Fastening structure

Abstract

To provide a fastening structure which can fasten a fastening member and a fastened member by suppressing the idling of a male screw resulting from the withdrawal of the fastening member into an insertion hole of the fastened member when screwing and fastening the male screw from the fastened member side to a laminated body in which the fastened member is laminated on the fastening member, and is easy in manufacturing.SOLUTION: A fastening structure 100 comprises a fastening member 11 in which a female screw or a pilot hole is formed, a fastened member 12 arranged at the fastening member 11 while being laminated thereon, and formed with an insertion hole 14 which is larger than a diameter of the female screw and a diameter of the pilot hole, and a fixing screw 20 penetrating the insertion hole 14 from the fastened member 12 side, fitting into a screw groove of the female screw or an internal peripheral face of the pilot hole, and fixing the fastening member 11 and the fastened member 12. The insertion hole 14 comprises a plurality of protruding parts 17 extending toward the center of the insertion hole 14 in an in-plane direction of the fastened member 12.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a fastening structure in which a plurality of members are fastened together with screws. [Background technology]

[0002] Conventionally, a commonly used fastening structure for fastening multiple components involves overlapping a fastening member having a protrusion that has been plastically deformed into a cylindrical shape by burring a metal plate material with a fastener member having a through hole that is an opening larger than the outer diameter of the protrusion created by burring, and fastening the metal plates together by inserting a fixing screw through the through hole from the fastening member side.

[0003] However, if the thickness of the fastening member on which the protrusion is formed is too thin, the protrusion of the fastening member is drawn into the insertion hole of the fastened member by the tightening of the screw, causing plastic deformation, a so-called "jacking up" phenomenon. If the deformation of the protrusion drawn into the insertion hole is large, the protrusion will enter the area around the incomplete thread part of the fixing screw, causing the fixing screw to spin freely, making it impossible to fasten the metal plates together.

[0004] Furthermore, the above problem occurs in a thin fastening member in which a protrusion that has been plastically deformed into a cylindrical shape is formed, but the same problem may occur in a thin fastening member in which a cylindrical protrusion is not formed. For example, there is a fastening structure in which a thin fastening member is formed with only a through hole without forming a cylindrical protrusion, and a self-tapping screw is screwed into the through hole to form a female thread in the through hole to fasten the fastening member and the fastened member. Even in such a fastening structure, there is a possibility that the fastening member is drawn into the through hole of the fastened member, making it impossible to fasten the fastening member and the fastened member.

[0005] In recent years, the metal sheet materials used in the fastening members of the casings of electrical equipment such as ventilation and air conditioning units have become thinner in order to reduce the weight and cost of the electrical equipment, making it difficult to ensure a fastening structure with a practical level of strength when fastening using fixing screws.

[0006] Patent Document 1 discloses an assembly structure in which a female-threaded member having a protrusion formed by plastically deforming a metal plate into a cylindrical shape and a female thread formed on the inner peripheral surface of the protrusion, and a fastened member having an insertion hole and arranged overlapping the female-threaded member on the opposite side to the side to which the protrusion faces, are fastened by a male-threaded member. In the assembly structure of Patent Document 1, the female-threaded member has multiple convex portions that are raised by plastically deforming multiple positions surrounding the protrusion of the metal plate to the outside of the insertion hole on the same side as the protrusion. As a result, in the assembly structure of Patent Document 1, the rigidity of the metal plate around the protrusion is ensured, and the phenomenon in which the cylindrical portion is drawn into the insertion hole of the fastened member when the fixing screw is tightened is suppressed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2014-009700 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the assembly structure of Patent Document 1, in order to form a convex shape around the protrusion of the fastening member, drawing is required in addition to burring, which complicates the processing and increases the number of steps and processing time required for the processing.

[0009] The present disclosure has been made in consideration of the above, and aims to provide a fastening structure that is easy to manufacture and that enables fastening of the fastening member and the fastened member by suppressing free rotation of the male screw caused by the fastening member being drawn into the insertion hole of the fastened member when a stack in which the fastened member is stacked on top of a fastening member is fastened by tightening a male screw from the fastened member side. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems and achieve the object, the fastening structure according to the present disclosure includes a fastening member having a female thread or a pilot hole formed therein, a fastened member arranged in a stacked manner on the fastening member and having an insertion hole formed therein that is larger than the diameter of the female thread and the diameter of the pilot hole, and a fixing screw that passes through the insertion hole from the fastened member side and fits into a thread groove on the inner peripheral surface of the female thread or the pilot hole to fix the fastening member and the fastened member. The insertion hole has multiple protrusions that protrude in a direction toward the center of the insertion hole in the in-plane direction of the fastened member. The insertion hole is formed in the in-plane direction of the fastened members between a first imaginary circle that is coaxial with the central axis of the female thread or the pilot hole and has a diameter larger than the diameter of the female thread and the diameter of the pilot hole, and a second imaginary circle that is coaxial with the central axis of the insertion hole, has a diameter larger than the diameter of the female thread and the diameter of the pilot hole and is smaller than the first imaginary circle. Effect of the Invention

[0011] According to the present disclosure, when a laminate in which a fastened member is stacked on a fastening member is fastened by tightening a male screw from the fastened member side, it is possible to fasten the fastening member and the fastened member by suppressing free rotation of the male screw caused by the fastening member being drawn into the insertion hole of the fastened member, thereby obtaining a fastening structure that is easy to manufacture. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a top view showing a state in which a fastening member and a fastened member constituting a fastening structure according to a first embodiment are superimposed on each other; [Diagram 2] Cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is an enlarged view of a main part of FIG. 1. [Figure 4] FIG. 1 is a side view of a fixing screw according to a first embodiment; [Diagram 5] FIG. 1 is a top view showing a fastening structure according to a first embodiment; [Figure 6] Cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 13 is a top view showing a fastening structure of a comparative example in which a fastening member is fastened to a fastened member having an insertion hole in which a protrusion is not formed. [Figure 8] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 11 is a top view showing a second pattern of an opening shape of the insertion hole of the fastened members in the fastening structure according to the first embodiment; [Figure 10] FIG. 11 is a top view showing a third pattern of an opening shape of the insertion hole of the fastened members in the fastening structure according to the first embodiment; [Figure 11] FIG. 11 is a top view showing a fourth pattern of an opening shape of the insertion hole of the fastened members in the fastening structure according to the first embodiment; [Figure 12] FIG. 11 is a top view showing a fifth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 13] FIG. 13 is a top view showing a sixth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 14] FIG. 13 is a top view showing a seventh pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 15] FIG. 13 is a top view showing an eighth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 16] FIG. 13 is a top view showing a ninth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 17] FIG. 17 is a top view showing a tenth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 18] FIG. 11 is a top view showing an eleventh pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 19] FIG. 12 is a top view showing a twelfth pattern of an opening shape of an insertion hole of a fastened member in the fastening structure according to the first embodiment; [Figure 20]FIG. 1 is a top view showing a first example of a state in which the centers of a cylindrical protrusion of a fastening member and an insertion hole of a fastened member are misaligned when the fastening member and the fastened member are overlapped; [Figure 21] FIG. 13 is a top view showing a second example of a state in which the centers of the cylindrical protrusion of the fastening member and the insertion hole of the fastened member are misaligned when the fastening member and the fastened member are overlapped. [Figure 22] FIG. 13 is a top view showing a third example of a state in which the centers of the cylindrical protrusion of the fastening member and the insertion hole of the fastened member are misaligned when the fastening member and the fastened member are overlapped. [Figure 23] FIG. 13 is a top view showing a fourth example of a state in which the centers of the cylindrical protrusion of the fastening member and the insertion hole of the fastened member are misaligned when the fastening member and the fastened member are overlapped. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a fastening structure according to an embodiment will be described in detail with reference to the drawings.

