Member bonding structure

Abstract

This invention provides a joint structure for members that improves the pull-out strength between members. [Solution] This disclosure provides a joint structure for a member comprising a first member 10 having a hollow circular cross-section and a second member 20 having a hollow circular cross-section, wherein the end 12 of the first member 10 is inserted inside the end 22 of the second member 20, a recess is formed in the end 12 of the first member 10 that is recessed radially inward, and a convex portion is formed in the end 22 of the second member 20 that protrudes radially inward, and the convex portion formed in the end 22 of the second member 20 is fitted into the recess formed in the end 12 of the first member 10.

Description

Technical Field

[0005] , , ,

[0001] This disclosure relates to a coupling structure of members.

Background Art

[0002] Patent Document 1 discloses a shaft component in which a press-fitting portion protruding from a first shaft forming member is press-fitted into a press-fitting portion recessed in a second shaft forming member to be integrated. The press-fitting portion has a stepped portion having a function as a guide margin and a function as a press-fitting margin, thereby suppressing a decrease in pull-out strength.

Prior Art Documents

Patent Documents

[0003] [[ID=2 3]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, if the first shaft forming member or the second shaft forming member is pulled out with a force greater than the frictional force acting between the outer peripheral surface of the press-fitting portion and the inner peripheral surface of the press-fitting portion, the two members will be easily disassembled. This disclosure solves such problems and provides a coupling structure of members with improved pull-out strength between members.

Means for Solving the Problems

[0005] This disclosure is a coupling structure of members in which a first member having a hollow circular cross-section and a second member having a hollow circular cross-section are coupled. An end portion of the first member is inserted inside an end portion of the second member. A recess recessed radially inward is formed in the end portion of the first member, and a protrusion protruding radially inward is formed in the end portion of the second member. The protrusion formed in the end portion of the second member is fitted into the recess formed in the end portion of the first member. This structure improves the pull-out strength between components.

[0006] The end of the first member is reduced in diameter relative to the central part of the first member, and the outer diameter of the central part of the first member and the outer diameter of the central part of the second member are formed to be substantially the same. With this structure, there is no gap in the radial direction between the first member and the second member, and the space can be used effectively. [Effects of the Invention]

[0007] This disclosure provides a joint structure for members that improves the pull-out strength between members. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of the first and second members before joining, showing the joining structure of the members according to Embodiment 1. [Figure 2] This is a cross-sectional view showing the joining structure of the members according to Embodiment 1, in which the end of the first member is inserted inside the end of the second member. [Figure 3] This is a cross-sectional view showing the bonding structure of the member according to Embodiment 1. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described below with reference to Figures 1 to 3. Figure 1 is a cross-sectional view of the first member and the second member before joining, showing the joining structure of the members of Embodiment 1. Figure 2 is a cross-sectional view showing the state in which the end of the first member is inserted inside the end of the second member, showing the joining structure of the members of Embodiment 1. Figure 3 is a cross-sectional view showing the joining structure of the members of Embodiment 1.

[0010] Embodiment 1 The member joining structure 30 according to Embodiment 1 is composed of a first member 10 and a second member 20. The first member 10 and the second member 20 before joining will be explained with reference to Figure 1.

[0011] The first member 10 is a steel pipe formed from a steel plate into a cylindrical shape using a roll. The first member 10 has a hollow circular cross-section. The first member 10 has a central portion 11 and an end portion 12. The central portion 11 is formed in the central part of the first member 10 in the axial direction (the X-axis direction shown in Figure 1) (the left side of the dashed line A1 shown in Figure 1). The central portion 11 has the same inner and outer diameter in the axial direction.

[0012] The end portion 12 is formed at the axial end of the first member 10 (the right-hand portion of the dashed line A1 shown in Figure 1). The end portion 12 has a first end portion 13 and a second end portion 14. The first end portion 13 is formed on the central portion 11 side of the end portion 12 (to the left of the dashed line A2 shown in Figure 1 and to the right of the dashed line A1), and the second end portion 14 is formed on the tip side of the end portion 12 (to the right of the dashed line A2 shown in Figure 1).

[0013] The second end 14 side of the first end 13 is formed with the same inner and outer diameters in the axial direction. The central part 11 side of the first end 13 gradually increases in both inner and outer diameters as it moves from the second end 14 side towards the central part 11 side.

