Method for preparing an elongate conductor element for a welding process, and machine tool for carrying out the method

Abstract

The invention relates to a method for preparing an elongate conductor element (10) for a welding process, wherein the elongate conductor element (10) has an electrically conductive core (12) and a coating (14), and the core (12) contains aluminum, the method comprising the steps: removing the coating (14) within a portion (20) of the elongate conductor element (10), and heating the electrically conductive core (12) by irradiating the portion (20) with a laser beam (18) in order to form an oxide layer (38) within the portion (20).

Description

[0001] Method for preparing an elongated conductor piece for a welding process and machine tool for carrying out the method

[0002] Description

[0003] The invention relates to a device and a method for preparing an elongated conductor piece for a welding process and a machine tool.

[0004] DE 10 2020 212 087 A1 describes a method for removing an electrically non-conductive plastic coating from an electrically conductive metal core of a conductor. The plastic coating is removed by repeatedly irradiating the plastic coating with laser radiation.

[0005] The object of the present invention is to provide a method for preparing an elongated conductor piece for a welding process, which method has improved properties, in particular, which better prepares the elongated conductor piece for the welding process. Furthermore, the object of the present invention is to provide a machine tool designed to carry out such a method.

[0006] The invention solves this problem by providing a method having the features of claim 1 and a machine tool having the features of claim 11. Advantageous developments and / or embodiments of the invention are described in the dependent claims.

[0007] A method according to the invention is designed for preparing an elongated conductor piece for a welding process. The elongated conductor piece has an electrically conductive core and a coating. The core contains aluminum. The method comprises the steps of removing the coating in a portion of the elongated conductor piece, and heating the electrically conductive core by irradiating the portion with a laser beam for the purpose of forming an oxide layer in the portion.

[0008] By forming the oxide layer, it can advantageously be achieved that during a subsequent welding process in which the section is melted at least in part, a forming melt is better held in position by the oxide layer. In other words, the formed oxide layer can prevent unwanted flowing and / or running of the melt created during the welding process from a welding area. In other words, the formed oxide layer can support the melt created during the welding process, thereby preventing, in particular, unwanted flowing away of the melt. For this purpose, the oxide layer can float on the melt during the welding process. Consequently, the oxide layer can enable the formation of a stable melt droplet during a subsequent welding process and thus, for example, prevent unwanted contact between the coating and the melt.In particular, due to the oxide layer's supporting function for the melt during the welding process, a higher quality of the welded joint produced by the welding process can be achieved. Thus, the method according to the invention advantageously enables better preparation of the elongated conductor piece for the welding process.

[0009] Preparation can be understood in particular as preparing the elongated conductor piece for the welding process.

[0010] The elongated conductor piece can be referred to as an electrically conductive element, in particular the elongated conductor piece can be designed as an electrically conductive element.

[0011] The elongated conductor piece may be suitable for arrangement in an electrical machine, for example in the form of an electric motor, to form a stator of the electrical machine. A plurality of the elongated conductor pieces, when arranged in a stator and electrically connected to one another, can be used to generate a magnetic field required for the operation of the electrical machine. The electrical connection of the plurality of elongated conductor pieces to one another can be achieved by means of a welding process.

[0012] The elongated conductor piece can be designed as a hairpin, in particular, the elongated conductor piece can be a hairpin. The hairpin can have two elongated, in particular parallel, legs that are connected to each other by a connecting section. One form of the hairpin can be hairpin-shaped. In other words, a hairpin can have a U-shape. Alternatively, the elongated conductor piece can be designed as a special pin. The special pin can have one, in particular a single, leg. The elongated conductor piece can also be a combination of a hairpin and a special pin.

[0013] The elongated conductor section can have a rectangular cross-section. In particular, the core can have a rectangular cross-section. The elongated conductor section can be designed as a rod-shaped conductor with a rectangular cross-section. An edge length of the elongated conductor section can be between 0.2 mm and 15 mm, preferably between 2 mm and 8 mm.

[0014] The coating can surround the core in the radial direction, in particular outwards. The coating can be an electrical insulator. In particular, the coating can electrically insulate the core from its surroundings. The coating can have a dielectric strength of 20 to 60 kV / mm. The coating can be a varnish. The coating can preferably be made of polyamide-imide (abbreviation: PAI), polyetheretherketone (abbreviation: PEEK), or a combination of polyamide-imide and polyimide film (abbreviation: PAI + FEP). The coating can be a single-layer coating or a multi-layer coating. For example, the coating can comprise a layer of polyamide-imide and a further layer of polyetherketone. The coating can be transparent to visible light.

