A method for fabricating a microwave absorbing honeycomb thin-walled structure

Abstract

This invention discloses a method for machining a microwave absorbing honeycomb thin-walled structure. The method involves adding process bosses to the thin-walled region of the structure to form the microwave absorbing honeycomb thin-walled process structure, machining the first and second surfaces of the structure, resulting in a microwave absorbing honeycomb thin-walled structure with guaranteed machining quality and accuracy. After semi-finishing, the invention re-holds the microwave absorbing honeycomb workpiece, and simultaneously changes the milling direction, selecting the thicker side for unidirectional reverse milling of the thin-walled region. This combination effectively solves the problem of milling damage caused by pulling up the thin-walled region during machining. Using an integral end mill for precision milling of the microwave absorbing honeycomb thin-walled structure effectively avoids phenomena such as cell crushing, hole wall tearing, and excessive burrs during machining. The machining error is ≤0.3mm, improving machining quality and accuracy.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing cell fabrication technology, and specifically to a method for fabricating a thin-walled microwave absorbing cell structure. Background Technology

[0002] With the development of modern electronic information technology and aviation technology, aircraft have placed higher demands on the shielding and absorption of electromagnetic waves, leading to the introduction of numerous new high-performance absorbing materials. Among these, absorbing honeycomb materials, due to their advantages such as light weight, high axial strength and stiffness, strong axial compressive strength, and good electromagnetic wave absorption performance, have been widely used in aircraft, particularly in edge structural components such as vertical tails, flaps, ailerons, bulges, and lips. Currently, absorbing honeycomb materials are mainly processed using high-speed CNC milling. However, absorbing honeycomb is a hexagonal porous structure with a cell wall thickness of only 0.06–0.1 mm. The side length of the cells is generally between 2 and 5 mm, resulting in high strength along the axial direction of the absorbing honeycomb, but very low strength in the plane perpendicular to the axial direction. These characteristics of absorbing honeycomb easily lead to surface quality problems during processing, such as milling marks, cell deformation, cell crushing, cell wall tearing, and numerous burrs. Meanwhile, because the in-plane force is non-directional, a small in-plane force can cause large deformation or even crushing. Traditional clamps and pressure plates cannot be used to hold and fix the honeycomb. Usually, adhesive bonding is used to hold the honeycomb, but the holding force is small and it is easy to lose the hold, resulting in low product yield and low processing efficiency.

[0003] In some aerospace-grade microwave absorbing honeycomb structures, there are special structures with thin-walled profiles, with a thickness of only 0.5–1.0 mm. During processing, these thin-walled microwave absorbing honeycomb structures are limited by the relatively small holding force of adhesive bonding, and because the thinness means that the vibration energy generated during milling cannot be completely absorbed by the honeycomb. This vibration is transmitted to the honeycomb surface bonded to the adhesive tape, causing the microwave absorbing honeycomb to separate from the tape. Subsequently, dust adheres to the bonding surface between the honeycomb and the tape, resulting in a decrease or even failure of the adhesive tape's holding force. This leads to the thin-walled microwave absorbing honeycomb structure becoming detached, milled, and exhibiting poor processing accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing thin-walled absorbing honeycomb structures, so as to solve the technical problems of easy milling damage and insufficient processing accuracy in the thin-walled areas during processing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The present invention provides a method for fabricating a microwave absorbing honeycomb thin-walled structure, comprising the following steps:

[0007] S1. Add process bosses to the thin-walled area of ​​the absorbing honeycomb thin-walled structure to form the absorbing honeycomb thin-walled process structure. The inner side of the process bosses forms a certain angle with the upper surface of the absorbing honeycomb thin-walled structure.

[0008] S2. Machining the first surface of the absorbing honeycomb thin-walled structure, specifically including: fixing the absorbing honeycomb blank on the flat pad and statically pressing the absorbing honeycomb blank; using a honeycomb end mill to perform layered circumferential cutting and climb milling to rough machine the absorbing honeycomb thin-walled process structure surface and process boss; using an integral end mill to finish machine the upper surface of the absorbing honeycomb thin-walled structure, the top surface of the process boss, the outer surface of the process boss, and the inner surface of the process boss.

