WO2017118614A1 - Method of producing a core material for a laminated board, and laminated board comprising such core - Google Patents

Method of producing a core material for a laminated board, and laminated board comprising such core Download PDF

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Publication number
WO2017118614A1
WO2017118614A1 PCT/EP2017/050004 EP2017050004W WO2017118614A1 WO 2017118614 A1 WO2017118614 A1 WO 2017118614A1 EP 2017050004 W EP2017050004 W EP 2017050004W WO 2017118614 A1 WO2017118614 A1 WO 2017118614A1
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WO
WIPO (PCT)
Prior art keywords
core
strips
sheet
bundle
main plane
Prior art date
Application number
PCT/EP2017/050004
Other languages
French (fr)
Inventor
Kurt Aldén
Original Assignee
Green Lite 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 Green Lite Ab filed Critical Green Lite Ab
Priority to SE1850945A priority Critical patent/SE542861C2/en
Publication of WO2017118614A1 publication Critical patent/WO2017118614A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/146—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers whereby one or more of the layers is a honeycomb structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31D—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER, NOT PROVIDED FOR IN SUBCLASSES B31B OR B31C
    • B31D3/00—Making articles of cellular structure, e.g. insulating board
    • B31D3/005—Making cellular structures from corrugated webs or sheets
    • B31D3/007—Making cellular structures from corrugated webs or sheets by cutting corrugated webs longitudinally into strips, piling these strips and uniting them
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D99/00—Subject matter not provided for in other groups of this subclass
    • B29D99/0089—Producing honeycomb structures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/28—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer comprising a deformed thin sheet, i.e. the layer having its entire thickness deformed out of the plane, e.g. corrugated, crumpled
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/18—Handling of layers or the laminate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B29/00—Layered products comprising a layer of paper or cardboard
    • B32B29/08—Corrugated paper or cardboard

