Welding apparatus and method for welding at least two components

Abstract

A welding apparatus (1) and method for welding at least two components (7) are described. The welding apparatus (1) includes an ultrasonic welding apparatus (3) and a laser welding apparatus (5), and is configured to use the ultrasonic welding apparatus (3) to ultrasonically weld the two components (7) together in a first area (21), and to use the laser welding apparatus (5) to laser weld the two components (7) together in a second area (23) that is narrower than the first area (21) and that is located within and / or adjacent to the outer periphery of the first area (21) during the ultrasonic welding process. For this purpose, the ultrasonic welding device (3) may have an ultrasonic sonotrode (9) and / or anvil (11) having a through opening (19) in a first area (21), and the laser welding device (5) may be configured to direct a laser beam (17) through the through opening (19) onto a second area (23) on the two components (7) in order to further weld the two components (7) together by laser welding.

Description

[Technical Field]

[0001] The present invention relates to a welding apparatus and method for welding at least two components together. [Background technology]

[0002] For a wide variety of technical purposes, it may be necessary to firmly bond two components together. For example, in the context of battery cell manufacturing, multiple thin metal films are typically bonded to each other and / or to metal sheets for good electrical conductivity and mechanical reliability.

[0003] The two components may be bonded together, for example integrally glued, to form a strong, mechanically high load-bearing bond between them. An integrally glued bond may be produced, for example, by welding the two components together.

[0004] A variety of techniques are known that can be used to weld components made of the same or different materials, each of which may require specific boundary conditions and / or offer specific advantages and disadvantages.

[0005] For example, it is known that components can be joined by so-called friction welding, in which the mating components rub against each other at the interface between the two components, and depending on boundary conditions, such as the pressure applied during friction and / or the extent or speed at which the two components are displaced relative to each other during friction, an integral adhesive bond between the components results.

[0006] A special form of friction welding is known as ultrasonic welding. In ultrasonic welding, two or more components to be welded, also known as base materials, are brought into contact with each other as mating surfaces and are subjected to contact movement with each other under slight pressure using high-frequency mechanical vibrations. Here, the vibrations may be generated by a sonotrode, which generates ultrasonic vibrations, typically with a frequency of 20 kHz to 50 kHz, and transmits them to at least one of the mating surfaces. Ultrasonic welding can be used not only to weld metal mating surfaces, but also to weld mating surfaces made of other materials, particularly plastics. In ultrasonic metal welding, the vibrations are typically applied horizontally to the mating surfaces, i.e., parallel to the surfaces of the mating surfaces, resulting in friction between the mating surfaces. Bonding occurs, for example, after substantial shearing of asperities and / or destruction of oxide layers due to the mating surfaces engaging and / or mating. This generally occurs through plastic flow, without necessarily melting the material. This can be particularly advantageous for welding films, thin metals, and / or wire. In addition to spot welding, seam welding is also possible with a rotating sonotrode. Ultrasonic welding is often characterized by very short welding times and high efficiency. Different materials can also be joined together. The components to be welded are usually only slightly heated in the welding area, so that the surrounding material is hardly damaged.

[0007] Laser welding, sometimes called laser beam welding, is another known welding technique. Laser welding, like friction welding, is typically performed without the addition of additional material. The laser radiation emitted by a laser is focused using an optical system. The abutting surfaces of the workpieces, i.e., the joining surfaces of the components to be welded, are located very close to the focal point of the optical system. In most cases, the position of the focal point relative to the component surfaces—either above or below—is an important welding parameter and also determines the weld penetration depth. The focal point typically has a diameter of a few tenths of a millimeter, resulting in a very high energy density when the laser used has a typical power level of several kilowatts. Absorption of the laser power causes a very rapid temperature rise at the component surfaces, exceeding the melting temperature of the metal used, resulting in the formation of a melt. Due to the high cooling rate, depending on the material, the weld seam formed by the melt becomes very hard and generally loses its toughness.

[0008] Various combinations of known welding methods have been developed for different applications.

[0009] For example, it has been proposed to locally reinforce a weld formed by a first welding method, e.g., ultrasonic welding, subsequently or previously by a weld made by another welding method, e.g., laser welding. In this way, the advantages that can be realized with each of these individual welding methods may be at least partially combined.

[0010] Additionally, various modifications of known welding methods have been developed for different applications.

