Medium supply in laser welding

Abstract

The invention relates to a laser welding device (10) for welding two joining partners (50) along a weld joint, comprising: an optical monitoring unit (12) which can be aligned with a viewing region (X) around the weld joint in order to detect the course of the weld joint; a laser welding head (14) which is designed to guide a laser processing beam (B) to at least one of the joining partners (50) along the welding joint by means of a welding optics on the basis of the detected course of the welding joint; and a supply device (20) which is configured to provide a welding additive and / or a process gas and is arranged on the laser welding head (14) such that the welding additive and / or the process gas can be supplied to the welding process from a supply direction following the laser beam (B). The invention further relates to a supply device (20) for use in a laser welding device (10) and to a method for welding two joining partners (50).

Description

Field of the Invention

[0001] The present invention relates to the field of laser welding. In particular, the present invention relates to the supply of welding filler and / or process gas during laser welding, and to laser welding apparatuses and supply apparatuses for laser welding. Background Art

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

[0003] When the welding filler and the process gas are supplied simultaneously, due to the opposed arrangement of the respective nozzles, the accessibility of the components is severely restricted, and it is difficult or impossible for sensors, especially for detecting the position of the joint (or weld joint) relative to the melting zone in the run-up, to view the welding processing zone.

[0004] CN 2905302Y describes a combined nozzle for the guided supply of welding filler and process gas. Here, the disadvantage lies in the rigid design of the nozzle. For any medium supply, the entire nozzle is required regardless of the welding task - even if, for example, only the supply of the process gas is required to protect the molten pool, no welding filler is needed and no linear process gas supply is needed to protect the solidified weld seam. Thus, for many welding tasks, such a combined nozzle has an unnecessary negative impact on the dynamics and contour freedom of the welding process.

[0005] Object of the Invention

[0006] An object of the present invention is to improve the precision of laser welding and thus the quality of the welded connection, regardless of the welding task. At the same time, depending on the welding task, the dynamic performance and / or accessibility during laser welding should be improved using the medium supply. Summary of the Invention

[0007] The object of the invention is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are given in the dependent claims, the description and the drawings. The features, advantages and possible embodiments set out in the description for one of the subject matters of the independent claims are regarded as at least analogous for the corresponding subject matters of the other independent claims and for the features, advantages and possible embodiments of any possible combination of the subject matters of the independent claims (possibly in combination with one or more of the dependent claims).

[0008] According to a first aspect, there is provided a laser welding device for welding two joining partners along a weld joint. The joining partners may preferably be metallic joining partners. The laser welding device comprises an optical monitoring unit which can be aligned with an observation area around the weld joint to detect the course of the weld joint. In this context, the expression "around the weld joint" should be understood to mean that the weld joint at least partially passes through the observation area and is detected by the field of view of the monitoring device. By knowing the exact course of the weld joint, the welding process can be carried out with particularly high precision.

[0009] The laser welding device further comprises a laser welding head which is configured to guide a laser processing beam along the weld joint to at least one of the joining partners by means of welding optics, based on the detected course of the weld joint. The laser beam is preferably aligned with the two joining partners to be welded together. Due to the interaction with the laser beam, the joining partners are locally melted and solidify after the laser beam has passed over them, thereby forming a common weld seam. Generally, the course of the welding path can be pre-programmed for the welding task to be carried out. However, in practice, the actual course of the weld joint may deviate from the pre-programmed course. If the actual course of the weld joint deviates from the pre-programmed course, the feed direction can be corrected by detecting the weld joint relative to the laser beam at the instant of start-up (using the monitoring device). In this way, the welding precision can be increased and thus the quality of the welding result improved. To detect the actual course of the weld joint, the monitoring device may preferably be arranged on the laser welding head and carried along with the laser welding head. The monitoring device may also be at least partially integrated into the laser welding head, wherein the monitoring laser beam from the monitoring device is guided coaxially with the processing laser beam onto the welding zone. The diameter of the monitoring laser beam is generally larger than the diameter of the processing laser beam. In this way, the weld joint can be detected relative to the laser beam at start-up even if the weld joint is aligned coaxially with the processing laser beam. Additionally or alternatively, the monitoring device may further comprise a camera device which can be aligned with the welding zone at an angle or coaxially with the processing laser beam. The monitoring device may be designed, for example, based on an OCT system (OCT, i.e. optical coherence tomography). The applicant has, for example, marketed suitable process monitoring techniques under the names "SeamLine" or "OCT tracking control and monitoring".

