JP5391953B2 - 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 as a welding method for two flat 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. The laser beam irradiated portions of the upper and lower metal plates are melted to form a linear weld bead.

  In that case, since the opposing surfaces of the two metal plates are generally not completely flat, a gap may be formed between the two metal plates, and the size of the gap is also uniform on the welding path. As a result, for example, in a place where the gap is large, the molten metal of the upper metal plate does not hang down until it contacts the lower metal plate beyond the gap, and a welding failure may occur in which the upper and lower metal plates are not connected. It was.

  To solve this problem, the filler wire is supplied to the irradiated portion of the laser beam so that the end follows the movement, and the filler wire is melted together with the metal plate to increase the molten metal. It is known that the molten metal can easily hang down to contact with the lower metal plate across the gap, thereby preventing welding failure in which the upper and lower metal plates are not connected.

  In that case, in order to melt the filler wire surely, in Patent Document 1, as a method of laser welding the butt portion of the two metal members, the end of the filler wire is supplied to the irradiated portion of the laser beam, The thing which melt | dissolved the wire and the to-be-welded metal member simultaneously is disclosed.

  In addition, when supplying a filler wire to a laser beam irradiation site, it is necessary to appropriately set the supply start timing of the wire at the start of welding and the irradiation start timing of the laser beam. By applying a voltage to the filler wire in advance, it is configured so that energization is started when the tip of the wire comes into contact with the metal member to be welded, and irradiation of laser light is started with the energization start time as a reference The timing is set.

JP 2005-81403 A

  By the way, when the filler wire and the metal member to be welded are simultaneously melted by laser light as in the method disclosed in Patent Document 1, the amount of the molten metal becomes excessive, and the molten metal swells on the surface of the welded portion. There arises a problem that a so-called surplus portion solidified in a state is generated, and the appearance is deteriorated.

  Moreover, when the method of patent document 1 is applied when welding the two metal plates piled up and down, when there exists a clearance gap between both metal plates, the molten metal of a metal plate and a filler wire will adhere to an upper metal plate. There is a possibility that a problem arises in that the upper and lower metal plates are not connected to each other because the surface tension stays in the hole that penetrates in the upper and lower portions, and does not hang down to the lower metal plate beyond the gap.

  Therefore, when two metal plates stacked one above the other are welded using a filler wire, the molten metal is formed behind the upper metal plate in the welding progress direction, that is, formed by irradiation with laser light. The end of the filler wire heated in advance by energization is inserted into the portion where the molten metal is stored in a pond shape in the hole that penetrates up and down, and by the heating by this energization and the heat of the molten metal stored in the molten pool The wire is surely melted and the force of pushing the molten metal in the molten pool downward is generated by the entry of the filler wire, thereby ensuring a sufficient amount of molten metal and actively dripping it. It has been considered that the upper and lower metal plates are reliably connected without generating extra portions.

  However, in this way, in the method in which the filler wire that is energized and heated enters the molten pool formed behind the welding progress direction, the wire is formed at the start of welding where the formation of the molten pool and heating of the filler wire by energization are not sufficient. Is not reliably melted and there is a gap between the upper and lower metal plates, the two metal plates are not connected well, or a part of the filler wire that is insufficiently melted remains on the surface of the metal plate and the appearance deteriorates There is a risk of poor welding such as welding.

  Then, this invention makes it a subject to prevent the above welding defects at the time of a welding start, when connecting the two metal plates piled up and down by laser welding using a filler wire.

  In order to solve the above-described problems, the present invention is configured as follows.

  First, the invention according to claim 1 of the present application is directed to irradiating laser light from above on two flat metal plates in which a gap is formed between opposing surfaces in a state where they are vertically stacked. A molten pool in which molten metal is stored in a hole penetrating up and down behind the laser beam irradiation site of the upper metal plate by moving light relatively along a predetermined welding path. And a filler wire heated in advance and energized at a position spaced a predetermined distance behind the laser beam irradiated site in the molten pool, and at the start of welding, the upper metal plate A first step of forming a molten hole penetrating vertically in the upper metal plate by irradiating the welding start position with laser light to melt the irradiated portion, and a fusion hole formed by the first step A second step of setting the position of the wire supply means to the front side in the welding progress direction from the position when the filler wire is supplied to the position behind the laser beam irradiated part so that the end of the filler wire enters into Irradiating the melt hole with laser light whose energy density is lower than that in the first step, and supplying a filler wire to which voltage is applied from the wire supply means whose position is set in the second step. A third step of causing the end portion to enter the molten hole portion and starting energization of the filler wire by contact between the wire and the upper metal plate at that time; and the wire supply means relative to the irradiated portion of the laser beam And the position of the wire supply means is set to the position when the filler wire is supplied to the position behind the laser light irradiated portion. And then increasing the energy density of the laser light, maintaining the positional relationship between the laser light irradiated part and the wire supply means, and supplying the filler wire from the wire supply means, And a fifth step of starting movement of the wire supply means along the welding path.

