JP3595213B2 - Method of forming FRP tube - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for forming a fiber-reinforced plastic (FRP) tube.
[0002]
[Prior art]
A support member of a deployment antenna of an artificial satellite used in space, for example, or a FRP tube used for a consumer tool such as a fishing rod is formed as shown in FIG.
That is, a mandrel 1 which is a metal round bar is laminated with an FRP prepreg (a fiber impregnated with a thermosetting resin) so that the fiber direction is in a predetermined direction, and a release film 3 is fixed on the outer periphery thereof. And a predetermined tension. Then, the FRP prepreg 2 is cured by heating and pressurizing in an autoclave apparatus with a vacuum bag, and a tube is formed. Thereafter, the release film 3 is peeled off, and the mandrel 1 is pulled out to form an FRP tube.
[0003]
As described above, conventionally, since the FRP prepreg 2 is hardened by wrapping the release film 3 and heating and pressurizing the FRP prepreg 2 in an autoclave device, the winding marks of the release film 3 (the pitch of the tape when winding the tape) are formed on the outer surface of the tube. Gap) remains. For this reason, in the related art, the step of the winding trace of the release film 3 is shaved by post-processing to smooth the surface, or the appearance is adjusted by further painting.
[0004]
[Problems to be solved by the invention]
However, the conventional FRP tube molding method has the following problems.
That is, since the FRP prepreg 2 is cured and formed by winding the release film 3 and applying heat and pressure, the winding marks of the release film 3 remain on the outer peripheral surface of the tube as described above, and the quality of the appearance is poor. It was necessary to perform a process of cutting the step of the winding trace by post-processing to smooth the surface.
[0005]
Further, in the step of cutting the step of the tape winding trace, it is necessary to make the entire tube uniform, but the presence of this step means that defects such as scratches may occur. In particular, when the tube is used in a place where the environment is severe, such as outer space, even a slight scratch may cause a problem.
[0006]
In addition, in the conventional method of forming an FRP tube, it is necessary to perform heating and pressurization in an autoclave apparatus as described above, so that many steps are required before the FRP tube is put into the autoclave apparatus.
[0007]
Further, since the material such as the release film 3 used in the conventional FRP tube molding method can be used only once, it is necessary according to the amount of the FRP tube to be produced.
[0008]
In the conventional method of forming an FRP tube, when a thick tube is formed, a prepreg corresponding to the thickness of the tube is laminated on the mandrel 1, and the release film 3 is applied to the FRP prepreg 2. It must be wound. However, when the release film 3 is wound around the thick FRP prepreg 2, twisting is likely to occur, and it becomes more difficult to form a uniform tube as the thickness increases.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a method of forming an FRP tube that has good appearance quality after tube formation and requires few forming steps.
[0010]
[Means for Solving the Problems]
The present invention fills a material having a higher expansion coefficient than metal between the pipe and the hollow layer so that a hollow layer is provided at a central portion in the cylindrical pipe, and fills the FRP prepreg in the hollow layer. Insert the metal mandrel laid up, apply heat to the curing temperature of the FRP prepreg, expand the material to fill the cavity layer, press-mold the FRP prepreg, and cool after completion of pressurization. The metal mandrel is pulled out by providing a cavity layer by shrinking the material.
[0011]
According to such a method, the FRP prepreg laid up on the mandrel is applied with a uniform pressure as a whole by the expansion of a material having a high expansion coefficient in the hollow layer provided at the center of the cylindrical pipe. It is pressed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a process of forming an FRP tube by a method of forming an FRP tube in the present embodiment, and FIG. 2 is a flowchart for explaining steps of a method of forming an FRP tube.
[0013]
In the method of forming an FRP tube according to the present embodiment, the hollow metal layer 10 having a length corresponding to the FRP tube to be formed is provided with a cavity layer 14 at the center thereof so that the expansion rate is higher than that of metal. A high material, for example, resin 12 is filled (see FIG. 1A). For example, a cylindrical member having a thickness corresponding to the cavity layer 14 is inserted into the center of the metal pipe 10, and the resin 12 is filled between the outer periphery of the member and the metal pipe 10. It can be formed by extracting the member.
[0014]
On the other hand, the metal mandrel 16 is coated with a release agent after the FRP tube is formed so that the metal mandrel 16 can be easily removed from the formed tube (FIG. 2, step A1). It is hardened (step A2).
[0015]
Next, an FRP prepreg 18 (a fiber impregnated with a thermosetting resin) is laminated on the metal mandrel 16 coated with the release agent such that the fiber direction is a predetermined direction (step A3). .
The steps A1 to A3 are almost the same as the steps in the conventional FRP tube molding method.
[0016]
Next, the metal mandrel 16 provided with the FRP prepreg 18 is inserted into the cavity layer 14 formed by the resin 12 in the metal pipe 10 described above as shown in FIG. 1A (step A4). ). Then, the entire configuration shown in FIG. 1A is heated to the curing temperature of the resin impregnated with the FRP prepreg 18 (step A5).
