Composite material concave surface type rotary body mold and structural part forming method

Abstract

The invention discloses a composite material concave surface type revolving body mold and a structural part forming method in the technical field of composite material structural part forming. The composite material concave surface type revolving body mold and the structural part forming method comprise the steps of material preparation and mold treatment, paving and reinforcing, vacuum bag packaging and leak detection, autoclave curing and detection, nondestructive demolding and precise cutting. The forming mold is arranged to be of an up-down structure and is composed of the insert and the lower portion integrally, the mold joint is arranged on the cylindrical face above the area with the maximum curvature change of the product, the integrity of the mold is guaranteed to the maximum degree, the product can be smoothly separated from the integrated lower mold through clamping of the demolding tool and the jackscrew effect, and the forming efficiency is improved. And uniform heat conduction in the workpiece forming process is guaranteed, the problem that the profile tolerance of a product is out of tolerance due to expansion deformation of the mold is effectively solved, the molded surface precision of the product is guaranteed, a rotary body structure has high bearing capacity, deformation and warping are not prone to being generated in the forming process, damage is not prone to being generated in the demolding process, and the later use quality is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of composite material structural component molding technology, and in particular to a composite material concave rotating mold and a method for molding structural components. Background Technology

[0002] The aerospace industry has absolute requirements for lightweighting. Thin-walled, concave-shaped composite material components for rotating bodies are frequently used in aerospace applications. Composite materials, due to their high specific strength and high specific modulus, are widely used in the aerospace field. Streamlined design concepts are widely used in aircraft, submarines, automobiles, and ships. The streamlined shape of a product places stringent requirements on the surface profile, as well as the appearance, internal quality, and mechanical properties of the material itself, which greatly restricts the application of composite materials.

[0003] Aerospace products require high-precision contours. During the curing process of composite materials, the coefficient of thermal expansion between the mold material and the composite material, as well as the thermal expansion of the material itself, all affect the surface accuracy of the product. To prevent deformation of high-temperature composite materials under high temperature and pressure during molding, circumferential variable-thickness reinforcement is required in areas of maximum curvature change and stress concentration in the structural components. However, the molding process for concave rotating bodies is relatively complicated and difficult due to the limitations of composite material lamination characteristics, requiring high operator skills and resulting in a low product qualification rate. The thickness of the thickened area after lamination is unstable, and the surface has wrinkles and other problems. Therefore, ensuring the flatness of the inner and outer surfaces, the delamination method in the variable-thickness area, and accurate positioning are particularly important for rotating body parts. This application provides a composite material concave rotating body mold and structural component molding method. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a composite material concave rotating mold and a method for forming structural components.

[0005] The objective of this invention is achieved as follows: a composite material concave rotary mold, comprising inserts and a lower mold, wherein there are two inserts, which are arranged correspondingly and interlock to form a ring structure, the inserts are arranged correspondingly to the lower mold, and a positioning pin is provided between the inserts and the lower mold to assist the inserts in cooperating with the lower mold.

[0006] Optionally, the insert has a clearance groove, and the lower mold has a positioning ring. The clearance groove and the positioning ring are correspondingly arranged, and the positioning ring is inserted into the clearance groove.

[0007] Optionally, the insert has a first connecting hole, and a lifting ring is threaded into the first connecting hole. The lower mold has a second connecting hole on its outer side, and a lifting lug is threaded into the second connecting hole.

[0008] A method for molding a concave rotating composite material structure includes the following steps: S1, Material preparation and mold treatment: retrieve the electronic blanking diagram, check the integrity of the material, arrange the sheet according to the layup sequence, inspect the mold surface and scribing lines, and apply release agent; S2, Laying: Set the layup according to the laying enhancement strategy, set the reinforcement layer based on the area of ​​product thickness variation, and perform vacuuming; S3, Vacuum Packaging Bag: Set up high-temperature curing auxiliary materials and vacuum nozzle, perform vacuuming and detect and record the vacuum degree of the vacuum bag; S4, Curing: The semi-finished parts are placed in an autoclave for cold pressing test to check the qualification of the semi-finished parts. S5, Demolding: Parts are demolded using a demolding device; S6, Cutting: Mark the semi-finished parts and finish them to the specified dimensions.

