JP2845986B2 - Bending method of composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for bending a composite material for forming a prepreg of a fiber-reinforced composite material in which fibers are laminated in a mesh shape.
Especially when forming a gate-shaped structure from the reference surface and the flange surface hanging down from both sides, even if the connecting edge between the reference surface and the flange surface is curved, wrinkles and streaks are generated. The present invention relates to a method for bending a composite material which can be formed without any problem.

(Prior Art) Conventionally, a method of forming a prepreg of a fiber reinforced composite material in which fibers are laminated on a mesh is disclosed in, for example, JP-A-59-129-1.
No. 9119, a method of manually loading a composite material into a molding die one by one and stacking the composite material, or a vacuum method as disclosed in Japanese Utility Model Application No. 62-26838. There is known a method in which molding is performed using pressure and a vacuum bag and a side block.

(Problems to be Solved by the Invention) In the conventional molding method, the former method of manually laminating is performed by manual molding, so that the quality of molded products varies, and the number of laminating steps increases, resulting in heavy labor. In the case of a laminate having a curved surface, complicated hand movements and skill are required in order to form a desired shape. Also,
Since the working time is long, there is a problem that the expiration date of the prepreg is short, and it is difficult to laminate large components.

On the other hand, the latter using a vacuum bag is capable of laminating large parts with a short working time, but when the side block is lowered, there is a case where the force for pressing the prepreg and the vacuum bag against the side block does not work. In this case, there are problems such as generation of wrinkles and kinks in the bent portion of the prepreg.

Further, in any of the conventional molding methods, a composite material in which the connecting edge between the reference surface and the flange surface forms a curve, such as a deformed reference surface for forming or a curved bent portion. In the case of bending, there is a problem that wrinkles and streaks occur.

Therefore, the present applicant filed a patent application (filed on Heisei 1
(August 28, 2008) A bending method of a composite material that can be formed without causing wrinkles or streaks even when the connection edge between the reference surface and the flange surface is curved is proposed.

However, even with this method of bending and forming the composite material, wrinkles and streaks may be generated at the lower end of the flange surface,
If the reference surface is deformed in a waveform or the like, the prepreg may not adhere to the mold.

The present invention has been made in view of such a situation, and when forming a gate-shaped structure from a reference surface and a flange surface hanging down from both sides thereof, a connecting edge between the reference surface and the flange surface is curved. Even if it is not formed, it can be formed without causing wrinkles and streaks at all, and even if the reference surface is deformed, the prepreg can be bent and formed in close contact with the forming die The aim is to provide a method.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, as a means for achieving the above object, a gate is formed from a reference surface and a flange surface hanging down from both sides thereof, and a connecting edge between the reference surface and the flange surface is curved. The structure that forms
In a bending method of a composite material formed by prepreg of a fiber-reinforced composite material in which fibers are laminated in a mesh shape, a molding die for molding the reference surface and the flange surface, and a predetermined upper surface disposed on both sides of the molding die. A molding auxiliary mold having an upwardly projecting molding auxiliary piece at a position, an elevating mechanism for elevating and lowering the molding auxiliary mold so that it can be stopped at a predetermined position, and a prepreg formed by following the reference surface and pressing the prepreg from the upper side A pressing plate for forming the reference surface, and a pressing die formed of an elastic body expanded by gas and pressing the prepreg from the upper surface side of the pressing plate, and the prepreg, with respect to a connection edge between the reference surface and the flange surface, The prepreg is arranged so that the direction of the fibers is at an angle of approximately 45 °, and both ends of the prepreg on the flange surface side are cut in accordance with the shape of the connection edge, and the reference is made by the pressing plate. There while holding the both ends of the flange surface of the molded prepreg as a molding auxiliary and press die, characterized in that as lowers the molding auxiliary perform molding of the flange surface.

(Operation) In the method for bending a composite material according to the present invention, the prepreg is formed such that its fiber direction is at an angle of approximately 45 ° with respect to the connection edge between the reference surface and the flange surface. It is arranged on the upper surface of the forming auxiliary mold, and is pressed against the reference surface by the pressing plate from the upper surface side to form the reference surface. For this reason, even when the reference surface is deformed into a waveform or the like, it is possible to form the reference surface by bringing the prepreg into close contact with the mold. Next, the prepreg is clamped from above and below at both ends on the flange surface side by a pressing die and a forming auxiliary die, and in this state, the forming auxiliary die is lowered to form the flange surface. For this reason, the prepreg is formed while being pulled downward, and both ends of the prepreg on the flange surface side are cut in accordance with the shape of the connection edge, so that a dub occurs at the lower end of the flange surface. Since there is no wrinkle, there is no possibility that wrinkles or streaks will occur even at the lower end of the flange surface.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of an apparatus for carrying out a method for bending and forming a composite material according to the present invention.
This is a mold placed on a heated base 2, and this mold 1 is heated to a predetermined temperature in order to facilitate molding of a prepreg 3 described later.

