Loosening prevention structure of nutless bolt

Abstract

To provide a loosening prevention structure of a nutless bolt which achieves loosening prevention of a fixing mechanism while fixing an object to be fixed without using a nut, makes a male screw of a bolt unlikely to be crushed, and achieves workability which is almost the same level as that of a nut fastening method.SOLUTION: A loosening prevention structure of a nutless bolt comprises: a bolt body including a plate receiving part, a plate holding part connected to the plate receiving part, a peripheral surface groove part connected to a tip of the plate holding part, and a male screw part having a vertical groove part connected to the tip of the peripheral surface groove part; a holding plate loosely fitted in the plate holding part; a spring member loosely fitted in the plate holding part and disposed facing the holding plate; a crimp annular body loosely fitted in the peripheral surface groove part and connected to the spring member; and a stopper member configured to restrict the crimp annular body from being removed from the peripheral surface groove part. An object to be fixed is configured to be fixed by means of a biasing force of the spring member with the plate receiving part and the crimp annular body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a loosening prevention structure for a nutless bolt that fixes an object to be fixed without using a nut.

Background Art

[0002] Conventionally, it has been known that nuts screwed onto bolts gradually loosen due to vibration, impact, or aging deterioration, resulting in accidents such as falling off the bolts. Also, in the conventional fastening structure between a bolt and a nut, there has been a problem that the thread of the male thread portion of the bolt is crushed unless the thread of the female thread portion of the nut is aligned with the thread of the male thread portion of the bolt and then tightened.

[0003] Therefore, various techniques for preventing loosening of nuts have been provided since ancient times. For example, Patent Document 1 discloses a screwing structure between nuts having two upper and lower nuts screwed onto a bolt, and having a threaded portion eccentric from the center of the bolt screw hole at the connection portion between the two upper and lower nuts, and realizing prevention of nut loosening by screwing the bolt so as to straddle the upper and lower nuts in a state where the two upper and lower nuts are screwed together.

[0004] Patent Document 2 discloses a loosening prevention structure for preventing loosening of a bolt by adsorbing a washer-shaped magnet member on the surface of an object to be fastened between the object to be fastened and the nut, externally fitting a U-shaped piece in cross-section that abuts and engages with the hexagonal surface of the nut in a state where the nut is attached to the bolt, and fixing both ends of the U-shaped piece to the washer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, since the anti-loosening structures of such various nuts involve special processing of bolts and nuts, the structure is complex and the manufacturing cost is high. Also, the method of fastening the nut becomes complicated by using special additional members for the nut tightening operation, resulting in problems such as a decrease in work efficiency. Further, since these anti-loosening structures are configured such that the male thread of the bolt is screwed with the female thread of the nut, the problem of the thread of the male thread of the bolt being crushed has not been solved at all.

[0007] The present invention has been made in view of the above problems, and aims to provide an anti-loosening structure for a nutless bolt that realizes anti-loosening of a fixing mechanism while fixing an object to be fixed without using a nut, completely solves the problem of the male thread of the bolt being crushed, and realizes workability that is not much different from the conventional method of fastening bolts and nuts.

Means for Solving the Problems

[0008] In this invention, a bolt body having a plate receiving portion, a plate holding portion continuously provided to the plate receiving portion, a circumferential surface groove portion continuously provided at the tip of the plate holding portion, and a male screw portion having a longitudinal groove portion continuously provided at the tip of the circumferential surface groove portion, a gripping plate loosely fitted to the plate holding portion, a spring member loosely fitted to the plate holding portion and disposed opposite to the gripping plate, a crimping annular body loosely fitted to the circumferential surface groove portion and continuously provided to the spring member, and a stopper member that regulates the crimping annular body from detaching from the circumferential surface groove portion.

[0009] Further, the crimping annular body has a release regulation protrusion on its outer peripheral surface, the stopper member has an engaging protrusion, and the release regulation protrusion and the engaging protrusion are engaged to regulate the crimping annular body from detaching from the circumferential surface groove portion.

