Molded body for a sheet metal laser welding clamp

Abstract

A sheet metal laser welding clamp comprises a body transparent to the laser wavelengths, which has a laser welding section, wherein the laser welding section includes an upper solid section for allowing the laser wavelengths to pass through to a lower hollow section for forming an interface with an upper sheet metal panel within a stack of sheet metal panels during a laser welding operation.

Description

TECHNICAL AREA

[0001] The disclosure relates to a shaped body for a sheet metal laser welding clamp and a method for using the same to join sheet metal panels. BACKGROUND

[0002] Laser welding is a technique used to join multiple sheet metal panels using a laser beam. The beam provides a concentrated heat source, allowing for narrow, deep welds and high heating and cooling rates. In many applications, the sheet metal panels must be aligned and in continuous contact along the entire length of the laser weld to ensure a proper weld. Various welding clamps have been designed to achieve this alignment.

[0003] WO 00 / 66 345 A2 describes a method for welding thermoplastic parts by applying a laser, wherein an upper body made of highly transparent hard plastic material is used to transfer the laser beam to the thermoplastic parts to be welded, while the thermoplastic parts are fixed by a clamp. SUMMARY

[0004] A shaped body according to claim 1 is disclosed. The shaped body is transparent to the laser wavelengths and has a laser welding section, wherein the laser welding section comprises an upper solid section for transmitting the laser wavelengths to a lower cavity section for forming an interface with a sheet metal panel during a laser welding operation. The material of the shaped body has a coefficient of thermal expansion of 0.54 to 3.2 × 10⁻⁶ K⁻¹, measured at 20 °C. The lower cavity section can have an axial direction along its length. The lower cavity section can have a profile along its length. The profile of the lower cavity section can be constant along its length. The profile of the lower cavity section can be a substantially circular half-profile. The profile of the lower cavity section can be a trapezoidal profile.

[0005] The lower cavity section may have a surface containing protrusions that can be approximately 0.1 µm to approximately 0.015 mm long. The sheet-plate laser welding clamp may contain an anti-reflective material that is in contact with the surface of the upper solid section of the laser welding section. The laser welding section may contain a low-absorbing material.

[0006] In a further embodiment, a shaped body according to claim 7 is disclosed, which is transparent to the laser wavelengths and comprises a laser welding section and multiple circumferential walls. The laser welding section includes an upper solid section for transmitting the laser wavelengths to a lower cavity section for forming an interface with a sheet metal panel during a laser welding operation. The laser welding section further comprises one or more channels extending from the lower cavity section to one or more of the multiple circumferential walls and adjacent to the sheet metal panel. The lower cavity section and the one or more channels can each have a profile along their length. The profiles of the lower cavity section and the one or more channels can be constant. The cavity section and the one or more channels can each have an axial direction along their length.The axial directions of the lower cavity section and the one or more channels can be aligned. The one or more channels can contain one or more interconnected channels.

[0007] A method for laser welding multiple sheet metal panels according to claim 12 is disclosed. The method may include the steps of clamping multiple sheet metal panels together with a clamp having a transparent body and a cavity, and transmitting laser light through the body and the cavity onto the multiple sheet metal panels to form a weld at a weld point of the multiple sheet metal panels. The transparent body is transparent to the laser wavelengths. The transmitting step may form molten metal splashes from the multiple sheet metal panels. The transmitting step may further include collecting the molten metal splashes within the cavity. The transmitting step may generate a gas within the cavity and further include outgassing the gas from the cavity. The outgassing step may include releasing the gas from the cavity through one or more channels. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a perspective schematic view of a laser welding clamp and a number of sheet metal panels to be welded according to one embodiment; Fig. 2A shows a side view of the laser welding clamp. Fig. 1 represents an alternative profile; Fig. 2B shows a side view of the laser welding clamp. Fig. 1 represents an alternative profile and thickness of the sheets; Fig. Figure 3 shows a perspective schematic view of a clamp having a cavity and a number of channels, according to one embodiment; Fig. Figure 4 shows a view of the clamp. Fig. 3 from the bottom; Fig.Figure 5A shows a schematic side view of the terminal and a number of panels overlapping on opposite sides, according to one or more embodiments; Fig. Figure 5B shows a schematic side view of a clamp and a number of panels overlapping on the same side, according to at least one embodiment; Fig. Figure 6A illustrates a perspective schematic view of a clamp having a cavity that extends partially through the length of the lower cavity section, according to one or more embodiments; Fig. 6B shows a view of the terminal. Fig. 6A from below; and Fig. 6C presents a view of an alternative embodiment of the terminal according to Fig. 6B, which contains a number of channels, is shown from below. DETAILED DESCRIPTION

