Hollow structure and method for manufacturing a hollow structure

Abstract

A hollow structure body (10) is provided with: a hollow plate material (11) made of thermoplastic resin in which a plurality of cells are juxtaposed; and an attachment member (30) that is configured to be attached and fixed to an inner wall (4) of a jet engine of an aircraft. The hollow plate material (11) is provided with: a core layer (20) having a plurality of side wall parts that partition the plurality of cells; a first skin layer (24) that is laminated on a first main surface of the core layer (20); and a second skin layer (25) that is laminated on a second main surface of the core layer (20). The attachment member (30) is provided with a columnar body part (31) extending in the thickness direction of the hollow plate material (11). The side surface of the body part (31) is welded to the side wall parts of the core layer (20). The body part (31) is not exposed from the outer surface of the first skin layer (24).

Description

Technical Field

[0001] The present disclosure relates to a hollow structure and a method for manufacturing the hollow structure.

Background Art

[0002] From the viewpoints of weight reduction, fuel efficiency improvement, etc., structures made of resin materials are known as structures for use in aircraft, automobiles, etc. There are cases where a structure made of a resin material is attached to an attachment target by an attachment member, or a structure in which a plurality of structures made of a resin material are joined to each other by a joining member is attached to an attachment target.

[0003] Patent Document 1 describes a method of joining two thin plate-like structures by a joining member. At least one of the two structures is formed of a fiber reinforced plastic. Further, the joining member has a frustum-shaped shaft and a head formed at one end of the shaft and having a larger diameter than the shaft. In a state where the two structures are overlapped, the shaft-side end portion of the joining member is pressed against the surface of one structure and rotated, so that the resin in the fiber reinforced resin is thermally melted and joined to the joining member. Thereby, the two structures are assembled by the joining member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The joining member described in Patent Document 1 has a shaft that is longer than the combined thickness of the two structures. Therefore, in the two joined structures, the head of the joining member protrudes from one surface, and the end of the shaft of the joining member protrudes from the other surface. Consequently, if a structure joined with such a joining member is attached to the inner wall of a jet engine at the portion of the joining member, there is a concern that the protruding portion of the joining member may disturb the airflow within the air passage of the jet engine. [Means for solving the problem]

[0006] A hollow structure according to one aspect of the present disclosure is a hollow structure configured to be attached to and fixed to the inner wall of a jet engine of an aircraft to be attached, comprising: a hollow plate material made of thermoplastic resin having a plurality of cells arranged in parallel inside; and a mounting member configured to be attached to and fixed to the inner wall, wherein the hollow plate material comprises a core layer having a plurality of side wall portions extending in the thickness direction of the hollow plate material and partitioning the plurality of cells; a first skin layer laminated on a first main surface of the core layer; and a second skin layer laminated on a second main surface of the core layer, wherein the mounting member comprises a columnar main body portion extending in the thickness direction of the hollow plate material, the side surface of the main body portion is welded to the side wall portion of the core layer, and the main body portion is not exposed from the outer surface of the first skin layer.

[0007] According to the above configuration, since the mounting member is not exposed on the first skin layer side of the hollow plate material, no irregularities are formed on the surface of the hollow structure on the first skin layer side due to the mounting member. Therefore, the surface of the hollow plate material on the first skin layer side can be made flat. Furthermore, by attaching the hollow structure to the inner wall of the jet engine so that the first skin layer faces the air passage side of the jet engine, turbulence in the airflow within the jet engine can be suppressed. In addition, since the main body of the mounting member is welded to the side wall of the core layer, it is firmly fixed to the hollow plate material. When the hollow structure is attached to the inner wall of the jet engine with the mounting member, the attachment state is stable.

[0008] In the above configuration, it is preferable that the main body portion has an edge that is welded to the inner surface of the first skin layer. According to the above configuration, the main body of the mounting member is welded not only to the side wall of the core layer but also to the first skin layer. Therefore, the mounting member is more firmly fixed.

[0009] In the above configuration, it is preferable that the main body portion has an end portion with a flange portion that protrudes radially, and that the flange portion is welded to the second skin layer. With the above configuration, not only the main body of the mounting member but also the flange portion of the mounting member is welded to the second skin layer, thus providing a more secure fixation of the mounting member.

[0010] In the above configuration, it is preferable that the main body portion has a mounting hole that extends in the axial direction. According to the above configuration, for example, if screws are used as fixing members for attaching and securing to the inner wall of an aircraft's jet engine, the screws can be easily inserted into the mounting holes. The hollow structure can be easily attached to the inner wall of the jet engine.

[0011] A method for manufacturing a hollow structure according to one aspect of the present disclosure comprises a hollow plate made of thermoplastic resin having a plurality of cells arranged in parallel inside, and a columnar mounting member configured to be attached and fixed to the inner wall of a jet engine, comprising a welding step in which the mounting member is moved from a first main surface to a second main surface of the hollow plate while the hollow plate and the mounting member are rotated relative to each other, thereby welding the mounting member to the inside of the hollow plate by frictional heat generated between the hollow plate and the mounting member, wherein in the welding step, the mounting member is moved within a range in which the mounting member is not exposed from the second main surface.

[0012] According to the above configuration, in the welding process, the frictional heat generated by the relative rotation between the hollow plate material and the mounting member melts the thermoplastic resin hollow plate material, welding the mounting member to the inside of the hollow plate material. As a result, a hollow structure is obtained in which the mounting member is firmly fixed to the hollow plate material. This allows for stable mounting to the inner wall of the jet engine. Furthermore, in the welding process, the mounting member is moved to a position where it is not exposed from the second main surface of the hollow plate material and then heat-welded. As a result, a hollow structure with a flat second main surface is obtained. If the hollow structure is mounted so that the second main surface side faces the air passage side of the jet engine, turbulence in the airflow within the jet engine can be suppressed. [Effects of the Invention]

[0013] According to this disclosure, a hollow structure can be obtained that can suppress airflow turbulence when attached to the inner wall of a jet engine. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram illustrating the structure of an aircraft jet engine. [Figure 2] This is a cross-sectional view of a hollow structure attached to the nacelle, which forms the inner wall of a jet engine. [Figure 3] This is a partial perspective view of a hollow structure. [Figure 4] This is a partial perspective view of the mounting component. [Figure 5] This is a cross-sectional view of the mounting component. [Figure 6] This is a perspective view of a hollow sheet material. [Figure 7] Figure 6 is a cross-sectional view taken using β-β rays. [Figure 8] Figure 6 is a cross-sectional view using gamma rays. [Figure 9] This is a diagram illustrating the manufacturing method of hollow sheet material. [Figure 10] This is a diagram illustrating a method for manufacturing a hollow structure. [Figure 11] This diagram illustrates the welding state of the mounting components. [Figure 12] It is a cross-sectional view of a hollow structure of a modified example. [Figure 13] It is a cross-sectional view of a mounting member of a modified example. [Figure 14] It is a cross-sectional view of a hollow structure of a modified example. [Figure 15] It is a cross-sectional view of a hollow structure of a modified example. [Figure 16] It is a cross-sectional view of a hollow structure of a modified example. [Figure 17] It is a cross-sectional view of a hollow structure of a modified example. [Figure 18] It is a cross-sectional view of a mounting member of a modified example.

