Coating device and coating method

Abstract

The invention relates to the technical field, and provides a coating device and a coating method.The coating device comprises a fixing part, a coating part and a rotating part, and the fixing part is used for being connected with an external driving mechanism; the coating part comprises a spray head, the spray head is provided with a coating surface facing the surface of the to-be-coated object, a spraying hole is formed in the coating surface, two coating supporting parts are arranged on the coating surface, and the two coating supporting parts are used for abutting against the surface of the to-be-coated object and are arranged on the two opposite sides of the spraying hole at intervals in the direction perpendicular to the coating direction; and the rotating part is arranged on the fixed part, the rotating part is connected with the coating part, and the extending direction of a rotating center shaft of the rotating part is parallel to the coating direction. The coating device provided by the invention is simpler, more efficient and more intuitive in the aspect of checking the coating parallelism, and can also ensure the consistency and repeatability of slurry coating.

Description

Technical Field

[0001] This invention relates to the field of vacuum glass production equipment technology, and in particular provides a coating device and coating method. Background Technology

[0002] In the production and manufacturing process of vacuum glass, coating sealing material is an indispensable step and a key link that determines the vacuum life of the product and the final yield. Usually, metallization paste or glass powder paste is used to tightly coat the edges of two glass substrates and sinter to form an airtight sealing edge.

[0003] Currently, slurry coating equipment typically employs a coating head with a fixed angle, which is mounted on a multi-axis (e.g., XYZ three-axis) motion platform to achieve coating of complex patterns. The parallelism between the scraping edge of the coating head and the surface of the glass substrate is crucial to the uniformity of the slurry layer.

[0004] Typically, the slurry thickness is determined by precisely controlling the gap (Z-axis height) between the coating head and the glass surface. This control system relies on real-time feedback from a high-precision Z-axis servo system and height measurement units such as displacement sensors. However, this control system is extremely sensitive to external factors. For example, during the movement of the coating mechanism driven by the gantry, even slight vibrations of the machine can cause the coating head to vibrate, resulting in wavy streaks in the wet slurry film. Furthermore, slight warping or unevenness inherent in the glass substrate itself, as well as sensor calibration drift, can directly introduce thickness control errors, leading to unstable and inconsistent slurry thickness. The coated slurry surface exhibits obvious wavy patterns with significant differences between peaks and troughs. This uneven sealing surface results in insufficient airtightness during subsequent sintering and sealing processes and easily creates stress concentration points, which is one of the main causes of vacuum failure and product scrap. Summary of the Invention

[0005] The purpose of this invention is to provide a coating apparatus and coating method, which aims to solve the problems of difficult parallelism verification and low coating accuracy of existing coating apparatuses.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, embodiments of this application provide a coating apparatus for performing a coating action on the surface of an object to be coated, including: The fixing part is used to connect to the peripheral drive mechanism; The coating section includes a nozzle having a coating surface facing the surface of the object to be coated. The coating surface has spray holes and two coating support portions for abutting against the surface of the object to be coated. These two support portions are spaced apart on opposite sides of the spray holes along a direction perpendicular to the coating direction. A rotating part is provided on the fixed part and connected to the coating part. The extension direction of the rotation center axis of the rotating part is parallel to the coating direction.

[0007] The beneficial effects of the present invention are as follows: The coating device provided by the present invention has a coating nozzle whose angular orientation relationship with the surface of the object to be coated is adjusted by a rotating part. At the same time, the thickness of the slurry is determined by the height of the coating support part. Compared with the traditional method of using Z-axis height sensing and closed-loop feedback control system to determine the thickness, the coating device of the present application is simpler, more efficient and more intuitive in verifying the parallelism of the coating, and can also ensure the consistency and repeatability of the slurry coating.

[0008] In some embodiments, the coating apparatus includes a telescopic section, the telescopic direction of which is perpendicular to the surface of the object to be coated, and the coating section is connected to the rotating section via the telescopic section.

