JP7448145B2 - Screw fastening structure - Google Patents

Description

The present invention relates to a screw fastening structure using a male threaded body and a female threaded body.

Conventionally, fastening screws have two types: a male threaded body with a spiral groove formed on the outer circumferential surface of a round bar, and a spiral groove formed on the inner circumferential surface of a cylindrical member. When in use, the male threaded body is inserted into a screw hole drilled through the material to be fastened, and then the female threaded body is screwed onto this male threaded body, so that the male threaded body is inserted in advance. The fastening is achieved by tightening the fastened members with the female screw body. One type of fastening screw that has been devised to be easily usable is a so-called bolt with a hexagonal columnar head formed at one end of a male threaded body, and an outer circumferential surface that is screwed into the bolt. There is one that consists of a combination with a so-called nut formed in a hexagonal column shape.
Most conventional screw applications, such as fastening bolts and nuts, use right-handed threads, while left-handed threads are used for turnbuckles, etc., where female threads are coaxially formed at both ends with different rotational directions. For special purposes only.
Further, there are applications in which a screw consisting of a bolt/nut combination is required to prevent the nut screwed onto the bolt from loosening. As a screw devised to meet such uses, there is a screw known as a locking nut. This is constructed so that the nut, which is screwed onto the bolt, becomes difficult to loosen by applying appropriate measures to the nut.
Conventional locking nuts can be roughly divided into so-called single-nut type nuts that provide a locking effect with one nut, and so-called double-nut type nuts that provide a locking effect with a combination of two nuts. There is also a nut type.
As disclosed in Patent Document 1, a typical conventional single-nut type locking nut is constructed by incorporating a mechanism that acts like a washer into the nut, and when screwed onto a bolt, A washer-like plate piece fixed to one end of the nut exerts an urging force between the helical groove of the bolt and the nut, thereby suppressing the loosening of the nut.
As disclosed in Patent Document 2, a typical conventional double-nut locking nut includes a first nut having a reduced diameter end configured to be able to reduce the diameter, and a reduced diameter end of this nut. a second nut that is screwed onto the outer periphery of the bolt to reduce the diameter of the reduced diameter end; The second nut is screwed together, and the diameter-reduced end of the first nut is reduced in diameter so that its inner peripheral surface is firmly pressed into contact with the helical groove of the bolt, thereby suppressing loosening of the nut. It is something.

Patent No. 3946752 Registered utility model No. 3018706

In addition, in the case of a conventional locking nut, in the case of a single nut system, although it is possible to obtain some loosening suppressing effect with one nut, the washer is simply The plate piece creates a biasing force to tighten the engagement between the bolt and nut, and does not essentially prevent the nut from loosening.In the case of the double nut method, the first The reduced diameter end of the nut is reduced in diameter by a second nut, and the result is similar to the single nut method, with the inner circumferential surface having unevenness, etc. on the reduced diameter end within one spiral groove on the outer circumferential surface of the bolt. The bolt and nut are brought into pressure contact, the engagement between the bolt and nut is tightened, and loosening is suppressed by the frictional force between the outer circumferential surface of the bolt and the inner circumferential surface of the nut. There was a problem with putting it away.

The present invention has been achieved through intensive research by the inventors in view of the above problems, and an object of the present invention is to provide a means for preventing loosening of a male threaded body and a female threaded body with a simple structure.

The screw fastening structure of the present invention is a fastening structure for a fastening body having a male threaded body and a female threaded body, and is characterized by having a relative rotation prevention member surrounding the male threaded body and inserted into the female threaded body.

In relation to the screw fastening structure, the relative rotation prevention member has an engagement surface that engages with the engagement hole of the female threaded body on its outer periphery, and a non-circular shape that substantially corresponds to the outer shape of the male threaded body when viewed in the axial direction. an insertion hole, the male threaded body can be fitted into the insertion hole in a state in which relative rotation is not possible, and the engagement surface engages with the inner periphery of the engagement hole.

In relation to the screw fastening structure, the engagement surface is characterized in that unevenness is arranged in the circumferential direction.

In relation to the screw fastening structure, the engagement surface has a tapered shape that decreases in diameter toward one end facing the female threaded body, and is configured to come into close contact with the tapered inner circumferential surface of the engagement hole. Features.

