Route technological process of part repair. Technological map Technological map for the repair of a simple part
Routing Is an instruction for completing a task.
Technological maps, drawings, sketches, instruction cards - all this technical documentation, which describes the nature and order of the assignment.
The technological maps indicate the sequence of manufacturing parts, sketches of processing, the tool used, the type and material of the workpiece.
The manufacturing sequence can be detailed and concise. It all depends on the complexity of the part.
In training flow charts, sketches of processing are sometimes shown (see flow chart below).
Working on such cards, students will be able to make products more independently.
In the column "Sequence of processing" indicate operations, transitions, passes.
Operation
Operation is a complete part of the technological process of processing a part, performed at one workplace by one worker or a team.
For example, if a locksmith is tasked with filing the surface of a part with frank and personal files and removing burrs from the edges, this will be one operation.
The indicated processing sketches show technological process making a key. It consists of the following operations: marking, drilling, cutting with a hacksaw, filing and others. Each technological operation includes transitions.
Transition
A transition is a part of an operation performed without changing the tool and without rearranging the workpiece to be machined (on a machine, in a vice, in a fixture).
So, if the surface of the workpiece is processed first with a fist file, and then with a personal file, filing with a fist file is the first transition, and processing with a personal file is the second transition.
The passage, in turn, is divided into passages.
Passage
A walkway is a part of a walkway that encompasses all actions associated with removing one layer of material.
The dismemberment of the operation allows the worker to better adapt to performing simple monotonous work techniques and to use special devices.
"Locksmithing", I. G. Spiridonov,
G.P.Bufetov, V.G. Kopelevich
A part is a part of a machine made from one piece of material (e.g. bolt, nut, gear, lead screw lathe). A knot is a connection of two or more parts. The product is assembled according to assembly drawings. A drawing of such a product, which includes several units, is called assembly, it consists of drawings of each part or unit and depicts an assembly unit (drawing of a single ...
The threads on the rods are depicted along the outer diameter with solid main lines, and along the inner diameter - with solid thin lines. The image of the thread on the screw shaft The main elements of metric threads (external and inner diameters, thread pitch, thread length and angle) you studied in fifth grade. The figure shows some of these elements, but they do not make such inscriptions in the drawings. Carving in ...
You are familiar with the scale designation (M), drawing projections: front, top, side views, - you know the designation of the diameter (0), radius (R) of a circle, metric thread (for example, M10, M6). In working drawings, in addition to front, top, side views, it is sometimes necessary to show the internal shape of a part. The inner shapes of the disc can be shown in views using dashed lines. The image of the disk a - in the figure; ...
Modern production development makes increased demands on infrastructure maintenance industrial enterprises... These include ensuring continuous production process, introduction of constructive and technological improvements finished products, shortening the time for manufacturing products and carrying out repair work, increasing the efficiency of spending the main and working capital enterprises. Systematic analysis manufacturing companies reveals two opposite tendencies: more and more new types of work are being introduced at enterprises, and at the same time the qualifications of personnel are decreasing more and more.
As a result, the bit depth of the tasks performed often exceeds the bit depth of the workers. This directly leads to a decrease in productivity, a deterioration in the quality of work and the occurrence of abnormal situations that can entail not only equipment failure, but also industrial accidents. And if the drop in productivity and quality is fraught with material losses, then the deterioration in the level of safety jeopardizes the activities of the enterprise as a whole.
To ensure compliance with the increased requirements for infrastructure maintenance, enterprises create specialized divisions in their circuit, and also involve specialized organizations to perform certain types of work. But, as practice shows, a simple change is not enough to increase productivity and safety in the production of work. staff structure or hiring contractors. Solving these problems requires the use of a number of special effective instruments, one of which are flow charts that determine the order of performing standardized operations of the technological process.
What does the technological map contain
A technological map is a unified document intended for employees of an enterprise engaged in the repair or maintenance of production equipment. The map contains a list necessary equipment, tools and sets of personal protective equipment, a list of instructions for labor protection. It indicates the sequence, frequency and rules for performing operations, types and quantity Supplies, time norms, material costs, as well as regulatory documents used in assessing the quality of work.
Technological maps are developed in order to systematize and improve the safety of the production process by streamlining the actions of personnel in the process of repair or technological maintenance of equipment. Their implementation also contributes to solving problems of determining and optimizing material and technical costs per unit of product or service.
Benefits of introducing technological maps
The development of technological maps allows the company to obtain the full amount of information necessary for a high-quality and safe organization of the production process, filling the gap in knowledge about innovations in the field of equipment, technology for its repair and maintenance.
As practice shows, the use of technological maps helps to reduce the rate of equipment wear by 15-20%, while the cost of repairs is reduced by 13-14%, and the labor intensity of work - by 16%. Compliance with the instructions set out in the documents ensures the trouble-free operation of the equipment during the entire period between scheduled repairs and significantly reduces the risks of emergency situations and unplanned stoppages of the production process.
In addition, the surveys carried out in the course of preparation make it possible to plan the timing and costs of periodic repair and maintenance work in the future, improve production efficiency and reduce the time required for scheduled repairs.
The presence of a technological map greatly simplifies the preparation of production schedules, preparation of economic planning documentation, training of personnel and systematization of the work of the supply service.
The introduction of technological maps helps to systematically reduce the cost of repair and maintenance of equipment, providing significantly lower costs of funds and resources in comparison with the cost of technical re-equipment and reorganization of the production structure.
Challenge for professionals
Starting the development of technological maps, you must first familiarize yourself in detail with the tasks of the enterprise and its capabilities in terms of equipment, tools, personnel and material and technical supplies. Often, enterprises, in an effort to minimize costs, prefer to entrust this work to full-time technical workers. At the same time, they forget about the importance of a professional approach and familiarity with innovations in the field of industry quality and safety standards, which only a specialized organization can guarantee.
It is often beneficial to outsource the development of flow sheets to outside organizations. having a high level of competence in this area. In particular, it can provide services for the development of technological maps for enterprises of any industry. Preparation and transfer of documentation to the customer can be performed both in standard paper form and using specialized software.
