A composite propeller blade RTM mold structure

Abstract

This application relates to an RTM mold structure for composite material propeller blades, including an upper mold, a lower mold, and a sealing strip. The upper mold has a protrusion protruding from the parting surface, and a first mold cavity matching the upper contour of the blade is formed on the inner side of the protrusion. The lower mold has a recessed portion recessed into the parting surface, and a second mold cavity matching the lower contour of the blade is formed on the inner side of the recess. After the lower mold and the upper mold are engaged along the parting surface, the first mold cavity and the second mold cavity are joined to form a complete mold cavity for molding the propeller blade. The sealing strip is disposed on the contact side of the recessed portion and the protrusion. The upper mold is a protrusion protruding from the parting surface, and the lower mold is a recessed portion recessed into the parting surface. The lower mold aligns with the upper mold to form a circumferential limit. Compared with the traditional guide post and guide sleeve positioning method, the positioning accuracy is greatly improved, effectively preventing the relative displacement of the upper and lower molds during pressurization and heating, and ensuring the accuracy of the blade shape. At the same time, the sealing strip is disposed on the contact side of the recessed portion and the protrusion, replacing the traditional parting surface sealing structure, resulting in a more stable sealing effect.

Description

Technical Field

[0001] This application relates to the field of composite material molding die technology, and in particular to a composite material propeller blade RTM die structure. Background Technology

[0002] Propeller blades are the core components of a propeller system, converting the engine's rotational power into thrust or pull for aircraft flight. They withstand significant centrifugal loads during operation, thus requiring extremely high molding quality standards for internal density and dimensional accuracy. Currently, composite material propeller blades are primarily molded using resin transfer molding (RTM), a process that sequentially includes preform laying, mold closing and clamping, resin impregnation and curing, and demolding.

[0003] In existing technologies, RTM molds for composite propeller blades mostly adopt traditional split-mold structures. The sealing of the mold mainly relies on sealing strips set at the parting surface. However, the airtightness inside the mold is easily affected by uneven distribution of clamping force and inconsistent gap size, which can lead to fluctuations in mold airtightness. This can result in internal defects such as bubbles and pores after the blade is formed, reducing the quality of the formed blade. At the same time, the positioning accuracy of traditional split-mold structures depends on the fit of guide pillars and guide sleeves. During the clamping, pressurization, and heating curing processes, relative displacement between the upper and lower molds can easily occur, further affecting the shape accuracy of the blade and failing to meet the forming requirements of high-precision composite propeller blades.

[0004] To address the aforementioned technical problems, this invention designs an embedded composite material propeller blade RTM mold. By optimizing the fit between the upper and lower mold structures and the installation position of the sealing strip, and by adding pressure compensation and dynamic gap compensation structures, the problem of mold airtightness fluctuation caused by uneven mold closing pressure and gap is fundamentally solved. At the same time, the mold positioning accuracy is improved, ensuring the quality of blade forming. Summary of the Invention

[0005] This application provides a composite material propeller blade RTM mold structure to solve the problems of uneven mold closing pressure and clearance, easy fluctuation of air tightness, and insufficient positioning accuracy of traditional split mold structure RTM molds in the prior art. It improves the sealing stability and positioning accuracy of the mold, thereby ensuring the molding quality of composite material propeller blades and reducing the internal defect rate of the blades.

[0006] This application provides a composite material propeller blade RTM mold structure, including an upper mold, a lower mold, and a sealing strip; the upper mold has a protrusion protruding from the parting surface, and a first mold cavity matching the upper contour of the blade is formed on the inner side of the protrusion; the lower mold has a recess recessed into the parting surface, and a second mold cavity matching the lower contour of the blade is formed on the inner side of the recess; after the lower mold and the upper mold are engaged along the parting surface, the first mold cavity and the second mold cavity are spliced ​​to form a complete mold cavity for molding the propeller blade; the sealing strip is disposed on the contact side of the recess and the protrusion to achieve sealing after the upper and lower molds are engaged, replacing the traditional parting surface sealing form and improving sealing reliability.

