JP3123955B2 - High temperature bolted heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature bolting heater for increasing the temperature of a large bolt used for fixing the upper and lower casings of a steam turbine when the bolt is tightened or loosened. .

[0002]

2. Description of the Related Art Bolts used for fixing the upper and lower casings of a steam turbine are larger than general bolts, so that they cannot be tightened or loosened with a spanner or a wrench. . Therefore, by heating the bolt and expanding it in the axial direction, a gap is created between the nut to be tightened and the nut, making the nut easier to rotate,
Tightening and relaxing work.

In such a case, as a bolt heating method,
Conventionally, a method has been adopted in which a resistance wire heating body is inserted into a hole drilled in the axial direction of a bolt, and the bolt is heated from the inside of the hole by generating heat by energizing the resistor.

However, in the case of the heating method using the resistance wire heating body, the efficiency is low due to the indirect heating method of heating by radiation and heat conduction, and it takes a long time to heat the bolt. In addition, since the resistance wire heating body is kept in a high temperature state for a long time, deterioration due to oxidation or the like is severe, and the life is short.

Accordingly, a high-frequency bolt heater has been developed as a bolt heating technique for solving such a problem, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-203948. By using this high frequency bolt heater,
Bolt heating can be performed in a shorter time than in a conventional resistance wire heating type bolt heater.

[0006]

Problems to be Solved by the Invention
No. 8 discloses a high-frequency bolt heater in which an induction heating coil formed of a copper tube or the like wound in a hairpin shape is inserted into a hole drilled in the axial direction of the bolt, and the induction heating coil is formed. When a high-frequency current is supplied to the bolt, an eddy current is generated on the inner surface of the hole of the bolt close to the induction heating coil, and the bolt itself is heated by Joule heat generated by the eddy current.

[0007] Therefore, the coupling loss, which is a drawback of the high-frequency induction heating method, cannot be eliminated, and not all of the supplied current is used for volt heat generation, resulting in low current efficiency. That is, the conventional high-frequency bolt heater generates a magnetic flux by a high-frequency current of the coil, and further generates a high-frequency current in the bolt by the magnetic flux, thereby generating heat in the bolt. , The influence of the magnetic flux is weakened, and the high-frequency current generated in the volt is smaller than the high-frequency current supplied to the coil.

Further, the induction heating coil disclosed in the above publication has a complicated structure in which a magnetic body is sandwiched between reciprocating lines of a copper tube wound in a hairpin shape and a cross section is formed in a substantially circular shape. It takes a lot of time and effort to produce.

In addition, in the case of a high-frequency induction heating type bolt heater, there is a limit in reducing the size of the heating coil. Therefore, when the heating hole drilled in the axial direction of the bolt is small, it can be inserted into the hole. Therefore, there is a problem that it is extremely difficult to manufacture a heating coil having high heating efficiency.

Accordingly, an object of the present invention is to provide a high-temperature bolting heater which does not require a coil having a complicated structure, can perform volt heating in a short time, and has high current efficiency. is there.

[0011]

When a high-frequency current is applied to one conductor, the current flows intensively on the outer periphery of the conductor due to the skin effect. However, as shown in FIG. 6
When a round-trip line is formed by making 0 into a U-shape, and a high-frequency current flows from the power supply device 61 to the conductor 60, the current concentrates and flows on the opposing portion of the conductor 60 due to the proximity effect which is a kind of skin effect. That is, as shown in FIG. 6A, a current concentration portion 62 is generated at a portion where the conductor 60 faces. In this case, as the distance between the opposing portions is smaller and the frequency of the high-frequency current is higher, the degree of current concentration increases.

The high-temperature bolt-tightening heater of the present invention heats a bolt by utilizing such a characteristic characteristic of a high-frequency current, and has a heating hole formed in the axial direction of a conductive bolt. A conductor that can be inserted into the heating hole and held in an insulated state, a conducting member that partially conducts the conductor and the bolt inserted into the heating hole, and an axial direction along the conductor from the conducting member. A power supply unit separately mounted on the conductor and the bolt at a remote position, and a power supply device for supplying a high-frequency current to the power supply unit are provided.

