Electron beam welding device

Abstract

The invention relates to an electron beam welding device (1) comprising: - a cathode (2) comprising an emitting surface (9) that emits electrons; - an anode (3) having an anode hole (4), wherein a positive voltage is applied to the anode relative to the cathode so as to create an electron beam (5) from the cathode towards the anode; - a beamforming electrode (6) comprising a flared surface arranged so as to focus the electron beam emitted between the cathode and the anode, characterised in that a portion (8) of the flared surface of the beamforming electrode (6) extends behind the emitting surface (9) of the cathode in the direction of emission of the electron beam.

Description

Electron beam welding device

[0001] The present invention relates to an electron beam welding device, in particular for operation in space.

[0002] Welding is a process for joining elements. In space, under vacuum conditions, structures are most often assembled by mechanical docking interfaces such as latches.

[0003] However, welding may be considered for the future construction of structures in space. Most welding methods used for terrestrial construction are arc welding. However, in vacuum conditions, it is difficult to generate and maintain a stable arc discharge. Arc welding also requires the supply of a consumable such as ionized gas, which is a major drawback for use in space.

[0004] An alternative to arc welding is laser welding. However, this method has a relatively low energy efficiency. Some of the energy is dissipated as heat. Furthermore, some materials reflect some of the laser, reducing energy efficiency and creating potential hazards for a spacecraft.

[0005] Electron beam welding is known as a method used on Earth in artificial vacuum conditions, given the presence of the atmosphere. Electron beam welding also has higher joint quality and mechanical properties than arc or laser welding.

[0006] Emitting an electron beam requires heating a cathode above its working temperature, and creating a high voltage between an anode and this cathode. The free electrons generated by heating the cathode are then accelerated by the electrical potential difference, the electron beam is shaped by a beam-forming electrode and then focused by a focusing coil, in order to converge the electron beam at an area to be welded.

[0007] The surface power produced by the welding device, allowing the material to be melted, is therefore notably dependent on the voltage between the anode and the cathode, the distance between these elements, the heating temperature of the cathode as well as the focusing of the electron beam.

[0008] Using high voltage is a source of constraints. It requires the use of heavy and bulky voltage sources and / or converters. In addition, high voltage requires spacing or insulation of the electron beam components to prevent the creation of electric arcs.

[0009] Additionally, high accelerating voltage generates X-rays during welding that can potentially damage nearby spacecraft.

[0010] In the case of use in orbit, the weight and size of the welding system are decisive criteria for the viability of this method.

[0011] The use of welding also requires the management of contamination created during the operation, such as welding ejecta or metal fumes.

[0012] This is the case, for example, when using arc or laser welding, or electron beam welding.

[0013] For use in space, the issue of collecting solder ejecta is crucial, because uncollected ejecta could become space debris dangerous for the host system and all space vehicles.

[0014] Furthermore, metal vapors generated in the weld pool can interfere with the energy beam, altering the quality of the welding and generating defects in the assembly of the elements, or even deposit on critical surfaces of the satellite, rendering it inoperable.

[0015] The invention therefore relates to a welding device improving the power of the electron beam, thus making it possible to reduce the voltage used, and therefore the weight and size of the welding device.

[0016] The invention also aims to propose a solution to be able to limit contamination of the external environment during the welding process.

[0017] The invention relates to an electron beam welding device comprising:a cathode comprising an emitting surface emitting electrons,an anode with an anode hole, to which a positive voltage is applied relative to the cathode so as to create an electron beam from the cathode to the anode,a beam-forming electrode, called a Wehnelt electrode, comprising a flared surface and arranged to shape and in particular focus the electron beam emitted between the cathode and the anode,characterized in that a portion of the flared surface of the beam-forming electrode extends behind the emitting surface of the cathode in the direction of emission of the electron beam.

[0018] The invention comprises at least one of the following features, taken independently or in combination:

[0019] The electron beam welding device is arranged for use in space, under vacuum conditions.

[0020] The electron beam welding device is particularly suitable for assembling structures in space.

[0021] The emitting surface of the cathode defines a principal axis of emission, this axis being normal to the emitting surface at the center of the emitting surface, and crossing the emitting surface at its center.

[0022] We also define a direction of emission of the electron beam.

[0023] The anode is placed after the emitting surface in the direction of emission of the electron beam, and has an anode hole for the beam to pass through.

[0024] In the case where the emitting surface of the cathode is flat, it defines an emission plane.

[0025] In the case where the emitting surface is curved, in particular conical or curved, we define a set of emission planes comprising all the planes normal to the main emission axis intersecting the emitting surface.

[0026] The cathode, anode and beam-forming electrode are parts of revolution having as their axis the principal emission axis of the electron beam.

[0027] A start position of the flared surface and an end position of the flared surface are defined on the main emission axis.

[0028] The flared surface therefore extends between a starting plane of the flared surface and an ending plane of the flared surface, these planes being parallel to each other and normal to the main emission axis.

[0029] In the case of a planar emitting surface, the term: "a portion of the flared surface of the beam-forming electrode extends behind the emitting surface of the cathode in the direction of emission of the electron beam" means that the emission plane is placed between the start plane of the flared surface and an end plane of the flared surface.

[0030] In the case of a curved emitting surface, the term: "a portion of the flared surface of the beam-forming electrode extends behind the emitting surface of the cathode in the direction of emission of the electron beam" means that at least one emission plane is placed between the start plane of the flared surface and an end plane of the flared surface.

[0031] The beam-forming electrode assembly includes at least a portion of a flared surface extending behind the emitting surface of the cathode in the direction of emission of the electron beam.

[0032] In particular, in the case of a curved emitting surface, all of the emitting planes of the emitting surface are placed between the start plane of the flared surface and an end plane of the flared surface.

[0033] The beamforming electrode includes a cavity in which the cathode is placed.

[0034] The flared surface of the beamforming electrode is conical.

[0035] Alternatively, the flared surface of the beamforming electrode is concave, or domed.

[0036] In particular, the flared surface of the beam-forming electrode is a cone of half-angle α, in other words forms an angle α with the main emission axis, with α between 20° and 80°, in particular between 32.5° and 67.5°, in particular between 40° and 60°.

[0037] The voltage difference between the anode and the cathode is a voltage U1 called "low high voltage", that is to say a voltage U1 lower than 35kV, in particular lower than 30kV, in particular between 10kV and 20kV.

[0038] The anode is placed at the floating ground of the welding device, at a potential of 0V.

[0039] The workpiece to be welded is placed at the floating ground of the welding device at a potential of 0V.

[0040] The cathode is placed at a negative potential.

[0041] Thus, a voltage U1 between the anode and the cathode is obtained by placing the anode at a potential of 0V, and the cathode at a fixed potential of - U1.

