A method for integrally forming a hollow composite material preform

Abstract

The present application relates to a kind of hollow composite material prefabricated body integrated forming method, applicable to advanced manufacturing technology field.The process of the method of the present application includes: hollow composite material prefabricated body is divided into upper panel, lower bottom plate and sandwich structure three parts, based on the guiding plate of prefabricated body structure feature design, construct guiding array, the path planning of three parts is carried out respectively, the interlacing winding of continuous yarn is completed in combination with bending winding principle, the guiding needle at the node of hollow structure is replaced with composite wire material, ensure that composite wire material fiber rod segment can support node aperture, fiber silk segment is laid on the surface of upper panel and lower bottom plate, yarn replaces peripheral guiding rod, while the upper panel and lower bottom plate are densified in Z direction.Compared with prior art, the integrated forming mode proposed in the present application can effectively reduce the debonding phenomenon at the node of sandwich structure, realize the overall near-net forming of hollow composite material sandwich panel, and improve the forming efficiency of hollow composite material panel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of advanced manufacturing technology, in particular to a method for integrally forming a hollow composite material preform. BACKGROUND

[0002] Composite materials are widely used in aerospace, rail transportation and other fields due to their lightweight, high specific strength, high specific modulus and other characteristics. Hollow composite materials, as multifunctional integrated materials, have stronger sound insulation, heat insulation, noise reduction, shock resistance and fatigue resistance without changing the structure size, and are widely used in various shell structures due to their lightweight and high efficiency.

[0003] According to the traditional processing method, the upper and lower plates and the hollow structure of the hollow composite material are woven separately, and finally bonded together. The sandwich structure is also connected by adhesive bonding of each core column cell, and the strength of the bonding part is low, and the layers are easy to peel off, which limits the overall mechanical properties of the composite material. The development of three-dimensional weaving technology of composite materials provides a new technology and idea for the integrated forming of hollow sandwich composite materials. The preform structure is changed from two-dimensional to three-dimensional, and the bearing capacity is greatly enhanced. The integrally forming method of the hollow composite material preform provided by the present application can reduce the forming process, improve the overall anti-peeling capacity, and enhance the designability of the structure. SUMMARY

[0004] The present application mainly provides a method for integrally forming a hollow composite material preform. The method effectively solves the problems of complex forming steps of hollow composite material plates and easy peeling of hollow structure nodes, in response to the requirements of three-dimensional structure hollow composite material preforms in the field of aerospace in China.

[0005] Based on the above needs, a method for integrally forming a hollow composite material preform is provided, which includes the following steps:

[0006] Step 1, analyze the preform containing hollow structure, establish a three-dimensional model according to its characteristics and size, extract the node position to complete the point array distribution of the inside and edge, and design a guide plate (1);

[0007] Step 2, divide the hollow composite material preform into upper plate (5), sandwich structure (6) and lower bottom plate (7) according to the structure, design and plan the upper and lower plate dense laying path and the hollow structure winding path, and weave with continuous fibers (4) from bottom to top according to the order of lower bottom plate-sandwich structure-upper plate;

[0008] Step 3, according to the preform shape size and hollow structure node position requirements, arrange the outer dense and inner sparse guide holes (2) on the guide plate (1) designed in a partitioned and modularized manner, and insert the guide rods (3) to obtain a guide array;

[0009] Step 4, according to the path planning of the lower bottom plate, the weaving of the lower bottom plate (7) is carried out, the fibers are Z-shaped wound according to the position of the outer layer guide rod, and in the linear traction path, the fibers in the 3n+2 and 3n+3 (n∈N) columns are S-shaped wound around the node guide rod in the Y direction, and the fibers in the 3n+1 column are linearly arranged, in the X direction, at the three rows of nodes in the middle of the guide plate and the middle row of nodes at the beginning and end of the position unit, the fibers are S-shaped wound around the node guide rod, and the rest are linearly arranged, the weaving path starts from point A, and ends at point B according to the path planning in the Y direction, and the next layer is woven according to the path planning in the X direction, and the Y direction and the X direction are sequentially laid, and every five layers are placed and pressed by a compaction plate, and the above steps are repeated to complete the forming of the lower bottom plate (7), and the fiber path ends at point A;

