JPH1089333A - Idle rotation stopping structure of bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely avoid idle rotation of a bolt and reduce costs by reducing assembling manhours at a factory. SOLUTION: An insertion hole 16 opened at the planer tip part 7 of a tension rod 2 to be a fastening object is provided with a pair of small opening curved surface parts having small radii of curvature and a pair of large opening curved surfaces 21, 21 which are cocentrically arranged and have large radii of curvature. A pair of small oepning curved surface parts are arranged symemtrically with respect to the radii of curvature center of a pair of the large opening curved surface parts 21, 21. A pair of small opening curved surface parts are located so as not to interfere with the outer peripheral surface of the serration part 6 of the bolt 3. A pair of large opening curved surface parts 21, 21 are formed along a circle of the radius which is a little smaller than the outer peripheral surface of the serration part 6. The serration part 6 is engaged to a pair of large opening curved surface parts 21, 21, the bolt 3 is pressed in the insertion hole 16 and an idle rotationstopping is performed for the bolt 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt locking structure for connecting a fastening object to a predetermined portion using a serration bolt, and is suitable for a bolt for fastening a suspension component of a four-wheeled vehicle.

[0002]

2. Description of the Related Art When a suspension rod or the like is fixed to other parts such as a suspension arm by using a general-purpose bolt, when a bolt and a nut are used in combination, both the bolt side and the nut side are turned by a spanner or the like. You have to stop. As described above, the rotation stopping work performed with a spanner or the like causes a reduction in assembly efficiency.

Conventionally, as shown in FIGS. 7 and 8, when a tension rod 2 is connected to a lower arm 1, a fastening bolt 3 is formed by knurling a male screw portion 4 on the distal end side, a head portion 5, and the like. An insertion hole 8 having an inner diameter slightly smaller than the serration portion 6 is formed in the plate-like end portion 7 of the tension rod 2, and the serration portion 6 is formed in the insertion hole 8. Is inserted, and the bolt 3 is inserted. The nut 11 screwed into the male screw portion 4 of the bolt 3 is used. The tension rod 2 is attached to the lower arm 1 supporting the tire 12 by the bolt 3 and the nut 11 screwed to the lower arm 1. Had joined. In the conventional anti-rotation structure, the insertion hole 8 of the tension rod 2 has a circular shape, and the serration portion 6 of the bolt 3 fitted into the hole is formed.
Is harder than the tension rod 2, the serrations 6 bite into the inner wall surface of the hole when pressed into the hole, and this has the effect of preventing the bolt 3 from turning.

[0004]

However, in the above-described conventional structure, when a high strength is required for the tension rod 2 having an insertion hole 8 for press-fitting the bolt 3, heat treatment such as quenching and tempering is required. Is required. Therefore, the hardness of the tension rod 2 increases, and the serration 6 of the bolt 3 does not bite into the inner periphery of the insertion hole 6 of the tension rod 2, and the serration 6 is conversely shaved, and a sufficient detent effect is obtained. When the nut 11 is tightened, the bolt 3 also runs idle.

[0005] As a countermeasure to prevent the bolt from rotating around, even if the bolt is increased in hardness to be harder than the tension rod, there is a limit because a problem such as cracking appears. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to not only prevent the bolt from rotating around, but also reduce the number of assembly steps in a factory. An object of the present invention is to provide a bolt rotation preventing structure capable of reducing the cost and cost.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for fastening a bolt using a bolt integrally having a male screw portion on the distal end side and a serration portion having a slightly larger outer diameter than the male screw portion. In the bolt detent structure for passing the bolt through an insertion hole opened in the object and fastening the object to be fastened and mounting the bolt at a predetermined position, the pair of holes having a larger radius of curvature concentrically arranged in the insertion hole. A large-diameter curved surface portion and a pair of small-diameter curved surfaces each having a smaller radius of curvature arranged symmetrically with respect to the center of curvature of the pair of large-diameter curved surfaces, and the pair of small-diameter curved surfaces are formed of the serration portion. The pair of large-diameter curved surface portions are located at positions that do not interfere with the outer peripheral surface, and the pair of large-diameter curved surface portions are formed along a circumference having a radius slightly smaller than the outer peripheral surface of the serration portion. Engage the part Characterized by press-fitting said bolt in said insertion hole.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bolt detent structure according to an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where a tension rod is connected to a lower arm using a serration bolt. FIG. 1 is a partial cross-sectional view along a center line of a tension rod of a bolt rotation preventing structure according to an embodiment of the present invention, and FIG. 2 shows a shape of an insertion hole into which a bolt is press-fitted.

