SLIDE PLATE FOR USE IN AN APPARATUS FOR CONTROLLING AMOUNT OF TEEMING MOLTEN METAL

Abstract: This invention intends to provide a molten metal pouring amount control apparatus in which a sliding resistance of a slide frame is small and a pressing force around a nozzle hole is stabilized so that there is no fear that any trouble such as a molten metal leakage occurs and further, a structure thereof is simple and maintenance cost is low. More specifically, this invention provides a molten metal pouring amount control apparatus for adjusting an opening of a nozzle hole in a fixed plate and an opening of a nozzle hole in a sliding plate by sliding a slide frame by means of a driving means, the control apparatus further comprising guide units each including a plurality of steel balls arranged in line between the slide frame and springs, the guide units being provided on both sides of the sliding plate.

Description: The present invention relates generally to molten pouring metal amount control apparatus which is attached to the bottom of a molten metal container such as a ladle, and is concerned specifically with sliding plates for incorporating in such apparatus for controlling the size of a nozzle hole between the sliding plate and a fixed plate so as to control the rate of pouring of molten metal. Molten metal pouring amount control apparatus usually comprises a fixed plate made of a refractory material detachably attached to a base plate fixed on a ladle or the like having a nozzle hole and a sliding plate made of refractory material detachably attached to a slide frame and also having a nozzle hole. By sliding the slide frame along the base plate, the proportions of the nozzle holes in the fixed plate and the sliding plate which are in alignment are adjusted so as to control the pouring rate of the molten metal. There is however, a risk that molten metal will leak between the fixed and sliding plates, at least under certain conditions. One example of a known sliding plate for use in pouring amount control apparatus is of polygonal shape and is shown in plan view and side sectional view in Fig. 9 and Fig. 10, respectively. A second example is an oval plate 113 whose plan view and side sectional view are shown in Figs. 11 and 12, respectively. Reference numerals 112, 114 denote nozzle holes of the respective plates. In use, these plates are overlaid and one of them is slid as a sliding plate so as to control opening/closing of the nozzle hole to adjust the flow rate of molten metal. US-A-5139237 discloses a sliding plate whose shape, in plan, has two part-circular ends of different diameters and two straight sides connecting the part-circular ends. If the diameter of the nozzle hole is a, a position spaced from the centre point of the nozzle hole by a distance s (=2a+β) is Y, the distance from the edge of the nozzle hole to the nearest edge of the plate is d, and the distance from a virtual circle of diameter a around the position Y up to the nearest edge of the plate is d 2 , then the pad ratio α 1 = d 1 /a is about 1.6 and the pad ratio α 2 = d2/a is about 0.8. From previous operational experience over a long time, most molten metal leakage occur when the nozzle is located in the open position and hardly occurs in the closed position. The reason is that although a function for controlling the flow amount of the molten metal is necessary at the open position of the nozzle, the function necessary at the closed position is only to stop the flow of the molten metal. However, conventionally, the shape at the open position or closed position of the nozzle hole has not been determined sufficiently reasonably considering its function and economic performance. The sliding plate is thus melted and eroded by the passage of high temperature molten metal and the like. Therefore, there is the fear that the molten metal and the like may leak if it is used too frequently. Thus, the sliding plate is replaced every few charges and handled as a consumable product. However, because this sliding plate is made of refractory material like an expensive brick, the running cost is high and this is an impediment to the reduction of cost. It is thus the object of the present invention to form a sliding plate in an economic shape within a range which does not generate a leakage of the molten metal whilst minimising the unit price thereby achieving a reduction of long term cost. According to the present invention a sliding plate has the features set forth in Claim 1. It advantageously also has the features of the dependent claims. Consequently, not only can the sliding plate be formed in an economic shape within the range in which no leakage of the molten metal occurs, but also the plate can be fixed more easily by using the straight sides of the polygonal shape. