Method for providing compensation sheets for a press station and setting up a corrugating machine

Abstract

A method is provided for providing compensation sheets (34) for individual specific press station units (16) of a corrugating machine (10), particularly a die-cutting and / or creasing machine. The method includes determining non-uniformities in the upper platen (24) relative to the lower platen (26) of the press station (16) during the pressing process, defining at least one compensation sheet (34) of varying thickness to compensate for the non-uniformities, and manufacturing the sheet (34). The shape of the sheet is independent of the converting operation being performed by the machine. Furthermore, the method provides multiple compensation sheets (34, 34'), each optimized for a given operating pressure.

Description

[Technical Field]

[0001] The present invention relates to a method for providing compensation sheets for a corrugating machine, in particular a press station of a die-cutting and / or creasing machine, and to a method for setting up a corrugating machine. [Background technology]

[0002] In corrugating machines, particularly die-cutting and creasing machines, corrugated boards placed at a feed station are gripped and transported through a press station, a waste discharge station and a blanking station.

[0003] The press station can cut the cardboard and create creases. A crease is a compressed section of the cardboard that is configured to be folded to create a box. To create the cut or crease, the press station has a lower platen and an upper platen disposed above the lower platen, the platens being movable relative to one another. Each platen may be fitted with a knife and / or a creasing rule and a tooling plate that holds a creasing member corresponding to the knife and / or creasing rule.

[0004] To achieve a precise cut, the pressure applied to the cardboard must be uniform, and the distance between the plate and the knife must be very precise, on the order of a few tens of micrometers.

[0005] The pressure applied varies depending on the material of the cardboard and the shape to be cut.

[0006] When cutting or creasing the cardboard, high pressure is exerted on the plates of the press station, which can cause the plates to deform slightly, adversely affecting the quality of the cut.

[0007] Currently, when setting up a corrugating machine, a test cut is made with the desired knife layout. The test cut is inspected by an operator, and based on the results of the test cut, the operator manually adds patches to areas where the test cut was not performed properly, creating a patch sheet. The patches locally increase the thickness of the setup, thereby compensating for plate deformation. However, this procedure is time-consuming, wasteful, and requires experienced operators.

[0008] German Patent Application Publication No. 3907826 discloses a method for creating and testing patch sheets outside of a corrugating machine using a separate impression machine to reduce downtime. This separate machine can apply variable pressure to different positions on the sheet, allowing the operator to determine the pressure to apply to each cutting knife to achieve a clean cut and thereby compensate for knife inaccuracies. To convert pressure to patch thickness, the method measures the deformation of the upper and lower platens when different pressures are applied in a uniform manner across the platen surfaces. Given the required pressure for each cutting knife, the method calculates the patch thickness to be applied on each knife by combining this thickness with values ​​from a prior calibration of the separate impression machine. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] DE 3907826 A1 Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to provide an optimized solution for compensating in a simple way the unevenness of the platens of the press station of a corrugating machine. [Means for solving the problem]

[0011] This object is achieved by a method for providing a compensation sheet for a press station of a corrugating machine, particularly a die-cutting and / or creasing machine. One of the method steps determines the non-uniformity of an upper platen relative to a lower platen of the press station during the pressing process. The non-uniformity can be determined for each platen individually and then combined, or it can be determined as a relative non-uniformity that evaluates the non-uniformity of one platen relative to the other platen. At least one compensation sheet of varying thickness is defined and manufactured to compensate for the non-uniformity of the upper and / or lower platens during the pressing process.

[0012] Non-uniformity of the upper platen relative to the lower platen refers to the non-uniformity of the distance between the two platens (across the platen surfaces).

[0013] Compensation sheets can be added directly to the upper and / or lower platens or at another location in the setup. Because thickness varies, the compensation sheets locally add thickness to the upper or lower platen, compensating for the relative unevenness of the platens. Thus, the compensation sheets flatten the platens so they function as if they were perfectly flat and parallel. As a result, the compensation sheets ensure that the pressure of the press station is applied evenly to all surfaces of the upper and lower platens.

