US3404874A

US3404874A - Vacuum furnace

Info

Publication number: US3404874A
Application number: US399226A
Authority: US
Inventors: Peter J Wynne
Original assignee: LECTROMEIT CORP
Current assignee: LECTROMEIT Corp
Priority date: 1964-09-25
Filing date: 1964-09-25
Publication date: 1968-10-08
Anticipated expiration: 1985-10-08
Also published as: NL6508770A; BE664758A; GB1087013A; FR1433259A; DE1248308B

Description

Oct. 8, 1968 P. J. WYNNE 3,404,874

VACUUM FURNACE Filed Sept. 25, 1964 s Sheets- Sheet 1 I HEATING I COOLING ZONE INITIAL HEATING 2 ZONE ,3

INVENTOR Peer J 5607276 ATTORNEY Oct. 8, 1968 J. WYNNE 3,404,874

VACUUM FURNACE Filed Sept. 25, 1964 a Sheets-Sheet 2 p 84- 84- //2 E E/I7 INVENTOR Peter Zg/nr ze Y ATTORNEY Oct. 8, 1968 Filed Sept. 25, 1964 53 5g j 52 y P. J. WYNNE VACUUM FURNACE 5 Sheets-Sheet 3 INVENTOR Peter J @7722? BY AT TORNEY United States PatentOffice 3,404,874 VACUUM FURNACE Peter J. Wynne, Pittsburgh, Pa., assignor, by mesne as signments, to Lectromelt Corporation, Pittsburgh, Pa.; a corporation of Delaware Filed Sept. 25, 1964, Ser. No. 399,226

12 Claims. (Cl. 266-3) ABSTRACT OF THE DISCLOSURE A device for treatment of continuous strip material in a'vacuum wherein radiant heat sources transfer heat directly from a source to the material without the deleteri ous effects of glow discharge and the device need not be maintained at an elevated temperature between operations.

This invention relates to vacuum furnaces and, more particularly, to vacuum furnaces which are particularly but not exclusively applicable to the continuous annealing of reactive strip material, such as titanium.

Furnaces for the annealing of strip material have generally involved resistance or gas-fired type heating systems, wherein the entire furnace had to be heated to operating temperatures. For this reason, expensive refractory linings were required. In addition, because of the long period of time required to sufficiently heat such furnaces from ambient temperatures, it was necessary that these furnaces be continuously held at or near their operating Patented o r. s, 1968 uum strip annealing furnace according to the instant iriE' vention is shown to include a roll housing .10. which allows vacuum tightnessto be maintained while the strip mateirial 'is passing continuously into and out of the furiliace, a main vacuum chamber 11 and a furnace cham- The roll housing includes an elongate, horizontally disposed metallic tank or housing 14 'whichencloses a plurality of sets of cylindrical rolls 15 for engatging the strip material 17 as it enters and leaves the furnace. The rolls 15 arearranged ingroups of three, with the rolls in each group disposed in parallel vertical alignment and extending transversely of the cylindrical housing 14. The groups of rolls 15 are disposed in horizontal spaced re.- lation along the cylindrical housing 14 with the upper and central rolls 15 in each group engaging the incoming material to be annealed, while the central and lower rolls engage the outgoing annealed material. A plurality of ellipitical ducts 18 extend transversely of the housing 14 and between adjacent groups of rolls 15 and each has a pair ofopposed slots 20 to permit the, material 17 to temperatures. Where such furnaces were employed to anneal reactive material, it was also required that a separate vacuum chamber be located within the furnace.

It is an object of the invention to provide a vacuum furnace for annealing reactive material wherein the fur. nace need not be held at elevated temperatures between operations.

Another object of the invention is to provide a vacuum furnace wherein heat energy is transferred directly from the heat source to the material being treated without the necessity of heating the furnace itself.

Yet another object of the invention is to provide a metal treating vacuum furnace wherein the heat sources may be operated under a vacuum so that a separate vac: uum chamber is not required.

A still further object of the invention is to provide a metal treating furnace wherein electrically energized infra-red heating means directly heats the material being treated.

