Laser processing machine and laser processing method

Abstract

A laser processing machine for metal workpieces selected from the group of elongated metal elements to produce cut workpieces, comprising a laser device (4) to direct a laser beam (5) onto the workpiece (2), a movement unit (6) to induce a relative movement between the workpiece (2) and the laser beam (5), a control unit (7) configured to control the laser device (4) and the movement unit (6) to cut the workpiece (2) according to a predetermined cutting pattern, a monitoring device (10) configured to acquire, in use, a plurality of images (11) of at least one portion of the workpiece (2) and an analysis unit (17). The analysis unit (17), for each zone (8), is configured to identify in the at least one image (11) the respective cut shape using in the identification of the respective cut shape the respective shape to be cut according to the cutting pattern. The analysis unit (17) is also configured to determine for each zone (8) in the at least one respective image (11) at least a first point (41) and at least a second point (42) of the identified cut shape and measures a measured distance (d) between the first point (41) and the second point (42).

Description

[0001] LASER PROCESSING MACHINE AND LASER PROCESSING METHOD

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No . 102024000021828 filed on October 2 , 2024 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The present invention relates to a laser process ing machine for metal workpieces selected from the group of elongated metal elements . In particular, the present invention relates to a laser proces sing machine which enables automation of the quality control of the cut workpiece , capable of detecting dimensional measurements of cut geometries .

[0006] The present invention also relates to a method for the laser processing of metal workpieces selected from the group of elongated metal elements . In particular, the present invention relates to a method for the laser processing of elongated metal elements which enables an automation of the quality control of the cut workpiece capable of detecting dimensional measurements of cut geometries .

[0007] Background

[0008] Machines for the laser processing of metal workpieces to produce cut workpieces are well known . For example , a typical laser processing machine comprises a laser device adapted to direct a laser beam onto the workpiece , a movement unit for inducing a relative movement between the laser beam and the workpiece , and a control unit configured to control the laser device and the movement unit to cut the workpiece according to a predetermined cutting pattern . By workpiece is meant any flat or deformed planar element , tubular or more generally elongated ( thus also including L- , C- , U- , H- , I-shaped beams , etc . ) , on which laser processing operations , which also include cutting, are to be carried out , in order to obtain a cut workpiece .

[0009] The predetermined cutting pattern associates a respective shape to be cut with each of a plurality of zones of the workpiece , to obtain a cut workpiece having a plurality of zones , each provided with a respective cut shape . In other words , the predetermined cutting pattern defines the desired cut workpiece .

[0010] Furthermore , each shape to be cut is expressed in terms of a cutting profile and / or in a speci fic shape of a portion of the workpiece devoid of material .

[0011] In use , the laser beam removes material from the workpiece according to the respective shapes to be cut as defined in the respective predetermined cutting pattern . For example , not all parts are to be removed by the laser beam but only those parts which then, after the closing of the cut geometry, cause the detachment of a respective scrap piece , meaning by scrap piece the metal part contained within a completely cut closed geometry : for example a circular geometry results in a scrap piece of material of circular shape , or a geometry that traces a complete section of a tube results in a scrap piece having the shape of the section of the tube itsel f .

[0012] At the end of a laser cut along a closed geometry, the corresponding scrap piece detaches and falls .

[0013] Laser processing machines and the respective laser processing methods provide very satis factory results . However, in the sector, the need is felt for a further improvement of laser processing machines and / or laser processing methods , in particular to veri fy that the cutting process is carried out in the desired manner, more speci fically by respecting geometric parameters that guarantee an adequate quality of the result by means of automations capable of detecting dimensional measurements .

[0014] Summary

[0015] The obj ect of the present invention is to provide an improved laser processing machine , in particular a laser processing machine which enables automation of the quality control of the cut workpiece .

[0016] More particularly, it relates to a laser processing machine capable of detecting dimensional measurements of cut geometries .

[0017] Furthermore , the obj ect of the present invention is to provide an improved laser cutting method, in particular a method which enables an automation of the quality control of the cut workpiece .

[0018] More particularly, it relates to a method capable of detecting dimensional measurements of cut geometries .

[0019] The aforesaid obj ects are achieved by the present invention, as it relates to a laser processing machine and a laser cutting method as defined in the respective independent claims . Alternative preferred embodiments are protected in the respective dependent claims .