In the bolt rotation preventing structure according to this embodiment, a bolt 3 similar to the conventional one is used for connecting the tension rod 2 to the lower arm 1, and the bolt 3 is opened at the plate-like end 7 of the tension rod 2. A certain insertion hole 16 has a pair of small-diameter curved surfaces 18, 18 having a smaller radius of curvature, and a pair of large-diameter curved surfaces 21, 21 arranged concentrically and having a larger radius of curvature.
The pair of small-diameter curved surface portions 18 and 18 are symmetrically arranged around the center of curvature of the pair of large-diameter curved surface portions 21 and 21.

The pair of small-diameter curved surfaces 18, 18 are located at positions where they do not interfere with the outer peripheral surface of the serration 6.
The pair of large-diameter curved surface portions 21 and 21 are formed along a circumference having a radius of curvature slightly smaller than the outer peripheral surface of the serration portion 6, and a part of the serration portion 6 is formed on the pair of large-diameter curved surface portions 21 and 21. Is pressed into the insertion hole 16 to prevent the bolt 3 from turning.

The lower arm 1 has a circular through hole 13 having a diameter slightly larger than the outer diameter of the male screw portion 4 of the bolt 3. The tension rod 2 has an insertion hole 16 formed at the position of the through hole 13 of the lower arm 1.

The bolt 3 comprises a male screw 4 on the tip side and a head 5
Has a serration portion 6 having an outer diameter slightly larger than the external thread portion 4 and smaller than the head portion 5, and a tapered portion 9 is interposed between the serration portion 6 and the external thread portion 4. . The serration portion 6 is knurled on the outer periphery, and is dimensioned so that the knurled portion fits in the insertion hole 16.

As shown in FIGS. 3 and 4, the insertion hole 16 has an inner periphery of a circular hole 20 formed concentrically except for a long hole 17 and a pair of small-diameter curved surfaces 18 at both ends of the long hole 17. It is configured by combining a surface. At a predetermined position of the tension rod 2, in FIG. 3, an elongated hole 17 in which the inner dimensions of the straight parallel portions 19, 19 are slightly smaller than the diameter of the serration portion 6 and the inner size in the longitudinal direction is not smaller than the diameter of the serration portion 6. Open by punching.

Next, as shown by a two-dot chain line in FIG. 4, a drill or reamer whose diameter is slightly smaller than the outer diameter of the serration portion 6 and larger than the outer diameter of the male screw portion 4 is concentric with the slot 17. When passed, an insertion hole 16 as shown in FIG. 2 is formed. The diameter of the circular hole 20 is the straight parallel part 1
A pair of small-diameter curved surface portions 1 larger than the inner dimension between 9 and 19
It is smaller than the inner dimension between 8,18.

[0014] Such insertion hole 16, a pair of small diameter curved face part which is opposite end portions of the elongated hole 17 having a small radius of curvature R ₁ of the curved surface than the radius of the serrations 6 of the bolt 3 18,1
8 and a pair of large diameters which are portions of the inner peripheral surface of a circular hole 20 which is formed concentrically with the elongated hole 17 with a radius R ₂ slightly smaller than the radius of the serration portion 6 and larger than the radius of the male screw portion 4. It is formed in combination with the curved surface portion 21. When the bolt 3 is press-fitted, at least a part of the pair of small-diameter curved surface portions 18 is, as shown in FIG.
The pair of large-diameter curved surface portions 21 are located at positions where they do not interfere with the serration portion 6 as shown in FIG.

In the bolt locking structure according to the embodiment of the present invention, the tension rod 2 is superimposed on the lower arm 1, and the bolt 3 is inserted straight into the through hole 13 and the insertion hole 16 with the core aligned. Insert the part 6 into the insertion hole 16
, The knurled portion of the serration portion 6 cuts into the pair of large-diameter curved surface portions 21 of the insertion hole 16, and the bolt 3 is prevented from turning. In this state, a nut similar to that shown in FIG. 8 is screwed into the male screw portion 4 and tightened to connect the tension rod 2 to the lower arm 1.

