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Do you know why the twin-screw extruder barrel is easily damaged?
- 2018-09-14 -

The same-parallel building block type twin-screw extruder barrel This part has an important influence on the plasticization of the twin-screw extruder, the quality of the product and the production power. Their work quality is related to the manufacturing accuracy and installation clearance of the two parts. When the wear of the two parts is severe and the operating power of the extruder is low, the repair of the cylinder should be organized. Because the screw extruder works under high temperature, high pressure, high mechanical torque and high friction environment. The first three conditions are necessary for the operation of the screw extruder, and the latter conflicts cannot be prevented.

The conflict between the material and the two: the screw rotates in the cylinder, and the material conflicts with the two, so that the working appearance of the screw and the cylinder gradually wears out: the diameter of the screw will collide and shrink, and the diameter of the inner hole of the cylinder increases due to conflict. Therefore, the cooperative diameter of the screw and the cylinder will be larger and larger (the screw is subjected to external nitriding during operation to improve the hardness of the surface), because the resistance of the front head and the splitter plate of the cylinder is not changed, which adds The leakage flow when the extruded material travels, that is, the amount of material flowing from the diameter gap to the feed direction. The result is a reduction in extruder production. This results in the addition of material residence time in the barrel, forming a material differentiation. If the material is polyethylene, the hydrogen chloride gas that is differentiated strengthens the corrosion of the cylinder and forms a vicious circle.

The physical properties of the material: If the crusher is found to have fillers such as calcium carbonate and glass fiber, the friction of the material to the metal material is often much greater than that of the molten plastic. In the injection of these plastics, if the high rotational speed is increased along with the shearing force on the plastic, more shredded fibers are correspondingly produced, and the shredded fibers contain a sharp end, which greatly increases the wear force. Therefore, the rotation speed of the extruder should not be adjusted too high.

The plasticization scale of various plastics is different: each plastic has an ideal plasticizing processing temperature scale. The granular plastic enters the barrel from the hopper, first reaches the feeding section, and in the feeding section, dry friction will inevitably occur. When these plastics When the heat is lacking and the melting is uneven, it is easy to form the inner wall of the cylinder and the wear of the screw surface is increased. Similarly, in the tightening section and the homogenization section, if the melting state of the plastic is uneven, the wear is also increased.