Laser machining method, and laser machine tool

Abstract

The invention relates to a laser machining method, a laser machine tool, and a computer programme product. The aim of the invention is to provide a laser machine tool and a laser machining method as well as a computer programme product by means of which malfunctions are reduced. For this purpose, a laser machining method is provided that comprises the following steps: - defining at least one threshold value SO with respect to a light-intensity-dependent first process variable F in at least one working range KAB or one working point KAP; - detecting a light-intensity-independent second process variable K during the operation of a laser machine tool (10) in a working range KAB or working point KAP; - determining a change in the first process variable F in the at least one working range KAB or in the working point KAP under changed process conditions; - changing the at least one threshold value SO to a threshold value SOR corresponding to the change in the first process variable F from a value FO to a value FOR.

Description

[0001] Laser processing method and laser processing machine

[0002] The invention relates to a laser processing method, a laser processing machine and a computer program product according to the preamble of the independent claims.

[0003] The technical field of industrial processing of various materials using laser radiation is becoming increasingly important. When cutting workpieces made of various materials, for example, laser radiation from a laser processing machine or laser cutting machine with high power, usually in the range of several kilowatts, is used. To monitor laser processing processes, laser processing machines are assigned sensor devices that can record a variety of measured variables that are then evaluated in a control device. One example of a sensor device is a camera that records the spatially resolved light intensity on a processed workpiece as a measured variable. Various conclusions can be drawn from the light intensities regarding the quality of the processing. These conclusions can be used for monitoring functions and control functions of the laser processing machine.For example, it can be used to detect a cut break during laser cutting. A cut break refers to an undesired cut that does not go completely across the entire width of the workpiece. Changes in process conditions can lead to a previously calibrated and functional sensor device operating incorrectly. These changes in process conditions can have various causes. Firstly, there are faults or deviations in the laser processing machine, such as dirty protective glass, heating of the optics or a change in the purity of a gas jet. These faults or deviations affect the laser processing process or the detection by the sensor device. Secondly, there are deviations in the material to be processed, such as the sheet thickness of a workpiece, the surface quality, the material composition or material inclusions.These deviations can influence the process and the process control of the laser processing. Thirdly, deviations in the selected process control, such as a changed focus position, a changed focus diameter, changes in the distance from the workpiece to a nozzle at the exit of the laser beam or a changed gas pressure. This means that existing miscuts are not detected or non-existent miscuts are detected incorrectly. One measure in the state of the art is a further calibration process of the laser processing machine with sensor device, which is usually carried out in separate work steps, i.e. outside of the machine running time. For example, it is necessary to recalibrate with regard to the transmission of the process radiation through the optical elements used and the sensor device or due to decreasing sensitivity of the sensor.

[0004] An object of the invention is to provide a laser processing machine and a laser processing method as well as a computer program product with which malfunctions are reduced.

[0005] For this purpose, a laser processing method is provided with the following process steps

[0006] • Setting at least one threshold value So with respect to a first light intensity-dependent process variable Fo in at least one working area KAB or one working point KP; • Detecting a second, light intensity-independent process variable K during operation of a laser processing machine (10) in at least one working area KAB or at the working point KP;

[0007] • Determining a change in the first process variable Fo in the working range KAB or working point KAP when the process conditions change;

[0008] • Changing at least one threshold value So to a threshold value SOR in accordance with the change in the first process variable FQR .

[0009] In addition, a computer program product is provided in an evaluation device for carrying out the laser processing method.

[0010] Furthermore, a laser processing machine is provided with an evaluation device, wherein the evaluation device is designed to define at least one threshold value So with respect to a light intensity-dependent first process variable F in at least one working area KAB or a working point KAP, to detect a light intensity-independent second process variable K during the operation of a laser processing machine in a working area KAB or working point KAP ZU, to determine a change in the first process variable F in at least one working area KAB or in the working point KAP under changed process conditions and to convert the at least one threshold value So to a threshold value SOR in accordance with the change in the first

[0011] Process variable F is changed from a value Fo to a value FOR ZU. Embodiments of the invention are described in the dependent claims.

[0012] In one example, a control setpoint R of the laser processing process is assigned to the threshold value So, and the control setpoint R is changed to a control setpoint ROR according to the change in the first process variable F from a value Fo to a value FQR. If the first process variable F changes, the control setpoint is changed.

