mm.

For reaming:

P1 \u003d 35.655 - 3.63 \u003d 32.025 mm.

The values ​​of the tolerances of each technological transition and workpiece are taken from the tables in accordance with the quality of the processing method used.

Quality after finishing deployment: ;

Quality after rough deployment: H12;

Quality after reaming: H14;

Workpiece quality: .

The smallest limit dimensions are determined by subtracting tolerances from the largest limit dimensions:

MIN4 = 36.25 - 0.023 = 36.02 mm. MIN3 = 36.156 - 0.25 = 35.906 mm. MIN2 = 35.655 - 0.62 = 35.035 mm. MIN1 = 32.025 - 1.2 = 30.825 mm.

Maximum limit values ​​of allowances Z PR. MAX are equal to the difference of the smallest limit sizes. And the minimum values ​​of Z PR. MIN, respectively, the difference between the largest limit sizes of the previous and executed transitions.

ETC. MIN3 = 35.655 - 32.025 = 3.63 mm. ETC. MIN2 = 36.156 - 35.655 = 0.501 mm. ETC. MIN1 = 36.25 - 36.156 = 0.094 mm. ETC. MAX3 = 35.035 - 30.825 = 4.21 mm. ETC. MAX2 = 35.906 - 35.035 = 0.871 mm. ETC. MAX1 = 36.02 - 35.906 = 0.114 mm.

General allowances Z O. MAX and Z O. MIN are determined by summing up the intermediate allowances.

A. MAX \u003d 4.21 + 0.871 + 0.114 \u003d 5.195 mm. A. MIN \u003d 3.63 + 0.501 + 0.094 \u003d 4.221 mm.

The obtained data is summarized in the resulting table.

Technological transitions of surface treatment Elements of allowance

Estimated allowance, microns. Tolerance δ, µmLimit size, mm. Limit values ​​of allowances, microns
blank
Countersinking
Draft deployment
Fine reaming

Finally we get the dimensions:

Blanks: d ZAG. =;

After reaming: d 2 = 35.035 +0.62 mm.

After rough deployment: d 3 = 35.906 +0.25 mm.

After fine reaming: d 4 = mm.

The diameters of the cutting tools are shown in point 3.

5. Purpose of cutting conditions

5.1 Assignment of cutting conditions by the analytical method for one operation

milling operation. Mill the plane, maintaining a size of 7 mm.

a) Depth of cut. When milling with a face mill, the depth of cut is determined in the direction parallel to the axis of the cutter and is equal to the machining allowance. t = 2.1 mm.

b) The milling width is determined in the direction perpendicular to the cutter axis. H = 68 mm.

c) submission. When milling, a distinction is made between feed per tooth, feed per revolution, and feed per minute.

where n is the rotational speed of the cutter, rpm; is the number of teeth of the cutter.

With machine power N = 6.3 kW S = 0.14.0.28 mm/tooth.

We accept S = 0.18 mm / tooth.

mm/rev.

c) Cutting speed.

(6)

Where T is the period of resistance. In this case T = 180 min. - general correction factor

The coefficient taking into account the processed material.

nV (8) HB = 170; nV = 1.25 (1; p. 262; table 2)

1,25 =1,15

Factor taking into account the material of the tool; = 1

(1; p.263; tab.5)

Coefficient taking into account the state of the surface of the workpiece; = 0.8 (1; p. 263; table 6)

V = 445; Q = 0.2; x = 0.15; y=0.35; u = 0.2; p=0; m = 0.32 (1; p.288; tab.39)

m/min

d) Spindle speed.

(9) n rpm

We correct according to the machine passport: n = 400 rpm.

mm/min

e) Actual cutting speed

m/min.

e) District power.

(11)

where n = 0.3 (1; p.264; tab.) 0.3 = 0.97

With P=54.5; X = 0.9; Y = 0.74; U=1; Q=1; w = 0.

5.2 Tabular method for other operations

The assignment of cutting modes by the tabular method is carried out according to the reference book of metal cutting modes. The resulting data is entered into the resulting table.

