US3571551A - High frequency heating apparatus - Google Patents

High frequency heating apparatus Download PDF

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Publication number
US3571551A
US3571551A US810650A US3571551DA US3571551A US 3571551 A US3571551 A US 3571551A US 810650 A US810650 A US 810650A US 3571551D A US3571551D A US 3571551DA US 3571551 A US3571551 A US 3571551A
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US
United States
Prior art keywords
wire
high frequency
coaxial
resonator
line
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
US810650A
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English (en)
Inventor
Naoyuki Ogasawara
Takao Namiki
Katsutoshi Sone
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.)
Furukawa Electric Co Ltd
Original Assignee
Furukawa Electric Co Ltd
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
Priority claimed from JP472269A external-priority patent/JPS4837295B1/ja
Application filed by Furukawa Electric Co Ltd filed Critical Furukawa Electric Co Ltd
Application granted granted Critical
Publication of US3571551A publication Critical patent/US3571551A/en
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
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/78—Arrangements for continuous movement of material
    • H05B6/782—Arrangements for continuous movement of material wherein the material moved is food

Definitions

  • the principal object of the present invention is to provide a novel high frequency heating apparatus free from the above disadvantages of the conventional heating apparatus.
  • Another object of the invention is to provide a high frequency heating apparatus capable of continuously heating either or both of a metallic conductor and a dielectric material provided thereon.
  • a further object of the invention is to provide a high frequency heating apparatus, small in size and capable of rapid temperature control with quick thermal response.
  • shorting elements in noncontacting relationship to the object to be heated, both the shorting elements and the transmission line together constituting a high frequency resonator.
  • FIG. 2 is a view, partly in section, of a feeder for feeding high frequency power to a coaxial line in noncontacting relationship to a heating object as an inner conductor;
  • FIG. 5 is a perspective view of the apparatus in FIG. 4;
  • FIG. 8b is a schematic longitudinal view of a measuring apparatus used for obtaining the characteristics shown in FIG. 8a;
  • FIG. 9 illustrates a lossy circuit structure
  • FIG. It is a diagram showing input voltage standing wave ratio (as function of frequency) of a cavity resonator with or without the lossy circuit in FIG. 9;
  • FIG. ill illustrates an application of the high frequency heating apparatus of the invention to the manufacture of an electric wire insulated with a foamed synthetic resin.
  • the reference number 1 designates a wire to be heated, such as a bare copper wire, a synthetic resin coated electric wire, an enameled wire or the like, which, driven by a suitable device not shown, runs in the direction shown with an arrow.
  • a pipe-shaped outer conductor number 2 is arranged so as to surround coaxially the wire ll, and both constitute a high loss coaxial line 2.
  • Coupled with the outer conductor 2 is a power feeder 3 in noncontacting relationship to the wire l as an inner conductor.
  • the feeder 3 is a coaxial line waveguide transducer with the wire 1 as the center conductor of coaxial line.
  • lts coupling degree can be adjusted by means of a movable shorting plate 33 with an adjusting screw 34 in a waveguide section 31 and matching stubs 36 screwed into another waveguide section 32.
  • the waveguide section 32 is connected in series to a directional coupler and an isolator 5.
  • the isolator in turn is connected to a magnetron mount consisting of a magnetron tube 7, a waveguide 6, and a short plunger 61.
  • the feeder 3, directional coupler 4, isolator 5, and waveguide 6 together constitute a waveguide system for carrying high frequency power from the power source 7 to the coaxial line 2.
  • the directional coupler 4 is equipped with a detector and a galvanometer (not shown), and serves to monitor the incident power to the coaxial line 2' and the reflected power from the feeder 3.
  • the isolator 5 absorbs reflected power from the coaxial line to keep power source stable.