[0010] The laser welding device further comprises a supply device which is configured to provide welding filler and / or process gas (or shielding gas), and the supply device is arranged on the laser welding head such that the welding filler and / or process gas can be supplied to the welding process in the supply direction following the laser beam. In other words, the welding filler and / or process gas can be supplied to the welding process in a guiding manner.

[0011] The welding filler is added to the welding process in the interaction zone between the laser beam and at least one joining partner. Due to the interaction between the laser beam and the joining partner, a molten pool is formed in the interaction zone, which can also be referred to as the processing area. The welding filler is added to the molten pool and forms the final weld together with the joining partner during the welding process.

[0012] The welding filler can be supplied to the welding process by the supply device, preferably in the form of a wire or powder. Usually, the powdered welding filler is supplied to the welding process together with an inert gas under a certain pressure.

[0013] The process gas can be supplied to the welding process by the supply device coaxially with the welding filler and / or via an elongated area following the laser beam during the welding process. When supplying powdered welding filler, it may be necessary to supply the process gas separately to shield the molten pool because the carrier gas of the powder flow basically replaces the role of the process gas. The elongated area of the linear process gas supply is constructed in such a way that the solidified melt (which forms the weld) behind the molten pool is isolated from the environment, in particular to prevent oxidation caused by reaction with atmospheric oxygen.

[0014] Preferably, the observation area of the monitoring device is offset in a first direction relative to the laser beam in the surface plane of the joining partner. In addition, the supply device can be arranged on the side of the laser welding head facing away from the first direction. Alternatively, a monitoring beam (e.g., a monitoring laser beam) can also be arranged concentrically with the processing laser beam, wherein the observation area can be larger than the projection of the laser beam on the surface plane of the joining partner. Also, for example, before the laser processing beam, the monitoring beam can be moved back and forth on the workpiece (i.e., the joining partner) in a pendulum movement transverse to the feed direction. Importantly, the monitoring device acquires the weld joint relative to the laser beam at the instant of start-up in order to specify the exact feed direction for the processing laser beam. By arranging the supply device in a manner following the processing laser beam, an unobstructed view in the feed direction of the processing laser beam relative to the monitoring device can be ensured.

[0015] The supply device and / or the monitoring device can also be rotatably arranged on the laser welding head via a common or separate rotation module. In this way, a monitoring laser beam that is not guided concentrically with the processing laser beam and / or the supply device can be aligned following the welding profile regardless of the orientation of the laser welding head.

[0016] According to a second aspect, there is provided a supply device for selectively supplying welding filler and / or process gas to a welding process. The supply device is suitable for a laser welding device according to any of the above-described variants.

[0017] The supply device includes a fixing element configured to fix the supply device to the laser welding head of the laser welding device. The fixing element may include a rotation module that may be controlled by a machine controller or controlled separately, and by using this rotation module, the fixing element can be rotated about the longitudinal axis of the laser welding head. The longitudinal axis of the laser welding head may pass substantially centrally through the focusing optics of the laser welding head.

[0018] The supply device further includes an elongate carrier element supported in the fixing element and having a medium channel extending along the carrier longitudinal axis of the carrier element formed therein. Preferably, the carrier element may be configured in the shape of a hollow cylinder. The carrier element may be mounted obliquely on the fixing element. For this purpose, the fixing element may particularly have a spherical or hemispherical projection at at least one position on its outer periphery, and the spherical or hemispherical projection may be mounted in a groove in the fixing element that is complementary in shape to the projection. Preferably, the longitudinal axis of the carrier element may be arranged at an acute angle to the exit direction of the processing laser beam. To control the inclination of the carrier element, the fixing element may, for example, have screws (such as worm screws) and spring elements that fix the carrier element in the fixing element from both sides. The carrier element can be pressed against the spring element by changing the rotational position of the screws. In this way, the alignment angle or inclination position of the carrier element in the fixing element can be changed.

[0019] The supply device further includes an elongate base element that can be received in the medium channel of the carrier element and having a supply channel for the welding filler formed therein. The supply channel is configured to guide the welding filler during the laser welding process and supply the welding filler to the molten pool. Preferably, the base element may be configured in the shape of a hollow cylinder. In particular, the supply channel may be configured for supplying wire-shaped welding filler. Alternatively, the supply channel may also be configured for supplying welding filler in powder form.

[0020] In particular, the base element may be mounted in the medium channel of the carrier element to form an annular gap. In particular, this gap may be used as a process gas through-line for coaxial process gas supply.

