JP2011224989A - Sandwich panel with multiple-order curved surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sandwich panel with a multiple-order curved surface that is adapted to form an inner and outer complex structure of a second or third order curve, is adapted to form a relatively thick plate without any change thereby reducing machining cost, is adapted to adjust the inner structure according to loads, thereby reducing weight, is adapted to existing equipment, and can be manufactured more easily and simply than a conventional manufacturing method.SOLUTION: The lightweight and inexpensive sandwich panel having a multiple-order curved surface can be easily manufactured by separately forming a hollow core A by a laminate molding method in advance, and joining surfaces 1 and 2 to the front face and rear face of the multiple-order curved surface having greatly different shapes, to prevent harmful deformation such as buckling and corrugations. In particular, the lightweight and inexpensive hollow core A having the outer and inner complex structure can be simply formed by forming the hollow core A by the laminate molding method.

Description

The present invention relates to a quadratic or cubic complex curved sandwich panel. That is, it consists of a hollow core material formed into a honeycomb shape or polyhedral aggregate by a layered modeling method such as stereolithography or powder molding method, and front and back plates such as fiber reinforced plastic, etc. as various structures The present invention relates to a sandwich panel for forming a curved curved surface used for curved surface molding.

The structure of a sandwich panel used for a structural member of a conventional aircraft or the like is a laminate in which face plates 10 and 11 such as aluminum and fiber reinforced plastic are bonded to both front and back surfaces of a honeycomb core D having a flat plate shape as shown in FIG. It is.

Usually, in order to avoid harmful deformation at the time of molding, it is formed into a flat surface as shown in FIG. 6, but when forming into a curved surface, the honeycomb core C is cut into a curved surface in advance as shown in FIG. Many processes are required, such as pressurizing the curved surface, which increases the cost. Moreover, even in the case of a curved sandwich panel manufactured by such a method, the honeycomb core is mainly made of paper-derived materials such as Nomex and Aramid, so the rigidity to maintain the honeycomb-shaped internal hollow structure is low, and the face plate The cell wall forming the hollow structure is deformed by the pressure applied at the time of joining to the plate, and a harmful irregular surface such as buckling or wrinkle occurs on the face plate after molding, the predetermined shape cannot be molded, and the strength and A problem of yield reduction due to a decrease in rigidity occurs.

Furthermore, in order to prevent the occurrence of buckling and wrinkles, a flat core material is used, so the surface shape and the back surface shape must be approximately parallel with the thickness of the core material separated, such as a conical shape. It was difficult to form a sandwich panel having a quadratic and three-dimensional curved surface. (For example, see Patent Documents 1 and 2)

JP-A-5-237955 JP-A-10-329250

The present invention has been made to solve the above-mentioned conventional problems in the case of forming a curved sandwich panel, and its purpose is to cause harmful deformation such as buckling and wrinkling of the front and back plates of the sandwich panel. It is an object of the present invention to provide a multi-curved curved sandwich panel that can be molded with a multi-curved curved surface.

In order to achieve the above object, a curved sandwich panel according to the present invention, as shown in FIGS. 1 to 3, has a core material A having a hollow structure with a honeycomb shape or a polyhedron shape in a three-dimensional CAD or the like in advance. Using the data designed in this shape, before joining with the faceplates 1 and 2, the core material itself is manufactured by the additive manufacturing method represented by the stereolithography method and the powder modeling method so that the core material itself becomes a predetermined three-dimensional shape. Thus, it is a structural feature that it is formed into a complex curved surface shape.

When the honeycomb shape is formed inside the core material A, the cell wall interval 4 in the portion in contact with the back plate 2 having a small radius of curvature is reduced, and the cell wall interval 3 in contact with the surface plate 1 is increased. The second feature of the configuration is to form a natural solid curved surface by controlling the angle.

Furthermore, by forming the hollow core material B by the additive manufacturing method, the outer surface plate 7 can be integrally formed with the same material as the inner cell wall in advance as shown in FIG. 7 is used as a bonding surface with the front and back plates 5 and 6 of higher strength, and the third feature is that the strength of the product is improved and the product strength is improved.

As described above, the multi-curved sandwich panel according to the present invention exhibits the following effects by using the layered manufacturing method for manufacturing the hollow core material.

