JPH03204406A - Bolt tension device and method - Google Patents

Abstract

PURPOSE:To enhance the reliability in bolt-tightening by inserting a screw connecting member with an internal thread part into a through-hole of a bridge member, which abuts on a nut-seating surface, applying axial tension to a bolt by means of an axial tension applying device via the screw connecting device, comparing a signal from a bolt elongation detecting means with a target value for controlling. CONSTITUTION:A bridge member 12 with a through-hole 16 is arranged on nuts N of bolts Bb, Bc, which are situated on both sides of a bolt Ba, which is to be stretched via a sleeve-leg member 14. In addition, a screw connecting member 18, which is threadably engaged with the bolt Ba in the range of an internal thread part 22, is inserted into the through-hole 16, and a hydraulic jack device 26 is placed between a flange part 24 of this member 18 and the bridge member 12. Meanwhile, the elongation of the bolt Ba, which is detected by means of a magnetic scale 42 and a movable piece 44 a measuring instrument main body 40, is compared with a target value by using a controller 70 in order to control a hydraulic jack 26. Accordingly, the elongation of the bolt Ba can be maintained at a correct value, and both efficiency and reliability of the tightening work can be enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for applying a predetermined fastening force (tightening is force) in fastening bolts and nuts, and for loosening the fastening force. The present invention relates to a bolt tensioning device and method for tensioning bolts in the axial direction, and in particular to a bolt tensioning device and method suitable for tensioning fastening bolts in large equipment such as a steam turbine casing for power generation.

[Prior Art] When fastening a bolt and nut, which are relatively large and require a relatively large fastening force, the bolt is stretched in the axial direction and deformed within its elastic limit. By tightening the nut in this state and releasing the tension on the bolt after completing the second tightening, a tightening force determined according to the amount of bolt elongation can be applied. Similarly, it has been conventional practice to stretch and deform the bolt within its elastic limit, and then loosen the nut in this state.

A bolt tensioning device for tensioning the bolt in the axial direction has already been proposed in order to tighten and loosen the screw pair as described above. No. 48-66299.

[Problems to be Solved by the Invention] When tensioning the bolt as described above, it is necessary to control the tension in the axial direction of the bolt so that a predetermined fastening force can be accurately obtained during fastening.

The tensile force applied in the axial direction of the bolt and the amount of elongation in the axial direction of the bolt are in a proportional relationship within the inherent elastic limit of the bolt, and the amount of elongation in the axial direction of the bolt and the bolt fastening force can be predicted. Since there is a certain correlation, it is possible to control the setting of the bolt tightening force by monitoring the vibration in the axial direction of the bolt.

In view of the above-mentioned correlation, the main object of the present invention is to provide a bolt tensioning device and method that appropriately controls the tension of a bolt in order to apply a predetermined fastening force.

Conventionally, when tightening bolts for fastening large devices such as flange connection bolts for steam turbine casings for power generation, it has been necessary to use large bolt tensioning devices that can exert up to several hundred tons of tightening force. When fastening multiple bolts using such a large bolt tensioning device, it is necessary to move the bolt tensioning device for each bolt using a power plant overhead crane, which is a costly handling task. Ta.

Another object of the present invention is to provide a mobile bolt tensioning device with excellent workability that does not require costly handling work during port tensioning in large equipment such as a single-turbine turbine casing for power generation. It's about doing.

(Means for Solving Problem J) According to the present invention, a bridge member that directly or indirectly abuts the seating surface of a nut at both ends;
a threaded connection member that is movably inserted into a through hole provided in an intermediate portion of the bridge member in the axial direction thereof and has a female threaded portion that is threadedly engaged with a bolt; and an axial force that applies an axial force to the threaded connection member. elongation detection means for detecting the elongation amount of the bolt in the axial direction; and applying the axial force based on a comparison between the elongation detected by the elongation detection means and a predetermined bolt elongation target value. This is achieved by means of a bolt tensioning device having control means for controlling the actuation of the means.

The bolt tensioning device as described above may be movably provided on a track extending along the arrangement direction of a plurality of bolts to be tensioned, and may constitute a mobile bolt tensioning device, which is a large-sized device. It is suitable for use as a bolt tensioning device for a steam turbine casing.

In addition, as a bolt tension method using a plurality of bolt tensioning devices as described above, the bolt number is registered for each of the plurality of bolts to be tensioned, and a bolt elongation target value is set for each of them. This is achieved by a bolt tensioning method characterized by operating several bolt tensioning devices to tension a plurality of bolts.

[For production]

According to the configuration described above, the amount of elongation of the bolt is measured in an in-process method, and the tension of the bolt by the axial force applying means is controlled based on the comparison between this amount of elongation and a predetermined target bolt elongation value. .

