ALL-STEEL welded bodies for passenger-cars have many advantages over composite bodies, among them being fewer parts, doors of only two pieces, no visible outside seams, lower tops for the same headroom, less roof weight, lower center of gravity, greater safety, increased visibility, permanent quiet, economical upkeep and perfect outside lines. Wood and steel react so differently to stress that neither adds much to the strength of the other in a composite structure. Steel alone, welded into a unit structure, is lighter and less bulky. The entire side of the body is stamped from a single sheet, with the openings die formed to reenforce it. Chassis frame and body follow the same lines, so that they reenforce each other and body sills can be omitted. This plan saves 2 in. in height, as compared with some other bodies.
Flash welding is employed to join sheets 120 in. long and of any desired width, because mills are not equipped to produce, economically and speedily, sheets of the required accuracy. The tonneau rear seams are flash welded also, and the cowl and roof are attached by spot welding. Flash welding of the larger sheets requires uncommonly accurate alignment of the edges of the metal due to the scarfing operation which trims both sides of the weld in one operation. Magnetic clamping allows perfect alignment since the pressure is self-contained. Handling the large units for welding small reenforcements like those for hinges, locks and fender bolts can only be accomplished on a spot-welding machine of great flexibility, used in conjunction with overhead carrying equipment. Electrodes are important; most of them are of hard-drawn copper or a material that contains a large percentage of copper. To secure long life, electrodes are cooled to within ½ in. of their points wherever possible.
The automobile body really is a container designed for transportation purposes. It must have a certain capacity, must be strong and serviceable, must possess certain conveniences and must meet the requirements of appearance. In the all-steel body, the necessary skin or shell is utilized as the chief structural member and reenforced by additional strengthening members wherever needed. In a sedan are found 2303 spot welds and 140 in. of flash welding, plus the welding of the open sheets.
Various applications of welding and the different methods are covered in the discussion, special emphasis being laid on the ductility of the metal in the weld. The welding of thin sheet metal is also considered. Relative tensile strengths of the weld and the parent metal are mentioned, as well as the point at which a weld ruptures. In this connection one member suggests testing the parent metal before welding and comparing the results with those obtained from the welded piece to show the effect of welding upon the metal.
