Patent Publication Number: US-2015068700-A1

Title: Casting Wheel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is the U.S. national stage of International Application No. PCT/DE2013/000095 filed on Feb. 22, 2013 which claims priority from German patent application serial no. DE 10 2012 007 312.7 filed on Apr. 13, 2012, the entire contents of both of which are hereby expressly incorporated by reference into the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a casting wheel for manufacturing strands of metal or metal alloys. 
     2. Description of Related Art 
     A casting wheel has a peripheral casting channel that is outwardly bounded by a circulating band over a partial periphery of the casting wheel. The band is made of steel. The casting channel is cooled by the spraying on of a cooling fluid, in particular water. Such casting wheels are used in wire manufacturing, for example, in the casting of liquid non-ferrous metal, such as copper or aluminum, respectively copper alloys or aluminum alloys, into strands. Wires are then fabricated from the strands in subsequent forming processes. 
     The casting wheel rotates about the central axis of rotation thereof; the endlessly circulating steel band covering the casting channel over an area that corresponds to approximately three quarters of the peripheral length thereof. Thus, a U-shaped channel, which is open to the top at both ends, is formed by the casting channel and the band. Liquid non-ferrous metal is poured into the one end. The non-ferrous metal introduced into the casting channel solidifies at the outer surface during a one half to three-quarter rotation of the casting wheel, to then leave the casting channel at the other end as a strand. 
     Due to the rotation of the casting mold, another peripheral region of the casting channel comes continuously in contact with the liquid non-ferrous metal. This factual situation leads to a permanent thermal cycling and, in the worst case, to premature crack formation. 
     Today&#39;s casting wheels are typically designed to have a mold bottom thickness, i.e., a region underneath the casting channel of approximately 40 mm. Effectively, however, only a mold bottom thickness of 20 mm is required, so that cracks that have formed in the casting channel can be removed by repeated machining, i.e., by lathing. Depending on the machining operation, lathing is typically carried out to a thickness of approximately 2 to 5 mm. 
     To improve the dissipation of heat, it is known to reduce the mold bottom thickness from the outset to approximately 20 mm. However, the drawback resides in that, once cracks form, it is no longer possible to postmachine the casting wheel. 
     The same problem was encountered when working with casting wheels that did, in fact, have a larger mold bottom thickness, into which deep cooling grooves had been milled to improve heat dissipation. The depth of the cooling grooves obviated the need for a remachining because a minimum thickness of 20 mm was fallen short of. 
     Another problem is that deposits form because of the often inadequately filtered cooling fluid, typically cooling water, and because of the evaporation of the cooling water on the hot surface of the casting wheel. As they increase in thickness, these deposits increasingly reduce the dissipation of heat. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a casting wheel that will permit substantial heat dissipation, and, moreover, that will also permit a repeated postmachining of the casting channel. 
     This and other objects of the invention which will become apparent from the detailed description of the invention which follows are achieved by a casting wheel for manufacturing strands of metals or metal alloys comprising a peripheral casting channel ( 2 ) that is bounded over a partial length by a circulating band ( 11 ); below the casting channel ( 2 ), a mold bottom ( 3 ) being provided for being cooled with a cooling fluid, wherein the inner side ( 7 ) of the mold bottom ( 3 ) facing away from the casting channel ( 2 ) is provided with a profiling ( 6 ) that has a profile height of 0.5 to 6 mm. Preferred embodiments and refinements of the invention will also be described in the following detailed description of the invention in conjunction with the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  schematically shows a cross section through a casting wheel  1  of which only one casting channel is shown due to the axially symmetric configuration. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The casting wheel according to the present invention for manufacturing strands of metals or metal alloys includes a peripheral casting channel that is bounded over a partial length by a circulating band. Below the casting channel, a mold bottom is provided for being cooled with a cooling fluid. The inner side of the mold bottom facing away from the casting channel is provided in accordance with the present invention with a profiling that has a profile height of only 0.5 to 6 mm; in particular, the profile height is within a range of from 0.5 to 3 mm. The profiling preferably has a profile height of 2 mm at a maximum. 
     On the one hand, such a low profile height makes it possible to significantly improve the cooling of the casting wheel since the surface, that the cooling fluid comes in contact with, is considerably enlarged. On the other hand, the profiling is so low, due to the limited height thereof, that the casting wheel may be lathed several times, making it possible for either the mold bottom thickness to be reduced, which, in turn, leads to an improved heat dissipation; or, on the other hand, given a constant thickness of the mold bottom, more remachining is possible without an overly deep profiling preventing the remachining. 
     The profiling is advantageously designed to provide a largest possible surface area. Therefore, the profiling may not only extend in the area of the inner side of the casting wheel, but also at the outer sides of the lateral faces between which the casting channel is located. This altogether increases the size of the profiled surface. The radial end faces of the mold bottom may also be provided with such a profiling. 
     Another approach provides that the profiling be formed from a plurality of grooves. Since easy machining is possible, these grooves should extend peripherally in the circumferential direction of the casting wheel. The production may be accomplished by recessing the grooves. 
