WO2006030167A1

WO2006030167A1 - Improved conveyance belt and method of designing same

Info

Publication number: WO2006030167A1
Application number: PCT/GB2004/003878
Authority: WO
Inventors: James Christopher; Peter Sadd
Original assignee: Rhm Technologies
Priority date: 2004-09-13
Filing date: 2004-09-13
Publication date: 2006-03-23

Abstract

The present invention relates to belts (1) for carrying sticky material (3) and methods for designing the same, and is particularly but not exclusively related to belts for transporting “wet” dough mixtures in bakeries. In one aspect the present invention provides modular conveyance belt links (21) for transporting sticky material (3) such as wet bread dough mixtures. The links can be coupled to other links to form a belt for conveying the sticky material. The links have a conveying surface which has surface features comprising a number of closed cell structures (12) such as diamond shaped imprints. Raised ridges (13) are arranged to enclose a number of depressed areas (14) or imprints corresponding to the closed cells (12) her aspect the present invention provides a method of testing shapes and patterns of shapes for a plurality of closed cells having raised edges on a conveyance belt in order to reduce the peel resistance of a sticky material being removed from said belt.

Description

Improved Conveyance Belt and Method of Designing Same

Field of the Invention

The present invention relates to belts for carrying sticky material and methods for designing the same, and is particularly but not exclusively related to belts for transporting "wet" dough mixtures in bread bakeries.

Background of the Invention

The handling of "wet" dough mixtures is an important consideration in bakeries where bread and similar produce is prepared. The mixed dough needs to be transported from mixing vats and the like to ovens for baking, as well as to cutting and shaping processes, and resting conveyors which provide a dwell time in order to relax the dough. However the dough mixture is typically sticky and inclined to stick to whatever surface it finds itself on. This problem is exacerbated when the surface contains small gaps into which the dough can flow. A build-up of dough mixture in these gaps as well as on the surfaces themselves leads to performance issues and requires maintenance to rectify. The build-up of dough debris can also lead to hygiene problems, increasing the need for regular maintenance, however such maintenance breaks in production affect the efficiency of the bakery.

Continuous or endless belts are used to transport the wet dough from one process to another. In order to reduce the peel-off resistance of the sticky material, the surface of the belts are typically comprised of felt or similar point contact materials which incorporate air. Thus the sticky material rests on a series of point contacts rather than a large flat surface. This reduces its propensity to stick to the surface, and hence its peel- off resistance. Whilst the peel-off resistance at the end of the material's travel on the belt is important, it is also important that the material can be easily removed from the belt from any direction (not just against the direction of travel). This is to aid tolerance to stoppages, particularly following a breakdown during which a build-up of sticky material might dry onto the belt requiring maintenance. Felt surfaces are well suited in this regard, because they are reasonably "isotropic" in terms of their peel-off resistance, this being reasonably uniform with the direction of peel-off. The resistance is also reasonably uniform over a length of belt resulting in less tugging of the material and hence reducing the likelihood of tearing of the material and sticking. A problem with felt belts, however, is that they are increasingly regarded as unhygienic, with dough and other material accumulating between their fibres.

To tackle this hygiene problem, plastic belt surfaces have been used with projections to imitate the point contact nature of felt belts. The projections are typically pyramids covering the belt surface. Whilst this does address the hygiene concerns, it still results in unacceptably high peel-off resistance and/or lack of uniformity of such resistance increasing the likelihood of problematic sticking and hence reducing system performance and hindering maintenance of the belts.

Summary of the Invention

In general terms, in one aspect the present invention provides modular conveyance belt links or modules for transporting sticky material such as wet bread dough mixtures. The links can be coupled to other links to form a belt for conveying the sticky material. The links have a conveying or working surface which has surface features comprising a number of closed cell structures such as inverted pyramid imprints which are defined as truncated inverted pyramid indents arranged into diamond or square patterns for example. Raised ridges are arranged to enclose a number of depressed areas or imprints corresponding to the closed cells.

The links also comprise tabs or keyways which extend from the main working surface in directions parallel to the direction of travel of the belt. These tabs form gaps therebetween which correspond to tabs from an adjacent link, in order that when coupled together, the tabs of one link interlink with the tabs of the other link to form a continuation of the working surface.

