GB1583454A - Apparatus for continuous dielectric heating by means of microwave energy - Google Patents

Apparatus for continuous dielectric heating by means of microwave energy Download PDF

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Publication number
GB1583454A
GB1583454A GB38380/77A GB3838077A GB1583454A GB 1583454 A GB1583454 A GB 1583454A GB 38380/77 A GB38380/77 A GB 38380/77A GB 3838077 A GB3838077 A GB 3838077A GB 1583454 A GB1583454 A GB 1583454A
Authority
GB
United Kingdom
Prior art keywords
waveguide
guide sleeve
treatment chamber
rod
energy supply
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
Application number
GB38380/77A
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.)
KraussMaffei Extrusion GmbH
Original Assignee
Hermann Berstorff Maschinenbau GmbH
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 Hermann Berstorff Maschinenbau GmbH filed Critical Hermann Berstorff Maschinenbau GmbH
Publication of GB1583454A publication Critical patent/GB1583454A/en
Expired legal-status Critical Current

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Classifications

    • 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
    • H05B6/70—Feed lines
    • H05B6/705—Feed lines using microwave tuning
    • 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
    • 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
    • H05B6/70—Feed lines
    • H05B6/707—Feed lines using waveguides
    • 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
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/06—Rod-shaped

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Thermal Sciences (AREA)
  • Constitution Of High-Frequency Heating (AREA)