[0017]
As a result, the resin 12 has a higher expansion coefficient than the metal, so that it expands greatly and fills the cavity layer 14 as shown in FIG. 1B. Therefore, the FRP prepreg 18 laminated on the metal mandrel 16 is pressed by the expansion of the resin 12. At this time, since the metal pipe 10 has a cylindrical shape, when the resin 12 filled in the metal pipe 10 expands due to heating, it is necessary to uniformly press the entire outer peripheral portion against the FRP prepreg 18. Become. Thus, the tube is formed by pressurizing the FRP prepreg 18 by the expansion of the resin 12.
[0018]
When the pressurization of the FRP prepreg 18 is completed, the resin 12 contracts due to cooling and returns to the state where the cavity layer 14 exists as shown in FIG. 1A, so that the tube is formed on the outer peripheral portion. The metal mandrel 16 is removed from the cavity layer 14 (Step A6). Further, by pulling out the metal mandrel 16 from the tube, the forming of the FRP tube is completed (Step A7).
[0019]
In this manner, in the method of forming an FRP tube according to the present embodiment, since there is no step of winding the release film around the outer peripheral portion of the FRP prepreg 18, the outer circumference of the tube formed by winding the release film as in the related art is used. The step is eliminated, and the quality of the appearance is improved. For this reason, a post-process of polishing the outer periphery of the tube after forming the FRP tube is not required, and the number of processes can be reduced, and generation of scratches due to the polishing operation can be avoided. In addition, since there is no step at the outer periphery of the tube and the tube is uniform, the stress distribution on the tube is also uniform, so that a durable quality can be obtained even in a severe environment such as outer space.
[0020]
Further, since the resin 12 is a silicone resin, the molded tube and the resin 12 can be separated from each other without performing a release treatment such as winding a release film around the outer periphery of the FRP prepreg 18, thereby reducing the number of steps. be able to.
[0021]
Further, since the resin 12 has heat resistance, the resin 12 is heated and expanded for forming the tube, and then cooled to return to a state before the tube is formed, and can be used again for forming the tube. Therefore, it is not necessary to replace the resin 12 every time the tube is formed, so that the operation of filling the resin 12 so that the hollow layer 14 is formed in the metal pipe 10 is unnecessary, and the cost can be reduced. .
[0022]
Further, in the method of forming an FRP tube according to the present embodiment, since an autoclave device need not be used, the process can be simplified as compared with a conventional method using an autoclave device, and cost can be reduced.
[0023]
Furthermore, since the FRP prepreg 18 laminated on the metal mandrel 16 is uniformly pressurized over the whole by the expansion of the resin 12, even a thick tube can be easily formed without requiring any special operation. Pressurization can be performed.
[0024]
In the above description, the metal pipe 10 is filled with the resin 12 having a high expansion coefficient so that the cavity layer 14 is formed. However, other materials than the resin 12 may be used. It is. In other words, any material can be used as long as the material has a sufficiently large difference in thermal expansion from metal and the cavity layer 14 can be filled by expansion when the curing temperature of the resin impregnated with the FRP prepreg 18 is applied. Therefore, how much the width of the cavity layer 14 (the distance between the surface of the resin 12 and the surface of the FRP prepreg 18) when the metal mandrel 16 is inserted into the metal pipe 10 is determined by the material filled in the metal pipe 10. The material that can be used is determined by the amount of the metal pipe 10 (ie, the thickness of the metal pipe 10).
[0025]
【The invention's effect】
As described above in detail, according to the present invention, the expansion ratio of the FRP prepreg laid up on the mandrel in the hollow layer provided at the center formed by the material filled in the cylindrical pipe is increased. By press-molding the entire outer peripheral portion with a uniform pressure by expansion due to heating of a material having a high value, the quality of the appearance after tube molding can be improved and the number of molding steps can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a process of forming an FRP tube by a method of forming an FRP tube according to an embodiment.
FIG. 2 is a flowchart for explaining steps of a method of forming an FRP tube.
FIG. 3 is a view for explaining a conventional method for forming an FRP tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Metal pipe 12 ... Resin 14 ... Cavity layer 16 ... Metal mandrel 18 ... FRP prepreg

Claims (1)

A material having a higher expansion coefficient than metal is filled between the pipe and the hollow layer so that a hollow layer is provided at a central portion in the cylindrical pipe, and a fiber reinforeced plastic (FRP) is filled in the hollow layer. Insert the metal mandrel laid up prepreg, apply heat to the curing temperature of the FRP prepreg, expand the material, fill the cavity layer, press-mold the FRP prepreg, and cool after completion of pressurization Forming a hollow layer by shrinking the material to pull out the metal mandrel.

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