Apparatus and method for preparing superhydrophobic coating on closed metallic curved surface

Abstract

The present invention belongs to the technical field of optical preparation. Disclosed are an apparatus and method for preparing a superhydrophobic coating on a closed metallic curved surface. The apparatus comprises a laser device, a conical concave reflecting mirror, a fixture, a position adjusting platform and a control unit, wherein the fixture is fixed on the position adjusting platform, and the laser device is arranged above the adjusting platform, both the laser device and the position adjusting platform being electrically connected to and controlled by the control unit; the conical concave reflecting mirror is arranged between the fixture and the laser device; the lower base of the conical concave reflecting mirror is sealed, a through hole being provided right in the middle of the lower base; and the laser device is configured to emit laser to the conical concave reflecting mirror, and the conical concave reflecting mirror is configured to reflect and focus the laser. By means of the cooperation of the conical concave reflecting mirror and the laser device, the laser performs rotational scanning around the surface of a closed-curved workpiece, thereby achieving rapid marking; in addition, by dynamically adjusting and controlling a laser scanning path, the preparation of a superhydrophobic coating with high precision, low cost and simple operation is achieved.

Description

Equipment and method for preparing superhydrophobic coatings on closed metal surfaces Technical Field

[0001] This invention relates to an apparatus and method for preparing a superhydrophobic coating, specifically an apparatus and method for preparing a superhydrophobic coating on a closed curved surface of metal, belonging to the field of optical fabrication technology. Background Technology

[0002] Constructing intricate micro / nanostructures on tiny, closed curved metal surfaces has long been a challenging technical problem. For example, hematology analyzer sampling needles are commonly used for blood analysis, including cell counting, hemoglobin determination, and platelet counting. Accurate and representative blood samples are crucial for blood analysis. However, conventional sampling needles easily accumulate blood, requiring frequent replacement and cleaning, a cumbersome process that significantly impacts testing and analysis efficiency and increases the workload of analytical personnel. Superhydrophobic coatings, with their excellent self-cleaning properties, effectively prevent blood adhesion, making them a highly effective solution. The addition of superhydrophobic coatings can greatly reduce the frequency of needle replacement and cleaning. The micro / nanoscale rough structure and low surface energy are key factors in the preparation of superhydrophobic coatings. Traditional methods typically employ laser marking to construct micro / nanostructures on the sampling needle surface. Because the sampling needle has a circular cross-section and a closed, curved surface, it cannot be used for non-rotational marking (referring to the sampling needle itself). Controlling the rotation of the sampling needle while simultaneously using laser marking presents numerous challenges, requiring strict control over the consistency between the needle's rotation axis and the marking direction, while also considering the matching consistency between the needle's rotation speed and the marking speed. Therefore, this marking method may severely affect the precision of the micro / nano structure, directly impacting the actual performance of the final superhydrophobic coating. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a device and method for preparing a high-precision superhydrophobic coating on a closed curved surface while ensuring that the closed curved surface workpiece does not rotate.

[0004] To solve the above-mentioned technical problems, the present invention provides an apparatus for preparing a superhydrophobic coating on a closed curved surface of metal, comprising a laser device, a conical concave mirror, a fixture, a position adjustment platform, and a control unit;

[0005] The clamp is fixed on the position adjustment platform, and the laser device is located above the adjustment platform. Both the laser device and the position adjustment platform are electrically connected and controlled by the control unit.

[0006] The conical concave reflector is positioned between the clamp and the laser device; the bottom of the conical concave reflector is sealed, and a through hole is provided in the center of the bottom;

[0007] The laser device is used to emit laser light onto a conical concave mirror, and the conical concave mirror is used to reflect and focus the laser light.

[0008] The conical concave reflector has a circular or elliptical cross-section.

[0009] The aforementioned apparatus for preparing a superhydrophobic coating on a closed curved metal surface also includes a protective gas supply mechanism for supplying protective gas into the conical concave mirror.