Mode for Carrying Out the Invention

[0015] Hereinafter, a hollow structure 10 of an embodiment embodying the present invention will be described. As shown in FIG. 1, an aircraft jet engine 1 utilizes air as a working fluid and obtains thrust by sucking in air from the front and ejecting it rearward. The jet engine 1 has a fan 3 disposed in front of an engine 2 having a compression chamber, a combustion chamber, and a turbine. The engine 2 is housed in a nacelle 4. The air taken in from the front of the jet engine 1 is compressed by the fan 3. A part of the compressed air is ejected rearward through an air flow path via a structural guide vane 5 between the nacelle 4 and the engine 2 and is used as thrust for the aircraft. On the other hand, the remaining air is taken into the engine 2, compressed in the compression chamber, burned in the combustion chamber, and drives a turbine that is a driving source for the fan 3.

[0016] In such a jet engine 1, sound-absorbing panels are installed facing the air passage to absorb noise generated in the air passage and noise generated by aerodynamic interference between the fan 3 and the structural guide vane 5. In Figure 1, for example, a hollow structure 10 is installed on the nacelle 4, which forms the inner wall of the housing of the jet engine 1, as a sound-absorbing panel with excellent sound absorption performance. In Figure 1, the jet engine 1 is shown in a cross-sectional view, allowing the internal air passage to be seen, so that the installation position of the hollow structure 10 is easy to understand.

[0017] As shown in Figure 2, the hollow structure 10 is attached and fixed to the nacelle 4, which is the inner wall of the jet engine 1 to which it is to be attached, by a fixing member 50. The hollow structure 10 is attached to the nacelle 4 such that one main surface 10a faces the air passage of the jet engine 1 and the other main surface 10b faces the inner surface of the nacelle 4.

[0018] As shown in Figures 2 and 3, the hollow structure 10 comprises a hollow plate material 11 and mounting members 30. The hollow plate material 11 and the mounting members 30 are made of a known thermoplastic resin material. The mounting members 30 are fixed to the inside of the hollow plate material 11 by heat welding. Multiple mounting members 30 are fixed to the hollow plate material 11 at intervals.

[0019] As shown in Figure 2, the fixing member 50 of this embodiment includes a countersunk screw 51 and a nut 52 that is screwed onto the tip of the countersunk screw 51. Multiple mounting seats 41 for attaching and fixing the hollow structure 10 are formed on the inner circumferential surface of the nacelle 4. A recess 42 is formed in each mounting seat 41. The hollow structure 10 is attached to the nacelle 4 by screwing the countersunk screw 51, which is attached via the mounting member 30, into the nut 52 that is fitted into the recess 42.

[0020] First, the hollow plate material 11 and the mounting member 30 that constitute the hollow structure 10 will be described. <About Hollow Plate Material 11> The structure of the hollow plate material 11 and its manufacturing method will be explained with reference to Figures 6 to 9. For convenience, in the following explanation, the vertical direction of the hollow plate material 11 will be defined according to the vertical directions shown in Figures 6 to 8.

[0021] As shown in Figure 6, the hollow plate material 11 comprises a core layer 20 in which a plurality of cells S are arranged side by side inside, and a sheet-like first skin layer 24 and a second skin layer 25 joined to both sides of the core layer 20 in the thickness direction. The core layer 20 is formed by folding a first sheet material 100, which is a single sheet material made of thermoplastic resin molded into a predetermined shape. The core layer 20 includes an upper wall portion 21, a lower wall portion 22, and a side wall portion 23 erected between the upper wall portion 21 and the lower wall portion 22 to partition the cells S into a hexagonal prism shape.

[0022] As shown in Figures 7 and 8, the cells S partitioned within the core layer 20 include a first cell S1 and a second cell S2 with different configurations. As shown in Figure 7, in the first cell S1, a two-layer upper wall 21 is provided above the side wall 23. Each layer of this two-layer upper wall 21 is joined to the others. Also in the first cell S1, a single-layer lower wall 22 is provided below the side wall 23. On the other hand, as shown in Figure 8, in the second cell S2, a single-layer upper wall 21 is provided above the side wall 23. Also in the second cell S2, a two-layer lower wall 22 is provided below the side wall 23. Each layer of this two-layer lower wall 22 is joined to the others. Furthermore, as shown in Figures 7 and 8, adjacent first cells S1 and adjacent second cells S2 are partitioned between each other by two-layer side wall 23s.

[0023] As shown in Figure 6, the first cells S1 are arranged in a row along the X direction, and when viewed from above, two adjacent first cells S1 share one side of a hexagon. Similarly, the second cells S2 are arranged in a row along the X direction, and when viewed from above, two adjacent second cells S2 share one side of a hexagon. The rows of first cells S1 and second cells S2 are arranged alternately in the Y direction, which is perpendicular to the X direction. These first cells S1 and second cells S2 form a honeycomb structure as a whole in the core layer 20. Note that in Figure 6, the configuration of the two-layer structure of the upper wall 21 and lower wall 22 is omitted.

[0024] As shown in Figures 6 to 8, a first skin layer 24, which is a sheet material made of thermoplastic resin, is bonded to the upper surface, which is the first main surface of the core layer 20. In addition, a second skin layer 25, which is a sheet material made of thermoplastic resin, is bonded to the lower surface, which is the second main surface of the core layer 20. In this embodiment, the upper part of the side wall portion 23 of the core layer 20 is closed by the upper wall portion 21 and the first skin layer 24 of the core layer 20. Similarly, the lower part of the side wall portion 23 of the core layer 20 is closed by the lower wall portion 22 and the second skin layer 25 of the core layer 20.

[0025] As shown in Figures 6 to 8, the hollow plate material 11 has a main surface 11a which is the surface of the first skin layer 24, and a communication hole 12 that connects the inside and outside of the cell S is opened in the main surface 11a. Specifically, as shown in Figure 7, in the first cell S1, the communication hole 12 penetrates the first skin layer 24 and the upper wall portion 21 of the two-layer structure. Also, as shown in Figure 8, in the second cell S2, the communication hole 12 penetrates the first skin layer 24 and the upper wall portion 21 of the single-layer structure.

[0026] As shown in Figure 6, one communication hole 12 is provided for each cell S. In this embodiment, when the hollow plate material 11 is viewed from above, the communication hole 12 is located in the center of the hexagonal shape of each cell S. As shown in Figures 7 and 8, the diameter of the opening of each communication hole 12 is set to be less than or equal to the length of one side of the hexagon when the cell S is viewed from above. Specifically, the diameter of the opening of each communication hole 12 is set to a fraction of the distance P1 between the centers of adjacent cells S in the X direction (for example, about 0.5 to 3.0 mm). Also, the opening edge 12a of the communication hole 12 is located in the internal space of the cell S.

[0027] The thermoplastic resin material used for the core layer 20, the first skin layer 24, and the second skin layer 25 can be appropriately selected from known materials. From the viewpoint of excellent scratch resistance (abrasion resistance), impact resistance, heat resistance, cold resistance, oil resistance, chemical resistance, and mechanical strength, polyamide resins, and among them nylon resins, are preferred. Examples of nylon resins include nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 6T, nylon 6I, nylon 9T, nylon M5T, nylon 612, etc., but among these nylon resins, nylon 6 is more preferred because it has appropriate elasticity (flexibility) and therefore excellent scratch resistance and impact resistance.

[0028] Furthermore, the thermoplastic resin material may also be a polyamide-based elastomer resin, which is obtained by compounding an elastomer with these polyamide resins. Because polyamide-based elastomer resins have excellent elasticity (flexibility), impact resistance can be further improved.

[0029] Alternatively, among the layers constituting the hollow plate material 11, a polyamide elastomer resin may be used only for the first skin layer 24, which is positioned to face the inside of the air passage, while a polyamide resin without elastomer may be used for the core layer 20 and the second skin layer 25. This is preferable because it allows for the appropriate maintenance of the strength of the hollow structure 10 while ensuring impact resistance on the air passage side.

