US2466277A - Method of casting - Google Patents

Description

April 1949-, G. A. ausls'scsw 2,466,277

METHOD OF CASTING :s Sheets-Sheet 1 Filed March 26, 1945 @W l/ZJZJJM a -G A. RUBI SSOW April 5, .1949.

METHOD OF CASTING :s Sheets-Sheet 2 Filed March 26, 1945 April 5, I949. G. A. Rualssow I 2,466,277-

METHOD OF CASTING Filed March 26 .1945 3 Sheets-Sheet 3 I mora nes. 11 s METHOD or cas'rmo George A. Rubissow, New York, N. Y.

.' Application March 28, 1945, Serial V 3 Claims. (01.,22-2005) This invention relates to the casting of materials which may benefit from being subjected to centrifugal action while in the mold. Metals are among the most important of such materials. It has for an'object to produce the beneficial effects on the castingobtained by subjecting the molten material in the mold to centrifugal force and particularly to the action of such force alternately between mold tri'iugal machinery.

In accordance with therefore, the mold, either after the molten material has been placed therein, or also during the flow of the molten material thereinto, is sub- Jected to an oscillatory arcuate up and down motion under the influence of gravity, such motion imparting the desired centrifugal action to the mold and its contents. This oscillatory motion may be a true pendulum motion, or it may be more or less modified as may be found desirable.

By way of example, certain embodiments of the invention are illustrated in the accompanying drawings, in which Figure 1 is a diagrammatic side elevation oi a casting machine constructed in accordance with and embodying the invention.

Figure 2 is a top plan view of the same.

Figure 3 is a view similar to a portion of Figure 1, but showing a modification.

Figure 4 is a fragmentary view partly in -section on line d-t of Figure 3 and partly in elevation.

Figures 5 and 6 are somewhat diagrammatic views illustrating booster means forimparting a swinging impulse to the mold and related parts.

Figures 7 and 8 are somewhat diagrammatic views illustrating difierent means for rotating the mold and related parts during its oscillation.

Figures 9 and 10 are views similar to a portion 01' Figure 3, but showing further modifications.

Figure 11 is a view similar to Figure 1, but showing a still further modification.

Figures 12 and 13 are diagrammatic views illustrating modified paths of motion for the mold and related parts.

Figures 14 and 15 are diagrammatic views illustrating the angle of swing and the corresponding centrifugal force developed for pendulum motion under the action of gravity.

Figure 16 is a side elevation of a pendulum apparatus 01' a diii'erent construction.

Figure 17 is a view of apivotal connection bethe present invention,

tween the pendulum arm and the mold casing, partly broken away and in section.

Figure 18 is a view partly in section and partly in elevation showing a modified ladle and pouring gate construction.

Figure 19 is a sectional view on line iii-i9 of Figure 18.

Figures 20 and 21 are side and end elevations, respectively, showing a double pendulum mounting for a mold casing.

Referring first to Figures 1 and 2, a casing i is shown as suspended as, by a chain or cable 2, which passes about or over a fulcrum bar 3 carried by a support l, the arrangement being such that the casingl is permitted to swing about the bar 3 as a center in pendulum motion. One or more molds 5 are supported in the casing and a ladle 6 is also carried thereby and normally positioned above the mold 5. The ladle communicates with the mold through a valved gate 6a, so that molten material carried within the ladle 6 may be caused to fiow by gravity into the mold when a closure plug 1 for the gate 8a is retracted. The ladle is shown as provided with a top filling opening 8 through. which the molten material to be cast in the mold may be introduced thereinto. The casing may have a removable side to permit removal and replacement of the molds, and, ii desired, also, of the ladle, or the ladle may be a part of the casing.

As shown in Figure 1, the casing containing the mold and the ladle may be swung upwardl and there held as by suitable latch means includingthe hook 8 secured to the ladle and a pivoted hook it fulcrumed on the support 4. This hook I0 may be released, when desired, as by pulling a release rope il secured to the hook it. The casing may be swung up to this position by any suitable means such as a hoisting rope l2 which passes over a pulley ia journaledon the frame 4 and extends down to an eye I on the casing.

When' the casing is in its uppermost position as shown in full lines inFigure 1, theladle may be filled with molten material. been accomplished, the casing may be released so that it may swing as apendulum about the axis 3, and at a suitable point in its swing, the plug 1 may be withdrawn, allowing the molten material to pass from the ladle into the mold. This release oi the molten material may be accomplished by withdrawing the plug 1, this plug being shown as having attached thereto a flexible cable i5, and this release may be made automatic by securing the upper end'of the cable II to a When this has i part I. secured to the pivot 8 in such position t at as the casing reaches substantially the lowest portion of its swinging motion, the plug 6 is pulled upwardly and then latched open as by the spring dog Ia which may engage the top of the casing.

