Position regulation of a charge carrier beam

Abstract

In a charge carrier beam machine, as an electron beam welding machine, a system for establishing the relative position of a beam impingement spot on a workpiece surface and a machine reference position, as a beam gun axis, comprises an X-ray sensor defining at least one measuring field boundary intersecting the workpiece surface at a line of intersection spaced from the gun axis. During repetitive measuring periods, the beam is deflected from the normal working position along a measuring path, which crosses the line of intersection, and a signal functionally related to the period of time the beam needs to travel from a reference position along the measuring path to the line of intersection is produced. This signal comprises the desired information about the relative position and can be used in a regulating apparatus for maintaining a desired relationship. Two sensors having differently oriented measuring field boundaries can be used to detect any deviations of the workpiece surface from a desired plane and the output signals of these detectors are useful for maintaining a desired positional relationship between a welding site and a filler wire supplied to the welding site. The shape of the cross-section of the beam may be altered during the measuring period to improve the accuracy of the measurement.