Fastening member

Abstract

The present invention provides a fastening member capable of suppressing an increase in weight while enabling fastening to be stable. A fastening member (10, 50) is provided with: a thread-forming section (11, 51); and seat surface forming portions (12, 52) including seat surfaces (12a, 52a) that abut against the members (40) to be fastened. The seat surface-forming sections (12, 52) include flange sections (122, 522) that are formed in a shape expanding radially outward and that apply a compressive force to the member (40) to be fastened, the flange sections (122, 522) being formed in a position close to the seat surfaces (12a, 52a). The flange parts (122, 522) include inclined surfaces (122c, 122d) that are inclined so as to approach the seat surfaces (12a, 52a) from the inside toward the outside in the radial direction on the opposite surfaces of the seat surfaces (12a, 52a). The inclined surfaces (122c, 122d) include: an inner inclined surface (122c); and an outer inclined surface (122d) that is positioned further outward in the radial direction than the inner inclined surface (122c) and that has a larger inclination angle with respect to the seat surfaces (12a, 52a) than the inner inclined surface (122c).

Description

Technical Field

[0001] The present invention relates to a fastening member. Background Art

[0002] In Patent Document 1, an annular groove is provided in a washer for a fastening portion between a vehicle component and a vehicle structure. And an effect of "thereby, the fastening can be made firm, and as a result, the handling stability of the vehicle is improved" is disclosed.

[0003] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent No. 6400647 Summary of the Invention Problems to be Solved by the Invention According to the above technique, since a washer is added to the fastening portion, the vehicle weight increases. As a means of making the fastening firm without using a washer, it is conceivable to use a flanged fastening member (for example, a flanged bolt or a flanged nut). However, if the rigidity of the flanged bolt is to be increased in order to make the fastening more firm, it is necessary to increase the wall thickness of the flange portion. As a result, the weight of the flanged bolt increases.

[0004] The present invention has been completed in view of the above background, and an object thereof is to provide a fastening member capable of making the fastening firm while suppressing an increase in weight.

[0005] Means for Solving the Problems One aspect of the present invention is a fastening member, The fastening member includes: a thread forming portion formed with an external thread or an internal thread; and a seat surface forming portion including a seat surface that abuts against a member to be fastened, The seat surface forming portion includes, in a portion close to the seat surface, a flange portion formed in a shape that expands radially outward and for applying a compressive force to the member to be fastened, The flange portion includes, on the opposite side of the seat surface, an inclined surface that inclines from the inside toward the outside in the radial direction so as to approach the seat surface, The inclined surface includes: an inner inclined surface; and an outer inclined surface located at a position radially outside the inner inclined surface and having a larger inclination angle with respect to the seat surface than the inner inclined surface.

[0006] Another aspect of the present invention is a fastening member, The fastening member includes: a thread forming portion formed with an external thread or an internal thread; and A seat surface forming portion including a seat surface that abuts against a fastened member. The seat surface forming portion includes, at a position close to the seat surface, a flange portion that is formed in a shape extending radially outward and is configured to apply a compressive force to the fastened member. The flange portion includes a recess formed on the opposite surface of the seat surface. The recess is formed such that the outermost edge of the recess in the radial direction is located at the position closest to the seat surface.

[0007] Advantages of the Invention According to one aspect of the present invention, an outer inclined surface having an inclination angle larger than that of an inner inclined surface is located at a position radially outside the inner inclined surface. Thus, in the flange portion, it is possible to increase the wall thickness of the radially inner portion where the contribution to rigidity is large. As a result, the rigidity of the flange portion can be improved. In addition, in the flange portion, an increase in the wall thickness of the radially outer portion where the axial stress is small can be suppressed. As a result, an increase in the weight of the fastening member can be suppressed.

[0008] According to another aspect of the present invention, in the flange portion, a recess is formed on the opposite surface of the seat surface. Thus, it is possible to form a concentration point of the internal stress of the flange portion during fastening in the recess. Therefore, compared with the case where the concentration point of the internal stress of the flange portion is only the innermost diameter portion of the flange portion, the fastening can be made more secure. In addition, the recess is formed such that the outermost edge of the recess in the radial direction is located at the position closest to the seat surface. Therefore, a decrease in the rigidity of the flange portion due to the formation of the recess can be strongly suppressed.

