Facility for cutting, welding, resurfacing or metal additive manufacturing by laser beam, comprising an inerting chamber housing an end effector of a robot and a turntable of a two-axis positioner

Abstract

The invention relates to a facility (1) for cutting, welding, recharging or additive manufacturing by laser beam, comprising a robotized mechanism with a two-axis positioner (4) while ensuring inerting in the inerting chamber (10) in which the laser beam is used for manufacturing, with very low O2 and H2O values.

Description

[0001] Description

[0002] Title: Installation for cutting, welding, recharging or metal additive manufacturing by laser beam comprising an inerting enclosure housing a robot end effector and a rotating plate of a two-axis positioner.

[0003] Technical field

[0004] The present invention relates mainly to the field of metal additive manufacturing.

[0005] More particularly, the invention relates to an improvement by robotization of an additive manufacturing process using a laser beam within an inerting enclosure.

[0006] Although described in particular with reference to a process for metal additive manufacturing by laser with wire input, with the English acronym WLAM for "Wire Laser Additive Manufacturing", the invention relates more generally to any process for cutting, welding, or resurfacing metal additive manufacturing, by laser beam in all industrial, engineering and part manufacturing fields, particularly in the nuclear field.

[0007] Prior art

[0008] The WLAM process is a relatively new process under development. This process allows parts or shapes to be designed using design software. A part is produced in layers to obtain the thinnest possible layers. The layers are then successively deposited by the additive manufacturing system. Thus, the WLAM process is comparable to traditional 3D printing, but with the use of a laser-melted metal wire instead of a nozzle-melted plastic wire.

[0009] Compared to selective laser melting (SLM) and laser melting deposition (LMD), a WLAM process has many advantages, including the fact that it is perfectly suited to designing large parts and could meet high production rates. The laser uses spots of 1 to 2 mm, producing much more localized heat. A WLAM process therefore makes it possible to build parts that could not be built using a wire arc additive manufacturing (WAAM).

[0010] In addition, the use of wire guarantees a 100% material yield.

[0011] In addition, in a WLAM process, the risks associated with the use of powder are eliminated. A WLAM process thus allows for a significant reduction in costs related to personal protective equipment and operator health monitoring.

[0012] Despite all the above advantages, the technological maturity level of a WLAM process is lower than for the WAAM process.

[0013] Generally speaking, laser welding and metal additive manufacturing processes differ primarily from arc processes such as TIG welding (Tungsten Inert Gas) or MIG welding (Metal Inert Gas) in that they are performed at higher welding speeds, higher power densities, and higher melting temperatures.

[0014] This involves significant temperature gradients around the molten pool, causing, by convection, polluted gas around the molten pool. This generates impurities which harm the technical performance of the parts produced: appearance of cracks, crevices, bubbles, impurities, etc.

[0015] In particular, in the case of a WLAM process, it is noted that the solutions usually used to carry out inerting do not limit the defects mentioned above. It should be noted here that inerting consists of using neutral gases such as argon, nitrogen, or helium. These neutral gases can ensure the quality of the parts produced by protecting the molten materials during production. It also allows the atmosphere to be controlled during the additive printing process.

[0016] Current inerting requires spraying very large quantities of gas with mixed results. In addition, the neutral gas (argon, nitrogen) used is lost by dispersing into the atmosphere.

[0017] Furthermore, the quality criteria required in certain application areas, such as low-carbon energy (nuclear or otherwise), require the absence of defects in the parts produced, sometimes made from special alloys. This involves inerting near the molten pool with very low O2 and H2O values, typically less than 10 ppm.

[0018] However, to date, these values ​​can only be obtained in a hermetic inerting enclosure which is rigid, that is to say with rigid walls which delimit it.

[0019] Figure 1 shows such a rigid enclosure 10 according to the state of the art, generally shaped like a rectangular parallelepiped: it is delimited by four side walls 11, 12, 13, 14, a lower wall 15, and an upper wall 16. To be able to easily move the enclosure, it can be provided with feet with casters 17. Portholes 18 are intended to receive gloves, not shown, for handling the parts, tools, manufacturing and to allow maintenance to be carried out on the additive manufacturing head. The manufactured parts can be evacuated, if their size allows it, through an airlock, which is the function of the part “projecting” on the outside.

