1. Maintenance of gear pump shaft after wear
The wear of the shaft in the gear pump is mainly due to the friction and wear between the two ends of the shaft and the supporting needle roller, which makes the shaft diameter smaller. If it is slightly worn, the diameter of the shaft at this part can be increased by plating a layer of hard chrome, so that the shaft can be repaired. If the shaft wear is serious, it should be remanufactured from 45 steel or 40cr steel. After the shaft blank is rough and fine turned, the bearing part must be heat treated to a hardness of hrc60-65, and then ground to ensure that the surface roughness of the bearing mating part is ra. Greater than 0.32μm; the tolerance of the roundness and cylindricity of the shaft is 0.005mm; the matching part with the gear is h7/h6, and the surface roughness ra should not be greater than 0.63μm.
2. Maintenance of gear pump pump body after wear
The wear on the inner surface of the pump is mainly due to the arc-shaped working surface of the oil-absorbing section. If there is slight wear, it can be used after grinding and deburring with oilstone. The pump body is formed by casting blanks of cast iron, and new parts should be replaced when serious wear occurs. If the two end faces of the gear in the pump are repaired by grinding, the width of the pump body must also be changed to be equal to the size removed by grinding at both ends of the gear. The reprocessed two end faces of the pump body should meet the technical requirements.
3. Maintenance after wear of both end covers of the gear pump
The end cover of the gear pump is made of cast iron. After slight wear occurs, it can be ground and smoothed on a flat plate. If the wear is serious, it should be ground and smoothed on a surface grinder. The plane contact between the ground end cover and the pump body should be no less than 85%. The flatness tolerance, the perpendicularity tolerance of the end face to the hole center line, the parallelism tolerance of both end faces and the center of the two shaft holes The tolerance of the parallelism of the lines is 0.01mm. 5μm。 Surface roughness ra after grinding should not be greater than 1. 5μm.
4. Maintenance and replacement of needle roller bearings for gear pumps
After the parts in the pump are repaired, the bearing needle rollers should be replaced. The requirements for needle rollers are: the dimensional error of all needle roller diameters should not exceed 0.003mm, the length tolerance is 0.1mm, and the matching clearance with the shaft should be around 0.01mm; when assembling the needle rollers, they must be filled into the bearing shell according to the quantity requirements. The needles should be arranged parallel to each other.
