Accessory for cylinder block stretching

Contents

Contents

Introduction

Repair Object Analysis

Select a method to repair defects

Conclusion

List of used literature

Applications

Introduction

Car repair is an objective necessity, which is due to technical and economic reasons.

Firstly, the needs of the national economy in cars are partially met through the operation of repaired cars. Secondly, the repair ensures the continued use of those elements of cars that are not completely worn out. Thirdly, repairs contribute to saving materials for the manufacture of new cars. When restoring parts, metal consumption of 20... 30 times lower than in their manufacture.

The increase in the production of cars and their inflow from the foreign market leads to an increase in the absolute volume of repair work.

The general principles of the design of the process of restoring parts involve the selection of more rational technological methods for eliminating defects and the construction of a general optimal sequence of technological operations: elimination of general deformation of the part, restoration of technological bases, preparatory operations before the application of metal coatings and polymeric materials, coating, rough treatment of the restored surfaces, finishing operations, quality control, part washing. When restoring the engine of the car and its main parts, the required dimensions, shape, mutual arrangement of surfaces and axes, surface roughness and other parameters of working conjugations of the parts must be provided.

Select a method to repair a defect

Cylinders can be worn out unevenly, and the unit during long-term operation, albeit slightly, is deformed. Moreover, when manufacturing the block, the necessary technological requirements are not always met, which, for example, leads to non-parallelism of the cylinder axes.

As a result, the bores can straighten out the geometry of the "curve" block itself, in other words, make the cylinder axes mutually parallel and simultaneously perpendicular to a certain base surface.

With the provision of parallelism - usually there are no problems. No matter how you put the unit on the machine, no matter how you stretch it, parallelism will be ensured if, of course, the unit is not reinstalled on the boring machine table during repair.

Methods for restoring cylinder liners

To restore the outer surface of the cylinder liners, it is necessary to clean the outer surface of the liner from scale and corrosion.

A steel brush and lathe will be required to clean the surface of the sleeve.

For cleaning cylinder liners there is a special installation OM21601.

Cleaning material for OM21601 unit: metal sand, bone crumb, flux.

Capacity of OM21601: 40 cylinder liners per hour.

Operating pressure of compressed air of sleeve cleaning plant: 0.5 0.56 MPa.

Elimination of cavitation damage of cylinder liners with epoxy composition.

Cavitation failures of cylinder liners are eliminated by coatings based on epoxy resins and are eliminated in the following sequence:

Grinding of cylinder liner surface (to metallic gloss);

Degreasing of cylinder liner surface (technical acetone);

Preparation of epoxy composition (after adding hardener, the composition should be used in 20 minutes);

Application of epoxy composition to the surface;

Hardening of the applied layer (at a temperature of 20 degrees Celsius 3 days).

Before applying the epoxy composition to the cylinder liner, it is necessary to apply the liner to a temperature above 40 degrees Celsius. Epoxy composition shall be applied to the cylinder liner surface with a special spatula.

The epoxy composition must be free of water, oil and dirt. Leaks of epoxy composition on the mounting belts of the cylinder liner during cylinder liners repair are not allowed.

Method of elimination of cavitation breakages of cylinder liners by welding of steel tape .

There is a simple method of contact welding of steel tape to eliminate cavitation damage of the cylinder liner.

Unit 011107 is used to weld the steel strip to the surface of the sleeve. Steel tape is cut from steel sheet 0.3 mm thick.

The damaged portion of the liner shall be covered by 510 mm steel tape.

The steel strip is welded by a single weld point to the surface of the sleeve so that the weld point is not further than 12 mm from the edge of the strip. Lower part of steel belt is welded symmetrically to upper one welding point. The tape edges are then welded.

For welding, it is recommended to use wide electrodes in order not to destroy the sleeve.

The diameter of the electrodes is 150 mm, the width of the upper working part is 5 mm, the lower - 12 mm.

