JP2023088227A - Anti-loosening fastening structure - Google Patents

Abstract

To provide an anti-loosening fastening structure capable of presenting an anti-loosening effect of a fastener consisting of a bolt member in which a simple locking projection is formed, or a nut member by using the fastener and a fixing washer.SOLUTION: In an anti-locking washer, a tabular fixing washer 6 is interposed between a fastened body 3 and a fastened body 3, a locking projection 4c including a step part in a front end in a fastening direction is formed on a surface opposed to the fixing washer 6. In the fixing washer 6, on one side, a slope part 6c from a low location to a high location in the same inclination direction of a lead angle is formed, and in the low location of the slope part 6c, an abutment part 6e to which the locking projection 4c is locked is formed at a position corresponding to the locking projection 4c in a fastener. When a fastening body is rotated in a fastening direction, the locking projection 4c is abutted to the abutment part 6e of the fixing washer 6. When the fastening body is rotated in a loosening direction, the locking projection 4c of the fastened body slides the slope part 6c of the fixing washer 6 and moves the fastening body in an axial direction, thereby performing anti-loosening operation.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-loosening fastening structure that prevents the fastener from loosening when objects to be fastened are screwed together using a fastener consisting of a nut and a bolt.

Nuts and bolts are widely used in various fields as fastening members for fastening and fixing parts and members. These nuts and bolts are used to fasten and fix parts and members, but there is a problem that the nuts and bolts loosen when vibrations are repeatedly applied to these fastening portions. Therefore, in order to prevent loosening of nuts and bolts, various structures have been proposed, such as a structure that prevents loosening using a double nut or a structure that prevents loosening using a washer.

Among these, as a locking structure using a washer, for example, Japanese Patent Application Laid-Open No. 2015-17657 (Patent Document 1), Japanese Patent Application Laid-Open No. 2011-220387 (Patent Document 2), and Utility Model Registration No. 3113151 The locking nut disclosed in (Patent Document 3) has a bearing surface of the nut and a surface of the washer with a plurality of inclined surfaces that allow the direction of rotation of the bolt, and a plurality of rotation preventing portions that prevent the rotation of the bolt. Whirl-stop is performed by forming and fitting into each rotation-preventing portion.

In addition, as another method of preventing loosening using a washer, a locking nut disclosed in Japanese Patent Application Laid-Open No. 10-153211 (Patent Document 4) has a ring-shaped washer with one surface of a gently inclined surface. When the nut is screwed and tightened, the nut is inclined by the inclined surface, thereby increasing the surface pressure on the bolt and preventing it from loosening.

Furthermore, in the locking structure of the fastener disclosed in Japanese Patent Application Laid-Open No. 2019-39555 (Patent Document 5), a washer is interposed between the head of the fastener and an object to be fastened, and the bearing surface of the washer is straight. and the angle of inclination of the joint face of the washer opposite to the bearing face of the washer and the joint face of the head of the fastener joined to this washer is 1.0 of the lead angle .theta.2 of the screw of the fastener. It is formed on a plane inclined at an angle of 0 to 3.0 times. When the fastener rotates in the loosening direction, the inclination of the joint surface of the head portion and the joint surface of the washer force the bearing surface of the washer to separate from each other and press against the object to be fastened, thereby increasing the frictional force of the fastener. Rotating displacement is prevented to prevent loosening.

JP 2015-17657 A JP 2011-220387 A Utility Model Registration No. 3113151 JP-A-10-153211 JP 2019-39555 A

The anti-loosening structure using a washer illustrated in Patent Documents 1 to 3 has an inclined surface and a rotation-preventing portion formed on the seating surface of the nut and the surface of the washer, and the rotation-preventing portion prevents rotation. When the nut is rotated to get over the inclined surface and fit into the rotation blocking part, the nut moves in the loosening direction in the axial direction, so that the locking action of the nut and the frictional force of the washer are reduced. For this reason, when vibration is repeated, the nut and the washer whose tightening force has decreased rotate together, resulting in a problem of losing the locking effect.

