Method for the laser welding of components, and assembly of components

Abstract

The invention relates to a method for the laser welding of components (10), comprising the steps: providing at least two components (10), the components (10) being coated and the components consisting of high-strength metal; producing at least three laser spots (12) on at least one surface (14) of at least one component (10), the laser spots (12) each having a core region (16) and a ring region (18), an average laser power density in the core region (16) being higher than an average laser power density in the ring region (18), and the laser spots (12) producing a common molten pool (20) in the components (10). The invention also relates to an assembly of at least two integrally bonded components (10) produced according to a method of this type.

Description

[0001] Title: Process for laser welding of components and

[0002] Arrangement of components

[0003] Description

[0004] The invention relates to a method for laser welding components having the features of claim 1 and to an arrangement of at least two components connected to one another in a materially bonded manner having the features of claim 11.

[0005] High-strength components are used particularly in automotive construction (body construction). These components are typically high-strength steel sheets with an aluminum-silicon coating. Such components can be welded using a laser. In this case, aluminum from the sheet coating can migrate into the weld seam and have an adverse effect on the martensite transformation or martensite formation. Furthermore, aluminum can cause the formation of intermetallic phases, which can serve as a starting point for cracking.

[0006] DE 10 2019 131 906 A1 discloses a method for welding coated steel sheets by means of two laser beams, wherein the laser beams are moved relative to each other.

[0007] It is an object of the present invention to provide a method for laser welding components and an arrangement of components, wherein the above disadvantages are eliminated.

[0008] The above object is achieved by a method for laser welding components having the features of claim 1. The method comprises the steps:

[0009] Providing at least two components. At least one of the components has a coating. This can be an aluminum-silicon coating. The components are made of high-strength steel. The components can be in the form of sheet steel. The high-strength steel can be an MnB (manganese boron) steel, e.g. 22mnB5.

[0010] In the present case, "high-strength" means a metal with a yield strength of at least 550 MPa (megapascals), in particular at least 1000 MPa, preferably at least 1500 MPa, more preferably at least 2000 MPa.

[0011] Generating at least three, in particular four, laser spots on at least one surface of at least one component. The laser spots each have a core region and a ring region. The respective core region can be circular. The respective ring region can be ring-shaped. Other geometric shapes, such as oval, are also conceivable. An average laser power density in the core region of a laser spot is higher than an average laser power density in the ring region (of the same laser spot). The laser spots generate a common melt pool in the components.

[0012] To generate the laser spots, at least one infrared laser with a wavelength in a range from 800 nm (nanometers) to 1200 nm, in particular from 1030 nm or 1070 nm, can be used.

[0013] Alternatively or additionally, at least one laser with a wavelength in the visible range (VIS laser), in particular in a range from 400 nm to 450 nm (blue), in particular from 515 nm (green), can be used.

[0014] To generate the laser spots, a scanner optics with an imaging ratio in a range of 1:1 to 5:1, in particular in a range of 1.5:1 to 2:1, preferably 1.9:1, more preferably 2.5:1, can also be used.

[0015] Alternatively, a fixed lens system can be used to generate the laser spots. This fixed lens system can have an image ratio of 1:1.

[0016] This allows for targeted energy input, optimizing mixing in the molten pool. The formation of critical intermetallic phases can be suppressed. This allows for a high-quality, uniform weld seam with consistent mechanical properties. This allows high-strength and coated components to be welded together reliably and with reproducible, high quality. Tailored welded blanks (workpieces made from individual sheet metal blanks) can be produced, particularly in automotive (body) construction.

[0017] The welding depth using the process can be less than 10 mm (millimeters) and in particular equal to or less than 4 mm.

[0018] It is conceivable that the average laser power density can be adjusted in the core region and / or in the annular region (especially before the welding process). The power component in the core region can range from greater than 0% to less than 100% of the laser power or the power of an output laser beam.

[0019] According to a further development, the procedure may include the following steps:

[0020] Arranging the components in a butt joint and / or arranging the components in a lap joint. With a lap joint, the components are arranged one above the other (in relation to a direction along which the laser spots impinge on the surface). With a butt joint, the components are arranged next to one another, in the same plane (in relation to a direction along which the laser spots impinge on the surface).

