Shaft Recovery

Contents

Contents

Introduction

1. DESIGN AND OPERATING CONDITIONS ANALYSIS

2. DEVELOPMENT OF PART CLEANING TECHNOLOGY

2.1.Basification of cleaning quality requirements and methods of its control

2.2. Characterization of contaminants and selection of cleaning methods

2.3. Selection of cleaning media equipment and cleaning modes

3. DEVELOPMENT OF PART DEFECT TECHNOLOGY

3.1. Characteristics of defects,

3.2. Selection of methods and means of control

3.3.Technological route of defect

4. PART RECOVERY PROCESS DESIGN

4.1. Substantiation of methods of correcting defects and restoring the part

4.2. Selection of process bases and baselines

4.3. Part Recovery Process Route

4.4. Development and rationing of technological operations

5. CONCLUSION

Literature

APPENDIX 1. Set of documents for shaft recovery process

Introduction

The topic of the course project "Develop the technological process of shaft restoration" is relevant, since at present repair and maintenance enterprises are mastering the technology of repair work related to the restoration of agricultural machines. Depending on the specific requirements for part repair, part material, and working conditions, different recovery methods are used. The use of a method is also related to the technical equipment of the repair plant and the scope of work for which it is designed. To improve the reliability and durability of machines, it is necessary to put into practice the use of new wear-resistant materials, constantly mechanize and automate processes. The economic feasibility of restoring parts is primarily due to the possibility of repeated (very often repeated) use of 6575% of parts. The cost of restoring parts does not exceed 75% of the cost of new ones, and the material consumption is 1520 times lower than in the manufacture of parts.

The development of recovery technology uses typical design solutions given in the literature. At the same time, the recommendations given in [1], [2] are accepted as the methodological basis for the development. This is primarily related to design materials: a repair drawing, a diagram of the part restoration process, and the development of small mechanization tools.

Data [ 3], [4] were widely used in the project. The materials developed in the course design can be used in practical work in solving the following problems: the development of repair drawings, the design of the process diagrams for disassembly (assembly) of assembly units, the design of means for small mechanization of repair work.

Part Design and Working Conditions Analysis

Shaft wear is determined by cyclic loads, lubrication mode and degree of its stability, speed of friction surfaces movement, degree of environmental aggressiveness, quality of treatment and state of friction surfaces, etc.

The shaft has a number of cylindrical surfaces, which are mounting surfaces for rolling bearings, a threaded surface, as well as splines that work for cutting and crushing. Conical surfaces and fillets are also present. The variability, as well as the large amount of transmitted loads, affects the durability of the working surfaces and contributes to a faster appearance of defects.

During operation of the shaft, a number of defects arise:

1. Wear of bearing surface to size less than Ø39.99 mm;

2. Wear of bearing surface to size less than Ø44.99 mm;

3. Damage of thread M 33х1.5 - 8g;

4. Damage of thread M 30х1.5 - 8g;

In our case, two defects are considered: wear of the mounting surface for the bearing to the size less than Ø39.99 (def.1), damage to thread M 33 x 1.5 - 8g (def. 3).

There are selection signs in which the part is not recoverable and is scrapped - these are cracks and fractures. Physically, these defects can be eliminated, but the durability of such a part will be very small, since the shaft is subjected to constant power loads and restored from cracks and fractures, will very quickly fail again. Such a restoration is economically unjustified, and a part with cracks and fractures should be replaced with a new one.

The shaft has length L = 361.5 + 1.35 mm. material of part Steel 40X GOST 454371 .

Development of Part Defect Technology

3.1 Characteristics of defects

In this course design, it is necessary to design the process of restoring the part - shaft.

In our case, two defects are considered: wear of the seat under the bearing to a size less than (def.1) and damage to the thread

M 30х1.5 - 8g (def.3).

