US3752217A

US3752217A - Float-distributor for direct chill casting

Info

Publication number: US3752217A
Application number: US00171462A
Authority: US
Inventors: P Sevier
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1971-08-13
Filing date: 1971-08-13
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14

Abstract

A float-distributor for direct chill casting of metals, particularly, aluminum and aluminum base alloys. The floatdistributor comprises a float adapted to float on the surface of the molten metal in the mold. The float is adapted to fit about a feed nozzle which supplies the molten metal to the mold. Means for distributing the molten metal about the periphery of the mold is provided and is supported beneath the float. The distributing means generally comprises a cone shaped distributor which is supported in axial alignment with the feed nozzle. The apex angle of the distributor is generally kept between about 60* and 150*. The float may include means for increasing its buoyancy as the flow rate of molten metal issuing from the feed nozzle increases. The float may also contain means for preventing capillary flow of molten metal between the float and the feed nozzle.

Description

United States Patent 1191 Sevier 1 51 Aug. 14, 1973 FLOAT-DISTRIBUTOR FOR DIRECT CHILL [73] Assignee: Olin Corporation, New Haven,

Conn.

[22] Filed: Aug. 13, 1971 [21] Appl. No.: 171,462

[52] US. Cl. 164/281, 137/432 3,349,838 10/1967 Baier Primary Examiner-Robert D. Baldwin Attorney-Robert l-l. Bachman et a1.

[5 7] ABSTRACT A float-distributor for direct chill casting of metals, particularly, aluminum and aluminum base alloys. The float-distributor comprises a float adapted to float on the surface of the molten metal in the mold. The float is adapted to fit about a feed nozzle which supplies the molten metal to the mold. Means for distributing the molten metal about the periphery of the mold is provided and is supported beneath the float. The distributing means generally comprises a cone shaped distributor which is supported in axial alignment with the feed nozzle. The apex angle of the distributor is generally kept between about 60 and 150. The float may include means for increasing its buoyancy as the flow rate of molten metal issuing from the feed nozzle increases. The float may also contain means for preventing capillary flow of molten metal between the float and the feed nozzle.

32 Claims, 4 Drawing Figures Patented Aug. 14, 1973 3,752,217

5 Sheets-Sheet l INVENTOR: PETER E. SEWER ATTORNEY Patented Aug. 14, 1973 5 Sheets-Sheet 3 PETER E. SEWER INVENTOR ATTORNEY FLOAT-DISTRIBUTOR FOR DIRECT CHILL CASTING BACKGROUND OF THE INVENTION This invention relates to an improved floatdistributor for the direct chill casting of metals, particularly, aluminum or aluminum based alloys. Improved cast structure and surface appearance is obtained for direct chill cast ingots, particularly, extrusion ingots, together with increased casting speed, by the use of a float-distributor that has a conical distribution element and a low metacentric height. The float-distributor also acts simultaneously as a flow control valve.

In the direct chill casting process, the difficulty in obtaining a uniform distribution of molten metal about the periphery of a cylindrical extrusion ingot mold is well known. Uniform distribution is essential if inhomogeneities in ingot structure leading to poor metal finishing performance in the subsequent extrusion are to be avoided. It is important that the structure of the extrusion ingot be substantially free from transverse and longitudinal inhomogeneities.

Transverse inhomogeneities are most often caused by using a float-distributor which has a number of radially disposed discharge ports; the jet of hot metal leaving each port causes structural differences in the ingot yielding a flower petal pattern structure formed by a mixture of coarse and fine dentritic elements.

US. Pat. Nos. 3,289,291, granted June 23, 1969 and U.S. Pat. No. 3,050,792, granted Aug. 28, 1962 illustrate typical prior art designs which are subject to such transverse inhomogeneities.

Longitudinal inhomogeneities are caused by phenomena in the air gap between the mold wall and the ingot surface where it has shrunk away from the mold wall. This defect is commonly known as the Altenpohl band and can be minimized by keeping a small head of metal within the mold.

Direct chill casting with a small head of metal in the mold is generally more difficult than casting with a large head of metal. It demands accurate alignment of the central feed nozzle and its associated floatdistributor which controls both the level of metalin the mold and its distribution.

