Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Controlling heat transfer with molding material
Reexamination Certificate
1997-10-27
2001-11-20
Kuhns, Allan R. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Controlling heat transfer with molding material
C264S046400, C264S046600, C264S255000, C264S268000
Reexamination Certificate
active
06319436
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention pertains to the art of closure devices and methods for making closure devices and, more particularly, to such devices and their manufacture used in covering and sealing openings or apertures formed in thin plates, rigid sheets of metal, or other materials.
The invention is particularly applicable to the type of closure plugs used for covering openings in motor vehicle body panels and will be described with particular reference thereto. It is to be appreciated, however, that the invention has broader applications and may advantageously be employed for other uses in a variety of different environments whenever it is necessary to cover and seal an opening in a support panel.
In the manufacture of motor vehicles, closure devices are used to permanently close various body panel apertures or access openings which have served their intended purpose and are no longer required, or to perform some other useful function such as to reduce the effective diameter of an opening to a desired new size or to provide a suitable mounting surface for another component. Such openings may be required initially for many reasons, e.g., as paint discharge openings or access openings to accommodate mounting of vehicle components. It is typically required that these discharge or access apertures be tightly covered and sealed after they have served their useful function in order to prevent moisture, road dirt, noise, exhaust fumes, and the like from entering into the motor vehicle through the panel aperture.
Conventional closure devices that provide a fluid-tight seal have heretofore included a main body portion attached to a separate sealing ring made from a material different than that comprising the body of the closure device. The main body portion of the conventional closure devices are typically formed of a durable metal material or a resilient synthetic or plastic material to ensure the mechanical integrity of the closure device. The sealing rings, however, are often formed from soft materials such as extruded rubberized compounds or heat sealable materials. During the manufacture of such conventional closure devices, much time and effort is consumed in first extruding and die cutting the sealing rings and then in mounting the separate sealing rings onto the body of the closure devices such as by a mechanical connection, or by using adhesives or the like. Often, the sealing rings are attached to the plug bodies by hand. Such arrangement and practice is disadvantageous because of the additional cost and labor investment required.
Two-shot molding techniques have been used in the past to mold various components from two different materials. As an example, two-shot molding can be used to form parts having two different colors or to form parts having two different hardness regions. However, two-shot molding techniques have heretofore been unsuccessful in producing parts formed of a rigid plastic together with a thermoexpandable material due mainly to an inability to control the temperature of the molding dies.
It has, therefore, been considered desirable to develop a new and improved closure device and assembly and method for making same which overcomes the foregoing deficiencies and others while providing better and more effective operation of results.
BRIEF SUMMARY OF THE INVENTION
According to the subject invention, a closure assembly is provided for use in covering and sealing an aperture formed in a support panel. The assembly includes a thin cover cap having a flat top and an underside provided with a plurality of axially extending, circumferentially spaced apart, resilient guide elements and a corresponding plurality of axially extending circumferentially spaced apart retaining legs. The guide elements and retaining legs cooperate to form a locating shoulder on the underside so that the closure assembly can be snap-locked into position in an opening. The closure assembly is provided with a heat responsive thermoexpandable annular plastic ring that is carried on a corresponding circular wall formed on the underside of the cover cap. When the closure assembly is in place in an aperture and subjected to heat in the range of 85° C. to 180° C., the thermoexpandable annular plastic ring undergoes a transformation whereat the ring expands to occupy a space of about 1.5 times its original size. The expanding annular plastic ring flows in all directions between the underside of the cover cap and the vehicle body panel to form a fluid-type seal between the plug and the panel.
According to another aspect of the invention, a closure assembly having the above described construction is manufactured using a two-shot injection molding process. During the first shot, the cover cap is formed together with the guide elements and retaining legs by injecting a resilient nylon material into the mold cavity. During a second period, the mold cavity is cooled and adapted to receive the secondary material forming the annular seal ring. During a third period, the secondary thermoexpandable material is injected into the mold to form the annular seal ring on the cover cap. The unitary closure assembly is ejected from the injection molding machine after the third period.
The principal advantage of the present invention is in the improved method for assembling a unitary closure assembly formed of dissimilar compounds.
Another advantage of the present invention is in the improved method of operating a two-shot injection molding machine for constructing a unitary closure assembly formed of dissimilar compounds.
Still another advantage of the present invention is in an improved beryllium copper molding die for use in a two-shot injection molding machine to construct a unitary closure assembly formed of dissimilar compounds.
Yet another advantage of the present invention is the provision of an improved closure assembly for covering and sealing an aperture in a panel manufactured through the two-shot molding process of the type generally above.
Another advantage of the invention resides in the provision of such an assembly which can serve as a protective guard and securely close a panel aperture.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.
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European Search Report dated Nov. 30, 1999.
Gordon Gary G.
Jaeger Wilfred R.
Fay Sharpe Fagan Minnich & McKee LLP
Kuhns Allan R.
TRW Inc.
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