JPS63190918A - Bolt and re-clamping method of friction grip joint member using said bolt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] A. Purpose of the Invention (Field of Industrial Application) This invention utilizes a bolt and an embedded nut that maintain a constant tightening pressure on a member to be joined between nuts screwed on both ends. A re-tightening method using this bolt for re-tightening the friction joint member will now be described.

(Prior art) Shear bolts used to maintain constant tightening pressure have a bolt head formed at one end of the shaft and a chip formed at the outer end of the threaded part at the other end. A predetermined axial force is applied to the bolt when the bolt is cut.

Additionally, friction-welded high-strength bolts are used in on-site joints of steel girders, but there have been cases of them breaking due to delayed fracture and falling. Conventional repairs have only been carried out on the web and lower flange, and repairs on the upper flange have been difficult because the nuts are buried in concrete and there is no reliable repair method for tightening the bolts using these nuts. , it was not done.

(Problems to be Solved by the Invention) In the case of a shear bolt with a bolt head, it is necessary to insert it into the bolt insertion hole of the friction joining member from the tip side. Therefore, if the extension space of the bolt insertion hole is an open space but the length on the axis is not larger than the dimension between the bolt head and the outer end of the tip, the bolt cannot be inserted into the bolt insertion hole from this extension space side. , it becomes impossible to tighten with a shear wrench, and its characteristics cannot be demonstrated. Also, when one end of the bolt insertion hole opens into a blind space and works with a nut placed in the blind space to tighten the friction bonding member,
Since the chip ends up in the blind space, its characteristics cannot be utilized.

Repairs to the upper flanges of bridges, etc. have not been carried out to date because there is no suitable re-tightening method. In reality, there are many bridges across the country with bolts still falling, and resolving this issue is an important issue for safety measures.

Structure of the Invention (Means for Solving the Problems) The present invention includes a rod-shaped main body having threads formed at both ends thereof, and an outer end of the thread at one end thereof being screwed onto the thread at one end coaxially with the main body. The present invention is characterized in that a tip is provided which has an outer diameter smaller than the inner diameter of the nut and is cut with a predetermined tightening force.

In addition, the invention of the re-tightening method provides a structure in which the joints of external wall plates of structures such as bridges are friction-bonded using bolts and nuts with nuts buried in the structure and bolt heads exposed. After removing, form a screw at both ends of the rod-shaped body in the bolt insertion hole, and attach a nut with an inner diameter smaller than the inner diameter of the nut to be screwed into the screw at one end coaxially with this body at the outer end of the screw at one end. A bolt with an outer diameter and a tip that can be cut with a predetermined tightening force is inserted from the other end, the screw at the other end is screwed into the nut, and then another screw is inserted into the screw at one end of the bolt. A nut is screwed together and the nut is tightened with a shear wrench using the tip as a support part, and the tightening force of both nuts at the time of cutting the tip is used to re-tighten the joint of the outer wall board of the structure, etc. It is characterized by

(Function) The bolt is inserted into the bolt insertion hole of the friction joining member from the threaded end on the opposite side of the chip, and the nut is screwed into the thread at this end. Then, screw another nut onto the screw on the chip side. When the inner socket of a mechanical wrench is fitted to the tip, the outer socket is fitted to this other nut, and the tip receives the reaction force of the nut's tightening force and the nut is screwed in, a predetermined axial force is introduced into the bolt. The chip will break at this point. As a result, the friction joining member is tightened with a predetermined tightening force.

In the re-tightening method, the bolt in the concrete is removed, and then the bolt according to the present invention is inserted from the side without the chip and screwed into the fixed nut in the concrete. Next, thread another nut onto the thread on the tipped end of that bolt. Now, tighten this other nut using a shear wrench that uses the tip as a support.
The joining member is re-tightened using the tightening force of both nuts when cutting the chip.

(Example) In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, reference numeral 1 denotes a rod-shaped main body, which has the same shaft diameter as a normal bolt used in various joints. Screws 2 and 3 are formed at both ends of the main body 10, and a tip 4 is provided at the outer end of the screw 3 at one end. The tip 4 is located on the same axis as the main body 1, has an outer diameter smaller than the inner diameter of the nut screwed into the screw 3, and is designed to cut with a predetermined tightening force. The cutting tightening force is appropriately determined based on the set tightening force of each joint.

The screws 2 and 3 may be oriented forward or backward relative to each other. In addition, the tip 4 has a spline, a flat surface, or other resistance on its outer circumferential surface so that even if the inner socket of the wrench receives a reaction force from the nut tightening force of the wrench, it will not slip in the rotational direction relative to this socket. Form the surface.

Figure 2 shows how to use this bolt.

