A method of treating a cookware bottom

Abstract

The present invention relates to a method of processing a bottom surface of a cookware. The present invention can include: preparing a mold having a hexagonal engraved edge that is continuous in four directions and an engraved dot formed at the center of each hexagonal engraved edge on a surface formed on a circular plate; preparing a three-layer composite plate material having an aluminum intermediate layer and a stainless steel layer adhered to an upper surface and a lower surface; installing the mold in a mold support frame provided on a movable support plate of a rolling roller device; placing the material composite plate thereon so that the surface thereof is positioned in an area in contact with and overlapping the mold installed in the mold support frame; operating the rolling roller device so that rolling is performed by the movement of the movable support plate together with the pressurized rotation of a lower roller; forming a non-stick coating layer on the surface of the material composite plate forming an embossed portion and an engraved portion; and selectively grinding the coating layer applied on the upper surface of the embossed portion to thereby remove it.

Description

TECHNICAL FIELD

[0001] The present invention relates to a cookware used when cooking food, and more particularly, to a method of processing a bottom surface of a cookware, in which a surface of a three-layer composite plate having an aluminum layer interposed therebetween is roll-pressed to form hexagonal embossed portions continuously in four directions, and embossed dots are formed at centers of engraved portions surrounded by the embossed portions, and a non-stick coating is applied only on the engraved portions. BACKGROUND

[0002] In the case of a cookware (e.g., a frying pan or a pot) made of a metallic material, it is configured to receive heat from a heating device when cooking food, thereby cooking food material contained therein, and food material often sticks to a bottom surface of the cookware during cooking, thereby hindering desired cooking, and food residues adhered to the cookware are not easily removed during cleaning, thereby requiring additional time and effort.

[0003] In order to solve the above problem of food material sticking to the bottom surface of the cookware, a cookware having a coating formed on the bottom of the cookware has been widely used in order to have a non-stick function, preventing food material from directly contacting a metallic cookware surface, thereby helping to improve corrosion resistance and non-stick properties.

[0004] As for a new non-stick coating, various materials and lamination schemes for a non-stick coating for a cookware, such as the use of Teflon (main ingredient is a fluororesin), or laminating a resin layer and a ceramic layer together, have been developed to date.

[0005] Meanwhile, a non-stick coating generally exhibits satisfactory functions at the initial stage of use of the cookware, but as time passes and repeated use, the following problems are often encountered: during cooking or washing, the non-stick coating is easily damaged or peeled off due to contact with other objects [particularly a metallic cookware or a washing sponge (e.g., a washing brush)] or due to external impact or friction, thereby failing to perform the intended functions, and shortening the service life of the cookware.

[0006] In order to solve the above problems while retaining the advantages of the non-stick coating, many techniques have recently been proposed, such as the following: a bottom surface of a cookware having a non-stick coating is formed as a corrugated surface, reducing the contact area of food material to be cooked with the bottom surface of the cookware, thereby reducing the possibility of the cooked food sticking to the bottom surface. In addition, the uneven bottom surface reduces the possibility of external objects (e.g., a spatula or a cleaning tool) contacting or impacting the non-stick coating.

[0007] As an example of the prior art related to the above-described cookware having a non-flat bottom surface, Korean Registered Patent No. 10-1392095 discloses a method for manufacturing a bottom surface of a cookware, in which a filter material on which a porous pattern is formed is attached to a stainless steel plate body, thereby forming a resist ink layer pattern; a corrosion solution is sprayed thereon, selective etching is performed, a hexagon which is continuous in four directions is formed, and the surface of the hexagon except for a point portion at the center thereof is cut off; the resulting non-flat bottom surface has a hexagon which is relatively convex and continuous in four directions, a circular dot embossed portion, and an engraved portion which is relatively concave inside the hexagon; and a non-stick coating layer is formed thereon.

[0008] In addition, Korean Registered Patent No. 10-1894663 discloses a cookware manufacturing method similar to the above-described Korean Registered Patent No. 10-1392095, in which a resist ink layer is formed on the surface of a stainless steel plate body; selective surface corrosion is performed by immersing the same in a corrosion solution tank filled with a corrosion solution; the resulting non-flat surface has continuous embossed and engraved portions on the bottom surface; only the engraved portion of the non-flat bottom surface is selectively primed; and a double coating layer is formed by sequentially forming a primer layer, an intermediate coating layer, and a top coating layer.

