CN111069787B

CN111069787B - Method and processing machine for processing workpieces

Info

Publication number: CN111069787B
Application number: CN201910993011.7A
Authority: CN
Inventors: B·雷加德; M·黑克尔; M·朔贝尔
Original assignee: Trumpf European Ag
Current assignee: Trumpf European Ag
Priority date: 2018-10-19
Filing date: 2019-10-18
Publication date: 2024-04-02
Anticipated expiration: 2039-10-18
Also published as: CN111069787A; DE102018217940A1

Abstract

The invention relates to a method for machining a workpiece (8) by means of a machining beam, comprising: before processing: a) moving the processing head and the workpiece (8) relative to each other along a predefined desired movement path (9 '), b) determining the relative movement between the processing head and the workpiece (8) by means of an optical detector fixedly connected to the processing head when moving along the predefined desired movement path (9'), and c) determining the corrected desired movement path (9) from the determined relative movement, the method further comprising: the workpiece (8) is processed by a movement of the processing head, which directs the processing beam onto the workpiece (8), and the workpiece (8) relative to each other along a corrected due movement path (9). The invention also relates to a corresponding processing machine for processing a workpiece (8). The invention also relates to a further method for machining a workpiece (8) by means of a machining beam, and to a corresponding machining machine.

Description

Method and processing machine for processing workpieces

Technical Field

The invention relates to a method for machining a workpiece by means of a machining beam. The invention also relates to a processing machine, in particular a laser processing machine, for processing a workpiece, the processing machine comprising: a machining head for machining a workpiece, the machining head being configured for directing a machining beam onto the workpiece; a movement device for moving the processing head and the workpiece relative to each other, and an optical detector fixedly connected with the processing head.

Background

In the case of processing, for example, plate-shaped workpieces, in particular sheet metal, by means of a processing beam, in particular in the case of laser cutting by means of a laser beam, component tolerances occur in the workpiece parts cut, which tolerances may be attributed to deviations of the actual movement path produced in the laser cutting from the predefined intended movement path. Such deviations may be generated by dynamic forces during the relative movement between the machining head and the workpiece during machining: in particular, at high processing speeds, vibrations of the gantry system or the robot to which the processing head is attached or vibrations of the workpiece or the workpiece carrier can occur, which vibrations lead to overshoots when cutting along the cutting contour.

DE102006017629A1 describes a method for laser machining on a workpiece along a predetermined machining path, in which method the deviation of the actual position from the desired position, which occurs during the relative movement of the workpiece and the laser machining head, is sensed and a correction value for deflecting the laser beam into the desired position is determined therefrom, and the laser beam is deflected accordingly. In this case, an overshoot can be detected during the relative movement between the workpiece and the laser processing head, and a deflection of the laser beam, which is opposite to the relative movement, can be set.

DE102006049627A1 describes a method and a device for fine positioning of a tool in which a relative movement between the tool and an object to be processed is sensed by means of at least one sensor and the deviation of the actual movement path of the tool or object thus calculated from the intended movement path is counteracted by means of an actuator by means of a tracking tool or object.

In DE102006049627A1, it is also proposed to irradiate the surface of the object with optical radiation in the region of the processing point and to repeatedly sense the optical radiation reflected from the object surface in the region of the processing point by means of a camera in order to obtain temporally successive optical reflection patterns of overlapping surface regions of the object. The transverse relative movement is determined by comparing the reflection patterns successive in time, as described in detail in DE102005022095 A1.

Disclosure of Invention

The object underlying the present invention is to provide a method and a processing machine by means of which the contour accuracy can be increased when processing a workpiece along a desired movement path.

This object is achieved according to a first aspect by a method for machining a workpiece by means of a machining beam, the method comprising: before processing: a) moving the processing head and the workpiece relative to each other along a predefined desired movement path, b) determining the relative movement between the processing head and the workpiece when moving along the desired movement path by means of a detector fixedly connected to the processing head, and c) determining a corrected movement path from the determined relative movement, wherein the method further comprises: the workpiece is processed by directing a processing beam onto the movement of the processing head and the workpiece relative to each other along the corrected due movement trajectory.

In this respect, it is proposed that the track deviations which occur during the machining of the workpiece due to the relative movement between the machining head and the workpiece, which may be attributed to shaft vibrations or the like, are corrected by: before machining, a predefined desired movement path is followed before machining the workpiece and, if necessary, the deviations that occur are corrected. In this way, the adjustment of the relative movement during the machining of the workpiece by means of the actuator, as described for example in DE102006049627A1, can be dispensed with. In this case, too, the predefined desired movement path is typically traversed at the relative speed or feed speed at which the subsequent processing is carried out.

