Beam structural part and forming die and integrated forming method thereof

Abstract

The invention provides a beam structural part and a forming die and an integrated forming method thereof, the forming die comprises an auxiliary tool, a first core die and a second core die, and the first die and the second die are detachably installed on the auxiliary tool; the forming method comprises the following steps that the second core mold is installed on an auxiliary tool, multiple layers of prepregs are laid on the surface of the second core mold, the surface of the first core mold is sequentially coated with a rubber layer and demolding cloth, then multiple layers of prepregs are laid, then the first core mold is installed on the auxiliary tool, the auxiliary tool is fed into an autoclave for curing and demolding, and the beam structural part is obtained. According to the method, the parts of the multi-lattice beam structural part can be integrally formed, the manufacturing procedures are reduced, the overall strength of the beam structural part is improved, and therefore the market competitiveness of products is improved.

Description

Technical Field

[0001] The invention relates to the technical field of beam structure manufacturing, and in particular to a beam structure, a forming die and an integrated forming method thereof. Background Art

[0002] Beam structural parts are commonly used load-bearing structural parts among many structural parts. They usually play the role of bearing and transmitting loads. They are key structural parts to ensure the rigidity of various products. As the skeleton of the product, they are generally subject to strict quality requirements. Common beam structural parts include I-beams, C-beams, etc. For product structures with high rigidity requirements, beam structural parts are generally distributed orthogonally in the vertical and horizontal directions to form large-sized C-beams with multi-grid structures to strengthen the structural performance of the beam in the orthogonal direction. The strength requirements of the reinforced beam structure itself are high, and for such complex structures with multiple grids, the molding difficulty is relatively large. Currently, it is generally necessary to mold in steps, and different components need to be molded multiple times, and then these components are glued or assembled to form beam structural parts with multi-grid complex structures. However, this type of molding method not only has cumbersome procedures and low molding efficiency, but also multiple molding will inevitably increase the number of defects, and the interlayer performance between the components is poor, that is, the connection performance of the joint surface after the combination of multiple components is not high, and it is easy to be damaged by weak bonding or peeling. Summary of the invention

[0003] The object of the present invention is to provide a beam structure member, a forming die and an integrated forming method thereof. By adopting the forming die and the integrated forming method, the integrated forming of a large-sized beam structure member with a multi-grid structure can be achieved, the production process can be reduced, and the overall strength of the beam structure member can be improved.

[0004] To achieve the above object, the present invention proposes the following technical solutions:

[0005] A forming mold for forming a beam structure, wherein the beam structure is composed of a plurality of first longitudinal C-shaped beams and a plurality of second transverse C-shaped beams connected orthogonally, and a plurality of core lattice cavities are formed between the first C-shaped beams and the second C-shaped beams, and an opening end of the beam structure is provided with a flange folded toward the inner side of the core lattice cavity;

[0006] The mold includes auxiliary tooling, multiple first core molds, and multiple second core molds. The first core mold is a long strip structure, and the second core mold is a cube structure. The auxiliary tooling includes a base and side baffles. The side baffles are installed and enclosed on the four sides of the upper surface of the base. An installation cavity is formed between the side baffles and the upper surface of the base. The first core mold and the second core mold are both detachably installed in the installation cavity. The first core molds are arranged perpendicular to each other, and the second core molds are symmetrically distributed on both sides of each of the first core molds, wherein the first core mold is used to pave the inner ring beam area of ​​the beam structure, and the second core mold is used to pave the flanged beam area of ​​the beam structure.

[0007] As a preferred technical solution of an embodiment of the present invention, a plurality of first mounting positions and a plurality of second mounting positions are provided in the mounting cavity, each of the first core molds is detachably set at each of the first mounting positions through a first positioning pin, and each of the second core molds is detachably set at each of the second mounting positions through a second positioning pin.

[0008] The embodiment of the present invention further provides an integrated molding method, comprising the following molding steps:

[0009] (1) bonding a rubber material to the surface of each first core mold and performing a hot-pressing vulcanization treatment, then laying a release cloth on the surface of the rubber layer, laying multiple layers of prepreg cut into shape on the surface of the first core mold laid with the release cloth, vacuuming and pre-compacting the first core mold with the prepreg, and performing a hot-pressing and pre-curing treatment on the pre-compacted first core mold to obtain the pre-cured first core mold for standby use;

[0010] Wherein, with the C-shaped opening end of the beam structure as the upper end, the surface of the first core mold includes the lower surface of the first core mold, the left side surface of the first core mold, the right side surface of the first core mold, the front side surface of the first core mold and the rear side surface of the first core mold;

