Device and method for laser welding of components

Abstract

The invention relates to a device for laser welding of components (2, 3) with at least one laser beam emitter and at least one pressure piece (1), which - is designed to be pressed against at least one of the components (2, 3), and - has a laser channel (5) through which a laser beam (LS) emitted by means of the laser beam emitter can be guided onto a surface of at least one of the components (2, 3). According to the invention, in a wall (4) surrounding the laser channel (5) and forming its outer surface, at least one shielding gas channel (6.1 to 6.4) is formed in an inner section facing the laser channel (5), which can be supplied with a shielding gas (SG) and has at least one shielding gas outlet (SGA) that leads through the wall (4) into the laser channel (5). Furthermore, in the wall (4), at least one cooling channel (7) is formed in an outer section facing away from the laser channel (5), which can be supplied with a cooling medium (KM). The invention further relates to a method for laser welding of components (2, 3).

Description

[0001] The invention relates to a device for laser welding of components.

[0002] The invention further relates to a method for laser welding of components.

[0003] From DE 10 2016 221 364 B3, a laser processing device for processing workpieces using laser radiation is known. The laser processing device comprises a pressure piece configured to be pressed against a workpiece to be processed in order to fix the workpiece during laser processing. A heating device for heating the workpiece is integrated into the pressure piece. The pressure piece is designed as a laser-guiding pressure piece and has a channel through which laser radiation can be directed onto the workpiece during laser processing. The heating device completely surrounds the channel and comprises an induction coil configured to induce a magnetic field in the workpiece when subjected to an alternating voltage with a frequency of 1 kHz to 1 MHz, thereby generating eddy currents in the workpiece and heating it.

[0004] The JP - S62 6 912 B2 describes a laser spot welding device that welds polymerized workpieces by spot welding using a laser beam from a laser generator.

[0005] DE 198 58 018 C1 describes a device and a method for welding sheet steel using a laser.

[0006] The present invention is based on the objective of providing a novel device and a novel method for laser welding of components.

[0007] The problem is solved according to the invention by a device which has the features specified in claim 1 and by a method which has the features specified in claim 9.

[0008] Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] The device according to the invention for laser welding of components comprises at least one laser beam emitter and at least one pressure piece. The pressure piece is designed to be pressed against at least one of the components and has a laser channel through which a laser beam emitted by means of the laser beam emitter can be guided onto a surface of at least one of the components.

[0010] In a wall surrounding the laser channel and forming its outer surface, at least one shielding gas channel is formed in an inner section facing the laser channel. This channel can be supplied with a shielding gas and has at least one shielding gas outlet that leads through the wall into the laser channel. Furthermore, at least one cooling channel is formed in the wall in an outer section facing away from the laser channel. This cooling channel can be supplied with a cooling medium.

[0011] Using at least one pressure piece, the components to be welded are mechanically pressed together during laser beam welding to create a virtually zero gap. This means that no gap should occur between the components being joined. Additional pressure pieces or counter bearings can be provided, which rest directly against the components to be joined and, together with the counterpart, forcefully press the components together. Particularly during closely spaced welding processes of numerous component joints, a large amount of heat is transferred into the pressure piece.

[0012] By means of the at least one cooling channel provided in the pressure piece according to the present device, which is coupled to or part of a cooling circuit, temperatures in both the wall of the pressure piece and in the components, especially temperature-sensitive components, can be maintained at a level that is harmless to the temperature-sensitive component during several welding processes. This allows all welds to be carried out reliably and stably over several process steps under reproducible environmental conditions without affecting the temperature-sensitive components and with a short cycle time. Therefore, the device is particularly suitable for joining a large number of components, for example, for contacting battery cells with a cell connector unit.This reliably prevents thermal damage to components and negative impacts on the laser welding process resulting from overheated pressure pieces. Furthermore, due to its active cooling, the pressure piece can be used to create component joints where at least one component is made of temperature-sensitive materials or contains such materials in certain sections. Because of its low temperature, the pressure piece can be placed in direct contact with the component to reliably clamp it and simultaneously cool it during the welding process.