[0009] S3. Processing the second surface of the microwave absorbing honeycomb thin-walled structure, specifically including:

[0010] After the first side of the absorbing honeycomb workpiece is processed, it is flipped over and fixed on the surface fixture. The absorbing honeycomb workpiece is statically pressed, and the thin-walled process structure surface of the absorbing honeycomb is rough machined by layer-by-layer circumferential cutting using a honeycomb end mill, leaving a machining allowance of 1 to 2 mm.

[0011] Use a honeycomb ball end mill to reciprocate cut the surface of the thin-walled wave-absorbing honeycomb structure, leaving a machining allowance of 0.5 to 1 mm;

[0012] Remove the absorbing honeycomb workpiece, clean it, and then fix the absorbing honeycomb workpiece on the surface fixture again. Static pressure is applied to the absorbing honeycomb workpiece, and an integral end mill is used to perform unidirectional reverse milling and finishing of the lower surface of the absorbing honeycomb thin-walled structure along the width direction from the side away from the outer side of the process boss towards the thin-walled area.

[0013] The process bosses are separated from the thin-walled area by using an integral end mill to vertically cut the thin-walled area of ​​the microwave absorbing honeycomb thin-walled structure.

[0014] The machining accuracy of the absorbing honeycomb thin-walled structure was measured using an in-machine measurement system; the absorbing honeycomb thin-walled structure was then removed and cleaned.

[0015] Furthermore, the angle between the inner side of the process boss in S1 and the upper surface of the absorbing honeycomb thin-walled structure is 95° to 100°.

[0016] Furthermore, the process boss is designed to increase the connection strength in thin-walled areas.

[0017] Furthermore, during the finishing of the upper surface of the absorbing honeycomb thin-walled structure in S2, the integral end mill has a tool swing angle of 1 to 5° with the upper surface of the absorbing honeycomb thin-walled structure, and the upper surface of the absorbing honeycomb thin-walled structure is finished by unidirectional milling along the width direction.

[0018] Furthermore, the S3 surface fixture is fixed on the machine tool worktable, and the installation accuracy of the surface fixture 7 is measured using the machine tool's on-machine measurement system.

[0019] Furthermore, the cutting parameters of the honeycomb ball end mill in S3 are set to n = 18000~24000 r / min. =2000~3000 mm / min, =1.0~1.5 mm, =10%~15% of the tool diameter.

[0020] Furthermore, in S3, the integral end mill has an angle of 1–5° with the lower profile of the microwave-absorbing honeycomb thin-walled structure, and the cutting parameters are set to n = 18000–20000 r / min. =1000~2000 mm / min, =0.5~1.0mm, =2~5 mm.

[0021] Furthermore, double-sided adhesive tape is used to hold the absorbing honeycomb blank during the holding process.

[0022] Furthermore, the static pressure is achieved by fully covering the absorber honeycomb blank with sandbags, and the static pressure time is 0.5 to 1 hour.

[0023] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects:

[0024] (1) After semi-finishing, the present invention fixes the absorbing honeycomb workpiece again and fixes it twice. At the same time, by changing the milling direction, the thin-walled area on the thicker side is selected to be reverse milled in one direction. The combination of the two effectively solves the problem that the thin-walled area of ​​the absorbing honeycomb thin-walled structure is easily pulled up and milled during processing.

[0025] (2) The present invention adopts an integral milling cutter to precision mill the surface of the thin-walled structure of the absorbing honeycomb. Compared with the honeycomb-specific combined milling cutter, this type of cutter is integral in structure, and its cutting disc and cutter bar are ground and formed as a whole. Unlike the honeycomb-specific combined milling cutter, which requires the cutting disc and cutter bar to be assembled together, it avoids assembly errors. When in use, it has smaller radial runout and end face runout, which can effectively avoid phenomena such as cell crushing, hole wall tearing, and many burrs during the processing of the absorbing honeycomb. The surface processing error is ≤0.3mm, which improves the processing quality and processing accuracy.

