Installation and process of laser welding for the mutual joining of two metal parts

Abstract

Installation and method for laser welding for the mutual assembly of two metal parts The invention relates to an installation (1) for laser welding for the mutual assembly, face to face, of two metal parts (2 and 3) in the form of flat plates, comprising a support structure (4) with a receiving surface (5) for the two plates (2 and 3) to be assembled and at least one laser welding head (6) that can be moved relative to said receiving surface (5) and above said first upper plate (2).An installation characterized in that it comprises at least one peripheral airtight sealing means (8), configured to achieve a seal between the first upper plate (2) and the receiving surface (5), and in that the support structure (4) incorporates an air intake means (9) or vacuum generator, which is in fluidic communication with the receiving surface (5) and the peripheral lateral linear opening (10) of the interstitial plane (PI) between the two superimposed plates (2 and 3). Figure to be published with the abbreviation: Fig. 2.

Description

Title of the invention: Laser welding installation and method for the mutual joining of two metal parts

[0001] The present invention relates to the field of industrial processes and equipment for the assembly of parts by welding, more particularly the joining by welding using a laser beam of two metal plates or panels, and aims at an installation and a laser welding process for the mutual assembly of two metal parts.

[0002] Usually, the clamping (holding in position) of parts to be assembled together during a welding process is carried out by mechanical locking (manual or motorized / automated) or holding by magnetic attraction.

[0003] The nature and design of the clamping means depend in particular on the shape of the parts to be assembled, the type of weld bead, the welding sequence or similar parameters, and must allow for the management of expansions and warping between parts inherent in welding processes, in particular fusion welding.

[0004] An acceptable compromise must be found between the need for sufficient blocking of the parts (generating potentially damaging residual stresses in the welds) and the need for certain degrees of freedom (allowing undesired deformations in the assembled composite part).

[0005] In addition to the two most common types of clamping mentioned above, vacuum clamping implementations are also known, which also improve the quality of the weld (the elimination of air in contact with the weld pool greatly reduces the concentration of oxygen and hydrogen and leads to a decrease in the porosity rate and a stabilization of the "keyhole" produced by the laser beam at the point of impact).In the prior art, for example, in relation to this vacuum clamping technique, a welding installation with a workpiece holding device and a laser welding device, both housed in a hermetically sealed enclosure, is known (see, for example, DE 102019000291); a laser welding installation is also known in which the workpiece holding device is housed in a vacuum enclosure, closed by a wall with a transparent window through which the focused laser beam can pass, thus limiting its access to the parts to be welded (see, for example, CN108637470).

[0006] However, although this clamping technique makes it possible to find a good compromise between the two aforementioned antagonistic needs, the installations implemented are complex, bulky, costly and unsuitable for large flat parts, such as plates.

[0007] The main purpose of the present invention is to overcome the various disadvantages mentioned above, while retaining all the other advantages of vacuum clamping.

[0008] To this end, the invention relates to a laser welding installation for the mutual assembly, face to face, of two metal parts in the form of flat plates, said installation comprising a support structure with a receiving surface for the two plates to be assembled, arranged in a superimposed manner and of which at least one first upper plate has a continuous constitution, and at least one laser welding head that can be moved, in particular automatically by a robotic device and under the control of a control unit, relative to said receiving surface and above said first upper plate of the arrangement of two superimposed plates, preferably in a plane parallel to said receiving surface and advantageously in accordance with a pre-programmed movement path,

[0009] installation characterized in that it includes at least one peripheral air sealing means, configured to achieve a seal between the first upper plate and the receiving surface and in that the support structure integrates, or is connected to, an air suction means or vacuum generator, which is in fluidic communication with the receiving surface and the peripheral lateral linear opening of the interstitial plane between the two superimposed plates.

[0010] The invention will be better understood from the following description, which relates to preferred embodiments, given by way of non-limiting examples, and explained with reference to the accompanying schematic drawings, in which:

[0011] [Fig-1] is a schematic top view of a laser welding assembly installation according to the invention, with a welding head;

[0012] , [Fig.2], [Fig.3] and [Fig.4] are schematic cross-sectional representations according to AA of the installation shown [Fig.1], illustrating three variants of the invention;

[0013] [Fig.5] is a top and perspective view of an embodiment of a plate basic with its network of grooves at the level of the bearing surface, which can be part of an installation as shown in any one of figures 2 to 4.

