JP2011218395A - Hybrid plasma welding method, hybrid plasma torch, and hybrid welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high-speed welding capable of obtaining a weld bead having a smooth surface even by application of a laser beam of relatively low power.SOLUTION: An object to be welded is subjected to the plasma arc welding by the plasma arc between each of a plurality of plasma discharge electrodes 8a, 8b which are inclined on the torch fore end side so as to be closer to the torch center line CL and are arranged on the upstream and downstream sides in the welding direction y with respect to the torch center line and the object 12 to be welded. The laser beam 13 to be converged toward the torch fore end around the center line CL is applied to a molten pool by the plasma arc of the plasma discharge electrode 8b on the upstream side in the welding direction to deepen penetration in the backside direction. A raise in the surface side direction of a weld part by applying the laser beam is smoothed by the plasma arc welding using the plasma discharge electrode 8a on the downstream side.

Description

  The present invention relates to a hybrid plasma welding method that is a combination of plasma welding and laser welding, a hybrid plasma welding torch and a hybrid plasma welding apparatus used therefor.

  In thin plate butt welding using a laser and having a thickness of 2.0 mm or less, as shown in FIG. 8, a force in the direction of separating the butt is generated on the welding target material 12 in front of the welding. If the butt gap is 0.2 to 0.3 mm or more, poor fusion occurs in the butt weld. Therefore, it is necessary to strongly suppress the welding target material 12 with a hydraulic clamp, which increases equipment and work amount. The butt end portion is also temporarily attached prior to laser welding, but in this case, the tact time becomes long.

  As shown in FIG. 9 (a), in the aspect in which the welding wire is fed to the laser irradiation point of laser welding, the butt gap is filled with the droplet of the wire, but the wire is thicker than the laser beam diameter. Since the wire is not melted by a slight wire shift, poor fusion occurs. Further, as shown in FIG. 9B, when the gap between the upper and lower welding target materials is large in the lap welding, the welding proceeds as shown in FIG. 9C, but much to melt the wire. Since the laser energy is consumed and the penetration becomes shallow and the molten pool sinks in the upper and lower gaps, as shown in FIG. 9 (d), it becomes a concave bead, the throat thickness becomes thin, and the strength decreases. If the wire supply amount is increased in order to prevent this, the laser penetrating force decreases, resulting in poor welding. Conversely, when the vertical gap becomes zero, a convex bead as shown in FIG.

  Patent Document 1 describes hybrid welding in which a butt portion is melted by a welding torch and a laser is irradiated to a molten pool, and formation of an air curtain that prevents contamination of a laser beam path. However, in hybrid welding, the butt surface is welded with a welding torch and the center of the molten pool is irradiated with a laser as shown in FIG. 7 (b). As shown, it projects at the center and undercuts at the edge. When the welding speed is lowered or the laser power is increased, a smooth weld bead with a low protrusion at the center and no undercut can be obtained, but the welding work efficiency is lowered. Alternatively, an expensive high power laser device must be used.

Special table 2004-512965 gazette

  An object of the present invention is to enable high-speed welding in which a weld bead with a smooth surface can be obtained even by relatively low power laser projection.

  (1) A plurality of plasma discharge electrodes (8a, 8b) which are inclined to approach the torch center axis (CL) on the torch tip side and are arranged upstream and downstream in the welding direction (y) with respect to the torch center axis. Laser beam (13) that converges toward the tip of the torch with the plasma arc welding of the material to be welded (12) by plasma arc between each and the material to be welded (12), and centering on the torch center axis (CL) In the welding direction (y) to the molten pool by the plasma arc of the upstream plasma discharge electrode (8b) to deepen the penetration in the back direction, and the rise in the front direction of the weld by the laser beam projection Which is smoothed by plasma arc welding with a plasma discharge electrode (8a) on the downstream side.

  For ease of understanding, reference numerals of corresponding elements in the examples shown in the drawings and described later are added in parentheses for reference. The same applies to the following.