[0026] (3) This invention can be made using general composite five-axis CNC machining equipment, without the need to introduce expensive six-axis CNC ultrasonic machining equipment, which reduces the production cost for enterprises, and the process technology is relatively easy. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the microwave absorbing honeycomb thin-walled structure according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the absorbing honeycomb thin-walled process structure according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the first surface processing of the microwave absorbing honeycomb thin-walled structure according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the processing of the second surface of the microwave absorbing honeycomb thin-walled structure according to an embodiment of the present invention;

[0032] In the diagram: 1-Thin-walled area, 2-Process boss, 3-Absorbing honeycomb blank, 4-Double-sided tape, 5-Flat pad, 6-Integral end mill, 7-Surface fixture, 8-Absorbing honeycomb workpiece, 11-Inner side of process boss, 12-Upper surface of thin-walled structure of absorbing honeycomb, 13-Top surface of process boss, 14-Outer side of process boss, 15-Lower surface of thin-walled structure of absorbing honeycomb, 16-Side of thin-walled area. Detailed Implementation

[0033] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this application, 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, and 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, and therefore should not be construed as a limitation on this application; the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; furthermore, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0035] Example 1

[0036] like Figure 1-4 As shown, the present invention provides a method for fabricating a microwave absorbing honeycomb thin-walled structure, comprising the following steps:

[0037] S1. A process boss 2 is added to the thin-walled region 1 of the absorbing honeycomb thin-walled structure to form a absorbing honeycomb thin-walled process structure with process boss 2, wherein the inner side 11 of the process boss of the absorbing honeycomb thin-walled process structure forms an angle of 95° to 100° with the upper surface 12 of the absorbing honeycomb thin-walled structure.

[0038] S2. Machining of the first surface of the absorbing honeycomb thin-walled structure: The absorbing honeycomb blank 3 is fixed on the flat pad 5 with double-sided tape 4. Sandbags are used to fully cover the absorbing honeycomb blank 3 and apply static pressure for 0.5 to 1 hour. The absorbing honeycomb blank 3 is then rough-machined by layer-by-layer circumferential cutting and up-milling using a honeycomb end mill. The upper surface of the absorbing honeycomb thin-walled structure and the process boss 2 are then finished by using an integral end mill 6 with a tool swing angle of 1 to 5° with the upper surface 12 of the absorbing honeycomb thin-walled structure. The upper surface 12 of the absorbing honeycomb thin-walled structure is then finished by unidirectional milling along the width direction using an integral end mill 6. The top surface 13, the outer surface 14, and the inner surface 11 of the process boss are then finished by using an integral end mill 6.

[0039] S3, Second surface processing of microwave absorbing honeycomb thin-walled structure:

[0040] S31. Install and fix the profile fixture 7 on the machine tool worktable, and use the machine tool's on-machine measurement system to measure the installation accuracy of the profile fixture 7.

[0041] After the first side of the absorbing honeycomb workpiece 8 is turned over, double-sided tape 4 is used on the surface fixture 7, and sandbags are used to fully cover the absorbing honeycomb workpiece 8 for static pressure for 0.5 to 1 hour. Then, the surface of the absorbing honeycomb thin-walled process structure is rough machined by layer-by-layer ring cutting using a honeycomb end mill, leaving a machining allowance of 1 to 2 mm.

[0042] S32. Use a honeycomb ball end mill with chip-breaking function on the bottom cutting edge, and set the cutting parameters to n=18000~24000r / min. =2000~3000 mm / min, =1.0~1.5 mm, =10%~15% of the tool diameter, reciprocating cut the surface of the microwave absorption honeycomb thin-walled process structure, leaving a machining allowance of 0.5~1mm;

[0043] S33. Remove the absorbing honeycomb workpiece 8, clean it thoroughly, and then use double-sided tape 4 to fix the absorbing honeycomb workpiece 8 onto the mold surface fixture 7 again. Use sandbags to fully cover and statically press the absorbing honeycomb workpiece 8 for 0.5 to 1 hour. Use an integral milling cutter 6 with a tool swing angle of 1 to 5° with the lower mold surface 15 of the absorbing honeycomb thin-walled structure. Set the cutting parameters to n = 18000 to 20000 r / min. =1000~2000 mm / min, =0.5~1.0 mm, =2~5 mm, along the width direction, the lower surface 15 of the absorbing honeycomb thin-walled structure is precision machined by reverse milling from the thicker side to the thin-walled area in one direction;

[0044] S34. Use an integral end mill 6 to cut and separate the process boss 2 from the thin-walled area 16 of the vertical wave-absorbing honeycomb thin-walled structure.