In relation to the screw fastening structure, the engagement surface has a partially interrupted part in the circumferential direction and is configured to be elastically deformable in the radial direction, and the engagement surface is configured to be elastically deformable in the radial direction by the inner peripheral surface of the engagement hole. It is characterized in that it is pressed in the direction and comes into close contact with the circumferential surface of the surrounding male threaded body.

The screw fastening structure is characterized in that a relative displacement prevention member is provided which is screwed onto the male threaded body and prevents relative displacement in the axial direction between the female threaded body and the male threaded body.

In relation to the screw fastening structure, an engagement mechanism is provided between the relative rotation prevention member and the relative displacement prevention member.

In relation to the screw fastening structure, the engagement mechanism includes a plurality of protrusions and recesses arranged in the circumferential direction on the end face of the relative rotation prevention member, and a plurality of protrusions and depressions arranged in the circumferential direction on the end face of the relative displacement prevention member. It is characterized by being made up of unevenness.

In relation to the screw fastening structure, the end surface of the relative rotation prevention member is a substantially annular first tapered surface whose diameter decreases or expands toward the outside in the axial direction, and the end surface of the relative displacement prevention member is axially It is a substantially annular second tapered surface that expands or contracts in diameter toward the outside in the direction, and is characterized in that the first tapered surface and the second tapered surface contact and engage in the circumferential direction.

In relation to the screw fastening structure, the male screw body has a first helical thread set at an appropriate lead angle and/or lead direction, and a lead angle and/or lead direction set different from the first helical thread. the female threaded body has a first spiral groove that can be screwed into the first spiral groove, and the relative displacement prevention member can be screwed into the second spiral groove. It is characterized by having a second spiral groove.

According to the present invention, a male threaded body and a female threaded body can be surely prevented from loosening with a simple structure.

FIG. 2 is a front partial sectional view showing the screw fastening structure according to the first embodiment. FIG. 2 is a perspective view showing a male threaded body of the screw fastening structure according to the first embodiment. FIG. 3 is a diagram showing a female threaded body of the screw fastening structure according to the first embodiment. It is a figure showing the relative rotation prevention member of the screw fastening structure concerning a first embodiment. It is a figure showing the relative displacement prevention member of the screw fastening structure concerning a first embodiment. It is a top view which shows the uneven|corrugated part of a relative displacement prevention member. It is a figure which shows the fastening procedure by the screw fastening structure based on 1st embodiment. They are (a) a front view and a bottom view of a male threaded part used in a screw fastening structure, and (b) a plan view of a relative rotation prevention member. FIG. 7 is a diagram showing a male threaded body of a screw fastening structure according to a second embodiment. It is a top view which shows the male thread part based on 2nd embodiment. FIG. 7 is a side view showing a male threaded portion according to a second embodiment. It is a figure showing a relative rotation prevention member. It is a sectional view showing a relative displacement prevention member of a second embodiment. It is a figure which shows the fastening procedure by the screw fastening structure based on 2nd embodiment.

Embodiments of the screw fastening structure of the present invention will be described below with reference to the drawings. FIG. 1 is a side partial sectional view showing a screw fastening structure 1 according to a first embodiment. The screw fastening structure 1 includes a male screw body 10, a female screw body 20, a relative rotation prevention member 30, and a relative displacement prevention member 40, and fastens the fastened members 100 and 110.

The male threaded body 10 includes a head 12 and a shaft portion 14, as shown in FIG. The head 12 expands radially outward compared to the shaft portion 14 and has a hexagonal outer circumferential surface. Here, the shaft portion 14 includes a male thread portion 15 in which a right-handed male thread spiral groove is formed from the base side toward the distal end, but it may of course be left-handed threaded. Note that the shaft portion 14 may have a cylindrical portion in the head 12 rather than the male screw portion 15, but of course the cylindrical portion is not an essential configuration.

FIG. 3 shows the female threaded body 20, with (a) being a perspective view and (b) being a sectional view. The female threaded body 20 is a so-called nut, has a cylindrical shape, and has a female threaded portion 22 as a right-handed thread on its inner circumferential surface to be screwed into the male threaded body 15 . Furthermore, an engagement hole 24 is formed in the female threaded body 20 at one end in the axial direction that faces a relative rotation prevention member 30, which will be described later. The inner circumferential surface defining the engagement hole 24 has a tapered shape that widens toward the opening, that is, a concave tapered shape that slopes in the radial direction.