Cutting conditions for all surfaces.

Name of operation and transition	Overall dimension		Cutting depth, mm	Submission, mm/rev. (mm/min)	Cutting speed, m/min	Spindle speed, rpm.
Operation 010 Milling
1. Mill the surface keeping dimension 7
2. Drill 2 holes 12,512,576,250,0815,7400
3. Countersink hole 26.1. 26.11523.050.0820.49250
4. Countersink hole 32. 321122,950,0825,12250
5. Countersink hole 35,635,6921,80,0817,89160
7. Countersink chamfer 0.5 x 45 o
Operation 015 Turning
1. Cut the end, keeping the size 152
2. Sharpen surface D37, keeping size 116
3. Cut thread M30x2
Operation 020 Milling
Mill the surface keeping dimensions 20 and 94
Operation 025 Vertical drilling
1. Drill 2 holes 995,54,50,0811,3400 We design a machine fixture for vertical drilling and vertical milling machines. The device is a plate (pos. 1.) on which 2 prisms (pos. 10) are mounted using pins (pos. 8) and screws (pos. 7). On the side of one of the prisms there is a stop (pos.3) with a finger located in it, which serves to base the workpiece. The clamping of the part is provided by the bar (pos. 3), which rotates freely around the screw (pos. 5) with one edge, and the screw enters its other edge, which has the shape of a slot, followed by clamping with a nut (pos. 12). To fix the fixture on the machine table, 2 dowels (pos.13) are made and mounted in the body of the plate, which serve to center the fixture. Transportation is carried out manually. 7. Calculation of the fixture for the accuracy of machining When calculating the accuracy of the fixture, it is necessary to determine the permissible error ε = 0.3…0.5; accept = 0.3; The remaining values ​​of the formula are a set of errors defined below. Based error e b occurs when the measurement and technological bases do not match. When machining a hole, the locating error is zero. The workpiece clamping error ε C occurs as a result of the clamping forces. Fixing error when using manual screw clamps is 25 µm. The installation error of the fixture on the machine depends on the gaps between the connecting elements of the fixture and the machine, as well as on the inaccuracy in the manufacture of the connecting elements. It is equal to the gap between the T-slot of the table and the setting element. In the fixture used, the size of the groove width is 18H7 mm. The size of the dowel is 18h6. Limit deviations U sizes B.A. Kuzmin, Yu.E. Abramenko, M.A. Kudryavtsev, V.N. Evseev, V.N. Kuzmintsev; Technology of metals and construction materials; - M.: "Engineering"; 2003 A.F. Gorbatsevich, V.A. Shkred; Course design on engineering technology; - M.: "Engineering"; 1995 V.D. Myagkov; Tolerances and landings. Directory; - M.: "Engineering"; 2002 IN AND. Yakovlev; General machine-building standards for cutting conditions; 2nd edition; - M.: "Engineering"; 2000 V.M. Vinogradov; Engineering technology: introduction to the specialty; - M.: "Academy"; 2006;

Single productioncharacterized by the production of a wide range of machines in small quantities (often units), so it is a universal non-flow. The production of machines is either not repeated at all, or is repeated at indefinite intervals. Characteristic features single production: performance of various operations at workplaces; the use in the assembly process of basically normal cutting, measuring and auxiliary tools and universal devices; a large number of fitting works. Due to the variety of assembly work in a single production, it is difficult to specialize fitters, therefore, highly qualified fitters mainly work in assembly shops. Single production is typical for heavy engineering, the products of which are large hydraulic turbines, unique metal-cutting machines, rolling mills, walking excavators and other equipment.

