CHOP GATE AND NOZZLE
A shop gate and a nozzle are suitable for being coupled with the bottom floor of a tundish, said nozzle comprising a hollow tube with an axial bore extending from an inlet opening at a first end of the nozzle to an opposite outlet opening at or adjacent the second, opposite end, and comprising a flange extending substantially normal to the axis of the tube and located between said first and second ends, characterized in that the flange comprises a lower, guiding surface facing towards the second end of the tube, said guiding surface being flat and substantially normal to the tube.
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1. Field of the Invention
The present invention generally relates to metal forming lines such as continuous metal casting lines. In particular, it relates to a pouring nozzle design allowing a safe and reproducible emergency sealing of the through bore thereof in case of problem during the casting operation.
2. Description of the Related Art
In metal forming processes, metal melt is transferred from one metallurgical vessel to another, to a mould or to a tool. For example, as shown in
In case of emergency, it must be possible to seal the through bore of the nozzle system (1) to interrupt the casting of metal melt. Some tundishes are equipped with a nozzle exchange device. In such devices, the inner nozzle and the outer pouring nozzles are two separate parts, which are mounted on either side of the frame of the nozzle exchange device in tight contact with one another, In case of emergency, the outer nozzle can be replaced by a new one or by a blank plate sealing the through bore of the inner nozzle.
An alternative solution to nozzle exchange devices is to chop off the outer nozzle portion (4b) of an integral nozzle system (i.e., comprising both inner and outer nozzle portions in one piece) with a chopper or chopping means. The integral nozzle is fixed to the tundish floor by embedding the inner nozzle portion thereof in the refractory lining of the tundish. The outer nozzle portion of the integral nozzle, protruding out of the tundish is engaged in a chopping device (100) comprising a sliding knife having a sharp leading edge resting on a wall of the tubular portion of the outer section of the nozzle and able to slide across the nozzle tubular portion chopping it off by actuation of a pneumatic, hydraulic, or mechanical arm. A blank plate follows the leading edge to theoretically seal the gaping through bore of the upstream section of the nozzle left intact. The problem with such chopping devices is that in order to have a tight contact between the blank plate and the cut off section of the nozzle tubular portion, the edges of the cut need be smooth and straight. This is seldom the case with state of the art chopping devices (100), which generally produce jagged cut sections. Such devices are therefore able to stop the flow of metal melt but rarely to stop it properly allowing metal infiltration and fins around the sealing area and the mechanism.
The present invention proposes a solution for the formation of a tight contact between the edges of the chopped off tubular portion of a nozzle and the plate of the chopper or chopping means of a chopping device. These and other aspects of the present invention are discussed in continuation.
BRIEF SUMMARY OF THE INVENTIONThe present invention is defined by the attached independent claims. The dependent claims define advantageous embodiments. In particular, the present invention concerns a chop gate device comprising a frame defining an upper portion, a mid portion, and a lower portion, and further comprising
- (a) A nozzle comprising a hollow tube with an axial bore extending from an inlet opening at a first end of the nozzle to an opposite outlet opening at or adjacent the second, opposite end, and comprising a flange extending substantially normal to the axis of the tube and located between said first and second ends, thus defining a first, inner nozzle portion extending from the flange and the inlet and a second, outer nozzle portion extending from the flange to the outlet, wherein the flange comprises a top, clamping surface facing towards the first, inner nozzle portion, and a lower, guiding surface facing towards the second, outer nozzle portion, said guiding surface being flat and substantially normal to the tube, said nozzle being coupled to the frame such that the first inner portion extends above the frame upper portion, the flange is clamped to the frame mid portion by clamping means, and the second, outer portion extends below the frame lower portion,
- (b) A chopper or chopping means comprising a plate defining a first and second opposite major surfaces separated by the thickness of the plate, and a sharp chopping leading edge, said plate being slidingly mounted in the frame mid portion, such that the first main, sealing surface thereof is parallel to and contacts the flange guiding surface of the nozzle, and such that the chopping leading edge can contact one side of the second outer portion and can be driven parallel to the flange guiding surface across to the other side of the second outer portion; and
- (c) A pusher or pushing means capable of forcing the chopping leading edge through the second outer portion of the nozzle and thus sever it off from the nozzle flange and first inner portion, such that the first main surface of the chopping plate seals the bore at the level of the flange guiding surface.
