pipe

Abstract

A pipe capable of suppressing fluctuations in load that occur when it is axially crushed. [Solution] A pipe (10, 10A, 10B, 10C) includes a pipe body (11, 11C). The pipe body (11, 11C) includes beads (12, 12C) having a predetermined pitch (P) in the axial direction of the pipe body (11, 11C). The beads (12, 12C) have opposite ends (12a, 12b, 121a, 121b, 122a, 122b) in the circumferential direction of the pipe body (11, 11C) in a cross-sectional view of the pipe body (11, 11C). The beads (12, 12C) are formed on the pipe body (11, 11C) such that the positions of the beads (12, 12C) in the circumferential direction differ between cross-sectional surfaces of the pipe body (11, 11C) that are spaced apart in the axial direction.

Description

[Technical Field]

[0001] The present disclosure relates to pipes. [Background technology]

[0002] For example, a drop test apparatus as disclosed in Patent Document 1 is known as an apparatus for performing impact tests. The drop test apparatus of Patent Document 1 drops a test object, such as a portable product, onto a crash cradle. More specifically, the drop test apparatus of Patent Document 1 drops the test object while it is held by a test object holder, and before the test object hits the impact surface of the crash cradle, the test object holder releases the test object so that the test object falls alone. Patent Document 1 states that this shortens the time for the test object to fall alone and allows the test object to hit the impact surface in a set attitude and in a free fall state or a state close to that, thereby enabling a drop test with good reproducibility. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-055778 Summary of the Invention [Problem to be solved by the invention]

[0004] In the drop test device of Patent Document 1, the test object is caused to collide with the collision surface of the collision cradle. The collision with the collision surface causes an acceleration load on the test object. Depending on the test object or test standard, it may be desirable to suppress the acceleration applied to the test object, in other words, the fluctuation in the load generated on the test object and the collision cradle due to the collision. Even in tests other than impact tests, it may be desirable to suppress the fluctuation in the load generated on the test object or the member supporting the test object.

[0005] An object of the present disclosure is to provide a pipe that can suppress fluctuations in load that occur when axially crushed. [Means for solving the problem]

[0006] A pipe according to the present disclosure includes a pipe body. The pipe body includes beads arranged at a predetermined pitch in the axial direction of the pipe body. The beads have opposite ends in the circumferential direction of the pipe body when viewed in a cross section of the pipe body. The beads are formed on the pipe body such that the positions of the beads in the circumferential direction differ between cross sections of the pipe body spaced apart in the axial direction. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to suppress fluctuations in load that occur when a pipe is axially crushed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a pipe according to the first embodiment. [Figure 2] FIG. 2 is a side view of the pipe shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view (cross-sectional view taken along III-III) of the pipe shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view (IV-IV cross-sectional view) of the pipe shown in FIG. [Figure 5] FIG. 5 is a diagram showing an example of use of the pipe according to the first embodiment. [Figure 6A] FIG. 6A is a side view of a pipe according to the second embodiment. [Figure 6B] FIG. 6B is a side view of the pipe according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view (cross-sectional view taken along line VII-VII) of the pipe shown in FIG. 6A. [Figure 8] FIG. 8 is a cross-sectional view (VIII-VIII cross-sectional view) of the pipe shown in FIG. 6A. [Figure 9] FIG. 9 is a side view of a pipe according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view (cross-sectional view taken along line XX) of the pipe shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view (cross-sectional view taken along line XI-XI) of the pipe shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view (cross-sectional view taken along line XII-XII) of the pipe shown in FIG. [Figure 13] FIG. 13 is a perspective view of a pipe according to the fourth embodiment. [Figure 14] FIG. 14 is a side view of the pipe shown in FIG. [Figure 15] FIG. 15 is a cross-sectional view (cross-sectional view taken along line XV-XV) of the pipe shown in FIG. [Figure 16] FIG. 16 is a cross-sectional view (cross-sectional view taken along line XVI-XVI) of the pipe shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A pipe according to an embodiment includes a pipe body. The pipe body includes beads arranged at a predetermined pitch in the axial direction of the pipe body. The beads have opposite ends in the circumferential direction of the pipe body when viewed in a cross section of the pipe body. The beads are formed on the pipe body such that the positions of the beads in the circumferential direction differ between cross sections of the pipe body that are spaced apart in the axial direction (first configuration).