[0009] Optionally, the tiling enhancement strategy in step S2 includes layup design and tiling process; The specific ply design is as follows: Thickness reinforcement is used in areas of maximum curvature change and stress concentration in structural components. Among them, the interlayer angle in the middle part of the ply is selected as 90°, and 45° prepreg is used for laying; The inner and outer surfaces of the skin are laid with ±45° prepreg; The thickness reinforcement treatment specifically involves: setting strip-shaped composite material in the reinforcement area, with a gradually changing layup width, and laying and filling it along the circumferential direction.

[0010] Optionally, the paving process specifically includes: The number of layers is 15, including 12 whole layers and 3 local reinforcement layers; Define the reinforcement layer installation, divide the areas of thickness variation according to their width from smallest to largest, and name them 1#, 2# and 3#; Define the axial direction as 0°. Prepreg angles include 0°, 45°, -45°, and 90°; The layup direction of the 0° prepreg is consistent with the circumferential force direction of the rotating body structure; During installation, measure downwards from the top edge of the mold to determine the location of the reinforcing layer; In particular, for locations where the thickness of the reinforcing layer varies, strip-shaped composite material layup is used, with the layup width gradually changing along the circumferential direction; Optionally, during installation, the prepreg is laid with the top and bottom margins evenly spaced around the perimeter. Pre-vacuuming is performed after every 4 layers of prepreg, and the pre-vacuuming time is 15 minutes. The pre-vacuuming time is 4 hours after the last layer of prepreg is laid; Record the start and end times when the vacuum level inside the vacuum bag is ≤-0.085MPa. When laying the tiles at the edges, a butt joint strategy is used, and the upper and lower layers are laid with staggered overlaps.

[0011] Optionally, the docking strategy is specifically as follows: During installation, the edges of adjacent prepregs should be in direct contact. If adjacent prepregs cannot be in direct contact, a splice seam should be set in the fiber direction of the prepregs. The maximum width of the splice seam should be less than 2 mm. The joints are treated with auxiliary fixing measures, specifically by using high-temperature resistant positioning strips to be symmetrically pasted along both sides of the joints to ensure the stability of the installation.

[0012] Optionally, the process of step S3 is as follows: S31, peeling cloth, non-porous isolation film, high-temperature breathable felt and high-temperature vacuum bag film are placed sequentially on the upper surface of the layer. S32, place the vacuum nozzle to draw a vacuum. When the vacuum level inside the vacuum bag reaches -0.085MPa, stop drawing a vacuum and check whether there is bridging between the vacuum bag and the mold. If there is, take measures to level it. S33, detect and record the vacuum level of the vacuum bag, continue to evacuate, stop evacuating when the vacuum level inside the vacuum bag reaches -0.092MPa, and perform vacuum leak testing; If the vacuum level drops by no more than 0.02 MPa within 10 minutes, the vacuum bag is considered properly sealed. If the vacuum level drops by more than 0.02 MPa, check for leaks in the vacuum bag until the vacuum level returns to normal.

[0013] Optionally, the process of demolding the parts using a demolding device is as follows: S51, remove the insert above the lower mold using auxiliary tools; S52, fasten the demolding device onto the semi-finished structural component; S53, the semi-finished structural component is fixed by positioning bolts and positioning nuts; S54, rotate the adjusting bolts on both sides to separate the semi-finished structural component from the lower mold and demold it through the set screw.

