JP6231796B2 - Bolt / nut locking structure - Google Patents

Description

  The present invention relates to a structure for preventing bolts and nuts from loosening, and more particularly, to a structure in which bolts and nuts screwed together are not easily loosened.

  For example, when fastening a member, a method is generally used in which an insertion hole is formed in the member, a bolt is inserted into the insertion hole, a female screw of a nut is screwed into a male screw of the bolt, and a bolt / nut is tightened. .

  Since fastening with this bolt / nut may cause loosening due to vibration, thermal expansion, secular change, and the like, various loosening prevention methods have been proposed. For example, a loosening prevention plate is fixed to the periphery of the screw hole on the top surface or seating surface of the nut, and the loosening prevention plate is elastically deformed and pressed against the thread flank of the bolt, thereby providing a rotational resistance to the nut. A stop structure is known (Patent Document 1).

  In addition, an arc-shaped lock portion whose tip side is deflected toward the center of the nut is integrally formed on the top surface of the nut, while a recess is formed in the male thread of the bolt, and the tip of the lock portion is inserted into the recess. This prevents the nut from rotating in the loosening direction, while the locking part is elastically deformed and the tip of the locking part is pulled out of the recess to allow the nut to rotate in the tightening direction. It has been proposed (Patent Document 2).

  In addition, each of the bearing surface of the bolt and nut and the surface of the washer with which the seat surface comes into contact, an inclined surface that allows the bolt to rotate in the screwing direction, and a step portion that prevents the bolt from rotating in the screwing direction. There has been proposed a technique in which a plurality of meshing portions having a shape are formed side by side in the circumferential direction to prevent bolts from loosening (Patent Document 3).

  The slack prevention technique described in Patent Document 3 has the advantage that the number of parts is small and the cost of manufacturing is less likely to occur than the techniques of Patent Documents 1 and 2.

Japanese Patent Laid-Open No. 2001-124043 Japanese Patent Laid-Open No. 2002-242921 Japanese Utility Model Publication No. 52-13356

  However, in the loosening prevention structure described in Patent Document 3, the loosening prevention performance depends on the friction between the washer and the member to be joined, and if the washer rotates with respect to the member to be joined, it is easy to fasten the bolt and nut. It can be loosened.

  SUMMARY OF THE INVENTION In view of such problems, the present invention provides a bolt / nut loosening prevention structure that can reliably prevent loosening without increasing the number of parts and without increasing the manufacturing cost. Is an issue.

  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 recess is formed in a region including a screw hole on the seat surface of the nut, and the surface of the recess is rotated in the screwing direction of the bolt. A plurality of meshing portions having an inclined surface to be allowed and a rotation preventing portion for preventing rotation of the bolt in a screwing direction are formed side by side in the circumferential direction of the nut seat surface, and a fitting recess is formed on the surface of the washer The fitting recess is fitted with an elastically deformable locking piece portion having a side hook shape, and the locking piece portion is configured to rotate the nut in the screwing direction. By being elastically deformed guided by the inclined surface of the meshing part The bolt is allowed to rotate in the screwing direction over the rotation blocking part, and the bolt is screwed in contact with the rotation blocking part of the meshing part of the nut against the rotation of the bolt in the screwing direction. On the other hand, the bolt shaft part is formed with a locking groove extending in the axial direction, and the bolt shaft part insertion hole of the washer is fitted into the locking groove to prevent the rotation in the direction. A locking projection for stopping the washer from rotating with respect to the bolt shaft portion is formed.

  One of the features of the present invention is that the locking piece portion of the washer surface and the engaging portion of the recess of the nut seat surface allow rotation of the bolt in the screwing direction but prevent rotation in the bolt screwing direction, This is in that the washer is prevented from rotating with respect to the bolt shaft portion by the locking concave groove of the bolt shaft portion and the locking projection of the washer.

  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.

  Moreover, since the washer is prevented from rotating with respect to the bolt shaft part by the locking groove of the bolt shaft part and the locking projection of the washer, the locking performance depends on the friction between the washer and the member to be joined. As a result, 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.

  Since the locking piece is fitted into the fitting recess of the washer, the locking piece interferes with the top of the inclined surface of the meshing portion of the nut when the bolt rotates in the screwing direction, and an excessive load is applied. However, in the present invention, a recess is formed on the nut seat surface, and a meshing portion is formed on the surface of the recess. There is no risk of overload acting.

It is sectional drawing which shows preferable embodiment of the bolt / nut loosening prevention structure of this invention. It is a figure which shows the meshing part of the washer surface (A) and nut seat surface (B) in the said embodiment. It is a side view which shows the relationship between a washer and a nut in the said embodiment.

  Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 to 3 show a preferred embodiment of a bolt / nut locking structure according to the present invention. In the figure, the members to be joined 14 and 15 are fastened and joined by bolts 10, nuts 11 and washers 12 and 13.

