Manufacturing Method of Cylindrical Rubber-Cored Flexible Die-Assisted Variable Cross-Section Composite Floor Beam

Abstract

Manufacturing method of a cylindrical rubber sandwich soft mold assisted variable cross-section composite floor beam, belonging to the field of composite material forming technology. The method comprises the following steps: S1. fabricating an integral cylindrical rubber sandwich soft mold; S2. customizing a hollow metal core mold; S3. preparing an I-shaped floor beam preform; S4. combining the lower flange with the I-shaped floor beam preform; S5. placing the cylindrical rubber sandwich soft mold and the hollow metal core mold in the notch of a preformed C-shaped beam; S6. completing the mold combination of the upper cover mold and the lower cover mold; S7. evacuating the tubular vacuum bag and curing the entire device; S8. demolding to obtain a variable cross-section I-shaped floor beam. The cylindrical rubber sandwich soft mold of the present invention is applicable to the manufacturing of variable cross-section I-shaped floor beams with various sizes and profiles, and can improve the manufacturing efficiency and material utilization rate, and reduce the unit manufacturing cost. The present invention can ensure uniform pressure in all directions during the curing of the variable cross-section I-shaped floor beam, and in particular, can ensure the quality of parts at the variable cross-section.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming, and particularly relates to a manufacturing method for a variable cross-section composite floor beam assisted by a cylindrical rubber sandwich soft mold. Background Art

[0002] In civil aircraft, the number of fuselage floor beams is large and the structures are similar. Metal floor beams have disadvantages such as high weight, high energy consumption, easy corrosion, and poor fatigue resistance. Composite materials have excellent properties such as high specific strength and specific modulus, strong designability, easy integral forming, corrosion resistance, and light weight. Using composite materials to prepare floor beams has become the preferred choice for a new generation of civil aircraft.

[0003] Currently, the commonly used composite floor beam is of the "I" type, with high requirements for the appearance and forming quality. Currently, metal molds are commonly used during curing, but they have poor matching with the sheets in the characteristic area and uneven curing pressure transmission, resulting in quality defects such as out-of-tolerance thickness, internal delamination, and out-of-tolerance porosity in the parts. In addition, the metal mold is not open with the part, which easily leads to poor temperature uniformity of the part during curing and difficult demolding. Forced measures (such as prying, pulling, and extracting) need to be used for demolding, which not only causes the mold to deform but also easily makes the part have delamination defects, reducing the service life of the mold and the qualified rate of the part. Another forming method is to use a casting process to prepare an integral square silicone rubber to replace the metal core mold, and use the thermal expansion of the silicone rubber core mold to apply pressure, so that the I-beam is simultaneously compressed in all directions during the vulcanization molding process; however, in this scheme, the silicone rubber core mold is not open, and there is still a problem of poor temperature uniformity during the curing process of the part. Relying on the expansion of the silicone rubber to apply pressure easily results in insufficient pressure application to the part, and there are problems such as a large amount of silicone rubber used, low manufacturing efficiency, and low material utilization rate. Summary of the Invention

[0004] The purpose of the present invention is to provide a manufacturing method for a variable cross-section composite floor beam assisted by a cylindrical rubber sandwich soft mold, which can ensure the consistency of pressure transmission during the curing process, is easy to demold, and the sandwich layer enables the rubber soft mold to have a certain stiffness, which can ensure the part profile to a certain extent.

[0005] The technical solution adopted by the present invention is: a manufacturing method for a variable cross-section composite floor beam assisted by a cylindrical rubber sandwich soft mold, including the following steps:

[0006] S1. Fabricate an integral cylindrical rubber sandwich soft mold, and control the inner profile of the variable cross-section I-shaped floor beam through the outer profile of the cylindrical rubber sandwich soft mold;

[0007] S2. Customize a hollow metal core mold, which can provide a supporting force during the curing of the preformed C-shaped beam;

[0008] S3. Prepare a preform of the I-shaped floor beam;

[0009] S4. The lower edge strip and the I-type floor beam preformed body combination;

[0010] S5. The cylindrical rubber sandwich soft mold and the hollow metal core mold are placed in the notch of the preformed C-beam;

[0011] S6. Complete the mold combination of the upper cover mold and the lower cover mold;

[0012] S7. Evacuating and curing the entire apparatus of the tubular vacuum bag in the cylindrical rubber sandwich soft mold cavity;

