Reducer repairThe manufacturer analyzes the cause of the broken shaft

1. The broken shaft problem of different hearts

Some users have broken the output shaft of the drive motor after running the equipment for a period of time. Why does the output shaft of the drive motor twist off?

When we carefully observe the cross-section of the broken output shaft of the drive motor, we will find that the outer ring of the cross-section is brighter, and the color of the cross-section becomes darker toward the shaft center. Finally, there are broken marks (dot marks) at the shaft center. This phenomenon is mostly caused by the disagreement between the drive motor and the reducer when they are assembled.

When the concentricity of the assembly between the drive motor and the reducer is ensured well, the output shaft of the drive motor bears only the rotational force (torque), and it runs smoothly without pulsation. When it is not concentric, the output shaft of the drive motor also bears the radial force (bending moment) from the input end of the reducer. The action of this radial force will force the output shaft of the drive motor to bend, and the direction of the bend will change continuously with the rotation of the output shaft. If the concentricity error is large, the radial force will increase the local temperature of the motor output shaft, and its metal structure will continue to be destroyed, which will eventually cause the drive motor output shaft to break due to local fatigue.

The greater the error of the concentricity between the two, the shorter the time for the output shaft of the drive motor to break. When the output shaft of the drive motor is broken, the input end of the reducer will also bear the radial force from the output shaft of the drive motor. If this radial force exceeds the maximum radial load that the input end of the reducer can bear, its As a result, the input end of the reducer will be deformed or even broken or the input end support bearing will be damaged. Therefore, it is important to ensure concentricity during assembly.

Analyzed from the assembly process, if the drive motor shaft and the input end of the reducer are concentric, the shaft surface of the drive motor and the input end hole surface of the reducer will be very consistent, and their contact surfaces are closely attached, without radial force and deformation. space. However, if the assembly is not concentric, there will be no coincidence or gaps between the contact surfaces, and there will be radial force and space for deformation.

Similarly, the output shaft of the reducer is also broken or bent, and the reason is the same as that of the broken shaft of the drive motor. However, the output of the reducer is the product of the output of the drive motor and the reduction ratio. Compared with the motor, the output is greater, so the output shaft of the reducer is more likely to be broken. Therefore, when using the reducer, the user should pay more attention to the guarantee of the concentricity of its output terminal assembly!

2. Shaft broken problem caused by too small output of reducer

If the shaft of the drive motor is not broken, but the output shaft of the reducer is broken, in addition to the poor concentricity of the output end of the reducer, there are the following possible reasons:

First of all, the wrong selection caused insufficient output of the reducer. Some users mistakenly think that as long as the rated output torque of the selected reducer meets the working requirements, it is not true. The first is that the rated output torque of the drive motor is multiplied by the speed ratio, and the value obtained is in principle less than the corresponding rated output torque provided by the reducer product sample; the second is that the overload capacity of the drive motor and the requirements in practical applications should also be considered. Maximum working torque. Theoretically, the maximum working torque required by the user must be less than twice the rated output torque of the reducer. In particular, some applications must strictly abide by this criterion. This is not only to protect the internal gear and shaft system of the reducer, but also to prevent the output shaft of the reducer from being twisted.

If these factors are not taken into account, once the equipment is installed with problems, the output shaft of the reducer is blocked by the load, and the overload capacity of the drive motor will still make it continue to increase its output until the force on the output shaft of the reducer exceeds At its maximum output torque, the shaft will twist off. If the rated output torque of the reducer has a certain margin, then the bad situation of twisting the output shaft will be avoided.

Secondly, in the process of acceleration and deceleration, if the instantaneous impact torque on the output shaft of the reducer exceeds twice its rated output torque, and this acceleration and deceleration are too frequent, the reducer will eventually be broken. . If this happens, you should carefully calculate and consider increasing the torque margin.