In a mobile bolt tensioning device, the bolt tensioning device is guided by a track and automatically moves a plurality of bolts in the arrangement direction.

Further, in the bolt tensioning method according to the present invention, a plurality of bolts can be simultaneously tensioned to a predetermined bolt elongation target value by using a plurality of bolt tensioning devices.
Accordingly, a plurality of bolts can be tightened simultaneously.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows one embodiment of a bolt tensioning device according to the invention. In Fig. 1, Ba is the bolt to be tensioned, Bb and Bc are the bolts adjacent to both sides of the bolt Ba to be tensioned, and N is the nut to be screwed into each of the bolts Ba-Bc. S: Indicates the seating surface of Yo-nut N.

The bolt tensioning device is indicated generally at 10 in FIG. 1 and includes a bridge member 12. The bridge member 12 is adapted to rest at its both ends on the upper surface of a nut N attached to the bolts Bb and Bc on both sides of the pole Ba to be tensioned via the sleeve leg member 14. As a result, the bridge member 12 is arranged substantially horizontally so as to straddle the bolt Ba to be tensioned.

A through hole 16 is provided in the center of the bridge member 12 and extends vertically through the bridge member 12, and a snap connection member 18 is provided in the through hole 16 so as to be movable in the axial direction, that is, in the vertical direction in the figure, and to be replaceable. Possibly inserted. The screw connection member 18 is
This is constructed as a hollow body having a hollow hole 20 passing through it in the axial direction, that is, in the vertical direction in the figure, and a female threaded portion 22 is formed near the lower end of the hollow hole 20 to be screwed into the bolt Ba to be tensioned. has been done. The screw connection member 18 has a flange portion 24 at its upper end, and an annular hydraulic jack device 26 is provided between the flange portion 24 and the bridge member 12 as an axial force applying means.

The hydraulic jack device 26 includes an annular cylinder member 28 and an annular piston member 30 fitted therein,
Cylinder chamber 34 kept liquid-tight by seal member 32
By supplying hydraulic pressure from the hydraulic pressure supply/discharge port 36, the piston member 30 is driven upward in the figure.

Note that eye bolts 13 for hanging are attached to both ends of the bridge member 12.

An elongation detection device 38 is provided in the hollow hole 20 of the screw connection member 18.
is located. The elongation detection device 38 has a magnetic scale 42 fixedly disposed within a fixed measuring device main body 40, and the magnetic scale 42 is engaged with the adapter part t46 by a movable element 44. The adapter member 46 is fitted with a predetermined fit into a center hole Bh formed in the bolt Ba at the rond part 48 for centering, and the spring force of the spring 50 causes the flange part 52 to be inserted into the upper surface of the bolt Ba. It is pressed against the bolt Ba and engages with the bolt Ba with a predetermined contact pressure.

The adapter member 46 moves upward in the figure with respect to the measuring instrument body 40 against the spring force of the spring 50 in response to the elongation of the bolt Ba in the axial direction, and moves the mover 44 of the magnetic scale 42 by the amount of elongation. The magnetic scale 42 is moved upward according to the amount of movement of the mover 44.
It outputs an electric signal related to the amount of elongation of a in the axial direction.

Hydraulic pressure is supplied to and discharged from the cylinder chamber 34 of the hydraulic jack device 26 by a hydraulic device 54.

The hydraulic system 54 includes a hydraulic pump 58 rotationally driven by an electric motor 56, a relief valve 60, a pressure gauge 62, a pressure switch 64, an electromagnetic switching valve 66, and a drain valve 67. The supply and discharge of hydraulic pressure to and from the cylinder chamber 34 is controlled by switching the valve 66.

The magnetic scale 42 generates an electric signal related to the amount of elongation of Pol 1-Ba as described above, and displays this on the elongation amount display device 68.
and the control device 70. The control device 70 includes a bolt elongation target value setting means 72 and a bolt elongation target value E set by the bolt elongation amount setting means 72.
Comparison means 74 is provided for comparing the actual elongation amount Er of port t-Ba detected by the magnetic scale 42. The comparison means 74 compares the elongation amount Er with the bolt elongation target value Et, and controls the operation of the electromagnetic switching valve 66 based on this comparison. This control is
Specifically, a signal related to the elongation amount Er of the bolt Ba is repeatedly acquired from the magnetic scale 42, and this is compared with a reference signal indicating the bolt elongation target value Et. If it is determined that the value Et has been reached, the electromagnetic switching valve 66 is operated to cut off the supply of hydraulic pressure to the cylinder chamber 34.

