Forming tool and method for forming composite cabin section of internally and externally turned flange column section structure

Abstract

The invention discloses a forming tool and an inward and outward turning flange column section structure composite material cabin section forming method.The forming tool comprises a core barrel, supporting shafts, a male die, a metal fixing plate and a female die assembly, the two supporting shafts are connected to the two axial ends of the core barrel correspondingly, the male die is connected to the barrel face of the core barrel in a surrounding mode, and the metal fixing plate is connected to the peripheral face of the male die in a surrounding mode; 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, the metal cover plate and the metal fixing plate define an outward-turning flange cavity, and the metal cover plate can float in the axial direction and the radial direction of the core cylinder. The first process skin and the axial end, away from the metal fixing plate, of the male die are enclosed to form an inwards-turned flange cavity, the second process skin is wound around the male die and is enclosed with the male die to form a column section cavity, and the outwards-turned flange cavity, the column section cavity and the inwards-turned flange cavity are sequentially communicated. The internal quality risk of the product is reduced, the manufacturing cost and the heat sink of the female die can be effectively reduced, and the heat transfer efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material molding, and in particular to a molding tool and a method for molding a composite material cabin section of an inside-out flange column structure. Background Art

[0002] Carbon fiber reinforced resin-based composite materials have become the main load-bearing structural materials in the aerospace field. With the development of science and technology, their structures have gradually developed from simple to complex. The vast majority of carbon fiber cabin products are formed by autoclave molding.

[0003] In the field of aerospace, composite cabin sections require high-quality internal and external dimensions. For example, for an inside-out flange column section structure with an outside flange on one side and an inside flange on the other side, in order to facilitate paving and forming, a forming method is adopted in which the preform is paved on a convex mold and pre-pressed into a preform, and finally a metal concave mold is installed for dimensional curing. However, the tooling form in this forming method is difficult to ensure a close fit between the preform and the metal concave mold, and the inside-out flange column section structure produced by this method has certain internal quality risks. Summary of the invention

[0004] In order to solve the above problems, the present application provides a molding tool and a molding method for a composite cabin section of an inside-out flange column structure.

[0005] The present application provides a molding tool for molding a composite cabin section of an inside-out flange column structure. The molding tool includes a core barrel, a support shaft, a punch, a metal fixing plate and a die assembly. Two support shafts are relatively arranged, and the two support shafts are respectively connected to the axial ends of the core barrel. The punch is connected to the barrel surface of the core barrel, and the metal fixing plate is connected to the outer peripheral surface of the punch. The die assembly includes a metal cover plate, a first process skin and a second process skin. The metal cover plate is connected to the metal fixing plate and enclosed with the metal fixing plate to form an outward-turned flange cavity. The metal cover plate can float along the axial and radial directions of the core barrel. The first process skin is used to enclose with the axial end of the punch away from the metal fixing plate to form an inward-turned flange cavity. The second process skin is used to be wrapped around the punch and enclosed with the punch to form a column section cavity. The outward-turned flange cavity, the column section cavity and the inward-turned flange cavity are connected in sequence to form a prepreg accommodating cavity.

[0006] In some embodiments, the metal cover plate, the first process skin and the second process skin are all annular petal structures, and the die assembly also includes a plurality of baffles, which are laid on the inner side of the first process skin, the inner side of the second process skin and at least one of the sides of the metal cover plate facing the punch, and 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 two adjacent petal components of the first process skin and the gap between two adjacent petal components of the second process skin.

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

[0008] The barrel portion is spaced and directly opposite to the outer peripheral surface of the punch, and the second process skin is located between the metal cover plate and the barrel portion; and

[0009] The ring part is connected with the cylinder part, and is spaced and aligned with an axial end of the punch away from the metal fixing plate. The ring part and the punch are enclosed to form an inverted flange cavity.

[0010] In some embodiments, the punch is an annular petal structure, and all petal components of the punch are sequentially connected to the outer periphery of the core tube along the annular direction of the core tube. The petal components of the punch and the core tube are connected by pin positioning and matching screws.

[0011] In some embodiments, the male mold has a concave-convex surface on the outer periphery.

