JP5499593B2 - Laser welding method and laser welding apparatus - Google Patents

Description

  The present invention relates to a laser welding method and a laser welding apparatus for two flat metal plates stacked one above the other, and belongs to the field of metal welding technology.

  In recent years, laser welding is being used to weld two metal plates stacked one above the other. This laser welding is performed by moving the laser light with respect to the two metal plates along a predetermined welding path while irradiating laser light toward the upper metal plate surface of the two metal plates. Two metal plates are melted to form a linear weld bead.

  Also, not only the metal plate but also the filler wire is melted, that is, melted by laser welding the two metal plates stacked one above the other while supplying the filler wire to the irradiated part that is irradiated with laser light. It is also known to connect two metal plates by increasing the metal.

  In this way, when laser welding is performed while supplying a filler wire to the irradiated portion of the laser beam, the filler wire and the welded portion are connected at the end of welding, and when the wire is forcibly separated, the tip of the wire In some cases, a weld failure occurs in which the metal solidified product of the welded portion adheres in a ball shape or a hole is formed in the welded portion.

  In order to cope with this, for example, in Patent Document 1, laser welding is performed while supplying a filler wire to a butt portion. However, when welding is finished and laser irradiation is stopped, a predetermined amount is applied to the filler wire. It is disclosed that an electric current is passed to cut the filler wire. For example, Patent Document 2 discloses that the supply of the filler wire is stopped at a timing before the laser irradiation stop timing.

JP-A-61-235088 JP 2001-198689 A

  By the way, in the case of laser welding two flat metal plates that are stacked one on top of the other while supplying filler wire to the irradiated part that is irradiated with laser light, the metal plate and filler wire are melted by laser light. For this reason, energy is consumed for melting the filler wire, and the metal plate may not be sufficiently melted.

  In contrast, by irradiating a laser beam toward the upper metal plate surface of the two metal plates, the metal plate is melted to form a molten pool in which the molten metal is stored. By supplying the filler wire behind the laser beam irradiated part in the welding progress direction, the energy of the laser beam can be used for melting the metal plate without being consumed for melting the filler wire. Conceivable.

  In addition, when laser welding two flat metal plates stacked one above the other, the opposing surfaces of the two metal plates are generally not perfectly flat, so there are not a few gaps between the two metal plates. According to the above method for supplying filler wire to the molten pool, even when a gap is formed on the opposing surface between the two metal plates, the filler metal is used to form the two metals. It is believed that the plates can be connected.

  However, in the case of laser welding two flat metal plates stacked on top and bottom while supplying filler wire to the molten pool, since filler wire is supplied to the molten pool, at the end of welding, When the wire is fixed to the welded part formed by solidification of the molten metal in the molten pool and is forcibly separated, the metal solidified product of the welded part is in a ball shape at the tip of the wire as described above. This results in poor welding such as adhesion or formation of a hole in the weld.

  Therefore, the present invention has been made in view of the above technical problem, and in laser welding in which two metal plates are laser-welded while supplying a filler wire to a molten pool, at the end of welding, the filler wire and the metal plate An object of the present invention is to provide a laser welding method and a laser welding apparatus that can satisfactorily detach the metal.

For this reason, in the invention according to claim 1 of the present application, predetermined energy is applied to the surface of the upper metal plate among the two flat plate-like metal plates in which a gap is generated between the surfaces facing each other in a state where they are stacked one above the other. A laser beam having a density is irradiated to form a molten pool in which the molten metal is stored by melting the metal plate, and a filler wire is located behind the irradiated portion of the laser beam in the molten pool in the welding progress direction. A laser welding method for laser welding two metal plates, wherein a laser head that irradiates laser light at the end of welding is moved so that the filler wire can be irradiated with laser light. And a second step of irradiating the filler wire with laser light having an energy density lower than the predetermined energy density from the laser head. And flop, said the filler wire in a state of radiating the laser light pull back the filler wire in the opposite direction the supply direction to the molten pool, and a third step of disconnecting said metal plate and the filler wire, In the first step, the laser head is moved so that the irradiated portion of the laser light includes a portion where the filler wire enters the molten pool .

The invention according to claim 2 of the present application is characterized in that, in the laser welding method according to claim 1 , in the first step, the laser head is translated or rotated to the filler wire side. It is a thing.