Description

(54) APPARATUS FOR CONTINUOUS DIELECTRIC HEATING BY MEANS OF MICROWAVE ENERGY (71) We, HERMANN BERSTORFF MASCHINENBAU GmbH, a body corpo rate organised and existing under the laws of the Federal Republic of Germany, of 3, Hannover Kleefeld, An der Breiten Wiese 3/5, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the fol lowing statement: The invention relates to apparatus for con tinuous dielectric heating by means of mic rowave energy.
Such apparatus may have a treatment chamber, particularly a treatment chamber constructed as a tunnel oven, for the con tinuous dielectric heating rod-shaped mater vial. particularly made from synthetic plastics or rubber.
The microwave generator. an energy sup ply waveguide. the treatment chamber and the load in most cases exhibit different impe dances in microwave systems. If the impe dances of the microwave generator. the energy supply waveguide and the treatment chamber on the one hand and the impedance of the load on the other are different. then it is necessary to incorporate between the two a matching transformer. the purpose of which matching transformer is to adapt the impe dance of the load to the impedance of the microwave generator, the energy supply waveguide and the treatment chamber.
Optimum utilisation of energy is guaranteed only if all the energy generated in the mic rowave generator is converted into heat in the load. This means that there must be no reflections from the load.
In order to ensure low-reflection from the load. it would be possible to so dispose one or a plurality of tuning rods or tuning screws that they are displaceable and can protrude into the energy supply waveguide. With such a tuning element or elements which acts or act as a matching transformer, it is in theory possible to adapt any desired load impedance to any desired generator impedance.
In the event of quite substantial differences in impedances of microwave generator and load, high reactive powers occur between the matching transformer and load and act on the waveguide, and can represent many times the effective power. The excessively high field strength values which occur as a result of the high reactive powers, in the gap between a tuning rod and a rod guide bore or between a tuning screw and a threaded aperture in which it is mounted, produce arc discharges which lead to erosion and thus to gradual destruction of the contact point between the tuning element and the wall of the energy supply waveguide.
According to the invention. there is provided apparatus for continuous dielectric heating by means of microwave energy comprising a treatment chamber constructed as a tunnel oven. for the continuous dielectric heating of rod-shaped material. and at least one tuning element so disposed that it can be moved and caused to protrude into an energy supply waveguide extending from a microwave generator to the treatment chamber.
wherein the tuning element is partially enclosed by a guide sleeve of length X/4. a wall of the guide sleeve. at the end thereof which is nearer. the inside of the energy supply waveguide. is in electrical contact with the tuning element and at its other end the guide sleeve is electrically conductively connected to the wall of the energy supply waveguide.
Thus ready matching between microwave generator and load can be made possible without the risk of flashover and arcing in the gap between the tuning element and its guide sleeve in the wall of the energy supply waveguide.
By providing. according to the invention.
the )V/4 length guide sleeve. the electrical contact between the tuning element and energy supply waveguide is moved to a location of minimum current flow. The danger of arcing between the tuning element and its guide sleeve is substantially diminished.
It is advantageous for the A/ 4 length guide sleeve to be disposed in a bore measuring f/2 deep. Advantageously, this ensures that the arrangement behaves electrically in the manner of a rod having good electrical contact in the plane of the energy supply waveguide. This means that adjustment of the matching transformer is possible bet ween extreme values of impedances between nil and maximum.
The apparatus of the invention can have the considerable advantage that the matching transformer is adjustable under load.
During operation of the microwave plant, the tuning elements can be continually adjusted for optimum matching of the plant without rotation or displacement of the tuning elements occasioning arc discharges in the gap between the tuning element and the guide sleeve in the wall of the energy supply waveguide.
The invention is diagrammatically illustrated by way of example in the accompanying drawings. in which: Figure 1 is a diagrammatic view of a mic rowave heating plant apparatus for continuous dielectric heating by means of microwave energy according to the invention. having a treatment chamber constructed as a tunnel oven; and Figure 2 shows a portion of the apparatus of Figure 1 on an enlarged scale.
Referring to the drawings. a rubber rod 4 extruded from an extruder 3 is fed by means of an endless conveyor belt 6. driven by a motor 5. continuously through an inlet aperturc 7 of a treatment chamber 8 which is constituted by a microwave tunnel oven of approximately square cross-section. After passing through the total length of the treatment chamber 8. the now dielectrically heated rubber rod 4 emerges through an outlet orifice 9 and is fcd to further treatment stages. e.g. conventional heating apparatus.
The microwave energy is introduced into the treatment chamber 8 at two coupling positions II and 12. The first coupling position I 1 for microwave energy is disposed onc quarter of the length of the treatment chamber cr 8 from the inlet end. A rectangular hollow waveguide 13. connected to a first microwave generator (not shown). it provided horizontally on one side of the treatmcnt chamber 8 and forms a first energy supply waveguide. The second coupling position 12 for microwave energy is located thlec-quartcrs of the length of the treatment chamber 8 from the inlet end. A hollow waveguide 14 which. like the first hollow waveguide 13, is of rectangular cross-section, and constitutes a second energy supply waveguide, is provided to extend in a direction at right-angles to the first waveguide 13 into the top of the treatment chamber 8 and links a second microwave generator 1 5 with the interior of the treatment chamber 8. By virtue of the fact that the two microwave energy supply waveguides are offset by 90" from each other, two H", waves are energised, turned through 90" with respect to each other. For different rod profiles of the material rod 4 which is to be heated, therefore, there is a favourable energy absorption angle between profile lip and electrical field line.
Disposed on the second energy supply waveguide 14 is a matching transformer 16.
In the wall 18 of the waveguide 14 which is reinforced by an external collar 17, there is a bore 19, the length of which corresponds to half the free wavelength i.e. A/2. Inserted into this bore 19 is a guide sleeve 21 of "top hat" section which has, at its end remote from the waveguide 14. a flange 22 which lies flush with the outer end of the bore 19. The guide sleeve 21 forms with the bore 19 an annular gap 23 which is one-quarter of the free wavelength in length i.e. X/4.
A displaceable tuning rod 24 protrudes through the guide sleeve 71 into the interior of the waveguide 14. The tuning rod 24 is in electrical contact with the wall 18 of the waveguide 14 via a part 25 of the guide sleeve 2 1 and the collar 17. This electrical contact part 25 is A/4 away from the bottom of the annular gap 23.
An adjusting device (not shown) engaged with a lug 26 on the tuning rod 24 can effect tuning by moving the tuning rod 24.
Fitment of the X/4 long guide sleeve 21 into the bore 19 which is A/2 long results in the arrangement behaving electrically like a rod which has good electrical contact with the inner surface of the wall 1 8 of the supply waveguide 14. It is however feasible to dispose the X/4 long guide sleeve 21 in a longer or shorter bore than the bore 1 9.
