APPARATUS FOR CONTROLLING FLOW RATE OF MOLTEN METAL

Abstract: This invention relates to an apparatus for controlling a flow rate of a molten metal, capable of being set at a bottom or side portion of a molten metal container and consisting of a rotary nozzle of various shapes, a nozzle receiving brick and a sleeve, or a rotary nozzle, and a nozzle receiving brick. At least one of the nozzle receiving brick and sleeve is provided with at least one recess or opening, and the surface of the opened end portion of the rotary nozzle, which has at least one through bore, is in close contact with and supported on the inner circumferential surface of the nozzle receiving brick of sleeve so that the nozzle can be turned, a rotary mechanism being provided to the rotary nozzle.

Description: This invention relates to a discharge assembly for molten metal, which is used when molten metal is poured from a molten metal vessel such as ladle or tundish. BACKGROUND TECHNIQUE A nozzle stopper system and a slide valve (sliding nozzle) system are well known as discharge regulating mechanism for pouring a molten metal from a molten metal vessel. It is also known that such conventional systems have the following drawbacks. 1. Nozzle stopper system 1) Since a nozzle stopper 1 having approximately same in length as the molten metal vessel is required, the refractory costs are high. 2) As will be seen from Fig. 15 (showing a relationship of the stroke and the opening area between the slide valve and the nozzle stopper), the discharge rate greatly varies with only a slight movement of a nozzle stopper 1 so that this system is inferior in discharge regulation. 3) Since the nozzle stopper 1 is immersed in the molten metal, there occur troubles such that the nozzle stopper is broken due to melting-down or heat spalling thereby disabling the discharge regulation. 2. Slide valve system 1) In the case of a ladle, it takes a time of about ten minutes to several hours for the period from receiving molten metal in a ladle to pouring (hereinafter called casting) the molten metal because of component control, temperature control, etc. of the molten metal. This necessitated filling the interior of a nozzle 2 with a filler such as sand to prevent molten metal from solidification within the nozzle thereby lowering the working efficiency. The filler is based on the idea that in case the slide valve is opened the filler first flows out and then the molten metal flows out so that the nozzle naturally opens. However, the molten metal can permeate into the filler and be solidified there and the nozzle sometimes does not naturally open. This necessitates the nozzle 2 to be forcedly open by an oxygen lance thus compelling the operator to perform dangerous work. 2) In the case of tundish, one cannot use a filler or the like in the light of quality of molten metal, and it is necessary to apply refractory, steel pipe or the like to the upper outer periphery of the nozzle so that the nozzle may open after the molten metal has accumulated in a predetermined amount. This causes unfavorable workability and high cost. 3) Again in the case of tundish, there is a method of preventing the molten metal within the nozzle from solidification by injecting an inert gas from a fixed plate 3 or a slide plate 4 as shown in Fig. 16 instead of using refractory or steel pipe. However, in such a case the mechanism of introducing the inert gas becomes complicated and the costs are high. Further, even in the method (c) above, 100% success would not be expected and the molten metal within the nozzle sometimes solidifies thereby disabling casting from even starting.Furthermore, even when an immersion nozzle is replaced while casting, the nozzle is closed, and therefore the same inconvenience as above occurs. 4) The nozzle is can occasionally be opened fully while casting due to erroneous operation or some necessity. However, since the molten metal solidifies within the nozzle if the nozzle is retained fully open for a long period of time, a forced opening of the nozzle becomes necessary. 