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1. WO1982003305 - SHIELDED HEATING ELEMENT HAVING INTRINSIC TEMPERATURE CONTROL

Publication Number WO/1982/003305
Publication Date 30.09.1982
International Application No. PCT/US1982/000303
International Filing Date 11.03.1982
IPC
B23K 3/047 2006.1
BPERFORMING OPERATIONS; TRANSPORTING
23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
3Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
04Heating appliances
047electric
CPC
B23K 3/0475
BPERFORMING OPERATIONS; TRANSPORTING
23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
3Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
04Heating appliances
047electric
0475using induction effects, e.g. Kelvin or skin effects
H05B 3/12
HELECTRICITY
05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
3Ohmic-resistance heating
10Heater elements characterised by the composition or nature of the materials or by the arrangement of the conductor
12characterised by the composition or nature of the conductive material
H05B 3/42
HELECTRICITY
05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
3Ohmic-resistance heating
40Heating elements having the shape of rods or tubes
42non-flexible
Applicants
  • IRIS ASSOCIATES [US]/[US]
Inventors
  • CARTER, Philip, S.
  • KRUMME, John, F.
Agents
  • ROSE, Howard, L.
Priority Data
243,77716.03.1981US
Publication Language English (en)
Filing Language English (EN)
Designated States
Title
(EN) SHIELDED HEATING ELEMENT HAVING INTRINSIC TEMPERATURE CONTROL
(FR) ELEMENT CHAUFFANT BLINDE POURVU D'UNE COMMANDE DE TEMPERATURE INTRINSEQUE
Abstract
(EN) There are many situations requiring temperature regulation in heating elements which the prior art feedback control systems are not capable of handling adequately. In order to provide a temperature regulation in a narrow range around the Curie temperature, the electrical heating element of the present invention is consisted of a core 7 (25) or a substrate 35 of a non-magnetic material having high thermal and electrical conductivity, clad with a surface layer 9 (27, 37) of a ferromagnetic material of relatively low electrical conductivity. When the heating element is energized by an electrical source 3 (41) of high frequency alternating current, the skin effect initially confines current flow principally to the surface layer of ferromagnetic material. As temperature rises into the region of the Curie temperature of the ferromagnetic material, however, the decline in magnetic permeability of the ferromagnetic material causes a significant lessening of the skin effect, permitting migration of current into the high conductivity non-magnetic core or the substrate, thereby simultaneously enlarging the cross-sectional area of the current flow path and expanding it into the highly conductive material; the resistance of the heating element becomes less due to both causes. By selecting the proper frequency for energization, by regulating the source to produce constant current, and by selecting dimensions and material parameters for the heating element, temperature regulation in a narrow range around the Curie temperature of the ferromagnetic material can be produced, despite considerable fluctuations in thermal load.
(FR) Dans nombre de situations necessitant un reglage de la temperature dans des elements chauffants, les systemes de commande a reaction de l'art anterieur n'ont pas permis un controle convenable. Afin de permettre un reglage de la temperature dans une gamme etroite autour du point de Curie, l'element chauffant electrique de la presente invention se compose d'un noyau 7 (25) ou d'un substrat (35) d'un materiau non magnetique possedant une conductivite electrique et thermique elevee, recouvert d'une couche de surface 9 (27, 37), d'un materiau ferromagnetique presentant une conductivite electrique relativement faible. Lorsque l'element chauffant est mis sous tension par une source electrique 3 (41) d'un courant alternatif a haute frequence, l'effet de peau limite initialement le flux de courant principalement a la couche de surface du materiau ferromagnetique. Toutefois, au fur et a mesure que la temperature augmente dans la region du point de Curie du materiau ferromagnetique, la decroissance de la permeabilite magnetique du materiau ferromagnetique provoque une diminution sensible de l'effet de peau, permettant la migration du courant dans le noyau non magnetique a conductivite elevee du substrat, elargissant simultanement la section transversale du chemin du flux de courant et l'etendant dans le materiau hautement conducteur; la resistance de l'element chauffant diminue a cause de ces deux facteurs. En choisissant la frequence indiquee pour la mise sous tension, en reglant la source de maniere qu'elle produise un courant constant et en selectionnant les parametres relatifs aux dimensions et aux materiaux utilises pour l'element chauffant, l'on peut obtenir un reglage dans une gamme etroite autour du point de Curie du materiau ferromagnetique, malgre des fluctuations considerables de la charge thermique.
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