In addition, in the locking structure using a washer shown in Patent Document 4, one side of a ring-shaped washer is formed with a gently slanted surface, and the nut is inclined by this slanted surface to increase the surface pressure on the bolt. I have to. However, by inclining the nut, the bolt is forcibly bent, which increases the stress on the bolt, resulting in a problem of shortening the service life. In addition, if the entire surface of one side of the nut is not joined to the inclined surface of the washer, the nut will only contact a part of the washer, and the frictional force will be significantly reduced, resulting in the loss of the locking effect. becomes.

Furthermore, the anti-loosening structure disclosed in Patent Document 4 is said to exhibit anti-loosening effects because the axial force and the frictional force increase as the fastener rotates in the loosening direction. However, since the head joint surface of the fastener and the washer joint surface of the washer are inclined, when the inclined surfaces are formed by press working, pressure is applied to the punch of the die to incline due to the inclined surfaces. There is a problem that the life of the punch is significantly shortened due to the large stress generated in the punch.

The problem to be solved by the present invention is to provide an anti-loosening fastening structure capable of exerting an anti-loosening effect on the fastener by means of a fastener and a fixing washer comprising a bolt member or nut member having a simple locking projection. to do.

Therefore, the locking fastening structure according to the present invention is a fastening structure for fastening objects to be fastened with a fastener for screwing together a bolt member and a nut member, wherein a plate is provided between the object to be fastened and the object to be fastened. A fixed washer is interposed therebetween, and a locking projection having a stepped portion at the front end in the tightening direction is formed on the surface of the fastener facing the fixed washer, and the fixed washer faces the fastener. The fastener has a sloping portion extending from a low point to a high point in the same direction as the lead angle of the fastener, and an abutting portion for locking the locking projection at the low point of the sloping portion. and the other side is flat, and when the fastening body is rotated in the tightening direction, the locking projection abuts against the abutting portion of the fixed washer. and when the fastening body rotates in the loosening direction, the locking protrusion of the fastening body slides on the slope of the fixed washer to move the fastening body in the axial direction.

In addition, the inclination angle of the slant portion of the fixed washer and the inclination angle of the locking projection of the fastener are set to be equal to or less than the lead angle of the fastener.

Further, it is preferable that a plurality of the engaging projections formed on the fastening body and the sloped portions formed on the fixing washer are formed in a plurality of points symmetrically.

Furthermore, the joint area between the locking projection of the fastening body and the slope portion of the fixed washer is formed to be smaller than the joint area between the other surface of the fixed washer and the object to be fastened.

Moreover, it is desirable to form a sliding slope from a high place of the slope portion of the fixed washer in a direction opposite to the contact portion.

According to the present invention, a plate-shaped fixing washer is interposed between the objects to be fastened, and the surface of the fastener facing the fixing washer has a locking projection having a stepped portion at the front end in the tightening direction. Since the fixed washer has a sloped portion with the same inclination as the lead angle of the fastener on one side facing the fastener, the tightened fastener may be loosened due to vibration or the like. When the fastener is rotated, the locking projections of the fastener are separated from each other in the axial direction by the slope of the fixed washer. is pushed in the axial direction, the frictional force increases, and the axial force increases, so that the rotational displacement of the fastener is prevented. As a result, the fastener becomes immovable, so loosening of the fastener can be prevented.

In addition, by setting the angle of inclination of the slope of the fixed washer to be less than the lead angle of the fastener, even if the torque when the fastener rotates in the loosening direction due to vibration or the like is small, the gentle inclination can be maintained. Since the locking projection of the fastener slides on the surface, it presses between the fixed washer and the object to be fastened and between the male screw and the female screw to increase the frictional force and prevent the fastener from loosening. It is possible to demonstrate.

Furthermore, by forming a plurality of locking projections formed on the fastening body and slant portions formed on the fixing washer in a point-symmetrical manner, the fastening body can be moved parallel to the axis, and the fastening tool can be prevented from vibrating. When the fastener rotates in the loosening direction, the fastener moves smoothly with respect to the axis, so that the loosening preventing action of the fastener can be promoted.

Furthermore, since the joint area between the locking projection of the fastening body and the slanted surface of the fixed washer is formed smaller than the joint area between the other surface of the fixed washer and the object to be fastened, the fastener may be damaged by vibration or the like. When the fixing washer rotates in the loosening direction, the fixing washer becomes immovable due to friction with the object to be fastened.