5) Since this system has a number of connecting portions and there is a great risk of air entering from the exterior of the refractory, it is greatly possible that the quality of the product is adversely affected. The Austrian Patent AT-A-165 292 discloses a nozzle arrangement for discharging molten metal from a vessel comprising a cone-shaped rotating nozzle, which has a centrally located flow channel therein. The flow channel makes a turn within the nozzle and ends in an opening on the mantle surface of the cone cap of the nozzle. The nozzle can be rotated such that the nozzle opening aligns with an opening in a nozzle brick arranged above the cone cap. The European Patent Application EP-A-0 310 296 discloses a rotary pouring nozzle comprising a stationary component and a rotatable component sealingly engaged therein. The stationary component has a flow aperture directed laterally off the rotational axis of the rotatable component with which a nozzle outlet in the rotatable component can be moved into and out of register by rotation of the rotatable component. The known pouring nozzle further comprises an interlocking connection inside of the stationary component which retains the stationary and rotatable components together in their working relationship. Moreover another rotary valve as shown in Fig. 17 is a new modern technique. This system is characterized in that it consists of a rotor 20, a dome nozzle 21 and a drive mechanism 20a, the dome nozzle 21 is fixed to a tundish 23 and the rotor 20 is turned to permit the discharge flow of the molten metal to be regulated. However, even this system has the following drawbacks. 1) Since the rotor 20 is immersed in the molten metal, defects occur in that the rotor is broken due to melting-down or heat spalling, and the discharge regulation becomes disabled occasionally. 2) Since the rotor 20 is longer than the height of tundish 23, the system is costly. 3) In the initial state of casting, a nozzle 22 is fully opened, the molten metal is poured into the tundish 23, the nozzle 22 is opened after the molten metal has been accumulated in a predetermined amount, and then the casting work is started. However, the nozzle 22 itself cannot be made too large for the following reasons, so that the molten metal solidifies because of the lowered temperature of the molten metal within the nozzle 22 thereby sometimes disabling the casting from the start. To make the nozzle 22 large-sized results in that the rotor 20, the dome nozzle 21 and other related members also need to be large-sized, which leads to an increase of cost and problematical workability. Thus, to make the nozzle 22 large-sized is naturally limited to a certain extent.On the other hand, in an emergency such as incorrect operation during the casting work or overflow of the molten metal within the mold, the nozzle 22 may occasionally be opened fully. In such a case the molten metal within the nozzle 22 solidifies as described above and it becomes impossible to restart the casting. 4) Since the rotor 20 is large and heavy, its handling and setting work is inconvenient. DISCLOSURE OF THE INVENTION The present invention provides a discharge assembly for molten metal as defined in claim 1, the preamble of which is based upon document DE-A-2 836 813. Embodiments of the invention are given in claims 2 to 6. The present regulator can be disposed at the bottom portion or side portion of a molten metal vessel. The regulator consists of a rotary nozzle, a nozzle carrying brick and a sleeve or of a rotary nozzle and a nozzle carrying brick. At least one recessed notch or opening is provided in at least either one of said nozzle carrying brick and said sleeve. The nozzle opening of the rotary nozzle, which pierces through at least one nozzle hole, is supported slidably to and in close contact with the inner peripheral surface of said nozzle carrying brick or said sleeve. The rotary nozzle is equipped with a rotary drive mechanism mounted in such a manner that the upper portion of said rotary nozzle is brought into contact with the molten metal. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 to 14 are schematic views showing embodiments of the apparatus of the invention; Fig. 15 is a graph showing a relationship of stroke and opening area between the slide valve system and the nozzle stopper system; and Figs. 16 and 17 are schematic views of known nozzle arrangements. BEST EMBODIMENT FOR CARRYING OUT THE INVENTION The invention will now be described more in detail, by way of some embodiments, with reference to the accompanying drawings. As shown in Fig. 1, a sleeve 7 is fixed with mortar to a nozzle carrying brick 6 fixed also with mortar at the bottom portion or the side portion of a molten metal vessel 5, a rotary nozzle 8 is in close contact with the tapered portion or straight portion of