CA1132895A - Continuously operating press - Google Patents

Continuously operating press

Info

Publication number
CA1132895A
CA1132895A CA366,298A CA366298A CA1132895A CA 1132895 A CA1132895 A CA 1132895A CA 366298 A CA366298 A CA 366298A CA 1132895 A CA1132895 A CA 1132895A
Authority
CA
Canada
Prior art keywords
press
layer
chain
metal rods
support elements
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
CA366,298A
Other languages
French (fr)
Inventor
Stefan Petersson
Sven O. Alstad
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.)
Kockums Industri AB
Original Assignee
Kockums Industri AB
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 Kockums Industri AB filed Critical Kockums Industri AB
Application granted granted Critical
Publication of CA1132895A publication Critical patent/CA1132895A/en
Expired legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B27WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27NMANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/08Moulding or pressing
    • B27N3/24Moulding or pressing characterised by using continuously acting presses having endless belts or chains moved within the compression zone
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B30PRESSES
    • B30BPRESSES IN GENERAL
    • B30B5/00Presses characterised by the use of pressing means other than those mentioned in the preceding groups
    • B30B5/04Presses characterised by the use of pressing means other than those mentioned in the preceding groups wherein the pressing means is in the form of an endless band
    • B30B5/06Presses characterised by the use of pressing means other than those mentioned in the preceding groups wherein the pressing means is in the form of an endless band co-operating with another endless band
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S198/00Conveyors: power-driven
    • Y10S198/952Heating or cooling

Abstract

A B S T R A C T

A continuously operating heat-treatment press in which a continuously advanced layer (7) of material under pressure, for example including glue-coated wood chips, is heated dielectrically. The press is of the kind which com-prises at least one endless, continuously running press chain (8), for maintaining a vertically acting press force on the layer (7) of material, said press chain (8) being formed of mutually linked support elements. The press sur-face of the support elements in the press chain (8) com-prises mutually electrically insulated metal rods (23) ex-tending in the transverse direction of the chain. At least one stationary electrode plate (28) connected to a high frequency generator is arranged adjacent said metal rods (23).

(Figure 2)

