Browse Prior Art Database

Controlling of a Multistrand Continuous Casting Machine

IP.com Disclosure Number: IPCOM000079461D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 62K

Publishing Venue

IBM

Related People

Pellinat, WK: AUTHOR

Abstract

In a multistrand continuous casting machine, molten metal flows from a ladle 1 into a tundish 2 and from the tundish through discharge nozzles 3 into water cooled open-ended molds 4. The solidifying strands of metal 5 are withdrawn from the associated mold by pinch rolls 6. After passing through sets of bendor rolls 7 the strands move through straightening rolls 8 to utilization devices 9, e.g., for cutting the strands into predetermined lengths. In the past, the height of the molten metal in the mold was generally controlled by varying the speed of the pinch rolls 6 withdrawing the cast strand from the mold, and by adjusting the rate at which molten metal is supplied to the mold.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 3

Controlling of a Multistrand Continuous Casting Machine

In a multistrand continuous casting machine, molten metal flows from a ladle 1 into a tundish 2 and from the tundish through discharge nozzles 3 into water cooled open-ended molds 4. The solidifying strands of metal 5 are withdrawn from the associated mold by pinch rolls 6. After passing through sets of bendor rolls 7 the strands move through straightening rolls 8 to utilization devices 9, e.g., for cutting the strands into predetermined lengths. In the past, the height of the molten metal in the mold was generally controlled by varying the speed of the pinch rolls 6 withdrawing the cast strand from the mold, and by adjusting the rate at which molten metal is supplied to the mold.

In this controlling scheme, the molten metal flows unpredictably and at different rates from the uncontrolled tundish discharge nozzles 3 to the molds. In order to maximize throughput consistent with good quality, the fastest or leading strand is identified, and the set of associated pinch rolls 6 are operated at a constant predetermined casting speed. This speed is calculated as the maximum allowable reference speed via a heat transfer model, or is looked-up from stored tables representing standard casting practice alternatives. When reference speeds are computed, limiting control parameters, such as minimum allowable shell thickness, minimum allowable strand surface temperature, and maximum allowable crater depth, which is the physical location of the end point of solidification, are all taken into account together with the actual measurements of the prime variables, such as temperatures, machine speeds and spray water flow rates.

The mold level of the mold associated with the leading strand 5 is maintained at a predetermined height, by manipulating the metal pour rate from ladle 1 into tundish 2 as the position of the ladle pouring device 10 is varied. The mold levels for the remaining strands 5 are maintained at predetermined heights by varying the speeds of the associated sets of pinch rolls 6, with the aid of properly controlled motors 11.

Whenever a new leading strand is identified by determining the largest relative error among all of the strands, the manipulated variable for that strand, i.e., the casting speed, becomes...