Integrated weaving method for intersecting multiple 2.5D layered fabrics in a three-dimensional fabric

Abstract

This invention discloses an integrated weaving method for a three-dimensional fabric composed of multiple 2.5D interwoven fabrics with interlocking spaces. The three-dimensional fabric includes several circular weaving units, each of which includes interlocking and non-interlocking areas. The integrated weaving method includes the following steps: threading heddles, weaving the interlocking areas, and weaving the non-interlocking areas. When lifting the heddles in the non-interlocking areas, the heddle frame corresponding to one of the 2.5D interwoven fabrics is raised relative to the heddle frame corresponding to another 2.5D interwoven fabric to a height at least twice the distance between adjacent heddle holes. Then, the different 2.5D interwoven fabrics are individually weft-in and weft-out performed, with the different 2.5D interwoven fabrics in a separated state. Finally, the weaving unit is repeated until the weaving is completed. Compared with traditional technology, this method can achieve the separation and interlocking of two or more fabrics, ensuring the integrity of the three-dimensional fabric, realizing the integrated weaving of interlocking fabrics, and ensuring good mechanical properties at the connection points of different planes.

Description

Technical Field

[0001] This invention belongs to the field of three-dimensional fabric weaving technology, and in particular relates to an integrated weaving method for a three-dimensional fabric in which multiple 2.5D interlaced fabrics are interspersed at intervals. Background Technology

[0002] High-performance prefabricated 2.5D layered structures are common three-dimensional components used in the aerospace field. These components require high strength, high temperature resistance, and non-delamination properties.

[0003] Currently, 2.5D layered structures can be used to weave flat fabrics. In this structure, warp and weft yarns of different layers interweave and interlock in the thickness direction to form a stable, non-layered integral structure. Some aerospace components require two or more 2.5D structured fabrics to be interlocked at intervals to form a three-dimensional fabric. Current forming technology involves weaving the required number of 2.5D flat (flat) fabrics separately, and then sewing two or more flat fabrics together to form a three-dimensional fabric with interlocking interwoven layers.

[0004] Existing 2.5D structure weaving technology can only weave a single 2.5D structure flat fabric, and cannot achieve the integral molding of two or more 2.5D fabrics intersecting to form a three-dimensional fabric. Current technology achieves this through bending and sewing different 2.5D flat fabrics. This sewing technique has the following drawbacks: 1. The sewn area has limited strength in reinforcing the fracture toughness between layers, resulting in insufficient strength and limited tensile strength at the junction of the two planes after the preform is composited; 2. Manual positioning at the intersecting points is inefficient, inaccurate, and inconsistent.

[0005] In view of this, the inventor of this case conducted in-depth research, which led to the creation of this case. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated molding and weaving method for a three-dimensional fabric composed of multiple 2.5D interwoven fabrics with spaced intersections, which solves the problems of inaccurate positioning of intersecting three-dimensional fabrics composed of multiple (two or more) 2.5D fabrics, low sewing efficiency at the intersections, and poor tensile strength at the intersections when sewing is used.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A method for integrally forming a three-dimensional fabric of multiple 2.5D interlaced fabrics, wherein the three-dimensional fabric includes at least two 2.5D interlaced fabrics, the different 2.5D interlaced fabrics are connected to each other, and the three-dimensional fabric includes several circular knitting units, each of the circular knitting units including interlacing areas and non-interlacing areas.

[0009] The one-piece molding and weaving method includes the following steps:

[0010] Heddle threading: Based on the length and thickness requirements of the three-dimensional fabric, prepare the required length, number of rows, and number of layers of warp yarns. Thread the warp yarns of the three-dimensional fabric into the heddle holes of the corresponding heddle frames. Each heddle frame has several heddle wires, and each heddle wire has several heddle holes at different heights. The warp yarns of different 2.5D layered fabrics are threaded onto different heddle frames. The warp yarns of the three-dimensional fabric located in different rows are threaded onto different heddle wires. The warp yarns of the 2.5D layered fabric located in different layers are threaded onto heddle holes at different heights.

