A coating-free liner and a manufacturing method thereof

Abstract

The application discloses a non-coating inner container and a manufacturing method thereof, and belongs to the field of electric rice cookers. In view of the poor non-sticking effect of the existing non-coating non-stick pot, the technical scheme is as follows: a non-coating inner container comprises a container main body formed of a composite material, the composite material comprises an inner layer and an outer layer, the inner layer is stainless steel or titanium, and the outer layer is aluminum or aluminum-stainless steel; a concave-convex network pattern is etched or mechanically formed on the inner surface of the inner layer to form a non-stick layer; the non-stick layer comprises an integral groove and a plurality of convex platforms; the groove separates the convex platforms; the total area of the convex platforms is greater than the total area of the groove; the groove depth is greater than or equal to 0.3 mm and less than 0.6 mm; and the gap between two adjacent convex platforms is 0.2 mm to 0.4 mm. The concave-convex non-stick layer is etched or mechanically formed, the integral groove has a proper width and depth, the effect of reducing the residual starch colloid dry adhesion after taking rice is obvious, and the non-sticking effect is relatively good.

Description

Technical Field

[0001] This invention belongs to the field of rice cooker inner pots, and specifically relates to an uncoated inner pot and its manufacturing method. Background Technology

[0002] To prevent rice from sticking, most existing rice cookers, pressure cookers, and other cooking appliances use non-stick coatings. However, the coating often lacks adhesion to the substrate and is prone to peeling off. This can lead to accidental ingestion of coating debris when serving rice. Therefore, more and more consumers desire uncoated inner pots that offer both non-stick properties and easy cleaning. Current technology improves non-stick performance by using an uncoated inner pot and controlling the temperature during cooking to reduce water loss from the rice paste. However, even with this method, the introduction of cold air during rice serving causes residual starch on the pot wall to dry quickly and adhere to the metal inner pot, making cleaning difficult. Existing uncoated inner pots often use textured surfaces to address the non-stick issue. However, experiments with various textured surfaces have shown that different grid patterns have varying effects on non-stick performance; an improperly designed texture can actually be less effective than a textureless inner pot. For example, when the etched patterns commonly used in woks are applied to uncoated inner pots, the non-stick effect is very poor. This is because the etched patterns in woks are characterized by narrow ridges and large pits. When applied to uncoated inner pots, on the one hand, they trap the rice grains, making it difficult to remove them from the pot; on the other hand, the small contact area between the rice scoop and the ridges makes it difficult to scrape out the rice grains from the pits. Currently, uncoated inner pots used in rice cookers on the market have not effectively solved the non-stick problem. Summary of the Invention

[0003] To address the problem of poor non-stick performance in existing uncoated non-stick pans, this invention provides an uncoated inner pot and its manufacturing method, which has a non-stick layer formed by etching or mechanical molding, resulting in an uncoated inner pot with better non-stick performance.

[0004] The technical solution adopted in this invention is as follows: an uncoated inner liner, comprising an inner liner body formed of a composite material, the composite material comprising an inner layer and an outer layer, the inner layer being stainless steel or titanium, the outer layer being stainless steel, aluminum, or aluminum-stainless steel, the inner surface of the inner layer being etched or mechanically formed with a network pattern of concave and convex shapes to form a non-stick layer, the non-stick layer comprising an integral groove and multiple protrusions, the groove separating the protrusions, the total area of ​​the protrusions being greater than the total area of ​​the groove, the groove depth being greater than or equal to 0.3 mm and less than 0.6 mm; the gap between two adjacent protrusions being greater than or equal to 0.2 mm and less than or equal to 0.4 mm.

