Detailed introduction to the control system of three screw granulator

The control system of the three screw granulator includes the heating system, the cooling system and the measurement system of process parameters, which are mainly composed of electrical appliances, instruments and actuators (i.e. control panel and operating table). Its main function is to control and adjust the drag motor of the main auxiliary machine, output the speed and power that meet the requirements of the process, and coordinate the work of the main and auxiliary machines, detect and adjust the temperature, pressure and flow of the plastic in the three screw extruder, and realize the control or automatic control of the whole unit.

The electric control of the extrusion unit is divided into two parts: transmission control and temperature control, which can control the extrusion process including temperature, pressure, screw number, screw cooling, cylinder cooling, product cooling and outer diameter, and the traction speed, neat line and constant tension control from empty disk to full disk. System.

Temperature control of 1. three screw granulation machine

Plastic extrusion of wire and cable insulation and sheath is carried out in the viscous flow state according to the deformation characteristics of thermoplastic. In addition to the external heating of the screw and the cylinder, to the plastic to melt and extrusion, and to consider the heat of the extrusion of the plastic, the temperature of the host should be considered as a whole, considering both the heating and the closing of the heater, and the cooling of the factors of the heat spillover of the screw extruder. Cooling facilities. It is required that the location and installation method of the thermocouple of the measuring element should be correctly and reasonably determined, and the actual temperature of each segment of the main engine can be accurately reflected from the reading of the temperature control instrument. And the accuracy of the temperature control instrument is matched with the system, so that the temperature stability of the whole host temperature control system can meet the requirements of various plastics extrusion temperatures.

Pressure control of 2. three screw granulator

In order to reflect the extrusion of the head, it is necessary to detect the pressure of the extrusion head. Because there is no head pressure sensor in the three screw extruder made in China, it is generally the measurement of the pressure of the thrust after the extrusion of the screw extruder. The screw load meter (ammeter or voltmeter) can accurately reflect the pressure size of the extruder. The fluctuation of extrusion pressure is also one of the important factors that cause the instability of the extrusion mass. The fluctuation of extrusion pressure is closely related to the extrusion temperature, the use of the cooling device, the length of the continuous running time and so on. When abnormal phenomena occur, the rapid elimination of the elimination and the need to reorganize the production should be broken down, which can not only avoid the increase of waste products, but also prevent the occurrence of accidents. By detecting the pressure gauge reading, we can know the pressure state of plastic when extruding, and generally take the back thrust limit to alarm.

Control of 3. screw speed

The adjustment and stability of screw speed is one of the important technological requirements of main drive. The screw speed directly determines the amount of glue and extrusion speed.

The maximum speed and high yield can be realized. The speed range of the three screw extruder is required to be used when the screw speed is required from starting to the required working speed. And the stability of the speed is high, because the fluctuation of the speed will lead to the fluctuation of the extrusion quantity and influence the extrusion quality, so the change of the outer diameter of the cable will be caused without the change of the speed of the traction line. In the same way, such as the rapid fluctuation of the line speed of the traction device, the outer diameter of the cable will be changed. The speed of the screw and the traction line can be reflected by the corresponding instrument on the operating table. It should be closely observed during extrusion, so as to ensure high quality and high yield.

4. control of outer diameter

As described above, in order to ensure the size of the outer diameter of the cable, in addition to the dimension tolerance of the control line core (cable core), the control of the extrusion temperature, the screw speed and the line speed of the traction device should be guaranteed, and the measurement control of the outer diameter reflects the accuracy and the level of the above control. In the three screw extruder equipment, especially the high speed extrusion line, the on-line external diameter detector should be used, the external diameter of the cable is detected at any time, and the super differential signal is fed back to adjust the speed of the traction or screw, and the overdiameter of the outer diameter can be corrected.

5. tension control for rewinding requirements

In order to ensure the line at different speed, the requirement of constant tension from empty disk to full plate work, it is hoped that the winding device has the adjusting mechanism of the tension of the storage line, or the winding of the constant line speed system and the constant tension system is considered in electricity, etc.

The electrical automation control of the 6. whole machine

This is the process control requirement to realize the high speed extrusion line, mainly: the opening temperature interlocking, the working pressure protection and interlocking, the proportional synchronization control of the two main parts of the extrusion and traction, the synchronous control of the line and the traction, the on-line detection and feedback control of the outer diameter, the single and the whole machine which is composed of various parts according to the different needs. Tracking control.