Enamel porcelain double-layer vacuum cup and manufacturing method thereof

Abstract

The invention provides an enamel porcelain double-layer vacuum insulation cup and a manufacturing method thereof.The enamel porcelain double-layer vacuum insulation cup comprises an inner container, an outer container and an outer container bottom cover, the top opening ends of the inner container and the outer container are connected in a welded mode, a vacuum layer is formed between the inner container and the outer container, the outer container bottom cover is connected with the bottom of the outer container in a welded mode, and the outer container bottom cover is connected with the bottom of the outer container in a welded mode. An exhaust hole is formed in the outer container bottom cover, the inner wall of the inner container and the outer wall of the outer container are both coated with enamel porcelain coatings, and the joint of the top opening ends of the inner container and the outer container is coated with an enamel porcelain coating. According to the manufacturing method, a low-temperature vacuum welding technology is adopted, so that the influence of a high-temperature environment on the light-color enamel porcelain coating on the outer wall of the vacuum cup is avoided, and the requirements of customers on the light-color enamel porcelain double-layer vacuum cup are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat preservation cups, and particularly relates to an enamel double-layer vacuum heat preservation cup and a manufacturing method thereof. Background Art

[0002] As an energy-efficient heat preservation container, the double-layer vacuum heat preservation cup is widely used in daily life and various outdoor activities. Its basic principle is to form a vacuum heat insulation layer between the double-layer metal structures, thereby effectively blocking heat transfer and achieving a long-term heat preservation effect. With the improvement of consumers' pursuit of product quality and aesthetics, enamel has gradually been applied to the field of heat preservation cup manufacturing. Enamel can endow the heat preservation cup with better color, and at the same time, enamel has a hard texture, good wear resistance and corrosion resistance. Coated on the cup wall of the heat preservation cup, it can significantly improve the durability of the heat preservation cup and effectively extend the service life of the product. Moreover, its smooth and delicate surface is easy to clean and maintain, and can always keep the sanitary condition of the heat preservation cup, providing many conveniences for users.

[0003] Chinese Patent Application No. 2019111864433 discloses a double-layer vacuum heat preservation container, which coats enamel coatings on the inner and outer walls of the inner liner and the inner wall of the outer liner, effectively reducing the entry of gas into the heat insulation space and improving the heat preservation effect.

[0004] In the existing production process, it is necessary to place the assembled double-layer heat preservation cup in a high-temperature vacuum device, and use the high-temperature vacuum environment to form a vacuum layer between the inner liner and the outer liner of the heat preservation cup. For heat preservation cups made of dark enamel materials, even after such a high-temperature vacuum processing process, it seems difficult to detect obvious defects by direct visual observation. This is mainly because the dark enamel itself has a relatively deep color, which can cover up the subtle changes that may be caused by high temperature to a certain extent, such as slight color deviation and extremely fine texture changes on the glaze surface. However, when light-colored enamel heat preservation cups are faced with the same high-temperature vacuum environment, the situation is quite different. Light-colored enamel has a light color and a relatively more delicate and sensitive texture, and the high-temperature environment is likely to cause the internal metal substrate (such as stainless steel) to release trace amounts of metal vapor, which physically adsorbs or chemically reacts with the enamel glaze surface, thereby significantly changing its original pure color and showing color differences such as yellowing and graying. Moreover, high temperature may also cause tiny bubbles, cracks or roughness on the glaze surface (coating) of light-colored enamel, and these defects are particularly prominent against the background of the light-colored background, greatly affecting the appearance quality and visual effect of the product and resulting in a very low qualified rate. Summary of the Invention

[0005] The present invention provides an enamel porcelain double-layer vacuum heat-insulating cup and a manufacturing method thereof. By adopting a low-temperature vacuum welding technology, the influence of high-temperature environment on the light-colored enamel porcelain coating on the outer wall of the heat-insulating cup is avoided, meeting the needs of customers for light-colored enamel porcelain double-layer vacuum heat-insulating cups.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A manufacturing method of an enamel porcelain double-layer vacuum heat-insulating cup, comprising the following technological steps carried out in sequence:

