JPH0357869A - Pressure vessel and manufacture thereof - Google Patents

Abstract

PURPOSE:To decrease stress concentration while improving adhesive force between a pressure vessel and a reinforcing member by forming the reinforcing member, adhesively attached to the periphery of an opening part in a dome part of the pressure vessel, with a plurality of reinforcing members and a rubber member adhesively attached to each other. CONSTITUTION:In a pressure vessel 29, a reinforcing member 25 is adhesively attached to the periphery of an opening part in a dome part 28 formed by hardening a continuous fiber impregnated with matrix resin. Here the reinforcing member 25 is formed mainly of a plurality of reinforcing members 21, 24 and a rubber member 23. That is, the first reinforcing member 21, in which fiber- reinforced plastic is used, is formed in a manner, wherein the more approximate to the peripheral end is positioned a part the less its thickness is gradually decreased, and adhesively attached to the periphery of the above described opening part. While the rubber member 23 is adhesively attached to the first reinforcing member 21. Further the boss member 24 as the second reinforcing member is adhesively attached to the rubber member 23 while formed in size smaller than the first reinforcing member 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure vessel manufacturing method for manufacturing a pressure vessel by forming a dome portion using continuous fibers impregnated with a matrix resin, and the pressure vessel. (Conventional technology) Multi-stage rockets are generally used for artificial satellite launches. Figure 12 shows the schematic structure of this multi-stage rocket. In the figure, 1 is the second stage rocket motor, 2 is the third stage rocket motor which is an aboji motor, and 4 is the artificial sanitary. The second stage rocket motor 1 and the third stage rocket motor 2 are connected by an isogrid structure 5. Further, the third stage rocket motor 2 and the artificial graft 4 are connected by a connecting body 6 similar to the isogrid structure. In this way, rocket motors 1 and 2 have a structure in which the front and rear stages are connected, so forces such as weight, axial compression, and bending are applied to the pressure vessels IE and 2E of rocket motors 1 and 2 during launch. In particular, since these forces are concentrated at the openings of the pressure vessels to which the nozzles 1a and 2a are attached, it is necessary to make the openings of the pressure vessels IE and 2E strong. In addition, the pressure vessels 1E and 2E are required to be resistant to pressure and heat when the propellant is combusted, and are also required to be lightweight. To meet these requirements, rocket motor pressure vessels are manufactured using the filament winding method, which involves winding reinforcing fibers impregnated with matrix resin. In this filament winding method, as shown in FIG. 13, carbon fiber or the like impregnated with a matrix resin such as epoxy resin is placed over the mold part 7a of a splittable mandrel 7 consisting of a mold part 7a and a shaft part 7b. The reinforcing fiber 8 is wound by in-brane winding or helical winding to form a dome 9 which becomes the main body of the pressure vessel. After the matrix resin has hardened, the mandrel 7 is disassembled and removed to form a pressure vessel 10 as shown in FIG. 14. but,
With this filament winding method, strength characteristics can be obtained by using continuous reinforcing fibers, but since the reinforcing fibers are manufactured by winding them, the wall thickness is increased only around the opening to reinforce that area. For this reason, as shown in FIG. 13, a boss member 11 separate from the pressure vessel 10 is joined to the side of the mandrel mold part 7a, and reinforced from above the mold part 7a and the boss member 11. The fibers are wrapped around each other. Thereby, the boss member 11 is bonded to the opening and the opening is reinforced. However, in the above pressure vessel, as shown in section Q in FIG.
Since the wall thickness of 0 suddenly became thicker, there was a risk that stress concentration would occur in that area, causing cracks, etc. Therefore, it has been proposed that a rubber member is interposed between the pressure vessel 10 and the boss member 11 to reduce stress concentration. As shown in FIG. 16, this is done by laminating a woven fabric made of carbon fibers, for example, and machining a laminated member 13 that is impregnated with a thermosetting resin as a matrix resin and hardened. Then, the boss member 14, which has a hole 14a formed in the center and an adhesive surface 14b formed at the peripheral end, is carefully fixed, and as shown in FIG.
The rubber member 15 is vulcanized and bonded to the adhesive surface 14b of the mandrel 7, and the rubber member 15 is fitted onto the shaft portion 7b of the mandrel 7 to manufacture the pressure vessel as described above. (Problem to be solved by the invention) However, in the above pressure vessel, the pressure vessel 1
Rubber member 15 vulcanized and bonded between 0 and boss member 14
As a result, there was a problem in that the adhesive force between the boss member 14 and the pressure vessel 10 was weak and the boss member l4 was easily detached from the pressure vessel 10. In addition, a groove is provided in the P portion of the boss member so that the boss member l4 does not come off from the pressure vessel.
