Aluminum alloy hollow extruded member

Abstract

To provide an aluminum alloy hollow extrusion member having a weld metal zone in which user's quality misrecognition is restricted.SOLUTION: An aluminum alloy hollow extrusion member 1 of this invention is an aluminum alloy hollow extrusion member, which has: a hollow body extending in a longitudinal direction matching with an extrusion direction upon extrusion molding and making the cross section cut vertically to the longitudinal direction include a polygonal shape; and N pieces of weld metal zones each of which extends along the longitudinal direction so that the hollow body may be partitioned into N pieces (N is an integer of two or more) of parts in a direction going around the cross section. The hollow body has: M pieces (M is an integer of three of more) of wall parts, each of which is tabular with a predetermined thickness, and each of which is arranged so as to form each side of the cross section; and M pieces of connections, each of which connects the wall parts adjacent to each other and is arranged so as to form each angle of the cross section. At least one piece of the weld metal zones is allotted to the connection in the cross section.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an aluminum alloy hollow extrusion member.

Background Art

[0002] An aluminum alloy hollow extrusion member, which is a hollow extrusion molded product of an aluminum alloy, is a lightweight and high-strength member, and thus is widely used in various technical fields. For example, as a member for an automobile (e.g., a door beam) for the purpose of impact absorption or the like, a hollow aluminum alloy hollow extrusion member having a rectangular cross section is used.

[0003] This type of aluminum alloy hollow extrusion member is manufactured, for example, by a porthole extrusion method which is a kind of extrusion molding. The porthole extrusion method is a method using a porthole die in which a male die having a mandrel portion at the center of the tip of a plurality of portholes divided by a bridge, a die portion, and a female die having a chamber around it are combined. When a billet is pushed into the porthole die, the billet is divided into a plurality along the extrusion direction by the plurality of portholes of the male die. When the plurality of members formed by dividing the billet are extruded so as to surround the mandrel portion from the gap between the mandrel portion of the male die and the die portion of the female die, they are welded and integrated. Then, the inner surface of the member in the welded and integrated state is formed by the mandrel portion, and the outer surface thereof is formed by the die portion, whereby a hollow aluminum alloy hollow extrusion member is obtained. Such a porthole extrusion method is often used for manufacturing an aluminum alloy hollow extrusion member because it is easy to maintain a uniform wall thickness and, moreover, can relatively suppress the manufacturing cost.

[0004] Incidentally, hollow extruded aluminum alloy members manufactured by the porthole extrusion method inevitably have welded joints formed along the extrusion direction (longitudinal direction) (Patent Documents 1 and 2). These welded joints are formed when multiple members formed by dividing a billet during manufacturing are welded together. For example, if the hollow extruded aluminum alloy member is a longitudinal hollow body having a pair of plate-shaped flanges and a pair of plate-shaped webs, the welded joints are formed straight along the longitudinal direction on the plate surfaces of the flanges and the webs (Patent Documents 1 and 2). Furthermore, in a cross-section of the hollow extruded aluminum alloy member cut perpendicular to the longitudinal direction, the welded joints are formed straight across the plate thickness direction of the flanges and the plate thickness direction of the webs. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6322329 [Patent Document 2] Patent No. 6452878 [Overview of the project] [Problems that the invention aims to solve]

[0006] When users of hollow extruded aluminum alloy components see the welded areas on the components, they may intuitively mistakenly perceive the area near the weld as being weaker than the rest of the component, even though the area near the weld is not weaker than the rest of the component. Furthermore, if the welded area is located in a prominent part of the product, users may mistakenly perceive the entire product as being weaker.

[0007] The object of the present invention is to provide an aluminum alloy hollow extruded member having a welded portion that suppresses user misinterpretation of quality. [Means for solving the problem]

[0008] The means to solve the aforementioned problem are as follows: <1> An aluminum alloy hollow extruded member having a hollow body extending in a longitudinal direction corresponding to the extrusion direction during extrusion molding, and the cross section obtained by cutting perpendicular to the longitudinal direction includes a polygonal shape, and N welded portions extending along the longitudinal direction, each dividing the hollow body into N portions (N is an integer of 2 or more) in a direction circumferential to the cross section, wherein the hollow body has M wall portions (M is an integer of 3 or more) that are plate-shaped and each has a predetermined thickness, and each has a wall portion that forms each side of the cross section, and M connecting portions that each has a corner of the cross section and each has a connecting portion that connects adjacent wall portions, and at least one of the welded portions is assigned to the connecting portion in the cross section.

[0009] <2> N ≤ M, and all N of the aforementioned welding portions are assigned to the connection portion. <1> The aluminum alloy hollow extruded member described above.

[0010] <3> The hollow body has plate-shaped partition walls that divide the space inside the M wall portions. <1> also <2> The aluminum alloy hollow extruded member described above.

[0011] <4> The hollow body is bent so that its longitudinal direction is curved. <1> ~ <3> A hollow extruded aluminum alloy member as described in any one of the following.

