Laser welding apparatus and method, for the mutual assembly of two metal parts

Abstract

The invention relates to a laser welding apparatus (1) for the mutual assembly, face-to-face, of two metal parts (2, 3) in the form of flat plates, which apparatus comprises a support structure (4) with a receiving surface (5) for receiving the two plates (2, 3) to be assembled, and at least one laser welding head (6) that can be moved relative to the receiving surface (5) and above the first upper plate (2). This apparatus (1) further comprises at least one peripheral airtight sealing means (8) configured to produce a seal between the first upper plate (2) and the receiving surface (5), and the support structure (4) incorporates an air suction or vacuum generator means (9), which is in fluid communication with the receiving surface (5) and the peripheral lateral linear opening (10) in the interstitial plane (PI) between the two stacked plates (2, 3).

Description

Description LASER WELDING INSTALLATION AND PROCESS FOR THE MUTUAL ASSEMBLY 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 for the purpose of 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 welding is carried out by mechanical blocking (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 bead, the welding sequence or similar parameters, and must make it possible to manage the expansions and warping between parts inherent in welding processes, in particular fusion welding.

[0004] It is essential to find an acceptable compromise 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 unwanted deformations in the assembled composite part).

[0005] In addition to the two most common types of clamping mentioned above, vacuum clamping embodiments are also known, which also make it possible to improve the quality of the weld (the removal of air in contact with the weld pool significantly reduces the oxygen and hydrogen concentration and leads to a reduction in the porosity rate and a stabilization of the "keyhole" produced by the laser beam at the point of impact). In the state of the art, for example, in connection with this vacuum clamping technique, a welding installation is known with a workpiece holding device and a laser welding device which are both housed in a hermetic enclosure (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 allows a good compromise to be found between the two opposing requirements mentioned above, the installations used are complex, bulky, expensive and unsuitable for large flat parts, such as plates.

[0007] The main aim of the present invention is to overcome the various drawbacks 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 which can be moved, in particular automatically by a robotic device and under the control of a control unit, relatively 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 preprogrammed movement route, installation characterized in that it comprises at least one peripheral air sealing means,configured to provide a seal between the first upper plate and the receiving surface and in that the support structure incorporates, or is connected to, an air suction or vacuum generator means, which is in fluid communication with the receiving surface and the peripheral lateral linear opening of the interstitial plane between the two superimposed plates.,

[0009] The invention will be better understood from the following description, which relates to preferred embodiments, given as non-limiting examples, and explained with reference to the appended schematic drawings, in which:

[0010] [Fig. 1] is a schematic top view of a laser welding assembly installation according to the invention, with a welding head, for assembling a first upper plate with a second lower plate;

[0011] [Fig. 2], [Fig. 3] and [Fig. 4] are schematic representations in section along AA of the installation shown in figure 1, illustrating three variant embodiments of the invention;

[0012] [Fig. 5] is a partial sectional view along BB of the installation shown in Figure 1, illustrating a fourth variant embodiment of the invention;

[0013] [Fig. 6] is a top and perspective view of a first embodiment of a base plate with its network of grooves at the bearing surface, which may form part of an installation as shown in any one of Figures 2 to 5;

[0014] [Fig. 7] is a top and perspective view of a second embodiment of a base plate with its network of grooves at the bearing surface, which may form part of an installation as shown in any one of Figures 2 to 5;

[0015] [Fig. 8A] is a view similar to that of Figure 7 showing a second lower plate resting on the base plate and illustrating by virtual projection the pattern of the weld lines intended to assemble this plate with a first upper plate;

[0016] [Fig. 8B] is a view similar to that of Figures 7 and 8A, at another scale, showing by superposition the relative arrangement between the network of grooves of Figure 7 (in thicker lines) and the pattern of weld lines of Figure 8A (in thinner lines);

[0017] [Fig. 8C] is a sectional view along CC of the base plate shown in Figure 8B, and on which rest first and second plates welded together according to the weld line pattern of Figures 8;

[0018] [Fig. 9] is a top and perspective view of a third embodiment of a base plate with its network of grooves at the bearing surface, which may form part of an installation as shown in any one of Figures 2 to 5;

[0019] [Fig. 10A] is a view similar to that of Figure 9 showing a second lower plate resting on the base plate and illustrating by virtual projection the pattern of the weld lines intended to assemble this plate with a first upper plate;

[0020] [Fig. 10B] is a view similar to that of Figures 9 and 10A showing by superposition the relative arrangement between the network of grooves of Figure 9 (in thicker lines) and the pattern of weld lines of Figure 10A (in thinner lines).