Involvement of our specialists has a number of advantages in comparison with independent development:
- objective and impartial assessment of opportunities and prospects by independent experts;
- access to regularly updated professional bases regulatory documents, equipment, tools and materials;
- regular retraining and training of personnel in connection with the emergence of new technologies and solutions;
- interest of the company's specialists in achieving the result.
An additional advantage of cooperation with our company is our rich practical experience in the field of servicing the infrastructure of industrial enterprises, introducing innovative technologies and modernizing technological processes.
For several years, we have been developing our competencies in cooperation with largest enterprises machine-building, chemical, petrochemical and metallurgical industries. The company's experience allows us to talk about a real reduction in labor costs when using technological maps.
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Introduction
1. General position
2.2 Selection of technological bases
2.5 Calculation of processing modes
Conclusion
Literature
Introduction
valve engine repair defect
In the process of restoring a part, it is possible not only to reduce the cost of repairing machines, but in many cases to improve its quality, since many of the restoration methods significantly strengthen the restored surfaces and increase their wear resistance.
Car repair is of great economic importance. The main sources economic efficiency car repair is the use of the residual resource of their parts. About 70 ... 75% of car parts that have passed the service life before the first overhaul have a residual life and can be reused either without repair or after a slight repair impact.
Improving the quality of car repair while reducing its cost is the main problem of repair production. In the structure of the cost of overhaul of machines, 60 ... 70% of the costs are spent on the purchase of spare parts, which, even in market conditions, remain in short supply when prices rise. The main way to reduce the cost of repairing machines is to reduce the cost of spare parts. This can be partially achieved through careful and competent disassembly of machines and inspection of parts. However, the main reserve is the restoration and reuse of worn-out parts. restoration of worn-out parts, does not exceed 20 ... 60% of the price of a new part. In addition, the restoration of parts is one of the main ways to save material, raw materials and energy resources, the solution environmental issues, since the cost of energy, metals and other materials is 25 ... 30 times less than the cost of manufacturing new parts. When melting worn parts, up to 30% of metal is also irretrievably lost.
With long-term operation, cars reach such a state when the costs of funds and labor associated with maintaining them in working condition under ATP conditions become greater than the profit they bring in operation. This technical condition of the vehicles is considered to be critical, and they are sent for overhaul (CR). The task of the CD is to restore the performance and resource lost by the car to a new level or close to it with optimal costs.
1. General Provisions
1.1 Functional purpose, technical specifications and working conditions details
The valve is the main component of the engine gas distribution mechanism. The valves are used to periodically open and close the openings of the inlet and outlet channels, they are located in the cylinder head obliquely in one row. The inlet valve is made of chromium-nickel-molybdenum steel. The functioning of the repaired object - the camshaft cam runs onto the pusher, the pusher moves the rod 19, which in turn drives the rocker arm 20, which moves the valve 5 with the help of the striker. The valves operate in the zone of maximum temperatures ranging from -30 to +180 єС. The allowable seat chamfer angle should be within 44є45ґ-45є; changing this angle will lead to a decrease in pressure in the cylinder and unstable work engine.
1.2 Repaired product program
The annual production of parts is determined by the formula:
P = P sb · n · K p;
Where Psb is the annual output of the unit (assembly unit), pcs;
n is the number of parts of this name in the unit (assembly unit), pcs.;
K p - the coefficient of repair of a part, showing which part of the parts requires repair (K p = 0.8)
P = 4000 8 0.8 = 25600 pcs. (1.1)
Based on the annual program for the production of units, quarterly, monthly and daily tasks are determined. The type of production is set approximately based on the mass of parts and the production program of the unit (assembly unit) using table 1.1.
Table 1.1- Dependence of the type of production on the volume of production and the mass of the part
|
Part weight, |
Production type |
|||||
|
Single |
Small batch |
Medium batch |
High-volume |
Massive |
||
Because part weight is less than 1 kg, and the annual production of parts is 25600 pieces, then the type of production is medium-series.
The type of production determines the form of its organization, fundamental decisions in the design of technological processes, the means of technological equipment used, etc.
2. Analysis of part defects and requirements for the repaired part
The student receives information regarding defects in a part, first of all, from the technical conditions for repairs given in the fault detection cards. The cards contain: name and part number; her material; quality of the surface layer of working surfaces; list of possible defects; a sketch of a part with an indication of the location of defects; methods and means of detecting defects; the dimensions of the part according to the working drawing and the permissible dimensions (in terms of wear); Recommended remedies for defects.
A map of technical conditions for flaw detection should be provided in the PP. It is necessary to identify which defects of the part are removable during repair. Parts that have fatal defects cannot be repaired.
Using the working drawing of the part and the information obtained from the card of technical conditions for flaw detection, you should draw a repair drawing of the part, guided by GOST 2.604-2000 "ESKD. Repair drawings. General requirements".
The repair drawing shows only those views, cuts and sections that are necessary for the repair of a part (assembly unit). The surfaces to be restored are made with a solid thick line, the rest - with a solid thin line. Limit deviations of linear dimensions are indicated, as a rule, by numerical values, for example 018 + o, 1 or by statutory designations, followed by their numerical values in brackets.
For products that cannot be disconnected during repair (permanent joints made by riveting, welding, etc.), it is allowed not to execute drawings for individual parts. Instructions for the repair of such products are given on the repair assembly drawing, which includes the parts to be repaired, with the addition of images and data that explain the essence (content) of the repair.
On the repair drawing of the part being repaired by welding, brazing, metal coating, etc., it is recommended to highlight the corresponding area of the part to be repaired.
When repairing parts by surfacing, pouring (by welding, soldering, etc.), the name, brand, size of the material used in the repair, as well as the designation of the material standard, is indicated on the repair drawing. If, during the repair, the worn part is removed and replaced with a new (additional repair part), then the part to be removed is depicted by a dash-dotted line with two dots. The new part of the part (additional repair part) is performed on an independent repair drawing.
