Manufacturing method for hollow parts

Abstract

This invention provides a method for manufacturing hollow parts that can easily produce hollow parts made of fiber composite material using a resin core. [Solution] The method for manufacturing a hollow part includes the steps of: (S1) manufacturing a resin core having a surface shape corresponding to the inner surface shape of the hollow part using a 3D printer; (S2) laminating a sheet-like prepreg onto the surface of the resin core; (S3, S4) setting the resin core with the laminated prepreg onto an outer mold and clamping the mold; (S6) heating or pressurizing the outer mold in an autoclave to form an intermediate of the hollow member; (S9) opening the outer mold and removing the intermediate of the hollow member from the outer mold; and (S10) dissolving any remaining resin core in the intermediate of the hollow member using an alkaline solvent.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a hollow part made of a fiber composite material.

Background Art

[0002] Conventionally, a method has been proposed for manufacturing a hollow part having a complex hollow part cross-section such as an engine part for a racing vehicle using carbon fiber reinforced resin (CFRP). In the conventional manufacturing method, a hollow part (final molded product) made of carbon fiber reinforced resin is manufactured by using a gypsum core and a carbon fiber reinforced resin sheet. The gypsum core is manufactured by creating a female mold with a split mold block and pouring and curing liquid gypsum (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, for engine parts for racing vehicles and the like, it has been required to manufacture hollow parts having a more complex hollow part cross-section. However, with the conventional manufacturing method, it has not been easy to manufacture a core having a more complex shape with gypsum. When using a 3D printer, a core having a more complex shape can be easily manufactured with resin. However, when simply using a resin core, since the strength is lower than that of a gypsum core, there has been a problem that the resin core is deformed and crushed when heated and pressurized in an autoclave or an oven, and a hollow part (final molded product) cannot be manufactured.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a hollow part that can easily manufacture a hollow part made of a fiber composite material using a resin core. [Means for solving the problem]

[0006] The present invention provides a method for manufacturing a hollow component made of a fiber composite material, comprising the steps of: using an alkali-soluble resin that is soluble in an alkaline solvent as a material, manufacturing a resin core having a surface shape corresponding to the inner surface shape of the hollow component using a 3D printer; laminating a sheet-like prepreg, in which fibers are impregnated with resin, onto the surface of the resin core; setting the resin core with the laminated sheet-like prepreg onto an outer mold having a surface shape corresponding to the outer surface shape of the hollow component, and clamping the outer mold; heating or pressurizing the outer mold in an autoclave to form an intermediate of the hollow component with the resin core remaining inside; opening the outer mold and removing the intermediate of the hollow component from the outer mold after the molding of the intermediate of the hollow component is completed; and dissolving the resin core remaining in the intermediate of the hollow component using an alkaline solvent.

[0007] This manufacturing method allows for the easy production of hollow parts made of fiber composite materials using a resin core. In this case, even resin cores with more complex shapes can be easily manufactured using a 3D printer. Furthermore, since the resin core is made of alkali-soluble resin, it can be easily dissolved using an alkaline solvent. In addition, by setting the resin core in the outer mold and clamping it, it is possible to prevent the resin core from deforming and collapsing when heated and pressurized in an autoclave. This allows for accurate transfer of the surface shape of the outer mold (mold surface shape) to the outer surface shape of the hollow part, and also allows for accurate transfer of the surface shape of the resin core to the inner surface shape of the hollow part. As the fiber composite material, for example, carbon fiber reinforced polymer (CFRP) or other carbon fiber composite materials can be used.

[0008] Furthermore, in the method for manufacturing hollow parts of the present invention, the resin core is provided with a positioning section where the sheet-like prepreg is not laminated, and the outer mold is provided with a corresponding positioning section at a position corresponding to the positioning section, and when the resin core is set in the outer mold, the positioning section is fixed to the corresponding positioning section, thereby positioning the resin core relative to the outer mold.

[0009] With this configuration, when the resin core is set in the outer mold, the resin core is positioned relative to the outer mold by the positioning part of the resin core and the corresponding positioning part of the outer mold. This prevents the formation of a difference in wall thickness in the resin core due to the difference in expansion coefficients between the resin core and the outer mold when the outer mold (the outer mold with the resin core set in it) is heated and pressurized in an autoclave.

[0010] Furthermore, in the method for manufacturing hollow parts of the present invention, the outer mold is equipped with a positioning jig that is positioned relative to the outer mold, and after setting the resin core in the outer mold, the positioning jig is fixed to the resin core and the positioning jig is fixed to the outer mold, thereby positioning the resin core relative to the outer mold.

