A KITCHEN UTENSIL WITH A TRIPLE BOTTOM AND PROCESS FOR MANUFACTURE THEREOF

Abstract: A kitchen utensil (1) with a triple bottom having recesses (3a) and reliefs (3b), and process for manufacture thereof, in which an aluminum plate (2) and a stainless plate (3) are jointed on the bottom (1a) of the utensil (1) by means of a friction press machine or a radio heating device, and the stainless plate (3) forming said bottom is engraved to have recesses (3a) of a certain shape thereon, in order to improve the joint between plates and to greatly increase the heat absorption and heat conductivity of utensil.

Description: D E S C R I P T I O N TITLE OF INVENTION A KITCHEN UTENSIL WITH A TRIPLE BOTTOM AND PROCESS FOR MANUFACTURE THEREOF BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a kitchen utensil with a triple bottom, in which an aluminum plate and a stainless plate are jointed on the bottom of utensil by means of a friction press machine or a radio heating device. More particularly, the present invention relates to a kitchen utensil with a triple bottom, in which a stainless plate forming said bottom is engraved to have recesses of a certain shape thereon, in order to improve the joint between plates and to greatly increase the heat absorption and heat conductivity of the utensil. The present invention also relates to a process for manufacturing the above-mentioned kitchen utensil. DESCRIPTION OF THE PRIOR ART Previously, there was a proposition of such kitchen utensil wherein an aluminum plate is jointed on the bottom of stainless utensil in order to increase the heat conduc¬ tivity of said utensil. A stainless plate is also jointed on the aluminum plate, in order to prevent the corrosion and damage of said aluminum plate. In conventional kitchen utensils as above-mentioned, however, the outwardly exposed lower surface of stainless bottom is shaped into a simple plane. The jointed area between the " stainless bottom and the aluminum plate is limited to the inner part of the utensil bottom except for the peripheral bottom edge formed between the cylindrical side wall and the bottom of utensil. Accordingly, the utensil has a single layer peripheral bottom edge. Therefore, such conventional kitchen utensil has insufficient heat absorption, in view of the fact that flames applied to the utensil bottom pass the circumferen¬ tial edge of said flat bottom just after heating said bottom and then outwardly disperse. As a result, there is the disadvantage of the considerable waste and loss of heat in such construction of kitchen utensil. Furthermore, there is a problem that the food contained in the utensil gets partly scorched or burned, because flames outwardly passing along the utensil bottom are applied concentratedly to the single layer peripheral bottom edge. Previously, various types of jointing methods have been proposed for simultaneously jointing an aluminum plate and a stainless plate to the bottom of stainless utensil. Among them, the method utilizing an instantaneous pressure of such device as a friction press and the method of radio heating which uses the powder type flux have been generally used in view of the saving of manufacture cost. Even with such methods utilizing the friction press and the radio heater, however, there are problems of increasing the manufacture cost and lowering the production rate, in view of the fact that excessive pressure or unnecessarily high heat may be required due to an unskilled operator. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the above-mentioned disadvantages countered in constructions of the prior art and , to provide a kitchen utensil with a triple bottom having recesses and reliefs wherein uniform heating is effected throughout the bottom of utensil including the peripheral bottom edge thereof, thereby causing the heat absorption of utensil to greatly increase. Another object of the present invention is to provide a method for manufacturing a kitchen utensil with a triple bottom having recesses and reliefs, said method enabling an improvement in the joint between members to be jointed together under minimum pressing and heating conditions. In accordance with an aspect, the present invention provides a kitchen utensil comprising a triple bottom jointing an aluminum plate and a stainless plate thereto, said utensil being characterized in that the joint portion between said plate is engraved to form recesses of a certain shape at the outwardly exposed lower surface of said stain- less plate, adjacent recesses being arranged to have a certain space therebetween, and that the up-curved peripheral edges of said plate are upwardly extended or curved to the upper end of up-curved bottom edge of said utensil to envelop