Deep drawing plastics sheet for automobile mouldings - using hinged frame to stretch sheet to shape of hollow pattern

摘要

Stepwise, continuous deep drawing of a plastics sheet held in a frame by vacuum forming gives articles having a concave or similar surface; the moulding being used later as a stiff shell to be backed by a foam plastics layer. The supporting frame for the sheet has hinges at the positions corresp. to the hollow region of the pattern; the hinges are used to enable the supporting frame to be depressed to correspond approx. to the surface shape of the pattern. When heating to 150 degrees C is used for the sheet, the hinges are pref. carried on a pair of rails, and the pattern is pulled in below them after the sheet has been heated; the ends of the frame are then raised, esp. using piston-cylinder units, and vacuum is finally applied to pull the sheet down onto the pattern. Subsequent deforming of the sheet to the curved or hollow pattern is considerably reduced, giving a much better prodt., esp. for dashboards, transmission housings, etc., for cars.