A composite-bottom cookware, its manufacturing method, and a cooking appliance using the same

Abstract

The present invention relates to a composite-bottom cookware, a manufacturing method thereof, and a cooking appliance using the composite-bottom cookware. The composite-bottom cookware according to an embodiment of the present invention includes: a cookware body having an inner wall and an outer wall; and a penetration rust-proof layer on the inner wall and / or the outer wall of the cookware body; wherein the bottom of the cookware body has a multi-layer structure, and the multi-layer structure includes at least one layer of copper brazing layer, and the copper brazing layer is connected to its adjacent layer. Therefore, the penetration rust-proof treatment of the composite-bottom cookware can be realized, and the problems in the prior art that aluminum will be softened and deformed due to high temperature during the penetration rust-proof treatment, resulting in the composite bottom being unable to be firmly connected, are solved. In addition, using the copper brazing layer for fixed connection can significantly reduce costs and improve production efficiency, and improve the bonding strength between the copper brazing layer and the adjacent layer, which is beneficial to improving the heat conduction speed, thereby improving the heat conduction performance of the cookware and reducing the generation of oil fumes.

Description

Technical Field

[0001] The present invention relates to the field of cooking utensils, and particularly to a composite-bottom cookware, a manufacturing method thereof, and a cooking utensil using the composite-bottom cookware. Background Art

[0002] At present, the stainless steel fine iron cookware on the market is mainly made of a single-layer iron plate or steel plate, and then undergoes an anti-rust treatment through a penetration anti-rust treatment (such as nitriding treatment, etc.). Since this kind of cookware is made of a single-layer, relatively thin, and poor heat-conducting iron or steel material, there are problems such as uneven heat conduction, easy deformation after heating, and easy generation of oil fumes. The product quality is low and the user experience is poor. Referring to the technologies of other material cookware, the above problems can be solved by the method of double-bottoming the cookware. For example, a double-bottom sheet and aluminum as an interlayer are compounded at the bottom of the pot body by pressure welding to thicken the bottom of the pot, improve the heat storage performance of the bottom of the pot, and reduce the generation of oil fumes. However, there is still no such composite-bottom iron pan product in the current industry. The biggest technical bottleneck is that no technical solution has been found to effectively solve the problem of penetration anti-rust treatment (such as nitriding treatment, etc.) of the composite-bottom iron pan: for example, for ordinary nitriding treatment, in order to obtain a good anti-rust layer, the treatment temperature usually exceeds 500 °C. At this time, the double-bottom interlayer metal (usually aluminum alloy, melting point 660 °C) is easily softened or melted, making the double-bottom sheet unable to be firmly combined with the pot body. When the nitriding treatment temperature is reduced to below 500 °C, the time required for nitriding treatment is very long (usually more than 10 hours), and the obtained anti-rust layer is relatively thin. Not only is the manufacturing cycle too long and the cost too high, but also the anti-rust effect is very poor, unable to meet the needs of users. Summary of the Invention

[0003] In order to solve at least one of the above technical problems, the present invention provides a composite-bottom cookware, a manufacturing method thereof, and a cooking utensil using the composite-bottom cookware.

[0004] An embodiment of one aspect of the present invention provides a composite-bottom cookware, including:

[0005] A pot body having an inner wall and an outer wall; and

[0006] A penetration anti-rust layer on the inner wall and / or outer wall of the pot body;

[0007] Wherein, the bottom of the pot body has a multi-layer structure, and the multi-layer structure includes at least one layer of copper brazing layer, and the copper brazing layer is connected to its adjacent layer.

[0008] In some embodiments of the present invention, the copper brazing layer includes pure copper or copper alloy brazing material, and / or the melting point of the pure copper or copper alloy brazing material in the copper brazing layer is 800 °C to 1100 °C.

[0009] In some embodiments of the present invention, the content ratio of copper or copper alloy in the copper brazing layer is greater than 50%.

[0010] In some embodiments of the present invention, the multi-layer structure includes at least one heat dissipation layer, and at least a part of at least one heat dissipation layer is connected to an adjacent layer through a copper brazing layer.

[0011] In some embodiments of the present invention, a diffusion transition layer is formed between the copper brazing layer and the adjacent layer connected thereto.

[0012] In some embodiments of the present invention, the interface morphology of the diffusion transition layer is serrated.

[0013] In some embodiments of the present invention, the thickness of the copper brazing layer is 0.1 mm to 2 mm.

[0014] In some embodiments of the present invention, the multi-layer structure includes a pot body layer and at least one composite bottom layer.

[0015] In some embodiments of the present invention, the multi-layer structure sequentially includes a pot body layer, a first copper brazing layer, a first composite bottom layer, a second copper brazing layer, and a second composite bottom layer. The first composite bottom layer is connected to the pot body layer through the first copper brazing layer, and the first composite bottom layer and the second composite bottom layer are connected through the second copper brazing layer.

