Method and device for manufacturing composite pipe

Abstract

A manufacturing method of a composite material pipe comprises the following steps: providing a shape memory alloy rod as a core mold, coating a release agent on the core mold, weaving a tubular preform on the surface of the core mold by using composite material fibers, and depositing a filling material on the surface of the tubular preform to obtain the composite material pipe, and the core mold is axially stretched, so that the diameter of the core mold is reduced, and the core mold is pulled out to realize demolding. According to the method, the demolding efficiency can be improved, core mold reuse is achieved, and the production cost is reduced. The invention further provides a composite pipe manufacturing device.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and specifically relates to a composite material pipe manufacturing method and device. Background Art

[0002] Fuel cladding is crucial to the safety of the reactor. Compared with zirconium alloy used to manufacture conventional fuel cladding, silicon carbide has the advantages of low thermal neutron absorption, corrosion resistance, low hydrogen aggregation and good high temperature performance. Therefore, fuel cladding made of silicon carbide composite pipes is considered to have good application prospects. At present, the preparation process of existing silicon carbide composite pipes is as follows: first, a multi-layer silicon carbide material is woven on a rod-shaped core mold, and then silicon carbide is further deposited on the multi-layer silicon carbide braided body through a chemical vapor deposition (CVD) process to improve the sealing and integrity of the cladding; finally, the core mold is pulled out to obtain a silicon carbide composite pipe. In this process, the friction between the composite pipe and the core mold is very large, and the cladding is difficult to demold. The conventional demolding agent has limited effect, which affects the production efficiency and product quality. Some processes use graphite or quartz core molds, which break the core molds during demolding, resulting in increased production costs. Therefore, providing a composite pipe manufacturing method that is easy to demold has positive significance for optimizing the production efficiency of composite cladding. Summary of the invention

[0003] The purpose of the present invention is to provide a composite material pipe manufacturing method to improve the demoulding efficiency of the composite material pipe. The present invention also provides a composite material pipe manufacturing device.

[0004] According to an embodiment of one aspect of the present invention, a method for manufacturing a composite material pipe is provided, the method comprising the following steps: providing a core mold, wherein the core mold is configured as a shape memory alloy rod; coating a release agent on the surface of the core mold, and weaving a tubular preform on the surface of the core mold using composite material fibers; depositing a filling material on the surface of the tubular preform to obtain a composite material pipe; axially stretching the core mold to reduce the diameter of the core mold; and pulling out the core mold to achieve demolding of the composite material pipe.

[0005] This method utilizes the good deformation ability of shape memory alloys and reduces the diameter of the core mold by stretching and deforming the core mold during demolding, thereby reducing the friction between the composite material pipe and the core mold, reducing the difficulty of demolding, and improving the demolding efficiency.

[0006] Furthermore, in some embodiments, the core mold is made of nickel-titanium alloy, nickel-titanium-copper alloy, copper-aluminum-nickel alloy, copper-aluminum-manganese alloy or iron-manganese-silicon alloy.

[0007] Furthermore, in some embodiments, the composite material fiber is silicon carbide fiber.

[0008] Furthermore, in some embodiments, the weaving method of the tubular preform is: the composite fibers are arranged circumferentially around the core mold, the composite fibers are connected to a yarn carrier of a contoured three-dimensional weaving machine, the composite fibers are driven by the yarn carrier to interweave to obtain a weaving knot, and the circumferential yarn is wound around to form a three-dimensional weaving structure.

[0009] Furthermore, in some embodiments, the filling material is made of the same material as the composite material fiber.

[0010] Furthermore, in some embodiments, the release agent includes graphite emulsion or molybdenum disulfide.

[0011] Furthermore, in some embodiments, when the core mold is axially stretched, the core mold is stretched to a stress platform stage of the shape memory alloy.

[0012] Furthermore, in some embodiments, the method further includes the step of heating the mandrel to restore the diameter of the mandrel.

[0013] According to another embodiment of the present invention, there is provided a composite material pipe manufacturing device, which includes a core mold, a contoured three-dimensional braiding machine, a vapor deposition device, and a stretching device. The composite material pipe manufacturing device is used in the composite material pipe manufacturing method provided in any of the above embodiments. The core mold is configured as a shape memory alloy rod, the contoured three-dimensional braiding machine is used to weave the composite material fibers on the surface of the core mold, the vapor deposition device is used to deposit the filling material, and the stretching device is used to stretch the core mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the core mold structure in one embodiment;

[0015] Figure 2 This is a schematic diagram of the composite fuel cladding structure in one embodiment;

[0016] Figure 3 A schematic diagram of composite fiber weaving in one embodiment;

[0017] Figure 4 Schematic diagram of the tensile stress-strain curve of nickel-titanium shape memory alloy.