[0014] In particular, the core concept of the present invention is to ensure that the corrugated board will be properly cut for any pressure setting on the machine by ensuring uniform pressure distribution, regardless of the layout of the knives used to cut and / or crease the board, i.e., the processing layout. Therefore, the compensating sheet is a sheet whose thickness compensates for non-uniformities according to a compensation layout that is independent of the processing layout. In other words, the sheet thickness compensation is performed at a position on the platen surface that is independent of the position of the knives used to process the board. Therefore, the compensation layout is independent of (i.e., generally inconsistent with) the corrugated board processing layout as traditionally done in the prior art. In this way, the compensation works for any cutting or creasing layout. The compensating sheet is preferably a sheet whose thickness compensates for non-uniformities across the entire sheet surface, i.e., across the surface that corresponds to the active surface of the platen. Therefore, in this case, it does not just follow the layout of the cutting knives. The active surface of the platen is the portion of the platen that can support the cutting knives. In most cases, this corresponds to the complete platen, or in some other embodiments, to an unbounded platen.

[0015] In practice, the compensating sheet may have regions of compensation thickness voids within the platen's working surface, but in that case, its ability to compensate for platen non-uniformities regardless of the position of the cutting knife is not impaired, as long as the surface covered by the regions of compensation thickness is sufficiently large and well-distributed, e.g., by uniformly or randomly distributing columns across the platen's working surface. Having columns uniformly or randomly distributed across the platen's working surface is, by design, independent of the corrugated board processing layout. The compensating thickness voids can be used for ventilation ducts for cooling purposes. They can also be used as vacuum ducts to hold the corrugated board in contact with the upper platen. Nevertheless, preferred embodiments use a compensating sheet with compensation thickness across the entire platen's working surface, except for voids associated with vacuum ducts, if any.

[0016] Thanks to the compensation sheet, the need for applying additional patches to the upper or lower platens is eliminated or at least greatly reduced, however, it is still possible to add additional patches to the compensation sheet if desired.

[0017] The compensation sheet can be made of metal, which gives it high stability, or it can be made of glass-filled resin, carbon-filled resin, paper printed with polymer ink, technical ceramic, or plastic.

[0018] According to one embodiment, the non-uniformity of the upper platen relative to the non-uniformity of the lower platen is determined for at least one, but preferably multiple, pressure setpoints of the press station. For each pressure setpoint, the method determines a required compensation thickness to compensate for the non-uniformity. This compensation varies with position on the platen surface, resulting in a compensation sheet with a varying thickness for each pressure setpoint. In practice, the compensation sheet is used for a range of pressure setpoints around the pressure used to determine the thickness profile of the compensation sheet.

[0019] The required pressure used in the press station depends on the material to be cut and / or creasing and the design of the cutting / creasing layout for the particular operation. Once the pressure setpoint is determined (in a known manner), a corresponding compensation sheet is selected and installed in the press station together with a tooling plate having this layout. Thanks to the compensation sheet, cutting or creasing can be performed without any additional compensation (or at least with a greatly reduced compensation requirement if the cutting / creasing does not meet specifications).

[0020] According to one embodiment, the non-uniformity (of the upper platen relative to the lower platen) is determined using simulation software by calculating the deformation of the upper platen and the deformation of the lower platen and comparing them. For example, this comparison can include subtracting the two deformations and retaining the vertical component of the difference. The result of the comparison is used to define the thickness of the compensation sheet. The non-uniformity is calculated for a specific operating pressure setting of the press station. The resulting pressure-dependent compensation is specific to the press station model. This depends on the materials comprising the press station and its geometric layout. Therefore, the resulting pressure-dependent compensation is the same for all press station prototypes of the same model. In other words, a model-specific compensation sheet is obtained.

[0021] According to one embodiment, the thickness of the compensation sheet can be adapted to compensate for press station tolerances, resulting in a prototype-specific compensation sheet. The compensation sheet can be defined for a particular operating pressure by measuring the non-uniformity of the upper platen relative to the lower platen, by analyzing one or more patch sheets used at that operating pressure, or by using a pressure-sensitive sheet. The resulting compensation sheet is unique to each individual press station unit.

[0022] According to one embodiment, the unevenness of the upper platen relative to the lower platen can be measured using a measurement plate. The measurement plate can include, for example, a set of supports and one or more sensors. The supports enable the press station to be placed under pressure. The sensors are configured to measure the distance between the upper and lower platens, or more generally, the distance between the moving and fixed surfaces of the press station.