Further, on the inner circumferential surface of the engagement hole 24, a female thread side unevenness 26 is formed by a plurality of flat knurl-like unevenness along the axial direction. The engagement hole 24 is set to have a hole shape larger in diameter than the root diameter of the female threaded portion 22 so that the relative rotation prevention member 30 can be interposed between the engagement hole 24 and the male threaded body 10. In addition, the structure of the inner circumferential surface of the engagement hole 24 here is a flat knurling-like structure along the axial direction, but it does not necessarily have to be in this form. There is no particular limitation, as long as relative rotation is prevented when the relative rotation prevention member 30 is fitted with the main body portion 32.

FIG. 4 shows the relative rotation prevention member 30, in which (a) is a perspective view, (b) is a side view, and (c) is a plan view. The relative rotation prevention member 30 has a main body portion 32 having a substantially ring shape and a flange portion 34 . Note that although the flange portion 34 is provided here, this is not necessarily necessary. Further, the relative rotation preventing member 30 has an inner circumferential surface 36 that surrounds and comes into close contact with the male threaded body 10.

The main body portion 32 has an external shape that can be engaged with the engagement hole 24 . That is, the outer circumferential surface of the main body portion 32 has a tapered shape that corresponds to the inner circumferential surface of the engagement hole 24 and gradually decreases in diameter from the flange portion 34 side toward the distal end side. On the outer circumferential surface of the main body portion 32, member-side unevenness 38 is formed by a plurality of flat knurling-like unevenness along the axial direction.

Furthermore, a plurality of slits 37 extending in the axial direction are formed on the outer circumferential surface of the main body portion 32 at predetermined intervals in the circumferential direction. Therefore, the main body portion 32 can be elastically deformed in the radial direction so that the slit 37 narrows or widens.

Note that the outer circumferential surface of the main body portion 32 and/or the concave inner circumferential surface of the engagement hole 24 is not limited to a tapered shape, but can be set to a straight shape, a curved shape, a curved shape, etc., and preferably an engaged shape. The shape corresponds to the matching hole 24 or the main body portion 32. Further, the member-side unevenness 38 is not limited to a flat knurled shape along the axial direction, but may be engaged with a rotation prevention means provided in the engagement hole 24 to prevent relative rotation. If it is possible, it can be set appropriately.

The flange portion 34 is set to have a larger outer diameter than the main body portion 32, and has a concave tapered end face in the axial direction. That is, it forms an inner circumferential tapered surface whose diameter increases outward in the axial direction. Further, the flange portion 34 has a plurality of irregularities 34a along the circumferential direction on the end surface. The unevenness 34a preferably has a sawtooth shape, and the direction in which the unevenness 34a extends, that is, the direction in which the ridgeline extends, is preferably set along the radial direction of the relative rotation prevention member 30. As a result, the unevenness 34a on the end surface of the flange portion 34 extends radially from the axis. Of course, if the flange portion 34 is not provided, the unevenness 34a may be provided on the end surface of the main body portion 32.

The inner circumferential surface 36 has a non-perfect circular shape when viewed in the axial direction, and here it has a substantially elliptical shape, for example, when the axis is aligned with the male threaded body 10 so that the short diameter portion can press the male threaded body 10. A portion thereof is configured to interfere with the outer circumferential surface of the male threaded body 10.

FIG. 5 shows the relative displacement prevention member 40, in which (a) is a perspective view and (b) is a side view. The relative displacement prevention member 40 has a substantially hexagonal outer shape, a cylindrical shape through which a hole 40a that can surround the male threaded body 10 passes through, and a right-handed helical thread for the male threaded portion 15 to be screwed into the inner peripheral surface. It has a section 42. Here, the outer shape of the relative displacement prevention member 40 is approximately hexagonal, but the outer shape is not limited to this and may be any suitable shape. In particular, if the shape is an irregular shape such as a rectangular shape or an elliptical shape, the fastening performance can be improved.

Further, one end surface in the axial direction of the relative displacement prevention member 40 is configured to have a convex tapered shape (an outer peripheral tapered surface whose diameter decreases toward the outside in the axial direction) that can come into surface contact with the end surface of the flange portion 34. However, it is preferable to prevent relative rotation between the two in view of fitability with the end surface of the relative rotation prevention member 30 provided with the unevenness 34a.