The molding die 1 is, as shown in FIGS. 2 and 3,
A reference surface 4 for molding and a flange surface 5 hanging down from both sides of the reference surface 4 are provided with a gate-shaped forming surface, and the reference surface 4 includes a peak 6a and a valley 6b in a longitudinal direction. Are formed so that the connecting edge 7 between the reference surface 4 and the flange surface 5 is curved.

As shown in FIGS. 1 and 3, a molding auxiliary mold 8 having an opening 8a in the center thereof through which the molding die 1 passes is installed on the outer peripheral portion of the molding die 1. As shown in FIG. 1, the spring is always pressed upward by a biasing force of a spring or a hydraulic mechanism 9 interposed between the base 2 and a predetermined position by being pressed from above by a pressing die 10 described later. It can be raised and lowered so that it can be stopped.
That is, in this embodiment, the spring or the hydraulic mechanism 9 is used.
Constitutes an elevating mechanism of the auxiliary molding die 8.

As shown in FIG. 3, on the upper surface of the molding auxiliary mold 8,
Corresponding to the crests 6a of the irregularities 6, there are provided molding auxiliary pieces 11 each having an upwardly convex semi-cylindrical shape, so that they can move up and down integrally with the molding auxiliary die 8.

As shown in FIG. 4, the prepreg 3 is formed of a fiber-reinforced composite material in which fibers 3a are laminated on a network of several to several tens of layers, and, as shown in FIG.
A cut portion 12 having a waveform following the unevenness 6 of the connection edge 7 is provided.

That is, as shown in FIG. 6, each of these cut portions 12 has a wave height h, a peak radius r ₁ , a valley radius r ₂ ,
Defining a wavelength 1 and, and the unevenness 6, as shown in FIG. 7, R ₁ H, a radius at the crest 6a of the height of the wave, the radius of the valley 6b R _2, actual length of the Wavelength Is defined as L, the following setting conditions are satisfied.

The prepreg 3 configured as described above is connected to the connection edge 7.
On the other hand, the fibers 3a are placed on the upper surfaces of the forming die 1 and the forming auxiliary die 8 so that the direction of the fibers 3a is approximately 45 °, and prior to pressing by the pressing die 10, as shown in FIG. Then, the reference surface is processed by pressing with the pressing plate 13, and then the flange surface is processed by pressing with the pressing die 10.

As shown in FIG. 8, the pressure plate 13 is formed of a rigid metal plate or the like formed into a waveform following the reference surface 4 of the molding die 1, and the pressure plate 13 is previously formed into a waveform. By pressing the prepared prepreg 3 against the reference surface 4 of the mold 1, the reference surface is formed.

On the other hand, as shown in FIG. 1a, the pressing die 10 is made of a heat-resistant rubber bag 10a having elasticity and high-temperature or normal-temperature pressure air 10b fed into the rubber bag 10a or as shown in FIG. 1b. An elastic and heat-resistant flat plate 10c as shown, and high-temperature or normal-temperature pressure air 1 fed into the internal space 10a.
The rubber bag 10a is inflated by the supply of the pressurized air 10b, and vertically sandwiches both ends of the prepreg 3 on the flange surface 5 side with the auxiliary molding die 8. By lowering the molding auxiliary mold 8 in the state,
The flange surface 5 is formed.

FIG. 9 shows the finished product 14 which has been bent in this way and the excess portion has been cut.

Next, a method of bending and forming a composite material according to the present invention will be described.

First, the prepreg 3 formed in a corrugated shape as shown in FIG. 8 is placed on the molding die 1 and the molding auxiliary die 8 in the state shown in FIG. Is formed. At this time, the pressing plate 13 is connected to the reference surface 4 of the mold 1.
Therefore, the prepreg 3 can be completely adhered to the irregularities 6 to form the reference surface.

Next, the prepreg 3 is pressed by the pressing die 10 from the upper surface side of the pressing plate 13. As a result, prepreg 3 becomes 10th
As shown in FIG. 11 and FIG. 11, it is in close contact with the upper surfaces of the auxiliary molding die 8 and the auxiliary molding top 11.

