Medium supply during laser welding

Abstract

The present invention relates to a laser welding apparatus (10) for welding two workpieces (50) along a weld joint, the laser welding apparatus (10) comprising: an optical monitoring device (12) that can be aligned with an observation area (X) around the weld joint to detect the progress of the weld joint; a laser welding head (14) designed to direct a laser processing beam (B) onto at least one of the workpieces (50) based on the detected progress of the weld joint along the weld joint by a welding optical system; and a supply device (20) designed to provide welding adducts and / or process gases, the supply device (20) being positioned on the laser welding head (14) so ​​as to be able to supply the welding adducts and / or process gases to the welding process following the laser processing beam (B) from the supply direction. The present invention further relates to a supply device (20) for use in a laser welding apparatus (10), and a method for welding two workpieces (50).

Description

Technical Field

[0001] The present invention relates to the field of laser welding. Specifically, the present invention relates to the supply of filler materials and / or process gases in a laser welding process, as well as laser welding devices and supply devices for laser welding.

Background Art

[0002] Methods for laser welding in which a metallic workpiece is melted along a weld joint by a laser beam and welded to each other are known from the prior art. In laser welding using a filler material, the supply of the filler material and the supply of a process gas for shielding the molten pool or the solidifying weld seam portion are usually carried out by separate nozzles mounted opposite each other on the welding head. The filler material in the form of a metal wire is preferably introduced into the interaction zone between the laser beam and the workpiece in a trailing manner, i.e., in the feed direction from the front. The process gas, preferably an inert shielding gas such as nitrogen or argon, is directed onto the molten pool, preferably trailing over the solidifying weld seam portion, i.e., from the rear, i.e., using a linear nozzle.

[0003] When the filler material and the process gas are supplied simultaneously, access to the components is considerably restricted due to the opposing arrangement of the respective nozzles, and the welding process zone is difficult or impossible to view for a sensor, specifically to detect the position of the joint (i.e., the weld joint) during the preparation period for the melting zone.

[0004] CN2905302Y describes a combined nozzle for the pre-supply of filler material and process gas. The drawback here is the rigid design of the nozzle. Regardless of the welding operation, for example, even if only the supply of process gas is required to shield the molten pool, and neither filler material nor linear process gas is required to shield the solidifying weld seam, a complete nozzle is required for any medium supply. Therefore, in many welding operations, this combined nozzle unnecessarily negatively impacts the welding process dynamics and contour freedom.

[0005] One objective of the present invention is to improve the accuracy of laser welding, regardless of whether the welding is done manually, thereby improving the quality of the welded joint. At the same time, an objective is to improve the dynamics and / or accessibility during laser welding by supplying the appropriate medium for the welding operation.

[0006] Summary of the Invention The fundamental object of the present invention is achieved by the subject matter of the independent claims. Further possible embodiments of the present invention are specified in the dependent claims, specification, and drawings. Features, advantages, and possible embodiments described in the description of one of the subject matters of the independent claims should be considered in combination with, optionally, one or more of the dependent claims, as well as the features, advantages, and possible embodiments of each subject matter of the other independent claims, and the features, advantages, and possible embodiments of any possible combination of the subject matters of the independent claims.

[0007] According to a first embodiment, a laser welding device is provided for welding two mating partners along a weld joint. The mating partners may preferably be metallic. The laser welding device includes an optical monitoring device that can be aligned with an observation area around the weld joint to detect the path of the weld joint. The phrase "around the weld joint" should be understood in this context to mean that the weld joint extends at least partially through the observation area and is captured within the field of view of the monitoring device. Knowing the precise path of the weld joint allows the welding process to be carried out with particularly high precision.