In addition, since the sliding slope is formed in the opposite direction from the height of the slope portion of the fixed washer, when the fastening body is screwed and rotated in the tightening direction and the locking protrusion of the fastening body approaches, Even if the locking projection is at a position separated from the inclined portion, the locking projection slides on the sliding slope and reaches the inclined portion by rotating the fastening body. Rotational positioning means can be dispensed with.

It is a front view which shows the fastening state of the loosening prevention fastening structure in connection with this invention. It is a front view which shows the fastening body and washer of the locking fastening structure shown in FIG. It is a top view which shows a rotation washer. (A) to (C) are process diagrams showing a process of forming locking projections of a fastening body. It is a top view which shows the latching protrusion of a fastening body. It is a top view which shows a fixing washer. FIG. 7 is a cross-sectional view taken along the line AA of FIG. 6; FIG. 7 is a cross-sectional view taken along the line BB of FIG. 6; (A), (B), and (C) are explanatory diagrams showing the locking action. FIG. 4 is a cross-sectional view showing the state of the fastening body during locking action; FIG. 11 is a plan view showing a second embodiment of the fixing washer; 12 is a cross-sectional view taken along line CC of FIG. 11; FIG. (A) to (D) are explanatory diagrams showing the locking action in the second embodiment. It is a front view which shows the Example which applied the locking fastening structure in connection with this invention to the bolt member. It is a front view which shows the state which mount|wears a bolt member with a fixed washer.

The locking washer of the present invention is a fastening structure for fastening objects to be fastened by means of a fastener for screwing together a bolt member and a nut member, and a plate-like fixing structure is provided between the object to be fastened and the object to be fastened. A locking protrusion having a stepped portion at the front end in the tightening direction is formed on the surface of the fastener that faces the fixed washer with a washer interposed therebetween. A sloping portion extending from a low point to a high point in the same inclination direction as the lead angle of the fastener, and a contact portion for engaging the locking projection at the low point of the sloping portion are engaged with the fastener. The locking projection is formed at a position corresponding to the projection, and the other surface is formed flat. When the fastening body rotates in the loosening direction, the locking projection of the fastening body slides on the slope of the fixed washer to move the fastening body in the axial direction to prevent loosening. .

Embodiments of the present invention will now be described in detail with reference to the drawings. FIGS. 1, 2, and 3 show an embodiment of a locking washer according to the present invention, showing a state in which objects to be fastened are fastened by a nut member as a fastener. A substrate 1 made of, for example, a metal plate is formed with a through hole 1a, and a screw portion 2a of a bolt member 2 is inserted through the through hole 1a. A fastened object 3 made of a metal plate having a through hole 3a formed thereon is overlaid on the substrate 1, and a screw portion 2a of a bolt member 2 is inserted through the through hole 3a. The tip side of the threaded portion 2 a of the bolt member 2 protrudes from the body 3 to be fastened. The bolt member 2 is a general commercial product, and the bearing surface 2b of the head is surface-bonded to the base plate 1, and is immovable due to frictional action when tightened. A nut member 4 is screwed onto the threaded portion 2a of the bolt member 2 protruding from the member 3 to be fastened with a fixing washer 6 interposed therebetween. The head portion 4a of the nut member 4 is formed in the shape of a hexagonal nut having dimensions conforming to the standards of commercially available nuts.

A facing surface 4b of the nut member 4 that faces the object 3 to be fastened is formed with locking projections 4c at two points symmetrically with respect to the center. As shown in FIGS. 2 and 3, the locking projection 4c has a stepped portion 4d at its front end in the tightening direction of the nut member 4. As shown in FIGS. Further, the side surface of the locking projection 4c is formed in a substantially triangular shape, and the opposite surface 4b from the stepped portion 4d is formed with an inclined surface inclined in the same direction as the lead angle of the nut member 4. As shown in FIG. It is preferable to set the angle of the slant face to be equal to or less than the lead angle of the nut member 4 . Further, the height H1 of the locking projection 4c varies depending on the size and tightening torque of the nut member 4, but should be 0.2 mm to 1 mm for M3 to M30, and 0.5 mm to 3 mm for M30 or more. is preferred. The locking projections 4c are formed at two points symmetrical with respect to the center of the nut member 4, as shown in the drawing. Note that the locking projections 4c may be formed at two or more locations.

