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
  • B23K26/06—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
  • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
  • B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
• • 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
  • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• • 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
  • B23K26/083—Devices involving movement of the workpiece in at least one axial direction
• • 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
  • B23K26/20—Bonding
  • B23K26/21—Bonding by welding
  • B23K26/24—Seam welding
  • B23K26/244—Overlap seam welding
• • 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
  • B23K26/20—Bonding
  • B23K26/32—Bonding taking account of the properties of the material involved
  • B23K26/324—Bonding taking account of the properties of the material involved involving non-metallic parts
• • 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
  • B23K26/50—Working by transmitting the laser beam through or within the workpiece
• • 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
  • B23K26/50—Working by transmitting the laser beam through or within the workpiece
  • B23K26/57—Working by transmitting the laser beam through or within the workpiece the laser beam entering a face of the workpiece from which it is transmitted through the workpiece material to work on a different workpiece face, e.g. for effecting removal, fusion splicing, modifying or reforming
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B23/00—Re-forming shaped glass
  • C03B23/20—Uniting glass pieces by fusing without substantial reshaping
  • C03B23/203—Uniting glass sheets
• • 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
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
  • B23K2103/52—Ceramics
• • 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
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
  • B23K2103/54—Glass

Definitions

• the invention relates to a method for laser welding of two overlapping workpieces by means of a pulsed laser beam, in particular UKP laser beam, which is directed through the one workpiece on the other workpiece and moved relative to the two workpieces in a feed direction to between the two abutting workpieces one To produce weld, as well as a suitable for carrying out this laser welding process laser processing machine.
• a pulsed laser beam in particular UKP laser beam
• Ultrashort pulsed (UKP) laser radiation with pulse durations less than 500 ps is increasingly used for material processing.
• the peculiarity of material processing with UKP laser radiation lies in the short interaction time of the laser radiation with the workpiece. Due to this interaction time, extreme thermodynamic imbalances can be generated in the solid state, which then lead to unique ablation or formation mechanisms.
• metals, semiconductors, dielectrics or composites can be removed with high precision with minimum heat input or formation processes of microstructures or nanostructures can be excited (eg Gottmann, J., Hermans, M., Ortmann, J., "Digital Photonic Production of Micro Structures in Glass by In-Volume Selective Laser-Induced Etching Using a High Speed Microscanner ", Physics Procedia 39, 2012, 534-541).
• the laser welding of laser-transparent glasses or other materials transparent to the laser beam, partially transparent or scattering by means of ultrashort laser pulses enables a stable connection without additional material input, but is limited by laser-induced transient as well as permanent voltages.
• a multiple crossing of the laser beam along the joint line of the joining partners, ie along the weld seam is therefore usually used.
• the laser-induced voltage can also be reduced by means of suitable laser and / or process parameters, which, however, can result in other disadvantages (gap bridging capability).
• the background is the local melting of the material by means of ultrashort laser pulses. Focusing ultrashort laser pulses into the volume of glass, e.g.
• Quartz glass the high intensity in focus leads to non-linear absorption processes, whereby various material modifications can be induced, depending on the laser parameters. If the temporal pulse interval is shorter than the typical heat diffusion time of the glass, the temperature in the focus area increases from pulse to pulse (so-called heat accumulation). and can lead to local melting. If one places the modification in the area of the interface of two glasses, the cooling melt generates a stable connection of both glasses. Due to the local joining process, the laser-induced voltages are typically low, which can also thermally different glasses are bonded. However, these stresses affect the strength and can imitate the feasibility of laser bake I imi.
• a line-shaped weld can specify a preferred plane along which cracks can propagate, which is therefore disadvantageous for the strength and can lead to material failure (breakage).
• the present invention therefore has as its object to reduce in a method of the type mentioned in the laser-induced stresses in the workpieces to be welded together and a sufficiently stable
• This object is achieved in accordance with the invention by superposing a deflection of the laser beam in the direction of movement of the laser beam moved in the feed direction.
• the outward and outward deflection of the laser beam can take place transversely, in particular vertically, or parallel to the feed direction.
• the deflection of the laser beam transversely to the feed direction comprises any deflection of the laser beam which does not run parallel to the feed direction.
• the back and forth deflection of the laser beam perpendicular to the feed direction can also take place in the beam propagation direction.
• the laser focus is advantageously not at the level of the joining surface, but in the volume of the lower or upper workpiece just below or above its joining surface. In this way, a melt volume can arise, which does not include the joining surfaces of the two workpieces.
