position control for electron beam welder - uses X=rays emitted during special measurement interval by beam travelling closed path intersecting weld direction

摘要

The welding process is punctuated by brief measurement intervals in which the electron beam (14) is deflected and made to trace out a closed path (22) spanning the seam (12) being welded (18,20). The beam interacts with the workpiece (10) and causes X-rays (28a) to be emitted from its surface. These X-rays are detected by X-ray detectors and the result used to control the position of the electron beams. The X-ray detector's output is a function of that length of any one section of the closed path travelled by the beam that lies between a reference position and the X-ray detector's aperture limit intersecting the closed path. The detector's aperture limit (i.e. area of measurement limit) is parallel to the feed direction (X). The associated measurement area lies on the side of the measurement area limit facing the processing zone. The detector's output is proportional to the distance between a reference axis (electron gun's axis) and the point where the closed path intersects the measurement area limit.