Mass production- the manufacture of machines not in units, but in series, regularly repeating (at regular intervals). A series is a task for the production of identical cars for a year, quarter, month. With serial production in the assembly shop, it is possible to assemble the same machines (products) for a long period of time, which makes it possible to much better equip the assembly process with special tools, fixtures and equipment. In the conditions of serial production, the technological process of assembling machines is built on the principle of parallel-sequential execution of operations. Complex operations are divided into simpler ones, the general assembly of machines is divided into a nodal assembly. The division of assembly into central and general assembly, the production of the same machines for a long period, along with a decrease in the number of fitting works, makes it possible to organize the specialization of workers and, consequently, to use fitters with a narrower specialization than with a single assembly. This greatly improves productivity. Depending on the size of the series (batch) of machines, small-scale production is distinguished, which has certain similarities with single-piece production, and large-scale production, which has many of the distinctive features of mass production.

Mass productioncharacterized by the release of a large number of identical machines (products) over a long (several years) time, for example, bicycles, cars, etc. The assembly process in mass production is divided into simple assembly operations. This allows each workplace to perform one, constantly recurring operation and, to an even greater extent than in mass production, to narrow the specialization of the worker and simplify the equipment, arranging it along the technological process in the form of production lines. On each line, a separate part is processed or a nodal assembly of the product is made. Mass production makes it possible to implement the principle of complete interchangeability, which means that any part can be put on the machine without any fitting work; in the same way, a part removed from a machine of a given model should fit without any adjustment to any of the same machine.

Mass production is in-line. It is often referred to as mass flow. With the flow method of work, the assembled products (assembly units) are moved from one workplace to another manually (on trolleys, roller tables, etc.) or by a mechanized transport device of continuous or periodic action (conveyor or conveyor).

PRODUCTION ORGANIZATION PRACTICE

FEATURES OF DESIGN AND ORGANIZATION OF GROUP PRODUCTION IN ENGINEERING M.I. Bukhalkov, Doctor of Economics sciences, professor,

M.A. Kuzmin, postgraduate student,

V.V. Pavlov, Ph.D. economy Sciences, Associate Professor Samara State Technical University, Samara

The scientific foundations of the organization of group production at the enterprises of the machine-building complex are considered, practical advice for the design and scheduling of group production lines

Group production is a progressive flexible form of organization of discontinuous production processes at engineering enterprises, based on the subject specialization of shops and sections and the standard unification of technological processes. Depending on volume market demand on manufactured products, the direction of specialization existing at the enterprise and the achieved level of technological unification, it is customary to distinguish six main forms of group organization of production processes. With a detailed specialization of production using a single or standard form of organization of technological processes, three primary forms of group production can take place:

Detailed specialized workshops of the enterprise;

Detailed specialized sections of the workshop;

Multiproduct group production lines with changeover of machines.

With a detailed specialization of production, combined with the use of a group form of organization of technological processes, the following secondary forms of group production are created:

Detail-group mechanical assembly shops;

Detail-group production sites;

Group production lines with reconfigurable machines.

Secondary forms of organization of group production are based on the widespread use of high-performance equipment, quick-adjustable technological equipment, machine tools with numerical control, special machining centers and specialized machine tools and other technological means of mechanization and automation of the main and auxiliary production processes. As domestic best practices testify, group production at engineering enterprises, created on the basis of a constructive classification of manufactured products, unification of technological processes

owls and detail-group specialization of production units, contributes to the market-specific conditions of single, small-scale and serial types of production, the widespread use of such principles of rational organization inherent in mass production production process, as the specialization of jobs, continuity, rhythm, direct flow, etc. Taking into account the degree of completeness of the use of these principles, group production of products can function at an enterprise with various organizational forms and types of production.

In single, small-scale and serial types of production, it is advisable to use the methods of organizing group processes in the manufacture of various parts, assembly of products and repair of equipment in the main and auxiliary shops. In large-scale and mass production, group forms of its organization are recommended to be used when high level specialization and the coefficient of fixing operations for the workplace, equal to or exceeding two performed detail operations per month, as well as with an insignificant production cycle for the manufacture of parts.

The coefficient of specialization or consolidation of jobs in various divisions of machine-building enterprises depends on a combination of two organizational indicators - the volume of output and the labor intensity of products, which largely determine the technological or subject forms of specialization of shops and sections, production and organizational structure enterprises, as well as methods and forms of organization of group production. Gradual transition from technological form specialization to the detail-group is considered one of the important progressive directions in improving the organization of modern engineering production.