[0014] Figures 1 to 4 schematically illustrate several variants of the embodiment of a laser welding installation (1) for the mutual assembly, face to face, of two metal parts (2 and 3) in the form of flat plates.

[0015] This installation (1) comprises a support structure (4) with a receiving surface (5) for the two plates (2 and 3) to be assembled, which are arranged in a superimposed manner on this surface for the purpose of their assembly and of which at least one first upper plate (2) has a continuous constitution, and at less a laser welding head (6) which can be moved, in particular automatically by a robotic device (7) and under the control of a control unit (7'), relative to said receiving surface (5) and above said first upper plate (2) of the arrangement of two superimposed plates (2 and 3), preferably in a plane (PP) parallel to said receiving surface (5) and advantageously in accordance with a preprogrammed movement route.

[0016] According to the invention, this installation (1) also includes at least one peripheral air sealing means (8), configured to achieve a seal between the first upper plate (2) and the receiving surface (5) and the support structure (4) incorporates, or is connected to, an air suction means (9) or vacuum generator, which is in fluidic communication with the receiving surface (5) and the peripheral lateral linear opening (10) of the interstitial plane (PI) between the two superimposed plates (2 and 3).

[0017] Thanks to the inventive provisions above, a relative vacuum chamber is provided, ensuring forced application of the two plates (2 and 3) of the superimposed arrangement against each other and locking said arrangement in position on the receiving surface (5). Given the configuration of the installation (1), access from above to the first upper plate (2) is completely unobstructed, possibly with the exception of a thin peripheral strip (see Figures 3 and 4) not involved in the assembly operation. Furthermore, since the vacuum is applied from below and laterally to the two plates to be assembled, and no means related to the vacuum clamping are located in the volume above the upper plate (2), there is no risk of interference with or limitation of movement related to said at least one laser welding head (6). Finally, the overall footprint of the installation (1) is limited.

[0018] The variants of the installation (1) shown comprise only a single welding head (6) emitting a focused laser beam (FLC), but of course the invention also relates to an installation (1) with at least two heads whose movements are coordinated with each other. This installation may, for example, comprise a moving head (or scanning head) and / or a fixed head moved by a suitable device.

[0019] It should be noted that the weld line or each weld line produced by the action of the laser welding head(s) (6) can be continuous or segmented.

[0020] The second lower plate (3) is preferably also structurally continuous, and the two plates advantageously have rectangular shapes, of the same size or not (upper plate larger). However, it may also have openings (obviously outside the weld lines) and in this case the relative vacuum (for example less than 0.05 atmospheres) generates an additional pinching of this second plate (3) between the first upper plate (2) and the receiving surface (5), in addition to the pressurized contact of the two plates (2 and 3) under the effect of the partial vacuum between them produced by the suction at the level of the peripheral lateral linear opening (10), or slot opening to the outside, of the interstitial plane (PI) between the two superimposed plates (2 and 3).

[0021] Advantageously, the support structure (4) comprises a base plate (4') having the receiving surface (5) and connected to the means (9) of air suction or vacuum generator by at least one fluidic connection line (11) opening at the level of said receiving surface (5), under the second lower plate (3) of the arrangement of two superimposed plates (2 and 3) and / or beyond the lateral edge (3') of this second lower plate (3), when such an arrangement rests on the base plate (4').

[0022] This or each connection line (11) may be at least partially formed or recessed into the base plate (4') (see Figures 2 to 4), namely at least for its terminal portion. In the case of multiple connection lines (11), each may have a through-opening outlet (11', 11"). The means (9) may be mounted on the support structure (4) or separate from it (it may optionally be a suction outlet from a network extending across the site receiving the installation (1), connected to the base plate (4) by a conduit).

[0023] Depending on the configuration of the base plate (4') and the relative dimensions of the first and second plates of the arrangement, the seal can be achieved either directly between the first upper plate (2) and the receiving surface (5) by means of a single sealing means (8), as shown in Figures 2 and 3, or with the interposition of a support and holding frame (14) and the implementation of two sealing means (8, 8') interposed respectively between the first plate and said frame, for one (8), and said frame and the receiving surface, for the other (8'), as shown in [Fig.4].