  In the invention of claim 2, in the invention of claim 1, in the third step, the energy density is lowered before the end of the filler wire enters the laser light irradiation range. Laser irradiation is started.

  According to a third aspect of the present invention, in the second aspect of the invention according to the first or second aspect, the end portion of the filler wire is in contact with the inner surface of the molten hole portion on the front side in the welding progress direction. The position of a wire supply means is set so that it may contact.

  Furthermore, the invention according to claim 4 is the invention according to any one of claims 1 to 3, in the fifth step, before the start of movement of the laser light and filler wire supply means, It is characterized by increasing the energy density of laser light.

  The invention according to claim 5 irradiates the laser beam from above while irradiating the two flat metal plates having a gap between the surfaces facing each other in a state where they are stacked one above the other. By moving relatively along a predetermined welding path, a molten pool is formed in which the molten metal is stored in a hole penetrating up and down behind the laser beam irradiation site of the upper metal plate. A laser irradiation means for performing a laser irradiation, a wire supply means for supplying a filler wire to a position spaced a predetermined distance rearward from the laser beam irradiated site in the molten pool, and a current heating means for energizing and heating the filler wire in advance At the start of welding, by controlling the laser irradiating means and the wire supplying means, first, the welding start position of the upper metal plate is irradiated with laser light. A melt hole that vertically penetrates the irradiation site is formed, and the filler wire is placed at the position behind the laser beam irradiation site so that the end of the filler wire enters the melt hole. Is set on the front side in the welding progress direction from the position when supplying the molten metal, and then the laser beam having a lower energy density than that when forming the molten hole is irradiated toward the molten hole and the wire is supplied. A voltage-applied filler wire is supplied from the means to cause the end portion to enter the melting hole, and the filler wire is energized by contact between the wire and the upper metal plate at that time, and the wire supply means Is set to the position when supplying the filler wire to the position behind the laser light irradiated site, and the energy density of the laser light is increased, Thereafter, the laser light and the wire supply means are started to move along the welding path while maintaining the positional relationship between the laser light irradiated portion and the wire supply means and supplying the filler wire from the wire supply means. It has a control means.

  Next, the effect of the present invention will be described.

  First, according to the first aspect of the invention, at the start of welding, first, in the first step, a laser beam is irradiated to the welding start position of the upper metal plate, and the molten hole that penetrates the irradiated site vertically. Part is formed. In that case, since the laser beam is irradiated in a state where it does not move relative to the metal plate, the molten hole can be reliably formed by appropriately setting the energy density, irradiation time, and the like. .

  Then, in the second to third steps, a filler wire to which a voltage is applied in advance is supplied toward the molten hole, and the wire is irradiated with the laser beam and heated by passing through the irradiation range of the laser beam. At the same time, when the end portion comes into contact with the upper metal plate, energization heating for the wire is started.

  At that time, since the energy density of the laser beam is lower than that in the steady welding in which welding is in progress after the start of welding, the filler wire is not completely melted and is in a semi-molten state, that is, between solid and liquid. It is in a state of being softened in a range where it does not fluidize, and starts to melt when electric heating is started. Further, since the energy density of the laser beam is not high, the upper metal plate in which the melting hole is formed will not be further melted.

  Thereafter, in the fourth step, the filler wire supply position is set to a position separated by a predetermined distance from the laser light irradiated portion, that is, a position at the time of steady welding, and in the fifth step, the energy density of the laser light is set. Is also increased to the density during steady welding. Then, steady welding is started by keeping the positional relationship between the irradiated portion of the laser beam and the supply position of the filler wire and moving them forward along a predetermined welding path.

  In this case, according to the present invention, since the filler wire has already started to melt, the wire is sufficiently melted immediately after the start of steady welding, so that the upper metal plate does not have a surging portion on the upper and lower surfaces. The gap between the metal plates is filled, and the two metal plates are securely connected.