The categorical and fitting repair dimensions of the part, as well as the dimensions of the part repaired by removing the minimum allowance, are affixed letter designations, and their numerical values and other data are indicated on the shelves of lines - leaders or in a table.
To determine the method (type) of repair, the corresponding technological instructions are placed on the repair drawings.
2.1 Choice of ways to eliminate defects in a part
When choosing rational ways to eliminate defects in a part, we use annexes to guidelines for performing term paper... Reasonable restoration methods are established on the basis of the structural and technological characteristics of the part.
These include the type of the base material of the part, the type of the surface to be restored, the coating material, the maximum (minimum) permissible diameter of the restored surface (outer), the minimum permissible diameter of the restored surface (inner), the minimum thickness (depth) of the build-up (hardening), the maximum thickness (depth ) build-up (hardening), mating or landing of the restored surface, the type of load on the restored surface. Taking into account the nomenclature of representative parts recommended for restoration in one way or another, we select a number alternative ways restoration of the part being repaired.
The selected methods are evaluated by indicators of the physical and mechanical properties of parts: wear resistance coefficient, fatigue coefficient, adhesion coefficient, durability coefficient, microhardness. The final choice of restoration methods is made based on the technical and economic indicators of each method: specific material consumption, specific labor intensity of building-up, specific labor intensity of preparatory and final processing, specific total labor intensity, process efficiency factor, specific cost of restoration, indicator of technical and economic assessment, specific energy consumption.
1 Locksmith's - mechanical processing: processing to the repair size, setting an additional repair part, processing until wear marks are removed and giving the correct geometric shape.
2 Plastic deformation: drawing, drawing, straightening, mechanical expansion, hydrothermal expansion, electro-hydraulic expansion, rolling, mechanical reduction, thermoplastic reduction, upsetting, extrusion, rolling, electromechanical upsetting.
3 Application polymer materials: spraying (flame, fluidized bed), pressure testing, injection molding, spatula, roller, brush.
5 Manual welding and surfacing: gas, arc, argon-arc, forge, plasma, thermite, contact.
6 Electroplating and chemical coatings: direct current iron, periodic current iron, flow iron, local iron, chromium, flow chromium (jet), copper plating, incoating, alloys, composite coatings, electro-contact, electroplating, chemical nickel plating.
Choosing a way to restore the diametrical size of the valve stem.
We determine the design and technological characteristics of the valve: material - steel 40X10S2M; type of the restored surface - outer cylindrical, the minimum permissible diameter of the restored surface is 9 mm; minimum build-up thickness 1.02 mm; type of conjugation of the restored surface
Movable; the type of load on the restored surface is dynamic.
According to the design and technological indicators, the premium rate of restoration methods is determined (in accordance with the code designation of the application).
Considering that the valve is one of the main parts limiting the engine overhaul life, they determine the level of physical and mechanical properties that must be ensured when restoring the valve stem:
1 coefficient of wear resistance? 0.8;
2 endurance rate? 0.8;
3 adhesion coefficient? 0.8;
4 coefficient of durability? 0.8;
5 microhardness? 6000 MPa.
The above properties can be achieved in the following ways: (14, 14A, 15, 15A, 16).
For the convenience of comparing the technical and economic indicators of alternative recovery methods, the corresponding data are summarized in Table 1.2.
Table 2.1 - Technical - economic indicators alternative methods of valve stem restoration
Taking into account the disadvantages of methods of restoration, a rational method of restoration is iron (code 15).
2.2 Selection of technological bases
The choice of technological bases largely determines the accuracy of obtaining the linear and angular dimensions of the part during the repair process. When choosing technological bases, they are guided by the following provisions:
as technological bases for repairs, it is recommended to accept surfaces (axes) that served as technological bases in the manufacture of a part and do not perceive significant influences during operation;
all other things being equal, smaller errors occur when the same bases are used in all operations, i.e. when the principle of the unity of bases is respected;
it is desirable to combine technological bases with the design bases of the designed part, i.e. use the principle of overlapping bases;
surfaces used as technological bases in finishing operations should be distinguished by the highest accuracy;
In the absence of reliable technological bases for the part being repaired, artificial technological bases can be created by including in the technological process additional operations on which these bases are processed.
The choice of technological bases for the repair of a part is accompanied by the calculation of the positioning errors є (errors of misalignment of the bases), which is the basis for justifying the selected scheme for installing the part. The installation scheme is considered acceptable if the production error є у, equal to the sum of the basing error є and the error of the technological system є тс, does not exceed the tolerance T for the size maintained at the technological transition or operation being performed, i.e.
When performing the last technological transition of processing surfaces that are the boundaries of any size, the production error e y should not exceed the tolerance value T indicated on the repair drawing.
The valve axis is taken as the reference surface.
2.3 Route technological process of part repair
The technological process of repairing a part is developed on the basis of the need to eliminate all defects in the part, or their parts, if the part is complex, and the number of defects to be eliminated is large.
At the beginning of the technological process, we perform preparatory operations: cleaning, degreasing, straightening and restoration of base surfaces. Then we build up worn surfaces. In this case, first of all, they perform operations related to heating the part to a high temperature. If necessary, the parts are subjected to secondary dressing. After building up, we carry out the operations of mechanical processing of the part to be repaired.
We carry out control operations at the end of the technological process of repairing a part and after completing the most critical operations.
Choice technological equipment largely depends on the type of production. Since we have serial production, we use universal machines.
One of the criteria for choosing the route of the technological process is the analysis of the accuracy of the repair, in accordance with which a route is adopted for implementation that ensures the receipt of a part with the specified quality (accuracy) parameters.