In order to ensure an excellent, tight and sealed contact between the sealing surface of the chopper or chopping means and the guiding surface of the nozzle flange, the device frame comprises a presser or pressing means resiliently pressing on the chopper or chopping means to press the chopper or chopping means sealing surface against the flange guiding surface or flange guiding means.
The frame of the chop gate device is provided with a clamp or clamping means for fixing the nozzle to the frame. In an advantageous embodiment, said clamp or clamping means are designed to apply a clamping force onto the flange clamping surface and thus fix in place the nozzle to a receiving surface of the frame. The clamping force may be substantially normal to the clamping surface of the flange. In an advantageous embodiment, the clamping surface of the flange is slanted with respect to horizontal, and the clamp or clamping means apply a clamping force substantially normal to said slanting clamping surface. This geometry allows the nozzle to be centered within the frame of the chop gate device by the clamping forces applied on various sides of the nozzle to said slanting clamping surface.
Unlike the state of the art integral nozzles, the present nozzle is coupled to the frame of the chop gate device by clamping thereto the flange of the nozzle. This ensures a perfect alignment of the nozzle with the frame and chopper or chopping means mounted on the same frame. It is only after clamping the nozzle to the frame that the inner nozzle portion of the integral nozzle is embedded in the lining of the tundish.
In an advantageous embodiment, the clamp or clamping means comprise three clamping elements, the centroids of said three clamping elements forming the summits of a triangle having two summits on either side of the diameter of the cross section of the axial bore passing by the third summit. Such clamping elements are to be used with a nozzle which clamping surface comprises three separate support rims jutting out and distributed around the perimeter of the tube, which centroid form a triangle which summits match the summits of the triangle formed by the clamping elements.
In order to achieve as clean a cutting surface as possible when chopping the tube off, it is advantageous if the outer nozzle portion comprises a weakening notch at the interface between the flange guiding surface and the second outer portion, leveled with the leading edge of the chopper or chopping means.
The present invention also concerns a tundish comprising a chop gate device as discussed supra fixed to the outside of the bottom floor thereof, such that the first inner portion of the nozzle protrudes through an opening in the floor of the tundish and is embedded within the refractory layer lining the inner walls of the tundish.
Finally, the present invention also concerns a nozzle suitable for being coupled with the bottom floor of a tundish, said nozzle comprising a hollow tube with an axial bore extending from an inlet opening at a first end of the nozzle to an opposite outlet opening at or adjacent the second, opposite end, and comprising a flange extending substantially normal to the axis of the tube and located between said first and second ends, thus defining a first, inner nozzle portion extending from the flange and the inlet and a second, outer nozzle portion extending from the flange to the outlet, wherein the flange comprises a top, clamping surface facing towards the first, inner nozzle portion, and a lower, guiding surface facing towards the second, outer nozzle portion, said guiding surface being flat and substantially normal to the tube, characterized in that, the outer nozzle portion comprises a weakening notch at the interface between the flange guiding surface and the second outer portion. In one embodiment, the weakening notch may extend around a portion only of the perimeter of the outer nozzle portion. In order to obtain an even cleaner cut, however, the weakening notch may extend around substantially the whole perimeter of the outer nozzle portion.
In one embodiment the flange clamping surface (5a) is slanted, reducing the thickness of the flange (5) away from the tube. The slanting angle may be comprised between 30 and 60° with respect to horizontal, and may be 45°. In an advantageous embodiment the second, outer portion forms a shroud nozzle and the outlet is formed by at least one window, and may be formed by two or four windows opposed two by two and opening to ambient and being distributed around the peripheral wall of the second outer portion adjacent the second end thereof. In an alternative embodiment, the second outer portion forms a pouring nozzle and the outlet opens axially at the second end of said second outer portion.
In a particular embodiment, the nozzle clamping surface comprises three separate support rims jutting out and distributed around the perimeter of the tube, the centroids of said three support rims forming the summits of a triangle having two summits on either side of the diameter of the cross section of the axial bore passing by the third summit.