[0009] As described above, according to the above aspects, it is possible to provide a fastening member that can make the fastening secure while suppressing an increase in weight.

[0010] It should be noted that the reference numerals in parentheses described in the technical solution indicate the correspondence with the specific means described in the following embodiments, and do not limit the technical scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is an axial cross-sectional view showing a fastening structure in a first embodiment. Figure 2 is a view of Figure 1 the enlarged flange portion in an axial cross-sectional view. Figure 3 is a view showing the stress analysis result of the first embodiment. Figure 4 is an axial cross-sectional view showing a flange portion of a fastening structure in a second embodiment. Figure 5 is an axial cross-sectional view showing a flange portion of a fastening structure in a third embodiment. Figure 6It is an axial sectional view showing the fastening structure in the fourth embodiment.

[0012] Explanation of Reference Numerals 10, 50: First fastening member; 11, 51: Thread forming portion; 12, 52: Seat surface forming portion; 12a, 52a: Seat surface; 122, 522: Flange portion; 122a: Outermost contact portion; 122c: Inner inclined surface; 122d: Outer inclined surface; 122e, 122k: Recess; 122f: Outermost diameter portion; 122i: Innermost diameter portion; 40: Second fastened member (fastened member); L1: Imaginary line. Detailed Description of the Embodiment

[0013] The fastening member includes a thread forming portion and a seat surface forming portion. The seat surface forming portion includes, in a portion close to the seat surface, a flange portion that is formed in a shape that expands radially outward and is used to apply a compressive force to the fastened member. The flange portion includes, on the opposite side of the seat surface, an inclined surface that is inclined so as to approach the seat surface from the inside toward the outside in the radial direction. The inclined surface includes an inner inclined surface and an outer inclined surface that is located on the radially outer side of the inner inclined surface and has a larger inclination angle with respect to the seat surface than the inner inclined surface.

[0014] In the fastening member, the boundary between the inner inclined surface and the outer inclined surface may be located on the radially inner side of the outermost contact portion that contacts the fastened member at the outermost position in the radial direction on the seat surface. At this boundary, the inclination angle changes. As a result, in the flange portion, an increase in the wall thickness of the radially outer portion where the axial stress is small can be effectively suppressed.

[0015] In the fastening member, the inclination angle of the inner inclined surface may be 20° to 30°, and the inclination angle of the outer inclined surface may be 35° to 50°. As a result, in the flange portion, the wall thickness of the radially inner portion that makes a large contribution to the rigidity can be effectively increased. In addition, in the flange portion, an increase in the wall thickness of the radially outer portion where the axial stress is small can be effectively suppressed.

[0016] In the fastening member, the flange portion may also include, on the opposite side of the seat surface, a recess formed between the inner inclined surface and the outer inclined surface. As a result, a stress concentration point of the inner stress of the flange portion during fastening can be formed in the recess. As a result, compared with the case where the stress concentration point of the inner stress of the flange portion is only the innermost diameter portion of the flange portion, the fastening can be made more stable.

[0017] In the fastening member, the recess may also be formed at a position radially inner than the outermost contact portion that contacts the fastened member at the outermost position in the radial direction on the seat surface. As a result, the axial stress can be effectively applied to the fastened member through the stress concentration point formed by the recess. As a result, the fastening can be made more stable.

[0018] In the fastening member, the recess may also be formed in a shape that cuts the opposite surface of the seating surface into an L shape in the axial cross-section. Thereby, a reduction in the rigidity of the flange portion caused by the recess can be suppressed. Further, a concentration point of the internal stress of the flange portion at the time of fastening can be effectively formed in the recess.

[0019] In the fastening member, the recess may also be formed in a shape in which the outermost edge of the recess in the radial direction is located at the position closest to the seating surface. Thereby, a reduction in the rigidity of the flange portion caused by the recess can be suppressed.

[0020] In the fastening member, the recess may be formed in the radial direction between the innermost diameter portion and the outermost contact portion. The innermost diameter portion is located at the innermost position in the radial direction in the flange portion, and the outermost contact portion contacts the member to be fastened at the outermost position in the radial direction on the contact surface. Further, the recess may be formed in the axial direction between the outermost diameter portion and the innermost diameter portion. The outermost diameter portion is located at the outermost position in the radial direction in the flange portion, and the innermost diameter portion is located at the innermost position in the radial direction in the flange portion. Thereby, a reduction in the rigidity of the flange portion caused by the recess can be suppressed. Further, a concentration point of the internal stress of the flange portion at the time of fastening can be effectively formed in the recess.

