JP6504993B2 - Method of manufacturing curved sandwich structure - Google Patents

Description

  The present invention relates to a method of manufacturing a curved sandwich structure using a fiber reinforced plastic material as a skin material.

  BACKGROUND ART In recent years, fiber reinforced plastic materials (hereinafter referred to as FRP) have been applied in a wide range of fields, taking advantage of the properties of light weight, high strength and high rigidity. Among them, a sandwich structure in which an FRP is used as a skin material and a lightweight core material is sandwiched between the skin materials and is integrated is widely known as a method for enhancing rigidity while efficiently using the FRP.

  As applications of such sandwich structures, for example, as exemplified in satellite chassis structures, reflectors for antennas, and radomes, they have been used particularly in space and communication applications where lightness and high rigidity are required. . On the other hand, in recent years, such sandwich structures are being used also in the structure of moving bodies centered on aircraft and cars. In addition to the above, the present invention can also be applied to the structure of a moving object such as a railway vehicle or an elevator.

  With regard to materials and forming methods, in space and communication applications, an FRP sandwich structure having a honeycomb material as a core material is formed (autoclave forming method) with a pressure vessel called an autoclave. However, in the autoclave molding method, there is a problem that the material cost and the molding cost are high, and it is required to reduce the material cost and the molding cost while expanding the application of the FRP sandwich structure.

  Therefore, a vacuum impregnation molding method has been proposed as a low-cost molding method of FRP to replace the autoclave molding method. The vacuum impregnation molding method is a molding method in which a resin cloth is impregnated into a fiber cloth obtained by making fibers into a woven form by using atmospheric pressure.

  As a specific procedure, first, a fiber cloth is laminated on a mold, and a peel ply having releasability and a flow medium for diffusing the resin in the in-plane direction are arranged in the order of peel ply and flow medium. Stack.

  Next, an air-tight sealant is placed around the mold on which the fiber cloth, the peel ply, and the flow media are laminated, and the inlet and the suction port are set, and the whole is covered with a bagging film and sealed. Next, the suction port is connected to a vacuum pump to vacuum suction the inside of the bagging film, and then the injection port is connected to a resin tank to impregnate the resin by atmospheric pressure, and the resin is cured to obtain a molded skin material. .

  The vacuum impregnation molding method is a method that can be molded at low cost because it does not require extensive equipment such as an autoclave or a strong mold. As for the material, it is possible to use a low cost and light weight resin foam material as a core material in place of the honeycomb material. This enables low-cost forming of the FRP sandwich structure.

  Here, in space and communication applications, curved surface-shaped members are required as represented by the central cylinder, which is the center of the satellite casing structure, a parabolic antenna reflector, and a radome. These members have shape stability and dimensional accuracy to withstand external loads and temperature differences in order to satisfy required specification values such as positional accuracy between devices attached to the housing structure and directivity accuracy of radio waves. It will be necessary. Even when applied to a moving body, the dimensional accuracy of the member affects the aerodynamic characteristics of the moving body and the strength to endure external loads, so it is necessary to satisfy the required value of the dimensional accuracy.

  In the case of the planar shape, it is considered that the flatness of the molded product can be relatively easily improved by improving the flatness of the mold. However, in the case of the curved surface, there is a problem that the shape is three-dimensionally changed due to the cure shrinkage of the resin, and a desired dimensional accuracy can not be obtained.

  Therefore, when forming an FRP sandwich structure using a foam material as a core material, a foam core material previously processed into a desired curved surface shape is used as a mold, and the skin material is integrated with the core material simultaneously with molding. (See, for example, Patent Document 1). In this method, rigidity is increased by integrating the skin material and the core material, and a curved sandwich structure having desired dimensional accuracy can be obtained by suppressing deformation due to curing shrinkage of the resin in the skin material. it can.

  In the method of manufacturing a curved sandwich structure disclosed in Patent Document 1, a polyetherimide resin foam is machined into a curved surface, and a prepreg is laminated on one surface to perform molding and bonding. Thereafter, the other surface is processed so that the core material has a constant thickness, and the prepreg is laminated to perform molding and adhesion.

  According to this method, a polyetherimide resin foam processed into a desired shape is used as a mold, a prepreg is laminated on the mold, and molding and bonding are performed to obtain a curved surface with desired dimensional accuracy. Sandwich structures can be obtained.

JP 2002-292772 A

However, the prior art has the following problems.
In the method of producing a curved sandwich structure disclosed in Patent Document 1, the prepreg needs to be shaped by heating and pressing with an autoclave. In addition, even if the prepreg is processed to a desired dimensional accuracy at normal temperature, the sandwich structure is deformed by the molding temperature and molding pressure of the prepreg. As a result, there is a problem that desired dimensions can not be obtained after molding.

  When the sandwich structure is used as a member requiring a mirror surface accuracy such as an antenna reflector, when the foam material is formed as a mold, the surface of the foam material has irregularities, and the irregularities are exposed and the desired mirror surface accuracy is There was also a problem that it could not be obtained.

  Patent Document 1 also discloses a method of forming a skin material in advance and then bonding. However, if a skin material molded to a desired dimensional accuracy in advance is bonded with a cold-setting adhesive, thermal deformation does not occur, but it is necessary to mold the skin material alone in advance. Since the skin material alone is thin, its rigidity is small, and it is deformed by the temperature difference between the molding temperature and the normal temperature or the cure shrinkage of the resin. For this reason, it is very difficult to form the skin material alone to a desired dimensional accuracy.

  Here, the case where vacuum impregnation molding method is applied is considered in order to reduce molding cost. In the case of a vacuum impregnation molding method, thermal deformation due to a temperature difference associated with the autoclave molding method can be prevented by molding using a room temperature curing resin.

  However, when using a foam material as a shaping | molding die, the problem that a mirror surface precision is not obtained by the surface asperity of a foam material is not solved. In particular, since the vacuum impregnation molding method laminates the peel ply and the flow media on the fiber cloth, it is difficult to obtain the mirror surface accuracy of the foam material more than the autoclave molding method.

