Patent ID: 7415859

Claim:
A method for forming a blind hole in a sheet of material, comprising; placing a sheet material between a first upper die and a first lower die; punching a recess punch into a through opening in said first upper die, to force a portion of said sheet material against a recess pad that inserts into a portion of a through opening of said first lower die to form a recess segment; placing said sheet material between a second upper die and a second lower die; punching down a tapered punch into a through opening of said second upper die, scraping a portion of material along a sidewall of said recess segment downwardly; compressing said portion of material onto said recess segment of said sheet material against a support pad that inserts into a portion of a through opening of said second lower die to form a material channel between said sheet material and recess segment of said sheet material, wherein said tapered punch has an edge that inclines inward, and edges surrounding a top surface of said through opening of said second lower die are chamfered; and defining a sidewall at an open end of said recess segment with a support portion of said support pad while a profiling pin of said support pad determines a height of said sidewall of an open end of said recess segment to form a blind hole on a bottom surface of said recess segment.