Patent Description:
Usually, the interior of an airplane is separated into different areas by airplane frames. Different areas are used as passenger cabins, cargo cabins, etc. In order to match a streamlined profile of an airplane, the airplane frame typically has a mutually angled and arc-shaped configuration shown in <FIG>. An annular frame formed by splicing together a plurality of arc-shaped airplane frames forms supporting components of individual separated areas.

Composite materials have the characteristics of light weight and high structural strength. Frames made of composite materials have become a dominant form of airplane frames. Generally, the airplane frame needs to go through the following steps: laying braided fiber prepreg on a mold with a shape corresponding to the airplane frame, pressurizing and reinforcing sealingly with a vacuum bag, and demolding.

In conjunction with <FIG>, after laying the braided fiber prepreg on the corresponding mold, since the frame with arc-shaped configuration has different arc lengths at the positions corresponding to the inner arc and the outer arc, significant wrinkles will be produced at the curved positions after curvedly laying conventional fiber bodies, which will seriously affect the quality of the formed frame.

Boeing Company of the United States also disclosed a manufacturing process of using dry fiber braiding combined with RTM molding. According to this manufacturing process, airplane manufacturers need to keep braids on braiding mandrels, transport them to the assembly workshop, and then remove and assemble them. Therefore, this kind of manufacturing process requires manufacturers to purchase more braiding mandrels and results in higher transportation costs for transporting braiding mandrels.

<CIT> describes a method for manufacturing a curved structural element made of composite material with a complex, open cross-section. The process involves preparing multiple flat components with layers of curved and straight fibers infused with resin, hot-forming these components, and assembling them on a shaped, inflatable device. The assembly is then subjected to a polymerization cycle in an autoclave, where the inflatable device applies pressure from inside the C-shaped component.

Directed to the above-mentioned shortcomings of the method of manufacturing an airplane frame according to the prior art, one of the objects of the present disclosure is to provide a method of manufacturing an airplane frame that is capable of effectively avoiding wrinkles formed in the fiber body laying process.

The object is achieved by way of the following form of manufacture of the present disclosure. The airplane frame has an arc-shaped structure and comprises a Z-shaped cross-section, and comprises flanged areas positioned at two side edges in the lateral direction, bent areas located adjacent to said flanged areas, and a web area extending between said bent areas, wherein said bent areas have an arc-shaped structure, and said web area is an annular sector in shape. Said method comprises the following steps:.

The present disclosure utilizes the characteristic that fibers are easy to curve following the shape, braides fibers along the extension direction of the arc-shaped structure of the airplane frame, and can effectively solve the problem that wrinkling problem occurring when curvedly laying an annular sector shaped web.

According to the invention, said web area is formed by using a biaxial braiding method.

According to the invention, any one of said two flanged areas is formed by using a triaxial braiding method.

According to a preferred embodiment of the present disclosure, one of said two bent areas is a first bent area formed by using a triaxial braiding method, and at least one second fiber body is continuously extended along the length direction of the frame in said first bent area. Preferably, the extending length of said second fiber body is not less than half of the extending length of said first bent area, in an extension direction of said first bent area. More preferably, the extending length of said second fiber body is equal to the extending length of said first bent area, in an extension direction of said first bent area. Providing second fiber bodies extending continuously in bent areas can ensure that the combined airplane frames of the present disclosure have a good tensile strength in the circumferential direction after joining the airplane frames of the present disclosure into an annular shape.

According to a preferred embodiment of the present disclosure, said first bent area is an inner bent area located at the inner position of the annular sector of said web area, and the flanged area locating at the inner position of the annular sector of said web area is formed by using a triaxial braiding method. By providing the first bent area and the flanged area formed by using a triaxial braiding method at the inner side of the web area, the first bent area and the flanged area have a smaller circumferential extending length (corresponding to the inner arc length of the annular sector shaped web area), which is beneficial to improving the tensile strength and compression strength of the first bent area and the flanged area. On the other hand, forming the first bent area and flanged area at the inner position of the web area formed by using a triaxial braiding method instead of a biaxial braiding method can further improve its tensile strength and compression strength.

According to a preferred embodiment of the present disclosure, after said prepreg is formed, an isolation paper is affixed to said prepreg, and the prepreg is separated from said braiding mandrel for winding collection. After performing a specific braiding method, the braid keeps fiber bodies on the braid in the desired extending direction without needing to be held by a braiding mandrel. On this basis, by separating the braid from the braiding mandrel after forming the prepreg by preimpregnating, the braiding mandrel can be kept in the braid manufacturing workshop and used continuously; and the braid prepreg wound as a roll is also easy to transport.

The present disclosure also relates to an airplane frame manufactured using any of the manufacturing methods described above.

The above preferred embodiments can be combined in any way to obtain each preferred example of the present disclosure, insofar as it is not contrary to common knowledge in the art.

As mentioned above, the present disclosure proposed an entirely new method of manufacturing a Z-shaped airplane frame, which utilizes braiding technology to solve problems in curved laying; and by manufacturing a braid into a prepreg using preimpregnating technology, problems in shape retaining transportation and subsequent glue injection process of three-dimensional dry fiber braids are avoided. In addition, according to the present disclosure, weaves fibers of <NUM>° are simultaneously braided into a whole layer in the flanged areas, improving the mechanical properties of parts.

Other systems, methods, features and advantages of the present disclosure will be understood by those skilled in the art upon reading the following accompanying drawings and detailed descriptions. It is intended that all such additional systems, methods, features and advantages are included in this specification and in the contents of the present disclosure, and are included within the scope of the present disclosure and are protected by the appended claims.

