JP2007105754A - Laser irradiation arc welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser irradiation arc welding method capable of obtaining uniform and sufficient penetration depth, forming welding bead with large joining strength while bridging between upper and lower plates, and enhancing fatigue strength in fillet welding for a lap joint with a gap. <P>SOLUTION: The laser irradiation arc welding method includes: irradiating a fillet welding portion for a lap joint having a gap between the upper and lower plates with laser beam; and supplying an AC power with a present EN ratio between welding wire and lap joint to perform consumable electrode gas shielded arc welding. In the laser irradiation arc welding method, laser beam is irradiated such that: as the length of the gap increases, the diameter of a beam spot by the laser beam increases; laser output increases corresponding to the diameter of the beam spot; and the lower plate is irradiated with the laser beam, so that the outline of the beam spot nearly agrees with a welding line where the lower end part of the upper plate overlaps with the surface of the lower plate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improved laser irradiation arc welding method for irradiating a workpiece with a laser beam from a laser torch and performing consumable electrode gas shield arc welding.

[Prior art 1]
Laser welding using a carbon dioxide laser, YAG laser, semiconductor laser, or the like is a heat source with a high energy density, and therefore, high-speed welding exceeding 2 [m / min] is possible. However, in this laser welding, when a lap joint, a butt joint, or the like is welded, when there is a gap in the joint part, the beam spot diameter of the laser irradiation part is small, so the amount of molten metal is small and welding is performed while filling the gap. It is difficult. Therefore, in laser welding, since it is necessary to make the joint part of a to-be-welded object a state without a gap, the practical application range was very limited.

  As one method for solving the above-mentioned problems of laser welding, a laser irradiation DC arc welding method using both laser irradiation and consumable electrode gas shield DC arc welding has been proposed. This welding method secures high-speed weldability by a high energy density heat source formed by the laser irradiation described above, and melts the joint portion widely by a wide heat source formed by a DC arc. At the same time, by melting the welding wire and filling the gap portion, good high-speed welding can be performed even on the joint portion having the gap.

  FIG. 8 is a view showing a welding apparatus for carrying out a general laser irradiation DC arc welding method, and FIG. 9 is a view showing a general laser irradiation arc welding head. 8 and 9 show a case where a YAG laser or a semiconductor laser and a consumable electrode gas shield arc welding apparatus are used.

  In FIG. 8, the DC arc welding power supply device 1 controls the rotation of the welding wire feeding roll 3 of the welding wire feeder 2 so that the welding wire 4 is a welding torch body 6 of a welding torch 5 (see FIG. 9). Sent through. Further, the DC arc welding power supply device 1 generates an arc 8 by supplying electric power between a power feed tip provided in the welding torch body 6 and the workpiece 7.

  The laser beam 10 output from the laser oscillator 9 is transmitted to the condenser lens optical system 13 (see FIG. 9) of the laser torch 12 through the optical fiber 11, and is sent to the workpiece 7 by the condenser lens optical system 13. It is focused and irradiated so as to produce a focal point. The position where the laser beam 10 is irradiated is a position having an appropriate distance from the generation part of the arc 8 of the workpiece 7.

  As described above, the user-irradiated direct current arc welding method of the prior art 1 enables high-speed welding to a welded joint having a gap. However, since the allowable range of the gap is as small as about 0.3 mm or less, the practical application range of this welding method has been considerably limited. Accordingly, an AC arc welding method, which is a welding method that generally has a large allowable gap range, will be described as Prior Art 2.

[Prior Art 2]
FIG. 10 is a view showing a welding apparatus for carrying out the AC arc welding method of the prior art 2. As shown in FIG. In the figure, an AC arc welding power source 14 controls the rotation of the welding wire feeding roll 3 of the welding wire feeder 2 so that the welding wire 4 is fed through the welding torch body of the welding torch 5. Further, the AC arc welding power source 14 supplies power between the power supply tip provided in the welding torch body of the welding torch 5 and the work piece 7 with electric power that alternately repeats the electrode positive polarity and the electrode negative polarity. As will be described later with reference to FIG. 11, by applying a re-ignition voltage Vrs at the time of polarity switching, the arc 8 is re-ignited to generate an AC arc. Here, the case where alternating current arc welding is alternating current pulse arc welding is illustrated.

