1. Field of the Invention
The invention is directed to a device for casting strands of metal, in particular steel, with a material supply vessel, the liquid metal being delivered to the carrying side of a circulating conveyor belt by a pouring nozzle of the material supply vessel, wherein the conveyor belt comprises a thin, heat-resistant belt that circulates between a first deflection roller and a second deflection roller, the conveyor belt is shaped after the first deflection roller in a region of the pouring nozzle to form a trough for receiving the liquid metal and the conveyor belt resumes a flat shape in proximity to the second deflection roller.
2. Prior Art
A device of the type mentioned above is known from Japanese Publication 59147755 A, in which the trough shape of the belt is achieved by vertical and horizontal conveying rollers arranged along the conveying path between the two deflection rollers and act on the belt.
Due to the relatively large differences in temperature along a width of the belt that act on the belt through the liquid metal and because of the deformation of the belt from a flat shape to the trough shape and then back again into the flat belt shape, there are widely varying changes in length along the width of the belt resulting in critical stresses on the belt material, particularly in the edge area.
Although the belt—usually a steel belt for this purpose—has an elasticity corresponding to the belt material that is used, a cost-effective lifetime cannot be achieved as a result of the different stresses on the belt along the width.
Therefore, it is an object of the invention to design the device such that the stresses on the belt are reduced and evened out. Further, new materials are used for the belt material because of the reduced, more uniform stress on the belt. Further, the entry length and exit length are adapted to the geometry of the trough profile for specific adjustment of the degree of camber. This increases the cost effectiveness of the casting process appreciably.
The above-stated object is met according to one embodiment of the invention in that at least one of the deflection rollers is cambered in a convex manner.
Owing to a deliberate cambering of at least one of the deflection rollers, by which the shortening of the belt resulting from the formation of the trough profile is at least partially compensated and because the different temperature distribution along the width of the belt is also taken into consideration in the camber, the stress on the belt is made homogeneous, which has a positive impact on the life of the belt.
It is advantageous when the camber of at least one of the deflection rollers is varied by a pressure medium to compensate for the change in length, e.g., due to modified casting parameters. To this end, a profiled cavity is provided in the roller shell. In this connection, it can also be advantageous when the camber of the first deflection roller, is smaller than that of the second deflection roller.
The camber can be calculated based on the geometry of the trough profile. The average trough profile is used for the calculation when the trough profile varies over the length of the trough to adapt to the shrinkage of the casting profile.
In the drawings:
The camber of the rollers 12, 14 is a function of the respective entry belt length Le and exit belt length La between the deflection roller and the trough profile (
The camber is yielded by: f(Le or La,BB,BT,HT, trough profile).
The calculation of the camber is preferably carried out for every point of the deflection roller between points A and B of the trough profile with coordinates X and Y and length Le (a) for half of the belt width BB between points C and D, shown in
The calculation of the different belt length owing to the varying temperature distribution over the width of the belt is carried out in a simplified manner according to the indicated formula. For an exact calculation, the temperature profile over the width of the belt is calculated corresponding to the casting parameters.
By means of the two formulas, the optimum camber of the deflection rollers for homogenized tensile stress over the width of the belt can be calculated for a given trough profile (casting format) and temperature profile by superposition:
B
B/2=XB+X+XT (1)
ΔLXB=L−LV=√{square root over (L2+X2+Y2)} (2)
ΔlTemp=LTroughα(TM−TR) (3)
where
The camber of the first deflection roller 14 is preferably smaller than that of the second deflection roller 12.
The camber should be changeable, e.g., by a pressure medium, in at least one of the deflection rollers 12, 14. To this end, a profiled cavity can be provided at the roller shell for applying pressure.
The entry length and exit length, respectively, should preferably be greater than 500 MM.
The maximum entry length or exit length is selected in such a way that the camber due to the trough profile is not greater than 2%.
The belt is preferably shaped by the deflection roller continuously over the distance Le or La to form the trough profile or flat belt.
A particularly suitable belt material is a thermal shock-resistant alloy based on CuNi, Fe.
The belt material can be made of a single-phase or multiple-phase Cu alloy or a nickel-based alloy.
The belt 10 preferably has a thickness from about 0.5 mm to about 2.0 mm.
The trough profile should have the shape of an arc and is preferably symmetrical.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
Number | Date | Country | Kind |
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102007010578.0 | Feb 2007 | DE | national |
This is a U.S. national stage of Application No. PCT/DE2008/000031, filed on 8 Jan. 2008, which claims Priority to the German Application No.: 10 2007 010 578.0, filed: 26 Feb. 2007 the contents of both being incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE2008/000031 | 1/8/2008 | WO | 00 | 8/10/2009 |