The highest form of development of group production is, under market conditions, the introduction, with appropriate output volumes, of flexible, quickly adjustable production lines for machining parts and assembling products.

The organization of group production includes next complex design work that ensure the creation and functioning of specialized units:

Analysis of the range of manufactured products and the basic conditions for their production;

Classification and coding of machined parts;

Grouping parts according to accepted classification criteria;

Unification of parts and testing them for manufacturability;

Analysis of existing technological processes and development of group ones;

Calculation of the complexity of the implementation of group technological processes;

Determination of the composition of production units;

Designing the organization of group production of products;

Determination of the required technological equipment in the project;

Acquisition of the necessary means of technological equipment;

Pilot testing and implementation of group production organization.

The basis for the organization of group production, according to S.P. Mitrofanov, is the unification of the designs of manufactured products and technological processes for their manufacture. The most important organizational areas of constructive and technological unification in machine-building production, with a decrease in market demand for products, were the development of standard technological processes and the use of group methods for processing parts. Typical technological processes are created for the manufacture of the same type or standardized parts and are used mainly in large-scale and mass production. Group technological processes are developed into groups of parts similar in design or other characteristics and are used in single, small-scale and mass production.

The typification of processing methods is based on the classification of parts and their surfaces. The classification of parts and technological processes is based on the class-group-type scheme. A class is a set of parts of a certain configuration, characterized by a common design forms and technological processes, for example, shafts, bushings, gears, etc. Each class is divided into subclasses and groups, each group into subgroups and types. A group is a set of parts that are combined during processing by a common equipment, tooling, adjustment and technological or operational process. When creating groups, the dimensions of the part, geometric shape, generality are taken into account.

surfaces to be processed, the required quality of accuracy, surface roughness, uniformity of workpieces, serial production, process efficiency and many other factors. The group serves as an intermediate link in the classification of parts, final goal which consists in establishing types. A type is a set of similar parts that have a common technological process in specific production conditions.

Typical technological processes are intended for the production of standard and standardized parts, assembling units and complex products. There are two methods of typification of technological processes used at mechanical engineering enterprises. The first way is to carry out such a classification of parts, as a result of which the number of existing constructive types products and for each of them a general technological process is drawn up. The second way is to establish a number of technological processing methods related to individual parts or their characteristic surfaces that have structural features of similarity - the basis for building typical processes. The construction of standard processes is carried out on the constructive similarity or similarity of the workpieces and their surfaces, and not on the commonality of the means of production and tools of labor - machine tools, fixtures, tools. Typical processes specific to this particular enterprise should cover all parts that have the same processing route, the same type of machines, the equipment used, as well as cutting and measuring tools. Such processes are usually developed with detailed description route technology and compilation technological maps for the corresponding types of parts, which contain a list of specific operations, equipment and tools, processing modes, time standards and other organizational and technical indicators.

Group technological processes are developed for types of products that are homogeneous in terms of one or another design and technological features using a unified production technology and quick-change tooling. The group processing method is directly related to the unification of the design of machines and their elements, as well as to the organization of their production. The higher the level of unification of technology, the correspondingly higher the level of specialization of production and, consequently, the more perfect the forms of its organization in the enterprise. The most important organizational prerequisites for the use of group methods in machine-building production are the following:

Correct classification and grouping of manufactured parts, work performed and designed technological processes;

Selection and design of group fixtures and other technological equipment for the implementation of the adopted technology;

Specialization and modernization of technological equipment in order to increase the efficiency of its use;

Implementation of group flow and automatic lines for the production of parts.

The group method, as the basis for the unification of technological processes and means of equipping them, helps to reduce their number for the manufacture of parts of the same type and at the same time expands the use of progressive technology for the production of a large range of products. At machine-building enterprises, it is customary to distinguish between two main

ny directions of technological unification: typification of technological processes and a group method of processing parts. Both of these completely independent approaches, complementary to the system solution at the enterprise of common technological and organizational problems, are presented in Fig. 1. Their fundamental difference lies in the fact that standard processes are characterized by a common sequence and content of operations (transitions) when processing a typical group of parts, and group technology is characterized by a common equipment and tooling when performing individual operations or in the complete manufacture of a group of different types of parts.

