A METHOD OF MANUFACTURING A COATED DOOR OR PANEL

Field of the Application

The present application relates to a panel and to a method for producing the panel having first and second opposing major surfaces, the first major surface simulating a framed-up panel of the type comprising an infill panel and a pair of spaced apart stiles joined by a pair of spaced apart rails which together extend around the infill panel. The present application also relates to techniques for the industrial production of wood- based products and more particularly to bonding pieces of wood-based products together during such processes. These may be used in the production of panels.

Background

Wood panels of the type which are referred to as framed-up panels are used

extensively, for example, as apartment doors, doors for cabinets, cupboards, panels for coffins, panelling for walls, ceilings and the like. In general, such panels comprise a frame formed by spaced apart vertical stiles joined by spaced apart horizontal rails which together surround an infill panel or a plurality of infill panels. Traditionally, the stiles, rails and infill panel would have been constructed separately from hardwood, such as for example, mahogany, oak and the like and then assembled.

An example of a traditional door construction is illustrated in figure 2, which illustrates how the infill panel 20 is held within a frame 10 formed by the stiles 12, 14 and rails 16, 18. Conventionally, the stiles and rails would have been joined by tenon joints or similar and bonded together with an appropriate adhesive. At the same time, a tongue 22 around the perimeter of the infill panel would have been seated in a co-operating groove 24. Typically, the tongue 22 and groove 24 would not have been bonded with adhesive so as to allow for the infill panel to expand and contract relative to the frame so as to reduce the risk of warping. A disadvantage of such a construction is that dirt and grime can accumulate in the dry joint formed by the tongue and groove. For decorative purposes, the infill panel may be formed with a centre section 26 which is raised relative to the tongue 22. The boundary between the centre section and tongue may be a vertical (as shown) bevelled or curved profile. Similarly, the infill panel may have decorative features, channels, grooves, or other shapes routed or otherwise formed provided on the outward facing surface.

Due to the relatively high cost of higher quality woods, panels are now commonly constructed using modern wood-based products include for example plywood, fibreboard e.g. medium density fibreboard (MDF), particle board also known as chipboard and oriented strand board. Whilst the materials employed, may be different, it is common to try to produce a panel which mimics the form of the traditional panel construction. An example of a cross section of such a panel 30 is shown in figure 3.

These approaches are based on the premise that materials such as MDF may be machined with relative ease.

The general approach is to commence the process with a single substrate of wood- based material e.g. a sheet of MDF. The front surface of the laminar piece is then machined using routing/milling machines to provide a desired surface profile for the front of the door, for example to mimic the traditional shape of a panel with rails 32,34 stiles and infill panel 36.

A veneer 38 is then provided to cover the front of the panel and sides of the panel to provide a surface finish which mimics the conventional surface finish of a traditional panel. The rear of the panel may be pre-coated with melamine 40 or another veneer.

Conventionally, the veneer 38 is a synthetic veneer applied using a membrane press.

The present application is directed at solving waste problems associated with manufacturing panels with synthetic veneers, which are typically Polyvinyl chloride (PVC) films. The advantage of synthetic veneers is that when heated they are extremely flexible which allows them to conform to the surface profile of a previously machined surface. This allows for the front and sides of the panel to be covered in the same process with a single layer of the same material.

The conventional technique for applying a synthetic (e.g. PVC) veneer is to employ a membrane press.

The process involves placing a number of previously prepared panels onto the bed of the membrane press. A layer of adhesive is applied to each of the surfaces of the panels to be coated.

A layer of PVC, typically from a roll, is then placed over the panels and clamped into place in a frame of the membrane press which forms an airtight seal with the bed of the press. A top unit is then used to cover the PVC and frame.

The top unit has one or more heaters which are employed to heat the PVC film. As the PVC is heated, it softens. A vacuum pump connected to the bottom unit causes the PVC film toward the flatbed. At the same time, the top unit is pressurized with air pressure. This combination of vacuum, pressure and heat ensures that the PVC veneer is bonded to and matches the profile of the major face and sides of the panel.

Once this process has completed, the individual panels are then separated, and excess plastic is trimmed.

To ensure a professional finish, the PVC is required to be of a suitable thickness that when softened it had the necessary ability to stretch and cover the profiles and surface depressions, and most important to retain the various design patterns on the vinyl and without significant distortion. Conventionally, this thickness has been established and required to be 0.4mm for standard product, and 0.5 mm for gloss versions, the cost of which are in general in the region of€4, for the standard material, and€5 for the gloss version per m ² .

Although different size membrane presses are available, typically, a membrane press requires a minimum of 3.85 m ² of PVC material to allow for the seal with the frame, which typically results in a usable area of approximately 2.27 m ² on the flat bed.

This area in turn is generally sufficient for six-715x495mm doors. It will be appreciated that this results in a waste factor of approximately 42%. This factor can rise significantly when smaller door sizes are pressed.

With an estimated 250,000 PVC doors produced in Ireland alone per week, this waste factor equates to approximately 3,000 metric tons of waste including the PVC material and barrier paper used to coat the bed of a glue machine to prevent adhesive sticking to the bed. It will be appreciated that when considered globally the figure is considerably higher.

The present application in a first aspect seeks to provide an improved method of manufacture which reduces the amount of waste material that results from making panels.

A second aspect, which may be used in combination with the first aspect, is directed at bonding thinner sheets together to form thicker sheets of wood-based products. Such techniques are commonly employed in furniture and joinery making, for example in making doors or frames for fitted kitchens, windows or wardrobes. The pieces employed in such manufacture are generally wood based. Such wood based products may include but are not limited to solid hard or soft woods, plywood, fibreboard e.g. medium density fibreboard (MDF), particle board also known as chipboard and oriented strand board.

For decades, the bonding of wooden strips together to create a larger panel or wood section has been carried out. The requirement to do so this is because of the limited supply of suitable wood in the market with the result that smaller size of planks or strips dominate in the market place. Accordingly, to obtain a larger size, a conventional approach is to bind smaller pieces together.

