Compared with ordinary single-screw extruder and parall […]
Compared with ordinary single-screw extruder and parallel twin-screw extruder, the counter-cone twin-screw extruder (hereinafter referred to as "cone double") has a unique feeding area, a large compression ratio, and a screw in the longitudinal direction. The utility model has the advantages of higher cutting and mixing efficiency of materials and lateral direction, and is particularly suitable for producing plastic profiled materials by using high calcium filled PVC powder as raw material.
However, the attendant problem is that the barrel screw of the conical twin-screw extruder suffers from a poor service life problem due to the high productivity of the extruder.
Inorganic calcium carbonate and titanium dioxide with a small particle size and high hardness are added at a relatively high ratio of 150%, and recycled plastics with a lot of impurities are often used as the main raw material, the barrel and The screw is increasingly difficult to maintain in the solid phase friction with these materials; in order to obtain superior plasticizing ability, the material is pushed from the large inlet of the extruder designed by the super-cone to the smaller extrusion end, which is even more dramatic. This solid-phase dry friction causes the small hole end of the barrel and the small diameter section of the screw to wear particularly severely.
Since the back pressure of the screw is larger than that of the ordinary single-screw extruder and the parallel twin-screw extruder, the specially designed screw can be obtained in order to obtain superior plasticizing ability in a short moving distance in the cone double barrel. The helix angle, pitch, meshing clearance, etc., add to the shear wear experienced by the screw.
However, when the thrust bearing in the distribution box may be slightly worn due to overburden, it will also cause the screw side of the screw to rub even on the side of the adjacent spiral edge, which is even worse; we must also mention Corrosion of the chloride ions released by PVC during the plasticizing process on the barrel screw, etc., are all factors that make the life of the core components of the conical twin-screw extruder more difficult.