Float-distributors with a flat control surface as in that the apex angle of the cone must be limited within specific ranges in order to obtain the desired distribution of metal within the mold. The more acute the apex angle, the greater is the tendency of the molten metal to be driven down into the cast ingot and, thereby, form a deeper crater. The formation of a deep crater makes the ingot subject to cracking or hot tearing and is particularly deleterious when casting stress sensitive alu-. minum alloy because it increases the thermal stresses which occur in the cast ingot.

SUMMARY OF THE INVENTION In accordance with this invention, an improved cone shaped float-distributor has been developed which simultaneously produces a substantially uniform lateral distribution of molten metal to the casting, coupled with a fine degree of level control within the mold. The float-distributor of this invention also provides increased stability of operation at high casting speeds because it has a relatively low metacentric height.

The float-distributor of this invention comprises a novel float means which is adapted to maintain accurate alignment between a conical distributor element and a feed nozzle. The float further includes means for preventing molten metal from flowing by capillary action between the float and the feed nozzle and means for increasing the bouyancy of the float as molten metal flow rates increase in order to provide improved valving action by the distributor element and to shut off the flow of metal from the feed nozzle at high flow rates.

The distributor element of the float-distributor of this invention has a conical shape with the top portion of the cone being rounded off into a spherical surface to increase the tolerance of the distributor to vertical misalignment between the feed nozzle and the distributor. The cone shaped distributor is generally formed of a material having a density greater than or equal to that of aluminum and, preferably, a density at least twice as great as that of aluminum.

The support arms which connect the float to the distributor cone are kept as small as possible so that a substantially uniform distribution of metal is provided US. Pat. No. 3,050,792 are often used and the metal in the mold flows radially outward. The multiple discharge ports in the bottom of the float-distributor cause unequal metal distribution in the horizontal plane resulting in the flower petal defect discussed above.

Further, such distributors of the type shown in the patent tend to float with only a small part of their total volume submerged because they have a high metacentric height and as the casting speed of the ingot is increased, the distributor tends to discharge more metal from the ports of one side than from the remaining ports, and thus, tilts with respect to the feed nozzle. This tilting problem is self-propagating since there is no effective restoring couple and the tilt is usually only limited when the feed nozzle interferes with the hole in the distributor. This tilting probelm exaggerates the unequal distribution of metal through the discharge ports and, consequently, further deteriorates the microstructure of the resulting ingot.

Cone shaped distributors have been employed in U.S. Pat. No. 2,891,291 and French Pat. No. 1,385,585; however, it has not been recognized in these patents about the 360 periphery of the mold. Preferably, the distributor element and support arms are an integral one piece casting which is readily assembled to the float by means of Pal nuts or Tinnerman speed nuts.

Accordingly, it is a principal object of this invention to provide a float-distributor for direct chill casting of molten metals, particularly, aluminum or aluminum based alloys having improved uniformity of distribution of molten metal about the periphery of the mold.

It is another object of this invention to provide a float-distributor as above, wherein the distributor ele ment has a conical shape.

It is a further object of this invention to provide a float-distributor as above, wherein the float includes means for preventing flow of molten metal between the float and the feed nozzle by capillary action.

It is a still further object of this invention to provide a float-distributor as above, wherein the float includes means for increasing its bouyancy as molten metal flow BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is-a partial cross sectional view of a typical float-distributor assembly in accordance with this invention.

FIG. 2 is a perspective view of a typical conical distributor element in accordance with this invention.

FIG. 3 is a cross sectional view of a typical floatdistributor assembly in accordance with this invention in place in a direct chill casting apparatus prior to the beginning of casting.

FIG. 4 is a cross sectional view of a float-distributor assembly in accordance with this invention in place in a direct chill casting apparatus during casting.

I DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings an especially to FIG. 1, there is shown a partial cross section of a floatdistributor l in accordance with this invention. The float-distributor 1 comprises a float 2, a distributor ele' ment 3 and means 4 connected to the float 2 for supporting the distributor element 3.

The float 2 is of a highly novel design and is adapted to have a feed nozzle 5 protrude through it. The float 2 comprises a bottom portion 6 which contacts the molten metal in the direct chill casting mold, a top portion 7 and a peripheral wall 8. The peripheral wall 8 may have any desired shape but is preferably shaped to conform to the inside periphery of the mold and for most applications, therefore, it has a cylindrical shape.

