Method For Correcting An Alignment Of A Cutting Layer And Cutting Machine

Abstract

A method for correcting an alignment of a cutting layer made up of stacked, sheet-format product in the form of sheets in relation to a cutting plane of a cutting blade of a cutting machine, and a cutting machine. The cutting machine has a feed saddle for displacing the cutting layer in the direction of the cutting plane of the cutting blade, wherein the feed saddle is adjustable in its alignment in relation to the cutting plane to change the alignment of the cutting layer pressing against the feed saddle in relation to the cutting plane. The respective sheet is provided with at least one cutting test mark, wherein the respective cutting test mark has a coloration changing in the feed direction of the feed saddle.

Claims

1. A method for correcting an alignment of a cutting layer made up of stacked, sheet-format product in the form of sheets in relation to a cutting plane of a cutting blade of a cutting machine, wherein the cutting machine has a table for receiving the cutting layer and a feed saddle for displacing the cutting layer in the direction of the cutting plane of the cutting blade of the cutting machine, wherein the feed saddle is adjustable in its alignment in relation to the cutting plane to change the alignment of the cutting layer pressing against the feed saddle in relation to the cutting plane, wherein a respective sheet is provided with at least one cutting test mark, wherein the respective cutting test mark has a coloration changing in a feed direction of the feed saddle, wherein the method comprises: a) displacing the cutting layer by means of the feed saddle in the direction of the cutting plane of the cutting blade such that the cutting plane intersects the cutting test marks; b) cutting the cutting layer using the cutting blade to form a cut front side having a frontally visible colored pattern formed by the cut-through cutting test marks; c) determining a coloration of the frontally visible pattern; and d) determining whether deviations of the alignment of the cutting layer from an intended alignment are present, wherein the determination is carried out on the basis of the coloration of the frontally visible pattern, wherein upon the presence of deviations, the alignment of the feed saddle in relation to the cutting plane is changed to correct the alignment of the cutting layer.

2. The method according to claim 1, wherein the feed saddle is rotatable around a first axis extending perpendicular to a plane spanned by the table to change a rotational angle of the feed saddle with respect to the cutting plane and/or wherein the feed saddle is rotatable around a second axis extending parallel to the plane spanned by the table to change a tilt angle of the feed saddle with respect to the cutting plane.

3. The method according to claim 1, wherein the respective cutting test mark has at least two monochromatic sections arranged one behind the other in the feed direction of the feed saddle, wherein adjacent sections in the feed direction differ in their color.

4. The method according to claim 3, wherein the sections each have an extension of 0.05 mm to 0.2 mm in the feed direction of the feed saddle.

5. The method according to claim 3, wherein adjacent sections in the feed direction are arranged offset in relation to one another in a transverse direction extending transversely to the feed direction.

6. The method according to claim 1, wherein to determine whether deviations of the alignment of the cutting layer from an intended alignment are present, the determined coloration is compared to an intended coloration corresponding to the intended alignment of the cutting layer, wherein upon deviation of the determined coloration from the intended coloration, the alignment of the feed saddle in relation to the cutting plane is changed.

7. The method according to claim 2, wherein upon the presence of a change of the coloration of the pattern in a stack direction of the cutting layer, a required correction of the tilt angle of the feed saddle is determined.

8. The method according to claim 2, wherein the respective sheet is provided with a first cutting test mark and an identical second cutting test mark, wherein the first cutting test mark and the second cutting test mark are spaced apart from one another in a transverse direction extending transversely to the feed direction, wherein the cut-through first cutting test marks form a first frontally visible pattern and the cut-through second cutting test marks form a second frontally visible pattern, wherein the coloration of the first frontally visible pattern is compared to the coloration of the second frontally visible pattern, and the required correction of the rotational angle of the feed saddle is determined from the result of the comparison.

