Abstract: Steel plate leveling and shearing machines are important equipment in steel plate plants and steel warehouses. Addressing the problems of low control precision in traditional shearing machine systems, an automatic control system for a 460mm wide coiled steel plate leveling and shearing machine based on Delta industrial control products was developed. This paper mainly discusses some key technical details in the system design and development process. Practical application in production demonstrates the success of the system design, its high control precision, and its stable and reliable operation. With appropriate modifications, it can also be applied to similar intermittent shearing systems, making it worthy of widespread application. Keywords: Fixed-length shearing, rapid positioning algorithm, shearing control system 1 Introduction The wide coiled steel plates produced by plate mills generally need to be leveled and sheared before becoming the final product for customers. Therefore, steel plate leveling and shearing machines are important production equipment in steel plate plants and plate warehouses. Due to numerous problems in the use of traditional shearing machines, and addressing the issues of low production efficiency and low shearing positioning accuracy in traditional steel plate leveling shearing machines, an automatic control system for a 460mm wide coiled steel plate leveling shearing machine based on Delta industrial control products was developed. This system has been put into production use, operating stably and reliably, with high control accuracy and convenient maintenance, receiving positive feedback from users. This article discusses some key technologies and engineering implementation-related issues during the development process from a technological perspective. 2. Introduction to Steel Plate Cutting Process and Problems with Traditional Cutting Control 2.1 Introduction to Cutting Process Flow As shown in Figure 1, the cutting system consists of five subsystems: feeding, leveling, cutting, belt conveying, and finished product stacking. The raw material coil (approximately 3-5mm thick steel plate) is fed by a feeder and flattener, then conveyed through a 4m long buffer pit to the leveling subsystem for leveling and positioning. After positioning according to the given cutting length requirements, the cutting machine cuts the steel plate into finished products, which are finally conveyed by belt conveyor for stacking and packaging. During system operation, photoelectric switches located in the pit are used to start or stop the feeder based on the degree of steel plate sagging, ensuring that the feeding speed matches the leveling machine's operating speed. Operators can input the length of each cut and the number of cuts via a touchscreen human-machine interface. Once set, the system automatically starts operating. Specific technical requirements for the cutting process are: the leveling shearing machine must achieve a cutting speed of 8 cuts per minute when the cutting length is 2m, with a relative error in steel plate length within 5mm. [align=center]Figure 1 Cutting Process Flowchart[/align] 2.2 Process Data Requirements Based on the cutting process requirements and physical calculations, the relevant technical data configuration to meet the process technical indicators is as follows: feeder power, 7.5kW; frequency calibration machine geared motor power, 3.7kW, reduction ratio, 15:1; plate cutter motor power, 4kW; belt conveyor motor power, 3.7kW; frequency calibration machine roller diameter, 108mm; encoder resolution, 500ppr; feeder maximum speed, 25m/min; plate cutter speed, 60 times/min; raw material steel plate thickness, 3-5mm, width less than 460mm; buffer pit: 4m long, 3m deep. 2.3 Problems with Traditional Cutting Control Systems Designing such a control system according to the above process data requirements is not difficult, but due to the defects of traditional solutions, many regrets are often left. For low-end equipment, traditional methods typically employ DC speed control systems. The disadvantages of this approach are: bulky systems, high power consumption, complex debugging, and high maintenance costs. In terms of positioning control, a method using pre-deceleration combined with pneumatic braking after reading limit switch signals is generally adopted, resulting in very low cutting efficiency and large errors. For high-end equipment, DC servo technology is generally used. While accuracy and efficiency are guaranteed, the price is very high, making the product's performance-to-price ratio unsatisfactory. With the rapid development of computer technology, automatic control technology, and vector frequency conversion speed control technology, how to construct a cutting control system with excellent performance-to-price ratio using advanced control technology has become a focus of attention. Delta Electronics provides a comprehensive control solution based on Delta industrial control products, which effectively solves the existing problems. 3. Automatic Cutting Control System Based on Delta Industrial Control Products 3.1 Introduction to Control Principle The overall solution control block diagram of the cutting control system based on Delta industrial control products is shown in Figure 2. The system uses an encoder, PLC, and vector frequency converter to form an automatic control system for precise positioning. Length positioning uses a Delta 500PPR encoder directly connected to a leveling feed roller for accurate measurement. The leveling machine is driven by a 3.7kW geared motor with a reduction ratio of 15:1. An electromagnetic brake is used to forcibly overcome the inertia of the moving steel, facilitating accurate positioning of the workpiece. A touchscreen human-machine interface serves as the window for command and data transmission, communicating with the DVP16EH00R via the HMI. Data and commands are then transmitted to the PLC-controlled field devices. In the positioning system, the Delta EH incorporates a fully open classic PID instruction. Using this instruction as the core, the calculation results can be easily and quickly dynamically corrected during PID calculations. All key parameters, such as P/I/D, can be adjusted at any time. This dynamic correction of the control algorithm compensates for the lag in the asynchronous motor's response. The dynamic PID continuous positioning algorithm enables the vector inverter in speed mode to control the asynchronous motor's positioning very accurately. Under this algorithm, the given speed of the frequency converter is in a changing state. The speed setting and status detection are completed through high-speed communication (115200 BPS) between the PLC's built-in RS485 interface and the frequency converter's built-in RS485 interface. This replaces the function that originally required an AC servo in a low-cost manner, achieving accurate cutting length control. Various DI signals from field devices