The float 2 has a hole 9 passing substantially centrally through it extending from the top portion 7 to the bottom portion 6. The hole 9 comprises at least two portions. The first portion 10 has a diameter substantially greater than the feed nozzle 5 and provides means for preventing flow of molten metal between the float 2 and the feed nozzle 5 by capillary action.

The second portion 11 of the hole 9 has an inside diameter which is just slightly greater than the outside diameter of the feed nozzle 5. The second portion 11 of the hole 9 provides means for maintaining the centering of the distributor element 3 below the feed nozzle 5. Preferably, the inside diameter of the second portion 11 is from about 0.050 to 0.200 inch larger than the outside diameter of the feed nozzle 5, and still more preferably, the diameter of the second portion 11 is from about 0.100 to 0.150 inch larger than the outside diameter of the feed nozzle 5.

For aluminum and aluminum based alloys, the inside diameter of the first portion 10 of the hole 9 may be set as desired but must be large enough in relation to the outside diameter of the feed nozzle 5 to prevent capillary flow of molten aluminum or aluminum base alloy between the float 2 and the feed nozzle 5. It has been found that preferably the inside diameter of the first portion 10 is at least about three-eighths inch greater than the outside diameter of the feed nozzle 5 and, more preferably, it is at least about one-half inch greater than the outside diameter of the feed nozzle 5.

If the hole 9 had an inside diameter equal to the inside diameter of the second portion 11 throughout its whole length, molten metal might flow by capillary action along the annular gap between the feed nozzle 5 and the hole 9 and would be subject to freezing, thereby immobilizing the float-distributor 1. Therefore, an enlarged hole portion 10 is provided to prevent capillary flow of molten metal between the feed nozzle 5 and the float 2. The shoulder 12 at the juncture of the hole portions 10 and 11 may have any desired shape such as a flat as in FIG. I or a radius as in FIGS. 3 and 4.

The float 2 preferably also includes means 13 for increasing its bouyancy as the flow of molten metal issuing from the feed nozzle 5 increases. This means 13 preferably comprises an inclined portion extending outwardly between the bottom 6 and the wall 8 of the float 2. Where the float 2 has a cylindrical shape, namely, a cylindrical wall 8, the inclined portion 13 will have a conical shape. The inclined portion 13 may extend over the full thickness of the float 2 between the top 7 and bottom 6 portions, thereby, eliminating the wall 8 or any portion of this thickness.

In operation, the float 2 is only partially submerged in the molten metal and only a small portion of the inclined surface 13 is submerged. At high rates of molten metal flow from the feed nozle 5, the float 2 tends to be submerged to a greater extent in the molten metal by virtue of the interaction between the flowing molten metal and the distributor element 3. Therefore, a greater portion of the inclined surface 13 of the float 2 is submerged providing increased displacement and, therefore, increased bouyancy. The inclined surface 13, therefore, provides a novel means for increasing the bouyancy of the float 2 to combat the tendency of the float '2 to submerge under the influence of high holten metal delivery rates issuing from the feed nozzle 5.

For a cylindrical float 2, it has been found that the outside diameter of the float as compared to the inside diameter of the casting mold should preferably be within the limits expressed by the following relationship. The outside diameter of the float 2 should be from about 0.86 X I.D. inch (inside diameter of the mold) 0.81 inch to about 0.98 X I.D. inch 0.82 inch. It has been found that floats 2 having an outside diameter falling within the range delineated by the above relationship have markedly improved stability in the horizontal plane over a wide range of metal flow rates issuing from the feed nozzle 5.

It should also be noted that the float 2 is relatively thin as compared to its diameter having a diameter to thickness ratio preferably greater than 3 to l and, more preferably, greater than 5 to l.

The second major element of the float-distributor l is the distributor element 3 which in accordance with this invention preferably has a conical shape. The cone D has an apex angle a which varies from about 60 to about l50 and, preferably, from about to By varying the apex angle a, metal distribution patterns can be obtained ranging from a substantially horizontal disc type pattern to a cone type pattern. As aforenoted, the more acute the apex angle a, the greater is the tendency of the distribution pattern to drive the molten metal deeper into the casting, thereby, forming adeep cavity with the attendant problems resulting therefrom. Therefore, the 60 minimum apex angle has been chosen as the practical minimum for substantially eliminating the problems associated with distribution cones having highly acute apex angles.