The locking projection 4c can be formed, for example, by a raised tool 5 as shown in FIG. The raising tool 5 is provided with a pressing portion 5a for forming the stepped portion 4d at the front end, and a forming portion 5b for forming the height and shape of the stepped portion 4d. The angle of the inner surface of the molded portion 5b is preferably set to be equal to or less than the lead angle of the nut member 4. As shown in FIG. Then, as shown in FIG. 4A, the raising tool 5 is brought into contact with the facing surface 4b of the nut member 4 at a predetermined angle. After that, as shown in FIG. 4(B), the meat is raised on the opposing surface 4b side and pressed until the meat fills the inner surface of the molded portion 5b. As a result, locking protrusions 4c are formed as shown in FIG. 4(C). The angle θ and the height H1 of the upper surface of the locking projection 4c are set by the molding portion 5b. Further, the stepped portion 4d is set substantially vertically by the angle of the pressing portion 5a, but is slightly inclined so that the thickness moves toward the inside of the forming portion 5b.

The width of the locking projection 4c formed in this way is smaller than the width of the inner edge and the outer edge of the screw hole of the nut member 4. The width may be the same as the dimension from the screw hole to the outer edge. The nut member 4 is generally formed by forging. A mold used for this processing is provided with recesses for forming the locking projections 4c on the facing surface 4b of the nut member 4, and the nut member 4 is formed in the usual manner. By performing forging, it is possible to form the locking projection 4c shown in FIG. 5(A). When the locking projection 4c is formed by forging, as shown in FIG. .theta. In the case of this embodiment, since two locking projections 4c are formed, each inclination angle .theta.1 is set to 1/2 of the lead angle so that the sum of the two inclination angles .theta. set to be the same as That is, it is desirable that each inclination angle θ1 be 1/the number of locking projections. The inclination angle θ1 may be set to a moderate angle up to 1/3 of the lead angle, which is 1/2 or less. Further, the locking projection 4c does not have to have the inclination angle .theta. as long as it slides on the slope portion 6c of the fixing washer 6, which will be described later.

The fixed washer 6 is preferably made of a metal plate made of a steel plate or a stainless steel plate having elasticity. The plate thickness of the fixing washer 6 varies depending on the diameter of the nut member 4, but is approximately 0.2 mm to 3 mm. As shown in FIG. 6, the fixing washer 6 is formed in a substantially circular shape larger than the outer diameter of the nut member 4, and has one surface 6a facing the nut member 4 that is attached to the locking projection 4c of the nut member 4 described above. Correspondingly, a height 6b is formed. Between the high place 6b and the one surface 6a, as shown in the AA cross-sectional view of FIG. formed. The inclination angle .theta.2 of the slope portion 6c is preferably half the lead angle when there are two slope portions 6c. For example, in the case of an M10 metric thread nut, the lead angle is defined as 3.02 degrees according to the JIS standard. Therefore, the inclination angle θ2 of the slope portion 6c is approximately 1.5 degrees. When the inclination angle .theta.2 is set, the locking projection 4c slides substantially at an angle of 3 degrees, which is twice 1.5 degrees, when there are two slope portions 6c. Therefore, the sum of the inclination angles of the inclined surface portion 6c formed on the fixed washer 6 is set to be equal to or slightly smaller than the lead angle. That is, it is desirable that each inclination angle θ2 be 1/the number of locking projections. The inclination angle θ2 may be set to a moderate angle up to 1/3 of the lead angle, which is 1/2 or less.

Moreover, the height H2 of the high portion 6b may be about 1/2 of the plate thickness of the metal plate. The other surface 6f of the fixing washer 6 is formed flat and is surface-bonded to the object 3 to be fastened. A through hole 6d is formed in the center of the fixing washer 6, through which the threaded portion 2a of the bolt member 2 is inserted. Further, a contact portion 6e is formed at a base end portion of the slope portion 6c opposite to the high portion 6b. The height H3 of the contact portion 6e is the same as the height of the height 6b.

The slant surface 6c of the fixed washer 6 is preferably formed by embossing, as shown in the BB cross-sectional view of FIG. 8, and formed in an arc concentric with the through hole 6d. When the sloped portion 6c is formed by embossing, the shape of the sloped portion 6c can be maintained when the nut member 4 is tightened. The slope portion 6c may be formed by half-blanking. Further, the contact portion 6e described above is also preferably formed by embossing or half-blanking.

