DE102022210061A1 - Device and method for laser beam welding of components - Google Patents

Abstract

The invention relates to a device and a method for laser beam welding of a first component (6) with a second component (5), in which a first laser beam device (1a) directs a welding laser beam (2) onto the outer surface (4) of the first component (5). in order to weld the first component (5) along a weld seam (8) to be formed with the second component (6) brought into contact therewith by forming a melt pool (7) across the component, the first laser beam device (1a) being used to generate the welding laser beam ( 2) at least one second laser beam device (1b) is assigned for generating a secondary laser beam (3), the secondary laser beam (3) extending at an acute angle (α) to the welding laser beam (2) onto an edge region (9) of the welding laser beam (2) The melt pool (7) produced in the first component (5) is aligned, so that an edge-side melt pool expansion (10) is formed.

Description

The invention relates to a device and a method for laser beam welding, in particular laser beam deep welding, of a first component with a second component, in which a laser beam device directs a welding laser beam onto the outer surface of the first component in order to abut the first component along a weld seam to be formed brought to weld the second component by forming a cross-component melt pool.

The field of application of the invention extends to cohesive connections, which are to be produced primarily for large-format, flat components of all kinds, in particular metal sheets or metal foils. Laser deep beam welding, which is of interest here, can be used not only on metal components but also on plastic components with appropriate adjustment of the process parameters.

State of the art

From the DE 10 2021 113 430 A1 discloses a method for laser beam deep welding of two flat components, in which a laser beam device generates a vertical laser beam with a deep welding laser beam component, which is moved at a feed speed along a weld seam to be formed, the deep welding laser beam component generating a vapor capillary in the material, which is formed by a Molten pool is surrounded and which moves with the laser beam in the welding direction through the material of the components. The first component is welded through and the laser beam only partially penetrates the second component underneath in order to melt it only over a portion of its thickness. A flow around the capillary is formed, in which a metal melt located on the capillary front flows through melt pool channels formed on both sides of the steam capillary towards the back of the capillary and solidifies there.

During laser beam welding of the type of interest here, melt drops can be detached from the highly dynamic melt pool, which can be deposited as weld spatter on the outer surface of the upper component and adhere to it. These usually have to be removed mechanically or otherwise after the welding process in order to obtain the smoothest possible external surface. In extreme cases, such a detachment of melt drops even requires the steam capillary to be refilled with melt flowing back in order to ensure a sufficiently stable weld seam. This can only be monitored and implemented with considerable effort in terms of control technology.

According to the generally known state of the art, the so-called secondary nozzle process is already used to avoid spatter during laser beam welding. Here, a gas flow that is opposite to the welding laser beam is directed onto the melt pool, which is generated by a secondary nozzle and, as a result of the transfer of the flow impulse to the melt pool, leads to capillary expansion. However, the process parameters of the gas stream and its focusing can only be set with great effort and within narrow effectiveness limits.

It is therefore the object of the present invention to further improve a device and a method for laser beam welding of the type described above in such a way that detachment of melt drops from the melt pool is avoided or at least reduced with little technical effort.

Disclosure of the invention

The invention includes the technical teaching that a conventional welding laser beam for laser beam welding is combined with at least one secondary laser beam in such a way that the secondary laser beam, running at an acute angle α to the welding laser beam, is directed at an edge region of the melt pool generated by the welding laser beam in the first component in order to be directed at this To create an expansion of the melt pool at the edge. The term melt pool expansion also includes an associated capillary expansion in the melt pool, which occurs around the laser beam. The edge region of the melt pool is also understood to be the boundary formed on the outer surface of the first component during welding between the solid material and the liquid melt pool.

The advantage of the solution according to the invention is, in particular, that the melt pool expansion achieves a spatter-reducing capillary expansion of the melt pool usually generated by the welding laser beam. Since the secondary laser beam provided for this purpose is freely scalable via the laser beam device with regard to its process parameters, such as wavelength and spot diameter, the effectiveness in terms of minimal spatter emission can be flexibly adjusted, even with different materials.

Preferably, an electronic control unit is provided for synchronously controlling the first laser beam device and the second laser beam device in such a way that the secondary laser beam is aligned at the above-specified acute angle α to the welding laser beam. The control unit preferably ensures simultaneous output of the welding laser beam and the secondary laser beam. The two laser beam devices can be combined to form a common structural unit.

According to a preferred embodiment of the invention, the secondary laser beam is aligned opposite to the feed direction of the welding laser beam at the acute angle α crossing the welding laser beam. As a result, the secondary laser beam is aimed at the rear part of the melt pool, which solidifies piece by piece due to the feed movement to form the weld seam. In other words, with this special arrangement, an optical pressure is generated on the capillary back wall by the secondary laser beam. This results in a seam modification, which is visible in the solidified weld seam and ensures a higher material connection between the upper and lower component. Thanks to the steam capillary expanded according to the invention, faster welding is also possible with a higher feed rate compared to conventional laser beam welding, without this increasing spatter formation.

