Created on:2022-02-17 08:51

Repair of end face scratch of cycloidal hydraulic motor

Repair of end face scratch of cycloidal hydraulic motor

1. Introduction

Because it is a low-speed and high torque multifunctional hydraulic motor, it is widely used in construction machinery according to work needs. The flow distribution structure of a cycloidal motor is plane flow distribution, with displacement q = 245ml / R and pressure P = 15.5mpa. During use, the output is weak. After disassembly and inspection, it is found that there are three obvious scratches in the shape of hexagon ripple on the front end cover surface in contact with the motor stator and rotor end surface and on the end face of the fixed port plate.

2. Scratch and its impact on the system

The scratch on the front end cover surface is light, the scratch depth is shallow, and the shape is hexagonal corrugated (see figure x); The end face of the fixed port plate is severely scratched, with a depth of 0.1 ~ 0.2mm and a width of 0.1 ~ 0.3mm, and the shape is also in the shape of hexagonal ripple (see Fig. y).


After the front end cover surface and port plate in contact with the stator and rotor end surface are scratched, the seven closed oil cavities of the cycloidal hydraulic motor will collude with each other, resulting in serious internal leakage of the cycloidal hydraulic motor, which seriously affects the output torque of the cycloidal hydraulic motor, which is manifested in the weak operation of the cycloidal hydraulic motor.

3. Cause of scratch

The operation object of the machine is cement sand and gravel. The working conditions are very bad and there is a lack of necessary dust-proof measures, which makes the hydraulic oil seriously polluted and causes the wear and scratch of the end face moving pair of the cycloidal hydraulic motor, which is the main reason.

The cycloidal hydraulic motor is a combined structure, which is composed of a front end cover, a stator ring (the rotor is in the stator ring), a fixed port plate and a rear end cover. Between the front end cover and the fixed port plate is the stator ring, and the gap between them is very small.

When the cycloidal hydraulic motor works, the rotor rotates in the stator ring and forms a layer of lubricating oil film with the contact surfaces on both sides. When impurities enter between the two contact surfaces, one is to destroy the lubricating oil film, resulting in direct friction of the moving pair and many small wear debris; Second, if hard impurity particles are squeezed between the rotor teeth and the end faces on both sides and move with the rotor, they will cause regular wear and scratches as shown in figure X and figure y.

4. Repair method

The end face of the front end cover shown in figure x is slightly scratched, which can be repaired by grinding method, that is, apply red lead powder on the grinding platform, use No. 600 grinding sand as abrasive, grind repeatedly, and finally remove the scratch on the surface, and ensure that the surface has the lowest roughness and the highest accuracy.

The scratches on the surface of the port plate shown in figure y are deep, and the surface a is lower than the surface B. at the same time, there are sealing grooves and oil distribution channels. Therefore, attention must be paid to the dimensional requirements between them during grinding. The method is as follows:

(1) Based on plane B, measure the height difference HAB and the depth HC of the sealing groove on both sides of a and B respectively.

(2) Then take the other side of the valve plate as the benchmark to measure the thickness HP of the valve plate.

(3) As described above, grind surface B on the grinding platform until the scratch is removed.

(4) Again, measure the thickness HP1 of the valve plate based on the other side of the valve plate. The difference between HP and HP1 is the ground size h, i.e. H = hp-hp1.

(5) Take plane B as the benchmark to position on the EDM machine tool, and use the tool electrode to sink the dimension h of six planes a, so as to ensure that the height difference between sides a and B is HAB.

(6) In order to ensure the sealing, the dimension h of the sealing groove shall be sunk in the same way to ensure that the groove depth is Hg1.

Finally, after cleaning, assembly and commissioning, it is proved that the performance is good and the expected purpose of repair is achieved.

5. Measures to control wear and scratch

Replace the oil of the hydraulic system and remove the remaining impurities, particles and pollutants in the system; Reset the high-precision oil filter; Install dust-proof device for the oil tank to prevent impurities from entering the oil tank; Strengthen protective measures, check and change oil regularly.

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