[0011] For example, a laser welding method using ultrasonic vibrations is described in Patent Document 1. Similar methods are described in Patent Documents 2 and 3. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Chinese Patent Publication No. 107570872 [Patent Document 2] Chinese Patent Publication No. 108381039 [Patent Document 3] Chinese Patent Publication No. 108326429 Summary of the Invention [Problem to be solved by the invention]

[0013] There may be a need for a welding apparatus and a welding method for welding two components that can advantageously combine the properties of conventional welding techniques. In particular, there may be a need for a welding apparatus and a welding method that, first, allows for the joining of two components having advantageous electrical properties, in particular low electrical resistance values, and, second, allows for the realization of a weld that allows for a reliable mechanical connection of the components with relatively little effort in terms of equipment and / or costs. In particular, there may be a need for a welding apparatus and a welding method that is advantageously suited for welding thin metal films together and / or to metal sheets, and that can therefore be advantageously used, for example, in the context of manufacturing battery cells. [Means for solving the problem]

[0014] Such a need may be met by the subject matter of one of the independent claims. Advantageous embodiments of the invention are defined in the dependent claims and the following description.

[0015] According to a first aspect of the present invention, a welding apparatus is disclosed that includes an ultrasonic welding apparatus and a laser welding apparatus, wherein the welding apparatus is configured to ultrasonically weld at least two components together in a first area using the ultrasonic welding apparatus, and during the ultrasonic welding process, to laser weld the two components together in a second area using a laser welding apparatus, the second area being narrower than the first area and at least partially located within and / or adjacent to the periphery of the first area.

[0016] According to a second aspect of the present invention, which may be selectively configured as a special embodiment of the first aspect, a welding apparatus is proposed, which includes an ultrasonic welding apparatus and a laser welding apparatus. The ultrasonic welding apparatus includes an ultrasonic sonotrode and an anvil. The ultrasonic sonotrode and anvil are arranged opposite and spaced apart from each other, enclosing a working volume between the ultrasonic sonotrode and the anvil, in which at least two components to be welded are to be placed during ultrasonic welding. The laser welding apparatus includes a laser that emits a laser beam. The ultrasonic sonotrode and / or the anvil have adjacent through-openings on and / or within a first area. The ultrasonic sonotrode and the anvil are configured to contact the two components in the first area with their contact surfaces from both sides during the ultrasonic welding process and weld the two components together by ultrasonic welding. The laser welding apparatus is further configured to direct the laser beam through the through-opening to a second area on the two components to weld the two components together by laser welding.

[0017] According to a third aspect of the present invention, a method for welding at least two components is disclosed, wherein the two components are welded together in a first area by ultrasonic welding, and during the ultrasonic welding process the two components are welded together in a second area by laser welding, the second area being narrower than the first area and located within the periphery of the first area.

[0018] Without limiting the scope of the present invention in any way, the intent and possible features of embodiments of the present invention can be seen as being based, inter alia, on the concepts and discoveries described below. In the following, possible features and advantages of embodiments of the present invention will be described primarily in relation to their application to the manufacture of battery cells. However, this should not exclude that embodiments of the present invention can also be used for other purposes.

[0019] In the manufacture of battery cells, multiple thin metal films must be regularly bonded to each other and / or to a metal sheet that serves as a substrate. Herein, the metal film connects to the electrodes within the battery cell and typically has a very thin thickness of 5 μm to 30 μm. Typically, the metal film is composed of aluminum, with a thin aluminum oxide layer on the surface. The metal sheet may be part of the battery cell's externally accessible electrical contacts and / or may be bonded to one of the battery cell's externally accessible electrical contacts. Typically, the metal sheet is substantially thicker than the metal film, having a thickness of several hundred μm, e.g., 300 μm to 2 mm. To achieve lower series resistance, the metal sheet is often composed of copper or a copper-containing alloy.

[0020] Traditionally, metal films are often joined to each other and / or to metal sheets by laser welding. A high-power laser beam is directed onto the metal film and / or sheet to rapidly melt the deposited metal and subsequently solidify it, forming a strong interlocking bond between the components. Rapid melting of the metal allows for high bond strength. Furthermore, penetration contact is possible in the area of ​​the laser weld. However, during laser welding, it must also be ensured that the metal films are separated from each other by a very small gap, since otherwise there is a risk that the laser beam will not weld the metal films together as desired but will instead pass through some of the metal films. It has also been observed that the metal melted during laser welding is harder than the surrounding metal after subsequent solidification. This, or the associated weakness, can lead to fractures, cracks, etc. in the area adjacent to the laser weld, thus potentially causing electrical and / or mechanical bond failure between the two components.

[0021] As an alternative to using laser welding techniques, metal films and / or metal sheets may be joined by ultrasonic welding. Ultrasonic welding can achieve large bond areas with very high quality in terms of electrical properties, allowing for the transmission of large currents through the weld site. However, the mechanical bond strength that can be achieved by ultrasonic welding is typically lower than that of laser welding.

[0022] It has been recognized that the advantages achievable first by laser welding and second by ultrasonic welding can be combined and / or the disadvantages associated with each welding technique can be reduced in that a large area weld initially formed by ultrasonic welding can then be reinforced at one or more smaller area locations by laser welding.