  FIG. 11 is a diagram showing an output waveform of the AC arc welding power source 14 described above. FIG. 11 (A) shows a time change of the welding current Iw, and FIG. 11 (B) shows a time change of the welding voltage Vw. Show. Hereinafter, a description will be given with reference to FIG.

(1) Period from time t1 to t2 (peak period Tp)
During this period, the electrode has a positive polarity EP in which the welding wire serves as an anode and the work piece serves as a cathode, and as shown in FIG. The peak current Ip is energized. Further, as shown in FIG. 5B, the welding voltage Vw during this period is the peak voltage Vp corresponding to the energization of the peak current Ip.

(2) Period from time t2 to t3 (electrode minus period Ten)
When the electrode positive polarity EP is switched to the electrode negative polarity EN at time t2, a predetermined electrode negative current that does not cause droplet transfer during a predetermined electrode negative period Ten as shown in FIG. Energize Ien. Further, as shown in FIG. 5B, the welding voltage Vw during this period becomes the electrode minus voltage Ven corresponding to the energization of the electrode minus current Ien. In addition, when the polarity is switched at the time t2, the arc of the electrode positive polarity once disappears. Therefore, in order to re-ignite the arc with the electrode minus polarity, as shown in FIG. It is necessary to apply the re-ignition voltage Vrs between the welding wire (−) and the workpiece (+) for only a short time.

(3) Period from time t3 to t4 (base period Tb)
When the electrode negative polarity EN is switched to the electrode positive polarity EP at time t3, a predetermined base current Ib that does not cause droplet transfer is applied during the base period Tb, as shown in FIG. . Further, as shown in FIG. 5B, the welding voltage Vw during this period is the base voltage Vb corresponding to the energization of the base current Ib. At the end of the base period Tb (time t4), the welding voltage Vw, that is, the average value of the peak voltage Vp and the base voltage Vb during the electrode positive polarity period is the predetermined voltage setting value Vs shown in FIG. It is automatically determined by being controlled to be equal to.

  Further, as described above, since the arc of the electrode minus polarity EN once disappears even at the time of polarity switching at the time t3, the arc is re-ignited with the electrode plus polarity EP as shown in FIG. Thus, it is necessary to apply the re-ignition voltage Vrs of about 300 [V] between the welding wire (+) and the work piece (−) only for a short time.

  In the AC arc welding method in which the welding current Iw and the welding voltage Vw described above are applied, the heat input to the work piece and the wire melting amount are controlled by controlling the EN ratio, which is the ratio of the electrode minus current and the electrode plus current. It can be controlled precisely. Here, the EN ratio is generally set as one of the following.

  The EN ratio is set as EN ratio = (Ien × Ten) / {(Ip × Tp + Ib × Tb) + (Ien × Ten)} as a ratio of the product of the welding current Iw and the energization period T. Alternatively, the EN ratio is set as EN ratio = Ten / (Tp + Tb + Ten) as the ratio of the electrode minus period Ten within one cycle. (For example, refer to Patent Document 1).

  Even if this EN ratio is changed, the supply amount of the welding wire per unit time is constant. Therefore, as shown in FIG. 12 (A), when the EN ratio is small, the penetration depth into the workpiece 7 increases, and the weld bead 15 becomes flat. Conversely, as shown in FIG. 4D, when the EN ratio is large, the penetration depth into the work piece 7 decreases, the surplus height increases, and the shape of the weld bead 15 is convex. Become a shape. FIG. 12 is a diagram showing the relationship between the EN ratio and the shape of the weld bead 15.

  Therefore, when performing fillet welding of a lap joint having a gap 18 between the upper plate 16 and the lower plate 17, as shown in FIG. 13A, if the EN ratio is reduced, the melt into the lower plate 17 is achieved. Although the depth increases, the surplus is flattened, and the weld bead 15 cannot be bridged between the upper plate 16 and the lower plate 17. Conversely, as shown in FIG. 5B, the weld bead 15 can be bridged between the upper plate 16 and the lower plate 17 by increasing the EN ratio. However, there is a problem that the welding to the lower plate 17 is insufficient, resulting in poor welding. FIG. 13 is a diagram illustrating the shape of the weld bead 15 when the EN ratio is changed when performing fillet welding of a lap joint having a gap 18 between the upper plate 16 and the lower plate 17.