[0018] Meaning of the reference symbols:

[0019] 1- core mold; 2- yarn carrier; 3- composite material fiber; 4- fuel cladding preform.

[0020] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0022] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0023] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a mechanical structure connection, or a signal connection relationship; it can be a movable connection, or a fixed connection or integration. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0024] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0025] In the description of this article, terms such as "first" and "second" are only used to distinguish different objects and should not be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the technical features described.

[0026] In the description herein, "plurality" means at least two.

[0027] In the field of nuclear power, fuel rod cladding is usually made of zirconium alloy with good neutron permeability and corrosion resistance. However, zirconium alloy will react with water at high temperature to cause corrosion damage, and it is also easy to grow and deform under the influence of long-term neutron irradiation.

[0028] Compared with zirconium alloys, silicon carbide composites have good high-temperature mechanical properties and corrosion resistance. They also have the advantages of low thermal neutron absorption and low production of combustible gases. Therefore, silicon carbide composites have good application prospects in the field of fuel cladding.

[0029] Due to the limitations of the silicon carbide composite material manufacturing process, the existing silicon carbide composite material cladding is usually manufactured using silicon carbide fibers as raw materials. The silicon carbide fibers are woven into a multi-layer structure on a core mold sprayed or coated with a release agent, and silicon carbide is deposited in the silicon carbide fiber structure using chemical vapor deposition to improve the sealing and integrity of the cladding. Finally, the silicon carbide cladding preform is demolded and separated from the core mold, and further processed into a silicon carbide cladding that can be used to load nuclear fuel.

[0030] However, the length of the fuel rod cladding exceeds 4 meters, and the friction of the silicon carbide fabric is relatively large. It is difficult to effectively reduce the friction and achieve effective demolding by simply applying a release agent. Therefore, the current manufacturing process often uses graphite or quartz glass to make core molds, and the core molds are directly broken after the silicon carbide deposition is completed. The disposable core molds cannot be reused, which increases the production cost.

[0031] In order to solve the above problems, an embodiment of the present invention provides a composite material pipe manufacturing method, which uses a reusable mandrel to conveniently realize the demoulding of the composite material fuel cladding.

[0032] The method uses a composite material pipe manufacturing device, which includes a core mold, a contoured three-dimensional braiding machine, a deposition device and a stretching device. Figure 1 As shown, the core mold 1 is a rod-shaped structure; Figure 3 The yarn carrier 2 of the contoured three-dimensional braiding machine can be coaxially arranged with the core mold 1 to weave the composite fiber 3 on the surface of the core mold 1 into a Figure 2 The fuel cladding preform 4 shown; the deposition device is preferably configured as a CVD device, which can deposit the filling material on the surface of the composite fiber 3 and between the fibers in sections or as a whole to improve the sealing and integrity of the composite fabric; the stretching device can axially stretch the core mold 1, so that the core mold 1 is axially elongated and the diameter is reduced. In different embodiments, the device can be set as an integrated integrated device, or a distributed multiple device can be used. For example, the composite fiber 3 can be woven at the first station, transferred to the second station for CVD deposition, and finally the core mold 1 can be stretched and demolded at the third station.

[0033] In the first preferred embodiment, the implementation process of the method is as follows:

[0034] First, a corresponding core mold 1 is provided according to the design specifications of the fuel rod cladding. The core mold 1 adopts a martensitic transformation end temperature (M f) is made of a shape memory alloy with a phase transition temperature higher than room temperature. The shape memory alloy with this phase transition temperature has a martensitic crystal structure at room temperature and has a lower modulus in the martensitic state. The shape memory alloy can undergo detwinning deformation under lower stress, and the shape memory alloy that undergoes detwinning deformation will return to its original shape in the martensitic state after being heated to the martensitic reverse phase transition. Utilizing this characteristic, the shape memory alloy is processed into a shape memory alloy with geometric dimensions that conform to the inner diameter of the fuel rod cladding in the martensitic state. In different embodiments, the shape memory alloy can be a shape memory alloy with a martensitic twinning phase transition, such as a nickel-titanium alloy, a nickel-titanium-copper alloy, a copper-aluminum-nickel alloy, a copper-aluminum-manganese alloy, or an iron-manganese-silicon alloy.

