A stainless steel thick film heating cup with a thick bottom and a thin body and its preparation method

Abstract

The present invention relates to the technical field of thick-film heating, and discloses a preparation method of a stainless-steel thick-film heating cup. The preparation method includes: stamping and stretching a stainless-steel sheet to obtain an integrally formed blank; coating a thick-film material on the lower bottom surface of the blank, performing sintering treatment, and cooling to obtain a semi-finished product; processing the cup body of the semi-finished product by spinning to make the thickness of the cup body thinner and the height meet the dimensional requirements, obtaining a finished stainless-steel thick-film heating cup; wherein, the temperature curve of the sintering treatment includes: heating from room temperature to 200-260°C; heating from 200-260°C to 600-660°C; heating from 600-660°C to 840-870°C. Implementing the preparation method of the present invention can reduce the operation process, lower the cost, while reducing the cleaning difficulty of the stainless-steel thick-film heating cup, and has excellent mechanical properties, heating performance and energy-saving effect of more than 20%, and the heating speed in the front stage is significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thick film heating, and particularly relates to a stainless steel thick film heating cup with a thick bottom and a thin body and a preparation method thereof. Background Art

[0002] Thick film heating is a technical means that uses an array film process to print insulating media, heating resistors, conductors, glass protective glazes and other materials on a substrate, forms a thick film integrated circuit after high-temperature sintering, and finally converts electrical energy into heat energy for heating. It is currently widely used in household appliances such as electric kettles, electric coffee pots, electric water heaters, hair straighteners, electric irons, humidifiers and instruments. Among them, the stainless steel thick film heating technology is one of the most widely used heating methods in industrial production. The stainless steel thick film heating technology can make heat fully and evenly transferred to the heated body, and has advantages such as good heat conduction performance, large heating area and high safety performance.

[0003] In the prior art, stainless steel thick film heaters usually adopt a welding process to form after fitting components. For example, a stainless steel thick film heating cup usually has a thick film circuit printed on the lower surface of the bottom of the cup, and an external contact point is provided on the bottom of the cup. Finally, the bottom of the cup and the body are combined by welding technology to form a complete heating cup. However, using the welding process will inevitably generate welds inside the heating cup, increasing the cleaning difficulty. Moreover, the thickness of the body of the prepared heating cup is uniform, increasing the consumption of raw materials and thus increasing the cost. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a stainless steel thick film heating cup with a thick bottom and a thin body and a preparation method thereof, which can reduce the operation process, reduce the cost, and at the same time reduce the cleaning difficulty of the stainless steel thick film heating cup.

[0005] To solve the above technical problem, in the first aspect of the present invention, a preparation method of a stainless steel thick film heating cup with a thick bottom and a thin body is provided. The stainless steel thick film heating cup includes a bottom and a body, the thickness of the bottom is greater than that of the body, and a thick film circuit is provided on the lower bottom surface of the bottom. The preparation method includes:

[0006] Stamping and stretching a stainless steel sheet to obtain an integrally formed blank;

[0007] Coating a thick film material on the lower bottom surface of the blank, performing sintering treatment, and cooling to obtain a semi-finished product;

[0008] Processing the body of the semi-finished product by spinning to make the thickness of the body thinner and the height meet the dimensional requirements, obtaining a finished stainless steel thick film heating cup;

[0009] As an improvement to the above solution, the temperature curve of the sintering treatment includes:

[0010] Raise the temperature from room temperature to 200 - 260 °C to dry the thick film material, reducing the lattice distortion of the stainless steel and lowering the internal stress;

[0011] Raise the temperature from 200 - 260 °C to 600 - 660 °C to bond the thick film material with the stainless steel material and promote the initial growth of new non-distorted small lattices;

[0012] Raise the temperature from 600 - 660 °C to 840 - 870 °C to form a dense coating of the thick film material on the bottom of the cup and promote the growth and increase of the stainless steel grains;

[0013] After coating the thick film material on the lower bottom surface of the green body, repeat the treatment 3 - 8 times according to the temperature curve of the sintering treatment, and cool down to room temperature by natural cooling before starting the next repeated sintering treatment.