[0023] According to one embodiment, the method for manufacturing a prototype-specific compensation sheet can be repeated for multiple operating pressures, resulting in multiple prototype-specific compensation sheets, each adapted to a range of operating pressures.

[0024] According to one embodiment, the method for producing a prototype-specific compensation sheet can be combined with a method for producing a model-specific compensation sheet. This combination allows the non-uniformity of a prototype for a particular press station to be measured only once using a single operating pressure, and all other compensation sheets compatible with different operating pressures can be calculated using simulation software. Thus, a first non-uniformity is determined using one of the prototype-specific methods at a first operating pressure. A second non-uniformity is calculated using simulation software at the same (first) operating pressure. The second non-uniformity is subtracted from the first non-uniformity to obtain a non-uniformity correction value, which accounts for the construction tolerances of the press station. At least one additional non-uniformity is then calculated using simulation software for an additional operating pressure. The non-uniformity correction value is added to the additional non-uniformity, and a compensation sheet is defined and manufactured, which is then associated with the additional operating pressure. This method can be repeated for any operating pressure setting.

[0025] According to one embodiment, the non-uniformity of the upper platen relative to the lower platen is measured multiple times using a measuring plate, each time using a different operating pressure of the press station, and each measured non-uniformity can then be used to manufacture a compensation sheet adapted to each operating pressure.

[0026] According to one embodiment, the non-uniformity correction values ​​described above can be used to create a correction compensation sheet that is used in addition to or superimposed on the model-specific compensation sheet, in other words, the correction compensation sheet is inserted into the press station and remains there, while the model-specific compensation sheet is selected depending on the operating pressure.

[0027] The compensation sheet(s) can be manufactured by additive or subtractive manufacturing techniques (i.e. engraving, etching, milling, etc.). For example, the compensation sheet is manufactured by 3D printing, chemical etching, laser engraving, whereby the compensation sheet is manufactured with particularly high thickness precision.

[0028] This object is further achieved by a method for setting up a corrugating machine, the method comprising the steps of providing a plurality of compensation sheets, particularly at least two different compensation sheets, for use in the corrugating machine, the compensation sheets being manufactured according to the method of the present invention described above, each compensation sheet being specific to an operating pressure used in the corrugating machine, selecting an operating pressure for operating a press station, selecting at least one compensation sheet based on the operating pressure, and overlapping the selected compensation sheet with an upper platen or a lower platen of the corrugating machine.

[0029] This object is further achieved by providing at least two sets of compensation sheets to compensate for non-uniformities of the upper platen relative to the lower platen of the press station during press operation. The system is uniquely configured for a particular individual press station unit. The system includes at least first and second sets of compensation sheets, each having zones of different thicknesses according to a compensation layout. The compensation layout defines the thickness of the sheet based on its position across its surface. The first sheet is designed according to a first compensation layout that compensates for non-uniformities between the two platens when the platens are pressed together at a first operating pressure, while the second sheet is designed according to a second compensation layout that compensates for the non-uniformities for a second, different operating pressure. The compensation layout compensates for non-uniformities over at least 10% of the operating surface of the upper or lower platen, but preferably over most, if not the entire operating surface. In other words, to be effective, compensation must exist over at least a portion (10%) of the operating surface of the platens.

[0030] Further features and advantages of the present invention can be obtained from the following description and accompanying drawings. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows a corrugated cardboard processing machine with a press station. [Figure 2] 1 shows a schematic diagram of a press station. [Figure 3] 1 shows an example of a measurement plate inserted into a press station. [Figure 4] Figure 4 shows a top view of the measurement plate. [Figure 5] 1 shows an example of a compensation sheet with a compensation layout adapted to a first operating pressure of a press station unit. [Figure 6]10 shows an example of a compensation sheet using a second compensation layout adapted to a second, different operating pressure of the same press station unit. [Figure 7] 1 shows a processing layout for cutting and scoring blanks from corrugated board. [Figure 8] FIG. 5 shows the compensation sheet for a press station using a vacuum duct. [Figure 9] FIG. 7 shows the compensation sheet of FIG. 6 for a press station using a vacuum duct. DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows a corrugating machine 10, particularly a die-cutting and / or creasing machine.

[0033] The corrugating machine 10 includes a feed station 12 in which corrugated blanks 14 to be processed are stacked.

