JP2002321238A - Method for manufacturing perforated sheet for sound absorbing panel of airplane engine nacelle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a perforated sheet for the sound absorbing panel of an airplane engine nacelle having accurate perforations adjusted in shape by facilitating the application of a prepreg perforated surface sheet perforated at the time of production of a perforated sheet to a curved surface mold and the shaping thereof by the mold and preventing the perforations of the prepreg perforated surface sheet from being closed by a resin in a prepreg at the time of curing under heating and pressure. SOLUTION: In the method for manufacturing the perforated sheet for the sound absorbing panel of the airplane engine nacelle, a predetermined number of prepreg surface sheets, each of which is prepared by impregnating a reinforcing fiber fabric with a resin hard to flow, are laminated and a large number of perforations are bored in the laminated prepreg surface sheet by punching and, next, the formed laminated prepreg surface sheet is applied to the curved surface mold to be shaped. This shaped prepreg perforated surface sheet is covered with a release film high in elongation and further covered with a back film to be attached to the peripheral edge of the curved surface mold through a seal material. Subsequently, the interior of the back film is evacuated to allow the release film and the back film to comform to the inner surfaces of a large number of perforations of the laminated prepreg perforated surface sheet and, thereafter, the laminated prepreg perforated surface sheet is introduced into an autoclave along with the curved surface mold to be cured under heating and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a perforated plate for an aircraft engine nacelle sound absorbing panel.

[0002]

2. Description of the Related Art In order to prevent noise generated by an engine, an aircraft uses a honeycomb sandwich structure having a sound absorbing performance called a sound absorbing panel in a portion called an engine nacelle which covers the engine. As the face plate of this honeycomb sandwich structure, a perforated plate having a large number of holes is used, and this perforated plate has conventionally been made of an aluminum alloy. This perforated plate made of aluminum alloy is manufactured by punching, drilling, or the like, followed by press forming, stretch forming, burson forming, or the like into an engine nacelle shape.

[0003] By the way, when an airfield has been in a seaside area or an aircraft that frequently flies over the sea, the engine is often subjected to winds containing a large amount of salt, and the metal engine nacelle has a problem of corrosion due to salt damage. Have been watched. Therefore, in recent years, a composite engine nacelle has been developed instead of metal (aluminum alloy) for the purpose of weight reduction and improvement of corrosion resistance. However, the process of manufacturing a composite perforated plate is difficult, and so far, a method of forming a composite material into a nacelle shape and hardening it and then drilling (still mainstream in the world), plastics with a large number of drilling pins A method has been employed in which a pin plate made of a porous material is pierced into a composite material before curing and then heated and cured to form a perforated plate. Recently, there has also been introduced a method in which an uncured composite material (prepreg) is preheated until the resin flow deteriorates, punched in a flat plate state by punching, and then formed into a curved mold and heat cured. .

[0004] However, the method of drilling a hole after forming and hardening the composite material into a nacelle shape requires time and expense, and it is difficult to process the formed product if it is a three-dimensional contour product. An NC control drill machine is required, and the introduction and maintenance of the machine become difficult. In addition, a method in which a plastic pin plate is pierced into a composite material before curing and then heat-cured to form a perforated plate requires that the pin plate be manufactured in accordance with a three-dimensional contour, and the plate is manufactured in a long time. And costly. In addition, in this method, it is necessary to spray blast particles on the perforated plate after removing the pin plate to scrape off the resin clogged in the holes. When the resin is scraped off by the blast powder, the surface around the hole is also cut off at the same time, and there is a problem that the shape and size of the hole cannot be maintained. Furthermore, the prepreg is preheated, punched in a flat plate state with a punch, and then molded into a curved mold and then heat-cured. It will be difficult to do.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention eliminates the above-mentioned problems of the prior art, and
The perforated prepreg perforated face plate is easily shaped and attached to the curved mold, and the holes in the prepreg perforated face plate are not blocked by the resin in the prepreg during curing by heating and pressurization. An object of the present invention is to provide a method for manufacturing a perforated plate for an aircraft engine nacelle sound absorbing panel having good holes.

[0006]

According to the present invention, there is provided a method for manufacturing a perforated panel for an aircraft engine nacelle sound-absorbing panel, which comprises the steps of: After stacking a predetermined number,
A large number of holes are punched in the laminated prepreg face plate by punching, and then the laminated prepreg porous face plate is shaped and attached to a curved mold, covered with a release film having a high elongation,
Further, a bag film is covered thereover and attached to the periphery of the curved surface forming mold via a sealing material. Then, the inside of the bag film is evacuated to release the release film and the bag film along the inner surfaces of the multiple holes of the laminated prepreg porous face plate. And
After that, put the curved mold into the autoclave,
It is characterized in that the laminated prepreg perforated face plate is cured by applying pressure. The “resin flow” of the resin impregnated in the reinforced fiber woven fabric of the prepreg face plate, which is difficult to flow, is defined as a JIS K7071 test method for prepreg composed of carbon fiber and epoxy resin (established on February 1, 1988, 1st.
As described in the meaning of the term (999 confirmation), it refers to the ratio of resin flowing out when cured at a predetermined temperature and pressure. The resin flow depends on the volatile content of the prepreg, the degree of curing of the epoxy resin, and the resin content. For an overview of the test method for resin flow, see JISK above.
In 7071, a laminated test piece is formed on both sides of a test piece cut out of the prepreg in the order of a porous release film, a bleeder cloth, and a release film. The test piece is cured at a predetermined pressure using a hot press heated to a predetermined curing temperature.
After curing, the resin flowing out of the test piece is removed, and the resin flow rate is calculated from the change in mass of the test piece before and after curing.