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a pouring amount control apparatus in which the sliding plate in accordance with the invention may be used with the door open; Fig. 2 is a view similar to figure 1 with the door closed; Fig. 3 is a longitudinal sectional view showing the apparatus attached to the bottom of a molten metal container; Fig.4 is a bottom view of the apparatus with the door open; Fig. 5 is a plan view showing one embodiment of a sliding plate of the present invention; Fig. 6 is a side sectional view of the plate of Fig. 5; Fig. 7 is a graph showing the relationship between pad ratio (a 1 , a 2 ) and the molten steel leakage generation index; Fig. 8 is a plan view showing another embodiment of the sliding plate of the present invention; Fig. 9 is a plan view showing a conventional sliding plate; Fig. 10 is a side sectional view of the plate of Fig. 9; Fig. 11 is a plan view showing another conventional sliding plate; and Fig. 12 is a side sectional view of the plate of Fig. 11. In Figures 1 to 4, reference numeral 2 denotes a base plate fixed to a bottom 60 of a molten metal container (hereinafter referred to as ladle) and it has a concave portion 3. This concave portion 3 contains a fixing plate 4 made of refractory product and having a nozzle hole 5 and is fixed with a fixing metal 6. Reference numerals 7a, 7b denote a cutout portion in which part of a clamp mounting metal (which will be described later) is to be inserted. Reference numeral 8 denotes a bracket extending to one side, on which a hydraulic cylinder 9 which is a driving means for a slide frame described later is mounted. An fitting portion 10 is provided at a tip of an actuator thereof. Reference numerals 11a, 11b denote a swing arm provided on a side wall perpendicular to the bracket 8. Reference numeral 21 denotes a box like frame mounted to the base plate 2 through hinges 15 such that it can be opened or closed. An opening portion 22 is provided in a side wall (on the side of the bracket 8 of the base plate 2). Further, a vertical wall 23 is provided on each of both side walls perpendicular to this side wall such that they stand up from each side wall. This vertical side wall has a clamp insertion hole 24. Reference numeral 25 denotes a slide frame incorporated in the frame 21 and a concave portion 26 is provided in a top surface thereof. This concave portion 26 accommodates a sliding plate 27 made of refractory product having a nozzle hole 28 and is fixed with a fixing metal 29. Free surfaces of the fixing plate 4 and sliding plate 27 are located slightly higher than the surfaces of the base plate 2 and slide frame 25 respectively, for example, about 5 mm higher. Reference numeral 30 denotes an engaging portion which is provided in the slide frame 25 on the side of the opening portion 22 of the frame 21 and which the engaging portion of the hydraulic cylinder 9 engages. Reference numeral 31 denotes a liner (cam) which has an inclined face on one side thereof and is provided near the vertical wall 23 of the frame 21 and on a top face of the slide frame 25. Reference numeral 35 denotes a guide unit provided below the slide frame 25 and on both sides of the concave portion 26. Reference numeral 45 denotes a spring seat disposed between the frame 21 and slide frame 25 vertically movably, reference numeral 46 denotes a plurality of spring guides provided on a bottom of the frame 21 such that they stand up, and reference numeral 47 denotes a coil spring mounted over the spring guide 46 between the frame 21 and spring seat 45. The upper lace 40 of the guide unit 35 is fixed on a bottom surface of the slide frame 25 and the lower lace 42 is fixed on a top surface of the spring seat 45 so that the balls accommodated by the retainer 37 are nipped. The coil springs 47 urges the slide frame 25 upward through the spring seat 45 and guide unit 35 so as to press-fit the sliding plate 27 to the fixed plate 4. A door 20 is comprised of the frame 21, slide frame 25, guide unit 35 and the like. Reference numeral 50 denotes a clamp mounting metal, which is comprised of substantially inverted L shaped side plates 51a, 51b and a mounting plate 52 fixed between the side plates 51a and 51b. The mounting plate 52 has clamp guide holes 53 of the same size as the clamp insertion hole 23 provided in the frame 21. The mounting plate 52 of the clamp mounting metal 50 is brought into contact with the side plate of the frame 21 and the clamp guide holes are matched with the clamp insertion holes 23. Then, screws are inserted through screw insertion holes 54 and driven into threaded holes provided in the side wall. Reference numeral 55 denotes a clamp which is to be inserted into the clamp insertion hole 23 through the clamp guide hole 53 and has a handle 56. Although Figs. 2, 3 show the clamp mounting metal 50 and clamp 55 on only one side, they are provided on the other side also. Reference numeral 61 denotes a upper nozzle which has a nozzle hole 62 and is attached to the bottom of the ladle or the like and reference numeral 63 denotes a collector nozzle which has a nozzle hole 64 and is attached to the side frame 25. Figures 5 and 6 show a sliding plate in accordance with the invention which is particularly suitable for the use in the pouring amount control apparatus described above. This sliding plate can be used for not only the aforementioned pouring amount control