Analysis of Broken Shaft of Punching Machine
Abstract
The punching machine is an important classical machinery equipment, widely used in machinery manufacturing enterprises. During the punching machine operation, an accident broke the punching machine shaft, which caused an unexpected production accident. This article briefly introduces the process of the punching machine shaft accident, and analyzes the cause of the shaft breakage, in order to put forward a countermeasure to prevent similar accidents.
Keywords: Punching machine; Shaft; Broken.
1 Introduction
Punching machines are widely used in the processing of automotive body panels and sheet metal components in the manufacturing industry. Its main functions are punching and bending processing, features high productivity and low failure rate [1]. However, during the normal operation of the punching machine, the shaft of the punching machine suddenly breaks. This reduces production efficiency, causes significant economic losses and endangers personal safety. In this paper, the cause of the punching machine shaft breakage is analyzed, and a countermeasure is proposed to prevent similar accidents from happening again.
2 Accident Information Collection
The shaft of the punching machine accident occurred at a sheet metal processing factory. The shaft of the punching machine is made of high-quality alloy steel and undergoes further heat treatment such as quenching and tempering. The output torque of the punching machine is around 55 Nm, and the maximum punching force applied to the shaft is 25 t [2].
Grooves were found on the shaft before breakage. The material of the shaft was changed from 20CrMnTi gear steel to 45# steel after the accident. The shaft was cut open and observed. It was found that there were cracks on the surface of the shaft near the side hole and the lower end of the side hole had cracks. The front and back face of the lower end of the side hole were bent, indicating that the shaft was deformed by hitting.
3 Analysis of the Accident
The possible causes of the shaft breakage may be the quality of the shaft itself or the working conditions.
3.1 Qualitative analysis
Qualitative analysis involves analyzing the quality of the shaft material and the heat treatment process. 20 crmnti gear steel and 45# steel are both high quality steel materials, and the hardening process is complete. It is unlikely that the shaft material was the primary cause of the broken shaft.
3.2 Working condition analysis
The pressure applied to the shaft during the working process is the main cause of the breakage. If the pressure is too large, it will cause the shaft to bend and result in the breakage. When the shaft is bent beyond its flexibility limit, there will be permanent deformation and the shaft will break when subjected to further loads. The overloading caused the shaft to break consequently.
4 Countermeasures
After the analysis of the punching machine shaft breakage is completed, the corresponding measures need to be adopted to ensure the safe operation of the punching machine.
4.1 Proper selection of punching force
To ensure the safe operation of the punching machine, the selection of the punching force needs to be reasonable. The design punching force should not exceed the specified upper limit of the punching machine, and the actual punching force should not be too large, which is mainly determined according to the thickness and hardness of the sheet material [3].
4.2 Shaft strength improvement
The overloading of the punch is the main cause of the shaft breakage. The shaft strength should be improved to meet the requirements of the application, and appropriate strengthening measures should be adopted in the design, such as increasing the wall thickness and size of the shaft, and adjusting the material consistency to reduce stress concentration [4]. Moreover, it is also necessary to improve the design process through analysis and calculation, and to develop new materials with higher bearing capacity to better ensure the strength of the shaft.
5 Conclusion
In this paper, based on the accident analysis of the punching machine shaft, the primary cause of the shaft breakage was identified. The punching force applied was too large, and the inherent strength of the shaft was not enough to carry the load. In order to prevent similar accidents from occurring, reasonable selection of punching force and strengthening of shaft strength should be taken to ensure the safe operation of the punching machine.
