A resin transfer moulding cure tool for a composite material blade

Abstract

The application provides a resin transfer molding curing mold for composite material blades, and belongs to the technical field of aero-engines. Specifically, the mold comprises an upper cover and a lower cover. Upper molding areas and lower molding areas are respectively arranged on opposite sides of the upper cover and the lower cover. The upper molding areas and the lower molding areas form a molding cavity after the upper cover and the lower cover are butted. The lower cover is provided with an inlet and an outlet which are respectively arranged on opposite sides of the lower cover and communicate with the lower molding areas. The upper cover is provided with a plurality of mounting holes which penetrate into the upper molding areas. An adjusting piston which moves in a vertical direction and slides in the mounting holes is arranged in the mounting holes. Dynamic sealing is arranged between the adjusting piston and the mounting holes. A sensor is arranged at the bottom of the mounting holes. The sensor is used for detecting the pressure and temperature of the mounting hole position. Through the processing scheme, efficient resin filling and high-quality molding of the composite material blades are realized.

Description

Technical Field

[0001] This application relates to the field of aero-engines, and in particular to a resin transfer molding curing mold for composite blades. Background Technology

[0002] Composite materials are widely used in aerospace fields, including fan blades and wings, due to their advantages such as low density and high specific strength. To further improve the impact resistance of pure composite material structures, a new type of aerospace composite material based on metal skeleton support has been developed. Its preform structure has a more complex internal structure, and the difficulty of resin curing and molding is further increased.

[0003] The flow of resin within composite blades is highly complex. After the fibers are woven onto the blade surface, the fiber density and orientation vary at different locations. Higher fiber volume content results in greater flow resistance, while lower fiber volume content leads to lower flow resistance. These differences in flow resistance interfere with the speed and direction of resin flow. In the resin transfer molding (RTM) process for composite blades, it is desirable for the resin to flow sufficiently through every part of the fiber weave. This requires not only a rational design method but also a well-designed flow channel structure and the installation of appropriate adjustment devices to effectively prevent localized resin accumulation.

[0004] Furthermore, in composite structures based on metal skeletons, resin flow at the pores of the metal skeleton is complex, making direct flow to ensure filling extremely difficult and posing a risk of incomplete filling and degraded quality performance. Therefore, it is necessary to rationally design relevant molding dies and process methods to avoid extreme situations.

[0005] Patent EP3077175A4 discloses a rapid circulation method for resin transfer molding. The staggered arrangement of resin injection ports can promote rapid filling of the mold cavity, and controlling the combination and sequence of injection ports can promote resin penetration into the fibers. However, it lacks detection means and methods, cannot reflect the resin flow in the mold in real time, and the resin flow in the mold often differs significantly from the design and the final actual situation.

[0006] Patent CN217671214U discloses an RTM mold for preparing 3D woven bulletproof composite materials with ultra-high fiber content. The mold includes a piston block, a limiting block, and other structural components. The piston block is embedded in the frame and can adjust the mold cavity size by moving up and down, thus designing a mold system with adjustable mold cavity size. However, it lacks the means for precise measurement and local adjustment of key parts.

[0007] Patent CN111169044A discloses a composite material blade RTM molding die and method. Targeting high-toughness liquid molding resin, it addresses the issue of excessive temperature fluctuations during long-distance flow by incorporating a flow-retarding zone on the molding die that communicates with the resin inlet. This effectively solves the problem of regional resin infeed control in traditional RTM processes and reduces edge effects present in conventional RTM. However, it lacks precise measurement and local adjustment methods for critical areas.

[0008] Existing devices and methods cannot solve the problem of accurately monitoring the complex resin flow in large-sized, metal-framed composite braided structures, and are prone to poor molding quality due to uneven resin temperature and flow distribution. Summary of the Invention

[0009] In view of this, this application provides a resin transfer molding curing mold for composite blades, which solves the problems in the prior art and achieves efficient resin filling and high-quality molding of composite blades.

[0010] The resin transfer molding and curing mold for composite material blades provided in this application adopts the following technical solution:

[0011] A resin transfer molding curing mold for composite blades includes an upper cover and a lower cover. The upper and lower covers have an upper molding area and a lower molding area on their opposite sides, respectively. When the upper and lower covers are joined, the upper and lower molding areas form a cavity. The lower cover has an inlet and an outlet on opposite sides, respectively, connecting to the lower molding area. The top surface of the upper cover has multiple mounting holes extending into the upper molding area. An adjusting piston that moves vertically and slides within each mounting hole is installed in the mounting hole. A dynamic seal is provided between the adjusting piston and the mounting hole. A sensor is installed at the bottom of each mounting hole to detect pressure and temperature at the mounting hole location.

