Vehicle fenders – Buffer or bumper type
Reexamination Certificate
1996-08-19
2001-12-04
Gordon, Stephen T. (Department: 3612)
Vehicle fenders
Buffer or bumper type
C293S120000
Reexamination Certificate
active
06325430
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to motor vehicle truck parts and particularly to a back bumper.
BACKGROUND
Chrome-plated steel and aluminum bumpers have been available for heavy weight trucks for a number of years to enhance the appearance of the truck. However, as soon as a fastener is inserted through the chrome-plated steel or aluminum bumper and tightened to secure the bumper to the truck body, the brittle, thin chrome plating is fractured, and the corrosion process immediately starts. It is then simply a matter of time before the corrosion appears, thus ruining the visual appearance and effect of the shiny chrome. As the corrosion process continues, the chrome plating separates from the base metal, further distracting from the appearance of the bumper. Further corrosion also affects the structural integrity of the bumper. Eventually, the truck owner replaces the unsightly and structurally weakened bumper, and the corrosion process repeats itself as soon as the fasteners are tightened.
One attempt to solve the problem has been to weld threaded studs to the back surface of the bumper. These welded studs replace the use of fasteners that are inserted through the bumper to secure it to the truck body. These threaded studs are typically spot welded to the bumper, which provides minimal attachment force. Spot welds easily fracture when the bumper and, particularly a heavy weight truck bumper, is subjected to an impact or the constant vibration of the truck. A larger surface weld or fillet can be applied to the rear surface of the bumper and the threaded stud with the result that the structural integrity of the stud is weakened due to the heat. Furthermore, this larger weld also heats a larger area of the chrome-plated bumper and for a longer period of time. This can result in the chrome-plating being compromised in the heated area. Separation of the chrome plating from the base metal occurs, and the corrosion process is again enhanced.
Fasteners or apertures placed through any bumper visually distract from the uniform shiny appearance of the exterior bumper surface. The fasteners or aperture edges also reflect light at different angles than the bumper surface, thereby creating a safety concern for oncoming traffic.
A chrome-plated plastic layer has also been utilized, but even the most minor impact fractures the brittle chrome plating as well as the plastic layer.
Stainless steel has been utilized for truck bumpers, but any thickness sufficient for structural integrity is limited to a dull or not very bright surface. Furthermore, any fasteners placed through the stainless steel plate also distract from the visual appearance thereof
Stainless steel has also been utilized for other truck parts such as fenders, which have been chrome-plated. However, the stainless steel utilized in these chrome-plated parts is 430 series stainless steel, which is high in chromium and susceptible to oxidation. As a result, as soon as the chrome plating is fractured or compromised, the base stainless steel metal oxidizes with the corrosion appearing through the fracture or compromised area.
SUMMARY OF THE INVENTION
The foregoing problems are solved and a technical advance is achieved in an illustrative truck bumper utilizing a laminated construction and having an outer sheet with an exterior surface having a prescribed mechanical finish such as preferably a bright or highly reflective finish for significantly enhancing the appearance thereof. The laminated construction of the bumper also includes a reinforcing sheet that is configured into a generally U-shaped channel and disposed in the channel recess of the similarly configured channel of the outer sheet. The exterior surface of the outer sheet can advantageously be free of apertures or fastener components, which distract from the uniform visual appearance of the outer sheet and can reflect light in an undesired and unsafe manner to oncoming vehicles. This laminated construction also permits the use of highly reflective or mirror-like finishes that are only commercially and economically available with thinner gauge materials such as stainless steel. The uniform appearance of a highly reflective finish on the outer sheet is advantageously obtained by the use of indentations or projections formed in the reinforcing sheet in which a fastener is positioned therein and extends therefrom into the channel recesses of the outer and reinforcing sheets. The head of the fastener is also fixedly secured to the reinforcing sheet in the indentation and minimizes, if not eliminates, breakage therefrom as with threaded studs that are merely spot welded thereto or severely weakened when welded thereto. The laminated construction thus provides a lightweight bumper that is physically sound and has an exterior surface exhibiting the desired mechanical finish. This laminated construction also permits the use of materials that are resistant to corrosion and preserve the highly desired mechanical finish for extended periods of time.
In one aspect, the mechanical finish is a bright or bright annealed finish such as an AISI, No. 2B, 2BA, 4, 7, or 8 finish. In the preferred embodiment, the outer sheet comprises stainless steel, and the mechanical finish is a reflective finish such as an American Iron and Steel Institute (AISI), No. 2B, 2BA, 3, 4, 7, or 8 finish. The laminated construction of the truck bumper facilitates the use of limited thickness material such as 14 gauge stainless steel with a highly reflective or mirror-like finish such as the No. 7 or 8 American Iron and Steel Institute (AISI) mechanical finish. The finish can be further protected with a transparent coating of, for example, polyvinylchloride. As a result, stainless steel having a thickness of no more than 14 gauge or 0.075 inches with a reflective or highly reflective finish is advantageously available for use in the laminated, truck bumper.
As previously suggested, the fastener of this laminated truck bumper includes a head that is disposed in a reinforcing sheet indentation below the exterior surface surrounding the indentation. This also permits fixedly positioning the head such as welding the fastener head in the indentation. To further secure the bumper to the truck without breaking the integrity of the exterior outer sheet surface, a standoff is disposed on a leg of the generally U-shaped outer sheet channel.
The integrity of the exterior surface of the outer sheet is further maintained with closed ends. Stiffening members are disposed in the channel recesses to reinforce the closed ends. Scuff plates are also disposed across the recessed channels near the closed ends and directly in front of the truck tires to minimize the possibility of cutting or rupturing the tire when impacting the bumper.
To facilitate securing a tow cable to the truck, concentric apertures are formed in the outer and reinforcing sheets to allow placement of the cable therethrough. Concentric apertures can also be utilized for placement of a light fixture therein. A plurality of concentric fastener apertures can also be formed in the sheets should such be desired.
In another aspect, the laminated bumper with a highly reflective finish can be constructed with a plurality of concentric apertures extending therethrough. A light fixture can advantageously be positioned in selected concentric apertures. The outer sheet is thus formed from stainless steel having a 14 gauge maximum thickness and an exterior surface with a highly reflective or bright annealed finish.
In still another aspect of the invention, series 304 stainless steel is utilized because of its high nickel content, which distinguishes it from high chromium, series 430 stainless steel. The high nickel content, series 304 stainless steel is very resistant to oxidation and is essentially corrosion free. As a result, series 304 stainless steel has particular application in medical devices and, more particularly, implantable medical devices. A highly reflective finished piece of series 304 stainless steel can be chrome-plated to take on the appearance
Gordon Stephen T.
Morrow Jason
Varnum Riddering Schmidt Howlett LLP
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