Abstract: A method for monitoring a curved solidified weld seam during the welding of a workpiece includes carrying out distance measurements using a measurement beam of an optical coherence tomograph both at one or more pre-measurement points situated upstream of a present welding position, and at one or more post-measurement points situated downstream of the present welding position, and monitoring the curved, solidified weld seam on the basis of the distance measurements. In the case of a plurality of post-measurement points, a post-measurement line is formed from the plurality of post-measurement points and positioned to be offset relative to a pre-measurement line in the direction of the pre-measurement line toward the curved, solidified weld seam and/or is rotated relative to the pre-measurement line. In the case of a single post-measurement point, spacing the single post-measurement point from a line passing through the present welding position in the welding direction.

Abstract: A safety nut comprises an axial extension in which an elastic safety element is disposed. In one embodiment the element comprises a wire spring clip whose legs are tangent to a central thread of the nut so that a bolt threaded onto the nut flexes the legs and creates a reactive clamping force. In another embodiment the elastic element comprises a spring disk having a thread which is axially offset at only a portion relative to the nut thread. A bolt tends to axial distort the disk and thereby creates an axial reactive force which clamps the bolt. During manufacture, the disk is threaded simultaneously with the threading of the nut and is thereafter deformed at at least one location to create the axial offset relationship between the threads.