JPS5856823A - Production of structure of composite material - Google Patents

Abstract

PURPOSE:To produce a structure of a composite material inexpensively and with high accuracy, by a method wherein, when a material to be molded consisting of a fiber-reinforced resin and a core are sealed in a metallic mold having a desired shape and the material is molded under heating while pressurizing the interior of the core, the core is produced by inserting a core made of a foamed material into a pressure bag consisting of an adhesive film. CONSTITUTION:In a method for producing a structure of a composite material wherein the material 58 to be molded consisting of a fiber-reinforced resin and the core 42 is sealed in the metallic mold 60 having the desired shape and the material 58 is molded under heating while pressurizing the interior of the core 42, the core 42 is produced by a method wherein a core 42 made from a thermoplastic foarmed material and being slightly smaller than a desired size is inserted into the pressure bag 40 prepared by jointing an adhesive film. The material 58 is molded under heating while exerting a pressure on the bag 40 of the core 42 so that the bag 40 is adhered to the material 58, and after molding is completed, the residue of the thermoplastic foamed material shrunk in the interior of the bag 40 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a structure made of a so-called resin-based composite material, which is a combination of fibers and synthetic resin.

Conventionally, resin-based composite materials such as glass fibers, organic fibers, carbon fibers, etc.
Examples of methods for manufacturing a structure using a laminated sheet material impregnated with a liimide resin include an autoclave method and a hot press method. All of these methods are suitable for molding relatively thin, large-area flat molded products, but are unsuitable for molding three-dimensional structures.

To be more specific, in the conventional autoclave method and hot press method, first, a flat panel is manufactured and then assembled to manufacture a structure. However, autoclave molding does not provide dimensional accuracy on one side, resulting in poor assembly accuracy. Furthermore, flat structures tend to suffer from molding distortion due to the anisotropy characteristic of composite materials. In the case of adhesive assembly, it is necessary to control the adhesive thickness adjustment with an accuracy of about 0.1 mm, but accurate positioning is difficult for the above-mentioned reasons. Furthermore, since composite materials are susceptible to stress concentration, if an assembly method using nuts, rivets, etc. is used throughout, the weight and processing cost will increase.

On the other hand, aircraft wings, ailerons, various types of propellers 42
, fan blades, etc. are all hollow objects with complex internal structures, and their performance is determined by the accuracy of their outer circumference dimensions, making them unsuitable for molding using the autoclave method or hot press method described above. It's a roar.

Therefore, there is a method of molding by using a sealed metal lid that gives accurate external dimensions, inserting a pressurized bag that can be expanded under pressure, and pressing the molded object outward from the inside, as disclosed in U.S. Patent No. 5. , No. 715,755, Japanese Unexamined Patent Publication No. 14298/1980, etc. However, even with this method, it was difficult to accurately mold the internal structure. This is especially a problem if there is a web-like partition inside.

That is, in this method, since the pressure bag is thin and flexible, as shown in FIG.
When the pressure bag 16 is put in, the top mlg is placed on it, and the pressure bag is pressurized and molded, it does not always expand at the same rate.
As shown in the 1st BvAK, Tsu! 7" 14 is tilted, creating a corner l5Ktl cavity 20.

In addition, as shown in Fig. 2^, in the method in which the web 12 is laminated in HmK in advance and formed, if the pressurizing force is initially small, the pressurized bag 16 will form in the corner part 22 as shown in Fig. 2B. Bag 16 that does not stick tightly and increases pressure force
As it expands and moves, it passes through the state shown in Figure 2C and changes to the second
As shown in FIG. 0, wrinkles 24 may occur on the sea urchin 114. In addition, if the pressure bag 16^ in Fig. 2E is not in close contact with the corner of the sea urchin f14 from the beginning and there is not enough room for the pressure bag to stretch, the web will not wrinkle. The pressure bag 16BC) is in a medium-sized state.

