A forming tool design method of a large-thickness variable-curved-surface beam type wave-absorbing structural member

Abstract

The present application relates to a kind of large thickness, variable camber beam class wave-absorbing structure forming tool design method, comprising the following steps: A1, according to assembly relationship and profile variation, whole part is divided into multiple sectioned parts;A2, adjust the attitude of sectioned part and draw sectioned part blank according to the adjusted attitude of sectioned part;A3, corresponding sectioned part forming tool is designed according to each sectioned part blank respectively.The present application has the advantages that: by segmenting the part and then designing tool according to sectioned part, the designed tool is beneficial to reduce the manufacturing difficulty of part, and can also ensure the forming quality requirement of part.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing component processing technology, specifically to a method for designing forming tooling for a thick, variable-curvature beam-type microwave absorbing structure. Background Technology

[0002] To improve the stealth requirements of aircraft, it is necessary to reduce the radar cross section (RCS) of standard metal components in beam-type radar-absorbing structures. However, the original beam-type structures are usually made of polyester steel, which does not have radar-absorbing function and cannot meet the urgent need for improved stealth capabilities. Therefore, radar-absorbing structures made of radar-absorbing prepreg with extremely low fiber content can be used as a substitute.

[0003] According to the original specifications of beam-type structural members, a beam-type structural member is a section like... Figure 1 The variable-curvature arched part shown has a length × width × thickness of 2000mm × 42mm × 24mm. It features a large thickness, a high aspect ratio, and a complex curved surface. Furthermore, the molding material has an extremely low fiber content, significantly increasing the difficulty of the molding process. Therefore, a dedicated molding fixture needs to be designed specifically for the part's characteristics. The key issues to be addressed in the molding fixture design are: ① The part is long and has a complex curved surface, making it prone to deformation during integral manufacturing; ② The complex surface variations make prepreg layup and demolding difficult; ③ The part is thick, and the material used has a low fiber content, requiring the fixture design to consider thickness control and ensure the internal quality of the part (defect size (X+Y) / 2 ≤ 1). 5mm, where internal quality defects refer to delamination, debonding, inclusion, voids, etc., Y is the maximum lateral projection width of the defect; X is the projection length of the defect perpendicular to the Y direction; diffuse defects ≤ 10% of the inspection area, where diffuse defects refer to a group of scattered defects, and the inspection area refers to the surface area of ​​the inspected part); ④ When designing the tooling, it is necessary to consider that the upper and lower surfaces of the part blank are heated in a consistent manner to prevent the generation of large internal stress, so as to ensure that the deformation of the part (molding degree ≤ 0.2mm) meets the technical requirements, where molding degree refers to the gap between the actual molding surface of the part and the inspection fixture surface when the part is placed back on the inspection fixture (the inspection fixture surface is completely consistent with the theoretical molding surface of the part). Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for designing forming fixtures for thick, variable-curvature beam-type wave-absorbing structural components. By segmenting the parts and then designing fixtures based on the segmented parts, the designed fixtures can reduce the manufacturing difficulty of the parts and ensure the forming quality requirements of the parts.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for designing forming fixtures for thick, variable-curvature beam-type wave-absorbing structures includes the following steps:

[0007] A1. Divide the overall part into multiple segmented parts according to the assembly relationship and surface changes;

[0008] A2. Adjust the posture of the segmented parts and draw the blank of the segmented parts according to the adjusted posture.

[0009] A3. Design corresponding segmented part forming fixtures according to the blanks of each segmented part.

[0010] Further, in step A1, the overall part is divided into three segments along the length direction: left, middle, and right, according to the assembly relationship and surface changes. The length of the middle segment is 781 mm, and the lengths of the left and right segments are both 609.5 mm.

[0011] Further, in step A2, the orientation of the segmented part is adjusted with the lower surface of the segmented part as the film-coating surface until a viewing angle that facilitates layup is achieved; relative to the segmented part, the length of the segmented part blank is designed with a 30mm allowance on one side, the width of the segmented part blank is designed with a 5mm allowance on one side, and the thickness of the segmented part blank is designed with a 4mm allowance.