[0015] An aluminum-containing core can be understood as meaning that the core is formed from, or in particular consists of, an aluminum alloy. Preferably, the aluminum-containing core can be formed from an aluminum-based alloy with at least 75%, 80%, 90%, 95%, or 98% aluminum by weight. The core can be made from, or in particular consist of, aluminum. For example, the aluminum-containing core can be formed from the material EN AW-1050A.

[0016] The oxide layer can be suitable for stabilizing a melt formed during the welding process. In particular, the oxide layer can be suitable for preventing the melt from accidentally leaving and / or running. The welding process can be a laser welding process. The welding process can comprise welding two elongated conductor pieces arranged side by side. In particular, the two elongated conductor pieces arranged side by side can be welded together in their sections in which the coating was removed and the oxide layer was formed. The oxide layer can be an aluminum oxide layer. The oxide layer can, for example, have a thickness of 5 μm to 25 μm, in particular 10 μm to 20 μm.

[0017] The section may be an end section. The section may be located at one end of the elongated conductor section.

[0018] The laser beam can be a laser beam focused on the section of the elongated conductor. The laser beam can be guided by means of a scanner optics or a beam guiding element, for example, a fiber optic cable.

[0019] The laser beam can have a diffraction coefficient M 2 of equal to or less than 2, in particular in the range from 1 to 1.4. Alternatively, the laser beam may have a diffraction index M 2 of greater than 4. The laser beam can preferably have a Gaussian intensity profile. Alternatively, the laser beam can be a multimode laser beam and preferably have a plateau-shaped intensity distribution across its cross-section. Those skilled in the art also refer to this as a so-called top-hat intensity profile. This allows for particularly effective removal of the coating and / or heating of the electrically conductive core.

[0020] The laser beam can have a wavelength of 800 nm to 1200 nm, in particular 1030 nm, 1064 nm, or 1070 nm. Alternatively, the laser beam can have a wavelength of 500 nm to 550 nm, in particular 515 nm. Alternatively, the laser beam can have a wavelength of 300 nm to 380 nm, preferably 355 nm to 357 nm or 343 nm.

[0021] The laser beam can be a continuous wave laser beam or a pulsed laser beam.

[0022] A cross-section of the laser beam can have a symmetrical or asymmetrical intensity distribution relative to a center point of the laser beam. The cross-section of the laser beam can be 1.1 to 10 times larger in its long extension than in its short extension. For example, the cross-section of the laser beam can have a top-hat-shaped intensity profile in its long extension and a Gaussian intensity profile in its short extension. The laser beam can be a multi-focal laser beam. A multi-focal laser beam can be understood as having a plurality, in particular at least two or four, spots at its focus.

[0023] The coating removal and heating of the section can be performed simultaneously or sequentially. The coating removal can be performed mechanically.

[0024] Heating by irradiating the section with the laser beam can be done by a single pass or multiple passes of the laser beam over the section.

[0025] Heating by irradiating the section with the laser beam can be achieved by scanning the section with the laser beam. The scanning can be performed by scanning the section point by point and along parallel, offset lines with the laser beam.

[0026] For example, the laser beam can be irradiated onto the section using a scanner optics system. In particular, the scanner optics system can be configured to direct the laser beam onto the section and / or to guide the laser beam over the section.

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

[0028] The heating can be carried out in such a way that an existing oxide layer increases in thickness by at least 10%, preferably 20%.

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

[0030] In a further development of the method, a fluence, in particular a total fluence, of the laser beam is 1 J / cm 2 up to 40 J / cm 2 In particular, the fluence of the laser beam can be 1 J / cm 2 up to 15 J / cm 2 , 6 J / cm 2 up to 15 J / cm 2 , 6 J / cm 2up to 8 J / cm 2 Such a laser beam fluence can be particularly advantageous for the formation of the oxide layer. In particular, with such a laser beam fluence, the oxide layer can be formed in such a way that it supports the melt produced during the welding process.

[0031] In a further development of the method, the coating is removed by irradiating the section with a laser beam. Advantageously, the use of the laser beam for removing the coating can simplify implementation of the method.

