Apparatus and method for measuring protrusions on surface of rotating body

Abstract

The invention relates to a device for measuring a projection on the surface of a rotating body, which is designed as a cylinder, roller, sleeve or plate for a printing press, having a first motor for rotating the rotating body about an axis of rotation, and having a measuring device, wherein the measuring device comprises at least one light source and a plurality of cameras for contactless measurement, which cameras are arranged substantially in a row oriented parallel to the axis of rotation and have respective detection regions. The measuring device comprises a first scale and a second scale, the first scale being arranged on a first side of the rotating body and the second scale being arranged on an opposite second side of the rotating body. The first scale is located at least in sections in a first detection area of the first camera and the second scale is located at least in sections in a second detection area of the second camera. The invention advantageously allows for accurate measurements in flexible printed boards or surfaces thereof with projections. The invention is used in an installer for a flexographic press stamp.

Description

Technical Field

[0001] The invention relates to a device for measuring a protrusion on the surface of a rotating body and a method for measuring a protrusion on the surface of a rotating body.

[0002] The invention belongs to the technical field of platemaking (graphics industry), in particular to the technical field of flexographic printing, i.e. to the operation of flexographic printing presses, i.e. rotary printing presses for printing with flexographic moulds, and to the operation of their peripheral equipment, in particular to the operation of so-called setters, in which a plurality of flexographic moulds are arranged ("set") on cylinders or cylinder sleeves according to the printing order. The invention relates in particular to the sub-field of precise measurement of "set" flexographic moulds, for example directly in the setter. Background Art

[0003] In the prior art of this technical field, flexographic printing machines, mounting machines and devices for measuring flexographic impressions during or after "mounting" in mounting machines are known. For example, the documents DE 10 2020 11 1 341 A1, EP 3 822 080 A1 and DE 10 2005 053 432 A1 should be mentioned. In these documents, the calibration of the measuring device used in each case is mentioned, but not explained in detail. Summary of the invention

[0004] Against this background, the object of the present invention is to improve the prior art and in particular to enable precise measurement of flexographic printing plates or surfaces thereof structured with projections or other structured printing technology surfaces, such as anilox roll surfaces.

[0005] According to the invention, this object is achieved by a device and a method having the features of preferred embodiments of the invention.

[0006] Advantageous and therefore preferred embodiments of the invention emerge from the alternative embodiments as well as from the description and the drawings.

[0007] According to the present invention, a device for measuring a protrusion on the surface of a rotating body is provided, wherein the rotating body is configured as a cylinder, roller, sleeve or plate for a printing press, wherein the device has a first motor for rotating the rotating body around a rotation axis and has a measuring device, wherein the measuring device comprises at least one light source and a plurality of cameras for non-contact measurement, wherein the cameras are basically arranged in a row oriented parallel to the rotation axis and have corresponding detection areas. The present invention proposes that the measuring device comprises a first scale and a second scale, wherein the first scale is arranged on a first side of the rotating body and the second scale is arranged on a second side opposite to the rotating body, wherein the first scale is at least partially located in a first detection area of ​​the first camera and the second scale is at least partially located in a second detection area of ​​the second camera.

[0008] According to the present invention, a method for measuring a protrusion on the surface of a rotating body is provided, the rotating body being configured as a cylinder, roller, sleeve or plate for a printing press. The present invention proposes to use a device and a computer as described in any technical solution, and to detect two scales at least in sections during the measurement process, and to determine two orientation values ​​of the row of cameras in order to perform a computational correction on the orientation of the row of cameras.

[0009] Advantageous development schemes and effects of the present invention

[0010] The invention advantageously makes possible a precise measurement of a flexographic printing plate or its surface provided with projections.

[0011] In the context of calibrating a device for measuring projections of a printing technology surface (e.g. a flexographic stamp), it may initially be necessary to orient or align an existing row of cameras relative to one another, i.e. relative to one another. This can be achieved, for example, by using a tensioned wire as described in DE 10 20 20 11 1 341 A1.

[0012] By using the invention, a row of cameras can be advantageously absolutely aligned, ie for example absolutely aligned with respect to a rotating body or its bearings or axes of rotation.

[0013] The invention is advantageously employed in the following process:

[0014] The three-dimensional profile of the die surface is measured, settings for the printing press are calculated therefrom, defects on the die are identified, and a visualization of the die is provided to the operator, preferably together with the measured and identified details.

[0015] Expansion scheme of the present invention

[0016] The following describes preferred developments of the device of the present invention (hereinafter referred to as developments). These developments can also be combined with one another if this is not technically impossible.

