Method of manufacturing a tubular structural part, and tubular structural part
In a method of making a tubular structural part for a motor vehicle, a metal plate is contoured and preformed in at least one shaping step into a tubular body. Subsequently, the tubular body is end-formed into the structural part by internal high-pressure application while free contact regions snugly bear upon one another. The structural part is at least partially heated and quenched in a holding tool acted upon with a coolant.
1. A method of making a tubular structural part for a motor vehicle, comprising the steps in the order of:
trimming a metal plate about its circumference;
forming the metal plate into a tubular body with edge-side contact regions snugly bearing upon one another;
heating the tubular body to a temperature above the AC3 temperature point;
end-forming the tubular body into a structural part in the absence of any preceding joining process using internal high-pressure application in an internal high-pressure tool while the contact regions are tightly compressed upon one another during the internal high-pressure forming process by a pressing force acting upon the contact regions; and
cooling the tubular body in the tool during internal high-pressure forming process to thereby harden the tubular body.
2. The method of claim 1 , wherein the forming step includes shaping the metal plate into a U shape before transforming it into the tubular body.
3. The method of claim 1 , wherein the contact regions of the tubular body are formed on flange portions which flatly lie upon one another.
4. The method of claim 1 , further comprising providing end portions of the tubular body with at least substantially round cross section.
5. The method of claim 4 , wherein at least the end portions of the tubular body are each shaped by at least a mandrel.