The printing industry relies heavily on tension control systems to ensure the quality and efficiency of material handling during processes such as unwinding, guiding, and winding. These systems are essential in maintaining consistent tension throughout the production cycle, preventing issues like material deformation, breakage, or poor compaction. A closed-loop tension control system based on STM32L151CCU6 as the main control chip has been developed to address these challenges effectively.
This system utilizes a PID control strategy to achieve high precision and fast response times, making it suitable for various types of printed materials. By calculating the diameter of the material roll in real time, the system ensures that the tension remains optimal throughout the winding process. This is particularly important for soft materials, which can suffer from internal layering if not properly controlled.
Tension control systems are commonly used in light industries, including printing, where maintaining a constant tension is critical. During the winding process, improper tension can lead to either excessive tightness—causing material damage—or looseness, leading to poor product quality. To prevent these issues, the system continuously measures the roll diameter and adjusts the tension accordingly, ensuring smooth and efficient operation.
There are three primary types of tension control systems: indirect, direct, and composite. Indirect methods avoid the need for tension sensors, reducing costs but limiting accuracy. Direct methods, though more expensive, offer higher precision and faster response times. The system described here uses a direct method, leveraging the STM32F103RCT6 microcontroller, which offers high performance, integrated peripherals, and a maximum operating frequency of 72 MHz.
Hardware design includes a signal amplification circuit with an instrumentation amplifier (AD620AN) to ensure accurate measurement of millivolt-level signals from the tension sensor. The system also incorporates optical isolators to interface with angular velocity detectors, which monitor the speed of rollers using proximity or encoder switches. A user-friendly human-machine interface allows for easy input via buttons and encoders, with tension values displayed on an LCD and a digital tube.
The control execution unit is a magnetic powder clutch or brake, depending on whether the process involves winding or unwinding. These devices provide linear torque output based on the excitation current, allowing precise control of the material’s tension. The system uses a constant current module to supply the required voltage and current to the magnetic powder components, ensuring stable and reliable operation.
Overall, this tension control system represents a robust and intelligent solution for the printing industry, combining advanced microcontroller technology with precise control algorithms to deliver consistent and high-quality results.
Shanghai Janetec Electric Co., Ltd. , https://www.janetecelectric.com