US2675414A - Induction furnace - Google Patents

Description

2 Sheets-Sheet l INVENTOR. [mil 1? la a'fa/ HTI'OPNEY E. R. CAPITA INDUCTION FURNACE April 13, 1954 Filed Dec. 20, 1951 April 13, 1954 E. R. CAPITA INDUCTION FURNACE Filed Dec. 20, 1951 2 Sheets-Sheet 2 7s vi a9 2.174 75 71 i1 9 l 55 a as 12 60 61 103 ,0 100 5g 89 as 8 a7 w 91 101 u a2 72 M as l I is as v a 25 I i v 1 v mmvrox. 30 Emil 1?. la n'fa 51 F BY 4 7' TORNE Y Patented Apr. 13, 1954 UNITED STATES PATENT OFFICE INDUCTION FURNACE Emil R. Capita, North Bergen, NJ.

' Application December 20, 1951, Serial No. 262,579

21 Claims.

The present invention relates generally to vacuum heating furnaces of'the electric induction type and moreparticularly'to an improved vacuum furnace which embodies a stationary casing or shell containing 'a tiltable induction heating coil and crucible.

Induction heating furnaces for melting and pouring metals in vacuum, or in some particular gas atmosphere, are generally known but previous types have been objectionablefor various reasons. Some of themhave required opening the vacuum casing afterthe metal i molteirin order to pour the molten metal from a crucible into a mold; this is highly objectionable and largely negates advantagesgained by melting the metal in a vacuum or some desirable gas atmosphere for the reason that during pouring the molten metal is exposed and picks up oxygen and other gases in the atmosphere. In order to'avo'id this objection entire furnace casings together with their contained heating'coils and crucibles have been mounted on trunnions, sothat the whole structure could be tilted to pourmolten metal from a crucible into a mold contained in a portion of the casing and 'tilt'able therewith.

Tilting the whole furnace structure is objectionable in many instances as it is cumbersome, generally requires the use of a drive motor and gearing for tilting the entire furnace structure, and requires the use of excessivelylong electric conducting cable and water hoses to allow for movement of the furnace between melting and pouring positions.

The present invention aims to overcome or minimize the above and other difliculties by providing a new and improved vacuum heating furnace which utilizes a stationary vacuum casing containing a tiltable crucible and an induction heating coil, tilting of the coil and crucible be ing readily achieved from the exterior of the casing through means which conducts electricity and cooling fluid to and from the coil'butwhich prevents passage of gases from the atmosphere into the casing.

An object of the present invention i to provide a new and improved vacuum type induction heating furnace.

Another object of the'invention is to provide an improved vacuum heating'furnace which embodies a stationary casing containing a tiltable heating coil.

Another object ofth inventionis to provide improved means for conducting electricity and cooling fluid to ahdfr'orn a heating coil'butwhich is adapted to 'preventpassage of gases'int a vacuum furnace.

Still another object of the invention is to provide an improved vacu'umtype induction heating furnace of relatively simple and inexpensive construction.

Other and further objects of the invention will be obviou upon an understanding of the illustrative embodiment about tobe described'orwill be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the artupon 'employmentbf the invention in practice.

A preferred embodiment of the inventiori has been chosen for purposes of illustration and description and is shown in theaccompanying drawings, forming a part of the specification, wherein:

Fig. 1 is a perspectiveview"showing apreferred embodiment of the present invention;

Fig. 2 is a horizontal sectional view looking down into the furnace illustrated in Fig.1;

Fig. 3 is a fragmentary sectional view illustrating the "general relationship of the induction heating coil, crucible and pouring mold of the present invention;

Fig. 4*is a longitudinal sectional view showing the means for conducting electricity and cooling fluid to'and from the-heating coilwithm'eans for tilting the combined assembly;

Fig. 5 is a sectional view taken along line 5 5 of Fig. 4; I

Fig. 6-is a sectional view taken' along line 6---6 of Fig. 4; and V v 'Fig. '7 is a sectional view taken along line 1"I of Fig. 4.

