Molding tool and inside-outside flange column section structure composite cabin section molding method

Abstract

The application discloses a forming tool and a forming method of an inside-out and outside-in flange column section structure composite material cabin section. The forming tool comprises a core cylinder, support shafts, a male die, a metal fixing plate and a female die assembly. The two support shafts are connected to the axial two ends of the core cylinder respectively. The male die is connected to the cylinder surface of the core cylinder in a ring shape. The metal fixing plate is connected to the outer circumferential surface of the male die in a ring shape. The female die assembly comprises a metal cover plate, a first process skin and a second process skin. The metal cover plate is connected with the metal fixing plate and encloses the metal fixing plate to form an outside-in flange cavity. The metal cover plate can float in the axial and radial directions of the core cylinder. The first process skin is used for enclosing an axial end of the male die away from the metal fixing plate to form an inside-in flange cavity. The second process skin is used for being arranged on the male die and enclosing the male die to form a column section cavity. The outside-in flange cavity, the column section cavity and the inside-in flange cavity are sequentially communicated. The application reduces the internal quality risk of the product, can effectively reduce the manufacturing cost and heat sink of the female die and improves the heat transfer efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material forming, in particular to a forming tool and a method for forming a composite material cabin section with an inside-outside flange column structure. BACKGROUND

[0002] Carbon fiber reinforced resin-based composite materials have become the main load-bearing structure materials in the field of aerospace. With the development of science and technology, the structure of the materials has gradually developed from simple to complex. Most carbon fiber cabin sections are manufactured by the autoclave forming method.

[0003] In the field of aerospace, composite material cabin sections require high-quality inner and outer shapes, such as an inside-outside flange column structure with an outside flange on one side and an inside flange on the other side. In order to facilitate laying and forming, a forming method is adopted, in which a preform is laid and pre-pressed on a convex mold, and then a metal concave mold is installed for shape maintenance and curing. However, the tooling form in this forming method cannot guarantee the close fit between the preform and the metal concave mold, and the inside-outside flange column structure produced by the tooling form has certain internal quality risks. SUMMARY

[0004] To solve the above problems, the present application provides a forming tool and a method for forming a composite material cabin section with an inside-outside flange column structure.

[0005] The present application provides a forming tool for forming a composite material cabin section with an inside-outside flange column structure. The forming tool includes a core barrel, a support shaft, a convex mold, a metal fixing plate, and a concave mold assembly. Two support shafts are oppositely arranged, and are respectively connected to the axial ends of the core barrel. The convex mold is connected around the barrel surface of the core barrel. The metal fixing plate is connected around the outer surface of the convex mold. The concave mold assembly includes a metal cover plate, a first process skin, and a second process skin. The metal cover plate is connected with the metal fixing plate and enclosed with the metal fixing plate to form an outside flange cavity. The metal cover plate can float in the axial and radial directions of the core barrel. The first process skin is used to enclose the axial end of the convex mold away from the metal fixing plate to form an inside flange cavity. The second process skin is used to enclose around the convex mold to form a column cavity. The outside flange cavity, the column cavity, and the inside flange cavity are sequentially connected to form a pre-impregnated material accommodating cavity.

[0006] In some embodiments, the metal cover plate, the first process skin, and the second process skin are all annular split structures. The concave mold assembly further includes a plurality of baffles. The baffles are laid on at least one of the inner side of the first process skin, the inner side of the second process skin, and the side of the metal cover plate facing the convex mold. The plurality of baffles are respectively arranged across the gap between the first process skin and the second process skin, the gap between the second process skin and the metal cover plate, the gap between the adjacent two split components of the first process skin, and the gap between the adjacent two split components of the second process skin.

[0007] In some embodiments, the first process skin comprises:

[0008] a cylinder portion, which is opposite to the outer circumferential surface of the male die at a distance, and the second process skin is located between the metal cover plate and the cylinder portion; and

[0009] a ring portion, which is connected to the cylinder portion, and the ring portion is opposite to the axial end of the male die away from the metal fixing plate at a distance, and the ring portion and the male die enclose to form an inverted flange cavity.

[0010] In some embodiments, the male die is a ring split structure, and all split components of the male die are sequentially connected to the outer circumferential surface of the core barrel in the ring direction, and the split components of the male die and the core barrel are connected by pin positioning and screw connection.

[0011] In some embodiments, the male die is provided with a concave-convex surface on the outer periphery.

[0012] In some embodiments, the core barrel is provided with an extension section that extends beyond the distribution area of the male die in the axial direction, and two extension sections are oppositely arranged on both axial sides of the male die.

[0013] The forming tool further comprises a vacuum cladding member, which is used to be sleeved on the male die, the metal fixing plate and the female die assembly, and the two ends of the vacuum cladding member are respectively detachably connected to the two extension sections.

[0014] The support shaft is provided with a gas hole, and the support shaft is provided with a gas channel that communicates with the cylinder cavity of the core barrel.

