I. Introduction Before the upgrade, the batching system of the 130m² sintering machine at Lianggong Steel had 18 electronic batching belt scales (hereinafter referred to as equipment). Due to a lack of system consideration in the initial design, the equipment was manufactured by multiple companies with diverse models and specifications, resulting in inconsistent equipment compatibility. Furthermore, the equipment had low batching capacity and was difficult to source spare parts. Especially with the commissioning of the new 180m² sintering machine, the two machines shared a dual-system inlet and outlet, increasing process control difficulty and multiplying production capacity. The electronic belt scales in the system were the same as those used in the original 130m² sintering machine, leading to frequent overload operation of the batching system. This resulted in rapid wear and tear on critical components such as the drive and transmission devices, high consumption, high equipment failure rate, and poor batching control accuracy. In particular, the domestically produced secondary weighing instruments lacked a bus configuration, had limited functionality, and could only transmit 4mA to 20mA signals to the PLC control, leading to large conversion errors and severely impacting the system's weighing accuracy. The 180m² sintering machine is based on the original 130m² sintering machine with the addition of two electronic batching belt scales for neutralizing powder silos. It is a key piece of equipment for realizing automatic control of the flow distribution during the batching process and automatic control of water addition during the first and second mixing stages. The main problems before the renovation were: ① The drop point height between the two discs in the material distribution chamber and the drop point of the conveyor belt used for weighing was too large (>700mm), resulting in a large impact force on the scale directly from the drop height. In addition, the effective weighing section of the scale was too small (<500mm), and the impact force from the drop height directly affected the accuracy of material measurement. This turned the high-precision electronic belt scale into an ordinary material conveyor belt in use, resulting in a waste of resources; ② The conveying flow rate of the two electronic batching belt scales used for material distribution was designed to be too small. In order to meet the sintering production, the belt speed of the scale had to be forcibly increased, which caused frequent tripping of the electrical control and seriously affected the normal operation of the equipment; ③ The two weighing conveyor belts selected were crudely manufactured, with a thin scale frame structure and poor rigidity and stability. They were not suitable for the expanded production capacity of the two sintering machines with a capacity of 130m2 and 180m2 (the original design capacity for material distribution and conveying was only 550t/h, while the current actual material distribution and conveying capacity requirements are 750t/h and 900t/h, respectively). Due to significant differences in the design capabilities of the equipment before the modification, the conveying capacity could not fully meet the sintering production requirements. In response to the above problems in the batching system of the 130 (180) m² sintering machine, and considering the development needs and process characteristics of sintering production, through comparison of technical solutions and repeated demonstrations of equipment modification and product selection, we began in February 2005 to modify the project by combining the advanced domestic weighing structure design with new foreign weighing display instruments with bus-based functions. This achieved a series of low-cost automation modification measures, resulting in low investment, quick results, and strong practicality. II. Modification Measures and Practice 1. The original two electronic batching belt scales in the 180 m² sintering machine's material distribution room were modified from a head and tail wheel center distance of 3500 mm to 3700 mm, with an effective weighing section distance of no less than 1000 mm. Considering the maximum flow rate required in practice, the power of the original two sets of variable frequency speed control motor reducers for the scales was increased from 4kW to 5.5kW and 7.5kW, respectively, to match the power of the existing frequency converters (7.5kVA and 11kVA, respectively), achieving the best effect of automatic speed control. 2. Based on the increased material distribution capacity of the two sintering machines, the redesign intentionally enhanced the structural strength and mechanical performance of the two new scales in the 180m² sintering machine distribution chamber. Simultaneously, the width of the belts used for the scales was increased from the original 800mm to 1200mm, with a thickness of 10mm, ensuring that material is not spilled during belt conveying, thereby improving the batching accuracy and service life. 3. To ensure the correct installation height of the weighing equipment and the correct material feeding position of the disc feeder, precise calculations were performed to match the maximum flow rate of the electronic batching belt scale with the discharge capacity of the same silo. Simultaneously, process modifications were made to the disc feeder positions of the quicklime silo and fine powder silo of the 130m² sintering machine and the two neutral powder silos in the 180m² sintering machine distribution chamber, as well as the installation locations of the equipment. This achieved the goals of improving metering accuracy, enhancing batching control precision, preventing material suspension, and ensuring uniform and stable material distribution. 