A special-shaped thin-walled porous ceramic antenna window fixing fixture and processing method

Abstract

The present invention discloses a fixing fixture and processing method for a special-shaped thin-walled porous ceramic antenna window, comprising: sealing the surface of the antenna window blank, fixing the antenna window on a machine tool platform by vacuum negative pressure; using a diamond tool to mill the inner and outer surfaces of the antenna window, first processing the curved surface of the antenna window, and then processing the surrounding areas of the antenna window: performing rough processing in multiple times, and reserving a certain margin for the next step of processing; using a diamond grinding head to perform fine grinding on the antenna window, and after completion, releasing the pressure to remove the antenna window to obtain the finished product. The present invention realizes vacuum adsorption fixing and clamping, solves the problems of deformation, low bonding efficiency and poor precision of traditional mechanical press-fitting, and effectively improves assembly processing efficiency. The present invention can be used as a module for intelligent processing, and can be automatically and unmanned through program control and automatic clamping, while solving the problems of accurate positioning and reference transfer, providing a basic module for intelligent manufacturing.

Description

Technical Field

[0001] The invention belongs to the field of mechanical processing of ceramic-based composite materials, and specifically relates to a fixing fixture for a special-shaped thin-walled porous ceramic antenna window and a processing method thereof. Background Art

[0002] Antenna windows, which provide wave transmission, load-bearing, and thermal insulation, are integrated structural and functional products. With the development of missile aerodynamic shapes and functions, antenna windows installed on missile bodies are increasingly characterized by thin-walled, irregular shapes, requiring higher machining precision. With the market-driven selection of optimal models, the requirements for antenna window machining precision, efficiency, and cost are also increasing.

[0003] Because missiles operate at high Mach numbers, high body temperatures, and high scouring forces, antenna windows are often made of quartz ceramic composites and nitride ceramic composites to meet the requirements of high-temperature resistance, high strength, and wave-transmitting performance. Mechanical clamping or adhesive fixation is generally used during the processing of special-shaped thin-walled porous ceramic antenna windows. However, since ceramics are brittle and high-hardness materials, and the antenna has a thin-walled structure, stress is present during clamping, resulting in easy deformation, low precision, and low efficiency. The datum conversion after deformation is also inaccurate, which is a difficulty in antenna window processing. Furthermore, with the development of intelligent processing, traditional processing methods and fixtures are no longer well-suited to intelligent processing technology. Summary of the Invention

[0004] In response to the problems described in the background technology, the purpose of the present invention is to provide a special-shaped thin-walled porous ceramic antenna window fixing fixture and processing method suitable for intelligent processing, so as to improve the clamping and alignment efficiency of replacement parts, significantly shorten the processing cycle, improve processing efficiency, improve processing accuracy, and reduce processing costs.

[0005] To achieve the above-mentioned object, the present invention provides a method for processing a special-shaped thin-walled porous ceramic antenna window, comprising the following steps:

[0006] S1, sealing the surface of the antenna window blank: the surface of the antenna window is polished and smoothed, and a layer of hot melt adhesive film is applied to the inner and outer surfaces to seal the antenna window;

[0007] S2, according to the antenna window surface structure, select a suitable fixing fixture and fix the antenna window on the machine tool platform through vacuum negative pressure;

[0008] S3: Use diamond cutting tools to mill the inner and outer surfaces of the antenna window. First, machine the curved surface of the antenna window. Then, perform rough machining around the antenna window in multiple steps. Each cutting depth should not exceed 0.5 mm, and a margin of no more than 0.5 mm should be reserved for the next step of machining.

[0009] S4, use a diamond grinding head to fine-grind the antenna window. After completion, release the pressure and remove the antenna window to complete the product.

[0010] Preferably, in S1, the antenna window material is pure ceramic, fiber-reinforced composite ceramic, or porous multiphase ceramic.

[0011] Preferably, in S1, the inner and outer surfaces of the antenna window are polished with corundum sandpaper to be smooth and free of convex, concave and sharp points, and then coated with hot melt adhesive film.

