Abstract: A method of producing a seal ring for a floating seal assembly comprising forming a seal ring base from a low carbon steel, the seal ring base having a sealing portion formed thereon, subjecting the sealing portion to shot blasting, plasma spraying a cermet material on the sealing portion of the seal ring base to form a coated layer of the cermet material thereon, and lapping the coated layer to obtain a finished seal ring product having a plasma sprayed and lapped coating of the cermet material on the sealing portion.

Abstract: A welding method in which a pair of base metals are welded together by swinging the welding torch right and left, and a device for practicing the method. In the method, the arc current is continuously detected, and sampling pulses are formed in time slots provided by the swinging motion of the torch. The arc welding currents are sampled and held with the aid of the sampling pulses, whereby the peak values of arc currents flowing when the torch is swung right and left are detected, and the position of the torch is correctively shifted right or left according to the difference between these peak values.

Abstract: In a method of detecting a weld line, the positions of the weld line and the welding wire are detected from the video signal of the weld, which is provided by an industrial television camera. The video signal of the weld is compared with a predetermined threshold so as to be binary-coded into a signal representing a dark part and a signal representing a bright part. Clock signals having a predetermined frequency are counted with the binary-coded signals as gating signals, thereby to count the lengths of the dark part and the bright parts. The count values are subjected to difference processing, so that the positions of the weld line and the welding wire are detected from the maximum values of the results of the difference processing.