[0013] S8. Demoulding to obtain variable-section I-shaped floor beams.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The cylindrical rubber sandwich soft mold of the present invention is suitable for the manufacture of variable-section I-shaped floor beams of various sizes and shapes. The profile and layup design can be carried out according to the required size and stiffness of variable-section I-shaped floor beams of different thicknesses and shapes (the stiffness of the soft mold can be adjusted by changing the sandwich layer structure). The sandwich layer structure can be customized to ensure the part profile, and multiple closed cavities can be formed by solidification at one time to form multiple "I-shaped" beams, thereby improving manufacturing efficiency and material utilization and reducing the manufacturing cost of each piece.

[0016] 2. The present invention adopts an integral cylindrical rubber sandwich soft mold, which can ensure that the pressure in all directions is uniform during the curing of the variable-section I-type floor beam, especially the quality of the parts at the variable section; the sandwich layer laying is eliminated at the rounded corners, which can ensure the internal quality of the rounded corner area of the parts; the soft mold stiffness is adjusted by designing the number of carbon fiber sandwich layers to ensure the part surface; the cylindrical rubber sandwich soft mold is formed separately by a mold, and the surface flatness is good, which can ensure the surface quality of the parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the cylindrical rubber sandwich soft mold of the present invention;

[0018] Figure 2 This is a schematic diagram of the molding process of the cylindrical rubber sandwich soft mold of the present invention;

[0019] Figure 3 Schematic diagram of the hollow metal core mold of the present invention;

[0020] Figure 4 This is a schematic diagram of the paving of flat sheet materials of the present invention;

[0021] Figure 5 is a schematic diagram of the preformed C-beam of the present invention;

[0022] Figure 6 This is a schematic diagram of the combination of the hollow metal core mold and the cylindrical rubber sandwich soft mold of the present invention;

[0023] Figure 7 Yes Figure 6 Partial enlarged view of part A;

[0024] Figure 8 Schematic diagram of the mold assembly and forming of the present invention;

[0025] Among them: 1. Upper cover plate mold; 2. Lower cover plate mold; 3. Side support column; 4. Soft mold web positioning pin; 5. Soft mold positioning plate; 6. Cylindrical rubber sandwich soft mold; 7. Carbon fiber sandwich layer; 8. Soft mold forming female mold; 9. Unvulcanized rubber layer; 10. Flat laying mold; 11. Flat sheet; 12. C-beam preforming mold; 13. Preformed C-beam; 14. Upper flange; 15. Lower flange; 16. Twisting strip; 17. Hollow metal core mold; 18. Metal core mold web positioning plate. Specific implementation method

[0026] In order to better understand the purpose, structure and function of the present invention, the following further detailed description of the present invention will be made in conjunction with the attached drawings.

[0027] Refer to Figures 1 to 8 , a manufacturing method of a cylindrical rubber sandwich soft mold assisted variable cross-section composite floor beam of the present invention includes the following steps:

[0028] S1. Manufacture the overall cylindrical rubber sandwich soft mold 6, and control the inner surface of the variable cross-section I-shaped floor beam through the outer surface of the cylindrical rubber sandwich soft mold 6;

[0029] The first scheme for manufacturing the overall cylindrical rubber sandwich soft mold 6: Use a rubber soft mold forming mold, which consists of a combined female mold and a male mold, and inject and mold the cylindrical rubber sandwich soft mold 6.

[0030] The second scheme: The specific steps are as follows:

[0031] S11. Manually lay and stack the unvulcanized rubber layer 9 with a thickness of 1.5 mm in the soft mold forming female mold 8, and perform vacuum compaction;

[0032] S12. On the unvulcanized rubber layer 9, continue to lay and stack the carbon fiber sandwich layer 7. A total of 4 layers of the carbon fiber sandwich layer 7 are laid and stacked, and vacuum compaction is performed; Adjust the soft mold stiffness by designing the number of layers of the carbon fiber sandwich layer to ensure the part surface;

[0033] S13. On the unvulcanized rubber layer 9 and the carbon fiber sandwich layer 7, continue to lay and stack another layer of unvulcanized rubber layer 9, and use a vacuum bag for compaction;

[0034] S14. According to steps S11 to S13, stack another set of sandwich rubber soft molds;

[0035] S15. Flip the two sets of laminated sandwich rubber soft molds and the forming mold, close the mold, encapsulate, put it into the autoclave for curing, and demold to obtain the integral cylindrical rubber sandwich soft mold 6. The curing parameters are as follows: pressurize at a rate of 0 - 0.5 MPa / min to 4 - 8 MPa, then start heating at a rate of 1 - 3 °C / min to 180 - 200 °C, and cure at a constant temperature for 9 - 12 h, then cool down to 40 - 60 °C at a rate of 0 - 3 °C / min, and demold out of the autoclave to obtain the cylindrical rubber sandwich soft mold 6.