[0023] In the present invention, it has been discovered that the two welding techniques of laser welding and ultrasonic welding can be more advantageously combined with one another if they are performed substantially simultaneously and / or overlapping in time, rather than being performed one after the other in succession.

[0024] To enable such simultaneous ultrasonic and laser welding, the ultrasonic welding device used in the welding apparatus according to the present invention may be configured to ultrasonically weld two components to be welded together in a first area, i.e., a first surface region on the boundary area between two adjacent components. For this purpose, the ultrasonic sonotrode and anvil of the ultrasonic welding device may be configured so that during the ultrasonic welding process, the ultrasonic sonotrode and anvil at least lightly press the two components contained in the working volume between the ultrasonic sonotrode and anvil against each other in the region of the first area, exciting the two components to vibrate relative to each other. The vibrations may be excited preferably in a plane parallel to the boundary area between the components and / or in a plane parallel to the surfaces of the components against which the sonotrode abuts.

[0025] The ultrasonic sonotrode may be configured in the same or similar manner as a conventional ultrasonic sonotrode with respect to its outer dimensions, its vibration-inducing components, and other functional and / or function-related properties. The anvil may also be configured in the same or similar manner as a conventional anvil with respect to its outer dimensions and other structural and / or functional properties.

[0026] However, the ultrasonic welding device used in the welding apparatus described herein preferably differs from conventional ultrasonic welding devices in that at least the ultrasonic sonotrode and / or anvil are provided with through openings. In other words, the ultrasonic sonotrode and / or anvil may be discrete solid components, but rather may have, for example, a through hole in the center.

[0027] The through opening may have a cross-sectional area significantly smaller than the area over which the sonotrode extends relative to the components to be welded. For example, the through opening may have a cross-sectional area of ​​less than 10 mm, preferably less than 2 mm, but more than 0.1 mm. The cross section of the through opening may be circular or rectangular, or may have any other shape. In particular, the through opening may be cylindrical.

[0028] The through opening herein extends through the ultrasonic sonotrode and / or the anvil, forming a linear passageway between a first surface of the ultrasonic sonotrode and / or the anvil and a second surface disposed on the opposite side of the ultrasonic sonotrode and / or the anvil.

[0029] The through-opening extends transversely to the surface adjacent to the components to be welded, where the ultrasonic sonotrode and / or anvil are housed within the working volume. Here, the through-opening opens within the periphery of the first area to be welded by the ultrasonic welding device. Therefore, the contact surface of one of the components to be welded, contacted by the ultrasonic sonotrode and / or anvil, is not continuous, but has a partial area adjacent to the through-opening, where the sonotrode and / or anvil do not contact the surface of the associated component. In other words, the contact surface may be annular, i.e., it may extend over a circumferentially surrounded surface or may encompass a partial area not contacted by the sonotrode. The outer contour of the contact surface and / or the cross-section of the through-opening may have any desired geometric shape, i.e., for example, circular, angular, particularly square, or rectangular.

[0030] Thus, the laser welding device of the welding device described herein may be configured to direct a laser beam emitted by the laser of the laser welding device through the described through-hole to a second area on the two components to be welded. In particular, laser welding may be performed using so-called laser spot welding. The second area is within a partial area not directly contacted by the sonotrode and / or anvil, i.e., within the aforementioned cutout in the contact surface contacted by the sonotrode. Thus, using a high-energy laser beam, the two components can be locally laser welded in the second area. In particular, this laser welding may be performed in the second area while the ultrasonic welding device simultaneously performs ultrasonic welding in a larger first area surrounding the second area.

[0031] Depending on the boundary conditions prevailing for a particular configuration of use and / or the requirements imposed on the weld to be formed of two or more components, it may be advantageous to provide a through-opening in the ultrasonic sonotrode and direct the laser beam of the laser welding device through this through-opening to the surface of the component directed to the ultrasonic sonotrode. However, in other configurations of use, it may be advantageous to provide a through-opening in the anvil and thus direct the laser beam of the laser welding device through the anvil to the surface of the component facing opposite the ultrasonic sonotrode. In still other configurations, it may be advantageous to provide through-openings in both the ultrasonic sonotrode and the anvil and use the laser beam to create a laser weld on both surfaces of the component facing away from each other.

[0032] In principle, it is also possible for the laser welding device to direct the laser beam not through an opening through the ultrasonic sonotrode or anvil, but rather from the side onto the components to be welded, where the laser beam may be directed in the plane of the components to be welded and / or parallel or slightly tilted to this plane.

