Board testing apparatus

Abstract

A board testing apparatus and method and in particular a testing apparatus for testing a board made of a corrugated material, such as corrugated cardboard, for failure characteristics. The method comprises taking a corrugated board from a corrugator or converter, locating at least a part of the board into a testing machine, performing a non-destructive compression test on a sample region of the part of the board within the machine and providing a compression test characteristic reading of that region of the board, comparing that characteristic reading against a predefined acceptable compression test characteristic reading that design of corrugated board should have and concluding from the comparison as to whether the board, or that sample region of the board, meets a required compression stiffness parameter.

Claims

1. A testing machine adapted to carry out a method of non-destructively testing a structural characteristic of a corrugated board, the method comprising the steps of performing a non-destructive compression test on a sample region of a corrugated board of a known design, from said non-destructive compression test, providing a reading of said sample region's compression test characteristic, comparing that characteristic against a predefined acceptable characteristic that said known design of corrugated board should have, and concluding as to whether the board, or that region of the board, meets a required compression stiffness parameter, wherein the testing machine comprises: a) a support surface on which the region of the board can lay, b) a pressure plate with which a testing force can be applied to an opposing side of the board so as to apply a compression force across a thickness of the board towards the support surface, c) at least one sensor for sensing data, the data comprising a deflection by and a force from the board, and d) a database or look-up table for checking the sensed data against a predetermined force per deflection parameter for said known design of corrugated board.

2. The testing machine of claim 1, wherein the database or look-up table comprises test data for boards of various different design types so that the apparatus can look up an appropriate predefined acceptable characteristic readings for a range of different designs of said boards.

3. The testing machine of claim 2, wherein the database or look-up table comprises data comprising at least one of a deflection response and a force response and the database or look-up table further comprises data comprising a form of a design of the board itself, the data comprising at least one of flute profile type, material weight, and material type.

4. The testing machine of claim 3, wherein the material type comprises at least one of top web material, bottom web material, flute material, ply structure, and calliper.

5. The testing machine of claim 2, wherein the database or look-up table comprises data comprising at least one of first point-failure deflections, first-point failure forces, second-point failure deflections and second-point failure forces, wherein the predefined acceptable characteristic comprises at least one of the first point failure deflections and the first-point failure forces.

6. The testing machine of claim 5, wherein the database or look-up table further comprises third-point failure deflections and third-point failure forces.

7. The testing machine of claim 1, wherein the testing machine is adapted to carry out the non-destructive compression test using a degree of compression of the board amounting to less than 1 mm.

8. A pre-formed blank having structural characteristics and being ready for assembly into a packaging or box, said pre-formed blank comprising a top ply, a bottom ply and at least one corrugate therebetween, and additionally comprising a certification with respect to the structural characteristics thereof which have been authenticated during a production run for said pre-formed blank using the testing machine of claim 1.

9. A corrugated blank manufacturing line implementing the testing machine of claim 1, the line comprising a corrugator and a converter, the line further using calibrated roller pressures for the corrugator or the converter for a particular run of blanks or products made from said blanks, the roller pressures being calibrated by feedback from the testing machine, the line using the calibrated roller pressures to adjust at least one of a roller gap, a roller alignment, and a roller pressure of the corrugator or the converter.

Description

(1) These and other features of the present invention will now be described in further detail with reference to the accompanying drawings in which:

(2) FIG. 1 shows a box testing apparatus;

(3) FIG. 2 shows a dynamic stiffness testing apparatus;

(4) FIG. 3 shows a template cutter arrangement for cutting samples for use in the dynamic stiffness tester of FIG. 2;

(5) FIG. 4 shows a compression/deflection testing apparatus used for forming data for look-up tables for use in the present invention by testing undamaged samples 50.

(6) FIGS. 5 to 10 shown test data results or plots from tests carried out using the apparatus of FIG. 4;

(7) FIG. 11 shows a first arrangement for the present invention's board testing apparatus;

(8) FIG. 12 shows a detail of the support plate and pressure plate of that apparatus;

(9) FIGS. 13 and 14 show a further embodiment of a testing apparatus according to the present invention with a slot for receiving a board therein to be tested;

(10) FIGS. 15 to 19 show sample screen layouts for use on the screen of the test apparatus during a preferred testing process;

(11) FIGS. 20 to 34 show a preferred arrangement of testing apparatus and its mode of manufacture;

(12) FIG. 35 schematically illustrates a section through a corrugated sheet having a good corrugation in the core thereof, with the shape of the flutes clearly illustrated;

(13) FIG. 36 shows that same corrugated sheet but after a first point failure wherein the crowns of part of the waveform of the corrugations have collapsed. The height of the board is correspondingly reduced compared to FIG. 35;

(14) FIG. 37 shows that same corrugated sheet after a second point failure wherein the opposite crowns, or all crowns, have now failed. The height of the board is again correspondingly reduced, now compared to FIG. 36; and

(15) FIG. 38 shows a complete failure of the corrugation/flutes, whereby both the crowns and the walls between the crowns have failed. This sheet is thus such that the corrugated board has fully collapsed, whereafter the corrugations will provide minimal compression resistance. The height of the board is thus even further reduced, now compared to FIG. 37.

