Method of forming single face corrugated board

Abstract

A method of bonding a substantially planar sheet material to a corrugated sheet material using an automated process the method characterized by the steps of a) applying adhesive in discrete amounts to the contact points of the corrugated sheet material, and b) holding the sheet materials together until a bond is formed between them.

Claims

1. A machine for making single face corrugated board without the use of steam by bonding a corrugated sheet material having one or more crests onto a substantially planar sheet, the machine comprising: a glue applicator roller having a contoured outer surface in the form of corrugations comprising a series of adjacent grooves completely encircling the surface of the roller which are spaced substantially 1 mm apart from each other and are 0.5 mm deep into which adhesive is deposited, the roller being configured to apply 0.5 mm.sup.3 of adhesive in discrete, spaced apart, pear or round shaped droplets, to the crest of the corrugated sheet material, the pear or round shaped droplets being formed as droplets, as a consequence of the adhesive being drawn out of the grooves, and wherein the roller is configured to place the droplets so they are spaced apart by a gap, such that when the droplets become spread and meet one another, the adhesive on the crests reaches a predetermined thickness; and a pressing mechanism configured to hold the planar sheet against the crest until a bond is formed between them; wherein the machine is not configured to use steam and does not comprise a boiler, pipe work or a housing to ensure containment of steam.

2. A machine as claimed in claim 1 wherein the crests of the corrugations on the roller form a spiral.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

(2) FIG. 1 shows a schematic side elevation of part of a single facer machine according to one embodiment of the present invention; and

(3) FIG. 1A shows a close up of the applicator portion of the machine in FIG. 1 according to one embodiment of the present invention.

(4) FIG. 2 shows a schematic view of an edge portion of an applicator according to one embodiment of the present invention.

(5) FIG. 3A shows a schematic side elevation of a fluted sheet with droplets of adhesive applied to the crests;

(6) FIG. 3B shows a schematic perspective view of a fluted sheet with a line of spaced apart droplets of adhesive along two of the crests; and

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) A portion of a machine for forming single faced corrugated board is generally shown by arrow (1) in the schematic side elevation shown in FIG. 1.

(8) A first corrugating roller (2) has teeth (2) arranged around the periphery of the first corrugating roller (2), the teeth (2) extending laterally across the width of the first corrugating roller (2).

(9) A second corrugating roller (3) has teeth (3) around its periphery. The diameter of the second corrugating roller (3) is substantially larger than the diameter of the first corrugating roller (2).

(10) The corrugating rollers (2 and 3) are arranged such that teeth (2) of the first corrugating roller (2) intermesh with the teeth (3) of the second corrugating roller (3) in the region indicated by number (16).

(11) The first corrugating roller (2) is powered to rotate in a clockwise direction and the second corrugating roller (3) is powered to rotate in an anticlockwise direction, as indicated by the respective dashed arrows.

(12) A planar sheet material, in the form of a sheet of Kraft paper (7), is fed around the first corrugating roller (2) and between the intermeshed teeth in the region of arrow (16). The action of the teeth as they intermesh folds the Kraft paper into a series of crests to form a fluted sheet (8).

(13) The Kraft paper may be recycled or virgin paper and ideally in the order of 90 to 150 gsm.

(14) The second corrugating roller (3) includes open passageways (not shown) so that a partial vacuum can be created inside the corrugating roller (3) by connecting a vacuum pump (not shown) to one end of the corrugating roller (3). This partial vacuum inside the second corrugating roller (3) is used to hold the fluted sheet (8) in place against the teeth (3) of the second corrugating roller (3).

(15) An applicator in the form of a glue roller (4) has an outer surface configured as a series of crests and troughs which extend around the circumference of the roller. The crests are formed by a spiral V shaped cut extending around and across the surface of the glue roller (4).

(16) Adjacent V shaped troughs (21, 22) meet at a line to form the crests (20) of the roller (4). Each crest (20) has a sharp edge as shown in FIG. 2, such that the series of crests form a zigzag pattern in cross section.

