Adaptor for extruding a plurality of streams of synthetic thermoplastic foam simultaneously from a single extruder

A synthetic thermoplastic foam extruder comprising a barrel, injection means for injecting a foaming agent into said barrel and an adapter for extruding a plurality of streams of thermoplastic synthetic foam simultaneously from said extruder, comprising:

• a body having at one end means for attaching said body to said barrel of said extruder in axial alignment therewith;
• a manifold chamber formed frontally in said one end to receive the thermoplastic mass from said barrel;
• a plurality of ducts formed in said body, radiating from said manifold chamber and opening on the opposite of said body, each of said ducts terminating with attachment means for a respective extrusion head;
• a butterfly valve in each of said ducts and means for locking each of the valves individually in a desired angular position, each butterfly valve being comprised of a disc member having a median transverse section in the form of a rhomboid with the two opposing obtuse angles rounded off and with the two opposing acute angles being not greater than 60.degree. and having a dimension measured along the axis of rotation which is 60-80 percent of the corresponding dimension of the duct whereby in the position of maximum closure said butterfly valve cuts off at least 70 percent but not more than 90 percent of the flow cross section of the respective duct.