US2698978A - Method for casting continuous ingots of metal or alloys - Google Patents

Description

Jan. 11, 1955 A, s. WELBLUND 2,

METHQD F OR CASTING CONTINUOUS INGOTS OF METAL 0R ALLOYS Original Filed 001:. 2, 1948 v 2 Sheets-Sheet l l I I I l I i H /i I,

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1955 A. G. WELBLUND METHOD FOR CASTING CONTINUOUS INGOTS 0F METAL OR ALLOYS 2 Sheets-Sheet 2 Original Filedflct. 2, 1948 N n a r a r m a j a W M w m United States Patent METHOD FOR CASTING CONTINUOUS INGOTS OF METAL OR ALLOYS Albert George Welblund, Sudbury, Ontario, Canada, as-

. signor to The International Nickel Company, Inc., New

York, N. ,Y., a corporation of Delaware Original application October 2, 1948, Serial No. 52,574. Divided and this application June 8, 1951, Serial No. 230,956

Claims priority, application Canada June 4, 1948 3 Claims. (Cl. 22-2001) The present invention relates to the art of continuous casting of metals and alloys, and more particularly to an improved method of casting in a vertically split mold and an improved method of vibrating the mold sections in a manner to eifect a more eflicient casting operation.

The present invention contemplates an improved method of continuous casting in which sticking or ad herence of solidified metal to the Wall of the mold is effectively prevented by the use of a divided mold whose sections are given a relatively slight but rapid vibration substantially transverse to the direction of motion of the casting or shape.

A further object of thepresent invention is to provide an improved method for reciprocating the oppositely positioned, vertically split and mating mold sections for continuous casting.

Another object is to provide an improved method of producing a continuous ingot, shape or casting of metal or alloy in a vibrating sectional mold.

It is likewise within the contemplation of the present invention to provide a method for reducing to a minimum the average variation in the cross-sectional dimensions of finished ingots, castings or shapes produced in continuous molding apparatus.

Moreover, the present invention provides an improved method of manipulation or working of the metal during solidification in the continuous casting and offers substantial and important advantages over the prior processes and machines as heretofore employed in continuous casting operations.

The present invention also contemplates the provision of faster and more efiicient cooling of the solidified shapes within the mold cavity.

Important features of the present invention which materially contribute in obtaining the advantages aforesaid comprise a special sectional mold structure having vertically divided sections, each of which is supported at its lower end portion on a pivotal bearing to permit of oscillatory vibrational movement and mechanism for vibrating the sections having articulated connection to the upper end portions of the mold sections. The associated arrangement in operation provides that the amplitude of vibrational movement at the upper part of the mold shall be at its maximum with a decrease gradually towards the lower part of the mold. In consequence, the vibrational working of the metal as it passes through the mold and is progressively cooled therein is with a maximum of vibrational movement at the hotter or entering end of the mold and with a minimum or negligible vibration at the lower or discharge end thereof thus to attain a progressively closer proximity of the metal, as it cools and solidifies, with the mold wall so that better cooling is obtained.

The foregoing and other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawing, in which:

Fig. 1 is an elevational view of a vertically split, sectional mold casting machine embodying the features of the invention;

Fig. 2 depicts a plan view of Fig. l; and

Fig. 3 illustrates an enlarged detailed elevational view, partly in section, of the improved sectional mold and oscillating mechanism embodying the present invention.

2,698,978 Patented Jan. 11, 1955 Generally speaking, the present invention comprises a continuous molding machine having a plurality of mating sections forming a vertically-split mold which is provided with means near the upper extremities of the mating sections for vibrating the sections radially to and away from each other and which is provided with cooperating means near the lower extremities of the mating sections for pivotally supporting the sections and for maintaining said lower extremities in substantially constant spaced relationship.

According to the improvement embodying the present invention, each mold section is supported by two ball or roller bearings located one on each side of the section at the lower extremity thereof, and the vibrating linkage is attached to the top of the mold section through a ball and socket joint. By this arrangement, an oscillatory movement diminishing in amplitude from the top to the bottom may be imparted to the die sections around the supporting bearings.

