US1429807A - Centrifugal casting machine - Google Patents

Description

I. v, TURNER. CENT RIFUGAL CASTING MACHINE APPLICATION FILED SEPT. 29, 1921. 1,429,8U7u Patentedsept- 19', 1922. v

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CENTRIFUGAL CASTING MACHINE.

h APPLICATION FILED SEPT. 29, I921. 1,429,807; I Patentedfiept- 19,1922.

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barren stares JOSEPH V. TURNER OF WILSON, NORTH CAROLINA.

GENTRIFUGAL CASTING MACHINE.

Application filed September 29, 1921. Serial No. 504,165.

T 0 aZZ 1071021211 may concern Be it known that I. JosEPH V. TURNER, a citizen of the United States. residing at Vilson, in the county of lYilson and State of North Carolina, have invented new and useful Improvements in Centrifugal Casting Machines, of which the following is a specification.

This invention relates to centrifugal casting machines and has for its principal object the provision of a simple and eflicient device more particularly adapted to casting dental iilillay fillings and other articles of irregular s ape.

A more specific object of the invention is to provide a device-of the class described having a rotatable arm and an investment crucible arranged in operative relation thereto, said crucible being movable relative to said arm around two axes arranged at right angles to one another so that the position of the cup at any time during the rotation of the device is the component of the positions assumed by said cup with respect to each of said axes.

Another object of the invention is the construction of a centrifugally actuated combined crucible and investment flask in which the material of which the inlay filling is to be made is both melted and cast, so as to provide a minimum path for the molten globule from the crucible to the mold with a view to conserving the heat of the molten globule so that it will be in a freely fluent state when it enters the mold, in order to ensure its entry into the smallest interstices of the pattern cavity. 1

Another object of the invention is the provision of a centrifugal casting machine having an arm rotatable in a horizontal plane and an investment flask arranged in operative relation. to said arm and capable of movement relative to said arm through the influence of centrifugal force said arm and investment flask being so connected that should the rotary movement of said arm be suddenly arrested the action of centrifugal force on said investment flask will be continued for a time due to the independent rotation of said flask about the connecting means.

Vith the above and other objects in view, my invention consists in the improved centrifugal casting machine illustrated in the accompanying drawings, described in the following specification, and particularly in position.

claimed, and in such variations and modifications thereof as will be obvious to those skilled in'the art to which my invention relates.

In the drawings accompanying and formmg in the preferred embodiment of, my invention is illustrated:

Figure 1 is a view in perspective showing one embodiment of my improved centrifugal casting machine.

Figure 2 is a side elevation of the horizontal arm of the machine shown in Figure l with the associated parts.

Figure 3 is a side elevation of a modification of the machine.

Figure 3 is a perspective view of a modification of the invention embracing the construction of both Figures 1 and 3.

Figures 4 and 5 are respectively a side elevation and a plan view of still another modification.

Figure 6 is a view in cross section of the combined crucible and investment flask.

Referring now particularly to the modification shown in Figures 1 and 2 the numeral 1 is used to designate a clamp or vise having spaced jaws 2 and 3 adapted to engage opposite surfaces of a shelf or table and having a clamping screw 4 cooperating with one of said jaws to secure said clamp Said clamp is apertured vertically for the reception of a shaft 5 on the lower end of a part of this specification, and where-- which is a bevel gear 6 which meshes with a bevel gear 7 journalled on a pin 8 which is mounted on the front surface of said clamp.

A hand crank 9 issecured to the bevel gear 7 by means of which said gear and the shaft 5 are rotated.

Mounted upon the upper end of the vertical shaft 5 in any suitable manner is a horizontal arm 10, carrying at one end a vertical stub shaft 11 on which is journalled the hollow sleeve 12 which is integral with or otherwise fixedly secured to the yoke 13 having the bifurcated ends 14: and 15. Journalled in axially arranged bearings in the bifurcated ends of the-yoke member are the offset ends 16 of an open bail having the supporting arms 17 and 18 which are attached at diametrically opposite points to the retaining ring 19.

A cylindrical metallic receptacle extends freely through the ring 19 and is seated on the upper surface thereof by means of an sit ion of adjustment.

Figure 6.

. the shaft 5 outwardly extending flange 21, best shown in This receptacle functions as a combined crucible and investment flask as will presently appear, and is provided. with numerous perforations both in the sides and bottom, to permit the escape of steam and other vapors from the investment compound when it is heated.

Slidably mounted on the opposite end of the horizontal arm 10 is the adjustable counterbalance weight 22 carrying a set screw 23 by Which it may befixed in any po- The function of the counterbalance weight is to equalize, as nearly as possible the weight on each side of and thus minimize undesirable vibration of the parts when the shaft is rotated.