said bottom edge. In accordance with the other aspect, the present inven¬ tion provides a method for manufacturing a kitchen utensil with a triple bottom, in which an aluminum plate and a stainless plate are jointed together to the bottom of said utensil by pressing the upper die against the lower die, said method being characterized by the step of; heating the bottom of said utensil placed on the lower die of conven¬ tional construction at a temperature of 300 to 500°C, said bottom carrying said aluminum plate thereon prior to the heating thereof; disposing said stainless plate on the upper surface of said aluminum plate; and pressing the upper die against the lower die under the pressure of about 400 to 600 kg/cm by using such device as a friction press in order to joint said plates together to the bottom of utensil, said upper die having a cavity being so-shaped as to upwardly extend or curve the peripheral edges if said plates to envelop the up-turned bottom edge of utensil and provided at the inner surface thereof with reliefs so shaped as to form the corresponding recesses on the joint portion between said plates. in accordance with another aspect, the present invention provides a method for manufacturing a kitchen utensil with a triple bottom, in which an aluminum plate and a stainless plate are jointed together to the bottom of said utensil by using a radio heating device, said method being characterized by the steps cf: disposing said aluminum plate and stainless plate on the lower surface of said bottom of utensil previously carried on the lower die of said radio heating device, said plates each being previously provided at the joint portion therebetween with the recesses and the up-curved peripheral edge by using a pressing method; applying a powder type flux to the jointing surfaces between said members to be jointed together; and jointing said members together in a manner of radio heating. BRIEF DESCRIPTION OF THE INVENTION FIG. 1 is a sectional view of a kitchen utensil in accordance with an embodiment of the present invention; FIG. 2 is a bottom view of a kitchen utensil shown in FIG. 1; FIG. 3 is an explanation showing one practicing example of the method of the present invention; FIG. 4 is 'a sectional view showing the jointing condition carried out- by the method shown in FIG. 3; FIG. 5 is an explanation showing the other practicing example of the method of the present invention; and FIGS. 6a, 6b, 6c, 6d, and 6e are bottom views showing different examples of a bottom of the utensil manufactured in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a kitchen utensil manufac¬ tured in accordance with an embodiment of the present inven¬ tion and FIG. 2 is a bottom view of said kitchen utensil, showing the bottom of the utensil. As shown in these draw¬ ings, an aluminum plate 2 and a stainless plate 3 are jointed together to the bottom la of the stainless kitchen utensil. In accordance with the present invention, the joint portion between the aluminum plate 2 and the stainless plate 3 is engraved to form recesses 3a of a certain shape on the out- wardly exposed lower surface of the stainless plate 3. Adjacent recesses 3a are arranged to have a certain space defining a relief 3b therebetween. Said aluminum plate 2 and stainless plate 3 have the up-curved peripheral edges 2c and 3c corresponding to the up-curved peripheral edge lc formed between the side wall lb and the bottom la of the utensil 1, respectively. The curved peripheral edges 2c and 3c upwardly extends to the upper end of the curved peripheral bottom edge lc, in order to envelop said bottom edge. In view of the fact that recesses 3a and reliefs 3b are formed at the bottom of the utensil 1, that is, the lower surface of the stainless plate 3, the area of heat conduc¬ tivity can be greatly increased at the bottom of the utensil. When a flame is applied to the bottom of the utensil, in order to heat 'the contents in said utensil, the staying time of flame at the bottom of utensil extends because the flames directly contacting with said recesses 3a and reliefs 3b pass them in turn along the utensil bottom and then out¬ wardly disperse from the utensil. As a result, the heat absorption of the utensil can be greatly improved. Furthermore, a uniform heating can be accomplished through¬ out the bottom of the utensil, so that the heating efficiency per time of the utensil of the present invention is greatly increased, as compared with the conventional utensil having a flat bottom. And also, there is no problem that the food contained in the utensil will get partly scorched or burned, since the up-curved bottom edge of the utensil to which flames are concentratedly applied is surrounded by the