An ultrasonic resistance welding apparatus 10 contains a resistance spot welding apparatus 15, a first electrode 16 and a vibrable second electrode 18, the vibrable second electrode 18 in operable communication with an ultrasonic transducer 12, whereby the ultrasonic transducer 12 selectively imparts vibratory energy to the vibrable second electrode 18 based on signals from a controller 32. The vibrable second electrode 18 may be tuned or designed to resonate within 2.5% of an operating frequency of the ultrasonic transducer 12. During operation of the welding apparatus 10, a tip 19 of the second vibrable electrode 18 may be positioned at an anti-nodal point 38 of the vibratory energy and the vibrable second electrode 18 may be attached to the resistance spot welding apparatus 15 at a nodal plane 36 of the vibratory energy. A process for employing the apparatus 10 is also presented.

An ultrasonic resistance welding apparatus 10 contains a resistance spot welding apparatus 15, a first electrode 16 and a vibrable second electrode 18, the vibrable second electrode 18 in operable communication with an ultrasonic transducer 12, whereby the ultrasonic transducer 12 selectively imparts vibratory energy to the vibrable second electrode 18 based on signals from a controller 32. The vibrable second electrode 18 may be tuned or designed to resonate within 2.5% of an operating frequency of the ultrasonic transducer 12. During operation of the welding apparatus 10, a tip 19 of the second vibrable electrode 18 may be positioned at an anti-nodal point 38 of the vibratory energy and the vibrable second electrode 18 may be attached to the resistance spot welding apparatus 15 at a nodal plane 36 of the vibratory energy. A process for employing the apparatus 10 is also presented.

A method for manufacturing a turbo fan unit includes a step for preparing multiple fan blades and an other-side side plate, and a step for connecting each of the multiple fan blades to the other-side side plate by a welding process. In the preparing step, one of the fan blade and the side plate is prepared, in which a connecting-surface forming portion having a connecting surface and a welding projection protruded from the connecting surface is formed. The connecting surface connects one of the fan blade and the side plate to the other one of the fan blade and the side plate. In the connecting step, the welding projection is melted down and the connecting surface is connected to an opposing surface, which is the surface of one of the fan blade and the side plate and which is opposing to the connecting surface.

A method for welding multiple workpieces together includes applying a force to the multiple workpieces, generating ultrasonic vibration, transferring the ultrasonic vibration to the multiple workpieces to breakdown an oxide layer, generating an electric current, transmitting the electric current to heat up the workpieces, and synchronizing the ultrasonic and resistance heating operations. A welding system includes an ultrasonic vibration unit that generates an ultrasonic vibration and transfers the ultrasonic vibration to multiple workpieces to breakdown an oxide layer, a resistance heating unit that generates an electric current and transmits the electric current to heat up the workpieces, a workpiece mount that includes electrodes configured to receive the generated current and/or clamp the multiple workpieces during a welding process, and a controller configured to synchronize an operation of the ultrasonic vibration unit and an operation of a resistance heating unit.

A method for welding multiple workpieces together includes applying a force to the multiple workpieces, generating ultrasonic vibration, transferring the ultrasonic vibration to the multiple workpieces to breakdown an oxide layer, generating an electric current, transmitting the electric current to heat up the workpieces, and synchronizing the ultrasonic and resistance heating operations. A welding system includes an ultrasonic vibration unit that generates an ultrasonic vibration and transfers the ultrasonic vibration to multiple workpieces to breakdown an oxide layer, a resistance heating unit that generates an electric current and transmits the electric current to heat up the workpieces, a workpiece mount that includes electrodes configured to receive the generated current and/or clamp the multiple workpieces during a welding process, and a controller configured to synchronize an operation of the ultrasonic vibration unit and an operation of a resistance heating unit.

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.

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.

The present invention has as its object to provide a spot welded joint and spot welding method which raise the fracture toughness of spot welded metal to raise the strength of the spot welded joint. In the present invention, there is provided a spot welding method comprising a melt zone forming step forming a melt zone by conduction and, after the melt zone forming step, a solidification step of running a current lower than the current run in the melt zone forming step so as to cause the melt zone to solidify, wherein, in the solidification step, electromagnetic vibration is applied to the melt zone, and a frequency f.sub.V of the electromagnetic vibration, a solidification speed .sub.S when the melt zone solidifies, and an arm interval of dendrites .sub.D when the melt zone solidifies satisfy 0.2.sub.S/(.sub.D.Math.f.sub.V)4.0.

The present invention has as its object to provide a spot welded joint and spot welding method which raise the fracture toughness of spot welded metal to raise the strength of the spot welded joint. In the present invention, there is provided a spot welding method comprising a melt zone forming step forming a melt zone by conduction and, after the melt zone forming step, a solidification step of running a current lower than the current run in the melt zone forming step so as to cause the melt zone to solidify, wherein, in the solidification step, electromagnetic vibration is applied to the melt zone, and a frequency f.sub.V of the electromagnetic vibration, a solidification speed .sub.S when the melt zone solidifies, and an arm interval of dendrites .sub.D when the melt zone solidifies satisfy 0.2.sub.S/(.sub.D.Math.f.sub.V)4.0.

A method for manufacturing a turbo fan unit includes a step for preparing multiple fan blades and an other-side side plate, and a step for connecting each of the multiple fan blades to the other-side side plate by a welding process. In the preparing step, one of the fan blade and the side plate is prepared, in which a connecting-surface forming portion having a connecting surface and a welding projection protruded from the connecting surface is formed. The connecting surface connects one of the fan blade and the side plate to the other one of the fan blade and the side plate. In the connecting step, the welding projection is melted down and the connecting surface is connected to an opposing surface, which is the surface of one of the fan blade and the side plate and which is opposing to the connecting surface.