[0014] As an improvement to the above solution, the temperature curve of the sintering treatment includes:

[0015] The heating belt speed for raising the temperature from room temperature to 200 - 260 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min;

[0016] The heating belt speed for raising the temperature from 200 - 260 °C to 600 - 660 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min;

[0017] The heating belt speed for raising the temperature from 600 - 660 °C to 840 - 870 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min.

[0018] As an improvement to the above solution, the temperature curve of the sintering treatment includes:

[0019] The heating belt speed for raising the temperature from room temperature to 240 - 260 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min;

[0020] The heating belt speed for raising the temperature from 240 - 260 °C to 640 - 660 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min;

[0021] The heating belt speed for raising the temperature from 640 - 660 °C to 850 - 870 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min.

[0022] As an improvement of the above solution, when the spinning process is used to process the cup body, the downward pressure is 0.3-1 mm, the rotational speed is 1000-2200 revolutions per minute, and the feeding speed is 500-1500 revolutions per minute.

[0023] As an improvement of the above solution, the thickness of the cup body of the integrally formed blank is a, and the thickness of the cup body of the finished stainless steel thick film heating cup after spinning is b, and b=(0.4-0.6)*a.

[0024] As an improvement of the above solution, b≥0.3 mm;

[0025] The thickness of the cup bottom of the finished stainless steel thick film heating cup after spinning is c, and c≥0.6 mm.

[0026] As an improvement of the above solution, the chemical composition of the stainless steel sheet includes, by mass percentage: C≤0.08%, Cr=16.00-20.00%, Ni=8.00-14.00%, Si≤1.00%, Mn≤2.00%, P≤0.045%, Mo=0-3.00%;

[0027] The chemical composition of the stainless steel sheet further includes 0-1.2% of Al by mass percentage.

[0028] As an improvement of the above solution, a microwave source is further provided in the sintering section at 600-660 °C to perform microwave sintering on the blank with the thick film material coated on the lower bottom surface. The power of the microwave source is 1-2 kW, and the frequency is 1-5 GHz.

[0029] Correspondingly, the second aspect of the present invention further provides a stainless steel thick film heating cup with a thick cup bottom and a thin cup body, which is prepared by the preparation method of the stainless steel thick film heating cup with a thick cup bottom and a thin cup body.

[0030] Implementing the present invention has the following beneficial effects:

[0031] In the present invention, a blank is obtained by stamping and stretching a stainless steel sheet, and then a thick film material is coated on the lower bottom surface of the blank and sintered. Finally, the cup body is processed by a spinning process to obtain a stainless steel thick film heating cup with a thick cup bottom and a thin cup body. The preparation method is simple, and the traditional welding process is avoided, so that there are no gaps in the inner wall of the heating cup, reducing the cleaning difficulty. In addition, the cup body and the cup bottom of the present invention are integrally formed, and the thickness of the cup body becomes thinner after the spinning process treatment, so that the height meets the requirements, reducing the raw material consumption, reducing the cost, and having an energy-saving effect of more than 20%, and the heating speed in the front stage is significantly improved. Specific embodiments

[0032] To make the objectives, technical solutions and advantages of the present invention more clear, the following specific embodiments will be used to further describe the present invention in detail.

[0033] To solve the above problems, a first aspect of the present invention provides a preparation method for a stainless steel thick film heating cup with a thick bottom and a thin body. The stainless steel thick film heating cup with a thick bottom and a thin body includes a bottom and a body. The thickness of the bottom is greater than that of the body. A thick film circuit is provided on the lower bottom surface of the bottom. The preparation method includes:

[0034] Stamping and stretching a stainless steel sheet to obtain an integrally formed blank;

[0035] Coating a thick film material on the lower bottom surface of the blank, performing a sintering treatment, and then cooling to obtain a semi-finished product;

[0036] Processing the body of the semi-finished product by spinning to make the thickness of the body thinner and the height meet the dimensional requirements, obtaining a finished stainless steel thick film heating cup;

