Application Of Mitsubishi Fx2n-plc And Inverter In Rubber Extruder

1. Systematic overview
　　Modern electronic and computer control technology has been widely used in extruders in developed countries. The parameters of extrusion process, such as melt pressure and temperature, fuselage temperature, rotational speed of main screw and feeding screw, feeding quantity, ratio of various raw materials, current and voltage of motor, are measured on-line by means of computer. closed-loop controlMitsubishi FX2N-PLC Some companies have adopted network remote monitoring, diagnosis and control to control the frequency converter for extrusion production line, which is very helpful to ensure the stability of process conditions and improve the accuracy of products.
With the compounding of extruder, its mechanical performance will be more complex, and the control system matching with it will be more complex, and the control precision will be higher. Therefore, how to design the appropriate control system to ensure its economic, safe and reliable operation, and not become a phased-out or transitional product in a short time? In the control of multi-compound extruder, the bus technology and network structure are simple and the technical performance is stable, which not only greatly reduces the wiring quantity, facilitates installation, debugging and maintenance, but also greatly enhances the flexibility and reliability of the system. At the same time, good social and economic benefits have been achieved in rubber extruder.

The development of new screw extruder with small shrinkage and deformation, high dimensional accuracy and high extrusion speed, and the continuous maturity of compound extrusion technology, in recent years, the rubber industry has developed rapidly, which has promoted the rapid development of rubber extrusion technology in China. The compound extrusion technology of radial tire can be called rubber extrusion. Typical representative of technical level.

2. Process characteristics
　　Generally, according to the type of polymer processed and the shape of products or semi-finished products, the extruder, die and die are selected, and the corresponding auxiliary devices such as setting and traction are selected. Then the extrusion process conditions such as screw speed, head pressure, material temperature, setting temperature and traction speed are determined. In the extrusion process, materials are usually processed, but the method of setting is different. For example, extruded plastics often need to be cooled and cured, while semi-finished products of extruded rubber need further vulcanization. Different products can be obtained by using different extrusion equipment and processes.

Figure 1 Extruder equipment
3. Composition of Control System
Modern electronic instruments and PLC control technology have been widely used in extruders. The parameters of extrusion process, such as melt pressure and temperature, fuselage temperature, rotational speed of main screw and feeding screw, feeding quantity, ratio of various raw materials, current and voltage of motor, are measured on-line, and closed-loop control of frequency converter is adopted. This is the case. PLC monitoring, diagnosis and control are used to control the speed of extrusion production line automatically. This is very helpful to ensure the stability of process conditions and improve the accuracy of products.

With the compounding of extruders, the mechanical properties of extruders must be more complex, and the control system matched with extruders will also be more complex, and the control accuracy will be higher. Therefore, how to design a suitable control system to ensure its economic, safe and reliable operation, and not to become obsolete or transitional products in a short time, is a problem that our engineers must consider.

New type screw extruder with small shrinkage deformation, high dimensional accuracy and high extrusion speed has been developed and compound co-extrusion technology has been maturing. In recent years, the rapid development of rubber industry has promoted the rapid upgrading of rubber extrusion technology in China.

The main function of the extruder control system is to control the screw speed, barrel temperature and melt pressure in the extrusion process. At present, instrument control system and PLC control system are the main choices. The functions of the two systems are as follows: the instrument control system in temperature control can realize switching control and the intelligent instrument can realize simple ratio control, while the PLC control system can realize PID (ratio-integral-differential control) control through analog communication; the former can display melt pressure, while the latter can display melt pressure. Pressure and closed-loop control are realized; the former has only display function, while the latter can realize serial communication of test unit. The control system of the extruder is mainly composed of electrical, instrumentation and actuator. Its main functions are as follows:     

(1) Controlling the driving motor of the main and auxiliary machines to meet the speed and power required by the process, and ensuring the coordinated operation of the main and auxiliary functions.

(2) Control the temperature, pressure, flow rate and product quality of the main and auxiliary machines.

(3) Realize the automatic control of the whole unit.

(4) Data acquisition and processing to achieve closed-loop control.

　　The extruder controls all motor and temperature setting by FX2N series programmable controller and GT1045-QSBD man-machine interface as the center of the circuit system. The input includes self-stop switch, thermal relay, sensor and encoder. The speed and process parameters of each motor are controlled by PLC. Touch screen is used to set and display extrusion speed, pressure, temperature control in each area. Switching signals are sent to the frequency converter through PLC to control the start and stop of the frequency converter. The alarm signals such as frequency converter and motor are sent to touch screen to display the type of fault and so on. 235 communication is used between PLC and touch screen. The above process parameters and operation signals are sent to PLC through 235 communication. After data processing, analysis and calculation, 485 communication signals are passed by PLC to control the speed of the corresponding converter.

