A forming method of an aero-engine resin matrix composite outer-duct integral case
By employing a horizontal rotary molding die and a segmented pressure curing strategy, the problems of low efficiency, poor quality consistency, and significant deformation in the manufacturing of resin-based composite outer casings for aero-engines were solved, achieving an efficient and stable manufacturing process.
Patent Information
- Application Number
- CN202611469894.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-21
- Publication Date
- 2026-11-06
AI Technical Summary
Existing technologies for manufacturing resin-based composite outer casings for aero-engines suffer from several problems, including low efficiency and poor quality consistency due to the limited manual application posture; wrinkles and defects caused by uneven material accumulation or bridging in complex R-corner areas; and large residual stress and significant deformation due to mismatched temperature-pressure curves during the curing process.
A horizontal rotary molding die is used to cut the prepreg into narrow strips and apply twisting around its length to form flexible filler strips. These strips are then filled and compacted layer by layer in a pyramid shape in the R-corner area. Combined with the rotation of the die, prepreg sheets are laid layer by layer in the main layup area. A segmented pressure curing strategy is adopted to achieve a synergistic match between resin viscosity and fiber network compaction.
It effectively overcomes the problem of limited posture when manually laying large rotating components, avoids wrinkles, insufficient glue, excessive glue and pore defects in the R-corner area, reduces internal residual stress and curing deformation, and achieves stable manufacturing of outer casing with high efficiency, high consistency and high pass rate.
Smart Images
Figure CN123040384A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-performance composite material component manufacturing technology, and discloses a molding method for an integral casing of a resin-based composite material outer casing for an aero-engine. Background Technology
[0002] Resin-based composite materials, due to their high specific strength, high specific modulus, and strong design flexibility, have been widely used in important structures such as the outer bypass casing of aero-engines. As a large, thin-walled, rotating composite material component, the manufacturing quality of the aero-engine outer bypass casing directly affects the engine's performance and reliability.
[0003] Currently, the mainstream manufacturing process for composite duct casings is autoclave molding, but this method faces the following technical bottlenecks: First, during the installation phase, traditional molds are mostly fixed or simple frame-type. Fixed molds require operators to maintain unnatural postures such as looking up or bending over for extended periods when installing the casing in areas such as the mounting edges, which not only increases labor intensity but also seriously affects installation accuracy and efficiency.
[0004] Secondly, in the R-corner (transition fillet) area of the component, due to the abrupt change in geometric curvature, the prepreg is prone to wrinkling and bridging, leading to defects such as insufficient or excessive prepreg or porosity in this area after curing, making it a weak point in quality. Existing filling technologies mostly use prepreg tows or simply stacked sheets. Prepreg tows have poor internal permeability and are prone to trapping air bubbles, resulting in high porosity at the root. Directly stacking sheets makes it difficult to ensure perfect adhesion to curved surfaces and easily leads to bridging.
[0005] Finally, during the curing stage, the curing reaction of resin-based composite materials is closely related to the temperature and pressure history. Traditional curing strategies often fail to precisely match the requirements of resin viscosity changes and fiber network compaction, resulting in high residual stress inside the component, warping, springback, and other deformations after demolding, making it difficult to guarantee dimensional accuracy and leading to poor product consistency.
[0006] While some improvements have emerged in existing technologies, such as using multiple sets of support rollers on the top of the bracket to support and drive the mold rotation, these solutions still suffer from relatively complex structures, reliance on the precise coordination and synchronization of multiple rollers, and limited operational flexibility. Other technical solutions focus on the preparation and application of "pre-formed R-corner filling blocks" to address R-corner defects; however, these filling blocks require pre-heat pressing in a specialized mold, resulting in a long process and limited adaptability to complex curved surfaces.
