Arc welding system, and arc welding method using such a system

Abstract

The present application relates to an arc welding system (1) for welding two parts (P) together, comprising at least one base (2) movable relative to the surface of one of the parts (P) to be welded in a direction of travel (D), a torch support (6) arranged to receive an arc welding torch (T) of the type employing a wire electrode (F), a first actuator (10) and a second actuator (11) for moving the support (6) relative to the base (2) in a plane (Pt) substantially transverse to the direction of travel (D) of the base (2) relative to the parts (P) and in two different directions each non-parallel to the longitudinal axis (L) of the torch, and a control unit (20) configured to control the first and second actuators (10, 11) in a coordinated manner as a function of the trajectory to be imparted to an end (30) of the wire electrode (F).

Description

[0001] Description

[0002] ARC WELDING SYSTEM, AND ARC WELDING METHOD USING SUCH A SYSTEM

[0003] Technical field

[0004] The present invention relates to the welding of parts, in particular for the automotive, aeronautical, civil engineering, naval, metal construction and railway industries.

[0005] The invention relates in particular to mobile arc welding systems suitable for different welding configurations.

[0006] Prior art

[0007] In order to reduce the amount of material deposited during a weld between two parts, it is known to reduce the opening angle of the chamfer, in particular to angle values ​​less than or equal to 40°.

[0008] In such a configuration, to obtain good penetration and limit the risks of welding defects, it is necessary to tilt the torch electrode wire to bring it as close as possible to the normal to the surface of the bevel.

[0009] On current mobile welding carriages with pendulum axis, the oscillation amplitude is limited due to the distance between the contact point and the rotation point, which does not allow for an inclination greater than 5°. This does not allow for good orientation of the wire electrode on the sheet metal. Therefore, these welds are generally carried out manually by an experienced operator.

[0010] Similarly, to weld sheets at right angles, the actuators that move the welding torch currently have to be mechanically oriented manually before the weld is made. In addition, during welding, the scanning that is carried out is done with a torch whose orientation remains identical. Thus, the orientation of the wire electrode at the ends of the weld bead is relatively far from the local normal, which does not allow good penetration of the weld.

[0011] For the cases described above, it is known to use welding torches with a particular geometry. However, such torches are only suitable for one type of welding. It is therefore necessary to change the torch depending on the geometry of the weld to be made, which complicates the welding process and increases the purchase and operating costs. There is a need for a mobile welding system that allows, during welding, to maintain a good orientation of the wire electrode, while simplifying the use of the system.

[0012] Statement of the invention

[0013] The present invention meets this need thanks to an arc welding system for welding two parts together, comprising at least:

[0014] - a base movable relative to the surface of one of the parts to be welded in a direction of advance,

[0015] - a torch holder arranged to receive a wire-electrode arc welding torch,

[0016] - a first actuator and a second actuator for moving the support relative to the base in a plane substantially transverse to the direction of advancement of the base relative to the parts and in two different directions and each not parallel to the longitudinal axis of the torch,

[0017] - a control unit configured to control the first and second actuators in a coordinated manner depending on the trajectory to be given to one end of the electrode wire.

[0018] Thanks to the invention, it is possible to perform welds on different geometries without having to manually and beforehand modify the position on the basis of the first and / or second actuators. This facilitates the installation of the system and limits the risks of incorrect positioning of the torch during welding.

[0019] In addition, the coordinated control of the first and second actuators allows precise positioning of the welding torch, thus optimizing the trajectory of the wire electrode and the weld.

[0020] The system also allows the use of a standard welding torch, which limits the cost of purchasing equipment. In addition, this limits the need for training on different types of equipment, as manual welding and welding on the system are carried out with the same torch, or even with the same welding station.

[0021] By "moving the support relative to the base in a plane substantially transverse to the direction of advance of the base relative to the parts", it is meant that the movement of the torch caused by the actuator(s) is done entirely in said plane substantially transverse to the direction of advance, that is to say that the movement of the torch by the actuator(s) does not cause movement of the torch outside of said plane. By "a plane substantially transverse to the direction of advance of the base relative to the parts", it is meant a plane whose normal forms an angle with the direction of advance of the base relative to the parts of less than 20°, better still less than 10°, even better still less than 5°, an angle of 0° forming a perfectly transverse plane.

[0022] Actuators

[0023] The torch holder may be connected to the first and / or second actuators by a remote arm.

[0024] The first actuator can be linear or rotary.

[0025] The second actuator can be linear or rotary.