[0012] <5> The wall portion in which the welded portion is not formed <1> ~ <4> A hollow extruded aluminum alloy member as described in any one of the following. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an aluminum alloy hollow extruded member having a welded portion that suppresses user misinterpretation of quality. [Brief explanation of the drawing]

[0014] [Figure 1]Perspective view of the aluminum alloy hollow extrusion member according to Embodiment 1 [Figure 2] Cross-sectional view taken along the α-α line of FIG. 1 [Figure 3] Explanatory drawing of the aluminum alloy hollow extrusion member used as a door beam for a vehicle door [Figure 4] Partial cross-sectional view of the aluminum alloy hollow extrusion member according to Embodiment 2 cut perpendicular to the longitudinal direction [Figure 5] Partial cross-sectional view of the aluminum alloy hollow extrusion member according to Embodiment 3 cut perpendicular to the longitudinal direction [Figure 6] Partial cross-sectional view of the aluminum alloy hollow extrusion member according to Embodiment 4 cut perpendicular to the longitudinal direction [Figure 7] Partial cross-sectional view of the aluminum alloy hollow extrusion member according to Embodiment 5 cut perpendicular to the longitudinal direction [Figure 8] Perspective view of the aluminum alloy hollow extrusion member according to Embodiment 6 [Figure 9] Cross-sectional view taken along the β-β line of FIG. 8 [Figure 10] Perspective view of the aluminum alloy hollow extrusion member according to Embodiment 7 [Figure 11] Perspective view of the aluminum alloy hollow extrusion member according to Comparative Example 1 [Figure 12] Perspective view of the aluminum alloy hollow extrusion member according to Comparative Example 2

Modes for Carrying Out the Invention

[0015] <Embodiment 1> The aluminum alloy hollow extrusion member 1 according to Embodiment 1 of the present invention will be described while referring to FIGS. 1 to 3. FIG. 1 is a perspective view of the aluminum alloy hollow extrusion member 1 according to Embodiment 1, and FIG. 2 is a cross-sectional view taken along the line α-α of FIG. 1. The aluminum alloy hollow extrusion member 1 is a hollow member having a square cross-section (so-called square tube) made of aluminum alloy manufactured by the porthole extrusion method. As is well known, the porthole extrusion method is a kind of extrusion molding method that uses a porthole die that combines a male die having a mandrel part at the center of the tip of a plurality of portholes divided by a bridge, a die part, and a female die having a chamber around it.

[0016] The aluminum alloy hollow extrusion member 1 extends in the longitudinal direction L corresponding to the extrusion direction during extrusion molding, and has a hollow body 2 whose cross-section 2a cut perpendicular to the longitudinal direction L is square (square shape) (an example of a polygonal shape), and four (an example of N. N is an integer of 2 or more) welding parts 3 that extend along the longitudinal direction so that the hollow body 2 is divided into four parts (an example of N. N is an integer of 2 or more) in the direction around the cross-section 2a.

[0017] The hollow body 2 has four (an example of M. M is an integer of 3 or more) wall parts 4 each having a predetermined thickness and arranged so as to form each side of the cross-section 2a, and four (an example of M. M is an integer of 3 or more) connection parts 5 each arranged so as to form each corner of the cross-section 2a and connecting the adjacent wall parts 4 to each other. Further, the hollow body 2 has a hollow part 6 extending in the longitudinal direction inside the hollow body surrounded by the four wall parts 4. In the case of the present embodiment, N ≤ M.

[0018] In the cross-section 2a of the aluminum alloy hollow extrusion member 1 shown in FIG. 2, among the four wall parts 4, the one arranged on the upper side is called the "first wall part 41", the one arranged on the lower side is called the "second wall part 42", the one arranged on the left side is called the "third wall part 43", and the one arranged on the right side is called the "fourth wall part 44".

[0019] As shown in Figure 1, the first wall section 41 and the second wall section 42 each extend horizontally and are arranged parallel to each other in the vertical direction, maintaining a distance between them. Similarly, as shown in Figure 1, the third wall section 43 and the fourth wall section 44 each extend vertically and are arranged parallel to each other in the horizontal direction, maintaining a distance between them.

[0020] In this embodiment, the thicknesses (plate thicknesses) of the first wall portion 41 and the second wall portion 42 are set to be the same as the thicknesses (plate thicknesses) of the third wall portion 43 and the fourth wall portion 44. In other embodiments, the thicknesses (plate thicknesses) of the first wall portion 41 and the second wall portion 42 may be set to be smaller than the thicknesses (plate thicknesses) of the third wall portion 43 and the fourth wall portion 44, or the thicknesses (plate thicknesses) of the first wall portion 41 and the second wall portion 42 may be set to be larger than the thicknesses (plate thicknesses) of the third wall portion 43 and the fourth wall portion 44, as long as the objective of the present invention is not impaired. Furthermore, the thicknesses of each wall portion 4 may be different from each other.

[0021] Furthermore, in this embodiment, the lengths of the first wall portion 41 and the second wall portion 42 in the short direction (direction perpendicular to the longitudinal direction) are set to be the same as the lengths of the third wall portion 43 and the fourth wall portion 44 in the short direction. In other embodiments, the lengths of the first wall portion 41 and the second wall portion 42 in the short direction may be set to be longer than the lengths of the third wall portion 43 and the fourth wall portion 44 in the short direction (i.e., the cross-section may be a horizontally elongated rectangle), or the lengths of the first wall portion 41 and the second wall portion 42 in the short direction may be set to be shorter than the lengths of the third wall portion 43 and the fourth wall portion 44 in the short direction (i.e., the cross-section may be a vertically elongated rectangle).

