Zoned independent pressure core device and method for composite parts

Abstract

The application relates to a partitioned independent pressure regulating mandrel device for a composite part and a forming method, the mandrel device comprising a metal mandrel, a flexible pressurized cavity, a soft mold layer and a pressure control assembly, an outer forming surface of the metal mandrel is profile-matched with a cavity contour of the composite part, the flexible pressurized cavity is arranged on the outer forming surface of the metal mandrel in a sleeving mode, a plurality of mutually isolated pressure cavities are formed in the flexible pressurized cavity, the pressure cavities can be independently regulated, and the pressure cavities are arranged according to the geometric characteristics of the composite part to be formed in a corresponding partitioned mode, the soft mold layer is arranged on the outer forming surface of the flexible pressurized cavity in a sleeving mode, the pressure control assembly comprises a controller, a plurality of pressure regulating valves and a plurality of pressure sensors, each pressure regulating valve and each pressure sensor are electrically connected with the controller, the application can independently perform pressure detection and regulation on different regions of a complex surface, thereby the defects in different regions can be adjusted in a partitioned mode, and the quality of component forming is improved.

Description

Technical Field

[0001] This application relates to the field of composite material molding tooling technology, and in particular, to a partitioned independent pressure regulating mandrel device and molding method for composite material parts. Background Technology

[0002] In the autoclave curing process of composite materials, the mandrel system is the core tooling that ensures the molding accuracy and quality of the components. Its core function is to provide stable support for the prepreg surface throughout the entire curing process and to transmit uniform and effective molding pressure to each molding area of ​​the component, ultimately ensuring the external accuracy and internal molding quality of the composite parts. Currently, the core mold technologies commonly used in the field of composite material autoclave molding are mainly divided into three categories: pure metal hard mold technology, pure silicone rubber soft mold technology, and soft-hard combination mold technology, as detailed below: 1. Pure metal hard molding technology This technology uses metal substrates such as aluminum alloy and Invar steel, which are precision machined into integral or segmented core mold structures. Typical applications include the left and right half mold mating mold structure disclosed by Guanglian Aviation (CN114588882A) and the segmented mold and core mold combination structure disclosed by Harbin FRP Research Institute (CN116549399A). These metal core molds rely on the high rigidity of the metal material itself to maintain the accuracy of the component's surface shape. The forming pressure is entirely dependent on the global environmental pressure of the autoclave for passive pressure application, resulting in strong structural stability, but the pressure supply method is singular.

[0003] 2. Pure silicone rubber soft mold technology This technology uses high-temperature resistant silicone rubber to cast and mold the core mold, utilizing the volume expansion characteristics of silicone rubber after being heated to provide molding pressure for the prepreg. This type of soft mold has good surface adaptability and can meet the molding requirements of complex internal cavity components. However, the molding pressure relies entirely on the thermal expansion effect of the material, and cannot be actively controlled, resulting in poor pressure output accuracy and controllability.

[0004] 3. Hardware and soft combination mold technology Some existing molding solutions employ a combination of rigid and flexible core mold structures with a metal skeleton encased in a silicone rubber layer, combining the rigidity of the metal structure with the surface adaptability of the silicone rubber. However, this type of combined mold only fixes the metal skeleton and the silicone rubber layer through bonding and simple nesting. The structure is simple and lacks pressure monitoring and active pressure control mechanisms, making it impossible to achieve real-time monitoring and precise adjustment of molding pressure.

[0005] Based on the existing core film technology, there are generally technical defects in the mass production of composite parts with complex cross-sections and complex shapes, such as poor adaptability of molding pressure, inability to monitor the condition, and lack of basis for process optimization, as detailed below: 1. The molding pressure of complex surfaces cannot be differentiated and controlled, leading to a high incidence of molding defects. The autoclave provides a uniform pressure field throughout the entire surface, while the molding pressure requirements for different geometric regions of complex composite parts vary significantly. Areas such as the radius corners and rib roots, characterized by fiber accumulation and thicker walls, require higher molding pressures to promote resin flow and thoroughly expel interlayer gases. Conversely, excessive pressure on straight sections and flat surfaces can easily cause fiber buckling and excessive resin loss. Existing mandrel systems can only provide a single, uniform molding pressure, failing to provide differentiated pressure for different regions of complex surfaces. This results in bridging and porosity defects at the radius corners and rib roots, and fiber buckling and resin loss defects in flat areas, leading to a low overall yield rate.

[0006] 2. The actual pressure state during the molding process is unknown, and there is no basis for tracing the source of quality defects. The existing mandrel system cannot directly detect the actual molding pressure at the contact surface between the prepreg and the mandrel. The ambient pressure output from the autoclave must be transmitted and attenuated layer by layer through multiple auxiliary tooling materials such as vacuum bags, breathable felts, and isolation membranes before it can act on the surface of the prepreg. Moreover, the complexity of different component shapes varies, and the degree of pressure attenuation varies significantly. Process personnel cannot accurately obtain the real-time actual pressure values ​​of each molding area. Subsequent component quality defect analysis and problem tracing lack real pressure data support, making it difficult to accurately locate the cause of molding failures.

