A method for pre-treating slender conductors for use in a welding process, and a machine tool for performing the method.

Abstract

The present invention relates to a method for pretreating an elongated conductor (10) for a welding process, wherein the elongated conductor (10) has a conductive core (12) and a cladding (14), and the core (12) comprises aluminum, the method comprising the steps of: removing the cladding (14) within a segment (20) of the elongated conductor (10); and heating the conductive core (12) by irradiating the segment (20) with a laser beam (18) to form an oxide layer (38) within the segment (20).

Description

Technical Field

[0001] The present invention relates to apparatus and method for pre-treating elongated conductors for use in welding processes, as well as machine tools. Background Technology

[0002] DE 10 2020 212 087 A1 describes a method for removing a non-conductive plastic coating from a conductive metal core of a conductor. The plastic coating is removed by repeatedly irradiating it with laser radiation.

[0003] The purpose of this invention The object of this invention is to provide a method for pre-treating elongated conductors for use in a welding process, a method with improved performance, particularly in its superior pre-treating of elongated conductors for welding. Furthermore, the object of this invention is to provide a machine tool configured to perform such a method. Summary of the Invention

[0004] This objective is achieved by providing a method having the features of claim 1 and a machine tool having the features of claim 11. Advantageous extensions and / or embodiments of the invention are described in the dependent claims.

[0005] A method according to the invention is designed for pretreating elongated conductor members for a welding process. The elongated conductor member has a conductive core and a cladding. The core comprises aluminum. The method includes the steps of: removing the cladding within a segment of the elongated conductor member; and heating the conductive core in the segment by irradiating it with a laser beam to form an oxide layer therein.

[0006] The formation of the oxide layer advantageously allows for better retention of the molten material in its position during subsequent welding processes, where the section will at least partially melt. In other words, the formed oxide layer prevents undesirable runoff and / or flow away from the welding area of ​​the molten material generated during the welding process. In other words, the formed oxide layer helps the molten material generated during the welding process, thereby particularly preventing undesirable runoff. For this purpose, the oxide layer can float on the molten material during the welding process. Therefore, the oxide layer allows for the formation of stable molten droplets during subsequent welding processes, thereby preventing undesirable contact between, for example, the cladding and the molten material. In particular, due to the aiding effect of the oxide layer on the molten material during the welding process, a higher quality weld joint produced by the welding process can be achieved. Therefore, the method according to the invention advantageously enables better pretreatment of elongated conductors for the welding process.

[0007] In particular, pretreatment can be understood as the pre-preparation of slender conductors for use in the welding process.

[0008] A slender conductor can be called a conductive element; in particular, a slender conductor can be constructed as a conductive element.

[0009] Elongated conductors can be adapted to be arranged in an electric motor, for example, to form the stator of the motor. When arranged in the stator and electrically connected to each other, multiple elongated conductors can be used to generate the magnetic field required for the operation of the motor. The electrical connection of multiple elongated conductors to each other can be achieved by means of a welding process.

[0010] The elongated conductor can be constructed as a hairpin, and in particular, the elongated conductor can be a hairpin. The hairpin can have two elongated legs, particularly two elongated legs oriented parallel to each other, connected to each other by means of a connecting section. The hairpin can be hairpin-shaped. In other words, the hairpin can be U-shaped. Alternatively, the elongated conductor can be designed as a sonderpin. The sonderpin can have one leg, or in particular, a single leg. The elongated conductor can also be a combination of a hairpin and a sonderpin.

[0011] The elongated conductor can have a rectangular cross-section. In particular, the core can have a rectangular cross-section. The elongated conductor can be constructed as a rod-shaped conductor with a rectangular conductor cross-section. The side length of the elongated conductor can be between 0.2 mm and 15 mm, preferably between 2 mm and 8 mm.

[0012] The cladding can surround the core in the radial direction, particularly outward. The cladding can be an electrical insulator. In particular, the cladding can electrically insulate the core from its environment. The cladding can have a dielectric strength of 20 kV / mm to 60 kV / mm. The cladding can be a varnish. Preferably, the cladding can be made of polyamide-imide (PAI), polyetheretherketone (PEEK), or a combination of polyamide-imide and polyimide film (PAI+FEP). The cladding can be a single layer or multiple layers. Exemplarily, the cladding can have one layer made of polyamide-imide and another layer made of polyetheretherketone. The cladding can be transparent to visible light.

