JPS59190401A - Turbine rotor - Google Patents

Abstract

PURPOSE:To ease detection of a stress corrosion crack of a key groove by providing a detection hole in an angle part between a wheel radial key groove, formed on the side of a turbine wheel, and a key fitted to said groove. CONSTITUTION:A wheel radial key groove 10 is formed on the side of a hub part 9 of a wheel fitted to the shaft of a turbine rotor, and a key 13 is fitted and connected to said key groove. A hole 14 for detecting a stress corrosion crack of the key groove 10 is provided in an angle part between the wheel radial key groove 10 and the key 13. Thus, the stress corrosion crack 10 can be easily detected without disassembling the turbine rotor.

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 (2), long blades with a large average diameter are used to flow a large amount of steam.

In order to solve manufacturing technology and economic problems in such a huge turbine rotor C2, 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 attached to the rotor. A so-called ablation wheel that fits onto the shaft is adopted. Figure 1 shows a steam turbine rotor with such an ablation wheel, and in Fig. 1, reference numeral 1 indicates the shaft of the turbine rotor. There is. A plurality of ablation wheels 3 having blades 2 on the outer periphery are fitted onto the shaft 1 by wheel bore keys 4 along the axial direction f1 of the shaft 1.

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

In a turbine rotor configured in this manner, the steam energy is converted into torque by the blades 2 (2) and then transmitted to the wheel 3C2, and the torque transmission from the wheel 3 to the shaft 1 is the same as that of the wheel 3. This is done by the friction force due to the surface pressure f2 of the shrink fit surface and the wheel bore key 412.

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, creating a temperature difference with the shaft 1, and the wheel 3 is heated up faster than the shaft 1. If the wheel 3 becomes loose, the torque will be transmitted from the wheel bore key 4]2.The inner surface of the wheel 3 is shrink-fitted to the shirt l-1.
While keeping the surface pressure between C and C at a constant level, the stress in the tangential direction of the inner surface of C is maintained at a uniform level of 1.

[Problems in the Background Art] However, in the above-mentioned S-shaped turbine rotor, the inner surface C2 of the wheel 3 is provided with a wheel bore key groove 6 for fitting the wheel bore key 4, and this wheel Around the bore key groove 6; two stresses are concentrated and the second
As shown in Figure 2, stress corrosion cracking 7 (scc) may occur around the wheel bore keyway 6. In particular, the wheel 3 that is exposed to an atmosphere of about 130 to 150°C has a high stress corrosion cracking susceptibility due to the temperature dependence of its material. There is a possibility that stress corrosion cracking 7 will occur.

[Object of the Invention] The present invention has been made in response to these two conventional circumstances, and can eliminate the risk of stress corrosion cracking occurring in key grooves formed due to wheel counterfeiting, and can also prevent stress corrosion cracking. It is an object of the present invention to provide a turbine rotor that can easily perform detection and reliably transmit torque between a wheel and a shaft.

[Summary of the invention] The present invention provides a wheel having blades in the axial direction C1 of the shaft.
A plurality of wheel radial key grooves are formed along the sides of the wheels, and two wheel radial key grooves are fitted along the two wheel radial keys so that the wheels are engaged with each other. In the turbine rotor, an inspection hole for inspecting the wheel radial keyway is formed between a wheel radial key fitted in the wheel radial keyway and a corner of the wheel radial keyway. .

[Embodiment of the Invention] The details of the present invention will be explained below using an embodiment (two embodiments) shown in Drawing C.

FIG. 3 shows a turbine rotor according to an embodiment of the present invention, and in FIG. A plurality of wheels 3 having blades 2 implanted on the outer peripheral surface g' are fitted onto the shaft 1 along the axial direction. Then, the most upstream side l of the shaft 1
The two wheels 3a are arranged side by side with the downstream wheel 3b with a certain gap, and the outer surface of the shaft 1 is exposed. Further, the wheels on the downstream side of the wheel 3b are continuously arranged side by side with a small gap between them.

Wheel 3 located upstream 1111 of the turbine rotor
b is a connecting member f consisting of, for example, a wheel radial key 8, which transmits torque to the adjacent wheel 3C;
The two are connected to each other. The wheel 3a located independently at the most upstream Ill is connected to a torque ring 15 in order to transmit torque to the shaft I, and the torque ring 13 is formed with a wheel bore keyway 6 as in the conventional case. Wheel bore key 4 is in bore key groove 6
is inserted and fitted onto the shaft 1.

Furthermore, the wheel 30 disposed downstream of the steam inlet of the turbine rotor has the wheel bore keyway 6 as described above.
is formed, and a wheel bore key 4 is inserted into this wheel bore key groove 6. The downstream side of the wheel 3C (wheel 3d, which is used in tandem, has a low steam temperature as in the past, so there is a temperature difference between the shaft 1 and the wheel 3d. Even if the shrink-fitting blood pressure drops, the torque is transmitted to the wheel 3C by the radial key 16 built between the wheel 3d and the wheel 30, and then to the wheel bore key 4. is transmitted to shaft 1.

On the other hand, in this embodiment, one wheel radial key 8 is installed between each of the wheels 3 arranged in parallel, but the number of radial keys 8 and 'h is determined by the transmission torque, and a plurality of them may be installed. . However, when one wheel radial key 8 is provided, in order to minimize the unbalance of the entire turbine rotor as a rotating body, they are arranged alternately (: arranged) with an angular difference of 180 degrees from the upstream side to the downstream wheel. .

