JP4497502B2 - Mounting bolts and mounting nuts for retrofit members - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses, as a main member, a retrofitting member such as, for example, a high-tensile bolt and nut used for attaching a member in a steel structure, a mounting bolt and nut used for fastening a finger plate to a PC girder, and the like. The present invention relates to a mounting bolt and a mounting nut to be fastened and fixed.
[0002]
[Prior art]
Conventionally, as a technique for fastening and fixing a retrofitting member to a main member, for example, there is a method of fixing a finger plate (FP) to a concrete rail (PC girder) of a monorail. In this case, the PC girder corresponds to the main member and FP corresponds to the retrofitting member. The FP connects PC girders for passing the vehicle while absorbing the expansion and contraction of the PC girders themselves, and is fixed to an FP receiving seat embedded and fixed to the PC girders. Mounting bolts are used for.
[0003]
The force applied to the mounting bolt is only the tension due to the tightening force when the head part abuts uniformly on the FP as a retrofitting member, but in addition to the tension due to the tightening force when the head does not abut evenly. Bending stress is applied. And it will be in the situation where it is easy to fracture in the base end of a bolt axis part. Therefore, when tightening the mounting bolts, it is necessary to try to suppress the generation of bending stress by making the surface pressure of the contact surface with the back member of the head uniform.
[0004]
[Problems to be solved by the invention]
However, tolerances occur in the finishing accuracy of the counterbore surface of the retrofitting member and the accuracy of the screw portion for the mounting bolt formed on the main member side (FP receiving seat embedded in the PC girder in the conventional example). In the case where is a difference, even if the tightening operation is carefully performed, the contact of the mounting bolt head with the post-facing member facing face may not be uniform.
[0005]
FIG. 6 shows an example of a state in which only a specific portion of the mounting bolt head is in contact with the counterbore surface of the FP which is a retrofitting member. This mounting bolt 21 is in a state in which only a part C ′ of the head 22 is in contact with the spot facing surface 31 of the FP 30 due to the fact that its own axis X ′ is tilted and the spot facing surface 31 is irregular. ing. A tensile force P due to tightening is generated on the shaft portion 23 of the mounting bolt 21 downward in the drawing, and a tightening reaction force R is generated between the portion C ′ of the head 22 and the counterbore surface 31. Yes. The stress σ _p (= P / A: A is a cross-sectional area) due to the tensile force P is evenly distributed in the shaft section as shown in FIG. 6B, but the bending stress σ _m (= Pe due to the reaction force R). / Z: e is the distance from the axis X ′, and Z is the section modulus), as shown in FIG. 6C, is the maximum at the outer peripheral portion of the shaft portion 23 on the side where the head portion 22 contacts the counterbore surface 31. And the distribution gradually decreases as the distance from the distance increases. As shown in FIG. 6D, the stress generated in the shaft portion 23 is a combination of these σ _p and σ _m . Therefore, in the mounting bolt 21, stress concentrates only on a specific portion of the shaft portion 23, and destruction of the bolt proceeds from this stress concentration portion.
[0006]
The tensile stress σ _p and the bending stress σ _m can be expressed by a tensile force P. For example, in the case of M16 bolt (A = 2 cm ² , Z = 0.4 cm ³ , e = 1.45), σ _p = 0.5P , Σ _m = 3.62P. Then, the stress σ _p + σ _m generated at the stress concentration location is 8.24 times the value of the pure tensile stress σ _p .
[0007]
When tightening and fixing the retrofitting member to the main member, in addition to the method of using the bolt as described above, a stud is protruded from the main member and the stud is inserted into the bolt hole of the retrofitting member. A method of fastening and fixing the retrofitting member with a nut is also known. However, the same problem as described above, that is, the problem that the stud is broken due to the stress concentration has occurred even by the method of tightening and fixing with the nut.
[0008]
By the way, it is known that the contact state between the mounting bolt or mounting nut and the counterbore surface usually becomes better as time passes. That is, the contact portion of the mounting bolt or the mounting nut with the counterbore surface and the counterbore surface are worn, and the head of the mounting bolt or the mounting nut comes into contact with the counterbore surface uniformly over time. Therefore, in the initial tightening stage, even if only a specific location of the mounting bolt or mounting nut abuts against the counterbore surface and stress concentration occurs at a predetermined location on the mounting bolt or stud, In many cases, the head or the entire back surface of the mounting nut comes into contact with the counterbore surface, and stress is evenly distributed over the entire shaft section of the mounting bolt or the entire cross section of the stud.
[0009]
Therefore, the present invention provides a mounting bolt and a mounting nut for a retrofitting member that can suppress bending stress concentrated at a specific location in the initial stage of tightening and prevent damage due to stress concentration when the retrofitting member is fastened to the main member. The purpose is to do.