[0013] An aluminum-containing core can be understood to mean that the core is made of an aluminum alloy, or particularly composed of an aluminum alloy. Preferably, the aluminum-containing core can be made of an aluminum-based alloy, wherein the weight percentage of aluminum is at least 75%, 80%, 90%, 95%, or 98%. The core can be made of aluminum, particularly composed of aluminum. For example, the aluminum-containing core can be made of material EN AW-1050A.

[0014] The oxide layer can be adapted to stabilize the molten material generated during the welding process. In particular, the oxide layer can be adapted to prevent accidental separation and / or flow of the molten material. The welding process can be a laser welding process. The welding process can involve welding two elongated conductors arranged side by side. In particular, the two elongated conductors arranged side by side can be joined to each other in sections where their cladding has been removed and the oxide layer has been formed.

[0015] The oxide layer can be an aluminum oxide layer. The oxide layer can have a thickness of, for example, 5 μm to 25 μm, particularly 10 μm to 20 μm.

[0016] The segment may be an end segment. The segment may be located at one end of an elongated conductor.

[0017] The laser beam can be a laser beam focused on that section of a slender conductor. The laser beam can be guided by means of a scanner optical unit or a beam guiding element, such as an optical fiber cable.

[0018] The laser beam can have a beam quality factor (M) less than or equal to 2, particularly in the range of 1 to 1.4. 2 Alternatively, the laser beam can have a beam quality factor M greater than 4. 2 Preferably, the laser beam can have a Gaussian intensity distribution. Alternatively, the laser beam can be a multimode laser beam, and preferably has a plateau-shaped intensity distribution across its cross-section. This is also referred to by those skilled in the art as a cap intensity distribution. This allows for particularly efficient removal of the coating and / or heating of the conductive core.

[0019] The laser beam can have a wavelength of 800 nm to 1200 nm, particularly 1030 nm, 1064 nm, or 1070 nm. Alternatively, the laser beam can have a wavelength of 500 nm to 550 nm, particularly 515 nm. Alternatively, the laser beam can have a wavelength of 300 nm to 380 nm, preferably in the range of 355 nm to 357 nm, or 343 nm.

[0020] The laser beam can be a continuous wave laser beam or a pulsed laser beam.

[0021] The cross-section of a laser beam can have a symmetrical or asymmetrical intensity distribution relative to its center point. The long extension dimension of the laser beam's cross-section is 1.1 to 10 times its short extension dimension. For example, the cross-section of a laser beam can have a cap-shaped intensity distribution on its long extension dimension and a Gaussian intensity distribution on its short extension dimension.

[0022] A laser beam can be a multifocal laser beam. A multifocal laser beam can be understood as having multiple spots in its focal aspect, specifically having at least two or four spots.

[0023] Removing the coating and heating the section can be done simultaneously or sequentially. The coating can be removed mechanically.

[0024] Heating of the section by irradiating it with a laser beam can be achieved by the laser beam passing over the section once or multiple times.

[0025] Heating of the section can be achieved by irradiating it with a laser beam by scanning the section with the laser beam. The scanning may involve scanning the section point by point with the laser beam along parallel, staggered lines.

[0026] For example, a scanner optics unit can be used to illuminate the section with a laser beam. In particular, the scanner optics unit can be configured to point the laser beam at the section and / or guide the laser beam through the section.

[0027] The heating can be performed in such a way that a uniform and / or consistent oxide layer is formed. In particular, defects in the existing oxide layer, such as scratches or inclusions, can be removed by heating.

[0028] Heating can be performed in such a way that the thickness of the existing oxide layer is increased by at least 10%, preferably by 20%.

[0029] Heating can be performed at a temperature of at least 80°C, particularly at a temperature of 80°C to 90°C. This temperature range is particularly advantageous for the formation of the oxide layer.

[0030] In an extended version of this method, the energy density of the laser beam, particularly the total energy density, is 1 J / cm². 2 Up to 40J / cm 2 In particular, the energy density of the laser beam can be 1 J / cm². 2 Up to 15 J / cm 2 6 J / cm 2 Up to 15 J / cm 2 6 J / cm 2 Up to 8 J / cm 2 Such an energy density of a laser beam is particularly advantageous for the formation of an oxide layer. In particular, with such an energy density of the laser beam, an oxide layer can be formed so that the oxide layer helps the molten material generated during the welding process.

[0031] In an extended version of this method, the coating removal is performed by irradiating the segment with a laser beam. Advantageously, using a laser beam to remove the coating simplifies the implementation of this method.