(16) Referring first of all to FIG. 1, a box compression test (BCT) apparatus is illustrated. As previously discussed, in this apparatus, a box 10 is located between an upper plate 12 and a lower plate 14 and is compressed to the point of failure. Typically the failure is observable as the corners of the box 10, or at the edges running between the upper plate 12 and the lower plate 14by sight of a propagating crease. This failure also provides a clear drop in the compression support force provided by the box 10, which can readily be seen in a deflection versus force graph, a plot of which may be displayed on an adjacent computer screen 22 of a computer 20. This test is a well-recognised test in the art for providing an absolute compression strength of a box. Unfortunately, however, it is somewhat inaccurate in terms of identifying part failed boards, since the failure identified by the test is determined by the structural failure of the box, rather than the structural failure of the material of the box. It is also relatively slow to perform due to the need to assemble the box prior to undertaking the test and due to the larger deflections needed to achieve the detection of the failure, and thus to provide a box strength reading (be that a value or a pass/fail indicatione.g. if there is a target strength).

(17) It is also to be observed that since the whole box is tested, rather than just an area of the box, imperfections in the squareness of the corners, or of the true-ness of the folds, can also lead to significant initial deflections as the box settles into the machine's compression cycle, whereby the test struggles to provide detailed strength readings, as opposed to failure values. This is a common problem with tests carried out on complete blanks, or boxes made therefrom, but is less of an issue in tests carried out on samples extracted from the blanks.

(18) Referring next to FIG. 2, such a more reliable test, carried out on a sample extracted from a blank, is illustrated. In this test, a sample is taken from a blank and it is tested by a dynamic stiffness tester or DST apparatus. As also already disclosed above, this apparatus provides a dynamic stiffness reading for the material of the blank, rather than a strength reading for the blank as a whole, this time through a torque loading of that sample. It is considered to be more accurate and repeatable in terms of the provision of a reading as to the quality of the board. These DST tests, however, tend still to be a fairly slow testing process due to the need to cut out the samples from the blank and then to load the sample firstly between two clampsone at each end of the sampleand only then to perform the DST test.

(19) Although perhaps quicker than the BCT, and more portable since the DST apparatus is significantly smaller than the BCT apparatus, the test procedure, including preparing the sample, may still take minutes, and when carried out on 20 to 30 product runs per day, as would occur in a cardboard packaging production line (each run producing a different product, be that simply a different print run or a different board type, or a different cut-profile), perhaps with multiple tests being required on any given product in order to fine tune the press weights of the conversion apparatus, or other rollers, cutters and folders or the like within the production line, even this faster test is still considered to be too slow to be commercially viable on all product runs. After all, if each test takes two minutes, even a single test per product results in an additional downtime of one hour (two minutes30 product run changes), and that time will be in addition to the essential downtime created by the roller/material switch-overs between product runs. Nevertheless, the test results are repeatable and reliable and are thus recognised as a good indication of board quality. As such a number of production lines now utilise such tests as a corrugation quality test procedure.

(20) A further problem has been identified, however, with the roll-out of DST tests: due to the need to cut out the samples from the board exiting the production line, it being those samples that are necessarily loaded into the testing apparatus (due to the mode of testingproviding a twist in the sample and then analysing the elastic recovery), there is a susceptibility to variation in the test results due to faults put into the samples by the process of cutting out the samples, or by the process of loading the samples into the clamps 26, 28. For example, too high a clamp force can be provided, and since boards can have different thicknesses and strengths, the regulation or standardisation of that clamp force is not straightforward. Alternatively, if the blade used to cut out the sample is less sharp in subsequent samples, the corrugations can be variably damaged.

(21) The load applied to the guide form or sample template during cutting out of the sample, or the speed of the cutting (or the number of passes of the blade required to complete the cut) can also all introduce variables.

(22) A new test procedure would thus be beneficial to allow both accuracy and speed in determining whether the corrugate meets the standard strength requirements for the type of board that it is.

(23) Eliminating the use of a blade in the production line (i.e. for cutting out the samples for testing) would also be desirable since that can eliminate the health and safety concerns surrounding the use of such blades in the workplace.

