Unidirectional fastener

Abstract

To provide a unidirectional fastener with a small number of components.SOLUTION: A unidirectional fastener comprises a bolt 1, a nut 2 to be screwed onto the bolt 1, and a sleeve 4 which can pass through penetration holes 5K, 6K in fastened plate materials 5, 6 when it is disposed on a shaft part 1B of the bolt 1. The sleeve 4 deforms under an axial compression force along with fastening of the bolt 1 and the nut 2, the deformation being such that a partial region of the sleeve 4 in the axial direction is bent and deformed into a substantially V-shape while separating from the bolt 1 to the radially outer side. Of the two sides constituting the substantially V-shape as bent and deformed, a first side 4C on a side closer to the fastened plate materials 5, 6 is shorter than a second side 4D on a side farther from the fastened plate materials 5, 6. An end face 4A on the near side, which is the side of fastening of the sleeve 4, coincides with an end edge 5A on the near side of the fastened plate materials 5, 6 in the axial direction before fastening, and moves away from the near-side end edge 5A toward the far side as bending and deformation proceeds.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a one-way fastener. [Background technology]

[0002] A one-way fastener is a fastener that can penetrate and tighten a fastened plate material having a through hole from one direction, the front side as seen by the worker.

[0003] As the one-way fastener, a blind bolt is proposed in Patent Document 1. This blind bolt includes a core bolt that can pass through a through hole formed in a workpiece as a plate material to be fastened, a nut screwed into the shank of the core bolt, a bearing washer located between the nut and the workpiece and fitted on the outside of the shank of the core bolt, a shear washer fitted inside the bearing washer, an expandable sleeve fitted on the shank of the core bolt so as to cover the outer periphery of the side of the shank of the core bolt that is closer to the head, and a main sleeve fitted on the shank of the core bolt so as to cover the outer periphery of the side of the shank of the core bolt that is farther from the head. When the bolt and the nut are fastened from the front side of the workpiece, the sleeve receives a compressive force in the axial direction, and a part of the axial region of the sleeve is deformed so as to bulge radially outward, and when the compressive force reaches a predetermined compressive force, the main sleeve moves to the front side and breaks the shear washer, completing the fastening of the workpiece. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3816130 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above Patent Document 1, not only is a shear washer required to be installed inside the bearing washer, but a main sleeve is also required to break the shear washer, which not only increases the number of parts that make up the blind bolt but also increases the assembly labor, leaving room for improvement.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a one-way fastener that has a reduced part count. [Means for solving the problem]

[0007] The one-way fastener of the present invention comprises a bolt capable of passing through a through hole formed in a plate material to be fastened, a nut screwed onto the shank of the bolt, and a sleeve attached to the shank so as to cover the outer circumference of the shank of the bolt and capable of passing through a through hole in the plate material to be fastened while attached to the shank. The sleeve is configured to deform under an axial compressive force as the bolt and the nut are tightened. The deformation is a cross-sectional shape along the axial direction in which a portion of the axial region of the sleeve is bent and deformed radially outward from the bolt into an approximately V-shape. Of the two sides that constitute the bent and deformed approximately V-shape, the first side that is closer to the plate material to be fastened is shorter than the second side that is farther from the plate material to be fastened. The end face of the sleeve on the front side, which is the side to be tightened, is axially aligned with the front edge of the plate material to be fastened before tightening, and moves away from the front edge to the rear side as the bending deformation progresses.

[0008] According to this configuration, the one-way fastener is composed of a bolt, a nut screwed onto the shank of the bolt, and a sleeve that is deformed by receiving a compressive force in the axial direction as the bolt and the nut are fastened, thereby reducing the number of parts. In addition, the end face on the front side of the sleeve that is the fastening side moves away from the front end edge to the rear side as the bending deformation progresses, so that the compressive force in the axial direction generated by the fastening of the bolt and the nut can be reliably applied between the nut and the part that is bent and deformed into an approximately V-shape (a part that bulges outward in the radial direction, also called a bulge). This allows the fastened plate material to be reliably fastened by the one-way fastener. In addition, of the two sides that form the approximately V-shape that is bent and deformed, the first side that is closer to the fastened plate material is shorter than the second side that is farther from the fastened plate material. Therefore, when the two sides are deformed to approach each other as the bending deformation progresses, the shorter first side is pulled outward in the radial direction by the longer second side. This allows the diameter of the bulge to be increased, thereby improving the effect of preventing the one-way fastener from coming off the fastened plate material.