[0042] The welding device comprises a focusing coil arranged to produce a magnetic field for focusing the electron beam at a working distance corresponding to the welding area.

[0043] The focusing coil is placed after the anode in the direction of emission of the electron beam, and has a hole for the beam to pass through.

[0044] The welding device comprises a casing arranged to contain the cathode, the beam-forming electrode, the anode, and optionally a focusing coil.

[0045] The envelope is cylindrical in shape.

[0046] Alternatively, the envelope can be, for example, oval or rectangular in section.

[0047] The envelope is made of metallic material.

[0048] Alternatively, the envelope is made of electrically and thermally insulating material, particularly ceramic, or a composite, electrically conductive or not.

[0049] The welding device includes a set of insulating pieces positioned between the beam forming electrode, the cathode and the shell of the welding device, and arranged to electrically insulate the beam forming electrode, the cathode and the shell.

[0050] Insulating parts are made of electrically insulating material, for example ceramic.

[0051] The welding device is arranged to be placed opposite a workpiece to be welded, so that the electron beam strikes the workpiece to be welded at a weld zone.

[0052] For example, the electron beam strikes the part to be welded perpendicular to its surface at a welding zone.

[0053] The welding device comprises a power supply unit comprising:a power source, in particular a direct voltage source,at least one high voltage converter, powered by the power source and arranged to provide a high voltage power supply,at least one current converter, powered by the power source and arranged to provide a high current power supply, in particular to provide a current of intensity I greater than 1A, in particular equal to 3A,a power circuit, electrically connected to the high voltage converters and to the current converter.

[0054] The power source is a battery.

[0055] The welding device comprises two high voltage converters arranged to place the beam forming electrode and the cathode at two separate potentials.

[0056] The welding device comprises two current converters arranged to supply the focusing coil and the cathode with currents of different intensity.

[0057] The power circuit is electrically connected to the anode, and fixes the anode potential to the floating ground of the welding device.

[0058] The power circuit is electrically connected to the enclosure of the welding device, and fixes the potential of the enclosure to the floating ground of the welding device.

[0059] The power circuit is electrically connected to the workpiece, and fixes the potential of the workpiece to the floating ground of the welding device.

[0060] The power circuit is electrically connected to the cathode, and supplies the cathode with current from the power converter so as to heat the cathode.

[0061] The electrical connection of the power circuit to the cathode also fixes the cathode to a fixed potential of -U1.

[0062] Alternatively, the anode and cathode may be placed at any other determining potentials between the cathode and anode a high voltage as determined above.

[0063] The power circuit is electrically connected to the focusing coil, and is arranged to power the focusing coil.

[0064] The power circuit is electrically connected to the beam-forming electrode, and controls the potential of the beam-forming electrode.

[0065] The welding device includes a beam adjustment mechanism, allowing the current emitted by the cathode and passing through the welding device to be controlled.

[0066] The beam adjustment mechanism is the power circuit.

[0067] The power circuit is arranged to adjust the potential difference between the beam forming electrode and the cathode.

[0068] For example, the beam-forming electrode is placed at a variable potential lower than the cathode potential, in particular so as to determine between the cathode and the beam-forming electrode a voltage U2 of between 0kV and 3kV.

[0069] Adjusting the potential difference between the beam-forming electrode and the cathode shapes the electron beam, and controls the current emitted by the cathode and passing through the welding device.

[0070] Advantageously, the use of electronic control of the potential difference between the cathode and the beam-forming electrode makes it possible to control the current emitted by the cathode and passing through the welding device almost instantaneously, without consuming additional energy, and without requiring the movement of mechanical parts.

[0071] Alternatively, the beam adjustment mechanism is the current converter.

[0072] The current converter is arranged to allow adjustment of the heating current through the cathode and therefore the temperature of the emitting surface during use.

[0073] Adjusting the temperature of the emitting surface allows you to control the amount of free electrons emitted, and therefore to control the current emitted by the cathode and passing through the welding device.

[0074] Alternatively, the beam adjustment mechanism comprises at least one moving part arranged to be moved linearly along the main emission axis.

[0075] The anode, cathode, and / or beam-forming electrode are placed on a moving part, and the moving parts are arranged to control the relative positions of the beam-forming electrode, cathode, and anode during use of the welding device.

[0076] Adjusting the relative positions of the beam-forming electrode, cathode, and anode during operation of the welding device allows control of the shaping of the electron beam, and thus control of the current emitted by the cathode and passing through the welding device.

[0077] The use of a flared surface extending behind the cathode emitting surface allows for better electron extraction and electron beam shaping for a given electron beam accelerating voltage.

[0078] Thus, the use of a flared surface extending behind the emitting surface of the cathode allows the improvement of the performance of the welding device, even for acceleration voltages significantly lower than the state of the art, in particular for acceleration voltages lower than 35kV.

[0079] In addition, the insulation distance to prevent discharge inside the electron gun housing can be reduced, so the size of the welding device can be reduced.

[0080] The emissive surface of the cathode is made of a material with a low work function and is resistant to high temperatures. For example, the cathode is made of tungsten.

[0081] Alternatively, the cathode is made of Lanthanum Hexaboride (LaB6).

[0082] The beam forming electrode is made of non-ferromagnetic metal alloy.

[0083] For example, the beam forming electrode is made of stainless steel, or aluminum.

[0084] The anode is made of a non-ferromagnetic metal alloy.

[0085] For example, the anode is made of stainless steel or aluminum.

[0086] The cathode and the anode are separated by a first isolation distance D1 along the main emission axis of the electron beam, this isolation distance D1 being between 3mm and 15mm.

[0087] The minimum distance D2 is defined along the main emission axis between the start plane of the flared surface and the emission plane of the emitting surface closest to the start plane of the flared surface.

[0088] This distance D2 is between 0.001mm and 0.5mm, in particular is equal to 0.5mm.

[0089] The distance along the main emission axis between the start plane of the flared surface and the emission plane of the emitting surface closest to the start plane of the flared surface can be mechanically adjusted by linear translation of the cathode or beam-forming electrode along the main emission axis.

[0090] The invention also relates, independently or in combination with the above, to a welding device arranged to carry out welding together of at least two parts to be welded, the welding device comprising:a welding unit arranged to carry out welding along the junction of two parts to be welded, generating a weld pool at a welding zone,an anti-contamination hood arranged to be placed, in particular mobile, in contact with the parts to be welded so that the welding unit and the anti-contamination hood encompass the entire weld pool and that any half-line starting from the weld pool intersects either the anti-contamination hood or the welding unit,the welding device being in particular arranged to move the weld zone relative to the parts to be welded during welding.