[0011] Interlocking Zone: According to the established movement law of the heald frame in the 2.5D weaving structure, the movement of the heald eye drives the movement of the warp yarns to form an opening. When lifting the heald, the heald frame corresponding to one of the 2.5D layered fabrics is raised to a position higher than the heald frame corresponding to the other 2.5D layered fabric. The heald frames corresponding to the two different 2.5D layered fabrics are controlled to move to a position where the heald eyes of the different heald frames are evenly arranged vertically. Then, weft insertion and beat-up operations are performed. The weft yarns are evenly distributed between the two different 2.5D layered fabrics, and the weft yarns form junctions with the warp yarns between the two different 2.5D layered fabrics, weaving the two different 2.5D layered fabrics into a whole. The operation is repeated according to the movement law of the heald frame until the length of the interlocking zone reaches the design requirements.

[0012] Weaving the non-interlocking zone: According to the established movement law of the heald frame in the 2.5D weaving structure, the movement of the heald eye drives the movement of the warp yarns to form an opening. When lifting the heald, the heald frame corresponding to one of the 2.5D layered fabrics is lifted to a position higher than the heald frame corresponding to another 2.5D layered fabric. The heald frame corresponding to one of the 2.5D layered fabrics is then raised relative to the heald frame corresponding to another 2.5D layered fabric to a height at least twice the distance between adjacent heald eyes. Then, the different 2.5D layered fabrics are subjected to weft insertion and beat-up operations respectively. The different 2.5D layered fabrics are in a separated state. The operation is repeated according to the heald frame movement law until the length of the non-interlocking zone reaches the design requirements.

[0013] Repeated weaving unit: Repeat the operation of weaving the intersecting area and the non-intersecting area, and continue to weave the parts of the 2.5D layered continuous fabric in the intersecting and separating states until the three-dimensional fabric reaches the length required by the design.

[0014] Furthermore, the three-dimensional fabric includes a first fabric and a second fabric, wherein the length of the non-interlocking region of the first fabric is greater than the length of the non-interlocking region of the second fabric;

[0015] The integrated molding weaving method also includes relative adjustment of the weaving opening: after the non-interlocking areas of the first fabric and the second fabric are both woven, the weaving opening of the first fabric is located on one side of the weaving opening of the second fabric. The non-interlocking area of ​​the first fabric is folded and clamped using a special external clamp, so that the weaving opening of the first fabric and the weaving opening of the second fabric are flush in the direction of heald lifting.

[0016] When repeating the knitting unit, repeat the knitting of the interlaced area, the knitting of the non-interlaced area, and the relative adjustment of the knitting opening in sequence.

[0017] Furthermore, the tail ends of the warp yarns of the second fabric are respectively inserted into the first heald frame and the second heald frame, and are respectively fixed to the rear yarn hanging frame; the tail ends of the warp yarns of the first fabric are respectively inserted into the third heald frame and the fourth heald frame, and are respectively fixed to the rear yarn hanging frame; the front ends of the warp yarns of the first fabric are fixed to the front yarn hanging device, and the front ends of the warp yarns of the second fabric are fixed to the front yarn hanging device.

[0018] Furthermore, the non-interlacing area of ​​the first fabric is folded and clamped into a Z-shape using a special external clamp. The lengths of the non-interlacing areas of the first fabric and the second fabric are calculated. When the non-interlacing area of ​​the second fabric in the same cycle knitting unit is completed, the second fabric stops weft insertion knitting and continues to knit the non-interlacing area of ​​the first fabric separately according to the calculated length until the length of the non-interlacing area of ​​the first fabric reaches the design requirements.

[0019] Furthermore, when weaving the interlocking area, the 2.5D weaving structure is a 2.5D shallow interlocking direct connection structure and / or a 2.5D shallow interlocking bend connection structure; when weaving the non-interlocking area, the 2.5D weaving structure is a 2.5D shallow interlocking direct connection structure and / or a 2.5D shallow interlocking bend connection structure.

[0020] After adopting the above technical solution, the integrated molding and weaving method of multiple 2.5D interlaced three-dimensional fabrics of the present invention has the following beneficial effects: it can weave interlaced 2.5D three-dimensional fabrics, and by using the design of warp and weft yarn interlacing, it can realize the joining of two or more fabrics into a whole three-dimensional fabric. It can realize the separation and interlacing of two or more fabrics, ensure the integrity of the three-dimensional fabric, realize the interlacing of fabrics into a whole, and ensure good mechanical properties at the connection of different planes.