[0013] Due to the at least one shielding gas channel formed in the wall of the pressure piece and the supply of the shielding gas into the laser channel, the emitted laser beam is completely surrounded by the pressure piece at least at a sufficient distance from the component surface, so that a sufficient shielding gas atmosphere can be created and an environment around the welding area is shielded from escaping weld metal.

[0014] The wall is designed as a double shell, with an inner shell forming the inner section of the wall and coaxially surrounding the laser channel, and an outer shell forming the outer section of the wall and coaxially surrounding both the laser channel and the inner shell. This simplifies the manufacturing of the pressure piece, as the at least one cooling channel can be formed separately in the outer shell and the at least one protective gas channel separately in the inner shell. The two shells can then be easily assembled to form the single wall. For example, the two shells can be machined as turned and / or milled parts and pressed together to create the pressure piece. With such a multi-shell design, the shells can be made of different materials and thus optimally adapted to their respective functions.For example, the shell facing the laser channel can be made of a metal, such as aluminum, copper, steel, or a combination thereof, or of a ceramic. The shell facing away from the laser channel, which is intended to guide the cooling medium, can be made of plastic, for example. Alternatively, the printed part can also be manufactured using other conventional methods, such as additive manufacturing.

[0015] In one possible embodiment of the device, the pressure piece is made of a metallic material, for example, aluminum, copper, steel, or a combination thereof. The pressure piece can also be made of a ceramic material and / or plastic. In particular, the material for the pressure piece can be flexibly adapted depending on the welding application.

[0016] In another possible embodiment of the device, the at least one cooling channel meanders within the wall or is positioned in such a way that it spirals around the laser channel or surrounds it coaxially. This design of the at least one cooling channel allows for a particularly large cooling surface area, resulting in effective and powerful cooling. Furthermore, this design enables simple and efficient dissipation of heat energy to a heat sink. In particular, the number, arrangement, and design of the cooling channels can be flexibly selected depending on the thermal requirements of the pressure piece.

[0017] In another possible embodiment of the device, at least one shielding gas channel surrounds the laser channel coaxially. This allows for a larger shielding gas outlet in the circumferential direction of the laser channel, ensuring a particularly uniform supply of the gas to the laser channel. It is also possible to provide multiple shielding gas channels. In particular, the number, arrangement, and design of shielding gas channels can be flexibly selected depending on the requirements for the shielding gas supply to the pressure piece.

[0018] In another possible embodiment of the device, an outer and / or inner circumference of the wall extends from a first outer surface of the pressure piece to a second outer surface opposite it, which is designed to contact the at least one component. Due to the smaller free cross-section of the laser channel on the component-facing side, this allows for optimized delimitation of the welding area from its movement and, simultaneously, optimal control of the laser beam's emission direction with respect to its angle to the component surface and its point of impact. However, the geometry of the pressure piece can deviate from this embodiment in other possible embodiments and is particularly flexible – for example, depending on the design of a weld contour and joining point.

[0019] In another possible embodiment of the device, the outer and / or inner shape of the wall is frustoconical. Such a frustoconical design is particularly suitable for oscillating laser beams while simultaneously optimizing the delimitation of the welding area.

[0020] In another possible embodiment of the device, the outer and / or inner shape of the wall is frustoconical or frustoelliptic conical. Such a frustoconical or frustoelliptic conical design is particularly suitable for oscillating laser beams while simultaneously optimizing the delimitation of the welding area.

[0021] In another possible embodiment of the device, at least one shielding gas outlet channel is formed in an end region of the wall facing a second outer surface, which is provided for contact with the at least one component. This channel extends completely through the wall from the laser channel to an outer surface of the wall, allowing excess shielding gas to escape from the laser channel.

[0022] In another possible embodiment of the device, the pressure piece is mechanically fixed to a welding optics unit. This ensures that the pressure piece is always optimally positioned relative to the welding optics unit and can be positioned together with it relative to the components. This also facilitates, for example, automated positioning of the pressure piece together with the welding optics unit, such as by a robot. Alternatively, the pressure piece can also be moved, traversed, and positioned independently of the welding optics unit.

