How to Effectively Control the Temperature of Injection Molding Machine Barrel?

About the temperature control of the injection molding machine barrel

The temperature control of the injection molding machine barrel is to use the microcomputer control circuit to select the appropriate control algorithm to complete the control of the heating sleeves outside the injection machine barrel. Ensure that the working temperature of each section in the barrel can be kept within the set range according to the technical requirements.

Accurate temperature control is a very important indicator for improving product quality and raw material utilization in precision injection molding.

temperature of injection molding machine barrel

The barrel temperature control object of the injection molding machine is a nonlinear, uncertain, strongly coupled and large lagging system, which is one of the control difficulties.

For this kind of objects, there is still a lack of a unified and effective control method, and the conventional PID control method cannot meet the requirements of high-precision injection.

Adaptive temperature control strategy

When in the following situations, then the parameters of the barrel temperature object model are different:

  • Products produced by the injection molding machine are different.
  • The amount of pre-plastic is different.
  • The ambient temperature is different.
  • The production cycle is different.

There is a strong coupling phenomenon between the temperature control of each section of the barrel. And it is very difficult to achieve complete decoupling control.

In addition, the object is also a large hysteresis system, and conventional control methods will inevitably lead to large overshoot and oscillation.

Therefore, an adaptive temperature control strategy must be studied to achieve high-precision temperature control.

In the process of plastic processing, temperature control mainly includes the temperature control of barrel, nozzle and mold.

The barrel temperature is the heating temperature of the barrel surface. Since 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, two-point parallel detection, that is, setting thermocouples on the surface and depth of the barrel at the same time, will obtain a relatively stable temperature curve, which is conducive to the accuracy of temperature control.

The temperature of the nozzle directly affects the shear flow when the melt passes through, and has a great influence on the quality of the product. Thus, the control accuracy of the nozzle temperature is required to be higher.

Mold temperature refers to the temperature of the cavity surface in contact with the product, which can significantly affect the filling, cooling and packing processes.

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