[0010] In the pipe according to the first configuration, beads are formed on the pipe body. The beads have a predetermined axial pitch and, in a cross-sectional view of the pipe body, have both ends in the circumferential direction of the pipe body. In addition, when comparing cross-sections of the pipe body spaced apart in the axial direction, the positions of the beads in the circumferential direction of the pipe body differ between the cross-sections. This reduces the fluctuation of the load generated in the pipe when the pipe is axially crushed. Specifically, the beads formed on the pipe body are subjected to an axial compressive load and can serve as the origin of deformation when the pipe is crushed. In the first configuration, the positions of the beads in the circumferential direction of the pipe body change along the axial direction of the pipe body. Therefore, when the pipe is crushed, the position of the deformation in the circumferential direction of the pipe body also changes along the axial direction of the pipe body. This uniformizes the deformation of the pipe, making it easier to generate uniform stress in the pipe. This reduces the fluctuation of the load generated when the pipe is axially crushed.

[0011] In the pipe according to the first configuration, the beads may include a plurality of first beads and a plurality of second beads. The plurality of first beads are arranged in the axial direction and extend in the circumferential direction. The plurality of second beads are arranged in the axial direction and extend in the circumferential direction. The plurality of second beads are arranged so as to be offset in position from the first beads in the axial and circumferential directions (second configuration).

[0012] In the pipe according to the first configuration, the beads may have a spiral shape (third configuration).

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In these drawings, the same or equivalent components are designated by the same reference numerals, and the same description will not be repeated.

[0014] First Embodiment [pipe] 1 is a perspective view of a pipe 10 according to this embodiment. The pipe 10 is used, for example, for impact testing of automobile parts, etc. The pipe 10 may also be used for tests other than impact testing.

[0015] Referring to Figure 1, a pipe 10 includes a pipe body 11. The pipe body 11 is tubular and has a central axis C. The pipe body 11 may also be tubular and based on a round tube. Hereinafter, the direction in which the central axis C extends will be referred to as the axial direction of the pipe body 11, and the circumferential and radial directions of a cylinder centered on the central axis C will be referred to as the circumferential and radial directions of the pipe body 11, respectively.

[0016] The pipe body 11 is formed with beads 12. In this embodiment, the beads 12 include a plurality of beads 121 and a plurality of beads 122.

[0017] The beads 121 are arranged in the axial direction of the pipe body 11. The beads 121 are preferably provided over substantially the entire axial direction of the pipe body 11. Of the multiple beads 121, the beads 121 arranged at both ends of the pipe body 11 in the axial direction may be arranged away from the pipe ends of the pipe body 11.

[0018] The beads 121 each extend in the circumferential direction of the pipe body 11. In the example of FIG. 1, the beads 121 have a concave shape on the inside of the pipe body 11. However, the beads 121 may also have a convex shape on the outside of the pipe body 11. Each of the beads 121 has, for example, a semicircular shape when viewed in a cross section perpendicular to its extension direction. However, each of the beads 121 may have a rectangular shape or the like when viewed in a cross section perpendicular to its extension direction. The shape of the beads 121 when viewed in a cross section perpendicular to its extension direction is not particularly limited.

[0019] The beads 122 are arranged in the axial direction of the pipe body 11. It is preferable that the beads 122 are provided over substantially the entire axial direction of the pipe body 11. Of the multiple beads 122, the beads 122 arranged at both ends of the pipe body 11 in the axial direction may be arranged away from the pipe ends of the pipe body 11. The beads 122 are arranged so as to be offset from the beads 121 in the axial and circumferential directions. The number of beads 122 arranged in the axial direction may be equal to the number of beads 121 arranged in the axial direction.

[0020] The beads 122 each extend in the circumferential direction of the pipe body 11. In the example of FIG. 1, the beads 122 have a concave shape on the inside of the pipe body 11. However, the beads 122 may also have a convex shape on the outside of the pipe body 11. Each of the beads 122 has, for example, a semicircular shape when viewed in a cross section perpendicular to its extension direction. However, each of the beads 122 may have a rectangular shape or the like when viewed in a cross section perpendicular to its extension direction. The shape of the beads 122 when viewed in a cross section perpendicular to its extension direction is not particularly limited.

[0021] FIG. 2 is a side view of the pipe 10. Referring to FIG. 2, the beads 12 are formed on the pipe body 11 at a predetermined pitch P in the axial direction of the pipe body 11. In this embodiment, a plurality of beads 121 are arranged in the axial direction at the pitch P. The bead 122 is arranged offset from the bead 121 by half the pitch P in the axial direction of the pipe body 11. The plurality of beads 122 are arranged in the axial direction at the pitch P at positions offset from the bead 121 in the circumferential direction of the pipe body 11. The pitch P of the beads 12 is preferably constant over the entire axial length of the pipe body 11, but may be variable.

[0022] When the length of each bead 121 in the axial direction of the pipe body 11 is width W1 and the length of each bead 122 in the axial direction of the pipe body 11 is width W2, the pitch P is larger than width W1 and width W2. The width W1 of the bead 121 may be equal to or different from the width W2 of the bead 122. When the maximum value of widths W1 and W2 is W, the pitch P may be (W+7) mm or more. The pitch P may also be less than (W+23) mm.

