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
  • B23K26/02—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
  • B23K26/044—Seam tracking
• • 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

Definitions

• the present invention relates to a method for adjusting at least one technology parameter of a laser processing, in particular a laser welding process. Furthermore, the invention relates to a machine tool for laser processing with various technologies, in particular laser welding processes.
• Exemplary methods in laser welding (LSW) technology include i.a. the "pure" LSW, the LSW with wire, the LSW with wire and ring focus, etc. Each of these methods provides for certain to be welded processing situations that z. B. by the impact situation, the material, the available laser radiation and the present to be bridged gap determined closer, a preferred LSW process.
• an LSW process is defined by specific technology parameters.
• the selection of the method to be used for the LSW technology and in particular the associated technology parameters is usually based on empirical values and rudimentary tables.
• the latter include exemplary joining geometries, sheet metal strengths and machining materials. Different joining geometries, in particular joints, are described for example in DIN EN ISO 17659.
• One aspect of this disclosure is based on the task of supporting the determination of a processing process for a specific processing situation from the group of possible processing methods, for example selecting in particular a best possible LSW method for an LSW process to be performed.
• At least one of these objects is achieved by a method for adjusting at least one technology parameter of a laser processing according to claim 1 and by a machine tool according to claim 8. Further developments are specified in the subclaims.
• an operator is provided with an image-based support function by which he selects the corresponding processing method for the specific processing process.
• the image-based support function allows z. For example, a preselected and optimized selection of one or more LSW methods for a LSW process. In this case, for example, a sensor, as z. B.
• routines such as the routine "TeachLine” Applicant is used to measure a gap to be welded and based on the result of a correct, ie the processing situation in the sense of the operator best corresponding, LSW method for to provide the LSW process with the appropriate technology parameters.
• the step of providing the image-based support function includes overlaying the acquired image information of the processing situation with assisting visual information.
• the processing situation can be overlaid with supporting visual information on the workpiece become.
• the visual information includes, for example, distance markings, such as one or more distance circles and / or a target cross. These can be added to the image data by means of data processing.
• markings, in particular distance markings can be projected onto the processing situation by means of light, so that the acquired image information of the processing situation includes the visual information and a generation of the mark-extended image data record takes place directly.
• the distance markings may be dependent on input variables of the laser processing, in particular the beam source and / or the maximum available laser power, and / or the workpiece, in particular the material type and / or the material thickness, and / or the joining geometry, such as butt joint, T-joint or corner joint, selected and in particular adapted in their representation, for example, scaled, represented.
• the step of providing the image-based support function includes detecting joining geometry parameters, such as gap width, material step height, and / or impact angle, by image processing the mark-extended image data set, and / or providing an input interface to a user to enter joining geometry parameters , such as gap width, material grade and / or impact angle, based on a representation of the mark-extended image data set.
• joining geometry parameters such as gap width, material step height, and / or impact angle
• the method may comprise outputting the mark-extended image data record on a display device as an auxiliary display.
• the method may include one or more of the following steps:
• laser processing parameters such as laser power, focus position, focus shape (eg. Point or ring focus) and / or focus diameter
• joining geometry parameters such as joint type and / or gap
• workpiece parameters such as material type and / or material thickness
• protective gas insert such as protective gas type, welding wire insert, welding wire feed and / or welding wire type.
• a machine tool comprises a laser processing system having a laser beam source and a laser processing head, wherein the laser processing head is optically connected to the laser beam source, and a workpiece holder, wherein a relative movement between the laser processing head and the workpiece holder for performing a laser processing is effected.
• the machine tool comprises an imaging sensor system for optically acquiring image information of a processing situation of the laser processing to be performed, wherein the imaging sensor system is arranged in particular on or in the laser processing head, and a control unit for carrying out the methods disclosed herein for setting at least one technology parameter of a laser processing.
• control unit is configured to generate a mark-extended image data set of the processing situation based on the image information, and optionally for image processing of the mark-extended image data set for obtaining technology-relevant parameters.
• control unit a memory unit for providing a technology database with technology parameters for laser processing by means of z. B. laser welding processes.
• the technology database can, for a multitude of laser processing Technologies include: laser processing parameters such as laser power, focus position, focus shape (eg point or ring focus) and / or focus diameter, joining geometry parameters such as joint size and / or gap dimension, workpiece parameters such as material type and / or material thickness, machining material, and supporting parameters such as welding wire insert, welding wire feed and / or welding wire type, protective gas insert and / or protective gas type.