Effects of the Invention

[0010] According to the first aspect of the present invention, a bolt body includes a plate receiving portion, a plate holding portion connected to the plate receiving portion, a circumferential groove portion connected to the tip of the plate holding portion, and a male screw portion having a longitudinal groove portion connected to the tip of the circumferential groove portion. A gripping plate is loosely fitted to the plate holding portion, a spring member is loosely fitted to the plate holding portion and disposed opposite to the gripping plate, a crimping annular body is loosely fitted to the circumferential groove portion and connected to the spring member, and a stopper member that restricts the crimping annular body from detaching from the circumferential groove portion. With this configuration, it is possible to prevent loosening of the nutless bolt while fixing the object to be fixed. In addition, since the crimping annular body is not fixed by screwing a male screw and a female screw as in the prior art, the problem of accidentally crushing the male screw of the bolt during screw tightening as in the prior art can be completely solved.

[0011] Further, by engaging the crimping annular body and the stopper member, it is possible to restrict the crimping annular body from detaching from the circumferential groove portion of the bolt body, and prevent the fixing force of the object to be fixed by the plate receiving portion of the bolt body and the crimping annular body from decreasing.

[0012] According to the second aspect of the present invention, a release restricting protrusion is provided on the outer peripheral surface of the crimping annular body, an engaging protrusion is provided on the stopper member, and by engaging the release restricting protrusion and the engaging protrusion, the crimping annular body is restricted from detaching from the circumferential groove portion. Therefore, the detachment of the crimping annular body from the circumferential groove portion can be easily restricted with a simple configuration that only engages the crimping annular body and the stopper member. Further, after the crimping annular body and the stopper member are engaged and integrated, the crimping annular body and the stopper member do not come off from the circumferential groove portion, and the force for clamping the object to be fixed can be maintained constant without loosening.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0014] The present invention regulates the engagement state between the bolt body 1 for fixing the object to be fixed 3 and the crimping annular body 5 by a stopper member 6, maintains the state in which the object to be fixed 3 is sandwiched between the bolt body 1 and the crimping annular body 5, and solves the problem that the nut fastened to the bolt, which occurs in the conventional fastening structure of a bolt and a nut, becomes loose. At the same time, by eliminating the nut, it solves the problem that the thread of the bolt fastened to the nut is crushed and the bolt cannot be reused.

[0015] The anti-loosening structure of the nutless bolt according to the present embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 is an exploded perspective view showing the overall appearance of the anti-loosening structure of the nutless bolt. FIG. 2 is a view showing the bolt body 1, where (a) is a perspective view and (b) is a front view thereof. FIG. 3 is a view showing the configuration of the spring member 4, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A, and (c) is a partially enlarged view of (b). FIG. 4 is a perspective view showing the crimping annular body 5. FIG. 5 is a view showing the stopper member 6, where (a) is a perspective view and (b) is a plan view. FIG. 6 is a view showing the mounting and rotating tool 7 used when fixing the object to be fixed 3 with the anti-loosening structure of the nutless bolt, where (a) is a perspective view and (b) is a plan view. FIG. 7 is a view showing the removal rotating tool 8 for releasing the engagement state between the crimping annular body 5 and the stopper member 6 of the anti-loosening structure of the nutless bolt, where (a) is a perspective view and (b) is a plan view. FIG. 8 is a view showing the engagement state between the crimping annular body 5 and the stopper member 6 of the anti-loosening structure of the nutless bolt, where (a) shows the state before engagement and (b) shows the state after engagement. In the present embodiment, the depth direction in FIG. 1 is defined as the front-rear direction, and the vertical direction and the left-right direction will be described as the vertical direction and the left-right direction as they are.

[0016] The anti-loosening structure of the nutless bolt according to this embodiment, as shown in FIG. 1, includes a bolt body 1 corresponding to a conventional bolt, a gripping plate 2 corresponding to a conventional washer, a spring member 4 corresponding to a conventional spring washer, a crimping annular body 5 corresponding to a conventional nut, and a stopper member 6 that regulates the release of the engagement state between the crimping annular body 5 and the bolt body 1. In the anti-loosening structure of the nutless bolt according to this embodiment, two objects to be fixed 3, 3 are fixed between the gripping plate 2 and the spring member 4.

[0017] As shown in FIGS. 2(a) and (b), the bolt body 1 has a plate receiving portion 11, a plate holding portion 12 continuously provided on the upper surface of the plate receiving portion 11, a circumferential groove portion 13 continuously provided at the tip of the plate holding portion 12, and a male screw portion 14 continuously provided at the tip of the circumferential groove portion 13.

[0018] The plate receiving portion 11 is formed at one end of the bolt body 1 and corresponds to a portion of the head of the bolt formed in a substantially hexagonal shape in plan view. The plate receiving portion 11 has a plate holding portion 12 continuously provided at a substantially central portion of the upper surface. Note that the shape of the plate receiving portion 11 is not limited to a hexagonal shape, and any head shape such as a shape with a partial modification to the hexagonal shape, a substantially square shape, or a substantially circular shape can be adopted.