[0007] Furthermore, a sealing groove is provided on the contact side of the protrusion, and the sealing strip is fitted into the sealing groove to achieve fixed installation of the sealing strip, prevent the sealing strip from moving during mold closing and molding, and ensure the sealing effect.

[0008] Furthermore, the convex and concave parts are rectangular structures that match the outer periphery of the blade. The inner wall of the concave part and the outer wall of the convex part are fitted with a clearance, so that the concave part of the lower mold aligns with the convex part of the upper mold to form a circumferential limit, thereby improving the positioning accuracy of the upper and lower molds and preventing relative displacement of the upper and lower molds during pressurization and heating.

[0009] Furthermore, the bottom of the sealing groove is equipped with a piezoelectric ceramic expansion joint and a gap sensor. The piezoelectric ceramic expansion joint and the gap sensor are electrically connected. The gap sensor is used to collect the gap data between the sealing strip and the bottom of the sealing groove in real time. When the collected gap data exceeds the set threshold, the external controller drives the piezoelectric ceramic expansion joint to extend and push the sealing strip to the outside to achieve dynamic gap compensation between the sealing strip and the inner wall of the recess, so as to avoid the airtightness reduction caused by excessive sealing gap.

[0010] Furthermore, the bottom of the sealing groove is provided with multiple slots spaced apart circumferentially, and the piezoelectric ceramic expansion joints are embedded in the slots one by one, so as to realize the uniform distributed installation of the piezoelectric ceramic expansion joints, ensure the uniformity of gap compensation at each position, and avoid the problem of inadequate local compensation.

[0011] Furthermore, a reserved groove is provided on the outer periphery of the concave part located in the second mold cavity, and a buffer substrate is adapted to be installed in the reserved groove. The buffer substrate is made of flexible material. During the mold closing and pressurization process, the buffer substrate can offset the pressure difference at different positions of the contact surface between the concave and convex parts through its own deformation, so that the pressure distribution at the contact part of the upper and lower molds is uniform, and the sealing failure caused by excessive or insufficient local pressure is avoided.

[0012] Furthermore, the buffer matrix is ​​made of ultra-elastic polyurethane material, which has both good elastic deformation capacity and compressive strength. It can achieve effective deformation compensation under the action of mold closing pressure and is not prone to plastic deformation, ensuring long-term use effect.

[0013] Furthermore, the buffer substrate has a honeycomb structure, with multiple independent honeycomb chambers inside. The honeycomb structure can ensure the uniformity of deformation of the buffer substrate, avoid local collapse, and ensure the consistency of pressure compensation throughout the circumference.

[0014] Furthermore, the honeycomb cavity is filled with a flowing medium, which can absorb the impact force during the mold closing process. At the same time, through its own flow within the honeycomb cavity, it further optimizes the pressure transmission effect of the buffer matrix and improves the pressure distribution capability. Preferably, the flowing medium is high-viscosity silicone oil, which has excellent damping characteristics, good energy absorption effect, and moderate fluidity, and can achieve uniform pressure transmission within the honeycomb cavity.

[0015] Furthermore, the opening of the reserved groove is covered with a thin plate, which fits tightly against the upper surface of the buffer substrate, thus limiting and sealing the buffer substrate and preventing it from moving upwards during the molding and pressurization process. At the same time, it prevents the high-viscosity silicone oil filled in from overflowing from the honeycomb cavity, ensuring the structural integrity and performance of the buffer substrate.

