Plastic extrusion die is a kind of die for producing plastic profile products with continuous shape. It is also called extrusion die, extrusion head or die head.
The word extrude consists of Latin "ex" (leave) and "trudere" (push), which vividly describes the extruding process of "applying pressure to drive materials through the mold".
In the processing, the powdery or granular polymer is usually added to the extruder barrel. Under the action of the screw or plunger, the polymer moves forward along the screw groove or barrel, and gradually melts into the viscous fluid. Then through the mold set at the end of the barrel, a continuum similar to the die shape is formed. Finally, after cooling and setting, the polymer can be formed into the desired shape Shape products, such as all kinds of plastic tube bar, sheet, plastic steel doors and windows, film, decorative skirting, etc.
The main chemical composition of plastic extrusion profile is PVC, so it is also called PVC profile. It is a new type of building material widely used in recent years. It has excellent properties, convenient processing, and wide use. Because of its physical properties such as rigidity, elasticity, corrosion resistance and excellent aging resistance, it is usually used as a good substitute for non-ferrous metals such as copper, zinc and aluminum.
It is mainly used for pushing and pulling, opening doors and windows, guardrails, pipes and ceiling materials.
The bending deformation of PVC profile plastic products is a common problem in the extrusion process. The main causes are: uneven discharge of the die; insufficient cooling of the material during the cooling and finalization, inconsistent shrinkage; equipment and other factors.
It is suggested to solve the problem from the following aspects:
1. to ensure the concentricity and levelness of the whole extruder, the concentricity and levelness of the extruder, die, setting die, water tank, etc. shall be corrected each time the die is replaced.
2. assemble the die carefully before start-up to make the clearance of all parts consistent. If the die is found to be unevenly discharged during start-up, the die temperature can be adjusted accordingly according to the bending deformation direction of the blank to ensure that the die is evenly discharged. If the die temperature is invalid, the plasticization degree of the material can be increased appropriately.
3. adjust the cooling system of the setting die to increase the cooling water volume on the side of the profile bearing the tensile stress.
4. adopt the method of mechanical deviation center adjustment, i.e. adjust the positioning bolt in the middle of the setting die while producing, and conduct reverse micro-adjustment according to the bending direction of the profile (be careful when using this method, and the adjustment amount should not be too large).
5. pay close attention to the working quality of the mold, pay attention to the maintenance of the mold, and maintain the mold at any time according to the actual situation. Reduce the bending deformation of PVC profile plastic products.