Moreover, a plurality of uneven portions 44 (see FIG. 6) are formed along the circumferential direction on one end surface of the relative displacement prevention member 40. The uneven portion 44 is configured to undulate in an appropriate shape that can engage with the unevenness 34a of the flange portion 34, but here it is set to have a saw blade shape and extend radially from the axis. .

Therefore, at the location where the relative rotation prevention member 30 and the relative displacement prevention member 40 abut, the unevenness 34a and the unevenness portion 44 function as a relative rotation prevention mechanism that prevents the relative rotation of both members 30, 40. That is, the saw blade orientation of the unevenness 34 and the uneven portion 44 is set such that the relative displacement prevention member 40 allows relative rotation in the tightening direction and restricts relative rotation in the loosening direction.

Next, the operation of this screw fastening structure 1 will be explained. As shown in FIG. 7(a), the fastened members 100, 110 are inserted into the male threaded body 10, and the female threaded body 20 is tightened. Next, as shown in FIG. 7(b), the relative rotation prevention member 30 is inserted into the male threaded body 10. At this time, the relative rotation prevention member 30 is moved in the axial direction to a position where the main body 32 is inserted into the engagement hole 24, with the main body 32 facing the female threaded body 20, as shown in FIG. 7(c).

The relative rotation prevention member 30 engages with each of the male threaded body 10 and the female threaded body 20 in the circumferential direction. That is, the female thread side unevenness 26 of the engagement hole 24 of the female threaded body 20 and the member side unevenness 38 on the outer peripheral surface of the relative rotation prevention member 30 engage in the circumferential direction.

Moreover, the inner circumferential surface 36 of the main body portion 32 is in close contact with the male threaded body 10 . That is, the inner circumferential surface 36 of the main body part 32 biases the male threaded body 10 in the radial direction, and the body part 32 is fitted into the engagement hole 24, thereby restricting deformation in the radial direction. As a result, the main body portion 32 firmly presses the shaft portion 14 inward in the radial direction and comes into close contact with the shaft portion 14, and relative displacement of the relative rotation prevention member 30 in the axial direction and the circumferential direction with respect to the male threaded body 10 is restricted.

Next, as shown in FIG. 7(d), the relative displacement prevention member 40 is screwed onto the male threaded body 10 and tightened. At this time, the uneven portion 44 engages with the unevenness 34a of the relative rotation prevention member 30 in the circumferential direction. The engagement structure formed by both members 30 and 40 allows relative rotation of the relative displacement prevention member 40 in the tightening direction (direction of spiraling toward the relative rotation prevention member 30 side), and restricts relative rotation in the loosening direction.

As a result, the male threaded body 10, the female threaded body 20, the relative rotation prevention member 30, and the relative displacement prevention member 40 are substantially integrated. That is, the relative rotation prevention member 30 has an inner circumferential surface in close contact with the male threaded body 10 and engages with the male threaded body 10 so that relative rotation with respect to the male threaded body 10 can be restricted. Further, the outer circumferential surface of the relative rotation prevention member 30 engages with the female threaded body 20 in the circumferential direction, so that relative rotation with respect to the female threaded body 20 is restricted. Therefore, the male threaded body 10 and the female threaded body 20 cannot rotate relative to each other through the relative rotation prevention member 30, and the female threaded body 20 has a structure that does not become mechanically loose.

Further, by tightening the relative displacement prevention member 40, the relative rotation prevention member 30 is sandwiched between the female threaded body 20 and the relative displacement prevention member 40, and displacement in the axial direction is restricted. In addition, the relative displacement prevention member 40 engages with the relative rotation prevention member 30 in the circumferential direction to restrict relative rotation in the loosening direction, so that it is almost impossible to separate from the relative rotation prevention member 30. This provides a structure in which the female screw body 20 does not loosen.

As described above, by inserting the relative rotation prevention member into the engagement hole of the female threaded body, it is possible to obtain a screw fastening structure in which the female threaded body does not loosen relative to the male threaded body. In addition, by disposing the relative displacement prevention member at a location facing the female threaded body with the relative rotation prevention member in between, displacement of the relative rotation prevention member in the axial direction is restricted and it is possible to remove it from the engagement hole. can be prevented.
In addition, since the relative rotation prevention member and the relative displacement prevention member are engaged in the circumferential direction, it is possible to prevent the relative displacement prevention member from rotating in the direction of loosening, and the relative rotation prevention member and the relative displacement The prevention member can be substantially integrated.