up- curved peripheral edges 2c and 3c of respective plates 2 and FIGS. 6a, 6b, 6c, 6d, and 6e show different examples of recesses and reliefs formed on the utensil bottom, that is, the stainless plate 3. By referring to these drawings, it can be understood that various shapes of the recesses 3a and the reliefs 3b may be employed and that their effects are similar to that of the example shown in FIG. 1. As the lower plate provided with the recesses and reliefs thereon, a copper plate or a brass plate may be used in place of the stainless plate 3, in order to more increase the heat conductivity. In manufacturing the above-mentioned construction of utensil, the method utilizing an instantaneous pressure of such device as a friction press or the method of radio heating which uses the powder type flux, may be preferably used in accordance with the present invention. Now, the method of the present invention will be described in detail. FIG. 3 shows an embodiment of the present invention wherein a friction press is used. The friction press includes a lower die 11 carrying the initially formed stain- less utensil 1 thereon and a upper die 12 having a cavity 12' and being pressed against said lower die 11 to joint the aluminum 'plate 2 and the stainless plate 3 to the bottom la of the utensil 1. The cavity 12' is provided at the inner surface thereof with a plurality of reliefs 12a having a certain shape and length. Adjacent reliefs are arranged to have a certain space defining a recess 12b. The cavity 12' has an up-curved peripheral edge with a sufficient depth to fully envelop the curved bottom edge of the utensil carried on the lower die 11. For the jointing operation, the alumium plate 2 is placed on the joint area of the bottom la of the utensil firmly carried on the lower die 11, and subjected to a heating at a temperature of about 300 to 500°C. Then, a stainless plate 3 is placed on the surface of said aluminum [late 2. Thereafter, the triple bottom of utensil is sub- jocted t.o a pressure of about 400 to 600 kg/cm by using the ' upper die 12 associated with a pressing device of the friction press. Thus, a utensil with a triple bottom having recesses and reliefs is manufactured. In accordance with the method of the present invention as above-mentioned, the pressure of the upper die 12 at the initial of the pressing step is not applied at the same time to all surfaces of the stainless plate, but applied to the surfaces contacting with respective front end of the reliefs. Thereby, the stainless plate and the aluminum plate are instantaneously deformed at said contacting areas. The structural change in the materials of plates due to the above-mentioned deformation results in a plastic deformation phenomenon that the materials expanded by the above-mentioned deformation are forcibly pushed into a recess 12b defined between adjacent reliefs 12a. Thus, a firm joint between the stainless plate 3 and the aluminum plate 2 is instan¬ taneously formed. The aluminum plate 2 expands towards the peripheral edge thereof between the bottom la of the utensil 1 and the outer stainless plate 3 by the instant pressure acting during the jointing operation. At this time, the peripheral edge of the aluminum plate 2 is curved by the curved peripheral edge 12c of the upper die 12 extending to the upper end of the peripheral bottom edge lc of the utensil 1, such that the aluminum plate 2 has a curved peripheral edge 2c corresponding to said peripheral bottom edge lc of the utensil. Accordingly, it is possible to prevent the bottom edge lc of the utensil 1 to be exposed outwardly. Because the edges of plates are uniformly jointed together, the finish treatment for improving the appearance of utensil can be completed by simple grinding and rinsing works, with- out the necessity of a cutting work. In accordance with the method of the present invention, the-applied pressure can be considerably lowered, as compared 2 with a high pressure (about 800 kg/cm ) required in the conventional jointing method utilizing the upper die for forming simple plane. The present invention also enables th<:- joint among the members 1 , 2, and 3 to be greatly improved even under the minimum heating condition of the aluminum plate. On the other hand, FIG. 5 shows another embodiment of the method of the present invention utilizing a radio heating method. The initially shaped stainless kitchen utensil 1' is carried on the base 21 of well-known radio heating device. In this case, the members jointed to the bottom l'a of the utensil 1, that is, the aluminum plate 2' and the stainless plate 3' are previously pressed to form at their bottoms the recesses 2'a and 3'a, and the reliefs 2'b and 3'b, as well as the curved edges 2'c