[0012] Furthermore, the design of tooling for segmented part forming includes the following steps:

[0013] B1. Design the base plate;

[0014] B2. Design cavities that match the shape of the segmented part blanks;

[0015] B3. Design a stop block assembly on the base plate to surround the forming cavity, and design a glue flow channel on the stop block assembly;

[0016] B4. Design the cover plate and design a cover plate boss on the bottom surface of the cover plate that matches the cavity;

[0017] B5. Design a drill template that connects to the stop block assembly in the allowance area at the end of the cavity.

[0018] Furthermore, the thermal expansion coefficients of the materials for the base plate, stop block, cover plate, cover plate boss, and drilling template are the same as or similar to those of the microwave absorbing prepreg.

[0019] Furthermore, in step B1, the base plate is designed to be machined as a whole, with a length allowance of 50mm on each side and a width allowance of 100mm on each side.

[0020] Furthermore, in step B2, the cavity height is set to h, the thickness of the segmented part blank is set to c, and the cavity is designed according to hc=10mm.

[0021] Further, in step B3, the stop assembly includes an inner stop and an outer stop located on the inner and outer sides of the cavity, respectively, and end stops located at both ends of the cavity. The bottom of the inner stop is provided with a connecting plate, which is connected to the bottom plate. The outer stop and the end stops are detachably mounted on the bottom plate. The inner stop, the outer stop, the end stops, and the connecting plate together form the cavity. The top surfaces of the inner stop, the outer stop, and the end stops are all designed with multiple glue flow grooves. The multiple glue flow grooves are arranged at equal intervals of 30mm along the length of the cavity. The two ends of the glue flow grooves are provided with openings. The width of the glue flow groove is designed to be 5mm, and the lower limit depth of the glue flow groove is designed to be 1mm.

[0022] Furthermore, in step B4, the area of ​​the top surface of the cover plate is S1, the area of ​​the bottom surface of the cover plate boss is S2, the cover plate is designed according to S1∶S2>3∶1, and the thickness of the cover plate is designed to be 20mm.

[0023] Furthermore, in step B5, screws are designed on the drill template to connect with the inner stop block, and pins are designed on the drill template located in the allowance area at the end of the cavity.

[0024] The present invention has the following advantages:

[0025] 1. By dividing the parts into segments and then designing corresponding segment forming fixtures for each segment, the manufacturing difficulty and deformation during part processing are reduced.

[0026] 2. Adjusting the orientation of segmented parts before designing the tooling for segmented parts facilitates lay-up and demolding operations during part processing, reducing manufacturing difficulty.

[0027] 3. When designing tooling for segmented parts, the base plate, stop block, cover plate, cover plate boss and drill template should be made of materials with the same or similar thermal expansion coefficient as the microwave absorbing prepreg, so that the mold fit of the segmented part blank after processing and demolding meets the requirement of ≤0.2mm.

[0028] 4. Through the design of the cover plate and the glue flow groove, the thickness of the produced part blank meets the machining requirements, and the internal quality of the part blank meets the requirements that the defect size (X+Y) / 2≤5mm and the diffuse defects ≤10% of the inspection area.

[0029] 5. The beam-type wave-absorbing structural component forming fixture designed by this invention can ensure the forming quality requirements of the parts, realize the manufacturing of such complex parts, and provide the possibility for the use of wave-absorbing materials in the manufacturing of more other parts of the product. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the beam-type wave-absorbing structure in this invention;

[0031] Figure 2 This is a schematic diagram of the segmented structure of the beam-type wave-absorbing structure in this invention;

[0032] Figure 3 This is a schematic diagram of the blanks of the segmented parts corresponding to each segmented part in this invention;

[0033] Figure 4 This is a schematic diagram of the overall structural design of the segmented part forming tooling in this invention, with the cover plate removed.