[0021] The supply device may also include a first gas supply element having the form of a hollow cylindrical sleeve that can be slipped over the base element and mounted on the outer periphery of the base element and / or the carrier element. This mounting is preferably reversible. Depending on the welding task for which the supply device is to be used, the first supply element can be selectively attached to the supply device. For welding tasks that do not require coaxial process gas supply to cover the molten pool, the first gas supply element can be omitted, which can have a positive impact on the weight and size of the supply device and thus a direct positive impact on the dynamics and / or accessibility of the laser welding device. For example, the base element or the carrier element may have an external thread, and the first gas supply element may have an internal thread configured to engage the corresponding external thread. Alternatively, for example, plug-in fasteners can be provided for detachably fixing the first gas supply element to the base element and / or the carrier element.

[0022] The supply device may also include a second gas supply element. The second gas supply element can be mounted on the base element and / or the carrier element. A long-shaped outlet opening is configured on the lower side of the second gas supply element. Here, the term "lower side" refers to the direction indication during the operation of the second gas supply element, such as during the welding process. The second gas supply element also has at least two gas channels that open into the outlet opening at an acute angle. The outlet opening can preferably be laterally defined by a housing. The housing can be detachably mounted on the base body of the second gas supply element. The above-mentioned at least two inclined gas channels and other possible connection channels for process gas supply can be particularly milled or drilled into the base body. The base body can preferably be made of aluminum or an aluminum alloy. The lateral housing of the outlet opening can preferably be made of copper or other materials with good heat conduction properties. In a side view, the second gas supply element can have an approximate shape of a parallelogram or a rhombus. This form has proven to be advantageous for guiding the supply of the medium to the welding process.

[0023] The second gas supply element may have a groove for receiving the first gas supply element. In this case, the first gas supply element can be reversibly mounted on the second gas supply element. In this way, the second gas supply element can be mounted on the base element and / or the carrier element by means of the first gas supply element. Integrating the first gas supply element into the second gas supply element also enables the simultaneous supply of gas to the molten pool and to the solidified weld seam immediately following the molten pool.

[0024] Preferably, a first gas channel can be formed for the first gas supply element, which extends from the first gas connection via the gap between the carrier element and the base element, and the first gas channel opens into an annular outlet opening formed by the annular gap between the first gas supply element and the base element. The gap between the carrier element and the base element can include an annular portion and one or more channel-like portions. To form the annular outlet opening, the base element has a conical outer circumference outside its outlet end. The first gas supply element has a conical outer circumference at its outlet end. In the assembled state, the end of the base element projects beyond the end of the first gas supply element, wherein the respective conical regions at least partially overlap in the axial direction. In this way, an annular gap is formed, which guides the process gas along the outer circumference of the base element in a focused manner onto the weld pool during the welding process.

[0025] The second gas supply element can 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 the flexibility during welding and reduces the process gas consumption in applicable cases.

[0026] At least one housing of the base element and / or the first gas supply element and / or the second gas supply element surrounding the elongated outlet opening (in the lower side or lower region of the second gas supply element) can be made of copper or a copper alloy. Alternatively, the elements in question can also be made of other materials with particularly good heat-conducting properties. During the welding process, the elements in question are particularly close to the interaction zone between the laser beam and the workpiece and are thus exposed to high temperatures. Due to the good heat-conducting properties of copper, the heat is dissipated into the nearest components of the supply device, which can, for example, be made of aluminum, and the nearest components can preferably be actively cooled (e.g., by arranging cooling channels in the corresponding areas and connecting the cooling channels to a cooling system). The modular design of the supply device means that the components subjected to particularly high heat loads can be replaced individually, which improves the overall cost-effectiveness of the supply elements.

[0027] According to a third aspect, a method for welding two joining partners along a weld joint is provided, which can be implemented by a laser welding device according to one of the above-described variants. The method includes detecting the course of the weld joint by means of an optical monitoring unit. Here, the course of the weld joint is acquired relative to the processing laser beam at startup.

[0028] The method further includes melting the joining partners along the weld joint in a predeterminable feed direction by means of a processing laser beam. The course of the weld joint detected by the monitoring device can be compared with a weld profile specified in advance by the welding program. In the case of a deviation between the detected course and the specified weld profile, the feed direction of the processing laser beam can be adjusted accordingly.