[0021] It is also conceivable that the components can be arranged in a parallel butt joint (two or more components arranged parallel and flat), diagonal butt joint (one component arranged at an angle to another component), multiple butt joint (three or more components arranged with their edges abutting against one another), T-joint (one component arranged at right angles to another component (T-shaped)), corner butt joint (two components arranged at an angle to one another) and / or cross butt joint (two components arranged in a cross shape). A combination of the individual butt joint types is also conceivable.

[0022] This allows the components to be arranged very flexibly, so that a variety of different and complex geometries of welded components can be implemented.

[0023] According to a further development, the procedure may include the step :

[0024] Moving the laser spots in a feed direction along a welding path. The laser spots can only be moved in the feed direction along the welding path.

[0025] In this case, the feed direction refers to a local directional value. The feed direction can depend on the course of the weld path. The feed direction can change its orientation or alignment depending on the course of the weld path.

[0026] The laser spots can be kept static with respect to the weld path. In other words, the laser spots are in particular not rotated and / or not moved transversely to the weld path. In particular, the laser spots do not change their relative position with respect to the weld path. The laser spots can be kept static (immobile) relative to one another. At least two laser spots can be arranged one behind the other, at least in some areas, in particular completely, along the feed direction. At least two laser spots can overlap one another, at least in some areas, along the feed direction. There can therefore always be a laser spot moving ahead and a laser spot moving behind, at least in some areas, along the feed direction and / or the weld path. In this way, two laser spots can be moved at least partially over the same area of ​​a component or its surface.

[0027] Two laser spots arranged one behind the other (in the feed direction) can be arranged exactly one behind the other in relation to the feed direction or can be arranged laterally offset from one another.

[0028] For example, with four laser spots, it is conceivable to arrange them in a square arrangement. The four laser spots can each represent a corner of the square of the square arrangement. It is conceivable to orient this square laser spot arrangement such that the edges of the square of the square laser spot arrangement are oriented parallel or perpendicular to the feed direction. Then, two laser spots are arranged exactly one behind the other in the feed direction.

[0029] It is also conceivable to rotate the square arrangement by 90° with respect to the feed direction, so that the edges of the square of the square laser spot arrangement are each inclined by 45° to the feed direction. The laser spots are thus arranged in a (square) rhombus with respect to the feed direction. This means that three laser spots are arranged one behind the other, offset laterally or diagonally in the feed direction. A lateral (diagonal) offset of the laser spots in the feed direction would also be conceivable with a triangular laser spot arrangement with only three laser spots.

[0030] The distance between any two adjacent laser spots (or their centers) can be kept constant. The distance can be 400 pm (micrometers). In this context, adjacent laser spots refer to the nearest laser spots.

[0031] Alternatively, it is conceivable that the distance between two adjacent laser spots (or their centers) can be varied or oscillated.

[0032] This allows the energy input to be distributed specifically to a desired area, the mixing of the melt bath to be adjusted as desired and / or further optimized.

[0033] According to a further development, the procedure may include the step :

[0034] Feeding an additional melting material into the melting bath. The melting material can be a welding wire, in particular a continuous welding wire.

[0035] By adding the additional melt material, a desired alloy composition can be achieved.

[0036] According to a further development, the method may comprise the step of varying, in particular oscillating, the average laser power density of at least one laser spot, its core region, and / or its ring region. It is conceivable that the average laser power density of all laser spots, their respective core regions, and / or their respective ring regions can be varied, in particular oscillated.

[0037] Varying (or oscillating) the average laser power density can be implemented particularly during the welding process. The total laser power can be varied or oscillated during the welding process.

[0038] This allows the degree of mixing in the melt pool to be further increased or adjusted as required.

[0039] According to a further development of the method, the core region of at least one laser spot, in particular of all laser spots, can have a diameter in a range from 50 pm to 400 pm, in particular in a range from 50 pm to 200 pm, preferably 200 pm.

[0040] Alternatively or additionally, the ring region of at least one laser spot, in particular of all laser spots, can have an outer diameter in a range from 40 pm to 2000 pm, in particular in a range from 80 pm to 800 pm, preferably of 700 pm.