The use of these types of closed cells in interlinked modular belts reduces the peel-off resistance of the sticky material, and also reduces the variation in peel-off resistance over the belt surface, thereby reducing the likelihood that some of the material will stick to the belt. It also aids cleaning during which some material may need to be peeled off the belt surfaces from various directions. Further the modular nature of the belt also aids maintenance and installation of these belts.

By incorporating these cells on the tabs, and having interlocking tabs with minimal gaps, release of sticky material from these belts is greatly facilitated.

Preferably the tabs or keyways are formed integrally with the rest of the working surface of the link. This further reduces the gap area on the working surface.

Modular belts are easier to make and break than continuous belts, they also have a longer working life and are less prone to edge fraying. This is due to the rugged material from which they can be made, which because of the hinges or links in their structure allows for bending around end rollers and the like. Continuous belts however need to be made from a flexible material which itself is capable of being bent around a roller. The material of modular belts can also readily have metal or other detectable material added. This allows for the detection of broken belt material in the dough. A further advantage of modular belts is improved tracking over the path of the belt.

The terms modular and continuous belts are defined here for the purposes of this specification. Modular belts comprise a plurality of modules or links which are joined or hinged together to form a loop belt which can bend around rollers by virtue of these joins or hinges. A continuous belt is made from a single item of material and is either formed or joined at the ends to form a loop belt. Its flexibility around rollers is therefore dependent on the flexibility of its material. The closed cells provide a ''cushion" of air which assists in holding up the sticky mixture but does not contribute to retention of the material to the belt surfaces. The use of these closed cells also minimises contact area with the sticky material which is only in contact with the tops of the ridges.

In particular the present invention provides a modular conveyance belt for conveying a sticky material, the belt modules comprising a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges. The belt further comprises one or more tabs or projections extending the conveying surface and adapted to interlink with corresponding tabs from adjacent modules in order to form a substantially gap free conveying surface.

The closed cells may simply consist of the ridges and the surface of the belt, although other arrangements are possible, for example, sloping ridges leading to a depressed area within the cells of varying height above the belt surface.

Preferably the profile of the cells is such as to increase their surface area; for example by having a stunted projection in the middle of the cells or having an undulating or jagged bottom surface. This allows additional moisture from the sticky material to condense on these surfaces thus further reducing the stickiness of the material and hence its peel resistance. Such complex profiles could be applied to continuous as well as to modular belts.

Preferably the closed cells are provided over substantially the whole of the belt surface in contact with the sticky material. The belt links will include interlocking edges comprising alternate tab projections or tongues and recesses to receive the tabs from other links. Preferably the closed cells are also provided over the surface of the tabs .

Preferably the closed cells are shaped such that the peel resistance of the sticky material is minimised and substantially uniform when peeling in opposition to the direction of travel of the conveying surface. Preferably the cells are shaped such that the peel resistance of the sticky material is minimised and substantially uniform when peeling from any direction.

Preferably the closed cells are pyramid shaped in a plane parallel to the plane of the conveying surface. Preferably the pyramid shaped cells are arranged such that a line drawn through two opposite corners of the diamond is parallel to the direction of travel of the conveying surface.

Alternatively the closed cells have an irregular shape, especially a rough or fragmented shape such as a fractal for example, with cells which are all of comparable size.

The cells may have the same shape across the belt, or cells of different shapes may be applied to the belt surface, in repeating patterns or non-repeating layouts.

There is also provided a method of conveying sticky material using a conveyance belt comprising a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges.

In general terms in another aspect the present invention provides a conveyance belt for conveying a sticky material, the belt comprising a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges, wherein the closed cells have a fractured or fragmented shape. These could alternatively be defined as non-geometrical shapes. An example is a fractal.

These irregular shapes improve the peeling properties of the belts in terms of peak peeling resistance and/or uniformity of peeling resistance. It is desirable that there should be now alignment of the walls of cells that are relatively close together (i.e. within 5 cells). In addition, cells where the cells have acute angles are undesirable as the corner may act as a trap point for dough. These irregular shapes could be used on both continuous and modular belts.

hi general terms in another aspect the present invention provides a conveyance belt for conveying a sticky material, the belt comprising a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges, wherein the closed cells have different shapes across the belt.

The use of repeating or non-repeating patterns of shaped cells improves the peeling properties of the belts in terms of peak peeling resistance and/or uniformity of peeling resistance. These irregular patterns of shapes could be used on both continuous and modular belts.

