WO2024246188A1 - Equipment for cutting, welding, recharging or metal additive manufacturing by laser beam, comprising an inerting chamber and a robot, the end effector of which is housed in the chamber - Google Patents

Abstract

The invention relates to equipment (1) for cutting, welding, recharging or additive manufacturing by laser beam, incorporating a robotized mechanism (4) while ensuring inerting in the inerting chamber (10) in which the laser beam is used for manufacturing, with very low O2 and H ₂O values.

Description

Description

Title of the invention: Installation for cutting, welding, reloading or metal additive manufacturing by laser beam comprising an inerting enclosure and a robot whose end effector is housed in the enclosure.

Technical field

[0001] The present invention mainly relates to the field of metal additive manufacturing.

[0002] More particularly, the invention relates to an improvement by robotization of an additive manufacturing process using a laser beam within an inerting enclosure.

[0003] 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, resurfacing, metal additive manufacturing, by laser beam in all industrial, engineering and part manufacturing fields, particularly in the nuclear field.

Previous technique

[0004] The WLAM process is a relatively recent process under development. Such a process makes it possible to design parts or shapes from a drawing software. A part is produced in layers so as to obtain the thinnest possible layers. The layers are then deposited successively 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.

[0005] Compared to selective laser melting (SLM) and laser powder deposition (LMD) technologies, 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 thus makes it possible to build parts that could not be built with a wire arc additive manufacturing (WAAM) process.

[0006] In addition, the use of wire guarantees a material yield of 100%. [0007] Furthermore, in a WLAM process, the risks associated with the use of a powder are eliminated. A WLAM process thus allows a significant reduction in costs associated with personal protective equipment and health monitoring of operators.

[0008] Despite all the above advantages, the level of technological maturity of a WLAM process is lower than for the WAAM process.

[0009] Generally speaking, laser welding and metal additive manufacturing processes differ primarily from arc processes such as TIG welding, or MIG welding, in that they are performed at higher welding speeds, higher power densities, and higher melting temperatures.

[0010] This involves significant temperature gradients around the weld pool, causing, by convection, polluted gas around the weld pool. This generates impurities which are detrimental to the technical performance of the parts produced: appearance of cracks, crevices, bubbles, impurities, etc.

[0011] In particular, it is noted in the case of a WLAM process that the solutions usually used to carry out inerting do not make it possible to limit the defects mentioned above. It is recalled 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 makes it possible to control the atmosphere during the additive printing process.

[0012] Current inerting requires spraying very large quantities of gas for mixed results. In addition, the neutral gas (argon, nitrogen) used is lost by dispersing into the atmosphere.

[0013] Furthermore, the quality criteria required in certain fields of application, such as that of low-carbon energies (nuclear or not), require the absence of defects in the parts produced, sometimes manufactured in special alloys. This implies inerting near the molten pool with very low values of O ₂ and H ₂ O, typically less than 10 ppm.

[0014] However, to date, these values can only be obtained in a hermetic inerting enclosure which is rigid, that is to say with walls which delimit it which are rigid.

[0015] [Eig.l] shows such a rigid enclosure 10 according to the state of the art, with a general rectangular parallelepiped shape: it is delimited by four side walls 11, 12, 13, 14, a lower wall 15, and an upper wall 16. In order to be able to easily move the enclosure, it can be provided with feet on casters 17. Portholes 18 are intended to receive gloves, not shown, for handling parts, tools, fabrications, and to allow maintenance to be carried out on the head of the fa- additive building. 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.

[0016] Furthermore, robotization of cutting, welding, reloading or laser additive manufacturing installations would make it possible to ensure large movements in three dimensions and thus make it possible to quickly produce finished metal volume parts with complex geometries.

[0017] Inerting enclosures are known that include a robot inside them. The inerting volume is then significantly larger, making the inerting of the enclosure longer and more expensive.

[0018] There is therefore a need to improve cutting, welding 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 in order to best comply with the standards in force.

[0019] The aim of the invention is to respond at least in part to this need.