[0026] The linear actuator(s) allow the torch support to be moved in translation.

[0027] In one embodiment, the first actuator is linear and the second actuator is rotary and allows the torch to be moved in rotation, preferably along an axis substantially parallel to the direction of advancement.

[0028] In another embodiment, the first and second actuators are linear, the directions of movement of the linear actuators preferably being orthogonal to each other. In this case, the torch holder may be connected to the first and second actuators by a remote arm.

[0029] In another embodiment, the first actuator is linear, the second actuator is rotary and allows the torch to be moved in rotation, preferably along an axis substantially parallel to the direction of advancement, and in which the system comprises a third linear actuator which allows the torch to be moved in translation, the directions of movement of the linear actuators preferably being orthogonal to each other.

[0030] The use of a rotary actuator allows the orientation of the torch to be adapted during the welding operation, in particular to maintain an orientation of the welding torch as close as possible to the normal of the surface on which the weld is made.

[0031] By "axis substantially parallel to the direction of advancement" is meant an axis forming an angle with the direction of advancement at a given instant of less than 20°, better still 10°, even better 5°. Where appropriate, the rotary actuator is positioned at the torch support, in particular at one end of the offset arm.

[0032] The control unit is preferably configured to coordinately control the first, second and third actuators depending on the path to be given to the end of the wire electrode. Such coordinated control allows great freedom in the movement of the torch, which promotes optimal orientation of the welding torch.

[0033] The first, second and, where appropriate, third actuator may each comprise a motor and a position sensor.

[0034] One of the actuators can move a first intermediate support in a Y direction generally parallel to the plane of the base. The other actuator can be carried by the first intermediate support and move a second intermediate support in a Z direction perpendicular to the Y direction. The third actuator can be carried by the second intermediate support and rotate the aforementioned torch support about an X axis perpendicular to the Z and Y axes.

[0035] Base

[0036] The base can be a mobile trolley, a gantry or a rotating column.

[0037] The base, in particular the carriage, may comprise wheels, in particular each with an axis of rotation perpendicular to the direction of travel, and / or tracks, in particular motorized, allowing it to move along the parts to be welded. The carriage may be moved by rolling over the parts to be welded, or on at least one guide rail, or even on a rack. The carriage may be guided, if necessary, by resting on one of the parts to be welded, in particular when this is a stiffener.

[0038] The base, including the trolley, may have four motorized wheels, each wheel being able to be controlled independently of the others in order to steer the base in the desired direction.

[0039] The base, in particular the trolley, may include at least one, or even two, sets of wheels, in particular a right set and a left set, independently motorized.

[0040] The use of wheels allows for rail-free guidance and therefore limited installation logistics. The base can have a gripping element allowing the operator to grasp and carry the base, for example with one hand.

[0041] The base may include a power supply system, such as a battery. Using a battery eliminates the need for a bulky external power cable.

[0042] The base may include one or more magnets ensuring its retention by magnetic attraction on one of the parts to be assembled.

[0043] Control and guidance

[0044] The control unit can be programmed to perform welding autonomously and / or semi-autonomously.

[0045] By "autonomously" we mean that the system is capable of performing the welding without the intervention of an operator.

[0046] By "semi-autonomously" we mean that the system is capable of performing the weld under the supervision of an operator, the operator being able to transmit orders to the system in order to correct certain parameters of movement of the base or the weld.

[0047] The control unit can include any processor, for example microcontroller and the interfaces to interact with the environment of the latter, for example sensor(s), power stage for controlling the motors, HMI, transmitter / receiver to exchange with a wireless remote control.

[0048] The control unit may optionally be removably mounted on the system, particularly on the base. In this case, the system may include a receiving area with a series of connectors for mounting the control unit on the base.

[0049] The system may include a remote control, in particular a wireless one, preferably a remote control, allowing an operator to remotely control the movement of the base relative to the parts to be welded, in particular the speed of advance of the base, the direction of movement of the base, and / or welding parameters.

[0050] The remote control can also be configured to provide information on the geometry of the weld to be made.

[0051] The control unit may be configured to receive, via a user interface or remote control, data on the geometry of the weld to be made, the data possibly including the angle between the two parts, the opening angle of a chamfer between the parts, the material of the parts and / or the thickness of the parts. The control unit may be arranged to automatically determine, based on this received data, one or more operating parameters of the base and the actuators.

[0052] The system may include a transceiver communicating with the remote control, included in the control unit or independent.