Definitions

  • the present disclosure relates to a method for producing a core for laminated board materials.
  • board materials find applications in fields such as furniture, display/advertising panels and in general construction.
  • the disclosure also relates to a laminated board material which can be produced according to the method.
  • Laminated board materials having a core based on corrugated paper sheets are well known.
  • corrugated paper sheets comprise a planar sheet and a fluted sheet, which are laminated together.
  • Corrugated paper core based board materials are conventionally produced by stacking and laminating together a large number of corrugated paper sheets, turning the thus formed block about 90 degrees and sawing the block into a number of cores having a desired thickness, and laminating the thus formed cores with facing sheets.
  • US3912573 discloses a method of producing a core material for a honeycomb panel.
  • a general object is thus to provide an improved method of producing a core for a sandwich panel.
  • Specific objects include increasing production speed and flexibility.
  • a method of producing a core material for a laminated board comprises providing a sheet of material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, whereby the sheet defines first and second opposite faces, parallel with a sheet main plane, orienting the sheet such that corrugations extend substantially perpendicular to a feed direction, slitting the sheet along the feed direction, such that a plurality of elongate strips are provided, turning the strips 90 ° about their longitudinal directions, merging the strips first face to second face to form a strip bundle, whereby a bundle main plane is defined, which is substantially perpendicular to the sheet main plane of the individual strips, arranging the strip bundle to form the core to a predetermined width, and laminating at least one facing sheet to the core.
  • the strips are movable relative to each other until the facing sheet has been bonded to the core.
  • the sheet may be a so-called corrugated paper or cardboard sheet.
  • the corrugated paper sheet comprises one corrugated sheet and one planar sheet, which are laminated together.
  • the corrugations of the sheet form elongate flutes, which extend along the corrugations.
  • the plurality of strips may be anything from three strips and upward.
  • the width of the strips will be governed by the desired thickness of the core and thus the number of strips will be determined by the core thickness and the corrugated sheet width.
  • the number N of strips may be on the order of W/Tc, where W is the width of the sheet material and Tc is the thickness of the core.
  • W is the width of the sheet material
  • Tc is the thickness of the core.
  • the strips are movable relative one another such that they may shift relative to each other when the bundle is bent in the bundle main plane.
  • the strips are not glued or otherwise adhered to each other before they have been arranged to form the core.
  • the strips may be maintained continuous and transversely uncut at least through the arranging step and preferably through the laminating step.
  • the strip bundle may present a width that is smaller than the predetermined width of the core, and wherein arranging the strip bundle comprises arranging it partially across a length direction of the core and in the core main plane.
  • the bundle may be arranged in a substantially crenellated pattern in the core main plane.
  • the method may further comprise compressing the core in a direction parallel with the length direction.
  • the method may further comprise providing at least one guide member, which is moveable at least across the length direction of the core.
  • the guide member may be movable along the length direction of the core and/or perpendicular to the bundle main plane.
  • At least two or three guide members may be provided.
  • the strip bundle may present a width that is approximately the same as the predetermined width of the core and wherein arranging the strip bundle comprises arranging it such that the strips extend substantially parallel with a length direction of the core.
  • the method may further comprise pressing the core in a direction perpendicular to a length direction of the core.
  • a laminated board material comprising a core formed from strips of a sheet material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, wherein flutes formed by the corrugated layer extend in a direction substantially perpendicular to a board main plane; and a pair of facing sheets sandwiching the core.
  • a contact surface between adjacent strips is
  • the adhesive material may be e.g. a polymer resin (e.g. hot melt adhesive, a setting resin), water glass or glue.
