JP2000354975A - Large bolt fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fasten a large bolt by using a simple heating device and a cooling device on a large bolt fastening device to be used to fasten a turbine casing and a large machinery. SOLUTION: A circumference of a bolt 1 and a nut 2 is covered with an outside cylinder 4, an inside cylinder 3 is inserted from an upper part of the outside cylinder 4, the inside cylinder 3 is screwed with a screw part 1a of a head end of the bolt 1, and an inside cylinder flange 3a is made contact with the outside cylinder 4. Steam is supplied from a medium supply port 13a to the outside cylinder 4, flows out from a medium collection port 13b through a passage 12 for medium supply, a plural number of holes 12a for a medium and a circular passage 12b and heats the outside cylinder 4, a valve 11a for medium supply, a collection port 11b, a medium supply passage 10, a hole 10a for the medium and a circular passage 12b are provided on the inside cylinder 3, fleon of a cooling medium is made to flow and cools the inside cylinder 3, the bolt 1 is pulled and extended, a clearance is made between the nut 2 and a fastening object 50, and the nut 2 is rotated and fastened. The bolt 1 is firmly fastened on the fastening object 50 by alternately repeating these heating and cooling on the inside cylinder 3 and the outside cylinder 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening device for a large bolt used for connecting a flange portion of a turbine casing, a large press machine, or the like. This facilitates the mounting and dismounting of the bolts, and enables efficient assembly and disassembly of the casing and the machine.

[0002]

2. Description of the Related Art Conventionally, a bolt applied to a flange of a casing of a turbine is tightened by applying tension to the bolt.
By grasping the tip of the bolt and pulling it with hydraulic pressure, mechanically extending the bolt shaft within the elastic limit and tightening the nut by the amount of extension, or by providing a hole inside the shaft of the bolt, A method has been practiced in which a bolt is expanded by thermal expansion by inserting a heating heater and heating with a heater, and tightening with a nut.

FIG. 9 is a cross-sectional view of a typical example of the conventional large-sized bolt fastening device described above, in which mechanical tension is used. In the drawing, reference numeral 50 denotes an object to be fastened, 51 denotes a bolt, 52 denotes a tightening nut, and 53 denotes a grip nut. 54 is a piston, 55 is a cylinder, 56 is a bolt fastening hole opened at the bottom of the cylinder 55, and 5
7 is a hydraulic passage, and 58 is a hydraulic on-off valve.

In the bolt fastening device having the above structure, the on-off valve 58 is opened and the cylinder 55 is passed through the hydraulic passage 57.
When the oil is supplied to the lower part 60 of the armature, the piston 54 rises and pulls the bolt 51 upward through the grip nut 53. The bolt 51 is extended by this tensile force, and the fastening nut 5
A gap 61 is generated between the workpiece 2 and the workpiece 50. Next, the fastening nut 52 is inserted into the hole 56 and rotated by inserting a tool, the gap 61 is tightened, the hydraulic pressure is released, and the grip nut 53, the piston 54, and the cylinder 55 are removed to complete the fastening.

FIG. 8 is a sectional view showing a typical example of a bolt using an electric heater. In the figure, reference numeral 50 denotes an object to be fastened, 71 denotes a bolt, and 72 denotes a nut. Reference numeral 73 denotes a hole formed in the center of the bolt 71. A heater 74 is inserted into the hole 73 via an insulator (not shown), and current is supplied from the lead wire 75 to the heater 74. . When an electric current is supplied to the heater 74, the bolt 71 is heated by the heat generated by the heater 74, and thermal expansion occurs due to thermal expansion. A gap 76 is formed between the object 70 and the nut 72 due to the thermal expansion of the bolt 72, and the nut 72 is tightened by turning the nut 72 to eliminate the gap. When the current is stopped and the bolt 71 drops to the atmospheric temperature, the bolt becomes stronger. Is concluded.