[0034] Figure 5 This is a schematic diagram of the structural design of the cover plate of the segmented part forming fixture in this invention.

[0035] In the diagram: 1. Base plate; 2. Cavity; 3. Stop block assembly; 4. Glue flow channel; 5. Cover plate; 6. Cover plate boss; 7. Drill template. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0037] like Figure 2-4 As shown, a method for designing forming fixtures for thick, variable-curvature beam-type wave-absorbing structures includes the following steps:

[0038] A1. Divide the overall part into multiple segmented parts according to the assembly relationship and surface changes;

[0039] A2. Adjust the posture of the segmented parts and draw the blank of the segmented parts according to the adjusted posture.

[0040] A3. Design corresponding segmented part forming fixtures according to the blanks of each segmented part.

[0041] Specifically, to address the issue of deformation in integrally molded products due to the curved surface and large aspect ratio of the parts, this technical solution preferably employs a method of manufacturing the product by molding the parts in segments and then assembling them, such as... Figure 2As shown, in step A1, the overall part is first divided into three segments—left, middle, and right—along its length direction according to the assembly relationship and surface changes. The left and right segments are symmetrical about the middle segment. To reduce the manufacturing difficulty of the product, in step A2, the posture of the segments is adjusted using the lower surface of the segments as the film-coating surface, so that the part is as horizontal as possible when viewed from above. This makes the prepreg layup operation more convenient when forming the segment blanks, thereby improving layup efficiency. Then, the blanks of each segment are drawn according to the posture of the segments. Finally, step A3 is performed. In this way, when using the segment forming fixture designed and manufactured by this technical solution to form each segment, the blanks of each segment are formed first, and then the blanks of each segment are precision-formed.

[0042] Since excessively long segmented parts can deform and become unassembleable, and it is impossible to adjust the segmented parts to a view that facilitates the layup for tooling design, it is preferable that, in step A1, according to the specifications of the beam-type wave-absorbing structure, the length of the middle segmented part is 781mm, and the lengths of the left and right segmented parts are both 609.5mm.

[0043] In addition, when drawing the blanks for segmented parts, a certain allowance needs to be left for the blanks to facilitate demolding and precision machining during product manufacturing. Preferably, such as... Figure 3 As shown, compared to segmented parts, the length of the segmented part blank has a 30mm allowance on one side, the width of the segmented part blank has a 5mm allowance on one side, and the thickness of the segmented part blank has a 4mm allowance. Allowing for a thickness allowance in the segmented part blank facilitates double-sided symmetrical machining during precision forming, thereby reducing the deformation of the segmented part.

[0044] Taking the design of a segmented part forming fixture as an example, after completing the preliminary work in steps A1 and A2 above, this technical solution includes the following steps when specifically designing the segmented part forming fixture:

[0045] B1. Design base plate 1;

[0046] B2. Design of cavities that match the shape of the segmented part blanks;

[0047] B3. Design a stop block assembly 3 on the base plate 1 to surround the cavity 2, and design a glue flow groove 4 on the stop block assembly 3;

[0048] B4. Design cover plate 5 and design cover plate boss 6 on the bottom surface of cover plate 5 to match cavity 2;

[0049] B5. Design a drill template 7 that connects to the stop block assembly 3 in the allowance area at the end of cavity 2.

[0050] Specifically, in step B1, preferably, the base plate 1 is designed to be machined as a single piece to ensure the overall airtightness of the tooling. The length of the base plate 1 is designed with a 50mm allowance on each side, and the width of the base plate 1 is designed with a 100mm allowance on each side. The allowances in the length and width of the base plate 1 are used to attach sealing strips when manufacturing segmented parts using segmented part forming tooling, thereby facilitating the sealing bag sealing operation when the segmented part blanks are cured.

[0051] In step B2, preferably, the height of cavity 2 is h, the thickness of the segmented part blank is c, and cavity 2 is designed according to hc=10mm.