[0030] From the viewpoint of ease of processing of the hollow plate material 11, among nylon resins, those with a water absorption rate of 0.5% to 1.0% are preferred, those with a water absorption rate of 0.5% to 0.7% are more preferred, and those with a water absorption rate of 0.5% to 0.6% are even more preferred. By keeping the water absorption rate within this range, foaming due to the absorption of moisture from the air by the nylon resin is suppressed during the molding process of the hollow structure 10, during storage, or when the hollow structure 10 is bent or otherwise processed.

[0031] Next, the manufacturing method for the hollow plate material 11 will be explained with reference to Figure 9. As shown in Figure 9, the hollow plate material 11 is formed by folding the first sheet material 100. The first sheet material 100 is formed by molding a single sheet of thermoplastic resin into a predetermined shape. The first sheet material 100 has strip-shaped planar regions 110 and bulging regions 120 arranged alternately in the longitudinal direction (X direction) of the first sheet material 100. In the bulging region 120, a first bulge portion 121, which has a downward groove-like cross-section consisting of an upper surface and a pair of side surfaces, is formed over the entire length of the bulging region 120 in the direction in which it extends (Y direction). Preferably, the angle between the upper surface and the side surface of the first bulge portion 121 is 90 degrees, and as a result, the cross-sectional shape of the first bulge portion 121 is a downward channel shape. Furthermore, the width of the first bulge 121 (length in the shorter direction of the upper surface) is set to be equal to the width of the planar area 110, and to be twice the bulge height of the first bulge 121 (length in the shorter direction of the side surface).

[0032] Furthermore, the bulging region 120 has multiple second bulges 122, each having a trapezoidal cross-section obtained by bisecting a regular hexagon with its longest diagonal, formed perpendicular to the first bulge 121. The bulge height of the second bulges 122 is set to be equal to the bulge height of the first bulge 121. The spacing between adjacent second bulges 122 is equal to the width of the upper surface of the second bulge 122.

[0033] The first bulge 121 and the second bulge 122 are formed by utilizing the plasticity of the sheet to partially bulge the sheet upward. Furthermore, the first sheet material 100 can be formed from a single sheet using well-known molding methods such as vacuum forming or compression molding.

[0034] The core layer 20 is formed by folding the first sheet material 100, configured as described above, along boundary lines P and Q. Specifically, the first sheet material 100 is valley-folded at boundary line P between the planar region 110 and the bulging region 120, and mountain-folded at boundary line Q between the upper surface and side surface of the first bulging portion 121, thereby compressing it in the X direction. As the upper surface and side surface of the first bulging portion 121 overlap, and the end surface of the second bulging portion 122 overlaps with the planar region 110, a prismatic partition 130 extending in the Y direction is formed for each bulging region 120. A hollow plate-like core layer 20 is formed by continuously forming such partitions 130 in the X direction. In this embodiment, the direction in which the first sheet material 100 is compressed for folding is the direction in which the cells S are arranged side by side (X direction).

[0035] When the first sheet material 100 is compressed as described above, the upper wall portion 21 of the core layer 20 is formed by the upper surface and side surface of the first bulge portion 121, and the lower wall portion 22 of the core layer 20 is formed by the end surface of the second bulge portion 122 and the planar region 110. The portion of the upper wall portion 21 in which the upper surface and side surface of the first bulge portion 121 overlap to form a two-layer structure, and the portion of the lower wall portion 22 in which the end surface of the second bulge portion 122 and the planar region 110 overlap to form a two-layer structure, are each called overlapping portions 131.

[0036] Furthermore, the hexagonal prism-shaped region formed by the folding of the second bulge 122 becomes the second cell S2, and the hexagonal prism-shaped region formed between a pair of adjacent partitions 130 becomes the first cell S1. In this embodiment, the upper surface and side surface of the second bulge 122 constitute the side wall portion 23 of the second cell S2, and the side surface of the second bulge 122 and the planar portion located between the second bulges 122 in the bulging region 120 constitute the side wall portion 23 of the first cell S1. The contact portions of the upper surfaces of the second bulges 122 and the contact portions of the planar portions in the bulging region 120 form a two-layer side wall portion 23. In addition, the upper part of the first cell S1 is partitioned by a pair of overlapping portions 131, and the lower part of the second cell S2 is partitioned by a pair of overlapping portions 131. Furthermore, when carrying out this folding process, it is preferable to heat-treat the first sheet material 100 to soften it.

[0037] A second sheet material made of thermoplastic resin is joined to the upper and lower surfaces of the core layer 20 obtained in this manner by heat welding. The second sheet material joined to the upper surface of the core layer 20 becomes the first skin layer 24, and together with the upper wall portion 21 of the core layer 20, closes the cell S from above. The second sheet material joined to the lower surface of the core layer 20 becomes the second skin layer 25, and together with the lower wall portion 22 of the core layer 20, closes the cell S from below.

[0038] When the second sheet material (first skin layer 24 and second skin layer 25) is heat-welded to the core layer 20, the upper wall portion 21 (overlapping portion 131) of the two-layer structure in the first cell S1 is heat-welded to each other. Similarly, the lower wall portion 22 (overlapping portion 131) of the two-layer structure in the second cell S2 is heat-welded to each other.

[0039] Through the above steps, a hollow plate material 11 is obtained in which a large number of first cells S1 or second cells S2 are arranged in rows in the X direction, and a large number of first cells S1 and second cells S2 are arranged alternately in the Y direction.

[0040] Subsequently, numerous communication holes 12 are formed in the first skin layer 24 and the upper wall portion 21 of the core layer 20 of the hollow plate material 11. The communication holes 12 are formed by penetrating the hollow plate material 11 through the main surface 11a with a penetrating jig T such as a drill, needle, or punch. Multiple penetrating jigs T are arranged at approximately the same intervals as the distances between the centers of adjacent cells S. The hollow plate material 11 is positioned and fixed below the multiple penetrating jigs T, and the penetrating jigs T are moved downward. In this way, one communication hole 12 is formed in the main surface 11a of the hollow plate material 11, approximately in the center of each cell S. Through the above process, a hollow plate material 11 with multiple communication holes 12 is manufactured.

[0041] <Regarding mounting component 30> As shown in Figures 4 and 5, the mounting member 30 has a generally cylindrical shape. For convenience, in the following description, the tip and base of the mounting member 30 will be defined as shown in Figure 4. Also, the mounting member 30 described here is in its shape before being attached to the hollow plate material 11 and used as a hollow structure 10.

[0042] As shown in Figures 4 and 5, the mounting member 30 has a frustoconical body portion 31 formed at its tip, with the diameter becoming slightly smaller towards the tip. The ratio (L1 / L2) of the diameter L1 at the base edge of the body portion 31 to the diameter L2 at the tip surface 31a of the body portion 31 is preferably greater than 1 and less than or equal to 2, more preferably about 1.1 to 1.5, and even more preferably about 1.1 to 1.3. When L1 / L2 is within this range, the spin welding process, which will be described later, is easier to perform. In addition, the positioning accuracy of the mounting member 30 is improved, strong welding with the side wall portion 23 of the core layer 20 can be achieved, and the strength of the hollow structure 10 can be ensured.

[0043] The angle between the tip surface 31a of the main body portion 31 and the outer peripheral surface of the main body portion 31 is preferably greater than 90° and 135° or less, more preferably greater than 90° and 110° or less, and even more preferably greater than 90° and 100° or less.

