Abstract: In view of the situation that many domestic drawing machines adopt AC speed regulation and single frequency conversion control, an integrated scheme of the whole system electrical control based on more accurate frequency conversion control technology was developed and designed. Firstly, the overall integrated design scheme of the whole electrical control system of the drawing machine equipment is proposed, and then the drawing stepless speed control and the constant tension control of the drawing wire in the electrical control of the drawing machine equipment are emphatically introduced, finally, the realization process based on the integrated scheme of the electrical control is introduced. The electrical integrated control drawing machine has the advantages of high flexibility, strong stability, simple operation and convenient maintenance, which lays a foundation for the practical application of the integrated scheme of the whole system electrical control of the frequency conversion control technology.

         In recent years, with the rapid development of China's automobile industry and highway industry, steel cord as the main material for manufacturing radial tire has become a hot spot in the market. As a wire equipment for producing steel cord, it has gained considerable development. The wire drawing machine is mainly used in the processing of copper wire, stainless steel wire and other metal cable materials, which is a very important processing equipment in the cable manufacturing industry. At present, domestic wire drawing machine equipment mostly adopts AC speed regulation, single frequency conversion control wire drawing machine [1]. However, due to the single frequency conversion control of the drawing machine slip is too large, in the energy saving, further reduce the production unit cost and slightly insufficient, the reason is that the production process of congenital reactive power loss leads to the consumption of electricity, the finished line is microscopic grain, metal powder particle adhesion is high. For enameled wire production enterprises, seriously affect the quality of copper wire enameled (mainly reflected in the on-line pressure test pass rate). On the occasion of copper wire requirements are relatively high, this control method often can not meet user requirements. In order to solve the drawing principle of guide, single frequency converter and mechanical mechanism optimization, not perfect any defects of single frequency conversion control system, this paper puts forward a more accurate frequency conversion control technology of the integration scheme of electric control in the system, the scheme is introduced drawing machine equipment gas drawing infinitely adjustable-speed control and accept line in the control of constant tension control, through the tension in figure 1 the motion of the rocker, back to the drawing machine integrated control system, automatically by the system calculation, part change for supply and exhaust speed so as to achieve winding and drawing two links of the constant tension and speed synchronization [2].

          The electrical integrated control drawing machine has the advantages of high flexibility, strong stability, simple operation and convenient maintenance. It realizes the synchronization of constant tension and speed in drawing and coiling of the drawing machine equipment, and has been successfully applied to the actual production of drawing with good results.

        1. The overall integrated design scheme of the whole electrical control system

         The whole system of the drawing machine equipment is composed of four parts: frequency conversion speed control, main controller system, detection and alarm, touch screen display technology. Each subsystem connects and communicates through RS485 bus, and each frequency converter communicates through Modbus. Among them,RS485 has high transmission rate, long transmission distance, strong anti-interference ability, and the emergence of earlier RS232 and TTL level is not compatible, low transmission rate, limited transmission distance, weak anti-interference ability, so this scheme chose RS485. Modbus communication protocol is a universal language applied to electronic controllers. Through this protocol, each controller between each other, each controller and other devices can communicate with each other. It has become a universal industry standard. With it, control equipment produced by different manufacturers can be linked into an industrial network for centralized monitoring. The system structure and composition block diagram are shown in Figure 2. Drawing machine equipment is a typical mechatronics equipment, its integrated control system includes the following four aspects: (1) control system structure; (2) Modbu S communication technology; (3) Tension control strategy; (4) measures to improve reliability, etc.

图2  控制系统结构图

       2. Realization of the whole system integration design of electrical control System hardware composition is shown in Figure 3.