Table 2.2 - Technological route of valve restoration
|
operations |
Operation name and content |
Equipment |
|
|
Flush and clean the valve from dirt |
Washing bath |
||
|
Defect Determine stem and valve chamfer wear |
Magnetoelectric flaw detector |
||
|
Surfacing To weld the working surface valve chamfers |
Installation for automatic surfacing |
||
|
Grinding Grind valve stem from taper |
Cylindrical Grinding Machine |
||
|
Grinding Grind the work surface valve chamfers |
Cylindrical Grinding Machine |
||
|
Electroplating Increase valve stem diameter by electroplating |
Galvanic bath |
||
|
Grinding Grind valve stem |
Round grinding shaft machine |
||
|
Polishing Polish the work surface valve chamfers |
Lathe |
||
|
Polishing Polish valve stem |
Lathe |
||
|
Flush and clean the valve from dirt |
Washing bath |
2.4 Technological operations for repairing a part
The structure of operations and the sequence of the transitions are closely related to the choice of technological equipment. The means of technological equipment include technological equipment, technological equipment, as well as means of mechanization and automation of production processes.
The choice of technological equipment depends on design features, dimensions and accuracy of repaired parts, technological capabilities equipment and the economic feasibility of its use.
When choosing fixtures, we are guided by the standards for fixtures and their parts, albums of typical fixture designs and reference books. When choosing the type and design of the cutting tool, we take into account the processing method, type of machine, dimensions, configuration, material of the workpiece, quality characteristics details. We pay special attention to the choice of material for the cutting part of the tool. In parallel with the choice of the cutting tool, we select the auxiliary tool. When choosing a cutting and auxiliary tool we give preference to standard tools.
We select methods and means of control during the repair process at the stage of analysis and development of technical requirements for the part being repaired.
For clarity, the selected equipment, tools, materials and equipment are presented in the form of a sheet.
Table 2.3 - Consolidated list of equipment
|
Name |
Name and model |
Power, |
||||
|
Operations |
Equipment |
|||||
|
Surfacing |
Surfacing installation |
|||||
|
Grinding |
Sianok grinder 3151 |
|||||
|
Grinding |
Grinding machine PT-823 |
|||||
|
Electroplating |
Iron bath |
|||||
|
Grinding |
Grinding machine 3151 |
Table 2.4 - Summary list of accessories and auxiliary tools
|
Name |
Name |
Designation, standard number |
|||
|
Operations |
Attachments and auxiliary tools |
||||
|
Surfacing |
Center stubborn |
7100-0009 GOST |
|||
|
Grinding |
7100-0009 GOST |
||||
|
Grinding |
Self-centering chuck |
7100-0009 GOST |
|||
|
Electroplating |
|||||
|
Grinding |
7100-0009 GOST |
Table 2.5 - Consolidated BOM
The allowance for surface treatment of repaired parts can be assigned according to reference tables or calculated by the calculation and analytical method. The calculated value is the minimum machining allowance sufficient to eliminate errors or defects of the surface layer obtained at the previous transition or operation at the transition being performed, and to compensate for errors arising at the transition being performed.
Currently, there is not enough statistical data required to calculate the allowances in the case of restoration of parts different methods, therefore, the corresponding allowances are assigned using tabular data.
2.5 Calculation of processing modes
The method of appointment and calculation of cutting conditions is used in individual, small-scale and serial production... Cutting data are selected in the following order.
Having studied the working drawing of the part and the specific workpiece to be processed, the length of the tool's working stroke is determined. The cutting tool and its durability are selected, taking into account the properties of the processed material, processing accuracy, rigidity of the AIDS system, the size of the allowance, etc.
Guided by the reference literature, find the depth of cut t mm. It is necessary to strive to ensure that the depth of cut is equal to the machining allowance, i.e .:
If for technological reasons (machining accuracy, surface roughness, etc.) such a ratio cannot be achieved, then in the first pass the depth of cut should be ti = (0.8 ... 0.9) z, in the second pass t2 = (0.2 ... 0.1) z.
Then select the feed s mm. To obtain maximum productivity, the aim is to use the highest machine feed, while taking into account the specified accuracy and surface roughness after processing, the rigidity of the AIDS system and the material of the cutting tool.
Knowing t and s for a specific operation, a specific tool, material of the workpiece and processing conditions, the cutting speed v is selected or calculated. If the tool is sharpened with diamond wheels, then the calculated cutting speed obtained must be multiplied by the correction factor. Having the cutting speed, the calculated spindle speed of the machine or the number of double strokes of the table and cutter is determined. Comparing the obtained value of na with the passport data of the machine, the actual spindle speed nph is set as close as possible to the calculated one. Having determined the cutting force Pp according to the reference data, the effective cutting power Na is calculated. N value eh should be less than or equal to the power of the machine's electric motor, i.e. N eh < Ndv. In this case, processing of the part is possible.
Let us determine Tsht.k for the operation of surfacing the end surface of the sub-gear of the pump of the D-37 engine.
Initial data: Valve material Steel 40X10S2M; working surface diameter 40 mm.
We produce surfacing with OZN-250U wire; wire diameter 2 mm.
Lot of parts - 8 pieces.
Square cross section
where r = 2 mm is the radius of the wire;
Length of the weld bead
where F is the cross-sectional area of the seam,;
L - seam length, mm;
г - density of the deposited metal,;
k is the coefficient of metal spatter (k = 0.9);
dн - coefficient of melting,;
I is the strength of the welding current, A;
kc - coefficient taking into account the complexity of the work;
Subsidiary
Additional time
TD = 0.05 (Tо + TV) = 0.05 (0.7 + 1.3) = 0.1 min, (2.4)
Piece-calculation time for surfacing one working surface of the valve chamfer
where Tпз - preparatory and final time, 10 minutes;
nn - the number of parts in the batch
Determine the norms of time for grinding work on the valve stem and the working surface of the valve chamfer
Main grinding time
where Sпр - longitudinal feed, mm / rev;
Li is the length of the processed surface, taking into account the penetration and the mileage of the grinding mileage, mm.
To1.2 = 4.9, min;
Tо3 = 6, min;
Additional time
TD1.2 = 0.27, min
TD3 = 0.4, min
The piece-calculation time for grinding the valve stem and the valve chamfer will be determined
1.2 = 7.15, min;
Let us determine the norms of time for the restoration of the valve stem by spraying.
Main time
where h is the thickness of the coating layer, mm;
g - density of the deposited metal, g / cm3;
h - current efficiency,%;
c - electrochemical cell, g / (A * h).
