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Mill Special Features

 

Reducing and Sizing Block (RSB) from Kocks Germany
A first in India

Introduction and Process Description RSB

From existing conventional rolling mills, it is difficult to meet the requirements of bars with close tolerances. This can only be met with difficulty and at the expense of loss of efficiency, especially with regard to the loss of mill utilization time and lower yields. At times this is infeasible or cost prohibitive. In conventional roughing and intermediate mills, the tolerance of the finished product is influenced mainly by the variations in the crosssection of the feed material into the finishing section of the mill. The KOCKS 3-Roll Reducing & Sizing Block (RSB), which is ideally suitable for use in Wire Rod and Bar Mill, takes advantage of the special features of the 3-roll technology, in which the spread during deformation is low and the deformation efficiency is high. The Kocks Block is installed in the mill line for the purpose of rolling any desired finished size within the mentioned size range (free-size rolling) to very close tolerances. Thanks to the quick stand changing system and the advanced roll changing and adjustment facility in the roll shop, it is also possible to make extremely fast changes in sections, jumping to and from any size in the mentioned range of finished bar sizes (sequence-free rolling) and thus enabling high flexibility, much shorter delivery lead times for the customer and reduced inventory of rolled product. 

Low Temperature Finishing Rolling Process (LTR)

LTR Process involves a deformation applied in the last passes of the mill, within the
temperature ranges corresponding to Normalising Rolling process or to Thermomechanical
Rolling process. Thus, superior quality product with improved
metallurgical and mechanical properties can be obtained directly at the mill itself
just by operating at lower rolling temperature.

Main features of the LTR system:

Low Temperature rolling is basically a method for on-line control of the final material
properties during the rolling process.
It involves material deformation applied at the last passes of the mill, within the
temperature ranges corresponding to partial re-crystallisation or to suppression of
re-crystallization. As soon as re-crystallization is suppressed, grain refining
phenomena occurs, resulting in improved technological properties of the final
product. In addition, the bar surface quality improves considerably.
The process utilises a series of water cooling boxes installed along the mill, each
followed by temperature re-equalizing zones, governed and controlled by an
advanced process control system.
The distinct advantages are

  • Fine grain size
  • Normalising offline is avoided for carbon steel
  • Improved Low Temperature toughness
  • Better properties after heat treatment for case hardening steels
  • Shorter annealing time for spring steel
  • Improved fatigue strength on the final component
  • Higher tensile strength for micro-alloyed steels achieved directly in-line
  • Reduced decarburizing depth
  • Improved surface quality
  • Resulting straightness of bars =<0.4 mm/m

"Change Free" Rolling

Quick stand changing system reduces the size changing time outside the "free-size" range to 3-5 minutes where it is possible to change from small to bigger sizes and vice versa. Hence this system is known as "Change Free" rolling. Replacement of passes by dummies or the operation of H/V 2-high passes in the intermediate mill for changing the entry section into RSB by modern changing facilities can be accomplished within 5 minutes.

Thus long rolling campaigns can be avoided leading to:

  • shortened delivery lead times
  • reduced work in progress
  • Flexible Rolling strategy