Bearing is a key part to support the normal operation of the motor, in addition to the manufacturing process control, the design and configuration of the motor bearing is very important, such as vertical motor and horizontal motor should choose different bearing configurations, different speed requirements of the motor should also choose different bearings.
1 configuration of Horizontal motor bearings
A ball bearing and a column bearing should be used as far as possible at both ends of the horizontal motor. At present, the domestic 2-pole small and medium-sized motor uses more than two ball bearings, although some manufacturers have made some adjustments to the tolerance zone of the bearing indoor diameter in the direction of the clearance, in order to alleviate the problem of the ball being squeezed after the bearing is heated. However, because the expansion coefficient of the bearing jacket is larger than that of the cast iron parts bearing the bearing chamber – the end cap or the bearing sleeve, and the temperature at the bearing jacket is also higher, the bearing jacket can slide a little bit axially in the bearing chamber at room temperature, but the bearing may not be able to move after being heated during operation. This is the main reason why the bearing life is short and easy to heat when two ball bearings are used. After the temperature rise test of the motor with two ball bearings, the motor is stopped to measure the temperature rise, and sometimes the bearing of the motor is burned out for the second time, the reason is that the clearance of the ball bearing can not bear the thermal expansion and cold contraction of the rotor, and the jacket can not creep in the bearing room, so that the ball can bear the larger axial force caused by.
If one ball bearing and one column bearing are selected, the above problems can be avoided. With a better motor factory in the H560 frame number in the 2-pole high-voltage motor, from the original use of 2 ball bearings to a ball bearing, a column bearing, the late operation effect is very good. In addition to the replacement of bearings according to the regular maintenance cycle, there is no fault during normal operation. And the temperature measured at the bearing is only 20℃. This is the first successful case of changing the traditional 2 ball bearings to one ball bearing and one column bearing for 2-pole motors in China, and it has been gradually promoted on explosion-proof motors.
In order to solve the problem of heat and noise after the limit speed of ball bearings is replaced by column bearings, light series column bearings can be used, and it is placed on the external fan end, the cooling condition is good, and the bearing noise can also be submerged by fan noise. If the power of the 2-pole motor is larger, the bearing type is larger, and the light series of column bearings are difficult to meet the requirements of the limit speed, the bearing grease can also be changed to thin oil.
2 Configuration of vertical motor bearings
When the vertical motor is used to drag the barrel pump in the petrochemical system, due to the instantaneous upward axial force of the multistage barrel pump at starting, coupled with the requirements of transportation, and in order to eliminate the damage caused by the thermal expansion of the rotor to the bearing, the vertical barrel pump motor (both 2 poles or 4 poles), the upper bearing of the motor should be selected two single-row centripetal thrust ball bearings. Column bearings for lower bearings should still be selected as light series. In order to prevent damage to thrust ball bearings, the two bearings should have a pre-added axial force on the bearing jacket. The size of the force is to ensure that the bearing is not damaged by the reverse axial force from the shaft extension end to the non-load end during transportation and starting.
Post time: May-30-2024