[0008] The embodiments of the present disclosure are described herein. It is understood, however, that the disclosed embodiments are merely examples and that other embodiments may take different and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show the details of particular components. Therefore, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching a person skilled in the art to use the present invention in various ways.As the average person skilled in the field recognizes, various features illustrated and described with respect to any of the figures can be combined with features illustrated in one or more other figures to create embodiments not explicitly illustrated or described. The combinations of the illustrated features provide representative embodiments for typical applications. However, various combinations and modifications of the features, consistent with the teachings of this disclosure, may be desirable for particular applications or implementations.

[0009] Except where expressly stated, all numerical quantities in this description that indicate dimensions or material properties are to be understood as modified by the word "approximately" when describing the broadest scope of protection of the present disclosure.

[0010] The first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation here and accordingly to the normal grammatical variations of the abbreviation initially defined. Unless explicitly stated otherwise, a measurement of a property is determined by the same technique referenced before or after for the same property.

[0011] Laser welding is a high-energy process used to join multiple sheet metal panels using a laser beam. The laser beam is directed onto the weld surface. At the weld surface, the concentrated light energy is converted into heat energy. This causes the surface to melt, and the heat propagates through the weld joint due to thermal conductivity. To achieve adequate mechanical properties of the weld in certain applications, the sheet metal panels must be in continuous contact and precisely aligned along the entire length of the laser weld. This prevents gaps between the panels, which can lead to a weld of insufficient strength. Various laser clamps have been developed to maintain contact between the sheet metal panels.An example of a laser welding clamp is a clamp in US Patent No. 4,847,467, the disclosure of which is incorporated herein by reference.

[0012] The previously developed clamps suffer from a number of disadvantages. For example, these clamps do not address the formation of weld spatter (spatter) at the weld point. Splash refers to droplets of molten metal ejected from the weld area. There has been significant interest in reducing spatter during laser welding, especially pulsed laser welding, as spatter droplets can lead to weld defects. These defects can include insufficient joint filling, undercutting, porosity, craters, gas inclusions, or spalling, all of which can adversely affect the mechanical properties of the weld.Typical proposed solutions for weld spatter have included reducing power, lowering the welding temperature, increasing the nozzle distance, defocusing the laser beam, changing the pulse shape, or adjusting the gas pressure to reduce the power density at the weld. However, these solutions have proven inadequate because they can limit the achievable welding speed or penetration depth and / or only partially prevent spatter formation.

[0013] Previously developed laser welding clamps also do not adequately address outgassing during welding. When the laser vaporizes the metal material and / or various impurities at the weld point, gas can be produced. Certain substances, such as aluminum alloys, outgas and can cause the undesirable formation of bubbles, pores, and cracks at the weld point during the welding process. Such formation is undesirable as it potentially impairs the quality of the weld.

[0014] It is desirable to develop a laser welding clamp that would address spatter formation at the weld point and / or take into account outgassing from the weld. It would also be desirable to provide a clamp that allows for greater flexibility in focusing the laser beam, without limiting the achievable welding speed or requiring a reduction in power density.

[0015] According to one or more embodiments, a transparent laser welding clamp is provided, comprising a body transparent to the laser wavelengths and having a laser welding section. The laser welding section includes an upper solid section and a lower hollow section. The upper solid section allows the laser wavelengths to pass through to the lower hollow section. During the laser welding process, the lower hollow section forms an interface with a sheet metal panel, captures spatter within the hollow section, and / or provides for outgassing. The embodiments disclosed herein also provide a process for laser welding with the clamp of the present disclosure.

[0016] Fig.Figure 1 represents a non-restrictive example of a laser welding clamp 10, which has a body 12 transparent to the laser wavelengths and a laser welding section 14. The body 12, which is transparent to the laser wavelengths, is made of a material that allows the operating laser wavelength(s) to pass through the laser welding section 14 to the weld point 16. The body 12 of the clamp 10, which is transparent to the laser wavelengths, can be transparent to the operating wavelengths of different lasers.