[0020] Furthermore, robotization of cutting, welding, resurfacing or laser additive manufacturing installations would enable large movements in three dimensions and thus enable the rapid production of finished metal volumetric parts with complex geometries, in particular elliptical revolution-shaped parts or parts with functions added to cylindrical-shaped parts.

[0021] H is known for inerting enclosures including a robot within them. The inerting volume is then significantly larger, making the inerting of the enclosure longer and more expensive.

[0022] There is therefore a need to improve cutting, welding, recharging or additive manufacturing installations using a laser beam, in order to robotize them while making them compatible with implementation in an inerting enclosure, with very low O2 and H2O values, typically less than 10 ppm, which make it possible to increase the quality of the fusion baths, to increase the mechanical resistance of the manufactured parts to best comply with the standards in force.

[0023] The aim of the invention is to meet at least part of this need.

[0024] Statement of the invention

[0025] To do this, the invention relates, in one of its aspects, to an installation for cutting, welding, recharging or additive manufacturing by laser beam, comprising: - an inerting enclosure, under an inert atmosphere, delimited by at least one rigid wall and a first and a second flexible sealing skirts each fixed in a sealed manner to the at least one rigid wall;

[0026] - a robot end effector comprising a support at least a part, preferably its head, of at least one laser adapted to emit a cutting, welding, recharging or additive manufacturing beam and at least one sealed fixing flange, fixed or made integrally with the support and on which the first flexible sealing skirt is fixed in a sealed manner;

[0027] - a robot to which the robot end effector is attached, the robot being adapted to allow movement of the end effector inside the enclosure, in one and / or the other of the three orthogonal directions (X, Y, Z);

[0028] - a positioner with plate(s), with two axes, including an axis of rotation around one (Z) of the three directions and an axis of pivoting around another (Z) of the three directions, to respectively rotate and pivot, inside the enclosure, at least the upper plate around which the second flexible sealing skirt is fixed in a sealed manner, the upper plate forming a support for a part to be produced by cutting, welding or additive manufacturing.

[0029] The inerting gas to be injected can be argon or nitrogen.

[0030] By "two-axis positioner" is meant the usual meaning of the technology, namely a self-contained motorized device, equipped with a rotary axis and a tilting axis for positioning a part in space. In the context of the invention, the operation of the two-axis positioner is advantageously controlled by that of the robot and the laser supported by the robot's end effector.

[0031] According to an advantageous embodiment, the enclosure comprises five rigid walls delimiting a right parallelepiped with the exception of the upper opening to which the first flexible skirt is fixed in a sealed manner.

[0032] Advantageously, the robot is a six-axis articulated arm robot.

[0033] According to an advantageous embodiment, the positioner comprises:

[0034] - two rotating plates, the upper plate and a lower plate integral with each other and fixed to the rotation axis,

[0035] - at least one seal between the two rotating plates defining a sealed space, - a cooling plate, mounted in the sealed space and in which a heat transfer fluid can circulate so as to cool the upper plate.

[0036] Such an assembly not only ensures the rotation of the part to be produced on itself but also the efficient evacuation of heat through the base of the positioner.

[0037] Indeed, laser additive manufacturing cycles generate very high temperatures in the parts, especially since they can be long, typically from 1 to several dozen hours. However, the hermetic inerting enclosure confines the heat resulting from the melting of the materials to produce the parts, typically between 600 and 800°C. Thus, ensuring effective cooling as close as possible to the upper plate that supports the part allows for optimal thermal protection of the positioner components.

[0038] According to an advantageous embodiment variant, the positioner comprises a pivoting body, fixed on the pivoting axis and on which the upper plate is rotatably mounted.

[0039] According to an advantageous configuration, the lower rotary plate is mounted in rotation with contact with the pivot body.

[0040] Advantageously, the positioner includes a locking pin to limit the pivoting of the upper plate, preferably at a maximum angle of + / - 20° relative to the horizontal. Thus, the locking pin keeps the part on which the connections to the heat transfer fluid are installed fixed.

