JP2005114055A - Centering mechanism of loosing preventive part in screw fastening body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a conical body capable of reducing the diameter thereof to accurately and tightly fit to a conical hole section with a tapered face having the same inclination angle as the cone inclination angle. <P>SOLUTION: A tapered face front end section of the conical hole section 1b with the tapered face having the same inclination angle as the cone inclination angle of the conical body capable of reducing the diameter thereof tightly fit thereto is a substantially linear hole section 7. An edge section 8 is formed with which a front section of the conical body capable of reducing the diameter thereof can make point contact. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a bushing body in which a slit is provided vertically in a thin wall portion of a cone having an eccentric through hole slightly larger than the nominal diameter of the bolt proposed by the present applicant as a part for preventing loosening in a screw fastening body. The present invention also relates to a centering mechanism for mounting the conical hole portion having a tapered surface having the same inclination angle as the conical inclination angle of the bush body as a receiving portion with an accurate posture.

The structure in which the male screw part and female screw part fasten the member to be fastened is called a “screw fastening body”, but the pulling force (axial force) in the male screw part generated by tightening and the compression force in the fastened member ( Integrated by tightening force). 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. 3, there are four contact portions: a threaded surface (A), seat 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 the four in the axial direction external force (Wa), the axial perpendicular direction external force (Wi), the moment about the axis (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: the type that occurs when the screw does not rotate back and the 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 the axis when severe vibrational external force acts even with correct tightening. Many proposals have been made to stop the “loosening” because the force is reduced to cause “loosening”.

    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 surface, which is a slope with a slope of the lead angle inclined at the half angle of the thread, also slides. 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 good performance of the described hexagon nut with a flange is due to the friction of the “contact portion b” in FIG. 3 described above, and the good performance of the nut with a nylon ring is due to the friction of the “contact portion a”.

  The thread forming type tapping screw shown in FIG. 4 has the same mechanism as this nylon ring-containing nut and is excellent in preventing loosening. 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. In the above-mentioned flanged hexagon nut, it is uncertain depending on the state of “contact part b” (the surface of the object to be tightened) in FIG. The only countermeasure is to secure the frictional resistance of the screw fitting 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. 5 shows a state in which the upper slope B-1 of the screw thread half-width of the female screw B is in contact with the lower slope A-1 of the thread half-width of the male thread of the bolt, and the gap based on the fitting gap is on the opposite side. C is formed. The adjacent pitches P1 and P2 are P1 = P2. FIG. 6 shows that when the nut is loosened, the lower slope B-2 of the thread half angle of the female thread 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 P1 and P2 are P1 = P2.

  FIGS. 5 and 6 are cases where there is no P1 = P2 pitch loss, but when the nut is loosened when a device is intentionally made to change the pitch (P1> P2), FIG. 7 shows three points. The contact pressure becomes irregular, and the looseness 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.

The present applicant has also proposed a series of locking devices.
That is, in Japanese Patent Application No. 2003-521647, it is a locking fastener and has a bolt and an eccentric bolt through-hole slightly larger than the nominal diameter of the bolt at the base, A washer in which a conical cylinder piece whose diameter is reduced along the upper direction of the bolt axis is erected, and a base part and a slit for a continuous circle formed in the conical cylinder piece are formed in the thin part of the cylinder piece, Make the inner diameter of the half that is not smaller than the diameter of the outer circumference of the tip of the conical tube piece of the washer, and the diameter of the opening of the half that faces the washer is the base of the cone tube piece of the washer A conical hole having a taper surface having the same inclination angle as the inclination angle of the conical cylinder piece of the washer, which is smaller than the diameter of the outer circumference of the washer and slightly higher than the height of the conical cylinder piece of the washer, is a screw part of the bolt. From the nut opened at the bottom of the female thread This has been proposed as shown in FIGS.

