Title of Invention	A STRIP CASTING DEVICE
Abstract	A strip casting device with a circulating belt. In the cooling area, the belt is sucked against carriers by a negative pressure in the cooler. The carriers are arranged so that, with given mechanical properties of the circulating belt, a deflection that compensates for the thermal elongation takes place between the supporting surfaces of the carriers.

Full Text

STRIP-CASTING INSTALLATION The invention relates to a strip-casting installation. The term 'strip-casting installation' is herein used to describe a plant in which the liquid steel is transported via a feed system to a revolving belt which is cooled from below by means of water. The lower side of the applied steel layer solidifies in contact with the belt, and the upper side, as a free surface, under an inert gas or, to obtain a higher-quality surface finish, in contact with a top roller. Once thoroughly solidified, the resultant continuous casting (the strip) leaves the revolving conveyor belt and is transported onward by a driver unit. Depending on the thickness required in the hot strip on completion of rolling (1 to 3 mm) and depending on the necessary hot deformation to achieve satisfactory material properties, it is possible for the casting thickness of the strip (about 10 mm) to be selected so as to be substantially optimal. The optimal casting thickness in this regard is that thickness at which the required degree of hot deformation is achieved with the minimum of deformation work. The revolving conveyor belt permits a cooling and a substantially frictiori-free support of the continuous casting over an extended sector. The results hereof are a high casting rate, such as is a pre-requisite for a direct coupling of the casting plant and the rolling step, and a high rate of productivity as a fundamental requirement for the casting of tonnage steel. The revolving belt, which is accessible from above and from the front, simplifies the feeding of the steel. It is not necessary for the steel, as in other processes, to be introduced into a narrow gap between two belts or rollers. A cooling means (water cooling with suitable nozzles) is arranged in the region between the transport rollers for the revolving belt in order to cool the belt on that side which faces away from the steel. Despite this cooling operation, an arching of the revolving belt takes place because of the high temperatures resulting from the steel melt which is applied to the upper side of the belt. This arching results in a shaping in the surface of the continuous casting. In order to prevent the arching, a partial vacuum is set in the cooling means. As a result of the difference in pressure, the revolving belt is pressed, for example, on to supporting rollers. Formerly used supporting rollers (Production of steel strip with a single-belt process, K.-H. Spitzer and K. Schwerdtfeger, ISM November 1995, page 51) had a longitudinal section comprising grooves, (Figure 12 of the publication) , the supporting rollers thus had a profiled surface, the profile, in a longitudinal section, having sections with a greater diameter as opposed to the minimum roller diameter. The width of these spacings previously corresponded substantially to the spacing between the sections. In such roller constructions, or in any other supports, in which the spacing between the bearing surfaces of the revolving belt corresponded essentially to their breadth, it was not possible for the stresses in the revolving conveyor belt resulting, in particular, from the thermal load, to be reduced in a controlled manner. As soon as the stability threshold is exceeded by too high stresses, the revolving belt arches, usually in the middle region. Thus, the partial vacuum set in the previously used roller construction does not produce the desired results, since the arching of the revolving belt continues to influence the shape of the continuous casting in an undesirable manner. Accordingly, it was the object of the invention to provide a strip-casting installation in which the maximum deflection of the conveyor belt from the surface defined by the supports is reduced to a minimum. It is thus intended to reduce the arching. According to the invention, in a strip-casting plant or installation comprising a melt feeding means and a revolving conveyor belt which is pressed against supports by a partial vacuum, the supports are arranged at spacings such that, depending on the prevailing mechanical properties of the revolving belt and depending on the known mechanical and thermal stresses, a bending (arching) takes place between a plurality of bearing surfaces to accommodate the thermal elongation. More particularly according to one aspect of the invention there is provided a strip-casting installation comprising melt-feeding means and a revolving belt for cooling the cast melt and comprising supports for supporting the revolving belt, a partial vacuum being applied on the side of the belt which faces the supports, the bearing surfaces of the supports being spaced apart such that, with the prevailing mechanical properties of the revolving belt, a curving takes place between the bearing surfaces for accommodating the thermal elongation. In this regard, the arching is divided into a plurality of smaller archings. The supports preferably comprise non-continuous bearing