in the system are fed back to the DVP-EH programmable controller. After calculation, the results are output to the actuator for execution to achieve safe, reliable, and stable control. [align=center] Figure 2 Control block diagram of the overall solution[/align] 3.2 Key Data Calculation and Control Scheme Description The roller diameter is 108mm, and the circumference is 3.1415 * 108 = 339mm. The encoder uses a 2x frequency counting method, so the encoder counting accuracy is 339/1000 = 0.339mm. The cutting time for each cut is 1 second, and the roller driving the board at a speed of 30m/min can meet the requirements. If we calculate based on an acceleration time of 2 seconds to reach maximum speed and a deceleration time of 2 seconds to 0, the system operates at maximum speed for 60 - 8 - 4 * 8 = 20 seconds per minute. The distance traveled per minute is 20 * 30 / 60 + 30 * 4 * 8 * 0.5 / 60 = 18 meters, which meets the requirement of 2 * 8 = 16 meters per minute. The PLC counting frequency is (30 * 1000 / 0.339) / 60 = 1475 Hz < 3 kHz. A Delta ES series PLC can meet the requirements. Using a geared motor with a rated speed of 1450 r/min and a reduction ratio of 15:1, the speed is 1450 / 15 = 96 r/min. The roller diameter is 108 mm, and the linear speed is 3.1415 * 108 * 96 / 1000 = 32.7 m/min, which is greater than the calculated maximum speed of 30 m/min, therefore meeting the requirements. The set parameters and PLC-automatically corrected data are stored in the PLC's power-off retention area (EEPROM area), ensuring data integrity. The HMI has a battery backup data retention area (64KB) to store important process history data. The HMI can perform secondary processing on the PLC data, such as alarm recording and display. Furthermore, it can be flexibly designed to meet other specified requirements based on customer needs. For remote monitoring, an EH expansion interface can be used to extend a third serial port, enabling dual control via both remote and on-site HMIs. 3.3 Safety and Reliability Considerations: Each part of the system is equipped with motor operation buttons, emergency stop buttons, and manual/automatic selection. All frequency converters are centrally installed in the control cabinet, while the PLC and HMI are placed on the field equipment. This configuration shortens the communication distance between the PLC and HMI, reduces interference from the frequency converters to low-voltage systems, especially encoders, and improves both communication reliability and control accuracy while also enhancing operational convenience. Frequency converters and power distribution equipment are kept away from signal equipment to prevent high-voltage interference with small signals and improve accuracy. Electrical distribution cabinet design considerations: 1) The power distribution system controls each circuit independently, with features such as circulating air cooling, backup power, backup buttons, and indicators, facilitating maintenance and modification; 2) The field power supply, interlocking power supply, and low-voltage power supply system are all equipped with air switches to prevent mutual interference from power short circuits; 3) Five-wire three-phase power supply, with separate neutral and ground wires in the distribution cabinet, which is beneficial for anti-interference and operator safety. 3.4 Field Application and System Design Description: The use of vector frequency converters, 15:1 geared motors, and electromagnetic brakes effectively overcomes the influence of inertia on positioning and the impact of the feeder, improving cutting accuracy. Many factors affect accuracy, such as encoder interference, the gap between the motor and coupling, the backlash of the coupling, the gap between the encoder and coupling, and slippage between the material and the roller during movement and stopping. Therefore, in addition to using high-precision encoders, vector frequency converters, and fast-response electromagnetic brakes in the design, it is essential to minimize the backlash of the coupling and increase the friction between the sheet metal and the rollers during installation and commissioning. To ensure the speeds of the feeder and the leveler are compatible, a pit can be dug between them for buffering. For example, if the feeder feeds at 16 m/s and the leveler cuts plates in 2 m increments, a 2 m margin is required. A 3 m long and 2 m deep pit can provide this 2 m margin for speed matching. However, it's impossible to pull the steel plates horizontally or to reach the bottom of the pit. Therefore, a pair of photoelectric switches are installed at an appropriate location at the bottom of the pit to detect over-limit signals. If the limit is exceeded, the feeder is activated. For convenience, a 4 m long and 3 m deep pit can meet the process requirements. [align=center]Table 1 Main Control Components and Devices[/align] The main control components and devices selected for the system are shown in Table 1. The following issues deserve attention in the system design. 1) The vector inverter selected is the Delta VFD-V series. This product has an extremely high performance-to-price ratio. Paired with the high-frequency, wide-response position closed-loop control card PG05, it can greatly improve the response characteristics of asynchronous motors. 2) The human-machine interface selected is the Delta DOP-A series 5.7' blue screen touch screen. This product has an exquisite appearance, is simple to develop, use, and maintain, and has an extremely high performance-to-price ratio among similar products. Its powerful software functions fully meet the application requirements of similar systems. 3) The encoder selected is the high-precision, high-reliability Delta ES encoder. The core grating code disk of this product uses Delta's patented laser etching technology and is combined with patented photoelectric conversion technology, which makes the output pulse edges clean while maintaining the characteristic that the high-frequency pulse output will not be deformed or lost. 4) The PLC is the Delta EH series. This series of products uses ASIC chips to process arithmetic instructions in hardware, which greatly improves processing speed and reliability. A small PLC can achieve the functions of a medium-sized PLC. 4. Conclusion The automatic control system for a 460mm wide coiled steel plate leveling and shearing machine, based on Delta's industrial control product solution, has demonstrated the following results after being put into practical production: 1) The solution offers high cutting accuracy, fully meeting user requirements, and is easy to operate; 2) A simple combination of an asynchronous motor, vector frequency converter, and high-speed PLC can achieve rapid fixed-length control, offering a high performance-price ratio that meets practical engineering needs and market demands; 3) An improved PID algorithm enables bandwidth response control of the vector frequency converter and asynchronous motor.