Still another object of the invention is to provide a vacuum heat treating furnace employing quartz infra-red lamps. Yet another object of the invention is to providerefiector means for said lamps.

These and other objects and advantages of the instant; invention will become more apparent from the detailed description thereof taken with the accompanying drawings wherein:

FIG. 1 is a side elevational view, partly in section, which schematically illustrates a heat treating furnace according to the instant invention;

FIG. 2 is a top plan view, partly in section, of the fur-" nace illustrated in FIG. 1. g

FIG. 3 is a view taken along lines 33 of FIG. 1; FIG. 4 is a view taken along lines 4-4 of FIG. 3;

FIG. 5 is a section view of a lamp end-portion and the:

pass therethrough. The ducts 18 alternately extend through the opposite sides of the housing 14 for. connection to a vacuum system (not shown).

The main vacuum chamber 11 is a generally cylindrical metallic tank 22 which is disposed coaxially with the cylindrical roll housing 10 and has anopening 23 in one end thereof for sealing engagement .with the open end of the roll housing tank 14. A pair of vacuum ports, 24 open into one side of the tank 22 and adjacent its opposite sides for connection to a vacuum system (not shown);

The furnace chamber 12 consists of an elongate, cylindrical, hollow metallic tank 25, which extends vertically upward from the main vacuum chamber tank .22 and is open at its lower end for connection to an opening29in the top of said tank 22. A suitable metallic cover 26 is tion: outwardlyof the roll housing 10.

affixed in sealing relation to the upper end of the furnace tank 25. v 1

After entering the main vacuum chamber tank- 22, the material 17 passesunder an entrance roller 27, disposed below the opening 29, for redirection up into thefurnace. chamber tank 25. A second roller 28 is disposed adjacent the upper end of the furnace chamber .tank 25 for-re: directing the material 17 downwardly where it passes underan exit ro11erL30 adjacent the roller 27 for redirec- -.The furnace chamber 12 is divided into threeezones, an initial heating zone, a heating zone and a cooling zone; The initial. heating zone is provided at .the lowenendof the tank25 above the entrance roller 27v to bring the ma-. terial: 17 substantially ,up to operating temperatures, theheatingzone is provided ;to. increase the. temperature attained in the initialzone and/or to maintain the material at the desired temperature as it passes through the furnace and the cooling zone is. provided to lower the temperature of the material 17 prior .-to its contact/with the exit roll 30.; v

mounting therefore taken horizontally along the axis of the lamp -1 FIG. 6 is a view taken along lines 6-6 of FIG, 5; and FIG. 7 is a fragmentary view of an alternate embodiment of the instant invention.

. Referring to FIGS. 1 and 2 in greater detail, the vac-.

wHeat energy is supplied'to the-:material 17 by aplurality of infra-red heaters 32 which. extend transversely across the "furnace chamber 25. As seen in FIGS. 3 and 4, each-of the infra-red heaters'32 consists-ofan elongate infra-red quartz lamp '33rand a refiector.34.vAccording' to the preferred embodiment-of. the invention, the reflector 34 is of polished-aluminum and has a-parab'oliccon-' figuration, the lamp 33 being disposed at thew-focus of theparabolang. e

,aIn'the initial heating. zone, the heaters 32 are-disposed one abovethe other. and in close proximity so (that the material 17'may be rapidly. brought'up to the desired temperature. In the heating zone, however, the infra-red heat-- ers 32 are disposedin evenly spaced apart relationr" r Accordingto iii'prfei-lai embodiment of the inven H tion,thesourceofinfra-red radiation" comprises a tubular quartz infra-red lamp which consists of a coiled tungsten filament extending through the relatively small bore of a quartz tube. Quartz infra-red lamps are preferred because the quartz tube is capable of'withstandin'g' high temperatures, having a meltingpoint' of approximately 3200-'F.

