Screw for molding thermoplastic resin having a stress relaxation section
AssigneeIdemitsu Petrochemical Co., Ltd.
InventorToyokazu Takubo
Life of this patent
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Abstract
This invention relates to a screw used in an equipment for molding thermoplastic resin, in which a mixing section is provided at a position adjacent a shearing section, and the pitch of a stress relaxation section is preset to the pitch, at which satisfactory kneading can be performed without giving high shearing to the resin. With this screw, even if high-speed extrusion molding is performed, the pressure of resin is not fluctuated, molded parts can avoid lowered material quality and outstanding molded parts can be provided.
Claims17
A screw for molding thermoplastic resin, comprising:
- a feed section, a compression section which is a relaxed compression section having a compression ratio in the range of 3 or less, a shearing section and a stress relaxation section being successively provided from a resin feed side to a resin extrusion side, and a mixing section being provided intermediate said shearing section and said stress relaxation section, the length of said shearing section being in the range of 0.2-2 times the diameter of said screw, the length of said stress relaxation section being in the range of 4-15 times the diameter of said screw, and a ratio L/D between the total length L and the diameter D of said screw being in the range of 15-40.
A screw for molding thermoplastic resin, comprising:
- a feed section, a compression section, a shearing section and a stress relaxation section are successively provided from a resin feed side to a resin extrusion side, said screw having at least one thread in each of said sections, the pitch of at least part of said thread in said stress relaxation section being in the range of 0.3-0.8 times the pitch of the thread in at least one of said feed section and said compression section, and a ratio L/D between the total length L and the diameter D of said screw is in the range of 15-40.
Dependencies are inferred from the claim text.