JP2005090530A - Locking fastening structure for piling member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a locking fastening structure for a plurality of piling members. <P>SOLUTION: A bush 8 vertically provided with a slit 10 is attached in a thin part in the form of an overturned cone having an eccentric through-hole 9 that is a little larger than a nominal diameter of a bolt 2. In a bolt through-hole 6 above a surface of a member to be fastened 4 on the side where a bolt head 2a is applied, a hole part 11 in the form of an overturned cone is bored having a taper surface of the same inclination angle to the inclination angle of the overturned cone of the bush 8. The bush 8 is inserted before fastening. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a loosening prevention fastening structure in a fastening method in which when a plurality of stacked members are fastened and integrated through fastening bolts, the fastening base of the fastening bolt is taken as one fastened material on the end side. It is.

For example, as a method of fastening a plurality of stacked materials of two or three, as shown in FIGS. 6a and 6b, a tap 3 as a screwing base of a fastening bolt 2 is cut on one fastening material 1 on the end side, and the like. Conventionally, a fastening method is performed by drilling a bolt through hole 6 in the material to be fastened 4 or 4 and 5. Since the protrusions can be gathered together and the nut 2 does not have to be applied to the opposite side of the head 2a of the bolt 2 (the material 1 to be fastened serves as a nut), the means adopted according to the working conditions is there.
If working conditions permit, although not shown in the drawings, the screw base may be reinforced by protruding the tip of the bolt 2 from the material to be fastened 1 and applying a nut. In the figure, reference numeral 7 denotes a washer applied to the fastened material 4 with which the two bolts 2a abut.

By the way, as described above, the structure in which the male threaded part and the female threaded part fasten the member to be fastened is referred to as “screw fastening body”, but the tensile force (axial force) in the male threaded part generated by fastening and the fastened member It is integrated with the compression force (tightening force) inside. The two forces are balanced when no external force is acting on the screw fastening body. The axial force and tightening force in this state are collectively referred to as “pretension”.
However, for some reason, the pretension of the screw fastening body may decrease. This is “screw loosening”.
The cause of the loosening of the screw is required for the failure of the contact portion and the action of repeated external forces. In FIG. 7, there are four contact portions: a threaded surface (A), seating surfaces (B and D) on both sides of the fastened member, and joint surfaces (C) of the fastened member. On the other hand, the repeated external forces are four in the axial direction external force (Wa), the axial perpendicular direction external force (Wi), the axial moment (Ma) and the bending moment (Mb). Pre-tension and repeated external force either individually or synergistically apply excessive force or generate stress somewhere in the contact area, thereby causing macro plastic deformation or slip, micro local plastic deformation or fretting. (Fine wear). As a result, the pretension is lost and the screw is loosened.
There are two types of screw loosening: a type that occurs when the screw does not rotate back and a type that occurs when the screw rotates back (Table 1).

The above "No return rotation" can be avoided with the correct tightening and pre-tension is not lost, but "With return rotation" is an axial force when severe vibrational external force is applied even with correct tightening. As a result of the decrease, “slack” occurs, and many proposals have been made to stop this “slack”.

  As for the report of the experimental results on the locking effect, a screw fastening body (screw nominal diameter: M10-P1.5) with various lockings applied to the test piece was used, and a vibrating force was applied in the direction perpendicular to the axis. The degree of decrease in axial force is compared. Hexagon nut with flange and nut with nylon ring are evaluated as practical.

The above results are analyzed as follows. That is, 40% of the torque applied when tightening the bolts and nuts is lost by friction on the screw joint surface and 40% is lost by friction on the seat joint surface. At most, 20% of the tightening torque is enlarged by the lead angle of the screw and converted into a tightening force. In screw fastening, friction control is the most important issue, and unless this is cleared, highly reliable screw fastening cannot be obtained. On the other hand, it is the effect of this friction that the tightened screw does not rotate in the loosening direction. When a large axial perpendicular force acts on the screw fastening body, it starts to slide on the seat surface of the bolt or nut. The screw joint surface also slides on the screw surface, which is a slope with a slope of the lead angle inclined by the half angle of the thread. Thus, when it begins to slide on a screw joint surface, the friction coefficient of a screw surface changes in the direction which becomes small. If the condition that the screw returns and rotates continuously with an external force perpendicular to the axis is satisfied, the bolts and nuts will loosen so rapidly that they will fall off.

