WO2023072567A1 - Procédé d'usinage d'une pièce par faisceau laser à énergie par unité de longueur constante du faisceau laser - Google Patents

Procédé d'usinage d'une pièce par faisceau laser à énergie par unité de longueur constante du faisceau laser Download PDF

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Publication number
WO2023072567A1
WO2023072567A1 PCT/EP2022/078097 EP2022078097W WO2023072567A1 WO 2023072567 A1 WO2023072567 A1 WO 2023072567A1 EP 2022078097 W EP2022078097 W EP 2022078097W WO 2023072567 A1 WO2023072567 A1 WO 2023072567A1
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WO
WIPO (PCT)
Prior art keywords
workpiece
laser beam
modification
laser
feed rate
Prior art date
Application number
PCT/EP2022/078097
Other languages
German (de)
English (en)
Inventor
Florian Sepp
Patrick Mach
Christoph Weiss
Original Assignee
TRUMPF SE + Co. KG
Wsoptics Technologies 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 TRUMPF SE + Co. KG, Wsoptics Technologies Gmbh filed Critical TRUMPF SE + Co. KG
Publication of WO2023072567A1 publication Critical patent/WO2023072567A1/fr

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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
    • B23K26/08—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
    • B23K26/02—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
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/142—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor for the removal of by-products
    • 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
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/1462—Nozzles; Features related to nozzles
    • B23K26/1464—Supply to, or discharge from, nozzles of media, e.g. gas, powder, wire
    • 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
    • B23K26/382—Removing material by boring or cutting by boring
    • B23K26/384—Removing material by boring or cutting by boring of specially shaped holes

Definitions

  • the invention is in the technical field of manufacturing metal workpiece parts using a laser beam and relates to a method in which the workpiece is modified with a laser beam in non-cutting mode with constant energy per unit area on the workpiece.
  • the cut edges may require complex mechanical post-processing.
  • Holes in which countersunk screws are to be placed during later use of a workpiece part are usually finished by machining with a drill to form the countersinks to receive the heads of the countersunk screws.
  • the laser beam can be switched to either a workpiece-separating mode or a Workpiece non-separating and at the same time non-joining mode can be used.
  • international patent application WO 2020/173970 A1 describes a method in which the cut edges of workpiece parts that have not yet been cut free are modified by a laser beam, in particular using a bevel.
  • the international patent application WO 2020225448 A1 shows the production of countersunk holes by means of a laser beam.
  • the object of the present invention is to further develop conventional methods in which a workpiece is processed with a laser beam in the non-separating mode to produce a modification, such that the modification is as homogeneous as possible.
  • the term "workpiece” designates a plate-shaped or tubular, typically metallic, component from which at least one workpiece part (good part) is to be produced.
  • the panel-shaped workpiece is typically flat.
  • the laser beam is guided by a laser processing head and emerges from a nozzle at the end.
  • the laser beam is designed in the form of a focused, rotationally symmetrical beam cone with a central beam axis (axis of symmetry).
  • Beam diameter characterizes the transverse extent of the beam, or the physical size of the beam perpendicular to the direction of propagation.
  • the focus of the laser beam is defined by that point at which the laser beam has its smallest cross-section or the smallest beam diameter.
  • the focal length indicates the distance from the main plane of the lens (or main plane of the mirror) to the focal point of an ideal, focused parallel beam. The smaller the focal length, the more the laser beam is focused and the smaller the focus diameter, and vice versa.
  • the laser processing head also serves to guide a working gas jet, which is typically, but not necessarily, emitted from the same nozzle as the laser beam and is preferably guided coaxially with the laser beam.
  • the working gas jet emerging from the nozzle is typically, but not necessarily, designed in the form of a gas cone impinging on the workpiece.
  • the workpiece in particular a plate-shaped workpiece, rests with a workpiece underside on a workpiece support.
  • the workpiece On the upper side of the workpiece, the workpiece has a (top) workpiece surface.
  • the workpiece surface is flat.
  • the “workpiece surface” here and in the following is understood to mean the upper-side workpiece surface which is opposite or facing the nozzle.
  • the opposite workpiece surface, on which the workpiece usually rests on a base, is the workpiece underside.
  • the laser processing head for guiding the laser and working gas beam can be moved relative to the workpiece in a typically horizontal plane parallel to the plane of the workpiece surface and in a typically vertical direction perpendicular thereto.
  • the reference system is always stationary with respect to the workpiece, so that the laser processing head is considered to be moving and the workpiece is considered to be stationary. Viewed locally, however, it is irrelevant whether the laser processing head or the workpiece or both are moved. In this respect, it would be equally possible for the workpiece to be moved as an alternative to the moving laser processing head, or for both the laser processing head and the workpiece to be moved.
