Screw injection molding machine is an important component, its role is to convey plastics, melting, compacting, stirring and pressure. All of these are in the rotating barrel by the screw to complete, we can see the screw in the plastic machinery is important.
When the screw rotates, the plastic for the inner wall of the cylinder, the bottom surface of SCREW, screw propulsion edge between surfaces and plastics and plastics will produce friction and mutual movement. Plastic is the result of forward movement of this combination, and heat generated by friction is also absorbed and used to increase the temperature of the molten plastic plastic. Screw structure will directly affect the extent to which these effects.
Meanwhile, the rotation of the screw so that the solid bed and melt film between the cylinder inner wall shear effect, so that the melt film and the solid bed of solid interface between the melt. With the solid bed of spiral goes forward, the volume of the solid bed is gradually reduced, while gradually increasing the volume of the bath.
If the solid bed thickness decreases slower than the speed of shallow groove depth, the solid bed may be partially or completely blocked grooves make plastics fluctuate, or due to local pressure due to a variety of plastic melting rate, the melt viscosity, melt temperature range, the viscosity sensitive to temperature and shear rate, pyrolysis gas is corrosive, the difference in coefficient of friction between plastic particles large, ordinary common screw the usual sense of the melt in the processing of certain characteristics of the more prominent there will be a period of excessive shear heating phenomenon of plastic, this phenomenon - as can be eliminated by reducing the screw speed, but this is bound to affect productivity. |
