阅读说明：本技术 复合材料成形夹具及复合材料成形方法 (Composite material forming jig and composite material forming method ) 是由 长田保 于 2018-04-02 设计创作，主要内容包括：实施方式的复合材料成形夹具(3)能够简单地成形具有中空结构的复合材料结构体O(O1,O2),是向内部引导空气而使用的。该复合材料成形夹具3包括具有挠性的筒状体5和局部加强上述筒状体5的强度的至少一个刚体的板状体6(6A,6B)。另外,实施方式的复合材料成形方法能够简单地成形具有中空结构的复合材料结构体O(O1,O2),使用上述的复合材料成形夹具3制作复合材料结构体O(O1,O2)。(The composite material forming jig (3) of the embodiment can easily form a composite material structure O (O1, O2) having a hollow structure, and is used by introducing air into the inside. The composite material forming jig 3 includes a flexible cylindrical body 5 and at least one rigid plate-like body 6(6A, 6B) that partially reinforces the strength of the cylindrical body 5. In addition, the composite material molding method of the embodiment can easily mold the composite material structure O (O1, O2) having a hollow structure, and produce the composite material structure O (O1, O2) using the composite material molding jig 3 described above.)

1. A composite material forming jig used by introducing air to the inside, the composite material forming jig comprising:

a cylindrical body having flexibility; and

at least one rigid plate-like body which locally reinforces the strength of the tubular body.

2. The composite forming jig of claim 1,

the plurality of plate-like bodies are arranged with a gap therebetween in a direction perpendicular to the longitudinal direction of the cylindrical body so that the cylindrical body can be locally deformed in the cross section of the cylindrical body, and the deformation of the cylindrical body in a plane parallel to the longitudinal direction of the cylindrical body is suppressed.

3. The composite forming jig of claim 1 or 2,

in order to enable a composite material structure to be supported from the inside of an elongated structure in curing, the composite material structure being obtained by forming the elongated structure having a hat-shaped cross section on a panel, the composite material structure is provided with at least a first plate-shaped body which reinforces the strength of a portion of the tubular body which supports a lid portion of the elongated structure from the inside, and two second plate-shaped bodies which reinforce the strength of portions of the tubular body which support web plates at two locations of the elongated structure from the inside.

4. The composite forming jig of claim 3,

the plate-like body is not provided on the panel side.

5. The composite forming jig of claim 3,

the plurality of plate-like bodies are arranged on the panel side so as not to overlap each other.

6. The composite material forming jig according to any one of claims 1 to 5,

the plate-like body is integrally fitted into the cylindrical body.

7. The composite material forming jig according to any one of claims 1 to 5,

embedding a portion of the plate-like body into the cylindrical body.

8. The composite material forming jig according to any one of claims 1 to 5,

and attaching the plate-shaped body to the inner surface of the cylindrical body.

9. The composite material forming jig according to any one of claims 1 to 8,

the cylindrical body is formed of an elastic body, and the plate-like body is formed of a composite material made of a fiber-reinforced resin.

10. A method for forming a composite material, wherein,

a composite material structure produced by using the composite material forming jig according to any one of claims 1 to 9.

11. A method for forming a composite material, wherein,

a hollow composite material structure having a two-dimensional closed curved surface is manufactured by using the composite material forming jig according to claim 1 or 2.

12. A composite material forming method according to claim 10 or 11, wherein there is:

laminating a sheet-like prepreg or a sheet-like fiber for a panel on a molding die;

placing the composite material molding jig on which the sheet-like prepreg or the sheet-like fiber for the reinforcing member of the panel is laminated, on the laminated sheet-like prepreg or the laminated sheet-like fiber for the panel;

a step of packaging the laminated sheet-like prepreg or the laminated sheet-like fiber for the panel and the reinforcing member by covering the sheet-like prepreg or the sheet-like fiber with a packaging film so that the inside of the composite material molding jig is not hermetically sealed, and by reducing the pressure in a region covered with the packaging film;

a step of producing the composite structure by heat-curing the packaged uncured thermosetting resin reinforced with sheet-like fibers; and

and a step of removing the composite material forming jig from the composite material structure after the heat curing.

13. The composite forming method of claim 12,

comprises the following steps:

placing the composite material molding jig on the sheet-shaped prepreg or the sheet-shaped fiber in a state where a positioning member for restraining a rigid body of the composite material molding jig from flexing is inserted into the composite material molding jig,

withdrawing the positioning member from the composite forming jig after the wrapping or after the heat curing.

14. The composite material forming method according to claim 12 or 13,

also comprises the following steps:

laminating the sheet-like fibers for the panel to the molding die, and laminating the sheet-like fibers for the reinforcing member to the composite material molding jig,

the uncured thermosetting resin is impregnated into the laminated sheet-like fibers by injecting the uncured thermosetting resin into the region covered with the packaging film.

15. The composite forming method of claim 14,

the uncured thermosetting resin is injected from a position where at least the sheet-like fibers for the reinforcing member are laminated.

Technical Field

Embodiments of the present invention relate to a composite material molding jig and a composite material molding method.

Background

Composite materials such as Glass Fiber Reinforced Plastics (GFRP) and Carbon Fiber Reinforced Plastics (CFRP) using Fiber Reinforced resin have been used as materials for structures such as aircraft structures.

As a method for molding a composite material, there are known: a method in which prepregs (プリプレグ) in which sheet-like fibers are impregnated with an uncured thermosetting resin are laminated, the laminated body of the prepregs is prepared into a shape after molding, and then the prepreg is evacuated and cured by heating; after the sheet-like fibers are laminated in accordance with the shape of the molded composite material, a Resin Transfer Molding (RTM) method is performed in which a thermosetting Resin is impregnated and cured by heating while vacuum is drawn. The prepreg is heat cured using an oven or autoclave apparatus. The operation of preparing a prepreg shape is called shaping for distinguishing it from the molding of a composite material by heat curing.

As a jig for forming a prepreg or a fiber by laminating, various jigs such as a rigid molding die and a bag are designed. As a specific example, a shape retaining tool capable of performing vacuum-pumping by connecting GFRP panels with silicone rubber sheets has been proposed as a jig for forming a web of a cross member in a wing structure of an aircraft having the cross member (support) attached to an outer panel (panel) (see, for example, patent document 1). As a vacuum bag for performing vacuum evacuation, a vacuum bag in which a rigid frame is sealed in a flexible diaphragm so as to be reusable has been proposed (for example, see patent document 2).

