TECHNICAL FIELD

The present invention relates to layer formation.

In particular, but not necessarily exclusively, the present invention relates to the production of a product having multiple layers that are structural in nature.

BACKGROUND ART

In preferred embodiments, the present invention has special application to producing layered products from partially rigid layers such as single face corrugated paperboard. However, this should not be seen as limiting because the present invention can be applied to the formation of layers from other materials.

Single face corrugated paperboard is well known as it is used extensively in industry, especially in packaging where it is used as protective padding for wrapping objects.

Single face and double face corrugated paperboard is also used as a basic component in the production of many structural objects such as boxes, panels and paper pallets to name a few.

Sheets of single face corrugated paperboard can be bonded together (laminated) to form multi-layer corrugated paperboard of various thicknesses and strengths. One reason for the wide use of such corrugated paperboard is its relatively light weight, rigidity and strength.

Single face corrugated paperboard is made by bonding a fluted sheet, typically of corrugated medium (generally recycled paper) onto a liner sheet. The liner sheet is typically Kraft paper although other materials may be used.

Conventional methods for laminating sheet materials typically involve a number of reels of the material to be laminated which are aligned above and/or behind each other. Each layer is drawn out from a reel (usually in a horizontal plane) and fed through machinery, in such a way, that the layers are laid on top of each other. The adjacent layers are then bonded to each other, for instance, by application of adhesive, and typically, pressure and/or heat.

While this process can work well, it is not suitable for all circumstances. For example, the process only works when there is preformed material already on the reels.

For example, this process is not suitable if it is desired to laminate material immediately after production of the individual layers, that is, before the layers have been stored on a reel.

It would therefore be desirable to have a laminate formed from layers of material cut from a single wide layer that has only just been manufactured or is on a single large reel.

Another problem with this method is that considerable space is usually required to hold the multiple reels of layers in alignment with one another so that layers are overlaid as they are drawn off their respective reels prior to the formation of the multi-layered product. This is because the reels are typically stacked above one another. Alternatively the reels have to be aligned along a central common draw axis which extends longitudinally along the centre of the layers as they are drawn off their respective reels. This requirement that there be a common longitudinal axis for the sheet material coming off the reels is necessitated by the fact that cardboard is substantially inflexible about a lateral axis. This is problematic as discussed above in relation to the continuous in-line production of layers cut from a single sheet of cardboard substantially immediately after the single face paperboard has been produced.

Providing a storage area for the pre-formed reels of the sheet material (strips) whilst they await lamination, in addition to the consequent transportation and handling of the reels, is also labour intensive and expensive.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION

As used herein the term 'strip of material', or grammatical variants thereof, refers to a long or substantially continuous narrow length of material.

According to a further aspect of the present invention there is provided a method of aligning laterally disposed strips of material existing in a common plane for the purpose of laminating said strips characterised by the step of tilting at least one strip of material so as to be angled with respect to the common plane to enable redirection of said angled strip(s) to align with and become longitudinally overlaid with at least one strip which remains in the common plane.

According to one aspect of the present invention there is provided a method of creating a multi-layered product from multiple strips which are laterally disposed with respect to one another and which are substantially positioned in a common plane, the method including:

a) feeding the laterally disposed strips to a first set of individual support guides wherein at least one support guide is angled with respect to said plane, and then

b) feeding the strips to a second set of downstream support guides aligned along a common longitudinal draw axis with respect to the strips, such that the strips coming off the second set of support guides are substantially aligned on top of one another prior to being combined together to form a multi-layered product. The term 'common plane' as used herein refers to a plane (real or imaginary) which is created if one extends a common lateral axis of the strips in the direction in which the strips are to be laminated. In general the common plane may be substantially horizontal.

According to another aspect of the present invention, there is provided a multi- layered product produced by the aforementioned process.

According to another aspect of the present invention there is provided a machine configured to be operated in accordance with the aforementioned method.

In one embodiment the machine may utilise preformed reels of strip material wherein the machine is arranged so that the reels rotate about an angled rotational axis with respect to a common plane. It will be appreciated that such an embodiment represents a retro-fit option to existing machines which have reels stacked above one another.

In some embodiments the rotational axis of the reels may be angled with respect to the vertical.

In one preferred embodiment the machine may include support guides capable of receiving strips of material, wherein the strips are initially located in a common plane and wherein a number of the support guides are angled with respect to said common plane.

Preferably the angle of the support guides may be adjustable to take into account variations in the torsional stress of the strips which may be imparted from the manufacture process and which may vary dependent on a variety of factors as will be appreciated by a person skilled in the art.