  • the energy of the laser beam depends on the specific design of a laser source and is typically specified in joules (J).
  • the power of the laser beam ie energy per time), typically measured in joules per second (J/s) or in watts (W), describes the optical output power of a continuous wave laser (CW) or the average power of a pulsed laser.
  • Pulsed lasers are also characterized by their pulse energy, which is directly proportional to the average power and inversely proportional to the laser's repetition rate.
  • "Energy density” refers to the energy of the laser beam related to the irradiated area of the workpiece. The energy density is measured in J/mm 2 , for example.
  • the traversing speed of the laser processing head or laser beam is important for the laser processing of the workpiece, i.e. the time for how long a certain area of the workpiece is irradiated by the laser beam. It is customary to use the term "path energy" for this. This is the power of the laser beam absorbed by the workpiece per speed of the laser processing head or laser beam, e.g. measured in watts/(mm/s). If the power of the laser beam is given in watts (W) as joules per second (J/s), the energy per unit area is measured in J/mm.
  • the distance energy of the laser beam is essential, with the energy absorbed by the workpiece depending on the energy density.
  • the energy absorbed by the workpiece at a given power of the laser beam depends on the size of the beam spot on the workpiece, corresponding to the beam diameter at the point where the laser beam hits the workpiece.
  • the beam diameter of the laser beam on the workpiece results from the focus position, ie the position of the focus of the laser beam relative to the workpiece (shortest vertical distance), in particular relative to the workpiece surface on which the laser beam is directed, or also relative to the workpiece support.
  • the workpiece is in the divergent area of the beam cone (focus above the workpiece surface where the processing beam hits)
  • increasing the distance between the focus and the workpiece can increase the beam diameter on the workpiece, and vice versa.
  • the energy density of the laser beam and thus the energy absorbed by the workpiece, which is included in the path energy can be changed in a targeted manner.
  • the out-of-focus beam intensity is not constant relative to the cross-section.
  • the power intensity is a Gaussian profile. In any case, the energy density is relatively low towards the edge, especially out of focus.
  • the energy per line also depends on the speed of the laser beam, i.e. the traversing speed of the laser processing head, also known as "feed speed".
  • feed speed the speed of the laser beam
  • the line energy of the laser beam decreases, and vice versa.
  • the laser beam can be used either for separating processing or for non-separating and at the same time non-joining processing of the workpiece, i.e. in a separating (cutting) mode or non-separating mode.
  • cutting mode the distance energy of the laser beam on the workpiece is so great that the laser beam cuts (cuts) the workpiece so that the workpiece is penetrated, e.g. to create a kerf.
  • non-cutting mode the path energy of the laser beam on the workpiece is so low that the laser beam processes the workpiece in a non-cutting and non-joining manner at the same time, so that the workpiece is not penetrated, which means that a modification of the workpiece can be produced.
  • the distance energy or distance energy of the laser beam on the workpiece can be achieved in particular by changing the power of the laser beam, changing the feed speed of the laser processing head, focusing/defocusing the laser beam by changing the focus position relative to the workpiece or changing the beam diameter on the workpiece surface .
  • the type and/or composition of the process gas used in laser processing can also be changed. the.
  • the path energy of the laser beam on the workpiece is changed by changing the focus position relative to the workpiece, which is preferably effected by changing the height of the laser processing head above the workpiece or the workpiece surface facing the laser processing head, i.e. the laser processing head becomes more typical with a movement component perpendicular to the workpiece surface way in vertical direction.
  • the laser beam can or will be produced by changing its energy per unit area on the workpiece in a mode that cuts the workpiece a kerf or non-cutting mode is used to create a modification of the workpiece.
  • a modification of the workpiece selected from a chamfer, a fillet, and a trough is generated on a workpiece top surface along a modification line.
  • the modification of the workpiece is generated from a starting point of the modification line at which the laser beam is turned on to an end point of the modification line at which the laser beam is turned off. It is essential here that the modification of the workpiece is generated from the start to the end point with a constant energy per unit area of the laser beam on the workpiece. In this way, it can be achieved in an advantageous manner that a homogeneous modification with an improved quality is produced.
  • a feed rate of the laser processing head is kept constant from the starting point to the end point for generating the modification.
  • the feed rate of the laser processing head is advantageously increased to a predeterminable or specified (selectable) target value until the starting point is reached, maintained between the starting point and end point, and reduced again only after the end point has been reached.
  • the laser beam is only guided over the starting point when the laser processing head has the target speed and only after range of the end point is reduced again.
  • the start and stop of the laser processing head therefore does not take place between the start and end point. Rather, the laser processing head is approached before the starting point and brought to the target speed and only then braked again when the laser beam has passed the end point.