[0033] In the first-mentioned configuration, where the laser beam is directed through the through opening to the ultrasonic sonotrode and / or the anvil, the second area is preferably located entirely within the periphery of the first area, whereas in the second-mentioned configuration, where the laser beam is directed from the side to the components to be welded, the second area may be located at least partially outside the first area, but adjacent to the outside of the first area. In other words, in this second-mentioned configuration, the second area and the first area may also at least partially overlap, and both areas may be at least closely adjacent to each other, i.e., the lateral distance between the two areas should be minimal, in particular less than 2 mm, for example.

[0034] According to one embodiment of the present invention, the welding device may further include a controller for controlling the simultaneous operation of the ultrasonic welding device and the laser welding device.

[0035] In other words, the welding device may have a control device that allows the operation of the ultrasonic welding device and the operation of the laser welding device of the welding device to be appropriately coordinated with each other in time. To this end, the control device must typically be able to communicate with the ultrasonic welding device and the laser welding device. For example, the control device may control both the power supply to the ultrasonic welding device and the power supply to the laser welding device.

[0036] According to a more specific embodiment of the present invention, the control device may be configured to perform laser welding by controlling the laser welding device while ultrasonic welding is performed by controlling the ultrasonic welding device.

[0037] In other words, the control device may control the ultrasonic welding device to excite the ultrasonic sonotrode to vibrate within a first period of time to ultrasonically weld two components together in a first area. Furthermore, the control device may operate the laser welding device within a second period of time to locally weld the two components together in the second area by emitting a laser beam. The first and second periods should be simultaneous or at least overlapping in time so that laser welding occurs while ultrasonic welding is being performed. Typically, the second period during which laser welding is performed is shorter than, or at most equal to, the first period during which ultrasonic welding is performed. Thus, for example, ultrasonic welding may already have begun before laser welding is performed, and / or ultrasonic welding may continue temporarily after the laser welding is completed. In principle, the first period may begin before the second period of time, and the first period may end before, simultaneously with, or after the second period of time. Alternatively, both periods may start simultaneously, with the first period ending before, simultaneously with, or after the second period. Further alternatively, the second period may start before the first period, with the first period ending before, simultaneously with, or after the second period. Typical durations of the first and / or second periods range from a few tens of milliseconds to a few seconds, for example, 0.05 seconds to 1 second, preferably 0.1 seconds to 0.5 seconds.

[0038] Using the welding apparatus described herein, welding of two components can be performed simultaneously by ultrasonic welding and by laser welding in adjacent first and second areas, thereby realizing one or more of the advantages described below.

[0039] In particular, in the first area, a large bond zone may be produced, as is typical with ultrasonic welding, within which a low internal electrical resistance may be achieved, which may be the high quality weld bond level produced by ultrasonic welding and therefore have a lower electrical resistance than would occur with a weld bond produced by laser welding alone.

[0040] Additionally, at least in the second area, a bond strength may be achieved that is greater than the bond strength typically achievable by ultrasonic welding, as may typically be achieved during laser welding.

[0041] There, the entire welding process may be accomplished in a single operation. Furthermore, the entire welding process may be performed using a single welding device.

[0042] It is also believed that when laser welding and ultrasonic welding are performed simultaneously, boundary conditions favorable to laser welding are created. In particular, it is believed that the melt generated in a short time during laser welding due to the energy input by the laser into the components to be welded can be homogenized due to the vibrations simultaneously generated during ultrasonic welding. Homogenization can, for example, reduce local temperature gradients within the melt and / or reduce other differences between locally prevalent physical properties within the melt. This homogenization can favorably affect the weld site created by laser welding after subsequent solidification.

[0043] Furthermore, because the laser welding is performed simultaneously with the ultrasonic welding, it has been found that the laser power used for the laser welding is often much less than if the components were joined by laser welding alone. The simultaneous ultrasonic welding appears to provide a specific energy input to the material at and / or adjacent to the laser weld site, facilitating the laser welding.

[0044] Therefore, the laser welding device is configured to emit laser light having a power of less than 3 kW, preferably less than 1.5 kW, according to one embodiment of the laser welding device.

[0045] Such relatively low laser power levels may be sufficient, especially in conjunction with simultaneous ultrasonic welding, to weld components having substantial mass, i.e., components in the form of metal sheets as well as thin films. Conventionally, for this purpose, lasers with laser powers of, for example, 4 kW or more must be used. Using a lower-power laser can reduce both the cost of the laser and the cost of the laser's energy consumption.

[0046] Simultaneous or overlapping ultrasonic welding may preferably be performed at a relatively low power level, for example, less than 12 kW or less than 8 kW, preferably less than 6 kW or even less than 4 kW. Thus, the two welding techniques, ultrasonic welding and laser welding, can operate at significantly lower power levels when they overlap than when they are performed separately.

[0047] According to one embodiment of the present invention, the laser welding apparatus may be configured to direct the laser beam onto the second area at an oblique angle relative to the contact surface.