[0022] Furthermore, in the cross-section 2a of the aluminum alloy hollow extruded member 1 shown in Figure 2, of the four connecting parts 5, the one forming the upper left corner and connecting the adjacent first wall portion 41 and third wall portion 43 is referred to as the "first connecting part 51", the one forming the upper right corner and connecting the adjacent first wall portion 41 and fourth wall portion 44 is referred to as the "second connecting part 52", the one forming the lower left corner and connecting the adjacent third wall portion 43 and second wall portion 42 is referred to as the "third connecting part 53", and the one forming the lower right corner and connecting the adjacent fourth wall portion 44 and second wall portion 42 is referred to as the "fourth connecting part 54".

[0023] In Figure 2, for the sake of explanation, the boundaries between each wall section 4 and each connection section 5 are shown with dashed lines. For example, the boundary L1 between the first wall section 41 and the first connection section 51 lies on the extension of the inner wall surface 43a of the third wall section 43 adjacent to the first wall section 41, and the boundary L2 between the third wall section 43 and the first connection section 51 lies on the extension of the inner wall surface 41a of the first wall section 41 adjacent to the third wall section 43. Also, the boundary L3 between the first wall section 41 and the second connection section 52 lies on the extension of the inner wall surface 44a of the fourth wall section 44 adjacent to the first wall section 41, and the boundary L4 between the fourth wall section 44 and the second connection section 52 lies on the extension of the inner wall surface 41a of the first wall section 41 adjacent to the fourth wall section 44.

[0024] Furthermore, the boundary L5 between the second wall portion 42 and the third connecting portion 53 lies on the extension of the inner wall surface 43a of the third wall portion 43 adjacent to the second wall portion 42, and the boundary L6 between the third wall portion 43 and the third connecting portion 53 lies on the extension of the inner wall surface 42a of the second wall portion 42 adjacent to the third wall portion 43. Also, the boundary L7 between the second wall portion 42 and the fourth connecting portion 54 lies on the extension of the inner wall surface 44a of the fourth wall portion 44 adjacent to the second wall portion 42, and the boundary L8 between the fourth wall portion 44 and the fourth connecting portion 54 lies on the extension of the inner wall surface 42a of the second wall portion 42 adjacent to the fourth wall portion 44.

[0025] As shown in Figure 2, the cross-section 2a of the hollow extruded aluminum alloy member 1 is square in shape overall, due to the four wall portions 4 and the four connecting portions 5.

[0026] Furthermore, the hollow extruded aluminum alloy member 1 of this embodiment is used as a door beam, as will be described later.

[0027] In the cross-section 2a of such an aluminum alloy hollow extruded member 1, the four welded portions 3 are each inclined with respect to the thickness direction of the wall portion 4, and are arranged radially as a whole, with one allocated to each connecting portion 5. In other words, in such an aluminum alloy hollow extruded member 1, at least one of the four (N) welded portions 3 is allocated to a connecting portion 5 in the cross-section 2a. In particular, in this embodiment, N ≤ M, and all four (N) welded portions 3 are allocated to four (M) connecting portions 5.

[0028] The welded portion 3 is a manufacturing mark that is inevitably formed on the hollow extruded aluminum alloy member 1 manufactured by the porthole extrusion method. During manufacturing, the billet (aluminum alloy billet) is divided into multiple parts along the extrusion direction by multiple port holes in the male die. The multiple parts formed by the division of the billet are welded together as they are extruded from the gap between the mandrel portion of the male die and the die portion of the female die, surrounding the mandrel portion. In this way, the welded and integrated portion is formed as the welded portion 3 on the final extruded product, the hollow extruded aluminum alloy member 1.

[0029] Each welded portion 3 extends inclined with respect to the thickness direction of the wall portion 4, from the boundary portion of adjacent wall portions 4 on the inside of the hollow body 2 toward the corner portion of the connection portion 5 on the outside of the hollow body 2, at the corresponding connecting portion 5.

[0030] The welded portion 3 (first welded portion 31) formed on the first connecting portion 51 is formed so as to diagonally cross the first connecting portion 51 when viewed in cross-section. Of the first welded portion 31, the end portion 31a that is located on the inside of the hollow body 2 is located at the boundary between the first wall portion 41 and the third wall portion 43, and the end portion 31b that is located on the outside of the hollow body 2 is located at the corner portion 51b of the first connecting portion 51.

[0031] The welded portion 3 (second welded portion 32) formed on the second connecting portion 52 is formed so as to diagonally cross the second connecting portion 52 when viewed in cross-section. Of the second welded portion 32, the end portion 32a that is located on the inside of the hollow body 2 is located at the boundary between the first wall portion 41 and the fourth wall portion 43, and the end portion 32b that is located on the outside of the hollow body 2 is located at the corner portion 52b of the second connecting portion 52.

[0032] The welded portion 3 (third welded portion 33) formed on the third connecting portion 53 is formed so as to diagonally cross the third connecting portion 53 when viewed in cross-section. Of the third welded portion 33, the end portion 33a that is located on the inside of the hollow body 2 is located at the boundary between the second wall portion 42 and the third wall portion 43, and the end portion 33b that is located on the outside of the hollow body 2 is located at the corner portion 53b of the third connecting portion 53.

[0033] The welded portion 3 (fourth welded portion 34) formed on the fourth connecting portion 54 is formed so as to diagonally cross the fourth connecting portion 54 when viewed in cross-section. Of the fourth welded portion 34, the end portion 34a that is located on the inside of the hollow body 2 is located at the boundary between the second wall portion 43 and the fourth wall portion 44, and the end portion 34b that is located on the outside of the hollow body 2 is located at the corner portion 54b of the fourth connecting portion 54.