[0012] In some embodiments, the core barrel is provided with an extension section that exceeds the distribution area of ​​the punch in the axial direction, and two extension sections are provided opposite to each other, and the two extension sections are respectively located on both sides of the axial direction of the punch;

[0013] The molding tool also includes a vacuum coating member, which is used to be sleeved outside the male mold, the metal fixing plate and the female mold assembly, and the two ends of the vacuum coating member are detachably connected to the two extension sections respectively;

[0014] The support shaft is provided with an air hole, and an air passage connecting the air hole and the barrel cavity of the core barrel is arranged in the support shaft.

[0015] A method for forming a composite cabin section with an inside-out flange column structure, using the above-mentioned forming tooling, the method for forming a composite cabin section with an inside-out flange column structure comprises:

[0016] Prepreg is laid on the punch and the metal fixing plate, and pre-pressed during the prepreg laying process;

[0017] After the prepreg layering is completed, the concave mold assembly and the vacuum coating are assembled and heated and pressurized in an autoclave for curing;

[0018] After the heating and pressurizing curing is completed, demoulding is carried out to obtain the composite cabin section with inside-out flange column structure.

[0019] In some embodiments, during the prepreg laying process, prepressing includes the first room temperature vacuum prepressing after the first layer is laid, intermittent room temperature vacuum prepressing for every 4-8 layers of prepreg laid, and heated vacuum prepressing for every 2mm-3mm thick prepreg laid. The prepressing is performed by vacuuming and pressurizing under the condition of assembling the cavity mold assembly and the vacuum bag accessories.

[0020] In some embodiments, during the heating and vacuum pre-pressing process, the molding tooling with the prepreg-covered but unmounted die assembly and vacuum-coated part is placed in an oven, the oven is used as a heat source to form heating conditions, and a vacuum pump is used to evacuate the space between the vacuum-coated part and the prepreg to form pressurized conditions.

[0021] In some embodiments, the demolding process also includes post-processing the intermediate product obtained after demolding, and the post-processing includes polishing, testing and reprocessing the intermediate product, and further testing and processing the polished intermediate product, and the testing includes internal quality testing and appearance testing.

[0022] The beneficial effects of the present application are as follows: a molding tool is provided, which is specially used for molding composite cabin sections of inverted flange column structures. Two support shafts are connected to the axial ends of the core barrel, and the core barrel can be rotated through the support shafts. The punch is connected to the barrel surface of the core barrel, and the metal fixing plate is connected to the outer peripheral surface of the punch. The die assembly is specially designed. The die assembly includes a metal cover plate, a first process skin, and a second process skin. The metal cover plate is connected to the metal fixing plate and enclosed with the metal fixing plate to form an inverted flange cavity. The metal cover plate can be rotated along the core barrel. The cylinder is axially and radially floating, the first process skin is used to enclose the axial end of the punch away from the metal fixing plate to form an inverted flange cavity, the second process skin is used to be wound around the punch and enclosed by the punch to form a column cavity, the outward flange cavity, the column cavity and the inverted flange cavity are sequentially connected to form a prepreg accommodating cavity; in the tooling technology for forming the composite cabin section of the inverted flange column structure, the present application scheme replaces the traditional metal die with a die assembly including a metal cover plate, a first process skin and a second process skin, and uses a metal cover plate and a metal fixing plate to form a prepreg cavity. The plates are clamped to form an outward-turned flange cavity, the first process skin and the punch are used to enclose the inward-turned flange cavity, and the second process skin and the punch are used to enclose the column segment cavity. During the vacuum curing of the prepreg in the autoclave, the metal cover plate, the first process skin and the second process skin can be slightly moved with the prepreg, which can ensure that the prepreg and the various components in the die assembly are always tightly fitted, thereby reducing the internal quality risk of the product caused by the separation of the prepreg and the metal die in the traditional metal die method, overcoming the problem that the product is difficult to form due to the separation of the prepreg and the metal die in the traditional metal die method, and the contour of the product is guaranteed by the die assembly in the tooling, so that the product has a good appearance; on the other hand, compared with the traditional metal die scheme, the present application scheme adopts a die assembly including a metal cover plate, a first process skin and a second process skin, which can effectively reduce the manufacturing cost of the die, effectively reduce the heat sink of the die, improve the heat transfer efficiency, and reduce the energy consumption cost during molding production, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0024] Figure 1 A schematic diagram of the structure of a molding tool provided in the present application when a concave mold assembly is not installed;

[0025] Figure 2 A schematic cross-sectional view of a molding tool provided in the present application when a concave mold assembly is not installed;

[0026] Figure 3 A schematic diagram of the concave and convex surface of a punch in a molding tool provided in the present application;