The auxiliary time for loading and unloading parts into the main tank and unloading from the main tank will be 0.18 minutes.
Operational closing time will be 6.39 minutes.
Piece-calculation time
where 1.12 - coefficient taking into account preparatory final time and extra time;
K - coefficient taking into account the use of equipment;
n is the number of parts simultaneously immersed in the bath, 8 pcs.
3. Technological documentation
Technological documentation includes flow charts, drawings of devices, special tools. The most important document is the technological map. There are three levels of detail in the description of technological processes: route, operational and route-operational. Accordingly, route and operational flow charts are used. In the route map, a description of all technological operations in the sequence of their execution is made.
The operational map for machining a part contains data about the workpiece being processed, the workpiece, the number and name of operations and transitions, the equipment used, fixtures, tools, cutting modes, machine and piece time, and the category of work. In the operational description of the technological process, a complete description of all technological operations in the sequence of their execution is made, indicating the transitions and technological modes, and a technological map and a route map are developed for each operation. With the route-operational description, the technological operations in the route map are indicated in abbreviated form in the sequence of their execution with full description separate, more important operations in operational charts.
Documents for the technological processes of repairing products are made taking into account the requirements of recommendations R 50-60-88 "ESTD. Rules for the preparation of documents for the technological processes of repair. "
Conclusion
In the course of the course work on the topic "Development of the technological process for restoring the valve of the D-37 engine", I analyzed the processes of restoring the part, the reasons for the failure of the part and ways to eliminate the failure. A flow chart was drawn up, which shows how to restore the part. When restoring the valve stem by spraying, I calculated the time norms, in terms of time it can be analyzed that it takes a lot of time to restore the valve stem, which can be reduced by changing the processing of the stem by grinding before spraying.
When performing this course work, we learned methods for assessing the quality of products, calculating and analyzing technological and dimensional chains, analyzing technological processes, choosing rational schemes for basing workpieces, calculating errors that determine the accuracy of machining, calculating allowances, optimal processing modes that ensure the specified quality parameters parts, as well as students must learn how to calculate the norms of time and cost of receiving parts.
We also got practical skills in the design of technological processes and machining to obtain the specified parameters of the part.
Literature
1.P.F.Dunaev, O.P. Lilikov: Design of units and machine parts. Moscow "High School". 1998 .-- 441s.
2. N.F. Baranov, E.A. Shishkanov: Methodical instructions for the course work on the discipline "Fundamentals of technology for the production and repair of cars." Kirov: Vyatka State Agricultural Academy, 2005 .-- 67p.
3. Matveev V.A., Pustovalov I.I. Time standards for disassembly, assembly and repair at repair enterprises.
4. Shadrichev V.A. Fundamentals of automotive technology and car repair, -L: Mechanical engineering, 1976. - 560s.
5. Volovik V.L. Handbook for the restoration of parts, - M: Kolos, 1981. - 381s.
6. Processing of metals by cutting: A handbook of a technologist / AAPanov, VV Anikin, NG Beim et al. Ed. A.A. Panova. M: Mechanical Engineering, 1988 .-- 736s.
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Description of the process of repairing the pivot rack of a freight car body truss. Repair specifications; surface preparation for welding and surfacing works. Control methods weld and labor protection. Drawing up a technological map for repairing a part.
term paper added 04/15/2013
Purpose and structural and technological analysis of the "shaft" part. Selection and justification of the dimensions of the workpiece; calculation of allowances and technological operations of processing a part. Selection of machine tools and cutting tools, ensuring the accuracy of processing; assembly process.
When developing technological processes for restoring parts, the main documents are: a repair drawing of a part, a route map (MC), an operational chart (OK), a flaw detection technological process map (KTPD) and a sketch map (FE).
A repair drawing is the main document according to which a technological process for restoring a part is being developed.
The initial data for the development of a repair drawing are:
working drawing of the part;
technical requirements for flaw detection of a part;
data on the choice of rational ways to eliminate defects;
technical requirements for the remanufactured part.
Repair drawings are performed in accordance with the rules provided for by GOST 2.604-2000 "Repair drawings" (Fig. 2.33):
places of the part to be repaired (restored) or processed are highlighted with a solid thick main line, and the rest - with a solid thin line;
dimensions and their maximum deviations, roughness values should be indicated only for the restored elements of the part;
on the repair drawings, only those views, sections, sections are shown that are necessary for the restoration of the part;
for a surface subjected to mechanical processing before building up (electroplating, surfacing, spraying, etc.), it is necessary to indicate the size to which the processing is performed. In this case, it is recommended to draw a sketch of the preparation of the corresponding section of the part on the drawing;
when developing a repair drawing for an assembly unit, parts that are restored and parts that cannot be replaced should be recorded in the specification;
when restoring the surface of a part using an additional part, the repair drawing is drawn up as an assembly drawing. An additional part is drawn on the same drawing or a drawing is being developed on it;
the categorical and fitting dimensions of the surfaces are affixed by letter designations, and their numerical values are given in the table. The table is placed in the upper right part of the drawing;
The categorical dimensions are the final repair dimensions of the part, established by the technical requirements for a certain category of repair (in the technical literature, they are often called repair). Fitting are the repair dimensions of a part set to fit the part "in place";
8) in the field of the repair drawing, in addition to the table of repair dimensions, a table is placed in which the numbers, names of defects, recurrence coefficients of defects, the main and acceptable methods for their elimination are given. The previously substantiated rational (optimal) recovery method is taken as the main one. When restoring parts by welding, surfacing, spraying, etc., the name and designation (brand) of the material and protective environment should be indicated in the table. Below the table of defects, conditions and defects are indicated under which the part is not accepted for restoration. In this case, the sizes of the graphs and rows of the table of defects are determined by the volume of the text part and the availability of free space in the drawing;
in the field of the drawing above the main inscription, set out the technical requirements related to the restored surfaces: heat treatment and hardness; limit deviations of sizes, shapes and relative position of surfaces, etc.; requirements for the quality of surfaces (the presence of pores, cavities, delamination, etc.) and others;
if necessary, in the free field of the drawing, instructions on the basing and the technological route of restoration are given according to the main method of eliminating the defect;
repair drawings are recommended to be made in A1 format. In this case, the image of the part, specification, technical requirements and a table of categorical sizes is performed on the first sheet, and the types, cuts, sections and a table of defects can be performed on subsequent sheets;
12) when designating a repair drawing, the letter "P" (repair) is added to the designation of the working drawing of the part. If additional parts are used, add the letters "SB" (assembly drawing).