[0032] In a further development of the method, the coating is removed and the electrically conductive core is heated by a single pass of the laser beam over the section. Alternatively, the coating is removed and the electrically conductive core is heated by a plurality of passes, for example, two or three, of the laser beam over the section.

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

[0034] In a further development of the method, the method comprises the step of cleaning the section of contaminants by irradiating the section with the laser beam. Cleaning the section can enable a particularly homogeneous and defect-free formation of the oxide layer. Cleaning the section and heating the electrically conductive core can occur simultaneously, in particular with a single pass of the laser beam over the section, or separated in time, in particular with two passes of the laser beam over the section. Contaminants can be, for example, coating residues, smoke, and / or dirt.

[0035] For example, in a first step the coating can be irradiated with the laser beam in such a way that it is removed by chipping. Then in a second step the section can be heated by irradiating it with a laser beam. In particular the chipping of the coating in the first step can take place by means of one pass or two passes of the laser beam over the section. If the coating is chipped off by means of two passes the laser beam can remove the coating in part of the section in a first pass by locally chipping off the coating so that a residual grid of the coating remains after completion of the first pass. In a subsequent second pass of the laser beam over the section the laser beam can remove the residual grid of the coating by chipping.In addition, during the heating of the second step by means of the laser beam, the section can be cleaned of residues of the coating by the laser beam at the same time.

[0036] In an alternative example, the coating can be pre-damaged during a first pass of the laser beam over the section. The pre-damage can, for example, be carbonization of the coating. The carbonization of the coating can, for example, be the formation of absorption centers in the coating. During a second pass of the laser beam over the section, the coating can be removed by absorption of the laser beam at the pre-damage. In particular, the coating can be ablated during the second pass by burning off using the laser beam. During a third pass of the laser beam over the section, the section can be irradiated in such a way that the section is heated for the purpose of forming the oxide layer. In particular, during the third pass, the section can be cleaned of soot at the same time.

[0037] In a further development of the method, the method comprises the step of removing an existing oxide layer in the section by irradiating the section with the laser beam. The formation of the oxide layer is a formation of a new oxide layer. Advantageously, the existing oxide layer, which is, for example, inhomogeneous and / or has defects, can thereby be replaced by the new oxide layer, which is, for example, homogeneous and / or has no defects. Defects can be, for example, scratches or inclusions in the oxide layer. In addition, the new oxide layer can be thicker than the previously removed existing oxide layer. The removal of the existing oxide layer can take place simultaneously with the removal of the coating. Alternatively, the removal of the existing oxide layer can take place before or simultaneously with the heating of the electrically conductive core.

[0038] The removal of the existing oxide layer and the heating of the electrically conductive core can be carried out with the same or different beam parameters of the laser beam.

[0039] In a further development of the method, the method comprises the step of flowing an oxidizing agent, in particular a gaseous one, over the section. Advantageously, the formation of the oxide layer can be assisted by flowing the oxidizing agent over the section. In particular, the formation of the oxide layer can be controlled by controlling the flow of the oxidizing agent. For example, a flow velocity of the oxidizing agent can be changed during the flow for the purpose of controlling the formation of the oxide layer.

[0040] The oxidizing agent may be suitable for assisting the formation of the oxide layer. For example, the oxidizing agent may be oxygen. The flow over the section and the heating of the electrically conductive core to form the oxide layer may occur simultaneously or sequentially. In particular, the flow over the section may occur after heating the electrically conductive core.

[0041] In a further development of the method, the laser beam has a Gaussian or top-hat-shaped intensity distribution in its cross-section. The top-hat-shaped intensity distribution can be a homogeneous intensity distribution, which in particular enables particularly uniform removal of the coating and / or heating of the electrically conductive core across the cross-section of the laser beam.

[0042] The top-hat-shaped intensity distribution can have a circular, elliptical, square or rectangular shape.

[0043] In a further development of the method, the laser beam is a pulsed laser beam. Advantageously, the pulsed laser beam achieves high peak intensities at moderate average power levels, enabling targeted heat input to the surface of the section. This can prevent damage to the coating outside the section. A laser pulse of the pulsed laser beam can have a pulse duration in the picosecond range or in the nanosecond range, in particular in the range from 1 picosecond to 950 nanoseconds. The pulse repetition frequency or repetition rate of the pulsed laser beam can be between 1 kHz and 4 MHz.

