WO2013084021A1

WO2013084021A1 - Wallboard manufacturing process and apparatus therefor

Info

Publication number: WO2013084021A1
Application number: PCT/IB2011/055442
Authority: WO
Inventors: Alexander Stewart Vaughan
Original assignee: Winstone Wallboards Limited
Priority date: 2011-12-05
Filing date: 2011-12-05
Publication date: 2013-06-13

Abstract

The present invention provides a flattening apparatus and method therefor, which is used to flatten a continuous board feed against a conveyor belt to reduce surface irregularities of the wallboard feed on the side of the conveyor belt. The flattening apparatus does this by applying a uniformly distributed load over compression zone, and by reducing frictional forces on the upper surface of the continuous board feed. The flattening apparatus can comprises a set of rollers that push downwardly on the continuous board feed, the set of rollers having a spongy lining to distribute the force exerted over a compression zone, and a set of bearings to reduce the friction of the rollers on the continuous board feed. Alternately, the flattening apparatus comprises a compression arrangement for creating a layer of pressurised air between the flattening apparatus and a weight, to reduce friction and distribute the load evenly.

Description

WALLBOARD MANUFACTURING PROCESS AND APPARATUS

THEREFOR

TECHNICAL FIELD

The present invention relates to a wallboard manufacturing process and apparatus therefor. More particularly but not exclusively it relates to an apparatus for facilitating the production of wallboard panels of increased aesthetic quality, and a method for its application in the manufacture of wallboard panels. BACKGROUND OF THE INVENTION

Wallboards or wallboard panels are produced extensively throughout the world. They are typically manufactured in a continuous manufacturing process whereby a first layer of paper is provided from a roll and moved down a production line on a conveyor belt that has a very smooth finish. A recently mixed slurry (typically consisting of calcium sulphate hemihydrate mixed with water) is then fed onto the first layer of paper as a gypsum layer, after which a second layer of paper is provided on top of the gypsum layer to form a continuous board feed. The width of the continuous board feed is then sized between rollers and is moved down the production line. As the continuous board feed moves down the production line, the gypsum slurry reacts and sets hard (as calcium sulphate dehydrate form) in a chemical reaction. The gypsum layer becomes harder the further down the production line the continuous board fed extends. At this stage, the continuous board feed is cut to produce individual wallboard panels, which are then cured in a heating process.

When the wet gypsum slurry is fed onto and/ or makes contact with the first and second paper layers, water in the slurry is absorbed by fibres in the paper layers, causing them to expand. Where the fibres in the paper are not of the same size, and/ or the paper is not of a consistent thickness, then differential expansion of the fibres in the paper can occur. Such differential expansion can cause the paper to form irregularities in the paper, in the form of localised depressions or bubbles (also called "cockles" and "canoes" in the industry). These irregularities are undesirable, as they affect the aesthetics of wallboard, which is typically expected to be smooth and regular in configuration. Where the density of individual surface irregularities is too high, this may cause the wallboard panel that is being produced to fail quality inspections. It is therefor desirable to produce smooth, flat wallboard panels without such irregularities.

In order to do so, an "ironing" process is currently known. As the continuous board feed moves down the production line on the conveyor belt, ironing bars are used to press down on the top of the continuous board feed. Ironing bars are heavy (typically metal) bars that extending transversely across the direction of feed of the production line. They are held in position in a horizontal direction, but are not constrained in a vertical direction. The weight of the bars cause the continuous board feed to be pushed down onto the conveyor belt, thereby flattening (or 'ironing") at least lower surface of the continuous board feed to provide a smooth finish with relatively less irregularities. The ironing bars provide a downward compressive force on the continuous board feed, as well as a shear force from the resultant friction of the ironing bar against the second layer of paper.

Typically, several ironing bars may be provided at intervals along the production line. However, at a certain distance down the production line, the chemical process that causes the gypsum slurry to set is at a stage where chemical bonds have been made, but where the set material is still not particularly rigid. If an ironing bar is provided to push downwardly on the continuous board feed at this stage, the forces that the ironing bar exerts on the continuous board feed can cause the newly formed chemical bonds to break. These chemical bonds may not be able to reform.

It has been found that such breaking or weakening of bonds happens commonly just underneath the surface of the second paper layer. When the continuous board feed 5000 is later cut to lengths and dried in a heated environment, the top layer 5100 is subject to increased vapour pressure from vaporised liquid in the settable layer 5300, that may cause the top layer 5100 to be pushed away and separate from the settable layer 5300. If the chemical bonds had been previously weakened or broken as explained above, this effect would be increased, with the resultant effect that when the wallboard panels are subjected to heat in the drying process, the second paper layer may come apart from the settable layer due to vapour pressure build-up under the paper layer.

In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.

For the purpose of this specification, the term "continuous board feed" is used to describe any feed of board, whether continuously or in regular lengths, where the feed comprises at least one, and preferably two, outer layers which shall include but not be limited to paper, and at least one layer of settable and/or curable matter, which shall include but not be limited to gypsum and/ or similar matter.

For the purpose of this specification, the term "effective pressure" is used to describe the real pressure equivalent of a reasonably uniformly distributed force acting over a surface area, measured in force units divided by area units.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a wallboard manufacturing process and apparatus therefor which overcomes or at least partially ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, the invention may be said to consist in a flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, the flattening apparatus comprising

• a friction minimising device that is adapted and configured for applying one or more selected from a force or pressure to said continuous board feed at a compression zone while applying a negligible frictional force to said continuous board feed.

Preferably, the friction minimising device is at least one or more fluid application apparatuses. Preferably, the friction minimising device is at least one or more fluid application apparatuses.

Preferably, the one or more fluid application apparatuses are configured for operationally applying fluid against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

Preferably, the one or more fluid application apparatuses are configured for operationally applying pressurised fluid against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

Preferably, the one or more fluid application apparatuses are configured for operationally applying pressurised fluid at high velocity against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

Preferably, the fluid application apparatuses are configured for applying fluid against the continuous board feed operationally in a manner to form a substantially frictionless layer of fluid between the flattening apparatus and the continuous board feed.

Preferably, the fluid application apparatuses are configured for applying pressurised fluid against the continuous board feed operationally in a manner to form a substantially frictionless layer of pressurised fluid between the flattening apparatus and the continuous board feed.

Preferably, the fluid application apparatus comprises one or more selected from

• a fluid inlet for receiving fluid from a fluid source;

• a fluid conduit for guiding passage of the fluid; and

• a fluid outlet for applying fluid against the top surface of said continuous board feed.

Preferably, the fluid application apparatus comprises a container for receiving fluid from the fluid inlet.

Preferably, the received fluid is from a pressurised fluid source.

Preferably, the pressurised fluid source is one or more selected from a

• compressor;

• turbine,

• pump,

• fan;

• a pressurised fluid reservoir; • or any other fluid pressurisation mechanism.

Preferably, the flattening apparatus comprises a fluid source.

