JFE Steel Corporation

A laser cutting method is for cutting, using a laser cutter, the vicinity of a joint ( 2 ) at which a trailing end of a preceding steel strip ( 1 A) is joined to a leading end of a succeeding steel strip ( 1 B), and includes an edge position detection process of detecting an edge position of the preceding steel strip and of the succeeding steel strip, a cutting track determination process, and a cutting execution process. In the cutting track, an oscillation start position of a laser is set outward from the edge position by a first predetermined distance in a width direction of the steel strip, an oscillation end position of the laser is set outward from the edge position by a second predetermined distance in the width direction of the steel strip, and a penetration angle of the laser is set to a predetermined angle or less.

A machining system 1 comprises: a machining device 10 configured to process a target material 80 containing a removal target 82 ; and a control device 12 configured to generate a motion trajectory 41 of the machining device 10 for removing the removal target 82 based on a three-dimensional shape and posture of the target material 80 and a position and shape of the removal target 82 , and move the machining device 10 based on the motion trajectory 41 . The control device 12 is configured to generate, as the motion trajectory 41 , a path along which the machining device 10 approaches a base shape of the target material 80 while rotating around an outside of the target material 80 or a path along which the machining device 10 approaches the base shape of the target material 80 while rotating around an inside of the target material 80 .

A laser welding method for preventing cracking and obtaining a weld joint of a weld metal with excellent toughness, and a laser weld joint. The laser welding method includes butting steel material members, the steel material having a chemical composition including, in mass %, C: 0.04 to 0.15%, Si: 0.05 to 1.00%, Mn: 0.50 to 2.50%, P: 0.030% or less, S: 0.020% or less, Al: 0.050% or less, Ti: 0.050% or less, O: 0.010% or less, and N: 0.008% or less, and having a carbon equivalent Ceq, represented by the following Expression (1), of 0.30 to 0.45, with the balance being Fe and unavoidable impurities, covering a portion on the surfaces of the steel material members including a weld line with flux having a predetermined composition, and performing laser welding thereon to produce a weld joint. Ceq=[C]+[Mn]/6+[Si]/24+[Cu]/20+[Ni]/40+[Cr]/5+[Mo]/4  (1)

Provided are cutting equipment for steel strips and a cold rolling line that allow for accurate laser cutting of joint portions between continuous steel strips. The cutting equipment for steel strips ( 1 ) includes: a joint portion detection device ( 5 ) configured to detect a joint portion ( 2 ) in which a rear end of a preceding steel strip and a front end of a succeeding steel strip are joined; an end portion detection device ( 6 ) configured to detect end portions of the steel strips; a vibration prevention device ( 7 ) configured to prevent vibration of the steel strips; and a cutting device ( 4 ) configured to laser cut a vicinity of the joint portion, wherein the end portion detection device and the vibration prevention device are provided on separate stands from each other.

Cutting equipment for steel strips ( 1 ), the cutting equipment including: a cutting device ( 4 ) configured to laser cut a vicinity of a joint portion ( 2 ) in which a rear end of a preceding steel strip and a front end of a succeeding steel strip are joined that has been detected by a joint portion detection device ( 5 ), and a vicinity of a defective portion of the steel strips that has been detected by a defect detection device ( 8 ); and a control unit ( 9 ), wherein the control unit includes a plurality of modes, including a first cut mode that causes laser cutting in the vicinity of the joint portion, and a second cut mode that causes laser cutting in the vicinity of the defective portion, and the control unit operates the cutting device in accordance with one cut mode in the plurality of modes.

A laser-beam butt welding method is provided in which cut surfaces of two steel sheets each having a sheet thickness t of 0.1 to 3.0 mm are placed in contact with each other and butted together, and then the two steel sheets are welded together by feeding a filler to the butted part and emitting a laser beam onto the butted part so as to melt the filler and the steel sheets. In this method, the cut surfaces of the two steel sheets are formed by laser cutting so as to have inclination angles θ exceeding 20° but not exceeding 60° in the same direction relative to a plane perpendicular to surfaces of the steel sheets, and to have a width a of 3.0 mm or less in a steel-sheet longitudinal direction, and then the cut surfaces of the two steel sheets are butted together in a state of a scarf joint and welded together. Thus, a high-quality butt-weld joint can be produced even in thin steel sheets having a small sheet thickness and a large width.

Provided is a laser machining method that causes no degradation in magnetic properties for thin electrical steel sheets. An electrical steel sheet machining method comprises machining an electrical steel sheet to a predetermined shape by melt-cutting the electrical steel sheet using a laser, wherein a scanning rate of the laser in the melt-cutting is 10000 mm/min or more.

A laser beam welding method is disclosed that includes irradiating a gap between butted steel sheets with a laser beam while supplying a filler to the gap so as to cause butted portions of the steel sheets and the filler to melt and solidify, and thus form a weld metal, thereby melting and joining the butted steel sheets. The method includes delivering the laser beam while rotating it across the gap between the steel sheets and controlling the ratio of the amount of the filler supplied to the gap per unit time to the volume of the gap between the steel sheets to be welded per unit time to be within a predetermined range. Also disclosed are a welding machine used for the method and a weld joint obtained with the method.

A laser welding method is disclosed including butting Si-containing steel sheets and irradiating a gap between the butted steel sheets with a laser beam while feeding a filler wire to the gap thereby melting and solidifying the filler wire and the butted steel sheets to form a weld metal, and thus joining the butted steel sheets together, in which an austenitic wire is used as the filler wire, the width of the gap is set to 0.30 mm or more, and the amount of the filler wire fed to the gap per unit welding length is set within the range of 1.5 to 2.5 times the volume of the gap per unit length, so that a weld metal with an austenite structure is stably obtained. Preferably, the base metal dilution ratio of the weld metal is set to 70% or less.

A laser cutting method for a steel strip, includes cutting an end in a width direction of the steel strip including a joint obtained by joining a rear end of a preceding steel strip and a front end of a following steel strip by using a laser beam, wherein the steel strip is cut such that an interval between pieces of dross having an aspect ratio of 1.0 or more is set to 1.0 mm or more and an interval between dross having an aspect ratio of 1.0 or more and dross having an aspect ratio of less than 1.0 is set to 1.0 mm or more in the end in the width direction after cutting.