Forming method of low-cost S-shaped composite material pipeline

Abstract

The invention discloses a forming method of a low-cost S-shaped composite material pipeline, which comprises the following steps of: firstly, manufacturing a thermoplastic core mold, paving prepreg by using the thermoplastic core mold as a composite material pipeline paving mold, packaging by using a vacuum bag after paving, and curing at low temperature by using a drying oven; in order to ensure that the composite material pipeline meets various use working condition requirements in a high-temperature environment, high-temperature post-curing treatment needs to be carried out after low-temperature curing is completed, softening of the thermoplastic core mold can be achieved in the high-temperature post-curing process, and demolding of the thermoplastic core mold can also be achieved while the high-temperature post-curing treatment is completed. According to the method, the problems that a core mold of a large-curvature composite material pipeline product cannot be demolded and the core mold is left can be solved, and smooth development of the composite material pipeline with the curvature is achieved; and meanwhile, the thermoplastic core mold can be repeatedly subjected to injection molding and can be repeatedly used, so that the manufacturing cost of using an inflatable air bag and a combined metal core mold is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of S-shaped composite material pipe molding technology, and in particular to a low-cost S-shaped composite material pipe molding method. Background Technology

[0002] Depending on the pipe material and structural form, the pipe manufacturing process also varies. For continuous fiber-reinforced resin-based pipes, there are mainly two types: one is a simple straight-cylinder structure, which usually uses a metal mandrel as the pipe manufacturing mold. The parts are manufactured on the metal mandrel, and after curing, the metal mandrel is extracted to obtain the pipe. Although manufacturing pipes using a straight-cylinder metal mandrel is simple, the mandrel cannot be deformed during demolding, making it unsuitable for complex curved pipes.

[0003] For the second type of curved pipe structure, to ensure the required internal pipe profile, some manufacturers choose to use inflatable mandrels or segmented metal mandrels. While these methods can achieve pipe forming, they are costly. A common current approach is to design the pipe structure as a liner-composite material structure in the initial design phase. The liner serves as the mandrel for the composite material manufacturing process, and after manufacturing, the liner remains inside the pipe. While this method can achieve the manufacturing of complex composite pipe structures, the mandrel cannot be removed after manufacturing. For products with high weight reduction and strength requirements, mandrel residue inevitably leads to increased pipe weight or reduced strength.

[0004] Therefore, it is necessary to find a low-cost manufacturing method that can meet the requirements of complex pipe shapes and ensure the quality of pipe products. Summary of the Invention

[0005] To overcome the problems mentioned above, such as mandrel residue in complex pipe manufacturing and the high manufacturing cost of mandrels, this invention proposes a low-cost molding method for S-shaped composite material pipes. This method ensures product quality, eliminates internal residue after demolding, and significantly reduces manufacturing costs.

[0006] To address the aforementioned technical problems, this invention provides a low-cost method for molding S-shaped composite material pipes, comprising the following steps: Step A: Core mold manufacturing. The core mold is made of chopped glass fiber reinforced thermoplastic material. It is formed by injection molding of chopped fiber and thermoplastic material in a mold. After demolding, the excess material on the surface of the thermoplastic core mold is polished smooth. Step B: Pipe laying. Before laying, a layer of single-sided adhesive release film is laid on the surface of the thermoplastic mandrel; then, the low-temperature curing prepreg is cut using an automatic feeder and laid by hand on the thermoplastic mandrel. Step C: Encapsulation and curing. After the low-temperature curing prepreg is laid, it is sealed in a vacuum bag and then the parts are placed in an oven for curing. The curing temperature is 80±5℃ and the holding time is 2~4h. Step D: Post-curing. To ensure that the parts meet the requirements of various operating conditions under high temperature, after the parts have cured, the vacuum bag is removed and the parts are placed in the oven for post-curing. The post-curing temperature is 180±5℃ and the holding time is 1h. Step E: Demolding. During the post-curing process, the thermoplastic core mold softens and flows at high temperature. After the post-curing is completed, the core mold inside the pipe is quickly removed to complete the demolding, resulting in an S-shaped composite material pipe.

[0007] Preferably, in step A, the molded thermoplastic mold does not lose stiffness below 90°C and softens and becomes fluid above 160°C.

[0008] Preferably, in step B, pipe laying, the first layer of material is pre-compacted after laying, with a pre-compactment vacuum of -0.060MPa to -0.099MPa for a time of not less than 5 minutes.