From the early days when wood strips were first bonded with animal glues, to the present day where synthetic and many other forms of glues are available, the general process remains the same.

The first step is in the process is to apply a layer of adhesive to a first piece and more particularly to the surface of the first piece to be bonded.

The surface of the first piece with the adhesive is then brought into contact with the surface of the second piece. The two pieces are then held together under pressure to allow the adhesive to cure. Traditionally and as is the process still used today, the two pieces are clamped together and left to cure overnight.

Increasingly, manual clamps are replaced by larger presses in a technique which is referred to generally as pressing.

Traditionally, this pressing process involved pressing the two pieces together in a press under pressure and leaving overnight to allow the adhesive to sufficiently cure. This technique is commonly referred to as cold pressing. Whilst several panels may be pressed at the same time, the press is required until the adhesive has cured.

Alternatively, hot pressing is a technique in which heat is applied during the pressing process.

The advantage of hot pressing is that the time required for curing is significantly reduced and in this context a figure of approximately 1.5min per 1 mm of panel thickness is exemplary of the time required, meaning that bonding two 10mm panels is achieved in a time of 15 minutes as opposed to being required to be left overnight, i.e. a period of at least 12 hours.

Regardless of the process, a period of time is required to allow the curing to occur. This time is referred to as the cure dwell time.

In the context of factory production, the cure dwell time adds significantly to the manufacturing time and occupies additional factory space to allow for the panels to be stored whilst curing.

Whilst hot pressing reduces the cure dwell time and thus improves the throughput, it has caused other problems. Such problems include that the heat from the process can give rise to panel distortion, which means that panels coming from hot presses may be required to be stacked on top of each other so as to cool and flatten out, which in turn disrupts the production process.

There are a variety of adhesives which may be employed in bonding wood together. These include animal glue, polyurethane glue, polyvinyl acetate (PVA), Urea

Formaldehyde (UF)

Animal glue, especially hide glue, was the primary adhesive of choice for woodworking, including furniture, for many centuries. It is manufactured from rendered collagen from the skins (hides) of animals. Hide glue is still used today in specialized applications, such as making musical instruments but is otherwise not employed.

Polyurethane glue (trade names include Gorilla Glue ^R ™ and Excel ^RTM ) is becoming increasingly popular for use in DIY, but is not generally employed in factory assemblies. PVA glue is an aliphatic rubbery synthetic polymer. It belongs to the polyvinyl esters family and is a type of thermoplastic.

UF glue, also known as Plastic Resin Glue, is a range of synthetic resins produced by the chemical combination of formaldehyde (a gas produced from methane) and urea (a solid crystal produced from ammonia).

Aliphatic resin emulsions, commonly referred to as "yellow glue" or "carpenter's glue", has a similar use profile and relative ultimate strength as PVA. The two glues differ in grip characteristics before initial set, with PVAs exhibiting more slip during assembly and yellow glue having more initial grip.

Cyanoacrylates are a family of strong fast-acting adhesives, commonly referred to by the brand name SUPERGLUE ^R ™. They have application in bonding small pieces together but are not employed for bonding larger pieces together since by the time the adhesive has finished been applied to one of the surfaces to be bonded, the adhesive applied first has already cured. Additionally, the cost of these adhesives is of an order of magnitude higher than that of PVA or UF adhesives.

In the context of factory assembly of panels for making furniture and similar

applications, PVA and UF are the primary adhesives employed used where large areas of panel have to be glued and are used in both hot and cold pressing. Accordingly, a second aspect of the present application aims to overcome the problems associated with the heat of hot pressing whilst seeking to reduce cure dwell times in the factory environment so as to improve line production to avoid the need for storage on the factory floor. The second approach at the same time aims to reduce the requirement for extra expensive bonding equipment.

Summary

The present application provides a method which allows for thinner synthetic films to be employed and allows for a better utilization of film area. The method also allows for the use of alternative veneers, such as wood, polypropylene or paper based veneers.

A first aspect of the application provides a method of manufacturing a panel having a first face and a second face opposite the first face, with the second face having a visual appearance of rails and stiles arranged about an infill panel. The method comprises the steps of:

a) providing a substrate, the substrate having a first surface and a second surface opposite the first surface, the first surface defining the first face of the panel, with the second surface having an infill panel region, rail receiving regions, and stile receiving regions;

and subsequent to step a) completing the following steps:

b) fixing rail pieces to the rail receiving sections to present the appearance of rails on the front face; and

c) fixing stile pieces to the stile receiving regions to present the appearance of stiles on the front face.

A veneer may be applied to the infill panel region prior to performing steps b and c.

A step feature may be formed in the substrate surrounding the infill panel region, wherein the rails and stiles are shaped to co-operatively engage with the step feature. The stile pieces and rail pieces may be assembled together as a frame before being fixed to the substrate. The individual stile pieces may be machined from a substrate to form a desired profile for the stile pieces. This may further include the step of applying a veneer to a surface of the machined substrate.

The individual rail pieces may also be machined from a substrate to form a desired profile for the rail pieces. Equally, this may further include the step of applying a veneer to a surface of the machined substrate.

In a second respect of the present application, a panel is provided having a first major face and a second major face opposite the first face. Referring to the first major face as a front face and the second major face as a rear face, the front face may have a visual appearance of rails and stiles arranged about an infill panel. The panel comprises: a substrate, the substrate having a first major surface and a second major surface opposite the first major surface, the first major surface defining the rear face of the panel, and the exposed part of the second major surface being the infill panel;

rail pieces fixed to the second major surface to present the appearance of rails on the front face; and

stile pieces fixed to the second major surface to present the appearance of stiles on the front face.

