Conical filter forming method for aerospace equipment and conical filter

Abstract

This invention provides a method for forming a cone-shaped filter suitable for aerospace equipment, and the cone-shaped filter itself. The forming method includes: Step S1: cutting a multi-layer stainless steel filter mesh into a fan shape; Step S2: welding the periphery of the fan-shaped filter mesh to seal the edges; Step S3: performing surface heat treatment on the filter mesh, and using spinning or rolling progressive forming to roll the filter mesh into a cone shape, followed by quality inspection and strengthening treatment; Step S4: trial assembly of the filter mesh with the top cap and base; Step S5: welding the longitudinal seam of the filter mesh; Step S6: welding the transverse seam between the filter mesh and the top cap and base. This invention can solve the problems of poor forming accuracy, weak resistance to high temperature and high pressure, weak corrosion resistance, large characteristic dimension detection error, and low efficiency of cone-shaped filters with large aspect ratios in aerospace pressurized delivery systems. The cone-shaped filter obtained by the method of this invention can meet the various technical requirements of pressurized delivery systems, such as flow area and filtration accuracy.

Description

Technical Field

[0001] This invention relates to the field of aerospace equipment technology, specifically to a method for forming a cone-shaped filter suitable for aerospace equipment and a cone-shaped filter, and more particularly to a method for forming a cone-shaped filter product with a large aspect ratio for the liquid path of a rocket pressurization and delivery system. Background Technology

[0002] As the performance requirements of new-generation high-thrust cryogenic rockets continue to increase, the standards for foreign matter control in the pressurization and delivery system's fluid circuits are also showing a significant upward trend. Installing high-precision filters in the rocket's fluid circuits has become a crucial measure. When pressurized gas drives the rocket propellant to flow through the fluid circuit, this filter can effectively filter and remove any foreign matter that may be present in the propellant, thereby ensuring that the cleanliness of the propellant used in downstream engines meets aerospace technical standards, providing a solid guarantee for the stable and efficient operation of the rocket engine.

[0003] Therefore, the development and production process of high-thrust cryogenic rockets has placed new demands on filters that combine high flow rates and high filtration accuracy. Traditional 10µm-class filters are no longer sufficient to meet the stringent requirements for filtration accuracy, necessitating the development of new 1-2µm-class filters. However, with the rapid reduction in filter pore size and the substantial increase in filtration flow rate, the fluid pressure exerted on the filter increases exponentially, thus placing even more stringent requirements on the filter's material, rigidity, and strength.

[0004] Currently, high aspect ratio cone filters can better adapt to the strength and stiffness requirements under new conditions. To ensure both filtration accuracy and flow rate while meeting pipeline diameter requirements, they are typically manufactured by directly forming them into a cone shape using stamping dies. However, for high aspect ratio filter screens, due to the high strength of the screen material itself, direct stamping results in significant deformation of the upper mesh openings, potentially leading to wire breakage and failing to meet filtration accuracy requirements. Furthermore, the high-strength screen material is prone to burrs during production. In summary, current aerospace-grade high aspect ratio cone filters suffer from poor forming accuracy, weak resistance to high temperatures and pressures, poor corrosion resistance, large errors in characteristic dimension detection, and low efficiency, failing to meet the demands of aerospace applications.

[0005] Therefore, there is an urgent need for a method for forming a cone-shaped filter with a large aspect ratio for aerospace applications, so that the formed cone-shaped filter can meet the requirements of various technical indicators such as flow area and filtration accuracy. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for forming a cone-shaped filter and a cone-shaped filter suitable for aerospace equipment.

[0007] A method for forming a cone-shaped filter suitable for aerospace equipment according to the present invention includes: Step S1: Cut the stainless steel multi-layer filter mesh into a fan shape; Step S2: Seal the perimeter of the welded fan-shaped filter screen; Step S3: Perform surface heat treatment on the filter screen, and roll the filter screen into a cone shape using spin forming or roll forming progressive forming. After forming, perform quality inspection and strengthening treatment. Step S4: Test assemble the filter screen with the top cap and base; Step S5: Weld the longitudinal seams of the filter screen; Step S6: Weld the filter screen to the top cap and the horizontal seam of the base.