[0009] In some embodiments, the rotating part includes a rotating support connected to the fixed part and a rotating body rotatably connected to the rotating support about an axis, the rotating body being connected to the telescopic part.

[0010] In some embodiments, the rotating part further includes a fine-tuning part disposed on the rotating support base, and the rotating body is provided with a force-receiving part that abuts against the fine-tuning part, so that the rotating body rotates relative to the rotating support base about the rotation center axis.

[0011] In some embodiments, the telescopic portion includes a guide rail connected to the rotating portion and a slider connected to the coating portion, the slider being slidably connected to the guide rail.

[0012] In some embodiments, the nozzle includes a first portion and a second portion connected to the first portion, the first portion and the second portion being arranged in the same direction along the coating direction, the first portion having a first sub-surface, the second portion having a second sub-surface, the first sub-surface and the second sub-surface being joined together to form the coating surface, and the coating support portion being provided on the first sub-surface; The injection hole is formed on the first sub-surface; or, the injection hole is formed on the second sub-surface.

[0013] In some embodiments, the coating support includes a support block disposed on the first sub-surface; or, The first portion has a first wedge-shaped surface connected to the first sub-surface, the first wedge-shaped surface being set at an angle to the coating direction, and the coating support portion including a support block disposed on the first sub-surface and an extension block disposed on the first wedge-shaped surface, the support block being connected to the extension block.

[0014] In some embodiments, the coating section includes a bracket connected to the rotating section, a glue valve assembly disposed on the bracket, a pressure assembly connected to the glue valve assembly, and a nozzle disposed on the glue valve assembly, the nozzle being fixedly connected to the bracket.

[0015] Secondly, this application also provides a coating method, implemented using the coating apparatus described above, the coating method comprising the following steps: Select the appropriate nozzle for the coating section based on the width and thickness of the slurry coating; The object to be coated is subjected to edge detection to confirm the coating path, and a trial coating and scraping operation is performed on the surface of the object to be coated. The angular orientation of the nozzle is adjusted by rotating the nozzle so that the coating surface is parallel to the surface of the object to be coated, until the wet film thickness of the slurry coated on the surface of the object to be coated is uniform. The calibrated coating section is then used for formal coating, moving at a preset coating speed on the surface of the object to be coated.

[0016] The beneficial effects of the present invention are as follows: The present invention provides a coating method that, based on the above-mentioned coating device, makes the entire coating method simpler to operate and enables calibration work to be completed more quickly and intuitively, greatly reducing the reliance on the skills of professional personnel.

[0017] In some embodiments, prior to the step of performing formal coating on the calibrated coating section and moving it at a preset coating speed on the surface of the object to be coated, the coating method further includes: The coating section can float up and down relative to the surface of the object to be coated in the direction of its own gravity, and the nozzle abuts against the surface of the object to be coated under the action of gravity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a schematic diagram of the coating apparatus provided in an embodiment of the present invention; Figure 2 This is a left view of the coating apparatus provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the nozzle of the coating device provided in an embodiment of the present invention; Figure 4 for Figure 3 Enlarged view of point A in the middle; Figure 5 An exploded view of the nozzle of the coating apparatus provided in an embodiment of the present invention; Figure 6 A flowchart of the coating method provided in an embodiment of the present invention; Figure 7 Another flowchart of the coating method provided in an embodiment of the present invention.

[0020] The following are the labeling elements in the figure: 100. Coating apparatus; 10. Fixing part; 20. Coating section; 21. Nozzle; 21a. Coating surface; 21b. Spray nozzle; 21c. Coating support section; 211. First part; 212. Second part; 211a. First sub-surface; 212a. Second sub-surface; 211b. First wedge-shaped surface; 212b. Second wedge-shaped surface; 21c1. Support block; 21c2. Extension block; 22. Bracket; 23. Adhesive valve assembly; 24. Pressure assembly; 30. Rotating part; 31. Rotating support base; 32. Rotating body; 33. Fine-tuning part; 40. Telescopic part; 41. Guide rail; 42. Slider; X, coating direction; O, rotation center axis. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In related technical fields, slurry coating devices typically employ a coating head with a fixed angle, which is mounted on a multi-axis (e.g., XYZ three-axis) motion platform to achieve coating of complex patterns. The parallelism between the scraping edge of the coating head and the surface of the glass substrate is crucial to the uniformity of the slurry layer.