[0011] In this configuration, after the resin core is set in the outer mold, a positioning jig positions the resin core relative to the outer mold. This prevents the formation of a difference in wall thickness in the resin core due to the difference in expansion coefficients between the resin core and the outer mold when the outer mold (with the resin core set in it) is heated and pressurized in an autoclave.

[0012] Furthermore, in the method for manufacturing a hollow component of the present invention, in the step of forming the intermediate body of the hollow member, the outer mold may be vacuum-packed and heated or pressurized in an autoclave to form the intermediate body of the hollow member in which the resin core remains inside, and in the step of removing the intermediate body of the hollow member, the vacuum packing may be released and the outer mold may be opened to remove the intermediate body of the hollow member from the outer mold.

[0013] With this configuration, by heating and pressurizing the outer mold (the outer mold with the resin core set inside) in a vacuum-packed state in an autoclave, the surface shape of the outer mold (mold surface shape) is accurately transferred to the outer surface shape of the hollow component, and the surface shape of the resin core is accurately transferred to the inner surface shape of the hollow component.

[0014] Furthermore, in the method for manufacturing hollow components of the present invention, the surface of the resin core may be subjected to a surface treatment to improve the surface accuracy of the surface.

[0015] With this configuration, since the surface of the resin core is surface-treated, the surface shape of the resin core is transferred more accurately to the inner shape of the hollow part. Surface treatment (a process to improve the surface accuracy) includes, for example, applying tape to the surface of the resin core, filling in depressions on the surface of the resin core with putty or resin and polishing, or applying a resin dipping treatment to the surface of the resin core.

[0016] Furthermore, in the method for manufacturing hollow parts of the present invention, the outer mold comprises a base mold and a slide mold that can slide relative to the base mold and be clamped, and in the step of laminating the sheet-like prepreg, the sheet-like prepreg is laminated at the thickness before heating and pressurizing, and in the step of clamping the outer mold, the slide mold may be incompletely clamped, and by heating or pressurizing the outer mold in an autoclave, the thickness of the sheet-like prepreg may decrease from that before heating and pressurizing, and the slide mold may be completely clamped.

[0017] This configuration, by using a sliding type (a sliding type that can slide relative to the base type to clamp the mold), makes it possible to accommodate the decrease in the thickness of the prepreg (sheet-shaped prepreg) when it is heated and pressurized in the autoclave compared to before heating and pressurizing. [Effects of the Invention]

[0018] According to the present invention, hollow parts made of fiber composite material can be easily manufactured using a resin core.

Brief Description of the Drawings

[0019] [Figure 1] It is a flowchart showing the process of the manufacturing method of the hollow part in this embodiment. [Figure 2] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (resin inner mold produced by a 3D printer). [Figure 3] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the state where prepreg is laminated on the resin inner mold). [Figure 4] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the state where the resin inner mold is set in the outer mold). [Figure 5] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the state where the slide mold is slid). [Figure 6] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the state where the outer mold is clamped). [Figure 7] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the state where the outer mold is opened). [Figure 8] It is an explanatory diagram of the manufacturing method of the hollow part in this embodiment (the hollow part after the resin inner mold is dissolved). [Figure 9] It is a diagram showing an example of vacuum packing in this embodiment. [Figure 10] It is a diagram showing another example of vacuum packing in this embodiment. [Figure 11] It is a diagram showing an example of the positioning of the resin inner mold with respect to the outer mold in this embodiment. [Figure 12] It is a diagram showing another example of the positioning of the resin inner mold with respect to the outer mold in this embodiment.

Embodiments for Carrying Out the Invention

[0020] The method for manufacturing hollow parts according to embodiments of the present invention will be described below with reference to the drawings. In this embodiment, an example of a method for manufacturing hollow parts used in the manufacture of engine parts for racing vehicles will be provided.

[0021] A method for manufacturing a hollow part according to an embodiment of the present invention will be described with reference to the drawings. Figure 8 is a flowchart showing the flow of the manufacturing method for a hollow part according to this embodiment, and Figures 1 to 7 are explanatory diagrams showing the manufacturing method for a hollow part according to this embodiment. In this embodiment, an example is given of manufacturing a hollow part using carbon fiber reinforced resin (CFRP).