[0015] A forming method of an inner and outer inverted flange column section structure composite cabin section, which adopts the forming tool described above, and the forming method of the inner and outer inverted flange column section structure composite cabin section comprises:

[0016] The prepreg is laid on the male die and the metal fixing plate, and pre-pressing is performed during the prepreg laying process.

[0017] After the prepreg laying process is completed, the female die assembly and the vacuum cladding member are assembled, and heating, pressing and curing are performed by a hot press tank.

[0018] After the heating, pressing and curing are completed, demolding is performed to obtain the inner and outer inverted flange column section structure composite cabin section.

[0019] In some embodiments, during the prepreg laying process, the pre-pressing includes first normal temperature vacuum pre-pressing after the first layer of laying, intermittent normal temperature vacuum pre-pressing every 4-8 layers of prepreg, and heated vacuum pre-pressing every 2-3 mm thickness of prepreg, and the pre-pressing is performed under the condition of assembling the female die assembly and the vacuum cladding member.

[0020] In some embodiments, during the heating and vacuum pre-pressing process, the uninstalled concave die assembly and the vacuum bagging piece on which the prepreg is laid are placed in an oven, the oven is used as a heat source to form a heating condition, and a vacuum pump is used to create a vacuum between the vacuum bagging piece and the prepreg to form a pressurizing condition.

[0021] In some embodiments, during the demolding process, the intermediate product obtained after demolding is further subjected to post-processing, the post-processing including polishing, testing and reprocessing the intermediate product, and the polished intermediate product is further subjected to testing and processing, the testing including internal quality testing and appearance testing.

[0022] The present application has the following advantages: a molding tool is provided, which is used for molding an inside-out and outside-in flange column segment structure composite material cabin segment, two support shafts are connected to the axial ends of the core cylinder, the core cylinder can rotate through the support shafts, the convex die is connected around the cylinder surface of the core cylinder, the metal fixing plate is connected around the outer peripheral surface of the convex die, the concave die assembly is specially designed, the concave die assembly includes a metal cover plate, a first process skin and a second process skin, the metal cover plate is connected with the metal fixing plate and enclosed with the metal fixing plate to form an outside-in flange cavity, the metal cover plate can float in the axial and radial directions of the core cylinder, the first process skin is used to enclose with the axial end of the convex die away from the metal fixing plate to form an inside-out flange cavity, and the second process skin is used to enclose with the convex die to form a column segment cavity, the outside-in flange cavity, the column segment cavity and the inside-out flange cavity are sequentially communicated to form a prepreg accommodating cavity; in the tooling technology for molding the inside-out and outside-in flange column segment structure composite material cabin segment, the traditional metal concave die is replaced by the concave die assembly including the metal cover plate, the first process skin and the second process skin, the outside-in flange cavity is formed by clamping with the metal cover plate and the metal fixing plate, the inside-out flange cavity is formed by enclosing with the first process skin and the convex die, and the column segment cavity is formed by enclosing with the second process skin and the convex die, during the process of vacuum bagging and curing of the prepreg in the autoclave, the metal cover plate, the first process skin and the second process skin can move slightly with the prepreg, which can ensure that the prepreg is always closely attached to each component in the concave die assembly, thereby reducing the internal quality risk of the product caused by the separation of the prepreg and the metal concave die in the traditional metal concave die mode, overcoming the problem that the product is not easy to form due to the separation of the prepreg and the metal concave die in the traditional metal concave die mode, and ensuring the profile of the product through the concave die assembly in the tool, so that the product has a good appearance; on the other hand, compared with the traditional metal concave die scheme, the concave die assembly including the metal cover plate, the first process skin and the second process skin can effectively reduce the manufacturing cost of the concave die, effectively reduce the heat sink of the concave die, improve the heat transfer efficiency, reduce the energy consumption cost during molding production, and has significant economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application.

[0024] Figure 1 A schematic view of a forming tool provided by the present application when a die assembly is not installed;

[0025] Figure 2 A schematic view of a cross section of a forming tool provided by the present application when a die assembly is not installed;

[0026] Figure 3 A schematic view of a male die in a forming tool provided by the present application;

[0027] Figure 4 A schematic view of a pre-preg between a male die and a die assembly in a forming tool provided by the present application;

[0028] Figure 5 A schematic view of an everted flange cavity, a column segment cavity and an inverted flange cavity in a forming tool provided by the present application;

[0029] Figure 6 A schematic view of an arrangement of a blocking piece in a forming tool provided by the present application;

[0030] Figure 7 A schematic view of another arrangement of a blocking piece in a forming tool provided by the present application;

[0031] Figure 8 A schematic view of a main flow of a method for forming a composite material cabin section with an everted flange column segment structure provided by the present application.

