Screw rod of single screw extruder

Abstract

The invention discloses a screw rod of a single screw extruder. The screw rod sequentially comprises a feeding section, a compression separation section and a metering section from front to back, wherein the feeding section is provided with a main thread, the compression separation section is provided with a main thread and an auxiliary thread, and the metering section is provided with a main thread. The screw rod is characterized in that a mixed section is arranged between the compression separation section and the metering section, is provided with main threads and auxiliary threads, and sequentially comprises a plurality of mixed subsections from front to back; the bottom diameters of the main threads on the odd mixed subsections gradually decrease from front to back, and the bottom diameters of the auxiliary threads on the odd mixed subsections gradually increase; and the bottom diameters of the main threads on the even mixed subsections gradually increase from front to back, and the bottom diameters of the auxiliary threads on the even mixed subsections gradually decrease from front to back. According to the screw rod provided by the invention, the bottom diameters of the main and auxiliary threads on the mixed change alternately, so that materials can be alternately compressed and relaxed, completely plasticized and uniformly mixed. Therefore, the plastic material extruded by the single screw extruder with the screw rod is high in viscosity, and a plastic product produced by the extruder has few crystal points and bubbles.

Description

technical field [0001] The invention relates to parts of an extruder, in particular to a screw of a single-screw extruder. Background technique [0002] At present, in the process of extruding plastic products (such as polyethylene terephthalate (PET) products) with an extruder, the equipment used is usually: a single-screw extruder without exhaust function, and Supporting use of crystallization drying equipment, the plastic raw materials are crystallized and dried by the crystallization drying equipment, and then sent to a single-screw extruder for extrusion processing; or a twin-screw extruder or multi-screw extruder with an exhaust structure Raw materials can be directly fed into the twin-screw extruder or multi-screw extruder for extrusion processing. [0003] When using a single-screw extruder without exhaust function for extrusion processing, the following problems often occur: 1. The melt is not mixed uniformly, so that the crystal point and air bubbles of the prepar...

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Problems solved by technology

[0003] When using a single-screw extruder without exhaust function for extrusion processing, the following problems often occur: 1. The melt is not mixed uniformly, so that the crystal point and air bubbles of the prepared plastic products (such as PET products) are relatively small. 2. In order to achieve a better plasticizing effect, the screw is required to have a larger compression ratio, which will lead to a higher temperature rise of the plastic material, so that the viscosity of the extruded plastic material is low, and the color of the obtained plastic product is yellowish ; 3. High energy consumption during the extrusion process

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