[0009] In addition, in the one-way fastener of the present invention, the sleeve has a weak portion whose strength with respect to the compressive deformation is weaker than other portions in the axial direction, and the bending deformation is caused by plastic deformation of the weak portion, and after the bending deformation begins, the position of the end of the first side that is closer to the fastened plate material may be coincident in the axial direction with the rear edge of the through hole.

[0010] As described above, the plastic deformation of the weak portion causes bending deformation of the sleeve, and after the bending deformation starts, if the position of the end of the first side closest to the fastened plate material is in the same axial position as the rear edge of the through hole, the first side can be brought into contact with the fastened plate material, and the bending deformation can proceed. As the bending deformation progresses, the front part of the sleeve on the front side of the first side can be pulled toward the rear side, and the front end face on the fastening side of the sleeve can be reliably moved away from the front edge toward the rear side.

[0011] In addition, in the one-way fastener of the present invention, the sleeve has a weak portion whose strength with respect to the compressive deformation is weaker than other portions in the axial direction, and the bending deformation is caused by plastic deformation of the weak portion, and after the bending deformation begins, the position of the end of the first side closer to the fastened plate material may be located near the rear edge of the through hole and further inside the through hole than the rear edge.

[0012] As described above, the weak portion undergoes plastic deformation, causing bending deformation of the sleeve, and after the bending deformation begins, if the end of the first side closest to the fastened plate material is located near the rear edge of the through hole and further inside the through hole than the rear edge, the first side can be brought into contact with the fastened plate material, and the bending deformation can proceed. As the bending deformation progresses, the sleeve can be pulled toward the rear side, and the end face on the front side, which is the side that is fastened, can be reliably moved away from the front edge to the rear side.

[0013] Furthermore, in the one-way fastener of the present invention, the position where the outer peripheral surface of the sleeve abuts against the rear end edge of the through hole after the bending deformation begins may be the starting point of the bending deformation.

[0014] As described above, if the position where the outer circumferential surface of the sleeve abuts against the rear edge of the through hole after the start of bending deformation is the starting point of bending deformation, the outer circumferential surface of the sleeve can be kept in a state of abutment against the rear edge of the through hole, and bending deformation can proceed. As the bending deformation proceeds, the sleeve can be pulled toward the rear side, so that the front end surface of the sleeve, which is the tightening side, can be reliably moved away from the front edge toward the rear side.

[0015] In addition, the one-way fastening device of the present invention may be arranged so that the bolt has its head positioned at the rear side of the fastened plate material, and the radial dimension of the head may be smaller than the diameter of the through hole.

[0016] According to the above configuration, the head side of the bolt can be passed through the through hole of the fastened plate material from the front side of the fastened plate material to fasten the plate material, so there is no need to reach to the back side or place a tool.

[0017] In addition, in the one-way fastener of the present invention, the bolt may further include a breaking portion at a front end portion of the fastened plate material, the breaking portion being supported so as to immobilize the bolt in the circumferential direction during the tightening, and being broken off from the shank of the bolt and removed after tightening of the nut is completed.

[0018] According to the above configuration, after the nut has been completely tightened, the broken portion is broken off from the shank of the bolt and removed, allowing the worker to visually confirm that fastening has been completed. Effect of the Invention