On the other hand, as a method of forming a frame of a composite material used for an aircraft part or the like, the following methods have also been proposed: a frame is formed by an RTM method using an outer mold made of metal, an inner mold made of synthetic resin or rubber, and a tubular core formed of flexible synthetic resin such as rubber (see, for example, patent document 3).

In a wing structure and a fuselage structure of an aircraft, a composite structure in which a reinforcing member having a long structure is attached to a panel is used. Examples of the reinforcing member of the panel include ribs (ribs) and stringers (stringers) in addition to the support. In recent years, composite material structures having reinforcing members attached to panels have been manufactured by co-curing molding without heat curing of each component in order to suppress an increase in manufacturing cost and manufacturing time associated with the assembly work of the components. The co-curing molding is a molding method in which the reinforcing member and the face plate are simultaneously heat-cured.

When a composite material structure in which a reinforcing member is attached to a panel is formed by co-curing molding, a laminate of prepregs for the reinforcing member and a laminate of prepregs for the panel are separately produced, and the laminate of prepregs is assembled and then cured by heating, thereby producing the composite material structure. Alternatively, an integrated prepreg laminate having a reinforcing member formed on a face sheet may be prepared and cured by heating.

In the case where the cross section of the reinforcing member attached to the panel is of a hat type, the composite material structure has a hollow structure. Therefore, it is necessary to form the fiber impregnated with the uncured resin into a hollow structure. Therefore, various molding jigs are used for forming a hollow structure of the fiber impregnated with the uncured resin, and then performing vacuum-pumping and heat curing.

Conventional methods for forming a composite material structure for an aircraft in which a reinforcing member having a hat-shaped cross section is attached to a panel are roughly classified into: an OML jig system in which a rigid mold is provided on the outer mold line side of a panel, which is the surface of a panel on which a reinforcing member is not provided, and the inner mold line side of a panel, which is the surface of a panel on which a reinforcing member is provided, is wrapped (バギング) to apply atmospheric pressure; on the other hand, an IML jig system is used in which a rigid mold is provided on the IML side of the panel, and the OML side of the panel is wrapped and subjected to atmospheric pressure.

As a specific example of a method of forming a composite material structure having a hollow structure by an IML jig method, a method of disposing a bag inside a reinforcing member, which is a space between a resin for a panel and a resin for a reinforcing member, is known (for example, see patent document 4). The bladder is a bag made of an elastic body, and is one of inflatable mandrels used by injecting air. In the IML jig system, in order to maintain accuracy, it is also necessary to provide a rigid plate on the OML side of the panel and then package the panel.

On the other hand, as a specific example of a method of forming a composite material structure having a hollow structure by an OML jig, there is a method of providing a solid mandrel as a core jig inside a reinforcing member, which is a space between a resin for a panel and a resin for a reinforcing member (for example, see patent document 5). In addition, there is proposed a method in the OML jig method: a hollow internal member made of a thermosetting resin is disposed inside the reinforcing member, and the internal member and the reinforcing member are integrated by heat curing (see, for example, patent document 6).

Disclosure of Invention

Problems to be solved by the invention

However, in the case of the IML jig method, a forming die is required according to the shape of the reinforcing member. Therefore, there is a problem that a forming die having a complicated structure needs to be manufactured. Further, a prepreg for a panel is laminated on the bag. Therefore, it may be difficult to keep the panel flat. In other words, the elasticity and strength of the bag need to be designed so as to support the laminate of the prepreg for the panel. Further, since the uncured resin is sandwiched between the upper and lower rigid molding dies, there is a problem that the pressure is not uniform even if atmospheric pressure is applied.

On the other hand, in the case of the OML jig system in which a mandrel is provided as a core jig inside a reinforcing member, it is necessary to extract the mandrel of a rigid body after curing the composite material. Thus, the shape of the composite material is defined as the shape of the extractable mandrel. In addition, the weight of the spindle is also limited to the extractable weight. In particular, when a heavy mandrel is provided, the mandrel extraction operation requires time and labor.

On the other hand, in the case of the OML jig system in which a hollow internal member is disposed inside a reinforcing member and integrated with the reinforcing member, a cover plate (カウルプレート) as a rigid body forming mold needs to be provided outside the reinforcing member.

Further, even if the bladder is disposed inside the reinforcing member instead of the hollow inner member, the bladder itself does not have a function of retaining the shape, and therefore, the bladder is deformed from an ideal shape during the heat curing of the composite material. Therefore, even when the bladder is disposed inside the reinforcing member, it is necessary to provide a cover plate of a rigid mold outside the reinforcing member. As a result, not only the structure of the jig is complicated, but also the uncured resin is sandwiched by the upper limit rigid body molding die as in the IML jig system, and therefore, there is a problem that the pressure is not uniform even if atmospheric pressure is applied.

Therefore, an object of the present invention is to enable a composite material structure having a hollow structure to be easily molded.

Means for solving the problems

The composite material forming jig according to an embodiment of the present invention is used by introducing air into an interior thereof, and includes: a cylindrical body having flexibility; at least one rigid plate-like body which locally reinforces the strength of the tubular body.

In the composite material molding method according to the embodiment of the present invention, a composite material structure is produced by using the composite material molding jig.

Drawings

Fig. 1 is a cross section showing the structure of a molding jig unit including a reinforcing bag (reinforcing bar りブラダバッグ) as a composite molding jig according to a first embodiment of the present invention.

Fig. 2 is a perspective view showing the structure of an end portion of the reinforced type bladder shown in fig. 1.

Fig. 3 is a longitudinal sectional view illustrating a sealing method of an end of the reinforced type bladder shown in fig. 1.

Fig. 4 is a cross-sectional view showing an example of a composite structure configured by attaching corrugated stringers, which can be formed by using the reinforced-type bladder shown in fig. 1 as a core clip, to a panel.

Fig. 5 is a cross-sectional view showing an example of a composite material structure having a structure in which an upper side panel and a lower side panel, which can be formed by using the reinforced type bladder shown in fig. 1 as a core jig, are connected by a plurality of stringers.

Fig. 6 is a flowchart showing a first example of a method for molding a composite material structure using the molding jig unit shown in fig. 1.

Fig. 7 is a flowchart showing a second example of a method of molding a composite material structure using the molding jig unit shown in fig. 1.

Fig. 8 is a diagram showing a conventional OML jig type composite material molding method for molding a composite material structure having a hat-shaped cross section by using a mandrel as a core jig.