  • the microwave power of the coaxial TEM mode is most suitable for concentrating high frequency power on the inner conductor and dissipating it mostly therein.
  • the TEM mode is also stable against mechanical vibrations of the running wire
  • the heating apparatus shown in FIG. 3 is provided with an electric heater 2t] wound on the outer conductor 2.
  • the heater is embedded in a heat insulating material 21 such as asbestos and covered with a protecting metal tube 22.
  • the wire 1 may be heated up not only by ohmic loss and dielectric loss but by radiation heat supplied from the surrounding electric heater 20.
  • Such a structure of heating apparatus especially when utilized for the foaming process in the manufacture of foamed synthetic resin insulated electric wires, as described later, permits high speed production of foamed plastic insulated wires of good quality.
  • a resonator is formed in the apparatus by shorting the inner and outer conductors at both ends of the above high loss transmission line. This helps reduce the overall size of the heating apparatus. Since the wire 1 must be kept noncontact with any part in an exciting section and other sections in the whole apparatus, noncontact short elements and a noncontact exciting section must be provided to make such a coaxial resonator.
  • the noncontact short elements may be constructed by utilizing the effect of detuned short of a cavity resonator, which is a tunable waveguide cavity provided with a couple of tubes to permit the wire to run through as shown in FIG. 7.
  • the coaxial line-waveguide transducer may be used as shown in FIG. 2, where the movable shorting plunger serves not only to adjust the coupling with a cavity but to adjust the resonant frequency without changing the length of the coaxial cavity.
  • FIG. 6 Such a heating apparatus of resonator type is illustrated in FIG. 6. Near the ends of the coaxial line 2, there are mounted noncontact short elements 8 and 8'.
  • the short element 8 and b are each composed of 1) two waveguide members 81 and 82 connected transversely to the outer conductor 2 of the coaxial line, (2) a metallic plate 83 for shorting the free end of the waveguide member 32, and (3) a movable shorting plate M with an adjustment screw 85 mounted to the free end of the waveguide 81.
  • the noncontact short element 8 and i3 serve as a cavity filter.
  • FIG. 8a shows an example of the short characteristic of noncontact short elements 8 and 8, ascertained by the use of a measuring circuit shown in FIG. 8b.
  • FIG. 8a shows an example of the short characteristic of noncontact short elements 8 and 8, ascertained by the use of a measuring circuit shown in FIG. 8b.
  • the abscissa represents the frequency applied and the ordinate represents the ratio of output to input levelJAs'the short element shown in FIG. 8b, a rectangular waveguide having inner dimensions 34.0 mm. X 72.1 mm. was used while the input and output lines 45 and 45 were each composed of a coaxial line having an inner conductor of 16.9 mm. and an outer conductor of 38.8 mm. in diameter.
  • the reference numeral 47 designates a high frequency oscillator and 47 an output level detector line 45.
  • the input and output line 45 were matched with the oscillator 46 and the detector 47 respectively
  • the short element in FIG. 8b has the shorting effect at the frequencies of 2,456 and 2,493 MHz.
  • the shorting frequency may be changed by means of the movable shorting plate 84 in a desired manner.
  • the shorting frequency must agree with the frequency of the high frequency power source.
  • the reference numerals 9 and 9' in FIG. 6 designate each a monitor for power leakage from the coaxial resonator, in which a loop of suitable form or a probe is inserted.
  • the lossy circuit used in one embodiment of the invention consists of a noncontact coupler 103, an isolator 105, and a waveguide transducer 106 as shown in FIG. 9.
  • the improvement of Q is evident from the graph in FIG. 10, in which the abscissa represents the frequency applied while the ordinate represents the input voltage standing wave ratio to the coaxial cavity.
  • a high loss transmission line and a resonator of a coaxial line Such a high loss transmission line or a resonator may naturally be made of a strip line or a slab line.
  • the present invention is used as the foaming furnace 17, the 5 5.