[0006]

As described above, in the conventional method utilizing mechanical tension shown in FIG. 9, since an ultra-high pressure oil pressure is used, a hydraulic pump, its piping, valves, a hydraulic tank and the like are provided. Need large equipment,
Problems such as oil leakage also occur. In the electric heating system shown in FIG. 10, power supply equipment such as a large-capacity transformer must be separately provided, and in addition to this, a hole for inserting a heater in the center of the fastening bolt itself must be formed. Must
The fastening bolt itself becomes expensive, and there is a problem in the strength of the bolt, resulting in a large bolt. Therefore, in such a bolt fastening device for a turbine casing or a large-sized machine, it has been strongly desired to realize a device capable of easily fastening a bolt by a simple operation with a minimum of special equipment.

Therefore, in the present invention, a relatively simple mechanism is used in a factory such as a turbine, so that a flange or the like of a turbine casing can be easily formed with large bolts without installing a hydraulic power for bolting or a large-capacity power supply. An object of the present invention is to provide a large-sized bolt fastening device that employs a heating and cooling system that can be fastened to a bolt.

[0008]

The present invention provides the following means (1) to (4) to solve the above-mentioned problems.

(1) An inner cylinder which has a flange around the distal end and is screwed to a threaded portion of a bolt which engages with a nut for fastening an object to be fastened, and a predetermined gap is maintained between the inner cylinder and the outer periphery of the nut. A medium that communicates with the inside of a wall around the inner cylinder, the outer cylinder being disposed so as to cover the lower end of the inner cylinder, the lower end of the outer cylinder being in contact with the lower surface of the flange of the inner cylinder, and the lower end being supported by the workpiece. A large-sized bolt having a passage provided with a medium passage communicating with the inside of a wall around the outer cylinder, and further having a tool hole for rotating the nut in either the inner cylinder or the outer cylinder. Fastening device.

(2) In the invention of the above (1), the inner cylinder and the outer cylinder are assembled by combining a plurality of divided parts, respectively.

(3) In the above invention (1), the tool hole is formed by cutting out a part of the lower end of the outer cylinder.

(4) In the invention of the above (1), the tool hole is formed by a notch portion which penetrates an upper flange of the inner cylinder toward a lower portion and cuts a peripheral surface vertically. Features a large bolt fastening device.

According to (1) of the present invention, the outer cylinder is heated when a heating medium, for example, steam is supplied to the outer cylinder for a predetermined time in the outer cylinder.
For example, the inner cylinder is cooled by flowing Freon. As a result, a thermal expansion difference occurs between the outer cylinder and the inner cylinder, and the inner cylinder is pulled upward through the inner cylinder flange. Since the inner cylinder is screwed into the threaded part of the bolt, the bolt is pulled upward, and as a result, a gap is created between the nut and the workpiece, and the nut is rotated by rotating the nut to remove the nut. Can be easily tightened. The rotation of the nut inserts the tool from the tool hole, engages the tool with the groove provided in the nut, and turns the nut.

Next, contrary to the above steps, a cooling medium, for example, chlorofluorocarbon is caused to flow in the medium passage of the outer cylinder to cool it, and a heating medium, for example, steam is caused to flow in the medium passage of the inner cylinder for heating. As a result, a thermal expansion difference occurs between the inner cylinder and the outer cylinder in the same manner as described above, and the bolts screwed with the threaded portions of the inner cylinder are pulled upward, whereby the nut and the workpiece are connected in the same manner as described above. There is a gap between them. This gap facilitates rotation of the nut, and the nut can be rotated and tightened by the tool as described above. In this way, the outer cylinder and the inner cylinder are alternately heated / cooled, cooled / heated, and this is repeated several times, the nuts are rotated, and the objects to be fastened can be firmly fastened with the bolts and nuts.