[Prior Art 3]
Therefore, there has been proposed a laser irradiation AC arc welding method in which laser irradiation and consumable electrode gas shield AC arc welding are used in combination by combining the above-described conventional technology 1 and conventional technology 2. FIG. 14 is a view for explaining a laser irradiation AC arc welding method, in which FIG. 14 (A) is a view seen from a direction perpendicular to the weld joint, and FIG. 14 (B) is a view of the weld joint direction. It is the figure seen from. In this welding method, as shown in the figure, when performing fillet welding of a lap joint having a gap 18 between an upper plate 16 and a lower plate 17, laser light output from the laser torch 12 shown in FIG. The irradiation position 10 is a position 16b slightly above the lower end portion 16a of the upper plate 16.

  And the arc generated from the welding torch 5 is generated with fillet welding by generating the joint line 19 where the lower end portion 16a of the upper plate of the lap joint overlaps the surface of the lower plate 17 as a target position. Then, the EN ratio of AC arc welding is increased corresponding to the length of the gap 18, and the weld bead is bridged between the upper plate 16 and the lower plate 17.

  Thereby, since the irradiation position of the laser beam 10 is on the upper plate 16 side, the arc generated from the welding torch 5 is concentrated on the laser irradiation position, and the height of the weld bead can be increased. Further, it is possible to prevent the burn-through that occurs when the irradiation position of the laser beam 10 is set to the lower plate 17. Furthermore, since the lower plate 17 is also melted by the energy of the laser beam 10 irradiated on the upper plate 16, it is possible to compensate for the lack of penetration.

As a result, as shown in FIG. 15, a uniform weld bead 15 can be formed by bridging the upper plate 16 and the lower plate 17. Moreover, a sufficient penetration depth can be obtained, and the weld bead 15 having a high joint strength can be formed. FIG. 15 is a diagram illustrating a welding result obtained by the laser irradiation AC arc welding method of the prior art 3. However, it has the problems described below.
JP 2002-192363 A

  When fillet welding a lap joint having a gap 18 between the upper plate 16 and the lower plate 17 by the laser irradiation AC arc welding method of the prior art 3 described above, as shown in FIG. The tangent angle θ1 of the boundary portion 15a of the weld bead 15 is increased. As a result, the stress tends to concentrate on the boundary portion 15a, and there is a problem that the fatigue strength is reduced.

  As a method of reducing the concentration of this stress, there is a method of finishing the weld bead 15 smoothly with a grinder or the like. However, since an operator must hold and grind a cutting tool such as a grinder for a long time, work efficiency decreases. Furthermore, it is difficult for the operator to stably and uniformly grind, and the work piece may be damaged.

  In the fillet welding of a lap joint having a gap between an upper plate and a lower plate, the present invention provides a weld bead having a uniform and sufficient penetration depth and a large joint strength between the upper plate and the lower plate. It can be formed by bridging. Furthermore, it aims at providing the laser irradiation arc welding method which can improve fatigue strength.

While irradiating the fillet welded part of the lap joint with a gap between the upper plate and the lower plate with laser light,
In the laser irradiation arc welding method in which consumable electrode gas shield arc welding is performed by supplying AC power with an EN ratio that is a ratio of electrode minus current and electrode plus current between the welding wire and the lap joint,
Increasing the length of the gap increases the beam spot diameter of the laser light and increases the laser output corresponding to the beam spot diameter; and
The laser beam is irradiated to the lower plate side, and the laser beam is irradiated so that the outer shape of the beam spot substantially coincides with a joint line where the lower end portion of the upper plate overlaps the surface of the lower plate. This is a laser irradiation arc welding method.