[0037] The thick film circuit can be formed on the substrate by means of screen printing and sintering and other techniques to play its heating role. Therefore, in the present invention, by sintering the blank coated on the lower bottom surface, on the one hand, a thick film circuit can be obtained on the lower bottom surface of the stainless steel cup bottom, and on the other hand, a formed heating cup can be obtained, avoiding the use of welding processes. As a result, the inner wall of the obtained stainless steel thick film heating cup is smooth and there are no gaps. More importantly, through the sintering treatment, the metallographic structure of the stainless steel material can be changed, and then the performance of the stainless steel material can be changed, prompting it to be deformed under the spinning process, making the thickness of the body thinner and the height higher, obtaining a stainless steel thick film heating cup that meets the dimensions.

[0038] Preferably, the chemical composition of the stainless steel sheet by mass percentage includes: C≤0.08%, Cr = 16.00 - 20.00%, Ni = 8.00 - 14.00%, Si≤1.00%, Mn≤2.00%, P≤0.045%, Mo = 0 - 3.00%. Among them, C and Si can improve the strength, hardness and elasticity of stainless steel. If the content is too high, its toughness and plasticity will be too high to change the thickness of the body by spinning. The Cr element and Ni element can improve the toughness of stainless steel and at the same time improve its heat resistance. If the content of Cr and Ni is too small, the corrosion resistance of the stainless steel thick film heating cup in a humid environment will be reduced and it is easy to rust; and the addition of a certain amount of Mo helps to improve the strength and toughness of the stainless steel blank, and improve the tensile strength and yield strength of the material. Further, the stainless steel sheet can be 304 stainless steel sheet, 316 stainless steel sheet, 316L stainless steel sheet, etc.

[0039] Furthermore, the chemical composition of the stainless steel sheet further includes 0 to 1.2% Al by mass percentage, more preferably 0.4 to 1.2% Al. Adding Al to the alloy may increase the content of ferrite in the system. The hardness and yield strength of the stainless steel sheet obtained by warm rolling process are improved, which is beneficial to thinning the cup body under a specific spinning process. Moreover, Al atoms may react preferentially with C atoms in the system, consuming some C atoms and hindering the diffusion of C atoms to the grain boundary, thus improving the corrosion resistance of the stainless steel sheet. If the Al content is too high, it may lead to an excessive volume fraction of the ferrite phase, reducing the plastic deformation ability of the stainless steel sheet.

[0040] Among them, the temperature curve of the sintering treatment includes: heating from room temperature to 200 - 260°C; heating from 200 - 260°C to 600 - 660°C; heating from 600 - 660°C to 840 - 870°C. When the stainless steel sheet is at 200 - 260°C, there are a large number of pores in the system, and the distribution, size, and shape of the pores are uneven. As the sintering temperature rises to 600 - 660°C, the atomic diffusion degree becomes more and more intense during the process, and the volume diffusion and mass transfer process of the material itself are more sufficient. Moreover, the heat treatment releases the internal stress between the grains, prompting the particles to rearrange their positions and grow in the same growth direction, resulting in a decrease in the pore size of the sample, a rapid increase in the densification degree and density of the system, and promoting the homogenization of the alloy in the green body, and recrystallization begins to occur. Finally, it is heated to 840 - 870°C. At this time, it begins to approach the phase transition temperature of the stainless steel material, which may cause the alloying elements in the system to start to dissolve, making the internal element composition evenly distributed, and the internal grains begin to disappear. The grains in the structure are mainly the original deformed grains, and the formed fine recrystallized grains will continue to grow. Precipitation phases begin to form at the grain boundaries and inside the grains, further improving the density of the stainless steel system. Moreover, the pore shape also changes from irregular to regular and spherical, resulting in cracks not easily spreading at the pores, thereby improving the toughness and ductility of the stainless steel heating cup. If the heating rate is too fast, pores will appear in the thick film coating, damaging the performance of the thick film material.