  • the contact surface may be free from adhesive material in a zone that extends over at least 70 % of a thickness of the core, preferably over at least 80 %, at least 90 %, at least 95 % or at least 99%.
  • the only adhesive material present between a pair of adjacent strips is that which has penetrated in connection with the application of the facing sheets.
  • the core may present strips which are bent through at least 90 ° , preferably at least 135 ° or about 180 ° , as seen in the board main plane.
  • adjacent strips may present the same bend angle but different bending radii.
  • the core may be formed of a bundle of strips having equal width, said bundle being bent back and forth in the board main plane.
  • the new method provides a number of advantages, including increased flexibility in laminated sheet format: basically any width can be produced in a fully automated production line.
  • Fig. 1 schematically illustrates a process of producing a laminated board material.
  • Fig. 2 schematically illustrates the production process in more detail.
  • Fig. 3 schematically illustrates a laminated board material which can be produced according to the present disclosure.
  • corrugated sheet 20 as a starting material.
  • Such corrugated sheet may be supplied in bulk form, e.g. on a reel, or directly from a machine for its production.
  • the corrugated sheet may be made from a wood fiber based material, such as paper.
  • the corrugated sheet may optionally be impregnated and/or coated in order to reduce its ability to absorb moisture.
  • the corrugated sheet 20 presents corrugations which provide flutes.
  • the corrugated sheet comprises one corrugated sheet and one planar sheet, which is bonded to the corrugated sheet.
  • the corrugated sheet is fed in a feed direction Df from the supply to a longitudinal cutting device 21 .
  • the feed direction Df may be substantially perpendicular to the longitudinal direction of the corrugations or flutes.
  • the feed direction is perpendicular to the direction of the corrugations, but it is conceivable to feed slightly obliquely or to use a sheet in which the corrugations do not extend perpendicular to the longitudinal direction of the sheet.
  • Cutting devices 21 are known from e.g. US3912573, which was referred to above, and may include knives, saws, rotary cutters, laser, water jet or other types of cutting techniques.
  • the number of cutters 21 is selected with regard to thickness of the core that is to be provided, and thus with regard to the number of strips to be provided and the width of the sheet.
  • the cutting device 21 cuts through the sheet, thus dividing it along the feed direction Df into a plurality of strips 22. However, the strips remain connected to the supply. That is, there is no cutting in the direction across the feed direction Df.
  • Each strip 10a, 10b is then, at 22, turned approximately 90 ° about its length direction, i.e. a direction parallel with the feed direction. Preferably, all strips are turned towards the same direction.
  • the turning 22 may occur over a certain length in the feed direction Df. This length may be dependent on the width of the strips, and on the flexibility and strength of the material: a wider strip may require a longer length, as may a more brittle or weaker material.
  • the strips After the strips have been turned, they are merged 23 top surface to bottom surface to form a bundle of strips 24.
  • the bundle 24 will present principal surfaces Bp1 , Bp2 which are formed by side surfaces of the strips 10a, 10b, and which will be parallel with the principal surfaces of the core 1 that is to be produced.
  • the strips 10a, 10b forming the bundle 24 will not be held together by any adhesive, and thus the strips can move freely relative each other along their length directions.
  • the bundle 24 of strips may be arranged with its principal surfaces Bp1 , Bp2 horizontally oriented.
  • the bundle 24 of strips may be guided by one or more guide members G1 a, G1 b, G2, G2a, G2b, G3, G4, which may protrude upwardly through a support (not shown) on which the bundle 24 is transported, or which may be brought into contact with the bundle 24 from above.
  • the guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may provide multiple functions: they may collect (G1 a, G1 b) and maintain the strips in a held together bundle; they may push the bundle sideways (G2, G2a, G2b, G3, G4) i.e. in the direction transversely of the feed direction Df and they may push or hold the bundle towards the downstream direction (G2, G2a, G2b, G3, G4), as seen in the feed direction Df.
  • the guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may be used to control the layup of the bundle 24 to form the core 1 .