[0019] As described above, by configuring a one-way fastener with a bolt, a nut, and a sleeve having a deformation portion that deforms when compressed by tightening the bolt and the nut, it is possible to provide a one-way fastener with a small number of parts, and therefore the number of assembly steps for assembling the one-way fastener is also reduced. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is an oblique view of the one-way fastener of the first embodiment, viewed from the rear side of the plate materials to be fastened. [Diagram 2] FIG. 2 is a perspective view of the one-way fastener of the first embodiment, viewed from the front side of the fastened plate materials. [Diagram 3] 3(a) is a vertical cross-sectional view showing the one-way fastener of FIG. 1 inserted into a through hole in a plate material to be fastened, and FIG. 3(b) is a vertical cross-sectional view showing the one-way fastener of FIG. 3(a) tightened. [Figure 4] FIG. 4(a) is a vertical cross-sectional view showing a state in which the one-way fastener is further tightened from the state shown in FIG. 3(b), and FIG. 4(b) is a vertical cross-sectional view showing the state in which the one-way fastener is tightened from the state shown in FIG. 4(a) and tightening is completed. [Diagram 5]1A and 1B show a one-way fastener according to a second embodiment, in which (a) is a vertical cross-sectional view of the one-way fastener just before tightening, and (b) is a vertical cross-sectional side view of the one-way fastener after tightening has been completed. [Figure 6] 10A and 10B show a one-way fastener according to a third embodiment, in which FIG. 10A is a vertical cross-sectional view of the one-way fastener immediately before tightening, and FIG. 10B is a vertical cross-sectional view of the one-way fastener when tightening has begun. [Figure 7] FIG. 7 is a vertical sectional side view of the one-way fastener showing a state where the one-way fastener has been further tightened from the state shown in FIG. 6(b) and has been completely tightened. [Figure 8] 10A and 10B show a one-way fastener according to a fourth embodiment, in which FIG. 10A is a vertical cross-sectional view of the one-way fastener immediately before tightening, and FIG. 10B is a vertical cross-sectional view of the one-way fastener when tightening has begun. [Figure 9] 8(a) is a vertical cross-sectional view of the one-way fastener showing a state where it has been further tightened from the state shown in FIG. 8(b), and FIG. 8(b) is a vertical cross-sectional view of the one-way fastener after tightening has been completed. [Figure 10] 1A and 1B show a one-way fastener of a different form from the first embodiment, where (a) is a vertical cross-sectional view of the one-way fastener just before tightening, and (b) is a vertical cross-sectional view of the one-way fastener after tightening has been completed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] First Embodiment The one-way fastener (also called one-sided bolt) T of the first embodiment is shown in Figures 1 and 2, 3(a), (b), and 4(a), (b), and is equipped with a bolt 1, a nut 2, a washer 3, and a sleeve 4, and is for fastening plate materials 5, 6 made of multiple overlapping steel plates (two in the figures). In Figures 3(a), (b) to 9(a), (b), the lower side of the plate materials 5, 6 to be fastened is the near side, and the upper side of the plate materials 5, 6 to be fastened is the far side.

[0023] 1 and 3(a), the bolt 1 has a head 1A with a circular cross section and a shank 1B with an outer diameter smaller than that of the head 1A. The bolt 1 is arranged so that the head 1A is located at the rear side of the fastened plate materials 5, 6, and the outer diameter of the head 1A is smaller than the hole diameter of the circular through holes 5K, 6K formed in the fastened plate materials 5, 6. A male thread 1N is formed on the outer surface of the shank 1B, and a female thread 2N of a nut 2 is screwed into the male thread 1N.

[0024] 2, the cross-sectional shape of the outer surface of the nut 2 is a regular hexagon. At the center of the nut 2, a female threaded portion 2N is formed into which the male threaded portion 1N of the shaft portion 1B of the bolt 1 is screwed.

[0025] The washer 3 is configured in a circular plate shape with a through hole 3K formed in the center through which the shank 1B of the bolt 1 can pass. As shown in Fig. 3(a), when the one-way fastener T is inserted into the through holes 5K, 6K formed in the fastened plate materials 5, 6, a first surface 3B on one side in the plate thickness direction of the washer 3 (the upper side in Fig. 3(a)) abuts against a front end surface 5T of the fastened plate material 5 located on the front side, and a second surface 3A on the other side in the plate thickness direction of the washer 3 (the lower side in Fig. 3(a)) abuts against an upper end surface 2B of the nut 2.

[0026] The sleeve 4 is formed in a substantially cylindrical shape having an inner diameter that allows it to be fitted onto the shank 1B of the bolt 1, and both the outer and inner cross-sectional shapes are circular. As shown in FIG. 3(a), the sleeve 4 is in a state in which the rear end face 4B abuts against the end face 1a on the shank 1B side (near side) of the head 1A of the bolt 1, and the near side end face 4A abuts against the first surface 3B of the washer 3. When the bolt 1 and the nut 2 are tightened in this state, the sleeve 4 is deformed by the axial compressive force caused by the head 1A and the nut 2 approaching each other. The deformation is such that a part of the axial region of the sleeve 4 in the cross-sectional shape along the axial direction is bent and deformed in a substantially V-shape away from the shank 1B of the bolt 1 radially outward (see FIG. 3(b)).

[0027] As shown in Figure 3(b), of the two sides that constitute the approximately V-shape after bending, the first side (approximately horizontal side) 4C closer to the fastened plate material 6 located at the rear is shorter than the second side (hypothetical side) 4D farther from the fastened plate material 6 at the rear, and the front end face 4A of the sleeve 4, which is the tightening side, axially coincides with the front edge 5A of the through hole 5K of the fastened plate material 5 located at the front before tightening, and moves away from the front edge 5A to the rear as the bending deformation progresses (see Figures 4(a) and (b)).