[0013] In one example, in the control process step, the second process variable K is the overtravel length or the angle of inclination of a cutting front on a workpiece to be cut. The overtravel length describes the length in the feed direction of the workpiece from the cutting front on the top side to the cutting front on the underside of the workpiece. The angle of inclination of the cutting front can be measured from the top side to the underside of the workpiece. These process variables K have proven to be particularly suitable for the functionality because they can be recorded independently of light intensity, hereinafter also intensity-independent.

[0014] In a further example, the process step of changing the threshold value So to the threshold value SQR in the working point KAP or in the working area KAB is carried out according to a light intensity recorded on the workpiece or a process variable which depends on the light intensity, as the first process variable F.

[0015] Based on the modified threshold value SQR, a malfunction of the laser processing machine can be determined, or a monitoring or control variable that is less dependent on changes in light intensity can be stabilized. Advantageously, a malfunction is detected using the modified threshold value SOR, which better reflects the actual characteristics of the laser processing machine under changed conditions than the originally defined threshold value S0. In the context of the present disclosure, the term "malfunction" also refers to faulty or undesirable processing processes and processing errors.

[0016] In one example, a cut break is detected as a malfunction based on the changed threshold value SOR. The changed threshold value SOR serves to reliably detect a cut break and to prevent false detection of a cut break or non-detection of a cut break with an unchanged threshold value So. Thus, in the first case, either no malfunction exists, but a malfunction is incorrectly detected. In the second case, a malfunction exists, but no malfunction is detected.

[0017] It was advantageously found that malfunctions of the laser processing machine can be effectively reduced by changing the threshold value So proportionally to the threshold value SOR in accordance with the changed first process variable F.

[0018] Furthermore, the threshold value SOR can be continuously changed in a control process of the laser processing method.

[0019] The threshold value SOR of the light intensity-dependent first process variable F is adjusted by control technology.

[0020] In another example, the control process or the control is carried out using the second process variable K as the controlled variable, with the manipulated variable being a feed rate of the workpiece in the laser processing machine or the power supply of the laser processing machine. Thus, the controlled variable, the second process variable K, is adjusted by adjusting the aforementioned manipulated variables.

[0021] In one example, the threshold value So is changed or adjusted continuously or iteratively. This ensures that the threshold value So always corresponds to the current conditions of the laser processing machine. This measure can achieve particularly high process stability. The first process variable F is recorded depending on the location and / or direction. The threshold value So can be adjusted accordingly depending on the location and / or direction. This allows anisotropies or inhomogeneities of the laser processing machine in its work area to be taken into account and compensated for. Alternatively or additionally, the changes in the first process variable F can be recorded depending on the time and the threshold value So can be adjusted depending on the time. When adjusting the threshold value So, it can also be taken into account how long the information about a cutting location or a cutting direction has been available or how long ago the information about a cutting location or a cutting direction was available.If a cut was made in the same cutting direction just a few seconds previously, it is more likely that the laser processing machine is still in a similar state, whereas a cut made a minute or more later makes it more likely that the laser processing machine is no longer in the same state. The threshold value So can therefore also be a function of the temporal progression of the available information. Temporal aspects can thus be taken into account when adjusting the threshold value So.

[0022] Examples of the invention are described in detail below with reference to the figures. They show:

[0023] Fig. 1 is a schematic representation of a device for monitoring a laser processing process, in particular a laser cutting process, as part of a laser processing machine by recording an image of a region of the workpiece to be monitored, which region contains an interaction region,

[0024] Fig. 2 is a schematic representation of a laser processing machine with a further device for monitoring a laser processing process, in particular a laser cutting process,

[0025] Fig. 3 shows a qualitative diagram with threshold values ​​S of a first process variable F on the y-axis, a second process variable K on the x-axis, characteristic curves with working areas and an operating point and a miscut area of ​​the laser processing machine during operation.