[0021] To address the issue of inaccurate positioning in traditional sewing, the specific weft yarn positions of intersections and gaps can be calculated based on the weft density of the fabric. This achieves accurate positioning of intersecting yarns, eliminating the need to assemble the fabric into a three-dimensional structure through sewing, thus greatly improving production efficiency. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of the three-dimensional fabric of the present invention;

[0023] Figure 2 This is a schematic diagram of the warp and weft yarn interlacing in the junction area of ​​the present invention;

[0024] Figure 3 This is a schematic diagram of the warp and weft yarn interlacing in the non-interlacing zone of the present invention.

[0025] First fabric 1; Second fabric 2; Knotting area a; Knotting area a1; Knotting area a2; Non-knotting area b; Non-knotting area b1; Non-knotting area b2. Detailed Implementation

[0026] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0027] This invention relates to an integral weaving method for multiple 2.5D interlaced three-dimensional fabrics with spaced intersections. In this invention, "multiple" refers to two or more. For example... Figure 1 As shown, the three-dimensional fabric of the present invention comprises at least two 2.5D interwoven fabrics, which are connected alternately. The three-dimensional fabric includes several circular knitting units, each of which includes an interlacing area a and a non-interlacing area b. The following description uses an example of a three-dimensional fabric comprising two 2.5D interwoven fabrics. Figure 1 As shown, the three-dimensional fabric of the present invention includes a first fabric 1 and a second fabric 2. The interlacing area of ​​the first fabric 1 is a1, the non-interlacing area of ​​the first fabric 1 is b1, the interlacing area of ​​the second fabric 2 is a2, and the non-interlacing area of ​​the second fabric 2 is b2.

[0028] Figure 2 and Figure 3 In the diagram, circles represent warp yarns threaded onto heddle loops, and straight lines represent weft yarns; the four circles above each row of warp yarns represent the warp yarns (layers) of the first fabric; and the four circles below each row of warp yarns represent the warp yarns (layers) of the second fabric.

[0029] Figure 2 There are four rows of warp yarns in total, numbered 1, 2, 3, and 4 from left to right. Each row of warp yarns consists of four warp yarns in the upper half and four warp yarns in the lower half. The upper half (the top four yarns) of each row corresponds to the first fabric, and the lower half (the bottom four yarns) of each row corresponds to the second fabric.

[0030] In this embodiment, the warp yarns of the first and third columns of the first fabric are threaded onto the adjacent heddles of the third heddle frame, and each heddle has four heddle holes, with one warp yarn threaded onto one heddle hole; the warp yarns of the second and fourth columns of the first fabric are threaded onto the adjacent heddles of the fourth heddle frame, and each heddle has four heddle holes, with one warp yarn threaded onto one heddle hole.

[0031] The warp yarns of the first and third columns of the second fabric are threaded on the adjacent heddles of the first heddle frame. Each heddle has four heddle holes, and one warp yarn is threaded through one heddle hole. The warp yarns of the second and fourth columns of the second fabric are threaded on the adjacent heddles of the second heddle frame. Each heddle has four heddle holes, and one warp yarn is threaded through one heddle hole.

[0032] The integral molding and weaving method of the present invention includes the following steps:

[0033] Step S1: Threading the heddles. Based on the length and thickness requirements of the three-dimensional fabric, prepare the required length, number of rows, and number of layers of warp yarns. In this embodiment, the first fabric 1 and the second fabric 2 are both four-layer fabrics, each forming four layers of warp yarns. Thread the warp yarns of the three-dimensional fabric into the heddle holes of the corresponding heddle frames. Each heddle frame has several heddle threads, and each heddle thread has several heddle holes at different heights. In this embodiment, each heddle thread has at least four heddle holes at different heights (specifically, four). The warp yarns of different 2.5D layered fabrics are threaded onto different heddle frames, i.e., the warp yarns of the first fabric 1 and the second fabric 2 are threaded onto different heddle frames. The warp yarns in different rows of the three-dimensional fabric are threaded onto different heddle threads, and the warp yarns in different layers of the 2.5D layered fabric are threaded onto heddle holes at different heights, i.e., the four layers of warp yarns of the first fabric 1 are threaded onto heddle holes at different heights, and the heddle holes corresponding to warp yarns in the same layer are at the same height.

