US2004457A - Casting apparatus - Google Patents

Description

June11, 1935. E BERINGER 2,004,457

CASTING APPARATUS Filed Aug. 15; 1952 I 2 Sheets-Sheet 1 I710 Berz'rgaez;

I N V EN TOR.

A TTORNE Y.

June 11, 1935; E. BERINGER 2,004,457

CASTING APPARATUS 7 Filed Aug. 15, 1932 2 Sheets-Sheet 2 Z7150 fierz'lyw;

INVENTOR.

A TTORN E Y.

Patented June 11, 1935 UNITED STATES PATENT orrice V i lfiiifii Application some 15, 1932, No. 28,903 2 Claims. (or 2245.1)

This invention relates to certain new and useful improvements in casting apparatus of the type primarily designed for use in making dental and like castings.

More particularly, the present invention has reference to an improved apparatus for use in connection with centrifugal casting machines, including an improved electrically heated oven, quick detachable means for connecting the heating element or resistance of the oven with a source of electrical energy, and means for controlling the amount of electrical energy supplied to said heating element or resistance, whereby the user of the apparatus may at all times have ready control over the heat of the oven and exact knowledge of the latter for insuring the production of castings which are uniformly sound, homogeneous, free from blow holes, and possessed of fine, sharply defined feather edges, where such exist in the original pattern.

Heretofore, the flasks of centrifugal casting machines have usually been heated by means of separate ovens, burners, etc., to an approximately suitable temperature, and in removing the flasks from any of these heating appliances and placing them on a cold casting machine, and then consuming the necessary time to melt the metal in the crucible operatively associated with the flasks on the casting machine, such flasks become variously chilled so that their temperature is not known and often unsuitable, thereby resulting in the production of castings which are often inferior. It is thus evident that with these known casting devices the uniform production of superior castings is quite diflicult and requires the exercise of extreme skill and care. The primary object of the present invention, therefore, is to provide an apparatus by means of which the oven may be readily heated to a known and desired temperature until such time as the metal has been melted for transfer to the flask positioned in the oven and while the oven is operatively associated with the casting machine, and to provide means whereby the heating element or resistance of the oven may be quickly disconnected from the source of electrical energy.so that the casting machine may be promptly operated for eiiicient transfer of the metal from the crucible to the flask before the mold has chilled excessively. In this way the uniform production of superior castings may be readily and easily accomplished without the exercise of extreme care or special skill. 'A more specific object of the present invention is to provide an electrically heated oven for centrlfugal casting machines which is extremely simple and durable in construction and efllcient in operation.

A still further object is to provide a casting apparatus including an oven and manually con,- 5 trolled means for electrically heating the same, whereby the oven may be effectively employed also as a wax eliminator and plaster expander.

Other objects and features of the invention will become apparent from the following descrip- 10 tion when considered in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of a casting apparatus embodying the present invention operatively associated with a centrifugal casting ma-, 15 chine.-

Figure 2 is an enlarged fragmentary view showing part of the apparatus of Figure 1 in top plan, the oven being partly broken away and in section.

Figure 3 is a vertical section of the construction shown in Figure 2, the line or section being centrally and longitudinally of the oven and crucible.

Figure 4 is a view of the oven detached from the casting machine, partly in end elevation, and 5 partly broken away and in section; and

Figure 5 is a transverse section through the oven on the plane indicated by the line 5-5 in Figure 3.

Referring in detail to the drawings, the present 30 invention is shown in conjunction with a conventional form of centrifugal casting machine embodying a frame 5 adapted to be secured upon a table or other support 6 and having a vertical top hearing I in which is journaled a shaft 8 35 having secured on its lower end a pinion 9 meshing with a driving gear It provided with an operating handle I l and joumaled on a horizontal spindle l2 carried by the frame 5. Mounted upon the upper end of the shaft 8 is a horizontal oven 40 supporting bar I3 having a counterweight l4 longitudinally adjustable on one end thereof and carrying an oven holder at the other end consisting of an inner plate ll fixed to the bar I3 and having a central opening it through which the 45 metal is transferred to the flask. The oven holder further includes an outer plate l'l arranged in spaced parallel relation to the inner plate l5 and rigidly connected to the latter by means of rods I 8, and a clamping screw l9 having screw threaded 50 engagement with the outer plate I! and carrying at its inner end a clamping plate 20- for engagement with the outer end of the oven. In this way the casting flask is eiiectively clamped in proper P sition within the holder and with relation to a 55 crucible 2| supported in a bracket 22 provided at the inner side of the inner plate I! and upon the adjacent end of the supporting bar l3.