9. The method according to claim 8, wherein to determine the required correction of the rotational angle of the feed saddle at a specific height in a stack direction, a color value of the coloration of the first frontally visible pattern is determined and, at the same height in the stack direction as in the first frontally visible pattern, a color value of the coloration of the second frontally visible pattern is determined, wherein the required correction of the rotational angle of the feed saddle is determined from a comparison of a distance of the first cutting test mark and the second cutting test mark from one another in the transverse direction to a distance of the positions of the corresponding color values in the first and second cutting test marks in the feed direction.

10. The method according to claim 9, wherein the frontally visible pattern or frontally visible patterns are acquired by means of at least one image sensor and are transmitted to an evaluation device, wherein the evaluation device is configured to determine the coloration of the frontally visible pattern or frontally visible patterns in a computer-assisted manner and/or to determine the required correction of the rotational angle of the feed saddle in a computer-assisted manner and/or to determine the required correction of the tilt angle of the feed saddle in a computer-assisted manner.

11. The method according to claim 10, wherein the evaluation device is configured to compare the determined coloration to the intended coloration corresponding to the intended alignment and to determine the required correction of the rotational angle of the feed saddle and/or the required correction of the tilt angle of the feed saddle from the result of the comparison.

12. A cutting machine for cutting a cutting layer made up of stacked, sheet-format product in the form of sheets, wherein a respective sheet is provided with at least one cutting test mark, wherein the cutting machine has a table for receiving the cutting layer, a cutting blade, and a feed saddle for displacing the cutting layer in the direction of a cutting plane of the cutting blade of the cutting machine, wherein a respective cutting test mark has a coloration changing in the feed direction of the feed saddle, wherein the cutting machine has an adjustment device for adjusting an alignment of the feed saddle in relation to the cutting plane, for changing an alignment of the cutting layer pressing against the feed saddle in relation to the cutting plane, wherein the cutting machine has a system for determining and correcting any deviations of the alignment of the cutting layer from an intended alignment of the cutting layer, wherein the system has at least one image sensor, wherein the image sensor is configured, after a cut-through the cutting test marks, to acquire a frontally visible colored pattern formed by the cut cutting test marks, wherein the system has an evaluation device, wherein the evaluation device is configured to determine on the basis of a coloration of the frontally visible colored pattern whether deviations of the alignment of the cutting layer from the intended alignment are present, and wherein the system is configured, upon the presence of deviations, to adjust the feed saddle in its alignment in relation to the cutting plane by activating the adjustment device in order to correct the alignment of the cutting layer pressing against the feed saddle in relation to the cutting plane.

13. The cutting machine according to claim 12, wherein the feed saddle is rotatable around a first axis extending perpendicular to a plane spanned by the table to change a rotational angle of the feed saddle with respect to the cutting plane and/or wherein the feed saddle is rotatable around a second axis extending parallel to the plane spanned by the table to change a tilt angle of the feed saddle with respect to the cutting plane.

14. The cutting machine according to claim 13, wherein the evaluation device is configured to evaluate the frontally visible colored pattern acquired by the image sensor in a computer-assisted manner in order to determine the required correction of the tilt angle of the feed saddle and/or the required correction of the rotational angle of the feed saddle in a computer-assisted manner.

15. The cutting machine according to claim 12, wherein the evaluation device is configured to compare the determined coloration to an intended coloration, which is stored in a memory of the evaluation device and corresponds to the intended alignment of the cutting layer, wherein the system is configured to activate the adjustment device based on the result of the comparison to correct the alignment of the cutting layer pressing against the feed saddle in relation to the cutting plane.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0085] The invention will be explained in more detail with reference to the following figures on the basis of exemplary embodiments, without being restricted thereto.

[0086] FIG. 1 shows a schematic representation of a cutting machine according to the invention in a sectional view along line I-I in FIG. 2.

[0087] FIG. 2 shows the cutting machine according to the invention in a view according to arrow II in FIG. 1.

[0088] FIG. 3 shows a partial area of the cutting machine according to FIG. 1 in a view from above.

[0089] FIG. 4 shows a partial area of the cutting machine according to FIG. 1 in a perspective view diagonally from the side.