Referring now to Figs. 1 and 2, it will be seen that the machine comprises a base pedestal 1 which supports a split mold assembly by means of adjustably mounted pivotal bearings supported at each side on the pedestal casting. Since the embodiment of the present invention is illustrated and described in conjunction with a vertically split mold in which two oppositely disposed mating sections 7 are used, it is only necessary to provide vibration and oscillation to each of the mating sections. For this purpose, the pedestal is provided with feet 2 and shelves or platforms 3, 3-0, and 3-b, and gear boxes 4 are supported on the platforms. Each of the gear boxes 4 is connected to transmitmotion to an associated mold section by means of a vertical drive shaft 5 carrying an eccentric head 6 at its upper end with operating connections to a mold section supporting member. It will be apparent that the vertically split mold could be made up of a great number of mating sections, for example, four mating sections, by providing additional gear boxes on the platforms 3a and 13-h with suitable provision of associated additional eccentric heads.

In accordance with the present invention, yokes 8 constituting movable supporting members for the mating mold sections 7 are articulated with the eccentric heads 6 by some form of suitable universal joint 9. The lower extremities of each yoke 8 are supported at each side thereof in pivotal bearings 10 wherein the lower ends of the yokes 8 and the mating sections oscillate simultaneously with the reciprocation of the upper ends of the yokes. Means are provided for radial adjustment of the yokes whereby the clearance between the mating mold sections at the lower extremity thereof may be increased or decreased, and this means consists of a bearing arm 11 integral with the female half of the rocker bearing 10, a head 20 rigid with the arm, a thrust bearing guide 14 on an adjusting screw 17 having threaded engagement with the head 20 whereby the head may be moved back and forth by means of an operating mechanism consisting of a crank shaft 12 having a bevel gear 18 thereon and a meshing pinion gear 18-a on the shaft of adjusting screw 17. Since the head 20 is welded or otherwise rigidly secured to the bearing arm 11, any movement of the head 20 will produce a corresponding movement in the bearing arm 11 and a corresponding displacement of the yokes 8 and the mating sections 7 will be effected through the rocker bearing 10. Any particular setting of the yokes 8 as made by the radial adjustment means is maintained by means of the guide clamp 13 which is adapted to clamp tightly to the bearing arm 11 and the thrust bearing clamp 14 having a bearing therethrough for the adjusting screw 17. The bearing arms 11 are adapted to slide along a slot 21 in the sides of a crossbase 22 when the adjusting screw 17 is rotated. The

casting operation. The efliciency of heat transfer from thehot ingot to 'the circulating coolingfiuid is advantageously affected in the improved machine of the present invention as hereinafter described.

The mating sections 7 of the dynamic 'mold are vibratedincoordination with eachother and, in the closed position, it is preferable that they mate so closely that there is substantially no clearance between them although they preferably do not actually'touch. The vibrations may be imparted to the sections in any appropriate manner, such as mechanically,electrically, pneumaticallyor the like. A suitable mechanical means therefor is shown in Fig. 3. In this figure, rotating eccentrics, in-

' dicated generally by the reference numeral 24, are provided on the upper end of shaft5 within an eccentric head 6 which is supported by roller bearings on the eccentric shaft end. The rotating eccentrics are adapted toimpart reciprocating motions to the-mating sections 7 through connecting rods'25 and the yokes 8. Each connecting rod'is connected at itsouter end to an annular member 28 of the eccentric assembly by means of a cross-head 26 pivotally connectedto member 28 by a wrist pin 27. The cross-head 26 is provided with. a drilled and tapped hole into which a correspondingly threaded end of the connecting rod is screwed. The opposite end of the connecting rod 25 is provided with a balled end 25 which is retained within a socketed projection on the yoke 8 to form a ball and socket joint. A nut 29 provides for locking the rod in its adjusting position. The eccentric head 6 comprises the upper, outer annular member 28 and a lower, rigidly supported bearing housingsection 30. The annulus 28 is rabbeted on its inner surface to provide a shoulder on which an outer race 31 of a ball bearing 32 may rest, in which position it is firmly held by ring clamps 33 and cap screws 34. Upper member 28 is closed by a cover plate 35 secured to the ring clamp 33. The lower section 30 and upper member 28 are annularly tongued and grooved on their opposed faces, with play being provided between the tongue and groove in amount exceeding the maximum throw of eccentric 24. Upper member 28 is thus free for horizontal'movement in any direction but, at the same time, is-retained in position relative to the lower housing section 30.