  The bolt 10 includes a head portion 10A and a shaft portion 10B, and a male screw is formed on the shaft portion 10B so that a nut 11 is screwed.

  The seat surface of the nut 11 is formed with a recess 11D in a region including a screw hole, and a plurality of meshing portions 11A are formed in the circumferential direction on the surface of the recess 11D. An inclined surface 11B that allows rotation in the screwing direction and a step portion (rotation blocking portion) 11C that prevents rotation of the bolt 10 in the screwing direction.

  On the other hand, the washer 12 is formed into a flat disk shape using a metal plate, and a fitting recess 12B is formed on the surface of the washer 12, and the fitting recess 12D is an elastically deformable engagement having a side hook shape. The engaging portion of the nut 11 is fitted by the engaging piece 12A being fitted and elastically deformed by being guided by the inclined surface 11B of the engaging portion 11A of the nut 11 with respect to the rotation of the bolt 10 in the screwing direction. The locking piece 12A is brought into contact with the stepped portion 11C of the meshing portion 11A of the nut 11 with respect to the rotation of the bolt 10 in the screwing direction over the stepped portion 11C of 11A.

  In addition, a pair of locking grooves 10C are formed in the bolt shaft portion 10B so as to extend in the axial direction at an angular interval of 180 °, and a pair of locking protrusions 12C are formed on the inner edge of the bolt insertion hole of the washer 12. Are formed at an angular interval of 180 ° from each other, and the washer 12 is prevented from rotating with respect to the bolt shaft portion 10B by fitting the locking projection 12C into the locking groove 11C.

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

  When the preparation is completed in this manner, the nut 11 is fixed with an appropriate tool, and the bolt 10 is rotated and screwed. When the periphery of the seat surface of the nut 11 comes into contact with the washer 12, the locking piece portion 12A of the washer 12 comes into contact with the meshing portion 11A of the nut 11.

  Then, the locking piece portion 12A of the washer 12 is slidably brought into contact with the inclined surface 12B of the engaging portion 11A of the nut 11 and is elastically deformed to overcome the step portion 11C of the engaging portion 11A. And the nut 11 is tightened, and the lower surface of the washer 12 and the periphery of the seat surface of the nut 11 are in close contact with each other.

  When the bolt 10 or the nut 11 tries to rotate in the loosening direction in this state, the locking piece portion 12A of the washer 12 comes into contact with the step portion 11C of the engaging portion 11A of the nut 11, and the washer 12 is the bolt shaft portion 10B. Therefore, the bolt 10 and the nut 11 cannot be rotated in the direction in which the fastening is loosened, and are securely loosened.

  As described above, according to the loosening prevention structure of this example, the number of parts does not increase, and the engagement portion 11A may be processed on the seat surface of the nut 11 and the locking piece portion 12A on the surface of the washer 12. It is possible to reliably prevent loosening of the bolt 10 and the nut 11 without causing an increase in manufacturing cost.

DESCRIPTION OF SYMBOLS 10 Bolt 10A Head part 10B Shaft part 10C Locking groove 11 Nut 11A Engagement part 11B Inclined surface 11C Step part 11D Recess 12 Washer 12A Locking piece part 12C Locking protrusion 14, 15

Claims (1)

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.
The nut (11) has a recess (11D) in a region including the screw holes in the seat surface, leaving a portion of the nut (11) washer seating surface rim (12) is in contact with the surface of the recess (11D) A plurality of meshing portions (11A) having an inclined surface (11B) that allows rotation of the bolt (10) in the screwing direction and a rotation blocking portion (11C) that prevents rotation of the bolt (10) in the screwing direction. Are arranged in parallel in the circumferential direction of the seat surface of the nut (11), and the washer (12) has a fitting recess (12B) on the surface facing the nut seat surface, and the fitting recess (12B) Is fitted with an elastically deformable leaf spring locking piece (12A) having a planar rectangular shape and a side hook shape,
The locking piece (12A) is elastically deformed by being guided by the inclined surface (11B) of the meshing portion (11A) of the nut (11) with respect to the rotation of the bolt (10) in the screwing direction. To allow the bolt (10) to rotate in the screwing direction over the rotation preventing part (11C), and to engage the nut (11) with respect to rotation of the bolt (10) in the screwing direction. (11A) is in contact with the rotation preventing portion (11C) to prevent the bolt (10) from rotating in the screwing direction, and the recess (12B) is the periphery of the nut (11) seat surface. When the portion and the washer (12) start to come into contact with each other, the upper side edge of the side face of the locking piece (12A) can come into contact with the inclined surface (11B) of the meshing part (11A) of the nut (11). Has a depth,
Extending locking groove (10C) is in the axial direction to the bolt shaft portion (10B), said washer (12) has a locking projection (12D) on the inner edge of the bolt shaft portion insertion hole, said locking projection (12D) is locking bolts and nuts, characterized in that is adapted to detent the washers (12) fitted to the locking groove (10C) bolt shank with respect to (10B) Construction.

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