[0023] In the inventive method for laser welding components using a aforementioned device, it is provided that - the components to be welded are positioned relative to each other in a welding position, - the pressure piece is pressed against at least one of the components, - the at least one shielding gas channel, which is formed in the double-shell wall in the outer section facing the laser channel and formed by means of the inner shell coaxially surrounding the laser channel, is supplied with a shielding gas in such a way that this gas escapes into the laser channel through the shielding gas outlet, - at least one cooling channel, which is formed in the double-shell wall in the outer section facing away from the laser channel and formed by means of the outer shell coaxially surrounding the laser channel and the inner shell, is supplied with a cooling medium, - a laser beam is emitted by means of the laser beam emitter and directed onto a surface of at least one of the components and - by means of the laser beam at least one of the components is melted in such a way that, after a molten area has solidified, a weld connection is created between the components.

[0024] Using the present method, it is possible to maintain temperatures in both the wall of the pressure piece and in the components, especially temperature-sensitive components, at a level that is harmless to the temperature-sensitive component throughout several welding processes. This allows all welding operations to be carried out reliably over several process steps under reproducible environmental conditions without affecting the temperature-sensitive components. In other words, thermal damage to the components and negative impacts on the laser welding process resulting from overheated pressure pieces can be reliably avoided. The method is also suitable for creating component joints where at least one of the components is made of temperature-sensitive materials or contains such materials, at least in certain sections.Due to its low temperature, the pressure piece can be placed in direct contact with the corresponding component to clamp the components reliably during the process.

[0025] Furthermore, the process enables the supply of the shielding gas into the laser channel through the wall of the pressure piece, so that a sufficient shielding gas atmosphere can be created, the emitted laser beam is completely surrounded by the pressure piece at least at a sufficient distance from the component surface, and at the same time an environment around the welding area is shielded from escaping weld metal.

[0026] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0027] This shows: Fig. 1. Schematic, a perspective, semi-transparent view of a printed piece of a device for laser welding components and Fig. 2. Schematic cross-sectional view of the printed piece according to Fig. 1 during laser welding of components.

[0028] Corresponding parts are marked with the same reference symbols in all figures.

[0029] In Fig. Figure 1 is a perspective semi-transparent view of a printed piece 1 of a device for laser welding of in Fig. 2 components shown in more detail 2, 3. Fig. Figure 2 shows a sectional view of the printed piece 1 according to Fig. 1 during laser welding of components 2, 3.

[0030] Components 2 and 3 are intended, for example, for the electrical contacting of electrical storage units. For example, components 2 and 3 are cell connectors and cell poles of electrochemical single cells, wherein component 2 comprises, for example, an electrically conductive metallic section 2.1, such as a cell connector section, and an electrically insulating section 2.2, such as an injection-molded coating formed from a temperature-sensitive plastic component.

[0031] The pressure piece 1 is designed to be pressed onto the surface of at least one of the components 2, 3 with a force F in order to securely press the components 2, 3 together to create a welded joint SV between them. In particular, such pressing ensures, on the one hand, a zero gap between the components 2, 3 and, on the other hand, securely fixes the components 2, 3 in their relative position to each other.

[0032] The pressure piece 1 is designed as a hollow truncated circular cone with a laser channel 5 surrounded by a wall 4. A laser beam LS, emitted by a laser emitter (not shown) and controlled in its optical properties, position, and orientation by a welding optics unit (also not shown), is guided through this laser channel 5 onto a surface of at least one of the components 2, 3. The wall 4 enables the transmission of the force F to the components 2, 3, the shielding of the area around a weld from escaping weld metal, and the generation of a protective gas atmosphere in the laser channel 5, at least in the region of the laser beam LS's point of impact. In the illustrated embodiment, the wall 4 is designed as a double shell, with an inner shell 4.1 forming an inner section of the wall 4 and coaxially surrounding the laser channel 5, and an outer shell 4.2 forms an outer section of the wall 4 and coaxially surrounds the laser channel 5 and the inner shell 4.1. The two shells 4.1, 4.2 are connected to each other by force, material and / or form fit, for example by pressing and / or bonding and / or welding.