[0008] S1: Process the pipe into the shapes of the required inner container and outer container, press the inner container into the outer container, and then connect the open ends of the inner container and the outer container together through a welding process;

[0009] S2: Coat the inner container and the outer container with enamel porcelain glaze, and then put them into a high-temperature furnace for firing to form an enamel porcelain coating;

[0010] S3: Process exhaust holes on the bottom cover of the outer container, adhere a suction sheet to the bottom cover of the outer container, and then weld the bottom cover of the outer container to the bottom of the outer container, while ensuring that the suction sheet is located between the inner container and the outer container;

[0011] S4: Place the semi-finished heat-insulating cup in a device adopting a low-temperature vacuum sealing process, evacuate the gas impurities between the inner container and the outer container through the exhaust holes to form a vacuum layer, and then use the sealing means in the low-temperature vacuum sealing process to block the exhaust holes in the device;

[0012] S5: Place the heat-insulating cup on a heating device, and heat the bottom cover of the outer container by local heating to activate the suction sheet;

[0013] S6: Bond a silica gel anti-slip pad to the bottom of the outer container.

[0014] To form a vacuum layer in a traditional double - wall vacuum insulated cup, the insulated cup needs to be placed in a high - temperature vacuum device. However, such a high - temperature environment can cause surface defects on the enamel porcelain, such as cracks, dirt, or color differences. Therefore, in existing enamel porcelain double - wall vacuum insulated cups, the enamel porcelain is not coated on the outer wall of the insulated cup. For those technicians who wish to produce insulated cups with an enamel porcelain coating on the outer wall, they usually can only choose dark - colored enamel porcelain to partially cover these surface defects, but this still cannot meet the needs of users who like light - colored enamel porcelain insulated cups. To coat the outer wall of the insulated cup with a light - colored enamel porcelain coating, the common approach that those skilled in the art would think of is to first complete the manufacture of a traditional vacuum insulated cup, then coat the outer surface with enamel porcelain glaze, and then put it into a high - temperature furnace for firing. However, this method easily causes the formed vacuum layer to be damaged at high temperatures, greatly reducing the heat - preservation effect of the insulated cup. Another attempt is to use a later manual repair method to cover the defects on the enamel porcelain coating, but this method has a high cost and it is difficult to guarantee the appearance and quality of the product.

[0015] Therefore, to address the above problems, the present invention adopts a non - traditional manufacturing method to produce an enamel porcelain double - wall vacuum insulated cup. This method can effectively avoid the generation of surface defects on the enamel porcelain, thereby meeting the production requirements of light - colored enamel porcelain insulated cups.

[0016] In the manufacturing method of the present invention, the vacuum layer of the double - wall vacuum insulated cup is formed in a low - temperature environment. This can avoid the influence of the high - temperature environment on the formed enamel porcelain coating, ensure the color of the enamel porcelain coating, and avoid the formation of surface defects such as stains, micro - bubbles, or cracks. It is worth mentioning that the traditional way to form a vacuum layer is to place a glass - based brazing flux on the small hole at the bottom of the outer liner, then evacuate the gas between the inner and outer liners in a high - temperature vacuum environment, and let the glass - based brazing flux melt to block the small hole. In the solution of the present invention, a low - temperature vacuum sealing technology is adopted. The gas impurities between the inner and outer liners are evacuated through the exhaust hole to form a vacuum layer, and finally the exhaust hole is blocked, and during this process, there is no contact with the enamel porcelain coating. In this way, the adverse effect of high temperature on the enamel porcelain coating is effectively avoided, meeting the production requirements of light - colored enamel porcelain double - wall vacuum insulated cups. In addition, the getter in the vacuum layer is also activated by locally heating the bottom cover of the outer liner, rather than in a high - temperature environment for the whole insulated cup. This also avoids the influence of the high - temperature environment on the enamel porcelain coating, further ensuring the quality and appearance of the product.