(24) One other type of test has also been carried out in practice since it is quick, and it is simply a test or determination of the calliper of a board, i.e. the thickness of the board. That measured thickness can be compared against the standard for that form of board and if the board is too thin (orless likelytoo thick), then the board would not meet the requirements for that board type and would thus be able to be rejected. However, it is recognised that a calliper test is inadequate for determining whether a board is only partially damaged since corrugations tend to have a degree of resilience, whereby they can spring back to a starting thickness if only compressed by a certain amount (albeit enough of a first deflection to cause some damage to the structure of the flutes within the board). A calliper test thus can provide an accurate determination as to whether the flutes are correctly supporting the height or spacing between the faces of the board, but a calliper test cannot determine whether the flutes have undertaken a prior collapse and elastic recovery. That latter deficiency is a problem since if the flutes have undertaken a first preliminary collapse (aka a first failure), the corrugate will not have the same overall stiffness and strength characteristics as if the flutes had not undertaken such an initial collapse, rather like fibreglass crash helmetsthey are not as strong after a first impact.

(25) This imparted weakness in the flutes following a first partial compression can be seen from the deflection/load traces in the graph of FIG. 10, where repeat tests were carried out on various samples, and each to different degrees of failure, so as to show the different trace characteristics in such circumstances.

(26) The tests carried out are numbered from 1 to 6.

(27) The first test was carried out simply to illustrate the existence of first, second and third point failures. For the general form of these failures, see FIGS. 35 to 38, which represent the mode of each of these three failures by providing a generalised illustration of the flute form in section at each failure point.

(28) The three point failures are represented by the three peaks 58, 60, 62 in the trace, with the first peak 58 corresponding to a first flute failure, as shown in FIG. 36. This is where the crown of a first of two opposing flutes within the waveform of flutes fails (or buckles). The second peak 60 then indicates a second flute failure, corresponding to FIG. 37 where the crowns of both the top and bottom waveforms of the flute collapse, fail or buckle. The third peak 62 then indicates a final collapse of the board. In this failure, the walls between the crowns also start to collapse, fail or buckle. See FIG. 38.

(29) The second test was then carried out on a new sample with no damage. Its trace is shown to be displaced along the X axis relative to the first trace, but this just represents a different start point therealongthe forces measured during the loading characteristics are otherwise clearly similar to the first trace.

(30) As can be seen, in this second test, the loading was commenced, but it was also ceased prior to the degree of compression causing a loading force corresponding to that first failure point 58, i.e. the loading peaked at about 500 N, whereas the first point failure occurred in the first trace at a load of about 600 N. As such, a degree of flexure was undertaken by the flutes, but the flute did not fail.

(31) Upon releasing the compression, the board elastically reassumed its starting thickness.

(32) That same sample was then tested again in a third test (a second test for that second sample) and the trace can clearly be seen to be repeating the same curve, albeit shifted again along the x axis (by about 0.1 mm) in the graph due to it again having a different start point (e.g. since the elastic recovery was not perfect, whereby there may have been a slightly smaller calliperperhaps the 0.1 mm mentioned above).

(33) A fourth test was then carried out on another new sample (first test for this third sample) and that sample was tested through the first failure point but was ceased from further deflection just prior to the second failure pointat a deflection point above and beyond the load point of the first failure point 58, but less than the second failure point 60. This was done so as to allow a subsequent test to be carried out on that same third sample, but this time with that sample now being a part failed sample.

(34) The fifth test is the second test on that third sample, i.e. a test on a part failed sample, and as can be seen the first peak failure 58 simply does not occur, and the trace initially follows a much lower path towards the second point failure. Then the trace simply flows up towards the second point failure 60 (although the compression of this third sample was again not taken to that second point failure 60.

(35) The sixth test was then again carried out on that third sample, but this time it was instead taken to a final failure. The trace is again slightly shifted due to a different start point, but it initially generally follows the trace of the fifth test.

(36) It can also be seen in this sixth test trace that the loading required for the second point failure 60 is roughly the same as in the first test (around 900 N). Likewise the load for its final failure was also similar to the first test (around 1700 N).

(37) The end of the trace going upwards simply indicates the full compression of the board whereupon the loading increases as the plates of the test apparatus push against each other through the compressed corrugated sample.

(38) From the above it is clear, therefore, that observance of the loading characteristics in response to initial deflections can give an indication as to whether the board has already undergone a first point failure. Such a failure is the type of failure that might be inflicted upon a corrugated board during the corrugation process or during the conversion process, e.g. if the roller gaps or the roller pressures are set incorrectly, but yet would not be detectable by a calliper test. The present invention therefore tries to detect such a failure so as to allow a supplied board to be certified as being in compliance with the requirements of the board type being supplied.

(39) Due to the non-existence of the first failure point in a damaged board resultant of a first flute failure, a comparison of the trace or force versus deflection curve allows such a determination as to whether or not a board that has undertaken processing in a roller based converter or corrugator has been damaged by that process or not. If it exhibits the initial strength characteristics of a non-damaged board, it will follow a path towards a first failure point, but if it has been damaged by that processing so as to have already undertaken the damage to the flutes, it would instead exhibit a lower loading characteristic upfront before reverting towards the second point failure point.

