Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment for making thermoplastic or thermosetting materials into various shapes of plastic products using plastic molding molds. According to the arrangement of the injection device and the clamping device, the injection molding machine can be divided into vertical, horizontal and vertical-horizontal composite.
The injection molding machine is the most used processing machine in the plastics processing industry. Not only a large number of products can be directly produced by the injection molding machine, but also the key equipment that constitutes the injection stretch blowing process. China has become the world's largest country in the production of plastic machine parts. The reasons for promoting the development of China's injection molding machine equipment manufacturing industry are: first, joint ventures and technical cooperation with internationally renowned companies; second, Chinese companies have gradually adapted to the international market for mechanical parts The purchase method has mastered the purchase channel. At the same time, the production of injection molding machines in my country also shows strong regional characteristics. Ningbo in Zhejiang and Dongguan in Guangdong have become important injection molding machine production bases in my country and even the world.
The working principle of the injection molding machine is similar to the syringe used for injection. It uses the thrust of the screw (or plunger) to plasticize the molten state
The process of injecting the plastic of the vertical injection molding machine (that is, the viscous fluid state) into the closed mold cavity, and obtaining the product after curing and shaping.
Injection molding is a cyclic process, each cycle mainly includes: quantitative feeding-melting plasticization-pressure injection-mold filling and cooling-mold opening and taking parts. After taking out the plastic part, the mold is closed 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. The selection of injection process action, feeding action, injection pressure, injection speed, ejection type, temperature monitoring of each section of the barrel, and adjustment of injection pressure and back pressure are performed respectively.
The molding process of a general screw injection molding machine is as follows: first add granular or powdered plastic into the barrel, and turn the screw and heat the outer wall of the barrel to make the plastic into a molten state, and then the machine closes the mold and moves the injection seat forward. Make the nozzle close to the gate of the mold, and then pass pressure oil into the injection cylinder to push the screw forward, thereby injecting the melt into the closed mold with a lower temperature at a high pressure and a faster speed. Time and pressure hold (also known as holding pressure) and cooling to make it solidify and form, then the mold can be opened and the product can be taken out (the purpose of holding pressure is to prevent the reflux of the melt in the mold cavity, replenish materials into the mold cavity, and protect
General horizontal injection molding machine
Certified products have certain density and dimensional tolerances). The basic requirements of injection molding are plasticization, injection and molding. Plasticization is the prerequisite for realizing and ensuring the quality of molded products, and 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 correspondingly high pressure is generated in the cavity (the average pressure in the cavity is generally between 20 and 45 MPa), so there must be a sufficient clamping force. It can be seen that the injection device and the clamping device are the key components of the injection molding machine.
There are three main aspects to the evaluation of plastic products. The first is the appearance quality, including completeness, color, gloss, etc.; the second is the accuracy of the size and relative position; the third is the physical properties, chemical properties, and Electrical performance, etc. These quality requirements are different depending on the use occasion of the product, and the required scale is also different. The defects of the product mainly lie in the design, manufacturing accuracy and degree of wear of the mold. But in fact, the technicians of plastic processing plants often suffer from the difficult situation of using technological means to compensate for the problems caused by mold defects without great results.
The adjustment of the process in the production process is a necessary way to improve the quality and output of products. Because the injection cycle itself is very short, if the process conditions are not well mastered, there will be an endless stream of waste. When adjusting the process, it is best to change only one condition at a time and observe a few more times. If the pressure, temperature, and time are all adjusted together, it is easy to cause confusion and misunderstanding. If there is a problem, I don't know the reason. The measures and means to adjust the process are various. For example, there are more than a dozen possible ways to solve the problem of product dissatisfaction, and only one or two main solutions to solve the problem can be truly solved. In addition, attention should be paid to the dialectical relationship in the solution. For example, if the product has a depression, sometimes the material temperature must be increased, sometimes the material temperature must be lowered; sometimes the material quantity must be increased, and sometimes the material quantity must be reduced. It is necessary to recognize the feasibility of reversing measures to solve the problem.