[0017] Preferably, in the step S3, a plurality of exhaust holes are provided, and the plurality of exhaust holes are evenly spaced. By providing a plurality of exhaust holes, gas impurities between the inner liner and the outer liner can be discharged more quickly and evenly, the vacuum pumping time can be shortened, and the production efficiency can be improved. Moreover, the exhaust holes evenly spaced make the gas discharge rate in each area between the inner liner and the outer liner tend to be consistent, avoiding the problem of uneven vacuum degree caused by poor local air extraction; this ensures the stable quality of the entire vacuum layer and makes the heat preservation effect of the thermos cup more balanced in each part.

[0018] Preferably, the exhaust holes are circular or rectangular. Exhaust holes of both shapes can effectively discharge gas impurities. The rectangular exhaust holes can provide a larger exhaust area and can discharge gas more quickly, further shortening the vacuum pumping time; while the circular exhaust holes are easier to be sealed by welding or other means, improving the production efficiency. Producers can choose the shape of the exhaust holes according to the actual production situation.

[0019] Preferably, in the step S4, the equipment adopting the low-temperature vacuum sealing process is a low-temperature vacuum welding equipment, the welding temperature is 150 - 300 °C, and the vacuum degree ≤ 10 -4 Pa. The reason for preferentially adopting low-temperature vacuum welding instead of low-temperature vacuum glue sealing or other methods is that welding can achieve the fusion of metal materials at the atomic level, and there are almost no gaps for gas leakage, thus ensuring the extremely reliable sealing performance of the vacuum layer; moreover, the method of glue sealing may require additional time and processes to complete the same task, increasing the production complexity and cost, but the low-temperature vacuum welding equipment can complete the vacuum pumping and sealing processes in one operation, simplifying the production process flow. It is worth mentioning that the vacuum degree ≤ 10 -4 Pa enables a good vacuum layer to be formed between the inner liner and the outer liner. Controlling the welding temperature at 150 - 300 °C can not only ensure that the welding material can be fully melted and seal the exhaust holes, but also effectively avoid the adverse effects of high temperature on the enamel porcelain coating. Importantly, a getter (such as a titanium-based getter) is adhered to the bottom cover of the outer liner, and its activation temperature is usually above 400 °C; within the welding temperature range (150 - 300 °C) of the step S4, the getter will not be activated, thus ensuring its normal function in the subsequent step S5. This phased process design not only protects the performance of the getter, but also avoids the problem of the decline in the performance of the vacuum layer caused by premature activation.

[0020] Preferably, in the step S5, the heating device is an electric furnace, and the local heating method is to only make the bottom cover of the outer container contact the heating area of the electric furnace. By adopting the local heating method of only making the bottom cover of the outer container contact the heating area of the electric furnace, the heat can be accurately transferred to the suction sheet on the bottom cover of the outer container. Since the suction sheet usually has specific requirements for the activation temperature, this accurate heating method can ensure that the suction sheet is activated at an appropriate temperature, giving full play to its role of absorbing the residual gas in the vacuum layer and maintaining the vacuum degree. Compared with the overall heating method, it can more effectively avoid the situation that the suction sheet is not fully activated or its performance is damaged due to overheating or insufficient heating, greatly improving the activation effect of the suction sheet. Importantly, during the activation of the suction sheet, only the bottom cover of the outer container is locally heated, which can minimize the thermal impact on other parts of the thermos cup, especially the parts with enamel porcelain coating. This local heating method can effectively prevent the whole thermos cup from being in a high-temperature environment, ensuring the integrity, beauty and protective performance of the coating are not damaged.

[0021] Preferably, the temperature of the heating area of the electric furnace is 700 - 900 °C, and the heating time is 3 - 20 min. In this way, it can ensure that the suction sheet is fully activated, enabling it to quickly adsorb the trace gas remaining in the vacuum layer in a short time, effectively improving the purity of the vacuum layer, and further optimizing the heat preservation performance of the thermos cup.

[0022] Preferably, in the step S2, it further includes: before coating the enamel porcelain glaze, the inner container and the outer container are first subjected to surface sandblasting treatment. Through the surface sandblasting treatment, a microscopic rough surface is formed on the inner container and the outer container, significantly improving the adhesion between the enamel porcelain coating and the metal substrate.

