EVFD used in 20-high reversing mill
After the successful operation of Nancal 690V industrial AC drives used for SG-650 4-high reversing mill in a stainless steel plant in Jieyang city, Guangdong province China, Nancal EVFD was successfully applied again in the Sendimir 20-high reversing mill project of another stainless steel plant in Jieyang, with the rated capacity of 6150kW.
This article mainly introduces the application of Nancal EVFD series AC drives used in the 20-high reversing mill project.
Compared with 4-high and 8-high mills, the 20-high mill has better process performance and higher control precision.
In addition, the 20-high mill also has the rolling process of rewinding, which is applied to the final rolling of the coil unevenly wound. During the rewinding operation, the steel requiring rewinding is placed on one side of the coiler and the stable tension is output at the same time. The coiler on the other side runs until all the steel is dragged around a coiler. The main mill does not participate in the whole process of control and drive, rolling diagram is shown as below:
In this project, Nancal EVFD drives a total of 4 motors: 1* 1900kW main rolling motor, 2 *2000kW winding motors and 1* 250kW unwinding motor. The input voltage of the VFD is 690VAC.The rated frequency of the main rolling motor is 18.2hz, the maximum operating frequency is 56.6hz, the rated frequency of the coiler motor is 12.7hz, the maximum operating frequency is 48.2hz, the tension control accuracy is less than 1%, the maximum rolling linear speed is 600m/min, the rated voltage of the motor is 660V, driven by NANCAL common dc bus multi-drives type EVFD., multi-drive rectifier unit adopts AFE front active rectifier, with low harmonic regeneration function. See figure 4 for the system configuration.
||Thickness of left roiling (mm)
||Thickness of right roiling (mm)
||Reduction ratio (%)
||Tension of left roiling (kN)
||Tension of right roiling (kN)
||Roll force (T)
||Speed of main rolling mill (r/min)