[0016] The beneficial effects of this application are as follows: The composite material propeller blade RTM mold structure of this application features an upper mold with a protrusion protruding from the parting surface and a lower mold with a recessed parting surface. The inner wall of the recess and the outer wall of the protrusion are fitted with a clearance. The lower mold aligns with the upper mold to form a circumferential limit. Compared with the traditional guide post and guide sleeve positioning method, the positioning accuracy is greatly improved, effectively preventing the relative displacement of the upper and lower molds during pressurization and heating, and ensuring the accuracy of the blade shape. At the same time, the sealing strip is set on the contact side of the recess and the protrusion, replacing the traditional parting surface sealing method, and the sealing effect is more stable.

[0017] By setting piezoelectric ceramic expansion plates and gap sensors at the bottom of the sealing groove, dynamic gap compensation between the sealing strip and the inner wall of the recess is achieved. The sealing gap can be monitored in real time and compensation can be made in a timely manner, which fundamentally solves the problem of excessive sealing gap caused by mold deformation and sealing strip creep during the molding process, and ensures the stability of mold airtightness.

[0018] A honeycomb structure buffer substrate is set on the outer periphery of the second mold cavity in the lower mold recess, and high viscosity silicone oil is filled in the honeycomb cavity. When the mold is closed and pressure is applied, the buffer substrate can absorb energy through elastic deformation combined with the flow of silicone oil, effectively offsetting the pressure difference between the upper and lower mold contact surfaces, so that the mold closing pressure is evenly distributed, avoiding the deformation and failure of the sealing strip or the poor sealing fit caused by excessive or insufficient local pressure, and solving the problem of air tightness fluctuation caused by uneven mold closing pressure. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the upper mold of the composite material propeller blade RTM mold structure provided in the embodiments of this application; Figure 2 This is a schematic diagram of the lower mold of the composite material propeller blade RTM mold structure provided in the embodiments of this application; Figure 3 A cross-sectional view of the composite material propeller blade RTM mold structure provided in the embodiments of this application; Figure 4 This is a cross-sectional view of the RTM mold structure for composite material propeller blades in the prior art; Figure 5 This is a schematic diagram of the structure of a piezoelectric ceramic telescopic sheet; Figure 6 This is a schematic diagram of the buffer matrix.

[0021] Figure label: 1. Upper mold; 11. Protrusion; 12. First mold cavity; 13. Sealing groove; 14. Plate groove; 2. Lower mold; 21. Recess; 22. Second mold cavity; 23. Reserved groove; 3. Sealing strip; 4. Piezoelectric ceramic telescopic plate; 5. Gap sensor; 6. Buffer base; 7. Thin plate; 8. Parting surface. Detailed Implementation

[0022] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The following is combined Figures 1-6 This describes the composite material propeller blade RTM mold structure provided in the embodiments of this application.

[0024] The composite material propeller blade RTM mold structure provided in this embodiment includes an upper mold 1, a lower mold 2, and a sealing strip 3. The upper mold 1 has an integrally formed protrusion 11 protruding from the parting surface 8 in its center. The inner curved surface of the protrusion 11 is machined to form a first mold cavity 12, the contour of which precisely matches the upper surface contour of the propeller blade. The lower mold 2 has a corresponding recess 21 recessed into the parting surface 8 in its center. The inner curved surface of the recess 21 is machined to form a second mold cavity 22, the contour of which precisely matches the lower surface contour of the propeller blade. The protrusion 11 and the recess 21 are rectangular structures adapted to the outer periphery of the propeller blade. The inner wall of the recess 21 and the outer wall of the protrusion 11 are fitted with a clearance of 0.05-0.1mm, so that the protrusion 11 of the upper mold 1 can be precisely embedded into the recess 21 of the lower mold 2. The inner wall of the recess 21 of the lower mold 2 aligns with the outer wall of the protrusion 11 of the upper mold 1 to form a circumferential limit, thereby achieving precise positioning of the upper and lower molds 2. When the upper and lower molds 2 are engaged along the parting surface 8, the first mold cavity 12 and the second mold cavity 22 are seamlessly joined to form a complete mold cavity for molding composite material propeller blades.