Fig. 9 is a diagram showing a conventional composite material molding method of the IML jig method in which a composite material structure having a hat-shaped cross section is molded using upper and lower molding dies and a general bag.

Fig. 10 is a diagram showing a conventional OML jig type composite material molding method for molding a composite material structure having a hat-shaped cross section by using upper and lower molding dies and a general bag.

Fig. 11 is a cross-sectional view showing the structure of a reinforced type bladder as a composite material molding jig according to a second embodiment of the present invention.

Fig. 12 is a cross section showing the structure of a reinforced type bladder as a composite material molding jig according to a third embodiment of the present invention.

Fig. 13 is a cross section showing the structure of a reinforced type bladder as a composite material molding jig according to a fourth embodiment of the present invention.

Detailed description of the preferred embodiments

A composite material molding jig and a composite material molding method according to an embodiment of the present invention will be described with reference to the drawings.

(first embodiment)

(Structure and function of composite Material Molding jig)

Fig. 1 is a cross section showing a structure of a molding jig unit including a reinforced type bladder as a composite material molding jig according to a first embodiment of the present invention.

The molding jig unit 1 is a jig for molding a hollow composite material structure O having a two-dimensional closed curved surface. That is, the molding jig unit 1 is a jig for laminating prepregs before curing, which are obtained by impregnating a sheet-like fiber bundle with a thermosetting resin, shaping the laminated prepregs, and heating and curing the laminated prepreg.

Further, the sheet-like fibers may be laminated and then impregnated with the thermosetting resin. In this case, sheet-shaped fibers are laminated using the molding jig unit 1 instead of sheet-shaped prepregs. The method of molding a composite material impregnated with a resin after stacking fibers is referred to as the RTM method as described above. Among RTM methods, a method of impregnating fibers with a Resin under vacuum pressure is called vartm (vacumized Resin Transfer molding) method.

The molding jig unit 1 may be used for molding a composite material by a hybrid molding method using both lamination of prepregs and an RTM method. The hybrid molding method is a composite material molding method in which sheet-like fibers are laminated on a laminate of prepregs, and the laminated sheet-like fibers are impregnated with a resin and then heat cured. Therefore, when the molding jig unit 1 is used for molding a composite material by the hybrid molding method, both a sheet-shaped prepreg and a sheet-shaped fiber are laminated.

As a method of heat-curing the composite material, any method can be employed. A typical heat curing method of the composite material includes a method of feeding the composite material before curing into an autoclave molding apparatus, evacuating the composite material, and heat curing the composite material under pressure. On the other hand, various Out-of-autoclave (OoA: Out of autoclave) molding methods are known for molding a composite material without using an autoclave molding apparatus. As a specific example, a method of curing a composite material by heating in an oven is known. Therefore, the molding jig unit 1 provided with the composite material before curing and after shaping can be fed into a desired apparatus corresponding to the heat curing method of the composite material.

As an example of a material constituting the composite structure O, a composite material using a carbon fiber or glass fiber reinforced resin such as CFRP or GFRP is typical. As an example of the composite structure O having a hollow structure, there is a composite structure O in which a long structure O2 having a hat-shaped cross section is formed on a panel O1 as illustrated in fig. 1. The composite material structure O having such a structure is mainly used as a wing structure and a fuselage structure of an aircraft. As an example of the long structure O2 having a hat-shaped cross section, a reinforcing member having a long structure such as a rib or a side member can be given.

When the molding jig unit 1 is used, co-curing molding can be performed in which the reinforcing member is laminated with the sheet-like prepreg or the sheet-like fiber for the panel O1, the reinforcing member is shaped with the uncured resin for the panel O1, and the reinforcing member and the panel O1 are simultaneously heat-cured. That is, the reinforcing member and the panel O1 can be assembled in an uncured state, and then packaged and simultaneously heat-cured.

For this purpose, the molding jig unit 1 is configured by a molding die 2, a reinforcing type bag 3, and a packaging film 4.

The forming mold 2 is a rigid body mold supporting the OML side of the panel O1. The OML-side surface of the panel O1 is not limited to a flat surface, and may be a curved surface with a small curvature. Therefore, the surface of the forming die 2 has a substantially flat shape matching the surface of the OML side of the formed panel O1. The molding die 2 is used for laminating sheet-like prepregs or fibers for the panel O1, shaping the OML side of the uncured resin for the panel O1, and supporting the panel O1 from the OML side during heat curing. The molding jig unit 1 is a jig unit for supporting the OML side of the panel O1 by the molding die 2, and can be said to be a jig unit for the OML jig system.

The reinforced bladder 3 is an inflatable mandrel that directs air inwardly and acts as part of the core clamp. That is, the reinforcing type bladder 3 is disposed inside the composite material structure O having a hollow structure and used. Therefore, the reinforced bladder 3 has a shape that fits inside the composite structure O having a hollow structure in an expanded state.

The reinforced bladder 3 is composed of a flexible cylindrical body 5 and at least one rigid plate-like body 6 which is integrally fitted into the cylindrical body 5 in order to partially reinforce the strength of the cylindrical body 5. In the example shown in fig. 1, 3 plate-like bodies 6 are inserted into the tubular body 5 in different directions with a gap therebetween in a direction perpendicular to the longitudinal direction of the tubular body 5.

The cylindrical body 5 is made of the same material as that of the conventional pouch. Specifically, the tubular body 5 may be formed of an elastic body. The elastic body is a polymer material having rubber-like elasticity. On the other hand, the plate-like body 6 may be made of a metal having sufficient mechanical strength or a composite material such as CFRP, and functions as a rigid body. In particular, if the plate-like body 6 is made of a composite material, it is possible to reduce the increase in weight of the reinforced bladder 3 associated with the installation of the plate-like body 6 while securing the strength required for the plate-like body 6. The cylindrical body 5 having the plate-like body 6 embedded therein can be manufactured by arranging the plate-like body 6 at an appropriate position, and vulcanizing and molding the elastic body.

When the plurality of plate-like bodies 6 are fitted into the cylindrical body 5, the plurality of plate-like bodies 6 can be arranged with a gap therebetween in a direction perpendicular to the longitudinal direction of the cylindrical body 5. This allows the cylindrical body 5 to be locally deformed in the cross section of the cylindrical body 5, while suppressing deformation of the cylindrical body 5 in a plane parallel to the longitudinal direction of the cylindrical body 5. In other words, the cross-sectional shape of the tubular body 5 can be deformed in a definite manner, and the tubular body 5 can be provided with rigidity on a plane parallel to the longitudinal direction of the tubular body 5.

