The working principle of the injection molding machine is similar to the syringe used for injection, it is by means of screw (or plunger) thrust, has been plasticized good molten state (that is, viscous flow state) of plastic injection into the closed good mold cavity, after the solidification of the product after the process. Injection molding is a cyclic process, each cycle mainly includes: quantitative feeding -- melt plasticization -- pressure injection -- mold filling and cooling -- mold opening and taking.

Take out the plastic parts and then close the mold again to carry out the next cycle. structure Injection molding machine is divided into plunger type injection molding machine and screw type injection molding machine according to the plasticizing mode, according to the machine's transmission mode can be divided into hydraulic, mechanical and hydraulic - mechanical (connecting rod) type, according to the operation mode is divided into automatic, semi-automatic, manual injection molding machine. 

 (1) horizontal injection molding machine: this is the most common type. The clamping part and the injection part are on the same horizontal center line, and the mold is opened horizontally. Its characteristics are: low fuselage, easy to operate and maintain; Low center of gravity, stable installation; After ejection, the product can fall automatically by gravity, which is easy to realize automatic operation. At present, the injection molding machine on the market mostly adopts this type.   

(2) vertical injection molding machine: the mold closing part and the injection part are on the same vertical center line, and the mold is opened along the vertical direction. Therefore, it occupies a small area, easy to place inserts, easy to load and unload molds, materials falling from the hopper can be plasticized more evenly. However, the products are not easy to fall automatically after ejection, must be taken off by hand, not easy to achieve automatic operation. Vertical injection machine suitable for small injection molding machine, is generally in 60 tons (60 tons is referred to the locking force) below the injection molding machine more, large, medium machine is not suitable to use.   

(3) Angle injection molding machine: the injection direction and the mold interface is on the same surface, it is particularly suitable for the processing center part of the plane products are not allowed to leave gate marks. It takes up less space than a horizontal injection molding machine, but inserts placed into the mold tend to tilt down. This type of injection molding machine is suitable for small machines.   

(4) multi-mode rotary injection molding machine: it is a special multi-station operation of the injection molding machine, its characteristic is that the mold closing device adopts the rotary structure, the mold around the rotating shaft rotation. 

This type of injection molding machine gives full play to the plasticizing capacity of the injection device, which can shorten the production cycle and improve the production capacity of the machine, so it is especially suitable for the production of large quantities of products with long cooling setting time or more auxiliary time due to the installation of inserts. However, due to the huge and complex mold closing system, the mold closing force of the mold closing device is often small, so this injection molding machine in the production of products such as plastic sole more applications.   General injection molding machine includes injection device, mold closing device, hydraulic system, electrical control system, lubrication system, heating and cooling system, safety monitoring system and other parts.  

 The basic requirements for injection molding are plasticization, injection and molding. Plasticizing is the premise to realize and guarantee the quality of the molded products, and to meet the requirements of molding, injection must ensure that there is enough pressure and speed. At the same time, due to the high injection pressure, correspondingly high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 ~ 45MPa), so there must be sufficient clamping force. It can be seen that the injection device and die device are the key parts of the injection molding machine.