  • This measure makes it possible to achieve a constant energy per unit area of the laser beam on the workpiece between the starting point and the end point in a simple and reliable manner. There are no latency times for starting and stopping the laser processing head between the start and end point to create the modification.
  • a feed rate of the laser processing head is not constant between the starting point and the end point, the feed rate being increased from the starting point and reduced before the end point.
  • the energy or power of the laser beam is increased in accordance with the increase in the feed rate and reduced in accordance with the drop in the feed rate in such a way that the energy per unit area of the laser beam on the workpiece between the start and end points is kept constant.
  • a feed rate of the laser processing head is not constant between the starting and end points, the feed rate being increased from the starting point and reduced before the end point.
  • a beam diameter of the laser beam on the workpiece is reduced in accordance with the increase in the feed speed and increased in accordance with the decrease in the feed speed so that the energy per unit area of the laser beam on the workpiece between the start point and end point is kept constant.
  • the beam diameter of the laser beam on the workpiece is advantageously changed by changing the working distance between the nozzle and the workpiece.
  • the working gas jet is only switched off after the laser beam has passed the end point. In this way it can be achieved that when the modification is produced, any melt produced is reliably expelled through a cutting gap by means of the working gas jet.
  • the laser beam is used to generate a mode fication in non-separating mode along the modification line.
  • the laser processing head is moved along the modification line in a corresponding manner.
  • the laser beam does not necessarily have to be guided along the modification line in such a way that the path of the laser beam is identical to the modification line. Rather, the (overall) movement of the laser beam or of the laser processing head can result from a primary movement and a secondary movement superimposed on the primary movement.
  • the path of the laser beam is identical to the modification line, so that the laser beam is always aimed at the modification line.
  • Secondary motion also includes motion components transverse (ie, perpendicular) to the modification line, such that a larger area of the workpiece is swept by the laser beam.
  • the trajectory of the laser beam along the modification line is identical to the modification line.
  • a modification of the workpiece is thus produced by guiding the laser beam along the modification line, which enables the workpiece to be modified particularly quickly.
  • the (overall) movement of the laser beam is then identical to the primary movement.
  • the laser beam transversely to the modification line in order to produce the modification.
  • a secondary movement is superimposed on the primary movement of the laser beam, with the laser beam performing a meandering back and forth movement along the modification line according to a preferred embodiment of the method according to the invention.
  • the laser beam is repeatedly guided away from the modification line and guided back towards it in each case.
  • the laser beam is guided along respective closed path sections, which are preferably arranged in rows along the modification line. Each closed path section is defined by crossing the previously traversed path of the laser beam.
  • the closed path sections are circularly closed path sections (ie circles) or ellipses, which are preferably arranged in a row along the modification line.
  • chamfers with greater depths and/or widths can be produced along the modification line.
  • a movement component of the laser beam transverse to the modification line has an extension of at least 0.5 mm and at most 5 mm.
  • the laser beam preferably has sections, in particular long of circles or ellipses, have an overlap along the modification line in the range from 0.5 mm to 1 mm.
  • An overlap of the closed path sections (eg circles) along the modification line is advantageously 0.5 mm to 1 mm.
  • countersunk holes are produced in the workpiece.
  • the laser beam is guided once or several times in the non-cutting mode along at least one closed modification line, with a depression being produced as a modification of the workpiece.
  • the laser beam is guided along a closed cutting line to create a hole in the workpiece, the hole being within the countersink when viewed perpendicularly through the workpiece.
  • countersunk holes are produced in two stages, with a preliminary hole being produced first, which is then widened to form a final hole.
  • the laser beam is guided in the cutting mode along a closed pre-hole cutting line, which creates a pre-hole in the workpiece.
  • the laser beam is then guided in non-cutting mode once or several times along at least one closed countersink generation line, with the countersink generation line being arranged in relation to the pre-hole intersection line in such a way that a countersink surrounding the pre-hole and ending in the pre-hole is generated as a modification of the workpiece.
  • the laser beam is then guided in the cutting mode along a closed end-hole cutting line, with the end-hole cutting line being arranged in relation to the pre-hole cutting line in such a way that the pre-hole is widened to produce an end hole, with the end hole extending perpendicularly through the workpiece within the lowering is located.
  • At least one workpiece part and a residual workpiece are produced from the workpiece, the workpiece being modified with the laser beam in non-cutting mode.
  • step a) and step b) can be carried out in any order in the method.
  • step a) can be carried out before step b) and according to a second variant of the method, step b) can be carried out before step a).
  • step b) no closed cutting gap is produced. Rather, the workpiece part remains connected to the rest of the workpiece.
  • step b) at least one part of at least one of the cutting edges on the workpiece part or on the remaining workpiece is provided with a chamfer or a rounding.
  • a trough is first produced in step b) as a modification of the workpiece on the upper side of the workpiece.
