JP2003294021A - Lock nut - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lock nut in which a looseness preventive function is given to a tightening nut by plastically deforming a female screw of the tightening nut, capable of preventing the tightening nut from loosening though the lock nut is loosened with simple tightening works. <P>SOLUTION: The lock nut 1 is provided for looseness prevention of the tightening nut by tightening the lock nut on the tightening nut 2 engaged with a male screw 20. The lock nut is made from a material having hardness greater than that of the material of the tightening nut. A projected portion 13 provided for plastically deforming the female screw of the tightening nut is formed on a peripheral edge of a screw hole located on an end face of the lock nut at an axial direction by pressing the pointed head to the peripheral edge of the screw hole of the tightening nut. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for fastening various types of machinery and equipment such as steel frames for construction, and more particularly to a final fastening screwed into a male screw portion (bolt or the like). The present invention relates to a lock nut that is tightened from above to prevent loosening of a final tightening nut. 2. Description of the Related Art Conventionally, bolts and nuts as fastening means may be gradually loosened by external force such as vibration, and various means have been proposed as means for preventing such loosening of the nut. ing. Among these, a fastening structure using a double nut using two nuts of the same size (same outer diameter) is well known as a typical locking means. This double nut tightens the other nut (locking nut) from one nut (final tightening nut) screwed into the male screw part (bolt, etc.). Both nuts are prevented from loosening by the action of tightening. [0003] In such a double nut, it is necessary to tighten the two nuts so that the two nuts are securely brought into close contact with each other. For this reason, while tightening one lock nut, turn the other fully tightened nut in the loosening direction. As a result, a complicated work such as firmly tightening both nuts together is forced. Further, if the lock nut is loosened, the function as a double nut is lost, and there is a problem that the loosening of the final tightening nut cannot be prevented. Conventionally, there is known a lock nut in which a projection is provided on a peripheral portion of a screw hole on an axial end surface (see Patent Documents 1 and 2). [0005] [Patent Document 1] Japanese Patent Application Laid-Open No. H10-61645 [Patent Document 2] Japanese Patent Application Laid-Open No. H11-315820 [0006] When such a conventional lock nut is tightened to a nut for final tightening, the periphery of the screw hole is reduced. The projections protruding from the part are crushed and are entangled in the threaded part of the female screw part and the male screw part (bolt etc.) of the nut for final tightening.
Thereby, the rotation of the nut for final tightening is restricted, and the nut is prevented from rotating. As described above, the conventional lock nut is not a protrusion for plastically deforming the female screw portion of the final tightening nut. In particular, since the conventional lock nut functions only when the protrusion is crushed, the hardness of the material must be equal to or less than the hardness of the material of the nut for final fastening. Further, there is a problem that the projection cannot be reused as a lock nut because the projection is crushed. SUMMARY OF THE INVENTION [0007] The present invention has been made to solve the above-described problems, and a conventional art in which both nuts are prevented from loosening by the action of tightening the nuts together. Unlike the double nut of this item, the female screw part of the final tightening nut is plastically deformed by the lock nut, so that the final tightening nut itself has a function of preventing loosening, simplifying the tightening work. It is another object of the present invention to provide a locking nut that can prevent the final tightening nut from being loosened even if the locking nut is loosened. [0008] In order to solve the above-mentioned problems, the lock nut of the present invention is tightened from above on a final tightening nut screwed into a male screw portion, thereby providing a final tightening nut. A lock nut for preventing loosening of a nut, formed of a material having a hardness higher than the hardness of the material of the nut for final tightening. The protrusion is formed such that the distal end portion is pressed against the periphery of the hole to plastically deform the female screw portion of the nut for final tightening. The locking nut of the present invention is used by tightening from above a final tightening nut screwed into a male screw portion such as a bolt, that is, such that a protrusion faces the final tightening nut. Screw into the screw. When the locking nut is screwed in this way, the projection is formed at the periphery of the screw hole, and the tip of the projection comes into contact with the periphery of the screw hole of the nut for final tightening. When the locking nut is further tightened, the tip of the protrusion is pressed against the peripheral edge of the screw hole of the final tightening nut, and the pressing force causes the female screw portion of the final tightening nut to be plastically deformed. . Due to the plastic deformation of the female screw portion, the clearance between the female screw portion and the male screw portion is lost, and the female screw portion and the male screw portion come into close contact with each other. The tightening nut will have its own locking function. Therefore, even if the locking nut is loosened, the final tightening nut itself can prevent the loosening. Also, unlike the conventional case, the lock nut and the final tightening nut are in close contact with each other,
A complicated operation such as tightening both nuts is not required, and loosening of the final tightening nut can be prevented by a simple operation of simply tightening the lock nut. In particular, in the present invention, as a means for plastically deforming the female screw portion of the nut for final tightening by the pressing force accompanying the tightening of the lock nut, the hardness of the material of the lock nut is used for the final tightening. The hardness is higher than the hardness of the nut material. Therefore, even if the tip of the projection bites into the final fastening nut, the projection is not crushed, and the female screw portion of the final fastening nut can be securely plastically deformed. Embodiments of the present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is a sectional view of a double nut structure using a lock nut according to a first embodiment of the present invention, FIG. 2 is a bottom view of the lock nut, and FIG. 3 is an enlarged sectional view of the lock nut. As shown in FIGS. 2 and 3, the lock nut 1 has a nut body 1a formed in a hexagonal nut shape having a female screw portion 11 formed on an inner peripheral surface of a screw hole 10.
