Technical requirements for four parts of plastic unit of injection molding machine.
1. The nozzle
The straight-through nozzle is a commonly used nozzle, which is characterized by the nozzle spherical surface directly contacting with the main casting cover of the mold. The circular radius and flow channel of the nozzle are smaller than that of the mold. When injected, the high-pressure melt directly passes through the casting system of the mold to fill the mold cavity, which is faster and has less pressure loss.
The locking nozzle is mainly used to solve the salivation problem of the straight nozzle, and is suitable for the processing of low-viscosity polymers (such as PA). In the preplasticity, the nozzle can be closed to prevent the salivation of the melt, and when injected, it can be opened under the action of injection pressure, so that the melt is injected into the mold cavity.
2. Injection cylinder
The working principle is: when the injection cylinder enters oil, the piston drives the piston rod and its bearing in the thrust seat, and pushes the screw forward or backward. The axial position of the two parallel piston rods and the axial position of the injection screw can be adjusted synchronously through the nut on the head of the piston rod.
When the thrust seat is injected, the thrust seat drives the screw rod through the thrust shaft for injection. When premolding, drive the thrust shaft through the oil motor to drive the rotation of the screw rod to achieve premolding.
3. Oil shifting cylinder
When the oil is moved to the oil cylinder, the forward or backward motion of the injection holder is realized, and the injection nozzle is ensured to be in close contact with the circular arc surface of the main casting sleeve of the mold, so as to generate the injection seat pressure that can seal the melt.

4. Precision requirements for injection parts
After the nozzle is assembled, the whole injection part should be placed on the frame, and the nozzle must be closely connected with the main casting sleeve of the mold to prevent overflow.
It is required to make the center line of the injection part concentric with the center line of the assembly part. In order to ensure the matching accuracy of the injection screw and the inner hole of the feed barrel, the parallelism and symmetry of the center hole of the two injection cylinder holes and the positioning center hole of the feed barrel must be guaranteed.
For horizontal machines, the parallelism of the two guide holes of the seat cylinder and the symmetry of their center must also be guaranteed