[0045] S35. Use the machine tool's on-machine measurement system to measure the surface machining accuracy of the absorbing honeycomb thin-walled structure; remove the absorbing honeycomb thin-walled structure and clean it thoroughly.

[0046] The structures, functions, and connection forms disclosed herein can be implemented in other ways. For example, the embodiments described above are merely illustrative; multiple components may be combined or integrated into another component. Furthermore, the functional components in the various embodiments herein may be integrated into one functional component, or each functional component may exist physically separately, or two or more functional components may be integrated into one functional component.

[0047] 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 modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for processing a microwave absorbing honeycomb thin-walled structure, characterized in that, Includes the following steps: S1. Add process bosses (2) to the thin-walled area (1) of the absorbing honeycomb thin-walled structure to form the absorbing honeycomb thin-walled process structure, wherein the inner side (11) of the process bosses and the upper surface (12) of the absorbing honeycomb thin-walled structure form a certain angle; S2. Processing the first surface of the microwave absorbing honeycomb thin-walled structure, specifically including: The absorbing honeycomb blank (3) is fixed on the flat pad (5) and statically pressed. The surface of the thin-walled process structure and the process boss of the wave-absorbing honeycomb were rough machined by layered circumferential cutting and climb milling using a honeycomb end mill (2). The upper surface (12), the top surface (13), the outer surface (14), and the inner surface (11) of the process boss of the absorbing honeycomb thin-walled structure are precision machined using an integral end mill (6). S3. Processing the second surface of the microwave absorbing honeycomb thin-walled structure, specifically including: After the first surface is processed, the absorbing honeycomb workpiece (8) is flipped over and fixed on the surface fixture (7). The absorbing honeycomb workpiece (8) is statically pressed and the thin-walled process structure surface of the absorbing honeycomb is rough machined by layer-by-layer ring cutting using a honeycomb end mill, leaving a machining allowance of 1-2 mm. Use a honeycomb ball end mill to reciprocate cut the surface of the thin-walled wave-absorbing honeycomb structure, leaving a machining allowance of 0.5 to 1 mm; Remove the absorbing honeycomb workpiece (8), clean it, and fix the absorbing honeycomb workpiece (8) on the surface fixture (7) again. Static press the absorbing honeycomb workpiece (8), and use an integral milling cutter (6) to perform unidirectional reverse milling finishing on the lower surface (15) of the absorbing honeycomb thin-walled structure from the side away from the outer side (14) of the process boss to the thin-walled area (1) along the width direction. Using an integral end mill (6), the process boss (2) is cut and separated from the thin-walled area (1) on the side (16) of the thin-walled area of ​​the microwave absorbing honeycomb thin-walled structure; The machining accuracy of the absorbing honeycomb thin-walled structure was measured using an in-machine measurement system; the absorbing honeycomb thin-walled structure was then removed and cleaned. During the holding process, double-sided adhesive tape (4) is used to hold the absorbing honeycomb blank (3).

2. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, The angle between the inner side (11) of the process boss in S1 and the upper surface (12) of the absorbing honeycomb thin-walled structure is 95° to 100°.

3. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, When finishing the upper surface (12) of the absorbing honeycomb thin-walled structure in S2, the integral milling cutter (6) and the upper surface (12) of the absorbing honeycomb thin-walled structure have an angle of 1 to 5°. The upper surface (12) of the absorbing honeycomb thin-walled structure is finished by unidirectional milling along the width direction.

4. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, The S3 surface fixture (7) is installed and fixed on the machine tool workbench, and the installation accuracy of the surface fixture (7) is measured using the machine tool's on-machine measurement system.

5. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, The cutting parameters of the honeycomb ball end mill in S3 are set to n = 18000~24000 r / min. = 2000~3000mm / min, = 1.0~1.5mm, = 10%~15% of the tool diameter.

6. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, The integral end mill (6) in S3 has a tool swing angle of 1 to 5° with the lower profile (15) of the absorbing honeycomb thin-walled structure, and the cutting parameters are set to n = 18000 to 20000 r / min. = 1000~2000mm / min, = 0.5~1.0mm, = 2~5mm.

7. The method for processing a microwave absorbing honeycomb thin-walled structure according to claim 1, characterized in that, The static pressure is achieved by fully covering the sandbags with static pressure absorbing honeycomb blanks, and the static pressure time is 0.5 to 1 hour.

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