MXPA97003352A - Artesa shock pad refractor - Google Patents

Abstract

The present invention relates to a refractory trough shock pad, comprising: a body of refractory material capable of withstanding continuous contact with the molten steel during the complete cycle of use of a refractory tundish, the body comprising a base having a shock surface, an endless external side wall extending upwards from the impact surface, an upper surface essentially parallel to the impact surface and connected to the side wall, and defining a non-uniform opening therein, having the non-uniform opening a long dimension and a short dimension perpendicular to said long dimension, the upper surface having an inner annular portion essentially parallel to the impact surface, and the side wall having an inner face which remains essentially perpendicular to the impact surface , and wherein a substantially right angled corner is provided between the side wall and the surface It is provided with a shock angle, and a substantially right angled corner is provided between the side wall and the inner annular portion of the top surface so that the molten steel, which comes into contact with the shock surface, flows outward, then turn back inward and face up through the underside of the sidewall, and then flow out of the opening

Description

"REFRACTORY ARTESA SHOCK PAD" This invention relates to a refractory trough shock pad, that is, a pad of an erosion resistant material placed on the floor of a refractory tundish to receive the inlet stream of the molten metal cast into the tundish from a ladle . US Patent Number 5169591 discloses a shock pad for a refractory tundish for continuous steel casting comprising a base, a peripheral top surface and a discontinuous side wall extending between the base and the peripheral top surface, having the wall lateral a recessed internal surface that can be curvilinear. U.S. Patent Number 5358551 discloses a crash pad comprising a base, a side wall extending around the base, the side wall having an inner surface having a portion extending inwardly and upwardly. The inner surface can be concave. Although both types of shock pad mentioned above are designed to reduce turbulence in the refractory tundish, we have surprisingly discovered that improved turbulence reduction can be achieved by providing a shock pad with internal corners defined between its base, its peripheral wall and its upper surface. Therefore we have now found that it can be advantageous to provide these internal corners and that improvements in the reduction of surface turbulence, minimization of slag retention, prevention of disintegration of the refractory tundish flow cover, the reoxidation of the molten steel and ensuring an appropriate flow path of the steel within the refractory tundish can, of course, be achieved. Accordingly, in one aspect, the invention provides a refractory trough shock pad comprising a body of refractory material capable of resisting contact with the molten steel in a refractory tundish; the body comprises a base having a striking surface, an endless external side wall extending upwardly from the impact surface, an upper surface connected to the side wall and defining an opening therein, the upper surface having a inner annular portion essentially parallel to the impact surface and the side wall has an inner face which remains essentially perpendicular to the impact surface and wherein a corner at essentially right angle is provided between the side wall and the impact surface, and an The essentially right angle corner is provided between the side wall and the inner annular portion of the top surface. Molten steel entering through the opening and contacting the shock surface flows outward and then is rotated inwardly by the inner face of the side wall and then flows out of the opening. Preferably, the side wall is endless, that is, it extends continuously around the impact surface. Preferably, the opening is non-uniform, since it has a long dimension and a short dimension perpendicular to the long dimension. It can be, for example, rectangular or oval. The upper outer surface of the pad may also conveniently be parallel to the impact surface. The shock pads of the present invention uniformly disperse the flow of the input steel instead of just redirecting it. Since the flow of the steel can be dispersed through a larger area than if a circular configuration or other uniform configuration were used, the result is a flow directed towards the surface more evenly, while maintaining the benefits of reduced splashing and turbulence. Also, due to the non-uniform configuration of the shock pad, it has a larger "target" for the inlet steel than a pad of uniform configuration of similar width (e.g., circular or square) with the desired results obtained even when the steel stream is imperfectly aligned with the center of the shock pad. The invention is particularly useful for providing improved dwell time distribution parameters in cast molten steel. It can also be inexpensive due to its simplified internal chamber shapes and it can be of reduced overall size relative to known shock pads. The shock pads according to the present invention are formed of a refractory composition which is capable of withstanding continuous contact with the molten metal, in particular, the molten steel such as that which is used in continuous casting operations. Usually, a monolithic refractory of medium to high normal alumina with an