[0027] Figure 4 A schematic diagram of a prepreg between a male mold and a female mold assembly in a molding tool provided in the present application;

[0028] Figure 5 A schematic diagram of an outward-turned flange cavity, a column segment cavity and an inward-turned flange cavity in a molding tool provided in the present application;

[0029] Figure 6 A schematic diagram of the arrangement of a baffle in a molding tool provided in the present application;

[0030] Figure 7 A schematic diagram of another arrangement of a baffle in a molding tool provided in the present application;

[0031] Figure 8 A schematic diagram of the main process of a method for forming a composite cabin section with an inside-out flange column structure provided in this application.

[0032] The accompanying drawings are marked with: 10-core tube, 11-extension section, 20-support shaft, 21-air hole, 30-punch, 31-concave and convex surface, 40-metal fixing plate, 401-first waist-shaped hole, 51-metal cover plate, 511-outward-turned flange cavity, 512-second waist-shaped hole, 52-first process skin, 521-inward-turned flange cavity, 522-cylinder part, 523-ring part, 53-second process skin, 531-column section cavity, 54-baffle, 60-vacuum covering part, 70-preg material. DETAILED DESCRIPTION

[0033] The present invention discloses a molding tool, hereinafter referred to as the tool, which is used for molding a composite cabin section of an inside-out flange column section structure, especially through autoclave molding. The inside-out flange column section structure includes a cylindrical structure as a main structure, an inside-out flange connected to one axial end of the cylindrical structure, and an outside-out flange connected to the other axial end of the cylindrical structure. The structure is made of composite materials through an autoclave molding method. In particular, the tool of the present invention is used for molding carbon fiber reinforced resin-based composite materials, and the molded products belong to the main load-bearing structures in the aerospace field.

[0034] Please refer to Figure 1 and Figure 2 The tooling includes a core barrel 10 and a support shaft 20, a punch 30 and a metal fixing plate 40. The core barrel 10 serves as the installation base of the punch 30. The core barrel 10 is designed to be a cylindrical structure, and the barrel cavity of the core barrel 10 is large enough to achieve a sufficient weight reduction effect. In order to realize the rotatable function of the core barrel 10, a support shaft 20 is connected to each of the axial ends of the core barrel 10. The support shaft 20 and the core barrel 10 can be connected by screws. The support shaft 20 plays a supporting role and assists the rotation of the core barrel 10, which is convenient for the laying operation when the punch 30 lays the prepreg 70.

[0035] Please refer to Figure 1 and Figure 2 The tooling includes a punch 30, which is connected to the surface of the core tube 10 in a surrounding manner. The surrounding connection means that the punch 30 is both installed on the surface of the core tube 10 and surrounds the surface of the core tube 10. Generally speaking, the punch 30 is an annular petal structure, and multiple petal structures are assembled together to form the punch 30. Please refer to Figure 1 and Figure 2 All petal components of the punch 30 are distributed along the circumference of the core barrel 10, and each petal component of the punch 30 is connected to the outer periphery of the core barrel 10. In some embodiments, the petal components of the punch 30 and the core barrel 10 are connected by pin positioning and matching screws, which can ensure the installation accuracy of the punch 30 on the core barrel 10.

[0036] Please refer to Figure 1 and Figure 2 The tooling includes a metal fixing plate 40, which is connected to the outer peripheral surface of the punch 30. The metal fixing plate 40 not only surrounds the outer peripheral surface of the punch 30, but is also connected to the outer peripheral surface of the punch 30. The metal fixing plate 40 and the petal components of the punch 30 can be connected by screws. The function of the metal fixing plate 40 is to provide a reference for the laying of the outward-turned flange.

[0037] When the tooling is used, the prepreg 70 needs to be laid on the male mold 30 and the metal fixing plate 40 and pre-pressed, and then vacuum-cured in an autoclave after the female mold is assembled. Figure 5 I just want to express the ply position of prepreg 70. Figure 5 This does not belong to the use status of this tooling. Figure 4 and Figure 5 It is helpful to understand the groove components in this tooling.