[0007] In summary, existing technologies have not yet provided a rotary mold solution with an extremely simple structure and highly user-friendly operation, nor a radius-filling technology that can be rapidly prepared on-site and achieve perfect fit and dense filling through active control of fiber orientation, coupled with a curing process that precisely controls deformation. Therefore, there is an urgent need for an integrated and innovative solution to systematically improve the manufacturing quality and efficiency of the outer casing. Summary of the Invention
[0008] The purpose of this invention is to provide a molding method for an integral casing of a resin-based composite material outer casing for aero-engines, in order to solve the problems of low efficiency and poor quality consistency caused by the limited posture of manual laying in the manufacturing of large rotating composite material components, wrinkles and defects of poor and rich glue due to uneven material accumulation or bridging in complex R-corner areas, and large residual stress and obvious deformation caused by the mismatch of temperature-pressure curves during curing. This invention aims to achieve stable manufacturing of outer casing components with high efficiency, high consistency and high pass rate.
[0009] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A method for molding an integral casing of a resin-based composite outer casing for an aero-engine, utilizing a horizontal rotary molding die, wherein the molding area of the horizontal rotary molding die includes a casing body layup area and a radius filler area, comprising the following steps: S1: Cut the prepreg sheet into narrow strips and apply a twist to the narrow strips about their length to make a flexible filler strip with a predetermined fiber helical orientation, the fiber helical orientation being controlled by a twist parameter; S2: In the R-corner area of the molding die, the flexible filler strip is used to fill and compact the R-corner filler layer by layer in a pyramid shape to form an R-corner filler body; the flexible filler strip is not pre-compacted before filling and is directly filled layer by layer in the R-corner area of the molding die in an uncured state; each layer of the pyramid-shaped filler strip is compacted along the R-corner curved surface direction with a pressure roller after being laid. S3: By rotating the molding die, prepreg sheets are laid layer by layer in the main body layup area of the casing to form the main body layup. At the same time, the main body layup of the casing is smoothly combined with the R-corner filler to obtain the outer bypass casing preform. S4: The horizontal rotary molding mold including the outer bypass casing preform is cured in an autoclave, and then demolded to obtain the outer bypass casing.
[0010] Furthermore, the torsion of the fiber helical orientation is controlled to be 3 r / cm ≤ n ≤ 5 r / cm.
[0011] Furthermore, the maximum helix angle θmax of the prepreg fibers in the flexible filler strip at the narrow strip edge satisfies 62°≤θmax≤86°.
[0012] Furthermore, the autoclave curing is a segmented pressure curing process, wherein the first stage of pressure curing applies a first pressure within a first temperature range and maintains the pressure for a first preset time, and the second stage applies a second pressure within a second temperature range and maintains the pressure for a second preset time, thereby completing the curing process; the second temperature range is higher than the first temperature range, and the second pressure is greater than the first pressure; the first pressure is applied when the resin viscosity is in the initial decrease phase, and the second pressure is applied when the resin is in the early stage of gelation.
[0013] Furthermore, the horizontal rotary forming mold includes: The cylindrical section has an upper convex ring and a lower convex ring on its outer wall surface. The upper convex ring and the outer wall surface, and the lower convex ring and the outer wall surface, are each provided with an R-angle filling area, corresponding to the R-angle of the casing. The outer wall surface between the two R-angle filling areas is the main body layup area of the casing, corresponding to the non-R-angle area of the casing. The R-angle filling area and the main body layup area of the casing constitute the forming area of the horizontal rotary molding die. A fixed bracket is provided, which is equipped with a rotating support mechanism. The rotating support mechanism is used to support both ends of the cylindrical section and enable the cylindrical section to rotate freely or be locked around the horizontal axis.
[0014] Furthermore, the rotating support mechanism includes a front support and a rear support; the front support is used for the front end of the rolling support cylindrical section, and the rear support is used for the rear end of the rolling support cylindrical section.
[0015] Furthermore, both the front support and the rear support include two support seats and bearings. The two support seats are fixed on a fixed bracket and are symmetrically distributed on both sides of the horizontal axis of the cylindrical section. The bearings are installed on the support seats and make rolling contact with the outer wall of the cylindrical section.
