WO2021123043A1

WO2021123043A1 - Sheet detection system and method for providing geometrical structure data of a material sheet and flat bed machine tool

Info

Publication number: WO2021123043A1
Application number: PCT/EP2020/086858
Authority: WO
Inventors: Willi POENITZ; Korbinian WEISS
Original assignee: Trumpf Werkzeugmaschinen Gmbh + Co. Kg
Priority date: 2019-12-18
Filing date: 2020-12-17
Publication date: 2021-06-24
Also published as: DE102019134938A1

Abstract

The invention discloses a sheet detection system (17, 45A, 45B) for a flat bed machine tool (1), which is more particularly designed for cutting sheet metal parts. The sheet detection system (17, 45A, 45B) is designed for detecting geometrical structure data of a material sheet (9) which has been processed or is to be processed. The sheet detection system (17, 45A, 45B) comprises a storage unit with a storage area (51A), which forms a flat storage surface (51) for storing a material sheet (9), more particularly with cut workpieces (59A, 59B). The sheet detection system (17, 45A, 45B) further comprises a camera (15) with an objective lens and a camera sensor (53) for generating a recorded image (57) of the storage area (51A), wherein the objective lens is a shift-lens arrangement which is adjusted for recording the storage area (51A). The recorded image (57) of the storage area (51A) can thereby be presented in a manner compensating for distortion and, more particularly free from distortion.

Description

PANEL DETECTION SYSTEM AND METHOD FOR PROVIDING GE OMETRIC STRUCTURAL DATA OF A MATERIAL PANEL AND FLAT BED TOOL MACHINE

The present invention relates to a sheet detection system for a Flachbettmaschinema machine for detecting geometric structural data of a processed or to be processed material sheet, which is provided, for example, on a pallet changer or is output on a conveyor belt. In particular, the invention relates to a flat bed machine tool with such a board detection system. The invention also relates to a method for providing geometric structural data of a material sheet to be machined or machined with a flat bed machine tool

WO 2018/073419 A1 discloses a sorting assistance system which uses information obtained from recording an arrangement of, for example, cut workpieces, in order to facilitate the sorting process of the various workpieces of the workpiece arrangement. For this purpose, recordings of a workstation at which the arrangement of workpieces is present are recorded with one or more cameras.

One aspect of this disclosure is based on the object of generating image data from raw material stored on a pallet changer or from cut material produced, the image data being provided for evaluation and integration in a digitized monitoring and control of machining processes. In a further aspect, the invention is based on the object of providing image data for digitized support for the separation of workpieces produced with a flat bed machine tool, the image data preferably enabling simple data processing.

At least one of these objects is achieved by a board detection system according to claim 1, a flat bed machine tool according to claim 8 and a method for providing geometric structural data according to claim 10. Further developments are specified in the subclaims.

In one aspect, a sheet detection system for a flat bed machine tool is disclosed, the sheet detection system being designed to record geometric structural data of a sheet of material being machined or to be machined. The flat bed machine tool can in particular be designed for cutting sheet metal parts and comprises: a storage unit with a storage area that forms a flat storage surface for storing a sheet of material, in particular with cut sheet metal parts / workpieces (i.e., for example, an uncut sheet of material or a sheet of material that has been cut / divided into workpieces), and a camera with a lens and a camera sensor that is used for Generation of a recording of the storage area is arranged, wherein the lens is designed as a shift lens, optionally as a tilt-and-shift lens, which is set to accommodate the storage area.

In another aspect, a flatbed machine tool includes a panel sensing system as disclosed herein and a machine tool unit having a housing wall portion. The board detection system comprises a storage unit with a storage area and a camera. The machine tool unit is arranged with the housing wall section on a section of the edge area of the storage area and the camera is arranged on the housing wall section in such a way that a loading and / or removal space is kept free above the storage area as an access area to the storage area.