The conductor of the high-temperature bolt-tightening heater of the present invention having such a configuration is inserted into a heating hole drilled in the axial direction of the bolt, and the conductor and the bolt are partially connected by a conductive member. When conducting, when a high-frequency current is supplied from the power supply device to each of the power supply units mounted on the conductor and the bolt, the proximity effect described above causes the current round-trip line to be closest to the inner periphery of the heating hole and High-frequency current flows intensively around the conductor. Therefore, the inner peripheral portion of the heating hole rapidly generates heat by Joule heat, and the heat is conducted to raise the temperature of the entire bolt.

As described above, the high-temperature bolt-tightening heater according to the present invention can raise the temperature of the bolt in a short time because high-frequency current flows directly through the bolt to generate heat, and has high current efficiency because there is no coupling loss. In addition, due to the proximity effect of the high-frequency current, the high-frequency current flows intensively in the inner peripheral portion of the heating hole, so that a necessary portion can be intensively heated.
Further, by changing the position of the conducting member that partially conducts the conductor and the bolt in the heating hole, it is possible to increase, decrease, or change the portion where the high-frequency current is concentrated, thereby preventing an excessive current. it can.

In this case, since the conductor in the heating hole is kept insulated from the bolt, a high-frequency current flows between the conductor and the bolt in a portion other than the conductive member, and the concentration of the current fluctuates. Nothing to do. Since the conductor only needs to efficiently conduct a high-frequency current, a coil having a complicated structure such as a conventional high-temperature bolting heater of a high-frequency induction heating type is unnecessary.

In the high-temperature bolt-tightening heater according to the present invention, the conductor inserted into the heating hole is heated by the heated bolt and may be damaged. A cooling mechanism for preventing overheating by passing and circulating a cooling medium such as liquid or gas in each pipe may be provided.

In the high-temperature bolt-tightening heater according to the present invention, it is desirable that the power supply device can supply a high-frequency current in a frequency range of 1 KHz to 90 KHz. As described above, the proximity effect of the high-frequency current becomes more remarkable as the frequency of the high-frequency current becomes higher, and has a property of increasing the concentration of the current.
By supplying a high-frequency current in the range of 0 KHz, a necessary portion of the volt can be heated intensively in a short time, and the current efficiency is good.

In this case, it is desirable that the appropriate frequency of the high-frequency current be set in accordance with the magnitude of the loss in the cable electrically connecting the power supply device and the high-temperature bolting heater or the magnitude of the proximity effect. In the case of high-frequency current, cable loss is large, and the proximity effect tends to become more pronounced as the frequency increases.In addition, since it is not only the inner peripheral surface of the bolt but the entire bolt that actually needs to be heated, It is necessary to determine the frequency in consideration of this point.

The frequency of the supplied high-frequency current is 1
When the frequency is lower than KHz, the proximity effect is reduced, and a current flows through the whole, requiring a high voltage and a large current, and the cable loss increases. Also, 90KH
When it is larger than z, the inner peripheral surface of the bolt tends to be higher in temperature than the entire bolt due to the remarkable effect of the proximity effect, and there is a possibility of overheating.

On the other hand, the voltage of the high-frequency current to be supplied is desirably 10 V to 90 V. In this case, the appropriate voltage is set according to conditions such as cable cost, danger to the human body, and cable length. If the voltage of the supplied high-frequency current is smaller than 10 V, a large current is required to supply the electric power necessary for heating, and the thickness and weight of the cable are increased. If the voltage is larger than 90 V, leakage due to contact or the like may occur. The risk of electric shock increases.

Further, the high-temperature bolt-tightened heater according to the present invention may have a structure provided with locking means for detachably locking the conductive member in the heating hole. With such a structure, when performing bolt tightening / relaxing work, it becomes possible to easily mount the conductor in the heating hole and withdraw after the work is completed in a short time. The efficiency of the tightening / relaxing operation can be improved.

