How to control the tension fluctuation of wire during high-speed drawing process in High-Speed Precision Wire Drawing Machine

        In the field of precision machining of metal wires, High-Speed Precision Wire Drawing Machine are the core equipment for the refined production of copper wires, aluminum wires, stainless steel micro wires, alloy wires and other products. With the continuous upgrading of downstream industries such as new energy, electronic communication, precision instruments, and automotive wiring harnesses' requirements for wire size accuracy, surface smoothness, and mechanical consistency, the high-speed, high-precision, and high stability of wire drawing production have become the core development trend of the industry. Under high-speed wire drawing conditions, even small fluctuations in wire tension can directly cause quality defects such as uneven wire thickness, surface scratches, wire breakage, excessive residual stress, and loose winding, greatly reducing product qualification rate and production efficiency. Therefore, precise suppression and dynamic cancellation of wire tension fluctuations, and the construction of a full process constant tension control system, are the core key to ensuring stable high-speed precision wire drawing production and improving wire quality. This article systematically analyzes the core causes of tension fluctuations in high-speed wire drawing processes, and provides a detailed explanation of standardized and high-precision tension fluctuation control technologies and complete solutions, providing professional technical references for industrial precision wire drawing production.

1、 The core causes of tension fluctuations in wire during high-speed drawing process

        The operating speed of high-speed precision wire drawing machines can reach hundreds to thousands of meters per minute. Under continuous high-speed drawing conditions, tension fluctuations are a systemic problem caused by multiple factor coupling, covering four dimensions: mechanical structure, process parameters, control system, and production environment. Accurate positioning is a prerequisite for achieving efficient wave control.

1.1 Mechanical Structure and Transmission Error

        The roundness deviation, surface wear, and coaxiality error of the tower wheel, traction wheel, and winding reel of the wire drawing machine can cause periodic fluctuations in the wire running speed, directly triggering tension pulse like changes. At the same time, traditional split transmission structures suffer from transmission gaps and mechanical inertia lag. During high-speed start stop and speed switching processes, the synchronization deviation of each process transmission is exacerbated, resulting in sudden increases and decreases in wire tension. In addition, mold wear and half angle deviation of the mold can cause periodic tension fluctuations, which continuously interfere with the stability of the pulling tension. The fluctuation amplitude will gradually expand under long-term operation.

1.2 Fluctuations in Process and Material Characteristics

        The material uniformity deviation, diameter tolerance fluctuation, and uneven hardness of wire raw materials can cause continuous changes in the tensile resistance of wire under the same drawing parameters, resulting in sustained tension fluctuations. At the same time, during the high-speed wire drawing process, friction heating of the wire and fluctuations in the cooling efficiency of the emulsion can cause temperature changes in the wire, leading to dynamic changes in the mechanical properties of the wire and resulting in thermal coupling type tension deviation. In addition, unreasonable ratio of drawing passes, imbalanced compression ratio parameters, and unstable flow and concentration of lubricating media will further amplify the amplitude of tension fluctuations.

1.3 Control system response lag and insufficient accuracy

        Traditional wire drawing equipment adopts open-loop or simple PID control mode, and there are millisecond level delays in tension detection, signal transmission, and motor adjustment, which cannot meet the dynamic adjustment requirements of high-speed production. Under high-speed working conditions, the coil diameter changes in real-time and the motor load inertia fluctuates dynamically. Old control systems cannot achieve precise inertia compensation and adaptive adjustment of taper tension, which easily leads to problems such as loosening and tightening of winding tension before and after, over tension in the early stage, and relaxation in the later stage. At the same time, a single control algorithm cannot counteract the periodic and random composite tension interference, and the wave control accuracy is difficult to meet the precision production standards.

1.4 Dynamic interference of environment and working conditions

        The temperature and humidity fluctuations in the production environment can affect the lubrication effect of the wire surface and the operating status of the equipment transmission components, indirectly causing tension fluctuations; The mechanical vibration generated by high-speed operation of equipment, workshop airflow interference, as well as the start stop switching and load sudden changes during continuous production processes, can all form sudden tension disturbances, disrupting the constant state of wire drawing tension.