[0038] Please refer to Figure 2 , Figure 4 and Figure 5 The tooling includes a die assembly, and 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 to the metal fixing plate 40, and 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-turned flange cavity 511. After the molding is completed, the prepreg 70 in the outward-turned flange cavity 511 will form an outward-turned flange of the composite cabin section of the inner-outward-turned flange column section structure. The prepreg 70 is layered on the axial end of the punch 30 away from the metal fixing plate 40, and 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-turned flange cavity 521. After the molding is completed, the prepreg 70 in the inward-turned flange cavity 521 will form an inward-turned flange of the composite cabin section of the inner-outward-turned flange column section structure. 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 FIG. Figure 5 As shown, the outward-turned flange cavity 511 , the column segment cavity 531 and the inward-turned flange cavity 521 are sequentially connected to form a cavity for accommodating the prepreg 70 .

[0039] In this tooling, the connection method 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 tube 10 and the radial floating along the core tube 10, so that the metal cover plate 51 can always be in contact with the prepreg 70 during the vacuum curing process, ensuring effective pressure on the prepreg 70. There are many different implementation methods of floating connection in the prior art. In this application, a solution for realizing floating connection through waist-shaped holes is provided. Please refer to Figure 1 and Figure 2, a plurality of first waist-shaped holes 401 are provided on the metal fixing plate 40, and the length direction of the first waist-shaped holes 401 is the same as the radial direction of the core tube 10, and a first screw is installed in the first waist-shaped hole 401, and the first screw is threadedly connected to the metal cover plate 51, and 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 tube 10; similarly, a second waist-shaped hole 512 is provided on the metal cover plate 51, and the length direction of the second waist-shaped hole 512 is the same as the axial direction of the core tube 10, and a second screw is installed in the second waist-shaped hole 512, and the second screw is threadedly connected to the metal fixing plate 40, and 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 tube 10; please refer to Figure 1 The metal cover plate 51 is designed as an annular petal structure, and the multiple petal components belonging to the metal cover plate 51 are distributed in sequence along the annular direction of the punch 30, and each petal component belonging to the metal cover plate 51 is connected to the metal fixing plate 40 respectively.

[0040] In the tooling technology for forming the composite cabin section of the inside-out flange column structure, the technical solution of the tooling replaces the traditional metal die with a die assembly including a metal cover plate 51, a first process skin 52, and a second process skin 53. The metal cover plate 51 and the metal fixing plate 40 are clamped to form an outside-out flange cavity 511, the first process skin 52 and the punch 30 are enclosed to form an inside-out flange cavity 521, and the second process skin 53 and the punch 30 are enclosed to form a column cavity 531. During 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 be slightly moved along with the prepreg 70, which can ensure that the prepreg 70 is always in close fit with the various components in the die assembly, thereby reducing the internal quality risk of the product caused by the separation of the prepreg 70 from the metal die in the traditional metal die method, overcoming the problem that the product is difficult to form due to the separation of the prepreg 70 from the metal die in the traditional metal die method, and the contour of the product is guaranteed by the die assembly in the tooling, so that the product has a good appearance.

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

[0042] In some embodiments, the first process skin 52 is an annular petal structure, and there is a gap between two adjacent petal components of the first process skin 52 in the annular direction, thereby ensuring that the first process skin 52 and the prepreg 70 are always tightly fitted during the vacuum curing process; similarly, the second process skin 53 is an annular petal structure, and there is a gap between two adjacent petal components of the second process skin 53 in the annular direction, thereby ensuring that the second process skin 53 and the prepreg 70 are always tightly fitted during the vacuum curing process.

[0043] For the gap between two adjacent petal components in the circumferential direction, the die assembly includes a plurality of baffles 54, which are used to cover the gap. Corresponding to the gap between two adjacent petal components in the circumferential direction of the first process skin 52, the baffles 54 are laid on the inner side of the first process skin 52. 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. Figure 7 (Although Figure 7 The second process skin 53 is marked in the figure, but it can also be understood as a reference figure), and the baffle 54 is arranged across the gap between two adjacent petal components of the first process skin 52.

[0044] Similarly, corresponding to the gap between two adjacent petal components in the annular direction of the second process skin 53, the die assembly includes a plurality of baffles 54, which are laid on the inner side of the second process skin 53. 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 as Figure 7 The baffle 54 is arranged across the gap between two adjacent petal components of the second process skin 53 .

[0045] Please refer to Figure 4 and Figure 5 , the first process skin 52 is spaced from the second process skin 53, the die assembly includes a baffle 54, please refer to Figure 6 The baffle 54 is laid on the inner side of the first process skin 52 and the inner side of the second process skin 53 , and the baffle 54 spans 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 is spaced apart from the metal cover plate 51, and the die assembly includes a baffle 54, which is 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 baffle 54 spans the gap between the second process skin 53 and the metal cover plate 51.

