Work Hardening Zone of Electrical Steel in Punching Process

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.