There are some devices in which reinforcing fibers are wound around the grooves, but the problem is that it is difficult to wind the reinforcing fibers around the grooves, and the winding process is extremely troublesome. (Purpose) Therefore, this invention was made in view of the above-mentioned problems, and its purpose is to reduce stress concentration, and furthermore, it is possible to reduce the stress concentration between the reinforcing member and the pressure without providing grooves. The object of this invention is to provide a pressure vessel that can increase the adhesive strength with the container, and a method for manufacturing this pressure vessel. (Means for Solving Problem N) In order to achieve the above object, this invention adheres a reinforcing member around the opening of a dome portion formed by hardening continuous fibers impregnated with matrix resin. A pressure vessel, wherein the reinforcing member includes a first annular reinforcing member made of fiber-reinforced plastic that is formed so that its thickness gradually decreases toward the peripheral end and is bonded around the opening; It is characterized by comprising a rubber member bonded to the first reinforcing member, and an annular second reinforcing member bonded to the rubber member and formed to have a smaller diameter than the first reinforcing member. In addition, a mandrel with a shaft coaxially provided on both sides of the dome-shaped IIL type part, and a sheet member made of reinforced fiber plastic with a hole in the center and gradually becoming thinner from the center toward the periphery. By preparing a boss member and an annular raw rubber that accommodate an outer flange having a smaller diameter than this sheet member, and vulcanizing the annular rubber with the annular rubber interposed and crimped between the sheet member and the outer flange, After forming a reinforcing member in which the sheet member and the rubber member are integrally bonded by adhesion of rubber vulcanization, the boss member of the reinforcing member is fitted onto the outer periphery of the shaft portion, and the outer flange is inserted into the dome forming mold. Next, a continuous fiber impregnated with matrix resin is wound around the mold part and the reinforcing member so that a dome opening is formed on the shaft part, and the wound continuous fiber is hardened. The present invention is characterized in that a dome portion is formed by this, and a sheet member of a reinforcing member is adhered around the dome opening. (Function) In this invention, since the first reinforcing member is made of fiber-reinforced plastic, the adhesive strength between the first reinforcing member and the pressure vessel is increased. In addition, since the first reinforcing member is formed so that its thickness gradually decreases toward the peripheral end, the difference in thickness that occurs when it is integrated with the dome portion becomes extremely small. Stress concentration occurring at the peripheral end of the strong member is reduced, and since the second reinforcing member is bonded to the first reinforcing member via the rubber member, the stress concentration is absorbed. Further, since the present invention has the above-mentioned structure, the reinforcing member has the sheet member and the rubber member integrally joined by adhesion of rubber vulcanization. Then, since the sheet material of the reinforcing member is adhered to the dome portion formed by curing the continuous fibers impregnated with matrix resin, its adhesive strength increases. In addition, the sheet member is formed to become gradually thinner from the center toward the periphery, and since a rubber member is interposed between the sheet member and the boss member, the rubber member with a high elastic modulus absorbs stress. , stress concentration is significantly reduced. (Example) Hereinafter, an example of the method for manufacturing a pressure vessel according to the present invention will be described based on the drawings. Figures 1 to 4 show the manufacturing process of reinforcing members for pressure vessels. In the figure, 20 is a sheet material laminated with woven fabrics made of reinforcing fibers such as carbon fiber, aramid fiber, or glass fiber impregnated with a matrix resin such as epoxy resin. This sheet material 20 is set in the female metal fi 22a of the autoclave 22, and steam is blown into the autoclave 22 to heat and pressurize the sheet material 20. As a result, the matrix resin is cured and the sheet material 20 is formed into a predetermined shape. Then, a hole 21a is machined in the center of the sheet material 20 as shown in FIG. The first reinforcing member 21 is processed so that its thickness gradually decreases. Then, on this first reinforcing member 21, a rubber member 23 having a hole 23a in the center and a boss member (second reinforcing member) 24 are stacked on top of each other as shown in FIG. 3 and set in the lower mold K+. Next, the upper mold K2 is pressed and the boss member 2 is attached to the first reinforcing member 21 by hot pressing.
4 is vulcanized and bonded to form the reinforcing member 25 (see Fig. 4). As shown in FIG. 3, the boss member 24 is made by machining a laminated member made by laminating woven fabrics made of, for example, carbon fibers and impregnating and hardening a thermosetting resin as a matrix resin. A hole 24a is formed in the center and an adhesive surface 24b is formed at the peripheral end. Shaft portion 2 of mandrel 26 into which the reinforcing member 25 can be divided
8a as shown in FIG. 5, and also joined to the side of the mold part 26b with the boss member 24 on the inside. Then, as shown in FIG. 6, a continuous reinforcing fiber such as carbon fiber impregnated with plastic such as bisphenol A-based epoxy resin is wound onto the reinforcing member 25 and the mold part 28b by in-brane winding or helical winding to form a dome. Form part 28. After the matrix resin impregnated with these reinforcing fibers is cured, the mandrel 26 is divided and removed to obtain a pressure volume II 29 (see FIG. 7) as shown in FIG. 11. In this case, in order to easily separate the pressure vessel 29 from the mold part 26b of the mandrel 26, the mold part 26b is previously coated with a mold release agent made of sulfur or silicone. The pressure vessel 29 has a dome portion 2 as shown in FIG.