Preferably, the flattening apparatus comprises the pressurised fluid source.

Preferably, the fluid application apparatus comprises a fluid pressurisation mechanism.

Preferably, the one or more fluid application apparatuses are configured for applying pressurised fluid at least partly along the width of the continuous board feed.

Preferably, the one or more fluid application apparatuses are configured for applying pressurised fluid to substantially the entire width of the continuous board feed.

Preferably, the fluid outlet is configured as one or more selected from:

• an aperture;

• a slot;

• a nozzle; and

• any other suitable configuration.

Preferably, the fluid outlet is surrounded by a compression arrangement that is configured for applying pressurised fluid over a surface area of said continuous board feed.

Preferably, the compression arrangement comprises one or more selected from

• a flat surface;

• a convex surface;

• a concave surface;

• a skirt formation; and

• a channel formation.

Preferably, the compression arrangement is configured to extend operationally over an area of the continuous board feed.

Preferably, the compression arrangement extends at least partly around the periphery of the compression zone.

Preferably, the compression arrangement extends substantially across the width of the continuous board feed.

Preferably, the compression arrangement is configured to extend substantially in parallel alignment with said continuous board feed.

Preferably, the clearance between the continuous board feed and the compression arrangement is between 0.001mm and 50mm. Preferably, the clearance between the continuous board feed and the compression arrangement is between 0.01mm and 10mm.

Preferably, the clearance between the continuous board feed and the compression arrangement is between 0.01mm and 2mm.

Preferably, the one or more fluid application apparatuses are capable of varying one or more selected from the pressure and the flow rate of the pressurised fluid.

Preferably, the compression zone extends between 1mm and 3m along the length of the conveyor belt.

Preferably, the compression zone extends between 20mm and lm along the length of the conveyor belt.

Preferably, the compression zone extends between 50mm and 0.5m along the length of the conveyor belt.

Preferably, the compression zone extends between 70mm and 150mm along the length of the continuous board feed.

Preferably, the compression zone extends about 100mm along the length of the continuous board feed.

Preferably, the fluid application apparatus comprises a body member.

Preferably, the body member is a hollow body member.

Preferably, the body member extends transversely across at least part of the width of the continuous board feed.

Preferably, the fluid outlet is defined by at least one or more apertures in the body member.

Preferably, the body member is a bar or a plate.

Preferably, the body member defines the compression arrangement.

Preferably, the friction minimising device comprises at least one or more rollers having at least one or more bearings for reducing the rolling friction of the rollers.

Preferably, the bearings are one or more selected from

• an air pressure operated bearing;

• ball bearing;

• needle bearing,

• or any other suitable bearing. Preferably, the rollers comprise a lining of spongy resilient material for distributing the downward force of the roller on the top surface of the continuous board feed.

Preferably, a plurality of rollers are provided.

Preferably, the rollers are adapted for applying a distributed force over an area of said continuous board feed at said compression zone.

Preferably, the compression zone extends at least partly along the length of the continuous board feed.

Preferably, the compression zone extends at least partly along the width of the continuous board feed.

Preferably, the compression zone extends substantially across the full width of the continuous board feed.

Preferably, the pressure exerted at the compression zone is between 0.2kPA and lOkPa.

Preferably, the pressure exerted on the compression zone is between lkPA and

7kPa.

Preferably, the pressure exerted on the compression zone is about 3.5kPa.

Preferably, the one selected from a force or pressure being exerted at the compression zone is in a downward direction.

Preferably, the flattening apparatus comprises a frame configured for locating the flattening apparatus substantially above said continuous board feed.

Preferably, the frame is configured for guiding movement of the friction minimising device.

Preferably, the frame is configured for guiding vertical movement of the friction minimising device.

Preferably, the frame comprises a guiding arrangement for guiding movement of the friction minimising device.

Preferably, the guiding arrangement is configured for restraining the friction minimising device in at least two dimensions, while allowing free movement in a third dimension.

Preferably, the guiding arrangement comprises guide slots.

Preferably, the guiding arrangement comprises guide slots for engagement with complementary guiding formations Preferably, at least part of the friction minimising device is biased towards the top surface of the continuous board feed.

Preferably, the at least part of the friction minimising device is biased towards the top surface of the continuous board feed by a weight.

Preferably, at least part of the friction minimising device is biased towards the top surface of the continuous board feed by its own weight.

Preferably, the at least part of the friction minimising device is biased towards the top surface of the continuous board feed by a resilient bias.

Preferably, the resilient bias is one selected from a spring or stretchable formation.

Preferably, the friction minimising device is securely located in position. Preferably, the flattening apparatus is configured for utilising the relative movement between the continuous board feed and the friction minimising device to entrain fluid between the friction minimising device and the continuous board feed as a frictionless layer of fluid.

Preferably, the friction minimising device comprises one or more selected from a coating and an entrainment formation suitable for facilitating the said entrainment of fluid between the continuous board feed and the friction minimising device. In another aspect, the invention may be said to consist in a method suitable for reducing surface imperfections on at least one major face of a continuous board feed in a wallboard production process; said method comprising the steps of:

• operationally applying one selected from a force and a pressure onto at least part of a continuous board feed at a compression zone to push it against a conveyor belt, while maintaining a negligible frictional force in a direction at least parallel to the direction of movement of the continuous board feed.

Preferably, the step of applying said pressure and/ or force to at least part of the continuous board feed is by applying it to a top surface of the continuous board feed to push it against a conveyor belt.

Preferably, the method comprises the step of providing a fluid.

Preferably, the method comprises the step of providing a pressurised fluid. Preferably, the method comprises the step of impinging a fluid at high velocity on to a top surface of the continuous board feed to push the continuous board feed against the conveyor belt.

Preferably, the method comprises the step of directing the fluid to form a substantially frictionless layer against the top surface of the continuous board feed.

Preferably, the method comprises the step of supporting a weight on the frictionless layer.

Preferably, the method comprises the step of pressurising the fluid.

Preferably, the method comprises the step of providing a body member. Preferably, the method comprises the step of providing body member configured for directing the pressurised fluid against the top surface of the continuous board feed as a frictionless layer.

Preferably, the body member is hollow.

Preferably, the weight of the body member is supported by the frictionless layer. Preferably, the method comprises the step of receiving pressurised fluid into a hollow member and expelling it through an outlet.

Preferably, the method comprises the step of providing a compression arrangement configured for facilitating the distribution of the pressurised fluid over a surface of the continuous board feed, and pressurising at least part of the surface of the continuous board feed at a compression zone.

Preferably, the method comprises the step of facilitating compression of the continuous board feed by directing the pressurised fluid via the compression arrangement.

Preferably, the compression arrangement is one or more selected from

• flat surface;

· a convex surface;

• a concave surface;

• a skirt formation; and

• at least one channel formation.