surfaces, and the spacing between the supports, and of the bearing surfaces with respect to one another, is, in particular, greater than the length of the bearing surface, measured in the direction of measuring the spacing. It is possible for the optimal spacing between the bearing surfaces to be determined in conjunction with the partial vacuum and the known mechanical and thermal stress, and in conjunction with the prevailing peripheral parameters and the known mechanical properties of the revolving strip. The spacing between the bearing surfaces of adjacent supports is preferably at least twice the length of a bearing surface, measured in the direction of the spacing. Any means may be used as the supports. A preferred form of the supports comprises supporting rollers which are provided with a profiled surface. In a longitudinal section, this surface has sections which, relative to the minimum roller diameter, have a greater diameter, while, in the longitudinal direction of the roller, the breadth of the sections is smaller than the spacing between the sections. In other words, this means that, between the sections having a greater diameter is disposed a spacing which is a multiple of the breadth, as measured in the longitudinal direction of the supporting rollers, of the sections which support the revolving belt. As a result hereof, it is ensured that the revolving belt no longer arches, but is drawn by the difference in pressure into the regions between the sections having a greater diameter. The arching of the belt is thus reduced or, instead of a major arching, a plurality of smaller archings take place along the breadth and length of the revolving belt. According to another aspect of the invention there is provided a supporting roller for a strip-casting installation the roller having a profiled surface, the profile of which, in the longitudinal section, comprises sections having a larger diameter relative to the minimum roller diameter, and, in the longitudinal direction of the roller, the breadth of the sections is smaller than the spacing between the sections-. According to a preferred embodiment, the spacing between the sections having a greater diameter is at least twice the breadth of the sections, measured in the longitudinal direction of the rollers. As a result hereof, it is ensured that a sufficiently large surface area is provided between the bearing points of the sections having the greater diameters and the revolving belt, such that a controlled reduction of the stresses in the longitudinal direction of the roller is possible. According to a further preferred embodiment, the sections having a greater roller diameter have, in a longitudinal section of the roller, an essentially rectangular shape. The sections are then to be regarded essentially as discs, the thickness of which corresponds to the breadth of the sections, measured in the longitudinal direction of the rollers. This shape contributes to providing a greater support for the belt and provides an increased bearing surface in comparison to tapering shapes. According to a further preferred embodiment, the essentially rectangular shape of the sections is designed to be trapezoidal, the sections having a greater diameter, previously described as discs, thus having edges which are bevelled or rounded-off in the region of the corners. As a result hereof, it is possible for the revolving belt to follow the pressure directed toward the axis of the roller even more intensely, without the above-described advantage of the increased bearing surface and greater supporting effect. According to a further preferred embodiment, the sections having a greater diameter form an angle with the axis of the roller of less than 90°. In this embodiment, the sections, previously described as discs, are thus not disposed perpendicularly relative to the axis of the supporting rollers, but are arranged at an angle thereto. As a result hereof, the bearing surface is increased still further. It is, in particular, also possible for the sections having a greater diameter to extend helically about the axis of the supporting roller, it thus being possible for transverse forces to be carried off more effectively. The arrangement, according to the invention, in respect of one of the above-described . supports, or supporting rollers, provides that the bearing surfaces of a roller, or of a series of supports, is arranged so as to be staggered relative to the bearing surfaces of the adjacent roller or series of supports. As a result hereof, it is possible to prevent the formation of groove-like recesses in the revolving belt, which would otherwise possibly produce impressions in the surface of the steel strip. * According to still another aspect of the invention there is provided a supporting roller arrangement for supporting rollers of the type described above in which sections of a roller, in the longitudinal direction of the roller, are arranged to be offset relative to the sections of an adjacent roller. According to a further preferred embodiment, the bearing surfaces are offset relative to each other such that the bearing surfaces of one roller, or of a series of supports, are arranged substantially in the centre between the bearing surfaces of the adjacent roller, or series of supports. In a further preferred arrangement, in supporting rollers, the sections