It is envisaged that the present invention will have particular application to the manufacture of multi-layer corrugated paperboard. Therefore, in preferred embodiments of the present invention, the strips are lengths of single face corrugated paperboard. It should be appreciated however that the present invention can be applied to other materials, particularly those not having an ability to flex in a lateral direction- such as cardboard for example.

Having regard to the foregoing, it is envisaged that the present invention will most likely be applied to making a multi-layered corrugated board from strips cut from a single sheet of material.

For example, the present invention will have particular use in the manufacture of product from single face corrugated paperboard directly after it has been manufactured as a continuous web of single face corrugated paperboard. It should be appreciated that the aim of the present invention is to take a number of strips which are in a common plane and then layer them on top of each other to form a multi-layered board.

As a consequence of the relative lateral stiffness of the strip material, the strips which are side by side cannot be immediately conveyed to that part of the plant where the layers can be placed directly on top of each other. This is because to meet together at a central aligned axis, the strips created from the outer edges of the original sheet need to angle more to a central axis than those strips near the middle of the sheet. Given the degree of lateral inflexibility of the strips, this cannot be achieved within a short distance, unless some other mechanism has been provided. It is to address this particular problem that the inventor has designed support guides which can support the strips of material, while angling them with respect to the original plane from which the strips were created.

The support guide has a rod that can support a strip or strips of material during the formation of the multi-layered product.

Preferably, the support guide includes a rod with stops positioned at either end thereof. The rod supports the strips of material and the stops act to prevent the strips of material from sliding off the rod. In a preferred embodiment, the support guide has a shape similar to that of a weightlifter's dumbbell. In some further preferred embodiments the support guide may include a guide bar to further help retain the strip on the rod.

In some embodiments of the present invention, the support guide stops are movable so as to accommodate strips of different widths.

In preferred embodiments, the rod of the support guide is positioned so a vertical plane running through the longitudinal axis of the rod is substantially perpendicular to the leading edge of the sheet of material from which the strips are formed.

A support guide which includes a rod with stops positioned at either end thereof wherein said support guide is adapted to be angled with respect to a common plane in which strips to be laminated initially exist. Most preferably the support guide may be adapted so the angle is adjustable.

It is envisaged there may be a number of different ways the support guide can be adapted so as to be angled. In preferred embodiments the support guide may include one support member which depends down from the rod. In some embodiments the support member may be simply welded to a frame. Preferably, the support member includes an aperture for connection to a frame which provides adjustability of the angle.

In some other embodiments, the support guide may include two support members which support the rod so that it can rotate. Preferably, the support members each include a slot through which a bolt or other fastener can pass to connect to a frame which provides for adjustability of the angle.

Preferably, there is provided multiple support guides positioned in line with each other.

The support guides may be supported by a number of means, but in preferred embodiments this is envisaged to be a frame having multiple rungs which are supported by legs above the ground.

It is envisaged that if the sheet of material is originally presented in the horizontal plane, then the angling of the support guides would be within the vertical plane. For example, the support guides may be tilted sideways within their vertical plane. This tilt may be achieved by a variety of means. For example, a plate may be attached to the support guide rod and pivotally connected to a rung via a nut and bolt.

In operation, a first strip of material is placed onto a support guide which has been tilted to accommodate the angle that the strip has to take from the sheet to the support guide. For example, if the support guides are mounted substantially central with respect to the sheet of material, centre strips from the sheet will require only minimal tilting of the support guide. Outer strips however will require a significant tilt.

It should be appreciated that the present invention can be used with strips of any number, from two upwards.

Once each of the strips has been accommodated on support guides and thereby assisted through the angling of same, they are then fed to non-angled support guides such that all of the strips are now aligned on top of each other in readiness for formation into a multi-layered product.

In one embodiment the strips are pulled continuously forward by a laminating conveyor that also pulls the strips individually over a glue roller. The glue roller applies discrete droplets of adhesive to the flute tips prior to entering the laminating conveyor that holds the webs together for bonding.

It should be appreciated that the actual formation of the multi-layered product may be by a variety of means and is not thought to be part of the present invention. This can be however through the application of glue and pressure and/or heat.

The present invention has a number of advantages over the prior art.

The present invention provides a means by which a structural multi-layered product can be readily formed in a single run, as part of a continuous in line process, involving taking two or more strips of material that have been cut from a single sheet as it is manufactured. This process obviates the need to first place the strips onto reels or other storage devices prior to manufacture of the laminated product.