[0019] The plate holding portion 12 extends from one surface of the plate receiving portion 11 toward the tip of the bolt body 1 and is a columnar portion formed in a substantially circular shape in a cross-sectional view. The plate holding portion 12 is formed with a radius shorter than the length of the straight line connecting the center of the plate receiving portion 11 and the apex of the plate receiving portion 11. That is, in a front view, the plate holding portion 12 is formed smaller than the plate receiving portion 11, and the plate receiving portion 11 is formed in a flange shape capable of supporting a member inserted through the plate holding portion 12. Further, the plate holding portion 12 is formed shorter than the total thickness obtained by inserting the gripping plate 2, the spring member 4 in a natural state, and the two fixed objects 3, 3, which will be described later, and adding up the thicknesses of the respective members. That is, when the gripping plate 2, the fixed objects 3, 3, and the spring member 4 are inserted through the plate holding portion 12, the plate holding portion 12 is formed to have a length such that the upper end portion of the spring member 4 is located above the upper end portion of the plate holding portion 12.

[0020] The circumferential surface groove portion 13 extends from the tip of the plate holding portion 12 toward the tip of the bolt body 1 and is a columnar portion formed in a substantially circular shape in a cross-sectional view. The circumferential surface groove portion 13 is formed with a smaller diameter than the plate holding portion 12.

[0021] The male screw portion 14 is a solid columnar portion provided at the tip of the bolt body 1. The male screw portion 14 is formed with substantially the same diameter as the plate holding portion 12. The male screw portion 14 has a thread portion 15 helically engraved on the circumferential surface and a longitudinal groove portion 16 formed in a concave shape by notching a part of the thread portion 15 in a planar shape.

[0022] As shown in Fig. 2(a), in the present embodiment, the longitudinal groove portion 16 is provided at three locations on the circumferential surface of the male screw portion 14. The longitudinal groove portion 16 is provided at regular intervals in the circumferential direction on the circumferential surface of the male screw portion 14. In the present embodiment, the longitudinal groove portion 16 is provided at intervals of approximately 120 degrees.

[0023] The bolt body 1 configured in this way inserts the object to be fixed 3 into the plate holding portion 12 and supports it with the plate receiving portion 11, and presses the object to be fixed 3 toward the plate receiving portion 11 by the biasing force of the spring member 4 generated by the spring member 4 inserted into the plate holding portion 12 and the crimping annular body 5 inserted into the circumferential groove portion 13, so that it can be fixed between the spring member 4 and the plate receiving portion 11.

[0024] The gripping plate 2 corresponds to a conventional washer. The gripping plate 2 is a member for preventing deformation and scratches of the object to be fixed 3 by expanding the contact area with the object to be fixed 3 and dispersing the seating surface pressure when fixing the object to be fixed 3. The gripping plate 2 is formed in a disc shape with a certain thickness. The gripping plate 2 is formed to have a larger diameter than the length of the straight line connecting the center of the plate receiving portion 11 and the apex of the plate receiving portion 11 in a plan view, and has an insertion hole portion 2a formed with a slightly larger diameter than the plate holding portion 12 at the central portion. The gripping plate 2 is provided between the plate receiving portion 11 and the object to be fixed 3 in a state of being inserted into the plate holding portion 12.

[0025] As shown in FIGS. 3(a), (b), and (c), the spring member 4 corresponds to a conventional spring washer and is provided above the gripping plate 2 via the object to be fixed 3. The spring member 4 has an upper gripping plate 41 that contacts the object to be fixed 3 and a disc spring 42 that is integrally formed with the upper gripping plate 41 with an adhesive or the like. The upper gripping plate 41 is formed in a substantially disc shape with a certain thickness, similar to the gripping plate 2, and has an insertion hole portion 41a through which the plate holding portion 12 can be inserted at a substantially central portion. The upper gripping plate 41 has a pressing portion 41b that protrudes upward on the upper surface. The pressing portion 41b is provided along the insertion hole portion 41a.