and 3'c, respec¬ tively. Then, these plates 2' and 3' are disposed on the bottom l'a of the utensil 1. During the disposing operation, a powder type flux is applied to each joint surface between adjacent members to be jointed together. The joint between said members can be accomplished by a heating head 22. The bottom of the utensil 1' manufactured in a manner as above- mentioned has an effect identical to that of the bottom of the utensil 1 manufactured by using a friction press. . The test results of the kitchen utensil according to the present invention and the conventional kitchen utensil are indicated in the following table. Each utensil has a bottom diameter of 160mm. The tests were implemented for the samples which were rapidly cooled after being heated at a temperature of 450°C for 10 minutes. As can be found by referring to the above table, when heating respective contents of the above-noted two utensil having a same size under a constant heating condition, the utensil of the present invention provides a heating effi- ciency identical to that of the conventional one after period corresponding to 2/3 of that of the conventional one, Therefore, the utensil of the present invention enables the heating time and the consumed amount of fuels to be reduced by about 1/3, as compared with the conventional one with a flat bottom. After the heatresisting and impacting tests, the utensil of the present invention maintains a strong joint force at the jointed area without any separation thereof. Furthermore, the content in the utensil can be uniformly heated, by virtue of eliminating the partially over-heating at the bottom edge of the utensil due to the exposure thereof. In addition, the utensil of the present invention is stable, in virtue of eliminating the possi¬ bility of sliding at the contacting area between the bottom of utensil and a kitchen table or heating equipment.

Claims: What is claimed is: 1. A kitchen utensil comprising a triple bottom joint- ing an aluminum plate and a stainless plate thereto, said utensil being characterized in that the joint portion between said plates is engraved to form recesses of a certain shape at the outwardly exposed lower surface of said stainless plate, adjacent recesses being arranged to have a certain space therebetween, and that the curved peripheral edges of said plates are upwardly extended or curved to the upper end of up-curved bottom edge of said utensil to envelop said bottom edge. 2. A kitchen utensil in accordance with claim 1, wherein the recessed member jointed to the lower surface of said aluminum plate comprises a copper plate. 3. A kitchen utensil in accordance with claim 1, wherein the recessed member jointed to the lower surface of said aluminum plate comprises a brass plate. 4. A method for manufacturing a kitchen utensil with a triple bottom, in which an aluminum plate and a stainless plate are jointed together to the bottom of said utensil by pressing the upper die against the lower die, said method being characterized by the steps of: heating the bottom of said utensil placed on the lower die of conventional construction at , a temperature of 300 to 500°C, said bottom carrying said aluminum plate thereon prior to the heating thereof; disposing said stainless plate on the upper surface of said aluminum plate; and pressing the upper die against the lower die under the pressure of about 400 to 600 kg/cm by using such device as a friction press in order to joint said plates together to the bottom of utensil said upper die having a cavity being so shaped as to upwardly extend or curve the peripheral edges of said plates to envelop up-curved bottom edge of utensil and provided at the inner surface thereof with 5 reliefs so shaped as to form the corresponding recesses on the joint portion between said plates. 5. A method for manufacturing a kitchen utensil with a triple bottom, which an aluminum plate and a stainless plate 10 are jointed together to the bottom of said utensil by using a radio heating device, said method being characterized by the steps of: disposing said aluminum plate and stainless plate on the lower surface of said bottom of utensil previously 15 carried on the lower die of said radio heating device, said plates each being previously provided at the joint portion therebetween with the recesses and the up-curved peripheral edge by using a pressing method; applying a powder type flux to the jointing surfaces 20. between said members to be jointed together; and jointing' said members together in a manner of radio heating.

Inventors: KIM MYUNG SUK, KIM, MYUNG, SUK
Applicants: WOO SUNG CO LTD, WOO SUNG CO., LTD.
Application year: 1986
Main classification: A47J36
IPC codes: A47J27, A47J36, B21D51