Patent ID: 7669452
Filing Date: 2010-03-02
Classification: B21D

Abstract:
1. A method of stretch-forming a metal workpiece, comprising the steps of: (a) providing a heat-insulating enclosure that includes first and second aligned and opposed workpiece openings in respective first and second spaced-apart sidewalls of the enclosure between which a die with a working face having a predetermined cross-sectional profile is positioned to receive the workpiece; (b) providing first and second opposed jaws mounted on respective first and second opposed swing arms; (c) positioning the workpiece in the enclosure in forming proximity to the working face of the die with its opposite ends extending through respective ones of the first and second openings in sidewalls of the enclosure; (d) electrically insulating the workpiece; (e) gripping the workpiece in the jaws at its opposite ends; (f) resistance heating the workpiece to a working temperature by passing electrical current through the workpiece; (g) moving the workpiece and the working face of the die relative to each other while the workpiece is at the working temperature, thereby forming the workpiece against the working face of the die into a preselected form; and (h) cooling the workpiece while the workpiece is in the preselected form against the working face of the die.