US3736980A

US3736980A - Mold for continuous centrifugal casting

Info

Publication number: US3736980A
Application number: US00212997A
Authority: US
Inventors: P Peytavin; L Babel
Original assignee: ETUDES DE CENTRIFUGATION
Current assignee: ETUDES DE CENTRIFUGATION
Priority date: 1970-12-30
Filing date: 1971-12-28
Publication date: 1973-06-05
Anticipated expiration: 1990-06-05
Also published as: FR2119874A1; BR7108649D0; NL167619B; NL167619C; GB1366336A; AT320185B; FR2119874B1; DE2165382C3; IT944458B; DE2165382A1; ES398452A1; JPS5334165B1; CH550038A; BE777468A; DE2165382B2; NL7118061A

Abstract

Mold for continuous centrifugal casting comprises a rotary inner part in contact with the metal being cast and a stationary outer part through which cooling liquid is supplied, the two parts being connected by rotary seals of the labyrinth type.

Description

ited States Peytavin et a1.

June 5, 1973 MOLD FOR CONTINUOUS CENTRIFUGAL CASTING Inventors: Pierre Peytavin, Neuilly-sur-Seine; Louis Babel, Sauvigny-les- Bois, both of France Assignee: Societe Civile DEtudes DeCentrifugation, Paris, France Filed: Dec. 28, 1971 Appl. No.: 212,997

Foreign Application Priority Data Dec. 30, 1970 France .7047337 US. Cl. ..164/283, 164/84, 164/297 Int. Cl. ..B22d 11/06, B22d 13/02 Field of Search ..164/84, 89, 273,

[56] References Cited UNITED STATES PATENTS 3,022,552 2/1962 Tessman ..164/283 X 3,487,876 1/1970 Bucci ..l64/84 X 3,651,859 3/1972 Wahl et a1. ..164/297 X FOREIGN PATENTS OR APPLICATIONS 721,696 l/l955 Great Britain 164/297 Primary ExaminerJ. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Joseph F. Bris'ebois and John A. Feketis [57] ABSTRACT Mold for continuous centrifugal casting comprises a rotary inner part in contact with the metal being cast and a stationary outer part through which cooling liquid is supplied, the two parts being connected by rotary seals of the labyrinth type.

19 Claims, 2 Drawing Figures Patented June 5, 1973 3,736,980

2 Sheets-g 1 Patentgcl June 5, 1973 3,736,980

eeeeeeeeeeee t2 MOLD FOR CONTINUOUS CENTRIFUGAL CASTING SUMMARY OF THE INVENTION This invention relates to a mold for use in the continuous rotary vertical casting of steel castings.

The molds used in known processes of continuous casting are generally cooled by circulating water therethrough and comprise, for this purpose, a hollow annular or tubular space, the internal wall of which is the cooling wall of the mold proper.

In order to permit this circulation of water the rotary molds in present use comprise rotary seals which ensure fluid tightness between the mobile rotary part of the seal and the fixed support for the mold through which the cooling water is supplied and withdrawn.

In view of the relatively large flow of water required to cool the mold, these seals must be constructed to ensure adequate sealing at relatively high pressures and are thus subject to considerable wear during rotation of the mold.

It follows that it is not possible to turn the molds at high speeds in actual practice because the sealing means are not capable of tolerating such rotary speeds. However, the lower speeds used are nevertheless sufficient to cause relatively rapid deterioration of the seals, which must then be replaced.

The invention therefore proposes that a rotary mold be provided which is cooled by the circulation of a fluid, normally water, and which is capable of turning at very high speeds while engendering relatively little friction. Moreover, the mold according to the invention does not require frequent changing of the seals and is thus much more economical to operate than the molds heretofore known.

It is an object of the present invention to provide a mold for continuous vertical rotary casting which is cooled externally by the circulation of a cooling fluid and comprises a rotary part constituting the mold proper and having a cooling wall, together with a stationary coaxial part for supplying fluid and directing this fluid against the cooling wall, characterized by the fact that the rotating and stationary parts define at least one annular labyrinth to force said fluid, or at least the greater part thereof, to flow along the cooling wall.

As a consequence of the invention it is possible to have only very small leakage at the level of the stationary member through which the fluid is supplied, even though the device comprises one or more distribution chambers having a substantial volume and the fluid is under high pressure in order to ensure a regular flow the full length of the cooling wall.