[0034] These four welded portions 3 divide the hollow extruded aluminum alloy member 1 into four sections S1, S2, S3, and S4 in the direction circumferential to the square-shaped cross-section 2a. Section S1 consists of a first wall portion 41, a part of the first connecting portion 51, and a part of the second connecting portion 52. Section S2 consists of a fourth wall portion 44, the other part of the second connecting portion 52, and a part of the fourth connecting portion 54. Section S3 consists of a second wall portion 42, a part of the third connecting portion, and the other part of the fourth connecting portion. Section S4 consists of a third wall portion 43, the other part of the first connecting portion 51, and the other part of the third connecting portion. Each of the divided sections S1, S2, S3, and S4 is integrally connected to one another, with the welded portions 3 serving as the interface.

[0035] Furthermore, the ends 31b, 32b, 33b, and 34b of each welded portion 3 located on the outside of the hollow body 2 are positioned at the corresponding corners 51b, 52b, 53b, and 54b of the connecting portion 5. As a result, the ends 31b, 32b, 33b, and 34b of each welded portion 3 are not conspicuous when the aluminum alloy hollow extruded member 1 is viewed from the outside. In other embodiments, the corners of the connecting portion 5 may be chamfered to give them a rounded shape, and the ends 31b, 32b, 33b, and 34b of each welded portion 3 may be positioned at such corners.

[0036] Furthermore, in order to position each welded portion 3 at a desired location in the hollow body 2 as described above, the shape of the port hole die used during manufacturing (for example, the shape of the male port hole) is set appropriately. The technique for appropriately setting the shape of the port hole die is well known, and therefore a detailed explanation thereof is omitted in this specification.

[0037] Figure 3 is an explanatory diagram of an aluminum alloy hollow extruded member 1 used as a door beam for a vehicle door. Figure 3 shows the cross-sectional configuration of the aluminum alloy hollow extruded member 1, etc., cut in the vehicle width direction. The left and right directions in Figure 3 correspond to the vehicle width direction. As shown in Figure 3, the aluminum alloy hollow extruded member 1, which is the door beam, is attached to an inner panel 12 provided inside the vehicle door. The inner panel 12 is provided along the vertical direction inside the vehicle door, and the aluminum alloy hollow extruded member 1 is attached to its surface 12a facing the outside of the vehicle interior using mounting means 10. The left side of Figure 3 is the vehicle interior side (inside the vehicle interior), and the right side of Figure 3 is the outside of the vehicle interior. The hollow extruded aluminum alloy member 1 has a pair of vertically extending wall portions 4 (first wall portion 41 and second wall portion 42) arranged side by side in the vehicle width direction, with one wall portion 4 (second wall portion 42) positioned on the interior side of the vehicle and the other wall portion 4 (first wall portion 41) positioned on the exterior side of the vehicle. The wall portion 4 (second wall portion 42) positioned on the interior side of the vehicle is fixed to the inner panel 12 using mounting means (e.g., bolts and nuts) 10, thereby fixing the hollow extruded aluminum alloy member 1 to the inner panel 12. Approximately in the center of the wall portion 4 (second wall portion 42) positioned on the interior side of the vehicle, there is a hole 11 that penetrates in the thickness direction, and the mounting means 12 is attached by being inserted through this hole 11 and a hole 13 provided in the inner panel 12 that penetrates in the thickness direction. In this state of the hollow extruded aluminum alloy member 1, the pair of wall portions 4 (third wall portion 43 and fourth wall portion 44) extending in the left-right direction are arranged to be parallel to each other in the vertical direction.

[0038] As described above, the hollow extruded aluminum alloy member 1 used as a door beam can absorb the impact during a side collision of the vehicle. Furthermore, when attaching the hollow extruded aluminum alloy member 1 to the inner panel 12, the worker (user) can perform the installation work without worrying about the presence of the welded portion 3.

[0039] In this embodiment, the welded portion 3 is formed to connect the boundary portion between adjacent wall portions 4 on the inside of the hollow body 2 and the corner portion of the connecting portion 5 on the outside of the hollow body 2 when viewed in cross-section. For example, the first welded portion 31 is formed to connect the boundary portion between adjacent first wall portions 41 and third wall portions 43 and the corner portion 51b of the first connecting portion 51.

[0040] By positioning the ends of each welded portion 3 on the outside of the hollow body 2 at the corresponding corners of the connecting portions 5, the welded portions 3 can be made less conspicuous when the aluminum alloy hollow extruded member 1 is viewed from the outside. This also helps to suppress misidentification of quality even in anodized aluminum alloy hollow extruded member 1 where the welded portions 3 are more noticeable.

[0041] Furthermore, while forming the welded portion 3 so as to connect the boundary between adjacent wall portions 4 and the corner of the connecting portion 5 is preferable from the viewpoint of making the welded portion 3 less conspicuous, as described above, the position of the welded portion 3 formed on the connecting portion 5 may be slightly changed for manufacturing or other reasons, in order to make the welded portion 3 less conspicuous. Below, with reference to Figures 4 to 7, other embodiments in which the formation position of the welded portion 3 in Embodiment 1 is changed will be described.