[0008] Preferably, during the welding process in step S2, the multi-layer filter screen is positioned between layers, and the interlayer positioning method is as follows: Multiple layers of mesh are fixed using permanent magnets or electromagnetic chucks to ensure an alignment accuracy of less than or equal to 0.05 mm. At the same time, an optical alignment system is used, employing an industrial camera and image recognition software to automatically correct interlayer misalignment.

[0009] Preferably, the welding method in step S2 is: vacuum diffusion welding; the temperature is 1050-1150℃ for stainless steel materials and 850-950℃ for titanium alloy materials, the pressure is 5-15MPa, the holding time is 1-4 hours, and the vacuum degree is ≤1×10⁻³Pa.

[0010] Preferably, the spinning forming method includes: using the spindle of a spinning machine to drive the fan-shaped filter blank to rotate, and applying radial pressure through rollers to gradually conform it to the molding mold to form a conical surface; The process parameters used are a rotation speed of 200-500 rpm, a feed speed of 0.5-2 mm / rad, and progressive forming in 3-5 passes. The roller pressure is 50-200 MPa, and the roller pressure increases with the increase of the cone angle.

[0011] Preferably, the progressive rolling forming method includes: progressively bending the filter screen along the generatrix of the conical surface using a three-roll symmetrical rolling mill, and controlling the taper by adjusting the roller spacing and inclination angle; the roller taper is 0-30 degrees, and the roller position is adjusted in real time by a CNC system; the initial roller gap is 1.1 times the filter screen thickness, decreasing by 0.1-0.2 mm per pass, the bending angle increases by 2-5 degrees per pass, and the total number of passes = target cone angle / single increment.

[0012] Preferably, before spin forming or roll forming, the filter screen undergoes surface heat treatment, including: cleaning and surface treatment, furnace loading and fixing, solution treatment, aging strengthening, and passivation treatment. The cleaning and surface treatment are used to remove oil and oxides from the filter screen surface and to check for processing defects. The filter screen is fixed using a high-temperature resistant clamp during furnace loading. The solution treatment method is as follows: heat to 1040±10℃, hold for 1 hour, and then quickly cool with water or oil to form supersaturated martensite. The key point is to prevent the precipitation of σ phase during the cooling process. The aging strengthening method is as follows: heat to 480~620℃, hold for 4 hours, air cool to room temperature, precipitate copper-rich strengthening phase, and achieve a hardness of HRC40~45. The passivation treatment method is: immersion in nitric acid solution to enhance corrosion resistance.

[0013] Preferably, the quality inspection in step S3 includes geometric accuracy inspection and pore integrity assessment; The geometric accuracy detection employs color laser confocal microscopy scanning measurement, combined with high-precision point cloud filtering and feature extraction algorithms.

[0014] Preferably, the point cloud filtering algorithm employs a statistical filtering algorithm to remove outliers for each point. p i Calculate its neighborhood k Average distance of points d i : The global mean and standard deviation are: , Remove For the points, α is the threshold coefficient; after removing outliers, for the remaining 3D point cloud data, the cone surface equation in the CAD model is used. The z-value is calculated from the x and y coordinates of the point cloud. This value is compared with the z-coordinate of the point cloud; the error is ≤0.1mm. It is the design half-cone angle of the conical surface; The feature extraction algorithm uses normal vector estimation to calculate the surface normal vector of the point cloud. p i Calculate its neighborhood covariance matrix C: ,in ; Perform eigenvalue decomposition on C: , For each eigenvalue, the eigenvector corresponding to the smallest eigenvalue is... That is, the normal vector. Based on the normal vector... Vector of the filter axis Obtain the calculated value of the half-cone angle. Filter axis vector The clamps of the confocal micrometer are collinear, and this vector is directly provided by the instrument; compare with the design value of the half-cone angle. and measured calculated values The error must be ≤0.1°.

[0015] Preferably, the pore integrity assessment uses a camera with backlight illumination, combined with image processing algorithms to measure the pore diameter and pore spacing, allowing a maximum deformation of 5%; The image processing algorithm uses Gaussian filtering to smooth the image and suppress noise. The calculation formula is as follows: Gradient calculation: The Sobel operator is used to calculate the gradient magnitude G and direction. , , Non-maximum suppression preserves local maxima along the gradient direction, refines edges, and preserves weak edges if they are connected to strong edges.