[0023] In addition, the present invention also provides an enamel porcelain double-layer vacuum thermos cup, including an inner container, an outer container and a bottom cover of the outer container. The top open ends of the inner container and the outer container are connected by welding. A vacuum layer is formed between the inner container and the outer container. The bottom cover of the outer container is connected to the bottom of the outer container by welding. An exhaust hole is provided on the bottom cover of the outer container. Enamel porcelain coatings are applied to the inner wall of the inner container and the outer wall of the outer container. An enamel porcelain coating is applied to the connection part of the top open ends of the inner container and the outer container.

[0024] Some existing enamel porcelain vacuum cups can only coat the enamel porcelain coating on the inner wall of the inner liner due to manufacturing process problems. It is difficult to make the same treatment on the outer wall of the outer liner, resulting in the outer liner being easily scratched, oxidized, etc., affecting the appearance and service life. The enamel porcelain double-layer vacuum cup in the present invention not only coats the enamel porcelain coating on the inner wall of the inner liner, but also coats the enamel porcelain coating on the outer wall of the outer liner and the connection of the top opening ends of the inner liner and the outer liner. This comprehensive coating design not only improves the beauty of the vacuum cup, but also provides effective protection for the outer liner, preventing the outer liner from rusting and scratching. Moreover, the enamel porcelain coating makes stains not easy to adhere, and the cleaning is more convenient and fast. It is worth mentioning that the connection between the inner liner and the outer liner of the existing products is usually not specially treated, which is easy to accumulate dirt or corrode. In the present invention, the enamel porcelain coating is also coated on the connection of the top opening ends of the inner liner and the outer liner. The enamel porcelain coating tightly covers the connection, filling the possible fine gaps, thereby enhancing the sealing performance; at the same time, the smooth surface of the coating makes the connection easier to clean, greatly improving the overall durability of the vacuum cup. Among them, the enamel porcelain coating can be light-colored.

[0025] Importantly, the exhaust hole provided on the bottom cover of the outer liner plays a key role in the manufacturing process. By providing an exhaust hole on the bottom cover of the outer liner, the gas impurities between the inner liner and the outer liner can be evacuated by a low-temperature vacuum welding device and then the exhaust hole can be sealed, so as to finally form a good vacuum layer, avoiding the influence of high temperature on the formed enamel porcelain coating and ensuring the color and quality of the coating.

[0026] Preferably, the outer wall of the inner liner and the inner wall of the outer liner are both coated with an enamel porcelain coating. In fact, during the production process of the high-temperature forming of the enamel porcelain coating, an oxide layer is easily formed on the outer wall of the inner liner and the inner wall of the outer liner, and the oxide layer is easy to adsorb gas and water vapor. This leads to that during the vacuum pumping process, the gas and water vapor adsorbed by the oxide layer will be released to a certain extent, resulting in difficulty in achieving an ideal vacuum state. Even if a relatively high vacuum degree is achieved in a short time, over time, these adsorbed substances may gradually escape, damaging the vacuum environment. Therefore, coating the enamel porcelain coating on the outer wall of the inner liner and the inner wall of the outer liner can avoid the generation of the oxide layer and ensure the formation quality of the vacuum layer. In addition, the enamel porcelain material itself has a relatively low thermal conductivity, so coating the enamel porcelain coating on the outer wall of the inner liner and the inner wall of the outer liner can, to a certain extent, serve as an additional heat insulation layer to reduce heat dissipation.

[0027] Preferably, the thickness of the enamel porcelain coating is 0.1 mm - 0.5 mm. By controlling the thickness of the enamel porcelain coating between 0.1 mm and 0.5 mm, it can be ensured that the coating is thick enough to provide effective protection against scratches, corrosion, etc. of the inner liner and the outer liner, and at the same time, it will not be too thick to cause an increase in brittleness or affect the stability of the overall structure. This thickness range can balance hardness and flexibility and extend the service life of the vacuum cup.

[0028] In summary, for such an enamel double - wall vacuum thermos cup and its manufacturing method, by adopting the low - temperature vacuum welding technology, the influence of high - temperature environment on the light - colored enamel coating on the outer wall of the thermos cup is avoided, meeting the needs of customers for light - colored enamel double - wall vacuum thermos cups. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of the enamel double - wall vacuum thermos cup in the present invention.

