JPH02162032A - Honeycomb sandwich construction and its manufacture - Google Patents

Abstract

PURPOSE:To connect a skin to a honeycomb core firmly, while the adhesive in prepreg flows out, whereby a fillet is formed at the crossing where the skin and honeycomb are stuck to each other by a method in which fiber reinforced plastic prepregs arranged on both surfaces of the honeycomb core are set in a vacuum bag, and the pressure applied to the vacuum bag in heating is held in a specified value. CONSTITUTION:The prepregs 1, 2 of glass fiber reinforced plastic arranged on both surfaces of a honeycomb core 3, are placed on a jig 5, and are covered with a vacuum bag 4. The pressure inside of the vacuum bag 4 is reduced to at least 23 is Hg. The prepregs 1, 2 on the jig 5, the honeycomb core 3 and the vacuum bag 4 are introduced into a furnace 6, and while the pressure in the furnace is kept at 20-35 PSIG, they are heated, thereby curing the prepregs 1, 2. Then a fillet 7 is formed at the crossing where the skin adheres to the honeycomb core, and while both members are mutually connected firmly, the rigidity of the skin 1a, 2a is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a honeycomb sandwich structure with improved soundproofing performance that can be applied to lining materials for aircraft, etc., and a method for manufacturing the same.

[Conventional technology]

In manufacturing conventional honeycomb sandwich structures,
As shown in FIG. 6(G), a honeycomb core 03 is placed between the upper and lower fiber-reinforced plastic prepregs 01 and 02, placed on a jig 05, and further placed between the prepregs 01 and 02 in a vacuum bag 04. and covers the honeycomb core 03, and the inside of the vacuum bag 04 is maintained at a minimum of 23 inHg.
After reducing the pressure to a certain level, the furnace was heated to 0.
260±1 for 90 to 180 minutes under atmospheric pressure.
The honeycomb sandwich structure 4 was manufactured by curing the prepreg 01.02 by heating at a temperature of about 0.0 or below.

[Problem to be solved by the invention]

In the conventional honeycomb sandwich structure described above, the prepreg hardens to form upper and lower skins, and the honeycomb core exists between them. However, the skin and honeycomb core are simply separated as the prepreg hardens. The skin and honeycomb core are only bonded at their joint surfaces, and the adhesion between the skin and the honeycomb core is weak, and therefore the rigidity of the skin is low. Therefore, when the sound waves reach one of the skins, the skin moves away from the honeycomb core and performs a bending movement as shown by the dotted line in Figure 5@), thereby compressing the air within the honeycomb sandwich structure as a whole. There is no expansion, so the structure has a double skin structure, but the skin on one side of the structure and the air inside the structure do not substantially contribute to soundproofing, and the soundproofing effect is comparable to that of a single layer structure. It merely served a function.

Therefore, in order to improve the soundproofing performance, it was necessary to increase the weight tt of the honeycomb sandwich structure itself.

The present invention seeks to overcome the above-mentioned drawbacks of conventional honeycomb sandwich structures.

[Means to solve the problem]

(1) The honeycomb sandwich structure of the present invention includes a honeycomb core, a skin adhered to both surfaces of the honeycomb core, and a fillet formed at an intersection where the honeycomb core and the skin adhere.

(2) The present invention also relates to a method for manufacturing the above-mentioned honeycomb structure, in which a honeycomb core with fiber reinforced plastic (hereinafter referred to as FRP) prepreg arranged on both sides is placed in a vacuum bag. In a method for manufacturing a honeycomb sandwich structure in which the inside of a nuclear vacuum bag is heated while maintaining a reduced pressure state, the pressure applied to the vacuum bag during the heating was maintained at 20 to 35 PSIG.

[Effect]

According to the manufacturing method (2) above according to the present invention, a vacuum bag kept in a reduced pressure state [one-sided FRP prepreg is pressure-welded to a honeycomb core in order to heat it by applying a pressure of 20 to 35 PSIG. As the prepreg is heated and cured, the adhesive inside the prepreg flows out and a fillet is formed at the intersection of the honeycomb core and the skin formed by the curing of the prepreg, and the two are firmly bonded. be done.

Further, a honeycomb structure having the configuration of the present invention described in (1) above is manufactured.

In the present invention (1) above, a fillet is formed at the intersection where the skin and the honeycomb core are bonded, and the skin and the nicum core are bonded together through the fillet in addition to the adhesion between the skin and the nicomb core. To be joined, the two are strengthened and joined together.

Therefore, when a sound wave reaches one of the skins, and the skin and the honeycomb core are firmly connected to each other, the skin has high rigidity, and the skin moves as a rigid body to compress the air within the same structure. This results in sound absorption.

In this way, the structure of the present invention (1) has soundproofing properties due to the double structure of the skin, and the soundproofing performance is significantly improved compared to the conventional honeycomb sandwich structure.

(9) In the manufacturing method of the present invention described in (2) above.

