JP2002011813A - Sandwich structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sandwich structure which can be easily processed. SOLUTION: As the sandwich structure 80 has such a sandwich structure that has a closed-cell foamed plastic material 85 and a honeycomb core 81 as core materials 86 and is pinched by face plates 83 and 84 consisting of a composite material in which an inorganic fiber with an affinity with water is used as a reinforcing fiber, water does not penetrate inside. In this sandwich structure, the foamed plastic material 85 is used as the core material in the part where plate pressure is largely changed and the honeycomb core 81 is used as the core material in the part where the plate pressure is mildly changed. It is possible thereby to facilitate the processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sandwich structure used for structures such as aircraft, railway vehicles, automobiles, and ships.

[0002]

2. Description of the Related Art Conventionally, lightweight metal reinforcing plate structures such as aluminum alloys have been used as structures for aircrafts and the like. In recent years, however, composite reinforcing plate structures and honeycomb cores have been used as core materials. A sandwich structure whose surface is covered with a composite face plate has been used.

[0003]

In the case of a sandwich structure having a large change in plate thickness, it is necessary to machine the honeycomb core, but machining the honeycomb core is a laborious operation.

[0004] It is an object of the present invention to provide a sandwich structure in which core material can be easily processed.

[0005]

According to the present invention, there is provided a composite material in which a closed-cell foamed plastic material and a honeycomb core are used as a core material, and both surfaces of the core material are made of inorganic fibers having no affinity for water as reinforcing fibers. A sandwich structure covered with a face plate made of a material, wherein a foamed plastic material is used as a core material in a portion where the thickness changes greatly, and a honeycomb core is used as a core material in a portion where the thickness changes gradually. Structure.

According to the present invention, since a foamed plastic material which can be easily processed and can be smoothly processed even in a portion having a large thickness change is used, processing of the core material is easy and lamination of the composite material face plate is easy. Can be realized.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment on which the present invention is based.
2 is an exploded perspective view showing the sandwich structure 50 of FIG. The sandwich structure 50 is used, for example, as an outer skin of an aircraft. The core 51 is made of a closed-cell foamed plastic material, and both surfaces of the core are made of a fiber-reinforced composite material.
2 and 53. The foamed plastic material is, for example, polymethacrylimide (PMI) or polyvinyl chloride (PVC), which is a closed-cell foamed plastic material. The face plates 52 and 53 are made of a fiber reinforced composite material using inorganic fibers having no affinity for water, for example, carbon fibers as reinforced fibers. It is configured by lamination.

When the core members 51 of the sandwich structure 50 are joined to each other, a film-like adhesive 54 that does not foam at the joining portion, for example, Cytec FM300K (trade name) is used. The face plates 52 and 53 and the core material 51 are formed of a film-like adhesive 55 containing no carrier, for example, Cy.
TEC FM300U (trade name). By bonding with a film-like adhesive containing no carrier, no gap is formed between the face plates 52 and 53 and the core material 51, so that water can be prevented from entering. In addition, the core material 51 and the face plates 52, 53 are not bonded by using a film-like adhesive, but the face plates 52, 5 which are a composite material.
The third resin may be used. That is, the prepregs to become the face plates 52 and 53 are directly attached to both surfaces of the core material 51, and the prepreg is cured by heating under pressure, and the face plates 52 and 53 and the core material 51 are bonded.

Further, since the core 51 is made of a closed-cell foamed plastic material, water is prevented from penetrating into the core. In addition, since the adhesive between the core materials uses a film-like adhesive 54 that does not foam, the face plates 52 and 53 are damaged,
Even if water invades, it is possible to prevent the water that has entered along the joint surface of the core material 51 from spreading into the sandwich structure 50.

FIG. 2 is a sectional view showing a sandwich structure 80 according to an embodiment of the present invention. In the present embodiment, the core material 86 is composed of the honeycomb core 81 and the foamed plastic material 85. The foamed plastic material 85 is used for the portion of the sandwich structure 80 where the thickness change is large, and the portion where the thickness change is gentle is the honeycomb. The core 81 is used. The material and the like are the same as those of the above-described sandwich structure.

