A composite material special-shaped closed-cavity structural part forming tool and use method

Abstract

The present invention belongs to the technical field of composite material processing and forming, and discloses a composite material special-shaped closed-cavity structural component forming tool and a method of use. An air bag with built-in foam support is used to replace the previous metal tool as a structural component stacking mold, which facilitates the stacking and turnover of the structural component. After the structural component is combined with the forming tool, the foam is destroyed and removed, which is equivalent to pressurizing the structural component through the built-in air bag when it is solidified. The inner mold cavity of the structural component forming tool is the forming reference, and the pressure transmission during the solidification process of the structural component is more uniform, and the surface quality of the part is better. It has the characteristics of light material, easy operation, low manufacturing cost, and a wide range of applications.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material processing and forming, and relates to a composite material special-shaped closed-cavity structural component forming tool and a use method. Background Art

[0002] With the continuous development of the aviation industry, composite materials products have evolved from the initial small and secondary load-bearing structural parts to the main load-bearing structural parts, making outstanding contributions to aircraft weight reduction and comprehensive performance improvement. The use of composite materials has become one of the important indicators to measure the advancement of aircraft.

[0003] Composite material special-shaped closed-cavity structural parts refer to parts with closed structures on the surface, such as tubular structures, air intake duct structures, etc. This type of structural parts is different from the previous state with open structural parts, such as plane structural parts or curved structural parts. Open structural parts are easy to stack and package, while special-shaped closed-cavity structural parts are not easy to stack and package at the closed-cavity structure, especially slender closed-cavity structures. The internal closed-cavity structure is more difficult to handle.

[0004] There are two main manufacturing methods currently used to solve the manufacturing difficulties of composite special-shaped closed-cavity structural parts. The first solution is to directly stack them inside the female mold, and then package the inner and outer surfaces of the structural parts as a whole; the second solution is to complete the stacking process of the structural parts on the metal male mold tooling, transfer the structural parts and the tooling as a whole to the female mold forming mold, and then package the structural parts after taking out the metal male mold. The above two solutions can achieve good results when the appearance of the structural parts is relatively regular, but there are still certain limitations for special-shaped structural parts. For the first solution, the stacking process is carried out inside the mold, which makes it difficult to observe the angle of the fiber, which is easy to cause fiber angle deviation, and for some closed-cavity structural parts with longer lengths, the stacking operation cannot be performed at the far end; for the second solution, the structural parts are first stacked on the metal male mold tooling, and the metal male mold tooling needs to be taken out after being combined with the female mold tooling. If the closed-cavity structural part has a curvature, the metal male mold tooling will not be able to be separated from the structural part. In addition, when the above two solutions are used to package structural parts, it is difficult to avoid transferring the wrinkles of the vacuum bag to the surface of the part by directly packaging the vacuum bag because it is not easy to place a conforming auxiliary cover plate in the closed cavity structure. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a molding tool for manufacturing composite material special-shaped closed-cavity structural parts by using a manual lay-up-autoclave curing method, which can avoid the above disadvantages and improve the manufacturing quality of parts.

[0006] A composite material special-shaped closed-cavity structural component forming tooling comprises a forming die lower die 2 and a forming die upper die 3, wherein the forming die lower die 2 is provided with a glue retaining groove 9, and a transition slope 1 is arranged at the root of the forming die lower die 2; a hanging ring 5 is arranged on the upper side of the forming die upper die 3; positioning mechanisms are respectively arranged on the outer side of the forming die lower die 2 and the outer side of the forming die upper die 3, and the forming die lower die 2, the forming die upper die 3 and the positioning mechanism are threadedly connected by bolts 4.

[0007] Further features, the positioning mechanism is an upper mold length direction positioner 6, a lower mold length direction positioner 7 and a mold width direction positioner 8.

[0008] Further features include that the sharp corners of the composite material special-shaped closed-cavity structural parts forming tooling are rounded, the surface roughness requirements are Ra1.6, Ra0.8, Ra0.4, the profile tolerance is ±0.1mm, and the hole position tolerance of the pin hole is ±0.05mm.

[0009] A further feature is that the angle between the transition slope 1 and the bottom surface is 30° to 45°.