[0007] 3. Lack of data support for molding process optimization leads to high trial production costs and long cycles. Current mandrel pressure supply is passive, relying on autoclave environmental pressure or the thermal expansion effect of silicone rubber. The pressure status in each area during the molding process cannot be sensed or actively adjusted. Process optimization relies entirely on operator experience, iteratively adjusting process parameters through repeated trials and mold modifications. There is no systematic, data-driven mechanism for accumulating process parameters, resulting in low optimization efficiency and significantly increased component trial production costs and cycles. This fails to meet the demands for large-scale, high-quality production of high-precision, complex composite parts. Summary of the Invention

[0008] The technical problem to be solved by this application is to provide a zoned independent pressure regulating mandrel device and molding method for composite material parts. This application can perform real-time and independent pressure detection and control on different areas of complex surfaces, thereby enabling zoned adjustment of defects in different areas and improving the quality of component molding.

[0009] To address the aforementioned technical problems, according to one aspect of this application, a partitioned independent pressure-regulating mandrel device for composite material parts is provided, comprising: a metal mandrel, the outer forming surface of which conforms to the cavity contour of the composite material part; a flexible pressure chamber, which covers the outer forming surface of the metal mandrel, and forms multiple mutually isolated pressure chambers inside the flexible pressure chamber, each pressure chamber being independently adjustable in pressure, and each pressure chamber being partitioned according to the geometric characteristics of the composite material part to be molded; a soft mold layer, which covers the outer forming surface of the flexible pressure chamber; and a pressure control component, comprising: a controller, multiple pressure regulating valves, and multiple pressure sensors, each pressure regulating valve and each pressure sensor being electrically connected to the controller, wherein each pressure chamber is equipped with at least one pressure sensor and one pressure regulating valve, the controller receiving the measurement signals of the pressure sensors corresponding to each pressure chamber in real time and calculating the average pressure value, comparing the average pressure value with the corresponding target pressure value, thereby controlling the corresponding pressure regulating valve in real time to adjust the internal pressure of the corresponding pressure chamber.

[0010] According to an embodiment of this application, the partitioned independent pressure regulating mandrel device for composite material parts further includes a support layer sandwiched between the flexible pressure chamber and the metal mandrel, for buffering the thermal expansion difference between the metal mandrel and the flexible pressure chamber, and for providing uniform support for the flexible pressure chamber.

[0011] According to embodiments of this application, the composite material part includes at least one of a high-pressure zone, a pressure equalization zone, a pulsed pressure boosting zone, and a gradient pressure zone. The same composite material part to be molded may contain multiple zones of the same type. The high-pressure zone is the area corresponding to the open-angle region or the root position of the ribs in the composite material part. The pressure chamber corresponding to the high-pressure zone applies a molding pressure greater than that of the autoclave to the high-pressure zone. The pressure equalization zone is the area corresponding to the straight segment or web region of the composite material part. The pressure chamber corresponding to the pressure equalization zone applies a molding pressure equal to that of the autoclave to the pressure equalization zone. The pulsed pressure boosting zone is the area corresponding to the closed-angle region of the composite material part. The pressure chamber corresponding to the pulsed pressure boosting zone applies a molding pressure that increases pulse by pulse to the pulsed pressure boosting zone. The gradient pressure zone is the area corresponding to the thickness gradient transition region of the composite material part. Multiple pressure chambers correspond to the gradient pressure zone, and these multiple pressure chambers apply gradient pressure to the gradient pressure zone.

[0012] According to an embodiment of this application, a conformal heat exchange channel is arranged inside the metal mandrel. The wall thickness of the metal mandrel is not less than 10 mm. Each pressure chamber is equipped with an independent gas source interface and a gas pipeline. The gas pipeline includes a first gas pipe and a second gas pipe. The first gas pipe and the second gas pipe are connected. The first gas pipe passes through the side wall of the metal mandrel and is connected to the gas source interface. The second gas pipe is located inside the conformal heat exchange channel and is arranged along the extension direction of the conformal heat exchange channel. The second gas pipe is connected to an external gas source.

[0013] According to embodiments of this application, the flexible pressurized cavity is an airbag-type pressure cavity or a hydraulic cavity.

[0014] According to an embodiment of this application, a plurality of pressure sensors are configured in the same pressure chamber. The plurality of pressure sensors are located inside the pressure chamber or between the pressure chamber and the soft mold layer. The plurality of pressure sensors are respectively arranged in the central region and the edge region of the pressure chamber.

[0015] According to another aspect of this application, a method for molding a composite material part is provided, comprising the following steps: Step S1, obtaining the target pressure of each pressure chamber during molding through experimental testing: The above-mentioned partitioned independent pressure regulating mandrel device for composite material parts is used to form composite material test workpieces. All pressure chambers are set with a uniform initial pressure, and the formed composite material test workpieces are subjected to defect detection, and the defect location and type are recorded. Adjust the target pressure setting value of the pressure chamber corresponding to the defect location according to the defect type, re-form the composite material test workpiece, record the pressure, defect location and type of each pressure chamber after adjustment, analyze the defect improvement effect, and repeatedly execute the parameter adjustment, component forming, data recording and effect analysis process until the quality of the formed composite material test workpiece meets the standard. Then, store the pressure value corresponding to each pressure chamber and use it as the target pressure of each pressure chamber when forming the formal composite material component. In step S2, the partitioned independent pressure regulating mandrel device for composite material parts is used to form the formal composite material component according to the target pressure of each pressure chamber obtained in step S1 and the same forming steps as the composite material test workpiece in step S1.

[0016] According to an embodiment of this application, in step S1, the method for adjusting the target pressure setting value of the pressure chamber corresponding to the defect location based on the defect type is as follows: if the defect type is a pore or bridging, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by stepwise increasing; if the defect type is fiber buckling or resin loss, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by stepwise decreasing.

