JPH0579302A - Joint of turbine casing and joint auxiliary device - Google Patents

Abstract

PURPOSE:To shorten a maintenance working period by carrying out bolt extension at the time of additional tightening in the fastening process of a turbine casing bolt under a hydraulic method but not under a bolt heater method requiring temperature control. CONSTITUTION:A device consisting of a tension nut 17 of a T type sectional shape screwed on the head part of a bolt 12 to be fastened, a cylinder 18 hydraulically actuated to push up this tension nut 17 is used. A support part of reaction to work at the time of pushing up the tension nut 17 by a piston 19 for bolt extension is to be taken on the head parts of both of neighbouring bolts 12a, 12b adjacent to the bolt 12 to be fastened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fastening a turbine casing, and more particularly, to tightening a bolt mounted on a flange of a steam turbine casing, and can be applied to general flange structures requiring bolt tightening.

[0002]

2. Description of the Related Art A conventional method for fastening a steam turbine casing will be described with reference to FIGS. Although not shown, the turbine casing is generally composed of an upper half and a lower half of the casing divided into upper and lower halves, and flanges 1 and 2 are provided in the upper half and the lower half of the casing, respectively. Is provided. The turbine casing is formed by aligning the upper half of the casing and the lower half of the casing and fastening these flanges 1 and 2. For fastening the flanges 1 and 2, for example, in the illustrated example, a bolt 4 is screwed into the flange 2 through a bolt hole 3 of the flange 1, and the head of the bolt 4 is tightened and fixed with a nut 5. For the final bolt tightening, as shown in FIG. 2, the bolt 4 is heated by the bolt heater 6 installed in its center hole to be stretched, and the nut 5 is tightened.
The bolt heater system is adopted to obtain the required tightening allowance by tightening.

The procedure of tightening the bolt will be described. First, the bolt 4 and the nut 5 are attached to the flanges 1 and 2, and 0 point setting (flange surface contact) is performed. At this time, as shown in FIG. 3, a bolt elongation measuring instrument composed of the sleeve 7, the rod 8 and the micrometer 9 measures the zero point before heating the bolt, that is, the value M in the state where the elongation is zero. That is, the sleeve 7 is supported by the step 10 provided in the bolt center hole, the rod 8 is inserted into the bolt center hole through the sleeve 7, the lower end thereof is brought into contact with the plug 11, and the sleeve 7 is moved by the micrometer 9. The value M at the time of 0 point is read by measuring the distance to the top of the.

A relational point representing the rotation angle of the nut 5 required for tightening is marked on the nut 5 and the flange 1 adjacent thereto with a chalk or the like.

The bolt elongation measuring instrument is removed from the bolt center hole (the sleeve 7 may be left), and instead, a bolt heater 6 is installed, and the bolt 4 is heated to about 0.5 H to give an elongation. , Tighten the nut 5 until the relation points match.

The bolt 4 is cooled to the same temperature as before being heated over 8 to 10 hours, and the value M ₁ after heating is read again by the micrometer 9 of the bolt elongation measuring instrument.
Now, by calculating (M−M ₁ ) the bolt 4
It is possible to know the amount of elongation and to see if the required tightening margin has been obtained.

If the necessary tightening allowance is not obtained, the steps of heating the bolt 4, tightening the nut 5, cooling the bolt 4 and measuring the elongation amount are repeated to obtain the necessary tightening allowance.

[0008]

By the way, in the conventional bolt tightening in the turbine casing, since the bolt heater system is adopted, the time required to measure the amount of bolt elongation, mainly the heating time and the cooling time, is mainly used. It takes a long time. During heating, since the inside of the bolt is directly heated, deterioration of the bolt material is promoted. In addition, the bolt heater is often burnt out, and it is difficult to store moisture in the bolt heater body because measures against moisture are required. Further, when the temperature of the turbine casing is high, the retightening using the bolt heater is impossible. An object of the present invention is to provide a fastening method for a turbine casing that solves such a problem.

[0009]

For the above object, according to the present invention, bolts and nuts are attached to the flanges provided in the upper half of the vehicle compartment and the lower half of the vehicle compartment to set the zero point. While applying reaction force to the heads of the bolts on both sides adjacent to the bolt to be tightened, apply tension to the bolt to be tightened, tighten the nut on the tensioned side, and remove the tension. A method of fastening a turbine casing is provided.

Further, according to the present invention, as a device for carrying out the above-mentioned fastening method, a tension nut having a T-shaped cross section having a leg portion capable of being screwed with the head portion of a bolt to be tightened, and this tension. There is provided a fastening assistance device for a turbine casing, which comprises a hydraulically actuated cylinder and a piston that are located between the top flange portion of the nut and the head portions of the bolts on both sides of the bolt to be tightened.

[0011]

According to the above means, after setting the 0 point of the bolt to be tightened, the cylinders having the pistons are set in the bolt heads on both sides of the bolt to be tightened,
Screw the tension nut into the bolt you want to tighten. Supply pressure oil to the cylinder, push up the tension nut to extend the bolt, and tighten it further. After depressurizing the cylinder, measure the amount of elongation and confirm the required tightening allowance.

