JPH0698704B2 - Method for manufacturing CFRP joint - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a CFRP joint used for a joint between primary structural members of a frame structure.

Conventional technology CFRP (carbon fiber reinforced plastic) is expected to be a promising material in the field of aerospace because it has high mechanical properties such as specific strength and specific rigidity, and also has excellent thermal dimensional stability. ing. In addition, not only primary structural members for frame structures (truss or rigid frame type) used in outer space but also joints used for connecting the primary structures have been tried to be CFRP.

In this case, the primary structural member has a simple shape such as a pipe shape or a flat plate shape, whereas the joint has to be combined with a plurality of members, so the shape must be extremely complicated. . for that reason,
In molding the joint as described above, a molding method in which a chopped strand of carbon fiber is contained in a predetermined resin and a lamination molding method in which carbon fiber cloth is laminated are proposed (for example, 32nd International SAMPE S
ymposium papers April 6-9, 1987 P.772 to P.781).

Problems to be Solved by the Invention The molding method using the chopped strands of carbon fiber as described above has good manufacturability, but since the fibers are not continuous, the original strength and elasticity of the fibers cannot be fully utilized. ,
In addition to low mechanical properties as a molded product, it is difficult to achieve arbitrary specific strength and specific rigidity depending on the shape of the molded product.

In addition, in the lamination molding method, the more complicated the product shape, the more difficult it is to adapt the load-loading direction and the fiber direction. I have no choice. As a result, similar to the above, the original strength of the fiber cannot be fully utilized and a sufficient strength cannot be obtained as a product.

The present invention provides a method for producing a molded article having excellent mechanical properties by utilizing the original strength of the fiber.

Means for Solving the Problems The present invention is to manufacture a polyhedral polygonal CFRP joint used for a joint portion of a frame structure. First, a rectangular tubular CF preformed by a filament winding method is used.
The RP base material is cut to produce an angle-shaped primary molded product. In this case, the direction of the fibers in the base material is arbitrarily set according to the strength and rigidity required at the time of being configured as a joint.

Next, the plurality of angle-shaped primary molded products formed as described above are assembled to the outer periphery of the mandrel having a similar shape to the joint shape, and an intermediate assembly having a schematic shape of the joint is formed only by these primary molded products. Constitute. Here, a plurality of angle-shaped primary molded products are used as elements of the intermediate assembly, and when the final product, a polygonal prismatic joint, is developed, it can be developed into a combination of a plurality of angle-shaped blocks. This is because.

Then, carbon fiber is wound around the outer periphery of the above-mentioned intermediate assembly by a predetermined thickness by a filament winding method to form a secondary molding layer, and thereby a secondary molding layer is molded. Then, by removing the mandrel from the molded product, a joint which is a final product is obtained.

Examples FIGS. 1 and 2 show CF molded by the method of the present invention.
An example of an RP joint is shown. This joint 1
As is clear from the figure, since it has a polygonal square tube shape having six square tube portions 2, it is assumed that it is developed (however, here, for the sake of convenience, there is no secondary molding layer 4). It can be understood that the joint 1 is a combination of twelve angle-shaped blocks or primary moldings 3 (see FIG. 6). Therefore, in this embodiment, the joint 1 is constructed by using the above-mentioned primary molded product 3 as a basic element.

First, as shown in FIGS. 3 and 4, a base material 5 having a rectangular hollow cross-section structure is formed by a filament winding method mainly composed of carbon fiber, and the base material 5 is cut line.
A plurality of angle-shaped primary molded products 3 are obtained by cutting from C ₁ and C ₂ . As is well known, the base material 5 is formed by winding carbon fibers impregnated with resin around the outer periphery of a predetermined mandrel, and the direction of the fiber is, for example, symbol a in FIG. 5 (A). Alternatively, the primary molded product 3 may be formed along the longitudinal direction thereof, or may be formed in a so-called angle ply shape as shown by a symbol b in FIG. The direction of this fiber is arbitrarily set according to the strength, rigidity, etc. required when the joint 1 is constructed.