First, the outer surface shape and the internal structure of the hollow core material can be independently molded before being joined to the face plate. That is, the hollow core material used for the composite curved sandwich panel of the present invention uses a layered modeling method represented by an optical modeling method or a powder modeling method. In this layered modeling method, a predetermined shape is obtained in advance by three-dimensional CAD. The core material shape including the internal structure can be formed according to the data designed in the above, so the core material formed by this additive manufacturing method is far more than the flat honeycomb core material used in the conventional example described above. Excellent molding freedom.

Therefore, the complex curved surface sandwich panel of the present invention employing the hollow core material formed by the additive fabrication method such as the stereolithography method or the powder modeling method is a complex curved surface which the conventional example described above is impossible. Can be formed. That is, since the hollow core material itself has strength and has a predetermined three-dimensional shape independently, it prevents the deformation of the core material caused by the pressure when joining the front and back face plates, and is harmful to the surface. Wrinkles and buckling can be prevented. As a result, if this multi-curved sandwich panel is used, for example, as the structural performance of the leading edge part of recent aircraft wings in which the shape becomes complicated and the strict curvature radius is adopted as performance increases, the rocket As a tip of a flying object such as a wind turbine blade, it can be easily commercialized. That is, it is possible to freely change the plate thickness, and at the same time, it is possible to sufficiently meet the demand for complex shape molding with a strict curvature radius while being highly accurate.

Secondly, it is excellent in processing cost. That is, the complex curved sandwich panel of the present invention has excellent moldability as described above. Therefore, even a relatively thick plate can be formed into a predetermined curvature as it is. Like the core material of the conventional sandwich panel described above, a step of preparing a plurality of core materials whose thicknesses and curvatures are adjusted in advance, respectively forming them into predetermined curvatures, and stacking them in a concentric manner becomes unnecessary. That is, for example, when a curved panel having a severe leading edge radius of curvature of about R = 20 mm, such as a recent aircraft main wing leading edge, is manufactured, the compound curved sandwich panel according to the present invention corresponds to the leading edge shape. Because a core material having a cross-sectional shape having an outer radius and a thickness required to reach a predetermined strength can be molded separately in advance by the additive manufacturing method, and this can be used as it is as a core material for sandwich panels. In addition, a molding die is not required. Thus, this compound curved-surface sandwich panel is excellent in processing cost, such as the processing cost being significantly reduced.

Third, it is excellent in lightness. That is, the complex curved sandwich panel of the present invention has an excellent internal structure design freedom in order to form the core material by the layered manufacturing method. Therefore, where high strength is required, the cell opening cross-section that forms the hollow structure inside the core is reduced to increase the density, and in other areas, the cell opening cross-section is increased to reduce the density. In addition, by individually adjusting the plate thickness of the cell wall, it is possible to prevent an unnecessary increase in weight that could not be avoided with the conventional core material having a uniform plate thickness. By using the multi-curved sandwich panel in this way, the weight of the member is greatly reduced, and the weight is excellent.

Fourth, it is excellent in adaptability. In other words, the existing sandwich panel is manufactured by separately forming the core material in advance by a layered molding method in accordance with the existing mold mold already used for sandwich panel manufacturing, and re-producing the sandwich panel using this core material. However, it is lightweight and high-strength, and can be further reduced in cost. It is excellent in adaptability to sandwich panel manufacturing using existing manufacturing equipment.

Fifth, it can be manufactured easily and easily. That is, the complex curved sandwich panel of the present invention can be easily and easily manufactured by the additive manufacturing method. In other words, if the core shape data designed by 3D CAD is input to the additive manufacturing apparatus, the core material can be formed into a complex curved surface shape. Therefore, if this core is used instead of a mold, a sandwich panel is manufactured easily and easily. In addition, it is possible to manufacture a lightweight curved curved sandwich panel that is excellent in manufacturing cost. Thus, the effect which this invention exhibits is remarkable, such as the problem which existed in the prior art example being solved largely.