[0053] The system may comprise a guide means, in particular comprising at least one guide rail. This guide rail may be fixed magnetically or otherwise to one of the parts.

[0054] The system may include a guide laser forming a visual reference on the parts to be welded, in particular positioned on the edge of the bevel of the welding joint, to guide the base.

[0055] The system may include a part geometry sensor, in particular a profilometer, preferably a laser, measuring the profile of the parts to be welded upstream of the welding torch in the direction of movement of the latter. The actuators can be controlled automatically based on the profile thus measured.

[0056] The system may include a guiding camera. Guidance may or may not be achieved using a reference wire placed on the parts.

[0057] Where appropriate, the control unit is configured to coordinately control the first, second and third actuators depending on the trajectory to be given to one end of the electrode wire.

[0058] Welding torch

[0059] The system may include a welding torch received by the torch holder.

[0060] The welding torch can be removably mounted on the torch holder.

[0061] The torch can be configured to feed the electrode wire while welding.

[0062] The welding torch can be a standard torch suitable for MAG or MIG welding.

[0063] The system may comprise one or two, or even more, welding torches. In this case, the system may comprise, for each torch, a torch holder, a first actuator, a second actuator and, possibly, a third actuator. Each of the torches may be offset relative to the other in the direction of travel. Welding station

[0064] The system may include a welding station, including a standard welding station suitable for open arc welding. A "standard welding station" means a welding station commonly used for open arc welding operations, such as MAG or MIG welding. Using a standard welding station can significantly reduce the cost of the system, as this type of station is commonly available commercially.

[0065] The welding station, also called a generator, can be fixed relative to the parts to be welded during the movement of the base.

[0066] Alternatively, the station may be moved during welding relative to the parts, in particular occasionally as the welding progresses. For example, the welding station is placed in a first location, and the base is moved a certain distance without moving the welding station, the hose connecting the welding torch to the welding station being deployed during this operation. Then, the welding station may be brought to a second location, which brings it closer to the base, and the welding operation continued.

[0067] Alternatively, the station can itself be equipped with wheels and be moved continuously during welding, for example towed by the base, or carried by autonomous means of transport or controlled by the movement of the base.

[0068] The welding station may include a coil of filler metal for the electrode wire. The welding material may be fed from the welding station to the welding torch through a guide, present within the aforementioned hose, for example.

[0069] The arc welding station can be a MIG (Metal Inert Gas) and / or MAG (Metal Active Gas) station, whose protective gas flow is activated, a TIG (Tungsten Inert Gas) station, a submerged arc station, a subslag welding station, a plasma station, or any other arc welding station.

[0070] The welding station may include a ground clamp configured to be positioned on at least one of the parts to be welded.

[0071] The welding station may include a control panel for controlling welding parameters, including electrical voltage, electrical current, arc speed and / or wire feed speed of the filler metal.

[0072] Welding method The invention also relates, according to another of its aspects, to a method of welding two parts together using a system as defined above, in which the base is continuously or intermittently moved relative to the parts to be welded, and, when the base is in motion and / or between two movements of the latter:

[0073] - the welding torch produces an arc,

[0074] - the welding torch is moved by coordinated movements of said first and second actuators so as to form a weld bead.

[0075] Thanks to the method according to the invention, it is possible to carry out welds on different geometries with the same system by the coordinated movements of the first and second actuators.

[0076] Indeed, the coordinated movements of the first and second actuators allow precise positioning of the welding torch at any point of a plane substantially transverse to the direction of advance in the vicinity of the welding zone, thus making it possible to optimize the trajectory of the weld.

[0077] The movements of the first and second actuators may be coordinated with the movement of the base. In particular, they may vary depending on the feed rate. For example, when the base slows down, the movement rate of the first and second actuators may also be slowed down.

[0078] When the first actuator is linear and the second actuator is rotary, the welding torch can be moved by linear movements of the first actuator coordinated with rotary movements of the second actuator making it possible to move the torch in rotation relative to the parts, in particular along an axis substantially parallel to the direction of advancement.

[0079] The welding torch can be moved by coordinated movements of the first and second actuators and a third actuator, preferably one of the three actuators being rotary, the other two actuators being linear.

[0080] The movements of the third actuator can also be coordinated with the movement of the base.

[0081] The welding torch can be scanned in a direction orthogonal to the direction of advance. The scanning can be performed at a constant spatial frequency, in particular when the weld bead to be produced has a substantially constant geometry. Alternatively, it can be variable, in particular when the weld bead to be produced has a highly variable geometry.

