Three-dimensional multi-directional variable cross-section preform and method of weaving

Abstract

The application discloses a three-dimensional multidirectional variable cross-section preform, which comprises skin layers on two sides and a core layer in the center, the skin layers are of equal-thickness and equal-width structures, the core layer is of a variable cross-section structure, the skin layers are of any one of three-dimensional four-directional to seven-directional same structures or any combination structure of three-dimensional four-directional to seven-directional structures, the core layer is of any combination structure of three-dimensional four-directional to seven-directional structures, and the core layer is composed of an equal-thickness and equal-width woven body in the center and variable cross-section non-woven bodies on two sides, and the variable cross-section is realized by layering and trimming of yarns in the length and width directions of the variable cross-section non-woven bodies; and the application further discloses a weaving method of the three-dimensional multidirectional variable cross-section preform, wherein a starting weaving cross-section is defined at one end of a main bearing direction of the product, a four-step three-dimensional multidirectional weaving process is adopted for weaving, in the weaving process, different layers of unidirectional continuous yarns are designed at a cross-section change position, and circumferential yarns are introduced in the width direction to connect different layers of fabrics into a whole, so that the whole forming is realized, the weaving efficiency and quality are improved, the process is simple, and the applicability is wide.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of three-dimensional textile preform forming, and relates to a three-dimensional multidirectional variable cross-section preform and a weaving method thereof. BACKGROUND

[0002] Three-dimensional reinforced preforms are manufactured by three-dimensional textile process technology and have a unique space interlacing structure. They are structural reinforcement skeletons of high-performance composite materials, have the characteristics of continuous fibers, integral structure, superior performance, and strong designability, and are widely used in military, aerospace, underwater weapons, and other military fields. Traditional three-dimensional preform weaving processes can all achieve the forming of equal cross-section preforms. However, in actual applications, most composite material components are not equal cross-section structural components, but variable cross-section special-shaped components with changing cross-sectional sizes along the length or width direction, such as ship pump jet rotor blades, wind power blades, airplane propeller blades, etc.

[0003] Generally, the following methods are used to achieve the forming of variable cross-section preforms: changing the number of rows or columns of yarns, such as Chinese Patent CN100491618C published on May 27, 2009, which completes the three-dimensional multidirectional integral weaving of variable cross-section preform components through the methods of yarn movement, plying, re-fining, or increasing yarns, segmentation, and re-movement; changing the rows and columns, such as Chinese Patent CN108998888B published on January 19, 2021, which completes the arrangement of new cross-sections through the mutual change of row and column components; designing connecting structures between different layer thicknesses, such as Chinese Patent CN115928313A published on April 7, 2023 and Chinese Patent CN116949645A published on October 27, 2023, which both achieve the integral forming of different layer fabrics through the methods of cross-movement or translation of yarns between different layer yarn arrays. The above methods all have the problems of frequent yarn movement, complex operation, low weaving efficiency, and poor fabric quality. SUMMARY

[0004] An object of the present application is to provide a weaving method for a three-dimensional multidirectional variable cross-section preform, which solves the problems of frequent yarn movement, complex operation, low weaving efficiency, and poor fabric quality of existing variable cross-section preform forming methods.

[0005] Another object of the present application is to provide a three-dimensional multidirectional variable cross-section preform.

[0006] The first technical solution adopted by the present application is a three-dimensional multidirectional variable cross-section preform, which includes skin layers on both sides and a core layer in the center. The skin layers have an equal thickness and equal width structure, and the core layer has a variable cross-section structure. The skin layers have any one of the same structures of three-dimensional four-way to seven-way or any combination of three-dimensional four-way to seven-way structures, and the core layer has any combination of three-dimensional four-way to seven-way structures.

[0007] The core layer is composed of a central equal-thickness and equal-width braided body and two sides of variable cross-section non-braided bodies, and the variable cross-section is realized by layering and trimming of the yarns in the length and width directions of the variable cross-section non-braided bodies.