[0008] The laser welding device further comprises a laser welding head, which is designed by a welding optical system to direct a laser processing beam toward at least one of the mating parts based on the detected path of the weld joint along the weld joint. The laser beam is preferably directed toward both mating parts to be welded together. Due to interaction with the laser beam, the mating parts are locally melted and solidify after the laser beam passes through them, forming a common weld seam. Generally speaking, the path of the welding path can be pre-programmed for the welding operation to be performed. However, in reality, the actual path of the weld joint may deviate from the pre-programmed path. If the actual path of the weld joint deviates from the pre-programmed path, the feed direction can be corrected by detecting the weld joint (using a monitoring device) during an immediate preparation period for the laser beam. In this way, the accuracy of the welding and, consequently, the quality of the welding result can be increased. To detect the actual path of the weld joint, the monitoring device is preferably positioned on the laser welding head and can be transported together with the laser welding head. Furthermore, the monitoring device can be at least partially integrated into the laser welding head, and the monitoring laser beam from the monitoring device is directed coaxially with the processing laser beam into the welding zone. The diameter of the monitoring laser beam is typically larger than that of the processing laser beam. In this way, the weld joint can be detected during the preparation period for the laser beam, even if it is aligned coaxially with the processing laser beam. The monitoring device may also additionally or alternatively include a camera that can be positioned on the welding zone at an angle to or coaxially with respect to the processing laser beam. The monitoring device can be designed, for example, based on an optical coherence tomography (OCT) system. Suitable process monitoring technologies are marketed by the applicant, for example, under the names "SeamLine" or "OCT follow-up control and monitoring".

[0009] The laser welding device also includes a supply device, which is designed to provide filler material and / or process gas (i.e., shielding gas), and is positioned on the laser welding head so as to be able to supply the filler material and / or process gas to the welding process from the supply direction following the laser beam. In other words, the filler material and / or process gas can be supplied to the welding process in advance.

[0010] The filler material is added to the welding process in the interaction zone between the laser beam and at least one of the joining materials. Due to the interaction between the laser beam and the joining material, a molten pool is formed in the interaction zone, which can also be called the processing area. The filler material is added to the molten pool and, together with the joining material during the welding process, forms the resulting weld seam.

[0011] The filler material can be supplied to the welding process by a supply device, preferably in the form of a wire or powder. Powdered filler material is usually supplied to the welding process under pressure along with an inert gas.

[0012] Process gases can be supplied to the welding process in the welding process by a supply device coaxially with the filler material and / or through an elongated region, following the laser beam. When supplying powdered filler material, a separate supply of process gas may be required to shield the molten pool, as the carrier gas of the powder flow substantially reverses the effect of the process gas. The elongated region of the linear process gas supply is configured to shield the molten material solidifying behind the molten pool forming the weld seam from the environment, specifically to prevent oxidation caused by reaction with atmospheric oxygen.

[0013] Preferably, the observation area of ​​the monitoring device is offset in a first direction relative to the laser beam within the surface plane of the workpiece. Furthermore, the feed device can be positioned on the opposite side of the laser welding head from the first direction. Alternatively, the monitoring beam (e.g., monitoring laser beam) can also be positioned concentrically with the processing laser beam, and the observation area can be larger than the projection of the laser beam onto the surface plane of the workpiece. The monitoring beam can be moved back and forth across the workpiece (i.e., across the workpiece) in a pendulum motion traversing the feed direction, for example, preceding the laser processing beam. To specify the precise feeding direction of the processing laser beam, it is important that the monitoring device captures the weld joint during an immediate preparation period for the laser beam. By positioning the feed device to follow the processing laser beam, the monitoring device can be ensured an unobstructed view in the feeding direction of the processing laser beam.

[0014] The supply device and / or monitoring device can also be rotatably mounted on the laser welding head via a common or separate rotating module. In this way, the monitoring laser beam, which is not guided to be concentric with the processing laser beam and / or supply device, can be aligned independently of the orientation of the laser welding head, specifically following the weld contour.

[0015] According to a second embodiment, a supply device is provided for selectively supplying filler material and / or process gas to a welding process. The supply device is suitable for use in a laser welding device according to any one of the modifications described above.

[0016] The supply device comprises a mounting element, which is designed to attach the supply device to the laser welding head of a laser welding device. The mounting element may include a rotary module that can be controlled by a mechanical controller or separately, thereby allowing the mounting element to rotate about the longitudinal axis of the laser welding head. The longitudinal axis of the laser welding head may extend through substantially the center of the focusing optical system of the laser welding head.

