DESC:TECHNICAL FIELD
[001] The embodiments herein generally relate to a cooking utensil, more particularly but not exclusively to a cooking utensil having at least one of a bottom surface and a body made of a multilayer material and adapted for a gas burner, hot plate, electric stove, fuel stove and an induction cooking device oil-free cooking and less oil cooking and a manufacturing method thereof.
BACKGROUND
[002] Cooking utensils are basic tool used daily in human life. Despite having different shapes of cookware, ranging from a barbecue grill to a fry pan, the basic elements of a cookware are two surfaces: one for receiving heat from a heat source, and the other for heating the food. Heat energy generated either from electricity, or a burning flame, is transferred from the source to the heat-receiving surface of the cookware, which is conducted through the cookware and transferred to the food.
[003] In conventional kitchen utensils attention has been paid to distribute the heat evenly across the base of the utensils. However, with respect to combustion cooking, there has been partial effort made to improve the energy receiving end of the process, i.e., the energy transfer efficiency from the flame to the utensil is typically low. Some prior art teaches to have concentric grooves on the bottom surface of the cooking utensil, and coating them with radiation absorbing coating to improve the heat absorption. Other attempts provide cooking utensils with patterned features that can improve the heat transfer laterally. The primary aim is to improve electric-source heat at the center and bottom of the cookware. Another attempt has been made to improve heat conduction by using concentric rings in the cookware base. However, the shallow grooves result in inadequate improvement on heat transfer.
[004] A conventional cooking utensil of a type, which is subjected to a magnetic field induced by an exciter and heated by the heat appearing as a result of eddy-current loss is available. The conventional cooking utensils of the aforementioned type are made of iron, e.g. cast iron or enameled iron, or 18Cr-8Ni or 18Cr stainless steel. However, they are heavier than those made of other materials. Moreover, the utensils made of iron are liable to rusting, and those made of enameled iron are likely to have the enamel separated from the iron.
[005] Aluminum has been used since many years for making a variety of cooking utensils, and for making a cooking utensil for heating by an electromagnetic induction, too. It comprises a vessel made of aluminum and having a bottom to which a different magnetic metal is bonded. It, however, still poses a lot of drawbacks. The metal bonded to the bottom is liable to rusting and separation from the aluminum body. The bonding of the metal makes the utensil awkward in appearance and expensive to manufacture. Moreover, it is not comparable to a cooking pan of iron or enameled iron in heating efficiency unless its magnetic metal layer has a considerably large thickness.
[006] Therefore, there exists a need for a cooking utensil and a method of manufacturing the same, which obviates the aforementioned drawbacks.
OBJECTS
[007] The principal object of the embodiments disclosed herein is to provide a cooking utensil having at least one of a bottom surface and a body made of a multilayer material.
[008] Another object of the embodiments disclosed herein is to provide a cooking utensil including at least one of a bottom and a full body made up of different metals for improved heat conductivity, energy efficiency, oil-free or less-oil cooking, appearance, wear resistance and corrosion resistance.
[009] Yet another object of the embodiments disclosed herein is to provide a cooking utensil to be used on a gas stove, hot plate, electric stove, fuel stove and an induction cooking device and also for oil-free or less oil cooking.
[0010] Still another object of the embodiments disclosed herein is to provide a method of manufacturing a cooking utensil having at least one of a bottom surface and a body made of a multilayer material.
[0011] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0012] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0013] FIG. 1 depicts a front view of a cooking utensil having at least one of a bottom surface and a body made of a multilayer material of predetermined materials, according to an embodiment of the invention as disclosed herein;
[0014] FIG. 2 depicts a top view of a cooking utensil having at least one of a bottom surface and a body made of a multilayer material of predetermined materials, according to an embodiment of the invention as disclosed herein; and
[0015] FIG. 3 is a flowchart depicting a method of manufacturing a cooking utensil having at least one of a bottom surface and a body made of a multilayer material of predetermined materials, according to an embodiment of the invention as disclosed herein.