[0011] The hot pressing vulcanization treatment sets the hot pressing temperature to 170°C-185°C and the hot pressing pressure to 0.4MPa-0.7MPa;

[0012] (2) installing each of the second core molds at a corresponding position of the installation cavity of the auxiliary tooling, and then laying multiple layers of prepreg cut into shape on the surface of the second core mold, and vacuuming and pre-compacting the second core molds with the prepreg laid thereon,

[0013] Wherein, with the C-shaped opening end of the beam structure as the upper end, the surface of the second core mold includes the upper surface of the second core mold, the left side surface of the second core mold, the right side surface of the second core mold, the front side surface of the second core mold, and the rear side surface of the second core mold;

[0014] (3) Installing the first core mold after pre-curing in step (1) at the corresponding position of the installation cavity of the auxiliary tooling in step (2), so that the first core mold and the second core mold are combined to form a shaping tooling of the beam structure, packaging the auxiliary tooling with the shaping tooling, and then sending it into an autoclave for hot pressing and curing treatment. After the hot pressing and curing treatment is completed, demolding is performed to obtain the beam structure.

[0015] As a preferred technical solution of an embodiment of the present invention, the hot pressing temperature of the hot pressing pre-curing treatment in the step (1) is 50°C-80°C, the hot pressing time is 30min-60min, and the hot pressing pressure is 0.4MPa-0.7MPa.

[0016] As a preferred technical solution of an embodiment of the present invention, the prepreg is a carbon fiber composite material, and the carbon fiber arrangement angles of the prepreg include 0°, 90°, 45° and -45°.

[0017] As a preferred technical solution of an embodiment of the present invention, the number of layers of the prepreg material paved on the surface of the first core mold is 18-20; the number of layers of the prepreg material paved on the surface of the second core mold is 18-20.

[0018] As a preferred technical solution of an embodiment of the present invention, the surface of the first core mold is vacuumed and pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid;

[0019] The surface of the second core mold is vacuumed and pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid.

[0020] As a preferred technical solution of an embodiment of the present invention, the vacuum degree of the vacuum pre-compaction is not less than -70 KPa, and the pre-compaction time is at least 5 minutes.

[0021] As a preferred technical solution of an embodiment of the present invention, the curing temperature of the hot pressing curing treatment in the step (3) is 120°C-150°C, the curing pressure is 0.4MPa-0.7MPa, and the curing time is at least 120min.

[0022] The present invention also provides a beam structure, which is manufactured by the above-mentioned forming method.

[0023] The beam structure member, its forming die and integrated forming method provided by the present invention can realize the integrated forming of parts of multiple component structures, reduce the production process, improve the overall strength of the parts, and thus enhance the market competitiveness of the product.

[0024] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0025] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a structural schematic diagram of the molding die of the present invention;

[0028] Figure 2 It is a structural schematic diagram of the beam structure of the present invention.

[0029] The reference numerals in the figures indicate the following meanings:

[0030] 1-First C-beam 2-Second C-beam 3-First core mold 4-Second core mold 5-Side baffle 6-Base DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0032] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and similar words do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" include the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] In order to realize the integrated molding of multiple component structural parts, reduce the manufacturing process, and improve the overall strength of the parts, an embodiment of the present invention provides a molding die, an integrated molding method using the molding die, and a beam structure manufactured by the integrated molding method.

[0034] Among them, Figure 2 As shown, the beam structure provided by the embodiment of the present invention is composed of a plurality of first longitudinal C-beams 1 and a plurality of transverse second C-beams 2 which are orthogonally connected, and a plurality of core cavities are formed between the first C-beams 1 and the second C-beams 2, and the C-shaped opening end of the beam structure is provided with a flange folded toward the inner side of the core cavities, and the first C-beam and the second C-beam intersect vertically and horizontally to form a beam structure with a vertical and horizontal structure, and the opening directions of the first C-beam and the second C-beam are consistent, so that the overall opening direction of the beam structure is consistent.

[0035] An embodiment of the present invention provides a forming mold for forming a beam structure, such as Figure 1 As shown, the mold includes auxiliary tooling, multiple first core molds 3, and multiple second core molds 4. The first core mold 3 is a long strip structure, and the second core mold 4 is a cube structure. The first core mold and the second core mold are preferably made of pure metal material. The auxiliary tooling includes a base 6 and a side baffle 5. The side baffle 5 is installed and enclosed on the four sides of the upper surface of the base 6. An installation cavity is formed between the side baffle 5 and the upper surface of the base 6. The first core mold 3 and the second core mold 4 can be detachably installed in the installation cavity. The first core molds 3 are arranged perpendicular to each other, and the second core molds 4 are symmetrically distributed on both sides of each of the first core molds 3, wherein the first core mold 3 is used to pave the inner ring beam area of ​​the beam structure, and the second core mold 4 is used to pave the flange beam area of ​​the beam structure.

