Land vehicles: bodies and tops – Tops – Roof structure
Reexamination Certificate
1998-09-17
2001-06-12
Dayoan, D. Glenn (Department: 3612)
Land vehicles: bodies and tops
Tops
Roof structure
C296S216010, C296S216060, C296S201000, C296S096210, C296S901010, C052S309100, C052S309160
Reexamination Certificate
active
06244653
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to resin molded objects such as, for example, resin windows that can be used, for example, as a sunroof of a car, as well as methods and dies used for manufacturing such resin molded objects.
2. Description of the Related Art
Window units made of transparent resin materials that are lighter than glass have been used as sunroofs and other windows in various types of vehicles in order to replace similar glass units that are designed to allow light into the inside of the vehicle. Resin materials have been substituted for glass materials because functionally similar units are much lighter in weight and thereby allow the manufacturer to reduce the overall weight of the vehicle. Such resin windows typically have been manufactured using injection-molding techniques, and typically transparent synthesized resins, such as polycarbonate or acrylic resins, have been utilized.
However, known resin-molded windows have been subject to problems because the resin material does not provide sufficient rigidity against bending and twisting. Reduced rigidity in comparison to similar glass window units results because the elastic modulus of resin is lower than that of glass.
One known technique for overcoming this rigidity problem is to provide an integrally formed reinforcing rib
12
around the periphery of the window body on the inside surface of the window unit, as shown in
FIGS. 21 and 22
. When such a reinforcing rib
12
is formed, however, sink marks are known to appear on the surface of the window body
11
corresponding to the rib-formed portion, as a result of the injection molding manufacturing process used to fabricate such resin window units. Thus, when reinforcing the resin window unit to increase rigidity, another problem, namely the external appearance of the window is spoiled, is created. Consequently, when the total size of the window is large and/or when the external appearance of the window is a matter of great importance, such resin-molded objects can not be reinforced with such a rib
12
.
In addition, known resin window units have been designed with a reinforcing member
13
made of steel, aluminum, or the like. In such a case, the reinforcing member
13
effectively reinforces the window in conjunction with the rib
12
. However, this design increases the weight of the resin window unit and minimizes the reduced weight advantage that resin window units have over glass window units.
SUMMARY OF THE INVENTION
Therefore, it is one object of the present invention to overcome such problems with known window units.
Preferably, an improved resin molded object is constructed using two components. The first component is a main body. In preferred aspects of the present teachings, the main body is a window having a generally smooth surface and is generally transparent to light, although shading may optionally be provided. The first component has a portion for joining a second component, which second component preferably is a reinforcing piece. This reinforcing piece preferably protrudes from the molded body when the first and second component are assembled together in a manner that provides additional rigidity to the main body. The process for assembling the first and second components is preferably a two step injection molding process, although other assembly processes may be utilized.
Preferably, both components are constructed from a resin material, although any lightweight and generally transparent material will be appropriate. In addition, the first and second components may be constructed from the same or different materials. Further, the attaching structure for joining the two components into a single unit is not particularly limited as long as a reliable, secure fit is provided. Preferred attaching structure designs are described further below.
In a second aspect of the present teachings, the appearance of sink marks on the surface of the main body opposite of the protruded member formed surface can be prevented, because the main body can be fabricated independently of the protruded member. Therefore, resin material objects, and in particular resin window units, having an attractive external appearance can be prepared.
In a third aspect of the present teachings, the window unit preferably is constructed using a two step process. In the first step, either the first component, such as an object body, or the second component, such as a protruded member, is formed using a fixed die and a first movable die. In the second step, the component that was not formed in the first step is formed using the fixed die and a second movable die. Preferably, the component formed in the second step is molded within or around the other component so that the two components do not require any additional steps to assemble the first and second components. However, additional steps may be utilized in the fabrication and assembly process, if desired.
Further, dies that can be utilized to prepare resin window units are taught in a fourth aspect of the present teachings. Preferably, the dies include a fixed die, a first movable die and a second movable die. The first movable die has a first molding surface corresponding to one component of the resin molded object formed in the first step described above and the second movable die has a second molding surface corresponding to the other component formed in the second molding process. The first and second molding surfaces can be constructed to be as opposite sides of the same movable die, and each of these two molding surfaces will oppose the fixed die during each respective step of the molding process. This die design permits the manufacturing cost of the dies to be reduced over designs that utilize two separate movable dies, because the molding surface of the movable die can be rotated or flipped over to the other side with respect to the fixed die. Thus, a resin molded object can be formed in double molding using one molding machine. However, techniques for constructing improved resin molded objects using two separate movable dies are also taught.
Additional objects, features and advantages of the present invention will be understood by reviewing the detailed description of the invention and the claims in conjunction with the drawings.
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Combinmelt-Technologie fur Mehrfarben und Mehrkomponentenspritzguss, KGK Kautschuk Gummi Kunststoffe, vol. 49, 7-8/96, pp. 485-486.
Imaizumi Hiroyuki
Iwakiri Tsuneaki
Nishio Akiteru
Blankenship Greg
Dayoan D. Glenn
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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