Abstract: The present invention pertains to a brazing method and a brazing apparatus. This brazing method comprises: a brazing material supply step for supplying a brazing material to a to-be-welded part; and a laser irradiation step for irradiating the brazing material having been supplied to the to-be-welded part with a laser beam while moving the laser beam along a brazing direction to form a welding bead. In the laser irradiation step, a gas is injected toward an area to be injected with gas, which is an area encompassing the welding bead located rearward of a laser-irradiated portion of the brazing material in the brazing direction, from above said area or from a front side of said area in the brazing direction.

Abstract: The vehicle roof structure includes: a closely facing section that abuts or is adjacent to a side outer panel; a negative curved-surface section that is positioned more inwards in the vehicle width direction than the closely facing section of the roof panel, and has a recessed face that is indented downwards; and a mounting surface that is formed in the side outer panel at an inner side in the vehicle width direction to downwards of the vehicle towards, and at which the closely facing section abuts or is adjacent, in which an edge, on a side of the roof panel, of the brazing material that has solidified to join the roof panel and the side outer panel is positioned on the negative curved-surface section.

Abstract: The vehicle roof structure includes: a closely facing section that abuts or is adjacent to a side outer panel; a negative curved-surface section that is positioned more inwards in the vehicle width direction than the closely facing section of the roof panel, and has a recessed face that is indented downwards; and a mounting surface that is formed in the side outer panel at an inner side in the vehicle width direction to downwards of the vehicle towards, and at which the closely facing section abuts or is adjacent, in which an edge, on a side of the roof panel, of the brazing material that has solidified to join the roof panel and the side outer panel is positioned on the negative curved-surface section.

Abstract: A magnetic field is generated in a workpiece in a direction orthogonal to the joining direction, and as a result of the Lorentz force resulting from the magnetic field and the current between the plasma torch and the workpiece, the front tip side of the arc is bent forward in the direction of advancement of the plasma torch and welding is performed. The magnetic field strength of the welded part is adjusted by changing the relative positions of the plasma torch and a butting portion of the workpiece.

Abstract: A plasma torch 1 used in plasma-arc welding is provided with a rod-shaped electrode 10, a first cylindrical nozzle 11 which is provided to surround the electrode 10 and which injects a plasma gas and a second cylindrical nozzle 12 which is provided to surround the first nozzle 11 and which injects a shielding gas. A second injection opening 121 of the second nozzle 12 directs in a substantially parallel direction with respect to an axial direction of the electrode 10 or in a direction being away from the electrode 10, and a plurality of groove portions inclining with respect to the axial direction of the electrode 10 are formed in an outer circumferential surface of the first nozzle 11 or an inner circumferential surface of the second nozzle 12.

Abstract: A magnetic field is generated in a workpiece in a direction orthogonal to the joining direction, and as a result of the Lorentz force resulting from the magnetic field and the current between the plasma torch and the workpiece, the front tip side of the arc is bent forward in the direction of advancement of the plasma torch and welding is performed. The magnetic field strength of the welded part is adjusted by changing the relative positions of the plasma torch and a butting portion of the workpiece.

Abstract: There is provided a nut having a thread portion having a female thread, a metallic plate portion having a base segment, and a hardness gradient portion provided between the thread portion and the metallic plate portion. The thread portion, metallic plate portion and the hardness gradient portion are monolithic each other, a metallographic structure of the metallic plate portion differs from a metallographic structure of the thread portion and a hardness of the hardness gradient portion is lower than a hardness of the thread portion and lowers from the thread portion toward the metallic plate portion.