  • the insulation layer is well foamed near the conductor so coated layer is not only heated by dielectric loss that develops that the electric property thereof is improved. (In case of in the layer itself but heated from inside by the resistance loss equal foaming degree, the equivalent permittivity of the of the conductor wire. Additional heat is given from outside to insulation layer well foamed near the conductor is smaller the coated layer when the heating apparatus as shown in FIG. than otherwise.)
  • tion may be applied to heating of a metal wire without insula-
  • the high frequency heating apparatus shown in tion for example, to continuous annealing of a bare copper FIGS. 1, 3, and 6 are given such construction as de rib d i wire.
  • Examples of continuous annealing of a bare copper wire examples I, 2, and 3, the foamed synthetic resin insulated will be described in the following electric wires produced by them have the characteristics as shown in the columns of examples 1, 2, and 3 of table 1.
  • EXAMPLE 4 An annealing furnace using a high loss coaxial line as shown EXAMPLE 1 in FIG. 1 was employed. The outer conductor of the coaxial line was 53.5;mm. in inner diameter and 3.6 m. in length.
  • the outer conductor of the coaxial line was 53.5;mm. in inner diameter and 3.6 m. in length.
  • the outer conductor of the coaxial line was cpaxlal me was a rectangular waveguide havmg mner dlmen' 53.5 mm. in inner diameter and 6.6 mm. in length.
  • X721 1 used a magneFrQ havmgra 2,450
  • a hard copper wire was 0.4 mm. in diameter. mm. was employed as the waveguide system for feeding high I frequency power to the coaxial line.
  • the high frequency EXAMPLE 5 power source was a magnetron having a power of 1.2 kw. at 2,450 MHz.
  • the conductor wire was a soft copper wire of 0.32
  • An annealmg furnace a coaxial resonator as shown I" P mm in diameter
  • a coating Solution was made of one part by FIG. 6 was used.
  • the outer conductor thereof was 53.5 mm. in weight of high density polyethylene (density: 0949, melt diameter and 2 m. In length.
  • the short element was a rectandex: 0.32) mixed with two parts by weight of xylene as a solgular Wavegude ,havmg mner dlmenslens X vent.
  • the solution at 130 C. was coated on the copper wire.
  • 35 other eondmens were the m as m example
  • the results obtained are shown in table 2.
  • EXAMPLE 2 A heating furnace using a high loss coaxial line and a con TABLE 2 nectional heater as shown in FIG. 3 was used.
  • Example 5 ductor of the coaxial line was 5 3.5 mm. in inner diameter and Sample Number 1 2 3 1 2 3 3.3 m. in length.
  • the heater having a power of 10 kw.
  • FIG. 6 was used.
  • the outer conductor thereof was 53.5 mm. in Further changes also may be made without departing the inner diameter and 2 m. in length.
  • the short element was a scope and spirit of the invention as set forth in the appended rectangular waveguide having inner dimensions 34.0 mm.
  • X claims.- 72.1 mm. Other conditions were the same as in example 1.
  • the insulation layer is uniformly foamed and well cured so that the amount of residual solvent may be reduced. 2. Because the optimum foaming condition can easily be obtained, the foaming degree is remarkably improved. 3.
  • the insulation layer, which is well cured, has excellent mechanical properties, that is, a good elongation and a 4. a waveguide system for coupling said coaxial line and said power source with each other in noncontacting relationship to said inner conductor, said coaxial line and said shorting elements together constituting a high frequency coaxial resonator, said coaxial resonator being immersed in a dielectric liquid.
  • a noncontact coaxial resonator type high frequency heating apparatus for heating a running metal wire comprising:
  • a high frequency coaxial transmission line immersed in a dielectric liquid wherein said running wire to be heated serves as an inner conductor and a tubular outer conductor;
  • detuned cavity resonator elements for short circuiting said wire and said outer conductor in a noncontacting relationship to each other near the ends of said outer conductor;
  • a bare copper wire, an enameled wire, or a synthetic resin-coated wire is used as an inner conductor.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
US810650A 1968-04-03 1969-03-26 High frequency heating apparatus Expired - Lifetime US3571551A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2146568 1968-04-03
JP8309268 1968-11-13
JP472269A JPS4837295B1 (enrdf_load_html_response) 1969-01-24 1969-01-24