As shown in Figs. -'13,- the present vacuum heating furnace comprises a casing or s'hell 2, stationarily mounted on supporting leg 3. The casing may be built up "b welding together suitable sections of non-magnetic steel. When charged and -re'ady for use acover member 4' may be placed 'over an open upper end "ofthe' casing 2 and clamped down againstan intermediate gasket (not shown) by retaining dogs or latches 5 located at spaced intervals around the circumference 'of'the casing. An opening-at one side of thecasing 2 mayc'ommunicate with a conduit 1 for exhaustingair' fromthe casing, the air being withdrawn bya suitable vacuum pump (notshown). 'Windows'iii of heat resistant glass may be provided at suitable locations on the casing 2 or cover 4 for viewing the interior of'the furnace. Any suitable pyro'meter or other temperature indicating means may be provided for giving the temperatureofimetalor any portion at the-interior of'the furnace. ".Water "cooling pipes ll may beattached toandextend along appropriate portions of the casing 2 and cover 4 for the purpose of keeping the cover or casing from becoming overheated.

Within the casing 2 and supported on a suitable rotatable or tiltable framework I 6 are the crucible IT and its encircling induction heating coil I8. The heating coil I8 is preferably of copper tubing wound in the form of a coil so that a crucible placed within the confines of the coil may be subjected to a high frequency electromagnetic field created by current flowing through the heater oil. Cooling water flows through the coil tubing to prevent overheating thereof. As shown in Fig. 8 any one of a plurality of molds may be moved into alignment with a spout 2I of the crucible by rotating exterior hand wheel 22 so as to operate suitable shafting and gearing connected with the means which supports the molds 20.

The means I6 which supports the crucible I1 and coil I8 is rotatable about an axis which extends through a supporting shaft 23 and bearing 24 (right side of Fig. 2) and supporting and rotating means 25 (left side of Fig. 2). The latter means prevents passage of gases into the casing 2 and yet provides flow of electricity and cooling fluid to and from the induction coil I8 through the casing wall.

Handles 28 connect with the supporting and rotating means 25 at the exterior of the casing 2 to provide for tilting the induction coil I8 and crucible IT, as will be described in detail hereinafter. Current conducting cables 30, 3| and hoses 32, 33 are provided for conducting electricity and cooling fluid, usually water, from a supply connection 35 to the coil I8 and from the coil I8 to a discharge connection 36. Electric current may be furnished to the cables 30, 3| by any suitable generator (not shown) The supporting and rotating means 25 which conducts current and water to and from the coil and serves to tilt the coil while retaining a vacuum-type seal with the casing wall, is shown in detail in Figs. 4-7 and will now be described. In the longitudinal sectional view of Fig. 4 the easing wall 2 is shown provided with an opening 38 through which extends a hollow member 39 of stainless steel. This member is tubular and is preferably attached by welding 48 to the casing wall 2 to form a fixed support through which extends a rotatable bronze tube or member 42, this member in turn carrying tubular copper members for conducting current and cooling fluid.

The rotatable tubular member 42 has an annular enlargement 43 adjacent its inner end which abuts against the end of the fixedly positioned hollow member 39, so that endwise movement of the tubular member in one direction is prevented. While the rotatable member 42 is preferably of bronze, it will be understood that any other suitable material may be utilized. Leakage of air between the fixed supporting member 39 and the rotatable tubular member 42 is prevented by a gasket 45 of neoprene or other suitable material. This gasket may be compressed, so as to form a tight seal between the fixed member 38 and rotatable member 42, by a gland member 41 which is pulled toward the fixed member 39 by bolts and nuts 50.

The inner end of the rotatable tubular member 42 preferably has attached thereto, by bolts 53, a portion 5| of the framework It which supports the coil and crucible. When rotatable member 42 is turned in the fixed supporting member 39 the crucible and coil turn with the outer tubular members 68 and M.

4 framework I6. To facilitate such rotation an outer portion of the rotatable member 42 has attached thereto the tilting handles 28 which pro- Ject from collar portions 55, the collars being firmly clamped against the rotatable member 42 by bolts and nuts 56.

Electric current and water are delivered to the inlet end 58 of the coil I8 by concentric or coaxial copper tubes 68, 6|, current flowing through the copper tubes to a copper end cap 62, thence along a copper pipe 63 to the inlet end 58 of the induction coil I8. Cooling water reache the inlet end 58 of the induction coil by passing through the space between the two concentric copper tubes 80 and BI. These two copper tubes are shown spaced from each other at their inner ends by securing them in spaced relationship to the copper end cap 62; at their outer ends the two copper tubes are held spaced from each other by an annular ring 65 of copper or other conducting material. Electric current may be delivered to the copper tubes by an inlet connection BIS which connects with the inlet cable 38 through apertured means 61. The rubber inlet hose 32 surrounds the inlet cable 38 and coolin water may pass through the hose 32, apertured means 61, terminal 86, opening 68 into the space between the two copper tubular members 68, 6 I.

