JP2000136751A - Long bolt steadying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the stress of a steadying device for a long bolt including a tie bolt and prevent fretting corrosion fatigue at a contact between a bushing for a steadying mechanism and the long bolt. SOLUTION: In this steadying device for a long bolt which has a thinner portion 1a, smaller than the outer diameter of another larger portion 1b, at the middle, in which a two-split bushing 8 is fitted, the long bolt is formed by linking the thinner portion 1a at its ends to the larger portion 1b via a smooth curved face and the bushing 8 is provided with curved faces on the inner peripheries at its ends and tapered faces on the outer peripheries, so that the bushing 8 is fitted in contact with both curved faces and a tapered link 9 is inserted in the outer peripheries of the bushing in press contact of its tapered face with the tapered faces of the bushing 8 for fixing the bushing 8 to the long bolt via the tapered link 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a long bolt provided with a steady rest device at an intermediate portion, such as a tie bolt for a large diesel engine.

[0001]

2. Description of the Related Art FIG. 5 is a sectional view of an essential part showing an outline of a tie bolt tightening structure in a large diesel engine. FIG.
, 5 is a cylinder jacket, 6 is a frame, 7 is a base plate, and these members are fastened and fixed by a long tie bolt 1 penetrating from the upper surface of the cylinder jacket 5 to the lower surface of the base plate 7. .

Since the tie bolt 1 is long, it is excited by the vibration of the engine. Therefore, the tie bolt 1 is usually provided with an anti-sway mechanism at an intermediate portion to suppress the vibration.

FIGS. 6 and 7 show an example of a conventional anti-sway mechanism for the tie bolt 1. FIG. 6 is an enlarged view of a portion Z in FIG.
FIG. 7 is a sectional view taken along line AA of FIG. 6 and 7, the tie bolt 1 forms a body detail 1a having a small diameter at a part of an intermediate portion thereof. The torso details 1a are:
The tie bolt 1 is smoothly connected to the large diameter portion 1b by a curved surface portion 1c having a predetermined radius of curvature.

[0004] Reference numerals 2 and 2 denote bushes fitted on the outer periphery of the body detail 1a. The bushes 2 and 2 are formed in two parts and provided with relief portions 2a at both ends. The bushes 2 and 2 are fixed to the outer periphery of the body detail 1a by four fixing bolts 3 with a predetermined surface pressure. In addition, the bushes 2 and 2
As shown in FIG. 7, the outer periphery of the tie bolt 1 is fitted into the tie bolt hole 10 with a relatively firm fit so as to prevent the tie bolt 1 from moving in the lateral direction (vibration). It is pressed against the tie bolt hole 10 by the steady rest bolt 4.

[0005]

However, the conventional tie-bolt steady rest mechanism as shown in FIGS. 6 and 7 has the following problems.

That is, in the above-described conventional apparatus, the body detail 1a having a small diameter at the portion where the bushes 2 and 2 for preventing the tie bolt 1 from swinging is formed is formed. As a result, the rigidity of the tie bolt 1 is significantly reduced (for example, if (the outer diameter of the body detail 1a) / (the outer diameter of the large diameter part 1b) = 0.8), the rigidity of the body detail 1a is 0.8.
³ = 0.51, which is about 1/2 of the large diameter portion). Due to such a decrease in rigidity of the body detail 1a, there is a possibility that the tie bolt 1 may be cut off in the body detail 1a.

The portion of the tie bolt 1 near the connection with the curved surface portion 1c of the body detail 1a is a stress concentration portion of the tie bolt 1, and bushes 2 and 2 are fitted into the stress concentration portion. Fretting fatigue is likely to occur due to contact with the bushes 2 and 2. For this reason, in the above-mentioned conventional device, the stress concentration portion and the fretting fatigue occurrence portion are superimposed, and the strength of this portion tends to be significantly reduced.