[0036] In the above steps, the vacuum degree for vacuum compaction is -0.07 MPa, and the compaction time is 6 min;

[0037] The carbon fiber sandwich layer 7 is in a form that is continuous in length and segmented in configuration; cancel the laying of the carbon fiber sandwich layer 7 at the rounded corners of the cylindrical rubber sandwich soft mold 6, which can ensure the internal quality of the rounded corner area of the part;

[0038] The cylindrical rubber sandwich soft mold 6 is the same length as the flat sheet 11;

[0039] Schematic diagram of the forming process of the cylindrical rubber sandwich soft mold 6, as Figure 2 shown.

[0040] Place a layer of non - porous isolation film on the outer side of the cylindrical rubber sandwich soft mold 6, and put a tubular vacuum bag into the cavity of the cylindrical rubber sandwich soft mold 6. The tubular vacuum bag is 3 mm longer than the soft mold.

[0041] The cylindrical rubber sandwich soft molds 6 are used in combination to form multiple closed cavities, which can realize the single - time forming of multiple I - shaped floor beams.

[0042] The mold in Scheme 2 uses a combined C - type female mold, which can be the same mold as the female mold in Scheme 1.

[0043] S2. Customize a hollow metal core mold 17 with a thickness of 5 mm - 12 mm according to the variable cross - section characteristics of the I - shaped floor beam, which can provide support during the curing of the pre - formed C - beam 13. For easy demolding, the hollow metal core mold 17 adopts a combined structure; the hollow metal core mold 17 is preferably made of aluminum or invar steel. As Figure 3 shown,

[0044] S3. Prepare the pre - formed body of the I - shaped floor beam;

[0045] S31. Adopt the automatic tape laying process to complete the laying of the flat sheet 11 on the flat laying mold 10;

[0046] Automatic tape laying process: Use an automatic tape laying machine to lay the flat sheet 11 on the laying platform (flat laying mold 10), or adopt the manual laying process to lay the beam flat sheet 11 on the flat tooling (flat laying mold 10). As Figure 4As shown

[0047] S32. Transform the flat sheet 11 into a preformed C-shaped beam 13, and manufacture two preformed C-shaped beams 13 on the left and right; as Figure 5 shown

[0048] Use a thermal diaphragm machine to thermally diaphragm the flat sheet 11 made in S31 on the C-shaped beam preforming die 12 through the thermal diaphragm process to obtain the preformed C-shaped beam 13, or directly manually lay it on the preforming die to form the preformed C-shaped beam 13;

[0049] S32. Combine the two preformed C-shaped beams 13 on the left and right, place the wick strip 16 at the upper and lower notches of the two combined bodies and pre-compact it, with a pressure of 0.04 MPa - 0.08 MPa, to obtain the preformed I-shaped floor beam;

[0050] S33. Lay the upper flange 14 and the lower flange 15 of the variable cross-section I-shaped floor beam. The upper flange 14 and the lower flange 15 adopt the automatic tape laying or manual laying process. Lay the upper flange 14 on the bottom surface of the upper cover die 1, and lay the lower flange 15 on the upper surface of the lower cover die 2. As Figure 6 and Figure 7 shown

[0051] The upper cover die 1 is made of carbon fiber composite material, glass fiber composite material or metal.

[0052] S4. Combine the lower flange 15 with the preformed I-shaped floor beam;

[0053] S41. Install a plurality of side support columns 3 on the two side edges of the lower cover die 2, and install a soft die web positioning pin 4 on the front edge of the lower cover die 2; if multiple variable cross-section I-shaped floor beams need to be manufactured simultaneously, multiple soft die web positioning pins 4 need to be installed on the lower cover die 2.

