JP6215601B2 - 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, the washer has a dish-like shape curved downward in a circular arc shape in cross section, and the bolt screwing direction is provided on each of the nut seat surface and the lower surface of the washer. A plurality of meshing portions each having an inclined surface that allows rotation to and a rotation preventing portion that prevents rotation of the bolt in a screwing direction are formed side by side in the circumferential direction of each of the nut seat surface and the washer bottom surface, 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 to prevent the washer from rotating with respect to the bolt shaft portion. The above-mentioned nut seat surface is formed with a locking projection A step portion is formed on the entire periphery of the screw hole, and a guide protrusion is formed on the periphery of the bolt shaft insertion hole on the lower surface of the washer so as to guide the rotation of the nut with respect to the washer. It is characterized by that.

  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 smoothly rotate in the screwing direction of the bolt with the meshing portion of the nut slightly passing over the inclined surface of the meshing portion of the washer. 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.

  Further, the second feature of the present invention is that the washer is formed in a dish-like shape that is curved downward in a circular arc shape in cross section, a step is formed on the entire periphery of the screw hole of the nut seat surface, and the bolt shaft portion is inserted into the lower surface of the washer. A guide protrusion is formed on the periphery of the hole, and the guide protrusion is loosely fitted to the step portion to guide the rotation of the nut relative to the washer.

  As a result, even if the washer has a dish-like shape curved downward in the shape of a circular arc in cross section, the nut is stably rotated with respect to the washer. The inclined surface can be rotated lightly and stably and smoothly.

  When the washer is formed in a dish-like shape curved downward in an arc shape in cross section, and the engagement portion is formed on the lower surface thereof, the nut is separated from the member to be joined by the elastic restoring force of the washer after the bolt and nut are fastened. Therefore, there is little rattling of the internal thread and the external thread.

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 of the washer 12 in the circumferential direction, and the plurality of meshing portions 12A. Is composed of an inclined surface 12B that allows rotation of the bolt 10 in the screwing direction and a step portion (rotation blocking portion) 12C that blocks 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.

  Further, a step portion 11D is formed on the seat surface of the nut 11 over the entire circumference of the screw hole, and guide protrusions 12E are formed on the lower surface of the washer 12 on the periphery of the bolt insertion hole with an angular interval of 180 ° from each other. The guide protrusion 12E is loosely fitted to the step portion 11D of the seat surface of the nut 11 so as to guide the rotation of the nut 11 with respect to the washer 12.

  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 guide protrusion 12E of the washer 12 is loosely fitted to the step portion 11D of the seat surface of the nut 11, and the washer 12 is sandwiched between the seat surface of the nut 11 and the member 15 to be joined. As a result, the cross section is gradually deformed from a convex arc shape into a flat plate shape, and comes into contact with each other from the meshing portion 11A of the nut 11 and the meshing portion 12A of the washer 12.

  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 11D Nut part 12 Washer 12E Washer guide protrusion 14,15 Member to be joined

Claims (1)

Insert the bolt shaft part into the insertion hole of the member to be joined, screw the nut into the bolt shaft part, and tighten the bolt head and nut with a washer between the nut and the member to be joined. In the bolt and nut fastening structure
When the front end side of the bolt shaft portion (10B) is on the lower side and the surface on the front end side is the lower surface on the basis of the bolt head (10A), the washer (12) is a dish-like shape curved downward in an arcuate cross section. The inclined surface (11B, 12B) and the screw of the bolt (10) that allow the bolt (10) to rotate in the screwing direction are respectively formed on the seat surface of the nut (11) and the lower surface of the washer (12). A plurality of meshing portions (11A, 12A) having rotation preventing portions (11C, 12C) for preventing rotation in the backward direction are arranged in parallel in the circumferential direction of each of the nut (11) seat surface and the washer (12) bottom surface. while there,

The bolt shaft portion (10B) has a locking groove (10C) extending in the axial direction, and the inner edge of the bolt shaft portion insertion hole of the washer (12) has a locking projection (12D). The stop projection (12D) is inserted into the locking groove (10C) to stop the washer (12) from rotating with respect to the bolt shaft (10B) .
Seat surface of the nut (11) has a stepped portion (11D) on the entire circumference edge of the screw holes of the seat surface, the washer (12) guide projections on the periphery of the bolt shaft portion insertion hole of the lower surface (12E ) has a bolt-which the guide projection (12E) is equal to or adapted to be loosely fitted in the stepped portion (10D) for guiding the rotation relative washers (12) of the nut (11) Nut locking structure.

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