[0026] The dish spring 42 is formed in a substantially frustum - shaped cone with the top side having a smaller diameter than the bottom side when viewed from the front. The dish spring 42 has a hole portion 42a with substantially the same diameter as the insertion hole portion 41a of the upper gripping plate 41 at the central portion. The dish spring 42 is formed with the outer diameter of the lower side smaller than the outer diameter of the upper gripping plate 41. The dish spring 42 is in contact with the upper gripping plate 41 near the lower surface of the outer peripheral end, and is integrally formed with the upper gripping plate 41 by applying an adhesive or the like to the contact surface. In this embodiment, a configuration in which the upper gripping plate 41 has a pressing portion 41b is described, but the upper gripping plate 41 is not limited to such a structure, and may be formed in a substantially donut - shape with a flat upper surface and an insertion hole portion 41a formed at the central portion.

[0027] The crimping annular body 5 corresponds to a conventional nut. As shown in FIG. 4, the crimping annular body 5 is an annular member having an insertion hole portion 51 through which the male screw portion 14 of the bolt body 1 can be inserted, and is composed of an annular body main body 54. The thickness of the annular body main body 54 is formed to be slightly smaller than the thickness of the circumferential groove portion 13 of the bolt body 1. The annular body main body 54 has a locking protrusion 52 protruding from the inner peripheral surface of the insertion hole portion 51 toward the central portion, and a release restriction protrusion 53 protruding from the outer peripheral surface of the annular body main body 54 in a direction opposite to the locking protrusion 52, that is, in the radial direction away from the central portion. In this embodiment, the locking protrusion 52 and the release restriction protrusion 53 are provided at a certain distance apart in the circumferential direction of the annular body main body 54. That is, among the locking protrusions 52 provided on the annular body main body 54, adjacent locking protrusions 52 are provided at intervals of approximately 120 degrees in the circumferential direction of the annular body main body 54, and the release restriction protrusions 53 are also provided at intervals of approximately 120 degrees in the circumferential direction of the annular body main body 54. Note that the number of locking protrusions 52 and release restriction protrusions 53 only needs to be the same as the number of longitudinal groove portions 16 provided on the male screw portion 14 of the bolt body 1. For example, when four longitudinal groove portions 16 are provided, four locking protrusions 52 and four release restriction protrusions 53 are also provided.

[0028] Further, when inserting the crimping annular body 5 through the tip of the bolt body 1, the locking projection 52 is formed in a shape that does not interfere with the longitudinal groove portion 16 of the male screw portion 14 and can move along the longitudinal groove portion 16. That is, the locking projection 52 is formed in substantially the same shape as the longitudinal groove portion 16 in a plan view.

[0029] The release restriction projection 53 extends to a position substantially the same as the outer peripheral surface of the disc spring 42 in a plan view. That is, the length from the central portion of the crimping annular body 5 to the tip of the release restriction projection 53 and the length from the central portion to the outer peripheral end of the disc spring 42 (the radius of the disc spring 42 in a plan view) are formed to be substantially the same length.

[0030] The stopper member 6 functions as a wedge for preventing the crimping annular body 5 fitted with the crimping annular body 5 and loosely fitted in the circumferential groove portion 13 from detaching from the circumferential groove portion 13. As shown in FIGS. 5(a) and 5(b), the stopper member 6 includes a stopper member main body 61 formed in a disc shape having a certain thickness, an insertion hole portion 62 provided at the central portion of the stopper member main body 61 and formed to have a diameter slightly larger than the diameter of the male screw portion 14, a guide projection portion 63 protruding from the inner peripheral surface of the stopper member main body 61 toward the central portion, and an engagement projection portion 64 provided at a position shifted in the circumferential direction of the stopper member main body 61 from a straight line drawn radially from the central portion of the stopper member main body 61 through each guide projection portion 63 on the outer peripheral surface of the stopper member main body 61.

[0031] As shown in FIG. 5(b), the guide projection portion 63 is formed in a substantially square shape in a plan view, and its width is formed to be substantially the same as the width of the longitudinal groove portion 16. By forming the guide projection portion 63 to have substantially the same width as the longitudinal groove portion 16 in this way, when the stopper member main body 61 moves along the longitudinal groove portion 16, rotation of the stopper member main body 61 in the circumferential direction can be restricted.

[0032] The engagement projection portion 64 includes a support piece portion 64a vertically provided on the outer peripheral surface of the stopper member main body 61 and an engagement portion 64b bent and extending in the circumferential direction of the stopper member main body 61 from the lower end portion of the support piece portion 64a.