Preferably, the method comprises the step of utilising the relative movement between the continuous board feed and the friction minimising device to entrain fluid between the friction minimising device and the continuous board feed as a frictionless layer of fluid. Preferably, the fluid is one selected from air, an inert gas, or any other suitable gas.

Alternatively, the fluid is liquid.

Preferably, the compression arrangement facilitates the distribution of the fluid over a surface area of the continuous board feed at a compression zone as a substantially frictionless layer of pressurised fluid.

Preferably, the method comprises the steps of providing one or more rollers having relatively negligible rolling friction and engaging at least one against a major surface of the continuous board feed to apply an effective pressure to the major surface.

Preferably, the method comprises the step of providing one or more roller with a resilient soft lining and engaging it with the continuous board feed to distribute the force exerted by the rollers on the continuous board feed over an area at a compression zone as an effective pressure.

Preferably, the resilient soft covering is one or more selected from

• a sponge or sponge-like material; an

• a spongy fibrous material.

Preferably, the rollers are adapted for applying a distributed force over an area of said continuous board feed at a compression zone.

Preferably, the compression zone extends substantially across the width of the continuous board feed.

Preferably, the pressure exerted on the compression zone is between lkPA and

7kPa.

Preferably, the pressure exerted on the compression zone is about 3.5kPa.

In another aspect, the invention may be said to consist in a production line on which a continuous board feed is being fed, said production line comprising a flattening apparatus as claimed in any one of claims 1 to 54 and 81 to 82. In another aspect, the invention may be said to consist in a flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, said flattening apparatus comprising

at least one or more fluid application apparatuses configured for operationally applying pressurised fluid against a top surface of said continuous board feed in a manner to press an area of the continuous board feed towards said conveyor belt.

In another aspect, the invention may be said to consist in a flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, the flattening apparatus comprising

a friction minimising device that is configured for applying one selected form a force and a pressure to said continuous board feed without making mechanical contact with said continuous board feed, to thereby flatten at least one side of said continuous board feed.

a load distribution device that is adapted and configured for applying a uniformly distributed load downwardly over a compression zone on the said continuous board feed at a compression zone without creating localised stresses on the top surface of the continuous board feed.

Preferably, the uniform distributed load is applied to a top surface of said continuous board feed while applying a negligible frictional force to said continuous board feed.

In another aspect, the invention may be said to consist in a method suitable for reducing surface imperfections on at least one major face of a continuous board feed in a wallboard production process; said method comprising the steps of:

operationally applying a uniformly distributed load to at least part of a continuous board feed at a compression zone.

Preferably, a negligible frictional forces is maintained in a direction at least parallel to the direction of movement of the continuous board feed while the load is being distributed uniformly over the compression zone. In another aspect, the invention may be said to consist in a flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, said flattening apparatus comprising

at least one fluid bearing arrangement disposed operationally above a top surface of the continuous board feed.

Preferably, the fluid bearing arrangement is biased towards the top surface. Preferably, the fluid bearing arrangement is a hydrostatic bearing arrangement. Alternately, fluid bearing arrangement is a fluid dynamic bearing arrangement. Preferably, the fluid dynamic bearing arrangement utilises the relative velocity between a body member and the continuous board feed to entrain fluid between the body member and the continuous board feed to form a frictionless layer of fluid.

Preferably, the body member comprises one or more of a coating and an entrainment formation to facilitate the entrainment of fluid.

In another aspect, the invention may be said to consist in a wall board production process, that utilises a conveyor having a forming surface, for ensuring a laminated wall board structure that comprising of a core that is captured between two exterior paper layers has a first of said paper layers at least partially compliant to said forming surface on which it is carried (whether it is a flat surface or otherwise) said process comprising:

· directing airflow onto the other of said paper layers to force wallboard structure against said conveyor.

Preferably, the process is implemented at some stage during the curing from a non-solid phase to a solid phase of the wallboard structure.

Preferably, the process includes the advancing of the wall board structure in a linear manner, carried by said conveyor, past an airflow station from which said airflow is caused to flow onto said wallboard structure.

In another aspect, the invention may be said to consist in a method as described in this specification, with or without reference to the accompanying figures 2— 10.

In another aspect, the invention may be said to consist in a flattening apparatus as described in this specification, with or without reference to the accompanying figures 2— 10. Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

As used herein the term "and/ or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/ or singular forms of the noun.

The term "comprising" as used in this specification and claims means "consisting at least in part of. When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only and with reference to the drawings in which:

Figure 1: shows a side view of a prior art ironing bar located along a production line having a continuous board feed on it;

Figure 2: shows a side view of a first embodiment of a flattening apparatus located along a production line having a continuous board feed on it;

Figure 3: shows a side view of a second embodiment of a flattening apparatus located along a production line having a continuous board feed on it;

Figure 4: shows a side view of a third embodiment of a flattening apparatus located along a production line having a continuous board feed on it;

Figure 5a: shows a bottom view of a flattening apparatus along showing a first configuration of fluid outlets;

Figure 5a: shows a bottom view of a flattening apparatus along showing a second configuration of fluid outlets; Figure 5a: shows a bottom view of a flattening apparatus along showing a third configuration of fluid outlets;

Figure 6: shows a side cutaway view of the first embodiment of a flattening apparatus located along a production line having a continuous board feed on it;

Figure 7: shows a bottom perspective view of a body member with a skirt formation as a compression arrangement;

Figure 8: shows a bottom perspective view of an body member with a channel formations as a compression arrangement;

Figure 9: shows a side schematic view of the body member of figure 8 in operation; and

Figure 10: shows a top perspective view of a flattening apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

With reference to the above drawings, in which similar features are generally indicated by similar numerals, a flattening apparatus according to a first aspect of the invention is generally indicated by the numeral 1000, and a production line according to a further aspect of the invention is generally indicated by reference numeral 2000.

The production line 2000 comprises a conveyor belt 2100 running on rollers 2200. On a top surface 2110 of the conveyor belt 2100, a continuous board feed 5000 is provided. Such a continuous board feed 5000 may be typically found being produced on production lines where wallboard is produced. A continuous board feed 5000 may typically consist of an upper layer 5100 of paper, a lower layer 5200 of paper and an intermediate settable layer 5300 of set, setting and/ or settable slurry (e.g. such as gypsum, resin or other cementitious materials). Methods and apparatuses for production of such continuous board feeds 5000 are known and beyond the scope of this specification, and will not be discussed further.

In one embodiment now described, there is provided a flattening apparatus 1000 for flattening a continuous board feed 5000 against a conveyor belt 2100 on which the continuous board feed 5000 is being conveyed.

The flattening apparatus 1000 comprises a friction minimising device 1100 that is configured for applying a downward force and/or pressure onto a top surface 5110 of the continuous board feed. It does this while applying a negligible frictional force along the top surface 5110 of the continuous board feed 5000. In order to hold and locate the friction minimising device 1100 in place above the conveyor belt 2100, a frame 1400 is provided. In a preferred embodiment (shown in figure 2), the frame 1400 is provided with a guiding arrangement 1410 for locating and/or holding the friction minimising device 1100 in place horizontally, while allowing the friction minimising device 1100 to move freely in the vertical direction, for reasons that will be explained below.

