US3828974A

US3828974A - Process for the emergency interruption of the flow of melt in a gravity casting plant

Info

Publication number: US3828974A
Application number: US00322627A
Authority: US
Inventors: O Tenner
Original assignee: GRAVICAST PATENT GmbH
Current assignee: GRAVICAST PATENT GmbH
Priority date: 1972-01-13
Filing date: 1973-01-11
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: JPS4880429A; GB1421832A; DE2300621C3; DE2300621A1; CH551242A; FR2167849A1; BE793868A; AT319504B; DE2300621B2; FR2167849B1

Abstract

In a gravity casting plant the melt is dammed up in a supply chamber up to a level which is higher than the level of the mouth of a casting nozzle. The melt flows from the supply chamber into an oblong equalization chamber and from this into the casting nozzle, and the flow of melt when operating the casting plant under normal conditions is controlled by a valve situated between the supply chamber and the equalization chamber. To avoid undesired outflow of melt from the casting nozzle at least the melt in the region of the mouth of the casting nozzle is cooled until same melt is solidified. A cooling member having an internal cooling system is provided on the nozzle to provide for the necessary cooling thereof.

Description

United States Patent Tenner [4 Aug. 13, 1974 1 PROCESS FOR THE EMERGENCY 3,121,769 2/1964 Horn 266/42 INTERRUPTION 0 THE F Q MELT 3,682,452 8/1972 Berczynski.... 266/42 X 3,705,61 12 1972 Tcnner 164 155 IN A GRAVITY CASTING PLANT 3,709,477 l/l973 Baumer et a1. 266/42 [75] Inventor: Oskar Tenner, Rossatz nr.

Niederosterr, Austria [73] Assignee: Gravicast Patentverwertungsgesellschaft m.b.H.

[22] Filed: Jan. 11, 1973 [21] Appl. No.: 322,627

[30] Foreign Application Priority Data Jan. 13, 1972 Austria 286/71 [52] US. Cl 222/1, 222/146 C, 266/42 [51] Int. Cl B22d 37/00 [58] Field of Search 222/146 C, 1, DIG. l5, 222/DIG. 4, DIG. 5, DIG. 20, 559; 164/155, 337; 266/38, 42

[56] References Cited UNITED STATES PATENTS 673,556 5/1901 Hartman 266/42 2,957,936 10/1960 Bugge 266/42 X Primary ExaminerRobert B. Reeves Assistant Examiner-David A. Scherbel Attorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 5 7 ABSTRACT In a gravity casting plant the melt is dammed up in a supply chamber up to a level which is higher than the level of the mouth of a casting nozzle. The melt flows from the supply chamber into an oblong equalization chamber and from this into the casting nozzle, and the flow of melt when operating the casting plant under normal conditions is controlled by a valve situated between the supply chamber and the equalization chamber. To avoid undesired outflow of melt from the casting nozzle at least the melt in the region of the mouth of the casting nozzle is cooled until same melt is solidifled. A cooling member having an internal cooling system is provided on the nozzle to provide for the necessary cooling thereof.

5 Claims, 2 Drawing Figures PROCESS FOR THE EMERGENCY INTERRUPTION OF THE FLOW F MELT IN A GRAVITY CASTING PLANT SPECIFICATION This invention relates to a process and a device for the emergency interruption of the flow of melt in a gravity casting plant.