[0005] The grooves act as a barrier, breaking up the adhesive starch colloids. This significantly reduces the amount of residual starch colloids that stick together after the rice has dried. Seamless, one-piece grooves provide better results, preventing large, clumped areas. The area of ​​the protrusions enclosed by the polygonal sides, along with the groove width and depth, affects the non-stick effect. The gap between two adjacent protrusions is the groove width, which should be between 0.2mm and 0.4mm. A width less than 0.2mm is not conducive to shaping or breaking up the adhesive starch colloids, while a width greater than 0.4mm allows the starch colloids to gelatinize and stick together within the groove. Rice is granular, and cooked rice is coated with a layer of elastic starch hydrocolloid. When the groove width is small enough, the starch within the groove is easily carried out.

[0006] As an optimization, the total area of ​​the bosses is greater than or equal to twice the area of ​​the grooves, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean.

[0007] Furthermore, the protrusion shape can be a regular hexagon, a circle, a chamfered equilateral triangle, a regular octagon, or a deformed dodecagon. The deformed dodecagon is formed by eliminating the three adjacent sides of three adjacent regular hexagons. The included angles also affect non-stick properties; sharper angles are less desirable. Sharp angles increase friction when scooping out rice. To achieve a better non-stick effect, sharp angles should be avoided. Since equilateral triangles have sharp angles, the triangles are chamfered to remove these sharp angles and ensure a non-stick effect.

[0008] Furthermore, when the boss is a regular hexagon, the area of ​​the regular hexagon is greater than or equal to 0.9 mm². 2 Less than or equal to 6mm 2 Its side length is 0.6 to 1.5 mm, preferably 1 mm, and the gap between two adjacent regular hexagons is preferably 0.3 mm.

[0009] Furthermore, when the boss is circular, the diameter of the circle is greater than or equal to 1.2 mm and less than or equal to 3.5 mm, preferably 1.5 mm; the gap between two adjacent circles is greater than or equal to 0.2 mm and less than or equal to 0.3 mm, preferably 0.2 mm.

[0010] Furthermore, when the boss is a chamfered equilateral triangle, the side length of the chamfered equilateral triangle is greater than or equal to 1.5 mm and less than or equal to 5 mm, the chamfer radius is greater than or equal to 0.3 mm, and the gap between two adjacent chamfered equilateral triangles is greater than or equal to 0.2 mm and less than or equal to 0.3 mm.

[0011] Furthermore, when the boss is a regular octagon, the area of ​​the regular octagon must be greater than or equal to 1.2 mm². 2 Less than or equal to 11mm 2 Its side length is greater than or equal to 0.5mm and less than or equal to 1.5mm.

[0012] Furthermore, when the boss is a deformed dodecagon, the side length of the deformed dodecagon is preferably 0.8 mm, and the gap between two adjacent deformed dodecagons is preferably 0.3 mm.

[0013] Furthermore, the inner pot body has a bottom and side walls, and the non-stick layer is fully distributed on the bottom and side walls.

[0014] The above-mentioned method for manufacturing an uncoated inner liner includes the following steps:

[0015] Step 1, Creating a non-stick layer: A textured surface is formed on the surface of the composite material sheet using chemical etching or mechanical embossing / roller embossing to create a non-stick layer; wherein the composite material includes an inner layer and an outer layer, the inner layer being stainless steel or titanium, the outer layer being aluminum or aluminum-stainless steel, and the non-stick layer being located on the surface of the inner layer;

[0016] Step 2, forming the inner pot body: The stretching die stretches the sheet metal under hydraulic mechanical traction to form the inner pot body in the shape of the inner pot, so that the non-stick layer is located on the inner surface of the inner pot body, and then the excess pot opening material is removed by the die on the punch press.

[0017] Step 3, Degreasing: Pickling removes the stretching oil adhering to the inner and outer surfaces of the inner liner body, followed by drying;

[0018] Step 4, Polishing: Polish the inner and outer surfaces of the inner pot body after degreasing. The specific process is as follows: inner surface sanding - outer surface sanding - inner surface nylon wheel polishing - outer surface nylon wheel polishing - outer surface hemp wheel polishing - inner surface hemp wheel polishing - outer surface brushing sand base - inner surface sand base brushing - laser marking of cooking water level line;

[0019] Step 5, Cleaning and Passivation: Remove residual dirt (rust, dust, polishing wax, etc.) from the surface by ultrasonic water washing (with wax remover added); the specific process is as follows: ultrasonic cleaning (with wax remover added) - ultrasonic pure water rinsing - room temperature passivation (with stainless steel passivation solution added) - room temperature pure water rinsing - room temperature air drying and dehydration.