[0017] The supply device further comprises an elongated carrier element supported within a mounting element, the carrier element having a medium channel formed therein extending along the carrier longitudinal axis of the carrier element. Preferably, the carrier element can be designed to be hollow cylindrical in shape. The carrier element can be tiltably mounted on the mounting element. For this purpose, the mounting element can specifically have a spherical or hemispherical projection at at least one position on its outer circumference, the projection can be mounted in a recess of the mounting element whose shape is complementary to the projection. Preferably, the longitudinal axis of the carrier element can be positioned at an acute angle with respect to the emission direction of the processing laser beam. To control the tilting of the carrier element, the mounting element can have, for example, a screw (such as a worm screw) and a spring element that secure the carrier element within the mounting element from two sides. The carrier element can be pressed against the spring element by changing the rotational position of the screw. In this way, the alignment angle of the carrier element within the mounting element, i.e., the tilting position, can be changed.

[0018] The supply device further comprises an elongated base element that can be received into a medium channel of a carrier element, and which has a supply channel formed inside for the filler material. The supply channel is designed to guide and supply the filler material to the molten pool during the laser welding process. Preferably, the base element can be designed to be hollow cylindrical in shape. Specifically, the supply channel can be designed to supply filler material in wire form. Alternatively, the supply channel can also be designed to supply filler material in powder form.

[0019] Specifically, the base element can be fitted into the medium channel of the carrier element, forming an annular gap. Specifically, the gap can function as a through-line for process gas for coaxial process gas supply.

[0020] The supply device may also include a first gas supply element having the form of a hollow cylindrical sleeve that can be fitted over the base element and mounted on the outer circumference of the base element and / or carrier element. Mounting is preferably reversible. Depending on the welding operation in which the supply device will be used, the first gas supply element can be selectively attached to the supply device. In welding operations where coaxial process gas supply is not required to cover the molten pool, the first gas supply element can be omitted, which has a positive effect on the weight and dimensions of the supply device, and thus can have a direct positive effect on the dynamics and / or accessibility of the laser welding device. For example, the base element or carrier element may have male threads, and the first gas supply element may have female threads designed to engage with the corresponding male threads. Alternatively, for example, a plug-in fastener can be provided to detachably mount the first gas supply element to the base element and / or carrier element.

[0021] The supply device may further comprise a second gas supply element. The second gas supply element may be mounted on a base element and / or a carrier element. An elongated outlet opening is formed on the underside of the second gas supply element. The term “underside” here refers to the direction of the second gas supply element during operation, such as during a welding process. The second gas supply element further comprises at least two gas channels that open at an acute angle into the outlet opening. The outlet opening may preferably be laterally partitioned by a housing. The housing may be detachably mounted on the body of the second gas supply element. At least two inclined gas channels and other possible connection channels for process gas supply may be milled or drilled into the substrate. The substrate may preferably be made of aluminum or an aluminum alloy. The lateral housing of the outlet opening may preferably be made of copper or another material having good thermal conductivity. In side view, the second gas supply element may have a substantially parallelogram or substantially rhombic shape. This configuration has proven advantageous for supplying a pre-welding medium to the welding process.

[0022] The second gas supply element may have a recess for receiving the first gas supply element. In this case, the first gas supply element can be reversibly attached to the second gas supply element. In this way, the second gas supply element can be attached to the base element and / or carrier element by the first gas supply element. By incorporating the first gas supply element into the second gas supply element, it becomes possible to simultaneously supply gas to the molten pool and to the solidifying weld seam immediately after the molten pool.

[0023] Preferably, a first gas channel can be formed for a first gas supply element, the first gas channel extending from a first gas connection through a gap between a carrier element and a base element, and opening into an annular outlet opening formed by an annular gap between the first gas supply element and the base element. The gap between the carrier element and the base element may include an annular portion and one or more channel-shaped portions. To form an annular outlet opening, the base element has a tapered outer circumference at its outlet end. The first gas supply element has a tapered inner diameter at its outlet end. In the assembled state, the end of the base element protrudes beyond the end of the first gas supply element, and the respective conical regions overlap at least partially in the axial direction. In this way, an annular gap is formed that directs the process gas to concentrate in the molten pool along the outer circumference of the base element during the welding process.

[0024] The second gas supply element may have a separate second gas connection. In other words, the gas connection of the second gas supply element is independent of the gas connection of the first gas supply element. In this way, the coaxial gas supply and the linear gas supply can be controlled independently of each other, which increases flexibility during welding and, where applicable, reduces process gas consumption.