[0044] A flange portion 33 is formed at the base end of the main body portion 31, extending radially from the main body portion 31. As shown in Figure 5, the tip side surface of the flange portion 33 is formed as an inclined surface 33b, which gradually decreases in diameter towards the tip. The angle between the base end surface 33a and the inclined surface 33b of the flange portion 33 is preferably about 15 to 75°, more preferably about 25 to 65°, and even more preferably about 35 to 55°. When the angle between the base end surface 33a and the inclined surface 33b is within this range, the flange portion 33 can easily enter the interior of the hollow plate material 11 during the spin welding process, making the spin welding work easier. In addition, the positioning accuracy of the mounting member 30 is improved, strong welding with the side wall portion 23 of the core layer 20 can be achieved, and the strength of the hollow structure 10 can be ensured.

[0045] The thickness of the flange portion 33 is preferably about 0.5 to 5 times the thickness of the second skin layer 25. When the thickness of the flange portion 33 is within this range, the welding strength of the mounting member 30 is improved, and a strong weld with the side wall portion 23 can be achieved. In this embodiment, the thickness of the flange portion 33 is greater than the thickness of the second skin layer 25, as shown in Figure 2.

[0046] As shown in Figure 5, a circular cross-section recess 32 extending in the axial direction is provided in the center of the main body portion 31. The recess 32 opens onto the front end surface 31a of the main body portion 31. The recess 32 extends to the front edge of the flange portion 33.

[0047] As shown in Figures 4 and 5, four locking holes 35 are formed in the base end face 33a of the flange portion 33. The locking holes 35 are for locking and fixing the holder during spin welding, which will be explained later. In addition, the locking holes 35 are material-reducing parts, so weight can be reduced while preventing a decrease in strength. A head 34 is formed on the base end side of the mounting member 30. The head 34 is formed in a cylindrical shape with a smaller diameter than the main body portion 31.

[0048] As shown in Figures 5, 7, and 8, the diameter L3 at the center H1 in the height direction of the mounting member 30 is preferably about 1.0 to 1.5 times the distance M1 between a pair of opposing side walls 23 in the cell S of the core layer 20, and more preferably about 1.1 to 1.3 times. When the diameter L3 is within this range, the necessary strength can be achieved when the hollow structure 10 is attached to the nacelle 4.

[0049] <About the hollow structure 10> As shown in Figure 3, the hollow structure 10 comprises a hollow plate material 11 and a mounting member 30 fixed to the inside of the hollow plate material 11 by heat welding. The mounting member 30 is fixed so that the thickness direction of the hollow plate material 11 and the axial direction of the main body 31 coincide. A sheet material 13 made of the same thermoplastic resin material as the second sheet material (first skin layer 24 and second skin layer 25) is welded and sealed to the side surface of the hollow plate material 11.

[0050] The mounting member 30 is fixed to the hollow plate material 11 such that the tip surface 31a of the main body portion 31 is located near the main surface 11a of the hollow plate material 11, and the head portion 34 is located near the main surface 11b of the hollow plate material 11. In other words, the mounting member 30 is fixed to the hollow plate material 11 such that the tip surface 31a of the main body portion 31 is located on the side of the hollow plate material 11 where the communication hole 12 is formed.

[0051] As shown in Figures 2 and 3, the side surface of the main body portion 31 of the mounting member 30 is welded to the side wall portion 23 of the core layer 20 that constitutes the hollow plate material 11, so as to follow the side surface of the side wall portion 23. Furthermore, the leading edge of the main body portion 31 is welded to the inner surface of the first skin layer 24 of the hollow plate material 11 in such a manner that it is not exposed from the first skin layer 24 of the hollow plate material 11. As a result, the main surface 10a of the hollow structure 10 is formed as a flat surface. In addition, the flange portion 33 of the mounting member 30 is welded to the second skin layer 25 such that its base end surface 33a is flush with the outer surface of the second skin layer 25. In other words, the base end surface 33a of the flange portion 33 is flush with the main surface 10b of the hollow plate material 11. The head portion 34 of the mounting member 30 protrudes from the second skin layer 25 of the hollow plate material 11. Note that in Figures 2 and 3, the upper wall portion 21, lower wall portion 22, and side wall portion 23 of the core layer 20 of the hollow plate material 11 are omitted.

[0052] As shown in Figure 3, the mounting member 30, which is attached to the hollow plate material 11 and forms part of the hollow structure 10, has a mounting hole 36 with a circular cross-section that extends in the axial direction. The mounting hole 36 opens to the front end surface 31a of the main body portion 31 and the base end surface 34a of the head portion 34. At the end of the mounting hole 36 that opens to the front end surface 31a of the main body portion 31, a housing portion 37 is formed that gradually increases in diameter toward the front end surface 31a.

[0053] As shown in Figure 2, the mounting hole 36 is the portion into which the countersunk screw 51 of the fixing member 50 is inserted. The housing portion 37 is the portion that houses the head 51a of the countersunk screw 51. The mounting hole 36 is formed by a post-processing step during the manufacturing of the hollow structure 10, by passing the recess 32 through in the axial direction.

[0054] In a hollow structure 10 in which a mounting member 30 is welded and fixed to a hollow plate material 11, the main surface 11a of the hollow plate material 11 becomes the main surface 10a of the hollow structure 10, and the main surface 11b of the hollow plate material 11 becomes the main surface 10b of the hollow structure 10.

[0055] <Regarding the manufacturing method of the hollow structure 10> Next, the manufacturing method of the hollow structure 10 will be described with reference to Figure 10. The manufacturing process of the hollow structure 10 includes a spin welding process for attaching the mounting member 30 to the hollow plate material 11, and a post-processing process for forming the mounting hole 36. In Figure 10, the two upper figures illustrate the spin welding process, and the two lower figures illustrate the post-processing process.

[0056] First, prepare hollow plate material 11 cut to a predetermined shape and size. As shown in Figure 10, in the spin welding process, the cut hollow plate material 11 is placed on the base of the spin welding machine with its main surface 11a facing downwards. A holder (not shown) of the spin welding machine is locked into the locking hole 35 of the mounting member 30, and the mounting member 30 is positioned to face the main surface 11b of the hollow plate material 11. In this embodiment, the main surface 11b is the first main surface, and the main surface 11a is the second main surface.

[0057] Next, the mounting member 30, which is locked to the spin welding machine, is moved downward so that the tip of the main body portion 31 of the mounting member 30 comes into contact with the main surface 11b of the hollow plate material 11. In this state, as the mounting member 30 is moved downward while rotating at high speed, frictional heat is generated between the hollow plate material 11 and the mounting member 30, causing the hollow plate material 11 around the mounting member 30 to melt. The main body portion 31 of the mounting member 30 is inserted into the hollow plate material 11 while melting the hollow plate material 11.

[0058] The molten resin of the hollow plate material 11 adheres to the side surface of the main body portion 31 of the mounting member 30, forming a resin reservoir. The molten resin also enters the recess 32 from the tip surface 31a of the main body portion 31. Furthermore, the molten resin pressed by the tip surface 31a of the main body portion 31 forms a resin reservoir with a curved cross-section that rises up at the tip side of the tip surface 31a.

[0059] The downward movement of the mounting member 30 is performed within a range in which the tip of the mounting member 30 is not exposed from the main surface 11a of the hollow plate material 11. Specifically, the rotation and downward movement of the mounting member 30 are stopped when the tip surface 31a of the main body portion 31 of the mounting member 30 is in contact with the inner surface of the first skin layer 24 of the hollow plate material 11. At this time, the resin reservoir with an arc-shaped cross-section on the tip side of the tip surface 31a remains within the thickness range of the first skin layer 24. The resin reservoir on the tip side of the tip surface 31a is larger than that on the flange portion 33 and the outer surface of the main body portion 31 of the mounting member 30. As a result, the tip of the main body portion 31 of the mounting member 30 has a higher resin density than other parts of the mounting member 30.