If the pressing force of the vacuum bag is less than 20 PSIG, the fillet will not be formed and the honeycomb structure will not have the soundproofing performance of a double structure, whereas if the pressing force exceeds 35 PSIG,
The honeycomb bites into the prepreg, causing unevenness on the surface and making the product unusable. Therefore, in the manufacturing method of the present invention, the pressure applied to the vacuum bag was selected to be in the range of 20 to 35 PSIG.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

In the present invention, as in the conventional method shown in FIG.
Glass fiber reinforced plastic (
Prepregs 1 and 2 made of material (hereinafter referred to as GFRP) were placed on a jig 5 and covered with a vacuum bag 4, and the pressure inside the vacuum panda 4 was reduced to a minimum of about 23 inHg. This jig 5
Upper prepregs 1 and 2, honeycomb core 3 and true nitrogen bag/
'4 into the furnace 6, and set the furnace pressure to 20-35 PSIG.
In the same furnace, the temperature in the furnace was increased to 260±1 for 90 to 180 minutes.
07 and heated to harden the prepregs 1 and 2.

The honeycomb sandwich structure obtained in this way has skins 1a and 2a made of hardened prepreg 1°2, and 1m of the same skin, as shown in FIG.

The honeycomb core 3f is bonded to the honeycomb core 2a, and a fillet 7 is formed at the intersection where the skin 1 and the honeycomb core are bonded. The honeycomb core 3 is bonded to the honeycomb core 3 so that the two are strengthened and joined together, and the rigidity of the skins 1a and 2a is improved.

The honeycomb sandwich structure τ according to this example is GF
The skins 1a and 2a made of RP are strongly connected to the honeycomb core 31C as described above and have high rigidity, so that when the sound wave reaches one of the skins 1a and 2a, as shown in
As shown by the dotted line in (g), the skin moves as a rigid body (piston movement), which compresses the air inside the honeycomb sandwich structure. Therefore, sound is converted into thermal energy, sound absorption is performed, and the single structure fully exhibits the characteristics of a double structure.

This results in effective soundproofing.

*Related to the present invention? Experimental examples relating to a machine cam sand inch structure and a manufacturing method thereof will be described below.

The GFRP prepreg and honeycomb core used in the experiment are as shown in Table 1, where A1 is the inboard prepreg,
A2 is the honeycomb core, and Ya3 is the outer prepreg.

Margin table below: 1 Place this on a jig, cover it with an empty PC bag, create a vacuum inside the vacuum bag, and heat it at the pressure, heating temperature, and heating time shown in Figure 3 to remove both epidermis. A honeycomb sandwich structure was obtained in which fillets were formed at adhesive intersections of honeycomb cores.

When we compared the soundproofing performance of this structure and a conventional honeycomb sandwich structure, we obtained the results shown in Figure 4.
The structure of the present invention has a frequency of 7d at 1000Hz (IKHz) or higher.
It was found that the performance was markedly excellent, at grade B.

〔Effect of the invention〕

The present invention can have the following effects.

(1) By forming a double-layered honeycomb sandwich structure in which both skins and a honeycomb core are firmly bonded, soundproofing performance can be significantly improved.

(2) The above-mentioned soundproofing performance can be improved without increasing weight and space.

(3) The above-mentioned honeycomb sandwich structure with excellent soundproofing performance can be manufactured through a simple process.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the honeycomb sandwich structure according to the present invention, FIG. 2 is an explanatory diagram of an embodiment of the manufacturing method of the present invention, and FIG. 3 is an explanatory diagram of an example of the pressurizing pressure of an experimental example of the present invention. , a graph showing the heating temperature and heating time, FIG. 4 is a graph showing the sound insulation performance of the honeycomb sandwich structure according to the above experimental example and the conventional honeycomb sandwich structure, FIG. 5 (4),
B) is an explanatory diagram showing the vibration states of a honeycomb sandwich structure according to an embodiment of the present invention and a conventional honeycomb sandwich structure due to sound waves, respectively. FIG. 6(F) is an explanatory view showing a conventional method for manufacturing a honeycomb sandwich structure. 1.2...C, F RP material prepreg, la, 2a
... skin, 3 ... honeycomb core, 4 ... vacuum bag, 5 ... jig, 6 ... furnace, 7 ... fillet. Agent: Patent attorney Akira Sakama and 2 others 81 Figure 83

Claims (2)

[Claims] (1) A honeycomb sandwich structure comprising a honeycomb core, a skin adhered to both surfaces of the honeycomb core, and a fillet formed at an intersection where the honeycomb core and the skin adhere. (2) In a method for manufacturing a honeycomb sandwich structure material, in which a honeycomb core with prepregs of fiber-reinforced plastic material arranged on both sides is placed in a vacuum bag and heated while maintaining the inside of the vacuum bag in a reduced pressure state, during the heating. A method for manufacturing a honeycomb sandwich structure, characterized in that the pressure applied to the vacuum bag is maintained at 20 to 35 PSIG.