[0032] FIG. 10 is a schematic view of a forming tool provided by the present application when a die assembly is not installed; FIG. 11 is a schematic view of a cross section of a forming tool provided by the present application when a die assembly is not installed; FIG. 12 is a schematic view of a male die in a forming tool provided by the present application; FIG. 13 is a schematic view of a pre-preg between a male die and a die assembly in a forming tool provided by the present application; FIG. 14 is a schematic view of an everted flange cavity, a column segment cavity and an inverted flange cavity in a forming tool provided by the present application; FIG. 15 is a schematic view of an arrangement of a blocking piece in a forming tool provided by the present application; FIG. 16 is a schematic view of another arrangement of a blocking piece in a forming tool provided by the present application; FIG. 17 is a schematic view of a main flow of a method for forming a composite material cabin section with an everted flange column segment structure provided by the present application. DETAILED DESCRIPTION

[0033] The application discloses a forming tool, hereinafter referred to as the tool, which is used for forming a composite cabin section of an inside-outside flange column section structure, in particular through autoclave forming, the inside-outside flange column section structure comprising a cylindrical structure as a main structure, an inside-out flange connected to an axial one end of the cylindrical structure and an outside-out flange connected to an axial other end of the cylindrical structure, and the structure is made of composite materials through an autoclave forming method. In particular, the tool of the application is used for forming a carbon fiber reinforced resin-based composite material, and the formed product belongs to a main load-bearing structure in the field of aerospace.

[0034] Please refer to Figure 1 and Figure 2 , the tool comprises a core cylinder 10 and a support shaft 20, a male die 30 and a metal fixing plate 40. The core cylinder 10 serves as a mounting base of the male die 30, the core cylinder 10 is designed as a cylindrical structure, and the cylinder cavity of the core cylinder 10 is large enough to achieve the effect of sufficient weight reduction. In order to realize the rotatable function of the core cylinder 10, one support shaft 20 is connected to each of the axial two ends of the core cylinder 10, the support shaft 20 can be connected with the core cylinder 10 through screws, the support shaft 20 plays a supporting role and an auxiliary rotating role of the core cylinder 10, and facilitates the layering operation when the pre-impregnated material 70 is laid on the male die 30.

[0035] Please refer to Figure 1 and Figure 2 , the tool comprises the male die 30, the male die 30 is connected to the cylindrical surface of the core cylinder 10 in a surrounding manner, which means that the male die 30 is mounted on the cylindrical surface of the core cylinder 10 and surrounds the cylindrical surface of the core cylinder 10. Generally, the male die 30 is a split ring structure, and a plurality of split ring structures are assembled together to form the male die 30, please refer to Figure 1 and Figure 2 , all split ring members of the male die 30 are distributed along the circumferential direction of the core cylinder 10, and each split ring member of the male die 30 is connected to the outer periphery of the core cylinder 10. In some embodiments, the split ring members of the male die 30 are connected to the core cylinder 10 through a pin positioning and screw connection mode, which can ensure the installation accuracy of the male die 30 on the core cylinder 10.

[0036] Please refer to Figure 1 and Figure 2 , the tool comprises the metal fixing plate 40, the metal fixing plate 40 is connected to the outer peripheral surface of the male die 30 in a surrounding manner, that is, the metal fixing plate 40 surrounds and is connected to the outer peripheral surface of the male die 30, and the metal fixing plate 40 can be connected to the split ring members of the male die 30 through screws. The metal fixing plate 40 provides a layering reference for the outside-out flange.

[0037] When the tool is applied, the pre-impregnated material 70 is first laid on the male die 30 and the metal fixing plate 40 and is pre-pressed, and then the tool is assembled with a female die and is subjected to vacuum curing through an autoclave. It should be noted that Figure 5 only the layering position of the pre-impregnated material 70 is expressed.Figure 5 The use state of the tooling does not belong to the present tooling, by comparison and reference Figure 4 and Figure 5 It is beneficial to understand the groove assembly in the present tooling.

[0038] Please refer to Figure 2 , Figure 4 and Figure 5 , the present tooling includes a die assembly, the die assembly includes a metal cover plate 51, a first process skin 52 and a second process skin 53. The metal cover plate 51 is connected with the metal fixing plate 40, the metal cover plate 51 is spaced from the outer peripheral surface of the punch 30, and the metal cover plate 51 and the metal fixing plate 40 are enclosed to form an outward flange cavity 511. After the molding is completed, the prepreg 70 in the outward flange cavity 511 will form the outward flange of the inner and outward flange column segment structure composite cabin section. The prepreg 70 is laid in the axial end of the punch 30 away from the metal fixing plate 40, the first process skin 52 is attached to the prepreg 70 in the axial end of the punch 30 away from the metal fixing plate 40, which is equivalent to the first process skin 52 being used to enclose the axial end of the punch 30 away from the metal fixing plate 40 to form an inward flange cavity 521. After the molding is completed, the prepreg 70 in the inward flange cavity 521 will form the inward flange of the inner and outward flange column segment structure composite cabin section. Most of the prepreg 70 is laid on the outer peripheral surface of the punch 30, and the second process skin 53 is attached to the prepreg 70 on the outer peripheral surface of the punch 30. At this time, the second process skin 53 surrounds the punch 30 and is spaced from the punch 30. The second process skin 53 arranged outside the punch 30 is enclosed with the punch 30 to form a column segment cavity 531, as shown in Figure 5 , the outward flange cavity 511, the column segment cavity 531 and the inward flange cavity 521 are sequentially communicated to form a prepreg 70 containing cavity.