Since the pressure is supported by the thin pressure bag itself, an accident occurs in which the pressure bag ruptures as shown by reference numeral 26 in 2F5AK due to the increased pressure.

To eliminate the above-mentioned problems, it is first necessary to place a pressurized bag in close contact with a portion of each corner. For this purpose, a method is proposed in JP-A No. 54-15571 (Japanese Patent Application No. 52-78651), in which the rigidity of the pressurized bag itself is slightly reduced to maintain its shape and form the final shape from the beginning.
Therefore, it is proposed. This method requires a ninth mold to accurately shape the pressurized bag in advance. This causes the following problems. That is, in the case of high-mix low-volume production such as aircraft, it becomes expensive to prepare many types of molds. Furthermore, even slight changes in the general design of small parts may require the deaf to be rebuilt. Usually, the external shape is determined by aerodynamic or structural requirements, and the wall thickness and placement of composite structures are also determined by mechanical requirements.
The inner shape is extremely complex. It takes a large amount of money to manufacture a log with such a complicated shape.

Furthermore, if there are variations in the dimensions of each part of the inner mold to create such a complex shape, this will accumulate throughout the entire inner mold, and the dimensional accuracy of the inner mold will inevitably deteriorate. However, this does not necessarily mean that the above problem will be resolved.

Furthermore, in the method of JP-A No. 54-15571, since the pressurized bag itself supports the molded object from the inside so as to determine the internal shape of the composite material structure, in order to prevent each bag from becoming soft, the material must be thick to a certain extent. It is necessary to use a film, and the invention in the patent publication also states that it is 0.1 or more. However, even this can be said to be heavy for the structure of a small aircraft. Further, if the shape of the pressure bag and the shape of the composite material structure O do not match, the pressure bag may be crushed and the shape may be greatly distorted.

Since the pressure bag is relatively thick, the bag itself supports the pressure at corners with a small radius, and no pressure is applied to the composite structure.
In some cases, products with bubbles were produced.

Another method is to use a thin thermoplastic film as a pressurized bag, cover it with a mold that can be disassembled, and then insert it inside. However, this method also has the following drawbacks. Namely.

After the molding of the composite material structure is completed, it is necessary to pull it out from this AT opening, which requires a very complicated structure. For example, you can make a shape that can be unfolded, folded and folded like an umbrella, or make it divisible like marquetry, or make a shape that can be divided like a parquet. Peck and destroy the plaster*
There were other methods such as leaving. However, all of these methods require a lot of effort to produce the mold itself.

In particular, when the external shape is determined by aerodynamics and the structure and thickness of the parts are determined by strength, as in the case of the wings of the Aircraft 2, the internal dimensions and shape become extremely complex. It is difficult and expensive to make a mold with a complicated external shape, and the heat capacity of the mold itself is large, so the temperature distribution during hot molding is difficult. or increase the variation in strength. Furthermore, it requires a large amount of money and time to modify the mold in response to design changes during prototype production. In addition, because the mold is complex, it often interferes with composite material structures, damaging and rupturing the thin pressurized bag, and distorting the internal structure.

SUMMARY OF THE INVENTION Therefore, the present invention aims to eliminate the various drawbacks mentioned above and provide a method for manufacturing composite structures at low cost and at a high cost of 11%.

That is, according to the present invention, 1-1 gives the required shape.
A method for manufacturing a composite material structure in which a molded article made of synthetic resin and reinforcing fibers and an inner mold are sealed in a monolithic mold, and the inside of the inner mold is heat-molded while being heated. is made by bonding thin adhesive films.
M made from a thermoplastic foam material slightly smaller than the required size is inserted into one bag, and ML thermoforming is performed while applying pressure to the pressurized bag in the inner mold to form the pressurized loan. In addition to adhesively bonding to the object, the remaining material of the contracted thermoplastic foam material in the pressure bag is removed after the molding is completed.

