Method and device for optimizing the cooling capacity of a continuous casting mold for liquid metals, particularly for liquid steel

Abstract

The invention relates to a method for optimizing the cooling capacity of a continuous casting mold ( 1 ) for liquid metals, particularly for liquid steel, by homogenizing the thermal load ( 22 ) above the height of the continuous casting mold ( 1 ). According to the method, the cooling medium ( 5 ) is guided through a cross-sectional area of a large number of cooling medium channels ( 3 ) or cooling medium boreholes ( 4 ) running approximately parallel to the cast billet ( 9 ). The cooling medium cross-sectional areas between the mold entry ( 6 ) and the mold exit ( 7 ) are configured differently. In order to homogenize the thermal mold load ( 22 ), a smaller cross-sectional area sets the flow rate of the cooling medium ( 5 ), which is conducted from the top downward, inside the cooling medium channel ( 3 ) or inside the cooling medium borehole ( 4 ) higher in the upper area of the continuous casting mold ( 1 ) than in the lower area of the continuous casting mold ( 1 ) in which the flow rate is set lower by a larger cross-sectional area and/or the covering of the cooling medium is adjusted by a cross-sectional shape that varies from the top downward.

1 . A method of optimizing the cooling capacity of a continuous casting mold for liquid metal, especially for liquid steel by homogenizing the thermal load over the height of the continuous casting mold in which the coolant is passed through a cross sectional area of a large number of coolant channels or coolant bores which run generally parallel to the cast strand, whereby the coolant cross section between the mold inlet and the mold outlet is configured differently, characterized in that the flow cross section of the coolant which is passed through the continuous casting mold from the top to the bottom, is set to be higher in the coolant channels or coolant bores of the upper region of the continuous casting mold as a result of a smaller cross sectional area than in the lower region of the continuous casting mold in which the flow velocity is adjusted to be less than a greater cross sectional area and/or in that the coverage with coolant has a cross sectional shape which varies from the top to the bottom.  
     
     
         2 . The method according to  claim 1 , characterized in that at a casting speed of 3 m/min to about 12 m/min a heat flow loading of the continuous casting mold of a maximum of 8 MW/m 2  and a coolant speed of 4 m/s to 30 m/s is maintained.  
     
     
         3 . The method according to  claim 1 , characterized in that a maximum thermal loading of the mold plates at their hot side is less than 550° C. and that the heat transfer coefficient α is set up to 250,000 W/m 2 ·K.  
     
     
         4 . The method according to  claim 1 , characterized in that the continuous casting mold is oscillated.  
     
     
         5 . The method according to  claim 1 , characterized in that the cast strand is lubricated with casting powder slag in the continuous casting mold.  
     
     
         6 . The method according to  claim 1 , characterized in that the surface of the cooling channels is provided with increased roughness from mold inlet to mold outlet.  
     
     
         7 . An apparatus for optimizing the cooling capacity of a continuous casting mold for liquid metal, especially for liquid steel by homogenizing the thermal load over the height of the continuous casting mold in which the coolant is passed through a cross sectional area of a large number of coolant channels or coolant bores which run generally parallel to the cast strand, whereby the coolant cross section between the mold inlet and the mold outlet is configured differently, characterized in that the coolant channels ( 3 ) or the coolant bores ( 4 ) respectively have a relatively small coolant channel inlet cross section ( 14 ) and a greater outlet cross section from the mold inlet ( 6 ) to the mold outlet ( 7 ) with a greater coverage of the mold inlet ( 6 ) by the coolant ( 5 ).  
     
     
         8 . The apparatus according to  claim 7 , characterized in that the variation of the cross sectional shape from mold inlet ( 6 ) to the mold outlet ( 7 ) is continuous.  
     
     
         9 . The apparatus according to  claim 7 , characterized in that the casting speed in the continuous casting direction is adjustable up to about 12 m/min.  
     
     
         10 . The apparatus according to  claim 7 , characterized in that a thermal loading ( 11 ) of the continuous casting mold ( 1 ) of a maximum of 8 MW/m 2 , a coolant speed ( 16 ) of 4 to 30 m/s and a maximum local thermal loading ( 11 ) of the copper plates ( 2 ) on the liquid metal side ( 11 . 1 ) are provided with a heating transfer coefficient α of a maximum of 250,000 W/m 2 ·K.  
     
     
         11 . The apparatus according to  claim 7 , characterized in that the coolant channels ( 3 ) have rectangular cross sections and increase in the channel depths ( 3 . 1 ) and/or channel widths ( 3 . 2 ) from mold inlet ( 6 ) to mold outlet ( 7 ).  
     
     
         12 . The apparatus according to  claim 7 , characterized in that the cross sectional areas ( 19 ) of the cooling channels ( 3 ) are variable by means of baffles ( 3 . 3 ) through a control or regulation ( 3 . 3 . 1 ).  
     
     
         13 . The apparatus according to  claim 7 , characterized in that the surface of the coolant channels ( 3 ) are provided with a roughness ( 21 ) from the mold outlet ( 7 ) to the mold inlet ( 6 ).  
     
     
         14 . The apparatus according to  claim 7 , characterized in that the roughness ( 21 ) is formed by pits ( 24 ) of 0.5 to 3 mm diameter and 0.5 to 2 mm depth.  
     
     
         15 . The apparatus according to  claim 7 , characterized in that the distribution or the number of pits ( 24 ) increases from the mold outlet ( 7 ) to the mold inlet ( 6 ).  
     
     
         16 . The apparatus according to  claim 13 , characterized in that the roughness ( 21 ) is variable by chemical or mechanical features.  
     
     
         17 . The apparatus according to  claim 16 , characterized in that the roughness ( 21 ) is variable during the casting process.