  • the laterally outer shape of the core 1 may be defined by rim members R1 , R2, which may run along the feed direction Df. Such rim members may thus define a core width.
  • the rim members R1 , R2 may present a portion of tapering width, whereby the core 1 which has been laid up by the guide members (G1 a, G1 b, G2, G2a, G2b, G3, G4) is compressed in a direction transversely of the feed direction Df.
  • the core may be provided with facing sheets 1 1 a, 1 1 b to form the laminated board material.
  • the facing sheets may be attached to the core by any conventional type of adhesive or glue.
  • Examples include hot-melt adhesive and setting polymer resins.
  • such glue or other adhesive is applied to the core, e.g. by means of a pair of glue rollers 25a, 25b; one 25a applying glue to the upper side of the core and the other 25b applying glue to the lower side of the core.
  • the facing sheets 1 1 a, 1 1 b may be applied continuously, from respective reels, or sheet-wise.
  • the guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may be used to lay up the bundle of strips in any desired pattern for forming the core.
  • the bundle of strips in a substantially crenellated pattern. That is, the bundle of strips will extend across the feed direction Df, from one side edge of the core, across the entire width of the core, to the other side edge of the core, bend 180 ° and then extend all the way back to the first side edge of the core, bend 180 ° , and so on.
  • a first pair of guide members G1 a, G1 b, or a guide member and a rim may be used to collect the strips to and merge them into a bundle 24 of strips having the desired width, as described above.
  • a second guide member G2, G2a, G2b may engage the bundle of strips downstream of the first guide member G1 a, G1 b and push the bundle 24 of strips towards one of the side rims R1 , R2, such that the bundle is held between the guide member G2, G2a, G2b and the side rim R1 , R2.
  • the bundle is allowed to shift over, and thus be fed past, the second guide member, at least when it moves in the direction transversely of the feed direction Df.
  • This second guide G2, G2a, G2b member may then follow in the feed direction, such as to provide some pressure towards the downstream core 1 which has already been laid up.
  • a third guide member G3 may then engage the bundle of strips from the side opposite to which it was engaged by the second guide member G2, G2a, G2b. This third guide member may push the bundle of strips towards the opposite side rim, while allowing the bundle to shift over, and thus be fed past, the third guide member. This third guide member may then follow in the feed direction, such as to provide some pressure towards the downstream core which has already been laid up.
  • a fourth guide member G4 may be provided, may perform the same action as the third guide member G3, but in the opposite sideways direction.
  • the second guide member may be disengaged and return to repeat its function.
  • the third guide member will likewise be disengaged and repeat its cycle.
  • the bundle of strips may merely be provided along the feed direction. This will limit the width of the board material thus produced to that of the bundle 24.
  • a single pair of stationary guide members G2a, G2b may be used, just a pair of rims R1 , R2 or a rim and a guide member.
  • the finished board material may 2 be characterized as follows.
  • each strip 10a, 10b will present a zone, extending in the thickness direction Y of the board material 2, in which the front and back faces of the strip is free from adhesive material.
  • the exact width of this zone is determined by how far the adhesive provided when laminating the facing sheets to the core has penetrated into the core. It is estimated that the adhesive free zone may extend over at least 70 % of the core thickness, preferably over at least 80 %, at least 90 % or at least 95 %.
  • the adhesive free zone will extend substantially continuously along the respective strip. It is noted that random and/or unintentional occurrence to an extent that is insufficient to impede the relative movement between the strips may occur.
  • the board material 2 will exhibit portions where a bundle of strips is bent in a plane parallel with the board main plane XZ. Such bends may be about 90 ° or about 180 ° . Adjacent strips of a bundle 24 will thus present the same bending angle, but different bending radii: strips closer to a centre of the bend will have smaller bending radius and strips further away will have greater bending radius.
  • strips which are at the part furthest away from the centre will be substantially parallel with the longitudinal edge of the board, as seen in the feed direction Df.
  • the board material will also present strips 10a, 10b, which are non-parallel with each other.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)

