Method of controlling welding conditions of a resistance welder

A method for controlling welding conditions of a resistance welder by using a heat conduction simulator, said heat conduction simulator performing simulation of a welding portion on the basis of heat conduction calculation from detected values of a welding current and a chip-to-chip voltage, said method comprising the steps of:

• estimating a status quantity expressing a nugget-forming state during welding in said welding portion by said heat conduction simulator;
• comparing said status quantity with a reference status quantity at the time of estimation, said reference status being determined on the basis of a monitored value expressing the state of welding;
• and
• on the basis of the result of comparison, correcting the welding conditions, while modifying at least one of a configuration of said heat conduction simulator and a numerical value of said heat conduction simulator so as to make said status quantity coincide with said reference status quantity.

An apparatus for controlling welding conditions of a resistance welder by using a heat conduction simulator, said heat conduction simulator performing simulation of a welding portion on the basis of heat conduction calculation from detected values of a welding current and a chip-to-chip voltage, said apparatus comprising:

• means for estimating a status quantity expressing a nugget-forming state during welding in said welding portion by said heat conduction simulator;
• means for comparing said status quantity with a reference status quantity at the time of estimation, said reference status being determined on the basis of a monitored value expressing the state of welding;
• means for correcting the welding conditions on the basis of the result of comparison;
• and
• means for modifying, during a welding operation, at least one of a configuration of said heat conduction simulator and a numerical value of said heat conduction simulator on the basis of the result of comparison so as to make said status quantity coincide with said reference status quantity.