[0010]
[Means for Solving the Problems]
(Claim 1) A mounting bolt according to the present invention is a mounting bolt that fastens and fixes a retrofitting member having a receiving seat having a flat spot facing surface to a main member, and is attached to a hole edge of the spot facing surface. The abutting portion is a conical surface, and the conical surface has a gradient in a range of 1/15 to 1/30 with respect to the spot facing surface in a longitudinal section including its own axis.
[0011]
According to this mounting bolt, the conical surface comes into contact with the hole edge of the spot facing surface in the initial stage of tightening, and the contact surface gradually spreads away from the axis as the familiarity progresses, and comes into contact with a wide range. . Therefore, at the initial stage of tightening, bending stress is generated even if only a specific part of the conical surface comes into contact with the hole edge due to irregularities of the counterbore surface or screw part (thread groove for the mounting bolt formed on the main member side). Since the bending moment to be generated is small at a position close to the axis of the mounting bolt, the generated stress can be suppressed to a small level, and damage due to stress concentration can be prevented.
[0012]
The conical surface has a gradient in a range of 1/15 to 1/30 with respect to the counterbore surface in a longitudinal section including its own axis, so that the mounting bolt has an irregular surface of the counterbore or threaded portion. The shape corresponding to the actual tilt when tilted can be obtained. If the gradient is smaller than 1/30, the inclination angle of the mounting bolt becomes smaller, and the contact position at the initial stage of tightening may move away from the axis, and the bending stress may not be reduced. On the other hand, if the gradient is larger than 1/15, the contact area does not increase so much even if the familiarity progresses, and there is a possibility that a sufficient tightening force cannot be obtained.
[0013]
(Claim 2) A mounting nut according to the present invention is a mounting nut for fastening and fixing a retrofitting member having a receiving seat with a flat face facing the face to a main member provided with a stud. The portion of the face facing the hole edge is a conical surface, and the conical surface has a gradient in the range of 1/15 to 1/30 with respect to the face facing surface in a longitudinal section including its own axis. Have.
[0014]
According to this mounting nut, the conical surface abuts against the hole edge of the counterbore surface in the initial stage of tightening, and even when only a specific portion of the conical surface abuts against the hole edge due to irregularity of the counterbore surface or the mounting nut screw portion, Similar to the mounting bolt, the generated stress can be kept small, and damage due to stress concentration can be prevented. And, since the conical surface of the mounting nut has a gradient in a range of 1/15 to 1/30 with respect to the counterbore surface in a longitudinal section including its own axis , as in the case of the mounting bolt, A shape corresponding to the actual inclination when the mounting nut is inclined due to irregularity of the counterbore face or the mounting nut screw portion or the like can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1-4, the specific example of the attachment bolt of the retrofitting member concerning this invention is shown. FIG. 1 is a front view showing an overview of the mounting bolt. FIG. 2 is a cross-sectional view showing a process in which the mounting bolt is tightened to a stable state. FIG. 3 shows a state in which only a specific portion of the head of the mounting bolt is in contact with the spot facing surface, (a) is a sectional view, (b) is a distribution diagram of tensile stress, and (c) is a distribution of bending stress. FIG. 4D is a distribution diagram of the composite stress. FIG. 4 is a plan view showing a state in which the finger plate is fastened and fixed.
[0016]
The mounting bolt 1 is used to fasten and fix a finger plate 10 as a retrofitting member to a PC girder 15 as a main member. A bolt hole 12 is formed in the finger plate 10, and a bolt receiving seat 11 is formed in the finger plate surface side opening of the bolt hole 12. And the counterbore surface 11a of the bolt receiving seat 11 is flat. The mounting bolt 1 includes a head portion 3 and a shaft portion 4 extending from the head portion 3, and is in contact with the bolt hole edge 11 b of the spot facing surface 11 a between the head portion 3 and the shaft portion 4. The portion is a conical surface 2. Further, a thread groove (threaded portion) is formed at a position corresponding to the bolt hole 12 of the PC girder 15 so that the mounting bolt 1 inserted through the bolt hole 12 is screwed to fasten and fix the finger plate 10. It has become.
[0017]
(Claim 1) According to this mounting bolt 1, the conical surface 2 abuts against the hole edge 11b of the spot facing surface 11a as shown in FIG. 2a gradually spreads away from the axis X, and finally comes into contact with a wide range as shown in FIG. Therefore, for example, as shown in FIG. 3 (a), even when only a specific portion C of the conical surface 2 is in contact with the hole edge 11b due to irregularities of the spot facing surface 11a or the threaded portion in the initial stage of tightening, bending stress is generated. Since the bending moment to be generated is small if the position is close to the axis X of the mounting bolt 1, the generated stress can be suppressed small, and damage due to stress concentration can be prevented.
[0018]
Furthermore, the conical surface 2 has a gradient in the range of 1/15 to 1/30 with respect to the spot facing surface 11a in the longitudinal section including the axis X of the mounting bolt 1 , so that the mounting bolt 1 has the spot facing surface 11a. Or a shape corresponding to the actual inclination in the case of inclining due to irregularities in the threaded portion or the like. If the gradient is smaller than 1/30, the inclination angle of the mounting bolt 1 becomes smaller, and the contact position at the initial stage of tightening may move away from the axis, and the bending stress may not be suppressed. On the other hand, if the gradient is larger than 1/15, the contact area does not increase so much even if the familiarity progresses, and there is a possibility that a sufficient tightening force cannot be obtained.
