Title of Invention

AN OPEN MOUTHED CERAMIC BOX CONTAINER ADOPTED TO BE PLACED INTO A TUNDISH FOR EFFICIENT FLOW CONTROL OF STEEL IN A TUNDISH

Abstract

There is disclosed an open mouthed ceramic box container ( 1 ) adopted to be placed into the centre of a tundish used in the continuous casting of steel characterized by the following features: a) the container having two end walls ( 3a,3b ) and two side walls ( 2a,2b ) b) the said end walls being inclined with an obtuse angle towards the top while the two side walls are disposed vertically from the bottom, c) the top of the two side walls having equal lengths and greater than the equal lengths at the bottom, a) the end walls having same lengths both at the top and the bottom, e) there being provided a pair of drain out slots (7a1,7a2;7b1 7b2 ) on the side walls equi distant from the central axis and disposed in the same horizontal axis but in two different parallel vertical axes, and f) the said side wall also having through inclined holes (5a 1,5a2;5b1,,5b2), inclined upwardly and equi- distant from the central axis of the box.

Full Text

This invention relates to an open mouthed ceramic box container adopted to be placed into a tundish for efficient flow control of steel in a tundish. In other words this invention relates: to refractory shapes for efficient floe control of steel in tundish. BACKGROUND OF THE INVENTION: In continuous casting of steel, molten steel from the steel ladle is first poured into a tundish that is a distributor or buffer vessel that maintains an even and relatively uniform flow even as an empty ladle is replaced by the next full ladle. Some metallurgical operations are also carried out in the tundish. As the stream' of molten steel falls into the pool of metal in the tundish, it causes entertainment of gases, turbulent flow in the tundish and wave motion on the surface, phenomenon that hinder an efficient and uniform flow of metal from the tundish to the mould. Also, as the hot metal stream first hits the tundish, it tends to erode the tundish refractory lining. Further, the metal from the ladle contains some non-metallic inclusions that wfll go into the mould for casting, thus giving a defective product if not made to float up to the surface. Dams, weirs, striker pads and baffles have been used to reduce the problems associated with uncontrolled flow of metals. Frequently it leads to formation of dead zones that may lead to skull formation and other complications. Fitting of there? dams, weirs, pads etc. are cumbersome and time consuming and can lead to the tundish running cold. OBJECT OF INVENTION: After studying the steel flow patterns in the tundish, it was realized that the solution to all these problems can be found by designing a refractory structure that will protect the tundish refractories from the direct erosive action of the molten steel, will prevent turbulence created by the impact of the incoming stream from spreading out to length and breadth of the tundish, will direct streamlined flow of incoming metal towards the surface to facilitate floating of inclusions and lead to controlled flow without dead zones and still be quick and easy to install. BACKGROUND OF INVESTIGATIONS: We studied specific consideration of the striker pad and after conducting various experiments and trials, it is found that the objects of the invention can be achieved fay introducing a box type structure integrating the functions of striker pad, dam walls and slotted baffle, designed to fit snuggly into the tundish just under the incoming steam of molten steel This refractory -structure is made of MgO (90% to 95%) with impurities kept within specified limits (silica below 3%, Fe2O30.6 to CaO 0.6 to 1%) The side walls have a pair of notes each at an angle of - 30 ° to direct the flow of metal towards the surface for easy floatation of non metallic inclusions, 2 BRIEF DISCUSSION ON PRIOR ART. Our attention has been drawn to prior art European Patent No 1294508. This European Patent has equivalent US Patent no 7, 063,242 dt 20.06.2006 We have analysed and compared the Us Patent with our invention . For reasons stated below the prior art US Patent has nothing in common with our invention and the novelty of the invention is not affected by the prior art. APPLICANT'S INVENTION. US PATENT 7,063.242. a) Relates to a refractory box structure. a) Relates to a tundish device .b) Has two vertically disposed side walls b) Has a vertical wall between the end wails. and two inclined end walls . c) A unitary, integral single component c) A multi component non integral item item d) Both the side walls have special d) There is no such feature, features. e) Molten metal is directly fod on to the e) Molton metal is fed close to the bottom bottom floor from the top floor by a Special device f) The exiting metal is fed to a tundish f) The exiting metal is fed on to casting rolls. g) There is no partition wall g) There is a partition waH running close to the bottom wall. -3- h) Molten metal over flows from the h) Molten metal flows out from the bottom, top portions into a tundish. of the second chamber .i) The item is a