alumina content within the range of about 55 percent to 85 percent by weight is, of course, desired. Where a basic refractory is preferred due to the chemistry of the steel, it is preferred that a magnesia-based monolithic refractory with MgO within the range of about 58 percent to 93 percent by weight be used. In another aspect, the invention provides a refractory tundish for retaining a volume of molten steel and having a floor and sidewalls that enclose a region of the crash and a drain, a crash pad of the present invention being provided on the floor of the refractory tundish in the region of shock. Modes of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a side cross-sectional view of a refractory tundish including a shock pad of the invention placed thereon; refractory trough floor; Figure 2 is a top plan view of the shock pad of Figure 1, illustrating where the cross section of Figure 1 is taken (along line 1 to 1); Figure 3 is a cross section through line 3 to 3 of Figure 2; and Figure 4 is an enlarged sectional view of a portion of the shock pad of Figure 3. In Figure 1, a conventional refractory trough 10 is shown and includes an inner liner 12 and a pair of well blocks or outlets. 14 to allow the molten metal (typically steel) from a bath 16 contained in the refractory tundish 10 to continuously exit the refractory tundish 10 and enter the molds (not shown) forming metal castings. As is also conventional, a bucket guard 18 or a device filled with a similar refractory tundish is placed above the refractory trough 10 and continuously directs a stream of molten metal towards the refractory tundish 10. The shock pad 20 of the refractory tundish constructed in accordance with the present invention, it is generally placed centrally on the floor 15 of the refractory tundish 10. As seen in Figures 1 to 4, the refractory trough shock pad 20 is preferably of rectangular configuration and placed with its longer sides parallel to the longitudinal axis of the refractory tundish. The pad includes a base 22 having a flat horizontal impact surface 24. The pad 20 further includes an endless annular external side wall 26, 40 having an inner wall face surface 28. The impact pad 20 also has a top surface 32 parallel to the impact surface 24 and connects to the side wall 26, 40 and defines a non-uniform opening 30 therein. By "non-uniform" it is meant that the opening 30 is neither circular nor square; instead it has a long dimension 30 '(see Figure 2) and a short dimension 30"essentially perpendicular to the long dimension 30'. As will be seen in all Figures 1 to 4, the inner face 28 of the side wall extends upward essentially at right angles to the impact surface 24 around the entire periphery thereof. The continuous nature of the inner surface 28 is possibly seen more clearly in Figure 2 having been shown dotted therein. As shown in Figures 3 and 4, the side wall 28 with the impact surface 24 and the lower portion 42 of the upper surface 32 provide two sharp corners 28A and 28B, respectively, whose corners also extend continuously around the interior of the shock pad. As seen in Figure 1, the outer side wall 26 can taper inward from the top surface 32 toward the base 22, defining the lugs 27 at the opposite ends. The lugs 27 facilitate the connection of the impact pad 20 with the base or floor 15 of the refractory trough when certain types of refractory tundish are used. Alternatively, the shock pad 20 can simply be mounted conventionally on the bottom of the refractory tundish. It will also be noted that the bottom portion of the upper surface 32 has annular portions 39, 42 (see Figure 3 thereof), which are parallel to the impact surface 24. This annular overbonding surface 42 facilitates the proper direction of the molten steel during filling of the refractory tundish 10. Note that the long dimension 30 'of the opening 30 is placed aligned with the long dimension of the refractory trough) the dimension between the outlets 14, as in Figure 1), while the short dimension 30 '' of the opening 30, is aligned with the short dimension of the refractory tundish 10. The external side wall portions 40 instead of tapering inwardly with the portions 26 of the side wall, preferably taper very slightly (e.g., from 2 ° to 5 °) outwards, as seen in the Figure 3. Alternatively, the straight sides can provide - Ji ¬ for both walls 2, 40 and the straight side walls 26 may or may not contain the lugs 27. The refractory material from which the impact pad 20 is manufactured must be capable of receiving continuous contact with the molten steel during the entire cycle. use of refractory tundish 10. Must have adequate refractoriness normally obtainable from a monolithic alumina refractory medium to medium high. For example, the alumina content within the scale of about 55 percent to 85 percent can be used. When a basic refractory is preferred due to steel chemistry, typically a monolithic refractory based on MgO with MgO within the range of about 58 to 93 percent is preferred. While it is preferred that the shock pad 20 be in a rectangular shape, as illustrated in Figures 1 to 4, non-uniform configurations may also be provided. For example, an oval shock pad or other multi-sided polygon configuration may be used as long as there is an opening with a long dimension that is aligned with the long dimension of the refractory trough 10, and with the short dimension aligned with the short dimension of the refractory tundish 10.