[0031] In the figure, 1 - outer liner; 2 - bottom cover of the outer liner; 3 - exhaust hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following further explains the specific embodiments of the present invention with reference to the drawings. It should be noted here that the description of these embodiments is for helping to understand the present invention, but does not limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] A manufacturing method of an enamel double - wall vacuum thermos cup includes the following technological steps in sequence:

[0034] S1: Process the pipe material into the shapes of the required inner liner and outer liner 1, press the inner liner into the outer liner 1, and then connect the open ends of the inner liner and the outer liner 1 through the welding process;

[0035] S2: Coat the inner liner and the outer liner 1 with enamel glaze, and then put them into a high - temperature furnace for firing to form an enamel coating;

[0036] S3: Process an exhaust hole 3 on the bottom cover 2 of the outer liner, adhere a suction sheet to the bottom cover 2 of the outer liner, and then weld the bottom cover 2 of the outer liner to the bottom of the outer liner 1, while ensuring that the suction sheet is located between the inner liner and the outer liner 1;

[0037] S4: Place the semi - finished thermos cup in a device adopting the low - temperature vacuum sealing process, evacuate the gas impurities between the inner liner and the outer liner 1 through the exhaust hole 3 to form a vacuum layer, and then use the sealing means in the low - temperature vacuum sealing process to block the exhaust hole 3 in the device;

[0038] S5: Place the vacuum flask on a heating device and heat the bottom cover 2 of the outer container by local heating to activate the getter sheet;

[0039] S6: Bond the silica gel anti-slip pad to the bottom of the outer container 1.

[0040] For a traditional double-layer vacuum flask to form a vacuum layer, the vacuum flask needs to be placed in a high-temperature vacuum device. However, such a high-temperature environment may cause surface defects such as cracks, dirt, or color differences on the surface of the enamel porcelain. Therefore, in existing enamel porcelain double-layer vacuum flasks, the enamel porcelain is not coated on the outer wall of the vacuum flask. For those technicians who wish to produce vacuum flasks with an enamel porcelain coating on the outer wall, they usually can only choose dark enamel porcelain to partially cover these surface defects, but this still cannot meet the needs of users who like light-colored enamel porcelain vacuum flasks. To coat the outer wall of the vacuum flask with a light-colored enamel porcelain coating, the common treatment method that technicians in this field would think of is to first complete the manufacture of a traditional vacuum flask, then coat the outer surface with enamel porcelain glaze, and then place it in a high-temperature furnace for firing. However, this method is likely to cause the formed vacuum layer to be damaged at high temperatures, greatly reducing the heat preservation effect of the vacuum flask. Another attempt is to use a post-handicraft repair method to cover the defects on the enamel porcelain coating, but this method has a high cost, and the appearance and quality of the product are difficult to guarantee.

[0041] Therefore, to address the above problems, the present invention adopts a non-traditional manufacturing method to produce an enamel porcelain double-layer vacuum flask, which can effectively avoid the generation of surface defects on the enamel porcelain, thereby meeting the production requirements of light-colored enamel porcelain vacuum flasks.

[0042] In the manufacturing method of the present invention, the vacuum layer of the double-layer vacuum flask is formed in a low-temperature environment, which can avoid the influence of the high-temperature environment on the formed enamel porcelain coating, ensure the color of the enamel porcelain coating, and avoid the formation of surface defects such as stains, micro-bubbles, or cracks.

[0043] It is worth mentioning that the traditional method of forming a vacuum layer is to place a glass-based brazing flux on the small holes at the bottom of the outer container 1, then evacuate the gas between the inner and outer containers 1 in a high-temperature vacuum environment, and let the glass-based brazing flux melt to block the small holes. In the solution of the present invention, a low-temperature vacuum sealing technology is adopted. The gas impurities between the inner and outer containers 1 are evacuated through the exhaust hole 3 to form a vacuum layer, and finally the exhaust hole 3 is blocked, and the enamel porcelain coating will not be affected during this process. In this way, the adverse effect of high temperature on the enamel porcelain coating is effectively avoided, meeting the production requirements of light-colored enamel porcelain double-layer vacuum flasks. In addition, the getter sheet located in the vacuum layer is also activated by locally heating the bottom cover 2 of the outer container, rather than in a high-temperature environment for the entire vacuum flask, which also avoids the influence of the high-temperature environment on the enamel porcelain coating and further ensures the quality and appearance of the product.