Abstract

The present disclosure provides a method of producing a core material (1) for a laminated board (2). The method comprises providing a sheet (20) of material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, whereby the sheet defines first and second opposite faces, parallel with a sheet main plane (Sp), orienting the sheet such that corrugations extend substantially perpendicular to a feed direction (Df), slitting (21) the sheet along the feed direction, such that a plurality of elongate strips (10a, 10b) are provided, turning (22) the strips 90û about their longitudinal directions, merging (23) the strips first face to second face to form a strip bundle (24), whereby a bundle main plane (Bp1, Bp2) is defined, which is substantially perpendicular to the sheet main plane (Sp) of the individual strips (10a, 10b), arranging the strip bundle (24) to form the core (1) to a predetermined width (Y), and laminating at least one facing sheet (11a, 11b) to the core (1). The strips (10a, 10b) are movable relative to each other until the facing sheet (11a, 11b) has been bonded to the core (1).

Description

METHOD OF PRODUCING A CORE MATERIAL FOR A LAMINATED BOARD, AND LAMINATED BOARD COMPRISING SUCH CORE
Technical Field
The present disclosure relates to a method for producing a core for laminated board materials. Such board materials find applications in fields such as furniture, display/advertising panels and in general construction.
The disclosure also relates to a laminated board material which can be produced according to the method.
Background
Laminated board materials having a core based on corrugated paper sheets are well known. In most cases corrugated paper sheets comprise a planar sheet and a fluted sheet, which are laminated together.
Corrugated paper core based board materials are conventionally produced by stacking and laminating together a large number of corrugated paper sheets, turning the thus formed block about 90 degrees and sawing the block into a number of cores having a desired thickness, and laminating the thus formed cores with facing sheets.
However, such production of the core is associated with some disadvantages, which reduce speed of production and limit production capacity, which in turn lead to a higher cost of the board material.
US3912573 discloses a method of producing a core material for a honeycomb panel.
However, the method disclosed in US3912573 has a disadvantage in that the width of the core that can be produced continuously is limited. For greater width panels, it is necessary to cut the core into pieces and arrange them next to each other prior to lamination, which would substantially reduce production speed.
Hence, there is a need for an improved method of producing the core, such that the production cost can be reduced. Summary
A general object is thus to provide an improved method of producing a core for a sandwich panel. Specific objects include increasing production speed and flexibility.
The invention is defined by the appended independent claims, with embodiments being set forth in the appended dependent claims, in the following description and in the drawings.
According to a first aspect, there is provided a method of producing a core material for a laminated board. The method comprises providing a sheet of material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, whereby the sheet defines first and second opposite faces, parallel with a sheet main plane, orienting the sheet such that corrugations extend substantially perpendicular to a feed direction, slitting the sheet along the feed direction, such that a plurality of elongate strips are provided, turning the strips 90° about their longitudinal directions, merging the strips first face to second face to form a strip bundle, whereby a bundle main plane is defined, which is substantially perpendicular to the sheet main plane of the individual strips, arranging the strip bundle to form the core to a predetermined width, and laminating at least one facing sheet to the core. The strips are movable relative to each other until the facing sheet has been bonded to the core.
The sheet may be a so-called corrugated paper or cardboard sheet. Preferably, the corrugated paper sheet comprises one corrugated sheet and one planar sheet, which are laminated together.
The corrugations of the sheet form elongate flutes, which extend along the corrugations.
The plurality of strips may be anything from three strips and upward. The width of the strips will be governed by the desired thickness of the core and thus the number of strips will be determined by the core thickness and the corrugated sheet width. Ideally, the number N of strips may be on the order of W/Tc, where W is the width of the sheet material and Tc is the thickness of the core. However, depending on sheet quality, it may be necessary to provide for some excess or scrap along the long side edges of the sheet material.
In particular, the strips are movable relative one another such that they may shift relative to each other when the bundle is bent in the bundle main plane. Hence, the strips are not glued or otherwise adhered to each other before they have been arranged to form the core.
Through this method, it is possible to continuously produce a core having arbitrary width.
The strips may be maintained continuous and transversely uncut at least through the arranging step and preferably through the laminating step.
The strip bundle may present a width that is smaller than the predetermined width of the core, and wherein arranging the strip bundle comprises arranging it partially across a length direction of the core and in the core main plane.
The bundle may be arranged in a substantially crenellated pattern in the core main plane.
The method may further comprise compressing the core in a direction parallel with the length direction.
The method may further comprise providing at least one guide member, which is moveable at least across the length direction of the core.
The guide member may be movable along the length direction of the core and/or perpendicular to the bundle main plane.