[0082] The weld bead produced may include a straight portion.

[0083] The weld bead produced may include a curved portion. The radius of curvature of the curved portion may or may not be constant.

[0084] Preferably, when the system comprises a rotary actuator, the position of this actuator varies during the formation of a curved portion.

[0085] For example, the weld bead may have two curved portions between which a straight portion extends.

[0086] A curved portion of the weld bead may be formed after a straight portion of the weld bead. The directions of movement of the linear actuator(s) relative to the workpieces during the formation of the curved portion are preferably reversed from those during the formation of the immediately preceding straight portion.

[0087] Preferably, when the system comprises a linear actuator and a rotary actuator, the position of the rotary actuator, in particular of the center of rotation thereof relative to the aforementioned second intermediate support, varies during the formation of a curved portion, due to the actuation of the linear actuator(s).

[0088] Coordinated movements of the first actuator, the second actuator and, where appropriate, the third actuator can rotate the welding torch relative to the parts around an axis substantially parallel to the direction of advancement and passing through one end of the wire electrode, in particular without translation of this end relative to the parts.

[0089] During the formation of the weld bead, the wire electrode may form an angle of less than 70°, preferably less than 45°, relative to the normal of the surface, in particular the bevel, to be welded opposite one end of the wire electrode.

[0090] A weld bead with a section comprising a straight portion and / or a curved portion, in particular two curved portions at each end of the straight portion, can be produced between the parts.

[0091] It is possible to produce a straight, triangular, V-shaped, fir-shaped, curved, or any desired shape of weld bead. The control unit preferably coordinates the movements of the first actuator, the second actuator and, if applicable, the third actuator so as to control the movement of the end of the wire electrode to a predetermined path of the wire electrode.

[0092] To control the movement of the end of the electrode wire, the control unit can change the reference formed by the axes of the actuators towards one end of the electrode wire.

[0093] The change of reference frame may constitute a change from the orthonormal reference frame formed by the displacement axes of the first and second actuators, when these are linear, to an orthonormal reference frame centered on the end of the electrode wire, one of the axes of this reference frame being coincident with the longitudinal axis of the electrode wire.

[0094] The change is preferably carried out in such a way that the axes of the reference points before and after transfer are included in the same plane, preferably substantially transverse to the direction of advancement.

[0095] For example, when the first and second actuators are linear, to move the wire electrode by a distance A in a direction of movement orthogonal to the longitudinal axis of the wire electrode and to the direction of advancement, and if a is the smallest angle between the direction of movement of the wire electrode and the axis of movement of the second actuator, the first actuator will be moved by a distance equal to the product of A and the sine of a and the second actuator will be moved by a distance equal to the product of A and the cosine of a.

[0096] For example, when the first actuator is linear and the second actuator is rotary, if L is the distance between the end of the wire electrode and the second actuator, the distance A of displacement of the end of the fd-electrode along the axis of the first linear actuator is equal to the sum of the displacement of the first actuator and the product of 2L and the cosine of the half-angle of rotation of the second actuator. Thus, for a zero displacement along the axis of the first actuator of the end of the wire electrode and for a given angular amplitude for the wire electrode, which is therefore equal to the amplitude of rotation of the second actuator, it is possible to deduce the amplitude of displacement of the first actuator.Similarly, for a weld with a given orientation of the wire electrode, therefore a fixed angular position for the second actuator, and for an amplitude A of displacement of the end of the wire electrode, it is possible to deduce the amplitude of movement of the first actuator.

[0097] For example, for a first linear actuator and a second linear actuator and a third rotary actuator, to rotate the welding torch around the end of the wire electrode by an angle P, if a is the smallest angle between the axis of movement of the second actuator and an axis orthogonal to the longitudinal axis of the wire electrode in a plane transverse to the direction of advancement before rotation and if L is the distance between the end of the wire electrode and the third actuator, the first actuator will be moved by L(sin(a+ P) - sin(a)), the second actuator will be moved by L(cos(a) - cos(a+ P)) and the third actuator will rotate by an angle p.

[0098] Preferably, the axis of movement of one of the actuators, in particular the first actuator, is parallel to one of the parts during welding.

[0099] Part to be welded

[0100] The two pieces can form different angles with each other, including an angle of about 90° or about 180°.

[0101] The parts may have between them a chamfer forming an opening between them with an angle less than or equal to 100°, in particular with an angle less than or equal to 60°, for example less than or equal to 40°.