ceramic structural i) The item is a tundish itself. component placed centrally inside a tundish j) The purpose for which it is used j) The purpose for which it is used is to is to feed a tundish. feed a casting roll system. k)The item is an open mouthed structure, k) The item is a closed structure. I) The item has a single chamber 1) The item has two chambers. m) The molten metal occupies a single m) The molten metal occupies two different level inside. levels in the two chambers. While these being some of the basic differences, there are many more structural as Well as functional differences between the applicant's invention and the prior art. -4- BRIEF STATEMENT OF THE INVENTION According to this invention there is provided An open mouthed ceramic box container ( 1 ) adopted to be placed into the centre of a tundish used in the continuous casting of steel characterized by the following features: a) the container having two end walls ( 3a,3b ) and two side walls ( 2a,2b ) b) the said end walls being inclined with an obtuse angle towards the top while the two side walls are disposed vertically from the bottom, c) the top of the two side walls having equal lengths and greater than the equal lengths at the bottom. d) the end walls having same lengths both at the top and the bottom, e) there being provided a pair of drain out slots (7al ,7a2;7bl 7b2 ) on the side walls equi distant from the central axis and disposed in the same horizontal axis but in two different parallel vertical axes, and f) the said side wall also having through inclined holes ( 5al,5a2;5bl,5b2 ), inclined upwardly and equi- distant from the central axis of the box, The said angle of inclination is 30 degrees, and the said inclined holes are at the same height from the bottom surface of the box and are disposed at the same horizontal axis but at two different parallel vertical axes. There are also provided additional holes ( 6al ,6a2;6a3,6a4 ) are provided at selected locations in the said side walls for the purposes of easy lifting and placing the box in a tundish or for lifting the same from the tundish as required -5- The refractory box is made principally of magnesia refractory material, and may have additional refractory material like Fe2O3, CaO, and SiO2 The refractory box has a bulk density of 2.77 gm / c.c and Cold Crushing Strength (CCS) at 1550.O.C of at least 290 Kilogram per cm 2.. It has an Orton Refractoriness of 38 /1835. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS. Figure 1 shows an isometric view of the box of this invention., Figure 2 shows a sectional view along the arrow A-A of figure 4, Figure 3 shows the view along the arrow B-B of figure 2., Figure 4 shows a plan view and Figure 5 shows the view at 'X 'of figure 4. DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS. Referring to figure 1 it will be seen that the refractory box 1 is made of two side walls 2a, 2b of identical dimensions disposed vertically from the bottom. The box has two end walls 3a, 3b disposed in an inclined manner from the bottom. The end wall 3a joins the extreme left side ends of the sidewalls 2a, 2b.. Similarly, the end wall 3b joins the extreme right side ends of the side walls 2a, 2b. It will thus be appreciated that the lengths at the top ends of the side walls 2a, 2b are the same .Similarly the lengths of the side walls 2a, 2b at the bottom end are also same. But the important difference is that the length at the top end is longer than the length at the bottom.. Thus both the left ends 4al, 4a2 and both the right side ends 4bl, 4b2 are tapered towards their respective lower ends. 4 It will further be appreciated that both the end walls 3a and 3b are identical in all respect*. The lengths at their top end and the length at the bottom ends are same and are inclinedly disposed towards the ends of the side walls This unique consumption has been arrived at after much research, design and-experiment so that this box conveniently sits in the tundish Further, it will be seen from figure 1, that each side wall 2a and 2b has further identical constructional features. There are a pair of inclined holes 5a1, 5a2 and 5b1 and 5b2 on the side walls 2a, 2b. The inclination is at its lowest at the interior side and goes upwards at the outer side. The inclination is preferably 30 ° though other angles are not ruled out. ' , Both the pair of holes 5a, 5a2 and 5b1 and 5b2 are provided at the same height from the base or ¦bottom wall. Thus, the holes 5a1, 5a2 5b1, 5b2 are at the same horizontal plan but are at two different vertical plans parallel to one another. These holes help in improving the floatation of non-metallic impurities in the molten bath when it is poured into the box. In order to facilitate lifting and or placing of the box in the tundish, there are provided a pair of small holes 6a 1, 6a2 and 6b 1, 6b2 respectively as suitable locations on the side walls 2a and 2b. The entire structure and the location of the various holes on the side walls are ingenious Furthermore, it will be seen that both the side walls of the box are provided with two drain out sots 7a 1 , 7a2 and 7b1, 7b2 as seen in figure 1. These holes are preferably located at near the four bottom corners of the two side walls. These slots help in draining out the molten material into the tundish. The molten material thus, does not directly hit the tundish and smoothly flows though the drain out holes, which result in longer life of the tundish. From figures 2, 3, 4 and 5. the same details can be seen in other views. 