US3397375A - Heating element - Google Patents

Heating element Download PDF

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Publication number
US3397375A
US3397375A US598455A US59845566A US3397375A US 3397375 A US3397375 A US 3397375A US 598455 A US598455 A US 598455A US 59845566 A US59845566 A US 59845566A US 3397375 A US3397375 A US 3397375A
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United States
Prior art keywords
heating element
terminal
resistance body
members
furnace
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US598455A
Inventor
Richard L Casper
Frank J Baumeister
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kennecott Corp
Original Assignee
Carborundum Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carborundum Co filed Critical Carborundum Co
Priority to US598455A priority Critical patent/US3397375A/en
Priority to GB54288/67A priority patent/GB1132559A/en
Priority to CH1706367A priority patent/CH484583A/en
Priority to DE19671615207 priority patent/DE1615207B2/en
Priority to SE16532/67A priority patent/SE347599B/xx
Application granted granted Critical
Publication of US3397375A publication Critical patent/US3397375A/en
Assigned to KENNECOTT CORPORATION reassignment KENNECOTT CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). EFFECTIVE DEC. 31, 1980 NORTH DAKOTA Assignors: BEAR CREEK MINING COMPANY, BEAR TOOTH MINING COMPANY, CARBORUNDUM COMPANY THE, CHASE BRASS & COPPER CO. INCORPORATED, KENNECOTT EXPLORATION, INC., KENNECOTT REFINING CORPORATION, KENNECOTT SALES CORPORATION, OZARK LEAD COMPANY, PLAMBEAU MINING CORPORATION, RIDGE MINING CORPORATION (ALL MERGED INTO)
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/02—Details
    • H05B3/06—Heater elements structurally combined with coupling elements or holders
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/148—Silicon, e.g. silicon carbide, magnesium silicide, heating transistors or diodes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/62—Heating elements specially adapted for furnaces
    • H05B3/64—Heating elements specially adapted for furnaces using ribbon, rod, or wire heater

