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Technical requirements for four parts of injection molding machine plasticizing unit
- Sep 03, 2018 -

Injection molding machine plasticizing unit four parts technical requirements.

1. nozzle

Straight-through nozzle is a widely used nozzle. Its characteristics are that the spherical surface of the nozzle contacts directly with the spherical surface of the main casting sleeve of the die. The arc radius and runner of the nozzle are smaller than that of the die. During injection, the high-pressure melt is directly filled into the die cavity through the runner system of the die. It has the advantages of high speed, small pressure loss and convenient manufacture and installation.

Locked nozzles are mainly used to solve the salivation problem of straight-through nozzles, which are suitable for the processing of low viscosity polymers (such as PA). The nozzle runner can be closed to prevent molten salivation during pre-molding, and the injection pressure can be used to open the melt injection cavity.

2. injection cylinder

The working principle is: when injecting oil into the cylinder, the piston drives the piston rod and its bearing placed in the thrust seat to push the screw forward or backward. The axial position of the two parallel piston rods and the axial position of the injection screw can be synchronously adjusted by the nut at the head of the piston rod.

When the thrust pedestal is injected, the thrust pedestal pushes the screw through the thrust shaft for injection; while in the pre-molding, the oil motor drives the thrust shaft to drive the screw to rotate to realize the pre-molding.

3. seat shift cylinder

When the seat is moved into the cylinder, the forward or backward motion of the injection seat is realized, and the close contact between the injection nozzle and the arc surface of the main casting sleeve of the mold is ensured, resulting in the injection seat pressure which can seal the melt.

4. precision requirements for injection parts

After the nozzle is assembled, the integral injection parts must be placed on the rack, and the nozzle must be tightly joined to the main casting sleeve of the die to prevent overflow.

It is required that the center line of the injection part should be concentric with the center line of the clamping part; in order to ensure the matching accuracy of the injection screw and the inner hole of the barrel, the parallelism of the two injection cylinder holes and the center hole of the barrel must be ensured and the symmetry of the center line must be ensured.

For horizontal machine, the parallelism of two guide holes and the symmetry of the center must be guaranteed.