[0016] According to the present invention, a cone-shaped filter is manufactured using the cone-shaped filter molding method suitable for aerospace equipment.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention can solve the problems of poor molding accuracy, weak resistance to high temperature and high pressure, weak corrosion resistance, large error in characteristic dimension detection, and low efficiency of cone filters with large aspect ratio in aerospace pressurization and delivery systems. The cone filter obtained by the method of this invention can meet the technical requirements of pressurization and delivery systems, such as flow area and filtration accuracy. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram showing the reserved sealing edge size of the fan-shaped stainless steel filter screen in this invention; Figure 2 This is a schematic diagram illustrating the cone-shaped filter curling process in this invention; Figure 3 This is an exploded view of the filter product in this invention; Figure 4 This is a flowchart of the cone-shaped filter forming method in this invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0020] This invention provides a method for molding a high aspect ratio cone-shaped filter for aerospace applications, referring to... Figures 1 to 4 As shown, the method includes: Step S1: Cut the stainless steel multi-layer filter mesh into a fan shape; Step S2: Seal the perimeter of the welded fan-shaped filter screen; Step S3: Roll the filter screen into a cone shape using spinning or rolling progressive forming; Step S4: Test assemble the filter screen with the top cap and base; Step S5: Weld the longitudinal seams of the filter screen; Step S6: Weld the filter screen to the top cap and the horizontal seam of the base.

[0021] In one specific embodiment, step S1 includes: processing the stainless steel multi-layer filter screen into a fan shape using a cutting method, the size of which should be calculated according to the unfolded diagram of the cone filter. A high-hardness alloy blade (such as SKD11) is used for cutting, and the blade gap is adjusted to 5%-8% of the filter screen thickness (e.g., 0.1mm gap corresponds to 2mm thickness). A vacuum adsorption table or magnetic clamp is used for fixing to prevent the filter screen from slipping; simultaneously, pressure plates are added to both sides of the cutting line to reduce wavy deformation caused by shearing force. After cutting, the fan-shaped filter screen requires deburring and edge strengthening post-cutting treatment methods, including: mechanical polishing using a nylon brush wheel (2000rpm) to remove microburrs; or electrolytic polishing using 40% phosphoric acid + 30% sulfuric acid + 30% water at a temperature of 50 degrees Celsius, a current density of 20a / dm³, and a time of 3-5 minutes.

[0022] Edge reinforcement is achieved through a rolling process, where hydraulic rollers apply pressure (50-100 MPa) to the cut edges to improve fatigue resistance. Simultaneously, a protective coating is applied, consisting of an epoxy zinc-rich primer (20-30 μm thick) to prevent chloride ion corrosion.

[0023] The fan-shaped filter screen mentioned in step S1 is an assembly of multiple layers of filter screens with different pore sizes. It is fixed by welding. After sealing, its size should be expanded outward by 1.5mm. Finally, the final cone shape is completed by spinning or rolling progressive molding.

[0024] The interlayer positioning and surface pretreatment of the multi-layer filter screen include: using precision stacked magnetic tooling to fix the multi-layer mesh with permanent magnets or electromagnetic chucks to ensure an alignment accuracy of less than or equal to 0.05 mm; and using an optical alignment system with an industrial camera and image recognition software (such as Halcon) to automatically correct interlayer misalignment. During surface pretreatment, plasma cleaning is used to remove oil and oxide layers, improving interlayer wettability (contact angle <10°). Sandblasting with Al2O3 abrasive particles (50 μm diameter) is then applied to increase surface area and enhance bonding strength.

[0025] In step S2, the welding method and process parameters include: vacuum diffusion welding, where atoms diffuse across the interface under high temperature (0.7-0.9Tm) and high pressure to achieve solid-state metallurgical bonding. The temperature for stainless steel is 1050-1150℃, and the temperature for titanium alloy is 850-950℃. The pressure is 5-15MPa, the holding time is 1-4 hours, and the vacuum degree is ≤1×10⁻³Pa.