2、 Core control technology for tension fluctuation of high-speed precision wire drawing machine

        In response to the multidimensional and composite tension fluctuations in high-speed wire drawing, the mainstream high-precision solution in the industry adopts an integrated control system of "mechanical optimization+sensing detection+algorithm regulation+closed-loop linkage". Through hardware upgrades and software algorithm iterations, real-time monitoring, rapid correction, and precise suppression of tension fluctuations are achieved, and tension deviation is controlled in an extremely low range to meet the needs of high-speed precision production.

2.1 High precision sensing real-time detection system to achieve dynamic monitoring

        Accurate detection is the foundation of tension stability control. The high-speed precision drawing system is equipped with a high-resolution pressure tension sensor, a swing rod position sensor, and an encoder to form a multidimensional detection unit, replacing traditional manual estimation and simple detection modes. The tension sensor collects real-time tension values of the wire in real-time, with a sampling frequency of microseconds, and can accurately capture small tension fluctuations during high-speed operation; The high-precision encoder synchronizes the speed and line speed signals of the tower wheel and winding motor in real time, and monitors the operation status of the wire in real time; The position sensor of the swing rod assists in correcting tension deviation, forming a multi signal fusion detection mechanism, completely solving the problems of tension signal lag and insufficient detection accuracy under high-speed working conditions, and providing accurate data support for subsequent adjustments. Actual test data shows that the detection system can accurately identify small tension fluctuations within ± 0.5%, and fully cover periodic and random tension interference signals.

2.2 Servo vector closed-loop control to eliminate transmission synchronization errors

       The high-speed precision wire drawing machine adopts an independent servo vector drive+fully closed-loop synchronous control architecture. Each wire drawing tower wheel, traction unit, and winding unit is equipped with independent servo motor drive, abandoning the traditional centralized transmission structure. By decoupling the stator current of the motor into excitation and torque components through vector control technology, independent and precise control of speed and torque can be achieved, enabling the AC motor to possess the ultra-high dynamic response characteristics of a DC motor. The control system compares the line speed and tension data of each unit in real time, dynamically adjusts the speed and output torque of each servo motor, and achieves millisecond level synchronous linkage of the entire process of drawing, traction, and winding, completely eliminating tension fluctuations caused by transmission clearance and mechanical inertia. At the same time, the system has a built-in inertia adaptive compensation algorithm that can adjust control parameters in real-time based on changes in winding diameter and load, perfectly solving the problem of tension gradient during high-speed winding. Under the industry's optimal operating conditions, tension fluctuations can be controlled within the optimal range of 5% -15% of wire breakage load.

2.3 Iterative learning+PID composite algorithm to suppress periodic fluctuations

       In response to the periodic tension pulsation caused by mold deviation and mechanical vibration, the high-end wire drawing control system integrates iterative learning control (ILC)+adaptive PID composite algorithm. The iterative learning algorithm can remember the tension error trajectory of the previous production cycle and perform pre compensation in the next production cycle. After 2-3 production cycle iterations, the periodic tension fluctuation amplitude can be attenuated to below 10% of the initial value. The adaptive PID algorithm abandons the traditional fixed parameter adjustment mode and can dynamically adjust the proportional, integral, and derivative parameters based on real-time tension deviation and fluctuation rate, quickly canceling out sudden and random tension disturbances, effectively solving problems such as overshoot, lag, and oscillation in traditional PID adjustment. At the same time, the algorithm integrates a thermal coupling compensation factor, which can adjust the tension setting value in real time according to the temperature changes of the wire, offset the mechanical performance fluctuations caused by temperature, and achieve constant tension control under all working conditions.

2.4 Integrated tension servo drive to reduce signal delay interference

      To solve the communication delay problem caused by traditional PLC multi-level signal transmission, the high-precision tension control system adopts an integrated architecture with a servo driver built-in tension specific algorithm, which directly integrates core algorithms such as roll diameter calculation, taper tension compensation, inertia matching, and error correction into the servo drive unit. Without the need for PLC relay signals, the driver can directly receive feedback signals from tension sensors and encoders, independently complete high-speed calculations and dynamic adjustments, and increase the system response speed to the 200 microsecond level, completely eliminating tension loss caused by signal delay under high-speed conditions. This architecture can adapt to any roll diameter state, maintaining a constant winding tension throughout the entire process, effectively avoiding sudden tension changes when switching between large and small rolls, and ensuring uniform and consistent quality of the entire wire roll.