[0026] Fig. 1 shows an exemplary structure of a device 14 for process monitoring and process control of a laser processing method, in particular a laser cutting process, on a workpiece 8 by means of a laser processing machine 1, of which the laser processing head 4 with a focusing lens 15 for focusing a laser beam 6 of the laser processing machine 1, a cutting gas nozzle 16 and a deflecting mirror 17 are shown only very schematically. Other components can be included in the laser processing head 4. In the present case, the deflecting mirror 17 is partially transparent and forms an entry-side component for the device 14 for process monitoring. The laser beam 6 has a high power for processing the workpiece 8, in this case for cutting or separating the workpiece 8.The deflecting mirror 17 reflects the incident laser beam 6, which, for example, has a wavelength of approximately 10 lm or 1 lm in the case of a solid-state laser used, and transmits radiation relevant for process monitoring, process radiation 19, which is reflected by the workpiece 8 and emitted by an interaction region 18 of the laser beam 6 with the workpiece 8, in a wavelength range which, in the present example, lies between approximately 300 nm and 2000 nm. As an alternative to the partially transparent deflecting mirror 17, a scraper mirror or a pinhole mirror can also be used to feed the process radiation 19 to a camera 21.

[0027] In the device 14, behind the partially transparent deflecting mirror 17 in the direction of the process radiation 19, a further deflecting mirror 20 is arranged, which deflects the process radiation 19 onto the geometrically high-resolution camera 21 as the image capture unit. The camera 21 can be a high-speed camera which is arranged coaxially to the laser beam axis 22 or to the scanning beam axis 22a of a scanning beam and is therefore independent of direction. In principle, it is possible for the camera 21 to also record the image using the incident light method between approximately 300 nm and 2000 nm, provided that an additional illumination source radiating in this wavelength range is provided, and alternatively to record the inherent process luminosity or process radiation 19 in the UV and NIR / IR wavelength ranges. The camera 21 can also be provided as the only image capture unit, so that no additional scanning beam is necessary.In both cases, the camera 21 detects the process radiation 19 or the process light from the interaction area 18 .

[0028] For imaging, in the present example, an imaging, focusing optical system 23, shown as a lens in Fig. 1, is provided between the partially transparent mirror 17 and the camera 21, which focuses the radiation or process radiation 19 relevant for process monitoring onto the camera 21. In the example shown in Fig. 1, a filter 24 in the direction of the process radiation 19 in front of the camera 21 is advantageous if further radiation components or wavelength components are to be excluded from detection by the camera 21. The filter 24 can, for example, be designed as a narrow-band bandpass filter.

[0029] In the present example, the camera 21 is optionally operated using the incident light method, i.e. an additional illumination source 25 is provided above the workpiece 8, which couples illumination radiation 27 coaxially to the laser beam axis 22 into the beam path via a further partially transparent mirror 26. In principle, however, the intensity of the process radiation 19 generated during laser processing is sufficient. The respective beam paths are coaxial in the vertical direction according to Fig. 1. Laser diodes or diode lasers can be provided as additional illumination source 25, which can be arranged coaxially as shown in Fig. 1, but also off-axis to the laser beam axis 22. The additional illumination source 25 can, for example, also be arranged outside, in particular next to the laser processing head 4 and directed onto a surface 8a of the workpiece 8.Alternatively, the illumination source 25 can be arranged within the laser processing head 4. It is understood that the device 14 can also be operated without an additional illumination source 25.

[0030] In the example shown in Fig. 1, during a laser fusion cutting process or laser flame cutting process the camera 21 takes an image B of a region 28 of the workpiece 8 to be monitored, which region contains the interaction region 18. During the cutting process by the laser beam 6 a relative movement occurs between the workpiece 8 and the laser processing head 4 due to the movement of the laser processing head 4 along the positive Y direction (see arrow) at the relative speed referred to as feed speed V. The laser processing head 4 is also moved within the two planes in the x direction and z direction. During the cutting process a cutting front 29 is formed in the lead to the interaction region 18, to which a kerf 9 is connected in the trailing direction, in the negative Y direction, in the workpiece 8.

[0031] The image capture unit, designed as a camera 21, is connected to an evaluation device 30 by means of signals. The evaluation device 30 is configured or programmed to detect at least one malfunction in the machining process, for example, a broken cut, based on the evaluation of the recorded image B or a temporal sequence of images B of the area 28 to be monitored. The camera 21 and the evaluation device 30 form a sensor device.

