1. Overview Tentative setting machines are essential finishing equipment in dyeing and printing plants. They are mainly used for stretching and heat setting of pure cotton, polyester-cotton blends, and other blended fabrics, and can also be used for stretching and heat setting of various knitted fabrics. With the development of textile dyeing and printing processes, the market needs high-quality tenter sets to meet process requirements. The annual demand for tenter sets in China's textile industry is around 500 units, and exports have begun. Shaoyang No. 2 Textile Machinery Factory is one of the earliest professional manufacturers of tenter sets in China. To meet the market demand for high-performance tenter sets, the factory developed its eighth-generation product—the M5469 tenter set, which has been successfully exported to countries such as Turkey and Pakistan. [align=center]Figure 1 M5469 Tenter Set[/align] This model of tenter set adopts a modular design and provides a variety of optional parts for different users to process fabrics with different requirements. Its nominal width ranges from 1800 mm to 3600 mm, available for user selection; suitable for various clamp bodies such as needle clamps, fabric clamps, or dual-purpose clamps; applicable to various heat sources such as heat transfer oil, gas, electricity, and steam; nominal speed is 100 m/min; drying chamber temperature control accuracy is ±1% of the set temperature. The fabric feeding area, guide rail section, drying chamber, and fabric dropping area of ​​this machine refer to internationally advanced technologies. Electrically, it adopts internationally popular variable frequency drive, with a synchronous control card from Danfoss company, realizing master-slave chain synchronous position transmission, and its master-slave speed ratio can be arbitrarily set, conveniently achieving different process requirements. Furthermore, PID and feedforward control parameters can be self-tuned, providing convenience for debugging and modification. 2. Process Requirements of the Stenter The complete stenter system includes: fabric feeding and needle (clamp) system; track system; amplitude adjustment system; hot air circulation system; and fabric output system. Electrical control is crucial throughout the entire process and must be considered at all times. In this application, the electrical control system adopts an AC variable frequency speed control system. The main chain is driven by a variable frequency motor, which serves as the master controller for the entire machine. The transmission spline shaft is equipped with a rotary encoder as the speed signal for other following units. The entire system is required to achieve a speed range of 1:10 under constant torque load conditions, with low failure rate, convenient maintenance, simple operation, stable performance, and ideal synchronization. The control system uses a programmable logic controller (PLC), touch screen, frequency converter, and push-button switches to control the entire machine's operation. Moreover, due to process requirements, the precision requirements for the master-slave synchronous control of the entire fabric feeding and output system are extremely high. Comparison of the new solution from Danfoss frequency converters and synchronization cards with traditional solutions: Traditional tenter frame machines use single-axis transmission, which is limited in form and difficult to achieve when a speed ratio is required. Therefore, advanced companies internationally, represented by Germany, have begun to replace traditional single-axis transmission with multi-chain synchronous transmission. Under this trend, Shaoyang No. 2 Textile Machinery, through technical exchanges with Danfoss, finally decided to adopt a solution using Danfoss frequency converters and synchronization cards to implement multi-chain transmission. Danfoss synchronous control has nearly ten years of production application experience, with mature and reliable technology. It is widely used in similar applications, fully meeting the technical requirements proposed by Shaoyang Textile Machinery Company, and provides reliable after-sales maintenance and technical support, allowing users to use it with confidence. Figure 2 shows the actual diagram of its frequency converter control cabinet, and Figure 3 shows the actual operation of the main and slave chains with fabric (load). [align=center] Figure 2: Wiring diagram of the frequency converter; Figure 3: Actual operation with fabric (load)[/align] The basic structure used in this application on the tenter frame is as follows: the main chain is controlled by a separate frequency converter via bus communication; on the slave side, a Danfoss frequency converter with a synchronous control card accurately acquires the encoder signals of the main and slave motors, processes them, and derives the speed and position commands of the slave motor, achieving synchronous control of the main and slave motors. Its control method is simple, the equipment has a high degree of integration, and its operation is reliable. Furthermore, various information commands can be easily fed back to the PLC and touch screen, etc., via the bus, realizing automatic control functions. 3. Precautions for Danfoss Solutions Because stenters extensively use electronic devices such as frequency converters, the electromagnetic interference to the system is very strong. To ensure the normal operation of the synchronization card and frequency converter, users and equipment manufacturers should strictly adhere to certain precautions during equipment installation to avoid unnecessary accidents during later use and save manpower and financial resources. Furthermore, to ensure the system operates at its optimal state, regular and standardized testing can guarantee the synchronization card and frequency converter operate at their best, fully leveraging the advantages of the synchronization card and ensuring the entire system brings maximum benefits to the customer. 4. Application Examples Stenters using synchronization cards have been installed and used in several textile companies in Turkey. The following are actual site photos. The customer is satisfied with the overall system performance, but some malfunctions occurred due to the aforementioned reasons. However, after the customer made improvements according to Danfoss's requirements, satisfactory results were achieved. Representative applications include floor-mounted installation and elevated installation. In elevated installations, raw materials can be stored underneath the equipment, saving space. The following is an example of a floor-mounted installation. [align=center]Figure 4 Floor-mounted installation[/align] 5 Conclusion Thanks to the adoption of Danfoss frequency converters and synchronization cards, the new tenter frame has achieved synchronous speed regulation of AC frequency conversion technology and PLC-controlled frequency converters. This enables precise synchronous control of each master and slave unit and online detection and monitoring of key process parameters, resulting in a qualitative leap in its mechatronics and intelligent capabilities. This makes production more compliant with energy conservation and environmental protection requirements. The successful trial production of the M5469 new tenter frame marks a new starting point for the development of dyeing and printing machinery. It will undoubtedly bring significant economic and social benefits to users and manufacturers, showcasing a bright future for further improving the quality and market competitiveness of China's textiles. Danfoss is honored to be a part of this and hopes to contribute even more in future similar applications and collaborations.