[0014] Embodiment 1 FIG. 1 is a top view showing a state in which a fastening member 11 and a fastened member 12 constituting a fastening structure 100 according to the first embodiment are superimposed. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 1 shows a stack in which the fastening member 11 and the fastened member 12 are stacked in parallel before being fixed using a fixing screw 20, as viewed from the fastened member 12 side. FIG. 3 is an enlarged view of a main part of FIG. 1. FIG. 4 is a side view of the fixing screw 20 according to the first embodiment. FIG. 5 is a top view showing the fastening structure 100 according to the first embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. 5 shows the fastening structure 100 according to the first embodiment as viewed from the fastened member 12 side.

[0015] In the first embodiment, the vertical direction in FIG. 1 is the vertical direction of the fastening structure 100 according to the first embodiment, and the left-right direction in FIG. 1 is the left-right direction of the fastening structure 100 according to the first embodiment. The vertical direction of the fastening structure 100 is parallel to the thickness direction of the fastening members 11 in a state where they are stacked in the fastening structure 100, and is parallel to the thickness direction of the fastened members 12 in a state where they are stacked in the fastening structure 100. The vertical direction of the fastening structure 100 can be said to be the stacking direction of the fastening members 11 and the fastened members 12. The left-right direction of the fastening structure 100 is parallel to the in-plane direction of the fastening members 11 in a state where they are stacked in the fastening structure 100, and is parallel to the in-plane direction of the fastened members 12 in a state where they are stacked in the fastening structure 100. The direction when the fastening structure 100 according to the first embodiment is used is not limited.

[0016] The fastening structure 100 according to the first embodiment includes a fastening member 11, a fastened member 12, and a fixing screw 20. In the fastening structure 100 according to the first embodiment, the fastening member 11 made of a metal sheet and the fastened member 12 made of a metal sheet are stacked in parallel and fixed together using the fixing screw 20. That is, in the fastening structure 100, a laminate in which the metal sheets are stacked together is fixed together with a screw.

[0017] The fastening member 11 is a sheet metal member made of metal sheet, and is fixed to the fastened member 12 by a fixing screw 20 in the fastening structure 100. The fastening member 11 is provided with a cylindrical protrusion 13, which is a protrusion formed by plastically deforming a part of the fastening member 11 into a cylindrical shape by processing such as burring.

[0018] The cylindrical protrusion 13 is formed in a cylindrical shape protruding downward from the fastening member 11. That is, the protrusion is a rising portion of a part of the fastening member 11 that rises up, and protrudes in the vertical direction toward the opposite side to the side on which the fastened member 12 is arranged. The cylindrical protrusion 13 has an opening 13d having a columnar shape centered on a central axis 13c of the cylindrical protrusion 13. The central axis 13c of the cylindrical protrusion 13 can be said to be the center of the cylindrical protrusion 13 in the in-plane direction of the fastening member 11.

[0019] The cylindrical protrusion 13 protrudes downward from the first surface 11a of the fastening member 11. The second surface 11b of the fastening member 11, which faces away from the first surface 11a of the fastening member 11, faces upward and faces the first surface 12a of the fastened member 12. The second surface 12b of the fastened member 12, which faces away from the first surface 12a of the fastened member 12, faces upward and faces a screw head 21 of the fixing screw 20, which will be described later.

[0020] The cylindrical protruding portion 13 is not female-threaded, and no thread groove is formed on the inner peripheral surface 13b of the cylindrical protruding portion 13.

[0021] The fastened members 12 are sheet metal members made of metal sheet, and the fastening member 11 is fixed by a fixing screw 20 in the fastening structure 100. The fastened members 12 are formed with an insertion hole 14 that is larger than the outer diameter of the cylindrical protrusion 13 of the fastening member 11 in the in-plane direction of the fastened members 12. That is, the fastened members 12 are formed with an insertion hole 14 that has an opening area larger than the opening 13d of the cylindrical protrusion 13 of the fastening member 11 in the in-plane direction of the fastened members 12.

[0022] The insertion hole 14 is a through hole that penetrates the fastened member 12 in the thickness direction of the fastened member 12. In the fastening structure 100 shown in Figs. 1 and 2, the insertion hole 14 having the opening shape of a first pattern is formed. The insertion hole 14 is provided coaxially with the cylindrical protrusion 13 of the fastening member 11. In other words, the central axis 14c of the insertion hole 14 is coaxial with the central axis 13c of the cylindrical protrusion 13 of the fastening member 11. The central axis 14c of the insertion hole 14 can be said to be the center of the insertion hole 14 in the in-plane direction of the fastened member 12.

[0023] The insertion hole 14 is formed in the in-plane direction of the fastened member 12 in a region between a first imaginary circle 15 and a second imaginary circle 16 with the central axis 13c of the cylindrical protruding portion 13 of the fastening member 11 as the center.

[0024] The first virtual circle 15 is a virtual circle in the in-plane direction of the fastening member 11 and the fastened member 12 that has a larger diameter than the inner diameter 13a of the cylindrical protrusion 13 and is relatively far from the central axis 13c in the in-plane direction of the fastening member 11 and the fastened member 12.

[0025] The second imaginary circle 16 is an imaginary circle in the in-plane direction of the fastening member 11 and the fastened member 12 that is larger in diameter than the inner diameter 13a of the cylindrical protrusion 13 and smaller in diameter than the first imaginary circle 15 and is relatively closer to the central axis 13c.

[0026] That is, the diameter of the first virtual circle 15 is larger than the diameter of the second virtual circle 16. Therefore, the first virtual circle 15 can be said to be a virtual circle on the outer periphery side in the in-plane direction of the fastening member 11 and the fastened member 12. Also, the second virtual circle 16 can be said to be a virtual circle on the inner periphery side in the in-plane direction of the fastening member 11 and the fastened member 12. Here, the range in which the insertion hole 14 is formed in the in-plane direction of the fastened member 12 includes the circumferential region of the first virtual circle 15 and the circumferential region of the second virtual circle 16. The first virtual circle 15 and the second virtual circle 16 are coaxial with the central axis 13c of the cylindrical protrusion 13.

[0027] The insertion hole 14 has a plurality of protrusions 17 on the inner surface of the insertion hole 14 that protrude in a direction toward the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12, i.e., a plurality of protrusions 17 that protrude in a direction toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12.

[0028] The protrusion 17 protrudes from the inner circumferential surface of the insertion hole 14 in a direction toward the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12. The protrusion 17 has the same shape in the thickness direction of the fastened member 12, for example.

[0029] The protrusion 17 can be formed simultaneously with the insertion hole 14 when the insertion hole 14 is formed. The protrusion 17 can be formed integrally with the insertion hole 14, for example, during punching when forming the insertion hole 14 in a metal sheet, and can be easily formed in one punching process. Also, the protrusion 17 can be formed integrally with the insertion hole 14, for example, during cutting when forming the insertion hole 14 in a metal sheet, and can be easily formed in one cutting process. Therefore, in manufacturing the fastening structure 100, the formation of the protrusion 17 does not complicate the processing, and the number of steps and processing time required for processing do not increase.

[0030] Further, the insertion hole 14 has a shape in the in-plane direction of the fastened member 12 such that a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are alternately and continuously connected by curved lines over the entire circumference of each imaginary circle.

