Roller coating machine is a key equipment in the production line of color-coated steel strips, and its operation determines the coating thickness and quality, as well as directly affecting the operating rate of the unit. Therefore, it is necessary to choose the most suitable coating equipment and the best coating process to maximize the efficiency of the unit. Roller coating machine is currently the most widely used coating equipment, which has the advantages of flexible process, convenient operation, saving coatings, easy control of coating thickness, etc.
The control of motor speed by frequency converter can be realized in many ways. It can be controlled locally through the buttons on the front panel of the frequency converter, or it can be controlled through the fieldbus, or it can be controlled by the potentiometer analog input on the control panel. The frequency converter controlling the motor of glue roller and coating roller is equipped with a module, which is connected with the fieldbus interface and other transmission systems on the production line to form a fieldbus control system.
The process of frequency conversion motor speed control: the PLC reads the speed value of the transmission device on the production line through the fieldbus, that is, the speed of the steel strip on the production line, and then calculates the speed relationship between the glue roller and coating roller of roller coating machine according to the working principle of two-roller natural reverse rotation. The calculation result is transmitted to the frequency converter through the fieldbus to control the motor speed. However, due to different coatings, different substrates and different requirements for coating thickness, different speed signal values need to be allocated to the glue roller and coating roller. This can be achieved in two ways: first, make a process table in advance, and select a working state in the process table according to the process requirements to allocate process speed to the glue roller and coating roller of the roller coating machine. Second, the speed can be adjusted manually by the potentiometer on the control panel. The signal of the potentiometer on the control panel is also transmitted to the PLC through the fieldbus. The PLC adds the value from the potentiometer to the value previously calculated by the PLC, and sends the final calculation result to the frequency converter to adjust the speed values of the glue roller and coating roller of the coating machine to meet the production process requirements.
The control panel is equipped with a speed table that displays the actual line speed of the coating roller and glue roller of the roller coating machine, and a signal display device for the working state of the glue roller and coating roller is also set up on the control panel.
The roller coating machine adopts a frequency converter speed control system, which meets the production requirements of the process and saves investment. The equipment installation and commissioning are convenient. Since the roller coating machine was put into production and operation, the equipment operation has been stable, and the maintenance workload is small. The equipment production rate has been improved, and good economic benefits have been achieved. The roller coating machine adopts a frequency converter speed control system, and the fieldbus control method can not only meet the requirements of the industrial control system of modern enterprises, but also has stable operation, flexible operation and convenient commissioning.