Plastic inner container of carbon fiber reinforced composite material hydrogen storage bottle formed through rotational molding and preparation method of plastic inner container

Abstract

The invention relates to a plastic inner container of a carbon fiber reinforced composite material hydrogen storage bottle formed through rotational molding and a preparation method of the plastic inner container. The inner container comprises a plastic inner container body and a metal insert located at the end of the plastic inner container body. The plastic inner container body and the metal insert are integrally formed at a time through a rotational molding process. Compared with a traditional injection molding method, rotational molding is adopted, so that integral one-time molding of the plastic inner container barrel section can be achieved, and the defects of air leakage and insufficient strength at the welding position are overcome; according to rotational molding, overall one-time forming of the plastic inner container barrel section is achieved, meanwhile, non-glue synchronous connection of the metal insert in the inner container forming process can be achieved, the problems of insufficient air tightness and debonding easily occurring in secondary glue connection are solved, a mechanical interlocking structure is formed by the inner container and the metal insert, and connection is stable and firm.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced composite material manufacturing, and in particular to the manufacturing of pressure vessels in the aircraft, spacecraft and automobile industries, and specifically to a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding and a preparation method thereof. Background Art

[0002] Hydrogen energy is considered the ultimate energy source for automobiles due to its zero-emission characteristics. With the rapid development and industrialization of hydrogen fuel cells and electric vehicles, hydrogen fuel cell vehicles (FCVs) have become the development trend of future automobiles due to their zero-emission characteristics. Hydrogen storage cylinders used to store high-pressure hydrogen are one of the essential key components of fuel cell vehicles.

[0003] The types of automotive hydrogen storage bottles at home and abroad are mainly aluminum liner fiber winding (Type III) and plastic liner fiber winding (Type IV), and are developing in the direction of lightweight, high pressure and large capacity. Among them, Type IV bottles have the advantages of lightweight, high pressure, high hydrogen storage density and long life compared with Type III bottles, and are the key development direction in the future.

[0004] The liner plays a sealing role in the Type IV gas cylinder and is a vital airtight structure. In current technology, most of these parts are formed by injection molding, and the liner material is generally PA or PE.

[0005] The disadvantages of using injection molding technology to form type IV gas cylinder liners in the prior art are mainly the following two aspects:

[0006] 1. Molding process: Injection molding is a low-cost and widely used liner molding method. Since the injection molding process cannot form hollow parts, the injection molding process must be combined with subsequent welding processes to form the liner. However, the airtightness and strength of the liner welding point are difficult to guarantee, resulting in a low welding yield rate.

[0007] 2. Sealing structure: Type IV gas cylinders need to consider the seal between the metal insert at the end of the liner and the plastic liner. The sealing structure must not only be resistant to high and low temperatures and high pressures, but also must not fail in drop tests and fatigue tests. The current metal insert is connected to the liner by gluing after the liner is formed through the injection molding process. Defects such as debonding and air leakage are prone to occur at the glued joints, and the seal between the metal insert and the plastic and the durability of the seal are difficult to guarantee. Summary of the invention

[0008] In view of the above problems, the present invention provides a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding and a preparation method thereof.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding, comprising a plastic liner body and a metal insert located at the end of the plastic liner body; the plastic liner body and the metal insert are integrally molded at one time by a rotational molding process.

[0011] Furthermore, a limiting groove is provided on the metal insert, and the limiting groove includes an axial limiting ring and a circumferential limiting hole, which are respectively used to limit the axial pressure bearing and circumferential rotation of the metal insert.

[0012] Furthermore, during the plastic melt molding process of the rotational molding process, a mechanical interlocking structure is formed at the limiting groove of the metal insert to ensure the air tightness of the connection structure between the liner and the metal insert.

[0013] A method for preparing a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle comprises the following steps:

[0014] Place the metal insert in the corresponding position of the mold cavity of the rotational molding process and fix it, put the resin powder of appropriate quality into the mold, and close the mold;

[0015] Rotate the mold, heat it up until the resin melts and reaches the optimal flow temperature, and then keep it warm until the resin is evenly coated on the mold cavity;

[0016] The mold is cooled and demoulded to obtain a rotationally molded plastic liner body and a metal insert, wherein the metal insert forms a mechanical interlocking structure with the plastic liner body at its limiting groove.

[0017] Furthermore, the limiting groove on the metal insert includes an axial limiting ring and a circumferential limiting hole, which are respectively used to limit the axial pressure bearing and circumferential rotation of the metal insert.

[0018] Furthermore, during the heat preservation and cooling process, the mold is kept in a high-speed rotating state to ensure that the resin melt is evenly distributed on the surface of the mold cavity.

[0019] Furthermore, the cooling is first performed by free cooling and then by air cooling, so as to avoid deformation of the inner tank and incomplete release of internal stress due to too rapid cooling.

[0020] Furthermore, after the temperature of the mold reaches below 60° C. through the cooling, the mold insert is removed and water is sprayed to cool both ends of the mold, and finally the heads at both ends of the mold are removed to complete demoulding.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) Compared with the traditional injection molding method, rotational molding can realize the overall one-time molding of the plastic liner tube section, avoiding defects such as air leakage and insufficient strength at the welding point;

[0023] (2) While rotational molding realizes the overall one-time molding of the plastic liner tube section, it can also realize the glue-free synchronous connection of the metal insert during the liner molding process, avoiding the problems of insufficient airtightness and debonding that are prone to occur in secondary bonding. The liner and the metal insert form a mechanical interlocking structure with a stable and reliable connection, which is impossible to achieve with the injection molding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the inner liner molding process flow.