[0041] According to an advantageous embodiment variant, the sealed fixing flange houses at least one sealed passage for the laser power supply cable(s) or fiber(s), the electrical power supply, the fluid supply, in particular the inerting gas, the control and / or instrumentation cable(s).

[0042] According to this variant, the waterproof mounting flange also houses a waterproof passage for a wire feeder to be melted by the laser for welding or additive manufacturing, the feeder being fixed to the end effector support.

[0043] Preferably, the waterproof fixing flange is of generally circular shape, the periphery of which is fixed in a waterproof manner to the first flexible skirt.

[0044] More preferably, the laser is supported so that the axis of the beam it emits is centered on the center of the sealed fixing flange. According to another advantageous embodiment, the installation comprises at least one control-command unit for controlling the laser, the supply of the inerting gas and the movement of the robot and thus of the end effector in the enclosure.

[0045] In an advantageous configuration, the seal between the first flexible skirt and the rigid wall(s) on the one hand, and the sealed fixing flange on the other hand, is such that the O2 and H2O values ​​are less than 10 ppm within the inerting enclosure.

[0046] State-of-the-art laser cutting, welding and additive manufacturing processes enable high working speeds at high temperatures.

[0047] On the other hand, it has been noted that these processes generate more or less pollution, in particular dust(s) and / or smoke(s) from the molten pool generated by the laser, depending on the materials melted.

[0048] The inventors carried out thermodynamic analyses of inerting gases which showed that the very hot flows are violently disturbed and do not perform as well as possible what they are intended for, which deteriorates the quality of the inerting, and is therefore likely to cause defects during manufacturing.

[0049] However, the quality criteria required in certain fields require the absence of defects in the parts produced, sometimes made from special alloys.

[0050] This necessarily implies that the production of these parts is done with inerting near the molten pool with very low values, in O2 and H2O, typically less than 10 ppm.

[0051] To date, these values ​​can only be obtained in a rigid, hermetic inerting enclosure.

[0052] Furthermore, the robotization of current laser welding and additive manufacturing installations guarantees large movements in three dimensions and thus makes it possible to quickly produce finished metal volume parts with complex geometries.

[0053] The invention essentially consists of integrating a robot with a two-axis positioner into an installation while guaranteeing inerting in the inerting enclosure in which the laser beam is used for manufacturing, with very low O2 and H2O values. The advantages of the invention are numerous, including:

[0054] - the possibility of moving a cutting, welding, cladding or additive manufacturing laser head in the three directions X, Y, Z, while guaranteeing the sealing of the entire inerting enclosure and therefore constant inerting;

[0055] - the possibility of producing parts of specific large dimensions and / or complex three-dimensional shapes, in particular elliptical revolution shapes or with added functions on cylindrical shapes, thanks to the two-axis positioner;

[0056] - the possibility of exiting manufactured parts through one of the airlocks through a rigid wall of the enclosure, thus allowing large volumes of gas to be recycled in the latter;

[0057] - an improvement in the quality of welds and parts produced using cutting processes, or laser beam welding and laser metal additive manufacturing;

[0058] - ease of use and adaptability to multiple processes with all types of industrial robots available, by standardizing all the parts, flanges, joints, mechanisms which may be necessary for the operation of an installation according to the invention;

[0059] - easy and quick disassembly, typically around 15 minutes, in the event of a change of environment, tools or simply for changing the flexible sealing skirt in the event of deterioration. This advantage is essential for the industry which is constrained by high immobilization costs;

[0060] The potential applications of the invention described are that its installation can be carried out on all types of initially rigid hermetic inerting enclosures / chambers existing.

[0061] All industrial applications of laser welding and additive manufacturing are concerned, particularly nuclear, aeronautical, naval and automotive.

[0062] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures. Brief description of the drawings

[0063] [Fig 1] Figure 1 is a perspective view of a state-of-the-art hermetic inerting enclosure.

[0064] [Fig 2] Figure 2 is a perspective view of a metal additive manufacturing installation by laser, with a hermetic inerting enclosure and an articulated arm robot according to the invention.