[0044] In addition, in step S3, a plurality of exhaust holes 3 are provided, and the plurality of exhaust holes 3 are evenly spaced. By providing a plurality of exhaust holes 3, gas impurities between the inner container and the outer container 1 can be discharged more quickly and evenly, shortening the vacuum pumping time and improving production efficiency. Moreover, the exhaust holes 3 evenly spaced ensure that the gas discharge rates in various regions between the inner container and the outer container 1 tend to be consistent, avoiding the problem of uneven vacuum degree caused by poor local air extraction; this ensures the stable quality of the entire vacuum layer and makes the heat preservation effect of the thermos cup more balanced in each part.

[0045] Among them, the exhaust hole 3 is circular or rectangular. Exhaust holes 3 of both shapes can effectively discharge gas impurities. The rectangular exhaust hole 3 can provide a larger exhaust area and can discharge gas more quickly, further shortening the vacuum pumping time; while the circular exhaust hole 3 is easier to be sealed by welding or other means, improving production efficiency. Producers can choose the shape of the exhaust hole 3 according to the actual production situation.

[0046] In addition, in step S4, the equipment adopting the low-temperature vacuum sealing process is a low-temperature vacuum welding equipment, the welding temperature is 150 - 300 °C, and the vacuum degree ≤ 10 -4 Pa. The reason for preferentially using low-temperature vacuum welding instead of low-temperature vacuum adhesive sealing or other methods is that welding can achieve fusion of metal materials at the atomic level, and there are almost no gaps for gas leakage, thus ensuring extremely reliable sealing of the vacuum layer; moreover, the method of adhesive sealing may require additional time and processes to complete the same task, increasing production complexity and cost, but the low-temperature vacuum welding equipment can complete the vacuum pumping and sealing processes in one operation, simplifying the production process flow.

[0047] It is worth mentioning that the vacuum degree ≤ 10 -4 Pa enables a good vacuum layer to be formed between the inner container and the outer container 1. Controlling the welding temperature at 150 - 300 °C can not only ensure that the welding material can be fully melted and seal the exhaust hole 3, but also effectively avoid the adverse effects of high temperature on the enamel porcelain coating. Importantly, a getter (such as a titanium-based getter) is adhered to the bottom cover 2 of the outer container, and its activation temperature is usually above 400 °C; within the welding temperature range (150 - 300 °C) of step S4, the getter will not be activated, thus ensuring its normal function in the subsequent step S5. This phased process design not only protects the performance of the getter, but also avoids the problem of degradation of the vacuum layer performance caused by premature activation.

[0048] In addition, in step S5, the heating device is an electric furnace, and the local heating method is to only make the outer tank bottom cover 2 contact the heating area of the electric furnace. By adopting the local heating method of only making the outer tank bottom cover 2 contact the heating area of the electric furnace, heat can be accurately transferred to the getter on the outer tank bottom cover 2. Since the getter usually has specific requirements for the activation temperature, this precise heating method can ensure that the getter is activated at an appropriate temperature, giving full play to its role in absorbing the residual gas in the vacuum layer and maintaining the vacuum degree. Compared with the overall heating method, it can more effectively avoid the situation where the getter is not fully activated or its performance is damaged due to overheating or insufficient heating, greatly improving the activation effect of the getter. Importantly, during the activation of the getter, only the outer tank bottom cover 2 is locally heated, which can minimize the thermal impact on other parts of the thermos cup, especially the parts with enamel porcelain coating. This local heating method can effectively prevent the whole thermos cup from being in a high-temperature environment, ensuring the integrity, aesthetics and protective performance of the coating are not damaged.