[0012] Further preferably, the thickness of the hot melt adhesive film covering the inner and outer surfaces of the antenna window is 50 to 100 microns.

[0013] More preferably, the hot melt adhesive film is spread on the inner and outer surfaces of the antenna window respectively, placed in a forced air drying oven, heated to 20°C to 30°C above the melting point of the hot melt adhesive, kept warm for 30min to 60min, and then cooled with the oven.

[0014] Preferably, in S2, the antenna window is fixed by evacuating the vacuum to a vacuum degree of ≤-0.08 MPa.

[0015] Preferably, in S3, the arc surface is machined using a diamond milling cutter with a tool radius greater than R2; and the surrounding surface is machined using a diamond milling cutter with a tool radius less than R0.4.

[0016] Preferably, in S3, the spindle speed for milling is above 4000 r / min, and the spindle speed for grinding is above 8000 r / min.

[0017] To achieve the above-mentioned objectives, the present invention provides a fixing fixture for a special-shaped thin-walled porous ceramic antenna window, comprising: a profile seat and a bottom cover; the profile seat and the bottom cover are sealed and a cavity is provided between them; the profile seat is provided with a molding surface adapted to the product profile; the molding surface is provided with a plurality of through holes connected to the cavity at intervals, each of the through holes is provided with a vacuum adsorption nozzle for adsorbing the workpiece, and the top of the vacuum adsorption nozzle extends out of the molding surface; at least one vacuum quick connector is provided on the bottom cover; one end of the vacuum quick connector is connected to a vacuum source, and the other end is connected to the cavity.

[0018] Preferably, the vacuum adsorption nozzle comprises a joint sealed with the through hole, and a bellows sleeved at the outlet of the joint; one end of the bellows is sealed with the joint, and the other end is provided with a adsorption nozzle.

[0019] Further preferably, the bellows is connected to the joint via a clamp.

[0020] Further preferably, a spiral spring coil is embedded in the bellows, thereby providing elastic pressure for the bellows to seal against the antenna window and providing support force to prevent the bellows from being deflated by vacuum.

[0021] Further preferably, the bellows has a diameter of 10 to 40 mm and a wall thickness of 1 to 5 mm.

[0022] Preferably, two adjacent sides of the top surface of the profile seat are provided with positioning bosses, and the positioning bosses align and position the workpiece by positioning the two adjacent sides of the workpiece.

[0023] Further preferably, the height of the positioning boss is smaller than the thickness of the workpiece.

[0024] Preferably, the profile seat includes a convex profile seat and / or a concave profile seat; the convex profile seat is provided with a convex arc profile surface adapted to the product cavity; the concave profile seat is provided with a concave arc profile surface adapted to the product convex part.

[0025] The beneficial effects of the present invention are as follows: by sealing the breathable porous material and designing an elastic vacuum nozzle, the present invention achieves vacuum adsorption fixation and clamping, solving the problems of deformation, low bonding efficiency, and poor precision caused by traditional mechanical press-fitting, and effectively improving assembly and processing efficiency. The present invention can serve as a module for intelligent processing, enabling automated, unmanned clamping and clamping through program control, while also solving the problems of accurate positioning and reference transfer, providing a foundational module for intelligent manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic top view of the convex fixing fixture of the present invention;

[0027] Figure 2 yes Figure 1 AA cross-section of

[0028] Figure 3 It is a schematic diagram of the assembly of the convex fixing fixture of the present invention;

[0029] Figure 4 yes Figure 3 BB cross-section diagram;

[0030] Figure 5 is a top view schematic diagram of the concave fixing fixture of the present invention;

[0031] Figure 6 yes Figure 5 CC cross-section diagram;

[0032] Figure 7 It is a schematic diagram of the assembly of the concave fixing fixture of the present invention;

[0033] Figure 8 yes Figure 7 DD cross-section diagram;

[0034] Figure 9 It is a structural schematic diagram of the vacuum adsorption nozzle of the present invention. DETAILED DESCRIPTION

