Yielding Plunger Patents (Class 425/DIG131)
  • Patent number: 4885317
    Abstract: Polymerized foam material in flat billet form is enclosed in a heat-retaining envelope and heated to forming temperature then promptly loaded into an innovative unheated forming press and accurately formed before cooling below forming temperature. The heat-retaining envelope has an expansive skin on one side and a contractive skin on the other side to facilitate bending without wrinkling or other distortion. The forming press utilizes a rigid male form punch and a spring-tensioned elastic belt, supported on a pair of variably-spaced rollers, initially presenting a flat compliant surface upon which the heated workpiece is placed. Pressure from the form punch progressively deflects the workpiece and the belt, which becomes a compliant mold member conforming itself and the workpiece progressively around the form punch to yield an article of required carved shape, free of wrinkles or tool creep distortions.
    Type: Grant
    Filed: July 21, 1988
    Date of Patent: December 5, 1989
    Assignee: Northrop Corporation
    Inventors: Joe K. Thein, Flerida B. Uldrich