For a better understanding of the above and other objects, features, advantages and functions of the present disclosure, reference may be made to preferred embodiments illustrated in the accompanying drawings. Throughout the drawings, identical reference numerals refer to identical parts. It will be understood by those skilled in the art that the accompanying drawings are intended to schematically illustrate preferred embodiments of the present disclosure without any limitation on the scope of the present disclosure and that the various parts of the drawings are not drawn to scale.

Next, the inventive concept of the present disclosure will be described in detail with reference to the accompanying drawings. What are described herein are merely preferred embodiments according to the present disclosure, on the basis of which those skilled in the art may contemplate other embodiments in which the present disclosure can be implemented, which also fall within the scope of the present disclosure. In the following specific description, directional terms such as "up", "down", "inside", "outside", "vertical", "lateral" and the like are used with reference to the directions illustrated in the accompanying drawings. The components of embodiments of the present disclosure may be placed in a number of different directions and the directional terms are used for illustrative purposes and are not limiting.

<FIG> shows a three-dimensional structure of an airplane frame <NUM>. As shown in <FIG>, an airplane frame <NUM> has an overall arc-shaped structure and includes flanged areas <NUM>, <NUM> positioned at two side edges in the lateral direction (i.e. edge strip areas of the frame), bent areas <NUM>, <NUM> next to the flanged areas <NUM>, <NUM>, and a web area <NUM> extending between the bent areas <NUM>, <NUM>. The bent areas <NUM> and <NUM> have an arc-shaped structure, and the web area <NUM> is an annular sector in shape. According to the airplane frame <NUM> of <FIG>, the cross-section thereof is substantially a Z-shaped configuration as shown in <FIG>. According to the present disclosure, the airplane frame <NUM> can be made by the following steps:.

As can be seen from the above, the present disclosure utilizes the characteristic that fibers are easy to curve following the shape, braides fibers along the extension direction of the arc-shaped structure of the airplane frame <NUM>, and can effectively solve the problem that the wrinkling problem occurring when curvedly laying an annular sector shaped web.

Referring further to <FIG> and <FIG>, according to a preferred embodiment of the present disclosure, different braiding methods are employed in the web area <NUM>, the bent areas <NUM>, <NUM>, and the flanged areas <NUM>, <NUM>. For example, in the example of <FIG>, the web area <NUM>, the first flanged area <NUM> with a smaller extending height, and the first bent area <NUM> interposed between the first flanged area <NUM> and the web area <NUM> may be formed by using biaxial braiding; and for the other bent area <NUM> (the second bent area <NUM>) and the other flanged area <NUM> (the second flanged area <NUM>) with a larger extending height, a triaxial braiding method may be employed.

Preferably, a second flanged area <NUM> with a greater extending height and formed by using triaxial braiding is provided on the inner side of the annular sector shaped web area with a smaller extending length, thereby forming an inner flanged area, i.e. an inner edge strip area. The second flanged area <NUM> is used as the main stress surface of an airplane frame. A second flanged area <NUM> provided on the inner side has a shorter extending length and has a more beneficial compression strength in the height direction than a second flanged area provided on the outer side of the annular sector shaped web area, i.e. corresponding to the position of the first flanged area <NUM>.

Refer to <FIG> in conjunction with <FIG>, in which a sectional view of a braid formed by using triaxial braiding is schematically shown. In the second bent area <NUM>, at least one second fiber body S3 extends continuously in the length direction AA' of the frame in the bent areas <NUM>, <NUM>. Preferably, the extending length of the second fiber body S3 in the extending direction AA' of the bent areas <NUM>, <NUM> is not less than half of the extending length of the bent areas <NUM>, <NUM>. More preferably, the extending length of the second fiber body is equal to the extending length of the bent areas <NUM>, <NUM>. Referring to <FIG>, after a plurality of airplane frames <NUM> are combined to form an annular structure (corresponding to the annular structure inside an airplane), second flanged areas <NUM> (inner flanged areas) form an annular ring. Since each of the second flanged areas <NUM> is provided with continuously extending second fiber bodies S3, the group of annular airplane frames has better tensile strength and compression strength. In particular, for an airplane, the pressure inside the airplane cabin is much higher than the pressure outside the cabin, and according to the second fiber body described above, the airplane frame <NUM> is able to withstand the tensile force exerted on the inner side of the airplane frame due to the pressure difference.

Claim 1:
A method of manufacturing an airplane frame (<NUM>), wherein said airplane frame (<NUM>) has an arc-shaped structure and comprises flanged areas (<NUM>, <NUM>) positioned at two side edges in the lateral direction, bent areas (<NUM>, <NUM>) located adjacent to said flanged areas (<NUM>, <NUM>), and a web area (<NUM>) extending between said bent areas (<NUM>, <NUM>), wherein said bent areas (<NUM>, (<NUM>) have an arc-shaped structure, and said web area (<NUM>) is an annular sector in shape, wherein said method comprises the steps of:
according to the size of the airplane frame (<NUM>), braiding a first fiber body (S1, S2) on a braiding mandrel in an extension direction of said airplane frame (<NUM>) to form a cylindrical braid;
developing said cylindrical braid to form a planar braid;
preimpregnating said planar braid with resin to form a prepreg;
cutting said prepreg according to the size of said airplane frame (<NUM>); and
laying and curing the cut prepreg to form said airplane frame (<NUM>),
characterized in that
said web area (<NUM>) is formed by using a biaxial braiding method, and in that any one of said two flanged areas (<NUM>, <NUM>) is formed by using a triaxial braiding method.