[0020] Brief Description of the Drawings

[0021] For a better understanding of the present invention, a preferred embodiment is described below, by way of nonlimiting example and with reference to the accompanying drawings , in which : - Figure 1 schematically and partially illustrates a laser processing machine according to the present invention;

[0022] - Figures 2a, 3a, 4a and 5a schematically illustrate respective images captured by a monitoring device of the laser processing machine of Figure 1 during a laser cutting process ; and

[0023] - Figures 2b, 3b, 4b and 5b schematically illustrate respective processings of the images of Figures 2a, 3a, 4a and 5a ;

[0024] - Figures 6a and 6b schematically illustrate examples of assessments performed by an analysis unit of the laser processing machine ; and

[0025] Figures 7a and 7b schematically illustrate the operation of a neural network trained for image processing .

[0026] Description of Embodiments

[0027] In Figure 1 , 1 generally indicates , as a whole , a laser processing machine configured to perform laser cutting of a metal workpiece 2 to obtain a cut workpiece .

[0028] By workpiece is meant any planar, deformed, tubular or more generally elongated element ( thus also including L- , C- , U- , H- , I-shaped beams , etc . ) , on which laser processing operations , which also include laser cutting, are to be carried out , in order to obtain a cut workpiece .

[0029] More speci fically, workpiece 2 may be selected from the group of a planar element ( also deformed) , for example a planar sheet or a deformed sheet , or an elongated element , for example a tube or a bar .

[0030] Advantageously, workpiece 2 may be made of and / or comprise a metallic material .

[0031] Preferably, workpiece 2 is selected from the group of metal sheets and elongated metal elements , such as tubes or bars .

[0032] In particular, laser processing machine 1 can be configured to perform laser cutting, in particular of portions of workpiece 2 with thicknesses less than about 20 mm for tubular elements and about 60 mm for planar sheets .

[0033] In greater detail , laser processing machine 1 comprises :

[0034] - a laser device 4 configured to direct a laser beam 5 onto workpiece 2 ;

[0035] - a movement unit 6 for inducing a relative movement between workpiece 2 and laser beam 5 ; and

[0036] - a control unit 7 configured to control the operation of laser processing machine 1 itsel f .

[0037] In greater detail , control unit 7 may be configured to control laser device 4 and movement unit 6 to cut workpiece 2 according to a predetermined cutting pattern .

[0038] In greater detai l , the predetermined cutting pattern may associate a respective shape to be cut with each of a plurality of zones 8 of workpiece 2 , and in particular to obtain a cut workpiece having a plurality of zones 8 , each provided with a respective cut shape .

[0039] In other words , the predetermined cutting pattern describes how the plurality of zones 8 of workpiece 2 are to be cut to obtain the desired cut workpiece .

[0040] In greater detail , each shape to be cut defines a cutting profile 40 ( that is , a cutting outline ) . In particular, laser device 4 may be configured to cut each zone 8 along the respective cutting profile 40 by means of laser beam 5 .

[0041] In particular, each cutting profile 40 defines the part of the respective zone 8 that is to be removed by laser beam In further detail , each shape to be cut also defines a speci fic shape of a portion of workpiece 2 devoid of material , for example a hole .

[0042] In particular, each portion devoid of material is delimited by the respective cutting profile 40 .

[0043] In further detail , cutting profile 40 delimits the part of the respective zone 8 that is removed during the performance of the laser cut , which in turn can define a portion of workpiece 2 that is detached from the rest of workpiece 2 . This portion is a scrap piece of the respective zone 8 that must separate from the rest of workpiece 2 , thus leaving the respective portion devoid of material .

[0044] Following the performance of the laser cut o f a respective zone 8 , in the event of a correct performance , a cut shape is present , characterized by the respective cutting profile 40 and the presence of the respective portion devoid of material ( that is , the scrap piece is not present in the portion devoid of material ) .

[0045] Furthermore , control unit 7 may be configured to control laser device 4 so that laser beam 5 , in use , cuts workpiece 2 at the respective zone 8 according to cutting profile 40 . Following the execution of the laser cut at the respective zone 8 , a scrap piece is present which, in the case of a correct cut , should detach from the rest of workpiece 2 and should leave the portion devoid of material free .