A further aspect relates to a method for providing geometric structural data of a material sheet to be machined or machined with a flat bed machine tool, which sheet is stored on a storage area of a storage unit. The structural data are optionally provided for the planning, implementation or support of machining processes such as a laser cutting process or part separation. The procedure consists of the following steps:

Recording of the storage area with the material sheet placed on it with a shift lens or optionally a tilt-and-shift lens to generate a recording of the material sheet,

Output of image data of the recording to a control unit of the flatbed machine tool (for performing an image processing algorithm and / or for generating a control signal for a machining process to be performed and / or for generating a sorting signal for a worker and / or for outputting a monitor signal) and

Extraction of geometric structural data in the control unit from the image data of the recording and optionally generation of a control signal for a machining process and / or a sorting signal for a worker. In some embodiments, the camera sensor can extend in an image plane that is parallel to an object plane defined by the support surface. As an alternative or in addition, the camera can be arranged at a distance from the storage surface in an edge area of the storage area. Furthermore, the inclusion of the storage area can represent the storage area in a distortion-compensating manner, and in particular without distortion.

In some embodiments, the shift objective can comprise an objective lens which is shifted in an objective plane from a position at the level of an optical axis of the camera sensor in the direction of a support surface center of the support surface.

In some embodiments, the shift lens can also be designed as a tilt-and-shift lens arrangement, the focal plane of which runs essentially along the storage area. Optionally, the storage area can be recorded with a sharpness that is comparable along the storage surface.

In some embodiments, the camera can be arranged in such a way that a space above the storage surface is kept free as an access space to the storage surface. Optionally, the camera can be arranged on a housing section of a structure adjoining the mounting surface, in particular on a holder or on a housing wall section.

In some embodiments, the objective can comprise an objective lens and a displacement of the objective lens from a position at the level of an optical axis of the camera sensor can be such that a distortion caused by a perspective-related variation in the object resolution is compensated. Optionally, the camera sensor can be a pixel-based digital detector and a pixel-to-millimeter ratio can be uniform in the area of the storage area (in particular, it can be essentially constant in the area of the storage area).

In some embodiments, the storage unit can be designed as a pallet changer, the storage surface being formed by the support surface of a pallet of the pallet changer. Alternatively, the storage unit can be designed as a sorting table, with the storage area is formed by a support surface of the sorting table and optionally by a rotating conveyor belt.

In some developments, the flatbed machine tool can furthermore comprise a control unit which processes image data from the recordings of the camera to generate a control signal to the machine tool unit or to generate a sorting signal to a worker. In some embodiments, the flat bed machine tool is a laser flat bed machine for cutting workpieces from a sheet material with a laser beam.

One advantage of the concepts described here is that they offer the possibility for a sorting assistance system (such as, for example, the sorting assistance system of WO 2018/073419 A1 mentioned above) to reduce the number of cameras required for capturing image data. Correspondingly, the function and the structural design of such a sorting assistance system can be simplified, whereby in particular development capacity, product maintenance and further development can experience advantages. Furthermore, the image quality can improve, so that the detection accuracy and quality increases when the workpiece is removed. Furthermore, a merging of several camera images can be omitted if a single camera additionally allows the detection of a rear pallet area. Accordingly, fewer hardware components are used that could fail during operation.

Concepts are disclosed herein that allow aspects from the prior art to be improved at least in part. In particular, further features and their usefulness emerge from the following description of embodiments with reference to the figures. The figures show:

1A shows a schematic three-dimensional representation of a pallet system, the pallet being loaded with a sheet of material and being available for entry into a laser flat-bed machine or being output (cut) from it,

1B shows a schematic three-dimensional representation of an exemplary removal station of a flat-bed machine tool to illustrate a process of sorting cut workpieces, FIG. 2A shows a schematic representation of a view of a pallet from FIG. 1 with two sheets of material lying on top,

2B shows a schematic representation of an essentially distortion-free recording of the pallet of FIG. 1 with the material sheets from FIG. 2A and a checkerboard pattern plate for lens adjustment and FIGS. 3A-3C are sketches to illustrate the generation of a distortion-free and Optionally, the focus is adjusted recording of a palette with a shift lens or a tilt-and-shift lens.

