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Injection machine is the main modeling equipment which makes thermoplastic or thermosetting plastics into plastic products of various shapes by using plastic models.
The working principle of the injection machine is similar to that of the syringe used for injection. It is a process of injecting the plasticized melt state (i.e. viscous flow state) into the closed cavity with the help of the thrust of the screw (or plunger) to obtain the product after solidification and shaping.
Injection modeling is a cyclic process, each cycle mainly includes: quantitative feeding - melting plasticization - pressurized injection - filling cooling - opening parts. After removing the plastic parts, the model is closed again for the next cycle.
Injection Molding Machine Operating Items: Injection Molding Machine Operating Items include three aspects: 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, injection pressure and back pressure adjustment are carried out respectively.
Generally, the forming process of screw injection machine is: firstly, granular or powdery plastics are added into the barrel, and the plastics are melted by the rotation of screw and the heating of the outer wall of barrel. Then the machine closes the model and moves the injection seat forward to make the nozzle close to the gate of the model. Then the pressure oil is injected into the injection cylinder to push the screw forward, so that the melt can be injected into the closed die with a lower temperature at a higher pressure and a faster speed. After a certain period of time and pressure to maintain, cooling, so that it solidifies and forms, can open the mold to take out products. The basic requirements of injection modeling are plasticization, injection and modeling. Plasticization is the precondition of realizing and guaranteeing the quality of modeled products. In order to meet the requirements of modeling, injection must ensure sufficient pressure and speed. At the same time, due to the high injection pressure, the corresponding high pressure in the cavity (the average pressure in the cavity is usually between 20 and 45 MPa), so it must have enough clamping force. Therefore, injection device and clamping device are the key parts of injection machine.
There are three main aspects in the evaluation of plastic products. The first is the appearance quality, including integrity, color, gloss, etc. The second is the accuracy between size and relative position. The third is the physical, chemical and electrical properties corresponding to the use. These quality requirements are different according to the different occasions of product use, and the scale of requirements is also different. The defects of products mainly lie in die design, manufacturing accuracy and wear degree. But in fact, the technicians in plastic processing factories often suffer from the difficult situation of making up for the defects of dies by means of technology.
Adjustment of process in production process is a necessary way to improve product quality and output. Because the injection cycle itself is very short, if the process conditions are not well mastered, there will be endless waste products. When adjusting the process, it is best to change only one condition at a time and observe it several times. If the pressure, temperature and time are adjusted in a unified way, it is easy to cause confusion and misunderstanding, and if something goes wrong, we don't know what the reason is. There are many measures and means to adjust the process. In addition, attention should be paid to the dialectical relationship in the solution. It is necessary to recognize the feasibility of solving the problem by adverse measures.
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