[0021] Figures 1 to 5 schematically illustrate several variants 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.

[0022] 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 superimposed 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 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'), relatively 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.

[0023] According to the invention, this installation (1) also comprises at least one peripheral air sealing means (8), configured to provide 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 or vacuum generator means (9), which is in fluid 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).

[0024] Thanks to the above inventive provisions, a relative vacuum enclosure is provided ensuring forced application of the two plates (2 and 3) of the superimposed arrangement against each other and locking in position of said arrangement on the receiving surface (5). Given the configuration of the installation (1), access from above to the first upper plate (2) is completely clear, possibly with the exception of a thin peripheral strip (see figures 3 and 4) not affected by the assembly operation. In addition, the application of the vacuum being made from below and laterally at the level of the two plates to be assembled and no means relating to the vacuum clamping being located in the volume above the upper plate (2), there is no risk of interference or limitation of movement in relation to said at least one laser welding head (6). Finally, the overall size of the installation (1) is limited.

[0025] 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 mobile head (or scanner head) and / or a fixed head moved by a suitable device.

[0026] It should be noted that the or each weld line (6') produced by the action of the laser welding head(s) (6) may be continuous or segmented. In the case of the subsequent production (by hydroforming for example) of liquid circulation channels between the two plates (2 and 3) to be assembled, these weld lines (6') are preferably continuous.

[0027] The second lower plate (3) is preferably also structurally continuous, and the two plates advantageously have substantially rectangular shapes, of the same size or not (larger upper plate). However, this second plate (3) may also have openings (of course outside the weld lines 6') 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 contact under pressure of the two plates (2 and 3) under the effect of the partial vacuum between them produced by the suction at the peripheral lateral linear opening (10), or slot opening onto the outside, of the interstitial plane (PI) between the two superimposed plates (2 and 3).

[0028] Advantageously, the support structure (4) comprises a base plate (4') having the receiving surface (5) and connected to the air suction or vacuum generator means (9) by at least one fluid 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').

[0029] This or each connection line (1 1 ) may be at least partially formed or hollowed out in the base plate (4') (see figures 2 to 4 and 8C), namely at least for its terminal part. In the case of a plurality of connection lines (1 1 ), each may have an outlet opening (1 1 ', 1 1 ”) opening out. The means (9) may be mounted on the support structure (4) or be separated from the latter (it may possibly be a suction outlet of a network extending over the site receiving the installation (1 ), connected to the base plate (4) by a conduit).

[0030] Depending on the configuration of the base plate (4') and the relative dimensions of the first and second plates of the arrangement, the sealing 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 at least two or 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 Figure 4.

[0031] In accordance with an alternative embodiment, emerging from Figure 5 and ensuring effective vacuuming, the receiving surface (5) has a plurality of through openings (11', 11”) fluidly connected to the air suction or vacuum generator means (9), by at least one connection line (11), and distributed over this surface (5) in a homogeneous manner 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 surface of reception (5), and within the perimeter delimited by said at least one sealing means (8).

[0032] As shown in Figures 2 to 10 as non-limiting exemplary embodiments, and in order to achieve a substantially homogeneous distribution of the suction effect of the relative vacuum, the receiving surface (5) has a network of channels (12), mutually interconnected and arranged in a determined pattern. This network (12) is fluidically connected to the air suction or vacuum generating means (9) by at least one connecting line (11), opening into said network of channels (12) 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 under the second lower plate (3), when an arrangement of superimposed plates (2 and 3) is arranged on the receiving surface (5).