  For example, as shown in FIG. 6, a plasma arc is formed between each of the pair of plasma discharge electrodes 8a and 8b and the welding target material 12, a plasma beam 13 is projected between the electrodes 8a and 8b, and the welding direction is set. If the y direction shown in the drawing is taken, that is, if the electrode 8b is the leading electrode and the electrode 8a is the trailing electrode, the plasma arc of the leading electrode (only one) is conventional, but in the present invention, the leading electrode 8b and the trailing electrode are used. Since the plasma arc of the electrode 8a heats the welding object material 12, the amount of heat is large and high speed welding is possible. In the high-speed welding, a force that closely contacts the groove joining surface in the direction indicated by an arrow on FIG. 6 acts on the welding target material 12 by plasma arc welding using the leading electrode 8b. This is because when the arc heat source (plasma arc) by the leading electrode 8b moves faster (precedingly) than the heat conduction speed of the welding target material 12, the elongation of the steel material behind the arc heat source becomes larger than the front elongation. It is. This narrows the gap between the butted surfaces.

  Since the plasma arc of the leading electrode 8b melts the surface of the material 12 to be welded, a molten pool is formed that bridges the butt gap as shown in FIG. 7 (a) as shown in FIG. 7 (b). A laser beam vertically penetrates the molten pool to efficiently input heat. Since this heat input is high density but the region is narrow and pinpointed, the weld bead thus formed is prone to undercut as the laser incident portion protrudes as shown in FIG. Although it is possible to make the laser beam stronger and broaden the beam diameter, it is possible to flatten the protrusion and eliminate the undercut, but such a laser device is quite expensive.

  However, according to the present invention, since the plasma arc of the succeeding electrode 8a further enters the laser-projected weld, the bead surface is smoothed and no undercut occurs. That is, the weld bead is smoothed as shown in FIG. As described above, according to the present invention, it is possible to perform high-speed welding in which a weld bead having a smooth surface can be obtained even by laser projection with relatively low power.

One Example of the hybrid plasma welding apparatus of this invention is shown, The laser head 1 and the plasma torch 3 show a longitudinal cross-section. It is the cross-sectional view of the plasma torch 3 shown in FIG. FIG. 3 is a longitudinal sectional view of the plasma torch 3 shown in FIG. 1 taken along the line III-III shown in FIG. FIG. 4 is a longitudinal sectional view of the plasma torch 3 shown in FIG. 1 taken along the line IV-IV shown in FIG. 2. It is an enlarged view of the lower end part of the plasma torch 3 shown in FIG. It is a top view of the welding target material 12 at the time of hybrid plasma welding using the plasma torch 3 shown in FIG. It is a cross-sectional enlarged view of the welding object material in each position of the welding direction at the time of hybrid plasma welding shown in FIG. It is a top view which shows expansion of the butt gap of the welding object material at the time of the butt welding by the conventional laser projection. (A) is a plan view of a material to be welded at the time of conventional superposition laser welding for feeding a welding wire, (b) is a side view, (c) a longitudinal sectional view of a weld bead, (d) and (e) ) Is a cross-sectional view of a weld bead.

  (2) Between the welding object material (12) and each plasma discharge electrode (8a, 8b), a current that is positive on the welding object material side and negative on the electrode side is energized, and the plurality of plasma discharge electrodes (8a, 8b ) And a welding target material, a plasma arc is generated. The hybrid plasma welding method according to (1) above.

  (3) The hybrid plasma welding method according to the above (1) or (2), wherein the welding wire (18) is fed directly under the tip of the plasma discharge electrode (8b) upstream in the welding direction (y).

  (4) Heating the welding wire (18) by passing a current between the welding target material (12) and the welding wire (18) with a positive current on the welding target material side and a negative welding wire side. ) Hybrid plasma welding method.

(5) a plurality of plasma discharge electrodes (8a, 8b) that are inclined so as to approach the torch center axis (CL) on the torch tip side and are arranged upstream and downstream in the welding direction with respect to the torch center axis;
A hybrid plasma torch (3) comprising: a laser transmission hole (24) penetrating from the rear end of the torch to the tip with the torch center axis (CL) as an axis.

  (6) The hybrid plasma torch (3) according to (5), wherein the plurality of plasma discharge electrodes (8a, 8b) are symmetrical with respect to the torch center axis (CL).

