JP3723659B2 - Method for forming honeycomb core material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a honeycomb core material, in which a core material is formed by forming a prepreg into a wave shape (unevenness).
[0002]
[Prior art]
In recent years, due to demands for weight reduction and higher strength, the development of prepregs with a thermosetting resin such as epoxy resin and unsaturated polyester as a matrix and addition of reinforcing materials such as carbon fiber, aramid fiber or glass fiber has been remarkable. The need for various products using prepreg has been greatly increased.
[0003]
In addition to this, recently, there is an increasing need for composite products using a thermoplastic resin matrix such as nylon or polyetheretherketone (PEEK).
[0004]
In particular, this type of prepreg is a material with excellent properties that can produce lightweight, high-strength structural products. Therefore, composite materials exert great power as various members used in extreme conditions such as the aerospace field. I think that.
[0005]
When a thermosetting resin or thermoplastic resin is used as a matrix as a core of a honeycomb structure used in a composite structure, and a long fiber carbon fiber reinforced plastic (CFRP) is used as a reinforcing fiber, a trapezoidal uneven mold is conventionally used. It was necessary to laminate a prepreg on the substrate and cure it with an autoclave or a press.
[0006]
[Problems to be solved by the invention]
However, it is known that if a long fiber carbon fiber reinforced plastic (CFRP) is used as a reinforcing fiber, a honeycomb plate having high strength and rigidity can be formed. There has been a problem that it takes time to prepare or laminate the mold.
[0007]
The present invention has been made paying attention to the above circumstances, and the object of the present invention is for a honeycomb core that can easily form a honeycomb core material having an arbitrary shape even for a prepreg containing highly rigid fibers. The object is to provide a method of forming a material.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there is provided a pair of bowl-shaped forming jigs in which both end portions in the longitudinal direction of a plurality of square bar members are rotatably connected by a connecting member. A sandwich structure is formed by sandwiching a prepreg impregnated with a thermosetting resin or a thermoplastic resin as a matrix between sheets of reinforcing fibers, and this sandwich structure is heated and pressed by a press die together with the molding jig. Thereafter, the prepreg is cured, and a honeycomb core material is formed following the shape of the forming jig.
[0009]
According to a second aspect of the present invention, in the molding jig according to the first aspect, first members and second members having different cross-sectional shapes are alternately arranged in parallel, and both end portions in the longitudinal direction are rotated by a connecting member. It is characterized by being connected freely.
A third aspect of the present invention is characterized in that the prepreg of the first aspect is a carbon fiber reinforced plastic.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a first embodiment. FIG. 1 shows a forming jig 1, which is formed in a bowl shape by a plurality of square bar members 2 and a connecting member 3 that connects both ends in the longitudinal direction of the square bar members 2. ing. That is, in the square bar member 2, for example, flat plate-like first members 2 a having a rectangular cross section and second members 2 b having a triangular cross section are alternately arranged in parallel.
[0011]
The first member 2a and the second member 2b are made of a metal or ceramic material having the same width and the same length. The connecting member 3 has a thin plate shape, one end of which is pivotally connected to the end surface of the first member 2 a by a pivot pin 4, and the other end of the second member 2 b by a pivot pin 4. It is rotatably connected to the end face.
[0012]
Therefore, the forming jig 1 can be folded and wound because the connecting member 3 is rotatable about the pivot pin 4 as a fulcrum. A plurality of the forming jigs 1 configured in this way are prepared, and two forming jigs 1 can be overlapped and joined together. The end surfaces of the first member 2a and the second member 2b An engagement hole 6 is provided in which both ends of the U-shaped coupling member 5 are engaged.
[0013]
Also, 7 shown in FIG. 2 is a prepreg used as a honeycomb core material, in which a thermoplastic resin is formed as a matrix on a base fabric made of reinforcing fibers such as carbon fibers, aramid fibers, glass fibers, and carbon fibers as a sheet. Either a flat plate, a thermoplastic resin woven into a base fabric, or a semi-cured material impregnated with a thermosetting resin as a matrix. The prepreg 7 is sandwiched between the two forming jigs 1 to form a sandwich. Then, as shown in FIG. 1, in a state where the first member 2a and the second member 2b of the two forming jigs 1 are opposed to each other, both ends of the connecting member 5 are connected to the first member 2a and The two forming jigs 1 are joined by engaging with the engaging holes 6 of the second member 2b.