[0039] In the present tooling, the connection mode of the metal cover plate 51 and the metal fixing plate 40 can realize the axial floating of the metal cover plate 51 along the core barrel 10 and the radial floating of the metal cover plate 51 along the core barrel 10, so as to ensure that the metal cover plate 51 is always attached to the prepreg 70 during the vacuum bag curing process, and the effective pressure on the prepreg 70 is ensured. There are many different implementations of floating connection in the prior art, and in the present application, a scheme for realizing floating connection through a waist-shaped hole is provided, please refer to Figure 1 and Figure 2In the metal fixing plate 40, a plurality of first waist-shaped holes 401 are formed, the length direction of the first waist-shaped hole 401 is the same as the radial direction of the core barrel 10, a first screw is installed in the first waist-shaped hole 401, the first screw is screwed with the metal cover plate 51, the first screw can move in the first waist-shaped hole 401 along the length direction of the first waist-shaped hole 401, so that the metal cover plate 51 can float along the radial direction of the core barrel 10; similarly, the metal cover plate 51 is provided with a second waist-shaped hole 512, the length direction of the second waist-shaped hole 512 is the same as the axial direction of the core barrel 10, a second screw is installed in the second waist-shaped hole 512, the second screw is screwed with the metal fixing plate 40, the second screw can move in the second waist-shaped hole 512 along the length direction of the second waist-shaped hole 512, so that the metal cover plate 51 can float along the axial direction of the core barrel 10; please refer to Figure 1 The metal cover plate 51 is designed as a ring-shaped split structure, a plurality of split components to which the metal cover plate 51 belongs are distributed along the ring direction of the punch 30 in sequence, and each split component to which the metal cover plate 51 belongs is connected with the metal fixing plate 40.

[0040] In the tooling technology for forming the composite material cabin section with the inside-out flange column section structure, in the technical scheme of the tooling, the traditional metal concave die is replaced by a concave die assembly including the metal cover plate 51, the first process skin 52 and the second process skin 53, the outside-out flange cavity 511 is formed by clamping the metal cover plate 51 and the metal fixing plate 40, the inside-out flange cavity 521 is formed by surrounding the first process skin 52 and the punch 30, and the column section cavity 531 is formed by surrounding the second process skin 53 and the punch 30, in the process of vacuum curing of the prepreg 70 in the autoclave, the metal cover plate 51, the first process skin 52 and the second process skin 53 can move slightly with the prepreg 70, so as to ensure that the prepreg 70 is always tightly attached to each component in the concave die assembly, thereby reducing the internal quality risk of the product caused by the separation of the prepreg 70 from the metal concave die in the traditional metal concave die mode, overcoming the problem that the product is not easy to form due to the separation of the prepreg 70 from the metal concave die in the traditional metal concave die mode, and ensuring the profile of the product through the concave die assembly in the tooling, so that the product has a good appearance.

[0041] On the other hand, compared with the traditional metal concave die scheme, the concave die assembly including the metal cover plate 51, the first process skin 52 and the second process skin 53 in the scheme of the present application can effectively reduce the manufacturing cost of the concave die, effectively reduce the heat sink of the concave die, improve the heat transfer efficiency, reduce the energy consumption cost during forming production, and has significant economic benefits.

[0042] In some embodiments, the first process skin 52 is a split structure in the hoop direction, and there is a gap between two adjacent split components of the first process skin 52 in the hoop direction, so as to ensure that the first process skin 52 is always closely attached to the prepreg 70 during the bag vacuum curing process; similarly, the second process skin 53 is a split structure in the hoop direction, and there is a gap between two adjacent split components of the second process skin 53 in the hoop direction, so as to ensure that the second process skin 53 is always closely attached to the prepreg 70 during the bag vacuum curing process.

[0043] Corresponding to the gap between two adjacent split components of the first process skin 52 in the hoop direction, the die assembly includes a plurality of blocking pieces 54, which are laid on the inner side of the first process skin 52, where the inner side of the first process skin 52 refers to the side of the first process skin 52 that is attached to the prepreg 70, which can be referred to Figure 7 (Although Figure 7 the second process skin 53 is marked in the figure, it can also be understood by referring to the figure), the blocking pieces 54 are arranged across the gap between the two adjacent split components of the first process skin 52.

[0044] Similarly, corresponding to the gap between two adjacent split components of the second process skin 53 in the hoop direction, the die assembly includes a plurality of blocking pieces 54, which are laid on the inner side of the second process skin 53, where the inner side of the second process skin 53 refers to the side of the second process skin 53 that is attached to the prepreg 70, which can be referred to Figure 7 , the blocking pieces 54 are arranged across the gap between the two adjacent split components of the second process skin 53.

