SOLDAGEM ROBOTIZADA COM ELETRODO REVESTIDO UTILIZANDO CONTROLE DE COMPRIMENTO DO ARCO ELÉTRICO COM COMPENSAÇÃO DA TEMPERATURA DO ELETRODO

The objective of this work is to show the results obtained with the shielded metal arc welding (SMAW) using an anthropomorphic robot. The procedure allies the robotization benefits such as quality, repeatability, traceability and flexibility to the ones inherent of the SMAW process, such as the chemical composition and microstructure control by using different electrodes and coatings. The diving movement must be done into the weld pool, maintaining the arc length constant, independently of the translation speed. To determine the arc length, the welding voltage and the electrode temperature are monitored, in order to compensate the melting rate and the material electric resistivity increase. It is observed that, controlling only the voltage, although the robot is able to keep it constant, the arc length significantly increases at the end of the weld bead, because the voltage drop on the electrode diminishes during electrode consumption. To compensate this effect, the voltage drop is modeled considering the electrode length reduction and the electric resistivity increase with the temperature. It is possible to keep the arc length constant during the entire welding.