US3304399A - High-frequency furnace for high-frequency heating by means of ultra-high frequencies - Google Patents

High-frequency furnace for high-frequency heating by means of ultra-high frequencies Download PDF

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Publication number
US3304399A
US3304399A US350698A US35069864A US3304399A US 3304399 A US3304399 A US 3304399A US 350698 A US350698 A US 350698A US 35069864 A US35069864 A US 35069864A US 3304399 A US3304399 A US 3304399A
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frequency
heating
waveguide
waveguide systems
heating units
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Expired - Lifetime
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US350698A
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English (en)
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Timmerma Franciscus Hendricus
Helm Johan Posthuma Van Der
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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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

Definitions

  • the invention relates to dielectric heating devices which utilize ultra-high frequency energy. More particularly, to a high-frequency furnace provided with several ultra-high frequency generators wherein the ultrahigh frequency oscillations of each of the ultra-high frequency generators are applied to one of several folded waveguide systems arranged in sequence.
  • Each waveguide system comprises a plurality of adjacent lengths of waveguide, while a channel is provided in all the waveguide systems through which the object to be heated is passed through the various waveguide systems in sequence in a direction at right angles to the walls of the adjacent lengths of waveguide, which for this purpose are each provided with an aperture of passage.
  • the high-frequency furnace according to the invention may be used to particular advantage for drying foils, tows of filaments, and the like.
  • the high-frequency furnace according to the invention is characterized in that ultra-high frequency oscillations from each of the various ultra-high frequency generators are applied to the associated waveguide system through an additional folded waveguide system, which also comprises a plurality of adjacent lengths of waveguide provided with apertures in their walls for guiding the object to be heated in a direction at right angles to these walls.
  • an additional folded waveguide system which also comprises a plurality of adjacent lengths of waveguide provided with apertures in their walls for guiding the object to be heated in a direction at right angles to these walls.
  • all the said additional waveguide systems are disposed so as to succeed the first-mentioned waveguide systems.
  • the single figure of the drawing shows a perspective view of a high-frequency furnace according to the invention, which is designed for drying a tow of filaments l, which enters the high-frequency furnace with a degree of humidity, measured in percent by weight, of about 300%, and this degree of humidity is to be reduced to, for example, exactly 12% by high-frequency heating in thehigh-frequency furnace.
  • the high-frequency furnace comprises three magnetron generators 2, 3, 4 of 2 kw. each for generating oscillations at a frequency of, for example, 2450 mc./s.
  • the ultra-high frequency oscillations of each of the magnetron-generators 2, 3, 4 are applied through wave-guides 5, 6, 7 to individual ones of three folded waveguide systems 8, 9, 10 arranged in sequence.
  • the outer wall of the waveguide system 10 is partially broken away to show that the folded waveguide system 10, which is contained in a box, is in the form of a plurality of adjacent lengths of waveguide which are joined to one another, each pair of adjoining lengths being separated from one another by a common boundary wall.
  • Ultra-high frequency oscillations of the TE mode are fed into the folded waveguide systems 8, 9, 10 through the waveguides 5, 6, 7 and propagate in the folded waveguide systems 8, 9, 10 in a manner such that the direction of polarisation of the electric field vector is at right angles to the common boundary walls.
  • a channel 11 is provided in each of the folded waveguide systems 8, 9, 10 in a direction at right angles to the boundary walls of the adjoining lengths of waveguide, each wall being provided with a slit-shaped aperture of passage.
  • the tow of filaments to be dried passes successively through the waveguide systems 8, 9, 10 fed by the magnetron generators 4, 3, 2.
  • Short-circuit plungers 12, 13, 14 are arranged in the wave-guides 5, 6, 7 to provide load-matching for the magnetron generators 2, 3, 4.
  • the tow of filaments 1 to be dried is thus led through the folded waveguide systems 8, 9, 10 in sequence, in each of said folded waveguide systems 8, 9, 10 the ultrahigh frequency oscillations of the TE mode are guided along the tow 1 in the successive lengths of waveguide so that the tow 1 is dried by the dielectric heating produced.
  • the tow 1 when passing through the folded waveguide systems 8, 9, 10 absorbs a power which is proportional to the squareof the electric field strength and to the value of the instantaneous load.
  • the length of the highfrequency furnace is reduced and at the same time the heating efiiciency is improved by applying the ultra-high frequency'oscillations produced by the various magnetron generators 2, 3, 4 to the associated wave guide systems 10, 9, 8 through additional folded wave guide systems 15, 16, 17.
  • Each of the latter wave guide systems also comprise a plurality of adjacent lengths of waveguide provided with apertures in their walls which form a channel 11 for guiding the object to be heated in a direction at right angles to the walls of the waveguides.
  • the said additional waveguide systems 15, 16, 17 are arranged so as to succeed the firstmentioned waveguide systems 8, 9, 10.
  • the outer wall of the additional waveguide system 15 is partly broken away so as to show that this system, similarly to the waveguide system 10, comprises a plurality of lengths of waveguide joined to one another,