The method can be used, for example, in a planar processing machine, for example, in a 2D laser cutting machine. In such machines, the machining head is typically moved over the workpiece in two dimensions (X/Y directions) and the workpiece remains stationary. In this case, the movement of the processing head and the workpiece relative to one another corresponds to the movement of the processing head along a predefined desired path relative to the stationary workpiece or the machine frame of the processing machine. Instead of performing the cutting process by means of a processing beam, it is possible, for example, to perform a welding process by means of a laser beam.

In one variant, the determination of the relative movement includes: the method comprises the steps of irradiating the workpiece surface with irradiation radiation in the region of the processing head, detecting the irradiation radiation reflected on the workpiece surface in the region of the processing head in a spot-resolved manner, in order to obtain, when moving along a predefined intended movement path, reflection patterns of overlapping surface regions of the workpiece, which are successive in time, and determining the relative movement by comparing the reflection patterns, which are successive in time.

The relative movement or lateral movement of the surface regions can be determined by comparing the reflection patterns successive in time, for example in the manner described in DE102006049627A1 or DE102005022095A1, typically by means of a calculation of a similarity function, see also the paper "Geometriebasierte Prozess ubergachung und-reglung beim Laserstrahlschwei beta en durch koaxiale Beobachtung DEs Schmelzbades mit Fremdbeleuchtung" by the university of the sub-Albah industry 2012 (geometrical process monitoring and adjustment by means of coaxial observation of the weld pool during laser beam welding), pages 67 to 74, which are incorporated by reference into the present application. In order to determine the relative movement or lateral offset, the image portions with the greatest similarity of the reflection patterns of the overlapping surface regions are determined by means of a similarity function. The direction and magnitude of the (instantaneous) feed speed can thus be ascertained at each position along the predefined intended movement path, at which position the surface area has been sensed in a location-resolved manner. The deviation of the actual movement path from the desired movement path can be determined by comparing the feed speed generated when moving along the predetermined desired movement path. The due motion profile can be corrected accordingly in the manner of: the relative motion that counteracts the deviation is calculated into the due motion profile.

Another aspect of the invention relates to a method for machining a workpiece by means of a machining beam, the method comprising: before processing: a) moving the processing head and the workpiece relative to each other along a predetermined desired movement path at a first relative speed and moving the processing head and the workpiece relative to each other along a predetermined desired movement path at a second greater relative speed, b) determining a deviation between the movement along the predetermined desired movement path at the first relative speed and the movement along the predetermined desired movement path at the second relative speed by means of a detector fixedly connected to the processing head, and c) determining a corrected desired movement path from the determined deviation, wherein the method further comprises: the workpiece is processed by directing a processing beam onto the movement of the processing head and the workpiece relative to each other along the corrected due movement trajectory. In step a), the sequence of movements along the predefined intended movement path is arbitrary, i.e. it can be moved first at a first relative speed and then over time at a second relative speed, or vice versa.

In this aspect of the invention, as in the first aspect of the invention, the profile deviation that may be attributed to the shaft vibration or the like when processing the workpiece is corrected by: before machining, the workpiece is passed before being machined and, if necessary, a predefined desired movement path is corrected. However, contrary to the first aspect described above, the predefined due motion profile is travelled twice at different relative speeds: the first relative speed is relatively low, so that the predefined desired movement path is traversed slowly and with high accuracy. The second relative speed corresponds substantially to the desired relative speed at the time of subsequent processing. Depending on the deviation between the movements along the predefined movement path at two different relative speeds, the predefined movement path can be corrected, for example by calculating a correction that counteracts the deviation into the movement path.

In one variant, the determination of the deviation includes: illuminating the workpiece surface with illuminating radiation in a region of the processing head, sensing the illuminating radiation reflected on the workpiece surface in the region of the processing head in a spot-resolved manner so as to obtain a first reflected pattern of an overlapping surface region of the workpiece when moving along a predetermined due motion trajectory at a first relative speed and a second reflected pattern of the overlapping surface region of the workpiece when moving along the predetermined due motion trajectory at a second relative speed, and determining the deviation by comparing the first and second reflected patterns.

The deviation is determined from a comparison of the first and second reflection patterns, wherein the reflection patterns obtained when the user first or second passes through a predefined desired movement path at two different relative speeds are compared with one another. The first reflection pattern which is obtained when moving at a smaller relative speed constitutes a reference or state of charge, and the second reflection pattern which is obtained when moving at a larger relative speed is offset from the first reflection pattern by a lateral offset. Comparing the first and second reflection patterns for determining the deviation or lateral offset may be similar to the procedure described above, i.e. typically by means of calculation of a similarity function, for example in the manner described in DE102006049627A1 or DE102005022095 A1.

