The present disclosure generally relates to a welding machine adapted for performing a spot welding process on a workpiece, wherein the welding machine is specifically adapted for automatically applying pre-conditioning a welding pulse portion to the workpiece prior to performing the spot welding process. The present disclosure also relates to a corresponding method and computer program product.

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).

This spot welding method is a method for joining workpieces being a layered body of three or more metal sheets by supplying welding current. The welding current has a pulse-like waveform wherein a peak state in which the current reaches or is maintained to be within a set peak current range and a non-peak state in which the current is lowered from the peak current range to a set bottom current, and is then increased toward the peak current range again are alternately achieved. In the non-peak state, in the case where an effective value Irms of the welding current is lowered, and reaches a predetermined effective value target range, a current control process for increasing the welding current toward the peak current range is started.

Provided is a setting assistance device capable of informing that which welding condition should be corrected with a value as the limit in order to achieve the target quality. In a setting assistance device (40) of a welding condition which is a condition in welding, an input receiving unit (42) accepts designation of the target quality in welding, and a welding condition information output unit (44) outputs an item of a welding condition to be corrected to achieve the target quality, and limit information indicating a limit of a value which can be taken by the item of the welding condition to achieve the target quality, in accordance with the acceptance of the designation of the target quality by the input receiving unit (42).

To provide a spot welding system of high reliability which, when an abnormality such as a spot missing in spot welding occurs, is capable of more precisely and accurately detecting this immediately. Provided are a robot-side system having a robot and a robot-side control unit which controls driving of the robot; and a welder-side system having a welding gun mounted to the robot, and a welder-side control unit, in which the robot-side system includes: a storage unit which stores in advance a required welding time needed in a sport welding operation of one location or a plurality of spot welding operations; a welding time measurement unit which measures an actual time from when a welding start command is outputted until receiving a welding completion command; and a comparative determination unit which determines quality by comparing the required welding time stored in the storage unit and the actual welding time measured by the welding time measurement unit.

A resistance welding apparatus includes a welding controller configured to control a welding tool. The welding controller has an assignment device including a parametrization device. The assignment device is configured to read out a current point to be welded from a list of points to be welded, to read out a first setpoint curve from a record of a database assigned to the current point to be welded, and to assign the first setpoint curve to the first regulator and the parametrization device is configured to read out the first value from the record of the point to be currently welded and to parametrize a first parameter of the first regulator with the first value. The welding controller further includes the first regulator configured, using a first parameter, to regulate a temporal profile of an electric current at the current point to be welded in accordance with the first setpoint curve.

A resistance spot welding method able to form a welded joint having delayed fracture resistance, includes, in order, applying a pressing force P1 (kN) to the plurality of steel sheets by welding electrodes while supplying a supplied current I1 (kA), while applying the pressing force P1, supplying a current Ic (kA) during a cooling time tc (s), repeating two times or more a pressure force raising and lowering cycle of supplying a supplied current I2 (kA) to the welding electrodes while applying a pressing force P2 (kN) to the plurality of steel sheets by the welding electrodes during a pressing time tf (s), then immediately applying a pressing force P3 (kN) during a pressing time ti (s), applying the pressing force P2 during the pressing time tf, and releasing the pressing force and ending the supply of current, satisfying 0Ic<I1, 0.3I2/I1<1.0, P2/P12, tf0.2, P3<P2, and ti0.2.

A resistance-spot-welded aluminum joint having a type of a nugget that can reduce variations in cross tension strength. The resistance-spot-welded aluminum joint is obtained by layering a plurality of aluminum members and welding the aluminum members together by resistance spot welding. In a cross section of an interface between the aluminum members, a weld nugget formed as a result of the resistance spot welding has a plurality of blowholes aggregated in a central area of the weld nugget within the interface. In a cross section taken in a layered direction of the aluminum members extending through the center of the weld nugget, a blowhole with a maximum size of the plurality of blowholes is formed at a position where the blowhole extends through a center line of the weld nugget extending in the layered direction.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding. The test welding is performed under each of two or more welding conditions. In the actual welding, preliminary current passage is performed by constant current control in the same current pattern as in the preliminary current passage of the test welding, an electrical property between the electrodes in the preliminary current passage in the actual welding and an electrical property between the electrodes stored in the preliminary current passage in the test welding are compared for each welding condition to set a target in main current passage in the actual welding, and thereafter adaptive control welding is performed to control a current passage amount as the main current passage.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein the test welding is performed under each of two or more welding conditions. In the test welding, for each of the welding conditions, an electrode force parameter from when electrode force application to parts to be welded starts to when a set electrode force is reached before start of current passage and a time variation curve of an instantaneous amount of heat generated and a cumulative amount of heat generated are stored. In the actual welding: electrode force application to the parts to be welded is performed under each of the same conditions as in the test welding before start of current passage, and a corresponding electrode force parameter and the parameter stored in the test welding are compared for each of the welding conditions to set a target of a time variation curve of an instantaneous amount of heat generated and a cumulative amount of heat generated in the actual welding; and adaptive control welding is performed to control a current passage amount according to the target.