Three-dimensional braiding method with variable bend preform

Abstract

The application discloses a three-dimensional weaving method of a preform with a variable bending structure, and the method is characterized in that: taking one end of a main bearing direction of a product as a starting weaving section, weaving is performed according to a four-step three-dimensional multi-directional weaving process, in the weaving process, different partition asynchronous weaving is designed at a structure variable bending position, and a tool is used to lift a weaving port to a horizontal state to realize variable bending, after the above continuous weaving operation, a whole three-dimensional preform with a variable bending shape is formed. The three-dimensional weaving method of the preform with the variable bending structure disclosed by the application solves the problem that the prior art cannot realize continuous penetration of fibers in a main bearing direction, and the whole strength obviously decays, and can realize integrated weaving and forming of a preform with different angle bending structures.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite preform forming method, and particularly relates to a three-dimensional weaving method of a preform with a variable bending structure. BACKGROUND

[0002] As a reinforcing body of composite materials, the three-dimensional woven preform has the advantages of good structural integrity and flexible structural design. Currently, the composite materials formed by combining the three-dimensional woven preform with high-performance resin have been widely applied to the main load-bearing components of advanced equipment in the fields of military industry, aerospace, etc.

[0003] The propeller is a key power mechanical component on military or civilian ships, and the blade part is the main component that determines the stability of the entire propeller power. The current fiber-reinforced composite propeller basically adopts a two-dimensional laminated structure preform as a reinforcing body, and this forming method can meet the needs of propeller shock absorption and noise reduction. However, most of the blades have irregular shapes and generally have complex characteristics of different degrees of bending from the blade root to the blade tip. The laminated process needs to cut and trim the material sheet at the bending part of the blade, resulting in discontinuous fibers and significantly reduced overall strength of the blade, so it is difficult to meet the relatively harsh working conditions of ships. SUMMARY

[0004] The purpose of the present application is to provide a three-dimensional weaving method of a preform with a variable bending structure, which solves the problem that the existing technology cannot realize continuous fibers in the main load-bearing direction and the overall strength is significantly attenuated, and can realize the integrated weaving forming of a preform with different angle bending structures.

[0005] The technical solution adopted by the present application is as follows: the three-dimensional weaving method of a preform with a variable bending structure takes one end of the main load-bearing direction of the preform as the starting weaving section, and weaves according to the four-step three-dimensional multi-directional weaving process. In the weaving process, the variable bending part is designed to be woven in different zones at different times, and a tool is used to lift the weaving port to a horizontal state to realize the variable bending. After the above continuous weaving operation, an integrated three-dimensional preform with a variable bending shape is formed.

[0006] The technical solution adopted by the present application has the following characteristics:

[0007] Further, the three-dimensional weaving method of a preform with a variable bending structure is implemented according to the following steps:

[0008] Step 1: design the three-dimensional weaving structure of the preform according to the performance requirements of the product;

[0009] Step 2: determine the weaving direction and weaving parameters: take the main load-bearing direction of the preform as the main weaving direction, select the end part with a large cross-sectional thickness as the starting weaving section, and design the weaving parameters of the preform;

[0010] Step 3, determining the bending reference surface of the preform and the boundary of the asynchronous weaving area: taking the cross section at the starting point of the bending arc length as the pre-bending cross section, and the midpoint cross section as the bending reference cross section; taking the pre-bending cross section as the starting boundary of the asynchronous weaving area, and the bending reference cross section as the ending boundary of the asynchronous weaving area;

[0011] Step 4, weaving area division at the bending position: dividing the asynchronous weaving area into multiple cycles according to the designed stitch height parallel to the pre-bending cross section, and the intersection point of the cycle line and the ending boundary of the asynchronous weaving area being the partition point of the weaving area at the bending position;

[0012] Step 5, yarn arrangement: arranging the yarns on the weaving machine chassis according to the four-step three-dimensional weaving method.

[0013] Step 6, four-step weaving: weaving using the 1x1 four-step three-dimensional weaving process;

[0014] Step 7, bending structure forming: when weaving to the weaving area at the bending position, re-arranging the yarn array according to the designed partition, and controlling the operation of the yarn carrier to complete the weaving of different partitions;

[0015] Step 8, repeating steps 6 and 7, and accompanying the tightening movement, to finally obtain a complete three-dimensional preform with a bending shape.

[0016] Further, the three-dimensional weaving structure of the preform in step 1 is any one of three-dimensional four-way, five-way, six-way or seven-way.

[0017] Further, the weaving parameters in step 2 include the total number of yarns, the number of rows and columns of yarn arrangement, the stitch height, and the number of cycles.