[0021] In the fastening member, the recess may also be configured to intersect with an imaginary line. The imaginary line bisects the radial distance between the innermost diameter portion and the outermost contact portion and is parallel to the axial direction. Thereby, a reduction in the rigidity of the flange portion caused by the recess can be suppressed. Further, a concentration point of the internal stress of the flange portion at the time of fastening can be effectively formed in the recess.

[0022] In the fastening member, the inner inclined surface and the outer inclined surface may also be formed in a linear conical shape in the axial cross-section. Thereby, in the flange portion, the wall thickness of the radially inner portion having a large contribution to the rigidity can be effectively increased. Further, in the flange portion, an increase in the wall thickness of the radially outer portion having a small axial stress can be effectively suppressed.

[0023] (First Embodiment) 1. Configuration of the fastening structure 1 Refer to Figures 1 to 3 The fastening structure 1 in the first embodiment will be described. In the fastening structure 1, the rear shock absorber constituting the running part of the motor vehicle is fastened to the vehicle body of the motor vehicle using the first fastening member 10.

[0024] As Figure 1As shown, the fastening structure 1 in the first embodiment includes a first fastening member 10, a second fastening member 20, a first fastened member 30, and a second fastened member 40. In the fastening structure 1, the first fastened member 30 and the second fastened member 40 are fastened using the first fastening member 10 and the second fastening member 20. In the first embodiment, the first fastened member 30 is, for example, a steel plate that forms the body of a motor vehicle, and the second fastened member 40 is, for example, a bracket for fixing the rear shock absorber of the motor vehicle to the body of the motor vehicle.

[0025] As Figure 1 shown, the first fastening member 10 is a bolt that includes a thread-forming portion 11 and a seat surface-forming portion 12. In the first embodiment, the first fastening member 10 is, for example, a bolt with a thread diameter (nominal diameter) of 10 mm. The thread-forming portion 11 is a bolt shaft portion on which an external thread 11a is formed. The seat surface-forming portion 12 is a bolt head that includes a seat surface 12a that abuts against the second fastened member 40. The seat surface-forming portion 12 is arranged coaxially with the thread-forming portion 11, and the radial dimension of the seat surface-forming portion 12 is larger than the radial dimension of the thread-forming portion 11. As Figure 1 shown, the external thread 11a of the thread-forming portion 11 may be formed only in the middle portion of the thread-forming portion 11. Although not shown, it may also be formed across the entire length of the thread-forming portion 11.

[0026] The first fastening member 10 is, for example, a flanged bolt. That is, the seat surface-forming portion 12 of the first fastening member 10 is a flanged bolt head. Specifically, the seat surface-forming portion 12 includes a head body 121 and a flange portion 122. In the first embodiment, the head body 121 is formed in the shape of a hexagonal head, but the head body 121 may also be formed in a shape other than a hexagon, or may be formed in the shape of a perforated head. The flange portion 122 is formed in a shape that extends radially outward in the circumferential direction at a portion of the seat surface-forming portion 12 close to the seat surface 12a, so that a compressive force acts on the second fastened member 40. The seat surface 12a of the seat surface-forming portion 12 is continuously formed by the bottom surface of the head body 121 and the bottom surface of the flange portion 122.

[0027] In the first embodiment, the width across flats (the diameter of the inscribed circle of the head body 121) of the head body 121 of the seat surface-forming portion 12 is larger than the diameter of the thread-forming portion 11. In addition, the diameter of the flange portion 122 of the seat surface-forming portion 12 is larger than the diameter of the thread-forming portion 11 and the width across flats of the head body 121.

[0028] The second fastening member 20 is, for example, a nut formed with an internal thread that engages with the external thread 11a of the first fastening member 10. In the first embodiment, the second fastening member 20 is a welded nut that is fixed to the first fastened member 30 by pre-welding. As the second fastening member 20, a flanged nut separate from the first fastened member 30 or a non-flanged nut separate from the first fastened member 30 may also be used.