[0033] To generate the protective gas atmosphere, a supply of protective gas SG into the laser channel 5, particularly in the area of ​​the laser beam's impact position LS, is required. For this purpose, protective gas channels 6.1 to 6.4 are formed in the inner shell 4.1, each of which has a protective gas outlet SGA leading through the wall 4 into the laser channel 5. The protective gas channels 6.1 to 6.4 each extend from an upper outer surface of the pressure piece 1, facing away from components 2 and 3, towards a second outer surface of the pressure piece 1 opposite this surface and intended to contact at least one of components 2 and 3, and each terminates in its corresponding protective gas outlet SGA. In embodiments of the pressure piece 1 not shown in detail, any other number and arrangement of protective gas channels 6.1 to 6.4 may be provided. It is also possible that the inner shell 4.1 is designed at least substantially as a hollow body such that a protective gas channel 6.1 coaxially surrounding the laser channel 5 is formed within it.

[0034] To remove excess shielding gas SG during the laser welding process, several shielding gas outlet channels SGK are formed in an end area of ​​the wall 4 facing a second outer surface which is intended to be attached to at least one component 2, 3, extending completely through the wall 4 from the laser channel 5 to an outer surface of the wall 4.

[0035] During the laser welding process, heat is introduced into the pressure piece 1. Particularly during consecutive welding operations of numerous component joints, a large amount of heat is introduced into the pressure piece 1. To avoid long cooling phases of the pressure piece 1, and thus long cycle times, as well as to prevent impairment of the laser welding process and damage to components 2 and 3 caused by high temperatures, the pressure piece 1 is designed for active cooling.

[0036] For this purpose, a cooling channel 7 is formed in the outer section of the wall 4, facing away from the laser channel 5, i.e., in the outer shell 4.2. This cooling channel can be supplied with a cooling medium KM, for example, a coolant. In the illustrated embodiment, the cooling channel 7 extends at least substantially in a meandering pattern from the first outer surface of the pressure piece 1 towards the second outer surface of the pressure piece 1. In embodiments of the pressure piece 1 not shown in detail, any other number and arrangement of cooling channels 7 can be provided. For example, a cooling channel 7 can spiral around the laser channel 5. It is also possible for the outer shell 4.2 to be designed at least substantially as a hollow body such that a cooling channel 7 coaxially surrounding the laser channel 5 is formed within it.

[0037] In exemplary embodiments not shown in detail, the pressure piece 1 can also have any other suitable geometry in which the laser channel 5 is surrounded by a wall 4 with at least one integrated protective gas channel 6.1 to 6.4 and at least one integrated cooling channel 7, in a geometry deviating from the geometry designed as a hollow truncated circular cone.

[0038] To carry out the laser welding process according to the illustrated embodiment, the components 2, 3 to be welded are first positioned relative to each other in a welding position. The pressure piece 1 is then pressed against component 2 by placing it on a surface of the section 2.2 of component 2, which is designed to be particularly temperature-sensitive. Due to the active cooling of the pressure piece 1, it can be kept at a temperature at which temperature-related damage to section 2.2 can be avoided.

[0039] The cooling channel 7 is then supplied with the cooling medium KM. For example, a cooling liquid is pumped through the cooling channel 7. Simultaneously, before or after this, the shielding gas channels 6.1 to 6.4 are supplied with a shielding gas SG such that it exits through the shielding gas outlets SGA into the laser channel 5.

[0040] A laser beam LS is emitted by the laser beam emitter and, for example, guided by the welding optics onto a surface of section 2.1 of component 2. The laser beam LS can be moved such that its point of impact on the surface of section 2.1 rotates. The laser beam LS melts section 2.1 of component 2 completely and component 3 partially, so that after the molten area solidifies, the weld SV between components 2 and 3 is created.

[0041] During the laser welding process, excess shielding gas SG is discharged from laser channel 5 through the shielding gas outlet channels SGK.