[0042] <Embodiment 2> Embodiment 2 relates to an aluminum alloy hollow extruded member 1A, which is a modification of Embodiment 1. Figure 4 is a partial cross-sectional view of the aluminum alloy hollow extruded member 1A according to Embodiment 2, cut perpendicular to the longitudinal direction. The aluminum alloy hollow extruded member 1A of Embodiment 2 comprises a hollow body 2 with the same configuration as in Embodiment 1. In Figure 4, each component of the hollow body 2 is denoted by the same reference numerals as in Embodiment 1. In this embodiment, the formation position of the welded portion 3A is different from that of Embodiment 1. Here, we will explain using the case where the position in which the first welded portion 3A is formed on the first connecting portion 51 is changed as an example.

[0043] The first welded portion 31A extends diagonally across the first connecting portion 51 in a cross-sectional view of the aluminum alloy hollow extruded member 1A, inclined with respect to the thickness direction of the wall portion 4. However, the position of the end portion 31Ab of the welded portion 3A, which is located on the outside of the hollow body 2, differs from that of Embodiment 1. Specifically, the end portion 31Ab is formed to be located away from the corner portion 51b of the first connecting portion 51 and closer to the first wall portion 41 (closer to the inside in the short direction). In other words, the end portion 31Ab is formed on the surface of the first connecting portion 51 facing upward in Figure 4. The position of the end portion 31Aa of the first welded portion 31A, which is located on the inside of the hollow body 2, is at the boundary between the first wall portion 41 and the third wall portion 43, similar to Embodiment 1.

[0044] As in this embodiment, even if the end portion 31Ab of the first welded portion 31A (welded portion 3A) arranged on the outside of the hollow body 2 is formed on the surface of the first connecting portion 51, the first welded portion 31A is less conspicuous than, for example, the case where it is formed on the surface of the wall portion 4 (first wall portion 41), and is less likely to be mistaken for a cause of reduced strength or fracture of the aluminum alloy hollow extruded member 1A.

[0045] The welded portion 3A in this embodiment may be formed on all four connection portions 5 of the hollow body 2, or it may be formed on at least one connection portion 5.

[0046] <Embodiment 3> Embodiment 3 relates to an aluminum alloy hollow extruded member 1B, which is a modification of Embodiment 1. Figure 5 is a partial cross-sectional view of the aluminum alloy hollow extruded member 1B according to Embodiment 3, cut perpendicular to the longitudinal direction. The aluminum alloy hollow extruded member 1B of Embodiment 3 comprises a hollow body 2 with the same configuration as in Embodiment 1. In Figure 5, each component of the hollow body 2 is denoted by the same reference numerals as in Embodiment 1. In this embodiment, the formation position of the welded portion 3B is different from that of Embodiment 1. Here, we will explain using the case where the position in which the first welded portion 3B is formed on the first connecting portion 51 is changed as an example.

[0047] The first welded portion 31B extends diagonally across the first connecting portion 51 in a cross-sectional view of the aluminum alloy hollow extruded member 1B, inclined with respect to the thickness direction of the wall portion 4. However, the position of the end portion 31Bb of the welded portion 3B located on the outside of the hollow body 2 differs from that of Embodiment 1. Specifically, the end portion 31Bb is formed to be located on the end face of the first connecting portion 51, which is lower than the corner portion 51b of the first connecting portion 51. The position of the end portion 31Ba of the first welded portion 31B located on the inside of the hollow body 2 is the same as in Embodiment 1, at the boundary between the first wall portion 41 and the third wall portion 43.

[0048] As in this embodiment, even if the end portion 31Bb of the first welded portion 31B (welded portion 3B) located on the outside of the hollow body 2 is formed on the end face located to the side of the first connecting portion 51, the first welded portion 31B is less conspicuous than, for example, the case where it is formed on the surface of the wall portion 4 (third wall portion 43), and is less likely to be mistaken for a cause of reduced strength or fracture of the aluminum alloy hollow extruded member 1B.

[0049] In this embodiment, the welded portion 3B may be formed on all four connecting portions 5 of the hollow body 2, or it may be formed on at least one connecting portion 5.

[0050] <Embodiment 4> Embodiment 4 relates to an aluminum alloy hollow extruded member 1C, which is a modification of Embodiment 1. Figure 6 is a partial cross-sectional view of the aluminum alloy hollow extruded member 1C according to Embodiment 4, cut perpendicular to the longitudinal direction. The aluminum alloy hollow extruded member 1C of Embodiment 4 comprises a hollow body 2 with the same configuration as in Embodiment 1. In Figure 6, each component of the hollow body 2 is denoted by the same reference numerals as in Embodiment 1. In this embodiment, the formation position of the welded portion 3C is different from that of Embodiment 1. Here, we will explain using the case where the position in which the first welded portion 3C is formed on the first connecting portion 51 is changed as an example.

[0051] In a cross-sectional view of the aluminum alloy hollow extruded member 1C, the first welded portion 31C extends diagonally across the first connecting portion 51, inclined with respect to the thickness direction of the wall portion 4. However, the position of the end portion 31Ca of the welded portion 3C located inside the hollow body 2 differs from that of Embodiment 1. Specifically, the end portion 31Ca is formed on the inner wall surface 41a of the first wall portion 41, detached from the boundary between the first wall portion 41 and the fourth wall portion 43. The position of the end portion 31Cb of the first welded portion 31C located outside the hollow body 2 is the same as in Embodiment 1, at the corner portion 51b of the first connecting portion 51.

[0052] As in this embodiment, even if the end portion 31Ca of the first welded portion 31C (welded portion 3C) arranged inside the hollow body 2 is formed on the inner wall surface 41a of the first wall portion 41, the end portion 31Ca of the first welded portion 31C is difficult to see from the outside (i.e., it is not conspicuous).