Four single-width protrusions 13 are formed at the same interval along the periphery of the screw hole on one axial end surface (bottom surface) 12 of the nut main body 1a. The other axial end surface (upper surface) 14
May be formed on a flat surface or a similar protrusion may be formed. Further, the shape of the nut body 1a is not limited to a hexagonal nut shape, but may be formed in a square nut shape or the like, or the steel plate may be formed by pressing and drawing a steel plate. Each of the projections 13 is integrally formed with the nut body 1a at the periphery of the screw hole on the axial end face 12, and has a side surface formed in a convex arc shape as shown in FIG.
Its cross-sectional shape is formed in a square shape. The number of protrusions 13 is not limited to four in the embodiment, but may be one, or two, three, five, six, or the like. The side shape of the protrusion 13 is shown in FIG.
May be rectangular as shown in FIG.
It can be formed in a triangular shape as shown in FIG. 5, a chevron shape as shown in FIG. 6, a semicircular shape as shown in FIG. 7, and a circular arc shape as shown in FIG. The lock nut 1 is used as a double nut together with a final tightening nut 2 as shown in FIG. In this case, the material of the final tightening nut 2 is generally a mild steel, but the lock nut 1 of the present embodiment is formed of a material having a higher hardness than the material of the final tightening nut 2. Have been. As a specific material, steel (SWCH8 to 10, SS400, S45C
Etc.), high tension steel, stainless steel (SUS304)
Etc.), alloy steel (such as SCM435), titanium, and other synthetic resins such as aluminum, copper, hard PVC, and polycarbonate, as long as the hardness is higher than the material of the nut 2 for final fastening. Therefore, as shown in FIG. 1, after the final tightening nut 2 is screwed into the male screw portion 40 of the bolt 4 passed through the members to be fastened 3, the members 3, 3 are fastened. The locking nut 1 is screwed into the male screw portion 40 such that the projection 13 faces the final tightening nut 2. As a result, the protrusion 1
3 comes into contact with the peripheral edge of the screw hole of the nut 2 for final tightening, but when the nut 1 for locking is further tightened, the distal end of the projection 13 becomes the peripheral edge of the screw hole of the nut 2 for final tightening. The female screw portion 20 can be plastically deformed at the screw hole opening of the final tightening nut 2 by the pressing force. Thus, the female screw portion 20
Is plastically deformed, the clearance between the female screw portion 20 and the male screw portion 40 is lost, and the female screw portion 20 and the male screw portion 4 are removed.
0 strongly adheres, and the rotational resistance of the final tightening nut 2 increases accordingly, so that the final tightening nut 2 itself has a function of preventing loosening. Therefore, even if the lock nut 1 is loosened, the final tightening nut 2 itself can prevent loosening, and
The loosening of the final tightening nut 2 can be prevented by a simple operation of simply tightening the lock nut 1. In particular, the female screw portion 20 of the final tightening nut 2
As a means for plastically deforming the lock nut 1 by a pressing force accompanying the tightening of the lock nut 1, the hardness of the material of the lock nut 1 is set to be higher than the hardness of the material of the final tightening nut 2. Therefore, even if the tip of the projection 13 bites into the nut 2 for final fastening, the projection 13 is not crushed, and the female screw portion 20 of the nut 2 for final fastening can be reliably plastically deformed. Next, FIG. 9 is a bottom view showing the lock nut of the second embodiment, and FIG. 10 is an enlarged sectional view of the lock nut. The lock nut 1 has three long protrusions 13 formed at the same interval along the periphery of the screw hole on one axial end surface (bottom surface) 12 of the nut main body 1a.
