Daniel L Greiwe

US Patent:

53854659, Jan 31, 1995

Filed:

Oct 1, 1992

Appl. No.:

7/955114

Inventors:

Daniel Greiwe - Elmhurst IL
Claude Powell - New London MO
Greg Pranger - North Lake IL

International Classification:

B29C 5100

US Classification:

425308

Abstract:

An apparatus for thermoforming plastic sheet material which has a frame and complementary mold halves mounted on the frame for movement toward and away from one another. The apparatus has an indexing means which moves along a vertical path to pull the plastic material through the mold and a clamping means disposed between the mold halves which operates with the mold to clamp the plastic sheet around the edges of the forming tool of one mold half. The indexing means and clamping means operate to reduce sag of the plastic material and improve uniformity of the finished article. Operation of the apparatus is enhanced by the use of air pressure, vacuum and cooling during molding and release.