[0010] A method for using a composite material special-shaped closed-cavity structural component forming tooling comprises the following steps:

[0011] Step 1: Foam Processing

[0012] Select foam materials, splice them into blanks of sufficient size by gluing, perform CNC milling on the blanks, ensure that the two ends of the foam 11 after milling are 150-200mm longer than the actual size of the parts, and the overall profile is 3mm smaller than the actual size of the parts;

[0013] Step 2: Lay up the airbag

[0014] Lay two layers of rubber on the surface of the processed foam 11, and the lamination range covers the entire outer surface of the foam 11;

[0015] Step 3: Airbag forming and trimming

[0016] The foam 11 and the rubber are packaged in a vacuum bag, and the airbag is formed by using an autoclave, and the formed hollow airbag 10 wraps the foam 11; the surface of the hollow airbag 10 is trimmed to make the surface smooth; and a layer of Tooltec isolation material 12 is laid on the surface of the hollow airbag 10;

[0017] Step 4: Lay up the parts

[0018] Laying composite material parts 13 on the outer surface of Tooltec isolation material 12, performing vacuum compaction and ensuring the laying angle according to technical requirements;

[0019] Step 5: Preparing the molding tool

[0020] Degreasing and cleaning the lower mold 2 and the upper mold 3 of the molding mold are performed respectively, and a mold release agent is applied to the inner mold cavity surfaces of the lower mold 2 and the upper mold 3 of the molding mold, and the tooling is transferred to the clean room using the lifting ring 5;

[0021] Step 6: Parts Transfer

[0022] The laminated composite part 13 is transferred together with the hollow airbag 10, the foam 11 and the Tooltec insulating material 12 to the lower mold 2 of the molding mold;

[0023] Step 7: Tooling Assembly

[0024] The tooling assembly is completed by using the positioning mechanisms on the lower die 2 and the upper die 3 of the forming die;

[0025] Step 8: Overall packaging

[0026] The foam 11 is destroyed, the foam 11 residue inside the hollow airbag 10 is cleaned, and the lower mold 2 and the upper mold 3 of the molding mold are integrally encapsulated in a vacuum bag.

[0027] A further feature is that the value of the reduction in the profile size of the foam 11 is appropriately adjusted according to the wall thickness of the hollow airbag 10 .

[0028] Beneficial effects:

[0029] (1) The present invention uses an air bag with built-in foam support to replace the previous metal tooling as a part stacking mold. It has the characteristics of light material and easy operation, which is convenient for the stacking and turnover of parts. After the parts are combined with the molding tooling, the foam is destroyed and removed, which is equivalent to pressurizing the parts through the built-in air bag when they are solidified. The inner mold cavity of the part molding tooling is the molding reference. The pressure transmission during the part solidification process is more uniform and the surface quality of the parts is better.

[0030] (2) The foam used for parts manufacturing can be sourced from leftover scraps and scrapped materials at the production site, with low manufacturing costs. Moreover, the foam can be cut by CNC milling to ensure shape and precision, and can be highly matched with the shape of the parts, thus having a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of composite material special-shaped closed-cavity structural parts.

[0032] Figure 2 It is an overall schematic diagram of the molding tooling for composite material special-shaped closed-cavity structural parts.

[0033] Figure 3 This is a schematic diagram of the lower die of the molding die for the molding tooling of composite material special-shaped closed-cavity structural parts.

[0034] Figure 4Schematic diagram of the process plan for composite material special-shaped closed-cavity structural parts.

[0035] In the figure: 1 transition slope; 2 lower die of forming die; 3 upper die of forming die; 4 bolt; 5 lifting ring;

[0036] 6 Upper die length direction locator; 7 Lower die length direction locator; 8 Die width direction locator;

[0037] 9: adhesive retaining groove; 10: hollow airbag; 11: foam; 12: Tooltec isolation material;

[0038] 13 composite material special-shaped closed cavity structural part; 14 lifting ring connection hole; 15 bolt connection hole; 16 inner mold cavity. DETAILED DESCRIPTION

[0039] The specific implementation method of the present invention is described below in conjunction with the accompanying drawings and technical solutions.