  • step a) the workpiece is severed by creating a closed kerf along the cutting line or alternatively by creating a section of the kerf along the cutting line. It is essential here that the cutting line is arranged within the trough, i.e. the closed kerf or the section of the kerf is generated within the trough.
  • the beam axis of the laser beam is typically always directed perpendicular to the flat workpiece support or perpendicular to the plane of the irradiated upper workpiece surface, ie the angle between the beam axis and the workpiece support is 90°.
  • This entails technical control advantages.
  • costs for the technical implementation of a corresponding pivotability of the laser beam relative to the plane of the workpiece support can be saved.
  • the beam axis it is also conceivable for the beam axis to be changed when the workpiece is irradiated, with the beam axis at least temporarily assuming an angle other than 90° to the workpiece support or to the plane of the irradiated upper workpiece surface.
  • the laser beam can be aligned by pivoting the laser processing head (mechanically) and/or by pivoting the laser beam (optically). For example, by pivoting the Laser beam can be swept over a larger area of the workpiece during the generation of a modification, which can be advantageous.
  • the invention also extends to a laser processing device with a laser beam guided by a laser processing head for laser processing a plate-shaped or tubular workpiece, which has an electronic control device for controlling/regulating the laser processing of the workpiece, which is set up (in terms of programming) to carry out the method according to the invention described above is.
  • the invention extends to a program code for an electronic control device suitable for data processing for such a laser processing device, which contains control commands that cause the control device to carry out the method according to the invention.
  • the invention also extends to a computer program product (storage medium) with a stored program code for an electronic control device suitable for data processing for such a laser machining device, which contains control commands that cause the control device to carry out the method according to the invention.
  • FIG. 1 shows a schematic representation of an exemplary laser beam processing device for carrying out the method according to the invention for laser beam processing of a plate-shaped or tubular workpiece
  • 2A-2C show an embodiment of the method according to the invention for laser beam machining of a workpiece, in which countersunk holes are produced become;
  • Fig. 4 is a rolled-up sectional view of the countersunk hole workpiece of Fig. 3 in the area of the chamfered hole made in the conventional manner;
  • Figure 5 is a rolled-up sectional view of the countersunk hole workpiece of Figure 3 in the area of the chamfered hole made in accordance with the present invention
  • FIG. 6 shows a schematic representation to illustrate the distance energy P(s) of the laser beam on the workpiece and the traversing speed v(s) of the laser processing head, as well as the developed countersink in a sectional view, produced according to an exemplary embodiment of the method of the invention
  • FIG. 7 is a schematic diagram showing the line energy P(s) of the laser beam on the workpiece and the traversing speed v(s) of the laser processing head, as well as the developed countersink, produced according to a conventional method.
  • the laser beam processing device comprises a beam cutting device 2 with a laser processing head 3, and a work table 4 with a flat workpiece support 5 for a workpiece 9 (not shown in Figure 1, see Figures 2A-2C), for example a flat metal sheet.
  • the workpiece support 5 is spanned by a crossbeam 6, which is guided to be movable along a first axial direction (x-direction).
  • a guide carriage 7 for the jet head 3 is mounted on the crossbeam 6, which carriage is mounted on the crossbeam 6 along a second axis direction perpendicular to the first axis direction (y-direction) is movably guided.
  • the laser processing head 3 can thus be moved in a plane spanned by the two axial directions parallel and relative to the workpiece support 5, which is horizontal for example.
  • the height of the laser processing head 3 is also designed to be movable in a third axis direction (z-direction) perpendicular to this plane, as a result of which the distance perpendicular to the workpiece support 5 or workpiece 9 can be changed.
  • the z-direction corresponds to the direction of gravity.
  • the laser processing head 3 On its side facing the workpiece support 5 , the laser processing head 3 has a (jet) nozzle 13 that tapers conically towards the workpiece support 5 .
  • the laser processing head 3 is used to guide a laser beam 14 and a process or working gas jet 15, which emerge from a terminal nozzle tip 19 (see, for example, FIG. 2A).
  • the laser beam 14 is generated by a laser beam source 8 and guided to the laser processing head 3, for example, through a beam guiding tube and several deflection mirrors or an optical fiber cable.
  • the laser beam can be directed onto the workpiece 9 in a bundled form (ie focused) via a focusing lens or adaptive optics. Due to the movability of the laser processing head 3 along the first axial direction (x-direction) and second axial direction (y-direction), any desired point on the workpiece 9 can be approached with the laser beam 14 .
