6-High Rolling Mills
Six-high rolling mills are the similar to 4-high rolling mills however, they have work rolls, intermediate rolls, and back up rolls. Refer to Drawings (right), which shows a 6-high reversing mill for rolling light gauge steel. The intermediate rolls can be adjusted horizontally to prevent edge drop, which means the edge become lighter in thickness because there is no support at the edge. The rolls can be ground to an hourglass shape. A 6-high mill also allows for substantial roll shape, depending upon the horizontal movement of the rolls. Another advantage of a 6-high mill is a larger work roll which can transmit considerable torque and allow for high speeds up to 7,000 FPM. Large diameter, light gauge coils can have thousands of lineal feet, and unless the speeds are substantial, (4,000 to 7,000 FPM), the cost of making the material is substantial. Also, the larger rolls allow for heat transfer so the temperature is held with or without thermal change at these high speeds. Roll bend can also be provided in a 6-high mill. These mills can be pinion stand or dual motor driven. Six-high rolling mills are equipped with hydraulic screwdowns, automatic shape control, and automatic gauge control.
