JPH10249655A - Extracting method of sticking bolt and extractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract such a bolt as being stuck fast by means of a deterioration in a seizure preventive or the like easily in a short time without entailing any damage to it. SOLUTION: A mixed solvent consisting of a high boiling point aromatic hydrocarbon and an alcohol is poured into a thread part gap 18 of a stuck bolt 16 from a solvent injector 20. A return torque is impressed on the bolt 16 by a torque wrench, and in time of unrotatableness (torque is detectable), an ultrasonic vibrator 30 is excited by a high-frequency pulse oscillator 52 of a control unit 50, and thus an ultrasonic vibration is imparted to a thread part 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing a general bolt for fastening a structure or the like and facilitating removal of the bolt.

[0002]

2. Description of the Related Art Seizure or sticking of bolts to which members are fastened may make it difficult to remove the bolts.
Normally, the case where the screw portion of the bolt bites or the metal is welded together is called seizure, and the case where the anti-seizure agent intervening in the screw portion is altered and solidified is called fixation.

When it is necessary to remove bolts for disassembly and inspection of the equipment, the bolts are tightened by applying an anti-seizure agent. In particular, the frequency of bolt stiction is high in equipment used under high temperature and high pressure, such as thermal and nuclear power plants.
It takes time for sampling work, which is a bottleneck for regular inspection.

Removal of the fixing bolts actually performed at the time of inspection of a power plant or the like is based on a method of injecting a lubricant into the vicinity of a screw portion, or a method of applying a large return torque using an impact wrench or a hydraulic wrench. If the bolt still does not come off, the remaining part of the bolt other than the threaded portion is cut off, a drilled hole is formed concentrically with the bolt, and the remaining bolt is cut off with a drill or the like.

Japanese Patent Laid-Open Publication No. 6-63872 discloses a method of removing a bolt by applying vibration to the bolt.
No. 396 and the like. In the former method,
Attach a vibrator to the upper part of the stud bolt fixed to the screw hole, inject the lubricating permeate into the stud bolt stud, then peel off the fixed part by vibration, let the lubricating permeate penetrate into the gap, and loosen the torque. To reduce In the latter method, a vibrator is held in a stud bolt attaching / detaching device, and stud bolts that are stuck and cannot be removed are removed by applying a vertical vibration.

[0006]

The method of spraying or applying a lubricant to the vicinity of the threaded portion of a fixed bolt is simple and widely used. However, it is difficult for the lubricant to penetrate the entire threaded portion only near the upper end of the threaded portion, and lacks certainty. In addition, when an impact wrench or a hydraulic wrench is used, excessive force is likely to be applied to the fixing screw portion, and it is difficult to apply the device to a device that is difficult to repair when the female screw side is damaged. The resection method requires a grinder and a drilling machine, and requires a long working time. Moreover, there is a risk of damaging the female screw side and must be performed by a skilled worker.

On the other hand, the fixing bolt removing method disclosed in the above-mentioned publication physically separates the fixed portion by vibration, and requires a relatively large mounting of a vibrator, and depending on the bolt size and fastening position. May be difficult to apply.

It is an object of the present invention to provide a method and apparatus for overcoming the above-mentioned drawbacks and limitations of the prior art and for easily or reliably extracting a fixing bolt without damaging the bolt.

[0009]

The basic mechanism of the present invention is to dissolve an anti-seizure agent which is interposed in a thread portion and causes adhesion by a specific solvent, and to dissolve the solvent into the entire thread portion. To provide ultrasonic vibration to promote penetration.

In other words, the object of the present invention is to provide a method of removing a bolt by loosening a fixing state of a bolt for fastening a member or the like, by injecting a solvent into a threaded portion of the bolt and applying a return torque to the bolt, This is achieved by irradiating the bolt with ultrasonic waves when rotation of the bolt is impossible.

As the solvent, a mixed solvent of high-boiling aromatic hydrocarbons and alcohols having solubility in carbonized oils and fats, which are intervening substances causing fixation, is used.

The ultrasonic wave is applied to the head of the bolt and / or
Alternatively, continuous irradiation is performed from a member on the female screw side to a side portion of the bolt. Further, when the rotation of the bolt is difficult even after a lapse of a predetermined time from the irradiation of the ultrasonic wave, the bolt is further vibrated vertically from the head of the bolt.