In the case (2) of the present invention, when a cooling water passage or a steam passage is formed inside the inner cylinder or the outer cylinder so as to communicate with the inner cylinder or the outer cylinder, holes or grooves are formed in the respective divided portions, and these divided portions are formed. By coupling, a passage can be formed inside the inner cylinder or the outer cylinder.

In (3) of the present invention, a hole for rotating a nut can be provided with a simple structure by cutting out the lower end of the outer cylinder for machining of a tool hole, and in (4), a plurality of holes are provided from the upper portion. The tool of the bar-shaped member is inserted, the tool is engaged with the groove of the nut, and the nut can be rotated together with the inner cylinder.

[0017]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an overall longitudinal sectional view of a large-sized bolt fastening device according to an embodiment of the present invention. In the figure, 1 is a bolt, 2 is a nut,
The bolt 1 has a threaded portion 1a, and a nut 2 is screwed to the threaded portion and fastened to the workpiece 50. Reference numeral 3 denotes an inner cylinder, the lower part of which is screwed into the screw portion 1a of the bolt 1, and the inner cylinder flange 3a is formed at the upper part. Reference numeral 4 denotes an outer cylinder, the upper end of which is in contact with the inner cylinder flange 3a, and is slidably inserted in the inner cylinder 3 or inserted with a gap therebetween, and the lower end is mounted on the workpiece 50 through the washer 5 Have been.

Reference numeral 10 denotes a medium supply passage, which is provided in a circular shape inside the inner cylinder 3 and has a medium supply port 11a, as will be described later.
A medium recovery port 11b is provided so that the medium is supplied and collected. Reference numeral 10a denotes a plurality of media holes formed in the inner cylinder 3 in the axial direction around the inner cylinder 3;
Is a circular passage arranged in a circular shape inside the lower part of the.

The medium supply passage 10 in the upper part of the inner cylinder 3 communicates with the plurality of medium holes 10a and the circular passage 10b, and the medium is supplied from the medium supply port 11a. The medium is recovered from the medium recovery port 11b through the use hole 10a and the circular passage 10b.

Reference numeral 12 denotes a medium supply passage, which is provided in a circular shape inside the upper part of the outer cylinder 4 as described later. The outer cylinder 4 is further provided with a medium supply port 13a and a medium recovery port 13b.
Media is supplied and collected. Reference numeral 12a denotes a plurality of media holes formed in the axial direction around the outer cylinder 4, and 12b denotes a circular passage arranged in a circular shape inside the lower part of the outer cylinder 4.

The medium supply passage 12 in the upper part of the outer cylinder 4 communicates with the plurality of medium holes 12a and the circular passage 12b in the lower part, and the medium is supplied from the medium supply port 13a. A plurality of medium holes 12a, circular passages 12
and flows through the medium recovery port 13b.

FIG. 2 is a detailed view showing the inner cylinder 3 in FIG. 1, (a) is a side view, and (b) is an AA in (a).
Sectional drawing, (c) is BB sectional drawing. In these figures, a circular medium supply passage 10 is formed in the upper part inside the inner cylinder 3.
A circular passage 10b is provided in the lower part, and as described above, these two passages communicate with eight medium holes 10a provided in the inner peripheral axis direction of the inner cylinder 3, and the medium is supplied from the medium supply port 11a. It is configured to be supplied and collected from the medium collection port 11b.

An inner cylinder flange 3a is provided above the inner cylinder 3.
Is formed inside the inner cylinder 3 to form the medium supply passage 10, the medium hole 10a and the circular passage 10b. The medium supply passage 10 is divided into three, and the medium hole 10a is divided into three.
After forming the circular passage 10b into the portion 3-3, the portions 3-1, 3-2 and 3-3 are combined by welding or the like to be integrated.