[0029] 2. Detailed configuration of the seat surface forming portion 12 of the first fastening member 10 Hereinafter, in the seat surface 12a of the seat surface forming portion 12, the portion that is the outermost in the radial direction and abuts against the second fastened member 40 is defined as the outermost abutting portion 122a. As Figure 2 shown, the flange portion 122 has a chamfered portion 122b formed when the first fastening member 10 is cast and molded, near the seat surface 12a and radially outside the outermost abutting portion 122a.

[0030] The entire opposite surface of the seat surface 12a in the flange portion 122 is inclined so as to approach the seat surface 12a from the inside toward the outside in the radial direction. Hereinafter, the opposite surface of the seat surface 12a in the flange portion 122 is defined as the inclined surface.

[0031] The inclined surface of the flange portion 122 includes an inner inclined surface 122c, an outer inclined surface 122d, and a concave portion 122e. The inner inclined surface 122c is connected to the head main body 121. The outer inclined surface 122d is located at a position radially outside the inner inclined surface 122c. In other words, the inner inclined surface 122c is located radially inside in the inclined surface of the flange portion 122, and the outer inclined surface 122d is located radially outside in the inclined surface of the flange portion 122.

[0032] Hereinafter, the angle that is an acute angle with respect to the seat surface 12a is simply defined as the inclination angle. The inclination angle of the outer inclined surface 122d is larger than the inclination angle of the inner inclined surface 122c. The inclination angle of the inner inclined surface 122c is preferably 20° to 30°, and the inclination angle of the outer inclined surface 122d is preferably 35° to 50°. In the first embodiment, the inclination angle of the inner inclined surface 122c is 25°, and the inclination angle of the outer inclined surface 122d is 40°.

[0033] In the first embodiment, the outer inclined surface 122d is formed to the outermost diameter portion 122f of the flange portion 122. The flange portion 122 has a predetermined thickness t1 between the outermost diameter portion 122f and the seat surface 12a.

[0034] By making the inclination angle of the outer inclined surface 122d larger than that of the inner inclined surface 122c, the following effects are obtained. It is possible to increase the wall thickness of the flange portion 122 near the head main body 121 where the contribution to rigidity is large. As a result, the rigidity of the flange portion 122 can be improved. Further, it is possible to suppress an increase in the wall thickness of the radially outer portion where the axial stress in the flange portion 122 is small. As a result, an increase in the weight of the first fastening member 10 can be suppressed.

[0035] The recess 122e is formed in the inclined surface of the flange portion 122. The recess 122e is formed in an annular shape over the entire circumference of the flange portion 122. In the first embodiment, the recess 122e is formed at the boundary between the inner inclined surface 122c and the outer inclined surface 122d. In other words, the recess 122e is connected to the inner inclined surface 122c on the radially inner side and to the outer inclined surface 122d on the radially outer side.

[0036] In the first embodiment, the inclined surface of the flange portion 122 is formed in a stepped shape by the recess 122e. The recess 122e is formed in a shape that cuts the inclined surface of the flange portion 122 into an L shape in the axial cross section. Specifically, the recess 122e includes: a wall surface that extends substantially parallel to the axial direction Y of the first fastening member 10 from the connecting portion 122g connected to the inner inclined surface 122c; and a bottom surface that extends in a direction substantially orthogonal to the axial direction Y of the first fastening member 10 from the connecting portion 122h connected to the outer inclined surface 122d. Thus, the recess 122e is formed in a shape that approaches the seat surface 12a from the inner side toward the outer side in the radial direction. In addition, the recess 122e is formed in a shape such that the outermost edge of the recess is located at the position closest to the seat surface 12a in the radial direction.

[0037] In Figure 2 the recess 122e is formed inside the imaginary rectangle S1 indicated by the double-dashed line. Specifically, the recess 122e is formed in the radial direction of the first fastening member 10 between the innermost diameter portion 122i and the outermost contact portion 122a of the flange portion 122. The recess 122e is formed in the axial direction Y of the first fastening member 10 between the innermost diameter portion 122i and the outermost diameter portion 122f of the flange portion 122.

[0038] In the first embodiment, the recess 122e is configured to intersect the imaginary line L1. The imaginary line L1 bisects the radial distance between the innermost diameter portion 122i and the outermost contact portion 122a of the flange portion 122 and is parallel to the axial direction Y.