[0041] Therefore, in the present invention, the conventional high-temperature treatment of stainless steel materials above 1000 °C is avoided. By heating from room temperature to 200 - 260 °C, the thick film material is dried, reducing the lattice distortion of stainless steel and lowering the internal stress. Subsequently, heating from 200 - 260 °C to 600 - 660 °C enables the thick film material to bond with the stainless steel material and promotes the start of growth of new small lattices without distortion. Finally, heating from 600 - 660 °C to 840 - 870 °C forms a dense coating of the thick film material on the bottom of the cup and promotes the growth and increase of the grains of stainless steel. This not only improves the ductility and toughness mechanical properties of stainless steel, enabling the thickness of the cup body to be stretched and thinned through the spinning process, but also results in a thick film with stable, safe, and uniform heat conduction.

[0042] In some specific and preferred embodiments, a microwave source is further provided in the sintering section at 600 - 660 °C for microwave sintering of the blank with the thick film material coated on the lower bottom surface. There is very little internal stress in this wavelength band. Through traditional heat source sintering, the particles in the system start to rearrange and grow in the same growth direction. Combining the set microwave source can heat the blank from the inside to the outside, enabling the blank to be heated evenly simultaneously inside and outside, better promoting the start of growth of new small lattices without distortion, and promoting an increase in the densification degree of the system. The power of the microwave source is 1 - 2 kW, and the frequency is 1 - 5 GHz. Combining with the heating belt speed and sintering time in the sintering section at 600 - 660 °C, new thermal stress is avoided from being generated in the blank, which would otherwise affect the stretching performance of the semi-finished stainless steel thick film heating cup. At the same time, coordinating with the sintering at 840 - 870 °C can avoid excessive grain growth, which would affect the microstructure and mechanical properties of the semi-finished stainless steel thick film heating cup and render it unusable for the spinning process. If it is set in the sintering section at 200 - 260 °C, there may be problems of fast heating rate and incomplete stress relief. If a microwave source is set in the sintering section at 840 - 870 °C, it may affect the performance of the thick film material.

[0043] At this time, the semi-finished product after sintering treatment still cannot reach the highest density and the best mechanical properties. However, if the sintering temperature is higher than 870 °C, it will cause structural gelatinization of the resistance material in the thick film material, etc., thereby affecting the heating performance of the heating cup. Therefore, after coating the thick film material on the lower bottom surface of the green body, the inventor repeats the sintering treatment 3 to 8 times according to the temperature curve of the sintering treatment, and cools down to room temperature by natural cooling before starting the next repeated sintering treatment, further improving the toughness, tensile strength and mechanical properties of the stainless steel system, so as to facilitate the subsequent processing of the thickness of the cup body by the spinning process. If the number of repeated sintering treatments is too small, the thick film circuit cannot be fully sintered, resulting in unstable resistance values and poor modification effects on the mechanical properties of the stainless steel semi-finished product. If the number of repeated sintering treatments is too large, it will cause grain coarsening, thereby reducing the mechanical properties of the stainless steel.

[0044] Further preferably, the temperature curve of the sintering treatment includes: the heating belt speed from room temperature to 200 - 260 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min; the heating belt speed from 200 - 260 °C to 600 - 660 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min; the heating belt speed from 600 - 660 °C to 840 - 870 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min. The heating rate in the previous stage has a significant increase. By controlling the sintering time of the stainless steel material in the sintering furnace and the transmission speed of the heating belt, it can promote uniform heat conduction during the sintering treatment of the stainless steel, facilitate maintaining the same metallographic structure in each temperature region, and the grains gradually coarsen and have uniform sizes, thereby further improving the mechanical properties and physical properties of the stainless steel thick film heating cup, and enabling the thick film material to be fully sintered, thereby improving the heating performance of the heating cup. More preferably, the heating belt speed from room temperature to 240 - 260 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min; the heating belt speed from 240 - 260 °C to 640 - 660 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min; the heating belt speed from 640 - 660 °C to 850 - 870 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min.

