The working principle of the plastic injection molding machine is similar to that of the medical syringe for injection. It is a technological process that uses the thrust of the screw (or plunger) to inject the plasticized plastic in the molten state (i.e. viscous flow state) into the closed mold cavity, and obtain products after curing and shaping. Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding - melt plasticization - pressure injection - mold filling and cooling - mold opening and parts taking. Take out the plastic parts and then close the mold for the next cycle.

Classification of plastic injection molding machines:

Plastic injection molding machines can be divided into plunger type plastic injection molding machines and screw type plastic injection molding machines according to the plasticizing mode. They can also be divided into hydraulic type, mechanical type and hydraulic mechanical (connecting rod) type according to the transmission mode of the machine. They can be divided into automatic, semi-automatic and manual plastic injection molding machines according to the operation mode.

1. Horizontal plastic injection molding machine

This is the most common type. In the world, DKM brand plastic injection molding machines are the typical benchmark. For the injection molding machne, the mold closing part and the injection part are on the same horizontal centerline, and the mold is opened in the horizontal direction. Its characteristics are: low body, easy to operate and maintain; The center of gravity of the machine is low and the installation is stable; After the product is ejected, it can fall automatically by gravity, which is easy to realize full automatic operation. Most injection molding machines on the market use this type.

2. Vertical plastic injection molding machine

The mold closing part and the injection part are on the same vertical centerline, and the mold is opened in a vertical direction. Therefore, it occupies a small area, is easy to place inserts, is convenient to load and unload molds, and the materials falling from the hopper can be plasticized more evenly. However, it is not easy for the products to fall down automatically after being ejected, and they must be taken down manually, so it is not easy to realize automatic operation. Vertical injection molding machines should be used for small injection molding machines. Generally, injection molding machines below 60g are used more frequently than large and medium-sized machines.

3. Angle plastic injection molding machine

The injection direction and mold interface are on the same surface, which is especially suitable for plane products where the machining center is not allowed to leave gate traces. It occupies a smaller area than the horizontal injection molding machine, but the inserts placed in the mold are easy to fall down. This type of injection molding machine is suitable for small machines.

4. Multi mold rotary plastic injection molding machine

It is a special injection molding machine with multi station operation. Its feature is that the mold clamping device adopts a turntable structure, and the mold rotates around a rotating shaft. 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. Therefore, it is particularly suitable for the production of large batches of products with long cooling and molding time or requiring more auxiliary time due to the placement of inserts. However, because the clamping system is huge and complex, and the clamping force of the clamping device is often small, this kind of injection molding machine is widely used in the production of plastic soles and other products.

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