[0025] At least one housing of the second gas supply element surrounding the base element and / or the first gas supply element and / or the elongated outlet opening (below or in the lower region of the second gas supply element) can be made of copper or a copper alloy. Alternatively, the above elements can also be made of another material having particularly good thermal conductivity. During the welding process, the above elements are in particular close proximity to the interaction zone between the laser beam and the workpiece and are therefore exposed to high temperatures. Due to the good thermal conductivity of copper, the heat is dissipated to the nearest component of the supply device, which can be made of aluminum, for example, and preferably can be actively cooled (e.g., by arranging cooling channels in the corresponding areas and connecting them to a cooling system). The modular design of the supply device means that elements that are subjected to particularly high thermal loads can be replaced separately, which increases the overall cost-effectiveness of the supply elements.

[0026] According to a third embodiment, a method is provided for welding two mating parts along a weld joint, the method being carried out by a laser welding device according to one of the modified forms described above. The method includes detecting the path of the weld joint by an optical monitoring device, where the path of the weld joint is captured during a preparation period for the processing laser beam.

[0027] This method further includes melting the mating material along the weld joint with a processing laser beam in a predefined feeding direction. The path of the weld joint detected by a monitoring device can be compared with a weld contour predefined by a welding program. If there is a discrepancy between the detected path and the specified weld contour, the feeding direction of the processing laser beam can be adjusted accordingly.

[0028] This method involves selectively supplying filler material and / or process gas to the welding process from a direction opposite to the feed direction. In other words, the filler material and / or process gas are supplied to the welding process so as to precede it. In this regard, the medium is supplied in any exclusive or combined selection of the following. ● The filler material is supplied to the molten pool generated by the laser beam. ● The process gas is directed (with a directed beam) onto the molten pool to shield the molten pool. ● The process gas is directed to an elongated area following the molten pool to shield the solidifying weld seam portion.

[0029] This selective medium supply enables the welding process to be individually and efficiently adapted to the welding operation.

[0030] Preferably, the monitoring laser beam of the optical monitoring device can be directed at least partially coaxially with the processing laser beam onto the surface of the mating part by the welding optical system. Within the surface plane of the mating part, the diameter of the monitoring laser beam is larger than the diameter of the processing laser beam. In this way, it can be ensured that the weld joint is captured by the monitoring laser beam during the preparation period for the molten pool.

[0031] Alternatively or additionally, the monitoring laser beam can be directed onto the surface plane of the mating part in the feed direction, ahead of the processing laser beam. In this way, the monitoring laser beam can be induced completely independently of the processing laser beam and directed onto the surface of the mating part to detect the weld joint.

[0032] Embodiments for Carrying out the Invention The following description of preferred exemplary embodiments serves to explain the present invention in more detail in conjunction with the drawings.

Brief Description of the Drawings

[0033] [Figure 1]A schematic diagram of the laser welding device according to the present invention is shown. [Figure 2] A block diagram illustrating a method for welding two joining parts using the laser welding device according to the present invention is shown. [Figure 3] Figures 3a and 3b show a supply device according to the present invention in a first modified form. [Figure 4] Figures 4a and 4b show a supply device according to the present invention in a second modified form. [Figure 5] Figures 5a and 5b show a supply device according to the present invention in a third modified form.

[0034] A laser welding device 10 for welding two mating parts 50 along a weld joint according to the present invention will be described in more detail below with reference to Figure 1. The laser welding device 10 includes an optical monitoring device 12 that can be aligned with an observation area X around the weld joint to detect the path of the weld joint. In Figure 1, the weld joint extends along the image plane. The laser welding device further includes a laser welding head 14, which is designed by the welding optics to direct a laser processing beam B towards at least one of the mating parts 50 based on the detected path of the weld joint along the weld joint. Figure 1 shows a side view of the laser welding device 10 along the welding direction or feed direction D so that only one of the mating parts 50 can be seen. It should also be noted that the monitoring device 12 can be used for different types of joints. A classic application area is the welding of two plate-shaped metallic (steel, aluminum, or copper, etc.) mating parts, including butt joints, lap joints, or T-joints. The laser welding device 10 further comprises a supply device 20 designed to provide filler material and / or process gas (not shown), the supply device 20 being positioned on the laser welding head 14 so as to be able to supply the filler material and / or process gas to the welding process from the supply direction in following the laser beam B.