As shown in fig. 1, when a composite material structure O in which a long structure O2 having a hat-shaped cross section is formed on a panel O1 is a molding target, the reinforcing type bag 3 is disposed inside a long structure O2 having a hat-shaped cross section and is used as a core jig. Therefore, the cross section of the tubular body 5 is also shaped to fit inside the hat-shaped elongated structure O2, specifically, an isosceles trapezoid with 4 vertexes chamfered with R.

The long structure O2 having a hat-shaped cross section has a structure in which the web O4 at two locations of the flat plate is closed by the flat plate-shaped lid O3. Therefore, when the composite structure O having the long structure O2 with the hat-shaped cross section formed on the panel O1 is to be molded, the first plate-like body 6A and the two second plate-like bodies 6B can be fitted into the tubular body 5 as illustrated in fig. 1, and the composite structure O being cured can be supported from the inside of the long structure O2.

The first plate-like body 6A is a plate-like body 6 for reinforcing the strength of the portion of the tubular body 5 that supports the lid portion O3 of the elongated structure O2 from the inside. On the other hand, the two second plate-like bodies 6B are plate-like bodies 6 for reinforcing the strength of the portions of the tubular body 5 that support the web O4 at the two portions of the elongated structure O2 from the inside. Therefore, the first plate-like body 6A is disposed at a position corresponding to the upper base of the isosceles trapezoid subjected to the R-chamfering. On the other hand, the two second plate-like bodies 6B are disposed at positions corresponding to the two waists of the R-chamfered isosceles trapezoid, respectively.

On the other hand, the plate-like body 6 is not provided on the portion of the cylindrical body 5 that is bonded to the R-chamfer of the long structure O2 from the inside and on the panel O1 side of the cylindrical body 5. That is, the portion of the reinforced bag 3 that supports the R-chamfer of the long structure O2 from the inside and the portion of the reinforced bag 3 on the panel O1 side are not reinforced by the plate-like body 6 and are made of only an elastic body.

Therefore, the portion of the reinforcing bladder 3 where the plate-like body 6 is not provided can follow the shape change of the composite material structure O during heat curing due to the stretchability of the elastic body. That is, the reinforcing bag 3 can be deformed in accordance with the deformation of the long structure O2 during heat curing. Further, since the plate-like body 6 is not inserted into the portion on the panel O1 side, the reinforcing bag 3 can be folded inward and easily pulled out from the inside of the long structure O2 after the composite material structure O is cured by heating.

When the reinforced type bladder 3 having such a structure is used as a core jig, the shape of the elongated structure O2 can be maintained throughout before and after heat curing. That is, the fiber impregnated with the uncured resin can be shaped into the shape of the long structure O2 by the reinforcing type bag 3 reinforced by the plate-like body 6 without using a rigid body molding die. Further, the shaped uncured resin can then be cured by heating while maintaining the shape.

The packaging film 4 is a film for packaging the composite material structure O before heat curing. The packaging film 4 is attached to the molding die 2 and the cylindrical body 5 of the reinforced bag 3 by the sealant 7. The region covered with the packaging film 4 is depressurized by a vacuum apparatus 8 equipped with a vacuum pump.

Fig. 2 is a perspective view showing the structure of an end of the reinforced type bladder 3 shown in fig. 1.

As shown in fig. 2, the length of the reinforced type pockets 3 is determined to be longer than the length of the long strip structure O2. In addition, the length of the reinforced type pocket 3 is determined to be a length protruding from the rim of the panel O1. This is because the inside of the reinforcing bag 3 can be opened to the outside, and the packaging film 4 can be attached to the reinforcing bag 3 by the sealant 7 on the outside of the uncured resin.

The sides of the reinforced bladder 3 do not necessarily need to be occluded. This is because it is desirable to guide air for heating into the reinforcing bladder 3 during the heat curing of the composite material structure O. Further, at the time of positioning the reinforced type bladder 3, it is desirable to insert the rigid positioning member 9 into the reinforced type bladder 3 in order to suppress the deflection of the reinforced type bladder 3 in the longitudinal direction.

However, in order to obtain strength, the side surface of the reinforced bladder 3 may be closed and a through hole for guiding air may be provided. Further, the side surface of the reinforced bag 3 may be closed by an openable cover.

Fig. 3 is a longitudinal sectional view illustrating a sealing method of an end of the reinforced type bladder 3 shown in fig. 1.

As shown in fig. 3, a portion of the packaging film 4 covering the long structure O2 before curing can be attached to the reinforcing bag 3 by the sealant 7. Further, the portion of the packaging film 4 covering the panel O1 before curing can be attached to the mold 2 by the sealant 7. Further, the gap formed between the reinforcing bag 3 and the molding die 2 and corresponding to the thickness of the panel O1 can be closed by the sealant 7.

This makes it possible to seal the region covered with the packaging film 4 and to perform evacuation by the vacuum apparatus 8. That is, by discharging air from the region covered with the packaging film 4, atmospheric pressure can be applied to the resin before and after curing.

Fig. 1 shows an example of a case where the composite material structure O formed on the panel O1 with the long structure O2 having a hat-shaped cross section is a target for molding, but the reinforcing bag 3 can be used for various applications of molding processing for composite material structures having a hollow structure formed by a two-dimensional closed curved surface.

Fig. 4 is a cross-sectional view showing an example of a composite structure O7 configured by attaching corrugated stringers O5, which can be formed by using the reinforced bag 3 shown in fig. 1 as a core clip, to a panel O6.

As shown in fig. 4, a composite material structure O7 configured by attaching corrugated stringers O5 having a corrugated structure obtained by coupling a plurality of reinforcing members having hat-shaped cross sections to a panel O6 can be formed using a plurality of reinforcing bags 3. That is, the composite material structure O7 can be heated and cured in a state where the reinforcing bags 3 are placed in each of the plurality of spaces surrounded by the closed curved surfaces formed between the corrugated stringers O5 and the panel O6.

Fig. 5 is a cross-sectional view showing an example of a composite material structure O11, and the composite material structure O11 has a structure in which an upper side panel O8 and a lower side panel O9, which can be formed by using the reinforced type bag 3 shown in fig. 1 as a core jig, are joined by a plurality of stringers O10.