[0034] Additionally, the corrugating machine 10 includes a press station 16 where the corrugated blanks 14 are cut or scored.

[0035] At stacking station 18 , corrugated blanks 14 can be stacked before being withdrawn from corrugating machine 10 .

[0036] The corrugated blank 14 can be moved along the machine direction using a gripper bar 20 attached to a drive chain 22 .

[0037] The press station 16 is described in more detail below.

[0038] In particular, the press station 16 includes an upper platen 24 and a lower platen 26. The upper platen 24 is disposed above the lower platen 26.

[0039] The platens 24, 26 are movable toward one another to cut or score the corrugated blank 14 positioned between the platens 24, 26.

[0040] In the exemplary embodiment, the upper platen 24 is fixed and the lower platen 26 is movable.

[0041] Tooling plates 28 (see FIG. 2) holding knives 30 may be attached to the upper or lower platens 24, 26 to cut the corrugated board blanks 14. The knives 30 are positioned across the platen surfaces to create cuts or creases 39 in the board and separate the board into blanks 41, thereby forming a working layout 37.

[0042] Instead of knives 30, tooling plate 28 may hold a creasing rule for creasing corrugated blank 14.

[0043] The other platen 24, 26 is fitted with an optional tooling plate 32 having slots or grooves that accommodate knives 30 and / or creasing rules.

[0044] The tooling plates 28, 32 are interchangeable since different production operations require different tooling plates 28, 32.

[0045] Additionally, the pressure distribution in the press station 16 during operation of the press station can vary depending on the corrugated board being processed as well as the cutter design.

[0046] Due to the high pressure exerted on the upper and lower platens 24, 26 during the cutting process, the platens 24, 26 may deform slightly as the press station 16 operates.

[0047] The unevenness is due in part to the size of the upper platen 24 and the lower platen 26, which is 1 mm2 2m from 2 The range is.

[0048] However, to ensure accurate cutting, the accuracy of the distance between the platens 24, 26 during pressing must be in the range of tens of micrometers.

[0049] Therefore, it is necessary to compensate for any non-uniformity in the upper platen 24 relative to the lower platen 26 to ensure an accurate cut.

[0050] For this purpose, at least one compensation sheet 34 is provided. The compensation sheet can be allocated to either the upper platen 24 or the lower platen 26, with equal effect on cutting, as shown in Figure 2. In most embodiments, there will be only a single compensation sheet 34 in one of the positions shown in Figure 2, and no sheet in the other of the positions shown.

[0051] In FIG. 2, the compensation sheet 34 appears as a flat plate for simplicity and because the thickness variation is very small compared to the size of the sheet, but to compensate for non-uniformities in the platens 24, 26, the compensation sheet 34 has a varying thickness as shown in FIGS. 5, 6, 8, or 9.

[0052] In an embodiment, a compensation sheet 34 is assigned to the upper platen 24 and is positioned between the platen and the tooling plate 28 .

[0053] The compensating sheet 34 has a high stability and can be made of, for example, steel.

[0054] The compensation sheet 34 is manufactured, for example, by additive manufacturing techniques or engraving.

[0055] The compensation sheet 34 compensates for platen nonuniformities with a compensation layout 35 that covers the entire working surface of the platens 24, 26, i.e., the surface portion available for processing corrugated board, resulting in a set of blanks 41 (which in most embodiments corresponds to the complete platen surface). Ideally, the thickness is defined at every location on the sheet across the entire working surface of the platens. In practice, compensation will work even if a portion of the surface is missing, as long as that surface is surrounded by compensation elements. In other words, the compensation sheet can be made of "pillars" whose thickness spans the entire platen surface. The pillars should cover at least 10% of the working surface of the platens and extend across the entire surface (i.e., not concentrated on one side). Preferably, they should cover 25% to 100% of the working surface. Figure 5 shows an example in which the thickness is defined everywhere across the sheet surface (i.e., the compensation thickness covers 100% of the working surface).

[0056] In an exemplary embodiment, the compensating sheet 34 is designed based on simulation, specifically using the finite element method.