[0044] In a further development of the method, the section is irradiated in such a way that a region irradiated with a laser pulse and a region irradiated with a laser pulse following the laser pulse either overlap or do not overlap. If the laser pulses overlap, a positive pulse overlap can occur. If the laser pulses do not overlap, a negative pulse overlap can occur. In this case, a temporally consecutive, multiple irradiation of the same surface section of the section, for example, in the case of a positive pulse overlap, can constitute a second pass.

[0045] A machine tool according to the invention is designed to carry out a method described above.

[0046] The machine tool can have in particular the following variants for carrying out the method according to the invention:

[0047] Variant 1: One laser and one optic for beam guidance and use of spot laser radiation; Variant 2: One laser and one optic for beam guidance and use of multi-focal laser radiation;

[0048] Variant 3: More than one laser and one optics for beam guidance and use of spot laser radiation;

[0049] Variant 4: More than one laser and one optics for beam guidance and use of multifocal laser radiation;

[0050] Variant 5: More than one laser and more than one optics for beam guidance and use of multi-focal laser radiation.

[0051] Further advantages and advantageous embodiments of the invention can be gathered from the figures, their description, and the claims. All features disclosed in the figures, their description, and the claims can be essential to the invention both individually and in any combination. They show: Fig. 1 is a schematic representation of an elongated conductor section with a coating during the removal of the coating with a laser beam.

[0052] Fig. 2 is a schematic representation of an overlap of a region of the elongated conductor piece of Fig. 1 irradiated with the laser beam,

[0053] Fig. 3 is a schematic representation of possible cross sections of the laser beam of Fig. 1 ,

[0054] Fig. 4 is a schematic representation of an elongated conductor piece with a coating during removal of the coating with a laser beam according to another embodiment,

[0055] Fig. 5 is a schematic representation of a cross-section of a portion of the elongated conductor piece of Fig. 1 after removal of the coating,

[0056] Fig. 6 is a schematic representation of the elongated conductor piece of Fig. 1 during heating for the purpose of forming an oxide layer, and

[0057] Fig. 7 is a schematic representation of the cross section of Fig. 5 after the formation of an oxide layer.

[0058] The figures illustrate a process for preparing an elongated conductor section 10 for a welding process. The goal of the process is to form an oxide layer suitable for preventing unwanted flow and / or runoff of the molten metal produced during the welding process from a welding area. Advantageously, the formed oxide layer allows a dimensionally stable molten metal bead to form during the welding process, thereby achieving a higher quality of the welded joint produced by the welding process.

[0059] Fig. 1 shows the elongated conductor section 10 in the form of an electrically conductive element. The elongated conductor section 10 has an electrically conductive core 12 and a coating 14. The core 12 is surrounded by the coating 14 in a radial outward direction. The coating 14 acts as electrical insulation of the core 12 in the radial direction from the surroundings. The material of the coating 14 is polyamide-imide. The coating has a dielectric strength of 45 kV / mm.

[0060] The core 12 has a rectangular cross-section. However, other cross-section shapes are also conceivable, such as an octagonal cross-section or a round cross-section. The edge length of the rectangular cross-section can be, for example, 0.2 mm to 15 mm, preferably 2 mm to 8 mm.

[0061] The core 12 contains aluminum. In other words, the core 12 is made of an aluminum alloy. In the illustrated embodiment, the core 12 is made of the material EN AW-1050A.

[0062] The elongated conductor piece 10 is suitable for arrangement in an electrical machine to form a stator of the electrical machine. For this purpose, several identically constructed elongated conductor pieces 10, when arranged in a stator configuration, can be electrically connected to one another to form the stator. The electrical connection of the elongated conductor pieces 10 is typically achieved by welding the elongated conductor pieces 10 together.

[0063] The elongated conductor section 10 shown in Fig. 1 is designed as a hairpin. For reasons of clarity, the elongated conductor section 10 is only partially shown in Fig. 1.

[0064] Fig. 1 shows a machine tool 16 configured to perform the method for preparing the elongated conductor piece 10. The machine tool 16 is configured to generate a laser beam 18 and focus it onto a portion 20 of the elongated conductor piece 10.

[0065] The section 20 is an end section of the elongated conductor piece 10. In other words, the section 20 is arranged at an end 22 of the elongated conductor piece 10. A length of the section 20 can be, for example, 0.5 cm to 5 cm, in particular 1 cm to 3 cm. The length of the section 20 can be measured from the end 22 parallel to a longitudinal axis of the elongated conductor piece 10. In the illustrated embodiment, the length of the section 20 is 3 cm. The coating 14 is removed in the section 20 by irradiating the section 20 with the laser beam 18.

