The so-called double-alloy screw means that the product material is made of high-quality alloy steel (38CrMOALA) or chrome-molybdenum alloy steel black cross (SACM645). Refined by craftsmanship, it has the advantages of high wear resistance and corrosion resistance. It is suitable for all kinds of special engineering plastics such as glass fiber, plastic and PPA, PO, PPS, LCP, ABS fireproof, bakelite powder, magnetic powder, PC and so on.
When
conical screw barrel extruding the material, it is necessary to cool the double alloy screw, mainly to ensure the smooth production and prevent the material from decomposing due to excessive plasticizing temperature. For example, cooling in the feeding section of the screw is to prevent the temperature of the screw from being too high in this section, and to prevent the material from being attached to the thread groove of the screw due to high temperature and rotating with the screw, which affects the forward movement of the material conveying, resulting in the failure of normal production due to insufficient material supply.
The homogenization section of the screw is cooled down because the molten material in this section is subjected to large extrusion, friction and shearing, which generates a lot of heat and the temperature rises quickly. In order to prevent the material from decomposing, it needs to be cooled down. The method of cooling the screw is to pass water or oil in the screw with the axial hole to cool it as a heat transfer medium. The heat-conducting medium should be controlled at a constant temperature until it reaches the homogenization section of the screw. The screw that rotates during work needs special pipe fittings to connect with the heat transfer medium pipeline. This special connecting piece is called a rotary joint.