In a preferred embodiment of the invention the stationary part through which the fluid is supplied is concentric with the rotating part and is positioned, for example, around the upper part thereof. In this case, the labyrinth is preferably formed, on the one hand, by the upper substantially horizontal surface of the stationary part for supplying fluid and by the upper flange of the rotating part which is positioned facing this upper surface. Thus, the fluid, water for example, directed against the cooling wall of the rotating part of the mold, cannot escape through this upper labyrinth, except for minor leakage, and is thus led to descend the length of the cooling wall of the rotating part of the mold until the bottom of this wall, from whence it is exhausted. In such an embodiment, it may be advantageous, in order to obtain a particularly compact and well-guided mold, to position the bearings directly supporting the mold around the rotating part of the mold, and thus directly above or below the stationary member for supplying water to the mold. In this case, in accordance with the invention, the rotating part of the mold comprises, on the one hand, a concentric portion positioned, with a certain clearance, around the cooling wall of the mold, so as to define with this wall an annular canal and, on the other hand, a flange fixed to said rotating portion and extending between the stationary supply means and the stationary part of the bearings, or journals, said flange defining, with the opposite surface of the stationary supply part, a labyrinth to prevent the passage of water, except for minor leakage.

In such an embodiment, the device for supplying liquid may, for example, consist of a stationary ring defining a single chamber for holding fluid under pressure and having one or more openings in its inner part in the vicinity of the external cooling wall of the mold. The upper and lower walls of this ring form, with the corresponding flanges of the rotating part, labyrinths preventing the escape of the water from either side of the ring. The outer part of the ring has one or more radial supply ducts positioned, for example, in the vanes connecting said ring to a concentric outer support, and the spaces between said vanes permit the passage and descent of cooling water from leakages through the upper labyrinth.

The discharge of the fluid or the cooling water may be into the open air, or through a duct, for example, a toroid in form, similar to the stationary supply means, in which case one or more sealing labyrinths may also be provided at the level of discharge.

When the rotating part of the mold has an external portion which is concentric with the cooling wall and defines therewith an annular duct, it is possible to position at the bottom of this portion one or more radial outlets opening, on the one hand, into the open air and, on the other hand, into the lower part of said annular cooling duct.

' When, in accordance with a variation of the invention, the support for the mold is not positioned directly around the part in contact with the liquid metal of the mold, it is possible to eliminate the concentric portion, with the annular cooling duct being then defined, on the one hand, by the external wall of the rotating part of the mold and, on the other hand, by a stationary wall of the means for supplying cooling fluid opposite said external wall. In accordance with a preferred embodiment of the invention, the teeth of the sealing laby rinths are vertically positioned. The play between the teeth may be, for example, of the order of 0.5 mm in a vertical direction and 1.5 mm in a radial direction, allowing for the fact that the greatest expansion due to the heat caused by the casting takes place radially. Experience has shown that, with such clearances, for the rate of flow utilized, the total leakage of water may be limited to about 15 percent.

The invention is particularly adapted to the rotary casting of solid cylindrical castings in which the speed of rotation of the mold is generally between 30 and r.p.m.

Other advantages and characteristics of the invention will appear from a reading of the following description of a preferred embodiment of the invention, given purely by way of illustration, with reference to the accompanying drawings, in which:

FIG. I is an axial sectional view according to the invention; and

FIG. 2 is a schematic perspective view of the stationary supply portion of said mold.

The mold illustrated and described below is adapted for use in a process of continuous rotary vertical casting but, of course, the invention is equally applicable to a continuous rotary casting process utilizing a nonvertical axis.

The mold illustrated comprises a movable part I rotating about a vertical axis 2. The mold per se consists of a cylindrical or slightly frusto-conical portion 3 made of copper or like metal, the internal wall 4 of which is directly in contact with liquid metal while the steel is being continuously being poured.

This portion 3 has an external surface 5 forming the cooling surface in direct contact with the circulation of cooling water. At its upper end the rotary copper member 3 is attached to a horizontal flange 6 which is surmounted by an annular removable protective member 7 adapted to protect the upper surface of the flange 6 from contact with splatters of liquid or incandescent taken through a mold particles. Beneath the inner surface of this horizontal flanges 6 is the stationary water-supplying part of the mold consisting principally of a toroid 8 which is rectangular in section, and the hollow interior of which encircles the upper part of the external cooling wall 5. This toroid defines a single annular chamber holding a substantial volume of water under pressure in order to ensure a regular flow of water along the length of the wall 5. As may be seen in greater detail on FIG. 2, the toroid 8 is attached by vanes It) to a cylindrical member 11, which is itself attached by a flange to a support 12. The cooling water is introduced into the toroid 8 through an outer duct, not shown, opening into an oritice 13 in the member 1B. This orifice leads to a duct inside the vane in alignment with the orifice 13, said vane 10 having, for example, a width greater than that of the other vanes M in order to accommodate the duct leading the water to the interior of the toroid 8. Of course, it is also possible to bring the water into the totold through several vanes such as lltl.