[0016] Furthermore, the rotating support mechanism also includes an angle positioning locking pin and a locking base; the locking base is fixed on the fixed bracket; the angle positioning locking pin is threadedly connected to the locking base and is used to insert into the positioning hole on the end face of the cylindrical section to lock the cylindrical section.
[0017] Compared with the prior art, the beneficial effects of this invention are: This invention involves cutting prepreg sheets into narrow strips and applying a twist along their length to create flexible filler strips with fiber helical orientation controlled by a twist parameter. These strips are then directly filled in the uncured, pyramidal shape layer by layer in the R-corner area of a horizontal rotary molding die. Each layer is compacted along the R-corner surface using a pressure roller. The prepreg sheets are then layered onto the main body of the casing using the rotating die, ensuring a smooth bond between the main body layup and the R-corner filler. Finally, the entire precast body is cured in an autoclave and demolded. This method effectively overcomes the limitations of manual laying of large rotating components by utilizing the rotation of the die around a horizontal axis during the laying stage, ensuring the surface to be laid is always in a convenient position for operation. The limitations of the bonding posture lead to low efficiency and poor quality consistency. At the same time, the helical fiber orientation of the flexible filler strip gives it good flexibility and conformal bonding ability. Combined with pyramid-shaped layer-by-layer filling and compaction, it can fundamentally avoid wrinkles, insufficient glue, excessive glue, and pore defects in the R-corner area due to uneven material accumulation or bridging. Moreover, after the bonding is completed, it can be put into the can for curing as a whole without disassembling the mold components. This facilitates the matching of temperature and pressure regimes with resin viscosity changes and fiber network compaction requirements during the curing process, reducing internal residual stress and curing deformation. Ultimately, it can achieve stable manufacturing of outer casing components with high efficiency, high consistency, and high yield. Attached Figure Description
[0018] Figure 1 This is a flowchart illustrating the molding method of the integral casing of the resin-based composite outer casing of an aero-engine in the embodiment. Figure 2 This is a schematic diagram of the horizontal rotary molding die for the integral casing of the resin-based composite outer casing of an aero-engine in the embodiment. Figure 3 This is a schematic diagram of the pyramid-shaped filling of the flexible filler strip in the embodiment; Among them, 1-cylinder section body, 2-fixed bracket, 3-rotating support mechanism, 31-support seat, 32-bearing, 41-upper convex ring, 42-lower convex ring, 5-vacuum pipe, 61-casing body layer area, 62-R-angle filling area, 63-upper auxiliary wall, 64-lower auxiliary wall. Detailed Implementation
[0019] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.
[0020] See Figure 1 This invention provides a molding method for an integral casing of a resin-based composite outer casing for an aero-engine, which is achieved using a horizontal rotary molding die. The molding area of the horizontal rotary molding die consists of a casing body layup area 61 and a radius corner filling area 62, and includes the following steps: S1: Cut the prepreg sheet into narrow strips and apply a twist to the narrow strips about their length to make a flexible filler strip with a predetermined fiber helical orientation, the fiber helical orientation being controlled by a twist parameter; S2: In the R-corner area of the molding die, the flexible filler strip is used to fill and compact the R-corner filler layer by layer in a pyramid shape to form an R-corner filler body; the flexible filler strip is not pre-compacted before filling and is directly filled layer by layer in the R-corner area of the molding die in an uncured state; each layer of the pyramid-shaped filler strip is compacted along the R-corner curved surface direction with a pressure roller after being laid. S3: By rotating the molding die, prepreg sheets are laid layer by layer in the main body layup area 61 of the casing to form the main body layup. At the same time, the main body layup of the casing is smoothly combined with the R-corner filler to obtain the outer bypass casing preform. S4: The horizontal rotary molding mold including the outer bypass casing preform is cured in an autoclave, and then demolded to obtain the outer bypass casing.