If desired, an impulse in addition to gravity may be applied to the of swing. As shown in Figure 1, this may be accomplished by the actionof a coil spring 20 which is compressed when the casing is swung upwardly to its full starting position. When the, casing is released, this spring adds to the force of gravity, tending to swing the ladle.

' The casing may be swung in a central path in a single plane as in the plane of Figure 2, or it may be constrained to follow a path having horizontal as well as vertical components, following the lines o, d, e, b, j, g, a, as shown in Figure 2 as by starting the swinging motion from a posi tion at one side of the vertical plane containing the suspension point. The ladle and valve for it may be omitted if desired in any case, and the molten material poured into the mold through the usual pouring gate.

Other means of imparting an initial boosting force to swing the mold and related parts are shown in Figures 5 and 6, Figure 5 showing an air pressure cylinder 21 having apiston 22 therein, the rod 23 of which engages the casing, and through the pressure applied back of the piston 22, gives it a push at the moment of release. In Figure 6, electro-magnetic means 24 is illustrated for the same purpose, the 'energization of the electromagnet forcing an armature plunger 25 against the casing. This may be energized from a suitable power source by the closing of a switch at 26 when the movable latch 21 is caused to release the casing.

The effect of the pendulum motion istc produce centrifugal force in accordance with the diagrams of Figures 14 and 15, the centrifugal force PX being represented for the point of a,'=0 by the following formula:

wherein n is the height from the lowest point of swing (0 position in Figure 14) to the position 9: from which the molten material in the mold swings. For example, It for a 90 swing is equal to the radius r and for a 60 swing it is equal to ,61. W is the weight of the molten or solidified material. V

When the starting angle is about 60 from the vertical, the centrifugal force is about double the weight W of the molten material or the same material after solidification.

When the starting point is about 70 from the vertical, the centrifugal force is about 2.5 times W, and at 80? from the vertical, the centrifugal force is close to three times the weight.

From this it will be seen that centrifugal force increases rapidly with the increase of angle from the vertical at which the swing is started. It will also be noted that it is not affected by the length of the pendulum arm. For greater c'entrifugal force it is therefore important that the angle of swing be large. It is also evident from the formula that the centrifugal force is at its maximum at the'lowest point of the swing. For fullest starting effect of centrifugal force during 'the filling of the mold, therefore, the gate should be opened when thecasing is closest to its lowest position. I

casing to increase the angle 1 The length of the pendulum arm, however, does have a bearing on the time it takes for a complete swing. this being according to the well known law of pendulums, and this is of importance therefore in determining how many swings or oscillations will be made in a given time and therefore how many centrifugal force impulses will be exerted on the material in the mold before it solidifies. It is of further importance because the effective length of the pendulum is determined by the position of the center of mass of the entire swinging organization, and the position where the centrifugal force is effective on the casting may or may notcoincide with the center of mass. Thus, if the position where the centrifugal force to be used is located further from or nearerto the fulcrum, than is the center of mass, the centrifugal force to which the material is subjected will be correspondingly greater or less due to its greater or less velocity than if it were located at the center of mass. Thus by locating the center of mass nearer to the fulcrum, as by attaching a weight W (Figure 3) to the pendulum arm above the mold, the time for each pendulum swing may be reduced, 1. e. the frequency of swing increased with consequentiacrease of maximum velocity and centrifugal force in the mold. By this means the maximum centrifugal force may be increased as much as two or three times compared with a pendulum structure having the same swing radius for the mold but with its center of mass located within'the mold. Adiustment'of the position of the added weight W above or below the mold thus affords a ready means for adjusting the maximum centrifugal force at the casting position for any given are of swing and distance of the mold from the swinging axis.

In Figure 15 is shown a diagram of the centrifugal force developed, which, it will be noticed, is greatest at the point of the swing where the casing is in its lowest position.

In Figure 3 is shown a modification in which instead of employing a flexible suspension means such as 2, shown in Figures 1 to 6, the suspension means comprises a rigid arm 30 (Figures 3 and 4). Likewise in these figures the ladle 31 is illustrated as pivotally supported at 32 within the casing and is so arranged that when it is tilted upwardly into the dotted line position of Figure 4, an opening 83 therein is brought into registry with the gate 34 of the mold 5a so as to pour molten material thereinto. The ladle may be tilted to .discharge position by any suitable means, bu as shown in Figures 3 and 4, this is done by pulling upon a cable 36 secured at one end to an eye 88 on the ladle and having its opposite end secured to a winding drum 31 Journaled, as on the bearings 38 carried by the fulcrum shaft 39, from which the casing la is shown as suspended. The drum 31 may be provided with a bevel gear portion 40 with which meshes a bevel pinion 4| carried by an actuating shaft 42 journaled in a fixed frame portion and provided with an actuating handle 43. By turning the handle 43, the ladle may be tilted to its discharge position. Also as the arm swings downwardly in the right hand direction shown in Figure 3, the cable is automatically wound on the drum 8'! while the drum is stationary, and may be adjusted with initial slack in the cable so that as the casing approaches its mid-swinging position, the ladle is tilted automatically to its discharge position.