In one variant, the surface area is sensed in a radiation-and location-resolved manner through the processing optics of the processing head, in particular through the focusing optics. In this case, the irradiation of the surface region is usually carried out coaxially or only slightly obliquely with respect to the processing beam directed onto the workpiece. Such illumination has proved to be advantageous in that in this illumination mode the illumination radiation reflected from the surface area generates an irregular reflection pattern in the image on the detector, which facilitates a comparison between the images of the surface area sensed in a location-resolved manner. Coaxial observation or sensing of the surface area, for example by means of imaging optics, has also proven advantageous for performing the comparison. In this case, the detector, for example a camera, is typically arranged coaxially with respect to the machining beam or an extension of the beam axis of the machining beam.

In one variant, steps a) and b) are performed at least once more, wherein the corrected due motion trajectory determined in the preceding step c) constitutes the predetermined due motion trajectory for performing steps a) and b) again. In particular, if the corrected due motion profile deviates significantly from the predefined due motion profile, it may be expedient to walk through the motion profile at least once more and to detect a relative motion or deviation between the processing head and the workpiece. For the case where the deviation or residual error between the actual motion profile and the due motion profile is still relatively large, step c) may also be re-performed in order to generate another corrected due motion profile. This process, i.e. the execution of steps a), b) and if appropriate step c), can be carried out several times until the residual error or the actual-to-desired deviation is sufficiently small.

Another aspect of the invention relates to a machine of the type mentioned at the outset, the machine further comprising: a control device which is configured or programmed/configured for moving the processing head and the workpiece relative to one another along a predefined desired movement path prior to processing; an evaluation device which is designed or programmed/configured for determining a relative movement between the processing head and the workpiece by means of the optical probe when the processing head is moved along the desired movement path and for determining a corrected desired movement path from the determined relative movement, wherein the control device is designed for moving the processing head and the workpiece relative to one another along the corrected desired movement path during processing. The processing machine may be, for example, a laser welder or a laser cutter.

In a further embodiment, the optical detector is configured for the spatially resolved detection of the irradiation radiation reflected on the workpiece surface in the region of the processing head in order to obtain, when moving along a predefined intended movement path, the temporally successive reflection patterns of the overlapping surface regions of the workpiece, and the evaluation device is configured for determining the relative movement by comparing the temporally successive reflection patterns. As described above in connection with the first aspect, the respective instantaneous relative movement between the processing head and the workpiece may be locally determined by calculating a similarity function or by finding the image of maximum similarity of the reflection patterns of the overlapping surface areas.

Another aspect of the invention relates to a machine of the type mentioned at the outset, the machine further comprising: a control device which is constructed or programmed/configured for moving the processing head and the workpiece relative to one another at a first relative speed and at a second, greater relative speed along a predetermined desired movement path prior to processing; an evaluation device which is designed or programmed/configured for determining a deviation between a movement along a predefined desired movement path at a first relative speed and a movement at a second relative speed by means of an optical detector and for determining a corrected desired movement path from the determined deviation, wherein the control device is designed for moving the processing head and the workpiece relative to one another along the corrected desired movement path during processing. As shown above in connection with the corresponding method, along the pre-run at a first relative speedThe movement of a given due course of movement is relatively slow, so that overshoot is avoidedTypically, the second relative speed corresponds to the due speed of movement when the workpiece is subsequently processed.

In one embodiment, the optical detector is configured for the site-resolved sensing of the illumination radiation reflected on the workpiece surface in the region of the processing head in order to obtain a first reflection pattern of the overlapping surface region of the workpiece when moving at a first relative speed along a predefined due movement trajectory and a second reflection pattern of the overlapping surface region of the workpiece when moving at a second relative speed along a predefined due movement trajectory; the evaluation device is designed to determine the deviation by comparing the first and the second reflection pattern. In order to determine the deviation in the form of a lateral offset or a differential, a corresponding first reflection pattern of the first surface region is compared with a second reflection pattern of a second surface region of the workpiece, which overlaps the first surface region, which generally corresponds to the same position along the predefined intended movement path. As explained above, the corrected due motion trajectory can be determined in this way and deviations which may be due to shaft vibrations or the like can already be compensated for before machining.

In another embodiment, the processing machine comprises an illumination source for illuminating the surface of the workpiece with illumination radiation that is preferably coaxial with the processing beam. As explained above, it is advantageous for the sensing of the surface area to irradiate the surface area with irradiation radiation. Irradiation coaxial with the processing beam and thus typically passing through the processing optics of the processing head is advantageous, but not mandatory. The irradiation can also take place, for example, by means of an irradiation source mounted on the outside of the processing head, wherein in this case the beam path of the irradiation radiation does not intersect the beam path of the processing beam in the processing head. If necessary, the irradiation source for irradiating the surface can also be omitted, provided that there is sufficient illumination in the surroundings.

In a further embodiment, the processing machine is configured for illuminating the workpiece surface through processing optics of the processing head, in particular focusing optics, and for detecting the surface area in a point-resolved manner. As described above in connection with the method, the irradiation preferably takes place generally coaxially or only slightly obliquely with respect to the processing beam directed onto the workpiece. Coaxial observation of the surface area, for example by means of imaging optics, has also proven advantageous. As explained above, the detector, which may be, for example, a high-resolution camera, is typically also arranged coaxially with respect to the processing beam or with respect to an extension of the beam axis of the processing beam.