[0010] In this invention, the inner side of the conical concave reflector uses high-quality fused silica as a substrate, and the surface is coated with a high-reflectivity all-dielectric film.

[0011] This invention also provides a method for preparing a superhydrophobic coating on a closed curved surface of metal, using the above-mentioned equipment, specifically including the following steps:

[0012] S1: Fix the closed curved surface workpiece to be processed on the fixture and pass it through the conical concave reflector;

[0013] S2: Keep the central axis of the closed curved surface workpiece to be processed coincident with the central axis of the conical concave mirror;

[0014] S3: Plan the laser scanning path;

[0015] S4: Perform laser scanning on the outside of the closed curved surface workpiece to be processed according to the scanning path determined in S3;

[0016] S5: Perform hydrophobic treatment on the closed curved surface workpiece after S4 processing.

[0017] In this invention, when the cross-section of the closed curved surface workpiece to be processed is circular, the specific process of S3 is as follows:

[0018] S31: Using the central axis of the conical concave mirror with a circular cross-section as the center, draw a circle with radius R to determine the scan line spacing d;

[0019] S32: Determine the descent speed V of the position adjustment platform based on the radius of the circle in S31 and the scanning speed of the laser device. S And the scan end time T.

[0020] In this invention, the time for one laser scan in step S32 is:

[0021] In the formula, R is the radius of the circle, r is the cross-sectional radius of the closed curved surface workpiece to be processed, V1 is the laser scanning speed, and V2 is the scanning speed of the laser relative to the closed curved surface workpiece to be processed.

[0022] In this invention, the formula for the descent speed of the position adjustment platform in S32 is:

[0023] In the formula, ΔS is the scan line spacing.

[0024] In this invention, when the cross-section of the closed curved surface workpiece to be processed is elliptical, the specific process of S3 is as follows:

[0025] S31: Obtain the relationship between the laser-focused workpiece position L3 and the radius of the trajectory circle:

[0026] In the formula, L is the focal length, Q is the distance from any point on the ellipse to the workpiece, θ' is the cone angle of the frustum, and θ 1-4 L1 is the optical path auxiliary angle, L2 is the distance from the light source to the mirror, L2 is the distance from the light source reflected by the mirror to the workpiece surface, and r is the cross-sectional radius of the closed curved surface workpiece to be processed.

[0027] Measure the length of the major semi-axis 'a' and the length of the minor semi-axis 'b' of the ellipse of the closed curved surface workpiece to be processed, and draw the figure with the minor semi-axis length as... The length of the major semi-axis is The ellipse is drawn with the central axis of the conical concave mirror with an elliptical cross-section as the center, and a circle with radius R is drawn to determine the scan line spacing d; A is the length of the minor semi-axis of the ellipse drawn by the software, and B is the length of the major semi-axis of the ellipse drawn by the software.

[0028] S32: Determine the descent speed V of the position adjustment platform based on the radius of the circle in S31 and the scanning speed of the laser device. S And the scan end time T.

[0029] In this invention, the time for one laser scan in S32 is:

[0030] In the formula, A is the length of the minor semi-axis of the ellipse drawn by the software, B is the length of the major semi-axis of the ellipse drawn by the software, V1 is the laser scanning speed, V2 is the scanning speed of the laser relative to the closed curved surface workpiece to be processed, a is the length of the major semi-axis of the closed curved surface workpiece to be processed, and b is the length of the minor semi-axis of the closed curved surface workpiece to be processed.

[0031] In this invention, the formula for the descent speed of the position adjustment platform in S32 is as follows:

[0032] In the formula, ΔS is the scan line spacing.