There are selection features in which the part is not recoverable and is recycled - these are cracks passing along the surface of the hole and fractures. Physically, these defects can be eliminated, but the durability of such a part will be very small, since the shaft is subjected to constant power loads, and the shaft restored from cracks and fractures will very quickly fail again. Such a recovery is economically unjustified, and a part with cracks and fractures should be replaced with a new one

3.2 Selection of methods and means of their control

When accepting a part for repair, we first perform an external inspection with the naked eye or using a magnifying glass, check for touch, and puncture. Thus, we identify cracks, nicks, risks, debris, holes, dents, cramps.

Then, using a universal and special micrometer tool smooth MK501 GOST 650790, we determine the geometric parameters of the part, detect defects in shape, gaps and interference.

Devices and devices specially designed for this purpose, such as the PARKER DA1500 magnetic flaw detector, are used to detect hidden defects, check hardness, and check the mutual position of parts elements;

3.3 Part Defect Process Route

During puncturing, refer to the working drawing of the part and technical documentation for this part.

When designing the part defect process, we draw up a sketch map of the part and a map of the defect process. Controls (equipment and tools) for each defect are tabulated.

Part Recovery Process Design

4.1 Substantiation of methods for elimination of defects and part repair

As a typical version, he used "Repair drawings and maps of technological processes for the restoration of parts of cars, tractors, agricultural and livestock machines." The following defects have been proposed:

Wear of shaft surface for bearings - build up in CO2 medium.

Thread damage - build up in a CO2 environment.

Bearing Shaft Surface Wear-Edit the ribbon in a contact manner.

Wear of the shaft surface for bearings - vibration surfacing.

To eliminate each defect, a rational method, i.e. technically sound and economically feasible, must be chosen.

The rational method of restoring parts is determined using criteria: technological (applicability), technical (durability) and technical and economic (generalizing).

The technological criterion characterizes the fundamental possibility of using several methods of restoration, based on the structural and technical characteristics of the part or certain groups of parts. These include geometrical shape and dimensions, material, thermal or other type of surface treatment, hardness, surface roughness and accuracy of part manufacture, nature of load, type of friction and wear, wear dimensions.

According to the technological criterion for defect No. 1 and 3, as the main method of restoration, we take the method of surfacing in a CO2 medium. Alternative recovery methods with which we will compare efficiency are vibration surfacing and contact welding of the tape.

The main advantages of surfacing in the CO2 environment compared to various types of surfacing are that in this method there is no harmful release and formation of slag crust, surfacing is easily mechanized and automated (which allows increasing labor productivity by 2... 3 times, reducing the consumption of the metal to be built up by almost 4 times, improving working conditions).

The technical criterion (durability) evaluates each method (selected according to the technological characteristic) of elimination of defects of the part in terms of restoration of surface properties, i.e. ensuring operability due to sufficient hardness, wear resistance and adhesion of the coating of the restored part.

For each of the selected several recovery methods, we determine a comprehensive qualitative evaluation by the value of the durability factor

4.2 Selection of process bases and basing facilities

The bases are the surfaces, lines, points, or aggregates needed to orient the part on the machine, position it in a subassembly or product, and measure it. By purpose, they are design, technological and measuring.

Design bases - a collection of surfaces (lines, points) from which the dimensions and positions of parts and assemblies are specified during the development of the machine design.

Process bases - surfaces (lines and points) used to install the part on the machine and orient it relative to the cutting tool.

Measuring bases - surfaces (lines or points) from which the dimensions to be measured are measured.

Process bases are divided into main and auxiliary bases:

The main technological base is the surface (line, point) that is used to orient the part on the machine, in a unit or machine.

Auxiliary process bases - surfaces (lines, points) that are necessary when installing a part on a machine, but they do not affect its operation in the machine.

When selecting technological bases, the following provisions should be followed:

1. Use auxiliary bases. Auxiliary bases are used as technological bases, since the main ones, being joint surfaces, wear out during operation and cannot serve as technological bases.

2. Use basic databases. Some parts do not have auxiliary bases, but the main ones are worn out. The least worn base base is selected as the process base, treated and used as the main base.

technological base, other surfaces are treated.

