Patent ID: 12220079

In the drawings:1. metal sheet;2. heating furnace;3. rolling machine;4. knurling machine;5. metal composite plate;51. first surface;52. second surface;53. convex part;54. concave part;10. pan body;11. titanium metal layer;12. base metal layer;13. steel metal layer;14. first convex part;15. concave part;16. second convex part;17. oxidation layer;171. first oxidation layer;172. second oxidation layer;173. pore;18. handle; and19. flange.

DETAILED DESCRIPTION OF EMBODIMENTS

The embodiments of the present disclosure will now be described in detail with the examples thereof shown in the drawings throughout which, the same or similar reference signs refer to the same or similar elements or elements with the same or similar functions. The embodiments based on the implementations are intended to explain the present disclosure and should not be interpreted as limiting the present disclosure.

Reference in the description to “one embodiment” or “an example” or “instance” means that a particular feature, structure, or characteristic described in connection with the embodiment itself may be included in at least one embodiment of the patent disclosure. The appearances of the phrase “in one embodiment” in various places of the description are not necessarily all referring to the same embodiment.

Embodiments

As shown inFIG.1, this embodiment provides a method for manufacturing a non-stick pan, which includes the following steps S1to S6:

S1, surface pretreatment. At least two rectangular or square metal sheets1are selected to manufacture a metal composite plate5with a multi-layer composite structure. The number of the metal sheets1may be two, three, four and the like. The metal sheets1may be one or more of stainless steel plates, iron plates, aluminum plates or titanium plates, and the metal sheets1of adjacent layers may be homogeneous metal sheets or heterogeneous metal sheets. The selected metal sheets1are subjected to surface pretreatment. In other words, surfaces of the metal sheets1are cleaned to remove oil stains, oxides and the like on the surfaces of the sheets.

In addition, the selected metal sheets1may have the same size for easy processing. To improve the non-stick performance of the pan made of the metal composite plate5, a titanium plate with excellent performance may be used as an inner layer of the metal composite plate5, while an aluminum plate or a stainless steel plate may be used as an outer layer or an intermediate layer of the metal composite plate5to reduce the production cost.

S2, stacking. The cleaned metal sheets1are stacked one on top of another after the surface pretreatment, and four end corners of each metal sheet1are aligned. To prevent subsequent misalignment of the metal sheets1, the end corners of the metal sheets1may be fixed, for example, by spot welding or the like, to avoid dislocation of the metal sheets1after rolling.

S3, heating. The stacked and aligned metal sheets1are placed into a heating furnace2synchronously through a transmission belt, where a temperature of the heating furnace2is set between 300° C. and 500° C. In this temperature range, most metals such as iron and aluminum are in a softening state and can be easily processed subsequently. It should be noted that the next procedure should be performed within a short time after heating, so as to prevent the metal sheets1from cooling and hardening, which may affect subsequent processing.

S4, rolling. In this embodiment, a knurling machine4with two rollers is used to process the softened metal sheets1, where a pressure of the knurling machine4is set between 100 t and 1000 t. The stacked and aligned metal sheets1are rolled by the rollers, and the heated and softened metal sheets1are compounded into a whole, as shown inFIG.2, to form a metal composite plate5with a first surface51and a second surface52opposite to each other. Meanwhile, at least one roller of the knurling machine4is provided with a concave-convex pattern, and when the metal sheets1are rolled by the roller, as shown inFIG.3, the concave-convex pattern on the roller will be printed on the first surface51or the second surface52of the metal composite plate5to form a concave-convex structure. When a pan is subsequently manufactured, the surface with the concave-convex structure is used as an inner surface of the pan. The knurling procedure is performed simultaneously with the rolling and compounding procedure, thereby reducing the production cost and increasing the efficiency.

