GB1309772A - Method of and device for inspecting and or controlling electron beam welded joints - Google Patents

Abstract

1309772 Testing welded joints electrically K H STEIGERWALD 1 May 1970 [6 May 1969] 21021/70 Headings G1N and G1A [Also in Divisions B3 and H4] In electron-beam welding a joint between workpieces, the values of a parameter occurring in the area of the joint being produced are measured during the welding process to give an indication of the joint quality. IN ONE EMBODIMENT temperature-sensitive elements are disposed about the joint, and measurements therefrom are used as an indication of the quality of the joint and to exert a control function on the apparatus effecting the weld. The measurements can be compared, for this purpose, with known optimum values. Should the welding energy diverge from the joint at any point along its length or depth Figs. 1-14, (not shown), a temperature gradient will exist between some of the detector elements on opposite sides of the joint. A number of arrangements of detector elements are described: they can be arranged both externally and internally of the workpieces, or on the upper and/or lower surfaces; the elements can be arranged to be stationary relative to the workpieces, or to move therealong during welding Fig. 20, (not shown). IN A PRACTICAL CONSTRUCTION (Fig. 21), the workpieces, 2, 4 are supported on apparatus which corrects the position of the joint relative to the electron-beam 78, in response to measurements from banks of detectors E11-E15, E21-E25, E31-E35, E41-E45, arranged on both sides of the joint along both workpiece surfaces. The workpieces can be tilted about axis 90 (which lies along the joint upper part), by motor M2, shifted axially by motor M1 and shifted laterally by motor M3. The apparatus includes amplifiers V1-V8 whose responses are used to control the various motors. In instances where the measurements relayed by these amplifiers are compared with previously-obtained optimum condition measurements, a programme generator comprising feelers and cam discs supply amplifiers V11-V14 is used to provide error signals which can be used to control the motors or reject workpieces. IN A MODIFICATION (Fig. 22) an infra-red image system 138 projects an image 2', 4' of the workpieces 2, 4 in the evacuated chamber 136 of the electron-beam welding device, on to image screen 142. The brightness of an image point corresponds to the temperature of the associated workpiece point. Photo-electric cells are moved along the image screen, giving indications of the workpiece temperature distribution as welding progresses. IN A FURTHER EMBODIMENT (Fig. 25) a signal generator 260 producing an alternating magnetic field, and hence circulating currents in the workpieces, is used. Detectors 262-268 can be stationary or moved during welding. The magnetic field distribution can be obtained and displayed on an oscilloscope by using an additional detector which sweeps transversely of the joint.