Composite material arc rib forming tool and forming method for upper and lower flanging closed angle structure

Abstract

The application provides a kind of up and down flanging closed angle structure composite material arc rib forming tool and forming method, tool includes upper forming die, lower forming die, strip positioning block and combined positioning pin;The profile of upper forming die is adapted to the upper profile of arc rib part, and first combined positioning hole and first strip positioning groove are provided on the upper forming die;The profile of lower forming die is adapted to the lower profile of arc rib part, and lower forming die includes lower forming die main body and lower forming die sub-block detachably connected to lower forming die main body, and second combined positioning hole and second strip positioning groove corresponding to upper forming die are provided on lower forming die main body;The profile of strip positioning block matches with first strip positioning groove and second strip positioning groove;Combined positioning pin matches with first combined positioning hole and second combined positioning hole.The application solves the demoulding problem of closed angle structure through the separable lower die sub-block and the specific separation surface angle design.

Description

Technical Field

[0001] This invention relates to the field of composite material manufacturing technology, and more specifically, to a molding tool and method for forming arc-shaped ribs of composite materials with upper and lower flanged closed angle structures. Background Technology

[0002] Composite materials, due to their high specific strength, high specific stiffness, strong design flexibility, good fatigue fracture resistance, corrosion resistance, good dimensional stability, and ease of large-area integral molding, have become one of the most important structural materials in modern aerospace. The application and quantity of composite materials in aircraft have become one of the main indicators of the advancement of aircraft structures. With the continuous improvement of the use of composite materials in aircraft and the design level of composite parts, composite parts have evolved from the original conventional shapes such as "C", "L", "I", and "T" to include composite parts with closed-angle structures with up and down flanges. This places higher demands on the molding of composite materials. Currently, composite molding dies include metal molds, composite material molds, rubber molds, foam molds, plaster molds, and soluble polymer molds. Traditionally, irregularly shaped composite material parts can be manufactured using rubber shrink molding, foam, or plaster molding, and the parts can be obtained by breaking the mold after molding. However, these molds are only suitable for one or a few molding cycles, which is not conducive to mass production. Moreover, the surface precision and quality of composite parts manufactured using these molds are generally inferior to those made with metal molds. The purpose of this invention is to provide a reasonably designed and highly manufactured metal mold for forming arc ribs of a composite material with upper and lower flanged closed angle structure, while solving the problems of forming and demolding arc ribs of composite material with upper and lower flanged closed angle structure. Summary of the Invention

[0003] (a) Technical problems to be solved The technical problem to be solved by the present invention is to overcome the defects of the present invention, such as difficulty in molding complex closed-angle composite material parts, difficulty in demolding, and difficulty in ensuring the accuracy of mass production. The invention provides a metal forming fixture and corresponding forming method that is reasonably designed, easy to operate, can effectively ensure the accuracy and quality of parts, and solves the demolding problem of closed-angle structures with upper and lower flanges.

[0004] (II) Technical Solution To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a forming fixture for an arc-shaped rib of a composite material with upper and lower flanged closed angle structure, used for forming an arc-shaped rib of a composite material with upper and lower flanged closed angle structure, including an upper forming mold, a lower forming mold, a strip-shaped positioning block, and a combined positioning pin; the profile of the upper forming mold is adapted to the upper profile of the arc-shaped rib part, and the upper forming mold is provided with a first combined positioning hole and a first strip-shaped positioning groove; the profile of the lower forming mold is adapted to the lower profile of the arc-shaped rib part, the lower forming mold includes a lower forming mold body and a lower forming mold split block detachably connected to the lower forming mold body, the lower forming mold body is provided with a second combined positioning hole and a second strip-shaped positioning groove corresponding to the upper forming mold; the profile of the strip-shaped positioning block matches the first strip-shaped positioning groove and the second strip-shaped positioning groove, used to realize the lateral positioning of the upper forming mold and the lower forming mold; the combined positioning pin matches the first combined positioning hole and the second combined positioning hole, used to realize the positioning of the upper forming mold and the lower forming mold in combination. In the above technical solution, designing the lower forming mold as a combination of the lower forming mold body and separable modular blocks is the core concept for solving the demolding problem of closed-angle (θ<90°) structures with upper and lower flanges. After curing, the separable modular blocks can be removed first, thereby releasing the wrapping around the lower flange of the part and making overall demolding possible, avoiding damage to the part or mold. The combined positioning pins and strip positioning blocks effectively solve the problem of non-coplanarity of the upper and lower flanges of the part caused by the mold-closing deviation of the upper and lower forming molds. The combined positioning pins are used to quickly and accurately align the circumferential positions of the upper and lower forming molds; the strip positioning blocks are embedded in the corresponding positioning grooves of the upper and lower forming molds, providing precise lateral positioning and support. This design ensures the consistency of the relative position of the molds during each assembly, thereby guaranteeing the stability of part dimensions and surface accuracy in mass production. This solution decomposes the complex overall mold into several functional modules, allowing processes such as layup, assembly, and demolding to be performed step-by-step and in an orderly manner, reducing operational difficulty and error rate.