To this end, one embodiment of a guiding arrangement 1410 is shown in figure 2. The guiding arrangement 1410 is provided for locating the friction minimising device 1100 horizontally while guiding its vertical movement vertically. The guiding arrangement 1410 shown in figure 2 comprises guide formations 1414 (which could be in the form of lugs, pins or fins or any other suitable formation) on the friction minimising device 1100 that are freely slideable in vertical guide slots 1412 on the frame 1400. Alternately, the location of the guide formations 1414 and the guide slots 1412 can be reversed. It will be appreciated that many different configurations of guiding arrangements 1410 can be provided having a similar purpose and/ or function.

An alternative embodiment of a guiding arrangement 1410 is shown in figure 10. This serves to hold the body member 1240 in two dimensions horizontally, while allowing the body member 1240 to move freely in a third dimension (the vertical direction). Additionally, the frame 1400 in this embodiment is movable (by means of pressurisable cylinders 1420) to lift the body member 1420 off the continuous board feed 5000 when required.

However, it is also envisaged that the frame 1400 can be configured and adapted to hold the friction minimising device 1100 rigidly in all three dimensions (not shown).

The friction minimising device 1100 can operate by applying a mechanical force to the top surface 5110, or it can operate by applying pressure to the top surface 5110 via a pressurised fluid. Each will be discussed below.

In one embodiment shown in figures2, 3 and 5, the friction minimising device 1100 operates by means of applying fluid pressure to the top surface 5110 via a pressurised fluid, such as compressed air. In such an embodiment the friction minimising device 1100 a pressurised fluid application device 1200. The pressurised fluid application devices 1200 is configured for operationally applying pressurised fluid against the top surface 5110 of the continuous board feed 5000 in a manner to press an area of the continuous board feed towards said conveyor belt. It is envisaged that the pressurised fluid application device 1200 will remain stationary at a point along and preferably above the conveyor belt 2100, while the continuous board feed 5000 runs past it, although this need not necessarily be the case.

Any suitable fluid could be used, including gasses such as inert gasses, or even liquids such as water or oil, subject to practical constraints, such as reactivity with the continuous board feed 5000. Where the settable material is cementitious in nature, it is conceivable that if the top and /or bottom layers 5100, 5200 of paper are wet, they may assist in the curing of the settable layer 5300.

The fluid application device 1200 applies pressurised fluid (shown as arrows A in figure 2) against the continuous board feed 5000 operationally in a manner to form a substantially frictionless layer 1210 of pressurised fluid between the friction minimising device 1100 and the continuous board feed 5000. In this way, this frictionless pressurised fluid layer acts as a fluid bearing, and the fluid application apparatus as a fluid bearing arrangement. This frictionless layer 1210 allows the fluid application device 1200 to apply a downward pressure onto top surface 5110 of the continuous board feed 5000 while applying a negligible frictional force to the top surface 5110. The vector sum of the forces applied to the top surface 5110 of the continuous board feed 5000 is therefore reduced. Further, point loading of the continuous board feed 5000 is prevented by avoiding mechanical engagement between the mechanical engagement of the pressurised fluid application device 1200 and the top surface 5110.

In prior art ironing bars, point loading can be a problem even where the ironing bar itself presents a flat surface for engagement with the top surface 5110 of the continuous board feed 5000 (as there may be undulations or peaks and troughs in the top surface 5110).

In a preferred embodiment (as shown in figure 6), the pressurised fluid application device 1200 comprises a fluid inlet 1220 for receiving pressurised fluid from a pressurised fluid source 1500 such as a compressor (not shown). The pressurised fluid application device 1200 further comprises a body member 1240, that is shown in figure 6 as a hollow member or container 1242. Pressurised fluid is fed from the fluid source 1500 through the inlet 1220 and into the hollow member or container 1240. In a preferred embodiment, the hollow member 1242 extends substantially across the full width of the conveyor belt 2100, although this need not necessarily be the case. It will be appreciate that the body member 1240 can be of a wide variety of configurations, shapes and sizes. Two different embodiments of a hollow body member 1242 are shown in figures 2 and 3. In one embodiment shown in figure 2, the hollow member 1242 is substantially elongate in shape, and substantially square in cross sectional shape. In such a case, it is envisaged that two or more, or even several such flattening apparatuses 1000 may be provided along the length of the conveyor belt 2100. In figure 3, the hollow member 1240 is a planar and extends further along the length of the conveyor belt 2100, to thereby apply pressure to the top surface 5110 of the continuous board feed 5000 for a longer length and/ or time period than the embodiment shown in figure 2.

The pressurised fluid application device 1200 further comprises one or more fluid outlets 1230 from which the pressurised fluid A is expelled from the hollow member 1240 onto the top surface 5110 of the continuous board feed 5000 to form a pressurised layer of fluid. The fluid outlet(s) 1230 can be of a wide variety of configurations and/or shapes and/ or sizes. Figures 5 a, b&c illustrates a few examples of such fluid outlets, including slots 1232 and holes 1234.

In another embodiment not shown, it is also envisaged that dedicated nozzles could be used to provide a restricted outlet for increasing the air velocity being expelled from the hollow member. Fluid expelled from the nozzles will be at high velocity (and relatively low pressure relative to the pressurised fluid). As the fluid at high velocity impinges on the top surface of the continuous board feed, it will slow and/ or stop and/ or change direction. In such a case, the fluid velocity change (as opposed to the fluid pressure itself), or inertia change, as it impinges on the continuous board feed 5000 would create a force on the top surface of the continuous board feed. It will further be appreciated that the body member 1240 need not be hollow. In another embodiment shown in figures7, 8 and 9, the fluid application apparatus 1200 comprises a body member 1240 in the form of a flat plate 1244. The flat plate 1244 has fluid conduits 1225 extending through it for supplying pressurised fluid via outlets 1230.

Where the friction minimising device 1100 is freely movable in the vertical direction, the amount of effective pressure being applied to the top surface 5110 of the continuous board feed 5000 will depend on the weight of the friction minimising device 1100. If the weight of the pressurised fluid application device 1200 is too heavy, its weight will overcome the fluid pressure, thereby pushing the pressurised fluid application device 1200 against the top surface 5110 and creating frictional forces on the top surface 5110. For this reason, the pressure of the fluid and the weight of the pressurised fluid application device 1200 must be carefully matched.

In another embodiment, it is envisaged that the friction minimising device 1100 could be biased by a dedicated resilient biasing arrangement (not shown), such as a spring (instead of or in addition to its weight) to exert a downward pressure on the continuous board feed 5000.