In the nut member 4 and the fixed washer 6 configured as described above, the joint area where the locking projection 4c of the nut member 4 and the inclined surface portion 6c of the fixed washer 6 are in contact is It is formed to be smaller than the surface-bonded bonding area of the fastened body 3 . As a result, since the frictional force between the fixed washer 6 and the fastened body 3 is greater than the frictional force between the locking projection 4c and the slant surface 6c of the fixed washer 6, even when the nut member 4 rotates. , the fixed washer 6 is fixed to the object to be fastened 3 .

Next, the anti-loosening action of the above-described anti-loosening washer will be described. First, after inserting the through hole 6d of the fixing washer 6 into the threaded portion 2a of the bolt member 2 and placing it on the object to be fastened 3, the nut member 4 is screwed onto the threaded portion 2a of the bolt member 2, and as shown in FIG. As shown in A), the locking projection 4c of the nut member 4 is brought into contact with the slope portion 6c of the fixing washer 6. As shown in FIG. When the nut member 4 is a right-handed screw, when it rotates in the clockwise tightening direction indicated by the arrow, the locking projection 4c comes into contact with the contact portion 6e of the fixed washer 6 as shown in FIG. 9(B). When the nut member 4 is further rotated, the fixed washer 6 rotates a little like a general washer. The resistance increases and becomes fixed. Further, the nut member 4 is rotated to a predetermined tightening torque.

When external vibration is applied to the fastened body 3 and the nut member 4, the nut member 4 rotates counterclockwise in the loosening direction as indicated by the arrow in FIG. 9(C). As a result, the locking projection 4c of the nut member 4 slides on the slope portion 6c of the fixed washer 6 to move. At this time, since the fixing washer 6 has a large joint area with the object 3 to be fastened, it is surface-bonded to the surface of the object 3 to be fastened by frictional force, and is therefore in an immovable state. In addition, since it is known that the rotational torque of the nut member 4 in the loosening direction is significantly smaller than the frictional force between the fixed washer 6 and the fastened body 3, when loosening occurs, the nut member 4 only rotates in the counterclockwise loosening direction as indicated by the arrow in FIG. 9(C).

As the nut member 4 moves counterclockwise, the nut member 4 rises as indicated by the arrow in FIG. As a result, as shown in FIG. 10, the threads of both threaded portions 2a of the nut member 4 and the bolt member 2 are pressed, and the frictional force increases, thereby preventing rotation of the nut member 4 in the loosening direction. On the other hand, the fixed washer 6 is pressed toward the fastened body 3, increasing the frictional force. As a result, the nut member 4 rotates in the direction of loosening and tries to separate from the fixed washer 6, increasing the pressing force of both the screw portions 2a and increasing the frictional force between the fixed washer 6 and the fastened body 3. , when the nut member 4 tries to loosen, the anti-loosening action increases.

When loosening the nut member 4, it is preferable to simultaneously rotate the fixing washer 6 together with the nut member 4, so that it can be loosened easily like a general nut. Alternatively, when the nut member 4 is rotated counterclockwise in the loosening direction, it is initially difficult to loosen due to the above-described anti-loosening action. Since the frictional force is exceeded, the fixing washer 6 rotates together with the nut member 4, so that it can be easily loosened.

11-13 show a second embodiment of the fixing washer of the present invention. The same reference numerals as in the above-described embodiment indicate the same components, and detailed description thereof will be omitted. In the second embodiment, the fixed washer 10 forms a sliding slope 10g in the direction opposite to the contact portion 10e from the height 10b of the slope portion 10c.

As shown in FIG. 11, the fixing washer 10 is formed in a circular shape larger than the outer diameter of the nut member 4, and on one side 10a facing the nut member 4, two high points 10b are formed symmetrically with respect to the center. , between the high place 10b and the one side 10a, as shown in the CC sectional view of FIG. is formed. The inclination angle of the slope portion 10c is the same as that of the above-described embodiment shown in FIG. Moreover, the inclination angle of the sliding slope 10g may be about twice the lead angle of the nut member 4 or the like. Furthermore, the height of the height 10b is the same as that of the above-described embodiment. It is preferable that the slant surface 10c and the contacting portion 10e of the fixed washer 10 be formed by embossing or half-blanking as in the above-described embodiment.