FIG. 3 is a detailed view showing the outer cylinder 4 in FIG. 1, (a) is a side view, and (b) is a CC in (a).
Sectional drawing, (c) is DD sectional drawing. In these figures, a circular medium supply passage 12
In the lower part, circular passages 12b are provided respectively, and these two passages communicate with eight medium holes 12a provided in the axial direction around the inside of the outer cylinder 4, and the medium is supplied from the medium supply port 13a. The medium is supplied and collected from the medium collection port 13b.

The medium supply passage 1 is provided inside the outer cylinder 4.
2. In order to machine the medium hole 12a and the circular passage 12b, the outer cylinder 4 is divided into three parts 4-1, 4-2, and 4-3 at the V and W points, and the medium supply passage 12 is 3-1. Further, after the medium hole 12a is formed into the portion 3-2 and the circular passage 12b is formed into the portion 3-3, the portions 3-1, 3-2 and 3-3 are joined by welding or the like to be integrated. Note that a nut fastening hole 14 is cut out in the outer cylinder 3-3, and a nut can be rotated by inserting a tool from the nut fastening hole 14.

FIG. 4 is a side view of the bolt fastening device, showing another example of a structure for rotating a nut. FIG. 4 (a) is a side view, and FIG. 4 (b) is a sectional view taken along line EE in FIG. is there.
In both figures, tool insertion holes 15 are machined up and down at four places around the outer periphery of the inner cylinder 3 and are evenly arranged on the circumference. Four tool insertion holes 16 having the same diameter as the hole 15 and located at the same position as the hole 15 are provided.

Four tools (not shown) are inserted into the four tool insertion holes 15 from above, and the inner cylinder 3 is rotated into the tool insertion holes 16 of the nut 2 to perform positioning. Insert the tool into the tool insertion hole 16, and insert the nut 2
Can be turned to tighten or loosen the nut. As another method of rotating the nut 2, a rotation tool can be inserted from the nut fastening hole 14 described with reference to FIG. 3 to rotate the nut.

FIG. 5 is a cross-sectional view of the bolt 1 after the tightening is completed by applying the large-sized bolt fastening device of the present embodiment and the bolt fastening device is removed as described later. FIG. 6 is a diagram showing the relationship between the bolt 1, the inner cylinder 3, and the outer diameter of the outer cylinder 4 of the present large-sized bolt fastening device. In the figure, the gap between the inner cylinder 3 and the outer cylinder 4 is ignored. Is shown.

In FIG. 6, if the area of the bolt 1 is S ₁ , the area of the inner cylinder 3 is S ₂ , and the area of the outer cylinder 4 is S ₃ , the tensile stress applied to the bolt 1 is outside the inner cylinder 3. Since it is transmitted to the cylinder 4 and received, it must be S ₁ = S ₂ = S ₃ . Therefore, according to this relationship, the outer diameter of the bolt 1 is D
Then, the outer diameter of the inner cylinder 3 is と な り (2D) and the outer diameter of the outer cylinder 4 is √ (3D), and a large bolt fastening device is designed in such a relationship. In a practical example of the bolt 1, for example, in the case of a steam turbine, a bolt having a diameter of D = about 150 mm is used.

FIG. 7 is a system diagram of the medium of the large bolt fastening device described above. In FIG. 7, reference numeral 30 denotes an apparatus for generating steam by a steam generator,
1, comprising a pump 32, an evaporator 33, and an electric heater 33a in the evaporator 33, using water as a medium, and heating water from the drain tank 31 with the electric heater 33a to produce steam of 100 ° C. or more. Is generated and sent to a large bolt fastening device as described later.

A cooling device 40 uses Freon as a medium, and comprises a drain pot 41, a condenser 42 rotated by a motor 43 to radiate heat from the medium, and a compressor 43. The condenser 43 converts the Freon from the drain pot 41 into a condenser. 4
2. Cool to 0 ° C. or less by the compressor 43 and send out the cooled chlorofluorocarbon to a large bolt fastening device as described later.