The infill panel may be covered with a first veneer. The individual stiles may be covered with a veneer which is non-contiguous with the veneer of the infill panel. Similarly, the individual rails may be covered with a veneer which in turn is non-contiguous with the veneer of either the stiles or of the infill panel.

The first veneer suitably extends from the infill panel under the edges of the rail and stile pieces. The sides of the panel extending between the front and rear faces may have an edging strip fixed thereto.

The substrate may be formed from multiple sheets of material, e.g. MDF, which are laminated together. In this respect, a second aspect of the present application provides for such a method of lamination.

More specifically, the second aspect provides an economic method of industrially bonding wood-based materials eliminating the use of heated presses and labour requirements. The method comprises the steps of applying a layer of first adhesive to a first surface of a first piece of wood-based material and applying droplets of a second adhesive to a first surface of a second piece of wood-based material. The first surface of the first piece is then pressed against the first surface of the second piece. This pressing is suitably performed in an industrial press. The first adhesive is selected to have a fast cure time relative to the cure time of the second adhesive.

In this context, a suitable choice for the first adhesive is a cyanoacrylate. A suitable choice for the second adhesive is a polyvinyl acetate. The combination of these two adhesives has been shown to be particularly effective.

The second adhesive may be heated on the first surface of the second piece prior to the step of pressing. This heating may be performed by an electric heater, for example an infra-red heater. The assembled piece of wood-based material may be removed from the press after the first adhesive has cured. After removal, the assembled piece may be stored for a period of time sufficient to allow for the second adhesive to cure.

The industrial press may be selected to be capable of applying a pressure of at least 200KN/m ² . Desirably, the pressure is applied uniformly across the area of the surfaces.

The droplets of first adhesive are generally spaced apart from one another by a distance of between 3 and 10 cm. The droplet spacing selected may depend on the rigidity of the first and second pieces and the droplet volume. The individual volume of each droplet is suitably in the range of 000023ml to 25ml.

The method is particularly suited to joining sheets of wood based material greater than 1 m x 1 m. The wood-based material of at least one of the first and second pieces may be hard wood, soft wood, plywood, fibreboard (including MDF), particle board and oriented strand board.

The application also extends to a sheet of material produced by such a method of this second aspect.

Such a sheet of material will comprise two sheets of wood based material bonded together by an adhesive layer. The adhesive layer will have areas, in which the adhesive layer comprises a mixture of a first adhesive and a second adhesive.

Separating the areas with the mixture will be areas of the adhesive layer where only a first adhesive is present.

Description Of Drawings

The application will be more clearly understood from the following description of some examples with reference to the accompanying drawings, in which:

Fig. 1 is a front view of a panel known in the art;

Fig. 2 is a cross section view of a first manner of construction along line A-A’ of Figure 1 which is known in the art;

Fig. 3 is a cross section view of a second manner of construction along line A-A’ of Figure 1 which is known in the art;

Figure 4 is a perspective view of a panel according to a first aspect of the present application;

Figure 5 is a front view of the panel of figure 4;

Figure 6 is a section view at the points indicated as B’ in figure 5;

Figure 7 illustrates an exemplary method of making the panel of figure 4;

Figure 8 illustrates the assembly of rails and stiles into a frame for use in the method of figure 7; Figure 9 illustrates the forming of an exemplary stile;

Figure 10 illustrates the steps of assembly of a thick panel from two thin panels; and Figure 1 1 is a flowchart corresponding to the steps of assembly of Figure 10.

DETAILED DESCRIPTION

In the detailed description which follows, reference will be made to an exemplary orientation of a panel for ease of explanation. This panel will be described in the context of having two major surfaces opposing one and other, namely a front and a rear surface, with side surfaces extending between them, with the panel having a top side surface, a bottom side surface, a left side surface and a right side surface. It will be appreciated that all of these are used for the assistance of the reader reviewing the description in the light of the drawings. It should be understood, that the applicant does not intend to be limited to the particular orientation which is described and shown in the drawings and that in the claims which follow, such references to a specific orientation are omitted in favour of relative terms. Equally, it will be appreciated that such relative references may be taken from the description and that the use of terms such as for example, front and rear, top and bottom, upper and lower, left and right are to be taken as being relative and not absolute. Thus, as an example reference to a front major surface and rear major surface, may be taken as being a reference to a first major surface and an opposing second major surface.

The present application provides a panel, as shown in Figure 4, which resembles a conventional panel in the art. The panel has a front (major) surface 102 that has the visual appearance of an infill panel 120 surrounded by a frame. The frame in turn has the visual appearance of being formed with a left stile 1 12, top rail 116, right stile 1 14 and bottom rail 118. The rear (major) surface 104 of the panel may be planar in nature and covered with a suitable material. The left stile is on the opposite side to the right stile and spaced apart therefrom in the middle by the infill panel, at the top by the top rail and at the bottom by the bottom rail. Similarly, the top rail is opposite the bottom rail and spaced therefrom by the infill panel. The outer edge of the left stile is defined by the left side of the panel. The inner edge of the left stile abuts the left hand side of the top rail, the left hand side of the infill panel and the left hand side of the bottom rail.

Similarly, the outer edge of the right stile is defined by the right side of the panel. The inner edge of the right stile abuts the right hand side of the top rail, the right hand side of the infill panel and the right hand side of the bottom rail. At the same time, the outer edge of the top rail partially defines the top side of the panel with the remaining part of the top side defined by the top sides of each of the left and right had stiles. The inner edge of the top rail abuts the infill panel. Similarly, the outer edge of the bottom rail partially defines the bottom side of the panel with the remaining part of the bottom side defined by the bottom sides of each of the left and right had stiles. The inner edge of the bottom rail abuts the infill panel on the opposite side of the infill panel to that of the inner edge of the top rail.

The front and rear surfaces are in a plane defined by a vertical axis and a horizontal axis. The longitudinal axis of each of the stiles are parallel with the vertical axis and the longitudinal axis of the rails are parallel with the horizontal axis.