[0033] The support piece portion 64a is a plate-like body having a certain thickness. The support piece portion 64a is formed to have a length such that the release restriction protrusion 53 of the pressure-bonding annular body 5 can be supported by the engaging portion 64b in a state where the lower surface of the stopper member 6 contacts the upper surface of the pressure-bonding annular body 5 from the outer peripheral side surface of the stopper member main body 61.

[0034] The engaging portion 64b has a support piece 64c that supports the release restriction protrusion 53 of the pressure-bonding annular body 5, and a fitting protrusion 64d that protrudes upward at the tip of the support piece 64c. The fitting protrusion 64d is formed to have a thickness approximately half of the vertical thickness of the release restriction protrusion 53. By engaging with the release restriction protrusion 53, the engaging portion 64b can integrally form the stopper member 6 and the pressure-bonding annular body 5.

[0035] Next, a mounting rotator 7 used when fixing the object to be fixed 3 using the loosening prevention structure of the nutless bolt in the present embodiment, and a removal rotator 8 used when releasing the fixed state of the object to be fixed 3 will be described. FIGS. 6(a) and (b) are diagrams showing the configuration of the mounting rotator 7, and FIGS. 7(a) and (b) are diagrams showing the configuration of the removal rotator 8.

[0036] The mounting rotator 7 has an annular rotator main body 71 and a rotation pressing portion 72 protruding from the outer peripheral surface of the rotator main body 71. The rotator main body 71 has a fitting groove portion 73 on its inner peripheral surface. The fitting groove portion 73 is formed in a substantially square shape that is substantially the same shape as the release restriction protrusion 53 in a plan view so as to fit with the release restriction protrusion 53 of the pressure-bonding annular body 5. The fitting groove portion 73 is provided at intervals of approximately 120 degrees in the circumferential direction of the rotator main body 71 in the same manner as the release restriction protrusion 53 provided on the pressure-bonding annular body 5. Also, the length from the central portion of the rotator main body 71 to the inner peripheral wall surface of the fitting groove portion 73 is formed to be slightly longer than the length of the straight line connecting the central portion of the pressure-bonding annular body 5 and the tip of the release restriction protrusion 53. Thereby, the fitting groove portion 73 and the release restriction protrusion 53 can be easily fitted.

[0037] The rotation pressing portion 72 is provided on the outer peripheral surface of the rotary tool body 71 on a straight line extending in the radial direction passing through the fitting groove portion 73 from the central portion of the rotary tool body 71. The rotation pressing portion 72 is a substantially square-shaped portion. In the present embodiment, three rotation pressing portions 72 are provided. In this way, by adopting the configuration of providing the rotation pressing portion 72 on a straight line extending in the radial direction passing through the fitting groove portion 73 from the central portion of the rotary tool body 71, the approximate position of the fitting groove portion 73 can be confirmed without visually recognizing the position of the fitting groove portion 73 provided inside the rotary tool body 71, facilitating the operation of fitting the release regulation protrusion 53 of the pressure-bonding annular body 5 and the fitting groove portion 73. That is, the time for fixing the object to be fixed 3 can be shortened, improving the workability.

[0038] The removal rotary tool 8 includes an annular removal tool body 81 and a removal pressing portion 82 protruding from the outer peripheral surface of the removal tool body 81. The removal tool body 81 has a fitting groove portion 83 and a release protrusion portion 84 on its inner peripheral surface. The fitting groove portion 83 is provided at regular intervals along the circumferential direction on the inner peripheral surface of the removal tool body 81 so as to fit with the release regulation protrusion 53 of the pressure-bonding annular body 5 in the same manner as the fitting groove portion 73 of the mounting rotary tool 7. In the present embodiment, the fitting groove portion 83 is provided at intervals of approximately 120 degrees in the circumferential direction of the removal tool body 81.

[0039] The release protrusion portion 84 is provided on the inner peripheral surface of the removal tool body 81 adjacent to the fitting groove portion 83. The release protrusion portion 84 is formed in substantially the same shape as the longitudinal groove portion 16 of the male screw portion 14 in a plan view. The release protrusion portion 84 is formed from the upper end portion of the removal tool body 81 to a thickness approximately half of the thickness of the removal tool body 81. When the removal rotary tool 8 is used, the lower surface of the release protrusion portion 84 can easily release the fitting state between the pressure-bonding annular body 5 and the stopper member 6 by pressing the upper surface of the fitting protrusion 64d of the stopper member 6 downward.