[0102] The pieces may have a chamfer between them with a heel in the lower part.

[0103] The parts may be metallic, including steel, stainless or not, aluminum or one of its alloys.

[0104] The parts can be sheet metal.

[0105] Brief description of the drawings

[0106] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which

[0107] [Fig 1] Figure 1 illustrates, in front view, schematically, an example of a system according to the invention positioned on flat parts to be welded,

[0108] [Fig 2] Figure 2 is a view similar to Figure 1 illustrating the system during a welding process according to the invention, [Fig 3] Figure 3 illustrates the progress of the welding process of Figure 2,

[0109] [Fig 4] Figure 4 illustrates, in front view, schematically, another example of a system according to the invention positioned on parts forming a right angle between them,

[0110] [Fig 5] Figure 5 and an enlargement of Figure 4 according to V,

[0111] [Fig 6] Figure 6 is a view similar to Figure 5 illustrating the formation of a straight portion of a weld bead,

[0112] [Fig 7] Figure 7 is a view similar to Figure 5 illustrating the formation of a curved portion of a weld bead, and

[0113] [Fig 8] Figure 8 illustrates, in top view, schematically, the system of Figure 7.

[0114] Detailed description

[0115] In the remainder of the description, elements that are identical or have identical functions bear the same reference sign. For the sake of brevity in this description, they are not described with reference to each of the figures, only the differences between the embodiments being described.

[0116] In the figures, the actual proportions have still not been respected, for the sake of clarity.

[0117] Figure 1 illustrates an example of system 1 for welding two parts P together.

[0118] The system comprises a base, in this example a carriage 2, arranged to move on the surface of one of the parts P in a direction of advancement D.

[0119] In this example the trolley 2 has a platform 3 mounted on wheels 4, in this example four, only two being visible in figure 1.

[0120] Each wheel 4 is driven.

[0121] System 1 includes a holder 6 for a wire-electrode arc welding torch T.

[0122] The welding torch T is, for example, a standard torch used for MIG or MAG welding, a TIG station, a submerged arc station, a slag welding station, a plasma station, or any other arc welding station. The torch T is, in this example, connected to a standard welding station, not shown for the sake of clarity in the drawings.

[0123] The system 1 also comprises, mounted on the platform 3, a first linear actuator 10, connected by means of a deportation arm 15 to a second rotary actuator 11, itself connected to the torch support 6 T.

[0124] The first actuator 10 makes it possible to move the arm 15, and therefore the second actuator 11, the support 6 and the torch T, in translation relative to the carriage 2 in direction Y orthogonal to the normal of the surface of the base 3.

[0125] The Y axis is not parallel to the longitudinal axis L of the torch T.

[0126] The second actuator 11 has an axis X of rotation parallel to the direction of advancement D.

[0127] Both actuators 10 and 11 operate with motors and position sensors.

[0128] The system 1 also comprises a control unit 20 configured to control in a coordinated manner the first actuator 10 and the second actuator 11 as a function of the trajectory to be given to the end 30 of the electrode wire F.

[0129] The control unit 20 allows welding to be carried out autonomously or semi-autonomously.

[0130] The control unit 20 is, in this example, removably mounted on the platform 3 on a reception area.

[0131] The control unit 20 also includes a rechargeable battery providing its electrical power supply and that of the actuators 10 and 11.

[0132] The system 1 comprises a wireless remote control 21 communicating with the control unit 20 via a transmitter-receiver system or by wired connection when the latter is placed on it.

[0133] The remote control 21 forms a user interface allowing an operator to remotely control and, if necessary, correct the movement of the trolley 2.

[0134] The remote control 21 also makes it possible to enter data on the geometry of the weld to be made, such as for example the angle between the parts P, the thickness of the parts P or the angle of a chamfer between the parts P. The system 1 comprises, in this example, a laser profilometer 22 measuring the profile of the parts P upstream of the welding torch T in the direction of advance D thereof.

[0135] Figures 2 and 3 illustrate a first example of a welding process using a system 1 as described previously.

[0136] In this first example, the P pieces are both flat. They each have a chamfer forming between them an opening at an angle Oc of 40°.

[0137] First, the system 1 is positioned on the outer surface of one of the parts P. Then, for example with the remote control 21, a user transmits to the control unit 20 information on the geometry of the parts P.

[0138] The torch T is then moved into position for welding.

[0139] The carriage 2 is then set in motion in direction D and, at the same time, the wire electrode E produces an arc with one of the parts and is unwound by the torch T, to form the weld bead J. In this example, the base 2 moves continuously or intermittently.