The conducting tubes 68, 6| are separated from the rotatable tubular member 42 by generally tubular insulating members I I, I2 of Bakelite, teflon or other suitable material. A gas-tight seal is provided between the outermost conducting member 68 and the rotatable member 42 by a neoprene or other gasket I3, the annular insulating member I2 being movable inwardly by a retaining ring 14 and bolts I5 so as to compress the neoprene gasket 13 against one end of the tubular insulator II. The innermost end of insulating member II is held against longitudinal movement as it abuts against an outwardly facing surface of the portion 5| which provides an attachment for the crucible supportin framework I6.

Each of the insulating members II and I2 preferably has a relatively long recess or cut-away portion at its inner annular surface. This provides a greatly increased slide spark distance and thereby minimizes passage of current from the copper tube to adjacent portions of the rotatable member 42.

Current and cooling water which pass through the induction heating coil I8 are conducted away from an outlet end 59 thereof through a copper pipe I8 shown disposed centrally of and extending through the two outer copper tubes 60' and 6 I. Current flows along this central copper pipe I8, through copper end terminal 80 to outlet cable 3|. Cooling water passes through the interior of central pipe I8, through apertures 8| of retaining means 82, through the interior end terminal 88, through apertures 84 in the end terminal, and thence out through the rubber hose 33.

The central copper pipe I8 is insulated from the inner copper tube BI by generally tubular members 81, 88 of Bakelite, tefion or other nonconducting material. Here again a gas-proof joint is preferably provided by a neoprene gasket 89 which fills the annular space between the exterior of the copper pipe 18 and the interior of the copper tube BI. The gasket 89 may be compressed by a clamping ring 9| and bolts 92 which thread into suitable apertures in the annular copper ring secured to the inner and Insulating member 81 is prevented from moving longitudisaws-ma nally, under therinfluenceifofrzpressure applied against the me'oprene gasket 289'; by 'airetaining ring 94 soldered :or otherwisetsecuredito'therexterior ofthe copper pipe-18. The tnsulator' members 8.1 and88 'which encircleithe :central copper pipe 78 arepreferably provided withrelatively deep recesses or'cut-away portions rattheir exteriors to provide increased slide sparkdistan'ces such as those previously referred to in "connectionwith the insulators? l, 12.

The inlet terminal which delivers current and cooling fluid to the two outer tubularamembersmay'include' semi-circular portionsfi-Ql, '98, clamped against the exterior "of the'coppertu'be 60 by nuts and bolts 99. 'The hollow outlet terminal =80 has a conical surfaced!!!) whichmay be pulled tightly against an end 'of'ithe central copper pipe 18'by a bolt l III which extends therethrough and threads into an opening in the retaining means 82. A spark'plug type gasket 103 may be used to form a'tight seal between the terminal 80 and the head of the bolt'ifil, to thereby prevent leakage of fluid along'the bolt.

While the current'and cooling fluid have been described as entering through'the "terminal 66 and emerging-through the terminals 89, it will be understood that "the direction could be reversed so as to have current and fluid enter through the terminal 80 and emerge through the terminal 66.

When current has been flowing through the induction heating coil l8 for a sufficient time, metal contained in the crucible i 6 will be molten. At this time the handles 28 may be moved so as to turn the rotatable member 42, supporting framework l6, coil I3 and crucible H. Molten metal'flows out the spout 2| into a mold 2!; aligned therewith. The copper tubes 65 and 6!, central copper pipe "18 and various insulators may turn with the rotatable member 42. though 'the'interior of the casing 2 may be subjected to high vacuum no airorother gas enters the casing along any of the joints between the various tubes, insulators or pipes of the present coaxial conductor as the various gasket tightly seal the joints against this, The coaxial conductor may be readily tilted by the handle 28. Only a slight amount ofslack need beprovided in the electric cables and hoses as the crucible may be emptied by turning it through arelatively short distance. Preferably exposed portions of the coaxial conductor, namely the'termina-ls 66. 8B and other adjacent portions are covered by a protective cap 195. Valves I05 may be provided for admitting air to the casing 2 after metal has solidified in the molds 20.

