JP2015052369A - Bolt / nut locking structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bolt / nut loosening prevention structure capable of substantially improving the loosening prevention performance by guaranteeing the strength of a bolt male screw formed with a right screw and a left screw. A male screw 10C is formed on the surface of a bolt shaft portion 10A, and the male screw is a right-handed screw half disposed alternately at positions opposite to each other with respect to a straight line extending parallel to the bolt axis line on the surface of the bolt shaft portion. 10C-1 and left screw half 10C-2. The right screw half and left screw half are formed by rolling into a triangular screw shape so that the metal flow is continuous, The screw nut 11 and the left screw nut 12 are screwed into a double nut shape to prevent loosening. [Selection] Figure 1

Description

  The present invention relates to a bolt / nut loosening prevention structure, and more particularly to a structure capable of improving the loosening prevention performance by guaranteeing the strength of a bolt male screw.

  The method of fastening using bolts is adopted in many structures. The bolt is simply screwed and tightened to the female screw formed on the member to be fastened, or simply screwed into the nut on the back side through the member to be fastened and tightened. There is a concern that loosening of the fastening may occur due to initial looseness due to roughness, waviness or shape error of the contact portion, return rotation of the nut due to static fluctuation or dynamic fluctuation of the axial force, and the like.

  On the other hand, the bolt male screw is provided with the right and left screw halves alternately and alternately, and the right screw nut and the left screw nut are overlapped in a double nut shape and screwed together to prevent loosening. A loosening prevention structure has been proposed (Patent Document 1).

Japanese Patent No. 4663813

  However, in the loosening prevention structure described in Patent Document 1, the female screw of the nut meshes with about 1/2 of the screw thread in the circumferential direction of the male screw of the bolt, so a part of the male screw must receive a load from the female screw. There is a concern that the thread of the screw will be damaged.

  In view of such problems, an object of the present invention is to provide a bolt / nut loosening prevention structure that can guarantee the strength of a male screw and improve the loosening prevention performance.

  Therefore, in the bolt / nut loosening prevention structure according to the present invention, the bolt shaft portion is inserted into the insertion hole of the member to be joined, the nut is screwed into the bolt shaft portion, and a washer is provided between the nut and the member to be joined. In the bolt and nut fastening structure that is interposed and tightened, a male screw is formed on the surface of the bolt shaft, and the male screw is positioned opposite to a straight line that extends parallel to the bolt axis on the surface of the bolt shaft. The right screw half and the left screw half are alternately formed in a triangular screw shape so that the metal flow is continuous, and the bolt The male screw is characterized in that a right screw nut and a left screw nut are screwed into a double nut shape to prevent loosening.

  One of the features of the present invention is that a right screw and a left screw of a bolt male screw are formed into a triangular screw shape so that the metal flow is continuous by rolling, and a right screw nut and a left screw nut are formed into a double nut shape on the bolt male screw. It is in the point which made it screw.

  As a result, the metal flow of the right screw and left screw of the bolt male screw can ensure a high strength continuously, so that the female screw of the nut is engaged with about 1/2 of the screw thread in the circumferential direction of the male screw, and a part of the male screw In the case where the load from the female screw is received, the possibility that the thread of the male screw of the bolt is damaged can be reduced.

  By the way, of the right screw nut and the left screw nut of the bolt male screw, on the seat surface of the washer side nut in contact with the washer surface, the inclined surface that allows the bolt to rotate in the screwing direction and the rotation of the bolt in the screwing direction are prevented. When a plurality of meshing portions having rotation preventing portions are formed side by side in the circumferential direction of the washer side nut seat surface, an elastically deformable locking piece portion having a side hook shape is provided on the washer surface. When the bolt is rotated in the screwing direction, it is guided by the inclined surface of the nut engaging portion and elastically deformed to overcome the rotation blocking portion, and when the bolt is rotated in the screwing direction, the nut is engaged. It can be made to contact with the rotation prevention part of the part.

  As a result, the bolt or the nut smoothly moves slightly beyond the rotation prevention portion of the nut engagement portion by the elastically deforming the locking piece portion of the washer guided by the inclined surface of the nut engagement portion in the screwing direction of the bolt. Although the bolt can be rotated, the locking piece portion of the washer abuts against the rotation blocking portion of the meshing portion of the nut in the screwing direction of the bolt and is prevented from rotating, so that the bolt and nut can be prevented from loosening.

  When such a configuration is adopted, a locking groove is formed in the bolt shaft portion extending in the axial direction, and the locking groove is fitted into the inner edge of the bolt shaft insertion hole of the washer so that the washer is attached to the bolt shaft portion. It is preferable to form a locking projection that stops the rotation.

  Accordingly, the washer can be prevented from rotating with respect to the bolt shaft portion by the locking groove of the bolt shaft portion and the locking projection of the washer, and the loosening prevention performance depends on, for example, the friction between the washer and the member to be joined. The result is that the washer can be reliably prevented from rotating with respect to the bolt shaft, so that the bolt and nut can be reliably prevented from loosening.