[0045] Please refer to Figure 4 and Figure 5 , the first process skin 52 and the second process skin 53 are spaced apart, and the die assembly includes blocking pieces 54, which can be referred to Figure 6 , the blocking pieces 54 are laid on the inner side of the first process skin 52 and the inner side of the second process skin 53, and the blocking pieces 54 are arranged across the gap between the first process skin 52 and the second process skin 53.

[0046] Similarly, please refer to Figure 4 and Figure 5 , the second process skin 53 and the metal cover plate 51 are spaced apart, and the die assembly includes blocking pieces 54, which are laid on the side of the metal cover plate 51 facing the punch 30 and the inner side of the second process skin 53, and the blocking pieces 54 are arranged across the gap between the second process skin 53 and the metal cover plate 51.

[0047] In the tooling of the present application, the blocking piece 54 has certain rigidity and certain deformation capacity, which can not only guarantee the profile of the product, but also meet the purpose of being attached to the prepreg 70. During the vacuum curing process, both the blocking piece 54 and the process skin are deformed. Therefore, the material and specifications of the blocking piece 54 need to be considered in actual production, for example, a steel strip with a thickness of 0.1 mm is used as the blocking piece 54, and the thickness of the blocking piece 54 is controlled to a very small degree of 0.1 mm-0.2 mm. This scheme has been verified by actual production.

[0048] When installing the first process skin 52, the second process skin 53 and the plurality of blocking pieces 54, auxiliary means can be used to simplify the installation process. For example, an adhesive tape is used to simultaneously bond all the circumferentially distributed split components of the first process skin 52 and the blocking pieces at the gaps between adjacent two split components, and then the first process skin 52, the corresponding blocking pieces and the adhesive tape are placed together on the outside of the prepreg.

[0049] Regarding the process skin, different materials such as glass steel and carbon fiber composite materials can be used, which have been verified by actual production.

[0050] In some embodiments, referring to Figure 4 , the first process skin 52 includes a cylindrical portion 522 and a ring portion 523, the ring portion 523 is connected to one end of the cylindrical portion 522 in the axial direction, the ring portion 523 is distributed in the plane of the axial cross section of the cylindrical portion 522, the outer diameter of the ring portion 523 is equal to the outer diameter of the cylindrical portion 522, the inner diameter of the ring portion 523 is significantly smaller than the inner diameter of the cylindrical portion 522, the cylindrical portion 522 is spaced from the outer circumferential surface of the punch 30, and the ring portion 523 is spaced from the end of the punch 30 away from the metal fixing plate 40, so that the ring portion 523 and the punch 30 enclose to form an inverted flange cavity 521. After the forming is completed, the prepreg 70 in the inverted flange cavity 521 will form an inverted flange of the inverted flange column structure composite cabin section. Correspondingly, as shown in Figure 4 , the second process skin 53 is located between the metal cover plate 51 and the cylindrical portion 522.

[0051] The above describes the use of the tooling for the forming of the inverted flange column structure composite cabin section. In the technical field of composite cabin sections in the aerospace field, an inner wide rib + inverted flange column structure is involved, and the tooling can be further used for the forming of the inverted flange column structure composite cabin section. Please refer to Figure 1 and Figure 3 , the punch 30 is provided with a concave-convex surface 31 at the outer periphery. By laying the prepreg 70 on the punch 30 and then vacuum curing, the concave-convex surface 31 can be used to produce a composite cabin section with an inner wide rib. The concave-convex surface 31 must be designed according to the actual product shape.

[0052] In some implementation methods, please refer to Figure 1 and Figure 2 The core cylinder 10 is provided with an extension section 11 that extends axially beyond the distribution area of ​​the punch 30. Two extension sections 11 are provided opposite each other and are located on the axial sides of the punch 30. The forming tooling also includes a vacuum covering component 60, which is generally a vacuum bag film. The two ends of the vacuum covering component 60 are detachably connected to the two extension sections 11, and the vacuum covering component 60 is sleeved on the outside of the punch 30, the metal fixing plate 40 and the die assembly. The support shaft 20 is provided with an air hole 21. The support shaft 20 is provided with a channel for the air hole 21 and the cylinder cavity of the core cylinder 10. Hot air can enter the interior of the core cylinder 10 through the air hole 21.

[0053] In the step of laying the prepreg 70 onto the punch 30, the prepreg 70 needs to be pre-compressed, which is achieved by heating and vacuuming. Compared with the traditional vacuum bag covering tooling solution, the solution in this application, which uses the above-mentioned extension 11, vacuum covering part 60 and air hole 21, allows heat flow to enter the core cylinder 10 through the air hole 21, thereby realizing heat transfer to the prepreg 70 from both the inside and outside of the tooling, effectively improving heat transfer efficiency.