Further, in the high-temperature bolt-tightening heater according to the present invention, as a locking means for detachably locking the conductive member in the heating hole, an expansion / contraction mechanism for expanding / contracting the conductive member in the radial direction of the heating hole is provided. The structure provided may be provided. With such a structure, the conductive member can be easily inserted into the heating hole if the conductive member is in the contracted state, and can be locked in the heating hole if the conductive member is in the widened state after the insertion. Therefore, the work of attaching and detaching the conductive member in the heating hole becomes easy.

In this case, a mechanism that expands and contracts the conductive member in the radial direction by compressing and expanding the conductive member in the axial direction with a conductor can be provided as the expansion / contraction mechanism. With such a structure, the conductive member in the heating hole can be attached and detached by operating the conductor, so that workability is improved.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view showing a high-temperature bolting heater according to an embodiment, FIG. 2 is an explanatory view showing a heat generation principle by the high-temperature bolting heater, and FIG. 3 is a partially enlarged view of FIG.

As shown in FIG. 1, a high-temperature bolt-tightening heater 10 according to the present embodiment is inserted into a heating hole 12 formed in the axial direction of a metal bolt 11 so that the metal bolt 11
A conductor 13 capable of holding the conductor 13 and the metal bolt 11 at the lower end of the conductor 13 inserted into the heating hole 12; , Power supply units 15 and 16 provided separately on the conductor 13 and the metal bolt 11,
A power supply device 17 that supplies a high-frequency current to the power supply units 15 and 16 via a power supply cable 18 is provided. Power supply unit 1
Set handles 15 s and 16 s for attaching and detaching to and from the power supply cable 18 are provided in 5, 5.

The power supply section 15 supplies a high-frequency current to the bolt 11 via a fixing member 19 mounted on the upper outer periphery of the bolt 11. Further, the fixing member 19 can be tightened and loosened by rotating the set handle 25, so that the fixing member 19 can be easily attached to and detached from the bolt 11.

After setting the high-temperature bolting heater 10 in this way, the power supply unit 17 supplies power to the power supply units 15 and 16.
When a high-frequency current is supplied to the heater, the high-frequency current flows intensively on the inner circumference of the heating hole 12 and the outer circumference of the conductor 13 where the current reciprocating line is closest due to the proximity effect as shown in FIG. The inner peripheral portion of the heating hole 12 rapidly generates heat by Joule heat, and the heat is conducted to raise the temperature of the entire metal bolt 11.

As described above, in the high-temperature bolt-tightening heater 10 of the present embodiment, the high-frequency current is caused to flow directly to the metal bolt 11 to generate heat, so that the temperature can be raised in a short time. Also, since there is no coupling loss, the current efficiency is high. Also, due to the proximity effect of the high-frequency current, the high-frequency current flows intensively in the inner peripheral portion of the heating hole 12, so that the necessary portion can be intensively heated.

Further, by changing the position of the conductive member 14 for partially conducting the conductor 13 and the metal bolt 11 in the heating hole 12, it is possible to increase or decrease or change the portion where the high-frequency current is concentrated. Therefore, an excessive current can be prevented. In this case, the conductor 13 in the heating hole 12
Is held insulated from the metal bolt 11,
Conductor 13 and metal bolt 1 at portions other than conductive member 14
A high-frequency current flows between them, and the concentration state of the current does not fluctuate freely.

In the high-temperature bolt-tightening heater 10 according to the present embodiment, as shown in FIG.
Has a double structure in which a stainless tube 13s is inserted into the inside, and a stainless tube 13s extending from the lower end of the copper tube 13c is provided with a through hole 14h of the conducting member 14 in a lower portion thereof.
And the stainless steel tube 13 exposed from the through hole 14h
The conducting member 14 is connected to the conductor 13 by screwing the bolt 20 to the lower end of the s. A through hole 13h is formed below the stainless tube 13s.