[0017] According to an embodiment of this application, the molding step includes: pre-inspection of the partitioned independent pressure regulating mandrel device for composite material parts; prepreg laying; vacuum bag sealing and vacuum leak detection; controlling the autoclave to heat up to a first temperature, while controlling each pressure regulating valve to increase the pressure of each pressure chamber to 40%-60% of the corresponding target pressure; controlling the autoclave to continue heating to a second temperature and pressurizing to the first pressure, while controlling each pressure regulating valve to pressurize each pressure chamber to the corresponding target pressure, and performing closed-loop control, the controller receives the pressure transmitter acquisition signal corresponding to each pressure chamber and calculates the average pressure value, compares the average pressure value with the corresponding target pressure value, and if the average pressure value is... When the absolute value of the difference between the corresponding target pressure values ​​does not exceed a set threshold, the pressure in the pressure chamber remains unchanged. If the absolute value of the difference between the average pressure value and the corresponding target pressure value is greater than the set threshold, the controller controls the pressure regulating valve to adjust the internal pressure of the corresponding pressure chamber. The controller controls the autoclave to continue heating to the third temperature, pressurizing to the second pressure, and then maintaining the temperature and pressure. At the same time, the controller controls the pressure chamber corresponding to the pulse pressurization zone to apply a pulse-increasing molding pressure to the closed-angle region of the composite material part. The initial pressure loading value is the target pressure corresponding to the pressure chamber. All other pressure chambers maintain pressure and are subject to closed-loop control. When the dielectric sensor monitors that the resin curing degree is ≥90%, cooling and demolding are performed.

[0018] According to an embodiment of this application, the controller includes a storage module. The storage module establishes a composite material part process database based on the stored types of composite material parts to be molded and the target pressures of each pressure chamber. When molding composite material parts, the target pressures corresponding to each pressure chamber are obtained from the composite material part process database according to the type of composite material part to be molded and the material.

[0019] According to an embodiment of this application, the controller has a built-in machine learning model. The machine learning model predicts the pressure value of each pressure chamber of the composite material part to be formed based on the composite material part process database and the geometric features and material of the composite material part to be formed, and uses it as the initial pressure value of each pressure chamber of the composite material test workpiece.

[0020] Compared with the prior art, the beneficial effects of this application are as follows: This application discloses a zoned, independently pressure-adjustable mandrel device for composite material parts. The flexible pressure chamber between the metal mandrel and the soft mold layer comprises multiple isolated pressure chambers. Each pressure chamber is zoned according to the geometric characteristics of the composite material part to be molded, and each pressure chamber is equipped with an independent pressure sensor, air path, and regulating valve. The controller can independently control the pressure of each pressure chamber and adjust the pressure of each chamber based on real-time feedback from the pressure sensors. Furthermore, it can analyze the causes of defects based on the defects in each zone and the pressure data during the molding process, thereby optimizing the molding process. This application enables real-time, independent pressure detection and control of different zones on complex surfaces, allowing for zoned adjustment of defects in different areas, thus improving the quality of the molded component. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a partitioned independent pressure regulating mandrel device for composite material parts according to an embodiment of this application.

[0022] Figure 2 This is a control logic diagram of a partitioned independent pressure regulating mandrel device for composite material parts according to an embodiment of this application.

[0023] Figure 3 This is a schematic diagram of a molding method for a composite material part according to another embodiment of this application.

[0024] Figure 4 This is a schematic diagram of the molding process according to another embodiment of this application.

[0025] Figure label: A partitioned independent pressure regulating mandrel device 100 for composite material parts, a metal mandrel 10, a conformal heat exchange channel 11, a flexible pressurizing cavity 20, a pressure chamber 21, a first air pipe 211, a soft mold layer 30, a controller 41, a pressure regulating valve 42, a pressure sensor 43, and a composite material part 200. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this application pertains. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects. Unless otherwise specified, the term "connection" as used herein can refer to a direct connection or an indirect connection, i.e., a connection through an intermediate object.

[0027] The terms "first," "second," and similar words used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0028] The partitioned independent pressure regulating mandrel device for composite material parts of this application is applicable to the molding and manufacturing of composite material parts with complex cross-sectional features of cavities (such as hat-shaped stiffened wall panels, Ω-shaped stringers, multi-cavity box-shaped parts, etc.) in the fields of aviation, aerospace, and rail transportation.

[0029] Hereinafter, embodiments of this application will be described with reference to the accompanying drawings.

[0030] Figure 1 This is a schematic diagram of a partitioned independent pressure regulating mandrel device for composite material parts according to an embodiment of this application.

[0031] See Figure 1 According to one embodiment of this application, a partitioned independent pressure regulating mandrel device 100 for composite material parts includes: a metal mandrel 10, a flexible pressure chamber 20, a soft mold layer 30, and a pressure control component.

[0032] The outer forming surface of the metal mandrel 10 is matched with the cavity contour of the composite material part 200.

[0033] Specifically, the metal mandrel 10 can be a fully enclosed metal mandrel, i.e., as shown in the figure. Figure 1 As shown, the forming surface of the metal mandrel 10 completely fits the entire contour surface of the cavity constituting the composite material part 200. When the composite material part is an Ω-shaped stringer, the metal mandrel 10 can also be a partially covered metal mandrel. The outer forming surface of the metal mandrel only covers the arched surface and corner area of ​​the inner cavity of the component, and does not provide internal pressure to the side flanges. The flanges are only compacted on one side by the environmental pressure of the external autoclave.