[0025] In some specific embodiments, a sealing groove 13 is continuously formed along the circumferential direction on the outer peripheral contact side of the protrusion 11 of the upper mold 1. The cross-section of the sealing groove 13 is rectangular. The sealing strip 3 is made of environmentally friendly self-lubricating polymer composite material. Its cross-section is adapted to the sealing groove 13. The sealing strip 3 is embedded in the sealing groove 13 as a whole. The outer surface of the sealing strip 3 protrudes from the outer peripheral side of the protrusion 11, so that after the upper and lower molds 2 are fastened, the sealing strip 3 can fit tightly against the inner wall of the recess 21 of the lower mold 2 to achieve a seal. At the bottom of the sealing groove 13, multiple plate grooves 14 are formed at equal intervals along the circumferential direction. The depth of the plate grooves 14 is 5-8mm. Each plate groove 14 is embedded with a piezoelectric ceramic telescopic plate 4. The telescopic direction of the piezoelectric ceramic telescopic plate 4 is consistent with the groove depth direction of the sealing groove 13. A gap sensor 5 is also installed at the bottom of the sealing groove 13. The detection end of the gap sensor 5 faces the sealing strip 3 and is used to collect the gap data between the sealing strip 3 and the bottom of the sealing groove 13 in real time. The gap sensor 5 and the piezoelectric ceramic expansion plate 4 are both electrically connected to the external controller through wires. When the gap sensor 5 detects that the gap between the sealing strip 3 and the bottom of the sealing groove 13 exceeds the set threshold of 0.1mm, the controller immediately sends a command to drive the piezoelectric ceramic expansion plate 4 to extend outward along the plate groove 14, pushing the sealing strip 3 to the outside and pressing it tightly, so that the sealing strip 3 and the inner wall of the recess 21 of the lower mold 2 always remain in close contact, realizing dynamic gap compensation and ensuring the sealing effect.

[0026] In some specific embodiments, a reserved groove 23 is continuously formed circumferentially on the inner side of the recess 21 of the lower mold 2, located on the outer periphery of the second mold cavity 22. The reserved groove 23 has a square cross-section, and a buffer substrate 6 is fitted inside the reserved groove 23. The buffer substrate 6 is made of ultra-elastic polyurethane material by compression molding, and its overall shape is a ring-shaped honeycomb structure that matches the reserved groove 23. The interior of the buffer substrate 6 forms multiple uniform and independent regular hexagonal honeycomb cavities. Each honeycomb cavity is filled with high-viscosity silicone oil, which fills the empty space of the honeycomb cavity, realizing uniform pressure transmission and impact absorption. At the opening of the reserved groove 23, a layer of stainless steel sheet 7 is covered. The thickness of sheet 7 is 1-2mm. The lower surface of sheet 7 is closely attached to the upper surface of the buffer substrate 6. The edge of sheet 7 is welded to the base of the lower mold 2 to limit and seal the buffer substrate 6, prevent the buffer substrate 6 from moving upward during the mold closing and pressurization process, and at the same time avoid high viscosity silicone oil from overflowing from the honeycomb cavity.

[0027] The mold usage process of this application includes, in sequence, preform laying, mold closing and clamping, resin impregnation and curing, and demolding. In the specific working process, the structural advantages of this invention are reflected in: (1) After the preform is laid, the protrusion 11 of the upper mold 1 is aligned with the concave part 21 of the lower mold 2 and fastened downwards. The gap between the inner wall of the concave part 21 and the outer wall of the protrusion 11 is used to achieve precise positioning of the upper and lower molds 2, avoiding the displacement deviation of traditional guide post and guide sleeve positioning. (2) During the mold closing and pressurization process, the external pressurizing equipment applies mold closing pressure to the mold, and the pressure is transmitted to the buffer substrate 6 at the reserved groove 23. The buffer substrate 6 undergoes elastic deformation under pressure. At the same time, the high viscosity silicone oil in the honeycomb cavity flows in the cavity under pressure. Through the deformation of the buffer substrate 6 and the flow of silicone oil, the pressure difference at different positions of the contact surface of the upper and lower molds 2 is effectively offset, so that the mold closing pressure is evenly distributed along the circumference, avoiding the plastic deformation of the sealing strip 3 caused by excessive local pressure, or the sealing strip 3 not being tightly adhered due to insufficient local pressure.