At least two or three guide members may be provided.
The strip bundle may present a width that is approximately the same as the predetermined width of the core and wherein arranging the strip bundle comprises arranging it such that the strips extend substantially parallel with a length direction of the core.
The method may further comprise pressing the core in a direction perpendicular to a length direction of the core.
According to a second aspect, there is provided a laminated board material, comprising a core formed from strips of a sheet material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, wherein flutes formed by the corrugated layer extend in a direction substantially perpendicular to a board main plane; and a pair of facing sheets sandwiching the core. A contact surface between adjacent strips is
substantially free from adhesive material.
The adhesive material may be e.g. a polymer resin (e.g. hot melt adhesive, a setting resin), water glass or glue.
The contact surface may be free from adhesive material in a zone that extends over at least 70 % of a thickness of the core, preferably over at least 80 %, at least 90 %, at least 95 % or at least 99%.
Hence, effectively, the only adhesive material present between a pair of adjacent strips is that which has penetrated in connection with the application of the facing sheets.
The core may present strips which are bent through at least 90°, preferably at least 135° or about 180°, as seen in the board main plane.
For example, adjacent strips, or even all strips forming a strip bundle, may present the same bend angle but different bending radii.
The core may be formed of a bundle of strips having equal width, said bundle being bent back and forth in the board main plane.
The new method provides a number of advantages, including increased flexibility in laminated sheet format: basically any width can be produced in a fully automated production line.
Moreover, by eliminating the sawing referred to by way of introduction, enhanced tolerances can be achieved, as sawing-related defects are eliminated. Brief Description of the Drawings
Fig. 1 schematically illustrates a process of producing a laminated board material.
Fig. 2 schematically illustrates the production process in more detail. Fig. 3 schematically illustrates a laminated board material which can be produced according to the present disclosure. Detailed Description
The methods disclosed herein make use of a corrugated sheet 20 as a starting material. Such corrugated sheet may be supplied in bulk form, e.g. on a reel, or directly from a machine for its production.
Typically, the corrugated sheet may be made from a wood fiber based material, such as paper. The corrugated sheet may optionally be impregnated and/or coated in order to reduce its ability to absorb moisture.
The corrugated sheet 20 presents corrugations which provide flutes. Optionally, the corrugated sheet comprises one corrugated sheet and one planar sheet, which is bonded to the corrugated sheet.
The corrugated sheet is fed in a feed direction Df from the supply to a longitudinal cutting device 21 . The feed direction Df may be substantially perpendicular to the longitudinal direction of the corrugations or flutes.
Preferably, the feed direction is perpendicular to the direction of the corrugations, but it is conceivable to feed slightly obliquely or to use a sheet in which the corrugations do not extend perpendicular to the longitudinal direction of the sheet.
Cutting devices 21 are known from e.g. US3912573, which was referred to above, and may include knives, saws, rotary cutters, laser, water jet or other types of cutting techniques.
The number of cutters 21 is selected with regard to thickness of the core that is to be provided, and thus with regard to the number of strips to be provided and the width of the sheet.
The cutting device 21 cuts through the sheet, thus dividing it along the feed direction Df into a plurality of strips 22. However, the strips remain connected to the supply. That is, there is no cutting in the direction across the feed direction Df.
Each strip 10a, 10b is then, at 22, turned approximately 90° about its length direction, i.e. a direction parallel with the feed direction. Preferably, all strips are turned towards the same direction.
The turning 22 may occur over a certain length in the feed direction Df. This length may be dependent on the width of the strips, and on the flexibility and strength of the material: a wider strip may require a longer length, as may a more brittle or weaker material.
After the strips have been turned, they are merged 23 top surface to bottom surface to form a bundle of strips 24. The bundle 24 will present principal surfaces Bp1 , Bp2 which are formed by side surfaces of the strips 10a, 10b, and which will be parallel with the principal surfaces of the core 1 that is to be produced.
The strips 10a, 10b forming the bundle 24 will not be held together by any adhesive, and thus the strips can move freely relative each other along their length directions.
In one embodiment, where the sheet is supplied in a substantially horizontal orientation, the bundle 24 of strips may be arranged with its principal surfaces Bp1 , Bp2 horizontally oriented.
The bundle 24 of strips may be guided by one or more guide members G1 a, G1 b, G2, G2a, G2b, G3, G4, which may protrude upwardly through a support (not shown) on which the bundle 24 is transported, or which may be brought into contact with the bundle 24 from above.
The guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may provide multiple functions: they may collect (G1 a, G1 b) and maintain the strips in a held together bundle; they may push the bundle sideways (G2, G2a, G2b, G3, G4) i.e. in the direction transversely of the feed direction Df and they may push or hold the bundle towards the downstream direction (G2, G2a, G2b, G3, G4), as seen in the feed direction Df.
Hence, the guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may be used to control the layup of the bundle 24 to form the core 1 .