According to the bolt rotation preventing structure according to the embodiment of the present invention, the knurled portions of the serration portion 6 that oppose the pair of large-diameter curved surfaces 21 and 21 reliably remain, and the pair of small-diameter curved surfaces The knurled portion of the serration portion 6 is hooked on each inflection portion 22 at the boundary between the portions 18 and 18 and the pair of large-diameter curved surface portions 21 and 21, and the bolt 3 is reliably prevented from turning. Compared to the press-fit load of the bolt 3, the insertion hole 1
Since the required frictional force between the inner surface of the serration 6 and the outer peripheral surface of the serration 6 is small, the knurled portion of the serration 6 is not scraped. Even if you try to drill holes after applying heat treatment to the fastening object in order to obtain high strength, the surface will be hardened by the heat treatment and it will be difficult to drill holes. In general, it is necessary to perform hole finishing after the heat treatment. Even when the present invention is applied, no additional process is required for manufacturing the tension rod 2 and there is no increase in cost.

As to the effect of the present invention, specific numerical values are shown in comparison with the prior art. When the bolt 3 whose serration portion 6 has a diameter of 10.2 mm is used, the diameter of the conventional circular insertion hole 8 is 10 mm, and Insertion hole 16 (8 x 11.5 mm)
According to experimental results when the radius of curvature of the small-diameter curved surface portion 18 is 4 mm and the radius of curvature of the large-diameter curved surface portion 21 is 5 mm, the turning torque is 4 to 7 kgf-m in the prior art, whereas Was 10 kgf-m or more. As a result, in the case of the insertion hole 16 having the shape according to the present invention, the rotation torque greatly exceeds the tightening torque of the bolt of the tension rod 2 of 4 to 6 kgf-m, and the rotation prevention function is sufficiently achieved.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the present invention can be applied to a case other than the case where the tension rod 2 is connected to the lower arm 1. Instead of the combination of the oblong hole 17 and the circular hole 20, the oblong hole and the diameter are larger than the small diameter of the oblong hole. The insertion hole may be formed in combination with a small circular hole. In addition, the present invention is not limited to the above structure, and any shape may be used as long as at least one tooth of the serration of the bolt can be hooked, and as shown in FIG. 6, on the inner peripheral surface side of the insertion hole,
A pair of parallel inner peripheral surfaces are arranged in multiple pairs, and the distance from the center of the insertion hole to the inner peripheral surface is different, so that it does not interfere with the outer peripheral surface of the serration part. Even in the cross-shaped or hexagonal insertion hole 16 having a certain interference part, the effect of stopping the bolt is achieved, and the degree of engagement with the serration teeth is regular, irregular, continuous or discontinuous. It does not matter.

[0019]

According to the present invention, a pair of concentrically arranged large-diameter curved surfaces having a larger radius of curvature and a pair of the large-diameter curved surfaces having a smaller radius of curvature symmetrically arranged with the center of curvature as the center of symmetry. A pair of small-diameter curved surface portions is provided in the insertion hole, the pair of small-diameter curved surface portions are located at positions where they do not interfere with the outer peripheral surface of the serration portion, and the pair of large-diameter curved surface portions have a radius slightly smaller than the outer peripheral surface of the serration portion. It is formed along the circumference, and the serration portion is engaged with the pair of large-diameter curved surface portions and the bolt is pressed into the insertion hole, so that the serration portion is hooked on the insertion hole and the bolt is prevented from turning. When assembling an object to be fastened, it is no longer necessary to use a wrench on both the bolt and nut to prevent rotation, and even for a high-strength object that has been heat-treated, the bolt can be attached without increasing the processing cost. Surely And stopping an effect that it is possible to reduce the assembly steps. In addition, a pair of small-diameter curved surface portions located at positions that do not interfere with the outer peripheral surface of the serration portion along the arc at both ends of the elongated hole having a parallel portion having a smaller inner surface dimension than the outer diameter of the serration portion; By forming the insertion hole with a pair of large-diameter curved surfaces along a circle that is larger than the inner size of the pair and is smaller than the inner size between the pair of small-diameter curved surfaces, the insertion hole can be extremely easily formed. Further, a plurality of pairs of parallel inner peripheral surfaces are arranged on the inner peripheral surface side of the insertion hole, and the distance from the center of the insertion hole to the inner peripheral surface is different, so that it does not interfere with the outer peripheral surface of the serration portion. A non-interfering part at the position and an interfering part at the interfering position are provided, and the serration is engaged with the interfering part to press-fit the bolt into the insertion hole. The effect that man-hours can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view along a center line of a tension rod of a bolt detent structure according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a shape of an insertion hole into which a bolt is press-fitted.

