The working principle of the injection molding machine is similar to that of the syringe for injection. It is the process of injecting the plasticized molten plastic (i.e. viscous flow) into the closed mold cavity with the help of the thrust of the screw (or plunger), and obtaining the product after curing and shaping.
Injection molding is a cycle process, each cycle mainly includes: quantitative feeding – melting and plasticization – pressure injection – mold filling and cooling – mold opening and taking parts. After taking out the plastic part, close the mold again for the next cycle.
Injection molding machine operation items: injection molding machine operation items include control keyboard operation, electrical control system operation and hydraulic system operation. Select the injection process action, feeding action, injection pressure, injection speed and ejection type, monitor the temperature of each section of the barrel, and adjust the injection pressure and back pressure.
The molding process of general screw injection molding machine is: first, add granular or powdery plastic into the barrel, and make the plastic melt through the rotation of the screw and the heating of the outer wall of the barrel, then the machine closes the mold and moves the injection seat forward to make the nozzle close to the gate of the mold, and then inject pressure oil into the injection cylinder to push the screw forward, Thus, the molten material is injected into the closed mold with low temperature at a high pressure and fast speed. After a certain time and pressure maintenance (also known as pressure holding) and cooling, the mold can be opened and the product can be taken out (the purpose of pressure holding is to prevent the reverse flow of molten material in the mold cavity, supplement materials to the mold cavity, and ensure that the product has a certain density and dimensional tolerance). The basic requirements of injection molding are plasticization, injection and molding. Plasticization is the premise to realize and ensure the quality of molded products. 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 high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 ~ 45MPa), so there must be a large enough clamping force. It can be seen that the injection device and clamping device are the key components of the injection molding machine.
Post time: Dec-20-2021