4. All electronic batching belt scales were redesigned as a single-unit structure, eliminating the original worm gear two-stage transmission device and uniformly adopting an advanced domestically produced single-stage direct-drive shaft-mounted drive device. Furthermore, the existing weighing platform installation foundation (or mounting bracket) and silo space were utilized as much as possible in the new scale structure design, which not only saved a significant amount of process equipment modification costs but also accelerated the construction progress of these equipment modifications and installations. 5. Based on the requirements for online data sharing in the Lianggong ERP project, this upgrade selected the advanced MW696 intelligent weighing display instrument with MOD-BUS PLUS bus system from abroad. Through improvements and modifications to the original program, data is directly exchanged with the PLC via digital communication, completing data communication and acquisition. This not only eliminated the errors caused by the original analog data channel conversion but also improved the accuracy of batching control and realized the online management function of batching data. 6. The control section uses a fieldbus approach to acquire weighing data and set weighing parameters, overcoming the shortcomings of traditional 4mA-20mA signals, such as short transmission distance, poor anti-interference capability, large data conversion errors, inconvenient construction, and the need for expensive analog acquisition modules. Through fieldbus communication, the intelligent functions of the secondary instrument are fully utilized. In addition to data acquisition and remote setting, the workstation can complete a series of commands, including determining the batch weight based on the weighing completion signal from the instrument, remote triggering based on the error codes from the instrument, upper-level PID calculation, and fault alarms, and easily completing functions such as zeroing, tare, and forced accumulation. The control system software design achieves redundant signal acquisition. That is, the signal from the weighing sensor is acquired by a 4mA~20mA universal analog display module as a redundancy for bus acquisition, and acquired through the fieldbus. In this way, even if the analog channel on the scale instrument is damaged, or the bus interface is disconnected or damaged, the system can still operate normally. Redundancy design is also made in the frequency setting of the frequency converter. The frequency setting value can be output by the PID control program module written in the PLC and remotely set by the HMI screen. Alternatively, the PID built into the scale instrument can transmit a 4mA~20mA signal to the frequency setting input terminal of the frequency converter through its output terminal. III. Effects of the Modification and Application 1. Equipment Performance Through our scientific and reasonable technical improvement practice, the modified 130 (180) m2 sintering machine batching system electronic batching belt scale has a unified model, clear specifications, compact structure, novel appearance, superior performance, time-saving installation, simple maintenance, and convenient operation. The practice over the past year of operation has proven that the system weighs accurately and has good batching control. The single-machine weighing accuracy has improved from ±2.0% before the modification to ±0.5%, and the cumulative control error of the batching system has decreased from 4.5% before the modification to within 1.0%. The modified 130 (180) m2 sintering machine batching system has reached the advanced level at home and abroad compared with similar equipment at home and abroad (such as weighing structure, system control, functional characteristics, maintenance operation, technical indicators, performance-price ratio, etc.). 2. Automatic control level The system adopts low-cost automation modification. In the modification design, advanced intelligent weighing control instruments imported from abroad were boldly selected, and the relatively backward old-fashioned domestic secondary instruments were eliminated. The original automatic control configuration was changed to use MODBUS PLUS bus mode to directly exchange data with the existing QUENTUM PLC to complete data acquisition and PLC command issuance. The system hardware is advanced and reasonable. The application software design is unique. The data acquisition model and control function are modularly optimized and combined. The system logic control, sequential control, interlocking control, single-machine loop control and system main program control are networked, and the batching system equipment and personal safety measures are interlocked. The energy-saving and environmental protection program module, human-machine interface and information sharing are innovatively designed. The comprehensiveness and advancement of its automatic control technology have reached the advanced level in China. The system adopts a star Ethernet topology structure and a TCP/IP five-layer communication network model, connecting three workstations. It can not only monitor the batching process of the 130 (180) m2 sintering machine in real time and remotely, but also realize human-machine interface and online setting, online parameter tuning, further improving the advanced production management mode of unified scheduling and command and standardized operation of the sintering batching production process. 