Drawings

Further advantages of the invention result from the description and the drawing. The features mentioned above and yet to be further listed can likewise be used singly or in any combination of a plurality. The embodiments shown and described are not to be understood as a final exhaustive enumeration but rather have exemplary character for the description of the invention.

The drawings show:

fig. 1: a laser processing machine for cutting a workpiece,

fig. 2a, b: the laser processing head of the laser processing machine of figure 1 is shown,

fig. 3: a schematic illustration of a workpiece with a predefined desired movement path of the processing head of figures 2a, b,

fig. 4a, b: two views of the reflection pattern of the irradiation radiation, which is captured by the detector and reflected at the two surface areas on the workpiece surface, and

fig. 5a, b: two views similar to fig. 4a, b of a first and a second reflection pattern are obtained when the first and the second reflection pattern are moved over a predefined desired movement path at two different relative speeds.

In the following description of the drawings, the same reference numerals are used for the same or functionally identical components.

Detailed Description

Fig. 1 shows a laser processing machine 1 with a laser source 2, a laser processing head 4 and a workpiece carrier 5. Laser light generated by a laser light source 2The beam 6 is guided by means of the beam guiding device 3 by means of a deflection mirror (not shown) to the laser processing head 4 and is focused therein, and is oriented perpendicularly to the surface 8a of the workpiece 8 by means of a mirror (also not shown), i.e. the beam axis (optical axis) of the laser beam 6 extends perpendicularly to the workpiece 8. In the example shown, the laser source 2 is CO ₂ A laser source. Alternatively, the laser beam 6 may be generated by a solid state laser, for example.

For laser cutting of the workpiece 8, the workpiece 8 is first pierced by means of the laser beam 6, i.e. the workpiece 8 is melted or oxidized in a punctiform manner at the piercing point E and the melt formed there is blown out. Next, the laser beam 6 is moved over the workpiece 8, so that a common cutting profile 9 is formed, along which the laser beam 6 separates the workpiece 8.

Not only penetration but also laser cutting may be assisted by the addition of gas. Oxygen, nitrogen, compressed air and/or a specific purpose gas may be used as the cutting gas 10. The particles and gases formed can be sucked away from the suction chamber 12 by means of the suction device 11.

The laser processing machine 1 also comprises movement means 13 for moving the laser processing head 4 and the workpiece 8 relative to each other. In the example shown, the workpiece 8 rests on the workpiece carrier 5 during machining and the laser machining head 4 moves during machining along two axes X, Y of the XYZ coordinate system. For this purpose, the movement device 13 has a gantry 14 which can be moved in the X-direction by means of a drive indicated by double arrow. The laser processing head 4 can be moved in the X direction by means of a further drive of the movement device 13, which drive is indicated by a double arrow, in order to be moved in the X direction or in the Y direction to an arbitrary processing head position B in a working field predefined by the mobility of the laser processing head 4 or by the workpiece 8. The laser beam 6 has a (momentary) feed speed v at the respective processing head position B.

As can be seen in fig. 2a, the laser beam 6 is focused onto the workpiece 8 by means of a focusing device in the form of a focusing lens 15 in order to perform a cutting process on the workpiece 8. In the example shown, the focusing lens 15 is a lens made of zinc selenide which focuses the laser beam 6 through the laser processing nozzle 16, more precisely through the nozzle opening 16a of the laser processing nozzle, onto the workpiece 8, in particular in the example shown onto the focal position F on the surface 8a of the workpiece 8. There, the laser beam 6 forms an interaction region 17 with the workpiece 8, behind which a cutting profile 9 shown in fig. 1 is produced opposite to the machining direction V or opposite to the cutting direction of the laser cutting process. In case the laser beam 6 originates from a solid state laser, a focusing lens, for example made of quartz glass, may be used.

Fig. 2a also shows a deflection mirror 18, which is embodied as semitransparent, and reflects the incident laser beam 6 (for example, having a wavelength of approximately 10.6 μm) and transmits the observation radiation, which is important for process monitoring, to a second, transparent deflection mirror 19. In the example shown, the deflection mirror 18 is constructed to be translucent for viewing radiation in the form of thermal radiation with a wavelength λ of approximately 700nm to 2000 nm. The irradiation source 21 is used to irradiate the workpiece 8 coaxially with irradiation radiation 22. The irradiation radiation 22 is transmitted by the other half of the transmissive deflection mirror 19 and by the deflection mirror 18 and deflected onto the workpiece 8 through the nozzle opening 16a of the laser processing nozzle 16.