[0053] In this embodiment, the welded portion 3C may be formed on all four connecting portions 5 of the hollow body 2, or it may be formed on at least one connecting portion 5.

[0054] <Embodiment 5> Embodiment 5 relates to an aluminum alloy hollow extruded member 1D, which is a modification of Embodiment 1. Figure 7 is a partial cross-sectional view of the aluminum alloy hollow extruded member 1D according to Embodiment 5, cut perpendicular to the longitudinal direction. The aluminum alloy hollow extruded member 1D of Embodiment 5 includes a hollow body 2 with the same configuration as in Embodiment 1. In Figure 7, each component of the hollow body 2 is denoted by the same reference numerals as in Embodiment 1. In this embodiment, the formation position of the welded portion 3D is different from that of Embodiment 1. Here, we will explain using the case where the position in which the first welded portion 3D is formed on the first connecting portion 51 is changed as an example.

[0055] The first welded portion 31D extends diagonally across the first connecting portion 51 and inclined with respect to the thickness direction of the wall portion 4 when viewed in cross-section of the aluminum alloy hollow extruded member 1D. However, the positions of the end portion 31Da of the welded portion 3D located inside the hollow body 2 and the end portion 31Db of the welded portion 3D located outside the hollow body 2 are different from those of Embodiment 1. Specifically, the end portion 31Da is formed on the inner wall surface 43a of the third wall portion 43, away from the boundary between the first wall portion 41 and the fourth wall portion 43. The end portion 31Db is formed away from the corner portion 51b of the first connecting portion 51 and is located closer to the first wall portion 41 (closer to the inside in the short direction). In other words, the end portion 31Db is formed on the surface of the first connecting portion 51 facing upward in Figure 7.

[0056] As in this embodiment, even if the end portion 31Da of the first welded portion 31D (welded portion 3D) located inside the hollow body 2 is formed on the inner wall surface 43a of the third wall portion 43, the end portion 31Da of the first welded portion 31D is difficult to see from the outside (i.e., not conspicuous), similar to Embodiment 4. Furthermore, even if the end portion 31Db of the first welded portion 31D (welded portion 3D) located outside the hollow body 2 is formed on the surface of the first connecting portion 51, it is not conspicuous, similar to Embodiment 2, and is unlikely to be mistaken for a cause of reduced strength or fracture of the aluminum alloy hollow extruded member 1D.

[0057] In this embodiment, the welded portion 3D may be formed on all four connecting portions 5 of the hollow body 2, or it may be formed on at least one connecting portion 5.

[0058] <Embodiment 6> Next, an aluminum alloy hollow extruded member 1F according to Embodiment 7 of the present invention will be described with reference to Figures 8 and 9. Figure 8 is a perspective view of an aluminum alloy hollow extruded member 1F according to Embodiment 6, and Figure 9 is a cross-sectional view taken along the β-β line in Figure 8. The aluminum alloy hollow extruded member 1F of this embodiment comprises a cylindrical body 21F that extends in a longitudinal direction L corresponding to the extrusion direction during extrusion molding by the port-hole extrusion method, and whose cross-section when cut perpendicular to the longitudinal direction L is rectangular, and a hollow body 2F having a plate-shaped partition wall portion (internal rib) 22F that partitions the space (hollow portion) 6F inside the cylindrical body 21F.

[0059] Of the hollow body 2F, the cylindrical body 21F has four wall sections 4F, each having a predetermined thickness and being plate-like, and each being arranged to form one side of a rectangular (an example of a polygonal) cross-section 2Fa, and four connecting sections 5F, each being arranged to form one corner of the rectangular cross-section 2Fa, and each connecting adjacent wall sections 4F to each other.

[0060] Furthermore, the aluminum alloy hollow extruded member 1F has four welded portions 3F, each extending along the longitudinal direction L, such that the cylindrical body 21F of the hollow body 2F is divided into four parts in the direction circumferential to the cross-section 2Fa, and one welded portion 30F, which extends along the longitudinal direction L, such that the partition wall portion 22F is divided into two parts in the vertical direction.

[0061] The welded portion 30F extends in the longitudinal direction L and does not appear on the outside of the aluminum alloy hollow extruded member 1F (cylindrical body 21F). The partition wall portion 22F is provided on the cylindrical body 21F so as to partition the space (hollow portion) 6 inside the four wall portions 4F. The partition wall portion 22F is plate-shaped and is positioned between the third wall portion 43F and the fourth wall portion 44F, parallel to them. Furthermore, the partition wall portion 22F is formed between the first wall portion 41F and the second wall portion 42F so as to be positioned perpendicular to the first wall portion 41F and the second wall portion 42F.

[0062] The four welded sections 3F are each inclined with respect to the thickness direction of the wall section 4F in the cross-section 2Fa of the hollow extruded aluminum alloy member 1F (the cylindrical body 21F of the hollow body 2F), and are allocated one at each connection section 5F so that they form a radial pattern overall.

[0063] The welded portion 30F is formed to divide the partition wall portion 22F into two parts: the first wall portion 41F side and the second wall portion 42F side. The position of the welded portion 30F is set to the center in the vertical direction. In other words, the welded portion 3F is set to divide the partition wall portion 22F into two equal parts in the vertical direction. This welded portion 30F is formed along the thickness direction of the plate-shaped partition wall portion 22F at the cross section 2Fa (end face) of the hollow body 2F. When the hollow body 2F includes the partition wall portion 22F, the welded portion 30F, together with four welded portions 3F, divides the entire hollow body 2F into four parts.