[0010] Step 5, according to the path planning of the hollow structure, the interlayer is woven, the fibers are introduced from point A to point C, and are eight-shaped wound according to the trajectory planning, and a single layer is laid at point D, and then is laid in reverse order, and every ten layers are placed and pressed by a compaction plate, and the above steps are repeated to complete the forming of the interlayer structure (6), and the fiber path ends at point C;

[0011] Step 6, the fibers are introduced from point C to point A, and the upper panel (5) is woven after placing a soluble core mold in the hollow position, and the path trajectory and the forming process are the same as those of the lower bottom plate, and the upper panel is formed;

[0012] Step 7, the fibers are segmented and cured to obtain a composite wire material with equal fiber wires and secondary arrangement between fiber rods, the guide rod at the node is replaced by the composite wire material, the fiber rod segment (8) is used to fill the guide rod at the node position of the hollow grid, and the fiber wire segment (9) at both ends of the fiber rod is laid on the surface of the upper panel (5) and the lower bottom plate (7) respectively;

[0013] Step 8, the outer layer dense guide rod of the upper panel (5) and the lower bottom plate (7) is replaced by using fibers, and Z-directional densification is completed by using a crochet needle, so that the upper panel and the lower bottom plate are three-dimensional woven structures;

[0014] Step 9, the core mold is dissolved, and the preforming of the hollow composite material preform is completed.

[0015] In the method, the guide array is a partition density control, the position of the outer layer dense guide hole depends on the outer shape size of the preform, and the position of the inner layer sparse guide hole depends on the node position of the hollow structure.

[0016] The method adopts regional path planning, the upper panel and the lower bottom plate are Z-shaped wound according to the distribution of the outer dense guide rod, and S-shaped winding is avoided at the node position; the interlayer part is eight-shaped wound according to the distribution of the node position guide rod.

[0017] In the method, the whole fiber is used to realize the overall connection according to the weaving sequence of the lower bottom plate-hollow interlayer-upper panel through continuous trajectory design.

[0018] In the method, the upper panel and the lower bottom plate are replaced by the whole fiber after being formed, and then the upper panel and the lower bottom plate are densely replaced in the Z direction to form a three-dimensional orthogonal structure, and a compaction plate is used for pressing at each forming height.

[0019] In the method, the hollow structure can be modularly replaced with a unit cell type to realize diversified forming of different hollow geometries, different node densities and various interlayer topological structures.

[0020] In the method, the size ratio of the composite wire fiber rod segment and the fiber wire segment is adjusted according to the structure of the preform.

[0021] The application of the above-mentioned invention has the following beneficial effects:

[0022] 1) The method of replacing the guide rod at the node by the composite wire can realize the integrated forming of the upper panel, the hollow structure and the lower bottom plate of the hollow composite preform, replace the traditional forming method of synthesizing the interlayer structure by adhesion, and reduce the forming steps of the hollow composite preform by applying the composite wire without adhesion of each unit cell; at the same time, the fiber rod segment is reserved in the node to enhance the fiber strength at the node and effectively reduce the possibility of debonding at the node of the hollow structure;

[0023] 2) The guide plate used in the method is designed according to the three-dimensional model of the hollow preform, and the near-net forming of the preform can be realized by designing the guide plate and the guide array, assisted by efficient and reasonable path planning, to improve the forming precision and forming quality and realize the overall forming of the high-precision hollow preform; at the same time, the forming efficiency is high and the cost is low, which can provide a new idea for the industrialized production and application of the hollow composite board. 3) The method of the present application can be flexibly designed according to the requirements, because the lower bottom plate, the hollow structure and the upper panel are formed in sequence, so the thickness and proportion of each part can be randomly adjusted; at the same time, the size and structure shape of the preform can be adjusted by changing the size of the guide plate and the arrangement mode of the guide hole, and the flexibility is high;

[0024] 4) The method of the present application densifies the upper plate and the lower plate in the Z direction, so that the two plates are enhanced from a general two-dimensional structure to a three-dimensional preform, greatly increasing the stability of the structure; at the same time, the preform is ensured to have a fiber volume content by stage pressuring during the forming process. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present application, a brief introduction of the drawings is given.

[0026] Figure 1 It is a structural design drawing of the guide plate.

[0027] Figure 2 It is a structural design drawing of the guide array.

[0028] Figure 3 It is a structural distribution diagram of the preform.