It is a well known method in casting apparatus to dam up the melt in a supply chamber and to let it flow by the influence of gravity, preferably through an oblong equalization chamber, into a casting nozzle adjoining the casting mould. The melt in the supply chamber is kept at a level which is higher than the level of the mouth of the casting nozzle and a valve or closure is provided between the supply chamber and the casting nozzle to control or interrupt the flow of melt, respectively. In such machines the melt flows to the casting nozzle due to the influence of the weight of the melt dammed up in the supply chamber, and the flow pattern of the melt is tranquilized in the equalization chamber after having passed the closure, so that the turbulences introduced into the melt due to the influence of the valve or closure are tranquilized or removed so that the melt enters the casting nozzle free of turbulences. Within these machines, however, problems occur owing to the fact that in general the life of the valve or closure, which usually consists of a stopper and nozzle, is relatively short. This is due to the fact that the valve or closure or the devices used to operate it, e.g. a stopper rod, partly dip into the melt and partly protrude from the melt surface, which leads to an extremely high abrasion and premature destruction or wear of these areas of the valve or closure or operating devices which are only temporarily covered by the melt. This is on the one hand due to alternating temperature stresses and on the other hand to the chemical reaction between the atmosphere (oxygen) and the materials of the melt, the slag, the valve or closure as well as perhaps the refractory lining of the supply chamber and the equalization chamber. It is, therefore, inevitable to replace the closure or valve from time to time. When exchanging a stopper or a similar member within the known embodiment, it is necessary to lower the melt level in the supply chamber to below the level of the mouth of the casting nozzle to prevent that upon opening of the valve or closure for the exchange operation the melt is driven out of the casting nozzle as a result of the pressure of the melt volume dammed up in the supply chamber. After completion of the exchange operation the melt has to be refilled into the supply chamber up to the working level. This, however, leads to reactions between the materials of the melt, the slag, the refractory materials and the closure or valve elements respectively (stopper and nozzle) and the air and consequently to an unnecessary premature wear of the lining and of the valve or closure, which in turn results in considerably increased costs and idle times. Even if such reactions could be prevented, considerable time is necessary to drain and refill the melt, during which operation the machine is idle. This method of changing the stopper or any other valve or closure device, therefore, is accompanied by long idle times and production losses as well as high material wastes.

In such machines further problems may arise if a sudden destruction of the stopper or of the nozzle cooperating therewith arises or if a leakage occurs in the partition wall between supply chamber and equalization chamber or if a leakage in the support of the casting nozzle occurs. In such a case the melt flows out of the nozzle or around the nozzle like a fountain, which constitutes a danger for the working personnel. Besides, the outflowing melt may damage or destroy the plant. Especially when an automatic mould conveying system is used, such a melt outflow may produce considerable damage requiring long repair times and thus entailing high production losses.

It is an object of the invention to provide for a method by means of which the casting plant can be brought to a standstill for the exchange of the valve or closure or if a leakage occurs at the areas described above without requiring the draining of the melt.in the supply chamber below the level of the mouth of the casting nozzle.

It is a further object of the invention to make a casting plant of the kind described above more reliable in operation so that the danger for the working personnel is reduced.

It is another object of the invention to provide for a process for the emergency interruption of the flow of melt in a gravity casting plant, in which a reliable and quick shut-off of the flow of melt is achieved even if the control means for normally controlling the flow of melt out of the supply or storage chamber into the casting nozzle is damaged or out of order.

The'process according to the invention essentially consists in cooling at least the melt in the region or zone of the mouth or outlet opening of the casting nozzle until the melt in this zone or region is solidified whereby the flow of melt through the casting nozzle is interrupted independently from the control means used for normally controlling the flow of melt from the supply or storage chamber into the casting nozzle or an equalization chamber, to which the casting nozzle is connected. Thus the problems indicated above are solved by solidifying the melt in or at the casting nozzle by cooling the outflowing melt and thus preventing an undesired leakage of the melt at the casting nozzle independently from the control of the melt flow through the closure or valve serving for normally controlling the stream of melt out of the supply or storage chamber. Such a solidification of the melt flow in the range or zone of the casting nozzle can be done quickly and inexpensively thus permitting a repair or replacement of the valve or closure without requiring any draining of the melt in the supply or storage chamber. The invention can also be used with advantage in the case of a dangerous leakage of the support of the casting nozzle or of the separation or partition wall between supply chamber and equalization chamber, since it is easily possible to produce automatically a cooling of the melt at or around the casting nozzle, whenever extremely high temperatures occur in the vicinity of the casting nozzle. It is, eg very easy to determine immediately an undesired outflow of the melt at the casting nozzle or around it by means of temperature control means or temperature sensitive means of any suitable type known to one skilled in the art, or to register an inadmissable decrease of the level of the melt in the supply or storage chamber by means of a level gauge or level sensing means of any suitable well known type. These control or sensing means may be used to energize an automatic mechanism which initiates the cooling operation needed for the solidification of the melt in or at the casting nozzle. Thus, the safety of the plant is considerably increased, since in the case of a sudden breakdown of the stopper or of a similar closure or valve member an uncontrolled outflow of the melt from the casting nozzle is no longer possible so that there can no longer be any damage to the plant or any danger to the personnel. This results in a considerable increase of the production rate.