[0032] The evaluation device 30 evaluates the image B or a series of consecutively recorded images B of the interaction region 18 in order to extract or identify features of the interaction region 18 that indicate a disturbance in the cutting process.

[0033] As can be seen in Fig. 1, the evaluation device 30 is in signal-technical connection with a control device or regulating device 31, which controls or regulates the laser cutting process and the laser processing method.

[0034] Fig. 2 shows a side view of a laser processing machine 1, shown very schematically. For monitoring a laser processing method, in particular a laser cutting process, the camera 21 and the connected evaluation device 30 are included, similar to Fig. 1. The laser processing machine 1 is a laser cutting system. The workpiece 8, in this case a sheet metal, lies on the workpiece support 5 of the laser processing machine 1. The laser processing machine 1 has the laser processing head 4, which is a cutting head. The laser processing head 4 can be moved along a first translational axis 32, a second translational axis 33 and along an axis in the image plane relative to the workpiece support 5. Furthermore, the laser processing head 4 can be rotated about one or more rotational axes in a manner not shown in more detail.

[0035] For processing, for example cutting, the workpiece 8, the laser processing head 4 or cutting head emits the laser beam 6. The workpiece 8 is cut through along a trajectory by means of the laser beam 6. To support the processing of the workpiece 8 with the laser beam 6, the laser processing head 4 has the cutting gas nozzle 16. A cutting gas is supplied to the workpiece 8 through the cutting gas nozzle 16. The laser processing head 4 can further have a protective glass 34 for an optical system not shown in detail in Fig. 2.

[0036] The laser processing machine 1 has the evaluation device 30 similar to Fig. 1 , furthermore the control device 31 can be connected to the evaluation device 30 in terms of signal technology. The evaluation device 30 and the connected control device 31 carry out the cutting process by specifying and adapting various process parameters or process variables F, K. Two of the process parameters can be, for example, a feed rate v and a focus position f, i.e. the position of the focus of the laser beam 6 relative to the workpiece 8. Further process parameters or process variables can be a laser power, a focus diameter, a gas pressure of the cutting gas before it exits the cutting gas nozzle 16, a mass flow or the composition of the cutting gas through the cutting gas nozzle 16 and / or a distance of the cutting gas nozzle 16 from the workpiece 8.

[0037] Fig. 3 shows a qualitative diagram to explain an example of the invention. It has been recognized that under normal processing conditions, light intensity-dependent or intensity-dependent process variables can be used to clearly differentiate between a faulty cut and a good cut. The process variables depend to varying degrees on the light intensity detected by the camera 21 and the sensor device used. For example, the gray value of a camera pixel is proportional to the light intensity, while a geometric value in the camera image is independent of the light intensity. Nevertheless, geometric values ​​can also correlate with the light intensity, for example when threshold values ​​are used for gray values ​​of the camera images.

[0038] Under disturbed or difficult processing conditions, the intensity-dependent variables alone can no longer reliably detect malfunctions or disturbances in the processing process. Difficult processing conditions can occur, for example, in the case of disturbances in the light intensity of the scanning beam or the process radiation 19. Therefore, a second variable is introduced which is independent of the light intensity or less dependent on the light intensity. With the help of the second variable or process variable, malfunctions or disturbances in the processing process can be detected, thus reducing the susceptibility to disturbances of the laser processing method.

[0039] An intensity-independent or sufficiently intensity-independent second process variable K is shown on the x-axis, for example the overrun length, which denotes the distance in the feed direction from the cutting front 29 on the top side to the cutting front 29 on the bottom side of the workpiece 8. Another intensity-independent process variable K is the inclination angle of a cutting front 29, the angle between the top side and the bottom side of the workpiece 8 on the cut surface. These process variables K have proven to be particularly suitable for the functionality. On the y-axis, a first process variable F, in this example an intensity-dependent miscutting variable F, with threshold values ​​S o and S O R , in which in the evaluation device 30 after exceeding the threshold values ​​S o and S O R a cut break is detected by the faulty cut size F. Below the threshold values ​​S o or S OR, i.e. if F < S o or F < S O R, there is a