Next, the bolt tensioning operation procedure using the bolt tensioning device according to the present invention and the subsequent bolt tightening operation will be explained using FIGS. 2(a) to 2Cd).

First, as shown in FIG. 2 (al), temporarily tighten the nut N to the bolt Ba as the first spring, and then place the sleeve leg member on the nut N already attached to the bolts Bb to Bc on both sides. 14 is placed.

Next, as shown in FIG. 2(b), as a second step, the bolt tensioning device 10 is moved directly above the bolt Ba by the handling device using the eye bolt 13.
By rotating the threaded connection member 18, the female threaded portion 22 and the bolt Ba are screwed into each other. Thereby, the threaded connection member 18 and the bolt Bc are rigidly connected in the axial direction.

Next, as shown in FIG. 2(C), as a third step, a hydraulic hose for supplying hydraulic pressure to the cylinder chamber 34 is connected, an elongation detection device 38 is installed, and a hydraulic jack device is installed. Hydraulic pressure is supplied to the cylinder chamber 34 of No. 26, and the threaded connection member 18 starts pulling the bolt Ba in the axial direction.

As a result, the bolt Ba is elongated and deformed in the axial direction, and when this reaches a predetermined value, that is, the bolt elongation target value, the electromagnetic switching valve 66 is automatically switched by the control device 72, whereby the cylinder chamber 34 is Hydraulic pressure is sealed and the pressure is maintained.

Next, as shown in FIG. 2(d), the fourth step.

As a step, the nut B is tightened, and after this is completed, the oil pressure in the cylinder chamber 34 is discharged by the oil drain valve 67. After this, the amount of expansion of the pole 1-Ba is measured again by the amount of expansion detection means 38, and it is determined that this is permissible. After confirming that it is within the specified value, the tightening process is completed.

3 and 4 show another embodiment of the bolt tensioning device according to the invention. This example is an application example in the case where the bolt arrangement line is not in a straight line, and in this example, four poles (Bb, Bc, Bd, Be) on both sides of the bolt Ba to be pulled are A bent leg member 76 is used to support the bridge member 12 by sitting on the upper surface of each of the nuts 1-N, and the bent leg member 76 is connected to the nuts N of the outer poles 1-Bd and Be by means of fastening nuts 78. It is set to be fixed.

FIG. 5 shows an example of a thin air turbine casing for power generation as an example of an object to which a bolt is tensioned by the bolt tensioning device according to the present invention.

In FIG. 5, reference numeral F indicates a horizontal flange surface forming a nut seating surface, and reference numeral H indicates a bolt hole provided in this flange surface F. The bolt holes H have an inner diameter of about 80 to 150 mm and are distributed in about 5 to 6 different types.

FIG. 6 schematically shows the overall configuration of a movable bolt tensioning device according to the present invention applied as a bolt tensioning device for a steam turbine casing as shown in FIG.

The mobile bolt tensioning device shown in FIG. 6 has a handling track that extends along the arrangement direction of a plurality of bolts to be tensioned, that is, approximately along the outline of the flange surface F of the steam turbine casing. 80 and a plurality of bolt tensioning devices IO movably provided along the extending direction of the handling track 80. In the illustrated embodiment, the bolt tensioning devices 10 are provided in four positions. Each of the desks is provided with an elongation N detection device 38 for detecting the amount of elongation of the bolt in the axial direction. The bolt tensioning device 10 is configured such that hydraulic pressure can be selectively applied to the cylinder chambers 34 individually from the hydraulic device 54 through the hydraulic hoses 82. The operation of the hydraulic system 54 is controlled by a control device 70, and the control device 70 receives a signal 1.
84 gives a signal regarding the amount of elongation of the bolt in the axial direction detected by the elongation amount detection device 38, and controls the operation of the hydraulic device 54 based on a comparison between this and a predetermined bolt elongation target value. It has become.

In this case, by registering the bolt number in advance in the control device 70 for each bolt to be tensioned, and setting the bolt elongation target value individually for each bolt, it is possible to individually operate the plurality of bolt tensioning devices 10 at the same time. is possible,
This makes it possible to simultaneously elongate and deform a plurality of bolts to their respective elongation target values.

7 and 8 show in detail the handling structure of the mobile bolt tensioning device according to the invention. In FIGS. 7 and 8, parts corresponding to those in FIG. 6 are designated by the same reference numerals as in FIG. 6. The track 80 is composed of a plurality of T-shaped rail members 86 connected to each other by a flange-shaped rail joint member 84, so that it can be disassembled and reassembled, and is a strut temporarily installed on the flange surface F of the steam turbine compartment. 88 is thus installed substantially horizontally above the flange surface F. T-shaped bar member 86 and strut 8
Each of the parts 8 is made of a light metal such as duralumin to reduce weight, and is designed to be easily assembled and disassembled by hand. Note that the support column 88 is a welded structure that can withstand a transportable gravity of about 250 kg.