Definitions

  • An electric heating element comprising a tubular resistance body having a hot zone section and a cold end terminal section engageable with an electrical contact.
  • a ceramic bulk fiber ⁇ filler is disposed within a controlled portion of the cold end terminal section to impede the flow of radiative heat toward the electrical contact area.
  • This invention relates -to heating elements and, more particularly, to terminal -assemblies used on high temperature heating elements.
  • the general purpose of the present invention is to provide a solution to the above problem by providing a new and improved terminal assembly for a heating element which permits the terminal contact .area to operate at cooler temperatures to materially increase the useful life of the heating element.
  • FIG. 1 is a top plan View of the heating element constrncted in accord-ance with the principles of this invention
  • FIG. 2 is an end elevational view of the heating element of FIG. l.
  • FIG. 3 is a fragmentary sectional View of a furnace illustrating the heating element of the present invention installed therein.
  • an electric lresistance heating element constructed in accordance with the principles of this invention comprises an elongated, hollow, tubular resist-ance body, generally designated 10, having a hot zone section 12 of a double spiral configuration, an end portion 14, and a split cold end terminal section 16.
  • Resistance body is preferably composed of a nonmetallic resistance material such Ias very dense, high-purity, self-bonded silicon carbide.
  • the split cold end terminal section 16 comprises a pair of laterally space-d, elongated members or legs 18 and 20 of substantially semicircular, trough shaped cross sections (FIG. 2), forming a substantially hollow, tubular chamber :and defining a pair of diametrically opposed slots 22 and 24.
  • Disposed in slots 22 and 24 adjacent an end portion 26 of resistance body 10 are a pair of elongated inserts or shims 28 and 30, respectively, which function as primary braces and insulators between legs 18 and 20.
  • the shims are preferably formed of alumina, it should be appreciated that the principles of this invention contemplate the use of any Istrong insulating ceramic material in lieu of alumina, if desi-red.
  • a ceramic bulk fiber filler 32 preferably of short staple, is provided to fill a controlled portion of the inside dianiet-er of the resistance body 10 in order to impede the flow of radiative heat in a direction toward end portion 26, thus maintaining the terminal area relatively cool.
  • the bulk fiber functions as a secondary brace between legs 18 and 20 to preclude an electrical short therebetween.
  • Means are provided for urging members 18 and 20 against shims 28 and 30, such means comprising a collar 34, preferably composed of a ceramic material and formed of four arcuate shaped members 36 having their inner surfaces, respectively, conforming to the outer cylindrical surface of resistance body 10. Also, collar 34 aids in securing the bulk fiber filler 32 in place and retaining the heating element in the heating chamber of a furnace. As shown in FIG. 2, members 36 are circumferentially spaced from each other to form openings for accommodating the yshims 28 and 30. A clamp 42 ⁇ is provided for hol-ding members 36 in engagement with resistance body 10. If desired, only two substantially semi-circular members may be substituted for the four members 36 that constitute collar 34 within the purview of the present invention.
  • the coating may be sprayed onto legs 18 and 20 or it may be applied in any conventional manner well-known in the art.
  • End portion 26 of resistance body 10 is adapted to be mounted within a split clip type of contact 46 comprising a pair of resilient metallic tongs 48 and 50 having arcuate shaped portions 52 and 54 respectively, conforming to the louter cylindrical surfaces of legs 18 and 20.
  • the clip 46 is composed of any suitable metal such as stainless steel or a high chrome, nickel base, heat resistant alloy for example, and may have -the inner surfaces of tongs 48 and 50 sprayed with a suitable electrical conducting material, if desired.
  • the bottom of clip 46 is electrically and mechanically secured to a pair of electrically conducting terminal straps 56 and 58 and mounted on la base 60, composed of a suitable insulating material, by means of bolt and nut combinations 62, respectively.
  • FIG. 3 shows the heating element protruding into the side wall 64 of a high temperature electric furnace
  • a terminal tube 68 formed ⁇ of a suitable high dielectric insulating material
  • Resistance body 10 is loosely fitted into the terminal tube 68 (shown exaggerated in FIG. 3) in Iorder to facilitate the replacement of the heating element in a furnace installation.
  • the terminal tube 68 is provided with a flange 70 abutting against the exterior surface of the furnace wall and the collar 34 of the heating element is disposed flush against the flange 70. It should be appreciated that collar 34 may be formed integral with the terminal tube 68, if desired, w-ithin the scope of the present invention.
  • a new and improved heating ⁇ element having a novel terminal assembly for minimizing heat radiation in the electrical cont-act area.
  • the heating element is held together and in place in a furnace installation and the electrical contact area is disposed exteriorly olf the furnace walls.
  • the element can be mounted to hang vertically downwardly from the roof of a furnace or project up through the bott-om of a furnace chamber. In lthe latter case, however, auxiliary support means would tbe necessary to maintain the element in an upright position.
  • Another :advantage residing in the device of the present invention is the provision of a thermal insulating ceramic bulk fiber ii-ller lwithin a vcontrolled portion of the inside ydiameter of the resistance body for preventing heat flow toward the electrical contact area.
  • a heating element comprising: an elongated resistance body having a hot zone section and a cold end section; said cold end section comprising a pair of laterally spaced elongated members having outer surfaces, respectively; a coat-ing of electrical conducting material deposited on said outer surfaces of said elongated members adjacent the ends thereof remote from said hot zone section; and insulating liller composed of a ceramic bulk fiber disposed between said laterally spaced elongated memlbers along a controlled portion thereof.
  • a heating element as dened in Iclaim 1 including a pair of insulating shims disposed between said laterally spaced elongated members.
  • a heating element as defined in claim 2 including means disposed about said laterally spaced elongated members for urging said members against said insulating shims.
  • a heating element as ⁇ defined in claim 4 in which said lends of said elongated members remote from said hot zone section are engageable with an electrical contact.

Landscapes

  • Resistance Heating (AREA)
  • Furnace Details (AREA)