  • the degree of humidity of the tow of filaments 1 is considerably reduced by the high-frequency heating in the folded waveguide systems 8, 9, 10, after which this tow 1 is passed through the additional waveguide systems 15, 16, 17 for further reduction of the degree of humidity to the desired value.
  • the degree of humidity of the tow 1 after passing through the folded waveguide systems 8, 9, may be and is to be reduced to the desired value of 12% in the additional wave-guide systems 15, 16. 17.
  • the load imposed on the waveguide systems 15, 16, 17 is considerably decreased owing to the reduction in the degree of humidity of the tow 1.
  • high-frequency heating is effected at the maximum field strength of the high-frequency oscillations due to their direct connection to the magnetron generators 2, 3, 4, and this maximum field strength is substantially maintained in the folded waveguide systems 15, 16, 17 owing to the slight dissipative power of the small load imposed by the tow 1 having a low degree of humidity.
  • the efficiency of the magnetron generators 2, 3, 4 is particularly high because of the fact that the high-frequency oscillations after passing through the folded waveguide systems 15, 16, 17 are applied, through the waveguides 5, 6, 7, to the first-mentioned folded waveguide systems 8, 9, 11) for the magnetron generators 2, 3, 4 are each connected to one of the folded wave guide systems 15, 16, 17 and to one of the folded Waveguide systems 8, 9, 10, which represent a light load and a heavy load respectively, so that the overall loading of each of the magnetrons is favourable.
  • the matching plungers 12, 13, 14 permit an optimum power transfer from the magnetron generators 2, 3, 4 to the tow of filaments 1.
  • the length of the high-frequency furnace is reduced while its heating efficiency is increased, and furthermore an effective drying process is achieved.
  • the high-frequency furnace described provides the important practical effect of remarkable uniformity of the drying process. If, for ex- :ample, the tow of filaments 1 before passing through the waveguide systems 15, 16, 17 shows differences in degree of humidity along its width, at the area of the highest degree of humidity of the said tow 1 due to the increase in the load at this area the power absorbed at this area and hence the drying effect will greatly increase, since the absorbed power is proportional to the value of the load and to the square of the electric field strength, which has a maximum value in the waveguide systems 15, 16, 17.
  • the folded waveguide systems 15, 16, 17 provide a highly equalising effect with respect to differences in degree of humidity and it has been found, for example, that the difference in degree of humidity of the tow 1 after passing through the high-frequency furnace are less than a few tenths of a percent.
  • a tow of filaments 1 having a length of 3 kms. and a width of 50 cms. was treated per hour to reduce the degree of humidity from 300% to 12%.
  • the efii-ciency of the furnace was The structure of the high-frequency furnace, in which high-frequency heating is performed at a maximum field strength with a low degree of humidity of the tow of filaments in the folded waveguide systems 15, 16, 17 and in which the ultra-high frequency oscillations taken from the waveguide systems 15, 16, 17 are used for high-frequency heating of the tow with a comparatively high degree of humidity in the folded waveguide systems 8, 9, 10, permits of further reducing the size of the high-frequency furnace, which is effected by reducing the spacings between the boundary walls of the lengths of waveguide in the waveguide systems 8, 9, 10.
  • High-frequency heating apparatus comprising first and second groups of heating units sequentially arranged in the path of an object to be heated, each of said heating units comprising a waveguide structure having a plurality of spaced partition members extending transversely to said path and arranged to form a plurality of adjacent waveguide sections interconnected to define a serpentine path for high-frequency energy, each of said partition members having an aperture therein to form a channel for the passage of said object, a plurality of high-frequency generators coupled to individual ones of the heating units of said first group, and means for coupling the heating units of said first group to individual ones of the heating units of said second group thereby forming a high-frequency energy propagation path for each generator com prising a heating unit of each of said first and second groups.
  • partition members of said heating unit comprise parallel walls having aligned apertures therein arranged to allow said object to pass through said waveguide structures in sequence in a direction at right angles to the walls of the adjacent waveguide sections.
  • High-frequency heating apparatus comprising first and second equal groups of heating units sequentially arranged in the path of an object to be heated, all of the heating units of said second group being arranged ahead of the heating units of said first group so that said object passes through said second group of heating units before it passes through said first group of heating units, each of said heating units comprising a waveguide structure having a plurality of parallel spaced partition members extending transversely to said path and arranged to form a plurality of adjacent waveguide sections interconnected to define a serpentine path for high-frequency energy, said partition members having aligned apertures therein for passage of said object, a plurality of high-frequency generators equal to the number of heating units of said first group, means for coupling each of said generators to an individual one of the heating units of said first group, and energy coupling means interconnecting the References Cited by the Examiner UNITED STATES PATENTS 2,521,993 9/1950 Parker 219-1055 2,640,142 5/1953 Kinn 219-10.55 3,027,442