In another embodiment, the pressurised fluid application device 1200 could be held at a set distance above the top surface, with the pressurised fluid providing the downward pressure against the top surface 5110. It is also envisaged that the fluid pressure may be varied according to requirements (for example depending on the quality of paper being used, and the tendency of the paper to form has to form depressions, bubbles or other surface irregularities. Similarly, the weight of the pressurised fluid application device 1200 may be varied according to requirements.

It is also envisaged that in one embodiment (not shown) no container or common hollow member 1240 is required at all, and that pressurised fluid could be expelled directly from conduits (not shown) via nozzles (not shown) to apply a downward pressure in the continuous board feed 5000.

In another embodiment (not shown), it is envisaged that ambient air can be pressurised by a fluid pressurisation mechanism (not shown) such as a turbine, impeller, propeller, pump or fan before being directed onto the top surface 5110 of the continuous board feed 5000 to accomplish the same effect. In this regard, any fluid guiding vanes or the like for directing the fluid so pressurised can be regarded as being equivalent to a nozzle or fluid outlet.

As shown in figures2 and 3, in order to facilitate the provision of a layer of pressurised fluid 1210 on which the weight of the pressurised fluid application device 1200 can be supported, the outlet 1230 is surrounded by a compression arrangement 1250 that facilitates the distribution of the pressurised fluid over a compression zone 1600.

In figure 2 the compression arrangement 1250 is defined by the hollow member 1240 and configured as a flat face or surface 1252 surrounding the outlet or outlets 1230, and extending parallel to the top surface 5110 of the continuous board feed 5000 in operation. Preferably, the clearance (shown as d in figure 2) between the flat face 1252 and the top surface 5110 will be between 0.5mm and 50mm, more preferably between lmm and 20mm, even more preferably between 2mm and 20mm, and most preferably about 10mm

Further it is envisaged that the compression zone could extend between lmm and 3m along the length of the continuous board feed 5000, and most preferably about 100mm along the length of the continuous board feed 5000.

In a preferred embodiment, the compression zone 1254 extends across the full width of the continuous board feed 5000, although this need not necessarily be the case.

As shown in figure 8, a compression arrangement 1250 is provided in the form of channel formations 1254 in a lower face of the body member 1240. The channel formation 1254 are configured for distributing pressurised fluid over the compression zone 1600 reasonably uniformly. It will be appreciated that many varieties of configurations are possible and such have been widely explored in the field of both fluid bearing technology.

In another embodiment, shown in figure 7, it is envisaged that the

compression arrangement 1250 could include a skirt formation 1256 that extends around the periphery of the compression zone 1600, to facilitate the creation of a pressurised fluid layer.

It is envisaged that the compression arrangement 1250 can be configured in a wide variety of configurations, including a convex face (not shown), a concave face (not shown), a skirt formation surrounding the outlet(s) 1230 or any other suitable configuration that facilitates the application of the pressurised fluid over a surface area, in a compression zone 1254.

The examples given above are typical of hydrostatic fluid bearings. In another embodiment (not shown), the fluid application apparatus can act as a hydrodynamic fluid bearing. An example of this would be if the body member were movable in a rotational (or otherwise) manner to pressurise the surrounding air in a layer above the continuous board feed 5000. Another example of a hydrodynamic fluid bearing this would be if the movement of the continuous board feed is used to entrain fluid under the friction minimising device 1100, possibly by virtue of a coating or similar feature applied to the friction minimising device 1100.

In one embodiment (not shown), water or some other liquid can be introduced onto the top surface 5110. A friction minimising device 1100 may be held securely in position just above the continuous board feed 5000. The friction minimising device 1100 can be in the form of a planar plate held at a slightly declined angle in the direction of movement of the conveyor belt. As the water is moved under the planar plate, the cross sectional area of the space above the continuous board feed is reduced, pressurising the water, thereby causing the continuous board feed 5000 to be pushed towards the conveyor belt.

Numerous hydrodynamic principles may be used to provide such a relatively frictionless fluid However, these alternatives are not preferred, given the increased complexity of the mechanism involved.

In another embodiment shown in figures 4, the friction minimising device 1100 is envisaged as operating by means of applying a mechanical force to the top surface 5110 of the continuous board feed 5000 while reducing the frictional force as much as possible. In one such embodiment, the friction minimising device 1100 comprises a set of rollers 2200 that extend transversely across the width of the continuous board feed 5000.

The rollers 2200 are envisaged as being movable on bearings (not shown) that reduce the rolling friction of the rollers 2200. Such bearings could be air bearings (e.g. operating on air pressure), roller bearings, needle bearings or any other suitable bearing arrangement. Further, in order to reduce the point loading of the rollers 2200 on the top surface 5110, and to distribute the downward force of the roller over a larger area of the top surface 5110, it is envisaged that the rollers 2200 will have a soft resilient lining, such as sponge lining 1320 or a similar spongy or fibrous or soft resilient material disposed at an outer surface of the rollers 1300. The effect of the as sponge lining 1320 is to distribute the force exerted on the continuous board feed uniformly and evenly over a compression zone 1600 as an effective 'pressure', similar to the fluid application apparatus 1200.

It is envisaged that the rollers 1300 could be unconstrained in the vertical direction and rely on their weight or a biasing arrangement to bias the rollers against the top surface 5110 similarly to the pressurised fluid application device 1200.

In use, many flattening arrangements 1000 can be located along a conveyor belt 2100 of a production line 2000 on which a planar continuous board feed 5000 is present. The flattening arrangements 1000 are preferably provided at regular intervals along the conveyor belt 2100. As the conveyor belt 2100 passes by with the continuous board feed 5000 lying on it, each flattening arrangement 1000 applies an effective pressure and/or force onto at least one major face of the continuous board feed 5000 to push it against the conveyor belt 2100. This causes the surface of the continuous board feed 5000 that is against the conveyor belt 2100 to be flattened out, and to present desirable aesthetic characteristics. As the continuous board feed 5000 is pushed against the conveyor belt, a negligible frictional force is applied by the flattening arrangements 1000 on the continuous board feed 5000, at least in a direction parallel to the direction of movement of the continuous board feed 5000.

In the prior art systems, the ironing bars, while being flat, made physical contact with the top surface 5110 of the continuous board feed 5000. While the top surface 5110 may look flat and one would expect the force of the ironing bar to be distributed evenly over the contact area, this is not believed to be the case. Instead, it is believed that the microscopically uneven surface of the ironing bars makes contact with the surface irregularities (in the form of small to microscopic depressions and bubbles) to create localised high stress concentrations. These localised high stress concentrations can break the newly formed or forming chemical bonds in and between the settable layer 5300 and the top layer 5100, just underneath the top layer 5100 of paper.

In addition, previously frictional forces caused by the prior art ironing bars acting on the top layer 5100 may result in the destruction of newly set and setting chemical bonds between the top layer 5100 and the settable layer 5300 over the entire area of the continuous board feed 5000.

