The bending deformation of PVC profile is a common problem in the extrusion process. The main reasons are: uneven discharge of the die; insufficient cooling of the material during cooling and shaping, and inconsistent shrinkage; equipment and other factors.
It is recommended to solve from the following aspects:
1. Ensure the concentricity and levelness of the entire extruder line, and correct the concentricity and levelness of the extruder, die, shaping die, water tank, etc. every time the die is changed.
2. Carefully assemble the die before starting the machine to make the gap between injection screw barrel all parts consistent. If the die is found to be unevenly discharged when starting up, adjust the temperature of the die according to the bending and deformation direction of the parison to ensure that the die is evenly discharged, such as adjusting the mouth. The mold temperature is invalid, and the plasticization degree of the material can be appropriately increased.
3. Adjust the cooling system of the shaping die and increase the amount of cooling water on the side of the large material that bears the tensile stress.
4. Use the method of mechanically offsetting the center to adjust, that is, adjust the positioning bolt in the middle of the shaping die while producing, and perform reverse micro-adjustment according to the bending direction of the profile (this method should be used with caution and the adjustment should not be too large).
5. Pay close attention to the work quality of the mold, pay attention to the maintenance of the mold, and maintain and maintain the mold at any time according to the actual situation.