|Title of Invention||
ARRANGEMENT OF SUPPORTS FOR THIN-STRIP CASTING
|Abstract||The invention relates to an arrangement of supports for the conveyor belt in thin-strip casting plants. The liquid steel is poured on to the revolving conveyor belt. On its lower side, the conveyor belt is provided with means for producing a partial vacuum and for supporting the belt, as well as for cooling. Rollers were previously used as support means. It is possible for the belt to arch between the contact points of the belt on the rollers. This is prevented when using supports, the spacings between which are greater, measured in -the direction of transportation, than the length of the supports in this direction.|
ARRANGEMENT OF SUPPORTS FOR THIN-STRIP CASTING
The invention relates to a specific arrangement of the supports in thin-strip casting.
The term 'thin-strip casting' is used here to describe a plant in which the liquid steel is transported via a feed system to ra 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 thin 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 mfh) 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 friction-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 of the continuous casting in its surface. 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 on to supports.
The supporting rollers previously used (Production of steel strip with a single-belt process, K.-H. Spitzer and K. Schwerdtfeger, ISM November 1995, page 51) previously 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, 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,
preferably 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 is an object of the invention to provide a construction of supports and an arrangement of supports in which the arching of the revolving belt is prevented, in particular in the feed region of the liquid steel.
According to the invention there is provided an arrangement of supports for the conveyor belt in thin-strip casting plants, in which the supports are designed to be, in particular, runner-like in the region of the partial-vacuum side of the conveyor belt, the spacing between the supports, when measured transversely to the direction of transportation, being greater than the length of the supports in this direction.
According to the invention, the supports are designed to be, in particular, runner-like in the region of the surface of the conveyor belt, the spacings between the supports, when measured transversely to the direction of transportation, being greater than the length of the supports in this direction. In this regard, the spacings are optimally designed such that, on the one hand, it is possible for the stresses in the belt to be reduced sufficiently, and that, on the other hand, it is not possible for an arching of the belt across a plurality of supports to take place. In the clearance between the supports, the rigidity of the belt is, however, sufficiently high, such that essentially no arching of the belt takes place. In particular, any possible arching is prevented in that, between the supports, the belt is maintained substantially in a plane as a result of the partial vacuum applied to the lower side of the belt.
The length of the supports is preferably greater in the direction of revolving of the conveyor belt than in the transverse direction. The supports, in conjunction with the partial vacuum acting on the lower side of the conveyor belt, bring about a greater restraining of the belt, thereby ensuring still further that an arching of the belt will not take place.
The supports are, in particular, arranged essentially in the plane of the lower side of the conveyor belt in a grid-like manner, the axes of the grid preferably being disposed at an inclination relative to the direction of transportation and,
in particular, at an angle of 45° relative thereto. This results in a more favourable planar distribution of the stresses within the conveyor belt. Since the highest stress components no longer manifest in the transverse direction of the belt, it is no longer possible for an arching to take place in this direction.
The nozzles for the coolant for cooling the conveyor belt are preferably arranged in the spaces of the grid, i.e. between the supports. As a result hereof, it is, in particular, possible for the critical region of the surface of the belt between the supports to be cooled more effectively. In contrast to the use of supporting rollers, the space between the supports is more readily accessible for arranging nozzles for coolant, since it is possible for the supports to be extended downward such that adequate space is provided for the required coolants. It is possible for the supports to be flat on their surface facing the conveyor belt. In particular, it is also possible for this surface to be provided with a coating which reduces friction to a minimum in the tribological system comprising conveyor belt surface, surface of the supports and coolant. It is, in particular, possible for the surface of the supports to be formed by a roller or a plurality of rollers supported on the support.
Nozzles for cooling the conveyor belt are preferably incorporated in the supports according to the invention. On the one hand, these nozzles may be the nozzles which ensure
cooling of the clearances between the supports. Independently thereof, on the other hand, it is possible for the coolant to be guided within the support itself to the surface of the support in the region of the lower side of the conveyor belt. This results in a structurally simple means for cooling the belt even directly on the bearing surface of the supports and for providing a lubricating film between the support and the belt. This bearing surface is, in particular, essentially flat, which is also intended to include the peripheral surface of a cylinder, and ducts for the supply of coolant are arranged in this surface of the supports.
In a further preferred embodiment, it is possible for a plurality of nozzles to be arranged on the single support, said nozzles being directed up to the surface of the support on the lower side of the conveyor belt.
The invention will be described in more detail with reference to an exemplified embodiment which is diagrammatically illustrated in Figures 1 and 2, in which:
is a plan view of the arrangement of supports below the conveyor belt;
shows a section transversely to the direction of transportation.
According to Figure 1, the supports 3, 3' form a grid which has grid axes 2, 2', the grid axes 2, 2' being disposed at an
inclination relative to the direction of transportation 1 of the revolving conveyor belt. The supports 3, 3' are arranged at the intersections of the grid axes 2, 2' . The nozzles 4 for the supply of coolant are arranged in the clearances between the supports 3,3'.
Figure 2 shows the supports 3, 3' which extend up to the lower side 6 of the conveyor belt 5, the nozzle 4 not.being shown for reasons of greater clarity. The supports 3, 3' comprise supply 'ducts 7 for the supply of coolant into the region of the lower side 6 of the conveyor. As a result, it is possible for a coolant film to form between the surface 8 of the support and the lower side 6 of the conveyor belt, thereby preventing friction between these surfaces.
Water is generally used as the coolant. In order to improve the elimination of heat, it is, however, also possible to provide two-phase cooling means for the supports and nozzles. In this regard, it is possible for the support to be cooled by air or by inert gas-
1. Arrangement of supports for the conveyor belt in
thin-strip casting plants, in which the supports are designed
to be, in particular, runner-like in the region of the partial-
vacuum side of the conveyor belt, the spacings between the
supports, when measured transversely to the direction of
transportation, being greater than the length of the supports
in this direction.
2. Arrangement of supports according to claim 1, in
which the length of the supports is greater in the revolving
direction of the conveyor belt than in the transverse
3 . Arrangement of supports according to claim 1 or claim 2, in which, essentially in the plane of the surface of the conveyor belt, the supports are arranged in a grid-like manner, in particular having grid axes which are disposed at an inclination, preferably of less than 45°, relative to the direction of transportation.
4. Arrangement of supports according to claim 3, in which nozzles for cooling the conveyor belt are arranged in the spaces of the grid.
5. Arrangement of supports, in particular according to any one of claims 1 to 4, in which at least one nozzle for
cooling the conveyor belt is arranged in at least one support.
6. Arrangement of supports according to claim 5» in
which,, in the region of that surface of the conveyor belt which
is exposed to a partial vacuum, the surface of the supports is
designed substantially as a plane in which are arranged coolant
7. Arrangement of supports according to claim 5 or claim
6, in which a plurality of nozzles are arranged in at least one
8. Arrangement of supports for the conveyor belt in thin-strip casting plants, substantially as hereinabove described and illustrated with reference to the accompanying drawings.
|Indian Patent Application Number||1187/MAS/1997|
|PG Journal Number||27/2007|
|Date of Filing||03-Jun-1997|
|Name of Patentee||MANNESMANN AKTIENGESELLSCHAFT|
|Applicant Address||MANNESMANNUFER 2, D-40213 DUSSELDROE.|
|PCT International Classification Number||B22D11/06|
|PCT International Application Number||N/A|
|PCT International Filing date|