[0031] The first peripheral point 15P is a point on the circumference of the opening shape of the insertion hole 14 in the in-plane direction of the workpiece 12, and is a point located on the circumference of the first imaginary circle 15.

[0032] The second circumferential point 16P is a point on the circumference of the opening shape of the insertion hole 14 in the in-plane direction of the fastened workpiece 12, and is a point located on the circumference of the second imaginary circle 16.

[0033] 1 and 2, the insertion hole 14 has a shape in which a curved line alternately connects the first circumferential points 15P (points 15a, 15b, 15c, and 15d) and the second circumferential points 16P (points 16a, 16b, 16c, and 16d) in the in-plane direction of the fastened member 12. In the opening shape of the insertion hole 14, the line connecting the first circumferential point 15P and the second circumferential point 16P can be said to be a connecting line connecting the first circumferential point 15P and the second circumferential point 16P.

[0034] Therefore, the first circumferential point 15P and the second circumferential point 16P are parts of the circumference of the opening shape of the insertion hole 14. In addition, the first circumferential point 15P and the second circumferential point 16P can be said to be bending points where the opening shape of the insertion hole 14 bends.

[0035] 1 and 2 has a shape in which points 16a, 15b, and 16b are connected by an arc-shaped curve, points 16b, 15c, and 16c are connected by an arc-shaped curve, points 16c, 15d, and 16d are connected by an arc-shaped curve, and points 16d, 15a, and 16a are connected by an arc-shaped curve in the in-plane direction of the fastened member 12. As a result, the insertion hole 14 of the first pattern shown in Figs. 1 and 2 has a plurality of protrusions 17 formed toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12.

[0036] That is, the insertion hole 14 has an opening shape with a continuous pattern of projections and recesses in the in-plane direction of the fastened members 12. The insertion hole 14 has an opening shape with a continuous pattern of peaks and valleys in the in-plane direction of the fastened members 12. The insertion hole 14 has an opening shape with a wave shape in the in-plane direction of the fastened members 12.

[0037] The fixing screw 20 is a so-called self-tapping screw. As shown in FIG. 4, the fixing screw 20 is composed of a screw head 21 formed in a disk shape and a cylindrical shank 22 extending from the screw head 21. The shank 22 has a cylindrical shape and has a screw thread 23 formed in a spiral shape on the outer circumferential surface of the cylinder. The shank 22 has a complete screw thread 22a in which a complete screw thread is formed and an incomplete screw thread 22b in which an incomplete screw thread is formed. The incomplete screw thread 22b is a portion located on the screw head 21 side in the cylindrical shape and connected to the screw head 21. The incomplete screw thread 22b is a portion immediately below the screw head 21, i.e., a portion of the shank 22 adjacent to the screw head 21, where no screw thread is formed. The complete screw thread 22a is a portion located on the tip side of the cylindrical shape and connected to the incomplete screw thread 22b.

[0038] In the fastening structure 100, to fasten the fastening member 11 and the fastened member 12 using the fixing screw 20, the fastening member 11 and the fastened member 12 are overlapped in the vertical direction such that the protruding direction of the cylindrical protrusion 13 of the fastening member 11 is opposite to the direction in which the surface of the fastening member 11 facing the fastened member 12 faces, as shown in Figures 5 and 6. That is, in the fastening structure 100, the fastened member 12 with its first surface 11a facing downward is overlapped on the second surface 11b of the fastening member 11.

[0039] Then, the shaft portion 22 of the fixing screw 20 is inserted into the insertion hole 14 from the side of the fastened member 12 in the vertical direction, and further screwed into the inner peripheral surface 13b of the cylindrical protrusion 13 of the fastening member 11. Here, since the fixing screw 20 is a self-tapping screw, the shaft portion 22 passes through the opening 13d of the cylindrical protrusion 13 while forming a groove on the inner peripheral surface 13b of the cylindrical protrusion 13 by the thread 23 formed on the shaft portion 22. As a result, a thread groove 13e is formed on the inner peripheral surface 13b of the cylindrical protrusion 13. Then, the fixing screw 20 is screwed into the inner peripheral surface 13b of the cylindrical protrusion 13, that is, the thread 23 of the fixing screw 20 is fitted into the thread groove 13e on the inner peripheral surface 13b of the cylindrical protrusion 13, thereby fixing the fastening member 11 and the fastened member 12.

[0040] In this way, by screwing the shaft 22 of the fixing screw 20 into the inner peripheral surface 13b of the cylindrical protrusion 13, a force in a direction toward the fastening member 11, i.e., a downward force, acts on the fastened member 12. Meanwhile, a force in a direction toward the fastened member 12, i.e., an upward force, acts on the cylindrical protrusion 13 of the fastening member 11. In other words, a force pressing the fastening member 11 and the fastened member 12 against each other acts on each other, and the fixing screw 20 is fastened.

[0041] Here, in order to explain the effect of the fastening structure 100 according to embodiment 1, a comparative fastening structure will be described, which uses a fastened member 41 having an insertion hole 42 in which the above-mentioned protrusion 17 is not formed.

[0042] Fig. 7 is a top view showing a fastening structure of a comparative example in which a fastened member 11 is fastened to a fastened member 41 having an insertion hole 42 without a protrusion 17. Fig. 8 is a cross-sectional view taken along line VIII-VIII in Fig. 7. Fig. 7 shows the fastening structure of the comparative example as viewed from the fastened member 41 side.

[0043] The insertion hole 42 is a cylindrical through-hole that penetrates the fastened member 41 in the thickness direction of the fastened member 41. That is, the opening shape of the insertion hole 42 in the in-plane direction of the fastened member 41 is circular. The insertion hole 42 is not female-threaded, and no thread groove is formed on the inner peripheral surface 42b of the insertion hole 42.

[0044] In the fastening structure of the comparative example shown in FIG. 7 and FIG. 8, the shaft portion 22 of the fixing screw 20 is in contact with the fastened member in the vertical direction. 41 side into insertion hole 42, and then screwed into inner circumferential surface 13b of cylindrical protrusion 13 of fastening member 11. When shank 22 of fixing screw 20 is screwed into inner circumferential surface 13b of cylindrical protrusion 13, a force in a direction toward fastening member 11, i.e., a downward force, acts on fastened member 41. Meanwhile, a force in a direction toward fastened member 41, i.e., an upward force, acts on cylindrical protrusion 13 of fastening member 11. In other words, a force pressing fastening member 11 and fastened member 41 against each other acts on each other, and fixing screw 20 is fastened.

[0045] 7 and 8, when a fastened member 41 having an insertion hole 42 without a protrusion toward the inside is formed and a fastening member 11 are fastened with a fixing screw 20, if the plate thickness of the fastening member 11 is thin, the cylindrical protrusion 13 is deformed toward the fastened member 41 by a force acting toward the fastened member 41 as the fixing screw 20 is screwed in. At this time, if there is a large difference between an inner diameter 42a of the insertion hole 42 of the fastened member 41 and an inner diameter 13a of the cylindrical protrusion 13 of the fastening member 11, a large moment acts on the entire inner circumferential surface 13b of the cylindrical protrusion 13 in a direction toward the fastened member 41 with the position of the inner circumferential surface of the insertion hole 42 in the in-plane direction of the fastened member 41 as a fulcrum. In other words, in an upward direction with the position of the inner circumferential surface of the insertion hole 42 in the in-plane direction of the fastened member 41 as a fulcrum.