[0017] The operating wavelength of any laser depends on an active laser medium. The active laser medium is a material excited by a pump source that provides the energy for the laser system. The excited active laser medium produces spontaneous and stimulated emissions of photons, resulting in optical gain or amplification. The chemical composition of the active laser medium determines the operating wavelength of the laser. Active laser media can contain a liquid, as in dye lasers, where the chemical composition of the dye determines the operating wavelength. The liquids can be an organic chemical solvent, such as methanol, ethanol, or ethylene glycol, containing a dye, such as coumarin, rhodamine, or fluorescein. Active laser media can contain a gas, such as CO₂, Ar, Kr, and / or gas mixtures, such as He-Ne. The active laser medium can be a metal vapor, such as...Cu, HeCd, HeHg, HeSe, HeAg, or Au. The active laser media can contain solids, such as crystals and glass, typically doped with an impurity, such as Cr, Nd, Er, or Ti ions. The solid crystals can contain YAG (yttrium aluminum garnet), YLF (yttrium lithium fluoride), LiSAF (lithium strontium aluminum fluoride), or sapphire (aluminum oxide). Non-restrictive examples of doped solid active laser media include Nd:YAG, Cr:sapphire, Cr:LiSAF, Er:YLF, Nd:glass, or Er:glass. The active laser medium can contain semiconductors with a uniform dopant distribution or a material with varying dopant levels, where the movement of electrons causes the laser effect. Non-restrictive examples of active semiconductor laser media can include InGaAs, GaN, InGaN, InGaAsP.

[0018] Since the operating wavelength depends on the composition of the active laser material, the operating wavelengths of different laser types differ significantly. The terminal 10 is therefore made of a material that is transparent to the operating wavelengths of a laser used in a specific application. The laser wavelength-transparent body 12 can be transparent to one or more laser wavelengths from approximately 238 nm to approximately 10.6 µm. The laser wavelength-transparent body 12 can transmit laser wavelengths in the far ultraviolet, near ultraviolet, visible, near red, and / or far red spectrum. Table 1 below lists the operating wavelength(s) of exemplary lasers that the laser wavelength-transparent body 10 can transmit. Table 1: Example lasers and their operating wavelength(s) active laser medium Laser type Operating wavelength(s) Cr:Sapphire (Ruby) Solid 628 nm, 694 nm He:Glass Solid 1540 nm Ti:Sapphire Solid 650-1100 nm Nd:YAP Solid 1080 nm Nd:YAG Solid 1064 nm Nd:YLF Solid 1047 nm, 1053 nm Nd:Glas Solid 1060 nm Kr Gas ions 416nm, 530.9nm, 568.2nm, 647.1nm, 676.4nm, 752.5nm, 799.3nm Ar Gas ions 364nm, 457.9nm, 476.5nm, 488nm, 496.5nm, 501.7nm, 514.5nm, 1090nm CO2 gas 9,4-10,6 µm HeNe gas 543nm, 594nm, 612nm, 633nm, 1152nm N2 gas 337 nm Coumarin dye 460-515 nm Stilben dye 390-435 nm InGaAs semiconductor 980 nm Cu Metal vapor 511 nm, 578 nm

[0019] Any material transparent to the operating wavelength(s) of a laser used can be used to fabricate the laser-transparent body 12. Exemplary non-restrictive materials include various optical materials, such as borosilicate glass or borosilicate crown glass, which have a low refractive index; quartz (silicon dioxide); molten silicon dioxide (synthetic amorphous silicon dioxide); infrared-compatible calcium fluoride; magnesium fluoride; zinc selenide; various types of ceramics; or the like. The material can be amorphous or crystalline. It is desirable that the material be substantially free from various impurities, cracks, bubbles, and inclusions that could interfere with the transmission of the laser wavelengths through the clamp 10.

[0020] The material can exhibit high refractive index homogeneity of approximately 1.46 to 1.8 or higher. The refractive index refers to the rate at which light slows down as it passes through an optical material. The material can be relatively hard, as the hardness achieved during the manufacturing process can affect not only the production costs but also the durability of the optical material. The material's hardness can be approximately 6-7 or higher on the Mohs hardness scale, corresponding to 800 to 820 kgf / mm². 2 , measured according to the Knoop hardness test, or approximately 950 to 1000 kgf / mm 2or more, as measured by the Vickers hardness test. The material should have sufficient hardness so that the clamp 10 can repeatedly exert sufficient pressure on the sheet metal panels 18 to ensure proper welding. The relative hardness also affects the scratch resistance of the material. The material may exhibit good scratch resistance, good mechanical and thermal shock resistance, and / or an overall high damage threshold. The material may exhibit good resistance to cumulative exposure to radiation, particularly ultraviolet radiation. The material is thermally stable and has a relatively low coefficient of thermal expansion of about 0.54 to about 3.2 × 10⁻⁶. -6 K -1or lower, measured at 20 °C. The material can have a thermal conductivity of approximately 1 to approximately 1.46 W / mK, measured at 20 °C. In one or more embodiments, the material can exhibit good chemical resistance to various chemical substances, such as fluorine. The material can have a relatively low density to avoid making the resulting clamp 10 too heavy. An exemplary density of the material can be approximately 1 g / cm³. 3 or lower, down to about 3 g / cm² 3 or higher.