[0064] Furthermore, the position of the welded portion 30F in the partition wall portion 22F is not limited to the center, but may be set at any position in the vertical direction, as long as the objective of the present invention is not impaired, for example, as shown by the dashed line in the partition wall portion 22F in Figure 9.

[0065] Thus, in this embodiment as well, by positioning the ends of each welded portion 3F on the outside of the hollow body 2F at the corners of the corresponding connecting portions 5F, the welded portions 3F can be made less conspicuous when the aluminum alloy hollow extruded member 1F is viewed from the outside. Furthermore, as in this embodiment, the hollow body 2F may also include a partition wall portion 22F.

[0066] Furthermore, the formation position of each welded portion 3F in this embodiment may be changed as appropriate, as shown in the various modifications of Embodiment 1 described above, as long as the objective of the present invention is not impaired.

[0067] <Embodiment 7> Next, an aluminum alloy hollow extruded member 1G according to Embodiment 8 of the present invention will be described with reference to Figure 10. Figure 10 is a perspective view of the aluminum alloy hollow extruded member 1G according to Embodiment 8. The aluminum alloy hollow extruded member 1G of this embodiment is a so-called 3-port type, in which, during manufacturing, the billet (aluminum alloy billet) is divided into 3 sections along the extrusion direction by a plurality of port holes in a male mold.

[0068] The aluminum alloy hollow extruded member 1G has a hollow body 2G that extends in the longitudinal direction L corresponding to the extrusion direction during extrusion molding by porthole extrusion, and whose cross-section, when cut perpendicular to the longitudinal direction, is rectangular, and a plurality of welded parts 3G that extend along the longitudinal direction L, dividing the hollow body 2G into three parts in the direction circumferential to the cross-section. Inside the hollow body 2G there is a space (hollow part) 6G that extends in the longitudinal direction L.

[0069] The hollow body 2G has four wall sections 4G, each having a predetermined thickness and arranged to form each side of a rectangular cross-section, and four connecting sections 5G, each forming each corner of a rectangular cross-section and connecting adjacent wall sections 4G to each other.

[0070] Of the three welded sections 3G, at least two welded sections 3G (first welded section 31G, second welded section 32G) are inclined in cross-section with respect to the thickness direction of the wall section 4G, and one is assigned to each adjacent connection section 5G. Furthermore, of the three welded sections 3G, at least one welded section 3G (third welded section 33G) is assigned to the opposing wall section 42G (second wall section 42G) that faces the wall section 4G (first wall section 41G) which is located between adjacent connection sections 5G of the four wall sections 4G.

[0071] Of the four wall portions 4G, the first wall portion 41G, the third wall portion 43G, and the fourth wall portion 44 do not have welded portions 3G extending in the longitudinal direction L that are visible from the outside. However, as described above, the second wall portion 42G has a welded portion 3G (third welded portion 33G) extending in the longitudinal direction L. The welded portion 3 of the second wall portion 42G is formed so as to cross the second wall portion 42G in the thickness direction, as shown in Figure 10. The three welded portions 3G are arranged radially as a whole. Even in this embodiment, the welded portions 3G can be made inconspicuous. The formation positions of each welded portion 3G (first welded portion 31G, second welded portion 32G) formed on the connecting portion 5 may be changed as appropriate, as shown in the various modifications of Embodiment 1 described above, as long as the objective of the present invention is not impaired.

[0072] <Comparative Example 1> Next, the aluminum alloy hollow extruded member 1P according to Comparative Example 1 of the present invention will be described with reference to Figure 11. Figure 11 is a perspective view of the aluminum alloy hollow extruded member 1P according to Comparative Example 1. The aluminum alloy hollow extruded member 1P is manufactured by a port-hole extrusion method, similar to Embodiment 1, and comprises a hollow body 2P with a rectangular cross-section. The hollow body 2P is composed of four plate-shaped wall portions 4P and four connecting portions 5P, and has a space (hollow portion) 6P extending in the longitudinal direction L inside it.

[0073] Furthermore, in the aluminum alloy hollow extruded member 1P, one welded portion 3P is formed on each of the four wall portions 4P. When viewed in cross-section, the welded portions 3P are formed to follow the thickness direction of the wall portion 4P. In addition, the welded portions 3P are formed in a straight line along the longitudinal direction L.

[0074] In the aluminum alloy hollow extruded member 1P of Comparative Example 1, a welded portion 3P appears on the surface (outer wall surface) of the wall portion 4P, which may lead to the misconception that the welded portion 3P is the cause of reduced strength or fracture of the aluminum alloy hollow extruded member 1P.

[0075] Such misidentification can occur as long as the welded portion 3P is formed on the wall portion 4P, even if the formation position of the welded portion 3P is appropriately changed on the wall portion 4P. For example, even if the formation position of each welded portion 3P is changed to one of the multiple positions indicated by dashed lines on each wall portion 4P (first wall portion 41P, second wall portion 42P, third wall portion 43P, fourth wall portion 44P), these welded portions 3P are easily noticeable and can be easily seen from the outside of the aluminum alloy hollow extruded member 1P. Moreover, since all of these welded portions 3P are formed only on the wall portions 4P and not on the connecting portion 5P which connects the wall portions 4P perpendicularly to each other, they are easily mistaken for causing a decrease in strength or fracture of the aluminum alloy hollow extruded member 1P.