[0065] [Fig 3] Figure 3 is a partial cross-sectional view of an installation according to Figure 2.

[0066] [Fig 4A], [Fig 4B] Figures 4A and 4B are perspective views of an end effector of the robot of the installation according to Figures 2 and 3.

[0067] [Fig 5] Figure 5 reproduces Figure 2, without the presence of the upper wall of the enclosure and the sealing skirt with the exterior.

[0068] [Fig 6] Figure 6 is a perspective view of a metal additive manufacturing installation by laser, with hermetic inerting enclosure, articulated arm robot and two-axis positioner according to the invention.

[0069] [Fig 7] Figure 7 is another perspective view of the installation according to Figure 6.

[0070] [Fig 8] Figure 8 is a perspective view of an installation according to Figure 6 or 7, without the presence of the inerting enclosure.

[0071] [Fig 9] Figure 9 is a perspective view of a two-axis positioner according to the invention.

[0072] [Fig 10A], [Fig 10B], [Fig 10C], Figures 10A, 10B, 10C are perspective views of a two-axis positioner according to the invention, according to different pivoting positions of the workpiece support plate.

[0073] [Fig 11] Figure 11 is a cross-sectional view of a two-axis positioner according to the invention, taken at the level of the rotating part of the positioner.

[0074] Detailed description

[0075] Throughout the present application, the terms "lower", "upper", "below" and "above" are to be understood by reference to an inerting enclosure of an installation according to the invention, as it is in horizontal operating configuration.

[0076] For the sake of clarity, the same element according to the state of the art and according to the invention is designated by the same numerical reference.

[0077] Figure 1 has already been described in the preamble. It will therefore not be detailed below.

[0078] Figures 2 and 3 show a laser-based metal additive manufacturing installation 1 according to the invention.

[0079] This installation firstly comprises an inerting enclosure 10, under an inert atmosphere, housing a support, not shown, for a part to be produced by additive manufacturing. The inert atmosphere can be controlled by means of an oxygen sensor and advantageously water. The temperature within the enclosure can be controlled by means of a temperature sensor. Advantageously, the humidity within the enclosure can be controlled by means of an H2O sensor.

[0080] The inerting enclosure 10 comprises five rigid walls 11, 12, 13, 14, 15 delimiting a right parallelepiped with the exception of the upper opening to which the periphery 20 of a flexible sealing skirt 2 is fixed in a sealed manner.

[0081] The openwork central part 21 of the sealing skirt 2 is fixed in a sealed manner to a robot effector 3. More precisely, the fixing of this openwork central part 21 is carried out on a sealed fixing flange 30 of the end effector 3, of generally circular shape.

[0082] The seal between the flexible skirt 2 and the rigid walls 11, on the one hand, and the sealed fixing flange on the other hand is such that the O2 and H2O values ​​are less than 10 ppm within the inerting enclosure.

[0083] The flexible skirt 2 is resistant to high temperatures, ensuring the tightness of the inerting enclosure. The skirt 2 may be made of a flexible polymer to give the robot arm sufficient degrees of freedom so that it can bring the end effector 3 to any location inside the inerting enclosure. The seals forming the seal between the skirt 2 and the rigid part of the enclosure and between the skirt 2 and the end effector 3 are preferably made of nitrile. This robot effector 3 comprises a support 31 for the head of a laser 5 adapted to emit a cutting, welding or additive manufacturing beam, and fixed or made integrally with the fixing flange 30.

[0084] A robot 4 with an articulated arm 40, preferably with six axes, is arranged with its base 41 near the inerting enclosure 10.

[0085] The end effector 3 is attached to the end wrist 42 of the robot 4.

[0086] Thus, the robot 4 allows movement of the end effector 3 and therefore of the laser head 5 in one and / or the other of the three orthogonal directions (X, Y, Z) inside the enclosure. The flexible skirt 2, as fixed, deforms while ensuring sealing during the movements of the robot 4 and of the end effector 3 fixed thereto.

[0087] End effector 3 is shown in more detail in Figures 4A and 4B.

[0088] The support 31 integrates a fixing flange 32 to the robot end wrist 42.