[0035] The filler material can be supplied to the welding process by the supply device 20 in the form of a wire or powder. Furthermore, during the welding process, the process gas can be supplied to the welding process by the supply device 20 coaxially with the filler material and / or through an elongated region, following the laser beam B.

[0036] As shown in Figure 1, the observation area X to which the monitoring laser beam 122 of the monitoring device 12 is directed is offset in a first direction (corresponding to the feeding direction D in Figure 1) relative to the laser beam B within the surface plane of the mating partner 50. Meanwhile, the supply device 20 is positioned to follow the laser welding head 14, that is, to follow the feeding of the laser welding head 14, for the illustrated laser welding process.

[0037] In relation to Figure 2, a method for welding two mating bodies 50 using a laser welding device 10 is described below. In the first step 102, the method includes detecting the path of the welded joint using an optical monitoring device 12. For this purpose, the monitoring laser beam 122 is directed in the feeding direction D, prior to the processing laser beam B, onto the surface plane of the mating bodies 50.

[0038] In the second step 104, the method includes melting the mating body 50 along the weld joint in the feeding direction D with a processing laser beam B. In the third step 106, the method includes selectively supplying filler material and / or process gas to the welding process from a direction opposite to the feeding direction D. Depending on the welding operation, filler material can be supplied to the molten pool 52 generated by the laser beam B, and / or process gas can be directed to the molten pool 52 to shield the molten pool 52, and / or process gas can be directed to an elongated region following the molten pool 52 to shield the solidifying weld seam 54.

[0039] In relation to Figures 3a to 5b, the following describes the supply devices 20 according to the present invention for selectively supplying filler material and / or process gas to the welding process in different modified forms. Each of the supply devices 20 comprises a mounting element 22 designed to mount the supply device 20 to the laser welding head 14 of a laser welding device 10. Furthermore, each supply device 20 comprises an elongated carrier element 24 supported within the mounting element 22, having a medium channel formed therein that extends along the carrier longitudinal axis of the carrier element 24. In addition, each supply device 20 comprises an elongated base element 26 that can be received into the medium channel of the carrier element 24, having a supply channel 262 for the filler material formed therein. The supply of filler material into the supply channel 262 is shown in Figure 1 by the reference numeral "W" and the corresponding arrow.

[0040] The supply device 20 shown in Figures 3a and 3b is configured to supply only the filler material, that is, without supplying additional process gas.

[0041] As shown in the modified forms in Figures 4a and 4b, the supply device 20 may further include a first gas supply element 28, which has the form of a hollow cylindrical sleeve that fits over the base element 26 and can be mounted on the outer circumference of the base element 26 and / or the carrier element 24.

[0042] Alternatively or additionally, the supply device 20 according to the present invention may have a second gas supply element 29. This variant is shown in Figures 5a and 5b. The second gas supply element 29 can be mounted on the base element 26 and / or the carrier element 24. Furthermore, an elongated outlet opening 292 for process gas is formed on the underside of the second gas supply element 29, and the process gas can be directed at an acute angle onto the weld seam 54 through the outlet opening 292 via at least two gas channels 294.

[0043] A first gas channel 25 for the first gas supply element 28 is formed between the base element 26 and the carrier element 24, and the first gas channel 25 extends from the first gas connection G1 through the gap between the carrier element and the base element and opens into an annular outlet opening formed by the annular gap between the first gas supply element 28 and the base element 26. The second gas supply element 29 has a separate second gas connection G2.

[0044] At least one housing 296 of the second gas supply element 29 surrounding the base element 26 and / or the first gas supply element 28 and / or the elongated outlet opening 292 can be made of copper or a copper alloy.

