JPH01182015A - Coreless molding and curing method of outside plating-reinforcing material composite assembly - Google Patents

Abstract

PURPOSE: To enable simultaneous hardening of an outside plate reinforcing material composite built-up body having a single outside plate form by providing a reinforcing material molding member which has both at least one ridge for molding reinforcing material and a trough formed for the corrugated hardening surface. CONSTITUTION: A plurality of strips or thin layers of composite material are placed on ridges 16 for molding reinforcing material and into the recessed parts 19. Further, the outside plate of the similar composite material is arranged in an outside plate receiving space 13 of an outside plate molding member 11 and retained by its stickiness, specific gravity and the others. Then, an expandable molding device 17 is arranged in troughs 16 and therefore arranged into a molding enclosure in which hardening surfaces of the molding members are formed. Then, air pressure is exerted to the expandable molding device. The molding member receives uniform pressure from all side faces by both heat of electric resistance of the inside and external pressure. In the case of simultaneously hardening reinforcing material 21 and the outside plate 22, the part with which the composite material comes into contact is together molded and resin is cured. A solid member is formed by mutually combining the composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel method of providing a mold for co-curing together a composite assembly of skin and reinforcement.

BACKGROUND OF THE INVENTION There is an increasing trend towards the use of so-called composite materials in the manufacture of aircraft parts. Such composite materials are typically comprised of interwoven materials formed from reinforcing fibers and unidirectional fiber materials such as glass fibers, graphite, boron, and others and impregnated with epoxy resins.

The advantage of using such materials is that they can eliminate many of the mechanical fasteners, such as heads, that are used in attaching ordinary metal panels to frameworks. At the same time, it is possible to provide a strong and lightweight structure. A typical example of the use of such skins is U.S. Pat. No. 4.39, issued June 26, 1983, to Boeing Company.
No. 5.450. However, the above-mentioned patents relate to the construction of components having reinforcing cores located between intersecting skin panels.

[Problem to be solved by the invention]

The present invention concerns a method for manufacturing a structure of the type having a single skin with stiffening stiffened integrally therewith, such as a panel, and a mold therefor. Such reinforcements are typically formed with transverse flanges to stiffen the skin and secure the skin to support the framework. However, due to the arrangement of these transverse flanges, it has not been easy to integrally mold the outer panel and the reinforcing material until now. This is because the molded composite member could not be removed from the conventional mold. The practice has therefore been to manufacture the skin and the reinforcement separately and then secure the reinforcement to the skin, typically by using adhesives under heat and pressure. Fasteners have also been used to secure such reinforcements to the skin.

Another manufacturing method has been to use expensive composite molds to hold the skin and reinforcement in place during an autoclave in order to co-cure the reinforcement and skin together. . However, such molds are very expensive, bulky and difficult to handle, and require special autoclaves capable of housing such molds.

It is an object of the present invention to provide a new method of using a mold for co-curing a composite skin-stiffener assembly with a skin and reinforcement made of reinforcing fiber material impregnated in a resinous material. There is a particular thing.

Another object of the present invention is to develop a new method for the integral simultaneous curing of composite skin-reinforcement assemblies of fiber materials and resins, which allows improved heating and simultaneous curing without autoclaving. It is about providing.

Another object of the present invention is to cure the outer panel and the reinforcing material integrally,
The object is to provide a method and molding apparatus that thereby avoids the need for joints or mechanical fasteners to join them.

Another object of the invention is to co-cure the skin in one piece for a structural component with an open cross-section, with a spaced gap between the elements, so that the skin for the structural component has a It is an object of the present invention to provide a method and a molding apparatus that are accessible and easy to inspect and repair.

Another object of the present invention is that by positioning and curing all of the composite materials in pressure contact engagement with corresponding hardened surfaces of the molded member, the novel method and molding apparatus of the present invention provide smooth outer surfaces and The aim is to produce a smooth inner surface.

Another object of the invention is a type of skin with a single skin.
A method of using a mold for curing a composite reinforcement assembly, the expansible molding comprising a piece of composite material disposed within a molded enclosure in alignment with a spaced gap between the reinforcement forming materials. It is an object of the present invention to provide a method in which the expansible molding device is held in place under pressure by the device so that it can be removed by withdrawing the device through a spacing gear.

[Means to solve the problem]

SUMMARY OF THE INVENTION In its broadest aspect, the present invention provides a reinforcement molded member having at least one reinforcement molding ridge and a valley formed relative to a corrugated hardened surface. The present invention provides a molding method for curing a single skin type composite skin-stiffener assembly including the steps of preparing a single skin type composite skin-stiffener assembly. Multiple thin layers of composite material are deposited onto the corrugated stiffening surface in the form of open cross 5 section reinforcements.