Further, in the above-mentioned conventional structure, since the bushes 2 and 2 which are half are fastened to the outer periphery of the body detail 1a by a plurality of fixing bolts 3 and fixed, the bushes 2 and 2 are fixed to the body detail 1a. It is difficult to obtain a sufficiently large tightening surface pressure, and as a result, fretting fatigue occurs in the contact portion between the tie bolt 1 (the body details 1a) and the bushes 2 and 2, thereby causing a crack 12 in the tie bolt 1. Easier to do.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the stress of a mounting portion of a long bolt such as a tie bolt and a bush of a steadying mechanism. An object of the present invention is to provide a long bolt steady rest device that prevents fretting fatigue from occurring in a contact portion between the bolt and the long bolt.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and the first means, which is the gist thereof, is:
In the middle part of a long bolt such as a tie bolt of a diesel engine, a body detail with a diameter smaller than the outside diameter of the other large diameter part is provided, and a long bush is inserted by inserting a split bush into the body detail. In the steady rest device, the long bolt is formed by connecting both ends of the body detail and the large diameter portion with a smooth curved surface,
The bush has a curved surface formed on the inner periphery at both ends thereof, and a tapered surface is formed on the outer periphery, and the bush is inserted into the outer periphery of the body detail by abutting both of the curved surfaces, and On the outer periphery of the bush, a taper ring having a taper surface formed on the inner periphery is inserted by pressing the taper surface and the taper surface of the bush into pressure contact, and the bush is fixed to the long bolt by the taper ring. is there.

According to the above means, since the tapered ring is press-bonded to the outer periphery of the split bush at the tapered surface, a fixing bolt for connecting the bush unlike the conventional one is not required. The outer diameter of the body details can be increased by reducing the thickness of the bush by the bolt installation space. Therefore, the rigidity of the body details can be increased as compared with the conventional one, and the bending or tensile stress of the bolt can be reduced.

In addition, since the structure is such that the halved bush is pressed against the curved surface of the bolt by tightening the taper ring as described above, the contact surface pressure between the bush and the bolt can be increased as compared with the conventional one. Further, the contact surface pressure can be made uniform, thereby preventing the occurrence of fretting fatigue at the contact portion between the bush and the bolt.

Further, since the bush and the bolt are in contact with each other on a curved surface away from the stress concentration portion of the body detail, the contact portion, which is a site where fretting fatigue can occur, and the stress concentration portion overlap. And strength reduction due to such superimposition can be prevented.

The second means is to provide a body detail smaller in diameter than the outside diameter of the other large diameter part in the middle part of a long bolt such as a tie bolt of a diesel engine, and divide the body detail into two. In a steady rest device for a long bolt which is fitted with a bush, the long bolt connects both ends of the body detail and the large diameter portion with a smooth curved surface, and the curved surface and the large diameter portion A projection having a diameter larger than that of the body detail is provided between the projections, the inner circumferences of both ends of the bush are fitted to the outer circumference of the projection, and the divided portions of the bush are connected by a fixing bolt. .

According to the above-mentioned means, since the split bush and the bolt are pressed against each other at the large-diameter projection separated from the stress concentration portion of the bolt, the stress concentration portion and the occurrence of fretting fatigue occur. Since the contact point, which is a possible point, does not overlap and the contact part is a large-diameter, small-bending-stress outer periphery, fretting fatigue under high stress is avoided.

Further, since the split bush has a very simple structure in which a plurality of fixing bolts are pressed against the outer periphery of the projection of the bolt, and there is no fitting portion between the bolt and the bush, the steady rest device is provided. The whole processing becomes easy.

In a third aspect, in the first and second aspects, a groove is formed between the curved surface portion and the large diameter portion of the long bolt.

According to the above means, the groove provided in the vicinity of the contact portion between the bush and the bolt functions to reduce the contact stress of the contact portion, and the contact stress is reduced.

[0019]

FIG. 5 is a longitudinal sectional view of a main part showing a tightening structure of a tie bolt for a large diesel engine to which the present invention is applied. In FIG. 5, reference numeral 5 denotes a cylinder jacket;
Is a frame, and 7 is a base plate. These three members are fastened and fixed by tie bolts 1 inserted into tie bolt holes 10 penetrating from the upper surface of the cylinder jacket 5 to the lower surface of the base plate 7.

1 and 2 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main portion of a mounting portion of a tie-bolt anti-swing mechanism. FIG. 2 is an enlarged view of a main portion of a bush and a taper ring mounting portion. It is sectional drawing.

