How to improve the accuracy of conical twin screw extruder

Date:Jul 16, 2020

Compared with ordinary single-screw extruders and parallel twin-screw extruders, the counter-rotating conical twin-screw extruder (hereinafter referred to as "cone twin") has its unique feeding area, large compression ratio, and screw length. The shearing and mixing efficiency of the material in the upper and horizontal directions is higher, and the plasticizing ability is better. Therefore, it is particularly suitable for the production of plastic profiles with PVC powder filled with high calcium as the raw material.

However, the ensuing problem was that the barrel screw of the conical twin-screw extruder encountered a poor replacement problem due to the high productivity of the extruder. Inorganic calcium carbonate and titanium dioxide, which are not small in particle size and high in hardness, are added at a relatively high ratio, even reaching 150%. Recycled plastics that repeatedly contain a large amount of impurities are also often used as the main raw materials, barrels and screws In the solid phase friction with these materials, it is gradually unsustainable; in order to obtain more superior plasticizing ability, the material is pushed from the large inlet of the extruder designed by the super cone to the smaller extruding end, which is even more dramatic. Solid-phase coherent friction causes the wear of the small hole end of the barrel and the small diameter section of the screw to be particularly serious; the back pressure of the screw is larger than that of the ordinary single-screw extruder and parallel twin-screw extruder. It can achieve superior plasticizing ability within a certain moving distance. The specially designed screw helix angle, screw pitch, displacement clearance, etc., increase the shear stress that the screw bears; and when the thrust bearing in the distribution box is overwhelmed, it may be The presence of a little wear will also cause the screw pitch edge to even rub against the adjacent screw edge, so it is even worse; we must also mention that the chloride ions released by PVC during the plasticization process on the barrel screw Corrosion, etc..., these are the indispensable factors that cause the core components of the conical twin screw extruder to be more severe.

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