When the steel strip is already welded, the sleeve bands begin to be ground to a nominal size. Grinding machine is used for grinding bands of cylinder liner. Carefully install the cylinder liner on the grinding machine so that no deformation of the liner occurs. Notice that the welded layer does not protrude beyond the surface of the landing shoulder.

We take it upon ourselves to restore the inner surface of the cylinder liners .

After cleaning, control and elimination of cavitation damage on the outer surface of the cylinder liner, restoration of the landing belts, it is necessary to treat the inner surface of the cylinder liner for a repair size, that is, increase the inner diameter of the cylinder liner by 0.50.7 mm. depending on the type of engine.

Dilution of engine cylinder liners.

Dilution of cylinder liners is carried out on a diamond boring machine .

The cylinder liner stretching machine 278, 278H is equipped with a special liner attachment device.

Dilution of cylinder liners is carried out, usually in one pass.

Tightening mode of cylinder liner on diamond boring machine:

Spindle speed 112 rpm.

Tool feed 0.2 mm/v

Cutting depth 0.3 mm.

The recommended stretching mode of the cylinder liners ensures minimal taper, ovality and roughness.

Ovality and taper not more than 0.040.05 mm.

Roughness of cylinder liner surface is not more than 2.51.25 mcm .

To stretch the cylinder liner, special cutting tools are used - hard alloy cutters.

When stretching the cylinder liners, it is necessary to monitor the wear of the cutter, since with its increased wear, the parameters of ovality, conicity and roughness will increase. The most optimal number of bore cylinders with one cutter is 5-7 pieces.

Grinding of cylinder liners. Very often, instead of stretching the inner surface of the cylinder liners, grinding is carried out on a grinding machine.

Cylinder liners are ground by means of flat abrasive wheels with grain size 40 of medium soft hardness made from white electric cord. Grinding of sleeves is carried out in two passes:

Rough grinding;

Finishing grinding;

Cooling fluid:

Water with soda ash additives 2%.

Soap.

Table speed: 0.3... 8 m/min.

Grinding wheel speed: 5600 rpm.

Part speed: 160 rpm.

Grinding wheel speed: 25... 35 m/s.

Speed of the part: 55... 65 m/s.

Transverse circle feed: 0.01... 0.03 mm.

Transverse feed at finishing pass: up to 0.005...... 0.015 mm.

Table speed: up to 0.3.. 4.5 m/min.

Grinding of cylinder liners is characterized by high rate of metal removal and provides specified high accuracy and required roughness of treated surface of cylinder liners. These parameters make it possible to achieve good honing quality and reduce the cost of abrasives.

Honing of engine cylinder liners. After stretching or grinding operations, the inner surface of the sleeve is honing. Honing is carried out on a vertical honing machine 3A83.

Honing of cylinder liners is a type of abrasive treatment of engine cylinder liners using honing heads (hongs). By honing, it is possible to obtain a hole with a deviation from the cylinders of up to 5 μm and a surface roughness of Ra = 0.630.04.

If it is not possible to restore the cylinder liner it is necessary to replace the sleeves.

Conclusion

In course work, the technological process of restoring the cylinder block by stretching was developed. The necessary equipment, technological equipment, cutting and measuring tools are selected. The part operation conditions were analyzed and the accessory for basing the cylinder block on the machine was designed.

Principle of operation

Operation of operator consists in installation of accessory for spraying of cylinder block on working table of machine. A block is placed on the pins 1 from above so that 0 of the machine is above the cylinder of the block of pins not fixed in the clamps. The operator connects the pneumatic cylinders 2 to the mains and starts the machine. Pneumatic cylinders drive rod whose wedge lowers shaft 12 downwards and drives rod with cone 8. Under the action of the cone, the rollers contact the walls of the cylinder block, therefore, the fingers with a force of = 6830 N fix the block. After the operation, the pneumatic cylinder returns the rod with the wedge to the initial position. The construction of the shaft and rod with a cone by means of spring 10 is also returned to place.

To process another type of cylinder block, it is necessary to extend the accessory and repeat the process.