Analysis of the Causes of Broken Shaft by Gear Reducer Repair Manufacturers
1、 Broken shaft problem caused by non concentricity
Some users may experience a disconnection of the output shaft of the drive motor after the device has been running for a period of time. Why is the output shaft of the drive motor twisted?
When we carefully examine the cross-sectional area of the output shaft where the drive motor is broken, we will find that the outer ring of the cross-sectional area is brighter, while the color of the cross-sectional area becomes darker towards the axis. Finally, there are traces of breaking (dotted marks) at the axis. This phenomenon is mostly caused by the misalignment between the driving motor and the gearbox during assembly.
When the concentricity of the assembly between the drive motor and the reducer is ensured to be good, the output shaft of the drive motor only bears rotational force (torque), and the operation will also be smooth without pulsation. When not concentric, the output shaft of the driving motor also bears radial force (bending moment) from the input end of the reducer. The effect of this radial force will force the output shaft of the driving motor to bend, and the direction of the bending will constantly change as the output shaft rotates. If the concentricity error is large, the radial force causes the local temperature of the motor output shaft to rise, causing the metal structure to be continuously damaged, ultimately leading to the drive motor output shaft breaking due to local fatigue.
The greater the error in concentricity between the two, the shorter the time it takes for the output shaft of the driving motor to break. When the output shaft of the drive motor is broken, the input end of the reducer will also bear 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 withstand, the result will also cause deformation or even fracture of the input end of the reducer or damage to the input end support bearing. 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 surface and the input end hole surface of the reducer will be very close, with no radial force or deformation space. If the assembly is not concentric, there will be mismatches or gaps between the contact surfaces, resulting in radial forces and providing space for deformation.
Similarly, the output shaft of the gearbox also experiences breakage or bending, which is due to the same reason 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, which is greater than the output of the motor, so the output shaft of the reducer is more easily broken. Therefore, when using a reducer, users should pay more attention to ensuring the concentricity of its output end during assembly!
2、 The problem of shaft breakage caused by low output of the gearbox
If it is not the drive motor shaft that is broken, but the output shaft of the reducer that is broken, in addition to the poor concentricity of the output end assembly of the reducer, there are also several possible reasons:
Firstly, the incorrect selection resulted in insufficient output of the equipped reducer. Some users mistakenly believe that as long as the rated output torque of the selected reducer meets the working requirements, it is not the case. One is to multiply the rated output torque of the matched drive motor by the speed ratio, and the value obtained should be generally smaller than the corresponding rated output torque provided by the reducer 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 2% of the rated output torque of the gearbox