[0014] Compared with existing technologies, the advantages of this invention are as follows: Processing the composite material rotary structure using an autoclave is simple and efficient. During the composite material layup process, local circumferential reinforcement can eliminate thermal deformation and warping, reduce internal stress, thereby improving molding quality and effectively preventing demolding damage. The 0° direction of the composite material layer layup is consistent with the force direction of the rotary structure. When the rotary structure obtained using the above structure is under load, the force can be transmitted along the load-bearing direction, reducing the impact on the relatively weak interlayers of the composite material, thereby improving the load-bearing capacity of the rotary structure. Laying up the composite material according to the above layup scheme enables the obtained rotary structure to have strong load-bearing capacity, is less prone to deformation and warping during molding, and is less prone to damage during demolding, ensuring the quality of later use. The molding die consists of an upper insert and a lower part. The die joint is designed on the cylindrical surface above the area of ​​greatest curvature change in the product to ensure the integrity of the die. Through the clamping of the demolding fixture and the action of the ejector screw, the product can be smoothly demolded. The integrated lower die can reduce manufacturing costs, ensure uniform heat conduction during the molding process, effectively solve the problem of product contour deviation caused by die expansion and deformation, and ensure the accuracy of product surface. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the composite material rotating body structure provided by the present invention.

[0017] Figure 2 yes Figure 1 A cross-sectional diagram.

[0018] Figure 3 This is a schematic diagram of the mold assembly provided by the present invention.

[0019] Figure 4 This is an exploded view of the mold provided by the present invention.

[0020] Figure 5 This is a schematic diagram of the insert structure provided by the present invention.

[0021] Figure 6 This is a schematic diagram of the assembly of the mold and the rotating body provided by the present invention.

[0022] Figure 7 This is a schematic diagram of the demolding component structure provided by the present invention.

[0023] Figure 8 This is a flowchart of the molding method for a concave rotating composite material structure provided by the present invention.

[0024] In the diagram: 1. Insert; 11. Clearance groove; 12. First connecting hole; 13. Lifting ring; 2. Lower mold; 21. Positioning ring; 22. Second connecting hole; 23. Lifting lug; 3. Positioning pin; 4. Fastening bolt; 5. Demolding device; 51. Positioning bolt; 52. Positioning nut; 53. Adjusting bolt. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figures 1 to 8 The composite material concave rotary mold shown includes an insert and a lower mold. There are two inserts, which are arranged correspondingly and interlock to form a ring structure. The inserts are arranged correspondingly to the lower mold. A positioning pin is provided between the inserts and the lower mold to assist the inserts in cooperating with the lower mold.

[0027] Furthermore, the traditional left-right structure mold is changed to a top-bottom structure. Since the structural component is a rotating body and is subjected to circumferential force, the top-bottom structure mold provides the structural component with the whole mold as support in the circumferential direction, ensuring the performance of the material in the direction of force, and there are no mold seams in the appearance of the structural component. Furthermore, the mold consists of an upper insert and a lower mold. The joint between the mold insert and the lower mold is located on the cylindrical surface above the area of ​​the greatest curvature change in the structure. This facilitates demolding while maximizing the integrity of the mold. The integrated lower mold design effectively reduces manufacturing costs, ensures uniform heat conduction during the molding process, effectively solves the problem of product profile deviation caused by mold expansion and deformation, and improves the surface accuracy of the product.

[0028] Specifically, the insert has a clearance groove, the lower mold has a positioning ring, the clearance groove and the positioning ring are correspondingly arranged, and the positioning ring is inserted into the clearance groove.

[0029] Furthermore, during installation, the positioning ring on the lower mold is used to cooperate with the clearance groove on the insert to achieve quick positioning, ensuring that the insert and the lower mold are strictly aligned when the mold is closed, avoiding misalignment, and providing rigid constraints to prevent surface errors caused by mold closing deviations, thereby improving the product contour accuracy. The clearance groove allows the positioning ring to separate smoothly during mold opening, avoiding demolding difficulties caused by mechanical interference. At the same time, the joint is located on the cylindrical surface above the area of ​​greatest curvature change. Combined with the guiding effect of the positioning ring, this makes the demolding process smoother and reduces damage to the part.

[0030] Specifically, the insert has a first connecting hole, and a lifting ring is threaded into the first connecting hole. The lower mold has a second connecting hole on its outer side, and a lifting lug is threaded into the second connecting hole.

[0031] Furthermore, the lifting rings and lugs are connected to the inserts and lower molds via standardized threaded connections, making the lifting, handling, and positioning of heavy molds simple and efficient. Secondly, the lugs can improve operational safety, avoid work-related injuries that may be caused by manual handling of heavy molds, and ensure the stability of the mold during the lifting process. Finally, the conversion between processes such as autoclave molding, demolding, and maintenance of the mold is faster, shortening the production cycle.