Bolt insertion holes 13 and 14 of friction joining members 11 and 12
The main body 1 is inserted into the body 1, and the nut 15 is screwed onto the screw 2. Then, screw another nut 16 onto the screw 3 on the opposite side. If the extension space of the insertion hole 13 or 14 is narrow or blind, the tip 4 is inserted from the end of the screw 2 on the opposite side. After that, insert the inner socket 18 of the mechanical wrench 17 into the tip 4.
and then fit the outer socket 19 onto the bolt 16 and tighten it. The reaction force of this tightening force is the tip 4
When a predetermined axial force is introduced into the main body 1, the tip 4 breaks and the members 11 and 12 are tightened in a predetermined manner between the nuts 15 and 16.

The retightening method is as follows.

First, from the unreplaced state shown in Fig. 3, replace the bolt 21.
are removed from the concrete structure 22, brought into the state shown in FIG.
and clean 29.

Then, lubricating oil is put into the threaded portion of the nut 30 that is fixed within the structure 22.

Next, as shown in FIG. 5, the main body 1 of the bolt according to the present invention is inserted into the insertion holes 27, 28 and 29 with the screw 2 without the tip 4 facing upward, and the screw 2 is screwed into the nut. 30 years old to some extent.

In this state, as shown in FIGS. 6(a) to 6(d), screw the nut 31 into the screw 3 at the lower end of the main body 1, and use the shear wrench with the tip 4 as a support, as in the case of the bolt described above. 17, tighten the nut 31. When the tightening force of the joining members 24, 25 and 26 by both nuts 30 and 31 reaches a required value, the tip 4 breaks and re-tightening is completed with the required tightening force.

Thereafter, by repeating the same operation, all the bolts to be replaced are re-tightened with the required tightening force.

(Effects of the Invention) According to the invention of the present bolt, the extension space of the bolt insertion hole of the friction joining member is too narrow to insert the bolt into this insertion hole, or the space is blind but has a fixed nut. Even in cases where the tip does not have a tip, insert it into this insertion hole from the side without the tip, screw each nut into the screws at both ends, and while holding this tip with a shear wrench, use this tip to cut the nut on this tip side. If the bolt is tightened to a certain level, a constant axial force can always be applied to the bolt, and the joining member can be tightened between both nuts with a predetermined tightening force.

According to the invention of the re-tightening method of the present application, by using the bolt according to the present invention, the embedded nut can be reused for tightening the joining member, and the tightening force can always be kept uniform.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of the bolt according to the present invention, FIG. 2 is a side view of the bolt in use, and FIG. Figure 3 shows the uninstalled state, Figure 4 shows the bolt removed, and Figure 5 shows the bolt according to the present invention screwed into the remaining nut.
FIGS. 6(a) to 6(d) are diagrams showing the state in which the nut on the tip side of the bolt is tightened with a shear wrench, and FIG. 7 is a diagram showing the completed state of re-tightening. 1. Body, 2. Screw, 3. Screw, 4. Chip.
11...Joining member, 12...Joining member, 13...Bolt insertion hole, 14...Bolt insertion hole, 15...Nut, 16
・・Nut, 17・・Shear wrench, 18・・Kist inner socket, 19・・Outer socket, 21・・Bolt to be replaced, 22φ・・Concrete structure, 23・・・Hole,
24...Friction bonding member, 25...Friction bonding member, 26...
- Friction bonding member, 27... Bolt insertion hole, 28... Bolt insertion hole, 29... Bolt insertion hole, 30... Nut, 3
1. Natsuto. Figure 3 Figure 6 (a) (b) (C)
(d) Figure 7 η

Claims (2)

[Claims] (1) Threads are formed at both ends of a rod-shaped body, and the outer end of the screw at one end has an outer diameter smaller than the inner diameter of a nut that is coaxial with the body and is screwed into the screw at one end, and has a predetermined outer diameter. A bolt characterized by having a tip that is cut by tightening force. (2) In a structure in which the joints of external wall panels, etc. of structures such as bridges are friction-bonded using bolts and nuts with nuts buried inside the structure and bolt heads exposed, after removing the bolts, Threads are formed in the bolt insertion holes at both ends of the rod-like body, and the outer end of the screw at one end has an outer diameter smaller than the inner diameter of a nut that is coaxial with the body and is screwed into the screw at one end. A bolt equipped with a tip that can be cut with a predetermined tightening force is inserted from the other end, the screw at the other end is screwed into the nut, and then another nut is screwed into the screw at one end of the bolt. The friction welding is characterized in that the nut is tightened by a shear wrench that uses the tip as a support part, and the tightening force of both nuts when cutting the tip is used to re-tighten the joint of the outer wall board of the structure, etc. How to retighten parts.