Coaxial extruder and extrusion method thereof

Abstract

The invention relates to a coaxial extruder and an extrusion method thereof. The coaxial extruder comprises a die, a rectifying disc, an extrusion device, a heater, a charging base and a power device, and is characterized in that the extrusion device comprises a main screw barrel, an outer screw and an inner screw; the two ends of the main screw barrel are connected with the charging base and the die correspondingly, and the outer screw is arranged in the main screw barrel and rotates; the inner screw is arranged in the outer screw and is in threaded connection with the rectifying disc; the inner screw and the outer screw are reverse in thread screwing direction, an additional thread is additionally arranged between main threads of the outer screw, the thread pitch of the additional thread is larger than that of the main threads, and an additional thread groove is formed by the additional thread and the main threads; and the bottom, at the position of the additional thread groove, of the outer screw is provided with a melt channel. The length-diameter ratio is greatly reduced, the strength of the outer screw is greatly improved, the number of heaters is reduced due to the shortened main screw barrel, and part of originally-emptied waste heat is sufficiently utilized; the material cost and the occupied area are saved, and the fusion raw material process time is shortened; the probability of decomposing of fusion materials due to overheating is reduced; and power consumption is reduced.

Description

technical field [0001] The invention relates to a coaxial extruder and an extrusion method thereof. Background technique [0002] The plastic processing process relies on the rotary motion of the screw to push the plastic raw material to move forward in a straight line, which is called the extrusion process, and plastic products of different shapes are produced through the mold. In the prior art, efforts are made to study how to efficiently transport and plasticize extrusion with the cooperation of an external heat source. Usually, in order to improve the conveying efficiency, in addition to changing the form of the screw, the most direct way is to increase the rotation speed, and the increase in the rotation speed shortens the residence time of the plastic in the screw barrel and affects the plasticizing quality. In order not to affect the plasticizing quality, it is necessary to increase the aspect ratio. The early aspect ratio was usually around 20:1 a few decades ago, ...

AI Technical Summary

Problems solved by technology

This is because the screw at the output end is rotating and cannot be directly connected to the mold

[0004] The deficiencies of the above-mentioned background technology: one is that the extruder with large length-to-diameter ratio requires higher machining precision and reduced strength of the screw and barrel; the other is that the heat treatment level of the material is required to be improved; The load on the bearing (power unit) increases; the fourth is that the long cantilever screw bears an increase in torque, so that the power and the number of revolutions cannot be greatly increased; Part of the heat energy is evacuated in vain, which increases useless work; Sixth, poor design or low processing precision will cause excessive shearing of plastics, increasing the probability of plastic molecular chain damage and generating additional shearing heat, which is uncontrollable , Improper control can cause the plastic to decompose; Seventh, there are more special-shaped mixing sections for the screw with a large aspect ratio, which not only wastes the aspect ratio but also increases the processing difficulty; Eighth, the length and depth of the screw groove in the homogenization section cannot continue increase, it is difficult to greatly increase the output limit; Ninth, the occupied space increases; Tenth, it is necessary to increase the transition connection device to connect with the mold

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