[0033] The beneficial effects of the present invention are as follows: (1) By combining the conical concave reflector with the laser device, the laser rotates and scans around the surface of the closed curved workpiece to achieve rapid marking, and by dynamically controlling the laser scanning path, a high-precision, low-cost, and easy-to-operate superhydrophobic coating can be prepared; (2) Compared with the traditional method of preparing superhydrophobic coatings on closed curved surfaces by electrochemical means (i.e., placing them in an electrolyte to etch a rough surface structure), the present invention uses laser rotation scanning to prepare superhydrophobic sampling needles, which can significantly save time and improve preparation efficiency; (3) According to the conversion ratio of V1 to V2, the method of preparing superhydrophobic sampling needles using laser rotation scanning in the present invention can achieve faster laser scanning speed marking; (4) It avoids the horizontal placement and rotation of the closed curved workpiece, and performs three-dimensional modeling and marking of the closed curved workpiece, simplifying the scanning method and increasing the marking accuracy; (5) Providing protective gas to the conical concave reflector during marking can, to a certain extent, avoid oxidation reaction during the marking process. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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.

[0035] Figure 1 is a schematic diagram of the equipment structure for preparing superhydrophobic coatings on closed curved surfaces of metal.

[0036] Figure 2 shows the circular scanning path diagram drawn by the computer control system.

[0037] In the diagram, 1-laser device, 2-lifting platform, 3-micrometer precision fine-tuning platform slide, 4-clamp, 5-conical concave reflector, 6-sampling needle, 7-computer control system, 8-protective gas unit. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0040] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. 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, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0044] As shown in Figure 1, the apparatus for preparing a superhydrophobic coating on a closed curved surface of metal provided in this embodiment includes a laser device 1, a lifting platform 2, a micrometer precision adjustment platform slide 3, a clamp 4, a conical concave mirror 5, a sampling needle 6, a computer control system 7, and a protective gas unit 8. The micrometer precision adjustment platform slide 3 is fixedly mounted on the lifting platform 2, and the lower end of the clamp 4 is fixedly mounted on the micrometer precision adjustment platform slide 3. The clamp 4 is used to fix the sampling needle 6.

[0045] The lifting platform 2 uses a lead screw to control its lifting. The stepper motor in the lifting platform 2 is connected to a motor interface adapter, which is connected to a computer control system 7 and is ultimately controlled by the computer control system 7. The lifting platform 2 is existing technology.

[0046] The laser device 1 is fixedly mounted above the fixture 4, and is electrically connected to and controlled by the computer control system 7. The conical concave reflector 5 is suspended between the fixture 4 and the laser device 1.

[0047] In this embodiment, the inner side of the conical concave mirror 5 uses high-quality fused silica as a substrate, and the surface is coated with a high-reflectivity all-dielectric film; the cross-section of the conical concave mirror 5 is circular. The bottom of the conical concave mirror 5 is a sealed structure, and a through hole is opened in the center of the bottom for the sampling needle 6 to pass through. In this embodiment, the taper of the concave mirror 5 is 1.155, the diameter of the upper bottom circle is 39.1 mm, the diameter of the lower bottom circle is 16 mm, and the height is 20 mm.

[0048] The sampling needle 6 is fixed in the clamp 4, and the upper part of the sampling needle 6 passes through the conical concave reflector 5.

[0049] In this embodiment, the computer control system 7 generates the path and position information of the laser beam and controls the laser device 1 to generate a Gaussian laser source. The laser beam passes through the grating, beam expander, galvanometer and focusing lens in the laser device 1 in sequence and irradiates the conical concave mirror 5. The conical concave mirror 5 then focuses the light onto the surface of the sampling needle 6.

[0050] A protective gas unit 8 is disposed above the conical concave reflector 5 and is used to supply protective gas into the concave concave reflector 5. The protective gas unit 8 is electrically connected to and controlled by the computer control system 7. The protective gas unit 8 can be implemented using a protective gas supply mechanism commonly used in the prior art, and will not be described in detail here. In this embodiment, the protective gas unit 8 uses a mixed inert protective gas (80% Ar + 20% CO2).