[0046] For example , a shape to be cut could be a rectangular area, a circular area, an area of generic shape or a heading cut that defines the beginning and the end of the workpiece ( see also Figures 2a, 3a, 4a and 5a ) . Obviously, the shapes can also be more complex . In the case of a rectangular area, the respective cutting profile 40 is defined by two pairs of parallel lines perpendicular to each other . After the performance of the laser cut , at the respective zone 8 , a rectangular scrap piece detaches , leaving free a rectangularly shaped portion devoid of material .

[0047] Possibly, the predetermined cutting pattern may be saved in control unit 7 in the form of a two-dimensional and / or three-dimensional drawing . For example , the two- dimensional and / or three-dimensional drawing may represent the desired cut workpiece , which is nothing other than an overlay of workpiece 2 and the zones 8 with the respective shapes to be cut .

[0048] More speci fically, the two-dimensional and / or three- dimensional drawing may be based on software for Computer- Aided Design, CAD and / or software for Computer-Aided Manufacturing, CAM .

[0049] Control unit 7 may comprise a memory .

[0050] Preferably but not necessarily, the memory may be configured to store one or more cutting patterns , in particular each associated with a respective type of workpiece 2 . Furthermore , the memory may also comprise the respective shapes to be cut defined in each cutting pattern .

[0051] In greater detail , laser device 4 may comprise an emission source for laser beam 5 operatively connected to control unit 7 and configured to emit laser beam 5 .

[0052] Furthermore , laser device 4 may comprise an optical assembly configured to define the optical path of laser beam 5 .

[0053] Advantageously, the optical assembly may be arranged in a housing 9 of laser device 4 .

[0054] Movement unit 6 may be configured to move the housing 9 and / or components of the optical assembly, to move laser beam 5 relative to workpiece 2 .

[0055] Alternatively or in addition, movement unit 6 may be configured to modi fy, in use , a respective position of workpiece 2 relative to a reference point and / or to angularly move workpiece 2 around an axis of rotation A.

[0056] In particular, the movement relative to the reference point may be a movement along a linear axis or the movement may be described by linear movements , each along a respective axis di f ferent from the others . That is , the movement relative to the reference point is a movement in Cartesian space and the reference point may be defined as the zero point .

[0057] More speci fically, control unit 7 may be configured to control movement unit 6 so as to coordinate the movement of laser beam 5 and / or of workpiece 2 to perform the laser cutting according to the cutting pattern; for example , control unit 7 controls laser beam 5 and workpiece 2 by means of movement unit 6 to cut the respective cutting profiles which then determine the cut shapes .

[0058] Preferably, laser processing machine 1 may also comprise : a pressurised gas generation device , for example nitrogen, oxygen or compressed air, operatively connected to control unit 7 and configured to direct a j et of gas onto the cutting zone in order to remove from workpiece 2 the material melted by the laser cutting process .

[0059] Laser processing machine 1 may also comprise a suction unit configured to remove fumes and / or auxiliary products of the laser cutting and / or small-si zed scrap pieces .

[0060] Control unit 7 may also be configured to control process parameters of laser processing machine 1 , for example an intensity of laser beam 5 and / or a frequency and / or a duty cycle of the pulsed mode of laser beam 5 and / or a focal position of laser beam 5 and / or a diameter of laser beam 5 and / or a determined speed of the relative movement between laser beam 5 and workpiece 2 and / or the gas j et and / or a gas pressure of the gas j et and / or a position of a noz zle configured to emit a gas j et .

[0061] With particular reference to Figure 1 , laser processing machine 1 also comprises a monitoring device 10 configured to acquire a plurality of images 11 of at least one portion of workpiece 2 during the performance of the laser cutting .

[0062] In particular, monitoring device 10 may be configured to acquire a sequence of images 11 in which each image 11 corresponds to a di f ferent moment in time with respect to the other images .

[0063] In the illustrated, non-binding example , during the performance of the laser cutting, monitoring device 10 is fixed in space .

[0064] In view of the movement of workpiece 2 relative to the reference point and / or the angular movement of workpiece 2 , it is to be noted that during the acquisition of images 11 , the relative position of workpiece 2 in images 11 also changes .

[0065] Alternatively, monitoring device 10 may be mobi le in space , and in particular may move during the performance of the laser cutting . For example , monitoring device 10 may be integral with the housing 9 .

[0066] In greater detail , monitoring device 10 may comprise an image acquisition device 15 , for example a camera, a photo camera or a video camera, for example of the CCD or CMOS type , configured to acquire images 11 .