[0008] The second technical solution of the application is a three-dimensional multi-directional variable cross-section preform three-dimensional braiding method, which comprises taking one end of the product main load-bearing direction as the starting braiding cross-section, adopting a four-step three-dimensional multi-directional braiding process for braiding, in the braiding process, different layers of unidirectional continuous yarns are designed at the cross-section change position, and the width direction is introduced into the circumferential yarn to connect the different layers of fabrics into one body to realize overall forming.

[0009] The method comprises the following steps:

[0010] Step 1, according to the product structure and performance requirements, the thickness and braiding structure of the preform skin layer and core layer braided body are designed;

[0011] Step 2, taking the product main load-bearing direction as the braiding direction, selecting the thickest end of the cross-section as the starting braiding surface, and determining the braiding parameters of the preform;

[0012] Step 3, according to the cross-sectional area change rate, the cross-section is divided along the braiding direction, the cross-sections with the same cross-sectional area change rate are combined, and the variable cross-section position is determined;

[0013] Step 4, yarn arrangement, the skin layer and the core layer braided body are arranged in the form of rows and columns on the braiding machine chassis according to the four-step three-dimensional braiding method and the braiding parameters of the preform, the yarns include braiding yarns and shaft yarns, wherein the main body yarn array is arranged on the corresponding yarn carrier of the three-dimensional braiding machine chassis in the form of rows and columns, and the braiding yarns are arranged as edge yarns at intervals around the main body yarn array, the number of yarns in each row and each column remains the same, and the variable cross-section non-braided body of the core layer is arranged in the form of rows and columns on a separate creel;

[0014] Step 5, according to the four-step three-dimensional braiding process, the skin layer and the core layer braided body are braided, when braiding to the cross-section change position, the circumferential yarns are introduced on the side of the skin layer close to the non-braided body of the core layer and the side of the non-braided body of the core layer close to the braided body, so that different layers are connected into one body, and the unidirectional yarns are trimmed in the form of beveling at the transition section according to the transition size, realizing variable cross-section forming;

[0015] Step 6, repeat step 5, and accompany with the tightening movement of the weaving port, finally obtain a complete three-dimensional multi-directional variable cross-section preform.

[0016] In step 1, the thickness and weaving structure of the preform skin layer and core layer are designed according to the product structure and performance requirements, the product structure includes product length, width and thickness, and the product performance includes product strength and stiffness, for the product with small thickness and low strength and stiffness requirements, three-dimensional four-directional or three-dimensional five-directional weaving structure is adopted, and for the product with large thickness and high strength and stiffness requirements, three-dimensional six-directional or three-dimensional seven-directional weaving structure is adopted.

[0017] In step 2, the weaving parameters of the preform include total yarn count, row and column number of yarns, repeat height and total cycle number.

[0018] In step 5, the circumferential yarns are introduced on the side of the skin layer close to the non-woven body of the core layer and the side of the non-woven body of the core layer close to the woven body, and every two introduced circumferential yarns are in an interlaced binding mode.

[0019] The core layer woven body is an equal-thickness and equal-width woven body in the center of the core layer, and the core layer non-woven body is a variable cross-section non-woven body on both sides of the core layer.

[0020] The beneficial effects of the present application are as follows:

[0021] (1) The three-dimensional multi-directional variable cross-section preform adopts a sandwich-like structure, including two skin layers on both sides and a core layer in the center, the skin layer is an equal-thickness and equal-width structure, the core layer is a variable cross-section structure, the core layer is composed of an equal-thickness and equal-width woven body in the center and variable cross-section non-woven bodies on both sides, the center of the skin layer and the core layer both adopt excellent three-dimensional woven structures, the skin layer and the core layer are effectively connected as a whole, and finally form a three-dimensional multi-directional overall reinforcing structure, which ensures the overall strength of the product;

[0022] (2) The four-step three-dimensional multi-directional weaving process is adopted, the non-woven unidirectional yarns on the outer side of the core layer are trimmed and shaped according to the cross-section change rule, the variable cross-section forming of the preform in different directions is realized, the method is simple in process and widely applicable, and can realize one-time overall forming of the variable cross-section preform, thereby improving the weaving efficiency and quality. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the three-dimensional multi-directional variable cross-section preform of the present application;

[0024] Figure 2 is a length direction variable cross-section forming schematic diagram of the three-dimensional multi-directional variable cross-section preform of the present application;

[0025] Figure 3 is a width direction variable cross-section forming schematic diagram of the three-dimensional multi-directional variable cross-section preform of the present application;

[0026] Figure 4 is a schematic diagram of the connection mode of different layers in the three-dimensional multi-directional variable cross-section preform of the present application.