[0047] In the tooling of the present application, the baffle 54 has a certain rigidity and a certain deformation ability, which can not only ensure the contour of the product, but also meet the purpose of bonding with the prepreg 70. During the vacuum curing process, the baffle 54 and the process skin are deformed. Therefore, in the actual production process, it is necessary to consider the material and specifications of the baffle 54. For example, a steel strip with a thickness of 0.1mm is used as the baffle 54, and the thickness of the baffle 54 is controlled to be extremely small at 0.1mm-0.2mm. This solution has been verified in actual production.

[0048] When installing the first process skin 52, the second process skin 53 and multiple baffles 54, auxiliary means can be used to simplify the installation process. For example, tape can be used to simultaneously bond all the circumferentially distributed petal components of the first process skin 52 and the baffles in the gaps between two adjacent petal components. Then, the first process skin 52, the corresponding baffles and the tape are placed together outside the prepreg.

[0049] Regarding the process skin, it can be made of different materials such as fiberglass, carbon fiber composite materials, etc., which have been verified in actual production.

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

[0051] The above fully explains the use of this tooling for the molding of composite cabin sections with inside-out flange column sections. In the technical scope of composite cabin sections in the aerospace field, there is an inner wide rib + inside-out flange column section structure. This tooling can be further used for the molding of composite cabin sections with inner wide rib + inside-out flange column section structure. Please refer to Figure 1 and Figure 3 The convex mold 30 is provided with a concave-convex surface 31 on the outer periphery. The prepreg 70 is laid on the convex mold 30 and then vacuum cured. The concave-convex surface 31 can be used to make the produced composite material cabin section have internal wide ribs. The concave-convex surface 31 must be designed according to the actual product shape.

[0052] In some embodiments, see Figure 1 and Figure 2 The core barrel 10 is provided with an extension section 11 which exceeds the distribution area of ​​the punch 30 in the axial direction. Two extension sections 11 are relatively provided. The two extension sections 11 are respectively located on both sides of the axial direction of the punch 30. The molding tool also includes a vacuum coating 60. The vacuum coating 60 is generally a vacuum bag film. The two ends of the vacuum coating 60 are respectively detachably connected to the two extension sections 11, and the vacuum coating 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 an air passage that conducts the air hole 21 and the barrel cavity of the core barrel 10. The hot air can enter the core barrel 10 through the air hole 21.

[0053] In the step of laying the prepreg 70 on the male mold 30, the prepreg 70 needs to be pre-pressed, and the pre-pressing operation is achieved by heating and vacuuming. Compared with the traditional solution of vacuum bag coating the entire tooling, the solution of the extension section 11, vacuum coating member 60 and air hole 21 adopted in this application can make the heat flow enter the core tube 10 from the air hole 21, thereby realizing the heat flow from the inside and outside of the tooling to the prepreg 70. The heat transfer efficiency is effectively improved.

[0054] The present invention also provides a method for forming a composite cabin section with an inside-out flange column section structure. By using the above-mentioned forming tooling, a composite cabin section with an inside-out flange column section structure can be produced. When the outer periphery of the punch 30 is designed with a concave-convex surface 31, a composite cabin section with inner wide ribs + inside-out flange column section structure can also be produced. Figure 8 The basic steps of the method are shown, in which the overall layering and process pre-pressing steps of the prepreg 70, the vacuum curing step of the product package, the demoulding step, and the testing and processing steps are carried out in sequence. In the overall layering and process pre-pressing step of the prepreg 70, the prepreg 70 is layered on the tooling, specifically, the prepreg 70 is layered on the punch and the metal fixing plate, and pre-pressed during the layering process. In the vacuum curing step of the product package, the die assembly and the vacuum coating 60 are first assembled, and then heated and pressurized by the autoclave for curing. In the demoulding step, demoulding is carried out and the intermediate product is obtained. In the testing and processing step, the product is inspected for internal quality and appearance, and the intermediate product is processed, including but not limited to the processing of the flange holes of the inverted flange and the outverted flange, to ensure the flange flatness and the overall height size, and obtain the inverted and outverted flange column section structure composite material cabin section 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 demoulding can proceed smoothly.