[0026] The slurry thickness is determined by precisely controlling the gap (Z-axis height) between the coating head and the glass surface. This control system relies on real-time feedback from a high-precision Z-axis servo system and height measurement units such as displacement sensors. However, this control system is extremely sensitive to external factors. For example, during the movement of the coating mechanism driven by the gantry, even slight vibrations of the machine can cause vibrations in the slurry head, resulting in wavy streaks in the wet film. Furthermore, slight warping or unevenness of the glass substrate itself, as well as sensor calibration drift, can directly introduce thickness control errors, leading to unstable and inconsistent slurry thickness. The coated slurry surface exhibits obvious wavy patterns with significant differences between peaks and troughs. This uneven sealing surface results in insufficient airtightness during subsequent sintering and sealing processes and easily creates stress concentration points, which is one of the main causes of vacuum failure and product scrap.

[0027] In view of this, this application provides a coating apparatus that adds a rotating part, the extension direction of which is parallel to the coating direction. This allows the nozzle of the coating part to be finely adjusted relative to the surface of the object to be coated. Furthermore, the coating support part is used to adjust the coating thickness of the slurry. Thus, the coating apparatus of this application is simpler, more efficient, and more intuitive in verifying the parallelism of the coating, and can also ensure the consistency and repeatability of the slurry coating.

[0028] Firstly, please refer to Figures 1 to 5 This application provides a coating apparatus 100 for coating an object on its surface, including a fixing part 10, a coating part 20, and a rotating part 30.

[0029] The fixing part 10 is used to connect to the external drive mechanism; the coating part 20 includes a nozzle 21, the nozzle 21 has a coating surface 21a facing the surface of the object to be coated, the coating surface 21a has a spray hole 21b, the coating surface 21a has two coating support parts 21c, the two coating support parts 21c are used to abut against the surface of the object to be coated, and are provided on opposite sides of the spray hole 21b at intervals perpendicular to the coating direction X; and the rotating part 30 is provided on the fixing part 10, the rotating part 30 is connected to the coating part 20, and the extension direction of the rotation center axis O of the rotating part 30 is parallel to the coating direction X.

[0030] Understandably, the fixing part 10 is a mechanism for connecting the coating device 100 to the peripheral drive mechanism. By connecting the fixing part 10 to the peripheral gantry, moving device, etc., the coating device 100 is driven to perform coating operations. Here, the structural form of the fixing part 10 includes, but is not limited to, a fixing bracket, a fixing plate, or a combination of the two. After the fixing part 10 is connected to the peripheral drive mechanism, it remains fixed.

[0031] The coating section 20 is a mechanism for storing and coating slurry. It should be understood that the coating section 20 should have a storage section for storing the slurry to be coated, a power section for driving the slurry to be sprayed out, and a nozzle 21. The nozzle 21 is a component that directly realizes the slurry coating and forming. The slurry is sprayed out from the spray hole 21b of the nozzle 21 and formed on the surface of the object to be coated. Since the coating section 20 keeps moving during the coating process, a continuous slurry coating with a certain thickness can be formed on the surface of the object to be coated.

[0032] The coating surface 21a is the end face of the nozzle 21 facing the surface of the object to be coated. The coating support 21c is used to maintain a gap between the coating surface 21a and the surface of the object to be coated. That is, the height of this gap is the thickness of the slurry coating. Therefore, coating support 21c of different heights can be replaced as needed to adjust the thickness of the slurry coating. There are two coating support 21cs, but their number can be adjusted according to actual usage requirements. The two coating support 21cs are spaced apart on opposite sides of the spray hole 21b along a direction perpendicular to the coating direction X. That is, when the two coating support 21cs abut against the surface of the object to be coated, the angular orientation of the two coating support 21cs relative to the surface of the object to be coated can be adjusted by the rotating part 30, thereby making the coating surface 21a parallel to the surface of the object to be coated. In this way, the thickness of the slurry sprayed from the spray hole 21b can be consistent.