the inner surface of said sleeve 7 and rotatably supported by a rotation controlling case 10 (hereinafter called case), and the discharge of molten metal is regulated by rotating the rotary nozzle 8. The embodiments will be described more in detail with reference to Figs. 1 to 5. As will be seen from these figures, the rotary nozzle 8 is a shape of truncated cone, and as shown in Fig. 5, its lower portion is provided with two or more driving flat surfaces parallel to the axis of rotation of the rotary nozzle 8, an L-shaped nozzle hole 9 is provided from the tapered portion of the side surface of the sleeve toward the lower portion, and a recessed notch 25 is provided in the sleeve 7 and the nozzle carrying brick 6 so that the molten metal may flow in from said nozzle hole 9 of the tapered portion. As shown in Figs. 3 and 4, said recessed notch is provided at least one in the zone from the upper surfaces of the nozzle carrying brick 6 and the sleeve 7 to the side surfaces thereof, and it refers to a notched portion irrespective of straight line cut or curved line cut and irrespective of shape. The sleeve 7 is fixed to the nozzle carrying brick 6 with mortar so as not to be rotable. In order that the rotary nozzle 8 and the sleeve 7 are brought into close contact so that molten metal may not enter into their close contact surfaces, and that the rotary nozzle 8 is rotatably supported, said rotary nozzle 8 is supported by a case 10. As shown in Fig. 11, the outer periphery of said case 10 is provided with a transmission means (as shown Fig. 11) such a gear or link to transmit turning force, and said transmission means is driven by a driving means (not shown) such as electric motor, oil pressure motor or oil pressure cylinder thereby to regulate the discharge flow of the molten metal. The invention will then be described in respect of the using method based on the regulation mechanism thus constructed. Firstly, the rotary nozzle 8 is turned to move the nozzle hole 9 to a place other than the recessed notch 25 of the sleeve 7 and nozzle carrying brick 6 to bring the nozzle hole 9 to a blocked state, when molten metal is received into a vessel. Casting of molten metal is effected by turning the rotary nozzle 8 to bring the nozzle hole 9 into an engagement with the recessed notch 25 of the sleeve 7 and nozzle carrying brick 6. As shown in Fig. 4, the discharge of the molten metal is regulated by turning the rotary nozzle 8 to block (squeeze) the nozzle hole 9 by the edge of the recessed notch 25 of the sleeve 7. Further, such a discharge regulation can be carried out at two places of A portion and B portion in Fig. 2. Though the invention has been described by way of one embodiment it may be possible that the dimension of the recessed notch of the sleeve 7 and nozzle carrying brick 6 is made to such an extent that the nozzle hole 9 of the rotary nozzle 8 may not be blocked, to be sufficiently large-sized. It is also possible that said nozzle hole 9 and said recessed notch 25 need not be provided at singular places but at several places. The outer shape of the rotary nozzle 8 may be, in its outer periphery, straight line 8a (column) or reversely tapered line 8b (upturned truncated cone), as shown in Figs. 6 and 7. The shape of the nozzle hole 9 may be straightly piercing hole 9a obliquely from the tapered surface as shown in Fig. 8 or elliptic 9b in its sectional view as shown in Fig. 9a and Fig. 9b. The combination of the rotary nozzle 8 with the sleeve 7 and the nozzle carrying brick 6 may be replaced even by a combination of the rotary nozzle 8 with the nozzle carrying brick 6c as shown in Fig. 10. One embodiment of the device of supporting said rotary nozzle 8 is shown in Fig. 11. The case 10 retained at the flat surface in the lower portion of the rotary nozzle 8 to impart rotation to the rotary nozzle, is rotatably retained by an outer case 11, and it is secured by a bolt and nut 12 to a fixed base 15 welded or bolted to the molten metal vessel 5. Gearing is provided in the outer periphery of the case 10, a reduction gearing 13 is provided between the case 10 and the outer case 11, a worm gearing 14 is provided further outside the reduction gearing 13, and the worm gearing 14 is provided with a drive source (not shown) such as electric motor or oil pressure motor whereby the rotation of the rotary nozzle 8 is controlled. Then, an embodiment of incorporating an intermediate nozzle 16 is described with