[0035] The following further describes the technical solutions (including preferred technical solutions) of the present invention in detail by way of accompanying drawings and enumerating some optional embodiments of the present invention. It should be understood that the described embodiments are merely some, and not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0036] like Figures 1 to 9 As shown, the special-shaped thin-walled porous ceramic antenna window fixing fixture and processing method designed by the present invention

[0037] S1: Design a fixing fixture based on the special-shaped thin-walled porous ceramic antenna window to be processed. The fixing fixture is equipped with 12 vacuum adsorption nozzles to fix the antenna window through vacuum negative pressure;

[0038] A fixing fixture is designed based on the antenna window profile. It includes a convex fixture and a concave fixture. The convex and concave fixtures are generally identical in structure, differing primarily in their design surfaces. Both fixtures include a profile seat 1, a bottom cover 2, a vacuum nozzle 3, bolts 4, a sealing ring 6, and a vacuum quick connector 5. The profile seat 1 and bottom cover 2 are sealed together, with a cavity 7 defined between them. The profile seat 1 is provided with a design surface that matches the antenna window profile. Multiple through-holes are spaced apart on the design surface, connecting to the cavity 7. Each through-hole houses a vacuum nozzle 3 for attaching the antenna window 9, with the top of the vacuum nozzle 3 extending beyond the design surface. The bottom cover 2 is provided with at least one vacuum quick connector 5. One end of each vacuum quick connector 5 is connected to a vacuum source, and the other end is connected to the cavity 7.

[0039] The profile seat 1 and bottom cover 2 are secured by four bolts 4. Twelve vacuum nozzles 3 are designed. The sealing ring 6 is a flexible silicone rubber ring with a Shore hardness of 80±5 and a white color, sealing the fixture cavity 7. A vacuum quick connector 5 can be designed on the bottom of the bottom cover 2 as needed, allowing for quick and automatic connection to an external vacuum source. Positioning bosses 8 are located on two adjacent sides of the top surface of the profile seat 1. These bosses 8 align the antenna window 9 by aligning it with its adjacent edges. These two bosses 8 form a clamping and alignment reference, allowing for quick clamping and alignment of the antenna window 9.

[0040] The upper molding surface of the molding seat 1 is consistent with the product's molding surface, and the vacuum suction nozzle 3 is 5mm higher than the molding surface. The molding seat 1 includes a convex molding seat and a concave molding seat. The convex molding seat has a convex molding surface 1.1 that adapts to the product's concave cavity; the concave molding seat has a concave molding surface 1.2 that adapts to the product's convex part.

[0041] The vacuum nozzle 3 comprises a bellows 3.1, a spring ring 3.2, a connector 3.3, and a clamp 3.4. The connector 3.3 is threadedly connected to the through-hole and sealed. One end of the bellows 3.1 is sealed to the connector 3.3, and the other end is provided with a suction nozzle 3.5. The bellows 3.1 is made of flexible silicone rubber, ensuring a tight seal against the antenna window. A helical spring ring 3.2 is embedded within the bellows 3.1, providing elastic pressure for the seal between the bellows 3.1 and the antenna window, while also providing support to prevent collapse during vacuum.

[0042] The bellows has a diameter of 10 to 40 mm and a wall thickness of 1 to 5 mm. In this embodiment, the bellows 3.1 has a diameter of 20 mm and a wall thickness of 2 mm.

[0043] The connection surface between connector 3.3 and bellows 3.1 is coated with silicone sealant and fixed with clamp 3.4 to ensure strength and sealing. Where vacuum nozzle 3 contacts antenna window 9, the opening of bellows 15 should be parallel to the antenna window contact surface.

[0044] S2: Use 120-grit corundum sandpaper to polish the antenna window surface to make it smooth. Cover the inner and outer surfaces with a layer of hot-melt adhesive film to seal the antenna window.

