A method of manufacturing a multi-holed surface plate made of a composite material

Abstract: A method of manufacturing a multi-holed plate made of a composite material (8) wherein a molding resin (2) is filled, with a resin membrane (11) being applied inbetween, in the previously prepared holes (4) of a raw forming element of the composite material (3) and the raw forming element of the composite material (3) is hardened by heat and pressure.

Description: BACKGROUND OF THE INVENTION: Field of the invention: The present invention relates to a manufacturing method of a multi-holed surface plate made of a composite material applied-to aircraft engine nacelles, etc. where a lighter weight is required. Description of the Prior Art: In manufacturing of a multi-holed surface plate of a composite material, some measure to provide through-holes on the surface of the plate is necessary. A known method of making holes by use of drills or mechanical punches, after a raw forming element of a composite material (hereinafter referred to as "prepreg") is hardened and formed as a product, needs relatively long working time and expenses, and moreover such form as a product makes it more difficult to work. As a measure to solve this problem, the specification of the Japanese laid-open patent application No. Sho 47(1972)-2131 discloses a manufacturing method of a multi-holed reinforced plastic element including a process for hardening plastics contained in a sheet wherein a forming jig, having a back side surface and an open side surface and having a plurality of studs jutted and arranged with a space each other on the open side surface, each stud being sharpened on its point, is provided and a partially hardened sheet impregnated by reinforced plastics is put on the studs and is so pressed as to be pierced by the studs and then the plastics contained in the sheet is hardened while the sheet is kept pressed. But in this method also, it is necessary to prepare a special forming jig for each form of product, thus this method was found not necessarily advantageous from the view point of cost of work. A high-temperature resistant perforated polymer composite material and a method for making the same is disclosed in WO-A-9 322 128. This method includes partially curing polymer composite material to a visco-elastic state without inducing complete cure. In this state the polymer composite material is formed or perforated by boring, drilling or a die punching process and then finally cured. SUMMARY OF THE INVENTION: In view of the present level of the art for manufacturing a multi-holed surface plate of a composite material, it is therefore an object of the present invention to provide an improved method by which disadvantages in reducing manufacturing costs, such as making holes with much work time and expenses after forming of composite material surface plate or preparing special forming jigs even in case of manufacturing a multi-holed surface plate by making holes simultaneously with forming of a surface plate of a composite material, are improved and multi-holed surface plates are manufactured in a simplified way and with less expenses. To solve this object the invention provides the method defined in Claim 1. The present invention relates to a manufacturing method of a multi-holed surface plate made of a composite material by use of a prepreg having previously prepared holes, wherein a molding resin is filled, with a resin membrane being applied inbetween, in the previously prepared holes of a raw forming element of the composite material consisting of reinforcing fibers and matrix resins and the raw forming element of the composite material is hardened by heat and pressure. The prepreg previously holed by mechanical punches, etc. consists of a reinforcing cloth woven by glass fibers or carbon fibers, etc. and'of matrix resins like epoxy resins, etc. The holes of the prepreg are previously filled, or filled and hardened, with molding resins like a half-hardened silicone rubber of sheet or a natural temperature hardening type silicone resin, with a resin membrane being applied inbetween, thereby the matrix resin in the prepreg, if melted, is prevented to flow into the holes and to block them. The prepreg so prepared is heated and hardened for forming and completed as a multi-holed surface plate, with the holes being kept as they are, after the molding resin and the resin membrane are taken off. Further, in the present invention, in order to fill the molding resin in the holes of the raw forming element of the composite material, the molding resin is covered by a breather made of a woven stuff and thereby the vacuum exhaustion for filling the molding resin into the holes of the raw forming element of the composite material can be surely performed. The molding resins used for practice of the present invention can be selected, in addition to the silicone resin as mentioned above, from such thermosetting resins as epoxy resin, polyester resin, etc. or such thermosetting resins as polyethylene resin, nylon resin, vinyl resin, etc. Further, as for the resin membrane, such as made of silicone resin, polyfluoroethylene or polyethylene can be used: The materials of these molding resins and resin membranes are selected according to the temperature of heating and hardening. DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Fig. 1 is an illustrative drawing showing holes of a prepreg used in the method of the present invention. Fig. 2 is an illustrative drawing showing a status of a molding resin being applied and hardening by an autoclave being prepared according to a preferred embodiment of the present invention. Fig. 3 is an