[0091] The invention comprises at least one of the following features, taken independently or in combination:

[0092] The welding device is arranged to perform welding between them of at least two parts to be welded dynamically, i.e. in such a way that the welding zone moves along the junction between the parts to be welded during welding.

[0093] An ejecta that is expelled from the weld pool and follows a straight line trajectory is stopped by the anti-contamination hood or the welding unit or the parts to be welded. Thus the ejecta cannot exit in a straight line from the volume defined by the hood, the welding unit and the parts to be welded.

[0094] A main axis of the welding unit is defined.

[0095] The main axis of the welding unit is for example:in the case of arc welding, the main axis of the welding electrode,in the case of laser welding, the main axis of the laser beam,in the case of electron beam welding, the main axis of the electron beam;

[0096] At any time during welding, the intersection between the main axis of the welding unit and the surface of at least one part to be welded is called the weld zone.

[0097] At each instant of the weld, the working distance is defined as the distance between the welding unit and the parts to be welded along the main axis of the welding unit, i.e. the distance between the welding unit and the weld zone along the main axis of the welding unit.

[0098] At each instant of the weld, α is the angle formed between the main axis of the welding unit and the parts to be welded.

[0099] In particular, the angle α is defined as the angle between the main axis of the welding unit and the plane tangent to the surface of the parts to be welded at the welding zone.

[0100] The welding unit is an electron beam gun, arranged to cause fusion of the parts to be welded by the emission of an electron beam striking the surface of the parts to be welded at the weld zone.

[0101] Alternatively, the welding unit may be a resistance welding device, or an arc welding device, or a laser welding device.

[0102] The welding device is arranged for use in space, under vacuum conditions.

[0103] The welding device is particularly arranged for the assembly of structures in space.

[0104] The welding unit is arranged to perform a weld generating a weld pool at the weld area.

[0105] The parts to be welded are flat.

[0106] Alternatively, the parts to be welded can be of any other shape, including curved or tubular.

[0107] The anti-contamination hood is maintained in contact with at least one workpiece during at least a portion of the weld.

[0108] In particular, the anti-contamination hood is kept in contact with at least one part to be welded throughout the entire weld.

[0109] The welding unit and the anti-contamination hood encompass the entire weld pool without encompassing all of the parts to be welded.

[0110] The anti-contamination hood is made of a single piece.

[0111] Alternatively, the anti-contamination hood is made up of several parts attached to each other, these different parts being able to be made of different materials.

[0112] The anti-contamination hood comprises at least one part made of heat-resistant material, for example stainless steel.

[0113] The anti-contamination hood comprises at least one part made of flexible material, for example a polymer.

[0114] Advantageously, the use of a flexible material allows the anti-contamination cover to be kept in contact with a non-smooth surface.

[0115] The anti-contamination hood includes: an anti-contamination skirt, an anti-contamination envelope.

[0116] The anti-contamination envelope is tubular in shape.

[0117] Alternatively, the envelope may be of any other shape, including conical or domed.

[0118] The anti-contamination skirt comprises at least one part made of flexible material.

[0119] The flexible material part is made of polymers.

[0120] The flexible material part is made of metal, and is arranged to be able to be deformed in contact with the parts to be welded.

[0121] The flexible material part is a comb or metal brush.

[0122] In particular, the anti-contamination skirt is made of a flexible material with a low coefficient of friction, for example polymers.

[0123] The anti-contamination jacket is attached to the welding unit.

[0124] The anti-contamination skirt is attached to the anti-contamination envelope to form the anti-contamination hood.

[0125] The anti-contamination envelope and the welding unit and the anti-contamination skirt are irreversibly assembled.

[0126] Alternatively, the welding unit, the anti-contamination shroud and / or the anti-contamination skirt are assembled in a reversible manner, so as to allow replacement of the anti-contamination skirt and / or the anti-contamination shroud without damaging the parts.

[0127] The anti-contamination skirt consists of two superimposed walls with a space between them.

[0128] The walls of the anti-contamination skirt have a substantially conical truncated shape, the large base of which is opposite the parts to be welded.

[0129] The anti-contamination hood is hermetic, i.e. it forms a hermetically sealed space with the parts to be welded and the welding unit.

[0130] The welding device comprises a vacuum pump connected to the hermetically sealed space formed by the anti-contamination hood and the parts to be welded, and arranged for the evacuation of metal vapors.

[0131] Alternatively, the anti-contamination hood has at least one orifice arranged for the evacuation of welding fumes.

[0132] Advantageously, the use of an anti-contamination hood comprising at least one orifice makes it possible to avoid an accumulation of metallic vapors inside the anti-contamination hood.

[0133] The anti-contamination hood comprises at least one part made of a porous material.

[0134] The anti-contamination envelope is made of a porous material.

[0135] For example, the anti-contamination envelope includes a metal foam or a lattice structure.

[0136] Alternatively, the anti-contamination envelope comprises a plurality of porous layers, for example by a plurality of perforated plates.

[0137] The use of a porous material prevents the accumulation of metal vapors inside the anti-contamination hood.

[0138] The anti-contamination hood has at least one drainage channel.

[0139] The drain channels are internal channels, and extend inside the anti-contamination hood.

[0140] The exhaust channels have one end placed close to the weld pool generated by the welding unit, and one end connected to an orifice in the anti-contamination hood.

[0141] The exhaust channels are arranged for the circulation of welding fumes from the welding bath to the outside of the anti-contamination hood.

[0142] The exhaust channels have one end placed close to the solder bath generated by the soldering unit, and one end connected to the vacuum pump by a suction channel, and are arranged for the circulation of solder vapors from the solder bath to the vacuum pump.

[0143] The anti-contamination hood has a protective shield.

[0144] The protective shield is arranged inside the anti-contamination hood.

[0145] The protective shield is placed around the main axis of the welding unit, and is arranged to limit the presence of welding ejecta and welding fumes along the main axis of the welding unit.

[0146] In particular, the protective shield is arranged to minimize, in a plane normal to the main axis of the welding unit, the passage surface that ejecta emitted by the weld pool and moving in a straight line could cross to reach the welding unit.

[0147] This passage surface minimized by the protective shield also influences the flow of metal vapors which can propagate along the main axis of the welding unit and can disrupt the welding.

[0148] In the case of laser welding or electron beam welding, the protective shield thus advantageously limits the disruption of the beam by vapors or ejecta which could alter the quality of the weld.

[0149] The protective shield is tubular in shape.

[0150] Alternatively, the protective shield is flat in shape, and forms a perforated disc allowing the passage of an electron beam or a laser along the main axis of the welding unit.

[0151] Alternatively, the protective shield has a layered structure.

[0152] Drainage channels are formed between the layers of the protective shield.

