Method and apparatus for manufacturing preforms

Abstract

To solve the problem of wrinkling, in conventional preform manufacturing method, when shaping a preform with a three-dimensional convex shape in a center.SOLUTION: A manufacturing method for shaping a preform P includes: placing a fiber laminate S with a frame 5 on an upper side of a mold 2, while a periphery of the fiber laminate S is held by the frame 5; covering the mold 2, the fiber laminate S, and the frame 5 with an airtight sheet 3; then bringing the fiber laminate S into close contact with an outer surface of the mold 2, while moving the frame 5 downward of the mold 2, by evacuating air from an internal space of the airtight sheet 3. The preform P has a three-dimensional convex shape in a center, and the frame 5 applies uniform surface pressure to the fiber laminate S to provide the preform P with high shape accuracy without forming defects such as wrinkles.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing a preform used for shaping a preform of a fiber reinforced composite material into a predetermined shape.

Background Art

[0002] Conventionally, as a method for manufacturing a preform, for example, there is one described in Patent Document 1. In the method for manufacturing a preform described in Patent Document 1, a convex jig is disposed on a molding die, and after a fiber laminate made of a reinforcing fiber base material is disposed on the jig, the jig and the fiber laminate are covered with a sheet, and the inside of the sheet is depressurized to apply a surface pressure to the sheet, thereby shaping the fiber laminate into a preform having a predetermined shape between the sheet and the jig. At this time, in the above-described method for manufacturing a preform, by not adhering the sheet to the corner portion between the molding die and the jig, it is intended to obtain a preform having excellent surface properties.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional method for manufacturing a preform as described above, there are limitations in the shape of the preform. That is, in the above-described method for manufacturing a preform, for example, when shaping a preform having a three-dimensional convex shape in the center, it is difficult to apply a uniform surface pressure to the entire circumference of the convex shape, so there is a problem that wrinkles occur, and solving such a problem has been an issue.

[0005] [ This invention has been made in view of the above-mentioned conventional problems, and aims to provide a method and apparatus for manufacturing preforms that can form preforms with high shape accuracy, free from molding defects such as wrinkles, even when the preform has a three-dimensional convex shape in the center. [Means for solving the problem]

[0006] The present invention relates to a method for manufacturing a preform, in which a fiber laminate is placed on the upper side of a convex mold and covered with an airtight sheet, and then the internal space of the airtight sheet is evacuated to bring the fiber laminate into close contact with the outer surface of the mold, thereby manufacturing a preform made of a fiber laminate. The method for manufacturing a preform uses a ring-shaped frame into which the mold can enter, and the periphery of the fiber laminate is held by the frame, and the fiber laminate is placed on the upper side of the mold together with the frame, and the mold, the fiber laminate and the frame are covered with the airtight sheet. Subsequently, the method for manufacturing a preform is characterized by moving the frame downwards from the mold while evacuating the internal space of the airtight sheet, thereby bringing the fiber laminate into close contact with the outer surface of the mold, thereby forming a preform made of a fiber laminate.

[0007] The preform manufacturing apparatus according to the present invention is an apparatus used in the above-described method for manufacturing a preform, and is characterized by comprising: a chamber open on the upper side; a mold placed inside the chamber; an airtight sheet sealing the opening of the chamber; an exhaust device for evacuating the internal space of the chamber; and a frame that is ring-shaped into which the mold can enter and which holds the peripheral edge of the fiber laminate. [Effects of the Invention]

[0008] The preform manufacturing method and manufacturing apparatus according to the present invention, by adopting the above configuration, makes it possible to apply uniform surface pressure to the fiber laminate by pressing down on the entire peripheral edge of the fiber laminate with the frame, even when the shape of the preform has a three-dimensional convex shape in the center, thereby forming a preform with high shape accuracy that is free from molding defects such as wrinkles. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional diagram illustrating a first embodiment of a method for manufacturing a preform and a manufacturing apparatus according to the present invention. [Figure 2] This is a plan view of the manufacturing apparatus shown in Figure 1, with the airtight sheet omitted. [Figure 3] These are cross-sectional diagrams illustrating the manufacturing process of preforms in sequence. [Figure 4] This is a cross-sectional diagram illustrating a second embodiment of a method for manufacturing a preform and a manufacturing apparatus according to the present invention. [Figure 5] Following Figure 4, this is a cross-sectional diagram illustrating the state when the internal space of the airtight sheet has been evacuated. [Modes for carrying out the invention]

