Straight-through nozzle is a widely used nozzle, characterized in that the spherical surface of the nozzle is directly in contact with the main pouring spherical surface of the mold. The arc radius and flow path of the nozzle are smaller than the mold. When the injection is performed, the high-pressure melt directly passes through the mold runner system. Filled into the mold cavity, speed, pressure loss, manufacturing and installation are more convenient.
Locking nozzles are mainly used to solve the flow problem of straight-through nozzles and are suitable for the processing of low-viscosity polymers (such as PA). The nozzle flow path can be closed during the pre-molding to prevent the melt from flowing, and when injected, it can be opened under the action of the injection pressure to inject the melt into the cavity.
2. Injection cylinder
The working principle is: when the injection cylinder is oiled, 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 adjusted synchronously by the nut of the piston rod head.
When the thrust seat is injected, the thrust seat pushes the screw through the thrust shaft for injection; while in the pre-plasticizing, the thrust shaft is driven by the oil motor to drive the screw to realize the pre-molding.
3. Block moving cylinder
When the cylinder is moved into the oil, the injection seat can move forward or backward, and the injection nozzle can be in close contact with the main pouring circular surface of the mold to generate an injection seat pressure capable of sealing the melt.
4. Accuracy requirements for injection parts
After the nozzle is assembled, the integral injection part is placed on the frame, and it must be ensured that the nozzle is tightly engaged with the main cast sleeve of the mold to prevent flash.
It is required that the centerline of the injection part should be concentric with the centerline of its part; in order to ensure the 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 guaranteed to be symmetrical with the centerline. degree.
For horizontal machines, the parallelism of the two guide holes of the shift cylinder and the symmetry of its center must also be guaranteed.