  Further, of the right screw nut and the left screw nut, the nut on the washer side has a frustoconical fitting protrusion on the opposite side of the washer, and the fitting protrusion is fitted on the washer side on the other nut. By forming the concave conical recess, the effect of preventing the bolts and nuts from loosening can be further improved.

  In this case, the frustoconical shapes of the fitting protrusion and the fitting recess can be decentered from each other. Thereby, when the double nut is tightened, the frustoconical shapes of the fitting protrusion and the fitting recess are firmly pressed against each other, and the loosening prevention effect can be further improved.

It is sectional drawing which shows preferable embodiment of the bolt / nut loosening prevention structure of this invention. It is a figure which shows a bolt axial part and a washer in the said embodiment. It is a schematic perspective view which shows the volt | bolt in the said embodiment. It is a schematic perspective view which shows the nut in the said embodiment. It is a figure which shows the latching piece part in the said embodiment. It is a figure which shows the relationship between the right-hand screw and left-hand screw of the volt | bolt male screw in the said embodiment. It is a figure which shows typically the processing method of a volt | bolt male screw in the said embodiment. It is a figure which shows the rolling flat die | dye used for the process of a volt | bolt external thread in the said embodiment.

  Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 to 6 show a preferred embodiment of a bolt and nut locking structure according to the present invention. In the figure, the members to be joined 14 and 15 are fastened and joined by a bolt 10, a right screw nut 11, a left screw nut 12 and a washer 13.

  The bolt 10 includes a hexagonal head and a shaft portion 10A. A male screw 10C is formed on the shaft portion 10A, and a right screw nut 11 and a left screw nut 12 are overlapped and screwed into a double nut shape. It has become. The right screw nut 11 on the washer side has a frustoconical fitting protrusion 11D on the opposite side of the washer, and the other left screw nut 12 has a frustoconical fitting recess 12D on the washer side. The center line of the truncated conical shape of the concavity 12D is eccentric with respect to the center axis of the bolt shaft part 10A and the center line of the frustoconical shape of the fitting protrusion 11D. The fitting projection 11D of the nut 11 is fitted, and the inner surface of the frustoconical shape of the fitting recess 12D is strongly pressed against the outer surface of the frustoconical shape of the fitting projection 11D.

  As shown in FIGS. 3 and 6, the male male screw 10 </ b> C has right screw halves 10 </ b> C− alternately arranged at positions opposite to each other with respect to a straight line extending parallel to the bolt axis on the surface of the bolt shaft 10 </ b> A. 1 and a left screw half 10C-2.

  The right screw half 10C-1 and the left screw half 10-2 are formed into a triangular screw shape by rolling, as shown in FIG. 7, using rolling flat dies 30, 31 shown in FIG. The metal flow is continuous, and the right screw half 10C-1 and the left screw half 10-2 are processed so that the thread height gradually decreases from the center to the circumferential direction as shown in FIG. ing.

  A plurality of engaging portions 11A are formed in a circumferential direction on the seat surface of the nut 11 on the washer 13 side, and each of the engaging portions 11A has an inclined surface 11B and a bolt 10 that allow the bolt 10 to rotate in the screwing direction. It is comprised from the step part (rotation prevention part) 11C which blocks | prevents rotation of the screwing direction.

  The washer 13 is formed into a flat disk shape using a metal plate, and a fitting recess 13A is formed on the surface of the washer 13, and the fitting recess 13A has an elastically deformable locking piece having a side hook shape. When the portion 13B is fitted and the locking piece 13B is guided by the inclined surface 11B of the meshing portion 11A of the nut 11 and elastically deformed with respect to the rotation of the bolt 10 in the screwing direction, the meshing portion 11A of the nut 11 is deformed. The locking piece 13B is brought into contact with the stepped portion 11C of the engaging portion 11A of the nut 11 with respect to the rotation of the bolt 10 in the screwing direction over the stepped portion 11C.

  A pair of locking grooves 10B are formed in the bolt shaft portion 10A so as to extend in the axial direction with an angular interval of 180 ° from each other, and a pair of locking protrusions 13C are formed on the inner edge of the bolt insertion hole of the washer 13. Are formed with an angular interval of 180 ° from each other, and the locking projection 13C is fitted into the locking groove 11B, so that the washer 13 is prevented from rotating with respect to the bolt shaft portion 10A.

  8A shows a side surface of the movable die, FIG. 8B shows a plane of the movable die, FIG. 8C shows a side surface of the fixed die, and FIG. 8B shows a plane of the fixed die. In the figure, 30 is a fixed die, 31 is a movable die, 30B is a screw crest and pitch alignment position, 31B is a screw trough bottom and pitch alignment position, and 30A and 30B are finish rolling regions. In addition, the rolling flat dies 30 and 31 are formed with an electric discharge machining and a horn finish so as to roll the right and left threads of the above-described shape.

  When joining the members 14 and 15 to be joined, as shown in FIG. 1, the bolt shaft portion 10A is inserted into the insertion hole of the members 14 and 15 and the washer 13, and the nuts 11 and 12 are screwed into the male screw 10C. Then, the locking protrusion 13C of the washer 13 is fitted into the locking groove 10B of the bolt shaft portion 10A, and the washer 13 is prevented from rotating with respect to the bolt shaft portion 10A.