In other embodiments, the rolling machine3and the knurling machine4may also be used for processing. Specifically, the metal sheets1arranged in a stack are firstly placed into the rolling machine3for rolling at a pressure between 100 t and 1000 t; and then, the metal composite plate5obtained by rolling and compounding is placed into the knurling machine4for knurling. The knurling machine4is provided with at least one roller with a concave-convex pattern so that the pattern can be printed onto the metal composite plate5. It should be noted that the metal composite plate5is immediately placed into the knurling machine4after being processed by the rolling machine3, so as to prevent the metal composite plate5from being cooled and hardened, which may degrade the pattern processing effect. Specifically, the metal composite plate5passes through the knurling machine4at a temperature controlled between 220° C. and 400° C. In this manner, a uniform heating temperature in the knurling procedure and the rolling procedure is guaranteed, the processed concave-convex pattern is more uniform, and the pattern has a more uniform size, depth, and thickness.

In addition, concave-convex structures may be formed on both the first surface51and the second surface52of the metal composite plate5by simply replacing the roller type used in the patterning tool, which is easy to operate and can save the cost.

S5, annealing. The metal composite plate5is annealed. Preferably, the annealing is performed under a protective reducing atmosphere or in a vacuum environment.

In step S51, the metal composite plate5is made into a roll or cut into webs of desired shapes and sizes. Before annealing, the metal composite plate5may be made into a roll or cut into webs to facilitate subsequent processing or sale. In another embodiment, the step S51may be performed before the step S5, and the metal composite plate5is made into a roll or cut into webs by a user or a manufacturer.

S6, stretching the metal composite plate5into a desired pan shape, and using the surface with the concave-convex structure as an inner layer of the pan. Then, surface micro-arc, sanding, polishing, spraying, handle formation, packaging and other processes are performed on the pan according to the requirements of the pan.

This embodiment further provides a non-stick pan manufactured by the above process steps. The metal composite plate5used has a rectangular configuration, with the concave-convex structure printed on an upper surface and/or lower surface thereof through the process described above. As shown inFIGS.3and4, the concave-convex structure is formed by convex parts53and concave parts54arranged in a staggered manner, and a non-stick coating is sprayed into the concave parts54. Apparently, non-stick coatings formed by other means are also within the protection scope of the present disclosure. The metal composite plate5is stretched into a pan, with the surface with the concave-convex structure as an inner surface of the pan, and since the convex parts53are higher than the concave parts54, a spatula will contact the convex parts53first, thereby avoiding scratching the non-stick coating in the concave parts54and extending the service life of the pan.

In this embodiment, the concave parts54are uniformly or randomly distributed only on the inner surface of the metal composite plate5, and a distance between centers of any two adjacent concave parts54is between 15 μm and 1.5 mm. If the distance between centers of any two adjacent concave parts54is too small, the concave parts54may be arranged too densely to be process easily, and the strength of the inner surface of the pan may be affected; and if the distance between centers of any two adjacent concave parts54is too large, the concave parts54may be arranged too sparsely to store a sufficient amount of oil, and thus the non-stick performance is reduced. In actual use of the pan, on one hand, the concave parts54can absorb air and store grease, and produce hot air and oil mist in the heating process to support food, and on the other hand, the concave parts54can reduce the contact area between the food and the pan, and enhance the physical non-stick function. In other embodiments, the concave-convex structure may be configured into other forms. As shown inFIGS.5and6, bumps are further provided in the concave parts of the concave-convex structure to provide further protection for the non-stick coating.

Compared with the related art in which the concave-convex structure is formed by etching with a chemical agent, the non-etching knurling process in the embodiment is more environment-friendly. Further, the knurling procedure is preposed in the embodiment so that the metal composite plate5does not need to be reheated for knurling. In addition, the annealed metal composite plate5has more stable properties, and can be formed with only wider convex patterns instead of thinner convex patterns even further subjected to heating and knurling, resulting in a subsequent manufactured pan with a poor non-stick effect.