[0089] The sealed flange 30 for attachment to the skirt 2 houses a sealed passage 33 for cable(s) or fiber(s) for supplying the laser, for electrical supply, for supplying fluids, in particular the inerting gas, for control and / or instrumentation cables. This sealed flange 30 may be a standard, standardized flange. The sealed flange 30 comprises a set of sealed cable passages for bringing to the end effector 3 all the elements essential for its proper operation, such as for example: the optical fiber, the filler wire, the gas supplies, etc. This flange also makes it possible to bring to the end effector sensors for monitoring the ambient conditions of the inerting enclosure such as O2 and H2O sensors. The sealed cable passage 33 may allow cables for instrumentation such as thermal sensors to be passed.

[0090] This sealed fixing flange 30 can also accommodate a sealed passage 35 for a wire reel 6 to be melted by the laser for welding or additive manufacturing, the reel being fixed to the support 31 of the end effector 3.

[0091] The laser source 5 is controlled by a transmission signal sent from a control bay of the robot to the laser source. The gases in the head are managed by an upstream box which is not shown.

[0092] The laser beam 5 is supported by the support so that the axis of the beam it emits is centered on the center of the sealed fixing flange 30. In addition, one or more instrumentation supports 36, for example Oi and / or H2O or temperature and / or pressure sensors, can be fixed in the lower part of the support 31 to instrument the interior of the inerting enclosure 10. In general, the supports 36 can be intended to receive instrumentation, such as cameras in the visible and infrared range in particular, pyrometers, a thermal camera, etc. These supports 36 are preferably removable and can be removed manually, without tools, from the end effector 3.

[0093] Figures 6 to 7 show the integration of a two-axis positioner 7 in the rigid lower wall 15 of the inerting enclosure. One of the two axes is an axis of rotation around the Z direction and one is an axis of pivoting around another (Z) of the three directions, to respectively rotate and pivot, inside the enclosure, at least the upper plate around which the second flexible sealing skirt is fixed in a sealed manner, the upper plate forming a support for a part to be produced by cutting, welding, reloading or additive manufacturing.

[0094] This positioner 7 comprises an upper plate 70 forming a support for a part to be produced by cutting, welding, recharging or additive manufacturing by the laser 5.

[0095] The upper plate 70 is rotatably mounted on itself and fixed to a body 72 pivoting relative to the base 71 of the positioner 71.

[0096] A flexible sealing skirt 8 ensures sealing between the rotating upper plate 70 and the rigid lower wall 15 of the inerting enclosure 10.

[0097] More precisely, the periphery 80 of the flexible sealing skirt 8 is fixed in a sealed manner to the rigid lower wall 15 while the openwork central part 81 of the skirt 8 is fixed in a sealed manner around the rotary plate 70 of the positioner 7.

[0098] The seal between the flexible skirt 8 and the rigid wall 15 on the one hand, and around the lower rotating plate 70 on the other hand, is such that the O2 and H2O values ​​are less than 10 ppm within the inerting enclosure.

[0099] Like the flexible skirt 2, the flexible skirt 8 resists high temperatures while ensuring the sealing of the inerting enclosure. The fixing of the sealed flexible skirt 8 around the upper rotating plate 70 of the positioner can be ensured by constituting a pre-assembled sub-assembly before its installation in the inerting enclosure, as shown in Figure 9.

[0100] The upper rotary table 70 can take different tilt / pivot positions, for example horizontal (Figure 10A), +20° from horizontal (Figure 10B), or -20° from horizontal (Figure 10C).

[0101] Figure 11 shows an advantageous variant embodiment of the positioner 7 according to the invention.

[0102] The upper plate 70 and a lower plate 73 are integral with each other and fixed on the rotation axis. Preferably, the lower rotary plate 73 is rotatably mounted with contact with a pivot body 72 (ring), fixed on the pivot axis.

[0103] The upper plate 70 and the lower plate 73, which connects to the 2-axis positioner, can rotate freely while being driven by the 2-axis positioner, without the body 72 on which the connections are installed rotating.

