Injection molding machine classification

(1) Classification of plasticizing methods

① Plunger injection molding machine

The characteristic is that the plasticizing parts are the barrel and the plunger, the plastic entering the barrel is heated by the barrel, and the injection molding process is propelled by the plunger. However, due to the lack of mixing of the melt in the barrel, the temperature difference between the melts is very large, and the temperature distribution of the melt is uneven.

② Screw plunger injection molding machine

The plasticizing device of this injection molding machine is separated from the injection device. The parts that plasticize the rubber are the screw and the barrel, while the injection part is completed by the plunger. The rubber is first uniformly plasticized by the screw in the plasticizing barrel, then enters the injection barrel through the one-way valve, and finally is pushed into the mold cavity by the plunger.

③ Reciprocating screw injection molding machine

The parts of this injection molding machine that plasticize the plastic are the screw and the barrel. The rubber entering the barrel is not only heated by the barrel, but also softened by the shear heat and frictional heat generated when the screw rotates. . The injection process is completed by the screw. During the plasticizing process, due to the rotation of the screw, the plastic melt has axial movement, lateral flow and circular motion. These different forms of movement greatly promote the mixing effect of the plastic melt and make the temperature inside the melt achieve high uniformity. Moreover, the screw moves back and measures while rotating and plasticizing, so its plasticizing capacity is large and the plasticizing quality is good. Therefore, reciprocating screw injection molding machines are widely used.

(2) Classified by clamping device

① Fully mechanical

The mechanical mold clamping device means that the movement of the mechanism to the generation and maintenance of the clamping force is completed by mechanical transmission, also known as the fully mechanical mold clamping device. The early injection molding machines were all mechanical mold clamping devices, but due to the complicated adjustment of mold clamping force and mold clamping speed, inertial impact and noise, and difficult maintenance, few manufacturers currently produce them.

② Fully hydraulic

The hydraulic mold clamping device means that the mold clamping action to the generation and maintenance of the clamping force are all realized by the hydraulic transmission system. The hydraulic mold clamping device is safe and reliable, with low noise, and can easily adjust the mold clamping speed and clamping force. However, there are disadvantages such as hydraulic oil leakage, pressure fluctuations and weak system rigidity.

③ Hydraulic-mechanical

The hydraulic-mechanical mold clamping device is composed of a hydraulic system and a mechanical toggle system, and has the advantages and disadvantages of both the mechanical and hydraulic mold clamping devices. It is currently the most commonly used type of thermoplastic injection molding machine.

④ Electro-mechanical

The electric-mechanical mold clamping device is composed of a servo motor, a winding toothed belt, a screw rod, and a toggle mechanism. This mold clamping device has no hydraulic pressure, which can avoid the problem of oil leakage, and has the advantages of energy saving, low noise, cleanliness, and convenient operation and maintenance. At present, most of the dust-free workshops use this type of clamping device.

(3) Classified by arrangement

① Horizontal injection molding machine

This is the most common type. The mold clamping part and the injection part are on the same horizontal center line, and the mold is opened along the horizontal direction. Its characteristics are: short body, easy to operate and maintain; low center of gravity of the machine, relatively stable installation; after the product is ejected, it can automatically fall by gravity, which is easy to realize fully automatic operation. At present, most injection molding machines on the market use this type.

② Vertical injection molding machine:

The clamping 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, it is easy to place inserts, it is more convenient to load and unload molds, and the materials falling from the hopper can be more evenly plasticized. However, after the product is ejected, it is not easy to automatically fall, and it must be taken off by hand, which is difficult to realize automatic operation. Vertical injection molding machines are suitable for small injection molding machines. Generally, injection molding machines below 60 grams are used more, and large and medium-sized machines are not suitable for use.

③ Angle injection molding machine:

The injection direction and the interface of the mold are on the same surface, which is especially suitable for planar products that do not allow gate traces to be left on the machining center. It occupies a smaller area than a horizontal injection molding machine, but inserts placed in the mold are prone to tilting and falling. This type of injection molding machine is suitable for small machines.

④ Multi-mode Rotary Injection Molding Machine:

It is a special injection molding machine with multi-station operation. Its characteristic is that the mold clamping device adopts a turntable structure, and the mold rotates around the shaft. This type of injection molding machine gives full play to the plasticizing ability of the injection device, which can shorten the production cycle and increase the production capacity of the machine, so it is especially suitable for large-volume products that have a long cooling and setting time or require more auxiliary time due to the placement of inserts. production. However, due to the large and complex mold clamping system, the mold clamping force of the mold clamping device is often small, so this kind of injection molding machine is widely used in the production of plastic shoe soles and other products.