An expandable molding device is provided in the valley adjacent to the ridge of the reinforcement molding member upon which the plurality of thin layers of composite material are disposed. A composite skin is also placed onto the hardened surface of the skin molding.

The hardened surfaces of the skin molded member and stiffener molded member are then juxtaposed such that at least a portion of the skin on the skin molded member is in contact with at least a portion of the composite material on the edge of the skin molded member. Define the upper molded enclosure. The expandable molding device is then expanded to apply pressure against the skin and the composite material on the ridges to hold them in place.

The skin and reinforcement composites are then co-cured under appropriate heat and pressure. After curing, the expandable molding device is removed by pulling through a corresponding spacing gap provided between pieces of composite material each placed on an adjacent rim.

According to a further aspect of the invention, heating elements are embedded in the molded member to provide adequate heat to the composite material of the skin and reinforcement.

According to another feature of the invention, a mold is provided for co-curing a composite reinforcement assembly. The mold includes a skin molding member having a skin-receiving hardened surface. A reinforcement molding member is also provided and has a hardened surface including at least one reinforcement molding ridge and valleys on opposite sides of each ridge. These molded parts are held during operation with the hardened surfaces juxtaposed. An expandable molding device is positioned in each valley and presses the skin composite material against the cured surface of the skin molding member and against the ridges of the reinforcement molding member during the heat curing cycle. It will be done like this.

〔Example〕

Preferred embodiments of the invention will now be described with reference to examples illustrated in the accompanying drawings.

Referring now to the accompanying drawings, particularly FIGS. 1 and 2, there is shown a molding according to the present invention for co-curing a composite skin-stiffener assembly such as shown at 9 in FIG. The overall structure of the device is indicated at 10. This molding device essentially consists of an outer panel molding member 11 and a reinforcement molding member 1.
2. Both of these molded parts are provided with hardened surfaces 11" and 12". These molded parts are secured to each other by conventional coupling means, such as hinges (not shown) or the like, thereby hardened surface 1
1' and 12' are arranged side by side.

As shown more clearly in FIG. 1, the skin bottom mold member 11 has a skin receiving cavity 13 formed in its hardened surface 11'. The skin receiving cavity is an elongated flat shallow cavity adapted to hold a plurality of thin layers of fibrous material impregnated with resin material.

The reinforcing material molding member 12 is provided with reinforcing material forming ridges 14 and 15 on its hardened surface 12', which are formed by machining or the like on the reinforcing material molding hardened surface.

These ridges 14,15 have a flat top surface 23 and side walls 23' angled with respect to the top wall 23, forming substantially inverted trough-like structures. A zone is defined to thereby facilitate withdrawal of the cured composite skin-stiffener assembly. ridge 14
．． A cavity or valley 16 is defined between 15 and adapted to receive therein an expandable molding device, here shown in the form of an inflatable membrane 17. This membrane is typically configured to expand against each of the walls surrounding the valley 16 and against the facing skin facing the valley when the mold is closed.

Molding members 11 and 1 are used to apply heat to specific areas surrounding the mold cavity and to the skin.
A heating tube or heating element 18 is arranged inside each of 2 . This heating medium is constituted, for example, by electrically resistive elements embedded in the molded part or by conduits in which the heating fluid circulates. These elements or tubes are placed in the area where the resin-impregnated fiber material is to be co-cured. This simultaneous curing may be accomplished by heating all hardening surfaces of the mold.

In the embodiment shown in FIGS. 1 and 2, a flat recess 19 is arranged in the valley 16 adjacent to each of the ridges 14, so that the flange 2 of the reinforcement
0 is observed.

The operation of this forming apparatus or the method carried out by this forming apparatus comprises forming a plurality of strips or thin layers of composite material.
The reinforcing material is placed on the ridge 14 and into the recess 19.

A similar composite skin is also placed in the skin receiving cavity 13 of the skin molding member 11 and held thereon by its own adhesion, gravity, or by other suitable means such as suction or the like. be done. Then the expandable molding device 17
6, and thus placed in a molded enclosure formed by juxtaposition of the hardened surfaces of the molded parts.