[0021] This invention creates flexible filler strips by cutting prepreg sheets into narrow strips and applying a twist around their length, resulting in a fiber helical orientation controlled by a twist parameter. These strips are then directly filled in the R-corner region of a horizontal rotary molding die in an uncured state, layer by layer in a pyramid shape. Each layer is compacted along the R-corner surface using a pressure roller. The prepreg sheets are then layered in the main body layup area 61 of the casing using the rotating die, ensuring a smooth bond between the main layup and the R-corner filler. Finally, the entire precast body is cured in an autoclave and demolded. This method, by rotating the die around a horizontal axis during the laying stage, ensures the surface to be laid is always in a convenient position for operation, effectively overcoming the limitations of manual handling of large rotating components. The limitations of the laying posture lead to low efficiency and poor quality consistency. At the same time, the helical fiber orientation of the flexible filler strip gives it good flexibility and conformal bonding ability. Combined with pyramid-shaped layer-by-layer filling and compaction, it can fundamentally avoid wrinkles, insufficient glue, excessive glue, and pore defects in the R-corner area due to uneven material accumulation or bridging. Moreover, after laying, the entire unit can be put into the can for curing without disassembling the mold components. This facilitates the coordinated matching of temperature and pressure regimes during the curing process with changes in resin viscosity and the compaction requirements of the fiber network, reducing internal residual stress and curing deformation. Ultimately, it enables the stable manufacturing of the outer casing components with high efficiency, high consistency, and high yield.
[0022] Example This embodiment further elaborates on the detailed method for molding the integral casing of the resin-based composite outer casing of an aero-engine, as follows.
[0023] See Figure 2The molding method of the integral casing of the aero-engine resin-based composite material outer casing utilizes a horizontal rotary molding die, including: cylindrical body 1, upper convex ring 41, lower convex ring 42, fixed bracket 2 and rotary support mechanism 3.
[0024] The outer wall of the cylindrical section 1 is provided with an upper convex ring 41 and a lower convex ring 42. An R-angle filling area corresponding to the R-angle of the casing is provided between the outer wall surfaces of the upper convex ring 41 and between the lower convex ring 42 and the outer wall surface. The outer wall surface between the two R-angle filling areas is the casing body layup area corresponding to the non-R-angle area of the casing. The R-angle filling area and the casing body layup area constitute the forming area of the horizontal rotary molding die. During casing fabrication, the R-angle filling area is used to fill a flexible filler strip with a predetermined fiber helical orientation structure to form an R-angle filler. The casing body layup area is used to lay prepreg sheets to form the casing body, and a smooth transition occurs at the junction of the casing body and the R-angle filler.
[0025] Furthermore, on the outer wall surface of the cylindrical body 1, the outer wall surface between the upper convex ring 41 and the upper port is the upper auxiliary wall surface 63, and the outer wall surface between the lower convex ring 42 and the lower port is the lower auxiliary wall surface 64. The upper and lower auxiliary walls are used for rolling contact with the rotating support mechanism 3. Moreover, a vacuum connector 5 is provided on the inner wall of the cylindrical body 1. Both the upper auxiliary wall surface 63 and the lower auxiliary wall surface 64 are provided with vacuum suction holes. If the upper auxiliary wall surface is provided with a vacuum suction hole, the vacuum suction hole is connected to the vacuum connector on the inner wall of the upper port of the cylindrical body 1; if the lower auxiliary wall surface is provided with a vacuum suction hole, the vacuum suction hole is connected to the vacuum connector on the inner wall of the lower port of the cylindrical body 1. During vacuum pre-compression of the R-corner filling area and during vacuum sealing of the entire cylindrical body 1 in a bag, the vacuum pump is connected to the vacuum connector to achieve vacuuming of the R-corner filling area and vacuuming of the entire cylindrical body 1 in a bag.