Further, since the relative rotation prevention member 30 has the slits 37 formed in the main body portion 32, the outer circumferential surface is intermittently divided in the circumferential direction, so that each member is easily elastically deformed and/or plastically deformed. Thereby, the main body portion 32 can be elastically deformed and/or plastically deformed so as to bend inward, and can be brought into closer contact with the male threaded body 10 more firmly. Further, when the main body portion 32 is elastically and/or plastically deformed radially inward, the inner circumferential surface of the main body portion 32 comes into close contact with the outer circumferential surface of the male threaded body 10 and presses it radially inward. As a result, the relative rotation prevention member 30 can be more firmly fixed to the male threaded body 10. Furthermore, although the outer circumferential surface of the main body portion 32 has a tapered shape corresponding to the inner circumferential surface of the engagement hole 24, the outer circumference of the engagement hole 24 can be formed into a tapered shape different from that of the engagement hole 24. The shape may be set so that it is pressed radially inward from the inner peripheral surface. Specifically, the shape has a slightly gentler taper angle than the taper angle of the engagement hole 24, and the outer diameter of the axial tip of the main body portion 32 exceeds the inner diameter of the innermost part of the engagement hole 24. Then, as the main body part 32 enters the engagement hole 24, it is gradually pressed from the inner peripheral surface of the engagement hole 24, so that it is surely elastically deformed inward in the radial direction and firmly attached to the male threaded body 10. It can be brought into close contact with the

In addition, in the embodiment described above, the relative rotation was regulated by the inner circumferential surface of the relative rotation prevention member coming into close contact with the male threaded body 10, but the threads of the male threaded portion 15 are partially omitted. The relative rotation prevention member and the male thread body may be engaged with each other by forming the male thread side engaging portion. Specifically, as shown in FIG. 8, by omitting (or cutting) a part of the circular arc of the circular cross section formed along the top of the thread of the male thread part 15 along its chord, the male thread side connection can be made. A joint 16 is formed (see FIG. 8(a)). When such a male thread side engaging portion 16 is formed, the shape of the male thread portion 15 when viewed in the axial direction becomes a non-perfect circular shape.

Further, as shown in FIG. 8(b), the relative rotation prevention member 30 has an inner peripheral shape that corresponds to the shape of the male threaded portion 15 when viewed in the axial direction, and a part of the inner peripheral surface 36 is formed as an engagement surface. 36a. The position of the engaging surface 36a from the axis is set so that when the relative rotation prevention member 30 is inserted into the male threaded body 10, the engaging surface 36a faces the male thread side engaging portion 16 and interferes with the thread of the male threaded portion 15. be done.

By providing such male thread side engaging portion 16 and engagement surface 36a, relative rotation between male thread body 10 and relative rotation prevention member 30 can be reliably prevented. That is, the relative rotation prevention member 30 can be inserted into the male thread body 10 with the engagement surface 36a facing the male thread side engagement portion 16, and when rotated relative to the male thread body 10, the engagement surface 36a interferes with the thread of the male threaded portion 15, and can reliably prevent relative rotation.

In the above embodiment, the relative displacement prevention member 30 is fitted into the engagement hole 24 of the female threaded body 20 to prevent displacement in the axial direction. 40 is used, but the relative displacement prevention member 40 can also be formed integrally with the end of the engagement hole 24 of the female threaded body 20. In this case, on the end side of the engagement hole 24, in order to maintain the fitted state of the relative rotation prevention member 30 and prevent it from slipping out, a pullout prevention portion protruding inward in the radial direction is provided to prevent the relative rotation prevention member 30 from slipping out. 30 to prevent displacement in the axial direction.

Next, a screw fastening structure in the second embodiment will be explained. The screw fastening structure of the second embodiment is configured such that the male threaded body 50 has a right-handed threaded helical groove structure and a left-handed threaded helical groove structure overlapped in the same area, and the relative displacement prevention member 60 is It has a left-handed spiral thread, which is different from the female threaded body. In the following description, the same reference numerals are used for the same components as those of the screw fastening structure 1 of the first embodiment, and the description thereof will be omitted.