When the continuous board feed 5000 is later cut to lengths and dried in a heated environment, the top layer 5100 is subject to increased vapour pressure from vaporised liquid in the settable layer 5300, that may cause the top layer 5100 to be pushed away and separate from the settable layer 5300. If the chemical bonds had been previously weakened or broken as explained above, this effect would be increased.

By using either a spongy layer, or a layer or fluid pressure, it is hoped to evenly and uniformly distribute the weight of the ironing bar over a compression zone without creating localised high stress concentrations o create an effective 'pressure'.

By providing for a relatively frictionless layer of air, or a relatively low rolling friction roller, it is expected that frictional force acting on the top surface 5110 will be reduced.

By reducing the frictional forces acting on the top surface, it has been found that the downward forces may be increased with reduced damage to the bonds between the settable layer and the top layer. Further, point loading of the flattening arrangement 1000 on the continuous board feed 5000 is reduced, with the net effect being that the chemical bonds between the settable layer 2300 and the top layer are relatively less disturbed or damaged.

This means that the downward force can be applied to the continuous board feed 5000 for a longer distance down the conveyor belt 2100, even at a stage where the chemical bonds have been created in the settable layer 2300.

It is anticipated that the effective pressure exerted on the top surface 5110 by the flattening apparatus 1000 at the compression zone 1600 can be between 0.2kPA and lOkPa, more preferably between 1 and 7kPa and most preferably about 3.5kPa. The applicants have found that pressure equivalent to up to 3.5kPa has not resulted in destruction of the chemical bonds in setting gypsum wallboard at a distance where typically use of a prior art ironing bar has resulted in the bonds in the gypsum being damaged, causing the top paper layer to come off during subsequent drying or curing.

In this way, it is believed that the dual principles of reducing the frictional force acting on the upper surface of the continuous board feed 5000, as well as uniformly distributing the force applied to the continuous board feed and thereby reducing point loading, will allow for larger forces to be applied, and at distances further down the production line than were previously possible.

The use of the present invention has also resulted in a reduced number of irregularities and/ or cockles and/ or canoes, even where paper of relatively poor quality has been used, which would otherwise have resulted in the production of wallboard panels with an unacceptably high density of irregularities, and which would have been rejected.

In this way, it is anticipated that either reduced number of defective wallboards (or other boards) can be manufactured, or alternatively that the boards can be manufactured to current aesthetic specifications while using lower quality and/or grammage (and hence cheaper) paper.

This can translate into reduced manufacturing costs for wallboard manufacturers, and/ or reduced claims by wallboard manufacturers on their paper suppliers for the supply of inferior quality paper.

Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth. Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and/or improvements may be made without departing from the scope or spirit of the invention.

In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognise that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

CLAIMS:

1. A flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, the flattening apparatus comprising

a. a friction minimising device that is adapted and configured for applying one or more selected from a force or pressure to said continuous board feed at a compression zone while applying a negligible frictional force to said continuous board feed.

2. A flattening apparatus as claimed in claim 1 , wherein the friction minimising device is at least one or more fluid application apparatuses.

3. A flattening apparatus as claimed in claim 2, wherein the friction minimising device is at least one or more pressurised fluid application apparatuses.

4. A flattening apparatus as claimed in any of claims 2 to 3, wherein the one or more fluid application apparatuses are configured for operationally applying fluid against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

5. A flattening apparatus as claimed in claim 4, wherein the one or more fluid application apparatuses are configured for operationally applying pressurised fluid against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

6. A flattening apparatus as claimed in any of claims 2 to 5, wherein the fluid application apparatuses are configured for applying fluid against the continuous board feed operationally in a manner to form a substantially frictionless layer of fluid between the flattening apparatus and the continuous board feed.

7. A flattening apparatus as claimed in claim 6, wherein the one or more fluid application apparatuses are configured for operationally applying pressurised fluid at high velocity against a top surface of said continuous board feed in a manner to push at least part of the continuous board feed towards said conveyor belt.

8. A flattening apparatus as claimed in any one of claims 2 to 7, wherein the fluid application apparatuses are configured for applying pressurised fluid against the continuous board feed operationally in a manner to form a substantially frictionless layer of pressurised fluid between the flattening apparatus and the continuous board feed.

9. A flattening apparatus as claimed in any one of claims 2 to 8, wherein the fluid application apparatus comprises one or more selected from:

a. a fluid inlet for receiving fluid from a fluid source;

b. a fluid conduit for guiding passage of the fluid; and

c. a fluid outlet for applying pressurised fluid against the top surface of said continuous board feed.

10. A flattening apparatus as claimed in any one of claims 2 to 9, wherein the fluid application apparatus comprises a container for receiving fluid from the fluid inlet.

11. A flattening apparatus as claimed in claim 10, wherein the received fluid is from a pressurised fluid source.

12. A flattening apparatus as claimed in claim 11, wherein the pressurised fluid source is one or more selected from a

a. compressor;

b. turbine,

c. pump,

d. fan;

e. a pressurised fluid reservoir;

f. or any other fluid pressurisation mechanism.

13. A flattening apparatus as claimed in any one of claims 1 to 12, further comprising a fluid source

14. A flattening apparatus as claimed in claim 13, wherein the fluid source is a pressurised fluid source.

15. A flattening apparatus as claimed in any one of claims 2 to 14, wherein the fluid application apparatus comprises a fluid pressurisation mechanism.

16. A flattening apparatus as claimed in any one of claims 2 to 15, wherein the one or more fluid application apparatuses are configured for applying fluid at least partly along the width of the continuous board feed.

17. A flattening apparatus as claimed in claim 16, wherein the one or more fluid application apparatuses are configured for applying fluid to substantially the entire width of the continuous board feed.

18. A flattening apparatus as claimed in any one of claims 9 to 17, wherein the fluid outlet is configured as one or more selected from:

a. an aperture; b. a slot;

c. a nozzle; and

d. any other suitable configuration.

19. A flattening apparatus as claimed in any one of claims 9 to 18, wherein the fluid outlet is surrounded by a compression arrangement that is configured for applying the pressurised fluid over a surface area of said continuous board feed.

20. A flattening apparatus as claimed in claim 19, wherein the compression arrangement comprises one or more selected from

a. a flat surface;

b. a convex surface;

c. a concave surface;

d. a skirt formation; and

e. a channel formation

21. A flattening apparatus as claimed in any one of claims 19 to 20, wherein the compression arrangement is configured to extend operationally over an area of the continuous board feed.

22. A flattening apparatus as claimed in any one of claims 19 to 21, wherein the compression arrangement extends at least partly around the periphery of the compression zone.

23. A flattening apparatus as claimed in any one of claims 19 to 22, wherein the compression arrangement extends substantially across the width of the continuous board feed.

24. A flattening apparatus as claimed in any one of claims 19 to 23, wherein the compression arrangement is configured to extend substantially in parallel alignment with said continuous board feed.

25. A flattening apparatus as claimed in any one of claims 19 to 24, wherein the clearance between the continuous board feed and the compression arrangement is between 0.001mm and 50mm.