[0028] (3) During the resin injection and curing process, the gap sensor 5 detects the gap between the sealing strip 3 and the bottom of the sealing groove 13 in real time. If the gap exceeds the standard due to factors such as mold thermal expansion and contraction, resin curing pressure impact, and creep of the sealing strip 3, the piezoelectric ceramic expansion plate 4 will immediately extend under the drive of the controller, pushing the sealing strip 3 to press against the inner wall of the recess 21 of the lower mold 2, realizing dynamic gap compensation, ensuring the airtightness of the mold interior is stable, and avoiding defects such as bubbles and pores during the resin impregnation process.

[0029] (4) After the resin has cured, release the mold closing pressure, reset the piezoelectric ceramic telescopic sheet 4, separate the upper and lower molds 2, and complete the demolding of the blade. After demolding, the mold can be cleaned to prepare for the next batch of molding processing.

[0030] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0033] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0034] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A composite material propeller blade RTM mold structure, characterized in that, include: The upper mold has a protrusion protruding from the parting surface, and a first mold cavity is formed in the protrusion; The lower mold has a recessed portion in the parting surface, and a second mold cavity is formed in the recessed portion. After the lower mold and the upper mold are engaged along the parting surface, the first mold cavity and the second mold cavity form a complete mold cavity. A sealing strip is provided on the contact side of the recess and the protrusion.

2. The composite material propeller blade RTM mold structure according to claim 1, characterized in that, The contact side of the protrusion is provided with a sealing groove, and the sealing strip is disposed in the sealing groove.

3. The composite material propeller blade RTM mold structure according to claim 2, characterized in that, The convex part and the concave part are respectively rectangular in structure, and the inner wall of the concave part and the outer wall of the convex part are in clearance fit.

4. The composite material propeller blade RTM mold structure according to claim 3, characterized in that, The bottom of the sealing groove is provided with a piezoelectric ceramic telescopic plate and a gap sensor. The piezoelectric ceramic telescopic plate is electrically connected to the gap sensor. The gap sensor is used to collect the gap between the sealing strip and the bottom of the sealing groove. When the gap exceeds a set threshold, the controller drives the piezoelectric ceramic telescopic plate to extend and push the sealing strip outward to tighten.

5. The composite material propeller blade RTM mold structure according to claim 4, characterized in that, The bottom of the sealing groove is provided with multiple slots spaced apart, and the piezoelectric ceramic telescopic plates are respectively embedded in the slots.

6. A composite material propeller blade RTM mold structure according to any one of claims 1-5, characterized in that, A reserved groove is provided on the outer periphery of the recess located in the second mold cavity. A buffer base is provided in the reserved groove. The buffer base is made of flexible material. When the mold is closed and pressure is applied, the buffer base cancels the pressure difference at different positions of the contact surface between the recess and the convex part through deformation.

7. The composite material propeller blade RTM mold structure according to claim 6, characterized in that, The buffer substrate has a honeycomb structure, with multiple honeycomb chambers formed inside, each of which is independent of the others.

8. The composite material propeller blade RTM mold structure according to claim 7, characterized in that, The honeycomb cavity is filled with a flowing medium, which is used to absorb the impact force during the mold closing process.

9. The composite material propeller blade RTM mold structure according to claim 8, characterized in that, The flowing medium is high-viscosity silicone oil.

10. The composite material propeller blade RTM mold structure according to claim 9, characterized in that, The opening of the reserved groove is covered with a thin plate, which is in close contact with the upper surface of the buffer substrate.

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