In order to more efficiently utilize the'ener'gyoutput 'of the heaters 32, a pair of parallel, close ly spaced, elon' gate, water cooled reflector"

plates

36 and 37 extend upwardly from'the lower end of the-furnace chamber'25 and around'the upper roll 28 "tothe upper end' of the cooling zone and between the heaters 32 and the tank 25. In addition, as seen in'FIG. 3 -a pair of generally planar, rectangular, water cooled, side reflective plates 39 are disposed adjacent the sides of the reflectiveplates '36 and 37. While the'heat reflectors36, 37 and 39 may be'of any suitable material, polished aluminum has been found to be satisfactory.

'As seen in FIG. 3; eachof the lamp assemblies 32 extends across one side "of the furnace tank 25-parallel to the material 17. In order to support each'heate'r 'assem-' bly 32 in this manner and to allow for the replacement of the lamps 33, the tank 25 has a plurality of pairs of horizontally aligned apertures 43'for receiving lamp supporting assemblies 44. As seen in greater detail in FIG. each lamp supporting assembly 44 includes a cylindrical section 45 which extends through theopening 43 and which has an outer peripheral flange 46s'uitably aflixed to the periphery of said opening. A circular base plate 48 is aflixed to the inner end of the cylindrical section 45 and has a central aperture50'. A circular mounting plate 52'is disposed adjacentthe plate 48 for supporting the assembly'44 within'the chamber 12'.

More specifically, the'support plate 52 is secured to the baseplate 48 by means of screws 53 which extend through aligned tapped

holes

54 and 55 in the mounting consists of a pair of hollow, parallel, water cooled copper plate- 52 and the base plate 48, respectively.- An annular gasket 57, disposed in a groove formed in the mounting plate 52,- provides a sealbetween said mounting plate and the base plate 48. 7 "The mounting plate 52 is-also provided with a central aperture 58'which is coaxial with the aperture'50 in the base plate 48 for allowing a lamp support-member 5 9 of the assemb'ly 44 to extend into the tank 25.

In the preferred embodiment of the inventiom'shown in FIG. 5, the lamp support member =59includes a hollow, generally tubular section 60 which extendsthrough the aperture 58 in the support plate 52* and a radially extending'flange 63 at its upper end which engages the mounting plate 52. A second annular gasket 62 provided in a groove member 59 and terminal cap 64 are of electrically insulating material to insulate the terminal 72 from the tank 25.

One end of each of the reflectors 34 is aflixed to the inner surface of the base plate 48 by means of a plurality of elongate L-shaped bracket'members which are affixed atone end to the edge of said reflector andat their oppo; site endsto' the inner. surface oL-saidtplate I In the embodiment of FIG. 5, the lamp 33-is.dir.ectly exposed to" the interior of-the furnace chamber 25. In an alternate embodiment of the invention shown in FIG. 7, an elongate quartz tube 80 enclosed the lamp 33. The quartz tube 80 in the embodiment 'of FIG. 7 replaces the lamp supportfmember- 59' and extends through a pair of aligned openings in the tank 25...This embodiment is provided in installations where highoperating ,yoltages pro hibit the exposure of the lamp terminals to the vacuum within the chamber 25 to insure against the possibility of eorona discharges. In addition, if it is desirable to have thelamps 33 operating at a cooler temperature, the end of 'the quartz tubc Stl can, be.,.c ,onnected to a source of cooling gas.

"Referrmg again to FIGS. 1 and 3, the cooling zone plates 84 which are disposed adjacent the opposite'sides of the material 17 and above the exit roller 30. A cooling waterconnection is provided at 86 to the plates '84. In addition, an elongate, rectangular reflector 87 isprovided adjacent the innermost of the plates 84' to reflect'radiation from the heat'sources 32.

It will be appreciated that because the heat sources 32 are in no way'incompatible with a vacuum system, they may be located directly within the vacuum chamber. As

' a result, a separate vacuum chamber is not required. In

prior art furnaces, on the other hand,-where gas'fired heaters wereemployed, it was necessary to provide a separate vacuum chamber within the furnace itself.