[0009] However, the above-described method of forming a non-flat bottom surface by exposing the bottom surface of a cookware to an etching solution so that the embossed portion is relatively protruded due to selective etching has the following problems: the method requires film-based resist ink pattern formation processing as processing for selectively etching the surface of a stainless steel plate body which is made of a single material and has a basic thickness; the method also requires many inconvenient processes of exposing or immersing the same in a corrosion solution (an acidic solution) or performing selective etching in the corrosion solution (the acidic solution) according to the formed pattern until the etching is completed; a considerable amount of time is required until the final etching is completed using the corrosion solution; a large work space is required to perform the above-described processing; and the method needs improvement in terms of economic value and production cost.

[0010] In addition, the above-described etching-type non-flat bottom surface formation method uses a corrosion solution for surface etching, which is an acidic solution, and thus involves long-term environmental problems related to handling and disposal of used corrosion solution. SUMMARY

[0011] In view of the above-mentioned disadvantages and problems associated with the use of a corrosive solution in the prior art, a cookware is provided with a bottom surface formed as a non-flat wavy surface, and one aspect of the present application is to provide a method of processing a cookware bottom surface, wherein, unlike a cookware bottom surface having a wavy surface formed by chemical etching as a cause of the above-mentioned problems, cold roll-pressing is used as a physical scheme for forming a non-flat bottom surface including hexagonal embossed portions relatively protruding on a material bottom surface and continuous in four directions, engraved portions surrounded by the embossed portions, and embossed points at the centers of the engraved portions.

[0012] Another aspect of the present application is to provide a method of processing a cookware bottom surface, wherein, unlike a metal plate body made of a single material, a three-layer composite plate including an intermediate layer made of aluminum, which is a flexible material having excellent plastic processing properties, and stainless steel metal sheets adhered to the upper and lower portions thereof is provided as a material to be processed, so that a non-flat surface portion having a wavy pattern on the bottom surface can be formed by the above-mentioned roll-pressing, so that the non-flat surface can be quickly and efficiently formed.

[0013] According to one aspect of the present application, a method of processing a cookware bottom surface can include preparing a mold having hexagonal engraved portions continuous in four directions and embossed points formed at the centers inside the respective hexagonal engraved portions on a surface of a flat circular plate; cutting a three-layer composite plate having an aluminum intermediate layer and metal layers other than aluminum adhered to the upper and lower surfaces of the aluminum intermediate layer, respectively, to prepare a material composite plate; installing the mold in a mold support frame provided on a movable support plate of a roll-pressing roller device; placing a surface of the material composite plate on the mold installed in the mold support frame; operating the roll-pressing roller device while maintaining one side edge of the material composite plate placed on the mold in contact with the lower side of a lower roller of the roll-pressing roller device, so that roll-pressing is performed by the movement of the movable support plate and the pressurized rotation of the lower roller; passing the material composite plate roll-pressed by the mold through a leveler to correct the bending of the material composite plate; spraying a paint solution onto the roll-pressed surface of the material composite plate and drying, so that a non-stick coating layer is formed; grinding and removing the coating layer applied to the upper surface of the embossed portions using a grinder; and drawing the material composite plate into shape, so that the surfaces on which the embossed portions and the engraved portions are formed constitute the bottom surface of the cookware.

[0014] The material composite plate as one of the specific configurations according to the present application can include a three-layer (3-ply) composite plate having an aluminum intermediate layer as the middle thereof and a stainless steel upper layer and a stainless steel lower layer adhered to the upper and lower surfaces of the aluminum intermediate layer, respectively. Preferably, the total thickness of the three-layer composite plate is 2.0-3.0 mm, and the thickness of the aluminum intermediate layer is greater than the sum of the thicknesses of the stainless steel upper and lower layers.

[0015] More preferably, the total thickness of the three-layer composite plate is about 2.3 mm, the upper stainless steel layer is a 304 stainless steel series and can have a thickness of 0.4 mm, the thickness of the aluminum middle layer is 1.4 mm, and the lower stainless steel layer can be a 430 stainless steel series and can have a thickness of 0.5 mm.