[0033] As shown in Figure 6, the network of interconnected channels (12) may extend in the form of a regular 2D grid of perpendicular and intersecting lines, over the entire extent of the receiving surface (5) included within the perimeter delimited by said at least one peripheral air sealing means (8), mounted in the base plate (4') or in an attached peripheral frame (14).

[0034] Preferably, however, according to a favorable characteristic of the invention and as shown in Figures 7 to 10, this network of channels (12), for example grooves formed in the surface of the base plate (4'), and the location pattern or pattern of the weld line(s) (6') are determined correlatively and configured so as to avoid any crossing between a channel (12) and a weld line (6').

[0035] Thus, for a given pattern or diagram of welding lines (6'), dictated by the shape of the plates (2 and 3) to be assembled and the configuration of the liquid circulation circuit(s) to be produced between these two plates, the base plate (4') used has an interconnected network of channels (12) whose configuration, as well as the distribution and arrangement on the distribution surface, are such that this network extends in a substantially regular manner under the second lower plate (3), but without a welding line (6') being able to pass above a channel (12) by crossing it or cutting it, or extending parallel to it. above it. This results, as shown for example in Figure 8B and Figure 10B, in two mutually interlocking, but non-interfering, patterns or networks of lines when considered in mutual superposition.

[0036] By avoiding any crossing (viewed along the vertical direction of application of the laser) between the channels (12) and the welding lines (6'), any possible influence of the suction prevailing in the channels (12) on the welding bead being formed is avoided (in particular the phenomenon of deformation, or even suction, at the right of a channel, in the presence of thin plates). At the same time, any discontinuity in the support of the plates at the right of the mobile application point of the laser beam (FLC) is avoided.

[0037] More precisely and even more favorably, it may be provided, in addition to an absence of crossing, that the channels (12) and the weld lines (6') are configured and arranged relatively to each other in such a way that the same minimum distance separates substantially each channel (12) from said at least one weld line (6') closest to it. Figures 8B and 10B illustrate two practical non-limiting examples of producing such networks of channels and weld lines that are mutually nested and substantially equidistant. It is then possible to ensure relative homogeneity or thermal uniformity along the entire path of the laser beam (FLC) during the assembly process.The layout of the channels (12) is thus normally determined according to the layout of the weld lines (6') to be produced, although the latter may, if necessary, be at least slightly adjusted according to possible manufacturing or operating constraints (interdependent determination).

[0038] As shown in particular in Figures 8 and 10, the interconnected network of channels (12) is advantageously located entirely under the second lower plate (3) and connected to a single suction opening (11”) also located under this plate. The peripheral seal (8) and the first continuous upper plate (2) together provide a sealed enclosure for holding the second lower plate (3) against the receiving surface (5) and the two plates (2 and 3) firmly clamped against each other during the welding assembly phase.

[0039] In accordance with a constructive variant of the invention, emerging from 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 superimposed plates (2 and 3) when the latter rests on said receiving surface (5), the height (h) of said rim (13) corresponding to the thickness (I) of said second lower plate (3) and a peripheral seal (8) being mounted or formed on said rim (13) and configured to provide an airtight seal between the first upper plate (2) and this rim (13).

[0040] As shown in Figures 2 and 3, the sealing means (8) may for example consist of a compression seal with a circular section, mounted in a groove present in the rim (13) of the base plate (4').

[0041] Although it may consist of a frame attached peripherally to the periphery of the receiving surface (5), as indicated below, the rim (13) may be formed in one piece with the base plate (4'), the latter further advantageously integrating said at least one fluid connection line (11) connected to the air suction or vacuum generator means (9) and opening out at said receiving surface (5).

[0042] In the variant of figure 2, no specific clamping means is used to hold the upper plate (2) against the base plate (4'), the holding being favorably ensured by the suction effect of the relative vacuum.

[0043] To possibly ensure additional support and in particular also to allow a possible wedged and secure pre-assembly of the arrangement of superimposed plates (2 and 3) on the base plate (4'), the installation (1) may further comprise, as shown in Figure 3, a frame (14) with a rebate matching the shape of the edge (13) and which can be fixed, in a removable manner, or be applied under pressure to this edge (13), so as to sandwich with tightening the peripheral lateral edge (2') of the first upper plate (2) between this frame (14) and the rim (13), with compression of the peripheral seal (8) mounted in or formed on said rim (13).