  When the preparation is completed, the bolt head is held with an appropriate tool, and the nuts 11 and 12 are rotated with an appropriate tool to be sequentially screwed. When the periphery of the seat surface of the nut 11 comes into contact with the washer 13, the locking piece portion 13 </ b> C of the washer 13 comes into contact with the meshing portion 11 </ b> A of the nut 11.

  Then, the locking piece 13C of the washer 13 is slidably brought into contact with the inclined surface 11B of the engaging portion 11A of the nut 11 and is elastically deformed to overcome the stepped portion 11C of the engaging portion 11A. The nut 11 is tightened by screwing with respect to 11A, and the lower surface of the washer 13 and the seat surface of the nut 11 are brought into close contact with each other.

  When the right screw nut 11 is tightened, the left screw nut 12 is screwed onto the bolt male screw 10 </ b> C and tightened in the same manner as the nut 11. Then, the fitting projection 11D of the right screw nut 11 is fitted into the fitting recess 12D of the left screw nut 12, but the frustoconical centerlines of the fitting recess 12D and the fitting projection 11D are eccentric to each other. Therefore, the outer surface of the fitting protrusion 11D is strongly pressed against the inner surface of the fitting recess 12D.

  When the nut 11 tries to rotate in the loosening direction in this state, the locking piece portion 13C of the washer 13 comes into contact with the step portion 11C of the meshing portion 11A of the right screw nut 11, and the washer 13 is brought into contact with the bolt shaft portion 10A. On the other hand, since the rotation is prevented, the bolt 10 and the nut 11 cannot be rotated in the loosening direction.

  Moreover, the bolt male screw 10C is composed of a right screw 10C-1 and a left screw 10C-2, and the right screw nut 11 and the left screw nut 12 are screwed into the bolt male screw 10C in a double nut shape. Even if the nut is rotated in the loosening direction, the left-hand screw nut 12 cannot be rotated in the loosening direction, and the nut 11 cannot be rotated in the loosening direction.

  In addition, since the outer surface of the fitting protrusion 11D of the nut 11 is strongly pressed against the inner surface of the fitting recess 12D of the nut 12, the left screw nut 12 reliably prevents the right screw 11 from rotating in the loosening direction. To do.

  As a result, the fastening of the bolt 10 and the nuts 11 and 12 can be reliably prevented from loosening, and the fastening reliability can be greatly improved.

10 bolt 10A shaft portion 10B locking groove 10C male screw 10C-1 right screw 10C-2 left screw 11 right screw nut 11A engaging portion 11B inclined surface 11C stepped portion 11D fitting protrusion 12 left screw nut 12B fitting recess 13 washer 13B Locking piece

Claims (3)

In the bolt and nut fastening structure in which the bolt shaft portion is inserted into the insertion hole of the member to be joined, the nut is screwed into the bolt shaft portion, and the washer is interposed between the nut and the member to be joined.
A male screw (10C) is formed on the surface of the bolt shaft (10A), and the male screw (10C) is alternately arranged at positions opposite to each other with respect to a straight line extending parallel to the bolt axis on the surface of the bolt shaft (10A). The right screw half (10C-1) and the left screw half (10C-2) are arranged, and the right screw half (10C-1) and the left screw half (10C-2) have a metal flow. It is formed by rolling into a triangular screw shape so as to be continuous, and a right screw nut (11) and a left screw nut (12) are screwed into a double nut shape to the bolt male screw (10C) to prevent loosening. Bolt and nut loosening prevention structure characterized by this. Of the right screw nut (11) and the left screw nut (12) of the bolt male screw (10C), the screw surface of the washer side nut (11) contacting the washer (13) surface has a screwing direction of the bolt (10). A plurality of meshing portions (11A) having an inclined surface (11B) that allows rotation in the direction of rotation and a rotation blocking portion (11C) that prevents rotation of the bolt (10) in the screwing direction are the washer-side nut (11) seating surface. Are arranged side by side in the circumferential direction, and an elastically deformable locking piece (13B) is provided on the surface of the washer (13). The locking piece (13B) is screwed by a bolt. For rotation in the direction, it is guided by the inclined surface (11B) of the nut engagement portion (11A) and elastically deformed to overcome the rotation prevention portion (11C), and for rotation in the screw retraction direction, the nut engagement Part (11A) rotation prevention part ( 1C) and one abutting,
The bolt shaft portion (10A) is formed with a locking groove (10B) extending in the axial direction, and is fitted into the locking groove (10B) at the inner edge of the bolt shaft portion insertion hole of the washer (13). The bolt / nut loosening prevention structure according to claim 1, wherein a locking projection (13C) is formed to stop the washer (13) from rotating relative to the bolt shaft (10A).   Of the right screw nut (11) and the left screw nut (12), the nut (11) on the washer side has a fitting protrusion (11D) on the opposite side of the washer, and the other nut (12) has The bolt / nut loosening prevention structure according to claim 1 or 2, wherein a fitting recess (12D) into which the fitting protrusion (11D) is fitted is formed on the washer side.

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