In adidtion, because the material is heatedby infra-red sources, the heat is radiated directly to the material so thatthere is littleor no heating of the furnace'itself. As a result, while the material may be heated to temperatures of approximately 1650 F., required for the annealing of titanium, no expensive refractory linings are reformed in the margin of aperture 58, seals the juncture afiixed to the mounting plate 52 by screws 67. An annular gasket 68 disposed in a groove formed irr'the flange 65 seal's its juncture with the flange/63. In addition, the terminal cap 64 has an integral termmal' guard o whlchi 1 vacuum chamber comprising asealed metallic shell, means surrounds one end of an electrically conductive terminal 7Z'extending axially through'the terminal cap 64 1 The "end of the lamp 33 is further supported within the tubular sec'tion60' of member 59bymeans of alam'p support element 74 shown in FIG. 6.'The element 74 in;

quired for the furnace chamber 25, as in the case of conventional annealing furnaces.

Also, because the heat is radiated directly from the heat source to the material being treated, it is not necessary for the furnace to be-brought up to operating temperature as in the case of conventional furnaces. As a result, the radiation sources may be de-energized between operations and re-energized only a short period of time before an operation is to begin.

While the invention has been discussed with respect to one particular type of furnace, it is not intended to be limited thereby but only by the scope of the appended claims. In addition, while the'invention has been discussed with respect to quartz infra-red lamps, it will be 7 p understood that any self-contained source of infra-red lamp support member 59 and the terminal =cap 64 are radiation which is capable of withstanding the high temperatures involved, may be employed. I claim:

1. A, metal treating vacuum furnace" having an unlined for evacuating said chamber, means for conducting elongate strip material from an atmospheric environment into and out of saidchamber, heating means. disposed within said vacuum chamber and comprising a plurality of infrared lamps disposed opposed tosaid material. 1

-32. A metal treating vacuum furnace having a vacuum chamber comprising a sealed metallic shell, means for. evacuating said chamber, means for conductingelongate strip material from'an atmospheric environment into and out of said chamber, heat-ing means disposed within said chamber and comprising a plurality of quartz crystal lamps in spaced apart relation and opposedto-said material.

3. A metal treating vacuum furnace having a vacuum chamber comprising a sealed metallic shell, means for evacuating said chamber, means for conducting elongate strip material from an atmospheric environment into and out of said chamber, heating means disposed within said chamber and comprising a plurality of infra-red lamps in spaced apart relation and opposed to said material, and means for reflecting the infra-red radiation from said lamps onto said material.

4. A metal treating vacuum furnace having a vacuum chamber comprising a metallic shell, means for evacuating said chamber, means for conductnig elongate strip mate rial from an atmospheric environment into and out of said chamber, heating means disposed within said chamber and comprising a plurality of elongate quartz crystal lamps in spaced apart relation and opposed to said material, means for reflecting said infra-red radiation from said lamps onto said material, a plurality of apertures formed in said shell for receiving said lamps, first means mounted in said chamber and adjacent each of said apertures for releasably supporting said lamps within said chamber, and second means associated with said first means for sealing said apertures.

5. A vacuum furnace for the annealing of elongate strip material comprising an elongate vacuum chamber, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber, heating means disposed within said chamber and comprising a plurality of infra-red lamps, said lamps being arranged along a substantial portion of the path of said material within said elongate vacuum chamber and in opposed relation to said material, and cooling means disposed Within said chamher and extending for substantially the remaining portion of the path of said material within said chamber.

6. A vacuum furnace for the annealing of elongate strip material comprising an elongate vacuum chamber, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber, heating means disposed within said chamber and comprising a plurality of quartz crystal lamps, said lamps being arranged along a substantial portion of the path of said material within said elongate vacuum chamber and in opposed relation to said material, said heating means also including reflector means associated with said lamps, and elongate cooling means disposed within said chamber and extending for substantially the remaining portion of the path of said material within said chamber.

7. A vacuum furnace for the annealing of elongate strip material, including an elongate vacuum chamber comprising a metallic shell and having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber and between said areas, heating means disposed within said chamber and comprising a plurality of infra-red lamps arranged in an opposed relation to said material, a first plurality of said lamps being disposed in closely spaced relation in said entrance area, a second plurality of said lamps being arranged in spaced apart relation between said entrance area and said exit area, and elongate cooling means disposed in the exit area of said chamber.

