Abstract : In the strip steel color coating production line, the roller coater adopts frequency converter speed control. The frequency converter is connected to the PLC control equipment through the PROUFIBUS fieldbus to form a communication network control system, realizing the process operation and speed control of the roller coater. Due to the use of network control, the roller coater can adjust the speed of each roller in real time according to the overall production status to ensure the coating quality of the strip steel surface. Keywords : Frequency converter; Roller coater; PROUFIBUS 1 Overview The roller coater is a key piece of equipment in the strip steel color coating production line. Its operation determines the coating thickness and coating quality, and directly affects the machine's operating rate. Therefore, it is essential to correctly select the most suitable coating equipment and the optimal coating process to maximize the unit's efficiency. The roller coater is currently the most widely used coating equipment, with advantages such as flexible process, convenient operation, paint saving, and easy control of coating thickness. Roller coating machines are generally named according to the coating method, such as two-roller roller coating machines, three-roller roller coating machines, forward roller coating machines, reverse roller coating machines, etc. There are many basic types of roller coating methods. Different roller coating methods can be used on the same roller coating machine, mainly depending on the process conditions. The most commonly used roller coating methods are natural roller coating, natural reverse roller coating, and full reverse roller coating. To meet the needs of various coating materials, coating thicknesses, and different substrates, and to ensure the different speed ratios between the rollers and the strip steel required by the process, currently, each coating roller of the roller coating machine is driven independently. In the 1250mm wide strip steel color coating production line unit of Southern Steel Company, the roller coating machine currently used is a two-roller roller coating machine, and the roller coating method adopted is the two-roller natural reverse roller coating method. 2. Working Principle of Two-Roller Natural Reverse Roll Coating Method As shown in Figure 1, the working principle of the two-roller natural reverse roller coating method is: the rotation direction of the coating roller is opposite to the running direction of the strip, and the rotation direction of the material roller is opposite to the rotation direction of the coating roller. The thickness of the steel sheet coating is controlled by changing the relative speed and gap (extrusion pressure) of each roller. With a fixed gap between rollers, the speed of the coating roller must change according to the speed of the support roller, i.e., the running speed of the steel strip (unit). Assuming the unit running speed is 100%, the speed of the coating roller is typically 50%–150% of the strip running speed, and the speed of the adhesive roller is approximately 20%–60% of the strip running speed. However, due to different coatings, different substrates, and different coating thickness requirements, the speed of each roller sometimes needs to be determined based on the production process. This is determined by the characteristics of the coating process itself. To address this characteristic, we selected a variable frequency drive for the coating roller drive device and used network communication for process operation and speed control. In practical applications, this system is easy to operate and can meet the speed requirements of each working roller for different processes, greatly saving equipment costs and production costs. [b][align=center]For more details, please click: Application of Variable Frequency Speed ​​Regulation in Steel Strip Color Coating Production Line[/align][/b]