A welding determination device includes: a measurement unit configured to measure temperature of a joint portion between strip-shaped sheets (for example, steel strips (2)) to be joined by seam welding; and a determination unit configured to, based on measurement results by the measurement unit, calculate an average temperature T.sub.ave of the joint portion and a temperature difference T that is a difference between a maximum value and a minimum value among temperature of the joint portion and, when the average temperature T.sub.ave is less than or equal to a first threshold value and the temperature difference T is more than or equal to a second threshold value, determine that a joining defect due to ineffective current has occurred at the joint portion.

A welding apparatus including: a welding unit (20) that includes a pair of electrode wheels (21A, 21B) arranged to face each other with a welding object therebetween; a pressing unit (30) that includes a pair of press rolls (31A, 31B) that are arranged to face each other with the welding object therebetween and press a welded portion of the welding object welded by the electrode wheels (21A, 21B); a cooling unit (40) that supplies a cooling medium toward the welded portion pressed by the press rolls; a heating unit (50) that heats the welded portion cooled by the cooling unit (40); and a moving body (10) that supports the welding unit (20), the pressing unit (30), the cooling unit (40), and the heating unit (50), and reciprocates in a welding direction of the welding object.

A lithium-ion secondary-battery case that allows bonding without weld spatter and has high strength against external force acting on the battery case, and a method for manufacturing the lithium-ion secondary-battery case are provided. Specifically, an austenitic stainless steel foil is used for a cup component (2), and a two-phase stainless steel having an austenite transformation start temperature A.sub.C1 in a temperature increase process at 650 C. to 950 C. and an austenite and ferrite two-phase temperature range of 880 C. and higher, is used for a cover component (3), and the diffusion bonding is proceeded while accompanied by grain boundary movement upon transformation of the two-phase steel from a ferrite phase into an austenite phase within a heating temperature range of 880 C. to 1080 C.

A vacuum insulation panel manufacturing method that makes it possible to manufacture low-cost, high-performance vacuum insulation panels, and a vacuum insulation panel are provided. This method of manufacturing a vacuum insulation panel involves: a stacking step in which a first metal plate is stacked on one side of an insulating core material, and in which a backing member having an opening and a second metal plate having an evacuation port are stacked, with the opening and the evacuation port stacking, on the other surface of the core member in the order of backing member and second metal plate from the core member side; a first welding step for welding outwards of where the core member is arranged in the first metal plate and the second metal plate; an evacuating step from the evacuation port to create a vacuum in an inner area which is held between the first metal plate and the second metal plate and in which the core member is arranged; and a laser welding step in which, in a state in which the inner area is made into a vacuum by the evacuating step, the evacuation port is sealed by means of a sealing material and the sealing material, the second metal plate and the backing member are laser welded.

A vacuum insulation panel manufacturing method that makes it possible to manufacture low-cost, high-performance vacuum insulation panels, and a vacuum insulation panel are provided. This method of manufacturing a vacuum insulation panel (1) involves: a stacking step in which a first metal plate (20) is stacked on one side of an insulating core material (10), and in which a backing member (50) having an opening (51) and a second metal plate (30) having an evacuation port (32) are stacked, with the opening (51) and the evacuation port (32) stacking, on the other surface of the core member (10) in the order of backing member (50) and second metal plate (30) from the core member (10) side; a first welding step for welding outwards of where the core member (10) is arranged in the first metal plate (20) and the second metal plate (30); an evacuating step from the evacuation port (32) to create a vacuum in an inner area which is held between the first metal plate (20) and the second metal plate (30) and in which the core member (10) is arranged; and a laser welding step in which, in a state in which the inner area is made into a vacuum by the evacuating step, the evacuation port (32) is sealed by means of a sealing material (60) and the sealing material (60), the second metal plate (30) and the backing member (50) are laser welded.

An electrode orientation checking apparatus includes a machine stand attached to a seam welding apparatus from which one roller electrode of a set has been removed, a positioning guide and a set of distance sensors that are provided on the machine stand, and a calculating section. A positioning surface of the positioning guide is fixed at a position corresponding to a portion of an outer circumferential surface of the one roller electrode before being removed, the portion lying on a line segment connecting rotational centers of the roller electrodes. The distance sensors are respectively fixed forward and backward of the positioning surface in a progression direction of the roller electrodes. The calculating section calculates data for acquiring a direction of the line segment relative to the stacked body.

A vacuum insulation panel manufacturing method that makes it possible to manufacture low-cost, high-performance vacuum insulation panels, and a vacuum insulation panel are provided. This method of manufacturing a vacuum insulation panel involves: a stacking step in which a first metal plate is stacked on one side of an insulating core material, and in which a backing member having an opening and a second metal plate having an evacuation port are stacked, with the opening and the evacuation port stacking, on the other surface of the core member in the order of backing member and second metal plate from the core member side; a first welding step for welding outwards of where the core member is arranged in the first metal plate and the second metal plate; an evacuating step from the evacuation port to create a vacuum in an inner area which is held between the first metal plate and the second metal plate and in which the core member is arranged; and a laser welding step in which, in a state in which the inner area is made into a vacuum by the evacuating step, the evacuation port is sealed by means of a sealing material and the sealing material, the second metal plate and the backing member are laser welded.

The purpose is to determine occurrence of expulsion in seam welding with high accuracy. A welding determination device includes: a measurement unit configured to measure temperature of a joint portion between strip-shaped sheets (for example, steel strips) to be joined by seam welding; and a determination unit configured to, based on a measurement result by the measurement unit, calculate an average temperature T.sub.ave and a temperature difference T of the joint portion and, when the average temperature T.sub.ave is more than or equal to a first threshold value that is set according to the sheet thickness of each of the strip-shaped sheets and the temperature difference T is more than or equal to a second threshold value, determine that expulsion has occurred at the joint portion.

This seam-welding device carries out seam welding while repeating one cycle comprising a melting period, an interruption period, and a heating period implemented either before or after the interruption period. A welding current is applied between a pair of roller electrodes so as to form a welded part between workpieces during the melting period, the application of the current between the roller electrode pair is interrupted so as to solidify the welded part during the interruption period, and a heating current smaller than the welding current is applied between the roller electrode pair so as to heat the laminated body within a solidification temperature range of the welded part during the heating period. Consequently, even when the welding speed is increased, formation of cracks and spatter is effectively suppressed such that a high-quality joined product is obtained.

A method includes forming a first pocket in a first sheet of material and a second pocket in a second sheet of material, pressing the first pocket and the second pocket together at a nonlinear interface, and welding material of the first pocket and the second pocket at the interface.