[0052] In step B3, preferably, as follows: Figure 4 As shown, the stop assembly 3 includes an inner stop and an outer stop located on the inner and outer sides of the cavity 2, respectively, and end stops located at both ends of the cavity 2. The bottom of the inner stop is integrally formed with a connecting plate, which is welded to the base plate 1. The outer stop and the end stops are detachably connected to the base plate 1 by bolts or other connecting parts. The inner stop, outer stop, end stops and the connecting plate together form the cavity 2. The top surface of the inner stop, outer stop and end stops is provided with multiple glue flow grooves 4, and the two ends of the glue flow grooves 4 are provided with openings. More preferably, the multiple glue flow grooves 4 are arranged at equal intervals of 30mm along the length direction of the cavity 2. The width of the glue flow grooves 4 is designed to be 5mm and the lower limit depth of the glue flow grooves 4 is designed to be 1mm.

[0053] The baffle assembly 3 surrounds the molding cavity 2, which facilitates the shaping of the segmented part blank when using segmented part molding tooling to manufacture segmented parts in the future. The glue flow channel 4 is set to allow excess resin to flow out when the segmented part blank is encapsulated and cured. The outer baffle and the end baffle are detachable for demolding.

[0054] In step B4, preferably, as follows: Figure 5 As shown, the cover plate 5 and the cover plate boss 6 are integrally formed. Let the top surface area of ​​the cover plate 5 be S1, and the bottom surface area of ​​the cover plate boss 6 be S2. The cover plate 5 is designed according to S1∶S2>3∶1, and the thickness of the cover plate 5 is designed to be 20mm. When manufacturing segmented parts using segmented part forming tooling, the cover plate 5 covers the top of the stop block assembly 3. The cover plate boss 6 is embedded in the cavity 2, and when the segmented part blank is encapsulated and cured, it squeezes the microwave absorbing prepreg in the cavity until the cover plate 5 and the top surface of the stop block 3 are attached, so that the cover plate 5 is limited. At the same time, the cover plate 5 closes the top opening of the glue flow channel 4. Excess resin flows out from both ends of the glue flow channel 4 during the extrusion process. The contact surface between the segmented part blank and the connecting plate is the molding surface of the segmented part blank.

[0055] When manufacturing segmented parts using segmented part forming fixtures, the cavity height design facilitates the pressure application of the cover plate boss 6; the cover plate design ensures that the upper and lower surfaces of the segmented part blank are heated evenly, thus preventing large stress from causing part deformation during curing; the limiting design of the cover plate 5 facilitates the control of the thickness of the segmented part blank; the ratio design of S1 and S2 helps to increase the curing pressure, thereby ensuring the internal quality of the segmented part blank. Finally, with the cooperation between the cover plate 5, the cover plate boss 6 and the glue flow groove 4, the thickness of the obtained part blank can meet the machining requirements, and the internal quality of the part blank can meet the requirements that the defect size (X+Y) / 2≤5mm and the diffuse defects≤10% of the inspection area.

[0056] In step B5, preferably, as follows: Figure 4 As shown, screws are designed on the drill template 7 to connect with the inner stop block, and pins are designed on the drill template 7 located in the allowance area at the end of the cavity 2. The pins are set for machining positioning so that process positioning holes can be machined in the allowance area of ​​the segmented part blank corresponding to the pins. This facilitates the subsequent finishing of the segmented part blank by positioning the segmented part blank through the process positioning holes.