[0040] The removal pressing portion 82 protrudes radially from the outer peripheral surface of the removal tool main body 81 in a radial direction extending on a straight line passing through each fitting groove portion 83 from the central portion of the removal tool main body 81 and is spaced apart from the central portion of the removal tool main body 81. The removal pressing portion 82 is formed in a substantially square shape. In the present embodiment, three removal pressing portions 82 are provided, which is the same number as the fitting groove portions 83. Note that the removal pressing portions 82 are formed on the outer peripheral surface of the removal tool main body 81 in the same number as the fitting groove portions 83 so that the positions can be recognized without visually recognizing the fitting groove portions 83 formed on the inner peripheral surface of the removal tool main body 81.

[0041] Next, a procedure for fixing the object to be fixed 3 using the mounting rotating tool 7 will be described with reference to FIGS. 1, 8, and 9. FIG. 9 is a diagram showing the procedure of engaging the crimping annular body 5 and the stopper member 6 by the mounting rotating tool 7, where (a) shows the start of engagement, (b) shows the middle of engagement, and (c) shows after engagement.

[0042] First, as shown in FIG. 1, a gripping plate 2, two objects to be fixed 3, 3, a spring member 4, a crimping annular body 5, and a stopper member 6 are loosely fitted or inserted into the bolt body 1 in order from the bottom. At this time, the gripping plate 2, the two objects to be fixed 3, and the spring member 4 are located in the plate holding portion 12 and the circumferential groove portion 13 of the bolt body 1. The crimping annular body 5 and the stopper member 6 are located on the male screw portion 14. The locking protrusion 52 of the crimping annular body 5 and the guide protrusion portion 63 of the stopper member 6 are fitted into the vertical groove portion 16, and rotation of the bolt body 1 in the circumferential direction is restricted.

[0043] Next, the mounting rotating tool 7 is inserted from the tip of the bolt body 1, that is, from the tip of the male screw portion 14, until the rotating tool main body 71 of the mounting rotating tool 7 contacts the upper surface of the disc spring 42 of the spring member 4. At this time, the release restricting protrusion 53 of the crimping annular body 5 is fitted into the fitting groove portion 73 of the mounting rotating tool 7.

[0044] Next, a nut N is screwed onto the threaded portion 15 of the male screw portion 14 of the bolt body 1. When the nut N is tightened on the threaded portion 15, the bottom surface of the nut N contacts the upper surface of the stopper member body 61 of the stopper member 6. From this state, when the nut N is further tightened on the threaded portion 15, the nut N presses the spring member 4 from above via the stopper member 6 and the crimping annular body 5 (see Fig. 9(a)). The nut N is tightened on the threaded portion 15 until the vicinity of the hole portion 42a of the disc spring 42 constituting the spring member 4 contacts the pressing portion 41b of the upper gripping plate 41.

[0045] Next, the rotation pressing portion 72 of the mounting rotator 7 is manually pinched and rotated in either the right direction or the left direction along the circumferential direction of the circumferential groove portion 13. The fitting groove portion 73 of the mounting rotator 7 and the release regulation protrusion 53 are fitted together, and the crimping annular body 5 is rotated in either the left or right direction by the mounting rotator 7.

[0046] As shown in Figs. 9(b) and 9(c), the crimping annular body 5 rotated in either the left or right direction by the mounting rotator 7 has the release regulation protrusion 53 of the crimping annular body 5 overcome the fitting protrusion 64d of the stopper member 6 and is supported by the support piece 64c. The release regulation protrusion 53 supported by the support piece 64c of the stopper member 6 continues to maintain the engagement state with the engaging portion 64b by the fitting protrusion 64d. Thereby, the crimping annular body 5 and the stopper member 6 are engaged and integrated, and the crimping annular body 5 and the stopper member 6 do not come off from the tip of the bolt body 1 via the longitudinal groove portion 16 of the male screw portion 14, and the fixed state of the object to be fixed 3 is not released. As described above, since the guide protrusion portion 63 of the stopper member 6 is fitted into the longitudinal groove portion 16, the rotation of the bolt body 1 in the circumferential direction is restricted. That is, the rotation of the crimping annular body 5 integrated with the stopper member 6 in the circumferential direction of the bolt body 1 is also restricted.