[0044] In accordance with another embodiment illustrated in Figure 4, and not having a rim (13), the support structure (4) may comprise a base plate (4') having the receiving surface (5) and on which is fixed, in a removably manner, a peripheral frame (14) attached, configured to surround the arrangement of two superimposed plates (2 and 3) and to come into engagement with the peripheral lateral edge (2') of the first upper plate (2) to achieve air sealing between the first upper plate (2) and the receiving surface (5) in cooperation with two seals (8 and 8').

[0045] As shown in Figure 4 by way of example, the sides of the frame (14) may consist 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 having, for example, a running section substantially in the shape of an inverted L. The wings (15) corresponding to the horizontal branch of the profiled L on each side come into engagement over the peripheral lateral edge (2') of the first upper plate (2), with compression of a first peripheral seal (8), on the one hand, and the wings (15') corresponding to the vertical branch of the L being fixed and bearing with their lower end on the base plate (4'), with compression of a second peripheral seal (8'), on the other hand.The first sealing gasket (8) may for example consist of a compressed sealing strip and the second gasket (8') may consist of a compression gasket with a circular section, mounted in a peripheral groove of the base plate (4').

[0046] In accordance with a preferred embodiment of the invention, derived from the embodiment shown in Figure 4 and illustrated by way of example in Figure 5, the support structure (4) comprises an attached peripheral frame (14), resting on the base plate (4'), delimiting the receiving surface (5) and configured to surround the arrangement of two superimposed plates (2 and 3), substantially without contact with their respective lateral edges (2' and 3'), and to come into engagement from above with the peripheral lateral edge (2') of the first upper plate (2). This frame (14) forms with this first upper plate (2) and the base plate (4') and by means of at least two sealing joints (8 and 8'), an airtight enclosure enclosing the second lower plate (3).

[0047] In order to prevent them from being soiled by particles generated by the welding process, it is advantageously provided that said at least two sealing gaskets (8, 8') - and advantageously all the peripheral gaskets (8, 8', 8”) present - are all (two or three) mounted in the frame (14), a first gasket (8) providing the seal between said frame (14) and the upper surface of the lateral edge (2') of the first upper plate (2) and at least one second gasket (8'; 8', 8”) providing the seal between said frame (14) and the base plate (4'), where appropriate a third gasket (8”) doubling said second gasket (8').

[0048] To facilitate the construction and implementation of the installation (1), the frame (14) can, during the assembly process, be held rigidly and under pressure against the base plate (4) - only - by suction effect generated by the air suction or vacuum generator means (9). To make its precise positioning less tedious, said frame (14) can advantageously be geometrically prepositioned on the base plate (4') by indexing means (lugs in holes) or by an articulated connection connecting the two together (hinge).

[0049] As a practical construction, also apparent from Figure 5, the frame (14) is preferably made in one piece and may have a rebate (14'), in which a first sealing joint (8) is mounted in a wedged and fixed manner and which is intended to receive, with the interposition of said joint (8), the superimposed lateral edges (2' and 3') of the first and second plates (2 and 3).

[0050] In order to protect the peripheral sealing means from the laser beam and from possible projections during its passage near the edge areas of the plates, the frame (14) comprises, along the outer edge of the rebate (14'), a wing (14”) extending said edge, this wing (14”) forming with the bottom of the rebate (14') a groove receiving a first sealing joint (8) and having in cross section a hooked nose shape (figure 5).

[0051] The support structure (4), with its base plate (4') and possibly 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) is / are not physically constrained in its / their main plane (possibility of displacement / expansion in this plane in the event of dimensional expansion by heating due to the action of the laser - provision of peripheral lateral clearance).

[0052] In addition, an air circulation duct systematically exists between the lateral edges (2' and 3') of the superimposed plates (2 and 3) and the rim (13) or frame (14) which surrounds them, and this over the entire perimeter of said plates (2 and 3).