3. Uses the bases of the part to connect. In some cases, the workpiece can be more accurately mounted to the machine along with the workpiece to be connected.

4. Create new databases. If it is not possible to use the bases used in the manufacture of parts, it is necessary to select treated surfaces that are connected to the surface with a straight, possibly more accurate size. It is necessary to combine the installation and measurement bases. Otherwise, the accuracy of the part deteriorates (the so-called basing error occurs).

5. Processing with minimum number of bases. It is best to carry out treatment (preparatory, coating and final mechanical) on permanent bases. If they change, processing accuracy is reduced.

In accordance with the above provisions, to restore our details, we choose the following bases:

- shaft rotation surfaces;

- conical surfaces of shaft alignment holes.

4.4. Development of technological operations

Starting the development of the roadmap, the process of the recovery process is scheduled for all defects. At the same time, they strictly adhere to the following main provisions:

performing base surface recovery operations; surfaces of parts that are not worn or have the least wear are taken as installation bases; when restoring parts, they strive to use the bases used in their manufacture; maintain the unity of technological and design bases;

provide for operations in which the largest layer of metal is removed - rough processing (these include the groove of the surface before welding, removal of worn threads, etc.);

in one operation, restoration of several worn-out surfaces is combined if they are restored by one technological method (welding, surfacing, electroplating, locksmithing, etc.);

If the part is repaired using mechanical and heat-related machining (welding, surfacing, quenching), they are performed in the following order: a rough mechanical operation associated with significant heating of the part, and straightening, then a finishing mechanical operation (for example, grinding);

do not combine finishing and draft operations, as they

at the end of the process, finishing operations (finishing groove, grinding, polishing operations, etc.) are provided;

control operations are typically recorded at the end of the process.

We will select and calculate the process modes for the slip-grinding operation.

Conclusion

As a result of this course project, an analysis of the design, working conditions and defects of the part was carried out. Possible contaminants, cleaning criteria and requirements for cleaning the part to be repaired are considered. Method of cleaning and means of cleaning are considered. You have selected the necessary equipment and part cleaning modes.

The defective process is designed. The necessary measuring tool is selected. Defects have been identified and need to be corrected.

Analysis of possible solutions has been carried out and the most applicable one has been chosen. Among a variety of methods for elimination of defects specified in the task, a method for recovery of surfacing in a CO2 medium is chosen (using wire 1.2 Np30XGSA GOST 454371). This process is most suitable, cost effective and promising. You have selected the required bases and baselines. The process recovery route was designed, the modes and time standards were calculated

Thread M33x1.58g, mounting surface for bearing Ø40 mm have been restored.

Literature

1. Machinery Repair Technology/E.A. Puchin [et al.]; under the general. Ed. E.A. Puchina.-M: KolosS, 2007.- 488s.: il.

2. N.V. Molodykh, A.S. Zenkin. Restoration of machine parts/Young N.V., Zenkin A.S. - M.: Engineering, 1989-479.

3. Repair of machines. Course and degree design/V.P. Miklush [et al.]; under the general. Ed. V.P. Miklusha. - Mn.: BGATU, 2004.- 490s.

4. Cutting materials processing (Technologist's Handbook )/A.A. Panov [et al.]; under the general. Ed. A.A. Panova. -M.: Mechanical engineering . - 1988.736c: yl

5. Time standards for dismantling, assembly and repair works/GOSNITI; redcol.: V.I Trofimenko [and others]. – M.: Page STATE THREADS.263.

6. Metal cutting/G.A. Monakhov [et al.]; under the general. Ed. G.A. Monakhov. - M.: Engineering. - 1988.430s.: il.

7. V.A. Matveev, I.I. Pustovalov "Technical rationing of repair work in agriculture," - M.: Kolos, 1979-288.

8. Handbook of engineering technologist in 2 volumes/A.M. Dalsky [et al.]; under Society. Ed. A.M. Dalskogo.-M: Mechanical Engineering, 2001, 944s., il.