Claims

1. A laser welding device (10) for welding two joining partners (50) along a welded joint, An optical monitoring device (12) that can be aligned with an observation area (X) surrounding the welded joint in order to detect the path of the welded joint, A laser welding head (14) is designed by a welding optical system to direct a laser processing beam (B) onto at least one of the mating parts (50) based on the detected path of the welding joint along the welding joint, A laser welding device (10) comprising: a supply device (20) designed to provide filler material and / or process gas, the supply device (20) being positioned on the laser welding head (14) so ​​as to be able to supply the filler material and / or process gas to the welding process in a supply direction, following the laser processing beam (B).

2. The laser welding device (10) according to claim 1, wherein the filler material can be supplied to the welding process in the form of a wire or powder by the supply device (20).

3. The laser welding device (10) according to claim 1 or 2, wherein the process gas can be supplied to the welding process by the supply device (20) in a manner that follows the laser processing beam (B) and is coaxial with the filler material and / or via an elongated region.

4. The observation area is offset in a first direction with respect to the laser processing beam (B) within the plane of the surface of the bonding partner (50), The laser welding device (10) according to any one of claims 1 to 3, wherein the supply device (20) is located on the side of the laser welding head (14) opposite to the first direction.

5. A supply device (20) for selectively supplying filler material and / or process gas to a welding process, and for use in a laser welding device (10) according to any one of claims 1 to 4, The supply device (20) is designed to be attached to the laser welding head (14) of the laser welding device (10), and includes a mounting element (22), An elongated carrier element (24) supported within the mounting element (22), wherein a medium channel is formed inside the carrier element (24) along the longitudinal axis of the carrier, A supply device (20) comprising: an elongated base element (26) that can be received within the medium channel of the carrier element (24), the elongated base element (26) having a supply channel (262) for the filler material formed inside.

6. The supply device (20) according to claim 5, further comprising a first gas supply element (28) having the form of a hollow cylindrical sleeve that can be fitted over the base element (26) and / or mounted on the outer circumference of the base element (26) and / or the carrier element (24).

7. A second gas supply element (29), It can be attached to the base element (26) and / or the carrier element (24), A long, narrow exit opening (292) is formed on the lower side, and The supply device (20) according to claim 5 or 6, further comprising a second gas supply element (29) having at least two gas channels (294) that open at an acute angle to the outlet opening (292).

8. The supply device (20) according to claim 7, wherein the second gas supply element (29) has a recess for receiving the first gas supply element (28), and the second gas supply element (29) can be attached to the base element (26) and / or the carrier element (24) by the first gas supply element (28).

9. A supply device (20) according to any one of claims 6 to 8, wherein a first gas channel (25) is formed for the first gas supply element (28), the first gas channel (25) extends from a first gas connection portion (G1) through a gap between the carrier element (24) and the base element (26), and opens into an annular outlet opening formed by an annular gap between the first gas supply element (28) and the base element (26).

10. The supply device (20) according to any one of claims 7 to 9, wherein the second gas supply element (29) has a separate second gas connection portion (G2).

11. The supply device (20) according to any one of claims 5 to 10, wherein at least one housing (296) of the base element (26) and / or the first gas supply element (28) and / or the second gas supply element (29) surrounding the elongated outlet opening is made of copper or a copper alloy.

12. A method for welding two mating parts (50) along a weld joint using a laser welding device (10) according to any one of claims 1 to 4, The optical monitoring device (12) detects the path of the welded joint (102), Step (104) of melting the joining mating material along the welded joint in a predetermined feeding direction (D) using the laser processing beam (B), Step (106) of selectively supplying filler material and / or process gas to the welding process from a direction opposite to the aforementioned supply direction (D), The filler material is supplied to the molten pool (52) generated by the laser processing beam (B), and / or The process gas is directed over the molten pool (52) to shield the molten pool (52), and / or A method comprising the step (106) of selectively supplying the process gas so as to be directed onto an elongated region following the molten pool (52) in order to shield the solidifying weld seam (54).

13. The method according to claim 12, wherein the monitoring laser beam of the optical monitoring device (12) is directed by the welding optical system at least partially coaxially with the laser processing beam (B) onto the surface of the workpiece (50), and the diameter of the monitoring laser beam is greater than the diameter of the laser processing beam (B) in the plane of the surface of the workpiece (50).

14. The method according to claim 12, wherein the monitoring laser beam (122) is directed in the feeding direction and prior to the laser processing beam (B) onto the plane of the surface of the bonding partner (50).

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