Referring toFIGS.7,8and10, an embodiment further provides a titanium non-stick pan, including a pan body10, where a base material of the pan body10is a metal composite plate with a multi-layer composite structure including a titanium metal layer formed into an inner layer of the pan body. In this embodiment, the titanium metal layer11has a thickness between 0.25 mm and 0.4 mm, and forms a concave-convex structure of a uniform thickness. It should be noted that the uniform thickness here means that the titanium metal layer11has the same thickness throughout the whole range of the concave-convex structure. For example, if the thickness of the titanium metal layer11is 0.3 mm, each part of the concave-convex structure has a thickness of 0.3 mm, so that the problem that the metal layer is thinner at the concave part15formed by etching the inner surface of the pan body10than at the convex part (i.e., the thickness varies at different parts) in the related art is avoided. In this manner, the strength and integrity of the pan body10can be ensured, and the pan body10can be easily stretched into shape during production, thereby improving the yield and quality of the pan body10and reducing the waste of titanium caused by etching.

Referring toFIGS.8and10, the concave-convex structure in the embodiment includes a plurality of interconnected concave-convex unit cells, each of which includes first convex parts14protruding from an inner surface of the pan body10and a concave part15enclosed by the first convex parts14. The concave part15further includes a second convex part16disposed in the concave part15, and the second convex part16has a top lower than each first convex part14. A surface of the titanium metal layer11at the concave-convex structure forms an oxidation layer17with a thickness between 8 μm and 40 μm. When the non-stick pan in this embodiment is used for cooking, the oxidation layer17is in direct contact with food.

In actual use, the concave-convex structure on the inner surface of the pan body10has a non-stick effect, which is specifically and mainly embodied in the following aspects:

1) The non-stick effect can be achieved by the concave-convex structure itself, where the concave-convex structure can reduce the contact area between the inner surface of the pan body10and food, and thereby prevent the food from sticking to the inner surface of the pan body10.

2) By providing the concave part15, oil-water and other mixtures preferably enter the concave part15in cooking, and when the pan body10is heated, high-temperature steam generated by the oil-water can support food from the bottom so that the food is prevented from sticking to the inner surface of the pan body10.

3) The provision of the second convex part16can prevent food of smaller volumes from entering and blocking the concave part15, and since the second convex part16has a height lower than each first convex part14, a two-layer supporting structure can be formed for the food in cooking, so that the food is prevented from sticking to the bottom of the concave part15, thereby improving the non-stick effect. In addition, a concave arcuate structure is further formed between the second convex part16and the first convex part14, and since most food is in special shapes, the arcuate unit cell can be better sealed by the food, so that hot air can be more easily produced on the non-stick layer, and the food can be better supported.

4) An oxidation layer17is provided, especially on the surfaces of the first convex part14, the concave parts15and the second convex part16, where the oxidation layer17in this embodiment is a titanium dioxide layer formed by micro-arc oxidation on the surface of the titanium metal layer11, a structure of a plurality of pores is formed inside the oxidation layer17, and at least part of the pores are communicated with each other. With the structure of the plurality of pores173which may be communicated with each other inside the oxidation layer17, the pores173will absorb oil and water molecules in actual cooking, and the mutually communicated structure can further improve the storage capacity for oil and water molecules. In cooking and heating, the oil-water molecules will be evaporated into gas, so that the amount of evaporated gas is increased, food can be better supported, and a better non-stick effect is achieved.

In the step of performing micro-arc oxidation on the surface of the titanium metal layer11to obtain a titanium dioxide layer, a single pulse current source is used, with a current density being 1.25 to 1.6A/dm2, a duty cycle being 12% to 15%, and a frequency being 500 Hz.

It can be seen that, in this embodiment, the inner layer of the pan body10is configured as a titanium metal layer11, which can reduce the weight of the pan body10and improve the strength and corrosion resistance of the pan body10; and a concave-convex structure is provided on the titanium metal layer11to improve the non-stick effect of the inner surface of the pan body10(through the various structures for improving the non-stick effect described above). In addition, the concave-convex structure on the titanium metal layer11has a uniform thickness, which is different from the processing method in the related art having the problems of waste of titanium and reduced strength of the pan body10caused by removing materials of the pan body10by an etching. In actual settings, the thickness of the titanium metal layer11in the present disclosure is only 0.25 mm to 0.4 mm, which reduces the titanium consumption by at least 12.5% to 37.5% compared with a titanium non-stick pan processed by the conventional etching method (where the titanium metal layer11has a thickness of at least 0.4 mm).

