Patent ID: 6014879
Filing Date: 2000-01-18
Classification: B21D,Y10T

Abstract:
An apparatus for hydroforming a tubular metal blank comprising:a die structure having an internal die surface defining a die cavity, said die cavity being constructed and arranged to receive the tubular metal blank;a hydroforming fluid source;a hydraulically driven tube-end engaging structure constructed and arranged to engage and substantially seal opposite ends of the tubular metal blank in said die cavity, said tube-end engaging structure being movable to longitudinally compress the tubular metal blank, said tube-end engaging structure constructed and arranged to receive hydroforming fluid from said hydroforming fluid source and having a hydroforming fluid supplying outlet through which hydroforming fluid can be provided to an interior of the tubular metal blank;a hydraulically driven pressure intensifying structure movable to pressurize said hydroforming fluid provided to the interior of the tubular metal blank and thereby expand a diameter of the blank until an exterior surface of the tubular metal blank generally conforms to that of said internal die surface; anda single hydraulic power source constructed and arranged to supply hydraulic fluid under pressure to said hydraulically driven pressure intensifying structure and said hydraulically driven tube-end engaging structure, said single hydraulic power source providing said hydraulic fluid under pressure to said hydraulically driven pressure intensifying structure in order to move said pressure intensifying structure and thereby pressurize said hydroforming fluid provided to the interior of the tubular metal blank and expand the diameter of the tubular metal blank so that its exterior surface conforms to that of said internal die surface, said single hydraulic power source providing said hydraulic fluid under pressure to said hydraulically driven tube-end engaging structure to enable said tube-end engaging structure to longitudinally compress the tubular metal blank and cause metal material of the diametrically expanded tubular blank to flow longitudinally in order to replenish a wall thickness of the diametrically expanded tubular metal blank and maintain the wall thickness thereof within a predetermined range, anda valve assembly communicating said hydroforming fluid source and said single hydraulic power source with said pressure intensifying structure and said tube-end engaging structure,said valve assembly constructed and arranged to direct hydraulic fluid to selectively i) move said tube-end engaging structure into compression with said opposite ends of said tubular metal blank and ii) move said pressure intensifying structure to pressurize hydroforming fluid within said tubular metal blank so as to expand said tubular metal blank while maintaining the wall thickness of said tubular metal blank within said predetermined range,said valve assembly being operatively connected with said single hydraulic power source such that movement of said tube-end engaging structure and movement of said pressure intensifying structure can be controlled independently of one another.