[0005] Preferably, the upper forming mold has a hollow structure, and the wall thickness d of the upper forming mold satisfies: 10mm ≤ d ≤ 15mm. The above technical solution, while ensuring that the upper forming mold has sufficient rigidity and strength to resist the curing pressure of the autoclave and prevent deformation, minimizes the weight of the mold by using a hollow design and limiting a reasonable wall thickness range. This facilitates the operation of the tooling during laying, transportation, and loading into the autoclave, improving work efficiency and reducing labor intensity.

[0006] Preferably, the diameter Φ of the first combined positioning hole / second combined positioning hole satisfies: 10mm≤Φ≤15mm; the width L and depth h of the first strip positioning groove / second strip positioning groove satisfy: 20mm≤L≤50mm, 10mm≤h≤15mm.

[0007] Preferably, the strip positioning block has a width of L and a thickness of h1 = h + 10 mm. This technical solution allows the strip positioning block to protrude 10 mm beyond the positioning groove. This protruding structure forms a natural "handle," allowing the operator to easily grasp, insert, and remove the positioning block by hand or tool, greatly facilitating assembly and demolding operations and improving process convenience.

[0008] Preferably, the composite arc rib with upper and lower flanges and closed angle structure includes a web and a side flange. The side flange is connected to the side of the web and surrounds the web. The side flange has a strip groove. The web divides the side flange into an upper flange and a lower flange.

[0009] Preferably, the angle between the upper flange / lower flange and the web is θ, where 60°≤θ<90°.

[0010] Preferably, the angle α between the separation surface of the lower forming mold segment and the lower forming mold body and the bottom surface of the web plate satisfies: α = θ - 5°. Even if the closed angle θ of the part is less than 90°, by making the separation surface angle α 5° smaller than θ, in the theoretical model, the segment and the inner surface of the lower flange of the part are no longer in surface contact, but rather there is a small gap. This effectively provides an effective draft angle for the segment in the demolding direction (usually perpendicular to the separation surface).

[0011] Achieving interference-free separation: During actual demolding, this 5° difference allows the split blocks to gradually disengage from the sharp-angled flanges of the parts as they move outward, without "jamming" or "scratching" the surface of the parts, thus achieving safe and damage-free demolding.

[0012] Preferably, the angle between the working surface of the first strip positioning groove / second strip positioning groove and the bottom surface of the web is θ.

[0013] Preferably, the lower molding die has a pry bar opening, the width of which is 15-20mm and the height is 5-10mm.

[0014] Secondly, the present invention also provides a molding method for manufacturing arc ribs of composite materials with upper and lower flanged closed angle structures using the above-mentioned molding tooling for forming arc ribs of composite materials with upper and lower flanged closed angle structures, comprising the following steps: S1. Lay prepreg layers on the lower forming mold to form a lower layer group, and lay prepreg layers on the upper forming mold to form an upper layer group, and pre-compact them respectively. S2. Position and combine the upper forming mold and the lower forming mold using the strip positioning block and the combination positioning pin so that the lower layer group and the upper layer group are positioned opposite each other. Then, fill the cavity area formed between the lower layer group and the upper layer group with prepreg and pre-compact it to obtain the tooling assembly. S3. Lay prepreg layers on the side of the tooling assembly to form a lateral layup group, and pre-compact it. Then remove the assembly positioning pin to obtain a preformed assembly. S4. Vacuum seal and cure the preformed component; S5. After curing, remove the strip positioning blocks in sequence, separate the lower molding mold split block from the lower molding mold body and take it out, and finally remove the formed upper and lower flange closed angle structure composite material arc rib from the upper molding mold.