[0026] The spinning forming method includes: using the spindle of a spinning machine to drive the fan-shaped filter screen blank to rotate, and applying radial pressure through rollers to gradually conform it to the forming mold to form a conical surface; the process parameters used are: rotation speed of 200-500 rpm (low speed for stainless steel filter screens, high speed for titanium alloys), feed speed of 0.5-2 mm / rad, forming in 3-5 passes, and roller pressure of 50-200 MPa (increasing with the increase of the cone angle); The spinning die is made of cemented carbide material. Before forming, the die is preheated to 150-200 degrees Celsius to reduce work hardening. At the same time, molybdenum disulfide lubricant is sprayed to reduce the surface friction coefficient (u<0.1). The progressive rolling forming method includes: using a three-roll symmetrical rolling mill to progressively bend the filter screen along the generatrix of the conical surface, and controlling the taper by adjusting the roller spacing and inclination angle; the roller taper is adjustable (0-30 degrees), and the CNC system adjusts the roller position in real time (positioning accuracy ±0.05mm); the process parameters used are: the roller gap (initial gap) is 1.1 times the filter screen thickness, decreasing by 0.1-0.2mm per pass, the bending angle increasing by 2-5 degrees per pass, and the total number of passes = target cone angle / single increment.

[0027] For both spinning and roll forming methods, the filter screen surface needs to be heat treated before forming to ensure that the filter screen material has high heat resistance, oxidation resistance, creep resistance and excellent mechanical properties. Specific heat treatments for filter screen surfaces include: cleaning and surface treatment, furnace loading and fixing, solution treatment, aging strengthening, and passivation treatment.

[0028] Cleaning and surface treatment are used to remove oil and oxides from the filter screen surface and to check for processing defects. When fixing the filter screen in the furnace, high-temperature resistant clamps are used to fix the filter screen to avoid heating deformation and to ensure that the filter screen is heated evenly (spacing ≥ 50mm).

[0029] The solution treatment method is as follows: heat to 1040±10℃, hold for 1 hour, and then quickly cool with water or oil to form supersaturated martensite. The key point is to prevent the precipitation of σ phase during the cooling process.

[0030] The aging strengthening method is as follows: heat to 480~620℃, hold for 4 hours (select the temperature according to the hardness requirement), air cool to room temperature, copper-rich strengthening phase is precipitated, and the hardness reaches HRC 40~45.

[0031] The passivation treatment method is: immersion in nitric acid solution to enhance corrosion resistance.

[0032] After using spin forming or roll forming, quality inspection and strengthening treatments such as geometric accuracy testing and pore integrity assessment are required.

[0033] Specifically, geometric accuracy testing differs from conventional contact measurement methods. Due to the large number of measurement features on the filter screen and its sensitivity to external forces, color laser confocal microscopy is used for measurement, combined with high-precision point cloud filtering and feature extraction algorithms. Compared with the CAD model, the cone surface profile error is ≤0.1mm and the cone angle error is ≤0.1°. In one specific implementation, the point cloud filtering algorithm employs a statistical filtering algorithm to remove outliers for each point. p i Calculate its neighborhood k Average distance of points d i : The global mean and standard deviation are: , Remove point ( (Threshold coefficient); After removing outliers, for the remaining 3D point cloud data, based on the cone surface equation in the CAD model... The z-value is calculated from the x and y coordinates of the point cloud. This value is compared with the z-coordinate of the point cloud; the error is ≤0.1mm. It is the design half-cone angle of the conical surface; In one specific implementation, the feature extraction algorithm employs normal vector estimation to calculate the surface normal vector of the point cloud. p i Calculate its neighborhood covariance matrix C: ,in Perform eigenvalue decomposition on C: , For each eigenvalue, the eigenvector corresponding to the smallest eigenvalue is... That is, the normal vector. Based on the normal vector... Vector of the filter axis Obtain the calculated value of the half-cone angle. Due to the centering clamping during the measurement process, the filter axis vector The clamps are collinear with the confocal micrometer's fixture, therefore this vector is directly provided by the instrument. Compare this to the designed half-cone angle value. and measured calculated values The error must be ≤0.1°.