[0010] <First Embodiment> Figures 1 and 2 illustrate a manufacturing apparatus applicable to the method for manufacturing a preform according to the present invention. In the method for manufacturing a preform and the manufacturing apparatus described below, a preform P having a three-dimensional convex shape in the center is formed from a fiber laminate S. The fiber laminate S is, for example, made by laminating multiple fiber base materials with different fiber orientations, using carbon fibers as reinforcing fibers, and containing a binder, and initially has a flat plate shape.

[0011] The illustrated example manufacturing apparatus has a basic configuration comprising a chamber 1 that is open on the top, a mold 2 placed inside the chamber 1, an airtight sheet 3 that seals the opening of the chamber 1, an exhaust device 4 that evacuates the internal space of the chamber 1, and a ring-shaped frame 5 into which the mold 2 can enter. The illustrated example manufacturing apparatus also includes a supporter 6 that supports the frame 5 above the mold 2, and a breather 7 laid on the bottom surface of the chamber 1.

[0012] Chamber 1 is a rectangular housing that is open on the top and has a removable fixing frame 1A on the top, which clamps the periphery of the airtight sheet 3 that covers the opening. The material of the airtight sheet 3 is not particularly limited as long as it is flexible and airtight, but silicone rubber can be used as an example.

[0013] The mold 2 has a shaping section 2B in the center of the base 2A that forms a three-dimensional convex shape. In the plan view shown in Figure 2, the shaping section 2B has an elliptical shape, and in the side view shown in Figure 1, the flat top surface and the inclined side surface are smoothly continuous by a curved surface, and the side surface and the top surface of the base 2A are smoothly continuous by a curved surface.

[0014] Although detailed illustrations are omitted, the exhaust system 4 consists of a vacuum pump and various control valves, and evacuates (reduces pressure) the internal space of the airtight sheet 3, or more precisely, the lower space of the chamber 1 partitioned by the airtight sheet 3, through the vent 1B located near the bottom of the chamber 1 and the external piping 4A.

[0015] The frame 5, in the plane shown in Figure 2, is an elliptical ring shape corresponding to the shaping portion 2B of the mold 2, and is sized to face the upper surface of the base 2A. It also has the rigidity to withstand atmospheric pressure during vacuuming, and is made of metal, for example. The size and circumferential width dimensions of this frame 5 are appropriately set according to the thickness of the fiber laminate S and the shape of the central convex shape (shape of the shaping portion 2B). For this reason, the width dimension of the frame 5 may be uniform around the entire circumference or vary in parts.

[0016] The above-mentioned frame body 5 moves within a range from the upper limit position above the shaping portion 2B to the lower limit position where it contacts the pedestal 2A of the mold 2. Further, the frame body 5 has a function of holding the peripheral portion of the fiber laminate S. For this reason, the frame body 5 includes an upper frame 5A and a lower frame 5B, and as shown in the enlarged view in FIG. 1, magnets 8A and 8B are provided at positions where the two frames 5A and 5B face each other. This frame body 5 holds the peripheral portion of the fiber laminate S between the two frames 5A and 5B and positions the two frames 5A and 5B relative to each other by the magnets 8A and 8B. In order to ensure the positioning accuracy, it is more preferable to arrange the pair of magnets 8A and 8B at a plurality of locations.

[0017] [[ID=​​​​​​​​​​​​The method for manufacturing a preform using the above manufacturing apparatus is as follows. As shown in the upper left part of FIG. 3, a breather 7 is laid inside the chamber 1 and the molding die 2 is arranged. Next, as shown in the middle left part of FIG. 3, supporters 6 are arranged at four locations on the pedestal 2A of the molding die 2, and the lower frame 5B of the frame body 5 is supported by each supporter 6, and the fiber laminate S is arranged above the lower frame 5B. Then, as shown in the lower left part of FIG. 3, the upper frame 5A is positioned with respect to the lower frame 5B, and the peripheral edge portion of the fiber laminate S is sandwiched and held between the upper frame 5A and the lower frame 5B. As a result, the fiber laminate S held by the frame body 5 is arranged above the molding die 2.