[0029] Figure 4 It is a path planning diagram of the upper plate and the lower plate, wherein (a) represents Y-direction odd layer laying, (b) represents X-direction odd layer laying, (c) represents odd layer XY laying, (d) represents Y-direction even layer laying, (e) represents X-direction even layer laying, and (f) represents even layer XY laying.

[0030] Figure 5 It is a path planning diagram of the hollow interlayer structure, wherein (a) represents the weaving sequence, and (b) represents the path planning.

[0031] Figure 6 It is a shape diagram of the composite wire.

[0032] Figure 7 It is a preform sample structure diagram.

[0033] In the figure: 1 - guide plate; 2 - guide hole; 3 - guide rod; 4 - continuous fiber; 5 - upper plate;

[0034] 6 - interlayer structure; 7 - lower plate; 8 - fiber rod segment; 9 - fiber wire segment; DETAILED DESCRIPTION

[0035] The present application is described in detail in combination with a specific implementation case.

[0036] Example 1

[0037] First, determine the structure size of the preform, the size of the upper plate and the lower plate is 200mmx200mmx3mm, the hollow structure is a regular hexagonal cell with a side length of 2.5mm, a three-dimensional model is established, the node position is extracted to complete the point array distribution of the interior and the edge, and the guide plate (1) is designed.

[0038] The second step involves dividing the hollow composite precast body into three parts according to its structure: the upper panel (5), the sandwich structure (6), and the lower base plate (7), as follows: Figure 3 As shown, the dense laying path of the upper and lower plates and the winding path of the hollow structure are designed and planned. The entire continuous fiber (4) is used to weave from bottom to top according to the order of the lower bottom plate-sandwich structure-upper plate.

[0039] The third step involves arranging guide holes (2) on the guide plate (1) of the modular design, based on the external dimensions of the precast body and the requirements for the location of the hollow structure nodes. Figure 1 As shown, the outer layer holes are densely distributed, while the inner layer holes are sparsely distributed. Guide rods (3) are arranged on the guide holes to obtain a guide array as shown. Figure 2 As shown;

[0040] The fourth step involves weaving the lower base plate (7) according to the path planning. The fibers are wound in a Z-shape according to the position of the outer guide bar, and wound in an S-shape around the guide bar when passing through the internal nodes in the straight traction path. The Y-direction, X-direction, and single-layer trajectory shapes are as follows: Figure 4 As shown, in the Y direction, the fibers in columns 1, 4, 7, 10, 13, 16, and 19 are arranged in a straight line, and the remaining fibers are wound around the node guide bar in an S-shape. In the X direction, the fibers in rows 3, 8, 10, 12, and 17 are arranged in a straight line, and the remaining fibers are wound around the node guide bar in an S-shape. The weaving path starts from point A, follows the path planning in the Y direction to point B, and then follows the path planning in the X direction back to point A to start weaving the next layer. The fibers are laid out in the order of the Y and X directions. Every ten layers are formed, a pressing plate is placed to apply pressure. The above steps are repeated to complete the formation of the bottom plate (7). The fiber path ends at point A.

[0041] The fifth step involves weaving the interlayer according to the path planning of the hollow structure, guiding the fibers from point A to point C, and following... Figure 5 (a) The trajectory planning is figure-eight winding, the sequence is hole 1➡2➡3➡4➡5➡6➡7➡8➡9➡10➡5➡4➡11➡12➡13➡10➡···, the single layer is laid at point D, and then laid in reverse order. Every ten layers are formed, a compaction plate is placed to pressurize, and the above steps are repeated to complete the formation of the sandwich structure (6). The fiber path ends at point c.

[0042] Step 6: Guide the fiber from point C to point A, place the soluble core mold in the hollow position and then weave the upper panel (5). Its path and forming process are the same as the lower bottom plate, and the upper panel is formed.

[0043] Step 7: The fibers are cured in sections to obtain a composite filament material with equal arrangement of fiber filaments and fiber rods, such as... Figure 6As shown, the guide rods at the node are replaced by composite wires, the guide rods at the hollow grid node position are filled with fiber rod segments (8), and the fiber wire segments (9) at both ends of the fiber rod are laid on the surface of the upper panel (5) and the lower bottom plate (7) respectively;

[0044] In the eighth step, the outer dense guide rods of the upper panel (5) and the lower bottom plate (7) are replaced by fibers, and the Z-direction densification is completed by using a crochet needle, so that the upper panel and the lower bottom plate are both three-dimensional woven structures;

[0045] In the ninth step, the preforming of the hollow composite material preform is completed, and the final structure of the core mold is shown in Figure 7 .