  In the laser irradiation arc welding method of the present invention, when performing fillet welding of a lap joint having a gap between an upper plate and a lower plate, a uniform weld bead is formed by bridging the upper plate and the lower plate. be able to. Furthermore, a sufficient penetration depth can be obtained, a joint strength can be increased, and a weld bead with a small tangent angle at the boundary of the weld bead in the lower plate can be formed. Therefore, it is difficult for stress to concentrate on the boundary between the weld bead and the lower plate, and the fatigue strength can be improved.

[Embodiment 1]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the invention will be described based on examples with reference to the drawings.
FIG. 1 is a diagram for explaining a laser irradiation arc welding method according to Embodiment 1 of the present invention, and FIG. 1 (A) is a diagram viewed from a direction perpendicular to a welded joint. B) is a view as seen from the weld joint direction. In the figure, when a lap joint having a gap 18 between the upper plate 16 and the lower plate 17 is fillet welded, the beam on the surface of the lower plate 17 of the laser beam 10 increases as the length of the gap 18 increases. The outer shape of the spot 10a is such that the lower end portion 16a of the upper plate of the lap joint is substantially outside the joint line 19 that overlaps the surface of the lower plate 17 (X1 direction of X1-X2 shown in the figure). The lower plate 17 is irradiated with the laser beam 10 output from the laser torch 12 shown in FIG. The diameter of the beam spot 10a is increased in order to prevent the laser spot from being melted off. When the diameter of the beam spot 10a is increased, the energy density is lowered. Therefore, the laser output of the laser oscillator 9 shown in FIG. 8 is increased in correspondence with the diameter of the beam spot 10a within a range where no burn-out occurs. I am letting.

  Then, an arc is generated from the welding torch 5 with the joint wire 19 as a target position. Further, fillet welding is performed by increasing the EN ratio of the AC power supplied between the welding wire 4 and the lap joint as the length of the gap 18 increases. At this time, even if the EN ratio is increased, since the lower plate 17 is melted by the energy of the laser beam 10, the lack of penetration can be compensated.

  As a result, as shown in FIG. 4B to be described later, a uniform weld bead 15 can be formed by bridging the upper plate 16 and the lower plate 17. Furthermore, it is possible to form a weld bead 15 having a sufficient penetration depth, a high joint strength, and a small tangent angle θ1 of the boundary portion 15a of the weld bead 15 in the lower plate 17. Therefore, it is difficult for stress to concentrate on the boundary portion 15a, and fatigue strength can be improved.

  Examples will be described below. FIG. 2 is a view for explaining a state in which the lap joint of the embodiment of the laser irradiation arc welding method of the present invention is fixed with a jig, and FIG. 2 (A) is a plan view. (B) is a front view. In the figure, both the upper plate 16 and the lower plate 17 are cut to a width of 60 mm and a length of 300 mm, and the material is a high-tensile steel plate. The thickness of the lower plate 17 is 1.6 mm, and the upper plate 16 is 1.2 mm. The lower plate 17 is placed on the work table 20, and the upper plate holding member 21 is placed between the upper plate 16 and the lower plate 17 so that the gap between the upper plate 16 and the lower plate 17 is held at 0, 6 mm. Provided in between, the upper plate 16 and the lower plate 17 are overlapped by 10 mm, and the upper plate 16 is pressed by the pressing jig 22 and fixed on the work table 20.

  The welding conditions are set such that the laser output is 2 kW, the diameter of the beam spot 10 a on the surface of the lower plate 17 of the laser beam 10 is 2.0 mm, and the outer shape of the beam spot 10 a is almost equal to that of the joint line 19. The lower plate 17 is irradiated with the laser light 10 so as to be outside (X1 direction of X1-X2 shown in FIG. 1). The welding current for arc welding is set to 200 A, the welding voltage is set to 21 V, the EN ratio is set to 10%, the welding speed is set to 300 cm / min, and the distance in the welding direction between the laser irradiation position and the target position of the arc is set to 3.0 mm. The fillet welding was performed with the laser beam 10 in advance.

  And the macro cross section observation and fatigue test of the welding part vicinity were implemented. The fatigue test was a test piece shown in FIG. The single swing plane bending test is a test in which one of the test pieces is fixed and a constant pressure is continuously applied to the other to vibrate, and the number of vibrations until the joint breaks is measured. FIG. 3A is a plan view of a test piece used in the fatigue test, and FIG. 3B is a front view.

