In the cable manufacturing industry, the stranding process is a core step that determines cable performance, and its tension control accuracy directly affects the cable's mechanical strength, electrical performance, and signal transmission stability. With the development of communication technology and power systems towards higher frequencies and higher voltages, the requirements for cable stranding quality are becoming increasingly stringent, and traditional tension control methods are no longer sufficient to meet the demands of precision stranding. Tension sensors, with their ability to accurately measure wire tension, play a crucial role in the stranding process, becoming an important technical support for ensuring the quality and performance of cable products.
Tension sensors operate on the principle of precise conversion of physical effects, with strain gauge tension sensors being the most common and widely used. Their core structure includes an elastic element, a strain gauge, and a signal processing circuit. When wire tension acts on the elastic element, the element undergoes a slight deformation. The attached strain gauge changes its resistance value with this deformation, which is converted into a voltage signal via a Wheatstone bridge. After amplification and filtering, the output signal is an electrical signal proportional to the tension, achieving precise tension measurement. Different types of tension sensors vary in measurement range and accuracy, but all aim to provide reliable tension data for the stranding process. Their measurement accuracy can reach ±0.5% FS, with response time controlled in milliseconds, making them suitable for the high-speed stranding conditions in cable manufacturing.
From a type perspective, tension sensors are mainly divided into strain gauge type and micro-displacement type. Strain gauge type uses a tension strain gauge and a compression strain gauge connected in a specific bridge configuration; the change in resistance under external force is proportional to the magnitude of the tension. Micro-displacement type utilizes external force to cause displacement of a leaf spring, and detects the tension through a differential transformer; it is named for its extremely small leaf spring displacement (approximately ±200μm). Structurally, they can be categorized into shaft-mounted, through-shaft, and cantilever types to adapt to the installation requirements of different cable equipment such as stranding machines and cable bundling machines.
In power cable stranding applications, the application of tension sensors significantly improves the mechanical properties of the cables. Taking high-voltage cable stranding as an example, multiple copper core wires need to be stranded with uniform tension. Inconsistent tension leads to uneven stress distribution within the cable, affecting its bending resistance and current-carrying capacity. Tension sensors are installed in each pay-off unit of the stranding machine to monitor the tension changes of each core wire in real time. When the tension of a core wire deviates from the preset range (e.g., the stranding tension of 10kV cable copper cores is typically controlled at 20-30N, with an error ≤ ±1N), the sensor feeds back the signal to the control system, which automatically adjusts the braking torque of the corresponding pay-off reel to ensure consistent tension in all core wires during stranding. After introducing this technology, a cable manufacturer saw its high-voltage cable stranding uniformity pass rate increase from 85% to 97%, and the number of breaks in cable bending tests significantly decreased, effectively improving the cable's service life.
The stranding process of optical cables also relies heavily on the precise control of tension sensors. During stranding, the fiber bundles and reinforcing cores must be stranded under stable tension. Tension fluctuations increase fiber microbending loss, affecting signal transmission quality. Tension sensors are distributed along each fiber path in the stranding machine, monitoring the tension of each fiber bundle in real time. When the tension is abnormal (e.g., a deviation exceeding ±0.3N), the system automatically adjusts the pressure of the tension adjustment wheel to ensure tight stranding and uniform tension. After implementing tension sensors, a certain optical cable manufacturer saw a 40% reduction in fiber loss and a significant improvement in signal transmission stability, meeting the stringent performance requirements of high-speed communication networks.
Tension sensors also play a crucial role in the stranding process of specialty cables. Aerospace cables have extremely high requirements for vibration resistance and tensile strength; improper strand tension control can lead to a loose cable structure, affecting its reliability in complex environments. Tension sensors monitor the dynamic tension during the stranding process in real time and automatically adjust tension parameters according to the performance requirements of the specialty cables, ensuring a tight stranded structure and uniform tension. After adopting this technology, a specialty cable manufacturer increased the vibration resistance test pass rate of its aerospace cables to 99%, effectively ensuring the stability of its products in extreme environments.
Currently, tension sensors are widely used in the stranding process of the cable manufacturing industry, offering advantages such as high measurement accuracy and fast response speed, effectively meeting the control requirements of stranding tension for different types of cables. Looking ahead, as cable manufacturing moves towards intelligence and high precision, tension sensors will evolve towards higher integration and intelligence. On one hand, sensors will be deeply integrated with the Industrial Internet and big data analytics to achieve real-time acquisition and cloud analysis of stranding tension data, providing data support for cable process optimization and quality traceability. On the other hand, by developing new sensitive materials and adaptive control algorithms, the adaptability of sensors to different materials and specifications of wires will be further improved, driving the cable stranding process towards greater intelligence and precision, and continuously playing a vital role in improving the performance and reliability of cable products.