[0045] Ceramic antenna windows can be made of pure ceramic, fiber-reinforced composite ceramic, or porous composite ceramic. The inner and outer surfaces of the ceramic antenna window should be polished smooth with corundum sandpaper, ensuring no bumps or sharp points. The inner and outer surfaces of the antenna window are covered with a hot-melt adhesive film with a thickness of 50 to 100 microns. The hot-melt adhesive film is applied to the inner and outer surfaces of the antenna window, placed in a forced-air drying oven, heated to 20 to 30°C above the melting point of the hot-melt adhesive, held at this temperature for 30 to 60 minutes, and then allowed to cool in the oven. Ceramic antenna windows are porous and breathable, and cannot be directly fixed with vacuum suction. The hot-melt adhesive film acts as a sealant, adhering only to the surface of the antenna window and not penetrating into the ceramic material, thereby preventing product contamination. Sealing methods such as resin coatings can penetrate into the ceramic material and contaminate the product.

[0046] In this embodiment, the ceramic antenna window is made of a quartz fiber-reinforced quartz composite ceramic material. The blank is pre-pressed in a mold and then formed into a relatively regular surface. The blank is 5.5 mm thick, and the finished dimensions are 2.5 mm thick, 150 mm long, and 80 mm wide. The ceramic porosity is 35%. The inner and outer surfaces of the ceramic antenna window are polished smooth with 80-grit corundum sandpaper until there are no bumps or sharp points. Surface particles are then removed using a vacuum cleaner. The inner and outer surfaces of the antenna window are coated with a 60-micron thick hot-melt adhesive film. The hot-melt adhesive film is applied to the inner and outer surfaces of the antenna window, pressed and adhered, and then placed in a forced air drying oven, heated to 110°C (melting point of hot-melt adhesive: 85°C), held at this temperature for 40 minutes, and then cooled. The quartz fiber reinforced quartz composite ceramic antenna window is a porous material with air permeability. It cannot be directly fixed by vacuum adsorption. The hot-melt adhesive film serves as a seal. The hot-melt adhesive film only adheres to the surface of the antenna window and will not penetrate into the interior of the ceramic material and contaminate the product. Sealing methods such as resin coating will penetrate into the interior of the ceramic material and contaminate the product.

[0047] S3: Fix the concave surface fixture to the machine platform, connect it to the external vacuum line through the vacuum quick connector, place the antenna window concave side up on the concave surface fixture, and evacuate to a vacuum degree of -0.085 MPa;

[0048] The vacuum nozzle is pressed flush with the fixture surface by the product's own weight or external pressure, simultaneously sealing the nozzle against the antenna window. Evacuate to a vacuum of ≤ -0.08MPa to secure the product. Concave surfaces are machined first, allowing alignment with the fixture using the product's own weight or external pressure. The order of machining convex and concave surfaces can be adjusted based on the structural characteristics of different product sizes.

[0049] S4: Process the concave surface of the antenna window using a diamond tool in two or more feeds, with the last feed amount not exceeding 0.2 mm. Release the pressure and remove the antenna window.

[0050] A diamond tool is used to mill the concave surface of the antenna window. The concave arc surface is milled first. A diamond milling cutter with a tool radius greater than R2 is used for the arc surface. Then the perimeter of the window is milled. A diamond milling cutter with a tool radius less than R0.4 is used for the perimeter. The antenna window is first rough-machined with a diamond milling cutter in two or more passes, with each layer cutting no more than 0.5mm. The final pass leaves a 0.2mm margin and a diamond grinding head is used to fine-grind the concave arc surface of the antenna window to improve processing accuracy and surface quality. The spindle speed for milling is above 4000r / min, and the spindle speed for grinding is above 8000r / min. A milling cutter is used to mill the six mounting holes of the antenna window. The antenna window is fitted on a fixed fixture, and the ceramic surface is not prone to chipping and has good integrity.

[0051] S5: The convex surface fixing fixture is fixed to the machine tool platform. The vacuum is connected through the vacuum quick connector. The antenna window is placed on the convex surface fixing fixture with the convex surface facing upwards. The product is fixed by vacuum suction.

