question

If you're trying to use a robot as an operator during a processor's process time (to simulate the idea of a welder) There's an answer here on the forums that covers that perfectly:

"Can a robot be used as a processor (or be connected to a processor as an operator)?"

If you'd like the animations or visual appearance of the robot to look more like a welding robot you can right click on the robot and under Edit > Animations, you can adjust the look and appearance of the robot, and animate it using keyframes. You can hide certain parts (like the clamp) to also make it look more like a welder.