Fine blanking method and device for forming friction plates with friction material layers

A fine blanking device for forming a friction plate with friction material layers, comprising:

• an upper die;
• a lower die;
• and
• a guide mechanism;
• wherein a punch is provided at the upper die, and an upper blank holder is provided at an outer circumference of the punch;
• a counter punch is provided at the lower die, and a lower blank holder is provided at an outer circumference of the counter punch;
• a bottom of the upper blank holder and a top of the lower blank holder are respectively recessed to form a ring groove;
• a buffer layer is provided inside the ring groove;
• a depth of the ring groove is larger than a thickness of the buffer layer;
• and during a fine blanking process, a vertical pressure is exerted on a base sheet by the upper blank holder and the lower blank holder for tightly fixing the base sheet, and at friction material layers of the base sheet, the vertical pressure is transformed into a flexible pressure by the buffer layer;
• and
• the buffer layer is configured to contact a surface of the friction material layers of the base sheet during the fine blanking process;
• and the ring groove is configured to act as a shelter of the friction material layers.