[0090] FIG. 5 shows a schematic representation of a sheet to be cut of a cutting layer in a view from above, wherein the sheets are each printed with a cutting test mark according to a first embodiment.

[0091] FIG. 6 shows two areas of a cut front side of the product to be cut with intended alignment of the cutting layer.

[0092] FIG. 7 shows a view as in FIG. 6 with incorrect alignment of the cutting layer with respect to the rotational position.

[0093] FIG. 8 shows a view as in FIG. 6 with incorrect alignment of the cutting layer with respect to the tilt position.

[0094] FIG. 9 shows a view as in FIG. 6 with incorrect alignment of the cutting layer with respect to the rotational position and with respect to the tilt position.

[0095] FIG. 10 shows a schematic representation of the cutting layer with an alignment error according to FIG. 7 in a view from above.

[0096] FIG. 11 shows a schematic representation of the cutting layer with an alignment error according to FIG. 8 in a side view.

[0097] FIG. 12 shows a schematic representation of a sheet to be cut of a cutting layer in a view from above, wherein the sheets are each printed with a cutting test mark according to a second embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0098] FIG. 1 shows a cutting machine 1 according to the invention, which is used to cut a cutting layer 2 of stacked, sheet-format product in the form of sheets. The sheets can be sheets made of paper, paperboard, film, or the like. The cutting layer 2 is present in cuboid form and has a stack height H.

[0099] The cutting machine 1 has a table 3 having an upper, horizontal table surface 12. In FIG. 2, the table surface 12 extends perpendicular to the plane of the drawing sheet, thus in or parallel to the X-Y plane. A cutting blade 6 that can be lowered and raised is mounted in a portal frame (not shown in more detail), wherein a pressing bar 8 is mounted so it can be raised and lowered, also in the portal frame, in front of the cutting blade 6. The pressing bar 8 is used for fixing the cutting layer 2, in that the pressing bar 8 presses the cutting layer 2 against the table 3 in the lowered position, as shown in FIG. 1. The cutting blade 6 is movable in the swing cut by means of a crank drive (not shown in more detail) from an upper end position into a lower end position, in which it penetrates into a cutting bracket 9 received by the table 3. FIG. 1 shows the cutting blade 6 in a state between the first end position and the second end position. The cutting blade 6 is mounted in the present case in a so-called blade bar 7 of the cutting machine 1, wherein this blade bar 7 is movable from the first end position into the second end position and is used to transfer the cutting movement to the cutting blade 6.

[0100] In the area of the rear table part, thus on the left in FIG. 1, a feed saddle 4 is provided, which has a front rake section 10. This rake section 10 presses against the cutting layer 2 at the end facing away from the cutting blade 6. The feed saddle 4 is used to displace the cutting layer 2 in the direction of a cutting plane 5 of the cutting blade 6. The cutting plane 5 is in the present case in or parallel to the Y-Z plane. The feed saddle 4 is rotatable around a vertical axis 13 to change an alignment of the cutting layer 2, namely a rotational position of the cutting layer 2, in relation to the cutting plane 5 of the cutting blade 6, as is schematically indicated by the arrow 23 in FIG. 3. Furthermore, the feed saddle 4 is rotatable around a horizontal axis 14 to change an alignment of the cutting layer 2, namely a tilt of the cutting layer 2, in relation to the cutting plane 5 of the cutting blade 6, as is schematically indicated by the arrow 24 in FIG. 4. The cutting machine 1 has an adjustment device (not shown in more detail) for rotating and tilting the feed saddle 4.

[0101] The cutting machine 1, more precisely the table 3, has two opposite lateral stops 22, which are used to contact the cutting layer 2. The cutting layer 2 can be manually oriented by means of a straight edge 11, in particular pressed against one of the lateral stops 22.

