JPS59136501A - Turbine rotor - Google Patents

Abstract

PURPOSE:To reduce the temperature difference between a wheel and a shaft, and prevent the wheel from loosening by a method wherein the most upstream wheel among plural wheels which are engaged with a rotor shaft is arranged separating from immediate adjacent downstream side wheel. CONSTITUTION:A wheel 3a located at the most upstream side is arranged with certain large gap between immediate adjacent downstream side wheel 3b in a turbine rotor wherein plural wheels 3 are fitted in the direction of a shaft which are planted with blades 2 on the outer peripheral surface thereof. The wheels 3 located at the downstream side of the wheel 3b are continuously arranged keeping usual very small gap, while those wheels 3 are respectively connected with connecting member such as wheel radial keys 8 and the like. Further, wheel key grooves 6 are formed on wheels 3c arranged at the downstream side of a steam flow inlet. A wheel bore keys 4 are inserted into the key grooves 6.

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.

For such a huge Ebin rotor, in order to solve manufacturing technology and economic problems, the wheel into which the blades of each stage are implanted is manufactured separately from the shaft, and then the wheel is heated and then fitted onto the rotor shaft. A so-called shrink-fit wheel is used.

FIG. 1 shows a steam turbine rotor having such a shrink-fitted wheel, in which reference numeral 1 designates the shaft of the turbine rotor. A shrink-fitted wheel 3 having blades 2 on the outer periphery is attached to the shaft 1 as a boiler bore key 4.
A plurality of them are fitted 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, the steam energy is converted into torque by the blades 2 and then transmitted to the wheel 3, and from this wheel 3 to the shaft 1.
Torque is transmitted to the wheel by the frictional force caused by the blood pressure on the shrink-fitted surface of the wheel 3 and by the wheel bore key 4.

That is, 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, and the temperature difference with the shaft 1 is increased. This may cause the wheel 3 to become loose, and in the event that the wheel 3 becomes loose, torque will be transmitted by the wheel bore key 4. Note that the shrink-fitting surface on the inner surface of the wheel 3 maintains a constant surface pressure with the shaft 1 and also maintains 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 is concentrated around the groove 6, and as shown in Figure 2, the wheel 3 becomes a high stress field around the wheel bore keyway 6 due to stress corrosion cracking (SCC). , wheel bore keyway 6
There is a risk that stress corrosion cracking 7 will occur.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
This eliminates the temperature difference between the wheel and the shaft, prevents the wheel from loosening from the shaft, ensures reliable torque transmission between the wheel and the shaft, and prevents stress corrosion cracking that occurs in the wheel bore keyway of the wheel. It is an object of the present invention to provide a turbine rotor that can eliminate such risks.

[Summary of the Invention] The present invention provides a turbine rotor in which a plurality of wheels having blades are fitted along the axial direction of a shaft. The wheels are individually arranged in order from the most upstream side to the wheels arranged adjacent to the downstream side so that the outer surface of the shaft is exposed, and one or more stages of wheels are arranged separately. A plurality of wheels are arranged adjacent to the downstream side of the wheel and are connected to each other with a minute gap, and these wheels are connected to each other from the upstream side by connecting members, and the wheel located at the most downstream position among these wheels is connected by a key. A turbine rotor, characterized in that it is locked to 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 turbine rotor. It shows the foot. A plurality of wheels 3 having blades 2 implanted on the outer circumferential surface of the shaft 1 are fitted along the axial direction. The wheel 3a located on the most upstream side (steam inlet side) of the turbine rotor is arranged with a certain large gap from the wheel 3b adjacent to it on the downstream side (steam discharge side), and the outer surface of the shaft 1 is exposed. Note that the wheels 3 located on the downstream side of the wheels 3b are disposed continuously with a small gap, similar to a conventional turbine rotor.

The wheels 3b disposed adjacent to the wheel 3a on the most upstream side of the turbine rotor are connected to each other by a connecting member, for example, a wheel radial key 8, which transmits torque to the adjacent wheel 3.

Note that a wheel key groove 6 is formed in the wheel 3c disposed on the downstream side of the steam inlet of the turbine rotor, as in the conventional case, and a wheel bore key 4 is formed in this wheel key groove 6.
is inserted.