[0057] The design principles of the left and right segmented part forming fixtures are the same as those of the middle segmented part forming fixtures. Preferably, when designing each forming fixture, the base plate 1, the stop block assembly 3, the cover plate 5, the cover plate boss 6, and the drill template 7 are all made of materials with the same or similar thermal expansion coefficient as the microwave absorbing prepreg. This can further reduce the deformation of the segmented part blank after demolding when using the segmented part forming fixture to manufacture the segmented parts, thereby ensuring that the mold fit of the segmented part blank after processing and demolding meets the requirement of ≤0.2mm.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A forming tool design method for a large-thickness, variable-camber beam type wave-absorbing structural member, characterized by, The method comprises the following steps: A1, dividing the whole part into multiple segmented parts according to the assembly relationship and the profile change; A2, adjusting the posture of the segmented parts and drawing the segmented part blank according to the adjusted posture of the segmented parts; A3, designing the corresponding segmented part forming tool according to each segmented part blank; When designing the segmented part forming tool, the following steps are included: B1, designing the bottom plate (1); B2, designing the cavity (2) matched with the outer shape of the segmented part blank; B3, designing the stop block assembly (3) on the bottom plate (1) to enclose the cavity (2), and designing the glue flow groove (4) on the stop block assembly (3); B4, designing the cover plate (5) and designing the cover plate boss (6) matched with the cavity (2) on the bottom surface of the cover plate (5); B5, designing the drill jig plate (7) connected with the stop block assembly (3) in the remaining area of the end part of the cavity (2).

2. The forming tool design method of large-thickness, variable-camber beam type wave-absorbing structure according to claim 1, characterized in that: In step A1, the whole part is divided into left, middle and right three segmented parts along the length direction according to the assembly relationship and the profile change, wherein the length of the middle segmented part is 781mm, and the length of the left segmented part and the length of the right segmented part are both 609.5mm.

3. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 1, characterized in that: In step A2, the posture of the segmented part is adjusted with the lower surface of the segmented part as the mold surface until the visual angle for convenient layering is reached; relative to the segmented part, the length of the segmented part blank is designed with a 30mm excess on one side, the width of the segmented part blank is designed with a 5mm excess on one side, and the thickness of the segmented part blank is designed with a 4mm excess.

4. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 1, characterized in that: The materials of the bottom plate (1), the stop block assembly (3), the cover plate (5), the cover plate boss (6) and the drill jig plate (7) have the same or similar thermal expansion coefficient as that of the wave-absorbing pre-preg.

5. The forming tool design method of large thickness, variable-curved-beam wave-absorbing structure component according to claim 1, characterized in that: In step B1, the bottom plate (1) is designed to be integrally processed, and the length of the bottom plate (1) is designed with a 50mm excess on one side, and the width of the bottom plate (1) is designed with a 100mm excess on one side.

6. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 1, characterized in that: In step B2, the height of the cavity (2) is h, and the thickness of the segmented part blank is c, and the cavity (2) is designed according to h-c=10mm.

7. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 1, characterized in that: In step B3, the stop block assembly (3) includes an inner stop block and an outer stop block respectively located on the inner and outer sides of the cavity (2), and end stop blocks located at both ends of the cavity (2), the inner stop block is provided with a connecting plate fixedly connected with the bottom plate (1), the outer stop block and the end stop block are detachably arranged on the bottom plate (1), the inner stop block, the outer stop block, the end stop block and the connecting plate jointly enclose the cavity (2), the top surfaces of the inner stop block, the outer stop block and the end stop block are designed with a plurality of glue flow grooves (4), the plurality of glue flow grooves (4) are arranged at equal intervals along the length direction of the cavity (2) at an interval of 30mm, the two ends of the glue flow groove (4) are provided with openings, the width of the glue flow groove (4) is designed to be 5mm, and the lower limit depth of the glue flow groove (4) is designed to be 1mm.

8. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 1, characterized in that: In step B4, the top surface area of the cover plate (5) is S1, and the bottom surface area of the cover plate boss (6) is S2, the cover plate (5) is designed according to S1:S2>3:1, and the thickness of the cover plate (5) is designed to be 20mm.

9. The forming tool design method of large-thickness, variable-curved-beam wave-absorbing structure components according to claim 7, characterized in that: In step B5, the screw connected with the inner side stopper is designed on the drill template (7), and the pin is designed on the drill template (7) located in the residual area of the end of the cavity (2).

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