The present invention relates to a direct-contact type alternating current (AC) trapezoidal wave aluminum resistance welding process method. AC trapezoidal wave inverter controller capable of controlling a positive and negative half-wave current rising rate, and an AC transformer (no rectifier or silicon-controlled rectifier on a secondary coil of the transformer) with an output voltage of 10-30V, a peak current of 32-70 kiloampere and a frequency of 25-80 Hz are included. The inverter controller and the AC transformer are connected by means of a conductor, a welding electrode, a pressurization mechanism and a cooling system to form resistance welding equipment to enable the equipment to output positive and negative alternating trapezoidal wave current on two sides of the electrode when a workpiece is pressurized and welded and to perform welding according to a specified duty ratio, welding current, frequencies, welding cycle number and welding pressure. Practice proves that the method has the advantages that 50-150 welding spots can be welded while grinding the electrode once each time, service life of the electrode is prolonged by 2-5 times, production efficiency and welding quality are greatly improved, and production cost is reduced, thereby realizing a qualitative leap in aluminum and aluminum alloy resistance welding processes.

An apparatus and method for fastening layers of non-ferrous alloys, like aluminum, magnesium and copper utilizes a steel fastener and a spot welding machine. The fastener and metals are stacked and the heat from the welder's electric current softens the lower melting point aluminum allowing the fastener to penetrate the aluminum. A weld zone between the fastener and the various layers creates an internal weld. The fastener has a rough shaft that is coated by the molten weld zone and is hard to withdraw on solidification. Layers of non-conductive materials like plastics and ceramics may also be affixed to a conductive layer using a fastener made from a compatible material that extends through a pilot hole and welds to or penetrates a conductive layer. The fastener may have projections that initially reduce contact area with the stack.

A welding electrode for an electric resistance welding process. The welding electrode includes a body extending along a center axis and terminating axially at a weld face for contacting a work face. The weld face defines a center along the axis and defines an outer edge spaced radially from the center. A plurality of senates are defined along the weld face. Each of the serrates projects axially away from the weld face and extends radially from the center axis to the outer edge of the weld face. A higher density of the plurality of serrates is formed proximate to the center axis than proximate to the outer circumference of the weld face. Methods for using the welding electrode and forming the senates on the welding electrode are also provided.

Aluminum-base alloy workpieces have surfaces with films of aluminum oxide which inhibit good contact with weld faces of resistance spot weld electrodes and the faying surfaces of, for example, sheet workpieces stacked for welding. Sometimes, the surfaces of the sheets also are coated with an adhesive or a sealer which further complicates welding. But in accordance with this invention, weld faces of opposing, round, copper welding electrodes are pressed against opposite outside surfaces of the sheets at a spot weld site and weld current is applied to the electrodes in accordance with a three-stage weld schedule to better form each weld. The weld schedule comprises a Conditioning stage (stage 1), a weld nugget Shaping stage (stage 2), and a weld nugget Sizing stage (stage 3).

A welding assembly including a current generator, a first electrode electrically coupled to the current generator, the first electrode including a first engagement surface, a second electrode electrically coupled to the current generator, the second electrode including a second engagement surface, a width-determining fixture positioned between the first electrode and the second electrode to define a welding volume having a width, and an electrically nonconductive material positioned to electrically insulate at least one of the first electrode and the second electrode from an electrical conductor outside the width.

Aluminum-base alloy workpieces have surfaces with films of aluminum oxide which inhibit good contact with weld faces of resistance spot weld electrodes and the faying surfaces of, for example, sheet workpieces stacked for welding. Sometimes, the surfaces of the sheets also are coated with an adhesive or a sealer which further complicates welding. But in accordance with this invention, weld faces of opposing, round, copper welding electrodes are pressed against opposite outside surfaces of the sheets at a spot weld site and weld current is applied to the electrodes in accordance with a three-stage weld schedule to better form each weld. The weld schedule comprises a Conditioning stage (stage 1), a weld nugget Shaping stage (stage 2), and a weld nugget Sizing stage (stage 3).

Disclosed are welds formed from improved resistance spot welding. Resistance spot welding includes positioning a first metal sheet and a second metal sheet between two electrodes, contacting the two electrodes together on to opposing surfaces of the first metal sheet and the second metal sheet, and applying at least a minimum current to the first metal sheet and the second metal sheet through the two electrodes to form a weld having a minimum weld size to join the first metal sheet with the second metal sheet. At least one of the first metal sheet and the second metal sheet is a fusion alloy where the composition of at least one outer layer of the sheet is different from the composition of the core of the sheet.

A bonded body is provided that is formed by bonding a metal member formed from copper, nickel, or silver, and an aluminum alloy member formed from an aluminum alloy of which a solidus temperature is lower than a eutectic temperature of aluminum and a metal element that constitutes the metal member. The aluminum alloy member and the metal member are subjected to solid-phase diffusion bonding. A chill layer, in which a Si phase of which an aspect ratio of a crystal grain is 2.5 or less and a crystal grain diameter is 15 m or less is dispersed, is formed on a bonding interface side with the metal member in the aluminum alloy member. The thickness of the chill layer is set to 50 m or greater.

A welding assembly including a current generator, a first electrode electrically coupled to the current generator, the first electrode including a first engagement surface, a second electrode electrically coupled to the current generator, the second electrode including a second engagement surface, a width-determining fixture positioned between the first electrode and the second electrode to define a welding volume having a width, and an electrically nonconductive material positioned to electrically insulate at least one of the first electrode and the second electrode from an electrical conductor outside the width.

A spot welding apparatus includes a spot welding gun and a welding gun control apparatus. The welding gun control apparatus includes a pressurizing force control part controlling the pressurizing force, a position control part controlling the position of at least one electrode, and a determination part determining whether or not the welding is performed in a normal state. The position control part controls an electrode drive motor so as to hold the electrodes, after the supply of the electric current is started, at positions when the initial pressurizing force is applied before the electric current is supplied. The determination part acquires the pressurizing force and determines whether or not the welding is performed in a normal state based on change tendency in the pressurizing force.