Equipment: extruder, head, shaping device, cooling tank, haul-off equipment and cutting equipment
1. Molding
It is realized by extrusion die. The melt passes through the screen and filter plate, diversion zone, compression zone, molding zone and becomes a tube.
2, shaping
Methods: ID sizing and OD sizing (internal pressure method and vacuum method)
3, pipe extrusion process conditions control
Temperature: barrel, head and mouth mold temperature, is the main factor affecting plasticization and product quality. Extruded pipe temperature is generally low, high viscosity, conducive to shaping.
Extrusion rate: affect the output and quality, its value is determined by the screw speed
Traction speed: affect the pipe wall thickness and diameter of the accuracy, to be compatible with the extrusion speed.
Compressed air pressure: internal pressure method pressure 0.02 ~ 0.05MPa 1, extrusion and blowing
Equipment: extruder and head, cooling device, plywood, haul-off rollers, guide rollers, winding device.
2, blown film extrusion process conditions
Temperature: barrel, head and neck temperature. Temperature is too high, the film is brittle, tensile strength decreased; too high, low tensile strength, poor surface gloss, decreased transparency, there are fusion marks.
Blow-up ratio and draw ratio: blow-up ratio - tube film diameter to mouth mold ratio (2-3); draw ratio - film elongation times (4-6).
Cooling speed: regulated by the cooling device. Freezing line - blown tube on the film has been cooled and shaped line; freezing line the farther, the slower the cooling rate, the film is easy to tear transversely.