In the above-described method for manufacturing a perforated panel for an aircraft engine nacelle sound-absorbing panel, the resin impregnated in the reinforcing fiber woven fabric of the prepreg face plate, whose resin flow is less than 4.5 wt%, may be used. Preferably, the diameter of the large number of holes formed in the laminated prepreg face plate is preferably 1 mm to 3 mm in terms of sound absorbing performance. The reason is, for example, that the resin flow of the prepreg is 6 to 15 wt% (the resin flow at the beginning of the prepreg production is 15 wt%, and the resin flow after the specified period is 6% after the specified storage period of the prepreg is completed). For impregnated prepreg faceplates,
When a hole having a diameter of 3 mm is formed, the hole is closed. When a hole having a hole diameter of 2 mm is formed, the hole is reduced to 1.5 mm and the shape of the hole cannot be maintained in a circular shape.
This is because the diameter becomes smaller to 5 mm and the hole shape cannot be kept circular.

In the above-mentioned method for producing a perforated panel for an aircraft engine nacelle sound-absorbing panel, the release film having a high elongation rate covering the laminated prepreg perforated face plate arranged in the curved mold has an elongation rate of 350% and a thickness of 25 or 50 μm. FEP
A film (tetrafluoroethylene-hexafluoropropylene copolymer, which is one kind of fluororesin) is preferable, and a bag film for evacuation to cover over is preferably a nylon film having an elongation of 400% and a thickness of 50 μm. . The reason for this is that, when vacuuming is performed, the release film and the bag film can be made to follow the inner surfaces of the multiple holes of the laminated prepreg perforated plate, and the hole shape can be kept circular.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for producing a perforated plate for an aircraft engine nacelle sound-absorbing panel according to the present invention will be described with reference to the accompanying drawings. % Of the prepreg sheet material 1 shown in FIG. 1 impregnated with a resin of not more than 10% by weight and cut into a predetermined size to form a prepreg face plate 2, and a predetermined number of the prepreg face plates 2 are laminated as shown in FIG. As shown in FIG. 3, a large number of holes 3 having a hole diameter of 3 mm are formed in one prepreg face plate 2 by punching. Next, as shown in FIG. 4, the laminated prepreg porous face plate 4 is molded and attached to a curved surface forming mold 5 which is recessed downward, and as shown in FIG. 5, a release film having a high elongation rate, e.g. %
A 50 μm thick FEP film 6, and further cover it with a bag film, in this case, a nylon film 7 having an elongation of 400% and a thickness of 50 μm.
Of the nylon film 7 which is a bag film at −600 mmHg.
(−0.080 Mpa) or more, and as shown in FIG. 6, the FEP film 6 as a release film and the nylon film 7 as a bag film are provided with a multiplicity of holes in the laminated prepreg face plate 4 at a pressure difference from the atmosphere. Along the inner surface of 3,
Thereafter, as shown in FIG. 7, the curved surface forming die 5 is put into the autoclave 9 and heated under the curing conditions shown in the graph of FIG.
The laminated prepreg perforated face plate 4 is hardened by pressurization (80 ° C.) (3.0 kg / cm ² ) to obtain a perforated plate 10 for an aircraft engine nacelle sound absorbing panel as shown in FIG.

As described above, in the method for manufacturing a perforated panel for an aircraft engine nacelle sound-absorbing panel of the present invention, a large number of holes 3 are formed in the laminated prepreg face plate 2 by punching. It retains softness and adhesive strength, and is easy to mold and attach to the curved mold 5. Further, the laminated prepreg porous face plate 4 disposed on the curved surface forming die 5 is covered with the FPE film 6 which is a release film having a high elongation rate, and further covered with the nylon film 7 which is a bag film having a higher elongation rate. After being attached to the peripheral edge of the curved surface forming mold 5 via the sealing material 8 and then evacuated, the release film and the bag film extend along the inner surface of the hole 3 of the laminated prepreg perforated face plate 4 so that the resin in the prepreg does not flow. Becomes
Therefore, at the time of curing by heating and pressing in the autoclave 9,
The holes 3 of the laminated prepreg perforated face plate 4 are not closed by the resin in the prepreg, and the circular holes 3 have high dimensional accuracy.
Plate 10 for aircraft engine nacelle sound-absorbing panel
Is obtained.

