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 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 methods are also known, which also make it possible to improve the quality of the weld (the removal of air in contact with the molten pool greatly 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, both of which are 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 workpieces to be welded (see, for example, CN108637470).

[0006] However, and although this clamping technique makes it possible to find a good compromise between the two opposing requirements mentioned above, the installations implemented 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,

[0009] 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 integrates, 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.

[0010] 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:

[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 representations in section along AA of the installation shown [Fig.l], illustrating three variant embodiments of the invention;

[0013] [Fig.5] is a top and perspective view of an embodiment of a plate base with its network of grooves at the level of the support 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 variant embodiments 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 least one head laser welding (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 pre-programmed movement route.

[0016] 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).

[0017] Thanks to the above inventive arrangements, 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). Taking into account 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 concerned 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 in relation to the vacuum clamping being located in the volume above the upper plate (2), there is no risk of interference or limitation of the movement in relation to said at least one laser welding head (6). Finally, the general size of the installation (1) is limited.

[0018] The variants of the installation (1) shown only comprise 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.

[0019] It should be noted that the or each weld line produced by the action of the laser welding head(s) (6) may 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 (larger upper plate). However, it can also have openings (of course 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 contact under pressure of the two plates (2 and 3) under the effect of the partial vacuum between them does not produce suction at the level of the peripheral lateral linear opening (10), or slot opening onto the exterior, 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 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').

[0022] This or each connection line (11) may be at least partially formed or hollowed out in the base plate (4') (see figures 2 to 4), namely at least for its terminal part. In the case of a plurality of connection lines (11), each may have an outlet opening (11', 11”) 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).

[0023] 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 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, emerging from [Fig. 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 receiving surface (5), and inside 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 suction effect of the relative vacuum, the receiving surface (5) has a network of channels (12), mutually inter connected and arranged in a determined pattern. This network (12) is fluidically connected to the air suction or vacuum generator 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).

[0026] Preferably, the network of channels (12), for example grooves formed in the surface of the base plate (4'), and the location pattern of the welding 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, 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 (1) 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).

[0028] 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').

[0029] Although it may consist of a frame attached peripherally to the periphery of 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 fluid connection line (11) connected to the air suction or vacuum generator means (9) and opening out at 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 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 [Fig. 3], 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 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 sealing gasket (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 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 sealing gaskets (8 and 8').

[0033] As shown in [Fig. 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 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 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 coming to bear 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').

[0034] 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 a peripheral lateral clearance).

[0035] 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.

[0036] This method implements 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 surface of reception (5). This installation (1) further comprises at least one peripheral air sealing means (8), configured to provide a seal between the first upper plate (2) and the reception surface (5), and the support structure (4) incorporating, or being connected to, an air suction or vacuum generator means (9), which is in fluid communication with the reception 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.

[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, in producing 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 preprogrammed 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).

[0038] Of course, the invention is not limited to the embodiments described and shown in the attached drawings. Modifications remain possible, in particular 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 (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 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 any one of claims 1 to 4, 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 (1) 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).

6. Welding installation according to claims 2 and 5, 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 the level of said receiving surface (5).

7. Welding installation according to any one of claims 5 and 6, 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).

8. Welding installation according to any one of claims 1 to 4, characterized in that the support structure (4) comprises a plate of

9.

10. base (4') having the receiving surface (5) and on which is fixed, in a removable manner, a peripheral frame (14), 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'). Welding installation according to claim 8, 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 seal (8), on the one hand, and the wings (15') corresponding to the vertical branch of the L being fixed and coming into abutment with their lower end on the base plate (4'), with compression of a second peripheral seal (8'), on the other hand. 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 putting the two in place, plates (2 and 3) on the receiving surface (5), this 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), to generate a relative vacuum between said first upper plate (2) and said receiving surface (5), to activate said at least one laser welding head (6) and to move it above said first upper plate (2), preferably in a plane (PP) parallel to said receiving surface (5) and advantageously in accordance with a preprogrammed movement route, to remove the relative vacuum 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).

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