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WO2018219860A1 - Procédé et dispositif pour la surveillance d'un processus d'usinage laser - Google Patents

Procédé et dispositif pour la surveillance d'un processus d'usinage laser Download PDF

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Publication number
WO2018219860A1
WO2018219860A1 PCT/EP2018/063921 EP2018063921W WO2018219860A1 WO 2018219860 A1 WO2018219860 A1 WO 2018219860A1 EP 2018063921 W EP2018063921 W EP 2018063921W WO 2018219860 A1 WO2018219860 A1 WO 2018219860A1
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WO
WIPO (PCT)
Prior art keywords
laser
scattered light
workpiece
detected
scattered
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2018/063921
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German (de)
English (en)
Inventor
Thomas Dünzkofer
Robert Schröder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Messer Cutting Systems GmbH
Original Assignee
Messer Cutting Systems GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Messer Cutting Systems GmbH filed Critical Messer Cutting Systems GmbH
Publication of WO2018219860A1 publication Critical patent/WO2018219860A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/38—Removing material by boring or cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0626—Energy control of the laser beam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/0869—Devices involving movement of the laser head in at least one axial direction
    • B23K26/0876—Devices involving movement of the laser head in at least one axial direction in at least two axial directions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
    • B23K26/127—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in an enclosure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K37/00—Auxiliary devices or processes, not specially adapted for a procedure covered by only one of the other main groups of this subclass
    • B23K37/02—Carriages for supporting the welding or cutting element
    • B23K37/0211—Carriages for supporting the welding or cutting element travelling on a guide member, e.g. rail, track
    • B23K37/0235—Carriages for supporting the welding or cutting element travelling on a guide member, e.g. rail, track the guide member forming part of a portal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N2021/4735—Solid samples, e.g. paper, glass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N2021/8411—Application to online plant, process monitoring