[0016] In particular, in the three-layer composite plate, if the lower stainless steel layer constituting the outer surface of the cookware is a 430 stainless steel series, an induction reaction can occur throughout the cookware, thereby providing the cookware with advantages in terms of thermal efficiency and heat retention.

[0017] Meanwhile, the thickness of the upper stainless steel layer directly contacting the mold during the rolling process can be less than or equal to half the thickness of the aluminum middle layer located on the inner side thereof and having a relatively soft material. Thus, when a load is applied in the rolling, the aluminum middle layer located on the inner side can also be plastically deformed together with the upper stainless steel layer. Accordingly, the forming of the surface having a corrugated surface corresponding to the surface shape of the mold can be smoothly performed.

[0018] Thereafter, the rolling roller device used in the rolling of the material composite plate can include an upper roller and a lower roller, the lower roller can be used as a working roller directly contacting the material composite plate to transmit a load thereto, and the upper roller having a larger size can be used as a support roller supporting the working roller in consideration of the bending of the working roller in the process of transmitting the force through the working roller.

[0019] The mold support plate capable of reciprocating horizontally about the lower roller can be positioned below the lower roller, and the surface of the circular plate of the mold having a corrugated surface is located in a mold support frame formed in the center of the upper surface of the mold support plate in an upwardly exposed state.

[0020] Meanwhile, the rolling roller device can perform rolling while changing the rotational direction of the rolling in a state in which the workers are located on both sides of the rolling roller device. That is, in a state in which the material composite plate that has retreated to the opposite side by the rolling is replaced with a new material composite plate and placed thereon, if the rolling roller is rotated in the opposite direction from the previous rotational direction, the material composite plate can be rolled while moving to the opposite worker. Accordingly, the two workers can repeatedly perform the same work, thereby rapidly performing the rolling operation.

[0021] By the roll-pressing process, a hexagonal embossed portion continuously in four directions, an engraved portion surrounded by the hexagonal embossed portion, and an embossed dot protruding from the center of the engraved portion can be formed on the surface of the material composite plate, which is a corrugated surface corresponding to a mold, thereby forming a non-flat bottom surface portion. It should be understood that the "hexagonal embossed portion" is a hexagonal protruding rim having a certain thickness, respectively, and the rim has a hollow space therein, respectively, and the bottom of the hollow space constitutes the engraved portion, respectively.

[0022] By the grinding process, only the coating applied to the upper surface of the hexagonal embossed portion and the embossed dot is removed, and thus the coating of the engraved portion is maintained as it is. Therefore, the bottom surface of the cookware manufactured by the method of the present application can have a surface layer of the embossed portion made of a stainless steel material, which can ensure durability from the viewpoints of corrosion resistance and hygiene, a part of which is exposed, and can also have a coating engraved layer thereunder. Therefore, even if a metal squeegee made of, for example, stainless steel is used, the present application can improve the non-stick property, and can prevent the coating of the engraved portion from being damaged, and in addition, can use a 3M green washing sponge or a 3M iron washing sponge when washing the cookware.

[0023] According to the cookware bottom surface processing method of the present application, plastic deformation by one cold roll-pressing using a roll-pressing roller device is performed to form a bottom surface portion on which embossed portions and engraved portions are alternately and continuously formed. Therefore, compared to the conventional method of forming a corrugated surface of a bottom surface portion by etching, the processing procedure and processing time can be significantly shortened.

[0024] In addition, the method of the present application is advantageous in that roll-pressing is performed by a simple operation, a complicated operation of the roll-pressing roller device is not required, and the roll-pressing roller device itself has a simple structure, thereby reducing the cost or space of equipment required for roll-pressing processing.

[0025] In addition, the present application is not related to environmental problems caused by the conventional etching method using an acidic solution, and thus is eco-friendly. BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1A and FIG. 1B are a schematic perspective view and a longitudinal sectional view, respectively, illustrating a roll-pressing process using the roll-pressing roller device of the present application;

[0027] FIGS. 2A-2D is a sectional view showing a procedure of changing a material composite plate according to the steps of the method of the present application, and in particular,

[0028] FIG. 2A is a sectional view of a material composite plate before roll-pressing,

[0029] FIG. 2Bis a cross-sectional view of a material composite plate after rolling,

[0030] FIG. 2C is a cross-sectional view of a coating applied to the material composite plate after rolling before grinding, and