Reference numerals 20-1 and 20-2 denote on-off valves, which are provided with steam heated to 100 ° C. or higher at the medium supply port 11a of the inner cylinder 3;
21-1 and 21-2 are also on-off valves for sending CFCs cooled to or below 0 ° C., respectively.
In the following, the cooled chlorofluorocarbon is sent out to flow into the medium supply passage, the medium hole, and the circular passage of the inner cylinder 3 and the outer cylinder 4.

22-1, 22-2, 23-1, 23-2
The on-off valves 22-1 and 22-2 collect Freon heated by cooling the inner cylinder 3 from the medium recovery port 11b of the inner cylinder 3 and steam cooled by heating the inner cylinder 3 respectively. The opening / closing valves 23-1 and 23-2 cool the outer cylinder 4 from the medium recovery port 13b of the outer cylinder 4, heat the heated Freon and the outer cylinder 4, and drain the cooled steam respectively. 4
1. For collection in the drain tank 31.

Next, the bolt fastening operation of the large bolt fastening device having the above-described structure will be described with reference to FIGS. First, as shown in FIG. 7, the bolt 1 is set in the hole of the workpiece 50, and the nut 2 is turned to tighten. Thereafter, the outer cylinder 4 is passed through the tip of the bolt 1, and the inner cylinder 3 is further inserted between the tip of the bolt 1 and the outer cylinder 4, and the inner cylinder 3 is screwed and set to the threaded portion 1 a at the tip of the bolt 1.

Next, the medium supply port 11A and the recovery port 1 of the inner cylinder 3
1b, the medium supply port 13a and the recovery port 13b of the outer cylinder 4 are respectively connected to the medium system, and the setting is completed. Note that 11
Since the systems connected to a and 11b rotate together with the inner cylinder 3, connection to those systems uses a flexible hose or the like so that the inner cylinder 3 can rotate.

When tightening the bolts in this state, first, the on-off valves 21-1 and 23-2 are opened, and the on-off valves 21-2 and 23-1 are opened.
Is closed, a steam of 100 ° C. or more is passed between the medium supply passage 13, the plurality of medium holes 12 a, and the circular passage 12 b from the medium supply port 13 a, and the steam is caused to flow out of the medium recovery port 13 b for a predetermined time, so that the outer cylinder is closed. 4 is heated with the heat of steam. If the iron outer cylinder 4 has a difference of about 100 ° C from the surrounding temperature, about 1.
Since an elongation of about 3/1000 mm occurs, further elongation can be generated by flowing high-temperature steam. At the same time, 20-2 and 22-1 are opened and 20-1 and 22-1 are opened.
-2 is closed and cold Freon is supplied to the medium supply port 11 in the inner cylinder 3.
a to the medium supply passage 10, the cooling hole 10a, and the circular passage 12b to cool the inner cylinder 3 in the same manner.

After the outer cylinder 4 has been heated for a predetermined time and the inner cylinder 3 has been cooled, the outer cylinder 4 extends as described above, so that the outer cylinder 4 extends through the inner cylinder flange 3a of the inner cylinder 3 by that amount. The bolt 1 screwed to the tube 3 is pulled upward, and the bolt 1 is extended by the pulling force. When the bolt 1 is extended, a gap is formed between the nut 2 and the workpiece 50. This state is shown in FIG. In FIG. 8, when (a) is in a normal temperature state, (b) heats the outer cylinder 4 with steam at 100 ° C. or higher, cools the inner cylinder 3 with chlorofluorocarbon at 0 ° C. or lower. There occurs a thermal expansion, and shows a state where the inner cylinder flange is extended by L _1.

FIG. 8 (c) shows the release valves 21-2, 23-
Open the outer cylinder 4 with fluorocarbon
Is cooled to 0 ° C or less, and at the same time, the opening valves 20-1, 22-
2 is opened, 20-2 and 22-1 are closed, the inner cylinder 3 is similarly heated with steam, the nut 2 is further pulled upward by the contracting force of the inner cylinder 3, and the nut is tightened by the generated gap. Is shown.