Abstract: A two-electrode arc welding device and two-electrode arc welding method are provided for performing welding with improved penetration performance using two non-consumable electrodes. In a two-electrode arc welding device, a power-supply unit outputs a straight-polarity voltage and a reverse-polarity voltage, which has a different electrical potential than the straight-polarity voltage. The straight-polarity voltage output from the power-supply unit is applied to a non-consumable electrode of a straight-polarity arc torch, whereby an arc is formed. The reverse-polarity voltage output from the power-supply unit is applied to a non-consumable electrode of a straight-polarity arc torch, whereby an arc is formed. An arc spacing distance, which is a distance between the ends of both the straight-polarity arc torch and the reverse-polarity arc torch, is set to be at least a minimum distance at which an arc will not occur therebetween (arc spacing critical distance).

Abstract: A plasma torch 1 used in plasma-arc welding is provided with a rod-shaped electrode 10, a first cylindrical nozzle 11 which is provided to surround the electrode 10 and which injects a plasma gas and a second cylindrical nozzle 12 which is provided to surround the first nozzle 11 and which injects a shielding gas. A second injection opening 121 of the second nozzle 12 directs in a substantially parallel direction with respect to an axial direction of the electrode 10 or in a direction being away from the electrode 10, and a plurality of groove portions inclining with respect to the axial direction of the electrode 10 are formed in an outer circumferential surface of the first nozzle 11 or an inner circumferential surface of the second nozzle 12.

Abstract: A two-electrode arc welding device and two-electrode arc welding method are provided for performing welding with improved penetration performance using two non-consumable electrodes. In a two-electrode arc welding device 1, a power-supply unit 11 outputs a straight-polarity voltage and a reverse-polarity voltage, which has a different electrical potential than the straight-polarity voltage. The straight-polarity voltage output from the power-supply unit 11 is applied to a non-consumable electrode 41 of a straight-polarity arc torch 14, whereby an arc is formed. The reverse-polarity voltage output from the power-supply unit 11 is applied to a non-consumable electrode 41 of a straight-polarity arc torch 15, whereby an arc is formed. An arc spacing distance L1, which is a distance between the ends of both the straight-polarity arc torch 14 and the reverse-polarity arc torch 15, is set to be at least a minimum distance at which an arc will not occur therebetween (arc spacing critical distance).

Abstract: There is provided a nut having a thread portion having a female thread, a metallic plate portion having a base segment, and a hardness gradient portion provided between the thread portion and the metallic plate portion. The thread portion, metallic plate portion and the hardness gradient portion are monolithic each other, a metallographic structure of the metallic plate portion differs from a metallographic structure of the thread portion and a hardness of the hardness gradient portion is lower than a hardness of the thread portion and lowers from the thread portion toward the metallic plate portion.

Abstract: A threading method for threading a work 18 includes a supporting portion moving-up step for moving a supporting portion 17 upward by a predetermined distance by using an elevational mechanism 15 without rotating a tap 20 inserted into the work 18. Thus, the bent state of the robot arm 11 can be eliminated by moving the supporting portion 17 upward. In this case, since the supporting portion 17 is moved upward artificially, the supporting portion 17 can be moved up in a short time. That is, the bent state of the robot arm 11 can be eliminated in a short time and so the processing efficiency of the threading step can be improved.

Abstract: A thread forming device 10a is provided with a thread forming tool 32 for forming a thread portion 14 at a frame 12, a first motor 38 for controlling to rotate the thread forming tool 32, and a second motor 40 for controlling to extract and retract the thread forming tool 32. Further, the thread forming tool 32 is provided with a pilot hole forming portion 86 provided with a spiral groove 80b at a front end portion 80 in a taper shape, and a thread forming portion 84 constituted continuously to the pilot hole forming portion 86 and provided with a spiral groove 84b.

Abstract: A thread forming device 10a is provided with a thread forming tool 32 for forming a thread portion 14 at a frame 12, a first motor 38 for controlling to rotate the thread forming tool 32, and a second motor 40 for controlling to extract and retract the thread forming tool 32. Further, the thread forming tool 32 is provided with a pilot hole forming portion 86 provided with a spiral groove 80b at a front end portion 80 in a taper shape, and a thread forming portion 84 constituted continuously to the pilot hole forming portion 86 and provided with a spiral groove 84b.