Application of PLC in Control System of Straight Line Wire Drawing Machine

1. Design of PLC Part in Straight Line Wire Drawing Machine

The relay output type can be connected to a variety of special function expansion modules to realize a variety of special control functions, control parameters can be set, complex data operations can be processed, and strong logic control functions and PID process control can be realized, providing maximum flexibility for factory automation applications Sex and control ability, high reliability, small size and low cost, meet the design requirements of this system. The basic unit of PLC has a corresponding asynchronous serial communication port, which is used for programming and debugging of the wire drawing machine control system, as well as communication and control with other industrial control equipment. The expansion interface of the basic unit is used to connect with special function modules, connect analog input modules and analog output modules.

2. Analog Module Design of Straight Line Wire Drawing Machine

The analog input module has four channels to collect voltage signals or current signals. Each channel can perform AD conversion with a resolution of 12 bits. There are 32 16-bit buffer registers inside for exchanging data with PLC. The analog output module is used to convert the 12-bit digital quantity into two analog voltage signals or current signals to drive the load through the actuator, and the analog quantity module is used to complete the PID closed-loop control of the system.

3. Frequency Converter Design of Straight Line Wire Drawing Machine

The inverter can change the driving speed of the motor by changing the frequency of the power supply, and then achieve the purpose of energy saving and speed regulation. The inverter also has many protection functions, such as overcurrent, overvoltage, overload protection and so on. The frequency converter is used in the design of the control system of the wire drawing machine in China. The input of the frequency converter is single-phase, the output is three-phase, the wiring is convenient, the operation is reliable, and the hardware requirements of the system are met. The application of frequency converter greatly improves the automation level and processing capacity of the wire drawing machine, effectively reduces the energy consumption and maintenance cost of the equipment, and realizes the stepless speed regulation control of wire drawing and the constant tension synchronous control of coiling.

4. Debugging Design of Straight Line Wire Drawing Machine System

During the whole debugging process of the wire drawing machine, not only should the feedback proportional coefficient be adjusted reasonably, but also the difference in the output of the wire drawing machine during normal operation should be paid attention to. The whole system can be divided into starting, accelerating, decelerating, stopping and other processes during operation. The latter stage follows the speed change of the previous stage. The speed setting of the drawing motor of the latter stage adopts compound control, and the output after adjustment of the analog feedback signal is used as auxiliary setting. The starting requirement of the first drawing motor has a higher starting torque should also be sufficient when pulling the maximum wire diameter. During the acceleration process of the take-up line, the acceleration time is shorter than that of the slave pull, because the take-up line needs to respond more quickly to the change of the speed of the main pull or the slave pull. In the process of deceleration and parking, it is also necessary to set the deceleration time of the main pull, slave pull and take-up motor of the wire drawing link, so as to ensure that it can stop near the balance position when parking.

The programmable controller, touch screen and frequency converter are used to provide a mechatronic system solution for the straight line wire drawing machine equipment. The actual effect has reached the expected design and the automation degree of the wire drawing machine has been improved. The speed of the pay-off motor can be adjusted according to the different specifications of the cables by using frequency converter control, which improves the product accuracy and system stability. The frequency conversion control of the system realizes the soft start of the motor, prolongs the service life of the motor, and reduces the amount of electrical maintenance.