  First, the observation result of the macro cross section near the weld will be described. 4A is a macro sectional view showing a welding result by the laser irradiation arc welding method of the prior art 3, and FIG. 4B is a macro sectional view showing a welding result by the laser irradiation arc welding method of the present invention. It is. The welding conditions of the laser irradiation arc welding method of the prior art 3 are as follows. In FIG. 14, the laser output is 2 kW, the beam spot diameter is minimized, and the laser beam irradiation position 16b is only 0.5 mm from the lower end portion 16a of the upper plate. The upper position. Then, the welding current of arc welding is set to 200A, the welding voltage is set to 21V, the EN ratio is set to 10%, the welding speed is set to 300 cm / min, the welding target position is set as the joint line 19, and the laser irradiation position and the arc target position are set. Fillet welding was performed with the distance in the welding direction set to 3.0 mm and the laser beam 10 preceding.

  The welding result by the laser irradiation arc welding method of the present invention shown in FIG. 4B is compared with the welding result by the laser irradiation arc welding method of the prior art 3 shown in FIG. The weld bead 15 having a small tangent angle θ1 of the boundary portion 15a could be formed. As a result, it was difficult for stress to concentrate on the boundary 15a of the weld bead in the lower plate 17, and the fatigue strength could be improved.

  Next, the results of the fatigue test will be described. FIG. 5 is a view showing a fatigue test result of a lap joint by the laser irradiation arc welding method of the prior art 3 and the present invention. In the figure, for example, the pressure at which the number of vibrations is ruptured at 2 million times is less than 300 MPa in the prior art 3, whereas it is about 400 MPa in the present invention. Therefore, the present invention was able to improve the fatigue strength about 1.5 times that of the prior art 3.

[Embodiment 2]
FIG. 6 shows a welding apparatus for carrying out the laser irradiation arc welding method according to the second embodiment of the present invention. In the figure, the laser torch 12 is attached to the tip of the arm 31 of the laser manipulator 30, and the welding torch 5 is attached to the tip of the arm 33 of the welding manipulator 32. The AC arc welding power source 14 controls the rotation of the welding wire feeding roll of the welding wire feeder 2 so that the welding wire 4 is fed through the welding torch 5. Further, the AC arc welding power source 14 supplies an electric power between the power feed tip provided in the welding torch 5 and the workpiece 7 to generate an arc.

  Further, the laser beam 10 output from the laser oscillator 9 is transmitted to the condensing lens optical system of the laser torch 12 by the optical fiber 11, and is converged so that a focus is generated on the workpiece 7 by the condensing lens optical system. Irradiated. The position where the laser beam 10 is irradiated is a position having an appropriate distance from the arc generation part of the work piece 7.

  A command signal S1 is input from the teach pendant 34 to the robot control device 35, and an operation control signal S2 from the robot control device 35 is input to the welding manipulator 32, so that six axes including the first to sixth axes are displayed. The welding target position of the welding torch 5 is controlled by rotating. Further, an operation control signal S3 from the robot control device 35 is input to the laser manipulator 30, and the six axes including the first to sixth axes are rotated to control the laser irradiation position of the laser torch 12.

  The laser sensor 36 detects the length of the gap and the joint line, and outputs a detection signal S4 to the robot controller 35. The robot controller 35 inputs an operation control signal S3 for controlling the target position of the laser beam 10 to the laser manipulator 30 in accordance with the length of the gap. Further, a beam spot diameter setting signal S5 for setting the beam spot diameter on the workpiece 7 corresponding to the gap length is output to the beam spot diameter adjusting mechanism 37. The beam spot diameter adjusting mechanism 37 adjusts the beam spot diameter by adjusting the condensing lens optical system in accordance with the length of the gap. Further, the robot controller 35 outputs an output control signal S6 that causes the laser oscillator 9 to increase the laser output in accordance with the beam spot diameter.

