Patent ID: 6168399
Filing Date: 2001-01-02
Classification: B29C

Abstract:
A shot piston device for molten plastic material, comprising a force-operated piston guided in a cylinder provided with an inlet and an outlet, and valve arrangements for ensuring filling of the cylinder during a return stroke of the piston and a discharge of cylinder contents during a work stroke of the piston, further comprising a differential piston arranged in front of the piston and a drive bolt for rigidly connecting the differential piston to the piston, a differential cylinder surrounding the differential piston, wherein the differential piston blocks and closes at least in an extreme rear position thereof the outlet arranged in the differential cylinder, wherein the piston has a circumference defining a groove located under the inlet and starting from an end face of the piston facing the differential piston, wherein the groove has a length shorter than a length of the piston, wherein the drive bolt has a cylindrical portion in front of the end face, and a closing ring axially slidable arranged on the cylindrical portion for closing the groove relative to an interior of the cylinder.