Instead of semi-transparent deflection mirrors 18, 19, it is also possible to use a doctor blade mirror (scrapigel) or a hole mirror (lochskiegel) which reflects only the incident radiation from the edge region in order to deliver the irradiation radiation 22 to the workpiece 8. At least one mirror which is laterally introduced into the beam path of the laser beam 6 can also be used in order to be able to observe.

The diode laser or LED or flash lamp may be provided as an illumination source 21, which as shown in fig. 2a may be arranged coaxially with respect to the laser beam axis 24, but may also be arranged off-axis. The irradiation source 21 can also be arranged, for example, outside the laser processing head 4 (in particular beside the laser processing head) and aligned to the workpiece 8; alternatively, the irradiation source 21 may be arranged within the laser processing head 4, but not oriented coaxially with the laser beam 6 onto the workpiece 8. The laser processing head 4 can also be operated without the irradiation source 21 if necessary.

A position-resolving detector in the form of a high-geometry-resolution camera 25 is arranged in the observation beam path 23 behind the further semitransparent deflection mirror 19. The camera 25 may be a high-speed camera which is arranged coaxially with respect to the laser beam axis 24 or with respect to an extension of the laser beam axis 24 and thus independent of direction. In the example shown, an image is recorded by means of the camera 25 in the near-infrared/infrared wavelength range by means of incident light irradiation, in order to record the thermal image of the process itself or of the cutting process. In the example shown in fig. 2a, a filter may be arranged in front of the camera 25 when another radiation component or wavelength component should be excluded from sensing by means of the camera 25. The filter may be configured, for example, as a narrow-band bandpass filter having a half-value width of, for example, about 15nm, which transmits a wavelength λ in the range of about 800 nm.

In order to sense the surface area O, O' of the workpiece 8 shown in fig. 4a, b on the detector surface 25a of the camera 25 in a point-resolved manner, the laser processing head 4 has imaging optics 27. In the example shown, the imaging optics 27 have a diaphragm 28 rotatably mounted about a central rotation axis D, so that the position of the eccentrically arranged diaphragm opening 28a moves in an arc about the rotation axis D during rotation (see fig. 2 b).

By arranging the aperture 28 in the beam path of the imaging optics 27 focused by means of the lens 29, only a part of the beam path 23 is observed through the aperture opening 28a arranged eccentrically with respect to the extension of the beam axis 24 of the laser beam 6 and forms an observation beam 23a imaged on the detector surface 25a, which passes through the edge region of the focusing lens 15 and is oriented at an angle β with respect to the beam axis 24 of the laser beam 6 in the converging beam path after the focusing lens 15. In the example shown in fig. 2, the viewing direction R1 of the viewing beam 23a extends in a projection in the XY-plane or workpiece plane parallel to the direction of the machining vector V along which the laser beam 6 and the workpiece 8 are moved relative to each other in the X-Y plane in order to form the desired cutting profile, i.e. to make a penetrating view (stechende Beobachtung). In the example shown, the angle β (the viewing direction R1 being oriented at this angle relative to the beam axis 24 of the laser beam 6) is between about 1 ° and about 5 °, for example about 4 °.

Instead of a mechanically adjustable aperture 28, an electrically adjustable aperture, for example in the form of an LCD array, can also be used, in which individual pixels or groups of pixels are switched on or off electronically in order to produce an aperture effect. Unlike what is shown in fig. 2a, b, the mechanical aperture 28 can also be moved or moved transversely to the observation beam path 23, for example in the YZ plane, in order to mask different parts of the observation beam path 23 or to open these parts for observation. The aperture 28 may also be realized in the form of one or more mechanical elements that are openable and closable. Unlike the illustration in fig. 2a, b, the aperture 28 can also be omitted entirely, i.e. the processing beam path 23 is imaged completely onto the detector surface 25 a.

Fig. 3 shows a workpiece 8 to be processed, more precisely a workpiece surface 8a, having a predefined desired movement path 9' along which the workpiece 8 is to be cut in order to produce the desired cutting profile 9 shown in fig. 1. The predefined intended movement path 9' extends from the penetration position E described above to the end position T and has a semicircular path section, to which a linear path section is connected. Due to the axial vibration of the processing head 4, more precisely of the drive shaft of the movement device 13, the actual cutting profile (not shown) produced during the movement along the predefined intended movement path 9' of the processing head 4 does not exactly correspond to the (intended) cutting profile 9 shown in fig. 1, which is intended to be produced on the workpiece 8 during the cutting operation.

In order to correct the profile deviations due to vibrations, the following steps are performed prior to machining: in step a), the laser processing head 4 is moved along a predefined intended movement path 9 'over the stationary workpiece 8, i.e. the laser processing head 4 is guided along the intended movement path 9' between the penetration position E and the end position T. The movement of the laser processing head 4 is controlled by means of a control device 34 (see fig. 1), which also takes on other control tasks of the laser cutting machine 1 and is connected to the evaluation device 30 in a signal-technical manner.