DETAILED DESCRIPTION
[0016] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0017] The embodiments herein achieve a cooking utensil having at least one of a bottom surface and a body made of a multilayer material. Further, the embodiments herein achieve a cooking utensil including at least one of a bottom and a full body made up of different metals for improved heat conductivity, energy efficiency, oil-free or less-oil cooking, appearance, wear resistance and corrosion resistance. Furthermore, the embodiments herein achieve a cooking utensil to be used on a gas stove, hot plate, electric stove, fuel stove and an induction cooking device and also for oil-free or less oil cooking. Referring now to the drawings, and more particularly to FIGS. 1 through 4, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0018] FIGS. 1 and 2 depict a front view and a top view of a cooking utensil having at least one of a bottom surface and a body made of a multilayer material of predetermined materials, according to an embodiment of the invention as disclosed herein. In an embodiment, the cooking utensil 100 (also referred to as cookware in this description) includes a body 102, a base portion 104 (also referred as bottom surface or bottom portion of cooking utensil), a side portion 106, and at least one metal layer 108 applied to at least one of the base portion 104 and the body 102.
[0019] The cooking utensil 100 is made of any shape and size. The cooking utensil 100 includes the body 102 having the base portion 104 and the side portion 106 extending from the base portion 104. The bottom portion 104 and the side portion 106 together define an inner surface (not shown) adapted to receive food and an outer surface (not shown) adapted to be exposed to a heat source. The cooking utensil 100 is made up of a first predetermined material. The first predetermined material may be selected but not limited to at least one of copper, aluminum, iron and stainless steel.
[0020] The cooking utensil 100 further includes the at least one metal layer 108. The metal layer 108 is disposed on the outer surface of the cooking utensil 100. In an alternate embodiment, the metal layer 108 may be disposed on the inner surface of the cooking utensil 100 or may be sprayed on both side of utensil bottom and body or even same process can be applied before drawing/forming the cooking utensil. The metal layer 108 is deposited on the cooking utensil by an arc spray. The metal layer 108 is an arc-sprayed layer of a second predetermined material. The second predetermined material is selected from but not limited to at least one of, ferromagnetic metal, a thermally conductive metal, scratch resistant metal, corrosion resistant metal and a combination thereof. Further, the second predetermined material includes but not limited to at least one of aluminum, copper, stainless less, carbon steel, SS430, 400-series ferritic stainless steel, and combination thereof. The metal layer 108 is sprayed on at least one of the bottom portion 104 and the body 102 for a predetermined thickness of 0.025mm to 10mm.
[0021] The metal layer 108 is disposed on at least one of the bottom surface 104 and the body 102 in at least one of circular, a spiral, a concentric circular manner and a combination thereof.
[0022] FIG. 3 is a flowchart depicting a method of manufacturing a cooking utensil having at least one of a bottom surface and a body made of a multilayer material of predetermined materials, according to an embodiment of the invention as disclosed herein. A method 300 of manufacturing a cooking utensil having at least one metal layer is provided. At step 302, the method includes providing a cooking utensil 100 having a body 102, said body 102 having a bottom portion 104 and a side portion 106 extending from said bottom portion 104 and formed of a first predetermined material. At step 304, the method includes roughening and cleaning said at least one of said bottom portion 104 and said body 102 of said cooking utensil. At step 306, the method includes applying at least one metal layer 108 of second predetermined material onto said roughened and cleaned said at least one of said bottom portion 104 and said body 102. At step 308, allowing said cooking utensil 100 coated with said metal layer 108 to cool down to a predetermined temperature. At step 310, the method includes polishing said metal layer 108.
[0023] The method according to FIG. 3 is explained below. The cooking utensil 100 is first subjected to a roughening process, for example grit blast. For the purposes of this description and ease of understanding, the embodiments of this invention are explained considering the roughening process to be grit blasting. However, it is also within the scope of this invention to use sand emery and other types of roughening process to roughen the bottom portion 104 and the body 102 of cooking utensil.
[0024] The cooking utensil 100 is initially grit blasted using alumina to attain a predetermined surface roughness. The grit blasting process includes at least one blasting gun mounted on a horizontal reciprocation device to cover entire bottom portion 104 and the body 102 of cooking utensil 100. The cooking utensil 100 is rotated on a turn table at preset RPM. Then the process of blasting operation is initiated from a home position and the reciprocation starts the blasting process at predefined speed. The reciprocation speed is synchronized with the turn table speed. Blasting process starts to blast the cooking utensil bottom portion 104 and the body 102 with blasting grit includes but not limited to Al2O3 (alumina) grit of 40 mesh. However, it is also within the scope of the invention to provide any mesh sized grit of alumina without otherwise deterring the intended function of roughening as can be deduced from the description. A pressure of 25 to 100 psi, preferably 30 psi is applied for blasting the cooking utensil bottom portion 104 and the body 102. The blasting gun to cooking utensil standoff distance is maintained in between 5mm to 1000mm, preferably 150mm. Further, angle for grit attack of the blasting gun to cookware bottom portion 104 and the body 102, is maintained in between 30?-90?, preferably 90? angle of attack. The surface roughness of the blasted surface is in the range of 2.5 – 25 microns, preferably 6 microns for greater adhesion strength of coating. A masking plate may be used for restricting blasting area and/or creating design patterns. After roughening process, the grit blasted cooking utensil bottom portion 104 and the body 102 is cleaned with dry compressed air. For the purposes of this description and ease of understanding, the embodiments of this invention are explained considering the dry compressed air for cleaning. However, it is also within the scope of the invention to provide any type of cleaning means without otherwise deterring the intended function of cleaning as can be deduced from the description.