In order to mechanically strengthen the flange of the nozzle some or all the flanges surfaces, bar the guiding surface, are at least partly clad with a metal casing. For a nozzle comprising three rims as discussed supra, it is advantageous that the three separate support rims be part of the metal casing.
Various embodiments of the present invention are illustrated in the attached Figures:
As can be seen in
The flange (5) of a nozzle according to the present invention has several functions. First, the flange is used to clamp the nozzle to a matching receiving surface of the frame of the chop gate device (100) by applying a clamping force by a clamp or clamping means (104) to the second, clamping surface (5a) of the flange. This ensures that the nozzle be perfectly aligned with the frame and sliding chopper or chopping means (101). The clamping forces may be applied substantially normal to the clamping surface (5a) of the flange. As illustrated in
Second, the flange first guiding surface (5b) has the function of guiding the chopper or chopping means as it runs across the tube. This is achieved by the first surface (5b) facing towards the outlet (2b) which acts as a guiding surface, and as such is flat and substantially normal to the tube.
Third, the guiding surface (5b) ensures a tight contact between the remaining portion of the nozzle and the chopper or chopping means, thus sealing the through bore of the inner nozzle portion (4a) and stopping the flow of metal melt altogether. Indeed, the chopper or chopping means (101) comprise a plate suitable for sliding along a plane substantially normal to the axis of the nozzle. Said plate comprises a leading edge (101c) which is sharp and hard enough to cut the way of the plate through the tube bringing a main, sealing surface (101b) of the plate vis-à-vis the through bore of the upstream portion of the nozzle still in place. The combination of a straight course of the chopper or chopping means during the chopping operation, and the tight contact between the chopping plate (101) and the guiding surface (5b) of the flange (5) ensure that in case of emergency, the flow of metal melt can reliably be interrupted altogether at any time by actuation of the chopper or chopping means (101). In order to ensure a tight contact between the sealing surface (101b) of the chopper or chopping means (101) and the guiding surface (5b) of the nozzle flange (5), the frame of the chop gate device is provided with a presser or pressing means (105) resiliently pressing on the chopper or chopping means (101) to form a tight and sealing contact between the chopper or chopping means sealing surface (101b) and the flange guiding surface or flange guiding means (5b). As illustrated in
Fourth, the geometry of the flange perimeter may help to control the angular orientation of the nozzle with respect to its central axis. This is particularly important for nozzles having outlets opening laterally on the wall of the tubular portion of the nozzle, as illustrated in
- a) the guiding surface (5b) is flat and substantially normal to the axis of the nozzle tube, in accordance with the present invention, and
- b) the tundish nozzle is aligned with respect to the frame of the chop gate device trough the clamping means and not, as in traditional designs, aligned with respect to the floor of the tundish. This innovative concept allows the nozzle and chopper or chopping means to be systematically in perfect alignment.
The flange, like the rest of the nozzle is made of a refractory material to resist the high temperatures of a metal melt. The flange (5) is at least partly clad with a metal casing for reinforcing it as it is submitted to clamping stresses applied by the clamp or clamping means (104) of the chop gate device. The guiding surface (5b), however, shall not be clad with a metal casing (22) because in case of actuation of the chopper or chopping means, said surface must form a tight, heat resistant contact with the chopping plate (101). If the guiding surface (5b) were clad with a metal casing (22) it may contact metal melt and melt itself thus provoking leaks.
In order to promote the formation of a “clean” chopped off surface, the tubular portion of a nozzle according to the present invention must comprise a weakening notch (6) at the interface between the flange guiding surface (5b) and the second outer portion (4b). The notch may run around the whole circumference of the tube as illustrated in
As illustrated in
The plate is usually made of casting steel but it may also be made of a refractory material as, in case of use, the main top, sealing surface (101b) thereof will seal the through bore of the nozzle extending upstream from the flange (5) and thus be in contact with metal melt. The leading edge, on the other hand, may be reinforced with a hardened material, such as carbides and the like. The guiding surface (5b) of the flange of the nozzle serve both as guiding surface to ensure that the leading edge (101c) follows the desired course, but also as sealing surface in matching collaboration with the sealing surface (101b) following gapless downstream of the leading edge (101c). Both flange guiding surface (5b) and sealing surface (101b) should be made of bare refractory material (i.e., not clad with a metal casing), lest a metal leak would melt a portion of casing cladding such surfaces.