[0060] Subsequently, the holder of the spin welding machine is removed, and the hollow plate material 11 to which the mounting member 30 is attached is allowed to cool naturally. As a result, the side surface of the main body portion 31 of the mounting member 30 is welded to the side wall portion 23 of the core layer 20 that constitutes the hollow plate material 11. In addition, the side surface of the main body portion 31 is also welded to the resin reservoir formed when the hollow plate material 11 is thermally melted.

[0061] The leading edge of the main body portion 31 of the mounting member 30 is welded to the inner surface of the first skin layer 24 that constitutes the hollow plate material 11, and the welding is performed in such a manner that the arc-shaped resin reservoir at the leading edge of the main body portion 31 remains within the thickness range of the first skin layer 24. The flange portion 33 of the mounting member 30 is welded to the second skin layer 25 such that its base end surface 33a is flush with the outer surface of the second skin layer 25. Because the resin reservoir at the leading edge of the main body portion 31 is larger than in other parts, the mounting member 30 is welded more firmly at the leading edge of the main body portion 31.

[0062] In addition, during the spin welding process, resin reservoirs may not form on the sides of the main body portion 31 of the mounting member 30, resulting in the sides of the main body portion 31 not being welded to the resin reservoir or only being partially welded. Even in this case, since a resin reservoir with an arc-shaped cross-section is formed at the tip of the main body portion 31, the mounting member 30 is firmly fixed to the hollow plate material 11.

[0063] Furthermore, the head portion 34 of the mounting member 30 protrudes from the second skin layer 25 of the hollow plate material 11. The leading edge of the main body portion 31 of the mounting member 30 is not exposed from the outer surface of the first skin layer 24. In addition, the mounting member 30 is solid due to the molten resin that has entered the recess 32.

[0064] In the post-processing step, a through-instrument (not shown) having the same diameter as the recess 32 is inserted into the recess 32, which is filled with molten resin, from the tip surface 31a of the main body portion 31 of the mounting member 30. The through-instrument is moved from the tip surface 31a toward the head portion 34 of the mounting member 30 in the axial direction of the mounting member 30. This forms a through-hole 36 that penetrates the mounting member 30 in the axial direction.

[0065] Furthermore, the end of the mounting hole 36 that opens on the tip surface 31a is countersunk to form a housing portion 37 that accommodates the head 51a of the countersunk screw 51 of the fixing member 50. In this way, the hollow structure 10 is obtained through the welding process and post-processing process.

[0066] When attaching the hollow structure 10 to the inner wall of the jet engine 1, for example, a bending process of the hollow structure 10 to conform to the shape of the part of the inner wall where the hollow structure 10 will be placed may be performed following the post-processing process. The bending process is performed by preparing a pair of heating plates that conform to the shape of the part of the inner wall where the hollow structure 10 will be placed, and heating and deforming the hollow structure 10 by sandwiching it between the heated pair of heating plates. The heating temperature when heating and deforming the hollow structure 10 should be set to a few degrees Celsius higher than the melting point of the thermoplastic resin that makes up the hollow plate material 11. The heating time should be set to a few seconds to a little over ten seconds so that the hollow structure 10 is not heated for an excessively long time and melted.

[0067] <Regarding the function of the hollow structure 10> Next, the function of the hollow structure 10 will be explained. As shown in Figure 2, when attaching the hollow structure 10 to the nacelle 4, which is the inner wall of the jet engine 1, the hollow structure 10 is positioned facing the nacelle 4 with the mounting seat 41 and the mounting member 30 aligned. At this time, the main surface 10a on the side where the communication hole 12 is formed faces the air passage of the jet engine 1, and the main surface 10b on the side where the communication hole 12 is not formed faces the inner surface of the nacelle 4.

[0068] Next, a countersunk screw 51 is inserted into the mounting hole 36 of the mounting member 30 of the hollow structure 10 and screwed into the nut 52 fitted into the recess 42 of the mounting seat 41. The same procedure is followed for the multiple mounting members 30 fixed to the hollow structure 10. This completes the attachment of the hollow structure 10 to the nacelle 4.

[0069] In the hollow structure 10 attached to the nacelle 4, the leading edge of the mounting member 30 is not exposed on the main surface 10a facing the air passage. Furthermore, a housing portion 37 is formed in the mounting hole 36 of the mounting member 30 to accommodate the head 51a of the countersunk screw 51. As a result, the mounting member 30 and the fixing member 50 do not protrude from the main surface 10a facing the air passage, and the surface is flat. This makes it difficult for turbulence to occur in the airflow circulating inside the jet engine 1.

[0070] Furthermore, due to the spin welding process, a slight bulge may occur near the tip surface 31a of the mounting member 30 in the hollow structure 10 due to the molten resin being pressed by the mounting member 30. This slight bulge is not significant enough to affect airflow turbulence. The surface is considered flat even when this slight bulge occurs. In addition, although a groove is formed in the head 51a of the countersunk screw 51 for rotating the jig during installation, the surface is considered flat as long as the part other than the groove is flat.

[0071] Since the mounting member 30 is fixed to the hollow plate material 11 by spin welding, the molten resin of the core layer 20, first skin layer 24, and second skin layer 25 that make up the hollow plate material 11 are welded to the mounting member 30. As the mounting member 30 is firmly fixed inside the hollow plate material 11, the mounting state of the hollow structure 10 by the fixing member 50 is stabilized.

[0072] In the spin welding process, the positional relationship between the hollow plate material 11 and the mounting member 30 is difficult to define within the process. Therefore, the mounting member 30 is often welded across multiple cells S, as shown by mounting members 30a and 30b in Figure 11. Note that in Figure 11, the thickness of the side wall portion 23 of the cell S is omitted to make the positional relationship between the mounting member 30 and the cell S easier to understand. Also, Figure 11 shows the state in which the mounting member 30, which is locked to the spin welding machine, is moved downward so that the tip of the main body portion 31 of the mounting member 30 is in contact with the main surface 11b of the hollow plate material 11. Therefore, the main body portion 31 of the mounting member 30 is shown before it is inserted into the hollow plate material 11, and the side wall portion 23 of the cell S is shown maintaining its shape without being melted by heat.

[0073] In the case of mounting members 30a and 30b, during the spin welding process, the tip surface 31a of the mounting member 30 comes into contact with the side wall portion 23 of the core layer 20 at multiple points, causing the resin to melt due to heat. In other words, during the spin welding process, there are multiple welding points M between the mounting member 30 and the side wall portion 23 of the core layer 20. Subsequently, as the mounting member 30 moves downward, the side wall portion 23 of the core layer 20 melts starting from the welding points M.

[0074] On the other hand, as shown in the mounting member 30c in Figure 11, the mounting member 30 may be welded at a position where its axis coincides with the center of the cell S. In this embodiment, the diameter L3 at the center H1 in the height direction of the mounting member 30 is set to approximately 1.0 to 1.5 times the distance M1 between a pair of opposing side wall portions 23 in the cell S of the core layer 20. As shown in Figure 5, since the main body portion 31 is formed in a frustoconical shape with a larger diameter towards the base end, for example, even if the diameter L3 is 1.0 times the distance M1, the diameter will be larger than the distance M1 in about half of the base end of the main body portion 31. Therefore, even if it is welded at a position like the mounting member 30c, there will be multiple welded portions M with the side wall portions 23, and sufficient strength will be obtained as a hollow structure 10 to be attached to the nacelle 4.