That is, FIGS. 8 and 9 show the nut 1 and the washer 2, respectively. As shown in FIG. 8, the nut 1 has a conical tube of the washer 2 below the female screw portion 1a that is screwed with the screw portion of the bolt. A conical hole 1b for fitting the piece 2a is provided. The inclination angle θ of the conical hole 1b is set to the same angle as the inclination angle θ of the conical cylinder piece 2a. An inner collar-shaped step 1c is provided between the female thread 1a and the conical hole 1b.
The conical hole portion 1b has an inner diameter of a half portion that does not face the washer 2 smaller than an outer diameter diameter of the tip portion of the conical cylindrical piece 2a, and the opening of the half portion that faces the washer 2 The diameter is made smaller than the diameter of the outer periphery of the base portion of the conical cylindrical piece 2a.
Further, as shown in FIG. 9, the washer 2 has an eccentric bolt through hole 2c slightly larger than the nominal diameter of the threaded portion through which the threaded portion of the bolt penetrates in the center of the circular flat base portion 2b. Around the bolt through hole 2c, the above-mentioned conical cylindrical piece 2a that is reduced in diameter toward the tip of the bolt shaft is erected.
The thin-walled portion 2d of the conical cylinder piece 2a is formed with a base 2b and a slit 2e for lacking circle that is continuous with the conical cylinder piece 2a.
Thus, the nut 1 and the washer 2 are fitted as shown in FIG.
The fastening with this fitting body is shown in FIG.
The slightly eccentric thick part 2f of the conical cylindrical piece 2a fitted in the conical hole part 1b presses the bolt 3 from the radial direction (arrow F1), and is slightly inclined when pressed by the thick part 2f. The bolt 3 to be inclined is pressed by the female thread 1a of the nut 2f from the radial direction opposite to the thick part 2f (arrow F2). The pressing force (F1, F2) from the direction is applied, and a large loosening prevention effect (pitch loss effect) is exhibited.
Further, the thickened portion 2f of the conical cylindrical piece 2a fitted into the conical hole portion 1b of the nut 1 has a wedge-like effect of pressing the bolt 3 from the radial direction, so that the tip portion in the bolt axial direction is more than the washer 2. A force (arrow F3) that presses the screw portion 3a of the bolt from the entire circumference is applied to the female screw portion 1a of the nut 1 that is screwed, and the frictional force applied to the screw threads of both the nut 1 and the bolt 3 is increased. The integration of the bolt 3 and the nut 1 is made strong (F3 is effective in pitch loss, but in this portion, the bolt screw portion 3a generated by the wedge effect is connected to the conical cylindrical piece 2a. The biting has a tapping screw effect, and in addition to this, when the base portion 2b of the washer 2 is pushed down by the nut 1, the friction of the contact portion b in FIG. The force is on the nut 1 Bring Pitchirosu effect in part. In which exerts such a complex multifaceted locking ability.).
In addition, 4 and 5 in a figure show a to-be-clamped thing.