  According to the invention of claim 2, when irradiating the laser beam whose energy density has been reduced in the third step, the irradiation is started before the filler wire enters the irradiation range of the laser beam. Therefore, the filler wire is irradiated with laser light at the same time that the end portion enters the irradiation range, and is reliably heated from the tip. Therefore, poor welding due to the occurrence of a location where the irradiation to the filler wire is delayed and the wire is insufficiently semi-melted is prevented.

  According to the invention described in claim 3, when the position of the wire supply means is set in the second step, the end portion of the filler wire comes into contact with the inner wall surface on the front side in the welding progress direction of the molten hole portion. Therefore, the tip of the filler wire is surely in contact with the upper metal plate, and energization heating is always started at a predetermined timing.

  According to the fourth aspect of the present invention, when the laser beam and filler wire supply means are started to move forward in the welding progress direction in the fifth step, the energy density of the laser beam is increased prior to the start of the movement. Therefore, steady welding is performed with laser light having a predetermined energy density immediately after the start of welding, and poor welding due to lack of energy of laser light immediately after the start of steady welding is prevented.

  And according to the laser welding apparatus which concerns on invention of Claim 5, the effect similar to the laser welding method of the said Claim 1 is acquired.

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 irradiation site | part of a metal plate in 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 a welding start. It is explanatory drawing of the 1st step of control at the time of a welding start. It is explanatory drawing of a 2nd step as well. It is explanatory drawing of a 3rd step as well. It is explanatory drawing of a 4th step as well. It is explanatory drawing of a 5th step.

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

  FIG. 1 shows a main part of a laser welding apparatus 1 according to the present embodiment. This laser welding apparatus 1 includes a laser head 10 that generates a laser beam A, a wire supply device 20 that supplies a filler wire B, With the heating device 30 for the filler wire B, the laser beam A is irradiated from above on the metal plates W1 and W2 stacked one above the other, and in the vicinity of the laser beam irradiated part x on the upper metal plate W1, The heated filler wire B is supplied.

  Here, the metal plates W1 and W2 are fixed in a state of being overlapped by the clamp device 2, but a gap w due to surface accuracy is shown between the metal plates W1 and W2 as exaggeratedly 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 the welding progress direction indicated by the arrow a with respect to the metal plates W1 and W2 by the movement of the arm 3a. The upper and lower metal plates W1 and W2 are moved along a predetermined path by moving the irradiated portion x of the laser beam A and the supply position y of the filler wire B with respect to the upper surface of the upper metal plate W1 in the same direction a. It is supposed to be welded.

  The laser head 10 is configured by using a high-power laser such as a YAG laser or a carbon dioxide gas laser, for example, and controls the laser output and laser light by moving the built-in optical member 11 (see FIG. 5 and the like). The focus position of A can be controlled.

  The wire supply device 20 includes a wire supply unit 21 and a wire supply nozzle 22 for setting the supply position and supply direction of the filler wire B, and a motor 23 in the wire supply unit 21 (see FIG. 2). Thus, the filler wire B is fed out from the wire roll 24, passes through the nozzle 22, and is supplied to a predetermined position on the upper surface of the upper metal plate W1 at a predetermined angle.

  Here, the wire supply nozzle 22 supplies the filler wire B to the laser beam A from the rear of the welding progress direction a, and moves the nozzle 22 back and forth along the same direction a. It is attached to the base plate 4 via the horizontal movement mechanism 25, and the positional relationship of the wire supply position y with respect to the laser beam irradiated portion x on the upper surface of the upper metal plate W1 can be controlled.

  Further, the wire heating device 30 heats the wire B with Joule heat generated by energizing the filler wire B, and connects the heating power supply device 31 to the power supply device 31 and the wire supply nozzle 22. It has a nozzle side cable 32 and a clamp side cable 33 for connecting the power supply device 31 and the clamp device 2.

  If a voltage is previously applied to the filler wire B held in the nozzle 22 via the nozzle-side cable 32 and the wire supply nozzle 22, the tip of the wire B comes into contact with the upper metal plate W1. The heating power supply device 31 and the filler wire B are electrically connected via the clamp-side cable 33, the clamp device 2 and the upper metal plate W1, so that the wire B is distal from the voltage application position in the nozzle 22. Is energized in the range up to and the range is heated by the 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 unit 40, and the wire is supplied. The operation of the wire supply motor 23 and the wire feed speed in the apparatus 20, the control of the horizontal movement mechanism 25 that horizontally moves the wire supply nozzle 22, the voltage application control to the filler wire B by the wire heating device 30, and the welding robot 3 And so on.