An apex angle a of at least 90 is preferred because the distribution pattern resulting therefrom delivers the molten metal closer to the liquid-solid interface of the ingot as it is being cast.

It has been found that the diameter of the base 14 of the cone shaped distributor D should preferably be sized with reference to the bore 15 diameter of the feed nozzle 5. Preferably, the ratio of the cone base 14 diameter to the feed nozzle bore diameter is from about 1.6 to l to 2 to l.

The depth of the apex 16 of the cone D below the bottom 6 of the float 2 is determined by practice and is dependent to some extent upon the diameter of the casting, the alloy being cast and other casting conditions.

The apex 16 of the cone D is substantially centered about the longitudinal axis of the feed nozzle 5. Greater than usual tolerance to vertical misalignment between the longitudinal axis of the feed nozzle 5 and the cone axis of the cone D is provided by rounding off the apex 16 of the cone D into a substantial spherical surface. Therefore, the distributor element 3 of this invention preferably has a first portion 17 having a conical surface and a second apex portion 16 having a substantially spherical shape. This configuration allows for misalignment between the axes of the cone D and the feed nozzle 5 of as much as 2 to 3 without interfering with the ability of the distributor element 3 to regulate or shut off metal flow from the feed nozzle during cast- The cone shaped distributor D is supported by the float 2 by connecting means 4 which preferably comprises arms 18 connected to the cone D and which pass through the holes 19 in the float 2 and are secured by nuts 20 to the float.

The connecting arms 18 are made as narrow or as small in diameter as possible so that a substantially uniform distribution of molten metal is obtained about the 360 periphery of the mold. it has been found most economical in accordance with this invention to form the connecting means 4 and distributor element 3 integrally as a casting as shown in FIG. 2. This is not meant to be limitive of the invention, however, and the connecting means 4 and distributor element 3 need not be integrally formed but may be separate pieces secured together by conventional techniques.

In the preferred assembly, however, an integral casting is employed with the connecting means 4 comprising the narrow arms 18 which protrude through the holes 19 in the float 2. Flanges 21 are provided on the arms 18 for locating the depth of the cone apex 16 below the float 2. These flanges 21 may be integrally cast with the connecting arms 18 and distributor element 3 or may be adjustable as, for example, the connecting arms 18 could be threaded and the flanges 21 could comprise simple nuts.

It has been found in accordance with this invention, however, that it is more economical and preferable to leave the connecting arms 18 unthreaded and employ in place of threaded nuts, Pal" nuts and Tinnerman speed nuts as are well known in the art. These nuts may be screwed or pushed onto the unthreaded arms 18 to lock them in place in a manner similar to standard threaded nuts on threaded arms.

As shown in FIG. 1, the connecting arms 18 protrude a substantial distance above the top surface 7 of the float 2. The reason for this which will become more apparent with reference to FIG. 3 is to provide means for retaining the float-distributor assembly 1 in position prior to casting.

The float-distributor assembly 1 of this invention has a fairly low metacentric height as compared to floatdistributors previously employed. The low metacentric height of the float-distributor l is obtained because the distributor element 3 preferably has a density greater than or equal to aluminum and more preferably greater than twice that of aluminum and is suspended below the float within the molten metal. It, therefore, acts similar to the keel of a sail boat providing improved stability over a wide range of metal flow rates issuing from the feed nozzle.

The float 2 is preferably formed of a heat resisting material such as Marinite though it may be formed of other materials such as oxidized stainless steel; however, Marinite is the preferred material in accordance with this invention. When formed of a metal such as stainless steel, the float should be hollow to provide adequate bouyancy. The float 2, then, must be formed of a heat resisting material which will not contaminate the metal being cast or it may be coated so as to avoid contamination, and must be sufficiently bouyant to float substantially on the surface of the molten metal.

The distributor element 3 is preferably formed of heat resistant cast iron. However, it may be formed of other materisl as aforenoted having a density greater than or equal to that of molten metal being cast. The use of cast iron is preferred, however, since it provides a very low metacentric height for the float-distributor of this invention and, thereby, the markedly improved stability as aforenoted.