[0012] Optionally, the adjusting piston has a vertical perforation inside, and a perforation seal is provided inside the perforation. The sensor is installed at the bottom of the perforation seal, and the sensor lead extends through the perforation seal and out of the top cover. The perforation seal and the adjusting piston are sealed together.

[0013] Optionally, the mounting hole includes a small-diameter section and a large-diameter section distributed sequentially from top to bottom. The upper part of the adjusting piston is fitted with the inner wall of the small-diameter section, and the lower part of the adjusting piston is provided with an annular protrusion protruding into the inner wall of the large-diameter section. A sealing ring is embedded in the outer periphery of the annular protrusion. The sealing ring seals the gap between the annular protrusion and the large-diameter section, and the sealing ring slides up and down along the inner wall of the large-diameter section with the adjusting piston.

[0014] Optionally, a locking ring is detachably connected to the bottom of the mounting hole, the top wall of the locking ring abuts against the bottom of the adjusting piston, and the sensor is located in the inner ring of the locking ring.

[0015] Optionally, the mold may further include the metal skeleton and composite preform placed in the cavity, wherein the metal skeleton and composite preform are woven together into a single piece.

[0016] Optionally, the position of the mounting hole is determined by the following steps:

[0017] We conducted porosity and permeability measurements of typical sample preforms based on specific preform weaving processes, specific fibers, and resins to establish basic simulation parameters, construct a geometric model for resin flow field calculation, and carry out RTM resin flow simulation of typical sample preforms.

[0018] Typical RTM resin curing tests were conducted to obtain the internal defect distribution of the actual cured typical RTM resin sample through non-destructive testing, and the resin flow simulation method and model were calibrated.

[0019] By iterating the above steps repeatedly, a high-precision resin flow simulation calculation method can be obtained.

[0020] A geometric model of the composite preform for composite blades is established, a computational flow domain is established to simulate resin flow, the resin flow process during the RTM process is obtained, several key inspection locations affecting the molding quality of composite blades are identified, and mounting holes are set at several key inspection locations.

[0021] Optionally, during the resin transfer molding process in the mold, the pressure and temperature of different mounting hole areas change over time. Multiple key moments are selected for each mounting hole, and preset values ​​of temperature and pressure to be reached at each key moment are determined. The key moments are different for different mounting hole areas.

[0022] The temperature and pressure values ​​of each mounting hole area are determined at multiple critical moments. If the temperature and pressure at the mounting hole location are lower than a predetermined preset value at a critical moment, the adjusting piston in the corresponding mounting hole is slid upward to attract resin into the mounting hole. Then, the adjusting piston is pressed downward to squeeze the resin into the composite preform, thereby destroying the bubble structure in the dry area of ​​the mounting hole area. The bubbles are squeezed and broken up, and the dispersed bubbles flow out of the molding area of ​​the mold with the resin. The steps of sliding the adjusting piston up and down are repeated until the temperature and pressure of the corresponding mounting hole area reach the preset value.

[0023] In summary, this application includes the following beneficial technical effects:

[0024] The sensor in this application transmits the detected data to an external monitoring device via an external wire. By analyzing the corresponding pressure and temperature data, the flow distribution of the resin inside is determined, and the resin filling distribution effect at the sensor location is analyzed and evaluated. If there is no impregnation, the piston is adjusted up and down to achieve local pressure changes, thereby improving the resin impregnation effect in key areas and ultimately improving the molding quality of composite material components. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic cross-sectional view of the resin transfer molding curing mold for composite blades;

[0027] Figure 2 This is a schematic diagram of the structure of the cover of this application;

[0028] Figure 3 This is a schematic diagram of the structure of the cover of this application;

[0029] Figure 4 This is a schematic diagram of the overall structure of the resin transfer molding and curing mold for the composite material blades of this application.

[0030] Figure 5 for Figure 4 A magnified structural diagram of part A in the middle;

[0031] Figure 6 This is a schematic diagram illustrating the process of using a resin transfer molding and curing mold for the composite material blades in this application.