In addition, the wheel 3 located on the most upstream side of the turbine rotor
a is a torque ring 13 that transmits torque to the shaft 1;
is connected to.

FIG. 4 shows an enlarged view of the wheel 3 shown in FIG. 3, and in the figure, the symbol @3 indicates the wheel.

Wheel radial key grooves 10 are formed in the radial direction at an angle of 180° on both sides of the hub portion 9 of the wheel 3, and an annular stress relief groove 11 is in contact with the inside of the wheel radial key groove 10. It is formed. A rectangular wheel radial key 8 is inserted into the wheel radial key groove 10 of the wheel 3.
A holding portion 12 consisting of a convex portion formed at one end of the one-wheel radial key 8 is inserted into the stress relaxation groove 11, and prevents the one-wheel radial key 8 from coming off due to centrifugal force due to rotation of the turbine rotor. The wheel radial key 8 is
The number of mounted wheels 3 is determined by the torque transmitted by the wheel 3 to which the wheels 3 are mounted. Therefore, one or more of them may be installed depending on the magnitude of the transmitted torque.

5 and 6 are enlarged views of the wheel 3a and torque ring 13 shown in FIG.
a indicates a wheel. On the side of the wheel 3a,
2 wheel keyways 1 180° apart along the circumferential direction
0 is formed.

A cylindrical torque ring 13 into which the shaft 1 is fitted is disposed adjacent to the wheel 3a, and a wheel key groove of the wheel 3 described above is formed integrally with the torque ring 13 on the side surface of the torque ring 13. A torque ring key 14 is formed to be inserted into 10. Two torque ring bore key grooves 15 are formed on the inner peripheral surface of the torque ring 13 at an angle of 180°.

A keyway 16 is formed in the shaft 1 at a position corresponding to this torque ring bore key W415, and a torque ring bore key 17 is formed in the space formed by this keyway 16 and the aforementioned torque ring bore keyway 15. It has been inserted. In the figure, reference numeral 5 indicates a locking key.

In the turbine rotor configured as described above, the torque from the wheels 3.3a, 3b, 3c is as follows during normal operation of the turbine rotor.
It is transmitted to the shaft 1 by the frictional force due to the surface pressure of the shrink-fitting surface c.

In the turbine rotor configured as described above, a large gap is provided between the wheels 3a and 3b so that the outer surface of the shaft 1 between them is directly heated, resulting in a temperature difference between the wheels 3a and 3b and the shaft 1. As a result, the conventional wheel 3 with a small heat capacity can be made smaller.
It is possible to completely prevent the situation where a and 3b were heated faster than shaft 1 and the surface of the baking liquid was loosened.

However, if the wheel 3b located on the downstream side becomes loose, the torque applied to the loosened wheel 3h is transmitted to the -C shaft 1 via the adjacent wheel 3. For example, when all of the wheels 3 on the upstream side become loose and cannot transmit torque to the shaft 1, the torque is transmitted through the wheel 3C disposed at the most downstream position and locked to the shaft 1 by the wheel bore key 4. is transmitted to shaft 1.

On the other hand, when the wheel 3a located on the most upstream side is loose/υ, the torque of the wheel 3a is transmitted to the torque ring bore key 17 via the torque ring key 14 formed integrally with the torque ring 13. Torque is transmitted to the shaft 1 via the ring bore key 17.

However, in the turbine rotor configured in this way, the torque ring 13 has a smaller outer diameter and weight than the wheel 3a, so the action of centrifugal force during operation is very small, and the shrink-fitting surface of the torque ring 13 is smaller. Surface pressure can be made very small.

Therefore, the stress in the tangential direction of the inner surface of the torque ring 13 becomes extremely small, and the stress concentration occurring in the torque ring bore key groove 15 becomes small.
There is no risk of stress corrosion cracking occurring in M15.

In addition, in the turbine rotor configured in this way, the wheel bore key groove 6 conventionally formed on the inner circumferential surface of the wheel 3a13b disposed on the steam inflow side can be removed. This will eliminate the stress corrosion cracking 7 that had occurred.

In addition, in such a turbine rotor, the wheel radial keyway 10 is formed on the side surface of the hub portion 9 of the wheel 3, but since this portion has a relatively low stress level, stress is not applied to the G wheel radial keyway 10. There is relatively little risk of corrosion cracking 7 occurring.