[0029] The method includes selectively supplying a welding filler and / or a process gas to the welding process from a direction opposite to the feed direction. In other words, the welding filler and / or the process gas are supplied to the welding process in a directed manner. In this regard, the supply medium is selected in any exclusive or combined manner from the following:

[0030] · Supplying the welding filler to the molten pool generated by the laser beam;

[0031] · Guiding the process gas (in a directed beam) onto the molten pool to shield the molten pool;

[0032] · Guiding the process gas onto an elongate region following the molten pool to shield the solidified weld seam.

[0033] This selective medium supply enables the welding process to be applied to the welding task individually and efficiently.

[0034] Preferably, the monitoring laser beam of the optical monitoring unit can be guided at least partially coaxially with the processing laser beam onto the surface of the joining partners by means of welding optics, wherein, in the surface plane of the joining partners, the diameter of the monitoring laser beam is greater than the diameter of the processing laser beam. In this way, it can be ensured that the monitoring laser beam captures the weld joint relative to the molten pool at the start.

[0035] Alternatively or additionally, the monitoring laser beam can be guided onto the surface plane of the joining partners in the feed direction in front of the processing laser beam. In this way, the monitoring laser beam can be guided completely independently of the processing laser beam and onto the surface of the joining partners to detect the weld joint. Description of the Drawings

[0036] The following description of the preferred embodiments serves to explain the present invention in more detail in conjunction with the drawings.

[0037] In the drawings:

[0038] Figure 1 A laser welding device according to the present invention is schematically shown.

[0039] Figure 2 A block diagram showing a method of welding two joining partners by means of a laser welding device according to the present invention is shown;

[0040] Figures 3a to 3bshows a supply device according to the invention according to a first variant;

[0041] Figures 4a to 4b shows a supply device according to the invention according to a second variant; and

[0042] Figures 5a to 5b shows a supply device according to the invention according to a third variant. Detailed Description

[0043] The following refers to Figure 1 a laser welding device 10 for welding two joining partners 50 along a weld joint according to the invention will be described in more detail. The laser welding device 10 includes an optical monitoring unit 12, which can be aligned with an observation area X around the weld joint to detect the orientation 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 configured to direct a laser processing beam B to at least one of the joining partners 50 along the weld joint based on the detected orientation of the weld joint by means of welding optics. Since Figure 1 a side view of the laser welding device 10 along the welding direction or feed direction D is shown, only one of the joining partners 50 can be seen. It should also be noted that the monitoring device 12 can be used for different types of joints. Typical application areas are welding two plate-shaped metal (such as steel, aluminum or copper) joining partners using butt joints, lap joints or T-joints. The laser welding device 10 further includes a supply device 20, which is configured to provide a welding filler and / or a process gas (not shown in the figure), and the supply device is arranged on the laser welding head 14 such that the welding filler and / or the process gas can be supplied to the welding process from the supply direction following the laser beam B.

[0044] The welding filler can be supplied to the welding process by the supply device 20 in the form of a wire or in the form of a powder. In addition, during the welding process, the process gas can be supplied to the welding process coaxially with the welding filler and / or via an elongated area following the laser beam B by means of the supply device 20.

[0045] According to Figure 1 the illustration in, the observation area X (the monitoring laser beam 122 of the monitoring device 12 is aligned with this observation area) is offset in the surface plane of the joining partner 50 in a first direction (corresponding to the feed direction D in Figure 1 ) with respect to the laser beam B. In contrast, for the shown laser welding process, the supply device 20 is arranged in a trailing manner on the laser welding head 14, that is, following the feed of the laser welding head 14.

[0046] In combination with Figure 2, a method for welding two joining partners 50 by means of a laser welding device 10 is described below. In a first step 102, the method includes detecting the course of the weld joint by means of an optical monitoring unit 12. For this purpose, a monitoring laser beam 122 is guided onto the surface plane of the joining partner 50 in front of the processing laser beam B in the feed direction D.

[0047] In a second step 104, the method includes melting the joining partner 50 along the weld joint in the feed direction D by means of the processing laser beam B. In a third step 106, the method includes selectively supplying welding filler and / or process gas to the welding process from a direction opposite to the feed direction D. Depending on the welding task, welding filler can be supplied to the molten pool 52 generated by the laser beam B, and / or process gas can be guided to the molten pool 52 to shield the molten pool 52, and / or process gas can be guided to an elongated region following the molten pool 52 to shield the solidified weld seam 54.