It will be seentha-t the present invention provides a new and improved induction heating type of vacuum furnace which does not require'rotating the entire furnace in order-to pom .molten metal into a mold. The furnace casing or shell may be stationarily mounted and only the crucibio and heatingcoil :need rotate at'the interior of the casing. No auxiliary power motor is requiredrto tilt the crucibleas thigmay be readily achieved by'app'lying leverage to suitable laterallypro'jecting'handlesatthe exterior of the easing, the handles "connectingwith a rotatable portion of the present new coaxial conductor. Current and cooling fluid readily pass through the coaxial conductor'but passage of air along any jointsbetween relatively. movable partsis .prevented.

As various changes may be made in the form, construction and arrangement of the parts here- 6 in-without departing: from the :spirit and 'lSCOIJB of the inventiomand"withoutsacrificing :any of its. advantages, :it :iszto zberunderstood :that all matterrherein-ris to beinterpreted as illustrative and not in a limiting sense.

'What I'-' claim' is:

' 1. A 'd'evice' ofthe classdescribed"comprising the combination of a normally stationary "casing, an induction heating coilrxin saidicasing, means for tilting said icoil 'with'respect :to the casing including a rotatable member extending through a wall of the casingghollow electric conducting means connected" with saidc'oil and extending through-saidrcasing wall for conducting current and cooling-fluid tozand from the heating coil, and leakproofmeans for'tiltably mounting said conductingmeangwith respect to the casing wall.

2. A device as claimediin'claim 1,:in' which said rotatable member is hollow, said conducting means extends therethrough, andsealing means are located adjacent 1 the ends of isaid rota-table member and saidconducting means for providing a fluid passage through said rotatablehollow member between itiandsaid conducting means.

3. A device as claimed'in claim 2, in'which a crucible supporting platform is connected tosaid rotatablemeniber for rotation therewith.

4. In 'a device o'fthe .classz described, the combinationof acasing wall, ahollow member extending throughz'saidwall; aplurality of electric conducting'membersrextending through said hollow xmember, sealing: means intermediate said hollow member and one rof rsaid conductinginembers for :minimizingflp'assage "of I fluid therebetween, at IGaStIOHG'SOf said rconducting members being rotatable with resp'ect'it'o said hollow member and aninduction'x'heating coil-having terminals in communication with-said conducting members within saidrcasingfwall.

5. A deviceias claimed inclaim .4,'in which said hollow member has :an elongated: tubular bearing surface at its interior 'iorisupporting said conducting members. and a'crucible' supporting platform for a-rcruci'bleadapted to'seat'in said coil.

6. In a device ofthe class described, the co: bination of a'tca'sing wall, a hollow'supporting member 'extending' through androtatable with respect to saidwalha' first. hollow electric conducting member extendingfthrough' said supporting member, a secondelectric conducting member extending through said. first hollow conducting member, means intermediate said supporting member and said first rholl'owconducting member for minimizing passage of fluid therebetween, said conducting members being rotatable with respect to 'saidsupporting member, said first hollow conducting member being in communication with a terminal'ofan .induction heating coil. and said second electric conducting member being in communication: with another terminal of 'saidxinduction heating coil.

'7. A device as claimed'inclaim' 6,'in which of said conductingimembers is hollow and each is separated from the other by insulatingxmeans.

' 8. A device as claimed in claim '7, in which said insulating means is recessed adjacent end portions thereof toprovide increased slide snarl: distance.

'9. A device of the class described comprising the combination of a hollow member adapted to be secured to a casing wall and extend through an opening therein, electric conducting means comprising apair of radially spaced hollow concentric conduits extendingthrough said hollow member, additional electric conducting means comprising a hollow electric conducting conduit extending through the first conducting means, insulating means intermediate said hollow member and first conducting means and intermediate the first conducting means and said additional conducting means, and means rotatably mounting said hollow member in said casing wall, whereby said conduits are adapted to communicate with an induction coil.