Generally, when a cone D formed of a metal such as cast iron or oxidized stainless steel is used, it is preferably coated to provide increased resistance to erosion by the molten metal flowing about it and to reduce or eliminate the contamination of the molten metal. A suitable coating would be a Whiting sodium silicate wash which comprises precipitated calcium carbonate in water and contains a small amount of sodium silicate as a binder.

Referring now to FIG. 3, the float-distributor 1 of this invention is shown in place in a direct chill cast apparatus prior to the beginning of casting. The direct chill casting apparatus 40 shown therein comprises a table 41 and a novel direct chill casting mold assembly 42 which is the subject of companion patent application Ser. No. 171,461, by LE. Dore and CR. McNutt, filed of even date herewith and assigned to the assignee of the instant invention.

It is preferred that the float-distributor of this invention be employed with the novel casting mold assembly 42 which will now be briefly described. The casting mold assembly 42 comprises a mold liner 43 and a mold manifold 44. The mold manifold 44 contains at least two chambers 45 and 46 separated by an annular web 47 having a plurality of distribution holes 48 substantially equally spaced about it. An inlet, now shown, to the first chamber 45 is provided for connection with a source of cooling medium under pressure. A substantial pressure drop is taken across the distribution holes 48.

The cooling medium is siphoned from the second chamber 46 via a plurality of siphon ports 49 disposed about the internal periphery of the mold manifold 44 and a siphon leg 50 defined by the space between the mold manifold 44 and mold liner 43. The cooling medium is discharged from the siphon leg 50 at an annular discharge slot 51.

This novel direct chill casting mold assembly 42 provides a highly uniform distribution pattern of cooling medium about the periphery of the mold over a wide range of cooling medium flow rates.

The direct chill casting apparatus 40 of FIG. 3 also includes a launder 52 or trough which communicates preferably with a source of molten aluminum or aluminum base alloy. The molten aluminum is discharge from the trough 52 and fed to the mold via a feed nozzle 5.

A cover plate 53 is employed covering the top of the mold liner 43 having hole 54 for the passage of the feed nozzle therethrough and holes 55 for the passage of the connecting arms 18 of the float-distributor l of this invention.

Pal nuts 56 or like means are secured to the connecting arms 18 at a point where they have passed through the holes 55 in the cover plate 53. These nuts 56 provide flanges which support the float-distributor 1 prior to the beginning of casting. A bottom block 57 is employed prior to the beginning of casting in order to form a bottom for the casting mold until the cast metal is sufflciently solidified to begin a drop.

in practice, the molten aluminum from the trough 52 would pass through the feed nozzle and about the distributor cone D and be collected within the space defined by the mold liner 43 and bottom block 57. After the molten aluminum is sufflciently solidified, the casting is withdrawn from the mold liner 43 by the descent of the bottom block 57.

FIG. 4 shows the same apparatus 40 as in FIG. 3 during an actual casting drop. As shown therein, the level of molten aluminum within the mold 43 has risen to a point where the float-distributor is now in floating engagement with the molten aluminum and is no longer supported by the flanges 55 resting against the cover plate 53.

FIG. 4 shows that the molten aluminum level is such that only a small portion of the inclined surface 13 which forms the means for increasing the bouyancy of the float 2 is submerged. The degree of submergence of the float 2 is dependent on the flow rate of molten metal flowing about the distributor cone D. At higher flow rates, the degree of float 2 submergence is greater and the bouyancy of the float is correspondingly increased by virtue of the unique inclined surface, thereby allowing the float-distributor l to operate effectively even at relatively high molten metal flow rates.

In operation, the float-distributor l of this invention regulates the flow of metal issuing from the feed nozzle 5 in correspondence with the level of the molten metal in the mold 43. As the level of the molten metal in the mold 43 increases, the cone D protrudes further into the feed nozzle 5, thereby reducing the molten metal flowing issuing from the feed nozzle. If the height of the metal in the mold 43 becomes sufflciently high, the cone distributor D will completely shut off metal flow from the feed nozzle 5.

As the height of the molten metal in the mold 43 de creases, the cone distributor D protrudes less within the feed nozzle 5 or is completely displaced from the end of the feed nozzle, thereby permitting increased flow rates of metal to issue from the feed nozzle.