Aspects described here are based in part on the knowledge that a camera in flatbed machine tools can be directed obliquely at a sheet of material or a workpiece arrangement due to space requirements or due to the fastening options. With conventional lenses, the planes of a camera sensor and the material sheet or workpiece arrangement are aligned with one another at an angle in the range of 30 ° to 70 °. To correct perspective effects in such a recording situation, if a digital camera is used, a directory correction by digital post-processing can be carried out.

In the embodiments of a camera system described herein, too, the camera can be attached to the machine housing, in particular to a machine wall section, as in WO 2018/073419 A1 mentioned at the beginning, and can preferably capture the entire area of the surface of a pallet changer. The camera of the camera system (the recording direction assigned to the camera of the camera system) points diagonally from above onto the pallet changer.

As a result of the use of a shift lens proposed here, the flat camera sensor is not arranged obliquely with respect to the plane to be recorded, but can, for example, extend parallel to this plane to be recorded. Together with z. B. an offset arrangement (shift) of the objective lens makes it possible to capture the pallet with the material plates / workpieces lying on it with as little distortion as possible.

As described in WO 2018/073419 A1 mentioned at the beginning, cameras can be used in the separation of parts on a pallet changer of laser flatbed machines in order to optically detect workpieces (cut material) and follow the operator an image analysis to display information on captured geometric structural data for quick and easier sorting. The inventors have recognized that such a camera-based information acquisition should not take place on a camera arranged directly above the observation plane, since this space can be used for loading the pallet with raw sheets. With a laterally, ie above z. B. the edge of the pallet, provided camera position, the camera detects the pallet from an angle obliquely from above. The inventors have now recognized that with such a positioning of a conventional camera there is a detection accuracy that is significantly lower in the rear area (ie in the area further away from the camera) than in the front area. To avoid such a variation in the detection accuracy, a conventional camera system with a very high resolution can be used, but this is associated with correspondingly high costs. Another possibility is to use several conventional cameras, the recording areas of which cover different areas of the pallet, so that the perspective effect is less, for example. This is also associated with correspondingly high costs

The inventors have now recognized that the use of a shift lens can also solve the problem of detection accuracy optically. With a (pure) shift lens, the lens (generally the lens of the lens) is shifted linearly to the side of the sensor. In this way it can be achieved that the perspective distortion of the pallet is compensated. In the case of a pixel-based digital detector, there is a uniform pixel-to-millimeter ratio over the preferred entire work surface to be recorded. The use of such a shift lens allows the use of significantly cheaper camera sensors with a lower number of pixels, i.e. H. fewer megapixels.

The inventors have also recognized that, in addition to the distortion correction, it is possible to adapt the sharpness plane to the geometry to be recorded. The focal plane should preferably lie “on the sheet”. This can be achieved, for example, with a shift-and-tilt lens approach, which combines shifting (shifting the image plane) and tilting the lens (tilting the image and lens planes) in one lens configuration. The tilting functionality of the lens (preferably under Scheimpflug conditions) is used to form a focal plane that is inclined to the detector planes. In such an optical configura tion of the completely sharply imaged object plane, a larger aperture setting can be used be used. The reduced noise avoids the need for a high ISO sensitivity of the detector and a higher frame rate is possible.

Better image quality can also be achieved by eliminating the need for digital transformation of the image recording. This means that less computing time and CPU performance are required. The lack of digital transformation allows the image-capturing functionality to be implemented in a less complex manner.

In the following, the areas of application of sheet detection systems in 2D flatbed machine tools are explained, on the one hand using the example of a pallet system (FIG.

1 A) and on the other hand using the example of a parts removal station, also referred to herein as Absortierar workstation (Fig. 1B). The resulting difference in the image recording is then explained with reference to FIGS. 2A and 2B. FIGS. 3A to 3C explain the optical concepts in schematic cross sections of a shift lens and a tilt-and-shift lens.

1A shows schematically a laser flat bed machine 1 with a sheet cutting unit 3, which represents the machine area in which a cutting process is carried out. As part of the cutting process, geometric structural data can be obtained and processed in order to support the manufacturing process with the laser flatbed machine 1.

