(1) SJ65-B is selected for the extruder, the straight-through type is selected for the machine head, and the compression of the machine head is larger to 2.5:1; The aspect ratio is: L/D value is 25:1; The screw groove of the screw is equally spaced and unequal in depth.
The melt viscosity of recycled soft PVC is low and the fluidity is very good, so that the compression ratio of the head is controlled at 10~20, the length of the straight part of the mouth film is about 10~20 times the wall thickness of the hose, and the size of the core film can be expanded by 10%~20% compared with the inner and outer diameter of the tube. After extruding the PVC hose, it needs to be stretched to reach the required pipe diameter size, and the cooling method adopts spray cooling water cooling, and the spray position is 20~40mm away from the machine head.
(2) Temperature control range of each section of the extruder when extruding PVC hose:
Feeding section: 100°C-120°C; Compression section: 120°C-140°C; Homogenization measurement section: 140°C-160°C; Shunt: 140°C-160°C; Mouth film: 160°C-180°C.
(3) Selection of screw speed:
Because the melting fluidity of recycled soft PVC is good and easy to plasticize, the screw speed is faster than that of hard PVC, and the screw speed of the extruder with a general screw diameter of 65mm is (30±10)r/min. Because the ventilation hole is connected to the outside air, no compressed air is required during processing, and there is no adhesion and unrounded pipe diameter.
(4) Control of traction speed
When the recycled PVC hose is produced, there is no need to pass compressed air into the pipe, nor does it need to cool and shape, so that the traction force is reduced accordingly, and the traction speed must be strictly controlled to ensure the wall thickness of the pipe and the outer diameter size of the recycled PVC hose.