It may also be found desirable to turn the mold as it is being swung, this turning having the efiect to vary the angular relation of the mold to the direction of centrifugal force, or ii the rotation is made suillciently rapid, a subon wheels, is of particular importance where the parts are large and heavy. It also makes possible mold and related parts can be accomplished. In

Figure 7 the casing is shown as provided with a sleeve 50 joulnaled on a rod i which forms the pendulum supporting arm. This sleeve 50 is provided with a gear 52 with which meshes a pinion 53 on the shaft 54 of a motor 55 supported on the arm 5i. When the motor 55 is energized by any suitable means after the ladle has been emptied, it will be evident that the mold casing and its associated parts will be rotated about the axis of the rod 5i, which in this case is radial to the center of oscillation of the mold and related parts about its pendulum fulcrum 56. Wind pressure developedby the swinging action of the mold casing may be availed of to turn the casing about an axis while it is being swung, Figure 8 showing the mold casing lb provided with a series of outwardly extending vanes 60 on its periphery, which as the mold casing is swung, are acted upon by the air through which the casing is being swung, causing rotation of the casing about the swinging axis element 6|.

In Figures 9 and 10 further modifications are shown. In Figure 9 the ladle 10 has such a shape that it may be filled through its top opening 1i while the casing is at one end of its swing, the molten material then failing to flow into the mold through the open gate 12 due to the angular relation of the parts. When, however, the mold is swung downwardly, the molten material in the ladle will flow over into the gate I2 and may be emptied thereinto by gravity and centrifugal force as the ladle continues to swing toward the opposite end of its path of motion from starting position. In Figure 10 a valved gate islempioyed, the valve 15 for the gate being a rotary valve which is connected through an arm 16 fixed thereto and a link TI to such a point that as the casing ic swings downwardly, the gate is opened, allowing the flow of molten material from the ladle 18 through the gate 19 into the mold.

In Figure 11 a further modification is shown in which instead of suspending the casing for pendulum motion, it is formed as a vehicle 80 constrained to oscillate through an arcuate path I by the action of gravity while supported on a suitable arcuate track 8|. As shown the vehicle 80 is provided with a suitable number of wheels 82 to support it and guide itupon the rails 8i. It may be held in elevated starting position, means for so doing being shown diagrammatically as a latch 83 engageable with a part 84 of the vehicle. By retracting the latch 88 the vehicle is released for motion by gravity downward along one side of its supporting way and up the other side so as to pass through essentially a pendulum path. The vehicle 80 may comprise the mold 85 and a ladle 86, the parts being so arranged, as shown, that when the vehicle is in its starting position, the ladle may be supplied with molten material to a point below the entrance of the gate 81 leading into the mold cavity, but when the vehicle 80 approaches the midposition of its path, the ladle and mold are so related that the ladle-discharges molten material into the mold through the gate 81, as will be apparent from an inspection of Figure 11.

The arrangement of a trackway to support the mold and related parts. the latter being mounted modification of the shape of the pathas shown,

for example, in Figures 12 and 13, to provide any desired modification of the time of maximum centrifugal force as related to the timing or I oscillation of the mold and related parts in the complete path. For example, in Figure 12, the path is cycloidal, and in Figure 13 it has straight and curved portions. Any desired curves can be used and will produce for each given point a pressure corresponding to the pendulum load for this point in the curvature corresponding to this part of the curve. The isometriqcycloid shownin Figure 12 is of particular interest as it permits the mold and related'parts to reach center position in a shorter time than does a circular arc.

formula:

where 1 and a: are the vertical and horizontal components.

These arrangements which provide for oscillatory motion of-the mold and related parts during the casting operation isoften of particular value due to the alternate increase and decrease of centrifugal force. The pressures obtainable are suflicient to produce excellent castings. The time of single one way pendulum swing,

I being the pendulum length and g the force of gravity. Assuming that l is three feet, the time of one swing will be approximately 1 second. If, for example, the solidification of the molten material in the mold requires 60 seconds, there will be approximately 30 complete or 60 single swings before the solidification of the molten material is efiected throughout, and this is sufilcient time to centrifugally orientate the crystals and thus create an improved boundary interlock .between the molecules of the crystals in the solidified material.

The swinging of themold may be continued as long as desired, or until the mold and related parts come to rest. Ordinarily it will be desired to continue the swinging motion at least until such time as the molten material has congealed within the mold, although it may be continued until the mold comes to rest.

