Abstract: Disclosed is an automatic fillet weld tracing mechanism for two materials to be welded which are arranged stepwise and parallel to each other. A first motor driving mechanism is positioned at a fixed height and vertically reciprocates a first driven member having secured thereto a first sensor, said first sensor being positioned adjacent a first material to be welded with a given gap therebetween. A second driving mechanism is fixed to the first driven member and vertically reciprocates a second driven member to which is attached a second sensor held adjacent a second material to be welded with a given gap therebetween. The second driving mechanism also drives a third driving mechanism via a differential having a predetermined gear ratio. The third driving mechanism vertically reciprocates a third driven member having a welding torch attached thereto, the welding torch being positioned to weld at the gap between the materials.

Abstract: Herein disclosed is an automatic welding apparatus which comprises an arcuate frame including a welding unit and a pair of wire feeders, and an arcuate frame including a running truck and a pair of clamping mechanisms for fastening the outer circumference of a pipe to be welded. The aforementioned two arcuate frames are detachably connected at two positions thereby to form a ring shape. Thus, the pipe is automatically welded while the truck is being made to run in the circumferential direction. The running truck of the welding apparatus thus constructed carries both a mechanism for effecting close contact with the outer circumference of the pipe and a shock absorbing mechanism so that the distance between the leading end of a welding torch and the outer circumference of the pipe may be constant at all times.