  In addition, even with a cold-setting resin, deformation occurs due to curing shrinkage, so it is also difficult to satisfy the dimensional accuracy with the skin material alone.

  The present invention has been made to solve the problems as described above, and it is possible to obtain a desired mirror surface accuracy and to reduce a molding cost without using an autoclave molding method. Provides a manufacturing method of

  According to the method of manufacturing a curved sandwich structure according to the present invention, a convex curved surface portion having a desired mirror surface accuracy, and a side surface portion extending downward from an outer peripheral portion of the convex curved surface portion when the convex curved surface portion is directed vertically upward. A method for producing a curved sandwich structure, which is integrally molded by covering the periphery of a foamed core material with a skin material of fiber reinforced plastic using a convex mold having When laminating the first fiber cloth on top of the first fiber cloth, by fixing the end of the first fiber cloth to the side surface, after the previous step of bringing the first fiber cloth into tight contact with the convex curved surface portion, Is impregnated into the first fiber cloth and cured to form a first skin material having a first curved surface skin formed on the convex curved surface and a first rib formed on the side surface. Forming a first skin material forming step, forming on a convex curved surface portion A core material which adheres on the first curved surface skin part a foamed core material which has been curved so as to conform to the upper surface shape of the first curved surface skin part and whose outer peripheral part reaches the first rib part in advance. In the bonding step, when laminating the second fiber cloth so as to cover the upper surface portion and the outer peripheral portion corresponding to the surface excluding the surface in contact with the first curved surface skin portion in the foamed core material, the end portion of the second fiber cloth By fixing the second fiber cloth to the upper surface portion and the outer peripheral portion of the foam core material by fixing the first fiber portion to the first rib portion, the resin is impregnated in the second fiber cloth and cured. A second surface material is formed, having a second curved surface skin portion formed on the upper surface portion of the foam core material, and a second rib portion formed over the outer periphery of the foam core material and over the first rib portion. 2 in the skin material forming step, and in the side portion of the convex mold A portion formed by stacking the second rib portion and the second rib portion, and the portion projecting vertically downward of the first curved surface skin portion along the curved surface in contact with the convex curved surface portion in the first curved surface skin portion And removing the protrusion.

  According to the present invention, the desired mirror surface accuracy can be obtained by impregnating the resin and curing it in a state in which the first fiber cloth is in close contact with the convex mold having the convex curved surface portion having the desired mirror surface accuracy. The first skin material having is formed. In addition, after bonding a foam core material, which has been subjected to processing to conform to the curved surface of the first skin material, onto the first skin material, the upper surface portion and the outer periphery of the foam core material and the first skin material The second surface material is formed by impregnating and curing the resin in a state in which the second fiber cloth is in close contact with the outer peripheral part of the second fiber cloth to complete the curved sandwich structure. In this manner, the first skin material, the foam core material, and the second skin material are sequentially laminated on the convex mold having a desired mirror surface accuracy, without using the autoclave molding method. It is possible to provide a method for manufacturing a curved sandwich structure which can obtain desired mirror surface accuracy and reduce molding cost.

It is a perspective view which shows a curved surface FRP sandwich structure. It is sectional drawing which shows the curved-surface-form FRP sandwich structure of FIG. It is a perspective view showing a convex mold used for molding of a curved surface FRP sandwich structure. It is sectional drawing which shows the state which laminated | stacked the 1st fiber cloth on the convex mold. It is a perspective view which shows the state which laminated | stacked the 1st fiber cloth on the convex mold. It is a perspective view which shows the state which is closely_contact | adhering a 1st fiber cloth on a convex mold. It is sectional drawing which shows the state which laminated | stacked the peel ply and the flow media on the 1st fiber cloth. It is sectional drawing which shows the 1st shaping | molding apparatus which shape | molds a 1st FRP surface material. It is sectional drawing which shows the state which is inject | pouring liquid resin in the 1st shaping | molding apparatus in a vacuum pressurization state. It is sectional drawing which shows the 1st FRP surface material which removed all the submaterials after liquid resin hardening. It is sectional drawing which shows the state which apply | coated resin for adhesion | attachment on the surface of a 1st curved-surface outer skin part. It is sectional drawing which shows the state which installed the foam core material which apply | coated resin for adhesion | attachment to the concave side on the 1st curved-surface outer skin part. It is sectional drawing which shows the state which laid the sealant in the side part of a convex mold, installed the suction port, overlapped the bagging film on the foam core material, and sealed the outer edge part with the sealant. It is sectional drawing which shows the state which removed all the submaterials, after resin for adhesion | attachment hardens | cures. It is sectional drawing which shows the state which laminated | stacked the 2nd fiber cloth so that a foaming core material might be covered. When the outer peripheral part of the foam core material does not reach the rib part, the second fiber cloth is stretched against the concave corner formed by the outer peripheral part of the foam core material and the first curved surface skin part 2a FIG. It is sectional drawing which shows the state which laminated | stacked the peel ply and the flow media on the 2nd fiber cloth. It is sectional drawing which shows the 2nd shaping | molding apparatus which shape | molds 2nd FRP surface material. It is sectional drawing which shows the state which is inject | pouring resin for injection | pouring in a 2nd shaping | molding apparatus in a vacuum pressurization state. After hardening of the resin for injection | pouring, all auxiliary materials are removed and it is sectional drawing which shows the state which demolded the molded object from the convex mold. It is sectional drawing which shows the curved-surface-form FRP sandwich structure which removed the burr | flash. It is sectional drawing in the symmetry plane of the convex mold used in Embodiment 2 of this invention. FIG. 23 is a perspective view showing a curved FRP sandwich structure molded using the convex mold of FIG. 22. It is a figure which shows the rotation paraboloid which obtains the convex-shaped curved-surface part of FIG. It is sectional drawing in a surface perpendicular | vertical to the axial direction of the convex mold used in Embodiment 3 of this invention. FIG. 26 is a perspective view showing a curved FRP sandwich structure molded using the convex mold of FIG. 25.