  • the workpiece 9 has two opposite workpiece surfaces 10, 11 (see e.g. Figure 2A), with a first or upper workpiece surface 10 facing the nozzle 13 and a second or lower workpiece surface 11 facing away from the nozzle 13. Due to the height movability of the laser processing head 3 in the z-direction, the working distance of the nozzle 13 to the workpiece 9 can be adjusted by changing the distance to the upper workpiece surface 10 . The distance of the laser processing head 3 from the upper workpiece surface 10 can be adjusted before, during and after the laser beam processing. The focal position of the laser beam 14 can be adjusted by changing the distance between the nozzle 13 and the first workpiece surface 10 and by means of optical elements in the beam head 3, for example adaptive optics.
  • the working gas jet 15 is generated by a gas jet generating device, not shown. Helium (He), argon (Ar) or nitrogen (N 2 ), for example, is used as the inert process or working gas. Oxygen (O 2 ) is usually used as the reactive working gas. The use of gas mixtures is also known.
  • the working gas jet 15 emerges from the nozzle tip 19 of the nozzle 13 and is coaxial to The laser beam 14 is guided to the processing point and strikes the workpiece 9 there with an (initial) gas pressure specified by the gas jet generating device, which is typically in the range from 2 to 20 bar.
  • the working gas jet 15 serves to drive the melt produced during the laser processing through an opening (hole 16, see eg FIG. 2A) in the workpiece 9 produced by the laser beam 14 by means of gas pressure.
  • the flat workpiece support 5 consists, for example, of a large number of support elements with, for example, triangular support point tips, which together define a support plane for the workpiece 9 to be machined.
  • the support elements are designed here, for example, as elongate support webs, each of which extends along the y-direction and are arranged next to one another in a parallel arrangement along the x-direction, for example with a constant spacing between them.
  • a suction device through which cutting smoke, slag particles and small pieces of waste produced during jet cutting can be sucked off.
  • a program-controlled control device 12 serves to control/regulate the method according to the invention for laser beam machining of the workpiece 9 in the laser beam machining device 1 .
  • FIGS. 2A to 2C in which an exemplary embodiment of the method according to the invention for laser beam machining of a workpiece 9 by the laser machining device 1 of FIG. 1 is illustrated.
  • FIGS. 2A to 2C For the purpose of a simplified illustration and because it is sufficient for understanding the invention, only the nozzle 13 and the laser beam 14 and working gas jet 15 are shown in combination with the workpiece 9.
  • the workpiece 9 is, as usual, in a horizontal position on the workpiece support 5.
  • the right-hand images in FIGS. 2A and 2B illustrate the process steps in a schematic manner using respective top views.
  • the workpiece 9 is modified, with a countersink 17 or chamfer being produced around a hole 16 .
  • the upper workpiece surface 10 faces the nozzle 13 and the lower workpiece surface 11 faces away from the nozzle 13 .
  • the laser beam 14 emerging from the nozzle tip 19 of the nozzle 13 and the working gas jet 15 strike the workpiece 9.
  • the laser beam 14 has the form of a focused one Beam cone with a central beam axis 18. The central beam axis 18 and thus the laser beam 14 are directed perpendicularly to the upper workpiece surface 10 or to the plate-shaped workpiece 9 level.
  • FIG. 2A A process situation is shown in FIG. 2A in which a hole 16 in the workpiece 9 was cut out by the laser beam 14 .
  • the nozzle 13 was moved from a starting position towards the workpiece 9 with at least one vertical movement component, so that the nozzle 13 had a relatively small working distance from the workpiece 9 .
  • the working distance of the nozzle 13 from the upper workpiece surface is preferably less than 2 mm.
  • the focal position of the laser beam 14 results in a narrow beam spot with a small beam diameter on the workpiece 9.
  • the focal position and thus the beam diameter were selected in such a way that the energy per unit length of the laser beam 14 on the workpiece 9 was so great that the laser beam 14 could be used for cutting or separating machining of the workpiece 9 was suitable.
  • the laser beam 14 was in a cutting mode.
  • the laser beam 14 was guided along a circular cutting line (21) creating a circular-closed kerf.
  • a workpiece part (slug) with a round or disc-shaped cross section was completely cut out of the workpiece 9 .
  • the cut slug fell away under its own weight.
  • the hole 16 with a round cross-section and a selectable diameter was produced in the workpiece 9, as shown in FIG. 2A.
  • the hole 16 is a through hole according to the way it is produced and breaks through the workpiece 9.
  • the round hole 16 is radially symmetrical in relation to its central axis 20.
  • FIG. A radial direction is defined in the plane of the workpiece 9 with respect to the hole 16 and its central axis 20 .
  • the method can be supplemented with a step that is carried out before the hole 16 is cut.
  • This step is preferably used when holes 16 with a diameter of at least 7 mm are to be produced and/or the workpiece 9 is at least 4 mm thick.