[0035] Next, a release agent is sprayed or applied on the surface of the core mold 1. The release agent can be graphite emulsion or molybdenum disulfide. In a preferred embodiment, graphite emulsion is used to reduce the friction force when the core mold 1 is demolded.

[0036] Use Figure 3 In the manner shown, the composite fiber 3 is woven into a tubular preform on the surface of the core mold 1. In a preferred embodiment, the composite fiber 3 is made of silicon carbide fiber, and other types of composite fibers may also be used in other embodiments. Specifically, the silicon carbide fiber is circumferentially arranged around the core mold 1, and the silicon carbide fiber is connected to the yarn carrier 2 of the contoured three-dimensional braiding machine through a lead wire. The number of rows and layers of the yarn is designed, and the yarn carrier 2 and the core mold 1 rotate circumferentially in opposite directions as shown by arrows a and b. At the same time, the yarn carrier 2 moves regularly to interweave the lead wire and the silicon carbide fiber, and the interwoven yarn is tightened to form a plurality of braided knots; the circumferential yarn is wound in, thereby forming a three-dimensional four-way + circumferentially reinforced or three-dimensional five-way + circumferentially reinforced braided structure; the above process is repeated to obtain a tubular preform.

[0037] Next, the tubular preform is sent to a CVD deposition device for silicon carbide deposition, so that silicon carbide is deposited on the surface of the silicon carbide fiber and between the silicon carbide fibers as a filling material to improve the sealing and integrity of the silicon carbide fiber fabric. After CVD deposition, a silicon carbide fuel cladding preform 4 is obtained.

[0038] Next, a stretching device is used to clamp the two ends of the core mold 1 and stretch it, so that the core mold 1 is elongated along the axial direction and the diameter is reduced, thereby creating a gap between the core mold 1 and the fuel cladding preform 4 and reducing the friction force, so that the core mold 1 can be pulled out and demolded.

[0039] The core mold 1 made of shape memory alloy is prone to detwinning deformation. Taking nickel-titanium shape memory alloy as an example, Figure 4As shown, the stress-strain curve during the stretching process can be divided into five stages: I, II, III, IV, and V. Stage I is the elastic deformation stage of adaptive martensite (memory state SMA); Stage II is the detwinning stress platform, and its deformation process is similar to the Luders band deformation of steel. In this stage, the tensile stress is basically unchanged, but the length and diameter of the material will change significantly due to the detwinning (memory state SMA) deformation. In stage II (detwinning stress platform stage), the core mold 1 is uniformly elongated and the diameter shrinks relatively uniformly along the axial direction, and no significant necking occurs; stage III is the elastic deformation of martensite, stage IV is the uniform plastic deformation of martensite, and stage V is the localized plastic deformation (necking) of martensite. Therefore, in a preferred embodiment, the stretching of the core mold 1 should be within the range of stage II. Within this range, the stress required for stretching is small, and the deformation is uniform, and the stretching should not exceed stage III.

[0040] In a preferred embodiment, the core mold 1 is made of nickel-titanium shape memory alloy, and its martensitic transformation end temperature (M f ) is 35°C, Poisson's ratio ν=0.3, the diameter of the core mold 1 is 10mm, and the total length is 5m. When demolding the fuel cladding preform 4, the diameter of the core mold 1 should be reduced by 0.5mm. It can be calculated that the axial stretching length of the core mold 1 when sufficient radial shrinkage occurs is approximately 0.83m.

[0041] After demoulding, the fuel cladding preform 4 can be further processed into a silicon carbide fuel cladding, filled with fuel pellets and sealed, and sent to the reactor for service.

[0042] In a preferred embodiment, the core mold 1 that has undergone stretching deformation is heated to cause the core mold 1 to undergo a reverse martensitic phase transformation and restore its original geometric dimensions so that it can continue to be used for manufacturing composite fuel cladding, thereby achieving reuse of the core mold 1.

[0043] In the second preferred embodiment, the material used to manufacture the core mold 1 is a material having a martensitic phase transformation starting temperature (M s ) is a shape memory alloy with a phase transition temperature below room temperature. The shape memory alloy with this phase transition temperature exhibits superelasticity during stress loading, that is, after the alloy is stretched to a large strain (the most typical nickel-titanium shape memory alloy has a recoverable strain ≥8%), its shape can be restored during force unloading, while ordinary metal materials, such as steel, usually have an elastic recovery strain of less than 0.5%. Therefore, the superelasticity of the shape memory alloy can be used to achieve demolding. That is, during the demolding process, the core mold 1 is kept loaded, and the superelastic deformation of the shape memory alloy is used to extend the length of the core mold 1 and shrink it radially, thereby achieving the demolding effect; after demolding, the axial load is removed, and the core mold 1 made of the shape memory alloy can naturally recover to its initial size, which is convenient for reuse.