  Hereinafter, preferred embodiments of the method for producing a curved sandwich structure according to the present invention will be described with reference to the drawings. In the embodiment of the present invention, since the FRP is used as the surface material, the curved sandwich structure is described as a curved FRP sandwich.

Embodiment 1
The curved FRP sandwich structure according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a curved FRP sandwich structure. FIG. 2 is a cross-sectional view showing the curved FRP sandwich structure of FIG.

  As shown in FIGS. 1 and 2, in the curved FRP sandwich structure 1, the surfaces facing each other are disposed at a desired distance, and one surface is concave and the other surface is convex. . Therefore, the curved FRP sandwich structure 1 has a curved shape having a desired thickness distribution. The thickness of the curved FRP sandwich structure 1 may not be constant, and the thickness of the end portion may be 0, that is, the outer peripheral portion may be linear instead of planar.

  The curved FRP sandwich structure 1 is a sandwich structure using FRP as a surface material. That is, the curved FRP sandwich structure 1 comprises a first FRP skin material (first skin material) 2 forming a concave surface, a second FRP skin material (second skin material) 3 forming a convex surface, and a second It is comprised by the foam core material 4 pinched | interposed into the FRP surface material 2 of 1, and the 2nd FRP surface material 3. FIG. The first FRP skin material 2, the second FRP skin material 3, and the foam core material 4 are integrated by an adhesive. The foamed core material 4 has a curved shape having a desired thickness distribution. The thickness of the foamed core material 4 may not be constant, and the thickness of the end portion may be 0, that is, the outer peripheral portion may be linear instead of planar.

  The first FRP skin material 2 is bonded to the concave side of the foam core material 4. Further, the surface of the first FRP skin material 2, that is, the surface not bonded to the foamed core material 4 is a curved surface that satisfies a desired mirror surface accuracy.

  The second FRP skin material 3 is bonded so as to cover the convex side of the foam core 4 and the side surface of the foam core 4. Therefore, the foam core material 4 is covered with the first FRP skin material 2 and the second FRP skin material 3 and there is no exposure to the outside.

  The second FRP skin material 3 is also bonded to the convex side of the foam core 4 and to the side surface of the foam core 4. Therefore, the foam core material 4 fills the space surrounded by the first FRP skin material 2 and the second FRP skin material 3.

  Next, the molding process of the curved FRP sandwich structure 1 will be described. For forming the curved FRP sandwich structure 1, a convex mold 5 shown in FIG. 3 is used. FIG. 3 is a perspective view showing a convex mold 5 used for molding the curved FRP sandwich structure 1.

  As shown in FIG. 3, the convex mold 5 has a convex curved surface 5a having a desired mirror surface accuracy, and the convex curved surface 5a is directed vertically downward from the outer peripheral part of the convex curved surface 5a. And an extending side portion 5b. In this example, the convex mold 5 has a cylindrical shape whose one end surface is the convex curved surface portion 5a. Here, the side surface portion 5b refers only to the upper end portion of the cylindrical shape.

  The shape of the convex curved surface portion 5a may be a convex surface without a concave portion, and a spherical surface, a paraboloid of revolution rotated about a symmetry axis of a parabola as a rotation axis, a curved surface drawn on a plane as a plane A cylindrical surface translated in the vertical direction (however, the curve should be in the form of a convex cross over the entire surface), or a curved shape in which these surfaces are continuously connected is preferable. In the first embodiment, an example in which the shape of the convex curved surface portion 5a is a spherical surface will be described. Hereinafter, in the axial direction of the convex mold 5, the convex curved surface portion 5a side will be described as the upper side.

  First, the forming process of the first FRP skin material 2 will be described with reference to FIGS. 4 to 10. FIG. 4 is a cross-sectional view showing a state in which the first fiber cloth is laminated on the convex mold 5. FIG. 5 is a perspective view showing a state in which the first fiber cloth is in close contact with the convex mold 5. FIG. 6 is a perspective view showing a state in which the first fiber cloth is laminated on the convex mold 5.

  FIG. 7 is a cross-sectional view showing the peel ply and the flow media laminated on the first fiber cloth. FIG. 8 is a cross-sectional view showing a first forming apparatus for forming the first FRP skin material 2. Further, FIG. 9 is a cross-sectional view showing a state in which the liquid resin is injected into the first molding device under vacuum pressure. Furthermore, FIG. 10 is a cross-sectional view showing the first FRP surface material 2 from which all auxiliary materials have been removed after liquid resin curing.

<First skin material forming process>
As shown in FIG. 4, first, the entire convex curved surface portion 5a of the convex mold 5 and the side surface 5b of the convex mold 5 are subjected to a release treatment, and then at least one layer of the first fiber cloth 6a is formed. Stack. In the first embodiment, an example in which two layers of the first fiber cloth 6a are laminated is shown.

  The first fiber cloth 6a may be a woven fabric in which a fiber bundle in which fibers are bundled is woven in a two-dimensional plane, that is, a plane, and is not limited by the woven structure. Moreover, the raw material of the 1st fiber cloth 6a should just be a fibrous raw material, and is not limited by a material.

  Since the first fiber cloth 6 a is woven in a flat surface, when the first fiber cloth 6 a is laminated on the convex mold 5, only by placing the first fiber cloth 6 a on the convex mold 5, one of the first fiber cloth 6 a The department is too much to be jealous. If the first FRP skin material 2 is molded while the first fiber cloth 6a is wrinkled, the fibers may be bent at the wrinkles, and the desired mechanical properties, in this example, the mirror accuracy may not be obtained. . Therefore, it is necessary to bring the first fiber cloth 6 a into close contact with the convex mold 5.

  Therefore, in the first embodiment, in order to bring the first fiber cloth 6a into close contact with the convex mold 5, the fiber bundle of the first fiber cloth 6a serving as a reference is fixed to the convex mold 5, and this is used as a reference. The first fiber cloth 6a is deformed so that the remaining portion of the first fiber cloth 6a is spread outward and stretched to be in close contact with the convex mold 5. A specific example of the method of bringing the first fiber cloth 6a into close contact with the convex mold 5 will be described with reference to FIG.