[0047] In addition, the elastic force acting on the tip end side of the bolt body 1 caused by the deformation of the disc spring 42 of the spring member 4 is restricted by the engagement of the locking projection 52 of the crimping annular body 5 with the lower end portion of the male screw portion 14. That is, even if the crimping annular body 5 is urged toward the tip end side of the bolt body 1 by the elastic force of the disc spring 42, the engagement of the locking projection 52 with the lower end portion of the male screw portion 14 restricts the movement of the crimping annular body 5 toward the tip end side of the bolt body 1, and the fixed state of the object 3 to be fixed does not become loose. In the present embodiment, in a plan view, the direction in which the crimping annular body 5 is rotated clockwise is defined as the direction in which the object 3 to be fixed is fixed, and the direction in which the crimping annular body 5 is rotated counterclockwise is defined as the direction for releasing the fixation of the object 3 to be fixed.

[0048] In this way, after the crimping annular body 5 and the stopper member 6 are engaged so as to be integrated and the object 3 to be fixed is fixed, the fitting state between the fitting groove portion 73 of the mounting rotary tool 7 and the release regulation projection 53 of the crimping annular body 5 is released, and the mounting rotary tool 7 is removed from the tip end side of the bolt body 1.

[0049] Then, the nut N screwed onto the screw portion 15 of the male screw portion 14 is loosened, and the nut N is removed from the male screw portion 14. Thereby, the fixing operation of the object 3 to be fixed by the anti-loosening structure of the nutless bolt is completed.

[0050] As described above, in the anti-loosening structure of the nutless bolt according to the present embodiment, by engaging the locking projection 52 of the crimping annular body 5 with the lower end portion of the male screw portion 14 to restrict the upward movement of the crimping annular body 5, the elastic force of the disc spring 42 of the spring member 4 is generated in the direction toward the plate receiving portion 11 of the bolt body 1, and the object 3 to be fixed can be fixed between the upper gripping plate 41 and the gripping plate 2 by the elastic force of this spring member 4.

[0051] Next, a procedure for removing the object 3 to be fixed from the state fixed by the anti-loosening structure of the nutless bolt will be described with reference to FIGS. 10(a), (b), and (c).

[0052] First, the fitting groove portion 83 of the removal rotating tool 8 is fitted to the release restricting projection 53 of the crimping annular body 5 that fixes the object to be fixed 3. At this time, the removal rotating tool 8 has descended until the removal tool main body 81 is placed on the disc spring 42. The lower surface of the release projection portion 84 of the removal rotating tool 8 is in contact with the upper surface of the fitting projection 64d, and the fitting groove portion 83 is fitted to the release restricting projection 53.

[0053] Next, a nut N is screwed onto the screw portion 15 of the male screw portion 14. At this time, the nut N is tightened on the screw portion 15 until it contacts the stopper member main body 61 of the stopper member 6. The nut N further presses the release projection portion 84 of the removal rotating tool 8 from above to below by tightening it on the screw portion 15 in a state of contacting the stopper member main body 61. Then, the release projection portion 84 presses the fitting projection 64d of the stopper member 6 to release the restriction of the release restricting projection 53. That is, the release projection portion 84 presses the fitting projection 64d so that the upper end portion of the fitting projection 64d is positioned below the lower surface of the release restricting projection 53.

[0054] Next, while keeping the lower surface of the release projection portion 84 in contact with the fitting projection 64d, the removal rotating tool 8 is rotated in a direction to release the engagement state between the crimping annular body 5 and the stopper member 6. In the present embodiment, in a plan view, by rotating the removal rotating tool 8 counterclockwise, the engagement state between the release restricting projection 53 and the fitting projection 64d is released. At this time, the crimping annular body 5 rotated by the removal rotating tool 8 is rotated in a plan view until the locking projection 52 overlaps with the guide projection portion 63 of the stopper member 6.

[0055] Thereafter, the fitting state between the fitting groove portion 83 of the removal rotating tool 8 and the release restricting projection 53 of the crimping annular body 5 is released, and the removal rotating tool 8 is removed from the tip side of the bolt body 1.

[0056] Then, by loosening the nut N screwed onto the threaded portion 15 of the male screw portion 14 of the bolt body 1 and removing it from the threaded portion 15, the fixed state of the object 3 to be fixed is released. That is, by loosening the tightening of the nut N, the disc spring 42 of the spring member 4 returns to its original frustoconical shape due to its elastic action, and in the process, the crimping annular body 5 and the stopper member 6 are moved along the longitudinal groove portion 16 to the tip side of the bolt body 1. As a result, the object 3 to be fixed is released from the fixed state, and the object 3 to be fixed by the anti-loosening structure of the nutless bolt is released from the fixed state.