[0057] More precisely, the method for providing the compensation sheet 34 can involve simulating the unevenness of the upper and lower platens 24, 26 of the press station 16 during the pressing process using simulation software. The simulation software takes into account the physical characteristics of the platens as well as the locations of the pressure points, i.e., the points where the creasing machine applies pressure to the platens or where the platens are held. The simulation is performed at a given operating pressure. The operating pressure is converted to a pressure per unit surface, taking into account the entire (usable) surface of the platens 24, 26. The simulation assumes that this pressure per unit surface is applied uniformly to every point on the platens 24, 26 and calculates the deformation of each platen 24, 26. By subtracting this deformation, or equivalently, by calculating the change in distance between the two platens deformed according to the calculation and retaining the vertical component of the deformation, a value is obtained at each location on the platen surface. This value corresponds to the thickness of the compensation sheet 34 at that location.

[0058] Based on the results of the simulation, a compensating sheet 34 of varying thickness is calculated and then manufactured to compensate for the combined deformation of the upper and lower platens 24 and 26 during the pressing process.

[0059] In particular, the compensation sheet 34 has a basic thickness required for sufficient stability of the compensation sheet 34. The varying thickness required to compensate for non-uniformities in the upper platen 24 relative to the lower platen 26 can be added to the basic thickness by additive manufacturing. Conversely, the varying thickness required to compensate for non-uniformities in the upper platen 24 relative to the lower platen 26 can be obtained by removing material from the basic thickness, for example, by laser engraving.

[0060] The relative non-uniformity of the upper and lower platens 24, 26 is calculated as a function of pressure. Preferably, multiple sheets are produced for each corrugating machine prototype, with each sheet 34, 34' associated with a particular operating pressure.

[0061] When calculating the thickness of the compensation sheets 34, 34', the mechanical tolerances of the cardboard processing machine 10 can also be taken into account, and the compensation sheets 34, 34' are calculated to compensate not only for pressure-induced deformations but also for the mechanical tolerances of the cardboard processing machine 10.

[0062] In the exemplary embodiment shown in FIG. 3, the non-uniformity of the upper platen relative to the lower platen is measured using a measurement plate 50. The measurement plate includes a structure 58 designed to support pressure and at least one sensor 52 configured to measure the distance between the two platens 24, 26. As shown in FIG. 3, the structure 58 designed to support pressure can be constructed using materials similar to standard setting tools, but without the use of cutting knives. The sensors can be a sensor pair 54, 56, each measuring the distance from the sensor to one of the platens 24, 26. The measurement plate 50 is introduced into the press unit 16 and pressed at a selected operating pressure. By displacing the sensor between the structure 58, a sampling of the distance between the two platens 24, 26 across the entire platen surface is obtained, i.e., the non-uniformity of the upper platen 24 relative to the lower platen 26 at that operating pressure is obtained. The measurement can be repeated for several operating pressure settings. Preferably, only measurements are performed at a single operating pressure. Instead of using a displaceable sensor 52, a set of fixed sensors can also be provided. The sensor may be a laser triangulation sensor, an inductive sensor, a capacitive sensor, a lidar, or a mechanical probe.

[0063] In another exemplary embodiment, the non-uniformity of the upper platen relative to the lower platen is estimated by collecting a set of patch sheets 38, consisting of at least one sheet, but preferably several sheets. These sheets 38 are created by trial and error using the press station 16 of the dye-cutting machine 10 in a conventional manner. The set of sheets 38 is selected so that all sheets are used with (approximately) the same operating pressure. A typical patch sheet includes a drawing of the cutting knife layout. The patches are color-coded, with each color corresponding to an added thickness. Thus, at each point in the layout, there is either no thickness correction if there is no patch or a thickness correction corresponding to the patch color. Outside of the layout, there is no information about the correction to be applied. By averaging the sheets in the set and interpolating where there is missing information (thickness), a thickness layout for producing the compensation sheet 34 is obtained.

[0064] In another exemplary embodiment, the non-uniformity of the upper platen 24 relative to the lower platen 26 is measured using a pressure sheet. The pressure sheet is set under pressure in a press station using a cutting or creasing tool with many contact points. The pressure sheet typically uses a color code to indicate the pressure at every contact point. From there, a pressure correction is calculated to achieve a constant pressure at every contact point (constant point), and the pressure correction is converted to added thickness. This can be done by using empirical formulas developed by trial and error, or, if the pressure measurements are well calibrated, by using the simulation software described above.