Further, in Japanese Patent Application No. 2003-134013, a bolt, a bush in which a slit for a missing circle is vertically formed in a thin wall portion of a cone having an eccentric through hole slightly larger than a nominal diameter of the bolt, and a bearing surface are opposed to each other. The inner diameter of the inner half of the bush is smaller than the outer diameter of the tip of the bush, and the diameter of the opening of the half facing the seat is smaller than the outer diameter of the lower part of the bush. A conical hole portion having a tapered surface having the same inclination angle as the inclination angle is proposed, which is composed of a nut opened at a lower portion of a female screw portion to be screwed with a screw portion of a bolt.
That is, as shown in FIGS. 12 to 13, a bolt 3 and a bush 6 in which a slit 6 c for a missing circle is provided vertically in a thin portion 6 b of a conical body having an eccentric through hole 6 a slightly larger than the nominal diameter of the bolt 3. The diameter of the inner periphery of the half portion not facing the seating surface is made smaller than the diameter of the outer periphery of the tip portion of the bush 6, and the diameter of the opening of the half portion facing the seating surface is The nut 1 is formed at the lower portion of the female screw portion 1a that is smaller than the diameter and has a tapered surface having a tapered surface having the same inclination angle as the conical inclination angle of the bush 6 and screwed with the screw portion 3a of the bolt 3. .
With this, the fastened members 4 and 5 shown in FIG. 12 are attached to the perforations 4a and 5a via the bolts 3 inserted therein, and tightened.
Then, as shown in FIG. 13, when the fastened members 4 and 5 are tightened, the tightening force of the nut 1 is applied to the slit 6c for the missing circle, and the gap of the slit 6c for the missing circle becomes smaller. The bush 6 is reduced in diameter, and the bush 6 is interposed between the conical hole 1 b of the nut 1 and the bolt 3 as if it is a clogging material, and the bush 6 is sandwiched between the nut 1 and the bolt 3. The nut 1 and the bolt 3 are firmly integrated through the bush 6.
At this time, when the bush 6 having a reduced diameter is fitted into the conical hole 1b of the nut 1 as the bolt 3 and the nut 1 are screwed together, the thickness and thickness of the bush 6 formed eccentrically are reduced. 6d and 6b strongly pressurize the bolt 3 from the radial direction, and the frictional force acting on both the bush 6 and the bolt 3 increases due to the local wedge effect on the circumference.
Specifically, the nut 1 is inclined so as to ride on the thick portion 6d of the bush 6, and the lower end of the nut 1 is strongly pressed locally against the thick and thin portions 6d and 6b of the bush 6 and the upper end of the nut 1 is bolt 3 Strongly pressed locally on the symmetrical part of the shaft, and here, pressing forces P, P ′ from the radial direction facing each other above and below the three bolt axes
Is added to the bolt 3, and the effect of preventing the nut 1 from being loosened is improved.
That is, at the upper end of the nut 1 with strong concentrated friction and the nut 1, the so-called pitch loss phenomenon consisting of pitch mismatch due to the inclined posture pressing of the nut 1 will ultimately enhance the “return rotation” blocking ability. (Same as in FIG. 11).

Furthermore, in Japanese Patent Application No. 2003-320782, when a plurality of stacked members are fastened and integrated through fastening bolts, the fastening base of the fastening bolt is taken as one fastening material on the end side. Proposals are made on the loosening-fastening structure in the law. In other words, a bush with a slit in the vertical direction is attached to a thin part of an inverted cone having an eccentric through hole that is slightly larger than the nominal diameter of the bolt, and the bolt from the surface to be fastened on the side where the bolt head abuts Anti-loosening of a plurality of stacking materials formed by drilling a reverse conical hole portion having a tapered surface having the same inclination angle as the reverse cone inclination angle of the bush with respect to the upper portion of the through hole, and fastening with the bush interposed therebetween Fastening structure.
FIG. 14 is a developed view of the fastening structure, wherein 6 is a bush, and in the illustrated example, a thin-walled portion of an inverted conical ring having an eccentric through-hole 6a slightly larger than the nominal diameter of the bolt 3 6b is formed by vertically providing a slit 6c for a missing circle.
From the surface of the material to be fastened 4 on the side where the head 3b of the bolt 3 abuts to the upper part of the bolt through hole 4a, an inverted conical hole portion having a tapered surface having the same inclination angle as the inverse cone inclination angle of the bush 6 in advance. 4b is perforated.
Thus, the bush 6 is fitted into the inverted conical hole 4b in the lower half locking posture in which the upper half protrudes, and the bolt 3 is fastened.
The fastening manner is shown in FIG. That is, when the bush 6 is pushed into the inverted conical hole 4b by the screwing of the bolt 3, the gap of the cut-out slit 6c is reduced, the bush 6 is reduced in diameter, and the reverse conical hole 4b and the bolt are reduced. The bush 6 is interposed as if it is a clogging material, and is sandwiched between the bushes 6. The material to be fastened 4 and the bolt 3 are firmly integrated with each other through the bush 6, and the tapping screw effect is obtained. Play.
At this time, when the bush 6 having a reduced diameter is fitted into the inverted conical hole portion 4b as the bolt 3 is screwed, the thick portion 6d of the bush 6 formed eccentrically becomes a bolt from the radial direction. The frictional force acting on both the bush 6 and the bolt 3 increases due to the local wedge effect on the circumference. At this time, the bending applied to the bolt 3 brings about a pitch loss effect. On the other hand, at the lower part of the bolt 3, the pitch loss effect is generated by bending the bolt 3, and the strong frictional portions generated at the top and bottom achieve the locking.
In the figure, reference numeral 5a denotes a screw hole tapped in advance on the fastened material 5 side as a screwing base of the bolt 3.