[0040] Good cut before . Above the threshold values ​​S o or S O R, i.e. if F > S o or F > S O R, there is a faulty cut. The condition F < S o applies to the non-updated threshold in undisturbed operation, if the threshold is not changed, the condition F > S O R applies to the updated threshold value in faulty operation if the threshold value has been changed. Optionally, the above conditions are used to detect a good cut or a faulty cut if the above conditions are met over a certain period of time. The threshold values ​​S o and S O R are each located on characteristic curves at the boundary of a defined miscut area, which is shown hatched in Fig. 3. In general, an updated threshold value S O R is a function of the fixed threshold So , the first process variable F, here the cutting error F, and the process variable K, where S O R = f ( F, K, S o ) . In particular, the

[0041] Threshold S o to the threshold value S O R is changed when the second process variable K is at the operating point KAP or in a working range KAB close to the operating point KAP. Several working ranges KAB can also be defined here. The working range KAB or the working ranges KAB can have any size, i.e. they can extend along the x-axis in Fig. 3, designated by the second process variable K, from a minimum measurable process variable K to the hatched miscut area. The control device or regulating device 31 can, for example, carry out a process stop of the laser processing machine 1 upon detection of a miscut.

[0042] For example, the control device 31 detects when the machining process deviates from the defined operating point KAP. The control device 31 can then guide the machining process back toward the defined operating point KAP by controlling process parameters or process variables.

[0043] Furthermore, the diagram shows the two characteristic curves of the laser processing machine 1 during operation, which show the course of the first process variable F or faulty cutting size F in relation to the second process variable K, whereby the dashed characteristic curve indicates laser processing without disturbances or malfunctions and the solid characteristic curve indicates laser processing with disturbances or malfunctions, as described below. In the diagram according to Fig. 3, the operating point KAP and an area along the process variable K around the operating point KAP are also entered, the operating range KAB - the measuring range of the laser processing machine 1 and the laser processing method is preferably at the operating point KAP or around the

[0044] Operating point KAP within the working range KAB - In the laser processing method, in the undisturbed process according to Fig. 3, the second process variable K lies in a working range KAB during operation of the laser processing machine 1 and in particular in controlled operation of the process variable K at the defined operating point KP. Accordingly, an operating point KAP is defined for which the process variable K = KAP and / or a working range KAB for which the process variable K lies in a range around the operating point KAP. The undisturbed miscut size Fo on the dashed characteristic curve designates undisturbed operation of the laser processing machine 1, in which the evaluation device 30 does not detect any malfunction. A threshold value So is defined for the operating point JQip, which indicates a malfunction of the laser processing machine 1, a threshold of the undisturbed miscut size, referred to in Fig. 3 as the undisturbed F threshold So.The threshold value So is set before operation of the laser processing machine 1, or alternatively during operation. If the faulty cut size F exceeds the threshold value So during laser processing, a malfunction is detected and a cut break is recognized. Optionally, the cut break is detected if the threshold value So is exceeded for a certain period of time. The malfunction can be reliably detected without any process changes to the laser processing machine 1.