[0024] In accordance with an alternative embodiment, shown in [Fig. 5] and ensuring effective vacuuming, the receiving surface (5) has a plurality of through openings (11', 11") fluidly connected by means (9) of air suction or vacuum generator, by at least one connecting line (11), and distributed on this surface (5) homogeneously or according to a predefined pattern, at least one (11') of said openings (11', 11") being located beyond the lateral edge (3') of the second lower plate (3), when an arrangement of superimposed plates (2 and 3) is arranged on the receiving surface (5), and within the perimeter delimited by said at least one sealing means (8).

[0025] As shown in [Fig. 5] and Figures 2 to 4 by way of example, and in order to achieve a substantially homogeneous distribution of the relative vacuum suction effect, the receiving surface (5) has a network of channels (12), mutually interconnected and arranged according to a determined pattern. This network (12) is fluidly connected by means of (9) air suction or vacuum generator by at least one connecting line (11), opening into said channel network (12) by at least one opening (11') located beyond the lateral edge (3') of the second lower plate (3) and / or by at least one opening (11”) opening below the second lower plate (3), when an arrangement of superimposed plates (2 and 3) is disposed on the receiving surface (5).

[0026] Preferably, the channel network (12), for example grooves formed in the surface of the base plate (4'), and the location scheme of the weld line(s) are determined correlatively so as to avoid any crossing between a channel and a line.

[0027] In accordance with a very favorable constructive variant of the invention, shown in Figures 2 and 3 and facilitating the obtaining of a hermetically sealed enclosure between the first plate (2) and the receiving surface (5), the latter is provided peripherally with a rim (13) surrounding the second lower plate (3) of the arrangement of two plates (2 and 3) superimposed when it rests on said receiving surface (5), the height (h) of said rim (13) corresponding to the thickness (1) of said second lower plate (3) and a peripheral sealing gasket (8) being mounted or formed on said rim (13) and configured to achieve an airtight seal between the first upper plate (2) and this rim (13).

[0028] As shown in Figures 2 and 3, the sealing means (8) may for example consist of a compression seal with a circular cross-section, mounted in a groove present in the rim (13) of the base plate (4').

[0029] Although it may consist of a frame attached peripherally around the receiving surface (5), the rim (13) is preferably formed in one piece with the base plate (4'), the latter also advantageously integrating said at least one fluidic connection line (11) connected to the means (9) of air suction or vacuum generator and opening at the level of said receiving surface (5).

[0030] In the variant of [Fig.2], no specific clamping means is implemented to hold the upper plate (2) against the base plate (4'), the holding being favorably ensured by the suction effect of the relative vacuum.

[0031] To possibly guarantee additional support and in particular also allow for possible pre-assembly of the arrangement of overlapping plates (2 and 3) on the base plate (4'), the installation (1) may further include, as shown in [Fig. 3], a frame (14) with a rebate conforming to the shape of the rim (13) and which can be removably fixed or applied under pressure to this rim (13), so as to sandwich with clamping the peripheral lateral edge (2') of the first upper plate (2) between this frame (14) and the rim (13), with compression of the peripheral sealing joint (8) mounted in or formed on said rim (13).

[0032] In accordance with another embodiment illustrated in [Fig.4], and not having a rim (13), the support structure (4) may include a base plate (4') having the receiving surface (5) and on which is fixed, in a removable manner, a peripheral frame (14) attached, configured to surround the arrangement of two superimposed plates (2 and 3) and to engage with the peripheral lateral edge (2') of the first upper plate (2) to achieve airtightness between the first upper plate (2) and the receiving surface (5) in cooperation with two sealing gaskets (8 and 8').

[0033] As shown in [Fig. 4] by way of example, the sides of the frame (14) can be made up of profiled portions defining a rebate that can receive the superimposed peripheral lateral edges (2' and 3') of the arrangement of the first and second superimposed plates (2 and 3), and have, for example, a common section substantially in the shape of an inverted L. The wings (15) corresponding to the horizontal arm of the profiled L on each side are engaged over the peripheral lateral edge (2') of the first upper plate (2), with compression of a first peripheral sealing gasket (8), on the one hand, and the wings (15') corresponding to the vertical arm of the L are fixed and bear with their lower end on the base plate (4'), with compression of a second peripheral sealing gasket (8'), on the other hand.The first sealing joint (8) may, for example, consist of a compressed sealing strip and the second joint (8') may consist of a compression joint with a circular cross-section, mounted in a peripheral groove of the base plate (4').

[0034] The support structure (4), with its base plate (4') and optionally its rim (13) and / or a frame (14), is configured and dimensioned in such a way that at least the second lower plate (3) and preferably also the first upper plate (2) are not physically constrained in its (their) principal plane (possibility of displacement / expansion in this plane in case of dimensional expansion by heating due to the action of the laser - provision of a peripheral lateral clearance).