[0027] In the figure, 1. skin layer, 2. core layer, 3. cross-section change, 4. circumferential yarn, 21. equal-thickness and equal-width woven body, 22. variable cross-section non-woven body. DETAILED DESCRIPTION

[0028] The application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The three-dimensional multi-directional variable cross-section preform of the application, with reference to Figure 1 , comprises a skin layer 1 on both sides and a core layer 2 in the center, the skin layer 1 is of an equal-thickness and equal-width structure, the core layer 2 is of a variable cross-section structure, the skin layer 1 is of any one of a three-dimensional four-directional to seven-directional structure or any combination of a three-dimensional four-directional to seven-directional structure, the core layer 2 is of any combination of a three-dimensional four-directional to seven-directional structure, the core layer 2 is composed of an equal-thickness and equal-width woven body 21 in the center and variable cross-section non-woven bodies 22 on both sides, and the variable cross-section is realized by layering and trimming the yarns in the length and width directions of the variable cross-section non-woven bodies 22.

[0030] The three-dimensional weaving method of the three-dimensional multi-directional variable cross-section preform of the application, comprising the following steps:

[0031] Step 1: design the thickness and weaving structure of the preform skin layer 1 and core layer 2 woven body according to the product structure and performance requirements, the core layer 2 woven body is the equal-thickness and equal-width woven body 21 in the center of the core layer 2, the product structure includes the length, width and thickness of the product, and the product performance includes the strength and stiffness of the product, for a product with smaller thickness and lower strength and stiffness requirements, a three-dimensional four-directional or three-dimensional five-directional weaving structure is adopted, and for a product with larger thickness and higher strength and stiffness requirements, a three-dimensional six-directional or three-dimensional seven-directional weaving structure is adopted;

[0032] Step 2: take the main load-bearing direction of the product as the weaving direction, select the thickest end of the cross-section as the starting weaving surface, and determine the weaving parameters of the preform, the weaving parameters of the preform include the total number of yarns, the number of rows and columns of the yarn arrangement, the repeat height and the total number of cycles.

[0033] Step 3: divide the cross-section according to the cross-sectional area change rate along the weaving direction, combine the cross-sections with the same cross-sectional area change rate, and determine the variable cross-section position;

[0034] Step 4: arrange the yarns, the skin layer 1 and the core layer 2 woven body are arranged in a row-column form on the weaving machine chassis according to the four-step three-dimensional weaving method and the weaving parameters of the preform, the yarns include weaving yarns and shaft yarns, wherein the main yarn array is arranged on the corresponding yarn carrier of the three-dimensional weaving machine chassis in a row-column form, the weaving yarns are arranged as edge yarns at intervals around the main yarn array, the number of yarns in each row and each column remains the same, and the variable cross-section non-woven body 22 of the core layer is arranged in a row-column form on a separate creel;

[0035] Step 5, with reference to Figure 2 and Figure 3The skin layer 1 and the core layer 2 are woven by a four-step three-dimensional weaving process. When weaving reaches the cross-section change 3, the circumferential yarn 4 is introduced on the side of the skin layer 1 close to the non-woven body of the core layer 2 and the side of the non-woven body of the core layer 2 close to the woven body, so that the different layers are connected into one body. The unidirectional yarn is trimmed in a beveled cut manner according to the transition size at the cross-section transition section, so as to realize the variable cross-section forming. The circumferential yarns introduced every two times are in an interlaced binding mode, as shown in Figure 4 .