Next, when the pressure of the compressed air 10b in the rubber bag 10a is increased or the urging force of the spring or the hydraulic mechanism 9 is mechanically weakened, the forming auxiliary mold 8 gradually descends as shown in FIG. The molding of No. 5 is performed.

At this time, both ends of the prepreg 3 on the flange surface 5 side are
Since it is sandwiched from above and below by the forming auxiliary die 8 and the pressing die 10, it is pulled downward by the lowering of the forming auxiliary die 8, and by providing the forming auxiliary top 11 on the upper surface of the forming auxiliary die 8, the valleys of the unevenness 6 are formed. The part corresponding to 6b is the auxiliary molding piece 11
Spread between the sides. In addition, the cut portions 12 at both ends of the prepreg 3 prevent dub formation during molding. For this reason, there is no possibility that wrinkles or streaks are generated on the flange surface 5. This will be described in detail later.

When the molding auxiliary mold 8 is lowered to the lower end as shown in FIG. 13, the room temperature or cold pressure air 10b is supplied into the rubber bag 10a to cool the rubber bag 10a and the prepreg 3. The mold 1 is cooled from the base 2 side.

When the prepreg 3 has been sufficiently cooled, the pressing by the pressing die 10 is released to complete the molding. Then, by cutting the lower end of the flange surface, a finished product 14 shown in FIG. 9 is obtained.

 Next, generation of wrinkles and streaks will be described.

As shown in FIG. 14, the prepreg 3 has fibers laminated in a mesh pattern, but cannot be pulled in the arrow direction because the fibers do not stretch. Therefore, the prepreg 3 is pulled in the directions of arrows X and Y shown in FIG. 15, whereby the mesh of the prepreg 3 is a quadrilateral as shown by a solid line in FIG. Deforms into a rhombus, as if the fibers were stretched.

When the prepreg 3 is formed into the shape shown in FIG. 17, if the total length is A, the length of the reference surface portion 20 is A ₁ , and the length of the flange surface portion 21 is A ₂ , the reference surface portion 20 has irregularities. 6
A ₁ > A ₂ … (2)

Therefore, if this molding is simply performed, the difference A ₃
A dub is formed on the flange surface portion 21 by an amount of (A ₃ = A ₁ −A ₂ ), and appears as wrinkles and streaks 22 as shown in FIG. The wrinkles and the streaks 22 are formed in the valleys 6 b
Occurs in the portion corresponding to.

In order not to generate wrinkles and streaks 22 on the flange surface portion 21,
The following two methods are conceivable.

The first method is a method in which the prepreg 3 of the valley 6b is adhered to the mandrel while expanding the prepreg 3 in the ± 45 ° direction, and the second method is a method of forming the valley 6b in the ± 45 ° direction rather than forming the peak 6a. This is a method of spreading the fibers first.

As a means for realizing the first method, it is conceivable to clamp the prepreg 3 and mechanically pull it. In the case of hand lay-up, a hand can be pulled freely instead of a clamp, but it is extremely difficult and impractical to incorporate a clamp mechanism having the same function into a molding apparatus.

On the other hand, means for realizing the second method include the first method.
As in the embodiment, it is conceivable to use the forming auxiliary mold 8 and dispose the forming auxiliary top 11 on the upper surface thereof so as to satisfy certain conditions.

That is, as shown in FIG. 24, between the tops P ₁ and P ₂ of the peaks 6 a of the unevenness 6, the surface length of the unevenness 6, that is, the length of the connecting edge 7 is a, Assuming that the surface length of 8 and the auxiliary molding top 11 is b, the molding auxiliary top 11 is set so that a ≦ b (3). And the 25th
The prepreg 3 is formed as shown in FIG. 26 and FIG.
Then, the prepreg 3 in the valley portion 6b is moved to the auxiliary molding 11
Is pulled toward the lower end, and the same effect as hand lay-up can be obtained.

Moreover, since the cut portions 12 following the shape of the irregularities 6 are provided at both ends of the prepreg 3, even if the prepreg 3 at the valley portion 6 b is pulled toward the lower end portion of the forming auxiliary piece 11, Dubbing does not occur at the peaks 6a of the prepreg 3, and wrinkles and streaks 22 can be completely prevented.

Note that, in the example of the embodiment, the case where the finished product 14 in which the reference surface is deformed into a corrugated shape as shown in FIG. 9 has been described, but the finished product 14A having the shape shown in FIG.
Alternatively, the present invention can be similarly applied to the case of forming a finished product 14B having the shape shown in FIG. 28, and the same effect can be expected.

