With the increase of service time, there will be insufficient pump oil, even no pump oil and other faults in Rexroth gear pump. The main reason is that the wear of the relevant parts is too large. The wear parts of Rexroth gear pump mainly include the driving shaft and bushing, the center hole and pin of passive gear, the inner cavity and gear of pump housing, the end face of gear and pump cover, etc. When the main technical indicators of the lubricating oil pump fail to meet the requirements after wear, it should be disassembled and decomposed to find out the wear parts and extent, and take appropriate measures to repair them.
I. Repair of worn axle and bushing
After the wear of the driving shaft and bushing of Rexroth gear pump, the matching clearance will increase, which will certainly affect the oil quantity of the pump. In this case, the normal fit clearance can be restored by repairing the driving shaft or bushing. If the wear of the drive shaft is slight, the fit clearance can be restored to the allowable range by simply pressing out the old bushing and replacing it with the bushing of standard size. If the wear of the driving shaft and bushing is serious and the fit clearance exceeds the standard, not only the bushing should be replaced, but also the diameter of the driving shaft should be increased by chromium plating or vibration surfacing, and then grinded to the standard size to restore the matching requirements with the bushing.
2. Repair of cracks in the shell of lubricating oil pump
Cracks in the shell can be repaired by welding with cast 508 nickel-copper electrode. The weld seam shall be compact and porous, and the flatness error of the joint surface with the pump cover shall not exceed 0.05 mm.
Repair of wear of driving shaft bushing hole and driven shaft hole: After wear of driving shaft bushing hole, wear trace can be eliminated by reaming method, and then matched with bushing enlarged to corresponding size. The wear of the follower shaft hole is also eliminated by reaming method, and then the follower shaft is made according to the actual size of the reamed hole.
Repair of inner cavity of pump case: After wear and tear of inner cavity of pump case, it is usually repaired by inner cavity insertion method, that is, cast iron or steel bushing is inserted after inner cavity is enlarged. After insertion, the inner chamber is lined to the required size, and the bushing extending out of the end surface is polished to make the joint surface of the inner chamber and the pump shell smooth.
Seat repair: There are two kinds of pressure limiting valves: spherical valve and plunger valve. After the ball seat is worn out, a steel ball can be placed on the valve seat, and then tapped with a metal bar until the ball valve is tightly connected with the valve seat. If the seat is worn seriously, the grinding marks can be removed by reaming and then tightened by the upper method. After the plunger seat is worn out, a little valve sand can be placed for grinding until it is tightly packed.
3. Repair of pump cover
Work surface repair: If the wear of the working surface of the pump cover is small, the wear marks can be eliminated by manual grinding method, that is, a little valve sand is placed on the platform or thick glass plate, and then the pump cover is put on the surface for grinding until the wear marks are eliminated and the working surface is smooth. When the wear depth of the working surface of the pump cover exceeds 0.1 mm, the method of turning before grinding should be adopted to repair it.
Repair of the bushing hole of the driving shaft: The repair method of the wear of the bushing hole of the driving shaft on the pump cover is the same as the repair method of the wear of the bushing hole of the driving shaft of the shell.
4. Turn-over Use of Gears
The gear wear of Rexroth gear pump is mainly in the tooth thickness part, while the wear of the end face and the top of the gear is relatively light. The gear wears unilaterally at the tooth thickness, so the gear can be turned 180 degrees. When the end face of the gear is worn out, the end face can be smoothed and the joint surface of the lubricating oil pump shell can be ground at the same time to ensure that the gap between the end face of the gear and the cover of the pump is within the standard range.