[0020] The method in this application, which first prepares the non-stick layer and then stretches it into the inner pot body, has the advantages of providing multiple options for processing the raised and recessed textures on the flat metal surface, being easy to implement, and having the advantages of reasonable cost and high processing efficiency. If the non-stick layer is processed on the surface of the inner pot after molding, the difficulty increases significantly, the cost is high, and the effect is poor. By rationally designing the shape of the non-stick layer and combining multiple processes such as mechanical forming and surface passivation, a non-coated metal cookware with multiple excellent properties such as wear resistance and durable physical non-stick properties is formed.

[0021] The beneficial effects of this invention are as follows: This application is for an uncoated inner liner and its preparation method. A non-stick layer is formed by etching or mechanically shaping a network pattern with concave and convex surfaces. The molding is easy and cost-effective, and the processing efficiency is high. The one-piece groove is seamlessly connected and has a suitable width and depth, which can play a role in cutting the adhesion of starch colloids. It has a significant effect on reducing the adhesion of residual starch colloids after rice is dried, and the cutting effect is relatively good. Attached Figure Description

[0022] Figure 1 This is a diagram of the non-adhesive layer structure in Example 1;

[0023] Figure 2 This is a diagram of the non-adhesive layer structure in Example 2;

[0024] Figure 3 This is a diagram of the non-adhesive layer structure in Example 3;

[0025] Figure 4 This is a diagram of the non-adhesive layer structure in Example 4;

[0026] Figure 5 This is a diagram of the non-adhesive layer structure in Example 5;

[0027] Figure 6 (a)-(c) are the original images of the uncoated inner liner of Example 1, Comparative Example 1 and Comparative Example 2, respectively;

[0028] Figure 7 (a)-(c) are diagrams of the inner surface structure of the uncoated inner liner of Example 1, Comparative Example 1 and Comparative Example 2, respectively.

[0029] Figure 8 (a)-(c) are surface views of the uncoated inner pots of Example 1, Comparative Example 1 and Comparative Example 2 when the rice is scooped out within 1 minute after it is cooked;

[0030] Figure 9 (a)-(c) are surface views of the uncoated inner pots of Example 1, Comparative Example 1 and Comparative Example 2 when the rice is served within 2 minutes after it is cooked;

[0031] Figure 10(a)-(c) are surface views of the uncoated inner liner of Example 1, Comparative Example 1 and Comparative Example 2 after 1 hour of heat preservation using the 6-cup rice sweet mode. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0033] Example 1

[0034] The uncoated inner liner of this embodiment includes an inner liner body formed of a composite material. The composite material includes an inner layer and an outer layer. The inner layer is made of 304 stainless steel (grade 0Cr18Ni9), and the outer layer is made of 430 stainless steel (grade 10Cr17). The inner surface of the inner layer is etched or mechanically formed with a network pattern to form a non-stick layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses. The total area of ​​the bosses is greater than the total area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. In this embodiment, the groove depth is 0.5 mm.

[0035] The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean. The boss is hexagonal in shape, such as... Figure 1 As shown, the side length of the regular hexagon is 1 mm, and the gap between two adjacent regular hexagons is 0.3 mm.

[0036] The inner pot body has a bottom and side walls, and the non-stick layer is fully covered on the bottom and side walls.

[0037] Example 2

[0038] The uncoated inner liner of this embodiment includes an inner liner body formed of a composite material. The composite material includes an inner layer and an outer layer. The inner layer is made of 304 stainless steel (grade 0Cr18Ni9), and the outer layer is made of 430 stainless steel (grade 10Cr17). The inner surface of the inner layer is etched or mechanically formed with a network pattern to form a non-stick layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses. The total area of ​​the bosses is greater than the total area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. In this embodiment, the groove depth is 0.5 mm.

