US3666905A - Method and apparatus for dielectric heating - Google Patents

Method and apparatus for dielectric heating Download PDF

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Publication number
US3666905A
US3666905A US31603A US3666905DA US3666905A US 3666905 A US3666905 A US 3666905A US 31603 A US31603 A US 31603A US 3666905D A US3666905D A US 3666905DA US 3666905 A US3666905 A US 3666905A
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United States
Prior art keywords
waveguide
microwave energy
waveguides
flows
articles
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Expired - Lifetime
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US31603A
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English (en)
Inventor
Paul C Muller
Karl H Schneider
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Paul Troester MaschinenfabriK
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Paul Troester MaschinenfabriK
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B29B13/02—Conditioning or physical treatment of the material to be shaped by heating
    • B29B13/023—Half-products, e.g. films, plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
    • B29C35/10—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation for articles of indefinite length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
    • B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
    • B29C2035/0855—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using microwave
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/04—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould using liquids, gas or steam
    • B29C35/045—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould using liquids, gas or steam using gas or flames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/001—Profiled members, e.g. beams, sections
    • B29L2031/003—Profiled members, e.g. beams, sections having a profiled transverse cross-section

Definitions

  • Sheets-Sheet 8 METHOD AND APPARATUS FOR DIELECTRIC HEATING This invention relates to methods and'apparatus for the continuous dielectric heating of articles of plastics, rubber or like materials, by the use of micro-wave energy.
  • Heating apparatus has been previously proposed in which either a rectangular cross-section hollow waveguide is used, with H -Mode excitation in the transversal direction of the objects to be heated, or else a circular section hollow waveguide is used with E-Mode excitation in the longitudinal direction of the objects. It has been found that only articles having particular preselected surface profiles can be treated with these devices in a manner ensuring satisfactory quality. Low degress of efficiency, uneven heating, with so-called snaking, i.e., with thick and thin portions alternating along the objects, are liable to occur owing to focusing of energy in the heated object are the undesirable phenomena attendant upon the operation of such devices with their high field intensities acting in one direction.
  • An object'of the present invention is to mitigate the above drawbacks and to provide for the dielectric heating of objects of complicated and/or irregular shapes, for example so that objects with irregular cross-sectional areas and/or of varying thicknesses can be heated and vulcanized or hardened rapidly and evenly withoutthe risk of local overheating.
  • a method of the continuous dielectric heating of articles of plastics, rubber or like dielectric materials by the use of microwave energy comprising exposing an article to be heated successively to at least two spaced apart flows of microwave energy acting at different angles to one another.
  • apparatus for the continuous dielectric heating of articles of plastics, rubber or like dielectric material comprising a hollow waveguide, a conveyor extending in said waveguide and adapted to move articles to be heated through said waveguide, and at least one further hollow waveguide communicating at an angle with said waveguide,
  • FIG.- 1 is a side view of a dielectric heating apparatus according to the invention
  • FIG. 2 is a cross section along the line IIII of FIG. 1, and
  • FIG. 3 is a partial illustration of a self-stressing Teflon lining inserted in the guide channel for the conveyor belt.
  • the illustrated apparatus comprises two hollow waveguides l and 2, which take sinuous course and which are made up of waveguide conductors (H -Mode) of rectangular cross section.
  • the waveguides l and 2 have substantially parallel straight portions alternating with U-shaped portions.
  • the straight portions are interconnected substantially centrally of their lengths by hollow intermediate waveguides 3 with E- Mode excitation.
  • Guides 3 may be of circular cross section, for example, and are preferably positioned perpendicularly to the straight portions of conductors land 2 so that the straight portions communicate at right angles into the composite waveguide which consists of the series of mutually aligned intermediate pieces 3 together with a central piece 4 and end pieces 5.
  • Central piece 4 is square in cross-section and serves as a resonant cavity, and end pieces 5 are constructed as wave traps.
  • a conveyor belt 6 made of Teflon is guided to run longitudinally through the composite waveguide 3, 4 and 5.
  • the conveyor belt 6 is tensioned by tensioning and driving pulleys 7 and 8.
  • Within the composite waveguide the upper run of the belt 6 is supported on rollers 9 which are adjustable in height,
  • the rollers 9 are made, for example, of ceramic or other insulating material and can be adjusted in their vertical positions in unison or individually.
  • Water loads 10 and 11 communicate, through flexible connecting tubes, with the outer ends of the two runs of hollow conductor 1 and 2 respectively, and absorb the microwave energy not absorbed until then, so that no-micro-wave emerge from the apparatus.
  • a hollow U-shaped waveguide 12, of rectangular cross section, is mounted in telescopic sliding contact to the adjacent ends of the runs of waveguides 1 and 2.