Furthermore, in the invention according to claim 3 of the present application, predetermined energy is applied to the surface of the upper metal plate of the two flat metal plates in which a gap is formed between the surfaces facing each other in a state where they are stacked one above the other. A laser head that irradiates a laser beam having a density, melts the metal plate to form a molten pool in which molten metal is stored, and is located behind the irradiated portion of the laser light in the molten pool in the welding progress direction. Wire supply means configured to be able to supply a filler wire and pull back the filler wire in a direction opposite to the supply direction to the molten pool, and supplying two sheets while supplying the filler wire to the molten pool A laser welding apparatus for laser welding a metal plate of the metal plate, and at the end of welding, the movement of the laser head is controlled so that the filler wire can be irradiated with laser light. And controlling the operation of the laser head to irradiate the filler wire with laser light having a lower energy density than the predetermined energy density from the laser head, and irradiating the filler wire with the laser light. in pulling back the filler wire in the opposite direction the supply direction to the molten pool further example Bei control means for controlling the operation of the wire supply means so as to disconnect the said filler wire and the metal plate, the laser head At the end of welding, the irradiated portion of the laser beam is moved so as to include a portion where the filler wire enters the molten pool .

  According to the invention of claim 1 of the present application, the filler is formed behind the irradiated portion of the laser beam in the welding progress direction in the molten pool formed by irradiating the upper metal plate surface with the laser beam having a predetermined energy density. In laser welding in which a wire is supplied and two metal plates are laser-welded, the laser head is moved so that the filler wire can be irradiated with laser light at the end of welding, and the filler wire is moved from the laser head to the predetermined wire. Irradiate the laser beam with energy density lower than the energy density, and with the filler wire irradiated with the laser beam, pull the filler wire back in the direction opposite to the supply direction to the molten pool to separate the filler wire from the metal plate. .

  As a result, at the end of welding, only the filler wire can be melted and separated by the laser beam with reduced energy density, so that the metal solidified product of the welded portion adheres to the tip of the wire in a ball shape or the welded portion. It is possible to prevent the occurrence of poor welding such as formation of a hole, and the filler wire and the metal plate can be satisfactorily separated. In addition, since the laser beam is irradiated while pulling back the filler wire at the end of welding, the tip of the wire may be tapered when the wire is cut, but even in such a case, the wire is used for the next welding. It can be used effectively.

Further, since the irradiated portion of the record Za light moves the laser head to include a penetration portion of the molten pool of the filler wire can be more concretely realizing the effect.

Further, according to the invention according to claim 2 of the present application, the laser head is translated or rotated to the filler wire side, so that the laser head can be moved using a relatively simple device, The effect can be obtained effectively.

Furthermore, according to the invention of claim 3 of the present application, the laser welding apparatus can obtain the same operations and effects as those of the invention of claim 1 of the present application.

It is a principal part external view of the laser welding apparatus which concerns on embodiment of this invention. It is a control system figure of the welding apparatus. (A): It is a top view which shows the laser beam irradiated part of a metal plate in the regular welding, and the state of the vicinity. (B): It is XX sectional drawing of (a) figure. It is a time chart which shows the control at the time of completion | finish of welding. It is explanatory drawing of the 1st step of control at the time of completion | finish of regular welding and completion | finish of welding. It is explanatory drawing of the 2nd step of control at the time of completion | finish of welding, and a 3rd step.

  Hereinafter, a laser welding method and a laser welding apparatus according to embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows a main part of a laser welding apparatus 1 according to an embodiment of the present invention. The laser welding apparatus 1 is a laser head 10 that irradiates a laser beam A and a wire supply unit that supplies a filler wire B. 2 and the heating device 30 for the filler wire B. The two flat metal plates W1 and W2 stacked one above the other are irradiated with the laser beam A from above, and the upper side The heated filler wire B is supplied to the vicinity of the laser beam irradiated part x in the metal plate W1.

  Here, the metal plates W1 and W2 are fixed in a state of being overlapped by the clamp device 2, but between the metal plates W1 and W2, as shown in an exaggerated manner, a gap w caused by surface accuracy is shown. Has occurred.