[0075] In contrast, as shown by the mounting member 30d in Figure 11, if the mounting member 30 is positioned in the center of the cell S, and the diameter L3 is less than 1.0 times the distance M1, the welded portion M with the side wall portion 23 may not be formed. Therefore, in order to ensure sufficient strength as a hollow structure 10, it is necessary to fill the area around the mounting member 30 with a potting agent or the like. However, if the cell S is filled and sealed with a potting agent, it results in a decrease in sound absorption efficiency and an increase in weight, which is undesirable for aircraft engine components where high sound absorption efficiency and weight reduction are required.

[0076] In this embodiment, since the diameter L3 is set to approximately 1.0 to 1.5 times the distance M1, the necessary strength can be achieved when the hollow structure 10 is attached to the nacelle 4. The occlusion area due to the filling of potting agent can be kept to a minimum. In particular, when the diameter L3 is approximately 1.1 to 1.3 times the distance M1, the occlusion area due to the potting agent can be kept sufficiently small while welding to the side wall portion 23 within a range that provides sufficient strength.

[0077] Furthermore, it is preferable that there are approximately 3 to 10 welded portions M between the side surface of the main body 31 and the side wall portion 23. When the number of welded portions M is this small, sufficient strength is obtained as required for the hollow structure 10 attached to the nacelle 4 due to the accumulation of molten resin.

[0078] As the main body 31 of the mounting member 30 is inserted into the hollow plate material 11 while the hollow plate material 11 is heated and melted, the side wall portion 23 of the cell S may wrap around the mounting member 30 due to the rotation of the mounting member 30 during spin welding. A resin reservoir may form between the side wall portion 23 and the mounting member 30 to which it is wrapped. As the mounting member 30 is inserted, the cell S may not have a uniform hexagonal shape, but rather a distorted shape.

[0079] The flange portion 33 of the mounting member 30, which is formed to be thicker than the thickness of the second skin layer 25, is welded to the second skin layer 25. In addition, the tip surface 31a of the main body portion 31 of the mounting member 30 is formed as a flat surface and is welded to the inner surface of the first skin layer 24 in such a manner that it is not exposed from the first skin layer 24 of the hollow plate material 11. As a result, the flange portion 33 is firmly welded to the second skin layer 25, and the tip surface 31a is firmly welded to the first skin layer 24.

[0080] The hollow plate material 11 is a honeycomb structure in which multiple cells S are arranged side by side inside. In addition, in the hollow structure 10, multiple communication holes 12 are formed on the main surface 10a facing the air passage of the jet engine 1, connecting the inside and outside of the cells S. Therefore, noise generated in the air passage of the jet engine 1 is absorbed by the hollow structure 10.

[0081] According to this embodiment, the following effects can be obtained. (1) The main surface 10a of the hollow structure 10 does not expose the main body 31 of the mounting member 30, nor does the head 51a of the countersunk screw 51 of the fixing member 50 protrude. Therefore, when the hollow structure 10 is attached to the nacelle 4 so that the main surface 10a faces inward into the air passage, the surface of the hollow structure 10 facing inward into the air passage becomes a flat surface without any irregularities. This makes it possible to suppress turbulence of the air in the air passage.

[0082] (2) The side surface of the main body portion 31 of the mounting member 30 is welded to the side wall portion 23 of the core layer 20 of the hollow plate material 11. Therefore, the mounting member 30 is firmly fixed to the hollow plate material 11. When the hollow structure 10 is attached to the inner wall with the fixing member 50, the attachment state is stable.

[0083] (3) The leading edge of the main body portion 31 of the mounting member 30 is welded to the inner surface of the first skin layer 24 of the hollow plate material 11. As a result, the mounting member 30 is more firmly fixed to the hollow plate material 11.

[0084] (4) A flange portion 33 is formed at the base end of the main body portion 31 of the mounting member 30, extending radially. The flange portion 33 is welded to the second skin layer 25 of the hollow plate material 11. As a result, the mounting member 30 is fixed even more firmly to the hollow plate material 11.

[0085] (5) The main body 31 of the mounting member 30 has a mounting hole 36 that extends in the axial direction. Therefore, it is easy to insert the countersunk screw 51 into the mounting hole 36, and the installation of the hollow structure 10 can be easily performed.

[0086] (6) The main body portion 31 of the mounting member 30 has a recess 32 that opens to the tip surface 31a. During spin welding, the molten resin of the hollow plate material 11 enters the recess 32. As a result, the recess 32 provides an escape route for the molten resin that has been pushed by the main body portion 31, and deformation of the hollow plate material 11 around the mounting member 30 is suppressed.

[0087] (7) The main body 31 of the mounting member 30 has a frustoconical shape, which becomes slightly smaller in diameter towards the tip. Therefore, it is easier to move inside the hollow plate material 11 during spin welding compared to a cylindrical shape with a constant diameter.

[0088] (8) The tip side surface of the flange portion 33 of the mounting member 30 is formed as an inclined surface 33b that gradually decreases in diameter towards the tip. Therefore, it is easy to move inside the hollow plate material 11. (9) The diameter L3 at the center H1 in the height direction of the mounting member 30 is set to be approximately 1.0 to 1.5 times the distance M1 between a pair of opposing side walls 23 in the cell S of the core layer 20. Therefore, the necessary strength can be achieved when the hollow structure 10 is attached to the nacelle 4.

[0089] (10) The ratio (L1 / L2) of the diameter L1 of the base edge of the main body 31 to the diameter L2 of the tip surface 31a of the main body 31 is set to be greater than 1 and less than or equal to 2. This makes the spin welding process easier and ensures good positioning accuracy of the mounting member 30. Strong welding can be achieved with the side wall portion 23 of the core layer 20, ensuring the strength of the hollow structure 10.

[0090] (11) The angle between the base end surface 33a and the inclined surface 33b of the flange portion 33 is set to approximately 15 to 75 degrees. This facilitates the spin welding process and ensures good positioning accuracy of the mounting member 30. The strength of the hollow structure 10 can be ensured.

[0091] (12) In the hollow plate material 11 that constitutes the hollow structure 10, the inside and outside of the cell S are in communication through a plurality of communication holes 12. Therefore, it has excellent sound absorption performance. It can efficiently absorb noise generated in the air passage of the jet engine 1.

[0092] (13) The hollow structure 10 is a hollow member made of thermoplastic resin. Therefore, it is lightweight yet has excellent strength. When applied to the jet engine 1, it can contribute to weight reduction and durability.

[0093] (14) The manufacturing method of the hollow structure 10 includes a welding step in which the mounting member 30 is moved from one main surface 11b to the other main surface 11a of the hollow plate material 11 while the hollow plate material 11 and the mounting member 30 are rotated relative to each other. In the welding step, the mounting member 30 is welded to the inside of the hollow plate material 11 by the frictional heat generated between the hollow plate material 11 and the mounting member 30. As a result, the mounting member 30 is firmly fixed to the hollow plate material 11, and the mounting state of the hollow structure 10 to the nacelle 4 is stabilized.

[0094] (15) In the welding process, the mounting member 30 is moved and heat-welded within a range where the tip of the mounting member 30 is not exposed from the main surface 11a of the hollow plate material 11. This makes the main surface 10a of the hollow structure 10 a flat surface. If the main surface 10a side of the hollow structure 10 is installed on the side of the air passage of the jet engine 1, turbulence of the airflow inside the jet engine 1 can be suppressed.