(40) It is therefore possible through comparison of test data on a live sample, and comparing it against the expected test data for a pre-tested sample of a non-damaged form, to determine in a non-destructive test whether a sample is damaged in that way, or not.

(41) Referring next to FIG. 4, a test apparatus that can be used to produce sample data for a look up table on undamaged products is shown. In this example, disks of typically an 80 mm diameter are cut from boards known to have not been damaged, and test data can be obtained therefrom whereby the data behind the curve corresponding to that of the first test in FIG. 10 can be obtained for all different forms of board that are to be produced by the production line. This can include test data for boards made from various different top sheets, different bottom sheets, different corrugations (shapes, frequencies and amplitudes), plus also various different corrugation/board thicknesses, and ply numbers. This data can then be provided for a look-up table for comparing against live data on actual product of the production line, e.g. for a live product.

(42) Referring next to FIG. 5, six traces of separate tests through to failure are shown, with four of them being on undamaged stock and two of them being on damaged stock, and thus following a different path towards the second failure pointthe first point failure does not occur. As can be seen, the undamaged stock have traces that follow a path with three clear inflections, each representing one of the three failure points previously described. The other two traces have only two clear inflections.

(43) FIG. 6 then shows similar tests on a different type of boardin which the corrugate is made of a more stiff material. In this test, again four of the traces follow substantially the same form whereas the other two clearly do not exhibit the first failure point inflection. Damage again can thus be identified simply from an analysis of the early part of the curves (or the early response to deflective loading).

(44) FIG. 7 then shows six further traces, again where four boards exhibit the three failure points whereas two only exhibit two. In these samples, a thicker flute material is used and a greater variation in the final failure point is exhibited. Nevertheless, the first failure point is still adequately repeatable to allow a determination to be made since there is a distinct difference in the trace of the two damaged boards compared to the non-damaged boards. Thus again a study of the early load response to deflections can indicate whether a board has been damaged.

(45) FIGS. 8 and 9 show yet further traces for boards made from the stiffer flute materials and yet again the existence of the first failure point in a board that passes the test is readily apparent, when compared to the two boards that are damaged, whereby a pass or fail of boards can be achieved based upon the initial response to loading.

(46) It is clear, therefore, that by looking for the compression resistance (herein measured in Newtons) of a live sample to a given deflection and comparing that to the expected response to such deflections, and perhaps looking at that at a point between, for example, 50 and 90% of the expected first failure point, the quality of the fluting can be determined. Likewise, the deflection resulting from a fixed loading can be measured and compared with expected deflections for that loading, again at say between 50 and 90%, or more preferably about 85%, of the first point failure, can provide an indication of flute status. If the board passes the test, then the fluting is in a correct or acceptable condition whereas if it fails the fluting has been adversely damaged, for example by the processing of the corrugate.

(47) The present invention initially relates to that test procedure since it allows a quick test to be carried out since it is not necessary fully to collapse the corrugate to undertake the test and secure a reliable reading. Preferably the test is carried out directly on the board as it exits the production line, either before or after the conversion thereof, i.e. without cutting samples from that board. The test apparatus thus has a gap or slot for receiving an edge of a board.

(48) In view of the faster test, it is also possible to have the test carried out beside the production line whereby an operator can perform tests and fine tune the roller pressures so as to avoid damage to the board during production of the board or conversion of the board into the respective blank's further customer. This can even be done multiple times a minute since only a very small deflection is needed to get a test resulttypically less than 1 mm or even less than 0.5 mm.

(49) The inventors have also recognised that a single test on a width of corrugate passing through a corrugation machine or a converter is not always going to be adequate or accurate for a board as a whole since there can be variations in the wear or set up of the rollers within the corrugator or converter. For example, one edge of the board may be more compressed than the other, or the middle may be compressed more than the edges. This can occur, for example, if the roller has worn, e.g. so as to be tapered along its length, or even if it is just misaligned slightly. The present invention therefore also provides a method in which multiple tests are carried out across the width of a single board. With the prior art methods, since samples had to be cut out from the board, this would then involve cutting multiple samples from the width of a board, thus further lengthening the testing process. The present invention, however, achieves the full multiple test process without cutting such samples from the board, which saves time since cutting out samples slows down the testing process perhaps to an unacceptable level. According to the present invention, therefore, it is desired that the board be tested intact, rather than samples being cut therefrom for testing. It is also preferred that the test preparation and performance cycle be shorter than 20 seconds.

(50) In a preferred arrangement, the intact board or blank is tested in multiple locations thereon. For example, for a blank for a box with four sides, the test may be carried out on all four panels for forming the sides of the box. If there are more sides, then more tests may be appropriate, although testing every side is not essential. Likewise if there are flaps or other significant panels, they too might be tested. Again, however, that is not essential.

(51) It is preferred that the test preparation and performance cycle for each of these tests be shorter than 20 seconds. Collectively they may take longer than 20 seconds.