The first reinforcing member 21 is attached to the periphery of the opening 23a on the inside of 8.
The first reinforcing member 21 is constructed by curing a woven fabric layer impregnated with a matrix resin such as epoxy resin, and the dome portion 28 is made of reinforcing fibers impregnated with a matrix resin such as bisphenol A-based epoxy resin. Since the same matrix resin is used, the first reinforcing member 21
It is sufficient that the first reinforcing member 21 and the dome portion 28 are compatible with each other.
The adhesion is strong, and there is no need to provide grooves in the reinforcing member as in the past. In addition, since the thickness of the first reinforcing member 2l gradually decreases toward the peripheral end, the difference in thickness that occurs when it is integrated with the dome portion 28 becomes extremely small. The stress concentration that occurs at the ends is small. Furthermore, a rubber member 2 is provided between the first reinforcing member 21 and the boss 24.
3 is interposed, the stress concentration occurring at the peripheral end of the boss 24 is absorbed by the rubber member 23, so the stress concentration is small.
The relationship between the dome portion 28 and the dome portion 28 will be described from the viewpoint of materials. jll! 1 Various combinations of reinforcing fibers can be used for the reinforcing member 21 and the dome portion 28, but here, we will use carbon fibers with different Young's moduli (Young's modulus E: S760 kgf/mm2), and aramid fibers. (Young's modulus E; 3220kgf/+a+
a, ■Glass fiber (Young's modulus E; 2060 kgf/
mm2) (7) A combination of these three types will be explained. First, considering the case where we focus on reinforcing the dome part A as shown in Fig. 8, the main purpose of interposing the reinforcing member B is to improve the strength against bending as shown by the arrow D near the dome pole C. ．． In other words,
The problem lies in how to reduce the stress generated in the dome part A by using the reinforcing member B. In order to simplify this problem, we decided to model the dome part A and the reinforcing member B as shown in Fig. 9. Here, the thickness t1 of the dome portion A, the thickness t2 of the reinforcing member B, and the respective widths are assumed to be b. Also, the subscript "1" indicates the dome part, and the subscript "2" indicates the dome part.
indicates a reinforcing member, η+ = t+ + t2-η2 Z+=I/ηl, z2=i/η21σ1 ==M/
It can be expressed as Z+, at=M/Z2 − (1). In addition, E is Young's modulus, η is the distance from the centroid, ■ is the moment of inertia of area, Z is the section modulus, and σ is the stress. Then, by solving equation (1) for the case where b = 1 (unit width) and M = 1 (unit moment), the stress generated in the dome part A can be found.
Then, ■ three cases in which the FRP dome part using carbon as continuous fibers is reinforced with FRP using carbon, aramid, and glass as continuous fibers, and ■
The FRP dome part uses aramid as a continuous fiber,
There are three cases in which carbon, aramid, and glass are each reinforced with FRP as continuous fibers;
F using aramid and glass as continuous fibers
Determine the stress generated in the dome part A in total of 9 ways in the three cases reinforced with RP. By the way, it is desirable for the reinforcing member to be as light as possible, so a simple evaluation will show:
(Stress generated in the dome part) X (reinforcing member density) = The smaller the value of X, the better. Therefore, the density ρ of FRP using carbon as continuous fibers is L56, the density ρ of FRP using aramid as continuous fibers is 1.35, and the density ρ of FRP using carbon as continuous fibers is 1.35.
The value of X is determined by setting the density of P as ρ = 1.68, and the relative evaluation value Y is shown in the front work, assuming that the dome part A and reinforcing member B are made of carpon as 1. In this table (■), the thickness t1 of the dome portion 8 is 5 mm, and the thickness t of the reinforcing member B is
2 to 0. 5mm, ltm, 2mm,
The values Y are shown for 3 mm, 4 sails, and 5 mm, respectively. (Left below) Ume l This! l! The value Y shown in r is the smallest when the dome member A is made of glass, the reinforcing member B is carbon, and the thickness of the reinforcing member B is 3 mm and 4 mm. Therefore, a combination of materials that increases the strength against bending is when the dome portion 28 is made of glass and the first reinforcing member 21 is made of carbon. Also, from this surface work, the value Y is smaller than 1 when the dome part A is made of aramid fiber and the reinforcing member B is carbon or aramid fiber, and also when the dome part A is reinforced with glass fiber. This is the case where the member B is made of carbon or aramid fiber. In either case, the Young's modulus E2 of the reinforcing member is greater than the Young's modulus E1 of the dome material.