  FIG. 5 exemplifies the case where the first fiber cloths 6a woven in two orthogonal axial directions are laminated. In order to bring the first fiber cloth 6a into close contact with the convex mold 5, first, an origin is set on the convex curved surface portion 5a. The origin is set in the axial direction of the convex mold 5 to the upper end of the side surface 5b, that is, the point of the convex curved surface 5a most distant from the outer circumferential surface of the convex curved surface 5a. In the first embodiment, since the shape of convex curved surface portion 5a is a spherical surface, the center of convex curved surface portion 5a, that is, the point where the axis of convex mold 5 and convex curved surface portion 5a intersect is the origin Do.

  Next, as shown by arrow A in FIG. 5, two reference axes are set along the radial direction of the convex mold 5 passing through the origin. In FIG. 5, two reference axes pass through the origin and are orthogonal to each other. In the first embodiment, since the shape of convex curved surface portion 5a is a spherical surface, if the two reference axes are axes passing the origin and along the radial direction of convex mold 5, at a desired position. Good.

  Next, as shown by the thick line B in FIG. 5, the two fiber bundles serving as the reference are temporarily fixed to the side surface 5 b of the convex mold 5 along the reference two axes. After the reference fiber bundle is fixed to the side surface 5b, as shown by arrow C in FIG. 5, the first fiber cloth 6a between the reference fiber bundles in the radial direction of the convex mold 5 is taken as a reference biaxial. It is closely attached to the convex mold 5 while extending and stretching in the middle direction of 45 °, that is, in the 45 ° direction.

  Finally, in a state of being in close contact with the convex mold 5, the excess first fiber cloth 6a protruding from the outer peripheral portion of the convex curved surface portion 5a shown by the dotted line in FIG. The fiber cloth 6 a is temporarily fixed to the side surface 5 b of the convex mold 5. That is, the first fiber cloth 6a is processed so that the height in the vertical direction is constant, and then temporarily fixed to the side surface 5b of the convex mold 5. The above procedure is repeated for the necessary number of layers, and the first fiber cloth 6a is laminated on the convex mold 5, as shown in FIG.

  Next, as shown in FIG. 7, the peel ply 7 and the flow media 8 are laminated in the order of the peel ply 7 and the flow media 8 on the first fiber cloth 6a. The peel ply 7 is an auxiliary material for peeling off the flow media 8 from the first FRP skin material 2 after resin curing, and allows the resin to pass but has releasability. The peel ply 7 is laminated so as to cover the entire first fiber cloth 6 a laminated to the convex mold 5.

  The flow media 8 is an auxiliary material for diffusing the resin in the inward direction of the convex curved surface portion 5 a and assisting the resin impregnation to the first fiber cloth 6 a. The flow media 8 is formed by hollowing out a central portion around the axis of the convex mold 5 and laminating. This is to prevent the resin from being sucked directly into the suction port 12 without impregnating the flow media 8 from the flow media 8 into the first fiber cloth 6a when the suction port 12 described later is provided in the central portion. .

  Also, the flow media 8 is laminated so as to cover the first fiber cloth 6 a and the peel ply 7. Further, the lower end portion of the flow media 8 stacked on the side surface portion 5 b is substantially at the same position as the lower end portion of the first fiber cloth 6 a in the axial direction of the convex mold 5 and above the lower end portion of the peel ply 7 positioned. That is, the flow media 8 covers the entire first fiber cloth 6a but does not cover the entire peel ply 7 covering the first fiber cloth 6a.

  Next, as shown in FIG. 8, the sealant 9 a is made one round along the circumferential direction of the convex mold 5 below the lower end of the peel ply 7 in the axial direction of the convex mold 5. Lay down. Moreover, the injection port 10 which resin can impregnate upwards is installed in at least one or more places of the circumferential direction of the sealant 9a.

  In the first embodiment, the case where the inlets 10 are installed at two locations facing each other in the radial direction is shown. The injection port 10 may be provided at one place or three or more places. In addition, the injection port 10 is installed along the circumferential direction of the side portion 5b of the convex mold 5 so that the resin is impregnated uniformly from the entire outer peripheral portion. good.

  Next, the bagging film 11 is overlaid so as to cover the portion where the first fiber cloth 6a, the peel ply 7, and the flow media 8 are laminated and the portion where the sealant 9a provided with the inlet 10 is laid. In the bagging film 11, a cut for inserting the suction port 12 is inserted at the same position as the central portion where the flow media 8 is cut out about the axis of the convex mold 5.

  After the suction port 12 is inserted into the cut of the bagging film 11, the suction port 12 and the bagging film 11 are sealed with the sealant 9b. The outer edge portion of the bagging film 11 is also sealed with a sealant 9a laid in advance, and the suction port 12 is connected to a vacuum pump, whereby a first molding apparatus for molding the first FRP surface material 2 can be made.

  After the first molding device is completed, the resin for injection (resin) 13 is injected from the injection port 10 in a state where the pressure in the inside is reduced by a vacuum pump connected to the suction port 12. The resin 13 for injection is not particularly limited as long as it is a material of low viscosity and is a thermosetting resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin, cyanate ester resin, etc. Vinyl ester resins are preferred.

  After filling the resin 13 for injection into the first fiber cloth 6a, the resin 13 for injection is cured under normal temperature or under heating conditions according to the type of the resin 13 for injection. After the injection resin 13 is completely cured, the auxiliary materials such as the sealants 9a and 9b, the suction port 12 and the bagging film 11 are removed, and the peel ply 7 and the flow media 8 are peeled off, as shown in FIG. FRP skin material 2 is obtained. Therefore, the first FRP skin material 2 is constituted by the first curved surface skin portion 2a molded on the convex curved surface portion 5a and the first rib portion 2b molded along the side surface portion 5b.