  • the slug to be cut later on its contour is cut into smaller parts by one or more cutting gaps, which can always ensure that the slug falls reliably and safely down out of the workpiece 9 and the cut-out hole 16 is always free.
  • cutting gaps crossing one another possibly superimposed by a cutting gap in spiral form, introduced.
  • a possible method for dividing the slug is described, for example, in US Pat. No. 8,716,625 B2.
  • the nozzle 13 has a relatively large working distance from the first workpiece surface 10 or from the workpiece 9, with the workpiece 9 being in the divergent area of the laser beam 14, resulting in a wide beam spot with a large beam diameter on the workpiece 9 leads.
  • the laser processing head 3 or the nozzle 13 was moved away from the workpiece 9 with at least one vertical movement component, so that in comparison to the production of the hole 16 there is a larger working distance between the nozzle
  • the working distance for producing countersink 17 is, for example, at least 6 times larger, in particular at least 10 times larger, than the working distance for producing hole 16 and is preferably at least 30 mm, particularly preferably at least 40 mm and in particular approx. 50 mm, with a range of 30 mm to 50 mm is preferred.
  • the beam spot and the beam diameter on the workpiece 9 are significantly larger.
  • the cross-sectional area of the beam spot on the workpiece 9 is at least 6 times larger, in particular at least 10 times larger.
  • the focus of the laser beam 14 is far above the workpiece 9.
  • the focus position and the beam diameter of the laser beam 14 are selected in such a way that the energy per unit area on the workpiece 9 of the laser beam 14 is relatively low and the laser beam 14 produces the countersink 17, with the workpiece 9 is not penetrated here (non-separating processing).
  • the laser processing head 3 or the nozzle 13 When producing the countersinking 17, the laser processing head 3 or the nozzle 13 has a constant feed rate, which corresponds to a predetermined (selectable) target value for the feed rate.
  • the laser processing head 3 or the nozzle 13 In order to ensure that the laser processing head 3 or the nozzle 13 already has the desired value when the countersink 17 begins to be produced, the laser processing head 3 or the nozzle 13 is moved in a circular motion around the central axis 20 with the working gas jet 15 switched on but the laser beam 14 switched off , until the laser processing head 3 or the nozzle 13 has the desired value.
  • the laser processing head 3 or the nozzle 13 is here already proceed directly above the modification line 22 to create the modification (lowering 17). This is illustrated in FIG. 2A using the arrow around the central axis 20.
  • the laser beam 14 is ignited and the depression 17 is produced. Due to the reduced path energy of the laser beam 14 on the workpiece 9, the laser beam is not in the non-separating mode and the workpiece 9 is not penetrated when the depression 17 is produced.
  • the non-cutting laser beam 14 is moved in a (horizontal) plane parallel to the plane of the workpiece support 5 , the laser beam 14 being moved along the modification line 22 .
  • the modification line 22 is concentric with the line of intersection 21 of the hole 16, but offset further radially outwards. This means that the modification line 22 has a diameter that is larger than the diameter of the hole 16.
  • a single modification line 22 can be provided for producing the countersink 17 , the laser beam 14 being moved along the modification line 22 one or more times to produce the countersink 17 .
  • the laser beam 14 is preferably moved several times along the modification line 22 to produce the countersinking 17 (typically 2 to 20 passes over the nozzle 13).
  • the modification line 22 is arranged in such a way that the countersink 17 produced is directly adjacent to the hole 16, i.e. opens into the hole 16.
  • a plurality of modification lines 22 can also be provided for producing the countersink 17 , with the laser beam 14 being moved one or more times along each modification line 22 to produce the countersink 17 .
  • the plurality of modification lines 22 are preferably arranged concentrically with one another.
  • the countersink 17 is a depression in the workpiece 9 on the first workpiece surface 10 and concentrically surrounds the hole 16, with the countersink 17 starting from a (radial) outer countersink edge 23, extending from the upper workpiece surface 10 into the workpiece 9 up to extends to a (radially) inner countersink edge 24, but not to the lower workpiece surface 11, ie the countersink 17 does not extend over the entire thickness of the workpiece part.
  • the inner countersink edge 24 is thus located between the upper workpiece surface 10 and the lower workpiece surface 11.
  • the outer countersink edge 23 is defined as that area of the workpiece 9 where the countersink 17 begins to deepen towards the interior of the workpiece 9.
  • the inner countersink edge 24 is defined as that area of the workpiece 9 at which the countersink 17 merges into the remaining part of the hole 16.
  • a flank 25 of the countersink 17 extends from the outer countersink edge 23 to the inner countersink edge 24.
  • FIG. 2B shows an example of a countersink 18 with a sloping flank 25 with an inclination of approximately 45°, with larger or smaller flank inclinations also being possible.