Description

Aug. 13, `1968 .vvy M R. L.. CASPER ET Al.
HEATING ELEMENT Filed Dec. 1. 1.966
lFig. 2
INVENTOR.
RICHARD L. CASPER FRANK J. BAUMEISTER United States Patent O 3,397,375 HEATING ELEMENT Richard L. Casper, Grand Island, and Frank J. Baumeister, Lockport, N.Y., assignors to The Carborundum Company, Niagara Falls., N.Y., a corporation of Delaware Filed Dec. 1, 1966, Ser. No. 598,455 7 Claims. (Cl. 338-330) ABSTRACT F THE DISCLOSURE An electric heating element comprising a tubular resistance body having a hot zone section and a cold end terminal section engageable with an electrical contact. A ceramic bulk fiber `filler is disposed within a controlled portion of the cold end terminal section to impede the flow of radiative heat toward the electrical contact area.
This invention relates -to heating elements and, more particularly, to terminal -assemblies used on high temperature heating elements.
One of the critical problems encountered in the utilization of heating elements is that :excessive temperatures due to thermal conductivity occurring in the electrical contact area and the inside diameter of the element a-djacent the terminal portion result in the fracturing and/or burning up of these portions causing premature failure of the heating elements.
The general purpose of the present invention is to provide a solution to the above problem by providing a new and improved terminal assembly for a heating element which permits the terminal contact .area to operate at cooler temperatures to materially increase the useful life of the heating element.
It -is therefore an object of the present invention to provide a new and improved heating element.
lt -is 'another object of the present invention to provide .ia new and improved heating element having a novel terminal assembly.
It is a further object of the present invention to provide a new and improved heating element having a novel terminal assembly which is durable, rugged, and simple in construction.
It is still another object of the presen-t invention to provide a new and improved heating element having a novel terminal assembly which maintains the electrical contact area at relatively cool temperatures.
It is still a further object of the present invention to provide a new and improved heating element having an insulating filled disposed within the body of the element at the electrical contact area thereof.
These and other objects of the present invention will become more apparent upon consideration of the foll-owing detailed description thereof when taken in conjunction with the following drawings, in whi-ch:
FIG. 1 is a top plan View of the heating element constrncted in accord-ance with the principles of this invention;
FIG. 2 is an end elevational view of the heating element of FIG. l; and
FIG. 3 is a fragmentary sectional View of a furnace illustrating the heating element of the present invention installed therein.
Referring to the drawings in detail, -it will be seen that an electric lresistance heating element constructed in accordance with the principles of this invention comprises an elongated, hollow, tubular resist-ance body, generally designated 10, having a hot zone section 12 of a double spiral configuration, an end portion 14, and a split cold end terminal section 16. Resistance body is preferably composed of a nonmetallic resistance material such Ias very dense, high-purity, self-bonded silicon carbide.
The split cold end terminal section 16 comprises a pair of laterally space-d, elongated members or legs 18 and 20 of substantially semicircular, trough shaped cross sections (FIG. 2), forming a substantially hollow, tubular chamber :and defining a pair of diametrically opposed slots 22 and 24. Disposed in slots 22 and 24 adjacent an end portion 26 of resistance body 10 are a pair of elongated inserts or shims 28 and 30, respectively, which function as primary braces and insulators between legs 18 and 20. Although the shims are preferably formed of alumina, it should be appreciated that the principles of this invention contemplate the use of any Istrong insulating ceramic material in lieu of alumina, if desi-red. v
A ceramic bulk fiber filler 32, preferably of short staple, is provided to fill a controlled portion of the inside dianiet-er of the resistance body 10 in order to impede the flow of radiative heat in a direction toward end portion 26, thus maintaining the terminal area relatively cool. Moreover, the bulk fiber functions as a secondary brace between legs 18 and 20 to preclude an electrical short therebetween.
Means are provided for urging members 18 and 20 against shims 28 and 30, such means comprising a collar 34, preferably composed of a ceramic material and formed of four arcuate shaped members 36 having their inner surfaces, respectively, conforming to the outer cylindrical surface of resistance body 10. Also, collar 34 aids in securing the bulk fiber filler 32 in place and retaining the heating element in the heating chamber of a furnace. As shown in FIG. 2, members 36 are circumferentially spaced from each other to form openings for accommodating the yshims 28 and 30. A clamp 42`is provided for hol-ding members 36 in engagement with resistance body 10. If desired, only two substantially semi-circular members may be substituted for the four members 36 that constitute collar 34 within the purview of the present invention.
