An electric resistance welder that includes a compressor, a welding holder, and a welding rod is provided. Air compressed by the compressor may be introduced into the welding rod through the welding holder and is then discharged through air outlets formed in the welding rod.

A method of spot welding a workpiece stack-up that includes a steel workpiece and an aluminum alloy workpiece involves passing an electrical current through the workpieces and between welding electrodes that are constructed to affect the current density of the electrical current. The welding electrodes, more specifically, are constructed to render the density of the electrical current greater in the steel workpiece than in the aluminum alloy workpiece. This difference in current densities can be accomplished by passing, at least initially, the electrical current between a weld face of the welding electrode in contact with the steel workpiece and a perimeter region of a weld face of the welding electrode in contact with the aluminum alloy workpiece.

A welding station includes a welding gun that includes first and second caps. The welding gun is movable between a working position and a maintenance position. The working position corresponds to a welding operation on at least one workpiece. A maintenance tool assembly is configured to cooperate with the first and second caps in the maintenance position. The maintenance tool assembly includes a cap extractor, a cap dispenser and a cap dresser. The cap extractor is configured to remove the first and second caps from the welding gun. The cap dispenser is configured to provide a new cap to the welding gun for installation. The cap dresser is configured to shape the cap face. The maintenance tool assembly includes a lift actuator. A translate actuator is respectively configured to move the maintenance tool assembly in the lift and translate directions with respect to the welding gun.

An electrical resistance spot welding electrode is disclosed for contact with a narrow or other selected spot weld region in a steel workpiece in a stack-up with an aluminum alloy workpiece for use in a spot welding method in which the weld nugget is carefully formed in the aluminum workpiece at the interface of the stack-up. The welding face of the welding electrode for contact with the steel workpiece is shaped with an aspect ratio greater than one, which fits against the contact surface of the steel workpiece, while the welding face for the aluminum-contacting weld electrode is circular (with an aspect ratio equal to one). The stack-up of workpieces may include a single steel workpiece facing two aluminum workpieces in a sandwich type stack-up or two steel workpieces facing a single aluminum workpiece with the outer steel workpiece having the narrow contact surface for the steel welding electrode.

To accurately make a dressing quality determination based on resistance waveforms, a dressing quality determination method determines the quality of dressing performed for electrodes when resistance welding is performed at a plurality of welding points. This method includes accumulating a known resistance waveform immediately after dressing the electrodes, and a known resistance waveform immediately before dressing the electrodes; creating, by a statistical method, a model for setting a threshold value for dressing quality determination, based on a plurality of known resistance waveforms immediately after dressing and a plurality of known resistance waveforms immediately before dressing; acquiring an unknown resistance waveform immediately after dressing the electrodes; and determining whether dressing is normal or dressing is abnormal by comparing the unknown resistance waveform immediately after dressing with the threshold value for dressing quality determination.

Structures for a tool surface of a downhole tool are constructed from a metal clay molded in a wet state. The wet state clay is a workable combination that can have a braze alloy grain, a tungsten carbide grain, and a binder. Additional cutting inserts can be embedded in the molded clay. Heat treatment applied to the molded metal clay causing the binder to be combusted and consumed. The braze alloy melts and then cools into a fused state with the tungsten carbide grain therein. The structure can affix to the tool surface of the tool by first being fused and then attached by brazing to the tool. Alternatively, the structure can be positioned in a fusible state adjacent the tool surface. When the heat treatment is applied, the structure fuses together and forms a metallurgical bond with the tool surface of the tool.

Structures for a tool surface of a downhole tool are constructed from a metal clay molded in a wet state. The wet state clay is a workable combination that can have a braze alloy grain, a tungsten carbide grain, and a binder. Additional cutting inserts can be embedded in the molded clay. Heat treatment applied to the molded metal clay causing the binder to be combusted and consumed. The braze alloy melts and then cools into a fused state with the tungsten carbide grain therein. The structure can affix to the tool surface of the tool by first being fused and then attached by brazing to the tool. Alternatively, the structure can be positioned in a fusible state adjacent the tool surface. When the heat treatment is applied, the structure fuses together and forms a metallurgical bond with the tool surface of the tool.

An apparatus includes a housing, a pin, a mechanism and a sensor. The housing is configured to receive a weld head. The pin is configured to move linearly relative to said housing. The mechanism is configured to convert a position of said pin into a displacement. The sensor is configured to generate a value representative of said position of said pin based on said displacement.

When a drive unit 5 drives to rotate a first rotator 6 and a second rotator 7 relative to one another in a first relative positional relationship R1 toward one side, graspers 8 turn toward the one side to cause respective pawl portions 8c to advance into a detachment operation space S1 such that the pawl portions 8c can contact an electrode 10 set in the detachment operation space S1, and when the drive unit drives to rotate the first rotator 6 and the second rotator 7 relative to one another in a second relative positional relationship R2 toward another side, the graspers 8 turn toward the other side to cause the respective pawl portions 8c to advance into the detachment operation space S1 such that the pawl portions 8c can contact an electrode 10 set in the detachment operation space S1.

A bonding probe is used for bonding a cover sheet to a core to form or repair a dual wall structure. The bonding probe includes a body, an attachment end at a distal end of the body, a head at an opposite end of the body, a tip extending from the head, and a cooling passageway. The attachment end couples the body to a resistance welder. The tip extends to form a proximate end of the body. The tip includes a contacting area having a predetermined three dimensional contoured surface. The contacting area aligns with a predetermined area of a three dimensional outer surface of a cover sheet of a dual walled structure. The cooling passageway provides a passageway for a flow of cooling fluid. The cooling passageway extends through the head, and into the tip.