[0032] A method for molding a concave rotating composite material structure includes the following steps: S1, Material preparation and mold processing: retrieve the electronic blanking diagram, check the integrity of the material, arrange the sheet according to the layup sequence, check the mold surface and scribing lines, and apply mold release agent to the punch; S2, Laying: Set the layup according to the laying enhancement strategy, set the reinforcement layer based on the area of ​​product thickness variation, and perform vacuuming; S3, Vacuum Packaging Bag: Set up high-temperature curing auxiliary materials and vacuum nozzle, perform vacuuming and detect and record the vacuum degree of the vacuum bag; S4, Curing: The semi-finished parts are placed in an autoclave for cold pressing test to check the qualification of the semi-finished parts. S5, Demolding: Parts are demolded using a demolding device; S6, Cutting: Mark the semi-finished parts and finish them to the specified dimensions.

[0033] Furthermore, the present invention aims to provide a molding die and molding method for a thin-walled concave rotary body of variable thickness composite material, in order to solve the quality problems of existing variable thickness rotary body structures, such as thermal deformation and warping in stress concentration areas, excessive load-bearing efficiency, easy demolding damage or difficulty in demolding, and product contour deviation caused by mold deformation, which lead to local strength reduction, appearance wrinkles, and excessive surface contour deviation of the product.

[0034] Furthermore, during the material preparation stage, the bag surface must be free of moisture before the sealed bag can be opened. Materials with moisture on the roll or inside the bag should be discarded. Then, when the opened material is moved outside the clean room, it must be packaged in a sealed moisture-proof bag. Next, the prepreg should be stored in a sealed moisture-proof box at -18℃ or below for 180 days. Under sealed conditions of 18℃-26℃, relative humidity not exceeding 65%, the storage period is a cumulative 30 days (720 hours). Prepreg that exceeds the storage period must be re-inspected for quality consistency before it can be used. Furthermore, before laying the prepreg, it is necessary to retrieve the electronic cutting diagram, cut the material using the cutting machine, and check whether the cut material sheets are complete and undamaged. Among them, when the prepreg is taken out of the cold storage, it should be sealed before the material reaches room temperature. The thawing time of the material should not be less than 6 hours, and the sealing film or blue film debris should be cleaned up in time. Secondly, arrange the sheet material in the order of layering, and compare the cut sheet material with the electronic cutting diagram to check for any missing sheet material or obvious cutting errors.

[0035] Specifically, the tiling enhancement strategy in step S2 includes layup design and tiling process; The specific ply design is as follows: Thickness reinforcement is used in areas of maximum curvature change and stress concentration in structural components. Among them, the interlayer angle in the middle part of the ply is selected as 90°, and 45° prepreg is used for laying; The inner and outer surfaces of the skin are laid with ±45° prepreg; The thickness reinforcement treatment specifically involves: setting strip-shaped composite material in the reinforcement area, with a gradually changing layup width, and laying and filling it along the circumferential direction.

[0036] Furthermore, the design thickness of composite material parts should not exceed 2mm. Since laminate structures of this thickness are very sensitive to low-energy impact damage, they will place a great burden on operation and maintenance. Therefore, taking advantage of the design characteristics of composite material layup, under the condition that the structural mass does not increase significantly, circumferential variable thickness reinforcement measures should be carried out in the areas where the curvature of the structural parts changes the most and stress concentration is greatest to ensure that the product structure has sufficient strength. In specific ply design, the main focus is on ensuring that the structure can most effectively and directly transfer loads in a given direction, thereby improving load-bearing capacity, structural stability, and resistance to impact damage. Specifically: First, the rotating body structure is mainly based on low-energy impact. Based on the principle of effective force transmission, the interlayer angle of the middle part of the ply should be selected as 90° prepreg as much as possible, and 45° ply is preferred. ±45° ply is selected on the inner and outer surfaces of the skin.