As will be explained in greater detail below, the panel is formed separately in two sections which are then bonded together.

The first section is a substrate 122 in which the infill panel is formed. Surrounding the infill panel is a rear part 112a of a left stile 1 12, a rear part 1 16a of a top rail 1 16, a rear part 1 14a of a right stile 1 14 and the rear part 1 18a of a bottom rail 118. The rear surface of the substrate defines the rear surface of the panel. The front surface of the substrate partially defines the front surface of the finished panel. More specifically, it provides the surface of the infill panel. The second section which is fixed to the substrate is a frame which provides a front part 1 12b of the left stile 1 12, a front part 1 16b of the top rail 116, a front part 1 14b of the right stile 114 and the front part 1 18b of a bottom rail 1 18.

The panel will now be further explained with reference to an exemplary method of fabrication which will now be described.

The method will be explained in the context of forming the first section (substrate) and then affixing the second section (frame) to it. In practise, the two steps may proceed in parallel or the frame may be fabricated first.

With reference to Figure 7, the method commences with a substrate with front and rear surfaces 145, 104 corresponding to the orientation of the front and rear surfaces of the finished panel.

The substrate is suitably a wood-based material. The wood based material may be, for example, one of a high density, medium density or low density fibre board, low grade wood, reconstituted wood, chip board and oriented strand board. Although, other materials may also be employed including for example composite materials, plastics materials.

The thickness of the substrate, i.e. the distance between the rear and front surfaces, is selected to correspond to at least the thickness of the desired infill panel. The substrate may be formed from one or more sheets of thinner material so as to make up a desired thickness. A process for forming a substrate from several layers is described below with respect to figures 10 and 1 1.

The rear surface 104 of the substrate may be pre-coated with a veneer 140 prior to the subsequent steps of the process described below. Equally, the veneer may be applied as a step in the process. The veneer, for example, may be a layer of plastics material or a wood based veneer. Such a plastics material would include, for example, melamine.

The panel is placed on the bed of a CNC machine or similar machine with the rear face 140 placed down on the bed.

In a second step, the front surface 145 of the substrate is machined to form the desired shape of an infill panel.

In the exemplary arrangement shown, the infill panel is shown as a raised inset panel 120 in which the infill panel has a raised section 154 relative to a panel border section 150.

The inner edge of the panel border section defines an edge to the raised section.

The outer edge of the border section defines where the inset panel will meet the rails and stiles.

The edge 152 of the raised section may be shaped to have a concave, convex, bevelled or straight edge depending on the style desired. It will be appreciated that more complex profiles are also possible.

At the same time, the rest of the surface of the front surface of the panel is machined so as to be substantially co-planar with the border of the infill panel.

Depending on the style required, the panel may have a raised portion, be flat or be recessed. Equally, the infill panel may have recessed, or embossed shapes presented thereon, which may be obtained by programming the CNC machine appropriately.

Once machined, the substrate may be removed from the CNC machine. It will be appreciated that in contrast to the conventional machining performed when machining a panel for a membrane press assembly (per Figure 3), there is no closed shape requiring the cutting bit to be withdrawn from the workpiece. Thus when machining the infill panel in step b, the cutting bit may be run along the panel in a series of motions without having to withdraw the cutting bit. This dramatically reduces machine time.

In a fourth optional step, a layer of adhesive is applied to the front surface of the substrate and in particular to the surface of the infill portion of the substrate and extending beyond the border section.

A pre-cut section of veneer is then applied to cover the area of applied adhesive. This veneer may be any suitable veneer.

As an alternative to applying an adhesive in liquid form, a film adhesive may be used. A film adhesive may have been pre-applied using a rolling machine to the back of the veneer.

As the extent of stretching required is minimal, the veneer may be a synthetic, wood or paper based veneer.

The veneer is then pressed against the substrate, for example using a die press or vacuum press.

A membrane press may also be used. However, as the nature of the stretching is considerably less, it is not necessarily required.

Once the veneer is affixed to the substrate, the panel is machined for example by a CNC machine to remove material about a peripheral area of the front surface of the panel.

The peripheral area 156 corresponds generally to the region of the finished panel where the frame comprising the rails and stiles will be fixed. Suitably, the inner edge of the peripheral area does not extend to the border 158 but leaves an overlap region 160 where the stiles and rails will overlap the veneer of the inset panel.

The machined peripheral area defines a step 162 with the overlap region. The machining step also removes any surplus veneer outside of the step.

At this point, the substrate is ready to receive the frame which provides the front parts of the rails and stiles. The process of making the frame is described in detail below, but for the purposes of explanation here is taken as having already being formed.

Adhesive is employed to bond the frame to the substrate.

In an advantageous approach which dramatically reduces the time for handling whilst keeping costs low, is to combine the use of a fast adhesive with a slow adhesive. This technique is described in greater detail below in the context of laminating panels together.

The slow setting adhesive may be one which have a set time of at least several hours, an example of such an adhesive would be PVA. In contrast, the fast setting adhesive might have a set time measured in seconds or minutes, and may for example be a cyanoacrylate.

A layer of slow set adhesive is applied to the bottom surface of the frame 170.

At the same time, droplets of fast set adhesive are applied at spaced intervals to the peripheral area of the substrate.

The frame is then brought into contact with the substrate and the two are pressed together.

The advantage of this approach of using a slow set adhesive in combination with a fast set adhesive is that a strong bond is formed by the fast adhesive which achieves a strong bond in less than 90 seconds. The strong cured fast set adhesive then acts as a clamp which allows the panel to be handled quickly with a superior bond formed once the slow set adhesive has cured.

The frame has front surface and a rear surface. The front surface of the frame has the outline shape corresponding to the rails and stiles of a traditional door and defines an opening in the centre for abutting the infill panel.