[0034] Specifically, the tail ends of the warp yarns of the second fabric 2 are inserted into the first heald frame and the second heald frame respectively, and are fixed to the rear yarn hanging frame respectively; the tail ends of the warp yarns of the first fabric 1 are inserted into the third heald frame and the fourth heald frame respectively, and are fixed to the rear yarn hanging frame respectively; the front ends of the warp yarns of the first fabric 1 are fixed to the front yarn hanging device, and the front ends of the warp yarns of the second fabric 2 are fixed to the front yarn hanging device.

[0035] Step S2: Weave the interlacing area a. Based on the heald frame movement law of the 2.5D shallow interlacing straight connection structure or the 2.5D shallow interlacing curved connection structure, control the movement of the heald eye to drive the warp yarn movement to form an opening, such as... Figure 2As shown, during heald raising, the heald frame corresponding to one of the 2.5D layered fabrics is raised to a position higher than the heald frame corresponding to the other 2.5D layered fabric. The heald frames corresponding to the two different 2.5D layered fabrics are controlled to be positioned so that the heald eyes of the different heald frames are evenly arranged vertically. Specifically, the distance between the lowest heald eye on the heald frame corresponding to fabric 1 and the highest heald eye on the heald frame corresponding to fabric 2 is equal to the distance between adjacent heald eyes on each heald yarn. Then, weft insertion and beat-up operations are performed. Weft insertion is performed between the warp yarns of each layer in fabric 1. Weft insertion is also performed between the warp yarns of each layer in fabric 2. Weft insertion is also performed between the warp yarns of fabric 1 and fabric 2. The weft yarns are evenly distributed between two different 2.5D interwoven fabrics (i.e., the first fabric 1 and the second fabric 2), and the weft yarns form junctions with the warp yarns between the two different 2.5D interwoven fabrics, interweaving the two different 2.5D interwoven fabrics (i.e., the first fabric 1 and the second fabric 2) into a whole. The operation is repeated according to the heald frame movement law until the length of the junction area reaches the design requirements.

[0036] Step S3: Weave the non-interlacing zone b. Based on the heald frame movement law of the 2.5D shallow interlacing straight connection structure or the 2.5D shallow interlacing curved connection structure, control the movement of the heald eye to drive the warp yarn movement to form an opening, such as... Figure 3 As shown, during heald raising, the heald frame corresponding to one of the 2.5D layered fabrics is raised to a position higher than the heald frame corresponding to the other 2.5D layered fabric. Furthermore, the heald frame corresponding to one of the 2.5D layered fabrics (i.e., the first fabric 1) is raised relative to the heald frame corresponding to the other 2.5D layered fabric (i.e., the second fabric 2) to a height at least twice the distance between adjacent heald eyes (twice the distance between heald eyes in this embodiment). That is, the lowest heald eye on the heald frame corresponding to the first fabric 1 is at least twice the distance between adjacent heald eyes on the same heald yarn compared to the highest heald eye on the heald frame corresponding to the second fabric 2. Then, the two different 2.5D layered fabrics (i.e., the first fabric 1 and the second fabric 2) undergo weft insertion and beat-up operations independently. Weft insertion is performed between the warp yarns of each layer in the first fabric 1. Weft insertion is performed between the warp yarns of each layer in the second fabric 2. No weft insertion is performed between different 2.5D layered fabrics (i.e., between the first fabric 1 and the second fabric 2). Therefore, there are no warp and weft joints between different 2.5D layered fabrics, and they are in a separate state. The operation is repeated according to the heald frame movement law until the length of the non-intersecting area reaches the design requirements.

[0037] In this embodiment, the length of the non-interlocking area b1 of the first fabric 1 is greater than the length of the non-interlocking area b2 of the second fabric 2.

[0038] As a preferred embodiment, the one-piece molding weaving method of the present invention further includes step S4: relative adjustment of the weaving openings. After the non-interlocking area b1 of the first fabric 1 and the non-interlocking area b2 of the second fabric 2 are both woven (i.e. the length reaches the design requirements), since the length of the non-interlocking area b1 of the first fabric 1 is greater than the length of the non-interlocking area b2 of the second fabric 2, the weaving opening 1 of the first fabric is located on one side of the weaving opening of the second fabric 2. The non-interlocking area b1 of the first fabric 1 is folded and clamped using a special external clamp, so that the weaving openings of the first fabric 1 and the second fabric 2 are flush in the heddle lifting direction.

