The working principle of the injection molding machine is similar to that of the syringe for injection. It is to inject the plasticized molten state (ie, the viscous flow state) into the closed cavity by the thrust of the screw (or plunger). The process of obtaining the product after curing and setting.
Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding - melt plasticizing - pressure injection - filling mold cooling - mold extraction. After removing the plastic part, the mold is closed again and the next cycle is performed.
Injection molding machine operation items: Injection molding machine operation items include three aspects: control keyboard operation, electrical control system operation and hydraulic system operation. The injection process, the feeding action, the injection pressure, the injection speed, the selection of the ejection type, the monitoring of the temperature of each section of the barrel, the adjustment of the injection pressure and the back pressure are performed.
Generally, the molding process of the screw type injection molding machine is: firstly, the granular or powdered plastic is added into the barrel, and the plastic is melted by the rotation of the screw and the outer wall of the barrel, and then the machine performs the mold clamping and the injection seat forward. The nozzle is placed close to the gate of the mold, and then the pressure oil is introduced into the injection cylinder to advance the screw, thereby injecting the melt into the lower temperature closed mold at a high pressure and a relatively high speed. Time and pressure are maintained (also known as holding pressure), cooled, and solidified, and the product can be opened by mold opening (the purpose of holding pressure is to prevent backflow of molten material in the cavity, replenish material into the cavity, and ensure the product Has a certain density and dimensional tolerance).
The basic requirements for injection molding are plasticization, injection and molding. Plasticization is the premise to achieve and ensure the quality of molded products, and in order to meet the molding requirements, 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 a sufficient clamping force must be obtained. It can be seen that the injection device and the clamping device are key components of the injection molding machine.
There are three main aspects for 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 properties and chemical properties corresponding to the application. Electrical properties, etc. These quality requirements are different depending on the use of the product. The defects of the product mainly lie in the design, manufacturing precision and wear degree of the mold. But in fact, the technicians of plastic processing plants often suffer from the difficult situation of using technology to compensate for the problems caused by mold defects.
Process adjustment during production is a necessary way to improve product quality and yield. Since the injection cycle itself is very short, if the process conditions are not well mastered, the waste will continue to flow. 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 unified, it is easy to cause confusion and misunderstanding. If you have problems, you don't know why. The measures and means of adjusting the process are various. For example, there are more than a dozen possible solutions to solve the problem of product dissatisfaction. It is necessary to select one or two major solutions to solve the problem and solve the problem. In addition, attention should be paid to the dialectical relationship in the solution. For example: the product has a depression, sometimes to increase the temperature of the material, sometimes to reduce the temperature of the material; sometimes to increase the amount of material, and sometimes to reduce the amount of material. It is necessary to acknowledge the feasibility of solving the problem of reverse measures.
The energy saving of an injection molding machine can be divided into two parts: one is the power part and the other is the heating part.
Power saving: Most of the inverters are used. The energy saving method is to save the residual energy of the motor. For example, the actual power of the motor is 50 Hz, and you only need 30 Hz in production to produce enough, and the excess energy consumption is vain. Wasted, the inverter is to change the power output of the motor to achieve energy saving.
Energy saving in heating part: Most of the energy saving in heating is energy saving by electromagnetic heater, and the energy saving rate is about 30%-70% of the old resistor ring.
1. Compared with resistance heating, the electromagnetic heater has an additional layer of insulation, and the heat utilization rate is increased.
2. Compared with resistance heating, the electromagnetic heater directly acts on the material tube to reduce the heat transfer heat loss.
3. Compared to resistance heating, the heating rate of the electromagnetic heater is faster than one quarter, which reduces the heating time.
4. Compared with resistance heating, the heating speed of the electromagnetic heater is fast, the production efficiency is improved, and the motor is in a saturated state, which reduces the power loss caused by high power and low demand.