One recognizes an upstream pallet changer 5, which makes it possible to provide the laser flatbed machine 1 with a pallet and, in particular, to operate the laser flatbed machine 1 alternately with several pallets. For example, the pallet changer 5 shows a pallet 7 in a pallet position 5 A. The pallet 7 provides a flat storage surface for storing a sheet of material 9. The material sheet 9 is, for example, a flat material such as a sheet metal. The pallet 7 forms the storage surface with a plurality of support webs 11. For example, it comprises a z. B. rectangular pallet frame with parallel short and parallel long side sections. As shown schematically in FIG. 1A, the support webs 11 can be attached to the pallet frame on the long side sections and accordingly run parallel to the short side sections. The Auflageste ge 11 form, for example, jagged courses of the upper edges. The material sheet 9 to be cut and the cut sheets lie on the tips (support points) formed in this way Workpieces. The support points of the support webs 11 define the plane in which the storage surface extends.

The sheet of material 9 can be moved into the sheet cutting unit 3 with the pallet 7 for a cutting process. Fig. 1A shows a pallet insertion direction 6 by an arrow. For the cutting process, a laser cutting head can be moved in the sheet cutting unit 3 in such a way that a laser beam emerging from the laser cutting head is guided along a desired cutting contour. The movement of the laser cutting head is controlled by a control unit 13. The cutting contours are available in the control unit 13 in the form of a digital machining plan. In this the geometries of the workpieces to be cut, i. This means, in particular, the (outer and inner) contours of the workpieces to be cut, in the form of workpiece geometry data (e.g. circumferential lines) in a cutting plan, in particular in relation to a specified target position of a material table, deposited.

After completion of the cutting process, the pallet 7 is moved out of the sheet cutting unit 3 this time counter to the pallet insertion direction 6 and made available to a sorter for sorting out the cut material. The clippings include z. B. differently shaped Blechtei le (also referred to herein as workpieces). Usually, after the cutting process, the cut workpieces lie as cut material in the form of the original flat material on the pallet 7 and are (still) arranged as a processed sheet of material in a corresponding plate-like manner to one another. The workpieces are from a so-called scrap skeleton, i.e. i.e., the material of the panel that could not be used for workpieces. The workpieces can still be connected to the scrap skeleton via microjoints in order to e.g. B. to prevent the workpieces from tilting during transport on the pallet 7.

Both the position of the material sheet 9 on the pallet 7 and the positions of the cut workpieces in the area of the material sheet 9 after the cutting process represent geometric structural data. These structural data include in particular a course of circumferential lines of the material sheet 9 and / or the cut workpieces in relation to a coordinate system of the pallet 7 or generally the laser flatbed machine 1. The structural data of the material sheet 9 and the structural data of the workpieces can be evaluated and used on the one hand to carry out the cutting process with the laser flatbed machine 1 and also for the further processing of the cut workpieces. A camera 15 is attached to the panel cutting unit 3 in order to acquire the structural data. The camera 15 is part of a board detection system 17 which additionally comprises a storage unit (in FIG. 1A the pallet changer 5), the storage unit forming a storage area which forms a flat storage surface for storing a material sheet. The table detection system 17 is used in accordance with the concepts disclosed herein for obtaining geometric structural data with as little distortion as possible. For this purpose, the camera 15 has, for example, a shift lens or a tilt-and-shift lens.

As shown in Fig. 1A, the camera 15 is attached in a central position with respect to the pallet changer 5, for example, on a housing wall (a housing section) of the panel cutting unit 3, the panel cutting unit 3 in particular forming a structure adjacent to the storage area. As a result, the camera 15 is arranged in such a way that a space above the storage area (i.e. the loading and / or removal space above the storage area) is kept free as an access area to the storage area. The camera 15 enables imaging of the storage area of the pallet 7, which is in the pallet position 5 A, and thus enables a recording of the storage area of the pallet 7 to be generated. A lens opening 15 '(shown in dashed lines) can be seen schematically on the underside of the camera 15. The camera 15 is connected to the control unit 13 of the flat-bed laser machine 1 and transmits the image data of the recordings to it. Image processing of the image data with regard to the geometry of the material sheet 9 and / or the cut material can be carried out in the control unit 13. In particular, geometric structural data can be extracted from the image data of the recording in the control unit.