The technological process of restoring parts can be represented in the form of a route, route-operational and operational description. At the same time, the completeness of documents for single and standard (group) technological processes of restoring parts can be different and is drawn up in accordance with GOST 3.1121-84 "General requirements for the completeness and execution of sets of documents for standard and group technological processes (operations)" or according to RTM 10.0024 -94 "Procedure for the development and execution of technological documentation for the repair and restoration of worn-out machine parts." Figures 2.34 and 2.35 show examples of the design of the title (Form 12) and subsequent (Form 12a) sheets of the technological process of restoring a part in accordance with RTM 10.0024.
The route map is an integral and integral part of the kit, drawn up in accordance with GOST 3.1118 (Forms 2 and 1b). With the routing and routing-operational description of the technological process, this document describes the entire process in the technological sequence of operations with the indication of equipment. In the operational description of the technological process, MC plays the role of a free document, which indicates address information (workshop number, site, workplace, operation), the name of the operation, the list of documents used in the operation, technological equipment and labor costs. Technological modes should be set in accordance with the sections of the MK. Examples of MK design (title and subsequent sheets) are presented in Figures 2.36 and 2.37.
OK - obligatory document the technological process of restoring parts, which includes a sequential description of the technological process for all operations, indicating equipment, fixtures, tools, processing modes, techniques and methods of execution, consumables and labor standards. Operational maps are made in accordance with GOST 3.1404-83 (Form 3) and must contain sketch maps drawn up in accordance with GOST 3.1105-84 (Form 7 and 7a).
When registering OK, the following basic requirements should be met. The name of the operations is recorded briefly in the nominative case, for example: "Surfacing", "Turning", etc. Operations are assigned numbers that are multiples of five, for example: 05, 10, 15, 20, etc. The content of operations (transitions) is written down briefly and clearly, with a verb in an imperative mood, for example: "Fuse the surface (1) to 0 56". Figure 2.38 shows an example of the execution of an operational recovery card.
KTPD is an obligatory element of the technological process of defective detection of parts, which includes the name of defects and methods of their elimination, methods and means of control, admissible without repair, limiting dimensions.
Rice. 2.34. An example of the design of the cover sheet of the technological map of the restoration of a part in accordance with RTM 10.0024 (Form 12)
Rice. 2.36. An example of the design of the header (first) sheet of the route map in accordance with GOST 3.1118 (Form 2)
Rice. 2.37. An example of the design of subsequent sheets of a route map in accordance with GOST 3.1118 (Form 1b)
Rice. 2.38. An example of drawing up an operating card in accordance with
with GOST 3.1404 (Form 3)
The flaw detection technological process map is developed in accordance with the standard R50-60-88 "Rules for drawing up a document for the repair technological process". Graduates respectively fill in the columns "Workshop number", "Number of workers", "Tariff scale code", "Norm type code", "Т ПЗ, Т pcs", "Profession code". In the column "Operation number" indicate the number of the defect, and in the column "Name, content of the operation" it is allowed to indicate the name of the defect. In the column "Special instructions" they give a conclusion: reject, restore. In this case, it is allowed to indicate the methods of restoration (ironing, surfacing, spraying, etc.). Figures 2.39 and 2.40 show the forms, main inscriptions for the first (Form 5) and subsequent (Form 5a) sheets of KTPD in accordance with GOST 3.1115-79. An example of KTPD registration is shown in Figure 2.41.
A sketch map is a graphic document of a part remanufacturing workflow that is developed for operations and transitions. The sketch map is drawn up in accordance with GOST 3.1105-84, GOST 3.1129-93 and GOST 3.1130-93. FE contain diagrams, tables, defects, technical requirements necessary to perform an operation or transition, as well as explanatory methods and means to ensure the safe performance of technological operations. The need to develop separate FE in route-operational and operational processes is determined by the developer. FE is developed on the basis of the drawing and overhaul manuals. The sketch for the restoration process must indicate the numbers and names of defects, technical requirements, size numbers of the surfaces to be treated. On a properly designed sketch, the number of images should be minimal and at the same time the sketch should be readable without difficulty. Elements of parts, dimensions that are not related to the surface being machined in this operation or in this process, are not indicated in the sketch.
When issuing a FE, the following requirements should be met:
the required number of images (views, cuts and sections) on the sketch of the workpiece must be sufficient for a visual and clear presentation of the processed surfaces and the possibility of setting dimensions, technological bases and clamping forces. When performing FE flaw detection, the required number of images on the sketch is set from the condition of ensuring the visibility and clarity of the location of the controlled surfaces of the part, which will allow high-quality flaw detection;
the processed, controlled and defective surfaces are encircled by the main line, 2 ... 3 times thicker than the solid line and numbered on the sketch with Arabic numerals. In this case, the surface number is affixed in a circle (circle) with a diameter of 6 ... 8 mm, connected with an extension line with the image of this surface and numbered in the direction of clockwise movement;
on the operational sketch, the workpiece is shown in the state that it acquires as a result of this operation. On the FE for a given technological operation, according to ESKD, the dimensions, maximum deviations, the nature of the connection, the roughness of the treated surface, base, technical conditions etc.;
the sketches in the same scale as the workpiece should be simplified depicting cutting tools in the final position for processing, and tools for processing holes (drills, countersinks, taps, etc.) in the initial position. For multi-tool processing, the operating sketch must show all cutting tools;
to designate technological bases, supports and clamping devices, use the conventional signs in accordance with GOST 3.1107-81 "Supports, clamps, installation devices. Graphic symbols ".