[0036] Furthermore, in an embodiment of the present invention, a plurality of first mounting positions and a plurality of second mounting positions are provided in the mounting cavity, and each of the first core molds 3 is detachably set at each of the first mounting positions through a first positioning pin, and each of the second core molds 4 is detachably set at each of the second mounting positions through a second positioning pin.

[0037] The embodiment of the present invention also provides an integrated forming method for manufacturing the beam structure, comprising the following forming steps:

[0038] (1) a rubber material is bonded to the surface of each first core mold 3 and subjected to a hot pressing vulcanization treatment, then a release cloth is laid on the surface of the rubber layer, and a plurality of prepregs cut into a shape are laid on the surface of the first core mold 3 on which the release cloths are laid, wherein the shape is a three-dimensional unfolded plan view shape designed according to the outer shape of the first core mold, and the first core mold 3 on which the prepregs are laid is vacuum pre-compacted, and the pre-compacted first core mold 3 is subjected to a hot pressing pre-curing treatment to obtain the pre-cured first core mold 3 for standby use;

[0039] Among them, with the C-shaped opening end of the beam structure as the upper end, the surface of the first core mold 3 includes the lower surface of the first core mold, the left side surface of the first core mold, the right side surface of the first core mold, the front side surface of the first core mold and the rear side surface of the first core mold; the surface of the first core mold 3 is vacuum pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid, the vacuum degree of the vacuum pre-compacting is not less than -70KPa, and the pre-compacting time is at least 5 minutes.

[0040] Furthermore, the hot pressing vulcanization treatment sets the hot pressing temperature to 170°C-185°C and the hot pressing pressure to 0.4MPa-0.7MPa; the hot pressing pre-curing treatment sets the hot pressing temperature to 50°C-80°C, the hot pressing time to 30min-60min, and the hot pressing pressure to 0.4MPa-0.7MPa.

[0041] (2) Each of the second core molds 4 is installed on each of the second installation positions of the auxiliary tooling, and then a plurality of prepregs cut into a shape are laid on the surface of the second core mold 4, wherein the shape is a three-dimensional unfolded plan view shape designed according to the outer shape of the second core mold, and the second core mold 4 with the prepregs laid thereon is vacuumed and pre-compacted,

[0042] Among them, taking the C-shaped open end of the beam structure as the upper end, the surface of the second core mold 4 includes the upper surface of the second core mold, the left side surface of the second core mold, the right side surface of the second core mold, the front side surface of the second core mold and the rear side surface of the second core mold; the surface of the second core mold 4 is vacuum pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid, the vacuum degree of the vacuum pre-compacting is not less than -70KPa, and the pre-compacting time is at least 5min.

[0043] Furthermore, the prepregs used in steps (1) and (2) are both carbon fiber composite materials, and the carbon fiber arrangement angles of the prepregs include 0°, 90°, 45° and -45°.

[0044] The number of layers of the prepreg material paved on the surface of the first core mold 3 is 18-20; the number of layers of the prepreg material paved on the surface of the second core mold 4 is 18-20.

[0045] (3) Installing the first core mold 3 after pre-curing in step (1) on the first installation position of the auxiliary tooling in step (2), so that the first core mold 3 and the second core mold 4 are combined to form a shaping tooling of the beam structure, packaging the auxiliary tooling with the shaping tooling, and then sending it into an autoclave for hot pressing and curing treatment. After the hot pressing and curing treatment is completed, demolding is performed to obtain the beam structure.

[0046] The curing temperature of the hot pressing curing treatment is 120° C.-150° C., the curing pressure is 0.4 MPa-0.7 MPa, and the curing time is at least 120 min.

[0047] The embodiment of the present invention Figure 2 The specific forming steps of the beam structure shown include:

[0048] (1) Material thawing: Take out the UHN10000 prepreg from the -18°C cold storage and thaw the prepreg in the clean room. Note that the prepreg needs to be kept sealed during thawing to avoid moisture absorption when the prepreg comes into contact with air during thawing, which will affect the quality of the prepreg.

[0049] (2) The prepreg is cut into a certain shape according to the structural requirements of the product by an automatic blanking machine, wherein the fiber arrangement angles of the prepreg include 0°, 90°, 45°, and -45°, such as 0° prepreg unidirectional tape and 45° prepreg unidirectional tape. Prepreg unidirectional tapes with different angles can be selected according to the stress orientation requirements of the product.