By obviating the need for reels, certain preferred embodiments of the present invention can provide machinery that does not need significant headspace or additional room to accommodate the reels.

The process is continuous in its operation of making multi layered stacked corrugated board from a single width single face web. Therefore the present process does not need multiple corrugators or intermittent operation as occurs when multiple single face reels are first manufactured and then joined afterwards. In contrast to the present invention, the previous process utilizes extremely large reels of single face material with a fixed reel length. As a consequence such reels need many replacements which resulting in many stoppages and poor quality due to the creation of many taped joins.

BRIEF DESCRIPTION OF DRAWINGS

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:

Figure 1 a perspective view of the machine in accordance with one embodiment of the present invention;

Figure 2 illustrates a side view the machine in figure 1 having strips of material placed thereon;

Figure 3 a close up view of a support guide in accordance with one aspect of the present invention;

Figure 4 shows a perspective view of the machine in accordance with a further preferred embodiment of the present invention;

Figure 5 shows a side view of the machine in Figure 4; and Figure 6 shows an end view of the machine shown in Figures 4 and 5.

BEST MODES FOR CARRYING OUT THE INVENTION

Figures 1 and 2 illustrate a machine now termed a layer combiner generally indicated by arrow (1) in accordance with one aspect of the present invention.

The layer combiner (1 ) has a number of rungs (2) supported by an outer frame (3) in substantially a horizontal plane.

The frame (3) is likewise supported by legs (4) so that the rungs (2) are held above the ground.

Each rung (2) has a support guide (5) attached thereto. The support guides (5) are aligned substantially with the rungs (2). Each support guide (5) is also aligned substantially with each other along the central axis of the frame (3).

A support guide (5) is shown in greater detail in Figure 3.

The support guide (5) includes a central rod (6) near the distal ends of which are stops (7). The stops (7) can have their position altered on the rod (6) so as to accommodate strips of material (see Figure 2) of varying widths. Optionally the support guide (5) has a guide bar (500) which creates with rod (6) an enclosed path (501) through which the strip of material passes which further helps retain the strip of material on the support guide (5).

The rod (6) is also connected to a plate (7) which is joined by a bolt (not clearly shown) which passes through an aperture (9) to connect the support guide (5) to a rung (2). Preferably the fit of the pivot (in this case nut and bolt) with respect to an aperture (not shown) in the rung (2), is such that the support guide (5) can have its angle adjusted in the vertical plane and held there until moved with some force.

The machine illustrated in Figures 1 and 2 has been set up to accommodate the manufacture of a board from four strips of material. It should be appreciated however that the present invention can be used to manufacture multi-layered boards made up of two or more strips (or layers).

In operation, continuous single face corrugated paperboard is cut into four strips (1Oa-IOd) which are aligned in substantially the same common plane to each other as the paperboard comes off a corrugator (not shown). The strips while they are in this common plane with respect to one another are shown by arrow (10) as they are deposited onto an intermittent conveyor which moves slowly every 5 seconds in direction Y to move the strips (10) away from the corrugator to prevent piling up of the strips. It is to be noted that the common plane in the embodiment depicted in the figures is horizontal.

Each of the four strips (10) is fed to a separate support guide (5). A first edge strip (10a) is fed to a support guide (5a) such that strip (10a) is supported by the central axis of the support guide (5a) and between the stops thereon. The support guide (5a) has been angled to accommodate the angle that the strip (10a) has to adopt to travel from the outer edge of the board to the support guide (5a).

The strip (10a) passes not only over the top of the support guide (5a), but also over the top of support guides (5e) and (5T). It should be noted that at this stage of the process, the support guides (5e) and (5f) are positioned approximately in the horizontal plane.

Likewise, another edge strip (10b) passes over support guide (5b). Centre strips (10c) and (1Od) likewise pass over support guides (5c) and (5d). All of the support guides (5) have been angled to accommodate the respective orientations of the strips (10).

Once the strips reach the support guide (5e) they are stacked on top of each other and are substantially aligned enabling the formation of a multi-layered board through whatever means.

The layering of the strips is shown in exaggerated form coming off the support guide (5f) to illustrate the layering effect.

With respect to Figures 4 - 6 like reference numerals have been used to refer to like elements to those shown in Figures 1 and 2. The key difference this embodiment has over that shown in Figures 1 and 2 is the inclusion of uprights (200) which connect the support guides (5) to the rungs (2). The uprights (200) have differing heights which helps facilitate alignment of the strips to cover one another as they reach support guide (5e).

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 the appended claims.