The working principle of the injection molding machine; in the operation of the injection molding machine, when the screw rotates, the plastic will generate friction and mutual movement between the inner wall of the barrel, the bottom surface of the screw groove, the screw edge advancement surface, and the plastic and the plastic. The advancement of plastic is the result of this combination of movements, and the heat generated by friction is also absorbed to increase the temperature of the plastic and melt the plastic.

The design structure of the screw will directly affect the extent of these effects. At the same time, the rotation of the screw causes the melt film between the solid bed and the inner wall of the barrel to produce a shearing effect, thereby melting the solid at the interface between the melt film and the solid bed. As the spiral of the solid bed moves forward, the volume of the solid bed gradually decreases, while the volume of the molten pool gradually increases.

If the thickness of the solid bed decreases lower than the speed at which the depth of the screw groove becomes shallow, the solid bed may partially or completely block the screw groove, causing fluctuations in plasticization, or due to local pressure due to the melting speed of various plastics, the melt Viscosity, melting temperature range, sensitivity of viscosity to temperature and shear rate, corrosiveness of pyrolysis gas, and friction coefficient between plastic particles vary greatly.

The molding process of a general screw injection molding machine is as follows: first add granular or powdered plastic into the barrel, and make the plastic into a molten state through the rotation of the screw and heating of the outer wall of the barrel, and then the machine closes the mold and moves the injection seat forward. Then pass pressure oil to the injection cylinder.

The screw is pushed forward to inject the melt into a closed mold with a lower temperature at a high pressure and a faster speed. After a certain period of time and pressure maintenance (also called pressure retention) and cooling, it is solidified and formed. Can open the mold to take out the product.

The basic requirements of injection molding are plasticization, injection and molding. Plasticization is a prerequisite for realizing and ensuring the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed. At the same time, due to the high injection pressure, a correspondingly high pressure is generated in the cavity, so there must be a large enough clamping force.