Existing nut loosening preventive device

Abstract

To provide a loosening prevention nut capable of generating an excellent loosening prevention action for an existing general nut.SOLUTION: A loosening prevention nut includes a body part 3 having a screw hole 2 screwed with a bolt B above an existing nut N, and a cylindrical part 4 externally fitted to the upper end of the existing nut N in an integrated manner. An inner peripheral surface of the cylindrical part 4 is composed of a tapered surface whose diameter increases gradually toward the lower part, and becomes eccentric with respect to the screw hole 2 so that the inner periphery of the cylindrical part 4 interferes with the hexagonal corner part upper end of the existing nut N in a part in a circumferential direction, and pressing force orthogonal to an axial direction is generated in the existing nut N.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an anti-loosening nut used as a device for preventing loosening of an existing nut fastened to a bolt. [Background technology]

[0002] The applicant of the present application has been developing a hard lock nut ("Hard Lock" is a trademark of the applicant of the present application) that is an anti-loosening nut that exhibits a high level of anti-loosening function, and has disclosed these in, for example, Patent Documents 1 to 4 described below.

[0003] This hard lock nut is composed of a lower nut having a threaded hole that screws onto a screw shaft, and an upper nut having a threaded hole that screws onto the screw shaft.

[0004] Either the lower nut or the upper nut is provided with a convex portion in the shape of a truncated cone that protrudes axially toward the other nut. The convex portion has a tapered outer peripheral surface with a predetermined taper angle that gradually decreases in diameter toward the tip side. The screw hole passes through the convex portion along the axial direction. A nut with a convex portion is called a "convex nut."

[0005] The other nut has a recess into which the protrusion fits. The recess has a tapered inner circumferential surface with a taper angle that matches the taper angle of the outer circumferential surface of the protrusion, preferably the same taper angle. The screw hole of the other nut opens to the bottom surface of the recess. A nut having a recess is called a "concave nut."

[0006] The Hardlock Nut has an eccentric fit between a convex portion and a concave portion, which creates a stress state just as if a wedge had been driven between the outer periphery of the screw shaft and the inner periphery of the screw hole in the nut, and this wedge action provides a powerful anti-loosening effect.

[0007] The eccentric fit between the convex portion and the concave portion is achieved by forming the outer peripheral surface of the convex portion eccentrically with respect to the screw hole of the convex nut, or by forming the inner peripheral surface of the concave portion eccentrically with respect to the screw hole of the concave nut. When the outer peripheral surface of the convex portion is eccentric, the inner peripheral surface of the concave portion and the screw hole of the concave nut are made concentric. On the other hand, when the inner peripheral surface of the concave portion is eccentric, the outer peripheral surface of the convex portion and the screw hole of the convex nut are made concentric.

[0008] In a Hardlock Nut, when the convex portions and concave portions of the upper and lower nuts are screwed onto the screw shaft, they are eccentrically fitted together, and the outer peripheral surface of the convex portion and the inner peripheral surface of the concave portion interfere with each other along part of the circumferential direction so that a pressing force is generated in each of the upper and lower nuts in the eccentric direction. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6762591 [Patent Document 2] JP 2016-125622 A [Patent Document 3] JP 2016-133136 A [Patent Document 4] JP 2002-195236 A [Patent Document 5] JP 2011-174600 A Summary of the Invention [Problem to be solved by the invention]

[0010] Replacing existing standard nuts with Hardlock Nuts can provide excellent anti-loosening effects, but in cases where there are a huge number of existing nuts, the work of removing the existing nuts is time-consuming and the total work time is long, so they have sometimes been replaced with simple anti-loosening clips such as those shown in JP 2011-174600 A (Patent Document 5). However, users are demanding a locking device that can apply the principles of the hard lock nut to prevent loosening of existing standard nuts. [Means for solving the problem]

[0011] The present invention is an anti-loosening nut that prevents an existing nut fastened to a bolt from loosening, and comprises a main body portion having a threaded hole that screws onto the bolt above the existing nut, and a cylindrical portion that fits onto the upper end of the existing nut, the inner surface of the cylindrical portion being configured as a tapered surface that gradually becomes larger in diameter as it extends downward, and is eccentric with respect to the threaded hole so that, at a portion of the circumferential direction, the inner circumference of the cylindrical portion and the outer circumference of the existing nut interfere with each other, generating a pressing force on the existing nut perpendicular to the axial direction.

[0012] According to the present invention, when the anti-loosening nut of the present invention is fastened to a bolt above an existing nut (ordinary nut) that is fastened to the bolt, the outer circumference of the existing nut and the inner circumference of the main body interfere with each other in part of the circumferential direction, generating a pressing force perpendicular to the axial direction of the existing nut, and as a reaction force, a pressing force in the opposite direction is generated on the anti-loosening nut. The pressing forces generated by the wedge action on the existing nut and the anti-loosening nut provide an excellent anti-loosening effect to the existing nut and the anti-loosening nut.