The preparation of the matrix within the investment flask is done in the usual manner by supporting the pattern of the inlay filling, made of wax or other readily fusible material within said investment cup by means of a fusible pin. Plaster of Paris is then poured around said pin and pattern. When the plaster has set the investment flask is inverted and heat applied thereto which melts the pattern and pin permitting the substance of which they are composed to drain from the investment leaving thereina hollow cavity of the identical shape of the pattern, connected with the upper surface of the investment I by a narrow: opening or. sprue. As the investment flask is to be used also as a crucible in which to melt the material of which the inlay flllingis to be made. it is hollowed into a slightly rounded or conical depression. When this stage of procedure has been reached the investment flask is placed Withinv the ring 19 with its flange 21 resting upon the ring, and a sutficient quantity of the material of which the inlay is to be made is placed within the depression in the plaster of Paris investment. The blow pipe is then directed upon said material and it is brought to a molten state. At once the handle 9 .is grasped and the device given a few rotary movements. Through the agency of centrifugal force thus set up the molten globule of material is forced through the sprne into the pattern cavity in the matrix. On account of the fact that the heat from the blow pipe also preheats the investment and that the path through which the molten globule must travel from the point where it is melted to the pattern cavity is short the heat of said globule will be conserved so that said globulc will enter said cavity in a freely fluent state and will by the action of centrifugal force be pressed into, the smallest interstices of the pattern cavity. This entrance of the globule is facilitated by the air within said cavity having been rarefied and expelled by the heating of the investment so that very little displacement of air is required to make room for the moltenmaterial.

One of the difliculties attending the use of a device of this character is the avoidance of spilling the molten globule of material during the act of rotation. Qlhere are two forces acting upon the molten globule at that time. One is the force of inertia which tends to cause said globule to remain where it is relative to'space, and the other, centrifugal force, which'tends to cause said globule to move in a path radially of the axis of rotation of the shaft 5. Where the globule will be at any moment during the rotative act depends upon the relative strength of these forces at that particular moment, and it is essential that the investment flask shall at all times assume and maintain a position be hind the globule with the surface of the depression in the top of said flask perpendicular to the path in which the latter tends to move. In order to satisfy these conditions I have provided means by which said invest ment flask is independently rotatable relative to two axes lying at right angles to each other, one being the axis of the stub shaft 11 and the other the axis of the aligned hearings in the ends 14 and 15 of the yoke 13.

As will be observed from Figure .1 if the handle 9 is rotated clockwisely the horizontal arm 10 will also rotate in a clockwise direction. It ismanifestly impossible that the arm 10 should rotate initially at its maximum speed, since the speed of rotation necessarily begins at zero and rises to a maximum. At the beginning of rotation, the force of inertia will therefore be greater than the centrifugal force consequently the investment flask 20 and the molten globule will not take up at once'the motion of rotation imparted to it by the arm 10 and the yoke 13 will be displaced angularly. in counter-clockwise direction. Since the same inertia force which controls the position of the investment flask 2O influences the behavior of the globule within said flask said globule will remain within said flask during the initial period of rotation and have no tendency tobe slung therefrom. But the speed of rotation rapidly rises to a maximum and the centrifugal force becomes relatively great causing a. straightening out of the yoke 13 into a position radially of the arm 10 and at the same time causing the inv ment flask 20 to swing outwardly upon its pivotal supports 16 thus maintaining said flask behind the globule of molten material which is also urged to move outwardly by the same force;

When yoke 13 is alined with the arm 10 as shown in Figure 1, the device will operate equally well irrespective of the direction in which the arm 10 is rotated. And the flask must necessarily assume a position in which the molten globule will not be slung abl from the conical depression in the upper end thereof. There is no conditionalspeed of starting, the cup responding as perfectly to a rapid start as to a.slow one.

Should the rotation of the hand crank be abruptly stopped the result would ordinarily be a sudden cessation. of rotation of the arm 10 with a consequent disappearance of the centrifugal force acting upon the investment flask, the result being a slinging out of the molten globure due to its own inertia. This contingency has been adequately provided for in my invention by the construction of the vertical joint formed by the stub shaft 11, and the hollow sleeve 12 carrying the unbalanced yoke 13. Should the rotation of the arm 10 be suddenly arrested the sleeve 12 and yoke 13 will at once begin to rotate, maintaining the centrifugal action of the investment flask until friction gradually brings the parts to a state of repose.

The restriction imposed upon the movements of the investment flask relative to the arm 10, by which it is limited to movement about two axes lying at right angles to each other has a dampening effect upon a great many spurious swinging movements of said flask which would occur through vibration of the casting machine due to the unbalanced mass of the rotating yoke, and to instability of the shelf or bracket upon which the device is supported. This results in a construction which is substantially free from the possibility of accidental slinging'of the metal from the investment flask when the device is rotated, such as would occur if such spurious swinging movements were permitted to have free amplitude.

The advantage of having the arm 10 swing in a horizontal plane permits the entire path of rotation to be above the level of the table or shelf on which the device is mounted and the dependent position of theinvestment flask relative to the rotating parts permits unobstructed access of the blow pipe to the inside 'ofsaid flask.