[0041] The ring region of at least one laser spot, in particular of all laser spots, has, in particular, an inner diameter that corresponds to the diameter of the respective core region. In other words, the inner diameter of the ring region and the diameter of the respective core region can be the same.

[0042] It is also conceivable for the ring region (or its inner diameter) to be spaced apart from the core region (or its outer diameter). In other words, the inner diameter of the ring region can be larger than the outer diameter of the core region. It is conceivable for a distance, for example, of approximately 10 μm, to be arranged between the ring region and the core region. Thus, an intensity gap can be arranged between the core region and the ring region.

[0043] The ratio between the diameter of the core area and the outer diameter of the respective ring area can be in a range from 1:2 to 1:10, in particular 1:4.

[0044] The core region and the ring region of at least one laser spot, in particular of all laser spots, can each be arranged concentrically. The core region and the ring region of at least one laser spot, in particular of all laser spots, can each be arranged in a circle around a center of the respective laser spot.

[0045] By forming the laser spots in this way, the energy distribution and energy introduction into the melt pool can be further optimized.

[0046] According to a further development of the method, at least two, in particular all, laser spots can be configured identically. It is also conceivable that at least two, in particular all, laser spots can be configured differently.

[0047] This can simplify the generation of the individual laser spots and / or even out the energy distribution.

[0048] According to a further development of the method, the ring regions of at least two, in particular all, laser spots can overlap one another.

[0049] Due to the overlap of the ring areas, the energy input can be further optimized.

[0050] According to a further development of the method, the core regions of at least two, in particular all, laser spots can be arranged at a distance from one another. Core regions of at least two, in particular all, laser spots can be arranged so as not to overlap one another. In other words, the core regions preferably do not overlap.

[0051] Due to the spaced core areas, the energy intensities can be distributed over a larger area and thus the energy input can be further optimized.

[0052] It is conceivable that at least two, in particular all, laser spots can be arranged at a distance from one another. At least two, in particular all, laser spots can be arranged so as not to overlap one another. In other words, the laser spots preferably do not overlap. The core regions and / or the ring regions of at least two, in particular all, laser spots can be arranged at a distance from one another. The ring regions of at least two adjacent laser spots can touch one another (at their respective outer diameters) (have at least one common point).

[0053] It is conceivable that at least two, in particular all, laser spots, whose core regions and / or ring regions can be arranged to overlap one another. For example, the ring regions of at least two (adjacent) laser spots can overlap one another. It is conceivable that a ring region of a laser spot overlaps the core region of an adjacent laser spot.

[0054] When welding two components (e.g., in a butt joint arrangement) using four laser spots, two laser spots can be arranged one behind the other in the feed direction. The four laser spots can be arranged in a square arrangement (i.e., forming a square). Two laser spots can be arranged on each component. The four laser spots can be arranged such that the welding path runs between two pairs of laser spots, each arranged one behind the other in the feed direction.

[0055] This allows the energy input to be distributed as optimally as possible over a corresponding area.

[0056] According to a development of the method, at least one laser spot, in particular all laser spots, can be generated using an optical multi-fiber. The multi-fiber can be a 2-in-1 fiber. The multi-fiber can have a core fiber surrounded by a ring fiber. The multi-fiber can convert an output laser beam into partial beams, wherein the laser spot or the laser spots can be formed from the respective partial beams. The core region and the ring region can be realized with different laser power densities using the individual partial beams.

[0057] The output laser beam can be generated using a disk laser (multi-mode). A beam splitter can be provided to split the output laser beam into two components (core region and ring region).

[0058] At least one laser spot, in particular all laser spots, can be generated by means of a ring fiber fed from several laser modules.

[0059] This makes the production of the laser spot or spots as simple as possible.

[0060] According to a further development of the method, at least two laser spots, in particular all laser spots, can each be generated by means of a separate optical fiber. Additionally or alternatively, at least two, in particular all, laser spots can each be generated by means of a separate laser.

[0061] This allows the individual laser spots to be produced and / or adjusted flexibly and individually. The above object is achieved by an arrangement of at least two components which are materially bonded to one another and have the features of claim 11. The arrangement of components is produced by means of a method according to the above statements. With regard to the advantages which can be achieved thereby, reference is made to the relevant statements on the method. The measures described in connection with the method and / or the measures explained below can be used to further configure the arrangement of components.