[0019]
(Claim 2) FIG. 5 is a sectional view showing a specific example of a mounting nut of a retrofit member according to the present invention. In the following description, substantially the same parts as those in the specific example are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0020]
The mounting nut 5 is used to fasten and fix the finger plate 10 as a retrofitting member to the PC girder 15 as the main member. A stud 16 protrudes from the PC girder 15, and the finger plate 10 is fastened and fixed by a mounting nut 5 with the stud 16 inserted through the bolt hole 12. The portion of the mounting nut 5 that contacts the hole edge 11b of the spot facing surface 11a is the conical surface 2.
[0021]
According to this mounting nut 5, the conical surface 2 abuts against the hole edge 11b of the counterbore surface 11a in the initial stage of tightening, and only a specific portion D of the conical surface 2 has a hole due to irregularity of the counterbore surface 11a or the mounting nut screw portion. Even in the case of coming into contact with the edge 11b, as in the case of the mounting bolt 1, the generated stress can be suppressed to a small level, and damage due to stress concentration can be prevented.
[0022]
Further, the conical surface 2 preferably has a gradient in the range of 1/15 to 1/30 with respect to the spot facing surface 11a in a longitudinal section including the axis Y of the mounting nut 5 , and in this way, the mounting bolt Similarly to the case of 1, the shape corresponding to the actual inclination when the mounting nut 5 is inclined due to irregularity of the spot facing surface 11a or the mounting nut screw portion or the like can be obtained.
[0023]
【The invention's effect】
According to the mounting bolt according to the present invention, at the initial stage of tightening, only a specific portion of the conical surface hits the hole edge due to an irregularity of the spot facing surface or the threaded portion (screw groove for the mounting bolt formed on the main member side). even if the contact, bending stress since the smaller if located closer to the axis of the bending moment mounting bolt to generate, it is possible to reduce the stress generated, can prevent breakage due to stress concentration, the mounting bolt is countersunk It can be made into the shape corresponding to the actual inclination at the time of inclining by irregularities of a surface or a screw part.
[002 4 ]
According to the mounting nut according to the second aspect of the present invention, even when only a specific portion of the conical surface comes into contact with the hole edge due to irregularity of the counterbore surface or the mounting nut screw portion, the same occurs as the mounting bolt. Stress can be kept small, damage due to stress concentration can be prevented , and in the same way as in the case of the mounting bolt, it corresponds to the actual inclination when the mounting nut is inclined due to irregularity of the counterbore surface or mounting nut screw part, etc. It can be a shape.
[Brief description of the drawings]
FIG. 1 is a front view showing an overview of a mounting bolt according to the present invention.
FIG. 2 is a cross-sectional view showing a process in which the mounting bolt is tightened to a stable state.
FIG. 3 shows a state in which only a specific portion of the head of the mounting bolt is in contact with the spot facing surface, (a) is a sectional view, (b) is a distribution diagram of tensile stress, and (c) is a bending stress. Distribution diagram, (d) is a distribution diagram of synthetic stress.
FIG. 4 is a plan view showing a state in which the finger plate is fastened and fixed.
FIG. 5 is a cross-sectional view showing a specific example of a mounting nut according to the present invention.
FIGS. 6A and 6B show an example of a state in which only a specific portion of a conventional mounting bolt head is in contact with the counterbore surface of the FP, FIG. 6A is a sectional view, FIG. 6B is a distribution diagram of tensile stress, and FIG. Is a distribution diagram of bending stress, and (d) is a distribution diagram of synthetic stress.
[Explanation of symbols]
1 Mounting bolt 2 Conical surface 5 Nut 10 Retrofit member (finger plate)
11 receiving seat 11a spot facing surface 11b hole edge 15 main member (PC girder)
16 Stud X, Y axis

Claims (2)

A mounting bolt for tightening and fixing a rear member (10) having a receiving seat (11) having a flat spot facing surface (11a) to a main member (15), the hole of the spot facing surface (11a) The portion that contacts the edge (11b) is a conical surface (2) ,
The conical surface (2) has a gradient in a range of 1/15 to 1/30 with respect to the spot facing surface (11a) in a longitudinal section including its own axis (X). Mounting bolt (1) characterized by that. A mounting nut that fastens and fixes a rear member (10) having a receiving seat (11) with a flat facing surface (11a) to a main member (15) provided with a stud (16), The portion that contacts the hole edge (11b) of the spot facing surface (11a) is a conical surface (2) ,
The conical surface (2) has a gradient in a range of 1/15 to 1/30 with respect to the spot facing surface (11a) in a longitudinal section including its own axis (Y). Mounting nut (5) characterized by that.

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