[0104] At least one seal 74, preferably two, arranged at the periphery, define(s) a sealed space between the two rotary plates 70, 73.

[0105] A cooling plate 75 is mounted in the sealed space. Inside this plate 75 a heat transfer fluid can circulate so as to cool the upper plate 70.

[0106] A locking pin 77, arranged on the periphery, makes it possible to block the pivoting of the body 72 relative to the base 71 of the positioner.

[0107] The installation 1 which has just been described makes it possible to quickly produce large parts and / or parts with complex shapes, particularly three-dimensional ones, such as elliptical revolution shapes, in an inert environment with very low Oi and / or H2O values, which guarantees the quality of the fusion bath by the laser.

[0108] The invention is not limited to the examples which have just been described; in particular, it is possible to combine characteristics of the illustrated examples within non-illustrated variants.

[0109] Other variants and embodiments may be envisaged without departing from the scope of the invention. For example, if in the illustrated example, the robot implemented is an articulated arm robot, other types of robot may be envisaged, such as a Cartesian robot.

[0110] Also, if in the example illustrated, the inerting enclosure is in the shape of a right parallelepiped, any other rigid shape can be considered which allows a sealed fixing of a flexible skirt which ensures the sealing interface with the end of a robot and guarantees an inert environment with very low Oi and / or H2O values.

Claims

Claims 1. Installation (1) for cutting, welding, cladding or additive manufacturing by laser beam, comprising: - an inerting enclosure, under an inert atmosphere, delimited by at least one rigid wall and a first and a second flexible sealing skirt each fixed in a sealed manner to the at least one rigid wall; - a robot end effector comprising a support at least a part, preferably its head, of at least one laser adapted to emit a cutting, welding, recharging or additive manufacturing beam and at least one sealed fixing flange, fixed or made integrally with the support and on which the first flexible sealing skirt is fixed in a sealed manner; - a robot to which the robot end effector is attached, the robot being adapted to allow movement of the end effector inside the enclosure, in one and / or the other of the three orthogonal directions (X, Y, Z); - a positioner with plate(s), with two axes, including an axis of rotation around one (Z) of the three directions and an axis of pivoting around another (Z) of the three directions, to respectively rotate and pivot, inside the enclosure, at least the upper plate around which the second flexible sealing skirt is fixed in a sealed manner, the upper plate forming a support for a part to be produced by cutting, welding or additive manufacturing.

2. Installation (1) according to claim 1, the enclosure comprising five rigid walls delimiting a right parallelepiped with the exception of the upper opening to which the first flexible skirt is fixed in a sealed manner.

3. Installation (1) according to claim 1 or 2, the robot being a six-axis articulated arm robot.

4. Installation (1) according to one of the preceding claims, the positioner comprising a locking pin to limit the pivoting of the upper plate, preferably at an angle of at most + / - 20° relative to the horizontal.

5. Installation (1) according to one of the preceding claims, the sealed fixing flange housing at least one sealed passage for the laser power cable(s) or fiber(s), power supply, fluid supply, in particular inerting gas, control and / or instrumentation cable(s).

6. Installation (1) according to claim 5, the sealed fixing flange further housing a sealed passage for a wire reel to be melted by the laser for welding or additive manufacturing, the reel being fixed to the support of the end effector.

7. Installation (1) according to one of the preceding claims, the waterproof fixing flange being of generally circular shape, the periphery of which is fixed in a waterproof manner to the flexible skirt.

8. Installation (1) according to claim 7, the laser being supported so that the axis of the beam which it emits is centered on the center of the waterproof fixing flange.

9. Installation (1) according to one of the preceding claims, comprising at least one control unit for controlling the laser, the supply of the inerting gas and the movement of the robot and thereby of the end effector in the enclosure.

10. Installation (1) according to one of the preceding claims, the seal between the first flexible skirt and the rigid wall(s) on the one hand, and the sealed fixing flange on the other hand being such that the O2 and H2O values ​​are less than 10 ppm within the inerting enclosure.

11. Use of the installation (1) according to one of the preceding claims, for the production by cutting, welding or additive manufacturing by laser of parts intended for the nuclear, aeronautical, naval or automotive industries.

Images