Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Starting material is nonhollow planar finite length preform...
Reexamination Certificate
1999-11-30
2003-10-07
Lee, Edmund H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Starting material is nonhollow planar finite length preform...
C264S238000, C264S295000, C264S296000, C264S322000, C029S428000
Reexamination Certificate
active
06630097
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for constructing a plastic door for a household electrical appliance, and in particular a method for constructing a plastic door for a refrigerator and the refrigerator door obtained in this manner.
2. Description of the Related Art
As is well known, each refrigerator door, for example of a multi-compartment upright refrigerator, comprises a shell or outer part with which a door liner is associated. Usual insulating material is provided between the two parts. The door liner can comprise support shoulders for shelves to hold foods and food containers. A usual seal element is provided along the liner edge.
The door shell and, liner are produced by usual forming methods such as vacuum-forming or by pressing (moulding). After they have been formed they are joined together and insulating material such as polyurethane is inserted (injected) between them. The shell also supports usual junction pieces carrying the hinges or comprising seats for these latter.
The known method for producing a plastic door for a refrigerator generally results in a door being obtained having sharp edges. The joints between the shell and liner can often be seen along these edges. This obviously has a negative effect on the appearance of the product.
U.S. Pat. No. 5716581 describes a method for thermoforming a plastic refrigerator door of the aforesaid type. According to this known method a shell is formed with an annular flange facing the shell interior to receive the edge of a liner. In this respect, after the door liner has been thermoformed, a plastic sheet is laid on it and is itself thermoformed to form the shell. As soon as this has been completed the shell and liner are fitted together and heat is applied along their contacting edges to join them together by fusion of the parts. After the shell and liner have been joined together their end edges are cut off. This thus implies a final product which always has sharp edged lateral parts, and in which the shell and liner edges are recognizable. Consequently, the invention of this U.S. patent again results in a product which is not of perfect appearance.
SUMMARY OF THE INVENTION
An object of the invention is to provide an improved method for producing a thermoformed plastic door, by which the door is of attractive appearance.
A further object is to provide a method of the aforesaid type which is of reliable implementation and offers a product of constant results.
A further object is to provide a door produced by the aforesaid method which is of attractive appearance and does not present junction lines between the shell and liner along its lateral edges.
A further object is to provide a method which enables refrigerator doors to be produced which do not have to be subjected to final painting and which therefore enables doors to be obtained at lower cost than the doors produced by known methods.
In accord with the above objects, the present invention is directed to a method for constructing a door for a refrigerator. The door being of plastic and comprising a shell or outer part with which an inner door liner is associated and wherein the shell is formed by known forming methods such as vacuum-forming or pressing. Following the following step, the edge of said shell is deformed and bent towards the interior of this latter, the bending being implemented along the entire perimetrical edge of the shell. The process further includes the step of maintaining the shell within the forming mould when the perimetrical edge is bent. Alternatively, the shell may be transferred to another mould wherein the perimetrical edges are bent.
REFERENCES:
patent: 2837816 (1958-06-01), Saunders
patent: 2976577 (1961-03-01), Gould
patent: 3000058 (1961-09-01), Thielen, Jr.
patent: 3634971 (1972-01-01), Kesling
patent: 3637971 (1972-01-01), Kesling
patent: 3770546 (1973-11-01), Childress et al.
patent: 3882637 (1975-05-01), Lindenschmidt
patent: 4896415 (1990-01-01), Bock
patent: 5624623 (1997-04-01), Luch et al.
patent: 5716581 (1998-02-01), Tirrell et al.
patent: 6492000 (2002-12-01), Matsuki et al.
patent: 6508973 (2003-01-01), Beckmann et al.
Maritan Marco
Signa Marco
Colligan John F.
Krefman Stephen
Lee Edmund H.
Rice Robert O.
Whirlpool Corporation
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