1. Composition of injection components

The working principle is that during pre molding, the screw in the plasticizing component is driven by a hydraulic motor to rotate the main shaft. One end of the main shaft is connected to the screw key, and the other end is connected to the hydraulic motor key. When the screw rotates, the material is plasticized and the plasticized molten material is pushed into the storage chamber at the front end of the material cylinder. At the same time, the screw retreats under the reaction of the material, and the thrust seat retreats through the thrust bearing. The piston rod is pulled back in a straight line by the nut to complete the measurement. During injection, the oil in the rod chamber of the injection cylinder pushes the piston rod through the bearing to complete the action, and the oil in the rod chamber of the piston pushes the piston rod and screw to complete the injection action.

2. Plasticized components

There are two types of plasticizing components: plunger type and screw type. Below, we will introduce the screw type.

Screw type plasticizing components are mainly composed of screws, barrels, nozzles, etc. During the continuous propulsion process of the rotating screw, the plastic undergoes a physical state change and is finally injected into the mold cavity in a molten state. Therefore, plasticizing components are the core components for achieving uniform plasticization and quantitative injection.

The working principle of screw type plasticizing components: During pre plasticization, the screw rotates, continuously pushing the material falling from the material port into the screw groove forward. The heating ring transfers heat to the material in the screw groove through the material cylinder wall. The solid material is subjected to the dual effects of external heating and screw rotation shear, and passes through the thermal process of each functional section of the screw to achieve plasticization and melting. The molten material pushes open the check ring, flows into the front end of the screw through the surrounding channel of the screw head, and generates back pressure, pushing the screw backward to complete the measurement of molten material. During injection, the screw acts as a plunger, and under the action of the oil cylinder, it quickly moves forward, injecting the molten material in the storage chamber into the mold through the nozzle.

Screw type plasticizing components generally have the following characteristics:

① The screw has two functions: plasticization and injection;

② The screw is only used for pre plasticization during plasticization;

③ The thermal process of plastic during plasticization is longer than that of extrusion;

④ The screw undergoes axial displacement during plasticization and injection, and at the same time, the screw is in an intermittent working state of rotating and stopping, thus forming the instability of the screw plasticization process.