[0016] In some embodiments of the present invention, the height of the composite bottom layer is not greater than half of the total height of the composite bottom cookware, and / or both the pot body layer and the composite bottom layer are made of iron-based materials.

[0017] An embodiment of another aspect of the present invention provides a manufacturing method of the above-mentioned composite bottom cookware, including the following steps:

[0018] Step 1, welding at least two metal plates with a copper brazing material to form a composite plate;

[0019] Step 2, performing a forming process on the composite plate to obtain a finished pot body part;

[0020] Step 3, performing infiltration rust prevention treatment on the inner wall and / or outer wall of the finished pot body part to obtain the composite bottom cookware.

[0021] In some embodiments of the present invention, the infiltration rust prevention treatment in Step 3 is ion nitriding treatment.

[0022] In some embodiments of the present invention, step 2 includes first forming the composite plate into the shape of a pot body to obtain an intermediate pot body, and then spinning the intermediate pot body to obtain a finished pot body; the intermediate pot body includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The intermediate pot body has a diameter D1 and a height H1, and the composite bottom layer of the intermediate pot body has a first height h1; the finished pot body includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The finished pot body has a diameter D and a height H, and the composite bottom layer of the finished pot body has a second height h; wherein, the diameter D of the finished pot body is smaller than the diameter D1 of the intermediate pot body, and the second height h of the composite bottom layer of the finished pot body is greater than the first height h1 of the composite bottom layer of the intermediate pot body.

[0023] In some embodiments of the present invention, the first height h1 of the composite bottom layer of the intermediate pot body is less than 25 mm.

[0024] In some embodiments of the present invention, the diameter D1 of the intermediate pot body is 1.25 to 1.67 times the diameter D of the finished pot body.

[0025] In some embodiments of the present invention, the second height h of the composite bottom layer of the finished pot body is not less than 25 mm and not greater than H / 2.

[0026] In some embodiments of the present invention, the composite bottom layer of the intermediate pot body has a first bottom wall and a first side wall connected to the first bottom wall. The composite bottom layer of the intermediate pot body has a first bottom wall diameter d1. The composite bottom layer of the composite bottom pot has a second bottom wall and a second side wall connected to the second bottom wall. The composite bottom layer of the finished pot body has a second bottom wall diameter d, and the second bottom wall diameter d is not greater than the first bottom wall diameter d1.

[0027] In some embodiments of the present invention, the unfolded diameter of the pot body layer is 1% to 5% smaller after spinning than before spinning; the unfolded diameter of the composite bottom layer is 1% to 5% smaller after spinning than before spinning.

[0028] Embodiments of another aspect of the present invention provide a manufacturing method of the above composite bottom pot, including the following steps:

[0029] Step 1, obtaining a plurality of material layers forming a multi-layer structure, and respectively processing the plurality of material layers into the shapes required to form the multi-layer structure;

[0030] Step 2, welding at least two layers of the multi-layer structure with a copper brazing material to obtain a pot body;

[0031] Step 3, performing penetration rust prevention treatment on the inner wall and / or outer wall of the pot body to obtain a composite bottom pot.

[0032] In some embodiments of the present invention, the multi-layer structure in step 2 includes a pot body layer, and copper brazing filler metal is used for welding between the pot body layer and its adjacent layer.

[0033] In some embodiments of the present invention, the anti-rust penetration treatment in step 3 is ion nitriding treatment.

[0034] An embodiment of another aspect of the present invention provides a cooking appliance, including the composite-bottom cookware in the above embodiments.

[0035] The additional aspects and advantages of the present invention will become apparent in the following description section, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0037] Figure 1 is a schematic structural diagram of a composite-bottom cookware according to an embodiment of the present invention;

[0038] Figure 2 is a schematic structural diagram of a composite-bottom cookware without anti-rust penetration treatment according to another embodiment of the present invention;

[0039] Figure 3 is a schematic structural diagram of a composite-bottom cookware without anti-rust penetration treatment according to another embodiment of the present invention;

[0040] Figure 4 is a schematic structural diagram of a composite plate according to another embodiment of the present invention;

[0041] Figure 5 is a schematic structural diagram of a composite-bottom cookware without anti-rust penetration treatment according to another embodiment of the present invention;

[0042] Figure 6 is a schematic structural diagram of a composite-bottom cookware without anti-rust penetration treatment according to another embodiment of the present invention;

[0043] Figure 7 is a schematic structural diagram of a pot body intermediate member according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0045] Reference is made below Figure 1-7 to describe a composite bottom cookware according to an embodiment of the present invention, a manufacturing method thereof, and a cooking appliance using the same.

[0046] A composite bottom cookware according to an embodiment of the present invention, as Figure 1 shown, includes:

[0047] a pot body 1 having an inner wall and an outer wall; and

[0048] a penetration rust prevention layer on the inner wall and / or the outer wall of the pot body; in one embodiment, as Figure 1 shown, the inner wall of the pot body has a penetration rust prevention layer 41, and the outer wall of the pot body has a penetration rust prevention layer 42;

[0049] wherein, the bottom of the pot body has a multi-layer structure, and the multi-layer structure includes at least one copper brazing layer, and the copper brazing layer is connected to its adjacent layer.