[0031] FIG. 2D is a cross-sectional view of the material composite plate in which the coating on the upper surface of the embossed portion is removed by grinding processing; and

[0032] FIG. 3A and FIG. 3B are pictures of cookware processed according to the method of the embodiment of the present application, specifically:

[0033] FIG. 3A shows the entire cookware, and

[0034] FIG. 3B shows an enlarged portion. DETAILED DESCRIPTION

[0035] According to the embodiment of the present application, the technical objects and specific roles and effects including specific processes and configurations of the present application can be more clearly understood by the person skilled in the art through the following detailed description of the embodiment attached to the drawings.

[0036] FIG. 1A and FIG. 1B are a schematic perspective view and a longitudinal cross-sectional view, respectively, illustrating a rolling process using the rolling roller device according to the present application, and FIGS. 2A-2D is a cross-sectional view showing the process of changing the material composite plate according to the method of the present application, and specifically, FIG. 2A is a cross-sectional view of a material composite plate before rolling, FIG. 2B is a cross-sectional view of a material composite plate after rolling, FIG. 2C is a cross-sectional view showing a coating applied to the material composite plate after rolling before grinding, FIG. 2D is a cross-sectional view of the material composite plate in which the coating on the upper surface of the embossed portion is removed by grinding processing.

[0037] First, a mold M having hexagonal engraved rims that are continuous in four directions and engraved dots formed on a flat circular plate, in which the engraved dots are formed at the centers of the hexagonal engraved rims, respectively, is manufactured. Then, the mold is fixed in a mold support frame 5 of a movable support plate 4 of a rolling roller device 1 having an upper roller 2 and a lower roller 3, as shown in FIG. 1A and FIG. 1B In this case, the mold M fixed in the mold support frame 5 is stably seated in the mold support frame in a state in which the corrugated surface portion of the mold is located on the same plane as the upper end of the mold support frame 5.

[0038] Next, as shown in FIG. 2A , the material composite plate 10 includes a three-layer composite plate including an aluminum middle layer 11, a stainless steel lower layer 12 adhered to a lower surface of the aluminum middle layer, and a stainless steel upper layer 13 adhered to an upper surface of the aluminum middle layer. The total thickness of the material composite plate 10 can be 2.3 mm, and specifically, the thickness of the stainless steel upper layer 13 can be 0.4 mm, the thickness of the aluminum middle layer can be 1.4 mm, and the thickness of the stainless steel lower layer 12 can be 0.5 mm.

[0039] The material composite plate 10 can be cut into a circular plate shape slightly larger in diameter than the mold M, and as shown in FIG. 1A , can be placed on the mold previously fixed in the mold support frame 5. Next, as shown in FIG. 1B , in a pushed and inserted state in which the movable support plate 4 is in contact with the bottom end of the lower roller 3 of the roll press roller device 1, the roll press roller device 1 is driven so that the material composite plate 10 is in contact with the lower roller 3 and is thus drawn into the same by the rotation of the upper roller 2 and the lower roller 3. Accordingly, the contact surface between the mold M and the material composite plate 10 is pressed by the load transmitted, thereby generating an embossed portion and an engraved portion on the stainless steel upper layer 13 of the material composite plate 10. In this case, the load applied from the roll press roller device 1 can be about 120 tons. FIG. 1A and FIG. 1B , the reference numeral R is a rotating roller having a rod shape and movably supporting the movable support plate 4.

[0040] The roll press processing can be achieved in a process in which the mold M including the material composite plate 10 supplied from one side of the roll press roller device is taken out to the opposite side thereof by the rotation of the lower roller 3, the lower roller 3 being rotated in a state of being pressed and contacted. When the material composite plate 10 is taken out from the lower roller 3, the roll press processing is completed.

[0041] FIG. 2B A cross section of the material composite plate 10 that has undergone the roll press processing is shown. As shown in the drawing, the stainless steel upper layer 13 of the material composite plate 10 can include a non-flat surface having embossed portions Sa protruding as compared to before the roll press as shown in FIG. 2A , and engraved portions Sb relatively recessed formed between the embossed portions Sa, the embossed portions and the engraved portions being continuous. The embossed portions Sa can include embossed points Saa each protruding from the center of each engraved portion Sb surrounded by a corresponding hexagonal protruding portion and continuous in four directions.

