Patent ID: 8382464

Claim:
A die system for extruding a cellular, foamed extrudate from an extruder, the extruder including an exit opening, and forming a molded extrudate product having a substantially uniform cell structure from a cellulosic fibrous-polymer composite material, comprising: a. an adapter die plate, removably connected to the extruder for receiving the extrudate from the exit opening of the extruder, the adapter die plate including a front opening, a rear opening and a flow channel connecting the front opening to the rear opening, wherein the flow channel of the adapter die plate decreases in cross-sectional area from the front opening to an intermediate portion of the flow channel between the front opening and the rear opening, and increases in cross-sectional area from the intermediate portion to the rear opening; b. at least one transition die plate adjacent the adapter die plate, the transition die plate including a front opening, a rear opening and a flow channel connecting the front opening to the rear opening; c. a flow restriction die plate adjacent the transition die plate, the flow restriction die plate having a front opening, a rear opening and a flow channel connecting the front opening to the rear opening, wherein the flow channel includes a plurality of stranding channels to divide the flow of extrudate, wherein the stranding channels have a diameter and length to provide sufficient resistance pressure to the extrudate flow such that resistance pressure of the extrudate entering the adapter die plate is increased, wherein the increase in resistance pressure alters extrudate entering the adapter die plate such that the extrudate entering the adapter die plate is characterized by increased uniform cell structure and lower density, wherein the flow channel of the transition die plate is shaped such that equal amounts of extrudate are delivered to the stranding channels; d. a compression die plate adjacent the flow restriction die plate and comprising a front opening, a rear opening and a flow channel, wherein the compression die plate front opening is adjacent the flow restriction die plate rear opening, wherein the compression die plate flow channel is shaped to reform the extrudate into a single stream of extrudate and wherein further the compression die plate flow channel is shaped to maintain melt pressure at a level which will prevent premature development of cells in the material; e. a shaping die plate adjacent the compression die plate and comprising a front opening, a rear opening and a flow channel, wherein the shaping die plate front opening is adjacent the compression die plate rear opening and wherein the shaping die plate flow channel is shaped to approximate the shape of the desired profile of a final extruded product and to control rate of cell development and expansion so that large numbers of uniform cells are produced, and wherein a ratio of a volume of the flow channel of the at least one transition die plate to a volume of the flow channel of the shaping die plate ranges from 1.05:1 to 3.45:1.