[0062] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show:

[0063] Fig. 1 is a schematic representation of a method for laser welding components according to a first embodiment;

[0064] Fig. 2 is a schematic representation of the method for laser welding components according to a second embodiment and

[0065] Fig. 3 is a schematic representation of the method for laser welding components according to a third embodiment.

[0066] In the following description and in the figures, corresponding components and elements bear the same reference numerals. For the sake of clarity, not all reference numerals are shown in all figures. Figure 1 shows a schematic representation of a method for laser welding components 10 according to a first exemplary embodiment. A top view of the components 10 is shown.

[0067] In the present case, two components 10 are arranged in a butt joint. It is also conceivable that more components 10 and / or a different joint arrangement may be present. The components 10 are made of high-strength steel. The components 10 can be steel sheets. In the present case, both components 10 have a coating, in particular an aluminum-silicon coating.

[0068] The components 10 each have a surface 14. In the present case, four laser spots 12 are generated on the surfaces 14 of the two components 10. It is also conceivable that three or more than four laser spots 12 can be generated on the surfaces 14 of the two components 10.

[0069] The laser spots 12 can be generated using an optical multifiber, in particular a 2-in-1 fiber. The laser spots 12 can be generated using an output laser beam (from one laser), which is split into partial beams by the multifiber. It is also conceivable that the laser spots 12 can be generated using multiple output laser beams (from separate lasers).

[0070] The four laser spots 12 are arranged in a square configuration. In other words, the four laser spots 12 are arranged in the shape of a square. Each of the four laser spots 12 forms a corner of the square. Two laser spots 12 are arranged on each component 10 or its respective surface 14.

[0071] Each laser spot 12 has a core region 16 and a ring region 18. In the present case, the core regions 16 are circular. The ring regions 18 are annular. It is conceivable that the core regions 16 and / or the ring regions 18 may each have a different geometric shape (e.g., oval).

[0072] In the present case, the four laser spots 12 are each identically configured. It is also conceivable that the four laser spots 12 could be configured differently. The laser spots 12 generate a common melt pool 20 in the components 10.

[0073] In this case, the laser spots 12 each have a core region 16 with a diameter of 100 pm. The ring regions 18 of the laser spots 12 each have a diameter of 400 pm. The core regions 16 and the ring regions 18 of the respective laser spots 12 are arranged concentrically.

[0074] Within the core areas 16 of the laser spots 12, an average laser power density is greater than an average laser power density within the respective ring areas 18.

[0075] The laser spots 12 can be moved in a feed direction 22 along a welding path 24. In this case, the welding path 24 runs between the two components 10. The feed direction 22 is a local variable. The feed direction 22 depends on the course of the welding path 24. In other words, the feed direction 22 can change its orientation depending on the course of the welding path 24.

[0076] In the present case, the laser spots 12 are moved exclusively in the feed direction 22 along the welding path 24. The laser spots 12 are arranged at a distance from one another. In other words, a distance 26 exists between two adjacent laser spots 12. This distance 26 is kept constant during the movement of the laser spots 12 in the feed direction 22. In other words, the laser spots 12 do not move relative to one another. The distance 26 is greater than 400 pm in the present case. In particular, the individual laser spots 12 do not move in a rotating manner.

[0077] In the present case, two laser spots 12 are arranged one behind the other in the feed direction 22 on each component 10 (square arrangement of the laser spots 12). This results in a leading laser spot 12 and a trailing laser spot 12 on each component 10 or its respective surface 14. As a result, the same area of ​​the respective component 10 or its surface 14 is processed by two laser spots 12 (one after the other). In other words, two laser spots 12 are arranged exactly one behind the other in the feed direction 22. It is also conceivable that the laser spots 12 can be arranged one behind the other in the feed direction 22 at an angle or laterally offset, for example in a diamond-shaped arrangement with respect to the feed direction 22 or with three laser spots 12 and a triangular arrangement.

[0078] The movement of the laser spots 12 in the feed direction 22 and the square arrangement of the laser spots 12 result in a flow direction within the melt bath 20 that is essentially opposite to the feed direction 22. The flow direction of the melt bath 20 is indicated by arrows in Figure 1.