Unification of technological processes

Typification of technological processes

Batch processing methods

Rice. 1. Scheme of unification of technological processes

Group methods for organizing technological processes can be based on different approaches to the classification of parts and methods for their processing. The task of any classification is to establish the defining features, objects of labor necessary for the correct grouping of designed objects or to identify their main properties and characteristic features. Various designs of machines and devices, types of products and parts have a large number of identical constructive, technological, organizational and a number of other common features. Group processes at engineering enterprises are usually classified according to the following most important features:

According to the structural and technological similarity of manufactured parts, according to which groups of rollers, bushings, spindles, splined shafts, gears, etc. serve as typical sets;

Based on the elementary surfaces of the workpieces, which allow you to choose the necessary method for changing their shapes and sizes and make up from their combination the total technological process of processing any part containing certain

surfaces, for example, round, flat, as well as grooves, holes, etc.;

According to the types of technological equipment used, including the corresponding types and models of metalworking machines, for example, turning, drilling, milling, grinding and

By the unity of the technological equipment used in various operations and types of equipment, for example, by the commonality of methods for fastening a part, setting up equipment, etc.

In addition, in all directions of the classification of group processing processes, such features as the purpose of the part, the complexity of the design, the accuracy and roughness of surfaces, the similarity of technological routes, the volume of output, methods of operational control of production, the composition of organizational and planning standards, etc. are taken into account. apply a wide variety of signs of classification of processed products, which confirms the flexibility of group production and the need for its use in conditions of market uncertainty in demand for goods and services.

The system of group classification of products and processes developed by S.P. Mitrofanov is based on the commonality of the design of parts, processing technology, equipment used, methods of setting up machine tools, and tooling. Basically, the workpieces are divided into three characteristic groups:

1) parts that have a complete processing cycle on one type of equipment, such as procurement processes, metal cutting, thermal operations, finishing work, etc.;

2) products that have a common multi-operational process performed on various types of technological equipment in the order of the sequence of operations using group equipment;

3) groups of parts that have a common technological processing route, carried out on different types of equipment in compliance with the principle of direct flow of the movement of processed objects.

Grouping of parts can also be carried out according to the degree of unification of processing conditions at the enterprise. In this case, it is recommended to distinguish between two ways of grouping parts:

Parts with unified processing processes, when their combination is carried out either within one type of technological process performed on equipment of the same type, or within several types of processing on equipment of various types according to the commonality of technological routes;

Parts with partial unification of processing processes, when grouping occurs either for several different products according to one technological operation, or for several adjacent operations of one part along the current technological route.

The grouping of parts in all cases should cover the range of actually manufactured parts of a certain design. If necessary, you can create complex or conditional parts that have all the geometric elements of the parts of this group. A real part can also be complex, having all the main characteristics of the most complex part in this group. The selected complex representative part serves as the basis for the development of group technology and group equipment, which are a set of fixtures and tools and ensure the processing of all parts of this group with minor adjustments to the equipment. The technological process drawn up for a complex part should ensure the manufacture of any part of this group in full compliance with the customer's requirements for the quality level and deadlines. Each group technological process consists of a number of provided group technological operations for processing or assembling a product.

A group technological operation is a common part of the technical process for a given group of parts of different design characteristics, which is performed with a certain group equipment on the appropriate equipment. A group operation covers as many part operations as there are parts of different types included in this group. Detail-operation is a differentiated composition of technological transitions in the processing of a specific part of a certain group, for which a group operation has been developed. The set of group operations form a group technological process that provides processing of various parts of one or several groups along a common technological route. With a group technological route, some parts or their groups may not be processed at each operation, i.e. skip individual machines or operations. Therefore, when forming groups of parts with a common technological process, it is necessary to take into account the volume of production of individual parts: the labor intensity of the performed part operations should ensure the normal loading of machines and operator workers at each operation.