According to such a method, the above-mentioned Japanese Patent Application Publication No. 54-1357
In addition to exhibiting all the effects of the method disclosed in No. 1, the pressurized bag is supported by a mold made of thermoplastic foam material, so it can be made thinner and lighter than most people, resulting in the advantages of composite materials. It is possible to take advantage of this, and the weight of the structure with the belly joint can also be made lighter.

No fever in the ward! The mold for lactic foam can be easily made without the need for special jigs or equipment, and the inner mold can be made by simply inserting the mold into a pressurized bag, so the inner mold can be made at a very low cost.
You can also produce a wide variety of raw sparrow in small numbers at a price that is not much different from that of a large number of raw sparrows. 9. Since thermoplastic@foam materials can be molded into any shape very easily, the inner lj1 can be easily formed into any shape. At that time, the mold of the foam material may also interfere with some of the corners of the web! 7FIII without making l
Since the K-bag can be tightly packed, there will be no wrinkles in the web.

Further, since the processing bag is thin and the pressure is applied to every corner of the processing bag, the internal shape of the composite material structure can be formed into a desired shape with high precision. *The thermally 0Tffi foam material shrinks to several tens of minutes to several six minutes of its original volume due to the heat generated during molding of the composite structure, so it can be easily removed even from a small outlet.

And since the thermoplastic foam material #i is suitably soft,
Even if there is interference between the uncured composite structure and the thermo-q-plastic foam material mold, there will be no problem such as damage to the pressure bag or distortion of the shape of the structure. Since the bag is thin, wrinkles in the pressure bag itself are rarely a problem for composite structures.

Note that if the surface of the thermo-qffi foam material mold is not smooth, the pressure bag may be damaged.

(9) After thermoforming, the remaining material of the contracted thermoplastic foam material adheres to the bag and runs off due to the adhesive used when making the mold of the foam material (h<-1〃atf). In order to prevent this, a pressure mold made of thermoplastic foam material is wrapped in a heat-resistant film and placed in the pressure bag, and after the molding is completed, the heat-resistant film t1 shrinks and the remaining thermoplastic material is removed. Remove with wood.

In this way, since the mold for the foam material is wrapped in a heat-resistant film, it is easy to insert the mold into the pressurized bag, and when the film r is pulled out after molding, it contracts at the same time, making it easy to remove the remaining material from the pressure mold. It is removable and convenient.

Embodiments of the method according to the invention will now be described with reference to the accompanying drawings.

FIG. 3 is a perspective view of a hollow rotor blade of a helicopter, and FIG. 38 is a cross-sectional view taken along line 3A in FIG. 3A. The rotor blade 30 has a hollow hole 32 and a hole 34 and an opening 36 for the root mounting bolt.

In order to make such a rotor blade, according to the present invention, adhesive thermoplastic glass films are first pasted together to form a hollow part 32 of approximately the same size as shown in FIG. 4A. Make 40 pressurized bags. However, the hollow part 32
It does not necessarily have to be the same shape. Then, a mold 42 as shown in FIG. 48, which is slightly smaller in size than the hollow portion 32, is made of a thermoplastic foam material such as expanded polystyrene.

This mold 42 can also be made at once by making the top and bottom of the mold 44T as shown in FIG. This method can generate a large number of W42 in a short time.
can be made and is inexpensive. Furthermore, the surface can be made smooth.

Also, the mold 42 has parts 42^, 428.42G, 42D
Since it can be divided into 4 parts, it can also be made by attaching it in 4 parts and then bonding them together with a layering agent. In this case, as shown in FIG. 6A, a styrofoam material 5 is placed on a plate 48 provided with templates or templates 46 on both sides.
0t-, cut off the upper part of the wood by moving the direct heating line 52 on the tenten rate, and then cutting off the top 01lI of the wood by moving the direct heating line 52 as shown in Fig. 68.
By cutting at 152, a portion 42B as shown in FIG. 6C can also be made.

