Heat-activated structural foam reinforced hydroform

A method for forming a reinforced hydroform for an automotive vehicle, comprising:

• providing an outer elongated metal tube having an open center;
• providing an elongated inner metal tube having an inner surface defining an open bore and an outer surface;
• applying an expandable material to the outer surface of the inner metal tube, the expandable material being substantially solid upon application;
• placing the inner metal tube within the open center of the outer elongated metal tube such that the expandable material is positioned between the inner surface of the inner tube and the outer surface of the outer tube;
• hydroforming the inner tube and the outer tube for forming a first hydroformed contour in the inner tube and a second hydroformed contour in the outer tube while at least a portion of the expandable material is located between the inner tube and the outer tube;
• and
• activating the expandable material to expand between the inner tube and the outer tube thereby forming a structural foam that adheres to at least one of the first hydroformed contour and the second hydroformed contour.

A method for forming a reinforced hydroform for an automotive vehicle, comprising:

• providing an outer elongated metal tube having an open center;
• providing an elongated inner metal tube having an inner surface defining an open bore and an outer surface;
• applying an expandable material to the outer surface of the inner metal tube, the expandable material being epoxy-based and substantially solid upon application;
• placing the inner metal tube within the open center of the outer elongated metal tube such that the expandable material is positioned between the inner surface of the inner tube and the outer surface of the outer tube and such that the inner tube is substantially concentric with the outer tube;
• hydroforming the inner tube and the outer tube simultaneously for forming a first hydroformed contour in the inner tube and a second hydroformed contour in the outer tube wherein;
• i) the first hydroformed contour is adjacent to and corresponding with the second hydroform contour and at least a portion of the expandable material is located between the first hydroformed contour and the second hydroformed;
• and
• heating the expandable material to expand the expandable material between the first hydroformed contour and the second hydroformed contour thereby forming a structural foam that adheres to the inner surface of the outer tube and to the outer surface of the inner tube wherein the structural foam extends along at least a portion of the length of the inner tube and further wherein the inner tube, the outer tube and the foam cooperatively form at least a portion of a frame of an automotive vehicle.

A method for forming a reinforced hydroform automotive vehicle frame structure, comprising:

• providing an outer tubular structure having an inner surface defining an open bore;
• providing an inner tubular structure having an outer surface;
• introducing a thermally activated polymeric material within a space defined between the inner surface of the outer tubular structure and the outer surface of the inner tubular structure;
• bonding the thermally activated polymeric material to at least one of the tubular structures;
• hydroforming the outer tubular structure and the inner tubular structure with the thermally activated polymeric material therebetween to form the automotive vehicle frame structure.