  When peeling off the peel ply 7 and the flow medium 8 from the first FRP surface material 2, part or all of the first FRP surface material 2 peels from the convex mold 5 because the mold release treatment is performed. It becomes. However, in the first FRP surface material 2, the rib portion 2 b is formed on the outer peripheral portion of the convex curved surface portion 5 a which is the upper portion of the side surface portion 5 b of the convex mold 5. As a result, the deformation of the first FRP surface material 2 due to the temperature difference and the cure shrinkage of the resin is suppressed. Therefore, the molding die side surface of the first curved surface skin portion 2a can be molded into a curved surface satisfying the same desired dimensional accuracy as the convex curved surface portion 5a.

  Next, the bonding process of the first FRP surface material 2 and the foamed core material 4 will be described with reference to FIGS. FIG. 11 is a cross-sectional view showing a state in which an adhesive resin is applied to the surface of the first curved surface skin portion 2a. Further, FIG. 12 is a cross-sectional view showing a state in which the foamed core material 4 coated with the adhesive resin on the concave side is installed on the first curved surface skin portion 2a. Further, FIG. 13 shows a state where the sealant is laid on the side surface 5b of the convex mold 5 and the suction port 12 is installed, the bagging film 11 is overlapped on the foam core 4 and the outer edge is sealed with the sealant. It is a sectional view showing. FIG. 14 is a cross-sectional view showing a state in which the auxiliary material is completely removed after the adhesive resin is cured.

  First, before carrying out the bonding step, the foam core material 4 is processed into a desired shape. Here, the desired shape has a concave curved surface 4a along the curved surface of the first curved surface skin portion 2a separated from the convex curved surface portion 5a in the axial direction of the convex mold 5 and has a desired thickness distribution It is a curved surface shape. The concave curved surface 4a of the foamed core material 4 may not be processed completely along the first curved surface skin portion 2a, and deforms and adheres to the first curved surface skin portion 2a when the atmospheric pressure is applied. Some degree of error is acceptable.

  The outer peripheral portion of the foam core material 4 reaches the rib portion 2 b. This is because, when the second fiber cloth 6b is laminated on the foamed core material 4 in the second skin material forming step described later, if there is a gap between the outer peripheral portion of the foamed core material 4 and the rib portion 2b, the foamed core It is difficult to bring the second fiber cloth 6b into intimate contact with the concave portion formed by the outer peripheral portion (or the upper surface portion) of the material 4 and the first curved surface skin portion 2a, and the second fiber cloth 6b is stretched against the concave portion There is a risk of

  If the second fiber cloth 6b is stretched, air bubbles may enter into the reentrant portion to cause molding defects, or resin lumps may be generated, and adverse effects such as failure to obtain a desired mirror surface accuracy due to curing shrinkage of the resin may be considered. As long as the outer peripheral portion of the foam core material 4 has reached the rib portion 2b, there is no reentrant portion, so that the second fiber cloth 6b is stretched and easily adhered to the foam core material 4 and the first FRP surface material 2 be able to.

  Although the processing method of the foaming core material 4 is not particularly limited, for example, thermal processing which bends the foaming core material 4 by heating and pressing, and machining which cuts by a machine tool are considered. When the thickness of the foam core material 4 is constant, it can be processed only by bending the flat foam core material, and thermal processing by heating and pressing is preferable. In the first embodiment, an example in which the thickness of the foamed core material 4 is constant will be described.

<Core material bonding process>
First, as shown in FIG. 11, the adhesive resin 14 is applied to the upper surface of the first curved surface skin portion 2a. The adhesive resin 14 is not particularly limited as long as it is a liquid resin at normal temperature. However, a vinyl ester resin curable at normal temperature is preferable, and a resin of the same kind as the injection resin 13 used for molding the first FRP skin material 2 is more preferable.

  Next, the adhesive resin 14 is applied also to the concave curved surface 4 a of the foamed core material 4, and as shown in FIG. 12, the concave curved surface 4 a of the foamed core material 4 coated with the adhesive resin 14 is the adhesive resin 14. The foamed core material 4 is placed on the first curved surface skin portion 2a so as to face the first curved surface skin portion 2a coated with the above. At this time, only by installing the foam core material 4, air bubbles are mixed in the adhesive resin 14 between the foam core material 4 and the first curved surface skin portion 2a, so the load is applied from the top of the foam core material 4. By adding, part of the air bubbles are discharged to the outside of the adhesive layer by the adhesive resin 14.

  In the first embodiment, the bonding resin 14 is applied to both the concave curved surface 4a and the first curved surface skin portion 2a, but may be applied to either one.

  Next, as shown in FIG. 13, the sealant 9 c is laid one round along the circumferential direction of the side surface portion 5 b of the convex mold 5. At this time, the sealant 9 c is laid below the lower end portion of the rib portion 2 b in the axial direction of the convex mold 5. In addition, the suction port 12 for sucking the air downward is installed at one or more places in the circumferential direction of the sealant 9c.

  The first embodiment exemplifies the case where the suction ports 12 are installed at two locations facing each other in the radial direction. In addition, one suction opening 12 may be provided, or three or more suction openings may be provided.

  Furthermore, the bagging film 11 is overlapped so as to cover the whole including the first FRP surface material 2 and the foam core material 4, and the outer edge portion of the bagging film 11 is sealed with the sealant 9 c laid in advance. Thereafter, a vacuum pump is connected to the suction port 12, and the inside is depressurized by suction with the vacuum pump. As a result, pressure is applied to the foamed core material 4 to discharge air bubbles and excess resin inside the adhesive resin 14.

  After the bubbles and the excess resin are completely discharged, the suction port 12 is closed, and the adhesive resin 14 is cured while maintaining the reduced pressure state. The adhesive resin 14 is cured at normal temperature or under heating conditions depending on the type of resin. After the adhesive resin 14 is completely cured, the auxiliary material such as the sealant 9c, the suction port 12 and the bagging film 11 is removed. Thereby, as shown in FIG. 14, the molded object with which the 1st FRP skin material 2 and the foaming core material 4 were adhere | attached is obtained.

  Next, the forming process of the second FRP skin material 3 will be described with reference to FIGS. In the molding process of the second FRP skin material 3, the convex mold 5 in a state in which the first FRP skin material 2 and the foamed core material 4 are provided is a molding die.