[0039] The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean. For example... Figure 2 As shown, the boss is circular in shape, the diameter of the circle is 1.5mm, and the gap between two adjacent circles is 0.2mm.

[0040] The inner pot body has a bottom and side walls, and the non-stick layer is fully covered on the bottom and side walls.

[0041] Example 3

[0042] The uncoated inner liner of this embodiment includes an inner liner body formed of a composite material. The composite material includes an inner layer and an outer layer. The inner layer is made of 304 stainless steel (grade 0Cr18Ni9), and the outer layer is made of 430 stainless steel (grade 10Cr17). The inner surface of the inner layer is etched or mechanically formed with a network pattern to form a non-stick layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses. The total area of ​​the bosses is greater than the total area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. In this embodiment, the groove depth is 0.5 mm.

[0043] The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean. For example... Figure 3 As shown, the boss is shaped like a chamfered equilateral triangle. The side length of the chamfered equilateral triangle is preferably 1.3 mm, the chamfer radius is greater than or equal to 0.5 mm, and the gap between two adjacent chamfered equilateral triangles is 0.3 mm.

[0044] The inner pot body has a bottom and side walls, and the non-stick layer is fully covered on the bottom and side walls.

[0045] Example 4

[0046] The uncoated inner liner of this embodiment includes an inner liner body formed of a composite material. The composite material includes an inner layer and an outer layer. The inner layer is made of 304 stainless steel (grade 0Cr18Ni9), and the outer layer is made of 430 stainless steel (grade 10Cr17). The inner surface of the inner layer is etched or mechanically formed with a network pattern to form a non-stick layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses. The total area of ​​the bosses is greater than the total area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. In this embodiment, the groove depth is 0.5 mm.

[0047] The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean. For example... Figure 4 As shown, the boss is shaped like a regular octagon; when the boss is shaped like a regular octagon, the area of ​​the regular octagon must be greater than or equal to 1.2 mm². 2 Less than or equal to 11mm 2 Its side length is 1mm, and the gap between two adjacent regular octagons is 0.3mm.

[0048] The inner pot body has a bottom and side walls, and the non-stick layer is fully covered on the bottom and side walls.

[0049] Example 5

[0050] The uncoated inner liner of this embodiment includes an inner liner body formed of a composite material. The composite material includes an inner layer and an outer layer. The inner layer is 304 stainless steel (grade 0Cr18Ni9), and the outer layer is aluminum alloy (grade AL1100) - 430 stainless steel (grade 10Cr17), wherein the aluminum alloy is between 304 stainless steel and 430 stainless steel. A network pattern of raised and recessed areas is etched or mechanically formed on the inner surface of the inner layer to form a non-stick layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses, and the total area of ​​the bosses is greater than the total area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm; in this embodiment, the groove depth is 0.5 mm.

[0051] The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove, and the area of ​​each boss is greater than or equal to 0.9 mm². 2 Less than or equal to 11mm 2 At this point, the non-stick effect is better, processing is convenient, and the inner liner is easy to clean. For example... Figure 5As shown, the protrusion is a deformed dodecagon, which is formed by eliminating the three adjacent sides of three adjacent regular hexagons; the side length of the deformed dodecagon is 0.8mm, and the gap between two adjacent deformed dodecagons is preferably 0.3mm.

[0052] The inner pot body has a bottom and side walls, and the non-stick layer is fully covered on the bottom and side walls.

[0053] Example 6

[0054] This embodiment describes the preparation method of the uncoated inner liner of Examples 1 to 5, including the following steps:

[0055] Step 1, Creating a non-stick layer: A non-stick layer is formed on the surface of the composite material sheet (the composite sheet is purchased from the market) by chemical etching or mechanical embossing / rolling. The composite material includes an inner layer and an outer layer. The inner layer is stainless steel or titanium, and the outer layer is aluminum or aluminum-stainless steel. The non-stick layer is located on the surface of the inner layer.