[0032] In an extended version of this method, the removal of the coating and the heating of the conductive core are performed by a single pass of the laser beam over the section. Alternatively, the coating is removed and the conductive core is heated by multiple passes of the laser beam over the section, such as two or three passes.

[0033] For example, the first pass of the laser beam over the section removes the coating, and the second pass of the laser beam over the section heats the conductive core. In an alternative example, the first and second passes of the laser beam over the section remove the coating, and the third pass of the laser beam over the section heats the conductive core.

[0034] In an extended version of the method, the method includes the step of cleaning the segment by irradiating it with a laser beam to remove contaminants. Cleaning the segment allows for the formation of a particularly uniform and defect-free oxide layer. Cleaning the segment and heating the conductive core can be performed simultaneously, particularly using a single pass of the laser beam across the segment; or they can be performed separately in time, particularly using two passes of the laser beam across the segment. Contaminants may include, for example, coating residues, soot, and / or dirt.

[0035] For example, in the first step, the coating can be irradiated with a laser beam to remove it by ablation. Subsequently, in the second step, the section can be heated by irradiating it with a laser beam. Specifically, the ablation of the coating in the first step can be performed by passing the laser beam across the section once or twice. If a two-pass ablation is used, the laser beam can regionally remove the coating in the section during the first pass by localized ablation, leaving residual grids of the coating after the first pass. In a subsequent second pass across the section, the laser beam removes the residual grids of the coating by ablation. Additionally, in the second step using laser beam heating, any remaining coating residue in the section can be simultaneously cleaned by the laser beam.

[0036] In an alternative example, the coating can be pre-destructed during the first pass of the laser beam over the section. For example, pre-destruction can be achieved by carbonizing the coating. Carbonization of the coating can, for example, involve the formation of absorption centers within the coating. During the second pass of the laser beam over the section, the coating can be removed by the absorption of the laser beam at the pre-destruction area. In particular, the coating can be removed by burning it off with the laser beam during the second pass. During the third pass of the laser beam over the section, the section can be irradiated to heat it and form an oxide layer. Specifically, smoke from the section can be simultaneously cleared during the third pass.

[0037] In an extended embodiment of the method, the method includes the step of removing an existing oxide layer in the segment by irradiating the segment with a laser beam. The formation of the oxide layer is the formation of a new oxide layer. Advantageously, this allows the non-uniform and / or defective existing oxide layer to be replaced by a uniform and / or defect-free new oxide layer. Defects may include, for example, scratches or inclusions in the oxide layer. Additionally, the new oxide layer may be thicker than the previously removed existing oxide layer.

[0038] The removal of the existing oxide layer can be performed simultaneously with the removal of the coating. Alternatively, the existing oxide layer can be removed either before or during the heating of the conductive core.

[0039] The removal of existing oxide layers and the heating of conductive cores can be performed using the same or different beam parameters of a laser beam.

[0040] In an extended version of the method, the method includes the step of blowing the section with an oxidant, particularly a gaseous oxidant. Advantageously, the formation of an oxide layer can be supported by blowing the section with an oxidant. In particular, the formation of the oxide layer can be controlled by controlling the blowing of the oxidant. For example, the flow rate of the oxidant during blowing can be varied to control the formation of the oxide layer.

[0041] An oxidizing agent can be suitable to support the formation of the oxide layer. For example, the oxidizing agent can be oxygen. The blowing of this section and the heating of the conductive core for forming the oxide layer can occur simultaneously or sequentially. In particular, the blowing of this section can occur after the conductive core is heated.

[0042] In an extended version of this method, the laser beam has a Gaussian or cap-shaped intensity distribution across its cross-section. The cap-shaped intensity distribution can be a uniform intensity distribution, which, in particular, produces a highly consistent removal of the cladding and / or heating of the conductive core across the cross-section of the laser beam.

[0043] The intensity distribution of the top cap shape can be circular, elliptical, square, or rectangular.

[0044] In an extended version of this method, the laser beam is a pulsed laser beam. Advantageously, the pulsed laser beam achieves high peak intensity at moderate average power, making targeted heat input to the surface of this section possible. This prevents damage to the cladding located outside this section. The laser pulses of the pulsed laser beam can have pulse lengths in the picosecond or nanosecond range, particularly in the range of 1 picosecond to 950 nanoseconds. The pulse repetition rate of the pulsed laser beam can be in the range of 1 kHz to 4 MHz.