FIG. 9 is a diagram showing a male threaded body of a screw fastening structure according to the second embodiment. The shaft portion 52 of the male threaded body 50 is provided with a male threaded portion 54 . The male threaded portion 54 has two types of male threaded helical grooves, a first male threaded helical groove 54a (see FIG. 11) that is a right-handed thread, and a second male threaded helical groove 54b (see FIG. 11) that is a left-handed thread, overlapping each other in the same area. It is formed by Therefore, the male threaded portion 54 can be screwed into either a right-handed or left-handed female threaded body.

As shown in FIG. 10, the male threaded portion 54 has a thread G that is approximately crescent-shaped and extends circumferentially in a surface direction perpendicular to the axis (screw axis) C. They are provided alternately on one side (right side in the figure) and the other side (left side in the figure) in the diametrical direction. That is, the ridgeline of this thread G extends perpendicularly to the axis, and the height of the thread G changes such that it becomes higher at the center in the circumferential direction and gradually becomes lower at both ends in the circumferential direction. Therefore, the portion having a phase difference of 90 degrees in the circumferential direction from the point where the thread G has the highest thread height has a lower thread height. By configuring the thread G in this way, two types of spiral grooves are formed between the thread G: a virtual spiral groove structure that rotates clockwise and a virtual spiral groove structure that rotates counterclockwise. You can.

For details of the male threaded portion 54 in which two types of male threaded helical structures are formed, please refer to Japanese Patent No. 4,663,813 by the inventor of the present application. Note that the male threaded portion 54 is not necessarily limited to forming a right-handed thread and a left-handed thread, but has a lead direction that matches each other, and a lead angle set in the first male thread helical groove and a second thread with a different lead angle. A male thread spiral groove may be set.
Furthermore, as described above, the male threaded portion 54 has threads G alternately provided on one side and the other side in the diametrical direction, so that it has a non-circular shape that is approximately elliptical when viewed in the axial direction. .

Further, the relative rotation prevention member 30 has an inner circumferential surface 36 having a non-circular shape that substantially corresponds to the shape of the male threaded portion 54 when viewed in the axial direction. That is, as shown in FIG. 12, the inner circumferential surface 36 is arranged at a position where the engagement surface 36a that can interfere with the thread G of the male threaded portion 54 is about 90 degrees out of phase with respect to the engagement surface 36a. and an enlarged diameter surface 36b facing the thread G of the male threaded portion 54. That is, the engagement surface 36a may face the portion between the threads G along the circumferential direction of the male threaded portion 54 with respect to the male threaded body 50.
[0000]
Further, the unevenness 34a of the flange portion 34 has a saw blade shape. As shown in FIG. 12(b), the direction of the saw blade is set to allow rotation of the relative displacement prevention member 60 (see FIG. 13) in the tightening direction with respect to the male threaded body 50, and restrict rotation in the loosening direction. be done.

FIG. 13 is a sectional view showing the relative displacement prevention member 60 of the second embodiment. The relative displacement prevention member 60 has a left-handed helical thread portion 62 on its inner circumferential surface for screwing into the second male threaded helical groove 54b of the male threaded portion 54. Further, one end surface in the axial direction of the relative displacement prevention member 60 has a convex tapered shape that can come into surface contact with the end surface of the flange portion 34, similarly to the relative displacement prevention member 40 of the first embodiment. Moreover, a plurality of uneven portions 44 are formed along the circumferential direction on the one end surface. The direction of the saw blade of the uneven portion 44 is set in such a direction that it can engage with the uneven portion 34a. That is, the relative displacement prevention member 60 is set to allow rotation of the male threaded body 50 in the tightening direction and restrict rotation in the loosening direction.

The effect of the screw fastening structure of the second embodiment will be explained. As shown in FIG. 14(a), the fastened members 100 and 110 are inserted into the male threaded body 50, and the female threaded body 20 is tightened. At this time, the female threaded body 20 is rotated in the direction shown by arrow A, that is, in the tightening direction along the right-handed spiral, so that it spirals from the distal end side of the shaft portion 52 to the fastened members 100 and 110 side.

Next, the relative rotation prevention member 30 is inserted into the male threaded body 50. At this time, the relative rotation prevention member 30 and the male threaded body 50 are aligned in phase so that the enlarged diameter surface 36b faces the thread G. Then, the relative rotation prevention member 30 is displaced toward the head 12 side of the male threaded body 50 in the direction shown by the arrow in FIG. 14(b), that is, along the axial direction. At this time, the relative rotation prevention member 30 may be displaced to a position where the main body portion 32 is inserted into the engagement hole 24 as shown in FIG. 14(c).