[0036] Step 6, repeat step 5, and finally obtain a complete three-dimensional multi-directional variable cross-section preform.

[0037] Example 1

[0038] A weaving method of a three-dimensional multi-directional variable cross-section preform, the preform being a marine pump jet rotor blade, the main bearing direction being along the length direction of the blade, the length of the blade being 90mm, the width being 50mm, and the thickness being 12mm. The weaving method specifically includes the following steps:

[0039] Step 1, according to the product structure and performance requirements, the thickness and weaving structure of the preform skin layer 1 and core layer 2 woven body are designed. The preform has low strength and stiffness requirements, so the skin layer is designed as a three-dimensional four-directional structure, and the core layer is designed as a three-dimensional five-directional structure. The thickness of the skin layer woven body is 1.5mm, the thickness of the core layer equal-thickness equal-width woven body is 5mm, and the rest is a variable cross-section non-woven body.

[0040] Step 2, taking the product main bearing direction as the weaving direction, selecting the thickest end of the cross-section as the starting weaving surface, and determining the weaving parameters of the preform. The total number of yarns is 750, the skin layer row 1 has 62 columns, the repeat height is 4mm, and the total number of cycles is 23. The core layer woven body (i.e. equal-thickness equal-width woven body) has 4 rows and 62 columns, the repeat height is 5mm, and the total number of cycles is 23. The core layer non-woven body (i.e. variable cross-section non-woven body) has 3 rows and 62 columns.

[0041] Step 3, according to the cross-sectional area change rate, the cross-section is divided along the weaving direction, the cross-sections with the same cross-sectional area change rate are combined, and the variable cross-section position is determined. In this embodiment, there are 3 variable cross-section positions in the length direction of the preform, and 2 variable cross-section positions in the width direction.

[0042] Step 4, yarn arrangement, the skin layer 1 and the core layer 2 woven body are arranged on the weaving machine base in the form of rows and columns according to the four-step three-dimensional weaving method and the weaving parameters of the preform. The yarns include weaving yarns and shaft yarns. The main array yarns are arranged on the corresponding yarn carriers of the three-dimensional weaving machine base in the form of rows and columns. The weaving yarns are arranged as edge yarns around the main array yarns. The number of yarns in each row and each column remains the same. The variable cross-section non-woven body of the core layer is arranged in the form of rows and columns on a separate yarn disc.

[0043] Step 5, the skin layer and the core layer are woven according to the four-step three-dimensional weaving process. When weaving to the cross-section change, the circumferential yarns are introduced on the side of the skin layer close to the core layer non-woven body and the side of the core layer non-woven body close to the woven body, and the density is 20 mm, so that the different layers are connected into one body, and the unidirectional yarns are trimmed in a beveled cut manner according to the transition size at the cross-section transition section to realize the variable cross-section forming. Every two introduced circumferential yarns are in an interlaced binding mode;

[0044] Step 6, repeat step 5, pass through 23 machine cycles and accompany the weaving port tightening movement, and finally obtain a complete three-dimensional multi-directional variable cross-section preform.

[0045] Example 2

[0046] A weaving method of a three-dimensional multi-directional variable cross-section preform, the preform is a marine pump jet rotor blade, the main bearing direction is along the length direction of the blade, the length of the blade is 100 mm, the width is 120 mm, and the thickness is 22 mm, and the weaving method specifically includes the following steps:

[0047] Step 1, the thickness and weaving structure of the skin layer 1 and the core layer 2 woven body of the preform are designed according to the product structure and performance requirements. The preform has relatively low requirements for strength and stiffness, so the skin layer is designed as a three-dimensional four-directional structure, the core layer is designed as a three-dimensional five-directional structure, the thickness of the skin layer woven body is 3 mm, the thickness of the equal-thickness and equal-width woven body of the core layer is 6 mm, and the rest is a variable cross-section non-woven body;