  The laser head 10 and the wire supply device 20 are attached to the base plate 4 fixed to the arm 3a of the welding robot 3, and by the movement of the arm 3a, the metal plate W1 and W2 are moved in the welding direction indicated by the arrow a. The upper and lower metal plates W1 and W2 are moved to a predetermined welding path by moving and moving the irradiated portion x of the laser beam A and the supply position y of the filler wire B to the upper surface of the upper metal plate W1 in the same direction a. It can be welded along.

  The laser head 10 is configured by using, for example, a high-power laser such as a YAG laser or a carbon dioxide gas laser, and controls the laser output and laser light A by moving the built-in optical member 12 (see FIGS. 5 and 6). It is possible to control the focal position. As described above, the laser head 10 is attached to the base plate 4. More specifically, the laser head 10 can be rotated with respect to the base plate 4 by the laser head rotation drive mechanism 12 (see FIG. 2). A rotating shaft 11 is attached, and the laser head 10 is fixedly attached to the rotating shaft 11. Thereby, by controlling the operation of the laser head rotation drive mechanism 12, it is possible to control the irradiated portion x of the laser light A emitted from the laser head 10.

  The wire supply device 20 includes a wire supply unit 21 and a wire supply nozzle 22 disposed behind the laser head 10 in the welding progress direction. By the wire supply motor 23 (see FIG. 2) in the wire supply unit 21. The filler wire B is fed out from the wire roll 24 around which the filler wire B is wound, passed through the wire supply nozzle 22, and supplied to a predetermined position on the upper surface of the upper metal plate W1 at a predetermined angle. The wire supply motor 23 can control the rotation speed and the rotation direction, whereby the wire supply device 20 is configured so that the supply amount of the filler wire B can be adjusted, and the filler wire B is supplied from the wire roll 24. The filler wire B can be pulled back to the wire roll 24 so as to be supplied.

  The wire heating device 30 heats the wire B with Joule heat generated by energizing the filler wire B. The heating power device 31 and the nozzle-side cable 32 that connects the heating power device 31 and the wire supply nozzle 22. And a clamp-side cable 33 that connects the heating power supply device 31 and the clamp device 2.

  When a voltage is applied to the filler wire B held in the wire supply nozzle 22 via the nozzle side cable 32 and the wire supply nozzle 22, the clamp side cable is in a state where the filler wire B is in contact with the upper metal plate W1. 33, the heating power supply device 31 and the filler wire B are electrically connected via the clamp device 2 and the upper metal plate W1, so that the filler wire B extends from the voltage application position in the wire supply nozzle 22 to the tip. It is energized in the range, and the range is heated by Joule heat.

  The laser welding apparatus 1 also has a control unit 40. As shown in FIG. 2, the laser output of the laser head 10 and the focal position of the laser light A are controlled by the control signal from the control unit 40, and the wire supply apparatus. 20, control of the rotational speed and direction of the wire supply motor 23, control of the laser head rotation drive mechanism 12 that rotates and moves the laser head 10, control of voltage application to the filler wire B by the wire heating device 30, and welding robot 3 and the like are performed.

  At the time of steady welding, the focus of the laser beam A is controlled by the control unit 40 to a focus state on the surface of the upper metal plate W1, that is, a state where energy is most efficiently transmitted to the upper metal plate W1, As shown in FIG. 1, the laser head 10 is controlled so that the laser beam A can be irradiated to the upper metal plate W1 in a substantially vertical direction. The output of the laser beam A, the feeding speed of the filler wire B, the current value for heating, the moving speed (welding speed) of the robot arm 3a, etc. are appropriately set.

  Thereby, at the time of steady welding, with the movement of the robot arm 3a, both the metal plates W1 and W2 are welded along a predetermined welding path.

  Here, the state at the time of steady welding will be described. As shown in FIG. 3, the upper metal plate W1 of the two flat plate-like metal plates W1 and W2 overlapped with each other in a state where the gap w is generated. The upper surface is irradiated with laser light A having a predetermined energy density to melt at least the laser light irradiated portion x of the upper metal plate W1, and the molten metal Wb is stored in the molten pool WB. W1 is formed from the upper surface to the lower surface. In the present embodiment, the irradiated portion x of the laser beam A irradiated with the laser beam A during steady welding causes the metal to be in a plasma state by the laser beam A, and the keyhole Wa is formed by pushing the molten metal Wb around by the pressure. It is formed. Then, by moving the laser beam A in the welding progress direction a, the molten pool WB is formed on the rear side in the welding progress direction with respect to the irradiated portion x of the laser beam A.