[0048] In other words, the laser of the laser welding device may be positioned and oriented so that the laser beam emitted from the laser welding device is not perpendicular to the second area, but rather strikes the second area and / or the contact surface including the second area at an oblique angle of, for example, 1° to 89°, preferably 30° to 85°, more preferably 50° to 80°.

[0049] Such oblique incidence of the laser beam can be advantageous in that the weld zone created by laser welding does not necessarily extend perpendicular to the outer surfaces of the components to be welded, but rather extends obliquely into the components, for example, through the components in the case of multiple thin films being welded. Under mechanical loads acting in a certain direction, such an obliquely oriented weld zone may result in higher strength and / or stronger cohesion of the welded components than in the case of a perpendicularly oriented weld zone. In particular, the bond area between the components to be welded in the case of oblique laser beam incidence may be larger than in the case of normal incidence.

[0050] According to one embodiment of the present invention, the through openings extending through the ultrasonic sonotrode and / or the anvil may be oriented obliquely relative to the contact surface.

[0051] In principle, it may be possible to pass the laser beam obliquely through the contact surface using a through-hole extending perpendicular to the contact surface if the through-hole has a sufficiently large lateral dimension, i.e., if the through-hole has a sufficiently large diameter. However, it may be advantageous to provide a through-hole with the smallest possible lateral dimension, for example, to avoid excessive mechanical weakening of the ultrasonic sonotrode. In particular, it may be advantageous to provide a through-hole with a lateral dimension that approximately corresponds to or is slightly larger than the diameter of the laser beam delivered through the through-hole. Therefore, it may be advantageous to also provide the through-hole with an oblique passage through the sonotrode and / or anvil to allow the laser beam to impinge obliquely on the contact surface. The angle at which the through-hole is oriented with respect to the contact surface with the component to be welded may here approximately correspond to the angle at which the laser beam is directed to the second area.

[0052] Alternatively, the through-opening may be configured conically or biconically so that the laser beam can pass obliquely through the through-opening to the contact surface without, nevertheless, excessively reducing the mechanical stability of the ultrasonic sonotrode and / or anvil having the through-opening.

[0053] According to one embodiment of the present invention, the ultrasonic sonotrode and / or the anvil may have a plurality of through-openings in the first area, and the laser welding device may be configured to direct a laser beam through each of the plurality of through-openings to a plurality of second areas on the two components to additionally weld the two components together by laser welding.

[0054] In other words, the welding device may be configured to, in addition to welding the components by ultrasonic welding, create multiple laser weld sites, in that rather than joining the components at only a single site by laser welding, multiple laser beams are directed at multiple second areas on the components.

[0055] Creating multiple laser weld sites can increase the mechanical strength of the formed weld bond. In particular, two, three, four, or more laser weld sites can be formed on multiple adjacent and / or spaced apart second areas.

[0056] For this purpose, a single laser beam emitted by a laser may be sequentially directed to each of the second areas to form a laser weld site in each of the second areas. For example, the laser beam may be sequentially deflected using an appropriate optical system. Alternatively, the single laser beam may be divided into multiple partial laser beams using an appropriate optical system, and then each of these partial laser beams may be directed to one of the multiple second areas to form a laser weld site in one of the multiple second areas. As a further alternative, multiple lasers may be used to generate multiple laser beams, and each of these laser beams may be directed to one of the multiple second areas.

[0057] According to one embodiment, the laser welding device may be configured to emit a laser beam for laser welding using laser light having a wavelength of less than 600 nm, preferably less than 500 nm, which means that in the described welding method, laser light having a wavelength in the above-mentioned range may be used for laser welding.

[0058] This embodiment is based on the recognition that certain components and / or components made of certain materials can be laser welded particularly advantageously with shorter wavelength laser light. Traditionally, powerful lasers with laser light in the red or infrared wavelength range, i.e., primarily with wavelengths above 700 nm, have been used for laser welding, particularly metal components. However, it has been recognized that components made of non-ferrous metals, such as copper or copper alloys, can be welded advantageously with shorter wavelength laser light. In particular, green laser light, i.e., laser light with a wavelength of approximately 500-600 nm, or even shorter wavelength blue light, i.e., laser light with a wavelength of approximately 400-500 nm, can produce beneficial properties in the laser weld created by the laser light. In particular, short-wavelength laser light can be absorbed very efficiently by the materials to be welded, which can have the beneficial effect of enabling rapid melting of the materials. Rapid melting, among other benefits, can result in non-ferrous metals being melted without vaporization, resulting in greater stability of the weld pool created by melting.