In general terms in another aspect the present invention provides a method of testing shapes and patterns of shapes of a plurality of closed cells having raised edges on a conveyance belt in order to determine whether these are suitable for conveying sticky materials which must be removed from said belt.

This allows different patterns of cells to be tested for suitability for belts for transporting sticky materials such as bread dough. This suitability may depend on the peel-off resistance between the belt and material, as well as its variability. It may also depend on how symmetric or isotropic these characteristics of the peel resistance are. For example a low variability of peel resistance may be desirable in any direction, in order to assist not just removing the material from the end of the belt, but also from other parts of the belt from different directions in order to facilitate cleaning and maintenance of the belt. Additionally, it has been observed that patterns having isotropic peeling characteristics improve normal end peeling.

In an embodiment this can be achieved by determining a series of parameters corresponding to the peel resistances of the sticky material over a section and preferably sections running over different directions of the belt. Preferably the variation of the parameters over the sections is also determined. This provides a performance profile of the belt in terms of its resistance to the removal of sticky materials. By setting certain constraints on the profile, suitable patterns of closed cells can be identified. Thus for example in some applications it may be desirable to have a pattern of closed cells in which the variance of the peel resistance is below a certain threshold for all directions.

Suitability may be determined by generating a graph for manual inspection, or by providing the above mentioned constraints and allowing a computer system for example to determine suitability, perhaps providing a number of candidate patterns which can then be further assessed, for example with respect to production cost of corresponding belts.

In an embodiment, the parameter is the density of the ridges over a series of scan lines over the pattern. The amount of ridge or wall exposed to a "front" of peeling material being a good indicator of the likely resistance to its removal. The variance is preferably the standard deviation.

hi particular the present invention provides a method of testing the peeling performance of a conveyance belt module from which a sticky material is to be removed and which has a plurality of closed cells formed by patterns of ridges on the conveying surface of the belt; the method comprising: determining a series of parameters corresponding to the peel resistances of the sticky material over a section of said belt; determining the variation of said parameter over said section.

In general terms in another aspect the present invention provides a method of determining a shape for a plurality of closed cells having raised edges on a conveyance belt in order to reduce the peel resistance of a sticky material being removed from said belt.

This may be achieved by randomly generating candidate patterns of cell shapes and testing them using the above defined method. There are also provided belts made according to the above defined methods. Additionally there is provided dough having an imprinted pattern corresponding to the closed cell structure of the above defined belts.

Improved peeling characteristics such as lower peak peeling resistance and uniformity has a number of advantages within the bread making industry. It allows for higher water additions to the dough, which reduces the unit cost of bread and also facilitates special moulding of the dough due to its reduced viscosity. The use of additional water in the dough reduces the amount of flour required to make the equivalent weight of bread. Without the improved peeling properties of belts of the embodiments, this increased water would lead to greater sticking and the associated problems mentioned above.

Reduced sticking also leads to less waste of materials, and also the labour required for removing dough residues, and if necessary rectifying jams and cleaning.

Brief Description of the Drawings

Embodiments will now be described with reference to the following drawings, by way of example only and without intending to be limiting, in which:

Figure 1 shows a conveyer belt transporting a sticky material;

Figure 2 shows a closed cell surface pattern applied to a conveyer belt;

Figure 3 a shows two links or modules from a modular belt, and figure 3b shows a detail from two adjacent tabs;

Figure 4a and 4b show different section profiles for a closed cell;

Figure 5a and 5c show respectively a diamond and rectangle closed cell shape, and figures 5b and 5d show the peel resistance resulting from these shapes respectively; Figures 6a - 6h show closed cell surface patterns and corresponding graphs showing their peel-off resistance variability with direction;

Figure 7 shows a method of testing patterns of closed cell shapes for use on a conveyer belt, and

Figures 8a and 8b show respectively scanning of a pattern and its representation as a 2D array.

Detailed Description

Referring first to figure 1 , a conveyor belt arrangement for transporting a sticky "wet" dough mixture is shown. The arrangement comprises a continuous belt or loop 1 which is mounted on rollers and has a top or working path which is arranged to receive the mixture or sticky material 3. The sticky material 3 is transported in the direction T by the belt. At the "end" of the belt 1, the material 3 must be removed, for example to pass onto another belt, or baking tray or similar. Because of the stickiness of the material 3, there will be a tendency for it to stick to the belt 1.