[0021] The material should exhibit excellent transmittance at the operating wavelength(s) of the laser used, such as at least 70% or more, 80% or more, 90% or more, or 95% or more. The material may have a low absorption coefficient, making it suitable for use with high-power lasers. An example absorption coefficient for the material could be approximately 0.01 cm⁻¹. -1 up to about 0.05 cm -1 , measured at 190 nm, or about 0.03 cm -1 up to about 0.07 cm -1 , measured at 2800 nm. The material can have a narrower or broader wavelength range, such as from the far ultraviolet to the far infrared spectrum, or any desired range in between.

[0022] The body 12, which is transparent to the laser wavelengths, and the laser welding section 14 can have various shapes, sizes, and configurations depending on the specific application. The cross-section of the body 12, which is transparent to the laser wavelengths, and the laser welding section 14 can be a square, a rectangle, a triangle, or the like, but is not limited to these shapes. The cross-section of the body 12, which is transparent to the laser wavelengths, and the laser welding section 14 can be angular, regular, irregular, or the like. The body 12, which is transparent to the laser wavelengths, and the laser welding section 14 can have any shape as long as the clamp 10 can transmit the laser wavelengths.

[0023] In at least one embodiment, the laser welding section 14 comprises an upper section 20 and a lower section 22. The upper section 20 can be solid. The upper section 20 allows the laser wavelength(s) to pass through to the lower section 22. When the laser beam 24 comes into contact with the clamp 10, the laser beam 24 forms an interface with the upper surface 26 of the upper section 20.

[0024] The lower section 22 contains a cavity 28 to form a lower cavity section 30. The cavity 28 is located above the weld 16. In at least one embodiment, it is possible to provide two or more welds 16 located below a cavity 28. Alternatively, the lower cavity section 30 can contain more than one cavity 28 located above more than one weld 16.

[0025] As in the Fig.As can be seen in Figures 1-5, the lower cavity section 30 can have a profile 27 along its length or a section of its length. The profile 27 defines an outline of a shape to be formed in the clamping material along the length of the lower cavity section 30. The profile 27 can have any size, shape, or configuration. The profile 27 can be semicircular, semi-oval, semi-elliptical, square, trapezoidal, triangular, rectangular, such as a parallelogram, rhombus, rhomboid, trapezoid, pentagon, hexagon, heptagon, octagon, nonagon, or decagon, or it can have more than ten sides. The profile 27 can, for example, have curved sides and can be shaped as a curved rectangle, a curved square, a curved trapezoid, or the like. The profile 27 can have rounded or sharp edges.The profile of the cavity 28 can contribute to increased flexibility in the accuracy with which the laser beam 24 must point at the weld point 16. A semicircular profile 27, which is in . Fig. Figure 1 shows a curved rectangular profile 27, which is in Fig. 2A is shown, or a trapezoidal profile 27, which is in Fig. As shown in 2B, this allows, for example, the laser beam 24 to target more than one point on the weld 16 while achieving a satisfactory quality of the resulting weld 32.

[0026] In one or more embodiments, the lower cavity section 30 can have an axial direction along its length. The lower cavity section 30, which includes the cavity 28, can extend to one or more circumferential walls 34. The cavity 28 can extend through the entire length of the clamp 10. Alternatively, the cavity 28 can extend through a section of the clamp 10. The cavity 28 extending through a section of the clamp 10 does not reach one or more circumferential walls. Such a cavity 28 can have any profile 27, as shown above. For example, the cavity 28 can be located only in a central section of the lower cavity section 30 and can have a semicircular profile 27 to form a dome that can collect splashes within the cavity 28, as shown in the Fig. 6A and Fig. 6B illustrates this.

[0027] The laser beam 24 can be a point laser beam, as in the Fig. 6A-6C shows a spot weld. Alternatively, the laser beam 24 can move along a length of the stack of sheet metal panels 18, as shown in Fig. Figure 1 shows the cavity 28 having dimensions to accommodate a width w1 of the laser beam 24 at the weld point 16. How Fig. As illustrated in Figure 2A, the cavity 28 can be as wide as the width w1 of the laser beam 24, which forms an interface with the weld 16. Alternatively, the cavity 28 can be wider than the width w1 of the laser beam 24, which forms an interface with the weld 16, as shown in Figure 2A. Fig.2B can be seen. The width w1 of the laser beam 24, which forms an interface with the weld point 16, can be calculated as the size of the focal point of the laser beam 24. The width w1 of the laser beam 24 can range from approximately several thousandths of an inch to several hundredths of an inch in diameter, from approximately 0.1 mm to approximately 0.8 mm or approximately 0.2 mm to approximately 0.4 mm.