[0051] In this embodiment, the micrometer precision adjustment platform slide 3 is a screw-groove mechanism, which can be freely adjusted in the xy plane. After determining the laser focal point, the xy information is fed back to the host, and this position is positioned as the starting point. After changing the sampling needle 6, it can return to the starting point. The micrometer precision adjustment platform slide 3 ensures that the sampling needle 6 is located at the center of the conical concave mirror 5 and that the midpoint of the circular path coincides with the center of the conical concave mirror 5. The micrometer precision adjustment platform slide 3 is existing technology.

[0052] In this embodiment, the sampling needle 6 is a Sysmex hematology analyzer sampling needle 6, which is made of SUS316I stainless steel. The sampling needle 6 has a radius r of 1 mm and a length L of 200 mm.

[0053] In this embodiment, laser device 1 is a Q-switched pulsed fiber laser RFL-P20QE developed by Raycus Laser, with an average output power of 20W, a pulse width of 120ns, and an operating temperature of 0~40℃; the galvanometer in laser device 1 is model ST8161Y, with a maximum scanning angle of ±20°, a small step response time of 0.45ms, and a maximum zero drift of 10μRad; the focusing lens in laser device 1 adopts a fully optically coated lens, K9 (H-K9L, N-BK7) optical material, and a light transmittance of 99.1%.

[0054] The preparation process of the superhydrophobic coating in this embodiment is as follows:

[0055] 1. Cleaning and pretreatment: Use a micrometer and vernier caliper to measure the radius r and length L of the sampling needle 6 respectively; clean the sampling needle 6 by ultrasonic vibration in alcohol and deionized water for 10-40 minutes, then take it out and place it upside down in a drying oven for 30-60 minutes.

[0056] 2. Positioning: After removing the sampling needle 6 from the drying oven, control the lifting platform 2 to lower to the lowest position. Use the clamp 4 to firmly clamp the fixing sleeve of the sampling needle 6. The upper part of the sampling needle 6 passes through the conical concave reflector 5. The distance between the lowest position of the lifting platform 2 and the lower end of the conical concave reflector 5 is 220mm. Adjust the micrometer precision fine adjustment platform slide 3 so that the central axis of the sampling needle 6 coincides with the central axis of the conical concave reflector 5. After positioning, input the signal through the computer control system 7 to raise the lifting platform 2 to the scanning start position. The scanning start position is 1mm from the tail of the sampling needle 6 to the lower end of the conical concave reflector 5.

[0057] 3. Scanning parameter settings: In the computer control system 7, set the laser distance to the marking plane to 200mm, the scanning speed vd to 3000mm / s, the spot diameter to 1μm, the frequency μ to 30kHz, and the power P to 5W.

[0058] 4. As shown in Figure 2, scanning path planning: Using ezcad software in the computer control system 7, draw a circle with radius R centered on the central axis of the conical concave reflector 5, determine the laser scanning line spacing d, and calculate the descent speed V of the lifting platform 2 based on the radius of the circle and the scanning speed. s The scanning end time T is as follows: the focal length of the laser in laser device 1 is 250mm; the radius R of the circle is 12mm; the scanning line spacing ΔS is 5μm; and the scanning time T is 40s.

[0059] Let the time for one laser scan be:

[0060] In equation (1), R is the radius of the circle, r is the cross-sectional radius of the sampling needle, V1 is the laser scanning speed, and V2 is the laser scanning speed relative to the surface of the sampling needle.

[0061] Let the formula for the descent speed of lifting platform 2 be:

[0062] In equation (2), ΔS is the scan line spacing.