• control unit may be designed to read out and provide a proposal for one or more laser processing technologies from the technology database based on detected technology-relevant parameters.
• the machine tool can have an input device for entering marking parameters and / or a display device for displaying image data records, in particular the mark-extended image data record.
• the concepts disclosed herein may in particular have the advantage that separate and z.
• hand-held meters such as calipers, dial gauges
• FIG. 1 shows a schematic three-dimensional representation of a machine tool for robot-guided welding
• FIG. 2 shows a schematic representation to clarify the acquisition of image information of a processing situation
• FIG. 3 is a schematic representation of a workpiece onto which a distance mark has been projected
• FIG. 4 shows a schematic illustration of a further processing situation
• FIGS. 5A-5C show schematic illustrations for clarifying the detection of impact configurations with a line beam
• FIGS. 5A-5C show schematic illustrations for clarifying the detection of impact configurations with a line beam
• 6 is an exemplary flowchart to illustrate a method for
• At least one technology parameter of a laser processing is based, in part, on the recognition that sensor systems can be used for manual, semi-automated or fully-automated selection of technology parameters, in particular welding parameters and specific LSW methods. Often, it is possible to use existing hardware such as observation optics, marking lasers etc. to support the technology selection. In particular, it has been recognized that an image-based support function may generate a mark-extended image data set in response to at least one input provided to support the selection of the technology parameters.
• the at least one provided input variable may include an input of the system, such as beam source and / or maximum power, and / or an input of the workpiece, such as material, sheet thickness and / or joining geometry (butt joint, T-joint, corner joint). It has also been recognized that, for example, a marking underlying a mark-extended image data record can be selected as a function of the input variable from a group of possible markings and in particular adapted, for example scaled, in terms of its representation.
• FIG. 1 an exemplary laser processing machine tool will be described in conjunction with FIG. 1, in which the concepts disclosed herein may be used to assist in the adjustment of laser processing technology parameters. Subsequently, with reference to the schematic representations of FIGS. 2 to 5C and to the flowchart of FIG. 6, possible implementations of the concepts when setting technology parameters of a laser processing will be clarified.
• FIG. 1 shows a machine tool 1 with a laser processing system 3 for the machining of a workpiece 5.
• a control panel not explicitly shown
• workflows machining processes
• the machine tool 1 has a control cabinet with the control system 7, in which an associated CNC control, an electrical supply of drives and generally logic and power parts are provided.
• the laser processing system 3 provides laser radiation with usually partially adjustable and partially fixed laser beam parameters for a selected processing ready for action. For example, it may be based on a solid-state laser such as a disk laser or fiber laser or a gas laser such as a CO 2 laser as the laser beam source 3A.
• a beam guidance from the laser beam source 3A to a machining head 3C can take place via laser light cables 3B and / or mirrors.
• the processing head 3C focuses the laser light onto the workpiece 5.
• the laser processing system 3 provides a working zone in which, for B. a welding process can be performed.
• the laser processing system 3 can be adjusted for a machining process in various laser processing parameters, such as laser power, focus position, focus shape (eg point or ring focus) and / or focus diameter.
• the laser processing system 3 can also z. B. a welding wire device with u. a. a welding wire supply 3D and a welding wire nozzle 3E and / or a protective gas device with u. a. a protective gas supply 3F and a protective gas nozzle 3G have.
• the laser processing system 3 can be set in various supporting parameters, such as protective gas insert, protective gas type, welding wire insert, welding wire feed and / or welding wire type.
• the laser processing system 3 may further in various workpiece parameters, such as material type and / or material thickness, and z. B. in welding operations in different joining geometry parameters, such as joint and / or gap, can be adjusted.
• the laser machining system 3 can also be set in various motion parameters, such as position and (travel or relative) speed of the workpiece 5 and / or of the machining head 3C.
• These various technology parameters and movement parameters can be stored in a memory unit of the control system 7 z.
• a controlled by the CNC control workflow allows the machining of the workpiece 5 in a predetermined manner with cooperation of the various components of the laser processing system 3.
• the workflow may include a plurality of different, alternating machining processes. These are usually defined within a teach-in process to define a laser processing to be performed. A sequence of operations can be performed repeatedly one after the other, and thus process a large number of workpieces efficiently and substantially the same - despite any variation in the dimensions due to tolerance ranges.