[0054] S42. Lift and install the preformed I-shaped floor beam onto the lower cover die 2, and complete the positioning of the preformed I-shaped floor beam and the combination of the preformed I-shaped floor beam and the lower flange 15 through the positioning holes on the C-shaped beam preforming die 12 and the lower cover die 2. If multiple variable cross-section I-shaped floor beams need to be manufactured simultaneously, multiple preformed I-shaped floor beams need to be lifted and installed onto the lower cover die 2.

[0055] S5. Place the cylindrical rubber sandwich soft die 6 and the hollow metal core die 17 in the notch of the preformed C-shaped beam 13; as Figure 7 shown

[0056] S51. Place the tubular vacuum bag into the cylindrical rubber sandwich soft mold 6, remove the C-beam preforming mold 12 in S4, and connect the cylindrical rubber sandwich soft mold 6 in the notch of the preformed C-beam 13 through the soft mold positioning plate 5 and the soft mold web positioning pin 4 on the lower edge strip 15;

[0057] S52. Place the hollow metal core mold 17 into the tubular vacuum bag from both ends respectively, and complete the positioning of the hollow metal core mold 17 by connecting the metal core mold web positioning plate 18 with the soft mold positioning plate 5.

[0058] S6. Complete the mold combination of the upper cover plate mold 1 and the lower cover plate mold 2; as Figure 8 shown.

[0059] Lift the upper cover plate mold 1 as a whole, turn it over, and connect it with the side support columns 3 installed on the lower cover plate mold 2 to complete the combination of the upper edge strip 14 of the variable cross-section I-shaped floor beam and the preformed C-beam 13, and at the same time complete the mold combination of the upper cover plate mold 1 and the lower cover plate mold 2.

[0060] S7. Evacuate the tubular vacuum bag in the cavity of the cylindrical rubber sandwich soft mold 6 and cure the entire device;

[0061] Use putty strips to closely attach the side of the tubular vacuum bag in the cavity of the cylindrical rubber sandwich soft mold 6, and then connect it with the external vacuum bag to evacuate; the vacuum degree should reach at least -0.06~-0.09MPa. After stabilizing for 15 minutes, close the vacuum source. If the vacuum degree drops by no more than 0.017MPa within 5 minutes, it can enter the autoclave for curing.

[0062] If multiple variable cross-section I-shaped floor beams are manufactured, connect all the tubular vacuum bags and evacuate.

[0063] S8. Demold to obtain the variable cross-section I-shaped floor beam.

[0064] S81. Remove the upper cover plate mold 1, remove the side support columns 3 and the soft mold web positioning pin 4, turn it over 180° as a whole, and then remove the lower cover plate mold 2;

[0065] S82. Withdraw the hollow metal core mold 17 from both ends, and then withdraw the cylindrical rubber sandwich soft mold 6 to complete demolding and obtain the variable cross-section I-shaped floor beam.

[0066] It will be understood that the present invention is described by way of some embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teaching of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A manufacturing method of a cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam, characterized in that: It includes the following steps: S1. Fabricate an integral cylindrical rubber sandwich soft mold (6), and control the internal surface of the variable cross-section I-shaped floor beam through the external surface of the cylindrical rubber sandwich soft mold (6); S2. Customize a hollow metal core mold (17), which can provide support during the curing of the preformed C-shaped beam (13); S3. Prepare a preform of the I-shaped floor beam; S4. Combine the lower flange (15) with the preform of the I-shaped floor beam; S5. Place the cylindrical rubber sandwich soft mold (6) and the hollow metal core mold (17) in the notch of the preformed C-shaped beam (13); S6. Complete the mold combination of the upper cover mold (1) and the lower cover mold (2); S7. Vacuum the tubular vacuum bag in the cavity of the cylindrical rubber sandwich soft mold (6) and cure the entire device; S8. Demold to obtain the variable cross-section I-shaped floor beam; The specific steps of the above S1. Fabricating the integral cylindrical rubber sandwich soft mold (6) are as follows: Use a rubber soft mold forming mold to injection mold the cylindrical rubber sandwich soft mold (6) through injection molding. The cylindrical rubber sandwich soft molds (6) are used in combination to form multiple closed cavities, enabling the single-time molding of multiple "I-shaped" beams; Or the specific steps of the above S1. Fabricating the integral cylindrical rubber sandwich soft mold (6) are as follows: S11. Manually lay and stack the uncured rubber layer (9) in the female mold (8) of the soft mold forming, and perform vacuum compaction; S12. Continuously lay and stack the carbon fiber sandwich layer (7) on the uncured rubber layer (9), and perform vacuum compaction; S13. Continuously lay and stack another uncured rubber layer (9) on the uncured rubber layer (9) and the carbon fiber sandwich layer (7), and compact it using a vacuum bag; S14. According to steps S11 - S13, stack another set of sandwich rubber soft molds; S15. Flip the stacked two sets of sandwich rubber soft molds and the forming mold, close the mold, encapsulate, cure in an autoclave, and demold to obtain the integral cylindrical rubber sandwich soft mold (6).

2. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 1, characterized in that: The carbon fiber sandwich layer (7) adopts a form that is continuous in length and segmented in configuration, and the laying of the carbon fiber sandwich layer (7) is cancelled at the rounded corners of the cylindrical rubber sandwich soft mold (6).

3. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 1, characterized in that: The specific steps of the above S3. Preparing the preform of the I-shaped floor beam are as follows: S31. Adopt the automatic tape laying process to complete the laying of the flat sheet (11); S32. Transform the flat sheet (11) into the preformed C-shaped beam (13), and manufacture two preformed C-shaped beams (13) on the left and right; S32. Combine the two preformed C-shaped beams (13) on the left and right, and place the caulking strips (16) at the upper and lower notches of the two combined bodies to obtain the preform of the I-shaped floor beam; S33. Lay the upper flange (14) on the bottom surface of the upper cover mold (1), and lay the lower flange (15) on the upper surface of the lower cover mold (2).

4. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 3, characterized in that: The specific steps of the above S4. Combining the lower flange (15) with the preform of the I-shaped floor beam are as follows: S41. Install multiple side support columns (3) on both side edges of the lower cover mold (2), and install a soft mold web positioning pin (4) on the front edge of the lower cover mold (2); S42. Hoist the I-shaped floor beam preform onto the lower cover die (2), and complete the positioning of the I-shaped floor beam preform and the combination of the I-shaped floor beam preform and the lower flange (15) by connecting through the positioning holes on the C-shaped beam preforming die (12) and the lower cover die (2).

5. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 4, characterized in that: The specific steps of the described S5. for placing the cylindrical rubber sandwich soft die (6) and the hollow metal core die (17) into the notch of the preformed C-shaped beam (13) are as follows: S51. Place the tubular vacuum bag into the cylindrical rubber sandwich soft die (6), remove the C-shaped beam preforming die (12) in S4, and connect the cylindrical rubber sandwich soft die (6) in the notch of the preformed C-shaped beam (13) through the soft die positioning plate (5) and the soft die web positioning pin (4). S52. Place the hollow metal core die (17) into the tubular vacuum bag from both ends respectively, and complete the positioning of the hollow metal core die (17) by connecting through the metal core die web positioning plate (18) and the soft die positioning plate (5).

6. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 5, characterized in that: The specific steps of the described S6. for completing the die combination of the upper cover die (1) and the lower cover die (2) are as follows: Hoist the upper cover die (1) as a whole, turn it over, and connect it to the side support columns (3) installed on the lower cover die (2) to complete the combination of the upper flange (14) and the preformed C-shaped beam (13), and at the same time complete the die combination of the upper cover die (1) and the lower cover die (2).

7. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 6, characterized in that: The specific steps of the described S7. for evacuating the tubular vacuum bag in the cavity of the cylindrical rubber sandwich soft die (6) and curing the entire device are as follows: Use putty strips to closely attach the side of the tubular vacuum bag in the cavity of the cylindrical rubber sandwich soft die (6), then connect it to the external vacuum bag, evacuate the air, and then enter the autoclave for curing.

8. The manufacturing method of the cylindrical rubber sandwich soft mold assisted variable cross-section composite material floor beam according to claim 7, characterized in that: The specific steps of S8. for demolding to obtain the variable cross-section I-shaped floor beam are as follows: S81. Remove the upper cover die (1), remove the side support columns (3) and the soft die web positioning pin (4), turn it over 180° as a whole, and then remove the lower cover die (2). S82. Withdraw the hollow metal core die (17) from both ends, and then withdraw the cylindrical rubber sandwich soft die (6), and the demolding is completed to obtain the variable cross-section I-shaped floor beam.

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