Method of making large volume hollow bodies

#Our present invention relates to a method of making large-volume-hollow bodies at least in part by hydrostatic deformation of a cold-formable metal. More particularly, the invention relates to the fabrication of bodies by hydrostatic shaping, especially for containers such as the fuel tanks of motor vehicles.

#The reference to large-volume hollow bodies herein is understood to refer to hollow bodies which may have a capacity of 10 liters or more and can be used, for example, for fuel tanks for automotive vehicles.

#In DE 44 36 436, a method of hydrostatic shaping of cold-formable sheet metal is described in which two planar sheets of the metal are fabricated by hydroforming into two matching halves of the large volume body and are then welded together along their equator line and peripherally to produce the hollow body.

#The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

#FIG. 1 is an elevational view of a flat blank which has been cut from a cold-deformable sheet metal to a shape matched to conformation of a frustoconical hollow body;

#FIG. 2 is a perspective view in diagrammatic form illustrating the tubular body or three-dimensional structure formed from that blank by welding the opposite edges thereof together;

#In the drawing the large volume hollow body as a whole has been indicated by the reference character 10. As can be seen from FIGS. 9 and 10, for example, that hollow body 10 can be somewhat tapered from a large diameter end to a smaller diameter end and can be generally a frustoconical configuration. It may be provided with inwardly-extending ribs 10a and 10b formed by pressing the body of the material outwardly in regions 10c, 10d and 10e on opposite sides of these ribs. The fuel tank can be formed with a hole shown only in dot dash lines at 10f surrounded by an outwardly-projecting collar 10g which subsequent to the hydrostatic pressing and to which the other tubular fitting for filling the tank may be welded.

#The hollow body 10 is fabricated from a cold working sheet blank 11 (FIG. 1) whose edges have been trimmed to converge so that this blank conforms to the developed configuration of the hollow body 10 prior to expansion and when rolled, yields a tubular body 12 (FIG. 2) with two open ends A1 and A2. The opposite edges of the body which converge in the blank are welded together to form a butt weld seam by tungsten inert gas welding. The laser beam welding can also be used to form the pressure-tight weld seam shown at S1 in FIG. 2.

#The tubular body 2 which corresponds to the three-dimensional structure mentioned previously can also be partly cylindrical or can have cylindrical portions.