[0022] When manufacturing hollow parts made of CFRP (for example, engine parts for racing cars), first, as shown in Figure 1, a resin core 1 is fabricated using a 3D printer with an alkali-soluble resin that is soluble in an alkaline solvent (see S1, Figure 2). This resin core 1 has a surface shape that corresponds to the inner surface shape of the hollow part (see Figure 8). As the alkali-soluble resin, known materials such as Stratasys' "ST-130", polyvinyl alcohol resin (PVA), and polycaprolactone resin (PCL) can be used.

[0023] In the example shown in Figure 2, the resin core 1 is depicted as solid, but the resin core 1 may also be hollow. Making the resin core 1 hollow allows for the saving of resin by the amount of the hollow core. Furthermore, the time required for dissolving the resin core 1 (S10) can be shortened.

[0024] Furthermore, the surface of the resin core 1 may be subjected to a surface treatment (not shown) to improve the surface accuracy. Surface treatments (treatments to improve surface accuracy) include, for example, applying tape to the surface of the resin core 1, filling in depressions on the surface of the resin core 1 with putty or resin and polishing, or performing a resin dipping treatment on the surface of the resin core 1.

[0025] Next, a sheet-like prepreg (CFRP prepreg) 2, in which carbon fibers are impregnated with resin, is laminated onto the surface of the resin core 1 (S2, see Figure 3). As the CFRP prepreg 2, known materials such as Toray Industries, Inc.'s "Torayca®" and Mitsubishi Chemical Corporation's "Pyrofil®" prepreg materials can be used. The resin core 1 is provided with a positioning section 3 where the CFRP prepreg 2 is not laminated. The positioning section 3 of the resin core 1 can also be described as the part of the resin core 1 where the CFRP prepreg 2 is not laminated.

[0026] Next, the resin core 1, on which the CFRP prepreg 2 is laminated, is set into the outer mold 4 (S3, see Figure 4). The mold surface of the outer mold 4 has a surface shape (mold surface shape) that corresponds to the outer surface shape of the hollow part. The outer mold 4 is made of metal, for example. The outer mold 4 is composed of a base mold 5 and a plurality of slide molds 6, and the slide molds 6 can slide relative to the base mold 5 to clamp the mold (see Figure 5). The resin core 1, on which the CFRP prepreg 2 is laminated, is set into the base mold 5 of the outer mold 4.

[0027] Next, the slide mold 6 is slid relative to the base mold 5 to clamp the outer mold 4 (see S4, Figures 5 and 6). The outer mold 4 is provided with a corresponding positioning part 7 at a position corresponding to the positioning part 3. When the resin core 1 is set in the outer mold 4 and the mold is clamped, the positioning part 3 is fixed to the corresponding positioning part 7, and the resin core 1 is positioned relative to the outer mold 4 (see Figure 11).

[0028] Note that the positioning section 3 and the corresponding positioning section 7 do not necessarily have to be provided. For example, if the resin core 1 is hollow, the resin core 1 can be positioned relative to the outer mold 4 by using a positioning jig J that is positioned relative to the outer mold 4. After setting the resin core 1 in the outer mold 4, the positioning jig J is fixed to the resin core 1 and the positioning jig J is fixed to the outer mold 4, thereby positioning the resin core 1 relative to the outer mold 4 (see Figure 12).

[0029] Furthermore, if the resin core 1 has a body portion 10 extending in the longitudinal direction and a chimney portion 11 branching from the body portion 10, the body portion 10 and the chimney portion 11 may be constructed as separate parts. In that case, a positioning portion 3 may be provided on the chimney portion 11 to position the chimney portion 11 on the outer mold 4 (see Figure 11), or a positioning jig J may be fixed to the chimney portion 11 to position the chimney portion 11 on the outer mold 4 (see Figure 12). By making the body portion 10 and the chimney portion 11 separate parts, it is possible to prevent the chimney portion 11 from following the thermal expansion of the body portion 10 when heated and pressurized (S6) in the autoclave.

[0030] Next, the outer mold 4 (the outer mold 4 with the resin core 1 set and clamped) is vacuum-packed (S5). If the resin core 1 is solid, the outer mold 4 (the outer mold 4 with the resin core 1 set and clamped) is covered with packing film F and vacuum-packed (see Figure 9). If the resin core 1 is hollow, the outer mold 4 (the outer mold 4 with the resin core 1 set and clamped) is covered with packing film F, and the packing film F is inserted into the hollow portion of the resin core 1 and vacuum-packed (see Figure 10). Known methods can be used for these vacuum packing processes.