  The above-mentioned good results of the flanged hexagon nuts are due to the friction of the “contact part b” in FIG. 7 described above, and the good results of the nuts with nylon rings are due to the friction of the “contact part a”.

  The thread-forming type tapping screw shown in FIG. 8 has the same mechanism as this nylon ring-containing nut and is excellent in preventing loosening, and this can not only save female thread processing costs. Since there is no fitting clearance between the male screw and the female screw, there is an effect of preventing the slippage of the screw surface, which is a concern when fitting ordinary screws. The above-mentioned flanged hexagon nut is uncertain because it depends on the state of “contact part b” (surface of the object to be tightened) in FIG. 7, and in order to prevent screw loosening with return rotation, The only countermeasure is to ensure the frictional resistance of the mating part.

  In spite of having a fitting clearance between the male screw and the female screw, a so-called “pitch loss” is to form a high frictional resistance to prevent screw loosening. The mechanism will be described below with reference to FIGS.

In the drawing, A indicates a male screw and B indicates a female screw of a nut.
FIG. 9 shows the case where the nut is loosened, and the upper slope B-1 of the thread half-angle of the female screw B comes into contact with the lower slope A-1 of the thread half-angle of the male thread of the bolt, and the opposite side is based on the fitting gap. A gap C is formed. The adjacent pitches P ₁ and P ₂ are P ₁ = P ₂ . FIG. 10 shows that when the nut is loosened, the lower slope B-2 of the thread half angle of the female screw B is in contact with the upper slope A-2 of the thread half angle of the male thread of the bolt, and the opposite side is based on the fitting clearance. A gap C is formed. The adjacent pitches P ₁ and P ₂ are P ₁ = P ₂ .

FIGS. 9 and 10 show the case where P ₁ = P ₂ without any pitch loss, but FIG. 11 shows the time when the nut is loosened when a device is intentionally made to change the pitch (P ₁ > P ₂ ). And the three-point contact pressure becomes irregular, and the loosening of the nut is hindered by the contact pressure between the uppermost B-1 and A-1. This is the so-called pitch loss, and the double nut is also a locking mechanism based on this principle. In addition, pitch loss can be formed by adding a forcible bending posture to the nut or bolt.

  From the above point of view, when examining the “screw fastening body” shown in FIG. 6, it is clear that almost no “loosening prevention” effect can be expected.

  The problem to be solved is to improve the low anti-loosening capability in the case where the plurality of stacked materials described above are fastened and integrated through fastening bolts.

  The multi-layered material loosening-fastening fastening structure of the present invention includes a bush having a slit formed vertically in a thin portion of an inverted cone having an eccentric through hole slightly larger than the nominal diameter of the bolt, and a bolt An inverted conical hole portion having a tapered surface having the same inclination angle as the reverse cone inclination angle of the bush is drilled from the surface of the material to be fastened on the side in contact with the head to the upper part of the bolt through hole, and the bush is inserted. It is characterized in that it is fastened in a state.

  In the fastening structure of the present invention, when the object to be fastened is tightened, the bolt tightening force acting on the upper end of the bush via the bolt head or the interposed washer is applied to the missing circle slit. As the gap becomes smaller, the reverse conical cylindrical piece of the bush is reduced in diameter, and the bush is filled as if it is a clogging material between the reverse conical hole at the top of the bolt hole and the bolt. The bush is in a state of being pinched, and the material to be fastened and the bolt on the side where the bolt head abuts are firmly integrated via the bush. At this time, the male screw of the bolt bites into the bush, which has the same effect as the tapping screw introduced in FIG. Furthermore, when the reduced-diameter bush is fitted into the inverted conical hole, the thick part of the eccentrically formed bush is locally pressurized, increasing the clogging effect of the bush and increasing the bolt and bolt head. The frictional force acting on both of the materials to be fastened on the abutting side increases. At this time, a pitch loss effect is also generated. Further, the side pressure applied to the upper portion of the bolt 2 in a deflected manner causes the bolt 2 to bend and deviates the pitch with the tap 3 of the material 1 to be fastened, thereby generating pitch loss. Thus, the tapping screw effect and the pitch loss effect are produced at the upper part, and the pitch loss effect is produced at the lower part, thereby improving the effectiveness of the loosening prevention.