By means of an evaluation device 30 which is connected to the detector 25 in signal technology, in step b) the relative movement 31 between the laser processing head 4 and the workpiece 8 is determined using the optical detector 25, as described in further detail below. Based on the determined relative movement 31 between the laser processing head 4 and the workpiece 8, in step c) a corrected desired movement path 9 is determined in the evaluation device 30, the control device 34 or another device, which is also shown in fig. 3. The corrected due motion profile 9 compensates for the profile error due to the drive shaft vibration of the laser processing head 4 described further above. If the laser processing head 4 is moved along the corrected intended movement path 9 shown in fig. 3, a desired cutting contour 9 shown in fig. 1 is produced in the subsequent processing during the cutting of the workpiece 8, which cutting contour corresponds to the predetermined intended movement path 9' (irrespective of deviations or overshoots).

In order to determine the relative movement 31 or the actual movement path when the laser processing head 4 is moved along the desired movement path 9', the irradiation radiation 22 of the irradiation source 21 irradiates the surface 8a of the workpiece 8 through the nozzle opening 16a of the processing nozzle 16. The surface area O sensed through the nozzle opening 16a at the surface 8a of the workpiece 8 in the region of the processing head 4 or at the respective processing head position B along the predefined intended movement path 9' is imaged by means of imaging optics 27 onto the detector surface 25a of the position-resolving detector 25.

Fig. 4a shows the irradiation radiation 22 reflected on the surface region O shown in fig. 3, more precisely the reflection pattern 32 of the surface 8a of the workpiece 8 in the surface region O at the processing head position B shown in fig. 3. Fig. 4B shows a reflection pattern 32' or image of the surface region O ' which was recorded at a later point in time than the reflection pattern 32 shown in fig. 4a at a further processing head position B '. The time offset between the recordings of the two images of the surface region O, O ' or of the associated reflection pattern 32, 32' is selected such that the two surface regions O, O ' (partially) overlap, as is shown in fig. 4 b.

From a comparison between the temporally successive reflection patterns 32, 32' of the two surface regions O, O ', a lateral offset between the relative movement 31, more precisely the two surface regions O, O ', can be ascertained. The lateral offset 31 corresponds to the direction and magnitude of the feed speed v of the processing head 4 at the processing head position B of the surface area O shown in fig. 3. As can be seen in fig. 4b, the lateral offset 31 does not have to extend horizontally or in the negative Y-axis direction as in the case of the predefined due trajectory curve 9 'shown in fig. 3 in the straight trajectory section, but rather the direction of the lateral offset 31 deviates from the predefined due trajectory 9', in particular in the X-direction by a difference (deviation) 33 shown in fig. 4 b.

When the laser processing head 4 is moved along the predefined desired movement path 9' shown in fig. 3, a deviation 33 of the actual movement path can be determined at each processing head position B in that: the analysis evaluates the temporally successive reflection patterns 32, 32 'of the respectively overlapping surface regions O, O'. In this way, the corrected machining path 9 shown in fig. 3 can be determined in the evaluation device 30, the control device 34 or another device of the laser processing machine 1 or in a device connected to the laser processing machine in signal technology. In this corrected due machining path 9, the deviation 33 is compensated for by a change in the predefined due machining path 9', so that the desired linear path section of the cutting profile 9 shown in fig. 1 is produced.

Instead of determining the deviation 33 from the relative movement 31, the deviation 33 may also be determined in a manner described further below in connection with fig. 5a, b. The following steps are performed before machining: in a first step a), the laser processing head 4 is moved over the stationary workpiece 8 along the predefined setpoint movement path 9 'shown in fig. 3, i.e. the laser processing head 4 is guided along the predefined setpoint movement path 9' between the penetration position E and the end position T. The (first) movement along the predefined desired movement path 9' takes place at a first relative speed or feed speed v ₁ The speed is so low that practically no deviations from the predefined desired movement path 9 'due to vibrations occur, i.e. the laser processing head 4 practically exactly follows the predefined desired movement path 9'.And (5) movement.

The irradiation radiation 22 reflected on the surface 8a of the workpiece 8 in the region of the processing head 4 is detected in a position-resolved manner during the movement, as described above in connection with fig. 4a, b. For the surface region O at the machining head position B shown in fig. 3, fig. 5 shows the reflected illumination radiation 22 sensed in a point-resolved manner, more precisely the reflection pattern 32a of the surface 8a of the workpiece 8 in the surface region O.

Subsequently, in step a), the laser processing head 4 is moved again along the predefined desired movement path 9 'over the stationary workpiece 8, i.e. the laser processing head 4 is moved again along the predefined desired movement path 9' between the penetration position E and the end position T at a second, greater relative speed or feed speed v ₂ Is guided. Here, the second relative velocity v ₂ Corresponding to the due relative speed at the subsequent processing of the workpiece 8. In a second movement along the predefined intended trajectory 9', the irradiation radiation 22 reflected on the surface 8a of the workpiece 8 is also sensed in a location-resolved manner. Fig. 5B shows a reflection pattern 32B or image of the surface region O ' which is recorded at a second movement at a processing head position B ', which corresponds to the processing head position B shown in fig. 3 along the predefined intended movement path 9', but is offset transversely (in the X-direction) with respect to the processing head position B due to the axial vibrations.

