Patent ID: 7300268

Claim:
An injection molding system for a thermoplastic resin with a blowing agent therein, said system comprising: a first mold half; a second mold half forming a cavity with said first mold half; an injection mechanism for injecting thermoplastic resin with a blowing agent into said cavity; a plurality of independently adjustable intrusion elements, each of said intrusion elements displaceable to extend into said cavity and reduce the volume of said cavity; a displacement mechanism coupled to said intrusion elements for displacement of said elements into and out of said cavity; and a controller coupled to said displacement mechanism and controlling the intrusion of said intrusion elements into and out of said cavity and controlling the depth of intrusion of said intrusion elements into said cavity; wherein, said controller controls said displacement mechanism to position a plurality of intrusion elements in said cavity prior to injection of thermoplastic resin with a blowing agent into said cavity, and said controller controls said displacement mechanism to withdraw the plurality of intrusion elements from said cavity after the injection of thermoplastic resin with a blowing agent in order for the blowing agent to expand the thermoplastic resin and entirely fill the cavity, wherein, the control of said displacement element, and the intrusion and depth of intrusion of said intrusion elements controls the density of the molded part or portions thereof.