Definitions

  • the present invention relates to a method for monitoring a laser processing process, in particular for puncture detection, wherein a laser beam directed at a workpiece, detected scattered laser light as scattered light, and a change in state of the laser processing process based on the detected scattered light intensity is identified.
  • the present invention relates to a device for monitoring a laser processing process, in particular for puncture detection, with a laser cutting head for focusing a laser beam on a workpiece, with an optical sensor for detecting scattered laser light as scattered light, and with an evaluation and control unit, by means of the Scattered light intensity evaluated and depending on a state change of the laser processing process is identifiable.
  • the laser-assisted thermal cutting of workpieces is generally carried out by combined use of a focused laser beam and a
  • High-power lasers in particular CO 2 , fiber, disc and diode lasers are used, predominantly circularly polarized or unpolarized laser radiation being used in order to avoid a directional dependence in the absorption behavior in contour cuts.
  • the laser beam emitted by the laser beam is guided by means of optics or by means of optical fibers, which are bundled in a fiber cable, to a laser processing head. He is optionally parallelized by a collimator optics and fed to a focusing optics, which the parallel laser beam on the
  • a first hole is produced in the workpiece in a so-called piercing or piercing process.
  • Problematic is the detection of the puncture.
  • the piercing parameters including the typical piercing time are stored in a database for each specific constellation of workpiece type and thickness.
  • the puncturing time must be provided with a time safety buffer which prolongs the total time for processing and unnecessarily introduces further process energy into the workpiece despite the puncturing process actually being completed.
  • These measurement data can also provide information about the quality of the processing and the current state of other characteristic parameters of the laser processing process and can therefore be used for monitoring and controlling the cutting process.
  • further parameters are, for example, the power control during the plunge process, the edge detection, the recognition of a cut-off or plasma formation or the continuity (quality) of the kerf.
  • US Pat. No. 9,427,823 B2 from which an apparatus and a laser processing method according to the aforementioned type are known, for controlling the quality of cut by the laser cutting process detected by the processing point of the workpiece backscattered laser radiation by means of an optical sensor and is evaluated for the control of the cutting process.
  • the measured intensity of the backscattered light is less when the cut passes completely through the workpiece.
  • the frequency or the pressure of gas pulses used in the cutting process are adjusted by means of a control device so that the measured intensity of the backscattered light assumes a minimum value.
  • the optical sensor is housed in a housing mounted laterally on the laser cutting head, which has an opening to the laser beam path, by means of which the backscattered laser light is deflected onto the sensor.
  • optical sensors require a certain amount of space.
  • the sensors are either arranged in the vicinity of the workpiece, so that under cutting conditions they are exposed to high thermal stresses or contamination, for example due to the piercing process, or they are arranged at a considerable distance from the separation process, which leads to an unfavorable signal-to-noise ratio. so that the signal of the sensor usually needs to be amplified.
  • optical sensors have the disadvantage that there are influencing factors in the beam path which change the sensor signal, for example the nozzle diameter.
  • the apertures in the laser processing head must be made larger than otherwise necessary. These devices are complex, delicate and expensive.
  • Engraving hole or the kerf are deeper and less process light or laser radiation reaches the top of the sensor.
  • the invention is therefore based on the object of specifying a method for laser processing that uses scattered laser light to identify the current process state during laser processing, but does not use the above-described invention. reduced parts and ensures a reliable process control, especially for puncture detection.
  • the invention has for its object to provide a simple constructive little expensive and yet reliable device for performing the method.
  • this object is achieved on the basis of a method of the type mentioned in the present invention that scattered light is detected below the workpiece and evaluated to identify the change in state.
  • scattered light is detected below the workpiece to be machined, and optionally below any workpiece support, and the there determined scattered light intensity or its temporal change is used for the identification of a change in state in the laser processing process.
  • the laser light scattered directly on the workpiece is detected, but also, in particular, the laser light which initially passes unaffected a puncture hole, a continuous kerf or a workpiece edge and is then scattered in a working area below the workpiece, for example in a so-called "work table”.
  • a sensor required for detecting the scattered light is not assigned directly to the laser cutting head or integrated therein, so that this measure is also referred to below as "external scattered light detection".
  • the measurement of reflected or scattered laser light takes place above the workpiece and a possible workpiece support.
  • the external stray light detection replaces or supplements the internal stray light detection.
  • measurement and evaluation of reflected or scattered laser light above the workpiece can be done with less equipment. In the replacement case, this effort is completely eliminated.
  • the external scattered light detection can be done by means of a sensor that is not integrated directly into the laser cutting head, this sensor is less subject to the above mentioned limitations and loads in terms of size, measuring distance, pollution and temperature, which can lead to a favorable signal / noise ratio.
  • the measurement result in the external scattered light detection is not subject to a direct influence of guided or reflected laser radiation in the beam path, so that the optics in the laser processing head can be dimensioned comparatively small.
  • the scattered light detection area is below the workpiece.