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US3571551A true US3571551A (en) 1971-03-23

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US (1) US3571551A (enrdf_load_html_response)
DE (1) DE1916870A1 (enrdf_load_html_response)
FR (1) FR2005474A1 (enrdf_load_html_response)
GB (1) GB1247404A (enrdf_load_html_response)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761665A (en) * 1972-05-25 1973-09-25 Tokyo Shibaura Electric Co Microwave heating apparatus with looped wave guide and phase shifting means
US3872278A (en) * 1971-09-30 1975-03-18 Celanese Corp Method for heat treatment of substrates
US4144434A (en) * 1976-06-14 1979-03-13 Societe Lignes Telegraphiques Et Telephoniques Microwave heating devices
US4780585A (en) * 1985-06-28 1988-10-25 Societe Nationale Elf Aquitaine Method and device for the thermal treatment of a conductor element at least partially constituted by a conducting material
EP3210439A4 (en) * 2014-10-23 2018-07-11 Harold Dail Kimrey Jr Radio frequency heating system
US11006656B2 (en) 2017-10-19 2021-05-18 Harold Dail Kimrey, JR. High intensity radio frequency heating of packaged articles
US20230264538A1 (en) * 2022-02-18 2023-08-24 Zero Electric Vehicles Corp. High efficiency heating system for electric vehicle

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2422530C3 (de) * 1974-05-09 1980-10-16 Bach, Hannelore Wilhelmine Else, 8032 Graefelfing Verfahren zur Konservierung von wasser- und/oder eiweißhaltigen homogenen Lebensmitteln
AU6093480A (en) * 1979-10-04 1981-04-09 Schenectady Chemicals Inc. Microwave curing of resins
GB2136315B (en) * 1983-02-04 1986-06-11 Standard Telephones Cables Ltd Insulating coatings
FR2552613A1 (fr) * 1983-09-28 1985-03-29 Thourel Leo Dispositif de chauffage par micro-ondes
FR2683420B1 (fr) * 1991-11-05 1996-07-12 Bordeaux 1 Universite Dispositif pour l'application de micro-ondes en vue du traitement d'un materiau.

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3102181A (en) * 1959-05-01 1963-08-27 Philips Corp High-frequency heating furnaces operating with very high frequencies
CA703049A (en) * 1965-02-02 The British Iron And Steel Research Association Continuous heat treatment of elongate metal material
US3235702A (en) * 1962-10-26 1966-02-15 Philips Corp High-frequency oven
FR1452124A (fr) * 1965-07-05 1966-02-25 Sachsische Glasfaser Ind Wagne Procédé d'échauffement, notamment de substances diélectriques sous l'effet d'un champ haute fréquence
US3452176A (en) * 1967-05-24 1969-06-24 Melvin L Levinson Heating a moving conductor by electromagnetic wave irradiation in the microwave region
US3457385A (en) * 1966-07-07 1969-07-22 Canadian Patents Dev Apparatus for dielectric heating
US3461261A (en) * 1966-10-31 1969-08-12 Du Pont Heating apparatus
US3465114A (en) * 1966-09-19 1969-09-02 Canadian Patents Dev Method and apparatus for dielectric heating