  In parallel with this, the filler wire B that has been heated in advance by energization enters the weld pool WB with a predetermined distance z behind the irradiated portion x of the laser light A in the welding progress direction. The molten metal in the molten pool WB in the upper metal plate W1 is supplied to the molten pool WB and the end of the filler wire B is melted by heating by energization and the heat of the molten metal Wb stored in the molten pool WB. Increase the amount.

  Thereby, the molten metal Wb into the gap w between the upper and lower metal plates W1 and W2 due to the increased weight of the molten metal or the pressing force f when the end of the filler wire B enters the molten pool WB. The upper metal plate W1 and the lower metal plate W2 are connected by the molten metal Wb. And the molten metal Wb of the molten pool WB solidifies, and the welding part WC of a non-molten state will be formed.

  As described above, in the laser welding in which the two flat metal plates W1 and W2 overlapped with each other while supplying the filler wire B to the molten pool WB at the time of steady welding are performed as described above. Since the filler wire B is supplied to the molten pool WB, even when the filler wire B is pulled back at the end of welding, the molten metal Wb of the molten pool WB is fixed to the welded portion WC formed by solidification. If pulled apart, the metal solidified product of the welded portion WC adheres to the tip of the wire B in a ball shape or a weld failure occurs such that a hole is formed in the welded portion WC.

  Therefore, at the end of welding, in order to cut off the filler wire B from the metal plates W1 and W2, the control unit 40 controls the laser head 10 and the wire supply device 20 differently from those during steady welding. Next, the control at the end of welding will be described with reference to the time chart of FIG. 4 and the state explanatory diagrams of the steps of FIGS. 5 and 6.

  As described above, during steady welding, the focal point is focused on the upper surface of the metal plate W1 so that energy is transferred from the laser head 10 to the upper metal plate W1 in a focused state, that is, energy is most efficiently transmitted to the upper metal plate W1. In the set state, the laser beam A having a predetermined energy density is irradiated to melt at least the upper metal plate W1 to form a molten pool WB in which the molten metal Wb is stored, and the laser beam in the molten pool WB The filler wire B is supplied to the rear side in the welding progress direction from the irradiated portion x of A. A voltage is applied to the filler wire B, and the filler wire B is supplied to the molten pool Wb while being heated by energization. Thereby, the two metal plates W1 and W2 are laser-welded along a predetermined welding path while supplying the filler wire B to the molten pool WB.

  Then, when laser welding along a predetermined welding path is performed and the steady welding is finished, the irradiation of the laser beam A and the supply of the filler wire B to the molten pool WB are stopped, and the filler wire B is supplied to the filler wire B. The voltage application and the movement of the robot arm 3a are stopped. At the end of the steady welding, as shown in FIG. 5A, the filler wire B is supplied to the molten pool WB, and when the laser head 10 irradiates the laser beam A from the laser head 10, the filler wire B is supplied. It is controlled to a position where it is not irradiated.

  In the present embodiment, at the end of welding, first, as a first step, the movement of the laser head 10 by the laser head rotation drive mechanism 12 is controlled, and the laser head 10 is placed on the filler wire B side, that is, on the rear side in the welding progress direction. It is rotated by a predetermined angle, and is rotated clockwise as shown in FIG. At this time, the laser head 10 can more specifically irradiate the filler wire B with the laser beam A so that the irradiated portion x of the laser beam A has a portion of the filler wire B entering the molten pool WB. Rotated to include. In the present embodiment, the optical axis AC of the laser head 10 is moved so as to coincide with the portion where the filler wire B enters the molten pool WB.

  Next, as a second step, as shown in FIG. 6A, the operation of the laser head 10 is controlled, the optical member 12 of the laser head 10 is moved along the optical axis AC, and the laser head is moved to the filler wire B. When the laser beam A is irradiated from 10, the defocused state at the position where the filler wire B is irradiated, that is, the position where the filler wire B is irradiated is shifted from the position where energy is most efficiently transmitted. Move the focus to. Thereby, when the laser beam A is irradiated from the laser head 10 to the filler wire B, it is possible to irradiate the laser beam having an energy density lower than the predetermined energy density at the time of steady welding.