[0025] After roughening and cleaning, at least one of the bottom portion 104 and the body 102 is subjected to thermal spraying. The thermal spraying is an arc spraying wherein at least two wires, which are consumable electrodes, are drawn from spools to form a liquid droplet due to arc heating and are accelerated by compressed air. The arc spraying may further include at least one spray gun (not shown) having a nozzle to dispose the molten metal. The jet of air acts to atomize the molten wire and to propel the finely atomized particle to the substrate. The two wires used may be made of at least one of same material or different materials, thereby pseudo-alloy coatings can be produced by this type of arc spraying. The current applied for spraying ranges between 150-400amps. The current required for this process is determined by other operating parameters such as arc current, primary atomizing gas pressure, and secondary atomizing gas pressure on spray pattern size, spray pattern flatness, spray pattern eccentricity, and coating deposition rate. The pressure of dry-air is in the range of 20 to 100 psi. Further, a voltage applied on the wires may range from 19 V to 42 V. A wire-feed-rate may be varied from 25 to 250gm/minute. The arc gun to cooking utensil bottom portion’s 104 standoff distance is maintained in between 10 to 1000 mm, preferably 150mm. And a wire diameter used for spraying may range between 0.8-2.0mm, preferably 1.6mm.
[0026] In a first embodiment, at least one of the blasted cooking bottom portion 104 and the body 102 may be exposed to arc spraying to apply at least one metal layer, preferably a ferromagnetic material layer. The at least one of bottom portion 104 and the body 102 is coated with at least one layer of ferromagnetic material to enable the cooking utensil 100 to be used for induction cooking device. The arc spraying process includes a supply of dry compressed air at 75psi. Further, the current and voltage applied during the process are 300 Amperes and 30-36 V respectively. The relatively humidity during the arc spraying process is kept less than 85%. The standoff distance between the spray gun and the cooking utensil ranges from 10 to 1000 mm, preferably 150mm. Further, the feed rate at which the metal is applied to the cooking utensil bottom portion 104 and the body 102 ranges between 75-85 g/min. The metal is coated (coating thickness) for about 0.025 to 10mm, preferably 0.2 mm. The coating thickness may be measured using an electronic thickness gauge. After coating, the cooking utensil 100 is air-cooled to room temperature to reduce internal stresses in the coating.
[0027] In a second embodiment, the blasted cooking bottom portion 104 and the body 102 may be exposed to arc spraying by applying at least one metal layer of thermal conductive material layer. At least one of the cooking utensil bottom portion 104 and the body 102 is coated with at least one layer of thermal conductive material layer, for example aluminum. The arc spray process is carried out by using arc spray with wet type dust collector machine and the coating is performed in a closed area so as to reduce reactions between sprayed material and the ambient air, which in turn would lead to surface oxidation. The arc spraying process includes a supply of dry compressed air at 85 psi. Further, the current and voltage applied during the process are 200 Amperes and 30-33 V respectively. The relatively humidity during the arc spraying process may kept less than 85%. The standoff distance between the spray gun and the cooking utensil ranges from 10 to 1000 mm, preferably 150mm. Further, the feed rate at which the metal is applied to the cooking utensil bottom portion 104 and the body 102 ranges between 60-65 g/min. The metal is coated (coating thickness) for about 0.025 to 10mm, preferably 0.2 mm. The coating thickness is measured using the electronic thickness gauge. After coating, the cooking utensil 100 is air-cooled to room temperature to reduce internal stresses in the coating.