[0065] In another exemplary embodiment, the non-uniformity of the upper platen 24 relative to the lower platen 26 is determined using a plate with a large number of pillars. When the sheet is placed under pressure, the pillars deform and can be measured with an offline measurement device or reproduced by a molding operation. This embodiment can be used at multiple operating pressures (however, the pillars are permanently deformed so each prototype can only be used once). The pillars can be made of a soft metal, such as copper, aluminum, or lead.

[0066] In a preferred embodiment, the method for providing the compensation sheet 34 involves simulating the deformation of the upper platen 24 and the deformation of the lower platen 26 of the press station 16 during the pressing process for several operating pressures using simulation software, and combining the results with a method for providing the compensation sheet 34 to compensate for mechanical tolerances. To do so, a first non-uniformity is determined using one of the methods for compensating for mechanical tolerances described above. A second non-uniformity (i.e., deformation in this case) is calculated for the same (first) operating pressure using simulation software. The second non-uniformity is then subtracted from the first non-uniformity to obtain a compensated non-uniformity. Note that if the selected (first) operating pressure is close to zero, the second non-uniformity may be zero. To calculate the compensation sheet 34, 34′, the method uses simulation software to calculate the non-uniformity of the upper platen 24 relative to the lower platen 26 for several operating pressures, as described above. Each non-uniformity is then corrected by adding a correction non-uniformity to obtain a thickness layout 35, 35' (60, 62, 64, 66, 68, 69), called the compensation layout, to create a compensation sheet 34, 34' for each operating pressure in question.

[0067] Alternatively, a separate compensation sheet 34, 34' can be manufactured using the corrective non-uniformity, and another sheet can be manufactured using simulation software alone. In this case, two sheets are used at the press station 16. The separate compensation sheet, which compensates for the press station tolerances, is superimposed on one of the pressure-dependent compensation sheets 34, 34', which compensates for the pressure-dependent non-uniformity of the press station model. The latter is changed when the operating pressure changes, while the former remains in the press station.

[0068] To set up the corrugating machine, a plurality of compensation sheets 34, 34' are provided for use in the corrugating machine 10, the compensation sheets 34, 34' being manufactured according to the method described above.

[0069] In a preferred embodiment, each of the multiple compensation sheets 34, 34' is configured for a pressure range near the operating pressure. For example, a first compensation sheet 34 for an operating pressure of 400 kilonewtons (kN) can accommodate pressures ranging from 0 to 1 meganewton (MN), and a second sheet 34' for an operating pressure of 1.6 MN can accommodate pressures ranging from 1 MN to the maximum pressure allowed by the press station. The appropriate sheet is then used in the converting machine depending on the pressure required for the converting job. For example, if a converting job requires a pressure of 800 kN, the first sheet 34 described above is introduced into the platen press for that job. Note that more than two sheets can be provided per press station unit if a finer sampling of operating pressures is required.

[0070] In a preferred embodiment, the compensation sheets 34, 34' are made of glass-filled resin and are manufactured by engraving, for example using laser engraving.

[0071] The compensation sheets 34, 34' have a varying thickness, as shown in Figures 4 and 5. Each zone 60, 62, 64, 66, 68, 69 has a different thickness, with the thickness of one zone differing from the thickness of another zone in steps of, for example, 20, 35, or 50 microns.

[0072] An operating pressure for operating the press station 16 and tooling plates 28, 32 for operating the press station 16 are selected.

[0073] After selecting the operating pressure, a compensation sheet 34 is selected based on the operating pressure. If no compensation sheet 34 is available for the desired operating pressure, a compensation sheet 34 made for the closest operating pressure can be selected.

[0074] The selected compensation sheet 34 is placed against the upper platen 24 or the lower platen 26 of the corrugating machine 10 .

[0075] If the cut is still not accurate enough after adding the compensation sheet 34, it is possible to add more patches 36 to the press station, as shown in FIG.

[0076] In the illustrated embodiment, the patches 36 are assigned to the upper platen 24 , although the patches 36 could also be assigned to the lower platen 26 .

[0077] To facilitate handling of the patch 36, the patch may be applied to a patch sheet 38 which is superimposed on the compensation sheet 34.

[0078] Optionally, a separate plate 40 is provided to support the tooling plates 28, 32 and / or the compensation sheet 34.