[0028] The sleeve 4 has a weak portion 7 whose strength against the compressive deformation is weaker than other portions in the axial direction, and the bending deformation occurs due to the plastic deformation of the weak portion 7. After the bending deformation starts, the position of the end portion of the first side 4C close to the back fastened plate material 6 is in the same position in the axial direction as the back edge 6A of the through hole 6K of the fastened plate material 6, so that the end portion 4c close to the back fastened plate material 6 of the first side 4C can be abutted against the back end surface 6T of the fastened plate material 6, and the bending deformation can proceed (see Figs. 4(a) and (b)). As the bending deformation proceeds, the sleeve 4 can be pulled toward the back side. This ensures that the front end surface 4A of the sleeve 4, which is the tightening side, can be moved away from the front edge 5A of the fastened plate material 5 to the back side (upper side in Figs. 4(a) and (b)).

[0029] As shown in FIG. 1 and FIG. 3(a), the fragile portion 7 is composed of a plurality of substantially V-shaped grooves 7A, 7B, 7C, and 7D formed in the sleeve 4 to make the thickness of the sleeve 4 thinner than other portions in the axial direction. The grooves 7A, 7B, 7C, and 7D are all formed over the entire circumferential area, but they can also be composed of a plurality of grooves that are discontinuous in the circumferential direction by changing the depth of the grooves and the size of the axial width of the grooves. The grooves 7A, 7B, and 7D are bending points when the sleeve 4 is bent and deformed. The groove 7C is a groove for partially reducing the outer diameter of the sleeve 4 to make it easier to bend and deform. Also, as shown in FIG. 3(b), it is a groove for floating the portion of the first side 4C on the outer diameter side from the end 4c of the end 4c of the first side 4C from the rear end surface 6T of the rear fastened plate material 6 when the sleeve 4 is bent and deformed into a substantially V-shape. As the bending deformation progresses further, the second side 4D extends toward the outer diameter side, pushing down the tops of the first side 4C and the second side 4D, and a seesaw effect occurs, with the end 4c of the first side 4C acting as a fulcrum to slightly lift the lower part 4E opposite the tops (see Figure 4(a)).

[0030] The first groove 7A, which is closest to the back fastened plate material 6 among the grooves 7A, 7B, 7C, and 7D, is formed on the outer surface of the sleeve 4 at the same axial position as the back edge 6A of the through hole 6K of the back fastened plate material 6. The second groove 7B, which is farthest from the back fastened plate material 6 among the grooves 7A, 7B, 7C, and 7D, is formed on the outer surface of the sleeve 4 at a position close to the head 1A of the bolt 1. The third groove located between the first groove 7A and the second groove 7B includes an outer surface side third groove 7C formed on the outer surface of the sleeve 4 and an inner surface side third groove 7D formed on the inner surface of the sleeve 4 at the same axial position as the outer surface side third groove 7C. The first groove 7A, the second groove 7B, and the inner surface side third groove 7D are configured as grooves of approximately the same shape and approximately the same size. The outer surface side third groove 7C is formed to be deeper radially inward than the first groove 7A, the second groove 7B, and the inner surface side third groove 7D, and has a larger axial width. The axial positions of the two third grooves 7C and 7D are set closer to the first groove 7A than the axial center position between the first groove 7A and the second groove 7B.

[0031] The procedure for fastening the plate members 5, 6 using the one-way fastener T configured as above will now be described.

[0032] 3(a) shows a state in which the one-way fastener T is inserted from the front side (the lower side in the figure) into the through holes 5K, 6K of the fastened plate materials 5, 6 with the head 1A of the bolt 1 at the front end. At this time, the one-way fastener T is inserted into the through holes 5K, 6K of the fastened plate materials 5, 6 until the first surface (rear end surface) 3B of the washer 3 abuts against the front end surface 5T of the fastened plate material 5 on the front side.

[0033] Next, the nut 2 is rotated while the shaft portion of the bolt 1 is supported so as not to rotate using a general-purpose tightening tool (not shown). Then, as shown in FIG. 3(b), the bolt 1 screwed into the female thread portion 2N of the nut 2 moves forward. At this time, the sleeve 4 receives a compressive force in the axial direction, and the sleeve 4 is plastically deformed at the first groove 7A, the second groove 7B, the outer surface side third groove 7C, and the inner surface side third groove 7D, and the region from the first groove 7A to the second groove 7B of the sleeve 4 is bent and deformed in a substantially V-shape, moving away from the shaft portion 1B of the bolt 1 radially outward (see FIG. 3(b)). Of the two sides 4C, 4D constituting this approximate V-shape, the first side 4C closer to the back fastened plate material 6 is shorter than the second side 4D farther from the back fastened plate material 6, so that the axial positions of the outer surface side third groove 7C and the inner surface side third groove 7D located between the first groove 7A and the second groove 7B are set closer to the first groove 7A (see FIG. 3(a)). In other words, the approximate V-shape is asymmetric between the front side and the back side.