[0067] More speci fically, acquisition device 15 may be configured to continuously acquire images 11 , so as to obtain a time sequence of images 11 .

[0068] Monitoring device 10 may also comprise more than one acquisition device 15 suitably spaced from each other .

[0069] Preferably but not necessarily, monitoring device 10 may also comprise a light source 16 configured to illuminate workpiece 2 .

[0070] In particular, l ight source 16 may be configured to emit light in a wavelength range that does not include the process light , such as blue illumination light in the case where the process laser has a wavelength in the infrared range , to reduce the disturbance introduced by the process light .

[0071] Furthermore , light source 16 may also comprise a filter .

[0072] Furthermore , light source 16 may be positioned to avoid the formation of unwanted shadows on the portion of workpiece 2 .

[0073] Laser processing machine 1 may also comprise a protective housing 18 defining a workspace in which workpiece 2 is cut . In particular, the protective housing is configured to ensure that during the cutting process the laser radiation cannot escape from the protective housing 18 .

[0074] Preferably but not necessarily, monitoring device 10 , more speci fically acquisition device 15 , and even more speci fically light source 16 , may be arranged in the workspace .

[0075] Laser processing machine 1 also comprises an analysis unit 17 operatively connected to monitoring device 10 and configured to analyze at least one respective image 11 for each zone 8 .

[0076] In greater detail , for each zone 8 , analysis unit 17 is configured to identi fy the respective cut shape ( s ) in the at least one image 11 .

[0077] Furthermore , for each zone 8 , analysis unit 17 is configured to identi fy the respective cut shape using the respective shape to be cut according to the cutting pattern .

[0078] In particular, the cutting pattern defines an ideal relative positioning of each cut shape on workpiece 2 , and in particular also the geometry of the cut shape to be expected .

[0079] In addition, the cutting pattern defines what analysis unit 17 should expect as a cut shape both in terms of geometry and in terms of ideal relative positioning .

[0080] The use of the cutting pattern in identi fying the cut shape enables , for each zone 8 , faster processing of the respective image 11 .

[0081] With reference to Figures 6a and 6b, analysis unit 17 is also configured to determine for each zone 8 in the at least one respective image 11 at least a first point 41 and at least a second point 42 of the identi fied cut shape . For example , the first point 41 and the second point 42 may be defined by respective points of the respective cutting profile 40 which delimits the respective cut shape .

[0082] Furthermore , analysis unit 17 is also configured to measure a measured distance d between the first point 41 and the second point 42 .

[0083] In particular, each first point 41 and the respective second point 42 may be selected such that the respective distance is a crucial and / or critical distance , that is , the respective distance must have a higher precision compared to other possible distances between other points of the respective cut shape . In other words , each first point 41 and the respective second point 42 are selected so as to determine the respective measured distance which allows for a smaller tolerance compared to distances between other points of the respective cut shape .

[0084] Preferably but not necessarily, each first point 41 and each second point 42 is a respective point of the respective cutting profile 40 .

[0085] Preferably but not necessarily, analysis unit 17 is configured to compare each measured distance d with an expected distance , to determine whether the respective cut shape of the respective zone 8 corresponds to the respective shape to be cut .

[0086] In particular, in the case of a correctly functioning laser cut , each cut shape ( substantially) corresponds to the respective shape to be cut . Therefore , di f ferences ( exceeding a defined tolerance as a function of the expected quality) between the measured distance d and the respective expected distance are indicative o f the fact that the laser cut has not been performed entirely correctly .

[0087] For example , analysis unit 17 may be configured to determine that a cut shape does not correspond to the shape to be cut i f at least one respective measured distance d does not correspond to the respective expected distance .

[0088] In particular, analysis unit 17 may be configured to read each expected distance from the memory ( in which all the expected distances are saved) .

[0089] More speci fically, analysis unit 17 is also configured to determine for each measured distance d that the measured distance d corresponds to the expected distance i f an absolute value of a di f ference between the measured distance d and the expected distance is les s than a threshold value . In other words , analysis unit 17 is configured to consider the possible tolerances between the expected distances and the respective measured distances d .