The rear surface of the frame is shaped with a rebate along its inner edge (facing the opening) at the rear. This rebate 176 is shaped to co-operate with the shape of the step 162. To facilitate assembly the rebate may be shaped to be slightly larger than required to accommodate the edge so as to allow ease of placing the frame onto the substrate. A slow set mastic or other material may be applied as a bead prior to fixing the frame to the substrate so as to fill the gap between the rebate and step.

The front and inner edges (surrounding the infill panel) of the frame may be provided with a veneer on them. As a result, when the frame is bonded to the substrate, the front surface of the panel will have a veneer on it.

A final step in the assembly process is to provide an edging strip to each of the sides of the panel. This edging strip is suitably a veneer similar to those employed to cover the top of the frame and infill panel. An edging machine may be employed to fix the edge. Alternatively, it may be performed using a hot transfer process.

An advantage of forming the infill panel as a substrate separate from that of forming the front of the rails and stiles is that the amount of veneer required is significantly less. At the same time, the choice of veneers that may be used is increased since there is no longer a need to stretch the veneer to cover the overall shape of the infill panel, rails and stiles in a single step. Thus, it is possible to use a thinner PVC veneer than conventionally required in a membrane press process.

At the same time, the resulting panel has a front surface which resembles a traditional panel with rails, stiles and an infill panel.

It will be appreciated that as the veneer is applied to rails and stiles and the infill panel prior to the assembly of the frame and substrate, that the net result is that there are different sections of veneer rather than a single section of veneer covering the entire panel.

Thus the infill panel is coated with a first section of veneer which is separate to the sections of veneers on the rails and stiles. At the same time, the sections of veneer on the rails and stiles will be separate.

Where the veneer has a grain, the grain will be selected to run along the longitudinal axis of the stile, rail or infill panel. Thus, the grain of the infill panel and stiles may run vertically with the grain of the rails running horizontally. The manner of constructing the frame will now be described.

Although, the Frame may be constructed as a single piece by machining from a single substrate and subsequently veneering the frame as a whole, a preferred approach is to form each of the rails and stiles as parts and assemble them together as this allows for particular effects to be achieved and in particular for grain patterns to be readily presented on the stiles and rails which are orthogonal to one and other, which can mimic the grains of traditional doors, where, as mentioned above, conventionally the grain would run parallel to the longest axis of individual rails and styles. In the exemplary arrangement, the frame is made from two stile parts 112b, 1 14b and two rail parts 1 16b, 1 18b. The profiles of the stile and rail parts are selected to give a desired surface profile for the front of the panel corresponding to that of stiles and rails.

In this context, it will be appreciated that a desired profile may be provided along the outer edges of the stiles and rails. More often however, the outer edges have a straight edge.

In this context, it is more common for the inner edges to have a curved or bevelled profile for aesthetic reasons.

A rebate is formed at the inner edge of each of the rails and stiles to the rear, which is shaped to co-operate with the step defined on the substrate.

It will be appreciated that the general shape of stiles and rails is such that they facilitate producing multiple stiles or rails at the same time from a single length of material. The length of material once machined and veneered may be separated with a cutting step into individual rails and stiles as required.

Accordingly, a significant advantage of the present application is that long sections can be machined. After machining, they may be veneered. It will be appreciated that the advantage of this approach is that the veneer may be sized to correspond to the required size for the machined material and as result there is no significant waste from this veneering process.

Subsequently the length may be cut to form individual stiles and rails. This means that the overall processing time and cost is reduced significantly.

The process of forming the rail and stile parts will now be explained in the context of forming a stile. The process commences with a piece of material corresponding generally to the width and thickness of the intended stile. In the exemplary arrangement, the length of the piece of material is shown to be that of a finished stile for ease of illustration. It will however be appreciated that the steps may be applied to longer lengths of material from which individual stiles or rails may be segmented in a final step. The piece 190 may be of the same material as that of the substrate forming the infill panel.

In a subsequent step, the piece may be machined to form a desired profile 192 on the inner edge of the stile. Equally, if desired, a profile may be provided on the outer edge of the stile and the top and bottom edges. In one arrangement, the piece is moved in a linear fashion past a cutting blade which forms the desired profile.

A rebate 176 is then formed along the inner edge of the stile piece. It will be appreciated that the rebate and profile may effectively be formed in the same step by using two separate cutters positioned on a line along which the piece is moved.

A veneer may then be applied to the top surface of the part. The veneer may also extend to cover the inner edge and wraps around under the rebate.

The veneer may be applied by applying a layer of adhesive and then using a profile wrapping machine to apply the veneer. It will be appreciated that this may also be part of the in-line process forming the profiles and the rebate.

At this juncture, the process of forming a stile or rail is the same.

Indeed, as explained above, they may be made at the same time and then segmented from longer lengths of material.

In this context, the difference between a rail and stile will be that the profile formed on each end of the rail where the rail will abut a stile, is suitably shaped to have a mirror profile 198 of that of the stile to allow the two to mate together. This profile can be formed when cutting (using a profiled cutter - routing bit) as part of the segmenting of rails from a longer piece. In contrast, when segmenting stiles, conventionally, a straight cut is performed. For aesthetic reasons, the rails may be selected to slightly thinner than the stiles so as to provide a visual effect that they are clearly at different levels so that the joint is highlighted so as to differentiate that they are formed separately.

Once individual rail and stile parts have been formed, a final step is to assemble the rail and stile parts together. This may be done with any suitable method including the use of dowels, tenons or an adhesive. In the context of using an adhesive, the use of an adhesive may be as described above using a combination of a fast and slow set adhesive.

Suitably this step is performed with a jig and press as would be familiar to those in the art for frame making. The jig ensures that the pieces are aligned correctly with the press then forcing the pieces together under pressure.

This step may use the technique described above using a fast set adhesive on one surface to be joined with a slow set adhesive on the other. Such a technique is described in greater detail below in the context of laminating large panels.

The frame is then ready for assembly with the substrate as previously described.

