Work Hardening Zone of Electrical Steel in Punching Process

電磁鋼片在加工過程中會因為殘留應力以及塑性應變的產生造成電磁特性惡化進而影響馬達的整體效率。直到現在，電磁鋼片的電磁特性在加工過程中惡化的情況仍然無法預估及掌握。這是造成電動機生產後實際效率與設計效率產生落差的原因之一。 為了更加了解電磁鋼片在沖壓加工製程中造成的影響，本研究設計了一套定子槽形沖壓模具，包括了82°、86.7°、88°的夾角角度以及0.25mm、1mm、2mm、6mm的倒角半徑。 在固定槽形的條件下，分析沖頭速度、壓料板壓力、反壓板壓力以及沖頭行程模式對加工硬化面積的影響。 實驗結果顯示提高沖頭速度、沖頭行程模式為振動模式、在適當的壓料板壓力及反壓板壓力下，電磁鋼片沖壓切邊於直線部位的加工硬化面積相較於其他沖壓參數明顯降低。本實驗的最佳沖壓參數相較於本實驗的其他沖壓參數，最大可減少0.0379mm2的加工硬化面積，相當於減少56%。 另外在固定沖壓製程參數的條件下，分析定子槽夾角角度與倒角半徑對加工硬化區的影響，實驗結果顯示倒角半徑越大在倒角部位會造成越小的加工硬化面積，最大減少1.340mm2的加工硬化面積，相當於增加92%；夾角角度越大則有減小加工硬化區的效果，最大減少0.5202mm2的加工硬化面積，相當於減少36%In the punching process, the iron loss of the electrical steel sheet will increase dramatically due to the plastic strain. So far, the iron loss effect of electrical steel sheet in the punching process may be difficult to predict and control. This effect also reduces the overall efficiency of the motor. In this research, the plastic strain of electrical steel in the punching process is determined by the working hardening theory. In order to create the plastic strain, a punching mold of stator slot was designed, including 82.0°, 86.7°, 88.0° angle between two lines and 0.25mm, 1mm, 2mm, 6mm fillet radius. Under the fixed geometry, the influence of punching speed, blank holder pressure, counter punch pressure and punching mode on hardening area are measured. The results show that the hardening area is reduced by raising the punching speed, punching with vibration mode, and punching with appropriate blank holder and counter punch pressure. In addition, under the fixed punching parameters, the influence of the angle between two lines and the fillet radius of the stator slot on hardening area are analyzed. The hardening area decreases along with the larger fillet radius and the larger angle between two lines