In order to minimise this tendency, felt belts having multiple small contact points have typically been used. However in order to improve hygiene, plastic coated belts having ridges or projections have also been used in order to reduce the contact area. Various shapes have been used for the projections, including squares, cylinders and hooks. Pyramid shaped projections 2 are shown in the detail of the belt surface in figure 1. Whilst this may be an improvement over a flat belt having a featureless surface, there is still significant peel-off resistance and/or variation in peel-off resistance when trying to separate the mixture 3 from a belt having these types of projections.

Figure 2 shows a pattern of closed cell surface structures on a conveyor belt for transporting sticky material. The belt 11 comprises a series of ridges 13 raised above the normal belt surface, and which enclose areas of normal belt surface or otherwise "depressed" areas 14 in order to form the closed cells 12. The sticky material carried by the belt 11 comes into contact with the ridges 13 but not the imprints or depressions 14 which reduces the contact area of the belt exposed to the material. The closed cells retain air which helps cushion the sticky material to prevent it touching the bottom of the depression 14. This type of closed cell arrangement has been found to be superior to the surface projections arrangement of figure 1 in terms of reducing peel-off resistance and improving its uniformity.

Figure 3 shows a link or module 21 from a modular belt also used for transporting sticky materials. Modular belts are well suited to maintenance and cleaning operations, but have previously not been used for the transport of sticky materials. The belts include edges having alternate tabs or keyways 25 and recesses 26 which fit into corresponding recesses and tabs in adjacent belt modules. The modules are secured by one of many known hinge arrangements, and they utilise an inter-digitating or interlocking arrangement of tabs as shown to minimise the gaps between the modules.

It has been thought that gaps between the belt modules 21 would attract and retain the sticky material and make cleaning and maintenance required more often. Against these expectations however, the use of inter-digitated keyways and closed cell structures 22 on the adjacent belt modules 21 forming a modular belt has been shown to work well in practice by the inventors; with sticky material being retained by the belt at acceptably low levels. This is especially the case where the pattern of closed cells is extended onto the tabs 25 of the modules 21.

Preferably the gaps between the keyways 25 are made as small as possible, and are arranged to effectively "seal" the belt when flat. This is facilitated by tight hinges and minimising the number of keyways 25 per belt module. Preferably the number of keyways ranges from 1 to 18, and more preferably from 3 to 10 for a 300mm wide belt. Preferably the gap widths are between 0.1 and 5mm, but more preferably less than 0.25mm.

Preferably the arrangement of cells at the edges of the belt modules, and particularly at the edges of the keyways is such as to avoid fractional (other than half) cells. Ideally full or whole cells should be included at the edges, although half cells (preferably incorporating walls so as to remain closed) could be used as shown in figure 3b.

Pyramid cells of the type shown and as aligned have been found to provide a level and uniformity of peel-off resistance that allows modular belts to be used successfully for the transport of sticky material. The size of the cells is not to scale, and in practice cells of the order of 2mm in pitch (that is the distance between cells in the direction of travel) are suitable. A size of 1.5mm pitch has also been found to work well. However it is expected that cell sizes too small will trap dough debris and cell sizes too large will allow the dough to flow into the cells and increase sticking. Of course other shapes and/or sizes have also been found suitable, and so the question of what patterns of cells are suitable has also been addressed by the inventors. This is described in more detail below.

Referring now to figure 4a, a cross-section AA is shown through the surface pattern of figure 2. The section is a simple construction having ridge walls 13 extending perpendicular from the belt surface, and due to their intersecting pattern forming the closed cells having a depression 14 which falls to the belt surface as shown.

Figure 4b shows an alternative cross-section in which the depression 14' incorporates an undulating form having a raised portion in the middle of the depression 14'. Various other alternative cross-sectional arrangements could also be used; for example jagged or irregular bottom surface, as well as more complex ridge wall constructions. Also as shown in figure 4b, and top of the ridges may be shaped to improve peeling properties, for example to have a rounded top as shown.

The additional surface area of the resulting cell provides for greater condensation of moisture from the sticky material onto the surface of the cell 12. This dries part of the mixture at its contact point with the cell ridge walls 13, reducing its adherence and hence improving the peel-off performance of the belt.

The pattern of closed cells applied to a belt surface is advantageously combined with a modular belt which both reduces the retention of sticky material to the belt whist also making maintenance and cleaning of the belt easier when this is required. The closed pattern of cells with the alternative cross section 14' could additionally be used with continuous belts.