It should be noted that the concave-convex structure in the present disclosure may cover the whole inner surface of the pan body10, or may be provided partially on the inner surface of the pan body10.

Referring toFIG.11, an oxidation layer17according to one embodiment of the present disclosure includes a first oxidation layer171formed on bottom and side surfaces of the concave part15and top and side surfaces of the second convex part16, and a second oxidation layer172formed on top surfaces of the first convex parts14. The first oxidation layer171has a thickness between 20 μm and 40 μm, and the second oxidation layer172has a thickness between 8 μm and 20 μm. After the inner surface of the pan body10is oxidized, an inner wall of the pan body10is typically polished to remove impurities formed on the inner surface of the pan body10during the oxidation process and improve the surface quality of the pan body10. The polishing process may reduce the thickness of the oxidation layer on the top surfaces of the first convex parts14to a certain extent, but since the oxidation layer subjected to micro-arc oxidation is relatively thick, the second oxidation layer172of a certain thickness (8 to 20 μm) will still exist on the top surfaces of the first convex parts14after polishing in the actual production. In addition, in the polishing process, due to the presence of the first convex parts14, the surfaces of the concave part15and the second convex part16will not be polished. In this case, the first oxidation layer171on the surfaces of the concave part15and the second convex part16is thicker, which can produce a better non-stick effect, and since the concave part15is a region that provides the majority of the non-stick effect, the whole pan body10can achieve a better non-stick effect.

Referring toFIG.9, in one embodiment of the present disclosure, the first convex parts14are each set to have a width L2=0.2 mm to 0.5 mm, and a height H1=0.08 mm to 0.25 mm. A distance between two points of each first convex part14opposite to each other with respect to a center of the concave part15is L1=2.5 mm to 3.5 mm. In actual settings, the concave part15enclosed by the first convex parts14is shaped into a circle or a regular polygon (generally a regular hexagon). When the concave part15has a circular shape, a diameter of the concave part15is set to 2.5 mm to 3.5 mm; when the concave part15has a regular hexagon shape, a spacing between two opposite lines of the concave part15is set to 2.5 mm to 3.5 mm.

The oxidation layer17in the present disclosure is formed by micro-arc oxidation on the titanium metal layer11, a structure of a plurality of pores173is formed inside the oxidation layer17, and at least part of the pores173are communicated with each other. Compared with an oxide film formed by titanium anodic oxidation, the titanium dioxide oxidation (TiO2) layer17formed by micro-arc oxidation on the titanium metal layer11is thicker, and has a higher rate of pores173, higher roughness, and better insulation of film layers. In addition, since the micro-arc oxidation process generally uses higher voltage and current, where the voltage is generally higher than 500V, and processing is performed in a circulated manner with a solution in production, there is no emission and pollution, and a titanium oxidation layer with a hardness up to HV500 to 600, as well as better wear resistance and corrosion resistance, can be obtained.

In contrast, the oxidation film layer produced by titanium anodic oxidation is more compact and thinner (with a thickness of only 0.5 μm to 2 μm), and the voltage and current densities used in the anodic oxidation are relatively low (with a voltage generally between 15V and 100V), so the resulted oxidation film has very low hardness and wear resistance, and generates pollution and emission in the process since the oxidation film is typically manufactured into oxidation film layers for an attractive appearance of the pan body10. Although theoretically, the thickness of a common titanium anodic oxidated film can reach 10 μm to 20 μm, a long-time oxidation process is required to reach such a thickness, resulting in a low efficiency. Such an anodic oxidated film has compact film layers, and involves a great amount of time and cost to increase the thickness of the oxidation film, which has no contribution to improving the non-stick function. Therefore, in the related art, the surface of the pan is generally processed into a rough surface, and then anodic oxidation is performed on the rough surface to achieve certain non-stick property. Since the resulted anodic oxidated film is thinner (generally with a thickness of only 0.5 μm to 2 μm), when the inner surface of the pan body10is polished after oxidation, the anodic oxidated film on the surfaces of the first convex parts14will be directly eliminated to expose the base metal material, making food easy to stick to the pan in cooking due to direct contact with the base metal material. If not polished, however, the surface quality of the pan body10will be affected.