In addition, among the wheels 3.3a, 3b, and 3c, the wheel 3C located at the most downstream position is locked to the shaft 1 by the wheel bore key 4, but as mentioned above, stress concentration occurs in the wheel 3C in this part. Since there is relatively little risk of stress corrosion cracking occurring, the same structure as the conventional one is sufficient. Furthermore, in the turbine rotor configured in this way, it is possible to eliminate corrosion caused by steam that has conventionally occurred on the side surface of the hub portion 9 due to the wheel bore keyway 6.

In addition, wheels 3.3a, 3b, 3c and shiv')
The shrink fit allowance of G1 is determined by external forces such as centrifugal force during normal operation,
C is determined by taking into consideration differences in expansion due to temperature differences, etc. During normal operation, torque is transmitted by the frictional force between the wheels 3.3a, 3b, 3C and the shaft 1, but in the present invention, C is determined by Heat the surface of the wheels 3a, 3
Since the temperature difference between b and the shaft 1 can be reduced, it is possible to reduce the shrink-fitting allowance which is the elongation difference due to the temperature difference. As a result, the blood pressure and tangential force on the inner surfaces of the wheels 3a and 3b can be reduced.

[Effects of the Invention] As described above, according to the turbine rotor of the present invention, the temperature difference between the wheel and the shaft is eliminated, the loosening of the wheel from the shaft is prevented, and the torque is reliably transmitted between the wheel and the shaft. In addition, it is possible to provide a highly reliable turbine rotor that can eliminate the risk of stress corrosion cracking occurring in the wheel bore keyway of the wheel.

In addition, in the embodiment described above, the most upstream wheel 3a
Although C describes an example in which the wheels 3a and 3b are made into a single stage and the outer surface of the shaft 1 is exposed by widening the gap between the wheels 3a and 3b, the present invention is not limited to such an example.
As shown in the figure, if necessary, it is also possible to make several stages on the upstream side each into a single stage and expose the outer surface of the shaft 1 between them. That is, in FIG. 7, the most upstream wheel 3a and the wheel 3'a disposed adjacent thereto
are each made into a single stage, and wheel 3a and wheel 3'a
The gaps between the wheels 31a and 3 are sufficiently widened. and wheels 3a and 3
'a are each laterally connected to a trick ring 13. In a turbine rotor configured in this way,
Further, from the turbine rotor of the embodiment shown in FIG.
The temperature difference between the wheel and the shaft can be reduced.

In addition, in FIG. 7, C is the wheel 3 located at the most downstream position.
Only wheel C is locked to wheel bore key 4 by wheel bore key 4.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing a conventional turbine rotor, Fig. 2 is a cross-sectional view showing stress corrosion cracking occurring in the wheel bore key groove, and Fig. 3 is a longitudinal cross-sectional view showing a turbine rotor according to an embodiment of the present invention. 4 is an enlarged perspective view of the wheel shown in FIG. 3, FIG. 5 is an enlarged vertical sectional view of the wheel and torque ring shown in FIG. The perspective view and FIG. 7 are longitudinal sectional views showing another embodiment of the turbine rotor of the present invention. 1.......Shaft 2...Blade 3.3a, 31) 13cm・*I/L/4.6・
...Wheel bore key 5 ...... Locking key 8 ...
・・・・・・Wheel radial key 9・・・・・・
・・・・・・Hub part 10・・・・・・・・・Wheel radial key groove 11・・・・・・・・・Annular groove 12・・・・・・・・・...Protrusion 13...Torque ring 15...
......Torque ring bore keyway 16...
・・・・・・・・・Keyway 17・・・・・・・・・ Torque Ring Bore Key Representative Patent Attorney Sa Suyama −

Claims (1)

[Claims] (1) In a turbine rotor in which a plurality of wheels having blades are fitted along the axial direction of a shaft, at least the most upstream wheel among the wheels is a wheel disposed adjacent to the downstream side. and a C-arranged wheel adjacent to the downstream side of the wheel disposed at a distance, and connected by a connecting means to a torque ring that transmits torque to the shaft. A turbine characterized in that a plurality of installed wheels are connected to each other by connecting members through minute gaps, and at least one of these wheels located at the most downstream position is locked to the shaft by a key. Rotor.