[0066] In the illustrated embodiment of Fig. 1, the machine tool 16 provides the laser beam 18 with a diffraction coefficient M 2 of 1.3, which exhibits a gaseous intensity profile in its cross-section. The laser beam 18 has a wavelength of 1030 nm. The laser beam 18 is pulsed. The pulse duration 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 matched to the material of the coating 14 such that the laser beam 18 removes the coating 14.

[0067] Fig. 1 shows that the coating 14 in the section 20 is removed by irradiating the section 20 with the laser beam 18. For this purpose, the section 20 is scanned with the laser beam 18. In other words, the section 20 is scanned point by point by the laser beam 18 along lines that run parallel and offset to one another. The irradiation of the section 20 can occur in such a way that a region 24 irradiated with a laser pulse and a region 26 irradiated with a laser pulse following the laser pulse overlap or do not overlap. For example, Fig. 2a shows that the two irradiated regions 24, 26 overlap, and Fig. 2b shows that the two irradiated regions 24, 26 do not overlap. Thus, a positive pulse overlap occurs in Fig. 2a and a negative pulse overlap in Fig. 2b.

[0068] In the embodiment of Fig. 1, the section 20 is irradiated such that a negative pulse overlap occurs. A fluence, in particular a total fluence, of the laser beam 18 for removing the coating can be, for example, 6 J / cm 2 up to 8 J / cm 2 In the embodiment of Fig. 1, the fluence of the laser beam 18 is 6.5 J / cm 2 .

[0069] As a result, the coating in each irradiated area 24, 26 is removed by chipping. After a first pass of the laser beam 18 over the section 20, a residual grid of the coating 14 remains. This residual grid is removed by a second pass of the laser beam 18 over the section 20. As a result, the coating 14 in the section 20 is completely removed. In other words, the coating 14 is removed from all sides of the elongated conductor piece 10 in the section 20. In other words, the coating 14 is removed from all sides of the elongated conductor piece 10 in the section 20.

[0070] Because Fig. 1 shows the machine tool 16 during the removal of the coating 14, in Fig. 1 the coating 14 in the area 20 has not yet been completely removed.

[0071] In alternative embodiments not shown, the coating can be removed with a laser beam having a top-hat-shaped intensity distribution in its cross-section and / or a circular, elliptical, square, or rectangular shape. The different shapes are illustrated in Fig. 3. Fig. 3a shows the circular shape, Fig. 3b the elliptical shape, Fig. 3c the square shape, and Fig. 3d the rectangular shape. In particular, it can be seen from Figs. 3c and 3d that the square shape and the rectangular shape have rounded corners. However, this is not mandatory.

[0072] Fig. 4 shows a further embodiment of Fig. 1, wherein the same reference numerals are used for identical and functionally equivalent elements and in this respect reference can be made to the above explanations regarding the embodiment of Fig. 1, so that essentially only the existing differences are discussed.

[0073] In the initial example of Fig. 4, the material of the coating 14 is polyetheretherketone. During a first pass of the laser beam 18 over the section 20, the coating 14 is pre-damaged. This pre-damage includes the formation of carbonization sites 28 in the coating. The carbonization sites 28 form absorption centers in the coating, at which the laser beam is particularly well absorbed during a second pass over the section 20. Therefore, the coating is removed during a second pass of the laser beam 18 over the section 20 by absorption of the laser beam 18 at the carbonization sites 28. In the process, the coating 14 is burned away by the laser beam 18.

[0074] After the coating 14 has been removed, regardless of whether the coating 14 was removed according to the exemplary embodiment in FIG. 1 or 4, the section 20 can be cleaned of contaminants by irradiating the section with the laser beam 18. Contaminants can be, for example, coating residues, smoke and / or dirt. However, cleaning the section 20 is not mandatory. FIG. 5 shows a sectional view of the core 12 in the section 20 after the coating 14 has been removed. FIG. 5 shows that the surface of the core 12, in particular a lateral surface of the core 12, is formed by an oxide layer 30. The oxide layer 30 is an existing oxide layer 30 made of aluminum oxide. The existing oxide layer 30 has scratches 32 and inclusions 34. A thickness 36 of the existing oxide layer 30 is less than 5 pm.The existing oxide layer 30 is therefore unsuitable for preventing unwanted flow and / or running of the melt produced during the welding process from a welding area.