• a programmer creates the NC program for the respective production order within a programming system on the computer, ie, for example, at the control console 7.
• the path of the laser focus can be calculated by the control system 7 automatically or under the influence of the operator.
• the control system 7 may specify the processing sequence, for. B. Set start and end points to the right places.
• the control system 7 can implement the strategies and technologies that an operator selects workpiece-specific, ie for a processing situation. In a preparatory simulation, the operator can see how the NC program is processed.
• the NC program provides the appropriate values for the aforementioned technology parameters, such as
• Travel speed, laser power, focus size and distance are read from the technology table that the controller can access.
• the technology parameters include workpiece-specific parameters such as tolerance limits of (eg sheet metal) edges and maximum possible movement speeds of the machining head 3C relative to the workpiece 5.
• FIG. 1 also schematically shows an exemplary robot-based structure of the laser processing system 3, in which the machining head 3C is fastened to a robot arm 9A of a robot 9.
• the robot 9 can have a movement unit with function-relevant components, such as slides, telescopic arms, and rotational joints, for moving the machining head 3C relative to the workpiece 5.
• the laser machining be provided on an XYZ Cartesian machine and / or the workpiece to be positioned with a robot.
• the alignment of the machining head 3C to the workpiece 5 is effected by the rotating and pivoting axes which define the specific working space comprising all the points which can be processed by the correspondingly focused emerging laser beam.
• the workpiece 5 can be mounted fixedly on a workpiece mounting device with a clamping technique (in FIG. 1, a workpiece support 11 is indicated schematically).
• a workpiece support 11 is indicated schematically.
• the workpiece / workpiece storage device or only the workpiece / workpiece storage device is movable in space, for example by means of another robot arm.
• the concepts disclosed herein may be adapted as appropriate in such configurations as well.
• the laser beam exits via a nozzle, for example, together with a protective gas from the processing head 3 C.
• an optical system 13 (not shown in detail) is provided.
• the machining head 3C can be positioned and aligned essentially freely in space, for example by rotating and pivoting axes of the robot arm 9A, and thus guide the exiting laser beam in a targeted manner over the workpiece 5, the optical system 13 making it possible to image the focus area.
• the optical system 13 includes, inter alia, a camera system which is designed for optical acquisition of image information of a processing situation of a laser processing.
• the image information can z. B. coaxial with the (processing) laser beam or laterally, for example, be obtained at an adjustable angle.
• the optical system 13 may further comprise a marking system for superimposing an optical mark on the focal region of the workpiece 5 imaged by the camera.
• a marking of the region of the workpiece 5 imaged by the camera system can take place in a subsequent image processing.
• the image-based technology selection for LSW processes disclosed herein generally employs laser welding optics which, as previously explained, can be implemented by means of a robot or a Cartesian
• Positioning machine can be positioned on a spot to be welded.
• the laser welding optics for guiding the laser beam can acquire image information about the basic conditions of the machining situation underlying the welding process, for example coaxially with the (processing) laser beam or laterally in the direction of a joint.
• machining situations include, for example, a butt joint (FIG. 2), a lap joint (FIG. 4) or other butt configurations such as a 90 ° corner joint (FIG. 5C), a T joint, etc.
• the optical system 13 may provide information for automatic or manual evaluation of the machining situations.
• An automatic evaluation is based z. B. on image processing of the underlying image data sets.
• a pattern (or more patterns) z. B. in the form of coaxial circles (for example, similar to a target) superimposed, which is then displayed on a screen of a display device 15 for LSW care.
• a projection of patterns z. B. with the help of visible laser lines directly on the workpiece is also considered.
• FIG. 2 shows, by way of example, a machining situation 21 of a butt joint of two workpiece plates 5A, 5B, which are separated by a gap 23 prior to machining and are to be welded together along the gap 23.
• the display device 15 On the screen of the display device 15 can be seen an enlarged image of the processing situation 21 with the workpiece plates 5A, 5B and the gap 23. Furthermore, one recognizes a superimposed pattern, which is shown as a distance mark 25, in particular with distance circles 25A and a target cross 25B on the screen becomes.
• the distance marks 25 were from the control system 7 z. B. for a captured image information of the processing situation 21 calculated (and / or adapted) and are part of a marker-extended image data set 27, which in addition to the originally captured image information includes the marker.