  (7) The hybrid plasma torch (3) according to (5) or (6) above; and a laser head (1) that projects a laser beam that converges toward the tip of the torch at the laser transmission hole (24). A hybrid plasma welding apparatus provided.

  (8) A plasma welding power source (22a, 22b) for passing a current that is positive on the welding target material side and negative on the electrode side between the welding target material (12) and each plasma discharge electrode (8a, 8b). The hybrid plasma welding apparatus according to (6).

(9) The above (7) or (8), further comprising a wire guide (21) for guiding the welding wire (18) immediately below the tip of the plasma discharge electrode (8b) upstream in the welding direction (y). Hybrid plasma welding equipment;
(10) The above further includes a hot wire power source (23) between the material to be welded (12) and the welding wire (18) for supplying a current that is positive on the material to be welded side and negative on the side of the welding wire. The hybrid plasma welding apparatus according to 9).

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows an outline of a hybrid plasma welding apparatus according to one embodiment of the present invention. The hybrid plasma torch 3 has a laser transmission hole 24 centered on the central axis, and extends from the rear end of the torch (laser head 1 side) to the insert tip 7 at the front end of the torch. The laser transmitting hole 24 is an insulating space between the electrode bases 4a and 4b at the rear end of the torch, but has a stepped cylindrical shape in the insulating base 5 and a truncated cone shape in the insulating base 6 and the insert tip. The plasma discharge electrodes 8a and 8b are arranged symmetrically with respect to the central axis CL of the torch 3, and the electrodes 8a and 8b are arranged so as to approach the central axis CL from the rear end side of the torch toward the insert tip 7. It is inclined with respect to. Plasma gas fed from the plasma gas supply ports 11a and 11b flows into the space through which the electrodes 8a and 8b pass, and is ejected from the nozzle at the tip of the insert tip 7 toward the welding target material 12. The shield gas is supplied to the shield gas passage 14 shown in FIGS. 2 and 3, flows into the shield cap 10, and is ejected from the lower opening of the shield cap 10 toward the welding target material 12. The laser shield gas is supplied to the laser shield gas channel 15 shown in FIGS. 2 and 3, passes through the channel of the insulating table 5, exits the laser transmission hole 24, and flows out from the laser projection port of the insert chip 7. The flow of the laser shield gas to the rear end side of the torch is blocked by the protective glass 9. The laser beam 13 passes through the protective glass 9. The cooling water flows into each water supply channel 16 shown in FIGS. 2 and 4 and reaches the insert tip 7 through the electrode bases 4a and 4b and the insulating bases 5 and 6, where it is folded back to another flow path and becomes the insulating bases 5 and 6. And it flows out from each drainage channel 17 through electrode stand 4a, 4b.

  Please refer to FIG. 1 again. The hybrid plasma torch 3 is connected to the laser head by the connecting member 2, and the laser head converges and projects the laser beam 13 to the laser transmission hole 24, and the laser beam 13 converges on the welding target material 12. The plasma power sources 22a and 22b pass through the electrodes 4a and 4b with a current that is positive on the welding object 12 side and negative on the electrodes 4a and 4b side. There is a pilot power source for starting a plasma arc by these power sources 22a and 22b, but these are not shown. In the embodiment shown in FIG. 1, in order to increase the amount of molten metal in the preceding welding by the preceding electrode 8b, the welding wire 21 is fed through the wire guide 21 directly below the preceding electrode 8b, and the welding heat input is increased to perform welding. In order to increase the speed, the hot wire power supply 23 is supplied to the welding wire 18 with a positive current on the welding object 12 side and a negative current on the welding wire 18 side.

  FIG. 5 shows an enlarged view of the tip of the torch during lap welding of the hybrid plasma welding apparatus shown in FIG. When a plasma arc is generated between each electrode 8a, 8b and the welding target material 12 and the electrode side is negative and the welding target material side is positive, a plasma arc current flows between each electrode and the welding target material 5 and 1 pool 2 Arc welding is realized. Each arc current flowing between the electrodes 8a and 8b in the insert tip 7 and the welding target material 12 is expressed by Fleming's left-hand rule between the combined magnetic fluxes induced by the respective arc currents. A pinch force acts, the plasma arc of each electrode is narrowed in the torch alignment direction y, the heat convergence effect (energy density) on the material to be welded 5 is high, and the plasma does not fluctuate and the stability of the plasma is high. .

