Apparatus for extruding profiles of thermoplastic material

Claim 1

Apparatus for the extrusion of articles having widths greater than their heights, comprising, a plurality of parallel tubular barrels, an extrusion screw journaled in each barrel to extend axially therethrough, the several screws being parallel to one another, each barrel having a port adjacent one end through which thermoplastic material may be fed into the respective barrel and an outlet at its opposite end through which the thermoplastic material may be fed from the respective barrel, an extrusion head having a shaped inner passage and having at one end an extrusion orifice having a cross-section corresponding to that of the article to be extruded, a connecting portion disposed between said extrusion head and said screws and having an enlarged inner passage communicating at one end with the outlets of all said barrels to receive therefrom the thermoplastic material and communicating at its opposite end with the passage in said extrusion head to deliver into said head said material, and a plurality of tapered inserts located in the inlet portion of said enlarged passage, one between each pair of extrusion screw outlets, to direct the thermoplastic material fed into the connecting portion by each extrusion screw toward that fed by the adjacent extrusion screw to effect mixing of the thermoplastic material in the connecting portion, the sides of said inserts being inclined at an angle of less than 45* to the axes of said screws to prevent deviation of the flow direction of the thermoplastic material into the extrusion head at an angle higher than 45*, and means for driving said screws.