The cooling of the melt in the range of the casting nozzle could be achieved by spraying a cooling agent, e.g. water on to the nozzle. Since this, however, entails the danger of a formation of water vapour and oxyhydrogen gas, it is more advantageous to put a cooling closure member on to the casting nozzle, whenever this is to be cooled. Thus, any formation of oxyhydrogen gas and water vapour is prevented and there can be no explosions within the plant area. In accordance with a preferred method according to the invention the outer side of the support of the casting nozzle is also cooled, which has the advantage that leakages in the range of the support of the casting nozzle are sealed by the solidification of the melt in this area.

The inventive apparatus to carry out the method according to the invention is based on a casting machine which comprises a supply or storage chamber, a casting nozzle having an outlet opening and a control means for controlling the flow of melt due to the influence of the gravity from the supply chamber to the casting nozzle. Based upon this embodiment, the inventive device comprises a cooling device effective at least on the region or zone of the casting nozzle. This cooling device may be formed according to the invention by a cooling closure member for the casting nozzle, which can be removed, preferably lifted off, from the casting nozzle. A closure member may be a cooled cover or lid, a cooled stopper, a cooled plate, etc. However, it is also possible to use uncooled elements, if, owing to their own heat capacity, they produce the necessary temperature reduction of the melt to achieve a solidification of the melt. Preferably, according to the invention the cooling cover of the casting nozzle covers the casting nozzle and the surrounding area of the casting support member, in order to include this area, too, in the cooling range.

In accordance with a further development of the invention the cooling mechanism has a cooling system closed at least in the zone or region of the casting device with respect to the atmosphere, through which cooling system a stream of a cooling agent, e.g. water is conducted. Within such a closed cooling system the cooling agent is not in contact with the atmosphere but is conducted e.g. by a closed piping system. Therefore, the cooling agent cannot react with the atmosphere. There is no problem to design a closed cooling system in such a way that enough heat is conducted away to prevent the formation of any oxyhydrogen gas. Besides, suitable thermo-elements can be provided which prevent a superheating of the cooling fluid or control the amount of the cooling fluid.

The cooling mechanism or device which acts upon the area of the casting nozzle becomes effective whenever the stopper or any other valve member needs to be exchanged or when there is an undesired outflow of the melt from the casting nozzle or from the adjoining areas of the nozzle support. Since the invention also works whenever the stopper member or any other valve member or closure member breaks down, this member can be used until such a breakdown occurs, which allows for longer intervals between two succeeding exchanges of the stopper member or the like, compared with traditional apparatus.

If the machine or plant is to be put into operation again, e.g. after an exchange or repair of the damaged stopper member or after the repair of leakages, the solidified melt is again liquified in the zone or region of the casting nozzle. This can be done by various methods. First, the cooling, which had led to a solidification of the melt in the area of the casting nozzle, is removed or stopped. Then it is possible to knock out, for instance by means of hammer and chisel, a solidified plug in the casting nozzle, if it is not too strong. Another possibility consists in melting such a plug from above by means of an oxygen lance, or another heating device, e.g. electric heating wires for the casting nozzle or its surrounding region. Finally, it is also possible to liquify the solidified melt by means of the effect of the heat of the following melt present in the equalization chamber or supply chamber alone, particularly if heat losses are prevented in the zone of the casting nozzle, e.g. by means of a heat insulating cover consisting of asbestos or wool of kaolin, so that there is an accumulation of heat in or at the casting nozzle.

A schematic illustration of the apparatus or device according to the invention is shown in the accompanying drawing. FIG. it shows a vertical section through the apparatus, whereas FIG. 2 represents a section according to line II II.

The supply chamber 2 formed by a supply or storage container 1 is filled with melt 3, e.g., metal or a synthetic resin or plastic material. The level 4 of the melt 3 in the supply or storage chamber 2 is essentially kept constant by a device (not shown) suitable for this purpose. Such devices are well known to one skilled in the art. A stopper rod 5 plunges into the melt 3 and has at its bottom end a stopper 6 which constitutes the closure member for an opening 7 of a nozzle member 8, which is inserted into the bottom wall of the supply chamber 2. The opening 7 connects the supply chamber 2 with an oblong hollow cylindrical equalization chamber 9, in which the flow pattern of the melt is tranquilized.