[0049] In addition, the temperature of the heating area of the electric furnace is 700 - 900 °C, and the heating time is 3 - 20 min. In this way, it can ensure that the getter is fully activated, enabling it to quickly adsorb the trace gas remaining in the vacuum layer in a short time, effectively improving the purity of the vacuum layer, and further optimizing the heat preservation performance of the thermos cup.

[0050] In addition, step S2 further includes: before applying the enamel porcelain glaze, the inner tank and the outer tank 1 are first subjected to surface sandblasting treatment. Through the surface sandblasting treatment, a microscopically rough surface is formed on the inner tank and the outer tank 1, significantly improving the adhesion of the enamel porcelain coating to the metal substrate.

[0051] Refer to Figure 1 As shown, the present invention also provides an enamel porcelain double-layer vacuum thermos cup, including an inner tank, an outer tank 1 and an outer tank bottom cover 2. The top open end of the inner tank and the outer tank 1 is connected by welding. A vacuum layer is formed between the inner tank and the outer tank 1. The outer tank bottom cover 2 is connected to the bottom of the outer tank 1 by welding. An exhaust hole 3 is provided on the outer tank bottom cover 2. Enamel porcelain coatings are applied on the inner wall of the inner tank and the outer wall of the outer tank 1, and an enamel porcelain coating is also applied at the connection of the top open end of the inner tank and the outer tank 1.

[0052] Some existing enamel porcelain thermos cups can only apply the enamel porcelain coating on the inner wall of the inner tank due to manufacturing process problems. It is difficult to make the same treatment on the outer wall of the outer tank 1, resulting in the outer tank 1 being easily scratched, oxidized, etc., affecting the appearance and service life. In the enamel porcelain double-layer vacuum thermos cup of the present invention, not only the inner wall of the inner tank is coated with an enamel porcelain coating, but also the outer wall of the outer tank 1 and the connection of the top open end of the inner tank and the outer tank 1 are coated with enamel porcelain coatings. This comprehensive coating design not only improves the aesthetics of the thermos cup, but also provides effective protection for the outer tank 1, preventing the outer tank 1 from rusting and scratching. Moreover, the enamel porcelain coating makes stains not easily adhere, making cleaning more convenient and fast.

[0053] It is worth mentioning that the connection between the inner liner and the outer liner 1 of existing products is usually not specially treated, making it easy to accumulate dirt or corrode. In the present invention, an enamel porcelain coating is also applied to the connection at the top opening ends of the inner liner and the outer liner 1. The enamel porcelain coating tightly covers the connection, filling in any possible fine gaps, thereby enhancing the sealing performance. At the same time, the smooth surface of the coating makes the connection easier to clean, greatly improving the overall durability of the vacuum flask. Among them, the enamel porcelain coating can be light-colored.

[0054] Importantly, the exhaust hole 3 provided on the bottom cover 2 of the outer liner plays a crucial role in the manufacturing process. By providing the exhaust hole 3 on the bottom cover 2 of the outer liner, the gas impurities between the inner liner and the outer liner 1 can be evacuated using a low-temperature vacuum welding device and then the exhaust hole 3 can be sealed, ultimately forming a good vacuum layer, avoiding the influence of high temperature on the already formed enamel porcelain coating, and ensuring the color and quality of the coating.

[0055] In addition, the outer wall of the inner liner and the inner wall of the outer liner 1 are both coated with an enamel porcelain coating. In fact, during the production process of the high-temperature forming of the enamel porcelain coating, an oxide layer is easily formed on the outer wall of the inner liner and the inner wall of the outer liner 1, and the oxide layer is prone to adsorbing gas and water vapor. This leads to the release of the gas and water vapor adsorbed by the oxide layer to a certain extent during the vacuum pumping process, making it difficult to achieve an ideal vacuum state. Even if a relatively high vacuum degree is achieved in a short time, over time, these adsorbed substances may gradually escape, damaging the vacuum environment. Therefore, coating the outer wall of the inner liner and the inner wall of the outer liner 1 with an enamel porcelain coating can avoid the generation of the oxide layer and ensure the formation quality of the vacuum layer. In addition, the enamel porcelain material itself has a relatively low thermal conductivity. Therefore, coating the outer wall of the inner liner and the inner wall of the outer liner 1 with an enamel porcelain coating can, to a certain extent, serve as an additional heat insulation layer to reduce heat dissipation.

