Three-dimensional braiding method for large-diameter solid rod-shaped preforms

Abstract

The present invention provides a three-dimensional braiding method for a large-diameter solid rod-shaped preform. The method first utilizes a rectangular braiding machine to three-dimensionally braid a core rod preform having a solid cross-section. The core rod preform is then subjected to at least one three-dimensional circular braiding operation using a circular braiding machine, using the core rod preform as a core mold, to obtain a thickened solid cross-section preform. The present invention utilizes existing rectangular and circular braiding machines and can be used for production without changing the yarn fineness (e.g., a commercially available, readily available, inexpensive, high-quality fiber) or existing technical support requirements (e.g., the yarn storage capacity of the yarn carrier, the specifications of the yarn winding machine, etc.). Furthermore, the method does not require the redesign, manufacture, or purchase of large, expensive three-dimensional braiding machines or the modification of factory buildings.

Description

Technical Field

[0001] The invention relates to a three-dimensional weaving method for a large-diameter solid rod-shaped preform, and also relates to a three-dimensional weaving structure of the large-diameter solid rod-shaped preform. Background Art

[0002] Existing 3D weaving methods and applications are all focused on the use of a specific 3D weaving machine. For example, when producing preforms with solid cross-sections such as solid square, rectangular, polygonal, or even circular, elliptical or airfoil shapes, or cross-sections with square inner holes such as mouth-shaped or sun-shaped, a rectangular weaving machine is used. When producing hollow rotating bodies, or hollow elliptical, airfoil-shaped or polygonal tubular preforms with external chamfers, a 3D circular weaving machine is used. It can be said that although both types of equipment use 3D weaving technology, their application scenarios are completely different and they cannot be used interchangeably.

[0003] For example, if you want to weave a solid preform with a circular cross-section for making cables, rods or spring wires of coil springs, etc., you need to set the weaving platform of the rectangular weaving machine in a combined rectangular manner to have an outer contour close to a circle. The spindle on such a platform will drive the yarn on the spindle during the weaving movement to complete the weaving of the preform with a circular cross-section.

[0004] Generally, the cross-sectional dimensions of a circular cross-section preform are affected by the size of the rectangular weaving platform and the fineness of the weaving yarn carried by the spindle. That is, the larger the platform and the thicker the yarn, the larger the cross-sectional diameter of the woven preform will be, and vice versa, the smaller the cross-sectional diameter of the preform will be.

[0005] However, the above methods of changing the cross-sectional size all have some limitations. Specifically, the size of a general weaving platform is determined by the design, and it is difficult to increase the size of the platform online. The use of thickened yarn will be limited by the size of the yarn carrier. After the weaving platform is manufactured, the capacity of the yarn carrier that can be used is also determined by the upper limit. Therefore, if thicker yarn is used, the length of the yarn stored in the yarn carrier will be shortened accordingly. In this way, the length of the preform that can be woven will be limited, or the yarn carrier filled with yarn will need to be frequently replaced during the weaving process, affecting the weaving efficiency.

[0006] Circular braiding machines are mostly used for weaving tubular cross-section preforms. For a specifically designed circular braiding machine, the number of yarn-carrying spindles has an upper limit. Therefore, the inner hole of the woven tubular preform usually has a minimum size depending on the fineness of the fiber used. The wall thickness also changes with the diameter of the core mold and has an upper limit on the thickness. Therefore, it cannot be used to weave large-diameter solid rod preforms. Summary of the Invention

[0007] The purpose of the present invention is to provide a three-dimensional weaving method for a large-diameter solid rod-shaped preform to solve the above-mentioned technical problems faced in the prior art.

[0008] The technical solution adopted in the present invention is:

[0009] A three-dimensional braiding method for a large-diameter solid rod-shaped preform is characterized in that: a rectangular braiding machine is first used to three-dimensionally braid a core rod preform with a solid cross-section, and then a circular braiding machine is used to perform at least one three-dimensional circular braiding using the core rod preform as a core mold to obtain a thickened preform with a solid cross-section.

[0010] The three-dimensional braiding method of the large-diameter solid rod-shaped preform comprises: compounding the matrix material on the thickened preform, and connecting the core rod preform and the thickened portion on its outer side into one.

[0011] The three-dimensional weaving method of the large-diameter solid rod-shaped preform, wherein: the thickened preform is connected with a joint, and the joint and the thickened preform are composited with a matrix material to form an integrated structure.

[0012] The three-dimensional weaving method of the large-diameter solid rod-shaped preform, wherein: the joint is sleeved on the outside of the thickened preform.

[0013] The three-dimensional weaving method of the large-diameter solid rod-shaped preform is described, wherein: a plurality of needle holes are arranged radially on the joint, and after the thickened preform and the joint form a preliminary connection, a needle body is inserted into the needle hole, and the needle body is connected to the thickened part of the thickened preform and the core rod preform at the same time, and then the matrix material is composited to form an integral connection between the joint, the thickened part of the thickened preform and the core rod preform.

