With the increase of use time, Rexroth gear pump will have failures such as insufficient pump oil or even no pumping oil, mainly due to excessive wear of the relevant parts. The wear parts of Rexroth gear pump mainly include active shaft and bushing, passive gear center hole and shaft pin, pump casing cavity and gear, gear end face and pump cover, etc. When the main technical indicators of the lubricating oil pump are worn and do not meet the requirements, it should be disassembled and decomposed, the wear part and degree should be clarified, and corresponding methods should be taken to repair it.
First, the repair of the drive shaft and bushing after wear
After the drive shaft and bushing of Rexroth gear pump are worn, the matching clearance increases, which will inevitably affect the pump oil volume. In this case, the method of repairing the shaft or bushing can be used to restore its normal mating clearance. If the drive shaft is slightly worn, simply press out the old bushing and replace it with a standard size bushing, and the mating clearance can be restored to the allowable range. If the drive shaft and bushing are seriously worn and the mating gap seriously exceeds the standard, not only the bushing should be replaced, but the diameter of the active shaft should also be increased by chrome plating or vibration overlay welding, and then ground to the standard size to restore the mating requirements with the bushing.
Second, the repair of the lubricating oil pump shell crack repair:
The crack of the shell can be repaired by casting 508 nickel copper welding rod. The weld shall be tight and porous, and the flatness error of the joint surface with the pump cover shall not be greater than 0.05 mm.
Repair of active shaft bushing hole and driven shaft bore wear: After the active shaft bushing hole is worn, the wear marks can be eliminated by reaming method, and then a bushing enlarged to the corresponding size is used. The wear of the driven shaft bore is also eliminated by the reaming method, and then the driven shaft is formulated according to the actual size of the reamed hole
Repair of the inner cavity of the pump casing: After the inner cavity of the pump casing is worn, the inner cavity insert method is generally adopted to repair, that is, the inner cavity is enlarged and equipped with cast iron or steel bushings. After insertion, the inner cavity is pulled to the required size, and the bushing that extends from the end face is ground off so that it is level with the joint surface of the pump casing.
Repair of valve seat: There are two kinds of pressure limiting valves: ball valves and plunger valves. After the ball seat wears out, a steel ball can be placed on the valve seat, and then the steel ball can be gently hit with a metal rod until the ball valve fits in with the valve seat. If the valve seat is seriously worn, it can be reamed first to remove the wear marks, and then use the upper method to make it sealed. After the plunger seat is worn, a little valve sand can be ground until it fits.
Third, the repair of the pump cover
Repair of the working surface: If the wear of the working plane of the pump cover is small, the wear marks can be eliminated by manual grinding, that is, a little valve sand is placed on the platform or thick glass plate, and then the pump cover is placed on it for grinding until the wear marks are eliminated and the working surface is flat. When the wear depth of the working plane of the pump cover exceeds 0.1 mm, it should be repaired by turning first and then grinding.
Repair of active shaft bushing holes: The repair of active shaft bushing hole wear on the pump cover is the same as the repair method of housing active shaft bushing hole wear.
Fourth, the use of gear flipping
Rexroth gear pump gear wear is mainly in the tooth thickness part, while the wear of the gear end face and tooth top is relatively light. The gear is worn on one side in the tooth thickness, so the gear can be turned 180 degrees to use. When the gear end face is worn, the end face can be smoothed, and the lubricating oil pump housing joint surface can be ground at the same time to ensure that the gap between the gear end face and the pump cover is within the standard range.
