| 摘要 |
A resistance spot welding apparatus having a primary circuit, a secondary circuit and a transformer for controlling the quality of a resistance spot weld, wherein a voltage is applied to the primary circuit to thereby generating a welding current, includes a current sensor for sensing the weld current from the primary circuit, a power factor calculator, a dynamic resistance calculator, a nugget estimator and a weld current controller. In the welding apparatus, the power factor calculator calculates power factors based on the welding current. And, the nugget estimator estimates a nugget size and nugget penetration from an dynamic resistance curve by using a Hidden Markov Model method, wherein the dynamic resistance curve is obtained by the power factor calculator. The quality of the resistance spot weld is controlled by changing the welding current based on the nugget size and the nugget penetration.
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