[0044] It should be noted that the first preferred embodiment mentioned above utilizes the shape memory effect of shape memory alloys, while the second preferred embodiment utilizes the superelasticity of shape memory alloys. The difference between the two cases mainly lies in the phase transition temperature of the shape memory alloy. In actual operation, if the martensitic transformation end temperature (M f ) is higher than room temperature. The shape memory effect of the shape memory alloy is mainly used. The shape memory alloy with this phase transition temperature has a martensite crystal structure at room temperature and can undergo detwinning deformation when stretched at room temperature. This detwinning deformation requires the shape memory alloy to be heated to the austenite transformation end temperature (A f ) to fully restore its shape. If the actual operation process uses the martensitic transformation starting temperature (M s ) The core mold is made of shape memory alloy below room temperature, which uses the superelasticity of shape memory alloy. s When the shape memory alloy is stretched at room temperature, it can undergo stress-induced martensitic transformation, thereby showing superelasticity. This superelastic deformation can be restored after stress is unloaded. When applied to the core mold of the present invention, the shape memory effect and superelasticity of the shape memory alloy can achieve the demoulding effect.

[0045] The composite material pipe manufacturing method provided in the above embodiment can effectively reduce the demolding difficulty of the composite material pipe, improve production efficiency, reduce production costs, and realize the reuse of the core mold. The demolding process only requires a simple stretching of the core mold, and the process is simple and reliable. The shape memory alloy used to manufacture the core mold has good high temperature resistance and oxidation resistance, good dimensional stability, and is not prone to mechanical property degradation and dimensional changes during the CVD heating process, which is beneficial to improving the dimensional stability of the composite material cladding preform. This method has positive significance for the application and promotion of new composite fuel claddings such as silicon carbide.

[0046] In other embodiments, the application of the composite pipe manufacturing method and composite pipe manufacturing device provided in the above embodiments is not limited to the manufacture of composite fuel cladding, but can also be used for the manufacture of heat exchange tubes, furnace tubes or conveying pipes for corrosive chemical liquids made of composite fibers such as silicon carbide.

[0047] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure or method steps involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a composite material pipe, characterized in that: The following steps are involved: Providing a core mold, wherein the core mold is configured as a shape memory alloy rod; Coating a release agent on the surface of the core mold, and weaving a tubular preform on the surface of the core mold using composite fiber; Depositing a filling material on the surface of the tubular preform to obtain a composite material tube; axially stretching the core mold to reduce the diameter of the core mold; The core mold is pulled out to realize demoulding of the composite material pipe.

2. The method for manufacturing a composite material pipe according to claim 1, characterized in that: The core mold is made of nickel-titanium alloy, nickel-titanium-copper alloy, copper-aluminum-nickel alloy, copper-aluminum-manganese alloy or iron-manganese-silicon alloy.

3. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: The composite material fiber is silicon carbide fiber.

4. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: The weaving method of the tubular preform is as follows: the composite material fibers are arranged circumferentially around the core mold, the composite material fibers are connected to the yarn carrier of a contoured three-dimensional weaving machine, the composite material fibers are driven by the yarn carrier to interweave to obtain a weaving knot, and the circumferential yarn is wound into a three-dimensional weaving structure.

5. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: The filling material is made of the same material as the composite material fiber.

6. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: The release agent includes graphite emulsion or molybdenum disulfide.

7. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: When the core mold is axially stretched, the core mold is stretched to the stress platform stage of the shape memory alloy.

8. The method for manufacturing a composite material pipe according to claim 1 or 2, characterized in that: The method further includes heating the mandrel to restore the diameter of the mandrel.

9. A composite material pipe manufacturing device, comprising a core mold, a contoured three-dimensional braiding machine and a vapor deposition device, characterized in that: It also includes a stretching device, and the composite material pipe manufacturing device is used in the composite material pipe manufacturing method as described in any one of claims 1 to 8, wherein the core mold is configured as a shape memory alloy rod, the contoured three-dimensional weaving machine is used to weave the composite material fibers on the surface of the core mold, the vapor deposition device is used to deposit the filling material, and the stretching device is used to stretch the core mold.

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