  FIG. 15 is a cross-sectional view showing a state in which the second fiber cloth is laminated so as to cover the foamed core material 4. FIG. 16 shows a second embodiment of the present invention, when the outer peripheral portion of the foam core material 4 does not reach the rib portion 2b, with respect to the concave corner portion formed by the outer peripheral portion (or upper surface portion) of the foam core member 4 and the first curved surface skin portion 2a. FIG. 7 is an enlarged view of a concave corner in a cross section showing a state in which the fiber cloth 6b is stretched. FIG. 17 is a cross-sectional view showing a state in which the peel ply 7 and the flow media 8 are laminated on the second fiber cloth. Furthermore, FIG. 18 is a cross-sectional view showing a second forming device for forming the second FRP skin material 3. FIG. 19 is a cross-sectional view showing a state in which the injection resin 13 is injected into the second molding apparatus under vacuum pressure. FIG. 20 is a cross-sectional view showing a state in which all the auxiliary materials are removed after the injection resin 13 is cured, and the molded body is released from the convex mold 5.

<Second skin material forming process>
First, as shown in FIG. 15, at least one second fiber cloth 6 b is laminated so as to cover the foamed core material 4 and the rib portion 2 b in the axial direction of the convex mold 5. The second fiber cloth 6 b is laminated while being spread and stretched along the convex curved surface 4 b of the foam core material 4. Here, the second fiber cloth 6b is the same as the first fiber cloth 6a used in the first skin material forming step.

  Here, when there is a gap between the outer peripheral portion of the foamed core material 4 and the rib portion 2b when the outer peripheral portion of the foamed core material 4 does not reach the rib portion 2b, the outer peripheral portion (or the upper surface portion) of the foamed core material 4 And the first curved surface skin portion 2a make it difficult to cause the second fiber cloth 6b to adhere closely, and as shown in FIG. 16, there is a fear that the tension 17 of the second fiber cloth 6b with respect to the concave portion is generated. There is.

  On the other hand, as shown in FIG. 15, if the outer peripheral portion of the foam core material 4 reaches the rib portion 2b, there is no concave portion. Therefore, the second fiber cloth 6b can be easily brought into close contact with the foamed core material 4 and the first FRP skin material 2 while being stretched.

  Next, as shown in FIG. 17, the peel ply 7 and the flow media 8 are laminated in the order of the peel ply 7 and the flow media 8 on the second fiber cloth 6 b. The flow media 8 is formed by hollowing out a central portion around the axis of the convex mold 5 and laminating.

  Next, as shown in FIG. 18, the sealant 9 a is laid one round along the circumferential direction of the side surface portion 5 b of the convex mold 5. At this time, the sealant 9 a is laid below the lower end portion of the peel ply 7 in the axial direction of the convex mold 5. Moreover, the injection port 10 which resin can impregnate upwards is installed in at least one or more places of the circumferential direction of the sealant 9a.

  Thereafter, the bagging film 11 is overlaid so as to cover the portion where the second fiber cloth 6b, the peel ply 7, and the flow media 8 are laminated and the portion where the sealant 9a provided with the inlet 10 is laid. In the bagging film 11, a cut for inserting the suction port 12 is inserted at the same position as the central portion where the flow media 8 is cut out about the axis of the convex mold 5.

After the suction port 12 is inserted into the cut of the bagging film 11, the suction port 12 and the bagging film 11 are sealed with the sealant 9b. The outer edge portion of the bagging film 11 is also sealed with a sealant 9a laid in advance, and the suction port 12 is connected to a vacuum pump, whereby a second molding device for molding the second FRP skin material 3 can be obtained.

  After the second molding apparatus is completed, the resin for injection 13 is injected from the injection port 10 in a state where the inside is depressurized by a vacuum pump connected to the suction port 12 as shown in FIG.

  After filling the injection resin 13 into the second fiber cloth 6b, the injection resin 13 is cured at normal temperature or under heating conditions according to the type of injection resin 13. After the resin 13 for injection is completely cured, the auxiliary materials such as the sealants 9a and 9b, the suction port 12 and the bagging film 11 are removed, and the peel ply 7 and the flow media 8 are peeled off to form burrs 15 as shown in FIG. To obtain a curved FRP sandwich structure 1 with.

  Here, the second FRP skin material 3 includes a second curved surface skin portion 3 a formed on the convex curved surface 4 b and a core side surface 4 c and a first rib which are end surfaces of the convex mold 5 of the foam core material 4. It is comprised by the 2nd rib part 3b shape | molded on the part 2b.

  At this time, in the axial direction of the convex mold 5, a portion where the first rib portion 2b and the second rib portion 3b are integrated protrudes downward below the first curved surface skin portion 2a. Hereinafter, this protruding portion is referred to as a burr 15.

  Finally, the removal process of the burrs 15 will be described with reference to FIG. FIG. 21 is a cross-sectional view showing the curved FRP sandwich structure 1 from which the burrs 15 have been removed.

<Protrusion removal process>
As shown in FIG. 21, the burr 15 is the first portion of the portion to which the first rib portion 2 b and the second rib portion 3 b shown in FIG. 20 are adhered in the axial direction of the convex mold 5. The concave surface of the curved surface skin portion 2a is a portion below the surface extended along the concave surface satisfying the desired mirror surface accuracy. Therefore, the burrs 15 are formed along the side surface portions 5 b of the convex mold 5 and extend in the axial direction of the convex mold 5.

  Therefore, the burrs 15 are cut out and removed along the concave surface satisfying the desired mirror surface accuracy of the first curved surface skin portion 2a which is the concave side of the curved FRP sandwich structure 1. The burr 15 is thin because the first rib portion 2 b and the second rib portion 3 b are integrated. Therefore, the burrs 15 can be removed manually by a simple processing method, for example, a grinder, without using a large-scale processing machine such as a three-dimensional processing machine.