[0063] 5. Laser Scanning Process: The laser device emits a Gaussian beam with a Rayleigh range of 0.5 mm. The Gaussian beam passes through a grating and a beam expander and illuminates the galvanometer. The computer control system 7 sends a signal to the drive amplifier circuit, which drives the galvanometer to swing and scan along a preset circular path. After passing through a focusing lens, the beam illuminates the conical concave mirror 5 and is finally reflected and focused onto the surface of the sampling needle 6. At this time, the pneumatic valve in the protective gas unit 8 receives a current signal from the computer control system 7 and opens the pneumatic valve, sending protective gas into the space of the conical concave mirror 5. Since the laser marking of the sampling needle 6 will ablate the metal surface in a short time, causing oxidation to a certain extent, this embodiment selects a mixed inert protective gas, which is placed above the laser focal point and continuously supplied to the conical concave mirror 5 under the control of the computer control system 7. Under these process parameters for fabricating superhydrophobic materials, the metal interface will oxidize, causing it to turn black. This not only affects the aesthetics, but the oxides will also affect the mechanical properties of the metal surface. Therefore, in this embodiment, adding a protective gas can prevent oxidation and protect the metal surface from excessive ablation.

[0064] Simultaneously, the lifting stepper motor in the lifting platform 2 receives a current signal from the computer control system 7, in the form of V... s The speed decreases, and a micro-nano dual-scale structure is etched on the surface of the sampling needle 6.

[0065] 6. Superhydrophobic treatment: After the laser scanning is complete, release the clamp 4, remove the sampling needle 6, and perform silanization treatment on the sampling needle 6 using the immersion method for 1-5 minutes. Remove and dry to form a superhydrophobic coating on the surface of the sampling needle 6.

[0066] This embodiment describes the technical solution of the present invention in detail using a sample with a circular cross-section. The technical solution of this embodiment is also applicable to the preparation of superhydrophobic coatings on other metal closed curved surface workpieces with elliptical cross-sections.

[0067] When preparing superhydrophobic coatings on other closed curved metal workpieces with elliptical cross-sections, the scanning path needs to be replanned. The circle in this embodiment needs to be changed to an ellipse, and the shape of the drawn ellipse needs to be adjusted accordingly, or the shape of the conical concave reflector needs to be changed from a frustum of a cone to a frustum of an ellipse. Figure 3 shows a simplified laser path diagram. The relationship between the laser-focused workpiece position L3 and the radius of the trajectory circle can be calculated by solving the following equation:

[0068] In the formula, L is the focal length, Q is the distance from any point on the ellipse to the workpiece, θ' is the cone angle of the frustum, and θ 1-4 L1 is the optical path auxiliary angle, L2 is the distance from the light source to the mirror, L3 is the distance from the light source reflected by the mirror to the workpiece surface, and r is the cross-sectional radius of the sampling needle.

[0069] The ellipse shape is adjusted accordingly, and the specific implementation plan is as follows: As shown in Figure 3, the workpiece radius and the trajectory radius satisfy the following relationship:

[0070] Measure the length of the major semi-axis 'a' and the length of the minor semi-axis 'b' of the ellipse of the closed curved surface workpiece to be processed, and draw the figure with the minor semi-axis length as... The length of the major semi-axis is The ellipse is drawn with the central axis of the conical concave mirror with an elliptical cross-section as the center, and a circle with radius R is drawn to determine the scan line spacing d; A is the length of the minor semi-axis of the ellipse drawn by the software, and B is the length of the major semi-axis of the ellipse drawn by the software. Based on this, the content described in step 4 above is repeated, as shown in Figure 4. The time for one laser scan in step 4 is:

[0071] In the formula, A is the length of the minor semi-axis of the ellipse drawn by ezcad software, B is the length of the major semi-axis of the ellipse drawn by ezcad software, V1 is the laser scanning speed, V2 is the scanning speed of the laser relative to the closed curved surface workpiece to be processed, a is the length of the major semi-axis of the closed curved surface workpiece to be processed, and b is the length of the minor semi-axis of the closed curved surface workpiece to be processed.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for preparing a superhydrophobic coating on a closed curved surface of metal, characterized in that: Includes a laser device, a concave reflector, a fixture, a position adjustment platform, and a control unit; The clamp is fixed on the position adjustment platform, and the laser device is located above the adjustment platform. Both the laser device and the position adjustment platform are electrically connected and controlled by the control unit. The conical concave reflector is positioned between the clamp and the laser device; the bottom of the conical concave reflector is sealed, and a through hole is provided in the center of the bottom; The laser device is used to emit laser light onto a conical concave mirror, and the conical concave mirror is used to reflect and focus the laser light. The conical concave reflector has a circular or elliptical cross-section.