At its upper end the stopper rod 5 is fixed to a stopper support 10. The stopper support 10 shows a cylindrical protrusion 11, which fits into a bore 12 of the stopper rod 5 and is fixed thereto by means of a screw 13 which intersects the stopper rod 5 and the protrusion 11. The stopper support 10 is vertically adjustable and is guided for upward and downward movement by means of rollers 14. This movement is effected by means of a lever 15, which is pivotally mounted on a fixed swivel point 16.

The member confining the equalization chamber 9, which member is constituted, e.g., by an oblong pipe 17, is connected to a casting nozzle 18. In order to heat the melt in the equalization chamber 9, any wellknown suitable heating device (not shown) can be used, e.g., an induction heating device which is connected with the equalization chamber 9 by means of openings 19 in the wall of the pipe 17. The casting nozzle 18 has ducts 20 through which a cooling fluid, e.g., water, can pass and/or through which electric resistance heating wires (not shown) run. Thus a cooling or heating of the casting nozzle can be achieved, so that the melt in it can be solidified or reliquified, as it is desired.

A console 21 is fixed to the wall of the supply chamber 1. To this console 21 swivelling arm 23 is linked by means of a bolt 22 so that this arm 23 can be pivoted in a horizontal plane. A swivelling arm 25 with a cooling member 26 at its end is fixed to arm 23 by means of a pivot means 24, so that this arm 25 can be pivoted in a vertical plane. In its lowermost position shown in FIG. 1 by full lines, this cooling member 26 is situated exactly above the casting nozzle 18. The cooling member 26 has a protrusion 27, which entersinto the casting duct 28 of the casting nozzle 18 and on the one hand serves for centering the cooling member 26 from the casting nozzle 18 and on the other hand serves to enhance the cooling effect on the casting nozzle 18. Due to its own heat capacity the cooling member 26 may have a cooling effect on the melt in the casting duct 28 of the casting nozzle 18 or may contain a builtin cooling system (not shown) to further intensify the cooling effect. The cooling fluid, e.g., water, of this cooling system is supplied or sucked off, respectively, via the pipes 29.

In order to achieve the vertical swivelling motion of the cooling member 26 a unit 30 formed by a hydraulic or pneumatic piston and a cylinder is provided, which unit is journally mounted to a pivot 31 forked at one end, which pivot is rigidly connected to the bolt 22. The piston rod 32a ofthis unit 30 is pivotally connected by a joint to arm 25. Thus the arm 25 and the cooling member 26 can be lifted to the position 25', 26' shown with dashed lines in FIG. 1, in which position the cooling member 26 releases the casting nozzle 18 so that the casting nozzle is free for its usual purposes, e.g., filling a mould (not shown) with melt.

The arm 25 with the cooling member 26 can also be horizontally swivelled in the direction of the double arrow 37 (FIG. 2), so that operations near the casting nozzle 18, e.g., replacing of moulds or similar, are not hampered. To achieve this horizontal motion a bevel gear pinion 32 is connected to the pivot 31 and cooperates with a further bevel gear pinion 33 which can be turned in any desired direction by a motor 34. Such a sideswivelled position of the cooling member 26 is shown in FIG. 2 with dashed and dotted lines.

If there is adamage or a leakage at the stopper 6, at

I the nozzle 8, at the wall 35 separating the supply chamber 2 from the equalization chamber 9, at the casting nozzle 18 or at the support 36, the cooling member 26 is brought into the position shown will full lines in FIG. I by swivelling the

arms

23, 25. In this position the cooling member 26 closes the casting nozzle 18 and by its cooling effect produces a solidification of the melt in the casting duct 28 of the casting nozzle 18. Since the cooling member 26 has a plate 26" carrying the protrusion 27, it extends also over the support of the casting nozzle 36, so that, if a suitable size of the cooling member 26 or its cooling system is provided for, the cooling effect can be extended to the zone or area in the vicinity of the casting nozzle 18, particularly to the support of the casting nozzle 36, so that the melt, which might flow out of leakage gaps in this zone or area, is also solidified. Now the stopper rod 5 can be exchanged without any further difficulties, which exchange is facilitated through the rcmovable connection between the stopper rod 5 and the stopper support 10. In the case of a leakage, however, the melt in the supply chamber 2 can be drained off directly or indirectly through the equalization chamber 9, after solidification of the melt in the casting nozzle 18 without any risk of damage to the plant or the personnel. After the melt has been drained off, the necessary repair work can be carried out.