The W42 made as above is inserted into the D0 pressure bag 40 as shown in FIG. 4C, and then as shown in FIG.
The uncured composite material sheet 581 is placed on the lower die 60 of the laminated rigid metal sheet, and the rigid full-length upper mold H164 on which the uncured composite material sheet 62 is uniformly laminated is placed over it and closed. The interior of the molds 60 and 64 is then evacuated to force the uncured composite sheets 58 and 62 onto the mold interior surfaces and settle them into their predetermined positions. Thereafter, while applying pressure to the pressurized bag number, the upper and lower W2O and 64 are heated and molded. The bundle, pressurized bag 4o is molded due to its laminated properties, i.e., the rotort 3o of FIG. 3A.
Glue to. On the other hand, the shrunk leftover material of Styrofoam is
Remove from opening 36.

In the method described above, inner Wf made of styrofoam:
Since the pressurized bag is densely layered inside the bag beforehand, the above-mentioned problems are eliminated and a stable strike shape can always be obtained. Furthermore, since Styrofoam is very soft, even if the uncured composite structure and the Styrofoam mold interfere, there will be no problems such as distortion of the shape of the structure caused by smoke damage to the pressure bag. Furthermore, the inner mold made of styrofoam does not require special jigs or equipment to manufacture it. That is, as mentioned above, the Styrofoam mold consists of two templates and a hot wire, it can be easily processed in large quantities, and it is also very inexpensive, and the design can be changed by changing the tensile rate. is also easy. Moreover, if a mold as shown in Fig. 5 is used, a great deal of cost savings will be achieved.

Furthermore, the styrofoam shrinks to several tenths to several hundredths of its original volume due to the heat generated during molding of the composite structure, so it can be easily taken out even through a small outlet.

For example, the tip of the O-wing structure of an aircraft or the rotor blade of a helicopter is thin and long, and there is usually a large gold JAr type attached to the attachment part, so no matter which direction the pressure bag is inserted, it will not work. The opening is narrow and there is a matchmaker inside.
AI for 1 pressure bag molding! Although it is difficult to extract the
The remaining materials can be taken out into the valley through such small openings, and the present method is convenient for manufacturing them.

Furthermore, the 710 pressure bag can be made very thin, thus making the pressure bag lighter to stand on and taking advantage of the lightweight advantages of composite materials.

In addition, Atsumachi plastic foam material is not limited to Styrofoam,
Any foam material made of thermoplastic resin such as PVC may be used. These have a tendency to become fluffy when heated and can be cut with a heating wire.

When each part of the styrene violet is separated and joined together with adhesive, the adhesive will squeeze out after heating and shrink, and the shrunken styrene residue will adhere to the inside of the molded composite structure. Sometimes I end up doing it.

In this case, as shown in FIG. 7A, fJ! 42 once wrapped in heat-resistant glass film 68, and then fixed with heat-resistant Chigua 0, for example.
Insert it into the pressurized bag 40 as shown in the figure.

In this way, after the molding, when the heat-resistant plastic film 68 is pulled out from the composite material structure 72 as shown in Figure @ 7c, the Styrofoam residue 70 scattered inside and adhered to the inside is simultaneously removed from the small opening and the size J6 This is very convenient as it will make you fat.

When polystyrene is processed using heating wire, the surface of the polystyrene melts due to the heat, forming a styrofoam. If you cover the D1 pressure bag in this state, the bag may be damaged. In this case as well, these problems can be eliminated by wrapping the styrene mold with a heat-resistant glass film.