[0056] The following is a further design of the overall layup and process pre-pressing steps of the prepreg 70. In this step, the prepreg 70 is cut into specific sizes according to the product structure and the unfolded diagram, and is laid on the tooling punch 30 according to the designed layup direction, sequence and area, wherein (the outward-turned flange area refers to the area where the outward-turned flange cavity 511 is located) the prepreg 70 in the outward-turned flange area is laid on the outward-turned flange fixing plate, and the layup area includes inner width ribs, transition areas, thickened areas, the entire product skin and inner and outer turned flanges, and the layup directions include 0°, 90°, ±45°, and 60°; the overall layup sequence is inner width rib layup → transition area, thickened area layup → entire product skin layup → inner and outer turned flange thickening and processing allowance layup.

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

[0058] 1) During the laying process, the fibers in the 0°, ±45° and 60° directions need to be folded toward the end frame (see Figure 2 The end frame part refers to the part corresponding to the inward-turned flange and the outward-turned flange, which respectively correspond to the part of the metal fixing plate 40 and the part of the axial end of the punch 30 away from the metal fixing plate 40) to achieve the continuity and integrity of the skin and the end frame part. The triangular area formed in the outward-turned flange area after folding is repaired with prepreg 70 of corresponding size. The overlapping prepreg 70 in the inward-turned flange area needs to be cut and removed to ensure the flatness of the inner and outer flange paving surfaces.

[0059] 2) The 90° laminated column section and the inner and outer flange areas all adopt conformal laminated layers, and the prepreg 70 of the inner and outer flange areas and the prepreg 70 of the column section product skin are overlapped in the folded area.

[0060] 3) The two adjacent prepregs 70 in the same layer are butt-jointed, with the gap controlled at 0-0.2 mm. During the lamination process, the prepregs 70 must be fully fitted together without wrinkles or hollows. If wrinkles or hollows occur, manual intervention is required, and the fibers must not be cut during the process.

[0061] 4) After the first layer is laid, vacuum pre-pressing is required at room temperature, with a vacuum pressure of -0.09Mpa to -0.1MPa, and the time is controlled within 30 to 40 minutes to ensure that the prepreg 70 is closely fitted to the tooling.

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

[0063] 6) During the layering process, heating and vacuum pre-pressing are performed once every 2mm to 3mm of each layer. It should be noted that the heating and vacuum pre-pressing process uses an oven and a vacuum pump instead of an autoclave for heating and vacuum pre-pressing, which greatly reduces the use time and number of autoclaves, reduces the use cost of the autoclave, and effectively reduces the energy consumption cost; the method of using an oven for heating and vacuum pre-pressing is specifically as follows: under the condition that the tooling is paved with prepreg 70, the vacuum coating part 60 is connected to the extension section 11 of the core tube 10, and the tooling in this state is placed in the oven, and the oven is used as a heat source to provide heating conditions, and a vacuum pump is used to evacuate the space between the vacuum coating part and the prepreg to form a pressurized condition, thereby creating a negative pressure environment; wherein the oven is used as a heat source, and the pre-pressing temperature is determined according to the product molding resin system, and the pre-pressing temperature shall not exceed the starting reaction temperature; the vacuum pump evacuates to provide pressure, and the pressure value is -0.095Mpa to -0.1MPa.

[0064] 7) After pre-pressing, repair the missing parts in time and perform local heating and pressing treatment on the high points to ensure that the product surface is flat before each layer is laid.

[0065] After the above-mentioned layering and process pre-pressing are completed, the product package vacuum curing step is carried out, and the die assembly and vacuum coating parts are assembled and heated and pressurized by the autoclave for curing. The control points of this step are designed as follows: When the product is vacuum coated, the sealing boundary is set at the extension section 11 of the tooling core barrel 10. Compared with the traditional vacuum overall coating, the vacuum packaging form of the tooling can ensure that the heat flow of the autoclave transfers heat to the product from both sides of the tooling, effectively improving the heat transfer efficiency; the prepreg 70 is cured in the autoclave, and the curing temperature system is determined according to the resin system. The process adopts the form of stage heating and heat preservation, and the external pressure is controlled at 0.3~0.6MPa, and the vacuum pressure is -0.09MPa~-0.1MPa.