[0048] Combined Figures 3a to 5b , different variants of a supply device 20 for selectively supplying welding filler and / or process gas to a welding process according to the present invention are described below. Each supply device 20 includes a fixing element 22 configured to fix the supply device 20 to a laser welding head 14 of a laser welding device 10. In addition, each supply device 20 includes an elongated carrier element 24 supported in the fixing element 22 and having a medium channel extending along a carrier longitudinal axis of the carrier element 24 formed therein. In addition, each supply device 20 includes an elongated base element 26 that can be received in the medium channel of the carrier element 24 and having a supply channel 262 for welding filler formed therein. Figure 1 The supply of welding filler into the supply channel 262 is indicated by the reference sign "W" and the corresponding arrow in

[0049] According to Figure 3a and Figure 3b , the supply device 20 is configured in the form shown for the sole supply of welding filler, i.e., without additional supply of process gas.

[0050] As shown in the variant according to Figure 4a and Figure 4b , the supply device 20 can additionally have a first gas supply element 28 having the form of a hollow cylindrical sleeve that can be slipped over the base element 26 and mounted on the outer periphery of the base element 26 and / or the carrier element 24.

[0051] Alternatively or additionally, the supply device 20 according to the present invention can have a second gas supply element 29. This variant is shown in Figure 5a andFigure 5b is shown. 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 configured on the lower side of the second gas supply element 29, and the process gas can be aligned via the outlet opening 292 at an acute angle to the weld seam 54 via at least two gas channels 294.

[0052] A first gas channel 25 for the first gas supply element 28 is configured between the base element 26 and the carrier element 24, and this first gas channel extends from the first gas connection G1 via the gap between the carrier element and the base element, and this first gas channel leads to 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.

[0053] 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 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 weld joint, the laser welding device (10) comprises: an optical monitoring unit (12) which can be aligned with an observation area (X) around the weld joint to detect the orientation of the weld joint; a laser welding head (14) which is configured to direct a laser processing beam (B) along the weld joint to at least one of the joining partners (50) by means of welding optics based on the detected orientation of the weld joint; and a supply device (20) which is configured to provide welding filler and / or process gas, and the supply device is arranged on the laser welding head (14) such that the welding filler and / or the process gas can be supplied to the welding process from a supply direction following the laser beam (B).

2. The laser welding device (10) according to claim 1, wherein the welding filler can be supplied to the welding process in the form of a wire or in the form of a powder by means of 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 means of the supply device (20) coaxially with the welding filler and / or via an elongated area following the laser beam (B) during the welding process.

4. The laser welding device (10) according to any one of the preceding claims, wherein the observation area is offset in a first direction relative to the laser beam (B) in the surface plane of the joining partners (50); and wherein the supply device (20) is arranged on a side of the laser welding head (14) facing away from the first direction.

5. A supply device (20) for selectively supplying welding filler 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) comprises: a fixing element (22) which is configured to fix the supply device (20) to the laser welding head (14) of the laser welding device (10); an elongated carrier element (24) which is supported in the fixing element (22), and a medium channel extending along the carrier longitudinal axis of the carrier element is constructed inside the carrier element; and an elongated base element (26) which can be received in the medium channel of the carrier element, and a supply channel (262) for the welding filler is constructed inside the base element.

6. The supply device (20) according to claim 5, further comprises: a first gas supply element (28) which has the form of a hollow cylindrical sleeve that can be put on the base element (26) and fixed on the outer periphery of the base element (26) and / or the carrier element (24).

7. The supply device (20) according to claim 5 or 6 further comprises a second gas supply element (29), wherein the second gas supply element can be fixed to the base element (26) and / or the carrier element (24), a long outlet opening (292) is formed on the lower side of the second gas supply element, and the second gas supply element has at least two gas channels (294) that open into the outlet opening (292) at an acute angle.

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

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

12. A method for welding two joining partners (50) along a weld joint by means of the laser welding device (10) according to any one of claims 1 to 4, the method comprises the following steps: detecting (102) the orientation of the weld joint by means of the optical monitoring unit (12); melting (104) the joining partners along the weld joint in a predeterminable feed direction (D) by means of a processing laser beam (B); selectively supplying (106) welding filler and / or process gas to the welding process from a direction opposite to the feed direction (D); wherein the welding filler is supplied to the molten pool (52) generated by the laser processing beam (B); and / or wherein the process gas is directed at the molten pool (52) to shield the molten pool (52); and / or wherein the process gas is directed at a long region following the molten pool (52) to shield the solidified weld seam (54).

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

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

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