JPS6316563B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to turbine rotors.

[Technical Background of the Invention] Generally, in low-pressure rotors of large steam turbines for power generation, etc., long blades with a large average diameter are used 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, and the torque is transmitted from the wheel 3 to the shaft 1 through the shrink-fit surface of the wheel 3. This is done by the friction force due to the surface pressure 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
If 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 Art] However, in the turbine rotor configured in this manner, 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 this wheel bore key Stress concentrates around the groove 6, and as shown in Figure 2, stress corrosion cracking 7 (SCC) occurs around the wheel bore keyway 6.
may occur. In particular, when the wheel 3 is exposed to an atmosphere of about 130 to 150° C., the wheel 3 becomes a high stress field, and stress corrosion cracking 7 may occur in the wheel bore keyway 6.

[Object of the Invention] The present invention has been made in response to such conventional circumstances, and it is possible to eliminate the risk of stress corrosion cracking occurring in the wheel bore key groove of a wheel, and to improve torque transmission between the wheel and the shaft. The purpose is to provide a turbine rotor that can be used reliably.

[Summary of the Invention] That is, the present invention provides a turbine rotor in which a wheel having blades is fitted in a single stage or in multiple stages along the axial direction of a shaft, which is inserted into the shaft adjacent to the wheel and is connected to the wheel. a torque ring having a plurality of locking protrusions on a contact surface;
A plurality of locking grooves formed on the wheel to engage with the locking convex portion of the torque ring, a plurality of keyways provided on the inner peripheral surface of the torque ring, and a plurality of locking grooves corresponding to the keyways. a second keyway provided on the outer peripheral surface of the shaft; and a key inserted between the second keyway and the first keyway, and an engagement portion between the wheel and the torque ring; The turbine rotor is characterized in that it is configured to transmit the rotational torque of the wheel to the shaft via the torque ring and the key portion of the shaft.

[Embodiment of the Invention] The details of the present 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 each arranged adjacent to the wheel 3 and are connected by a connecting means to a torque ring 8 that transmits torque to the shaft 1.

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

4 and 5 are enlarged views of the wheel 3 and torque ring 8 shown in FIG. 3, and in the figures, reference numeral 3 indicates the wheel. wheel 3
Two wheel keyways 9 are formed at 180 degrees along the circumferential direction on the side surface of the wheel. A cylindrical torque ring 8 on which the shaft 1 is fitted is disposed adjacent to the wheel 3, and the side surface of the torque ring 8 is formed integrally with the torque ring 8 and has the aforementioned wheel key groove of the wheel 3. A torque ring key 10 to be inserted into 9 is formed. Two torque ring bore key grooves 11 are formed on the inner peripheral surface of the torque ring 8 at an angle of 180 degrees.

This torque ring bore keyway 11 of shaft 1
A keyway 12 is formed at a position corresponding to , and a torque ring bore key 13 is inserted into the space formed by this keyway 12 and the torque ring bore keyway 11 described above. In the figure, reference numeral 5 indicates a locking key.

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

On the other hand, wheel 3 with a small heat capacity is connected to shaft 1.
When the wheel 3 is heated faster and becomes loose, the torque of the wheel 3 is transmitted to the torque ring bore key 13 via the torque ring key 10 formed integrally with the torque ring 8, and the torque ring bore key 13 is It is transmitted to the shaft 1 via.

However, in the turbine rotor configured in this way, the torque ring 8 has a smaller outer diameter and weight than the wheel 3, so the action of centrifugal force during operation is very small, and the shrink-fit surface of the torque ring 8 Surface pressure can be made very small.

Therefore, the stress in the tangential direction of the inner surface of the torque ring 8 becomes extremely small, the stress concentration occurring in the torque ring bore keyway 11 becomes small, and there is no risk of stress corrosion cracking occurring in the torque ring bore keyway 11. .

In addition, in the turbine rotor configured as described above, since the torque ring key 10 is integrally processed with the torque ring 8, there is no need to provide a key groove for the torque ring key 10 in the torque ring 8, and the number of parts is reduced. , it is possible to solve problems such as stress concentration occurring in the key groove portion.

Incidentally, the axial positioning of the wheel 3 with respect to the stationary blade can be easily performed by managing the gap between the torque ring 8 and the wheel 3 using, for example, a spacer.

[Effects of the Invention] As described above, according to the turbine rotor of the present invention, it is possible to completely eliminate stress corrosion cracking that has conventionally occurred in the keyway formed on the inner circumferential surface of the wheel, and also to improve the relationship between the wheel and the wheel. Torque can be reliably transmitted to the shaft.

[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 part, 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 vertical sectional view showing the wheel and torque ring of FIG. 3, and FIG. 5 is a perspective view of FIG. 4. 1...Shaft, 2...Blade, 3...Wheel, 8...Torque ring, 9...Wheel keyway, 10...Torque ring key, 13...Torque ring bore key.

Claims (1)

[Scope of Claims] 1. A turbine rotor in which a wheel having blades is fitted in a single stage or in multiple stages along the axial direction of a shaft, the rotor being inserted through the shaft adjacent to the wheel,
A torque ring having a plurality of locking protrusions on a contact surface with a wheel, a plurality of locking grooves formed in the wheel so as to engage with the locking protrusions of the torque ring, and the torque ring. a plurality of key grooves provided on the inner circumferential surface of the shaft; a second key groove provided on the outer circumferential surface of the shaft corresponding to the key groove; and a space between the second key groove and the first key groove. and an inserted key, and is configured to transmit rotational torque of the wheel to the shaft via an engaging portion between the wheel and the torque ring, and a key portion between the torque ring and the shaft. turbine rotor.