[0009] Preferably, in step C, encapsulation and curing, the curing temperature of the low-temperature curing prepreg is 80±5℃. At this temperature, the stiffness of the thermoplastic mandrel does not decrease, which satisfies the curing and molding of the composite material pipe. The thermoplastic mandrel provides the support required for part molding and ensures the quality of the inner surface of the pipe. The curing temperature is maintained for 2 to 4 hours.

[0010] Preferably, in step D, after curing, to ensure that the parts meet the requirements of various operating conditions under high temperature, the vacuum bag is removed after the parts are cured, and the parts are placed in the oven for further curing. The post-curing temperature of the product is 180±5℃, and the post-curing holding time is 1h. During the post-curing process, the thermoplastic core mold will soften and have a certain fluidity, and the single-sided adhesive release film will also shrink and deform to a certain extent, so as to realize the subsequent demolding of the thermoplastic core mold.

[0011] Preferably, in step E, during the post-curing process, the thermoplastic core mold softens and flows at high temperature. After the post-curing is completed, the thermoplastic core mold is demolded as soon as possible. The demolding temperature of the thermoplastic core mold is controlled above 120°C, and demolding is performed using a single-sided adhesive release film at the end.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. The thermoplastic core mold used in this invention is used as a laying mold. Its rigidity does not decrease below 90°C. It can meet the rigidity requirements for laying parts at room temperature. During the low-temperature curing process, it can provide sufficient support to ensure the accuracy of the inner surface of the parts. During the high-temperature post-curing process, the thermoplastic core mold will soften and flow and will not stick to the parts, making it easy to demold. 2. The low-cost S-shaped composite material pipe molding method adopted in this invention can solve the problems of core mold failure and core mold residue in composite material pipe products with large curvature, and realize the successful development of composite material pipes with curvature; at the same time, the thermoplastic core mold can be repeatedly injection molded, realizing reusability, which greatly reduces the manufacturing cost of using inflatable airbags and combined metal core molds. Attached Figure Description

[0013] Figure 1 This is a process flow chart provided by the present invention; Figure 2 This is a schematic diagram of the curing and molding of the S-shaped composite material pipe provided by the present invention.

[0014] In the diagram: 1. Thermoplastic mandrel; 2. S-shaped composite material pipe. Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0016] In addition, the features, operations, and characteristics described in the specification can be combined in any suitable manner to form various embodiments. Similarly, the steps or actions described in the method can be rearranged in a manner that is readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the purpose of clearly describing a particular embodiment and are not necessarily required orders, unless otherwise stated that a particular order must be followed. Example

[0017] This invention provides a low-cost molding method for S-shaped composite material pipes. Please refer to [link / reference]. Figure 1 and Figure 2 It includes the following steps: Step A: Core mold manufacturing. The core mold is made of chopped glass fiber reinforced thermoplastic material. It is formed by injection molding of chopped fiber and thermoplastic material in a mold. After demolding, the excess material on the surface of thermoplastic core mold 1 is polished smooth. Step B: Pipe laying. Before laying, a layer of single-sided adhesive release film is laid on the surface of thermoplastic mandrel 1; then, the low-temperature curing prepreg is cut using an automatic feeder and laid by hand on thermoplastic mandrel 1. Step C: Encapsulation and curing. After the low-temperature curing prepreg is laid, it is sealed in a vacuum bag and then the parts are placed in an oven for curing. The curing temperature is 80±5℃ and the holding time is 2~4h. Step D: Post-curing. To ensure that the parts meet the requirements of various operating conditions under high temperature, after the parts have cured, the vacuum bag is removed and the parts are placed in the oven for post-curing. The post-curing temperature is 180±5℃ and the holding time is 1h. Step E: Demolding. During the post-curing process, the thermoplastic core mold 1 softens and flows at high temperature. After the post-curing is completed, the core mold inside the pipe is quickly removed to complete the demolding, resulting in the S-shaped composite material pipe 2.

[0018] Specifically, in step A, the core mold manufacturing process, the formed thermoplastic core mold 1 has no stiffness reduction below 90°C, and softens and has a certain fluidity above 160°C.

[0019] Specifically, in step B, pipe laying, after the first layer of material is laid, a pre-compaction is performed. The pre-compaction vacuum degree is -0.060MPa to -0.099MPa, and the time is not less than 5 minutes.

[0020] Specifically, in step C, encapsulation and curing, the curing temperature of the low-temperature curing prepreg is 80±5℃. At this temperature, the stiffness of the thermoplastic mandrel 1 does not decrease, which satisfies the curing and molding of the composite material pipe. The thermoplastic mandrel 1 provides the support required for part molding and ensures the quality of the inner surface of the pipe. The curing temperature is maintained for 2 to 4 hours.