[0079] Additionally, an optional support plate 42 is attached to the lower platen 26 .

[0080] In one embodiment, a set of at least two compensation sheets 34, 34', as shown in FIGS. 5 and 6, is provided to compensate for non-uniformities in the upper platen 24 relative to the lower platen 26 of a press station unit 16 during pressing. The system is uniquely configured for a particular individual press station unit 16. The system includes at least a first set of compensation sheets 34 and a second set of compensation sheets 34', each having zones of varying thickness 60, 62, 64, 66, 68, and 69, respectively, according to a compensation layout 35, 35'. The compensation layout defines the thickness of the sheet based on its position across its surface. The first sheet 34 is designed according to a first compensation layout 35 that compensates for non-uniformities between the two platens 24, 26 when the platens are pressed together at a first operating pressure, and the second sheet 34' is designed according to a second compensation layout 35' that compensates for the non-uniformities for a second, different operating pressure. In the example of Figures 5 and 6, the compensation layout 35, 35' compensates for non-uniformities across the entire working surface of the upper or lower platen.

[0081] In one embodiment, the set of compensation sheets shown in Figures 8 and 9 includes holes 43 that allow the press station to apply vacuum to hold the sheets on the platens before the pressing operation, or to ensure that the cardboard sticks to the appropriate platen after the pressing operation. The holes are located in specific locations in the compensation layout that correspond to the vacuum ducts in the platens, and therefore these locations are the same for sheets 34 and 34'.

[0082] A set of at least two compensation sheets 34, 34' can be used to significantly increase the productivity of conventional machines 10 already installed and operating in industry. This eliminates the need for "patching" i.e., applying patching bands through a lengthy trial and error process that must be performed manually for each individual processing job on these machines. [Explanation of symbols]

[0083] 10. Corrugated cardboard processing machine 16 Press Station Unit 24 Upper Platen 26 Lower Platen 34 Compensation Sheet

Claims

1. 1. A method for providing compensation sheets (34) for a press station (16) of a corrugating machine (10) for converting corrugated board according to a converting layout (37), said converting layout (37) defining the shape of a blank (41) to be processed by said corrugating machine, in particular a die-cutting machine and / or a creasing machine, said method comprising: determining the non-uniformity of the upper platen (24) relative to the lower platen (26) of the press station (16) during the press process; providing at least one compensation sheet (34) of varying thickness to compensate for said non-uniformity of said upper platen (24) relative to said lower platen (26) during said pressing process; manufacturing at least one respective compensation sheet (34); Including, the thickness of the compensation sheet (34) compensates for the non-uniformity according to a compensation layout (35) that defines the thickness of the sheet based on position across the surface of the compensation sheet (34); The method, wherein the compensation layout (35) is independent of the processing layout (37) of the cardboard, such that the compensation layout is independent of the shape of the blank (41) processed by the cardboard processing machine.

2. The method of claim 1 , wherein the compensation layout (35) compensates for the non-uniformity over at least 10% of a working surface of the upper platen (24).

3. The method of claim 1 or 2, wherein the compensation layout (35) compensates for the non-uniformity across a majority of the working surface of the upper platen (24).

4. The method of any one of claims 1 to 3, wherein the non-uniformity of the upper platen (24) relative to the lower platen (26) is determined as a function of pressure.

5. 5. The method according to claim 4, wherein the method is applied for at least two operating pressure setpoints of the press station (16) to produce at least two compensation sheets (34, 34') according to two different compensation layouts (35, 35'), each of the compensation sheets (34, 34') adapted to an operating pressure range around the two operating pressure setpoints.

6. 6. The method of claim 1, wherein the non-uniformity is determined by measuring a vertical component of deformation of the upper platen (24) relative to the lower platen (26), the vertical component corresponding to a thickness variation across the compensation layout (35) of the compensation sheet (34).

7. 7. The method of claim 1, wherein the non-uniformity is determined by calculating the deformation of the upper platen (24) and the deformation of the lower platen (26) using simulation software.

8. 7. The method of claim 6, wherein the vertical component of the deformation of the upper platen (24) is subtracted from the vertical component of the deformation of the lower platen (26) to correspond to the thickness change of the compensation sheet (34).

9. 9. The method according to any one of claims 1 to 8, wherein the thickness of the compensation sheet (34) is adapted to compensate for tolerances of the pressing station (16).