As previously stated, the present invention relates to improved apparatus for use in connection with a centrifugal casting machin and including an electrically heated casting and wax elimination oven. As shown, this oven includes a cup-shaped core 23 of suitable insulating material, such as Denver flre clay baked to a very hard condition, and having a central recess or cavity open at one end for registration with the opening it of the oven holder and of a size to snugly receive the flask having the usual plaster mold 24 arranged therein and consisting of an open ended cylindrical shell 25. The mold 24 has the usual matrix 26 and central inlet opening 21. As is well known, the matrix is made by any usual method, such as by casting the plaster around a form of wax, andthen heating the mold so as to dissolve or eliminate the wax and leave the matrix of the desired shape. Formed in the side wall of the core 23 entirely about itsrecess or cavity is a series of uniformly spaced longitudinal passages which are alternately connected at opposite ends of the core to form a tortuous passage in which is arranged a suitable helically formed heating element or resistance 29 having adjacent ends terminating in adjacent ones of the passages 28 at one side of the mold and respectively connected to diflerent onescf a pair'of electrical contact pins 30 projecting laterally from such side of the oven for engagement by the socket member of a two-part quick detachable electrical connector. It will thus be seen that the heating element or resistance includes major relatively long portions extending in the passages 28 longitudinally of the core 23 so as to evenly distribute the heat around the oven. The oven further includes a casing 3| of thin metal having a lining of asbestos or other heat insulatingmaterial as at 32, and in which the core 23 is snugly fitted. The casing further includes an annular retaining ring overlying the wall of the core 23 at its open end and detachably secured in place as at 34 to removably secure the core within the casing. The retaining ring 33 has a relatively large central opening registered with the flared entrance opening of the mold 24 and through which the metal passes from the crucible 2| into the matrix 26. The retaining ring 33 can be readily removed to facilitate removal of the core 23 so that the resistance element and the core may be readily renewed or repaired. As shown, the contact pins 30 are carried by binding posts 35 clamped in suitable openings provided in the side of the casing 3| and to which the ends of the heating element or resistance 29 are connected as clearly illustrated in Figure 4. I

The present invention also contemplates the provision of means for delivering electrical energy to the resistance 29 by way of contact pins 38 and means for .manually controlling the amount of electrical energy supplied to said heating element or resistance 29. As shown, these means consist of an attachment cord 36 having at one end the male member 31 of a two-part electrical connector adapted to be readily plugged into an outlet receptacle of a house wiring sys tem so as to derive the electrical energy therefrom, and having at the other end a female member 38 of a. two-part quick detachable connector which may be readily plugged into engagement with the contact pins 38 or disconnected therei'rom. Interposed in the attachment cord 36 5 a suitable rheostat 39 by means of which the amount of electrical energy supplied to the element 29 through the attachment cord 36 may be controlled. In this way a graduated heat may be furnished to the oven so that exact knowledge of the temperature of the same may be known at all times. Obviously, the construction described permits heating of the oven when in operative position relative to the casting machine as shown in Figure 1 and while the metal to be casted is being melted in the crucible 2|. Also, as soon as the oven is properly heated and the metal is melted in the crucible 2|, the connector member 38 may be instantly disengaged from the'contact' pins 3|! to permit prompt rotation of the bar I3 and completion of the casting operation without incurring an intervening period during which the mold might become unduly chilled.

In operation, assuming that the flask has been prepared in the usual way and the wax pattern has been inserted therein, this flask is then inserted in the core 23 of the oven. The connector member 38 is then engaged with pins 38, the con nector member 31 is engaged in an outlet receptacle, and the control lever of the rheostat 39 is operated to supply the desired amount of electrical energy to the resistance 29 for dissolving and thoroughly evaporating the wax in the flask. The oven is then placed in operative relation to the crucible 2| as shown in Figures 1.to 3 inclusive, and the controlling lever of the rheostat 39 is further moved/to increase the supply of electrical energy and thereby properly heat the mold in the oven for the casting operation. While the mold is being heated, the metal to be cast is suitably melted in the crucible; whereupon the connector member 38 is disengaged from pins 38 and supporting bar I3 is promptly rotated by operation of handle The casting operation can then be properly effected and completed without allowing the mold to become unduly chilled before transfer of the molten metal from the crucible to the matrix 26. By the use of the present apparatus, therefore, uniform superior castings may be readily produced without the requirement of special skill or the exercise of extreme care.

While I have shown one specific embodiment of my invention, it is to be understood that minor changes may be made without departing from the spirit and scope of the invention as claimed.

What I claim as new is:

1. A centrifugal casting machine comprising a rotatable shaft, a cross bar carried by and rotatable with said shaft, a crucible holder mounted on one end of said bar, an adjustable oven clamp carried by the last-named end of said bar at the outer side of said crucible holder and including an inner clamping plate fixed to said bar and having a central opening through which metal may be transferred to a flask in the oven from a crucible in said crucible holder, said oven clamp further including an adjustable outer clamping plate and means to adjust said outer clamping plate toward the inner clamping plate, an oven removably mounted in said oven clamp, said oven being of cup-shape and open at its inner side for removable reception of a flask, and means including an electrical heating resistance forming part of said oven for heating the latter to any desired predetermined temperature while mounted in said clanip.

2 A centrifugal casting machine comprising a rotatable shaft, a cross bar carried by and rotatable with said shaft, a crucible holder mounted On one end of said bar, an adjustable oven clamp carried by the last-named end of said bar at the outer'side of said crucible holder andincluding an inner clamping plate fixed to said bar and having a central opening through which metal may be transferred to a flask in the oven from a crucible in said crucible holder, said oven clamp further including an adjustable outer clamping plate and means to adjust said outer clamping plate toward the inner clamping plate, 'an oven removably mounted in said oven clamp, said oven being of cup-shape and open at its inner side for removable reception of a flask, means including an electrical heating resistance forming part 0! said oven for heating the latter to any desired predetermined temperature while mounted in said clamp, said oven clamp further including an outer stationary plate and rods rigidly connecting the latter with the inner clamping plate, and a clamping screw having screw-threaded engagement with said stationary outer plate and carryin: said outer adjustable clamping plate at its inner end. a I

ERIC BERINGER.

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