Therefore, when air is supplied into the copper tube 13c from the air supply port 22 provided above the conductor 13, a space formed between the inner periphery of the copper tube 13c and the outer periphery of the stainless steel tube 13s is formed. 21 through the lower through hole 13
h, enters the stainless steel tube 13s, rises as it is, and is discharged outside through the exhaust port 23 at the upper end. As described above, since the conductor 13 has a double pipe structure and the conductor 13 is cooled by allowing air to pass through each pipe,
The conductor 13 can be prevented from being damaged or deteriorated by the heat generated by the bolt 11.

On the other hand, in the high-temperature bolting heater 10, the frequency of the high-frequency current supplied from the power supply 17 is 10
The frequency can be adjusted in the range of KHz to 90 KHz and the voltage can be adjusted in the range of 10 V to 90 V. In this embodiment, the frequency of the high-frequency current is set to 50 K in order to heat the metal bolt 11.
When the frequency was set to 50 Hz and the voltage was set to 50 V, the metal bolt 11 could be heated intensively in a short time, and the current efficiency was good.

In the actual bolt heating operation,
The frequency and voltage of the high-frequency current supplied by the power supply 17 are determined by the size of the volt to be heated and the power supply cable 18.
It is set according to the conditions such as the thickness and length of the work and ensuring the safety for workers.

In the high-temperature bolt-tightening heater 10 of the present embodiment, as shown in FIGS. 3 and 4, the entire conducting member 14 has a substantially cylindrical shape, and the upper opening 14a is formed in a funnel shape. A plurality of slits 14s formed in the direction and a reduced diameter portion 14r are provided, and a bolt holding portion 14b is provided at a lower end. Therefore, the conductive member 1 is connected to the conductor 13.
When the set handle 24 attached to the upper end of the stainless tube 13s is rotated in a state in which the stainless steel tube 4 is connected, the lower end of the copper tube 13c slides through the upper opening 14a by screwing the stainless tube 14s and the bolt 20. 14h through hole
The inside and outside of the conductive member 14 can be expanded and contracted in the radial direction.

That is, when the set handle 24 is rotated clockwise, the lower end of the copper tube 13c enters the through hole 14h from the upper opening 14a of the conductive member 14 by screwing the stainless tube 13s and the bolt 20 together. Conducting member 1
4 is expanded in the radial direction, so that the conductive member 14 is connected to the heating hole 1.
2 can be locked.

When the set handle 24 is rotated counterclockwise, the lower end of the copper tube 13c separates from the upper opening 14a of the conductive member 14, and the conductive member 14 is reduced in diameter in the radial direction. When inserting or removing 13 into heating hole 12, work is performed in a reduced diameter state.

As described above, the conductive member 14 can be expanded and contracted only by rotating the set handle 24, whereby the high-temperature bolted heater 10 is mounted in the conductor 13 and the conductive member 14 in the heating hole 12. In addition, since the withdrawal can be easily performed in a short time, the efficiency of the tightening / relaxing operation can be improved.

[0038]

According to the present invention, the following effects can be obtained.

(1) A conductor which is inserted into a heating hole drilled in the axial direction of a conductive bolt and which can be held in an insulated state from the bolt, a conductor and a bolt which are inserted into the heating hole, and , A power supply unit separately mounted on the conductor and the bolt at a position separated from the conductive member in the axial direction along the conductor, and a power supply for supplying a high-frequency current to the power supply unit When the high-frequency current is supplied to the high-temperature bolting heater set in a predetermined state by providing the device, the high-frequency current flows intensively on the inner periphery of the heating hole due to the proximity effect, so that the entire bolt can be quickly removed. The temperature can be raised and the current efficiency is high because there is no coupling loss.
A coil having a complicated structure is not required.