[0095] (16) In the operating environment of aircraft engine components such as the nacelle 4, if the cut honeycomb structure is exposed, the rigidity is insufficient. To ensure rigidity, a potting agent or the like is sometimes poured in to seal the honeycomb structure. In this respect, in the hollow structure 10 of this embodiment, the sheet material 13 is welded to the side surface of the hollow plate material 11 to seal it. As a result, the cells S on the side surface of the hollow plate material 11 are not exposed, and the strength and rigidity of the hollow structure 10 are improved. In addition, since the sheet material is lightweight, it is possible to suppress the weight increase that occurs when a potting agent is filled in.

[0096] The above embodiment can be modified as follows. The above embodiment and the following modifications can be combined and applied to the extent that they do not contradict each other technically. As shown in Figure 12, the mounting member 30 does not necessarily have to be welded to the first skin layer 24. It is sufficient that the side surface of the main body portion 31 of the mounting member 30 is welded to the side wall portion 23 of the core layer 20, and the flange portion 33 is welded to the second skin layer 25. In this case, during the welding process, the mounting member 30 is moved to a position where the tip surface 31a of the mounting member 30 does not come into contact with the first skin layer 24.

[0097] As shown in Figure 13, the mounting member 30 does not necessarily have to have a flange portion 33. The mounting member 30 does not need to have a recess 32 formed in it before it is attached to the hollow plate material 11.

[0098] • Before being attached to the hollow plate material 11, the mounting member 30 may have a hole that penetrates vertically instead of a recess 32. In this case, during the post-processing step, a penetrating tool of the same diameter as the hole can be inserted into the hole into which the molten resin has entered to form the mounting hole 36.

[0099] The mounting member 30 does not necessarily need to have a head 34 formed on it. The mounting member 30 does not have to be frustoconical in shape. For example, it may be cylindrical in shape, where the diameter does not change from the tip to the base. Alternatively, the base end may be cylindrical and the tip end may be conical.

[0100] The shape of the tip of the mounting member 30 is not particularly limited. It does not have to be a flat tip surface 31a; for example, it may be hemispherical. As shown in Figure 5, the tip surface 31a of the mounting member 30 is a planar surface that is substantially parallel to the base end surface 33a of the flange portion 33 and the base end surface of the head portion 34, but is not limited to this. The tip surface 31a may be an inclined surface that is inclined with respect to the base end surface 33a of the flange portion 33 and the base end surface of the head portion 34. For example, as shown in Figure 18, it may be an inclined surface 31b that connects the side surface of the main body portion 31 of the mounting member 30 and the opening of the recess 32.

[0101] The tip corners of the mounting member 30 may be chamfered with a C-chamfer or R-chamfer. Specifically, the boundary between the side surface of the main body 31 of the mounting member 30 and the tip surface 31a may be chamfered or R-shaped.

[0102] In the figures of the above embodiments, the base end surface of the head 34 of the mounting member 30 is shown as a flat surface. However, a recess may be formed in the center of the base end surface of the head 34, which is recessed toward the tip. The formation of the recess allows for more reliable vacuum fixing of the spin welding machine during the spin welding process. Furthermore, after fixing the mounting member 30 to the hollow plate material 11, the positioning of the tip of the through-hole can be easily performed in the post-processing step of forming the mounting hole 36 in the mounting member 30.

[0103] Four locking holes 35 are formed in the base end face 33a of the flange portion 33 of the mounting member 30. However, the number of locking holes 35 is not limited to this. Also, the position of the locking holes 35 is not particularly limited as long as it corresponds to the position of the spin welding machine used. Preferably, the position of the locking holes 35 is, for example, inside the outer diameter of the main body portion 31 of the mounting member 30. When formed in such a position, the force from the spin welding machine is easily transmitted to the mounting member 30 during the spin welding process.

[0104] The mounting member 30, after being attached to the hollow structure 10, does not necessarily need to have a mounting hole 36 that penetrates axially. In this case, it can be attached to the nacelle 4 by means other than the countersunk screw 51 and nut 52, such as adhesive.

[0105] The mounting member 30 does not necessarily need to have a housing portion 37 formed on it after it has been attached to the hollow plate material 11. In this case, it can be attached with a screw of a different shape than the countersunk screw 51. The mounting member 30 attached to the hollow structure 10 is welded such that the base end surface 33a of the flange portion 33 is flush with the outer surface of the second skin layer 25, but the mounting state of the mounting member 30 is not limited to this. The base end surface 33a of the flange portion 33 may protrude from the outer surface of the second skin layer 25, and a step may be formed between the base end surface 33a and the outer surface of the second skin layer 25.

[0106] In the above embodiment, the thickness of the flange portion 33 of the mounting member 30 is greater than the thickness of the second skin layer 25, but it may be thinner than the thickness of the second skin layer 25. In this case, the entire circumference of the flange portion 33 can be firmly welded within the thickness of the second skin layer 25.

[0107] The fixing member 50 does not have to be a countersunk screw 51 and a nut 52. For example, the head 34 of the mounting member 30 may be provided with an engaging portion that engages with the mounting seat 41 of the nacelle 4. • The hollow plate material 11 does not necessarily need to have a communication hole 12 formed in it.

[0108] The communication holes 12 do not necessarily have to be formed in one location per cell S. For example, cells S with communication holes 12 and cells S without communication holes 12 may be mixed together. In this case, the cells S to which the mounting member 30 is welded may include cells S with communication holes 12 and cells S without communication holes 12.

[0109] The communication hole 12 does not have to be located in the center of cell S. In the above embodiments and the figures illustrating them, the hollow structure 10 was described as being planar. However, the hollow structure 10 does not have to be planar. As shown in Figure 14, it may be curved to conform to the inner surface shape of the nacelle 4. Furthermore, only a part of it may be curved.

[0110] In the above embodiment, it was explained that the main surface 10a of the hollow structure 10 attached to the nacelle 4 that faces the air passage is a flat surface with no protrusions from the mounting member 30 or fixing member 50. However, for example, if the hollow structure 10 is curved as shown in Figure 14, the head 51a of the countersunk screw 51 attached to the mounting member 30 may protrude slightly. In this case, the amount of protrusion of the countersunk screw 51 is acceptable as long as it does not cause turbulence in the airflow.

[0111] As shown in Figure 14, the tip surface 31a of the main body 31 of the mounting member 30 may be welded at an angle to the first skin layer 24 of the hollow plate material 11. In this case, the amount of resin pooling at the tip side of the tip surface 31a of the main body 31 formed during spin welding will be greater where the distance between the tip surface 31a and the first skin layer 24 is shorter. To illustrate with Figure 14, the left side of the tip surface 31a of the main body 31 of the mounting member 30 has more resin pooling than the right side of Figure 14. This ensures that the mounting member 30 is securely welded. Even if there is a possibility of a low resin density area forming between the tip of the mounting member 30 and the first skin layer 24, the mounting member 30 is firmly welded to the hollow plate material 11.

[0112] As shown in Figure 14, if the tip surface 31a of the main body portion 31 of the mounting member 30 is inclined with respect to the first skin layer 24, it is preferable to use a mounting member 30 having an inclined surface 31b as shown in Figure 18. In this case, it is preferable to weld the mounting member 30 in such a state that the inclined surface 31b is parallel to the first skin layer 24.