[0048] Step 2, the weaving direction is the main bearing direction of the product, the thickest end of the cross section is selected as the starting weaving surface, the weaving parameters of the preform are determined, the total number of yarns is 3300, the skin layer has 2 rows of 150 columns of main yarn arrays with a stitch height of 5 mm, the total cycle number is 20; the equal-thickness and equal-width woven body has 4 rows of 150 columns of main arrays with a stitch height of 5 mm, and the total cycle number is 20; the variable cross-section non-woven body has 7 rows of 150 columns;

[0049] Step 3, the cross section is divided according to the cross-sectional area change rate, the cross sections with the same cross-sectional area change rate are combined, and the variable cross-section positions are determined. In this embodiment, there are 4 variable cross-section positions in the length direction of the preform, and there are 2 variable cross-section positions in the width direction of the preform;

[0050] Step 4, the yarns are arranged, the skin layer and the core layer woven body are woven according to the four-step three-dimensional weaving method, the yarns are arranged in the form of rows and columns on the weaving machine base according to the weaving parameters of the preform, and the yarns include weaving yarns and shaft yarns. The main array yarns are arranged on the corresponding yarn carriers of the three-dimensional weaving machine base in the form of rows and columns, and the weaving yarns are arranged as edge yarns around the main yarn array. The number of yarns in each row and each column remains the same. The variable cross-section non-woven body of the core layer is arranged in the form of rows and columns on a separate yarn disc;

[0051] Step 5, the skin layer and the core layer are woven according to the four-step three-dimensional weaving process. When weaving to the cross-section change, the circumferential yarns are introduced on the side of the skin layer close to the core layer non-woven body and the side of the core layer non-woven body close to the woven body, and the density is 30 mm, so that the different layers are connected into one body, and the unidirectional yarns are trimmed in a beveled cut manner according to the transition size at the cross-section transition section to realize the variable cross-section forming. Every two introduced circumferential yarns are in an interlaced binding mode;

[0052] Step 6, repeat step 5, pass through 20 machine cycles and accompany the weaving port tightening movement, and finally obtain the complete three-dimensional multi-directional variable cross-section preform.

[0053] Example 3

[0054] A weaving method of a three-dimensional multi-directional variable cross-section preform, the preform is a boat pump jet rotor blade, the main bearing direction is along the length direction of the blade, the length of the blade is 1000 mm, the width is 600 mm, and the thickness is 50 mm, and the weaving method specifically includes the following steps:

[0055] Step 1, the thickness and weaving structure of the preform skin layer 1 and the core layer 2 woven body are designed according to the product structure and performance requirements. The preform has high requirements for strength and stiffness, so the skin layer is designed as a three-dimensional six-directional structure, the core layer is designed as a three-dimensional seven-directional structure, the thickness of the skin layer woven body is 3 mm, the thickness of the equal-thickness and equal-width woven body of the core layer is 20 mm, and the rest is a variable cross-section non-woven body;

[0056] Step 2, the product main bearing direction is selected as the weaving direction, the thickest end of the cross section is selected as the starting weaving surface, the weaving parameters of the preform are determined, the total number of yarns is 37500, the skin layer row yarn main array is 2 rows and 500 columns, the repeat height is 5 mm, the total cycle number is 200; the equal-thickness and equal-width woven body main array is 14 rows and 500 columns, the repeat height is 8 mm, and the total cycle number is 125; the variable cross-section non-woven body is 17 rows and 500 columns;

[0057] Step 3, the cross section is divided according to the cross-sectional area change rate along the weaving direction, the cross sections with the same cross-sectional area change rate are combined, and the variable cross-section position is determined. In this embodiment, there are 30 variable cross-section positions in the length direction of the preform, and there are 8 variable cross-section positions in the width direction;

[0058] Step 4, the yarns are arranged, the skin layer and the core layer woven body are woven according to the four-step three-dimensional weaving method, the yarns are arranged in the form of rows and columns on the weaving machine base plate according to the weaving parameters of the preform, and the yarns include weaving yarns and shaft yarns. The main array yarns are arranged on the corresponding yarn carriers of the three-dimensional weaving machine base plate in the form of rows and columns, and the weaving yarns are arranged as edge yarns around the main yarn array. The number of yarns in each row and each column remains the same. The variable cross-section non-woven body of the core layer is arranged in the form of rows and columns on a separate yarn disc;

