How to solve PVC pipe production line screw high speed extrusion of the plasticizing effect
Poor plasticization of screw in PVC pipe production line at high speed. How to solve the plasticizing effect of screw in PVC pipe production line at high speed:
In order to solve this contradiction, in the past, the general method was to increase the speed of rotating speed while reducing the depth of the screw groove. However, in this way, some plastics (such as hard polyvinyl chloride) that cannot withstand high shear are easy to decompose and cannot be processed on such telling extrusion. In order to reduce the possibility of plastic decomposition, it is necessary to strengthen the cooling of the cylinder, and in some cases to feed cold water into the screw. In this way, the dependency actually reduces the amount of extrusion, and colleagues also waste heat energy. The decrease of the depth of the screw groove H3 reduces the forward flow and thus reduces the extrusion. These phenomena are in conflict with the requirement of increasing the speed of rotation to increase the output.
In order to solve this contradiction, some plastics can also increase the temperature of the cylinder to facilitate the participation of solid phase melting. But this approach is limited. As a result, the temperature of the extrusion products will also increase, which increases the burden of the cooling system of the main and auxiliary machines. At present, the efficiency of cooling system is often a major obstacle to the improvement of extrusion productivity. The excessive extrusion temperature of colleagues will also lead to greater internal stress in the cooling process, resulting in greater deformation. It is fundamentally undesirable for those heat sensitive plastics or extrusion processes (such as cross-linking, foaming, etc.) that must be processed at lower temperatures to increase the temperature of the cylinder. Therefore, it is actually required to design the screw correctly to reduce the extrusion temperature, which is referred to as "low temperature extrusion screw" in some materials.