Technological routes that do not have some operations or transitions must provide not only the principle of direct flow in space, but also the principle of proportionality of equipment operation in time. On fig. Figure 2 shows a scheme for selecting parts and a schedule for the operation of a group production line, on which five types of parts are processed on five operations (machines) during one work shift lasting 480 minutes. In the above diagram, the processing route for each part is shown as a solid line with corners indicating the presence of a technological operation. Above the line is the piece time for the operation, below the line - the cycle time for processing the batch of each part. So, part B with a labor input of 15 minutes is manufactured in the amount of 30 units at the first, third and fifth operations, the piece time for which is 6, 4 and 5 minutes, respectively. In this case, the estimated cycle time for processing the entire batch of parts B at the first operation will be:

Tobr \u003d N Tsht \u003d 30 6 \u003d 180 min / batch

where N is the batch size of parts, pcs.;

Tsht - piece time for the first operation, min / piece.

The processing time of a batch of parts at individual operations and the total time of passage of each batch of products along the entire technological route is calculated in a similar way using the above formula. Equipment load factors can be found as the ratio of the total processing time of all groups of parts for individual operations to the duration of the work shift. This indicator when processing a group of parts on the first machine or operation will be equal to:

Tcm - duration of the work shift, min.

where Y Tobr - the total processing time of all parts on a given operation (machine), min;

Parts group Calculated indicators Number of operation (machine)

Tsht Np-Tsht 1 2 3 4 5

Part A 30 12 360 /\ 3 ✓Ch 2 ✓■44 /\ 3

Detail B 30 15 450 A6 ✓P 4 ✓P 5

Part H 40 18 720 ^2

80" 160 160 160 160

Part D 26 12 312 "W5 /\ 3 ✓W4

Detail D 18 8 144 y-Ch6 ^h 2

Parts group A+B+C+D+D I N IT / -< шт I N Тшт Б+В+Г А+В+Д А+Б+В+Г А+В+Г А+Б+В+Д

Totals 144 65 1986 390 358 418 384 436

Machine load factor - - 0.83 0.81 0.74 0.87 0.80 0.91

Rice. 2. Working schedule of the group production line

Equipment utilization factors are important organizational indicators of the effectiveness of the implementation of group production. In the given example, their individual value for individual transactions is in the range from 0.74 to 0.91, with an average value in the area equal to 0.83. These coefficients testify to the high loading and efficiency of the use of technological equipment in the project, as well as the correct selection of parts in this section of group production.

At enterprises, equipment load factors largely depend on the ratio of the calculated (design) and accepted (established) number of jobs (machines), as well as on the number and labor intensity of the parts being processed.

In group production, the required number of jobs can be calculated for each individual operation or for the entire production unit as a whole based on the ratio of the corresponding machine-tool intensity of the operation or section to the fund of equipment operation time. V general case the number of jobs required to fulfill existing orders is determined by the following formula:

where Сtot is the total amount of equipment in the group section, pcs.;

total design machine capacity

production orders on the site, machine-hour;

Fd is the actual fund of equipment operation time, hour.

The annual fund of working time of a piece of equipment with a two-shift operation is approximately 4000 hours, the monthly fund with one-shift work is 175, the weekly fund is 40 hours.

The calculated number of machines in the group section is distributed by types and models in accordance with the labor intensity (machine-intensiveness) of the work performed on orders. The machines at the production site are located taking into account the need to comply with the scheme of movement of parts along a previously developed technological route. Depending on the accepted form of organization of group production on the site, various methods can be used. production schemes location of technological equipment: point, linear, cellular, technological, etc. In fig. 3 shows the most common options for planning technological equipment in group production in American firms.

dotted

Technological

Linear

cellular

Rice. 3. Scheme of layout of equipment on the site

As can be seen, group production contributes to saving production space and working time when organizing the production of a wide range of goods and services at engineering enterprises according to the orders of the main consumers of products. Improving the organization of group production can be an important factor modernization of domestic industrial enterprises

Thus, the organization of group production is in market conditions one of the important directions creation and operation of multi-product flexible production systems which take into account changes in market demand for products in the course of production and allow the production of high quality goods and services with the fullest use of the production resources available at each enterprise.