[0050] In the embodiments of the present invention, by using a copper brazing layer, since the melting point of the copper brazing material in the copper brazing layer is higher than the temperature of the permeation anti-rust treatment, it will not soften and melt, and the connection reliability of the multi-layer structure can be ensured. Therefore, the permeation anti-rust treatment of the composite bottom cookware can be realized, solving the problem in the prior art that when using aluminum with a lower melting point as the connection material between the composite bottom layer and the pot body layer, the aluminum will soften and deform due to high temperature during the permeation anti-rust treatment, resulting in the inability to firmly connect the pot body layer and the composite bottom layer. In addition, it can also ensure that the production cycle of the permeation anti-rust treatment will not be too long. After setting a multi-layer structure at the bottom of the pot body, the thickness of the bottom of the pot increases, the heat storage performance is improved, and the heating rate slows down during heating. It is easy for users to control the temperature of the cookware not to exceed the smoke point temperature of the cooking oil. Therefore, it is beneficial to reduce the generation of oil fumes. In addition, the thermal conductivity of copper material is higher than that of iron and aluminum. Using a copper brazing layer can improve the thermal conductivity of the bottom of the pot, make the temperature of the bottom of the pot more uniform, avoid local high temperature to make the cooking oil reach the smoke point temperature, and reduce the generation of oil fumes. In addition, compared with the composite board process (that is, each board material is made into a composite board by pressure welding, such as rolling, explosion, etc., and then the pot body is formed), when the copper brazing material in the copper brazing layer is welded to the adjacent layer, the copper brazing material is in a molten state, and the mutual diffusion and dissolution with the adjacent layer will be strengthened. Therefore, a connection interface that is tighter than that of the composite board can be formed, with a higher bonding strength with the adjacent layer, which can ensure heat conduction while increasing the controllability of the gap between the multi-layer structures, and is beneficial to improving the heat conduction speed between the layers, thereby improving the thermal conductivity of the cookware. In the present invention, the adjacent layer connected to the copper brazing layer refers to the layer in the multi-layer structure that is directly in contact with the copper brazing layer for welding. The permeation anti-rust layer formed on the inner wall and / or outer wall of the pot body has good corrosion resistance and anti-rust performance, will not rust due to the contact between the pot body and water, and improves the user experience of the pot.

[0051] In another embodiment of the present invention, the permeation anti-rust layer 41 or 42 can be formed on the inner wall and / or outer wall of the pot body by using permeation anti-rust treatments such as nitriding, carbonitriding, and oxygen permeation. Gas nitriding, ion nitriding, and liquid nitriding can be selected for nitriding treatment. Preferably, the ion nitriding method is selected for nitriding treatment because during ion nitriding, the workpiece does not contact the solution, the workpiece is not easily corroded, and ion nitriding can be carried out at a lower temperature, which is more beneficial to the stability of the multi-layer structure connection. In addition, the production method of ion nitriding is more environmentally friendly, and the generated products after treatment will not affect the environment. Preferably, the nitriding temperature is controlled within the range of 500°C to 700°C. This temperature range is lower than the melting point temperature of the copper brazing layer. After nitriding, the copper brazing layer will not soften and deform, ensuring the strength of the cookware. In addition, it can also ensure that the nitriding production cycle will not be too long, and the formed permeation anti-rust layer has good anti-rust performance.

[0052] In another embodiment of the present invention, the copper brazing layer comprises pure copper or a copper alloy brazing material, and / or the melting point of the pure copper or copper alloy brazing material in the copper brazing layer is 800°C to 1100°C. In one embodiment, as Figure 1 shown, the copper brazing layer comprises a single layer of copper brazing layer 21. The copper brazing material uses pure copper brazing material with a relatively high thermal conductivity and a melting point reaching 1083°C. This not only enables the pot body to have better thermal conductivity, but also the melting point of pure copper is higher, making it less likely to soften and deform at the high temperature during the anti-rust layer penetration treatment, ensuring the strength of the pot body. Since the price of pure copper brazing material is relatively high, in order to reduce the material cost, a copper alloy with a melting point greater than 800°C can also be used as the raw material of the copper brazing material. It can be understood that multiple layers of copper brazing layers can be provided, and the compositions of the multiple layers of copper brazing layers can be the same or different. The temperature range of the melting point of the pure copper or copper alloy brazing material is at least 100°C higher than the temperature range of the nitriding treatment of 500°C to 700°C, which can ensure that the copper brazing material will not soften due to the high temperature of nitriding, reduce the strength of the double bottom, and affect the thermal conductivity of the cookware. Further, the content ratio of copper or copper alloy in the copper brazing layer is greater than 50%, which is beneficial to ensuring the thermal conductivity of the copper brazing layer. Preferably, in addition to pure copper or copper alloy, the copper solder also includes other components that help improve the welding quality, including but not limited to: borax, boric acid, alkali metals, alkaline earth metal fluorides, alkaline earth metal chlorides, etc.