  The position where the laser sensor 36 is provided may be provided between the laser torch 12 and the welding torch 5 with respect to the welding direction, as shown in FIG. 7 (A), or as shown in FIG. 7 (B). You may provide in front of the laser torch 12 with respect to a direction. FIG. 7 is a diagram showing a position where the laser sensor 36 is provided.

  By the welding apparatus described above, the irradiation position of the laser beam 10 is adjusted corresponding to the gap length of the lap joint, the beam spot diameter is increased, and the laser output is increased corresponding to the beam spot diameter to fillet weld It is possible to carry out the laser irradiation arc welding method of the present invention.

It is a figure for demonstrating the laser irradiation arc welding method of Embodiment 1 of this invention. It is a figure for demonstrating the state which has fixed the lap joint of the Example of the laser irradiation arc welding method of this invention with the jig | tool. It is a figure which shows the test piece used for a fatigue test. It is macro sectional drawing which shows the welding result by the laser irradiation arc welding method of the prior art 3 and this invention. It is a figure which shows the fatigue test result of the lap joint by the laser irradiation arc welding method of the prior art 3 and this invention. It is a welding apparatus for enforcing the laser irradiation arc welding method of Embodiment 2 of this invention. It is a figure which shows the position which provides the laser sensor. It is a figure which shows the welding apparatus for enforcing the general laser irradiation DC arc welding method. It is a figure which shows a general laser irradiation arc welding head. It is a figure which shows the welding apparatus for enforcing the alternating current arc welding method of the prior art 2. FIG. It is a figure which shows the output waveform of the alternating current arc welding power supply 14 of the alternating current arc welding method of the prior art 2. FIG. It is a figure which shows the relationship between the EN ratio of the alternating current arc welding method of the prior art 2, and the shape of the welding bead 15. FIG. It is a figure which shows the shape of the weld bead 15 when changing an EN ratio, when performing fillet welding of the lap joint which has the gap 18 between the upper board 16 and the lower board 17. FIG. It is a figure for demonstrating the laser irradiation alternating current arc welding method. It is a figure which shows the welding result by the laser irradiation alternating current arc welding method of the prior art 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply apparatus for DC arc welding 2 Welding wire feeder 3 Welding wire feeding roll 4 Welding wire 5 Welding torch 6 Welding torch body 7 Work piece 8 Arc 9 Laser oscillator 10 Laser beam 10a Beam spot 11 Optical fiber 12 Laser torch 13 Condenser lens optical system 14 AC arc welding power source 15 Weld bead 15a Boundary portion 16 of weld bead in lower plate Upper plate 16a Lower end portion 16b Position 16b Irradiation position 17 Lower plate 18 Gap 19 Joint wire 20 Work table 21 Upper plate holding member 22 Jig 30 Laser manipulator 31 Arm 32 Welding manipulator 33 Arm 34 Teach pendant 35 Robot controller 36 Laser sensor 37 Beam spot diameter adjusting mechanism EN Electrode minus polarity EP Electrode plus polarity Ib Base current Ien Electrode minus current Ip Peak Flow Iw Welding current S1 Command signal S2 Operation control signal S3 Operation control signal S4 Detection signal S5 Beam spot diameter setting signal S6 Output control signal T Energization period t1 Time t2 Time t3 Time t4 Time Tb Base period Ten Electrode minus period Tp Peak period Vb Base voltage Ven Electrode negative voltage Vp Peak voltage Vrs Re-ignition voltage Vs Voltage setting value Vw Welding voltage θ1 Tangent angle

Claims (1)

While irradiating the fillet welded part of the lap joint with a gap between the upper plate and the lower plate with laser light,
In the laser irradiation arc welding method in which consumable electrode gas shield arc welding is performed by supplying AC power with an EN ratio that is a ratio of electrode minus current and electrode plus current between the welding wire and the lap joint,
Increasing the length of the gap increases the beam spot diameter of the laser light and increases the laser output corresponding to the beam spot diameter; and
The laser beam is irradiated to the lower plate side, and the laser beam is irradiated so that the outer shape of the beam spot substantially coincides with a joint line where the lower end portion of the upper plate overlaps the surface of the lower plate. Laser irradiation arc welding method.

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