having a greater diameter in adjacent supporting rollers are arranged at an angle relative to each other. In this embodiment, the "discs" of adjacent supporting rollers are not only disposed at an inclination relative to the respective roller axis, but are also disposed at an inclination relative to each other, in a herringbone pattern. It is also possible for the supports to be designed and arranged correspondingly. While the sections having a greater diameter have been described as discs, this should not be regarded as a limitation, but merely as an illustration. It is possible for the sections having a greater diameter to be designed such that their breadth is greater than their diameter. In that instance, the sections having a greater diameter then rather assume the shape of a short tubular piece. It is, in particular, also possible for the supports to be in the form of individual rollers or runners. An exemplified embodiment is diagrammatically illustrated in the drawings, in which: Figure 1 is a longitudinal section of a supporting roller; and Figure 2 is a longitudinal section of a supporting roller which is adjacent to the supporting roller illustrated in Figure 1 Figure 1 shows a supporting roller 1 in a longitudinal section. The supporting roller extends transversely across the breadth of the revolving belt 2, i.e. also transversely relative to the direction of transportation of the thin strip 3 cast. The supporting roller 1 comprises sections 4, the diameter of which is greater relative to the minimum roller diameter 5. The breadth a of the sections 4 is smaller than the spacing b between the sections 4. Figure 2 shows the roller l' which is adjacent to the roller 1 of Figure 1. The track of the sections 4 shown in Figure 1 is illustrated as a broken line (in Figure 1) and is transferred as a broken line to Figure 2. The track of the sections 4 of the roller 1 is thus disposed in the centre between the sections 4' of the roller 1' . In the longitudinal section illustrated, the sections 4, and 4' respectively, have an essentially rectangular shape. At their narrow sides, they are preferably provided with bevelling or rounded-off regions 6, providing an essentially trapezoidal cross-section. The revolving belt 2 is arched in the direction of the roller axis between the sections 4 (4') of the respective rollers. At a first approach, this relatively small arching does not produce an impression on the thin strip 3 cast, or it is virtually-negligible in comparison to the arching which otherwise extends along practically the entire length of the rollers. WE CLAIM! 1. Strip-casting installation comprising melt-feeding means and a revolving belt for cooling the cast melt and ; comprising supports for supporting the revolving belt, a partial vacuum being applied on the side of the belt which faces the supports, the bearing surfaces of the supports being spaced apart such that, with the prevailing mechanical properties of the revolving belt, a curving takes place between the bearing surfaces for accommodating the thermal elongation. 2. Strip-casting installation according to claim l, in which the spacings between the bearing surfaces are at least twice the lengths of the bearing surfaces, measured in the direction of the spacings. 3. Supporting roller for strip-casting installation the roller having a profiled surface, the profile of which, in the longitudinal section, comprises sections having a larger diameter relative to the minimum roller diameter, and, in the longitudinal direction of the roller, the breadth of the sections is smaller than the spacing between the sections. 4. Supporting roller according to claim 3, in which the spacing between the sections is at least twice the breadth of the sections. 5. Supporting roller according to claim 3 or claim 4, in which, in a longitudinal section of the roller, the sections have a substantially rectangular shape. 6. Supporting roller according to claim 5, in which the substantially rectangular shape of the sections is designed to be trapezoidal on the narrow sides. 7. Supporting roller according to any one of claims 3 to 6, in which the sections form an angle with the roller axis. 8. Supporting roller arrangement for supporting rollers according to any one of claims 3 to 7, in which the sections of a roller, in the longitudinal direction of the roller, are arranged to be offset relative to the sections of an adjacent roller. 9. Supporting roller arrangement according to claim 8, in which the sections of a roller are arranged centrally relative to the sections of an adjacent roller. 10. Supporting roller arrangement according to claim 8 or claim 9, in which the sections of adjacent supporting rollers are disposed at an angle relative to each other. 11 - Strip casting instal1ation, substantially as hereinabove described and illustrated with reference to the accompanying drawings.

Documents:

1183-mas-1997-abstract.pdf

1183-mas-1997-claims duplicate.pdf

1183-mas-1997-claims original.pdf

1183-mas-1997-correspondence others.pdf

1183-mas-1997-correspondence po.pdf

1183-mas-1997-description complete duplicate.pdf

1183-mas-1997-description complete original.pdf

1183-mas-1997-drawings.pdf

1183-mas-1997-form 1.pdf

1183-mas-1997-form 26.pdf

1183-mas-1997-form 3.pdf

1183-mas-1997-form 4.pdf

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