The extruder screw and barrel are the key parts of the extruder and their combination is related to the working quality of the extruder, the plasticizing ability and production efficiency of the material. So when the extruder screw and barrel wear seriously will affect the output of extrusion. Therefore, the understanding of the screw is very important. Today, we will mainly introduce the screw rod of extruder.
Extruder screw is the most important part of extruder equipment which can directly influence the using effects and output of extruder. The principle of extruder screw design is: the extruder rod of screw rotates in the barrel under a high temperature and high pressure torsion. Because it has to push the materials forward strongly in the rotation, it also need to bear the strong friction and corrosion gas erosion of plastic decomposition, the extruder screw material must have high mechanical strength and the ability to endure the great torsion torque and stability to maintain its original form under a high temperature and high pressure.
According to the extruder screw design, the extruder screw will finish the work of cutting and plastification mainly by the screw edge during the rotation and pushing the plastic forward. Therefore, the screw edge will bear a huge shear stress and friction. Because the extruder rod should be working under such harsh conditions for a long time, the screw edge is worn, and becomes smaller, and the gap of the material barrel increased which leads to the decrease of plastic extrusion quantity, even more seriously cause the backflow of plastics. The decrease of plastification, the crystal particle will appear and the production will fall.
The extruder screw design made by cold rolling process improves the degree of finish of the surface and antifatigue life of the product. After the cold rolling process, the stability of the required tolerance size is greatly improved which can reduce the deformation effects of the spline to ensure that the core shaft and elements are in full agreement. After cold rolling process, the spline forms compressibility stress. Under compression,the materials are not easy to crack, whereas the material under tension will stretch and eventually break.