[0035] The invention also relates, in relation to the different embodiments of the installation (1) described and illustrated, to a method of assembling by laser welding, face to face, two metal parts (2 and 3) in the form of flat plates, of which at least one first plate (2) has a continuous constitution.

[0036] This method implements an installation (1) which includes a support structure (4) comprising a base plate (4') with a receiving surface (5) for the two plates (2 and 3) to be assembled, and at least one laser welding head (6) which can be moved, in particular automatically by a robotic device (7) and under the control of a control unit (7'), relative to said receiving surface (5). This installation (1) further comprises at least one peripheral airtight sealing means (8), configured to provide a seal between the first upper plate (2) and the receiving surface (5), and the support structure (4) incorporating, or being connected to, an air intake means (9) or vacuum generator, which is in fluidic communication with the receiving surface (5) and the peripheral lateral linear opening (10) of the interstitial plane (PI) between the two superimposed plates (2 and 3). Advantageously, the implemented installation (1) comprises at least some of the features mentioned above.

[0037] This method is characterized in that it consists of placing the two plates (2 and 3) on the receiving surface (5), in a superimposed manner with the first plate (2) in the upper position and with indexing in position relative to each other, of achieving a peripheral airtight seal between the first upper plate (2) and the receiving surface (5), of generating a relative vacuum between said first upper plate (2) and said receiving surface (5), of activating said at least one laser welding head (6) and moving it above said first upper plate (2), preferably in a plane (PP) parallel to said receiving surface (5) and advantageously in accordance with a pre-programmed movement path, of removing the relative vacuum when the welding operation is completed, of releasing the two plates (2 and 3) assembled together and of removing them from the support structure (4).

[0038] Of course, the invention is not limited to the embodiments described and shown in the accompanying drawings. Modifications remain possible, particularly with regard to the composition of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

1. Demands Laser welding installation (1) for the mutual assembly, face to face, of two metal parts (2 and 3) in the form of flat plates, said installation (1) comprising a support structure (4) with a receiving surface (5) for the two plates (2 and 3) to be assembled, arranged in a superimposed manner and of which at least one first upper plate (2) has a continuous constitution, and at least one laser welding head (6) capable of being moved, in particular automatically by a robotic device (7) and under the control of a control unit (7'), relative to said receiving surface (5) and above said first upper plate (2) of the arrangement of two superimposed plates (2 and 3), preferably in a plane (PP) parallel to said receiving surface (5) and advantageously in accordance with a preprogrammed movement path,said installation (1) comprising at least one peripheral air-sealing means (8), configured to achieve a seal between the first upper plate (2) and the receiving surface (5) and the support structure (4) incorporating, or being connected to, an air suction means (9) or vacuum generator, which is in fluidic communication with the receiving surface (5) and the peripheral lateral linear opening (10) of the interstitial plane (PI) between the two superimposed plates (2 and 3), installation (1) characterized in that the receiving surface (5) has a network of channels (12), mutually interconnected and arranged according to a determined pattern, in that said network is fluidically connected to the air suction means (9) or vacuum generator by at least one connecting line (11),opening into said network through at least one opening (11') located beyond the lateral edge (3') of the second lower plate (3) and / or through at least one opening (11”) opening below the second lower plate (3), when an arrangement of superimposed plates (2 and 3) is disposed on the receiving surface (5), and in that the channel network (12), for example grooves formed in the surface of the base plate (4'), and the location scheme of the weld line(s) are determined correlatively so as to avoid any crossing between a channel and a line.

2. Welding installation according to claim 1, characterized in that the support structure (4) comprises a base plate (4') having the receiving surface (5) and connected to the means (9) of air suction or vacuum generator by at least one fluidic connection line (11) opening at the level of said receiving surface (5), under the second lower plate (3) of the arrangement of two superimposed plates (2 and 3) and / or beyond the lateral edge (3') of this second lower plate (3).

3. Welding installation according to claim 1 or 2, characterized in that the receiving surface (5) has a plurality of through openings fluidly connected by means (9) of air suction or vacuum generator, by at least one connecting line (11), and distributed over this surface (5) homogeneously or according to a predefined pattern, at least one (11') of said openings being located beyond the lateral edge (3') of the second lower plate (3), when the arrangement of superimposed plates (2 and 3) is disposed on the receiving surface (5), and within the perimeter delimited by said at least one sealing means (8).