26. A flattening apparatus as claimed in claim 25, wherein the clearance between the continuous board feed and the compression arrangement is between 0.01mm and 10mm.

27. A flattening apparatus as claimed in claim 26, wherein the clearance between the continuous board feed and the compression arrangement is between 0.01mm and 2mm.

28. A flattening apparatus as claimed in any one of claims 2 to 27, wherein the one or more fluid application apparatuses are capable of varying one or more selected from the pressure and the flow rate of the fluid.

29. A flattening apparatus as claimed in any one of claims 19 to 28, wherein the compression zone extends between 1mm and 3m along the length of the conveyor belt.

30. A flattening apparatus as claimed in claim 29, wherein the compression zone extends between 20mm and lm along the length of the conveyor belt.

31. A flattening apparatus as claimed in claim 30, wherein the compression zone extends between 50mm and 0.5m along the length of the conveyor belt.

32. A flattening apparatus as claimed in claim 31, wherein the compression zone extends between 70mm and 150mm along the length of the conveyor belt.

33. A flattening apparatus as claimed in claim 32, wherein the compression zone extends about 100mm along the length of the conveyor belt.

34. A flattening apparatus as claimed in any one of claims 2 to 33, wherein the fluid application apparatus comprises a body member.

35. A flattening apparatus as claimed in claim 34, wherein the body member is a hollow body member.

36. A flattening apparatus as claimed in any one of claims 34 to 35, wherein the body member extends transversely across at least part of the width of the continuous board feed.

37. A flattening apparatus as claimed in any one of claims 34 to 36, wherein the fluid outlet is defined by at least one or more apertures in the body member.

38. A flattening apparatus as claimed in any one of claims 34 to 37, wherein the body member is a bar or a plate.

39. A flattening apparatus as claimed in any one of claims 34 to 38, wherein the body member defines the compression arrangement.

40. A flattening apparatus as claimed in claim 1, wherein the friction minimising device comprises at least one or more rollers having at least one or more bearings for reducing the rolling friction of the rollers.

41. A flattening apparatus as claimed claim 40, wherein the bearings are one or more selected from

a. an air pressure operated bearing;

b. ball bearing;

c. needle bearing, d. or any other suitable bearing.

42. A flattening apparatus as claimed in any one of claims 40 to 41, wherein the rollers comprise a lining of spongy resilient material for distributing the downward force of the roller on the top surface of the continuous board feed.

43. A flattening apparatus as claimed in any one of claims 40 to 42, wherein a plurality of rollers are provided.

44. A flattening apparatus as claimed in any one of claims 40 to 43, wherein the rollers are adapted for applying a distributed force over an area of said continuous board feed at said compression zone.

45. A flattening apparatus as claimed in any one of claims 1 to 44, wherein the compression zone extends at least partly along the length of the continuous board feed.

46. A flattening apparatus as claimed in any one of claims 1 to 45, wherein the compression zone extends at least partly along the width of the continuous board feed.

47. A flattening apparatus as claimed in claim 46, wherein the compression zone extends substantially across the full width of the continuous board feed.

48. A flattening apparatus as claimed in any one of claims 1 to 47, wherein the pressure exerted at the compression zone is between 0.0.2kPA and lOkPa.

49. A flattening apparatus as claimed in claim 48, wherein the pressure exerted on the compression zone is between lkPA and 7kPa.

50. A flattening apparatus as claimed in claim 49, wherein the pressure exerted on the compression zone is about 3.5kPa.

51. A flattening apparatus as claimed in any one of claims 1 to 50, wherein the one selected from a force or pressure being exerted at the compression zone is in a downward direction.

52. A flattening apparatus as claimed in any one of claims 1 to 51, wherein the flattening apparatus comprises a frame configured for locating the flattening apparatus substantially above said continuous board feed.

53. A flattening apparatus as claimed in claim 52, wherein the frame is configured for guiding movement of the friction minimising device.

54. A flattening apparatus as claimed in claim 53, wherein the frame is configured for guiding vertical movement of the friction minimising device.

55. A flattening apparatus as claimed in any one of claims 52 to 54, wherein the frame comprises a guiding arrangement for guiding movement of the friction minimising device.

56. A flattening apparatus as claimed in claim 55, wherein the guiding arrangement is configured for restraining the friction minimising device in at least two dimensions, while allowing free movement in a third dimension.

57. A flattening apparatus as claimed in any of claims 55 to 56, wherein the guiding arrangement comprises guide slots.

58. A flattening apparatus as claimed in claim 55, wherein the guide slots are for engagement with complementary guiding formations

59. A flattening apparatus as claimed in any one of claims 1 to 58, wherein at least part of the friction minimising device is biased towards the top surface of the continuous board feed.

60. A flattening apparatus as claimed in claim 59, wherein the at least part of the friction minimising device is biased towards the top surface of the continuous board feed by a weight.

61. A flattening apparatus as claimed in any claims 60, wherein the, at least part of the friction minimising device is biased towards the top surface of the continuous board feed by its own weight.

62. A flattening apparatus as claimed in any one of claims 59 to 61, wherein the at least part of the friction minimising device is biased towards the top surface of the continuous board feed by a resilient bias.

63. A flattening apparatus as claimed in claim 62, wherein the resilient bias is one selected from a spring and an elastically stretchable formation.

64. A flattening apparatus as claimed in any one of claims 1 to 63, wherein the friction minimising device is securely located in position.

65. A flattening apparatus as claimed in any one of claims 1 to 63, wherein the flattening apparatus is configured for utilising the relative movement between the continuous board feed and the friction minimising device to entrain fluid between the friction minimising device and the continuous board feed as a frictionless layer of fluid.

66. A flattening apparatus as claimed in claim 59, wherein the friction minimising device comprises one or more selected from a coating and an entrainment formation suitable for facilitating the said entrainment of fluid between the continuous board feed and the friction minimising device.

67. A method suitable for reducing surface imperfections on at least one major face of a continuous board feed in a wallboard production process; said method comprising the steps of:

a. operationally applying one selected from a force and a pressure onto at least part of a continuous board feed at a compression zone to push it against a conveyor belt, preferably while maintaining a negligible frictional forces in a direction at least parallel to the direction of movement of the continuous board feed.

68. A method as claimed in claim 67, wherein the step of applying said pressure and/ or force to at least part of the continuous board feed is by applying it to a top surface of the continuous board feed to push it against a conveyor belt.

69. A method as claimed in any of claims 67 to 68, wherein the method comprises the step of providing a fluid.

70. A method as claimed in any claims 69, wherein the method comprises the step of providing a pressurised fluid.

71. A method as claimed in any of claims 69 to 70, wherein the method comprises the step of impinging a fluid at high velocity onto a top surface of the continuous board feed to push the continuous board feed against a conveyor belt.