[0023] 3 and 4 are cross-sectional views of the pipe body 11. The cross-section of the pipe body 11 refers to a cross section of the pipe body 11 perpendicular to the central axis C.

[0024] 3 is a cross-sectional view (cross-sectional view taken along III-III in FIG. 2) of the pipe body 11 at the position of the bead 121. FIG. 3 shows the cross-section of the pipe body 11 when cut at the center of the bead 121 in width.

[0025] In the cross-sectional view shown in FIG. 3, the bead 121 has both end portions 121a and 121b in the circumferential direction of the pipe body 11. That is, the bead 121 does not extend over the entire circumference of the pipe body 11. In the cross-section of the pipe body 11, there is a portion where the bead 121 is not provided, that is, a break in the bead 121.

[0026] In the cross-section shown in FIG. 3, when the length of the bead 121 in the circumferential direction of the pipe body 11 is L1 and the circumferential length of the pipe body 11 is L0, L0 and L1 may satisfy 0.35 < L1 / L0 < 0.95. The circumferential length L0 can be obtained by multiplying the diameter of the pipe body 11 by π. Although not particularly limited, the circumferential length L0 may be 60 mm or more. The circumferential length L0 may be 160 mm or less.

[0027] The bead 121 has a depth D1 in the radial direction of the pipe body 11. Depending on the diameter of the pipe body 11, the depth D1 of the bead 121 is, for example, 1.5 mm or more. The depth D1 of the bead 121 may be, for example, 4.5 mm or less.

[0028] FIG. 4 is a cross-sectional view of the pipe body 11 at a position axially separated from the cross-section shown in FIG. 3 by 1 / 2 of the pitch P (cross-section IV-IV in FIG. 2). FIG. 4 is a cross-sectional view of the pipe body 11 at the position of the bead 122. More specifically, FIG. 4 shows a cross-section of the pipe body 11 when cut at the center of the width of the bead 122.

[0029] The bead 12 (FIGS. 1 and 2) is formed on the pipe body 11 so that its circumferential position is shifted between cross-sections of the pipe body 11 separated axially. In the present embodiment, the circumferential position of the pipe body 11 is different between the bead 121 included in the cross-section shown in FIG. 3 and the bead 122 included in the cross-section shown in FIG. 4. In the example of the present embodiment, the bead 122 is arranged at a position shifted 180° around the central axis C from the bead 121.

[0030] In the cross-sectional view shown in FIG. 4, the bead 122 has both end portions 122a and 122b in the circumferential direction of the pipe body 11. That is, the bead 122 does not extend over the entire circumference of the pipe body 11. In the cross-section of the pipe body 11, there is a portion where the bead 122 is not provided, that is, a break in the bead 122.

[0031] In the cross-section shown in FIG. 4, when the length of the bead 122 in the circumferential direction of the pipe body 11 is L2, L0 and L2 may satisfy 0.35 < L2 / L0 < 0.95. In the present embodiment, L2 / L0 is equal to L1 / L0 (FIG. 3). However, L2 / L0 may be different from L1 / L0.

[0032] The bead 122 has a depth D2 in the radial direction of the pipe body 11. Depending on the diameter of the pipe body 11, the depth D2 of the bead 122 is, for example, 1.5 mm or more. The depth D2 of the bead 122 may be, for example, 4.5 mm or less. The depth D2 of the bead 122 is preferably equal to the depth D1 of the other bead 121 (FIG. 3), but may be different from the depth D1 of the bead 121.

[0033] The pipe body 11 is typically made of metal. The pipe body 11 may be made of steel. The pipe body 11 including the concave or convex beads 121 and 122 can be manufactured, for example, by joining semi-circular pipe-shaped parts having the beads 121 and 122 formed thereon by laser welding or the like. In this case, the semi-circular pipe-shaped parts having the beads 121 and 122 formed thereon can be formed, for example, by pressing a metal plate. Alternatively, concave or convex beads 121 and 122 may be formed on the pipe body 11 by hot blow molding or the like.

[0034] [Test Equipment] The pipe 10 according to this embodiment can be used, for example, in an impact test. FIG. 5 is a schematic diagram showing a test facility 20 for performing an impact test. As shown in FIG. 5, the test facility 20 includes a receiving body 21 and a holding body 22. The holding body 22 has, for example, a frame shape and can hold a test body 30. The test body 30 may be an automobile part such as a battery case.