A pump (not shown) then applies air pressure to the inflatable molding device. This air pressure forces the expandable membrane against the composite material, holding it in place and under the desired pressure. Heat and external pressure are then applied to the molded member to maintain equal pressure from all sides. When the reinforcing material 21 and the skin 22 are simultaneously cured, the parts where the composite materials are in contact, such as the flat top surface 23 of the ridge 15 and the surface of the skin molded member adjacent thereto, are - By performing molding together and applying heat and pressure to harden the resin at the relevant portions, the composite materials are bonded to each other to form a solid member. Heat and internal and external pressures are applied for a predetermined period of time specified by the curing cycle for the composite material used, after which time the mold is cooled and opened. The reusable expandable molding device 17 membrane is deflated and removed through a space or spacing gap intermediate the free ends of the laterally oriented stiffener attachment flanges 20.

FIG. 4 shows a product formed using a mold according to the type of process described with respect to FIGS. 1 and 2. FIG. As shown here, this product is used in the construction of an aircraft wing 30 such as that shown in FIG. Note that FIG. 4 is a sectional view of the blade in FIG. 3 taken along line 4-4 in the direction of the arrow. It can be seen that in this type of wing construction, virtually no fasteners are required on the outer surface of the wing.

Reference is now made to FIG. 5, which illustrates typical modifications that may be made to the composite skin-stiffener assembly. The stiffener 31 shown in this particular embodiment is formed with passages 32 for attaching transverse ribs 33 extending laterally. The cross ribs are shown here as inverted T-shaped ribs, also made of composite material, with mold pressure pads 34 on either side. It is also observed in this particular embodiment that the ridges of the reinforcement are formed with a reduced height at the location 35 in the area of the passageway 32. Of course, various other design changes are possible.

Figures 6A and 6B show molded parts 11'' and 12''°.
shows another shape of . As shown here,
The outer plate molding member 111 has a cylindrical shape, and can also be formed in pieces. The stiffener molded member 12'' is formed from a plurality of molded sections having laterally spaced ridges 40. An inflatable molded device is formed into each molded enclosure 42 defined between the ridges 4o. These molds are used in the construction of tubular airplane fuselages.

The molded parts 11 and 12 so far described were equipped with embedded heating means, but these molded parts could be placed in an autoclave to carry out the heating and required pressurization for the curing cycle. It is also possible to do so. However, it is more economical to provide the heating means as described herein. This is because it is possible to perform curing at the same location where the dough is placed in the mold.

〔Effect of the invention〕

With special methods and associated molds as described above, the reinforcement may have different dimensions, thicknesses or widths;
It will be appreciated that it may also be configured as desired. It is not necessary that the reinforcements run parallel to each other, so there is substantial freedom in their placement. No trimming of the skin or reinforcement is necessary even after curing, and flat or contoured structures can be molded. Cross ribs can also be incorporated into the co-cure, and by co-curing the skin and stiffeners together, no mechanical fasteners or secondary adhesive bonds are required. Not only those necessarily limited to the structure of the aircraft itself, but also flooring, wall materials, ceilings, etc.
It is also possible to manufacture complete bodies for the construction of various aircraft parts or elements.

It is intended to include obvious modifications of the preferred embodiments described herein that are within the scope of the invention if such modifications fall within the scope of the claims.

[Summary of the invention]

Finally, to summarize the invention for ease of understanding, the invention is a method of using a mold to cure a composite skin-stiffener assembly from a resin-impregnated fibrous material. This method allows coreless molding and simultaneous curing of single-skin type panels with integral reinforcement, allowing the use of reinforcement of various heights, thicknesses, and widths. This allows the layout of the reinforcing members to be substantially free, and also enables cross-reinforcing members to be integrally formed.

No adhesives or mechanical fasteners are required. The method also includes preparing a molded member for reinforcement formation having a corrugated surface, placing the composite material onto the ridges defined by the corrugated surface, having an open cross-sectional shape and spaced apart from each other. The method further comprises forming the gapped stiffener into bonding contact with the skin-forming material and co-curing the skin-stiffener assembly.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a mold for co-curing a composite skin-stiffener assembly according to the method of the present invention; FIG. 2 shows a thin layer of composite material placed on a molded part. An enlarged sectional view; FIG. 3 is a plan view of a portion of an aircraft wing constructed with a composite skin-stiffener assembly according to the present invention; FIG.
Figure 5 is a partial cross-sectional view of the composite skin-stiffener assembly showing the passage of the cross-ribs over the reinforcement in suitable forming equipment; Figure 6A is used during fuselage construction. a partial cross-sectional view of a cylindrical mold used to mold a composite skin-stiffener assembly;
and FIG. 6B are partially enlarged views of FIG. 6A. 9-Outer panel-reinforcing material composite assembly 10-Molding bag W11, 11" - Outer panel molding member 11"
- Skin hardened surface 12, 12" - Reinforcement molded part 12' - Corrugated hardened surface 13 - Skin receiving cavity 14.1
5, 4 (1---Ridge for forming reinforcing material 16-Trough 17
- expandable molding device 18 - heating element 19 - recess
20- Flange 21. 31- Reinforcement material 22- Outer plate 23- Top surface 23
'-Side wall 30-Wing 32-Passway 33-Cross rib
34-Pressure pad