The material of the belt surface can also affect the peeling properties of the belt, and it has been found that a matt finish is preferable to a gloss finish, although the later is still well suited to these applications.

Referring now to figure 5, two cell shapes are shown together with the direction of travel T of the belt. Figure 5a shows a diamond shaped cell and figure 5c a rectangular shaped cell. The arrows R indicate the peel-off direction of the sticky material at the end of the belt. Figure 5b shows the peel-off force F required to separate the dough from the belt over time (t) or distance (d) of the belt. As can be imagined and as is shown in figure 5b, the peel-off resistance or force F is relatively constant over the cell as the ridges, where the material is in contact, are angled compared with the direction of travel, and therefore the amount of ridge or wall in contact with the peeling dough remains reasonably constant. By contrast, in figures 5c and 5d, the material encounters two edges perpendicular to the direction of travel and more or less very little resistance in between. This results in periodic tugging of the material off the belt compared with a smoother pulling with the arrangement of figure 5 a. The tugging is more likely to result in tearing of part of the material and hence some retention by the belt. The more uniform resistance of the pyramid shape suitably aligned with the direction of travel results in improved peel-off performance.

Peel-off resistance is important opposing the direction of travel as this is the way the vast majority of sticky material is separated from the belt, however it is also important from other directions particularly for maintenance and cleaning purposes. Various shapes of closed cells can be applied to the belt surface in order to reduce peel-off resistance in one or more directions. Ideally peel-off resistance should be below a certain minimum threshold in all directions and/or within a uniform range over that direction in order to aid performance of the conveyer belt arrangement, for example to increase its speed, as well as to assist with maintenance. Figures 6a - 6h show four different cell patterns (a, c, e, g) and corresponding graphs (b, d, f, h) showing the variation in peel-off resistance verses angle (compared with direction of travel). The variation in resistance will be higher if over a section of the belt the resistance is low at some points and much higher at others, and particularly if this varies rapidly. This is problematic as a low resistance followed abruptly by a high resistance will result in tugging of the sticky material and increase the risk of tearing it and the torn part sticking to the belt. A low variation in resistance, even if perhaps higher on average than other patterns with more variation is less likely to result in sticking, at least for some materials.

For improved maintenance and cleaning, and more generally for improved release, it is important for the peeling performance of a belt (i.e. its peel resistance and or uniformity) to be favourable in all or most directions, not just against the direction of travel when most of the material will be separated at the end of the belt's run. This is because restrictions on access to the belt may require stuck material to be removed from other directions when cleaning or otherwise maintaining the belt. With the diamond shaped cell pattern of figure 6a, it can be seen from figure 6b that although the peel resistance variation is low against the direction of travel, it is rather higher at 30 degrees to this. This may result in problems and hence delays in production when cleaning or maintaining the belt.

Figure 6c shows a slanted hexagon pattern, which has a peel resistance profile (figure 6d) that also shows "spikes" of higher peel resistance variation in certain directions. The next pattern (figure 6e) is a repeating pattern of irregular shapes, and this also shows "spikes" of higher peel resistance in certain directions as can be seen in figure 6f.

The last pattern (figure 6g) is non-repeating using irregular shapes and has a relatively uniform level of peel-resistance in all directions as shown by figure 6h. This is then a preferred arrangement for cleaning and maintenance as well as regular operation.

Irregular or fragmented non-geometrical shapes are preferred. Repeating and preferably non-repeating patterns of different shaped cells are also preferred. These patterns have been shown to exhibit good peel off properties, having relatively uniform peel off resistance in all directions. A fractal shaped cell and/or pattern of cells may also be used. Note that these types of patterns are also suitable for continuous belts. Whilst standard geometrical shapes such as diamonds and square cells have been applied to continuous belts, non-geometrical shapes are preferred as they improve the peeling characteristics of the belt.

However, short of expensive trial and error, there has not been a suitable way of determining whether particular patterns and cell shapes might be suitable for "wet" dough conveyance or similar applications.

Figure 7 shows a method of determining a peel-off resistance profile for any given pattern of cell shapes, whether regular or irregular. The candidate pattern is converted into a bitmap for example directly, by using a software paint package or by scanning in a line drawing. The bitmap will comprise bits equal to 1 corresponding to a cell wall, or zero otherwise. This is preferably converted into a two-dimensional array or matrix (for example using MathCAD) for mathematical processing; although other data structures could alternatively be used. A bitmap and corresponding array are shown respectively in figures 8 a and 8b.