Further application locations for the concept of a board detection system presented here are processing positions in metal flat-bed machines. Thus, FIG. 1B shows an illustration of an exemplary sorting workstation of a production system 21. The production system 21 comprises a flat-bed machine tool 23 for producing workpieces. The flat bed machine tool 23 can also be designed as a laser flat bed machine or alternatively, for example, as a punching machine.

The manufacturing system 21 further comprises a conveyor device 25. In the manufacturing system 21, the cut material was transferred to the conveyor device 25 by machine or manually and with this further processing steps (for example a part separation) is supplied. When transported to the next processing step, the cut material retains the plate-shaped arrangement as far as possible.

In Fig. 1B, the conveyor device 25 is shown schematically as a conveyor belt system. It comprises a revolving conveyor belt 25A on which workpieces 27A, 27B, 27C cut as clippings are indicated in scrap grids 29. The workpieces 27A, 27B, 27C are still in a plate-shaped arrangement and are transported to a sorting location 31. Usually a light barrier ensures that the workpieces 27A, 27B, 27C are not guided over the turning point of the circulating conveyor belt 25A. In addition, the drive to the conveyor belt 25A can be controlled manually by a worker 33 via a switch 35.

The front workpieces 27A of the plate-shaped arrangement are within reach of the Wer kers 33, so that he has access to a limited number of workpieces at the sorting point 31, here the workpieces 27A of the first row. The worker 33 can grasp these workpieces 27A and sort storage locations A, B, C, D, which are provided, for example, on a storage area of a transport carriage 37 and belong to corresponding orders and / or subsequent processing steps. Correspondingly, the worker 33 picks up the workpieces 27A from the conveyor belt 25A, removes any microjoints and assigns the workpieces 27A to the respective orders by placing them on the storage locations A, B, C, D.

According to the concepts disclosed herein, the sorting process can be used to facilitate correct sorting by displaying e.g. B. workpiece representations and job information on z. B. a monitor 39 are supported. For example, workpiece representations 41A and, optionally, order information 41B can be digitally stored in control unit 13 for this purpose. For this purpose, the monitor 39 is activated by the control unit 13 via a signal line Sm. For example, in the arrangement of FIG. 1B, the monitor 39 is positioned above the conveyor belt 25A. It preferably extends across the width of the conveyor belt 25A. Via the signal line Sm, sorting signals, which were obtained from the image data of the recordings of the camera in the control unit, can be given to the worker 33, which are displayed on the monitor. Alternative sorting signals can e.g. B. be output acoustically. Alternatively or additionally, control signal Sw for a machining process can be output to the machine tool unit, for example for aligning the cutting contours of the machining plan with the recorded position of the material sheet 9.

In order to be able to display corresponding information to the worker 33, it is necessary that the control unit 13 can correctly output information about the work pieces that have just been supplied to the worker 33. For this purpose, a camera 15 can be provided above the circulating conveyor belt 25A in order to digitally record the arrangement of output workpieces. The camera 15 comprises, for example, a shift lens or a tilt and shift lens.

In Fig. 1B it is indicated that the camera 15 outputs image information to the control unit 13 via a signal line Sk, which can be evaluated by the control unit 13 with image processing algorithms. In FIG. 1B, the monitor 39 schematically shows the front row of workpieces 27A in the form of workpiece image data (workpiece representations 41A) stored in the control unit 13. In addition to the illustrated workpiece image data of the workpieces 27A, order information 41B belonging to the respective workpieces, for. B. be shown above each of the workpiece representations.

Fig. 2A shows a view 43 of a storage surface of a pallet 7 ‘a pallet changer 5‘ at an angle of view obliquely from above, as it is, for. B. for the camera 15 of FIG. 1A with regard to the recording direction on the pallet changer 5. In the storage area of the pallet 7 ‘, two material panels 9A, 9B have been placed. Fig. 1A illustrates the perspective of the view based on converging circumferential lines of the material sheets 9A, 9B and the pallet 7 'on which the material sheets 9A, 9B lie. Likewise, the parallel long side sections of the pallet frame run towards one another. A camera with a conventional lens would produce a recording with corresponding, perspective-recorded For men by the conventional lens, the shapes of the material sheets according to Fig.