(17) The glue roller (4) is rotatably mounted alongside the second corrugating roller (3), the axis of rotation of the glue roller (4) being substantially parallel to the axis of rotation of the corrugating roller (3). The axis of the glue roller (4) is displaced from the axis of the second corrugating roller (3) by a distance such that the crests (20) of the glue roller (4) hold against the crests of the fluted sheet (8) held in the teeth of the second corrugating roller (3).

(18) A pick-up roller (5) is rotatably mounted on an axis substantially parallel to the axis of the glue roller (4), and is arranged such that the surface of the pick-up roller (5) makes firm contact with each crest of the glue roller (4).

(19) A bath (6) contains adhesive in the form of Adhesin Z9129W. The bath (6) is arranged such that the outer surface of the pick-up roller (5) is coated with Adhesin Z9129W as the pick-up roller (5) rotates.

(20) The first corrugating rollers (2), second corrugating roller (3), the glue roller (4) and pick-up roller (5) all have a width comparable to the width of the fluted sheet (8).

(21) Adhesive is transferred from the surface of the pick-up roller (5) into the troughs (21, 22) of the glue roller (4). The adhesive is carried by the glue roller (4) as it rotates at a peripheral speed corresponding to the corrugating roller when the glue roller contacts a crest of the fluted paper (8) along the contact line (9), at which point the adhesive is transferred from the troughs (21, 22) onto the crest (18) in the form of droplets.

(22) A schematic side elevation of a sheet of fluted paper, in which droplets (19) have been deposited onto the crests (18), is generally indicated by arrow 17 in FIG. 3A.

(23) FIG. 3B shows a schematic perspective view of a plurality of discrete droplets (19) deposited along a crest (18) of a sheet of fluted paper.

(24) Referring back to FIG. 1, a second planar sheet of Kraft paper, in the form of a liner (10) is pressed against the fluted sheet (8) by a tensioned belt assembly generally indicated by arrow (17).

(25) The endless belt (13) is held in place against the periphery of the second corrugating roller (3) by the action of the first guide end roller (11), second guide end roller (12), two guide rollers (14) and a tensioning roller (23) as known in the prior art.

(26) The separation of the first guide end roller (11) from the second guide end roller (12) determines the length over which the endless belt (13) applies pressure to the liner (10). This separation corresponds approximately to three quarters of the periphery of the second corrugating roller (3), this being approximately the maximum length available (so as to leave room for the first corrugating roller (2) and the glue roller (4).

(27) Tension is applied to the endless belt (13) by adjusting radially (with respect to the axis of the second corrugating roller (3)) the position of the tensioning roller (23).

(28) In practice tension in the belt (13) is adjusted to the point where damage, typically in the form of creasing or tearing of the liner and/or fluted paper, occurs. The tension, is then reduced by backing off the tensioning roller (23) to the lowest tension below this threshold where damage does not occur. The amount of tension applied to belt (13) to achieve the correct pressure of the belt (13) against the roller (3) depends on many factors including the nature of the sheet materials used for the liner and fluted sheets. The joining of the liner (10) to fluted paper (8) forms corrugated board (15).

(29) A pick (24) is located in the vicinity immediately after the guide end roller (12). The pick (24) is used to help release the bonded single face corrugated board (15) from being held by the vacuum inside the second corrugating roller (3).

(30) The rate of production of single face corrugated board (15) in this arrangement is determined by the diameter and rotation speed of the second corrugating roller (3). With the endless belt (13) extending around approximately three quarters of the periphery of the second corrugating roller (3), this fixes the rotation time at around 20 revolutions per minute, independent of the diameter of the roller (3). However, the amount produced is dependent on the diameter, D (measured in meters), of the roller (3) and is given (for the configuration described above) by 20 D meters per minute, ie., around 63 times the diameter of roller (3) (measured in meters) meters per minute.

(31) For example, a second corrugating roller (3) having a diameter of 1.6 m may produce around 100 m/min of singled face paper board.

(32) FIG. 1A is a close-up of the machine shown in FIG. 1 and shows more clearly the corrugations on the glue roller 4A.

(33) Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.