  • the relative positions of waveguide 12 on the runs ofwaveguide 1 and 2 can be adjusted bymeans of an eccentric disc 13 or by hand, with greater or smaller force.
  • a magnetron 14 which supplies microwave frequency energy (for example in the range 0.9 to 2.5 CH2) and which, via anexciter system 15 extending into the hollow conductor 12, feeds energy in the micro-wave range into the'hollow conductor l2 and thus into the entire hollow-conductor or waveguide system.
  • This magnetron 14 is preferably situated centrally of the U-shaped hollow conductor 12, but may also be situated to the right or to the left up to half the length of a wave, to enable the relative degree of excitation in the two runs of hollow conductor 1 and 2 to be controlled.
  • the resonator 4 can be brought into resonance automatically or by hand, by means of a slide 17 accommodated in a tap line 16.
  • a pipe connection 18 is connected to the tap line 16 via a grid 19 and enables hot air or a hot inert protective gas to be fed into the internal cavity 20 of the central resonator 4 in adjustable quantities and/or at an adjustable temperature.
  • This protective gas leaves the apparatus through i the opposite ends of the horizontal composite waveguide.
  • the protective gas ensures that any easily volatile and explosive substances which may form in the apparatus, for example, during the vulcanization of rubber, are rapidly evacuated therefrom, without any undesirable cooling of the objects to be treated and present therein.
  • the composite waveguideaccommodating the conveyor belt 6 is provided with a lining which consists of two opposed U-shaped channel members 21 and 22 fitting into each other and stretched by tension springs 23 over the outer edges of the hollow end conductors 5, thus surrounding the conveyor belt 6 running through the apparatus, as may be seen, in particular, from FIG. 3. This results in an approximately square section passage through which pass the objects 24 to be heated.
  • FIG. 1 indicated that in the region of the intermediate waveguides 3 lines of force pass through the objects to be heated, approximately in the transversal direction, in accordance with the arrows 25, while in the region of the runs of waveguides 1 and 2 the lines of force are oriented approximately longitudinally or the path of movement of the objects 24, in accordance with the arrows 26.
  • This alternation of the field is important for an even heating effect, particularly in the case of complex plastics or rubber surface shapes and profiles.
  • the central piece 4 which serves as a resonance chamber, lines of force are present in both directions, as implied by the arrows 27 and 28.
  • rollers 9 are positioned at different heights, so that the upper stringer of the conveyor belt 6 slants upwards or downwards as it passes through the apparatus, this may result in still more favorable operating conditions, inasmuch as different parts of the objects then move in succession into the most suitable position for treatment in each case, so that an evenly treated final product is obtained at the outlet from the apparatus.
  • the runs of waveguides 1 and 2 in each case consist of only two U-sections placed together, or take the form of one single complete S-shape train, it is also possible for a number of portions of this kind to be provided in succession to one another, so that the objects may be treated a greater number of taimes.
  • a limit is when the energy emanating-from the magnetron 14 has been completely consumed.
  • the U-shaped hollow conductor 12 serving as a branching means for the energy can be dispensed with, if more moderate performances are required, and the excitation connection can be made direct to a run of each hollow conductor 1 or 2.
  • the described apparatus has a considerable electrical band-width and that no critical oscillation conditions occur.
  • the alternate longitudinal and transverse energy flows to which an article is exposed avoid high field intensities acting constantly in one direction, which could easily cause local burning.
  • Apparatus for the continuous dielectric heating of articles of plastics, rubber or like materials comprising a hollow waveguide, conveyor means extending longitudinally within said waveguide, means for moving said conveyor within said waveguide to move articles to be heated through said waveguide, at least two further waveguides communicating at an angle with said first mentioned hollow waveguide, wherein each of said further waveguides has an end portion parallel and adjacent the end portion of the other waveguide, a relatively movable connection waveguide interconnecting said two further waveguides, said relatively mova ble waveguide being U-shaped and telescopically received on said parallel and adjacent end portions, and means for exciting said waveguides with microwave energy to provide spaced energy flows therein at an angle to one another.
  • said further waveguide is sinuous in shape and communicates and intersects with said first waveguide at two or more spaced apart locations.
  • said exciting means comprises a magnetron, and means displaceably mounting said magnetron and said movable connecting waveguide, whereby to permit adjustment in the relative excitation on the two waveguides.
  • Apparatus according to claim 1 including a resonant chamber, and means coupling said resonant chamber in said first hollow waveguide intermediate the ends thereof.
  • Apparatus according to claim 1 including a tap line communicating with said resonant chamber and means for supplying protective gas to said tap line.
  • a method for the continuous dielectric heating of articles of plastics, rubber or like material by the use of microwave energy comprising:
  • the method of claim 7 further including the steps of moving the article to be heated in a predetermined path, said spaced apart flows of energy acting respectively substantially longitudinally of said path and substantially transversely of said path.