  Then, the laser beam A is irradiated from the laser head 10 to the filler wire B with a lower energy density than the predetermined energy density during steady welding. In the first step, the laser head 10 is moved so that its optical axis AC coincides with the portion where the filler wire B enters the molten pool WB, and when the laser beam A is irradiated, the irradiated portion x of the laser beam A is irradiated. Is moved so as to include the portion of the filler wire B that enters the molten pool WB, the filler wire B is irradiated with the laser beam A at the portion of the molten wire WB that enters. In FIG. 4, the energy of the laser beam A irradiated to the surface of the upper metal plate W1 during steady welding is represented as “HI”, and the laser beam irradiated to the filler wire B in the second step and the third step. The energy of A is expressed as “LOW”.

  Next, as a third step, as shown in FIG. 6B, the operation of the wire supply motor 23 of the wire supply device 20 is controlled in a state where the laser beam A is irradiated to the filler wire B in the second step. The filler wire B is pulled back to the wire reel 24 in the direction opposite to the supply direction to the molten pool WB, and the filler wire B and the metal plates W1 and W2 are separated. The filler wire B is pulled back while being irradiated with the laser beam A having a reduced energy density at the portion entering the molten pool WB, and blown by the laser beam A in the vicinity of the upper surface of the upper metal plate W1. The metal plates W1 and W2 can be separated satisfactorily.

  The laser welding apparatus 1 according to the present embodiment is also provided with an imaging apparatus (not shown) that images the vicinity of the portion where the filler wire B enters the molten pool WB. The laser welding apparatus 1 is an image captured by the imaging apparatus. It is possible to detect whether or not the filler wire B is separated from the metal plates W1 and W2 by image processing. In FIG. 4, the filler wire B and the metal plates W1 and W2 are separated. This time is expressed as t1. Then, after the filler wire B is separated from the metal plates W1 and W2, the filler wire B is pulled back until time t2 so that the filler wire B is pulled back to a predetermined position.

  On the other hand, the irradiation of the laser beam A emitted from the laser head 10 is stopped at a time t3 when a predetermined time has elapsed after the filler wire B is separated from the metal plates W1 and W2 at the time t1. Thereby, even when the filler wire B is melted and a part of the filler wire B remains on the metal plates W1 and W2, the filler wire B can be melted, and the unmelted wire B becomes the metal plate W1, It is possible to prevent remaining in W2.

  After the third step, for the next welding process, the laser head 10 is moved to the state at the time of steady welding, that is, rotated and moved forward in the welding progress direction which is the opposite side to the filler wire 10 side. The optical member 12 of the laser head 10 is moved to the state during steady welding, and then the robot arm 3a is moved to a predetermined position for the next welding process.

  In this embodiment, in the first step, the laser head B is rotated and moved toward the filler wire B so that the laser beam A can be applied to the filler wire B. However, the laser head 10 is moved relative to the base plate 4. It is also possible to make the laser head 10 parallel to the filler wire B side, that is, backward in the welding direction so that the laser beam A can be irradiated to the filler wire B. .

  As described above, in this embodiment, the welding progress direction of the weld pool WB formed by irradiating the surface of the upper metal plate W1 with the laser beam A having a predetermined energy density is higher than the irradiated portion x of the laser beam A. In the laser welding in which the filler wire B is supplied to the rear and the two metal plates W1 and W2 are laser welded, the laser head 10 is moved so that the filler wire B can be irradiated with the laser beam A at the end of the welding. The filler wire B is irradiated from the laser head 10 with the laser beam A having an energy density lower than the predetermined energy density, and the filler wire B is irradiated with the laser beam A, and the filler wire B is transferred to the molten pool WB. Then, the filler wire B and the metal plates W1, W2 are separated from each other.

  Thereby, at the end of welding, only the filler wire B can be melted and separated by the laser beam A with reduced energy density, so that the solidified metal of the welded portion WC adheres to the tip of the wire B in a ball shape. It is possible to prevent a welding failure such as a hole being formed in the welded portion WC, and the filler wire B and the metal plates W1 and W2 can be well separated. Moreover, since laser beam A is irradiated while pulling back filler wire B at the end of welding, the tip of wire B may be tapered when wire B is cut off. Can be effectively used for the next welding.

  In the first step, since the laser head 10 is translated or rotated to the filler wire B side, it is possible to move the laser head 10 using a relatively simple device, and the above effect is effectively obtained. Can be obtained.