[0031] Next, the outer mold 4 (the outer mold 4 with the resin core 1 set and clamped) is heated and pressurized in an autoclave to form an intermediate 8 of the hollow member 9 with the resin core 1 remaining inside (S6). The heating temperature and pressurizing pressure in the autoclave are set according to the curing rate of the material, for example, within the range of 60°C to 135°C and 0 MPa to 0.8 MPa. The heating and pressurizing time in the autoclave (material curing cycle) is set to the time recommended by the manufacturer as the time required to reach curing, according to the heating temperature and pressurizing pressure (for example, 3 to 8 hours for 60°C to 135°C and 0 MPa to 0.8 MPa).

[0032] In this embodiment, the thickness of the CFRP prepreg 2 is greater before heating and pressurizing in the autoclave (S6) than after heating and pressurizing. Therefore, when laminating the CFRP prepreg 2 onto the surface of the resin core 1, the CFRP prepreg 2 with the thickness before heating and pressurizing is laminated (S2), and when clamping the outer mold 4, the slide mold 6 is not completely clamped (S4). Subsequently, by heating and pressurizing the outer mold 4 in the autoclave (S6), the thickness of the CFRP prepreg 2 decreases compared to before heating and pressurizing, and the slide mold 6 is completely clamped (see Figures 9 and 10).

[0033] After heating and pressurizing are completed, heat dissipation and pressure release are performed inside the autoclave (S7). The cooling rate during heat dissipation and pressure release inside the autoclave is, for example, 3 to 5°C / min, and the average pressure reduction is, for example, 0.05 to 0.07 MPa. After heat dissipation and pressure release are completed, the packing film F covering the outer mold 4 is opened to release the vacuum packing (S8), the slide mold 6 is slid open to open the outer mold 4, and the intermediate body 8 of the hollow member 9 (the hollow member 9 with the resin core 1 remaining inside) is removed from the outer mold 4 (S9, see Figure 7).

[0034] Subsequently, the resin core 1 remaining in the intermediate 8 of the hollow member 9 is dissolved using an alkaline solvent (S10). When dissolving the resin core 1, the time required for dissolution can be shortened by performing ultrasonic cleaning at the same time. As the alkaline solvent, known solvents such as caustic soda solution (NaOH) or KJ support removal solution manufactured by Kao Corporation can be used. In this way, a CFRP hollow member 9 (a hollow member 9 in which the resin core 1 does not remain inside) is obtained (see Figure 8).

[0035] According to the manufacturing method for hollow parts of this embodiment, hollow parts made of CFRP can be easily manufactured using a resin core 1. In this embodiment, even if the resin core 1 has a more complex shape, it can be easily manufactured using a 3D printer. Furthermore, since the resin core 1 is made of alkali-soluble resin, it can be easily dissolved using an alkaline solvent. In addition, by setting the resin core 1 in the outer mold 4 and clamping it, it is possible to prevent the resin core 1 from deforming and collapsing when heated and pressurized in the autoclave. As a result, the surface shape of the mold surface of the outer mold 4 (mold surface shape) can be accurately transferred to the outer surface shape of the hollow part, and the surface shape of the resin core 1 can be accurately transferred to the inner surface shape of the hollow part.

[0036] Furthermore, in this embodiment, as shown in Figure 11, when the resin core 1 is set in the outer mold 4, the resin core 1 is positioned relative to the outer mold 4 by the positioning part 3 of the resin core 1 and the corresponding positioning part 7 of the outer mold 4. This prevents the occurrence of a difference in wall thickness in the resin core 1 due to the difference in expansion coefficients between the resin core 1 and the outer mold 4 when the outer mold 4 (the outer mold 4 in which the resin core 1 is set) is heated and pressurized in an autoclave.

[0037] Alternatively, as shown in Figure 12, after the resin core 1 is set in the outer mold 4, the resin core 1 is positioned relative to the outer mold 4 by the positioning jig J. This prevents the formation of a difference in wall thickness in the resin core 1 due to the difference in expansion coefficients between the resin core 1 and the outer mold 4 when the outer mold 4 (the outer mold 4 with the resin core 1 set in it) is heated and pressurized in an autoclave.

[0038] Furthermore, in this embodiment, as shown in Figures 9 and 10, by heating and pressurizing the outer mold 4 (outer mold 4 with the resin core 1 set inside) in an autoclave while it is vacuum-packed, the surface shape of the mold surface of the outer mold 4 is accurately transferred to the outer surface shape of the hollow component, and the surface shape of the resin core 1 is accurately transferred to the inner surface shape of the hollow component.