[0090] Preferably, each threshold value depends on the respective cut shape of the respective zone 8 . In particular, the respective threshold values need not necessarily be equal for the various zones 8 . For example , it is possible that the precision relative to a first zone 8 must be greater than that relative to a second zone 8 . In other words , for some zones 8 the variations between the cut shape and the respective shape to be cut expressed in dif ferences between the respective measured distances d and the respective expected distances may be greater or smaller in comparison with other zones 8 .

[0091] In other words , the tolerances between the cut shape and the respective shape to be cut may vary from zone 8 to zone 8 .

[0092] Preferably but not necessarily, analysis unit 17 is configured to associate a plurality of pairs of a respective first point 41 and a respective second point 42 with each or some cut shapes and to determine the respective measured distance d for each pair .

[0093] In Figures 6a and 6b, a cut shape is indicated which corresponds to a square which is delimited by the respective cutting profile 40 which comprises four straight lines . Each line is delimited by a respective first point 41 and a respective second point 42 . It is noted that according to the example of Figure 6a, each corner defines both a respective first point 41 and a respective second point 42 .

[0094] According to the example illustrated in Figure 6a, each measured distance d corresponds to a measurement of the length of the segment having the respective first point 41 and the respective second point 42 as its end points ; that is , the lengths of the sides which delimit the rectangular cut shape .

[0095] In an alternative , it would also be possible to evaluate only the measured distance d of one side of the respective cutting profile 40 or more than one measured distance d .

[0096] According to the other example of Figure 6b, the measured distance d between a first point 41 and a second point 42 may also be defined by the length of the perimeter which delimits the cut shape by tracing the perimeter from the first point 41 to the second point 42 clockwise or anticlockwise . In the example of Figure 6b, the first point 41 and the second point 42 correspond and are defined at a corner of the rectangle . By tracing the perimeter clockwise , the measured distance d is obtained, which in turn corresponds to the sum of the lengths of the sides of the perimeter .

[0097] According to another variant , it is also possible to define the first point 41 and the respective second point 42 at opposite corners , and the respective measured di stance d corresponds to the diagonal of the cut shape .

[0098] Furthermore , it is possible that for example in the case of a circular cut shape the first point 41 and the second point 42 allow the measurement of the respective diameter .

[0099] Advantageously, monitoring device 10 is calibrated .

[0100] Furthermore , the analysis unit 17 is configured to express each measured distance d in terms of a length .

[0101] More speci fically, analysis unit 17 is configured to express each measured distance d in millimetres or centimetres or micrometres or any other unit of measurement of length .

[0102] Advantageously, monitoring device 10 is configured to acquire images 11 having a first axis B and a second axis C, in particular perpendicular to the first axis B .

[0103] In greater detail , a first extent of each image 11 along the first axis B is of a first number of pixels and a second extent of each image 11 along the second axis C is of a second number of pixels .

[0104] Furthermore , the calibration of monitoring device 10 involves associating with each pixel a respective first length along the first axis B and a respective second length along the second axis C .

[0105] In particular, the maximum length of each image 11 along the first axis B is defined by the sum of the length of each pixel along the f irst axis B and the maximum length of each image 11 along the second axis C is defined by the sum of the length of each pixel along the second axis C .

[0106] Advantageously, analysis unit 17 i s suitably configured and calibrated to determine a number of pixels between each first point 41 and the respective second point 42 and to trans form the number of pixels into a measurement of length .

[0107] Preferably, analysis unit 17 may be configured to use an arti ficial intelligence algorithm, in particular a trained neural network, in combination with an image analysis algorithm to identi fy each first point 41 and the respective second point 42 .

[0108] In further detail , analysis unit 17 is configured to use the trained neural network to identify at least one zone 8 in the respective images 11. Furthermore, analysis unit 17 is configured to use the image analysis algorithm to determine in the respective images 11 at least a first point 41 and at least a second point 42 of the respective identified cut shape of the zone 8 identified by the trained neural network.

[0109] In other words, analysis unit 17 uses the trained neural network to determine zones 8 which also enable the identification of the cut shapes and uses the image analysis algorithm to determine the first points 41 and the second points 42.

[0110] For example, the image analysis algorithm may be selected from the group comprising Sobel filters, edge detection, Hough transform, and the like.

[0111] In greater detail, the trained neural network is a trained neural network of the convolutional type. In particular, the trained neural network may use a YOLO-type model .

[0112] Preferably, the trained neural network may be configured to segment images 11.