In a second step b), a difference or deviation 33 between the machining head positions B, B 'is determined by means of an evaluation device 30 connected to the detector 25 in signal engineering by comparing the first and second reflection patterns 32a, 32b of the two mutually overlapping surface areas O, O'. As can be seen by a comparison between fig. 4b and fig. 5b, in the method described in connection with fig. 5a, b, the same amount of deviation 33 is found as in the method described above. In a subsequent step c), a correction of the predefined intended movement path 9', or a compensation of the path error, takes place in the manner described above, i.e. by determining and correcting the deviation 33 at each machining head position B along the predefined intended machining path 9'.

If necessary, the steps a) and b) described above can be repeated in order to check whether the desired cutting profile 9 is produced on the workpiece 8 when the laser processing head 4 is moved along the corrected intended movement path 9, i.e. whether the predetermined intended movement path 9' is reproduced on the workpiece 8 as precisely as possible when the processing head 4 is moved along the corrected intended movement path 9. If this is not the case, step c) can be re-performed if necessary, i.e. a further corrected due movement path 9 can be determined and steps a) and b) can be re-performed in order to check whether the deviation 33 of the corrected due movement path 9' from the actual movement path is sufficiently small. If appropriate, steps a), b) and c) can be carried out successively in multiple times until the deviation 33 along the entire corrected intended movement path 9 falls below a predefined value or until an interruption criterion, for example a predefined number of repetitions, is reached.

To compare the reflective patterns 32, 32';32a, 32b for determining the relative movement 31 or the deviation 33, a pattern recognition algorithm is implemented in the evaluation device 30, which calculates the two reflection patterns 32, 32';32a, 32b, from which the reflection pattern 32, 32 'in the overlapping surface area O, O' is determined; 32a, 32b are the most similar image portions. Details of examples of such pattern recognition algorithms can be found in DE102005022095A1 or DE102006049627A1 cited at the outset.

In summary, in the manner described above, the cutting profile 9 to be produced during the cutting process can be reproduced with a high degree of accuracy without the dynamics, i.e. the processing speed, being reduced during the cutting process. The method described above can also be carried out in other processing operations, for example during the welding process of the workpiece 8, in order to predefine the corrected movement path 9 for producing the weld seam or welding contour to be formed with the greatest possible accuracy.

Claims

1. A method for machining a workpiece (8) by means of a machining beam (6), the method comprising:

before processing:

a) The processing head (4) and the workpiece (8) are moved relative to each other along a predefined defined movement path (9'),

b) By means of an optical detector (25) which is fixedly connected to the processing head (4), a relative movement (31) between the processing head (4) and the workpiece (8) is determined when moving along the predefined desired movement path (9'), and

c) The corrected due motion trail (9) is obtained according to the obtained relative motion (31),

the method further comprises:

processing the workpiece (8) by directing the processing beam (6) onto the movement of the processing head (4) and the workpiece (8) relative to each other along the corrected due movement trajectory (9),

irradiating the surface (8 a) of the workpiece (8) with irradiation radiation (22) in the region of the processing head (4), wherein the irradiation of the surface (8 a) of the workpiece (8) takes place slightly obliquely with respect to the processing beam (6),

-detecting the irradiation radiation (22) reflected on the surface (8 a) of the workpiece (8) in the region of the processing head (4) in a spot-resolved manner in order to obtain, when moving along the predefined intended movement path (9 '), temporally successive reflection patterns (32, 32 ') of the overlapping surface region (O, O ') of the workpiece (8), and

the relative movement (31) is determined by comparing the reflection patterns (32, 32') that are successive in time.

2. A method for machining a workpiece (8) by means of a machining beam (6), the method comprising:

before processing:

a) The processing head (4) and the workpiece (8) are moved relative to each other along a predefined desired movement path (9') at a first relative speed (v) ₁ ) The motion of the person is performed,

-moving the machining head (4) and the workpiece (8) relative to each other along the predetermined desired movement path (9') at a second, greater relative speed (v) ₂ ) The motion of the person is performed,

b) By means of the processing head(4) The fixedly connected optical detector (25) determines the first relative speed (v) along the predefined desired movement path (9') ₁ ) The movement performed and the movement path (9') along the predetermined desired movement path (v) are performed at the second relative speed (v ₂ ) Deviation (33) between the movements performed, and

c) The corrected due motion trail (9) is obtained according to the obtained deviation (33),

the method further comprises:

-machining the workpiece (8) by means of a movement of the machining head (4) and the workpiece (8) relative to each other along the corrected due movement trajectory (9) with the machining beam (6) directed onto the workpiece (8).