In accordance with the invention, the upper surface of the toroid 8 is provided with a certain number of circular teeth which form a sealing labyrinth 14 with the corresponding teeth on the lower surface of the rotating flange 6, in order to require almost all the cooling water to run the length of the cooling wall 5 toward the bottom. Taking into account, however, the high pressure of the liquid in the toroid 8, a small part of the cooling water leaks along the labyrinth I4 and, circulating between the flange 6 and the upper part of the toroid 8, reaches the periphery of the toroid. At this point, the leakage water descends between the vanes 10 to be discharged in the direction of the arrows shown in the drawing.

As seen on FIG. I, the toroid 8 may advantageously comprise a radioactive source 115 in the form of a tube passing through a protective cylinder 16, of lead for example, or of any other suitable material, said cylinder having, on the side of the axis 2, a radial section of material 17 which is permeable to radiation in order to permit the source to supply radiation toward the axis of rotation 2 of the mold.

A radiation-sensitive device, not shown, diametrically opposite the source 15, and preferably outside the mold, receives the radiation of the source, and is adapted to controlthe level of the rnetal'inside the mold 3.

In accordance with a particularly valuable embodiment of the invention, the rotating part 1 of the mold is supported by stationary bearing means carried by arms 19 similar to the vanes 10, on the support 12, said bearing means 18 being positioned concentrically of the mold 1 below the supply toroid 8. In this case, as in the embodiment previously described, the external cooling wall 5 extends almost the full height of the mold 3, and is attached to a concentric portion 19 which extends, for reasons of strength, to the upper part of the mold. Orifices 20 are then provided in this portion 19 opposite the chamber 9 in the toroid 8 to permit the passage of water to the cooling wall 5. This portion 19 is spaced from wall 5 to form an annular duct 2H extending almost the full height of the mold so that the portion 19 is itself at a very low temperature which is no greater than the temperature of the cooling water. The portion 19 has an internal bearing race 22 opposite a race 23 carried by the support 18.

In order to prevent the cooling water from reaching the bearings 25, the portion 19 has, according to one embodiment of the invention, an intermediate flange 26, extending between the toroid 8 and the support 18. In accordance with the invention, this flange 26 has a certain number of circular teeth cooperating with circular teeth on the lower surface of the lower wall 27 of the toroid 8 to form a sealing labyrinth 28. The leakages which occur pass outwardly along the upper sur face of the flange 26 and fall along an inclined edge of the flange 26 between the arms 19 to rejoin the water from the leakages of the labyrinth 14.

in a preferred embodiment of the invention the labyrinths such as 14 and 28 have a vertical clearance between their teeth which is less than the radial clearance between these teeth, since the expansion of the rotary part of the mold is greater than the vertical expansion of the mold. For a mold according to the invention having an interior wall 3 made of copper and a diameter of the order of to mm, the vertical clearance between the tops of the teeth and the bottoms of the grooves therebetween is of the order of 0.5 mm, whereas the radial clearance between the opposed sides of the teeth is of the order of 1.5 mm.

In the mold illustrated in the drawings the cooling water is removed through the lower part of the mold. For this purpose the lower part of the portion 19 has a substantially horizontal flange 29 provided with a certain number of radial passages 30 opening into the lower part of the annular duct 21. These passages 30 then open into an annular inclined duct 31 formed by the deflectors 32 and 33 positioned at the end of the horizontal flange 29. From this point the cooling water passes out through a vertical annular discharge duct 34 positioned between the arms 19, the discharged water being then rejoined by the leakage water from the labyrinths M and 28.

The mold according to the invention may be mounted to rotate freely, in. which case it is driven in rotation by the solid part of the casting being poured, which is itself driven in rotation in a known manner by the extractors, or the mold itself may be directly driven. In this case it comprises, for example, a toothed ring 35 engaging a gear wheel 36 on driving means shown in phantom lines on the drawings. in this case, a tubular inclined passage is provided in place of the arm 19 at this position in order to permit access by the pinion 36 to this tubular member, while protecting it from the leakage and discharge water.

The bearings 25 and/or the ring 35 may advantageously be lubricated by a film of oil, which film is introduced through one or more radial orifices, not shown, passing through the support 18. A labyrinth member 36 may be provided between the lower part of the deflector 33 which rotates and the lower part of the support 18 in order to prevent the escape of lubricating oil in the outlet water.

The invention as shown on the drawing is, of course, subject to modification in many ways. Thus the stationary means for supplying water such as the toroid 8 may be positioned midway of the height of the mold or at its bottom instead of at the top of the mold, in which case a water outlet may also be provided at the upper part of the mold. It is also possible to position the water supply means coaxially above or below the rotary mold, with the water then leaving the device not in a radial direction but in a more or less axial direction. The teeth of the labyrinth may, in this case, be horizontal, instead of being vertical as in the drawing. On the other hand, the rotary part of the mold may be supported by means positioned above or below the part 3 in contact with the metal, and which may be cooled. In this case the intermediate flanges such as 26 may be unnecessary and it is also possible to eliminate the portion 19 which may then be replaced by a wall concentric with the wall 5 and attached to the supply means such as 8. However, it will be seen that the invention makes it possible, as in the case of the embodiment described, to provide in a compact manner, concentrically with cooling wall 5, both a support for the mold, a driving ring, and a fixed supply means, all while guaranteeing the water tightness of the bearings and teeth, and permitting the radioactive source for controlling the molten metal level to be judiciously positioned.