During use, the pad 20 of the refractory trough illustrated in Figure 1, the molten steel flowing in the path 34 from a site placed above the pad 20, impinges on the impact surface 24 and then moves radially outwardly as illustrated by the arrows 35. When the steel strikes the inside face 28 of the side wall, it is directed inward and then upwardly flowing as illustrated at 36 in Figure 1 and finally dispersed, usually , radially outward as indicated by arrows 37, 38 in Figure 1. This minimizes turbulence on the surface of bath 16 and helps direct slag and other impurities away from stream 34. It is not essential that corners shown in dotted line plan of Figure 2 are rounded as shown and the corners if desired, can be right angle. If desired, small corner fillets may be present at the right angle corners between the side wall and the impact surface and / or the inner annular portion of the top surface.

Claims (9)

R E I V I N D I C A C I O N E S:

1. A refractory trough shock pad (20) comprising a body of refractory material capable of resisting contact with the molten steel in a refractory tundish (10), the body comprises a base (22) having a surface (24) of shock, an external side wall (26, 40) extending upwards from the impact surface (24), an upper surface (32) connected to the side wall (26, 40) and defining an opening (30) in it, characterized in that the upper surface (32) has an inner annular portion (42) essentially parallel to the impact surface (24), and the side wall (26, 40) has an inner face (28) that remains essentially perpendicular to the impact surface (24), and wherein a corner is provided essentially at right angles (28A) between the side wall (28) and the impact surface (24), and a corner is provided essentially at a right angle between the side wall (28) and the internal annular portion (42) of the to upper surface.

A refractory trough shock pad according to claim 1, wherein the opening (30) has a long dimension (30 ') and a short dimension (30") perpendicular to the long dimension.

3. A refractory trough shock pad according to claim 2, wherein the opening (30) is rectangular or oval.

4. A refractory trough shock pad according to claim 1, 2 or 3, wherein the upper outer surface (32) of the pad is parallel to the impact surface (24).

5. A refractory trough shock pad according to any of the preceding claims, wherein the side wall (26, 40) is endless.

6. A refractory trough shock pad according to any of the preceding claims, wherein the pad (20) is a monolithic refractory having an alumina content of 55 percent to 85 percent by weight.

7. A refractory tundish shock pad according to any of claims 1 to 5, wherein the pad (20) is a monolithic refractory comprising magnesia and containing from 58 percent to 93 percent by weight of magnesia.

8. A refractory tundish (10) for retaining a volume of molten steel (16) and having a floor (15) and side walls (12) enclosing a shock region and a drain (14), wherein the refractory tundish (10) ) contains a shock pad (20) in accordance with that claimed in any of the foregoing claims, on the floor (15) of the shock region. A refractory tundish according to claim 8, wherein the impact pad (20) has an opening (30) for receiving a stream of molten metal, the opening (30) having a long dimension (30 '), and a short dimension (301') perpendicular to the long dimension (301), and the long dimension (30") of the opening (30) is aligned with the long dimension of the refractory tundish.