Abstract: A plasma ejection unit (21) of an arc welding device includes a plasma torch (26), a copper plate (27), a container (28), and a gas supplying unit (29). Plasma gas inside the container (28) is pressurized by argon gas supplied from the gas supplying unit (29), and ejected from first to eighth ejection ports. The plasma gas ejected from the first to eighth ejection ports is concentrated in a concentration area (CA) between vehicle body plates (16-17) to form through holes (40) in the vehicle body plates (16-17), and is separated. The air pressures, in eight areas, of the plasma gas reaching a vehicle body plate (18) are approximately one-eighth of the air pressure of the plasma gas in the concentration area (CA). Accordingly, while the through holes (40) are formed in the vehicle body plates (16-17), no through hole is formed in the vehicle body plate (18).

Abstract: A penetration welding method includes a plasma welding step for forming a through hole in a work, which is a laminated steel plate, from a front surface to rear surface thereof without forming a hole in a component at the rear, by generating a plasma arc column from a plasma torch to the work. After the plasma arc column is generated, the plasma arc column is extinguished when an arc voltage or the length of the arc estimated from the arc voltage exceeds an end-determining threshold which is determined according to the thickness of the work. Further, plasma gas is discharged from the plasma torch at a flow rate at which the width of the plasma arc column is maintained approximately constant from the plasma torch side to the work side so that the arc voltage is increased at an approximately constant rate before and after penetration.

Abstract: A penetration welding method includes a plasma welding step for forming a through hole in a work, which is a laminated steel plate, from a front surface to rear surface thereof without forming a hole in a component at the rear, by generating a plasma arc column from a plasma torch to the work. After the plasma arc column is generated, the plasma arc column is extinguished when an arc voltage or the length of the arc estimated from the arc voltage exceeds an end-determining threshold which is determined according to the thickness of the work. Further, plasma gas is discharged from the plasma torch at a flow rate at which the width of the plasma arc column is maintained approximately constant from the plasma torch side to the work side so that the arc voltage is increased at an approximately constant rate before and after penetration.

Abstract: A plasma ejection unit (21) of an arc welding device includes a plasma torch (26), a copper plate (27), a container (28), and a gas supplying unit (29). Plasma gas inside the container (28) is pressurized by argon gas supplied from the gas supplying unit (29), and ejected from first to eighth ejection ports. The plasma gas ejected from the first to eighth ejection ports is concentrated in a concentration area (CA) between vehicle body plates (16-17) to form through holes (40) in the vehicle body plates (16-17), and is separated. The air pressures, in eight areas, of the plasma gas reaching a vehicle body plate (18) are approximately one-eighth of the air pressure of the plasma gas in the concentration area (CA). Accordingly, while the through holes (40) are formed in the vehicle body plates (16-17), no through hole is formed in the vehicle body plate (18).

Abstract: Provided are a plasma-MIG welding method and a welding torch that are capable of reducing spatter amount without relying on control of a MIG welding power supply. The plasma-MIG welding method employs a plasma-MIG welding device configured from: a plasma torch section that includes a plasma nozzle and a plasma electrode; and an MIG torch that includes an MIG tip and a welding wire. The plasma torch section and the MIG torch are arranged so as to face in different directions at a predetermined distance from each other. The plasma-MIG welding method is characterized in that a plasma arc is made to locally overlap with a tip end portion of the welding wire, and in a state in which melting of the welding wire is promoted, MIG welding is carried out without short-circuiting between a workpiece and a tip end of the welding wire which is a consumable electrode.

Abstract: A plasma welding torch that can be reduced in size more than in conventional cases. When an inert gas G such as argon gas is supplied to an outer circumferential space around a non-consumable electrode 13, a portion of the inert gas G is used as plasma gas GP that forms a plasma arc PA between the non-consumable electrode 13 and a base material 2 via a plasma orifice 51. A plasma welding torch 1 moves, maintaining this state, in the direction of the arrow shown in FIG. 4. Meanwhile, a portion of the inert gas G supplied to a gas flowing part 21 is not used as the plasma gas GP but is used as shielding gas GS and is ejected onto the base material 2 ahead in the welding direction via a shielding orifice 52. The welding on the base material 2 is performed in a state where the plasma arc PA and the base material 2 are shielded from the air by this shielding gas.

Abstract: A laser-arc hybrid welding head performs laser light irradiation and arc discharge of a base material to weld the base material by combined use of laser welding and arc welding. The welding head includes an optical fiber for transmitting laser light used in laser welding and an arc electrode for generating an arc between the arc electrode and the base material. The optical fiber is disposed such that an optical axis thereof crosses an axis of the arc electrode at a predetermined angle.

Abstract: A plasma welding torch that can be reduced in size more than in conventional cases. When an inert gas G such as argon gas is supplied to an outer circumferential space around a non-consumable electrode 13, a portion of the inert gas G is used as plasma gas GP that forms a plasma arc PA between the non-consumable electrode 13 and a base material 2 via a plasma orifice 51. A plasma welding torch 1 moves, maintaining this state, in the direction of the arrow shown in FIG. 4. Meanwhile, a portion of the inert gas G supplied to a gas flowing part 21 is not used as the plasma gas GP but is used as shielding gas GS and is ejected onto the base material 2 ahead in the welding direction via a shielding orifice 52. The welding on the base material 2 is performed in a state where the plasma arc PA and the base material 2 are shielded from the air by this shielding gas.

Abstract: A laser-arc hybrid welding head for performing laser light irradiation and arc discharge of a base material to weld the base material by combined use of laser welding and arc welding, comprising: an optical fiber for transmitting laser light used in laser welding; and an arc electrode for generating an arc between the arc electrode and the base material, wherein the optical fiber is disposed such that an optical axis thereof crosses an axis of the arc electrode at a predetermined angle.