In the case of a sandwich structure having a large change in plate thickness, it is necessary to machine the honeycomb core. However, since machining of the honeycomb core is a time-consuming operation, in the present embodiment, where the change in the plate thickness is large, By using the foamed plastic material 85 that is easy to machine and using the honeycomb core 81 in the portion where the thickness changes gradually, the processing of the core material 86 becomes easy. The face plates 83 and 84 are made of prepreg and are formed by being laminated on a core material 86. The bonding between the face plates 83 and 84 and the core material 86 uses a film-like adhesive 87 that does not include a carrier. Also, face plates 83, 8
As the reinforcing fiber of No. 4, an inorganic fiber having no affinity for water is used as described above.

Next, a method of repairing the sandwich structure will be described. FIG. 3 is a cutaway perspective view of the damaged sandwich structure 1. The sandwich structure 1 is a composite material having a sandwich structure in which both surfaces of a plate-like core material 4 having a thickness of 12.7 mm are covered with face plates 2 and 3. The core 4 is made of a closed-cell foamed plastic material.
Is a fiber-reinforced composite material using inorganic fibers having no affinity for water as reinforcing fibers. The sandwich structure 1 of the present embodiment includes:
For example, it is used as an outer plate of a passenger transport aircraft such as an aircraft and a high-speed rail vehicle.

Note that the face plate 2 of the sandwich structure 1 is on the outer surface side, and the face plate 3 is on the inner surface side. The outer face plate 2
A fiber-reinforced composite material formed by laminating eight prepregs in which a resin is impregnated in a cloth material made of reinforcing fibers,
The inner face plate 3 is thinner than the face plate 2 and is a fiber reinforced composite material in which four prepregs are laminated.

In FIG. 3, reference numeral 5 is a damaged portion,
In order to repair the damaged portion 5, the face plate 2 in the area including the damaged portion 5 is first cut out. For this purpose, a hole saw 11 shown in FIG. 4 is used. The hole saw 11 has a cylindrical shape, and has a sawtooth 12 formed at the distal end thereof over the entire outer circumference. The saw 12 can be hollowed out by rotating at high speed around an axis. Therefore, by using the hole saw 11 having a diameter larger than the damaged portion 5, the face plate 2 in the region including the damaged portion can be hollowed out. By digging out the damaged portion in a circular shape in this way, the concentration of stress can be suppressed low. In the present embodiment, the diameter of the hole saw 11 is, for example, 50 mm. As shown in FIG. 4, together with the face plate 2, a core material 4 below the face plate 2 is provided.
Are also cut out in a circle. Thus, a circular opening 10 is formed in the face plate 2.

Next, the lower part of the opening 10 of the face plate 2 and the opening 10
The core material 4 at the periphery is removed. Since the core material 4 is a foamed resin as described above and the face plates 2 and 3 are a fiber-reinforced composite material, only the core material 4 can be efficiently removed by using a blast shot.

FIG. 5 is a perspective view showing a core material removing operation.
FIG. 6 is a sectional view at that time. As blast material,
For example, walnut powder, alumina, cone, or the like is used. By injecting such a blast material from the blast injection nozzle 15 toward the core material 4, only the core material 4 can be scraped.

As shown in FIG. 6, the core material 4 attached to the back side of the face plate 2 is removed by using a blast injection nozzle 15 whose tip end is bent by 180 ° as shown in FIG.
0 to easily insert the blast nozzle 15
Can be removed.

After the core 4 has been removed, the support plate 16 is mounted. FIG. 7 is a plan view showing a state where the support plate 16 is mounted, and FIG. 8 is a cross-sectional view thereof. As shown in FIG. 7, the support plate 16 can be extended in a radial or petal shape, and is made of a titanium alloy. The support plate 16 has a central circular support portion 17 and a plurality of rectangular, and a plurality of, in this embodiment, eight support pieces 1 radiating radially outward from the support portion 17.
8 and is formed by cutting from one titanium alloy plate. The central circular support portion 17 has a smaller diameter than the opening 10. The entire size of the support plate 16 including the support pieces 18 is formed sufficiently larger than the opening 10.

