What causes the PVC hose to pull out?

Outer diameter of pipe is not round.
(1) the temperature of the melt is rather high, and the temperature of the mould and the barrel should be reduced appropriately.
2. The temperature of the billet extruded from the forming die is not uniform. The cooling method should be adjusted appropriately so that the circumference of the tube blank can be cooled evenly.
3. The deformation of the sizing sleeve is not round. It should be checked and maintained.
In addition, we need to see if the ventilation holes are blocked, and if necessary, use compressed air to blow in.
Some formulations and molds do not match, resulting in various parts of the material is fast and slow, but also easily lead to non circle.