The above proposals are based on the premise that a conical body having a diameter that can be reduced is accurately closely fitted to a conical hole portion having a tapered surface having the same inclination angle as that of the cone inclination angle. Under the absence of a guide, accurate fitting under the high friction state in which the surfaces are in contact with each other (because the cone presses against the conical hole portion with obstacles) is difficult to expect.
That is, when this is shown in the case of the nut 1 and the bush 6, as shown in FIGS. 16 a and 16 b, it is not guided by a separate guide means due to the nonuniform friction degree of the contact surfaces of the surfaces. The bush 6 is easy to tilt without taking an accurate posture.

  Such a situation makes the effects of the proposals unsatisfactory and needs to be resolved.

  The present invention provides a cone having an adjustable diameter, with the tapered tip of the conical hole having a taper surface having the same inclination angle as the cone inclination angle to which the diameter-reducible cone is closely fitted as a substantially straight hole. It is characterized in that an edge portion capable of making point contact with the tip portion of the body is formed.

The close contact between the planes is resolved. That is, the cone whose tip is expanded without being constrained by the tapered surface is constrained in a support state in which only the edge portion is in point contact.
Under such point support, the balance works automatically and the cone is accurately centered.
Therefore, the fitting with the exact attitude | position with respect to the conical hole part of a cone can be expected.

FIG. 1 shows an embodiment of the present invention applied to a nut 1, and a tapered tip end portion of a conical hole portion 1 b is formed as a substantially straight hole portion 7, whereby an edge portion 8 is formed.
As shown in FIG. 2, when the bush 6 is inserted into the hole 7, the bush 6, which has lost the constraining taper surface at the tip, expands the tip, and thus makes point contact at the edge 8. Fit into the aspect.
The pushing of the bush 6 under such a support state realizes an accurate posture of the bush 6 by acting a balance ability.

  As a part to prevent loosening in a screw fastening body, a bushing body in which a slit for a missing circle is vertically formed in a thin part of a cone having an eccentric through hole slightly larger than the nominal diameter of the bolt proposed by the present applicant is formed at a receiving part. This is extremely significant as a centering mechanism for mounting the bush body with a precise posture on a conical hole portion having a tapered surface having the same inclination angle as the cone inclination angle of the bush body.

It is explanatory drawing of this invention mechanism. It is operation | movement explanatory drawing of this invention mechanism. It is a simplified model diagram of a screw fastening body. It is explanatory drawing of a tapping screw. It is explanatory drawing of pitch loss. It is explanatory drawing of pitch loss. It is explanatory drawing of pitch loss. It is explanatory drawing of the nut of this invention object. a and b are a plan view and a front view of the washer of the present invention. It is fitting explanatory drawing of the nut and washer of FIG. It is explanatory drawing of the fastening body using the components shown in FIG. It is expansion | deployment explanatory drawing of another screw fastening body. It is fastening condition explanatory drawing of the thing of FIG. It is expansion | deployment explanatory drawing of another screw fastening body. It is fastening aspect explanatory drawing of the thing of FIG. a and b are explanatory diagrams of defects in the non-implementation of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nut 1a Female thread part 1b Conical hole part 1c Step part 2 Washer 2a Conical cylinder piece 2b Base part 2c Bolt through-hole 2d Thin part 2e Slit part 2f Thick part 3 Bolt 3a Screw part 3b Head 4, 5 Covered Fastening member 4a, 5a Perforation 4b Reverse conical hole portion 6 Bush 6a Eccentric through hole 6b Thin wall portion 6c Cutout slit 6d Thick portion 7 Hole portion 8 Edge portions P, P 'Pressing force

Claims (1)

The tip of the tapered surface of the conical hole portion having a tapered surface having the same inclination angle as the cone inclination angle to which the diameter-reducing cone is closely fitted is formed as a substantially straight hole portion. A centering mechanism for a part for preventing loosening in a screw fastening body, wherein an edge portion capable of point contact with a tip portion is formed.

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