[0026] The rotating support mechanism 3 is mounted on the fixed bracket 2 and is used to support both ends of the cylindrical section 1, allowing the cylindrical section 1 to rotate freely or be locked around the horizontal axis. Specifically, the rotating support mechanism 3 includes a front support and a rear support; the front support is used to roll support the front end of the cylindrical section 1, and the rear support is used to roll support the rear end of the cylindrical section 1.
[0027] Furthermore, the front and rear supports have identical structures, each including two support seats 31 and bearings 32. The two support seats 31 are fixed to the fixed bracket 2 and symmetrically distributed on both sides of the horizontal axis of the cylindrical body 1. The bearings 32 are mounted on the support seats 31 and roll in contact with the outer wall of the cylindrical body 1. During the laying process, the operator can freely rotate the cylindrical body 1 as needed to ensure that the laying surface is always in the optimal working position, completely eliminating abnormal posture operations, reducing labor intensity, and improving laying accuracy and efficiency.
[0028] Furthermore, the rotating support mechanism 3 also includes an angle positioning locking pin and a locking base; the locking base is fixed on the fixed bracket 2; the angle positioning locking pin is threadedly connected to the locking base and is used to insert into the positioning hole on the end face of the cylindrical section 1 to lock the cylindrical section 1. In this embodiment, a positioning hole is opened every 45° on the end face of the cylindrical section 1, and the number of positioning holes can be increased or decreased as needed. During the laying process, after the cylindrical section 1 is rotated to the required position, the angle positioning locking pin is tightened so that the angle positioning locking pin is inserted into one of the positioning holes to lock the cylindrical section 1, facilitating laying. When the current laying surface has been completed and the next laying surface needs to be laid, the angle positioning locking pin is loosened so that the angle positioning locking pin exits the positioning hole to unlock the cylindrical section 1, and then the cylindrical section 1 is rotated. When it is rotated into place, the cylindrical section 1 is locked again.
[0029] See Figure 1 The molding method for the integral casing of the aero-engine resin-based composite outer casing in this embodiment utilizes the molding die described above. This embodiment takes the fabrication of a certain type of aero-engine outer casing as an example, using carbon fiber / epoxy resin prepreg as the material. The molding method includes the following steps: S1: Production preparation and material cutting Prepreg is retrieved from a -18℃ freezer and thawed for at least 12 hours in a clean room at 22±3℃ and humidity <30%, and then unsealed after confirming there is no condensation. The mold surface is thoroughly cleaned with acetone and coated with three layers of release agent. Based on the design software, the 3D digital model of the outer duct casing is used for layup development and layup suitability simulation to generate a blanking drawing, and an automatic blanking machine is used for precise blanking.
[0030] S2: Preparation of Flexible Fillers Prepreg sheet is cut into narrow strips and twisted about its length to form a flexible filler strip with a predetermined fiber helical orientation, which is controlled by a torsion parameter.
[0031] Specifically, based on the design value of the radius (R) angle of the outer casing, the required prepreg width for fabricating the flexible filler strip is calculated. The width of the prepreg narrow strip is 2~10mm, and the thickness is 0.1~0.3mm; the applied torsion n (number of torsion turns per unit length) is controlled to be 3 r / cm ≤ n ≤ 5 r / cm, so that the maximum helix angle of the prepreg fibers in the flexible filler strip at the edge of the narrow strip is maximized. θmax Satisfy: 62°≤ θmax ≤86°, of which θmax = arctan(π·n·w) ,in, wThe width is narrow. The specified helix angle range ensures that the fibers provide sufficient lateral reinforcement to resist interlaminar shear while avoiding fiber damage due to excessive twisting. In this embodiment, the prepreg is cut into narrow strips with a width of 5mm, clamped at both ends, and twisted in the opposite direction to form a flexible filler strip that can be bent at will.