At first glance, the present invention utilizes vibration. However, it does not generate a mechanical peeling action as in the known example, but utilizes static ultrasonic vibration that is not felt by the body, and the chemical reaction between the solvent and the inclusions in the screw part through the micro vibration. It promotes the permeation of the solvent (liquefaction of inclusions) by accelerating, so to speak, acts like a catalyst. According to the experiment, the return torque when using the ultrasonic irradiation is reduced by about 50% as compared with the case using only the solvent. In addition, the effect appears when the ultrasonic irradiation time is about 5 minutes, and the effect on the working time is small. In addition, since the small and lightweight ultrasonic vibrator is in contact with the bolt head or the bolt stud member side, there is little difficulty in application due to the bolt shape and the fastening position.

Further, in the present invention, the solvent to be used is a mixed solvent of a high-boiling aromatic hydrocarbon and an alcohol, such as an alkylbenzene having 9 to 10 carbon atoms in the former, and 3-methyl-3-methoxy- in the latter. Since a mixture of 1-butanol at a predetermined ratio is used, the return torque is reduced by about 50% as compared with a conventional commercially available solvent. It drops to 4.

A bolt extracting apparatus to which the method of the present invention is applied has an injector for injecting a solvent into a threaded portion of a bolt, and an ultrasonic vibrator for applying ultrasonic waves to a threaded portion of the bolt from the side. A holder for holding the injector above the screwed portion, and a holder for holding the ultrasonic vibrator so as to contact the female screw side member of the screwed portion side. This holder is locked and fixed in place on the female screw side member. The solvent injector may be a pressurized type that injects the solvent into the screw portion, a suction type that evacuates from the screw portion lower end side, or a combination of both.

The extracting device has a bolt loosening mechanism for applying a return torque to the head of the bolt, an ultrasonic transmission circuit for applying a high-frequency pulse to the ultrasonic vibrator, and management and detection of the return torque of the bolt loosening mechanism. And a control device for controlling the timing of the operation of each circuit. According to this, the operation of extracting the fixing bolt after the device is set can be substantially automated.

Further, a vibration mechanism for applying vibration up and down from the bolt head is integrally formed with the bolt loosening mechanism, and a connecting portion for engaging the lower part of the integrated structure with the bolt head is provided. Features. Thereby, it is possible to cope with strong fixation that is difficult to remove even by solvent injection and ultrasonic irradiation.

[0018]

FIG. 2 is a schematic view of a main steam isolation valve of a nuclear power plant to which the present invention is applied. A disk 12 driven by a drive mechanism 15 is mounted on an isolation valve body 11 of the main steam pipe, and a body flange 13 and a bonnet 14 are provided.
It is installed by bolting. When checking the main steam isolation valve, loosen the nut 17 and drive mechanism 15, bonnet 1
4. After removing disk 12, stud bolt 16
Extract. The following is an embodiment applied to a case where the stud bolt 16 is stuck and is difficult to remove.

[Embodiment 1] FIG. 1 shows a configuration of a fixing bolt removing device according to a first embodiment of the present invention. Thread 1 of stud bolt 16 on female thread of body flange 13
8 are implanted. A solvent injector 20 having a through hole 21 for inserting the bolt 16 is disposed on the upper surface of the flange 13. The solvent injector 20 seals the penetrating portion of the stud bolt 16 and the upper surface of the body flange 13 with O-rings 24 and 25, and has an injection port 22 for injecting the solvent under pressure and a cavity 23 for storing the solvent. . The injector 20 is fixed to the holder 40 by members 42 and bolts 44 so that the injector 20 does not move during pressurized injection. The holder 40 is a piece of an L-shaped member 41 and is fixed to a stud bolt hole 19 opened on the lower surface of the flange 13 with a bolt 43. Solvents that are soluble in carbonized oils and fats that have been altered by the anti-seizing agent interposed in the thread of the fixing bolt are suitable.
For example, a mixed solvent of a high-boiling aromatic hydrocarbon and an alcohol is effective.

The ultrasonic vibrator 30 includes a contact 31 at the front and a spring 32 pressing toward the flange 13 at the rear. The ultrasonic vibrator 30 is mounted on a case 33 which also serves as an electric shield and a fixing to the holder 40. The contact surface of the contact 31 has a gentle spherical surface so that vibration can be effectively transmitted from all angles regardless of the size of the fixing bolt. Contact 3
Numeral 1 can be exchanged for a shape suitable for the application place.
The control device 50 includes a timing control circuit 51 and a high-frequency pulse transmission circuit 51, and controls the application of an electric pulse to the ultrasonic vibrator 30 and the ultrasonic irradiation time.