[0014]
FIG. 3 shows a press die 8, which is composed of an upper press die 9 and a lower press die 10. The press upper mold 9 and the press lower mold 10 are provided with recesses 11 having a triangular cross section and trapezoidal protrusions 12 alternately and continuously, and the recesses 11 are substantially the same as the angle at the top of the second member 2b. It is formed in the same way, and the top part of the convex part 12 is formed in the substantially same width as the 1st member 2a. The press upper die 9 and the press lower die 10 are installed so that the concave portion 11 and the convex portion 12 face each other, the press upper die 9 is formed as a movable die, and the press lower die 10 is formed as a fixed die.
[0015]
Next, a method for forming the honeycomb core material will be described.
A flat prepreg 7 is sandwiched between two molding jigs 1 to form a sandwich. At this time, in a state where the first member 2a and the second member 2b of the two forming jigs 1 are opposed to each other, both ends of the coupling member 5 are connected to the first member 2a and the second member 2b. The sandwiched structure 13 is formed by engaging the engagement holes 6 and joining the two forming jigs 1 together.
[0016]
Next, the sandwich structure 13 is inserted between the upper press die 9 and the lower press die 10 of the press die 8. Then, when the first member 2a of the forming jig 1 located on the lower side of the sandwich structure 13 is positioned on the convex portion 12 of the press lower mold 10 and the second member 2b is positioned on the concave portion 11 of the press lower mold 10, Since the first member 2 a and the second member 2 b are rotatably connected by the connecting member 3, the first member 2 a is placed on the convex portion 12, and the second member 2 b is the concave portion 11. It falls into the inside and the sandwich structure 13 is bent into a wave shape. Then, the first member 2a of the forming jig 1 positioned above the sandwich structure 13 is opposed to the convex portion 12 of the upper press mold 9, and the second member 2b is opposed to the concave portion 11 of the upper press mold 9.
[0017]
In this state, the sandwich structure 13 is heated and the press upper die 9 is lowered to press the sandwich structure 13 between the press lower die 10 and the sandwich structure 13 is pressed between the press upper die 9 and the press lower die 10. Molded according to the shape of the mold 10. Here, in the case of a thermoplastic resin, the sandwich structure 13 is cooled to cure the prepreg 7, and in the case of a thermosetting resin, the reaction is accelerated and cured at a high temperature.
[0018]
Next, when the cured sandwich structure 13 is removed from the press die 8 and the coupling member 5 is removed, the prepreg 7 is separated from the two molding jigs 1 and, as shown in FIG. The honeycomb core material 14 formed alternately with 14b is formed.
[0019]
5 and 6 show a second embodiment. As shown in FIG. 5, the forming jig 15 of the present embodiment is formed in a bowl shape by a plurality of square bar members 16 and a connecting member 17 that connects both ends of the square bar members 16 in the longitudinal direction. Has been. That is, in the square bar member 16, the first member 16 a having a large trapezoidal cross section and the second member 16 b having a small trapezoidal cross section are alternately arranged in parallel. The trapezoidal inclination angle of the first member 16a and the trapezoidal inclination angle of the second member 16b are formed at the same angle, and one is provided when the second member 16b is placed on the first member 16a. A trapezoid is formed.
[0020]
The 1st member 16a and the 2nd member 16b are formed with the metal or ceramic material formed in the same length. The connecting member 17 has a thin plate shape, one end of which is pivotally connected to the end surface of the first member 16a by a pivot pin 19, and the other end of the second member 16b by a pivot pin 19. It is rotatably connected to the end face.
[0021]
Accordingly, the forming jig 15 can be folded and wound because the connecting member 17 is rotatable about the pivot pin 19 as a fulcrum. A plurality of the forming jigs 15 configured as described above are prepared, and two forming jigs 15 can be overlapped and joined. The end faces of the first member 16a and the second member 16b An engagement hole 21 is provided in which both ends of the U-shaped coupling member 20 are engaged.
[0022]
FIG. 6 shows a press die 22, which is composed of an upper press die 23 and a lower press die 24. The press upper mold 23 and the press lower mold 24 have press surfaces formed on flat surfaces 23a and 24a, the press upper mold 23 is formed as a movable mold, and the press lower mold 24 is formed as a fixed mold.