[0045] If process changes occur during operation of the laser processing machine 1, for example due to contamination on the focusing lens 15, the first process variable F or miscut size F changes, which is detected by the evaluation device 30. Process changes or disturbances lead to a shift in the characteristic curve in Fig. 3. For example, the light intensity of the first process variable F, the miscut size F, changes if the laser beam 6 is disturbed by contamination, so that the camera 21 detects more process lights or process radiation 19 due to scattered radiation. A changed first process variable FQR in the working area KAB, specifically at the working point KAP, leads to a cut being incorrectly detected. This changed first process variable is referred to in Fig. 3 as disturbed F-variable FQR, i.e. disturbed miscut size. This false detection is shown in Fig. 3 as the note FQR > SO.The process changes lead to a shift in the first process variable F relative to the second process variable K. The characteristic curve as a functional relationship between the first process variable F and the second process variable K shifts. In Fig. 3 the disturbed miscutting variable F is shown as a solid characteristic curve. Without further measures a cut break will be falsely detected if the disturbed miscutting variable FQR is in the working range KAB and specifically at the working point KAP above the threshold value So, i.e. FQR > SO in Fig. 3. To remedy this situation a change in the first process variable FQR in the working range KAB and specifically at the working point KAP is determined which shows a deviation from undisturbed recorded values ​​of the first process variable Fo.If the machining process takes place in the working area KAB and specifically at the working point KAP, a threshold value SOR is determined, above which a cut break is recognized as a malfunction, FQR > SOR. This newly set threshold value SOR, referred to in Fig. 3 as the disturbed F threshold SOR, is located at a larger value, such as a higher detected light intensity of the process radiation 19. For example, the threshold value So can be changed to the threshold value SOR proportional to the detected disturbed miscutting size FQR according to the functional relationship SOR = p * (FOR / FO) with a proportionality factor p. If the miscutting size F changes by approximately 20%, i.e. (FOR / FO) = 1, 2 = p, the threshold value So is also increased by 20% compared to the threshold value SOR.If the miscut size moves above a threshold value So during operation, here due to a disturbed influence on the disturbed miscut size FQR, the evaluation device 30 falsely detects a malfunction. After moving or readjusting the threshold value So to a threshold value SOR, a malfunction is only detected at a higher first process variable F or miscut size F, whereby this corresponds to the actual conditions of the laser processing machine 1 during operation. The threshold value So is continuously adjusted or changed during operation of the laser processing machine 1. Accordingly, the changed threshold value SOR is then used to detect a cut break instead of the original threshold value So, which is changed accordingly to a further threshold value of the process variable Fo, whereby the threshold value SOR can be changed continuously.In particular, the threshold value SOR of the first light intensity-dependent process variable F can be continuously changed in a control process.

[0046] The functionality of the described laser processing machine 1 and the laser processing method is further illustrated by a hatched miscut area in Fig. 3. The miscut area represents the area in the diagram of the second process variable K in which the evaluation device 30 detects a cut break. The hatched miscut area is defined as a rectangular area by way of example, but can take on any shape in the diagram. In the hatched characteristic curve during undisturbed operation, the detected cut break is located at the

[0047] Threshold of the undisturbed miscut size So - In the case of the solid characteristic curve during disturbed operation, as described, the detected cut break is at the threshold of the disturbed miscut size SOR, which has a higher value of the intensity-dependent first process variable F .

[0048] The first process variable F can also be determined within the known operating range KAB if the operating point KAP is not reached in uncontrolled operation and the shape of the first process variable as the miscutting variable F is known in the corresponding range according to the characteristic curves in Fig. 3. Ideally, the second process variable K is controlled to the operating point KAP in order to minimize the operating range KAB ZU.

[0049] In a further example, a control setpoint R of the laser processing method is assigned to the threshold value So, and the control setpoint R is changed to a control setpoint ROR in accordance with the change in the first process variable F from a value Fo to a value FQR. If the evaluation device 30 detects a change in the first process variable F at the operating point KAP or operating range KAB, for example an increased light intensity due to a malfunction of the optical system 23, this increased light intensity would be incorrectly assigned to a changed overtravel length. With the control setpoint R, the laser processing machine 1 would undesirably change the speed of the feed of the workpiece 8 at the increased overtravel length. The correct overtravel length is determined using the light intensity-independent process variable K at the operating point KAP or operating range KAB.In order to ensure that the control of the feed speed of the workpiece 8 continues to be carried out reliably, the evaluation device.

[0050] 30 the control setpoint R is changed to the control setpoint ROR in such a way that the speed of the feed of the workpiece 8 remains regardless of the change in the first process variable F. This feature prevents the control process from being disturbed by erroneous light intensity-dependent measurements of the first process variable F. So to speak, the second process variable K corrects erroneous measurements of the first process variable F with respect to the control of the laser processing machine 1 by adjusting the control setpoint ROR. With adjustment to

[0051] Control setpoint ROR can also be the first process variable F despite

[0052] A malfunction, for example, of the optical system 23, can continue to be used reliably. Subsequent calibration of the first process variable F, which would be necessary without the measures described, is avoided. Accordingly, the principle of changing the control setpoint R corresponds to the principle of changing the threshold value at which a cut break is detected.

