US 4,330,263 AGranted

Method of controlling a reheat furnace to control skid mark effects

AssigneeGeneral Electric Company

InventorDonald J. Fapiano

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Abstract

A method for controlling, in a reheat furnace of the type having a heat zone through which metal work pieces are moved over support skids and a soak zone in which slab temperature differentials are reduced, the variations in deformation resistance of the workpiece due to temperature gradients produced by the skids. This method first provides for establishing, for the furnace and the workpiece to be rolled, an initial skid mark characteristic expressing, at the time the workpiece leaves the support skids and enters the soak zone, the ratio of the deformation resistance of the workpiece in a region immediately contiguous the skids to the deformation resistance of the workpiece in a second region which is located approximately mid-way between adjacent skids. A skid mark decay characteristic defining the decay of the skid mark characteristic as a function of time elapsed after the workpiece has left the skids is then established. From the use of the decay characteristic and the initial skid mark characteristic, the time the workpiece should remain in the soak zone in order for the workpiece to achieve satisfactory properties for subsequent rolling operations is determined. Adaptive updating of the skid mark characteristic may be achieved by observing the actual forces occuring during the rolling process. The skid mark characteristic provides an indication of the condition of the support skid insulation and may assist in planning of furnace maintenance.

Claims7

Dependent claims

For use in association with a reheat furnace of the type having at least one heat zone, including support skids over which metal workpieces are moved, and a soak zone in which such workpieces reside for a period of time after leaving the supporting skids of the heat zone prior to being acted upon by a metal rolling mill, a method for controlling said furnace to limit, to acceptable levels, the variations in the deformation resistance of the workpiece during rolling operations due to temperature variations in the workpiece resulting from contact with such skids, said method comprising the steps:

(a) establishing for the furnace and the workpiece an initial skid mark characteristic expressing, at the time the workpiece leaves the supporting skids and enters the soak zone, the anticipated ratio of deformation resistance of the workpiece in at least one first region which was immediately contiguous to a one of the skids to the deformation resistance of a workpiece in a second region which was located approximately mid-way between adjacent skids;
(b) establishing a skid mark decay characteristic defining the decay of said skid mark characteristic as a function of time elapsed after the workpiece has left the skids;
(c) determining from said skid mark characteristic and said decay characteristic, the anticipated ratio of workpiece deformation of said first region to the workpiece deformation resistance of said second region at the expected time of rolling a workpiece;
(d) comparing said anticipated ratio to a predetermined value;
and
(e) adjusting, as necessary, the time period of said workpiece remains in said soak zone based upon the results of said comparison.

3 more elements

Dependencies are inferred from the claim text.