[0050] (3) Mold cleaning and assembly: Use acetone to clean the oil or stains on the surface of the mold (including the first core mold, the second core mold, the side baffle and the base) until there is no stain on the surface of the mold when wiping it with a clean rag. Then apply 3 layers of mold release agent on the surface of the mold to facilitate subsequent product demolding. Install the side baffles on the four sides of the base to enclose and form an installation cavity, wherein the installation cavity is designed with a first installation position and a second installation position for installing the first core mold and the second core mold, respectively.

[0051] (4) Pretreatment of the first core mold: The surface of the first core mold is polished, and then a layer of flexible rubber material is bonded thereto. The first core mold bonded with the rubber material is then sealed and bagged with a vacuum bag, the vacuum bag is evacuated and sealed, and finally the mold is placed in an autoclave for hot pressing, wherein the hot pressing temperature is set to 170°C-185°C, and the hot pressing pressure is set to 0.4MPa-0.7MPa, so that the rubber material is vulcanized during the hot pressing process, ensuring that the rubber material is in close contact with the surface of the first core mold. The rubber material is used to ensure the internal quality of the prepreg after molding, that is, to ensure the apparent quality of the inner surface of the product, such as a smooth and flat surface. After the hot pressing is completed, a layer of release cloth is laid on the surface of the rubber material on the surface of the first core mold for standby use.

[0052] (5) Laying the first core mold: Laying the prepreg material cut into shape on the surface of the first core mold, wherein the C-shaped open end of the beam structure is the upper end, and the surface of the first core mold includes the lower surface of the first core mold, the left side surface of the first core mold, the right side surface of the first core mold, the front side surface of the first core mold and the rear side surface of the first core mold. After the first layer of prepreg is laid, vacuum pre-compaction is performed once, and vacuum pre-compaction is performed once every 3-5 layers of subsequent laying. The number of paving layers of the first core mold is 20, and the specific operation method of vacuum pre-compaction is as follows: vacuumizing the first core mold after bagging and sealing at room temperature, with the vacuum degree not less than -70KPa, and the pre-compaction time is at least 5 minutes; placing the first core mold after all the layers are laid and pre-compacted in an autoclave for hot pressing, wherein the hot pressing temperature is set to 50℃-80℃, the hot pressing time is set to 30-60min, and the hot pressing heat is set to 0.4MPa-0.7MPa, to obtain a pre-cured first core mold for standby use.

[0053] (6) Pretreatment of the second core mold: The second core mold is fixed to the second installation position on the base through the second positioning pin and the positioning hole on the base. The second positioning pin is set on the second core mold, and the positioning hole is set on the base. The second positioning pin is inserted into the positioning hole to fix the second core mold on the second installation position of the base.

[0054] (7) Second core mold paving: The prepreg cut into shape is laid on the surface of the second core mold fixed on the base, wherein the C-shaped opening end of the beam structure is the upper end, and the surface of the second core mold includes the upper surface of the second core mold, the left side of the second core mold, the right side of the second core mold, the front side of the second core mold, and the rear side of the second core mold. After the first layer of prepreg is laid, vacuum pre-compacting is performed once, and then vacuum pre-compacting is performed once every 3-5 layers. The number of layers laid on the second core mold is the same as that of the first core mold, and the number of layers laid on the second core mold is also 20, so as to ensure that the thickness of each part of the same product is consistent. Among them, the specific operation method of vacuum pre-compacting the second core mold is: vacuumize the second core mold after bagging and sealing it at room temperature, and the vacuum degree is not less than -70KPa, and the pre-compacting time is at least 5 minutes.

[0055] (8) Solidification of the rough blank: The pre-cured first core mold obtained in the above step (5) is installed on the first installation position on the base through the cooperation of the first positioning pin and the positioning hole, so that the first core mold and the second core mold are combined to form a rough blank of the beam structure with a longitudinal and transverse structure. In the embodiment of the present invention, there are 9 first core molds and 20 second core molds, which are connected and combined to form a beam structure with a longitudinal and transverse structure. Figure 2 The rough beam structure is shown; then the base with the first core mold and the second core mold fixed is packaged and bagged, and sent into the autoclave for hot pressing and curing again, wherein the curing temperature is 120℃-150℃, the curing pressure is 0.4MPa-0.7MPa, and the curing time is at least 120min; after the curing is completed, the temperature is lowered and the pressure is released, and the mold is demolded to obtain a multi-grid structure beam structure product.