  Since the plasma arc of the leading electrode 8b, the welding wire 18 and the trailing electrode 8a heats the welding object material 12, the amount of heat is large and high-speed welding is possible. Since the plasma arc of the leading electrode 8b melts the surface of the welding wire 18 and the welding target material 12, a large amount of molten metal penetrates the laser beam 13 vertically as shown in FIG. Since this heat input is high density, but the region is narrow and pinpointed, the weld bead thus produced tends to cause an undercut due to the projection of the laser incident portion. However, since the plasma arc of the succeeding electrode 8a further enters the laser-projected weld, the bead surface is smoothed and undercut does not occur. That is, the weld bead has a smooth surface. As described above, according to the present embodiment, high-speed welding is possible in which a weld bead having a smooth surface can be obtained even by relatively low power laser projection.

1: Laser irradiation head 2: Connecting member 3: Hybrid plasma torch 4a, 4b: Electrode base 5, 6: Insulating base 7: Insert tip 8a, 8b: Electrode 9: Protective glass 10: Shield cap 11a, 11b: Plasma gas supply Port 12: Material to be welded 13: Laser 14: Shield gas channel 15: Laser shield gas channel 16: Water supply channel 17: Drainage channel 18: Welding wire 19: Molten metal by preceding plasma arc 20: Melting by subsequent plasma arc Metal 21: Wire guides 22a, 22b: Plasma power source 23: Hot wire power source 24: Laser transmission hole CL: Center axis

Claims (10)

  A target to be welded by a plasma arc between each of a plurality of plasma discharge electrodes disposed on the upstream side and the downstream side in the welding direction with respect to the central axis of the torch and inclined to approach the central axis of the torch at the tip of the torch. In addition to plasma arc welding of the material, a laser beam that converges toward the tip of the torch centering on the center axis of the torch is projected onto the molten pool by the plasma arc of the plasma discharge electrode on the upstream side in the welding direction to melt in the reverse direction. A hybrid plasma welding method for deepening the depth and smoothing the bulge in the front direction of the welded portion by the laser beam projection by plasma arc welding with a plasma discharge electrode on the downstream side.   A current that is positive on the welding target material side and negative on the electrode side is passed between the welding target material and each plasma discharge electrode, and a plasma arc is generated between each of the plurality of plasma discharge electrodes and the welding target material. The hybrid plasma welding method according to claim 1.   The hybrid plasma welding method according to claim 1 or 2, wherein a welding wire is fed immediately below the tip of the plasma discharge electrode that is upstream in the welding direction.   4. The hybrid plasma welding method according to claim 3, wherein the welding wire is heated by passing a current that is positive on the welding target material side and negative on the welding wire side between the welding target material and the welding wire. A plurality of plasma discharge electrodes disposed on the upstream side and the downstream side in the welding direction with respect to the torch center axis, inclined to approach the torch center axis on the torch tip side; and
A hybrid plasma torch comprising: a laser transmission hole penetrating from the rear end of the torch to the front end with the torch central axis as an axis.   The hybrid plasma torch according to claim 5, wherein the plurality of plasma discharge electrodes are symmetrical with respect to the central axis of the torch.   A hybrid plasma welding apparatus comprising: the hybrid plasma torch according to claim 5; and a laser head that projects a laser beam that converges toward the tip of the torch to the laser transmission hole.   The hybrid plasma welding apparatus according to claim 6, further comprising: a plasma welding power source for passing a current that is positive on the welding target material side and negative on the electrode side between the welding target material and each plasma discharge electrode.   Furthermore, the hybrid plasma welding apparatus of Claim 7 or 8 provided with the wire guide which guides a welding wire just under the front-end | tip of the plasma discharge electrode upstream in a welding direction.   The hybrid plasma welding apparatus according to claim 9, further comprising: a hot-wire power source that conducts a positive current between the welding target material and the welding wire, the welding target material side being positive and the welding wire side being negative.

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