[0076] As long as the positions of the dashed lines on each wall section 4P are selected as the formation positions for each welded section 3P, it is easy to mistakenly believe that this will cause a decrease in strength or fracture of the hollow extruded aluminum alloy member 1P. Therefore, it is desirable to reduce the number of welded sections 3P selected from the wall sections 4P and the number of wall sections 4P on which the welded sections 3P are formed. As shown in the second wall section 42G of Figure 10, when selecting the formation position of a welded section 3P from any of the wall sections 4P, it is desirable to prioritize forming the welded section 3P on a wall section 4P that is less visible than other wall sections 4P. Here, a wall section 4P that is less visible may be a wall section 4P that is not exposed to the outside of the product to which the hollow extruded aluminum alloy member 1P is attached (for example, the mounting surface or adhesive surface to the product), a wall section 4P with a small surface area, or a wall section 4P that has not been anodized.

[0077] <Comparative Example 2> Next, the aluminum alloy hollow extruded member 1Q according to Comparative Example 2 of the present invention will be described with reference to Figure 12. Figure 12 is a perspective view of the aluminum alloy hollow extruded member 1Q according to Comparative Example 2. The aluminum alloy hollow extruded member 1Q of Comparative Example 2 is bent in such a way that its longitudinal direction L is curved compared to the aluminum alloy hollow extruded member 1P of Comparative Example 1.

[0078] In the aluminum alloy hollow extruded member 1Q of Comparative Example 2, as in Comparative Example 1, a welded portion 3Q appears on the surface (outer wall surface) of the wall portion 4Q. Therefore, it is possible that the welded portion 3Q may be mistakenly identified as the cause of strength reduction or fracture of the aluminum alloy hollow extruded member 1Q. Such a misidentification can occur regardless of the position of the neutral axis during bending or the peak position of residual stress.

[0079] Furthermore, such misidentification can occur as long as the welded portion 3Q is formed on the wall portion 4Q, even if the formation position of the welded portion 3Q is appropriately changed on the wall portion 4Q. For example, even if the formation position of each welded portion 3Q is changed to one of the multiple positions indicated by dashed lines on each wall portion 4Q (first wall portion 41Q, second wall portion 42Q, third wall portion 43Q, fourth wall portion 44Q), these welded portions 3Q are easily noticeable and can be easily seen from the outside of the aluminum alloy hollow extruded member 1Q. Moreover, since all of these welded portions 3Q are formed only on the wall portions 4Q and not on the connecting portion 5Q which connects the wall portions 4Q perpendicularly to each other, they are easily mistaken for causing a decrease in strength or fracture of the aluminum alloy hollow extruded member 1Q.

[0080] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention.

[0081] (1) The hollow extruded aluminum alloy member exemplified in Embodiment 1 above may be used for applications other than door beams.

[0082] (2) The material (aluminum alloy) used for the hollow extruded aluminum alloy member is not particularly limited as long as it can be manufactured by the port-hole extrusion method. Aluminum may also be used as the material.

[0083] (3) The hollow aluminum alloy extruded member exemplified in Embodiment 1 and the like may be processed as appropriate. For example, the hollow body of the hollow aluminum alloy extruded member may be bent so that its longitudinal direction is curved. [Explanation of Symbols]

[0084] 1...Aluminum alloy hollow extruded member, 2...Hollow body, 2a...Cross section, 3...Welded part, 4...Wall part, 5...Connecting part, 6...Hollow part, L...Longitudinal direction

Claims

1. An aluminum alloy hollow extruded member having a hollow body extending in a longitudinal direction corresponding to the extrusion direction during extrusion molding, and whose cross-section, when cut perpendicular to the longitudinal direction, includes a polygonal shape, and N welded portions, each extending along the longitudinal direction, such that the hollow body is divided into N portions (N is an integer of 2 or more) in a direction circumferential to the cross-section, The aforementioned hollow body is M wall sections (where M is an integer of 3 or more) are arranged so that each of them is in the shape of a plate having a predetermined thickness and each of them forms one of the sides of the cross-section, Each is arranged to form one of the corners of the cross-section, and each has M connecting parts that connect adjacent wall sections to each other. At least one of the welded portions is assigned to the connecting portion in the cross-section. The welded portions are each inclined with respect to the thickness direction of the wall portion, and one is assigned to each of the connecting portions, forming a radial pattern.

2. The aluminum alloy hollow extruded member according to Claim 1, wherein the welded portion extends inclined with respect to the thickness direction of the wall portion from the boundary portion of adjacent wall portions located inside the hollow body toward the corner portion of the connection portion located outside the hollow body at the assigned connection portion.

3. The end of the welded portion, which is located on the outside of the hollow body, is located at the corner of the connecting portion to which the welded portion is assigned, as described in Claim 1 or Claim 2.

4. The aluminum alloy hollow extruded member according to any one of claims 1 to 3, wherein the welded portion is formed to connect the boundary portion between adjacent wall portions located inside the hollow body and the corner portion of the connecting portion located outside the hollow body.

5. The hollow body has plate-shaped partition walls that divide the space inside the M wall portions, The aluminum alloy hollow extruded member according to any one of claims 1 to 3, having a single welded portion extending along the longitudinal direction so as to divide the partition wall portion into two in the vertical direction.

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