[0057] Since the anti-loosening structure of the nutless bolt according to the present embodiment is configured as described above, by using the anti-loosening structure with the crimping annular body 5 and the stopper member 6 having unique shapes, nutless is realized when fixing the object 3 to be fixed, and the problem that the male screw of the bolt is crushed is completely solved. At the same time, the fixing operation of the object 3 to be fixed can be carried out with substantially the same work content as the fastening operation with the conventional bolt and nut. Further, the anti-loosening structure of the nutless bolt according to the present embodiment can realize the anti-loosening structure regardless of the materials of the crimping annular body 5 and the stopper member 6 that realize the anti-loosening structure.

[0058] Also, when the object 3 to be fixed is fixed, by engaging the crimping annular body 5 and the stopper member 6 to be integrated, even if vibration or impact is applied to the bolt body 1 or the object 3 to be fixed, the movement of the crimping annular body 5 in the circumferential direction is restricted by the stopper member 6, and the movement of the bolt to the tip side is restricted by the lower end portion of the male screw portion 14 and the locking projection 52, so that an anti-loosening structure of a nutless bolt can be realized in which the force for fixing the object 3 to be fixed does not decrease.

[0059] Further, since the rotation operation of the crimping annular body 5 loosely fitted in the circumferential surface groove portion 13 is performed by the mounting rotating tool 7 and the removing rotating tool 8 having a larger rotation radius than the crimping annular body 5, the engagement of the crimping annular body 5 with the stopper member 6 can be easily realized.

[0060] Also, in the anti-loosening structure of the nutless bolt in this embodiment, although the method of pressing the spring member 4 from above using the nut N to fix or remove the objects to be fixed 3, 3 has been described, the present invention is not limited to this. It may be configured such that a press device can be used as means for pressing the spring member 4 from above downward to fix or remove the objects to be fixed 3, 3. In this way, with a configuration in which the spring member 4 is pressed from above downward using a press device to fix or remove the objects to be fixed 3, 3, the operation of screwing the nut N onto the male screw portion 14 can be omitted, and the time for the operation of fixing or removing the objects to be fixed 3, 3 can be further shortened.

[0061] Note that the present invention is not limited to the above-described embodiments, and also includes configurations in which the respective configurations disclosed in the above-described embodiments are mutually replaced or changed, known inventions, and configurations in which the respective configurations disclosed in the above-described embodiments are mutually replaced, etc. Further, the technical scope of the present invention is not limited to the above-described embodiments, and extends to the matters described in the claims and their equivalents.

Explanation of Reference Numerals

[0062] 1 Bolt body 2 Gripping plate 2a Insertion hole portion 3 Object to be fixed 4 Spring member 5 Crimping annular body 6 Stopper member 7 Mounting rotator 8 Removing rotator 11 Plate receiving portion 12 Plate holding portion 13 Peripheral surface groove portion 14 Male screw portion 15 Threaded portion 16 Longitudinal groove portion 41 Upper gripping plate 41a Insertion hole portion 42 Disc spring 42a Hole portion 51 Insertion hole portion 52 Locking projection 53 Release regulation protrusion 54 Annular body 61 Stopper member body 62 Insertion hole part 63 Guide protrusion part 64 Engagement protrusion part 64a Support piece part 64b Engagement part 64c Support piece 64d Fitting protrusion 71 Rotating tool body 72 Pressing part for rotation 73 Fitting groove part 81 Removing tool body 82 Pressing part for removal 83 Fitting groove part 84 Release protrusion part N Nut

Claims

1. a plate receiving portion, a plate holding portion connected to the plate receiving portion, a circumferential groove portion connected to the tip of the plate holding portion, a male screw portion having a longitudinal groove portion connected to the tip of the circumferential groove portion, a bolt body provided with the above, a gripping plate loosely fitted in the plate holding portion, a spring member loosely fitted in the plate holding portion and disposed opposite to the gripping plate, a crimping annular body loosely fitted in the circumferential groove portion and connected to the spring member, a stopper member for restricting the crimping annular body from detaching from the circumferential groove portion, A loosening prevention structure for a nutless bolt including the above.

2. The crimping annular body is provided with a release restriction projection on its outer peripheral surface, and the stopper member is provided with an engaging projection. The loosening prevention structure of the nutless bolt according to claim 1, wherein the release of the crimping annular body from the circumferential groove portion is restricted by engaging the release restriction projection and the engaging projection. ​

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