[0046] As a result, the cylindrical protrusion 13 is significantly deformed in the direction toward the fastened member 41 and enters the space around the incomplete thread portion 22b of the fixing screw 20, causing the fixing screw 20 to spin freely, which may make it impossible to fasten the fastened member 41 and the fastening member 11. The portion around the incomplete thread portion 22b is the space inside the insertion hole 42, between the inner circumferential surface of the insertion hole 42 and the outer circumferential surface of the incomplete thread portion 22b.

[0047] That is, a fastened member 41 having an insertion hole 42 larger than the outer diameter of the cylindrical protrusion 13 is placed on the fastening member 11, and the fixing screw 20 passing through the insertion hole 42 is tightened from the fastened member 41 side. If there is a large difference between the inner diameter 42a of the insertion hole 42 of the fastened member 41 and the inner diameter 13a of the cylindrical protrusion 13 of the fastening member 11, the metal sheet around the cylindrical protrusion 13 is plastically deformed toward the screw head 21 of the fixing screw 20. That is, the cylindrical protrusion 13 is drawn into the insertion hole 42 as the fixing screw 20 is tightened, resulting in a so-called jacking up phenomenon.

[0048] In contrast, in the fastening structure 100 according to the first embodiment, as shown in Figures 1, 2, 3, 5 and 6, the fastened member 12 having a plurality of protrusions 17 on the inner peripheral surface of the insertion hole 14, which protrude in a direction toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12, is fastened to the fastening member 11. When the fastened member 12 having the plurality of protrusions 17 on the inner peripheral surface of the insertion hole 14 and the fastening member 11 are fastened to each other with the fixing screw 20 in this manner, it is possible to reduce the difference between the opening width of the insertion hole 14 of the fastened member 12 and the inner diameter 13a of the cylindrical protrusion 13 of the fastening member 11 at the portion of the plurality of protrusions 17 formed on the inner peripheral surface of the insertion hole 14 of the fastened member 12.

[0049] Specifically, in the fastening structure 100, when the fastened member 12 and the fastening member 11 are fastened together by the fixing screw 20, the gap between the inner circumferential surface of the insertion hole 14 of the fastened member 12 and the outer circumferential surface of the incomplete thread portion 22b in the in-plane direction of the fastened member 12 can be made small at the portion of the multiple protrusions 17. Therefore, in the fastening structure 100, even when the plate thickness of the fastening member 11 is thinner than the plate thickness of the fastened member 12 as shown in Figures 5 and 6, the moment acting on the entire inner circumferential surface 13b of the cylindrical protrusion 13 toward the fastened member 12 can be attenuated with the position of the inner circumferential surface of the insertion hole 14 in the in-plane direction of the fastened member 12 as a fulcrum.

[0050] As a result, in the fastening structure 100, when the fastened member 12 and the fastening member 11 are fastened together with the fixing screw 20, the cylindrical protrusion 13 can be prevented from significantly deforming in the direction toward the fastened member 12 and entering the space between the inner circumferential surface of the insertion hole 14 and the outer circumferential surface of the incomplete thread portion 22b. As a result, in the fastening structure 100, it is possible to prevent the fixing screw 20 from spinning freely due to the occurrence of the so-called jack-up phenomenon of the cylindrical protrusion 13, and the fastened member 12 and the fastening member 11 can be reliably fastened together with the fixing screw 20.

[0051] That is, in the fastening structure 100, it is possible to attenuate the large moment that acts on the entire inner circumferential surface 13b of the cylindrical protrusion 13 in the direction toward the fastened member 41 in the case of the fastening structure of the comparative example described above, and it is possible to suppress deformation of the cylindrical protrusion 13 in the direction toward the fastened member 12. As a result, in the fastening structure 100, it is possible to fasten the fastened member 12 and the fastening member 11 together without the cylindrical protrusion 13 penetrating into the area around the incomplete thread portion 22b of the fixing screw 20 and deforming it.

[0052] Therefore, in the fastening structure 100, the above-mentioned effect can be obtained as long as a plurality of protrusions 17 are formed that protrude even slightly in a direction toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12. In this case, the bearing diameter of the screw head 21, the diameter of the first imaginary circle 15, the diameter of the second imaginary circle 16, and the inner diameter 13a of the cylindrical protrusion 13 satisfy the relationship "bearing diameter of the screw head 21>diameter of the first imaginary circle 15>diameter of the second imaginary circle 16>inner diameter 13a of the cylindrical protrusion 13." In the fastening structure 100, the above-mentioned effect can be obtained by satisfying this relationship.

[0053] Here, the first width 14a of the insertion hole 14 is the opening width of the insertion hole 14, which is the narrowest width of the insertion hole 14 in the in-plane direction of the fastened member 12 as shown in Fig. 1, and is the narrowest width among the widths between the protrusions 17 facing each other across the central axis 14c of the insertion hole 14. Therefore, the first width 14a can be said to be the minimum width of the insertion hole 14. In the first pattern of insertion holes 14 shown in Figs. 1 and 2, the first width 14a corresponds to the diameter of the second imaginary circle 16.

[0054] 1 and 2, the second width 14b of the insertion hole 14 is the opening width of the insertion hole 14, which is the widest width of the insertion hole 14 in the in-plane direction of the fastened member 12, and is the width of the insertion hole 14 at a position where the protrusions 17 do not face each other. Therefore, the second width 14b can be said to be the maximum width of the insertion hole 14. In the first pattern of insertion holes 14 shown in FIGS. 1 and 2, the second width 14b corresponds to the diameter of the first imaginary circle 15.

[0055] In the fastening structure 100, the plate thickness of the fastened member 12 is equal to or less than the length of the incomplete thread portion 22b of the fixing screw 20. As described above, the incomplete thread portion 22b is a portion immediately below the screw head 21, that is, a portion of the shank 22 adjacent to the screw head 21, where the thread 23 is not formed. The length of the incomplete thread portion 22b is the length of the incomplete thread portion 22b in the axial direction of the central axis of the cylindrical shank 22 extending from the screw head 21 in the fixing screw 20. The length of the incomplete thread portion 22b is the distance from the bottom surface of the screw head 21 to the first thread 23 on the screw head 21 side of the shank 22 in the axial direction of the central axis of the shank 22. The bottom surface of the screw head 21 can be said to be the seat surface of the screw head 21. The axial direction of the central axis of the cylindrical shank 22 can be said to be the plate thickness direction of the fastened member 12.

[0056] If the fixing screw 20 does not have the incomplete thread portion 22b, the thread 23 is always engaged with the inner peripheral surface 13b of the cylindrical protrusion 13 of the fastening member 11. Even if the cylindrical protrusion 13 is pulled into the insertion hole 14 when the fixing screw 20 is completely tightened, the cylindrical protrusion 13 still engages with all of the threads 23 in the axial direction of the central axis of the shaft portion 22 of the fixing screw 20, including the threads 23 located in the region inside the insertion hole 14. For this reason, the fixing screw 20 does not spin freely.

[0057] On the other hand, a normal fixing screw has an incomplete thread portion 22b like the fixing screw 20. If the length of the incomplete thread portion 22b is longer than the plate thickness of the fastened member 12, the entire cylindrical protrusion 13 of the fastening member 11 will be pulled into the insertion hole 14 when the fixing screw 20 is tightened. The cylindrical protrusion 13 pulled into the insertion hole 14 will be located in a region of the insertion hole 14 facing the incomplete thread portion 22b in the axial direction of the central axis of the shaft portion 22, and the fixing screw 20 will spin freely.

