Patent ID: 6440353
Filing Date: 2002-08-27
Classification: B29C

Abstract:
A method of twin-sheet vacuum forming plastic articles comprising the steps of:(a) clamping two parallel sheets of thermoplastic synthetic resin in a vertical orientation to a clamping tray, said two parallel sheets in direct contact with each other about the perimeter of said clamping tray; (b) blowing air between said parallel sheets thereby creating a hollow cavity between said two parallel sheets; (c) heating said two parallel sheets to molding temperature in a vertical orientation; (d) opening a vertically oriented split mold having mold cavities with a contour conforming to the configuration of the desired article; (e) disposing said two parallel sheets between the opposing mold cavities of said vertically oriented split mold; (f) applying negative pressure to vacuum suction holes provided in the mold cavities of said vertically oriented split mold; (g) closing said split mold to form a pinch off around the perimeter of said hollow cavity thereby forming a molded hollow part still disposed within said clamping tray; (h) simultaneously inserting a blow pin into said hollow cavity and blowing compressed air into said hollow cavity to push said two parallel sheets against the mold cavities; (i) cooling said molded hollow part to a set point; and (j) opening said vertically oriented split mold and withdrawing said clamping tray.