1. The reason why the stepper motor is equipped with a reducer
The frequency of switching stator phase current in a stepper motor, such as changing the input pulse of the stepper motor drive circuit to make it move at low speed. When a low-speed stepper motor is waiting for a stepper command, the rotor is in a stopped state. When stepping at low speed, the speed fluctuation will be significant. If it is changed to high-speed operation, the speed fluctuation problem can be solved, but the torque will be insufficient. Low speed will cause torque fluctuations, while high speed will result in insufficient torque, so a reducer is needed.
2. What are the commonly equipped reducers for stepper motors
A reducer is an independent component composed of gear transmission, worm transmission, and gear worm transmission enclosed in a rigid shell. It is commonly used as a reduction transmission device between the original drive and the working machine, playing a role in matching speed and transmitting torque between the original drive and the working machine or actuator;
There are various types of reducers, which can be divided into gear reducers, worm reducers, and planetary gear reducers according to the transmission type; According to different transmission stages, it can be divided into single-stage and multi-stage reducers;
According to the shape of the gears, they can be divided into cylindrical gear reducers, bevel gear reducers, and bevel cylindrical gear reducers;
According to the layout of the transmission, it can be divided into unfolded reducers, split flow reducers, and coaxial reducers.
The reducers equipped with stepper motors include planetary reducers, worm gear reducers, parallel gear reducers, and screw gear reducers.
What is the accuracy of the stepper motor planetary reducer?
The precision of the reducer, also known as the return clearance, is achieved by fixing the output end and rotating it clockwise and counterclockwise to produce a rated torque of+-2% torque at the output end. When there is a small angular displacement at the input end of the reducer, this angular displacement is called the return clearance. The unit is “arc minute”, which is one sixtieth of a degree. The typical return clearance value refers to the output end of the gearbox.
The stepper motor planetary reducer has the characteristics of high rigidity, high precision (up to 1 point per stage), high transmission efficiency (97% -98% per stage), high torque/volume ratio, and maintenance free.
The transmission accuracy of a stepper motor cannot be adjusted, and the operating angle of the stepper motor is completely determined by the step length and pulse number. The pulse number can be fully counted, and there is no concept of accuracy in digital quantities. One step is one step, and the second step is two steps.
The currently optimized accuracy is the gear return clearance accuracy of the planetary reducer gearbox:
1. Method for adjusting spindle accuracy:
The adjustment of the rotation accuracy of the planetary reducer spindle is generally determined by the bearing if the machining error of the spindle itself meets the requirements.
The key to adjusting the spindle rotation accuracy is to adjust the bearing clearance. Maintaining an appropriate bearing clearance is crucial for the performance and bearing life of the spindle components.
For rolling bearings, when there is a large gap, not only will the load concentrate on the rolling element in the direction of force, but it will also cause serious stress concentration at the contact between the inner and outer raceways of the bearing, shorten the bearing life, and drift the centerline of the spindle, which is easy to cause vibration of the spindle components.
Therefore, the adjustment of rolling bearings must be preloaded to generate a certain amount of interference inside the bearing, thereby generating a certain amount of elastic deformation at the contact between the rolling element and the inner and outer raceways, thereby improving the stiffness of the bearing.
2. Gap adjustment method:
The planetary reducer generates friction during its movement, causing changes in the size, shape, and surface quality of the parts, as well as wear and tear, resulting in an increase in the clearance fit between the parts. At this time, we need to adjust it within a reasonable range to ensure the accuracy of relative movement between the parts.
3. Error compensation method:
The phenomenon of offsetting the errors of the parts themselves during the running in period through appropriate assembly to ensure the accuracy of the equipment’s motion trajectory.
4. Comprehensive compensation method:
Use the tools installed on the reducer itself to ensure that the machining has been correctly adjusted and adjusted on the workbench, in order to eliminate the comprehensive result of various precision errors.
Post time: Nov-28-2023