Therefore, the float-distributor l of this invention provides a highly effective means for closely regulating the level of molten metal in the mold 43 and is highly effective and stable even at relatively high metal flow rates issuing from the feed nozzle 5.

While the means for connecting the distributor cone to the float has been described with reference to the use of arms, other connecting means as are well known in the art could be employed; however, the use of arms is preferred because they provide maximum mechanical stability combined with small size to provide substantially uniform molten metal distribution around the periphery of the mold.

It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are suitable of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.

What is claimed is:

l. A float-distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising:

float means adapted to float substantially on the surface of said molten metal in said mold, said float means being further adapted to fit about said feed nozzle; said float means including means for increasing the bouyancy of said float means as the flow of molten metal issuing from said feed nozzle increases; and

means supported by said float means for distributing said molten metal about the periphery of said mold and controlling the level of said molten metal in said mold.

2. A float-distributor as in claim 1 wherein said float means comprises a member having top and bottom portions and heaving a hole passing substantially centrally therethrough, said feed nozzle passing through said hole in said float means and wherein said bouyancy increasing means comprises an outwardly extending inclined portion between said top and bottom portions of said float means extending about the periphery of said float means.

3. A float-distributor as in claim 2 wherein said inclined portion extends over only a portion of the thickness of said float between said top and bottom portions and a peripheral wall portion is provided which communicates with said inclined portion and said top portion.

4. A float-distributor as in claim 2 wherein said float means has a cylindrical periphery in correspondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X [.D. inch 0.8] inch to about 0.98 X [.D inch 0.82 inch, where [.D. inch is in the inside diameter of said mold.

5. A float-distributor as in claim 4 wherein the diame ter to thickness ratio of said float means is greater than 3 to l.

6. A float-distributor as in claim 5 wherein said distributing means comprises a cone shaped distributor adapted to be supported below said feed nozzle, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor having an apex angle of from about 60 to about 7. A float-distributor as in claim 6 wherein the apex of said cone shaped distributor has a substantially spherical shape, thereby permitting misalignment between the cone axis and the feed nozzle longitudinal axis of up to about 3.

8. A float-distributor as in claim 7 wherein the hole in said float means has a first portion having a diameter slightly larger than the outside diameter of said feed nozzle and a second portion communicating with said molten metal having a diameter substantially larger than said feed nozzle; whereby said first portion of said hole provides the means for maintaining the position of said cone shaped distributor relative to the longitudinal axis of said feed nozzle and said second portion of said hole provides means for preventing capillary flow of said molten metal between said feed nozzle and said float.

9. A float-distributor as in claim 8 wherein the ratio of the base diameter of said cone shaped distributor to the diameter of the bore of said feed nozzle is from about 1.6 to 1 to 2 to 1.

10. A float-distributor as in claim 9 wherein said cone shaped distributor is formed of a material having a density greater than or equal to aluminum.

11. A float-distributor as in claim 10 wherein said cone shaped distributor is supported by said float by means of a pair of narrow connecting arms which are integrally formed as part of said cone shaped distributor whereby a substantially uniform distribution of molten metal is obtained about the periphery of said mold.

12. A float-distributor as in claim 7 wherein said float means is formed of Marinite and said cone shaped distributor is formed of heat resistant cast iron.

13. A float distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising:

float means adapted to float substantially on the surface of said molten metal in said mold, said float means having a hole substantially centrally therethrough, said feed nozzle passing through said hole and said float means and extending below said float means;

means communicating with said float means for preventing flow of molten metal by capillary action between said float means and said feed nozzle; and means supported by said float means for distributing said molten metal about the peripheryof said mold; said hole in said float means being adapted to maintain accurate alignment between said distributing means and said feed nozzle.

14. A float-distributor as in claim 13 wherein said means for preventing capillary flow of molten metal between said float means and said feed nozzle comprises an anti-capillary peripheral slot between said feed nozzle and said hole in said float means, said peripheral slot being formed by dividing said hole into at least two portions, a first portion having a diameter slightly larger than the outside diameter of said feed nozzle and a second portion communicating with said molten metal in said mold having a diameter substantially larger than said feed nozzle, whereby said first'portion of said hole provides means for maintaining the accurate alignment between said distributing means and said feed nozzle and said second portion defines with said feed nozzle said anti-capillary slot.