[0032] Explanation of reference numerals in the attached drawings: 1. Top cover; 11. Mounting hole; 12. Upper forming area; 2. Metal frame; 3. Composite preform; 4. Bottom cover; 41. Inlet; 42. Lower forming area; 43. Outlet; 5. Sensor; 51. External wire; 52. Through-chamber seal; 53. Adjusting piston; 54. Sealing ring; 55. Locking ring. Detailed Implementation

[0033] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0034] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0036] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0037] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0038] This application provides a resin transfer molding curing mold for composite material blades.

[0039] like Figures 1-5As shown, a resin transfer molding (RTM) curing mold for composite blades includes an upper cover 1 and a lower cover 4. Upper molding area 12 and lower molding area 42 are respectively provided on opposite sides of the upper cover 1 and lower cover 4. After the upper cover 1 and lower cover 4 are joined, the upper molding area 12 and lower molding area 42 form a cavity, which serves as a closed space for resin RTM molding of the composite blade. The lower cover 4 has an inlet 41 and an outlet 43 on opposite sides, respectively, connecting to the lower molding area 42. The resin inlet 41 and resin outlet 43 are used for resin inflow and outflow during the molding process. The number of resin inlets 41 and resin outlets 43 can be optimized according to structural requirements. The top surface of the upper cover 1 has multiple mounting holes 11 extending into the upper molding area 12. An adjusting piston 53, which moves vertically and slides within the mounting hole 11, is provided within each mounting hole 11. A dynamic seal is provided between the adjusting piston 53 and the mounting hole 11. A sensor 5 is provided at the bottom of each mounting hole 11 for detecting pressure and temperature at the mounting hole 11 position. The number and location of the mounting holes 11 are determined by a combination of the required location and geometric structure.

[0040] The mold also includes a metal skeleton 2 and a composite preform 3 placed in the cavity. The metal skeleton 2 and the composite preform 3 are woven together as a single piece, and the resin impregnation and curing process of the structure composed of the metal skeleton 2 and the composite preform 3 is completed in the cavity. The composite preform 3 is woven from carbon fiber and is tightly fixed to the metal skeleton 2 by the cross-winding of carbon fibers. Before curing, it is a dry fiber-metal mixed woven structure. After resin curing, it forms the final composite blade. Because the combined structure includes carbon fiber and metal skeleton 2, the viscosity of the resin on the surfaces of these two materials is different, which makes the flow more complex and may cause local resin non-penetration in the composite preform 3, resulting in manufacturing defects.

[0041] By acquiring the detection data of the deployed sensors 5 to accurately monitor the resin flow inside the mold and predict the resin filling of the composite preform 3, the pressure distribution of the resin is locally adjusted by detecting the position of the adjusting piston 53 in the adjusting mechanism, thereby achieving efficient resin filling and high-quality molding of composite blades.

[0042] Sensor 5 transmits the detected data to an external monitoring device via an external wire 51. By analyzing the corresponding pressure and temperature data, the flow distribution of resin inside is determined, and the resin filling distribution effect at the location of sensor 5 is analyzed and evaluated. If there is no impregnation, the piston 53 is adjusted up and down to achieve local pressure changes, thereby improving the resin impregnation effect in key areas and ultimately improving the molding quality of composite material components.

[0043] In one embodiment, during actual operation, sensor 5 is tightly attached to the composite preform 3 to monitor physical parameters at key detection locations during resin molding. When resin does not flow through a location or is not fully impregnated, the temperature and pressure at that location are low, requiring adjustment of the local pressure using adjusting piston 53. When adjusting piston 53 is moved upward, a low-pressure area is formed locally, attracting resin into the mounting hole 11. Then, adjusting piston 53 is pressed downward, forcing the resin back into the composite preform 3. This adjustment can break the bubble structure in the dry area where the resin is not fully impregnated, squeezing large bubbles into smaller bubbles that flow out of the molding area of ​​the mold with the resin flow. At this time, the temperature and pressure of sensor 5 significantly rise to the predetermined value. When the resin fully impregnates the composite preform 3, the temperature and pressure significantly rise to the preset value, indicating that molding is successful at that location, and no local pressure adjustment using adjusting piston 53 is required.

[0044] In the product formation process provided in this embodiment, since there is no metal skeleton 2 and composite preform 3 inside the mounting hole 11, the space inside the mounting hole 11 should be filled with resin first during the initial resin flow. This prevents the introduction of new air bubbles when breaking them up. Additionally, the formed product will have protrusions on the surface corresponding to the mounting hole 11. After the product is manufactured, these protrusions can be removed by grinding, or the depth of the upper molding area 12 can be increased during the design phase, reserving a sacrificial layer in the cavity that can be formed on the upper surface of the product. Finally, the sacrificial layer with protrusions can be removed to ensure that the prepared product meets the design requirements.