WHAT WE CLAIM IS: 1. Apparatus for continuous dielectric heating by means of microwave energy comprising a treatment chamber constructed as a tunnel oven. for the continuous dielectric heating of rod-shaped material. and at least one tuning element so disposed that it can be moved and caused to protrude into an energy supply waveguide extending from a microwave generator to the treatment chamber.
whercin the tuning element is partially enclosed by a guide sleeve of length A/4. a wall of the guide sleeve. at the end thercof which is nearer the inside of the energy supply waveguide. is in electrical contact with the tuning element and at its other end the guide sleeve is electrically conductively con
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. contact between the tuning element and energy supply waveguide is moved to a location of minimum current flow. The danger of arcing between the tuning element and its guide sleeve is substantially diminished. It is advantageous for the A/ 4 length guide sleeve to be disposed in a bore measuring f/2 deep. Advantageously, this ensures that the arrangement behaves electrically in the manner of a rod having good electrical contact in the plane of the energy supply waveguide. This means that adjustment of the matching transformer is possible bet ween extreme values of impedances between nil and maximum. The apparatus of the invention can have the considerable advantage that the matching transformer is adjustable under load. During operation of the microwave plant, the tuning elements can be continually adjusted for optimum matching of the plant without rotation or displacement of the tuning elements occasioning arc discharges in the gap between the tuning element and the guide sleeve in the wall of the energy supply waveguide. The invention is diagrammatically illustrated by way of example in the accompanying drawings. in which: Figure 1 is a diagrammatic view of a mic rowave heating plant apparatus for continuous dielectric heating by means of microwave energy according to the invention. having a treatment chamber constructed as a tunnel oven; and Figure 2 shows a portion of the apparatus of Figure 1 on an enlarged scale. Referring to the drawings. a rubber rod 4 extruded from an extruder 3 is fed by means of an endless conveyor belt 6. driven by a motor 5. continuously through an inlet aperturc 7 of a treatment chamber 8 which is constituted by a microwave tunnel oven of approximately square cross-section. After passing through the total length of the treatment chamber 8. the now dielectrically heated rubber rod 4 emerges through an outlet orifice 9 and is fcd to further treatment stages. e.g. conventional heating apparatus. The microwave energy is introduced into the treatment chamber 8 at two coupling positions II and 12. The first coupling position I 1 for microwave energy is disposed onc quarter of the length of the treatment chamber cr 8 from the inlet end. A rectangular hollow waveguide 13. connected to a first microwave generator (not shown). it provided horizontally on one side of the treatmcnt chamber 8 and forms a first energy supply waveguide. The second coupling position 12 for microwave energy is located thlec-quartcrs of the length of the treatment chamber 8 from the inlet end. A hollow waveguide 14 which. like the first hollow waveguide 13, is of rectangular cross-section, and constitutes a second energy supply waveguide, is provided to extend in a direction at right-angles to the first waveguide 13 into the top of the treatment chamber 8 and links a second microwave generator 1 5 with the interior of the treatment chamber 8. By virtue of the fact that the two microwave energy supply waveguides are offset by 90" from each other, two H", waves are energised, turned through 90" with respect to each other. For different rod profiles of the material rod 4 which is to be heated, therefore, there is a favourable energy absorption angle between profile lip and electrical field line. Disposed on the second energy supply waveguide 14 is a matching transformer 16. In the wall 18 of the waveguide 14 which is reinforced by an external collar 17, there is a bore 19, the length of which corresponds to half the free wavelength i.e. A/2. Inserted into this bore 19 is a guide sleeve 21 of "top hat" section which has, at its end remote from the waveguide 14. a flange 22 which lies flush with the outer end of the bore 19. The guide sleeve 21 forms with the bore 19 an annular gap 23 which is one-quarter of the free wavelength in length i.e. X/4. A displaceable tuning rod 24 protrudes through the guide sleeve 71 into the interior of the waveguide 14. The tuning rod 24 is in electrical contact with the wall 18 of the waveguide 14 via a part 25 of the guide sleeve 2 1 and the collar 17. This electrical contact part 25 is A/4 away from the bottom of the annular gap 23. An adjusting device (not shown) engaged with a lug 26 on the tuning rod 24 can effect tuning by moving the tuning rod 24. Fitment of the X/4 long guide sleeve 21 into the bore 19 which is A/2 long results in the arrangement behaving electrically like a rod which has good electrical contact with the inner surface of the wall 1 8 of the supply waveguide 14. It is however feasible to dispose the X/4 long guide sleeve 21 in a longer or shorter bore than the bore 1 9. WHAT WE CLAIM IS:
1. Apparatus for continuous dielectric heating by means of microwave energy comprising a treatment chamber constructed as a tunnel oven. for the continuous dielectric heating of rod-shaped material. and at least one tuning element so disposed that it can be moved and caused to protrude into an energy supply waveguide extending from a microwave generator to the treatment chamber.
whercin the tuning element is partially enclosed by a guide sleeve of length A/4. a wall of the guide sleeve. at the end thercof which is nearer the inside of the energy supply waveguide. is in electrical contact with the tuning element and at its other end the guide sleeve is electrically conductively con
nected to the wall of the energy supply waveguide.
2. Apparatus according to claim l, in which the guide sleeve of length X/4 is disposed in a bore in the wall of the energy supply waveguide, the bore being of length X/2.
3. Apparatus for continuous dielectric heating by means of microwave energy substantially as hereinbefore described and illustrated with reference to the accompanying drawings.
GB38380/77A 1976-09-21 1977-09-14 Apparatus for continuous dielectric heating by means of microwave energy Expired GB1583454A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2642336A DE2642336C2 (en) 1976-09-21 1976-09-21 Device for continuous dielectric heating by means of microwave energy

Publications (1)

Publication Number Publication Date
GB1583454A true GB1583454A (en) 1981-01-28

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ID=5988404

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Application Number Title Priority Date Filing Date
GB38380/77A Expired GB1583454A (en) 1976-09-21 1977-09-14 Apparatus for continuous dielectric heating by means of microwave energy

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DE (1) DE2642336C2 (en)
FR (1) FR2365270A1 (en)
GB (1) GB1583454A (en)
SE (1) SE424130B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE451228B (en) * 1985-12-30 1987-09-14 Stiftelsen Inst Mikrovags MICROVAGIC APPLICATOR FOR HEATING FORMATICALLY STRENGTHLY OR LONG-TERM BODIES
GB2228363A (en) * 1988-09-29 1990-08-22 English Electric Valve Co Ltd Magnetrons.

Also Published As

Publication number Publication date
FR2365270A1 (en) 1978-04-14
DE2642336B1 (en) 1978-01-26
FR2365270B3 (en) 1980-08-01
DE2642336C2 (en) 1978-09-28
SE7710546L (en) 1978-03-22
SE424130B (en) 1982-06-28

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19920914