[0034] In some embodiments, the metal mandrel 10 is provided with conformal heat exchange channels 11, and the wall thickness of the metal mandrel 10 is not less than 10 mm. During the molding process, by circulating a heat exchange medium (heat transfer oil or cooling water) into the conformal heat exchange channels 11, synchronous temperature control can be achieved on the inner side along the molding surface of the component, reducing the temperature difference between the inside and outside of the composite material part in the thickness direction, optimizing the uniformity of the molding temperature field, reducing residual stress after curing, and reducing warping deformation of the component; at the same time, it stabilizes the working temperature of the outer flexible pressure chamber, ensures the accuracy of zoned pressure transmission, avoids problems such as uneven curing degree and unbalanced resin distribution in closed-angle areas and thickness transition areas, and improves the molding quality and shape accuracy of the composite material part.

[0035] Specifically, the metal mandrel 10 is made of high-strength aluminum alloy (such as 7075-T6) or Invar steel, and is precision machined to obtain a profile that matches the cavity contour of the composite material part 200.

[0036] The flexible pressurizing cavity 20 is covered and set on the outer forming surface of the metal mandrel 10. Multiple mutually isolated pressure chambers 21 are formed inside the flexible pressurizing cavity 20. Each pressure chamber 21 can independently adjust the pressure. Each pressure chamber is arranged in corresponding zones according to the geometric characteristics of the composite material part to be formed.

[0037] In some embodiments, the flexible pressurization chamber 20 is an airbag-type pressure chamber, and the pressure of the pressure chamber 21 is adjusted by filling the pressure chamber 21 with gas.

[0038] In some embodiments, the flexible pressurized chamber 20 is a hydraulic chamber, and the pressure of the pressure chamber 21 is regulated by introducing a liquid, such as hydraulic oil, into the pressure chamber 21. Hydraulic chambers can provide higher molding pressure and faster response times, making them suitable for high-viscosity resin systems or thick-walled components. Compared to pneumatic pressure chambers, hydraulic chambers present challenges in sealing complexity and the risk of oil leakage.

[0039] Specifically, a single partition can correspond to only one pressure chamber, or it can correspond to multiple pressure chambers. For example, when the partition area is large or the partition is a region with gradually changing thickness, one partition can correspond to multiple pressure chambers.

[0040] In some embodiments, the composite material part includes at least one of high pressure zone, equal pressure zone, pulse boosting zone and gradient pressure zone, and the same composite material part to be formed may contain multiple zones of the same type.

[0041] Specifically, the partitioning of composite parts is based on the geometric characteristics of the composite parts to be molded. For example, such as Figure 1 The composite material part 200 to be molded shown may include three equal pressure zones, two high pressure zones and two pulse boosting zones.

[0042] The high-pressure zone corresponds to the open-angle area or the root of the reinforcing ribs in the composite material part to be molded. The pressure chamber corresponding to the high-pressure zone applies a molding pressure greater than that of the autoclave. The open-angle area or the root of the reinforcing ribs has a small radius of curvature and a large fiber accumulation thickness, which easily leads to bridging and porosity. Applying a molding pressure greater than the ambient pressure of the autoclave to this area can improve the resin wetting conditions in this area and promote gas discharge, thereby reducing bridging and porosity defects.

[0043] The pressure equalization zone is the area corresponding to the straight segment or web region of the composite part to be molded. The pressure chamber corresponding to the pressure equalization zone applies the same molding pressure as the autoclave to the pressure equalization zone. Applying the same molding pressure as the autoclave ambient pressure to this area can reduce the risk of fiber buckling.

[0044] The pulsed pressurization zone corresponds to the closed-angle region of the composite material part to be molded. The pressure chamber corresponding to this zone applies pulsed increasing molding pressure. When prepreg is laid in the closed-angle region, the gas exhaust path is long, and vacuum external pressure cannot directly compact the corner. The layup is prone to detachment from the mold surface, resulting in bridging and porosity. Applying pulsed increasing molding pressure to this region can reduce bridging and porosity defects. For example, the pulsed pressure increase method is: intermittent pressurization, with a pressure increase every 3-5 minutes, and a single pressure increase of 0.15 MPa; after each pressurization, the current pressure is maintained until the next pressurization node.

[0045] The gradient pressure zone corresponds to the area where the thickness gradually changes in the composite part. Multiple pressure chambers correspond to these zones, applying gradient pressure to each zone. Applying gradient pressure to the thickness transition area allows for precise control of pressure in different thickness regions. This ensures that thicker ply areas receive sufficient pressure for thorough compaction and expulsion of interlayer gas, preventing porosity defects. Simultaneously, it prevents excessive pressure in thinner ply areas, which could lead to excessive resin loss and resin deficiency. A gently transitioning pressure load can reduce ply slippage and wrinkling at the thickness interface, balance resin content in each region, reduce residual molding stress, and ultimately improve the dimensional accuracy and internal quality consistency of the composite part.

[0046] Specifically, the surface of the metal mandrel 10 is provided with an installation interface, through which the metal mandrel 10 and the flexible pressure chamber 20 are fixed.

[0047] Specifically, the pressure chamber 21 is made of a material with a temperature greater than 200°C. More specifically, the pressure chamber 21 is made of high-temperature silicone rubber or a polyimide composite film. For example, the high-temperature silicone rubber can be methyl vinyl silicone rubber (VMQ) or fluorovinyl methyl silicone rubber (FVMQ).