7 The dimensions mentioned here are for a trial tundish and will change with the design and dimensions of the tundish' DESCRIPTION OF THE INVENTION: A box type refractory structure as shown in the drawing is placed at the centre of the tundish, such that it will receive the molten steel stream during its flow from the lade to the tundish). The sloping end walls of the box fit against the side walls of the tundish. The vertical side wads of the box run across the width of the tundish, one on each side of its centre line. The dimensions of the box will be altered to fit those of the tundish in a manner described above. Advantages of the box type structure as described above are: 1. Ease of handling. The structure can be lifted and moved for quick placement and removal thus reducing the downtime and increasing the productivity. 2. Floatation of non metallic to the surface, improving the quality of steel. 3. Controlled flow of molten metal in tundish and hence from tundish to mould. 4. Elimination of dead zones in tundish. 5. Minimization of entrapment of gases. 6. Homogenization of steel composition. These advantages have been confirmed in controlled trial runs. 8 PRODUCT: TATA M DAM TYPE: BASIC CASTABLE APPLICATION TEMPERATURE: 1750°C 9 Packaging: In pallets (Water proof) Storage life: 6 months. Delivery state: Fired W We Claim, 1). An open mouthed ceramic box container ( 1 ) adopted to be placed into the centre of a tundish used in the continuous casting of steel characterized by the following features: a) the container having two end walls ( 3a,3b ) and two side walls (2a,2b) ,b) the said end walls being inclined with an obtuse angle towards the top while the two side walls are disposed vertically from the bottom, c) the top of the two side walls having equal lengths and greater man the equal lengths at the bottom, d) the end walls having same lengths both at the top and the bottom, e) there being provided a pair of drain out slots (7al,7a2;7bl 7b2 ) on the side walls equi distant from the central axis and disposed in the same horizontal axis but in two different parallel vertical axes, and f) the said side wall also having through inclined holes ( 5al,5a2;5bl,5b2 ), inclined upwardly and equi- distant from the central axis of the box, 2) An open mouthed ceramic box container as claimed in claim 1 wherein the said angle of inclination is 30 degrees. 3) An open mouthed ceramic box container as claimed in claims 1 and 1, wherein the said inclined holes are at the same height from the bottom surface of the box and are disposed at the same horizontal axis but at two different parallel vertical axes. -11- 4) An open mouthed ceramic box container as claimed in claims 1 to 3, wherein additional holes ( 6al ,6a2;6a3,6a4 ) are provided at selected locations in the said side walls for the purposes of easy lifting and placing the box in a tundish or for lifting the same from the tundish as required .5) An open mouthed ceramic box container as claimed in claims 1 to 4, wherein the box is made of magnesia refractory material as herein described. 6) An open mouthed ceramic box container substantially as herein described with -12- reference to figures 1 to 5 of the accompanying drawings. There is disclosed an open mouthed ceramic box container ( 1 ) adopted to be placed into the centre of a tundish used in the continuous casting of steel characterized by the following features: a) the container having two end walls ( 3a,3b ) and two side walls ( 2a,2b ) b) the said end walls being inclined with an obtuse angle towards the top while the two side walls are disposed vertically from the bottom, c) the top of the two side walls having equal lengths and greater than the equal lengths at the bottom, a) the end walls having same lengths both at the top and the bottom, e) there being provided a pair of drain out slots (7a1,7a2;7b1 7b2 ) on the side walls equi distant from the central axis and disposed in the same horizontal axis but in two different parallel vertical axes, and f) the said side wall also having through inclined holes (5a 1,5a2;5b1,,5b2), inclined upwardly and equi- distant from the central axis of the box.

Documents:

00643-kol-2004-abstract.pdf

00643-kol-2004-claims.pdf

00643-kol-2004-correspondence.pdf

00643-kol-2004-description(complete).pdf

00643-kol-2004-drawings.pdf

00643-kol-2004-form-1.pdf

00643-kol-2004-form-18.pdf

00643-kol-2004-form-2.pdf

00643-kol-2004-form-3.pdf

00643-kol-2004-g.p.a.pdf

00643-kol-2004-letters patent.pdf

00643-kol-2004-p.a.pdf

643-kol-2004-granted-abstract.pdf

643-kol-2004-granted-claims.pdf

643-kol-2004-granted-description (complete).pdf

643-kol-2004-granted-drawings.pdf

643-kol-2004-granted-form 2.pdf

643-kol-2004-granted-specification.pdf