4. Welding installation according to any one of claims 1 to 3, characterized in that the receiving surface (5) is provided peripherally with a rim (13) surrounding the second lower plate (3) of the arrangement of two superimposed plates (2 and 3) when it rests on said receiving surface (5), the height (h) of said rim (13) corresponding to the thickness (1) of said second lower plate (3) and a peripheral sealing gasket (8) being mounted or formed on said rim (13) and configured to achieve an airtight seal between the first upper plate (2) and this rim (13).

5. Welding installation according to claims 2 and 4, characterized in that the rim (13) is formed in one piece with the base plate (4'), the latter advantageously integrating said at least one fluidic connection line (11) connected to the means (9) of air suction or vacuum generator and opening at the level of said receiving surface (5).

6. A welding installation according to any one of claims 4 and 5, characterized in that it further comprises a frame (14) with a rebate conforming to the shape of the rim (13) and capable of being fixed, removably, or applied under pressure to this rim (13), so as to sandwich with clamping the peripheral lateral edge (2') of the first upper plate (2) between this frame (14) and the rim (13), with compression of the peripheral sealing gasket (8) mounted in or formed on said rim (13).

7. Welding installation according to any one of claims 1 to 3, characterized in that the support structure (4) comprises a base plate (4') having the receiving surface (5) and on which is fixed, in a removable manner, a peripheral frame (14) attached, configured to surround the arrangement of two superimposed plates (2 and 3) and to engage with the peripheral lateral edge (2') of the first upper plate (2) to achieve airtightness between the first upper plate (2) and the receiving surface (5) in cooperation with two sealing gaskets (8 and 8').

8. Welding installation according to claim 7, characterized in that the sides of the frame (14) are made up of profiled portions defining a rebate capable of receiving the superimposed peripheral lateral edges (2' and 3') of the arrangement of the first and second superimposed plates (2 and 3), and have, for example, a common section substantially in the shape of an inverted L, the wings (15) corresponding to the horizontal arm of the profiled L on each side coming into contact over the peripheral lateral edge (2') of the first upper plate (2), with compression of a first peripheral sealing gasket (8), on the one hand, and the wings (15') corresponding to the vertical arm of the L being fixed and coming into contact with their lower end on the base plate (4'), with compression of a second peripheral sealing gasket (8'), on the other hand.

9. A method for assembling, face to face, two metal parts (2 and 3) in the form of flat plates by laser welding, of which at least one first plate (2) has a continuous constitution, said method employing an installation (1) which includes a support structure (4) comprising a base plate (4') with a receiving surface (5) for the two plates (2 and 3) to be assembled, and at least one laser welding head (6) which can be moved, in particular automatically by a robotic device (7) and under the control of a control unit (7'), relative to said receiving surface (5), said installation (1) further comprising at least one peripheral air-sealing means (8), configured to achieve a seal between the first upper plate (2) and the receiving surface (5), and the support structure (4) incorporating, or being connected to, an air intake means (9) or vacuum generator, which is in fluidic communication with the receiving surface (5) and the peripheral lateral linear opening (10) of the interstitial plane (PI) between the two superimposed plates (2 and 3), and the receiving surface (5) having a network of channels (12), mutually interconnected and arranged according to a determined pattern, in that said network is fluidically connected to the air intake means (9) or vacuum generator by at least one connecting line (11),opening into said network through at least one opening (11') located beyond the lateral edge (3') of the second lower plate (3) and / or through at least one opening (11”) opening below the second lower plate (3), method characterized in that it consists of placing the two plates (2 and 3) on the receiving surface (5), in a superimposed manner with the first plate (2) in the upper position and with indexing in position relative to each other, of achieving a peripheral airtight seal between the first upper plate (2) and the receiving surface (5), of generating a relative vacuum between said first upper plate (2) and said receiving surface (5), of activating said at least one laser welding head (6) and moving it above said first upper plate (2), preferably in a plane (PP) parallel to said receiving surface (5) and in accordance with a pre-programmed movement path, the channel network (12),for example grooves formed in the surface of the base plate (4'), and the location scheme of the weld line(s) being determined correlatively so as to avoid any crossing between a channel and a line, to eliminate the relative void when the welding operation is completed, to release the two plates (2 and 3) assembled together and to remove them from the support structure (4).

Images