[0053] In another embodiment of the present invention, the multi-layer structure further comprises a pot body layer and at least one double bottom layer. In one embodiment, as Figure 1 shown, the multi-layer structure comprises a pot body layer 11, a single layer of copper brazing layer 21, and a single layer of double bottom layer 31. The pot body layer 11 and the double bottom layer 31 are welded through the copper brazing layer 21, and both the pot body layer 11 and the double bottom layer 31 are made of iron-based materials. In this embodiment, the double bottom layer is a single layer. When a better smokeless effect needs to be achieved, the bottom of the pot usually needs to reach a certain thickness. At this time, the thickness of the single-layer double bottom layer needs to be increased. However, the thermal conductivity of iron-based materials is relatively slow. Increasing the thickness of the double bottom layer will increase the thermal resistance and reduce the thermal conductivity, which is not conducive to the heating performance of the cookware. Therefore, a multi-layer double bottom layer solution is proposed, that is, two or more double bottom layers are provided at the bottom of the pot body, and copper brazing is still used for welding connection between the double bottom layers and between the pot body layer and the double bottom layer. The beneficial effect of this solution is that: at the same bottom thickness of the pot, the thickness of each double bottom layer can be set smaller, reducing the thermal resistance and making the longitudinal thermal conductivity of the double bottom layer faster. At the same time, copper brazing layers are provided between the double bottom layers and between the pot body layer and the double bottom layer, and the copper brazing layer enables the transverse conduction of heat to be faster. By using multiple double bottom layers and multiple copper brazing layers, the longitudinal and transverse thermal conductivities of the double bottom layer can be improved, making the thermal conductivity of the cookware better and conducive to improving the cooking effect. In one embodiment, as Figure 2Schematic structural diagram of a composite bottom cookware with unpenetrated rust prevention treatment. The multi-layer structure of the cookware body 2 sequentially includes a cookware body layer 12, a first copper brazing layer 22, a first composite bottom layer 32, a second copper brazing layer 23, and a second composite bottom layer 33. The first composite bottom layer 32 is welded to the cookware body layer 12 through the first copper brazing layer 22, and the first composite bottom layer 32 and the second composite bottom layer 33 are welded through the second copper brazing layer 23. Moreover, the cookware body layer 12, the first composite bottom layer 32, and the second composite bottom layer 33 can all be made of iron-based materials. In one embodiment, the iron-based material can be pure iron, steel, or other iron-containing materials commonly used for cookware bodies. Steel, for example, can be carbon steel or stainless steel, etc.

[0054] In another embodiment of the present invention, the multi-layer structure further includes at least one heat dissipation layer, and at least a part of the at least one heat dissipation layer is connected to the adjacent layer through a copper brazing layer. As Figure 3 Schematic structural diagram of a composite bottom cookware with unpenetrated rust prevention treatment according to an embodiment of the present invention. The multi-layer structure of the cookware body 3 includes a third copper brazing layer 211, a heat dissipation layer 212, and a fourth copper brazing layer 213. The heat dissipation layer 212 is located between the third copper brazing layer 211 and the fourth copper brazing layer 213, and the composite bottom layer 31 is brazed to the bottom of the cookware body layer 11 through two copper brazing layers and one heat dissipation layer. The heat dissipation layer in the present invention is generally made of a material with a higher thermal conductivity than that of the composite layer or the cookware body layer, such as aluminum, copper, or their alloys, etc. Preferably, the heat dissipation layer is a copper sheet layer. By adding a uniform heat dissipation layer between the cookware body layer 11 and the composite bottom layer 31, the problem that the copper brazing layer formed by the copper brazing material may have different thermal conductivities at different positions due to uneven density everywhere can be improved. Of course, two or more heat dissipation layers can also be used. For example, when two heat dissipation layers are used, the materials of the two heat dissipation layers can be the same, such as both being copper sheet layers, or different, such as one being copper and the other being aluminum or steel. Between the heat dissipation layers, between the heat dissipation layer and the cookware body layer, and between the heat dissipation layer and the composite bottom layer, copper brazing layers are used for connection. Similarly, after two heat dissipation layers form a composite plate, the above composite plate and the cookware body, as well as the above composite plate and the composite bottom layer, are both connected by copper brazing layers. Additionally, it can be understood that the copper brazing material used for the copper brazing layer in the present invention can be in the form of powder, paste, plate, etc., or a combination of copper brazing materials in the form of powder, paste, plate, etc. and copper plates (heat dissipation layers).