[0059] In general, for laser welding, lasers with different characteristics regarding the emitted laser light and / or beam shape can be used. For example, depending on the prevailing boundary conditions and the laser weld to be formed, lasers that continuously emit a laser beam, i.e., so-called CW (continuous wave) lasers, can be used. Such CW lasers can typically form a laser weld within tens to hundreds of milliseconds, for example, within 0.1 to 0.5 seconds. Alternatively, lasers that emit pulsed laser beams can be used. The pulse duration is application-specific and can be selected in the microsecond, nanosecond, picosecond, or even femtosecond range.

[0060] The welding method described in addition to the welding apparatus according to the third aspect of the invention may in particular be carried out using a welding apparatus according to an embodiment of the first or second aspect of the invention, and therefore the features described for the welding apparatus may be used in the welding method as well.

[0061] For example, in a welding method according to one embodiment, the components to be welded may be multiple metal films.

[0062] It is envisioned that the described combination of ultrasonic welding and simultaneous laser welding will enable very beneficial results, particularly when welding thin metal films, such as aluminum films, such as those required in the manufacture of battery cells.

[0063] Laser welding alone, which has been used for this purpose in the past, has proven difficult to achieve by locally melting multiple thin metal films simultaneously in a suitable manner. In particular, there was a risk that the metal films would be penetrated by the laser beam rather than being welded by being locally melted. In particular, pure laser welding was sensitive to the presence of voids between the welded metal films. Furthermore, welds formed by laser welding often have relatively poor electrical properties, particularly a relatively high electrical resistance.

[0064] On the other hand, while the use of ultrasonic welding alone to join metal films has provided a good electrical bond, the mechanical bond formed by the use of ultrasonic welding alone has often been poor.

[0065] In the proposed combination of ultrasonic welding and simultaneous laser welding, metal films are pressed together and welded in a first area by an ultrasonic welding device, while in a second area the abutting metal films can be joined together in a low-risk manner by laser welding, thereby forming an integrally adhesive bond between the metal films that is highly electrically conductive and yet mechanically load-bearing.

[0066] According to an alternative embodiment, in the welding method, the components to be welded may be at least one metal film and at least one metal sheet.

[0067] The task of welding one or more thin metal films to at least one metal sheet may arise, particularly during the manufacture of battery cells. The thin metal film may be bonded to an electrode of a winding inside the battery cell and then welded to a metal sheet that can also serve as an externally accessible terminal. The metal sheet inside the battery cell has a thickness many times greater than the metal film. With conventional laser welding, this can cause problems in that the material of the metal sheet melts more slowly or more slowly than the material of the metal film. As a result, depending on the characteristics of the laser used for laser welding, damage to the metal film may occur and / or an inappropriate weld may be created. In the above-mentioned application, it is particularly anticipated that a combination of ultrasonic welding and simultaneous laser welding can advantageously and reliably form a weld with both good electrical and mechanical properties.

[0068] According to one embodiment, in the welding method, the at least one metal film and / or the at least one metal sheet may consist mainly of copper.

[0069] In particular, the metal film and / or metal sheet may be composed entirely of copper or a copper alloy. Such copper-containing components may have very low series resistance, but are often difficult, at best, to process with conventional welding methods. In the welding methods described herein, for example, by using a short-wave laser with simultaneous ultrasonic welding, multiple copper-containing components may also be advantageously welded to each other and / or to other metal components.

[0070] It should be noted that possible features and advantages of embodiments of the present invention are described herein partly with respect to welding apparatus constructed in accordance with the present invention and partly with respect to welding methods in accordance with the present invention. Those skilled in the art will recognize that features described with respect to individual embodiments may be suitably transferred, adapted, and / or exchanged in a similar manner with other embodiments to arrive at further embodiments of the present invention, and in some cases, to arrive at synergistic effects. [Brief explanation of the drawings]

[0071] Advantageous embodiments of the invention are described in more detail below with reference to the accompanying drawings, in which neither the drawings nor the description should be considered limiting in any way.

[0072] [Figure 1] 1 is a highly schematic illustration of a welding apparatus according to one embodiment of the present invention; [Figure 2] 1 is a schematic diagram of a sonotrode and anvil of an ultrasonic welding device of a welding device according to one embodiment of the present invention; [Figure 3] 2 is a cross-sectional view of a sonotrode and anvil of an ultrasonic welding device of a welding device according to one embodiment of the present invention. [Figure 4] 2 is a plan view of membrane components welded together using a welding method according to one embodiment of the present invention; [Figure 5] 10 is a cross-sectional view through a sonotrode and anvil of an ultrasonic welding device of a welding device according to an alternative embodiment of the present invention. [Figure 6] 10 is a plan view of membrane components welded together with a welding method according to an alternative embodiment of the present invention;

[0073] The drawings are generally schematic and not to scale. The same reference signs in different drawings refer to the same or similarly acting features. DETAILED DESCRIPTION OF THE INVENTION

[0074] 1 shows a welding apparatus 1 according to one embodiment of the present invention. The welding apparatus 1 includes an ultrasonic welding apparatus 3 and a laser welding apparatus 5. The operation of the ultrasonic welding apparatus 3 and the operation of the laser welding apparatus 5 may each be controlled by a control device 25 within the apparatus.