[0015] (III) Beneficial Effects The above-described technical solution of the present invention has at least the following advantages: 1. In this invention, the upper and lower forming molds serve as both layup and forming molds. After the prepreg layup is completed, curing can proceed, improving the precision of component forming. By designing a separable lower forming mold block and precisely controlling its separation angle, the lower forming mold block can be removed first after curing, releasing the closed-angle area of ​​the part and making the entire demolding process possible, avoiding damage to the part or mold. Furthermore, a positioning system combining combined positioning pins and strip positioning blocks ensures accurate circumferential and lateral positioning of the upper and lower forming molds during assembly, thereby guaranteeing the surface accuracy of the part, layup alignment accuracy, and overall dimensional stability.

[0016] 2. The tooling body of the present invention is made of metal material, which is sturdy and durable, reusable, and the demolding process is standardized and reliable, making it very suitable for the mass production needs of high-quality composite material components in the aerospace field.

[0017] The tooling structure is modular, with clearly defined functions for components such as the upper mold, lower mold, split blocks, and positioning blocks. The demolding process is logically clear, and the use of pry bar openings and other designs reduces the difficulty of demolding and improves operational efficiency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is a schematic diagram of the structure of the arc-shaped rib forming tool for composite material with upper and lower flange closed angle structure provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the arc-shaped rib of the composite material with upper and lower flanged closed angle structure provided in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the ply stack structure of the arc-shaped rib of the composite material with upper and lower flange closed angle provided in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the upper molding die provided in an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the structure of the lower molding die provided in an embodiment of the present invention.

[0024] The labels for the attached figures are as follows: 1. Composite material arc-rib part with closed-angle structure and upper and lower flanges; 110. Web plate; 120. Side flange; 130. Strip groove; 140. Positioning through hole; 2. Upper forming mold; 2-1. First combined positioning hole; 2-2. First strip positioning groove; 3. Lower forming mold; 3-1. Lower forming mold split block; 3-2. Second combined positioning hole; 3-3. Second strip positioning groove; 3-4. Pry bar opening; 3-5. Separation surface; 4. Strip positioning block. Detailed Implementation

[0025] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments: like Figures 1 to 5 As shown, a preferred embodiment of the present invention provides a molding tool and molding method for arc-shaped ribs of composite materials with upper and lower flanged closed angle structures.

[0029] The tooling for forming curved ribs of composite materials with upper and lower flanges and closed angles is used to manufacture, for example, Figure 2 The illustrated composite arc-rib part 1 has a closed-angle structure with upper and lower flanges. Part 1 has an "I"-shaped cross-section, including a central web 110 and two side flanges 120. The web 110 divides the side flanges 120 into an upper flange and a lower flange, with the included angle θ between the upper flange, the lower flange, and the web 110 being 75° (satisfying 60°≤θ<90°), forming a typical closed-angle structure. The side flanges 120 may be provided with strip grooves 130, and the web 110 is provided with positioning through holes 140.

[0030] The upper and lower flange closed-angle composite material arc rib forming tooling includes an upper forming mold 2, a lower forming mold 3, a strip positioning block 4, and a combination positioning pin (not shown in the figure).

[0031] like Figure 4 As shown, the surface of the upper forming mold 2 precisely matches the upper surface of part 1 (i.e., the upper flange and part of the web surface). The upper forming mold 2 adopts an internally hollowed-out structure to reduce weight, and its wall thickness d is 12mm (within the range of 10-15mm). Near both ends of the upper forming mold 2, a first combined positioning hole 2-1 and a first strip positioning groove 2-2 are respectively machined. The diameter Φ of the positioning hole 2-1 is 12mm (within the range of 10-15mm), the width L of the strip positioning groove 2-2 is 30mm (within the range of 20-50mm), and the depth h is 12mm (within the range of 10-15mm). The angle between the working surface of the strip positioning groove 2-2 and the horizontal plane is equal to the closed angle θ of the part, i.e., 75°.