〔The invention's effect〕

As described above, the present invention arranges the prepreg such that the fiber direction is at an angle of approximately 45 ° with respect to the connection edge between the reference surface and the flange surface, and presses the prepreg with a pressure plate. While the reference surface is being formed, with the both ends of the prepreg on the flange surface side being sandwiched between the pressing die and the forming auxiliary die, the forming auxiliary die is lowered to form the flange surface, and the prepreg is formed on the flange surface side. Since both ends are cut corresponding to the shape of the connecting edge,
The prepreg can be folded and formed with sufficient contact with the reference surface and the flange surface of the mold. Moreover, the prepreg can be pulled by the forming auxiliary piece so that there is no looseness, and the cut portion of the prepreg eliminates the dub associated with pulling the prepreg with the forming auxiliary piece, so that the reference surface and the flange surface can be removed. Even when the connecting edge of the is curved, the generation of wrinkles and streaks can be completely prevented.

[Brief description of the drawings]

FIG. 1 is a structural view showing an example of an apparatus for carrying out a method of bending a composite material according to the present invention, FIGS. 1a and 1b show a pressing die, and FIG. 2 shows the structure of a forming die. FIG. 3 is a perspective view showing the relationship between the shape of the reference surface of the molding die and the setting position of the auxiliary molding piece, FIG. 4 is a perspective view showing the structure of the prepreg, and FIG. Perspective view showing a prepreg provided with a part, FIG. 6 is an enlarged view of a VI part of FIG. 5, FIG. 7 is a detailed view showing irregularities of a molding die, FIG. 8 is an explanatory view showing a method of molding a reference surface, FIG. 9 is a perspective view of a finished product processed by bending, FIG. 10 is an explanatory diagram showing an initial state of forming in a method of bending and forming a composite material using the apparatus shown in FIG. 1, and FIG. Is a cross-sectional view taken along the line XI-XI in FIG. 10, FIG. 12 is a diagram corresponding to FIG. 11, showing a similar state during molding, and FIG. 13 is a phase diagram showing a similar state at the end of molding. FIGS. 14 to 16 are explanatory diagrams showing the direction of elongation of the prepreg, FIGS. 17 and 18 are explanatory diagrams showing the relationship between the molded shape and the occurrence of wrinkles and streaks, FIGS. 19 to FIG. 22 is an explanatory view showing a mechanism in which wrinkles and streaks are generated in a portion corresponding to an uneven valley portion of a flange surface portion. FIG. Fig. 24 is an explanatory diagram showing the running of
FIG. 23 is an explanatory diagram showing conditions of forming auxiliary pieces for obtaining fiber running as shown in FIG. 23, FIG. 25 is an explanatory diagram showing a state of forming a prepreg under these conditions, and FIG. 26 is a diagram of FIG. XXVI
FIG. 27 and FIG. 28 are perspective views showing finished products having different shapes, respectively. 1 ... mold, 3 ... prepreg, 3a ... fiber, 4 ...
Reference surface, 5: Flange surface, 6: Unevenness, 7: Connecting edge, 8: Forming auxiliary mold, 9: Spring or hydraulic mechanism, 10: Press mold, 10a: Rubber bag, 10b: Pressure Air, 11: Molding auxiliary frame, 12: Cut part, 13: Pressure plate.

──────────────────────────────────────────────────の Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 70/04 B29C 53/04

Claims (1)

(57) [Claims] 1. A fiber reinforced composite material in which fibers are laminated in a mesh form, with a structure having a gate shape from a reference surface and a flange surface hanging down from both sides thereof and a connecting edge between the reference surface and the flange surface forming a curve. In the method of bending a composite material formed by the prepreg, a molding die for molding the reference surface and the flange surface, and a molding auxiliary piece arranged on both sides of the molding die and projecting upward at a predetermined position on the upper surface are provided. A forming auxiliary mold, an elevating mechanism for raising and lowering the forming auxiliary mold so as to be able to be stopped at a predetermined position, a pressing plate having a shape following the reference surface and pressing the prepreg from the upper surface side to form the reference surface, A press die that is formed of an elastic body that expands and presses the prepreg from the upper surface side of the pressure plate, and the direction of the fiber is approximately the same as that of the prepreg with respect to the connection edge between the reference surface and the flange surface.
The prepreg is arranged so as to have an angle of 45 °, and both ends of the prepreg on the flange surface side are cut in accordance with the shape of the connecting edge, and the reference surface is formed on the flange surface side of the prepreg formed by the pressing plate. And forming the flange surface by lowering the forming auxiliary die while holding both ends of the pressing member as a pressing die and a forming auxiliary die.