[0039] By forming the concave portion 122e in the flange portion 122, a concentration point of the internal stress of the flange portion 122 can be formed in the concave portion 122e when the first fastened member 30 and the second fastened member 40 are fastened by the first fastening member 10 and the second fastening member 20. Thus, compared with the case where the concentration point of the internal stress of the flange portion 122 is only located at the innermost diameter portion 122i of the flange portion 122, the moment when an external force for peeling the second fastened member 40 from the first fastened member 30 acts on the outermost diameter portion of the second fastened member 40 can be reduced. Therefore, the fastening of the first fastened member 30 and the second fastened member 40 by the first fastening member 10 and the second fastening member 20 can be made firm.

[0040] 3. Analysis of the fastening structure 1 Refer to Figure 3 The analysis related to the fastening structure 1 will be described. The analysis results of the analysis example 1 corresponding to the first embodiment are shown as (a) in Figure 3 , the analysis results of the analysis example 2 are shown as (b) in Figure 3 , and the analysis results of the analysis example 3 are shown as (c) in Figure 3 .

[0041] The analysis models used in the analysis examples 1 to 3 are three-dimensional models including the first fastening member 10, the first fastened member 30, and the second fastened member 40.

[0042] In Figure 3 In the analysis example 1 shown as (a) in, the inclination angle of the inner inclined surface 122c is 25°, the inclination angle of the outer inclined surface 122d is 40°, and an analysis model formed with the concave portion 122e is used.

[0043] In Figure 3 In the analysis example 2 shown as (b) in, the inclination angle of the inclined surface of the flange portion 122 is constantly 25° without change, and an analysis model in which the concave portion 122e of the first embodiment is not formed in the flange portion 122 is used.

[0044] In Figure 3 In the analysis example 3 shown as (c) in, the inclination angle of the inclined surface of the flange portion 122 is constantly 25° without change, and an analysis model in which the concave portion 122e similar to the first embodiment is formed in the flange portion 122 is used.

[0045] In the analysis models used in the analysis examples 1 to 3, the first fastened member 30 is made of structural steel, the second fastened member 40 is made of aluminum alloy, the Young's modulus of the first fastening member 10 is 206 GPa, the Poisson's ratio is 0.3, and the yield stress is 1017 MPa.

[0046] Among these analytical models, the axial force generated by the first fastening member 10 is 38.6 kN, and a load of 8.4 kN is applied to the outermost diameter portion of the second fastened member 40 in a direction to peel the second fastened member 40 from the first fastened member 30. Figure 3 in (a) - Figure 3 The analysis results of Analysis Examples 1 - 3 shown in (c) in

[0047] are represented by contour maps of axial stress, and the greater the stress, the darker the color. Figure 3 By comparing Analysis Example 2 shown in (b) in Figure 3 with Analysis Example 3 shown in (c) in Figure 3 , the influence of the concave portion 122e on the axial stress can be known. By comparing Figure 3 Analysis Example 3 shown in (c) in

[0048] with Analysis Example 1 shown in (a) in Figure 3 , the influence of making the inclination angle of the outer inclined surface 122d larger than that of the inner inclined surface 122c can be known.

[0049] In contrast, in Figure 3 Analysis Example 2 shown in (b) in Figure 3 , the concentration point of the axial stress is formed at the innermost diameter portion 122i of the flange portion 122 in the flange portion 122, and the axial stress transmitted to the radially outer portion in the flange portion 122 becomes smaller.

[0050] On the contrary, in Figure 3 Analysis Example 3 shown in (c) in

[0051] 4. Effects According to the first fastening member 10 in the first embodiment, the outer inclined surface 122d of the flange portion 122 of the first fastening member 10 has a larger inclination angle than the inner inclined surface 122c. Therefore, in the flange portion 122, the wall thickness closer to the head main body 121 with a greater contribution to rigidity can be increased. As a result, the rigidity of the flange portion 122 can be improved. Further, in the flange portion 122, an increase in the wall thickness of the radially outer portion with a small axial stress can be suppressed. As a result, an increase in the weight of the first fastening member 10 can be suppressed. Therefore, while suppressing an increase in the weight of the first fastening member 10, the fastening based on the first fastening member 10 can be made firm.