[0032] like Figure 5As shown, the surface of the lower forming mold 3 precisely matches the lower surface of part 1 (i.e., the lower flange and part of the web surface). The lower forming mold 3 consists of a lower forming mold body and a lower forming mold split block 3-1. The split block 3-1 is connected to the body through its separation surface 3-5. The angle α between the separation surface 3-5 and the horizontal plane (i.e., the bottom surface of the web 110 of the part) is designed to be 70° (i.e., α = θ - 5°). On the lower forming mold body, a second combined positioning hole 3-2 and a second strip positioning groove 3-3 corresponding to the upper forming mold 2 are machined. Their dimensions (Φ, L, h) and the working surface angle of the strip positioning groove (θ = 75°) are the same as those of the upper mold 2. On the side of the lower forming mold 3, two pry bar openings 3-4 are provided, with a width of 18mm and a height of 8mm, for inserting pry bars and other tools.

[0033] The strip positioning block 4 is a rectangular steel block with a width consistent with the width L of the strip positioning groove (30mm) and a thickness h1 = h + 10mm = 22mm. The diameter of the combined positioning pin is consistent with the diameter Φ of the combined positioning hole (12mm), and its length is slightly greater than the total depth of the positioning hole after the upper and lower molds are combined.

[0034] The upper forming mold 2, the lower forming mold 3 (including the lower forming mold split block 3-1) and the strip positioning block 4 are all made of Q235 steel plate by CNC milling, which ensures high dimensional accuracy and surface quality.

[0035] The forming method for manufacturing part 1 using the above-described tooling includes the following steps: S1. Laying down the lower and upper layers: First, on the surface of the lower forming mold 3 (including the lower forming mold segment 3-1), the prepreg is laid down according to the designed layup sequence and angle to form the lower layer group of part 1. Simultaneously, prepreg is laid down on the surface of the upper forming mold 2 to form the upper layer group. During and after the laying process, pre-compactment is performed using a scraper or rollers to remove air between layers.

[0036] S2. Combination Positioning and Cavity Filling: Insert the strip positioning block 4 into the second strip positioning groove 3-3 of the lower forming mold 3. Then align the upper forming mold 2 with the lower forming mold 3, so that the first strip positioning groove 2-2 of the upper forming mold 2 engages with the other side of the strip positioning block 4, and simultaneously align the first combination positioning hole 2-1 of the upper forming mold 2 and the second combination positioning hole 3-2 of the lower forming mold 3 with the positioning through hole 140. Insert the combination positioning pin, at which point the upper and lower forming molds achieve complete and precise positioning through the positioning pin and positioning block. Subsequently, fill the cavity formed between the positioned upper and lower ply groups (i.e., the web and flanged closed angle area of ​​the future part) with prepreg and compact it again to form a complete "I"-shaped preform.

[0037] S3. Laying Lateral Ply Groups: On the side surfaces of the assembled upper and lower molds, prepreg is laid along the end faces of the strip positioning blocks 4 to form the lateral ply groups of part 1, and pre-compacted. At this point, all the ply groups of part 1 (lower ply group, upper ply group, filler, and lateral ply group) together constitute the preform. The assembly positioning pins can now be removed because the strip positioning blocks 4 and the compacted prepreg provide sufficient lateral positioning.

[0038] S4. Curing and Molding: The entire tooling assembly with the preform is vacuum-sealed using auxiliary materials such as vacuum bags, sealing strips, and breathable felt to ensure airtightness. Then, it is placed in an autoclave and cured under heat and pressure according to the curing process curve of the selected prepreg system.