[0053] For the sake of thermal control, to avoid any inappropriate deformation of the two plates (2 and 3), but also to avoid unwanted heating of the support structure (4) and its equipment, a system for evacuating the calories generated during welding, especially over a long period, is desirable.

[0054] To this end, the invention proposes that the base plate (4') comprises, in its thickness, a temperature regulation circuit (16), formed of liquid circulation channels (16') extending under the receiving surface (5) and connected to an external source of heat transfer liquid by ports (16”) located on the periphery or on the underside of the base plate (4'), the latter being advantageously formed of two constituent parts (17, 17') assembled in a sealed manner (see figure 5 as an example). The base plate (4) is thus subdivided into two constituent parts along its edge, the upper part (17) comprising the receiving surface (5) with the channels (12) and the two parts (17 and 17') forming the channels (16') by cooperation.

[0055] The invention also relates, in relation to the various 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.

[0056] This method uses an installation (1) which comprises 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'), relatively to said receiving surface (5). This installation (1) further comprises at least one peripheral air sealing means (8), configured to perform a sealing between the first upper plate (2) and the receiving surface (5), and the support structure (4) integrating, or being connected to, an air suction or vacuum generator means (9), which is in fluid 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 installation (1) implemented comprises at least some of the characteristics mentioned above.

[0057] 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, in creating a peripheral airtight seal between the first upper plate (2) and the receiving surface (5), in generating a relative vacuum between said first upper plate (2) and said receiving surface (5), in 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 route, in removing the relative vacuum when the welding operation is completed, in releasing the two plates (2 and 3) assembled together and in removing them from the support structure (4).

[0058] Preferably, the installation used for the implementation of this method is an installation (1) as described previously.

[0059] Of course, the invention is not limited to the embodiments described and shown in the attached drawings. Modifications remain possible, particularly from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Claims

1. 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) which can be moved, in particular automatically by a robotic device (7) and under the control of a control unit (7'), relatively 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,installation (1) characterized in that it comprises at least one peripheral air sealing means (8), configured to provide a seal between the first upper plate (2) and the receiving surface (5) and in that the support structure (4) incorporates, or is connected to, an air suction or vacuum generator means (9), which is in fluid 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).,

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 air suction or vacuum generator means (9) by at least one fluid 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 fluidically connected to the air suction or vacuum generator means (9), by at least one connection line (11), and distributed over this surface (5) in a homogeneous manner or according to a predefined pattern, at least one (1 1 ') 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 arranged on the receiving surface (5), and inside the perimeter delimited by said at least one sealing means (8).

4. Welding installation according to claim 1 or 2, characterized in that the receiving surface (5) has a network of channels (12), mutually interconnected and arranged in a determined pattern, said network being fluidically connected to the air suction or vacuum generator means (9) by at least one connection 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 under the second lower plate (3), when an arrangement of superimposed plates (2 and 3) is arranged on the receiving surface (5).

5. Welding installation according to claim 4, characterized in that the network of channels (12), for example grooves formed in the surface of the base plate (4'), and the location pattern or pattern of the welding line(s) (6') are determined correlatively and configured so as to avoid any crossing between a channel (12) and a welding line (6').

6. Welding installation according to claim 5, characterized in that the channels (12) and the welding lines (6') are configured and arranged relative to each other in such a way that the same minimum distance separates each channel (12) from said at least one welding line (6') closest to it.

7. Welding installation according to any one of claims 1 to 6, 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 the latter rests on said receiving surface (5), the height (h) of said rim (13) corresponding to the thickness (I) of said second lower plate (3) and a peripheral seal (8) being mounted or formed on said rim (13) and configured to provide an airtight seal between the first upper plate (2) and this rim (13).

8. Welding installation according to claims 2 and 7, characterized in that the rim (13) is formed in one piece with the base plate (4'), the latter advantageously integrating said at least one fluid connection line (11) connected to the air suction means (9) or vacuum generator and opening at said receiving surface (5).