  At the time of steady welding after the start of welding, the focus of the laser beam A is controlled by the control unit 40 to a position where energy is most efficiently transmitted to the upper metal plate W1, and a horizontal movement mechanism. As shown in FIG. 1, the position of the wire supply nozzle 22 set by 25 is such that the wire supply position y on the upper surface of the upper metal plate W1 is a predetermined distance z behind the laser beam irradiation site x in the welding progress direction a. It is controlled so as to be separated from each other. 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 path.

  Here, the state of the welded part at the time of steady welding will be described. As shown in FIG. 3, the upper side of the two flat plate-like metal plates W1 and W2 with the gap w formed therebetween is formed. When the upper surface of the metal plate W1 is irradiated with the laser beam A and the laser beam A is moved in the welding progress direction a in this state, at least the laser beam irradiated portion x of the upper metal plate W1 is melted, and the metal plate W1 A hole Wa that penetrates up and down is formed. Then, the molten metal flows into the hole Wa, and a molten pool Wb in which the molten metal is stored in the hole Wa behind the laser beam irradiation site x in the welding progress direction a by the movement of the laser light A. Is formed.

  In parallel with this, the filler wire B heated by energization in advance is supplied so that the end portion enters the weld pool Wb at a predetermined distance z behind the laser beam irradiation site x in the welding progress direction. The end of the filler wire B is melted by heating by energization and the heat of the molten metal stored in the molten pool Wb, and the amount of molten metal in the molten pool Wb in the upper metal plate W1 is increased.

  As a result, the increased weight of the molten metal, the pressing force f when the end portion of the filler wire B enters the molten pool Wb, etc. cause the molten metal to enter the gap w between the upper and lower metal plates W1, W2. The entry is promoted, and the upper and lower metal plates W1 and W2 are connected when the molten metal entering the gap w is cured.

  By the way, at the time of steady welding, the filler wire B is energized in the range from the voltage application position in the wire supply nozzle 22 to the tip portion in contact with the upper metal plate W1, and therefore the end of the wire B that enters the molten pool Wb. The part is heated for a relatively long time until it moves from the voltage application position to the contact position with the metal plate W1, and is heated to a temperature at which it can be sufficiently melted by the heat of the molten metal in the molten pool Wb. Has been.

  However, at the start of welding, the filler wire B is not energized until the end portion comes into contact with the upper metal plate W1 after the supply is started, and comes into contact with the upper metal plate W1 in an unheated state. Further, the molten pool Wb is not sufficiently formed behind the welding progress direction a of the laser beam irradiated portion x. Therefore, even when the filler wire B is supplied to a predetermined position behind the irradiated portion x in a state where the laser beam A is irradiated to the welding start position on the upper surface of the upper metal plate W1, the wire B is not sufficiently melted. .

  As a result, at the welding start position, the molten metal is insufficient, and the molten metal does not enter the gap w between the upper and lower metal plates W1, W2, resulting in a disconnected portion between the two metal plates W1, W2, and the filler wire. There is a possibility that poor welding may occur, for example, a surplus portion is left on the upper surface of the upper metal plate W1 in a state where the end portion of B is not sufficiently melted.

  Therefore, in order to prevent poor welding at the start of welding, the control unit 40 performs control different from that during steady welding on the laser head 10 and the wire supply device 20. Control at the start of welding will be described with reference to the time chart of FIG. 4 and the state explanatory diagrams of the respective stages of FIGS.

  First, as a first step, the laser beam A is irradiated from the laser head 10 to the welding start position of the upper metal plate W1, and the irradiated portion x is melted, so that the upper metal plate W1 is irradiated as shown in FIG. A fusion hole Wc penetrating vertically is formed.

  At this time, the laser beam A is in a focused state, that is, in a state where the focal point is set at a predetermined position in the upper surface of the metal plate W1 or inside the metal plate so that energy is most efficiently transmitted to the upper metal plate W1. In addition, the laser output and the irradiation time of the laser beam A are set to values necessary for forming the molten hole portion Wc. As a result, a molten hole portion Wc penetrating vertically is formed in the upper metal plate W1 and the molten metal Wd generated during the formation of the molten hole portion Wc is exclusively formed on the upper surface of the lower metal plate W2 and the metal. It is stored in a recess formed in the plate W2.

  At this time, the wire supply nozzle 22 in the wire supply device 20 is set to a position where the filler wire B is supplied to the position at the time of steady welding shown in FIGS. 1 and 3. At this time, the filler wire B is applied with a voltage at a portion held by the nozzle 22 but is not energized because the tip is not in contact with the upper metal plate W1.