As shown in fig. 5, a composite structure O11 having a structure in which an upper side panel O8 and a lower side panel O9 are connected by a plurality of stringers O10 can be formed using a plurality of reinforced bags 3. That is, the composite structure O11 can be heat-cured in a state where the reinforcing bladder 3 is placed in a space surrounded by a closed curved surface formed between the upper side panel O8, the lower side panel O9, and the two adjacent side members O10. Further, the shape of the cross section of the side member O10 is not limited to the I-shape, but is arbitrary.

(method of Forming composite Material Using composite Material Forming jig)

Next, a composite material molding method for producing a hollow composite material structure O having a two-dimensional closed curved surface by using the molding jig unit 1 including the reinforcing type bag 3 will be described.

Fig. 6 is a flowchart showing a first example of a method of molding the composite material structure O using the molding jig unit 1 shown in fig. 1.

First, in step S1, a sheet-like prepreg P1 for the panel O1 is stacked on the molding die 2. On the other hand, in step S2, a sheet-like prepreg P2 for the long structure O2 as a reinforcing member of the panel O1 is laminated on the reinforced bag 3. The prepreg P1 for the panel O1 and the prepreg P2 for the long structure O2 can be laminated on the molding die 2 and the reinforcing bag 3, respectively, by an automatic laminating device. Alternatively, the worker may manually stack the prepreg P1 for the panel O1 and the prepreg P2 for the long structure O2.

The reinforced bag 3 in which the prepreg P2 for the long structure O2 is laminated is locally reinforced by the plate-like body 6. Specifically, the strength of the portion of the tubular body 5 that supports the lid portion O3 of the elongated structure O2 from inside is reinforced by the first plate-like body 6A. Further, the strength of the portions of the tubular body 5 that support the web O4 at two locations of the long structure O2 from the inside is reinforced by the two second plate-like bodies 6B. Therefore, by simply laminating the prepreg P2 for the long structure O2 on the reinforced bag 3, a laminate of the prepregs P2 for the long structure O2 can be formed in accordance with the shape of the long structure O2.

However, as described later, a laminate of prepregs P2 for the long structure O2 may be formed by using a rigid jig such as the positioning member 9 in combination.

Next, in step S3, the reinforcing bag 3 in which the sheet-like prepreg P2 for the long structure O2 is laminated is placed on the sheet-like prepreg P1 for the laminated panel O1.

Further, after the reinforcing bag 3 is placed on the sheet-like prepreg P1 for the panel O1, the sheet-like prepreg P2 for the long structure O2 may be laminated on the reinforcing bag 3. However, if the prepreg P1 for the panel O1 and the prepreg P2 for the long structure O2 are stacked and assembled, the working time is shortened.

In the case where the prepreg P1 for the panel O1 and the prepreg P2 for the long structure O2 are laminated separately, the prepreg P2 for the long structure O2 may be laminated on a rigid mold for the long structure O2 and shaped, and then the laminate of the prepreg P2 for the long structure O2 may be placed on the reinforcing bag 3. In other words, the preform (uncured composite material) for the long structure O2 may be shaped by using a jig for another rigid body without using the reinforcing bag 3. In this case, since the preform for the long structure O2 is shaped by a rigid jig, a high-quality preform can be manufactured.

The reinforced type bladder 3 has a long strip structure and has flexibility. Therefore, when the length of the reinforced type bladder 3 is long, even if the reinforced type bladder 3 is reinforced by the plate-like body 6, the reinforced type bladder 3 is bent when being conveyed by a lifter or the like. In particular, it is difficult to convey and position the reinforcing bag 3 in a state in which the prepreg P2 for the long structure O2 is laminated, while maintaining the shape of the laminated body of the prepreg P2 for the long structure O2.

Therefore, from the viewpoint of placing the reinforcing pockets 3 at more precise positions, it is preferable to place the reinforcing pockets 3 on the sheet-like prepreg P1 with the positioning members 9 of the rigid bodies for suppressing the deflection of the reinforcing pockets 3 inserted into the reinforcing pockets 3. The positioning member 9 may be inserted into the reinforcing bag 3 before the prepreg P2 for the long structure O2 is laminated, or may be inserted into the reinforcing bag 3 after the prepreg P2 for the long structure O2 is laminated.

If the positioning member 9 is inserted into the reinforced bag 3 before the prepreg P2 for the long structure O2 is laminated, the rigidity of the reinforced bag 3 can be further ensured when the prepreg P2 for the long structure O2 is laminated. That is, the rigidity of the reinforced bladder 3 can be maintained to the same extent as that of the rigid body. Therefore, when the preform for the reinforced bag 3 shaped long structure O2 is used, the preform for the long structure O2 can be produced with the same quality as when the preform for the rigid mold shaped long structure O2 is used.

The shape of the positioning member 9 is preferably the same as the shape of the space formed inside the reinforced bag 3 so that the reinforced bag 3 can be appropriately pulled out from the reinforced bag 3 while suppressing the deflection of the reinforced bag 3. Therefore, the positioning member 9 has a long structure and has an isosceles trapezoid shape with R-chamfered corners at 4 vertexes. In order to easily pull out the positioning member 9 from the reinforced bladder 3, it is appropriate to provide a gap in the outer surface size of the positioning member 9 with respect to the inner surface size of the reinforced bladder 3.

When the assembly of the laminate of the prepreg P1 for the panel O1 and the laminate of the prepreg P2 for the long structure O2 is completed, packaging is performed in step S4. Specifically, the sheet-shaped prepreg P1 for the laminated panel O1 and the sheet-shaped prepreg P2 for the long structure O2 are covered with the packaging film 4. However, the laminate of the prepreg P1 for the panel O1 and the laminate of the prepreg P2 for the long structure O2 are covered with the packaging film 4 so that the interior of the reinforced bag 3 is not sealed and is open to the outside.

Then, the vacuum device 8 is driven, and air is discharged from the area covered by the packaging film 4. That is, the area covered with the packaging film 4 is depressurized by the vacuum apparatus 8. Thereby, a differential pressure between the atmospheric pressure applied from the outside of the packaging film 4 and the vacuum pressure in the region covered with the packaging film 4 is applied to the region covered with the packaging film 4.

At this time, the inside of the reinforced bag 3 is not sealed with the packaging film 4, and therefore, the atmospheric pressure is reached. Therefore, the atmospheric pressure applied from the outside of the reinforced bag 3 through the laminated body of the prepreg P2 for the packaging film 4 and the long structure O2 is balanced with the atmospheric pressure applied to the reinforced bag 3 from the inside of the reinforced bag 3. The flat portions of the reinforced bag 3 bonded to the lid portion O3 and the web O4 of the uncured elongated structure O2 are reinforced by the first plate-like member 6A and the second plate-like member 6B, respectively. As a result, the shape of the laminate of the prepregs P2 for the long structure O2 can be held by the reinforcing bag 3 in accordance with the shape of the long structure O2 after molding before and after packaging.