[0023]
Next, a method for forming the honeycomb core material will be described.
The flat prepreg 7 is sandwiched between two molding jigs 15 to form a sandwich. At this time, in a state where the first member 16a and the second member 16b of the two forming jigs 15 are opposed to each other, both ends of the coupling member 20 are connected to the first member 16a and the second member 16b. When the engaging structure 21 is engaged and the two forming jigs 15 are joined to form the sandwich structure 25, the first member 16a and the second member 16b are rotatably connected by the connecting member 18. Therefore, the sandwich structure 2 is bent in a wave shape by the first member 16a and the second member 16b.
[0024]
Next, the sandwich structure 25 is inserted between the upper press mold 23 and the lower press mold 24 of the press mold 22, and the sandwich structure 25 is placed on the flat surface 24 a of the lower press mold 24. In this state, when the sandwich structure 25 is heated and the press upper die 22 is lowered and the sandwich structure 25 is press-molded between the press lower die 23, the sandwich structure 25 has the first member 16a and the first member 16a. The second member 16b is shaped to follow the shape. Then, after the sandwich structure 25 is cooled and the prepreg 7 is cured, the sandwich structure 25 is removed from the press die 22 and the coupling member 22 is removed. Then, the prepreg 7 is separated from the two molding jigs 15, and the honeycomb structure 25 is removed. A core material is formed.
[0025]
In each of the above embodiments, a flat plate shape, a triangular shape, or a trapezoidal prismatic rod member is combined into a bowl shape as a forming jig, but the shape of the member is not limited to the above embodiment, It can be changed as appropriate.
[0026]
In addition, a base fabric was used as a sheet made of reinforcing fibers, and a prepreg was formed on the base fabric using a thermoplastic resin as a matrix. However, a prepreg may be formed using a thermoplastic resin as a matrix on a tape in which reinforcing fibers are aligned. Good.
[0027]
【The invention's effect】
As described above, according to the present invention, a prepreg impregnated with a thermosetting resin or a thermoplastic resin as a matrix is sandwiched between sheets of reinforcing fibers between two ridge-shaped forming jigs, and the prepreg is molded. After heating and pressurizing with a press die together with the tool, the prepreg is cured, and the honeycomb core material is molded according to the shape of the forming jig. The mold can be easily formed into a desired wave shape (unevenness), and the efficiency of the forming operation of the honeycomb core material can be improved.
[Brief description of the drawings]
1A and 1B show a forming jig for forming a honeycomb core material according to a first embodiment of the present invention, wherein FIG. 1A is a perspective view, FIG. 1B is a cross-sectional view taken along line AA, and FIG. The perspective view which expanded the B section.
FIG. 2 is a side view of a sandwich structure of two forming jigs and a prepreg according to the embodiment.
FIG. 3 is a longitudinal side view showing a state in which the sandwich structure is pressed by the press die according to the embodiment.
Fig. 4 is a perspective view of a honeycomb core material obtained by the same embodiment.
5A and 5B show a forming jig for forming a honeycomb core material according to a second embodiment of the present invention, wherein FIG. 5A is a perspective view, FIG. 5B is a cross-sectional view taken along the line CC, and FIG. The perspective view which expanded D section.
FIG. 6 is a longitudinal side view showing a state in which the sandwich structure is pressed by the press die according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Molding jig 2a ... 1st member 2b ... 2nd member 7 ... Prepreg 8 ... Press die

Claims (3)

A thermosetting resin or a thermoplastic resin is formed on a sheet made of reinforcing fibers between two hook-shaped forming jigs in which both ends in the longitudinal direction of a plurality of square bar members are rotatably connected by a connecting member. A sandwich structure is formed by sandwiching a prepreg impregnated as a matrix, and the sandwich structure is heated and pressed by a press die together with the molding jig, and then the prepreg is cured to follow the shape of the molding jig. A method for forming a honeycomb core material, comprising forming the honeycomb core material. The forming jig is characterized in that first members and second members having different cross-sectional shapes are alternately arranged in a parallel state, and both ends in the longitudinal direction thereof are rotatably connected by a connecting member. The method for forming a honeycomb core material according to claim 1. The method for molding a honeycomb core material according to claim 1, wherein the prepreg is a carbon fiber reinforced plastic.

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