The oxide film obtained by micro-arc oxidation has a higher rate of pores173and a higher roughness, so that the surface of the base material does not need to be roughened in advance. Referring toFIGS.13and8, the oxidation layer17formed by micro-arc oxidation is thicker, and has intricate pores173inside, and the pores may be further communicated with each other, so that the oxidation layer17can store more oil molecules. In cooking and heating, air in the pores173are thermally expanded to evaporate the stored oil molecules into oil gas, so that the food can be better supported and better non-stick performance is achieved. Meanwhile, since the oxidation layer17obtained by micro-arc oxidation is thicker, the film layer on the top surfaces of the first convex parts14can still have a thickness of 8 μm to 20 μm (not less than the thickness of the oxidation layer17produced by anodic oxidation) after being polished for attractive reasons, so that a better non-stick effect can be achieved in cooperation with the thicker (20 μm to 40 μm) oxidation layer17on the surfaces of the concave part15and the second convex part16.

In the titanium non-stick pan of the present disclosure, the concave part15plays a main role in the non-stick effect, and therefore, the areas of the concave part15and the first convex part14of the non-stick pan have to satisfy certain proportions to ensure a better non-stick effect. In one embodiment of the present disclosure, the first convex parts14take a proportion less than 20% relative to a total area of the concave-convex structure, and the concave part15takes a proportion not less than 80% relative to the total area of the concave-convex structure. The proportions of the first convex part14and the concave part15are controlled so that the area of the concave part15, i.e., the region providing the majority of the non-stick effect, is ensured, thereby improving the non-stick effect. In actual design, the proportion of the first convex part14in the total area of the concave-convex structure can be comprehensively controlled by controlling the width and distribution density of the first convex part14.

Referring toFIGS.8,9,10,11and12, in one embodiment of the present disclosure, the second convex part16is disposed at a central position of the concave part15, and has a diameter between 0.15 mm and 0.2 mm and a height lower than each first convex part14by H1−H2=0.05 mm to 0.1 mm. Since the second convex part16has a height lower than each first convex part14, the surface of the second convex part16will not be polished when the inner surface of the pan body10is polished, so that the oxidation layer17on the surfaces of the second concave part16and the concave part15can be reserved with a complete thickness, where only the oxidation layer17on the top surfaces of the first convex parts14is partially polished off to improve the surface quality of the pan body10. In addition, it should be noted that due to the presence of the second convex part16, a concave arcuate structure is formed between the second convex part16and the first convex part14, which further helps to lift the food and improve the non-stick effect. Apparently, the embodiment in which the second convex part16is disposed at a central position of the concave part15is a preferred embodiment of the present disclosure, where the second convex part16has the same distance to peripheries of the corresponding first convex parts14, so that the overall appearance and textured feeling of the pan body10can be improved. In actual settings, the second convex part16may be arranged at a position deviated from the center of the concave part15, and more than one second convex part16may be provided in the convex part15. It should be noted that, when more than one second convex parts16are provided in the convex part15, the area of the concave part15may be appropriately increased, which is equivalent to reducing the area proportion of the corresponding first convex parts14, and can also achieve a good non-stick effect.

In the present disclosure, the multi-layer composite structure of the pan body10may be a titanium-aluminum composite double-layer metal structure, and in this case, a titanium metal layer forms an inner layer of the pan body10, and an aluminum layer forms an outer layer of the pan body10; or, the multi-layer composite structure of the pan body10may be a titanium-aluminum-steel composite three-layer metal structure, and in this case, the base metal layer12is located between a titanium metal layer11and a steel metal layer13, and the metal layers of the pan body10from outside to inside are steel, aluminum and titanium in sequence.