[0035] The holder 22 is disposed above the receiver 21. The pipe 10 according to this embodiment is installed in the receiver 21. More specifically, at least one pipe 10 is disposed between an upper plate 211 and a lower plate 212 in the receiver 21. The pipe 10 is installed in the receiver 21 so that its axial direction substantially coincides with the up-down direction. A shaft member 213 may be disposed within the pipe 10. The upper end of the shaft member 213 is fixed to the upper plate 211, for example, by a bolt. The lower end of the shaft member 213 does not have to be fixed to the lower plate 212. For example, a through-hole through which the shaft member 213 can be inserted may be formed in the lower plate 212. The shaft member 213 moves axially within this through-hole, thereby allowing the upper plate 211 to which the shaft member 213 is fixed to descend.

[0036] When performing an impact test on the test specimen 30 using the test facility 20, the holder 22 holding the test specimen 30 is placed at a predetermined height above the receiving body 21. The holder 22 is then dropped and caused to collide with the receiving body 21. This causes the pipe 10 installed on the receiving body 21 to crush in the axial direction, and acceleration is applied to the test specimen 30 held by the holder 22. In the impact test, it is evaluated whether or not this acceleration causes destruction or damage to the internal structure or contents of the test specimen 30. If the test specimen 30 is an automobile battery case, for example, destruction or damage to the end of a cross member, bolt fastening parts, etc. within the test specimen 30 may be evaluated.

[0037] [effect] In the pipe 10 according to this embodiment, beads 12 are formed on the pipe body 11. The beads 12 include a plurality of beads 121 and 122 extending in the circumferential direction of the pipe body 11. The beads 121 are arranged in the axial direction at a predetermined pitch P. Similarly, the beads 122 are arranged in the axial direction at a predetermined pitch P. However, the beads 122 are arranged in the pipe body 11 so as to be offset from the beads 121 in the axial and circumferential directions. Therefore, when comparing cross sections of the pipe body 11 spaced apart in the axial direction, the positions of the beads 121 and 122 in the circumferential direction of the pipe body 11 differ. For example, when comparing cross sections of pipe bodies 11 spaced apart in the axial direction within a range of one pitch P, the positions of the beads 121 and 122 in the circumferential direction differ between the cross sections. Furthermore, in a cross-sectional view of the pipe body 11, each of the beads 121 has opposite circumferential ends 121a, 121b, and each of the beads 122 has opposite circumferential ends 122a, 122b. This makes it possible to suppress fluctuations in the load generated in the pipe 10 when the pipe 10 is axially crushed. Specifically, the beads 121, 122 formed on the pipe body 11 are subjected to an axial compressive load, and serve as the starting points for deformation when the pipe 10 is crushed. When the pipe 10 is axially crushed, deformation of the pipe body 11 occurs at each of the beads 121, 122, making it easy for uniform deformation to occur in the pipe 10 in both the axial and circumferential directions, and making the stress generated in the pipe 10 uniform. This makes it easy to suppress fluctuations in the load generated when the pipe 10 is axially crushed.

[0038] By providing the beads 121, 121 on the pipe body 11, it becomes easier to reduce the fluctuation of the load generated when the pipe 10 is axially crushed. For example, when the pipe 10 is crushed in the axial direction, the fluctuation of the load generated in a stroke (displacement) of 5% to 65% of the axial length of the pipe body 11 is 25% or less. The fluctuation of the load generated is defined as the average F of the maximum and minimum values ​​of the load generated in the stroke range of 5% to 65% of the axial length of the pipe body 11. Ave The fluctuation of the generated load is 25% or less when the generated load is F within the above stroke range. Ave×0.875 or more, F Ave × 1.125 or less.

[0039] Second Embodiment 6A and 6B are side views of a pipe 10A according to this embodiment. The pipe 10A differs from the pipe 10 according to the first embodiment in the number of beads 121, 122 provided on the pipe body 11.

[0040] In the pipe 10 according to the first embodiment, one row of beads 121 and one row of beads 122 are formed on the pipe body 11. On the other hand, in the pipe 10A according to the present embodiment, multiple rows of beads 121 and multiple rows of beads 122 are formed on the pipe body 11. As shown in FIGS. 6A and 6B, two rows of beads 121 and two rows of beads 122 are formed on the pipe body 11. However, three or more rows of beads 121 and three or more rows of beads 122 may be formed on the pipe body 11. Each row of beads 122 is positioned offset from each row of beads 121 in the axial and circumferential directions of the pipe body 11. Each row of beads 122 is positioned offset from each row of beads 121 by ½ of the pitch P in the axial direction of the pipe body 11. In the example of FIGS. 6A and 6B, each row of beads 122 is positioned offset by 90° around the central axis C from the beads 121. The pitch P of the beads 121, 122 may be set in the same manner as in the first embodiment.