[0012]

1 is a cross-sectional view illustrating a preferred embodiment of the present invention, in which the same elements as those shown in FIGS. 2 and 3 are designated by the same reference numerals. The present invention is particularly suitable for application in a case where the bolt pitch is very narrow, such as in a high-pressure turbine casing, and there is almost no gap between nuts that tighten adjacent bolts.

Bolt holes 3 are formed in the flanges 1 and 2 provided in the upper half of the vehicle compartment and the lower half of the vehicle compartment in alignment with each other, and both nut bolts 12 are inserted into the bolt holes 3. The nut 14 is screwed into the upper part of the plug via the spherical washer 13, and the plug 11 is screwed into the lower part of the lower part.
A nut 16 is screwed in via a flat washer 15. In addition, 12a and 12b are both nut bolts on both sides adjacent to both nut bolts 12, and 14a and 14b are nuts of these both nut bolts 12a and 12b.

At the top of FIG. 1, a bolt tensioner used as an auxiliary device when fastening the turbine casing is shown. This bolt tensioner has a tension nut 1
7, a cylinder 18, and a piston 19, the tension nut 17 has a T-shaped cross section, and the leg 20 has an inner surface threaded so that the heads of both nut bolts 12 can be screwed. Has a bolt hole, and a measuring hole for communicating with the bolt hole and for installing a bolt elongation measuring instrument is provided on the rotation center axis line.

An annular cylinder 18 and an annular piston 19 fitted in the cylinder 18 are located between the flange portion 21 at the top of the tension nut 17 and the head portions of both nut bolts 12a and 12b. A hose from an electric hydraulic pump that supplies pressure oil into the cylinder is connected to the oil inlet 22 of the cylinder 18. A hydraulic pressure gauge is attached to the hydraulic system between the electric hydraulic pump and the cylinder 18. Grooves are provided on the outer circumference and the inner circumference of the piston 19, and O-rings 23 and 24 for keeping airtightness with the inner wall of the cylinder 18 are fitted therein.

A method of tightening bolts using such a bolt tensioner will be described. First, both nut bolts 12 and nuts 14 and 16 are attached to the flanges 1 and 2, and the zero point is set, that is, the measurement when the amount of bolt extension is 0 is performed. Next, attach the piston 1 to the heads of both nut bolts 12a and 12b on both sides of both nut bolts 12 to be tightened.
9 is installed, and the tension nut 17 is screwed into both nut bolts 12 to be tightened (state of FIG. 1). Next, the hose from the electric hydraulic pump is connected to the oil inlet 22 of the cylinder 18. When the pressure oil from the electric hydraulic pump is supplied to the cylinder 18 to increase the pressure, the piston 19 pushes up the tension nut 17,
Both nut bolts 12 connected to this are pulled up.
At this time, the support portion for the reaction force is the nut bolts 12 for tightening.
It will be taken on the bolt head on both sides of. When both nut bolts 12 have been extended, the nut 14 is manually tightened and then the pressure oil is reduced by stopping the electric hydraulic pump or the like, and then the amount of bolt extension is measured.

[0017]

According to the present invention, the tension nut for extending the nut to be tightened has a T-shaped cross section,
Since the reaction force support parts were on the heads of the bolts on both sides, the bolt pitch was narrow and the reaction force support parts could not be taken on the flange surface of the passenger compartment. Therefore, tightening with a device using hydraulic pressure was not considered. Applicable to turbine casing bolts.

Further, according to the present invention, by controlling the hydraulic pressure, the required bolts can be tightened, and the bolts can be easily tightened even when the turbine casing is hot, and the structure of the bolt tensioner is simple and can be stored. Since it is simple, maintenance at the time of regular inspection is easy and the process can be shortened significantly.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a structure around a bolt to be tightened in the present invention.

FIG. 2 is a sectional view of an essential part showing a state of mounting and assembling a bolt heater which is a conventional bolt extending means.

FIG. 3 is a cross-sectional view of essential parts showing a state of mounting and assembling a bolt elongation measuring instrument.

[Explanation of symbols]

 1, 2 Flange 12 Both nut bolts 14, 16 Nut 17 Tension nut 18 Cylinder 19 Piston 20 Leg part 21 Collar part 22 Oil injection port 23, 24 O-ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Takita 1-1 1-1 Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Yutaka Nagata 1-1 1-1 Atsunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industry Co., Ltd.Nagasaki Shipyard

Claims (2)

[Claims] 1. Heads of bolts on both sides adjacent to the bolt to be tightened by attaching bolts and nuts to flanges provided on the upper half of the passenger compartment and the lower half of the passenger compartment to set 0 points. A fastening method for a turbine casing, in which a tension is applied to a bolt to be tightened while a reaction force is applied to the bolt, a nut on the tensioned side is tightened, and the tension is removed. 2. A tension nut having a T-shaped cross section having a leg portion that can be screwed into the head of a bolt to be tightened, a top flange portion of the tension nut, and bolts on both sides of the bolt to be tightened. A fastening assistance device for a turbine casing, which is formed between a head portion and a hydraulically actuated cylinder and a piston.