The operation of the bolt removing device according to this embodiment will be described. First, a solvent is injected under pressure into the solvent injector 20.
Next, a torque wrench (a wrench with a torque measuring function), not shown, is attached to the double nut 70 (shown by a dotted line) that is engaged with the thread portion 17 of the stud bolt 16, and a normal return torque is applied. As a result, the sticking is not resolved,
If the bolt 16 does not rotate, the torque is measured.

When the control device 50 detects the measured torque value, it applies a high-frequency pulse to the ultrasonic vibrator 30 to generate an ultrasonic wave, and the ultrasonic wave is applied to the threaded portion 18 of the stud bolt 16 from the side of the body flange 13. Give vibration. The timing control circuit 52 measures the torque at a predetermined time, for example, every 5 minutes from the application of the ultrasonic wave, and decreases the torque even after 20 minutes or more (the normal return torque value of 50).
(About 60%) is notified by an alarm or the like. When the torque decreases, the stud bolt 16 is rotated by the torque wrench, and the stud bolt 16 can be removed.

Next, a description will be given of test results in which the effects of the present embodiment are additionally tested. The fixing bolt used in the test was a 1/3 reduced size model (M20 standard bolt, 40 mm under the neck, pitch 2.5, carbon steel SS-41) of the actual machine. The part was tightened so that the surface pressure of the part became almost the same as that of the actual machine, and heat treatment was performed in an atmosphere of 400 ° C. to simulate a fixed state, and the part was allowed to cool to room temperature. Examples of the solvent include a commercially available solvent A, a solvent B developed by the present inventors (an alkylbenzene having 9 to 10 carbon atoms as a high-boiling aromatic hydrocarbon, and 3-methyl-3-methoxy-1-butanol as an alcohol). Are mixed at a predetermined ratio). The ultrasonic vibrator is a piezo crystal type and has a frequency of 40 kHz.
z, LCK type was used for the torque wrench.

FIG. 3 is a return torque characteristic diagram of the test result. FIG. 6A shows the transition of the return torque when the solvent is injected. In the case of the solvent A, it decreased to about 72% of the initial value after 5 minutes, and to about 65% after 20 minutes. In the case of the solvent B, about 55% of the initial value after 5 minutes, and 4% after 20 minutes.
It has decreased to about 3%.

FIG. 3B shows the transition of the return torque when the application of the ultrasonic wave is performed together with the injection of the solvent. In the case of the solvent A, it decreased to about 55% of the initial value after 5 minutes, and to about 43% after 20 minutes. In the case of the solvent B, the initial value is 2 after 5 minutes.
It decreases to about 5 to 30%, and about 18% after 20 minutes.

According to the test results, it was confirmed that the type of the solvent affected the reduction of the return torque, and the effect of the solvent B used in the present example was remarkable. In addition, it was confirmed that the combined use of ultrasonic waves not only halved the value of the solvent alone but also significantly accelerated the rate of reduction, and reduced the torque to a value that could be extracted by ultrasonic irradiation for approximately several minutes.

In the case of the solvent B shown in FIG. 3B, measured values are shown when the ultrasonic vibrator is installed on the side of the screw portion as shown in FIG. 1 and when it is installed on the upper end of the bolt. ing. There is no great difference between the two measurement results, and it can be seen that the arrangement of the ultrasonic vibrator can be appropriately selected depending on the working environment, such as the side portion and upper portion of the bolt.

FIG. 4 shows a modification of the first embodiment. As shown in the drawing, the ultrasonic transducer 30-2 is arranged at the upper end of the bolt 16. Here, a holder 40 for integrally disposing and fixing the vibrator 30-2 and the solvent injector 20 is omitted. Also, a stud bolt hole 19 is provided in the lower part of the bolt 16.
If there is, the funnel-shaped cup 26 is sealed with an O-ring 27 and arranged on the lower surface of the body flange 13 and suctioned by a vacuuming device (not shown) to further promote the penetration of the solvent into the screw gap. I do.

[Second Embodiment] In the first embodiment, an example has been described in which the measurement of the return torque, the removal of the bolt, and the like are performed using a manual torque wrench. The second embodiment describes a configuration in which these are automated.