[0039] S5. Demolding: After the curing process is complete, remove the workpiece and remove auxiliary materials such as the vacuum bag. First, remove the strip positioning block 4 from the slot. Then, insert a pry bar into the pry bar opening 3-4 and gently pry it open. Utilizing the slope of the separation surface 3-5, separate and remove the lower molding die split block 3-1 from the lower molding die 3 body. After the split block 3-1 is removed, the covering of the closed corner area of ​​the lower flange of part 1 is completely released. Subsequently, the lower molding die 3 body can be easily moved downwards and removed. Finally, remove the solidified part 1 from the upper molding die 2, clean it, and the final product is obtained.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forming tooling for arc-shaped ribs of composite materials with upper and lower flanged closed angle structures, used for forming arc-shaped ribs of composite materials with upper and lower flanged closed angle structures, characterized in that, Includes upper forming mold, lower forming mold, strip positioning block and combination positioning pin; The upper forming die has a profile that is adapted to the upper profile of the arc-shaped rib part. The upper forming die is provided with a first combined positioning hole and a first strip positioning groove. The profile of the lower forming mold is adapted to the lower profile of the arc-shaped rib part. The lower forming mold includes a lower forming mold body and a lower forming mold split block detachably connected to the lower forming mold body. The lower forming mold body is provided with a second combined positioning hole and a second strip positioning groove corresponding to the upper forming mold. The surface of the strip positioning block matches the first strip positioning groove and the second strip positioning groove, and is used to achieve lateral positioning of the upper forming mold and the lower forming mold; The combined positioning pin matches the first combined positioning hole and the second combined positioning hole, and is used to position the upper forming mold and the lower forming mold in combination.

2. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 1, characterized in that, The upper forming mold has a hollow structure, and the wall thickness d of the upper forming mold satisfies: 10mm≤d≤15mm.

3. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 1, characterized in that, The diameter Φ of the first combined positioning hole / second combined positioning hole satisfies: 10mm≤Φ≤15mm; the width L and depth h of the first strip positioning groove / second strip positioning groove satisfy: 20mm≤L≤50mm, 10mm≤h≤15mm.

4. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 3, characterized in that, The strip positioning block has a width of L and a thickness of h1 = h + 10 mm.

5. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 1, characterized in that, The composite material arc rib with upper and lower flanges and closed angle structure includes a web and side flanges. The side flanges are connected to the side of the web and are arranged around the web. The side flanges are provided with strip grooves. The web divides the side flanges into upper flanges and lower flanges.

6. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 5, characterized in that, The angle between the upper / lower flange and the web is θ, where 60°≤θ<90°.

7. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 5, characterized in that, The angle α between the separation surface of the lower forming mold segment and the lower forming mold body and the bottom surface of the web plate satisfies: α = θ - 5°.

8. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 5, characterized in that, The angle between the working surface of the first strip positioning groove / second strip positioning groove and the bottom surface of the web is θ.

9. The forming tooling for the arc-shaped rib of the composite material with upper and lower flanged closed angle structure as described in claim 1, characterized in that, The lower molding die has a pry bar opening, the width of which is 15-20mm and the height is 5-10mm.

10. A molding method for manufacturing arc-shaped ribs of composite materials with upper and lower flanged closed-angle structures using the molding tooling for arc-shaped ribs of composite materials with upper and lower flanged closed-angle structures as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Lay prepreg layers on the lower forming mold to form a lower layer group, and lay prepreg layers on the upper forming mold to form an upper layer group, and pre-compact them respectively. S2. Position and combine the upper forming mold and the lower forming mold using the strip positioning block and the combination positioning pin so that the lower layer group and the upper layer group are positioned opposite each other. Then, fill the cavity area formed between the lower layer group and the upper layer group with prepreg and pre-compact it to obtain the tooling assembly. S3. Lay prepreg layers on the side of the tooling assembly to form a lateral layup group, and pre-compact it. Then remove the assembly positioning pin to obtain a preformed assembly. S4. Vacuum seal and cure the preformed component; S5. After curing, remove the strip positioning blocks in sequence, separate the lower molding mold split block from the lower molding mold body and take it out, and finally remove the formed upper and lower flange closed angle structure composite material arc rib from the upper molding mold.

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