Modelling of a cast rolling device

Patent metadata

Field	Value
Publication number	US-9764379-B2
Application number	US-201314382129-A
Country	US
Kind code	B2
Filing date	Mar 1, 2013
Priority date	Mar 1, 2012
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A computer determines a thickness and/or a temperature of a metal strip. The computer determines the temperatures occurring along a respective rotation part of the respective surface elements of the rotary elements and a rotary element shape which forms in the region of a draw-off point on the respective surface element, by a respective rotary element model and using an exchanged enthalpy quantity, the respective contact time with a metal and a respective cycle time exchanged per time unit of a respective rotary element of a casting device with the environment thereof. The temperature of the metal situated in the die region, and the heat flow from the metal to the respective surface element, are determined by a respective metallurgical solidification model and using a metal temperature, the temperatures of the surface elements, the rotary element shape and characteristic metal values.

First claim

The invention claimed is:

1. A method for casting a metal strip with a casting device,
wherein the casting device has a die region into which is poured metal having a metal temperature that is greater than a solidus temperature of the metal,
wherein the casting device has at least one rotary element delimiting the die region on one side in each case,
wherein each rotary element has surface elements which move cyclically along a respective rotation path at a respective rotational speed,
wherein the surface elements of each rotary element are immersed at a respective immersion point into metal located in the die region, during further onward movement of the surface elements, the metal solidifies on the surface elements while the surface elements are immersed, to form a respective strand shell, the surface elements terminate contact with the respective strand shell at a draw-off point, the metal strip is withdrawn from the die region at the draw-off point, and the strand shells are constituent parts of the metal strip,
wherein the surface elements of each rotary element require a respective cycle time for a complete revolution along the respective rotation path and require a respective contact time for onward movement from the respective immersion point to the respective draw-off point,
wherein in addition to an enthalpy supply effected per time unit by the metal located in the die region, the rotary elements exchange a respective enthalpy quantity with their environment per time unit, the method comprising:
monitoring a quantity of metal poured into the die region per time unit and the metal temperature of the metal being poured,
ascertaining characteristic values specifying the metal as such, and
for each rotary element, ascertaining the respective cycle time, the respective contact time, and the enthalpy quantity exchanged per time unit by the respective rotary element with its environment;
implementing with a computer a casting model of the casting device, the casting model comprising a strip formation model, as well as a respective rotary element model, and a respective metallurgical solidification model for each rotary element;
calculating by the computer surface element temperatures and rotary element shapes, the surface element temperatures and rotary element shapes determined based at least in part on the respective rotary element model,
the surface element temperatures and rotary element shapes determined based on:
the enthalpy supply effected per time unit by the metal located in the die region,
the enthalpy quantity exchanged per time unit by the respective rotary element with its environment,
the respective cycle time, and
the respective contact time,
the surface element temperatures being temperatures of the respective surface elements resulting in each case along the respective rotation path,
the rotary element shapes being shapes formed on the respective surface elements in a vicinity of the draw-off point;

calculating with the computer a die metal temperature, a heat flow, and a strand shell thickness, the die metal temperature, the heat flow, and the strand shell thickness based at least in part on the respective metallurgical solidification model, the metal temperature of the metal being poured, the surface element temperatures, the rotary element shapes, and the characteristic values specifying the metal as such, the die metal temperature,
determining the heat flow and the strand shell thickness using a respective heat transfer model modeling heat transfer from the die region into the respective surface elements,
wherein the die metal temperature defines a temperature of the metal located in the die region and adjoining the respective surface element, the heat flow defines a heat flow from metal adjoining the respective surface element into the respective surface element, the strand shell thickness depends on the die metal temperature and the heat flow, and the strand shell thickness is determined in conjunction with the rotational speed of the surface elements, the strand shell thickness defining a respective strand shell thickness forming at the draw-off point;
calculating by the computer the thickness of the metal strip and/or the temperature of the metal strip, the thickness of the metal strip being determined making use of the strip formation model to determine the thickness of the metal strip withdrawn from the die region based on the strand shell thicknesses and the rotary element shapes, and the temperature of the metal strip being determined at the draw-off point based on the die metal temperature;
measuring an actual metal strip thickness;
adapting the heat transfer model based on a comparison of the actual metal strip thickness with the calculated metal strip thickness;
outputting from the computer the thickness of the metal strip and/or the temperature of the metal strip; and
comparing the output from the computer to a setpoint and adjusting operation of the casting device toward the setpoint.

2. The method as claimed in claim 1 , wherein the casting model additionally includes a bath model, the computer makes use of the bath model to determine, based on the metal temperature of the metal being poured, for each rotary element, the temperatures of the respective surface elements resulting along the respective rotation path, for each rotary element, the respective rotary element shape in the vicinity of the draw-off point, for each rotary element, the respective enthalpy quantity exchanged per time unit by the respective rotary element with its environment, the characteristic values specifying the metal as such in conjunction with geometric characteristics of the die region, using the heat transfer model, an at least two-dimensionally spatially resolved metal temperature distribution of the metal as a function of location in the die region, and using the metal temperature distribution of the metal, the computer determines the temperature of the metal located in the die region and adjoining the respective surface element.

3. The method as claimed in claim 1 , wherein with the respective rotary element model the computer determines, for each rotary element, based on the enthalpy quantity exchanged per time unit by the respective rotary element with its environment, the respective cycle time, and the respective contact time, a rotary element temperature distribution as a function of location at least in a rotary direction and in a depth direction extending orthogonally to a surface of the surface elements, and the computer determines the rotary element shapes taking into account the rotary element temperature distribution.

4. The method as claimed in claim 1 , wherein the computer determines the respective rotary element shape by integration of the rotary element temperature distribution in the depth direction.

5. The method as claimed in claim 1 , wherein with the respective rotary element model the computer determines not only the heat flow, but also heat contents of the rotary elements themselves.

6. The method as claimed in claim 1 , wherein the heat transfer model is a parameterizable heat transfer model that is spatially resolved at least in a strip width direction.

7. The method as claimed in claim 1 , further comprising measuring an actual temperature of the metal strip withdrawn from the die region, and
adapting the heat transfer model based on a comparison of the actual temperature with the temperature determined by the computer.

8. The method as claimed in claim 1 , wherein the computer is supplied with geometric parameters of the casting device as parameters and the computer takes the geometric parameters into account when determining the thickness and/or the temperature of the metal strip.

Assignees

• Siemens Ag

Inventors

• Dagner Johannes
• Matschullat Thomas
• Winter Guenther

Classifications

• G06N3/126

  Evolutionary algorithms, e.g. genetic algorithms or genetic programming · CPC title

• G06F30/00

  Computer-aided design [CAD] · CPC title

• G06N3/02

  Neural networks · CPC title

• B22D11/0622

  formed by two casting wheels · CPC title

• B22D11/188

  responsive to thickness of solidified shell · CPC title