Extrusion die for liquid metals, in particular for liquid

Abstract

An extrusion die ( 1 ) for the casting of liquid metals, in particular of liquid steel materials, has a heat flow density which is distributed non-homogenously over the die face. A homogenizing of the heat flow density can be obtained if the spacing between the hot side and the cooling duct base (=thickness ( 6 ) of the die wide side plate ( 2 )) in the new state as a typical normal thickness (100%) is reduced by at least 20% to 80%, and a further reduction, obtained by means of reworking processes, of the thickness ( 6 ) which is initially reduced to 80% is restricted to 5 mm a final thickness ( 6 a ) by means of a final reworking process.

1 . A continuous-casting mold for molten metals, in particular, for molten steel, comprising mold side plates surrounded by water boxes for the circulation of coolant, the plates defining a mold cavity with a parallel and/or curved path, and mold end plates composed of copper alloy, on the outer face of which a plurality of coolant passages are provided that at a region of the upper melt surface have a minimum coolant-passage flow cross-section with a thickness reduction of the respective mold side plate, wherein a spacing between the hot face and the coolant passage base of the mold side plate in the new state as the conventional normal thickness is reduced by at least 20% down to 80%, and a further reduction, resulting from resurfacings, of the thickness initially reduced to 80% is limited to an approximately 5 mm final thickness by a final resurfacing. 
   
   
       2 . The continuous-casting mold according to  claim 1  wherein the coolant-passage flow cross-section at the upper melt surface is reduced proportionally to the reduction in the thickness of the mold side plate. 
   
   
       3 . The continuous-casting mold according to  claim 2  wherein the coolant-passage flow cross-section is reduced not more than 80% of the new state of the initial coolant-passage flow cross-section. 
   
   
       4 . The continuous-casting mold according to  claim 1  wherein both the reduction in the thickness of the mold side plates as well as the reduction in the coolant-passage flow cross-section is a function of positions of the given coolant passage in the width direction. 
   
   
       5 . The continuous-casting mold according to  claim 1  wherein the mold side plate is reduced in thickness between 5 mm and 10 mm up to a maximum of 15 mm in 3-10 resurfacings, wherein a single resurfacing consists in removing approximately 0.3 mm to 1.5, at maximum 3 mm, of copper material. 
   
   
       6 . The continuous-casting mold according to  claim 1  wherein the coolant-passage flow cross-section at the upper melt surface and down to the mold outlet in each case consists of a filler piece attached on the outer face and composed of normal-temperature-resistant material. 
   
   
       7 . The continuous-casting mold according to  claim 6  wherein the filler piece is adjustable at least in order to reduce the coolant-passage flow cross-section. 
   
   
       8 . The continuous-casting mold according to  claim 1  wherein at least the mold side plates are designed as cassette plates that in expandable form rest on the outer face on cooled adapter plates. 
   
   
       9 . The continuous-casting mold according to  claim 8  wherein a separate displacement body is provided on the adapter plate to create the minimum coolant-passage flow cross-section. 
   
   
       10 . The continuous-casting mold according to  claim 8  wherein the displacement body is designed having different shapes, is stored, and attached so as to be replaceable. 
   
   
       11 . A continuous-casting mold into which molten steel is poured and converted into a strand, the mold comprising:
 a pair of upright and horizontally spaced side walls having outer cold faces turned away from each other and confronting inner hot faces;   a pair of end walls bridging the side walls and forming therewith an upwardly open mold cavity in which the molten metal has an upper melt surface; and   a respective structure forming with each of the cold faces a respective array of passages extending past a region adjacent the upper melt surface, each passage being of reduced flow cross section in a region adjacent the upper melt surface, each passage lying below the region outward at a predetermined horizontal spacing from the respective hot face, each passage further lying at the region at a closer spacing equal to at least 5 mm and between 20% and 80% of the predetermined spacing below the region.   
   
   
       12 . The continuous-casting mold defined in  claim 11  further comprising
 means for pouring molten steel into the cavity such that the steel forms in the cavity a melt having the upper melt surface.   
   
   
       13 . The continuous-casting mold defined in claim wherein the reduction in flow cross section of the passages at the region is proportional to the reduction in the spacing. 
   
   
       14 . The continuous-casting mold defined in  claim 11  wherein the passages are spaced horizontally in each side plate and reduction in flow cross section varies outward from a central location in the respective side plate. 
   
   
       15 . The continuous-casting mold defined in  claim 11  wherein the structure is a separate plate fitted to the respective cold face.