Metal fusion bonding – Process – Using dynamic frictional energy
Reexamination Certificate
2000-09-22
2003-09-16
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Using dynamic frictional energy
C228S160000
Reexamination Certificate
active
06619533
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to automotive component parts. More specifically, the present invention relates to the efficient fabrication of automotive suspension parts by first extruding portions thereof, and subsequently joining these various sections to form the completed automotive parts.
2. Description of the Related Art
In any given automobile design, countless diverse components are operatively coupled together to create a sophisticated, high performance machine. Certain components are relatively simple in their design, but can always be improved. Further, the way these parts are fabricated can similarly be improved to provide additional advantages and features. For example, design improvements can continually be made to improve the structural integrity of the product itself. These design improvements may involve how internal component stresses can be better handled, or may allow for manufacturing efficiencies to be improved. Furthermore, weight reduction can be realized through these design improvements.
Many components have fairly straight forward design criteria based upon their purpose, function, and relationship with other components. One such component is the link arm, or link rod, that is used in suspension systems. A common link rod design is made up of a steel tube that is welded between a pair of steel eyes. Each eye is fabricated from a steel ring having a wall thickness sufficient to provide the necessary structural performance. To join these components together, the eyes are welded to each end of the steel tube. Generally a gas metal arc weld (GMAW) is utilized to achieve the necessary bonding characteristics.
As is obvious, any components, such as the link rod, which carry loads in a vehicle must easily withstand all loads without the possibility of failure. Due to the shape, design and interconnection of the various components that make up a typical link arm, a majority of the load stress is concentrated at the weld area. It is normally undesirable to have significant loads carried by welded joints due to the possibility of irregularities and inconsistencies in the weld. Geometrical changes are produced at weld joints which cause stress concentration areas reducing product performance. Significant changes in the geometry and metallurgy at the welded joints create a possibility for product breakage or failure. The location of weld joints is consequently a very important design consideration.
The use of designs which include a significant number of welded components are further undesirable due to problems in maintaining tolerances. More specifically, it is difficult to maintain precise tolerances among components when undergoing welding operations due to the substantial heat and material stresses that are introduced through the welding process, causing expansion, bending, bowing and other misalignment concerns. In the specific case of the link arm, maintaining exact dimensions and alignment between the two eyes becomes difficult during the welding processes.
Another consideration in today's market is that vehicles are becoming increasingly modular, which requires flexibility among the various components. Naturally, the various components must meet certain physical requirements which are dictated by their application. For example, the link arm is limited to certain lengths and overall dimensions which must possess sufficient structural integrity to withstand certain predetermined axial load levels. Various vehicles may require similar characteristics from its link arms, but may have different length specifications and packaging constraints. Unfortunately, two separately fabricated parts are typically necessary to meet this need.
In addition to all of the structural and strength requirements, weight and cost are also concerns. Any reduction in weight of various component parts results in similar weight reductions for the overall vehicle weight. Naturally, this will result in improved vehicle operating costs, power requirements, etc. Cost concerns are overcome by manufacturing efficiencies which help to reduce overall production costs, and final component part costs as well. Consequently, cost and weight reductions are continual goals when designing any particular component. Therefore, there exists a need to provide an improved link arm meeting the predetermined structural requirements while meeting or exceeding current efficiencies in cost and production, while allowing for a reduction in weight.
SUMMARY OF THE INVENTION
The present invention seeks to produce a link arm with a flexible design for use in a vehicle suspension system which has a need for a reduction in weight. Specifically, the present invention reduces the overall weight and manufacturing complexity of the link arm or rod while maintaining a competitive cost. In achieving these weight and cost savings, the design of the present invention provides either equal or improved levels of structural reliability.
To achieve the weight reduction desired, the link arm of the present invention is comprised entirely of aluminum (or other similar light weight materials). In the case of the extruded aluminum link rod of this present invention, weight reductions of thirty percent or more from a similarly sized and shaped traditional steel link arm can be realized. However, replacing steel with aluminum creates additional complications. That is, it is generally not practical to join a tubular aluminum rod to a pair of aluminum rings or eyes as was the approach in the steel link arm. This impracticality is due to differing material strengths and weld characteristics, with the welds having less than half of the strength of the base material. As previously discussed, the transition from the small diameter steel tube to the large diameter eye concentrates a majority of the load stress in the weld area. Aluminum components of this configuration would not easily meet all of the necessary manufacturing and design requirements of the end product while producing a weight reduction.
To achieve the desired weight reduction by utilizing aluminum, the configuration of the link arm of the present invention is quite distinct from its steel counterparts. Furthermore, to produce such an aluminum link arm in a cost effective manner, a new manufacturing process is utilized.
When viewed from the top (or bottom), the completed aluminum link arm has a generally rectangular configuration. When viewed from the side, a substantial portion of the interior or center section is also rectangular in configuration. Towards each end of the link arm, a transition area begins to taper outward and split, forming a pair of transition arms. An area between the transition arms is hollow. The transition arms terminate in an integrally connected hollow aluminum eye. Again, the entire link arm is fabricated from aluminum achieving a significant reduction in weight. As previously mentioned, other lightweight materials could also be used to fabricate the product, so long as they meet the material and performance requirements outlined below.
To form the aluminum link arm, aluminum is fed through an extrusion press to form components having the desired cross-sectional shape. Several options exist as to the exact number of extruded components required to form a completed link arm. While theoretically possible to form the entire link arm in a single extrusion process, this approach is not practical due to the length of a typical link rod. At present, it is not cost effective to utilize an extruder capable of producing a single extrusion link arm due to the higher cost and poor tolerances of larger extrusions. Thus, for practical purposes the aluminum link arm of the present invention is formed from at least two extruded components.
In a first embodiment, the extruded component forms one-half of the completed aluminum link arm. As further outlined below, these extruded components are then friction stir welded and subsequently cut to size after welding. The welded extrusion assembly has a length muc
Gall Mike
Hinrichs John F.
Hootman Jon
Noruk Jeffrey S.
Ruehl Phillip C.
Dunn Tom
Stoner Kiley
Tower Automotive Technology Products, Inc.
LandOfFree
Multi-piece extruded link arm does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-piece extruded link arm, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-piece extruded link arm will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3054790