1 A is mapped onto the camera sensor. For an image with reduced distortion, image processing algorithms then have to calculate the perspective distortions from the image data or take them into account in further image processing on the basis of corresponding scaling / calibration. FIG. 2B shows a camera recording 45 of the storage surface shown in FIG. 2A, as it can be produced according to the invention, for example, with a shift lens or a tilt-and-shift lens. The shift lens or the tilt-and-shift lens are set in such a way that a distortion-compensating image of the support surface on the camera sensor results, so that the true shapes (rectangular shape) of the material sheets 9A,

9B and the pallet 7 ‘in the receptacle 45 can be seen. In addition, the sharpness of the image can be adjusted uniformly along the support surface with a tilt-shift lens.

It is obvious that the receptacle 45 shown in FIG. 2B simplifies the image processing, so that it is easier to obtain geometric structural data from sheets of material and / or from cut material.

The distortion-compensating imaging with a shift lens or a tilt-and-shift lens is preferably distortion-free; d. This means that the geometry of an imaged material plate or a plate-shaped workpiece in the plane of the camera sensor corresponds to the real geometry in the storage area.

In FIG. 2B, in addition to the right corners reproducing the material sheets 9A, 9B, a distortion-free mapped checkerboard pattern 46 can be seen, as can be used, for example, to calibrate a camera with a shift lens or a tilt-and-shift lens. The checkerboard pattern 46 again shows the uniform pixel-to-millimeter ratio in the area of the depicted storage area.

In the context of this disclosure, distortion-compensating and distortion-free refers in particular to the comparison with a perspective-related distortion of a recording with a conventional camera lens. Such (perspective) directories are caused in particular by the increasing distance between objects / imaged areas and the camera.

The varying distance also influences the sharpness of pictures taken with conventional lenses. Although a comparable depth of field can at least partially be achieved via the aperture setting, the scope of the depth of field is in particular in the geometric arrangements of a camera arranged on the edge with respect to a pallet unsatisfactory. In contrast to this, a shift lens and, in particular, a tilt-and-shift lens enable the storage area to be recorded with a sharpness that is comparable along the support surface.

FIGS. 3A and 3B illustrate schematically configurations of board detection systems 45A, 45B, their camera systems 47, 49 with a shift lens arrangement (FIG. 3A) or a tilt-and-shift lens arrangement (FIG. 3B ) capture a storage area 51. During the operation of a flat bed machine tool in which the sheet detection systems are used, essentially two-dimensional sheets of material for machining or machined (plate-shaped) objects lie on the storage surface 51. The lens arrangements each image the storage area 51 on a camera sensor 53, which generates a corresponding digital recording (see FIG. 3C) of the recorded storage area of the storage area 51.

Geometric structural data can then be obtained from the digital recording, for example the course of a circumferential line of a sheet of material or of a workpiece in the storage area. The circumference can, for. B. can be derived from a contour profile around an area of uniform image information when an imaged plate-shaped mate rial is characterized by a uniform surface.

The schematic sectional views through the camera systems 47, 49 shown in FIGS. 3A and 3B each show the camera sensor 53, which defines an image plane 53A, and a lens 55, which represents a schematic lens and between the camera sensor 53 and the lens opening 15 'is arranged. The lens 55 is assigned an objective plane 55A. The bearing surface 51 represents an object plane 51A. In the sectional views of FIGS. 3A and 3B, the positions and orientations of the object plane 51A, image plane 53A and objective plane 55A can be seen.