[0058] However, in the fastening structure 100, as described above, it is possible to prevent the fixing screw 20 from spinning freely due to the occurrence of the so-called jack-up phenomenon of the cylindrical protrusion 13, and the fastened member 12 and the fastening member 11 can be securely fastened by the fixing screw 20.

[0059] In the fastening structure 100, it is also possible to fasten the fastened member 12 and the fastening member 11 with a washer sandwiched between the seat surface of the screw head 21 of the fixing screw 20 and the fastened member 12. Even when the fastened member 12 and the fastening member 11 are fastened using a washer as described above, and the sum of the plate thickness of the washer and the plate thickness of the fastened member 12 is equal to or less than the length of the incomplete thread portion 22b of the fixing screw 20, the above-mentioned effect can be obtained.

[0060] That is, the "plate thickness of the fastened member 12" in the above-mentioned condition that "the plate thickness of the fastened member 12 is equal to or less than the length of the incomplete thread portion 22b of the fixing screw 20" includes "the sum of the plate thickness of the washer and the plate thickness of the fastened member 12" in the case where the fastened member 12 and the fastening member 11 are fastened using a washer in addition to the fixing screw 20. Even in this case, as described above, the fastening structure 100 can prevent the fixing screw 20 from spinning freely due to the occurrence of the so-called jack-up phenomenon of the cylindrical protrusion 13, and the fastened member 12 and the fastening member 11 can be reliably fastened by the fixing screw 20.

[0061] Furthermore, when a fastened member having an insertion hole and a fastening member having a cylindrical protrusion are overlapped and fastened with a fixing screw, if the inner diameter of the insertion hole is smaller than the inner diameter of the cylindrical protrusion, the fixing screw will not enter the insertion hole and the fastened member and the fastening member cannot be fastened together. For this reason, the inner diameter of the insertion hole of the fastened member is made larger than the inner diameter of the cylindrical protrusion.

[0062] Therefore, in the fastening structure 100, the relationship among the bearing diameter of the screw head 21, the diameter of the first virtual circle 15, the diameter of the second virtual circle 16, and the inner diameter 13a of the cylindrical protrusion 13 is "bearing diameter of the screw head 21 > diameter of the first virtual circle 15 > diameter of the second virtual circle 16 > inner diameter 13a of the cylindrical protrusion 13."

[0063] Here, in the fastening structure 100, it is possible to simply reduce the diameter of the insertion hole 14 to the inner diameter 13a of the cylindrical protrusion 13. However, if the diameter of the insertion hole 14 is reduced to the inner diameter 13a of the cylindrical protrusion 13, the workability of tightening the fixing screw 20 deteriorates due to misalignment between the insertion hole 14 and the cylindrical protrusion 13 when the fastening member 11 and the fastened member 12 are overlapped.

[0064] That is, if the diameter of the insertion hole 14 is reduced to the size of the inner diameter 13a of the cylindrical protrusion 13, and the positional relationship between the insertion hole 14 and the cylindrical protrusion 13 in the in-plane direction of the fastening member 11 and the fastened member 12 does not become a predetermined positional relationship due to manufacturing variations in the fastening member 11 and the fastened member 12, causing a misalignment between the insertion hole 14 and the cylindrical protrusion 13, the workability of tightening the fixing screw 20 deteriorates. Examples of manufacturing variations between the fastening member 11 and the fastened member 12 include distortion of the metal sheet constituting the fastening member 11, or distortion of the metal sheet constituting the fastened member 12.

[0065] Therefore, in the fastening structure 100, the diameter of the insertion hole 14 is not simply reduced to the inner diameter 13a of the cylindrical protrusion 13, but a plurality of protrusions 17 protruding in a direction toward the inside of the insertion hole 14 are provided on the inner peripheral surface of the insertion hole 14. As a result, in the fastening structure 100, even if the insertion hole 14 and the cylindrical protrusion 13 are misaligned due to manufacturing variations in the fastening member 11 and the fastened member 12, the fastening member 11 can have an improved resistance to being pulled into the insertion hole 14 by screw fastening without deteriorating the workability of tightening the fixing screw 20. The resistance to being pulled into the insertion hole 14 by screw fastening of the fastening member 11 acts to suppress or prevent the cylindrical protrusion 13 from being pulled into the insertion hole 14 when the fixing screw 20 is tightened.

[0066] The fastening structure 100 according to the first embodiment is not limited to the above structure, and can be appropriately modified without departing from the gist of the structure of the fastening structure 100. In the fastening structure 100, the number of the first circumferential points 15P existing on the circumference of the first imaginary circle 15 and the number of the second circumferential points 16P existing on the circumference of the second imaginary circle 16 are not limited. That is, in the fastening structure 100, the number of bending points, which are points where the opening shape of the insertion hole 14 is bent in the in-plane direction of the fastened member 12, is not limited.

[0067] However, it is necessary to provide two or more protrusions 17 on the inner peripheral surface of the insertion hole 14, and more preferably, three or more protrusions 17 are provided. The reason why two or more protrusions 17 are required on the inner peripheral surface of the insertion hole 14 is to support the fixing screw 20 by the protrusions 17 so that the fixing screw 20 is not biased inside the insertion hole 14 in the in-plane direction of the fastened member 12, thereby reducing the difference between the opening dimension of the insertion hole 14 of the fastened member 12 and the inner diameter 13a of the cylindrical protrusion 13 of the fastening member 11. If the fixing screw 20 is biased inside the insertion hole 14 in the in-plane direction of the fastened member 12, the effect of reducing the gap between the inner peripheral surface of the insertion hole 14 of the fastened member 12 and the outer peripheral surface of the incomplete thread portion 22b in the in-plane direction of the fastened member 12 may be insufficient.

[0068] That is, by providing two or more protrusions 17 on the inner peripheral surface of the insertion hole 14, the position of the central axis of the fixing screw 20 inside the insertion hole 14 does not deviate from the position of the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12, and the fixing screw 20 is supported by the protrusions 17, thereby making it possible to reduce the difference between the opening dimension of the insertion hole 14 in the fastened member 12 and the inner diameter 13a of the cylindrical protrusion 13 of the fastening member 11. Furthermore, by providing three or more protrusions 17 on the inner peripheral surface of the insertion hole 14, the above effect can be obtained more reliably.

[0069] Furthermore, the type of the connection line connecting the first circumferential point 15P and the second circumferential point 16P in the opening shape of the insertion hole 14 may be a curved line or a straight line, and includes lines of various shapes that can connect the first circumferential point 15P and the second circumferential point 16P to form the opening shape of the insertion hole 14. Furthermore, the way in which the first circumferential point 15P and the second circumferential point 16P are connected may be regular or irregular.

[0070] Therefore, the opening shape of the insertion hole 14 in the in-plane direction of the fastened member 12 may be symmetrical or asymmetrical. That is, the opening shape of the insertion hole 14 in the in-plane direction of the fastened member 12 may be point-symmetrical with respect to the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12, or may be asymmetrical with respect to the central axis 14c of the insertion hole 14. In addition, the protrusions 17 may have the same protrusion shape or size from the inner peripheral surface of the insertion hole 14 all over the entire circumference of the opening shape of the insertion hole 14, may be different all over the entire circumference of the opening shape of the insertion hole 14, or may be partially the same all over the entire circumference of the opening shape of the insertion hole 14. In addition, the protrusions 17 may have an R-shaped tip protruding from the inner peripheral surface of the insertion hole 14, or may have a shape with a chamfered portion.