• the dynamic deflection of the laser beam transversely or parallel to the feed direction during the passage of the laser beam makes it possible to reduce or redistribute laser-induced stresses during the welding process, so that a higher strength is achieved in comparison to conventional welding.
• the zigzag or serpentine weld seam produced by the dynamic deflection of the laser beam transversely to the feed direction produces on average lower stress or stress birefringence than in the case of a straight-line weld seam, with stress maxima occurring separately from one another.
• Microscopic displacements (strains) due to the change in volume of the workpiece material can not accumulate along a preferred direction and thus predetermine no break line.
• the required stability of the welded joint can be generated in a single pass.
• the invention makes it possible to increase the strength of laser-bonded workpieces independently of whether the joining partners are subsequently treated for further quality improvement or not. Furthermore, the effective size of the molten surface can be increased, which in turn can improve the stability of the joint connection. Further advantages result from the fact that the melt volume increases and at the same time its geometry can be controlled more flexibly than before. The advantages of this melt, which is controlled in volume and geometry in a single pass, can be exploited both in terms of strength and throughput.
• At least one workpiece is made of glass, in particular quartz glass, of polymer, glass ceramic, crystals or combinations thereof and / or with opaque materials and has a transparency of at least 90% at the laser wavelength.
• This value refers to linear absorption processes of the laser beam in uncontaminated material.
• the relative movement of the laser beam in the feed direction and transversely or parallel to the feed direction can be achieved solely by moving the workpieces, solely by deflecting the laser beam or by a combination thereof become.
• the two workpieces are preferably moved exclusively in the feed direction and at the same time the laser beam is deflected exclusively transversely or parallel to the respective feed direction.
• the feed speed and the deflection speed are advantageously selected such that the deflection speed is between 0.01 times and 100 times the feed rate.
• the relative movement of the laser beam in the feed direction can take place along any arbitrary trajectory.
• the two workpieces are moved at a constant feed rate in the feed direction and the laser beam is deflected periodically with the same amplitude across or parallel to the feed direction, in the former case a weld in the form of a regular zigzag line or a sine curve to create.
• the welding process is based in particular on an absorption of the laser beam induced by nonlinear effects, which leads to the fact that the modification threshold of the respective material is exceeded, so that a permanent modification of the material occurs.
• the parameters of all or part of the laser pulses are selected so that non-linear absorption processes occur and, as a result, the modification threshold is exceeded.
• the welding process is initiated by one or more pulses whose parameters are selected such that processes occur which are induced by non-linear absorption and which lead to permanent material modifications.
• the invention also relates to a laser processing machine for the laser welding of two overlapping workpieces, of which at least one, in particular also the other, has a transparency of at least 90% at the laser wavelength, with a laser, in particular a UKP Laser, for generating a pulsed laser beam, in particular in the form of UKP laser pulses, with a scanner for deflecting the laser beam transversely or parallel to a feed direction and with a machine controller programmed to control the scanner such that a Movement of the Laser beam is superimposed in the feed direction a directed transversely or parallel to the feed direction back and forth deflection of the laser beam.
• a laser in particular a UKP Laser
• a scanner for deflecting the laser beam transversely or parallel to a feed direction
• a machine controller programmed to control the scanner such that a Movement of the Laser beam is superimposed in the feed direction a directed transversely or parallel to the feed direction back and forth deflection of the laser beam.
• the movement of the laser beam in the feed direction can be effected by the scanner and / or by a movement unit for moving the two overlapping workpieces in a feed direction.
• the scanner is formed by at least one electro-optical, acousto-optical, piezover foundeden or based on micro-electro-mechanical system technology deflector (scanner mirror).
• FIG. 1 schematically shows a laser processing machine for laser welding two laser-transparent workpieces by means of a laser beam, wherein the upper workpiece is shown partially broken away;
• FIGS. 2a, 2b show two different welds according to the invention on two laser-welded workpieces, wherein the upper workpiece is shown partially broken away;
• FIG. 3 shows the polarization contrast intensity of a rectilinear and a zigzag weld on two laser-welded workpieces, each in a plan view of the lap joint of the two laser-welded workpieces.
• the laser processing machine 1 shown in Fig. 1 is used for laser welding two overlapping workpieces 2a, 2b by means of a laser beam 3, wherein at least the top in Fig. 1 workpiece 2a, in particular also other, lower workpiece 2b, a transparency of at least 90% at the La laser wavelength and, for example, glass, in particular quartz glass, from
• Polymer glass-ceramic, crystalline or combinations thereof and / or is formed with opa ken materials.