[0034] 3(b), the position of the end 4c on the first side 4C closest to the back of the fastened plate material 6 is in the same axial position as the back edge 6A of the through hole 6K of the fastened plate material 6. In other words, the end 4c on the back side of the first side 4C closest to the fastened plate material 6 can be abutted against the back end face 6T of the fastened plate material 6. When the nut 2 is further rotated from this state, the part 4E of the sleeve 4 below the first side 4C is pulled toward the back of the through holes 5K, 6K (upward in the figure) with the abutting end 4c as a fulcrum (see FIG. 4(a)).

[0035] When the nut 2 is further rotated, the lower part 4E of the sleeve 4 is further pulled toward the inner side (upper side in the figure) of the through holes 5K, 6K (see FIG. 4(b)). In this way, the front end face 4A of the sleeve 4, which is the tightening side, moves away from the front end edge 5A of the through hole 5K of the fastened plate material 5 on the front side toward the inner side as the bending deformation progresses. As a result, after the bending deformation of the sleeve 4, no force is directly transmitted between the washer 3 and the sleeve 4. Therefore, all of the axial compressive force (axial force) generated by the fastening of the bolt 1 and the nut 2 can be surely applied between the nut 2, the washer 3, and the part 8 that is bent and deformed into a substantially V-shape and bulges outward in the radial direction (the part that bulges outward in the radial direction, also called a bulge). As a result, the fastened plate materials 5, 6 can be surely fastened by the one-way fastener T. In addition, the longer second side 4D pulls the shorter first side 4C outward in the radial direction, thereby enhancing the effect of preventing the one-way fastener T from slipping out of the fastened plate materials 5, 6.

[0036] Moreover, the bolt 1 of the one-way fastener T may be configured as shown in FIG. 10(a). That is, the bolt 1 may further include a breaking portion 9 at the front end of the shank 1B of the bolt 1. The breaking portion 9 is supported so as to immobilize the bolt 1 in the circumferential direction when the bolt 1 and the nut 2 are tightened, and is broken and removed from the shank 1B of the bolt 1 after the tightening of the nut 2 is completed. Specifically, the breaking portion 9 is configured to include a grip portion 9A having an outer diameter smaller than that of the shank 1B at the end (free end) of the shank 1B of the bolt 1 that is away from the head 1A, and a breaking groove 9B formed around the entire periphery at the boundary between the shank 1B and the grip portion 9A. Then, the operator can support the bolt 1 so as to immobilize (non-rotate) in the circumferential direction by gripping the grip portion 9A using a tightening tool. In this state, when the nut 2 is rotated and a tightening torque equal to or greater than a predetermined value is reached, the grip portion 9A is broken at the breaking groove 9B and removed. In this way, after the nut 2 has been completely tightened, the breaking portion 9 is broken off from the shaft portion 1B of the bolt 1 and removed, allowing an operator to visually confirm that the fastening has been completed. Note that the bolts 1 of the second to fourth embodiments described below may also be configured in the same manner as in Fig. 10(a).

[0037] <Second embodiment> A second embodiment of the one-way fastener T is shown in Figures 5(a) and (b), and differs from the one-way fastener T of the first embodiment in that some of the four grooves that form the fragile portion 7 provided in the sleeve 4 are different, and other parts other than the grooves are the same, and therefore a description of the other parts will be omitted.

