Process for fabricating plastic foam sheet material with compound radius

Abstract

A high speed plastic-forming process forms a curved wall section with a compound radius along the outer edge of a sheet of plastic foam material. The process includes first die cutting the flat sheet material to a shape having an initial edge curvature, followed by securing the die cut piece to a carousel which passes the curved outer edge section of sheet material past heaters that controllably heat the top and bottom surfaces of the moving curved edge section. The carousel then passes the pre-heated edge section into contact with an elongated stationary curved forming shoe along the outer edge of the carousel to progressively bend the pre-heated section into a curved wall section of compound radius. The carousel then passes the formed wall section into contact with an elongated stationary curved cooling rail extending around most of the outer edge of the carousel downstream from the forming shoe. The cooling rail holds the sheet material in the curved shape while the temperature is reduced sufficiently to stabilize it in a set configuration. The heating zone length and temperature and the relative lengths of the forming shoe and cooling rail are proportioned to allow continuous feeding of die cut pieces onto the carousel, with finished parts being formed and removed after one revolution of the carousel.