[0071] 9 to 19 are top views showing second to twelfth patterns of the opening shape of the insertion hole 14 of the fastened member 12 in the fastening structure 100 according to the first embodiment, respectively.

[0072] The opening shape of the insertion hole 14 of the second pattern shown in Figure 9 has an asymmetric shape in which a plurality of first circumferential points 15P, which are points located on the circumference of the first virtual circle 15, and a plurality of second circumferential points 16P, which are points located on the circumference of the second virtual circle 16, are continuously and alternately connected by straight lines around the entire circumference of each virtual circle.

[0073] The opening shape of the insertion hole 14 of the third pattern shown in Figure 10 has an asymmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves around the entire circumference of each imaginary circle.

[0074] The opening shape of the insertion hole 14 of the fourth pattern shown in Figure 11 has an asymmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves around the entire circumference of each imaginary circle.

[0075] The opening shape of the insertion hole 14 of the fifth pattern shown in Figure 12 has an asymmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curved lines or straight lines around the entire circumference of each imaginary circle.

[0076] The opening shape of the insertion hole 14 of the sixth pattern shown in Figure 13 has an asymmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves or straight lines around the entire circumference of each imaginary circle.

[0077] The opening shape of the insertion hole 14 of the seventh pattern shown in Figure 14 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curved lines or straight lines around the entire circumference of each imaginary circle.

[0078] The opening shape of the insertion hole 14 of the eighth pattern shown in Figure 15 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves around the entire circumference of each imaginary circle.

[0079] The opening shape of the insertion hole 14 of the 9th pattern shown in Figure 16 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves or straight lines around the entire circumference of each imaginary circle.

[0080] The opening shape of the insertion hole 14 of the 10th pattern shown in Figure 17 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by straight lines around the entire circumference of each imaginary circle.

[0081] The opening shape of the insertion hole 14 of the 11th pattern shown in Figure 18 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves around the entire circumference of each imaginary circle.

[0082] The opening shape of the insertion hole 14 of the 12th pattern shown in Figure 19 has a point-symmetric shape in which a plurality of first circumferential points 15P and a plurality of second circumferential points 16P are continuously and alternately connected by curves or straight lines around the entire circumference of each imaginary circle.

[0083] Fig. 20 is a top view showing a first example of a state in which the centers of the cylindrical protrusion 13 of the fastening member 11 and the insertion hole 14 of the fastened member 12 are misaligned when the fastening member 11 and the fastened member 12 are overlapped. Fig. 21 is a top view showing a second example of a state in which the centers of the cylindrical protrusion 13 of the fastening member 11 and the insertion hole 14 of the fastened member 12 are misaligned when the fastening member 11 and the fastened member 12 are overlapped. Figs. 20 and 21 show a state in which the fastening member 11 and the fastened member 12 are overlapped in a predetermined positional relationship in the in-plane direction of the fastening member 11 and the fastened member 12. In other words, Figures 20 and 21 show a state in which the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12, which should originally overlap in the in-plane direction of the fastening member 11 and the fastened member 12, are misaligned due to manufacturing variations between the fastening member 11 and the fastened member 12.

[0084] 20, the direction of misalignment between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction of the fastened member 12 is parallel to the width direction of the first width 14a of the insertion hole 14. That is, in the first example shown in FIG. 20, the central axis 13c and the central axis 14c in the in-plane direction of the fastened member 12 are misaligned in a direction parallel to the width direction of the first width 14a of the insertion hole 14.

[0085] 21, the direction of misalignment between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction of the fastened member 12 is parallel to the width direction of the second width 14b of the insertion hole 14. That is, in the second example shown in FIG. 21, the central axis 13c and the central axis 14c in the in-plane direction of the fastened member 12 are misaligned in a direction parallel to the width direction of the second width 14b of the insertion hole 14.

[0086] 20, when fastening member 11 and fastened member 12 are fastened with fixing screw 20, it is first necessary to reduce the positional deviation between central axis 13c of cylindrical protrusion 13 of fastening member 11 and central axis 14c of insertion hole 14 of fastened member 12 in the in-plane direction of fastening member 11 and fastened member 12. In other words, it is necessary to position fastening member 11 and fastened member 12 by changing the positional relationship between fastening member 11 and fastened member 12 so as to reduce the positional deviation between central axis 13c and central axis 14c in the in-plane direction of fastening member 11 and fastened member 12.

[0087] 20, if the central axes 13c and 14c in the in-plane direction of the fastened member 12 are misaligned in a direction parallel to the direction of the first width 14a of the insertion hole 14, the likelihood of positioning the fastening member 11 and the fastened member 12 is reduced. In other words, if the central axes 13c and 14c in the in-plane direction of the fastened member 12 are misaligned in a direction parallel to the direction of the first width 14a of the insertion hole 14, when changing the positional relationship between the fastening member 11 and the fastened member 12 in the in-plane direction of the fastened member 12, it may not be possible to position the fastening member 11 and the fastened member 12 to reduce the misalignment between the positions of the central axes 13c and 14c due to other constraints on the alignment of the fastening member 11 and the fastened member 12.

[0088] For this reason, when the positional deviation direction between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction of the fastened member 12 can be predicted in advance, it is preferable to form the cylindrical protrusion 13 of the fastening member 11 and the insertion hole 14 of the fastened member 12 so that the positional deviation direction between the central axis 13c and the central axis 14c in the in-plane direction of the fastened member 12 is parallel to the width direction of the second width 14b of the insertion hole 14, as shown in Figure 21. This makes it possible to increase the likelihood of positioning the fastening member 11 and the fastened member 12 when positioning them.

[0089] In other words, when changing the positional relationship between the fastening member 11 and the fastened member 12 in the in-plane direction of the fastened member 12, it is possible to increase the probability of being able to position the fastening member 11 and the fastened member 12 to reduce the positional misalignment between the position of the central axis 13c and the position of the central axis 14c, including other constraints on the alignment of the fastening member 11 and the fastened member 12.

[0090] In this case, the second width 14b of the insertion hole 14 can be formed by forming the opening shape of the insertion hole 14 in the in-plane direction of the fastened members 12 to be point-symmetrical with respect to the central axis 14c of the insertion hole 14, and the direction of positional deviation between the central axis 13c and the central axis 14c in the in-plane direction of the fastened members 12 can be made parallel to the direction of the second width 14b of the insertion hole 14. Note that it does not matter whether the opening shape of the insertion hole 14 here is line-symmetrical with respect to a virtual line passing through the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened members 12.

[0091] Fig. 22 is a top view showing a third example of a state in which the centers of the cylindrical protrusion 13 of the fastening member 11 and the insertion hole 14 of the fastened member 12 are misaligned when the fastening member 11 and the fastened member 12 are overlapped. Fig. 23 is a top view showing a fourth example of a state in which the centers of the cylindrical protrusion 13 of the fastening member 11 and the insertion hole 14 of the fastened member 12 are misaligned when the fastening member 11 and the fastened member 12 are overlapped. Figs. 22 and 23 show a state in which the fastening member 11 and the fastened member 12 are overlapped in a predetermined positional relationship in the in-plane direction of the fastening member 11 and the fastened member 12. In other words, Figures 22 and 23 show a state in which the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12, which should originally overlap in the in-plane direction of the fastening member 11 and the fastened member 12, are misaligned due to manufacturing variations between the fastening member 11 and the fastened member 12.

