Method for construction of vehicle space frame

Abstract

There is provided a remotely constructible, three dimensional space frame for a motor vehicle which comprises a plurality of elongated, metal structural members with outer surfaces and having axially uniform cross sections and a plurality of thin walled, interconnecting metal castings of at least first and second types. These metal castings each have (a) a saddle portion with a contour matching a portion of the cross section for one of the structural members and are laterally engageable with that one structure for axial movement of the casting along the structure and (b) a receptacle with an elongated tubular portion having a cross section matching the cross section of another structural member and intersecting with the saddle portion of the casting at a given angle so that the thin walled metal casting can be moved axially along one of the structural members and will receive a second structural member by movement of that second member into the casting. The two structural members are held with respect to each other at a given angle. The saddle portion and tubular portion of the many castings each have outer peripheral edges lying along the outer surface of the two structural members. A welded bead is deposited along these peripheral edges of the two casting portions and between the edges and the two structural members. In this fashion, the thin walled metal casing provides a variable junction for use with the structural members at a given joint necessary to construct the three dimensional space frame of a motor vehicle. The metal castings used in this space frame have a uniform wall thickness and are formed by a unique metal casting process wherein molten metal is drawn into a cavity of a rigid, self supporting, gas permeable low temperature bonded, sand grain mold by a vacuum applied through the sand mold while the mold is partially submerged in a bath of the molten metal.