The laterally outer shape of the core 1 may be defined by rim members R1 , R2, which may run along the feed direction Df. Such rim members may thus define a core width. The rim members R1 , R2 may present a portion of tapering width, whereby the core 1 which has been laid up by the guide members (G1 a, G1 b, G2, G2a, G2b, G3, G4) is compressed in a direction transversely of the feed direction Df.
Once given its intended shape, the core may be provided with facing sheets 1 1 a, 1 1 b to form the laminated board material. The facing sheets may be attached to the core by any conventional type of adhesive or glue.
Examples include hot-melt adhesive and setting polymer resins.
Preferably, such glue or other adhesive is applied to the core, e.g. by means of a pair of glue rollers 25a, 25b; one 25a applying glue to the upper side of the core and the other 25b applying glue to the lower side of the core.
It is possible to apply glue or other adhesive only to the core, only to the facing sheets, or to apply glue both to the facing sheets and to the core.
The facing sheets 1 1 a, 1 1 b may be applied continuously, from respective reels, or sheet-wise.
It is possible to apply facing sheets only from above or only from below, and to then turn the half finished board for application of the next, opposing facing sheet.
It is also possible to apply both facing sheets simultaneously or with a slight offset in the feed direction Df.
The guide members G1 a, G1 b, G2, G2a, G2b, G3, G4 may be used to lay up the bundle of strips in any desired pattern for forming the core.
Specifically, it is contemplated to provide the bundle of strips in a substantially crenellated pattern. That is, the bundle of strips will extend across the feed direction Df, from one side edge of the core, across the entire width of the core, to the other side edge of the core, bend 180° and then extend all the way back to the first side edge of the core, bend 180°, and so on.
In order to provide such a pattern a first pair of guide members G1 a, G1 b, or a guide member and a rim, may be used to collect the strips to and merge them into a bundle 24 of strips having the desired width, as described above.
A second guide member G2, G2a, G2b may engage the bundle of strips downstream of the first guide member G1 a, G1 b and push the bundle 24 of strips towards one of the side rims R1 , R2, such that the bundle is held between the guide member G2, G2a, G2b and the side rim R1 , R2. The bundle is allowed to shift over, and thus be fed past, the second guide member, at least when it moves in the direction transversely of the feed direction Df. This second guide G2, G2a, G2b member may then follow in the feed direction, such as to provide some pressure towards the downstream core 1 which has already been laid up.
A third guide member G3 may then engage the bundle of strips from the side opposite to which it was engaged by the second guide member G2, G2a, G2b. This third guide member may push the bundle of strips towards the opposite side rim, while allowing the bundle to shift over, and thus be fed past, the third guide member. This third guide member may then follow in the feed direction, such as to provide some pressure towards the downstream core which has already been laid up.
Optionally, a fourth guide member G4 may be provided, may perform the same action as the third guide member G3, but in the opposite sideways direction.
Once the fourth guide member G4 has started to apply pressure in the feed direction, the second guide member may be disengaged and return to repeat its function.
Then after the second guide member has applied pressure during its second cycle, the third guide member will likewise be disengaged and repeat its cycle.
Hence, at any given time, there will be two guide members applying pressure in the downstream direction (and thus moving together with the laid up core), while a third guide member is in motion.
As another option, the bundle of strips may merely be provided along the feed direction. This will limit the width of the board material thus produced to that of the bundle 24. To this end, a single pair of stationary guide members G2a, G2b may be used, just a pair of rims R1 , R2 or a rim and a guide member.
The finished board material may 2 be characterized as follows.
As there is no adhesion provided between the strips 10a, 10b forming the bundle of strips 24, each strip 10a, 10b will present a zone, extending in the thickness direction Y of the board material 2, in which the front and back faces of the strip is free from adhesive material.
The exact width of this zone is determined by how far the adhesive provided when laminating the facing sheets to the core has penetrated into the core. It is estimated that the adhesive free zone may extend over at least 70 % of the core thickness, preferably over at least 80 %, at least 90 % or at least 95 %.
Where the same type of lamination system has been used for both facing sheets 1 1 a, 1 1 b, it is expected that penetration will be very similar on the two faces of the core 1 . Hence, the adhesive free zone will be centered about the middle of the core 1 , as seen in the thickness direction.
The adhesive free zone will extend substantially continuously along the respective strip. It is noted that random and/or unintentional occurrence to an extent that is insufficient to impede the relative movement between the strips may occur.
Moreover, in boards 2 produced according to the method where the bundles are laid up across the feed direction Df, the board material 2 will exhibit portions where a bundle of strips is bent in a plane parallel with the board main plane XZ. Such bends may be about 90° or about 180°. Adjacent strips of a bundle 24 will thus present the same bending angle, but different bending radii: strips closer to a centre of the bend will have smaller bending radius and strips further away will have greater bending radius.
Due to the compression in the feed direction Df, strips which are at the part furthest away from the centre will be substantially parallel with the longitudinal edge of the board, as seen in the feed direction Df. Hence, the board material will also present strips 10a, 10b, which are non-parallel with each other.