(52) Preferably the present invention involves testing a board in more than one location and more preferably in four or more locations.

(53) The board may be a finished blank or it may be a cut board or width of board from the corrugator, i.e. prior to insertion through the converter, or a part formed blank or board sitting on the feed tray of the convertor unit. Tests on the latter two can provide a reference for the post converted, or finished, blank. Then, if the conversion machine provides damage to the blank, this can be later identifiedby a subsequent test on that earlier blank after the conversion process. The conversion machine can then be adapted or its pressures can be lowered, to correct or remove the set-up error therein. However, if the first test shows instead that the corrugation machine is causing the damage, then the corrugation machine can instead be adjusted.

(54) Since the machines within the production line tend to have button controls for adjustment of roller pressures and the like, by having the testing apparatus beside the control apparatus for the corrugator or the converter, rapid testing of the boards or blanks combined with the quick and easy adjustment of the roller pressures can allow the blanks coming out of the converter apparatus rapidly to be fine-tuned so as to provide desired results.

(55) It has been found that with the present invention, more than three and maybe four or more tests can be carried out, with adjustments to the machinery where needed, per minute, with the test itself perhaps taking just 3-6 seconds.

(56) It is preferred that the tests are carried out in a controlled environment. This would include the testing that is carried out for populating the look-up tables and also the testing carried out at the production line during the manufacturing process. Preferred environmental temperatures in most cardboard packaging industries are 23 C. and 50% relative humidity, +/1 degrees and +/2%. The controlled environment provides a foreseeable or repeatable characteristic to the board, which can be especially important with wood or cellulose fibre based corrugates.

(57) As already indicated, by locating the testing apparatus adjacent the production line, product can easily be taken off the production line while the production line has been halted. That product can then be tested and then the production line adjusted if necessary. Then the operations of the production line can be reinstated into production mode to throw out the next product for testing (e.g. if an adjustment was previously made) to check the modified product for conformity with the required standard.

(58) Since the test is carried out on the product, rather than a sample cut therefrom, or even on a reshaped product (e.g. an assembled box therefrom), and since the test is only looking at the initial response to loading, the test procedure is fast enough to allow multiple tests and production line adjustments, and resumptions of production, to be conducted in a minute, or in the time previously taken to do a box crush test or even a dynamic stiffness test.

(59) The quicker test therefore reduces down-time between production runs, thus increasing productivity. It also allows production line damage to be reduced, thus allowing greater efficiency in the use of materialschosen materials can achieve more consistent strength characteristics in the resulting corrugated sheets/products, and since the method can identify damage caused by the production line, and thus then eliminate it in the remaining product production for that production run, a smaller safety margin on strength can be used by the manufacture for the customer, thus allowing lighter packaging to be provided while still consistently providing the required strength performance demanded by the customer.

(60) These weight reductions can also reduce environmental damage since the packaging will use less raw materials, and can also reduce transport costs since there will be less packaging to transport/recycle.

(61) Referring next to FIG. 11, a first embodiment of testing apparatus of the present invention is shown. It comprises a support surface 46 onto which a board to be tested can be located, a pressure plate 48 for imparting the test pressure onto the board thereunder, and a frame 54 for supporting the pressure plate 48. In this embodiment the frame additionally supports the pressure plate's drive rod 64, the force sensing displacement mechanism 56 and the load sensors or senders 52 for sending data to a computer 66 via a cable 68 (in this case a USB cable to a separate PC/laptop).

(62) The apparatus also comprises a power unit 70 provided to supply the power to the force sensing displacement mechanism 56 and the load sensors 52. This embodiment also has a second power unitprovided since there are components that operate at different voltages, or since there wants to be a separation in the power supply between the drive motor and the sensors to avoid interference. However, a single power unit might instead be provided if preferred to reduce costs.

(63) The support plate 46 in this embodiment is formed of a single component with its legs 72for standing the test apparatus on a table. It is also possible for it to be an integrated design with the frame 54.

(64) The pressure plate is significantly smaller than the support plate in this embodiment. However, different arrangements are also possible, as illustrated in FIG. 1 or 4 for example (where they are the same size). Making it smaller than 10% of the size of the support plate is preferred, however. Having a small pressure plate allows the drive unit for the pressure plate to be small, yet still capable of providing an adequate pressure onto the board in the test apparatus. Having a large support plate, on the other hand, is preferred since it can then still offer a stable support surface for the board being testedthe board will have a reduced tendency to rock on the support platea potentially important benefit bearing in mind that the board may be being held within the test apparatus by an operator.

(65) The power supply 70 may be connected to mains power through further cables 74 and may thus comprise a voltage converter.

