Receptacles – Cookware
Reexamination Certificate
2003-03-14
2004-09-21
Beck, Shrive P. (Department: 1762)
Receptacles
Cookware
C427S409000, C220S573200
Reexamination Certificate
active
06793093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an anti-stick cookware, more particularly to an anti-stick cookware which includes a relatively thick bottom portion as compared to a side portion thereof, and which has the characteristics of being heated evenly, relatively light, anti-stick and abrasion resistant.
2. Description of the Related Art
A conventional cookware is usually made of metal material, such as stainless steel or aluminum alloy. Aluminum alloy is preferred because of the lightweight characteristics thereof. The conventional processes for manufacturing cookware include gravity die-casting process, injection die-casting process and punching and drawing process.
The gravity die-casting process includes the steps of melting metal material, such as aluminum alloy, into a liquid molten metal, pouring the liquid molten metal into a casting die having the configuration of the cookware body, solidifying the liquid molten metal, and removing the cookware body from the casting die. The injection die-casting process includes the steps of melting the metal material into a liquid molten metal, pouring the liquid molten metal into an injection casting machine, injecting the liquid molten metal into a die having the configuration of the cookware body, solidifying the liquid molten metal, and removing the cookware body from the die. However, the aforesaid two processes encounter the drawbacks such as low productivity and high cost. The punching and drawing process includes the step of punching and drawing a metal plate for forming directly into a cookware body. Therefore, the punching and drawing process has relatively higher productivity and lower cost as compared to the gravity die-casting and injection die-casting processes and thus, is commonly used in the art.
However, the cookware produced from the punching and drawing process has bottom and side portions with identical thickness. If the bottom portion of the cookware is too thin, the cookware will be heated unevenly, and the anti-stick layer (such as fluorocarbon resin) coated on the cookware will be destroyed. On the other hand, if the bottom portion of the cookware is too thick, the overall weight of the cookware and the required material for the cookware are increased. Therefore, the cookware is not convenient to use and is not economical.
U.S. Pat. No. 2,941,289 discloses a process of making a clad metal cooking utensil from a clad metal blank including a layer of copper and a relatively thin layer of stainless steel bonded to the layer of copper. In the cooking utensil made thereby, the thickness of the side wall ranges from about 65% to about 100% of the thickness of the bottom wall. This patent does not suggest that the side wall of the cooking utensil be reduced to a thickness less than 65% of the thickness of the bottom wall.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide an anti-stick aluminum cookware which includes a relatively thin side portion as compared to a bottom portion thereof, and which is relatively light weight while still having sufficient strength.
Accordingly, the anti-stick cookware of this invention is manufactured by a process comprising the steps of:
spinning a metal plate, which is made of an aluminum alloy, to form a cookware body having a bottom portion, a side portion extending upward from the bottom portion, and an inner cooking surface defined by the bottom and side portions, the side portion of the cookware body having a thickness thinner than that of the bottom portion of the cookware body, wherein the thickness of the bottom portion of the cookware is at least 2.5 mm, the thickness of the side portion of the cookware is at least 1.8 mm, and the thickness of the side portion is 30%-64% of that of the bottom portion;
cleaning and roughening the inner cooking surface;
applying a metallic scratch-resistant layer onto the inner cooking surface, after being cleaned and roughened, by electric-arc spraying an abrasive metal onto the inner cooking surface; and
applying an anti-stick layer of fluorocarbon resin onto the scratch-resistant layer.
REFERENCES:
patent: 2941289 (1960-06-01), Chace
patent: 3983275 (1976-09-01), Winter et al.
patent: 4064726 (1977-12-01), Hinze
patent: 5411771 (1995-05-01), Tsai
patent: 5455102 (1995-10-01), Tsai
patent: 5462769 (1995-10-01), Tsai
patent: 5545439 (1996-08-01), Deng et al.
patent: 5753313 (1998-05-01), Tsai
patent: 5827573 (1998-10-01), Tsai
Beck Shrive P.
Fletcher, III William Phillip
Renner , Otto, Boisselle & Sklar, LLP
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