• Another image processing of the mark-extended image data set 27 can For example, calculate the technology parameter gap width d or an operator determines a gap width d (in the x direction) based on the representation of the marker-enhanced image data set 27.
• the patterns can also be a measurement function, as z. B. from CAD systems, are used.
• the position of joint-characterizing features, such as the gap width d, relative to these patterns represents a selection criterion for a suitably applicable LSW technology and the associated technology data (process and / or control data).
• the gap width d between two characterizing points can be determined by manual or automatic marking of the mark-extended image data set 27 displayed on the screen and incorporated directly into the selection of technology (LSW method) including technology parameters.
• the diameter of the displayed or superimposed coaxial circles can be made dependent on which input variable (s) of the LS W system (beam source, maximum power, etc.) and the workpiece, such. B. material, plate thickness and joining geometry (butt joint, T-joint, corner joint, etc.) was provided (s).
• input variable (s) of the LS W system beam source, maximum power, etc.
• material, plate thickness and joining geometry butt joint, T-joint, corner joint, etc.
• different limits can be provided between the optimum parameter sets of different laser processing technologies, and depending on the input variable (s), the auxiliary display of the marking (s) can be adapted accordingly.
• the parameters of the parameter sets for a laser processing technology can, for. B. include: laser power, feed rate, focus position, focus shape (eg point or ring focus), focus diameter, welding wire and welding wire feed.
• an input quantity refers to the machine tool and / or the workpiece provided for the laser processing.
• this is usually also a parameter from the parameter sets of the possible laser processing technologies.
• the coaxial circles show, for example, the boundaries between the parameter sets z. B. depending on the gap width d.
• the parameter set of the innermost circle may include a point focus and no welding wire insert, the parameter set of the circle around it, for example, a ring focus and a welding wire insert with a low welding wire feed, and the parameter set of around the two inner circles
• the circuit included the use of a ring focus and a welding wire insert with higher welding wire feed.
• the parameter sets may also contain further of the above-mentioned parameters.
• Fig. 3 shows a plan view of the processing situation 21 of Fig. 2, wherein supporting visual information is projected onto the workpiece plates 5A, 5B.
• the distance marking 25 ' is projected onto the processing situation by means of light, so that the acquired image information of the processing situation 21 also includes the visual information, here the distance mark 25'.
• the setting of certain parameters can, for. B. carried out analogously to the procedure described in connection with FIG.
• FIG. 4 shows a plan view of a further processing situation 2, in which two workpiece plates 33A, 33B are to be welded along a parallel joint.
• a marking source 35 generates, for example, a line beam 37, which propagates over the forming step with height difference ⁇ . Due to different path lengths z1, z2 except for the respective surfaces of the workpiece plates 33A, 33B, the height difference ⁇ can be determined, for example, by an offset upon irradiation of the line beam at an angle with respect to the surfaces.
• FIGS. 5A-5C illustrate further examples of how impact configurations can be detected by means of markings (here by way of example with a line beam).
• 5A generally shows, in a sectional view, the illumination of a workpiece 5 with a line beam 41 (view in the direction of the line), the line beam 41 being irradiated at an angle of less than 90 ° with respect to the surface of the workpiece 5.
• the workpiece 5 comprises two in-plane workpiece plates 45A and 45B. If these extend, in particular their surfaces, in one plane, two partial laser lines 45 A ', 45 B' are formed on the plates 45A and 45B detectable, which are indicated in Fig. 5B as dashed laser lines for clarity added. Due to the extension of the workpiece plates 45A and 45B in a plane, the detected partial laser lines 45A ', 45B' contained in the mark-extended image data set merge linearly on the plates 45A and 45B shown.
• a corner joint is shown in Fig. 5C as a machining situation 21 ", in which the two workpiece plates 45A, 53B are to be welded at an angle to each other.
• two partial laser lines result 45A “, 45B” on the plates 45A and 45B, again shown in phantom for clarity in Fig. 5C.
• the partial laser lines 45A ", 45B This angle makes it possible to determine the angle between the workpiece plates 45A, 45B as a technology parameter, by means of which a suitable laser processing process can then be determined.
• the processing optics are guided along the weld to be welded during a teach-in process.
• the operator uses a robot control to set the sequence of movements to be programmed.