The support plate 16 is inserted from the opening 10, and each support piece 18 is attached to the back of the face plate 2 around the opening 10 by the rivet 2.
Linked by 5. When the support plate 16 is inserted from the opening 10, each support piece 18 is inserted into the opening 10 with the support piece 18 being curved inward, and the support piece 18 is spread within the opening 10.
Next, a through hole 24 for inserting the rivet 25 is formed by drilling from the face plate 2 to the support piece 18.
The through holes 24 may be separately formed in the support plate 16 and the face plate 2 in advance.

Next, each support piece 18 of the support plate 16 and the face plate 2 are fixed by rivets 25. FIG. 9 shows rivets 25
FIG. 4 is a cross-sectional view illustrating a method of tightening. The rivet 25 is a blind rivet that can be swaged from one side, and the head 26 has a dish shape and is smooth without protruding above the outer surface of the face plate 2.

The rivet 25 has a hollow shaft portion 27, and a drawing bar 28 is inserted into the shaft portion 27. Shaft 2
A sleeve 30 is attached to the tip of the extraction rod 28 projecting from
Is inserted, and the distal end of the extraction rod 28 is connected to the solid core bolt 31 at the distal end of the sleeve 30. Also,
A coiled washer 32 is provided at the base end of the sleeve 30, and the tip of the shaft 27 is tapered.

The rivet 25 is inserted into the through hole 24 from the front side of the face plate 2 as shown in FIG. Next, when the pull-out rod 28 is pulled out with a tool, the coiled washer 32 is guided by the tapered portion at the tip of the shaft portion 27 to be unwound and expanded as shown in FIG. Further pull rod 2
When 8 is pulled out, the coiled washer 32 contacts the back surface of the support plate 16 and is completely swaged. Finally, the drawing bar 28 is cut, and the rivet caulking operation is completed. In this way, the eight support pieces 18 of the support plate 16 are connected to the face plate 2 by the rivets 25, respectively.

Next, the opening 10 is closed with a cover plate 40. The cover plate 40 is made of a fiber-reinforced composite material having the same thickness as the face plate 2, and is formed to have the same size as the opening 10. Therefore,
Using the hole saw 11 used to form the opening 10, a fiber-reinforced composite material having the same thickness as the face plate 2 is cut out in a circular shape.

Using the cover plate 40, the opening 10 is closed as shown in FIG. As shown in FIG. 7, the support plate 16 has a central circular support portion 17 exposed at the center of the opening 10 and a peripheral support piece 18 provided on the support plate 2.
, The cover plate 40 is arranged on the central support portion 17. Next, insertion holes for inserting the rivets 25 are formed by drilling the cover plate 40 from the cover plate 40 to the support plate 16 at eight positions, for example, corresponding to the support pieces 18. And, as before, blind rivet 2
5, the support plate 26 and the cover plate 40 are connected. Since the cover plate 40 has the same thickness as the face plate 2, the support plate 16
The surface of the face plate 2 becomes smooth by fixing it on the upper side.

After joining the cover plate 40 with the rivets 25, two through holes 41 and 42 are formed on the cover plate 40, and a filler 43 is injected from one of the through holes 41. Filler 43
Is a liquid foamed resin containing fine bubbles, and is injected from the through hole 41 by an injection gun. Filled filler 43
Is filled with a recess formed by removing the core material 4, and FIG.
When completely filled as shown in FIG.
Come out of two. This makes it possible to confirm that the filling has been completed. After injecting the filler, the filler 43 is completely cured by being left for a predetermined time. The filling material 43
Cures at room temperature.

In this manner, the sandwich structure 1 can be easily repaired using rivets without using any special device. Further, the support plate 16 is made of a titanium alloy, and the titanium alloy and the fiber reinforced composite material of the face plates 2 and 3 have a thermal expansion coefficient closer to that of an aluminum alloy or the like. Therefore, even if they are joined with the rivets 25, it is possible to prevent the occurrence of excessive thermal stress during use.

In the present embodiment, the radial support plate 16 is used as the support plate 16, but the present invention is not limited to this. For example, a plurality of support plates are connected to the back side of the periphery of the opening 10 by rivets, and the support plate is supported. The plate may be partially exposed to the opening 10, the cover plate 40 may be placed on the exposed support plate, and the cover plate and the support plate may be joined by rivets.

