Patent Number: 6,305,201

Title: Method and apparatus for forming unobstructed holes in hollow hydroformedmetal parts

Abstract: Method and apparatus for forming unobstructed holes in a hydroformed metalpart employs a punch having a peripheral side conforming to the desiredhole shape and an end face having a central cutting edge with a high pointthat contacts on closure of a hydroforming die with an unsupported wallsection of the part initiating a stress riser therein. During forming ofthe part, the hydraulic pressure forces the above wall section outwardagainst this high point increasing the magnitude of the stress riser. Thepunch is advanced while maintaining the hydraulic pressure causing theabove high point to fracture this wall section at the stress riser and theabove cutting edge to then split and cut this wall section to formoppositely facing cut edges in this section. Simultaneously, oppositelyangled cutting edges at opposite ends of the central cutting edge and atthe punch end face periphery then cut this wall section in directions awayfrom the oppositely facing cut edges to form oppositely extending slugs.As the punch continues to be advanced, contoured portions of the punch endface with the aid of the hydraulic pressure contact the slugs to provide aseal to maintain the hydraulic pressure while bending the slugs as theyare being cut into the interior of the part. The peripheral side of thepunch with further punch movement engages the slugs with an interferencefit to maintain the hydraulic pressure and forces the slugs into positionsforming an unobstructed hole in the part while remaining integraltherewith.

Inventors: Ghiran; Mircea (Lake Orion, MI), Oberski; Paul C (Roseville, MI)


International Classification:

Expiration Date: 10/23/2013