[0038] Regarding the four grooves 10A, 10B, 10C, and 10D constituting the weak portion 10 provided in the sleeve 4, the first grooves closest to the backside fastened plate material 6 among the four grooves 10A, 10B, 10C, and 10D are the outer surface side first groove 10A and the inner surface side first groove 10B formed on the outer surface and the inner surface of the sleeve 4 at the same axial position as the inner edge 6A of the through hole 6K of the fastened plate material 6. In addition, the second groove 10C, which is the furthest from the backside fastened plate material 6 among the grooves 10A, 10B, 10C, and 10D, is formed on the outer surface of the sleeve 4 at a position close to the head 1A of the bolt 1. The third groove 10D located between the two first grooves 10A, 10B and the second groove 10C is formed on the inner surface of the sleeve 4. The inner surface side first groove 10B and the second groove 10C are configured to have approximately the same shape and approximately the same size. The outer first groove 10A is formed to be deeper radially inward than the inner first groove 10B, the second groove 10C, and the third groove 10D, and to be wider in the axial direction. The third groove 10D is larger than the inner first groove 10B and the second groove 10C, and the axial position of the third groove 10D is set to be closer to the first grooves 10A and 10B than the axial center position between the first grooves 10A and 10B and the second groove 10C. The outer first groove 10A constitutes a bending point, but is a groove for partially reducing the outer diameter of the sleeve 4 and moving the bending point closer to the inner diameter side of the sleeve 4. Therefore, the outer first groove 10A is made larger than the inner first groove 10B.

[0039] When the one-way fastener T of the second embodiment is inserted through the through holes 5K, 6K of the plate materials 5, 6 as in FIG. 3(a) (see FIG. 5(a)), and the nut 2 is rotated while the shaft portion 1B of the bolt 1 is supported so as not to rotate using a tightening tool (not shown), the bolt 1 screwed into the female thread portion 2N of the nut 2 moves to the front side as shown in FIG. 5(b). At this time, the sleeve 4 is subjected to a compressive force in the axial direction, and the sleeve 4 is plastically deformed at the outer surface first groove 10A, the inner surface first groove 10B, the second groove 10C, and the third groove 10D, and the region of the sleeve 4 from the first grooves 10A, 10B to the second groove 10C is bent and deformed in a substantially V-shape away from the shaft portion 1B of the bolt 1 radially outward, and the front end portion 4c abuts against the rear end surface 6T of the plate material 6 to be fastened at the rear side of the first side 4C. When the nut 2 is further rotated, the first side 4C is pulled outward in the radial direction by the longer second side 4D, and the effect of preventing the one-way fastener T from coming off the fastened plate materials 5, 6 can be enhanced. Also, the portion 4E below the first side 4C of the sleeve 4 is pulled toward the inner side of the through holes 5K, 6K, and the front end surface 4A of the sleeve 4, which is the fastening side, moves away from the front end edge 5A of the fastened plate material 5 on the front side toward the inner side as the bending deformation progresses. This ensures that the axial compressive force generated by the fastening of the bolt 1 and the nut 2 is applied between the nut 2 and the washer 3 and the portion 8 bent and deformed into a substantially V-shape (a portion bulging outward in the radial direction, also called a bulge). This ensures that the one-way fastener T can fasten the fastened plate materials 5, 6.

[0040] <Third embodiment> The third embodiment of the one-way fastener T is shown in Figures 6(a), (b) and 7. The one-way fastener T differs from the first embodiment in that some (the number) of the four grooves forming the weakened portion 7 provided in the sleeve 4 are different, and other parts other than the grooves are the same, so a description of the other parts will be omitted.

[0041] Regarding the three grooves constituting the fragile portion 11 provided in the sleeve 4, the V-shaped first groove 11A, which is the closest to the backside fastened plate material 6 among the three grooves 11A, 11B, and 11C, is formed near the back side edge 6A of the through hole 6K of the fastened plate material 6 and on the outer surface inside the through hole 6K from the back side edge 6A. The V-shaped second groove 11B, which is the furthest from the backside fastened plate material 6 among the grooves 11A, 11B, and 11C, is formed on the outer surface of the sleeve 4 at a position close to the head 1A of the bolt 1. The V-shaped third groove 11C located between the first groove 11A and the second groove 11B is formed on the inner surface of the sleeve 4. The first groove 11A and the second groove 11B are configured to have approximately the same shape and the same size. The third groove 11C is formed to be deeper radially inward than the first groove 11A and the second groove 11B and to be wider in the axial direction. Further, the axial position of the third groove 11C is set to a position closer to the first groove 11A than the axial center position between the first groove 11A and the second groove 11B.