[0048] In some embodiments, each pressure chamber 21 is equipped with an independent gas source interface and a gas pipeline. The gas pipeline includes a first gas pipe 211 and a second gas pipe (not shown in the figure). The first gas pipe 211 and the second gas pipe are connected. The first gas pipe 211 passes through the side wall of the metal mandrel 10 and is connected to the gas source interface. The second gas pipe is located inside the accompanying heat exchange channel and is arranged along the extension direction of the accompanying heat exchange channel. The second gas pipe is connected to an external gas source.

[0049] Specifically, a wiring groove is provided on the inner wall of the accompanying heat exchange channel, which extends along the direction of the accompanying heat exchange channel, and the second air pipe is installed in the wiring groove.

[0050] The soft mold layer 30 is applied to the outer forming surface of the flexible pressure cavity 20. The soft mold layer 30 is in direct contact with the prepreg.

[0051] Specifically, the thickness of the flexible mold layer 30 is 0.08mm-0.12mm. The material of the flexible mold layer 30 is selected to have a temperature greater than 200℃. More specifically, the flexible mold layer 30 is selected to be high-temperature silicone rubber with a Shore A hardness of 40-70. For example, high-temperature silicone rubber can be selected from methyl vinyl silicone rubber (VMQ) or fluorovinyl methyl silicone rubber (FVMQ).

[0052] Specifically, the soft mold layer 30 and the flexible pressure cavity 20 are integrally vulcanized. Of course, the soft mold layer 30 can also be assembled separately from the flexible pressure cavity 20. This application does not impose specific restrictions on the fixing method of the soft mold layer 30 and the flexible pressure cavity 20, as long as it can ensure that the soft mold layer 30 can expand uniformly and conform to the prepreg surface when pressure is applied by the flexible pressure cavity 20.

[0053] The pressure control assembly includes a controller 41, multiple pressure regulating valves 42 and multiple pressure sensors 43, each pressure regulating valve 42 and each pressure sensor 43 being electrically connected to the controller 41.

[0054] Each pressure chamber 21 is equipped with at least one pressure sensor 43 and a pressure regulating valve 42. The controller 41 receives the measurement signals of the pressure sensors corresponding to each pressure chamber 21 in real time and calculates the average pressure value. The average pressure value is compared with the corresponding target pressure value, thereby controlling the corresponding pressure regulating valve in real time to adjust the pressure inside the corresponding pressure chamber.

[0055] In some embodiments, a plurality of pressure sensors 43 are configured in the same pressure chamber 21. The plurality of pressure sensors 43 are located inside the pressure chamber 21 or between the pressure chamber 21 and the soft mold layer 30, and the plurality of pressure sensors are respectively arranged in the central region and the edge region of the pressure chamber 21.

[0056] Preferably, each pressure chamber 21 is equipped with two pressure sensors 43. One pressure sensor 43 is arranged in the central region of the pressure chamber, and the other pressure sensor 43 is arranged in the edge region of the pressure chamber.

[0057] Specifically, the pressure sensor 43 is a thin-film piezoresistive pressure sensor or a fiber Bragg grating pressure sensor. The pressure sensor 43 has a range of 0 MPa to 1.5 MPa and an accuracy class of not less than ±1%FS.

[0058] Specifically, the signal line of the pressure sensor 43 is led out through the pre-embedded channel inside the metal spindle 10 and connected to the controller 41.

[0059] Figure 2 This is a control logic diagram of a partitioned independent pressure regulating mandrel device for composite material parts according to an embodiment of this application.

[0060] See Figure 2 The pressure sensor 43 measures the pressure inside the pressure chamber 21 in real time and sends the measured pressure signal to the controller 41. The controller 41 processes the received pressure signal to obtain an average pressure value inside the pressure chamber 21 and compares this average pressure value with the target pressure of the pressure chamber. If the absolute value of the difference between the average pressure value and the target pressure is greater than a set threshold, an adjustment control signal is sent to the corresponding pressure regulating valve 42. The pressure regulating valve 42 adjusts its opening after receiving the control signal. If the absolute value of the difference between the average pressure value and the target pressure is less than the set threshold, no adjustment is required. Specifically, the set threshold is 0.05 MPa.

[0061] Specifically, when the absolute value of the difference between the average pressure and the target pressure is greater than a set threshold, if the difference between the average pressure and the target pressure is positive, an adjustment control signal is sent to the corresponding pressure regulating valve 42. After receiving the control signal, the pressure regulating valve 42 reduces the valve opening, thereby reducing the gas supply pressure entering the pressure chamber. If the difference between the average pressure and the target pressure is negative, an adjustment control signal is sent to the corresponding pressure regulating valve 42. After receiving the control signal, the pressure regulating valve 42 increases the valve opening, thereby increasing the gas supply pressure entering the pressure chamber.

[0062] In some embodiments, the pressure regulating valve 42 is an electromagnetic proportional regulating valve. The controller uses a PID algorithm. When the absolute value of the difference between the average pressure and the target pressure exceeds a set threshold, the controller calculates the adjustment amount based on the difference between the average pressure and the target pressure and sends an adjustment control signal to the corresponding pressure regulating valve 42. After receiving the control signal, the pressure regulating valve 42 adjusts the valve opening so that the pressure in the pressure chamber returns to the target pressure.

[0063] Specifically, the controller 41 reads data from each pressure sensor at a sampling frequency of not less than 10Hz.