[0052] According to the first fastening member 10 in the first embodiment, the boundary between the inner inclined surface 122c and the outer inclined surface 122d is located at a position radially inside the outermost contact portion 122a. At this boundary, the inclination angle changes. Thereby, in the flange portion 122, an increase in the wall thickness of the radially outer portion with a small axial stress can be effectively suppressed.

[0053] According to the first fastening member 10 in the first embodiment, the inclination angle of the inner inclined surface 122c is 20° to 30°, and the inclination angle of the outer inclined surface 122d is 35° to 50°. Thereby, in the flange portion 122, the wall thickness closer to the head main body 121 with a greater contribution to rigidity can be effectively increased. In addition, in the flange portion 122, an increase in the wall thickness of the radially outer portion with a small axial stress can be effectively suppressed.

[0054] According to the first fastening member 10 in the first embodiment, a recess 122e is formed in the inclined surface of the flange portion 122. Therefore, a concentration point of the internal stress of the flange portion 122 during fastening can be formed in the recess 122e. Therefore, compared with the case where the concentration point of the internal stress of the flange portion 122 is only the innermost diameter portion 122i of the flange portion 122, the fastening can be made firm.

[0055] According to the first fastening member 10 in the first embodiment, the recess 122e is formed radially inside the outermost contact portion 122a of the flange portion 122. Thereby, the axial stress can be effectively applied to the second fastened member 40 through the concentration point of the internal stress formed by the recess 122e. As a result, the fastening can be made more firm.

[0056] According to the first fastening member 10 in the first embodiment, the recess 122e is formed in a shape that cuts the inclined surface of the flange portion 122 into an L shape in the axial cross section. Thereby, a decrease in the rigidity of the flange portion 122 caused by the recess 122e can be suppressed. Further, a concentration point of the internal stress of the flange portion 122 during fastening can be effectively formed in the recess 122e.

[0057] According to the first fastening member 10 in the first embodiment, the recess 122e is formed in a shape such that the outermost edge of the recess 122e in the radial direction is located at the position closest to the seating surface 12a. Thereby, a reduction in the rigidity of the flange portion 122 caused by the recess 122e can be suppressed.

[0058] According to the first fastening member 10 in the first embodiment, the recess 122e is formed in the radial direction between the innermost diameter portion 122i and the outermost contact portion 122a of the flange portion 122. Further, the recess 122e is formed in the axial direction between the outermost diameter portion 122f and the innermost diameter portion 122i of the flange portion 122. Thereby, a reduction in the rigidity of the flange portion 122 caused by the recess 122e can be suppressed. Further, a concentration point of the internal stress of the flange portion 122 during fastening can be effectively formed in the recess 122e.

[0059] According to the first fastening member 10 in the first embodiment, the recess 122e is configured to intersect with the imaginary line L1. The imaginary line L1 bisects the radial distance between the innermost diameter portion 122i and the outermost contact portion 122a and is parallel to the axial direction Y. Thereby, a reduction in the rigidity of the flange portion 122 caused by the recess 122e can be suppressed. Further, a concentration point of the internal stress of the flange portion 122 during fastening can be effectively formed in the recess 122e.

[0060] According to the first fastening member 10 in the first embodiment, the inner inclined surface 122c and the outer inclined surface 122d are formed in a tapered shape that is linear in the axial cross-section. Thereby, in the flange portion 122, the wall thickness of the radially inner portion where the contribution to the rigidity is large can be effectively increased. Further, in the flange portion 122, an increase in the wall thickness of the radially outer portion where the axial stress is small can be effectively suppressed.

[0061] (Second Embodiment) In the above first embodiment, the recess 122e is formed in a shape that cuts the inclined surface of the flange portion 122 into an L shape in the axial cross-section. In the second embodiment, as Figure 4 shown, the recess 122k formed in the inclined surface of the flange portion 122 is formed in a shape that cuts the inclined surface of the flange portion 122 into an arc shape in the axial cross-section.

[0062] In the axial cross-section of the flange portion 122, the connection line (not shown) of the recess 122k in the connection portion 122h connected to the outer inclined surface 122d is parallel to the seating surface 12a. Thereby, the recess 122k is formed in a shape that approaches the seating surface 12a from the inside to the outside in the radial direction. Further, the recess 122k is formed in a shape such that the outermost edge of the recess in the radial direction is located at the position closest to the seating surface 12a.