[0021] Next, in the method for manufacturing a preform, as shown in the upper right part of FIG. 3, the open part of the chamber 1 is covered with an airtight sheet 3, and its peripheral edge portion is fixed with a fixing frame 1A. At this time, the airtight sheet 3 is curved downward by its own weight and contacts the upper surface of the fiber laminate S held by the frame body 5. Then, in the method for manufacturing a preform, the internal space of the airtight sheet 3, that is, the lower space of the airtight sheet 3 in the chamber 1, is evacuated (depressurized) by the exhaust device 4.

[0022] As a result, in the method for manufacturing a preform, atmospheric pressure acts on the upper surface of the airtight sheet 3, and while moving the frame body 5 downward with respect to the molding die 2, the fiber laminate S is brought into close contact with the outer surface of the shaping portion 2B of the molding die 2. At this time, since the fiber laminate S is deformed from a planar shape into a three-dimensional convex shape, the peripheral edge portion will be pulled toward the center. However, since the entire peripheral edge portion is suppressed by the frame body 5, it is deformed along the outer surface of the shaping portion 2B and finally comes into close contact with the shaping portion 2B.

[0023] Also, in the above method for manufacturing a preform, as shown in the middle right part of FIG. 3, the frame body 5 is moved downward with respect to the molding die 2 while the supporter 6 is contracted downward, and the shaping portion 2B of the molding die 2 penetrates into the inside of the lowered frame body 5.

[0024] In this way, the preform manufacturing method and manufacturing apparatus shape a preform P consisting of a fiber laminate S. Furthermore, in this embodiment, as shown in the middle right of Figure 3, the shaped preform P is heated by a heating device 11 to harden the binder and maintain the shape of the preform P.

[0025] Subsequently, the manufacturing method of the preform involves opening the lower space of the airtight sheet 3 to the atmosphere, removing the airtight sheet 3 from the chamber 1, and then removing the upper frame 5A of the frame 5 to demold the preform P, as shown in the lower right section of Figure 3.

[0026] According to the preform manufacturing method and manufacturing apparatus described in the above embodiment, even if the preform P has a three-dimensional convex shape in the center, by pressing down on the entire peripheral edge of the fiber laminate S with the frame 5, it is possible to apply uniform surface pressure to the fiber laminate S, and a preform P with high shape accuracy that is free from molding defects such as wrinkles can be formed.

[0027] Furthermore, the above-described preform manufacturing method and apparatus stabilize the posture of the frame 5 and the fiber laminate S by supporting the frame 5 with a shrinkable supporter 6, allowing the frame 5 to be lowered while maintaining a horizontal position, thereby applying more uniform surface pressure to the fiber laminate S. This prevents misalignment of the fiber substrates in the fiber laminate S, contributing to further improvement in the shape accuracy of the preform P.

[0028] Furthermore, in the above method for manufacturing preforms, the molded preform P is heated and hardened, which simplifies the release process of the preform P and improves handling of the preform P in subsequent processes.

[0029] Furthermore, in the above-mentioned preform manufacturing apparatus, by using a frame 5 with rigidity that can withstand atmospheric pressure during vacuuming, the function of holding down the fiber laminate S is stabilized, enabling uniform surface pressure to be applied to the fiber laminate S and preventing misalignment between the fiber substrates.

[0030] Furthermore, in the above-described preform manufacturing apparatus, by installing a breathable breather 7 on the bottom surface of the chamber 1, it is possible to suppress the formation of air pockets under the airtight sheet 3 during vacuuming (reducing pressure), which contributes to the good shaping of the preform P.

[0031] <Second Embodiment> Figures 4 and 5 illustrate a second embodiment of the method and apparatus for manufacturing a preform according to the present invention. In this embodiment, the same reference numerals are used for the same parts as in the first embodiment, and detailed descriptions are omitted.

[0032] The method for manufacturing a preform and the manufacturing apparatus according to the present invention make it possible to omit the supporter (6) described in the first embodiment. As shown in Figure 4, if the central convex shape of the preform P, that is, the forming portion 2B of the mold 2, has a flat top surface and a substantially uniform outer surface (cross-section) around its entire circumference, the fiber laminate S, whose peripheral edge is held by the frame 5, is placed directly on the upper side of the forming portion 2B without using the supporter (6). Since the fiber laminate S contains a binder, it can be placed on the mold 2 while maintaining a flat plate shape.