[0045] Furthermore, the sintering treatment also includes cooling the semi-finished product to room temperature after the repeated sintering treatment. The cooling rate will affect the grain size in the stainless steel. As the temperature decreases, the grains will gradually grow to form large particles. In the present invention, the cooling method adopts natural cooling to avoid the grain size in the stainless steel system from being too large, resulting in a decrease in mechanical properties and being unable to reach the required size during the subsequent spinning treatment of the cup body. If the cooling rate is too fast, the ductility and toughness of the material will be significantly reduced.

[0046] Preferably, when the spinning process is used to process the cup body, the downward pressure is 0.3 - 1 mm, the rotation speed is 1000 - 2200 revolutions / min, and the feeding speed is 500 - 1500 revolutions / min. Controlling the pressure, rotation speed, and feeding speed within the above ranges can achieve the stretching treatment of the stainless steel cup body, making its thickness as thin as possible and its height as high as possible. Moreover, in combination with a specific sintering process and cooling rate, it can maintain excellent impact resistance, corrosion resistance, and hardness of the stainless steel thick-film heating cup. The retention rates of impact resistance, corrosion resistance, and hardness at the same thickness reach 95 - 100%, with high consistency. More importantly, the circuit structure of the thick film will not be damaged during the stretching process of the cup body by spinning, enabling it to have uniform heat conduction performance, and its thermal conductivity coefficient is more than 99% of that of the thick-film heater obtained by the conventional sintering process.

[0047] Furthermore, using the spinning process can reduce the thickness of the cup body by 40 - 60%, reducing costs and accelerating the heating speed, achieving an energy-saving effect. Therefore, in the present invention, the thickness of the cup body of the integrally formed blank is a, and the thickness of the cup body of the finished stainless steel thick-film heating cup after spinning is b, where b = (0.4 - 0.6) * a.

[0048] In some specific and preferred embodiments, b ≥ 0.3 mm; the thickness of the cup bottom of the finished stainless steel thick-film heating cup after spinning is c, where c ≥ 0.6 mm. If the thickness of the cup bottom is too small, it is prone to deformation during multiple sintering processes, which will cause the entire stainless steel thick-film heating cup to deform and damage the thick-film circuit, reducing the product yield and bringing more potential safety hazards. More preferably, b = 0.5 - 0.8 mm and c = 1.2 - 1.5 mm.

[0049] Correspondingly, the present invention also provides a stainless steel thick-film heating cup prepared by the above preparation method.

[0050] The following further illustrates the present invention with specific examples:

[0051] Example 1

[0052] This example provides a stainless steel thick-film heating cup, including a cup bottom and a cup body. A thick-film circuit is provided on the lower bottom surface of the cup bottom. Its preparation method is as follows:

[0053] (1) Stamping and stretching a 316 stainless steel sheet to form an integrally formed blank with a cup bottom thickness of 1.2 mm and a cup body thickness of 1.2 mm;

[0054] (2) Coating on the lower bottom surface of the blank, performing sintering treatment, and naturally cooling to room temperature to obtain a semi-finished product;

[0055] The specific sintering process is as follows: heating from room temperature to 250°C, with a heating belt speed of 200 mm / min and a heating time of 20 min; then heating from 250°C to 650°C and holding for 6 min, with a heating belt speed of 200 mm / min and a heating time of 20 min; finally heating from 650°C to 860°C, with a heating belt speed of 200 mm / min and a heating time of 20 min. Then, after natural cooling to room temperature, the above sintering process is repeated 5 times, and the total sintering process is carried out 6 times.

[0056] (3) After the semi-finished product after sintering treatment is naturally cooled to room temperature, the cup body of the semi-finished product is processed by a spinning process to reduce the thickness of the cup body from 1.2 mm to 0.7 mm, obtaining a finished stainless steel thick film heating cup.

[0057] The specific spinning process includes: a downward pressure of 0.6 mm, a rotation speed of 1600 revolutions / min, and a feeding speed of 1000 revolutions / min.

