Addtime： 2020-07-18 Browse times： 2808
The repair of vacuum pump axis is a common processing repair process, also known as straightening process, is the permanent bending of vacuum pump shaft core, the current straightening. The bending of the shaft core of the vacuum pump rotor is caused by the stress. When the stress is greater than the elastic limit of the shaft core material of the vacuum pump rotor, the permanent bending deformation occurs. Therefore, the straight shaft is essentially through some methods to create a stress in the bending part of the rotor shaft core to splash down or counteract the effect of the original stress.
There are many methods of straight axis, and the common methods are as follows.
1. Local heating straight axis method: the convex part of the vacuum pump rotor is prevented upward, and the local axial heating is carried out at the place with the largest bending. Heating range: axial plant is 0.1-0.15d, circumferential width is 0.3d (D is the diameter of vacuum pump shaft at heating). In order to control the heating area, the shaft is usually wrapped with thermal insulation material, and only a hole is opened at the local heating place according to the size of the heating part. The heating temperature should not exceed 500-550 degrees, which should be controlled within the tempering temperature of the material. Otherwise, the shaft core of the vacuum pump will overheat and the metal structure will change. The principle of this method is that the protruding part of the vacuum pump rotor is artificially heated, so that it is locally subjected to a compressive stress, so that the rotor is bent in the opposite direction to offset the original bending.
2. Mechanical straight axis method: that is, cold beating with twister. Place the concave part of the largest bending part of the vacuum pump rotor shaft core upward, and support the convex part. The twister is close to the concave part of vacuum pump rotor shaft core bending, and the twister is knocked with a 1-2kg hammer. The twisting should start from the center of the maximum bending point and move evenly along both sides of the circumference. The twisting length of each end face is one third of the circumference of the circle. Its principle is to twist the concave part and make some materials subject to tensile stress to elongate the fiber, so as to achieve the purpose of correction.
3. Local heating mechanical straight axis method: its straight axis principle, heating position and local heating straight axis method are basically the same. The difference is that after heating, a crooked principle is artificially applied to the protruding part of the vacuum pump rotor shaft core, so that the stress can exceed the elastic limit of the material in advance, and reach the parent of the shaft core straightening of the vacuum pump rotor.
The above three methods of straight axis are to compress the material fiber at the protruding part of the shaft, to make it press stress or to stretch the material fiber on the concave side, so as to achieve the purpose of straight axis.
The three methods have a common disadvantage, that is, after straightening, there is a large residual stress in the material of a small section of vacuum pump shaft core. These stresses determine the bending moment of the straightening rotor. When the rotor is running, the residual stress on the straightening part may lead to parameter cracks in the shaft core of the vacuum pump rotor, especially for the alloy steel shaft core.
Thermal state direct axis relaxation is a characteristic of exponential at high temperature, that is, at a certain temperature, due to the temperature effect, the stress level of metal parts is reduced, and the material presents relaxation state. The relaxation method of straight shaft is that the shaft core of the vacuum pump rotor is in a state of relaxation. Due to the low stress level, the danger of the straight shaft is also reduced. In order to make the vacuum pump rotor shaft core heated evenly, the electric induction heating method is usually used to heat the whole circumference of the bending part of the yellow drill. Generally, when the temperature reaches 580-650 degrees, the protruding side of the bending part of the vacuum pump rotor shaft core is pressurized to correct the rotor. This method can also directly use the cooling process of the rotor to return the products, so as to eliminate the residual stress.
The above-mentioned correction method of vacuum pump axis has been briefly introduced, but what needs to be improved here is that in addition to exquisite vacuum pump maintenance technology, most of the pump fault parameters are inseparable from the usual daily maintenance. If the daily maintenance is not in place, it will cause progressive damage, thus improving the failure rate. Therefore, we should improve the fault rate There is a clear maintenance plan, real-time monitoring of the pump, so as to reduce the occurrence of pump failure.
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