The perspective view which notched a partly curved surface sandwich panel in this invention. FIG. 2 is a partial cross-sectional view of FIG. 1. The partial cross section figure at the time of carrying out integral molding of the thin joining surface 7 for strengthening joining with front and back plates on the outer surface of the hollow core material A of FIG. The perspective view which notched a part of structure of the double curved surface sandwich panel applied to the wing leading edge of the aircraft manufactured by the conventional construction method. FIG. 5 is a partial cross-sectional view of FIG. 4. The perspective view which shows the structure of the plane sandwich panel manufactured by the conventional general construction method. Sectional drawing of the component manufacture process by the optical modeling method which is a representative example of the additive manufacturing method.

Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

(First Example)
1 to 2 show a first embodiment of the present invention. FIG. 1 is a perspective view of a complex curved sandwich panel, FIG. 2 is a partial cross-sectional view of FIG. 1, and FIG. 7 is a cross-sectional view of an optical modeling method that is a representative example of the additive manufacturing method.
First, in FIG. 1, the manufacturing method of the hollow core material A shape | molded by layered modeling methods, such as this optical modeling method and a powder modeling method, is demonstrated. Although a quadric curved sandwich panel will be described as an example of a complex curved sandwich panel, a cubic curved sandwich panel whose cross-sectional shape changes in the span direction can also be used. Here, the stereolithography will be described as a representative example.

As shown to Fig.7 (a), the raising / lowering stand Q driven outside a figure is set so that raising / lowering is possible in the tank P filled with photocurable resin. When the upper surface of the elevator table Q is set at a position lower by 1 pitch (for example, 0.15 mm) than the surface of the photocurable resin, a photocurable resin layer for one pitch is formed on the upper surface of the elevator table Q. In this state, the photocurable resin thin film on the lifting platform Q is irradiated with a predetermined pattern of ultraviolet laser R, and the photocurable resin corresponding to the irradiated portion is cured to form the first resin layer. Subsequently, as shown in FIG. 7 (b), after the elevator platform Q is lowered by one pitch, the photocurable resin thin film covering the upper surface of the first resin layer is irradiated with an ultraviolet laser R having a predetermined pattern, The photocurable resin corresponding to the irradiated portion is cured to mold the second resin layer laminated on the first resin layer. In this way, the entire hollow core material A is sequentially formed from one end side to the other end side in the span direction by irradiating the ultraviolet laser R every time the lifting platform Q is lowered by one pitch (FIG. 7 (c)). See also)

In this way, by adopting the layered manufacturing method typified by the optical modeling method, the hollow core material A having a complicated internal shape can be integrally formed with high accuracy and at low cost.

As shown in FIGS. 1A, the hollow core material A used for manufacturing a sandwich panel having a multi-curved surface in the present invention is a predetermined composite material itself independently by a three-dimensional CAD or the like. Designed to be a curved surface, it is integrally formed with the internal hollow polyhedron structure by the layered modeling method typified by the above-mentioned stereolithography method, and fiber reinforced plastic or aluminum having a shape along the outer shape of the hollow core material A on the front and back By joining the face plates 1 and 2 such as plates, a high-strength double curved surface sandwich panel is configured.

(Second embodiment)
In the first embodiment of the present invention as described above, the portions 3 and 4 where the hollow core material A is in contact with the front and back plates 1 and 2 are end surfaces of the cell walls constituting the hollow core material A. When the hollow core material A and the front and back plates 1 and 2 are bonded to each other, the bonded portion becomes extremely thin and a sufficient bonding area may not be obtained. Therefore, in the second embodiment, in order to increase the bonding area and strengthen the bonding, when forming the hollow core material B as shown in FIG. After integrally molding with the raw material, and then bonding the front plate 5 and the back plate 6 to the face plate 7 formed integrally with the hollow core material B, the hollow core material B and the front and back face plates 5, 6 Is firmly bonded.

Thus, if the thin face plate 7 is integrally formed on the outer periphery of the hollow core material B, the uncured resin remains inside the hollow core material B. Therefore, a small hole H (about 2 mm in diameter) for removing the resin can be set in the integrally formed thin face plate 7. As shown in FIG. 3, the resin-excluded small hole H can be set by penetrating the hollow core material B on the side surface in the span direction end of the hollow core material B. By providing two or more small holes H in one cell, residual resin can be effectively removed. Of course, the small hole H may be in an open state, but may be filled with a homogeneous resin.

