Metal deforming – By use of roller or roller-like tool-element – With modification or control of temperature of work – tool or...
Reexamination Certificate
1998-12-17
2001-01-30
Butler, Rodney A. (Department: 3725)
Metal deforming
By use of roller or roller-like tool-element
With modification or control of temperature of work, tool or...
C072S201000
Reexamination Certificate
active
06178798
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an impact beam for a door of an automotive vehicle and, more particularly, to a method and apparatus for making a heat treated side intrusion beam.
To improve safety in motor vehicles, side intrusion beams, also called side impact beams, have been designed into the passenger doors of automotive vehicles. Side intrusion beams are typically formed of steel or combinations of steel and composite materials. The side intrusion beams extend across the vehicle doors to provide occupant protection. Typically, the side intrusion beams have a beam body with a pair of brackets mounted at each end. The brackets are used to mount the beam body within the door. Commonly, side intrusion beam manufacturers provide the beam body and bracket assembly to the automotive vehicle manufacturer for installation as the doors are being assembled.
Federal motor vehicle safety standards require that side intrusion beams meet certain load or energy absorbing criteria for a specified lateral displacement of the door in response to a vehicle being subjected to a side impact. Reducing the cost of implementing the federal safety standards is an ever present goal of automotive vehicle manufacturers. Many previously known side intrusion beam assemblies require the use of relatively expensive materials and expensive material processing due to the high strength requirements.
Several examples of side intrusion beams use abeam body which is formed of heat treated steel. The beam body is subjected to heat-treating throughout the length of the beam. The beam is then welded to the end brackets that are not heat treated. Commonly, long lengths of heat treated steel material is provided to the manufacturer of the side intrusion beam. The beam body is cut to length and then welded to the end brackets. One problem with such a method for forming side intrusion beams is that purchasing already hardened steel is extremely expensive. Also, because the material is so hard, special processing techniques such as laser cutting must be implemented to properly size the beam bodies. Special processing techniques use special equipment that is relatively expensive. Another drawback to such prior beams is that because the brackets are not hardened and the entire steel bar is hardened, more stress is placed on the welds. That is, the entire beam resists bending while the brackets deform. Thus, the impact is directed to the weld area where the weld material absorbs much of the energy of impact, rather than the beam and brackets.
SUMMARY OF INVENTION
It is therefore an object of the invention to provide improved load absorbing characteristics for a side intrusion beam while reducing the cost to manufacture such beams.
In one aspect, the present invention provides a side intrusion beam assembly having a pair of end brackets and a beam body coupled thereto. The beam body has a length with a center portion and end portions. The end portions are mounted to the bracket. The center portion of the beam is heat treated while the end portions are not.
In a further aspect, the present invention provides a method of forming a side intrusion beam comprising the steps of: moving beam stock through a heater; controlling the heater to cycle between an on-state and an off-state with respect to predetermined portions of the length of the beam; quenching the beam stock; and, cutting the beam stock at the untreated portions to form the beam.
In yet another aspect an apparatus for forming a side intrusion beam has a plurality of rollers for moving beam stock along a predetermined path, the beam stock has a length. A heater is mounted adjacent to the predetermined path. A quenching apparatus is also mounted adjacent to the path after the heater. A controller is coupled to the heater for controlling the operation between an on-state and an off-state with respect to the length of the beam stock to form heat treated portions and non heated portions respectively.
One advantage of the present invention is that a less expensive cutting process may be used to cut the beam stock because the cuts are made at the non heat treated portions. The result is a more cost efficient method for cutting the beams.
Another advantage of the present invention is that the end portions of the beam body are not heat treated and thus conditions are more favorable for stronger welds between the non heat treated metal of the brackets and the beam body. Welding is easier and more reliable when joining two similar hardness materials.
Yet another advantage of the present invention is that distortion in the beam body is reduced. That is, as a beam stock is heat treated, the beam stock warps as a function of length. Because the amount of heat-treatment is reduced, less distortion will occur.
Still another advantage is that improved bending characteristics are obtained because the bracket and non heat treated portion of the beam become flaccid during crash.
REFERENCES:
patent: 4781054 (1988-11-01), Brown et al.
patent: 5272896 (1993-12-01), Mine
Kowalski Ben
Kowalski Daniel J.
Rowady Edward
Butler Rodney A.
Dykema Gossett PLLC
Trim Trends, Inc.
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