JPS62129405A - Method for adjusting axial force of cable band 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 [Field of Industrial Application] The present invention relates to a method for adjusting the axial force of a bolt used when tightening a cable with a cable hand in order to maintain the main cable of a suspension bridge or the like in a circular shape.

[Conventional technology]

FIG. 3 is a front view of such a cable band 1, which consists of a combination of semicircular divided bodies 1a and la' that sandwich the main cable 3, which is a collection of single cables 3a, and whose end flanges are joined. The cable band bolt 2 is inserted here. In this way, the tightening force of the band 1 is managed by the axial force of the cable band bolt 2, but the axial force introduction work will be explained first.

First, a hydraulically driven bolt tensioner 4 is set at the end of the bolt 2, and the tensioner 4 grips the end of the bolt 1 and pulls the band 1 to remove any play in the nut 5. This work is performed in several steps by controlling the hydraulic pressure of the tensioner 4, and the bolt 2 is pulled and the nut 5 is tightened. Finally, lower the oil pressure of tensioner 4 and remove it.

On the other hand, in the axial force measurement operation, the relative elongation of the reference rod (not shown) and the band bolt 2 is mechanically measured using a measuring device 6 as shown in FIG. FIG. 6 shows the flow of such axial force measurement work.

[Problem that the invention seeks to solve]

By the way, the axial force introduction work and the axial force measurement work could not be performed at the same time. This is due to both the length measuring device 6's requirement that both ends of the bolt 2 must be used when measuring axial force using the mechanical length measuring device 6, and the structural requirement of the tensioner 4. It is something.

Therefore, the axial force adjustment of the conventional cable hand bolt is
As shown in the process chart in the figure, the axial force measurement team follows the axial force introduction team to confirm that the specified axial force has been introduced, and the axial force introduction team re-visits the areas where the specified axial force has not been introduced. Axial force is introduced until a predetermined axial force is introduced to all bolts. For example, in a suspension bridge with a center span of 800 m, approximately 300 cable bands 1 and approximately 4000 band bolts 2 were used.

It takes about 45 days to adjust the axial force once. This adjustment of the axial force of the series of band ports 2 needs to be carried out about three times during the suspension bridge construction period.

An object of the present invention is to solve the inconvenience that in the conventional example, the axial force introduction work and the axial force detection work cannot be performed at the same time, which makes the axial force adjustment work complicated, resulting in an increase in the number of work days and the number of workers. Another object of the present invention is to provide a method for adjusting the axial force of a cable hunt bolt, which can perform the bolt axial force introduction work and the axial force measurement work at the same time, thereby streamlining the work.

[Means for solving problems]

In order to achieve the above object, the present invention attaches a bolt tensioner to one end of a cable band bolt, and when tightening a nut while introducing tension into the bolt, an ultrasonic probe is attached to the other end of the bolt. The gist is to monitor the bolt axial force using ultrasonic waves input to the bolt from the ultrasonic probe.

[Effect]

According to the present invention, the axial force of the bolt can be measured using only one end of the bolt, and the axial force introduction work can be performed simultaneously without removing the bolt tensioner.

〔Example〕

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

FIG. 1 is a partial front view showing an embodiment of the method for adjusting the axial force of a cable band bolt according to the present invention, and FIG. 2 is a flowchart of the same as the above. Similarly to FIG. 1 alla', 2 is a cable band bolt attached to this cable band, and 5 is a nut.

A bolt tensioner 4 is attached to one end of the bolt 2, and an ultrasonic probe 7 is attached to the other end. Then, tension is applied to the bolt 2 using the bolt tensioner 4 using hydraulic pressure, and at the same time, the ultrasonic probe 7 emits ultrasonic waves. This ultrasonic wave enters from the end of the bolt 2, propagates inside, reaches the other end where the bolt tensioner 4 is attached, is reflected there, and reaches the ultrasonic probe 7 or other receiving device again.

Therefore, the axial force of the bolt 2 can be monitored by measuring the propagation time of this ultrasonic wave.

Next, since play occurs in the nut 5 due to the tension of the bolt tensioner 4, the nut 5 is tightened by the amount of play, and the oil pressure of the bolt tensioner 4 is lowered in order to apply an axial force to the bolt 2.

When the oil pressure of the bolt tensioner 4 becomes zero and the axial force introduction is completed, the introduced axial force is detected again by the ultrasonic probe 7 to confirm that the target axial force is introduced. In addition,
It is also possible to simultaneously monitor the bolt axial force introduced by the ultrasonic probe 7 when lowering the oil pressure of the tensioner 4.

If the target axial force is not confirmed, tension is applied again using the tensioner 4 and tightening of the nut 5 is repeated, but if the target axial force is obtained, the tensioner 4 is removed and the band moves to the next band 1.

By the way, instead of performing this work on only one bolt 2, if you perform the axial force adjustment work on all the bolts in one band (approximately 8 to 20 bolts) at the same time, you can adjust the axial force of one bolt in the same hand. Adjustment work for changes in other bolt axial forces due to changes in bolt axial force can be performed while simultaneously monitoring the work, which greatly simplifies the work itself and improves efficiency.

Further, in the above embodiment, one ultrasonic probe is attached to one bolt.
Although axial force detection using individual probes is shown, it is also possible to use a plurality of probes and use their average value in order to increase the reliability of the detected measured values.

Furthermore, as another embodiment, if a receiving ultrasonic probe is attached to the tensioner 4 side so as not to interfere with the work of introducing axial force into the bolt by the bolt tensioner 4,
The axial force adjustment work can also be carried out not only by the ultrasonic reflection method but also by the transmission method.

〔Effect of the invention〕

As described above, the method for adjusting the axial force of a cable band bolt according to the present invention is such that when a bolt tensioner is attached to one end of the cable band bolt and a nut is tightened while introducing tension to the bolt, the bolt tensioner is attached to one end of the cable band bolt. The axial force introduction work and the axial force measurement work can be done at the same time without removing it. This eliminates the need to divide into two teams, the axial force introduction team and the axial force measurement team, and also eliminates the need for re-introduction and re-measurement. Therefore, the target axial force can be introduced in a single axial force adjustment operation, and the number of working days and number of workers for the axial force adjustment operation can be greatly reduced.

[Brief explanation of drawings]

Fig. 1 is a partial front view showing an embodiment of the method for adjusting the axial force of a cable band bolt according to the present invention, Fig. 2 is a flow chart similar to the above, Fig. 3 is a front view of the cable band bolt, and Fig. 4 is a conventional cable band bolt. Process chart for band bolt axial force adjustment work,
FIG. 5 is a partial front view of a conventional axial force measurement operation, and FIG. 6 is a flowchart of the same. ■...Cable band 1a+1a'...Divided body 2
...Cable band bolt 3...Main cable 3a...Cable 4...
Bolt tensioner 5... Nut 6... Length measuring device 7... Ultrasonic probe Applicant: Kobe Steel, Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] When a bolt tensioner is attached to one end of the cable band bolt and the nut is tightened while introducing tension into the bolt, an ultrasonic probe is attached to the other end of the bolt, and the tension is applied to the bolt from the ultrasonic probe. A cable band bolt axial force adjustment method characterized by monitoring the bolt axial force using ultrasonic waves input to the bolt.