[0092] 22, the direction of misalignment between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction of the fastened member 12 is parallel to the direction of the third width 14d of the insertion hole 14. That is, in the third example shown in FIG. 22, the central axis 13c and the central axis 14c in the in-plane direction of the fastened member 12 are misaligned in a direction parallel to the direction of the third width 14d of the insertion hole 14.

[0093] The third width 14d of the insertion hole 14 is the opening width of the insertion hole 14, and is the width between a first circumferential point 15P, which is a point located on the circumference of the first imaginary circle 15, and a second circumferential point 16P, which is a point located on the circumference of the second imaginary circle 16, which are opposed to each other via the central axis 14c of the insertion hole 14 in the fastened member 12 in the in-plane direction of the fastened member 12 as shown in Figure 22.

[0094] 23, the direction of misalignment between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction to the fastened member 12 is parallel to the direction of the third width 14d of the insertion hole 14. That is, in the fourth example shown in FIG. 23, the central axis 13c and the central axis 14c in the in-plane direction to the fastened member 12 are misaligned in the direction parallel to the direction of the third width 14d of the insertion hole 14.

[0095] Therefore, the opening shape of the insertion hole 14 in the third example shown in Fig. 22 is asymmetrical about a point with respect to the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12. And the opening shape of the insertion hole 14 in the fourth example shown in Fig. 23 is also asymmetrical about a point with respect to the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12.

[0096] In cases where the direction of positional deviation between the central axis 13c of the cylindrical protrusion 13 of the fastening member 11 and the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12 cannot be predicted in advance, the opening shape of the insertion hole 14 is made asymmetrical with respect to the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12, as shown in Figures 22 and 23.

[0097] This makes it possible to always set the distance between a first circumferential point 15P, which is a point on the insertion hole 14, and a second circumferential point 16P, which is a point on the insertion hole 14 that face each other across the central axis 14c of the insertion hole 14 of the fastened member 12 in the in-plane direction of the fastened member 12, to the same dimension for all of the first circumferential points 15P and second circumferential points 16P of the insertion hole 14. In other words, the third width 14d of the insertion hole 14 can be set to the same length for all of the first circumferential points 15P and second circumferential points 16P of the insertion hole 14, and it is possible to ensure that the third width 14d is larger than the first width 14a of the insertion hole 14 in any direction of the third width 14d.

[0098] Therefore, when positioning the fastening member 11 and the fastened member 12 to reduce the positional deviation between the position of the central axis 13c and the position of the central axis 14c in the in-plane direction of the fastening member 11 and the fastened member 12, the degree of freedom in the movement direction of the fastening member 11 or the fastened member 12 increases, and the positioning operation of the fastening member 11 and the fastened member 12 can be performed stably and easily. Note that the opening shape of the insertion hole 14 here does not matter whether it is line-symmetrical with respect to a virtual line passing through the central axis 14c of the insertion hole 14 in the in-plane direction of the fastened member 12.

[0099] As described above, in the fastening structure 100 according to the first embodiment, the fastened member 12, which has a plurality of projections 17 on the inner circumferential surface of the insertion hole 14 that protrude in a direction toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12, and the fastening member 11 are fastened together by the fixing screw 20. Therefore, in the fastening structure 100, when the fastened member 12 and the fastening member 11, which are multiple components, are fastened together by the fixing screw 20, it is possible to reduce the gap between the inner circumferential surface of the insertion hole 14 of the fastened member 12 and the outer circumferential surface of the incomplete thread portion 22b in the in-plane direction of the fastened member 12.

[0100] As a result, in the fastening structure 100, when the fastened member 12 and the fastening member 11, which are multiple components, are fastened together with the fixing screw 20, the cylindrical protrusion 13 can be prevented from significantly deforming in the direction toward the fastened member 12 and entering the space between the inner circumferential surface of the insertion hole 14 and the outer circumferential surface of the incomplete thread portion 22b. Therefore, in the fastening structure 100, it is possible to prevent the fixing screw 20 from spinning freely due to the occurrence of the so-called jack-up phenomenon of the cylindrical protrusion 13, and the fastened member 12 and the fastening member 11 can be reliably fastened together with the fixing screw 20.

[0101] Furthermore, in the fastening member 11, other than the processing for forming the cylindrical protrusion 13, no other processing such as drawing is required to form a dedicated component for fixing the fastened member 11 to the fastened member 12, and there is no increase in manufacturing costs due to such other processing.

[0102] Furthermore, in the fastened member 12, the protrusion 17 is formed in the insertion hole 14, but the protrusion 17 can be easily formed integrally with the insertion hole 14 in one step when the insertion hole 14 is formed. Therefore, in manufacturing the fastening structure 100, the formation of the protrusion 17 does not complicate the processing, the number of steps required for processing and the processing time do not increase, and the formation of the protrusion 17 does not increase the manufacturing cost.

[0103] In the above, the fixing screw 20 is described as a self-tapping screw, but the fixing screw 20 is not limited to a self-tapping screw and may be a normal screw. A normal screw is also composed of a screw head and a shank, like the fixing screw 20 of the self-tapping screw described above. The shank has a cylindrical shape and has a screw thread. The shank also has a complete thread portion in which a complete screw thread is formed, and an incomplete screw portion in which an incomplete screw thread is formed. In this case, the cylindrical protrusion 13 may be a female thread.

[0104] Also, the fastening member 11 may not be formed with the cylindrical protrusion 13. That is, instead of the cylindrical protrusion 13, the fastening member 11 may be formed with an insertion hole through which the fixing screw 20 is inserted, penetrating the fastening member 11 in the thickness direction of the fastening member 11. In this case, a self-tapping screw is used for the fastening screw 20, and the insertion hole of the fastening member 11 is a pilot hole without a thread groove. Also, the cylindrical protrusion 13 may not be formed, and a normal screw may be used for the fastening screw 20, and the insertion hole of the fastening member 11 may be a female thread. In this way, the hole through which the fixing screw 20 is inserted in the fastening member 11 may be a female thread or a pilot hole, and the female thread or the pilot hole may be a cylindrical protrusion. Also, the shape of the screw head 21 of the fastening screw 20 is not important.

[0105] That is, the same effect as that of the fastening structure 100 can be obtained even in a configuration in which a fastened member 12 having a plurality of protrusions 17 on the inner peripheral surface of the insertion hole 14 that protrude in a direction toward the inside of the insertion hole 14 in the in-plane direction of the fastened member 12 and a thin fastening member having no cylindrical protrusion 13 and having an insertion hole through which the fixing screw 20 is inserted is fastened by the fixing screw 20. That is, even in such a fastening structure, by providing a plurality of protrusions 17 on the inner peripheral surface of the insertion hole 14, it is possible to prevent the fixing screw 20 from spinning freely due to the portion of the thin fastening member surrounding the insertion hole being drawn into the insertion hole 14 of the fastened member 12.

[0106] Therefore, in the first embodiment, a fastening structure is realized which includes a fastening member 11 having a female thread or a pilot hole formed therein, a fastened member 12 which is arranged in a stacked manner on the fastening member 11 and has an insertion hole 14 formed therein that is larger than the diameter of the female thread and the diameter of the pilot hole, and a fixing screw 20 which passes through the insertion hole 14 from the fastened member 12 side and fits into a thread groove on the inner circumferential surface of the female thread or the pilot hole to fix the fastening member 11 and the fastened member 12, and the insertion hole 14 has a plurality of protrusions 17 which protrude in a direction toward the center of the insertion hole 14 in the in-plane direction of the fastened member 12. A fastening structure having this configuration can obtain the effects of the fastening structure 100 described above.

