1. Controlled by Microcomputer
The temperature of injection molding machine barrel is controlled by the microcomputer control loop. Select the appropriate algorithm to control the heating band outside the barrel of the injection machine. Ensure that the working temperature of each section of the barrel can be kept within the set range according to the technical requirements. For precise plastic injection molding, accurate temperature control is beneficial to improve the quality of the product and the utilization rate of raw materials. It is a very important indicator.
2. Controlling Object
The temperature control of the barrel is a nonlinear, uncertain, strong coupling and large lag system. In fact, it’s one of the control difficulties. For such objects, there is currently no uniform and effective control method. At the same time, the conventional PID control method cannot meet the requirements of high precision injection.
3. Temperature Control Strategies
The injection molding machine producing different products, with different pre-plasticization, ambient temperature and production cycle, the parameters of the barrel temperature will be different. There is a strong coupling phenomenon between the temperature control of each section. So it’s very difficult to achieve complete decoupling control. In addition, the object is still a large lag system, and conventional control methods will inevitably have large overshoot and oscillating phenomena. Therefore, it is necessary to study adaptive temperature control strategies to achieve high-precision temperature control.
4. Selection of the Detection Point of Thermocouple
In plastic processing, temperature control mainly includes temperature control of the barrel, nozzle and mold. The barrel temperature is the heating temperature of the barrel surface. Because the wall of the barrel is relatively thick, the selection of the thermocouple detection point is very critical. And the temperature curves at different detection points are quite different. Therefore, the two-point parallel detection. That is, the simultaneous setting of the thermocouple on the surface and the depth of the cylinder, will obtain a relatively stable temperature curve, which is favorable for the accuracy of temperature control.