[0028] In at least one embodiment, the cavity 28 has a width w c on, which the width w w the weld seam at weld point 16 exceeds the width w. c of the cavity 28 the width w w The width w of weld 32 at weld point 16 exceeds by approximately 1% to approximately 500% or more, by approximately 50% to approximately 250%, and by approximately 100% to approximately 175%. c The cavity 28 can be approximately 1.5 times, 2 times, 5 times, or 10 times larger than the width w. wThe weld seam 32 at the weld point 16. The width w w The weld seam 32 can be approximately 0.2-2 mm. The width w c The diameter of cavity 28 can be approximately 0.3 mm to 20 mm.

[0029] The cavity 28 has such a width w c and height h c to prevent the droplets of spatter 33 from forming insufficient joint filling, undercuts, porosity, craters, gas inclusions, or spalling at the weld point 16, and / or to provide sufficient space so that the gas from the weld point 16 can be effectively vented away from the weld seam 32. The cavity 28 can perform the dual function of preventing spatter and allowing outgassing, or only one of these functions. The shape and dimensions of the cavity 28 determine this. The domed cavity 28, which is formed in the central section of the lower cavity 30, as shown in the Fig. 6A and Fig. As shown in 6B, this can, for example, prevent splashing, while a cavity 28 extending over the entire length of the clamp 10, as shown in the Fig. As shown in 1-5, it can both prevent splashing and provide at least one degassing path.

[0030] To further promote outgassing, the lower cavity section 30 of the clamp 10 can contain one or more channels 36 extending from the lower cavity section 30 to one or more of the multiple circumferential walls 34. The one or more channels 36 provide outflow paths for the gases formed at the weld 16. The one or more channels 36 can be the only outflow paths for the gases formed at the weld 16, such as in Fig. 6C, or additional exhaust gas passages, such as in the Fig. 1-5, provide, as the gases can also escape through cavity 28.

[0031] The one or more channels 36 can have a profile along their length. The profile of the one or more channels 36 can have one of the cavity profile shapes described above. The profile of the one or more channels 36 can be substantially the same as, or different from, the profile 27 of the cavity 28. The profiles of the lower cavity section 30 and of the one or more channels 36 can be constant, but need not be. In at least one embodiment, at least one of the channels 36 can have a different profile than the remaining channels 36. Both the lower cavity section 30 and the one or more channels 36 can each have an axial direction along their length. The axial directions of the lower cavity section 30 and of the one or more channels 36 can be aligned, but need not be.In one or more embodiments, the one or more channels 36 can contain one or more interconnected channels 38. The interconnected channels 38 can be connected to various additional channels having the same or different dimensions as the interconnected channels 38. The interconnected channels 38 can form a grid. In at least one embodiment, a section of the lower cavity section 30 can contain the interconnected channels 38, while another section can contain one or more channels 36, as shown in [Figure 1]. Fig. 4 is shown. Alternatively, the entire lower cavity section 30 can contain the interconnected channels 38. Alternatively, the entire lower cavity section 30 can also contain one or more channels 36.

[0032] To provide excellent transmittance for the operating wavelength(s), it may be desirable for at least some of the clamp surfaces to have a smooth surface that is flat and free of burrs, irregularities, protrusions, breaks, or bumps. The surface may be rough and contain protrusions that can be approximately 0.1 µm to approximately 0.015 mm long. Surface roughness within this range is particularly beneficial at the interface between the laser and the top surface of the upper section 26 of the clamp 10, the inside of the cavity 28, or both. Roughness within this range provides a surface that is essentially free of protrusions and contaminants that could deflect, defocus, or absorb the laser beam.The surface quality, and consequently the roughness, of the clamp can be evaluated using a scratch-dig performance specification in accordance with MIL-PRF-13830B, which is hereby incorporated in its entirety as a reference. The scratch designation is determined by comparing the scratches on the surface to a set of standard scratches under controlled lighting conditions. The dig designation refers to a small depression in the surface and is calculated as the diameter of the depression in micrometers divided by 10. Clamp surfaces should therefore exhibit scratch-dig specifications of approximately 80-50, considered standard quality; approximately 60-40, considered precision quality; or approximately 20-10, considered high-precision quality.