  • FIG. 2B the circular movement of the laser processing head 3 or laser beam 14 along the modification line 22 around the central axis 20 of the hole 16 for producing the countersink 17 is illustrated schematically by an arrow.
  • the traversing speed of the laser processing head 3 is constant at the desired value while the depression 17 is being produced. This also applies when the production of the depression 17 is terminated, i.e. the laser beam 14 is switched off.
  • FIG. 2C shows a process situation in which the depression 17 has already been completely produced.
  • the laser processing head 3 or the nozzle 13 is moved at the setpoint speed about the central axis 20 until the laser beam 14 is switched off, and is braked only after the laser beam 14 has been switched off. In this way, the countersink 17 can be produced with a uniform depth and slope of the flank 25 .
  • the working gas jet 15 is still switched on. Through the hole 16, the melt (slag) produced when the depression 17 is created can be easily discharged downwards by means of the working gas jet 15 and the melt can be prevented from reaching the upper workpiece surface 10 of the workpiece 9 and solidifying there and forming a burr forms.
  • the countersink 17 can be used in any desired manner, and in this exemplary embodiment it is preferably intended to accommodate the head of a countersunk screw.
  • Oxygen (O 2 ) is used as the process or working gas in the production of the depression 17, with a gas pressure of, for example, less than 5 bar, which is in particular from 2 to 3.5 bar.
  • the constant feed rate of the nozzle 13 when creating the reduction 17 is preferably at least 4 m/min and the laser power of the laser beam 14 is preferably at least 1500 W.
  • FIG. 3 shows a section through the workpiece 9 (perpendicular to the plane of the workpiece 9).
  • the sunken hole 16 is clearly visible.
  • the hole 16 is delimited by the hole wall 26 .
  • the depression 17 is bounded by the wall 27 of the depression.
  • FIG. 4 the unrolled, countersunk hole 16 is shown in a section corresponding to FIG.
  • the viewer's gaze is directed to the hole wall 26 and the countersink wall 27 .
  • a chamfered hole 16 produced in a conventional manner is illustrated in FIG. Due to the inertia of the laser processing head 3 when starting up, the energy per line of the laser beam 16 on the workpiece 9 is typically increased at the beginning of the creation of the countersink 17 at the starting point 28 of the modification line, so that the countersink 17 has a greater depth T than later, when the Laser processing head 3 has already reached the target speed.
  • the laser processing head 3 is typically decelerated before reaching the end point 29 of the modification line, so that the energy per unit length of the laser beam 16 on the workpiece 9 increases again and the bevel is deepened. Due to the round reduction 17 start point 28 and end point 29 coincide.
  • FIG. 5 shows a chamfered hole 16 produced in accordance with the invention, as explained in FIGS. 2A to 2C.
  • the laser processing head 3 was already at its target speed for creating the countersink 17 and maintained this speed until the end point 29 was reached. In this way, a countersink 17 with a homogeneous depth T could be produced.
  • FIG. 6 relates to the method according to the invention, and FIG. 7 to the conventional method.
  • the laser processing head 3 or nozzle 13 is approached before the starting point 28 is reached in order to produce the countersink 17, with the feed rate v(s) of the laser processing head 3 being increased, for example linearly, up to the desired setpoint value.
  • the setpoint is reached.
  • the feed rate v(s) of the laser processing head 3 is kept constant between the starting point 28 and the end point 29 . After reaching the end point 29, the feed speed v(s) of the laser processing head 3 is reduced, for example linearly. This results in a constant line energy P(s) of the laser beam 16 on the workpiece 9 and the depression 17 is produced with a homogeneous depth.
  • Figure 7 shows the conventional case in which the laser processing head 3 is first approached at the starting point 28, recognizable from an increase in the feed rate v(s) after the starting point 28 and is reduced again before the end point 29 is reached, recognizable from the drop in the Feed speed v(s) of the laser processing head 3 in front of the end point 29.
  • the feed rate of the laser processing head is not constant between the start and end points, with the feed rate increasing from the starting point and decreasing before the end point, with a power of the laser beam corresponding to the increase of the feed rate is increased and corresponding to the drop in the feed rate reduced in such a way that the distance energy of the laser beam on the workpiece between the start and end point is kept constant.
  • a feed rate of the laser processing head is not constant between the start point and the end point, the feed rate being increased from the start point and decreased before the end point, a beam diameter of the laser beam on the workpiece being reduced in accordance with the increase in the feed speed and thus in Correspondence to the drop in feed rate is increased so that the distance energy of the laser beam on the workpiece between the start and end point is kept constant.
  • the chamfer/countersink is created.
  • An optimum feed rate for creating the countersink is 6 m/min.
  • the diameter of the modification line to create the countersink is 7.9 mm.
  • a circuit with a diameter of 7.9 mm is run without the laser beam switched on.