, 15. A float-distributor as in claim 14 wherein said distributing means comprises a cone shaped distributor adapted to be supported below said feed nozzle, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor having an apex angle of from about 60 to about l50.

16. A float-distributor as in claim [5 wherein the apex of said cone shaped distributor has a substantially spherical shape thereby permitting misalignment between the cone axis and the feed nozzle longitudinal axis of up to about 3.

17. A float-distributor as in claim 16 wherein the ratio of the base diameter of said cone shaped distributor to the diameter of the bore of said feed nozzle is from about 1.6 to 1 to 2 to l.

18. A float-distributor as in claim 17 wherein said cone shaped distributor is formed of a material having a density greater than or equal to aluminum.

19. A float-distributor as in claim 18 wherein said cone shaped distributor is supported by said float by means of a pair of narrow connecting arms which are integrally formed as part of said cone shaped distributor whereby a substantially uniform distribution of molten metal is obtained about the periphery of said mold.

20. A float-distributor as in claim 19 wherein said float means comprises a member having top and bottom portions and having a peripheral wall portion communicating with at least one of said top and bottom portions.

21. A float-distributor as in claim 20 wherein said peripheral wall portion has a cylindrical shape in correspondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X [.D. inch 0.81 inch to about 0.98 X LD. inch 0.82 inch where I.D. inch is the inside diameter of said mold.

22. A float-distributor as in claim 21 wherein the diameter to thickness ratio of said float means is greater than 3 to l.

23. A float-distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising:

float means for floating substantially on the surface of said molten metal in said mold, said float means being adapted to fit about said feed nozzle; and distribution means supported below said float means,

said distribution means being adapted to be supported below said feed nozzle and comprising a cone shaped distributor having an apex angle of from about 60 to about the apex of said cone shaped distributor being rounded off into a sub stantially spherical surface, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor being formed of a material having a density greater than or equal to aluminum.

24. A float-distributor as in claim 23 wherein the ratio of the base diameter of said cone shaped distributor to the diameter of the bore of said feed nozzle is from about 1.6 to l to 2 to 1.

252A float-distributor as in claim 24 wherein said float means comprises top and bottom portions and a peripheral wall portion communicating with at least spondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X [.D. inch 0.81 inch to about 0.98 X l.D. inch 0.82 inch, where [.D. inch is the inside diameter of the mold.

27. A float-distributor as in claim 26 wherein said float means is formed of Marinite and said cone shaped distributor is formed of heat resistant cast iron.

28. in an apparatus as in claim 24, the improvement wherein said cone shaped distributor is supported by said float by means of a pair of narrow connecting arms which are integrally formed as part of said cone shaped distributor whereby a substantially uniform distribution of molten metal is obtained about the periphery of said mold.

29. Inan apparatus as in claim 28, the improvement wherein said float means comprises a member having top and bottom portions and having a hole passing substantially centrally therethrough, said feed nozzle passing through said hole.

30. In an apparatus as in claim 29, the improvement wherein the hole in said float means has a first portion having a diameter slight larger than the outside diameter of said feed nozzle and a second portion communicating with said molten metal in said mold having a diameter substantially larger than said feed nozzle; whereby said first portion of said hole provides the means for maintaining the position of said cone shaped distributor relative to the longitudinal axis of said feed nozzle and said second portion of said hole provides means for preventing capillary flow of molten metal between said feed nozzle and said float.

31. In an apparatus as in claim 30, the improvement wherein said float means further includes means for increasing the buoyancy of said float as the flow of molten metal issuing from said feed nozzle increases.

32. In an apparatus as in claim 31, the improvement wherein said buoyancy increasing means comprises an outwardly extending inclined portion between said top and bottom portions of said float means extending about the periphery of said float means and communicating with said bottom portion of said float means.

Claims

1. A float-distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising: float means adapted to float substantially on the surface of said molten metal in said mold, said float means being further adapted to fit about said feed nozzle; said float means including means for increasing the bouyancy of said float means as the flow of molten metal issuing from said feed nozzle increases; and means supported by said float means for distributing said molten metal about the periphery of said mold and controlling the level of said molten metal in said mold.