FIG. 5 shows the configuration of the bolt removing device according to the present embodiment, and the same reference numerals are given to the same elements as those in FIG. An automatic torque wrench 60 is installed on the head of the stud bolt 16 via a connecting portion 70, and is controlled by a torque detection / control section 53 of the control device 50. The automatic torque wrench 60 takes in the drive air from the drive air hose 61 via a solenoid valve 62 for controlling the intake / exhaust amount, and applies a return torque to the rotation shaft 65 to detect torque and rotate the bolt 16. (Sampling).

The rotating shaft 65 is connected to a connecting portion 70 by a double nut or the like at the upper end of the bolt 16 by a socket 66 that is replaced according to the nut diameter, such as a socket wrench.
Is linked to The return torque that increases or decreases according to the amount of air for driving (pressure) is periodically detected by the torque sensor 64 and used for control of the timing control unit 51. Since the mechanism of the automatic torque wrench 60 has a well-known mechanical structure,
Detailed description is omitted. In addition, various well-known mechanical structures such as an electromagnetic drive method can be employed.

FIG. 6 shows an operation procedure of the bolt removing device according to the present embodiment. This procedure starts with solvent injection (S101). Thereafter, the timing control unit 51 sends the driver 6 via the solenoid valve 62 from the torque detection / control unit 53.
3, a normal return torque is continuously applied (S102),
The torque is measured (S103). At this time, if the bolt 16 is rotated by the applied torque, the bolt can be removed (torque detection becomes difficult). Note that S103
Instead of the torque measurement described above, a bolt rotation angle may be measured.

On the other hand, when torque is detected as a result of the inability to rotate the bolt, the timing control unit 51 applies an electric pulse to the ultrasonic vibrator 30 from the high frequency pulse transmitter 52 to irradiate the screw unit 18 with ultrasonic waves. Perform (S10
4). After the ultrasonic irradiation, the timing controller 51 monitors whether the preset time 1 or 2 has been reached (S105), and returns to step S103 for each set time 1 (for example, 1 minute) to repeat the above processing. On the other hand, if the time exceeds the set time 2 (for example, 20 minutes), it is determined that it is difficult to eliminate the bolt fixation, and the process is terminated. The set time 1 may be changed so that, for example, after a lapse of 5 minutes from the start of the measurement, it is repeated every 5 minutes. Further, when the bolt removal is successful or impossible, the control device 50 may notify by an alarm or a display.

According to the present embodiment, the work of removing the fixing bolt can be automated, and the efficiency of the disassembling work in many places of the equipment at the time of regular inspection can be promoted. The solvent injector 2
Regarding 0 and the like, the operation may be controlled by the control device 50.

[Embodiment 3] In Embodiments 1 and 2, most of the fixing bolts which were conventionally difficult to extract can be extracted. However, when it is difficult to remove the bolt, it may be effective to strike the bolt and vibrate it up and down. In the third embodiment, for example, a striking device that moves up and down by being inserted into the rotating shaft 65 of the automatic torque wrench 60 in FIG. 5 is provided, and when the return torque does not decrease below the threshold value, the striking device is moved down. Then, an operation procedure for applying mechanical vibration to the upper portion of the bolt 16 is added.

FIG. 7 shows an operation procedure of the bolt removing device according to the present embodiment. Step S106 is added to the procedure of the second embodiment. That is, when the set time is 2 (for example, 10 minutes), vibration is applied to the bolt in the up and down direction by the striker together with the ultrasonic irradiation. Also in this case, if the set time 3 (for example, 20 minutes) is exceeded, it is determined that it is difficult to remove the bolt fixation, and the process is terminated.

According to this embodiment, the solvent and the ultrasonic vibration are effective for dissolving the adhered substance, and the mechanical vibration is effective for the seizure such as biting of the screw portion. I do.

[0038]

According to the bolt removing method of the present invention, since the solvent is injected into the fixing screw portion and the ultrasonic vibration is applied, the dissolution speed of the screw intervening substance is increased to promote the penetration of the solvent, and the bolt is removed. This has the effect of eliminating sticking and facilitating removal. Further, since the developed specific mixed solvent is used as the solvent, this effect is promoted. Alternatively, the combined use of the ultrasonic vibration and the mechanical vibration due to the impact is effective in removing a more difficult bolt. Further, the work is simple, safe, and requires no skill, so that personnel can be easily secured during regular inspection work and the like. Further, since the working operation for the bolts and female threads can be avoided, not only can the bolts be reused, but there is no risk of damaging the equipment.