[0033] Because all metals reflect light to some degree, especially metals such as gold, silver, copper, and aluminum, the sheet metal sheets 18 can be difficult to weld, requiring intense energy typically available from high-energy peak pulses. Choosing a laser with a shorter operating wavelength, such as the 1.06 µm wavelength of the Nd:YAG laser, which is more readily absorbed than the longer operating wavelengths, such as the 10.6 µm wavelength of the CO2 laser, makes certain lasers more suitable for welding highly reflective sheet metal sheets 18. Additionally, a light-absorbing material, such as graphite, can be applied to the weld joint 32 to reduce the reflectivity of the sheet metal sheets 18. The light-absorbing material can be applied as a coating.The light-absorbing coating is selected according to the operating wavelength of the laser used. Examples of absorbing materials can have peak wavelengths anywhere within the ultraviolet, visible, or infrared spectra.

[0034] Alternatively, in one or more embodiments it may be desirable to provide a low-absorbing, low-refractive and / or anti-reflective layer or layers 40 on at least one surface of the clamp 10, or to manufacture at least some sections of the clamp 10, such as the upper section 20, the lower section 22, the laser-welded section 14 or a combination thereof, from a material having low-absorbing, low-refractive and / or anti-reflective properties in order to achieve excellent transmittance, such as above about 90%. Fig.Figure 2B illustrates an anti-reflective material layer 40 that is in contact with the surface of the upper solid section 20 of the laser welding section 14. Fig. Figure 3, on the other hand, illustrates the body 12, which is transparent to the laser wavelengths and contains a low-absorbing material 40. The low-absorbing material can be approximately 0–50% absorbent. The type of material from which the laser-welded section 14 is made determines the need for low-absorbing, low-refractive-index, and / or anti-reflective coatings. Materials with a low refractive index, such as magnesium fluoride, may not require an anti-reflective coating. Conversely, materials with a high refractive index, such as zinc selenide, may require an anti-reflective coating to achieve high transmittance. Exemplary anti-reflective coatings can contain materials with a reflection coefficient R aveexhibiting deviations of less than 0.25 to 1.5% at the operating wavelengths of the laser welding section 14.

[0035] As explained above, the clamp 10 is sufficiently rigid to provide adequate clamping pressure on the sheet metal plates 18. Sufficient pressure is developed if the sheet metal plates 18 are aligned and pressed to remain aligned, thus creating a substantially gap-free connection at the weld point 16. The clamping force is sufficient if the sheet metal plates 18 remain aligned throughout the welding process. The absence of close contact between the sheet metal plates 18 during the welding operation can reduce the overall conductive weld area, which is particularly disadvantageous in some applications. Such applications include those requiring charging at approximately 500 A for about 10 s without generating a local transient thermal event, such as DC fast charging in high-voltage batteries.The stack of sheet metal panels 18 is essentially gap-free, provided that no gaps larger than approximately 50 µm appear between the stacked laser-welded panels. Gaps larger than approximately 50 µm can lead to reduced mechanical properties of the weld 32 and impaired weld quality along the length of the weld 32 for the intended purpose.

[0036] The sheet metal panels 18 can be positioned between the clamp 10 and a base plate 42. The base plate 42 can be made of various materials, such as the materials disclosed for the sheet metal panels 18 themselves, which are referenced below. The base plate 42 can be made of a material that requires a higher melting temperature than the sheet metal panels 18. The base plate 42 must be sufficiently hard and temperature-resistant to withstand the laser welding process without disintegrating. It is desirable that the base plate 42 does not deform. The base plate 42 can be attached to a clamping device to prevent its displacement and, consequently, to prevent misalignment of the sheet metal panels 18 during the welding process.

[0037] The sheet metal panels 18 to be joined by laser welding can have various dimensions. For example, sheet metal panels 18 can have a thickness of less than approximately 0.2 mm to more than approximately 0.8 mm. The sheet metal panels 18 can be a sheet. The clamp 10 can be used to join one or more sheet metal panels 18 of the same thickness, as shown in the Fig. 1 and Fig. 2A can be seen, or of different thicknesses, as in the Fig. 2B and Fig. Figure 3 illustrates how to connect them. Terminal 10 can also be used for micro-welding of the microelectronics. The sheet metal panels 18 can therefore have micro-scale dimensions.

[0038] The material of the sheet metal panels 18 can vary depending on a specific application. An example of a material for one or more of the sheet metal panels 18 includes, but is not limited to, aluminum, silver, gold, copper, tin, nickel, titanium, steel (such as stainless steel), or the like, or their alloys. While the panels 18 are referred to as sheet metal panels 18, it is noted that the clamp 10 can be used during laser welding of panels that include other materials, such as thermoplastics.

