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1、 Assembly method of rolling bearing

The assembly of rolling bearing of water ring vacuum pump depends on the interference between rolling bearing and journal or bearing hole. When the interference is small, the press in method is used for assembly, and when the interference is large, the hot assembly method can be used.

When the press in method is adopted, copper rod and hammer can be used to knock symmetrically on the inner race with interference in a certain order. In addition, the sleeve made of soft metal can be used to drive in by hand hammer or press.

When the hot assembly method is adopted, the bearing shall be heated in the engine oil, and the temperature of the oil shall be below 100 ℃. After being taken out of the oil, it shall be immediately set on the journal. The advantage of hot charging method is that it does not destroy the matching property.

2、 Assembly of coupling

The coupling is a device that connects the driving shaft and the driven shaft together. It is divided into motor coupling and pump coupling. During installation, the two halves of the coupling must be concentric, and there must be a certain amount of axial clearance between the two ends of the coupling. Otherwise, the operation and service life of the machine will be seriously affected. Therefore, the alignment of the coupling is an important part of the assembly work.

1. Different axial requirements of coupling

The axis of pump shaft and motor shaft should be in the same straight line. If there is a certain inclination (i.e. the so-called different axial degrees), the machine will run unsteadily, produce vibration and noise, cause bearing wear, and affect the life of the machine. Therefore, when installing the two half couplings, there should be different axial requirements.

Because the size of the outer circle of the two coupling halves is equal, different axial degrees can be checked through the outer circle. The inspection method is to place a ruler on the outer circle of the two coupling halves, and observe whether the ruler is close to the outer circle of the two couplings. If it is closely attached to one coupling and there is a gap with the other coupling, it means that the two couplings are not concentric and need to be adjusted. In this way, check the upper, lower, left and right positions until they are all close to each other and there is no gap.

The different axial degrees of coupling shall not exceed 0.05mm.

2. Axial clearance requirements of coupling

In order to avoid the collision between the two couplings during operation, the axial clearance between the two couplings should be uniform. Clearance size can be checked by feeler gauge, generally 4 ~ 6 mm.

Assembly of impeller of water ring vacuum pump

If the impeller is assembled correctly on the shaft, the volume efficiency of the water ring vacuum pump can be guaranteed and the vibration can be prevented.

After the impeller is assembled on the shaft, its end face runout must be within the allowable range. The axial clearance between impeller and front and rear covers is very small (for example, SZ-1 and SZ-2 are 0.15 mm, sz-3 are 0.20 mm, and SZ-4 are 0.25 mm). Excessive end face runout will lead to eccentric wear between impeller and front and rear covers, which not only promotes pump heating, increases power consumption, but also increases end clearance, increases gas leakage in compression zone through end face clearance, and reduces volumetric efficiency.

In addition to the shape error of the end face, the size of the end face runout mainly depends on whether the impeller is correctly assembled on the shaft. Therefore, the force should be even during assembly, and the shaft and hole should not be damaged. After the impeller is installed on the shaft, in addition to the end face runout should meet the requirements, but also check the imbalance of the impeller.

Although the impeller is required to be symmetrically distributed in the design, the center of gravity and rotation center are not coincident due to other defects such as air hole and shrinkage cavity in casting and uneven mass distribution of non machined parts, resulting in additional centrifugal force or force couple when the impeller rotates, causing vibration of the unit. This kind of vibration is very harmful. It makes the parts inside the pump loose, and the force acting on the bearing is uneven, thus causing eccentric wear of the bearing and premature damage. In addition, if the vibration frequency is equal to the natural vibration frequency of the pump or foundation, resonance will occur, and the water ring vacuum pump unit or foundation will be damaged. Therefore, measuring and eliminating the unbalance force of impeller is one of the most important steps in assembling and repairing water ring vacuum pump.