[0107] Here, when the fastening member 11 is formed with a cylindrical protrusion 13 and the female thread or pilot hole is the cylindrical protrusion 13, the fastened member 12 is formed with an insertion hole 14 larger than the inner diameter of the female thread and the inner diameter of the pilot hole. On the other hand, when the fastening member 11 is not formed with a cylindrical protrusion 13 and the fastening member 11 is formed with a female thread or pilot hole, the fastened member 12 is formed with an insertion hole 14 larger than the diameter of the female thread and the diameter of the pilot hole.

[0108] In addition, when a cylindrical protrusion 13 is formed on the fastening member 11 and the female thread or pilot hole is the cylindrical protrusion 13, the insertion hole 14 is formed in the in-plane direction of the fastened member 12 between a first imaginary circle 15 that is coaxial with the central axis of the female thread or pilot hole and has a diameter larger than the inner diameter of the female thread and the inner diameter of the pilot hole, and a second imaginary circle 16 that is coaxial with the central axis 14c of the insertion hole 14, has a diameter larger than the inner diameter of the female thread and the inner diameter of the pilot hole and is smaller than the first imaginary circle 15.

[0109] In addition, when the fastening member 11 does not have a cylindrical protrusion 13 but has a female thread or a pilot hole formed therein, the insertion hole 14 is formed in the in-plane direction of the fastened member 12 between a first imaginary circle 15 which is coaxial with the central axis of the female thread or pilot hole and has a diameter larger than the diameter of the female thread and the diameter of the pilot hole, and a second imaginary circle 16 which is coaxial with the central axis 14c of the insertion hole 14, has a diameter larger than the diameter of the female thread and the diameter of the pilot hole and is smaller than the first imaginary circle 15.

[0110] In the fastening structure 100 according to the first embodiment, the metal sheets to be fastened are two metal sheets, the fastening member 11 and the fastened member 12, but the number of metal sheets to be fastened may be more than two. For example, another metal sheet having an insertion hole through which the fixing screw 20 is inserted may be provided between the fastening member 11 and the fastened member 12.

[0111] Furthermore, the fastened members 12 are not limited to metal sheet metal, and may be plate members made of materials other than metal, such as resin. Also, between the fastening member 11 and the fastened members 12, a plate member made of materials other than metal, such as resin, in which an insertion hole through which the fixing screw 20 is inserted may be provided.

[0112] The fastening member 11 is a metal sheet made of a metallic material and has a thickness of less than 0.8 mm. In the fastening structure 100 according to the first embodiment, when the fastening member 11 made of a metal sheet is particularly thin, that is, less than 0.8 mm, the effect of the fastening structure 100 according to the first embodiment described above, that is, the fastening member 11 and the fastened member 12 can be reliably fixed by the fixing screw 20, becomes particularly effective.

[0113] As described above, according to the fastening structure 100 of the first embodiment, when the fastening member 11 and the fastened member 12 are stacked on each other, the fastening member 11 is fastened by tightening the fixing screw 20, which is a male screw, from the fastened member 12 side, and the cylindrical protrusion 13 of the fastening member 11 is pulled into the insertion hole 14 of the fastened member 12 as the fixing screw 20 is tightened. This suppresses free rotation of the fixing screw 20, thereby fastening the fastening member and the fastened member. of This provides a fastening structure that is easy to manufacture.

[0114] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies. Parts of the configurations may be omitted or modified without departing from the spirit of the invention.

[0115] Various aspects of the present disclosure are summarized below as appendices.

[0116] (Appendix 1) A fastening member having a female thread or a pilot hole formed therein; a fastened member disposed on the fastening member and having an insertion hole formed therein that is larger than the diameter of the female screw and the diameter of the pilot hole; a fixing screw that is inserted through the insertion hole from the fastened member side and fits into the female screw or the thread groove on the inner peripheral surface of the pilot hole to fix the fastening member and the fastened member; Equipped with the insertion hole includes a plurality of protrusions protruding in an in-plane direction of the fastened member toward a center of the insertion hole; A fastening structure characterized by the above.

[0117] (Appendix 2) the insertion hole is formed in an in-plane direction of the fastened member between a first imaginary circle which is coaxial with a central axis of the female screw or the pilot hole and has a diameter larger than a diameter of the female screw and a diameter of the pilot hole, and a second imaginary circle which is coaxial with a central axis of the insertion hole, has a diameter larger than a diameter of the female screw and a diameter of the pilot hole and is smaller than a diameter of the first imaginary circle; 2. The fastening structure according to claim 1,

[0118] (Appendix 3) the insertion hole has a point-symmetric shape with respect to a center of the insertion hole in an in-plane direction of the fastened member; 3. The fastening structure according to claim 2,

[0119] (Appendix 4) the insertion hole has a non-point-symmetric shape with respect to a center of the insertion hole in an in-plane direction of the fastened member; 3. The fastening structure according to claim 2,

[0120] (Appendix 5) The female screw or the pilot hole is a cylindrical protrusion formed by plastically deforming the fastening member into a cylindrical shape; 5. The fastening structure according to claim 1,

[0121] (Appendix 6) The plate thickness of the fastened member is equal to or less than the length of the incomplete thread portion of the fixing screw; 6. The fastening structure according to any one of claims 1 to 5, [Explanation of symbols]

[0122] 11 fastening member, 12, 41 fastened member, 13 cylindrical protrusion, 13a, 42a inner diameter, 13b, 42b inner circumferential surface, 13c, 14c central axis, 13d opening, 13e thread groove, 14, 42 insertion hole, 14a first width, 14b second width, 14d third width, 15 first imaginary circle, 16 second imaginary circle, 15P first circumferential point, 16P second circumferential point, 17 protrusion, 20 fixing screw, 21 screw head, 22 shaft, 22a complete thread portion, 22b incomplete thread portion, 23 thread, 100 fastening structure.

Claims

1. A fastening member having a female thread or a pilot hole formed therein; a fastened member disposed on the fastening member and having an insertion hole formed therein that is larger than the diameter of the female screw and the diameter of the pilot hole; a fixing screw that is inserted through the insertion hole from the fastened member side and fits into the female thread or the thread groove on the inner peripheral surface of the pilot hole to fix the fastening member and the fastened member; Equipped with The insertion hole includes a plurality of protrusions protruding in an in-plane direction of the fastened member toward a center of the insertion hole, the insertion hole is formed, in an in-plane direction of the fastened member, between a first imaginary circle which is coaxial with a central axis of the female screw or the pilot hole and has a diameter larger than a diameter of the female screw and a diameter of the pilot hole, and a second imaginary circle which is coaxial with a central axis of the insertion hole, has a diameter larger than a diameter of the female screw and a diameter of the pilot hole and is smaller than a diameter of the first imaginary circle; A fastening structure characterized by the above.

2. the insertion hole has a point-symmetric shape with respect to a center of the insertion hole in an in-plane direction of the fastened member; The fastening structure according to claim 1 .

3. the insertion hole has a non-point-symmetric shape with respect to a center of the insertion hole in an in-plane direction of the fastened member; The fastening structure according to claim 1 .

4. The female screw or the pilot hole is a cylindrical protrusion formed by plastically deforming the fastening member into a cylindrical shape; The fastening structure according to any one of claims 1 to 3, characterized in that

5. The plate thickness of the fastened member is equal to or less than the length of the incomplete thread portion of the fixing screw; The fastening structure according to claim 1 .

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