[0040] As shown in the figure, the molding tooling for composite material special-shaped closed-cavity structural parts is made of ordinary steel and has a female mold structure, including a transition slope 1, a molding mold lower mold 2, a molding mold upper mold 3, bolts 4, a lifting ring 5, an upper mold length direction locator 6, a lower mold length direction locator 7, a mold width direction locator 8 and a glue retaining groove 9; the main body is composed of a molding mold lower mold 2 and a molding mold upper mold 3. The inner mold cavity 16 formed by the upper and lower combination of the two is the working surface for part molding. During curing, the tooling inner mold cavity 16 penetrates into the hollow airbag 10, and the part is located between the hollow airbag 10 and the tooling inner mold cavity 16 for molding.

[0041] The molding tool for composite material special-shaped closed-cavity structural parts is used for the packaging and curing of composite material closed-cavity structural parts. Sharp corners need to be rounded, the surface roughness requirement is Ra1.6 (or Ra0.8, Ra0.4, etc.), the profile tolerance is ±0.1mm, and the hole position tolerance of each pin hole is ±0.05mm.

[0042] The lifting ring 5 is used for the logistics turnover and assembly of the forming tooling of composite material special-shaped closed-cavity structural parts.

[0043] The transition slope 1 has an angle of 30° to 45° with the bottom surface and is placed at the root of the end of the composite material special-shaped closed-cavity structural component molding tooling to place the hollow airbag 4 extending from the inside of the composite material special-shaped closed-cavity structural component molding tooling cavity.

[0044] A glue-blocking groove 9 is designed on the lower mold 2 of the molding mold. Its cross-section is a square with a side length of 5-8 mm. The length varies with the size of the main molding mold and is located 10-15 mm away from the inner mold cavity of the main tooling. The glue-blocking groove 9 is filled with glue-blocking material when the composite material special-shaped closed-cavity structural parts are cured to prevent excessive loss of resin in the composite material special-shaped closed-cavity structural parts.

[0045] The thickness of the upper mold length direction locator 6 and the lower mold length direction locator 7 is 10-20mm. They are located on both sides of the width direction of the composite material special-shaped closed-cavity structural component molding tooling and are fixed to the composite material special-shaped closed-cavity structural component molding tooling with bolts and pins. They are used to position the lower mold 2 and the upper mold 3 when the molding mold is combined to ensure the matching accuracy.

[0046] The thickness of the mold width direction locator 8 is 10-20mm. The thickness and weight can be appropriately reduced while ensuring the rigidity. It is fixed to the main molding mold with bolts. When the molding mold lower mold 2 and the molding mold upper mold 3 are combined, the four mold width direction locators 8 located at both ends of the main molding mold are used for combined positioning to ensure the accuracy in the width direction when the molding mold lower mold 2 and the molding mold upper mold 3 are combined.

[0047] When the lower die 2 and the upper die 3 of the forming die are assembled, the bolts 4 evenly distributed on the upper die 2 of the forming die are used to tighten the two.

[0048] The method for using the composite material special-shaped closed-cavity structural component forming tooling includes the following steps:

[0049] (1) Foam processing: Select foam materials and splice them into blanks of sufficient size by gluing. CNC milling is performed on the blanks with reference to the size of the parts to ensure that the two ends of the foam 11 after milling are 150-200 mm longer than the actual size of the parts, and the overall profile is 3 mm smaller than the actual size of the parts (the reduction value can be appropriately adjusted with reference to the wall thickness of the hollow airbag 10).

[0050] (2) Airbag stacking: Two layers of rubber (brand: AIRPAD) are stacked on the surface of the processed foam 11, and the stacking range needs to cover the entire outer surface of the foam 11 (except the rectangular and circular opening areas at the two ends).

[0051] (3) Airbag molding and trimming: The foam 11 and rubber are packaged in a vacuum bag. Note that to ensure the surface quality of the airbag, the vacuum bag should not be wrinkled as much as possible. The airbag is molded using an autoclave. The molded hollow airbag 10 is wrapped with the foam 11. The surface of the hollow airbag 10 is trimmed to make it smooth without pits and protrusions. Finally, a layer of Tooltec isolation material 12 is laid on the surface of the hollow airbag 10 (to isolate the parts from the airbag so that the two cannot come into direct contact).

[0052] (4) Part stacking: stack the composite part 13 on the outer surface of the Tooltec isolation material 12, paying attention to vacuum compaction and ensuring the stacking angle according to technical requirements.

