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Gear pump repair method
Sep 06, 2018

1. Repair of the gear pump shaft after wear

The wear of the shaft in the gear pump is mainly due to the frictional wear between the two ends of the shaft and the supporting needle, which makes the shaft diameter smaller. If it is slightly worn, the diameter of the shaft can be increased by plating a layer of hard chrome to repair the shaft. If the shaft wears seriously, it should be re-manufactured with 45 steel or 40cr steel. After the shaft blank is roughed and finished, the bearing part should be heat treated, the hardness is hrc60-65, and then ground, so that the surface roughness of the bearing mating part is not It is larger than 0.32 μm; the roundness and cylindricity tolerance of the shaft is 0.005 mm; the gear matching portion is h7/h6, and the surface roughness ra is not more than 0.63 μm.

2. Maintenance of gear pump body after wear

The surface wear of the pump is mainly the arc-shaped working surface of the oil-absorbing section. If there is slight wear, it can be used after grinding and deburring with oil stone. The pump body is molded from cast iron, and new parts should be replaced in case of severe wear. If both ends of the pump internal gear are repaired by grinding, the width of the pump body should also be changed, which is equal to the size of the gears removed at both ends. The reworked end faces of the pump body should meet the technical requirements shown in Figure 3.

3. Maintenance after the end of the gear pump is worn

The end cover of the gear pump is made of cast iron. After the wear phenomenon occurs, it can be slightly polished and flattened on the flat plate. When the wear is serious, it should be ground and flattened on the surface grinder. The plane contact between the repaired end cap and the pump body should be no less than 85%. The flatness tolerance, the perpendicularity of the end face to the centerline of the hole, the parallelism tolerance of the end faces and the center of the two shaft holes The parallelism tolerance of the line is 0.01mm. 5微米。 The surface roughness ra should be no more than 1. 5μm.

4. Repair and replacement of needle roller bearings for gear pumps

After the parts in the pump are repaired, the bearing needles should be replaced. The requirements for the needle roller are: the dimensional error of all needle roller diameter should not exceed 0.003mm, the length tolerance is 0.1mm, and the clearance with the shaft should be about 0.01mm; when the needle roller is assembled, it should be filled with the bearing shell according to the quantity requirement. The needles should be arranged parallel to each other.