[0058] The hardness of the stainless steel thick film heating cup with a thick bottom and a thin cup body obtained by the preparation process in Example 1 is in the range of 89 - 93 HRB, the impact work at room temperature is in the range of 67 - 70 J / cm, and the thermal efficiency is 98 - 99%. It can be seen that the sintering treatment and spinning treatment have no obvious influence on the mechanical properties of stainless steel, and the thermal efficiency remains stable, and the consistency of the product is high.

[0059] Example 2

[0060] This example provides a stainless steel thick film heating cup, including a cup bottom and a cup body. A thick film circuit is provided on the lower bottom surface of the cup bottom. Its preparation method is as follows:

[0061] (1) A 304 stainless steel sheet is stamped and drawn into a one-piece blank with a cup bottom thickness of 1.5 mm and a cup body thickness of 1.5 mm.

[0062] (2) Coating is applied on the lower bottom surface of the blank, followed by sintering treatment and natural cooling to room temperature to obtain a semi-finished product.

[0063] The specific sintering process is as follows: heating from room temperature to 250°C, with a heating belt speed of 200 mm / min and a heating time of 20 min; then heating from 250°C to 650°C, with a heating belt speed of 200 mm / min and a heating time of 20 min; finally heating from 650°C to 860°C, with a heating belt speed of 200 mm / min and a heating time of 20 min. Then, after natural cooling to room temperature, the above sintering process is repeated 5 times, and the total sintering process is carried out 6 times.

[0064] (3) After the semi-finished product after sintering treatment is naturally cooled to room temperature, the cup body of the semi-finished product is processed by a spinning process to reduce the thickness of the cup body from 1.5 mm to 0.8 mm, obtaining a finished stainless steel thick film heating cup.

[0065] The specific spinning process includes: the downward pressure is 0.5 mm, the rotation speed is 1500 revolutions / min, and the feeding speed is 1100 revolutions / min.

[0066] The hardness of the stainless steel thick film heating cup with a thick cup bottom and a thin cup body obtained by the preparation process in Example 2 is in the range of 86-90 HRB, the impact work at room temperature is in the range of 78-80 J / cm, and the thermal efficiency of the heating cup is 98-99%. It can be seen that the sintering treatment and spinning treatment have no obvious influence on the mechanical properties of stainless steel, and the thermal efficiency also remains stable, and the consistency of the product is high.

[0067] Example 3

[0068] This example provides a stainless steel thick film heating cup, including a cup bottom and a cup body. A thick film circuit is provided on the lower bottom surface of the cup bottom. Its preparation method is as follows:

[0069] (1) Stamp and stretch a 304 stainless steel sheet to form an integrally formed blank with a cup bottom thickness of 1.5 mm and a cup body thickness of 1.5 mm.

[0070] (2) Coat the lower bottom surface of the blank, perform sintering treatment, and naturally cool to room temperature to obtain a semi-finished product.

[0071] The specific sintering treatment process is: heat up from room temperature to 250 °C, the heating belt speed is 200 mm / min, and the heating time is 20 min; then heat up from 250 °C to 650 °C, and a microwave source is also provided in this sintering section. The power of the microwave source is 1.2 kW, the frequency is 2.0 GHz, the heating belt speed is 150 mm / min, and the heating time is 20 min; finally, heat up from 650 °C to 860 °C, the heating belt speed is 200 mm / min, and the heating time is 20 min. Then, after naturally cooling to room temperature, repeat the above sintering treatment process 3 times, and a total of 4 sintering treatments are carried out.

[0072] (3) After the semi-finished product after sintering treatment is naturally cooled to room temperature, the cup body of the semi-finished product is processed by a spinning process to reduce the thickness of the cup body from 1.5 mm to 0.8 mm, obtaining a finished stainless steel thick film heating cup.

[0073] The specific spinning process includes: the downward pressure is 0.5 mm, the rotation speed is 1500 revolutions / min, and the feeding speed is 1100 revolutions / min.