  Next, as a second step, the horizontal movement mechanism 25 in the wire supply device 20 is operated to move the wire supply nozzle 22 by a predetermined distance in the welding progress direction a. As shown in FIG. If the wire B is supplied, the end of the wire B is set to a position where it abuts the inner surface of the molten hole Wc formed in the upper metal plate W1 on the front side in the welding progress direction.

  In parallel with this, after stopping the irradiation of the laser beam A, the optical member 11 of the laser head 10 is moved along the optical axis, and when the laser beam A is irradiated, the upper metal plate W1 and filler are used. The focal point is moved so as to be in a defocused state at the position where the wire B is irradiated.

  Next, as a third step, as shown in FIG. 7, the laser beam A is irradiated from the laser head 10 and the motor 23 of the wire supply device 20 is operated to start supplying the filler wire B.

  In that case, as described above, when the filler wire B is supplied, the wire supply nozzle 22 has an end portion on the inner surface on the front side in the welding progress direction of the fusion hole Wc formed in the upper metal plate W1. Since it is set to a position where it comes into contact, and the focal point of the laser beam A is set to be in a defocused state at the position where the laser beam A is irradiated, the filler supply nozzle 22 as shown in FIG. The filler wire B that has been fed out is irradiated with the laser beam A in a defocused state, and then comes into contact with the inner surface on the front side in the welding progress direction of the molten hole portion Wc formed in the upper metal plate W1.

  As a result, energization to the filler wire B is started as indicated by reference numeral b in FIG. 4. The wire B is shaped by receiving irradiation of the laser light A having a reduced energy density in the defocused state. While being held in a semi-molten state, heating by energization is started to start melting. At this time, since the energy density of the laser beam A is low, the upper metal plate W1 is not further melted by the laser beam A, and the molten hole portion Wc is held as it is.

  In this third step, when the laser beam A is irradiated and the supply of the filler wire B is started, the irradiation is started before the wire B enters the irradiation range of the laser beam A. If controlled, the filler wire B is irradiated with laser light at the same time as its end enters the irradiation range, and is reliably heated from the tip.

  Next, as a fourth step, as shown in FIG. 8, after the irradiation of the laser beam A is stopped, the focal point of the laser beam A is set to the same focus state as the first step in the second step. The optical member 11 of the laser head 10 is moved along the optical axis in the direction opposite to the movement of.

  In parallel with this, the wire supply nozzle 22 is moved by a horizontal movement mechanism 25 in the wire feed device 20 in a direction opposite to the welding progress direction a by a predetermined distance, and the filler wire B is supplied from the nozzle 22. The position of the nozzle 22 is such that the supply position of the end of B is a position behind the laser beam irradiated part x on the upper surface of the upper metal plate W1 by a predetermined distance z, that is, a position at the time of the above-described steady welding. Set.

  In that case, the tip of the filler wire B is separated from the inner surface of the molten hole portion Wc on the front side in the welding progress direction, but the melting of the wire B is started in the third step, and the molten hole portion Wc Since the molten metal Wd is being stored in the state of being combined with the molten metal accumulated on the lower metal plate W2 in the step, the tip of the wire B comes into contact with the molten metal Wd, so that reference numeral c in FIG. As shown by, energization is maintained.

  Then, as a fifth step, if the laser beam A is irradiated from the laser head 10, the laser beam A in a focused state with a high energy density is irradiated onto the molten hole portion Wc. The molten metal Wd is already stored in the portion Wc, and the end of the filler wire B is heated by the molten metal Wd and the current heating is continued. Therefore, the wire B is further melted and is shown in FIG. Thus, the molten pool We centering on the laser beam irradiation site | part x is formed.

  In this state, the movement of the robot arm 3a is started, the positional relationship between the laser beam irradiated portion x and the wire supply position y is maintained, and when these are started to move in the welding progress direction a, the molten pool We 3 becomes a molten pool Wb shown in FIG. 3 and shifts to a steady welding state. Thereafter, steady welding is performed along a predetermined path.

  Welding is started as described above. However, since the filler wire is in a semi-molten state at the start of steady welding, it is sufficiently melted immediately after the start of steady welding. Thus, without forming a surplus portion on the surface of the upper metal plate, the gap w between the upper and lower metal plates W1, W2 is filled, and the two metal plates W1, W2 are reliably connected.