[0042] When the one-way fastener T of the third embodiment is inserted into the through holes 5K, 6K of the plate materials 5, 6 to be fastened (see FIG. 6(a)) as in FIG. 3(a), and the nut 2 is rotated while the shank 1B of the bolt 1 is supported so as not to rotate using a tightening tool (not shown), the bolt 1 screwed into the female threaded portion 2N of the nut 2 moves forward as shown in FIG. 6(b). At this time, the sleeve 4 is subjected to a compressive force in the axial direction, so that the first groove 11A, the second groove 11B, and the third groove 11C of the sleeve 4 are plastically deformed, and the region from the first groove 11A to the second groove 11B of the sleeve 4 is bent and deformed in a substantially V-shape, away from the shank 1B of the bolt 1 radially outward. At this time, the first side 4C, which is an inclined side forming a substantially V-shape, protrudes from the through hole 6K so as to extend obliquely upward, and the lower part 4e of the outer surface of the protruding first side 4C abuts against the rear end edge 6A of the through hole 6K (see FIG. 6(b)). By further rotating the nut 2, the lower part 4e of the first side 4C abutting against the rear end edge 6A of the through hole 6K becomes a fulcrum, and the part 4E below the first side 4C of the sleeve 4 is pulled out toward the rear side (upward in FIG. 6(b)). As a result, the front end face 4A of the sleeve 4, which is the tightening side, moves away from the front end edge 5A of the fastened plate material 5 on the front side as the bending deformation progresses (see FIG. 7), so that the axial compressive force generated by tightening the bolt 1 and the nut 2 can be surely applied between the nut 2 and the part 8 bent and deformed into a substantially V-shape (the part bulging outward in the radial direction, also called a bulge). This allows the fastened plate materials 5, 6 to be securely fastened by the one-way fastener T.

[0043] <Fourth embodiment> A fourth embodiment of the one-way fastener T is shown in Figures 8(a), (b) and 9(a), (b). The difference from the one-way fastener T of the first embodiment is that the number of grooves formed in the sleeve 4 is reduced by two, and the one-way fastener T is composed of two grooves. The other parts are the same except for the grooves, and a description of the other parts will be omitted. The planned formation position of the first side 4C is determined by grooves 12A and 12B. On the other hand, there is no groove that determines the planned formation position of the second side 4D.

[0044] The two grooves constituting the fragile portion 12 of the sleeve 4 will be described. The first groove 12A, which is closer to the back of the fastened plate material 6 of the two grooves 12A and 12B, is formed on the inner surface of the sleeve 4 at a position away from the through hole 6K of the fastened plate material 6. The second groove 12B, which is farther from the back of the fastened plate material 6 of the two grooves 12A and 12B, is formed on the outer surface of the sleeve 4 at a position closer to the head 1A of the bolt 1. The first groove 12A is formed to be deeper radially inward than the second groove 12B and has a larger axial width. The axial position of the first groove 12A is set at a position where a portion 4G (see FIG. 8(b)) of the outer peripheral surface of the sleeve 4 abuts against the back end edge 6A of the through hole 6K after the sleeve 4 starts to bend and becomes the starting point of the bending deformation.

[0045] When the one-way fastener T of the fourth embodiment is inserted into the through holes 5K, 6K of the plate materials 5, 6 to be fastened (see FIG. 8(a)) as in FIG. 3(a), and the shank 1B of the bolt 1 is supported so as not to rotate by a tightening tool (not shown) and the nut 2 is rotated, the bolt 1 screwed into the female threaded portion 2N of the nut 2 moves forward as shown in FIG. 8(b). At this time, the sleeve 4 receives a compressive force in the axial direction, and the first groove 12A and the second groove 12B of the sleeve 4 are plastically deformed. At this time, when the first groove 12A moves outward in the radial direction, the front side portion 4d of the through hole 6K on the inner side of the first groove 12A also moves outward in the radial direction. Then, the outer peripheral surface portion 4G on the near side abuts against the inner edge 6A of the through hole 6, and the outer peripheral surface portion 4G cannot move radially outward any further, so that the outer peripheral surface portion 4G becomes the starting point of bending deformation, and is bent into a substantially V-shape consisting of the first side 4C and the second side 4D (see FIG. 8(b)). When the nut 2 is further rotated, the bending deformation at the outer peripheral surface portion 4G on the near side progresses, and the outer peripheral surface 4H of the first side 4C abuts against the inner end surface 6T of the inner fastened plate material 6 as shown in FIG. 9(a). By continuing to rotate the nut 2, the first side 4C abutting against the inner end surface 6T of the inner fastened plate material 6 is pulled out radially outward by the longer second side 4D, and the effect of preventing the one-way fastener T from coming off the fastened plate materials 5, 6 can be enhanced (see FIG. 9(b)). Furthermore, the lower portion 4E of the sleeve 4 is pulled toward the back of the through holes 5K, 6K, and the front end face 4A of the sleeve 4, which is the fastening side, moves away from the front edge 5A of the fastened plate material 5 toward the back as the bending deformation progresses, so that the axial compressive force generated by fastening the bolt 1 and nut 2 can be reliably applied between the nut 2 and washer 3 and the substantially V-shaped bent and deformed portion (a portion bulging outward in the radial direction, also called a bulge) 8. This allows the fastened plate materials 5, 6 to be reliably fastened with the one-way fastener T.