[0074] The hardness of the stainless steel thick film heating cup with a thick bottom and a thin body obtained by the preparation process in Example 3 is in the range of 88.5 - 90 HRB, the impact work at room temperature is in the range of 78.5 - 80 J / cm, and the thermal efficiency of the heating cup is 98.6 - 99.5%. It can be seen that the sintering treatment and spinning treatment have no obvious effect on the mechanical properties of stainless steel, and the thermal efficiency remains stable, and the consistency of the product is high.

[0075] The above-disclosed is only a preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A preparation method of a stainless steel thick film heating cup with a thick bottom and a thin body, characterized in that, The stainless steel thick film heating cup includes a cup bottom and a cup body. The thickness of the cup bottom is greater than that of the cup body. A thick film circuit is provided on the lower bottom surface of the cup bottom. The preparation method includes: Stamping and stretching a stainless steel sheet to obtain an integrally formed blank; Coating a thick film material on the lower bottom surface of the blank, performing sintering treatment, and cooling to obtain a semi-finished product; Processing the cup body of the semi-finished product by spinning to make the thickness of the cup body thinner and the height meet the dimensional requirements, obtaining the finished stainless steel thick film heating cup; The temperature curve of the sintering treatment includes: Heating from room temperature to 200 - 260 °C to dry the thick film material, reducing the lattice distortion of the stainless steel and lowering the internal stress; Heating from 200 - 260 °C to 600 - 660 °C to bond the thick film material with the stainless steel material and promote the start of growth of new non-distorted small lattices; Heating from 600 - 660 °C to 840 - 870 °C to form a dense coating of the thick film material on the cup bottom and promote the growth and increase of the stainless steel grains; After coating the thick film material on the lower bottom surface of the blank, repeating the treatment according to the temperature curve of the sintering treatment 3 - 8 times, and cooling to room temperature by natural cooling before starting the next repeated sintering treatment.

2. The manufacturing method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, The temperature curve of the sintering treatment includes: The heating belt speed from room temperature to 200 - 260 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min; The heating belt speed from 200 - 260 °C to 600 - 660 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min; The heating belt speed from 600 - 660 °C to 840 - 870 °C is 100 - 300 mm / min, and the heating time is 30 - 10 min.

3. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 2, characterized in that, The temperature curve of the sintering treatment includes: The heating belt speed from room temperature to 240 - 260 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min; The heating belt speed from 240 - 260 °C to 640 - 660 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min; The heating belt speed from 640 - 660 °C to 850 - 870 °C is 150 - 250 mm / min, and the heating time is 15 - 25 min.

4. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, When processing the cup body by the spinning process, the downward pressure is 0.3 - 1 mm, the rotation speed is 1000 - 2200 revolutions / min, and the feeding speed is 500 - 1500 revolutions / min.

5. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, The thickness of the cup body of the integrally formed blank is a, and the thickness of the cup body of the finished stainless steel thick film heating cup after spinning is b, b = (0.4 - 0.6) * a.

6. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, The thickness of the cup body of the finished stainless steel thick film heating cup after spinning is b, b ≥ 0.3 mm; The thickness of the cup bottom of the finished stainless steel thick film heating cup after spinning is c, c ≥ 0.6 mm.

7. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, The chemical composition of the stainless steel sheet includes, by mass percentage: C ≤ 0.08%, Cr = 16.00 - 20.00%, Ni = 8.00 - 14.00%, Si ≤ 1.00%, Mn ≤ 2.00%, P ≤ 0.045%, Mo = 0 - 3.00%; The chemical composition of the stainless steel sheet further includes 0 - 1.2% of Al by mass percentage.

8. The preparation method of the stainless steel thick film heating cup with a thick bottom and a thin body as claimed in claim 1, characterized in that, A microwave source is further provided in the sintering section at 600 - 660 °C to perform microwave sintering on the green body with the thick film material coated on the lower bottom surface. The power of the microwave source is 1 - 2 kW and the frequency is 1 - 5 GHz.

9. A stainless steel thick film heating cup with a thick bottom and a thin body, characterized in that, The stainless steel thick film heating cup with a thick bottom and a thin body is prepared by the preparation method described in any one of claims 1 - 8.