[0055] In another embodiment of the present invention, a diffusion transition layer is formed between the copper brazing filler metal layer and the adjacent layer connected thereto. Compared with the composite plate process (i.e., a process in which various sheet materials are pressure-welded, such as rolling, explosion, etc., to form a composite plate, and then a pot body is formed), when the copper brazing filler metal in the copper brazing filler metal is welded to the adjacent layer, the copper brazing filler metal is in a molten state, and the welding temperature is 800°C to 1200°C, which is 200°C to 400°C higher than the processing temperature of the iron-copper composite plate. The Cu in the copper brazing filler metal and the atoms in the adjacent layer diffuse and dissolve with each other more strongly, forming a diffusion transition layer. Therefore, a connection interface that is more tightly connected than that of the composite plate can be formed, having a higher bonding strength with the adjacent layer, and being beneficial to improving the heat conduction speed between the layers, thereby improving the heat conduction performance of the cookware. In some embodiments, the interface morphology of the diffusion transition layer is serrated, so that the copper brazing filler metal layer and the adjacent layer connected thereto can obtain good bonding force, ensuring the welding effect.

[0056] In another embodiment of the present invention, preferably, the thickness of the copper brazing filler metal layer is 0.1 mm to 2 mm. Within this thickness range, the copper brazing filler metal layer has sufficient strength for connection and good heat conduction performance; if the thickness of the copper brazing filler metal layer exceeds 2 mm, that is, the thickness is too large, since the hardness of copper is much lower than that of iron, it will affect the strength of the pot. For example, the composite bottom part is prone to dent after being collided. In addition, an overly thick copper brazing filler metal layer will also cause a significant increase in cost, which is not conducive to mass production and affects the popularization and application of the technology.

[0057] In another embodiment of the present invention, the height of the composite bottom layer is not greater than half of the total height of the composite bottom cookware. The cookware has a mouth part. The total height of the composite bottom cookware refers to the vertical distance from the bottom of the composite bottom cookware to the mouth part. Since the composite bottom layer is provided on the bottom surface of the pot body, it has a shape adapted to the bottom surface of the pot body and also has a mouth part. The height of the composite bottom layer refers to the vertical distance from the bottom of the composite bottom layer to the mouth part. If the height of the composite bottom layer exceeds half of the total height of the composite bottom cookware, its coverage range far exceeds the heating range of ordinary cookware, which belongs to excessive composite bottom coverage, resulting in material waste and cost increase.

[0058] In another embodiment of the present invention, the manufacturing method of the composite bottom cookware in the above embodiment of the present invention includes the following steps:

[0059] Step 1, at least two metal plates are welded with a copper brazing filler metal to form a composite plate. In one embodiment, as Figure 4 shown, the metal sheet 10 used for the pot body layer and the metal sheet 30 used for the composite bottom layer can be welded together through the copper brazing filler metal layer 20 to form a composite plate 4. The advantage of this process is that brazing can be carried out in a flat state, and induction brazing and other methods can be used. When brazing, the upper and lower welding heads press the sheet material and then weld, making the welding tighter, improving the welding quality, and making the heat conduction performance of the welded bottom of the pot better.

[0060] Step 2, perform a forming process on the composite plate to obtain a finished pot body part. For example, the composite plate material is formed into a pot body shape through processes such as die drawing, spinning, or hydroforming. This step usually also includes processes such as trimming and turning to remove excess materials. After the composite plate is formed, in one embodiment, as Figure 5 shown, the obtained first finished pot body part 5 has a pot body layer 11 and a composite bottom layer 31 fixedly connected to the pot body layer 11 through a copper brazing layer 21. In this embodiment, the composite bottom layer 31 and the copper brazing layer 21 can cover the bottom and part of the side wall of the pot body layer 11. After the composite plate is formed, in another embodiment, as Figure 6 shown, the obtained second finished pot body part 6 has a pot body layer 13 and a composite bottom layer 34 fixedly connected to the pot body layer 13 through a copper brazing layer 24. In this embodiment, the composite bottom layer 34 and the copper brazing layer 24 can only roughly cover the bottom of the pot body layer 13.

[0061] Step 3, perform an infiltration rust prevention treatment on the inner wall and / or outer wall of the finished pot body part to obtain a composite bottom cookware. The infiltration rust prevention treatment process is as described in the foregoing embodiments and will not be elaborated here.

[0062] The advantage of using a composite plate to manufacture the composite bottom cookware in this embodiment is that the thickness is uniform everywhere, the thickness is easy to control, the thickness of different material layers can be adjusted according to different needs, the processing process is simple, and effects such as optimized design, weight reduction, performance improvement, and cost reduction can be achieved. The composite bottom cookware made of a composite plate has a greater bottom thickness than a single-layer fine iron cookware, better heat storage capacity, and more uniform heat conduction. Therefore, it is not easy to generate oil fumes during the cooking process.