[0045] In an extended version of this method, the irradiation of the segment is performed such that the area irradiated by one laser pulse overlaps or does not overlap with the area irradiated by the next laser pulse following that pulse. If the laser pulses overlap, positive pulse overlap occurs. If the laser pulses do not overlap, negative pulse overlap occurs. Here, for example, in the case of positive pulse overlap, multiple temporally successive irradiations of the same surface segment of the segment can be a second pass.

[0046] The machine tool according to the invention is configured to perform the above-described method.

[0047] In particular, the machine tool can have the following variations for performing the method according to the invention: Variant 1: A laser and an optical unit for beam guiding and using point laser radiation; Variant 2: A laser and an optical unit for beam guiding and using multifocal laser radiation; Variant 3: More than one laser and an optical unit for beam guiding and using point laser radiation; Variant 4: More than one laser and an optical unit for beam guiding and using multifocal laser radiation; Variant 5: More than one laser and more than one optical unit for beam guiding and using multifocal laser radiation. Attached Figure Description

[0048] Further advantages and advantageous configurations of the invention can be derived from the drawings, its description, and the claims. All features disclosed in the drawings, its description, and the claims, in themselves and in any desired combination thereof, are essential to the invention. In the drawings: Figure 1 A schematic representation of an elongated conductor with a coating during the removal of the coating using a laser beam is shown; Figure 2 It shows the illumination with a laser beam. Figure 1 A schematic representation of the overlapping regions of a slender conductor; Figure 3 Showing from Figure 1 A schematic representation of the possible cross-section of a laser beam; Figure 4 A schematic representation of an elongated conductor with a coating during the removal of the coating with a laser beam, according to another embodiment, is shown; Figure 5 This shows the result after the coating was removed. Figure 1 A schematic representation of the cross-section of a segment of a slender conductor; Figure 6This shows the process of heating to form an oxide layer. Figure 1 A schematic representation of a slender conductor; and Figure 7 This shows the process after the formation of the oxide layer. Figure 5 A schematic representation of the cross-section. Detailed Implementation

[0049] The accompanying drawing illustrates a process for pretreating an elongated conductor 10 for use in a welding process. The purpose of this method is to form an oxide layer adapted to prevent unwanted runoff and / or flow away from the weld area by molten material generated during the welding process. Advantageously, due to the oxide layer formed during the welding process, shape-stable molten beads can be formed, resulting in a higher quality weld joint produced by the welding process.

[0050] exist Figure 1 In the image, the elongated conductor 10 is shown as a conductive element. The elongated conductor 10 has a conductive core 12 and a cladding 14.

[0051] The core 12 is radially surrounded outward by a cladding 14. The cladding 14 serves as an electrical insulator for the core 12 relative to the environment in the radial direction. The cladding 14 is made of polyamide-imide. The cladding has a dielectric strength of 45 kV / mm.

[0052] Core 12 has a rectangular cross-section. However, other cross-sectional shapes are also conceivable, such as an octagonal or circular cross-section. The side length of the rectangular cross-section can be, for example, from 0.2 mm to 15 mm, preferably from 2 mm to 8 mm.

[0053] Core 12 comprises aluminum. In other words, core 12 is made of an aluminum alloy. In the illustrated embodiment, core 12 is made of material EN AW-1050A.

[0054] Elongated conductor elements 10 are adapted to be arranged in an electric motor to form the stator of the motor. For this purpose, if multiple identical elongated conductor elements 10 are arranged in a stator configuration, the multiple identical elongated conductor elements can be electrically connected to each other to form the stator. The electrical connection of the elongated conductor elements 10 is typically achieved by welding the elongated conductor elements 10 together.

[0055] Figure 1 The elongated conductor 10 shown is designed as a hair clip. For clarity, in Figure 1 Only a portion of the elongated conductor 10 is shown in the image.

[0056] Figure 1 A machine tool 16 configured to perform a method for preprocessing an elongated conductor 10 is shown. The machine tool 16 is configured to generate a laser beam 18 and focus it on a segment 20 of the elongated conductor 10.

[0057] Segment 20 is the end segment of the elongated conductor 10. In other words, segment 20 is located at end 22 of the elongated conductor 10. The length of segment 20 can be, for example, 0.5 cm to 5 cm, particularly 1 cm to 3 cm. The length of segment 20 can be measured from end 22 parallel to the longitudinal axis of the elongated conductor 10. In the illustrated embodiment, the length of segment 20 is 3 cm.

[0058] The coating 14 in section 20 is removed by irradiating section 20 with laser beam 18.