[0153] Alternatively, the drainage channels are tubular in shape.

[0154] The drainage channels are formed between the walls of the anti-contamination skirt.

[0155] The drainage channels have a revolution shape.

[0156] The protective shield can be formed as a single unit with the anti-contamination envelope.

[0157] Alternatively, the protective shield and the anti-contamination envelope can be two separate parts.

[0158] The evacuation channels are formed as a unit with the anti-contamination envelope or with the protective shield.

[0159] Alternatively, the drain channels are separate parts.

[0160] The anti-contamination hood includes a welding fume capture area.

[0161] The welding fume capture area is curved, in particular a dome.

[0162] The welding fume capture zone can be formed by the anti-contamination skirt, by the anti-contamination envelope, by an exhaust channel or by the protective shield.

[0163] The welding vapor capture zone is placed vertically above the welding zone, i.e. opposite the surface of the parts to be welded.

[0164] The welding fume capture area is arranged to allow condensation of welding fumes on the walls of the anti-contamination hood.

[0165] Welding creates a pressure differential, with high pressure near the weld pool, and a negative gradient away from the weld pool. This pressure differential causes the welding vapors to move from the weld pool to at least one of the holes arranged for the evacuation of welding vapors, and possibly to the vacuum pump through a suction channel.

[0166] The welding fume capture area and exhaust channels are arranged to increase the circulation time of welding fumes within the anti-contamination hood, so as to allow cooling and condensation of welding fumes on the surfaces of the anti-contamination hood, so as to limit the amount of metal fumes ejected from the anti-contamination hood.

[0167] According to one embodiment of the invention, the welding device is arranged to move opposite the parts to be welded during welding.

[0168] In particular, the welding device is arranged to move laterally opposite the parts to be welded during welding.

[0169] Thus, the movement of the welding zone along the junction between the parts to be welded is achieved by moving the welding device opposite the parts to be welded.

[0170] The main axis of the welding unit maintains a constant orientation relative to the welding device, in particular relative to the welding unit, during welding.

[0171] The main axis of the welding unit maintains a constant orientation relative to the parts to be welded during welding.

[0172] At each instant of the movement, a so-called "transverse" component of the movement is defined as the component of the movement which varies the position of the welding zone on the parts to be welded, while keeping the working distance and the angle α formed between the main axis of the welding unit and the surface of the parts to be welded fixed.

[0173] The welding device is arranged to be set in motion during welding, this movement comprising a non-zero transverse component.

[0174] Thus, the anti-contamination hood moves laterally in contact with at least one part to be welded.

[0175] The angle α formed between the main axis of the welding unit and the parts to be welded remains substantially constant during the movement of the welding device.

[0176] The angle α remains included during the entire movement of the welding device during welding in an interval [α0 - Δ, α0 + Δ], with α0 a reference angle between the main axis of the welding unit and the parts to be welded, and Δ representing a maximum deviation from this angle.

[0177] According to one aspect of the invention, Δ is less than 10°, in particular less than 3°.

[0178] Advantageously, limiting the maximum deviation from a reference angle α0 makes it possible to guarantee uniform welding during the welding process, in particular over the entire movement of the welding device.

[0179] According to one aspect of the invention, α0 is equal to 90°.

[0180] Alternatively, the welding device is arranged to be placed inclined relative to the parts to be welded, and the reference angle α0 is between 0° and 90°, in particular between 20° and 70°, in particular between 40° and 50°, in particular equal to 45°.

[0181] The welding device is tilted so that the welding area is placed behind the welding unit in the direction of movement of the welding device.

[0182] According to another embodiment of the invention, the welding unit comprises an orientation element arranged to modify the orientation of the main axis of the welding unit relative to the welding device, in particular relative to the welding unit, during welding.

[0183] The steering element is for example:in the case of arc welding, a controllable articulation of the welding electrode,in the case of laser welding, a movable lens or mirror placed in the path of the laser beam and arranged to direct the laser beam,in the case of electron beam welding, a focusing coil placed in the path of the electron beam, and arranged to direct the electron beam,

[0184] The welding device is arranged to remain stationary relative to the parts to be welded during welding.

[0185] Thus, the displacement of the welding zone along the junction between the parts to be welded is achieved by changing the orientation of the main axis of the welding unit relative to the welding device by the orientation element.

[0186] The invention relates to a welding method carried out by a welding device as described, the welding method comprising in this order the following steps: a step of placing the welding device in contact with the parts to be welded, a step of actuating the welding unit, starting the welding and generating a weld pool, a step of moving the welding zone along the junction between the parts to be welded, a step of stopping the action of the welding unit, ending the welding, possibly, a cooling step, a step of withdrawing the welding device, comprising a step of moving the welding device away from the parts to be welded.

[0187] Alternatively, the step of moving the welding device may begin before the welding unit is put into operation and / or end after the welding unit has stopped operating or after the cooling step.

[0188] The cooling stage is a waiting stage allowing the solidification of the solder bath and the condensation of the solder vapors.

[0189] The step of moving the welding zone along the junction between the parts to be welded includes a step of lateral movement of the welding device in contact with the parts to be welded.

[0190] The step of moving the welding zone along the junction between the parts to be welded includes a step of changing the orientation of the main axis of the welding unit relative to the welding device. Detailed description

[0191] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0192] This is a schematic cross-sectional representation of the electron beam welding device according to a first embodiment of the invention.

[0193] This is a close-up, cross-sectional view of the cathode / beam-forming electrode assembly of the electron beam welding device according to a first embodiment of the invention.

[0194] This is a close-up, sectional view of the cathode / beam-forming electrode assembly of the electron beam welding device according to a second embodiment of the invention.

[0195] This is a close-up, sectional view of the cathode / beam-forming electrode assembly of the electron beam welding device according to a third embodiment of the invention.

[0196] This is a close-up, sectional view of the cathode / beam-forming electrode assembly of the electron beam welding device according to a fourth embodiment of the invention.

[0197] This is a schematic representation of a welding device according to a first embodiment of the invention.

[0198] This is a schematic representation of a welding device according to the invention placed in contact with parts to be welded of flat, curved and tubular shapes.

[0199] This is a schematic representation of a welding device according to an embodiment in which the anti-contamination hood is hermetic, and the welding device comprises a vacuum pump.

[0200] This is a schematic representation of a welding device according to another embodiment in which the anti-contamination hood comprises at least one part made of a porous material.

[0201] This is a schematic representation of a welding device according to an embodiment of the invention in which the anti-contamination hood comprises evacuation channels and a protective shield.

[0202] This is a schematic representation of a welding device according to an embodiment of the invention in which the welding device is inclined relative to the parts to be welded.