[0025] Figure 2 It is a structural diagram of the molding die.

[0026] Figure 3 It is a structural diagram of the connection between the metal insert and the plastic liner. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below through specific embodiments and drawings.

[0028] The invention provides a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding, and can achieve the following requirements:

[0029] 1. The rotational molding process is used to realize the integral one-time molding of the plastic liner, so as to achieve the overall air tightness and strength of the liner and improve the manufacturing efficiency of the liner;

[0030] 2. Improve the connection structure between the plastic liner and the end metal insert, directly realize the connection of the metal insert when the liner is formed, and improve the seal between the metal insert and the plastic as well as the reliability and durability of the seal.

[0031] The present invention uses a rotational molding process to form a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle, and the process is as follows: Figure 1 As shown, the specific steps are as follows:

[0032] 1. Place the metal insert of the liner in the corresponding position in the mold cavity and fix it. Calculate the resin mass required for rotational molding according to the liner digital model (mathematical model), put the corresponding mass of resin powder into the mold, and close the mold.

[0033] The structure of the molding die is as follows Figure 2 The liner body is made of thermoplastic plastic, and the end is embedded with a metal insert to connect the valve. The metal insert is directly connected to the liner during the liner molding process, and a limit groove is designed on the insert. The connection structure between the metal insert and the liner is shown in Figure 3As shown. The limit groove is divided into axial limit ring 1, axial limit ring 2 and circumferential limit hole, which are used to limit the axial pressure and circumferential rotation of the metal insert respectively. During the plastic melt molding process, a mechanical interlocking structure is formed at the limit groove of the metal insert, without the need for secondary bonding, thereby ensuring the airtightness of the connection structure between the liner and the metal insert.

[0034] 2. Rotate the mold, heat it up until the resin melts and reaches the optimal flow temperature (the lowest viscosity point on the resin viscosity-temperature curve), then start to keep it warm until the resin is evenly coated on the mold cavity and then take it out of the oven to cool down. During heat preservation and cooling, the mold keeps rotating at a high speed to ensure that the resin melt is evenly distributed on the surface of the mold cavity. When cooling, first cool it down freely and then cool it down with air to avoid deformation of the liner and incomplete release of internal stress due to too fast cooling.

[0035] 3. After the mold temperature reaches below 60°C, remove the mold insert and spray water to cool both ends of the mold. Finally, remove the heads (plugs) at both ends of the mold to complete demoulding.

[0036] The key points of the present invention are:

[0037] 1. The present invention discloses a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding. The main body of the liner is made of thermoplastic plastic, and the end is embedded with a metal insert to connect the valve. The rotational molding process is used to achieve the overall one-time molding of the liner, thereby ensuring the overall mechanical properties and air tightness of the liner.

[0038] 2. The metal insert is directly connected to the liner during the liner molding process. A limit groove is designed on the insert. The limit groove is divided into an axial limit ring and a circumferential limit hole, which are used to limit the axial pressure and circumferential rotation of the metal insert respectively. During the plastic melt molding process, a mechanical interlocking structure is formed at the limit groove of the metal insert, and no secondary bonding is required, thereby ensuring the airtightness of the connection structure between the liner and the metal insert. Figure 3 shown.

[0039] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and implement it accordingly. It can be understood by those skilled in the art that various replacements, changes and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the contents disclosed in the embodiments of this specification, and the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding, characterized in that: It comprises a plastic liner body and a metal insert located at the end of the plastic liner body; the plastic liner body and the metal insert are integrally formed at one time through a rotational molding process.

2. The plastic liner of the carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding according to claim 1, characterized in that: The metal insert is provided with a limiting groove, which includes an axial limiting ring and a circumferential limiting hole, which are respectively used to limit the axial pressure bearing and circumferential rotation of the metal insert.

3. The plastic liner of the carbon fiber reinforced composite material hydrogen storage bottle formed by rotational molding according to claim 2, characterized in that: During the plastic melt molding process of the rotational molding process, a mechanical interlocking structure is formed at the limiting groove of the metal insert to ensure the air tightness of the connection structure between the liner and the metal insert.

4. A method for preparing a plastic liner of a carbon fiber reinforced composite material hydrogen storage bottle, characterized in that: The following steps are involved: Place the metal insert in the corresponding position of the mold cavity of the rotational molding process and fix it, put the resin powder of appropriate quality into the mold, and close the mold; Rotate the mold, heat it up until the resin melts and reaches the optimal flow temperature, and then keep it warm until the resin is evenly coated on the mold cavity; The mold is cooled and demoulded to obtain a rotationally molded plastic liner body and a metal insert, wherein the metal insert forms a mechanical interlocking structure with the plastic liner body at its limiting groove.

5. The method according to claim 4, characterized in that The limiting groove on the metal insert includes an axial limiting ring and a circumferential limiting hole, which are respectively used to limit the axial pressure bearing and circumferential rotation of the metal insert.

6. The method according to claim 4, characterized in that During the heat preservation and cooling process, the mold keeps rotating at a high speed to ensure that the resin melt is evenly distributed on the surface of the mold cavity.

7. The method according to claim 4, characterized in that The cooling is firstly free cooling and then air cooling, so as to avoid deformation of the inner tank and incomplete release of internal stress due to too fast cooling.

8. The method according to claim 4, characterized in that After the mold temperature reaches below 60° C. through the cooling, the mold insert is removed and water is sprayed to cool both ends of the mold. Finally, the heads at both ends of the mold are removed to complete demoulding.

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