[0017] An extended solution may be characterized in that the two scales have size scales. An extended solution may be characterized in that the two scales are transparent, for example made of glass. An extended solution may be characterized in that the measuring device includes a first and a second mirror. An extended solution may be characterized in that the first mirror is arranged behind the first scale relative to the light source, so that the light from the light source and passing through the first scale is reflected on the first mirror and reaches at least one camera. An extended solution may be characterized in that the second mirror is arranged behind the second scale relative to the light source, so that the light from the light source and passing through the second scale is reflected on the second mirror and reaches at least one camera.

[0018] One development can be characterized in that the two scales are arranged in a first plane, in which the axis of rotation is also located. One development can be characterized in that the plane is essentially a horizontal plane.

[0019] A feature of an extended solution may be that the light source is movable.

[0020] One extended solution may be characterized in that the camera is movable. One extended solution may be characterized in that the light source and the camera are movable together. One extended solution may be characterized in that the light source and the camera are movable in a second plane substantially parallel to the first plane.

[0021] Preferred extensions of the method of the present invention (hereinafter referred to as extensions) are described below. These extensions can also be combined with one another if this is not technically impossible.

[0022] One development may be characterized in that the two position values ​​are determined (or determined) successively.

[0023] The features and feature combinations disclosed in the above technical field, summary and developments section as well as in the following exemplary embodiments section—in combination with one another in any manner—represent further developments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 and Figure 2 The preferred embodiments and developments of the present invention are shown. Corresponding features in the figures are provided with the same reference numerals.

[0025] Figure 1 A (transverse) cross-sectional view of a preferred embodiment of the device according to the invention is shown when carrying out a preferred embodiment of the method according to the invention.

[0026] Figure 2 Show Figure 1 (Longitudinal) cross-sectional view of the device shown. DETAILED DESCRIPTION

[0027] Figure 1 The rotating body 2 shown in FIG. 1 is used to measure the topography of a rotating body 2 or a rotating surface 3. The rotating body 2 has an axis of rotation 4 and is rotatably supported on both sides (a first side 7 and a second side 8) in bearings 5. During the measurement, a first motor 6 is used to drive the rotation.

[0028] At least one stamp 10 is received on the rotating body 2 directly or on a sleeve 25. The (outer) surface 11 of the stamp 10 forms at least one section of the surface 3. On the surface 11 are formed projections 12, for example the printing areas of a flexographic stamp; these projections form the topography to be measured.

[0029] The device 1 also comprises a measuring device 20. The measuring device in turn comprises a carrier 21 for a light source 22, which emits light 23, and for a row of cameras 24, which are preferably arranged adjacent to one another. The carrier 21 together with the light source 22 and the camera 25 can be moved perpendicularly to the rotation axis 4, for which purpose a linear drive 40 with a second motor 41, a spindle 42 and a spindle nut 43 can be provided.

[0030] The device 1 further comprises a first mirror 30 and a second mirror 31 , each arranged on one of the two sides 7 or 8 . The two mirrors 30 , 31 reflect the light 23 from the light source 22 to the camera 25 .

[0031] In the beam path of the reflected light 23, there is a first size scale on the first side 7. The first scale 32 of the embodiment of the present invention has a first scale 32a and a second scale 33 with a second size scale 33a on the second side 8. The two scales 32 and 33 are preferably located in a first, preferably horizontal plane 70, in which the rotation axis 4 is also located. The two scales 32 and 33 are precisely arranged, preferably with an accuracy in the micrometer range.

[0032] The device 1 also includes a tensioned (metal) wire 50. This wire can be used to first align the individual cameras 25 in the row 24 with one another, so that all cameras 25 can detect the wire 50 in their respective camera images. The wire 50 is preferably also located in the first plane 70.

[0033] The light source 22 and the camera 25 are preferably located in a second plane 71 ; the second plane is preferably arranged horizontally and parallel to the first plane 70 .

[0034] Figure 2 The device 1 shown in the figure comprises the first scale 32 and the second scale 33 on opposite sides of the rotating body 2. Figure 2 The structured surface 3 of the rotating body to be measured can be seen in FIG.

[0035] Figure 1The row 24 of cameras 25 shown in corresponds to the row 26 of (optical) detection areas 27. The first size scale 32a is detected at least in sections by the first camera 25a in its first detection area 27a. Similarly, the second size scale 33a is detected at least in sections by the second camera 25b in its second detection area 27b. Here, the first camera 25a generates a first image 60 and the second camera 25b generates a second image 61. In the first image 60, a part of the first size scale 32a can be identified (for example on the left side); in the second image 61, a part of the second size scale 33a can be identified (for example on the right side). These two size scales are preferably in the micrometer range. The other cameras 25c can also generate images 62, but no part of the size scale can be identified in these images.