FIG. 3 is an explanatory diagram of a method of opening an insertion hole according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a method of opening an insertion hole according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a main part of the bolt rotation preventing structure according to the embodiment of the present invention and crossing the tension rod at a position passing through the center of the bolt.

FIG. 6 is a view showing a modification of the shape of an insertion hole into which a bolt is press-fitted.

FIG. 7 is a schematic configuration diagram illustrating a main part of a suspension to which a bolt detent structure is applied in a conventional four-wheeled vehicle.

FIG. 8 is a partial sectional view for explaining a conventional bolt rotation preventing structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower arm 2 Tension rod 3 Bolt 6 Serration part 7 Plate end 13 Through hole 16 Insertion hole 17 Long hole 18 Small diameter curved surface part 19 Parallel part 20 Circular hole 21 Large diameter curved surface part 22 Inflection part

Claims (4)

[Claims] 1. A bolt having a male screw part on the distal end side and a serration part having a slightly larger outer diameter than the male screw part, and passing the bolt through an insertion hole formed in an object to be fastened, In the bolt detent structure for fastening an object and attaching it to a predetermined position, the insertion hole is provided with a pair of large-diameter curved surfaces having a larger radius of curvature concentrically arranged and a center of curvature of the pair of large-diameter curved surfaces. A pair of small-diameter curved surfaces having a smaller radius of curvature disposed symmetrically with respect to the center of symmetry, wherein the pair of small-diameter curved surfaces are located at positions where they do not interfere with the outer peripheral surface of the serration portion; The part is formed along the circumference of a radius slightly smaller than the outer peripheral surface of the serration part, and the serration part is engaged with the pair of large diameter curved surface parts to press-fit the bolt into the insertion hole. Bo characterized by Rotation prevention structure. 2. The bolt rotation preventing structure according to claim 1, wherein the outer peripheral surface of the serration portion is formed along an arc at both ends of a long hole having a parallel portion having a smaller inner surface dimension than the outer diameter of the serration portion. A pair of small-diameter curved surfaces located at positions that do not interfere with each other, and a pair of large-diameter curved surfaces along a circle whose diameter is larger than the inner dimension between the parallel portions and smaller than the inner dimension between the pair of small-diameter curved portions, A bolt rotation preventing structure, wherein the insertion hole is formed. 3. A bolt having a male screw portion on the distal end side and a serration portion having a slightly larger outer diameter than the male screw portion, and passing the bolt through an insertion hole formed in an object to be fastened. In a structure for preventing rotation of a bolt for fastening an object to a predetermined position, the inner peripheral surface of the insertion hole is concentrically arranged and has a different distance from the center and does not interfere with the outer peripheral surface of the serration portion. A non-interfering portion and an interfering portion at a position interfering with each other, wherein the serration portion is engaged with the interfering portion to press-fit the bolt into the insertion hole. 4. A bolt having a male screw portion on the distal end side and a serration portion having a slightly larger outer diameter than the male screw portion, and passing the bolt through an insertion hole formed in an object to be fastened. In a bolt detent structure for fastening an object to a predetermined location, a plurality of pairs of parallel inner peripheral surfaces are arranged on the inner peripheral surface side of the insertion hole, and the pair of parallel inner peripheral surfaces are arranged from the center of the insertion hole. A non-interfering portion at a position where the distance to the inner peripheral surface is different and does not interfere with the outer peripheral surface of the serration portion and an interference portion at a position to interfere with the serration portion; A bolt rotation preventing structure, wherein the bolt is press-fitted into the insertion hole.