[0063] In the second embodiment, since a concave portion 122k is formed on the inclined surface of the flange portion 122 as in the first embodiment, a concentration point of the internal stress of the flange portion 122 at the time of fastening can be formed in the concave portion 122k. Therefore, compared with the case where the concentration point of the internal stress of the flange portion 122 is only the innermost diameter portion 122i of the flange portion 122, the fastening can be made firm.

[0064] (Third Embodiment) In the first and second embodiments, an inner inclined surface 122c, an outer inclined surface 122d, and concave portions 122e and 122k are formed on the inclined surface of the flange portion 122. In the third embodiment, as Figure 5 shown, concave portions 122e and 122k are not formed on the inclined surface of the flange portion 122, and only the inner inclined surface 122c and the outer inclined surface 122d are formed.

[0065] In the third embodiment, the effects based on the inner inclined surface 122c and the outer inclined surface 122d can be achieved in the same manner as in the first and second embodiments. That is, the inclination angle of the outer inclined surface 122d of the flange portion 122 is larger than the inclination angle of the inner inclined surface 122c. Thus, in the flange portion 122, the wall thickness near the head main body 121 having a large contribution to the rigidity can be increased. As a result, the rigidity of the flange portion 122 can be improved. Further, in the flange portion 122, an increase in the wall thickness of the radially outer portion where the axial stress is small can be suppressed. As a result, an increase in the weight of the first fastening member 10 can be suppressed. Therefore, while suppressing an increase in the weight of the first fastening member 10, the fastening based on the first fastening member 10 can be made firm.

[0066] (Fourth Embodiment) In the first embodiment, the first fastening member 10 is a flanged bolt, and the second fastening member 20 is a nut. An inner inclined surface 122c, an outer inclined surface 122d, and a concave portion 122e are formed on the inclined surface of the flange portion 122 of the first fastening member 10. In contrast, as Figure 6 shown, in the fourth embodiment, the first fastening member 50 is a flanged nut, and the second fastening member 60 is a bolt. An inner inclined surface, an outer inclined surface, and a concave portion similar to those in the first embodiment are formed on the inclined surface of the flange portion 522 of the first fastening member 50.

[0067] The second fastening member 60 may be a welding bolt fixed to the first fastened member 30 by pre-welding, or a flanged bolt separated from the first fastened member 30 or a non-flanged bolt separated from the first fastened member 30 may be used.

[0068] The first fastening member 50 includes a thread forming portion 51 and a seat surface forming portion 52. The thread forming portion 51 constitutes the portion of the first fastening member 50 close to the central axis. An internal thread 51a is formed in the thread forming portion 51. The seat surface forming portion 52 constitutes the outer peripheral side portion of the first fastening member 50. A seat surface 52a that abuts against the second fastened member 40 is formed in the seat surface forming portion 52. The seat surface forming portion 52 includes a nut body 521 and a flange portion 522. In the fourth embodiment, the nut body 521 is formed in a hexagonal prism shape.

[0069] The flange portion 522 is formed in a shape that expands radially outward in the circumferential direction at the portion of the seat surface forming portion 52 close to the seat surface 52a, so that a compressive force acts on the second fastened member 40. The seat surface 52a of the seat surface forming portion 52 is continuously formed by the bottom surface of the nut body 521 and the bottom surface of the flange portion 522.

[0070] On the opposite surface of the seat surface 52a in the flange portion 522, an inner inclined surface, an outer inclined surface, and a concave portion are formed in the same manner as in the first embodiment. Since the specific configurations of the inner inclined surface, the outer inclined surface, and the concave portion are the same as those in the first embodiment, detailed descriptions thereof are omitted.

[0071] In the fourth embodiment, since the inner inclined surface, the outer inclined surface, and the concave portion are formed in the flange portion 522 of the first fastening member 50 in the same manner as in the first embodiment, the same effects as those in the first embodiment can be achieved.

[0072] (Other embodiments) In the above embodiments, among the first fastening member and the second fastening member, only the first fastening member is formed with the inner inclined surface, the outer inclined surface, and the concave portion, but the inner inclined surface, the outer inclined surface, and the concave portion may be formed on both the first fastening member and the second fastening member.

