Introduce the troubleshooting of stepper motor bearings
The information comes from：Internet Published on：2024-12-16
The bearings of a stepper motor are the connecting components between the stationary and rotating parts of the motor, which not only affect the operation of the motor, but also its lifespan. This will affect the product quality of the motor, so it is important to pay attention to daily use and maintenance.
1. Common Fault Analysis of Needle Roller Bearings
Needle roller bearings have low frictional resistance, high mechanical efficiency, easy lubrication and maintenance, and have been standardized, widely used in stepper motors. The common faults of needle roller bearings are as follows.
1.1 High bearing temperature
When touching the small tile cover or bearing cover seat with your hand during the operation of the stepper motor, it should be considered normal not to feel hot, otherwise it indicates that the bearing temperature is too high. The reasons for high bearing temperature are:
(1) The quality of the lubricating grease does not meet the requirements or has deteriorated, with high viscosity and excessive grease. The motor should not be added too much or too little, usually occupying about 1/3 to 1/2 of the bearing seat. More bearings with low rotational speed and light load can be added; Bearings with high rotational speed and heavy load should be added less.
(2) Inappropriate assembly of needle roller bearings, lack of relief groove between the shaft neck and bearing gear when replacing or reprocessing the shaft, or inappropriate machining dimensions of the shaft neck, resulting in improper installation of the bearing. When the bearing clearance is too small, the excessive friction loss caused by oil flow in the clearance can also cause the bearing to heat up; At the same time, when the clearance is too small, the oil volume will decrease and there will be no time to take away the heat generated by friction, which will further increase the temperature rise of the bearing. However, excessive clearance can alter the dynamic characteristics of the bearing and cause unstable rotor operation. Therefore, it is necessary to select appropriate bearing clearances for different equipment and usage conditions. Adjust the assembly process, and if it is not qualified, reassemble the bed after secondary processing.
(3) Bearing running sleeve. There are two types of bearing running sleeves, one is the running sleeve, which means there is relative displacement between the outer ring of the bearing and the bearing chamber; Another type is running the inner sleeve, which means there is relative displacement between the inner ring of the bearing and the shaft neck. The bearing will generate heat and make a "squeaking" sound when running. The processing method can be softened with adhesive or disassembled and reprocessed for replacement.
(4) Needle roller bearings lack oil. When the motor is running normally, it emits a continuous and uniform "buzzing" sound. If the bearings of the running motor make a "gurgling" sound and intermittent whistling sound, it indicates that the bearings are lacking lubricating grease. At this point, a fuel gun should be used to inject oil into the bearing through the oil hole; For the rear bearing, wait until the machine is stopped to add oil.
(5) There are 7 types of damage to needle roller bearings:
① Metal peeling off on the surface of the raceway. The rolling elements of the bearing and the inner and outer race raceways are subjected to periodic pulsating loads, resulting in contact stresses that vary periodically. When the number of stress cycles reaches a certain value, fatigue spalling occurs on the working surfaces of the rolling elements or inner and outer raceway. If the bearing load is too large, it will exacerbate fatigue. In addition, improper installation of bearings, bending of shafts, and misalignment between motor shafts and mechanical shafts can also cause rolling track peeling. The fatigue peeling of the bearing raceway will reduce the operating accuracy of the shaft, causing vibration and noise in the mechanism.