Description

Kockums Industri ~B
A continuously operating press The present invention relates to a continuously operating heat-treatment press in which a continuously advanced layer of material under pressure, for example a layer of glue-coated wood chips, is heated dielectrically, said press being of the kind which comprises an endless, continuously running press chain formed of mutually linked support elements, for maintaining a vertically acting pressure force on said material layer.
When manufacturing products made of wood chips, said products are normally hardened under pressure in a static heat-treatment press. In the manufacture of elongate wood chip products, for example the manufacture of wood beams in accordance with the ~.5. Patent Specification No.
4.112.162, it is desirable, however, to provide a con-tinuously operating heat-treatment press, in which the pro-duct is heat-treated while continuously passing through the press. When it is desired, however, to harden the product with heat produced dielectrically problems occur, since a press belt and support plates co-acting therewith must pass between the electrodes generating the dielectric heat and the layer of material. Materials which have suitable elec-trical properties in respect of said support plates, however, have a low modulus of elasticity and low mechanical strength, and hence support plates which are manufactured from such material must of necessity have a thickness which is too excessive for their acceptable function.
One attempt to solve this problem is disclosed in the German Patent Specification No. 823 632, according to which there are utilized co-running electrodes. In order to obtain reasonable heating times there is required, for example when manufacturing a beam according to said ~.S.
patent, relatively high electrical power, in the order of 300 kW. In this respect, it is suitable to use a plurality of high-frequency generators with corresponding electrodes, which electrodes must be insulated from each other, i.e.
spaced relatively great distance apart. When using co-running electrodes, which are thus stationary relative to the layer of material, one problem which arises is that the wood chips in those portions of the layer located between subsequent electrode plates are not heated to the extent required.
Consequently, a main object of the present invention is to provide a press of the kind mentioned in the introduc-tion, in which stationary electrode plates can be used while avoiding the aforementioned problems. When using stationary electrode plates, the whole of the material layer will pass each and everyone of said plates, thereby eliminating the risk of certain parts of the layer not being heated to the extent required. Each plate will contribute to heating each separate unit of length of the material layer.
This object is achieved in accordance with the in-vention in that the press surface of the support elements in the press chain has the form of mutually electrically insu-lated metal rods extending transversely of the chain, and in that at least one stationary electrode plate is arranged adjacent said metal rods and connected to a high frequency generator. Since the metal rods are insulated from each other, each of said rods will function as a dielectric elec-trode and spread the electric field over the whole width of the layer of material. The metal rods can readily be given such dimensions as to enable said rods to apply the re-quisite pressure force to the material layer.
As a result of the small width of the metal rods and the air spaces located therebetween, there is obtained over a relatively short distance a sufficiently large voltage drop to enable two electrode plates to be placed relatively close to one another without creating problems due to inter-ference. This enables the press as a whole to be kept rela-tively short and permits several generators to be used. In this way the rate of press feed and hence the capacity of the press is increased. Since the metal rods, which amony other things serve to spread the electric field, extend over the whole width of the material layer, the electrode plates located adjacent said metal rods may be divided into mutually parallel segments, for example to enable the support plates which hold the metal rods together and support said rods to pass by.
Preferably 'he metal rods in each of said support elements are held together by means of at least two vertically oriented support plates made of an insulating material and extending in the longitudinal direction of the press chain, said plates being arranged to transfer the ~ressure force to said metal rods. Suitably a continuously running press band of insulating material is arranged between the press chain and the layer of material. Further, a smoothing layer of in-sulating material may be arranged on the surface of the support elements facing said material layer thereby to pre-vent imprints of the rods being formed in the pressed product.
The invention will now be described in more detail with reference to the accompanying drawing, in which Figure l is a schematic side view of an embodiment of a heat-treatment press according to the invention, and Figure 2 is a perspective sectional view of the pressing and heat-treatment zone of the press according to Figuure l, taken on the line II-II.
The heat-treatment press illustrated in Figure l comprises an upper and a lower endless press belt l and 2, respectively, which run continuously over associated guide rollers 3, 4 and 5, 6, respectively. The belt l is made of an insulating plastics material while the belt 2 is made of Steel.
The reference 7 identifies an incoming layer of ma-terial, for example a layer of glue-coated wood chips, which ls to be heated dielectrically while being subjected to pressure in both a horizontal and a vertical direction. In the combined pressing and hardening zone, the belts 1 and 2 are supported by respective press chains 8 and 9 formed of mutually linked support elements. Each of the chains 8 and 9 passes over two rollers 10, 11 and 12, 13, respectively, of which two are driven synchronously with one another. The layer 7 is suitably taken from a pre-press, whereat means not shown are provided for retaining the dimensions of the layer of material during its travel from said pre-press to the com-bined pressin~ and heating zone in the heat-treatment press.
As will be seen from Figure 2, the support elements of the lower press chain 9 are carried on rollers 19 and are mutually linked together by means of shafts 15. For the pur-pose of retaining the lateral dimensions of the layer of ma-terial, the press is provided on each side of the press belts 1 and 2 with an array of side pressing or restraining blocks 16 which project in between the press belts. Each of the side restraining blocks 16 is connected, via a press arm 17, with a holder 18 which is provided with two runners 19 arranged to co-act with outer guide rails 20 having upper and lower c~hannel-shaped parts.
For the purpose of driving the side restraining blocks 16 synchronously with the press belts 1 and 2 and for accurately guiding the blocks in relation to said press belts, the holders 18 provided with said runners 19 are connected with horizontal shafts 21 which, via splined couplings, are displaceably mounted in holes 22 in the mutually linked sup-port plates forming the chain 9. In this way exact guidance and synchronous driving of the side pressing blocks 16 is guaranteed, so as to prevent any relative displacement between said blocks and the material layer 7. Since the blocks circuit in a path oriented in the vertical plane, the total width of the press can be kept to a minimum.
To enable stationary electrode plates to be used for dielectrically heating the material layer 7, the press sur-face of the support elements of one press chain, in the illustrated embodiment the upper press chain 8,has the ~l~Z895 form of a plurality of metal rods 23 arranged transversely of the longitudinal direction of the press belt 1. The rods 23 are electrically insulated from one another and, in the illustrated embodiment, are held together by means of three vertically extending support plates 24 made of a suitable insulating plastics material and arranged in the longitudi-nal direction of tne press belts. The plates 24 are provided at their upper edges with a longitudinally extending metal rail 25, said rails being arranged to co-act with support rollers 26 mounted in a frame structure.
For the purpose of dielectrically heating the layer of material, the press includes at least one high-frequency ge-nerator (not shown) which is connected to two electrode plate segments 28 via electrical connecting lines 27. Each elec-trode plate is divided into two sections 28, so as to leave a space for the central sup,?ort plate 24 to pass through. If the central support plate is not required, the electrode plates may have the form of one piece structure. I~hen using a greater number of support plates 24, said plates can be further divided into smaller sections. In all events the metal rods 23, which function as small dielectric electrodes, will distribute the electrical field over the whole width of the layer of material. The lower press chain 9 is earthed and serves as the other electrode in the dielectric heating sy-stem. In the illustrated case, the side pressing blocks 16 are made of an insulating plastics material, to avoid direct sparking between the electrodes. Arranged between the rods 23 and the press belt 1 is a smoothing layer 29 of an in-sulating plastics material, which prevents the rods 23 from leaving an imprint in the pressed product. Alternatively, thc spaces between the metal rods 23 can be filled with a suitable insulating material.
As beforementioned, the use of mutually spaced and mutually insulated metal rods enables a sufficlently large voltage drop to be obtained over a relatively short length to r?ermit t~o adjacent electrode plates connected to differ-ent high frec~uency yenerators to be placed relatively close - to one another without creatin~ problems due to interference.
This enables the capacity of the press to be increased while enabling the size of said press to be decreased in comparison with a press having co-running electrode plates. In addition, the risk of certain parts of the layer 7 of material not being heated to the desired extent is eliminated.
The aforedescribed embodiment is not limitive of the invention, but can be modified within the scope of the accom-panying claims. Thus, the number and design of the electrode plates can be varied as desired and required. Further, the layer of material can be restrained laterally by other means than the illustrated side pressing blocks. The invention can also be applied with products where there is no need to re-strain the sides of the layer. As will be understood, the upper and lower press belts and the support chains may change places, such that the electrode plates are located beneath the heat-treatment zone. The upper press belt may also be omitted, provided that the space between the rods is filled with insu-lating material or that smoothing, insulated plates are arranyed on the underside of the rods in each support element.
It is also possible to omit the lower press chain and/or the lower press belt. By the term "rods" as used above and in the following claims is meant any body, irrespective of shape, which has a finite width and extends transvers~y of the press chain.