[0032] S3: Filling the R-corner area of the installation edge See Figure 3 In the R-corner area of the molding die, the flexible filler strips are used to fill and compact the area layer by layer in a pyramid shape to form an R-corner filler body. The flexible filler strips are not pre-compacted before filling; they are directly filled layer by layer in the R-corner area of the molding die in an uncured state. Each layer of the pyramid-shaped filler strips is compacted along the R-corner curved surface using a pressure roller after laying. Furthermore, the vacuum pre-compaction time is no less than 15 minutes.
[0033] Specifically, in the R-corner area of the cylindrical section, flexible filler strips are used to fill the area layer by layer in a pyramid shape, starting from the bottom. After filling, a flexible pressure equalizing plate made of silicone rubber is placed on top, and a vacuum is drawn to -0.085MPa. The pressure is maintained for 20 minutes for pre-compaction to form the R-corner filler.
[0034] S4: Laying on a horizontal rotary forming mold By rotating the molding die, prepreg sheets are laid layer by layer in the main body layup area of the casing to form the main body layup. At the same time, the main body layup of the casing is smoothly combined with the R-corner filler to obtain the outer bypass casing preform.
[0035] Specifically, the cylindrical section 1 is mounted on a fixed bracket via rotating support mechanisms at both ends. The operator can easily rotate the cylindrical section 1 to the most comfortable position according to the layup sequence, and then sequentially lays the automatically fed sheets. When the layup reaches the point of engagement with the radius-angle infill area, ensure a smooth transition between the layup and the infill.
[0036] S5: The horizontal rotary molding mold including the outer bypass casing preform is cured in an autoclave, and then demolded to obtain the outer bypass casing.
[0037] The specific steps involved in implementing this procedure are as follows: S51: Bag making and curing After the paving is completed, high-temperature sealing strips are pasted on the edges of the cylindrical section 1, and auxiliary materials such as isolation film and breathable felt are laid in sequence. Then, the cylindrical section (1) is completely sealed with vacuum bag film, and vacuum is drawn through vacuum pipe. Finally, the vacuum-sealed cylindrical section (1) is placed on the fixed bracket 2, and the horizontal rotary molding mold is pushed into the autoclave for hot pressing and curing.
[0038] Furthermore, the hot-press curing is a segmented pressure curing process. The first segment applies a first pressure at a first temperature plateau and holds it there; the second segment applies a second, higher pressure at a second, higher temperature plateau and holds it there, ultimately completing the curing process. Specifically, the segmented pressure curing process involves: heating to a first temperature plateau of 50-70°C at a rate of 0.5-3°C / min, holding at a first pressure of 0.2-0.4 MPa for 30±10 minutes; then continuing to heat to a second temperature plateau of 110-130°C at a rate of 0.5-3°C / min, holding at a second pressure of 0.5-0.7 MPa for 30±10 minutes; finally, heating to the corresponding curing temperature of the resin system to complete the final curing. The first pressure is applied when the resin viscosity is in the initial decrease phase, and the second pressure is applied during the early stage of resin gelation.
[0039] In this embodiment, the following segmented pressure curing strategy is implemented: the tank pressure is increased to 0.3 MPa (first pressure plateau) at a rate of 0.05 MPa / min, then the temperature is increased to 60°C at a rate of 2°C / min and held for 30 min; next, the tank pressure is increased to 0.6 MPa (second pressure plateau) at a rate of 0.04 MPa / min, and the temperature is increased to 120°C at a rate of 2°C / min and held for 30 min; finally, the temperature is increased to 180°C and held for 120 min to complete curing. After pressure curing, the temperature is reduced to below 60°C at a rate of 1.5°C / min, and the pressure is released from the oven.