[0014] The three-dimensional weaving method of the large-diameter solid rod-shaped preform, wherein: the matrix material is resin, metal, carbon or ceramic.

[0015] The three-dimensional braiding method of a large-diameter solid rod-shaped preform, wherein: the outer diameter of the core rod preform is greater than or equal to the minimum inner diameter that can be braided by the circular braiding machine.

[0016] In the three-dimensional braiding method of a large-diameter solid rod-shaped preform, the protrusions and depressions on the outer surface of the core rod preform are correspondingly engaged with the depressions and protrusions on the inner surface of the thickened portion to form a nested structure.

[0017] The three-dimensional weaving method of a large-diameter solid rod-shaped preform, wherein: the thickened preform is a straight rod, a curved rod or a spiral rod.

[0018] The three-dimensional weaving method of the large-diameter solid rod-shaped preform, wherein: the thickened preform is coiled into a coil shape.

[0019] The advantages of the present invention are that: the existing rectangular and circular knitting machines can be used, and the corresponding production can be carried out without changing the yarn fineness (such as a commercially available, easily available, cheap, high-quality fiber) or the existing technical support conditions (such as the yarn storage capacity of the yarn carrier, the specifications of the yarn winding machine, etc.), and there is no need to redesign, manufacture or purchase large and expensive three-dimensional knitting machines, renovate factory buildings, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a simplified structural diagram of a core rod preform having a solid circular cross section;

[0021] Figure 2 It is a simplified structural diagram of a solid circular cross-section thickened preform;

[0022] Figure 3 It is a schematic diagram of the connection between the solid circular cross-section thickened preform and the joint.

[0023] Description of the accompanying drawings: core rod preform 1; thickened preform 2; joint 3; external thread 31; needle hole 32; needle body 33. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing a large-diameter solid circular cross-section preform by combining a rectangular braiding machine and a circular braiding machine. First, the rectangular braiding machine is used to three-dimensionally braid a core rod preform with a solid circular cross-section through design and platform setting, using yarn of appropriate fineness. Then, the circular braiding machine is used to perform three-dimensional circular braiding using the core rod preform as a core mold. The diameter of the solid circular cross-section preform is increased by the thickness achieved by the three-dimensional circular braiding, so as to obtain the required large-diameter solid circular cross-section thickened preform.

[0025] Of course, if the core rod preform is a rectangle or other convex polygon, a thickened rectangle or other convex polygon with rounded corners can be formed by circular braiding.

[0026] The advantages of the present invention are that: the existing rectangular and circular knitting machines can be used, and the corresponding production can be carried out without changing the yarn fineness (such as a commercially available, easily available, cheap, high-quality fiber) or the existing technical support conditions (such as the yarn storage capacity of the yarn carrier, the specifications of the yarn winding machine, etc.), and there is no need to redesign, manufacture or purchase large and expensive three-dimensional knitting machines, renovate factory buildings, etc.

[0027] For example, if Figure 1 As shown, a core rod preform 1 with a solid circular cross section is three-dimensionally woven by a rectangular braiding machine; Figure 2As shown, a solid circular cross-section thickened preform 2 is obtained by using a circular braiding machine to perform three-dimensional circular braiding using the core rod preform 1 as a core mold.

[0028] Afterwards, a matrix material is composited onto the thickened preform 2, connecting the core rod preform and its outer thickened portion to form a single body, thereby increasing structural rigidity and strength. The matrix material can be resin, metal, carbon, ceramic, or other materials. For example, composite resin matrix materials are preferably fabricated using RTM (Resin Transfer Molding), but can also be fabricated using methods such as impregnation, casting, and pultrusion. These are all established processes, so the detailed process is not detailed here.

[0029] In addition, if the thickened preform 2 needs to be connected with one or more joints 3, the joints 3 can be processed together with the thickened preform 2 to form the aforementioned composite matrix material step, thereby forming an integrated structure. Figure 3 As shown, one end of the joint 3 is provided with an external thread 31 (or internal thread) or a lug for connecting with the component to be connected, and the other end of the joint 3 is sleeved with the thickened preform 2 and has a plurality of pinholes 32 arranged radially. After the thickened preform 2 and the joint 3 are sleeved, a needle body 33 is inserted into the pinhole 32, so that the joint 3 can be connected to the thickened part of the thickened preform 2 and the core rod preform 1 at the same time, and then the step of composite matrix material is performed, so as to form an integrated connection structure of the joint 3, the thickened part of the thickened preform 2 and the core rod preform 1, which can improve the connection efficiency and enhance the bearing capacity.

[0030] It should be noted that:

[0031] 1. The rectangular braiding machine needs to be designed so that the outer diameter of the braided core rod preform 1 is greater than or equal to the minimum inner diameter that can be braided by the circular braiding machine. Otherwise, there will be a clear seam between the core rod preform 1 and the thickened portion, and an obvious resin-rich area will be produced in the subsequent composite matrix material step (for resin-based composite materials), or the corresponding matrix phase in other processes, which will be detrimental to the performance of the composite material.