Next, the operation of the second embodiment will be explained. First, similarly to the above-described embodiment, after inserting the through hole 10d of the fixing washer 10 into the threaded portion 2a of the bolt member 2 and placing it on the object to be fastened 3, the nut member 4 is inserted into the threaded portion 2a of the bolt member 2. , and the locking projection 4c of the nut member 4 abuts against the fixed washer 10, but as shown in FIG. . In this case, when the nut member 4 is rotated in the tightening direction, the locking projection 4c slides on the sliding slope 10g of the fixed washer 10, climbs over the height 10b, and as shown in FIG. 10c is reached. At this time, since the locking projection 4c of the nut member 4 does not press the fixed washer 10, it smoothly moves to the sliding slope 10g. In this manner, even if the locking projection 4c of the nut member 4 abuts against a portion other than the sloped portion 10c of the fixed washer 10, it is guided to the sloped portion 10c by the sliding sloped portion 10g. Therefore, when the nut member 4 is screwed onto the threaded portion 2a of the bolt member 2, it can be screwed together like a normal nut.

After the locking projection 4c of the nut member 4 reaches the inclined surface portion 10c, when the nut member 4 is rotated in the tightening direction, the locking projection 4c comes into contact with the fixing washer 10 as shown in FIG. 13(C). 10e. When the nut member 4 is further rotated, the fixed washer 10 is slightly rotated like a general washer. The resistance increases and becomes fixed. Further, the nut member 4 is rotated to a predetermined tightening torque.

When the object to be fastened 3 and the nut member 4 are externally vibrated, the nut member 4 rotates counterclockwise in the loosening direction as indicated by the arrow in FIG. 13(D). As a result, the locking projection 4c of the nut member 4 slides on the slope portion 10c of the fixed washer 10 to move. At this time, the fixed washer 10 is in an immovable state because it is surface-joined to the surface of the object 3 to be fastened by frictional force. In addition, since the rotational torque of the nut member 4 in the loosening direction is much smaller than the frictional force between the fixed washer 10 and the fastened body 3, only the nut member 4 can be loosened. It rotates in the counterclockwise loosening direction as indicated by the arrow in (D).

As the nut member 4 moves counterclockwise, the nut member 4 rises as indicated by the arrow in FIG. As a result, the threads of both the threaded portions 2a of the nut member 4 and the bolt member 2 are pressed, and the frictional force increases, so that the rotation of the nut member 4 in the loosening direction is prevented. It is pressed in the direction of the fastening body 3 and the frictional force increases. As a result, the nut member 4 rotates in the loosening direction and tries to move away from the fixed washer 10, increasing the pressing force of both threaded portions 2a and increasing the frictional force between the fixed washer 6 and the fastened body 3. As in the above-described embodiment, the locking action increases as the nut member 4 loosens.

14 and 15 show an example in which the locking washer of the present invention is applied to a bolt member 11 as a fastener. The fixing washer 6 or 10 shown in FIG. 6 or 11 is attached to the head portion 11a of the bolt member 11 shown in FIG. 14 on the screw portion 11b side.

A locking projection 11d is formed on the lower surface 11c of the bolt member 11 on the side of the threaded portion 11b facing the object to be fastened 3, similarly to the nut member 4 described above. The locking projections 11d are formed at two locations corresponding to the slant portions 10c formed on the fixed washer 10. As shown in FIG. Further, as shown in FIG. 15, the locking projection 11d has a stepped portion 11e formed at the front end thereof in the direction in which the bolt member 11 is tightened. A side surface of the locking projection 11d is formed in a triangular shape, and an inclined surface inclined in the same direction as the lead angle of the bolt member 11 is formed from the stepped portion 11e toward the lower surface 11c of the bolt member 11. It is preferable to set the angle of the slant face to be equal to or less than the lead angle of the bolt member 11 . Furthermore, although the height of the locking projection 11d varies depending on the size and tightening torque of the bolt member 11, it can be 0.2 mm to 1 mm for M3 to M30, and 0.5 mm to 3 mm for M30 or more. preferable. The locking projections 11d are formed at two points symmetrical with respect to the center of the bolt member 11, like the nut member 4 described above. Note that the locking projection 11d may be formed at two or more locations.