[0040] It should be noted that in this invention, the horizontal rotary molding die, the torsion narrow-band flexible filler strip, and the segmented pressure curing strategy are functionally interdependent and technologically causally related, forming an inseparable overall technical solution. Specifically: the rotary support mechanism allows the operator to rotate any surface to be laid on the inner wall of the cylindrical section to the optimal working position. This operational freedom provides the technological feasibility for the "on-site preparation—layer-by-layer filling—shape-following compaction" of the R-corner filler strip; while the fibers in the torsion filler strip are arranged in a helical orientation, and the densification of its internal fiber network is relatively sensitive to pressure transmission. Therefore, during the curing stage, a lower first pressure must be applied at a first temperature plateau where the resin viscosity is low, allowing the resin to fully wet the fibers and expel air bubbles. A higher second pressure is then applied when the resin viscosity begins to rise to the pre-gelation stage, completing the final compaction before the resin loses its fluidity. Therefore, the segmented pressure curing strategy of this invention is specifically designed for R-corner areas containing torsion filler strips and is fundamentally different from conventional segmented curing strategies.
[0041] S52: Demolding Open the vacuum bag and remove auxiliary materials such as the vacuum bag film and breathable felt. Remove the upper and lower convex rings 42 of the molding die to separate the cured casing parts from the die, thus obtaining the outer bypass casing.
[0042] This invention employs a horizontal rotary molding die with a bottom-mounted rotating support mechanism. A narrow strip of prepreg is twisted to a predetermined degree to create a flexible filler strip with controllable fiber helical orientation and conformal bending capability. Under the rotational positioning of the cylindrical section, the filler strip is layered in a pyramid shape, filling the rounded corners and laying it onto the sheet material, supplemented by vacuum pre-compacting with a flexible pressure equalizing plate. Subsequently, a pre-set pressure-temperature coupled segmented curing strategy is used for autoclave curing. The die utilizes a simple rotary support mechanism to allow the cylindrical section to rotate and lock at any angle around a horizontal axis. This invention solves the technical problems of low efficiency and quality due to limited laying posture of large rotating components, difficulty in controlling defects in complex rounded corner areas, and significant deformation during the curing process, achieving efficient, high-quality, and highly consistent manufacturing of the outer casing.
[0043] Compared with the prior art, the present invention has at least the following technical effects: (1) The horizontal rotary molding die provided by the present invention has a simple and reliable structure. The operator can keep the paving surface in the optimal working position by manually rotating the die, which completely eliminates abnormal posture operation, significantly reduces labor intensity, and improves paving accuracy and efficiency. At the same time, the molding die does not require disassembly of any parts after paving and can be directly put into the can for curing, which simplifies the process and improves operation safety.
[0044] (2) The “torsional narrow-band flexible filler strip” of the present invention constructs a fiber spatial network with a controllable helical angle inside the filler by precisely controlling the torsion degree. This structure, on the one hand, gives the filler strip itself good flexibility and conformability, enabling it to seamlessly fit the R-corner curved surface of the mold, eliminating wrinkles and bridging at the source; on the other hand, the fibers are no longer arranged along a single axis, but generate a significant transverse component, effectively improving the interlayer shear resistance of the R-corner region. Combined with pyramid-shaped layer-by-layer stacking and vacuum pre-compaction with a flexible equalizing plate, air can be effectively removed and the material can be initially compacted before curing, so that the R-corner region reaches a dense state before curing. Using the method of the present invention, the porosity of the R-corner region can be stably controlled below 0.5%. Compared with traditional filling methods, this method can quickly prepare fillers on-site without adding extra steps, and has stronger process adaptability.
[0045] (3) Effective control of curing deformation: The segmented pressure curing method designed in this invention uses pressure application points that coincide with key changes in resin viscosity. The first pressure plateau acts during the initial viscosity decrease period of the resin, promoting resin flow and fiber wetting; the second, higher pressure plateau acts during the early stage of resin gelation, further compacting the structure and expelling residual volatiles. This segmented pressure curing method effectively coordinates the relationship between flow, compaction, and reaction, significantly reducing internal residual stress and effectively controlling curing deformation.
