A Three-Dimensional Joint Location Algorithm for Electron Beam Welding

Scanning with a low-power electron beam to locate joints is a widely accepted adaptive control technique. It has been most successfully used in those applications where fit-up and joint geometry are well-controlled, but precise beam positioning beyond the capability of optics systems is required. Deep penetration electron beam welding requires precise collinear alignment of the welding beam and the joint. A new software-based scanning algorithm takes into account the fact that conventional scanning only defines the top surface of the joint. The technique uses conventional scanning methods to locate the joint and collect information about the joint, calculates the axes positions required, then positions the beam and joint for the required collinear alignment before welding. Prior to this development, the only alternatives were painstaking manual alignment or high precision delicate fixturing. Both of these alternatives were inconsistent with the unskilled labor environment and the medium-to-high production heavy section weld shop environment.