[0039] Furthermore, in this embodiment, since the surface of the resin core 1 is surface-treated, the surface shape of the resin core 1 is transferred more accurately to the inner surface shape of the hollow part. Surface treatment (a treatment to improve the surface accuracy of the surface) includes, for example, applying tape to the surface of the resin core 1, filling in recesses on the surface of the resin core 1 with putty or resin and polishing, or performing a resin dipping treatment on the surface of the resin core 1.

[0040] Furthermore, in this embodiment, as shown in Figures 9 and 10, by using a slide mold 6 (a slide mold 6 that can slide relative to the base mold 5 and be clamped), it becomes possible to accommodate the decrease in the thickness of the CFRP prepreg 2 when it is heated and pressurized in the autoclave compared to before heating and pressurizing.

[0041] Although embodiments of the present invention have been described above by example, the scope of the present invention is not limited to these, and modifications and alterations can be made within the scope described in the claims depending on the purpose.

[0042] For example, in the above embodiment, an example was described in which the outer mold is heated and pressurized in an autoclave in step S6, but the scope of the present invention is not limited to this. Modes in which the outer mold is only heated in an autoclave (heated without pressurizing) and modes in which the outer mold is only pressurized in an autoclave (pressurized without heating) can also be implemented in the same manner. [Industrial applicability]

[0043] As described above, the method for manufacturing hollow parts according to the present invention has the effect of easily manufacturing hollow parts made of fiber composite material using a resin core, and is useful for manufacturing engine parts for racing vehicles and the like. [Explanation of Symbols]

[0044] 1. Resin core 2. CFRP prepreg (sheet-type prepreg) 3 Positioning section 4 Outer mold 5 Base type 6 Slide type 7. Corresponding positioning section 8 Intermediates 9 Hollow member 10 Torso 11 Chimney section J Positioning jig F Packing film

Claims

1. A method for manufacturing hollow parts made of fiber composite material, A process of using an alkali-soluble resin, which is soluble in an alkaline solvent, as the material to manufacture a resin core having a surface shape corresponding to the inner surface shape of the hollow part, using a 3D printer, The process involves laminating a sheet-like prepreg, in which fibers are impregnated with resin, onto the surface of the aforementioned resin core, The process involves setting the resin core, which is made up of laminated sheet-like prepregs, into an outer mold having a surface shape corresponding to the outer surface shape of the hollow part, and then clamping the outer mold. A step of heating or pressurizing the outer mold in an autoclave to form an intermediate of the hollow member in which the resin core remains inside, After the molding of the intermediate hollow member is completed, the outer mold is opened and the intermediate hollow member is removed from the outer mold. A step of dissolving the resin core remaining in the intermediate of the hollow member using an alkaline solvent, A method for manufacturing hollow parts, including [the specified part].

2. The resin core is provided with a positioning section where the sheet-like prepreg is not laminated. The outer mold is provided with a corresponding positioning section at a position corresponding to the positioning section. The method for manufacturing a hollow part according to claim 1, wherein when the resin core is set in the outer mold, the positioning part is fixed to the corresponding positioning part, and the resin core is positioned relative to the outer mold.

3. The outer mold is equipped with a positioning jig that is positioned relative to the outer mold. A method for manufacturing a hollow part according to claim 1, wherein after setting the resin core in the outer mold, the positioning jig is fixed to the resin core and the positioning jig is fixed to the outer mold, thereby positioning the resin core with respect to the outer mold.

4. In the process of forming the intermediate of the hollow member, the outer mold is vacuum-packed and heated or pressurized in an autoclave to form the intermediate of the hollow member in which the resin core remains inside. The method for manufacturing a hollow component according to claim 1, wherein in the step of removing the intermediate of the hollow component, the vacuum packing is released and the outer mold is opened, and the intermediate of the hollow component is removed from the outer mold.

5. The method for manufacturing a hollow component according to claim 1, wherein the surface of the resin core is subjected to a surface treatment to improve the surface accuracy of the surface.

6. The outer mold comprises a base mold and a sliding mold that can slide relative to the base mold and be clamped. In the process of laminating the sheet-like prepreg, the sheet-like prepreg with the thickness before heating and pressurizing is laminated. In the process of clamping the outer mold, the slide mold is not clamped completely. The method for manufacturing a hollow part according to claim 1, wherein the thickness of the sheet-like prepreg is reduced by heating or pressurizing the outer mold in an autoclave, and the slide mold is completely clamped.

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