An example of a sketch map is shown in Figure 2.42.
The FE is indicated by technological bases, supports and their corresponding clamps. Right choice technological and measuring bases - one of the conditions for high-quality manufacturing of a part. The main provisions of the theory of basing and terminology are given in GOST 21495. Below are the provisions that a qualified worker should know.
When choosing the bases, it is taken into account that the imposition of geometric and kinematic connections on the body (in the x, y, z coordinate system) allows it to deprive it of six degrees of freedom (three movements along the axis and three rotations around these axes) and to ensure reliable fastening during processing. Six links, which prevent the workpiece from moving in six directions, can be created by contact with the parts of the fixtures.
Installation diagrams are used to indicate the bases that determine the required position of the workpiece and the fastening forces that ensure the constancy of this position. The choice of bases is determined by the design and requirements for dimensional accuracy and the relative position of the surfaces of the parts.
When developing cutting processes and choosing bases, it is customary to combine technological bases with measuring ones or take surfaces as technological bases, the position of which in relation to the measuring bases is determined by a dimensional chain with a minimum number of constituent links. When choosing bases, preference is given to the location option, where the tolerances of the constituent links of the dimensional chain are economically profitable. At the same time, they analyze and provide for the possibility without changing the bases, given that changing the base during processing introduces errors associated with inaccuracies in the relative position of the bases.
The expediency of changing the bases is justified by calculating the dimensional chains taking into account the errors associated with the processing features (the appearance of installation errors, distortion of the shape and size of the workpiece during heat treatment, etc.). If the configuration of the workpiece does not allow the selection of technological bases and stable orientation of the workpiece, then artificial bases-tides (bosses), additionally machined tapered holes (center slots), tapered outer and other surfaces are created. If, when installing workpieces of low rigidity, the number of support points does not provide sufficient rigidity of the workpiece, it is recommended to use additional movable supports (movable steady rest, etc.).
Rice. 2.39. Form and main inscriptions for the title (first) sheet of KTPD in accordance with GOST 3.1115 (Form 5)
Rice. 2.40. Form and main inscriptions for subsequent sheets of KTPD in accordance with GOST 3.1115 (Form 5a)
Rice. 2.41. An example of registration of KTPD
When choosing bases for processing a workpiece in the first operation, where the installation is carried out on untreated surfaces, surfaces are selected as preliminary bases with respect to which the remaining surfaces can be processed (with complete processing from one installation), or surfaces used in subsequent operations as technological bases ... Placing the workpiece on the bases should ensure an even distribution of allowances for the subsequent processing of the most critical surfaces.
The surfaces taken as rough bases must be of sufficient size, configuration and roughness to ensure the required accuracy and rigidity of fixing the workpiece in the fixture.
When performing subsequent operations, it is advisable to install blanks on the bases processed in the first operation. Re-installation of the workpiece on the rough bases can be used when installing with the alignment of the workpiece on previously processed surfaces (check bases). When choosing bases for cutting operations, surfaces are taken as finishing bases that provide the necessary installation accuracy and secure fixing in the absence of deformations affecting the processing accuracy.
To ensure the constancy of the position of the workpiece achieved during basing, it is necessary:
in accordance with the adopted basing scheme, provide a fastener that creates continuity of contact between the workpiece and the device supports during the operation;
to reduce contact deformations by establishing and maintaining during processing the necessary requirements for the accuracy of the geometric shape and surface roughness of the bases of the workpiece and fixture;
select the points of application of forces in such a way that the line of their action passes through the support points;
establish the sequence of application of the clamping forces so as not to cause a change in the position of the workpiece during clamping.
There are fixed and movable supports. The fixed support of the device (locating pin, base plate, etc.), as well as the support, forcibly moved when fastening and centering the workpiece (chuck jaws, rear center of the glass, etc.), deprives the workpiece of one, two, three and four degrees of freedom. Movable support - supplied or self-installed support of the device, designed to increase the rigidity of the installation (steady, etc.), but not depriving it of the degrees of freedom. A prismatic fixed support deprives the workpiece of two (for a short prism) or four (for a long or composite prism) degrees of freedom. The prismatic movable support deprives the workpiece of one degree of freedom, excluding its movement along the axis perpendicular to the plane of symmetry of the prism.
Tables 2.7 and 2.8 show the designations of supports and clamps when depicting installation diagrams on FE (GOST 3.1107), and in Table 2.9 - examples of applying supports, clamps and installed devices on the diagrams. Wherein
clamps have the following designations: pneumatic - P, hydraulic
Table 2.9 - Examples of application of designations of supports, clamps and installation devices in diagrams
The number of points of attachment of the clamp to the part is recorded to the right of the clamp designation. On diagrams that have several projections, it is allowed not to indicate the designations of supports and clamps relative to the part on separate projections, if their position is uniquely determined on one projection.
Several designations of the supports of the same name on each view can be replaced with one.
A combination of the force and the support image is used to ensure the fastening force applied at the place of support. The designations of the reference points are applied in the front view - on the contour line depicting the surface of the workpiece taken as the base; in the top view - inside the contour of the workpiece. When installing the workpiece on the machine, with alignment according to the marking on the installation diagram, they show the position of the marking line in combination with the image of the control points. It is necessary to strive to ensure that the design, technological and measuring bases coincide, as this significantly increases the processing accuracy.
2.4 Space-planning and structural solutions of buildings and structures of technical service enterprises
General requirements for the planning of technical service enterprises
The layout of a technical service enterprise should be understood as the layout and relative location of production, warehouse and administrative premises in the building plan or detached buildings intended for repair, maintenance and storage of machines on the territory of the enterprise.
The development of a planning solution for a technical service enterprise is a rather difficult task. This complexity is due to the need for mutual coordination of the elements of production, warehouse and other units, the sizes of which are determined as a result of technological calculation with the adopted technological process and organization of production, taking into account the requirements for the organization of traffic, climatic conditions, construction, fire safety, sanitary and hygienic requirements, requirements for environmental protection, etc.