In manufacture of the pan body10according to the present disclosure, the multiple layers of metal sheets in the composite structure are formed by hot-pressing and compounding, and in the hot-pressing and compounding process, larger metal sheets may be continuously rolled into a plurality of composite metal sheets in accordance with the size of the pan body10. Since the concave-convex structure is directly pressed in the compounding process, the titanium metal layer11on the inner surface of the pan body10has a uniform thickness (i.e., various parts of the concave-convex structure have the same thickness) despite the first convex part14and the concave part15on the inner surface of the pan body10. In addition, since aluminum is softer than titanium, the titanium metal layer11is plastically deformed under a pressure during rolling, and the base metal layer12is also deformed accordingly. Before rolling, projections are formed on a surface of the base metal layer12, and in the rolling process of the base metal layer12and the titanium metal layer11, the projections on the surface of the base metal layer12form a mortise and tenon joint structure nested with each other with the concave-convex structure of the titanium metal layer11. Referring toFIGS.11and6, in this manner, a better bonding force can be achieved between the two metals, the overall effect of the pan body10can be improved, and the titanium consumption can be reduced. The metal sheet formed in this way can use a thinner titanium metal layer11. In other words, the formed pan has a pattern of a concave-convex structure on the inner surface, a nested structure in the middle, and a back surface freely selected as a surface with a pattern or a flat surface.

Referring toFIG.11, in the present disclosure, the top surfaces of the first convex part14and the second convex part16in the concave-convex structure may be configured as planar structures. In one embodiment of the present disclosure, tops of each first convex part14and/or the second convex part16are configured as pointed ends, as shown inFIG.12. By providing the tops of the first convex part14and the second convex part16both as pointed ends, the contact area between the food and the pan body10is smaller in cooking (compared with the case where the tops of the first convex part14and the second convex part16are both planar structures), and a better non-stick effect can be achieved. Further, it is conceivable that, in actual design, the tops of the first convex part14and the second convex part16may be both configured as planar structures or pointed end, or one may be configured as a planar structure and the other as a pointed end. It should be noted that, when the tops of the first convex part14and the second convex part16are both configured as pointed ends, the width of each first convex part14or second convex part16refers to a width at a root portion of the part.

Apparently, the pan body10of the present disclosure may be further provided with a handle18, where the handle18is made of wood or rubber or any other material with poor thermal conductivity, and detachably connected to the pan body10. A flange19may be further provided at an opening edge of the pan body10to improve the overall appearance of the pan, enhances the strength of the pan body10, and improves safety (avoiding scalding, scratching and the like) in use.

Table 1 shows parameters of titanium non-stick pans according to three different embodiments of the present disclosure, and parameters of a titanium pan in a comparative example.

TABLE 1Thickness ofThicknessoxidation layerof titaniumCurrentDutyat concave-metaldensitycycleFrequencyconvexNo.layer(A/dm2)(%)(Hz)structureEmbodiment 10.25 mm1.251250040 μmEmbodiment 20.4 mm1.42513.550020 μmEmbodiment 30.3 mm1.6155008 μmComparative0.15 mm———30 μmexample

It should be noted that the oxide layers in embodiments 1 to 3 are formed by micro-arc oxidation, while the oxidation layer of the titanium pan in the comparative example is formed by anodic oxidation.

Test Example

A pan is placed on a gas stove and heated for 2 min, and then a raw egg is added into the pan.FIG.15shows the effect of the titanium non-stick pan in embodiment 1;FIG.16shows the effect of the titanium non-stick pan in embodiment 2;FIG.17shows the effect of the titanium non-stick pan in embodiment 3; andFIG.18shows the effect of the titanium pan in the comparative example.

As can be seen fromFIGS.15to18, the titanium non-stick pans of embodiments 1 to 3 have less food residue and better non-stick performance, while the titanium non-stick pan of the comparative example has more food residue and poorer non-stick performance.

The above are merely specific implementations of the present disclosure, and the protection scope of the present disclosure is not limited thereto, and it will be understood by those skilled in the art that the present disclosure includes, but is not limited to, the contents given in the drawings and the description of the specific implementations. Any modifications which do not depart from the functional and structural principles of the present disclosure are intended to be included within the scope of the claims.