reference to Fig. 13. The rotary nozzle 8, the sleeve 7 and the nozzle carrying brick 6 are the same as those illustrated in Fig. 1, but in this mechanism an intermediate nozzle 16 is provided beneath the rotary nozzle 8. Said intermediate nozzle 16 is in close contact with the rotary nozzle 8 by means of a case 17, and it is fixed so that it may move even if the rotary nozzle 8 turns. The contact surfaces of the intermediate nozzle 16 and the rotary nozzle 8 may be formed plane or in spherical surfaces 8e, 16a or an engaging shape of two or more convexes and concaves 8f, 16b as shown in Figs. 13 and 14. Additionally, this mechanism is effective when a lower nozzle such as immersion nozzle or long nozzle is used. According to the discharge assembly of the present invention, the problems encountered in known techniques are all solved and it has the following merits. (1) Since molten metal does not enter into the nozzle hole 9 at the start of casting, not only a filler is unnecessary but also injecting of an inert gas is not required. Cost is therefore low and a stable operation becomes possible. (2) Even when an immersion nozzle or the like is replaced while casting the molten metal does not enter into the nozzle hole 9 when the nozzle is closed, and therefore, the same effect as in (1) above is produced. (3) The entire mechanism has less connection portions than the slide valve system, so that the external air is less inhaled thereby improving the quality of the product. (4) Since the regulator is compact and refractory is used in a smaller amount the cost becomes low. Further, refractory members can be easily replaced. (5) Since the discharge flow can be regulated at two places of A portion and B portion as shown in Fig. 2, the discharge regulating property and the life of the regulator are superior to conventional techniques. The present invention finds industrial application as a discharge regulating system when molten metal is poured from a molten metal vessel.

Claims: A discharge assembly comprising a molten metal vessel (5) and a regulator for molten metal mounted in a bottom wall or a side wall of the vessel (5), consisting of (a) a rotary nozzle (8), a nozzle carrying brick (6) and a sleeve (7) or (b) a rotary nozzle (8) and a nozzle carrying brick (6c) whereby said rotary nozzle (8) comprises a nozzle opening (9), which pierces through at least one nozzle hole, is supported slidable to and in close contact with the inner peripheral surface of the nozzle carrying brick (6, 6c) or the sleeve (7), and said rotary nozzle (8) is equipped with a rotary drive mechanism (13, 14), and wherein the internal end surfaces of each of said rotary nozzle (8), carrying brick (6, 6c) and sleeve (7) are in flush arrangement with the inner peripheral surface of the bottom portion or the side portion of the molten metal vessel (5), characterized in that at least one recessed notch (25) opening directly into the interior of the vessel (5) is provided in at least either one of the nozzle carrying brick (6, 6c) and the sleeve (7), whereby in order to discharge the molten metal from the vessel, said recessed notch (25) is brought into engagement with said nozzle opening (9) by turning the rotary nozzle (8). The discharge assembly according to claim 1, characterized in that the rotary nozzle (8) is of truncated cone shape, reversed truncated cone shape or column shape. The discharge assembly according to claim 1, or 2, characterized in that the lateral section of the nozzle hole (9) of the rotary nozzle (8) is of a circular (9a) or an elliptic shape (9b). The discharge assembly according to any of claims 1 to 3, characterized in that an intermediate nozzle (16) is fixed in close contact with the lower end surface of the rotary nozzle (8). The discharge assembly according to claim 4, characterized in that the engaging surfaces of the rotary nozzle (8) and the intermediate nozzle (16) are either spheric (8e, 16a) or uneven and irregular (8f, 16b). The discharge assembly according to any of claims 1 to 5, characterized in that the rotary nozzle (8) is supported by a rotation controlling case (10).

Inventors: OSADA MOTOTSUGU, OTSUKA TAKASHI, SHIGETA YOSHIFUMI, TANIGUCHI TADAO, YAMAMOTO KENJI, OSADA, MOTOTSUGU, OTSUKA, TAKASHI, SHIGETA, YOSHIFUMI, TANIGUCHI, TADAO, YAMAMOTO, KENJI
Applicants: SHINAGAWA REFRACTORIES CO, SHINAGAWA REFRACTORIES CO., LTD.
Application year: 1989
Main classification: B22D41
IPC codes: B22D41