[0037] Among them, the 90° prepreg is used to bear the axial load. When the rotating structure is subjected to low-energy impact, such as slight collision or pressure fluctuation, it mainly bears the axial tensile or compressive load. The fiber direction of the 90° prepreg layup is consistent with the axis of the rotating body, which can most effectively transfer and resist such loads, avoid structural instability or deformation. At the same time, in cylindrical or arc-shaped structures, the 90° prepreg layup can restrain radial expansion or contraction, similar to the effect of stirrups, to maintain the stability of the structural shape. The 45° prepreg layup is used to disperse shear stress. When a rotating body is impacted, the stress will be transmitted along the curved surface in the form of shear. The fiber direction of the ±45° layup forms a 45° angle with the direction of the principal stress, which can efficiently absorb shear force and avoid stress concentration that could lead to delamination or cracking. Unidirectional layups, such as full 0° or 90° prepreg layups, can lead to anisotropy in mechanical properties. ±45° layup combinations can balance the in-plane stiffness and strength of the structure and improve multi-directional load-bearing capacity. At the same time, rotating bodies are prone to torsion when rotating or subjected to lateral forces. ±45° layups can resist torsional loads through fiber cross-linking. Furthermore, the inner and outer surfaces of the skin are plyed at ±45° to resist bending and impact. As the outermost layer of the structure, the skin directly bears the impact, while the ±45° ply can disperse the impact energy to a larger area through the fiber cross network, reducing local damage such as dents or cracks. Using ±45° layup at the same angle on the inner and outer surfaces of the skin can form a symmetrical structure, avoiding the bending-stretch coupling effect caused by asymmetrical layup and reducing the risk of delamination. Finally, ±45° layup makes it easier to fit complex surfaces when laying on curved surfaces, reducing defects such as wrinkles or fiber buckling.

[0038] Furthermore, for the parts where the thickness of the local reinforcement area varies, strip-shaped composite materials are used, with the width of the layup gradually changing, resulting in a gradual change in thickness. These are laid circumferentially within the local reinforcement area to fill the local filling area to the required shape. By employing a gradually wide strip layup, the thickness transitions smoothly, effectively dispersing stress, avoiding localized high-stress areas, and improving the fatigue life of the structure. Furthermore, the strip layup in the reinforcing zone is laid circumferentially, ensuring that the fiber direction aligns with the principal stress direction, maximizing the axial load-bearing capacity of the fibers, significantly improving local stiffness and strength, and giving the resulting rotating structure a strong load-bearing capacity. It is also less prone to deformation and warping during molding, ensuring the quality of later use.

[0039] Specifically, the paving process is as follows: The number of layers is 15, including 12 whole layers and 3 local reinforcement layers; Define the reinforcement layer installation, divide the areas of thickness variation according to their width from smallest to largest, and name them 1#, 2# and 3#; Define the axial direction as 0°. Prepreg angles include 0°, 45°, -45°, and 90°; The layup direction of the 0° prepreg is consistent with the circumferential force direction of the rotating body structure; During installation, lay the tiles in the center from widest to narrowest width, and measure downwards from the top edge of the mold to determine the location of the reinforcing layer. In particular, for locations where the thickness of the reinforcing layer varies, strip-shaped composite material lay-up is used, with the lay-up width gradually changing along the circumferential direction.

[0040] Furthermore, centered reinforcement, meaning the reinforcement layers are symmetrically distributed along the centerline of the structure, ensures that the load is transmitted along the neutral axis and prevents bending coupling effects caused by asymmetrical reinforcement. Secondly, symmetrical layup can balance circumferential stress, avoid local high-stress areas, and improve the fatigue life of the structure.

[0041] Furthermore, when the thickness of the reinforcing zone changes, if the layup width changes suddenly, it will lead to stress concentration, such as a sharp increase in interlaminar shear stress. Using strip layup with gradually varying width can make the stress transition smoothly, reduce the risk of delamination, and make the fiber direction consistent with the principal stress direction, thereby maximizing the fiber load-bearing efficiency.