[0066] After completing the vacuum curing step of the above-mentioned product package, the demoulding step is carried out, and the vacuum coating part 60 and the auxiliary materials for vacuum coating, the metal cover plate 51, the first process skin 52, the second process skin 53 and the splitting punch 30 need to be removed, and the intermediate product of the composite cabin section of the inner wide rib + inner and outer flange column structure is obtained, and the burrs of the intermediate product are polished and cleaned. The control points of this step are: after the intermediate product is cured, it needs to be cooled to room temperature in the autoclave with the furnace before demoulding to prevent product deformation; the fiber must not be damaged during the burr polishing process.

[0067] After completing the above demoulding steps, the inspection and processing steps are carried out. The internal quality and appearance of the intermediate product need to be inspected, the flange hole needs to be processed, and the processing allowance needs to be removed to ensure the flange flatness and overall height size.

[0068] The following provides a specific production process as a supplementary explanation of the above-mentioned method for forming the composite cabin section of the inside-out flange column structure:

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

[0070] 2) Disassemble, clean and assemble the tooling according to the tooling instruction manual, and treat all parts of the tooling cavity and connecting screws with high-temperature release agent twice.

[0071] 3) Perform prepreg 70 layer laying and prepressing. The layering areas are transition zone, skin, and end frame. The layering directions are 0°, 90°, ±45°, and 60°. According to the thickness of each part of the product and the thickness of a single layer of prepreg 70, the number of layers of each part and the overall layering sequence are calculated as follows: 1 layer of base layer → 13 layers of inner wide reinforcement, transition zone and thickening zone layers → 14 layers of transition zone and thickening zone layers → 27 layers of whole skin layers → outer flange thickening and processing allowance layers. Among them, a normal temperature prepressing is performed after every 4 to 8 layers of laying, the vacuum pressure is -0.09MPa to -0.1MPa, and the time is 15min-30min; after every 27 layers of laying, an oven heating prepressing is performed, the vacuum pressure is -0.095MPa to -0.1MPa, the temperature is 90℃ to 130℃, and the time is 0.5h to 2h. After the prepressing is completed, the missing material area is repaired with fillers.

[0072] 4) Carry out vacuum packing and curing of the product, specifically, it is necessary to 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 steel belt of a certain thickness as a baffle 54 for transition in the gap between the process skin and the metal cover plate 51 and the gap between the process skins, use sealing strips and vacuum bag films as vacuum coating parts 60, and vacuum coat the extension sections 11 at both ends of the core tube 10; cure the product according to the established system, the curing temperature is 230°C, the autoclave pressure is 0.6MPa, and the vacuum pressure is not greater than -0.09MPa.

[0073] 5) Demolding and polishing are performed. Specifically, after the product is cured and the temperature is reduced to room temperature, the process skin and the punch 30 are removed to demould the composite cabin section, and sandpaper is used to polish and clean the glue at the corners of the product.

[0074] 6) Carry out inspection and processing, specifically use ultrasonic C-scan and manual ultrasonic resonance methods to inspect the product skin and the internal quality of the front and rear end frames; use calipers and three-coordinate scanning to inspect the product's external dimensions; use visual methods to inspect the product's appearance quality; use CNC milling to process the product end face.

[0075] 7) Remove burrs from the machined surface and protect it with epoxy resin.

[0076] In summary, in view of the high cost of hot-pressed molding process of composite materials of wide ribs + inside-out flange column section structure in the aerospace field, the difficulty of product molding, and the difficulty in ensuring internal quality, the present invention provides a molding tool and a molding method of composite cabin section of inside-out flange column section structure based on the tool, which takes into account both product quality and molding efficiency, and overcomes the problems of difficult molding of the above-mentioned products and high internal quality risks through the combined tooling structure design of metal split-flange punch 30 + metal outside-out flange cover plate + process skin, and the process scheme design using the tooling, while effectively reducing the tooling manufacturing cost. The invention not only reduces the cost, but also shortens the number of times and duration of using the autoclave, thereby improving product production efficiency while reducing production costs. Compared with the traditional metal concave and convex mold tooling structure that uses the autoclave for heating and vacuum pre-pressing, the tooling provided by the invention uses an oven and a vacuum pump instead of the autoclave for pre-pressing, which greatly reduces the duration and number of times the autoclave is used, reduces the cost of using the autoclave, and improves production efficiency. The products formed according to the scheme disclosed in the invention have the advantages of good appearance and internal quality, the production cycle is shortened by more than 40%, the molding cost is reduced by more than 30%, and has significant economic benefits.