On the other hand, a screw hole 20a is formed in the substrate 20 made of a metal plate, and the screw portion 11b of the bolt member 11 is screwed into the screw hole 20a. A fastened object 3 made of a metal plate having a through hole 3a formed thereon is overlaid on the substrate 20, and a screw portion 11a of a bolt member 11 is inserted through the through hole 3a. A head portion 11 of the bolt member 2 is formed in a hexagonal shape having dimensions according to the standards of commercially available bolts.

Then, after inserting the fixing washer 10 into the threaded portion 11b of the bolt member 11 and inserting the threaded portion 11b into the through hole 3a of the object to be fastened 3, the threaded portion 2a of the bolt member 2 is inserted into the threaded hole 20a of the substrate 20. , and the locking projection 11 c of the bolt member 11 abuts against the fixed washer 10 . Further, when the bolt member 11 is rotated in the tightening direction, the locking projection 11c slides on the sliding slope 10g and the slope portion 10c of the fixed washer 10 as in the above-described embodiment, and eventually the bolt member 11 is moved to the predetermined position. When the tightening torque is reached, the fixing washer 10 is pressed against the surface of the object 3 to be fastened with a predetermined frictional force.

When the bolt member 11 is vibrated from the outside while the bolt member 11 is in a tightened state, the bolt member 11 tends to rotate counterclockwise in the loosening direction. As a result, the locking projection 11c of the bolt member 11 slides on the slope portion 11c of the fixed washer 10 to move. At this time, the fixed washer 10 is fixed to the fastened body 3 by frictional contact due to surface bonding. As a result, the bolt member 11 is lifted by the slope portion 11c, and the fixing washer 10 is pressed toward the object 3 to be fastened. As a result, as in the above-described embodiment, the pressing force of the threaded portions of the screw holes 20a of the bolt member 11 and the base plate 20 increases, and the frictional force between the fixed washer 10 and the fastened body 3 increases, so that the bolt Conversely, as the member 11 loosens, the locking action increases, as in the previous embodiment.

Although the present invention has been specifically described above based on the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist of the invention. Bolts and nuts are applicable to both JIS threads and inch threads, and are not limited. In addition to the hexagon bolt, the bolt member may be a hexagon socket head bolt, a countersunk head screw, a pan head screw, a butterfly screw, or a resin screw.

REFERENCE SIGNS LIST 1 substrate 2 bolt member 2a threaded portion 3 object to be fastened 4 nut member 4a head 4c locking projection 4d stepped portion 6 fixed washer 6a one side 6b height 6c inclined portion 6e contact portion 10 fixed washer 10g sliding slope 11 bolt member 11d locking projection

Claims (5)

A fastening structure for fastening an object to be fastened with a fastener for screwing together a bolt member and a nut member,
A plate-like fixing washer is interposed between the objects to be fastened and the objects to be fastened,
A locking projection having a stepped portion at the front end in the tightening direction is formed on the surface of the fastener facing the fixing washer,
The fixing washer has, on one surface thereof facing the fastener, a slope portion extending from a low portion to a high portion in the same inclination direction as the lead angle of the fastener, and the locking projection at a low portion of the slope portion. is formed at a position corresponding to the locking projection of the fastener, and the other surface is formed flat,
When the fastening body is rotated in the tightening direction, the locking protrusion is brought into contact with the contact portion of the fixed washer, and when the fastening body is rotated in the loosening direction, the body is locked. An anti-loosening fastening structure, wherein a protrusion slides on the slope of the fixed washer to move the fastening body in the axial direction. 2. The locking fastening structure according to claim 1, wherein the inclination angle of the slope portion of the fixed washer is less than or equal to the lead angle of the fastener. 2. The locking fastening structure according to claim 1, wherein a plurality of said locking projections formed on said fastening body and a plurality of slant portions formed on said fixed washer are formed point-symmetrically. 2. A locking device according to claim 1, wherein a joint area between said locking projection of said fastening body and said inclined surface portion of said fixed washer is formed to be smaller than a joint area between the other surface of said fixed washer and said object to be fastened. fastening structure. 2. The locking fastening structure according to claim 1, wherein a sliding slope is formed in a direction opposite to said contact portion from a high place of said slope portion of said fixed washer.

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