JPH0972097A - Crack stopping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit crack propagation effectively by boring a tapered threaded hole in the foremost part of an eventually initiated crack in a structural member, and threadedly engaging a taper screw in this threaded hole. SOLUTION: A tapered threaded hole 4 is bored in the foremost part of an eventually initiated crack 3 in a structural member 2, and a taper screw 1 is threadably engaged with the hole. Because of the taper, a compressive force is given to the threaded hole part of the structural member 2 by the taper screw 1, and by its reaction, the screw 1 is put in pressure attachment to the hole 4. In the actual case where a fatigue crack 3 is initiated in a stress concentrated part such as welds followed by propagation, a through hole is penetrated by a drill in the foremost part of the crack 3 to relieve stress concentration due to cracking, and female threads are cut on the bore of this through hole so that a tapered threaded hole 4 as described is formed. Taper screw 1 is threadably engaged with the hole 4 and fixed, and thus recurrence of crack initiation is inhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crack stopping method for stopping a crack generated in a machine or building structure member.

[0002]

2. Description of the Related Art FIGS. 10A and 10B are explanatory views of a crack stopping method according to a prior art, wherein FIG. 10A is a plan view and FIG. 10B is a sectional view taken along the line DD of FIG.

As shown in FIG. 1, when a fatigue crack 3 is generated and propagates in a structural member (steel plate or the like) of a building or a mechanical structure such as a bridge or a ship, stress concentration at the tip of the crack is relaxed and the crack 3 is generated.
To prevent the expansion of the
The method of emptying 2 is taken. At that time, in order to further alleviate the stress concentration on the through hole portion, a treatment of hammering the tapered pin 31 into the through hole 32 may be performed.

If the taper pin 31 is not provided, the force flowing through the structural member bypasses the through hole portion, stress concentrates around the through hole 32, and fatigue cracks are likely to occur again. However, when the taper pin 31 is press-fitted, a force flows through the taper pin 31, so that stress concentration around the through hole is relieved and cracks are less likely to occur again. It has also been confirmed that the press-fitting of the taper pin 31 hardens the inside of the through hole 32 to improve fatigue strength.

[0005]

However, in the conventional crack stopping method as described above, since the taper pin 31 is hammered in with a hammer, the amount of press-fitting of the pin differs depending on the operator, and it is difficult to quantitatively control the effect.

When the tapping of the taper pin 31 is weak, the strength increase due to the pin press-fitting is small, and the taper pin 31 is easily removed due to the vibration of the structural member in use. On the other hand, when the tapping of the taper pin 31 is too strong, the periphery of the through hole 32 is significantly plastically deformed and a crack is generated.

Further, there is a possibility that the taper pin 31 may be slanted.

Therefore, in view of the above-mentioned prior art, it is an object of the present invention to provide a crack stopping method capable of effectively suppressing the progress of cracks generated in a structural member and quantitatively managing the amount of press fit into the structural member. To do.

[0009]

Means for Solving the Problems A first method for solving the above problems is described below.
The invention of (1) is characterized in that a taper screw hole is bored at a tip portion of a crack generated in a structural member, and a taper screw is screwed into the taper screw hole.

According to a second aspect of the present invention, a through hole is formed at the tip of a crack generated in a structural member, a ring divided in the circumferential direction is fitted into the through hole, and a screw is provided on the inner circumference of the ring. It is characterized in that a taper screw is screwed into the provided taper screw hole.

Therefore, according to the first aspect of the present invention, when the taper screw is screwed into the taper screw hole, the taper screw is fixed to the taper screw hole because these taper.
By controlling the tightening torque of the taper screw, the press-fitting amount of the taper screw can be quantitatively controlled.

Further, according to the second aspect of the invention, when the taper screw is screwed into the taper screw hole screwed in the inner circumference of the ring, since these are tapered, the taper screw pushes the ring outward. A force acts in the direction, and the ring presses the inside of the through hole. By controlling the tightening torque of the taper screw, the force with which the ring presses the inside of the through hole can also be quantitatively controlled.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 is an explanatory view of a crack stopping method according to a first embodiment of the present invention ((a) shows a plane,
(B) is a cross-sectional view taken along the line AA of (a)), FIG. 2 is an explanatory view showing directions of forces acting on the structural member, and FIG. 3 is a crack according to the first embodiment of the present invention. It is explanatory drawing which shows the enforcement procedure based on a stop method.