[0032] 2. The core rod preform 1 and the thickened part each have their own fiber structure, and there is no fiber connection between them, so the interface between the two layers becomes a weak area in the structure, which usually cracks first when subjected to a large external load, and then causes the failure of the entire structure; in order to solve this problem, the present invention utilizes the protrusions on the surface of the three-dimensional woven structure (formed by the fibers passing through the surface and then returning to the inside) and the depressions next to the protrusions (formed by the place where there is no fiber entering or exiting the surface), so that the protrusions and depressions on the outer surface of the core rod preform 1 and the depressions and protrusions on the inner surface of the thickened part correspond to each other and interact to form a nested structure, so as to increase the mechanical and other properties on the interface.

[0033] 3. The performance of three-dimensional woven composites has many obvious advantages over composites prepared by other processes. One of them is that all fibers carry the load together, instead of fibers arranged in different directions mainly bearing the load in that direction like other processes. For example, a typical laminate structure has plies in the directions of 0 degrees, ±45 degrees and 90 degrees, and each layer is along a certain direction. If the laminate is subjected to an external load in the direction of 0 degrees, it is mainly borne by the 0-degree layer and partially borne by the ±45-degree layer, while the layer in the 90-degree direction only plays a lateral constraint role and basically does not bear any load. Other one-dimensional (such as pultrusion) and two-dimensional (such as winding) processes also have similar mechanisms. In the present invention, the thickened preform 2 has a woven structure of two parts, a core rod preform 1 and a thickened part, and the fibers between them are discontinuous, which may cause the fibers in the two areas to bear different forces when bearing external loads. That is to say, when the external load continues to increase, one part may be loaded greater than the other part, causing the side with a larger load to be more prone to damage and failure, resulting in the load being borne by the other side, and the other side is usually unable to bear the larger external load independently, thus forming a chain of damage. Such a design obviously cannot achieve the optimal load-bearing capacity; therefore, the present invention designs the internal and external woven structures for compatibility, that is, by adjusting the corresponding woven process parameters-weaving angle, fiber properties, fiber volume content, etc., so that the fibers in each area can produce deformation and force that are as compatible as possible under the action of external loads, so that the woven structure can achieve better results.

[0034] 4. Since the three-dimensional woven preform has excellent flexibility, the fiber bundles can adapt to deformation by sliding during the bending process, so it can adapt to any product shape; the thickened preform 2 in the present application can be formed into a curved rod, a coil spring, etc. in addition to a straight rod shape; further, if a matrix material with better toughness is used for the subsequent curing step of the thickened preform 2, such as the inclined cables used for bridges, anchor cables for offshore oil platforms, sucker rods for oil production wells, etc., the obtained product can be easily coiled into a smaller diameter coil, which is convenient for production, storage, transportation and construction.

[0035] In addition, the above embodiment is described based on an example of only one thickening three-dimensional weaving. In fact, the core rod preform 1 can also be subjected to two or more thickening three-dimensional weavings to form a solid circular cross-section thickened preform 2 with a larger diameter.

Claims

1. A three-dimensional braiding method for a large-diameter solid rod-shaped preform, characterized by: First, a rectangular braiding machine is used to three-dimensionally braid a core rod preform with a solid cross-section, and then a circular braiding machine is used to perform at least one three-dimensional circular braiding using the core rod preform as a core mold to obtain a thickened preform with a solid cross-section; The protrusions and depressions on the outer surface of the core rod preform are correspondingly engaged with the depressions and protrusions on the inner surface of the thickened portion to form a nested structure; The matrix material is composited on the thickened preform, and the core rod preform and the thickened portion on its outer side are connected as one body.

2. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 1, characterized in that: The thickened preform is connected with a joint, and the joint and the thickened preform are composited with a matrix material to form an integral structure.

3. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 2, characterized in that: The joint is sleeved on the outer side of the thickened preform.

4. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 3, characterized in that: There are multiple pinholes arranged radially on the joint. After the thickened preform and the joint form a preliminary connection, a needle body is inserted into the pinhole, and the needle body is connected to the thickened part of the thickened preform and the core rod preform at the same time. Thereafter, the matrix material is composited to form an integrated connection between the joint, the thickened part of the thickened preform and the core rod preform.

5. The three-dimensional braiding method for a large-diameter solid rod-shaped preform according to any one of claims 2 to 4, characterized in that: The matrix material is resin, metal, carbon or ceramic.

6. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 1, characterized in that: The outer diameter of the core rod preform is greater than or equal to the minimum inner diameter that can be braided by the circular braiding machine.

7. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 1, characterized in that: The thickened preform is a straight rod, a curved rod or a spiral rod.

8. The three-dimensional braiding method of a large-diameter solid rod-shaped preform according to claim 1, characterized in that: The thickened preform is coiled into a coil shape.

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