  In the method of manufacturing the curved FRP sandwich structure according to the first embodiment, the convex curved surface portion having a desired mirror surface accuracy and the side surface portion extending vertically downward from the outer peripheral portion of the convex curved surface portion are included. Using a convex mold. Further, the method of manufacturing the curved FRP sandwich structure includes a first skin material forming step of forming a first FRP skin material having a first rib portion provided along the side surface portion.

  With such a configuration, when the injected resin for injection is cured, the first rib portion is caught on the side face of the convex mold, and the first FRP surface material is produced when the injected resin for injection is cured. Deformation can be suppressed. As a result, the first FRP surface material can obtain a desired mirror surface accuracy.

  Further, in the method of manufacturing the curved FRP sandwich structure, since the autoclave forming method is not used, the molding cost of the curved sandwich structure can be reduced.

  Furthermore, the method of manufacturing the curved FRP sandwich structure has a second skin material forming step of molding the second FRP skin material so as to cover the foam core material. Thereby, the process of adhere | attaching a protective plate to the edge part of the foaming core material which is not normally pinched | interposed into a skin material can be skipped. As a result, the molding time of the curved FRP sandwich structure can be shortened.

  Moreover, a 2nd rib part is shape | molded by the 2nd surface material formation process at the position which overlaps with a 1st rib part. Thereby, when the injected resin for injection is cured, the first rib portion and the second rib portion are caught on the side surface of the convex mold, and the entire curved FRP sandwich structure occurs when the injected resin for injection is cured. Deformation can be suppressed.

  Furthermore, since the burr formed by the first rib portion and the second rib portion is thin, it can be removed manually by the protrusion removing step.

  Further, in the step of laminating the first fiber cloth on the convex curved surface portion, two reference axes passing through the origin set on the convex curved surface portion are set, and the fiber bundle of the first fiber cloth is temporarily attached along the reference axis. After stopping, the first fiber cloth between the reference axes is spread and pulled to bring the first fiber cloth into close contact with the convex curved surface portion. At this time, the origin is set to the point of the convex curved surface portion most distant from the upper end portion of the side surface portion in the axial direction of the convex mold. This can prevent the first fiber cloth from being wrinkled on the convex curved surface portion. As a result, it is possible to prevent the deterioration of mechanical properties due to the generation of wrinkles.

Second Embodiment
In the first embodiment, an example in which the shape of the convex curved surface portion 5 a of the convex mold 5 is a spherical surface has been described. On the other hand, in the second embodiment, an example in which the shape of the convex curved surface portion 5a is a paraboloid of revolution will be described.

  FIG. 22 is a cross-sectional view of the convex mold 5 used in the second embodiment of the present invention on the plane of symmetry. FIG. 23 is a perspective view showing a curved FRP sandwich structure 1 molded using the convex mold 5 of FIG. The method of manufacturing the curved FRP sandwich structure 1 is the same as the method of manufacturing the first embodiment except that the shape of the convex curved portion 5a is different.

  The paraboloid of revolution, which has the shape of the convex curved surface portion 5a, is a curved surface expressed by the following equation (1). Here, a in the following equation (1) is an arbitrary positive number.

    z = a (x 2 + y 2) (1)

  Since all radio waves and electromagnetic waves entering from the z-axis direction pass through the focal point (x, y, z) = (0, 0, 1 (4a)), the paraboloid of revolution has the reflection curved surface shape of the antenna reflector Often used as

  FIG. 24 is a view showing a paraboloid for obtaining the convex curved surface portion 5 a of FIG. 23. As shown in FIG. 24, the paraboloid of revolution is a rotationally symmetric curved surface centered on the rotation axis D when cut off in a plane perpendicular to the z-axis, and the point farthest from the cutting plane is the cut curved surface It becomes the center. However, when cut off at other cut surfaces, the cut surface is not rotationally symmetrical, and the point farthest from the cut surface is offset from the center of the cut surface.

  As shown in FIGS. 22 and 23, in the second embodiment, the shape of the convex curved surface portion 5a is a paraboloid that is obliquely cut at the dotted line E with respect to the rotation axis D of FIG. There is. The paraboloid of revolution has one plane of symmetry, even when cut obliquely with respect to the axis of rotation. Also, the plane of symmetry includes the point farthest from the cutting plane and the major axis of the outer edge of the convex curved surface forming an ellipse. In FIG. 22, the point farthest from the cutting plane is shifted from the center to the right as indicated by a point F.

  When laminating the first fiber cloth 6a on the convex curved surface portion 5a having a shape of a paraboloid that is cut off obliquely with respect to the rotation axis, the point F is set as the origin. That is, in the axial direction of the convex mold 5, the origin is set to the point of the convex curved surface 5a which is most distant from the upper end of the side surface 5b, that is, the outer circumferential surface of the convex curved surface 5a.

  Further, the reference axis passes through the origin and sets a first axis parallel to the symmetry plane of the convex curved surface portion 5a and a second axis orthogonal to the first axis. In particular, when the convex curved surface portion 5a has an elliptical shape, the reference axis is preferably the major axis direction and the minor axis direction. Therefore, when the shape of the convex curved surface portion 5a is a paraboloid of revolution, the first axis is always a line parallel to the plane of symmetry of the convex curved surface portion 5a.

  The other configuration and manufacturing method are the same as in the first embodiment, and a curved FRP sandwich structure 1 as shown in FIG. 23 is obtained.

  In the method of manufacturing the curved FRP sandwich structure in the second embodiment, even if the curved FRP sandwich structure is formed using a convex mold in which the convex curved surface portion is a paraboloid of revolution. As in the first embodiment, the desired mirror surface accuracy can be obtained, and the molding cost of the curved sandwich structure can be reduced.

  In the first embodiment and the second embodiment, a spherical surface and a paraboloid of revolution are shown in the shape of the convex curved surface portion 5a, but all incident radio waves and electromagnetic waves can pass through the focal point. Any shape may be used, for example, an elliptical sphere.

Third Embodiment
In the first embodiment, an example in which the shape of the convex curved surface portion 5 a of the convex mold 5 is a spherical surface has been described. On the other hand, in the third embodiment, an example in which the shape of the convex curved surface portion 5a is a cylindrical surface will be described.

