1、 The problem of broken shafts caused by different centers has led some users to experience the output shaft of the drive motor breaking after the device has been running for a period of time. Why does the output shaft of the driving motor twist and break?

Upon careful inspection of the cross-section of the output shaft where the drive motor is broken, it will be found that the outer ring of the cross-section is brighter, while the color of the cross-section becomes darker towards the axis. Finally, there are broken marks (dot marks) at the axis.

This phenomenon is mostly caused by the lack of concentricity between the drive motor and the reducer during assembly. When the concentricity between the drive motor and the reducer is well ensured, the output shaft of the drive motor only bears rotational force (torque), and the operation will be smooth without pulsation. When not concentric, the output shaft of the driving motor also has to bear the radial force (bending moment) from the input end of the reducer. The effect of this radial force will force the output shaft of the drive motor to bend, and the direction of bending will constantly change as the output shaft rotates. If the concentricity error is large, the radial force will cause the local temperature of the motor output shaft to rise, and its metal structure will be continuously damaged, ultimately leading to the fracture of the drive motor output shaft due to local fatigue. The larger the error in concentricity between the two, the shorter the time it takes for the output shaft of the driving motor to break. At the same time as the output shaft of the drive motor breaks, the input end of the reducer will also bear radial forces 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, the result will also cause deformation or even fracture of the input end of the reducer or damage to the supporting bearings at the input end. Therefore, ensuring concentricity during assembly is crucial! From the perspective of assembly technology, if the drive motor shaft and the input end of the reducer are concentric, the contact surface between the drive motor shaft and the input end hole of the reducer will be very close, with no radial force or deformation space. If the assembly is not concentric, there will be a mismatch or gap between the contact surfaces, resulting in radial force and providing space for deformation.

Similarly, the output shaft of the gearbox also experiences breakage or bending, which is caused by the same reasons as the shaft breakage of the drive motor. But the output of the reducer is the product of the output of the driving motor and the reduction ratio, and the output is larger compared to the motor, so the output shaft of the reducer is more prone to breakage. Therefore, when using the reducer, users should pay more attention to ensuring the concentricity of its output end assembly!

If the problem of shaft breakage caused by insufficient output of the reducer is not due to the breakage of the drive motor shaft, but rather the breakage of the output shaft of the reducer, in addition to the poor concentricity of the reducer output end assembly, there may also be the following possible reasons. Firstly, incorrect selection resulted in insufficient output of the gearbox. Some users mistakenly believe that as long as the rated output torque of the selected gearbox meets the working requirements, it is sufficient. However, this is not the case.

Firstly, the value obtained by multiplying the rated output torque of the matched drive motor by the speed ratio should generally be smaller than the corresponding rated output torque provided by the gearbox product sample;

Secondly, it is also necessary to consider the overload capacity of its driving motor and the maximum working torque required in practical applications. In theory, the maximum working torque required by the user must be less than twice the rated output torque of the gearbox. Especially in some application scenarios, this principle must be strictly followed, not only to protect the internal gears and shaft system of the reducer, but also to prevent the output shaft of the reducer from being twisted and broken. If these factors are not taken into account, once there is a problem with the installation of the equipment, the output shaft of the reducer will be stuck by the load. At this time, the overload capacity of the drive motor will still cause it to continuously increase its output until the force borne by the output shaft of the reducer exceeds its maximum output torque, and the shaft will twist and break. If the rated output torque of the reducer has a certain margin, the situation of twisting the output shaft will be avoided.

Secondly, during the process of acceleration and deceleration, if the instantaneous impact torque borne by the output shaft of the gearbox exceeds twice its rated output torque, and this acceleration and deceleration are too frequent, it will ultimately cause the gearbox to break. If such a situation occurs, careful calculation and consideration should be given to increasing the torque margin.