[0045] like Figure 5 As shown, the adjusting piston 53 has a vertically oriented perforation inside, and a perforation seal 52 is provided inside the perforation. The sensor 5 is installed at the bottom of the perforation seal 52, and the lead wire of the sensor 5 passes through the perforation seal 52 and extends out of the upper cover 1. The top of the perforation seal 52 is provided with an external wire 51 for connecting the lead wire of the sensor 5, realizing communication between the sensor 5 inside the mounting hole 11 and the external control system. The perforation seal 52 and the adjusting piston 53 are sealed together. The perforation seal 52 can realize the transmission of sensor 5 data to the outside while ensuring internal sealing performance.

[0046] like Figure 5As shown, the mounting hole 11 includes a small-diameter section and a large-diameter section distributed sequentially from top to bottom. The upper part of the adjusting piston 53 is fitted with the inner wall of the small-diameter section, and the lower part of the adjusting piston 53 has an annular protrusion protruding into the inner wall of the large-diameter section. A sealing ring 54 is embedded in the outer periphery of the annular protrusion. The sealing ring 54 seals the gap between the annular protrusion and the large-diameter section, and the sealing ring 54 slides up and down along the inner wall of the large-diameter section with the adjusting piston 53. A locking ring 55 is installed and fixed in the mounting hole 11 by means of threads or other connections to constrain the movement range of the adjusting piston 53 and prevent the adjusting piston 53 from dislodging from the mounting hole 11 of the mold cover 1. The annular protrusion of the adjusting piston 53 and the sealing ring 54 can form a sliding pair while ensuring sealing performance, and can ensure the pressure maintained in the molding area.

[0047] like Figure 6 As shown in the embodiment of this application, the operating principle of a resin transfer molding curing mold for composite material blades is provided. Figure 6 In the diagram, the X direction represents the resin flow direction. During the resin flow within the area of ​​the metal skeleton 2 and the composite preform 3, the flow becomes complex due to the different viscosity coefficients of the resin, the metal surface, and the composite material (carbon fiber) surface. Large unwetted areas and large air bubbles easily appear at key detection locations on the composite blade. The presence of these large air bubbles affects further resin wetting, ultimately impacting the molding quality of the composite blade. At this point, the sensor 5 can identify a significant difference in flow pressure and actual temperature at that location; that is, the measured temperature is significantly lower than expected. This indicates that difficult-to-eliminate air bubbles have formed at this point during the molding process. By adjusting the adjusting piston 53 along the Y direction, the adjusting piston 53 draws the air bubbles and some resin into the mounting hole 11. Then, adjusting the adjusting piston 53 along the Z direction breaks the large air bubbles into smaller ones, allowing them to flow out of the molding area along the X direction of resin flow, ultimately improving the molding quality of the composite blade.

[0048] This application also provides steps for determining the location of the mounting hole 11.

[0049] The position of mounting hole 11 is determined by the following steps:

[0050] We conducted tests on the porosity and permeability of typical sample preforms based on specific preform weaving processes, specific fibers, and resins to establish basic simulation parameters, construct a geometric model for resin flow field calculations, and carry out RTM resin flow simulations on typical sample preforms.

[0051] Typical RTM resin curing tests were conducted to obtain the internal defect distribution of the actual cured typical RTM resin sample through non-destructive testing, and the resin flow simulation method and model were calibrated.

[0052] By iterating the above steps repeatedly, a high-precision resin flow simulation calculation method can be obtained.

[0053] A geometric model of the composite preform 3 for composite blades was established, a computational flow domain was established to simulate resin flow, the resin flow process during the RTM process was obtained, and several key inspection locations affecting the molding quality of composite blades were identified. Mounting holes 11 were set at several key inspection locations.

[0054] Preliminary resin simulation was used to determine the key detection areas and locations of the composite blades during the RTM curing process, and mounting holes 11 were machined on the mold cover 1.

[0055] Furthermore, during the resin transfer molding process in the mold, the pressure and temperature of different mounting hole 11 areas change over time. Multiple key moments are selected for each mounting hole 11, and preset values ​​of temperature and pressure to be reached at each key moment are determined. The key moments are different for different mounting hole 11 areas.