  • the scattered light is recorded continuously, at regular intervals or as required. In this case, a gradual drift of the scattered light intensity or a rapid change can be detected.
  • a predetermined upper limit is exceeded or when a predetermined lower limit is exceeded (both are also summarized below under the term "threshold value detection")
  • a measured quantity derived therefrom can also be determined or evaluated, such as the temporal change, a mathematical derivation of the temporal course of the intensity signal or the difference between the current intensity signal and a permanently updated, time-averaged intensity value
  • a measured quantity derived therefrom can also be determined or evaluated, such as the temporal change, a mathematical derivation of the temporal course of the intensity signal or the difference between the current intensity signal and a permanently updated, time-averaged intensity value
  • the laser processing process according to the invention is, for example, the process phase for producing a puncture in the workpiece to be machined.
  • the generated puncture results in the state change to be identified.
  • the energy input into the puncture crater is changed or stopped.
  • the detected change of state can lead to an operator message in order to visually or acoustically display the changed conditions to the operating personnel so that a manual interpretation can be intervened in case of a misinterpretation.
  • the actual laser cutting process begins, in which the movement direction and / or the movement speed of the laser cutting head relative to the workpiece surface and the laser Energy and gas parameters are adapted to the cutting process.
  • the evaluation signal thus obtained has a good signal-to-noise ratio, which also makes it possible, for example, to detect a puncture at an early stage, preferably even in its formation.
  • the method according to the invention can also be used without restriction for workpieces having larger material thicknesses of, for example, more than 10 mm.
  • the method according to the invention can also be advantageously used for other phases of the laser processing process in which there is a gradual and in particular a sudden change of the scattered light in the area below the workpiece to be machined.
  • the detection of a cut-off or the detection of material edges may be mentioned.
  • the demolition of the cutting beam is the state change to be identified, and in the latter case, it is the positioning of the scanning laser beam for edge detection outside the workpiece contour.
  • the detection of the scattered light in the region below the workpiece to be machined by means of a scattered light detection device or by means of multiple scattered light detection devices.
  • Each of the detection devices is equipped with at least one photosensitive optical sensor.
  • the scattered light can impinge directly on the sensor when it is arranged in the detection region for the scattered laser light below the workpiece to be machined.
  • the scattered light can also be transmitted via optical guiding means, such as an optical fiber, an optical fiber cable or imaging optics, to a sensor, which may optionally be arranged inside or outside the detection area.
  • optical guiding means such as an optical fiber, an optical fiber cable or imaging optics
  • the scattered below the workpiece support laser light is detected by at least one optically largely shielded detection device. That is, the scattered light detecting means is largely optically shielded in the stray light detection area, for example, by being housed in a chamber having only a single light opening to the stray light detection area.
  • the scattered light intensity is detected in a wavelength range which comprises the wavelength ⁇ of the laser beam narrow band, preferably in the band range between ⁇ +/- 100 nm.
  • the photosensitive element of the optical sensor is such that its maximum sensitivity lies within the wavelength range in which the expected wavelength of the scattered light lies. This corresponds essentially to the wavelength ⁇ of the working radiation of the laser.
  • the scattered light detection device is equipped with an optical filter which is transparent to radiation having a wavelength ⁇ of the working radiation of the laser and substantially blocks radiation of other wavelength ranges.
  • the at least one scattered light detection device is arranged stationary or movable in the scattered light detection range. In the case of a fixed arrangement, preferably a plurality of scattered light detection devices are distributed in the scattered light detection area. In a particularly preferred variant of the method, at least one detection device for the scattered light is tracked along a movement axis of the laser beam.
  • the laser beam is generated by means of a laser cutting head, which is moved by means of a machine portal, and wherein the at least one detection device is moved synchronously to the movement of the machine portal.
  • the detection device is mounted for this purpose, for example, on the machine portal. Due to the uniaxial, reversing tracking of the scattered light detection device, the distance between the laser beam and the detection device can be kept as low as possible. This ensures that the detected scattered light intensity is influenced as little as possible by this distance.
  • the method according to the invention is also particularly well-suited for a phase of the laser processing process referred to as "edge detection.”
  • the laser beam is generated by means of a laser cutting head, which is moved by means of a machine portal, and wherein the laser processing process comprises a process phase of detection of a workpiece edge.
  • edge detection or edge detection the laser beam is moved over a workpiece edge.
  • the movement is essentially perpendicular to the edge of the workpiece.
  • work is done with the lowest possible effective laser power.
  • the low effective power is still well recognized by the scattered light detection device.
  • the rise or fall of the measurement signal shows according to the correlating machine coordinate, the position of the workpiece edge and thus, when measuring several points, the position and position of the workpiece.
  • the method according to the invention is particularly well suited for a phase of the laser processing process in which the quality of the kerf generated by the laser beam and any disruption of the laser beam is monitored.
  • the laser beam is generated by means of a laser cutting head, which is moved along a predetermined cutting contour and thereby in the sectional contour of a
