A beam vibrating mechanism vibrates a laser beam in a parallel direction with a cutting advancing direction of a sheet metal. An amplitude amount of the laser beam is Qx, a radius of a first circular region having an area occupying 86% beam energy at a center side of total beam energy in a sectional area of the laser beam on a top surface of the sheet metal is rtop, and a radius of a second circular region having an area occupying 86% beam energy at a center side of total beam energy in a sectional area of the laser beam in a bottom surface of the sheet metal is rbottom. A calculation value Va is expressed by the expression: Va=(Qx+rtop+√{square root over (2)}×rbottom). When a standard deviation of the calculation value Va at a time of cutting sheet metals of a plurality of plate thicknesses is Vasd, a nozzle having a diameter of an opening between a minimum value obtained by 2Va−Vasd, and a maximum value obtained by 2.5 Va+Vasd is used as a nozzle attached to a machining head.

Art for spot welding able to suppress penetration of hydrogen, one of the factors behind delayed fracture, at the time of spot welding, that is, a spot welding method in which at one or both of the surfaces of the steel sheets becoming the facing surfaces of the overlaid steel sheets, a location where the steel sheets contact each other to form a contact part at the time of initial squeezing of the spot welding is worked in advance to form a plurality of lines running through the contact part and connected to the outside of the contact part and the spot welding is performed at the location of the contact part and also a steel sheet in which the plurality of lines are formed in advance at the location becoming a contact part when steel sheets contact each other at the time of initial squeezing in the spot welding.

A machining head emits a laser beam for cutting sheet metal of stainless steel. A moving mechanism moves the machining head relatively to a surface of the sheet metal. A beam vibrating mechanism vibrates a laser beam in a parallel direction with a cutting advancing direction of the sheet metal. In a machining condition database, a single specific vibration frequency at which cutting of the sheet metal is possible is set to a maximum moving velocity at which cutting of the sheet metal is possible, and a plurality of vibration frequencies from a maximum frequency to a minimum frequency at which cutting of the sheet metal is possible are set to a moving velocity more than or equal to a minimum moving velocity and less than the maximum moving velocity at which cutting of the sheet metal is possible.

The present invention includes a laser-welded lap joint including a weld zone formed by laser lap welding in a lapped portion including a plurality of lapped steel sheets. The weld zone includes a main weld zone that penetrates the steel sheets in the lapped portion and a final weld zone formed at one end of the main weld zone and having a crater, and the weld zone satisfies formulas (1) to (4):
L≥15.0;  (1)
10.0≥L2≥2l.sub.c;  (2)
t1≥2d.sub.c;  (3)
w.sub.c>d.sub.c  (4).

A moving mechanism relatively moves a machining head emitting a laser beam, with respect to a sheet metal along a surface of the sheet metal. A beam vibrating mechanism vibrates the laser beam for irradiation on the sheet metal in a predetermined vibration pattern, while the machining head is relatively moved by the moving mechanism. A vibration control section controls the beam vibrating mechanism to progressively reduce an amplitude of the vibration pattern from a first position to a corner portion when the machining head moves toward the corner portion and reaches the first position before the corner portion by a predetermined distance, and progressively increase the amplitude of the vibration pattern until the machining head reaches a second position ahead of the corner portion by the predetermined distance from the corner portion, at a time of producing a product having the corner portion.

A fastening inclusion is provided and includes a hard point made of coalesced metal sheets, metal or fiber flanges extending from edges of the hard point, and a fastener arranged on the hard point. The fastening inclusion can be incorporated into a fiber reinforced polymer structure by interleaving the flanges with fiber reinforced resin plies, and then curing the fiber reinforced plies to form a composite structure. The fastener on the hard point may be used for mechanically connecting the composite structure to a separate component, such as a metal component on a vehicle.

A method for producing a precoated steel sheet (1) includes providing a precoated steel strip comprising a steel substrate (3) having, on at least one of its main faces, a precoating comprising an intermetallic alloy layer and a metallic alloy layer. The metallic alloy layer is a layer of aluminum, a layer of aluminum alloy or a layer of aluminum-based alloy. The method also includes laser cutting said precoated steel strip so as to obtain at least one precoated steel sheet (1) comprising a cut edge surface (13) resulting from the cutting operation. The cut edge surface (13) includes a substrate region (14) and a precoating region (15) and the thickness of the precoated steel sheet (1) is comprised between 0.8 mm and 5 mm. The laser cutting is carried out such that it results directly in a corrosion-improved zone (19) of the cut edge surface (13). The surface fraction of aluminum on the substrate region (14) of the corrosion-improved zone (19) is greater than or equal to 9% and the surface fraction of aluminum on the bottom half of the substrate region (14) of the corrosion-improved zone (19) is greater than or equal to 0.5%.

A control device controls a beam vibrating mechanism to vibrate a laser beam in a C-shaped vibration pattern in which a beam spot is moved from a first irradiation position at a front end in a cutting advancing direction to a second irradiation position at a rear side and displaced in an orthogonal direction to the cutting advancing direction, and is moved from the second irradiation position to a third irradiation position at a front end and displaced in the orthogonal direction to the cutting advancing direction, and movement from the first irradiation position to the third irradiation position via the second irradiation position, and movement from the third irradiation position to the first irradiation position via the second irradiation position are repeated. The control device performs control to cut the sheet metal by causing beam spots in the first to third irradiation positions to overlap one another.

Disclosed are methods of manufacturing a workpiece fixture (10) and also a target material fixture (10), for use in precision manufacturing processes. A sheet material is supported on a generic material fixture (10) and the sheet material precision processed to form support blades (16, 18) for a target workpiece fixture (10). Each support blade (16, 18) has a support locus and interstices are positioned in the support loci where a target pattern and the support loci coincide. Thus, there are no unnecessary clearances between the workpiece support (10) and the workpiece. The interstices that are present are located only where necessary to reduce or eliminate any interference between the precision manufacturing process and the fixture (10), when it is used in a precision process involving the target pattern.

A method for forming a large-diameter special-shaped cross section thin-wall tubular part. A tailor welded barrel blank is adopted as an original blank for forming of the large-diameter special-shaped cross section thin-wall tubular part. After a desired shape is formed, the original weld joint is removed and butt joint tailor welding is performed on the tubular part again. Since the tailor weld joint of the original barrel blank is removed from the final part, there is no need to consider the consistency or coordination of the microstructure of the weld joint and the base metal during the forming process and the subsequent thermal treatment process.