[0013] The screw hole may be provided with an opening at the bottom, and the main body may have a top portion that closes an upper end of the screw hole. This can prevent rainwater or the like from entering the screw hole, and can prevent corrosion of the nut and bolt.

[0014] Preferably, the inclination angle θ of the tapered surface constituting the inner peripheral surface of the cylindrical portion with respect to the axis is 15° or more, and more preferably 20° or more. With this, the large inclination angle of the tapered surface can absorb relatively large manufacturing errors in the outer peripheral shape of the existing nut and dimensional changes due to aging deterioration, corrosion, etc., and the above-mentioned axial pressing force can be reliably generated.

[0015] In the present invention, the existing nut is a hexagonal nut, and the inner circumferential surface of the cylindrical portion interferes with the upper end of a corner of the hexagonal shape of the hexagonal nut.

[0016] The outer periphery of the locking nut body may be cylindrical or frusto-conical. This prevents the locking nut from being tampered with by a general spanner or box wrench. The locking nut member can be fastened using a special tool that fits the outer periphery of the locking nut. Effect of the Invention

[0017] According to the present invention, it is possible to provide a locking nut that can easily and quickly provide an excellent locking effect on an existing nut. [Brief description of the drawings]

[0018] [Figure 1] 1 is a vertical cross-sectional view showing a state before the locking nut according to one embodiment of the present invention is attached. FIG. [Diagram 2] FIG. 4 is a vertical cross-sectional view of the locking nut in an attached state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1 and 2 show a locking nut 1 according to one embodiment of the present invention, which is intended to prevent loosening of an existing nut N by attaching it to an existing fastener consisting of an existing nut N fastened to a bolt B and the bolt B. The existing nut N is a general nut conforming to public standards, and is typically a hexagonal nut.

[0020] The locking nut 1 is integrally provided with a main body 3 having a screw hole 2 that screws onto a bolt B above the existing nut N, and a cylindrical part 4 that fits onto the upper end of the existing nut N. The outer peripheral surface shape of the main body 3 may be any suitable one, but for example, it may be a hexagonal nut shape similar to that of the existing nut N. The inner peripheral surface of the cylindrical part 4 is formed of a tapered surface that gradually increases in diameter as it approaches the bottom, and is eccentric with respect to the screw hole 2 so that a pressing force perpendicular to the axial direction is generated on the existing nut N by interference between the inner peripheral surface of the cylindrical part 4 and the upper end of the hexagonal corner of the existing nut N in a part of the circumferential direction (left side in the figure). As a reaction force of the pressing force generated on the existing nut N, a pressing force is generated in the opposite direction on the locking nut 1. The top part 3a of the main body 3 is closed, and the screw hole 2 is provided in a downwardly opening shape.

[0021] According to the locking nut 1 of this embodiment, by additionally fastening the existing nut N to the upper end of the fastened bolt B, a wedge action is generated by the eccentric fit between the inner peripheral surface of the cylindrical portion 4 and the outer periphery of the upper end of the existing nut N, and large opposing horizontal pressing forces are generated on the existing nut N and the locking nut 1, thereby providing an excellent locking function. Also, by blocking the upper end of the screw hole 2 with the apex 3a, rainwater and the like can be prevented from entering the screw hole 2, and corrosion and the like can be prevented.

[0022] The present invention is not limited to the above-described embodiment, and the design can be modified as appropriate. [Explanation of symbols]

[0023] 1 Locking nut 2 Screw holes 3 Main body 3a top 4 Cylindrical section

Claims

1. A locking nut that prevents an existing nut fastened to a bolt from loosening, A body portion having a screw hole that screws into the bolt above the existing nut, and a cylindrical portion that fits onto the upper end of the existing nut, The inner peripheral surface of the cylindrical portion is configured as a tapered surface whose diameter gradually increases toward the bottom, and is eccentric with respect to the screw hole so that the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the existing nut interfere with each other in a part of the circumferential direction, thereby generating a pressing force perpendicular to the axial direction on the existing nut. Anti-loosening nut.

2. The locking nut according to claim 1, An anti-loosening nut, wherein the screw hole is open downward, and the main body portion has a top portion that closes the upper end of the screw hole.

3. The locking nut according to claim 1, A locking nut, wherein the inclination angle of the tapered surface constituting the inner peripheral surface of the cylindrical portion with respect to the axis is 15° or more.

4. The locking nut according to claim 1, An anti-loosening nut, wherein the inclination angle of the tapered surface constituting the inner peripheral surface of the cylindrical portion with respect to the axis is 20° or more.

5. The locking nut according to claim 1, The existing nut is a hexagonal nut, and the inner surface of the cylindrical portion interferes with the upper end of a hexagonal corner of the hexagonal nut.

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