[0113] Preferably, the trained neural network is configured to assign a respective assigned class to each object identified in each image 11. In the specific case, the trained neural network is configured to assign a first assigned class, a second assigned class and a third assigned class. In the specific case, the first assigned class corresponds to a surface (presence of material) of workpiece 2 identified in the respective image 11, the second assigned class corresponds to a part devoid of material (i.e. a zone 8; in other words, the trained neural network associates the second assigned class with the zones 8) and the third assigned class corresponds to a background identified in image 11.

[0114] The trained neural network has been trained using a training dataset obtained from laser cutting processes of various types of workpieces 2 (such as of different shape, cross-section, material, dimensions, etc.) .

[0115] During the laser cutting process of such workpieces 2, images were acquired and / or obtained. In such images, labels were applied which correspond to the first assigned class, the second assigned class and the third assigned class.

[0116] The labelled images thus obtained define the training dataset and have also been divided into training images, test images and validation images.

[0117] It is to be noted that movement unit 6 can induce a linear movement and an angular movement of workpiece 2. However, in the examples of Figures 2a, 3a, 4a and 5a, we have chosen for reasons of simplicity to indicate the progress of the laser cutting process along the linear movement only, showing only different linear positions of workpiece 2, also indicating the formation of the cut shapes of the various zones 8.

[0118] Furthermore, we have chosen the example of a workpiece 2 with a rectangular cross-section to make the example more understandable. However, the concepts described in the present application also apply to workpieces 2 with different cross-sections such as circular, rhombic cross-sections, open sections such as H, L, I, T, C beams, flat bars, etc.

[0119] Furthermore, Figures 6a and 6c schematically illustrate the example of a square cut shape. However, the cut shapes may have different shapes such as circular, rectangular, rhombic or more generically defined by any open or closed geometric line , even curvilinear .

[0120] According to some variants , analysis unit 17 may also be configured to analyze a plurality of images 11 for each or some zones 8 .

[0121] It is to be considered that some or all of images 11 may be used for analyzing related to more than one zone 8 .

[0122] Preferably but not necessarily, laser processing machine 1 may comprise a display unit configured to display images 11 and / or workpiece 2 with the indication of the zones 8 for which the respective cut shape corresponds to the respective shape to be cut ( obtaining respective processed images 11 ' ) , and in particular in a di f ferent manner for those whose respective cut shape does not correspond to the respective shape to be cut .

[0123] In Figures 2a, 3a, 4a and 5a, the display of images 11 is schematically shown . The advancement of workpiece 2 , that is , a modi fication of the positioning relative to the reference point , can be seen . In the speci fic example , the advancement is along a translation axis around which the axis of rotation A rotates . For reasons of simplicity, images 11 in which workpiece 2 is oriented in an angular position di f ferent from that visible in the accompanying drawings have been omitted .

[0124] Then, in Figures 2b, 3b, 4b and 5b, processed images 11 ' are illustrated . In particular, in Figures 2b, 3b, 4b and 5b, the zones 8 for which the cut shape corresponds to the shape to be cut are schematically indicated with hatching, and those for which the cut shape does not correspond to the shape to be cut are indicated only in white . In the speci fic case , the information contained in Figures 2b, 3b, 4b and 5b indicates with hatching the zones 8 for which the respective measured distances d correspond to the respective expected distances .

[0125] It can also be seen from Figures 2b, 3b, 4b and 5b that the information i s updated by the analysis unit 17 with the progress of the overall process .

[0126] In use , a laser cutting method for cutting workpiece 2 is performed, in particular by laser processing machine 1 .

[0127] The method comprises the steps of : a ) directing laser beam 5 onto workpiece 2 ; b ) inducing a relative movement between workpiece 2 and laser beam 5 ; c ) controlling, in particular in a coordinated manner, laser beam 5 and the movement of workpiece 2 according to the respective predetermined cutting pattern which associates with each zone 8 the respective shape to be cut , and to obtain the cut workpiece having the zones 8 , each provided with the respective cut shape ; d) acquiring the plurality of images 11 of at least one portion of workpiece 2 ; and e ) analyzing, for each zone 8 , at least one image 11 to identi fy the respective cut shape in the at least one image 11 .

[0128] In particular, the step of analyzing e ) is performed by analysis unit 17 .

