Why does PVC profile bend and deform during production?

Bending and deformation

Bending and deformation of PVC profiles is a common problem in the extrusion process. The reasons are: uneven discharge from the die; insufficient cooling of the material during cooling and shaping, and inconsistent shrinkage; equipment and other factors

The concentricity and levelness of the entire extruder line are the prerequisites for solving the bending and deformation of PVC profiles. Therefore, whenever the mold is replaced, the concentricity and levelness of the extruder, die, shaping die, water tank, etc. should be corrected. Among them, ensuring uniform discharge from the die is the key to solving the bending of PVC profiles. The die should be carefully assembled before starting the machine, and the gaps between each part should be consistent. If the die is found to be uneven when starting the machine, the die temperature should be adjusted accordingly according to the bending and deformation direction of the parison. If the adjustment is ineffective, the plasticization degree of the material should be appropriately increased. Auxiliary adjustment Adjusting the vacuum degree and cooling system of the shaping die is a necessary means to solve the deformation of PVC profiles. The amount of cooling water on the side of the profile that bears tensile stress should be increased; the mechanical offset center method is used for adjustment, that is, while producing, the positioning bolts in the middle of the shaping die are adjusted, and the reverse micro-adjustment is made according to the bending direction of the profile (this method should be used with caution, and the adjustment amount should not be too large). Paying attention to the maintenance of the mold is a good preventive measure. The working quality of the mold should be closely monitored and the mold should be maintained and maintained at any time according to the actual situation.

By taking the above measures, the bending deformation of the profile can be eliminated, ensuring that the extruder can stably and normally produce high-quality PVC profiles.

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