[0014] The second end portion 14 has a terminal portion 14a and an inclined portion 14b. The terminal portion 14a is formed on the tip side of the second end portion 14, and the inclined portion 14b is formed on the first end portion 13 side of the second end portion 14. The terminal portion 14a has the same inner and outer diameter in the axial direction. The inclined portion 14b gradually increases in both inner and outer diameter as it moves from the terminal portion 14a side toward the first end portion 13 side.

[0015] The outer diameters of the first end 13 and the second end 14 are smaller than the outer diameter of the central part 11. The inner diameters of the first end 13 and the second end 14 are smaller than the inner diameter of the central part 11.

[0016] The outer diameter of the second end 14 is smaller than the outer diameter of the first end 13. The inner diameter of the second end 14 is smaller than the inner diameter of the first end 13.

[0017] The diameter reduction of the end portion 12 with respect to the central portion 11 is achieved by drawing. Also, the diameter reduction of the second end portion 14 with respect to the first end portion 13 is also achieved by drawing. Note that the diameter reduction of these pipes may be processed by other methods instead of drawing.

[0018] The second member 20 is a steel pipe formed by rolling a steel plate into a cylindrical shape. The second member 20 has a hollow circular cross-section. The second member 20 has a central portion 21 and an end portion 22. The central portion 21 is formed at the central portion in the axial direction (X-axis direction shown in FIG. 1) of the second member 20 (the right side portion of the broken line B1 shown in FIG. 1). The central portion 21 is formed with the same inner diameter and outer diameter in the axial direction.

[0019] The end portion 22 is formed at the axial end of the second member 20 (the left side portion of the broken line B1 shown in FIG. 1). The end portion 22 has a first end portion 23 and a second end portion 24. The first end portion 23 is formed on the central portion 21 side of the end portion 22 (on the right side of the broken line B2 and on the left side of the broken line B1 shown in FIG. 1), and the second end portion 24 is formed on the tip side of the end portion 22 (the left side of the broken line B2 shown in FIG. 1).

[0020] The first end portion 23 has a first inclined portion 23a and a second inclined portion 23b. The first inclined portion 23a is formed on the central portion 21 side of the first end portion 23, and the second inclined portion 23b is formed on the second end portion 24 side of the first end portion 23. The first inclined portion 23a gradually increases in both inner diameter and outer diameter from the second end portion 24 side toward the central portion 21 side. The second inclined portion 23b gradually increases in both inner diameter and outer diameter from the central portion 21 side toward the second end portion 24 side. Thus, the first end portion 23 is composed of the first inclined portion 23a and the second inclined portion 23b, and a convex portion protruding radially inward is formed over the entire circumferential direction.

[0021] The second end portion 24 is formed with the same inner diameter and outer diameter in the axial direction.

[0022] The outer diameter of the first end portion 23 is formed smaller than the outer diameters of the central portion 21 and the second end portion 24. The inner diameter of the first end portion 23 is formed smaller than the inner diameters of the central portion 21 and the second end portion 24.

[0023] The outer diameter of the second end portion 24 is formed to be the same as the outer diameter of the central portion 21. The inner diameter of the second end portion 24 is formed to be the same as the inner diameter of the central portion 21.

[0024] The reduction in diameter of the central section 21 and the first end 23 relative to the second end 24 is achieved by rolling. However, the reduction in diameter of this pipe may be achieved by methods other than rolling.

[0025] The first member 10 and the second member 20 are both formed with a thickness of 2 to 5 mm. The central portion 11 of the first member 10 and the central portion 21 of the second member 20 are both formed with an outer diameter of 50 to 100 mm. However, the thickness and outer diameter are not limited to this range and may be freely changed.

[0026] The outer diameter D11 of the central portion 11 of the first member 10 and the outer diameter D21 of the central portion 21 of the second member 20 are formed to be substantially the same. That is, the first member 10 before the diameter reduction of the end portion 12 and the second member 20 before the diameter reduction of the first end portion 23 are made of steel pipes with substantially the same outer diameter. In this specification, "substantially the same" means allowing for differences of a manufacturing tolerance.

[0027] Next, the joining procedure for the member joining structure 30 according to Embodiment 1 will be described using Figures 2 and 3. The joining procedure includes the steps of inserting the end portion 12 of the first member 10 into the inside of the end portion 22 of the second member 20, and expanding the diameter of the end portion 14a of the first member 10.