  • the laser processing process comprises a process phase, during which the movement speed and / or the energy input is adjusted in the kerf in dependence on the detected stray light intensity.
  • the manipulated variable of the process control in this phase of the laser processing process is thus the movement speed, laser power, focus position, distance stood between laser head and workpiece, the gas pressure and / or the energy input into the kerf depending on the detected scattered light intensity.
  • the laser cutting process is stopped and a message is issued.
  • the cutting contour can also be repeatedly overrun at the position of the cut-off, or the speed is reduced for a short time.
  • the abovementioned object is achieved on the basis of a device of the type mentioned in the introduction by providing at least one optical device for detecting stray light below the workpiece, which is connected to the evaluation and control unit.
  • the device according to the invention is designed for "external scattered light detection", as described above with reference to the method according to the invention,
  • the device is particularly well suited for carrying out this method.
  • the scattered light is detected below the workpiece or below a workpiece support, and the scattered light intensity determined there or its temporal change or a measured variable correlated therewith is transmitted to the evaluation and control unit. Based on the scattered light intensity measurement, a state change of the laser processing process is identified continuously, at regular intervals or as needed.
  • the external stray light detection replaces or supplements the internal stray light detection.
  • measurement and evaluation of reflected or scattered laser light above the workpiece can be done with less equipment. In the replacement case, this effort is completely eliminated.
  • the external stray-light detection can be done by means of a sensor that is not directly integrated into the laser cutting head, this sensor is less subject to the above-mentioned restrictions and loads in terms of size, measurement distance, contamination and temperature, which can lead to a favorable signal / noise ratio.
  • the measurement result in the external scattered light detection is not a direct influence of guided or reflected laser radiation in the beam path, so that the optics in the laser processing head can be dimensioned comparatively small.
  • the scattered light detection area is generally below a workpiece support, for example a so-called cutting grid. In this case, a gradual drift of the scattered light intensity or a rapid change can be detected. In both cases, when a predetermined upper limit is exceeded or when a predetermined lower limit is exceeded, it is assumed that a certain change in a process state correlated with the scattered light intensity has occurred.
  • control unit may respond thereto by changing a parameter or storing a characteristic parameter value, such as the detected position value of a workpiece edge.
  • the energy input into the puncture crater is changed or stopped or the movement direction and / or the movement speed of the laser cutting head relative to the workpiece surface are changed.
  • the energy input into the puncture crater is changed, for example, by changing the focus position, pulse frequency, power and / or pulse duty factor of the laser. Since scattered light can only penetrate the workpiece after a puncture has taken place, a rapid increase in the scattered light intensity in the area below the workpiece is possibly detected, so that a clear, reproducible relationship between the measured course of the scattered light intensity and the puncture is given.
  • the evaluation signal thus obtained has a good signal-to-noise ratio, which also makes it possible, for example, to detect a puncture at an early stage, preferably even in its formation.
  • the temporal change in the scattered light intensity when the puncture is carried out is almost independent of the type of material and the workpiece thickness, so that the device according to the invention can also be used without restriction for cutting workpieces having larger material thicknesses of, for example, more than 10 mm.
  • the device according to the invention can also be used advantageously for other phases of the laser processing process, in which there is a gradual and in particular a sudden change in the scattered light in the area below the workpiece to be machined can come.
  • the detection of a cut-off or the detection of material edges may be mentioned.
  • the detection of the scattered light in the region below the workpiece to be machined by means of a scattered light detection device or by means of multiple scattered light detection devices.
  • Each of the detectors is equipped with at least one photosensitive optical sensor.
  • the scattered light can impinge directly on the sensor when it is arranged in the detection region for the scattered laser light below the workpiece to be machined.
  • the scattered light can also be transmitted via optical guiding means, such as a fiber optic cable, an optical fiber cable or imaging optics, to a sensor, which may optionally be arranged inside or outside the detection area.
  • the scattered light detection device is that component which is arranged in the scattered light detection region and on which the scattered light impinges directly.
  • the following embodiments have proved successful, which can be implemented individually or preferably in any desired combination with one another:
  • At least one optically extensively shielded detection device is preferably provided.
  • the scattered light detecting means is largely optically shielded in the scattered light detection area, for example, by being housed in a chamber having only a single light opening to the scattered light detection area.
  • the scattered light detection device is designed to detect the scattered light intensity in a wavelength range which comprises the wavelength ⁇ of the laser radiation narrow band, preferably in the band range between ⁇ +/- 100 nm.
  • the photosensitive element of the optical sensor is such that its maximum sensitivity is within the wavelength range in which the expected wavelength of the scattered light is located. This corresponds essentially to the wavelength ⁇ of the working radiation of the laser.
  • the scattered light detection device is equipped with an optical filter which is transparent to radiation having a wavelength ⁇ of the working radiation of the laser and substantially blocks radiation of other wavelength ranges.