[0102] An upper side 21 of a sheet of the cutting layer 2 is shown in FIG. 5. The sheets are printed with a printed image, in the present case in the form of squares, which are to be exposed by corresponding cutting. In order to obtain the desired cutting picture, it has to be ensured that the alignment of the cutting layer 2 in relation to the cutting plane 5 corresponds to an intended alignment. For this purpose, in addition to the actual printed image, two cutting test marks 16 according to a first exemplary embodiment, as schematically shown in FIG. 5, are printed on the respective sheet of the cutting layer 2. These cutting test marks 16 were printed together with the printed image. The extension of the cutting test marks 16 is typically only fractions of millimeters in the longitudinal direction X and several millimeters in the transverse direction Y. In contrast, the uncut sheet typically has an extension of greater than 100 cm in the longitudinal direction X and of greater than 100 cm in the transverse direction Y. For reasons of better comprehension, the cutting test marks 16 are not shown to scale in FIG. 5, but rather greatly enlarged. The two cutting test marks 16 have a distance D in the transverse direction Y. The respective cutting test mark 16 has multiple monochromatic sections 16a, 16b, 16c arranged one behind another in the feed direction X of the feed saddle 4 and adjoining one another, wherein adjacent sections 16a, 16b, 16c differ in their color. In the present case, the first section 16a is black, the second section 16b is yellow, and the third section 16c is red. In each case a cutting test marks 16 having a coloration changing in the feed direction X of the feed saddle 4 thus results, namely from black to yellow to red. The respective section 16a, 16b, 16c is rectangular. The longitudinal extension A of the sections 16a, 16b, 16c in the feed direction X are identical and are fractions of millimeters, in the present case each 0.1 mm. Accordingly, center lines of adjacent sections 16a, 16b, 16c have a distance which is identical to the extension of the sections. Transversely to the feed direction X, namely in the transverse direction Y, the sections 16a, 16b, 16c differ in their extension, therefore in their transverse extension. In the present case, the first section 16a has a transverse extension of approximately 1 cm. The transverse extension of the second section 16b is approximately twice as large as the transverse extension of the first section 16a and the transverse extension of the third section 16c is approximately twice as large as the transverse extension of the second section 16b. The respective cutting test mark 16 therefore also has, in addition to a coloration changing in the feed direction X of the feed saddle 4, a cross section changing in the feed direction X, wherein the cross section changes in steps in the present case. Any deviations of the alignment of the cutting layer 2 from the intended alignment of the cutting layer 2 can be determined by a test cut through the cutting test marks 16 executed using the cutting machine 1, as will be explained in more detail hereinafter.

[0103] The cutting machine 1 has a system for determining and correcting any deviations of the alignment of the cutting layer 2 in relation to the cutting plane 5 from the intended alignment of the cutting layer 2 in relation to the cutting plane 5. The system has two cameras, wherein the respective camera has an image sensor 17 for optically acquiring a cut front side 18 of the cutting layer 2 after carrying out a test cut. The two cameras are displaceable in the transverse direction Y and are connected by means of a bearing structure 20 to the cutting machine 1, in the present case the portal frame.

[0104] To determine possible deviations in the alignment of the cutting layer 2 in relation to the cutting plane 5, the cutting layer 2 is displaced by means of the feed saddle 4 in the direction of the cutting plane 5 of the cutting blade 6 such that the cutting plane 5 intersects the cutting test marks 16. This state is schematically shown in FIG. 5. Upon a cut using the cutting blade 6, the cutting layer 2 is cut through in the area of the cutting test marks 16, due to which a cut front side 18 of the cutting layer 2 having two frontally visible colored patterns 19, which are spaced apart in the transverse direction Y by the distance D, formed by the cut cutting test marks 16 is formed. Any deviations in the distance D caused by alignment errors are generally negligible.

[0105] The image sensor 17 is configured, after a cut through the cutting test marks 16, also designated as a test cut, to acquire the frontally visible colored pattern 19 formed by the cut cutting test marks 16, wherein the system has an evaluation device 15, wherein the evaluation device 15 is configured to determine on the basis of a coloration of the acquired patterns 19 whether deviations of the alignment of the cutting layer 2 from the intended alignment are present, and wherein the evaluation device 15 is configured, upon the presence of deviations, to adjust the feed saddle 4 in its alignment in relation to the cutting plane 5 by activating the adjustment device, namely to rotate it around the axis 13 and/or around the axis 14, in order to correct the alignment of the cutting layer 2 pressing against the feed saddle 4 in relation to the cutting plane 5 in a suitable manner.

