Patent ID: 11890661
Assignee: HEFEI UNIVERSITY OF TECHNOLOGY
Field: Machine tools (Mechanical engineering)
Classification: CPC B | IPC B

Claim 2:
3. The method of claim 2, wherein each distributed magnetizing and demagnetizing circuit comprises four solid-state relays Ki, where i∈{1, 2, 3, 4}, Ki is in a disconnected state in an initial condition for stamping the sheet material, and outputting at least one of the switching quantity signal, the pulse signal, and the PWM signal to the distributed magnetizing and demagnetizing circuits corresponding to the plurality of blank holder areas based on the error comprises:
outputting the pulse signal to a solid-state relay K3 to cause the solid-state relay K3 to be on or off cyclically with a fixed duty cycle, wherein a frequency of the pulse signal is greater than 5 times a frequency of the PWM signal;
adjusting a duty cycle of the PWM signal based on the error to cause a solid-state relay K4 to be on or off cyclically with a flexible duty cycle, wherein an absolute value of the error is proportional to the duty cycle of the PWM signal;
outputting a positive switching quantity signal to a solid-state relay K1 in response to the error being greater than 0, to cause the solid-state relay K1 to be on to magnetize the distributed magnetizing and demagnetizing circuit; and
outputting the positive switching quantity signal to a solid-state relay K2 in response to the error being less than or equal to 0, to cause the solid-state relay K2 to be on to demagnetize the distributed magnetizing and demagnetizing circuit.