It will be appreciated from the manner of construction that the forming of the substrate, rail parts and stile parts allow for machining in a linear fashion without requiring withdrawal of a bit from the work piece and using smaller bits as is generally the approach employed in machining closed corners. Thus, whilst the construction may appear to involve more steps than that of machining a panel from a single sheet of MDF, the overall machine time can be less with the present method.

While the panels have been described as having a front surface shaped to form a framed-up panel suitable for use as a door for a cupboard, it will be appreciated that the panel may be provided for many other purposes. It is envisaged that the rails need not extend perpendicularly to the stiles, but rather, may be at any angle or angles to the stiles.

It is also envisaged that the infill panel may be of other shape, and where the infill panel is provided with a raised surface having at least two opposite edges curved, it is envisaged that the rails or stiles adjacent the curved edges of the raised surface of the infill panel may be similarly shaped. Additionally, it is envisaged that the infill panel may be of hexagonal, octagonal or other desired shapes, and in which case, the rails extending between the stiles would be appropriately formed and located. It is also envisaged that the rail or rails adjacent the top of an infill panel may be arched or arranged to form an arch.

While in the case of the panel described the method for producing the panel has been described for producing a single panel only, it is envisaged that the method for producing the panel may be such as to enable a plurality of main substrates laminated with the main veneer sheets to be formed for a plurality of panels from one continuous sheet of substrate material. In which case, where the continuous sheet of substrate has been machined and laminated and had respective frame members affixed, the sheet could then be cut to form respective panels.

It is envisaged that the veneers employed may be of a plastics material, foils, or the like which may or may not simulate a wood finish, and may or may not be provided with a grain. Needless to say, a veneer sheet of any other suitable or desired material may be used. It is also envisaged that edging strips of material other than foil may be used, and indeed, in certain cases, it is envisaged that the edging strip may be a wood veneer, or indeed, may be a strip of wood, or plastics material, or any other suitable material.

While a rough outline of the infill panel has been described as being formed in the main substrate by machining using a routing tool, outline of the infill panel may be formed in the main substrate using any other suitable machining, or any other forming or shaping means, for example, moulding, extrusion, or the like. It is also envisaged that in many cases it may not be necessary to form or machine a rough outline of the stiles and infill panel on the main substrate, in which case, the stiles and infill panel would be formed in the front surface of the main panel member by compression moulding during lamination of the main veneer sheet to the main substrate. This would be possible in cases where the main substrate is provided by a sheet of material of relatively low density, such as, for example, low density chipboard, fibreboard and the like.

Additionally, whilst the door described above has been described in the context of having a single infill panel, it will be appreciated that a door may be formed with any number of infill panels and in such cases, it is envisaged that one or more parallel intermediate stiles may be provided intermediate the stiles, and it is also envisaged that a number of intermediate rails may be provided intermediate the rails.

It will be appreciated that the present application provides a method which reduces the amount of PVC material required for a panel.

The improvement is achieved by making the door as a substrate and a frame. As a result, those parts of the finished panel which represent individual rails or stiles are formed as front and rear parts.

A rear part of each rail and stile is formed as part of the panel substrate.

A front part of each rail and stile which may be formed as a skeleton unit of a frame is then fixed onto the corresponding substrate and the resulting shape forms the panel.

The advantage of this approach is that surface coatings may be applied separately to the substrate unit and the frame reducing the amount of veneer material required compared to when the front and sides of the door are covered at the same time in a membrane press frame.

Also as the need for stretching in the PVC veneer is significantly eliminated, a thinner PVC veneer may be employed further reducing cost and waste. At the same time, by incorporating the infill panel as part of the overall substrate for the rails and stiles, it eliminates the presence of unhygienic dry grooves. At the same time, the use of a single substrate to form the rear of the panel gives stability to the panel. It also allows the panel to be produced with a flat hygienic rear surface which in use is positioned nearest the cabinet interior. This is in contrast to the traditional door construction where the infill panels floats within the dry groove formed in the rails and stiles and where it is prone to ingress of dirt and grime. Making the door in two parts facilitates the use of a slender dimensioned and

competitive door units which also reduce transport costs further reducing the

environmental cost.

At the same time, making the door in two parts allows a saving in machining time and motive power as there is no closed corners to slow down for.

Equally, when made in two parts, the door when assembled eliminates any possibility of delaminating, or warping. There are further advantages. For example, the conventional approach dictates that the infill panel, rails and stiles are covered with the same PVC material dictating that the infill panel, rails and stiles are generally the same colour and that the grain follows the same direction throughout. The advantage of the present method manufacture is that different colours or effects may be provided. Thus a door may be formed with a dark oak infill panel and light oak stiles and rails. Similarly, an infill panel may be selected to have a high gloss finish with the stiles and rails having a contrasting matt finish. Although, the associated process of manufacture appears to be more complex than the conventional approach of machining from a single sheet of MDF and using a membrane press, there are a significant number of advantages.

Firstly, as the veneers employed are not required to stretch, a thinner and less expensive PVC membrane may be employed. It is also possible to use alternative veneers including wood, polypropylene and paper based veneers.

Additionally, when making the panel in two parts it is possible to reduce the wastage from that of a membrane press as the areas to be covered may be done so selectively rather than requiring an area to cover the entire frame of a membrane press.

Although, the panel described above has been explained in the context of applying a veneer, it will be appreciated that the veneer may be replaced by any other surface coatings. Thus, for example, the veneers may be omitted and instead the finished panel may be painted. The described method still has advantage as the overall machine time may be significantly less as the need for machining closed corners is eliminated.

The second aspect of the present application is directed at assembling wood-based sheet materials and in particular for making a thicker sheet from two or more thinner sheets in a factory for furniture and joinery fabrication. In particular, the application is directed at assembling wood-based sheets using two or more thinner sheets which are laminated together with an adhesive under pressure in a press. These sheets may be employed for making door substrate panels and the like.