[0028] In a third embodiment, the blasted cooking bottom portion 104 and the body 102 is exposed to arc spraying by applying at least one layer of thermal conductive material layer, for example pure copper. The arc spraying process includes a supply of dry compressed air at 95psi. Further, the current and voltage applied during the process are 200 Amperes and 30-33 V respectively. The relative humidity during the arc spraying process is kept less than 85%. The standoff distance between the spray gun and the cooking utensil ranges from 10 to 1000 mm, preferably 150mm. Further, the feed rate at which the metal is applied to the cooking utensil bottom portion 104 and the body 102 ranges between 90-95 g/min. The metal is coated (coating thickness) for about 0.025 to 10 mm, preferably 0.2mm. The coating thickness is measured using the electronic thickness gauge. After coating, the cooking utensil 100 is air-cooled to room temperature to reduce internal stresses in the coating.
[0029] Further, the arc sprayed cooking utensil 100 having at least one layer of any material is subjected to a polishing process. The cooking utensil 100 is held using fixture spindle, which has vacuum pump to provide grip. A polishing head rotates is rotated in a range between 300 -2800 RPM, preferably at 2000 RPM. Further the polishing head is mounted to a tool holder having an indexing system. The polishing head or the cutting tool cuts the sprayed material surface to get an even surface. The tool is indexed automatically. In an alternate embodiment, an additional pneumatic tool will polish the sprayed material rough edges of the cooking utensil bottom portion 104 and the body 102, and it operates automatically while the surface cutting operation is in process. The tool speed and pressure is operated in accordance with predetermined parameters like, time, speed, polishing compound, turning tool, buffing wheels, buffing compounds etc to get desired finish, pattern and design.
[0030] For the purposes of this description and ease of understanding, the embodiments of this invention are explained considering the polishing tool head for cleaning. However, it is also within the scope of the invention to provide any type of polishing process without otherwise deterring the intended function of polishing as can be deduced from the description.
[0031] The invention has been developed primarily for use in cooking utensil application and is described with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. The skilled person in the art may apply all such process, parameters and the same process of making such multilayer utensils before forming or drawing the component. Further, the embodiments herein may be used on sheet metal or sheet circle before forming the utensil.
[0032] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:We claim,
1. A cooking utensil 100, comprising:
a body 102, said body 102 having a bottom portion 104 and a side portion 106 extending from said bottom portion 104 and formed of a first predetermined material, said bottom portion 104 and said side portion 106 defining an inner surface adapted to receive food and an outer surface 108 adapted to be exposed to a heat source; and
at least one metal layer 108 sprayed to said at least one of said bottom portion 104 and said body 102, wherein,
said metal layer 108 is an arc-sprayed layer of a second predetermined material; and
said second predetermined material is selected from at least one of, ferromagnetic metal, a thermally conductive metal, scratch resistant metal, corrosion resistant metal and a combination thereof.

2. The cooking utensil 100 as claimed in claim 1, wherein said metal layer 108 is sprayed on said at least one of said bottom portion 104 and said body 102 for a predetermined thickness of 0.025 to 10 mm.

3. The cooking utensil 100 as claimed in claim 1, wherein said second predetermined material is selected from at least one of aluminium, copper, stainless less, carbon steel, SS430, 400-series ferritic stainless steel, and combination thereof.

4. The cooking utensil as claimed in claim 1, wherein said metal layer 108 is disposed on said at least one of said bottom portion 104 and said body 102 in at least one of circular, a spiral, a concentric circular manner and a combination thereof.
5. A method 300 of manufacturing a multilayer cooking utensil, said method 300 comprising steps of:
providing a cooking utensil 100 having a body 102, said body 102 having a bottom portion 104 and a side portion 106 extending from said bottom portion 104 and formed of a first predetermined material;
roughening and cleaning said at least one of said bottom portion 104 and said body 102 of said cooking utensil 100;
applying at least one metal layer 108 onto said roughened and cleaned at least one of said bottom portion 104 and said body 102;
allowing said cooking utensil 100 coated with said metal layer 108 to cool down to a predetermined temperature; and
polishing said metal layer 108,
wherein,
said metal layer 108 is an arc-sprayed layer of a second predetermined material; and
said second predetermined material is selected from at least one of, ferromagnetic metal, a thermally conductive metal, scratch resistant metal, corrosion resistant metal and a combination thereof.

6. The method as claimed in claim 5, wherein said metal layer 108 is sprayed on said at least one of said bottom portion 104 and said body 102 for a predetermined thickness of 0.025mm to 10 mm.