[0059] Step 5, according to the four-step three-dimensional weaving process, the skin layer and the core layer are woven into a woven body, when weaving to the cross-section transition, the skin layer is introduced with a circumferential yarn on the side close to the non-woven core layer and the non-woven core layer is introduced with a circumferential yarn on the side close to the woven body, the density is 100 mm, so that the different layers are connected into one body, and the unidirectional yarn is trimmed in a beveled cut way according to the transition size at the cross-section transition section, so as to realize the variable cross-section forming, and every two introduced circumferential yarns are in an interlaced binding mode;

[0060] Step 6, repeat step 5, pass through 200 machine cycles and accompany with the weaving port tightening movement, and finally obtain a complete three-dimensional multi-directional variable cross-section preform.

Claims

1. A three-dimensional braiding method of a three-dimensional multi- variable cross-section preform, characterized by, The application relates to a three-dimensional multi-directional variable cross-section preform, which comprises a variable cross-section preform body and a core layer (2). The application relates to a three-dimensional multi-directional variable cross-section preform, which comprises a variable cross-section preform body and a core layer (2). Step 1: according to the product structure and performance requirements, the thickness and weaving structure of the preform skin layer (1) and the core layer (2) are designed. Step 2: the thickest cross-section of the product is selected as the starting weaving surface, and the weaving parameters of the preform are determined, including the total number of yarns, the row and column number of the yarns, the repeat height and the total number of cycles. Step 3: the cross-section is divided according to the cross-section area change rate, and the cross-sections with the same cross-section area change rate are combined to determine the variable cross-section position. Step 4: the yarns are arranged, the skin layer (1) and the core layer (2) are arranged in the form of rows and columns on the weaving machine base according to the four-step three-dimensional weaving method and the weaving parameters of the preform, the yarns include weaving yarns and shaft yarns, the main yarn array is arranged on the corresponding yarn carrier of the three-dimensional weaving machine base in the form of rows and columns, the weaving yarns are arranged as the edge yarns at intervals around the main yarn array, the number of yarns in each row and each column is kept the same, and the variable cross-section non-weaving body (22) of the core layer is arranged on a separate yarn disc in the form of rows and columns. Step 5: the skin layer (1) and the core layer (2) are woven according to the four-step three-dimensional weaving process, when the weaving reaches the variable cross-section position (3), the circumferential yarns (4) are introduced on the side of the skin layer (1) close to the non-weaving body of the core layer (2) and the side of the non-weaving body of the core layer (2) close to the weaving body, so that the different layers are combined into one, and the unidirectional yarns are trimmed in the form of oblique shearing at the transition section according to the transition size, so that the variable cross-section is formed, and the circumferential yarns (4) introduced every two times are in the interlaced binding mode. Step 6: step 5 is repeated, and the weaving port is tightened, and finally the complete three-dimensional multi-directional variable cross-section preform is obtained.

2. The weaving method of a three-dimensional multi-directional variable cross-section preform according to claim 1, characterized in that, In step 1, the thickness and weaving structure of the preform skin layer (1) and the core layer (2) are designed according to the product structure and performance requirements, the product structure includes the product length, width and thickness, and the product performance includes the product strength and rigidity, for the product with small thickness and low strength and rigidity requirements, a three-dimensional four-directional or three-dimensional five-directional weaving structure is adopted, and for the product with large thickness and high strength and rigidity requirements, a three-dimensional six-directional or three-dimensional seven-directional weaving structure is adopted.

3. The weaving method of a three-dimensional multi-directional variable cross-section preform according to claim 1, characterized in that, The core layer (2) weaving body is an equal-thickness and equal-width weaving body (21) in the center of the core layer (2), and the core layer (2) non-weaving body is a variable cross-section non-weaving body (22) on both sides of the core layer (2).

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