(Third embodiment)
By the way, since the hollow core materials A and B are independently formed into a three-dimensional shape by a layered manufacturing method typified by an optical modeling method, the internal hollow structure can be freely configured. That is, the honeycomb shape is typical, but depending on the structural characteristics required at the time of completion, it can be formed by space filling with a polyhedron such as a substantially tetrahedron or a truncated octahedron, and is derived from the requirements of strength and weight. It can be constituted by a combination of arbitrary internal shapes.

(Fourth embodiment)
Further, in FIG. 2, since the thickness and shape of the plate wall of the cell constituting the inside of the hollow core material A can be freely designed, the hollow core is formed near the portion where the front and back plates 1 and 2 are joined. The part where the thickness of the material A is thin is solidly shaped to increase the strength, prevent harmful wrinkles and buckling when joining the front and back plates 1 and 2, and the strength required for the double curved sandwich panel Various adjustments can be performed such as partially strengthening the cell plate wall to meet the requirements.

(5th Example)
Then, it is also possible to preliminarily form holes and notches into the hollow core materials A and B for inserting a reinforcing member into the inside of the thus-formed complex curved sandwich panel.

(Sixth embodiment)
By the way, the face plates 1, 2, 5 and 6 to be joined to the front and back of the hollow core materials A and B are independent of the hollow core materials A and B. It is also possible to mold products by laminating plastics. However, when the heat resistance of the hollow core materials A and B cannot withstand the firing temperature of the fiber reinforced plastic used for forming the face plate, or when the process becomes inefficient, it is bonded to the metal face plate. In the case of doing so, the face plates 1, 2, 5 and 6 may be formed and fired in advance by using a separately prepared molding mold having the same shape as the hollow core materials A and B, and then bonded by bonding. it can.

(Seventh embodiment)
Furthermore, if a metal material is used for forming the hollow core material used in the present invention, it becomes possible to form a hollow core material made of metal. By joining the metal front and back plates to this metal hollow core material, it is extremely A complex curved sandwich panel with high strength and specific rigidity can be manufactured. Thus, the hollow core material and the material of the front and back plates can be selected in any combination.

The present invention relates to a double curved honeycomb panel and a manufacturing method thereof. That is, it has a quadratic curved surface, a cubic curved surface, a curved surface in which these curved surfaces are continuously integrated, and other complex curved surfaces, and various devices such as an aircraft wing leading edge, a rocket tip outer wall, a wind turbine blade, The present invention relates to a complex curved sandwich panel used for a structural member and a method for producing the same.

A A hollow core material B A hollow core material formed integrally with a thin plate on the surface C A moderately curved honeycomb core material D by a conventional method D A sandwich panel using a general planar honeycomb core H A small hole for removing residual resin 1 Surface plate 2 Back Face plate 3 Front side large open cell 4 Back side small open cell 5 Front plate 6 Back plate 7 Thin plate 8 integrally molded with hollow core material Front plate 9 Back plate 10 Front plate 11 Back plate

Claims (4)

In a complex curved sandwich panel formed by joining face plates to the front and back surfaces of the core material A having a large number of hollow polyhedral structures inside,
Before the hollow core material is joined to the face plates 1 and 2, the core material itself is a secondary or tertiary curved surface that is integrally formed by a layered manufacturing method so that the core material itself independently becomes a predetermined three-dimensional shape. A multi-curved sandwich panel comprising an outer shape and cell walls constituting a large number of hollow polyhedrons, wherein a face plate is joined to the front and back surfaces of the core material. The hollow core material A is provided with a honeycomb structure, and the cell walls 3 constituting the honeycomb structure are integrally molded by controlling the angle of adjacent cell walls in a direction substantially orthogonal to the front and back plates 1 and 2. The double curved surface sandwich panel according to claim 1, wherein: 2. The hollow core material A is provided with a space filling structure composed of cells constituting one or several types of polyhedrons, and the cell space is a three-dimensional aggregate. Double curved curved sandwich panel as described. The double curved surface sandwich panel according to claim 1, wherein a thin face plate (7) made of the same material as the cell wall is integrally formed with the cell wall on the front and back surfaces of the hollow core material.