Note that the other axial end surface (upper surface) may be formed as a flat surface, or a similar protrusion may be formed. Further, each of the protrusions 13 is provided integrally with the nut body 1a at the periphery of the screw hole of the axial end face 12, and the side surface is formed in a convex arc shape as shown in FIG. The cross-sectional shape is square. The number of protrusions 13 is not limited to three in the embodiment, but may be one, two, four, five or the like. Further, the side surface shape of the protrusion 13 can be formed in a square shape as in the first embodiment, and the cross-sectional shape thereof is triangular as shown in FIGS. 5, 6, 7 and 8. , A chevron, a semicircle, and a tip arc. FIG. 11 is a bottom view showing a lock nut according to a third embodiment, and FIG. 12 is a sectional view of the lock nut. The locking nut 1 is formed integrally with an annular protrusion 13 along the periphery of the screw hole on one axial end surface (bottom surface) 12 of the nut body 1a. Note that the other axial end surface (upper surface) may be formed as a flat surface, or a similar protrusion may be formed. Further, the cross-sectional shape of each of the protrusions 13 can be formed in a rectangular shape as in the first embodiment, or can be formed in a triangular shape or a chevron shape as shown in FIGS. , A semicircular shape, or a circular arc shape at the tip. Further, the tip surface of the projection 13 can be formed in a wave shape, a tooth shape, a saw blade shape, or the like. Next, FIG. 13 is a bottom view showing a lock nut of a fourth embodiment, and FIG. 14 is a sectional view of this lock nut. The locking nut 1 is formed along the periphery of the screw hole on one axial end surface (bottom surface) 12 of the nut main body 1a.
The hemispherical projections 13 are integrally formed at the same interval. Note that the other axial end surface (upper surface) may be formed as a flat surface, or a similar protrusion may be formed. Also, protrusion 1
The number of 3 is not limited to four in the embodiment, and may be one,
Two, three, five, six, seven, eight, ten, etc. can be formed. As described above, according to the lock nut of the present invention, the female screw portion of the final tightening nut can be plastically deformed by tightening the lock nut. The locking nut itself can have a locking function. Therefore, even if the locking nut is loosened, the final tightening nut itself can prevent the loosening. Also, unlike the past, complicated work such as tightening both nuts so that the lock nuts and the final tightening nuts are in close contact with each other is not necessary, and the final tightening is simply performed by simply tightening the lock nuts. Can be prevented from loosening. In particular, since the hardness of the material of the lock nut is higher than the hardness of the material of the final tightening nut, the protrusion is not crushed, and the female screw portion of the final tightening nut is securely plasticized. Can be deformed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a double nut structure using a lock nut according to a first embodiment of the present invention. FIG. 2 is a bottom view of the lock nut. FIG. 3 is an enlarged sectional view of the locking nut. FIG. 4 is an enlarged sectional view showing another example of a protrusion formed on a lock nut. FIG. 5 is an enlarged half sectional view showing another example of a protrusion formed on a lock nut. FIG. 6 is an enlarged half sectional view showing another example of a protrusion formed on a lock nut. FIG. 7 is an enlarged half sectional view showing another example of a protrusion formed on a lock nut. FIG. 8 is an enlarged sectional view showing another example of a protrusion formed on a lock nut. FIG. 9 is a bottom view of a lock nut according to a second embodiment of the present invention. FIG. 10 is an enlarged sectional view of the locking nut. FIG. 11 is a bottom view of a lock nut according to a third embodiment of the present invention. FIG. 12 is a sectional view of the lock nut. FIG. 13 is a bottom view of a locking nut according to a fourth embodiment of the present invention. FIG. 14 is a sectional view of the lock nut. [Description of Signs] 1 Locking Nut 1a Nut Main Body 10 Screw Hole 11 Female Thread 12 Axial End Face 13 Protrusion 2 Final Tightening Nut 20 Female Thread 3 Fastened Member 4 Bolt 40 Male Thread

Claims (1)

Claims: 1. A locking nut which is adapted to prevent loosening of a final tightening nut by tightening the final tightening nut screwed onto a male screw portion, the final tightening being performed. Is formed of a material having a hardness higher than the hardness of the material of the nut for tightening. The tip of the nut is pressed against the periphery of the screw hole on the axial end face, and the female part of the nut for final tightening is pressed. A locking nut having a protrusion for plastically deforming a screw portion.