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Drying Of Solid Materials (AREA)
US350698A 1963-03-11 1964-03-10 High-frequency furnace for high-frequency heating by means of ultra-high frequencies Expired - Lifetime US3304399A (en)

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NL290076 1963-03-11

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US3304399A true US3304399A (en) 1967-02-14

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US (1) US3304399A (da)
AT (1) AT241637B (da)
BE (1) BE644931A (da)
CH (1) CH415896A (da)
DE (1) DE1515067C3 (da)
DK (1) DK106104C (da)
ES (1) ES297396A1 (da)
GB (1) GB1051091A (da)
NL (1) NL290076A (da)
SE (1) SE305496B (da)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3413433A (en) * 1965-03-27 1968-11-26 Philips Corp High-frequency heating devices comprising a waveguide for heating thin widths of material
US3470343A (en) * 1966-09-13 1969-09-30 Rank Organisation Ltd Heat treatment of sheet and web materials
US3471672A (en) * 1967-04-28 1969-10-07 Varian Associates Slotted waveguide applicator
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus
US3506467A (en) * 1966-12-12 1970-04-14 Francis S Ulrich Applying a protective film to unset printing ink on backing material
US3622733A (en) * 1970-01-28 1971-11-23 Cryodry Corp Method and apparatus for drying sheet materials
US3666905A (en) * 1969-04-25 1972-05-30 Messrs Paul Troester Maschinen Method and apparatus for dielectric heating
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US5217656A (en) * 1990-07-12 1993-06-08 The C. A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members
US5866060A (en) * 1989-12-06 1999-02-02 C. A. Lawton Company Method for making preforms

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4446348A (en) * 1982-03-29 1984-05-01 E. I. Du Pont De Nemours And Company Serpentine microwave applicator

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE629047A (da) *
US2521993A (en) * 1948-04-30 1950-09-12 Rca Corp Radio-frequency heating electrode for filamentary material
US2640142A (en) * 1946-10-04 1953-05-26 Westinghouse Electric Corp Microwave heating
US3027442A (en) * 1960-02-29 1962-03-27 Philips Corp High-frequency furnaces
FR1370675A (fr) * 1963-06-26 1964-08-28 Chausson Usines Sa Four à ondes d'hyperfréquence, notamment pour la cuisson de feuilles ou plaques en matière synthétique et applications analogues
GB982171A (en) * 1962-10-26 1965-02-03 Philips Electronic Associated Improvements in or relating to high-frequency ovens

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE629047A (da) *
US2640142A (en) * 1946-10-04 1953-05-26 Westinghouse Electric Corp Microwave heating
US2521993A (en) * 1948-04-30 1950-09-12 Rca Corp Radio-frequency heating electrode for filamentary material
US3027442A (en) * 1960-02-29 1962-03-27 Philips Corp High-frequency furnaces
GB982171A (en) * 1962-10-26 1965-02-03 Philips Electronic Associated Improvements in or relating to high-frequency ovens
FR1370675A (fr) * 1963-06-26 1964-08-28 Chausson Usines Sa Four à ondes d'hyperfréquence, notamment pour la cuisson de feuilles ou plaques en matière synthétique et applications analogues

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3413433A (en) * 1965-03-27 1968-11-26 Philips Corp High-frequency heating devices comprising a waveguide for heating thin widths of material
US3470343A (en) * 1966-09-13 1969-09-30 Rank Organisation Ltd Heat treatment of sheet and web materials
US3506467A (en) * 1966-12-12 1970-04-14 Francis S Ulrich Applying a protective film to unset printing ink on backing material
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus
US3471672A (en) * 1967-04-28 1969-10-07 Varian Associates Slotted waveguide applicator
US3666905A (en) * 1969-04-25 1972-05-30 Messrs Paul Troester Maschinen Method and apparatus for dielectric heating
US3622733A (en) * 1970-01-28 1971-11-23 Cryodry Corp Method and apparatus for drying sheet materials
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US5866060A (en) * 1989-12-06 1999-02-02 C. A. Lawton Company Method for making preforms
US6001300A (en) * 1989-12-06 1999-12-14 C.A. Lawton Company Method for making rigid three-dimensional preforms using directed electromagnetic energy
US6004123A (en) * 1989-12-06 1999-12-21 C.A. Lawton Company Apparatus for making preforms
US5217656A (en) * 1990-07-12 1993-06-08 The C. A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members
US5827392A (en) * 1990-07-12 1998-10-27 C.A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members

Also Published As

Publication number Publication date
BE644931A (da) 1964-09-09
DE1515067C3 (de) 1973-12-13
DK106104C (da) 1966-12-19
DE1515067A1 (de) 1969-06-26
ES297396A1 (es) 1964-09-01
SE305496B (da) 1968-10-28
GB1051091A (da)
NL290076A (da)
CH415896A (de) 1966-06-30
DE1515067B2 (de) 1973-05-30
AT241637B (de) 1965-08-10

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