As shown in FIG. 1, a taper screw 1 is screwed into a taper screw hole 4 formed at the tip of a crack 3 generated in a structural member 2.

In this way, the taper screw 1 is attached to the taper screw hole 4
When they are screwed together, they are tapered, so
The taper screw 1 is fixed in the taper screw hole 4 by the force indicated by the arrow therein. That is, the taper screw hole portion of the structural member 2 receives a compressive force by the taper screw 1, and the taper screw 1 is pressed against the taper screw hole 4 by its reaction.

The construction procedure will be described with reference to FIG. When a fatigue crack 3 is generated and propagates in a stress concentration portion 5 such as a welded portion (FIG. 3 (a)), a through hole is formed at the tip of the crack 3 by a drill to reduce the stress concentration due to the crack and the penetration. A female screw is cut in the hole to form a taper screw hole 4, and a taper screw 1 is prepared (FIG. 3 (b)). Then, the taper screw 1 is screwed and fixed in the taper screw hole 4 (see FIG. 3).
(C)).

Therefore, according to the crack stopping method of the first embodiment, the force flowing in the vicinity of the taper screw hole 4 is also transmitted to the taper screw 1, so that the stress concentration around the taper screw hole is alleviated and the crack Regeneration is suppressed.

Moreover, by controlling the tightening torque of the taper screw 1, the amount of press-fitting of the taper screw 1 can be quantitatively controlled, and the taper screw 1 may fall out due to the vibration of the structural member in use, or the taper screw hole There is no risk of causing plastic deformation of the surroundings and causing cracks.

Further, since the taper screw 1 is screwed into the taper screw hole 4, there is no possibility that the taper screw 1 is press-fitted obliquely.

<Second Embodiment> FIG. 4 is an explanatory view of a crack stopping method according to a second embodiment of the present invention ((a) shows a plane,
(B) shows a cross section taken along the line BB of (a), and (c) shows a direction of arrow D of (b)), and FIG. 5 shows directions of forces acting on the structural members, etc. FIG.

As shown in FIG. 4, a ring 12 divided in the circumferential direction is fitted into a through hole 13 formed at the tip of the crack 3 generated in the structural member 2, and the inner circumference of the ring 12 is fitted. A taper screw 11 is screwed into a taper screw hole that is screwed in.

When the taper screw 11 is screwed into the ring 12 and tightened in this way, since they are tapered, the split ring 12 is pushed outward by the taper screw 11 to widen the mutual distance and form the through hole 13. Apply pressure from inside. The moving direction of the taper screw 11 and the ring 12 and the direction of the force acting on the structural member 2 at this time are as shown by the arrows in FIG.

The enforcement procedure will be described with reference to FIG. When a fatigue crack 3 is generated and propagates from a stress concentration portion 5 such as a welded portion (FIG. 6A), a through hole 13 is drilled at the tip of the crack 3 to reduce stress concentration due to the crack, and A taper screw 11 and a split ring 12 are prepared (FIG. 6 (b)). Then, the split ring 12 is fitted into the through hole 13 (FIG. 6C), and the taper screw 11 is screwed and fixed in the taper screw hole screwed on the inner circumference of the ring 12 (FIG. 6 ( d)).

Therefore, according to the crack stopping method of the second embodiment, the force flowing in the vicinity of the through hole 13 is also transmitted to the taper screw 11, so that the stress concentration around the through hole is relieved and the crack is regenerated. Suppressed.

Moreover, by controlling the tightening torque of the taper screw 11, the crimping force of the ring 12 can be controlled, and the taper screw 1 can be controlled by the vibration of the structural member in use.
There is no possibility that the 1 may fall out or the surroundings of the through hole may be plastically deformed to cause cracks.

Further, since the taper screw 11 is screwed into the ring 12, there is no fear that the taper screw 11 is press-fitted at an angle.

<Third Embodiment> FIGS. 7A and 7B are explanatory views of a crack stopping method according to a third embodiment of the present invention. 8A is a cross-sectional view taken along line CC of FIG. 8A), FIG. 8 is an explanatory view showing directions of forces acting on the structural member, and FIG. It is explanatory drawing which shows a procedure.

