Olaf E Larsen

40254801, May 24, 1977

Nov 19, 1975

5/633313

Olaf E. Larsen - Dallas TX

Phillips Petroleum Company - Bartlesville OK

C08L 9106

260 285A

A blend of polymer fluff, at least one dry additive and a slip agent is prepared by compounding the polymer fluff and the dry additive, introducing this mixture to a disc mill while simultaneously introducing the slip agent to the disc mill and thoroughly mixing the polymer fluff, additive and slip agent in the mill.

44026587, Sep 6, 1983

Sep 21, 1981

6/304234

Olaf E. Larsen - Dallas TX

Phillips Petroleum Company - Bartlesville OK

B29D 2300

425192R

A die assembly for the extrusion of thermoplastic pipe from a plastic exhibiting an appreciable amount of memory and thus having an elongated heated portion defined by an elongated outer bushing ring with an inside diameter substantially equal to the nominal outside diameter of the pipe to be produced and an inner mandrel ring having an outside diameter smaller than the inside diameter of the bushing ring and disposed within the bushing ring to form an annular extrusion channel, the essentially straight portion of the extrusion channel defining the land length of the die and the width of the extrusion channel defining the die opening of the die, the improvement comprising a mandrel formed in two sections, including a longer upstream section, fixedly mounted in the die and having a fixed mandrel outside diameter and a downstream mandrel section removably mounted in the die as an extension of the upstream section and replaceable by downstream mandrel sections of equal length but different mandrel outside diameters. The improved die assembly is capable of producing a given diameter pipe having a plurality of different SDR Ratings which closely approximates a predetermined land length to die opening ratio for each of the different SDR ratings, thereby eliminating the necessity of providing a complete new die assembly for each different SDR rating desired.

41734467, Nov 6, 1979

Jul 21, 1977

5/817766

Olaf E. Larsen - Dallas TX

Phillips Petroleum Company - Bartlesville OK

B29D 2304

425380

In the extrusion of plastic pipe in which polymer flows from an extruder into a spreader cone, through a plurality of channels in a distribution plate and through a choke passage for blending the plurality of flow streams from the individual channels in the distribution plate to form the sidewall of an extruded pipe, improved blending and welding of the polymer flow is accomplished by incorporating in the outer wall of the choke passage a plurality of elongated cavities with each cavity diminishing in depth and width from its upstream end to reach zero depth and width as the passage stretches downstream across the line of polymer flow. In preferred embodiments the cavities are tear-shaped with wall space in between and overlap at least an end of the nearest passage on either side as viewed in the direction of polymer flow.