Thereby, the relative rotation prevention member 30 engages with the male threaded body 50 and the female threaded body 20 in the circumferential direction. That is, since the engagement surface 36b (see FIG. 12) of the inner circumferential surface 36 is engaged with the thread G of the male threaded portion 52, the relative rotation prevention member 30 and the male threaded body 50 cannot rotate relative to each other. In this state, the member side unevenness 38 of the relative rotation prevention member 30 and the female thread side unevenness 26 of the engagement hole 24 of the female threaded body 20 fit and engage in the circumferential direction, creating a state in which relative rotation is not possible. Ru.

Next, the relative displacement prevention member 60 is screwed onto the male threaded body 50 and tightened. At this time, the relative displacement prevention member 60 rotates in the direction shown by arrow B in FIG. Spiral to the 110 side.

The relative displacement prevention member 60 approaches the relative rotation prevention member 30 by applying counterclockwise torque and tightening. Then, by further applying torque, the uneven portion 44 on the end face engages with the uneven portion 34a of the relative rotation prevention member 30 in the circumferential direction. The engagement structure formed by both members 30 and 60 allows relative rotation of the relative displacement prevention member 60 in the fastening direction, and restricts relative rotation in the loosening direction. As a result, the relative displacement prevention member 60 becomes unable to rotate relative to the relative rotation prevention member 30 in the loosening direction. Further, as described above, the relative rotation prevention member 30 is locked to the male threaded body 50 in the circumferential direction, so the relative rotation prevention member 30 and the relative displacement prevention member 60 rotate together with respect to the male threaded body 50. Can not. As a result, the relative displacement prevention member 60 has a structure that does not become mechanically loose.

Thereby, the male threaded body 50, the female threaded body 20, the relative rotation prevention member 30, and the relative displacement prevention member 60 are substantially integrated. That is, the inner circumferential surface of the relative rotation prevention member 30 is locked to the male threaded body 50 in the circumferential direction, and relative rotation with respect to the male threaded body 50 is restricted. Further, the outer circumferential surface of the relative rotation prevention member 30 is locked to the female threaded body 20 in the circumferential direction, so that relative rotation with respect to the female threaded body 20 is restricted. Therefore, the male threaded body 50 and the female threaded body 20 cannot rotate relative to each other through the relative rotation prevention member 30, and the female threaded body 20 has a structure that does not become mechanically loose.

Further, by tightening the relative displacement prevention member 60, the relative rotation prevention member 30 is sandwiched between the female threaded body 20 and the relative displacement prevention member 60, and displacement in the axial direction is regulated. In addition, the relative displacement prevention member 60 engages with the relative rotation prevention member 30 to restrict relative rotation in the loosening direction, and is in a state where it cannot be substantially separated from the relative rotation prevention member 30. 20 locking structures are constructed.

Similar to the screw fastening structure of the first embodiment, the screw fastening structure of the second embodiment has a structure in which the female thread body is fixed relative to the male thread body by inserting a relative rotation prevention member into the engagement hole of the female thread body. A screw fastening structure that does not loosen can be obtained.

In addition, by disposing the relative displacement prevention member at a location opposite to the female screw body with the relative rotation prevention member in between, displacement of the relative rotation prevention member in the axial direction is restricted and it is possible to remove it from the engagement hole. can be prevented. In addition, since the relative rotation prevention member and the relative displacement prevention member are engaged in the circumferential direction, it is possible to prevent the relative displacement prevention member from rotating in the direction of loosening, and the relative rotation prevention member and the relative displacement The prevention member can be substantially integrated.

In each of the embodiments described above, the outer shape of the head 12 is not limited to a hexagonal shape, but may be a constant width figure shape such as a circle or a Reuleaux polygon, a substantially elliptical shape, a rectangular shape, a star shape, etc. The head 12 may have a circular shape, and the top surface may have a groove (slot, etc.), a hole (cross recess, hexagonal hole, etc.) for engaging a fastening tool such as a screwdriver, etc. A convex shape may also be provided.

Although the engagement hole 24 has been described as having a tapered shape, it does not necessarily have to be tapered, and may be straight, curved, or curved, but it may be suitable for absorbing dimensional errors, etc. In this case, it is preferable to have a tapered shape.