3、 Assisted wave reduction optimization scheme, stable drawing tension in all directions

        In addition to core electronic control and algorithm regulation technologies, through mechanical structure optimization, process parameter standardization, and equipment maintenance upgrades, external interference can be further weakened, the probability of tension fluctuations can be comprehensively reduced, and a stable control system with software and hardware collaboration can be constructed.

3.1 Precision optimization of mechanical structure

        Precision machining and calibration of the core transmission components of the wire drawing machine, strict control of the roundness and coaxiality accuracy of the tower wheel, traction wheel, and winding reel, and reduction of periodic tension fluctuations caused by inherent errors in the mechanical structure; Using high-precision bearings and gapless transmission components to eliminate transmission clearances and mechanical vibrations; Regularly calibrate and replace wire drawing molds to ensure consistent accuracy and reduce tension pulsation caused by mold deviation from the source. At the same time, optimize the shock absorption structure of the equipment to reduce the interference of high-speed mechanical vibration on wire tension.

3.2 Standardization and Control of Production Processes

       According to the material and diameter specifications of the wire, optimize the ratio of drawing passes and the compression rate of each pass, set the optimal tension range, and the industry standard is to set the tension of the rear pass to 8% -12% of the pulling force of the front pass. At this time, the residual stress of the wire is the most uniform, and the straightness deviation can be controlled within 0.3mm/m. Standardized control of lubrication process, stabilizing emulsion concentration, flow rate, and temperature, ensuring uniform lubrication and cooling during wire drawing process, and avoiding tension fluctuations caused by sudden changes in frictional resistance; Standardize the process of equipment start stop and speed switching, adopt a gradual speed regulation mode, and prevent sudden tension changes caused by sudden speed changes.

3.3 Intelligent monitoring and preventive operation and maintenance

       Equipped with an industrial Internet of Things intelligent monitoring system, real-time recording of tension data, speed parameters, and temperature data throughout the production process, achieving traceability of tension fluctuation data and early warning of abnormalities. By analyzing the tension fluctuation pattern through big data, potential problems such as mold wear, aging of transmission components, and parameter deviation can be predicted in advance, and preventive maintenance can be carried out to avoid sustained tension fluctuations caused by equipment aging and ensure long-term high-speed and stable operation of the equipment.

4、 The Industry Application Value of Tension Stability Control

      The precise control technology for tension fluctuations in high-speed precision wire drawing machines is the core guarantee for achieving high-end and precision production of wire rods, and is of great significance for improving the quality and efficiency of the entire industry. One is to improve product quality. Stable constant tension working conditions can completely eliminate problems such as uneven wire thickness, surface defects, wire breakage, and excessive residual stress, ensuring a high degree of consistency in wire size accuracy, mechanical properties, and appearance quality, meeting the needs of high-end scenarios such as new energy wire harnesses, precision electronic micro wires, and aerospace alloy wires; The second is to reduce production costs, significantly reduce wire breakage and scrap, rework losses of defective products, lower the wear rate of molds and consumables, and improve the continuous production efficiency of equipment; The third is to adapt to the upgrade of intelligent manufacturing. The digital and closed-loop tension control system can seamlessly connect with smart factories and automated production lines, achieve parameter adaptive control, and visualize production data management, and help the wire drawing industry transform and upgrade towards intelligence and high-end.

5、 Summary and Industry Outlook

       The fluctuation of wire tension during high-speed wire drawing is a complex problem that involves the coupling of mechanical, process, control, and environmental factors. A single control method cannot achieve high-precision stability control. The optimal solution in the industry is to build a comprehensive, dynamic, and adaptive constant tension control system based on high-precision sensing detection, servo closed-loop synchronous control as the core, composite intelligent algorithms as the support, and process machinery optimization as the auxiliary, to comprehensively suppress various types of tension wave interference.

       With the continuous iteration of precision manufacturing technology, high-speed wire drawing tension control will develop towards higher response, higher precision, intelligent adaptation, and full process digitization. Through AI algorithm optimization, multi device collaborative linkage, and intelligent compensation for all working conditions, it will further break through the compatibility bottleneck between high speed and high precision, and provide core technical support for the high-quality development of the metal wire precision machining industry.