2. The apparatus for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 1, characterized in that: It also includes a protective gas supply mechanism for supplying protective gas into the concave concave mirror.

3. The apparatus for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 1 or 2, characterized in that: The inner side of the conical concave mirror uses high-quality fused silica as a substrate, and the surface is coated with a high-reflectivity all-dielectric film.

4. A method for preparing a superhydrophobic coating on a closed curved surface of metal, characterized in that: Using the device according to claim 1, the steps include: S1: Fix the closed curved surface workpiece to be processed on the fixture and pass it through the conical concave reflector; S2: Keep the central axis of the closed curved surface workpiece to be processed coincident with the central axis of the conical concave mirror; S3: Plan the laser scanning path; S4: Perform laser scanning on the outside of the closed curved surface workpiece to be processed according to the scanning path determined in S3; S5: Perform hydrophobic treatment on the closed curved surface workpiece after S4 processing.

5. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 4, characterized in that, When the cross-section of the closed curved surface workpiece to be processed is circular, the specific process of S3 is as follows: S31: Using the central axis of the conical concave mirror with a circular cross-section as the center, draw a circle with radius R to determine the scan line spacing d; S32: Determine the descent speed V of the position adjustment platform based on the radius of the circle in S31 and the scanning speed of the laser device. S And the scan end time T.

6. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 5, characterized in that, The time for one laser scan in S32 is: In the formula, R is the radius of the circle, r is the cross-sectional radius of the closed curved surface workpiece to be processed, V1 is the laser scanning speed, and V2 is the scanning speed of the laser relative to the closed curved surface workpiece to be processed.

7. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 5, characterized in that, The formula for the descent speed of the position adjustment platform in S32 is: In the formula, ΔS is the scan line spacing.

8. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 4, characterized in that, When the cross-section of the closed curved surface workpiece to be processed is elliptical, the specific process of S3 is as follows: S31: Obtain the relationship between the laser-focused workpiece position L3 and the radius of the trajectory circle: In the formula, L is the focal length, Q is the distance from any point on the ellipse to the workpiece, θ' is the cone angle of the frustum, and θ 1-4 L1 is the optical path auxiliary angle, L2 is the distance from the light source to the mirror, L2 is the distance from the light source reflected by the mirror to the workpiece surface, and r is the cross-sectional radius of the closed curved surface workpiece to be processed. Measure the length of the major semi-axis 'a' and the length of the minor semi-axis 'b' of the ellipse of the closed curved surface workpiece to be processed, and draw the figure with the minor semi-axis length as... The length of the major semi-axis is The ellipse is drawn with the central axis of the conical concave mirror with an elliptical cross-section as the center, and a circle with radius R is drawn to determine the scan line spacing d; A is the length of the minor semi-axis of the ellipse drawn by the software, and B is the length of the major semi-axis of the ellipse drawn by the software. S32: Determine the descent speed V of the position adjustment platform based on the radius of the circle in S31 and the scanning speed of the laser device. S And the scan end time T.

9. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 8, characterized in that, The time for one laser scan in S32 is: In the formula, A is the length of the minor semi-axis of the ellipse drawn by the software, B is the length of the major semi-axis of the ellipse drawn by the software, V1 is the laser scanning speed, V2 is the scanning speed of the laser relative to the closed curved surface workpiece to be processed, a is the length of the major semi-axis of the closed curved surface workpiece to be processed, and b is the length of the minor semi-axis of the closed curved surface workpiece to be processed.

10. The method for preparing a superhydrophobic coating on a closed curved surface of metal according to claim 8, characterized in that, The formula for the descent speed of the position adjustment platform in S32 is: In the formula, ΔS is the scan line spacing.

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