(2) Since the high-frequency current is concentrated on the inner peripheral portion of the heating hole due to the proximity effect, it is possible to intensively generate heat in a necessary portion, and by changing the position of the conductive member in the heating hole. In addition, it is possible to increase or decrease or change the portion where the high-frequency current is concentrated, and it is also possible to prevent an excessive current. In this case, since the conductor in the heating hole is held in an insulated state from the bolt, a high-frequency current flows between the conductor and the bolt in portions other than the conductive member, and the current concentration portion does not fluctuate. .

(3) The power supply device has a frequency of 10 KHz to 9 KHz.
Since a high-frequency current in the range of 0 KHz can be supplied, a necessary portion of the volt can be heated intensively in a short time, and the current efficiency is good.

(4) By using a structure provided with locking means for removably locking the conductive member in the heating hole, the conductor of the high-temperature bolt-tightening heater can be used when tightening / relaxing work is performed. Can be easily installed in the heating hole and withdrawn after the work is completed in a short time.
Tightening / relaxing work can be made more efficient.

(5) As a locking means for detachably locking the conductive member in the heating hole, a structure having an expansion / contraction mechanism for expanding / contracting the conductive member in the radial direction of the heating hole is provided. If the conductive member is in the contracted state, it can be easily inserted into the heating hole, and after the insertion, if it is in the widened state, it can be locked in the heating hole. The attaching and detaching work of the conductive member becomes easy.

(6) A mechanism for expanding and contracting the conductive member in the radial direction by compressing and expanding the conductive member in the axial direction with a conductor is provided as a mechanism for expanding / contracting the conductive member in the heating hole. Can be performed by manipulating the conductor, so that workability is improved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a high-temperature bolted heater according to an embodiment.

FIGS. 2A and 2B are explanatory diagrams showing the principle of heat generation by the high-temperature bolt-tightening heater shown in FIG. 1, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is a partially enlarged view of the high-temperature bolting heater shown in FIG. 1;

4A is a plan view of a conductive member of the high-temperature bolting heater shown in FIG. 1, FIG. 4B is a front view of the conductive member,
(C) is a partially cutaway front view of the conducting member.

FIG. 5 is a plan view of the high-temperature bolting heater shown in FIG. 1;

FIG. 6 is an explanatory diagram showing a proximity effect of a high-frequency current;
(A) is a top view of a U-shaped conductor, (b) is a front view of a U-shaped conductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 High temperature bolt fastening heater 11 Metal bolt 12 Heating hole 13 Conductor 13c Copper tube 13s Stainless steel tube 13h Through hole 14 Conducting member 14a Upper opening 14b Bolt holding portion 14h Through hole 14r Reduced diameter portion 14s Slit 15, 16 Power supply portion 15s, 16s, 24, 25 Set handle 17 Power supply device 18 Power supply cable 19 Fixing member 20 Bolt 21 Space 22 Air supply port 23 Exhaust port

Claims (5)

(57) [Claims] 1. A conductor inserted into a heating hole drilled in the axial direction of a conductive bolt and capable of being held in an insulated state from the bolt, and the conductor inserted into the heating hole. A conductive member that partially conducts the bolt, a power supply unit that is separately mounted on the conductor and the bolt at a position that is separated from the conductive member in the axial direction along the conductor, and the power supply unit A high-temperature bolting heater comprising a power supply for supplying high-frequency current to the heater. 2. The power supply device according to claim 1, wherein said power supply device has a frequency of
2. The high-temperature bolting heater according to claim 1, wherein a high-frequency current in a range of KHz can be supplied. 3. The high-temperature bolt-tightening heater according to claim 1, further comprising locking means for removably locking said conductive member in said heating hole. 4. The high-temperature bolt-tightening heater according to claim 3, wherein an expansion / contraction mechanism for expanding / contracting the conductive member in a radial direction of the heating hole is provided as the locking means. 5. The high-temperature bolt according to claim 4, wherein the expanding / contracting mechanism includes a mechanism for expanding / contracting the conductive member in the radial direction by compressing and expanding the conductive member in the axial direction with the conductor. Tightening heater.