[0059] exist Figure 1 In the illustrated embodiment, machine tool 16 provides a beam quality factor M of 1.3. 2 A laser beam 18 is used, which has a Gaussian intensity distribution in its cross-section. The laser beam 18 has a wavelength of 1030 nm. The laser beam 18 is pulsed. The pulse length of the pulsed laser beam 18 is in the picosecond range, and the pulse repetition frequency of the pulsed laser beam 18 is 1 MHz. The parameters of the laser beam 18 are adjusted according to the material of the coating 14, so that the laser beam 18 removes the coating 14.

[0060] Figure 1 The diagram illustrates the removal of the coating 14 in segment 20 by irradiating segment 20 with a laser beam 18. For this purpose, segment 20 is scanned with the laser beam 18. In other words, segment 20 is scanned point-by-point by the laser beam 18 along parallel and staggered lines. Irradiation of segment 20 can be performed such that the area 24 irradiated by one laser pulse and the area 26 irradiated by the next laser pulse following that pulse may or may not overlap. For example, Figure 2 a shows the overlap of two irradiated areas 24 and 26, while Figure 2 b shows that the two irradiated areas 24 and 26 do not overlap. This produces Figure 2 Positive pulse overlap in a and Figure 2 The negative pulses in b overlap.

[0061] exist Figure 1 In the illustrated embodiment, segment 20 is irradiated to cause negative pulse overlap. The energy density, particularly the total energy density, of the laser beam 18 used to remove the coating can be, for example, 6 J / cm². 2 Up to 8 J / cm 2 .exist Figure 1 In the embodiment shown, the energy density of the laser beam 18 is 6.5 J / cm². 2 .

[0062] This allows the cladding to be removed by peeling in each irradiated area 24, 26. After the laser beam 18 passes over section 20 for the first time, a residual grid of cladding 14 remains. This residual grid is removed as the laser beam 18 passes over section 20 a second time. Therefore, cladding 14 is completely removed from section 20. In other words, cladding 14 is completely removed from the elongated conductor 10 within section 20. In other words, cladding 14 is completely removed from the elongated conductor 10 around its perimeter within section 20.

[0063] because Figure 1 The machine tool 16 is shown during the removal of the coating 14, therefore in Figure 1 In the middle, the cladding layer 14 in region 20 has not yet been completely removed.

[0064] In alternative embodiments not shown, the coating can be removed using a laser beam having a cap intensity distribution on its cross-section and / or having a circular, elliptical, square, or rectangular shape. Figure 3 Different shapes are shown here. Figure 3 a shows a circular shape, Figure 3 b shows an elliptical shape. Figure 3 c shows a square shape, and Figure 3 d shows a rectangular shape. Specifically, from... Figure 3 c and Figure 3 As can be seen from d, square and rectangular shapes have rounded corners. However, this is not mandatory.

[0065] Figure 4 Showing from Figure 1 In another embodiment, the same reference numerals are used for the same and functionally equivalent elements, and in this respect, reference may be made to the above regarding... Figure 1 The embodiments are given in the description, so basically only the differences that exist are discussed.

[0066] exist Figure 4 In the initial example, the material of the coating 14 is polyetheretherketone (PEEK). During the first pass of the laser beam 18 over segment 20, the coating 14 is pre-destructed. Pre-destruction includes the formation of carbonization sites 28 in the coating. The carbonization sites 28 form absorption centers in the coating, where the laser beam is particularly well absorbed during the second pass of the laser beam over segment 20. Therefore, during the second pass of the laser beam 18 over segment 20, removal of the coating occurs by means of the absorption of the laser beam 18 at the carbonization sites 28. Here, the coating 14 is burned off by the laser beam 18.

[0067] Regardless of whether the coating 14 is based on Figure 1 The embodiments are still based on Figure 4In embodiments where the coating 14 is removed, the section 20 can be cleaned of contaminants by irradiating it with a laser beam 18. Contaminants may include, for example, coating residue, soot, and / or dirt. However, cleaning the section 20 is not mandatory.

[0068] Figure 5 A cross-sectional view of the core 12 in segment 20 after the cladding 14 has been removed is shown. Figure 5 The surface of core 12, particularly its peripheral side surface, is shown, formed of an oxide layer 30. The oxide layer 30 is a conventional oxide layer formed of aluminum oxide. The conventional oxide layer 30 has scratches 32 and inclusions 34. The thickness 36 of the conventional oxide layer 30 is less than 5 µm. Therefore, the conventional oxide layer 30 is not suitable for preventing unwanted runoff and / or flow-away of molten material generated during the welding process from the weld area.