[0028] First, as shown in Figure 2, the end 12 of the first member 10 is inserted inside the end 22 of the second member 20.

[0029] Here, the outer diameter D14 of the end portion 14a of the first member 10 is formed to be smaller than the minimum inner diameter D23 of the first end portion 23 of the second member 20. Therefore, the end portion 14a of the first member 10 can be inserted inside the first inclined portion 23a of the second member 20.

[0030] Furthermore, the minimum outer diameter D13 of the first end 13 of the first member 10 is smaller than the inner diameter D24 of the second end 24 of the second member 20. Therefore, the first end 13 of the first member 10 can be inserted inside the second end 24 of the second member 20.

[0031] Furthermore, the minimum outer diameter D13 of the first end 13 of the first member 10 is larger than the minimum inner diameter D23 of the first end 23 of the second member 20. For this reason, the first end 13 of the first member 10 cannot fit inside the first end 23 of the second member 20.

[0032] Next, as shown in Figure 3, the end portion 14a of the first member 10 is enlarged. Specifically, the end portion 14a is enlarged so that its inner and outer diameters gradually increase from the inclined portion 14b side toward the tip side.

[0033] The diameter of the end portion 14a is increased by inserting a punch having a tapered portion into the second member 20 from the central portion 21 side and pressing the tapered portion against the end portion 14a. However, the diameter of the end portion 14a may be increased by other methods. The diameter of the end portion 14a is increased until the outer circumferential surface of the end portion 14a contacts the inner circumferential surface of the first inclined portion 23a of the second member 20.

[0034] Due to the enlargement of the end portion 14a, the second end portion 14 of the first member is formed by the end portion 14a and the inclined portion 14b, creating a recess that is radially inwardly recessed along its entire circumference. Furthermore, the maximum outer diameter D14a of the end portion 14a is larger than the minimum inner diameter D23 of the first end portion 23 of the second member 20. In this way, the member joining structure 30 is formed.

[0035] The member joining structure 30 is such that the end 12 of the first member 10 and the end 22 of the second member 20 are positioned to overlap in the axial direction (the X-axis direction shown in Figure 3). Specifically, the first end 13 of the first member 10 and the second end 24 of the second member 20 are positioned to overlap in the axial direction. In addition, the second end 14 of the first member 10 and the first end 23 of the second member 20 are positioned to overlap in the axial direction.

[0036] As shown in Figure 3, the member joining structure 30 is such that a protrusion formed on the first end 23 of the second member 20 fits into a recess formed on the second end 14 of the first member 10. Because the first member 10 and the second member 20 are fitted together by a recess and protrusion, the pull-out strength between the first member 10 and the second member 20 can be improved.

[0037] In the member joining structure 30, the outer diameter D11 of the central portion 11 of the first member 10 and the outer diameter D21 of the central portion 21 of the second member 20 are formed to be substantially the same. Therefore, no gap is created in the radial direction between the first member 10 and the second member 20, and the space can be used effectively.

[0038] In the above embodiment, both the first and second members were cylindrical pipes, but they may also be cylindrical pipes with curves, or even joints.

[0039] In the above embodiment, the first and second members were formed from an iron alloy, but they may also be alloys of metals such as aluminum, titanium, tin, lead, or magnesium.

[0040] In the above embodiment, the diameter of the pipe was reduced twice with respect to the first member to form pipes of three different diameters, but the diameter reduction of the pipe can be done once or three or more times.

[0041] The cross-sections of the recess formed at the second end of the first member and the protrusion formed at the first end of the second member can be in various shapes, such as triangles, rectangles, or arcs.

[0042] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of Symbols]

[0043] 10. First component 11, 21...Central part 12, 22...ends 13, 23...1st end 14, 24...2nd end 20...Second component 30. Joining structure of components

Claims

1. A joining structure for members, comprising a first member having a hollow circular cross-section and a second member having a hollow circular cross-section, The end of the first member is inserted inside the end of the second member. A recess is formed at the end of the first member, which is recessed radially inward. A convex portion is formed at the end of the second member, which protrudes radially inward. The protrusion formed on the end of the second member is fitted into the recess formed on the end of the first member. The joining structure of the components.

2. The end of the first member is reduced in diameter relative to the central part of the first member. The outer diameter of the central portion of the first member and the outer diameter of the central portion of the second member are formed to be substantially the same. The joining structure of the member according to claim 1.

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