JPS6220641Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Technical field of invention] The present invention relates to a turbine rotor.

[Technical background of the invention] In general, low-pressure rotors of large steam turbines for power generation use long blades with a large average diameter in order to flow a large amount of steam.

In such a huge turbine rotor,
In order to solve manufacturing technical and economical problems, a so-called shrink-fit wheel has been adopted, in which the wheel into which the blades of each stage are implanted is manufactured separately from the shaft, and then the wheel is heated before being fitted onto the rotor shaft. .

FIG. 1 shows a steam turbine rotor with such a shrink-fitted wheel, designated by the reference numeral 1 in the figure.
indicates the shaft of the turbine rotor. A plurality of shrink-fit wheels 3 having blades 2 on the outer periphery are fitted onto the shaft 1 by wheel bore keys 4 along the axial direction of the shaft 1 .

Further, a locking key 5 is provided to restrict movement of the wheel 3 in the axial direction.

In the turbine rotor configured in this way, steam energy is converted into torque by the blades 2 and then transmitted to the wheel 3. Torque is transmitted from the wheel 3 to the shaft 1 by shrink fitting the wheel 3. This is done by the friction force due to the surface pressure of the surface and the wheel bore key 4.

In other words, in such a turbine rotor, in a stage where the pressure and temperature are relatively high near the steam inlet side, the wheel 3, which has a small heat capacity, is heated faster than the shaft 1 due to the operating conditions, creating a temperature difference between the wheel 3 and the shaft 1. It may come loose, and in the unlikely event that
When the wheel 3 becomes loose, torque is transmitted by the wheel bore key 4. Note that the shrink-fit surface on the inner surface of the wheel 3 maintains a constant surface pressure with the shaft 1 and maintains a uniform stress in the tangential direction of the inner surface.

[Problems with background technology]

However, in the turbine rotor configured in this way, a wheel bore key groove 6 is provided on the inner surface of the wheel 3 in order to fit the wheel bore key 4, and stress is generated around the wheel bore key groove 6. As shown in FIG. 2, stress corrosion cracks 7 occur around the wheel bore keyway 6.
(SCC) may occur. Especially about 130 ~
Wheel 3 is exposed to an atmosphere of 150°C, and wheel 3 becomes a high stress field, causing wheel bore keyway 6 to
There is a risk that stress corrosion cracking 7 will occur.

If the turbine continues to operate with such cracks generated, the cracks will gradually develop and grow, and at a certain point a sudden breakage phenomenon will occur.

Therefore, there has been a demand for a turbine rotor having a function of reliably detecting stress corrosion cracking occurring in the key groove portion formed in the wheel 3.

[Purpose of the invention] The present invention was developed in response to the above-mentioned conventional circumstances, and is equipped with a function that can quickly and reliably detect stress corrosion cracking that occurs in the key groove formed in the wheel as necessary. It is intended to provide a turbine rotor.

[Summary of the invention] In other words, the present invention has a wheel with key grooves formed on the side surface of the hub portion, and is fitted along the axial direction of a plurality of shafts, and keys are attached to the key grooves to connect them to each other. In the turbine rotor, key grooves provided on the side surfaces of the hub of the wheel are provided at a certain angle between both side surfaces of the hub part, and ultrasonic flaw detector installation grooves are arranged back to back with these key grooves. This is a characteristic turbine rotor.

[Embodiment of the invention] The details of the invention will be described below with reference to an embodiment shown in the drawings.

FIG. 3 shows a turbine rotor according to an embodiment of the present invention, and in the figure, reference numeral 1 indicates the shaft of the turbine rotor. A plurality of wheels 3 having blades 2 implanted on the outer peripheral surface are fitted onto the shaft 1 along the axial direction. and a wheel 3 located upstream of the turbine rotor.
are connected to each other by a connecting member consisting of, for example, a wheel radial key 8, which transmits torque to each adjacent wheel 3.

The wheel 3a disposed on the downstream side of the steam inlet of the turbine rotor has a wheel bore key groove 6 formed therein as in the conventional case, and the wheel bore key 4 is inserted into the wheel bore key groove 6.

FIG. 4 shows an enlarged view of the wheel 3 shown in FIG. 3, and in the figure, reference numeral 3 indicates the wheel. Each side of the hub part 9 of the wheel 3 has
Wheel radial keyways 10a and 10b are formed in the radial direction at an angle of 180 degrees, and an annular annular groove 11 is formed in contact with the lower and upper ends of the wheel radial keyways 10a and 10b. . Wheel radial keyway 10 of wheel 3
A rectangular wheel radial key 8 is inserted into a and 10b, and a protrusion 12 formed at one end of this wheel radial key 8 is inserted into an annular groove 11, and the wheel radial key 8 is rotated by rotation of the turbine rotor. This prevents it from coming off due to centrifugal force.