[0053] (5) Preparation of molding tooling: Degrease and clean the lower mold 2 and the upper mold 3 of the molding mold respectively, apply a mold release agent to the inner mold cavity surface of the lower mold 2 and the upper mold 3 of the molding mold, and use the lifting ring 5 to transfer the tooling to the clean room.

[0054] (6) Part transfer: The laminated composite part 13 together with the hollow airbag 10, the foam 11 and the Tooltec insulating material 12 are transferred to the lower mold 2 of the molding mold.

[0055] (7) Tool assembly: The tool assembly is completed using the positioning mechanism and the connecting mechanism on the molding tool (at this time, the composite material part 13 is located inside the tool).

[0056] (8) Overall packaging: destroy the foam 11 inside the part, clean the foam 11 residue inside the hollow airbag 10, and package the tooling in a vacuum bag. Leave the two ends of the hollow airbag 10 outside the vacuum bag so that high-pressure gas can enter the hollow airbag 10 during curing to pressurize the part. After the curing and packaging is completed, the final product needs to be obtained according to the process of "curing-demolding-exterior processing-inspection".

Claims

1. A method for using a molding tool for composite material special-shaped closed-cavity structural parts, characterized in that: The steps include: Step 1: Foam Processing Select foam materials, splice them into blanks of sufficient size by gluing, perform CNC milling on the blanks, ensure that the two ends of the foam (11) after milling are respectively 150-200 mm longer than the actual size of the parts, and the overall profile is 3 mm smaller than the actual size of the parts; Step 2: Lay up the airbag Laying two layers of rubber on the surface of the processed foam (11), with the laminating range covering the entire outer surface of the foam (11); Step 3: Airbag forming and trimming The foam (11) and rubber are packaged in a vacuum bag, and an airbag is formed by using an autoclave, and the formed hollow airbag (10) is wrapped with the foam (11); the surface of the hollow airbag (10) is trimmed to make the surface smooth; and a layer of Tooltec isolation material (12) is laid on the surface of the hollow airbag (10); Step 4: Lay up the parts Laying composite material parts (13) on the outer surface of Tooltec isolation material (12), performing vacuum compaction according to technical requirements and ensuring the laying angle; Step 5: Preparing the molding tool The molding tool comprises a molding die lower die (2) and a molding die upper die (3); a rubber retaining groove (9) is provided on the molding die lower die (2), and a transition slope (1) is arranged at the root of the molding die lower die (2); a lifting ring (5) is arranged on the upper side of the molding die upper die (3); positioning mechanisms are respectively arranged on the outer side of the molding die lower die (2) and the outer side of the molding die upper die (3); the molding die lower die (2), the molding die upper die (3) and the positioning mechanism are threadedly connected by bolts (4); the positioning mechanism comprises an upper die length direction positioner (6), a lower die length direction positioner (7) and a mold width direction positioner (8); Degreasing and cleaning the lower mold (2) and the upper mold (3) of the molding mold are performed respectively, and a mold release agent is applied to the inner mold cavity surfaces of the lower mold (2) and the upper mold (3) of the molding mold, and the tooling is transferred to the clean room using a lifting ring (5); Step 6: Parts Transfer Transferring the laminated composite material part (13) together with the hollow airbag (10), the foam (11), and the Tooltec insulating material (12) into the lower mold (2) of the molding mold; Step 7: Tooling Assembly The tooling assembly is completed by using the positioning mechanisms on the lower mold (2) and the upper mold (3) of the molding mold; Step 8: Overall packaging The foam (11) is destroyed, the foam (11) residue inside the hollow airbag (10) is cleaned, and the lower mold (2) and the upper mold (3) are integrally encapsulated in a vacuum bag.

2. The method for using the molding tool for composite material special-shaped closed-cavity structural parts according to claim 1, characterized in that: The sharp corners of the molding tool are rounded, the surface roughness requirements are Ra1.6, Ra0.8, Ra0.4, the profile tolerance is ±0.1mm, and the hole position tolerance of the pin hole is ±0.05mm.

3. The method for using the molding tool for composite material special-shaped closed-cavity structural parts according to claim 1 or 2, characterized in that: The angle between the transition slope (1) and the bottom surface is 30° to 45°.

4. The method for using the molding tool for composite material special-shaped closed-cavity structural parts according to claim 1, characterized in that: The value of the reduction in the profile size of the foam (11) is appropriately adjusted according to the wall thickness of the hollow airbag (10).

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