In this case, the rotation of the nut 2 is performed by inserting a tool from the nut fastening hole 14 shown in FIG. 3 or by inserting a tool from the tool insertion hole 15 of the inner cylinder 3 as shown in FIG. A tool can be inserted into and engaged with a tool insertion hole 16 provided in the nut 2 and the nut 2 can be rotated together with the inner cylinder 3 to tighten the nut.

Such heating of the outer cylinder 4 by steam and cooling of the inner cylinder 3 by Freon and cooling of the outer cylinder 4 by Freon and heating of the inner cylinder 3 by steam are alternately repeated several times. Applying force to nut 2 and workpiece 5
A gap is formed between the bolt and the bolt, and the nut 2 is rotated to gradually increase the bolt tightening force, so that the bolt can be fastened with the required strength. It should be noted that the elongation of the bolt is to extend the bolt by about 0.1 to 0.15% of the total length and tighten the bolt. The tensile stress of the bolt due to thermal elongation is about 30 kg / mm ² .

In this embodiment, steam is used as the heating medium, and chlorofluorocarbon is used as the cooling medium. The steam temperature is 100 ° C. or higher, and high-temperature steam is used. Other than the above, high-temperature air can be used, and low-temperature air can be used as a cooling medium. The temperature of the cooling water is in the range of 5 ° C. to -10 ° C., and the water temperature is such that the temperature does not freeze. In addition,
When water below 0 ° C is used, it is preferable to use antifreeze. As the heating source, the example of the electric heater 33a has been described in the above embodiment, but other heaters,
Boilers and the like can also be used.

When the fastening of the bolt 1 is completed, the pipes of the respective steam supply source and the Freon supply source are removed, the inner cylinder 3 is rotated and removed from the bolt 1, and the operation is completed when the outer cylinder 4 is removed. This state is shown in FIG.

According to the embodiment described above, the inner cylinder 3 and the outer cylinder 4 are combined, the outer cylinder 4 is heated by steam, cooled by Freon, the outer cylinder 4 is further cooled, and the inner cylinder 3 is cooled. The bolts 1 are stretched by applying a tensile force to the bolts 1 and the nuts 2 are tightened by heating the bolts 1 so that the nuts 2 are tightened. In addition, the bolts can be fastened using the cooling device 40, and a large-scale installation of a heating device, a cooling device, and the like is not required. Further, since the tightening and removal of the large bolts are simplified, the cost of assembling and disassembling the machine such as the turbine casing is reduced.

[0044]

According to the present invention, there is provided a large-sized bolt fastening device comprising:
An inner cylinder that has a flange around the distal end and is screwed to a screw portion of a bolt that engages with a nut that fastens the object to be fastened; and that the outer circumference of the inner cylinder and the nut is covered with a predetermined gap, and the cylindrical shape is formed. A medium passage communicating with the inside of a wall around the inner cylinder is formed of an outer cylinder arranged such that the tip of the outer cylinder abuts against the lower surface of the flange of the inner cylinder and the lower end is supported by the workpiece. A medium passage communicating with the inside of the wall around the cylinder is provided,
Further, a basic feature is that a tool hole for rotating the nut is provided in either the inner cylinder or the outer cylinder. With such a configuration, simple steam generators and cooling devices are installed, and large-scale heating equipment and hydraulic devices are installed using existing steam generation sources and cooling water systems installed in the factory. It is possible to fasten large bolts without any trouble, and because of the simple structure, assembly and disassembly of the turbine casing and machinery by tightening and removing the bolts can be easily performed, which can contribute to cost reduction.

A second aspect of the present invention is characterized in that, in the first aspect of the present invention, the inner cylinder and the outer cylinder are assembled by combining a plurality of divided portions, respectively. When drilling by connecting the cooling water passage and the steam passage inside the inner cylinder and the outer cylinder, holes and grooves are formed in the divided parts, and these divided parts are combined to form the inner cylinder and the outer cylinder. Processing of the passage inside becomes easy.