[0069] Figure 6 This illustrates the process of heating the conductive core 12 by irradiating section 20 with laser beam 18 to form an oxide layer 38 within section 20. Figure 1 The elongated conductor 10. For this purpose, the conductive core 12 is scanned with a laser beam 18.

[0070] The conductive core 12 is heated to a temperature of at least 80°C, for example, 85°C. At such a temperature, the aluminum of the conductive core 12 reacts with oxygen from the environment to form a uniform and / or consistent oxide layer 38.

[0071] The energy density, particularly the total energy density, of the laser beam 18 used to heat the conductive core 12 can be, for example, 10 J / cm². 2 Up to 20 J / cm 2 .exist Figure 6 In the embodiment shown, the energy density of the laser beam 18 is 15 J / cm². 2 .

[0072] In particular, targeted heat input is achieved on the surface of section 20 by pulsed laser beam 18, which prevents the cladding 14 located outside section 20 from being damaged, for example, by the heated conductive core 12.

[0073] By irradiating section 20 with laser beam 18, the existing oxide layer 30 is removed, and simultaneously the conductive core 12 is heated. As a result of the heating, an oxide layer 38 is formed on the surface of the conductive core 12. The formation of oxide layer 38 is the formation of a new oxide layer 38. In other words, the existing oxide layer 30 with scratches 32 and inclusions 34 is replaced by the new oxide layer 38.

[0074] Figure 7A cross-sectional view of the core 12 in section 20 after heating the conductive core 12 is shown. A new oxide layer 38 is formed on the surface of the conductive core 12. The new oxide layer 38 is an oxide layer formed of aluminum oxide. The new oxide layer 38 is free of scratches or inclusions. The thickness 40 of the new oxide layer 38 is 20 µm. This means that the new oxide layer 38 is thicker than the previously removed existing oxide layer 30. The new oxide layer 38 is adapted to prevent unwanted runoff and / or flow away from the weld area of ​​molten material generated during the welding process.

[0075] In an alternative embodiment not shown, the method includes the step of blowing the section with an oxidant in the form of oxygen, particularly a gaseous oxidant. The blowing may occur simultaneously with irradiating the section with a laser beam.

Claims

1. A method for pretreating elongated conductors (10) for use in a welding process, wherein, The elongated conductor (10) has a conductive core (12) and a cladding (14), wherein the core (12) comprises aluminum, and the method includes the following steps: - Remove the cladding (14) within a section (20) of the elongated conductor (10). - The conductive core (12) is heated by irradiating the segment (20) with a laser beam (18) to form an oxide layer (38) within the segment (20).

2. The method according to claim 1, - Wherein, the energy density of the laser beam (18) is 1 J / cm 2 Up to 40 J / cm 2 .

3. The method according to any one of the preceding claims, - The removal of the coating (14) is performed by irradiating the segment (20) with the laser beam (18).

4. The method according to any one of the preceding claims, - in, The removal of the coating (14) and the heating of the conductive core (12) are performed by means of the laser beam (18) passing through the section (20) in a single pass, or - In this process, the removal of the coating (14) and the heating of the conductive core (12) are performed by means of the laser beam (18) passing over the section (20) multiple times.

5. The method according to any one of the preceding claims, the method comprising the following steps: - The dirt in the section (20) is cleaned by irradiating the section (20) with the laser beam (18).

6. The method according to any one of the preceding claims, the method comprising the following steps: - Remove the existing oxide layer (30) within the segment (20) by irradiating the segment (20) with the laser beam (18). - Wherein, the formation of the oxide layer (38) refers to the formation of a new oxide layer (38).

7. The method according to any one of the preceding claims, the method comprising the following steps: - Blow the section (20) with an oxidant, especially a gaseous oxidant.

8. The method according to any one of the preceding claims, - Wherein, the laser beam (18) has a Gaussian or top-hat-shaped intensity distribution in the cross-section of the laser beam.

9. The method according to any one of the preceding claims, - in, The laser beam (18) is a pulsed laser beam (18).

10. The method according to claim 9, - The irradiation of the section (20) is performed in such a way that the area (24) irradiated by a laser pulse overlaps or does not overlap with the area (26) irradiated by the next laser pulse following the laser pulse.

11. A machine tool (16), - in, The machine tool (16) is configured to perform the method according to any one of the preceding claims.

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