[0129] In greater detail , during the step of analyzing e ) , the respective cut shape is identi fied in the at least one image 11 using the respective shape to be cut according to the cutting pattern in the identi fication .

[0130] In particular, the cutting pattern contains the information that defines for each zone 8 the respective shape to be cut and its relative positioning on workpiece 2 . Therefore , during the step of analyzing e ) , it is possible to identi fy the respective cut shape more simply and quickly .

[0131] During the step o f analyzing e ) , at least one respective first point 41 and at least one respective second point 42 of the respective cut shape are determined for each cut shape identi fied in the at least one respective image 11 .

[0132] According to a variant , during the step of analyzing e ) , a plurality o f pairs of a respective first point 41 and a respective second point 42 are identi fied for at least some cut shapes , as for example schematically indicated in Figure 6a for the example of a square as a cut shape .

[0133] During the step of analyzing e ) , the respective measured distance d between each first point 41 and the respective second point 42 is measured .

[0134] Advantageously, during the step of analyzing e ) , each measured distance d is compared with an expected distance to determine whether the respective cut shape of the respective zone 8 corresponds to the respective shape to be cut .

[0135] More speci fically, during the step of analyzing e ) , it is determined that a cut shape does not correspond to the shape to be cut i f at least one respective measured distance d does not correspond to the respective expected distance .

[0136] In further detail , during the step of analyzing e ) , the correspondence between the measured distance d and the expected distance is determined for each measured distance d i f an absolute value of a di f ference between the measured distance d and the expected distance is less than a threshold value defined as a function of the expected quality .

[0137] In greater detail , during the step of directing a ) , laser device 4 directs laser beam 5 onto workpiece 2 .

[0138] Advantageously, during the step of inducing b ) , the respective position of workpiece 2 relative to the reference point is moved, in particular by movement unit 6 , and / or workpiece 2 is rotated around the axis of rotation A and / or laser beam 5 is moved, in particular by movement unit 6 .

[0139] In greater detai l , during the step of controlling c ) , control unit 7 controls , in particular in a coordinated manner, laser device 4 and movement unit 6 to perform the cutting of the zones 8 according to the respective cutting pattern .

[0140] In further detail , during the step of acquiring, images 11 are acquired by means of acquisition device 15 .

[0141] Preferably, during the step of acquiring, light source 16 illuminates workpiece 2 .

[0142] From an examination of the characteristics of laser processing machine 1 and of the method according to the present invention, the advantages that it allows to be obtained are evident .

[0143] In particular, following the performance of the laser cutting process of workpiece 2 , information is already available regarding the success ful cutting or whether inaccuracies may be present in one or more zones 8 . This facilitates the quality control steps of the various cut workpieces .

[0144] In particular, the information relating to the measured distances d is present , which allows a comparison with the expected distances .

[0145] Finally, it is clear that modi fications and variations can be made to laser processing machine 1 and to the method described and illustrated herein without departing from the scope of protection defined by the claims .

Claims

CLAIMS1. A laser processing machine for metal workpieces (2) selected from the group of elongated metal elements to produce cut workpieces, comprising:- a laser device (4) configured to direct a laser beam (5) onto the workpiece (2) ;- a movement unit (6) for inducing a relative movement between the workpiece (2) and the laser beam (5) ;- a control unit (7) configured to control the laser device (4) and the movement unit (6) to cut the workpiece (2) according to a predetermined cutting pattern which associates with each of a plurality of zones (8) of the workpiece (2) a respective shape to be cut, and to obtain a cut workpiece having a plurality of zones (8) , each provided with a respective cut shape;- a monitoring device (10) configured to acquire, in use, a plurality of images (11) of at least one portion of the workpiece (2) ; and- an analysis unit (17) connected to the monitoring device (10) and configured to analyze for each zone (8) at least one image (11) ; wherein the analysis unit (17) , for each zone (8) , is configured to identify in the at least one image (11) the respective cut shape using for the identification of the respective cut shape the respective shape to be cut according to the cutting pattern; wherein the analysis unit (17) is also configured to determine for each zone (8) in the at least one respective image (11) at least a first point (41) and at least a second point (42) of the identified cut shape; wherein the analysis unit (17) is also configured tomeasure a measured distance (d) between the first point (41) and the second point (42) .

2. Laser processing machine (1) according to claim 1, wherein the analysis unit (17) is configured to compare each measured distance (d) with an expected distance to determine whether the respective cut shape of the respective zone (8) corresponds to the respective shape to be cut.