[0042] Specifically, during installation, the prepreg is laid with equal spacing at the top and bottom edges and around the perimeter. Pre-vacuuming is performed after every 4 layers of prepreg, and the pre-vacuuming time is 15 minutes. The pre-vacuuming time is 4 hours after the last layer of prepreg is laid; Record the start and end times when the vacuum level inside the vacuum bag is ≤-0.085MPa. When laying the tiles at the edges, a butt joint strategy is used, and the upper and lower layers are laid with staggered overlaps.

[0043] Furthermore, in the composite material layup process, the use of prepreg with equidistant top and bottom margins around the perimeter can ensure neat layup edges, facilitate vacuum bag sealing, optimize resin flow, and avoid local accumulation or resin deficiency. In particular, a 15-minute pre-vacuuming process is performed every 4 layers to periodically remove air bubbles between layers, compact the layers, reduce porosity, detect laying defects in advance, and avoid excessive resin loss. Furthermore, after the final layer is laid, a 4-hour pre-vacuum is performed to ensure that residual gas is fully removed before curing, so that the layer structure is stable and the resin is evenly distributed. The vacuum degree setting of ≤-0.085MPa can ensure sufficient compaction effect.

[0044] The edge tiling adopts a butt joint strategy to avoid stress concentration caused by sudden changes in local thickness. The upper and lower layers are laid with staggered overlaps, which can disperse the stress at the joint, optimize the load transfer path, and improve the interlayer bonding strength and anti-delamination ability.

[0045] Specifically, the docking strategy is as follows: During installation, the edges of adjacent prepregs should be in direct contact. If adjacent prepregs cannot be in direct contact, a splice seam should be set in the fiber direction of the prepregs. The maximum width of the splice seam should be less than 2 mm. The joints are treated with auxiliary fixing measures, specifically by using high-temperature resistant positioning strips to be symmetrically pasted along both sides of the joints to ensure the stability of the installation.

[0046] Furthermore, the docking strategy, by controlling the width of the splice seam and using high-temperature resistant positioning strips for symmetrical fixation, can ensure the structural integrity and process reliability of the composite material layup. Specifically, direct contact between the edges of adjacent prepregs can minimize the resin enrichment area and avoid stress concentration caused by local thickening. When seams must be installed, limiting the seam width to within 2mm can prevent strength loss caused by fiber discontinuity, while ensuring that the resin can fully impregnate the seam area. Symmetrical application of high-temperature resistant positioning strips has multiple advantages: First, the adhesive strip can firmly fix the joint position during the laying and pre-compacting stages, preventing the prepreg from shifting or warping. Second, its high-temperature resistance ensures that it will not soften or fail during the subsequent curing process, maintaining the stability of the joint. Third, the symmetrical bonding method can balance the constraint forces on both sides of the joint, avoiding twisting deformation caused by fixing on one side. Therefore, the method provided in this application not only ensures the continuity of the fibers but also controls the resin flow path, so that the joint area can effectively transfer the load without becoming a weak point.

[0047] Compared to traditional overlapping methods, the butt joint strategy significantly reduces the risk of thickness abrupt changes, improves the accuracy of layup dimensions, and enhances the mechanical properties of the product by optimizing fiber arrangement.

[0048] Specifically, the process of step S3 is as follows: S31, peeling cloth, non-porous isolation film, high-temperature breathable felt and high-temperature vacuum bag film are placed sequentially on the upper surface of the layer. S32, place the vacuum nozzle to draw a vacuum. When the vacuum level inside the vacuum bag reaches -0.085MPa, stop drawing a vacuum and check whether there is bridging between the vacuum bag and the mold. If there is, take measures to level it. S33, detect and record the vacuum level of the vacuum bag, continue to evacuate, stop evacuating when the vacuum level inside the vacuum bag reaches -0.092MPa, and perform vacuum leak testing; If the vacuum level drops by no more than 0.02 MPa within 10 minutes, the vacuum bag is considered properly sealed. If the vacuum level drops by more than 0.02 MPa, check for leaks in the vacuum bag until the vacuum level returns to normal.