FIG. 8 is a horizontal stabilizer for a fixed-reduced aircraft, which includes an angle-of-attack varying bearing mounting portion 80, an opening 82 through which it passes, and a t-! are doing. The wings of such fixed wing aircraft have one or more nine nibs inside. Therefore, when making such a composite structure, a Styrofoam mold is made for each internal space partitioned by the web and placed in a D0 pressure bag. Then, as shown in FIG. 9, Styrofoam molds 84^ and 84B' partitioned by webs and made like nine air barriers are placed in nine pressurized bags 86A and 86B.
1ltl of web 92 on a rigid metal lower die 90 in which uncured composite material sheet 88^ and honeycomb core 88B are laminated.
Placed on iAl and uncured composite material 7-)94^
Rigid gold layered with honeycomb core 94B - 〇 top m96
'I cover it and close it. Then, the pressure inside the molds 90 and 96 is reduced to force the uncured composite material sheet and the two-cam core against the inner surface of the mold and settle them into the positions of the limbs. After that, while applying 710 degrees of pressure to the pressure bags 84^ and 84B,
Upper and lower molds 90 and 96 t7JI] Heat and mold.

As a result, the pressure bags 84 and 84B adhere to the molded composite structure, the non-nicum core, and the web due to their adhesive properties. On the other hand, the shrunken remaining material of @Styrofoam is removed from the opening 82.

According to the present invention, as described above, a structure requiring a large external shape for the internal structure can be manufactured without using expensive jigs.
It has become 9 cases to manufacture it at a small cost. First, the method of the present invention allows deformation of cypress without departing from its spirit, and the structure is simple and easy to form and inexpensive. Figure F shows a hollow composite structure. 3A and 3B are perspective views and longitudinal cross-sectional views of a rotor blade of a helicopter;
Figures 4A to J4D are diagrams showing each step of the method according to the present invention, Figure 5 is a perspective view of a mold for molding the polystyrene foam shown in Figure 4B, and Figures 6 to 6C are diagrams showing each step of the method according to the present invention. , 4th
Figure B shows each step of the method of making each part of the Styrofoam mold with a template and heating wire, and Figures 7 to 7C show some of the other methods according to the present invention. Fig. 8 is a perspective view of the horizontal tail of a fixed wing aircraft, and Fig. 9 shows one step in making a composite structure with a web by the method of the present invention. It is a diagram.

10.18...Mold, 12...Composite material, 14...
・Web, 16...D0 pressure bag, 20...Cavity, 22
...Corner, 24...Wrinkle in the web, 26...
Tear, 30... Rotor blade, 32... Hollow part, 34... Mounting bolt hole, 36... Opening, 40
...7t0 pressure bag, 42...Styrofoam mold, 4
4... Ninth mold of Styrofoam mold, 46.54
... Template, 50... Styrofoam material, 58.
62...Composite material, 60.62...Mold, 68...
・Heat-resistant glass film, 84^, 84B...
Styrofoam mold, 86^, 86El...pressure bag,
92...Web, 90.96...Total sugar 1A Figure 0 Figure 7 0t) Figure 3B Figure 48 Figure 4C Figure 4D Figure 5

Claims (2)

[Claims] (1) Manufacture of a composite material structure by enclosing a molded article made of synthetic resin and reinforcing fibers and an inner mold into a rigid gold IIO that gives a shape of IIO, and heating and molding the inside of the inner mold while pressurizing the inside of the inner mold. In the method, the inner mold is made by bonding a thin adhesive film and inserting into a pressure bag made of a thermoplastic foam material slightly smaller than the required size, The pressurized bag is heated and molded while applying pressure to adhesively bond the pressurized bag to the object to be molded, and after the molding is completed, the remaining material of the contracted thermoplastic foam material in the pressurized bag is removed. A method for manufacturing a composite material structure characterized by: (2) The press mold made of the thermoplastic foam material is wrapped with a heat-resistant film and inserted into the pressure bag, and after the molding is completed, it is removed together with the heat-resistant film Fi and the remaining material of the shrunk thermoplastic foam material. Claim 1 characterized in that
The method for manufacturing a composite material structure described in Section 1. 13) The method for manufacturing a composite structure according to claim 1 or 2, wherein the thermoplastic foam material is foamed steel.