SU1004062A1 - Method of restoring worn surface of parts - Google Patents

Description

The invention relates to the repair of worn surfaces. Parts and can be used primarily to restore the grooves of aluminum alloy pistons.

A known recovery method. worn surfaces of parts such as reamers and measuring tools, in which the worn surface is plastically deformed by rolling rollers, electrodes, with simultaneous electric heating, ensuring the flow of metal from the non-working zone of the restored part to the worn working edges of the grooves.

However, the electric heating of the restored part by the roller-electrodes with no pulses without current does not give a quick redistribution (deformation) of the metal, since the current heats only. to the outer surface of the part. Increasing the current in order to heat the material in depth does not have an effect due to overheating and sticking of the piston material to the electrodes. In this case, to implement the method, a whole range of technical solutions is needed to eliminate defects from material sticking to the electrodes, which complicates the implementation of the method.

In addition, conventional deep electrical heating results in undesirably large deformations of the part being repaired and is associated with increased energy consumption.

The aim of the invention is to improve the quality of recovery and productivity by providing optimal modes of directional

10 deformation of the metal from the non-working zone to the zone of working worn surface.

This goal is achieved by the fact that according to the restoration method, which consists in the fact that the worn surface is deformed by rolling with rollers-electrodes with simultaneous electric heating, electric heating is carried out by current pulses

20 with a force of 3-6 kA with a pulse duration of -0.02-0.06 s and a pause duration of 0.2-0.04 s, with the rolling speed being taken equal to 0.21, 0 m / min.

25

Figure 1 shows the device dp implementation of the method, the total video | in Fig. 2, a piston with a worn krezhka is shown; in Fig. 3, electrodes with a cylindrical and spherical 30 contact surface; 4, the same with triangular protrusions on the working part and calibrating protrusions. A device for carrying out the method comprises, for example, an electrical contacting unit OKS-9862A for seam welding with a cartridge 1 for fastening a restored part, an interrupter 2 for spot and seam welding of the PSP type, a welding transformer 3 of the MT type connected to two rollers. by electrodes 4 pivotally mounted on levers 5 and 6, the ends of which are connected to the pneumatic cylinder 7, the method is carried out as follows. The recoverable part 8 is clamped in the chuck 1. Rollers electrodes 4 are brought to the surface of the shaft from a row with a worn groove 9 and they are pressed to the part by a pneumatic cylinder 7 with a predetermined pressure (12-24 kg / mm) Rollers - electrodes 4 are made of bronze (160 mm. The width of the contact surface of the electrodes is chosen based on the strength of the roller electrode electrodes and the power consumption of the electric current. The width of the electrode is less than 2 mm because of its deformation does not provide the desired performance, and a width of more than 6 mm will require Because of the high power consumption exceeding that which can be obtained on the contact machines used in the repair industry, therefore the electrode thickness is 2-6 mm. Parts 8 report rotation at a speed of 0.2-1.0 m / min Current pulses are then applied to the electrodes.The magnitude of the current depends on the width of the contact surface of the electrodes and is selected within 3-6 kA. It is experimentally established that the magnitude of the current below 3 kA does not give the desired amount of heat to effect directional deformation, and above 6 kA leads to overheating woo Moreover, the greatest effect of heating the part with current pulses is revealed when a current of 3-6 kA per 1 cm of the length of the surface processed by the electrode rollers affects .3-15 pulses: This number of pulses corresponds to the optimum range of pauses duration 0.2-0.04 s with a pulse duration of 0.02-0.06 s. In this case, if the duration of the pauses is more than 0.2 s, then the heating is insufficient for fast directional deformation of the metal, if the duration of the pauses is less than 0.04 s, then an excessive heating of the part is observed, which leads to sticking of the metal to the electrons and excessive power consumption . At the same time, if the processing speed is greater than 1.0 m / min, it is impossible to create the necessary (optimal) number of current pulses per 1 cm of the length of the workpiece with the specified pulse duration and pause (selected from the optimal range). At the same time, the heat released is insufficient for the accelerated metal redistribution process. When the welding speed is less than 0.2 m / min, the number of pulses selected from the optimal range of duration and pause is excessive, which leads to overheating of the part, with all the undesirable consequences. The pressing force of the electrodes is chosen 12-24 kg / mm. Applying a specific pressure of more than these values is impractical because of a decrease in the wear resistance of the rollers - electrodes, and at lower values, the productivity of the process of redistributing metal from the non-working zone to the working surfaces area decreases sharply. The performance of the process at these optimal modes increases dramatically. The duration of the process of metal redistribution under these conditions does not exceed 1.0 min. For example, with a processing speed of 0.6 m / min from the action of current pulses of 4 kA with a duration of 0.02 s and a pause time of 0.04 with 4 mm and a specific pressure of 15 kg / mm, the piston metal is quickly heated to a temperature favorable for plastic deformation, and is extruded by the electrode into the groove. After this treatment, in a time of 1.0 min, the groove height is restored to a nominal size of 3.0 mm with an initial size of 3.8 mm. Depending on the groove wear {the upper groove under the compression ring is subject to the greatest wear, and the maximum wear of the groove for most pistons of automotive engines does not exceed 0.3 mm). The working part of the electrodes may have a different cylindrical and spherical shape (Fig. 3). For a groove with large wear, it is advisable to make a projection on the working surface of the electrode, for example, of a triangular shape (Fig. 4). Simultaneously with the distribution: it is advisable to calibrate the groove in size, in this case, the electrode is made with a calibrating ledge (Fig. 4). The proposed method, in comparison with the prototype, allows to significantly improve the performance of restoring the grooves of pistons of connecting rod and piston mechanisms by forcing the redistribution of metal and eliminating the complex of machining operations. Annual effect

from the implementation of the method on one motor-repair enterprise is 2 5 thousand, py 6.

Claims (1)

Claim 5 The method of restoring the worn surfaces of parts, predominantly profiled surfaces of aluminum alloy pistons, is that the worn surface is deformed by rolling a roller. electric electrodes with simultaneous electric heating, characterized in that, in order to improve the quality of recovery and productivity, electric heating is carried out with current pulses of 3-6 kA with pulse duration of 0.02-0.06 s and duration of pauses 0.2-0, 04 s, with the rolling speed taken equal to 0.2-1.0 m / min. Sources of information taken into account in the examination 1, USSR Author's Certificate 61563, cl. In 23 P 6/00, 1940 (prototype).