[0054] This invention also provides a method for molding composite material compartments with inward and outward flange column segments. By using the above-mentioned molding tooling, composite material compartments with inward and outward flange column segments can be produced. When the outer periphery of the punch 30 is designed with concave and convex surfaces 31, composite material compartments with inner wide ribs and inward and outward flange column segments can also be produced. Figure 8 This paper demonstrates the basic steps of the method, which sequentially includes the prepreg 70 integral layup and pre-compression step, the product packaging vacuum curing step, the demolding step, and the inspection and processing steps. In the prepreg 70 integral layup and pre-compression step, the prepreg 70 is laid up on the tooling, specifically on the punch and the metal fixing plate, and pre-compression is performed during the layup process. In the product packaging vacuum curing step, the die assembly and the vacuum-encased component 60 are assembled first, and then heated and pressurized for curing in an autoclave. In the demolding step, demolding is performed to obtain the intermediate product. In the inspection and processing steps, the product undergoes internal quality and appearance inspections, and the intermediate product is processed, including but not limited to machining the flange holes of the inward and outward flanges, ensuring the flange flatness and overall height dimensions, to obtain the composite material compartment segment of the inward and outward flange column structure that meets the product requirements.

[0055] Before using the tooling, it needs to be cleaned and treated with a release agent to ensure that subsequent demolding can proceed smoothly.

[0056] The following section further designs the overall layup and pre-compression steps of the prepreg 70. In this step, the prepreg 70 is cut to a specific size according to the product structure and unfolded drawing, and laid up on the tooling punch 30 according to the designed layup direction, sequence and area. Among them, the prepreg 70 in the outward flange area (referring to the area where the outward flange cavity 511 is located) is laid up on the outward flange fixing plate. The layup area includes the inner rib, transition area, thickened area, whole product skin and inner and outer flanges. The layup direction includes 0°, 90°, ±45° and 60°. The overall layup sequence is: inner rib layup → transition area and thickened area layup → whole product skin layup → inner and outer flange thickening and machining allowance layup.

[0057] The key control points for this step are designed as follows:

[0058] 1) During the layup process, fibers in the 0°, ±45°, and 60° directions need to be folded towards the end frame (please refer to...). Figure 2 The end frame part refers to the part corresponding to the inward flange and the outward flange, which respectively correspond to the part of the metal fixing plate 40 and the part of the punch 30 away from the axial end of the metal fixing plate 40, so as to achieve the continuity and integrity of the skin and the end frame part. After folding, the triangular area formed in the outward flange area is repaired with prepreg 70 of the corresponding size. The prepreg 70 overlapped in the inward flange area needs to be cut off to ensure the flatness of the inner and outer flange laying surface.

[0059] 2) The 90° plywood column segment and the inner and outer flange areas all adopt conformal plywood. The prepreg 70 in the inner and outer flange areas and the prepreg 70 of the column segment product skin are overlapped in the folding area.

[0060] 3) The prepreg 70 in the same layer is butted together with the gap controlled between 0 and 0.2 mm. During the layup process, it is necessary to ensure that the prepreg 70 is fully bonded and that there are no wrinkles or air bubbles. If wrinkles or air bubbles occur, manual intervention is required. The fibers must not be cut during the process.

[0061] 4) After the first layer is laid, vacuum pre-compression is required at room temperature. The vacuum pressure is -0.09 MPa to -0.1 MPa, and the time is controlled at 30 to 40 minutes to ensure that the prepreg 70 is tightly bonded to the tooling.

[0062] 5) During the layup process, vacuum pre-compression is performed every 4 to 8 layers at room temperature. The vacuum pressure is -0.09 MPa to -0.1 MPa, and the time is controlled at 15 to 30 minutes to remove the air brought into the interlayer by the layup.

[0063] 6) During the process of laying, heating and vacuum pre-pressing is carried out once every 2mm-3mm of laying, and it is particularly pointed out that the heating and vacuum pre-pressing process is carried out by using an oven and a vacuum pump instead of a hot press tank, which greatly reduces the use time and frequency of the hot press tank, reduces the use cost of the hot press tank, and effectively reduces the energy consumption cost; the heating and vacuum pre-pressing method using the oven is as follows: under the condition that the tooling is laid with the prepreg 70, the vacuum covering piece 60 is connected to the extension section 11 of the core cylinder 10, and the tooling in this state is placed in the oven, the oven is used as a heat source to provide heating conditions, and the vacuum pump is used to vacuum between the vacuum covering piece and the prepreg to form a pressurized condition and create a negative pressure environment; wherein the oven is used as a heat source, the pre-pressing temperature is determined according to the product forming resin system, and the pre-pressing temperature should not exceed the initial reaction temperature; the vacuum pump provides pressure by vacuumizing, and the pressure value is-0.095MPa to-0.1MPa.

[0064] 7) After pre-pressing, the missing material parts are repaired in time, and the high points are locally heated and pressed to ensure that the product surface is flat before each layer is laid.