  In the above-described embodiment, the optical member 12 of the laser head 10 is moved along the optical axis AC, and the laser beam A is irradiated in a focused state on the upper surface of the upper metal plate W1 at the time of steady welding. In the step and the third step, the filler wire B is irradiated with the laser beam A in a defocused state, and the laser beam A having a lower energy density than that during steady welding is irradiated to the filler wire B at the end of welding. By changing the output of the laser beam A emitted from the laser head 10, it is possible to irradiate the filler wire B with the laser beam A having a lower energy density than during steady welding at the end of welding.

  In this case, at the end of welding, the laser beam A whose output is lower than that during steady welding is irradiated, so that only the filler wire B can be melted and separated from the metal plates W1 and W2, and the laser beam A can be used. It can prevent that metal plate W1, W2 is further fuse | melted and a hole part is formed.

  5 and 6, the weld pool WB is shown in the same shape in the first step, the second step, and the third step at the end of welding, but when the irradiation of the laser beam A is stopped at the end of the steady welding. From this, the molten pool WB is solidified from its surroundings. Even in such a case, in the laser welding according to the present embodiment, only the filler wire B can be melted and separated by the laser beam A having a reduced energy density. Therefore, the filler wire B and the metal plates W1 and W2 can be separated satisfactorily.

  The present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes are possible without departing from the spirit of the present invention.

  As described above, the present invention can satisfactorily separate the filler wire and the metal plate at the end of welding when laser welding is performed on two metal plates that are stacked one above the other while supplying the filler wire to the molten pool. Therefore, there is a possibility of being widely used, for example, in the automobile industry where this type of welding is performed.

DESCRIPTION OF SYMBOLS 1 Laser welding apparatus 10 Laser head 20 Wire supply apparatus 40 Control unit A Laser beam B Filler wire W1 Upper metal plate W2 Lower metal plate WB Molten pool Wb Molten metal WC Welding part w Clearance x Laser beam irradiated part

Claims (3)

A laser beam having a predetermined energy density is irradiated on the surface of the upper metal plate among the two flat plate-like metal plates in which a gap is formed between the opposing surfaces in a state where they are vertically stacked, A molten pool is formed by melting and storing molten metal, and a filler wire is supplied to the rear of the laser beam irradiated portion in the molten pool in the welding progress direction to laser weld two metal plates. Laser welding method, at the end of welding,
A first step of moving a laser head for irradiating laser light so that the filler wire can be irradiated with laser light;
A second step of irradiating the filler wire with laser light having an energy density lower than the predetermined energy density from the laser head;
A third step of pulling back the filler wire in a direction opposite to the supply direction to the molten pool while irradiating the laser beam on the filler wire, and separating the filler wire and the metal plate;
Equipped with a,
In the first step, the laser head is moved so that the irradiated portion of the laser light includes a portion of the filler wire entering the molten pool,
A laser welding method characterized by that. In the laser welding method according to claim 1 ,
In the first step, the laser head is translated or rotated to the filler wire side,
A laser welding method characterized by that. A laser beam having a predetermined energy density is irradiated on the surface of the upper metal plate among the two flat plate-like metal plates in which a gap is formed between the opposing surfaces in a state where they are vertically stacked, A laser head that forms a molten pool in which molten metal is stored by melting and a filler wire that is configured to be able to supply a filler wire to the rear of the laser beam irradiated portion in the welding pool in the welding progress direction and the filler wire Wire supply means configured to be retractable in a direction opposite to the supply direction to the molten pool, and a laser welding apparatus for laser welding two metal plates while supplying filler wire to the molten pool ,
At the end of welding, the movement of the laser head is controlled so that the filler wire can be irradiated with laser light, and laser light having an energy density lower than the predetermined energy density is applied to the filler wire from the laser head. The operation of the laser head is controlled so as to irradiate, and the filler wire is pulled back in the direction opposite to the supply direction to the molten pool in a state where the filler wire is irradiated with the laser beam, and the filler wire, the metal plate, further example Bei control means for controlling the operation of the wire supply means so as to disconnect the,
The laser head is moved at the end of welding so that the irradiated portion of the laser beam includes a portion of the filler wire entering the molten pool,
A laser welding apparatus characterized by that.

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