Homodromous self-cleaning double-screw extrusion machine with number of starts gradually changing and with whole-process self-cleaning function and machining method thereof

Abstract

The invention discloses a homodromous self-cleaning double-screw extrusion machine with the number of starts gradually changing and with a whole-process self-cleaning function and a machining method thereof. A screw assembly of the extrusion machine comprises a first screw and a second screw, wherein the first screw and the second screw rotate at equal speed and in the same direction and are kept engaged. The first screw comprises a first single-start thread element, a first transitional element, a multi-start thread element, a second transitional element and a second single-start thread element which are connected in sequence. The second screw comprises a first single-start thread element, a third transitional element, a multi-start thread element, a fourth transitional element and a second single-start thread element which are connected in sequence. The machining method includes the steps that materials are conveyed through rotation of the first screw and the second screw, and constituents in the materials are promoted to be mixed through a structure of gradually changing numbers of starts of threads; a runner expands, contracts and expands again in sequence, so that the materials are divided, combined and divided again in the runner for chaotic mixing; self-cleaning is achieved through mutual wiping of the first screw and the second screw.

Description

technical field [0001] The invention relates to the technical field of twin-screw extruders, in particular to a self-cleaning co-directional self-cleaning twin-screw extruder and a processing method thereof. Background technique [0002] The co-rotating twin-screw extruder with self-cleaning function is a widely used mixing processing equipment at present. This type of equipment mainly includes a barrel and two twin-screws installed in parallel in the inner cavity of the barrel. In order to produce high-shear intensified mixing, the traditional method mostly adopts a multi-thread structure, which results in the material being divided into several independent flow channels during the forward conveying process. For example, the double-start thread will divide the flow channel in the barrel into three different Connected flow channels, materials move forward along their respective flow channels during forward conveying, and will not mix with each other. In this way, the inhom...

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Problems solved by technology

In this way, the inhomogeneity of the feed composition may lead to the inhomogeneity of the material components entering different flow channels. This inhomogeneity will not be improved by mixing with each other during the forward process of the materials, which often leads to unstable product quality. The key factor

Only in the area where the kneading block is installed can it be mixed with each other, but the kneading block will bring high frictional heat generation caused by gap deformation at high speed, sudden surge of motor current, high shear, material accumulation, dead angle and self-cleaning Sexual decline and many other issues

On the other hand, due to the geometric meshing relationship, the use of multi-start threads will also lead to shallower grooves and lower output

The traditional co-rotating twin-screw extruder only provides disturbance in the meshing area to improve the mixing quality, and lacks a chaotic mixing trigger mechanism away from the meshing area. Moreover, the volume of the material in the left and right screw grooves is the same, and the tensile force field and cutting distribution cannot be introduced. Etc action mechanism, the main part of the screw channel volume lacks an effective structure for promoting mixing, so that the distribution mixing effect cannot be further improved, and the lack of tensile force field effect leads to unsatisfactory dispersion mixing

In addition, most of the processing process of the twin-screw extruder is in a non-full state, and the almost unchanged flow path leads to a great reduction in the plasticization and mixing of materials. In order to improve the mixing effect and increase the output, engineering practice adopts high speed to achieve high shear. Large length-to-diameter ratio screw prolongs the processing process, which brings many problems such as high energy consumption, low efficiency and material degradation.

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