Next, in step S5, the packaged laminate of the prepreg P1 for the panel O1 and the laminate of the prepreg P2 for the long structure O2, that is, the uncured thermosetting resin reinforced with the sheet-like fibers, are cured by heating.

For this purpose, the packaged laminate of the prepreg P1 for the panel O1 and the laminate of the prepreg P2 for the long structure O2 are fed into an oven or autoclave apparatus together with the molding die 2 and the reinforcing bag 3. Then, the composite structure O obtained by mounting the long structure O2 on the panel O1 was co-cured and molded by heating the laminate of the prepreg P1 for the panel O1 and the laminate of the prepreg P2 for the long structure O2 under pressure in an oven or an autoclave apparatus.

When the composite material structure O is heat-cured, the composite material structure O is deformed very little with heat-curing. On the other hand, since the material of the tubular body 5 constituting the reinforced bladder 3 is an elastic body, the reinforced bladder 3 has flexibility in addition to the flat portions on the lid portion O3 side and the web O4 side reinforced by the first plate-like body 6A and the second plate-like body 6B, respectively. Therefore, even if the composite material structure O including the elongated structure O2 is deformed by heat curing, the reinforcing pockets 3 can be attached to the inner surface side of the elongated structure O2. As a result, the composite structure O in which the long structure O2 having a hat-shaped cross section is attached to the panel O1 can be produced with good quality.

Next, in step S6, the composite material structure O after heat curing is sent out from the oven or autoclave apparatus together with the molding die 2 and the reinforcing bag 3. Then, the composite structure O after heat curing is taken out from the molding jig unit 1 including the reinforcing bag 3.

As a part of the removal operation of the composite material structure O, the reinforcing bladder 3 is detached from the composite material structure O after the heat curing. At this time, since the plate-like body 6 is not fitted into the side of the panel O1 of the cylindrical body 5 constituting the reinforced bag 3, the reinforced bag 3 can be easily deformed inward. Therefore, the reinforced bag 3 can be easily pulled out from the inside of the long structure O2 after heat curing. Further, the positioning member 9 for suppressing the flexure of the reinforced type bladder 3 can be extracted from the reinforced type bladder 3 after packaging or after heat curing.

The composite material molding method shown in fig. 6 is a method of producing a composite material structure O having a hollow structure by laminating a prepreg P1 for a panel O1 and a prepreg P2 for a long structure O2 and heating and curing the laminated prepregs, but a composite material structure O having a hollow structure can also be produced by a VaRTM method.

Fig. 7 is a flowchart showing a second example of a method of molding the composite structure O using the molding jig unit 1 shown in fig. 1.

First, in step S10, the sheet-like fibers F1 for the panel O1 are laminated on the forming die 2. On the other hand, in step S11, sheet-like fibers F2 for the long structure O2 as a reinforcing member of the panel O1 are laminated on the reinforced bag 3. The fiber F1 for the panel O1 and the fiber F2 for the long structure O2 can be stacked on the molding die 2 and the reinforcing bag 3, respectively, by an automatic stacking device. Alternatively, the worker may manually stack the fiber F1 for the panel O1 and the fiber F2 for the long structure O2. Further, since the adhesive force between the sheet-like fibers F2 is lost, the fibers can be bonded with an adhesive agent as needed.

Next, in step S12, the reinforcing bag 3 in which the sheet-like fibers F2 for the long structure O2 are laminated is placed on the sheet-like fibers F1 for the laminated panel O1.

Further, reinforcing bag 3 may be placed on sheet-like fiber F1 for panel O1, and then sheet-like fiber F2 for long structure O2 may be laminated on reinforcing bag 3. However, if the fibers F1 for the panel O1 and the fibers F2 for the long structure O2 are stacked and assembled, respectively, the working time is shortened.

Even when the composite material structure O is manufactured by the VaRTM method, it is preferable that the reinforcing type pockets 3 be placed on the sheet-like fibers in a state where the positioning members 9 for suppressing the rigid bodies of the reinforcing type pockets 3 are inserted into the reinforcing type pockets 3 from the viewpoint of placing the reinforcing type pockets 3 at more precise positions.

Next, packaging is performed in step S13. Specifically, the laminated sheet-like fibers F1 for the panel O1 and the sheet-like fibers F2 for the long structure O2 are covered with the packaging film 4. However, the laminate of the fibers F1 for the panel O1 and the laminate of the fibers F2 for the long structure O2 are covered with the packaging film 4 so that the interior of the reinforced bag 3 is not sealed and is open to the outside.

Then, the vacuum device 8 is driven, and air is discharged from the area covered by the packaging film 4. That is, the area covered with the packaging film 4 is depressurized by the vacuum apparatus 8. Thereby, a differential pressure between the atmospheric pressure applied from the outside of the packaging film 4 and the vacuum pressure in the region covered with the packaging film 4 is applied to the region covered with the packaging film 4.

Next, in step S14, uncured thermosetting resin is injected into the region covered with the packaging film 4. That is, the uncured thermosetting resin is supplied from the resin storage tank 10 into the region covered with the packaging film 4. This allows the fiber F1 for the panel O1 and the fiber F2 for the long structure O2 to be impregnated with uncured thermosetting resin.

The uncured thermosetting resin is not limited to be injected from the position where the fiber F1 for the panel O1 is laminated, and may be injected from the position where the sheet-like fiber F2 for the long structure O2 is laminated. Thus, the uncured resin can be quickly impregnated into the sheet-like fibers F2 for the long structure O2. As a result, the time required for impregnation of the resin can be shortened.

In the case of producing the composite structure O by the VaRTM method, when supplying the uncured resin from at least the position where the sheet-like fibers F2 for the long structure O2 are laminated, the resin supply port 4A is provided in the portion of the packaging film 4 covering the laminate of the fibers F2 for the long structure O2. Fig. 7 shows an example in which fibers are supplied from both the position of the fiber F1 for the laminated panel O1 and the position of the fiber F2 for the laminated elongated structure O2.