1 and 2, reference numeral 10 denotes the tie bolt hole, 1 denotes a tie bolt inserted into the tie bolt hole 10, and 1 a denotes a body detail in which a part of an intermediate portion of the tie bolt 1 is formed to have a small diameter. is there. Numerals 11 and 11 denote upper and lower grooves formed at a connection portion between the large diameter portions 1b and 1b of the tie bolt 1 and the body details 1a, respectively, and an end between the grooves 11 and 11 and the body details 1a. They are connected by smooth curved surfaces 1c, 1c.

Reference numeral 8 denotes a bush divided into two parts, and curved surfaces 8b, 8b formed on the inner periphery near both ends of the bush.
Is fitted on the outer periphery of the body detail 1a in close contact with the curved surfaces 1c, 1c of the tie bolts. In this case, the curved surfaces 8b, 8b of the bush 8 are closer to the end than the stress concentration portion 12, which is a connection portion between the outer periphery of the body diameter portion 1a of the tie bolt 1 and the curved surfaces 1c, 1c at both ends. The stress concentration portion 12 is in close contact with the curved surfaces 1c, 1c on the tie bolt 1 side.
The above-mentioned close contact portion is prevented from overlapping. Therefore, the bush 8 is mounted with a slight gap between the inner peripheral surface 8c other than the curved surface 1c and the outer peripheral surface of the body detail 1a.

The outer peripheral surface of the bush 8 is formed as a tapered surface 8a whose diameter increases from one end to the other end, and the outer peripheral surface formed of the tapered surface 8a has the same inner peripheral tapered surface. An annular tapered ring 9 having 9a is fitted. The tapered ring 9 is pressed into the outer periphery of the split bush 8 so that both tapered surfaces 8a, 9a are crimped.
The curved surfaces 8b, 8b on the inner periphery at both ends of the tie bolt 1 and the curved surfaces 1c, 1c on the outer periphery of the tie bolt 1 are crimped and fixed to the tie bolt 1.

The outer diameter of the minimum diameter of the taper 8a of the bush 8 and the taper surface 9a of the taper ring 9 is formed to be slightly larger than the outer diameter of the large diameter portion 1b of the tie rod 1.
The taper ring 9 can be inserted into the tie rod 1. The outer surface of the taper ring is formed as a smooth straight surface, that is, a cylindrical surface, and the taper ring 9 is provided with a tie bolt hole 10 in a form in which the bush 8 is fitted on the inner periphery.
They are securely fitted without any gaps inside.

During operation of the diesel engine having the tie bolts and the anti-vibration mechanism configured as described above, a split bush 8 is attached to the outer periphery of the body detail 1a provided at the intermediate portion of the tie bolts 1. Since the outer surface 9b of the tapered ring 9 was fitted without any gap in the tie bolt hole 10, the tie bolt 1 was fixed by tightening the fitted taper ring 9 on the tapered surface.
The anti-vibration mechanism including the taper ring 9 reliably prevents vibration from occurring in the intermediate portion thereof, thereby preventing the occurrence of cutout.

In this embodiment, the cylindrical 2
Since the tapered ring 9 is crimped to the outer periphery of the split bush 8 by fitting to the tapered surface, a fixing bolt 3 for assembling the split bush like the conventional one shown in FIGS. Without using the bolt 3
It is not necessary to increase the thickness of the bush in order to provide the bush 8, and the bush 8 is thinner than the above-described conventional one, and the outer diameter of the body detail 1a can be increased accordingly. As a result, the rigidity of the body detail 1a is increased as compared with the conventional one, and the tensile or bending stress of the tie bolt 1 is reduced.

Also, the tapered ring 9 allows the tapered surface 9 provided on the inner surface thereof and the outer surface of the split bush 8 to be provided.
Since the bush 8 is configured to be pressed against the outer periphery of the tie bolt 1 by the curved surfaces 8b and 1c by pressing the a and 8a, the contact surface pressure between the bush 8 and the tie bolt 1 is increased. The tie bolts 1 are fixed to the tie bolt 1 with a high surface pressure and a uniform surface pressure, thereby preventing the occurrence of fretting fatigue.

