1. Insufficient cooling. Due to the insufficient cooling of each part of the pipe, the cooling rate of each part is inconsistent, and some parts are generated after setting, which causes the surface of the product to be uneven. Countermeasures: dredge waterways, increase water holes, and increase flow. 2. The vacuum degree is not enough. The geometry and dimensional accuracy of the plastic pipes are controlled by the shaping die. After the pipe leaves the die head, the deformation is quite serious under the action of its own weight. After entering the shaping die, it can fit into the cavity of the shaping model under the action of vacuum adsorption force. If the vacuum degree is not enough, the material does not fit perfectly with the cavity, which will cause the surface of the pipe to be uneven. Countermeasures: Check the tightness, clear the air passage, and improve the vacuum degree. 3. The traction speed is too fast. Too fast traction speed is inconsistent with the extrusion speed, the parison stretching ratio is too large, and the surface is uneven after cooling. Countermeasure: Adjust the traction speed appropriately.