Although the present embodiment has been described on the assumption that the repair is performed only from the damaged front side, if the repair work can be performed from the back side of the outer plate, the outer plate is penetrated by the hole saw 11, that is, the inner surface is repaired. An opening is formed through the face plate 3. As a result, the work can be performed not only from the front side but also from the back side, so that the work of removing the core material 4 can be easily performed. Further, since the back side is not noticeable and does not need to be smoothed, a cover plate larger than the opening may be directly connected to the face plate 3 by rivets without using a support plate.

FIG. 12 is a sectional view showing a method of repairing the sandwich structure 1 according to still another embodiment of the present invention. In addition,
In the configurations corresponding to FIGS. 3 to 11 described above, the same reference numerals are given, and the description is omitted.

The repair method of the present embodiment is a repair method in a case where repair can be performed from the face plate 3 inside the sandwich structure 1. The inner face plate 3 and the core 4 corresponding to the back side of the damaged portion 5 are removed in the same manner as described above by spraying the hole saw 11 and the blast material. Next, the upper support plate 45 is brought into contact with the back side of the face plate 2 so as to cover the damaged portion 5 on the back side of the face plate 2 on the outer surface side, and is joined with the rivets 25. The upper support plate 45 is made of a titanium alloy or a fiber-reinforced composite material similar to the face plate 2. Next, the core removing portion is filled with the filler 43, and then the opening of the inner face plate 3 opened by the hole saw 11 is
6 and is connected to the face plate 3 by rivets 25. By repairing in this manner, it is possible to repair without forming an opening in the outer surface side plate 2.

In the repair method of the present embodiment, the sandwich structure is made of only the foamed plastic material as the core material. However, the present invention is not limited to such a form. As shown in FIG. 2, the honeycomb core and the foamed plastic material are used as the core material. The repair method of the present invention can also be applied to the case of a sandwich structure. Further, for the sandwich structure, a film-like adhesive as described in FIGS. 1 and 2 may be used.

[0032]

According to the present invention, processing of the core material is facilitated by using a foamed plastic material for a portion where the thickness change is large and using a honeycomb core for a portion where the thickness change is gentle. be able to.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a sandwich structure 50. FIG.

FIG. 2 is a sectional view showing a sandwich structure 80 according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a damaged sandwich structure 1;

FIG. 4 is a perspective view showing a method for hollowing out a damaged portion.

FIG. 5 is a perspective view showing a method of removing a core material 4;

FIG. 6 is a sectional view of the sandwich structure 1 showing a method of removing the core material 4;

FIG. 7 is a plan view of the sandwich structure 1 showing a state where the support plate 16 is attached.

FIG. 8 is a sectional view of the sandwich structure 1 showing a state where the support plate 16 is attached.

FIG. 9 is a cross-sectional view showing a method of caulking the rivet 25.

FIG. 10 is a perspective view of the sandwich structure 1 showing a state where the cover plate 40 is attached.

FIG. 11 is a cross-sectional view showing the sandwich structure 1 in a state where the filler 43 is injected.

FIG. 12 is a sectional view showing another embodiment of the method for repairing a sandwich structure of the present invention.

[Explanation of symbols]

 1, 50, 80 Sandwich structure 2, 3, 52, 53, 83, 84 Face plate 4, 51, 86 Core material 5 Damaged portion 10 Opening 11 Hole saw 12 Saw tooth 16 Support plate 25 Rivets 40 Cover plate 43 Filler 45 Upper support plate 46 Lower support plate 54, 55, 87 Film-like adhesive 85 Foamed plastic material 81 Honeycomb core

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AA01B AA01C AD11 AK01A AK15 AK49 AK53 BA03 BA06 BA10B BA10C BA42A CB00 DC01A DG01B DG12 DH02B DH02C DJ02A GB31 JB06B JB06C JL01

Claims (1)

[Claims] 1. A sandwich structure in which a closed-cell foam plastic material and a honeycomb core are used as a core, and both surfaces of the core are covered with a face plate of a composite material using inorganic fibers having no affinity for water as reinforcing fibers. A sandwich structure characterized by using a foamed plastic material as the core material for parts with large thickness changes, and using a honeycomb core as core material for parts with gentle plate thickness changes.