[0021] Specifically, in step D, post-curing, to ensure that the parts meet the requirements of various operating conditions under high temperature, the vacuum bag is removed after the parts are cured, and the parts are put into the oven for post-curing treatment. The post-curing temperature of the product is 180±5℃, and the post-curing holding time is 1h. During the post-curing process, the thermoplastic core mold 1 will soften and have a certain fluidity, and the single-sided adhesive release film will also shrink and deform to a certain extent, so as to realize the subsequent demolding of the thermoplastic core mold 1.

[0022] Specifically, in step E, during the post-curing process, the thermoplastic core mold 1 softens and flows at high temperature. After the post-curing is completed, the thermoplastic core mold 1 is demolded as soon as possible. The demolding temperature of the thermoplastic core mold 1 is controlled above 120°C, and demolding is performed through a single-sided adhesive release film at the end.

[0023] The low-cost S-shaped composite material pipe molding method adopted in this invention can solve the problems of core mold failure and core mold residue in composite material pipe products with large curvature, and realize the successful development of composite material pipes with curvature; at the same time, the thermoplastic core mold can be repeatedly injection molded, realizing reusability, which greatly reduces the manufacturing cost of using inflatable airbags and combined metal core molds.

[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalent elements of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0025] Furthermore, the above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A low-cost molding method for S-shaped composite material pipes, characterized in that, Includes the following steps: Step A: Core mold manufacturing. The core mold is made of chopped glass fiber reinforced thermoplastic material, which is injection molded from chopped fiber and thermoplastic material in a mold. After demolding, the excess material on the surface of the thermoplastic core mold (1) is polished smooth. Step B: Pipe laying. Before laying, a layer of single-sided adhesive release film is laid on the surface of the thermoplastic core mold (1); then, the low-temperature curing prepreg is cut using an automatic feeder and laid by hand on the thermoplastic core mold (1); Step C: Encapsulation and curing. After the low-temperature curing prepreg is laid, it is sealed in a vacuum bag and then the parts are placed in an oven for curing. The curing temperature is 80±5℃ and the holding time is 2~4h. Step D: Post-curing. To ensure that the parts meet the requirements of various operating conditions under high temperature, after the parts have cured, the vacuum bag is removed and the parts are placed in the oven for post-curing. The post-curing temperature is 180±5℃ and the holding time is 1h. Step E: Demolding. During the post-curing process, the thermoplastic core mold (1) softens and flows at high temperature. After the post-curing is completed, the core mold inside the pipe is quickly removed to complete the demolding and obtain the S-shaped composite material pipe (2).

2. The molding method for a low-cost S-shaped composite material pipe as described in claim 1, characterized in that, In step A, the core mold manufacturing process, the formed thermoplastic core mold (1) has no stiffness reduction below 90°C and softens and has a certain fluidity above 160°C.

3. The molding method for a low-cost S-shaped composite material pipe as described in claim 1, characterized in that, In step B, pipe laying, the first layer of material is pre-compacted after laying. The pre-compactment vacuum degree is -0.060MPa to -0.099MPa, and the time is not less than 5 minutes.

4. The molding method for a low-cost S-shaped composite material pipe as described in claim 1, characterized in that, In step C, the curing temperature of the low-temperature curing prepreg is 80±5℃. At this temperature, the stiffness of the thermoplastic core mold (1) does not decrease, which satisfies the curing and molding of the composite material pipe. The thermoplastic core mold (1) provides the support required for the molding of the parts and ensures the quality of the inner surface of the pipe. The curing temperature is maintained for 2 to 4 hours.

5. The molding method for a low-cost S-shaped composite material pipe as described in claim 1, characterized in that, In step D, after curing, in order to ensure that the parts meet the requirements of various working conditions under high temperature, the vacuum bag is removed after the parts are cured and the parts are put into the oven for post-curing treatment. The post-curing temperature of the product is 180±5℃ and the post-curing heat preservation time is 1h. During the post-curing process, the thermoplastic core mold (1) will soften and have a certain fluidity. At the same time, the single-sided adhesive release film will also shrink and deform to a certain extent, so as to realize the demolding of the subsequent thermoplastic core mold (1).

6. The molding method for a low-cost S-shaped composite material pipe as described in claim 1, characterized in that, In step E, during the post-curing process, the thermoplastic core mold (1) softens and flows at high temperature. After the post-curing is completed, the thermoplastic core mold (1) is demolded as soon as possible. The demolding temperature of the thermoplastic core mold (1) is controlled above 120°C, and demolding is carried out through a single-sided adhesive release film at the end.

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