(66) In this embodiment, the force sensing displacement mechanism 56 is in the form of a moving coil actuator, or a voice coil, and it is preferred that it is able to provide displacement measurements up to an accuracy of at least 50 micrometres, or more preferably 10 micrometres, or better still 5 micrometres or 1 micrometre. Accuracies up to between 1 and 0.1 micrometres may in some instances be beneficial too, although generally this would not be essential. About 5 micrometres is the accuracy of the preferred device.

(67) For small pressure plates as discussed above, it is preferred that the drive unit be able to apply loads of up to 100 N, or 150 N or even 200 N. Larger forces become non-essential due to the small pressure plate. A preferred device provides loads of up to 185 N. This is typically adequate for testing apparatuses having a pressure plate 48 in the form of a 25 or 20 mm diameter disk. The pressure plate may of course be larger or smaller than that. Likewise the force capability of the drive unit may be larger or smaller than 185 Newtons.

(68) Since the fluting is not needed to fail completely during the test, and since the load area is smaller, smaller loads are required than in box compression tests, or in the lab equipment used to test the 80 mm discs of FIG. 4.

(69) One style of power unit that is suitable for the present invention's testing apparatus is a moving coil actuator. Manufacturers of such equipment include SMAC. Such devices can be linear and linear/rotary actuators, and two possible model numbers are the LAL 300 and the LAL 500, both by SMAC. Others include the LAL 95-015-85 unit by SMAC. Preferably they have a high speed single axis controller. A suitable controller may be the LAC-1 controller by SMAC.

(70) It is preferred that the arrangement will provide a displacement measurement and a load reading for that displacement with a stroke length of up to 15 mm, 25 mm or 50 mm, whereby it is perfectly adequate for testing corrugated sheetssuch sheets are rarely thicker than 10 mm.

(71) Referring next to FIGS. 13 and 14, a modified version of the testing apparatus is shown. In this modified version, the computer is incorporated into the housing itself and thus there is a screen on the front of the testing apparatus. This screen is a touch screen to allow user interaction for controlling the test procedure.

(72) As also shown in FIG. 14, a slot is provided into which the board can be slipped for the purpose of testing. That slot 76 is preferably at least 10 mm wide so as to accommodate board thicknesses commonly found in the corrugated business. Wider thicknesses for the slot may also be used if appropriate for larger boards to be sampled. The slot is shown to be of a fixed width, although it might be adjustable if desired, e.g. for securing a board within the slot for the duration of a test. Note though that such a securement is preferred to be absent since it might become a cause for damage to the board.

(73) The slot arrangement is beneficial since it allows an edge of a board to be presented very rapidly into the testing apparatus. A slot can also provide a safety guard mechanism since a slot is restrictive in terms of the access it provides, without hindering the test apparatus' ability to receive a corrugated sheet quickly. For example, the slot will resist the insertion of the operator's fingers that hold the sheet since the fingers are unlikely to additionally fit within the slot, but is wide enough to readily receive the board's edge.

(74) In use, the touchscreen 78 may have numerous software icons or buttons on the screen, which buttons or icons 80 may vary from mode to mode of the testing apparatus. In FIG. 13, an initial mode is shown in which there are various option buttons. For example, the type of test to be carried out can be selected or the type of board to be tested can be selected.

(75) It is preferred that the machine be connected to the production line's network so that it can be automatically provided with details of the current production run, or so that it can upload them from a database, e.g. from a product order number. However, the details might instead be user selectable on the screen, e.g. via drop-menus or an input device such as a keyboard (virtual on screen, or a separate hardware one).

(76) FIGS. 15 to 19 show further screen options, e.g. for later test steps.

(77) The screen of FIG. 15 allows the materials of the board to be indicated or set. The manufacturing order number (MFO) is indicated at the top of a first table 82, and in this table there is also indicated the designated details of the type of board expected for that order. In this example there is a board with a type-C flute, made from a FHY type of material having a weight of 130 grams per square metre (GSM), and with liners top and bottom having a KBR or Kraft type and a weight of 135 grams per square metre.

(78) In a second table to the right of the first table, other options can be selected if desired from the presented drop-down list, such as the flute type in this instance. For this purpose, the entry Flute Type is selected on the left hand table, as indicated by the arrow thereagainst. Being a touch screen, this may be by pressing the relevant box of the table 82 with a finger. Thus a different flute type can be selected from the drop down list on the right if appropriate (e.g. if the production run is modified from the default for any reason).

(79) Once the type of board is indicated on the screen and it conforms with the board to be tested, the user can press the confirm button to move to the next stage.

(80) In this embodiment, a reference test is first to be undertaken and in this instance that is in the form of a feed board test. It is preferred that this occurs for each production run, or whenever the corrugator is adjusted (rather than just the conversion machine). For this purpose, a board from the output of the corrugator, or more preferably from the feed end of the conversion machine, i.e. prior to a pinch point by a feed roller of the conversion machine, is removed and inserted into the test machine so that the test can be run thereon. This is to ensure that the corrugator is producing correct board and that it does not need to have its roller pressures updated or changed. This reference test is also beneficially used as part of the overall compression testafter the conversion of the board, as will be described in further detail below in relation to a preferred embodiment, since it provides a calliper for the board prior to feeding into the conversion machine.

