Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
2000-03-03
2002-02-12
Dunn, Tom (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
C219S06000A, C219S060200, C029S897200, C296S029000
Reexamination Certificate
active
06346684
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally related to welding operations and more particularly to a welding material assembly and method for using the same.
BACKGROUND OF THE INVENTION
Welding operations are used in many industrial applications, such as vehicle construction on vehicle assembly lines. To form a welded connection, a desired amount of the welding material must be placed between the surfaces of the weldable members where the joint is to be formed and then heated. This type of joint is difficult to form when the weldable members are tubular in form because it becomes difficult to directly access the surfaces to be welded.
Tubular hydroforming technology is increasingly being used in industry, particularly in the automotive industry. Hydroforming technology offers many advantages for automobile frame construction, but difficulties in welding hydroformed components arise due to the tubular shape of the parts. There is a need in the automotive industry for a technology that allows rapid, low cost joint formation between tubular hydroformed members.
SUMMARY OF THE INVENTION
To meet the needs identified above, the present invention provides a method of welding tubular hydroformed members comprising (a) hydroforming first and second tubular metal blanks to form respective first and second tubular members, each member being constructed of a first metallic material and each having an exterior surface portion; (b) providing at least one welding material member carried in a predetermined arrangement by a flexible carrier sheet, each welding material member being constructed of an electrically conductive metallic welding material capable of bonding in weld-forming relation with the first metallic material and having a greater electrical resistance and a lower melting point than the first metallic material, the flexible carrier sheet being made of an electrically nonconductive material; (c) positioning the first and second tubular hydroformed members and the carrier sheet so that the welding material members are each disposed in current-transmitting relation between the exterior surface portions of the first and second tubular hydroformed members to be joined together; and (d) applying an electrical current and forces across the first and second tubular hydroformed members such that the applied current flows through the surface portions and each welding material member disposed therebetween so as to melt each welding material member and thereby weld the exterior surfaces portions to one another.
Another objective of the present invention is to provide a welding material assembly for positioning a welding material in electrically conductive relation between exterior surface portions of first and second weldable members at a location where the first and second weldable members are to be joined. The welding material assembly includes at least one welding material member mounted on a flexible carrier sheet in a predetermined arrangement, each welding material member being constructed of an electrically conductive metallic welding material capable of melting when heated by application of an electrical current. Each carrier sheet is constructed of a material that is electrically nonconductive and each welding material member is mounted on the sheet such that when the sheet is placed between the exterior surfaces of the first and second weldable members to be welded, each welding material member is electrically conductively disposed therebetween.
The individual carrier sheets can be detachably joined together to form a rollable continuous strip to provide easy handling of the individual welding material assemblies. Accordingly, it is a further objective of the present invention to provide a rolled welding material strip assembly comprising a plurality of welding material assemblies. Each welding material assembly is constructed and arranged to position welding material in electrically conductive relation between exterior surface portions of first and second weldable members at a location where the first and second weldable members are to be joined together. Each assembly includes at least one welding material member mounted on a flexible carrier sheet. Each welding material member is constructed of an electrically conductive metallic welding material capable of melting when heated by application of an electrical current. Each carrier sheet is constructed of a material that is electrically nonconductive and each welding material member is mounted on the sheet such that when the sheet is placed between the exterior surfaces of the first and second weldable members to be welded, each welding material member is electrically conductively disposed therebetween. The welding material assemblies are removably secured to one another and form a rolled continuous strip of the sheets.
The welding material assemblies are particularly well suited to forming joints between individual weldable tubular hydroformed members when constructing a vehicle space frame. A method for forming a space frame for a motor vehicle is contemplated comprising (a) forming each of a pair of upper longitudinal members and a cross member in a hydroforming procedure. Each hydroforming procedure includes: (i) providing a tubular blank constructed of a first metallic material; (ii) placing the blank into a die assembly having die surfaces defining a die cavity; (iii) providing pressurized fluid in an interior of the blank to expand the metallic wall of the blank into conformity with the die surfaces thereby forming a tubular hydroformed weldable member. Each upper longitudinal member includes a pillar forming portion and a longitudinally extending portion. The cross member has a pair of leg portions and a cross section extending therebetween. The leg portions extend from junctures at opposite ends of the cross portion. Each longitudinally extending portion and each juncture has an exterior surface portion. (b) providing a pair of side rail structures; (c) providing a pair of welding material assemblies, each assembly comprising at least one welding material member carried in a predetermined arrangement by a flexible carrier sheet. Each welding material member is constructed of an electrically conductive metallic welding material capable of bonding in welding-forming relation with the first metallic material and has a greater electrical resistance and a lower melting point than the first metallic material. The flexible carrier sheet is made of an electrically nonconductive material; (d) assembling the side rail structures with the members, such that (i) the pillar forming portion of each upper longitudinal member is connected to and forms a pillar structure on a respective one of the side rail structures, (ii) each leg portion of the cross member is connected to a respective one of the side rail structures, and (iii) the surface portion of each upper longitudinal member and the surface portion of the associated juncture of the cross member are in adjacent relation to one another and an associated one of the welding material assemblies is positioned therebetween so that each welding material member is disposed in current transmitting relation between the associated exterior surface portions to be welded together; and (e) applying an electrical current and forces across the tubular hydroformed weldable members such that the applied current flows through the associated pair of exterior surface portions and through each welding material member disposed therebetween so as to melt each welding material member and thereby weld the exterior surface portions to one other.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.
REFERENCES:
patent: 1581931 (1926-04-01), Lamplugh
patent: 1846567 (1932-02-01), Murray, Jr.
patent: 2269451 (1942-01-01), Ford
patent: 2389907 (1945-11-01), Helmuth
patent: 2668722 (1954-02-01), Muller
patent: 3122629 (1964-02-01), Manz
patent: 3159419 (1964-12-01), Kerby
Gabbianelli Gianfranco
Miller Ralph
Cosma International Inc.
Dunn Tom
Edmondson L.
Pillsbury & Winthrop LLP
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