According to the bolt removing device of the present invention, the injection of the solvent and the irradiation of the ultrasonic wave into the screwed portion of the bolt are facilitated, so that the working efficiency is improved. Further, work steps including ultrasonic irradiation, detection and control of return torque can be automated, and rationalization of regular inspection work and the like can be promoted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a bolt extracting device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a main steam isolation valve to which the present invention is applied.

FIG. 3 is a characteristic diagram of return torque showing test results according to the first embodiment.

FIG. 4 is a schematic diagram of a bolt extracting device showing a modification of the first embodiment.

FIG. 5 is a configuration diagram showing a bolt extracting device according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing an operation procedure of removing a fixing bolt according to a second embodiment.

FIG. 7 is a flowchart showing an operation procedure of removing a fixing bolt according to a third embodiment.

[Explanation of symbols]

11: Body of main steam isolation valve, 12: Disc, 13 ...
Body flange, 14: Bonnet, 15: Upper drive mechanism, 16: Stud bolt, 17: Upper screw part, 18 ...
Threaded part (planted part), 19… Stud bolt hole,
20: solvent injector, 22: solvent inlet, 23: cavity, 24, 25, 27: O-ring, 26: cup, 30
... Ultrasonic vibrator, 31 ... Contact, 32 ... Pressing spring, 40
... Holder, 50 ... Control device, 51 ... Timing control unit,
52: high frequency pulse transmitter, 53: return torque detection / control unit, 54, 55: signal line, 60: automatic torque wrench,
Reference numeral 61 denotes a driving air hose, 62 denotes a solenoid valve, 63 denotes a driver, 64 denotes a torque sensor, 65 denotes a rotating shaft, 66 denotes a socket (chuck), and 70 denotes a connecting portion (double nut).

Continued on the front page (72) Inventor Yusaku Nishimura 3-2-2 Sachimachi, Hitachi City, Ibaraki Prefecture Within Hitachi Engineering Service Co., Ltd.

Claims (8)

[Claims] 1. A method for removing a bolt by loosening a fixed state of a bolt for fastening a member or the like, wherein a solvent is injected into a threaded portion of the bolt, a return torque is applied to the bolt, and rotation of the bolt is disabled. A method for removing a fixing bolt, comprising irradiating the bolt with ultrasonic waves in such a case. 2. The mixed solvent according to claim 1, wherein the solvent is a mixed solvent of a high-boiling aromatic hydrocarbon and an alcohol having a solubility in carbonized fats and oils as an intervening substance causing fixation. A method for removing a fixing bolt, comprising: 3. The method for extracting a fixing bolt according to claim 1, wherein the ultrasonic wave is applied to a side portion of the bolt from a member on a head and / or a female screw side of the bolt. 4. A bolt that fastens a structure to alleviate a fixation state due to deterioration of an anti-seizure agent or the like at the time of fastening,
In the method of removing a fixing bolt that enables pulling, a mixed solvent such as high-boiling aromatic hydrocarbons and alcohols is injected from above the screwed portion of the bolt and a return torque is applied to rotate the bolt. If it is difficult, irradiate the ultrasonic wave continuously from the structure on the female screw side to the bolt. A method for removing a fixing bolt, wherein the fixing bolt is vibrated. 5. An apparatus for removing bolts for relieving the fastening of bolts for fastening a structure or the like, comprising: an injector for injecting a solvent into a screwed portion of a bolt; Having a vibrator, a holder for holding the injector at the upper part of the screwed portion, and a holder for holding the ultrasonic vibrator so as to abut against the female screw side member of the screwed portion side. Removal device for fixing bolts. 6. The fixing bolt extracting device according to claim 5, wherein the injector is configured to inject the solvent into the screwed portion or to evacuate the lower end of the bolt. 7. A bolt extraction device having a bolt loosening mechanism for applying a rotational torque to a head of a bolt for fastening a structure or the like, comprising: an injector for injecting a solvent in contact with an upper part of a screwed portion of the bolt; An ultrasonic vibrator for applying ultrasonic waves by contacting the female screw side member of the screwed portion side, a transmitting circuit for supplying a pulse signal to the ultrasonic vibrator, and managing and detecting a return torque of the bolt loosening mechanism. An apparatus for removing a fixing bolt, comprising a control device including a torque control circuit. 8. The connecting part according to claim 7, wherein a vibration mechanism for vertically vibrating from a bolt head is integrally formed with the bolt loosening mechanism, and a lower part of the integrated structure is engaged with the bolt head. A fixing bolt extracting device, characterized in that a fixing bolt is provided.