The inner surface of the bush 8 and the outer surface of the tie bolt 1 correspond to the stress concentration portion 12a of the tie bolt body detail 1a.
The contact portions where the fretting fatigue is likely to occur do not overlap with the stress concentration portion 12 because the curved portions 8b and 1c are in contact with each other, so that a reduction in strength due to such overlap is prevented. You.

Further, since the grooves 11, 11 are provided between the body detail 1a and the large diameter portion 1b, the grooves 11, 11 are provided.
Functions to release the stress caused by the contact between the bush 8 and the curved surfaces 8b and 1c of the tie bolt 1, and the contact stress at the contact portion is reduced.

3 and 4 show a second embodiment of the present invention. FIG. 3 is a view corresponding to FIG. 1, and FIG. 4 is a view corresponding to FIG. 3 and 4, the details 1 of the body of the tie bolt 1 are shown.
a and the large-diameter portion 1b, grooves 11, 11 are engraved, and the inside of the grooves 11, 11, that is,
On the side a, projections 14 having substantially the same diameter as the large diameter portion 1b are formed with a constant width. Then, the protrusion 1
4, 14 and the body detail 1a are connected by a smooth curved surface 1c such as an arc surface.

Numeral 13 denotes a bush divided into two parts. The two bushes are connected by four (only a plurality of bushing) stop bolts 3. Bush 1 above
3 is formed with annular fitting portions 13c, 13c at both ends of the inner periphery, and the fitting portions 13c, 13c are connected to the protrusions 14, 1;
4 and is fixed to the tie bolt 1 by tightening four fixing bolts 3.

The inner peripheral surface of the bush 13 has a straight surface (cylindrical surface) 13d formed parallel to the outer peripheral surface of the body detail 1a with a predetermined gap, and both ends of the straight surface 13d. The tie bolt 1 has curved surfaces 1c, 1c and curved surfaces 13b, 13b formed with a predetermined gap.
The outer peripheral surface 13a of the bush 13 is formed in a straight surface (cylindrical surface). As shown in FIG. 3, after the bush 13 is fitted to the tie bolt 1, it is fitted to the tie bolt hole 10 without any gap. It has become.

In the second embodiment, the bush 1
Reference numeral 3 denotes a projection 1 having substantially the same diameter as the large diameter portion 1b of the tie bolt 1.
Since the tie bolts 1 and 4 are pressed into contact with each other, the bush 13 and the tie bolts 1 are separated from the stress concentration portion 12a of the tie bolt 1 at a large diameter and a small bending stress. The occurrence of fretting fatigue in the lower part is suppressed.

The contact stress acting on the contact between the fitting portion 13c of the bush 3 and the projection 14 of the tie bolt 1 is as follows:
Since the grooves 11, 11 are formed, the grooves 11, 11
11 to reduce the stress.

Also, in this embodiment, the bush 13 is divided into four tie bolts
And a tie bolt 1 and a bush 1
Since there is no fitting portion between the anti-sway mechanism 3 and the support member 3, the entire anti-sway mechanism can be easily processed.

It should be noted that the present invention is not limited to the tie bolts according to the above-described embodiment, but may be inserted through through holes inside a plurality of members.
The present invention can be applied to a long bolt for fastening these members.

[0037]

The present invention is configured as described above.
According to the first aspect of the present invention, the bush is pressed against the curved surface of the bolt by pressing the tapered ring on the outer periphery of the split bush with the tapered surface, so that the conventional fixing bolt for connecting the bush is used. This can reduce the thickness of the bush, increase the outside diameter of the body of the bolt, increase the rigidity, and reduce the bending or tensile stress of the bolt compared to the conventional one. it can.

Further, since the bush is pressed against the bolt by the tapering as described above, the contact surface pressure between the bush and the bolt can be increased and the contact surface pressure can be made uniform as compared with the conventional one. Fretting fatigue at a contact portion between the bush and the bolt can be prevented from occurring.

Since the bush and the bolt are in contact with each other on a curved surface away from the stress concentration portion of the body detail, the contact portion, which is a site where fretting fatigue can occur, and the stress concentration portion overlap. And strength reduction due to such superimposition can be prevented.