        Main controller: the main control loop of the drawing machine adopts programmable controller with high reliability and stability and human-machine interface programming control. The drawing length is detected by meter sensor and fed back to the main controller. The machine has normal and fast stop, preset speed and fixed length, digital acceleration and deceleration, fault alarm and tension automatic tracking and other functions. It can be started and stopped at any time, without the phenomenon of broken wire and chaotic wire. It has the characteristics of reasonable structure, stable performance, complete functions, simple operation and convenient maintenance. Transmission part of the frequency control of motor speed control: wire drawing machine control, main is to ensure that the take-up motor accurately as the main motor speed change and winding wheel diameter increases, automatically adjust the speed, timely and accurate complete systems to ensure constant tension, to ensure continuous stability of steel wire in the whole drawing process, ensure the quality of steel wire products. In the process of operation, the two motors' running speed and accuracy should be high, the dynamic transition process should be fast, the anti-interference ability should be strong, and the tension stability should be guaranteed. In addition, because the drawn steel wire should be evenly wound on the rewinding I-wheel, the whole system is equipped with a wire arrangement mechanism, using the frequency converter to control the reducer motor, according to the actual use of the process of real-time change of the wire arrangement speed, to ensure that the steel wire is evenly wound on the rewinding I-wheel. The speed control precision of frequency converter is high, so the VFT series vector type frequency converter is used for frequency conversion speed control. The speed precision of this series of frequency converter when the closed-loop speed control mode is running is: 1.5 r /m in when < 1 500r /m in; The torque precision of the closed loop speed control mode is: 5% of the rated torque. Using MODBUS communication mode for the three bus control of frequency converter, can collect real-time data in the practical application and given the order, to accurately control system, main control principle is: first of all the products according to the production material structure and the technological requirements set speed value on man-machine interface, through the PLC internal operations, the data written to the host inverter, the machine will run according to the given speed value, in the actual processing according to the need to change at any time during the process of numerical value, to meet the needs of the machining process. The set of winding frequency converter is to adopt analog signal feedback, through its own integral separation PID adjustment function, automatically track the speed of the host, the host and winding motor are using encoder as closed-loop feedback, to ensure the accuracy of speed following. In order to avoid some accident happens to cause in the process of the machine and the influence of personal safety, the machine is equipped with a variety of automatic protection, PLC automatic converter internal related data and real time operation, to make the machine to ensure the quality of products is not affected under the premise of stop quickly, to a large extent ensure the personal safety, avoid to cause unnecessary economic losses. On line control, in order to avoid frequently line edge is not neat, pressure and drum-shaped specific problems, such as silk, this system adopted a row line automatic compensation system, according to the line level is not flatness, automatic calculation in the process of practical work roll diameter and in real time correction, ensure the wire at any time and speed can even winding, reliably solve the trouble of ply of next working procedure, greatly improving the production efficiency.

                                                                                               Fig. 3 System hardware composition diagram

            Human-machine interface (HMI) is a medium and dialogue interface for information transmission and exchange between human and computer. It is an important part of computer system. It enables the conversion between the internal form of computer information and the form that can be accepted by humans. The system adopts advanced touch screen display technology, which can display the working state and main parameters of the drawing machine, and adopts graphical menu mode. When the system has a fault, it will display the fault warning and reason to remind the operator to check. Human-machine interface has automatic management system, compared with the general system has the advantages of consistent design, personalized function, communication function, and visual effect, has a considerable intelligence, greatly convenient for the user's operation. Monitoring and alarm: Because of the particularity of steel cord industry, when in actual use, tend to be mass production, each operator must control several or even dozens of machine at the same time, this needs to have a high level of intelligent machine, the machine all the parameters can be displayed intuitively, convenient operator timely solve the problems and improve the efficiency of production, so the important indicators of wire drawing machine and can reflect the fault information on the display panel, the operator can according to these information intuitively know whether the operation condition of the machine is now normal, if there is a fault is what reason, and so on, greatly improving the production efficiency, So as to meet the needs of mass production. The monitoring and alarm system of this case mainly uses a special controller to achieve the purpose of intelligence. This special controller not only has the control of motor and output under various states such as inching, running and stopping, but also has perfect protection mechanism such as broken line and frequency converter fault detection and alarm. In addition, the controller also integrates real-time speed detection, slip control, drawing length calculation, real-time clock and other functions, the operation is very convenient, once the production process and user set the above situation has a difference with the timely stop alarm and display the fault content, the controller has strong information and intelligence.

         3. Conclusion

         There are many kinds of integrated design of the whole system electrical control of the drawing machine equipment. The above control scheme greatly improves the drawing machine

        The automation level and processing capacity of the equipment can effectively reduce the unit energy consumption and maintenance cost of the equipment, and save a lot of human resources. It has been applied in a mechanical and electrical factory.