[0033] Furthermore, in the illustrated manufacturing apparatus, as shown in the enlarged view in Figure 4, the frame 5 is positioned relative to the upper frame 5A and the lower frame 5B by inserting a pin 12 provided in the upper frame 5A into a hole 13 in the lower frame 5B. It is preferable to provide pins 12 and holes 13 in multiple locations. Moreover, in order to prevent damage to the airtight sheet 3, it is preferable to provide the pin 12 in the upper frame 5A as shown in the illustrated example, and if it is provided in the lower frame 5B, the tip should be structured so that it does not protrude above the frame 5.

[0034] In the above-described method and apparatus for manufacturing preforms, during vacuuming (reducing pressure), the atmospheric pressure acting on the airtight sheet 3 is applied almost equally to the frame 5 and the fiber laminate S. As a result, the frame 5 is pushed down while maintaining a horizontal position, causing the fiber laminate S to adhere tightly to the shaping section 2B, as shown in Figure 5.

[0035] As a result, the above-described preform manufacturing method and apparatus make it possible to apply uniform surface pressure to the fiber laminate S, similar to the first embodiment, and to form a preform P with high shape accuracy that is free from molding defects such as wrinkles. In particular, since the above-described preform manufacturing method and apparatus do not use a supporter (6), the work is simplified and maintenance costs are reduced, thus enabling a reduction in manufacturing costs.

[0036] The preform manufacturing method and manufacturing apparatus according to the present invention are not limited to the above embodiments, and can be modified as appropriate without departing from the spirit of the present invention. Furthermore, although the above preform manufacturing method and manufacturing apparatus have been described as forming a fiber laminate S, which contains a binder in a fiber substrate, onto a preform P, it is also possible to apply the manufacturing method to a process in which the fiber laminate S contains reinforcing fibers and a matrix resin, and this is formed into a product shape and heat-cured, i.e., to the manufacture of fiber-reinforced composite materials. [Explanation of Symbols]

[0037] P Preform S fiber laminate 1 Chamber 2 Molding mold 3. Airtight sheet 4. Exhaust system 5 Frame 6 Supporters 7 Breather

Claims

1. When manufacturing a preform made of a fiber laminate by placing a fiber laminate on the upper side of a convex mold and covering it with an airtight sheet, and then vacuuming the internal space of the airtight sheet to bring the fiber laminate into close contact with the outer surface of the mold, Using a ring-shaped frame into which the mold can be inserted, With the peripheral edge of the fiber laminate held by the frame, the fiber laminate is placed together with the frame on the upper side of the molding die. After covering the mold, the fiber laminate, and the frame with the airtight sheet, A method for manufacturing a preform, characterized by evacuating the internal space of the airtight sheet, thereby moving the frame downwards to the mold, and bringing the fiber laminate into close contact with the outer surface of the mold to form a preform made of the fiber laminate.

2. Using a retractable supporter, The supporter supports the frame above the mold, The method for manufacturing a preform according to claim 1, characterized in that the supporter is contracted by evacuating the internal space of the airtight sheet, thereby moving the frame downward to the mold.

3. The method for producing a preform according to claim 1, characterized in that the preform is shaped and then heated to cure it.

4. Apparatus used in the method for manufacturing a preform as described in claim 1, A preform manufacturing apparatus comprising: an open chamber on the upper side; a mold disposed inside the chamber; an airtight sheet sealing the open portion of the chamber; an exhaust device for evacuating the internal space of the chamber; and a frame that is ring-shaped into which the mold can enter and which holds the peripheral edge of the fiber laminate.

5. The preform manufacturing apparatus according to claim 4, characterized in that it is contractible and includes a supporter that supports the frame on the upper side of the mold.

6. The preform manufacturing apparatus according to claim 4, characterized in that the frame has rigidity to withstand atmospheric pressure during vacuuming.

7. The preform manufacturing apparatus according to claim 4, characterized in that a breathable breather is laid on the bottom surface of the chamber.

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