[0075] Fig. 6 shows the elongated conductor piece 10 of Fig. 1 during heating of the electrically conductive core 12 by irradiating the section 20 with the laser beam 18 for the purpose of forming an oxide layer 38 in the section 20. For this purpose, the electrically conductive core 12 is scanned with the laser beam 18.

[0076] The electrically 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 electrically conductive core 12 reacts with oxygen from the environment, forming a homogeneous and / or uniform oxide layer 38.

[0077] A fluence, in particular a total fluence, of the laser beam 18 for heating the electrically conductive core 12 can be, for example, 10 J / cm 2 up to 20 J / cm 2 In the embodiment of Fig. 6, the fluence of the laser beam is 18 15 J / cm 2 .

[0078] In particular, the pulsed laser beam 18 achieves a targeted heat input to the surface of the section 20, which is why damage to the coating 14 present outside the section 20, for example due to a heated electrically conductive core 12, is prevented.

[0079] By irradiating section 20 with laser beam 18, the existing oxide layer 30 is removed and, at the same time, the electrically conductive core 12 is heated. As a result of the heating, an oxide layer 38 is formed on the surface of the electrically conductive core 12. The formation of the oxide layer 38 is a formation of a new oxide layer 38. In other words, the existing oxide layer 30, which has scratches 32 and inclusions 34, is replaced by a new oxide layer 38. Fig. 6 shows a sectional view of the core 12 in section 20 after heating the electrically conductive core 12. The new oxide layer 38 has formed on the surface of the electrically conductive core 12. The new oxide layer 38 is an oxide layer of aluminum oxide. The new oxide layer 38 has no scratches or inclusions. A thickness 40 of the new oxide layer 38 is 20 pm.Thus, the new oxide layer 38 is thicker than the previously removed existing oxide layer 30. The new oxide layer 38 is suitable for preventing unwanted flow and / or running of the melt produced during the welding process from a welding area.

[0080] In an alternative embodiment (not shown), the method comprises the step of flowing an oxidizing agent, particularly a gaseous one in the form of oxygen, over the section. The flow can occur simultaneously with the irradiation of the section with the laser beam.

Claims

Patent claims 1. A method for preparing an elongated conductor piece (10) for a welding process, wherein the elongated conductor piece (10) has an electrically conductive core (12) and a coating (14), wherein the core (12) contains aluminum, the method comprising the steps of: Removing the coating (14) within a section (20) of the elongated conductor piece (10), Heating the electrically conductive core (12) by irradiating the section (20) with a laser beam (18) for the purpose of forming an oxide layer (38) within the section (20).

2. The method according to claim 1, wherein a fluence of the laser beam (18) is 1 J / cm 2 up to 40 J / cm 2 amounts.

3. Method according to one of the preceding claims, wherein the removal of the coating (14) is carried out by irradiating the section (20) with the laser beam (18).

4. Method according to one of the preceding claims, wherein the removal of the coating (14) and the heating of the electrically conductive core (12) are carried out by means of a single pass with the laser beam (18) over the section (20), or wherein the removal of the coating (14) and the heating of the electrically conductive core (12) are carried out by means of a plurality of passes with the laser beam (18) over the section (20).

5. A method according to any one of the preceding claims, wherein the method comprises the step: Cleaning the section (20) of impurities by irradiating the section (20) with the laser beam (18).

6. A method according to any one of the preceding claims, wherein the method comprises the step: Removing an existing oxide layer (30) within the section (20) by irradiating the section (20) with the laser beam (18), wherein the formation of the oxide layer (38) is a formation of a new oxide layer (38).

7. A method according to any one of the preceding claims, wherein the method comprises the step: Flowing over the section (20) with an oxidizing agent, in particular a gaseous one.

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

9. Method according to one of the preceding claims, wherein the laser beam (18) is a pulsed laser beam (18).

10. The method according to claim 9, wherein the irradiation of the section (20) is carried out in such a way that a region (24) irradiated with a laser pulse and a region (26) irradiated with a laser pulse following the laser pulse overlap or do not overlap each other.

11. Machine tool (16), wherein the machine tool (16) is designed to carry out a method according to one of the preceding claims.

Images