(81) In the process of testing, the deflection and force readings are taken and are compared against data from a look-up table, with the normal readings for that board type having been determined previously under laboratory conditions. Assuming that the feed board meets those standards, the boards from the convertor, i.e. converted board or product, can then be tested at the next stage.

(82) FIG. 17 shows a preferred next stage screen, which is ready for receiving the blank. That blank might be printed or plain (or pre-printed) and a button can be pressed on the screen to select this. This is a preferred option since the type of printing on the blank can change the characteristics of the board as a whole due to it potentially being a further layer on the board, e.g. in the event of use of pre-printed cover paper, or it can mean that the board has undertaken a further compression cycle in the event of an inline printing process involving the use of print roller. Then the tests can be gotten underway.

(83) As shown in FIG. 18, a first area of the board has been tested and it has passed. In that test, the board was inserted in the slot and the run-test button was pressed. The pressure plate then pressed down on the board to squeeze it against the support plate and the apparatus simultaneously took deflection/loading readings, perhaps at a 85% deflection point relative to the known first point failure point for that board type (as predetermined under lab conditions). 50% to 90% would also be possible. Before the loading, however, a soft landing calliper was taken to determine the pre-compression thickness of the board. This can be compared with the similar calliper taken for the board when it was a feed board, i.e. prior to conversion.

(84) Then in FIG. 19, second and third sections have been tested. The second section has passed but the third section has failed. For the purpose of achieving such a result, the tested board had been deliberately damaged (e.g. compressed with fingers) in the area of the third test so as to create the fail result. In practice, a fail would generally only occur if the production machinery caused the damage.

(85) To improve the test process, rather than having a single fail cause the board as a whole to fail, a rule can optionally be applied, as here in this example, to help the test process to ignore localised failures. For that purpose, a single fail is generally not enough to fail the product.

(86) As can be seen in FIG. 19, there is also, below the picture area 86 to the left, a traffic light system for indicating whether the board or blank as a whole passes or fails. This, although optional, beneficially works together with the multiple-test test procedure. In this case, despite the third section's fail, the product is still overall a pass (although there is a fourth test still to do), since the top line 88 of the traffic light systemwhich records the overall average score required in order to create a faila figure that can be absolute for a given board type, or set individually for an order for meeting customer demands (some want greater strengths for a given board, whereas others are not too worried about the board's strength)is still not reached by the running-average score 90. Indeed, that running average score 90 is actually still overlapping the green traffic light area 92 since the first two tests had good results, and the third was a borderline fail.

(87) If the average score following the fourth test was then to enter the amber warning region 94 (or even the red region 96 in this example since the top line (or the pass bar 88) defines the point at which failure is to occur), then an overall warning or fail would occur, as appropriate.

(88) The present invention therefore not only does tests but can also provide average score tests. This is beneficial since it allows a localised fault not to cause the blank as a whole to fail.

(89) Further, a customer or manufacturer can specify the conditions for a fail (average fail/singular fail, amber fail, red fail), whereupon there is added flexibility. This then allows a manufacturer to avoid failing a board that is otherwise going to be perfectly acceptable to a customer. This can then speed up production runs even further, or even potentially prevent a large volume of paper to be wasted compared to the situation where the provisional materials specification cannot meet the required customer specification, which clearly offers an environmental benefit.

(90) Referring finally to FIGS. 20 to 34, a preferred assembly for the flute integrity tester of the present invention is provided. As can be seen in FIG. 20, the flute integrity tester 100 comprises an internal mechanism 102 and a hinged cover 104 with a touchscreen 78 at a front thereof. Underneath the edges of the hinged cover 94 (when it is in its closed position, as generally seen in FIG. 13) the slot 76 can be found. In this figure, the pressure plate 48 has already descended against the support plate 46 by the force sensing displacement mechanism 56 having extended its drive rod 64, e.g. to obtain a zero datum.

(91) The cables inside the apparatus are not shown in these drawings for ease of reference, but see FIG. 11 as an example of the type of cables that might be provided.

(92) A force sensing displacement mechanism 56 operates a cylinder for moving the rod up and down and in this embodiment this is via a moving coil actuator or voice coil system, although alternative modes of displacement are also possible such as mechanical, pneumatic, hydraulic, screw drive or belt drive and other known modes of displacement for rods.

(93) The drive mechanism is connected in this embodiment to a controller for the cylinder, that controller 106 being connected to a first power supply 70 as seen in FIG. 34.

(94) In this embodiment, a second power supply 108 is provided on the opposite side of the frame to the first power supply 70 and it operates under a different voltage for controlling the sensor rather than the drive rod. Other voltage requirements might be needed for other controllers or sensors. A single power unit is also a possibility (or multiple voltage controllers can be provided instead).