Disclosure of the invention

[0020] To do this, the invention relates, in one of its aspects, to an installation for cutting, welding, reloading or additive manufacturing by laser beam, comprising

[0021] - an inerting enclosure, under an inert atmosphere, housing a support for a part to be produced by cutting, welding, reloading or additive manufacturing, the inerting enclosure being delimited by at least one rigid wall and a flexible sealing skirt fixed in a sealed manner to at least one rigid wall;

[0022] - a robot end effector comprising a support at least one part, preferably its head, of at least one laser adapted to emit a cutting, welding or additive manufacturing beam and at least one sealed fixing flange, fixed or made integrally with the support and on which the flexible sealing skirt is fixed in a sealed manner;

[0023] - 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).

[0024] The inerting gas to be injected can be argon or nitrogen.

[0025] 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 flexible skirt is fixed in a sealed manner.

[0026] Advantageously, the robot is a six-axis articulated arm robot. [0027] According to an advantageous variant embodiment, 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).

[0028] According to this variant, the sealed fixing flange also houses 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.

[0029] Preferably, the waterproof fixing flange is of generally circular shape, the periphery of which is fixed in a waterproof manner to the flexible skirt.

[0030] 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.

[0031] According to another advantageous embodiment, the installation comprises at least one control-command unit for controlling at least the laser, the supply of the inerting gas and preferably the movement of the robot and thereby of the end effector in the enclosure.

[0032] In an advantageous configuration, the seal between the 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.

[0033] Cutting, welding and additive manufacturing processes using a laser according to the state of the art make it possible to achieve high working speeds at high temperatures.

[0034] On the other hand, it has been found that these processes generate more or less pollution, in particular dust and/or smoke from the fusion bath generated by the laser, depending on the materials melted.

[0035] 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.

[0036] However, the quality criteria required in certain areas require the absence of defects in the parts produced, sometimes manufactured in special alloys.

[0037] This necessarily implies that the production of these parts is done with inerting near the fusion bath with very low values, in O ₂ and H ₂ O, typically less than 10 ppm.

[0038] To date, these values can only be obtained in a rigid hermetic inerting enclosure.

[0039] Furthermore, the robotization of current laser welding and additive manufacturing installations guarantees large three-dimensional movements and thus makes it possible to quickly produce finished metal volume parts with complex geometries. [0040] The invention essentially consists of integrating robotization 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.

[0041] The advantages of the invention are numerous, among which we can cite:

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

- the possibility of producing parts of specific large dimensions and/or complex shapes;

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

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

- 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

- 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;

[0042] 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.

[0043] All industrial applications of laser welding and additive manufacturing are concerned, particularly nuclear, aeronautical, naval and automotive.

[0044] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given for illustrative and non-limiting purposes with reference to the following figures.

Brief description of the drawings

[0045] [Fig.l] [Fig.l] is a perspective view of a hermetic inerting enclosure according to the state of the art.

[0046] [Fig.2] [Fig.2] is a perspective view of an additive manufacturing facility. metallic by laser, with hermetic inerting enclosure and articulated arm robot according to the invention.

[0047] [Fig.3] [Fig.3] is a partial cross-sectional view of an installation according to [Fig.2],

[0048] [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.

[0049] [Fig.5] [Fig.5] repeats [Fig.2], without the presence of the upper wall of the enclosure and the sealing skirt with the exterior.

Detailed description

[0050] 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.

[0051] 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.

[0052] [Fig.l] has already been described in the preamble. It will therefore not be detailed below.

[0053] Figures 2 and 3 show a laser-based metal additive manufacturing installation 1 according to the invention.

[0054] This installation firstly comprises an inerting enclosure 10, under an inert atmosphere, housing a support, not shown, of a part to be produced by additive manufacturing. The inert atmosphere can be controlled by means of an oxygen sensor and advantageously in 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.

[0055] 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 is fixed in a sealed manner, the periphery 20 of a flexible sealing skirt 2.

[0056] 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.

[0057] 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.

[0058] The flexible skirt 2 resists high temperatures while ensuring the sealing of the inerting enclosure. The skirt 2 can be made of flexible polymer to give sufficient degrees of freedom to the robot arm so that it can bring the end effector in any location inside the inerting enclosure. The seals providing the seal between the skirt 2 and the rigid part of the enclosure as well as between the skirt and the end effector 3 are preferably made of nitrile.