[0140] The first actuator 10 and the second actuator 11 move, by coordinated movements controlled by the control unit 20, the torch T to form the welding bead J.

[0141] As illustrated in Figure 2, the two actuators 10 and 11 are moved so as to maintain the longitudinal axis L of the wire electrode E close to the normal N of the surface opposite the end 30 of the wire electrode E. In this example, the longitudinal axis L of the torch T forms with the normal N an angle Os less than 15°.

[0142] To produce the weld bead J, the torch T is moved so as to produce a sweep orthogonal to the direction D. During this sweep, by coordinated movements of the two actuators 10 and 11, the orientation of the torch T is modified so as to maintain the longitudinal axis L of the wire electrode F as close as possible to the normal N of the surface on which the weld bead J is formed.

[0143] In this respect, Figure 3 illustrates the position of the welding torch T after an initial sweep from left to right. In this position, and during the sweep, the angle Os remains less than 15°.

[0144] Maintaining this orientation is obtained by coordinated movements of the two actuators 10 and 11. For example, when the torch T moves from the left position of Figure 2 to the right position of Figure 3, the first actuator 10 moves from left to right along the Y axis and the second actuator 11 rotates in an anti-clockwise direction relative to the direction D around the X axis. Alternatively, it is possible for the first actuator 10 to be fixed.

[0145] Such an orientation of the wire electrode F during scanning allows for good impact of the wire electrode F, good penetration of the weld and therefore good adhesion of the weld. This allows for a weld bead J to be obtained with good geometry and no or few defects.

[0146] Apart from the movement of the carriage 2, the scanning is carried out for example from right to left then from left to right, until the end of the weld. In this example, the scanning movements, and therefore those of the two actuators 10 and 11, are coordinated with the movement of the carriage 2 so as to obtain a scanning with a relatively constant frequency. The wire electrode feed speed F can be coordinated with the scanning speed and / or the movement speed of the carriage 2.

[0147] Figures 4 to 7 illustrate a variant of the system and method in which the two parts P form a right angle with each other and where the system comprises three actuators 10, 11 and 12.

[0148] In this example, the first actuator 10 and the second actuator 11 are identical to the previous example. The first actuator 10 also makes it possible to move the third actuator 12 in translation.

[0149] The third actuator 12 makes it possible, in this example, to move the arm 15, and therefore the second actuator 11, the support 6 and the torch T, in translation relative to the carriage 2 in direction Z normal to the surface of the platform 3 and transverse to the direction of advancement D.

[0150] In this example, the weld bead J to be produced has, in a plane transverse to the direction of advancement D, a substantially triangular section.

[0151] As illustrated, the Y axis of movement of the first actuator 10 and the Z axis of movement of the third actuator 12 are orthogonal to each other, are included in a plane transverse to the direction of advancement D and not parallel to the longitudinal axis F of the wire F of the torch T. The X axis of rotation of the second actuator 11 is, as previously, parallel to the direction of advancement D.

[0152] In this example, base 2 is set in motion intermittently.

[0153] The scanning trajectory Tb that the end 30 of the wire electrode F carries out during the welding operation is illustrated in the partial enlargement of figure 4 given in figure 5.

[0154] This trajectory Tb includes a straight portion Tbl and two curved portions Tb2 and Tb3.

[0155] The scanning is carried out periodically, for example by first carrying out the curved portion Tb2, then the straight portion Tb1, then the curved portion Tb3, then again the straight portion Tbl and so on. This scanning is preferably carried out when the carriage 2 is moving.

[0156] It is also possible to carry out a plunge of the electrode wire F in the middle of the straight portion Tbl, forming a so-called fir-tree weld.

[0157] To realize the straight portion Tbl, as illustrated in Figure 6, the linear actuators 10 and 12 are actuated while the rotary actuator 11 keeps the same orientation.

[0158] The displacement of the third actuator 12 along the Z axis produces a displacement ZI of the end 30 of the torch T. In this example, the displacement of the third actuator 12 along Z is equal to the product of the norm of Dt and the sine of the smallest angle a between Dt and the Z axis.

[0159] The angle a also corresponds to the smallest angle between the Z axis and an axis orthogonal to the longitudinal axis L of the electrode wire F in a plane transverse to the direction of advancement D.

[0160] The displacement of actuator 10 along the Y axis produces a displacement Y1 of the end 30 of the torch T. In this example, the displacement of the first actuator 10 along Y is equal to the product of the norm of Dt and the cosine of the angle a.