8. A vacuum furnace for the annealing of elongate strip material, including an elongate vacuum chamber comprising :a sealed metallic shell having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber and between said areas, heating means disposed within said chamber and comprising a plurality of quartz crystal lamps arranged in an opposed relation to said material, a first plurality of said lamps being disposed in closely spaced relation in said entrance area, a second plurality of said.

lamps being arranged in spaced apart relation between said entrance area and said exit area, and elongate cooling means disposed in the exit area of said chamber, said heating means also including a parabolic reflector associated with each of said lamps, each of said lamps being disposed at the focal point of its respective reflector.

9. A vacuum furnace for the annealing of elongate strip material, including an elongate vacuum chamber comprising a sealed metallic shell having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmosphericenvironment into and out of said chamber and between said areas, heating means disposed within said chamber and comprising a plurality of quartz crystal lamps arranged in an opposed relation to said material, a first plurality of said lamps being disposed in closely spaced relation in said entrance area, a second plurality of said lamps being arranged in spaced apart relation between said entrance area and said exit area, and elongate cooling means disposed in the exit area of said chamber, said heating means also including a parabolic reflector associated with each of said lamps, each of said lamps being disposed at the focal point of its respective reflector, and elongate reflector means disposed between said heating means and said chamber and said cooling means.

10. A vacuum furnace for the annealing of elongate strip material, including an elongate vacuum chamber comprising a sealed metallic shell having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber and be tween said areas, heating means disposed within said chamber and comprising a plurality of quartz crystal lamps arranged in an opposed relation to said material, a first plurality of said lamps being disposed in closely spaced relation in said entrance area, a second plurality of said lamps being arranged in spaced apart relation between said entrance area and said exit area, and elonagte cooling means disposed in the exit area of said chamber, a plurality of apertures in said shell for receiving said lamps, said lamps being removably mounted within said apertures, means for sealing said apertures.

11. A vacuum furnace for the annealing of elongate strip material, including an elongate vacuum chamber comprising a metallic shell and having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber and between said areas, heating means disposed within said chamber and comprising a plurality of quartz crystal lamps arranged in an opposed relation to said material, a first plurality of said lamps being disposed in closely spaced rel-ation in said entrance area, a second plurality of said lamps being arranged in spaced apart relation between said entrance area and said exit area, and elongate cooling means disposed in the exit area of said chamber, an access opening formed in said shell adjacent each of said lamps, said lamps being removably mounted adjacent their respective openings, means for sealing said openings, said heating :means also including a parabolic reflector associated with each of said lamps, each of said lamps being disposed at the focal point of its respective reflectors, and elongate reflector means disposed between said heating means and said chamber :and said cooling means.

12.. A vacuum furnace for the annealing of elongate strip material, including an elongate unlined vacuum chamber comprising a metallic shell and having entrance and exit areas, means for evacuating said chamber, means for conducting said elongate strip material from an atmospheric environment into and out of said chamber and between said areas, heating means disposed within said chamber and comprising :a plurality of elongate quartz crystal lamps arranged in an opposed relation to said material and extending transversely thereof, a first plurality of said lamps being disposed in' closely spaced relation"- in said entrance area, a second plurality of said lamps being arranged in spaced apart relation between said entrance area and-said exit area, and elongate cooling means disposed in the exit area of said chamber, a pair of ali ned access openings formed in thesides of said chamber and adjacent the opposite ends of each of said lamps, an elongate quartz tube extending through each pair of openings and'sealingly engaging said openings, each of said lamps being removably mounted within one of said tubes, means for sealing said'openings, said heating means also includign a parabolic reflector associated-with each of said' lamps, each of said lamps being disposed at the focal point of its respective reflectors, and elongate reflector means disposed" between said heating :rneansand said chamber and'said cooling means. 7

I --Referencs Cited Y oNITED STATES ParEnTs' 2,278,136 13/1942 JoHN F. CAMPBELL, Primary Examiner.

J.- CLINE, Assistant Examiner.