[0039] Step S5: Repeat the operation of weaving the intersecting area a and the non-intersecting area b, and continue weaving the parts of the two different 2.5D interwoven fabrics (first fabric 1 and second fabric 2) that are intersecting and separate until the three-dimensional fabric reaches the length required by the design.

[0040] Furthermore, when repeating the weaving unit, the operations of weaving the interlacing area a in step S2, weaving the non-interlacing area b in step S3, and adjusting the relative weaving openings in step S4 are repeated in sequence.

[0041] In one preferred embodiment, the non-interlacing area b1 of the first fabric 1 is folded and clamped into a Z-shape using a special external clamp. The length of the non-interlacing area b1 of the first fabric 1 and the length of the non-interlacing area b2 of the second fabric 2 are calculated. When the non-interlacing area b2 of the second fabric 2 in the same cycle knitting unit is completed, the second fabric 2 stops weft insertion knitting and continues to knit the non-interlacing area b1 of the first fabric 1 separately according to the calculated length until the length of the non-interlacing area b1 of the first fabric 1 reaches the design requirement.

[0042] In this invention, both the 2.5D shallow cross-linked direct connection structure and the 2.5D shallow cross-linked bent connection structure are well-known 2.5D braided structures in the industry. For example, there are records of the corresponding structures in the reference, Guo Hongwei, Zhang Liquan, Zhu Mengdie. Structural design and weaving process of woven 2.5D fabric for high-performance composite materials [J]. Glass Fiber, 2017(3):1:5. The motion law of the heald frame of this structure is known and will not be described in detail here, nor is it the focus of protection of this invention.

[0043] It should be noted that the three-dimensional fabric of the present invention may further include two or more 2.5D interwoven fabrics. The weaving between any two adjacent 2.5D interwoven fabrics shall be performed by the above-mentioned weaving method of the interwoven area if the weaving is interlaced, and by the above-mentioned weaving method of the non-interlaced area if the weaving is non-interlaced.

[0044] The present invention provides an integral weaving method for multiple 2.5D interlaced three-dimensional fabrics, which has the following advantages: it can weave interlaced 2.5D three-dimensional fabrics, and by using the design of warp and weft yarn interlacing, it can realize the joining of two or more fabrics into a whole three-dimensional fabric. It can realize the separation and interlacing of two or more fabrics, ensuring the integrity of the three-dimensional fabric, realizing the integral molding of interlaced fabrics, and ensuring good mechanical properties at the connection of different planes.

[0045] To address the issue of inaccurate positioning in traditional sewing, the specific weft yarn positions of intersections and gaps can be calculated based on the weft density of the fabric. This achieves accurate positioning of intersecting yarns, eliminating the need to assemble the fabric into a three-dimensional structure through sewing, thus greatly improving production efficiency.