(95) Referring then to FIGS. 21 to 34, the steps involved in assembling the product are shown.

(96) The method starts off with the base plate or support plate 46 with a back frame assembly 110 which may all be one piece, or multiple pieces attached together. FIG. 21 shows the side elevation whereas FIG. 22 shows the plan view from above. As seen it is formed of a single component, e.g. a single moulding.

(97) A support frame 54 is then bolted onto the back frame assembly 110 and as can be seen in FIG. 24, the frame 54 of this embodiment has a generally U shaped configuration for receiving the force sensing displacement mechanism 56, or an actuator therefor, therein.

(98) On the top thereof, the load sensors 52 or controller 106 are mounted. See FIGS. 25 to 28.

(99) The illustrated and discussed positions of the various components are the preferred positions for this embodiment. Other component positions and arrangements are also, of course, possible instead.

(100) Thereafter, guard plates 114 are fitted to the front and back of the unit and then a larger finger guard 116 is attached to the bases thereof to create a barrier for preventing finger access into the testing equipment. The form of the slot is thus defined. The form of the slot might instead be formed, however, by the housing of the apparatus, or the bottom edge of the cover 104.

(101) The power supply units can then be fitted, for example as shown in FIGS. 31 and 32. Herein they are attached to the sides of the frame before the cover is then attached over the top of it all.

(102) This assembly provides a one-box testing apparatus with integrated screen and touchscreen control, and with the slot being provided therein for receiving the board directly, and without any pre-clamping thereof within the test apparatus.

(103) The present invention therefore provides a novel testing device and a highly accurate and fast method for testing blanks and boards at the production line without creating lengthy downtimes for the production line.

(104) Since the board types being manufactured are pre-tested to determine the standard responses to compressive loading, and the live tests only need to look at a look-up table to determine whether the actual boards in use meet the standard, the test results are quick and easy to recognise as being either a pass or a fail.

(105) There can be times when a bespoke or untested board is specified, and thus if the board being manufactured happens not to have been pre-tested, i.e. standards are not to be found in the look-up tables, then the system can flag up the deficiency and test data can be uploaded for future use thus adding to the flexibility of the database.

(106) Since the database of the look-up table can be constant from one production line to the next, they can be centrally controlled and networked whereby multiple machines can rely upon them, e.g. at single or multiple production line locations or in different countries. Further, when a new test result/standard is obtained and added from a lab-test, all locations can receive or access that new test result/standard.

(107) Further, since a feed board can be tested before the final conversion, an operator does not need to rely just on a visual inspection of the feed board.

(108) Further, the test results thereon can provide an indication as to whether a failing board met the standard prior to conversion or only after conversion. This reduces the amount of time needed to identify where the fault occurred.

(109) In addition to the new test, calliper thicknesses are preferably also determined by the present invention since they can also be compared against standards, or used in determining the actual compression/deflection from the default state. The basic calliper value, however, allows the calliper test to be carried out and that is important since if a significant change of calliper is noted, this can also be an indication of significant damagesuch as might cause the new compression test to give a false positive, whereby there is a double check.

(110) The present invention additionally, due to the shape of the testing unit (which has a relatively wide but narrow slot, and a relatively small housing thereabove), allows the testing not only of flat blanks but also of assembled boxesif of an adequate size, and if having accessible edges for fitting into the slot of the testing apparatus. For example, the testing apparatus preferably has a width of about 20 cm and a height above the slot of about 20 cm. Therefore a box having a top opening with a width of at least 20 cm and a length of at least 20 cm, and a hole height sufficient to allow the board to pass between the pressure plate and the support plate, will be testable along all four sides thereof.

(111) Preferably the dimensions (height and width) are no more than 40 cm.

(112) The present invention's illustrated test is described with reference to an average of the readings for four tested parts of a board. However, it might be preferred that a total score be used.

(113) With the present invention, tests can be done in seconds, and generally faster than 10 seconds, whereby it is possible to recalibrate print or roller pressures in a corrugator or convertor also in secondsrather than in minutes, since pressing a button can adjust the print or roller pressures and since the test results come back very quickly on the screen.

(114) At present, the system is designed to be run in a separate machine to the inline corrugator and conversion devices. However, it is anticipated that it could be incorporated inline on the production line, such as through the provision of multiple test units across the widths of the corrugation or conversion machine, typically each defining a gap rather than a slot. However, the fact that someone needs to be present at the side of the machine anyway to check visual print quality and visual flute quality, having him do the test as well is not particularly going to change the product processing speed. Indeed, it may even accelerate it compared to the current procedures using the BCT or DST tests.

(115) The present invention has therefore been described above purely by way of example. Modifications in detail may be made to the invention within the scope of the claims appended hereto.