3. The method according to claim 2, in which the determination of the deviation (33) comprises:

irradiating a surface (8 a) of the workpiece (8) with irradiation radiation (22) in the region of the processing head (4),

-detecting in a spot-resolved manner the irradiation radiation (22) reflected on the surface (8 a) of the workpiece (8) in the region of the processing head (4) in order to detect the irradiation radiation at the first relative speed (v) along the predefined desired movement path (9') ₁ ) A first reflection pattern (32 a) of the overlapping surface area (O, O ') of the workpiece (8) is obtained during movement and the second relative speed (v) is set along the predefined intended movement path (9') ₂ ) A second reflection pattern (32 b) which, when in motion, acquires an overlapping surface area (O, O') of the workpiece (8), an

The deviation (33) is determined by comparing the first and second reflection patterns (32 a, 32 b).

4. A method according to claim 1 or 3, in which method the irradiation and the location-resolved sensing of the surface area (O, O') takes place through processing optics of the processing head (4).

5. A method according to any one of claims 1 to 3, in which method at least the steps a) and b) are performed again, wherein the corrected due motion profile (9) determined in the preceding step c) constitutes the predetermined due motion profile (9') when the steps a) and b) are performed again.

6. A method according to claim 4, in which method the processing optics are focusing optics (15).

7. A machine for machining a workpiece (8), the machine comprising:

a machining head (4) for machining the workpiece (8), which is designed for directing a machining beam (6) onto the workpiece (8),

-a movement device (13) for moving the machining head (4) and the workpiece (8) relative to each other, and

an optical detector (25) fixedly connected with the processing head (4),

characterized by comprising:

a control device (34) which is designed to move the machining head (4) and the workpiece (8) relative to one another along a predefined desired movement path (9') prior to machining,

an evaluation device (30) for determining a relative movement (31) between the processing head (4) and the workpiece (8) when moving along the predefined desired movement path (9') by means of the optical detector (25) and a corrected desired movement path (9) from the determined relative movement (31), and wherein the control device (34) is configured for moving the processing head (4) and the workpiece (8) relative to one another along the corrected desired movement path (9) during processing,

wherein the optical detector (25) is designed for the spatially resolved detection of the irradiation radiation (22) reflected on the surface (8 a) of the workpiece (8) in the region of the processing head (4) in order to obtain, when moving along the predefined intended movement path (9 '), temporally successive reflection patterns (32, 32') of the overlapping surface region (O, O ') of the workpiece (8), wherein the irradiation of the surface (8 a) of the workpiece (8) is carried out slightly inclined with respect to the processing beam (6), and wherein the evaluation device (30) is designed in the processing machine for determining the relative movement (31) by comparing the temporally successive reflection patterns (32, 32').

8. A machine for machining a workpiece (8), the machine comprising:

an optical detector (25) fixedly connected with the processing head (4),

characterized by comprising:

a control device (34) configured for bringing the processing head (4) and the workpiece (8) relative to each other at a first relative speed (v ₁ ) And at a second, greater relative velocity (v ₂ ) Along a predefined desired movement path (9'),

an evaluation device (30) for determining a deviation (33) between a movement along the predefined movement path (9 ') at the first relative speed (v 1) and a movement along the predefined movement path (9') at the second relative speed (v 2) by means of the optical detector (25) and for determining a corrected movement path (9) from the determined deviation (33), and wherein,

the control device (34) is designed to move the machining head (4) and the workpiece (8) relative to one another during machining along the corrected intended movement path (9).

9. The machine of claim 8, in which the optical detector (25) is configured for location-resolved sensing at the workpiece(8) Is reflected on the surface (8 a) of the processing head (4) in the region of the irradiation radiation (22) so as to be at the first relative speed (v ₁ ) A first reflection pattern (32 a) of the overlapping surface area (O, O ') of the workpiece (8) is obtained during movement and the second relative speed (v) is set along the predefined intended movement path (9') ₂ ) A second reflection pattern (32 b) of the overlapping surface area (O, O') of the workpiece (8) is obtained upon movement,

and in the processing machine, the evaluation device (30) is designed to determine the deviation (33) by comparing the first and second reflection patterns (32 a, 32 b).

10. The processing machine according to any one of claims 7 to 9, further comprising: an illumination source (21) for illuminating a surface (8 a) of the workpiece (8) with illumination radiation (22).

11. The machine of claim 7 or 9, configured for illuminating a surface (8 a) of the workpiece (8) through machining optics of the machining head (4) and for sensing the surface area (O, O') with a point resolution.

12. A processing machine according to claim 7 or 8, in which the processing machine is a laser processing machine (1).

13. A processing machine according to claim 11, in which the processing optics are focusing optics (15).