[0033] The rotating part 30 should include a fixed part and a rotating part that rotates about an axis relative to the fixed part. The extension direction of the rotation axis of the rotating part should be parallel to the coating direction X. In this way, the fixed part is connected to the fixed part 10 and the rotating part is connected to the coating part 20, so that when the rotating part rotates about an axis relative to the fixed part, it can level the surface of the two coating support parts 21c on the nozzle 21 of the coating part 20 with respect to the object to be coated.

[0034] The coating apparatus 100 provided by the present invention has a coating section 20 in which the nozzle 21 is adjusted to the angular orientation of the object to be coated by the rotating section 30. At the same time, the thickness of the slurry is determined by the height of the coating support section 21c. Compared with the traditional method of using Z-axis height sensing and closed-loop feedback control system, the coating apparatus 100 of the present application is simpler, more efficient and more intuitive in verifying the parallelism of the coating, and can also ensure the consistency and repeatability of the slurry coating.

[0035] Please refer to Figures 1 to 5 In some embodiments, the coating apparatus 100 includes a telescopic part 40, the telescopic direction of which is perpendicular to the surface of the object to be coated, and the coating part 20 is connected to the rotating part 30 through the telescopic part 40.

[0036] Understandably, the structure of the telescopic part 40 includes, but is not limited to, a telescopic cylinder, a guide rail and a slider, or a combination of both. With the addition of telescopic extension, the coating part 20, aided by the telescopic part 40, can contact the surface of the object to be coated in real time. Especially when the surface of the object to be coated has unevenness issues such as undulations, the nozzle 21 can contact the surface of the object to be coated under the gravity of the coating part 20. Thus, the surface quality of the wet film of the slurry is significantly improved. Precise parallelism and a rigid, stable scraping edge ensure the hydrodynamic stability of the slurry during the coating process, thereby significantly reducing or even eliminating the generation of wavy lines and obtaining a smooth and even slurry surface.

[0037] Please refer to Figures 1 to 5 In some embodiments, the rotating part 30 includes a rotating support 31 connected to the fixed part 10 and a rotating body 32 rotatably connected to the rotating support 31 about an axis, the rotating body 32 being connected to the telescopic part 40.

[0038] Understandably, the rotating support 31 is the fixed part of the rotating part 30, and the rotating body 32 is the rotating part of the rotating part 30. The two are connected by shafts such as rotating shafts and bearings.

[0039] Please refer to Figures 1 to 5 In some embodiments, the rotating part 30 further includes a fine-tuning part 33, which is disposed on the rotating support 31. The rotating body 32 is provided with a force-receiving part that abuts against the fine-tuning part 33, so that the rotating body 32 rotates relative to the rotating support 31 around the rotation center axis O.

[0040] Understandably, the fine-tuning part 33 can allow the rotating body 32 to make small-range adjustments relative to the rotating support 31. For example, the fine-tuning part 33 can be a micrometer. When the micrometer rotates, it directly acts on the force-bearing part to drive the rotating body 32 to rotate around the axis relative to the rotating support 31.

[0041] Please refer to Figures 1 to 5 In some embodiments, the telescopic part 40 includes a guide rail 41 connected to the rotating part 30 and a slider 42 connected to the coating part 20, the slider 42 being slidably connected to the guide rail 41.

[0042] Understandably, the lifting coating section 20 between the slider 42 and the guide rail 41 ensures the certainty of the movement of the coating section 20 relative to the surface of the object to be coated in the direction of gravity, so that the coating support section 21c on the nozzle 21 is only subject to the rotational constraint of the rotating section 30.