Next, as shown in FIG. 6, a total of 12 pieces (however, in FIG.
The primary moldings 3 (only one of which is shown) are assembled and temporarily fixed, and only the plurality of primary moldings 3 constitute an intermediate assembly 13 having a similar shape to the joint 1. As the mandrel 6 used here, it is necessary to pull it out of the molded product after the completion of molding, and therefore, for example, a disassembled type is used as shown in FIG.

That is, while the side blocks 9 are fixed to the core block 8 serving as the center on the four outer peripheral surfaces with bolts 10, the puller bolt holes 12 are formed in advance in each side block 9 separately from the bolt holes 11. deep. In removing the mandrel 6, the bolts 10 are removed, and then a puller bolt (not shown) is screwed into the puller bolt hole 12 so that the side block 9 is gradually removed from the core block 8. Thus 4 side blocks 9
Finally, the core block 8 can be removed by removing.

Then, carbon fibers are wound around the outer periphery of the intermediate assembly 13 configured as shown in FIG. 6 by the filament winding method to form the secondary molding layer 4 having a predetermined thickness as shown in FIGS. 1 and 2. To get the product shape. In this case, in order to wind up the primary molded article 3 which is a constituent element of each of the six square tube portions 2, the carbon fiber is wound as shown by an arrow e in FIG. 2 to form the secondary molded layer 4. .

Then, after waiting for the secondary molding layer 4 to harden, the mandrel 6 is disassembled and withdrawn in the same manner as described above, while finishing processing is performed to obtain the joint 1 of FIG. 1 which is the final product.

FIG. 8 shows another example of the joint formed by the method of the present invention. In contrast to the joint 1 shown in FIG. 1 having six square tube portions 2, the joint 21 shown in FIG. It is provided with five square tube portions 22, and in the case of this embodiment, a total of nine primary molded products 23 are formed as a base under the same manufacturing method as described above.

Then, the joints 1,21 shown in FIG. 1 and FIG.
Also in this case, for example, as shown in FIG. 9, it is connected to the primary structural member 14 of the frame structure by means of adhesion or bolts 15 or the like.

As described above, in the manufacturing method of the present invention, a plurality of angle-shaped primary molded products are combined to form an intermediate assembly, and carbon fibers are wound around the outer periphery by the filament winding method to form the intermediate assembly. Therefore, compared to the conventional molding method and lamination molding method, the direction of the fiber can be arbitrarily adapted to the load direction, and the strength of the fiber is fully utilized to make a joint with excellent mechanical properties. Can be obtained.

Further, in the present invention, since the filament winding method is consistently used as a basis, it is possible to reduce the processing time and cost, and since the fiber is cured in a tensioned state, it has high strength and high quality. A stable product is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a joint formed by the method of the present invention, FIG. 2 is a view in the P direction of FIG. 1, and FIG.
FIG. 4 is a perspective view of a base material used in the method of the present invention, FIG. 4 is a cross-sectional view of FIG. 3, and FIGS. 5 (A) and 5 (B) are perspective views for explaining the fiber direction of the primary molded product. FIG. 6 is a perspective view showing a relationship between a mandrel and a primary molded product when forming an intermediate assembly, FIG. 7 is a cross-sectional explanatory view of a main part of the mandrel of FIG. 6, and FIG. FIG. 9 is a perspective view showing another example of the joint to be molded, and FIG. 9 is a perspective view of an essential part showing a usage form of the joint shown in FIGS. 1 and 8. 1,21 ...... Joint, 2,22 …… Square tube part, 3,23 …… Primary molded product, 4 …… Secondary molding layer, 5 …… Base material, 6 …… Mandrel, 13 …… Intermediate assembly .

Claims (1)

[Claims] 1. A method for manufacturing a polyhedral polygonal CFRP joint for use in a joint portion of a frame structure, comprising a polygonal tubular tube preformed by a filament winding method.
The process of cutting the CFRP base material to make an angle-shaped primary molded product, the process of assembling multiple primary molded products on the outer periphery of the mandrel that is similar to the joint shape to form an intermediate assembly, and the intermediate assembly And a step of forming a secondary molding layer by winding a carbon fiber around the outer periphery of the solid body by a filament winding method to mold it into a joint shape.