In the embodiment described above, the curing conditions of the laminated prepreg perforated face plate 4 in the autoclave 9 are as shown in the graph of FIG. 8, but a resin having the curing conditions is used. This is because the prepreg face plate 2 is used as a material. What matters is the resin flow rate of 4.5%
The following prepregs are used, and curing conditions are different depending on which prepreg face plate 2 uses a resin corresponding to the conditions.
Of course, after covering the FPE film 6 on the laminated prepreg perforated face plate 4 which has been shaped and attached to the curved surface forming die 5 and further sealing it with a nylon film 7 thereon, the degree of vacuuming is not limited to any resin. It differs depending on whether the prepreg face plate 2 is used as a material.

[0012]

As can be seen from the above description, the method for producing a perforated panel for an aircraft engine nacelle sound-absorbing panel according to the present invention has a curved surface because the laminated prepreg perforated panel perforated by punching retains softness and adhesiveness. It is easy to shape and attach to the mold. In addition, the laminated prepreg porous face plate placed on the curved surface is covered with a release film with a high elongation rate, and a bag film with a higher elongation rate is further covered and sealed. The release film and the bag film are lined with the inner surface of the prepreg to form a wall into which the resin in the prepreg does not flow.
The holes in the laminated prepreg perforated face plate are not closed by the resin in the prepreg. Accordingly, a perforated plate for an aircraft engine nacelle sound-absorbing panel having a well-formed and accurate hole can be obtained. In addition, in the production method of the present invention, since unnecessary auxiliary materials such as blast particles for blast processing which have been conventionally performed are unnecessary, auxiliary material costs are unnecessary, and furthermore, the resin whose pores are closed by the blast processing is reduced. Since there is no need for the removal operation, the time and cost required for the production can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a state in which a prepreg sheet material is cut to obtain a prepreg face plate.

FIG. 2 is a diagram showing a state in which a plurality of prepreg face plates are stacked.

FIG. 3 is a view showing a state in which a number of holes are formed in the laminated prepreg face plate of FIG. 2;

FIG. 4 is a diagram showing a state in which the laminated prepreg perforated face plate of FIG. 3 is shaped and attached to a curved surface forming die.

FIG. 5 is a view showing a state in which a release film is covered on the porous prepreg porous face plate on the curved mold of FIG. 4, a bag film is further covered thereover, sealed, and vacuum is drawn;
It is AA sectional drawing of.

FIG. 6 is a partially enlarged view showing a state in which a release film and a bag film are arranged along the inner surface of a hole of a laminated prepreg porous face plate by vacuum evacuation.

FIG. 7 is a view showing a state in which the laminated prepreg perforated face plate in the state of FIG. 6 is put into an autoclave together with a curved mold.

FIG. 8 is a graph showing curing conditions for a laminated prepreg perforated face plate in the autoclave of FIG. 7;

9 is a diagram showing a perforated panel for an aircraft engine nacelle sound absorbing panel obtained by being cured by heating and pressing in the autoclave of FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 prepreg sheet material 2 prepreg face plate 3 many holes 4 laminated prepreg perforated face plate 5 curved mold 6 release film (FEP film) 7 bag film (nylon film) 8 sealing material 9 autoclave 10 perforated plate for aircraft engine nacelle sound absorbing panel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02C 7/00 F02C 7/00 D 7/24 7/24 B // B29K 101: 10 B29K 101: 10 105 : 08 105: 08 B29L 31:30 B29L 31:30

Claims (3)

[Claims] After laminating a predetermined number of prepreg face plates impregnated with a resin that is difficult to flow into a reinforced fiber woven fabric, a large number of holes are formed in the laminated prepreg face plates by punching, and then the laminated prepreg perforated face plate is laminated. Is applied to a curved mold, covered with a release film with high elongation, covered with a bag film from above, attached to the periphery of the curved mold via a sealing material, and then the bag film is evacuated. The mold release film and the bag film are aligned along the inner surface of the multiple holes of the laminated prepreg perforated plate, and then the curved surface forming mold is placed in an autoclave, and then heated and pressed to harden the laminated prepreg perforated plate. Of manufacturing a perforated plate for an aircraft engine nacelle sound absorbing panel. 2. The method for manufacturing a perforated panel for an aircraft engine nacelle sound absorbing panel according to claim 1, wherein the resin impregnated in the reinforcing fiber woven fabric of the prepreg face plate has a resin flow of 4.5 wt% or less. It is resin and the hole diameter of many holes drilled in the laminated prepreg face plate is 1 mm to 3 m
m. A method for producing a perforated plate for an aircraft engine nacelle sound-absorbing panel, the method comprising: 3. The method for manufacturing a perforated panel for an aircraft engine nacelle sound-absorbing panel according to claim 1, wherein the release film having a high elongation rate covering the laminated prepreg perforated face plate disposed on the curved mold has an elongation rate of 350. 25% or 50% in thickness
μm FEP film, and a bag film for evacuation to cover over is 400% elongation and 5% thick.
A method for producing a perforated plate for an aircraft engine nacelle sound-absorbing panel, comprising a nylon film of 0 μm.