3. Technical and economic indicators were compared with the relevant production statistics and data analysis of the No. 3 sintering workshop of Lianggong Steel Plant before and after the transformation: (1) According to the fact that every 1.0% increase in batching accuracy contributes 0.5% to the sintering yield, the sintering output in 2005 after the transformation was 3.4934 million tons. The batching accuracy was 3.0% higher than that in 2004 before the transformation, so the sintering output increased by 52,400 tons; (2) The basicity stability rate of sintering in 2005 was 92.01%, which was 2.01% higher than the company's target plan and 2.27% higher than that in 2004 before the transformation; (3) The average drum strength of sintering increased from 75% before the transformation to 76.13% after the transformation. At the same time, the screening index was significantly improved and the content of -5mm particle size was significantly reduced; (4) The qualified rate of sintering in 2005 was 93.85%, which was 1.85% higher than the company's target plan and 2.29% higher than that in 2004 before the transformation. Therefore, the technical and economic indicators of the sintering production in 2005 after the system was modified also fully reached the advanced level of similar domestic systems. Practice has proven that the modification was successful. IV. System Principle and Control Method As shown in Figure 1, after the modification, the various raw materials (such as flux, neutralizing powder, coke powder, return ore, etc.) of the 130 (180) m2 sintering machine are weighed and detected by the electronic batching belt scale installed and debugged between the disc feeder and the hopper feeder and the collection belt conveyor. The voltage signal of the flow feedback value of each raw material can be obtained at regular intervals. The signal of the weighing sensor is sent to the weighing control instrument. After PI calculation, a 4mA~20mA control signal is output, or it is sent to the relevant module of PLC for processing via MB+ fieldbus. It is compared with the set value of the host computer. The PLC completes the PI calculation and sets the output frequency of the relevant frequency converter. The two PI calculations are selected by the hard-wired conversion switch on the control cabinet (or the PLC-PI calculation output or the instrument PI calculation output can be selected by the soft conversion switch on the host computer HMI screen). The speed encoder (sensor) in the batching belt scale measures the speed of the raw materials transported by the belt. It converts the rotation distance of the driven pulley into a pulse signal representing the speed of the raw materials on the belt, which is then sent to the weighing control instrument for adjustment and calculation to automatically control the flow rate. The system operates in three modes: manual feeding, where an external potentiometer provides an analog voltage to the frequency converter to adjust the motor speed; automatic feeding, where the desired feed rate is set via the weighing control instrument keyboard, and the frequency converter frequency (motor speed) is automatically adjusted based on the feed rate; and remote feeding via a host computer, where the PLC acquires 4mA-20mA signals from the secondary instrument via an analog module, or via MB+ fieldbus, allowing feeding settings to be configured through the HMI screen. Three workstations are connected to the PLC via Ethernet and integrated into the company's local area network, reliably completing batching data acquisition, communication, and information sharing, and also possessing production management capabilities that integrate with the Lianggong ERP system. V. Innovations in the Modification Design 1. Through structural modification design of the 130 (180) m2 sintering machine batching (distribution) electronic belt scale (see Figure 2), the overall mechanical performance of the scale has been improved. The structure adopts a single frame with multiple rollers, the structural coefficient of the scale frame is 0.5, the overload coefficient is 150%, the running stability is good, the measurement accuracy is high, and the service life is long. 2. The scale body structure is boldly innovated in the modification design, using high-quality thick-walled square tubes, the side of the frame is a "目" (eye) shaped structure, and the scale frame is a "日" (sun) shaped design. Rectangular profiles are used, which have high rigidity, low deflection, light weight, high strength, novelty and beauty, completely eliminating the traditional and backward all-channel steel structure of most domestic manufacturers. 3. The scale body support adopts a long shaft design, with high concentricity, low shaft friction, and a double-shaft spiral design with high-density small rubber bearings, which have good anti-torque performance and high reset accuracy. The scale body roller shaft and support shaft are both installed on the side, which has strong load-bearing capacity and good stability. 4. The suspension section of the scale body adopts a direct connection between spherical bearings and a short steel belt. This structure offers better resettableness and sensitivity than the previous spherical bearing or cross-spring connection methods. One year of field use has proven that this key technological innovation ensures the load signal received by the sensor is linearly consistent with the linear load perpendicular to the belt, guaranteeing high accuracy in material distribution. 5. To reduce the impact of the "belt effect" on measurement accuracy, this modification places the drive wheel at the receiving end, employing a cycloidal pinwheel and reducer for concentric transmission. This results in high transmission efficiency, good stability, and minimal sway. It completely eliminates measurement errors caused by scale body sway due to misalignment of the motor and reducer connections. 