Abstract: A resistance spot welded joint of an aluminum material is obtained by joining a stack of a plurality of aluminum materials by spot welding. A nugget formed by the spot welding includes a solidified part of the aluminum materials and a shell having a different solidification structure from the solidified part. The shell is formed annularly in a cross-section of the nugget in a stacking direction of the aluminum materials. The solidified part and the shell are alternately arranged from an outer edge of the nugget toward a nugget central part.

Abstract: The welding state detecting and transmitting device 40 is provided with a secondary battery 60 for accumulating power to be supplied to components within the device 40, a charging circuit 58 that utilizes a portion of the welding current to charge the secondary battery 60. A toroidal coil 42 is used for charging the secondary battery 60 with welding current. The troidal coil 42 is attached to secondary side conductor 32 and connected with the charging circuit 58. The device 40 wirelessly transmits data relating to the welding current detected by the toroidal coil 46. The device 40 substantially reduces the burden of maintenance of the device 40 required in prior art such as replacing a primary battery or recharging a rechargeable battery periodically.

Abstract: Welding controller 1 has CPU 1a, ROM1 1b, ROM2 1c and RAM 1d. Programs and data are written into the ROM1 1b and can be rewritten. Sequential welding data is written into the RAM 1d and can be rewritten. A write program for writing programs or data or sequential welding data into the ROM1 1b or the RAM 1d is stored in the ROM2 1c. When a welding control program or data or sequential welding data is input into the CPU 1a from an input device 10 or a computer 12, the CPU 1a executes the write program to write the inputted program or data or sequential welding data into the ROM1 1b or the RAM 1d. Preferably, ROM 1b is an in situ programmable memory, such as a flash memory or EEPROM.

Abstract: A single teaching apparatus may be provided for all welding control apparatus in a welding control apparatus in order to input the welding sequence data. The internal address of a welding control apparatus 22 and the welding sequence data are output to a field bus from an upper control apparatus 2. Programming is accomplished by storing the welding sequence data output from the upper control apparatus 2 in a designated address of memory unit 28. Programming of the welding control apparatus 22 can be accomplished: using the teaching apparatus 4 provided for the upper control apparatus 2.

Abstract: Resistance welding machines may include one or more temperature sensors that measure the temperatures of one or more heat generating elements within the welding machine, such as the welding transformer, the welding cable, the welding gun and/or the welding current switching element. These heat generating elements generate heat due to the passage of the welding current and can be damaged if not properly cooled. A processor is provided to receive temperature signals from the temperature sensors(s) and actuate a warning output circuit when the temperature of one or more of the heat generating elements rises to a high temperature warning temperature. This high temperature warning temperature is preferably lower than an upper limit temperature at or above which the heat generating element may be damaged due to overheating.

Abstract: A resistance welding controller for supplying a substantially constant level of AC current to a resistance welder is provided. In one embodiment, the resistance welding controller automatically switches modes to provide compatibility with both AC and DC resistance welders.

Abstract: A predetermined value is used for adjusting welding power to an optimum value to consistently achieve sturdy welds. The predetermined value is not affected by variations in workpiece materials and in wear of electrodes. Preferably, total power per unit volume of the workpieces is used as the predetermined value. In a resistance welding system, total power per unit volume required to satisfactorily weld the workpieces is calculated from a total thickness of the workpieces and a welding time. From this calculated total power per unit volume, power per unit volume and per unit time is calculated. The present welding system adjusts one of the welding current or the welding voltage to an optimum value required to produce the predetermined value.

Abstract: A resistance welder controller is disclosed, which controls a resistance welder for welding workpieces clamped between two electrodes with Joule heat generated by passing a welding current between the electrodes. The controller includes a preliminary current passing device for passing preliminary current between the electrodes until the workpieces and the electrodes become intimate with one another, a regular current passing device for passing regular current between the electrodes for welding the workpieces, a current control device for controlling the welding current according to the rate of expansion of the workpieces or the rate of increase of the resistance of the workpieces, and a current passing ending device for ending the welding current at or after an instant when the rate of expansion of the workpieces or the rate of increase of the resistance of the workpieces has become substantially zero.

Abstract: A resistance welding machine comprises clamping force representing value measuring means for measuring a clamping force representing value corresponding to a clamping force applied on workpieces by a pair of electrodes, clamping force representing value discriminating means for discriminating whether the clamping force representing value measured by the clamping force representing value measuring means is fluctuating or stabilized, and current supply means for supplying welding current through the electrode pair just after a stabilization timing when the clamping force representing value discriminating means discriminates that the clamping force representing value is stabilized.

Abstract: A controller for a welding machine in which workpieces are pinched between a pair of electrodes through which welding current is supplied to weld the workpieces, the controller includes a circuit for detecting an amount of resistance between the electrodes, a circuit for monitoring occurrence of a phenomenon that interelectrode resistance detected by the detecting circuit shifts from an upward tendency to a downward tendency, and a circuit for cutting off welding current after occurrence of the phenomenon monitored by the monitoring circuit, and when an absolute value of a time derivative of the interelectrode resistances detected by the detecting circuit becomes less than the predetermined value.

Abstract: A controller for a welding machine which requires no change of control programs, even if there is any change in material, thickness or others of workpieces is provided. After start of welding, welding current and/or pinching force increase, until there occurs a phenomenon that interelectrode resistance shifts from an upward tendency to a downward tendency, and thereafter the values at this time are maintained. The values are proper, and proper welding is performed. This is achieved, irrespective of material, thickness or others of the workpieces, so that there is no need of changing control programs one by one.

Abstract: A resistance welding machine includes a circuit for detecting a timing when the time derivative of primary winding current of a welding transformer becomes almost zero. The machine includes a circuit for measuring the primary winding current and primary winding voltage of the welding transformer, when the timing is detected by the timing detecting circuits. There is also for calculating a resistance of a secondary circuit from the primary winding current and y winding voltage measured by the measuring circuit as well as a characteristic value of the welding transformer.