[0073] In the above embodiments, the inner inclined surface and the outer inclined surface are formed on the inclined surface of the flange portion, and the inclination angle of the inclined surface of the flange portion changes in two stages from the radially inner side toward the radially outer side. However, the inclination angle of the inclined surface of the flange portion may also change in three or more stages. When the inclination angle of the inclined surface of the flange portion is three or more stages, the inclination angles of the two adjacent inclined surfaces located in the concave portion do not necessarily have to be different from each other, and the inclination angles of the two adjacent inclined surfaces located in the concave portion may also be the same as each other.

[0074] In the above-described embodiment, the inclination angles of the inner inclined surface and the outer inclined surface of the flange portion are each constant, and when viewed in an axial cross-section, the inner inclined surface and the outer inclined surface are formed in a straight line shape. However, it is also possible that the inclination angle of at least one of the inner inclined surface and the outer inclined surface is not constant but varies. That is, when viewed in an axial cross-section, at least one of the inner inclined surface and the outer inclined surface may also be curved.

Claims

1. A fastening member (10, 50), wherein: The fastening member (10, 50) comprises: a thread forming portion (11, 51) formed with an external thread (11a) or an internal thread (51a); and a seat surface forming portion (12, 52) including a seat surface (12a, 52a) abutting against a fastened member (40), The seat surface forming portion includes a flange portion (122, 522) at a position close to the seat surface, the flange portion (122, 522) being formed in a shape extending radially outward and used to apply a compressive force to the fastened member. The flange portion includes an inclined surface (122c, 122d) on the opposite side of the seat surface, and the inclined surface (122c, 122d) is inclined in a manner approaching the seat surface from the inside to the outside in the radial direction. The inclined surface comprises: an inner inclined surface (122c); and An outer inclined surface (122d) is located radially outward of the inner inclined surface and has a larger inclination angle relative to the seat surface than the inner inclined surface.

2. The fastening member according to claim 1, wherein The boundary between the inner inclined surface and the outer inclined surface is located radially inward of an outermost contact portion (122a) that contacts the fastened member at the radially outermost portion of the seat surface.

3. The fastening member according to claim 1, wherein The inclination angle of the inner inclined surface is 20° to 30°, The inclination angle of the outer inclined surface is 35°~50°.

4. The fastening member according to claim 1, wherein The flange portion includes a recessed portion (122e, 122k) formed between the inner inclined surface and the outer inclined surface on the opposite surface of the seat surface, The recessed portion is formed radially inward of an outermost contact portion (122a) that contacts the fastened member at the outermost portion in the radial direction of the seat surface.

5. The fastening member according to claim 4, wherein: The recessed portion is formed in a shape obtained by cutting the opposite surface of the seat surface into an L-shape in an axial section.

6. The fastening member according to claim 4, wherein The recessed portion is formed in a shape such that the outermost edge of the recessed portion is located closest to the seat surface in the radial direction.

7. The fastening member according to claim 4, wherein: The recess is formed radially between the innermost diameter portion (122i) located radially innermost in the flange portion and the outermost abutment portion, and is formed axially between the outermost diameter portion (122f) located radially outermost in the flange portion and the innermost diameter portion.

8. The fastening member according to claim 7, wherein: The recessed portion is configured to intersect with an imaginary line (L1) that bisects a radial distance between the innermost diameter portion and the outermost contact portion and is parallel to the axial direction.

9. The fastening member according to any one of claims 1 to 8, wherein The inner inclined surface and the outer inclined surface are formed into a linear tapered shape in an axial section.

10. A fastening member (10, 50), wherein: The fastening member (10, 50) comprises: a thread forming portion (11, 51) formed with an external thread (11a) or an internal thread (51a); and a seat surface forming portion (12, 52) including a seat surface (12a, 52a) abutting against a fastened member (40), The seat surface forming portion includes a flange portion (122, 522) at a position close to the seat surface, the flange portion (122, 522) being formed in a shape extending radially outward and used to apply a compressive force to the fastened member. The flange portion includes a recessed portion (122e, 122k) formed on the opposite side of the seat surface, The recessed portion is formed in a shape such that the outermost edge of the recessed portion is located closest to the seat surface in the radial direction.

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