[0161] The sum of the displacements along the ZI and Y1 axes produces a displacement Dt of the end 30 of the torch T, in a plane transverse to the direction of advancement D.

[0162] The second actuator 11, during the formation of the straight portion, also moves in the direction Dt. As illustrated, during the formation of the straight portion Tbl, the longitudinal axis L of the wire electrode F coincides with the normal of the surface N on which the weld is made, in this case on a part of the weld bead J already made.

[0163] The formation of the curved portion Tb2 which follows the formation of the straight portion Tbl of Figure 6 is illustrated in Figure 7.

[0164] To produce the curved portion Tb2, the welding is carried out by rotating the wire electrode F along an axis XI parallel to the direction of advancement D and passing through the end 30 of the wire electrode F, this axis XI being positioned at the center of curvature of the curved portion Tb2.

[0165] Thus, to form the curved portion Tb2, the end 30 can only be moved in rotation. There is, for example, no translation of the end 30. Alternatively, there may be a slight translation.

[0166] This rotation around the end 30 requires linear movements of the first actuator 10 and the third actuator 12 along the Z and Y axes in directions opposite to those during the formation of the straight portion Tbl.

[0167] The second actuator 11 is, during the formation of the curved portion Tb2, rotated around the axis X in the same direction of rotation as that of the end 30 around the axis XL

[0168] In Figure 7, the axis Fi is an axis orthogonal to the longitudinal axis L of the wire electrode F in a plane transverse to the direction of advancement D before rotation and the axis F2 illustrates the longitudinal axis L of the wire electrode F before rotation.

[0169] As illustrated, to form the curved portion, the wire electrode F is rotated by an angle P relative to the axis F2.

[0170] To make this rotation, the third actuator 12 was moved along the Z axis by Lo(sin(a+ P) - sin(a)), the first actuator 10 along the Y axis by Lo(cos(a) - cos(a+ P)) and the second actuator rotated around X by an angle P, Lo being the length between the end 30 and the second actuator 11.

[0171] The different movements of the linear actuators 10 and 12 also produce a linear displacement of the second actuator 11 relative to the parts P in a direction Dtl. This particular movement of the torch T around the end 30 makes it possible to maintain the longitudinal axis L of the wire electrode F as close as possible to the normal N of the surface opposite the end 30.

[0172] For example, the angle Os here is less than 10°.

[0173] To create the curved portion Tb3, we proceed in a similar manner, the different directions of movement or rotation being reversed compared to those during the formation of the curved portion Tb2.

[0174] These movements of the three actuators 10, 11 and 12, during the formation of the different portions, are coordinated by the control unit 20.

[0175] In particular, the control unit 20 coordinates the movements so as to control the movement of the end 30 of the electrode wire F relative to a predetermined trajectory thereof.

[0176] In a variant illustrated in Figure 8, the actuators 10, 11 and 12 can allow the movement of the torch T in a plane Pt whose normal Nt forms an angle Ot, called the thrust angle, of 5° relative to the direction of advance D.

[0177] In a variant not shown, the angle Ot could be reversed, i.e. the torch T points slightly in the direction of advance D.

[0178] The invention just described is not limited to the examples just described.

[0179] In particular, the angle between the parts P can be different open or closed, for example between 0° and 360°.

[0180] The J weld bead section can have a different number of curved portions, for example between 1 and 4.

[0181] The J weld bead can have a different number of straight portions, for example between 1 and 4.

[0182] The movements of the three actuators 10, 11 and 12 can be coordinated so as to form a curved portion by a rotation of the torch T around the end 30 and a translation of this end.

[0183] The movements of the actuators 10, 11 and 12 can be carried out in a plane whose normal forms an angle of less than 20° with the direction of advancement of the base.

Claims

Claims 1. Arc welding system (1) for welding two parts (P) together, comprising at least: - a base (2) movable relative to the surface of one of the parts (P) to be welded in a direction of advancement (D), - a torch (T) support (6) arranged to receive a wire-electrode arc welding torch (T) (F), - a first actuator (10) and a second actuator (11) for moving the support (6) relative to the base (2) in a plane (Pt) substantially transverse to the direction of advancement (D) of the base (2) relative to the parts (P) and in two different directions and each not parallel to the longitudinal axis (L) of the torch, - a control unit (20) configured to control in a coordinated manner the first and second actuators (10, 11) according to the trajectory to be given to one end (30) of the electrode wire (F).