[0041] FIG. 7 is a cross-sectional view of the pipe body 11 at the position of the bead 121 (cross-sectional view taken along line VII-VII in FIG. 6A). Like FIG. 3, FIG. 7 shows a cross-sectional view of the pipe body 11 when cut at the center of the width of the bead 121. FIG. 8 is a cross-sectional view of the pipe body 11 at the position of the bead 122. FIG. 8 is a cross-sectional view of the pipe body 11 at a position axially separated by 1 / 2 the pitch P from the cross-sectional view shown in FIG. 7 (cross-sectional view taken along line VIII-VIII in FIG. 6A). FIG. 8 shows a cross-sectional view of the pipe body 11 at the position of the bead 122. Like FIG. 4, FIG. 8 shows a cross-sectional view of the pipe body 11 when cut at the center of the width of the bead 122.

[0042] The cross-section of the pipe body 11 shown in FIG. 7 includes a plurality of beads 121. The cross-section can include, for example, 2 or more and 8 or less beads 121. In the cross-section of the pipe body 11 shown in FIG. 7, the plurality of beads 121 are arranged at intervals in the circumferential direction of the pipe body 11. Therefore, each of the beads 121 has both end portions 121a and 121b in the circumferential direction in the cross-sectional view of the pipe body 11. In the example of FIG. 7, the cross-section of the pipe body 11 includes two beads 121.

[0043] When the cross-section of the pipe body 11 includes a plurality of beads 121, the sum of the lengths of the plurality of beads 121 is the length L1 of the bead 121. In the example of FIG. 7, each of the beads 121 may have a length of L1 / 2 in the circumferential direction of the pipe body 11. The length L1 of the bead 121 in the circumferential direction of the pipe body 11 and the circumferential length L0 of the pipe body 11 may satisfy 0.35 < L1 / L0 < 0.95, similar to the first embodiment.

[0044] The cross-section of the pipe body 11 shown in FIG. 8 includes a plurality of beads 122. The cross-section includes, for example, 2 or more and 8 or less beads 122. In the cross-section of the pipe body 11 shown in FIG. 8, the plurality of beads 122 are arranged at intervals in the circumferential direction of the pipe body 11. Therefore, each of the beads 122 has both end portions 122a and 122b in the circumferential direction in the cross-sectional view of the pipe body 11. In the example of FIG. 8, the cross-section of the pipe body 11 includes two beads 122.

[0045] When the cross-section of the pipe body 11 includes a plurality of beads 122, the sum of the lengths of the plurality of beads 122 is the length L2 of the bead 122. In the example of FIG. 8, each of the beads 122 may have a length of L2 / 2 in the circumferential direction of the pipe body 11. The length L2 of the bead 122 in the circumferential direction of the pipe body 11 and the circumferential length L0 of the pipe body 11 may satisfy 0.35 < L2 / L0 < 0.95, similar to the first embodiment. L2 / L0 may be equal to L1 / L0 (FIG. 7) or different.

[0046] In the pipe 10A according to this embodiment, when cross sections (FIGS. 7 and 8) of the pipe body 11 spaced apart in the axial direction are compared, the positions of the beads 121 and 122 in the circumferential direction of the pipe body 11 differ between the cross sections. Therefore, the pipe 10A can achieve the same effect as the pipe 10 according to the first embodiment. That is, similar to the first embodiment, the fluctuation in load that occurs when the pipe 10A is axially crushed is easily suppressed.

[0047] Third Embodiment 9 is a side view of a pipe 10B according to this embodiment. The pipe 10B differs from the pipe 10 according to the first embodiment in that the bead 12 further includes a plurality of beads 123.

[0048] 9, the beads 123 are arranged in the axial direction of the pipe body 11. The beads 123 are preferably provided over substantially the entire axial length of the pipe body 11. Of the multiple beads 123, the beads 123 arranged at both ends of the pipe body 11 in the axial direction may be arranged away from the pipe ends of the pipe body 11. The beads 123 are arranged so as to be offset from the beads 121 and 122 in the axial and circumferential directions.

[0049] In this embodiment, the bead 122 is arranged offset from the bead 121 in the axial direction of the pipe body 11. The bead 123 is arranged offset from the bead 122 in the axial direction of the pipe body 11. The beads 123 are arranged in the axial direction at a pitch P at positions offset from the beads 121 and 122 in the circumferential direction of the pipe body 11. The number of beads 123 arranged in the axial direction may be equal to the number of beads 121 arranged in the axial direction and the number of beads 122 arranged in the axial direction.

[0050] When the length of each bead 123 in the axial direction of the pipe body 11 is defined as width W3, the width W3 of the bead 123 may be equal to or different from the widths W1 and W2 of the beads 121 and 122. The pitch P of the beads 121, 122, and 123 may be set in the same manner as in the first embodiment, with W being the maximum value of the widths W1, W2, and W3.

