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Publication numberUS3804967 A
Publication typeGrant
Publication dateApr 16, 1974
Filing dateOct 13, 1972
Priority dateOct 13, 1972
Publication numberUS 3804967 A, US 3804967A, US-A-3804967, US3804967 A, US3804967A
InventorsWerych E
Original AssigneeSola Basic Ind Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Rectangular tube diffusion furnace
US 3804967 A
A diffusion furnace has a processing member with a rectangular cross section having an arcuate-like top wall and a heating element of a substantially elliptical-like cross section surrounding the processing member.
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Description  (OCR text may contain errors)

United States Patent 1191 Johnson 219/390 Wer ch A r. 16 1974 RECTANGULAR TUBE DIFFUSION 1,144,981 6/1915 Lightfoot... 219/390 x FURNACE 1,500,609 7/1924 Dixon 219/390 X 2,274,190 2/1942 Cramer 219/390 Inventor: Ewald y Elm Grove. 3,299,196 1/1967 Lasch,Jr. et a1. 13/24 3,311,694 31967 L 11,]. 13 24 [73] Assgnee Bas'c f 3,406,242 10/1968 13/22 Mllwaukee 3,409,727 11/1968 Hampton 13/20 22 Filed: Oct. 13 1972 3,541,293 11/1970 MacDonald et al. 219/390 21 APPL 297,205 FOREIGN PATENTS OR APPLICATIONS 693,878 7/1953 Great Britain 219/388 '[52] US. Cl 13/22, 13/25, 2l9/388,

219/390, 219/406 Primary ExaminerVolodymyr V. Mayewsky s 1 Int. Cl. H0511 3/66 Attorney, 8 m and Moore [58] Field of Search 219/388, 390, 406, 411,

219/553; 13/20, 22, 24, 25 57 ABSTRACT [56] References Cited A diffusion furnace has a processing member with a rectangular cross section having an arcuate-like top UNITED STATES PATENTS wall and a heating element of a substantially elliptical- 714,373 11/1902 Hewett et a1. 219/390 like cross section surrounding the processing member. 904,529 l1/1908 Hammond et a]... 1,035,596 8/1912 1 Claim, 4 Drawing Figures 1 RECTANGULAR TUBE DIFFUSION FURNACE The present invention relates to diffusion furnaces and particularly to the heating element and processing or tube member through which work to be processed is passed or held.

A conventional diffusion furnace essentially comprises a hollow processing member or tube constructed of a suitable material, such as quartz, and surrounded by a heating element in the form of a helical coil. It has been generally considered to be desirable to have the heating element positioned as close as possible to the processing member. Accordingly, the cross-sectional configuration of the heating element was made similar to that of the cross-sectional configuration of the processing member, and in many cases, the heating element fitted very closely around the processing member. Thus, where diffusion furnaces for different operations were provided with processing members of various cross sections, such as circular, square, or rectangular, the heating elements for these furnaces had the corresponding cross-sectional shapes. This introduced certain difficulties in the manufacture of diffusion furnaces since it was necessary to manufacture and stock heating elements having the same shapes as the processing members. Further, difficulties were frequently encountered in mounting such heating elements upon the processing members.

One of the objects of the present invention is to provide an improved diffusion furnace.

Another of the objects of the invention is to provide an improved construction of the heating element with respect to the processing member.

According to one aspect of the present invention, a diffusion furnacemay comprise a substantially hollow processing member or tube having a processing zone therein. The processing member has a rectangular cross section with the upper wall or roof having an arcuate-like section. A heating element surrounds the processing member and supplies heat to the processing zone. The heating element has a substantially elliptical cross section and comprises a helical coil. Portions of the heating element opposite respective faces of the rectangular processing member are slightly flattened.

These and other objects, advantages and features of the invention will become apparent from the following description and drawings which are merelyexemplary.

In the drawings:

FIG. 1 is an overall perspective view of a diffusion furnace incorporating the present invention with portions of the furnace being cut away;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1; and

FIG. 4 is a side elevational view ofthe heating element incorporated in the diffusion furnace of this invention.

Proceeding next to the drawings wherein like reference symbols indicate the same parts throughout the various views, a specific embodiment of the present invention will be described in detail.

As may be seen in FIG. I, a diffusion furnace incorporating the present invention is indicated generally at 10 and comprises a tubular processing member 11 formed of a suitable material, such as quartz, and having a rectangular cross section with an arcuate upper wall or roof such as shown in FIG. 2. The processing member 11 is surrounded by a heating element 13, comprising a helical coil and having the cross-sectional shape as shown in FIG. 2.

As mentioned, the roof or upper portion is arcuately shaped.

The processing member 11 can be supported on strips or blocks 12 carried on ceramic structure 15.

