Vacuum pump performance of recovery and improvement

Vacuum pump performance of recovery and progress

Although the shortcomings of the vacuum pump is various, but most of the shortcomings can be eliminated. Sometimes, a new pump, for some consumer applications, still feel its limit vacuum is not high enough, maintenance workers can try to improve it as much as possible, some of the maintenance methods, steps, key parts of the analysis, can find four solutions.

Some pumps, according to their limit vacuum index, are not very low, but consumers hope that it can make some progress. How to start? The repair experience of the next 2x-30 rotary vane oil seal mechanical vacuum pump can be created by ourselves. There is no big defect in the pump when it starts and stops pumping. In terms of consumption, it is hoped that it can reach more than 75 lattice of thermocouple vacuum gauge (equivalent to 5 * 10-4 Torr measured by Maxwell’s meter), but in theory, it is not much lower than expected.

When repairing, the clearance dimensions of the main parts were measured as follows: the clearance of rotor tangent point was 0.04mm, that of high vacuum chamber was 0.07mm, that of low vacuum chamber was 0.08mm, and that of rotor was 0.02mm shorter than that of rotor. These are normal ranges.

For the repair of this kind of pump, we can start from reducing its clearance tolerance. First of all, try to change its eccentricity value: replace the middle shaft sleeve with an eccentric sleeve to reduce the upper tangent point clearance to 0.02mm; grind the pump cavity of high vacuum chamber to 0.03mm, and grind the pump cavity of low vacuum chamber to 0.04mm. After cleaning, put it upside down on the platform for assembly (without positioning pin), rotate the pump wheel by hand while assembling, and tighten the fastening screws with uniform diagonal alignment. According to experience, assuming that the rotor surface is round, when rotating the pump wheel, no matter to which point, there should be no sense of retardation and effort; but if the assembly is not correct or the rotor surface is elliptical, when rotating the pump wheel, it will have the feeling that the half round wheel is heavy and the half round wheel is light. The assembly clearance of the pump is very small. If it is not carefully assembled, it will not be installed properly. As a result of friction and heating, it is easy to be stuck or damaged in operation. So we should assemble carefully and carefully. After loading, the vacuum was measured to 82 grids by thermocouple vacuum gauge, which was equivalent to 8 * 10-3 Torr by curve, and more than 2 * 10-4 Torr measured by Maxwell’s meter. After running for a period of time, the vacuum has improved slightly.

This example shows that:

① The assembly of rotor and rotor is very important, and the clearance between rotor and pump cavity, the clearance between rotor and end cover, i.e. double clearance of high and low vacuum chamber and rotor tangent point clearance, are the key points in repair and manufacturing. Even so, but if the assembly is not correct, the material of the pump is too poor, there is a risk of jamming or grinding damage. Therefore, it should be decided by experiments in theory, not all of them should be treated.

② For the pump with poor vacuum degree, the better effect can be obtained by properly adjusting the assembly clearance and oil circuit.

③ The gap measurement should be careful and accurate. In addition to the gauge should be calibrated to meet the rule accuracy, the workpiece should be cleaned and dried, and the measurement should be repeated several times. Make a good record. Then the comprehensive pump of all aspects of the situation, determine the size of grinding. When testing the performance of the pump, the calibration of thermocouple vacuum gauge should be stopped.