In today’s rapidly evolving and fiercely competitive steel industry, production efficiency and product quality remain the core elements of enterprise competitiveness. Today, we are excited to share a successful case study showcasing how V&T’s V9-H series inverters transformed a 1250 cold roll forming line in a steel mill—demonstrating how this upgrade enabled the production line to achieve a remarkable transformation and embark on a new journey toward high-efficiency manufacturing.

The 1250 cold roll forming line is an automated production system designed for processing steel coils with a maximum width of 1250 mm. Functioning like a precision steel-shaping factory, it continuously forms hot-rolled or cold-rolled steel strips into various profiled sections through a cold roll forming process at ambient temperature. The line integrates multiple coordinated units—including uncoiling and feeding, leveling and shearing, cold forming, cut-to-length, and control systems. Its core principle relies on progressive plastic deformation via multiple roll stands to gradually bend the 1250 mm-wide steel strip into the desired cross-sectional profile. Throughout this process, an automated control system ensures precise speed synchronization among all units, accurate dimensional control, and real-time quality monitoring—guaranteeing consistently high-quality output.

Urgent Need for Retrofit: The “Growing Pains” of an Aging Line
However, as market demands evolve and production pace accelerates, the legacy 1250 cold roll forming line began revealing significant limitations. Mechanical components of the roll stands had aged due to prolonged use, the original inverters were undersized in power rating, and the system operated in open-loop mode using only Modbus RTU (RS485) communication for speed control. These issues led to sluggish mechanical response and poor speed synchronization across the multiple drive shafts of the roll stands. Operators were forced to constantly and manually fine-tune speed ratios between drive axes just to maintain minimal synchronization. This not only imposed heavy labor demands but also severely compromised production speed, output capacity, and product quality—making a comprehensive upgrade imperative.

V&T V9-H Series Inverters: The “Key” to Transformation
To better adapt to changing market conditions and enhance the overall capability of the cold roll forming line, a targeted retrofit of the roll stand drive system was launched—with V&T’s V9-H series inverters playing a pivotal role.

On the mechanical side, motors, gearboxes, and drive shafts of the roll stands underwent thorough inspection and precise realignment. Encoders were added to the motors to enable closed-loop control, significantly improving motor responsiveness and laying a solid mechanical foundation for higher-speed operation.

On the electrical side, modern intelligent control components—including an HMI touchscreen, PLC, and V&T V9-H inverters—were integrated. Specifically, the model V9-H-4T37G/47L-06 was selected for its outstanding performance and reliability, serving as the core of the upgraded system. By adopting PROFINET industrial bus communication, the system now achieves high-speed data exchange and seamless integration among all devices, dramatically enhancing overall coordination and operational efficiency.

At the software level, the production workflow was deeply optimized, and forming process recipes were meticulously refined. The updated control logic now offers operators a more intuitive, simple, and user-friendly interface—greatly reducing operational complexity and the risk of human error.

Results: A Leap in Performance
Following these comprehensive upgrades, the cold roll forming line has been revitalized. Production speed has surged from the original 3 meters per minute to approximately 13.5 meters per minute—the mechanical maximum—delivering a dual leap in both speed and efficiency. This dramatic improvement has not only significantly boosted output but also strengthened the plant’s competitive edge in the marketplace.

In this project, V&T’s V9-H series inverters proved instrumental—leveraging advanced technology and dependable performance to empower the modernization of the 1250 cold roll forming line. Looking ahead, V&T remains committed to innovation, continuous improvement in product quality, and superior customer service—providing premium variable frequency drive solutions to support intelligent, efficient, and sustainable development across industries worldwide.