     The profiling itself should be maximized with regard to the surface area thereof. With regard to the profiling, a serrated or undulated profile is preferably used. If the profiling is too delicate, the individual grooves may become obstructed, decreasing the size of the surface area that comes in contact with the cooling fluid. For that reason, the grooves should preferably have an opening angle of 15° through 90°. In particular, the opening angle is 45° to 60°. On the one hand, such grooves should be more readily produced than grooves having mutually parallel extending side walls. On the other hand, in the case of the mentioned opening angles, capillary forces hardly occur, so that the cooling fluid is not drawn into the grooves to remain therein, rather is constantly exchanged. The heat is dissipated more effectively. 
     To avoid adhesion, the mold bottom regions and/or the lateral faces of the casting wheel acted upon by cooling fluid may be provided with a coating that protects the casting wheel from cooling fluid deposition. 
     The coating may be an antiadhesive coating. In particular, the coating contains silicon compounds, aluminum compounds or titanium compounds. These are preferably what are generally referred to as nano coatings, respectively lotus-effect coatings having layer thicknesses of between 4 μm and 10 μm. Nano coatings are understood to be structures whose molecules are within the scale of less than 100 nanometers. 
     This requires a small layer thickness on the order of 4 μm to 10 μm to ensure an efficient heat transfer in the application case of the present invention. 
     A nano coating is preferably applied by spraying or by lacquering/coating. A dipping process may also be used for the lacquering. Following application of the nano coating to the appropriate surfaces of the casting wheel, the liquid nano coating is converted to a solid nano coating in a curing process. The cured nano coating has a smooth and closed surface. 
     To a certain degree, the requirement for a smooth surface is also that the roughness of the surface of the casting wheel in the areas in question be reduced. A roughness of between 2 μm and 5 μm is adjusted. Following irradiation or polishing of the surface, the surface is degreased. The liquid nano coating is subsequently applied. Any cavities in the surface are sealed, preventing any more deposits from settling. 
     The nano coating is then able to substantially improve the surface properties of the casting wheel, the thermal conductivity being negligibly influenced. The fundamental advantage of the coating is that contamination or calcification contained in the cooling fluid does not settle on the coated surfaces, rather is rinsed away from the surface by the flow of cooling fluid. A self-cleaning effect of the surface is utilized. 
     In an exemplary embodiment,  FIG. 1  schematically shows a cross section through a casting wheel  1  of which only one casting channel is shown due to the axially symmetric configuration. Therefore, the illustrated cut-away portion of casting wheel  1  shows a casting channel  2  that is used for receiving liquid metals or metal alloys. Casting channel  2  is covered by a band  11  over a partial peripheral area of casting wheel  1 , until the molten metal received therein is at least externally solidified and, therefore, emerges as a solid strand from the casting wheel. The area underneath casting channel  2  is referred to as mold bottom  3 . Mold bottom  3  has two radially outwardly extending lateral faces  4 ,  5  between which casting channel  2  is located that, in cross section, essentially has a trapezoidal configuration. The contouring of casting channel  2  is purely exemplary. 
     Of importance in the case of the casting wheel according to the present invention is a profiling  6  at inner side  7  of mold bottom  3  facing away from the casting channel. Profiling  6  is shown in an enlarged view in the lower portion of the illustration. Profiling  6  has a profile height within a range of from 0.5 mm to 6 mm, preferably within a range of from 0.5 mm to 3 mm. In this exemplary embodiment, the profile height is 1 mm. Profile width B is 2 mm. Profiling  6  is configured as a serrated profile because a plurality of identically configured grooves are disposed side-by-side. Grooves  8  each have an opening angle W of 90°. Angle W is preferably within a range of from 15° to 90°, in particular within a range of from 45° to 60°. 
     Inner side  7  of mold bottom  3  is acted upon by a cooling fluid in a manner not shown in greater detail. The cooling fluid is sprayed onto inner side  7 . As the result of profiling  6 , the surface area in the region of inner side  7  is enlarged, so that heat flow Q from the casting strand into the cooling fluid is influenced by the proportionality to surface A of profiling  6 . 
     Further profilings  6   a,    6   b  are configured at outer sides  9 ,  10  of lateral faces  4 ,  5 . Profilings  6   a,    6   b  are configured there exactly as at inner side  7  of mold bottom  3 . In this area as well, a significantly greater heat flow may be realized, which is attributable to the enlargement of the particular surface areas. The inventive configuration of the surface areas of casting wheel  1  has the decisive advantage of allowing the casting wheel to be remachined under conditions of increasing wear, without profiling  6 ,  6   a,    6   b  disrupting this process. Relative to the dimensions of casting wheel  1 , profiling  6 ,  6   a,    6   b  is so small, but nevertheless so effective that it exclusively improves the method of functioning of the casting wheel, without standing in the way of any potential remachining. 
     In a manner not shown in greater detail, casting wheel  1  is provided in the area of profilings  6 ,  6   a,    6   b  with a coating that prevents cooling fluid deposits from settling. It is a question, in particular, of an antiadhesive coating. In particular, the coating may be what is generally referred to as a nano coating that contains silicon compounds, aluminum compounds or titanium compounds. 
     LIST OF REFERENCE NUMERALS 
     
         
           1 —casting wheel 
           2 —casting channel 
           3 —mold bottom 
           4 —lateral face 
           5 —lateral face 
           6 —profiling 
           6   a— profiling 
           6   b— profiling 
           7 —inner side 
           8 —groove 
           9 —surface area 
           10 —surface area 
           11 —band 
         H—height 
         B—width 
         W—angle