If the machine is to be put into operation again, the cooling member 26 is brought into the position 25' shown with dotted lines in FIG. 1, and is swivelled to the side, if necessary, by swivelling the

arms

23 or 25, respectively. The cooling of the casting nozzle 18, which is effected by the cooling fluid flowing through the channel 20 is interrupted, so that there is no longer any cooling effect on the casting nozzle 18 at all. The solidified melt in the casting nozzle 18 is reliquified by heating. For this purpose, it is useful to cover the casting nozzle 18 as well as the surrounding region of the casting nozzle support 36 with heat insulating material, e.g., asbestos. If necessary, the electric heating wires in the channel 20 can be energized or the solidified melt plug in the duct 28 can be liquified from above by means of an oxygen flame, or the plug of the solidified melt can be mechanically removed.

Of course it is also possible to use cool air as a cooling agent, e.g., which is conducted through the conduits 20 of the casting nozzle 18. Extreme freezing agents, particularly inert gases, e. g., liquid nitrogen, helium or CO can also be used. In all cases in which liquid or gasous cooling agents are used, it is advisable to employ this cooling agent in a closed system, e.g. pipes or tubes, to prevent the formation of inflammable gases. This closed cooling system can be formed by the channels 20 leading to the casting nozzle 18 and/or by the system in the cooling member 26 connected to the conduits 29, which may be formed by hoses.

Of course the invention can also be used in casting plants in which the equalization chamber 17 is partly or entirely situated within the supply chamber 1 and is at least partly surrounded by the melt contained in the supply chamber.

I claim:

1. A process for the emergency interruption of the flow of melt in a gravity-type casting plant having a supply chamber,

an upwardly directed casting nozzle spaced from said supply chamber and having an outlet opening, control means for controlling the flow of melt under its own weight from the supply chamber to the cast ing nozzle and damming up the melt in the supply chamber to a higher level than the level of the outlet opening of the casting nozzle, comprising the steps of temporarily closing the casting nozzle from above,

and then forming a plug in the casting nozzle by cooling the melt at least in the region of said casting nozzle until said melt is solidified in said region and thereby interrupts the flow of melt through the casting nozzle independently of said control means and avoids undesired overflow of the melt.

2. The process of claim 1, wherein the step of damming up the melt in the supply chamber by cooling the region of the casting nozzle comprises the placing of a cooling member on the casting nozzle and holding the cooling member on the casting nozzle until at least the melt in the region of the mouth of said casting nozzle is solidified and forms a plug.

3. The process of claim 1, wherein upwardly directed passageway means form a support for said casting nozzle and wherein the step of cooling the melt in the re- 3,828,974 7 8 gion of the casting nozzle includes the step of cooling tween the control means and casting nozzle. the Casting nozzle Support around the passageway 5. The process of claim 1, including the step of reesmeans.

4. The process of claim 1 including the p of q tabllshlng the flow through said cooling nozzle by meltizing the level between said control means and said ing the P thereincasting nozzle by flowing the melt in the region be-

Claims

1. A process for the emergency interruption of the flow of melt in a gravity-type casting plant having a supply chamber, an upwardly directed casting nozzle spaced from said supply chamber and having an outlet opening, control means for controlling the flow of melt under its own weight from the supply chamber to the casting nozzle and damming up the melt in the supply chamber to a higher level than the level of the outlet opening of the casting nozzle, comprising the steps of temporarily closing the casting nozzle from above, and then forming a plug in the casting nozzle by cooling the melt at least in the region of said casting nozzle until said melt is solidified in said region and thereby interrupts the flow of melt through the casting nozzle independently of said control means and avoids undesired overflow of the melt.

3. The process of claim 1, wherein upwardly directed passageway means form a support for said casting nozzle and wherein the step of cooling the melt in the region of the casting nozzle includes the step of cooling the casting nozzle support around the passageway means.

4. The process of claim 1, including the step of equalizing the level between said control means and said casting nozzle by flowing the melt in the region between the control means and casting nozzle.

5. The process of claim 1, including the step of reestablishing the flow through said cooling nozzle by melting the plug therein.