  • the laser beam is switched on "on the fly” and the countersink/chamfer is then created.
  • the laser beam is switched off "on the fly” and the laser processing head completes another revolution with the laser beam switched off until the machine axes have reached a feed rate of 0 m/min.
  • the invention provides a novel method for laser beam machining of a workpiece, in which a modification of the workpiece, in particular a chamfer or countersink, can be produced in a homogeneous manner. Increased path energies of the laser beam on the workpiece at the start and end point due to the latency when starting and braking the laser processing head are avoided in an advantageous manner.
  • the modifications of the workpiece can be efficiently produced in a simple and cost-effective manner with high precision and quality.
  • An implementation of the method according to the invention in already existing laser beam processing devices is possible in a simple manner without having to provide complex technical measures for this purpose. Rather, a desired laser beam processing of a workpiece can be realized by the method according to the invention simply by intervening in the machine control.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

L'invention concerne un procédé d'usinage par faisceau laser d'une pièce au moins partiellement plane (9) au moyen d'un faisceau laser (16) et d'un jet de gaz de travail (15) pour évacuer les matériaux fondus de pièce, lesdits faisceau laser et jet de gaz de travail sortant conjointement d'une buse (13) d'une tête d'usinage laser (2) ; la modification de l'énergie par unité de longueur du faisceau laser permettant d'utiliser ledit faisceau laser (14) sur la pièce (9) dans un mode de découpe de pièce (9) pour produire une fente de coupe ou dans un mode de non-découpe pour une produire une modification de la pièce ; une modification de la pièce (9), sélectionnée parmi un chanfrein (21), un arrondi et une cavité, étant produite sur une face supérieure de la pièce le long d'une ligne de modification (22) au moyen du faisceau laser (16) dans le mode de non-découpe ; le faisceau laser (16) étant activé au niveau d'un point de départ (28) de la ligne de modification (22) et étant désactivé au niveau d'un point terminal (29) de la ligne de modification (22) ; la modification de la pièce étant produite du point de départ jusqu'au point terminal avec une énergie par unité de longueur constante du faisceau laser (16) sur la pièce (9).
PCT/EP2022/078097 2021-10-25 2022-10-10 Procédé d'usinage d'une pièce par faisceau laser à énergie par unité de longueur constante du faisceau laser WO2023072567A1 (fr)

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DE102021005298.6 2021-10-25

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US8716625B2 (en) 2012-02-03 2014-05-06 Trumpf Werkzeugmaschinen Gmbh + Co. Kg Workpiece cutting
DE202009018923U1 (de) * 2009-09-08 2014-06-26 Ewm Hightec Welding Gmbh Vorrichtung zum Ermitteln einer Schweiß- oder Lötgeschwindigkeit
DE102013109588A1 (de) * 2013-09-03 2015-03-05 Gsi Helmholtzzentrum Für Schwerionenforschung Gmbh Aufschmelz-Verbindungsverfahren
WO2020173970A1 (fr) 2019-02-25 2020-09-03 Wsoptics Technologies Gmbh Processus d'usinage par faisceau d'une pièce en forme de panneau ou de tube
WO2020225448A1 (fr) 2019-05-08 2020-11-12 Wsoptics Technologies Gmbh Procédé d'usinage par faisceau d'une pièce

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WO2016033494A1 (fr) 2014-08-28 2016-03-03 Ipg Photonics Corporation Systeme et procede de biseautage et/ou de polissage par laser
JP7387870B2 (ja) 2019-07-29 2023-11-28 ダブリュ・エス・オプティクス テクノロジーズ ゲー・エム・ベー・ハー 板状または管状のワークピースをビーム加工するための方法
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DE202009018923U1 (de) * 2009-09-08 2014-06-26 Ewm Hightec Welding Gmbh Vorrichtung zum Ermitteln einer Schweiß- oder Lötgeschwindigkeit
US8716625B2 (en) 2012-02-03 2014-05-06 Trumpf Werkzeugmaschinen Gmbh + Co. Kg Workpiece cutting
DE202012102318U1 (de) * 2012-06-22 2012-07-12 Stiwa Holding Gmbh Fügeverbindung zwischen metallischen Bauteilen und Schweißvorrichtung
DE102013109588A1 (de) * 2013-09-03 2015-03-05 Gsi Helmholtzzentrum Für Schwerionenforschung Gmbh Aufschmelz-Verbindungsverfahren
WO2020173970A1 (fr) 2019-02-25 2020-09-03 Wsoptics Technologies Gmbh Processus d'usinage par faisceau d'une pièce en forme de panneau ou de tube
WO2020225448A1 (fr) 2019-05-08 2020-11-12 Wsoptics Technologies Gmbh Procédé d'usinage par faisceau d'une pièce

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