According to a preferred embodiment, the melt pool expansion generated by the secondary laser beam extends over a smaller area Q than the melt pool generated by the welding laser beam. As a result, the conventional welding laser beam has a higher share in the creation of the weld seam to be formed than the secondary laser beam, which primarily serves to expand the capillary and thus reduce spatter.

For laser beam welding, the welding laser beam preferably consists of a melting laser beam component to generate the melt pool width B and a deep welding laser beam component surrounded by it to generate the melt pool depth T.

With regard to the process parameters for the laser beam device, a stable weld seam can be achieved while avoiding spatter by selecting a material-specific wavelength of the welding laser beam in the range between 343 nanometers (nm) to 10,600 nm. The wavelength of the welding laser beam is preferably 400 nm to 1070 nm. This preferred range, which was determined through tests, is based in particular on the relatively high absorption coefficients for technically relevant metals, for example iron-based, copper, aluminum or titanium alloys, and therefore depends on the material as is known .

With regard to the secondary laser beam, the same process parameters can be selected in the preferred ranges, since the degree of capillary expansion is also directly related to the absorption coefficients of metals. However, it is also possible to choose different wavelengths for the welding laser beam and the secondary laser beam within the specified range, provided that melting of the material is ensured.

The welding laser beam and the additional laser beam assigned to it in a movement-coordinated manner can be operated with a synchronous feed speed V in the range between 1 meter per minute (m/min) to 120 m/min. With regard to the lower range limit, particularly small feeds can be achieved in order to reliably connect large material thicknesses with little spatter. These advantages of the solution according to the invention can be maintained, especially with relatively thinner components, up to a feed speed of 120 m/min. This means that particularly fast feed speeds can be achieved, which make it possible to produce particularly long weld seams on large-area components within a short processing time.

With regard to the spot diameter of the welding laser beam and the secondary laser beam on the outer surface of the upper component, diameter values between 15 µm and 1200 µm can be selected. This makes it possible to create particularly fine weld seams, particularly in thin components, whereas the solution according to the invention also makes it possible to form particularly thick weld seams in correspondingly thick components. A spot diameter between 50 and 200 µm is preferably suggested. This is particularly advantageous for applications in which relatively thin components (in the tenth of a mm range) need to be connected to one another quickly and reliably, i.e. with sufficient connection in a possibly corrosive environment.

However, it is also possible to choose different spot diameters for the welding laser beam and the secondary laser beam within the specified range, for example a smaller spot diameter for the secondary laser beam compared to the welding laser beam, in order to achieve only a slight expansion of the melt pool.

In the context of the present invention, a lower component is preferably welded to an upper component, for example metal sheets or metal foils, in particular via an overlap joint. However, it is also conceivable to have several stacked on top of each other or even Round components as well as components lying next to each other on the same level can also be connected to the solution according to the invention using a butt joint.

Detailed description based on drawing

• 1 eine schematische Seitenansicht einer Vorrichtung zum Laserstrahlschweißen eines ersten Bauteils mit einem zweiten Bauteil, und
• 2 ein Flussdiagramm zur Veranschaulichung der Verfahrensschritte zur Durchführung des erfindungsgemäßen Laserstrahlschweißens.

Further measures improving the invention are shown in more detail below together with the description of a preferred exemplary embodiment of the invention with reference to the figures. It shows:

• 1 a schematic side view of a device for laser beam welding of a first component with a second component, and
• 2 a flowchart to illustrate the process steps for carrying out laser beam welding according to the invention.

According to 1 A device for laser beam welding comprises a first laser beam device 1a, which generates a substantially vertical welding laser beam 2, and an adjacent second laser beam device 1b for generating a secondary laser beam 3 positioned at an acute angle α thereto. The welding laser beam 2 and the secondary laser beam 3 are on an outer surface 4 first upper flat component 5 directed. A second lower flat component 6 is arranged under the first upper flat component 5 and fixed in the desired position. In this exemplary embodiment, the first component 5 and the second component 6 to be cohesively connected to it consist of a steel sheet of the same material.

The welding laser beam 2 generated by the laser beam device 1a is set in terms of its process parameters in such a way that the first component 5 is completely welded through and the second component 6 is melted by forming a cross-component melt pool 7, so that after the melt pool 7 has solidified, the welding laser beam is in the rear area 2 - i.e. against the feed direction - forms a weld seam 8 for the desired cohesive component connection.

The welding laser beam 2 is combined with the secondary laser beam 3 generated by the laser beam device 1b in such a way that the secondary laser beam 3, running at an acute angle α to the welding laser beam 2, aims at a rear edge region 9 of the melt pool 7 generated by the welding laser beam 2 in the upper component in order to create a welding pool 7 at this point to create edge-side melt pool expansion 10. The secondary laser beam 3 is aligned opposite to the feed direction V of the welding laser beam 2 and crossing the welding laser beam 2 at the acute angle α. Since the secondary laser beam 3 of the laser beam device 1b is connected to the laser beam device 1a for the welding laser beam 2 to form a structural unit, the welding laser beam 2 and secondary laser beam 3 move at the same feed speed in the feed direction V shown. The melt pool expansion 10 obviously extends over a smaller area Q than that Melt pool 7 generated by the welding laser beam 2.