According to a third aspect of the present invention, in the first aspect of the present invention, the tool hole is formed by cutting out a part of the lower end of the outer cylinder. It is characterized by a notch that penetrates toward the lower part and cuts the peripheral surface vertically.The tool insertion for rotating the nut is performed by drilling holes in the outer cylinder or inner cylinder. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a large bolt fastening device according to one embodiment of the present invention.

2 (a) is a side view, FIG. 2 (b) is a sectional view taken along the line AA in FIG. 2 (a), and FIG. 2 (c) is a sectional view of the internal bolt of the large bolt fastening device according to the embodiment of the present invention. It is B sectional drawing.

3A and 3B show an outer cylinder of a large bolt fastening device according to an embodiment of the present invention, wherein FIG. 3A is a side view, FIG. 3B is a cross-sectional view taken along the line CC in FIG. 3A, and FIG. It is D sectional drawing.

4A and 4B show a large bolt fastening device according to an embodiment of the present invention, wherein FIG. 4A is a side view showing a tool insertion hole, and FIG.
FIG. 3 is a cross-sectional view taken along the line EE in FIG.

FIG. 5 is a cross-sectional view of the large bolt according to the embodiment of the present invention after fastening.

FIG. 6 is a diagram showing an outer diameter of a large-sized bolt fastening device according to an embodiment of the present invention.

FIG. 7 is a system diagram of a medium of the large-sized bolt fastening device according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a thermal expansion difference between an inner cylinder and an outer cylinder of the large-sized bolt fastening device according to one embodiment of the present invention. , When the inner cylinder is cooled,
(C) shows a case where the outer cylinder is cooled and the inner cylinder is heated.

FIG. 9 is a longitudinal sectional view of a conventional large-sized bolt fastening device using mechanical tension.

FIG. 10 is a longitudinal sectional view of a conventional large-sized bolt fastening device using a heating method.

[Explanation of symbols]

 Reference Signs List 1 bolt 2 nut 3 inner cylinder 3a inner cylinder flange 4 outer cylinder 10 medium supply passage 10a medium hole 10b, 12b circular passage 11a medium supply port 11b medium collection port 12 medium supply path 12a medium hole 13a medium supply port 13b medium collection Port 14 Nut fastening hole 15, 16 Tool insertion hole 20-1, 20-2 On-off valve 21-1, 21-2 On-off valve 22-1, 22-2 On-off valve 23-1, 23-2 On-off valve 30 Steam generator 31 Drain tank 32 Pump 33 Evaporator 33a Electric heater 40 Cooling device 41 Drain pot 42 Condenser 43 Compressor 50 Work piece

Claims (4)

[Claims] An inner cylinder which has a flange around the tip and is screwed to a screw portion of a bolt which engages with a nut for fastening an object to be fastened, and a predetermined gap is maintained between the inner cylinder and the outer periphery of the nut. A medium passage communicating with the inside of a wall surrounding the inner cylinder, the outer cylinder being arranged so as to cover and have a cylindrical tip abutting against a lower surface of the flange of the inner cylinder and a lower end supported by the object to be fastened; A medium passage communicating with the inside of a wall around the outer cylinder, and a tool hole for rotating the nut in either the inner cylinder or the outer cylinder. apparatus. 2. The large bolt fastening device according to claim 1, wherein the inner cylinder and the outer cylinder are assembled by combining a plurality of divided portions. 3. The large-sized bolt fastening device according to claim 1, wherein the tool hole is formed by cutting off a part of a lower end of the outer cylinder. 4. The large-sized tool according to claim 1, wherein the tool hole is formed by a notch that penetrates an upper flange of the inner cylinder toward a lower portion and cuts a circumferential surface of the inner cylinder vertically. Bolt fastening device.