Although the end face of the flange portion 34 of the relative rotation prevention member 30 is made into a concave tapered shape and the end face of the relative displacement prevention member 40 is made into a convex taper shape, at least the relative rotation prevention member 30 and the relative displacement prevention member 40 are It is sufficient that the end surfaces of the flange portion 34 engage with each other in the circumferential direction, and the end surface of the flange portion 34 is convex, that is, the end surface is a tapered surface whose diameter decreases toward the outside in the axial direction, and the end surface of the relative displacement prevention member 40 is concave. In other words, it may be a tapered surface that expands in diameter toward the outside in the axial direction. Of course, it goes without saying that the flange portion 34 is not necessarily necessary and may be omitted.

In the second embodiment described above, the size and number of the slits 37 can be set as appropriate. For example, the slits 37 may be formed at predetermined intervals along the circumferential direction, or may be formed at a part of the engagement surface 36a or the enlarged diameter surface 36b. It may be formed so that it is notched along the axial direction.

DESCRIPTION OF SYMBOLS 1... Screw fastening structure, 10, 50... Male thread body, 12... Head, 14... Shaft part, 15... Male thread part, 20... Female thread body, 22... Female thread part, 24... Engagement hole, 26... Female thread side unevenness, 30... Relative rotation prevention member, 32... Main body part, 34... Flange part, 36... Inner peripheral surface, 37... Slit, 38... Member side unevenness, 40, 60... Relative displacement prevention member, 100, 110... Fastened member.

Claims (8)

A fastening structure for a fastening body having a male threaded body and a female threaded body,
a relative rotation prevention member surrounding the male threaded body and inserted into the female threaded body ;
a relative displacement prevention member that is screwed onto the male threaded body and prevents relative displacement between the female threaded body and the male threaded body in the axial direction;
an engagement mechanism between the relative rotation prevention member and the relative displacement prevention member;
The male threaded body has a male threaded portion and a pair of male threaded side engaging portions that are opposed to each other across the axis and are formed by partially omitting the male threaded portion,
The relative rotation prevention member has an engagement surface that can come into surface contact with the male threaded side engagement part and interfere with the male threaded part, and an outer circumferential surface that can fit into the engagement hole of the female threaded body, and the Insert the male threaded body in a state where relative rotation is not possible,
A fastening structure characterized in that when the outer peripheral surface fits into the engagement hole, the engagement surface presses the male threaded portion radially inward . The fastening structure according to claim 1 , wherein the relative rotation prevention member has a non-circular insertion hole that substantially corresponds to the outer shape of the male threaded body when viewed in the axial direction. 3. The fastening structure according to claim 1 , wherein the outer circumferential surface has irregularities arranged in a circumferential direction. Any one of claims 1 to 3, wherein the outer circumferential surface has a tapered shape whose diameter decreases toward one end facing the female threaded body, and is in close contact with the tapered inner circumferential surface of the engagement hole. The fastening structure described above . The outer circumferential surface has a partially interrupted portion in the circumferential direction and is configured to be elastically deformable in the radial direction, and is pressed inward in the radial direction by the inner circumferential surface of the engagement hole, and the surrounding The fastening structure according to any one of claims 1 to 4, characterized in that the fastening structure is in close contact with the peripheral surface of the male threaded body. The engagement mechanism is characterized by comprising a plurality of protrusions and depressions arranged in the circumferential direction on the end face of the relative rotation prevention member and a plurality of protrusions and depressions arranged in the circumferential direction on the end face of the relative displacement prevention member. The fastening structure according to any one of claims 1 to 5 . The end surface of the relative rotation prevention member is a substantially annular first tapered surface that decreases or expands in diameter toward the outside in the axial direction,
The end surface of the relative displacement prevention member is a substantially annular second tapered surface that expands or contracts in diameter toward the outside in the axial direction,
7. The screw fastening structure according to claim 1, wherein the first tapered surface and the second tapered surface abut and engage in circumferential direction. The male threaded body has a first helical thread set at an appropriate lead angle and/or lead direction, and a second helical thread set at a lead angle and/or lead direction different from the first helical thread. ,
The female threaded body has a first helical groove that can be screwed into the first helical thread,
The fastening structure according to any one of claims 1 to 7 , wherein the relative displacement prevention member has a second helical groove that can be screwed into the second helical thread.