The inside of the reinforcing bag 3 is not sealed with the wrapping film 4 before and after the injection of the resin, and therefore, the inside is at atmospheric pressure. Therefore, the atmospheric pressure applied from the outside of reinforced bag 3 through laminate of packaging film 4 and fiber F2 impregnated with resin for long structure O2 is balanced with the atmospheric pressure applied to reinforced bag 3 from the inside of reinforced bag 3. The flat portions of the reinforced bag 3 bonded to the lid portion O3 and the web O4 of the uncured elongated structure O2 are reinforced by the first plate-like member 6A and the second plate-like member 6B, respectively.

As a result, the shape of the laminate of the fibers F2 impregnated with the resin for the long structure O2 can be shaped according to the shape of the long structure O2 after the resin is injected. Further, the reinforced bag 3 can hold the shaped shape of the laminate containing the fibers F2 impregnated with the resin for the long structure O2.

Next, in step S15, the laminate of the fibers F1 impregnated with the resin for the panel O1 and the laminate of the fibers F2 impregnated with the resin for the elongated structure O2 after packaging and resin injection, that is, the laminate is cured by heating with uncured thermosetting resin reinforced with sheet-like fibers.

Therefore, similarly to step S5 in fig. 6, the laminate of the fibers F1 impregnated with the resin for the panel O1 and the laminate of the fibers F2 impregnated with the resin for the elongated structure O2 are sent to an oven or an autoclave apparatus together with the molding die 2 and the reinforcing bag 3. Then, the composite structure O obtained by attaching the long structure O2 to the panel O1 was co-cured and molded by heating the laminate containing the fiber F1 impregnated with the resin for the panel O1 and the laminate containing the fiber F2 impregnated with the resin for the long structure O2 under pressure in an oven or an autoclave apparatus. As a result, the composite structure O in which the long structure O2 having a hat-shaped cross section is attached to the panel O1 can be produced with good quality.

Next, in step S16, the composite material structure O after heat curing is sent out from the oven or autoclave apparatus together with the molding die 2 and the reinforcing bag 3. Then, the composite structure O after heat curing is taken out from the molding jig unit 1 including the reinforcing bag 3. At this time, as in step S6 of fig. 6, the reinforcing bag 3 can be easily pulled out from the inside of the long structure O2 by deforming the panel O1 side of the reinforcing bag 3 which is not reinforced by the plate-like body 6 inward.

In addition to the composite material molding method shown in fig. 6 and 7, as described above, a composite material structure O in which a long structure O2 having a hat-shaped cross section is attached to a panel O1 can be produced by a hybrid molding method combining prepreg lamination and VaRTM. Specifically, for the panel O1, a laminate of resin-impregnated fibers F1 was produced by laminating prepregs P1, while for the long structure O2, a laminate of resin-impregnated fibers F2 was produced by the VaRTM method. Of course, the composite structure having a desired hollow structure can be produced by the above-described composite molding method without being limited to the composite structure O in which the long structure O2 having a hat-shaped cross section is attached to the panel O1.

(Effect)

In the composite material molding method as described above, a composite material structure having a hollow structure is molded using the reinforced type bladder 3 partially reinforced by the rigid plate-like body 6 as a core jig. That is, the reinforced bladder 3 provides the bladder with a shape-retaining function and retains stretchability necessary for molding.

Therefore, according to the composite material molding method using the reinforced bladder 3, when a composite material structure having a hollow structure is molded, the structure of the jig can be simplified as compared with the conventional one while ensuring the degree of freedom in design.

Fig. 8 is a diagram showing a composite material molding method of a conventional OML jig method in which a composite material structure having a hat-shaped cross section is molded using a mandrel as a core jig.

As one of conventional composite material molding methods for producing a composite material structure O in which a long structure O2 having a hat-shaped cross section is attached to a panel O1, there is a method in which, as shown in fig. 8, the OML side of a panel O1 is set to be downward, a composite material structure O before curing is placed on an OML molding die 20, and a solid mandrel 21 is placed on the inside of a long structure O2 before curing. However, in the case of using the solid mandrel 21, the shape of the composite material structure O is defined as a shape that can be extracted into the mandrel 21. Moreover, the process involving the conveyance of the mandrel 21 requires labor.

In contrast, the reinforcing bag 3 can be deformed, and therefore can be easily pulled out from the inside of the long structure O2 after heat curing. Therefore, it is possible to secure a degree of freedom in designing a composite structure having another hollow structure, not only the composite structure O in which the long structure O2 having a hat-shaped cross section is attached to the panel O1. Further, the reinforced bladder 3 is hollow, so that it is light in weight and easy to handle including transportation.

Fig. 9 is a diagram showing a composite material molding method by a conventional IML jig method in which a composite material structure having a hat-shaped cross section is molded using upper and lower molding dies and a general bag.

As another conventional composite material molding method for producing a composite material structure O in which an elongated structure O2 having a hat-shaped cross section is attached to a panel O1, there is a method in which, as shown in fig. 9, the IML side of a panel O1 is set to the lower side, an unreinforced bag 30 is inserted into the inner side of the elongated structure O2 before curing, and the entire composite material structure O before curing is supported from both directions by an IML-side molding die 31 and an OML-side molding die 32. However, in the case of the IML jig method, the structure of the IML-side forming mold 31 becomes complicated. Further, since the panel O1 before and after curing is supported by the unreinforced bladder 30, there is a disadvantage that the support of the panel O1 is unstable.

On the other hand, if the composite material structure O is manufactured by the OML jig method using the reinforcing bladder 3, a forming mold having a complicated structure is not necessary. Further, the panel O1 can be stably supported by the rigid forming die 2.

Fig. 10 is a diagram showing a composite material molding method of a conventional OML jig method in which a composite material structure having a hat-shaped cross section is molded using upper and lower molding dies and a general bag.

As another conventional composite material molding method for producing a composite material structure O in which a long structure O2 having a hat-shaped cross section is attached to a panel O1, there is a method in which, as shown in fig. 10, the OML side of a panel O1 is set to be downward, an unreinforced bag 40 is inserted into the long structure O2 before curing, and the composite material structure O before curing is supported in its entirety from both directions by an IML side molding die 41 and an OML side molding die 42 called cover plates.

On the other hand, if the composite material structure O is manufactured by the OML jig method using the reinforcing type bladder 3, it is possible to eliminate the need for a cover plate of the IML side forming mold 41. That is, the reinforcing bladder 3 is not formed into a cylindrical shape during the heat curing of the composite material structure O without using a cover sheet, and the lid portion O3 or the web O4 can be prevented from being dented or distorted due to the influence of gravity.

