In the process of rolling the most significant aspect is the generation of heat through friction and deformation in the roll bite. The most important aspects are:
Because of the current demands on mills to process much lighter exit gages from increased incoming hot strip thickness, much larger reductions are necessary on individual mill stands, such high reductions at a nominal width result in a larger area of contact with corresponding higher rolling force, friction and heat generation.
These high reduction schedules combined with the requirement to produce widening range of material cross-sections with a more diverse range of softer and harder materials also result in increasingly greater challenges in the control of roll temperature and the effective transfer / extraction of heat.
Establishing a uniform homogenous cooling across the rolling width with a uniform and acceptable thermal distribution (no gradients) is the ultimate goal as regards cooling and assures that the universal problem of post cooled shape after recoil is minimized.
A well designed, cooling system in good operating condition will achieve several important objectives:
Symmetrical top and bottom roll cooling arrangements
Roll and coil transverse temperature gradients
Top and bottom spray header in line (parallel) to center lines of work rolls
Roll Cooling Nozzles (PDF)
Selective Roll Cooling Systems (PDF)