Extrusion apparatus for the production of mixtures of molten synthetic material

Claim 1

An extrusion apparatus for extruding mixtures of molten synthetic material comprising a hollow cylinder, said cylinder including opposed first and second end regions, a screw rotatable within said hollow cylinder for conveying said mixture to be extruded from said first end region to said second end region of said hollow cylinder, flow obstruction means formed on said screw, gear pump means located on the exterior of said hollow cylinder in the region of said flow obstruction means, said gear pump means comprising a housing and two meshing gear pump wheels rotatable in said housing, said cylinder defining first aperture means disposed upstream of said obstruction means to cause the interior of said cylinder to communicate directly with the interior of said housing upstream of said gear wheels and second aperture means disposed downstream of said obstruction means to cause said interior of said cylinder to communicate directly with said interior of said housing downstream of said gear wheels, the line joining the centre of said gear wheels extending at right angles to the longitudinal axis of said cylinder and the common tangent to the pitch circles of said gear wheels lying in the same vertical plane as said longitudinal axis of said cylinder, said gear wheels each having opposed major surfaces, said major surfaces extending horizontally.