To illustrate the optical effect of the lens arrangements, FIG. 3C shows an essentially distortion-free receptacle 57 of a storage area 51A. The receptacle 57 shows a plurality of plate-shaped workpieces 59A, 59B cut from a sheet of material. The receptacle 57 can be generated with the table detection stars 45A, 45B, wherein the image sharpness can vary along the pallet insertion direction 6. This is illustrated by the circumferential lines of the workpieces 59B shown in dashed lines, for example at a pure shift lens arrangement (FIG. 3A) cannot be imaged as sharply as the workpieces 59A.

To explain a shift lens arrangement in a flat bed machine tool for cutting sheet metal parts, FIG. 3A schematically shows a section along the pallet insertion direction 6 of a pallet system of the flat bed machine tool (see FIG. 1A). As in FIG. 1A, the camera system 47 is attached to the panel cutting unit 3 above the storage surface 51. In particular, the camera system 47 is at a distance from the storage area, namely above an edge area of the storage area of the storage area 51 is arranged.

The lens arrangement is designed in such a way that the entire storage surface 51, but at least the storage area on a pallet, can be imaged on the camera sensor 53 (imaging lines 60). The camera sensor 53 extends in one plane and thus defines the image plane 53 A. The image plane 53 A extends parallel to the object plane 51 A and to the objective plane 55A.

3A further shows an optical axis 63 extending orthogonally to the image plane 53A and through the center of the camera sensor 53, an optical axis 65 extending orthogonally to the lens plane 55A and through the center of the lens 55 and an optical axis 65 orthogonally to the object plane 51A and through a center point 61 A of the bearing surface 51 running optical axis 61.

In a conventional camera, the optical axis 63 and the optical axis 65 coincide and are usually aligned with the center point 61 A of the bearing surface 51 (generally my on the desired image center point).

In the shift objective arrangement of FIG. 3A, the optical axis 63 and the optical axis 65 are now shifted along the pallet insertion direction 6. That is, the objective lens 55 is shifted in the objective plane 55A from a position at the level of the optical axis 63 of the camera sensor 53 in the direction of the center of the bearing surface (center point 61A of the bearing surface 51) of the bearing surface. This shift (Shift S) can be set in such a way that the falling lines (converging in the distance) caused by the perspective without shift are rectified (parallelized). The perspective distortion / distortion can thus be compensated for by setting the shift. So Despite the offset arrangement of the camera system 47 with respect to the center point 61A (the optical axis 65 running through the lens opening 15 '), a distortion-compensating mapping of the bearing surface 51 can be implemented on the camera sensor and the space above the bearing surface 51 is kept free of optical components become.

3B schematically shows the section through a tilt-and-shift lens arrangement. The plane of the camera sensor 53 runs at an angle α to the bearing surface 51, so that the image plane 53A is tilted to the object plane 51A. (An angle α of 90 ° is shown as an example.) Furthermore, the lens 55 is tilted at an angle β to the plane of the camera sensor 53. The object plane 51A, the image plane 53A and the objective plane 55A preferably meet the Scheimpflug condition and intersect in a common straight line G, which in FIG. 3C extends perpendicular to the plane of the drawing. If this is the case, the angles α and β can be selected in such a way that, in addition to the distortion-free image, there is also a uniform sharpness along the bearing surface 51 in the image produced. That is, the object plane 51 A is mapped consistently sharp (with a comparable sharpness) onto the image plane 53 A, since the sharpness plane of the tilt-and-shift lens arrangement runs essentially along the support surface (51).

As an alternative to attaching the camera to a housing section of the sheet cutting unit, a separate holder for the camera can be provided, for example for a sorting table (for example free-standing or based on a conveyor belt). The sorting table can be formed, for example, similar to the pallet changer as a shelf for a pallet.

It is explicitly emphasized that all features disclosed in the description and / or the claims are viewed as separate and independent of one another for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, regardless of the combinations of features in the embodiments and / or the claims should be. It is explicitly stated that all range specifications or specifications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a limit of a range specification.

Claims

1. Board detection system (17, 45A, 45B) for a flat bed machine tool (1), which is designed in particular for cutting sheet metal parts, the board detection system (17, 45A, 45B) being designed to detect geometric structural data of a machined or to be machined Material sheet (9), comprising: a storage unit with a storage area (51A) which forms a planar storage area (51) for storing a material sheet (9), in particular with cut workpieces (59A, 59B), and a camera (15) with an objective and a camera sensor (53) for generating a recording (57) of the storage area (51A), the objective being designed as a shift lens arrangement which is set for recording the storage area (51A).

