| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 106 === The iron loss of the silicon steel sheet increase due to the plastic strain and residual stress after punching process. This effect also reduces the efficiency of the motor. In the past, there is no method to realize how the punching process under different punching conditions affect the extra iron loss value. Due to the limitation of the thickness of the silicon steel sheet, punching shape and the influence area in the cutting edge after punching, the iron loss value can only be estimated by measuring the value of work hardening. In the past, it has been experimented that the difference of iron loss value can be compared by using the strain-iron loss relationship and the strain-work hardness relationship. However, it takes a lot of time and there is personal error in the test.
In this study, we simulate the punching process of silicon steel sheet by the finite element method software-ABAQUS. With this software, we can compare the strain distribution and the change of iron loss in the cutting edge of silicon steel sheet made by different punching condition. The parameters discussed include the chamfer size of punch, punch speed, and punching with vibration mode. Due to the limitations of punching tools and experiment time, we could only roughly compare the difference between different punching condition before. But now, with the advantage of computer simulation, we can modify the model at any time and calculated quickly, and we can also get a large number of data. The simulation process is fine blanking, take silicon steel sheet 35CS250 as simulation object.
The results show that in terms of punch chamfer size, the punch chamfer in the range of 0.15mm is the best for reducing the extra iron loss. In terms of punch speed, if the punch speed is much more fast, we will get a lower extra iron loss. In terms of vibration mode of punch, the simulation results show that the punch vibration will cause multiple impacts on the silicon steel sheet, it will increase the strain and the extra iron loss in the cutting edge, so the vibration mode does no help to improve the extra iron loss of the cutting edge.
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