According to the second aspect of the present invention, the halved bush and the bolt are pressed against each other by a large-diameter projection separated from the stress concentration portion of the bolt, and the contact portion between the bush and the bolt is formed. Since the outer periphery of the projection has a small diameter and a large diameter, the occurrence of fretting fatigue under high stress can be avoided.

Further, the anti-sway device has a very simple structure in which the split bush is pressed against the outer periphery of the projection of the bolt with a plurality of fixing bolts, and there is no fitting portion between the bolt and the bush. The whole processing becomes easy.

According to the third aspect of the present invention, the groove provided in the vicinity of the contact portion between the bush and the bolt functions to reduce the contact stress of the contact portion, and the contact stress can be reduced. .

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a mounting portion of a tie bolt for a diesel engine according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a bush and a tapered ring mounting portion in the first embodiment.

FIG. 3 is a view corresponding to FIG. 1, showing a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a bush mounting portion in the second embodiment.

FIG. 5 is a vertical sectional view of a main part showing a tightening structure of a tie bolt for a diesel engine.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is a sectional view taken along the line AA of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tie bolt 1a Body detail 1b Large diameter part 1c Curved surface (Tie bolt) 3 Fixing bolt 5 Cylinder jacket 6 Frame 7 Base plate 8 Bush 8a Tapered surface (Bush) 8b Curved surface (Bush) 9 Tapered ring 9a Tapered surface (Tapered) 9b Outer surface (Tapering) 10 Tie bolt hole 11 Groove 13 Bush 13c Fitting part (Bushing) 14 Projection

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[Procedure amendment]

[Submission date] February 12, 1999 (1999.2.1
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

According to the above means, the groove provided in the vicinity of the contact portion between the bush and the bolt functions to alleviate the stress of the contact portion , and the stress is reduced.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

Further, since the grooves 11, 11 are provided between the body detail 1a and the large diameter portion 1b, the grooves 11, 11 are provided.
There serve to release the stress due to the curved surface 8b, 1c contact with the bush 8 and the tie bolts 1, stress <br/> of the contact portion is reduced.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

The stress acting on the contact portion between the fitting portion 13c of the bush 3 and the projection 14 of the tie bolt 1 is limited by the formation of the grooves 11,11.
Is reduced by the stress release action of

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction contents]

Further, according to the third aspect of the present invention, the groove provided near the contact portion between the bush and the bolt is provided in the contact portion .
It fulfills the function of relieving stress and can reduce the stress .

Claims (3)

[Claims] 1. An intermediate portion of a long bolt such as a tie bolt of a diesel engine is provided with a body detail smaller in diameter than the outer diameter of the other large diameter portion, and a split bush is inserted into the body detail. In the long bolt steady rest device, the long bolt is formed by connecting both ends of the body detail and the large-diameter portion with a smooth curved surface, and the bush has a curved surface on the inner periphery at both ends. While being formed, a tapered surface is formed on the outer periphery,
The bush is inserted into the outer periphery of the body detail with the two curved surfaces in contact with each other, and on the outer periphery of the bush,
A tapered ring having a tapered surface formed on an inner periphery thereof, wherein the tapered surface and the tapered surface of the bush are pressed into contact with each other, and the bush is fixed to a long bolt by the tapered ring. Bolt steady rest device. 2. An intermediate portion of a long bolt such as a tie bolt of a diesel engine is provided with a body detail smaller in diameter than the outside diameter of the other large diameter portion, and a split bush is inserted into the body detail. In the above-mentioned steady bolt stabilizing device, the long bolt couples both ends of the body detail and the large-diameter portion with a smooth curved surface, and further includes the cylinder between the curved surface and the large-diameter portion. A long bolt having a projection with a diameter larger than the details, wherein the inner circumference of both ends of the bush is fitted on the outer circumference of the projection, and the divided part of the bush is connected with a fixing bolt. Steady rest device. 3. The steady stop device for a long bolt according to claim 1, wherein a groove is formed between the curved surface portion and the large diameter portion of the long bolt.