ROLLE UND VORRICHTUNG ZU DEREN HERSTELLUNG

摘要

Apparatus for making a molded plastic roller with embedded bearings. The roller is formed directly on a bearing or the like by injecting plastic into a mold by way of an umbrella sprue. The tool parts are arranged so that the shearing surface, formed after shearing off of the sprue residue when the mold is opened, is located on the outer surface of the inner collar portion. The molding tool comprises two tool parts for forming the outer surfaces of the rolling body, at least one tool part having a molding portion for forming an annular recess in the roller, and a cylindrical tool part inserted in the bearing, or the like and having a mushroom-shaped head. A back taper of the molding portion for forming the annular recess and the edge of the head together define an annular clearance through which plastic material is injected. The head has a planar surface which covers the bearing or the like and serves as the molding surface for the sides of the inner collar portion, and a spherical surface for defining the umbrella sprue.