Automatic Riveting in Aeroplane Construction: With Descriptions of Two Machines Developed in Germany

THE heat‐hardened, so‐called “strong,” aluminium alloys such as Avional and Duralumin, require a special technique in making joints. In the common aircraft steels permanent joints are usually made by welding, but this method is only applicable to hardened aluminium alloys to a limited extent, since the unavoidable heating of the joint may destroy the strength of the material—whether produced by annealing at 500 deg., quenching in cold water, and subsequent ageing at room temperature, or by artificial “ageing” at a temperature of about 150 deg. for several hours. Such loss of strength being usually undesirable, riveting must in the majority of cases be substituted for welding; although in recent practice spot welding has come into use, particularly for thin material up to about 1–5 mm. In that case, the heating is only quite local and of short duration, and the resulting loss of strength inconsiderable.