apparatus but also a pouring amount control apparatus of other type. Assuming that the centre position of a nozzle hole 72 provided in the plate 71 is X, the diameter of the nozzle hole 72 is a, a distance from an edge of the nozzle hole 72 up to the nearest edge of the plate 71 is d 1 , a position apart from the centre position X of the nozzle hole 72 by a distance S (=2a+β) is Y, and a distance from a virtual circle 73 of a diameter a around the position Y up to the nearest edge of the plate is d 2 , in the sliding plate of the present invention, the pad ratio α 1 = d 1 /a is between 0.8 and 1.2, the pad ratio α 2 = d 2 /a is between 0.4 and 0.6 and the safety distance β is 0-60 mm. Its outer shape is polygonal, as shown in Fig, 5. The distance S between the positions X and Y is the slide stroke of the sliding plate. (a) Pad ratio α 1 Although increasing the ratio α 1 eliminates molten metal leakage, the plate is enlarged and economic efficiency is thus lost. On the other hand, if the ratio α 1 is reduced, although the plate cost drops, the frequency of molten metal leakage increases. If the ratio α 1 drops below 0.8 as shown in Fig. 7, the frequency of the molten metal leakage increases. (b) Pad ratio α 2 If the ratio a 2 is enlarged, the economic efficiency is lost and if the ratio α 2 is reduced too much, the frequency of molten metal leakage increases only if the flow of the molten metal is stopped. If the ratio α 2 drops below 0.4 as shown in Fig. 7, the frequency of the molten metal leakage increases. (c) Stroke S The moving distance of the plate is at least twice the diameter of the nozzle hole 72. (d) Safety distance β Although this ensures a stroke range for the plate 71 in which it operates securely, if this is too large, the plate is enlarged thereby increasing the cost. Thus, the safety distance is 0-60mm. In Fig. 5, d 1 /a =1, d 2 = d 1 /2 and d 2 /a = 0.5. Further, five sides of an octagon touching internally the virtual circle 74 of diameter (a+2d 1 ) around the position X and three sides of an octagon touching internally a virtual circle 75 of diameter (a+2d 2 ) around the position Y are connected with straight lines A, B so as to produce a plate of decagonal shape. Although the pad ratio α 1 = d 1 /a is 1.0, this only has to be more than 0.8 to prevent molten metal leakage and from the economic stand point, it needs to be less than 1.2. Further, although in Fig. 5, the pad ratio α 2 =d 2 /a is 0.5, this only has to be more than 0.4 to prevent molten metal leakage as shown in Fig. 7, and from the standpoint of economic performance, it must be less than α 1 and have a value from 0.4 to 0.6. Although in Fig. 5, the sliding plate is of decagonal shape plate, any polygonal is permitted as long as the sliding plate can be fixed. The corners of that polygon may be arcuate as shown in Fig. 8. Although in this example, the plate thickness is constant as shown in Fig. 6, it is permissible to construct the plate so that the thickness of the portion near the nozzle hole, particularly around the nozzle hole, is greater than that of the remainder.

Claims: A sliding plate having a nozzle hole (72) for use in a molten metal pouring amount control apparatus, for controlling the pouring amount of molten metal, wherein, assuming the center position of the nozzle hole (72) is X, the diameter of the nozzle hole (72) is a, the distance from the edge of the nozzle hole (72) to the nearest edge of the plate is d 1 , a position spaced from the center position X of the nozzle hole (72) by a distance S (=2 a + β) is Y, and the distance from a virtual circle (73) of diameter a around the position Y to the nearest edge of the plate is d 2 , then the pad ratio α 1 = d 1 /a is in the range between 0.8 and 1.2, the pad ratio α 2 = d 2 /a is in the range between 0.4 and 0.6, a safety distance β is set in the range of 0-60 mm, and the external shape of the plate is a third polygon which includes part of a first polygon having a virtual inscribed circle (74) of diameter (a+2d 1 ) around the position X and part of a second polygon having a virtual inscribed circle (75) of diameter (a+2d 2 ) around the position Y. A sliding plate according to Claim 1 wherein each of said first and second polygons is an octagon, and said third polygon is a decagon constituted by five sides of the first polygon, three sides of the second polygon and two sides (A, B) connecting the five sides and the three sides to each other. A sliding plate according to Claims 1 or 2 wherein d 2 = d 1 /2. A sliding plate according to any one of Claims 1 to 3, wherein the thickness of a portion around said nozzle hole (72) is larger than the thickness of the other portions.

Inventors: TSURU MASAHIRO, YAMAMOTO HIRONORI, TSURU, MASAHIRO, YAMAMOTO, HIRONORI, TSURU, Masahiro, Nippon Rotary Nozzle Co., Ltd.
Applicants: JFE ENG CORP, JFE MECHANICAL CO LTD, NIPPON ROTARY NOZZLE CO LTD, TOKYO YOGYO KK, JFE ENGINEERING CORPORATION, JFE MECHANICAL CO., LTD., NIPPON ROTARY NOZZLE CO.,LTD., TOKYO YOGYO KABUSHIKI KAISHA
Application year: 1998
Main classification: B22D41
IPC codes: B22D41, B22D11, B22D37