The present application overcomes the problem of cold pressing, i.e. the need to leave the panels in a press for an extended duration of time, typically more than 8 hours, commonly overnight.

The process of assembly 220 will now be described with reference to figures 10 and 1 1. The process commences with a first step 222 (STEP A) of selecting of two sheets 202, 204 of wood-based product, i.e. two wood-based sheets. The sheets will be of the order of several mm thick. Accordingly, individual sheets may have a thickness in the range of 4mm to 20mm. Where the method is employed to bond a smaller piece onto the surface of a larger piece, the thickness may be less, for example in the range of 1-5mm, suitably for example 3mm. This for example could be the situation described above where top part of rails and stiles are bonded to the substrate. Although where such a thin piece is used it will be appreciated that other modifications may have to be made including not using a lip around the infill panel as a rebate would difficult with a thin rail/stile piece and so there would not be a drop-down section.

More typically, the individual sheets would have a thickness in the range of 6mm to 16mm. However, it will be appreciated that the overall thickness of the materials to be bonded will generally only be limited by the height of the press opening.

The sheets are suitably sized to fit into the press used in a subsequent step in the process. Accordingly, the sheets may be of a standard size for wood-based products, and thus may be greater than 1 m x 2m in surface size. Conventional sizes would include 1220 x 2440 mm, 1250 x 2500 mm, 1500 x 2500, 1500 x 3000 mm, 1525 x 3050 mm and 1525 x 3660 mm.

At the same time, it will be appreciated that door panels and the like practically tend to have a minimum size and so if an individual door, for example, for the front of a kitchen drawer was being produced from two sheets bonded together, then the surface area being bonded would correspond to the dimensions of the drawer panel. In this context, it is likely that for sheet materials, the sheets will have a minimum dimension along one axis of 10cm and along another of 30cm corresponding to the likely practical smallest panel size, although as explained above the technique may be employed with smaller pieces. More practically, the dimensions of the first surface area are likely to be greater than 1 m x 1 m, as significant advantages arise at such dimensions where it would be entirely impractical for cost or manufacturing reasons to employ fast set adhesives for such large areas.

Equally, it will be appreciated that the process may be employed for joining non-sheet like materials, e.g. for forming an adhesive joint between two pieces, such as for example to join rails and stiles in a panel or to join wood sections so as form a desired wood profile with a minimum of machine time and waste.

The sheets may be cleaned or otherwise prepared to remove any dust or similar material which may interfere with a proper bond. In a second step 224 (STEP B), a fast set adhesive, suitably a cyanoacrylate adhesive is selectively applied to a first sheet 202. In particular, droplets 206 of adhesive are applied at intervals onto a first surface of the first sheet using a suitable dispensing system 208.

Various types of dispensing systems are known for dispensing cyanoacrylate adhesive in manufacturing applications, including pinch tubes, diaphragm valves and pneumatic- actuated syringe dispensers and air-free syringe dispensers.

In the case of the latter, the syringe and piston are made of polypropylene and polyethylene respectively, which minimizes air and moisture infiltration. The piston and tip cap are coated with a noncontaminating release agent to inhibit bonding between the adhesive and the plastic surfaces. The piston is advanced in the syringe by a linear actuator driven by a stepper motor. The linear actuator ensures that a specific volume of adhesive material is displaced during each dispensing cycle. Such linear actuators allow for a droplet size as small as 0.00023 ml. At the same time, an end-of-cycle“draw-back” prevents dripping of the adhesive. An X-Y positioning system may be used in

combination with the dispensing system to ensure that the droplets of adhesive are applied at regular intervals across the sheet. Suitably, the droplets are less than 25ml in volume.

Alternatively, a series of dispensers could be arranged at intervals in a line, with the length of the line corresponding to the width of a sheet, with the sheet being placed on a conveyor which transports the sheet in a direction transverse to the line allowing for droplets to be deposited at regularly spaced intervals across the width and length of the sheet.

A third step 226 (STEP C), applies a layer 210 of slow set adhesive to the second sheet 204. The slow set adhesive may for example be a PVA type adhesive or similar.

With reference to the terms cure or set, which are used herein interchangeably, fast and slow are relative with respect to one and other. A fast set may be taken to indicate a cure time which is of the order of seconds or minutes, for example less than six minutes, and a slow set time may be taken to indicate a cure time that is of the order of hours, for example at least one hour. Generally, it may be taken that a slow set has a cure time at least ten times that of fast set. More typically, this ratio will be greater than fifty.

The third step may use a roller applicator 212 to apply the slow set adhesive to the second sheet. More particularly, the second sheet may be transported along a conveyor passing over the roller applicator 212. Other techniques that could be employed to dispense the slow set adhesive may include spraying. Similarly, one or more dispensers may be employed to dispense the slow set adhesive with a squeegee or similar tool employed to spread the slow set adhesive evenly on the second surface.

In an optional step, the surface of the second sheet may be heated. This heating may be achieved by passing over a heater such as an infrared heater so as to partially dry the slow set adhesive. This partial drying can reduce the overall cure time for the slow set adhesive.

It will be appreciated that the second and third steps may be performed simultaneously, or the third step may be performed in advance of the second step.

A fourth step 228 (STEP D) in the process brings the sheets together. This step aligns the sheets and then brings them together.

In a fifth step (STEP E), the two sheets are pressed between the plates 216 and 218 of a press, suitably a cold press. The pressure applied by the cold press, which is suitably at least 20psi (138kPa), causes the individual droplets of fast set adhesive to spread out by a factor of ten to twenty times in surface area. A more general pressure range for a press to obtain reliable results is between 65psi (448kPa) and 150psi (1003kPa).

At the same time, the pressure causes the slow set adhesive to mix with fast set adhesive. This starts a chain reaction polymerizing the fast setting adhesive and which then achieves solid state and relative speaking an almost instant cure (measured in seconds). The moisture present in the slow set adhesive increases the bond speed of the fast set adhesive. At the same time, the presence of the slow set adhesive appears to improve the bond strength of the fast set adhesive.