[0046] The above embodiments and accompanying drawings are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for integrally forming and weaving a three-dimensional fabric of multiple 2.5D interlaced layered fabrics, characterized in that: The three-dimensional fabric includes at least two 2.5D interwoven fabrics, with different 2.5D interwoven fabrics connected alternately. The three-dimensional fabric includes several circular knitting units, and each circular knitting unit includes interlacing areas and non-interlacing areas. The one-piece molding and weaving method includes the following steps: Heddle threading: Based on the length and thickness requirements of the three-dimensional fabric, prepare the required length, number of rows, and number of layers of warp yarns. Thread the warp yarns of the three-dimensional fabric into the heddle holes of the corresponding heddle frames. Each heddle frame has several heddle wires, and each heddle wire has several heddle holes at different heights. The warp yarns of different 2.5D layered fabrics are threaded onto different heddle frames. The warp yarns of the three-dimensional fabric located in different rows are threaded onto different heddle wires. The warp yarns of the 2.5D layered fabric located in different layers are threaded onto heddle holes at different heights. Interlocking Zone: According to the established movement law of the heald frame in the 2.5D weaving structure, the movement of the heald eye drives the movement of the warp yarns to form an opening. When lifting the heald, the heald frame corresponding to one of the 2.5D layered fabrics is raised to a position higher than the heald frame corresponding to the other 2.5D layered fabric. The heald frames corresponding to the two different 2.5D layered fabrics are controlled to move to a position where the heald eyes of the different heald frames are evenly arranged vertically. Then, weft insertion and beat-up operations are performed. The weft yarns are evenly distributed between the two different 2.5D layered fabrics, and the weft yarns form junctions with the warp yarns between the two different 2.5D layered fabrics, weaving the two different 2.5D layered fabrics into a whole. The operation is repeated according to the movement law of the heald frame until the length of the interlocking zone reaches the design requirements. Weaving the non-interlocking zone: According to the set movement law of the heald frame of the 2.5D weaving structure, the movement of the heald eye drives the movement of the warp yarn to form an opening. When lifting the heald, the heald frame corresponding to one of the 2.5D layered fabrics is lifted to a position that is higher than the heald frame corresponding to another 2.5D layered fabric. The heald frame corresponding to one of the 2.5D layered fabrics is also raised relative to the heald frame corresponding to another 2.5D layered fabric to a height that is at least twice the distance between adjacent heald eyes on the same heald yarn. Then, the different 2.5D layered fabrics are subjected to weft insertion and beat-up operations respectively. The different 2.5D layered fabrics are in a separated state. The operation is repeated according to the movement law of the heald frame until the length of the non-interlocking zone reaches the design requirements. Repeated weaving unit: Repeat the operation of weaving the intersecting area and the non-intersecting area, and continue to weave the parts of the 2.5D interlocking fabrics in different states of intersection and separation until the three-dimensional fabric reaches the length required by the design. The three-dimensional fabric includes a first fabric and a second fabric, wherein the length of the non-interlocking region of the first fabric is greater than the length of the non-interlocking region of the second fabric. The integrated molding weaving method also includes relative adjustment of the weaving opening: after the non-interlocking areas of the first fabric and the second fabric are both woven, the weaving opening of the first fabric is located on one side of the weaving opening of the second fabric. The non-interlocking area of ​​the first fabric is folded and clamped using a special external clamp, so that the weaving opening of the first fabric and the weaving opening of the second fabric are flush in the direction of heald lifting. When repeating the knitting unit, repeat the knitting of the interlaced area, the knitting of the non-interlaced area, and the relative adjustment of the knitting opening in sequence.

2. The method for integrally forming and weaving a plurality of 2.5D interlaced three-dimensional fabrics with spaced intersections as described in claim 1, characterized in that: The tail ends of the warp yarns of the second fabric are inserted into the first heald frame and the second heald frame respectively, and are fixed to the rear yarn hanging frame respectively; the tail ends of the warp yarns of the first fabric are inserted into the third heald frame and the fourth heald frame respectively, and are fixed to the rear yarn hanging frame respectively; the front ends of the warp yarns of the first fabric are fixed to the front yarn hanging device, and the front ends of the warp yarns of the second fabric are fixed to the front yarn hanging device.

3. The method for integrally forming and weaving a three-dimensional fabric of multiple 2.5D interlaced layered fabrics as described in claim 1, characterized in that: After the non-interlacing area of ​​the first fabric is folded and clamped using a special external clamp, it forms a "Z" shape. The lengths of the non-interlacing areas of the first fabric and the second fabric are calculated. When the non-interlacing area of ​​the second fabric in the same cycle knitting unit is completed, the second fabric stops weft insertion knitting and continues to knit the non-interlacing area of ​​the first fabric separately according to the calculated length until the length of the non-interlacing area of ​​the first fabric reaches the design requirements.

4. The method for integrally forming and weaving a plurality of 2.5D interlaced three-dimensional fabrics with spaced intersections as described in claim 1, characterized in that: When weaving the interlocking area, the 2.5D weaving structure is a 2.5D shallow interlocking direct connection structure and / or a 2.5D shallow interlocking bend connection structure; when weaving the non-interlocking area, the 2.5D weaving structure is a 2.5D shallow interlocking direct connection structure and / or a 2.5D shallow interlocking bend connection structure.

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