A simple and versatile locking structure with a locking mechanism has been realized.

  FIG. 1 is a development view of the fastening structure of the present invention, in which 8 is a bush, and in the illustrated example, an inverted conical ring having an eccentric through hole 9 slightly larger than the nominal diameter of the bolt 2. The thin-walled portion is formed by vertically arranging a slit 10 for a missing circle.

  From the surface of the material to be fastened 4 on the side where the head 2a of the bolt 2 abuts to the upper part of the bolt through hole 6, an inverted conical hole portion having a tapered surface having the same inclination angle as the inverse cone inclination angle of the bush 8 in advance. 11 is perforated.

Thus, the bush 8 is fitted into the inverted conical hole 11 in the lower half locking posture with the upper half protruding, and the bolt 2 is fastened.

The fastening manner is shown in FIG. That is, when the bush 8 is pushed into the inverted conical hole 11 by the screwing of the bolt 2, the gap of the cutout slit 10 is reduced, the bush 8 is reduced in diameter, and the reverse conical hole 11 and the bolt are reduced. The bush 8 is inserted as if it is a clogging material between the bush 2 and the bush 8 and the bolt 8 is sandwiched between them. The material to be fastened 4 and the bolt 2 are firmly integrated with each other through the bush 8 to achieve the tapping screw effect. Play.

At this time, when the bush 8 having a reduced diameter is fitted into the inverted conical hole portion 11 as the bolt 2 is screwed, the thick portion 8a of the bush 8 formed eccentrically becomes a bolt from the radial direction. The frictional force acting on both the bush 8 and the bolt 2 increases due to the local wedge effect on the circumference. At this time, the bending applied to the bolt 2 brings about a pitch loss effect. On the other hand, at the lower part of the bolt 2, when the bolt 2 is bent, a tap loss effect is generated, and the strong friction portions generated at the upper and lower sides achieve locking prevention.

  In the illustrated example, the washer 7 is interposed, but the bush 8 must be pushed in place of the bolt head 2a, and its inner diameter must be on the upper surface of the bush 8. The cutout slit 10 has variations other than vertical (straight).

  For example, the slit 10 for the missing circle of the bush 8 is formed so as to be inclined in the direction opposite to the spiral direction of the screw portion 2b of the bolt 2. When the slit 10 for the cutout circle of the bush 8 is inclined in the direction opposite to the spiral of the bolt 2, the edge of the slit 10 is almost orthogonal to the brake action when the "returning rotation" force is applied, thereby preventing the loosening effect. To increase.

Further, the cutout slit 10 of the bush 8 may be formed to be inclined in the same direction as the spiral direction of the bolt 2.
The helical tightening torque accompanying the progress of the screwing of the bolt 2 is guided by the inclined slit 10 of the bush 8 and the bush 8 is immediately reduced in diameter uniformly. Diameter and “tightening axial force” are facilitated.

  As shown in FIG. 3, the inclination angle θ of the cutout slit 10 of the bush 8 is preferably set to about 20 ° to 25 ° with respect to the bolt shaft. As a result, the end edge of the slit 10 for the cutout circle is evenly contacted with the screw portion 2b of the bolt 2 with a certain phase difference, and the bushing 8 is smoothly reduced in diameter by the tightening torque applied in a spiral shape. can do.

The width S of the cutout slit 10 of the bush 8 may be a width having a gap in a state where the bolt 2 is tightened.
Since the width of the cut-out slit 10 is set so that the end face of the cut-out slit 10 of the bush 8 has a gap in the closed state, an inverted conical shape is obtained even in the closed state. It is possible to maintain a strong spring force of the bush 8 in a state of being sandwiched between the hole 11 and the bolt 8 and achieve a strong integration.

  The bush 8 may be formed of a synthetic resin. In the case of using in a place where corrosion is severe, the advantage of the synthetic resin which is rich in elasticity and exhibits a strong loosening prevention effect can be used depending on the purpose of use and the situation of use.

As shown in FIG. 2, the pushing of the bush 8 is often performed through the washer 7 in terms of the surface protection of the material to be fastened 4.
Therefore, if the bush 8 is configured with a washer 7 without being configured with a simple ring, the construction is also facilitated.