The basis for the development of planning solutions for a technical service enterprise is the following technological requirements: the relative location of zones and sections must correspond to the technological process; the structural scheme of the building and the location of production units in it should ensure the possibility of changing technological processes in the future and expanding production without significant restructuring of the building.
When arranging production and storage facilities in the production building, its location on the master plan is taken into account to determine the direction of entrances to the building and exits from it in accordance with the organization of the movement of cars on the territory of the enterprise, as well as the direction of the prevailing winds (according to the annual wind rose) for correct placement on master plan of fire and explosion hazardous and hazardous to human health industries.
2.4.2 General plan of the technical service enterprise
The master plan is a plan of a land plot allotted for building, oriented relative to the cardinal points, with an image on it of buildings, structures, storage areas, traffic roads along the territory of the site in accordance with the district planning scheme with green spaces and fences applied on it.
Master plans are developed in accordance with the requirements of SNiP P-89-80.
The general plan of the enterprise, as a rule, is carried out on a scale of 1: 500 or 1: 1000.
The development of a master plan usually begins with the identification of a complete list of objects intended for placement on the designated site. Then the area is determined and dimensions each of these objects. Initially, the location of objects on the site plan is outlined, taking into account the flow diagram in the production buildings and the movement of freight traffic of the entire production process. In order to achieve the greatest technical and economic efficiency in the development of a master plan, several variants of freight traffic schemes are drawn up, as a result of comparison of which the most rational is chosen.
The main provisions that guide the development of the general plan of the enterprise are as follows.
F 3 PS - the area of construction of industrial and warehouse buildings, m 2;
F 3 BC - construction area of auxiliary buildings, m 2;
F on - area of open areas for storage of rolling stock, m 2;
K 3 - the density of the building area,%.
The building area is defined as the total area of buildings and structures in the plan, open areas for storing cars, warehouses, sheds, reserve areas.
The building area does not include the area of highways, sidewalks, blind areas, green spaces, recreation and sports grounds, as well as open parking lots for individual owners. The building density of the territory of the enterprise is determined by the ratio of the building area to the area of the site (K 3 = 0.30 ... 0.35).
The coefficient of use of the territory is defined as the ratio of the area occupied by buildings, structures, roads, sidewalks, blind areas, recreation areas, open areas for storing cars, landscaping, to the area of the enterprise site (K u = 0.45 ... 0.50).
The greening coefficient is the ratio of the area of green spaces to the area of the enterprise site (K 0> = 0.15).
The values of the coefficients characterizing the quality of the master plan for enterprises and units of the technical service of the agro-industrial complex located in cities and in multi-storey buildings are much higher.
On the drawing of the master plan, place:
master plan diagram;
explication of buildings and structures in the sequence corresponding to their serial numbers in the drawing (Table 2.10);
technical and economic indicators of the general plan (Table 2.11);
the direction of the prevailing winds (wind rose).
On the drawing of the general plan, images of buildings, structures, parking lots, gate fences, areas with a hard surface are applied in accordance with the adopted conventions according to GOST 21.108-78 (Table 2.12).
Table 2.10 - Legend of buildings and structures
Table 2.12 - Conditional graphic images and designations in the drawings of general plans
In order to orient the land plot in relation to the direction and duration of the winds for a given period of time, on the master plans in the upper left corner outside the drawing field, an image of a wind rose is applied, which determines the countries of the world and the direction of action of the prevailing (dominant) winds to ensure the most favorable conditions of natural lighting and ventilation of premises, location of industrial buildings and structures. In addition, an explication of buildings and structures and technical and economic indicators are placed below or on the right outside the drawing field.
The wind rose is a graph characterizing the wind regime in a given area based on long-term observations (Figure 2.43). It is being built for a month, a season, a year. The length of the rays of the wind rose, diverging from the center in 8 or 16 directions, is proportional to the frequency of the winds in these directions (as a percentage in each direction of the total number of observations). The ends of the rays are connected by a broken line.
Rice. 2.43. Wind rose
As an example, figure 2.44 shows general plan technical service enterprises for 130 tractors and 25 cars. With the aim of further expansion and reconstruction, it is necessary to provide for reserve sites both on the territory of the enterprise itself and outside it.Repair of the main parts of the repaired unit is carried out using route technology.
The main parts of the repaired unit include shafts, axles and gear wheels and gears. Shafts have smooth cylindrical surfaces, journals, splines, collars, marks and threaded holes. During operation, wear of the bearing and landing journals and collars, wear of the splines may appear on these surfaces.
Repair of bearing seats. Not significant damage to rubbing surfaces in the form of wear. Eliminate by finishing with special pastes or grinding, with large wear, as well as with the appearance of taper and ovality, the restoration of seats is carried out by processing to a repair size and surfacing, metallization or electroplating, with wear of more than two mm. the shafts are restored by surfacing, by increasing the necks with chromium plating. After building up the metal, the seats are ground.
Repair of cogwheels and gears. They are made of alloy steels; during operation, the gear wheels and gears have the following defects: wear and tear of teeth, wear of the keyway in width is eliminated by automatic arc welding and surfacing or manual arc welding and surfacing. This method is simple, economical and labor-intensive. When the teeth are worn out, they are restored by industrial surfacing with an oxygen acetylene flame or electric arc surfacing. Electric arc surfacing is performed with electrodes with high-quality coatings; in gas surfacing, rods of the same chemical composition as the metal of the cogwheel are used. Worn gears of small modules up to 5-6 mm are restored by continuous surfacing followed by milling or planing. depends on the strength of the gear rim and the material
Route map
The route kata is in the appendix
Development of a technological process for the repair of a driven shaft using route technology
005 locksmith
010 screw-cutting lathe
015 locksmith
020 surfacing
025 thermal
030 screw-cutting lathe
035 milling
040 thermal
045 grinding
050 final control
Technological map for the repair of a part
The technological map for the repair of the part is in Appendix B.
Surfacing operational map
The operational map of surfacing is in Appendix B.