The bottom of lower section 30 is closed by a bottom cover 36 fastened thereto by cap screws 37. The bottom cover preferably comprises a main plate 36-a, a packing ring 36-!) which may be of felt, asbestos, rubberized asbestos and the like, and a retaining ring 36-c, all held together by machine screws 36-d. The packing ring 36b tightly engages the shaft 5 to prevent escape of lubricating agents from lower section 30.

Each shaft 5 is provided with a collar 38 on the upper surface of which the inner race 39 of ball bearing 32'is supported and is retained in supported position by a flanged eccentric ring 40 and a disc 41. Against the lower surface of the collar 38, a lock'nut 42'holds an inner race 43 of a ball bearing 44, the outer race 45 of which is secured in any appropriatemanner'to the inner wall of lower section 30. The upper end 46 of shaft'5, which extends beyond collar 38, is eccentric with respect to the axis of the shaft 5. The inner and outer walls of eccentric ring 40, which fits down over the eccentric end 46, are eccentric with respect to each other. Eccentric ring 40 may be rotatably adjusted with respect to the end 46 and thus the amplitude of the reciprocating motion which is imparted to cross-head 26 may be varied. Means for locking eccentric ring 40 in any desired position on end 46 comprises a set screw 47 adapted to be inserted through disc 41 into one of a plurality of holes provided in the top of ring 40. The disc 41 is. secured to the end 46 of shafts 5-a by two or more cap screws, and eccentric ring 40 is thus rigidly secured in the described adjusted position on the eccentric end 46 of the shaft 5. Vertical displacement of upper section 28 is also thus controlled.

Rotation of the shaft 5 may be by any appropriate means such as an electric motor (not shown). The motor is arranged to rotate the shaft 48 through any appropriate means. The shafts 5 and 48 are provided with meshing bevel gears 42 and 50 keyed to the respective shafts. These bevel gears and the shaft ends to which they are keyed are enclosed within the gear box 4. The shafts 5 and 48 are providedwith suitable bearings 51 and oil seals 52 are also provided to retain gear lubricant with which the gear box 4 is filled.

The machine is put into operation by starting the circulation of cooling water'throughthe cooling'channels'23,

moving the mold sections 7 to the minimum clearance and introducing molten metal into the mold after first closing off the mold cavity by the insertion of a dummy bar. Adjustment of the eccentric to the desired throw willhave previouslybeen'made by the radial'adjustment means hereinbefore described. The starting dummy bar and following ingot as cast are supported in the customary manner by driven'supporting and withdrawing rollers 61 and 62 positioned below the mold assembly and conventionally shown in Fig. '3. Any satisfactory structure may be employed, but it. is preferred to use the adjustable pressure-structure and arrangement disclosed in U. 'S. PatentNo. 2,284,704 dated'June 2,1942.

It has been found that satisfactory results are obtained by vibrating the mold sections from about .to about 1500 times per minute and having them move a very small distance, for example, :about two-thousandths to about SO-thousandths of an inch. It will be noted, however, that according to the'present invention, this'reciprocating movement of the mating sections .will take place largely at the upper extremities thereof and with the lower extremities of the fold-sections remainingsubstantially vat the setting 10f .minimum clearance. Expressed otherwise, it will be seenthat the vibration of the mold sections according to the present invention is a vibrating oscillationthereof from a pivotal support near the lower extremity of each mating section and, hence, varies in magnitude from a maximum throw at theitop of the mating section toea minimum of substantially no throw at the lower extremities of the mating sections.