The assembly procedure shown in FIGS. 4A and 4B is such that a leg 12 for inserting the washer 7 is provided close to the inner diameter of the upper surface of the bush 8, and the washer 7 is inserted into and crimped into the through-hole 7a using an extended urging force. The bush 8 with the washer 7 is integrated.
When tightening, the bush 8 is automatically separated from the washer 7 by reducing the diameter.
Benefit from parts management.

4 with a washer 7 is a separated configuration, but can also be integrated.
As the expanded biasing force increases, the effect of integration with the inverted conical hole 11 increases.

That is, the bush 8 ″ shown in FIG. 5 has an eccentric through hole slightly larger than the nominal diameter of the bolt in the washer portion 7 ′, and the diameter is reduced around the through hole 9 ′ in the lower direction of the bolt axis. An inverted conical cylindrical piece 13 is suspended, and a washer part 7 ′ and an inverted conical cylindrical piece 13 are formed to form a cutout slit 10 ′ continuous.
Since the diameter of the washer portion 7 ′ is integrally reduced with the inverted conical cylindrical piece 13, the urging force that greatly expands as the bush 8 ″ is increased and the contact pressure to the opposite conical hole portion 11 is increased.

  When multiple stacking materials are fastened and integrated through fastening bolts, the loosening prevention failure in the fastening method in which the fastening base of the fastening bolt is taken as one fastening material on the end side is eliminated, It is conceivable that the troublesomeness is eliminated.

It is construction procedure explanatory drawing of this invention fastening structure. (Example 1) It is this invention fastening structure explanatory drawing. (Example 1) It is explanatory drawing of the bush in this invention. (Example 1) a and b are assembly procedure diagrams of the bush in the present invention. (Example 2) It is explanatory drawing of the bush in this invention. Example 3 a and b are explanatory drawings of a conventional fastening structure. It is a simplified model of a screw fastening body. It is a tapping screw explanatory drawing. It is pitch loss explanatory drawing. It is pitch loss explanatory drawing. It is pitch loss explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fastening material 2 Fastening bolt 2a Bolt head 2b Screw part 3 Tap 4 Fastened material 6 Bolt through-hole 7 Washer 7a Through-hole 8 Bush 8 'Bush 8 "Bush 8a Thick part 9' Through-hole 10 Notch-circle slit 10 ' Slit for cutout 11 Reverse conical hole 12 Leg 13 Reverse conical cylindrical piece

Claims (8)

A bush with vertical slits attached to the thin part of the inverted conical body with an eccentric through hole slightly larger than the nominal diameter of the bolt is attached, and the bolt through-hole from the surface of the material to be fastened on the side where the bolt head abuts A multi-stacked material characterized in that an inverted conical hole portion having a tapered surface having the same inclination angle as the reverse cone inclination angle of the bush is drilled in the upper portion and fastened with the bush interposed therebetween The anti-loosening fastening structure. The multi-layered material loosening-fastening structure according to claim 1, wherein the slit for the cutout circle of the bush is formed so as to be inclined in a direction opposite to the spiral direction of the screw portion of the bolt. The multi-layered material loosening-fastening structure according to claim 1, wherein the slit for the cutout circle of the bush is formed so as to be inclined in the same direction as the spiral direction of the screw portion of the bolt. The multi-layered material loosening-stop fastening structure according to claim 1, wherein an inclination angle of the slit for the cutout circle of the bush is set to approximately 20 ° to 25 ° with respect to the bolt shaft. The multi-layer material loosening-fastening structure according to claim 1, wherein a width of the slit for the cutout circle of the bush is a width having a gap in a state where the bolt and the nut are tightened. The multi-layered material loosening-fastening structure according to claim 1, wherein the bush or nut is formed of a synthetic resin. A bushing with a washer is used by projecting a leg portion for inserting the washer 7 near the inner surface of the bush and integrating it by inserting and pressing it into the through hole of the washer using an extended biasing force. The multi-layered material loosening-fastening structure according to claim 1, wherein: The washer part has an eccentric through hole that is slightly larger than the nominal diameter of the bolt, and an inverted conical cylindrical piece that is reduced in diameter in the bolt axial direction downward is suspended around the through hole, and the washer part and the reverse cone 7. A multi-layered material loosening-fastening structure according to claim 1, wherein a bush formed by forming a slit for a continuous circle in a cylindrical piece is used.

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