The dashed line between the first laser beam device 1a and the second laser beam device 1a indicates that both laser beam units 1a and 1b can optionally also be designed separately. In any case, both laser beam units 1a and 1b are controlled synchronously by an electronic control unit 100, with which they are therefore in communicative connection.

For laser beam welding, the welding laser beam 2 consists of a melting laser beam portion 11 of larger diameter, which essentially produces the melt pool width B. This includes a deep welding laser beam portion 12 of the welding laser beam 2, which is used to generate the melt pool depth T and the vapor capillary.

According to 2 the method for laser beam welding of the two components 5 and 6 using the device described above is based on providing the two components 5 and 6 arranged one above the other. The vertical welding laser beam 2 is then generated by the first laser beam device 1a as part of a process step B and immediately afterwards or simultaneously by means of the second laser beam device 1b the secondary laser beam 3 aimed at the edge region of the melt pool is generated as part of the process step C. By moving the two laser beam devices 1a and 1b in the feed direction V, the two components 5 and 6 are finally welded with little spatter.

The invention is not limited to the preferred embodiment described above. Rather, modifications of this are also conceivable, which are included within the scope of protection of the following claims. For example, it is possible to weld components of different types of the same material, for example plastic components. For this purpose, the welding parameters, such as in particular the wavelength, spot diameter and feed speed of the welding laser beam and the secondary laser beam, must be adapted to the material and geometry. In addition, it is not absolutely necessary that the welding laser beam is aligned orthogonally. It is conceivable that this itself falls on the component at an acute angle. Important is maintaining the acute angle between the welding laser beam and the secondary laser beam. It is also conceivable, for example, to operate the welding laser beam at an angle of incidence of 20° and the secondary laser beam at 50°, so that an angle of 30° is established between the two beams.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102021113430 A1 [0003]

Claims (11)

Device for laser beam welding of a first component (6) with a second component (5), in which a first laser beam device (1a) directs a welding laser beam (2) onto the outer surface (4) of the first component (5) in order to move along a weld seam to be formed (8) to weld the first component (5) with the second component (6) brought into contact therewith by forming a melt pool (7) across the components, characterized in that the first laser beam device (1a) for generating the welding laser beam (2) has at least one second laser beam device (1b) is assigned for generating a secondary laser beam (3), the secondary laser beam (3) extending at an acute angle (α) to the welding laser beam (2) onto an edge region (9) of the welding laser beam (2) in the first component ( 5) generated melt pool (7) is aligned, so that an edge-side melt pool expansion (10) is formed. Device according to Claim 1 , characterized in that an electronic control unit (100) is provided for synchronously controlling the first laser beam device (1a) and the second laser beam device (1b). Device according to Claim 1 , characterized in that the secondary laser beam (3) of the second laser beam device (1b) is aligned counter to the feed direction (V) of the welding laser beam (2) and crossing the welding laser beam (2) at the acute angle (α). Device according to Claim 1 , characterized in that the melt pool expansion (10) generated by the secondary laser beam (3) of the second laser beam device (1b) extends over a smaller area (Q) than the melt pool (7) generated by the welding laser beam (2). Device according to Claim 1 , characterized in that the welding laser beam (2) of the first laser beam device (1a) consists of a melting laser beam component (11) for generating the melt pool width (B) and a deep welding laser beam component (12) surrounded thereby for generating the melt pool depth (T). Method for laser beam welding a first component (6) to a second component (5) with a device according to one of the preceding claims, in which a welding laser beam (2) is directed onto the outer surface (4) of the first component (5) by a first laser beam device (1a), so that the first component (5) is welded to the second component (6) brought into contact therewith along a weld seam (8) to be formed by forming a melt pool (7) across the components, characterized in that the first laser beam device (1a) for generating the welding laser beam (2) is combined with at least one second laser beam device (1b) for generating a secondary laser beam (3) in such a way that the secondary laser beam (3) is directed at an acute angle (α) to the welding laser beam (2) onto an edge region (9) of the melt pool (7) generated by the welding laser beam (2) in the first component (5) in order to form a melt pool widening (10) on the edge. Procedure according to Claim 6 , characterized in that the welding laser beam (2) is generated with a material-specific wavelength in the range between 343 nm to 10,600 nm, preferably 400 nm to 1070 nm. Procedure according to Claim 6 , characterized in that the secondary laser beam (3) is generated with a material-specific wavelength in the range between 343 nm to 10,600 nm, preferably 400 nm to 1070 nm. Procedure according to Claim 6 , characterized in that the welding laser beam (2) and the associated secondary laser beam (3) are moved at a feed speed (V) in the range between 1 m/min to 120 m/min. Procedure according to Claim 6 , characterized in that the spot diameter of the welding laser beam (2) and the secondary laser beam (3) on the outer surface (4) of the upper component (5) is in the range between 15 µm to 600 µm, preferably 50 µm to 200 µm. Component arrangement, comprising at least a first component (6) and at least a second component (5), which are produced by a method according to one of the above Claims 6 until 10 are materially connected to each other by laser beam welding.

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