Actuation of the chopping plate is driven by a mechanical, pneumatic, or hydraulic arm (102), able to push the chopper or chopping means (101) from a casting position, allowing the metal melt to flow undisturbed (cf.
A chop gate device (100) as defined supra is fixed to the outside of the bottom floor (10a) of a tundish (10). A nozzle as defined supra can then be clamped into position onto the frame of the device (100) by the action of a clamp or clamping means on the flange clamping surface (5a). The first inner portion (4a) of the nozzle (1) protrudes through an opening in the floor (10a) of the tundish thus forming an inner nozzle, which can then be embedded within the refractory layer (10b) lining the inner walls of the tundish. The refractory layer may comprise a well block for housing the inner portion (4a) of the nozzle. The flange (5) and second outer portion (4b) of the nozzle, on the other hand, stand outside of and below the tundish. A tundish thus equipped is safe to use as the casting operation can easily be interrupted in case of emergency and the flow of metal melt stopped almost instantly. This is rendered possible by the use of a nozzle according to the present invention that comprises a specific flange guiding surface (5b) capable of guiding a chopper or chopping means linearly along a well defined trajectory to chop a portion of the nozzle along a straight plane. On the other hand, the sealing surface (101b) of the plate of the chopper or chopping means (101) also acts as blank plate, sealing the bore (2) of the nozzle portion still in place, i.e., standing upstream from the guiding surface (5b), with the advantage that there is no gap between the leading edge (101c) and the sealing surface (101b).
In the embodiment illustrated in
The centroids of the three support rims form the summits of a triangle having two summits on either side of the diameter of the cross section of the axial bore (2) passing by the third summit. In other words, the inner nozzle comprises a vertical central longitudinal plane, wherein the three wedging rims are arranged in a Y shape on the periphery of the nozzle, the base of the Y being arranged in the central longitudinal plane and the two arms of the Y being arranged on either side of said plane. The second and third wedging rims have second and third clamping surfaces (5a), each of said second and third surfaces being arranged on either side of the longitudinal plane and having a centre positioned at an angle between 30 and 45° in relation to the longitudinal plane, with reference to the centre of the inner nozzle. Although not essential, it is advantageous that said second and third clamping surfaces of the nozzle be arranged symmetrically in relation to the longitudinal plane. The first clamping rim comprises a first clamping surface, said surface passing through the longitudinal plane and extending substantially symmetrically in relation to said plane, in a surface included in an angular sector between 14 and 52° with reference to the centre of the inner nozzle.
As illustrated in
Numerous modifications and variations of the present invention are possible. It is, therefore, to be understood that within the scope of the following claims, the invention may be practiced otherwise than as specifically described.
Claims
1-15. (canceled)
16. Chop gate device comprising a frame defining an upper portion, a mid portion, and a lower portion, and further comprising
- (a) a nozzle comprising a hollow tube with an axial bore extending from an inlet opening at a first end of the nozzle to an opposite outlet opening at or adjacent the second, opposite end, and comprising a flange extending substantially normal to the axis of the tube and located between said first and second ends, thus defining a first, inner nozzle portion extending from the flange and the inlet and a second, outer nozzle portion extending from the flange to the outlet, wherein the flange comprises a top, clamping surface facing towards the first, inner nozzle portion, and a lower, guiding surface facing towards the second, outer nozzle portion, said guiding surface being flat and substantially normal to the tube, said nozzle being coupled to the frame such that the first inner portion extends above the frame upper portion, the flange is clamped to the frame mid portion by a clamp, and the second, outer portion extends below the frame lower portion,
- (b) a chopper comprising a plate defining a first and second opposite major surfaces separated by the thickness of the plate, and a sharp chopping leading edge, said plate being slidingly mounted in the frame lower portion, such that the first main, sealing surface thereof is parallel to and contacts the flange guiding surface of the nozzle, and such that the chopping leading edge is configured to contact one side of the second, outer portion of the nozzle and is configured to be driven parallel to the flange guiding surface across to the other side of the second outer portion; and
- (c) a pusher configured to force the chopping leading edge through the second outer portion of the nozzle and thus sever it off from the nozzle flange and first inner portion, such that the first main surface of the chopping plate seals the bore at the level of the flange guiding surface.
