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Lechler Ltd
1 Fell Street, Newhall
Sheffield, S9 2TP, England
Tel: +44(0)114 249 2020
info@lechler.com
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SELECTOSPRAY® Selective Roll Cooling Systems

SELECTOSPRAY® Selective Roll Cooling Systems

SELECTOSPRAY® Selective Roll Cooling Systems Meet the Process Challenge

Benefits:

  • Dynamically controls heat transfer into the roll surface, generated by deformation / friction in the roll bite
  • Significantly improves strip flatness and counteracts asymmetric "shape" deviations
  • Maintains optimum work roll and strip surface quality
  • Reduces work roll surface deterioration and wear
  • Promotes and sustains stable roll coating in specific Cold Rolling and Hot Rolling applications
  • Facilitates a significantly wider operating range for other actuators and contributes to extended work roll campaigns and consequent work roll life 
  • Reduces applied volumes through more efficient application and improves recovery costs of coolant and lubrication


Details:


In the rolling process the generation of heat through friction and deformation in the roll bite, presents the principle challenge in achieving optimum rolling performance.

Because of the ever changing  demands on rolling mills to produce much lighter exit gauges from increasingly thicker  hot strip input, much greater reductions are required on individual mill stands.

Such higher reductions at a nominal width result in a larger area of contact between the work rolls and the strip with correspondingly higher rolling forces, friction and heat generation and heat transfer into the rolls.

These high reduction schedules combined with the requirement to produce a 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 in the roll stack.

The frictional / deformation heat  is partially absorbed by the work rolls in varying degrees based on the reduction / drafting  pattern which  causes localised, irregular and variable thermal expansion of the work rolls.

The changing profile of the work rolls is transferred to the strip and if not selectively controlled (cooled) results in out of shape, non-flat sheet being produced with wavy edges and buckles ("bad shape").

Establishing uniform homogenous cooling across the roll with a uniform and acceptable thermal distribution transversely across the work roll, without uncontrolled thermal profiles or asymmetrical gradients, is the ultimate goal in terms of cooling, to assure:

  • Flat strip at the recoiling stage
  • Avoidance of the post-cooled shape after recoil when the  rewound finished coil cools.


The most important considerations in production are:

  • Maintaining uniform, stable roll temperatures
    • Circumferentially around the work-roll.
    • Transversely across the work-rolls.
  • Maintaining optimum  thermal crowns
  • Maintaining minimum differential in temperature profiles in the upper and lower work rolls.
  • Achievement of optimum heat extraction.