Claims

1. A method of integrally forming a hollow composite preform, characterized by, Comprising the following steps: Step 1, analyze the preform containing hollow structure, according to its characteristics and The size of the three-dimensional model, extraction node position to complete the internal and edge point array distribution, design guide plate (1); Step 2, the hollow composite preform is divided into three parts according to the structure, the upper panel (5), the sandwich structure (6), the lower bottom plate (7), the design of the upper and lower plate dense path and the hollow structure winding path, according to the order of the lower bottom plate-sandwich structure-upper panel, the whole continuous fiber (4) is woven from bottom to top in turn; Step 3, according to the preform size and hollow structure node position requirements, the outer dense and inner sparse guide hole (2) is arranged on the partition modular design guide plate (1), and the guide rod (3) is inserted to obtain the guide array; Step 4, according to the path planning of the lower bottom plate, the lower bottom plate (7) is woven, the fiber is Z-shaped winding according to the outer guide rod position, S-shaped winding around the guide rod in the straight line traction path, in the Y direction, the 3n+2 and 3n+3 (n∈N) column fiber is S-shaped winding around the node guide rod, the 3n+1 column fiber is linear arrangement, in the X direction, at the three rows of nodes in the guide plate middle line position unit cell and the middle row nodes at the head and tail position unit cell, the fiber is S-shaped winding around the node guide rod, the rest is linear arrangement, the weaving path starts from A point, ends at B point according to the Y direction path planning, returns to A point to start weaving the next layer according to the X direction path planning, and is placed in turn according to the Y direction and X direction. Step 5, according to the path planning of the hollow structure, the sandwich is woven, the fiber is introduced from A point to C point, and is eight-shaped winding according to the track planning, and a single layer is placed at D point, then is placed in reverse order, every ten layers are placed in the compaction plate for pressing, the above steps are repeated, the sandwich structure (6) is formed, and the fiber path ends at c point; Step 6, the fiber is introduced from C point to A point, and the upper panel (5) is woven after placing the soluble core mold in the hollow position, the path trajectory and forming process are the same as those of the lower bottom plate, and the upper panel is formed; Step 7, the fiber is cured in sections, the composite wire is obtained, the guide rod at the node is replaced by the composite wire, the guide rod in the hollow grid node position is filled by the fiber rod segment (8), and the fiber wire segment (9) at both ends of the fiber rod is placed on the surface of the upper panel (5) and the lower bottom plate (7); Step 8, the outer dense guide rod of the upper panel (5) and the lower bottom plate (7) is replaced by the fiber, and the Z direction is densified by using the crochet to make the upper panel and the lower bottom plate be three-dimensional woven structures; Step 9, the core mold is dissolved, and the preforming of the hollow composite preform is completed.

2. The method of claim 1, wherein The guide array is a partition density control, the distribution position of the outer dense guide hole depends on the size of the preform, and the position of the inner sparse guide hole depends on the node position of the hollow structure.

3. The method of claim 1, wherein The upper panel and the lower bottom plate are Z-shaped wound according to the distribution of the outer dense guide rods, and are S-shaped wound to avoid at the node position; the sandwich part is eight-shaped wound according to the distribution of the node position guide rod.

4. The method of claim 1, wherein Through continuous trajectory design, the whole fiber is used to realize the overall connection in the weaving sequence of the lower bottom plate-hollow sandwich-upper panel.

5. The method of claim 1, wherein After the upper panel and the lower bottom plate are formed, the whole fiber is used to replace the outer dense guide needle, and then the upper panel and the lower bottom plate are Z-densified to a three-dimensional orthogonal structure, and a compaction plate is used for pressing at each forming height.

6. The method of claim 1, wherein The hollow structure can be modularized to replace the unit cell type, and realize the diversification of different hollow geometries, different node densities and various sandwich topological structures.

7. The method of claim 1, wherein The size ratio of the composite wire fiber rod segment and the fiber wire segment is adjusted according to the structure of the preform.

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