-Itis to be:n0ted, in the methodv and machine embodying the present invention,:that withthe lowerextremities of the mating sections remaining substantially at the setting of minimum clearance, the inner wall surfaces of the mold sections are continually maintained in close proximity tothe metal of the casting. As a result, there is a marked increase in the efliciency of cooling, with faster cooling and solidification of the shape. The higher efficiency of cooling permits fasteroperation since, as is wellknown in-continuous casting operations, therate of input of molten metal and the rate of withdrawal of the solidified ingot must be coordinated, and both are largely dependent on the rate of solidification andcooling. of the metal within the mold cavity.

The method and machine embodying the present inventionproduce many advantages over the prior art and likewise provide improved characteristics in the finished ingot. Thus, for example, the following maybecited as illustrative: (1) progressively decreased compression of ingot with solidification; (2) lower mean variation in cross-sectional dimensions; and (3) more efiicient-cooling of ingot within the mold. Moreover, as shown in Fig. 3, a further cooling ofthe finished ingot as it emerges from the mold in-its passage to the withdrawing rolls is effected by means of water sprays directed against the ingot from the cooling device'63.

Thepresent application is a division of applicantscopending prior application, Serial No. 52,574 filed October 2, 1948, which issued as Patent No. 2,578,213.

Although the present invention has been described in considerable detail with respect to a preferred embodiment, it'will be understood thatmodifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications .and variations are considered'to be withinthe purview and scope of the invention and appended claims.

I claim:

1. A method of producing a continuous ingot, shape or casting of'metal alloy in a substantially vertically-disposed vibrating-sectional mold, which comprises pouring metal in a molten state into the upper end of said mold thereby establishing a substantially vertically-disposed body of metal within the mold, vibrationally working said metal by applying opposed pulsating compressive forces to a major partof the area of the substantially verticallydisposed external surface of said body as-it passes downward" through the moldjthe distances through which said pulsating forces are applied decreasing from a maximum adjacent the upper end of the mold to a minimum adjacent the lower endof the mold, whereby .better control of the cross-sectional dimensions and surface characteristics of the solidified ingot is obtained than when the distances through which the compressive forces are applied are the same throughout the length of the mold, and substantially continuously withdrawing the thustreated solidified metal from the lower end of the mold.

2. The method of producing a continuous ingot, shape or casting of metal or alloy, which comprises introducing metal in a molten state into a mold chamber having an entrance end and an exit end, vibrationally working said metal by applying opposed pulsating compressive forces to a major portion of the surface of the metal as it passes through said mold chamber, the distances through which said pulsating forces are applied decreasing from a maximum for each of the forces applied adjacent the entrance end of the mold chamber to a minimum for each of the forces applied adjacent the exit end of the mold chamber, whereby better control of the cross-sectional dimensions and surface characteristics of the solidified ingot is obtained than when the distances through which the compressive forces are applied are the same throughout the length of the mold chamber, and substantially continuously withdrawing the thus-treated solidified metal from the exit end of the mold chamber.

3. The method of producing a continuous ingot, shape or casting of metal or alloy, which comprises introducing metal in a molten state into a mold chamber having an entrance end and an exit end, vibrationally working said metal by applying opposed pulsating compressive forces to a major portion of the surface of the metal as it passes through said mold chamber, the distances through which said pulsating forces are applied progressively decreasing from a maximum adjacent the entrance end of the mold chamber to a minimum adjacent the exit end of the mold chamber, whereby better control of the cross-sectional dimensions and surface characteristics of the solidified ingot is obtained than when the distances through which the compressive forces are applied are the same throughout the length of the mold chamber, and substantially continuously withdrawing the thus-treated solidified metal from the exit end of the mold chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,131,307 Behrendt Sept. 27, 1938 2,284,704 Welblund et al June 2, 1942 2,290,083 Webster July 14, 1942 2,376,518 Spence a May 22, 1945 2,503,819 Gunn et al Apr. 11, 1950 2,578,213 Welblund Dec. 11, 1951 FOREIGN PATENTS 102,995 Sweden Nov. 11, 1941 480,412 Canada Ian. 22, 1952

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