[0018] Further, the yarn arrangement method in step 5 is specifically to fix one end of the yarn to a yarn hanging device above the three-dimensional weaving machine, and the other end is hung on the yarn carrier of the three-dimensional weaving machine chassis through a tension line system; the yarns include weaving yarns and shaft yarns, which are arranged in an array of rows and columns on the weaving machine chassis, wherein the main body of the yarn array is arranged on the corresponding yarn carrier of the three-dimensional weaving machine chassis according to the row and column arrangement, and the weaving yarns arranged around the main yarn array serve as the edge yarns, and the number of yarns in each row and each column remains the same.

[0019] Further, the specific operation steps of step 6 are as follows:

[0020] Step 6.1, the weaving yarn carrier in the adjacent row moves horizontally left or right along the row direction track by one position of the weaving yarn carrier together with the shaft yarn carrier of the row;

[0021] Step 6.2, the weaving yarn carrier in the adjacent column moves vertically up or down along the column direction track by one position of the weaving yarn carrier;

[0022] Step 6.3, the weft yarn carriers in the adjacent row move horizontally left or right along the row by one weft yarn carrier position in the track direction, opposite to the movement direction of step 6.1, together with the axial yarn carriers of the row;

[0023] Step 6.4, the weft yarn carriers in the adjacent column move alternately vertically up or down along the column by one weft yarn carrier position in the track direction, opposite to the movement direction of step 6.2; at this time, the yarn carriers all return to the initial positions, completing one movement cycle.

[0024] Further, step 7 is specifically operated as follows: the weft yarn moving operation is performed once every half cycle at the same height to realize the connection of different partitions, and the weft yarn moving operation cannot change the four-step movement rule; the cycle number of each partition is different, so that the stepwise fabric along the direction perpendicular to the weaving direction is finally formed, the forming of the weaving area of the variable bending part is realized, at the variable bending reference surface, the fabric is lifted to the horizontal by using a tool, and the formed fabric is fixed, and the synchronous weaving is continued.

[0025] The beneficial effects of the present application are:

[0026] (1) The three-dimensional weaving method of the preformed part with variable bending structure of the present application can realize the overall weaving and forming of the preformed part with variable bending structure of different angles and different directions, effectively solving the problem that the laminating process cannot realize the continuous penetration of fibers in the main bearing direction, and the overall strength decays obviously.

[0027] (2) The three-dimensional weaving method of the preformed part with variable bending structure of the present application adopts continuous three-dimensional weaving technology, realizes the one-time forming of the preformed body with variable bending complex structure by ingeniously designing the different step weaving of different partitions, and has simple process mode and wide applicability, which can greatly reduce the production cost.

[0028] (3) The three-dimensional weaving method of the preformed part with variable bending structure of the present application adopts continuous weaving of high-performance fibers to form a three-dimensional preformed body, which can greatly reduce the weight of the product. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic view of the pre-bending cross section and the variable bending reference cross section of the preformed part with variable bending structure of the present application;

[0030] Figure 2 is a schematic view of the weaving area division at the variable bending part of the preformed part with variable bending structure of the present application;

[0031] Figure 3 is a schematic view of the stepwise fabric formed by the different step weaving areas of the preformed part with variable bending structure of the present application;

[0032] Figure 4is a schematic diagram of a preform with a variable bending structure according to the present application, which realizes one-time variable bending;

[0033] Figure 5 is a schematic diagram of a preform with a variable bending structure according to the present application, which realizes one-time variable bending;

[0034] Figure 6 is a schematic diagram of a preform with a variable bending structure according to the present application, which realizes one-time variable bending;

[0035] Figure 7 is a schematic diagram of a preform with a variable bending structure according to the present application, which realizes one-time variable bending.

[0036] In the figure, 1 is a pre-bending cross section, 2 is a variable bending reference cross section, 3 is a pre-variable bending step-shaped weaving port, 4 is a post-variable bending horizontal weaving port, 5 is a pre-variable bending fabric state, and 6 is a post-variable bending fabric state. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be described in detail below in combination with the drawings and specific embodiments.

[0038] The present application provides a three-dimensional weaving method of a preform with a variable bending structure. First, one end of the product in the main load-bearing direction is taken as the starting weaving cross section, and weaving is performed according to a four-step three-dimensional multi-directional weaving process. In the weaving process, different step weaving is designed in the variable bending area, and a tool is used to lift the weaving port to a horizontal state to realize variable bending. After the above continuous weaving operation, a three-dimensional preform with a variable bending shape is formed.