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  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Toxicology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
US31603A 1969-04-25 1970-04-24 Method and apparatus for dielectric heating Expired - Lifetime US3666905A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691921065 DE1921065A1 (de) 1969-04-25 1969-04-25 Verfahren und Vorrichtung zum dielektrischen Erwaermen von Objekten

Publications (1)

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US3666905A true US3666905A (en) 1972-05-30

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US31603A Expired - Lifetime US3666905A (en) 1969-04-25 1970-04-24 Method and apparatus for dielectric heating

Country Status (5)

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US (1) US3666905A (enrdf_load_stackoverflow)
CH (1) CH523646A (enrdf_load_stackoverflow)
DE (1) DE1921065A1 (enrdf_load_stackoverflow)
FR (1) FR2046494A5 (enrdf_load_stackoverflow)
GB (1) GB1300626A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US3765425A (en) * 1971-09-02 1973-10-16 Brown & Williamson Tobacco Puffing of tobacco
WO1998049870A1 (en) * 1997-04-29 1998-11-05 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6246037B1 (en) 1999-08-11 2001-06-12 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6259077B1 (en) 1999-07-12 2001-07-10 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
WO2009073350A1 (en) 2007-11-29 2009-06-11 Dow Global Technologies, Inc. Method for controlling and optimizing microwave heating of plastic sheet

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2410932A1 (fr) * 1979-03-16 1979-06-29 Cim Lambda Int Sarl Applicateur de micro-ondes a variation de densite d'energie
DE3033012A1 (de) * 1980-09-02 1982-04-01 Paul Troester Maschinenfabrik, 3000 Hannover Vorrichtung fuer die trockene vernetzung von straengen aus elastomeren
DE3420280A1 (de) * 1983-05-31 1984-12-06 Kabushiki Kaisha Toshiba, Kawasaki, Kanagawa Vorrichtung zum vorwaermen von pressharz fuer eine halbleitervorrichtung
AT383775B (de) * 1985-01-17 1987-08-25 Naue & Naue Ges M B H Und Co Vorrichtung zur herstellung von formkoerpern
DE4024070A1 (de) * 1990-07-28 1992-01-30 Krauss Maffei Ag Einrichtung zum plastifizieren von thermoplastischen kunststoffen
CN114646202B (zh) * 2022-03-17 2023-03-24 佛山市盟思拉伸机械有限公司 薄膜生产线烘箱及其柔送风热交换单元

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3177333A (en) * 1962-08-02 1965-04-06 Tappan Co Conveyor microwave oven
US3304399A (en) * 1963-03-11 1967-02-14 Philips Corp High-frequency furnace for high-frequency heating by means of ultra-high frequencies
US3402277A (en) * 1965-10-25 1968-09-17 Patelhold Patentverwertung Microwave treating device
US3478900A (en) * 1966-11-28 1969-11-18 Cryodry Corp Apparatus for treating food products and the like with microwave energy
US3491457A (en) * 1967-10-10 1970-01-27 Bechtel Int Corp Microwave drying method and apparatus
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3177333A (en) * 1962-08-02 1965-04-06 Tappan Co Conveyor microwave oven
US3304399A (en) * 1963-03-11 1967-02-14 Philips Corp High-frequency furnace for high-frequency heating by means of ultra-high frequencies
US3402277A (en) * 1965-10-25 1968-09-17 Patelhold Patentverwertung Microwave treating device
US3478900A (en) * 1966-11-28 1969-11-18 Cryodry Corp Apparatus for treating food products and the like with microwave energy
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus
US3491457A (en) * 1967-10-10 1970-01-27 Bechtel Int Corp Microwave drying method and apparatus

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US3765425A (en) * 1971-09-02 1973-10-16 Brown & Williamson Tobacco Puffing of tobacco
WO1998049870A1 (en) * 1997-04-29 1998-11-05 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US5958275A (en) * 1997-04-29 1999-09-28 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6075232A (en) * 1997-04-29 2000-06-13 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6259077B1 (en) 1999-07-12 2001-07-10 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6590191B2 (en) 1999-07-12 2003-07-08 Industrial Microwaves Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6246037B1 (en) 1999-08-11 2001-06-12 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
US6396034B2 (en) 1999-08-11 2002-05-28 Industrial Microwave Systems, Inc. Method and apparatus for electromagnetic exposure of planar or other materials
WO2009073350A1 (en) 2007-11-29 2009-06-11 Dow Global Technologies, Inc. Method for controlling and optimizing microwave heating of plastic sheet
US20100282741A1 (en) * 2007-11-29 2010-11-11 Dow Global Technologies Inc. Method for controlling and optimizing microwave heating of plastic sheet
CN101970197A (zh) * 2007-11-29 2011-02-09 陶氏环球技术公司 控制并优化塑料板材微波加热的方法
JP2011505276A (ja) * 2007-11-29 2011-02-24 ダウ グローバル テクノロジーズ インコーポレイティド プラスチックシートのマイクロ波加熱を制御及び最適化するための方法

Also Published As

Publication number Publication date
FR2046494A5 (enrdf_load_stackoverflow) 1971-03-05
GB1300626A (en) 1972-12-20
DE1921065A1 (de) 1970-11-12
CH523646A (de) 1972-05-31

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