A joining device includes: a first circuit in which a primary-side winding of a first transformer and a first capacitor are connected; a second circuit in which a primary-side winding of a second transformer and a second capacitor are connected; an electrode connected to secondary-side winding of the first transformer and secondary-side winding of the second transformer; and a charge switch configured to switch between energization/de-energization of the first and second capacitors from a power supply without the transformers being interposed. The first circuit has a first discharge switch and the second circuit has a second discharge switch. A method for manufacturing a joined object includes, by using the joining device, supplying an object to be joined to be sandwiched by the electrode; causing a current to flow through the electrode that sandwiches the object to be joined to join the object to be joined.

To provide a method and apparatus for manufacturing a joined member that inhibit occurrence of cracks in a joined member even when the joined portion is quenched when members are welded together. The method includes placing the first member D and the second member E with a joint target portion Df and a joint target portion Ef being in contact with each other, welding the joint target portions by heating, subjecting the first member D after the welding to a process for inhibiting occurrence of cracks, and tempering a portion where the first and second members have been welded to each other by electromagnetic heating. The apparatus includes a first electrode 11 to contact with the first member D; a second electrode 12 to contact with the second member E; and an induction heating coil 23 for performing induction heating of a portion where a joint target portions Df and Ef have been contacted and joined to each other, and the induction heating coil 23 is placed between the two electrodes 11 and 12 when the induction heating is performed.

A resistance welding apparatus can employ a modular power supply system with multiple power supply modules and leads for electrically connecting the modular power supply system to a welding resistor. The resistance welding apparatus is selectively configurable in at least three of (i) a first configuration in which the leads connect the first power supply module to the resistor and the second power supply module is disconnected from the resistor; (ii) a second configuration in which the leads connect the second power supply module to the resistor and the first power supply module is disconnected from the resistor; (iii) a third configuration in which the leads connect the first and second power supply modules to the resistor in series; and (iv) a fourth configuration in which the leads connect the first and second power supply modules to the resistor in parallel.

This disclosure relates to weldability of steel alloys that provide weld joints which retain hardness values in a heat affected zone adjacent to a fusion zone and which also have improved resistance to liquid metal embrittlement due to the presence of zinc coatings.

A resistance welder controller controls a welding current flowing through an inverter transformer, detects the welding current flowing through the inverter transformer, measures an energizing time and a point time interval of the detected welding current, calculates a usage rate of the inverter transformer using the energizing time and the point time interval, stores an equivalent current curve indicating a relationship between a current value of the welding current and the usage rate of the inverter transformer when the inverter transformer is operated at a rated capacity, and determines whether a relationship between the current value and the calculated usage rate of the inverter transformer exceeds the rated capacity of the inverter transformer based on the equivalent current curve, continues an operation when the relationship does not exceed the rated capacity of the inverter transformer, and stops the operation when the relationship exceeds the rated capacity of the inverter transformer.

A system for manufacturing a part, the system comprising a power source, a rectifier, an electrical conduit, and a framework. The power source is configured to generate a high frequency, high current electrical signal. The rectifier is configured to convert the electrical signal to a direct current electrical signal. The electrical conduit is configured to carry the electrical signal. The framework is formed of electrically resistive metal having a relatively high melting point and is connected to the electrical conduit and at least partially encased in a powdered metal having a melting point lower than the melting point of the framework so that transmission of the electrical signal through the framework transitions at least some of the powdered metal into its molten state so that at least some of the molten metal cooled into its solidified state forms at least a portion of the part.

There is provided a power supply device that supplies an output current to an electric processing device which performs electric processing on workpieces. The device includes: a first power supply; a magnetic energy recovery switch that receives a current supplied from the first power supply, and converts the received current into the output current; and a control unit that controls the magnetic energy recovery switch such that an electric current frequency of the output current includes a first electric current frequency and a second electric current frequency which are different from each other within a one-time electric processing time using the electric processing device.

In a resistance spot welding method, test welding and actual welding in which a current pattern is divided into two or more steps are performed. In the test welding, a constant current of a different value is passed in each step, and a time variation of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume are stored as a target value. In the subsequent actual welding, when a time variation amount of an instantaneous amount of heat generated per unit volume deviates during any step from the results of the test welding, a current passage amount is controlled to compensate for the difference during a remaining welding time in the step. In the test welding, 0.3×I.sub.x≦I.sub.a<I.sub.x, where I.sub.a is the current in the first step, and I.sub.x is the current in second and subsequent steps.

A ball forming device includes a first current control circuit to control discharge current arranged between a leading end of a wire and one electrode of a discharge continuing power source for causing discharge current to flow after dielectric breakdown, a second current control circuit to control shunting of discharge current arranged between a discharge electrode and the other electrode of the discharge continuing power source, and a fixed resistor connected to the second current control circuit in parallel as a shunt and controls current flowing through the second current control circuit, thereby a discharge voltage value is adequately changed.

An electrostatic energy storage welding machine for performing resistance welding while applying pressure to an object to be welded includes: a pair of welding electrodes; an energy storage section including a plurality of energy storage parts; an individual charge circuit for individually charging respective energy storage parts; an individual discharge circuit for individually discharging the respective energy storage parts; a voltage monitor circuit individually monitoring voltages of the respective energy storage parts; an individual voltage stabilization control section for performing control to further charge an energy storage part having deviation in performance in an individual manner to stabilize a voltage of that energy storage part and thereby achieve a set voltage; and an output circuit for outputting power produced by the set voltage stabilized through individual charging and electric current through individual discharging in the energy storage section to apply the electric current between the welding electrodes.