  In the above embodiment, in the second step, the wire supply nozzle 22 is moved from the position at the time of steady welding to the position on the front side in the welding progress direction. In this case, the movement of the wire supply nozzle 22 in the second step can be omitted.

  Further, in the fourth step, the wire supply nozzle 22 is moved from the front side position to the rear side normal welding position, but this movement is omitted and the laser head 10 is moved by a predetermined amount in the welding progress direction. Thus, it is possible to set the positional relationship between the nozzle 22 and the laser light irradiated portion to the positional relationship during steady welding and to proceed to steady welding as it is.

  As described above, the present invention can satisfactorily perform welding at the start of welding when laser welding two metal plates stacked one above the other using a filler wire. For example, in the automobile industry.

1 Laser welding equipment 10 Laser head (laser irradiation means)
20 Wire supply device 22 Wire supply nozzle (wire supply means)
30 Wire heating device (wire heating means)
A Laser beam B Filler wire W1 Upper metal plate W2 Lower metal plate Wb, We Molten pool Wc Molten hole w Gap x Laser beam irradiated portion y Wire supply position

Claims (5)

  While irradiating laser light from above on two flat metal plates with a gap between the opposing surfaces in a state where they are stacked one above the other, the laser light is relatively moved along a predetermined welding path As a result, a molten pool in which molten metal is stored in a hole penetrating vertically is formed behind the laser beam irradiation site of the upper metal plate, and the laser beam irradiation in the molten pool is performed. A laser welding method in which a filler wire heated in advance is supplied to a position spaced a predetermined distance behind the irradiated part, and at the start of welding, a laser beam is irradiated to the welding start position of the upper metal plate to be irradiated. By melting the portion, the first step of forming a molten hole portion penetrating vertically in the upper metal plate, and the end of the filler wire enters the molten hole portion formed by the first step. In addition, the second step of setting the position of the wire supply means to the front side in the welding progress direction from the position when the filler wire is supplied to the position behind the laser light irradiated portion, and the energy density is lower than that of the first step. The irradiated laser beam is irradiated toward the molten hole, and a filler wire applied with a voltage is supplied from the wire supply means whose position is set in the second step so that the end portion enters the molten hole. A third step of starting energization of the filler wire by contact between the wire and the upper metal plate at that time, and moving the wire supply means relative to the laser light irradiated portion; A fourth step of setting the position to a position at which the filler wire is supplied to the position behind the irradiated portion of the laser beam, and then the energy of the laser beam The laser beam and the wire supply means are supplied to the welding path while the filler wire is supplied from the wire supply means while maintaining the positional relationship between the laser light irradiated portion and the wire supply means. And a fifth step of starting movement along the laser welding method.   2. The laser welding method according to claim 1, wherein, in the third step, before the end of the filler wire enters the laser light irradiation range, irradiation with laser light with a reduced energy density is started. 3. .   In the second step, the position of the wire supply means is set so that the end portion of the filler wire is in contact with the inner surface of the molten hole portion on the front side in the welding progress direction. The laser welding method as described.   4. The laser according to claim 1, wherein, in the fifth step, the energy density of the laser light is increased before the movement of the laser light and the filler wire supply unit is started. 5. Welding method.   While irradiating the laser beam to the surface of the upper metal plate of the two flat metal plates in which a gap is formed between the opposing surfaces in a state where they are stacked one above the other, the laser beam is applied to a predetermined welding path. A laser irradiation means for forming a molten pool in which molten metal is stored in a hole portion penetrating vertically above and below the laser beam irradiation site of the upper metal plate and its welding progress direction A laser welding apparatus comprising: a wire supply means for supplying a filler wire to a position separated by a predetermined distance from a laser light irradiated site in the molten pool; and an energization heating means for energizing and heating the filler wire in advance, At the start of welding, the laser beam irradiating means is controlled so that a molten hole penetrating vertically is formed at the welding start position of the upper metal plate. The position of the wire supply means is controlled so that the end of the laser beam is supplied, and then the laser light irradiation means irradiates a laser beam with reduced energy density, and the wire supply means supplies the wire. By causing the end portion to enter the molten hole portion, the wire is brought into contact with the upper metal plate to start energization heating by the energization heating means, and then becomes a position for supplying the filler wire to the separation position. As described above, the position of the wire supply means relative to the laser light irradiated portion is moved relatively, and in this state, the energy density of the laser light irradiated by the laser light irradiation means is increased, and the laser light irradiation means and the wire supply And a control means for starting movement of the means along the welding path.

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