Roll cooling

Optimum roll cooling in hot and cold rolling mills

In the metalworking rolling process in hot and cold rolling mills, heat is generated by friction and deformation in the mechanical forming of the rolling stock. As a result, efficient cooling of the rolls as well as the surrounding roll area is essential for the forming process in order to ensure stable roll temperatures and effective heat conversion or removal. The aim is thus to provide a uniform homogeneous cooling across the roll width with a uniform, acceptable thermal distribution.

Roll cooling

The fundamentals for efficient and economical roll cooling are an optimized nozzle and header arrangement. 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:

  • Maintaining uniform, stable roll temperatures, circumferentially around the roll and transversely across the roll with
  • Creating optimum thermal crowns and minimum differential in temperature in the upper and lower work rolls with optimum heat extraction

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.

Roll CoolingSymetrical top and bottom roll cooling arrangements

Achievement of a uniform homogenous cooling

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

  • Maximum heat extraction at minimal coolant consumption n Symmetrical thermal profiles on the work rolls (minimum gradient in temperature)
  • Controlled thermal crowns
  • “Normal” steady state roll temperatures
  • No differentials in the thermal conditions between the top and bottom work roll
  • Ensure that the roll bending system is kept within range by maintaining the appropriate thermal crown height and symmetry
Roll coolingRoll and coil transverse temperature gradients (left). Top and bottom spray header in line (parallel) to center lines of work rolls (right).

Product overview

Nozzles for roll cooling

Nozzles for roll cooling processes

Whether hot rolling or cold rolling – Lechler offers nozzles and systems to increase quality and efficiency.

More Technical data (pdf, 2.89 MB)
Nozzle systems for roll cooling

Nozzle systems for selective roll cooling processes

Systems and valves for selective roll cooling. The Lechler SELECTOSPRAY system can be operated in conjunction with any of the shape control systems currently available. The nozzle / valve zoning of the SELECTOSPAY system is matching the zoning of the shape roll.

More Technical data (pdf, 3.96 MB)

Further information about roll cooling

Thermal roll cooling studies

Thermal roll cooling studies

For a higher product quality and productivity of a rolling mill, the roll cooling systems are crucial when it comes to process modifications. Lechler here supports you with thermal studies.

Technical data (pdf, 189.70 KB)

Professional reports

Walzenkühlung: General aspects of roll cooling for hot & cold rolling mills
Walzenkühlung: General aspects of roll cooling for hot & cold rolling millsFachbericht aus SEAISI Quarterly Journal (SQJ) 2014, 43, 2; 49-56Hubertus WenigRead now (pdf, 1 MB)
Walzenkühlung: Fundamentals of roll cooling and control of flatness at primary cold reduction
Walzenkühlung: A quantitative study into the comparative efficiency of flat jet and full fone spray nozzles when applied to the application of work roll cooling
Walzenkühlung: Flatness and profile the problems that can exist in the design of the spray actuators
Walzenkühlung: Flatness and profile the problems that can exist in the design of the spray actuatorsContribution paper für The Institute of Materials, Minerals and Mining, Achieving Profile & Flatness in Falt Products, Austin Court, Birmingham (UK), 2006David TuckerRead now (pdf, 904 KB)
Walzenkühlung: Parameters for effictive roll cooling
Walzenkühlung: Parameters for effictive roll coolingConribution paper für Saruc Southern African Roll Users Conference, Emuleni Conference Centre Vanderbijlpark, South AfricaJürgen FrickRead now (pdf, 977 KB)

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