[0042] This previously described process can be carried out successively for a large number of welded joints SV to be produced in a short cycle time due to the active cooling of the pressure piece 1, whereby temperature-related damage to the components 2, 3 when the pressure piece 1 is placed on them and temperature-related impairment can be effectively avoided. Reference symbol list 1 printing piece 2 components Section 2.1 Section 2.2 3 components 4 wall 4.1 Bowl 4.2 Bowl 5 laser channels 6.1 to 6.4 Shielding gas duct 7 Cooling channel F force KM cooling medium LS laser beam SG shielding gas SGA shielding gas outlet SGK shielding gas outlet channel SV welded joint

Claims

[1] Device for laser welding of components (2, 3) with at least one laser beam emitter and at least one pressure piece (1), which - is designed to be pressed against at least one of the components (2, 3), and - has a laser channel (5) through which a laser beam (LS) emitted by means of the laser beam emitter can be guided onto a surface of at least one of the components (2, 3), where - in a wall (4) surrounding the laser channel (5) and forming its outer surface, at least one shielding gas channel (6.1 to 6.4) is formed in an inner section facing the laser channel (5), which can be supplied with a shielding gas (SG) and has at least one shielding gas outlet (SGA) which leads through the wall (4) into the laser channel (5), - in the wall (4) in an outer section facing away from the laser channel (5) at least one cooling channel (7) is formed, which can be supplied with a cooling medium (KM), and - the wall (4) is formed as a two-shell structure, wherein an inner shell (4.1) forms the inner section of the wall (4) and coaxially surrounds the laser channel (5) and an outer shell (4.2) forms the outer section of the wall (4) and coaxially surrounds the laser channel (5) and the inner shell (4.1). [2] Device according to claim 1, characterized by , that at least one cooling channel (7) runs meanderingly in the wall (4) or runs in the wall (4) in such a way that it spirals around the laser channel (5) or coaxially surrounds the laser channel (5). [3] Device according to claim 1 or 2, characterized by , that at least one protective gas channel (6.1 to 6.4) coaxially surrounds the laser channel (5). [4] Device according to any one of the preceding claims, characterized by , that an outer circumference and / or an inner circumference of the wall (4) decreases / decreases from a first outer surface of the pressure piece (1) to a second outer surface opposite it, which is intended to be in contact with the at least one component (2, 3). [5] Device according to any one of the preceding claims, characterized by , that an outer shape and / or an inner shape of the wall (4) are frustoconical. [6] Device according to claim 5, characterized by , that the outer shape and / or the inner shape of the wall (4) are frustoconical or frustoelliptical [7] Device according to one of the preceding claims characterized by, that in a second outer surface which is provided for attachment to the at least one component (2, 3) end area of ​​the wall (4) facing at least one shielding gas outlet channel (SGK) is formed which completely penetrates the wall (4) from the laser channel (5) to an outer surface of the wall (4). [8] Device according to one of the preceding claims characterized by , that the pressure piece (1) is mechanically firmly connected to a welding optics unit. [9] Method for laser welding of components (2, 3) using a device according to one of the preceding claims, wherein - the components to be welded (2, 3) are positioned relative to each other in a welding position, - the pressure piece (1) is pressed against at least one of the components (2, 3), - the at least one shielding gas channel (6.1 to 6.4), which is formed in the double-shell wall (4) in the outer section facing the laser channel (5) and formed by means of the inner shell (4.1) coaxially surrounding the laser channel (5), is supplied with a shielding gas (SG) in such a way that it escapes through the shielding gas outlet (SGA) into the laser channel (5), - the at least one cooling channel (7), which is formed in the double-shell wall (4) in the outer section facing away from the laser channel (5) and formed by means of the outer shell (4.2) coaxially surrounding the laser channel (5) and the inner shell (4.1), is supplied with a cooling medium (KM), - a laser beam (LS) is emitted by means of the laser beam emitter and directed onto a surface of at least one of the components (2, 3) and - by means of the laser beam (LS) at least one of the components (2, 3) is melted in such a way that after a molten area has solidified, a weld connection (SV) is created between the components (2, 3).

Images