Mechanical Principles of the Screw Extrusion Machine

Abstract

The screw extrusion machine is briefly described and submitted to a dimensional analysis resulting in generalized relations between, on the one hand, pressure developed, rate of discharge, and drive-power and, on the other, viscosity of plastic extruded, speed of machine, and a characteristic dimension.

The velocity distribution of an assumed ideally viscous so-called plastic material within a rectangular screw thread is determined, and expressions for discharge and pressure developed are derived in terms of its dimensions.

These expressions are used to discuss the effect of increasing the number of “starts” on a screw and a method of rating extrusion machines is proposed so as to allow an adequate description of the capacities of such machines.

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References

Anon. 1943 Plastics, vol. 7, p. 289, “Routine Working of Polyvinyl Chloride and Polyisobutylene”.

Anon. 1944 Engineering, vol. 158, p. 287, “Extrusion Process for Thermo-Plastic Moulding”.

Boussinesq

1868 Journal des Mathématiques Pures et Appliquées, vol. 13, series 2, p. 377, “Sur l'Influence des Frottements dans les Mouvements Réguliers des Fluids”.

Carbide Carbon

1942 “Fabrication of Vinylite Plastics by Screw Extrusion” (Union Carbide and Carbon Corporation, New York, 17).

Interman

H. K.

1943 Wire and Wire Products, vol. 18, pp. 618, 645, “Extrusion of Vinyl Compounds in the Wire and Cable Industry”.

Midwinter

E. L.

1945 British Plastics, vol. 17, p. 161, “The Extrusion of Plasticized Polyvinyl Chloride Compositions”.

Palmer

J. A.

1944 Modern Plastics, vol. 22, p. 141, “The Extrusion of Saran”.

Pierce

J. E.

1942 Modern Plastics, vol. 19, p. 55, “Extruded Tubing in War Production”.

Royle

1940 “Onward from The Beginning” (John Royle and Sons, Paterson, N.J., U.S.A.).