Solutions for the Global Metals Industry

Slab Sizing Press & Roughing MillThe slab sizing press and roughing mill reduce the widthand thickness of the slab in preparation for the finishingmill. With a large width reduction, the slab sizing presstailors each slab to a particular order. The roughing millmodels provide the target width reduction to the level1 controller, which takes each slab to this desired widththrough a series of press actions. The press is electricallydriven by a large medium voltage motor and drive.Hydraulically driven top and bottom hold down rollsprevent buckling of the slab. Width gauges at the pressentry and at the roughing mill exit validate that the targetwidth is achieved. The entire process is monitored byoperators on HMI screens.Significant Improvements to Operation of the Slab Sizing Press & Roughing MillAdvanced features of the TMEIC system includeimproved caster efficiency, increased mill widthreduction capability, improved width uniformity, andimproved control tolerances. Control features includemicro-tracking (fast tracking) of slab position and speed,performed for the position and pressure regulators.The advanced sizing press model calculations include:• Die gap calculations for the anvil control• Head, body and tail draft calculations for widthreduction• Hold down roll force calculations for buckleprevention• Preforming length calculations for the taperedsections• Table lift calculations to compensate for increasingslab height• Slab elongation ratio and travel time calculationsSlab Sizing PressRoughing MillThe roughing mills (RM) reduce the width and thickness of the bar. They can bereversing, continuous, or a combination of both.Roughing Mill ScreenSlab Tracking RM ModelsControl starts with the level 2 slab tracking function, directing the level 1 sequencingand regulators based on which zone the slab is in. Hot metal detectors and othersensors are used to define the zone transitions. Specific mill references distributedfrom the tracking and set-up models include:• Horizontal roll positions, side guide positions, and RM speeds• Vertical roll positions and draft compensations for the RM edgers• Spray selection for each of the millsDynamic References for Roughing MillAfter leaving the sizing press, the slab travels through the universal roughing millstands where the width is further controlled by the edger drafting. Prior to each pass,the level 2 set-up model provides a new set of references to the mill.Reversing Mill ScreenLooperless Tension Control Between Close Coupled Tandem Roughing StandsClose coupled roughing stands further reduce the width and thickness preparing theslab for the finishing mill stands. Low tension control is applied between the closecoupled stands including coupled edgers.Page 8 of 40© 2011 TMEIC Corporation. All Rights Reserved.