In other words, as a reinforcing material, the Young's modulus E2 is higher than that of the dome material.
This shows that the reinforcing effect is higher for materials with . By the way, the dome portion 28 and the reinforcing layer (first reinforcing member 21
, the combination of matrix materials used for the boss 24) is most preferably a combination of the same materials, but they may be different. However, since the reinforcing layer is preformed and used, the thermal deformation temperature (glass transition temperature) of the reinforcing layer must be higher than the curing temperature of the dome part 28 so that the reinforcing layer does not undergo thermal deformation during the curing process of the dome part 28. Next, FIG. 11 shows the relationship between the shear stress applied to a portion of the pressure vessel 27 due to stress concentration and that portion. Part 1
■ In the figure, the boss member 24 is directly attached to the dome part 28 as in the conventional case.
In the case where the dome portion 28 is bonded to the dome portion 28, the thickness of the dome portion 28 suddenly becomes thicker at the eight portions, so that the stress concentration occurring at the portion A is large, and the shear stress suddenly increases. (3) is a case where the rubber member 23 is interposed between the dome part 28 and the boss member, and since the stress concentration is absorbed by the rubber member, no sudden increase in shear stress occurs at the entry point, but still Large shear stress occurs. (3) is based on this example, in which the wall thickness of the peripheral edge of the first reinforcing member is thinner near the B part, and the stress concentration by the rubber member is absorbed near the A part, so the shear stress peaks. disappears and becomes almost flat. In other words, the stress concentration near part A is significantly reduced. (Effects) As explained above, according to the present invention, it is possible to increase the adhesive strength between the reinforcing member and the pressure vessel without providing a groove, and it is also possible to significantly reduce stress concentration.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a certain shape of an autoclave according to the present invention, FIG. 2 is an explanatory diagram of the first reinforcing member, and FIG. 3 is an explanatory diagram showing the overlapping state of the first reinforcing member, the rubber member, and the boss. Fourth
Figure 5 is an explanatory diagram of the reinforcing member, Figure 5 is an explanatory diagram of attaching the reinforcing member to the mantrell, Figure 6 is an explanatory diagram of forming the dome section, Figure 7 is an enlarged partial cross-sectional view of the pressure vessel, and Figure 8 is the dome. Fig. 9 is an explanatory drawing showing the dome model, Fig. 10 is an explanatory drawing showing the thickness of the dome part and reinforcing member, and Fig. 11 is an illustration of shear stress and pressure vessel. Figure 12 is an explanatory diagram of a rocket, Figure 13 is an explanatory diagram of manufacturing a pressure vessel by the filament winding method, and Figure 14 is a cross-sectional view of a conventional pressure vessel. , FIG. 15 is a partially enlarged sectional view of a conventional pressure vessel, and FIG. 16 is an explanatory diagram of a laminated member.
FIG. 17 is an explanatory diagram of a boss member, and FIG. 18 is an explanatory diagram of a rubber member bonded to the boss member by vulcanization. 1... First reinforcing member 1a... Hole 3... Rubber member 4... Boss member (second reinforcing member) 5... Reinforcing member 6... Mandrel 2nd day 6a... Shaft part 6b...Mold part 8...Dome part 9...Pressure vessel 1 Figure 2 Figure 21 Figure 3\K+ Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure A 10 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 1 et al.

Claims (2)

[Claims] (1) A pressure vessel in which a reinforcing member is adhered around the opening of a dome portion formed by curing continuous fibers impregnated with a matrix resin, wherein the reinforcing member has a wall thickness that gradually decreases toward the peripheral edge. a first annular reinforcing member made of fiber-reinforced plastic and bonded around the opening; a rubber member bonded to the first reinforcing member; and a rubber member bonded to the rubber member and bonded to the opening. and a second annular reinforcing member having a smaller diameter than the first reinforcing member. (2) a mandrel having a shaft coaxially provided on both sides of the dome-forming mold part; a sheet member made of reinforced fiber plastic; having a hole in the center and gradually becoming thinner from the center toward the periphery; By preparing a boss member and an annular raw rubber having an outer flange with a diameter smaller than that of the sheet member, and vulcanizing the annular rubber with the annular rubber interposed between the sheet member and the outer flange, the sheet member is After forming a reinforcing member in which the and rubber members are integrally joined by adhesion of rubber vulcanization, the boss member of the reinforcing member is fitted onto the outer periphery of the shaft portion, and the outer flange is attached to the dome forming mold portion. Then, a continuous fiber impregnated with a matrix resin is wound on the mold part and the reinforcing member so that a dome opening is formed in the shaft part, and the wound continuous fiber is cured. A method of manufacturing a pressure vessel, comprising: forming a dome portion, and adhering a sheet member of a reinforcing member around the dome opening.