[0063] In another embodiment of the present invention, further, Step 2 includes first forming the composite plate into a pot body shape to obtain a pot body intermediate part, and then spinning the pot body intermediate part to obtain a finished pot body part; the pot body intermediate part includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The pot body intermediate part has a diameter D1 and a height H1, and the composite bottom layer of the pot body intermediate part has a first height h1; the finished pot body part includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The finished pot body part has a diameter D and a height H, and the composite bottom layer of the finished pot body part has a second height h; wherein, the diameter D of the finished pot body part is smaller than the diameter D1 of the pot body intermediate part, and the second height h of the composite bottom layer of the finished pot body part is greater than the first height h1 of the composite bottom layer of the pot body intermediate part. In one embodiment, as Figure 4 、 5As shown in FIGS. 7, first, the composite plate 4 is formed into the shape of a pot body to obtain the pot body intermediate 7, and then the pot body intermediate 7 is spin - formed to obtain the first pot body finished part 5; the pot body intermediate 7 includes a pot body layer 14 and a composite bottom layer 35 fixedly connected to the pot body layer 14 through a copper brazing layer 25. The pot body intermediate 7 has a diameter D1 and a height H1, and the composite bottom layer 35 has a first height h1; the first pot body finished part 5 has a diameter D and a height H, and the composite bottom layer 31 has a second height h; wherein, the diameter D of the first pot body finished part 5 is smaller than the diameter D1 of the pot body intermediate 7, and the second height h of the composite bottom layer 31 is greater than the first height h1 of the composite bottom layer 35.

[0064] The mouth of a general pot body is circular. Therefore, the diameter of the pot body intermediate or the pot body finished part refers to the maximum diameter of the mouth (as shown in FIGS. Figure 5 , 7 , including the wall thickness), and the height refers to the vertical distance from the bottom to the mouth. Since the composite bottom layer is connected to the bottom of the pot body layer, it has a shape adapted to the bottom surface of the pot body layer, has a mouth, and the height of the composite bottom layer refers to the vertical distance from the bottom to the mouth of the composite bottom layer. In this embodiment of the present invention, by first manufacturing the pot body intermediate, since the composite bottom layer of the pot body intermediate has a smaller first height h1, when combining the composite bottom layer of the pot body intermediate with the pot body layer, the bonding effect between the composite bottom layer and the pot body layer can be improved, such as having higher bonding strength and reliability, being more firmly bonded and not having problems such as false soldering, air pockets or delamination, etc., thereby improving the heat conduction performance of the composite bottom cookware. Further, by means of spin - forming, the side wall of the pot body intermediate is spin - formed, so that the fillet of the lower side wall of the pot body intermediate becomes smaller, the height becomes higher, and the mouth diameter becomes smaller, and finally the shape required by the product is achieved to obtain the pot body finished part. At this time, the pot body finished part has a larger height H, a smaller diameter D, and a larger second height h of the composite bottom layer. By first manufacturing the pot body intermediate and then performing spin - forming, a composite bottom cookware with a high - position composite bottom is finally obtained. Through this process method, the height of the composite bottom layer of the manufactured composite bottom cookware meets the use requirements of simultaneous heating of the bottom and the side, that is, there is a composite bottom layer on both the bottom and the side wall of the composite bottom cookware, greatly improving the heat conduction performance of the bottom and the side of the composite bottom cookware, making the temperature distribution of the composite bottom cookware more uniform, thereby achieving the effect of less fumes and ensuring the health of users. In addition, spin - forming forms the required shape of the pot body layer and the composite bottom layer through pressure. After spin - forming, the connection between the pot body and the composite bottom layer will be closer, which will further improve the heat conduction performance of the composite bottom layer. At the same time, after spin - forming, the spin - forming device will form annular micro - patterns on the outer surface of the composite bottom layer. These micro - patterns increase the surface area of the composite bottom layer, can accelerate the heat conduction speed of the composite bottom layer, and improve the heat conduction performance of the pot body.

[0065] In another embodiment of the present invention, the first height h1 of the composite bottom layer 35 of the pot body middleware 7 is less than 25 mm. In this way, when combining the composite bottom layer of the pot body middleware and the pot body layer, it can be ensured that the height of the composite bottom layer does not exceed the limit of the bonding process, thereby ensuring a reliable and firm connection between the composite bottom layer and the pot body layer after bonding, and laying a good foundation for subsequent spinning processing.

[0066] In another embodiment of the present invention, the diameter D1 of the pot body middleware is 1.25 to 1.67 times the diameter D of the finished pot body. When converting the pot body middleware into a finished pot body through spinning processing, it is necessary to fully consider the process limit of spinning forming and the reasonable distribution of the height of the composite bottom layer in order to determine the ratio of the diameter D1 of the pot body middleware to the diameter D of the finished pot body. If the value of D1 is too small, the first height h1 of the composite bottom layer must also be reduced due to the limit of the bonding process between the composite bottom layer and the pot body layer, which may result in the inability of the final second height h of the composite bottom layer to meet the requirements of the high-position composite bottom. If the value of D1 is too large, the material on the side wall of the pot body middleware during spinning may wrinkle or break due to excessive deformation. Therefore, considering the above factors comprehensively and through actual test verification, the value range of D1 is set as D1 = (1.25 - 1.67)D.