[0034] In one specific implementation, the pore integrity assessment requires integrity testing of each product to avoid errors and inefficiencies from manual visual inspection. A high-resolution camera with backlighting is used, combined with image processing algorithms (such as edge detection) to measure the pore diameter and pore spacing, allowing a maximum deformation of 5%. The pressure drop test is performed according to ISO 3966 standard, with a pressure drop deviation of less than or equal to 10% at a flow rate of 30 m³ / h. Specifically, the image processing algorithm is a high-precision, low-noise edge detection method that uses Gaussian filtering to smooth the image and suppress noise. The calculation formula is as follows: Gradient calculation: The Sobel operator is used to calculate the gradient magnitude G and direction. , , Non-maximum suppression preserves local maxima along the gradient direction (e.g., 0°, 45°, 90°, 135°), refines edges, and preserves weak edges if they are connected to strong edges.

[0035] In one specific embodiment, the strengthening treatment employs shot peening with steel shot of 0.2 mm diameter and 200% coverage, which increases fatigue strength by 30%. Chemical passivation involves immersing the steel shot in a 20% nitric acid + 2% hydrofluoric acid solution for 20 minutes to improve corrosion resistance. Before step S3, progressive forming production by spinning or rolling should be completed. The dimensions of the template should conform to the theoretical inner wall dimensions of the filter screen. When producing the cone-shaped filter screen, the outer dimensions of the template are used to form the sheet metal of the filter screen.

[0036] In step S4, the filter screen is trial-assembled with the top cap and base to prevent welding failure due to abnormal part dimensions.

[0037] During longitudinal seam welding in step S5, the weld reinforcement height is 1mm~2mm, and the weld is uniform.

[0038] During the horizontal seam welding in step S6, a quick clamping device is used to clamp the entire flange ring to the plate. When welding, the quick clamping device at the corresponding welding position is removed and welded. After welding this section, the quick clamping device is immediately clamped in its original position to prevent welding deformation.

[0039] During the welding of longitudinal and transverse seams, the treatment of the filter screen surface before welding, the selection of welding methods, fixtures and positioning, process parameters, process control, and post-weld treatment and inspection are all important aspects. Before welding, the filter screen surface needs to be treated to clean oil and oxides from the welding area (e.g., acetone or alcohol for stainless steel). For fine filter screens, protective tape can be used to cover non-welding areas to prevent spatter from clogging the mesh. TIG welding (tungsten inert gas welding) is used during welding, which has a small heat-affected zone and allows for control of the penetration depth, making it suitable for stainless steel or high-precision filter screens. During welding, a special fixture is used to fix the cone and filter screen to ensure alignment and avoid welding misalignment. Segmented welding (skip welding method) is used to disperse heat and reduce local deformation. Low current and short arc operation are used during welding to reduce heat input and prevent the filter screen from burning through or deforming. Argon or mixed gas protection is used to prevent oxidation (especially for stainless steel and titanium alloys). To prevent welding deformation, a symmetrical welding sequence is used during welding to balance stress. For thin-walled cones, pre-applied anti-deformation amount or post-weld straightening is applied.

[0040] When welding, keep away from the filter area or use a copper backing to absorb heat, and prioritize spot welding or intermittent welding; ensure full penetration and avoid defects such as incomplete fusion and porosity (which can be checked by penetrant testing or X-ray inspection). After welding, clean the weld slag and polish the weld area. Post-weld treatment and inspection include acid pickling and passivation (for stainless steel) to restore corrosion resistance; sandblasting or electrolytic polishing to improve surface finish; finally, pressure testing to check weld sealing; and flow / filtration testing to verify whether the filter screen is clogged or has changed pore size due to welding.

[0041] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "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 application 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 application.

[0042] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for forming a cone-shaped filter suitable for aerospace equipment, characterized in that, include: Step S1: Cut the stainless steel multi-layer filter mesh into a fan shape; Step S2: Seal the perimeter of the welded fan-shaped filter screen; Step S3: Perform surface heat treatment on the filter screen, and roll the filter screen into a cone shape using spin forming or roll forming progressive forming. After forming, perform quality inspection and strengthening treatment. Step S4: Test assemble the filter screen with the top cap and base; Step S5: Weld the longitudinal seams of the filter screen; Step S6: Weld the filter screen to the top cap and the horizontal seam of the base.

2. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, During the welding process in step S2, the multi-layer filter screen is positioned between layers. The interlayer positioning method is as follows: Multiple layers of mesh are fixed using permanent magnets or electromagnetic chucks to ensure an alignment accuracy of less than or equal to 0.05 mm. At the same time, an optical alignment system is used, employing an industrial camera and image recognition software to automatically correct interlayer misalignment.

3. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, The welding method in step S2 is as follows: vacuum diffusion welding is used; the temperature for stainless steel is 1050-1150℃, and the temperature for titanium alloy is 850-950℃, the pressure is 5-15MPa, the holding time is 1-4 hours, and the vacuum degree is ≤1×10⁻³Pa.

4. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, The spinning forming method includes: using the spinneret to drive the fan-shaped filter blank to rotate, and applying radial pressure through rollers to gradually conform it to the molding mold to form a conical surface; The process parameters used are a rotation speed of 200-500 rpm, a feed speed of 0.5-2 mm / rad, and progressive forming in 3-5 passes. The roller pressure is 50-200 MPa, and the roller pressure increases with the increase of the cone angle.

5. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, The progressive rolling forming method includes: using a three-roll symmetrical rolling mill to progressively bend the filter screen along the generatrix of the conical surface, and controlling the taper by adjusting the roller spacing and tilt angle; the roller taper is 0-30 degrees, and the roller position is adjusted in real time by a CNC system; the initial roller spacing is 1.1 times the filter screen thickness, decreasing by 0.1-0.2 mm per pass, and the bending angle increases by 2-5 degrees per pass; the total number of passes = target cone angle / single increment.

6. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, Before spin forming or roll forming, the filter screen undergoes surface heat treatment, including: cleaning and surface treatment, furnace loading and fixing, solution treatment, aging strengthening, and passivation treatment. The cleaning and surface treatment are used to remove oil and oxides from the filter screen surface and to check for processing defects. The filter screen is fixed using a high-temperature resistant clamp during furnace loading. The solution treatment method is as follows: heat to 1040±10℃, hold for 1 hour, and then quickly cool with water or oil to form supersaturated martensite. The key point is to prevent the precipitation of σ phase during the cooling process. The aging strengthening method is as follows: heat to 480~620℃, hold for 4 hours, air cool to room temperature, precipitate copper-rich strengthening phase, and achieve a hardness of HRC40~45. The passivation treatment method is: immersion in nitric acid solution to enhance corrosion resistance.

7. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 1, characterized in that, The quality inspection in step S3 includes geometric accuracy inspection and pore integrity assessment. The geometric accuracy detection employs color laser confocal microscopy scanning measurement, combined with high-precision point cloud filtering and feature extraction algorithms.

8. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 7, characterized in that, The point cloud filtering algorithm employs a statistical filtering algorithm to remove outliers for each point. p i Calculate its neighborhood k Average distance of points d i : The global mean and standard deviation are: , Remove point, The threshold coefficient is used; after removing outliers, the remaining 3D point cloud data is processed based on the cone surface equation in the CAD model. The z-value is calculated from the x and y coordinates of the point cloud. This value is compared with the z-coordinate of the point cloud; the error is ≤0.1mm. It is the design half-cone angle of the conical surface; feature The extraction algorithm uses normal vector estimation to calculate the surface normal vector of the point cloud. p i Calculate its neighborhood covariance matrix C: ,in ; Perform eigenvalue decomposition on C: , For each eigenvalue, the eigenvector corresponding to the smallest eigenvalue is... That is, the normal vector; according to the normal vector Vector of the filter axis Obtain the calculated value of the half-cone angle. Filter axis vector The clamps of the confocal micrometer are collinear, and this vector is directly provided by the instrument; compare with the design value of the half-cone angle. and measured calculated values The error must be ≤0.1°.

9. The method for forming a cone-shaped filter suitable for aerospace equipment according to claim 7, characterized in that, The porosity integrity assessment uses a camera with backlight illumination and image processing algorithms to measure the pore diameter and pore spacing, allowing a maximum deformation of 5%. The image processing algorithm uses Gaussian filtering to smooth the image and suppress noise. The calculation formula is as follows: Gradient calculation: The Sobel operator is used to calculate the gradient magnitude G and direction. , , Non-maximum suppression preserves local maxima along the gradient direction, refines edges, and preserves weak edges if they are connected to strong edges.

10. A cone-shaped filter, characterized in that, It is manufactured using the cone filter molding method applicable to aerospace equipment as described in any one of claims 1 to 9.

Images