A coating of any suitable electrical conducting material `44, such as aluminum by way of example, is deposited on the exterior surface lof legs 18 and 20 `adjacent end portion 26 (FIG. l) in order to provide terminals for the resistance body 10. The coating may be sprayed onto legs 18 and 20 or it may be applied in any conventional manner well-known in the art.
End portion 26 of resistance body 10 is adapted to be mounted within a split clip type of contact 46 comprising a pair of resilient metallic tongs 48 and 50 having arcuate shaped portions 52 and 54 respectively, conforming to the louter cylindrical surfaces of legs 18 and 20. The clip 46 is composed of any suitable metal such as stainless steel or a high chrome, nickel base, heat resistant alloy for example, and may have -the inner surfaces of tongs 48 and 50 sprayed with a suitable electrical conducting material, if desired. The bottom of clip 46 is electrically and mechanically secured to a pair of electrically conducting terminal straps 56 and 58 and mounted on la base 60, composed of a suitable insulating material, by means of bolt and nut combinations 62, respectively.
One manner of installing the heating element of the present `invention is exemplified in FIG. 3 which shows the heating element protruding into the side wall 64 of a high temperature electric furnace, Normally, a terminal tube 68, formed `of a suitable high dielectric insulating material, is snugly fitted `into a bore 69 of the furnace and envelopes a portion of the resistance body 10 to preclude the possible shorting of the terminal ends caused by the full element voltage which exists along the entire length of the terminal. Resistance body 10 is loosely fitted into the terminal tube 68 (shown exaggerated in FIG. 3) in Iorder to facilitate the replacement of the heating element in a furnace installation. The terminal tube 68 is provided with a flange 70 abutting against the exterior surface of the furnace wall and the collar 34 of the heating element is disposed flush against the flange 70. It should be appreciated that collar 34 may be formed integral with the terminal tube 68, if desired, w-ithin the scope of the present invention.
As a result of the present linvention, a new and improved heating `element is provided having a novel terminal assembly for minimizing heat radiation in the electrical cont-act area. By the provision fo a ceramic collar, the heating element is held together and in place in a furnace installation and the electrical contact area is disposed exteriorly olf the furnace walls. Moreover, the element can be mounted to hang vertically downwardly from the roof of a furnace or project up through the bott-om of a furnace chamber. In lthe latter case, however, auxiliary support means would tbe necessary to maintain the element in an upright position.
Another :advantage residing in the device of the present invention is the provision of a thermal insulating ceramic bulk fiber ii-ller lwithin a vcontrolled portion of the inside ydiameter of the resistance body for preventing heat flow toward the electrical contact area.
A preferred embodiment of this invention having been described and illustrated, it is to be -realized that modifications thereof may be made without departing from the broad spirit and scope of this invention as defined in the appended claims.
I claim:
1. A heating element comprising: an elongated resistance body having a hot zone section and a cold end section; said cold end section comprising a pair of laterally spaced elongated members having outer surfaces, respectively; a coat-ing of electrical conducting material deposited on said outer surfaces of said elongated members adjacent the ends thereof remote from said hot zone section; and insulating liller composed of a ceramic bulk fiber disposed between said laterally spaced elongated memlbers along a controlled portion thereof.
2. A heating element as dened in Iclaim 1 including a pair of insulating shims disposed between said laterally spaced elongated members.
3. A heating element as defined in claim 2 including means disposed about said laterally spaced elongated members for urging said members against said insulating shims.
4. A heating element as defined in claim 3 -in which said urging means comprises a collar formed of a plurality of elements, and a clamp positioned about said plurality of elements.
5. A heating element as `defined in claim 4 in which said lends of said elongated members remote from said hot zone section are engageable with an electrical contact.
v6. A heating element as defined in claim 5 in which said laterally spaced elongated members are substantially semiicircullar vin cross section, respectively, and dene a hollow chamber for receiving said filler material.
7. A heating element as defined in claim 6 in which said elongated resistance body is composed of dense, selfbonded silicon carbide.
References Cited UNITED STATES PATENTS 3,307,136 2/1967 Fitz/er et al 338--330 X 3,3 3 6,431 8/ 1967 Biddulph 13--25 FOREIGN PATENTS 838,917 f 6/1920 Great Britain.
LARAMIE E. ASKIN, Primary Examiner.
E. GOLDBERG, Assistant Examiner.
US598455A 1966-12-01 1966-12-01 Heating element Expired - Lifetime US3397375A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US598455A US3397375A (en) 1966-12-01 1966-12-01 Heating element
GB54288/67A GB1132559A (en) 1966-12-01 1967-11-29 Heating element
CH1706367A CH484583A (en) 1966-12-01 1967-11-30 Electric heating element
DE19671615207 DE1615207B2 (en) 1966-12-01 1967-11-30 ELECTRIC HEATING ELEMENT
SE16532/67A SE347599B (en) 1966-12-01 1967-12-01