The heating element 13 is substantially elliptical-like in shape but has portions thereof flattened which are opposite the several faces of the processing tube. The result is a substantially elliptical-like shape having opposed portions thereof flattened as shown in FIG. 2.

The heating element is supported within the furnace in a suitable manner, and a plurality of ceramic separators 14 can be provided to maintain separation between turns of the heating element. The separators are cemented to a tubular ceramic structure 15 which can be enclosed in an outer casing 16 having substantially the same cross-sectional shape as the heating element 13.

Flanges 17 and 18 of a suitable material, such as refractory or ceramic, are mounted within the casing 16 on opposite ends of the heating element 13, and each is provided with an opening 19 and 20 which is substantially of the same size as the inner opening of the tubular processing member 11. I

In the form shown in FIG. 4, the furnace is provided with three zones as defined by the turns of the heating coil. The turns of the several zones are connected by alloy strips 21 and 22 to suitable sources of electrical energy.

It should be apparent that variations can be made in details of construction without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

1. In a diffusion furnace including a ceramic outer tubular structure, the combination of a tubular processing ceramic member of generally rectangular cross section in said outer structure and having an arcuately shaped roof and a processing zone therein, said processing member being supported by extruded quartz block means, an electrical helical coil heating element surrounding said processing member and mounted in said ceramic outer structure by ceramic separating means attached to said outer structure, and metal conductive strips extending through said outer structure and connected to said coil heating element and a source of electrical energy to supply current to said coil heating element and thereby to heat said processing zone, said heating element having a substantially elliptical-like cross section and wherein the major axis thereof is parallel to the longer sides of the rectangular processing member and opposed sides are generally flattened with reference to the straight side walls of said processing member.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US714373 *Feb 17, 1902Nov 25, 1902Ashley M HewettElectrical dental furnace.
US904529 *Feb 27, 1908Nov 24, 1908S S White Dental Mfg CoElectric-furnace muffle.
US1035596 *Dec 1, 1910Aug 13, 1912Manfred J JohnsonElectric furnace.
US1144981 *Nov 18, 1911Jun 29, 1915Edwin N LightfootElectric heater.
US1500609 *Mar 28, 1921Jul 8, 1924H L Dixon CompanyAnnealing leer
US2274190 *Oct 21, 1940Feb 24, 1942Harold F CramerElectrical meat cooker
US3299196 *Jul 13, 1964Jan 17, 1967Electroglas IncDiffusion furnace
US3311694 *May 28, 1965Mar 28, 1967Electroglas IncDiffusion furnace utilizing high speed recovery
US3406242 *May 4, 1967Oct 15, 1968Karl A. LangDiffusion furnace hearth plate
US3409727 *Jun 21, 1967Nov 5, 1968Electroglas IncDiffusion furnace
US3541293 *Oct 29, 1968Nov 17, 1970Elliott E La FrienierMuffle furnace
GB693878A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4208573 *Nov 9, 1977Jun 17, 1980Vita Zahnfabrik H. Rauter KgKiln utilizing infrared radiation in the range of 0.7 to 1.5 μm to heat dental ceramic material
US4233496 *Jun 28, 1978Nov 11, 1980Viscosuisse S.A.Apparatus for removal of residues by means of pyrolysis
US4292276 *Mar 9, 1979Sep 29, 1981Ibigawa Electric Industry Co., Ltd.Apparatus for producing silicon carbide
US4347431 *Jul 25, 1980Aug 31, 1982Bell Telephone Laboratories, Inc.Diffusion furnace
US4849608 *Feb 11, 1988Jul 18, 1989Dainippon Screen Mfg. Co., Ltd.Apparatus for heat-treating wafers
US4900518 *Dec 2, 1988Feb 13, 1990Daidosanso K. K.Gaseous organic/inorganic thermal cracker for vacuum chemical epitaxy
US4950870 *Nov 21, 1988Aug 21, 1990Tel Sagami LimitedHeat-treating apparatus
US5128515 *Apr 30, 1991Jul 7, 1992Tokyo Electron Sagami LimitedHeating apparatus
US8203107Jul 5, 2011Jun 19, 2012Mastrad, S.A.Microwavable cooking implements and methods for crisping food items using the same
EP0052230A2 *Oct 12, 1981May 26, 1982Antonio PetrelliElectric heater for industrial processing machinery in general
U.S. Classification373/119, 373/137, 219/406, 219/390, 219/388
International ClassificationF27D11/02, H05B3/66, H05B3/62, H05B3/16, F27D11/00
Cooperative ClassificationH05B3/66, H05B3/16, F27D11/02
European ClassificationH05B3/16, H05B3/66, F27D11/02
Legal Events
Aug 2, 1990ASAssignment
Effective date: 19900731
Aug 2, 1990AS02Assignment of assignor's interest
Effective date: 19900731