While one particular embodiment of the invention has been described, it is obvious that the scope of the invention is not limited to the details thereof and that it may be modified as to detail without thereby departing from the basic principles of the invention'as defined by the following claims:

What is claimed is:

1. In a mold for the continuous vertical rotary casting of metal, which mold is externally cooled by the circulation of a cooling fluid, said mold comprising a cylindrical rotary member mounted on bearings and constituting the mold proper, said rotary member having an external cooling surface, and stationary coaxial supply member for bringing liquid into contact with the cooling wall, the improvement comprising an annular labyrinth defined by interfitting teeth carried by said rotary and stationary parts, which prevent the escape of the greater part of said cooling fluid until it has travelled substantially the full length of the cooling wall.

2. Mold as claimed in claim 1 in which the stationary supply member is positioned concentrically about said cooling surface and defines at least one fluid distributing chamber.

3. Mold as claimed in claim 1 in which the rotary member comprises a portion extending coaxially of said outer supply member and at a certain distance therefrom to define therebetween an annular cooling duct.

4. Mold as claimed in claim 3 which comprises at least one bearing positioned concentrically of said coaxial portion, said bearing being spaced from the fixed supply member by an intermediate flange carried by said rotating member and forming, with an opposite surface on said fixed supply member, a sealing labyrinth.

5. Mold as claimed in claim 2 in which a surface of the stationary supply member opposite the surface forming a labyrinth carries a second flange fixed to the rotating part, with which itforms a second sealing labyrinth.

6. Mold as claimed in claim 5 characterized by the fact that the stationary supply member is positioned above said bearing, with said intermediate separating flange extending between these two members about half way of the height of the mold.

7. Mold as claimed in claim 3 in which said coaxial portion extends for the full height of the rotating part of the mold and has orifices near the outlet of the stationary supply member opening into said annular cooling duct.

8. Mold as claimed in claim 3 which comprises at its bottom a rotating flange having at least one radial duct leading, on the one had, to the lower part of the annular cooling duct and on the other hand, to stationary discharge means.

9. Mold as claimed in claim 8 in which said radial ducts lead to deflectors defining one or more annular ducts opening into said stationary discharge means.

10. Mold as claimed in claim I in which said fixed supply member for supplying cooling liquid is a hollow toroid.

l1. Mold as claimed in claim It) in which said toroid is substantially rectangular in section with one of its lower and upper surfaces provided with labyrinth teeth.

12. Mold as claimed in claim 11 in which the upper surface of the toroid has a sealing labyrinth and in which said toroid is connected to a stationary concentric support by a plurality of vanes defining therebetween passages permitting the descent of water coming from leaks from the upper labyrinth.

l3. Mold as claimed in claim 4 in which said intermediate flange terminates in a curved edge.

14. Mold as claimed in claim 10 which has at least one radioactive source inside said torus.

15. Mold as claimed in claim 1 which comprises a driving ring gear.

16. Mold as claimed in claim 15 in which the ring gear is attached to the exterior of one of the deflectors, the lower edge of said deflector forming at least one sealing labyrinth with a corresponding surface on the bearing of the mold.

l7. Mold as claimed in claim 1 in which, in the zone at which the liquid is discharged from the rotating member, said rotating part defines, with at least one of the surfaces of the discharge member, at least one sealing labyrinth.

l8. Mold as claimed in claim 1 comprising an annular protective element attached to its upper part.

19. Mold as claimed in claim 4 comprising means for supplying said bearing with a film of oil.

Claims

5. Mold as claimed in claim 2 in which a surface of the stationary supply member opposite the surface forming a labyrinth carries a second flange fixed to the rotating part, with which it forms a second sealing labyrinth.

10. Mold as claimed in claim 1 in which said fixed supply member for supplying cooling liquid is a hollow toroid.

11. Mold as claimed in claim 10 in which said toroid is substantially rectangular in section with one of its lower and upper surfaces provided with labyrinth teeth.

13. Mold as claimed in claim 4 in which said intermediate flange terminates in a curved edge.

15. Mold as claimed in claim 1 which comprises a driving ring gear.

17. Mold as claimed in claim 1 in which, in the zone at which the liquid is discharged from the rotating member, said rotating part defines, with at least one of the surfaces of the discharge member, at least one sealing labyrinth.

18. Mold as claimed in claim 1 comprising an annular protective element attached to its upper part.