[0056] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A molding die, characterized in that: Used for forming a beam structure, the beam structure is composed of a plurality of first longitudinal C-shaped beams and a plurality of second transverse C-shaped beams connected orthogonally, and a plurality of core lattice cavities are formed between the first C-shaped beams and the second C-shaped beams, and the open end of the beam structure is provided with a flange folded toward the inner side of the core lattice cavity; The mold includes auxiliary tooling, multiple first core molds, and multiple second core molds. The first core mold is a long strip structure, and the second core mold is a cube structure. The auxiliary tooling includes a base and side baffles. The side baffles are installed and enclosed on the four sides of the upper surface of the base. An installation cavity is formed between the side baffles and the upper surface of the base. The first core mold and the second core mold are both detachably installed in the installation cavity. The first core molds are arranged perpendicular to each other, and the second core molds are symmetrically distributed on both sides of each of the first core molds, wherein the first core mold is used to pave the inner ring beam area of ​​the beam structure, and the second core mold is used to pave the flanged beam area of ​​the beam structure.

2. The molding die according to claim 1, characterized in that: A plurality of first mounting positions and a plurality of second mounting positions are provided in the mounting cavity. Each of the first core molds is detachably arranged at each of the first mounting positions via a first positioning pin, and each of the second core molds is detachably arranged at each of the second mounting positions via a second positioning pin.

3. An integrated molding method, using the molding die as claimed in claim 1 to mold the beam structure, characterized in that: The molding process includes the following steps: (1) bonding a rubber material to the surface of each first core mold and performing a hot-pressing vulcanization treatment, then laying a release cloth on the surface of the rubber layer, laying multiple layers of prepreg cut into shape on the surface of the first core mold laid with the release cloth, vacuuming and pre-compacting the first core mold with the prepreg, and performing a hot-pressing and pre-curing treatment on the pre-compacted first core mold to obtain the pre-cured first core mold for standby use; Wherein, with the C-shaped opening end of the beam structure as the upper end, the surface of the first core mold includes the lower surface of the first core mold, the left side surface of the first core mold, the right side surface of the first core mold, the front side surface of the first core mold and the rear side surface of the first core mold; The hot pressing vulcanization treatment sets the hot pressing temperature to 170°C-185°C and the hot pressing pressure to 0.4MPa-0.7MPa; (2) installing each of the second core molds at a corresponding position of the installation cavity of the auxiliary tooling, and then laying multiple layers of prepreg cut into shape on the surface of the second core mold, and vacuuming and pre-compacting the second core molds laid with the prepreg; Wherein, with the C-shaped opening end of the beam structure as the upper end, the surface of the second core mold includes the upper surface of the second core mold, the left side surface of the second core mold, the right side surface of the second core mold, the front side surface of the second core mold, and the rear side surface of the second core mold; (3) Installing the first core mold after pre-curing in step (1) at the corresponding position of the installation cavity of the auxiliary tooling in step (2), so that the first core mold and the second core mold are combined to form a shaping tooling of the beam structure, packaging the auxiliary tooling with the shaping tooling, and then sending it into an autoclave for hot pressing and curing treatment. After the hot pressing and curing treatment is completed, demolding is performed to obtain the beam structure.

4. The integrated molding method according to claim 3, characterized in that: The hot pressing temperature of the hot pressing pre-curing treatment in the step (1) is 50° C.-80° C., the hot pressing time is 30 min-60 min, and the hot pressing pressure is 0.4 MPa-0.7 MPa.

5. The integrated molding method according to claim 3, characterized in that: The prepreg is a carbon fiber composite material, and the carbon fiber arrangement angles of the prepreg include 0°, 90°, 45° and -45°.

6. The integrated molding method according to claim 3, characterized in that: The number of layers of the prepreg material paved on the surface of the first core mold is 18-20; the number of layers of the prepreg material paved on the surface of the second core mold is 18-20.

7. The integrated molding method according to claim 3, characterized in that: The surface of the first core mold is vacuumed and pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid; The surface of the second core mold is vacuumed and pre-compacted after the first layer of the prepreg is laid, and after every 3-5 layers of the prepreg are laid.

8. The integrated molding method according to claim 7, characterized in that: The vacuum degree of the vacuum pre-compaction is not less than -70 KPa, and the pre-compaction time is at least 5 minutes.

9. The integrated molding method according to claim 3, characterized in that: The curing temperature of the hot pressing curing treatment in the step (3) is 120° C.-150° C., the curing pressure is 0.4 MPa-0.7 MPa, and the curing time is at least 120 min.

10. A beam structure, characterized in that: The product is manufactured by the molding method as described in any one of claims 3 to 9.

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