[0113] In the hollow structure 10 of the above embodiment, the base end surface 33a of the flange portion 33 of the mounting member 30 is flush with the main surface 10b of the hollow plate material 11. However, the mounting position of the mounting member 30 is not limited to this. As shown in Figure 15, the mounting member 30 may be welded in the spin welding process so that the main surface 11b of the hollow plate material 11 aligns with the intermediate position of the flange portion 33 in the thickness direction. In this case, as shown by the dashed line in Figure 15, the portion protruding from the main surface 11b may be cut along the main surface 11b.

[0114] As shown in Figure 16, if the hollow structure 10 is curved, the mounting member 30 may be mounted in a shape that is inclined with respect to the main surface 11b of the hollow plate material 11. For example, at the base end side of the mounting member 30, a part of the base end surface 33a of the flange portion 33 may be flush with the main surface 11b of the hollow plate material 11, while another part may protrude from the main surface 11b of the hollow plate material 11.

[0115] As shown in Figure 17, when the hollow structure 10 is curved, at the base end of the mounting member 30, a portion of the base end surface 33a of the flange portion 33 may be flush with the main surface 11b of the hollow plate material 11, while another portion may be located inward from the main surface 11b of the hollow plate material 11. In this case, in the portion of the base end surface 33a located inward from the main surface 11b, the main surface 10b of the hollow structure 10 becomes recessed, forming a recess 10c.

[0116] The hollow plate material 11 is not limited to being formed by folding and molding a single first sheet material 100 to constitute the core layer 20; it may also be formed using multiple sheets. For example, the core layer 20 may be formed by bending strip-shaped sheets at predetermined intervals and arranging multiple bent strip-shaped sheets side by side.

[0117] The core layer 20 of the hollow plate material 11 is not limited to being formed by folding or bending a sheet. A honeycomb structure consisting only of the side wall portions 23 may be injection molded. The core layer 20 may be without at least one of the upper wall portion 21 and the lower wall portion 22.

[0118] The core layer 20 has hexagonal prism-shaped cells S partitioned inside, but the shape of the cells S is not particularly limited. For example, they may be polygonal shapes such as rectangular prisms or octagonal prisms, or cylindrical shapes. In this case, cells of different shapes may be mixed together. Also, the cells do not have to be adjacent to each other, and gaps (spaces) may exist between the cells.

[0119] - As the hollow plate material 11, for example, a core layer 20 may be formed by providing a plurality of hollow cylindrical cells that protrude toward one side from a sheet-like sheet body, and the first skin layer 24 and the second skin layer 25 may be joined to the top surfaces of the hollow cylindrical cells in the core layer 20. Alternatively, the core layer 20 may be constructed by joining sheets, each having a plurality of hollow cylindrical cells, such that the top surfaces of the hollow cylindrical cells are joined together. In this case, the first skin layer 24 and the second skin layer 25 will be joined to the surface on which no hollow cylindrical cells are formed in at least one of the sheets having a plurality of hollow cylindrical cells. Note that the term "hollow cylindrical" as used herein is not limited to those with a constant diameter in the height direction, but also includes tapered hollow cylindrical shapes (prefixed cone shapes) where the diameter decreases towards the top surface.

[0120] The first skin layer 24 and the second skin layer 25 may not be single-layer structures, but rather laminates of two or more layers. For example, a resin layer other than polyamide resin, such as an acrylic layer, can be formed on the outer surface of the first skin layer 24 to improve scratch resistance or impact resistance. The layer structures of the first skin layer 24 and the second skin layer 25 may be different.

[0121] In the above embodiment, the thickness of the first sheet material 100 for forming the core layer 20, and the thickness of the second sheet material for forming the first skin layer 24 and the second skin layer 25 are not particularly limited. It is preferable that the thickness of each of these layers be in the order of first skin layer 24 > second skin layer 25 > first sheet material 100.

[0122] If the first skin layer 24 and the second skin layer 25 are thicker than the first sheet material 100, the rigidity of both sides of the hollow structure 10 is improved, and the overall rigidity of the hollow structure 10 can be improved. Furthermore, if the first skin layer 24 is thicker than the second skin layer 25, the impact strength of the hollow structure 10 facing inward into the air passage of the jet engine 1 can be ensured. In addition, it becomes easier to insert the mounting member 30 during the spin welding process. Moreover, during the spin welding process, the mounting member 30 is less likely to be exposed on the outside of the first skin layer 24, and the surface of the first skin layer 24 is easier to flatten.

[0123] In the hollow structure 10, the sheet material 13 is welded to the side surface of the hollow plate material 11 to seal it, but this is not the only option. For example, to allow for drainage of water from inside the cell S, some side surfaces may be left unsealed. Alternatively, the side surfaces may be sealed and drainage holes may be formed on the side surfaces.

[0124] In the manufacturing method of the hollow structure 10, prior to the welding process, a recess or hole for attaching the mounting member 30 may be formed in the portion of the hollow plate material 11 to which the mounting member 30 will be attached. The recess or hole shall have a smaller diameter than the main body portion 31 of the mounting member 30. In this case as well, frictional heat can be generated between the hollow plate material 11 and the mounting member 30 during spin welding.

[0125] In the post-processing step for manufacturing the hollow structure 10, a through-hole with the same diameter as the recess 32 was inserted into the recess 32, which was filled with molten resin, from the tip surface 31a side of the main body portion 31 of the mounting member 30, to form the mounting hole 36. To form the mounting hole 36, a through-hole with a larger diameter than the recess 32 may be used instead of one with the same diameter as the recess 32. In this case, since the mounting hole 36 is formed with a larger diameter than the recess 32, resin residue is less likely to be generated from the molten resin that has entered the recess 32 when fixing the countersunk screw 51, etc. [Explanation of Symbols]

[0126] S, S1, S2... Cells 4… Nacelle (the inner wall of a jet engine) 10...Hollow structure 11...Hollow plate material 20…Core Layer 23... Side wall section 24…First Skin Layer 25...Second Skin Layer 30…Mounting parts 31...Main body 33…Flange section 36…Mounting holes

Claims

1. A hollow structure configured to be attached and fixed to the inner wall of the jet engine of an aircraft to be mounted, A hollow plate material made of thermoplastic resin with multiple cells arranged side by side inside, It comprises a mounting member configured to be attached and fixed to the inner wall, The aforementioned hollow plate material is A core layer having a plurality of side wall portions that extend in the thickness direction of the hollow plate material and divide a plurality of the cells, A first skin layer is laminated on the first main surface of the core layer, A second skin layer laminated on the second main surface of the core layer and Equipped with, The mounting member comprises a columnar main body extending in the thickness direction of the hollow plate material, The side surface of the main body is welded to the side wall of the core layer. The main body portion is a hollow structure characterized in that it is not exposed from the outer surface of the first skin layer.

2. The hollow structure according to claim 1, characterized in that the main body portion has an edge that is welded to the inner surface of the first skin layer.

3. The main body portion has an end portion that has a flange portion that protrudes radially, The hollow structure according to claim 1, characterized in that the flange portion is welded to the second skin layer.

4. The hollow structure according to any one of claims 1 to 3, characterized in that the main body portion has a mounting hole extending in the axial direction.

5. A method for manufacturing a hollow structure comprising a hollow plate material made of thermoplastic resin with multiple cells arranged in parallel inside, and a columnar mounting member configured to be attached and fixed to the inner wall of a jet engine, The welding process includes a step in which the mounting member is welded to the interior of the hollow plate by frictional heat generated between the hollow plate and the mounting member, while the mounting member is moved from the first main surface to the second main surface of the hollow plate while the hollow plate and the mounting member are rotated relative to each other, A method for manufacturing a hollow structure, characterized in that, in the welding step, the mounting member is moved within a range in which the mounting member is not exposed from the second main surface.

Images