[0075] The welding apparatus 1 is internally configured to accommodate at least two components 7 to be welded within a working volume 13 and to simultaneously weld the at least two components 7 together in both a first area 21 using ultrasonic welding and a second area 23 using laser welding.

[0076] As shown in additional detail in FIG. 2 , the ultrasonic welding apparatus 3 includes an ultrasonic sonotrode 9 and an anvil 11 positioned on opposing sides of the working volume 13. The ultrasonic welding apparatus 3 further includes an ultrasonic generator 33 capable of generating ultrasonic vibrations at a typical frequency of 20 kHz to 50 kHz. The ultrasonic vibrations may then be transmitted to the ultrasonic sonotrode 9 as mechanical vibrations by a transducer 31 and a booster 27. The booster 27 and the ultrasonic sonotrode 9, which is mechanically coupled to the booster 27, may be moved to the working volume 13 using an actuator 29. In this manner, the uneven contact surface 35 of the ultrasonic sonotrode 9 may be pressed against a surface facing the sonotrode of one of the components 7 to be welded (a component not shown in FIG. 2 for clarity). In this manner, the component 7 to be welded may be clamped between the contact surface 35 of the ultrasonic sonotrode 9 and the anvil 11.

[0077] The ultrasonic welding apparatus 3 described in this specification differs from conventional ultrasonic welding apparatuses in that, in particular, the ultrasonic sonotrode 9 of the ultrasonic welding apparatus 3 and / or the anvil 11 of the ultrasonic welding apparatus 3 are provided with a through opening 19 through which the laser beam 17 emitted by the laser 15 of the laser welding apparatus 5 can be directed into the working volume 13 and, consequently, onto the component 7 contained in the working volume 13.

[0078] In the illustrated example, the through opening 19 is formed in the ultrasonic sonotrode 9. The through opening 19 in the ultrasonic sonotrode 9 extends transversely to the contact surface 35, through the entire sonotrode head 10. Thus, in the described example, a laser 15 positioned above the ultrasonic sonotrode 9 can direct a laser beam 17 of the laser 15 through the through opening 19 to a second area 23 on the upwardly facing surface of the upper component 7 to be welded.

[0079] 3 shows a cross-sectional view of the ultrasonic sonotrode 9 and anvil 11 of the ultrasonic welding apparatus 3. The working volume 13 may contain the components 7 to be welded in the form of a plurality of thin metal films 37. For clarity, only four metal films 37 are shown, but in practice, a much larger number of such metal films 37 may be welded together.

[0080] FIG. 4 shows a plan view of the component 7 to be welded.

[0081] During the welding process, the metal films 37 are pressed against the opposing contact surfaces of the anvils 11 by the uneven contact surfaces 35 of the ultrasonic sonotrode 9, so that they abut against each other. At this time, the ultrasonic sonotrode 9 transmits mechanical ultrasonic vibrations into the stacked metal films 37 via the uneven contact surfaces 35, so that the stacked metal films 37 are joined together by ultrasonic welding.

[0082] During ultrasonic welding, the laser beam 17 is further directed through the through opening 19 of the ultrasonic sonotrode 9. In this way, a weld site 39 joining the components 7 is formed by ultrasonic welding and laser welding at the same time.

[0083] As a result of the through opening 19 provided in the ultrasonic sonotrode 9, the contact surface 35 of the ultrasonic sonotrode 9 has a notch provided by the through opening 19 not over the entire area but in the center of the contact surface 35. Thus, during the welding process, the ultrasonic sonotrode 9 can contact a wide first area 21 on the component 7 with the annular contact surface 35 of the ultrasonic sonotrode 9 and can join multiple components 7 in the first area 21 by ultrasonic welding. In the region of the notch, the laser beam 17 can reach the second area 23 and form a substantially point-like weld 39 in the second area 23 by laser welding. The second area 23 is here significantly narrower than the first area 21 and is located within the first area 21, i.e. is annularly surrounded by the first area 21.

[0084] 5 and 6 show a cross-sectional view of an alternatively configured ultrasonic sonotrode 9 of the ultrasonic welding device 3 and a plan view of the component 7 to be welded with the ultrasonic sonotrode 9. FIG.

[0085] In this case, the component 7 to be welded is a plurality of metal films 37 and a metal sheet 43 that is significantly thicker than the metal films 37. The metal films 37 and the metal sheet 43 may be made of different materials. In particular, the metal films 37 may be made of aluminum, for example, while the metal sheet 43 may be made of copper or a copper alloy.