10. A device as claimed in claim 9, in which there is provided a heating coil of pipe having spaced portions electrically connected to and in fluid communication with the first conducting means and the additional conducting means whereby cooling fluid may flow into the pipe through one of said conducting means and out of the pipe through the other conducting means.

11. A device as claimed in claim 10, in which means is connected with said first conducting means adapted to conduct current thereto cooling fluid to the space between said concentric conduits, and in which means is connected with said additional conducting means adapted to conduct current therefrom and cooling fluid from the hollow conduit thereof.

12. A device as claimed in claim 10, in which means comprising an electric cable surrounded by a hose is connected with said first conducting means adapted to conduct current thereto and cooling fluid to the space between said concentric conduits, and in which means comprising an electric cable surrounded by a hose is connected with said additional conducting means adapted to conduct current therefrom and cooling fluid from the hollow conduit thereof.

13. A device as claimed in claim 9, in which there is provided a rotatable member between said hollow member and the first conducting means, and an operating handle extends laterally from said rotatable member for rotating it.

14. A device of the class described comprising the combination of a normally stationary easing, a hollow member secured to a wall of said casing at an opening therein, electric conducting means comprising a pair of spaced hollow concentric conduits extending through said hollow member, additional electric conducting means comprising a hollow electric conducting conduit extending through the first conducting means, insulating means intermediate and separating said hollow member and first conducting means and intermediate and separating the first conducting means and said additional conducting means, an induction heating coil of pipe in said casing having spaced portions connected to and in fluid communication with the first conducting means and the additional conducting means, and means for tilting said coil from the exterior of said casing with respect to said casing, including means rotatably mounting said hollow member in said casing wall and means provided on said rotatable member in co-operative relation to said coil, said casing being adapted to be placed under a vacuum.

15. A device of the class described having a casing with an opening therein, a hollow member extending through said opening, an induction heating coil, a hollow electric conducting conduit extending through said hollow member into communication with said coil, an additional hollow electric conducting conduit extending through the first conduit also into communication with said coil, insulating means intermediate said hollow member and said first conduit and intermediate the first conduit and said additional conduit,

sealing means at the extremities of and intermediate said hollow member and said first conduit providing a passage for fluid, a first port for said passage communicating with an electric and fluid current source, and a second port for said passage communicating with a terminal of said coil and located on a side of said casing wall opposite that of said first port, said additional hollow electric conducting conduit communicating with another terminal of said coil and having a port communicating with an electric and fluid source.

16. A device as claimed in claim 15 in which means are provided rotatably mounting said hollow member with respect to said casing wall.

17. A device as claimed in claim 16 in which means are provided rotatably mounting said hollow member with respect to at least one of said conducting members.

18. A device as claimed in claim 15 in which means are provided rotatably mounting said hol- 10w member with respect to said casing Wall, and a crucible supporting platform is provided on said hollow member adapted to tilt said coil upon rotation of said hollow member.

19. A device as claimed in claim 18 in which means are provided rotatably mounting said hollow member with respect to at least one of said conducting members.

20. A device as claimed in claim 18 in which means are provided rotatably mounting said hollow member with respect to said first conduit, and means are provided rotatably mounting said first conduit with respect to said additional holiow electric conducting conduit.

21. In a device of the class described, the combination of a casing having a wall with an opening therein, a hollow member mounted in said wall at said opening, first electric conducting means extending through said hollow member, additional electric conducting means extending through said first conducting means, insulating means intermediate and separating said hollow member and first conducting means and intermediate and separating said first conducting and said additional conducting means, an induction heating coil in said casing having portions connected to and in fiuid communication with said first conducting means and said additional conducting means, means for tilting said coil from the exterior of said casing with respect to said casing including means rotatably mounting said hollow member in said casing wall, and means provided on said rotatable member in co-operative relation to said coil, said casing being adapted to be subjected to a partial vacuum whereby said coil may be tilted within said casing in said partial vacuum and cooling fluid may be delivered thereto through the intermediation of said conducting means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,295,309 Harbeck et al Feb. 25, 1919 2,289,434 Coley July 14, 1942 2,504,840 Johnson Apr. 13, 1950 2,538,603 Thys Jan. 16, 1951 2,551,341 Scheer et al. May 1, 1951 FOREIGN PATENTS Number Country Date 439,472 Great Britain Dec. 6, 1935

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