Patent ID: 6948350
Filing Date: 2005-09-27
Classification: B21D,Y10T

Abstract:
1. A wave-processing method for a core metal of a wet friction material comprising the steps of stamping out a material steel sheet so as to form a core metal blank having a shape corresponding to a shape of the core metal by a stamping die, and giving a wave shape to the core metal blank in a circumferential direction thereof by a special die at the same time as or after the stamping step; wherein the special die has a main punch as an upper die and a counter punch as a lower die, the main punch and the counter punch have compression faces respectively formed with the wave shape while having a micro-protrusion at a portion corresponding to a top point of the wave shape; and wherein the core metal blank is compressed between the main punch and the counter punch so that the micro-protrusion is cut into the core metal blank so as to form a notch on the core metal blank.