Dual Vacuum Cover Vacuum Compression Molding Machine 250 Ton 3RT Automotive Rubber Bellow Molding Machine

Dual Vacuum Cover 250 Ton 3RT Automotive Rubber Bellow Molding Machine Vacuum Compression

Rubber Injection Molding Machine Development Trendency:

The concept of rubber injection machines was proposed in the mid-1940s; in the early 1970s, rubber cold feed injections began to be practically used in industry. Because it can realize high temperature and rapid vulcanization, preheating and plasticizing before the rubber enters the cavity, the product is vulcanized in the sealed high pressure cavity, the product quality is uniform and stable, the size is accurate, and the automatic operation can be realized, and the traditional molding Compared with the production efficiency, the method can increase the production efficiency by more than ten times, so the technology for producing molded articles by the rubber cold feed injection machine is increasingly widely used.

Rubber injection molding machine is mainly used in the production of auto parts, industrial parts, electrical insulation parts, connector sockets, seals, cushions, shockproof covers, shoes, corks, vacuum hoses, sheaths, valve pads, toys And fitness equipment, etc. With the development of the automotive industry, the quality requirements for seals, electrical connectors, shock absorbers, etc. are getting higher and higher, and the demand for rubber injection only increases by more than 12,000 times. The strong market demand is the development of rubber injection machines. Provided an opportunity.
At present, the main manufacturers of rubber injection machines in the world are: French REP company, Austria MAPLAN company, Germany WP company, STEINL company and DESMA, Japan Matsuda Manufacturing Co., Kobe Machinery Co., Ltd., Sanyou Co., Ltd., Nippon Steel Works , Italy RUTIL company.

In the early 1970s, Beijing University of Chemical Technology cooperated with a factory in Shanghai to develop a successful XZL-200 screw pre-plasticized one-line rubber injection molding vulcanizer. China has introduced rubber injection machines from Europe, the United States and Japan. On this basis, domestic manufacturers, such as Huatai, Huacheng, and Huali (now known as Qianpu), have begun to develop and produce rubber injection machines.

1. Rubber injection molding machine structure

There are many types of rubber injection molding machines. So far, rubber injection molding has gone through three stages: plunger injection, screw reciprocating injection and screw-plunger injection.

Plunger injection molding machine

The earliest rubber injection molding uses a plunger injection molding machine. The injection molding method is: after the rubber material is fed into the cylinder from the feeding port, the rubber material is heated and plasticized by the heater outside the cylinder. The compound reaches a temperature that is easy to inject without scorching. Finally, the plasticized compound is injected into the mold by a plunger. In fact, this injection method cartridge is mainly used for injection, supplemented by heat plasticization. Since the rubber is a poor conductor of heat, the heat transfer efficiency is low. If the rubber is heated only by heat conduction, the temperature of the rubber compound rises too slowly, and the plasticization is uneven. Therefore, the rubber material needs to be first heated in a hot-smelting machine, and then heated to a certain extent and then fed into the injection machine. Therefore, although the injection molding method has a simple structure and low cost, the injection machine needs to be equipped with a heat mixer and a rubber mixing worker, thereby increasing the equipment cost and the labor intensity of the worker. The most important thing is that the injection molding method has low production efficiency. The plasticization is uneven, which affects the quality of the product.

2. Screw injection molding machine

In order to improve product efficiency and product quality, another rubber injection molding equipment was invented. That is, on the basis of the extruder, the pure rotation of the screw is changed to be both rotated to plasticize the rubber, and axial movement can be performed to inject the rubber into the cavity. This is a reciprocating screw injection molding machine.

The injection molding method is: after the rubber material enters the injection machine from the feeding port, it is strongly sheared under the rotation of the screw, and the glue temperature is quickly increased. When the compound moves along the screw to the front end of the screw, sufficient and uniform plasticization has been obtained. The screw moves backward while rotating. When the rubber accumulated at the front end of the screw reaches the required injection amount, the axial power mechanism pushes the screw forward with a strong thrust, thereby injecting the rubber into the cavity. In this reciprocating injection molding method, the plasticization of the rubber is obtained by mechanical shearing, so that the rubber material is heated up quickly and the plasticization is uniform, so that the production efficiency and the product quality are improved. In addition, since the injection molding method can directly feed the cold rubber into the injection machine, the thermal refining process is omitted, the equipment investment and the equipment footprint are reduced, the production efficiency is improved, and the labor intensity is reduced. However, in the production of large-scale products, the amount of backward movement of the screw is too large, and the plasticization of the rubber material is limited. In addition, the gap between the screw ridge of the machine and the inner wall of the barrel is large, and the reverse flow and leakage phenomenon are easily caused during the injection. As a result, some of the rubber materials are repeatedly covered, which is prone to scorch, and the injection pressure is also limited. Therefore, the reciprocating screw injection machine can only be used in the production of low-viscosity rubber compounds and small-volume products. Screw-plunger injection molding machine

In order to solve the shortcomings of the above two injection machines, people combine these two injection machines to take advantage of the length and complement each other. This is the screw-plunger injection molding machine that is currently used more. The injection part of the machine is mainly composed of a screw plasticizing system and a plunger injection system. The injection molding process is as follows: first, the cold rubber material is fed into the screw plasticizing system, and the rubber material is plasticized by the screw and squeezed into the plunger. In the injection system, the glue is finally injected into the mold cavity by the plunger. In order to make the rubber flow in a certain order, a check valve is installed at the end of the screw extruder, and the plastic material is plasticized and then enters the injection system through the check valve and pushes the plunger up. Going out of the nozzle, because the nozzle passage is narrow, the resistance is large. When the plunger injects the compound from the nozzle into the mold cavity at a high pressure, the rubber does not flow back into the injection machine due to the action of the check valve. Since this injection molding method combines the advantages of a plunger type injection machine and a screw type injection machine, it can produce large-sized, high-quality rubber products.
Plasticizing system and injection system installation method, sometimes there may be some defects, because the rubber injected into the injection chamber is finally injected into the cavity, which may cause the rubber to stay in contact with the end face of the plunger to stay too long. Vulcanization, resulting in problems such as waste. Large devices are more prone to this situation. A first-in, first-out injection machine can solve this problem.

Although the FIFO injection machine is divided into two parts: screw plasticizing and plunger injection, the two parts are installed in a straight line. At the beginning of the work, the plunger is in the front position, when the plasticized rubber is from the screw. At the front end, after entering the injection chamber through the plunger, the plunger begins to retreat under the action of the rubber pressure until the injection chamber is filled with the required injection amount, and the plunger stops moving backward. Then, the power part drives the plunger to move forward, and performs high pressure injection. In addition, when the rubber material passes through a spherical splitting shuttle before entering the mold, it is further plasticized, and the temperature of the rubber compound is more uniform.

 
Vacuum Compression Machine Parameters:

 
 
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