Claims (1)

Claims: 1. A method of forming and curing a composite skin-stiffener assembly of the single skin type, comprising: i) at least one stiffener forming ridge formed on each side of each ridge; ii) providing a stiffener molded member having a corrugated hardened surface formed with valleys; ii) placing a piece of stiffener-forming composite material over each ridge, facing each side of the ridge; forming a reinforcement on the ridge with an open cross-sectional configuration and a spacing gap between the placed reinforcement-forming composite pieces; iii) corrugation hardening of the reinforcement molded member; placing an expandable molding device in each of the valleys formed by the surfaces over the gaps between the pieces of reinforcement-forming material placed; iv) onto the skin hardening surface of the skin molding member; and placing a composite skin; v) said valley defining a longitudinal molded enclosure along each side of each of the ridges, and at least a portion of the skin material on the skin molded member each The skin hardened surface of the skin molded member and the corrugated stiffener hardened surface of the stiffener molded member are in molded contact with at least a portion of each of the reinforcement forming composite material pieces placed on the ridges of the skin. vi) applying an appropriate molding pressure to the skin material and the reinforcement-forming composite material extending into the molded enclosure to cause them to move in that position against the corresponding hardened surfaces; vii) curing the skin and reinforcement composite under suitable heat and pressure; 2. The corrugated hardened surface of the reinforcement molded member forms a plurality of molded ridges and valleys, step (iii) placing an inflatable membrane in each of the valleys of the longitudinal molded enclosure and applying air pressure to the membrane. 2. The method of claim 1, comprising adding. 3. The ridge is an elongated ridge, and the step (
ii) longitudinally placing a strip of composite material over a portion of the forming ridge and an adjacent valley portion, the strip extending along the valley portion forming a skin; defining a lateral flange spaced from the material;
The method according to claim 2. 4. The method of claim 3, comprising forming a valley with a flat recess and placing the strip of material over the flat recess to form the lateral flange. 5. A method according to claim 1, 2 or 3, comprising placing the strip of material on an inverted trough-shaped ridge. 6. The method of claim 1, comprising shaping the ridge with a flat top to define a contact portion for flat surface engagement with skin material. 7 forming a portion of the ridge with a reduced height to define a lateral cross-rib passageway, and laterally placing the cross-rib through the cross-rib passageway over the reduced height portion; 2. The method of claim 1, including co-curing the cross ribs integrally with the skin and the stiffener in bonding contact with a stiffener-forming material. 8. The method of claim 1, wherein step (vii) comprises providing heating elements to the reinforcement molding and skin molding to apply regulated heat to effect the simultaneous curing. 9 A skin molding member having a skin hardening surface; a reinforcement molding having a wavy hardening surface formed with at least one reinforcement molding ridge and valleys formed on both sides of each reinforcement molding ridge. the skin molding member and the reinforcement molding member are brought together in close proximity such that the skin hardened surface faces the corrugated hardened surface; and in a position opposite the hardened surfaces on both sides during the curing cycle. in each valley between the stiffening surfaces to apply pressure to hold the composite skin on the stiffening surface of the skin molding member and on the ridges of the reinforcement molding member. and an expandable molding device.
A mold for forming and curing a single skin style composite skin-stiffener assembly. 10. The mold of claim 9, wherein the hardened surface of the reinforcement mold member is formed with a plurality of molding ridges and valleys. 11 The molding ridges are elongated ridges, and adjacent each of the ridges the valley is provided with a flat recess to define reinforcing lateral flanges spaced from the integrally molded skin. Claim 10 The method is adapted to be molded.
The mold described. 12 the ridge is a substantially inverted U-shaped cross-section defining a flat top wall and angular side walls to the top wall, defining an inverted supra-trough ridge; ,
The mold according to claim 11. 13. The mold of claim 10, wherein a plurality of heating elements are arranged on the skin and reinforcement molding elements for heating them. 14 on at least one side constructed and arranged to position a composite cross rib in each of the cross rib passages so as to be in co-curing contact with a composite reinforcement disposed on the ridge; 13. The mold of claim 12, having at least one portion of reduced height defining a lateral cross-rib passage.