It may be found desirable in some cases to retain the ladle, or both the ladle and the mold,

substantially horizontal during a part of or all of the oscillatory or swinging motion. Thus in Figures 16 and 1'7, the mold casing is shown as pivoted to the pendulum arm at I00 so that the casing may hang substantially horizontal while the arm is swung up to its starting position as shown in Figure 16 in full lines. As the casing on the first swing approaches its lowest position, a spring latch iill snaps into the notch I02 on the casing and locks the arm and casing together so that thereafter the casing will remain in the same angular relation to the pendulum arm throughout the remainder of its swinging motion, as shown in broken lines in Figure 16.

In Figures 18 and 19 the mold casing is shown sprocket wheel H3 fixed respect to the sup- This curve may, for example, have the port and concentric with the pendulum axis H4. Thus as the pendulum swings, the sprocket wheel III is caused to oscillate in time with the swinging motion and at such a rate, sprocket wheels ll and H3 being of equal size, that the. mold casing is held in fixed angular position. In case that aladle H5 is used, it may be closed by the valve H6 and this may be retracted at the desired part of the swing bythe action of a cam H1 across which the upper end of the valve actuating lever I I8 passes during the swing. A spring pressed pin I engaging the lever 8 tends to close the valve H6, while a spring latch l2l holds this valve open after it has once been opened, until it is released by the operator In order that the casing maybe started to swing from its lowest position rather than starting the swing from an elevated point, the cam H1 may be swung up into the'dotted line inoperative position of Figures 18 and 19 where it may be releasably held as by a latch I22. By releasing this latch, cam

-il'| may swing downwardly into operative position at the proper time in the swing after the desired amplitude of swing has been obtained.

In Figures 20 and 21, another arrangement for maintaining the casing horizontal throughout the amplitude of swing is illustrated, wherein a pair' of spaced links 125 pivotally suspended at their upper ends on parallel axes pivotally support the casing at their lower ends. Weights I28 are shown as adjustably secured to the links I for adjusting the center of pendulum mass from and toward the fulcrum as may be desired, to thus adjust the rate of swing and the centrifugal force exerted on the molten or cast material.

It will also be understood that before, during, or after the casting the material may be sub- Jected to controlled heating, as by electric heating elements of any type suitable for the material being cast, the wires I30 for which may lead into the casing through or along the pendulum arms or links as shown in Figure 20.

If desired, also, the mold may be filled wniie stationary in its lowest position and then the swinging motion be initiated.

From the foregoing description of certain embodiments of this invention. it should be evident to those skilled in the art that various furtherchanges and modifications might be made without departing from the spirit or scope of this invention.

I claim:

1. A to and fro pendulum casting method for casting of molten material into a mold comprising: pouring said molten material into said mold while said mold is at standstill, thereafter letting said mold automatically swing freely to and fro between the respective intermittent left and right pendulum swinging positions of said mold while the amplitude between said swinging positions is self-regulated by the action of the force of gravity exercised by the weight of said mold with said molten material therein.

2. A to and fro pendulum casting method for casting of molten material into a mold comprising: pouring said molten material into said mold while said mold is at standstill and is coincidin with the horizontal axis of oscillation, thereafter letting said mold to automatically swing freely to and fro between the'respective intermittent left and right swinging positions of said mold while the amplitude between said swinging positions is self-regulated by the action ofthe force of gravity exercised by the weight of said mold with said molten material therein.

3. A to and fro pendulum casting method for casting of molten material into-a mold comprising: pouring said molten material into said mold while said mold is at standstill, thereafter letting said mold automatically swing freely to and fro between the respective intermittent left and right pendulum swinging positions of said mold while the amplitude between said swinging positions is self-regulated by the action of the force of gravity exercised by the weight. of said mold with said molten material therein, thereafter at least once forcibly increasing said amplitude, thereby prolonging the duration of application of said method.

GEORGE A. RUBISSOW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 469,131 F'reid Feb, 16, 1892 924,133 Morse June 26, 1908 1,010,851, Bruckmann Dec. 5, 191i. 1,080,224 Latcher Dec. 2, 1913 1,366,875 Collignon Jan. 25, 1921 1,400,857 Bloom Dec. 20, 1921 1,419,280 McNeill June 13, 1922 1,908,104 Bell May 9, 1933 1,949,021 Leuser Feb. 27, 1934 1,992,880. Nilsson Feb. 28, 1935 2,216,567 Esnault-Pelterie Oct. 1, 1940 2,325,019 Rubissow July 20, 1943 FOREIGN PATENTS Number Country Date 399.331 Great Britain Oct. 5. 1933 290,833 Germany Mar. 20, 1916

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