The two sheets are left under pressure in the cold press for a period of time sufficient to allow the fast set adhesive to cure. This time will be reasonably short in the range of 30 to 90 seconds. It will be appreciated that the sheets may be left in the press longer and so this time represents a minimum time rather than a maximum time. The precise time required will depend on a number of factors including the spacing of the dots of fast adhesive, the thickness of the sheets being bonded and the pressure of the press, but will be generally less than 90 seconds.

Once the fast set adhesive has cured, the sheets may be removed from the press and placed in a suitable storage area to allow a period of time for the slow set adhesive to cure. This for example may be overnight. The bonding achieved by the fast set adhesive effectively acts like a clamp keeping the two sheets tight together allowing for them to be handled. At the same time, the pseudo clamping performed by the cured fast set adhesive allows for the slow set adhesive to cure and form a strong bond over the entire panel.

Equally, it will be appreciated that the bonded sheets may be processed further in advance of the slow set adhesive curing, provided the process does not introduce excessive force. Thus as an example, the surfaces may be machined in a CNC or milling machine, sanded or coated with a surface finish (e.g. paint or varnish).

Thus the previous interruption to the production flow necessitated by the slow cure time of the adhesive may be substantially eliminated.

It will be appreciated that once the sheets have been removed, the press may then be re-used for subsequent sheets. The effect of this is that the cycle time for a (cold) press is reduced from the conventional time frame of hours (overnight) to minutes.

An advantage of the present approach is that as only a relatively small amount of fast set adhesive is used, it may readily be applied to a sheet in the time available before the adhesive cures. In contrast, were fast set adhesive to be applied to cover the entire surface of a sheet, the adhesive might already have cured by the time the entire sheet is covered. Equally, an advantage of the present approach is that the cost of the fast set adhesive is relatively small since a reasonably small amount is employed.

The spacing and size of the droplets of fast adhesive will be dependent on a variety of factors, including the nature of the fast adhesive, the materials being joined and the thickness of the sheets.

Generally speaking, the size and spacing of the droplets will be selected to result in a bond which is able to withstand handling of the sheets when removing them from the press. In this context, it will be appreciated that such a determination can be readily be made by experimentation. It has however been determined that typically the required inter droplet spacing may be between 3 and 10 cm. A consequence of the inter drop spacing and size of the droplets is that when the droplets are spread out under pressure, the result will be that there will be areas between the two sheets where there is a mix of the slow and fast set adhesives (i.e. centred on where the droplets are placed) and areas where there is only slow set adhesive present.

A further advantage of the described method is that heating requirements for areas in which materials are stored may be reduced as the need for keeping moisture content low is not as important.

Thicker sheets will typically require larger droplets spaced at greater intervals with thinner sheets requiring smaller droplets at closer intervals. This is because thinner sheets are more flexible necessitating the distance between points of bonding to be closer. It is for this reason, that a lower limit of 4mm was selected for the thickness of the sheets. However, it is the combined thickness that is important and so a thinner sheet, e.g. less than 4mm for example 2 or 3mm, may be bonded to a thicker sheet, e.g. greater than 8 mm.

An observed advantage of the process is that a sheet produced by the present process appears to be stiffer than a sheet produced using a slowing set adhesive.

The present technique is intended for industrial manufacture where the press used would be an industrial press and where the forces would be applied by relatively large plates, of at least 1 m ² in cross sectional area. In such industrial presses, the pressure is applied by an actuator rather than manually. Typically, the actuator is a pneumatic, hydraulic or electric actuator.

In this context, an advantage of the present approach is that a cold press may be used in place of a hot press since once adequate pressure is applied, a sufficient bond will be created by the fast set adhesive which will allow handling of the sheets.

Another approach which may be employed with the method of fast bonding is to produce a“shaker style” panel which comprises a recessed area surrounded by rails and stiles. This approach does not necessarily result in a saving of plastic but does reduce wood waste and machining time. The approach comprises starting with a planar substrate of wood based material. This material which may be made up of more than one sheet laminated together, for example, using the method described above for joining thinner panels. The area of the substrate is at least that of the finished panel but may be formed as part of a larger piece. Thus, the dimensions of a major surface of the substrate may be greater than 30cm by 30cm. The thickness of the substrate is suitably the thickness of the finished panel in the region of the recessed area of the panel. This thickness may be in the range 8mm to 20mm and more likely in the region of 10mm to 18mm. In a second step, a frame is prepared comprising rails and stiles elements. These elements form the front visible aspects of the rails and stiles of a finished panel. The rear of the panel is suitably planar with no distinction between centre panel, stiles and rails. The frame may be provided as a single piece or as individual pieces. The frame (either as a whole or as pieces) is then adhered to the substrate using the adhesion technique above with fast and slow set adhesives. In this case, the thickness of the frame pieces may be relatively low, e.g. between 2 and 6mm as the substrate acts as a support. With lower thickness for the rail and stile pieces, the step of forming a rebate to abut with a step formed on the infill panel may be impractical and thus may be omitted.

Once assembled, the panel may be coated with a surface finish, e.g. by painting.

Similarly, a veneer may be applied for example in a membrane press. The rear face of the panel may be pre-coated with a plastic such as for example melamine or other surface veneer.

The advantage of this approach is that it is no longer necessary to machine a recessed panel from a substrate of MDF or other wood based material.

In this context, it will be appreciated that the approach may also be used to provide an infill panel front surface (not necessarily the planar form of a shaker style). Thus a raised panel portion might be affixed separately to the underlying substrate using the fast bonding process. As such an infill could be formed continuously by machining, there would be a saving in machine time, in contrast machining an infill panel at the same time as rails and stiles requires using different machine bits close to where a corner is formed.