A workpiece of Ti or a Ti alloy includes a surface with a coating layer of titanium nitride. A region of the surface includes a connection zone of a Ti—N solid solution alloy. A second Ti or Ti alloy workpiece is contacted with the connection zone, and a weld joint is formed across the connection zone with a resistance welding process. The weld joint extends into the first Ti workpiece and the second Ti workpiece.

The present disclosure discloses a button cell, and a method for welding electrode tabs to a pole shell of the button cell. The button cell includes the pole shell and an electric core. The pole shell consists of an anode shell and a cathode shell. The button cell further comprises at least one metal sheet. A cathode tab and/or an anode tab of the electric core is/are welded to the metal sheet, and the metal sheet is then welded to the cathode shell and/or the anode shell. The button cell manufactured by the invention has a complete surface, and can avoid phenomena such as electrolyte leakage and surface bulging caused by the rupture of the polar shell.

Provided are a three-dimensional shaped object production device and method capable of producing a predetermined three-dimensional shaped object by forming a ball at a leading end of a conductive wire through use of the conductive wire based on scanned data or designed data and aligning and stacking the balls. The three-dimensional shaped object production device includes: a plate (40), on which a three-dimensional shaped object is placeable; a ball forming section configured to form a ball (13) by applying high voltage between a leading end of a conductive wire (4) paid out from a leading end of a capillary (12) and a spark rod (19) and melting the leading end of the wire by discharge energy; a positioning device configured to position the plate and the ball forming section by moving the plate and the ball forming section relative to each other; and a bonding section configured to bond the ball formed at the leading end of the capillary to another ball (14) that has already been stacked on the plate, the forming of the ball by the ball forming section, the relative moving of the plate and the ball forming section by the positioning device, and the bonding of the ball formed at the leading end of the capillary to the another ball by the bonding section is repeated, to thereby produce a three-dimensional shaped object having a desired shape.

A resistance spot welding method includes sandwiching metal plates put on top of one another between a pair of electrodes and performing resistance spot welding sequentially on a plurality of welding points close to each other on the metal plates by performing a current application between the electrodes so as to join the metal plates to each other. A welding current value to form a welding nugget at a welding point to be subjected to the resistance spot welding second or later among the welding points is set to be higher than a first welding current value to form a first welding nugget at a first welding point to be subjected to the resistance spot welding first among the welding points.

A welding process used in a method of manufacturing a steel sheet assembly includes spot welding steel sheets performed for a heat time of 0.08 seconds or more using a convex electrode with a tip radius of curvature of 20 mm or more or a flat electrode such that the weld force F (kN) for initial 0.03 seconds of the heat time satisfies formula: F<0.00125×(1+0.75×t.sub.all)+3 where TS (MPa) denotes an average strength of the steel sheets and represents a weighted mean value of a thickness of each of the steel sheets, and t.sub.all (mm) denotes a total thickness of the steel sheets (the sum of the thicknesses of the steel sheets).

A welding process used in a method of manufacturing a steel sheet assembly includes spot welding steel sheets performed for a heat time of 0.08 seconds or more using a convex electrode with a tip radius of curvature of 20 mm or more or a flat electrode such that the weld force F (kN) for initial 0.03 seconds of the heat time satisfies formula: F<0.00125×(1+0.75×t.sub.all)+3 where TS (MPa) denotes an average strength of the steel sheets and represents a weighted mean value of a thickness of each of the steel sheets, and t.sub.all (mm) denotes a total thickness of the steel sheets (the sum of the thicknesses of the steel sheets).

A method for welding a stack of sheets having a plurality of sheets of different materials is provided. In an aspect, the stack of sheets includes an aluminum sheet and a galvanneal steel sheet. In an aspect, the method includes resistively spot welding the galvanneal sheet to a hot-stamped steel sheet placed between the aluminum sheet and the galvanneal sheet, the sheet of hot-stamped steel including stress relief sections. The method further includes placing a metal foil on the aluminum sheet and vaporizing the metal foil to project portions of the aluminum sheet through the stress relief sections of the hot-stamped steel sheet to weld the portions of the aluminum sheet to the galvanized steel sheet. In another aspect, the method includes placing the metal foil on a raised portion of the aluminum sheet and projecting the raised portion of the aluminum onto the galvanneal steel sheet.

A ring forming step includes welding opposite ends of a band saw blade including a body part having a band shape, and a tooth part including a plurality of teeth formed on one side part of the body part, to form a ring shape. A polishing step includes polishing an inner surface, an outer surface, and an end face on a side opposite to the tooth part in the ring-shaped band saw blade subjected to the ring formation. A tip tooth tip forming step includes positioning, after the polishing step, the ring-shaped band saw blade subjected to the ring formation by use of one of the inner surface and the outer surface, and the end face as references, joining a cutting tip to tooth tips of the plurality of teeth by welding, and polishing the joined cutting tip to form a tooth tip shape.

A ring forming step includes welding opposite ends of a band saw blade including a body part having a band shape, and a tooth part including a plurality of teeth formed on one side part of the body part, to form a ring shape. A polishing step includes polishing an inner surface, an outer surface, and an end face on a side opposite to the tooth part in the ring-shaped band saw blade subjected to the ring formation. A tip tooth tip forming step includes positioning, after the polishing step, the ring-shaped band saw blade subjected to the ring formation by use of one of the inner surface and the outer surface, and the end face as references, joining a cutting tip to tooth tips of the plurality of teeth by welding, and polishing the joined cutting tip to form a tooth tip shape.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in subsequent current passage in the test welding, current passage is performed by constant current control under a condition: 0.5≤Vtp/Vtm≤2.0 when tc<800 ms; 0.5−0.3×(tc−800)/800≤Vtp/Vtm≤2.0−0.5×(tc−800)/800 when 800 ms≤tc<1600 ms; and 0.2≤Vtp/Vtm≤1.5 when tc≥1600 ms, where Vtm is an average value of a voltage between the electrodes in main current passage in the test welding, and Vtp is an average value of a voltage between the electrodes in the subsequent current passage in the test welding, and wherein in main current passage in the actual welding, adaptive control welding is performed, and in subsequent current passage in the actual welding, current passage is performed by constant current control under a condition: 0.8×Itp≤Imp≤1.2×Itp, where Itp is a current in the subsequent current passage in the test welding, and Imp is a current in the subsequent current passage in the actual welding.