Robotic Shielded Metal Arc Welding

In this work, the development and validation of a methodology for robotic welding with covered electrodes (SMAW) using a variation of the tool center point (TCP) model is shown. The covered electrode becomes part of the kinematic model of the robot as an additional prismatic joint, whose movement is determined by the electrode consumption or melting rate. This allows programming the trajectory to be welded similarly to welding processes with continuous wire feeding (GMAW or FCAW). In these processes, the points of beginning and end of each section of the trajectory are defined by the programmer and the robot performs, by default, the predefined trajectory of the TCP between these points, while the wire is fed independently of the robot movement. The robot performs feeding of the covered electrode through a diving movement while carrying out the advance movement along the trajectory. A closed loop mesh controls the length of the electric arc using the measurement of the voltage supplied by the welding machine. This compensates for the variation in the electrode voltage drop due to its length and temperature in order to maintain the arc length constant throughout the weld.