JP2015017657A - Bolt-nut locking structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bolt-nut locking structure capable of surely performing locking without increasing the number of components and increasing manufacturing costs.SOLUTION: In a bolt-nut fastening structure in which a bolt shaft portion is inserted into an insertion hole of a joined member, a nut is screwed on the bolt shaft portion, and the nut and the joined member are fastened through a washer therebetween, a bearing surface of the nut 11 and a surface of a washer 12 are provided with a plurality of engagement portions 11A, 12A respectively having inclined planes 11B, 12B for permitting rotation in the screwing direction, of the bolt 10, and rotation inhibiting portions 11C, 12C for inhibiting rotation in the screwing direction of the bolt in a state of being arranged in the circumferential directions of each of the nut bearing surface and the washer surface. On the other hand, a locking recessed groove 10C is formed in a state of being axially extended on the bolt shaft portion, and a locking projection 12D to be fitted to the locking recessed groove to lock the washer to the bolt shaft portion, is formed on an inner edge of the bolt shaft portion insertion hole of the washer.

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, each of the seat surface of the nut and the surface of the washer is provided with an inclined surface that allows rotation of the bolt in the screwing direction and rotation of the bolt in the screwing direction. A plurality of meshing portions each having a rotation preventing portion for blocking are formed side by side in the circumferential direction of each of the nut seat surface and the washer surface, while a locking groove is formed in the bolt shaft portion so as to extend in the axial direction. The inner edge of the bolt shaft portion insertion hole of the washer is formed with a locking projection that fits into the locking groove and prevents the washer from rotating relative to the bolt shaft portion.

  One of the features of the present invention is that the rotation of the bolt in the screwing direction is allowed by the meshing portion of the washer surface and the meshing portion of the nut seating surface, but the rotation of the bolt is prevented and the bolt shaft portion is locked. This is in that the washer is prevented from rotating with respect to the bolt shaft portion by the concave groove and the locking projection of the washer.

  As a result, the bolt or nut can be smoothly rotated by the meshing part of the nut slightly over the inclined surface of the meshing part of the washer in the screwing direction of the bolt. The rotation preventing portions of the meshing portions cannot be rotated in contact with each other, and the bolts and nuts 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.

  The shape of the washer is not particularly limited, but if the washer is formed in a dish-like shape that is curved downward in an arc shape in cross section and an engagement portion is formed on its lower surface, the elastic restoring force of the washer after the bolt and nut are fastened Therefore, the nut is urged in the direction away from the member to be joined, so that there is little rattling of the female screw and the male screw.

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. It is a bottom 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 4 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 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 washer 12 is formed in the shape of a dish curved downward in a circular arc shape using a metal plate, and a plurality of meshing portions 12A are formed on the lower surface (front surface) of the washer 12 in a circumferential direction. The meshing portion 12A includes an inclined surface 12B that allows rotation of the bolt 10 in the screwing direction and a step portion (rotation blocking portion) 12C that prevents rotation of the bolt 10 in the screwing direction.

  On the other hand, a plurality of meshing portions 11A are formed on the seat surface of the nut 11 side by side in the circumferential direction, and each of the plurality of meshing portions 11A allows the rotation of the bolt 10 in the screwing direction and the screwed surface of the bolt 10. It is composed of a step portion (rotation prevention portion) 11 </ b> C that prevents rotation in the backward direction, and the meshing portion 11 </ b> A of the nut 11 is linked to the meshing portion 12 </ b> A of the washer 12.

  A pair of locking grooves 10C are formed in the bolt shaft portion 10B so as to extend in the axial direction with an angular interval of 180 ° from each other. A pair of locking protrusions 12D 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 locking projection 12D is fitted into the locking groove 11C so that the washer 12 is prevented from rotating with respect to the bolt shaft portion 10B.

  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 projection 12D 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 nut 11 comes into contact with the washer 12, the washer 12 is sandwiched between the seat surface of the nut 11 and the member 15 to be joined, and is gradually deformed from a convex arc shape in cross section to a flat plate shape, and the meshing portion 11A of the nut 11 and the washer The twelve meshing portions 12A come into contact with each other.

  Then, the engaging portion 11A of the nut 11 and the engaging portion 12A of the washer 12 have the inclined surfaces 11B and 12B that allow the bolt 10 to be screwed in sliding contact with each other so as to get over the step portions 11C and 12C. The nut 11 is screwed and tightened, and the lower surface of the washer 12 and the seat surface of the nut 11 are in close contact with each other.

  In this state, when the bolt 10 or the nut 11 tries to rotate in the loosening direction, the step portion 11C of the engaging portion 11A of the nut 11 and the step portion 12C of the engaging portion 12A of the washer 12 come into contact with each other, and the washer 12 is Since the bolt 10 and the nut 11 cannot be rotated in the direction in which the fastening is loosened, the bolt 10 and the nut 11 are reliably prevented from loosening.

  As described above, according to the loosening prevention structure of this example, the number of parts does not increase, and the engaging portions 11A and 12A may be processed on the seat surface of the nut 11 and the surface of the washer 12, thereby increasing the manufacturing cost. It is possible to reliably prevent the bolt 10 and the nut 11 from loosening without being invited.

DESCRIPTION OF SYMBOLS 10 Bolt 10A Head part 10B Shaft part 11 Nut 11A, 12A Engagement part 11B, 12B Inclined surface 11C, 12C Step part 12 Washer 14, 15 Joined member

Claims (2)

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.
Each of the bearing surface of the nut (11) and the surface of the washer (12) has an inclined surface (11B, 12B) that allows the bolt (10) to rotate in the screwing direction and a screwing direction of the bolt (10). While a plurality of meshing portions (11A, 12A) having rotation blocking portions (11C, 12C) for blocking rotation are formed side by side in the circumferential direction of each of the nut (11) seat surface and the washer (12) surface,
The bolt shaft portion (10B) is formed with a locking groove (10C) extending in the axial direction, and is fitted into the locking groove (10C) at the inner edge of the bolt shaft insertion hole of the washer (12). A locking projection (12D) for locking the washer (12) with respect to the bolt shaft (10B) is formed.   The bolt / nut loosening prevention structure according to claim 1, wherein the washer (12) is formed in a dish-like shape curved downward in an arc shape in cross section, and the engagement portion (12A) is formed on the lower surface thereof.

Images