• z. B the position of the processing optics stored in the controller. That is, it is noted for each intermediate position, with which motion parameters this point is to be approached later.
• a data record is stored which may include, among other things, all joint coordinates or position and orientation of the laser processing head, stopping or smoothing, the speed and the acceleration.
• the robot moves in sequence all stored intermediate positions and thus works off the intended sequence of movements.
• the processing takes place with a respectively applicable parameter set of the laser processing.
• the laser processing to be carried out subsequently can be defined by means of the assistance function disclosed herein.
• at least one input variable of the laser processing is initially provided (step 51), eg. B. manually entered by a teacher performing the teach-in.
• the at least one input variable is, for example, an input variable of a machine tool provided for the laser processing and / or an input variable of the workpiece.
• the machine tool may have an optical sensor system for detecting the position of the workpieces and welds, the z. B. can also be used for teach-in programming.
• the sensor system may also measure the position of the workpiece or joint during the machining process and adjust the position of the robot to the position of the workpiece.
• the optical sensor system comprises z. As a mostly high-resolution CCD camera that can take pictures especially at the intermediate positions.
• the optical sensor system can also be used for acquiring image information of the processing situation of a laser processing (step 53). Based on the acquired image information and in dependence on the at least one input variable of the laser processing, a mark-extended image data set is generated (step 55).
• the generated marker-extended image data set can be visually evaluated by the machine operator in another. Alternatively or additionally, an automated evaluation can take place within the scope of an image processing system.
• Image data set may allow, for. B. position and position of the workpiece and the joint to measure at an intermediate position, such. B. to determine the presence of a fillet weld, flanged seam, I-seam, lap seam or corner seam. They allow such. B. also checking the present gap and the gap profile. This requires, for example, a corresponding use and a specific control of additional material (eg welding wire), which should be part of the laser processing to be determined.
• additional material eg welding wire
• the generation of the mark-extended image data record 27 can include, in particular, that supporting visual information, in particular markings (eg one or more Distance circles, a target cross, etc.) is included as additional image information in the image information acquired in step 53 (step 55A in Fig. 6) and thus provided with the image-based support function.
• the generation of the mark-extended image data record 27 may further include optically superimposing visual information supporting the processing situation (step 55B in FIG. 6) and thus already included in the acquired image information from step 53. For example, markings (eg distance markings analogous to above) or special light patterns are irradiated onto the machining situation (for example, a laser line is projected onto the workpiece to be welded).
• an illumination system can be integrated in the optical sensor system, which illuminates the measurement surface with the marking, such as distance markings, z. B. one or more distance circles and / or a target cross, or a special light pattern, such as a laser line allows.
• the additional visual information is selected from a group of types of additional information, e.g. B. Types of distance markers, selected and adapted in their representation depending on the provided input size (step 57A).
• image information of a processing situation is recorded by means of an optical sensor system.
• this additional information is acquired directly with the image data as a mark-extended image data record 27.
• the mark-extended image data set 27, in which the acquired image information of the processing situation and the auxiliary information are superposed, is output on a display (step 59).
• the picture information can be On the processing situation 21 and / or the mark-extended image data set 27, for example by the evaluation of a projected laser line, an adaptation of the diameters of circles of a circular pattern are made.
• a machine operator can use the illustrated mark-extended image data set and enter via a provided input interface a visually recognized joining geometry parameter, such as gap width, material level and / or impact angle. As a result, the marking and thus the mark-extended image data set can be renewed again.
• the marker-enhanced image data set 27 can generally be used to detect technology parameters of laser processing, such as laser processing. As the shock type and / or the impact angle, are used. Thus, the marker-extended image data set can be used to determine the machining process (step 61). For example, a technology database is provided (step 61A) and a technology parameter is selected from the database using the marker-extended image data set 27 (step 61B). Moreover, the machine operator can be given one or more suitable laser processing methods depending on the selected technology parameter (step 6 IC). Based on the laser processing method proposed in this way, the machine operator can specify the laser processing with the correspondingly selected machining processes (step 63). Together with the teach-in, this results in a comprehensive planning of the control of the machine tool for performing a laser processing, which can be carried out efficiently in particular with the embodiments of the image-based assistance function disclosed herein.

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• Engineering & Computer Science (AREA)
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• Mechanical Engineering (AREA)
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• 2016
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