The position of the wheel radial keyway 10a formed on one side of the wheel 3 is shifted by 90 degrees in the circumferential direction with respect to the position of the wheel radial keyway 10b formed on the opposite side of the wheel 3. It is arranged. The wheel radial key grooves 10a, 10 are formed on the opposite surface of the wheel 3 where the wheel radial key grooves 10a, 10b are formed.
This wheel radial keyway 10 is opposite to b.
Ultrasonic flaw detector installation grooves 13a and 13b are formed wider than a and 10b.

5 and 6 show the state in which the ultrasonic flaw detector 14 is installed in the ultrasonic flaw detector installation grooves 13a, 13b. The ultrasonic flaw detector is shown fixed to the

In the turbine rotor configured in this way, as shown in FIGS. 5 and 6, the ultrasonic flaw detector 1
By emitting ultrasonic waves from 4 toward the wheel radial keyway 10a or 10b of the wheel 3 as shown by the broken line in the figure, stress corrosion cracking 7 occurring near the wheel radial keyway 10a or 10b can be easily detected. can do.

In the turbine rotor configured as described above, torque from the wheel 3 is transmitted to the shaft 1 by the frictional force due to the surface pressure of the shrink fit surface of the wheel 3 during normal operation of the turbine rotor.

On the other hand, wheel 3 with a small heat capacity is connected to shaft 1.
If the wheel 3 on the steam inlet side is heated faster and loosens, the torque applied to the loosened wheel 3 is transmitted to the shaft 1 via the adjacent wheel 3. For example, when all of the wheels 3 on the upstream side become loose and torque cannot be transmitted to the shaft 1, the torque is transmitted through the wheel 3 disposed at the most downstream position and locked to the shaft 1 by the wheel bore key 4. is transmitted to shaft 1.

That is, in the turbine rotor configured in this way, the wheel bore keyway 6 formed on the inner circumferential surface of the wheel 3 disposed on the steam inflow side can be removed, so that it is possible to remove the wheel bore keyway 6 formed on the inner circumferential surface of the wheel 3 disposed on the steam inflow side. It is possible to eliminate stress corrosion cracking 7.

In addition, in such a turbine rotor, a wheel radial keyway 1 is provided on the side surface of the hub portion 9 of the wheel 3.
However, since the stress level in this portion is relatively low, there is relatively little risk of stress corrosion cracking 7 occurring in this wheel radial keyway 10.

In addition, the wheel 3a located at the most downstream position among the wheels 3 is connected to the shaft 1 by the wheel bore key 4.
However, the wheel 3a at this portion has a relatively low risk of stress corrosion cracking even if stress concentration occurs as described above, so a structure similar to the conventional one is sufficient.

[Effects of the Invention] As described above, according to the turbine rotor of the present invention, stress corrosion cracking occurring in the keyway can be detected quickly and reliably, and a highly reliable turbine rotor can be provided.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing a conventional turbine rotor, Fig. 2 is a longitudinal sectional view showing stress corrosion cracking occurring in the key portion, and Fig. 3 is a longitudinal sectional view showing a turbine rotor according to an embodiment of the present invention. , FIG. 4 is an enlarged perspective view of the wheel shown in FIG. 3, FIG. 5 is a vertical sectional view of the turbine rotor showing the ultrasonic flaw detector installed in the ultrasonic flaw detector installation groove, and FIG. is − in Figure 5.
It is an arrow view. 1...Shaft, 2...Blade, 3...Wheel, 8...Wheel radial key, 10a, 10
b...Wheel radial keyway, 13a, 13b
...Ultrasonic flaw detector installation groove, 14...Ultrasonic flaw detector.

Claims (1)

[Claims for Utility Model Registration] (1) A plurality of wheels each having a keyway bored in the side surface of the hub portion are fitted along the axial direction of the shaft, and a key is attached to the keyway to connect them to each other. In the turbine rotor, key grooves provided on the side surfaces of the hub portion of the wheel are provided at a certain angle shifted between both side surfaces of the hub portion, and ultrasonic flaw detector installation grooves are arranged back to back with these key grooves. A turbine rotor characterized by: (2) The turbine rotor according to claim 1, wherein the keyways are arranged at different angles of 90 degrees in the circumferential direction from one position between both side surfaces of the hub portion.