[0067] In another embodiment of the present invention, the second height h of the composite bottom layer of the finished pot body is not less than 25 mm and not greater than H / 2. If h is too small, it does not belong to the high-position composite bottom, and the significance of using the process of the present invention is not great. If h is too large, its coverage range far exceeds the heating range of an ordinary pot body, which means that the composite bottom covers too much, resulting in material waste and cost increase. Therefore, a more reasonable value range for h is 25 mm ≤ h ≤ H / 2. Through the manufacturing method of the present invention, the problem that the existing welding process cannot achieve a high-position composite bottom pot with a height greater than 25 mm is solved, and a pot body with a high-position composite bottom is obtained.

[0068] In another embodiment of the present invention, the composite bottom layer of the pot body middleware has a first bottom wall and a first side wall connected to the first bottom wall. The composite bottom layer of the pot body middleware has a first bottom wall diameter d1. The composite bottom layer of the composite bottom pot has a second bottom wall and a second side wall connected to the second bottom wall. The composite bottom layer of the finished pot body has a second bottom wall diameter d, and the second bottom wall diameter d is not greater than the first bottom wall diameter d1. In one embodiment, as Figure 7 shown, the composite bottom layer 35 of the pot body middleware 7 has a first bottom wall diameter d1, and the composite bottom layer 31 of the first finished pot body 5 has a second bottom wall diameter d, and the second bottom wall diameter d is not greater than the first bottom wall diameter d1. If d1 is designed to be d1 < d, then during the spinning process, the bottom wall of the pot body middleware may be deformed, which will affect the dimensional accuracy of the obtained composite bottom pot.

[0069] In another embodiment of the present invention, the unfolded diameter of the pot body layer is 1% - 5% smaller before spinning than after spinning; the unfolded diameter of the composite bottom layer is 1% - 5% smaller before spinning than after spinning. In a general manufacturing process, the surface areas of the pot body layer and the composite bottom layer of the pot body intermediate are generally consistent with those of the finished pot body. However, if higher manufacturing precision is required, considering that the material becomes slightly thinner after spinning, the surface areas of the pot body layer and the composite bottom layer can be appropriately reduced. The unfolded diameters of the pot body layer and the composite bottom layer can be reduced by 1% - 5%.

[0070] In another embodiment of the present invention, the manufacturing method of the composite bottom cookware in the above embodiment of the present invention includes the following steps:

[0071] Step 1: Obtain multiple material layers forming a multi-layer structure, and process each of the multiple material layers into the shape required to form the multi-layer structure; for example, each of the multiple material layers can be formed by processes such as die drawing, spinning, or hydroforming.

[0072] Step 2: Weld at least two of the structures in the multi-layer structure using copper brazing filler metal to obtain the pot body; in one embodiment, the multi-layer structure in Step 2 includes a pot body layer, and copper brazing filler metal is used to weld between the pot body layer and its adjacent layer. Through the copper brazing filler metal layer, welding is carried out by brazing. The high temperature generated by the brazing equipment melts the copper brazing filler metal, so that at least two structures are connected together. For the layers that are not welded with copper brazing filler metal, other welding methods such as pressure welding can be used. The two welding methods act synergistically. Pressure welding can further promote the bonding force between the brazing filler metal and the metal layer and increase the bonding effect.

[0073] Step 3: Perform penetrative rust prevention treatment on the inner wall and / or outer wall of the pot body to obtain the composite bottom cookware. The penetrative rust prevention treatment process is as described in the foregoing embodiment and will not be elaborated here. In this embodiment, after processing each of the multiple material layers into the shape required to form the multi-layer structure, brazing welding is carried out. It is easy to control the thickness or shape of the multi-layer structure at each place, the processing process is simple, the production cost can be significantly reduced, and the production efficiency can be improved. Similarly, for the composite bottom cookware made using this process, the thickness of the bottom and / or side wall of the pot body is greater than that of a single-layer fine iron cookware, the heat storage capacity is better, and the heat conduction is more uniform. Therefore, it is not easy to generate oil fumes during the cooking process.

[0074] The cooking appliance in another embodiment of the present invention includes the composite bottom cookware in the above embodiment. The cooking appliance is, for example, various cookware or other common cooking appliances, etc.