[0056] The temperature and pressure values ​​of each mounting hole 11 area are determined at multiple critical moments. If the temperature and pressure at the mounting hole 11 location are lower than a predetermined preset value at a critical moment, the adjusting piston 53 in the corresponding mounting hole 11 is slid upward to attract resin into the mounting hole 11. Then, the adjusting piston 53 is pressed downward to squeeze the resin into the composite preform 3, breaking the bubble structure in the dry area of ​​the mounting hole 11 area. The bubbles are squeezed and broken up, and the dispersed bubbles flow out of the molding area of ​​the mold with the resin. The steps of sliding the adjusting piston 53 up and down are repeated until the temperature and pressure of the corresponding mounting hole 11 area reach the preset value. The above description is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A resin transfer molding and curing mold for composite material blades, characterized in that, The device includes an upper cover and a lower cover. The upper cover and the lower cover have upper molding areas and lower molding areas on their opposite sides, respectively. After the upper cover and the lower cover are joined together, the upper molding areas and the lower molding areas form a cavity. The lower cover has an inlet and an outlet on its opposite sides that connect to the lower molding area. The top surface of the upper cover has multiple mounting holes that extend into the upper molding area. An adjusting piston that moves vertically and slides within the mounting hole is installed in each mounting hole. A dynamic seal is provided between the adjusting piston and the mounting hole. A sensor is installed at the bottom of the mounting hole to detect the pressure and temperature at the mounting hole position. The mold also includes a metal skeleton and a composite preform placed in the cavity, wherein the metal skeleton and the composite preform are woven together into a single piece; The location of the mounting hole is determined by the following steps: We conducted porosity and permeability measurements on typical samples based on specific preform weaving processes, specific fibers, and resins to establish basic simulation parameters, construct a geometric model for resin flow field calculations, and carry out RTM resin flow simulations on typical samples. Typical RTM resin curing tests were conducted to obtain the internal defect distribution of the actual cured RTM resin sample through non-destructive testing, and the resin flow simulation method and model were calibrated. By iterating the above steps repeatedly, a high-precision resin flow simulation calculation method can be obtained. Establish a geometric model of the composite preform for composite blades, establish a computational flow domain to simulate resin flow, obtain the resin flow process during the RTM process, identify multiple key inspection locations that affect the molding quality of composite blades, and set mounting holes at multiple key inspection locations. During the resin transfer molding process in the mold, the pressure and temperature of different mounting hole areas change over time. Multiple key moments are selected for each mounting hole, and the preset values ​​of temperature and pressure to be reached at each key moment are determined. The key moments are different for different mounting hole areas. The temperature and pressure values ​​of each mounting hole area are determined at multiple critical moments. If the temperature and pressure at the mounting hole location are lower than a predetermined preset value at a critical moment, the adjusting piston in the corresponding mounting hole is slid upward to attract resin into the mounting hole. Then, the adjusting piston is pressed downward to squeeze the resin into the composite preform, thereby destroying the bubble structure in the dry area of ​​the mounting hole area and crushing the bubbles. The dispersed bubbles flow out of the molding area of ​​the mold with the resin. The steps of sliding the adjusting piston up and down are repeated until the temperature and pressure of the corresponding mounting hole area reach the preset value.

2. The resin transfer molding and curing mold for composite material blades according to claim 1, characterized in that, The adjusting piston has a vertical perforation inside, and a perforation seal is provided inside the perforation. The sensor is installed at the bottom of the perforation seal, and the sensor lead extends through the perforation seal and out of the top cover. The perforation seal and the adjusting piston are sealed together.

3. The resin transfer molding and curing mold for composite material blades according to claim 1, characterized in that, The mounting hole includes a small diameter section and a large diameter section distributed sequentially from top to bottom. The upper part of the adjusting piston is fitted with the inner wall of the small diameter section, and the lower part of the adjusting piston is provided with an annular protrusion protruding into the inner wall of the large diameter section. A sealing ring is embedded in the outer periphery of the annular protrusion. The sealing ring seals the gap between the annular protrusion and the large diameter section, and the sealing ring slides up and down along the inner wall of the large diameter section with the adjusting piston.

4. The resin transfer molding and curing mold for composite material blades according to claim 1, characterized in that, A locking ring is detachably connected to the bottom of the mounting hole. The top wall of the locking ring abuts against the bottom of the adjusting piston, and the sensor is located in the inner ring of the locking ring.

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