[0043] Please refer to Figures 1 to 5In some embodiments, the nozzle 21 includes a first part 211 and a second part 212 connected to the first part 211. The first part 211 and the second part 212 are arranged in the same direction along the coating direction X. The first part 211 has a first sub-surface 211a and the second part 212 has a second sub-surface 212a. The first sub-surface 211a and the second sub-surface 212a are joined together to form a coating surface 21a. The coating support part 21c is provided on the first sub-surface 211a. In this case, a jet hole 21b is provided on the first sub-surface 211a; or, a jet hole 21b is provided on the second sub-surface 212a.

[0044] Understandably, the first part 211 and the second part 212 are two separable parts of the nozzle 21, that is, one or both can be replaced according to actual usage needs.

[0045] For example, when it is necessary to change the coating thickness of the slurry, the first part 211 of the coating support 21c with different heights can be replaced and combined with the current second part 212 to meet the requirement of changing the coating thickness of the slurry. At the same time, the first part 211 with the coating support 21c is also a wear part. Considering cost issues, it is sufficient to replace only a part of the nozzle 21, without replacing all of the nozzles 21.

[0046] The first sub-surface 211a and the second sub-surface 212a should be kept flush so that the slurry will not interfere with or scratch the first sub-surface 211a or the second sub-surface 212a during the coating process.

[0047] Please refer to Figures 1 to 5 In some embodiments, the first portion 211 has a first wedge-shaped surface 211b connected to the first sub-surface 211a, the first wedge-shaped surface 211b being disposed at an angle to the coating direction X; and / or, The second part 212 has a second wedge-shaped surface 212b connected to the second sub-surface 212a, and the second wedge-shaped surface 212b is set at an angle to the coating direction X.

[0048] Understandably, the wedge-shaped design allows for more clearance between the nozzle 21 and the surface of the object to be coated, thereby reducing the impact of the nozzle 21 on the coated slurry.

[0049] Please refer to Figures 1 to 5 In some embodiments, the coating support 21c includes a support block 21c1 disposed on the first sub-surface 211a; or, The coating support part 21c includes a support block 21c1 disposed on the first sub-surface 211a and an extension block 21c2 disposed on the first wedge-shaped surface 211b, wherein the support block 21c1 and the extension block 21c2 are connected.

[0050] Understandably, depending on actual usage requirements, the coating support 21c may include a support block 21c1, or a support block 21c1 and an extension block 21c2. Here, the extension block 21c2 serves to improve the smoothness of the movement of the support block 21c1 on the surface of the object to be coated.

[0051] Optionally, the connection between the support block 21c1 and the extension block 21c2 is smoothly connected by an arc.

[0052] Please refer to Figures 1 to 5 In some embodiments, the coating section 20 includes a bracket 22 connected to the rotating section 30, a glue valve assembly 23 disposed on the bracket 22, a pressure assembly 24 connected to the glue valve assembly 23, and a nozzle 21 disposed on the glue valve assembly 23, the nozzle 21 being fixedly connected to the bracket 22.

[0053] Secondly, please refer to Figure 6 This application also provides a coating method, implemented using the coating apparatus 100 described above, the coating method comprising the following steps: S001. Select the corresponding nozzle 21 for the coating section 20 according to the slurry coating width and thickness; S002. Perform edge detection on the object to be coated to confirm the coating path, and perform a trial coating operation on the surface of the object to be coated. S003. The angular orientation of the nozzle 21 is adjusted by the rotating part 30 so that the coating surface 21a is parallel to the surface of the object to be coated, until the thickness of the wet film of the slurry coated on the surface of the object to be coated is uniform. S004. The calibrated coating section 20 performs formal coating by moving on the surface of the object to be coated at a preset coating speed.

[0054] The present invention provides a coating method that, based on the coating device 100 described above, makes the entire coating method simpler to operate and enables calibration work to be completed more quickly and intuitively, significantly reducing the reliance on the skills of professional personnel.

