Land vehicles: bodies and tops – Bodies – Body shell
Reexamination Certificate
1999-09-15
2001-05-08
Dayoan, D. Glenn (Department: 3612)
Land vehicles: bodies and tops
Bodies
Body shell
C296S146600, C052S749100
Reexamination Certificate
active
06227609
ABSTRACT:
FIELD OF INVENTION
This invention relates to vehicle door reinforcement and more particularly the formation of a reinforcing beam for a vehicle door.
BACKGROUND OF THE INVENTION
Reinforcing beams of the type herein contemplated are well known in the art. A typical commercially used beam is constructed of a piece of roll formed channel or flanged channel structure having separate end sections suitably fixed to opposite ends thereof. The fabricated structure is made of untempered steel and, after fabrication, the resultant beam structure is tempered in ovens to give it ultrahigh strength characteristics.
The requirement to separately fabricate at least three separate components and to then assemble the components materially contributes to the costs involved in producing the composite tempered beam. Another cost contributor is the need to heat temper the beams after fabrication.
There have been proposals in the patented literature to provide a beam with a one-piece construction. Examples are included in the disclosures of the following patents: U.S. Pat. No. 4,919,473 and Japanese Patent Publication No. 8-258569. The approach apparently taken in these designs is to achieve adequate strength by forming the beam with a steel having a strength something less than ultrahigh strength steel and compensating for the lesser material strength by constructing the beam with a special impact resistant cross-sectional configuration. Others have proposed utter simplicity in cross-sectional configuration and have provided the required strength by initially forming a composite laminar sheet. See, for example, U.S. Pat. No. 5,272,341.
The present invention is based upon gaining the necessary strength by utilizing ultrahigh strength steel as a starting material rather than achieving the desired strength after formation by heat tempering. Heat treating sheet steel while it is still in a roll or coil formation is more economical than heat treating individually fabricated structures even though the heat process is made as nearly “continuous” as possible.
The problem presented by utilizing ultrahigh strength steel as a starting material is that it is not easily cold formed into three dimensional configurations. Simple stamping operations often result in the creation of internal stresses which can distort portions of the formed sheet metal especially flat sections. There is a need to provide a reinforcing beam of the type discussed which can overcome the problems noted above.
BRIEF DESCRIPTION OF THE INVENTION
The disadvantages of the prior art may be overcome by providing a vehicle door reinforcing beam cut and cold formed from a flat sheet of ultrahigh strength steel comprising a beam blank cut from a flat sheet of ultrahigh strength steel to provide an elongated generally flat central blank portion extending from end to end of the beam blank and integral side blank portions on opposite sides of the central blank portion. The central blank portion includes opposite end wall sections constructed and arranged to be fixedly secured to the vehicle door frame and an elongated central wall section extending between the end wall sections. The side blank portions include leg wall sections integral with the sides of the central wall section and bent by cold forming in a direction away from a flat surface of the central wall section to form a central reinforcing channel structure having leg section free ends defined by the leg wall sections adjacent the end wall sections and central wall section ends integral with the end wall sections. The central blank portion has notches formed therein at positions outwardly of the leg section free ends so as to limit the occurrence of distortional stresses occasioned by the cold form bending of the side wall sections to those insufficient to distort the generally flat extent of the end wall sections with respect to the central wall section.
Preferably, the ultrahigh strength steel sheet from which the blank is cut is pretempered and flange wall sections are bent from the leg wall sections to provide a central reinforcing flanged channel structure.
According to another aspect of the invention, there is provided a method of making a vehicle door reinforcing beam including an elongated generally flat central blank portion and integral side blank portions on opposite sides of the central blank portion, in which the central blank portion including opposite end wall sections constructed and arranged to be fixedly secured to the vehicle door frame and an elongated central wall section extending between the end wall sections and the side blank portions include leg wall sections integral with the sides of the central wall section extending in a direction away from a flat surface of the central wall section to form a central reinforcing channel structure having leg section free ends defined by the leg wall sections adjacent the end wall sections and central wall section ends integral with the end wall sections. The method comprises cutting a beam blank from a flat sheet of ultrahigh strength steel with an outline defining the central and side blank portions and notches in the central blank portion at positions inwardly of the leg section free ends and bending the leg wall sections from the side of the central wall section in a cold forming operation in such a way that the notches limit the occurrence of distortional stresses to those insufficient to distort the generally flat extent of the end wall sections with respect to the central wall section.
REFERENCES:
patent: 4684166 (1987-08-01), Kanodia
patent: 4919473 (1990-04-01), Laimighofer et al.
patent: 5092512 (1992-03-01), Sturrus et al.
patent: 5104026 (1992-04-01), Sturrus et al.
patent: 5272841 (1993-12-01), Freeman et al.
patent: 5306058 (1994-04-01), Sturrus et al.
patent: 5370437 (1994-12-01), Alberda
patent: 5600931 (1997-02-01), Jonsson
patent: 5755167 (1998-05-01), Ciucani
patent: 5755484 (1998-05-01), Chou et al.
patent: 29622985 (1997-10-01), None
patent: 19715795 (1998-10-01), None
patent: 0728607A2 (1996-08-01), None
patent: 5286364 (1993-11-01), None
patent: 8-258569 (1996-10-01), None
patent: 9-220930 (1997-08-01), None
Cosma International Inc.
Dayoan D. Glenn
Engle Patricia L.
Pillsbury & Winthrop LLP
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