6. The weighing mechanism adopts a single-lever, double-roller, double-sensor mechanism. Its advantages and innovations lie in the weighing platform composed of two sets of rollers, with a longer lever arm, which maximizes the mitigation of measurement errors caused by uneven material conveying. Simultaneously, the use of dual sensors effectively overcomes measurement errors caused by belt misalignment (eccentric loading). 7. The modified batching scales are all designed with rear-wheel drive. The characteristic of the belt is that the upper layer is relaxed and the lower belt is taut when the belt is running, which can better overcome the weighing error caused by belt tension. The drive wheel is rubber-coated and drum-shaped. Because rubber coating can enhance the friction coefficient between the drive wheel and the belt, it can also eliminate the phenomenon of belt slippage when the belt is under heavy load. At the same time, the drum-shaped main and driven rollers also have the function of preventing belt deviation. During operation, there will be no batching control accuracy error caused by the forced belt correction. According to the process requirements of the 130 (180) m2 sintering machine with large and small flow rate raw material ratio, its drive device adopts BW type hard tooth surface cycloidal pinwheel reducer, and the coupling adopts claw-shaped rubber coupling. The direct connection installation method is adopted, which has the characteristics of no noise, low maintenance and convenient maintenance. 8. The 130 (180) m2 sintering machine has 6 disc batching scales with scrapers. Previously, a balance hammer was used to adjust the single-sided scraper rubber sheet. Long-term use was affected by the large flow rate of the disc batching, the high moisture content of the raw materials, the strong viscosity, and the large fluctuations in material conveying. This easily caused the single-sided scraper to wear quickly, the balance hammer to become light, the adjustment to become out of control, and the batching belt to scrape the material incompletely. As a result, the tare weight of the weighing was difficult to eliminate, which directly affected the batching control accuracy of the scale and the service life of the belt. In this renovation, the fluctuations of the belt conveyor were utilized to innovatively design a simple spring-type adjustment device for each balance hammer device. At the same time, the original single-sided scraper was changed to a double-sided rubber scraper, which ensured that the belt scraped the material cleanly. The scraper utilization rate was increased by 50%, the belt consumption rate was reduced by 52.5%, and the annual maintenance cost can be saved by more than 30,000 yuan. 9. After technical improvements to the weighing structure, we have a high-quality, low-cost batching and weighing testing device. Based on the requirements of the sintering process, and considering the expansion of some batching silos and the modification of process equipment, we have made reasonable adjustments to the installation height, material drop point, and effective weighing section distribution of each device. Due to the adoption of the superior performance of the new batching and weighing equipment, the original plan to replace 28 frequency converters was cancelled. Through precise calculations, the existing electrical control equipment was fully utilized, saving approximately 126,000 yuan in project investment. 10. Since the weighing instrument itself does not have a field-wide intelligent bus function, we adopted protocol conversion methods in this modification. Through a gateway, we converted the RS485 protocol of the weighing instrument to the MODBUS PLUS protocol, thus realizing protocol conversion functions between RS422/RS485←→MODBUS PLUS and RS422/RS485←→MODBUS. 11. We developed a program module based on energy saving and safety principles, with centralized/local control modes and centralized automatic/centralized manual operation modes on the HMⅡ screen. In centralized automatic control mode, PID control offers high adjustment accuracy and employs flow feedforward technology, resulting in strong anti-interference capabilities and achieving precise frequency conversion and energy saving. Simultaneously, it fully utilizes the status codes fed back from instruments for real-time comprehensive monitoring of field equipment, providing a more comprehensive reflection of field fault conditions than purely hard-wired methods, ensuring the safety of personnel and equipment. VI. Conclusion Considering the complex source, large compositional fluctuations, and numerous impurities of raw materials at Lian Steel, this transformation aimed to digest and master advanced domestic batching processes and equipment technologies, boldly innovate, and strive to improve the accuracy of the electronic batching belt scale. Production practice has proven that with the improvement of batching accuracy, the yield of sintered ore significantly increases. According to relevant statistics and our own past data analysis, every 1% increase in batching accuracy leads to a 0.5% increase in the yield of sintered ore. In 2005, the No. 3 sintering workshop of Lianggong Steel's sintering plant produced a total of 3.4934 million tons of sintered ore. After the upgrade, the accuracy of the batching process improved by 3%, increasing output by 52,400 tons. This ensured stable process control during sintering, providing fundamental support for Lianggong Steel's historic achievement of 5 million tons of output in 2005. It also strongly guaranteed Lianggong Steel's iron production of 3.75 million tons and steel production of 4.1 million tons. The successful implementation of this system upgrade design can generate annual economic benefits of over 10 million yuan.