[0064] Specifically, controller 41 is a PLC controller or an industrial control computer.

[0065] In some embodiments, the partitioned independent pressure regulating mandrel device 100 for composite material parts further includes a support layer (not shown). The support layer is sandwiched between the flexible pressure chamber 20 and the metal mandrel 10 to buffer the thermal expansion difference between the metal mandrel and the flexible pressure chamber and to provide uniform support for the flexible pressure chamber.

[0066] Figure 3This is a schematic diagram of a molding method for a composite material part according to another embodiment of this application.

[0067] See Figure 3 The molding method for composite material parts includes the following steps: Step S1: Obtain the target pressure of each pressure chamber during molding by testing the workpiece. The aforementioned partitioned independent pressure regulating mandrel device for composite material parts is used to form composite material test workpieces. All pressure chambers are set with a uniform initial pressure, and the formed composite material test workpieces are subjected to defect detection, and the defect location and type are recorded.

[0068] Adjust the target pressure setting value of the pressure chamber corresponding to the defect location according to the defect type, re-form the composite material test workpiece, record the pressure, defect location and type of each pressure chamber after adjustment, analyze the defect improvement effect, and repeatedly execute the parameter adjustment, component forming, data recording and effect analysis process until the quality of the formed composite material test workpiece meets the standard. Then, store the pressure value corresponding to each pressure chamber and use it as the target pressure of each pressure chamber when forming the formal composite material component.

[0069] Step S2: Using a partitioned independent pressure regulating mandrel device for composite material parts, the final composite material component is formed according to the target pressure of each pressure chamber obtained in step S1.

[0070] In some embodiments, in step S1, the method for adjusting the target pressure setting value of the pressure chamber corresponding to the defect location according to the defect type is as follows: if the defect type is a pore or bridging, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by stepwise increment; if the defect type is fiber buckling or resin loss, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by stepwise decrement.

[0071] Specifically, defect detection is non-destructive testing, such as using ultrasonic C-scanning or X-ray inspection.

[0072] Specifically, when adjusting the target pressure setting value of the pressure chamber corresponding to the defect location, the pressure value of the corresponding pressure chamber is gradually increased or decreased. For example, the pressure is increased or decreased by 0.1 MPa each time.

[0073] Figure 4 This is a schematic diagram of the molding process according to another embodiment of this application.

[0074] In some embodiments, such as Figure 4 As shown, the molding steps include: Step S2-1: Pre-inspection of the partitioned independent pressure regulating mandrel device used for composite material parts.

[0075] Step S2-2: Prepreg laying.

[0076] Step S2-3: perform vacuum bag packaging and vacuum leak detection.

[0077] Step S2-4: control the autoclave to heat up to a first temperature, and control each pressure regulating valve to increase the pressure of each pressure chamber to 40%-60% of the corresponding target pressure. This step can pre-expand the soft mold layer and remove volatile components from the prepreg.

[0078] Step S2-5: control the autoclave to continue heating up to a second temperature and pressurizing to a first pressure, meanwhile control each pressure regulating valve to pressurize each pressure chamber to the corresponding target pressure, and perform closed-loop control. The controller receives the collection signals from pressure transmitters corresponding to each of said pressure chambers, calculates an average pressure value, and compares the average pressure value with the corresponding target pressure value. If the absolute value of the difference between the average pressure value and the corresponding target pressure value does not exceed a set threshold, the pressure of the pressure chamber is kept unchanged; if the absolute value of the difference between the average pressure value and the corresponding target pressure value exceeds the set threshold, the controller controls the pressure regulating valve to adjust the internal pressure of the corresponding pressure chamber.

[0079] Step S2-6: control the autoclave to continue heating up to a third temperature and pressurizing to a second pressure, then perform heat and pressure preservation; meanwhile control the pressure chamber corresponding to the pulse pressurization partition to apply a pressure pulse-increasing molding pressure to the closed angle region of the composite part, wherein the initial value of pressure loading is the target pressure corresponding to the pressure chamber, and all other pressure chambers maintain pressure and perform closed-loop control.

[0080] Step S2-7: when the dielectric sensor monitors that the resin curing degree is ≥90%, perform cooling and demolding.

[0081] Specifically, in step S2-1, the pre-inspection includes: checking the air tightness and integrity of the partitioned independent pressure regulating mandrel device for composite parts, performing sensor zero calibration and loading initial process parameters, wherein the initial process parameters are the target pressures of the pressure chambers measured in step S1. The air tightness detection is implemented by pressurizing each pressure chamber and keeping the pressure for 10 min. If the pressure drop is ≤0.01 MPa, the air tightness is qualified.

[0082] Specifically, in step S2-2, prepreg layup comprises the following steps: first coating a release agent on the surface of the soft mold layer of the partitioned independent pressure regulating mandrel device for composite parts. Then lay prepregs according to the designed layup angle, perform vacuum pre-compaction once every 2-4 layups. During vacuum pre-compaction, the vacuum degree is ≥0.090 MPa, and the duration is ≥20 min.

[0083] Specifically, in step S2-3, auxiliary materials such as vacuum bag, breather felt and release film are used for packaging, then vacuumize to ≤-0.095 MPa and keep the pressure for 5 min. If the leakage rate is ≤3"Hg / 5min, the leak detection is qualified.

[0084] Specifically, the first temperature in step S2-4 is 80℃.