10. The method of claim 9, wherein the non-uniformity of the upper platen (24) relative to the lower platen (26) is measured using a measurement plate (50).

11. 11. The method of claim 10, wherein the measurement plate (50) comprises a structure (58) designed to support pressure and at least one sensor (52) configured to measure the distance between two platens (24, 26).

12. 10. The method of claim 9, wherein the non-uniformity of the upper platen (24) relative to the lower platen (26) is measured using a plate with multiple pillars that undergoes plastic deformation during the pressing process.

13. 10. The method of claim 9, wherein the non-uniformity of the upper platen (24) relative to the lower platen (26) is determined by using a pressure sensitive sheet and analyzing the pressure sensitive sheet after the pressing process.

14. 10. The method of claim 9, wherein the non-uniformity of the upper platen (24) relative to the lower platen (26) is determined by analyzing at least one manually created patch sheet for a particular operating pressure of the press station (16).

15. determining a first non-uniformity in a first operating pressure of the press station (16); calculating a second non-uniformity using the simulation software for the first operating pressure; subtracting the second non-uniformity from the first non-uniformity to yield a non-uniformity correction value; calculating at least one additional non-uniformity using said simulation software for an additional operating pressure; Including, 15. The method according to any one of claims 3 to 14, wherein the non-uniformity correction value is added to the additional non-uniformity to define and manufacture a compensation sheet (34) associated with the additional operating pressure.

16. 16. The method according to any one of claims 1 to 15, wherein the compensation sheet (34) is manufactured by additive or subtractive manufacturing techniques.

17. 17. The method according to any one of claims 1 to 16, wherein the compensation sheet (34) is made of glass-filled resin and is produced by engraving.

18. A method for setting up a corrugated cardboard processing machine (10), comprising: providing a plurality of compensation sheets (34, 34') for use in the corrugating machine (10), each compensation sheet (34, 34') being specific to an operating pressure range used in a press station (16) of the corrugating machine (10); selecting an operating pressure for operating said press station (16); selecting the compensation sheet (34, 34') based on the operating pressure; overlapping the selected compensation sheet (34, 34') with the upper platen (24) or the lower platen (26) of the press station (16); Including, The compensation sheets (34, 34') are uniquely configured for a particular individual corrugating machine (10).

19. 19. The method according to claim 18, wherein the compensation sheet (34, 34') is manufactured according to the method according to any one of claims 1 to 17.

20. 1. A system designed to compensate for unevenness of an upper platen (24) relative to a lower platen (26) of a press station (16) during a pressing process, said system being uniquely configured for a particular individual press station unit (16), said system comprising: a set of at least first and second compensation sheets (34, 34'); Equipped with each of said compensation sheets having zones (60, 62, 64, 66, 68, 69) with different thicknesses according to a compensation layout (35, 35') that defines the thickness of said sheet based on position across the surface of said compensation sheet (34, 34'); the first sheet (34) is designed according to a first compensation layout (35) that compensates for non-uniformity in the distance between the upper platen (24) and the lower platen (26) of the unit (16) when the platens (24, 26) are pressed together at a first operating pressure; the second sheet (34') is designed according to a second compensation layout (35') that compensates for non-uniformity in the distance between the upper platen (24) and the lower platen (26) of the unit (16) when the platens (24, 26) are pressed together at a second operating pressure different from the first operating pressure; The system, wherein the first and second compensation layouts (35, 35') compensate for non-uniformities over at least 10% of the working surface of the upper platen (24), i.e., a set of positions within the surface of the sheet (34, 34') having compensation thicknesses covers at least 10% of the working surface of the upper platen (24).

21. The system of claim 20, wherein the layout (35, 35') compensates for the non-uniformity across a majority of the working surface of the upper platen (24).

22. 21. The system of claim 20, wherein the layout (35, 35') of the compensation sheets (34, 34') comprises holes (43) at specific positions for implementing vacuum ducts, the positions of the holes (43) being identical for each of the compensation sheets (34).

23. 21. Apparatus according to claim 20, wherein the compensation sheet (34, 34') is used to implement the method according to claim 18.

24. 21. Apparatus according to claim 20, wherein the compensation sheet (34, 34') is manufactured according to the method according to any one of claims 1 to 17.

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