[0086] In this example, the ultrasonic sonotrode 9 has a plurality of through openings 19′, 19″. In the illustrated example, the laser beam 17 is split into a plurality of separate laser beams 17′, 17″ using a beam splitter 41. To create a plurality of weld sites 39 in a plurality of second areas 23 using laser welding, each of the laser beams 17′, 17″ is directed through one of the through openings 19′, 19″ and onto one of the plurality of second areas 23.

[0087] Finally, it should be noted that terms such as "having" and "comprising" do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above exemplary embodiments may also be used in combination with other features or steps of other of the above exemplary embodiments. Reference signs in the claims should not be construed as limiting. [Explanation of symbols]

[0088] 1. Welding equipment 3 Ultrasonic welding equipment 5. Laser welding equipment 7 Components to be welded 9 Ultrasonic Sonotrode 10 Sonotrodehead 11 Anvil 13 Working volume 15 Laser 17 Laser Beam 19 Through opening 21 First Area 23 Second Area 25 Control device 27 Booster 29 Actuators 31 Converter 33 Ultrasonic Generator 35 Uneven contact surface 37 Metal Film 39 Welding area 41 Beam Splitter 43 Metal Sheet

Claims

1. an ultrasonic welding device (3), and Laser welding equipment (5) A welding device (1) having The welding device (1) is configured to use the ultrasonic welding device (3) to weld together at least two components (7) formed by a plurality of metal films (37) or at least one metal film (37) and at least one metal sheet (43) by ultrasonic welding in a first area (21), and to weld together the at least two components (7) by laser welding in a second area (23) that is narrower than the first area (21), at least partially within the periphery of the first area (21), and / or that is adjacent to the periphery of the first area (21) with a distance of less than 2 mm from the periphery.

2. the ultrasonic welding device (3) comprises an ultrasonic sonotrode (9) and an anvil (11), the ultrasonic sonotrode (9) and the anvil (11) being arranged opposite and spaced apart from each other and enclosing therebetween a working volume (13) in which the at least two components (7) to be welded are placed during the ultrasonic welding process; The laser welding device (5) has a laser (15) that emits a laser beam (17), the ultrasonic sonotrode (9) and / or the anvil (11) have a through opening (19) in the first area (21); the ultrasonic sonotrode (9) and the anvil (11) are configured to contact the at least two components (7) in the first area (21) from both sides at their contact surfaces during the ultrasonic welding process, and to weld the at least two components together by the ultrasonic welding; 2. The welding device (1) of claim 1, wherein the laser welding device (5) is further configured to direct the laser beam (17) through the through opening (19) to the second area (23) on the at least two components (7) to weld the at least two components (7) together by the laser welding.

3. 3. The welding device (1) according to claim 2, further comprising a control device (25) for controlling the simultaneous operation of the ultrasonic welding device (3) and the laser welding device (5).

4. 4. The welding device according to claim 3, wherein the control device (25) is configured to perform the laser welding by controlling the laser welding device (5) while performing the ultrasonic welding by controlling the ultrasonic welding device (3).

5. 5. The welding device according to claim 2, wherein the laser welding device (5) is configured to direct the laser beam (17) onto the second area (23) at an oblique angle to the contact surface.

6. 6. The welding device according to claim 2, wherein the through openings (19) are oriented obliquely towards the contact surface.

7. the ultrasonic sonotrode (9) and / or the anvil (11) have a plurality of through-openings (19', 19'') in the first area (21); 7. The welding device according to claim 2, wherein the laser welding device is configured to direct one of a plurality of laser beams through each one of the plurality of through openings to a plurality of second areas on the at least two components to further weld the at least two components together by the laser welding.

8. 8. The welding device according to claim 1, wherein the laser welding device (5) is configured to emit the laser beam (17) for the laser welding using laser light having a wavelength of less than 600 nm.

9. The welding device according to any one of claims 1 to 8, wherein the laser welding device (5) is configured to emit laser light having an output of less than 3 kW for the laser welding.

10. 1. A method for welding at least two components (7) together, wherein the at least two components (7), formed by a plurality of metal films (37) or by at least one metal film (37) and at least one metal sheet (43), are welded in a first area (21) by ultrasonic welding, and during the ultrasonic welding, the at least two components (7) are welded together in a second area (23), which is narrower than the first area (21) and is located within the periphery of the first area (21), by laser welding.

11. 11. The method of claim 10, wherein the at least one metal film (37) and / or the at least one metal sheet (43) consists primarily of copper.

12. 12. The method according to claim 10 or 11, wherein for the laser welding, laser light having a wavelength of less than 600 nm is used.

13. The method according to any one of claims 10 to 12, wherein the method is performed by a welding device (1) according to any one of claims 1 to 9.

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