As shown in FIG. 7, a taper pin 21 having a threaded portion at the small-diameter side end is inserted into a through hole 23 formed at the tip of the crack 3 generated in the structural member 2 and protrudes from the structural member 2. A nut 22 is screwed onto the threaded portion.

When the nut 22 is screwed into the threaded portion of the taper pin 21 in this way, the nut 22 pulls the taper pin 21 toward the nut 22 side and the taper pin 21 bites into the through hole 23. As a result, the through hole of the structural member 2 receives a compressive force by the taper pin 21, and the reaction thereof causes the taper pin 21 to be crimped to the through hole 23. The direction of the force acting on the taper pin 21 and the nut 22 and the direction of the force acting on the structural member 2 at this time are as shown in FIG.

The construction procedure will be described with reference to FIG. When a fatigue crack 3 is generated and propagates in the stress concentration portion 5 such as a welded portion (FIG. 9A), a through hole 23 is drilled at the tip of the crack 3.
The taper pin 21 and the nut 22 are prepared while the stress concentration due to the cracks is relaxed (FIG. 9B).
Then, the taper pin 21 is inserted into the through hole 23 and the threaded portion thereof is projected from the structural member 2 (FIG. 9C). Then, the nut 22 is screwed into the screw portion and tightened (FIG. 9 (d)).

Therefore, according to the crack stopping method of the third embodiment, the force flowing in the vicinity of the through hole 23 is also transmitted to the taper pin 21, so that the stress concentration around the through hole is relieved and the reoccurrence of crack is suppressed. To be done.

Moreover, by controlling the tightening torque of the nut 22, the amount of press-fitting of the taper pin 21 can be quantitatively controlled, and the taper pin 21 may fall out due to the vibration of the structural member in use, or the circumference of the through hole may be significantly marked. There is no risk of cracking due to plastic deformation.

Further, the nut 2 is attached to the threaded portion of the taper pin 21.
Since the taper pin 21 is pulled by screwing 2 together, there is no risk of press-fitting the taper pin 21 at an angle.

[0035]

As described above in detail with the embodiments of the present invention, according to the present invention, it is possible to effectively suppress the development of fatigue cracks that have occurred in structural members, and moreover, to press fit the taper screw. Therefore, there is no risk that the taper screw will fall out due to the vibration of the structural member in use, or that the structural member will be significantly plastically deformed and a crack will be generated.

[Brief description of drawings]

FIG. 1 is an explanatory view of a crack stopping method according to a first embodiment of the present invention, in which (a) shows a plane and (b) shows (a).
The AA line arrow cross section of is shown.

FIG. 2 is an explanatory diagram showing directions of forces acting on a structural member.

FIG. 3 is an explanatory diagram showing an enforcement procedure based on the crack stopping method according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a crack stopping method according to a second embodiment of the present invention, in which (a) shows a plane and (b) shows (a).
2B is a cross-sectional view taken along the line BB of FIG.

FIG. 5 is an explanatory diagram showing directions of forces acting on the structural member.

FIG. 6 is an explanatory view showing an enforcement procedure based on the crack stopping method according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a crack stopping method according to a third embodiment of the present invention, in which (a) shows a plane (viewed in the E direction of (b)) and (b) shows (a). The CC line cross section of FIG.

FIG. 8 is an explanatory diagram showing directions of forces acting on the structural members.

FIG. 9 is an explanatory view showing an enforcement procedure based on the crack stopping method according to the third embodiment of the present invention.

FIG. 10 is an explanatory view of a crack stopping method according to a conventional technique, in which (a) shows a plane and (b) shows DD of (a).
A cross section taken along a line arrow is shown.

[Explanation of symbols]

 1 taper screw 2 structural member 3 fatigue crack 4 taper screw hole 11 taper screw 12 split ring 13 through hole 21 taper pin 22 nut 23 through hole

Claims (2)

[Claims] 1. A method of stopping cracks, characterized in that a tapered screw hole is bored at the tip of a crack generated in a structural member, and a taper screw is screwed into the tapered screw hole. 2. A taper screw formed by drilling a through hole at the tip of a crack generated in a structural member, fitting a ring divided in the circumferential direction into the through hole, and screwing the ring on the inner circumference of the ring. A crack stopping method characterized by screwing a taper screw into a hole.