[0065] After the above-mentioned laying and pre-pressing process is completed, the product vacuum packaging and curing step is carried out, and the hot press tank is used for heating and pressurizing curing under the condition that the concave die assembly and the vacuum covering piece are assembled. The control points of this step are designed as follows: when the product is vacuum packaged, the sealing boundary is set at the extension section 11 of the tooling core cylinder 10, and compared with the traditional vacuum whole packaging, the vacuum packaging form of this tooling can ensure that the hot flow of the hot press tank is transmitted to the product from both sides of the tooling, which effectively improves the heat transfer efficiency; the prepreg 70 is cured in the hot press tank, and the curing temperature system is determined according to the resin system, and the process adopts staged heating and holding form, the external pressure is controlled at 0.3-0.6MPa, and the vacuum pressure is-0.09MPa to-0.1MPa.

[0066] After the above-mentioned product vacuum packaging and curing step is completed, the demolding step is carried out, and the vacuum covering piece 60 and the auxiliary materials for realizing vacuum packaging, the metal cover plate 51, the first process skin 52, the second process skin 53 and the split convex die 30 need to be removed, and the intermediate product of the inner wide rib + inner and outer flange column section structure composite material cabin section is obtained, and the burrs of the intermediate product are polished and cleaned. The control points of this step are as follows: after the intermediate product is cured, it needs to be cooled to room temperature in the hot press tank before demolding to prevent product deformation; the burr polishing process cannot damage the fibers.

[0067] After the above-mentioned demolding step is completed, the detection and processing step is carried out, which needs to detect the internal quality and appearance of the intermediate product, needs to process the flange hole, needs to remove the processing allowance, and needs to ensure the flange flatness and overall height size.

[0068] The following provides a specific production process as a supplementary description of the above-mentioned inner and outer flange flange column segment structure composite cabin segment forming method:

[0069] 1) Produce a product with a process skin thickness of 4 mm, an inner and outer flange thickness of 8 mm, and a total shell height of 674 mm. The material is selected as T700 grade carbon fiber, the resin is a 230℃ cured bismaleimide resin, and the single layer theoretical thickness of the prepreg is 0.15 mm.

[0070] 2) According to the tooling instruction manual, disassemble, clean and assemble the tooling, and perform high-temperature release agent treatment on the tooling cavity parts and connecting screws for 2 times.

[0071] 3) Perform 70 prepreg layering and pre-pressing. The layering areas are transition zone, skin, and end frame, and the layering directions are 0°, 90°, ±45°, and 60°. According to the thickness of each part of the product and the thickness of the single layer prepreg 70, the layering number and overall layering sequence of each part are calculated as follows: 1 layer of bottom layering → 13 layers of inner wide rib, transition zone and thickening zone layering → 14 layers of transition zone and thickening zone layering → 27 layers of whole skin layering → outer flange thickening and processing allowance layering. After completing 4-8 layers of layering, perform pre-pressing at room temperature once, with a vacuum pressure of -0.09MPa to -0.1MPa and a time of 15min-30min; after completing 27 layers of layering, perform oven heating pre-pressing once, with a vacuum pressure of -0.095MPa to -0.1MPa, a temperature of 90℃-130℃, and a time of 0.5h-2h. After pre-pressing, fill the missing areas.

[0072] 4) Product vacuum packaging and curing. Specifically, install a metal cover plate 51, place a first process skin 52 and a second process skin 53 on the surface of the prepreg 70, use a certain thickness of steel strip as a baffle 54 to transition the gap between the process skin and the metal cover plate 51 and the gap between the process skins, use sealing tape and vacuum bag film as vacuum packaging pieces 60 to extend to the extension section 11 at both ends of the core cylinder 10; follow the established system to perform product curing, with a curing temperature of 230℃, a hot press tank pressure of 0.6MPa, and a vacuum pressure not greater than -0.09MPa.

[0073] 5) Demolding and polishing. Specifically, after the product curing is completed and the temperature decreases to room temperature, remove the process skin and the male die 30 to achieve demolding of the composite cabin segment, and use sandpaper to polish and clean the product corners.

[0074] 6) Detection and processing. Specifically, use ultrasonic C-scan and manual ultrasonic resonance methods to detect the internal quality of the product skin and front and rear end frames; use a caliper and a three-coordinate scanner to detect the product size; use visual methods to test the product appearance quality; use numerical control milling to process the product end face.

[0075] 7) Remove burrs from the machined surface and apply epoxy resin to the machined surface for protection.

[0076] In summary, in view of the problems of high cost, difficulty in forming and difficulty in guaranteeing internal quality of the composite material autoclave forming process of the wide rib + inside-out flange column segment structure in the field of aerospace, the present application provides a forming tool and an inside-out flange column segment structure composite material cabin forming method based on the tool, which takes into account product quality and forming efficiency. Through the combined tool structure design of the metal split convex die 30 + metal outside-out flange cover plate + process skin, and through the process scheme design using the tool, the problems of difficulty in forming and high internal quality risk of the product are overcome, the tool manufacturing cost is effectively reduced, the use time and length of the autoclave are shortened, the production efficiency is improved while the production cost is reduced; compared with the traditional metal concave-convex die tool structure using the autoclave for heating, vacuum pre-pressing, the tool provided by the present application uses an oven and a vacuum pump to replace the autoclave for pre-pressing, greatly reducing the use time and frequency of the autoclave, reducing the use cost of the autoclave, and improving the production efficiency; the product formed according to the disclosed scheme has the advantages of good appearance and internal quality, the production cycle is shortened by more than 40%, the forming cost is reduced by more than 30%, and significant economic benefits are achieved.