[0055] Please refer to Figure 7 In some embodiments, before the formal coating process is performed on the coating unit 20 after calibration, moving at a preset coating speed on the surface of the object to be coated, the coating method further includes: S0031, The coating section 20 can float up and down relative to the surface of the object to be coated in the direction of its own gravity, and the nozzle 21 abuts against the surface of the object to be coated under the action of gravity.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coating apparatus for performing a coating action on the surface of an object to be coated, characterized in that, include: The fixing part is used to connect to the peripheral drive mechanism; The coating section includes a nozzle having a coating surface facing the surface of the object to be coated. The coating surface has spray holes and two coating support portions for abutting against the surface of the object to be coated. These two support portions are spaced apart on opposite sides of the spray holes along a direction perpendicular to the coating direction. A rotating part is provided on the fixed part and connected to the coating part. The extension direction of the rotation center axis of the rotating part is parallel to the coating direction.

2. The coating apparatus according to claim 1, characterized in that: The coating apparatus includes a telescopic part, the telescopic direction of which is perpendicular to the surface of the object to be coated, and the coating part is connected to the rotating part through the telescopic part.

3. The coating apparatus according to claim 2, characterized in that: The rotating part includes a rotating support base connected to the fixed part and a rotating body rotatably connected to the rotating support base about an axis, the rotating body being connected to the telescopic part.

4. The coating apparatus according to claim 3, characterized in that: The rotating part further includes a fine-tuning part, which is disposed on the rotating support base. The rotating body is provided with a force-receiving part that abuts against the fine-tuning part, so that the rotating body rotates relative to the rotating support base around the rotation center axis.

5. The coating apparatus according to claim 2, characterized in that: The telescopic part includes a guide rail connected to the rotating part and a slider connected to the coating part, the slider being slidably connected to the guide rail.

6. The coating apparatus according to any one of claims 1 to 5, characterized in that: The nozzle includes a first part and a second part connected to the first part. The first part and the second part are arranged in the same direction along the coating direction. The first part has a first sub-surface, and the second part has a second sub-surface. The first sub-surface and the second sub-surface are joined together to form the coating surface. The coating support is provided on the first sub-surface. The injection hole is formed on the first sub-surface; or, the injection hole is formed on the second sub-surface.

7. The coating apparatus according to claim 6, characterized in that: The coating support includes a support block disposed on the first sub-surface; or, The first portion has a first wedge-shaped surface connected to the first sub-surface, the first wedge-shaped surface being set at an angle to the coating direction, and the coating support portion including a support block disposed on the first sub-surface and an extension block disposed on the first wedge-shaped surface, the support block being connected to the extension block.

8. The coating apparatus according to any one of claims 1 to 5, characterized in that: The coating section includes a bracket connected to the rotating section, a glue valve assembly disposed on the bracket, a pressure assembly connected to the glue valve assembly, and a nozzle disposed on the glue valve assembly, wherein the nozzle is fixedly connected to the bracket.

9. A coating method, implemented by a coating apparatus as described in any one of claims 1 to 8, characterized in that, The coating method includes the following steps: Select the appropriate nozzle for the coating section based on the width and thickness of the slurry coating; The object to be coated is subjected to edge detection to confirm the coating path, and a trial coating and scraping operation is performed on the surface of the object to be coated. The angular orientation of the nozzle is adjusted by rotating the nozzle so that the coating surface is parallel to the surface of the object to be coated, until the wet film thickness of the slurry coated on the surface of the object to be coated is uniform. The calibrated coating section is then used for formal coating, moving at a preset coating speed on the surface of the object to be coated.

10. The coating method according to claim 9, characterized in that: Before the step of performing formal coating on the calibrated coating section and moving it at a preset coating speed on the surface of the object to be coated, the coating method further includes: The coating section can float up and down relative to the surface of the object to be coated in the direction of its own gravity, and the nozzle abuts against the surface of the object to be coated under the action of gravity.

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