Land vehicles: bodies and tops – Bodies – Structural detail
Reexamination Certificate
2000-12-08
2001-09-25
Pape, Joseph D. (Department: 3612)
Land vehicles: bodies and tops
Bodies
Structural detail
C296S203020, C180S068400
Reexamination Certificate
active
06293615
ABSTRACT:
TECHNICAL FIELD
The present invention relates to injection molding an integrated front end reinforcement for a vehicle.
BACKGROUND ART
Many components are assembled to the front end of a vehicle that require precise alignment and durable mounting mechanisms. Headlights, parking lights, a decorative grill and a radiator are parts that may be attached directly or indirectly to a grill opening reinforcement. Grill opening reinforcements have been found to be helpful in tying together such components with the forward section of front fenders and the frame of a vehicle as it is being assembled.
Other integrated front end modules that support other parts include bumper reinforcements, radiator supports, and inner fender reinforcements. These parts are relatively large and must maintain close tolerances for critical dimensions to meet strict fit and finish standards.
Grill opening reinforcements and other integrated front end modules have traditionally been manufactured from a plurality of sheet metal stampings that are either welded or fastened together. Metal integrated front end modules are heavy and add to the overall vehicle weight. Being formed in multiple pieces, metal integrated front end modules require labor intensive assembly operations. Quality control is required to assure proper location of the mounting mechanisms for multiple parts assembled to the integrated front end module.
Recently, sheet molding compound (SMC) has been used to manufacture grill opening reinforcements. SMC grill opening reinforcements are generally slightly less weight than metal grill opening reinforcements. SMC grill opening reinforcements require a substantial investment in tooling for both molding the SMC and finishing the SMC parts after molding. It is generally necessary to machine a SMC grill opening reinforcement by drilling, punching or shaping with a router fastener holes and locating surfaces. Also, the SMC process is relatively slow requiring a large number of mold cavities to manufacture parts on a production basis. SMC is also not a recyclable material which means that at the end of the car's life cycle or if there is any scrap in manufacturing process, it is necessary to dispose of the SMC grill opening reinforcement in landfill instead of recycling.
It is believed that prior art attempts have been made to injection mold structural parts for vehicles. In normal vehicle assembly operations, vehicle subassemblies are subject to electro-coating at temperatures in excess of 450° F. and after painting vehicle subassemblies are cycled through paint drying ovens where they are exposed to temperatures in excess of 200° F. Prior attempts to utilize injection molded thermoplastic parts that are attached to automobile vehicle bodies prior to electro-coating and paint drying oven exposure have been unsuccessful when attempted with large parts such as grill opening reinforcements and other large integrated modules. Exposure of large weight bearing parts to high temperatures results in a loss of dimensional stability since the weight of parts attached to injection molded parts causes the injection molded parts to sag. This results in poor fit and finish and difficulties in assembling components after being exposed to high temperatures.
These and other disadvantages and problems encountered by the prior art are addressed by the present invention as summarized below.
DISCLOSURE OF INVENTION
According to the present invention, a method of making an integrated front end reinforcement module is disclosed. The injection molded front end reinforcement panel includes integrally molded fastener bosses, fastener receptacles and integrally molded reinforcement ribs that are formed of a fiber reinforced thermoplastic polymer. A partially assembled vehicle body is provided that has partially unattached body panels secured to a frame. The integrated front end module is secured to the frame. Unattached body panels are attached to the integrated front end module. Brackets are secured to the integrated front end module. The above assembly is referred to as a basic vehicle front end assembly and does not include subsequently assembled of light receptacles, bumper trim, and the decorative grill. The basic vehicle front end assembly is then immersed in an electrco-coat bath that is heated to more than 450° F. The basic vehicle front end assembly is then painted and baked in paint ovens at a temperature of more than 200° F. Subsequently, the light receptacles, lights, bumper trim, and grill are secured to the respective brackets and mounting surfaces.
According to another aspect of the present invention, a grill opening reinforcement is molded in one piece and extends transversely across the entire width of the front end assembly from a right front fender to a left front fender. During the molding step, the fastener bosses are formed with core cylinders provided in an injected molded die that eliminates post-forming machining operations such as drilling, punching and shaping with a router.
According to another aspect of the present invention, the fiber reinforced thermoplastic polymer used includes at least 65% post-consumer recycled polyethylene terephthalate. The polyethylene terephthalate is reinforced with at least 45% glass fibers and mineral filled.
According to another aspect of the invention, a vehicle front end assembly is provided. The vehicle front end assembly includes a frame and an injection molded front end module is secured to the frame to extend transversely across the vehicle at the front end thereof. The integrated front end module has a plurality of fastener bosses integrally molded as a part of the front end module and a plurality of reinforcement ribs integrally molded as part of the front end module. A plurality of unpainted body panels are secured to the fastener bosses of the front end module. A plurality of brackets could be secured to the fastener bosses of the front end module. Alternatively, ribs or flanges provided on the reinforcement can be directly secured to the body. The frame, injection molded front end module, body panels and brackets are assembled together to form a vehicle body/frame pre-assembly and are subsequently immersed in a hot dipped electro-coating bath.
According to another aspect of the invention, the vehicle body/frame pre-assembly further comprises a paint coating applied thereto that is baked in an oven.
The front end modular reinforcement panel is formed from a glass fiber/mineral filled thermoplastic polymer. The thermoplastic polymer is preferably polyethylene terephthalate.
The method of making a vehicle front end assembly and front end pre-assembly offers advantages in that cost savings may be achieved through labor and tooling cost reduction that more than offset the increased cost of the fiber filled thermoplastic polymer compound. Improved fit and finish possible with the method can enhance overall product quality.
Another advantage of the invention is that a grill opening reinforcement has dimensional stability even after heating in the electro-coat immersion bath and paint ovens.
Substantial weight savings are possible depending in part on the design of the one piece grill opening reinforcement.
The use of thermoplastic polymer formed by injection molding reduces or eliminates machining that was formerly required of SMC grill opening reinforcement panels that required drilling, punching and shaping with router tools. According to the present invention, the injection molded thermoplastic material may be made to net size and shape with fastener bosses being integrally molded.
The thermoplastic polymer is easily recyclable. Further, parts such as grill opening reinforcements that are injection molded from a thermoplastic polymer are easier to manufacture and have less scrap when compared to SMC front end modules that may crack, resulting in the creation of scrap.
These and other objects and advantages of the present invention are better understood in view of the attached drawings and in light of the following detailed description of the invention.
REF
Brooks & Kushman P.C.
Pape Joseph D.
Patent Holding Company
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