[0053] The described method for laser processing is also applicable to other technical fields and is not limited to the technical field of laser processing machines 1 . The described method is applicable in all technical fields in which process variables change and threshold values ​​are adjusted, changed or controlled automatically and without recalibration. List of reference symbols Laser processing machine Laser processing head Workpiece support Laser beam Workpiece a Surface Cutting kerf 0 Cutting gas 4 Device 5 Focusing lens 6 Cutting gas nozzle 7 Deflecting mirror 8 Interaction area 9 Process radiation 0 Additional deflecting mirror 1 Camera 2 Laser beam axis 2a Scanning beam axis 3 Optical system 4 Filter 5 Illumination source 6 Partially transparent mirror 7 Illumination radiation 8 Area to be monitored 9 Cutting front 0 Evaluation device 1 Control device 2 First translational axis 3 Second translational axis 4 Protective glass

Claims

Patent claims for laser processing methods comprising the following process steps: - Defining at least one threshold value So with respect to a light intensity-dependent first process variable F in at least one working range KAB or one operating point KAR; - Acquiring a light intensity-independent second process variable K during the operation of a laser processing machine ( 10 ) in a working area KAB or working point KAP; - Determining a change in the first process variable F in at least one working area KAB or in the operating point KAP under changed process conditions; - Changing at least one threshold value So to a threshold value SQR corresponding to the change in the first process variable F from a value Fo to a value FQR. Laser processing method according to claim 1, comprising the process step: - Assigning a control setpoint R of the laser processing process to the threshold value So; - Changing the control setpoint R to a control setpoint ROR corresponding to the change in the first process variable F from a value Fo to a Value FOR . Laser processing method according to claim 1 or 2, comprising the process step: - Rules of the second process variable K as the trailing length or inclination angle of a cutting front (29) on a workpiece (8) to be cut. Laser processing method according to one of the preceding claims, comprising the process step: - Changing at least one threshold value, such as the threshold value SOR, at the operating point KAP or in the working area KAB, according to a recorded light intensity at the workpiece ( 8 ) as the first process variable F. Laser processing method according to one of the preceding claims, comprising the process step: - Determining a malfunction of the laser processing machine ( 1 ) based on the modified threshold SOR. Laser processing method according to claim 5, comprising the process step: - Determining a cut-off as a malfunction based on the modified threshold SOR. Laser processing method according to one of the preceding claims, comprising the process step: - Proportional change of at least one threshold value So to the threshold value SOR according to the changed first process parameter F. Laser processing method according to one of the preceding claims, comprising the process step: - Control of the second process variable K as a controlled variable with the manipulated variable being a feed rate of the workpiece ( 8 ) in the laser processing machine ( 1 ) or the power input of the laser processing machine ( 1 ). Laser processing method according to one of the preceding claims, characterized in that the changes of the first process variable F are detected as location-dependent, time-dependent and / or direction-dependent and the at least one threshold value So is changed or set as location-dependent, time-dependent and / or direction-dependent.Laser processing machine (1) with an evaluation device (30), characterized in that the evaluation device (30) is configured to determine at least one threshold value So with respect to a light intensity-dependent first process variable F in at least one working area JQIB or one operating point KAP, to detect a light intensity-independent second process variable K during the operation of a laser processing machine (10) in one working area KAB or one operating point KAP, to determine a change in the first process variable F in the at least one working area KAB or at one operating point KAP under changed process conditions, and to change the at least one threshold value So to a threshold value SQR corresponding to the change in the first process variable F from a value Fo to a value FQR.Laser processing machine ( 1 ) with an evaluation device ( 30 ) according to claim 10 , characterized in that the evaluation device ( 30 ) is designed to . The follow-up length or the inclination angle of a cutting front (29) on a workpiece (8) to be cut is controlled as a second process variable K. A laser processing machine (1) with an evaluation device (30) according to claim 10 or 11, characterized in that the evaluation device (30) is configured to change the at least one threshold value So to the threshold value SOR at the operating point KAP according to a measured light intensity in the working area of ​​a workpiece (8) as a first process variable F. A laser processing machine (1) with an evaluation device (30) according to one of claims 10 to 12, characterized in that the evaluation device (30) is configured to detect a malfunction of the laser processing machine (1) based on the changed threshold value SOR.Laser processing machine (1) with an evaluation unit (30) according to one of claims 10 to 13, characterized in that the evaluation unit (30) is configured to change the at least one threshold value So proportionally to the threshold value SOR according to the changed first process variable F. Computer program product in an evaluation unit. (30) for carrying out the method according to any one of claims 1 - 9.

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