[0059] This robot effector 3 comprises a support 31 of 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.

[0060] A robot 4 with an articulated arm 40, preferably with six axes, is arranged with its base 41 near the inerting enclosure 10.

[0061] The end effector 3 is attached to the end wrist 42 of the robot 4.

[0062] Thus, the robot 4 allows a 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 a seal during the movements of the robot 4 and of the end effector 3 fixed thereto.

[0063] The end effector 3 is shown in more detail in Figures 4A and 4B.

[0064] The support 31 integrates a fixing flange 32 to the end wrist 42 of the robot.

[0065] The sealed flange 30 for fixing to the skirt 2 houses a sealed passage 33 for the laser power supply cable(s) or fiber(s), for the electrical supply, for the supply of fluids, in particular the inerting gas, for the control and/or instrumentation cable(s). This sealed flange 30 may be a standard, standard 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 O ₂ and H ₂ O sensors. The sealed cable passage 33 may make it possible to pass cables for instrumentation such as thermal sensors. This waterproof fixing flange 30 can also accommodate a waterproof 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.

[0066] The laser source 5 is controlled by a transmission signal which is sent from a control bay of the robot to the laser source. The gas management in the head is done by an upstream box which is not shown.

[0067] 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.

[0068] Furthermore, one or more instrumentation supports 36, for example O 2 and/or H ₂ O sensors 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. Generally speaking, 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.

[0069] The installation 1 which has just been described makes it possible to rapidly produce parts of large dimensions and/or complex shapes in an inert environment with very low _O2 and/or _H2O values, which guarantees the quality of the fusion bath by the laser.

[0070] The invention is not limited to the examples which have just been described; it is possible in particular to combine characteristics of the examples illustrated within non-illustrated variants.

[0071] Other variants and embodiments can be envisaged without departing from the scope of the invention.

[0072] For example, if in the example illustrated, the robot implemented is an articulated arm robot, other types of robot can be considered, such as a Cartesian robot.

[0073] 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 values of O ₂ and/or H ₂ O.

Claims

Claims [Claim 1] Installation (1) for cutting, welding, resurfacing or additive manufacturing by laser beam, comprising: - an inerting enclosure (10), under an inert atmosphere, housing a support for a part to be produced by cutting, welding, reloading or additive manufacturing, the inerting enclosure being delimited by at least one rigid wall (11, 12, 13, 14, 15) and a flexible sealing skirt (2) fixed in a sealed manner to the at least one rigid wall; - a robot end effector (3) comprising a support (31) of at least one part, preferably its head, of at least one laser adapted to emit a cutting, welding or additive manufacturing beam and at least one sealed fixing flange (30), fixed or made integrally with the support and on which the flexible sealing skirt is fixed in a sealed manner; - a robot (4) 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). [Claim 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 flexible skirt is fixed in a sealed manner. [Claim 3] Installation (1) according to claim 1 or 2, the robot being a six-axis articulated arm robot. [Claim 4] Installation (1) according to one of the preceding claims, the sealed fixing flange housing at least one sealed passage (34) for the laser power supply cable(s) or fiber(s), for the electrical supply, for the supply of fluids, in particular the inerting gas, for the control and/or instrumentation cable(s). [Claim 5] Installation (1) according to claim 4, the sealed fixing flange further housing a sealed passage (35) 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. [Claim 6] 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. [Claim 7] Installation (1) according to claim 6, the laser being supported so that the axis of the beam which it emits is centered on the center of the sealed fixing flange. [Claim 8] Installation (1) according to one of the preceding claims, comprising at least one control-command unit (33) for controlling at least the laser, the supply of the inerting gas and preferably the movement of the robot and thereby of the end effector in the enclosure. [Claim 9] Installation (1) according to one of the preceding claims, the sealing between the 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. [Claim 10] Use of the installation according to one of the preceding claims, for the production by cutting, welding, reloading or additive manufacturing by laser of parts intended for the nuclear, aeronautical, naval or automobile industries.