Figure 2 Flow chart of extruder control system
                   
List of main electrical components of the system
3.1. Frequency Converter FR-A740-90K-CHT    1 set
3.2. Encoder E6B2-CWZ6C/1000  1 set
3.3. FX Programmable Controller FX2N-32MT-001 1
3.4, FX communication card FX2N-485-BD    1 set
3.5. Touch screen GT1045-QSBD   1 set
4 system debugging
A FX2N programmable controller and a man-machine interface constitute two GT1045-QSBD man-machine interface control motor speed control, temperature, pressure and other working conditions.
FR-E740-90K-CHT has encoder feedback to accurately control the speed of the motor and realize closed-loop control of the speed of the motor. As long as there is a fault action, it will stop working. At the same time, GT1045-QSBD man-machine interface jumps to the fault display screen. On the screen, we can see the causes of the failure of the corresponding parts of the extruder. The fault part has detailed text description. This is the case. Man-machine interface provides users with four groups of pictures, respectively.“Introduction to Start-up”And“Parameter Setting”And“Manual adjustment”And“running state”This is the case.

Figure 3 Touch screen screen
          
　　The speed of frequency conversion is adjustable, and the speed of feed frequency conversion is controlled by the feedback signal of the encoder. The closed-loop control is realized to achieve accurate speed control.
The speed of frequency conversion and compensation are input by the user through touch screen. After receiving the data input by touch screen, the PLC transmits the data to the frequency converter through communication module after calculation and processing. Temperature control is controlled by instrument. PLC communicates with instrument 485. Temperature can be seen and set on touch screen.
 Operation of 4.2.2 Frequency Conversion Speed Regulation System
(1) The operating frequency of the frequency converter is set on the touch screen, transmitted to the PLC by means of communication, and then transmitted to the frequency converter by means of communication module.
(2) The starting, stopping and speed switching instructions of the frequency converter are sent out by the operator on the industrial touch screen, and the switching signal is transmitted to the corresponding input end of the frequency converter by the output end of the PLC.
(3) After receiving the above instructions, the frequency converter starts to run according to the instructions. In operation, the encoder connected with the motor coaxially feeds back the actual detected pulse to the PLC, which performs the calculation and processing.
(4) If the frequency conversion fails to alarm, the open collector output point sends the signal to the PLC input point. The frequency conversion system immediately stops running, and the touch screen immediately displays the fault category and troubleshooting method, and its response speed is very fast.
4.2.3 Partial Setting of Frequency Conversion Parameters
Parameter number
Name
Factory settings
Current value
71
Applicable motor
0
13
340
Communication startup mode selection
0
1
77
Parameter Write Selection
0
2
79
Operating Mode Selection
0
2
80
Motor capacity
9999
90KW
81
Motor pole number
9999
6
96
Automatic tuning settings and states
0
1
After the PLC, man-machine interface and frequency converter are working normally, the PLC program is compiled for system debugging. The PLC system is programmed on the computer through GX-Developer software. Figure 4 is the ladder diagram of the program design part.

Figure 4 Program Communication Section of Extruder  

Fig. 5 Program Communication Section of Extruder
 

Figure 6 Program Communication Section of Extruder

Figure 7 Extruder Program Communication Section
                
In the process of debugging, we will encounter many problems, and many of them are not handled well. We need to work step by step. If there is an alarm, we will check the relevant books.
5. System Advantages
5.1. The whole control system of the extruder is composed of PLC and man-machine interface, which greatly improves the stability and reliability of the extruder production, is not easily disturbed and has low failure rate.
5.2. The operation is more convenient, the speed control is more accurate and the adjustment is convenient.
5.3. It improves the efficiency of extruder, simplifies operation, reduces consumption and reduces labor intensity.
6. Summary
　　The extruder adopts Mitsubishi programmable controller as the core control, combined with frequency conversion closed-loop control and touch screen debugging to solve the problems of current potentiometer speed regulation, inconvenient operation, poor stability and great improvement of the control level of the whole electronic control system, which reflects the development direction of electric control of extruder in China today. Mitsubishi's FA products have been recognized by more and more customers through many years'use and good cost performance.