What Are The Reasons And Measures For The Fracture Of The High-Speed Shaft Of The Reducer?
According to practical experience in production, the high-speed shaft of the hard-toothed reducer is prone to fracture. One is at the mating end face of the coupling and the high-speed shaft, and the other is at the mating end face of the bearing coaxial. So what is the reason for the fracture of the high-speed shaft?
Stress concentration in the keyway
Observing many broken shaft fractures with keyways, we can see that the earliest fatigue cracks often occur at the sharp corners of the flat keyways. It is obvious that the stress concentration of the keyways and the reduction of the cross-sectional area of the shaft affect the strength of the shaft.
Coaxial interference fit of the coupling
When the fractured part of the shaft happens to be the edge of the coaxial interference fit of the coupling, the interference fit has a great influence on the strength of the shaft.
Problems in the installation and use of the reducer
An old and difficult problem in the design of hard-toothed reducer is that the shaft diameter of the motor and the reducer is seriously mismatched, and the reducer shaft is much thinner than the motor shaft. Generally, the diameter of the reducer shaft is about 3/4 to 1/2 of the motor shaft, so the bending stress on the reducer shaft is much larger than that of the motor shaft, and it is inevitable that the reducer shaft will break.
Radial stiffness of the coupling on the shaft
The radial stiffness of the coupling refers to the radial force required for each unit of radial displacement Δy between the two shafts of the coupling. The greater the radial stiffness, the greater the radial force, and the greater the adverse effect on the strength of the connecting shaft. Non-metal elastic element flexible couplings, such as elastic sleeve cylindrical pin couplings, plum blossom couplings, and tire couplings Shafts, etc., have a small radial rigidity.
Unbalance of rotating parts on shaft
If the static or dynamic balance of the rotating parts is not good, the rotating parts will generate centrifugal force, which will increase the additional stress of the shaft, thereby affecting the strength of the shaft.
The mass gravity of the coupling and brake on the shaft
The high-speed shaft of the reducer generally has a coupling, or the brake wheel of the brake. Its own weight has little effect on the strength of the high-speed shaft of the soft-tooth surface reducer, because the size of the shaft of the reducer can be Make it bigger. However, for the hardened gear reducer, due to the limitation of the size of the gear on the high-speed shaft, the size and safety factor of the high-speed shaft are relatively small, and the mass gravity of the coupling or brake wheel can be the same as the above-mentioned centrifugal force. Superimposed, in this case, the influence of the quality of the coupling or brake wheel on the strength of the high-speed shaft cannot be ignored.
The main measures to prevent the high-speed shaft from breaking
1. Strictly control the processing quality of the keyway, especially the fillet radius r at the bottom of the groove, and take the largest value according to the standard as much as possible; the keyway without rounded corners cannot be used.
2. Couplings, brake wheels, etc. installed on the high-speed shaft should undergo static balance or dynamic balance tests to avoid excessive additional centrifugal force.
3. Reduce the weight of the coupling and brake wheel as much as possible.
4. Couplings and brakes whose manufacturing quality does not meet the technical requirements cannot be used.
5. The bottom surface of the base of the reducer and the motor should preferably be a processed plane; the adjusting shim should be flat, preferably with positioning measures
6. Regularly check whether the anchor bolts are loose, broken, etc. The purpose is to prevent the motor or reducer from moving after the equipment has been running for a period of time, damaging the adjusted coaxiality.
7. The most important thing is to control the coaxiality of the reducer installation. When installing the reducer, a professional who has mastered the technology should be dispatched to be responsible for adjusting and testing the coaxiality of the motor and the reducer. Using a fast, simple and economical laser centering device, it may have a good effect to detect the centering of the two axes.
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