Claims (7)

What is claimed is:
1. A continuously operating heat-treatment press with dielectric heating of a continuously advanced layer of ma-terial under pressure, including for example glue-coated wood chips, said press being of the kind which includes at least one endless, continuously running press chain formed of mutualiy linked support elements, for maintaining a ver-tically acting press force on the material layer, wherein the press surface of the support elements in the press chain com-prises mutually electrically insulated metal rods extending in the transverse direction of the chain; and at least one stationary electrode plate connected to a high frequency generator is arranged adjacent said metal rods.
2. A press according to claim 1, comprising a plurality of sequentially arranged, mutually insulated electrode plates, each of which is connected to a separate high fre-quency generator.
3. A press according to claim 1, wherein the metal rods in each and every one of said support elements are held to-gether by means of at least two vertically extending support plates made of an insulating material and extending in the longitudinal direction of the press belts, said plates being arranged to transfer the press force to said metal rods.
4. A press according to claim 3, wherein when using more than two support plates, each electrode plate is divided in its longitudinal direction, to permit passage of the further support plates.
5. A press according to claim 1, wherein a continuously running press belt of insulating material is arranged between the press chain and the layer of material.
6. A press according to claim 1, wherein a smoothing layer of insulating material is arranged on the surface of the support elements facing the layer of material.
7. A press according to claim 1, wherein said press chain is arranged to press the material layer against a continuously running press belt arranged on the opposite side of the material layer, said press belt being made of steel and being earthed.
CA366,298A 1979-12-12 1980-12-08 Continuously operating press Expired CA1132895A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7910239-8 1979-12-12
SE7910239A SE419617B (en) 1979-12-12 1979-12-12 CONTINUOUS WORKING CURE PRESSURE