Claims

1 . A method of producing a core material (1 ) for a laminated board (2), comprising:
providing a sheet (20) of material comprising a corrugated layer and preferably also a planar layer bonded to the corrugated layer, whereby the sheet defines first and second opposite faces, parallel with a sheet main plane (Sp),
orienting the sheet such that corrugations extend substantially perpendicular to a feed direction (Df),
slitting (21 ) the sheet along the feed direction, such that a plurality of elongate strips (10a, 10b) are provided,
turning (22) the strips 90° about their longitudinal directions, merging (23) the strips first face to second face to form a strip bundle (24), whereby a bundle main plane (Bp1 , Bp2) is defined, which is
substantially perpendicular to the sheet main plane (Sp) of the individual strips (10a, 10b),
arranging the strip bundle (24) to form the core (1 ) to a predetermined width (Y), and
laminating at least one facing sheet (1 1 a, 1 1 b) to the core (1 ), wherein the strips (10a, 10b) are movable relative to each other until the facing sheet (1 1 a, 1 1 b) has been bonded to the core (1 ).
2. The method as claimed in claim 1 , wherein the strips (10a, 10b) are maintained continuous and transversely uncut at least through the arranging step and preferably through the laminating step.
3. The method as claimed in claim 1 or 2, wherein the strip bundle presents a width that is smaller than the predetermined width of the core, and wherein arranging the strip bundle comprises arranging it partially across a length direction (Df, X) of the core and in the core main plane (Bp1 , Bp2).
4. The method as claimed in claim 3, wherein the bundle is arranged in a substantially crenellated pattern in the core main plane (Bp1 , Bp2).
5. The method as claimed in claim 3 or 4, further comprising
compressing the core in a direction parallel with the length direction (Df, X).
6. The method as claimed in any one of claims 3-5, further comprising providing at least one guide member (G1 a, G1 b, G2, G2a, G2b, G3, G4), which is moveable at least across (Y) the length direction (Df, X) of the core.
7. The method as claimed in claim 6, wherein the guide member (G1 a, G1 b, G2, G2a, G2b, G3, G4) is movable along the length direction (Df, X) of the core and/or perpendicular (Z) to the bundle main plane (Bp1 , Bp2).
8. The method as claimed in claim 6 or 7, wherein at least two or three guide members (G1 a, G1 b, G2, G2a, G2b, G3, G4) are provided.
9. The method as claimed in claim 1 or 2, wherein the strip bundle (24) presents a width that is approximately the same as the predetermined width of the core and wherein arranging the strip bundle comprises arranging it such that the strips extend substantially parallel with a length direction (Df, X) of the core.
10. The method as claimed in any one of claims 2-9, further comprising pressing the core (1 ) in a direction (Y) perpendicular to a length direction (Df, X) of the core.
1 1 . A laminated board material, comprising:
a core (1 ) formed from strips (10a, 10b) of a sheet material comprising a corrugated layer (101 ) and preferably also a planar layer (102) bonded to the corrugated layer (101 ),
wherein flutes formed by the corrugated layer extend in a direction substantially perpendicular to a board main plane (Bp1 , Bp2, XZ); and a pair of facing sheets (1 1 a, 1 1 b) sandwiching the core (1 );
wherein a contact surface between adjacent strips is substantially free from adhesive material.
12. The laminated board material as claimed in claim 1 1 , wherein the contact surface is free from adhesive material in a zone that extends over at least 70 % of a thickness of the core, preferably over at least 80 %, at least 90 %, at least 95 % or at least 99%.
13. The laminated board material as claimed in claim 1 1 or 12, wherein the core presents strips (10a, 10b) which are bent through at least 90°, preferably at least 135° or about 180°, as seen in the board main plane (Bp1 , Bp2, XZ).
14. The laminated board material as claimed in any one of the preceding claims, wherein the core (1 ) is formed of a bundle (24) of strips having equal width, said bundle being bent back and forth in the board main plane (Bp1 , Bp2, XZ).
PCT/EP2017/050004 2016-01-04 2017-01-02 Method of producing a core material for a laminated board, and laminated board comprising such core WO2017118614A1 (en)

Priority Applications (1)

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SE1650005-0 2016-01-04
SE1650005 2016-01-04

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3192099A (en) * 1963-01-03 1965-06-29 Miller Herman Inc Furniture panel
US3912573A (en) 1971-07-28 1975-10-14 Bernard P Kunz Apparatus for producing core material for honeycomb panels
US4585381A (en) * 1983-10-06 1986-04-29 Down River International, Inc. Void filler
DE102010004865A1 (en) * 2010-01-18 2011-07-21 Daimler AG, 70327 System for continuously producing sandwich composite structure, has honeycomb core that is arranged between two cover layers, where cover layers formed by extruded fiber-reinforced plastic components

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3192099A (en) * 1963-01-03 1965-06-29 Miller Herman Inc Furniture panel
US3912573A (en) 1971-07-28 1975-10-14 Bernard P Kunz Apparatus for producing core material for honeycomb panels
US4585381A (en) * 1983-10-06 1986-04-29 Down River International, Inc. Void filler
DE102010004865A1 (en) * 2010-01-18 2011-07-21 Daimler AG, 70327 System for continuously producing sandwich composite structure, has honeycomb core that is arranged between two cover layers, where cover layers formed by extruded fiber-reinforced plastic components

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SE542861C2 (en) 2020-07-21

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