  • the device according to the invention enables, for example, early and reliable detection of the imminent or completed puncture, the locating of a workpiece edge and the detection of a so-called cut-off, ie a suspension of the laser beam.
  • Figure 1 shows a construction diagram of a device according to the invention for puncture detection in a schematic representation
  • FIG. 2 shows an embodiment of a scattered light sensor for use in the device according to the invention in a schematic representation
  • Figure 3 is a schematic of a laser processing machine with moving unit and cutting table in a plan view
  • FIG. 4 shows a diagram for explaining the puncture recognition and the subsequently continued laser cutting process in a sectional contour with inner section and outer section on the basis of the time profile of the measured scattered light intensity
  • FIG. 5 shows a diagram for explaining the reproducibility of the puncture recognition in the case of a narrow workpiece strip on the basis of the time profile of the measured scattered light intensity in five consecutive puncture attempts
  • 6 shows a diagram for explaining the reproducibility of the puncture detection when using sensors in different areas of a cutting trough on the basis of the time course of the measured scattered light intensity in a puncture test
  • 7 shows a diagram with signal responses during the puncture with different laser beam parameters on the basis of the time profile of the measured scattered light intensity in a plurality of puncture attempts.
  • the puncture recognition device 1 shown schematically in FIG. 1 is part of a laser cutting machine and is used in the thermal processing of a workpiece 2 for monitoring a puncturing operation in the workpiece 2 and for driving the laser cutting machine during the puncturing operation.
  • the laser cutting machine comprises a laser processing unit which can be moved in all directions in space (shown schematically in FIG. 3)
  • a laser cutting head (FIG. 3, reference numerals 4 and 5) by means of which a laser beam 3 is focused on the workpiece 2 via a collimator and a focusing lens 4 and a cutting nozzle 5.
  • the workpiece 2 rests on a cutting grid 7 and this on a cutting trough 8.
  • the cutting tray space below the workpiece 2 is designated by the reference numeral 10.
  • the laser In the case of the laser,
  • the laser beam has a working wavelength of about 1070 nm.
  • a machine control 6 20 is provided. With the machine control unit 6, a plurality of scattered-light sensors 9 are connected, which are mounted at a distance of 100 cm in a stationary manner inside the cutting-tub interior 1 1 below the cutting grid 7. The scattered light sensors 9 are used to measure scattered radiation 10, which in the laser cutting process due to different events in the cutting tub interior
  • FIG. 2 schematically shows such a scattered light sensor 9 in a longitudinal section.
  • a metal tube 21 In the inner bore of a metal tube 21 are starting from a
  • a protective glass 23 against the ingress of dust into the inner bore an optical filter 24 for passage of infrared radiation in Wel- lenanz Scheme from 1050 to 1 1 10 nm and a photosensitive member 25 having a main absorption wavelength in this wavelength range, which is connected to an evaluation of the machine control 6.
  • FIG. 3 shows that the laser cutting head (4, 5) is mounted on a machine portal 31.
  • the machine portal 31 is mounted on guide rails 32 along which it can be moved longitudinally in the x-direction (directional arrow 33).
  • the laser cutting head (4; 5) itself can be reversibly moved back and forth reversibly on the machine gantry 31 along a y-axis of movement (directional arrow 34).
  • the cutting trough 8, which is divided into a plurality of spatially separated segments 38 extends.
  • Either a scattered light sensor 9 is arranged in each of the segments 38, or alternatively (as in the embodiment of the device according to the invention shown in FIG. 3), a scattered light sensor 39 is provided which is mounted on the machine gantry 31.
  • This stray light sensor 39 performs the same longitudinal movements along the x-movement axis as the machine gantry 31 and the laser cutting head (4; 5).
  • the scattered light sensor 39 is thus always in synchronism with the laser cutting head (4, 5), both in terms of the longitudinal position and the movement speed of the longitudinal movement of the laser cutting head (4, 5); it receives the scattered laser radiation from the cutting trough interior 1 1 from each of the laser cutting head attacked segment 38. Therefore, sufficient in this embodiment, a single scattered light sensor 39 for detecting the scattered light.
  • Figure 4 shows the time course of the measured scattered light intensity when cutting a square with an internal bore of a workpiece made of 15 mm thick structural steel. About 4 seconds after the start of the piercing operation 40 results in a rapid increase in the scattered light intensity 41, which was a successful
  • Punctuation indicates.
  • the measuring signal of the scattered light intensity A is raised approximately to a higher level, and remains with the laser beam on this- sem level 41. After the puncture, the laser beam is switched off for a short time and the signal of the scattered light intensity A falls off.
  • FIG. 5 shows the scattered light intensity profile in the case of five consecutive puncture tests in the workpiece strip. An influence of interfering radiation is not recognizable.
  • the outlier 51 at one of the averages is due to an explosive ejection of the workpiece material due to a workpiece fault or non-optimal piercing parameters.
  • FIG. 6 shows the scattered light intensity profile in the case of a triple-bridged puncture test, wherein the scattered light intensity signal has been evaluated by a sensor 9 which is located in a segment 38 (see FIG. 6
  • Cutting trough 8 is located, which is not directly below the cutting position, but in a neighboring segment. Although the respective segments are optically largely shielded by sheets and Insofar as separate chambers form within the cutting trough 8, a similar scattered light intensity signal arises in all of the puncture tests, which speaks for the reproducibility of the method.
  • the elevations in the intensity signal in the grooves 2 and 3 are due to an explosive slag ejection due to a non-optimal puncture.
  • the diagram of FIG. 7 shows the result of a further preliminary experiment in which the laser pulse frequency is set to 10 Hz, 50 Hz and 100 Hz in three steps, and then the duty cycle (pulse duration / period duration) of the laser parameters is also set in three steps of 10% and 30 % has been increased to 50%.
  • the duty cycle pulse duration / period duration