[0075] It should be understood that the terms used herein are for the purpose of describing specific exemplary embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or their combinations. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the particular order described or illustrated, unless the order of performance is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0076] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0077] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A composite-bottom cookware, characterized in that, Comprising: A pot body having an inner wall and an outer wall; and A permeable rust-proof layer on the inner wall and / or outer wall of the pot body; Wherein, the bottom of the pot body has a multi-layer structure, The multi-layer structure includes a pot body layer, two copper brazing layers, a heat dissipation layer and a composite bottom layer. The two copper brazing layers are respectively a third copper brazing layer and a fourth copper brazing layer. The heat dissipation layer is located between the third copper brazing layer and the fourth copper brazing layer. The composite bottom layer is brazed to the bottom of the pot body layer through the two copper brazing layers and one heat dissipation layer, and the copper brazing layer is connected to its adjacent layer; The pot body layer is connected to its adjacent layer through the copper brazing layer; A diffusion transition layer is formed between the copper brazing layer and its adjacent layer; the interface morphology of the diffusion transition layer is serrated; The heat dissipation layer is made of aluminum material; The copper brazing layer includes pure copper or copper alloy brazing material, and the melting point of the pure copper or copper alloy brazing material in the copper brazing layer is 800°C to 1100°C; The thickness of the copper brazing layer is 0.1mm to 2mm; The height of the composite bottom layer is not less than 25mm and not more than half of the total height of the composite bottom cookware. Both the pot body layer and the composite bottom layer are made of iron-based materials.

2. The composite-bottom cookware according to claim 1, wherein: The content ratio of copper or copper alloy in the copper brazing layer is greater than 50%.

3. The composite bottom cookware according to claim 1, wherein: At least part of the heat dissipation layer is connected to the adjacent layer through the copper brazing layer.

4. The composite bottom cookware according to claim 1, characterized in that: The composite bottom layer includes a first composite bottom layer and a second composite bottom layer. The first composite bottom layer is brazed to the bottom of the pot body layer through the two copper brazing layers and one heat dissipation layer. The second composite bottom layer is connected to the first composite bottom layer through a second copper brazing layer.

5. A manufacturing method of the composite bottom cookware according to any one of claims 1-4, characterized in that, Including the following steps: Step 1, welding at least two metal plates with copper brazing material to form a composite plate; Step 2, performing a forming process on the composite plate to obtain a finished pot body part; Step 3, performing a permeable rust-proof treatment on the inner wall and / or outer wall of the finished pot body part to obtain a composite bottom cookware.

6. The manufacturing method of the composite bottom cookware according to claim 5, characterized in that: The permeable rust-proof treatment in Step 3 is ion nitriding treatment.

7. According to the manufacturing method of the composite bottom cookware as claimed in claim 5, wherein: Step 2 includes first forming the composite plate into the shape of a pot body to obtain an intermediate pot body part, and then spinning the intermediate pot body part to obtain a finished pot body part; the intermediate pot body part includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The intermediate pot body part has a diameter D1 and a height H1, and the composite bottom layer of the intermediate pot body part has a first height h1; the finished pot body part includes a pot body layer and a composite bottom layer fixedly connected to the pot body layer through a copper brazing layer. The finished pot body part has a diameter D and a height H, and the composite bottom layer of the finished pot body part has a second height h. Wherein, the diameter D of the finished pot body part is smaller than the diameter D1 of the intermediate pot body part, and the second height h of the composite bottom layer of the finished pot body part is greater than the first height h1 of the composite bottom layer of the intermediate pot body part.

8. The manufacturing method of the composite bottom cookware according to claim 7, characterized in that: The first height h1 of the composite bottom layer of the intermediate pot body part is less than 25mm.

9. The manufacturing method of the composite bottom cookware according to claim 7, characterized in that: The diameter D1 of the intermediate pot body part is 1.25 to 1.67 times the diameter D of the finished pot body part.

10. The manufacturing method of the composite bottom cookware according to claim 7, characterized in that: The composite bottom layer of the pot body intermediate piece has a first bottom wall and a first side wall connected to the first bottom wall. The composite bottom layer of the pot body intermediate piece has a first bottom wall diameter d1. The composite bottom layer of the composite bottom cookware has a second bottom wall and a second side wall connected to the second bottom wall. The composite bottom layer of the finished pot body piece has a second bottom wall diameter d, and the second bottom wall diameter d is not greater than the first bottom wall diameter d1.

11. The manufacturing method of the composite bottom cookware according to claim 7, characterized in that: The unfolded diameter of the pot body layer is 1% - 5% smaller before spinning than after spinning; the unfolded diameter of the composite bottom layer is 1% - 5% smaller before spinning than after spinning.

12. A manufacturing method of the composite bottom cookware according to any one of claims 1-4, characterized in that, It includes the following steps: Step 1: Obtain multiple material layers forming the multi-layer structure, and process each of the multiple material layers into the shape required to form the multi-layer structure. Step 2: Weld at least two of the structures in the multi-layer structure using copper brazing filler metal to obtain a pot body. Step 3: Perform penetration rust prevention treatment on the inner wall and / or outer wall of the pot body to obtain a composite bottom cookware.

13. The manufacturing method of the composite bottom cookware according to claim 12, characterized in that, In Step 2, the multi-layer structure includes a pot body layer, and copper brazing filler metal is used for welding between the pot body layer and its adjacent layer.

14. The manufacturing method of the composite bottom cookware according to claim 12, characterized in that, The penetration rust prevention treatment in Step 3 is ion nitriding treatment.

15. A cooking appliance, including the composite bottom cookware according to any one of claims 1 - 4.

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