Coating machines are mainly used for surface coating production of films, paper, and other rolled substrates. These machines coat the substrate with a layer of glue, paint, or ink with specific functions, and then rewind it after drying. With a special multifunctional coating head, they can realize various forms of surface coating.
Shenzhen KEVAN Drive Technology Co., Ltd., a professional VFD manufacturer and industrial inverter supplier, offers the KV600 series inverter as a proven solution for coating machine applications. The rewinding and unwinding sections are equipped with full-speed automatic film splicing mechanisms and PLC program tension closed-loop automatic control.
Coating Machine Process Requirements
The coating machine system steps are generally divided into three stages: constant tension unwinding, multi-level synchronous control of the coating process, and constant tension winding.
During normal production, the substrate tension must remain constant, the line speed constant, and both startup and shutdown processes must be smooth. Therefore, the key to controlling the electromechanical performance of a coating machine is tension control. The tension level directly affects product quality and quantity:
- If tension is too high, it damages the physical properties of the coated paper, affecting service life and quality
- If tension is too low, winding becomes too loose and paper feeding unstable, affecting subsequent processes
Throughout the entire process — whether during startup acceleration or shutdown deceleration — constant speed operation at any line speed requires that the coating roller, compounding roller, and traction roller maintain synchronized running line speeds. Otherwise, abnormalities such as paper breakage, winding displacement, aluminum foil wrinkling, or printing cracks will occur. In this process, the composite coating motor requires:
- Fast speed response
- Accurate speed control
- Small tension fluctuations
KV600 Inverter Solution for Coating Machines
Transmission tension control is achieved by maintaining constant linear speed in the control system. Currently, the industry primarily uses high-quality PLCs for constant linear speed control. However, traditional PLC-based solutions have limitations: a large number of A/D and D/A modules are required, and the PLC’s operational speed and signal transmission can slow the system’s dynamic response.
Therefore, high-quality vector inverters with high-resolution analog inputs, fast dynamic response, and high speed stabilization accuracy are needed to compensate for delays. The KV600 inverter from KEVAN provides an optimized solution.
1. Unwinding Stage – Constant Tension Control
The KV600 series inverter maintains constant substrate tension using automatic PID closed-loop control. The pay-off speed changes closely with the take-up speed. When the wire becomes loose, the take-up speed adjusts accordingly. When a wire breaks, the pay-off reel stops immediately. Since the pay-off reel has a brake device, the inverter is set to free stop, and the entire unwinding process runs independently.
2. Coating and Drying Stages – Multi-Level Synchronous Control
The coating and drying stages require multiple open-loop vector control inverters using proportional linkage control. During coating machine production, the main signal and fine-tuning signal operate in superposition. Line speed synchronization is achieved by superimposing the main frequency and auxiliary frequency.
To achieve line speed synchronization across multiple stages:
- The main frequency of the first inverter is transmitted to the second via RS485 communication
- This continues to the last inverter
- Transmitting operating frequency via communication prevents attenuation of analog signals during transmission
- The auxiliary frequency of each inverter is the fine-tuning frequency, with accuracy as high as 0.01Hz
3. Winding Stage – Constant Tension Control
A KV600 tension control inverter is used for the finished product winding stage. It maintains constant tension using open-loop control and automatically calculates taper and roll diameter. No external tension device is required. It tracks the winding stage of the finished product produced by the coating machine.
Conclusion: KV600 Coating Machine Solution Results
The coating machine system implemented with the KV600 inverter is stable and reliable throughout the entire operation process, delivering excellent economic benefits. After actual production testing, customers are very satisfied with the KV600 overall solution.
Key Advantages of the KV600 Coating Machine Solution
- Simplified control architecture – Constant tension control and synchronous control are both completed by the frequency converter, without the need for an external controller. The electronic control system uses PLC control with a simple structure.
- Precise constant tension control – Tension during production is very constant with high control accuracy. The substrate is not damaged, coating effect is uniform, and product quality is excellent. The on-site environment is clean with no oil leakage.
- Superior winding tension management – Through winding taper compensation adjustment, the winding tension of the finished product remains constant, completely avoiding the common problem of “tight inside, loose outside”.
- Mature technology – Very convenient for commissioning, operation, and maintenance.
Why Choose KEVAN KV600 for Coating Machine Applications
The KV600 series inverter offers features specifically tailored for coating machine applications:
- Built-in PID closed-loop control for precise tension management
- RS485 communication for lossless frequency transmission
- Fine-tuning frequency accuracy up to 0.01Hz
- Open-loop vector control for multi-stage synchronization
- Taper and roll diameter automatic calculation
- Fast dynamic response and high speed stabilization accuracy
Contact KEVAN Overseas Sales
For more information about the KV600 inverter for coating machine applications, or to discuss your specific requirements, please contact our overseas sales team:
Overseas Sales Contact: Mr. Li
Phone: +86-13725501611
Email: Service@kevaninverter.com
Company Address:
Room 501, Building 11, Nangang Second Industrial Park
No. 1026, Songbai Road, Sunshine Community, Xili Street
Nanshan District, Shenzhen, China
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