  FIG. 25 is a cross-sectional view of a convex mold 5 used in the third embodiment of the present invention in a plane perpendicular to the axial direction. FIG. 26 is a perspective view showing a curved FRP sandwich structure 1 molded using the convex mold 5 of FIG. The method of manufacturing the curved FRP sandwich structure 1 in the third embodiment is the same as the manufacturing method of the first embodiment except that the shape of the convex curved surface portion 5a is different.

  A cylindrical surface having the shape of the convex curved surface portion 5a is a curved surface represented by the following expression (2). In addition, f (x) of the following Formula (2) is an arbitrary function about x defined in the range of arbitrary x.

    y = f (x) (constant regardless of z) (2)

  f (x) must be convex over the entire definition range, and when the y-axis direction is vertically upward, the second derivative of f (x) for x extends over the entire definition range It must be negative.

  By making the function form of f (x) streamline, it is possible to reduce the aerodynamic drag of the moving body.

  The midpoint between the x-axis direction and the z-axis direction on the cylindrical surface is taken as the origin. The reference axis passes through the origin and sets a first axis parallel to the z-axis and a second axis parallel to the x-axis.

  The other configuration and manufacturing method are the same as in the first embodiment, and a curved FRP sandwich structure 1 as shown in FIG. 26 is obtained.

  In the method of manufacturing a curved FRP sandwich structure according to the third embodiment, even if the curved FRP sandwich structure is formed using a convex mold having a convex curved surface portion as a cylindrical surface, Similar to the first embodiment, the desired shape accuracy can be obtained, and the molding cost of the curved sandwich structure can be reduced.

  DESCRIPTION OF SYMBOLS 1 Curved-surface-like FRP sandwich structure (curved-surface-like sandwich structure), 2 1st FRP skin material (1st skin material), 2a 1st curved surface skin part, 2b 1st rib part, 3 2nd FRP skin material (2nd skin material), 3a second curved surface skin portion, 3b second rib portion, 4 foam core material, 5 convex mold, 5a convex curved surface portion, 5b side surface portion, 6a first fiber cloth, 6b first 2 Fiber cloth, 13 injection resin (resin), 15 burrs, 17 second fiber cloth 6b.

Claims (5)

Using a convex mold having a convex curved surface portion having a desired mirror surface accuracy and a side surface portion extending downward from an outer peripheral portion of the convex curved surface portion when the convex curved surface portion is directed vertically upward, A method for producing a curved sandwich structure, which is integrally molded by covering the periphery of a foam core material with a fiber reinforced plastic skin material,
When laminating the first fiber cloth on the convex mold, the end of the first fiber cloth is fixed to the side surface to expand the first fiber cloth on the convex curved surface portion. After the previous step of bringing into close contact with each other, a resin is impregnated in the first fiber cloth and cured to form a first curved surface skin portion molded on the convex curved surface portion and a first molding formed on the side surface portion A first skin material molding step of molding a first skin material having a rib portion;
The foam core material previously processed into a curved surface shape along the upper surface shape of the first curved surface skin portion molded on the convex curved surface portion and having an outer peripheral portion reaching the first rib portion, A core material bonding step of bonding on the first curved surface skin portion;
When laminating the second fiber cloth so as to cover the upper surface portion and the outer peripheral portion corresponding to the surface excluding the surface in contact with the first curved surface skin portion in the foamed core material, an end portion of the second fiber cloth By fixing the second fiber cloth to the upper surface portion and the outer peripheral portion of the foamed core material by fixing the first fiber portion to the first rib portion, and then impregnating the resin in the second fiber cloth A second curved surface skin portion molded on the upper surface portion of the foam core material, and a second rib portion molded over the first rib portion from the outer peripheral portion of the foam core material; A second surface material forming step of forming a second surface material having a second surface portion, and a portion formed by laminating the first rib portion and the second rib portion in the side surface portion of the convex mold. And projecting vertically downward of the first curved surface skin portion And a protrusion removing step of removing the second portion along the curved surface in contact with the convex curved surface portion in the first curved surface skin portion. The method for manufacturing a curved sandwich structure according to claim 1, wherein the outer peripheral portion of the foam core material is an outer peripheral surface having a width. The method for producing a curved sandwich structure according to claim 2, wherein the thickness of the foamed core material is constant over the entire surface. When the convex curved surface portion is a spherical surface, the front step in the first skin material forming step is
The center of the spherical surface is set as the origin, and two reference axes orthogonal to each other along the radial direction of the spherical surface through the origin are set, and two of the first fiber crosses along the respective two reference axes Temporarily fixing the fiber bundle of the book to the side portion;
Expanding the first fiber cloth between the two fiber bundles toward the middle direction between the two fiber bundles and bringing the first fiber cloth into close contact with the convex curved surface portion; And after the step of bringing into close contact, after cutting off the excess portion of the first fiber cloth so that the height in the vertical direction of the first fiber cloth in the first rib portion becomes constant, the first fiber The method for producing a curved sandwich structure according to any one of claims 1 to 3, further comprising the step of temporarily fixing a cloth to the side surface portion. In the case where the convex curved surface portion is a paraboloid cut off obliquely with respect to the rotation axis, the pre-process in the first skin material forming process is:
For vertically upward, the point of the convex curved surface section farthest from the outer peripheral section is set as the origin, and the first axis parallel to the symmetry plane of the paraboloid of revolution passes through the origin and the first axis Setting two orthogonal axes as the two reference axes, and temporarily fixing the two fiber bundles of the first fiber cloth along the two reference axes to the convex curved surface portion;
Expanding the first fiber cloth between the two fiber bundles toward the middle direction between the two fiber bundles and bringing the first fiber cloth into close contact with the convex curved surface portion; And after the step of bringing into close contact, after cutting off the excess portion of the first fiber cloth so that the height in the vertical direction of the first fiber cloth in the first rib portion becomes constant, the first fiber The method for producing a curved sandwich structure according to any one of claims 1 to 3, further comprising the step of temporarily fixing a cloth to the side surface portion.

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