[0056] Step 2, forming the inner pot body: The stretching die stretches the sheet metal under hydraulic mechanical traction to form the inner pot body in the shape of the inner pot, so that the non-stick layer is located on the inner surface of the inner pot body, and then the excess pot opening material is removed by the die on the punch press.

[0057] Step 3, Degreasing: Pickling removes the stretching oil adhering to the inner and outer surfaces of the inner liner body, followed by drying;

[0058] Step 4, Polishing: Polish the inner and outer surfaces of the inner pot body after degreasing. The specific process is as follows: inner surface sanding - outer surface sanding - inner surface nylon wheel polishing - outer surface nylon wheel polishing - outer surface hemp wheel polishing - inner surface hemp wheel polishing - outer surface brushing sand base - inner surface sand base brushing - laser marking of cooking water level line;

[0059] Step 5, Cleaning and Passivation: Remove residual dirt (rust, dust, polishing wax, etc.) from the surface by ultrasonic water washing (with the addition of a wax remover); the specific process is as follows: ultrasonic cleaning (with the addition of a wax remover) - ultrasonic pure water rinsing - room temperature passivation (with the addition of stainless steel passivation solution) - room temperature pure water rinsing - room temperature air drying. The degreaser is model HDL-1071 (MSDS), the wax remover is model RCA68, and the passivator is model A69.

[0060] Comparative Example 1

[0061] The inner liner is made of commercially available materials and is hexagonal with a side length of 1.6mm and a depth of 0.1mm.

[0062] Comparative Example 2

[0063] It uses a smooth, uncoated inner liner available on the market.

[0064] Rice was cooked in the inner pots of Example 1, Comparative Example 1, and Comparative Example 2 respectively, and the non-stick effect was observed and compared. Figures 6 to 10 As shown, Figure 6 (a)-(c) are the original images of the uncoated inner liner of Example 1, Comparative Example 1 and Comparative Example 2, respectively; Figure 7 (a)-(c) are diagrams of the inner surface structure of the uncoated inner liner of Example 1, Comparative Example 1 and Comparative Example 2, respectively.

[0065] The surface images of the uncoated inner pots of Example 1, Comparative Example 1, and Comparative Example 2 are as follows: When the rice is scooped out within 1 minute of cooking, the images are as follows: Figure 8 (a)-(c) show that Example 1 has the best non-stick effect, and Comparative Example 2 also has a better non-stick effect than Comparative Example 1.

[0066] The surface images of the uncoated inner pots of Example 1, Comparative Example 1, and Comparative Example 2 are as follows: When the rice is served within 2 minutes after cooking, the images show the following: Figure 9 (a)-(c) show that Example 1 has the best non-stick effect, and Comparative Example 2 also has a better non-stick effect than Comparative Example 1.

[0067] When the rice is scooped out within 3 minutes after it is cooked, in Example 1, the scooping force is small and the rice is scooped out smoothly. There is less rice sticking to the bottom of the pot after scooping out the rice, and it is relatively easy to clean. In Comparative Example 1, the rice sticks to the pot, is not easy to scoop out, and is very difficult to clean. In Comparative Example 2, the rice is scooped out smoothly, but there is more rice residue, which increases the difficulty of cleaning after it is left to sit.