Further, if the reinforced bladder 3 is used, the clamp which is currently placed on the atmosphere side can be omitted. Therefore, the labor and time required for placing, removing, cleaning, and the like of the jig can be reduced. In addition, the weight of the composite material structure O including the jig can be reduced. Therefore, not only the transportation becomes easy, but also the volume of the heating target can be reduced. As a result, the time and energy required for heat curing of the composite material structure O can be reduced.

In the composite material molding method using the reinforced type bladder 3, unlike the conventional composite material molding method in which uncured resin is sandwiched between upper and lower rigid body molding dies, no rigid body molding die is provided on the atmosphere side. Therefore, the composite material structure O can be uniformly applied with a pressure corresponding to the atmospheric pressure during the heat curing. As a result, the composite structure O can be produced with good quality.

Further, since no rigid molding die is provided on the atmosphere side, when the composite material structure O is manufactured by the VaRTM method, the resin injection position can be provided on the long structure O2 side. This can shorten the time required for impregnating the fibers with the resin, which is a problem in the VaRTM process. Further, a Resin Distribution medium (Resin Distribution Media) made of a mesh of plastic or the like may be disposed to efficiently impregnate the outer side of the long structure O2 with Resin.

(second embodiment)

Fig. 11 is a cross-sectional view showing the structure of a reinforced type bladder as a composite material molding jig according to a second embodiment of the present invention.

The molding jig unit 1A of the second embodiment shown in fig. 11 differs from the molding jig unit 1 of the first embodiment in that the third plate-like body 6C is fitted into the cylindrical body 5 of the reinforced bag 3A on the side of the panel O1. Since other configurations and functions of the forming jig unit 1A of the second embodiment are not substantially different from those of the forming jig unit 1 of the first embodiment, the same or corresponding configurations are denoted by the same reference numerals and description thereof is omitted.

As shown in fig. 11, the tubular body 5 constituting the reinforced bag 3A can be fitted with the first plate-like body 6A on the lid portion O3 side of the long structure O2 having a hat-shaped cross section and the two second plate-like bodies 6B on the web portion O4 side of the long structure O2, and can be fitted with the third plate-like body 6C on the panel O1 side. Accordingly, even on the side of panel O1, reinforced bag 3A can be reinforced by third sheet-like body 6C.

When the third plate-like body 6C is fitted into the cylindrical body 5 on the side of the panel O1, the plate-like body is preferably divided into a plurality of plate members. That is, the plurality of third platelike bodies 6C are preferably arranged on the side of the panel O1 of the cylindrical body 5 so as not to overlap with each other. In the example shown in fig. 11, the two third tabular bodies 6C are fitted into the tubular body 5 on the side of the panel O1 with a gap.

When reinforced type bag 3A is reinforced by third plate 6C divided in this manner, reinforced type bag 3A on the side of panel O1 can be partially reinforced by third plate 6C, and reinforced type bag 3A can be easily folded on the side of panel O1. Therefore, the reinforced bag 3A can be easily extracted from the composite material structure O after the heat curing.

This is not limited to the composite structure O having a structure in which the long structure O2 having a hat-shaped cross section is attached to the panel O1, but may be the same in the case of manufacturing a composite structure having another hollow structure. That is, if the cylindrical body 5 is reinforced in the same direction by the plurality of plate-like bodies 6 arranged in parallel with the thickness direction facing the same direction, the strength of the reinforced bladder 3A is locally reinforced, and the reinforced bladder 3A is bent, whereby the reinforced bladder can be easily extracted from the composite material structure having a hollow structure.

(third embodiment)

Fig. 12 is a cross section showing the structure of a reinforced type bladder as a composite material molding jig according to a third embodiment of the present invention.

A forming jig unit 1B according to a third embodiment shown in fig. 12 is different from the forming jig unit 1 according to the first embodiment in that a part of a plate-like body 6 is fitted into a cylindrical body 5 constituting a reinforced type bladder 3B. Since other configurations and functions of the forming jig unit 1B of the third embodiment are not substantially different from those of the forming jig unit 1 of the first embodiment, only the reinforcing pockets 3B are illustrated, and the same configurations and corresponding configurations are denoted by the same reference numerals and are not described.

As shown in fig. 12, the reinforced bladder 3B can be configured by fitting only a part of the plate-like body 6 into the cylindrical body 5 without fitting the entire plate-like body 6 into the cylindrical body 5. Thus, the plate-like body 6 can be replaced as necessary. Therefore, for example, in the case where the plate-like body 6 is deformed or in the case where the plate-like body 6 having different strength is used, the plate-like body 6 can be easily replaced. Of course, in the second embodiment, instead of fitting the entire plate-like body 6 into the cylindrical body 5, only a part of the plate-like body 6 may be fitted into the cylindrical body 5.

(fourth embodiment)

Fig. 13 is a cross section showing the structure of a reinforced type bladder as a composite material molding jig according to a fourth embodiment of the present invention.

A forming jig unit 1C according to a fourth embodiment shown in fig. 13 is different from the forming jig unit 1 according to the first embodiment in that a plate-like body 6 is attached to an inner surface of a cylindrical body 5 constituting a reinforced type pocket 3C. Since other configurations and functions of the forming jig unit 1C of the fourth embodiment are not substantially different from those of the forming jig unit 1 of the first embodiment, only the reinforcing pockets 3C are illustrated, and the same or corresponding configurations are denoted by the same reference numerals and are not described.

As shown in fig. 13, reinforcing bladder 3C may be configured by attaching one surface of plate-like body 6 to the inner surface of cylindrical body 5 with an adhesive, without fitting plate-like body 6 into cylindrical body 5. Thus, not only the plate-like body 6 can be replaced as needed, but also the reinforcing bag 3C can be produced by attaching the plate-like body 6 to an existing bag. Therefore, as in the third embodiment, for example, in the case where the plate-like body 6 is deformed or the plate-like body 6 having different strength is used, the plate-like body 6 can be easily replaced or attached. Of course, in the second embodiment, instead of fitting the plate-like body 6 into the cylindrical body 5, one surface of the plate-like body 6 may be attached to the inner surface of the cylindrical body 5.

(other embodiments)

While the specific embodiments have been described above, the embodiments described above are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein can be implemented in a variety of other ways. Various omissions, substitutions, and changes in the form of the methods and apparatus described herein may be made without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover the scope and spirit of the invention, and include such various aspects and modifications.