[0051] The beads 123 each extend in the circumferential direction of the pipe body 11. In the example of FIG. 1, the beads 123 have a concave shape on the inside of the pipe body 11. However, the beads 123 may also have a convex shape on the outside of the pipe body 11. Each of the beads 123 has, for example, a semicircular shape when viewed in a cross section perpendicular to its extension direction. However, each of the beads 123 may have a rectangular shape or the like when viewed in a cross section perpendicular to its extension direction. The shape of the beads 123 when viewed in a cross section perpendicular to its extension direction is not particularly limited.

[0052] FIG. 10 is a cross-sectional view of the pipe body 11 at the position of the bead 121 (cross-sectional view taken along line XX in FIG. 9). Like FIG. 3, FIG. 10 shows a cross-sectional view of the pipe body 11 taken at the center of the width of the bead 121. FIG. 11 is a cross-sectional view of the pipe body 11 at the position of the bead 122. FIG. 11 is a cross-sectional view of the pipe body 11 taken at a position axially spaced by 1 / 3 of the pitch P from the cross-sectional view shown in FIG. 10 (cross-sectional view taken along line XI-XI in FIG. 9). FIG. 11 shows a cross-sectional view of the pipe body 11 at the position of the bead 122. Like FIG. 4, FIG. 11 shows a cross-sectional view of the pipe body 11 taken at the center of the width of the bead 122. FIG. 12 is a cross-sectional view of the pipe body 11 taken at the position of the bead 123. FIG. 12 is a cross-sectional view of the pipe body 11 taken at a position axially spaced by 1 / 3 of the pitch P from the cross-sectional view shown in FIG. 11 (cross-sectional view taken along line XII-XII in FIG. 9). 12 shows a cross section of the pipe body 11 at the position of the bead 123. FIG. 12 shows a cross section of the pipe body 11 when cut at the center of the bead 123 across its width.

[0053] Similar to other embodiments, when comparing cross-sections of the axially spaced pipe body 11, the beads 121, 122, 123 are arranged offset from each other in the circumferential direction. Specifically, referring to FIGS. 10 and 11, when comparing cross-sections of the pipe body 11 axially separated by 1 / 3 of the pitch P, the bead 122 is arranged offset from the bead 121 in the circumferential direction. Referring to FIGS. 11 and 12, when comparing cross-sections of the pipe body 11 axially separated by 1 / 3 of the pitch P, the bead 123 is arranged offset from the bead 122 in the circumferential direction. In the present embodiment, the beads 121, 122, 123 are arranged offset from each other by 120° around the central axis C.

[0054] In the cross-section shown in FIG. 12, the bead 123 has both end portions 123a, 123b in the circumferential direction of the pipe body 11. That is, the bead 123 does not extend over the entire circumference of the pipe body 11. In the cross-section of the pipe body 11, there is a portion where the bead 123 is not provided, that is, a break in the bead 123.

[0055] In the cross-section shown in FIG. 12, when the length of the bead 123 in the circumferential direction of the pipe body 11 is L3, L3 may satisfy 0.35 < L3 / L0 < 0.95, similar to L1, L2 (FIGS. 10 and 11). L3 / L0 may be equal to L1 / L0 and L2 / L0, or may be different. In the present embodiment, since the cross-section of the pipe body 11 includes a single bead 123, the length of the bead 123 in the circumferential direction of the pipe body 11 is L3. On the other hand, when the cross-section of the pipe body 11 includes a plurality of beads 123, the sum of the lengths of the plurality of beads 123 is L3.

[0056] The bead 123 has a depth D3 in the radial direction of the pipe body 11. Depending on the diameter of the pipe body 11, the depth D3 of the bead 123 is, for example, 1.5 mm or more. The depth D3 of the bead 123 may be, for example, 4.5 mm or less. The depth D3 of the bead 123 is preferably equal to the depths D1, D2 of the other beads 121, 122 (FIGS. 10 and 11), but may be different from the depths D1, D2.

[0057] In the pipe 10B according to this embodiment, when cross sections (FIGS. 10 to 12) of the pipe body 11 spaced apart in the axial direction are compared, the positions of the beads 121, 122, 123 in the circumferential direction of the pipe body 11 differ between the cross sections. Therefore, the pipe 10B can achieve the same effect as the pipe 10 according to the first embodiment. That is, similar to the first embodiment, fluctuations in the load that occur when the pipe 10B is axially crushed are easily suppressed.

[0058] In this embodiment, the pipe body 11 includes a row of beads 123 that is disposed offset in the axial and circumferential directions from the row of beads 121 and the row of beads 122. In the pipe body 11, there is one row of beads 121, one row of beads 122, and one row of beads 123. However, similar to the second embodiment, a plurality of rows of beads 121, a plurality of rows of beads 122, and a plurality of rows of beads 123 may be formed in the pipe body 11. In this case, a cross section of the pipe 10B will include a plurality of any of the beads 121, the beads 122, and the beads 123.