2. panel detection system (17, 45 A, 45B) according to claim 1, wherein the camera sensor (53) extends in an image plane (53 A) which is parallel to an object plane (51A) defined by the bearing surface (51), and / or wherein the camera (15) is arranged at a distance from the storage area (51) in an edge area of the storage area (51A) and / or wherein the receptacle (57) of the storage area (51A) compensates for the storage area (51A), and in particular without distortion.

3. panel detection system (17, 45 A, 45B) according to claim 1 or 2, wherein the shift lens comprises an objective lens (55) in an objective plane (55A) from a position at the level of an optical axis (63) of the camera sensor (53) is moved in the direction of a Lagerungsflä chenmitte (61 A) of the storage surface (51).

4. panel detection system (17, 45 A, 45B) according to any one of the preceding claims, wherein the shift lens is further designed as a tilt-and-shift lens arrangement, the focal plane of which extends substantially along the bearing surface (51), and the storage area (51A) optionally being recorded with a sharpness that is comparable along the storage surface (51).

5. panel detection system (17, 45 A, 45B) according to any one of the preceding claims, wherein the camera (15) is arranged such that a space above the storage surface (51) is kept free as an access space to the storage surface (51), and wherein the The camera (15) is optionally arranged on a housing section of a structure adjoining the bearing surface (51), in particular on a holder or on a housing wall section.

6. panel detection system (17, 45 A, 45B) according to any one of the preceding claims, wherein the objective comprises an objective lens (55) and a displacement (S) of the objective lens (55) from a position at the level of an optical axis (63) of the camera sensor (53) is such that a distortion caused by a perspective-related variation in the object resolution is compensated, and the camera sensor (53) is optionally a pixel-based digital detector and has a pixel-to-millimeter ratio in the range of Storage surface (51) is uniform.

7. panel detection system (17, 45 A, 45B) according to any one of the preceding claims, wherein the storage unit (51) is designed as a pallet changer (5) and the storage surface (51) through the support surface of a pallet (7) of the pallet changer (5 ) is formed, or wherein the storage unit (51) is designed as a sorting table and the storage surface (51) is formed by a support surface of the sorting table and optionally by a rotating conveyor belt (25 A).

8. Flat bed machine tool (1) with: a panel detection system (17, 45A, 45B) according to one of the preceding claims, which comprises a storage unit with a storage area (51A) and a camera (15), and a machine tool unit (3) with a Housing wall section, the machine tool unit (3) with the housing wall section being arranged on a section of an edge region of the storage area (51A) and the camera (15) being arranged on the housing wall section in such a way that a loading and / or removal space above the storage area ( 51) is kept free as an access area to the storage area (51).

9. Flatbed machine tool (1) according to claim 8, further comprising a control unit (13), the image data of the recordings of the camera (15) for generating a control signal (Sw) to the machine tool unit (3) or for generating a sorting signal to a worker (33) processed, and / or wherein the flat bed machine tool (1) is a laser flat bed machine for cutting workpieces (59A, 59B) from a tabular material (9) with a laser beam.

10. A method for providing geometrical structural data of a material sheet (9) to be processed or processed with a flat bed machine tool (1), which sheet is stored on a storage area (51A) of a storage unit (51), the structural data being optional for planning, implementation or support of machining processes such as a laser cutting process or part separation are provided, with the following steps:

Taking up a recording (57) of the storage area (51A) with the material sheet (9) to be processed or processed on it with a shift lens or a tilt and shift lens to generate a recording (57) of the to be processed or processed Material sheet (9),

Output of image data of the recording (57) to a control unit (13) of the flat bed machine tool (1) and

Extraction of geometric structural data in the control unit (13) from the image data of the recording (57) and optionally generation of a control signal (Sw) for a machining process and / or a sorting signal (Sm) for a worker (33).