[0039] Specifically, the preform with a variable bending shape weaving process includes the following steps:

[0040] Step 1: Design the three-dimensional weaving structure of the preform according to the performance requirements of the product; three-dimensional four-directional, five-directional, six-directional, and seven-directional are all available;

[0041] Step 2: Determine the weaving direction and weaving parameters; take the main load-bearing direction of the product as the main weaving direction, select the end with a large cross-sectional thickness as the starting weaving cross section, and design the weaving parameters of the preform; including the total number of yarns, the number of rows and columns of the yarns, the repeat height, and the number of cycles;

[0042] Step 3: Determine the variable bending reference surface and the different step weaving area boundary; take the arc length starting cross section of the variable bending as the pre-bending cross section, and the midpoint cross section as the variable bending reference cross section; take the pre-bending cross section as the starting boundary of the different step weaving area, and take the variable bending reference cross section as the end boundary of the different step weaving area;

[0043] For example, Figure 1As shown, the arc length starting cross section is the pre-bending cross section 1 (the starting boundary of the asynchronous weaving area), and the arc length midpoint cross section is the variable-bending reference cross section 2 (the ending boundary of the asynchronous weaving area); the pre-bending cross section 1 is taken as the starting boundary of the asynchronous weaving area, and the variable-bending reference cross section 2 is taken as the ending boundary of the asynchronous weaving area;

[0044] Step 4, division of the variable-bending weaving area; as shown, Figure 2 As shown, the asynchronous weaving area is divided into multiple cycles A, B, C, D, E, F, G, … according to the designed repeat height and parallel to the pre-bending cross section, and the intersection point of the cycle line and the ending boundary of the asynchronous weaving area is the variable-bending weaving area division point a, b, c.

[0045] Step 5, yarn arrangement; the yarns are arranged on the knitting machine chassis in a four-step three-dimensional weaving manner, specifically, one end of the yarns is fixed on the yarn hanging device above the three-dimensional knitting machine, and the other end is hung on the yarn carrier of the three-dimensional knitting machine chassis through the tension line system; the yarns include knitting yarns and shaft yarns, which are arranged in a row-column array on the knitting machine chassis, wherein the main body of the yarn array is arranged on the corresponding yarn carrier of the three-dimensional knitting machine chassis according to the row-column arrangement, and the knitting yarns arranged around the main body of the yarn array are used as the edge yarns, and the number of yarns in each row and each column remains the same.

[0046] Step 6, four-step knitting; 1×1 four-step three-dimensional weaving process is adopted for knitting; the specific operation steps are as follows:

[0047] Step 6.1, the knitting yarn carriers in the adjacent rows move horizontally left or right along the row direction by one knitting yarn carrier position alternately together with the shaft yarn carriers in the row;

[0048] Step 6.2, the knitting yarn carriers in the adjacent columns move vertically up or down along the column direction by one knitting yarn carrier position alternately;

[0049] Step 6.3, the knitting yarn carriers in the adjacent rows move horizontally left or right along the row direction by one knitting yarn carrier position alternately together with the shaft yarn carriers in the row in the opposite direction of step 6.1;

[0050] Step 6.4, the knitting yarn carriers in the adjacent columns move vertically up or down along the column direction by one knitting yarn carrier position alternately in the opposite direction of step 6.2; at this time, the yarn carriers all return to the initial position, and one movement cycle is completed;

[0051] Step 7, bending structure forming; as shown, Figure 3As shown, when the yarn array is partitioned and rethreaded according to the designed partitioned areas 1, 2, 3, 4, … when being knitted to the bending area, the carrier operation is controlled to complete the knitting of different partitioned areas; the yarn shifting operation is performed once every half cycle at the same height to realize the connection of different partitioned areas, and the yarn shifting operation cannot change the four-step movement rule; the number of cycles of each partitioned area is different, and finally a stepped fabric along the perpendicular direction of the knitting direction is formed to realize the forming of the fabric in the bending area; as shown, Figure 4 As shown, at the bending reference section 2, the stepped fabric mouth 3 before the bending is lifted to the horizontal fabric mouth 4 after the bending by using a tool, the fabric state 5 before the bending is changed to the fabric state 6 after the bending, and the formed fabric is fixed, and the synchronous knitting is continued;

[0052] Step 8, repeat steps 6 and 7, and finally obtain a complete three-dimensional preform with a bending shape.

[0053] The technical scheme of the present application is further illustrated by examples and drawings.