In the modification shown in Figure 3 the swivel joint at 11 and 12 is done away with and an integral post 2 1 substituted therefor which carries at its upper end an elongated bearing 25 in which a shaft 26 is rotatably mounted; This shaft has at one end the bifurcated'yoke 13 having spaced ends one of which is shown at 16 and from which hangs the swinging ring 19 carrying the investment flask 20 said parts being similar to those designated by like reference numerals in the modification exemplified in Figures 1 and 2. The opposite end of the shaft 26 is counterbalanced by a counterweight 27 the mass of which in this case is preferdistributed on all sides of the shaft 26. n the operation of this modification the inertia of the flask 20 causes a partial rotation of the shaft 26 Within the bearing 25 and centrifugal force urges the flask 20 to swing outwardly in a direction in line with the horizontal arm' 10. \Vhile this modification embodies bined crucible and investment flask mounted to swing around two axes arranged at right angles to one another it lacks the vertical joint by means ofwhich if rotation of the arm 10 is suddenly stopped, the centrifugal force is continued and the molten globule retained within the flask.

A modified form which combines the functions of the devices of Figures 1 and 3 as shown in Figure 8 in which the swivel joint between the stub shaft 11 and the sleeve 12 is present, the yoke 13 being at the same time rotatably carried in a horizontal bearing at the upper end of said sleeve. In this embodiment of this invention the inertia of theinvestment flask causes a slight tilting of the yoke at starting, before said yoke has had time to take up its bodily rotatable movement around the post 11.

The modification shown in Figures l and 5 is similar in its principle of operation to that of Figure 8. In this case, however, the swinging ring 19 has pivotally secured to it at diametrically opposite points at right angles to its axis of rotation another swinging ring 28 the latter being adapted to function as a seat for the flange of the investment flask 20. The function of the ring 28 is to swing in obedience of the inertia of the flask 20 and the ring 19 in response to centrifugal force. ,The position of the investment flask in all three modifications at any time during the period of rotation of the device is the component of the ositions assumed by said investment flask with respect to the two axes arranged in right angles to each other with respect to which it is 'free to swing.

Having described my invention what I claim as new and desire to secure by Letters Patent, is

1. A centrifugal casting machine comprising an arm mounted to rotate in a horizontal plane, means for rotating said arm and an investment flask in operative relation to said arm and limited in its movement to rotation aboutaxes which are perpendicular each to each.-

2. A centrifugal casting machine comprising an arm mounted to rotate in a horizontal plane, means for rotating said arm and an investment flask rotatable with said arm and mounted for movement relative thereto, said relative movement being limited to rotation about two axes arranged at right angles to one another.

3. A centrifugal casting. machine comprising an arm mounted to rotate in a horizontal plane, means for rotating said arm, a yoke, a vertical swivel joint connecting said yoke and said arm, an lnvestment flask,

the broad concept of a coman unbalanced yoke, a vertical swivel jointv connecting said yoke and said arm, an investment flask, a swivel joint connect ng said investment flask and yoke, the axis of said joint lying in a plane perpendicular to the axis of the vertical 's wivel joint.

5. A centrifugal casting machine comprising an arm mounted to rotate in a horizontal plane, means connected to said arm intermediate the ends thereof for rotating said arm, a yoke, a vertical swivel joint connecting said yoke to one end of said arm, a counterbalance weight adjustably secured to the other end of said arm, an investment flask, a swivel joint connecting saidinvestment flask and yoke, the axis of said joint lying in a plane perpendicular to the axis of the vertical swlvel joint. v v 6. A centrifugal casting machine comprising an arm mounted to rotate in a horizontal plane, means for rotating said arm, an unbalanced yoke, a vertical swivel joint connecting said yoke and said arm, an investment flask, a swinging ring for holding said investment flask, means for swivelly supporting said ring upon said yoke, the axis of said supporting means lying in a plane perpendicular to the axis of the vertical swivel joint.

. 7. A centrifugal casting machine comprising an arm mounted to rotate in a hori zontal plane, means for rotating said arm. an unbalanced bifurcated yoke, -avertical swivel joint connecting said yoke and said arm. an investment flask, a swinging ring for holding said investment flask, said ring being provided with upwardly extending arms having off-set ends, means for swivelly supporting said off-set ends in said bifurcated yoke, the axis of said supporting means lying in a plane perpendicular to the axis of the vertical swivel joint.

8. A centrifugal casting machine comprising an arm mounted to rotate in a horizontal plane, means for rotating said arm, anunbalanced bifurcated yoke, a vertical swivel joint connecting said yoke and said arm, an investment flask, a swinging ring for holding said investment flask-provided with upwardly extending arms having olfset ends, means for swivelly supporting said off-set ends'within said bifurcated yoke, the axis of said supporting means lying in a plane perpendicular to the axis of the vertical swivel joint, said investment flask being insertable through said ring and provided with a with said. ring.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

JOSEPH V. TURNER. lVitnesses FRANK W. BENTON, THEODORE H. FRIES.

peripheral flange engagea-ble:

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