3. Laser processing machine (1) according to claim 2, wherein the analysis unit (17) is configured to determine for each measured distance (d) that the measured distance (d) corresponds to the expected distance if an absolute value of a difference between the measured distance (d) and the expected distance is less than a threshold value.

4. Laser processing machine (1) according to any one of the preceding claims, wherein the analysis unit (17) is configured to associate a plurality of pairs of a respective first point (41) and a respective second point (42) with each or some cut shapes and to determine the respective measured distance (d) for each pair.

5. Laser processing machine (1) according to any one of the preceding claims, wherein the monitoring device (10) is calibrated and the analysis unit (17) is configured to express each measured distance (d) in terms of a length.

6. Laser processing machine (1) according to claim 5, wherein the analysis unit (17) is configured to express each measured distance (d) in millimeters or centimeters or micrometers or any other unit of measurement of length.

7. Laser processing machine (1) according to claim 5 or 6, wherein the monitoring device (10) is configured to acquire images (11) having a first axis and a second axis, in particular perpendicular to the first axis;wherein a first extent of each image (11) along the first axis is of a first number of pixels and a second extent of each image (11) along the second axis is of a second number of pixels; wherein the calibration of the monitoring device (10) involves associating with each pixel a respective first length along the first axis and a respective second length along the second axis.

8. Laser processing machine (1) according to any one of the preceding claims, wherein the analysis unit (17) is configured to determine a number of pixels between each first point (41) and the respective second point (42) and to transform the number of pixels into a measurement of length.

9. The laser processing machine according to any one of the preceding claims, further comprising a memory configured to store the cutting pattern; wherein the analysis unit (17) is configured to read the cutting pattern and the respective shapes to be cut from the memory.

10. Laser processing machine according to any one of the preceding claims, wherein the monitoring device (10) comprises an image acquisition device (15) and a light source (16) .

11. Las er processing machine (1) according to any one of the preceding claims, further comprising a display unit configured to display the workpiece (2) and / or an image of the workpiece (2) with the indication of the zones (8) for which the respective cut shape corresponds to the respective shape to be cut .

12. Las er processing machine (1) according to any one of the preceding claims, wherein each cut shape is delimitedby a respective cutting profile (40) ; wherein each first point (41) and each second point (42) are respective points of the respective cutting profile (40) .

13. Laser processing machine (1) according to any one of the preceding claims, wherein the analysis unit (17) is configured to use a trained neural network to identify in the respective images (11) at least one zone (8) and an image analysis algorithm to determine in the respective images (11) at least a first point (41) and at least a second point (42) of the respective identified cut shape of the zone (8) identified by the trained neural network.

14. A method for the laser processing of metal workpieces (2) selected from the group of elongated metal elements to produce cut workpieces, comprising the steps of:- directing a laser beam (5) onto the workpiece (2) ;- inducing a relative movement between the workpiece (2) and the laser beam (5) ;- controlling in a coordinated manner the laser beam (5) and the movement of the workpiece (2) according to a predetermined cutting pattern which associates with each of a plurality of zones (8) of the workpiece (2) a respective shape to be cut, and to obtain a cut workpiece having a plurality of zones (8) , each provided with a respective cut shape ;- acquiring a plurality of images (11) of at least one portion of the workpiece (2) ; and- analyzing, for each zone (8) , at least one image (11) to identify in the at least one image (11) the respective cut shape using in the identification the respective shape to be cut according to the cutting pattern;wherein during the step of analyzing at least a first point (41) and at least a second point (42) of the cut shape are determined for each cut shape identified in the at least one respective image (11) ; wherein during the step of analyzing, a distance (d) is measured between the first point (41) and the second point (42) .

15. Method according to claim 14, wherein during the step of analyzing each measured distance (d) is compared with an expected distance to determine whether the respective cut shape of the respective zone (8) corresponds to the respective shape to be cut; and / or wherein during the step of analyzing, the correspondence between the measured distance and the expected distance is determined for each measured distance (d) if an absolute value of a difference between the measured distance (d) and the expected distance is less than a threshold value; and / or wherein during the step of analyzing a plurality of pairs of a respective first point (41) and a respective second point (42) is associated with each cut shape and the respective measured distance (d) is determined for each pair.

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