Then for a number of angles θ the peel resistance is examined through the bitmap or belt surface pattern representation. This is done in this embodiment by determining the proportion or density of ridges in a scanning line which passes along a section of the bitmap at the respective angles θ. A line through the bitmap or pattern and corresponding to the angle will correspond to a peeling front of the sticky material moving across the pattern at that angle θ. At a plurality of points through these lines, the average density of dough in contact with the belt pattern is calculated. In other word the percentage of the peeling front where dough is in contact with the belt and in particular the walls or ridges of the belt is determined.

Referring to figure 8a in more detail, a section 20 of the belt pattern is shown, and comprises a pattern of ridges or walls 13 which cooperate to form the pattern of closed cells being tested. A partial series of scan lines 21 is shown for directions θ = 0 and θ = 45, and which are provided at intervals from position 0 to position X on the interval scales 22. The start of a 2 dimensional array is shown in figure 8b which corresponds to θ = 0. From the first scan line for example it can be seen that the left most point coincides with a wall and so is given the value 1, whereas the adjacent point is in the trough or depression of a cell and so is given a value of 0. The array or matrix is built up in this manner. It can be seen that the proportion of wall or ridge at each scan line is low, and that this will remain reasonably uniform throughout the scan intervals to position X.

By contrast, scan lines for θ = 45 illustrate that initially only a single wall point is included in the scan lines until interval 1, whereupon all the points of the scan line coincide with a wall resulting in a high proportion of wall.

For simplicity of implementation, the array corresponding to θ = 0 can be scanned in, and a suitable equation used to calculate the proportion or density parameter for each scan line, even for angles different from θ = 0.

Preferably the density at each point is calculated by:

M

Σ Wall mod(floor(j-tan(θ)+0.5)+i, N) ,j

Density . =

¹ M

where the index i ranges from 1 to N; j from 1 to M; mod() is the standard modulus function; and floor(x) returns the greatest integer < x.

The standard deviation σ for the calculated densities at each scan point for each angle θ can then be calculated to give a measure of how variable the peeling resistance is for each angle.

Once the calculations have been completed for all angles, the standard deviations σ can be plotted against the angles θ in a polar graph to indicate the pattern's performance; such as those shown in figures 6b, 6d, 6f, and 6h. Preferred patterns are those with generally low levels of standard deviation σ and which are free of high peaks in σ (which indicate that the pattern is not good for peeling at that angle).

An automated process for indicating whether a tested pattern is suitable can set thresholds of standard deviation σ and/or a measure of the uniformity of standard deviation σ, which if detected can lead to a positive indication for that pattern.

Other equations may alternatively be used, and a different measure of variability could also be used.

The accuracy of the results is improved with a wide scan line and a small interval between scan lines. However so long as the scan line covers at least a dozen cells and the interval between scan lines is significantly smaller than the cell size, then good results are obtained. Typically the bitmap array will be of size 750x750, but the only limit is the time needed to complete the calculation and larger sizes of arrays may be used.

An automatic design process can also be used to generate cell shapes and/or patterns of cells which are then tested by the above method. For example random selection of shapes and patterns can be achieved by assigning cell co-ordinates to "corner" points, and then varying incrementally the x-y locations of these co-ordinates.

The skilled person will recognise that the above-described apparatus and methods may be embodied as processor control code, for example on a carrier medium such as a disk, CD- or DVD-ROM, programmed memory such as read only memory (Firmware), or on a data carrier such as an optical or electrical signal carrier. For many applications embodiments of the invention will be implemented on a DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). Thus the code may comprise conventional programme code or microcode or, for example code for setting up or controlling an ASIC or FPGA. The code may also comprise code for dynamically configuring re-configurable apparatus such as re¬ programmable logic gate arrays. Similarly the code may comprise code for a hardware description language such as Verilog ™ or VHDL (Very high speed integrated circuit Hardware Description Language). As the skilled person will appreciate, the code may be distributed between a plurality of coupled components in communication with one another. Where appropriate, the embodiments may also be implemented using code running on a field-(re)programmable analogue array or similar device in order to configure analogue hardware.

The skilled person will also appreciate that the various embodiments and specific features described with respect to them could be freely combined with the other embodiments or their specifically described features in general accordance with the above teaching. The skilled person will also recognise that various alterations and modifications can be made to specific examples described without departing from the scope of the appended claims.