[0203] This is a front view and a top view of a welding device according to an embodiment of the invention in which the parts to be welded are tubular in shape, and the anti-contamination hood completely surrounds a tubular section of the parts to be welded.

[0204] This is a schematic representation of a welding device according to one embodiment of the invention in which the welding unit comprises an orientation element arranged to modify the orientation of the main axis of the welding unit relative to the welding device.

[0205] is a schematic representation of a welding device according to an embodiment in which the anti-contamination skirt comprises two superimposed walls with a spacing between them.

[0206] The features, variants and different embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0207] Figures 1 and 2 show an electron beam welding device 1 according to the invention. This is a close-up view showing only the cathode 2 and the beam-forming electrode 6 of the welding device, for reasons of readability.

[0208] The welding device 1 comprises a cathode 2, an anode 3, a beam forming electrode 6, and a focusing coil 20 placed in a cylindrical casing 22.

[0209] The cathode 2 comprises an emitting surface 9 emitting electrons, and this emitting surface of the cathode defines a main emission axis 15 of the electron beam 5, this axis being normal to the emitting surface at the center of the emitting surface, and crossing the emitting surface at its center. A direction of emission of the electron beam is also defined.

[0210] The cathode 2, the anode 3 and the beam forming electrode 6 are parts of revolution having as their axis the main emission axis 15 of the electron beam 5.

[0211] Cathode 2 is for example made of tungsten, or alternatively of Lanthanum Hexaboride (LaB6).

[0212] The emitting surface 9 is flat, and defines an emission plane 14.

[0213] The cathode 2 is placed in a cavity 10 of the beam forming electrode 6.

[0214] The anode 3 is placed after the emitting surface 9 in the direction of emission of the electron beam 5, and has an anode hole 4 for the passage of the beam.

[0215] Anode 3 is made of a non-ferromagnetic metal alloy, for example stainless steel or aluminum.

[0216] The focusing coil 20 is placed after the anode 3 in the direction of emission of the electron beam 5, and has a hole for the passage of the beam.

[0217] The cathode 2 and the anode 3 are separated by a first isolation distance D1 of 3 mm along the main emission axis 15 of the electron beam 5.

[0218] The beam-forming electrode 6 has a flared surface 7 arranged to shape the electron beam 5 emitted between the cathode 2 and the anode 3.

[0219] This flared surface 7 therefore extends between a start plane 18 of the flared surface 7 and an end plane 19 of the flared surface 7. These planes are parallel to each other, normal to the main emission axis 15, and placed respectively at a start position 16 of the flared surface 7 and at an end position 17 of the flared surface 7 on the main emission axis.

[0220] A portion 8 of the flared surface 7 extends behind the emitting surface 9 of the cathode 2 in the direction of emission of the electron beam 5, and the emission plane 14 is therefore placed between the start plane 18 of the flared surface 7 and the end plane 19 of the flared surface 7.

[0221] The set of beam-forming electrodes 6 comprises at least one portion 8 of a flared surface 7 extending behind the emitting surface 9 of the cathode 2 in the direction of emission of the electron beam.

[0222] The starting plane 18 of the flared surface 7 and the emission plane 14 are separated by a distance D2 of 0.5 mm along the main emission axis 15.

[0223] This distance D2 can be mechanically adjusted by linear translation of the cathode 2 or the beam-forming electrode 6 along the main emission axis 15.

[0224] The flared surface 7 of the beam-forming electrode 6 is a cone forming with the main emission axis 15 an angle α equal to 50°.

[0225] The beam forming electrode 6 is made of a non-ferromagnetic metal alloy, for example stainless steel or aluminum.

[0226] The beam forming electrode 6, the cathode 2 and the cylindrical envelope 22 are electrically insulated by a set of insulating parts 23, made of ceramic and placed between the beam forming electrode 6, the cathode 2 and the cylindrical envelope 22.

[0227] The use of a flared surface 7 extending behind the emitting surface 9 of the cathode 2 allows better extraction of the electrons and better shaping of the electron beam 5 for a given acceleration voltage of the electron beam.

[0228] This thus makes it possible to improve the performance of the welding device 1 for acceleration voltages significantly lower than the state of the art, in particular for acceleration voltages below 35kV.

[0229] In addition, the insulation distance for preventing discharge inside the electron gun housing can be reduced, so that the size of the welding device 1 can be reduced.

[0230] The welding device 1 is arranged to be placed opposite a part to be welded 30, so that the electron beam 5 strikes the part to be welded at a welding zone 21.

[0231] For example, the electron beam strikes the part to be welded perpendicular to its surface at a weld zone perpendicular to its surface.

[0232] The welding device 1 comprises a power supply unit 24, comprising: a battery 25, a high voltage converter 26 powered by the battery and providing a high voltage power supply, a current converter 27 powered by the battery and providing a high current power supply of 3A, a power circuit 28, electrically connected to the high voltage converter and the current converter.

[0233] According to an embodiment not shown, the welding device 1 comprises two high voltage converters making it possible to place the beam forming electrode and the cathode at two separate potentials.

[0234] The power circuit 28 is electrically connected to the anode 3, the casing 22 of the welding device 1 and the workpiece 30, and fixes and fixes their potential to the floating ground of the welding device.

[0235] The power circuit 28 is electrically connected to the cathode 2, and supplies it with the current from the current converter 27. This high current makes it possible to heat the cathode.

[0236] The electrical connection of the power circuit 28 to the cathode 2 fixes it for example at a potential of -12kV.

[0237] The potential difference between anode 3 and cathode 2 is therefore 12kV. This voltage could be obtained by placing anode 3 and cathode 2 at other fixed potentials.

[0238] The power circuit 28 supplies the focusing coil 20, which produces a magnetic field enabling the electron beam 5 to be focused onto the welding zone 21.

[0239] In this embodiment, the power circuit 28 is an adjustment mechanism for controlling the current emitted by the cathode and passing through the welding device 1.

[0240] The power circuit 28 is electrically connected to the beam forming electrode 6, and controls the potential of the beam forming electrode 6 to adjust the potential difference between the beam forming electrode 6 and the cathode 2.

[0241] For example, the power circuit 28 places the beam-forming electrode 6 at a potential lower than the potential of the cathode, determining between the cathode and the beam-forming electrode a voltage U2 of between 0kV and 3kV.

[0242] The use of electronic control of the potential difference between the cathode 2 and the beam forming electrode 6 makes it possible to control the current emitted by the cathode and passing through the welding device 1 almost instantaneously, without consuming additional energy, and without requiring the movement of mechanical parts.

[0243] In an embodiment not shown, the beam adjustment mechanism is the high current converter 27, which is then arranged to allow adjustment of the heating current passing through the cathode 2 and therefore the temperature of the emitting surface 9 and thus control the quantity of free electrons emitted and the current of the electron beam 5.