[0085] Specifically, steps S2-5 are the resin flow stage, the second temperature is 120℃, and the first pressure is 0.3MPa.

[0086] Specifically, in step S2-5, the threshold is set to ±0.05MPa.

[0087] Specifically, steps S2-6 are the curing stage, the third temperature is 180℃, and the second pressure is 0.6MPa.

[0088] Specifically, in steps S2-6, the pressure chamber applies pulsed incremental pressure to the closed-angle region of the component, using an intermittent pressure increase method: the pressure is increased once every 3 to 5 minutes, with a single pressure increase of 0.15 MPa; after each pressure increase, the current pressure is maintained until the next pressure increase node.

[0089] Specifically, in steps S2-6, heating oil is introduced into the conformal heat exchange channel 11 of the partitioned independent pressure regulating mandrel device for composite material parts to control the interface temperature difference between the partitioned independent pressure regulating mandrel device for composite material parts and the composite material parts.

[0090] Specifically, in steps S2-7, during the cooling and demolding process, the autoclave is gradually depressurized while all pressure chambers are simultaneously depressurized. When the autoclave temperature drops below 60°C, all pressure chambers are completely depressurized to atmospheric pressure. Then, the vacuum bag and auxiliary materials are removed, the soft mold layer elastically retracts, and the composite material part separates from the core film, completing the demolding process.

[0091] It should be noted that both the composite material test workpiece and the composite material final component are completed using the above-mentioned composite material part molding steps.

[0092] Specifically, during the molding process of composite parts, it is also necessary to save the pressure data collected in real time by each pressure sensor and finally form a complete pressure-time curve. Based on the pressure-time curve, it is determined whether the pressure during the molding process meets the process requirements, and the pressure state when defects occur is analyzed based on the pressure-time curve, providing a measured basis for process optimization.

[0093] Specifically, during the molding process of composite material components, while the autoclave is heated, a heating medium is simultaneously introduced into the conformal heat exchange channel 11 to make the heating rate and heat preservation temperature of the prepreg uniform. After curing, a cooling medium is introduced into the conformal heat exchange channel 11 to achieve controllable and uniform cooling, thus avoiding residual stress, deformation and warping of the component due to excessive internal and external temperature differences.

[0094] Specifically, a heating or cooling medium is introduced into the conformal heat exchange channel 11 to couple with the pressure of each pressure chamber. For example, the pressure of the pressure chamber is increased synchronously in the temperature range where the resin viscosity decreases, and the pressure of the pressure chamber is reduced after the resin gels, so as to match the rheological properties of the resin.

[0095] In some embodiments, the controller 41 includes a storage module. The storage module establishes a composite material part process database based on the stored types of composite material parts to be molded and the target pressures of each pressure chamber. When molding the composite material part, the target pressures corresponding to each pressure chamber are obtained from the composite material part process database according to the type of composite material part to be molded and the material. For the same composite material part, the saved process parameter data can be directly used for molding, without the need to obtain the target pressures of each pressure chamber through composite material test workpieces, thus shortening the process preparation cycle.

[0096] In some embodiments, the controller incorporates a machine learning model that predicts the pressure values ​​of each pressure chamber of the composite material part to be molded based on a composite material part process database and the geometric features and material of the composite material part to be molded. These predictions are then used as the initial pressure values ​​for each pressure chamber of the composite material test workpiece. This reduces the number of trial production iterations for the composite material test workpiece.

[0097] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the appended claims.

Claims

1. A partitioned independent pressure regulating mandrel device for composite material parts, characterized in that, include: A metal mandrel, wherein the outer forming surface of the metal mandrel is conformally matched to the cavity contour of the composite material part; A flexible pressurizing cavity is provided, which covers the outer forming surface of the metal mandrel. Multiple mutually isolated pressure chambers are formed inside the flexible pressurizing cavity. The pressure of each pressure chamber can be adjusted independently. Each pressure chamber is arranged in corresponding zones according to the geometric characteristics of the composite material part to be formed. A soft mold layer, which covers and is disposed on the outer forming surface of the flexible pressurization cavity; as well as A pressure control assembly includes: a controller, multiple pressure regulating valves, and multiple pressure sensors, each of the pressure regulating valves and each of the pressure sensors being electrically connected to the controller. Each pressure chamber is equipped with at least one pressure sensor and a pressure regulating valve. The controller receives the measurement signals from the pressure sensors corresponding to each pressure chamber in real time and calculates the average pressure value. The average pressure value is compared with the corresponding target pressure value, thereby controlling the corresponding pressure regulating valve to adjust the internal pressure of the corresponding pressure chamber in real time.

2. The partitioned independent pressure regulating mandrel device for composite material parts according to claim 1, characterized in that, It also includes a support layer sandwiched between the flexible pressurizing cavity and the metal mandrel, which buffers the thermal expansion difference between the metal mandrel and the flexible pressurizing cavity and provides uniform support for the flexible pressurizing cavity.