9. Welding installation according to any one of claims 7 and 8, characterized in that it further comprises a frame (14) with a rebate matching the shape of the rim (13) and capable of being fixed, in a removable manner, or being 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).

10. Welding installation according to any one of claims 1 to 6, characterized in that the support structure (4) comprises a base plate (4') having the receiving surface (5) and on which is fixed, in a removably manner, a peripheral frame (14) attached, configured to surround the arrangement of two superimposed plates (2 and 3) and to come into engagement with the peripheral lateral edge (2') of the first upper plate (2) to achieve air sealing between the first upper plate (2) and the receiving surface (5) in cooperation with two sealing gaskets (8 and 8'). [Claim 1 1] Welding installation according to claim 10, 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 running section substantially in the shape of an inverted L, the wings (15) corresponding to the horizontal branch of the profiled L on each side coming into engagement over the peripheral lateral edge (2') of the first upper plate (2), with compression of a first peripheral sealing joint (8), on the one hand, and the wings (15') corresponding to the vertical branch of the L being fixed and coming to bear with their lower end on the base plate (4'), with compression of a second peripheral sealing joint (8'), on the other hand.

12. Welding installation according to any one of claims 1 to 6, 10 or 1 1, characterized in that the support structure (4) comprises an attached peripheral frame (14), resting on the base plate (4'), delimiting the receiving surface (5) and configured to surround the arrangement of two superimposed plates (2 and 3), substantially without contact with their respective lateral edges (2' and 3'), and to come into engagement from above with the peripheral lateral edge (2') of the first upper plate (2), said frame (14) forming with this first upper plate (2) and the base plate (4') and by means of at least two sealing joints (8 and 8'), an airtight enclosure enclosing the second lower plate (3).

13. Welding installation according to claim 12, characterized in that said at least two sealing gaskets (8, 8') are both mounted in the frame (14), a first gasket (8) providing the seal between said frame (14) and the upper surface of the lateral edge (2') of the first upper plate (2) and at least one second gasket (8') providing the seal between said frame (14) and the base plate (4'), where appropriate a third gasket (8”) doubling said second gasket (8').

14. Welding installation according to claim 12 or 13, characterized in that the frame (14) is held rigidly and under pressure against the base plate (4) by suction effect generated by the air suction or vacuum generator means (9), said frame (14) being able to be advantageously geometrically prepositioned on the base plate (4') by indexing means or by an articulated connection connecting the two.

15. Welding installation according to any one of claims 12 to 14, characterized in that the frame (14) has a rebate (14'), in which a first sealing joint (8) is mounted in a wedged and fixed manner and which is intended to receive, with the interposition of said joint (8), the superimposed lateral edges (2' and 3') of the first and second plates (2 and 3).

16. Welding installation according to claim 15, characterized in that the frame (14) comprises, along the outer edge of the rebate (14'), a wing (14”) extending said edge, this wing (14”) forming with the bottom of the rebate (14') a groove receiving a first seal (8) and having in cross section a hooked nose shape.

17. Welding installation according to any one of claims 1 to 16, characterized in that the base plate (4') comprises, in its thickness, a temperature regulation circuit (16), formed of liquid circulation channels (16') extending under the receiving surface (5) and connected to an external source of heat transfer liquid by ports (16”) located on the periphery or on the underside of the base plate (4'), the latter being advantageously formed of two constituent parts (17, 17') assembled in a sealed manner.

18. Method for 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, said method implementing an installation (1) which comprises 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'), relatively to said receiving surface (5), said installation (1) further comprising at least one peripheral air sealing means (8), configured to provide a seal between the first upper plate (2) and the receiving surface (5), and the support structure (4) integrating, or being connected to,an air suction or vacuum generator means (9), which is in fluid 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), 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, to achieve a peripheral airtight seal between the, first upper plate (2) and the receiving surface (5), generating a relative vacuum between said first upper plate (2) and said receiving surface (5), 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 route, removing the relative vacuum when the welding operation is completed, releasing the two plates (2 and 3) assembled together and removing them from the support structure (4).

19. Method according to claim 18, characterized in that the installation (1) implemented is an installation according to any one of claims 1 to 17.

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