[0054] Example 1

[0055] A preform with a bending structure is processed by using the three-dimensional knitting method of the preform with a bending structure according to the present application, as shown, Figure 5 The preform is a propeller blade for a ship, and the length direction of the blade is the main bearing direction, the length of the blade is 100 mm, the width is 60 mm, and the thickness is 15 mm;

[0056] According to the performance requirements of the product, the preform is designed to have a three-dimensional five-directional structure, the total number of yarns is 322, the main array of the rethreaded yarns is 7 rows and 42 columns, the repeat height is 4 mm, and the total number of cycles is 25;

[0057] There are three bending positions in the blade model, and the pre-bending cross sections are A-11, A-12, and A-13, and the bending reference surfaces are A-21, A-22, and A-23; the bending areas A-11-A-21, A-12-A-22, and A-13-A-23 are partitioned, and different step knitting areas are divided into three cycles, four cycles, and five cycles according to the 4 mm repeat height, the repeat line and the end boundary A-21, A-22, and A-23 form one intersection, two intersections, and three intersections, respectively;

[0058] Weaving begins with the leaf root as the starting section. When weaving reaches the bending area A-11-A-21, A-12-A-22, A-13-A-23, the yarn array is re-arranged in sections. The yarn carrier is controlled to complete the weaving of different sections. At the bending reference planes A-21, A-22, and A-23, a tool is used to lift the stepped weaving opening 3 before bending to the horizontal weaving opening 4 after bending, fix the formed fabric, and continue synchronous weaving.

[0059] After 25 machine cycles accompanied by tightening motion, a complete three-dimensional precast body with a bending shape is finally obtained.

[0060] Example 2

[0061] The three-dimensional weaving method of the present invention for preformed parts with variable bending structures is used to process another preformed part with a variable bending structure in the same direction, such as... Figure 6 As shown, this component is another type of marine propeller blade, with the main load-bearing direction along the blade length. The blade is 90mm long, 50mm wide, and 12mm thick.

[0062] Based on the product's performance requirements, the preform is designed as a three-dimensional five-directional structure with a total of 240 yarns, a main yarn array of 6 rows and 36 columns, a knot height of 5mm, and a total of 18 cycles.

[0063] The blade model was analyzed, and there were three bending points. The pre-bending cross sections were determined to be B-11, B-12, and B-13, and the bending reference planes were B-21, B-22, and B-23. The weaving areas at the bending points were divided into sections B-11-B-21, B-12-B-22, and B-13-B-23. Based on the 5mm flower node height, the asynchronous weaving areas were divided into two cycles, two cycles, and three cycles, respectively, parallel to the pre-bending cross sections B-11, B-12, and B-13. The cycle lines and the ending boundaries B-21, B-22, and B-23 formed one intersection point, two intersection points, and two intersection points, respectively.

[0064] Weaving begins with the leaf root as the starting section. When weaving reaches the bending area B-11-B-21, B-12-B-22, and B-13-B-23, the yarn array is re-arranged in sections. The yarn carrier is controlled to complete the weaving of different sections. At the bending reference planes B-21, B-22, and B-23, a tool is used to lift the stepped weaving opening 3 before bending to the horizontal weaving opening 4 after bending, fix the formed fabric, and continue synchronous weaving.

[0065] After 18 machine cycles accompanied by tightening motion, a complete three-dimensional precast body with a curved shape is finally obtained.

[0066] Example 3

[0067] The three-dimensional weaving method with the preform of variable bending structure is used to process a preform with different variable bending structures, such as Figure 7 As shown in the figure, the preform is another marine propeller blade, the main bearing direction is along the length direction of the blade, the length of the blade is 800mm, the width is 240mm, and the thickness is 20mm.

[0068] According to the performance requirements of the product, the preform is designed as a three-dimensional six-direction structure, the total number of yarns is 240, the main array of yarns is 10 rows and 172 columns, the repeat height is 8mm, and the total number of cycles is 100.

[0069] The blade model has four variable bending positions, the pre-bending cross sections are C-11, C-12, C-13 and C-14, and the variable bending reference surfaces are C-21, C-22, C-23 and C-24; the weaving areas C-11-C-21, C-12-C-22, C-13-C-23 and C-14-C-24 are divided into different zones, and the different step weaving areas are divided into two cycles, four cycles, six cycles and two cycles according to the 8mm repeat height, the cycle lines and the end boundaries C-21, C-22, C-23 and C-14 form one intersection, three intersections, four intersections and two intersections respectively.