17. Chop gate device according to claim 16, comprising a presser resiliently pressing on the chopper to form a tight and sealing contact between the chopper sealing surface and the flange guiding surface.
18. Chop gate device according to claim 16, comprising a clamp configured to applying a clamping force onto the flange clamping surface and configured to fix in place the nozzle to a receiving surface of the frame.
19. Chop gate device according to claim 18, wherein the clamp comprises three clamping elements, the centroids of said three clamping elements forming the summits of a triangle having two summits on either side of the diameter of the cross section of the axial bore passing by the third summit and wherein the nozzle clamping surface comprises three separate support rims jutting out and distributed around the perimeter of the tube, which centroid form a triangle which summits match the summits of the triangle formed by the clamping elements.
20. Chop gate device according to claim 16, wherein the outer nozzle portion comprises a weakening notch at the interface between the flange guiding surface and the second outer portion, leveled with the leading edge of the chopper.
21. Chop gate device according to claim 18, wherein the flange clamping surface of the nozzle is slanted, reducing the thickness of the flange away from the tube.
22. Tundish comprising a chop gate device according to claim 16, wherein the chop gate device is fixed to the outside of the bottom floor of the tundish, such that the first inner portion of the nozzle protrudes through an opening in the floor of the tundish and is embedded within the refractory layer lining the inner walls of the tundish.
23. Nozzle suitable for being used in the chop gate device of claim 16, said nozzle comprising a hollow tube with an axial bore extending from an inlet opening at a first end of the nozzle to an opposite outlet opening at or adjacent the second, opposite end, and comprising a flange extending substantially normal to the axis of the tube and located between said first and second ends, thus defining a first, inner nozzle portion extending from the flange and the inlet and a second, outer nozzle portion extending from the flange to the outlet, wherein the flange comprises a top, clamping surface facing towards the first, inner nozzle portion, and a lower, guiding surface facing towards the second, outer nozzle portion, said guiding surface being flat and substantially normal to the tube, wherein the outer nozzle portion comprises a weakening notch at the interface between the flange guiding surface and the second outer portion.
24. Nozzle according to claim 23, wherein the flange clamping surface is slanted, reducing the thickness of the flange away from the tube.
25. Nozzle according to claim 23, wherein the second, outer portion forms a shroud nozzle and the outlet is formed by at least one window opening to ambient and being distributed around the peripheral wall of the second outer portion adjacent the second end thereof.
26. Nozzle according to claim 23, wherein the second outer portion forms a pouring nozzle and the outlet opens axially at the second end of said second outer portion.
27. Nozzle according to claim 23, wherein the weakening notch extends around substantially the whole perimeter of the outer nozzle portion.
28. Nozzle according to claim 23, wherein the nozzle clamping surface comprises three separate support rims jutting out and distributed around the perimeter of the tube, the centroids of said three support rims forming the summits of a triangle having two summits on either side of the diameter of the cross section of the axial bore passing by the third summit.
29. Nozzle according to claim 23, wherein the flange is partly clad with a metal casing with the exception of the guiding surface.
30. Nozzle according to claim 28, wherein the three separate support rims are part of the metal casing.
31. Chop gate device of claim 21, wherein the slanting angle is comprised between 30 and 60° with respect to horizontal.
32. Chop gate device of claim 21, wherein the clamping means apply a clamping force substantially normal to the slanting clamping surface of the flange.
33. Nozzle according to claim 24, wherein the slanting angle is comprised between 30 and 60° with respect to horizontal.
34. Nozzle according to claim 25, wherein the outlet comprises pairs of opposed windows.
Type: Application
Filed: Jun 27, 2012
Publication Date: Apr 17, 2014
Applicant: VESUVIUS GROUP, S.A. (Ghlin)
Inventor: Jean-luc Renard (Saint-Symphorien)
Application Number: 14/126,553
International Classification: B22D 41/50 (20060101);