[0059] When the bead 12 includes multiple bead rows as in the first to third embodiments, the positions of the beads 12 in the circumferential direction of the pipe body 11 differ between cross sections of the pipe body 11 that are spaced apart in the axial direction by a pitch of P×1 / N. N is the number of bead rows that differ in axial position. For example, in the first and second embodiments, the bead 12 includes two types of bead rows that differ in axial position, i.e., a row of beads 121 and a row of beads 122. In the first and second embodiments, N=2, and each cross section of the pipe body 11 that is spaced apart in the axial direction by a pitch of P×1 / 2 includes at least one bead 121 or at least one bead 122. When a cross section of the pipe body 11 that includes a bead 121 is compared with a cross section of the pipe body 11 that includes a bead 122, the positions of the beads 121 and 122 are shifted in the circumferential direction. Also, for example, in the third embodiment, the beads 12 include three types of bead rows that differ in axial position, namely, a row of beads 121, a row of beads 122, and a row of beads 123. In the third embodiment, N=3, and cross sections of the pipe body 11 spaced axially apart by a pitch P×1 / 3 include at least one bead 121, at least one bead 122, or at least one bead 123. When comparing the cross section of the pipe body 11 including the bead 121, the cross section of the pipe body 11 including the bead 122, and the cross section of the pipe body 11 including the bead 123, the positions of the beads 121, 122, and 123 are shifted in the circumferential direction.

[0060] <Fourth embodiment> Fig. 13 is a perspective view of a pipe 10C according to this embodiment. Fig. 14 is a side view of the pipe 10C. The pipe 10C differs from the pipe 10 according to the first embodiment in the configuration of the beads 12C.

[0061] 13 and 14, the beads 12C have a spiral shape. The beads 12C are formed on the pipe body 11C so as to have a predetermined pitch P in the axial direction. The beads 12C may be provided over substantially the entire axial length of the pipe body 11C. The spiral beads 12C may or may not reach the end of the pipe body 11C. The pitch P of the beads 12C may be (W+11) mm or more, where W is the distance between the side edges of the beads 12C. The pitch P of the beads 12C may be less than (W+17) mm. In this embodiment, the pitch P of the beads 12C is preferably constant over the entire axial length of the pipe body 11C, but may be variable.

[0062] In this embodiment, the bead 12C has a concave shape on the inside of the pipe body 11C. However, the bead 12C may have a convex shape on the outside of the pipe body 11C. The bead 12C has, for example, a semicircular shape when viewed in a cross section perpendicular to its extension direction. However, the bead 12C may have a rectangular shape or the like when viewed in a cross section perpendicular to its extension direction. The shape of the bead 12C when viewed in a cross section perpendicular to its extension direction is not particularly limited.

[0063] Fig. 15 is a cross-sectional view of the pipe body 11C (cross-sectional view taken along XV-XV in Fig. 14). Fig. 16 is a cross-sectional view of the pipe body 11C at a position axially separated by half the pitch P from the cross-section shown in Fig. 15 (cross-sectional view taken along XVI-XVI in Fig. 14). Figs. 15 and 16 show cross-sections of the pipe body 11C when cut at the center of the width of the bead 12C.

[0064] As shown in Figures 15 and 16, when the bead 12C is spiral, the position of the bead 12C in the circumferential direction of the pipe body 11C differs between cross sections of the pipe body 11C that are axially separated by half the pitch P in the axial direction. That is, the bead 12C in the cross section shown in Figure 16 is shifted in the circumferential direction of the pipe body 11C relative to the bead 12C in the cross section shown in Figure 15. In addition, in each cross section shown in Figures 15 and 16, the bead 12C has both end portions 12a and 12b in the circumferential direction of the pipe body 11C. That is, there are portions in the cross section of the pipe body 11C where the bead 12C is not provided, i.e., gaps in the bead 12C.

[0065] The bead 12C has a depth D in the radial direction of the pipe body 11C. Although it depends on the diameter of the pipe body 11C, the depth D of the bead 12C is, for example, 2 mm or more. The depth D of the bead 12C may be, for example, 3 mm or less.

[0066] In the pipe 10C according to this embodiment, when cross sections (FIGS. 15 and 16) of the pipe main body 11C spaced apart in the axial direction are compared, the positions of the beads 12C in the circumferential direction of the pipe main body 11C are different between the cross sections. Therefore, the pipe 10C can achieve the same effects as the pipes 10, 10A, and 10B according to the other embodiments. That is, as with the other embodiments, the fluctuations in load that occur when the pipe 10C is axially crushed are easily suppressed.

