Vehicle fenders – Buffer or bumper type – Composite bumper
Reexamination Certificate
2000-02-23
2001-09-11
Pape, Joseph D. (Department: 3612)
Vehicle fenders
Buffer or bumper type
Composite bumper
C293S102000, C293S132000
Reexamination Certificate
active
06286879
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to bumpers for automobiles and, more specifically, to an I-section bumper having improved impact performance and formed from mineral filled glass mat thermoplastic composites.
BACKGROUND OF THE INVENTION
By their nature, automobile bumpers must be able to withstand considerable impact. Metal or metal reinforced bumpers have heretofore been the only practical alternative for car makers because of the strength and durability associated with the metal components. Unfortunately, metal bumper components are expensive to produce, and add substantial weight to automobiles, decreasing fuel efficiency.
Car makers and automotive parts makers have experimented a great deal with plastic bumpers, seeking a cheaper and lighter weight substitute for the heavier traditional metal bumpers. Though appreciable progress has been made, plastic bumpers still have a strength to weight ratio that is unacceptable to the automotive industry. There are two aspects to the shortcomings of the plastic bumpers. First, the automotive industry has been unable to develop a plastic material that is economically viable with acceptable tensile and impact strength for bumper use. Second, the automotive industry has been unable a develop a plastic frame arrangement capable of withstanding impacts typically encountered in automobile accidents.
Currently, the most popular plastic materials used for automotive parts and bumpers are glass mat thermoplastics. Glass mat thermoplastic (GMT) composites are a family of compression-moldable, fiberglass-reinforced materials with thermoplastic matrices whose mechanical properties are generally higher than those of standard, injection-molded thermoplastic composites. GMT is available in the following glass-mat types: continuous-strand, randomly oriented glass-mat products which provide a good balance of stiffness and strength in all three axes; unidirectional long-glass-fiber mats which add directional stiffness and strength in a single axis; and, long, chopped fiber glass mats which provide improved flow properties and improvements in energy management with minimum decrease in stiffness.
The different glass mats are combined with a thermoplastic resin, usually polypropylene, (although other higher temperature engineering resins are also offered) to form a moldable product. GMT products are supplied in sheet or blank form to processors who shape the materials by compression molding or thermostamping.
Until recently, plastic bumpers have traditionally been manufactured with frame arrangements having a “C” or a “W” cross-section; the “C” or the “W” is used to describe the shape of the plastic cross-members connecting the front and rear plastic bumper walls. These configurations were chosen because of favorable energy absorption characteristics, especially when the bumper was impacted with a vertical component of force. I-section plastic bumper design has evolved over the past 10-years. Reinforced plastic bumpers have provided adequate performance and significant weight reduction but at a cost penalty. In 1992, the publication Plastic News speculated that “A new bumper design concept—the I-beam—offers the potential for making plastic bumper beams even lighter weight and cost competitive with steel bumpers up to volumes in excess of 100,000 per year.”
U.S. Pat. No. 5,269,574, to Bhutani et al. discloses a bumper with an I-beam shape constructed of fiber reinforced thermoplastic or thermoset reinforcing resin. The fiber reinforcing the thermoplastic is selected from a group of unoxidizable steel fibers, aluminized glass fibers, cellulosic fibers or glass fibers. Unfortunately, implementation of the design disclosed by Bhutani et al. presents molding problems that are inconsistent with the economic constraints in the automobile industry. For example, the Bhutani et al. I-section bumper structure having ribbed sections fails to form adequately during molding. X-ray analysis shows that only 50 to 80% of the fibers used in the molding of the Bhutani et al. bumper flow into the ribs. The economic considerations require that mounting stays be integral to the structure.
SUMMARY OF INVENTION
The invention is an I-section bumper formed from fiber reinforced thermoplastic wherein the fiber additions consist of a long, chopped glass mat with the addition of mineral fillers such as mica, talc or clay. The use of mineral fillers allows for the replacement of more costly fibers. The invented reinforced thermoplastic material has favorable flow characteristics which enable the material to substantially fill the deep ribs and mounting stay structures used in I-section bumpers during compression molding while improving the modulus or cross-face stiffness of a finished part. For the first time, improved flow characteristics during molding permit the material to flow evenly into small ribs, bosses and other features. This makes it possible to increase part integration, molding pencil braces, fascia supports, mounting holes and mounting stays. The first surface is covered with a conformal energy absorber made of plastic foam. Moreover, the absorber serves to mount an appearance fascia. The result is a cost-reduced, weight-reduced bumper with improved impact resistance. The invented bumper is economical, light weight and exhibits superior performance in comparison with steel-based bumpers in safety and deformation resistance upon impact.
OBJECT OF THE INVENTION
The principal object of this invention is to provide an I-section bumper for automobiles that is formed from plastic material.
Another, more particular object of this invention is to provide a GMT bumper for automobiles that satisfies all relevant requirements for structural integrity under standardized impact tests, while significantly reducing manufacturing cost and part weight.
Another object of this invention is to provide a GMT bumper for automobiles that has favorable flow characteristics during compression molding of the bumper.
REFERENCES:
patent: 4098943 (1978-07-01), Degginger et al.
patent: 5269574 (1993-12-01), Bhutani et al.
patent: 5804511 (1998-09-01), Kelman et al.
patent: 5883021 (1999-03-01), Beer et al.
patent: 5910458 (1999-06-01), Beer et al.
patent: 5914163 (1999-06-01), Browne
patent: 5985429 (1999-06-01), Plummer et al.
patent: 6099055 (2000-08-01), Hirota et al.
Bassett Walt
Haque Enamul
Lewis Thomas F.
Azdel, Inc.
Dougherty & Clements LLP
Pape Joseph D.
LandOfFree
I-Section automotive bumper formed from mineral-filled glass... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with I-Section automotive bumper formed from mineral-filled glass..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and I-Section automotive bumper formed from mineral-filled glass... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2514568