4. A float-distributor as in claim 2 wherein said float means has a cylindrical periphery in correspondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X I.D. inch - 0.81 inch to about 0.98 X I.D inch - 0.82 inch, where I.D. inch is in the inside diameter of said mold.

5. A float-distributor as in claim 4 wherein the diameter to thickness ratio of said float means is greater than 3 to 1.

6. A float-distributor as in claim 5 wherein said distributing means comprises a cone shaped distributor adapted to be supported below said feed nozzle, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor having an apex angle of from about 60* to about 150*.

7. A float-distributor as in claim 6 wherein the apex of said cone shaped distributor has a substantially spherical shape, thereby permitting misalignment between the cone axis and the feed nozzle longitudinal axis of up to about 3*.

13. A float distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising: float means adapted to float substantially on the surface of said molten metal in said mold, said float means having a hole substantially centrally therethrough, said feed nozzle passing through said hole and said float means and extending below said float means; means communicating with said float means for preventing flow of molten metal by capillary action between said float means and said feed nozzle; and means supported by said float means for distributing said molten metal about the periphery of said mold; said hole in said float means being adapted to maintain accurate alignment between said distributing means and said feed nozzle.

14. A float-distributor as in claim 13 wherein said means for preventing capillary flow of molten metal between said float means and said feed nozzle comprises an anti-capillary peripheral slot between said feed nozzle and said hole in said float means, said peripheral slot being formed by dividing said hole into at least two portions, a first portion having a diameter slightly larger than the outside diameter of said feed nozzle and a second portion communicating with said molten metal in said mold having a diameter substantially larger than said feed nozzle, whereby said first portion of said hole provides means for maintaining the accurate alignment between said distributing means and said feed nozzle and said second portion defines with said feed nozzle said anti-capillary slot.

15. A float-distributor as in claim 14 wherein said distributing means comprises a cone shaped distributor adapted to be supported below saId feed nozzle, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor having an apex angle of from about 60* to about 150*.

16. A float-distributor as in claim 15 wherein the apex of said cone shaped distributor has a substantially spherical shape thereby permitting misalignment between the cone axis and the feed nozzle longitudinal axis of up to about 3*.

17. A float-distributor as in claim 16 wherein the ratio of the base diameter of said cone shaped distributor to the diameter of the bore of said feed nozzle is from about 1.6 to 1 to 2 to 1.

21. A float-distributor as in claim 20 wherein said peripheral wall portion has a cylindrical shape in correspondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X I.D. inch - 0.81 inch to about 0.98 X I.D. inch - 0.82 inch where I.D. inch is the inside diameter of said mold.

22. A float-distributor as in claim 21 wherein the diameter to thickness ratio of said float means is greater than 3 to 1.

23. A float-distributor for distributing molten metal and controlling its height in a direct chill casting mold, said molten metal issuing from a feed nozzle associated with said mold, said float-distributor comprising: float means for floating substantially on the surface of said molten metal in said mold, said float means being adapted to fit about said feed nozzle; and distribution means supported below said float means, said distribution means being adapted to be supported below said feed nozzle and comprising a cone shaped distributor having an apex angle of from about 60* to about 150*, the apex of said cone shaped distributor being rounded off into a substantially spherical surface, said cone shaped distributor being adapted to be substantially centered about the longitudinal axis of said feed nozzle, said cone shaped distributor being formed of a material having a density greater than or equal to aluminum.

24. A float-distributor as in claim 23 wherein the ratio of the base diameter of said cone shaped distributor to the diameter of the bore of said feed nozzle is from about 1.6 to 1 to 2 to 1.

25. A float-distributor as in claim 24 wherein said float means comprises top and bottom portions and a peripheral wall portion communicating with at least one of said top and bottom portions, said bottom portion communicating with said molten metal in said mold.

26. A float-distributor as in claim 25 wherein said peripheral wall portion has a cylindrical shape in correspondence to a mold having a cylindrical periphery and wherein the diameter of said float means is from about 0.86 X I.D. inch - 0.81 inch to about 0.98 X I.D. inch - 0.82 inch, where I.D. inch is the inside diameter of the mold.

29. In an apparatus as in claim 28, the improvement wherein said float means comprises a member having top and bottom portions and having a hole passing substantially centrally therethrough, said feed nozzle passing through said hole.