3. The partitioned independent pressure regulating mandrel device for composite material parts according to claim 1, characterized in that, The composite material part includes at least one of high-pressure zone, equal-pressure zone, pulsed pressure boosting zone, and gradient pressure zone, and the same composite material part to be molded may contain multiple zones of the same type. The high-pressure zone is the area corresponding to the open angle region of the composite material part or the root position of the rib. The pressure chamber corresponding to the high-pressure zone applies a molding pressure to the high-pressure zone that is greater than that of the autoclave. The pressure equalization zone is the region corresponding to the position of the straight segment or web area of ​​the composite material part. The pressure chamber corresponding to the pressure equalization zone applies a molding pressure equal to that of the autoclave to the pressure equalization zone. The pulsed pressure boosting zone corresponds to the closed-angle region of the composite material part. The pressure chamber corresponding to the pulsed pressure boosting zone applies a pulsed increasing molding pressure to the pulsed pressure boosting zone. The gradient pressure zone is the region corresponding to the thickness gradient transition area of ​​the composite material part. Corresponding to the gradient pressure zone are multiple pressure chambers, which apply gradient pressure to the gradient pressure zone.

4. The partitioned independent pressure regulating mandrel device for composite material parts according to claim 1, characterized in that, The metal mandrel is internally provided with conformal heat exchange channels. The wall thickness of the metal mandrel is not less than 10 mm. Each pressure chamber is equipped with an independent gas source interface and a gas pipeline. The gas pipeline includes a first gas pipe and a second gas pipe. The first gas pipe and the second gas pipe are connected. The first gas pipe passes through the side wall of the metal mandrel and is connected to the gas source interface. The second gas pipe is located inside the conformal heat exchange channel and is arranged along the extension direction of the conformal heat exchange channel. The second gas pipe is connected to an external gas source.

5. The partitioned independent pressure regulating mandrel device for composite material parts according to claim 1, characterized in that, The flexible pressurized cavity is either an airbag-type pressure cavity or a hydraulic cavity.

6. The partitioned independent pressure regulating mandrel device for composite material parts according to claim 1, characterized in that, Multiple pressure sensors are configured in the same pressure chamber. The multiple pressure sensors are located inside the pressure chamber or between the pressure chamber and the soft mold layer. The multiple pressure sensors are respectively arranged in the central region and the edge region of the pressure chamber.

7. A molding method for a composite material part, characterized in that, Includes the following steps: Step S1: Obtain the target pressure of each pressure chamber during molding through experimental testing. The composite material test workpiece is formed using the partitioned independent pressure regulating mandrel device for composite material parts as described in any one of claims 1-6, all pressure chambers are set with a uniform initial pressure, and the formed composite material test workpiece is subjected to defect detection, and the defect location and type are recorded. Adjust the target pressure setting value of the pressure chamber corresponding to the defect location according to the defect type, re-form the composite material test workpiece, record the pressure, defect location and type of each pressure chamber after adjustment, analyze the defect improvement effect, and repeatedly execute the parameter adjustment, component forming, data recording and effect analysis process until the quality of the formed composite material test workpiece meets the standard. Then, store the pressure value corresponding to each pressure chamber and use it as the target pressure of each pressure chamber when forming the formal composite material component. In step S2, the partitioned independent pressure regulating mandrel device for composite material parts is used to form the formal composite material component according to the target pressure of each pressure chamber obtained in step S1 and the same forming steps as the composite material test workpiece in step S1.

8. The molding method according to claim 7, characterized in that, In step S1, the method for adjusting the target pressure setting value of the pressure chamber corresponding to the defect location according to the defect type is as follows: if the defect type is a pore or bridging, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by step increasing; if the defect type is fiber buckling or resin loss, the target pressure setting value of the pressure chamber corresponding to the defect location is adjusted by step decreasing.

9. The molding method according to claim 7, characterized in that, The molding step includes: Pre-inspection of the partitioned independent pressure regulating mandrel device for composite parts; Prepreg laying; Perform vacuum bag sealing and vacuum leak detection; Control the autoclave to heat up to the first temperature, and simultaneously control each pressure regulating valve to increase the pressure in each pressure chamber to 40%-60% of the corresponding target pressure; The autoclave is controlled to continue heating to a second temperature and pressurizing to a first pressure. At the same time, each pressure regulating valve is controlled to pressurize each pressure chamber to the corresponding target pressure, and closed-loop control is performed. The controller receives the signals collected by the pressure transmitters corresponding to each pressure chamber and calculates the average pressure value. The average pressure value is compared with the corresponding target pressure value. If the absolute value of the difference between the average pressure value and the corresponding target pressure value does not exceed a set threshold, the pressure of the pressure chamber is kept unchanged. If the absolute value of the difference between the average pressure value and the corresponding target pressure value is greater than the set threshold, the controller controls the pressure regulating valve to adjust the internal pressure of the corresponding pressure chamber. The autoclave is controlled to continue heating to the third temperature and pressurizing to the second pressure, and then heat and pressure are maintained. At the same time, the pressure chamber corresponding to the pulse pressurization zone is controlled to apply a pulse-increasing molding pressure to the closed-angle region of the composite material part. The initial pressure loading value is the target pressure corresponding to the pressure chamber. All other pressure chambers are pressurized and closed-loop controlled. When the dielectric sensor detects that the resin curing degree is ≥90%, cooling and demolding are performed.

10. The molding method according to claim 7, characterized in that, The controller includes a storage module, which establishes a composite material part process database based on the stored types of composite material parts to be molded and the target pressures of each pressure chamber. When molding composite material parts, the target pressures corresponding to each pressure chamber are obtained from the composite material part process database according to the type of composite material part to be molded and the material.

11. The molding method according to claim 10, characterized in that, The controller has a built-in machine learning model. The machine learning model predicts the pressure value of each pressure chamber of the composite material part to be formed based on the composite material part process database and the geometric features and material of the composite material part to be formed, and uses it as the initial pressure value of each pressure chamber of the composite material test workpiece.

Images