In mechanical engineering, there are three main types of production: single (individual), serial and mass, and two methods of work: in-line and non-in-line.

Each type of production has its own methods of its preparation and planning. They also differ in the form of labor organization, the degree of detail in the development of technological processes, the organization of repairs, etc.

single(individual) is such a production in which the product is performed in one or more copies; as a rule, these products are almost never re-manufactured. Such production exists in heavy and chemical engineering, shipbuilding, etc.

In unit production, universal machines, universal fixtures and normal tools are used to process a variety of parts. Special tools and special devices are almost never used, since their production requires high costs. Installation and alignment of workpieces on machines are carried out using markings and universal measuring instruments. The accuracy of part manufacturing is also controlled by universal measuring instruments- caliper tools, micrometers, indicators, etc.

The qualification of workers in single production is usually high, but labor productivity is much lower, and the cost of a part is higher than in series and mass production.

In mechanical engineering, the most widely used serial production in which products are produced in batches or series of various sizes. Depending on the size of the parties and the frequency of repetition during the year, they are distinguished small-scale , medium series and large-scale production. The main difference between mass production and single production is a less diverse range of products manufactured at each workplace, and the periodic repetition of batches of products.

In mass production, the percentage of universal machines decreases, but the share of specialized and special machines increases. Machine tools such as revolving, multi-cutting lathes are widely used, and in large-scale production, semi-automatic and automatic lathes are also used. Specialization of machines allows the use of specialized and special fixtures and cutting tool, providing an increase in labor productivity and a decrease in the cost of products. Limit gauges are often used to control the accuracy of machining parts.

Serial production is characterized by a differentiated technological process for manufacturing parts. It is divided into a number of small operations performed on various machines. Operations requiring more than one machine are not usually found in mass production. The qualification of workers is much lower than in the individual, and labor productivity is higher.

Mass production is common in all industries.

Mass production is characterized by a large number of manufactured products, which allows each workplace to perform only one, constantly repeating operation.

In mass production, highly specialized automatic machines, special fixtures and cutting tools are widely used. The dimensions of the manufactured part are controlled using special devices, and often during processing. Depending on the equipment used, the technological process of machining is divided into a number of small operations carried out on separate special machines, or it involves the implementation of many transitions on multi-spindle machines, multi-position modular machines, etc.

Mass production provides the most economical processing of products. This type of production is widespread in the automotive and tractor industries, in factories producing agricultural equipment, motorcycles and a number of other products. The type of production depends on the given program and the labor intensity of manufacturing the product and is determined by the production cycle and serialization coefficient.

Under exhaust stroke is understood as the time interval between the release of two successive machines and their assembly units - parts or blanks. When designing technological processes of mechanical processing, the value of the release cycle is determined by the formula:

where F d- the actual annual fund of equipment operation time in one

shift, in hours; m- the number of work shifts; N- the annual program for the production of parts, in pcs. The serialization coefficient shows the number of different operations assigned to one machine and is calculated by the formula:

where τ in- tact of release of details; T pcs- the average piece time for the operations of processing the part.

To determine T pieces, it is necessary to make an aggregated calculation or take the time for similar operations performed at the base plants.

for mass production K ser < 2, для крупносерийного xer from 2 to 10, for medium series from 10 to 20 and small series xer >20.

Thus, knowing the value of the production cycle and the serialization coefficient, it is possible to preliminarily determine the type of production.

At in-line In production, machining operations are assigned to certain workplaces, which are located in the order provided for by the technological process, and the workpiece is transferred from one operation to another without significant delays.

non-streaming production is one in which the manufactured parts in the process of processing are in motion with interruptions of various durations, i.e., the processing process is carried out with a changing tact value.