[0067] The pipe 10C according to this embodiment can be manufactured in the same manner as the pipe 10 according to the first embodiment. The pipes 10A and 10B according to the other embodiments can also be manufactured in the same manner as the pipe 10 according to the first embodiment.

[0068] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0069] In the pipes 10, 10A according to the first and second embodiments, each of the beads 121, 122 extends parallel to the circumferential direction of the pipe body 11. In the pipe 10B according to the third embodiment, each of the beads 121, 122, 123 extends in the circumferential direction of the pipe body 11. However, the beads 121, 122, 123 do not necessarily have to extend parallel to the circumferential direction of the pipe body 11. The beads 121, 122, 123 may be inclined with respect to the circumferential direction of the pipe body 11.

[0070] In the first embodiment, an example in which the pipe 10 is used for an impact test has been described. However, the use of the pipe 10 is not limited to this. For example, by using the pipe 10, which generates a small load as a fulcrum for a three-point bending test, it is possible to perform the three-point bending test while applying a longitudinal tensile load to the test specimen. The pipe 10 can be used for various mechanical tests. The pipes 10A, 10B, and 10C according to other embodiments may also be used for impact tests, or for mechanical tests other than impact tests. [Example]

[0071] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0072] To confirm the effects of this disclosure, CAE analysis of axial crushing of various pipes was performed using commercially available analysis software (LS-DYNA, manufactured by Ansys). In this analysis, a constant compressive load was applied to the pipe in the axial direction, and the variation in the generated load was evaluated within a stroke range of 5% to 65% of the axial length of the pipe body. The analysis conditions and results are shown in Table 1.

[0073] [Table 1]

[0074] Referring to Table 1, Examples 1 to 5 and 9 to 12 are pipes in which a plurality of circumferentially extending beads are provided on the pipe body, similar to the pipes 10, 10A, and 10B according to the first to third embodiments. In Examples 1 to 5 and 9 to 12, the beads were formed on the pipe body so that, in a cross-sectional view of the pipe body, the beads have both ends in the circumferential direction of the pipe body, and the circumferential position of the beads differs between cross sections of the pipe body that are separated in the axial direction. In Examples 6 to 8 and 13 to 16, a spiral bead was formed on the pipe body, similar to the pipe 10C according to the fourth embodiment. In Examples 6 to 8 and 13 to 16, the beads also have both ends in the circumferential direction of the pipe body in a cross-sectional view of the pipe body, and the circumferential position of the beads differs between cross sections of the pipe body that are separated in the axial direction. The comparative example was a round pipe without a bead.

[0075] In Table 1, "diameter" and "plate thickness" are the maximum diameter and plate thickness of the pipe body, and "length" is the axial length of the pipe body (pipe length). "Steel type" is the tensile strength of the steel that is the material of the pipe body. The "bead" column shows the shape, depth, and pitch of the beads provided on the pipe body.

[0076] As shown in Table 1, when a constant compressive load was applied to the pipe in the axial direction to cause it to be axially crushed, the fluctuation in the load generated in the comparative example was 60% within a stroke range of 5% to 65% of the pipe length. In contrast, in Examples 1 to 16, when a constant compressive load was applied to the pipe in the axial direction to cause it to be axially crushed, the fluctuation in the load generated in the pipe was reduced compared to the comparative example. In each example, the fluctuation in the generated load was 25% or less within a stroke range of 5% to 65% of the axial length of the pipe body.

[0077] This analysis confirmed that by forming beads on the pipe body so that they have both ends in the circumferential direction of the pipe body when viewed in cross section, and so that the position of the beads in the circumferential direction differs between cross sections of the pipe body that are spaced apart in the axial direction, the fluctuations in load that occur when the pipe is axially crushed can be suppressed. [Explanation of symbols]

[0078] 10, 10A, 10B, 10C: Pipe 11, 11C: Pipe body 12,12C:Bead 121: Bead (first bead) 122: Bead (second bead) 12a, 12b, 121a, 121b, 122a, 122b: End P: Pitch

Claims

1. a pipe body including beads having a predetermined pitch in the axial direction; A pipe in which the bead has both ends in the circumferential direction of the pipe body when viewed in a cross-section of the pipe body, and is formed on the pipe body so that the position of the bead in the circumferential direction differs between cross-sections of the pipe body that are separated in the axial direction.

2. 2. The pipe of claim 1, The bead is a plurality of first beads arranged in the axial direction and each extending in the circumferential direction; a plurality of second beads arranged in the axial direction, each extending in the circumferential direction, and shifted in position relative to the first bead in the axial direction and the circumferential direction; Including pipes.

3. 2. The pipe of claim 1, The bead has a spiral shape.

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