Michael N Hritz

US Patent:

42920159, Sep 29, 1981

Filed:

Mar 12, 1979

Appl. No.:

6/019836

Inventors:

Michael Hritz - North Royalton OH

International Classification:

B29C 504

US Classification:

425 73

Abstract:

A method and apparatus for the rotational molding of thin-walled articles. The method is comprised of the steps of introducing a predetermined amount of plastic material into a mold, rotating the mold about a first axis at a predetermined speed, while simultaneously rocking the mold through a selective arc about a second axis which is normal to the first axis, heating the mold for curing the plastic material during the rotation and rocking, and cooling the mold and plastic material whereby the plastic material is molded to form a thin-walled object in conformance with the interior surface of the mold. The rotational molding apparatus is comprised of a heat insulating housing comprising a bottom half and a top half which may be disassociated for access to the interior of the housing. The interior of the housing contains a first frame which may be rocked about a first axis and a second mold-carrying frame which is attached to the first frame and rotates about a second axis normal to the first axis. Motors mounted exterior of the housing and operably connected to each of the frames cause the rotation and rocking of the frames.