illustrative drawing showing a process to take off a molding resin after hardening according to a preferred embodiment of the present invention. Fig. 4 is an illustrative drawing showing a status of a multi-holed surface plate of a composite material after formed according to a preferred embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS: Now the preferred embodiments of the present invention will be described with reference to the accompanying drawings. As shown in Fig. 1, a prepreg 3 in which a woven stuff is used as reinforcing fibers (reinforcing fibers: glass fibers, carbon fibers, silica fibers, alumina fibers, etc. and matrix resins: epoxy resin, bismaleimide resin, polyester resin, phenol resin, polyimide resin, etc.) is laid in two layers and is applied to, on its both surfaces, by a plastic film 5 made of a fluororesin which is good in the mold releasability, for the purpose of preventing dust sticking at the time of mechanical punching. The prepreg is then holed by mechanical punching and set on a forming jig 1. In this Fig. 1, the plastic film applied on the side of the forming jig 1 has been already taken off. Then, as shown in Fig. 2, as a first step for preparation of hardening, the hold prepreg is covered by a resin membrane 11 and a half-hardened silicone rubber of sheet as a molding resin 2 is put thereon, and then a breather 6 made of a woven stuff of glass fibers or nylon fibers is applied to for the purpose of securing good vacuum exhaustion. As for a resin membrane 11, a fluororesin is suitable as it has a good break stretchability, tear strength and mold releasability. As for the thickness thereof, the thinner is the better for good fitting to the holes and a thickness of 5 to 120 µ can be selected and utilized according to the diameters of the holes. In this embodiment, a resin membrane of 11 µ thickness is used for the holes 4 of a 2 mm diameter each. A nylon bag film 7 being put thereon, a sealing is made by sealant tapes so as to prevent air leakage between the forming jig 1 and the nylon bag film 7 and the air is exhausted by use of vacuum from a vacuum exhaustion port 10. 60 minutes thereafter, a molding resin 2 is filled in the holes 4 of the prepreg 3, with the resin membrane 11 being applied inbetween, thus a measure to prevent the matrix resin of the prepreg 3 to flow into the holes is prepared. Then, the prepreg so prepared for forming is hardened in an autoclave. In this preferred embodiment, the pressure of about 3.5 kg/cm 2 , the temperature of 180°C and the heating for about 2 hours are applied. After finishing of hardening, the temperature and the pressure are lowered and the nylon bag film 7 is taken off. Then, the hardened molding resin 2 is taken off as shown in Fig. 3. The hardened molding resin 2, being bonded with the breather 6 by adhesive, can be taken off from the prepreg 3 together with the resin membrane 11 and the plastics film 5 without being torn. After this, the hardened prepreg 3 is taken up from the forming jig 1 and a multi-holed surface plate made of composite material 8 becomes complete, as shown in Fig. 4. According to the manufacturing method of a multi-holed surface plate made of a composite material and the prepreg pursuant to the present invention, a multi-holed surface plate made of a composite material can be made without the holes of the prepreg being blocked by the flow of a resin while the prepreg is being hardened. Further, according to this manufacturing method, neither an expensive forming jig nor a preparation of special jigs and tools is necessary and thereby the manufacturing costs can be reduced. Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims: A method of manufacturing a multi-holed surface plate made of a composite material (8), characterized in that previously prepared holes (4) in a raw forming element of composite material (3) consisting of reinforcing fibres and matrix resin are filled with a moulding resin (2), a resin membrane (11) being applied between said forming element (3) and the moulding resin (2), whereafter the raw forming element of the composite material (3) is hardened by heat and pressure. The method of manufacturing a multi-holed surface plate made of a composite material (8) according to claim 1, characterized in that the molding resin (2) to be filled in the holes (4) of the raw forming element of the composite material (3) is a half-hardened silicone rubber. The method of manufacturing a multi-holed surface plate made of a composite material (8) according to claim 1, characterized in that the molding resin (2) to be filled in the holes (4) of the raw forming element of the composite material (3) is a silicone resin of natural temperature hardening type. The method of manufacturing a multi-holed surface plate made of a composite material (8) according to claim 1, 2 or 3, characterized in that the molding resin (2) to be filled in the holes (4) of the raw forming element of the composite material (3) is covered by a breather (6) made of a woven stuff. The method of manufacturing a multi-holed surface plate made of a composite material according to claim 1, 2, 3 or 4, characterized in that the holes (4) are made in the raw forming element of the composite material by mechanical punching.

Inventors: NISHIYAMA SHIGERU, SAITO KOUICHI, YAMAMOTO TETSUYA, NISHIYAMA, SHIGERU, SAITO, KOUICHI, YAMAMOTO, TETSUYA, NISHIYAMA, SHIGERU, C/O NAGOYA AEROSPACE SYS.WORKS, SAITO, KOUICHI, C/O CHURYO ENGINEERING K.K., YAMAMOTO, TETSUYA, C/O NAGOYA AEROSPACE SYS. WORKS
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1995
Main classification: B29C33
IPC codes: B29C39, B29C33, B29K105, B29L7, B29C70, B29C43, C08J5