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  • Laser Beam Processing (AREA)

Abstract

L'invention concerne un procédé connu de surveillance d'un processus d'usinage laser, selon lequel un faisceau laser est dirigé sur une pièce, la lumière laser diffusée est détectée en tant que lumière diffusée, et une modification d'état du processus d'usinage laser est identifiée sur la base de l'intensité de la lumière diffusée détectée. L'objet de l'invention est de mettre au point, sur cette base, un procédé d'usinage laser, lequel utilise un rayonnement laser diffusé pour identifier l'état de processus actuel lors de l'usinage laser, et lequel garantit un contrôle fiable du processus, en particulier pour repérer une perforation. À cet effet, selon l'invention, la lumière diffusée est détectée au-dessous de la pièce et évaluée pour identifier la modification d'état.
PCT/EP2018/063921 2017-05-30 2018-05-28 Procédé et dispositif pour la surveillance d'un processus d'usinage laser Ceased WO2018219860A1 (fr)

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DE102017115486.8A DE102017115486B4 (de) 2017-05-30 2017-07-11 Verfahren und Vorrichtung zur Überwachung eines Laserbearbeitungsprozesses

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US20230132812A1 (en) * 2021-10-29 2023-05-04 Samsung Display Co.,Ltd Laser processing apparatus and laser processing method using the same
CN116209536A (zh) * 2021-09-27 2023-06-02 国立大学法人东海国立大学机构 加工装置和加工完成检测方法
CN117295579A (zh) * 2021-03-11 2023-12-26 通快机床欧洲股份公司 用于识别加工过程中的干扰的方法以及加工机

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JP6968126B2 (ja) * 2019-06-26 2021-11-17 株式会社アマダ レーザ加工機の設定方法及びレーザ加工機
DE102019127900B3 (de) * 2019-10-16 2021-04-01 Precitec Gmbh & Co. Kg Verfahren zur Überwachung eines Laserbearbeitungsprozesses zur Bearbeitung von Werkstücken
DE102020209589A1 (de) 2020-07-30 2022-02-03 Trumpf Werkzeugmaschinen Gmbh + Co. Kg Verfahren und Vorrichtung zum Erkennen eines Fehlschnitts beim trennenden Bearbeiten eines Werkstücks
DE102021108496A1 (de) 2021-04-06 2022-10-06 Trumpf Laser- Und Systemtechnik Gmbh Vorrichtung und Verfahren zur Ermittlung einer Standzeit eines Werkstückprüflings bei Laserbestrahlung
DE102023134846A1 (de) 2023-12-12 2025-06-12 TRUMPF Werkzeugmaschinen SE + Co. KG Verfahren zum Einbringen von Trennschnitten in tafelförmige Werkstücke

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US20230132812A1 (en) * 2021-10-29 2023-05-04 Samsung Display Co.,Ltd Laser processing apparatus and laser processing method using the same

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