Publications (1)

Publication Number Publication Date
CA1132895A true CA1132895A (en) 1982-10-05

Family

ID=20339541

Family Applications (1)

Application Number Title Priority Date Filing Date
CA366,298A Expired CA1132895A (en) 1979-12-12 1980-12-08 Continuously operating press

Country Status (9)

Country Link
US (1) US4316709A (en)
BE (1) BE886596A (en)
CA (1) CA1132895A (en)
DE (1) DE3046546A1 (en)
FI (1) FI803809L (en)
FR (1) FR2471856A1 (en)
GB (1) GB2065019B (en)
IT (1) IT8068886A0 (en)
SE (1) SE419617B (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATE29641T1 (en) * 1982-01-30 1987-09-15 Sicowa Verfahrenstech DEVICE FOR HEATING A STRING OF ELECTRICALLY CONDUCTIVE MATERIAL AND USE THEREOF.
USRE33467E (en) 1985-01-30 1990-12-04 International Paper Company Induction sealing of paperboard
US4637199A (en) * 1985-01-30 1987-01-20 International Paper Company Induction sealing of paperboard
US4825625A (en) * 1986-12-17 1989-05-02 International Paper Company Sealing method and apparatus for high capacity aseptic form, fill, and seal machines
GB2255522B (en) * 1991-04-23 1994-02-16 British Aerospace Progressive curing of composite materials
DE4438729A1 (en) * 1994-10-29 1996-05-02 Siempelkamp Gmbh & Co Press for continuous mfr. of plywood or chipboard
FR2755115B1 (en) * 1996-10-29 1999-01-22 Pinette Emidecau Ind DEVICE FOR TRANSFERRING AND EXTRACTING, RELATIVE TO A WORKSTATION, A SHEET OF STICKY MATERIAL AND TRANSFORMING PRESS USING THE SAME
US6080978A (en) * 1998-09-28 2000-06-27 Heatwave Drying Systems Ltd. Dielectric drying kiln material handling system

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2433067A (en) * 1942-06-26 1947-12-23 George F Russell Method of and apparatus for highfrequency dielectric heating
DE823632C (en) * 1948-10-02 1951-12-06 Siemens Schuckertwerke A G Device for heating goods under pressure by means of an electromagnetic high-frequency capacitor field
US2697254A (en) * 1950-03-14 1954-12-21 Bruce A Gordon Dry process of manufacturing pressboard
US3096161A (en) * 1957-09-16 1963-07-02 Owens Corning Fiberglass Corp Heat setting of binder of fibrous masses
CH459036A (en) * 1967-02-09 1968-06-30 Reemtsma H F & Ph Method and device for the production of a strip-like material using a fibrous carrier substance and a dust, in particular for the production of tobacco foils
CA898902A (en) * 1969-06-30 1972-04-25 C. Clark James H.f. heating apparatus
DE2258652A1 (en) * 1972-11-30 1974-06-06 Siempelkamp Gmbh & Co Continuously heated belts for chipboard press - using induction heating of endless metal strip running between plate type endless belt and board
US4112162A (en) * 1974-03-27 1978-09-05 Svenska Utvecklingaktiebolatget Structural chipboard wood beam
DE2722348B1 (en) * 1977-05-17 1978-11-02 Baehre & Greten Method and device for heating a fleece

Also Published As

Publication number Publication date
SE7910239L (en) 1981-06-13
GB2065019B (en) 1983-04-20
SE419617B (en) 1981-08-17
DE3046546A1 (en) 1981-08-27
US4316709A (en) 1982-02-23
GB2065019A (en) 1981-06-24
FI803809L (en) 1981-06-13
BE886596A (en) 1981-06-11
IT8068886A0 (en) 1980-12-11
FR2471856A1 (en) 1981-06-26

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