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CH (1) CH484583A (en)
DE (1) DE1615207B2 (en)
GB (1) GB1132559A (en)
SE (1) SE347599B (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3729570A (en) * 1971-09-20 1973-04-24 Btu Eng Corp Modular heater furnace
US3800057A (en) * 1972-07-24 1974-03-26 Preussag Ag Electrically heated furnace utilizing ceramic heating elements
US3842319A (en) * 1972-02-04 1974-10-15 Tappan Co Gas igniter
US3859500A (en) * 1973-09-17 1975-01-07 Squared R Element Company Inc Heating element
US3859501A (en) * 1973-09-17 1975-01-07 Squared R Element Company Inc Three-phase heating element
US3928910A (en) * 1972-09-18 1975-12-30 Tappan Co Gas igniter
US4090054A (en) * 1976-10-12 1978-05-16 Brown Boveri Corporation Electrical preheating apparatus
USRE29853E (en) * 1972-09-18 1978-11-28 The Tappan Company Gas igniter
US4475029A (en) * 1982-03-02 1984-10-02 Nippondenso Co., Ltd. Ceramic heater

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4272639A (en) * 1979-08-01 1981-06-09 Btu Engineering Corporation Helically wound heater
DE3332279A1 (en) * 1983-09-07 1985-04-04 bfb dental GmbH, 6451 Ronneburg CASTING DEVICE FOR DENTAL WORK
DE102011006847A1 (en) * 2011-04-06 2012-10-11 Schunk Kohlenstofftechnik Gmbh Method for producing a resistance heating element and resistance heating element

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB838917A (en) * 1955-01-25 1960-06-22 Siemens Planiawerke Ag Improvements in or relating to heating conductors for resistance heated electric furnaces operating at temperatures above 1400 c
US3307136A (en) * 1961-07-20 1967-02-28 Siemens Planiawerke Ag Contact layer for a siliconcontaining material
US3336431A (en) * 1964-04-07 1967-08-15 United States Borax Chem Electric furnace

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB838917A (en) * 1955-01-25 1960-06-22 Siemens Planiawerke Ag Improvements in or relating to heating conductors for resistance heated electric furnaces operating at temperatures above 1400 c
US3307136A (en) * 1961-07-20 1967-02-28 Siemens Planiawerke Ag Contact layer for a siliconcontaining material
US3336431A (en) * 1964-04-07 1967-08-15 United States Borax Chem Electric furnace

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3729570A (en) * 1971-09-20 1973-04-24 Btu Eng Corp Modular heater furnace
US3842319A (en) * 1972-02-04 1974-10-15 Tappan Co Gas igniter
US3800057A (en) * 1972-07-24 1974-03-26 Preussag Ag Electrically heated furnace utilizing ceramic heating elements
US3928910A (en) * 1972-09-18 1975-12-30 Tappan Co Gas igniter
USRE29853E (en) * 1972-09-18 1978-11-28 The Tappan Company Gas igniter
US3859500A (en) * 1973-09-17 1975-01-07 Squared R Element Company Inc Heating element
US3859501A (en) * 1973-09-17 1975-01-07 Squared R Element Company Inc Three-phase heating element
US4090054A (en) * 1976-10-12 1978-05-16 Brown Boveri Corporation Electrical preheating apparatus
US4475029A (en) * 1982-03-02 1984-10-02 Nippondenso Co., Ltd. Ceramic heater

Also Published As

Publication number Publication date
DE1615207B2 (en) 1976-11-04
DE1615207A1 (en) 1970-05-06
CH484583A (en) 1970-01-15
SE347599B (en) 1972-08-07
GB1132559A (en) 1968-11-06

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Owner name: KENNECOTT CORPORATION

Free format text: MERGER;ASSIGNORS:BEAR CREEK MINING COMPANY;BEAR TOOTH MINING COMPANY;CARBORUNDUM COMPANY THE;AND OTHERS;REEL/FRAME:003961/0672

Effective date: 19801230