[0039] The terminal 10 and the related method of the present disclosure can be used to connect the sheets 18 in various applications, such as medical devices, biotechnology, electronics, motor vehicles, aerospace, and alternative energy / photovoltaics. An exemplary use of the terminal 10 is welding a high-voltage battery from solder lug to solder lug and from solder lug to busbar. A non-limiting exemplary use of the terminal 10 is laser welding the electrical connections in a high-voltage battery for battery-powered vehicles. It is considered that the stacks of the sheet metal sheets 18, which contain a number of sheets 18 with a thickness of less than 0.2 mm, would be laser welded while using the terminal 10 of the present disclosure.The resulting laser-welded cell solder tab can replace the ultrasonically welded battery stacks. While the method of the present disclosure may require relatively high upfront costs compared to ultrasonic welding, the present method can lead to lower unit costs due to the faster and highly repeatable positioning of the laser beam and the lower maintenance costs compared to ultrasonic welding. Terminal 10 and the related method of its use can also be employed in fuel cell applications, such as welding the metal spacers for the fuel cells. Such an application may require welding in narrow valleys in areas approximately 0.15 mm wide.

[0040] The present disclosure further provides a method for laser welding a number of sheet metal panels 18 by clamping the sheet metal panels 18 together with a clamp 10, which has a body 14 transparent to the laser wavelengths and a cavity 28. The clamping step can include arranging a number of sheet metal panels 18 between the clamp 10 and one or more base plates 42. The process further includes a step of transmitting laser light through the body 14, which is transparent to the laser wavelengths, and the cavity 28 onto the sheet metal panels 18 to form a weld 32 at a weld point 16 of the sheet metal panels 18. The transmitting step forms molten metal splashes 33 from the number of sheet metal panels 18. The process includes a step of collecting the molten metal splashes 33 within the cavity 28. The transmitting step further generates a gas within the cavity 28.The method further provides a step of degassing the gas from the cavity 28. The degassing step can include the degassing of the gas from the cavity 28 through one or more channels 36 or one or more interconnected channels 38.

[0041] The procedure may further include the formation of battery solder tabs and / or battery busbars while using terminal 10. Fig. 5A and Fig. 5B illustrates the formation of battery solder tabs by overlapping sheets of metal. 18. Fig. Figure 5A shows the overlapping of the opposite ends of two sheet metal panels 18, which are to be welded together. Fig. Figure 5B illustrates the overlapping on the same side of two sheet metal panels 18 that are to be welded together.

[0042] While exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms of the disclosure. Instead, the words used in the description are descriptive rather than limiting, and it is understood that various modifications can be made without deviating from the inventive concept and scope of protection of the disclosure. Furthermore, the features of the different implementing embodiments can be combined to form further embodiments of the disclosure.

[0043] It is further described as follows: A. Sheet metal laser welding clamp, which includes the following: a body transparent to the laser wavelengths, which has a laser welding section, wherein The laser welding section includes an upper solid section for passing the laser wavelengths to a lower cavity section for forming an interface with a sheet metal panel during a laser welding operation. B. Sheet metal laser welding clamp according to A, wherein the lower cavity section has an axial direction along its length. C. Sheet metal laser welding clamp according to A, wherein the lower cavity section has a profile along its length. D. Sheet metal laser welding clamp according to C, wherein the profile of the lower cavity section is constant along the length of the profile of the lower cavity section. E. Sheet metal laser welding clamp according to C, wherein the profile of the lower cavity section is a substantially semicircular profile. F. Sheet metal laser welding clamp according to C, wherein the profile of the lower cavity section is a trapezoidal profile. G. Sheet metal laser welding clamp according to A, wherein the lower cavity section and / or the upper solid section has a surface containing several protrusions with a length in a range of about 0.1 µm to about 0.015 mm. H. Sheet metal laser welding clamp, which further comprises an anti-reflective material that is in contact with a surface of the upper solid section of the laser welding section. I. Sheet metal laser welding clamp according to A, wherein the laser welding section contains a low absorbing material. J. Sheet metal laser welding clamp, which includes the following: a body transparent to the laser wavelengths, comprising a laser welding section and multiple circumferential walls, wherein the laser welding section includes an upper solid section for allowing the laser wavelengths to pass through to a lower cavity section for forming an interface with a sheet metal panel during a laser welding operation, and one or more channels extending from the lower cavity section to one or more of the multiple circumferential walls. K. Sheet metal laser welding clamp according to J, wherein the lower cavity section and the one or more channels each have a profile along its length. L. Sheet metal laser welding clamp according to K, wherein the profiles of the lower cavity section and of the one or more channels are constant. M. Sheet metal laser welding clamp according to J, wherein the lower cavity section and the one and the multiple channels each have an axial direction along its length. N. Sheet metal laser welding clamp according to M, wherein the axial directions of the lower cavity section and of the one or more channels are aligned. O. Sheet metal laser welding clamp according to J, wherein the one or more channels contain one or more interconnected channels. P. Method for laser welding multiple sheet metal panels, comprising: pressing the multiple sheet metal panels together with a clamp having a transparent body and a cavity; and passing the laser light through the transparent body and the cavity onto the multiple sheet metal panels to form a weld seam at a welding point of the multiple sheet metal panels. Q. Method according to P, wherein the transparent body is a body transparent to the laser wavelengths. R. Method according to P, wherein the step of passing liquid metal splashes from the several sheet metal panels comprises collecting the liquid metal splashes within the cavity. S. Method according to P, wherein the step of letting through generates a gas inside the cavity and further comprises the outgassing of the gas from the cavity. T. Method according to S, wherein the outgassing step includes the outgassing of the gas from the cavity through one or more channels.