[0042] As described above, the flat stainless steel upper layer 13 before rolling can have a non-flat surface including embossed portions Sa and engraved portions Sb arranged in an alternating succession, and have a height difference with respect to its surface due to plastic deformation in the rolling process. Thus, the aluminum intermediate layer 11, which is located below and is a softer material, is also deformed along with the deformation of the stainless steel upper layer 13 during the plastic deformation.

[0043] Next, in order to give the cookware a non-stick property, a coating solution is applied to the surface of the stainless steel upper layer 13 of the material composite plate 10 formed with the embossed portions and engraved portions, thereby forming a coating cl on the entire area thereof, as shown in FIG. 2C A composition of the coating, which is a conventional polytetrafluoroethylene coating material with a fluororesin as the main component, to which a red pigment is added, can be used. As for the thickness of the coating, the thickness range of the coating normally applied to the bottom surface of the cookware can be maintained.

[0044] Next, the coated surface of the material composite plate 10 is ground using a rotary grinder. Only the upper surfaces of the embossed portions Sa and Saa of the stainless steel upper layer 13 are ground, thereby selectively reducing the coating.

[0045] FIG. 2D is a cross-sectional view of the material composite plate from which the coating of the embossed portions Sa and Saa is removed by the grinding process, and the coating cl of the engraved portions Sb other than the upper end surface of the embossed portions can be maintained as is.

[0046] Meanwhile, FIG. 3A and 3B are pictures of cookware processed according to the method of the embodiment of the present application, and in particular, FIG. 3A indicates the entirety of the cookware, FIG. 3B shows an enlarged portion. As shown in the figures, it can be seen that the proportion of the engraved portions Sb is relatively large compared to the proportion of the embossed portions Sa, Saa in the entire area of the bottom surface thereof.

[0047] Brief description of reference numerals

[0048] 1. Rolling roller device

[0049] 2. Upper roller

[0050] 3. Lower roller

[0051] 4. Mobile support plate

[0052] 5. Mould support frame

[0053] M. Mould

[0054] 10. Material composite plate

[0055] 11. Aluminum intermediate layer

[0056] 12. lower layer of stainless steel

[0057] 13. upper layer of stainless steel

[0058] Sa. embossed portion

[0059] Sb. engraved portion

[0060] Saa. embossed dot

Claims

1. A method for processing the bottom surface of a cookware, the method comprising: Prepare a mold having hexagonal engraved edges and engraved points formed on the surface of a circular plate, the hexagonal engraved edges being continuous in four directions and the engraved points being formed at the center of each hexagonal engraved edge; A three-layer composite board is prepared, comprising an aluminum intermediate layer, a stainless steel upper layer, and a stainless steel lower layer. The stainless steel upper layer and the stainless steel lower layer are respectively bonded to the upper and lower surfaces of the aluminum intermediate layer. The thickness of the aluminum intermediate layer is greater than the sum of the thicknesses of the stainless steel upper layer and the stainless steel lower layer. The three-layer composite board is cut into circular plates corresponding to the mold to prepare the material composite board; The circular plate mold is installed in the mold support frame set on the movable support plate of the rolling roller device; The circular composite material plate is placed on the circular plate mold installed within the mold support frame, thereby overlapping with it; The rolling roller device is operated while one edge of the material composite plate placed on the mold is kept in contact with the lower side of the lower roller of the rolling roller device, thereby rolling is performed by moving the movable support plate and applying pressure to rotate the lower roller. A non-stick coating is formed on the surface of the composite material plate on which embossed and engraved portions are formed by rolling. The coating applied to the upper surface of the embossed portion is removed using a grinding machine; as well as The composite material is drawn into shape so that the surface with the embossed and carved parts becomes the bottom of the cookware.

2. The method according to claim 1, characterized in that, The total thickness of the three-layer composite board is 2.0-3.0mm.

3. The method according to claim 1, characterized in that, The embossed section includes continuous hexagonal sections in four directions and embossed dots protruding from the center of the sculpted section surrounded by the corresponding hexagonal sections.

4. The method of claim 1 further comprises, between the rolling and the formation of the coating, passing the composite material through a leveling machine to correct any bending of the composite material produced during the rolling.

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