[0068] After keeping warm for 1 hour using the 6-cup rice sweetness mode, the surface images of the uncoated inner liner of Example 1, Comparative Example 1, and Comparative Example 2 are as follows: Figure 10 (a)-(c) show that Example 1 has the best non-stick effect, and Comparative Example 2 also has a better non-stick effect than Comparative Example 1.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. An uncoated inner liner, comprising an inner liner body formed of composite material, characterized in that, The composite material comprises an inner layer and an outer layer. The inner layer is made of stainless steel or titanium, and the outer layer is made of stainless steel, aluminum, or aluminum-stainless steel. A non-stick layer is formed by etching or mechanically shaping a network of raised and recessed patterns on the inner surface of the inner layer. The non-stick layer includes an integral groove and multiple protrusions. The groove separates the protrusions. The total area of ​​the protrusions is greater than or equal to twice the area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. The gap between two adjacent protrusions is greater than or equal to 0.2 mm and less than or equal to 0.4 mm. The area of ​​each protrusion is greater than or equal to 0.9 mm² and less than or equal to 11 mm². The protrusion shape is a regular hexagon, a circle, a chamfered equilateral triangle, a regular octagon, or a deformed dodecagon. The deformed dodecagon is formed by eliminating the three adjacent sides of three adjacent regular hexagons.

2. The uncoated inner liner according to claim 1, characterized in that, When the boss is a regular hexagon, the area of ​​the regular hexagon is greater than or equal to 0.9 mm² and less than or equal to 6 mm², its side length is 0.6 to 1.5 mm, and the gap between two adjacent regular hexagons is 0.3 mm.

3. The uncoated inner liner according to claim 1, characterized in that, When the boss is circular, the diameter of the circle is greater than or equal to 1.2 mm and less than or equal to 3.5 mm, and the gap between two adjacent circles is greater than or equal to 0.2 mm and less than or equal to 0.3 mm.

4. The uncoated inner liner according to claim 1, characterized in that, When the boss is a chamfered equilateral triangle, the side length of the chamfered equilateral triangle is greater than or equal to 1.5 mm and less than or equal to 5 mm, the chamfer radius is greater than or equal to 0.3 mm, and the gap between two adjacent chamfered equilateral triangles is greater than or equal to 0.2 mm and less than or equal to 0.3 mm.

5. The uncoated inner liner according to claim 1, characterized in that, When the boss is a regular octagon, the area of ​​the regular octagon must be greater than or equal to 1.2 mm² and less than or equal to 11 mm², and its side length must be greater than or equal to 0.5 mm and less than or equal to 1.5 mm.

6. The uncoated inner liner according to claim 1, characterized in that, When the boss is a deformed dodecagon, the side length of the deformed dodecagon is 0.8 mm, and the gap between two adjacent deformed dodecagons is 0.3 mm.

7. A method for manufacturing an uncoated inner liner, characterized in that, Includes the following steps: Step 1, Creating the Non-stick Layer: A non-stick layer is formed on the surface of the composite material sheet using chemical etching or mechanical embossing / roller embossing. The composite material comprises an inner layer and an outer layer. The inner layer is stainless steel or titanium, and the outer layer is aluminum or aluminum-stainless steel. The non-stick layer is located on the surface of the inner layer. The non-stick layer includes an integral groove and multiple bosses. The groove separates the bosses. The total area of ​​the bosses is greater than or equal to twice the area of ​​the groove. The groove depth is greater than or equal to 0.3 mm and less than 0.6 mm. The gap between two adjacent bosses is greater than or equal to 0.2 mm and less than or equal to 0.4 mm. The area of ​​each boss is greater than or equal to 0.9 mm² and less than or equal to 11 mm². The boss shape is a regular hexagon, a circle, a chamfered equilateral triangle, a regular octagon, or a deformed dodecagon. The deformed dodecagon is formed by eliminating the three adjacent sides of three adjacent regular hexagons. Step 2, forming the inner pot body: The stretching die stretches the sheet metal under hydraulic mechanical traction to form the inner pot body in the shape of the inner pot, so that the non-stick layer is located on the inner surface of the inner pot body, and then the excess pot opening material is removed by the die on the punch press. Step 3, Degreasing: Pickling removes the stretching oil adhering to the inner and outer surfaces of the inner liner body, followed by drying; Step 4, Polishing: Polish the inner and outer surfaces of the degreased inner liner body; Step 5, Cleaning and Passivation: Remove residual dirt from the surface by ultrasonic water washing.

Images