[0079] Figure 2 shows a schematic representation of the method for laser welding components 10 according to a second embodiment.

[0080] The second embodiment of the method differs from the first embodiment shown in Figure 1 in the following:

[0081] An additional melting material is supplied to the melting bath 20. In this case, the additional melting material is in the form of welding wire 28.

[0082] Figure 3 shows a schematic representation of the method for laser welding components 10 according to a third embodiment.

[0083] The third embodiment of the method differs from the first embodiment shown in Figure 1 in the following:

[0084] The four laser spots 12 overlap in the present case with their ring regions 18. The ring regions 18 of each two adjacent laser spots 12 are designed or arranged to overlap one another.

[0085] The core regions 16 of the four laser spots 12 are arranged at a distance from one another. In other words, the core regions 16 of the four laser spots 12 do not overlap.

[0086] The distance between the core areas 16 of two adjacent

[0087] Laser spots 12 are smaller than in the first embodiment shown in Figure 1. The laser spots 12 have been moved closer together (compared to Figure 1).

[0088] In this case, core area 16 and the

[0089] Ring region 18 of two adjacent laser spots 12 does not. However, it is conceivable that the laser spots 12 can be arranged such that the core region 16 and the ring region 18 of at least two adjacent laser spots 12 overlap.

Claims

Patent claims 1. A method for laser welding components (10) comprising the steps: Providing at least two components (10), wherein at least one component (10) is coated, in particular wherein the coated component (10) has an aluminum-silicon coating, wherein the components (10) are formed from high-strength steel; Generating at least three, in particular at least four, laser spots (12) on at least one surface (14) of at least one component (10), wherein the laser spots (12) each have a, in particular circular, core region (16) and a, in particular annular, ring region (18), wherein an average laser power density in the core region (16) is higher than an average laser power density in the ring region (18), wherein the laser spots (12) generate a common melt pool (20) in the components (10).

2. Method according to claim 1, characterized in that the method comprises the steps: Arranging the components (10) in a butt joint and / or Arranging the components (10) in a lap joint.

3. Method according to claim 1 or 2, characterized in that the method comprises the step: Moving the laser spots (12), in particular exclusively, in a feed direction (22), preferably along a welding path (24), wherein along the feed direction (22) at least two Laser spots (12) are arranged at least partially, in particular completely, one behind the other, in particular wherein a distance (26) between each two adjacent laser spots (12) and / or their centers is kept constant.

4. Method according to one of the preceding claims, characterized in that the method comprises the step: Feeding an additional melting material, in particular a welding wire (28), into the melt pool (20).

5. Method according to one of the preceding claims, characterized in that the method comprises the step: Varying, in particular oscillating, the average laser power density of at least one laser spot (12), its core region (16) and / or its ring region (18).

6. Method according to one of the preceding claims, characterized in that the core region (16) of at least one laser spot (12), in particular of all laser spots (12) in each case, has a diameter in a range from 50 pm to 400 pm, in particular in a range from 50 pm to 200 pm, preferably of 200 pm and / or the ring region (18) of at least one laser spot (12), in particular of all laser spots (12) in each case, has an outer diameter in a range from 40 pm to 2000 pm, in particular in a range from 80 pm to 800 pm, preferably of 700 pm, in particular wherein the core region (16) and the Ring region (18) of at least one laser spot (12), in particular all laser spots (12), are each arranged concentrically.

7. Method according to one of the preceding claims, characterized in that at least two, in particular all, laser spots (12) are identical.

8. Method according to one of the preceding claims, characterized in that the ring regions (18) of at least two, in particular all, laser spots (12) overlap one another.

9. Method according to one of the preceding claims, characterized in that the core regions (16) of at least two, in particular all, laser spots (12) are arranged at a distance from one another.

10. Method according to one of the preceding claims, characterized in that at least one laser spot (12), in particular all laser spots (12), are generated by means of an optical multifiber, in particular a 2-in-1 fiber.

11. Method according to one of the preceding claims, characterized in that at least two, in particular all, laser spots (12) are each generated by means of a separate optical fiber and / or by means of a separate laser.

12. Arrangement of at least two components (10) connected to one another in a materially bonded manner, wherein the arrangement is produced by means of a method according to one of the preceding claims.

Images