Gear trolley block 2 hoist 9 is on track 80.
A plurality of 0's are provided so that they can run. Each hoist 90 suspends and supports a bolt tensioning device 10 by a suspension wire 92. The hoist 90 has running wheels made of, for example, urethane material, and moves along the extending direction of the track 80, that is, along a track line that is similar to the bolt arrangement line of the steam turbine casing, so that the bolt tensioning device 10
to a predetermined bolt tensioning position. The hoist 90 is also used to transport bolts used in addition to the bolt tensioning device 10.

In the embodiment shown in FIGS. 6-8, a plurality of bolt tensioning devices 10 are used, and by operating the plurality of bolt tensioning devices 10 simultaneously, as described above,
Tensioning of multiple bolts is performed at the same time, which allows subsequent bolt tightening to be performed at the same time,
Enables uniform bolt tightening.

Note that the number of bolt tensioning devices is not particularly limited to four, and may be less than four or more than four.

Further, in the above embodiment, as the elongation amount detection means,
Although a magnetic scale is used, the present invention is not limited to this, and it may be an optical scale, an ultrasonic scale, or the like.

[Effects of the Invention] According to the bolt tensioning device according to the present invention, the amount of elongation of the bolt is measured using an in-process method, and the amount of elongation and the predetermined amount are The bolt tension by the axial force applying means is controlled based on the comparison with the bolt elongation target value, and this control allows the bolt elongation amount to be set correctly to the predetermined bolt elongation target value. Tightening with S improves reliability.

In the case of a mobile bolt tensioning device, the bolt tensioning device is guided by a trajectory Q and automatically moves multiple bolts in the direction of arrangement, without the need for costly handling work. Tensioning of a plurality of bolts in a large device such as a chamber can be performed with good work efficiency.

Further, in the bolt tensioning method according to the present invention, a plurality of bolts can be simultaneously tensioned to a predetermined bolt elongation target value by using a plurality of bolt tensioning devices.
Accordingly, a plurality of bolts can be tightened simultaneously, and uniform tightening can be achieved.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing one embodiment of the bolt tensioning device according to the present invention 2, and Figs. 2 (a) to (d) show the bolt tensioning operation performed using the bolt tensioning device according to the present invention and the subsequent Bolt tightening is a work explanatory diagram showing the specific steps of the work,
FIG. 3 is a front view showing another embodiment of the bolt tensioning device according to the present invention, FIG. 4 is a plan view of FIG. 3, and FIG. 5 is a bolt tensioning device using the bolt tensioning device according to the present invention. A plan view of the flange portion of the steam turbine casing, FIG. 6 is a schematic configuration diagram showing an embodiment of the mobile bolt tensioning device according to the present invention, and FIG. 7 shows the handling structure of the mobile bolt tensioning device according to the present invention. The plan view shown in FIG. 8 is a front view of FIG. 7. 10... Bolt tension device 12... Bridge member 18... Screw connection member 26... Hydraulic jack device 38... Elongation amount detection device 42... Magnetic scale 54... Hydraulic device 70...・Control device 80...Handling shaft path 90...Hoist

Claims (1)

[Claims] 1. A bridge member that directly or indirectly abuts the seating surface of the nut at both ends, and a bolt that is inserted into a through hole provided in an intermediate portion of the bridge member so as to be movable in the axial direction thereof. a threaded connection member having a female thread that is screwed into the threaded connection member, an axial force applying means for applying an axial force to the threaded connection member, an elongation amount detection means for detecting the amount of elongation of the bolt in the axial direction, and the elongation amount detection means and a control means for controlling the operation of the axial force applying means based on a comparison between the elongation amount detected by the bolt elongation and a predetermined bolt elongation target value. 2. A mobile bolt tensioning device, characterized in that the bolt tensioning device according to claim 1 is movably provided on a track extending along the arrangement direction of a plurality of bolts to be tensioned. 3. A bolt tensioning device for a steam turbine casing, comprising the bolt tensioning device according to claim 1 or 2. 4. A plurality of bolt tensioning devices according to claims 1 to 3 are used, a bolt number is registered for each of the plurality of bolts to be tensioned, and a bolt elongation target value is set for each of the bolts, and a plurality of bolt tensioning devices are used. A bolt tensioning method characterized by operating a bolt to tension a plurality of bolts.