What are the factors affecting the molding of the plastic extruder? – Suzhou Polytime Machinery Co., Ltd.

The main parameters affecting the extrusion process of the plastic extruder are temperature, pressure, and extrusion rate. Temperature is an important condition for the smooth extrusion process. When the material is plasticized in the barrel, its temperature shall not be lower than its viscous flow temperature, otherwise, the extrusion process will be affected, the quality is difficult to guarantee, and the temperature shall not be too high. The too high temperature will cause the decomposition reaction of the plastic, resulting in the destruction of the plastic structure and can not be used. Therefore, in general, the extrusion temperature should choose an appropriate value between viscous flow temperature and decomposition temperature.

Here is the content list:

What are the characteristics of temperature control of plastic extruder?

What are the process requirements of plastic extruder?

What are the characteristics of temperature control of plastic extruder?
As one of the important controlled variables in the process control system, the temperature characteristics of the controlled object show some similarities. First of all, the stable working conditions of the object are reflected in the balance between the inflow and outflow of heat inside the object. If the process requires that the temperature value be maintained at the set value, the system must control the inflow and outflow of heat at any time, that is, heating and cooling. Secondly, due to the large storage capacity of the controlled object, the temperature changes very slowly and the time scale is long, usually a few minutes or even tens of minutes. Third, most systems have the phenomenon of transmission delay, resulting in a pure delay in the temperature characteristics of the controlled object.

In addition to the characteristics of general temperature control, extruder machine temperature control also has its particularity, which is mainly reflected in the following aspects.

1. The time constant is large, and the pure delay is very long.

2. Tight coupling between temperature control areas.

3. Strong interference.

Due to the influence of the above factors, the plastic extruder temperature system has the characteristics of large time scale, high nonlinearity, and strong dynamic mutation, which makes the control complex.

What are the process requirements of plastic extruder?
The temperature requirement of the extrusion process is the performance index of the temperature control system. These indexes are concentrated on the stability, accuracy, and rapidity of the system. According to the difference of operation process state, it is divided into two categories: static index and static index, including the following aspects.

1. Temperature control accuracy

Temperature control accuracy is the primary standard of extruder temperature control. It is reflected in the difference between the actual temperature value and the set value when the extruder is in a normal extrusion state. The smaller the difference is, the higher the accuracy is. The deviation can be regarded as the steady-state deviation of the system, and this index reflects the accuracy of the control system.

2. Heating time

Temperature rise time is one of the dynamic indexes of the system, which shows the rapidity of the system. The heating time is mainly the requirement for the preheating of the extruder. In the preheating stage of the extruder, the temperature of the inner wall of the barrel needs to be increased from room temperature to the predetermined temperature. Due to the large deviation, the heating time may be too long.

3. Maximum temperature overshoot

To reduce the regulation time of the system, it is often necessary to increase the heat output of the heating device, which may cause serious overshoot and overshoot oscillation of the system. Therefore, the extruder machine temperature control system should try to avoid large overshoot, and even sacrifice some adjustment time when necessary, to ensure that the system does not have large oscillation.

Temperature plays a decisive role in plastic extrusion and is an important aspect of the extrusion process. Therefore, it is very necessary to control the working temperature of plastic extruders within the reasonable range of process. Suzhou Polytime Machinery Co., Ltd. is committed to improving the quality of human life. Through continuous efforts in technology development and product quality control, it has become a first-class international enterprise. If you are engaged in plastic extruder-related work, you can consider our cost-effective products.