[0070] The blade root is used as the starting weaving cross section to start weaving, when the weaving reaches the weaving areas C-11-C-21, C-12-C-22, C-13-C-23 and C-14-C-24, the yarn array is re-arranged, the carrier operation is controlled to complete the weaving of different zones, and at the variable bending reference surfaces C-21, C-22, C-23 and C-24, the variable bending front step-shaped weft knuckles 3 are lifted to the variable bending rear horizontal weft knuckles 4 using a tool, the formed fabric is fixed, and the synchronous weaving is continued.

[0071] After 100 machine cycles and accompanied by the tightening movement, the complete three-dimensional preform with variable bending shape is obtained.

Claims

1. A method of three-dimensional weaving with a variable bend preform, characterized in that, The four-step method three-dimensional multi-directional weaving process is carried out from one end of the main bearing direction of the preform as the starting weaving section, and in the weaving process, the different step weaving is designed in the bending structure, and the tool is used to lift the weft to the horizontal state to realize the bending, and after the above continuous weaving operation, a whole three-dimensional preform with bending shape is formed; The following steps are specifically implemented: Step 1, design the three-dimensional weaving structure of the preform according to the performance requirements of the product; Step 2, determine the weaving direction and weaving parameters: take the main bearing direction of the preform as the main weaving direction, select the end with thick section as the starting weaving section, and design the weaving parameters of the preform; Step 3, determine the bending reference surface and different step weaving area boundary of the preform: take the arc length starting cross section of the bending as the pre-bending cross section, and the midpoint cross section as the bending reference cross section; take the pre-bending cross section as the starting boundary of the different step weaving area, and the bending reference cross section as the end boundary of the different step weaving area; Step 4, bending area division: according to the designed repeat height, the different step weaving area is divided into multiple cycles parallel to the pre-bending cross section, and the intersection point of the cycle line and the end boundary of the different step weaving area is the division point of the bending area; Step 5, yarn arrangement: arrange the yarns on the weaving machine chassis according to the four-step method three-dimensional weaving method; Step 6, four-step method weaving: adopt the 1*1 four-step method three-dimensional weaving process to weave; The specific operation steps are: Step 6.1, the weaving yarn carriers in the adjacent rows move horizontally left or right along the row direction by one position of the weaving yarn carrier together with the shaft yarn carrier of the row; Step 6.2, the weaving yarn carriers in the adjacent columns move vertically up or down along the column direction by one position of the weaving yarn carrier; Step 6.3, the weaving yarn carriers in the adjacent rows move horizontally left or right along the row direction by one position of the weaving yarn carrier together with the shaft yarn carrier of the row in the opposite direction of step 6.1; Step 6.4, the weaving yarn carriers in the adjacent columns move vertically up or down along the column direction by one position of the weaving yarn carrier in the opposite direction of step 6.2; at this time, the carriers all return to the initial position, and one movement cycle is completed; Step 7, bending structure forming: when weaving to the bending area, the yarn array is re-arranged according to the designed division, and the carriers are controlled to complete the weaving of different divisions; Step 8, repeat steps 6 and 7, and accompany the tightening movement, and finally obtain a complete three-dimensional preform with bending shape.

2. The three-dimensional braiding process with a variable bend preform of claim 1 wherein, The three-dimensional weaving structure of the preform in step 1 is any one of three-dimensional four-directional, five-directional, six-directional or seven-directional.

3. The three-dimensional braiding process with a variable bend preform of claim 1 wherein, The weaving parameters in step 2 include total yarn count, yarn arrangement row and column number, repeat height, and cycle number.

4. The three-dimensional braiding process with a variable bend preform of claim 1 wherein, The yarn arranging method in step 5 is that one end of the yarn is fixed on a yarn hanging device above the three-dimensional braiding machine, and the other end is hung on a yarn carrier of the three-dimensional braiding machine base through a tension line; the yarn includes braiding yarn and shaft yarn, and is arranged in an array on the base of the braiding machine, wherein the main body array yarn is arranged on the corresponding yarn carrier of the three-dimensional braiding machine base according to the array, and the braiding yarn arranged around the main body yarn array is used as a selvedge; the number of yarns in each row and each column is kept the same.

5. The three-dimensional braiding process with a variable bend preform of claim 1 wherein, The step 7 is specifically operated as follows: the yarn moving operation is performed once every half cycle at the same height to realize the connection of different partitions, and the yarn moving operation cannot change the four-step movement rule; the number of cycles of each partition is different, so that the stepwise fabric along the perpendicular direction of the weaving direction is finally formed, the forming of the weaving area of the variable bending part is realized, at the variable bending reference surface, the fabric is lifted to be horizontal by using a tool, the formed fabric is fixed, and the synchronous weaving is continued.

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