2. System (1) according to claim 1, in which the first actuator (10) is linear and the second actuator (11) is rotary and allows the torch (T) to be moved in rotation, preferably along an axis (X) substantially parallel to the direction of advancement (D).

3. System (1) according to claim 1, wherein the first and second actuators (10, 11) are linear, the directions (Y, Z) of movement of the linear actuators (10, 11) being preferably orthogonal to each other.

4. System (1) according to claim 1, in which the first actuator (10) is linear, the second actuator (11) is rotary and allows the torch to be moved in rotation, preferably along an axis (X) substantially parallel to the direction of advancement (D), and in which the system comprises a third linear actuator (12) which allows the torch (T) to be moved in translation, the directions (Y, Z) of movement of the linear actuators (10, 12) being preferably orthogonal to each other.

5. A system according to any preceding claim, wherein the base (2) is a mobile trolley, gantry or rotating column.

6. System (1) according to any one of the preceding claims, in which the base (2) comprises wheels (4), in particular each with an axis of rotation perpendicular to the direction of advance (D), and / or tracks, in particular motorized, allowing its movement along the parts (P) to be welded.

7. System (1) according to any one of the preceding claims, comprising at least one geometry sensor (22) of the parts (P) measuring the profile of the parts (P) to be welded upstream of the welding torch (T) in the direction of movement thereof, the control of the actuators (10, 11, 12) being able to be done automatically as a function of the profile thus measured.

8. System (1) according to any one of the preceding claims, comprising a welding torch (T) received by the torch (T) support (6).

9. Method for welding two parts (P) together using a system (1) according to any one of the preceding claims, in which the base (2) is continuously or intermittently moved relative to the parts (P) to be welded, and, when the base (2) is in motion and / or between two movements thereof: - the welding torch (T) produces an arc, - the welding torch (T) is moved by coordinated movements of said first and second actuators (10, 11) so as to form a weld bead (J).

10. Method according to the preceding claim, in which the movements of the first and second actuators (10, 11) are coordinated with the movement of the base (2).

11. Method according to one of claims 9 and 10, in which the first actuator (10) is linear, the second actuator (11) being rotary, the welding torch (T) being moved by linear movements of the first actuator (10) coordinated with rotary movements of the second actuator (11) making it possible to move the torch (T) in rotation relative to the parts (P), in particular along an axis (X) substantially parallel to the direction of advance (D).

12. Method according to any one of claims 9 to 11, wherein the welding torch (T) is moved by coordinated movements of the first and second actuators (10, 11) and a third actuator (12), preferably one of the three actuators (10, 11, 12) being rotary, the other two actuators (10, 11, 12) being linear.

13. Method according to any one of claims 9 to 12, in which a sweep of the welding torch (T) is carried out in a direction orthogonal to the direction of advancement (D).

14. Method according to any one of claims 9 to 13, in which the weld bead (J) produced comprises a straight portion and / or a curved portion.

15. Method according to any one of claims 9 to 14, in which a curved portion (Tb2, Tb3) of the weld bead (J) is produced after a straight portion (Tbl) of the weld bead (J), the directions of movement of the linear actuator(s) (10, 11) relative to the parts during the formation of the curved portion (Tb2, Tb3) being reversed with respect to those during the formation of the immediately preceding straight portion (Tbl).

16. Method according to any one of claims 9 to 15, in which coordinated movements of the first actuator (10), the second actuator (11) and, where appropriate, the third actuator (12) cause the welding torch (T) to rotate relative to the parts (P) around an axis (XI) substantially parallel to the direction of advance (D) and passing through one end (30) of the wire electrode (F).

17. Method according to any one of claims 9 to 16, in which, during the formation of the weld bead (J), the wire electrode (F) forms an angle (Os) of less than 70°, preferably less than 45° relative to the normal (N) of the surface to be welded opposite one end (30) of the wire electrode (F).

18. Method according to any one of claims 9 to 17, in which a weld bead (J) is produced between the parts (P) with a section comprising a straight portion (Tbl) and a curved portion (Tb2, Tb3), in particular two curved portions (Tb2, Tb3) at each of the ends of the straight portion (Tbl).

19. Method according to any one of claims 9 to 18, in which the control unit (20) coordinates the movements of the first actuator (10), of the second actuator (11) and, where appropriate, of the third actuator (12) so as to control the movement of the end (30) of the wire electrode (F) to a predetermined trajectory of the wire electrode (F).

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