[0244] In another embodiment not shown, the anode 3, the beam forming electrode 6 and / or the cathode 2 are placed on moving parts arranged to be moved linearly along the main emission axis 15 so as to control the relative positions of the beam forming electrode 6, the anode 3 and the cathode 2 during use of the welding device 1.

[0245] Adjusting the relative positions of the beam-forming electrode 6, the anode 3 and the cathode 2 during use of the welding device makes it possible to control the shaping of the electron beam 5, and thus to control the current emitted by the cathode and passing through the welding device 1.

[0246] This is a close-up, sectional view of the cathode 2 / beam-forming electrode 6 assembly of the electron beam welding device 1 according to a second embodiment of the invention in which the emitting surface 9 of the cathode is curved.

[0247] A set of emission planes 14a, 14b, 14c is then defined comprising all the planes normal to the main emission axis intersecting the emitting surface, and at least one emission plane of this set is placed between the start plane 18 of the flared surface 7 and the end plane 19 of the flared surface 7.

[0248] In particular, in this embodiment, all of the emission planes of the emitting surface 14a, 14b, 14c are placed between the start plane 18 of the flared surface 7 and the end plane 19 of the flared surface 7.

[0249] Figures 4 and 5 are close-up sectional views of the cathode 2 / beam-forming electrode 6 assembly of the electron beam welding device 1 according to a third and fourth embodiment of the invention, respectively, in which the flared surface 7 of the beam-forming electrode is concave or curved, respectively.

[0250] There is shown a welding device 1 according to another embodiment of the invention, placed opposite two parts to be welded 30.

[0251] The welding device 1 is arranged to carry out welding between them of the two parts to be welded 30.

[0252] The welding device 1 is arranged for use in space, under vacuum conditions, in particular for the assembly of structures in space.

[0253] The welding device comprises a welding unit 103, arranged to perform a weld along the junction 104 of the two parts to be welded 30, generating a weld pool 105 at a weld zone 21.

[0254] The welding is carried out dynamically, so that the welding zone 21 moves along the junction 104 between the parts to be welded 30 during the welding.

[0255] The welding device also comprises an anti-contamination hood 106 placed movably in contact with the parts to be welded 30 so that the welding unit and the anti-contamination hood encompass the entire weld pool 105.

[0256] Half-lines 107 from the weld pool 105 are shown on the diagram.

[0257] Any half-line starting from the weld pool 105 intersects either the anti-contamination hood 106 or the weld unit 103.

[0258] Thus, an ejecta 108 which is expelled from the weld pool 105 and which follows a straight line trajectory is stopped by the anti-contamination hood 106, the welding unit 103 or the parts to be welded 30. Thus the ejecta cannot exit in a straight line from the volume defined by the hood, the welding unit and the parts to be welded.

[0259] The welding unit 103 and the anti-contamination hood 106 encompass the entire weld pool 105 without encompassing all of the parts to be welded 30.

[0260] The welding device 1 is arranged to move laterally opposite the parts to be welded 30 during welding.

[0261] The movement of the welding device 1 opposite the parts to be welded 30 thus allows the relative movement of the welding zone 21 on the parts to be welded.

[0262] The welding unit 103 is an electron beam gun. The welding unit causes the workpieces to melt by emitting an electron beam 5 striking the surface at an external body welding zone.

[0263] A main axis 11 of the welding unit is defined as the main axis of the electron beam 5, and the welding zone 21 as the intersection between the main axis of the welding unit and the surface of the parts to be welded 30.

[0264] According to other embodiments of the invention not shown, the welding unit 103 may for example be a resistance welding device, or an arc welding device, or a laser welding device. The main axis of the welding unit may thus be for example the main axis of a welding electrode, or of a laser beam.

[0265] The welding unit 103 is arranged to perform a weld generating a weld pool 105 at the weld zone 21.

[0266] The main axis 15 of the electron beam is then, for example, the main axis of the welding electrode, or the main axis of the laser beam.

[0267] In this embodiment, the main axis 15 of the welding unit 103 maintains a constant orientation relative to the welding device 1, in particular relative to the welding unit 103, during welding.

[0268] The main axis 15 of the welding unit 103 also maintains a constant orientation relative to the parts to be welded during welding.

[0269] At each instant of the movement, the working distance 111 is defined as the distance between the welding unit 103 and the parts to be welded 30 along the main axis 15 of the welding unit, i.e. the distance between the welding unit and the welding zone 21 along the main axis 15 of the welding unit.

[0270] The main axis 15 of the welding unit 103 forms an angle α with the parts to be welded, and this angle α remains substantially constant during the movement of the welding device 1.

[0271] The angle α is defined as the angle between the main axis of the welding unit 103 and the plane tangent to the surface of the parts to be welded 30 at the welding zone.

[0272] At each instant of the movement of the welding device 1, a so-called “transverse” component 127 of the movement is defined as the component of the movement varying the position of the welding zone 21 on the parts to be welded 30, while keeping fixed the working distance 111 and the angle between the main axis 15 of the welding unit 103 and the surface of the parts to be welded 30.

[0273] The angle α remains included during the entire movement of the welding device during welding in an interval [α0 - Δ, α0 + Δ], with α0 a reference angle between the main axis 15 of the welding unit 103 and the parts to be welded 30, and Δ representing a maximum deviation from this angle.

[0274] In the embodiment shown, α0 is equal to 90°, and Δ is less than 10°, in particular less than 3°.

[0275] Advantageously, limiting the maximum deviation from a reference angle α0 makes it possible to guarantee uniform welding during the welding process, in particular over the entire movement of the welding device 1.

[0276] The welding device 1 moves laterally opposite the parts to be welded 30 during welding, that is to say is in movement during welding, this movement comprising a non-zero transverse component 127.

[0277] The anti-contamination hood 106 is kept in contact with the parts to be welded 30 during at least part of the welding, in particular during the entire welding.

[0278] Thus, the anti-contamination hood 106 moves laterally in contact with the parts to be welded 30.

[0279] The anti-contamination hood 106 is formed of several parts secured to each other, these different parts being formed of different materials.

[0280] The anti-contamination hood 106 comprises an anti-contamination skirt 116, and an anti-contamination envelope 117.

[0281] Alternatively, according to an embodiment not shown, the anti-contamination cover 106 is formed from a single piece.

[0282] The anti-contamination cover 106 comprises at least one portion of heat-resistant material 118, for example stainless steel, and at least one portion of flexible material 119, for example a polymer.

[0283] Advantageously, the use of a flexible material makes it possible to keep the anti-contamination cover 106 in contact with a non-smooth surface.

[0284] The anti-contamination envelope 117 is tubular in shape.