Claims

[1] Molded body (12) for a sheet metal laser welding clamp (10) which is transparent to the laser wavelengths and has a laser welding section (14) wherein the laser welding section (14) includes an upper solid section (20) for transmitting the laser wavelengths to a lower cavity section (22) for forming an interface with a sheet metal panel (18) during a laser welding operation, and the material of the molded body (12) has a coefficient of thermal expansion of 0.54 to 3.2·10 -6 K -1 , measured at 20 °C. [2] Molded body (12) according to claim 1, wherein the lower cavity section (22) has a profile (27) along its length which is constant along the length. [3] Molded body (12) according to claim 2, wherein the profile (27) of the lower cavity section (22) is a semicircular profile (27). [4] Molded body (12) according to claim 2, wherein the profile (27) of the lower cavity section (22) is a trapezoidal profile (27). [5] Molded body (12) according to claim 1, wherein the sheet metal laser welding clamp (10) further comprises an antireflection material which is in contact with a surface of the upper solid section (20) of the laser welding section (14), wherein the antireflection material has a reflection coefficient R ave exhibits less than 0.25 to 1.5% at the operating wavelengths of the laser welding section (14). [6] Molded body (12) according to claim 1, wherein the laser welding section (14) contains a low absorbing material which is less than 50% absorbing. [7] Molded body (12) for a sheet-plate laser welding clamp (10), which is transparent to the laser wavelengths and has a laser welding section (14) and several circumferential walls (34), wherein the laser welding section (14) includes an upper solid section (20) for transmitting the laser wavelengths to a lower cavity section (22) for forming an interface with a sheet metal panel (18) during a laser welding operation, and one or more channels (36) extend from the lower cavity section (22) to one or more circumferential walls (34) located on a lateral part of the molded body (12) and are configured to abut the sheet metal panel (18). [8] Molded body (12) according to claim 7, wherein the lower cavity section (22) and the one or more channels (36) each have a profile (27) along its length, the profiles (27) being constant along the length. [9] Molded body (12) according to claim 7, wherein the cavity section (22) and the one or more channels (36) each have an axial direction along its length. [10] Molded body (12) according to claim 9, wherein the axial directions of the lower cavity section (22) and of the one or more channels (36) are aligned. [11] Molded body (12) according to claim 7, wherein the one or more channels (36) contain one or more interconnected channels. [12] Method for laser welding multiple sheet metal panels (18) comprising the following: Pressing together several sheet metal panels (18) with a sheet metal laser welding clamp (10) which has a shaped body (12) and a cavity (28), and Passing the laser light through the molded body (12) and the cavity (28) onto the multiple sheet metal panels (18) to form a weld seam (32) at a weld point (16) of the multiple sheet metal panels (18), wherein the shaped body (12) is a body transparent to the laser wavelengths. [13] Method according to claim 12, wherein the step of passing liquid metal splinters from the multiple sheet metal panels (18) and further includes collecting the liquid metal splashes within the cavity (28). [14] Method according to claim 12, wherein the step of letting through generates a gas inside the cavity (28) and further includes the outgassing of the gas from the cavity (28). [15] Method according to claim 14, wherein the outgassing step includes outgassing the gas from the cavity (28) through one or more channels (36).

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