[0046] (4) The horizontal rotary molding die, the torsion filler strip, and the segmented curing of the present invention constitute an inseparable whole: the rotary die provides operational freedom for on-site filling of the R-corner area; the fiber helical orientation structure of the torsion filler strip requires that the curing must match it; and the pressure-temperature coupling strategy of segmented curing, in turn, ensures the compaction and low porosity of the torsion filler strip in the R-corner area. The three work together to achieve stable manufacturing of the outer casing with high efficiency, high consistency, and high yield.
[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A molding method for an integral casing of a resin-based composite outer casing for an aero-engine, achieved using a horizontal rotary molding die, wherein the molding area of the horizontal rotary molding die includes a casing body layup area and a radius filler area, characterized in that, Includes the following steps: S1: Cut the prepreg sheet into narrow strips and apply a twist to the narrow strips about their length to make a flexible filler strip with a predetermined fiber helical orientation, the fiber helical orientation being controlled by a twist parameter; S2: In the R-corner area of the molding die, the flexible filler strip is used to fill and compact the R-corner filler layer by layer in a pyramid shape to form an R-corner filler body; the flexible filler strip is not pre-compacted before filling and is directly filled layer by layer in the R-corner area of the molding die in an uncured state; each layer of the pyramid-shaped filler strip is compacted along the R-corner curved surface direction with a pressure roller after being laid. S3: By rotating the molding die, prepreg sheets are laid layer by layer in the main body layup area (61) of the casing to form the main body layup, and the main body layup of the casing is smoothly combined with the R-corner filler to obtain the outer casing preform. S4: The horizontal rotary molding mold including the outer bypass casing preform is cured in an autoclave, and then demolded to obtain the outer bypass casing.
2. The molding method according to claim 1, characterized in that, The twist of the fiber helical orientation is controlled to be 3r / cm≤n≤5r / cm.
3. The molding method according to claim 2, characterized in that, The maximum helix angle of the prepreg fibers at the narrow band edge in the flexible filler strip θmax Satisfying 62°≤ θmax ≤86°.
4. The molding method according to claim 3, characterized in that, The autoclave curing is a segmented pressure curing process, wherein the first segment of pressure curing applies a first pressure within a first temperature range and maintains the pressure for a first preset time, and the second segment applies a second pressure within a second temperature range and maintains the pressure for a second preset time, thereby completing the curing process. The second temperature range is higher than the first temperature range, and the second pressure is greater than the first pressure.
5. The molding method according to claim 1, characterized in that, The horizontal rotary forming mold includes: A cylindrical section (1) has an upper convex ring (41) and a lower convex ring (42) on its outer wall surface. The upper convex ring (41) and the outer wall surface, and the lower convex ring (42) and the outer wall surface are each provided with an R-angle filling area, which corresponds to the R-angle of the casing. The outer wall surface between the two R-angle filling areas is the main body layup area of the casing, which corresponds to the non-R-angle area of the casing. The R-angle filling area and the main body layup area of the casing constitute the forming area of the horizontal rotary molding die. A fixed bracket (2) is provided with a rotating support mechanism (3), which is used to support both ends of the cylindrical section body (1) and enable the cylindrical section body (1) to rotate freely or be locked around the horizontal axis.
6. The molding method according to claim 5, characterized in that, The rotating support mechanism (3) includes a front support and a rear support; the front support is used for the front end of the rolling support cylindrical section (1), and the rear support is used for the rear end of the rolling support cylindrical section (1).
7. The molding method according to claim 6, characterized in that, Both the front support and the rear support include two support seats (31) and bearings (32). The two support seats (31) are fixed on the fixed bracket (2) and are symmetrically distributed on both sides of the horizontal axis of the cylindrical body (1). The bearings (32) are installed on the support seats (31) and make rolling contact with the outer wall of the cylindrical body (1).
8. The molding method according to claim 7, characterized in that, The rotating support mechanism (3) further includes an angle positioning locking pin and a locking base; the locking base is fixed on the fixed bracket (2); the angle positioning locking pin is threadedly connected to the locking base and is used to insert into the positioning hole on the end face of the cylindrical section (1) to lock the cylindrical section (1).