[0056] In addition, the thickness of the enamel porcelain coating is 0.1 mm - 0.5 mm. By controlling the thickness of the enamel porcelain coating between 0.1 mm and 0.5 mm, it can be ensured that the coating is thick enough to provide effective protection against scratches, corrosion, etc. to the inner liner and the outer liner 1, while not being too thick to cause an increase in brittleness or affect the stability of the overall structure. This thickness range can balance hardness and flexibility, extending the service life of the vacuum flask.

[0057] In summary, such an enamel porcelain double-layer vacuum flask and its manufacturing method, by adopting low-temperature vacuum welding technology, avoid the influence of high-temperature environment on the light-colored enamel porcelain coating on the outer wall of the vacuum flask, meeting the needs of customers for light-colored enamel porcelain double-layer vacuum flasks.

[0058] The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A manufacturing method of an enamel porcelain double-layer vacuum heat preservation cup, characterized in that: It includes the following technological steps carried out in sequence: S1: Process the pipe into the shapes of the required inner liner and outer liner, press the inner liner into the outer liner, and then connect the open ends of the inner liner and the outer liner together through a welding process; S2: Coat the inner liner and the outer liner with enamel glaze, and then put them into a high-temperature furnace for firing to form an enamel porcelain coating; S3: Process exhaust holes on the bottom cover of the outer liner, adhere the suction sheet to the bottom cover of the outer liner, and then weld the bottom cover of the outer liner to the bottom of the outer liner, while ensuring that the suction sheet is located between the inner liner and the outer liner; S4: Place the semi-finished thermos cup in a device adopting a low-temperature vacuum sealing process, evacuate the gas impurities between the inner liner and the outer liner through the exhaust holes to form a vacuum layer, and then use the sealing means in the low-temperature vacuum sealing process to block the exhaust holes in the device; S5: Place the thermos cup on a heating device, and heat the bottom cover of the outer liner through local heating to activate the suction sheet; S6: Bond the silica gel anti-slip pad to the bottom of the outer liner.

2. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 1, characterized in that: In the step S3, a plurality of exhaust holes are provided, and the plurality of exhaust holes are evenly spaced.

3. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 2, characterized in that: The exhaust holes are circular or strip-shaped.

4. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 3, wherein: In the step S4, the equipment adopting the low-temperature vacuum sealing process is a low-temperature vacuum welding equipment, the welding temperature is 150 - 300 °C, and the vacuum degree ≤ 10 -4 Pa.

5. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 4, characterized in that: In the step S5, the heating device is an electric furnace, and the local heating method is to only make the bottom cover of the outer liner contact the heating area of the electric furnace.

6. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 5, wherein: The temperature of the heating area of the electric furnace is 700 - 900 °C, and the heating time is 3 - 20 min.

7. The manufacturing method of the enamel porcelain double-layer vacuum heat preservation cup according to claim 1, characterized in that: The step S2 further includes: before coating the enamel glaze, first perform surface sandblasting treatment on the inner liner and the outer liner.

8. An enamel porcelain double-layer vacuum heat preservation cup manufactured by the method according to claim 1, characterized in that: It includes an inner liner, an outer liner and a bottom cover of the outer liner. The top open ends of the inner liner and the outer liner are connected by welding. A vacuum layer is formed between the inner liner and the outer liner. The bottom cover of the outer liner is connected to the bottom of the outer liner by welding. Exhaust holes are provided on the bottom cover of the outer liner. Enamel porcelain coatings are applied on the inner wall of the inner liner and the outer wall of the outer liner. An enamel porcelain coating is applied at the connection of the top open ends of the inner liner and the outer liner.

9. The enamel porcelain double-layer vacuum heat preservation cup according to claim 8, wherein: Enamel porcelain coatings are applied on the outer wall of the inner liner and the inner wall of the outer liner.

10. The enamel porcelain double-layer vacuum heat preservation cup according to claim 8, characterized in that: The thickness of the enamel porcelain coating is 0.1 mm - 0.5 mm.

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