[0285] The anti-contamination skirt 116 is formed from a flexible material with a low coefficient of friction, for example polymers.

[0286] According to an embodiment not shown, the anti-contamination envelope 117 may be of any other shape, in particular conical or curved.

[0287] The anti-contamination jacket 117 is fixed on the welding unit, and the anti-contamination skirt 116 is fixed on the anti-contamination jacket to form the anti-contamination hood 106.

[0288] The anti-contamination envelope 117, the welding unit 103 and the anti-contamination skirt 116 are assembled irreversibly.

[0289] Alternatively, the welding unit 103, the anti-contamination jacket 117 and / or the anti-contamination skirt 116 are assembled in a reversible manner, so as to allow the replacement of the anti-contamination skirt 116 and / or the anti-contamination jacket 117 without damaging the parts.

[0290] The anti-contamination hood 106 thus formed is hermetic, that is to say forms with the parts to be welded 30 and the welding unit 103 a hermetically sealed space.

[0291] There is shown a welding device 1 according to the invention placed opposite parts to be welded 30 having a flat surface 113, a curved surface 114, and a tubular surface 115.

[0292] The welding device 1 is shown according to an embodiment of the invention in which the welding device 1 comprises a vacuum pump 120 connected by a suction channel 160 to the hermetically sealed space formed by the anti-contamination hood 106 and the parts to be welded 30, and arranged for the evacuation of metal vapors.

[0293] The welding device is shown according to an alternative embodiment in which the anti-contamination cover 106 comprises at least one part made of a porous material.

[0294] The anti-contamination hood 106 thus comprises a plurality of orifices 121 arranged for the evacuation of welding vapors.

[0295] Advantageously, the use of an anti-contamination hood 106 comprising at least one orifice 121 makes it possible to avoid an accumulation of metal vapors inside the anti-contamination hood.

[0296] In this embodiment, the anti-contamination envelope 117 is made of a porous material, for example a metal foam or a lattice structure.

[0297] In particular, the anti-contamination envelope comprises a plurality of porous layers 122, for example by a plurality of perforated plates.

[0298] A welding device 1 is shown according to an embodiment of the invention in which the anti-contamination cover 106 comprises evacuation channels 123.

[0299] The exhaust channels 123 are internal channels, and extend inside the anti-contamination hood 106.

[0300] The discharge channels 123 comprise an end 124 placed close to the weld pool 105 generated by the welding unit, and an end 125 connected to an orifice 121 of the anti-contamination cover 106.

[0301] The exhaust channels 123 are arranged for the circulation of welding vapors from the welding bath 105 to the outside of the anti-contamination hood 106.

[0302] According to an embodiment not shown, the discharge channels 123 comprise one end placed close to the solder bath generated by the soldering unit 103 and one end connected to the vacuum pump 120, and are arranged for the circulation of solder vapors from the solder bath to the vacuum pump.

[0303] This figure also shows a protective shield 126 of the anti-contamination cover 106.

[0304] The protective shield 126 is placed inside the anti-contamination hood 106, around the main axis 15 of the welding unit 103, and is arranged to limit the presence of welding ejecta and welding vapors along the main axis of the welding device.

[0305] The protective shield 126 is in particular arranged to minimize, in a plane normal to the main axis of the welding unit, the passage surface 128 that ejecta emitted by the weld pool and moving in a straight line could cross to reach the welding unit 103.

[0306] This passage surface 128 minimized by the protective shield 126 also influences the flow of metal vapors which can propagate along the main axis 15 of the welding unit 103 and which can disrupt the welding.

[0307] In the case of laser welding or electron beam welding, the protective shield 126 thus advantageously makes it possible to limit the disturbance of the beam by vapors or ejecta which could alter the quality of the weld.

[0308] The protective shield 126 has a layered structure, and the exhaust channels 123 are formed between the layers of the protective shield.

[0309] According to an embodiment not shown, the protective shield 126 and / or the evacuation channels 123 are tubular in shape.

[0310] The protective shield 126 and the evacuation channels 123 are formed as a unit with the anti-contamination envelope 117.

[0311] According to an embodiment not shown, the protective shield 126, the evacuation channels 123 and / or the anti-contamination envelope 117 may be separate parts.

[0312] A welding device 1 is shown according to an embodiment in which the welding device is inclined, and the reference angle α0 is equal to 45°.

[0313] The welding device 1 is inclined so that the welding zone 21 is placed behind the welding unit 103 in the direction of movement of the welding device.

[0314] The anti-contamination hood 106 shown in this figure comprises a capture zone 129 for the welding vapors, arranged to allow condensation of the welding vapors on the walls of the anti-contamination hood 106.

[0315] The weld creates a pressure differential, with a high pressure close to the weld pool 105, and a negative gradient away from the weld pool. This pressure differential causes the welding vapors to move from the weld pool 105 to at least orifices 121 arranged for the evacuation of the welding vapors.

[0316] The welding vapor capture zone 129 is arranged to increase the circulation time of the welding vapors within the anti-contamination hood, so as to allow cooling and condensation of the welding vapors on the surfaces of the anti-contamination hood 106, so as to limit the quantity of metal vapors ejected from the anti-contamination hood.

[0317] In one embodiment where the anti-contamination hood 106 includes exhaust channels 123, the exhaust channels are also arranged to increase the circulation time of the solder vapors within the anti-contamination hood.

[0318] The welding vapor capture zone 129 is domed in shape, in particular a dome 130, and is formed by the anti-contamination envelope.

[0319] In an embodiment not shown, the welding vapor capture zone 129 may be formed by the anti-contamination skirt 116, by the anti-contamination envelope 117, by an evacuation channel 123 or by the protective shield 126.

[0320] The welding vapor capture zone 129 is placed vertically above the welding zone 21, i.e. opposite the surface of the parts to be welded 30.

[0321] In the embodiment illustrated in the protective shield 126 is planar in shape, and forms a pierced disc allowing the passage of the electron beam along the main axis 15 of the welding unit 103.

[0322] A front view and a top view of a welding device 1 according to an embodiment in which the parts to be welded 30 are tubular in shape, and the anti-contamination hood 106 completely surrounds a tubular section 131 of the parts to be welded are shown.

[0323] A welding device 1 is shown according to an embodiment in which the welding unit 103 comprises an orientation element 132 arranged to modify the orientation of the main axis 15 of the welding unit 103 relative to the welding device 1, in particular relative to the welding unit 103, during welding.

[0324] The steering element 132 is a focusing coil placed on the path of the electron beam, in particular on the main axis 15 of the welding unit 103 and arranged to direct the electron beam.

[0325] In an embodiment not shown, the steering element 132 may be a controllable joint of a welding electrode, or a movable lens or mirror placed in the path of a laser beam.

