Patent Application
20050214560
The present invention relates to a stabilizer bar, and more particularly, the invention relates to reinforcing particular areas of a stabilizer bar.
Stabilizer bars are used in vehicle applications to provide lateral stability to a vehicle during turning maneuvers. The stabilizer bars are manufactured using a process that often results in concentration of stresses in locations along the stabilizer bar. The areas of the stabilizer bar having the stress concentrations are more susceptible to fatigue failure. As a result, prior art stabilizer bars may utilize a larger diameter along the entire length of the bar to provide sufficient thickness in typically weak areas of the bar. Using a larger diameter in areas other than those having the stress concentration results in a heavier bar than necessary, which adds weight and cost to the stabilizer bar.
Other prior art stabilizer bars attempt to provide additional strength in weak areas typically subject to fatigue failure by providing complex geometries or cross-sections that vary along the length of the stabilizer bar. While these stabilizer bar arrangements may be effective in improving the overall fatigue life of the stabilizer bar, the bar may be difficult to process due to the complex shape of the bar. In particular, it is difficult to achieve a stabilizer bar having complex geometries since stabilizer bars are typically constructed using solid bar stock having a uniform circular cross-section.
Therefore, what is needed is a stabilizer bar having areas typically subject to fatigue failure reinforced without increasing the size and weight of the bar in other areas of the stabilizer bar requiring less strength.
The inventive manufacturing process produces a stabilizer bar having a thickened, reinforced portion formed by thermal spraying a molten metal onto a surface of the bar. The inventive manufacturing process produces a stabilizer bar having a thickened portion in the areas typically subject to fatigue failure while avoiding the addition of unnecessary material and weight to other locations of the stabilizer bar not needing reinforcement. Furthermore, inexpensive bar stock having a circular cross-section may be used.
The step of thermal spraying the molten material onto the surface of the bar may be incorporated in any number of suitable points during the manufacturing process. In one example, the unprocessed bar stock may be thermally sprayed in desired locations. The thermally sprayed bar may then be formed into a desired shape and heat treated. The heat treated, formed, and sprayed bar may then be shot peened. Alternatively, the bar may be thermally sprayed after the surface has been prepared by shot peening. Forming of the bar may also occur before thermal spraying, and pretreated bar stock may also be used.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
The inventive stabilizer bar manufacturing process uses thermal spraying to produce a thickened portion of the bar providing increased strength and reinforcement in that portion as compared to other thinner portions of the bar. The inventive thermal spraying stabilizer bar manufacturing process effectively provides localized reinforcement of the bar without increasing the complexity of the manufacturing process or requiring expensive, specially shaped bar stock. The thermal spraying step may be incorporated at any number of suitable points in the stabilizer bar manufacturing process, however, the point at which the stabilizer bar is thermal sprayed is influenced by a number of considerations, which will be discussed in more detail below.
One example manufacturing process 10 is shown in
Returning to
The process of thermal spraying the bar, forming, and heat treating the bar, results in stress concentrations that would otherwise reduce the strength of the bar. The bar is shot peened as indicated at 32 by directing shot or balls 36 from an impeller or nozzle 34 at high velocity at the surface 22 of the bar. Shot peening plastically deforms the surface 38 imparting beneficial compressive residual stresses, which increases the strength of the bar.
Another inventive stabilizer bar manufacturing process is shown in
Still another inventive manufacturing process 44 is shown in
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