[0049] Furthermore, firstly, a combination of multi-layer functional materials (peeling cloth, non-porous isolation membrane, high-temperature breathable felt, etc.) is used for laying, which can effectively guide the resin and prevent adhesion, and can also evenly distribute the vacuum pressure to avoid uneven compaction caused by local bridging. Secondly, phased vacuuming combined with bridging inspection ensures that the vacuum bag and mold are completely fitted, eliminating pores or delamination defects caused by gas retention. By monitoring pressure changes in real time, leaks can be quickly located and repaired, ensuring the stability of the vacuum environment during the curing process and thus avoiding uneven resin distribution or fiber displacement caused by pressure fluctuations.

[0050] Specifically, the process of demolding the parts using a demolding device is as follows: S51, remove the insert above the lower mold using auxiliary tools; S52, fasten the demolding device onto the semi-finished structural component; S53, the semi-finished structural component is fixed by positioning bolts and positioning nuts; S54, rotate the adjusting bolts on both sides to separate the semi-finished structural component from the lower mold and demold it through the set screw.

[0051] Furthermore, the combination of step-by-step removal of inserts and gradual lifting can evenly distribute demolding stress, avoiding structural deformation or surface damage caused by excessive local stress. The positioning bolts and nuts of the demolding device work together to ensure that the semi-finished product remains stably centered during demolding, preventing edge tearing caused by misalignment. Meanwhile, the adjusting bolts on both sides apply symmetrical force to make the structural components separate smoothly from the mold, effectively reducing the risk of interface peeling. Furthermore, a flexible buffer layer is added at the positioning bolt connection to absorb the impact energy during mechanical adjustment and avoid frictional damage caused by direct contact between metal parts and composite materials, thus protecting the surface quality of the product and improving the demolding success rate of large-sized or complex curved surface components.

[0052] In summary, this invention utilizes an autoclave to process composite material rotary structures, resulting in a simple and efficient process. During the composite material layup, local circumferential reinforcement eliminates thermal deformation and warping, reduces internal stress, and thus improves molding quality while effectively preventing demolding damage. The 0° direction of the composite material layer layup aligns with the stress direction of the rotary structure. When subjected to load, the rotary structure obtained using the above structure allows force to be transmitted along the load-bearing direction, reducing the impact on the relatively weak interlayer composite material layers and thereby improving the load-bearing capacity of the rotary structure. Laying up the composite material according to the above layup scheme results in a rotary structure with strong load-bearing capacity, less prone to deformation and warping during molding, and less susceptible to damage during demolding, ensuring quality for later use. The molding die consists of an upper insert and a lower integral part. The die joint is designed on the cylindrical surface above the area of ​​greatest curvature change of the product, which ensures the integrity of the die to the greatest extent. Through the clamping of the demolding tool and the action of the ejector screw, the product can be smoothly demolded. The integrated lower die can reduce the manufacturing cost, ensure uniform heat conduction during the molding process, effectively solve the problem of product contour deviation caused by die expansion and deformation, and ensure the product surface accuracy.

[0053] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A composite material concave rotary mold, comprising an insert and a lower mold, characterized in that: The number of inserts is two, the two inserts are set correspondingly, and the two inserts are fastened together to form a ring structure. The inserts are set correspondingly to the lower mold, and a positioning pin is provided between the inserts and the lower mold. The positioning pin is used to assist the inserts in cooperating with the lower mold.

2. The composite material concave rotary mold according to claim 1, characterized in that: The insert has a clearance groove, and the lower mold has a positioning ring. The clearance groove and the positioning ring are correspondingly arranged, and the positioning ring is inserted into the clearance groove.

3. The composite material concave rotary mold according to claim 1, characterized in that: The insert has a first connecting hole, and a lifting ring is threaded into the first connecting hole. The lower mold has a second connecting hole on its outer side, and a lifting lug is threaded into the second connecting hole.

4. A method for molding a concave rotating composite material structure, characterized in that, Includes the following steps: S1, Material preparation and mold treatment: retrieve the electronic blanking diagram, check the integrity of the material, arrange the sheet according to the layup sequence, inspect the mold surface and scribing lines, and apply release agent; S2, Laying: Set the layup according to the laying enhancement strategy, set the reinforcement layer based on the area of ​​product thickness variation, and perform vacuuming; S3, Vacuum Packaging Bag: Set up high-temperature curing auxiliary materials and vacuum nozzle, perform vacuuming and detect and record the vacuum degree of the vacuum bag; S4, Curing: The semi-finished parts are placed in an autoclave for cold pressing test to check the qualification of the semi-finished parts. S5, Demolding: Parts are demolded using a demolding device; S6, Cutting: Mark the semi-finished parts and finish them to the specified dimensions.

