有限元素法分析矽鋼片在沖切製程後之鐵損分佈研究

A Study on Iron Loss Distribution of Electrical Steel after Punching Process with Finite Element Method

陳沿徽(Yen-Huei Chen)

指導教授 ： 蔡曜陽

國立臺灣大學/工學院/機械工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803681

摘要

矽鋼片在沖切製程中會因為塑性變形及殘留應力等因素造成電磁特性之惡化，意即增加矽鋼片之鐵損，進而降低電動機之效率。過去對於不同沖切條件下之沖切製程對於額外鐵損值之影響，尚無一套完善的評估方法。受限於矽鋼片厚度、沖切形狀以及加工後切邊影響範圍之特性，只能以量測加工硬化程度去反推鐵損值。過去有實驗藉由應變-鐵損關係以及應變-硬度關係並證實硬度量測法可以比較出鐵損值差異，然而此實驗方法需耗費許多時間，且存在人為量測誤差。
本研究期望以有限元素法軟體ABAQUS，模擬矽鋼片沖切過程，以比較不同沖切條件下對於矽鋼片切邊應變分佈以及鐵損之影響。探討的參數有沖頭倒角大小、沖頭速度、以及沖頭行程模式。在過去受限於沖切工具和實驗時間之限制，只能粗略地比較不同沖切條件下之差異，然而利用電腦模擬可隨時修改以及計算快速的優點，可以大量比較不同沖切條件，以找出對於鐵損影響最少之沖切加工方法。模擬之製程為精密沖孔，使用中鋼生產之矽鋼片35CS250做為模擬對象。
研究結果顯示：在沖頭倒角大小方面，沖頭倒角在0.15mm對於降低額外鐵損值有最好的效果。在沖頭速度方面，沖頭速度越快越能得到較低之額外鐵損值。而在沖頭行程(振動模式)上，模擬結果顯示沖頭振動對於矽鋼片會造成多次衝擊，反而會提高應變與額外鐵損值，故振動模式對於改善切邊額外鐵損情況沒有幫助。

關鍵字

有限元素法 ； 矽鋼片 ； 伺服沖切 ； 應變分佈 ； 鐵損

並列摘要

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.

並列關鍵字

Finite element method ； Silicon steel sheet ； Servo blanking ； Strain distribution ； Iron loss

參考文獻

[1] 鄒金台，黃傳興，林俊宏，“我國感應電動機市場發展趨勢與能源效率標準提升研究”，台電節約能源論文專輯，2007。

[2] 經濟部能源局，“高效率馬達節能效益”，2010。

[3] 蘇宇庭，“節能風潮強力驅動，高效率馬達商機強強滾”，新電子科技雜誌，2014年8月。

[4] Szpunar, B, & Szpunar, J.A. Influence of Stresses on the Hysteresis Curve in Constructional Steel. IEEE Transactions on Magnetics, Vol.20, 1882–1884 (1984).

[5] Hou, C.K, & Lee, S, Effect of Rolling Strain on the Loss Separation and Permeability of Lamination Steels. IEEE Transactions on Magnetics, Vol.30, 212–216 (1994).