72. A method as claimed in any of claims 69 to 71, wherein the method comprises the step of directing the fluid to form a substantially frictionless layer against the top surface of the continuous board feed.

73. A method as claimed in claim 72, wherein the method comprises the step of supporting a weight on the frictionless layer

74. A method as claimed in any of claims 69 to 73, wherein the method comprises the step of pressurising the fluid.

75. A method as claimed in any of claims 67 to 74, wherein the method comprises the step of providing a body member.

76. A method as claimed in claim 75, wherein the body member is configured for directing the fluid against the top surface of the continuous board feed as a frictionless layer.

77. A method as claimed in any of claims 75 to 76, wherein the body member is hollow.

78. A method as claimed in any of claims 75 to 77, wherein the weight of the body member is supported by the frictionless layer.

79. A method as claimed in any of claims 70 to 78, wherein the method comprises the step of receiving pressurised fluid into a hollow member and expelling it through an outlet.

80. A method as claimed in any of claims 69 to 79, wherein the method comprises the step of providing a compression arrangement configured for facilitating the distribution of fluid over a surface of the continuous board feed, and pressurising at least part of the surface of the continuous board feed at a compression zone.

81. A method as claimed in claim 80, wherein the method comprises the step of facilitating compression of the continuous board feed by directing the pressurised fluid via the compression arrangement.

82. A method as claimed in any of claims 80 to 81, wherein the compression arrangement is one or more selected from

a. flat surface;

b. a convex surface;

c. a concave surface;

d. a skirt formation; and

e. at least one channel formation.

83. A method as claimed in any of claims 75 to 79, wherein the method comprises the step of utilising the relative movement between the continuous board feed and the body member to entrain fluid between the friction minimising device and the continuous board feed as a frictionless layer of fluid to apply one selected from a force and a pressure onto at least part of a continuous board feed at a compression zone.

84. A method as claimed in any of claims 69 to 83, wherein the fluid is one selected from air, an inert gas, or any other suitable gas.

85. A method as claimed in any of claims 58 to 56, wherein the fluid is liquid.

86. A method as claimed in any one of claims 80 to 85, wherein the compression arrangement facilitates the distribution of the fluid over a surface area of the continuous board feed at a compression zone as a frictionless layer of pressurised fluid.

87. A method as claimed in any of claims 72-86, wherein the method comprises the step of supporting a weight on the frictionless layer of pressurised fluid.

88. A method as claimed in any of claims 67 to 87, wherein the method comprises the steps of providing one or more rollers having relatively negligible rolling friction and engaging at least one against a major surface of the continuous board feed to apply an effective pressure to the major surface.

89. A method as claimed in claim 88, wherein the method comprises the step of providing one or more roller with a resilient soft lining and engaging it with the continuous board feed to distribute the force exerted by the rollers on the continuous board feed over an area at a compression zone as an effective pressure.

90. A method as claimed in claim 89, wherein the resilient soft covering is one or more selected from

a. a sponge or sponge-like material; an

b. a spongy fibrous material.

91. A method as claimed in any of claims 88 to 90, wherein the rollers are adapted for applying a distributed force over an area of said continuous board feed at a compression zone.

92. A method as claimed in any of claims 67 to 91, wherein the compression zone extends at least partly along the length of the continuous board feed.

93. A method as claimed in any of claims 67 to 92, wherein the compression zone extends at least partly along the width of the continuous board feed.

94. A method as claimed in claim 93, wherein the compression zone extends substantially across the width of the continuous board feed.

95. A method as claimed in any of claims 67 to 94, wherein the pressure or effective pressure exerted on the compression zone is between 0.2kPA and lOkPa.

96. A method as claimed in claim 95, wherein the pressure exerted on the compression zone is between lkPA and 7kPa.

97. A method as claimed in claim 9, wherein the pressure exerted on the compression zone is about 3.5kPa.

98. A production line on which a continuous board feed is being fed, said production line comprising a flattening apparatus as claimed in any one of claims a. 1 to 66;

b. 100 to 102; and

c. 105 to 110

99. A flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, said flattening apparatus comprising a. at least one or more fluid application apparatuses configured for operationally applying fluid against a top surface of said continuous board feed in a manner to press an area of the continuous board feed towards said conveyor belt.

100. A flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, the flattening apparatus comprising

a. a friction minimising device that is configured for applying one selected form a force and a pressure to said continuous board feed without making mechanical contact with said continuous board feed, to thereby flatten at least one side of said continuous board feed.

101. A flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, the flattening apparatus comprising

a. a load distribution device that is adapted and configured for applying a uniformly distributed load downwardly over a compression zone on the said continuous board feed at a compression zone without creating localised stresses on the top surface of the continuous board feed.

102. A flattening apparatus as claimed in claim 101, wherein the uniform distributed load is applied to a top surface of said continuous board feed while applying a negligible frictional force to said continuous board feed.

103. A method suitable for reducing surface imperfections on at least one major face of a continuous board feed in a wallboard production process; said method comprising the steps of:

a. operationally applying a uniformly distributed load to at least part of a continuous board feed at a compression zone.

104. A method as claimed in claim 103, wherein a negligible frictional forces is maintained in a direction at least parallel to the direction of movement of the continuous board feed while the load is being distributed uniformly over the compression zone.

105. A flattening apparatus for flattening a continuous board feed on a wallboard panel production line onto a conveyor belt, said flattening apparatus comprising

a. at least one fluid bearing arrangement disposed operationally above a top surface of the continuous board feed.

106. A flattening apparatus as claimed in claim 105, wherein the fluid bearing arrangement is biased towards the top surface.

107. A flattening apparatus as claimed in any one of claims 105 to 106, wherein the fluid bearing arrangement is a hydrostatic bearing arrangement.

108. A flattening apparatus as claimed in any one of claims 105 to 106, wherein the fluid bearing arrangement is a fluid dynamic bearing arrangement.

109. A flattening apparatus as claimed in claim 108, wherein the fluid dynamic bearing arrangement utilises the relative velocity between a body member and the continuous board feed to entrain fluid between the body member and the continuous board feed to form a frictionless layer of fluid.

110. A flattening apparatus as claimed in claim 109, wherein the body member comprises one or more of a coating and an entrainment formation to facilitate the entrainment of fluid.

111. A wall board production process, that utilises a conveyor having a forming surface, for ensuring a laminated wall board structure that comprising of a core that is captured between two exterior paper layers has a first of said paper layers at least partially compliant to said forming surface on which it is carried (whether it is a flat surface or otherwise) said process comprising:

a. directing airflow onto the other of said paper layers to force wallboard structure against said conveyor.

112. A process as claimed in claim 111, wherein the process is implemented at some stage during the curing from a non-solid phase to a solid phase of the wallboard structure.

113. A process as claimed in any one of claims 111 to 112, wherein the process includes the advancing of the wall board structure in a linear manner, carried by said conveyor, past an airflow station from which said airflow is caused to flow onto said wallboard structure.