[0046] Incidentally, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0047] In the above embodiment, the groove formed in the sleeve 4 is substantially V-shaped, but it may be substantially U-shaped, substantially arc-shaped, substantially trapezoidal, or any other shape. Also, the number of grooves may be any number as long as it is at least two.

[0048] In the above embodiment, the groove formed in the sleeve 4 is the weakened portion, but the weakened portion may be formed by forming a thin-walled portion by partially reducing the thickness of the sleeve 4. Also, the weakened portion may be formed by partially reducing the hardness.

[0049] In addition, in the above embodiment, the fastened plate materials 5, 6 are fastened with the head 1A of the bolt 1 positioned at the rear side and the nut 2 positioned at the front side, but the fastened plate materials 5, 6 may also be fastened with the head 1A of the bolt 1 positioned at the front side and the nut 2 positioned at the rear side. [Explanation of symbols]

[0050] 1...Bolt, 1A...Head, 1B...Shaft, 1N...Male threaded portion, 1a...End face on shaft side, 2...Nut, 2B...Upper end face, 2N...Female threaded portion, 3...Washer, 3K...Through hole, 3A...Second surface, 3B...First surface, 4...Sleeve, 4A...Front end face, 4B...Rear end face, 4C...First side, 4D...Second side, 4E...Lower portion, 4G...Part of outer periphery, 4H...Outer periphery, 4c...End, 4d...Part 4e...lower part, 5,6...plate material to be fastened, 5A...front edge, 5K,6K...through hole, 5T...front edge, 6A...back edge, 6T...back edge, 7,10,11,12...weak part, 7A, 7B,7C,7D...groove, 9...broken part, 9A...grip part, 9B...broken groove, 10A,10B,10C,10D...groove, 11A,11B,11C...groove, 12A,12B...groove, T...one-way fastener

Claims

1. A bolt capable of passing through a through hole formed in a plate material to be fastened; A nut screwed onto the shank of the bolt; a sleeve that is provided on the shank of the bolt so as to cover the outer periphery of the shank and that can pass through a through hole of the plate to be fastened while being provided on the shank; The sleeve is configured to be deformed by receiving a compressive force in an axial direction as the bolt and the nut are fastened together, The deformation is a deformation in which a partial region of the sleeve in the axial direction is bent and deformed into a substantially V-shape in a cross-sectional shape along the axial direction, away from the bolt in the radial direction outward, Of the two sides constituting the bent and deformed substantially V-shape, a first side closer to the fastened plate material is shorter than a second side farther from the fastened plate material, A one-way fastening device in which the end face on the front side of the sleeve, which is the side to be tightened, is axially aligned with the front edge of the fastened plate material before tightening, and moves away from the front edge to the rear side as the bending deformation progresses.

2. 2. The one-way fastener according to claim 1, wherein the sleeve has a weak portion having a strength with respect to the compressive deformation weaker than other portions in the axial direction, the bending deformation occurs due to plastic deformation of the weak portion, and after the bending deformation begins, the position of the end of the first side closer to the fastened plate material is in the same axial position as the rear edge of the through hole.

3. 2. The one-way fastener of claim 1, wherein the sleeve has a weak portion whose strength with respect to the compressive deformation is weaker than other portions in the axial direction, the bending deformation occurs due to plastic deformation of the weak portion, and after the bending deformation begins, the position of the end of the first side that is closer to the fastened plate material is located near the rear edge of the through hole and further inside the through hole than the rear edge.

4. The one-way fastener according to claim 1 , wherein the bending deformation of the sleeve starts at a position where an outer circumferential surface of the sleeve abuts against a rear end edge of the through hole after the bending deformation starts.

5. A one-way fastener as described in any one of claims 1 to 4, wherein the bolt is positioned so that its head is located at the rear side of the fastened plate material, and the radial dimension of the head is formed smaller than the hole diameter of the through hole.

6. 6. The one-way fastener according to claim 5, wherein the bolt further comprises a breaking portion at a front end portion of the plate material to be fastened, the breaking portion being supported so as to immobilize the bolt in the circumferential direction during the tightening, and being broken relative to the shank of the bolt and removed after tightening of the nut is completed.

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