[0326] The welding device 1 is arranged to remain stationary relative to the parts to be welded 30 during welding. Thus, the movement of the welding zone 21 along the junction 104 between the parts to be welded 30 is achieved by changing the orientation of the main axis 15 of the welding unit 103 relative to the welding device by the orientation element 132.

[0327] A welding device 1 is shown according to an embodiment in which the anti-contamination skirt 116 comprises two walls 140 superimposed with a spacing 141 between them.

[0328] The anti-contamination skirt comprises at least one part 141 made of flexible material, for example a polymer.

[0329] Alternatively, the flexible material part is made of metal, for example the flexible material part is a comb or a metal brush, and is arranged to be able to be deformed in contact with the parts to be welded.

[0330] The walls 140 of the anti-contamination skirt 116 have substantially the shape of a conical truncated shape, the large base of which is opposite the parts to be welded 30.

[0331] The evacuation channels 123 are formed between the walls 140 of the anti-contamination skirt 116, and have a revolution shape.

[0332] The invention also relates to a method of welding in a vacuum, in particular in the vacuum of space, comprising the step of carrying out welding between them of at least two parts to be welded using a welding device as described above.

Claims

Electron beam welding device (1) comprising:a cathode (2) having an emitting surface (9) emitting electrons,an anode (3) with an anode hole (4), to which a positive voltage is applied relative to the cathode so as to create an electron beam (5) from the cathode to the anode,a beam forming electrode (6) having a flared surface (7), arranged to shape the electron beam emitted between the cathode and the anode,characterized in that a portion (8) of the flared surface of the beam forming electrode (6) extends behind the emitting surface (9) of the cathode in the direction of emission of the electron beam. Welding device (1) according to claim 1, wherein the cathode (2), the anode (3) and the beam forming electrode (6) are parts of revolution having as their axis the main emission axis of the electron beam (15). Welding device (1) according to one of the preceding claims, in which the flared surface (7) of the beam-forming electrode (6) is a cone of half-angle α, in other words forms with the main emission axis (15) an angle α, with α between 20° and 80°, in particular between 32.5° and 67.5°, in particular between 40° and 60°. Welding device (1) according to one of claims 1 to 2, wherein the flared surface (7) of the beam forming electrode is concave, or domed. Welding device (1) according to one of the preceding claims, in which the voltage difference between the anode (3) and the cathode (2) is a voltage U1 known as “low high voltage”, i.e. a voltage U1 less than 35kV, in particular less than 30kV, in particular between 10kV and 20kV. Welding device (1) according to one of the preceding claims, comprising a power supply unit (24) comprising:a power supply source (25), in particular a direct voltage source,at least one high voltage converter (26), powered by the power supply source and arranged to provide a high voltage power supply,at least one current converter (27), powered by the power supply source and arranged to provide a high current power supply, in particular to provide a current of intensity I greater than 1A, in particular equal to 3A,a power circuit (28), electrically connected to the high voltage converters and to the current converter. Welding device (1) according to one of the preceding claims, in which the cathode (2) and the anode (3) are separated by a first isolation distance D1 along the main emission axis (15) of the electron beam (5), this isolation distance D1 being between 3mm and 15mm. Welding device (1) according to one of the preceding claims, in which the minimum distance D2 along the main emission axis (15) between the start plane of the flared surface (18) and the emission plane (14, 14a) of the emitting surface (9) closest to the start plane of the flared surface is between 0.001mm and 0.5mm. Welding device (1) arranged to carry out welding between them of at least two parts to be welded (2), the welding device comprising:a welding unit (103) arranged to carry out welding along the junction (104) of two parts to be welded, generating a weld pool (105) at a welding zone (21),an anti-contamination hood (106) arranged to be placed, in particular mobile, in contact with the parts to be welded (30) so that the welding unit (103) and the anti-contamination hood (106) encompass the entire weld pool (105) and that any half-line (107) starting from the weld pool intersects either the anti-contamination hood or the welding unit,the welding device (1) being in particular arranged to move the weld pool (21) relative to the parts to be welded during welding. Welding device (1) according to claim 9, wherein the anti-contamination cover (106) comprises at least one part made of flexible material, for example a polymer. Welding device (1) according to one of claims 9 to 10, wherein the anti-contamination cover (106) comprises: an anti-contamination skirt (116), an anti-contamination casing (117), the welding unit (103), the anti-contamination casing (117) and / or the anti-contamination skirt (116) being assembled in a reversible manner, so as to allow the replacement of the anti-contamination skirt (116) and / or the anti-contamination casing (117) without damaging the parts. Welding device (1) 9 to 11, in which the anti-contamination hood (106) is hermetic, i.e. forms a hermetically sealed space with the parts to be welded (102) and the welding unit (103). Welding device (1) according to one of claims 9 to 11, in which the anti-contamination hood (106) comprises at least one orifice (121) arranged for the evacuation of welding vapors. Welding device (1) according to claim 13, wherein the anti-contamination hood (106) comprises at least one discharge channel (123) arranged for the circulation of welding vapors from the welding bath (105) towards the outside of the anti-contamination hood (6). Welding device (1) according to claim 14, in which the discharge channels (123) comprise one end (124) placed close to the weld pool (5) generated by the welding unit (3), and one end (125) connected to an orifice (121) of the anti-contamination cover (106). Welding device (1) according to one of claims 9 to 15, wherein the anti-contamination hood comprises a protective shield (126) arranged inside the anti-contamination hood (106), placed around the main axis (11) of the welding unit (103), and arranged to limit the presence of welding ejecta and welding vapors along the main axis of the welding unit. Welding device (1) according to one of claims 9 to 16, in which the anti-contamination hood (106) comprises a welding vapor capture zone (129) arranged to allow condensation of the welding vapors on the walls of the anti-contamination hood (106). Welding method carried out by a welding device (1) according to one of the preceding claims, the welding method comprising in this order the following steps: a step of placing the welding device (1) in contact with parts to be welded (30), a step of actuating the welding unit (103), starting the welding and generating a weld pool (105), a step of moving the welding zone (21) along the junction (104) between the parts to be welded (30), a step of stopping the action of the welding unit (103), ending the welding, optionally, a cooling step, a step of withdrawing the welding device (1), comprising a step of moving the welding device away from the parts to be welded (30). Welding method according to claim 18, wherein the step of moving the welding zone (21) along the junction (104) between the parts to be welded (30) comprises a step of lateral movement of the welding device (1) in contact with the parts to be welded. Method of welding in a vacuum, in particular in the vacuum of space, comprising the step of carrying out welding between them of at least two parts to be welded using a welding device (1) according to one of the preceding claims.

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