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA703049A (en) * 1965-02-02 The British Iron And Steel Research Association Continuous heat treatment of elongate metal material
US3102181A (en) * 1959-05-01 1963-08-27 Philips Corp High-frequency heating furnaces operating with very high frequencies
US3235702A (en) * 1962-10-26 1966-02-15 Philips Corp High-frequency oven
FR1452124A (fr) * 1965-07-05 1966-02-25 Sachsische Glasfaser Ind Wagne Procédé d'échauffement, notamment de substances diélectriques sous l'effet d'un champ haute fréquence
US3457385A (en) * 1966-07-07 1969-07-22 Canadian Patents Dev Apparatus for dielectric heating
US3465114A (en) * 1966-09-19 1969-09-02 Canadian Patents Dev Method and apparatus for dielectric heating
US3461261A (en) * 1966-10-31 1969-08-12 Du Pont Heating apparatus
US3452176A (en) * 1967-05-24 1969-06-24 Melvin L Levinson Heating a moving conductor by electromagnetic wave irradiation in the microwave region

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872278A (en) * 1971-09-30 1975-03-18 Celanese Corp Method for heat treatment of substrates
US3761665A (en) * 1972-05-25 1973-09-25 Tokyo Shibaura Electric Co Microwave heating apparatus with looped wave guide and phase shifting means
US4144434A (en) * 1976-06-14 1979-03-13 Societe Lignes Telegraphiques Et Telephoniques Microwave heating devices
US4780585A (en) * 1985-06-28 1988-10-25 Societe Nationale Elf Aquitaine Method and device for the thermal treatment of a conductor element at least partially constituted by a conducting material
EP3210439A4 (en) * 2014-10-23 2018-07-11 Harold Dail Kimrey Jr Radio frequency heating system
US10314121B2 (en) 2014-10-23 2019-06-04 Harold Dail Kimrey, JR. Radio frequency heating system
EP3554192A1 (en) * 2014-10-23 2019-10-16 Harold Dail Kimrey Jr Radio frequency heating system
AU2015335674B2 (en) * 2014-10-23 2020-12-17 Harold Dail Kimrey Jr. Radio frequency heating system
US12273984B2 (en) 2014-10-23 2025-04-08 Harold Dail Kimrey, JR. Radio frequency heating system
US11412586B2 (en) 2014-10-23 2022-08-09 Harold Dail Kimrey, JR. Radio frequency heating system
US11044927B2 (en) 2017-10-19 2021-06-29 Harold Dail Kimrey, JR. Energy absorptive components for radio frequency heating of packaged articles
US11129398B2 (en) 2017-10-19 2021-09-28 Harold Dail Kimrey, JR. Radio frequency heating process with residence time control of packaged articles
US11166480B2 (en) 2017-10-19 2021-11-09 Harold Dail Kimrey, JR. Conveyance of packaged articles heated with radio frequency energy
US11039631B2 (en) 2017-10-19 2021-06-22 Harold Dail Kimrey, JR. Compact radio frequency heating of packaged articles
US11445739B2 (en) 2017-10-19 2022-09-20 Harold Dail Kimrey, JR. Contact members for packaged articles heated with radio frequency energy
US11612177B2 (en) 2017-10-19 2023-03-28 Harold Dail Kimrey, JR. Application of radio frequency energy to packaged articles
US11856976B2 (en) 2017-10-19 2024-01-02 Harold Dail Kimrey, JR. Contact members for packaged articles heated with radio frequency energy
US12035734B2 (en) 2017-10-19 2024-07-16 Harold Dail Kimrey, JR. High intensity radio frequency heating of packaged articles
US11006656B2 (en) 2017-10-19 2021-05-18 Harold Dail Kimrey, JR. High intensity radio frequency heating of packaged articles
US12295378B2 (en) 2017-10-19 2025-05-13 Harold Dail Kimrey, JR. Contact members for packaged articles heated with radio frequency energy
US20230264538A1 (en) * 2022-02-18 2023-08-24 Zero Electric Vehicles Corp. High efficiency heating system for electric vehicle

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Publication number Publication date
GB1247404A (en) 1971-09-22
DE1916870B2 (enrdf_load_html_response) 1970-12-03
FR2005474A1 (enrdf_load_html_response) 1969-12-12
DE1916870A1 (de) 1969-10-09

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