Claims

CLAIMS:

1. A conveyance belt module for a conveyance belt for conveying a sticky material, the belt modules comprising: a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges; a number of tabs extending the conveying surface to form a series of fingers at a linking edge of the module and arranged to receive corresponding tabs from an adjacent module in order to form a substantially gap free conveying surface.

2. A belt module according to claim 1 wherein the enclosed areas of the closed cells do not extend perpendicularly from the belt surface.

3. A belt module according to claim 1 or 2 wherein the closed cells extend over substantially all of the conveying surface of the belt module.

4. A belt module according to any one claim wherein the closed cells are arranged such that the peel resistance of the sticky material is minimised when peeling in opposition to the direction of travel of the conveying surface.

5. A belt module according to any one claim wherein the closed cells are arranged such that the peel resistance of the sticky material is substantially uniform when peeling in opposition to the direction of travel of the conveying surface.

6. A belt module according to any one preceding claim wherein the closed cells are pyramids in a plane parallel to the plane of the conveying surface, and wherein the pyramid cells are arranged such that a line drawn through two opposite corners of the pyramid is parallel to the direction of travel of the conveying surface.

7. A belt module according to any one preceding claim wherein the sticky material is a dough mixture.

8. A modular conveyance belt for conveying sticky material and comprising a number of belt modules according to any one preceding claim.

9. A conveyance belt for conveying a sticky material, the belt comprising: a series of ridges extending substantially perpendicular to a conveying surface of the belt and arranged to form a plurality of closed cell structures each having walls formed by the ridges which enclose an area of lesser perpendicular extension than the ridges; wherein the shape of adjacent cells is different.

10. A continuous or modular belt according to claim 9.

11. A method of determining a peeling performance profile of a sticky material being removed from a conveyance belt which has a plurality of closed cells formed by patterns of ridges on the conveying surface of the belt; the method comprising: determining a series of parameters corresponding to the peel resistances of the sticky material over a section of said belt; determining the variation of said parameter over said section.

12. A method according to claim 11 further comprising determining said variation over a number of sections corresponding to different directions across the belt.

13. A method according to claim 11 or 12 further comprising displaying said variation of said parameter in order to illustrate said performance profile.

14. A method according to any one of claims 11 to 13 wherein said parameter is the density of said ridges.

15. A method according to any one of claims 11 to 14 wherein said parameter determining comprises: mapping the closed cells onto a bitmap identifying said ridges; determining the proportion of ridges in a scan-line perpendicular to said section at a series of intervals along said section.

16. A method according to claim 15 comprising converting said bitmap into a 2- dimensional array and applying the following equation:

M

Σ Wall mod(floor(j-tan(θ)+0.5)+i, N) J

Density. =

M

17. A method according to claim 15 or 16 wherein said parameter variation determining comprises determining the standard deviation of said parameter.

18. A computer program product comprising computer code which when implemented in a computer is arranged to carry out a method according to any one of claims 11 to 17.

19. Apparatus for determining a peeling performance profile of a sticky material being removed from a conveyance belt which has a plurality of closed cells formed by patterns of ridges on the conveying surface of the belt; the apparatus comprising: means for determining a series of parameters corresponding to the peel resistances of the sticky material over a section of said belt; means for determining the variation of said parameter over said section.

20. Apparatus according to claim 19 further comprising means for determining said variation over a number of sections corresponding to different directions across the belt.

21. Apparatus according to claim 19 or 20 further comprising means for displaying said variation of said parameter in order to illustrate said performance profile.

22. Apparatus according to any one of claims 19 to 21 wherein said parameter is the density of said ridges.

23. Apparatus according to any one of claims 19 to 22 wherein said parameter determining means comprises: means for mapping the closed cells onto a bitmap identifying said ridges; means for determining the proportion of ridges in a scan-line perpendicular to said section at a series of intervals along said section.

24. Apparatus according to claim 23 comprising means for converting said bitmap into a 2-dimensional array and applying the following equation:

M

Density . =

¹ M

25. Apparatus according to claim 23 or 24 wherein said parameter variation determining means comprises means for determining the standard deviation of said parameter.

26. A method of generating a pattern of closed cell structures for a conveyance belt for conveying a sticky material, the closed cells formed by patterns of ridges on the conveying surface of the belt; the method comprising: generating a candidate pattern of said pattern of closed cell structures; testing said pattern according to a corresponding peeling performance profile method according to any one of claims 11 to 17.