[0106] The coloration of the respective pattern 19 is dependent on the position at which the cutting test marks 16 were cut through in the feed direction X. If the cutting test mark 16 is cut through in the area of the first black section 16a, in the pattern, a black area 19a corresponding to the first section 16a results in the pattern 19. Accordingly, upon a cut through the second yellow section 16b, a yellow area 19b results and upon a cut through the third section 16c, a red area 19c results in the pattern 19. Upon exact alignment of the cutting layer 2 in relation to the cutting plane 5, the cutting test marks 16 are located flush one over another in the direction of the cutting plane 5. This corresponds to the intended alignment of the cutting layer 2 in relation to the cutting plane 5. If a cut is carried out through the cutting layer 2 in the intended alignment, a monochromatic pattern 19 results, since all cutting test marks 16 were cut through at the same position in the feed direction X. If the black section 16a is brought into the cutting plane 5, as shown in FIG. 5, a pattern 19 which only consists of a black area 19a accordingly results with intended alignment of the cutting layer 2. An intended coloration corresponding to the intended alignment is thus monochromatic black in the present case.

[0107] Exemplary cutting patterns 19 for a cutting layer 2, which consists of a plurality of sheets stacked one on top of another, are schematically shown in FIGS. 6 to 9 for different alignments of the cutting layer 2 in relation to the cutting plane 5. For reasons of clarity, the individual sheets, in general several hundred to several thousand sheets stacked one on top of another, are not shown resolved in FIGS. 6 to 9. The respective sheet corresponds to the sheet shown in FIG. 5 and accordingly has two cutting test marks 16 spaced apart in the transverse direction Y. FIGS. 6 to 9 each show two areas of the front side 18 of the cut cutting layer 2 spaced apart in the transverse direction Y, each of which shows a pattern 19 formed by the cut-through cutting test marks 16.

[0108] FIG. 6 shows the result of a cut through a cutting layer 2 in which the alignment of cutting layer 2 in relation to the cutting plane 5 corresponds to the intended alignment of the cutting layer 2 in relation to the cutting plane 5. The alignment of the cutting plane 5 in relation to the cutting test marks 16 in the feed direction X was selected in the test cut such that the cutting blade 6 has cut through the cutting test mark 16 of the uppermost sheet approximately in the middle of the first section 16a, as schematically shown in FIG. 5. After the cut, in this case, therefore a case without deviations of the alignment from an intended alignment, the two cut-through cutting test marks 16 form identical frontally visible colored patterns 19, wherein the respective pattern 19 has no color changes or cross-sectional changes in the vertical direction Z, which in the present case is identical to the stack direction of the cutting layer 2. Since the cut has taken place through the first section 16a, the coloration of the respective pattern 19 is identical to the color of the first section 16a. The respective pattern 19 therefore only has a black area 19a. The coloration of the pattern 19 therefore corresponds to the intended coloration.

[0109] FIGS. 7 to 9 show cutting patterns 19 upon deviations from the intended alignment of the cutting layer 2 with respect to the cutting plane 5. FIG. 7 shows an incorrect alignment, wherein this incorrect alignment is that the cutting layer 2 is tilted in relation to the cutting plane 5 with respect to the axis 13 by a rotational angle ?, as schematically shown in FIG. 10. The cutting patterns 19, which are shown in FIG. 7 and are formed by the identical cutting test marks 16, are different in their coloration. The left pattern 19 exclusively has a black area 19a and the right pattern 19 exclusively has a yellow area 19b. This difference results in that due to the incorrect alignment of the cutting blade 6, the cutting test mark 16 forming the respective pattern 19 has not been cut through in identical sections, but rather the cutting test mark 16 forming the left pattern 19 was cut through in the first black section 16a and the cutting test mark 16 forming the right pattern 19 was cut through in the second yellow section 16b, as can also be seen from FIG. 10. Moreover, the two patterns 19 differ in their dimension in the transverse direction Y. This difference is because the first section 16a has a lesser extension in the transverse direction Y than the second section 16b. The correction of the alignment of the cutting layer 2 can be carried out by rotating the feed saddle 4 around the axis 13. Since the two patterns 19 are monochromatic, there is no tilt error. The rotational angle ? and thus the required rotational angle correction can be calculated via the following relationship:

[00004]$?=\arctan \frac{X\left(\mathrm{black}\right)-X\left(\mathrm{yellow}\right)}{D}=\frac{A}{D}$ [0110] wherein [0111] ?: required rotational angle correction or angle deviation in the rotation; [0112] X (black): position of the color black in the feed direction X; [0113] X (yellow): position of the color yellow in the feed direction X; [0114] D: distance between the first cutting test mark and the second cutting test mark in the transverse direction Y; and [0115] A: longitudinal extension of the sections.

[0116] FIG. 8 shows a different incorrect alignment, wherein this incorrect alignment is that the cutting layer 2 to be cut is tilted in relation to the cutting plane 5 with respect to the axis 14 by the tilt angle ? insofar as is incorrect in its tilt with respect to the cutting plane 5, as schematically shown in FIG. 11. In the present case, the respective pattern 19 has a cross section changing in steps in the vertical direction Z having three steps of different colors, wherein the cross section of the steps increases from bottom to top and the lowermost step is black, the middle step is yellow, and the uppermost step is red. It may be concluded from the coloration of the pattern 19 that the cut cutting layer has a tilt error in the form of an undercut. A correction of the alignment can be carried out by rotating the feed saddle 4 around the axis 14 by the angle ?. Since the two patterns 19 are identical, there is no error in the rotational position of the cutting layer 2. The tilt angle q and therefore the tilt angle correction can be calculated in good approximation via the following relationship:

[00005]$?=\arctan \frac{X\left(\mathrm{black}-\mathrm{yellow}\right)-X\left(\mathrm{yellow}-\mathrm{red}\right)}{Z\left(\mathrm{black}-\mathrm{yellow}\right)-Z\left(\mathrm{yellow}-\mathrm{red}\right)}=\arctan \frac{A}{Z\left(\mathrm{black}-\mathrm{yellow}\right)-Z\left(\mathrm{yellow}-\mathrm{red}\right)}$ [0117] wherein [0118] ?: required tilt angle correction or angle deviation in the tilt; [0119] Z (black-yellow): position of the boundary between the color black and the color yellow in the stack direction Z; [0120] Z (yellow-red): position of the boundary between the color yellow and the color red in the stack direction Z; and [0121] A: longitudinal extension of the sections.

[0122] In good approximation, it can be assumed that

[00006]$??\arctan \frac{\left(N-1\right)?A}{H}=\frac{2?A}{H}$ [0123] wherein [0124] ?: required tilt angle correction or angle deviation in the tilt; [0125] N: number of the areas of different color in the pattern in the stack direction; in the present case N=3; [0126] A: distance of the centers of adjacent sections in the cutting test mark in the feed direction; and [0127] H: stack height of the cutting layer.

[0128] FIG. 9 shows the frontal pattern 19 upon the presence of a combination of a tilt error and a rotation error.

[0129] FIG. 12 again shows a schematic representation of a sheet to be cut of a cutting layer 2 in a view from above analogous to FIG. 10 according to a second embodiment. The sheets are again each printed with two cutting test marks 16, wherein the cutting test marks essentially differ from the cutting test marks of the first embodiment shown in FIG. 5 in that the monochromatic sections 16a, 16b, 16c have identical width extension B in the transverse direction Y and are offset in relation to one another by the width extension B in the transverse direction Y, so that a stepped arrangement results.