[0077] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

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

Claims

1. A molding tool, characterized in that: Used for forming composite cabin sections of flange column sections with inward and outward turning, the forming tooling includes: Core barrel; Two supporting shafts are provided opposite to each other, and the two supporting shafts are respectively connected to the axial ends of the core barrel; A male mold, surrounding and connected to the cylinder surface of the core cylinder; A metal fixing plate, surroundingly connected to the outer peripheral surface of the male mold; and A die assembly comprises a metal cover plate, a first process skin and a second process skin, wherein the metal cover plate is connected to the metal fixing plate and encloses the metal fixing plate to form an outward-turned flange cavity, the metal cover plate can float along the axial and radial directions of the core tube, the first process skin is used to enclose an axial end of the punch away from the metal fixing plate to form an inward-turned flange cavity, the second process skin is used to be arranged between the punch and enclose the punch to form a column segment cavity, the outward-turned flange cavity, the column segment cavity and the inward-turned flange cavity are connected in sequence to form a prepreg accommodating cavity.

2. The molding tool according to claim 1, characterized in that: The metal cover plate, the first process skin and the second process skin are all annular petal structures; The die assembly also includes a plurality of baffles, which 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 punch 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 two adjacent petal components of the first process skin, and the gap between two adjacent petal components of the second process skin.

3. The molding tool according to claim 2, characterized in that: The first process skin includes: The barrel portion is spaced apart and directly opposite to the outer peripheral surface of the punch, and the second process skin is located between the metal cover plate and the barrel portion; and The ring portion is connected to the cylinder portion, and the ring portion is spaced apart and directly opposite to an axial end of the punch away from the metal fixing plate. The ring portion and the punch are enclosed to form the inverted flange cavity.

4. The molding tool according to claim 1, characterized in that: The punch is an annular petal structure, and all the petal components of the punch are sequentially connected to the outer periphery of the core tube along the annular direction of the core tube. The petal components of the punch and the core tube are connected by pin positioning and matching screws.

5. The molding tool according to claim 4, characterized in that: The convex mold is provided with a concave-convex surface on the outer periphery.

6. The molding tool according to any one of claims 1 to 5, characterized in that: The core barrel is provided with an extension section which exceeds the distribution area of ​​the punch in the axial direction, and two extension sections are provided opposite to each other, and the two extension sections are respectively located on both sides of the axial direction of the punch; The molding tool further includes a vacuum covering member, which is used to be sleeved outside the male mold, the metal fixing plate and the female mold assembly, and the two ends of the vacuum covering member are detachably connected to the two extension sections respectively; The support shaft is provided with an air hole, and an air passage connecting the air hole and the barrel cavity of the core barrel is provided in the support shaft.

7. A method for forming a composite cabin section with an inside-out flange column structure, characterized in that: Using the molding tool as claimed in claim 6, the method for molding a composite cabin section of an inside-out flange column structure comprises: Laying prepreg on the male mold and the metal fixing plate, and performing pre-pressing during the prepreg laying process; After the prepreg layering is completed, heating and pressurizing and curing are performed in an autoclave under the condition of assembling the concave mold assembly and the vacuum coating component; After the heating and pressurizing curing is completed, demoulding is performed to obtain the composite cabin section with the inside-out flange column structure.

8. The method for forming a composite cabin section of an inside-out flange column structure according to claim 7, characterized in that: During the prepreg laying process, the prepressing includes the first vacuum prepressing at room temperature after the first layer is laid, the intermittent vacuum prepressing at room temperature for every 4-8 layers of prepreg laid, and the heated vacuum prepressing for every 2mm-3mm thick prepreg laid. The prepressing is performed by vacuuming and pressurizing under the condition of assembling the die assembly and the vacuum bag accessories.

9. The method for forming a composite cabin section of an inside-out flange column structure according to claim 8, characterized in that: During the heating vacuum pre-pressing process, the molding tooling covered with prepreg but not equipped with the concave mold assembly is placed in the oven, the oven is used as a heat source to form a heating condition, and a vacuum pump is used to evacuate the space between the vacuum coating part and the prepreg to form a pressurized condition.

10. The method for forming a composite cabin section of an inside-out flange column structure according to claim 7, characterized in that: The demoulding process also includes post-processing of the intermediate product obtained after demoulding, and the post-processing includes grinding, testing and reprocessing of the intermediate product, and further testing and processing of the intermediate product after grinding, and the testing includes internal quality testing and appearance testing.

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