[0052] The machined concave surface is fitted to the fixture and aligned using the positioning datum. The processed product then provides the foundation for product flipping via mechanical gripping or vacuum clamping. The positioning datum on the fixture is automatically and quickly aligned, enabling transfer of the positioning datum.

[0053] S6: When processing the convex surface of the antenna window, positioning and alignment are performed using the positioning boss 8 as a positioning reference. The height of the positioning boss 8 is 1.5 mm, which is lower than the upper surface of the antenna window being processed. After the processing is completed, the pressure is released and the antenna window is removed, and the processing is completed.

[0054] When machining the convex surface, the fixture is first used to align the datum with the two surfaces of the antenna window, which can achieve quick clamping and alignment. A Φ2 milling cutter is used to mill a small hole first, then expand the hole to machine the Φ4 mounting hole of the antenna window.

[0055] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for processing a special-shaped thin-walled porous ceramic antenna window, characterized in that: The following steps are involved: S1, sealing the surface of the antenna window blank: the surface of the antenna window is polished and smoothed, and a layer of hot melt adhesive film is applied to the inner and outer surfaces to seal the antenna window; S2. According to the surface structure of the antenna window, a suitable fixing fixture is selected to fix the antenna window on the machine tool platform by vacuum negative pressure; the fixing fixture includes: a surface seat and a bottom cover; the surface seat and the bottom cover are sealed and a cavity is provided between them; the surface seat is provided with a molding surface adapted to the product surface; a plurality of through holes connected to the cavity are provided at intervals on the molding surface, each of the through holes is provided with a vacuum suction nozzle for adsorbing the workpiece, and the top of the vacuum suction nozzle extends out of the molding surface; at least one vacuum quick connector is provided on the bottom cover; one end of the vacuum quick connector is connected to the vacuum source, and the other end is connected to the cavity; wherein, the vacuum suction nozzle includes a connector sealed to the through hole, and a bellows sleeved at the outlet of the connector; one end of the bellows is sealed to the connector, and the other end is provided with a suction nozzle; a spiral spring coil is embedded in the bellows; S3: Use diamond cutting tools to mill the inner and outer surfaces of the antenna window. First, machine the curved surface of the antenna window. Then, perform rough machining around the antenna window in multiple steps. Each cutting depth should not exceed 0.5 mm, and a margin of no more than 0.5 mm should be reserved for the next step of machining. S4, use a diamond grinding head to fine-grind the antenna window. After completion, release the pressure and remove the antenna window to complete the product.

2. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: In S1, the inner and outer surfaces of the antenna window are polished with corundum sandpaper to be smooth and without bumps, concave or sharp points, and then covered with hot-melt adhesive film; the thickness of the hot-melt adhesive film covering the inner and outer surfaces of the antenna window is 50 to 100 microns.

3. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 2, characterized in that: The hot melt adhesive film is spread on the inner and outer surfaces of the antenna window respectively, placed in a forced air drying oven, heated to 20°C to 30°C above the melting point of the hot melt adhesive, kept warm for 30min to 60min, and then cooled with the oven.

4. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: In S2, the antenna window is fixed by evacuating the vacuum to a vacuum degree of ≤-0.08 MPa.

5. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: In S3, the arc surface is processed by a diamond milling cutter with a tool radius greater than R2; the surrounding surface is processed by a diamond milling cutter with a tool radius less than R0.4; in S3, the spindle speed for milling is above 4000r / min, and the spindle speed for grinding is above 8000r / min.

6. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: The bellows has a diameter of 10 to 40 mm and a wall thickness of 1 to 5 mm.

7. The method for processing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: Two adjacent sides of the top surface of the profile seat are provided with positioning bosses, and the positioning bosses align and position the workpiece by positioning the two adjacent sides of the workpiece; the height of the positioning bosses is less than the thickness of the workpiece.

8. The method for fixing a special-shaped thin-walled porous ceramic antenna window according to claim 1, characterized in that: The profile seat includes a convex profile seat and / or a concave profile seat; the convex profile seat is provided with a convex arc profile surface adapted to the product cavity; the concave profile seat is provided with a concave arc profile surface adapted to the product convex part.

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