[0036] The detected images, in particular the two images 60 and 61, are preferably transmitted to a computer 80 and evaluated by the computer. The computer 80 can identify the tilt position of the row 24 of the camera 25 or calculate its value (for example by using digital image processing techniques known to those skilled in the art). To this end, the position of the row 24 on the two sides 7 and 8 can be compared with the respective size scales. The tilt position is then corrected. This can be done automatically or manually. In this way, the row 24 of the camera 25 (in addition to the relative alignment between the above-mentioned cameras) can be aligned absolutely and preferably in the micrometer range. Therefore, the two scales 32 and 33 are preferably precisely (preferably perpendicular to) oriented relative to the rotation axis 3 and mounted in a fixed position.

[0037] List of reference numerals:

[0038] 1 device

[0039] 2 Rotating bodies, especially rollers

[0040] 3 Surface

[0041] 4 Rotation Axes

[0042] 5 Bearings

[0043] 6First Motor

[0044] 7 First side

[0045] 8 Second side

[0046] 10. Impression

[0047] 11 Surface

[0048] 12 Protrusion

[0049] 20 Measuring device

[0050] 21 Carrier

[0051] 22 Light Source

[0052] 23 Light Source

[0053] 24 rows

[0054] 25One / multiple cameras

[0055] 25a First Camera

[0056] 25b Second Camera

[0057] 25c Other cameras

[0058] 26 rows

[0059] 27One / multiple detection areas

[0060] 27a First detection area

[0061] 27b Second detection area

[0062] 30 First Mirror

[0063] 31 Second Mirror

[0064] 32 First Ruler

[0065] 32a First size scale

[0066] 33 Second Ruler

[0067] 33a Second size scale

[0068] 40 Linear drive

[0069] 41 Second Motor

[0070] 42 Threaded rod or spindle

[0071] 43 Spindle nut

[0072] 50 Tensioned wire

[0073] 60 First Camera Images

[0074] 61 Second camera image

[0075] 62 Images from other cameras

[0076] 70 First plane

[0077] 71 Second Plane

[0078] 80 Computer.

Claims

1. A device for measuring projections on the surface of a rotating body, the rotating body being configured as a cylinder, roller, sleeve or plate for a printing press, the device having a first motor (5) for rotating the rotating body (2) about an axis of rotation (3) and having a measuring device (20), wherein the measuring device (20) comprises for non-contact measurement at least one light source (22) and a plurality of cameras (25), the cameras being arranged substantially in a row (24) oriented parallel to the axis of rotation (3) and having corresponding detection areas (27), characterized in that The measuring device (20) comprises a first scale (32) and a second scale (33), wherein the first scale (32) is arranged on a first side (7) of the rotating body (2) and the second scale (33) is arranged on an opposite second side (8) of the rotating body (2), wherein the first scale (32) is at least partially located in a first detection area (27a) of a first camera (25a) and the second scale (33) is at least partially located in a second detection area (27b) of a second camera (25b).

2. The device according to claim 1, characterized in that The two scales (32, 33) are provided with size scales (32a, 33a).

3. The device according to any one of the preceding claims, characterized in that The two scales (32, 33) are transparent.

4. The device according to any one of the preceding claims, characterized in that The measuring device (20) comprises a first mirror (30) and a second mirror (31).

5. The device according to claim 4, characterized in that The first mirror (30) is arranged behind the first scale (32) relative to the light source (22), so that light (23) from the light source (22) and passing through the first scale (32) is reflected on the first mirror (30) and reaches at least one camera (25).

6. The device according to claim 5, characterized in that The second mirror (31) is arranged behind the second scale (33) relative to the light source (22), so that the light (23) from the light source (22) and passing through the second scale (33) is reflected on the second mirror (31) and reaches at least one camera (25).

7. Device according to one of the preceding claims, characterized in that The light source (22) is movable.

8. The device according to claim 7, characterized in that The camera (25) is movable.

9. The device according to claim 8, characterized in that The light source (22) and the camera (25) are movable together.

10. The device according to any of the preceding claims, characterized in that The light source (22) and the camera (25) are movable in a second plane (71) which is parallel to the first plane (70), and the rotation axis (3) is also located in the first plane (70).

11. A method for measuring a protrusion on the surface of a rotating body, the rotating body being configured as a cylinder, roller, sleeve or plate for a printing press, characterized in that Using a device according to one of the preceding claims and a computer (80); during the measurement, two scales (32, 33) are detected at least partially and two orientation values ​​of the row (24) of cameras (25) are determined in the process for computationally correcting the orientation of the row (24) of cameras (25).

12. The method according to claim 11, characterized in that The two orientation values ​​are determined consecutively.

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