[0077] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications without departing from the spirit and scope of the application. Therefore, the appended claims are intended to cover all such changes and modifications that fall within the scope of the application.

[0078] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A forming tool, characterized by The forming tool for forming a composite cabin section of an inside-out flange column section structure comprises: a core cylinder; two support shafts oppositely arranged and connected to axial ends of the core cylinder; a male die connected to a cylinder surface of the core cylinder; a metal fixing plate connected to an outer peripheral surface of the male die; and a female die assembly comprising a metal cover plate, a first process skin and a second process skin, the metal cover plate is connected with the metal fixing plate and enclosed with the metal fixing plate to form an outside flange cavity, the metal cover plate can float in axial and radial directions of the core cylinder, the first process skin is used to enclose with an axial end of the male die away from the metal fixing plate to form an inside flange cavity, the second process skin is used to be arranged between the male die and enclosed with the male die to form a column section cavity, the outside flange cavity, the column section cavity and the inside flange cavity are sequentially communicated as a prepreg accommodating cavity.

2. The forming tool according to claim 1, wherein the metal cover plate, the first process skin and the second process skin are all annular split structure; the female die assembly further comprises a plurality of baffle plates, the baffle plates are arranged on at least one of an inner side of the first process skin, an inner side of the second process skin and a side of the metal cover plate facing the male die, and the baffle plates are respectively arranged in gaps between the first process skin and the second process skin, between the second process skin and the metal cover plate, between adjacent two split components of the first process skin and between adjacent two split components of the second process skin.

3. The forming tool according to claim 2, wherein the first process skin comprises: a cylinder portion spaced opposite to an outer peripheral surface of the male die, and the second process skin is located between the metal cover plate and the cylinder portion; and a ring portion connected with the cylinder portion, the ring portion is spaced opposite to an axial end of the male die away from the metal fixing plate, and the ring portion is enclosed with the male die to form the inside flange cavity.

4. The forming tool according to claim 1, wherein the male die is annular split structure, all split components of the male die are sequentially connected to the core cylinder at an outer periphery of the core cylinder, and the split components of the male die are connected with the core cylinder by pin positioning and screw connection.

5. The forming tool according to claim 4, wherein the male die is provided with a concave-convex surface at an outer periphery.

6. The forming tool according to any one of claims 1-5, wherein the core cylinder is provided with extension sections axially extending beyond a distribution area of the male die, and the extension sections are oppositely arranged at axial two sides of the male die; the forming tool further comprises a vacuum cladding member, the vacuum cladding member is used to be sleeved on the male die, the metal fixing plate and the female die assembly, and two ends of the vacuum cladding member are respectively detachably connected to the two extension sections; the support shaft is provided with a gas hole, and the support shaft is provided with a gas channel connecting the gas hole and a cylinder cavity of the core cylinder.

7. A method for molding composite material compartment sections with inward and outward folding flange column sections, characterized in that, The forming tool as claimed in claim 6, the inner and outer flange column segment structure composite cabin segment forming method comprises: Prepreg laying is performed on the male die and the metal fixing plate, and pre-pressing is performed during the prepreg laying; After the prepreg laying is completed, heating and pressurizing curing is performed by a hot press tank under the condition that the female die assembly and the vacuum bag are assembled; After the heating and pressurizing curing is completed, demolding is performed to obtain the inner and outer flange column segment structure composite cabin segment.

8. The inner and outer flange column segment structure composite cabin segment forming method as claimed in claim 7, wherein During the prepreg laying, the pre-pressing comprises first normal-temperature vacuumizing and pre-pressing after first layer laying, intermittent normal-temperature vacuumizing and pre-pressing every 4-8 layers of prepreg laying, and heating vacuumizing and pre-pressing every 2-3 mm thickness of prepreg laying, and the pre-pressing is performed under the condition that the female die assembly and the vacuum bag are assembled.

9. The inner and outer flange column segment structure composite cabin segment forming method as claimed in claim 8, wherein During the heating vacuumizing and pre-pressing, the forming tool on which the prepreg is laid and on which the female die assembly is not installed is placed in an oven, the oven is used as a heat source to form a heating condition, and a vacuum pump is used to vacuumize and pressurize between the vacuum bag and the prepreg.

10. The inner and outer flange column segment structure composite cabin segment forming method as claimed in claim 7, wherein During the demolding, post-processing is further performed on the intermediate product obtained after the demolding, the post-processing comprises polishing, detecting, and reprocessing the intermediate product, and the intermediate product after the polishing is detected and processed again, and the detecting comprises internal quality detection and appearance detection.

Images