• the laser processing machine 1 comprises a UKP laser 4 for generating the laser beam 3 in the form of UKP laser pulses 5 with pulse durations of less than 500 ps, in particular less than 10 ps, a movement unit (eg workpiece table) 6 movable in the XY direction to the common Moving the two workpieces 2a, 2b to be welded and a scanner 7 for two-dimensional deflection of the laser beam 3 on the two workpieces 2a, 2b to be welded.
• a UKP laser 4 for generating the laser beam 3 in the form of UKP laser pulses 5 with pulse durations of less than 500 ps, in particular less than 10 ps
• a movement unit (eg workpiece table) 6 movable in the XY direction to the common Moving the two workpieces 2a, 2b to be welded
• a scanner 7 for two-dimensional deflection of the laser beam 3 on the two workpieces 2a, 2b to be welded.
• the scanner 7 is, for example, a microscanner with a high-NA microscope objective.
• the emitted by the UKP laser 4 UKP laser pulses 5 are deflected by a galvanometer scanner 7, the beam deflection is imaged via a telescope in the region of the focal plane of Mikroskopobjek- tivs.
• the laser beam 3 can be deflected by the scanner 7 in two transverse axes, and the deflected laser beam 3 is imaged by means of a telescope (not shown) onto a microscope objective of the scanner 7 located just in front of the workpiece to be processed.
• the beam deflection can also take place by means of electro-optical, acousto-optical, piezover plausibleer or on micro-electro-mechanical system engineering (MEMS) based deflectors.
• MEMS micro-electro-mechanical system engineering
• the laser beam 3 is directed onto the lower workpiece 2 b through the upper workpiece 2 a in FIG. 1 and, by moving the moving unit 6, relative to the two workpieces 2 a, 2 b along a straight line Feed path curve 8 moves to locally melt the two workpieces 2a, 2b at their abutting joining surfaces 9a, 9b and thus to connect with each other.
• the laser beam 3 moved along the feed track curve 8 becomes a back and forth deflection directed at right angles to the respective feed direction 10 (double arrow 11). superimposed on the laser beam 3, to thereby produce on the upper side 8, for example, a zigzag or serpentine weld seam 12.
• the laser focus of the focused laser beam 3 is advantageously not located on the joining surface but in the volume of the second workpiece 2b near its joining surface 9b.
• the weld seam 12 can be formed by superposing a uniform feed motion and a periodic transverse deflection of the laser beam 3 as a regular zigzag line (FIG. 2 a) or as a sine curve (FIG. 2 b).
• the zigzag or serpentine weld seam 12 causes, on average, lower stresses than a straight-line weld seam, wherein stress maxima occur separated from one another. Microscopic displacements (strains) due to the change in volume of the workpiece material can not accumulate along a preferred direction and thus predetermine no break line.
• the laser-induced voltages during the passage of the laser beam 3 are reduced or redistributed, so that a higher strength is achieved in comparison with the conventional laser welding.
• the laser beam 3 moved along the feed path curve 8 can also be overlaid with a reciprocating deflection of the laser beam 3 directed parallel to the respective feed direction 10, thereby producing a longitudinal weld seam (not shown) on the upper side 8.
• the following laser parameters are selected:
• the modification threshold at a pulse duration of about 1 ps and a laser wavelength of about 1 pm is, for example, in the case of glass in volume at about 1 to 5 J / cm 2 , at the surface at about 0.1 -0 , 5 J / cm 2 .
• a measure of the laser-induced stresses is the polarization contrast intensity, which in FIG straight line weld (curve a) and the inventive zigzag or serpentine weld (curve b) is shown.
• the induced stress in the rectilinear weld (a) is comparably high over the entire modified range and indicates a uniform, continuous stress distribution.
• Weld seam (b) shows, on average, lower maximum stresses with intensity peaks occurring separated from one another, as a result of which the strength of the laser-bonded connection is increased.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
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• Laser Beam Processing (AREA)

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• 2018
  • 2018-04-10 DE DE102018205325.1A patent/DE102018205325A1/de active Pending
• 2019
  • 2019-04-05 EP EP19717791.8A patent/EP3774675A1/de active Pending
  • 2019-04-05 CN CN201980024589.XA patent/CN111936433A/zh active Pending
  • 2019-04-05 WO PCT/EP2019/058717 patent/WO2019197298A1/de unknown
  • 2019-04-05 KR KR1020207031758A patent/KR102617598B1/ko active IP Right Grant
• 2020
  • 2020-09-28 US US17/034,126 patent/US20210008664A1/en active Pending

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