JPH0137606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for tightening anchor bolts to increase the degree of fixation of steel structures, mechanical devices, etc. to foundation surfaces.

It is common for various structures and devices to be anchored to the foundation using anchor bolts, but the purpose of anchoring buildings is to prevent them from falling over and to transfer the stress of the columns from the anchor bolts and base plate to the foundation. Because of this, a high degree of fixation is required. As one method of strengthening this degree of fixation, a method of introducing axial force into the anchor bolt is often used.

Conventional methods for introducing axial force into anchor bolts include the torque control method and the nut rotation method. The torque control method uses a torque wrench to apply tightening torque to the bolt and reads the introduced axial force, while the nut rotation method divides nut tightening into two stages: preliminary tightening and final tightening. The method is to tighten the nut sufficiently with an arm wrench for pre-tightening, and rotate the nut approximately 30 degrees from the fully tightened state.

However, these axial force introduction methods have the disadvantage that it is impossible to inspect from the outside whether a predetermined axial force has been introduced or whether the nut has been reliably tightened.

The present invention solves the conventional drawbacks of the above-mentioned tightening and fixing methods for introducing axial force into anchor bolts, and provides a novel method that allows axial force to be introduced into anchor bolts reliably and easily, and which can be inspected and confirmed. This invention attempts to provide a method for tightening anchor bolts.

Embodiments of the present invention will be described below with reference to the drawings.

The shape of the anchor bolt body applied in the present invention is not particularly limited, and may be a general foundation bolt. The nut used for tightening is a special nut having a nut part 1a that is screwed into the anchor bolt, and a large diameter coupler part 1b that is loosely fitted into the anchor bolt, as shown in FIG. A grip nut 1 of the shape is used. Note that the coupler portion 1b is not provided with a screw.

In the present invention, first, the grip nut 1
Temporary tightening is performed. The anchor bolts 2 are installed on the foundation concrete 3 to protrude a required length, and the pace plate 4 is inserted onto the foundation concrete 3 through the anchor hole 5 of the base plate 4 fixed to the lower end of a column base etc. Place it on. And a washer 6 with a large area
2, screw the grip nut 1 onto the anchor bolt 2 with the coupler portion 1b facing the washer (lower side), and temporarily tighten as shown in FIG.

Next, as shown in FIG. 3, a die 7 is set on the upper part of the grip nut 1, and a die cover 8 is loosely fitted on the outside of the die 7. Then, a reaction nut 9 is connected to the anchor bolt 2 protruding upward from the die 7, a center hole jack 10 is inserted between the reaction nut 9 and the washer 6, and the reaction nut is tightened. Fix it.
In this case, since the anchor bolt 2 normally does not protrude long enough to insert the center hole jack 10, when connecting the reaction force nut 9, the anchor bolt 2 should be connected as shown in FIG. A reaction bolt 11 with an external thread 11a provided at the upper end of the
, and then the reaction nut 9 is screwed onto the reaction bolt 11.

In this way, preparations for introducing axial force into the anchor bolt 2 are completed, and then hydraulic pressure is applied to the center hole jack 10 to extend it. As a result, center hole jack 10
The anchor bolt 2 is used as a reaction force via the reaction nut 9 to push the die 7 downward.
Then, by pressing down the die 7, the large diameter coupler portion 1b of the grip nut 1 is squeezed by the die 7, and is pressed into the outer circumference of the thread of the anchor bolt 2, and the lower end portion is pressed as shown in FIG. A bulging hem 1c is formed in the anchor bolt 2, and axial force is introduced to the anchor bolt 2 via the reaction nut 9 by the action of the center hole jack 10, and at the same time, the grip nut 1 is applied to the anchor bolt 2. By tightening by ironing and crimping, axial force is applied and the parts are fixed. After the fixing operation for introducing the axial force is completed, the reaction nut 9, reaction bolt 11, center hole jack 10, die cover 8, and die 7 used for this are removed.
will be removed respectively.

In the case of the method of the present invention, since the reaction force is the anchor bolt itself, the oil pressure of the center hole jack 10 is directly converted into the axial force of the anchor bolt 2. However, when the hydraulic pressure of the jack 10 is released, the axial force returns to some extent, so it is necessary to increase the hydraulic pressure of the jack that produces a predetermined axial force by that amount in advance. Note that when introducing an axial force into the anchor bolt 2, the axial force is generally set at about 70% of the yield point of the material of the anchor bolt 2.

As explained above, the present invention uses a grip nut in which a nut portion that is screwed onto an anchor bolt and a large diameter coupler portion that is loosely fitted onto the anchor bolt is used, and the grip nut is screwed onto the anchor bolt. The base plate is temporarily tightened, and then a die is fitted to the upper part of the grip nut, a reaction nut is connected to the anchor bolt, and a center hole jack is interposed between the die and the reaction nut. By pressing down on the die, the grip nut is crimped onto the outer periphery of the anchor bolt, resulting in many excellent effects as described below.

(1) A center hole jack is used to introduce the axial force, so the specified axial force can be introduced. In addition, since it can move up and down, it can be used even in narrow spaces, and the entire construction process can be performed easily.

(2) Since the grip nut has the same function as a conventional nut, temporary tightening and other operations can be performed in the same way as before, and the grip nut is squeezed by a die and inserted into the threaded part of the anchor bolt. Since it is crimped, there is no risk of it coming loose.

(3) The shape of the grip nut is clearly different before and after applying axial force, so it can be inspected and confirmed at a glance.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the grip nut used in the present invention, Fig. 2 is a longitudinal sectional view showing the anchor bolt in a temporarily tightened state, and Fig. 3 is a longitudinal sectional view showing the state when tension is introduced into the anchor bolt. , FIG. 4 is a perspective view showing the state after the anchor bolt has been tightened. 1...Grip nut, 1a...Nut part, 1
b...Coupler part, 2...Anchor bolt, 3...
...Foundation concrete, 4...Base plate, 6
...Washer, 7...Dice cover, 9...Reaction force nut, 10...Center hole jack, 11...
Reaction bolt.

Claims (1)

[Claims] 1 Screw the grip nut, which has a nut part that screws onto the anchor bolt and a large-diameter coupler part that fits loosely into the anchor bolt, onto the anchor bolt, temporarily tighten the base plate, and then attach the grip nut to the top of the grip nut. At the same time as the die is fitted, a reaction nut is connected to the anchor bolt, a center hole jack is interposed between the die and the reaction nut, the die is pushed down by the action of the jack, and the grip nut is attached to the outer periphery of the anchor bolt. An anchor bolt tightening method characterized by crimping.