5. The method for forming a concave rotating composite material structure according to claim 4, characterized in that: The tiling enhancement strategy in step S2 includes layup design and tiling process; The specific installation process is as follows: The number of layers is 15, including 12 whole layers and 3 local reinforcement layers; Define the reinforcement layer installation, divide the areas of thickness variation according to their width from smallest to largest, and name them 1#, 2# and 3#; Define the axial direction as 0°. Prepreg angles include 0°, 45°, -45°, and 90°; The layup direction of the 0° prepreg is consistent with the circumferential force direction of the rotating body structure; During installation, measure downwards from the top edge of the mold to determine the location of the reinforcing layer; In particular, for locations where the thickness of the reinforcing layer varies, strip-shaped composite material lay-up is used, with the lay-up width gradually changing along the circumferential direction.

6. The method for forming a concave rotating composite material structure according to claim 5, characterized in that: The specific ply design is as follows: Thickness reinforcement is used in areas of maximum curvature change and stress concentration in structural components. Among them, the interlayer angle in the middle part of the ply is selected as 90°, and 45° prepreg is used for laying; The inner and outer surfaces of the skin are laid with ±45° prepreg; The thickness reinforcement treatment specifically involves: setting strip-shaped composite material in the reinforcement area, with a gradually changing layup width, and laying and filling it along the circumferential direction.

7. The method for forming a concave rotating composite material structure according to claim 6, characterized in that: During installation, the prepreg is laid with equal spacing at the top and bottom edges and around the perimeter. Pre-vacuuming is performed after every 4 layers of prepreg, and the pre-vacuuming time is 15 minutes. The pre-vacuuming time is 4 hours after the last layer of prepreg is laid; Record the start and end times when the vacuum level inside the vacuum bag is ≤-0.085MPa. When laying the tiles at the edges, a butt joint strategy is used, and the upper and lower layers are laid with staggered overlaps.

8. A method for forming a composite concave rotating body structure according to claim 7, characterized in that: The specific docking strategy is as follows: During installation, the edges of adjacent prepregs should be in direct contact. If adjacent prepregs cannot be in direct contact, a splice seam should be set in the fiber direction of the prepregs. The maximum width of the splice seam should be less than 2 mm. The joints are treated with auxiliary fixing measures, specifically by using high-temperature resistant positioning strips to be symmetrically pasted along both sides of the joints to ensure the stability of the installation.

9. A method for forming a composite concave rotating body structure according to claim 4, characterized in that: The specific process of step S3 is as follows: S31, peeling cloth, non-porous isolation film, high-temperature breathable felt and high-temperature vacuum bag film are placed sequentially on the upper surface of the layer. S32, place the vacuum nozzle to draw a vacuum. When the vacuum level inside the vacuum bag reaches -0.085MPa, stop drawing a vacuum and check whether there is bridging between the vacuum bag and the mold. If there is, take measures to level it. S33, detect and record the vacuum level of the vacuum bag, continue to evacuate, stop evacuating when the vacuum level inside the vacuum bag reaches -0.092MPa, and perform vacuum leak testing; If the vacuum level drops by no more than 0.02 MPa within 10 minutes, the vacuum bag is considered properly sealed. If the vacuum level drops by more than 0.02 MPa, check for leaks in the vacuum bag until the vacuum level returns to normal.

10. A method for forming a concave rotating composite material structure according to claim 4, characterized in that: The specific process of demolding parts using a demolding device is as follows: S51, remove the insert above the lower mold using auxiliary tools; S52, fasten the demolding device onto the semi-finished structural component; S53, the semi-finished structural component is fixed by positioning bolts and positioning nuts; S54, rotate the adjusting bolts on both sides to separate the semi-finished structural component from the lower mold and demold it through the set screw.

Images