Working Process of Dual Screw Extruder

1. What is a dual-screw extruder?

dual-screw extruder is an important equipment in plastic processing machinery. It is not only suitable for extrusion molding and mixing processing of polymer materials, but its uses have been expanded to food, feed, electrodes, explosives, building materials, Packaging, pulp, ceramics and other fields. The extruder has high speed and high output, which enables investors to obtain large output and high return with low input.

However, the high speed of the screw speed of the extruder also brings a series of difficulties to be overcome: if the residence time of the material in the screw is reduced, the mixing and plasticization of the material will be uneven, and the material may be subjected to excessive shearing, which may cause the material to heat up rapidly and heat up. Decomposition, the difficulty of extrusion stability control will cause the geometric size of the extrudate to fluctuate, the accuracy of the related auxiliary devices and control systems must be improved, and the wear of the screw and barrel will increase, and high wear-resistant and ultra-high wear-resistant materials, reducers Problems such as how to improve the life of the bearing in the case of high-speed operation need to be solved.

On the whole, the research on the theory of twin screw extruder machine is still in the initial stage, which is the so-called " more skill than science "; the electrical automation control of the working process of the extruder is also constantly developing, and the traditional electrical control is separate It is realized by single-machine automatic instrument, and now it has developed into an electrical control system composed of touch screen, PLC, temperature control module, frequency conversion speed regulation, etc. composed of human-machine interface technology, computer technology, frequency conversion technology, etc.

2. Working process of dual-screw extruder

The setting value in the touch screen is transmitted to the PLC through the communication line, and the current temperature on the barrel and the die is transmitted to the temperature control module for processing through the thermocouple, and then transmitted to the PLC by the temperature control module.

When the temperature value and the set value are compared in the PLC, if the current value is lower than the set value, the PLC will issue an instruction to make the corresponding thermoelectric device in the PLC work and make the contactor work.

Due to the closing of the contactor, the heater is energized and heated. During the heating process, the thermocouple continuously transmits the current temperature to the temperature control module, and the temperature control module also continuously transmits the value to the PLC for numerical comparison. After a period of heating, if the current temperature value is higher than the set value, the PLC will issue an instruction to make the relays and contactors inside the PLC lose power and not work.

Due to the disconnection of the contactor of the double screw extruder, the heater is powered off and does not heat. For those with cooling fans, the PLC simultaneously sends out instructions to make the corresponding relays in the PLC work, so that the fans are energized to work. Cooling by the fan reduces the current temperature of the barrel. When the barrel temperature reaches the set value, the PLC issues an instruction to make the internal relay lose power and not work, and make the intermediate relay coil lose power and stop working. Because the intermediate relay is disconnected, the cooling fan is powered off and stops working.