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

Two wheel radial key grooves 1O are formed on both sides of the wheel radial key groove 9 with a corner difference of 180 degrees, and the lower end and upper end (two wheel radial key grooves 10) for this wheel radial key groove are Contact annular stress relief: Japanese groove 11
is formed. A rectangular wheel radial key 8 is inserted into the wheel radial key groove 10 of the wheel 3, and a holding portion 12 consisting of a convex portion formed at one end of the wheel radial key 8 is inserted into the stress relief groove 11 (the second inserted portion). This prevents the wheel radial key 8 from coming off due to the centrifugal force caused by the rotation f2 of the turbine rotor.

Fig. 5 shows details of the wheel radial keyway 10 formed in the hub part 9 (2) of the wheel 3; The wheel radial keyway 10, as shown in the figure,
The corner portion is formed by a circular arc having a radius R', and the bottom surface portion of the wheel radial keyway lO connecting the corner portions is connected by a curved line having a radius R.

That is, by forming the wheel radial key in this manner, stress concentration occurring in the wheel radial key groove 10 can be efficiently alleviated.

Figures 6 and 7 show details of the wheel radial key 8.
As shown in FIG. 7, the lower end of the holding part 12 is composed of a stress relief groove 11 and a wheel radial key 8 inserted into it due to the centrifugal force caused by the rotation of the turbine rotor. Key part 1 of the 0 wheel radial key 8 that prevents the key from jumping out toward the outer circumference
3 is f2, wheel radial keyway 1 as shown in Figure 5.
It has a shape that protrudes toward the bottom surface of the wheel radial key groove 10, and the contact portion between the bottom surface of the wheel radial key groove 10 and the key part 13,
It is formed in a shape with four arcuate curved protrusions.

That is, when this wheel radial key 8it and wheel radial key e10 are inserted, an inspection hole '14 is formed between the wheel radial kill groove 10 and this wheel radial key 8 (two configurations are used). The stress generated in the wheel radial keyway 10 can be easily reduced by using the hole 14 without disassembling the turbine rotor.
Partial corrosion cracks can be placed horizontally.

Figure 5 and Figure 8 and Figure 9 for Mr. Tsutomu show the details of the two-wheel radial key 17 (-, without compromising the original purpose of torque transmission, the inspection was carried out in the space of hole L4. In order to ensure a sufficient degree of is a modified example formed by an arc-shaped curved surface.

Figure i10 is an enlarged view of the torque ring 15 in Figure 3, and in the figure, reference numeral 15 indicates the torque ring. A radial key 18 is formed on the side surface of the torque ring 15 in the radial direction at an angle of 180°, which is integrally machined from the torque ring 15.
A wheel radial keyway IO is provided in the wheel 3a arranged in parallel with the radial key 18 at a position where the radial key 18 and the radial key 18 are fitted together. Further, a wheel bore key groove 6 is provided on the inner periphery of the torque ring 15 with an angle difference of 90 degrees from the radial key 18.

FIG. 11 shows details of the radial key 18 formed on the side surface f2 of the torque ring 15. In FIG. C2, the radial key 18 has a trapezoidal protrusion shape.

That is, this radial key j8 is inserted into the wheel radial keyway 10 (2 in the case of two insertions, the wheel radial keyway I
The inspection hole 14 is formed between the radial key I8 and the radial key I8, and the purpose of the inspection hole 140 is as described above.

In the turbine rotor configured as described above, torque from the wheel 3 is transmitted to the surface pressure (sheath 7) 1 of the shrink fit surface of the wheel 3 (due to two frictional forces) during normal operation of the turbine rotor.

On the other hand, if the wheel 3 with a smaller heat capacity is heated faster than the shaft 1 and the wheel 3 on the steam inflow side becomes loose, then the torque applied to the loosened wheel 3 is transmitted to the shirt 1 via the adjacent wheel 3. Ru. For example, when all of these upstream wheels 3 become loose and cannot transmit torque to the shaft I, the wheels 3 are disposed at the most downstream position.

Torque is transmitted to the shaft 1 through the wheel bore key 4 (wheel 3 that is locked and pulled to the shaft 1 by two twists).

In addition, when provided alone like the wheel 3a,
An exposed portion of the shaft 1 is provided between the adjacent wheels to reduce the temperature difference between the shaft 1 and the wheel 3a.
I try to reduce it. However, assuming that the wheel 3a should come loose, a torque ring 15 is arranged in parallel so that torque can be transmitted to the shaft 1.

The turbine rotor configured in this way has a capacity of 1l-t.
, the inner circumferential surface of the wheel radial keyway 10 (two stress relaxation grooves 1) is formed in the hub part 9 of the wheel 3, so the stress generated on the ablation surface f2 of the wheel 3 with the shaft 1 is After being relieved by the stress relief groove 11, the stress is transmitted to the wheel radial keyway 10, so the stress applied to the wheel radial keyway 10+ is assumed to be very small.
Stress corrosion cracking of the wheel radial keyway 10 can be prevented.

In addition, in this embodiment, the depth of the wheel radial keyway 10 and the stress relief groove 11 are the same (the depth of the stress relief groove 1 is explained as two). Of course, the depth may be deeper than 10, or it may be shallower.

In the turbine rotor configured in this way,
Since the wheel bore keyway 6 formed on the inner peripheral surface C2 of the wheel 3 disposed on the steam inflow side can be removed, the stress corrosion cracking 7 that conventionally occurred in this part can be eliminated. .

-! In addition, the wheel 3 located at the most downstream position among the wheels 3
The wheel bore key 4 locks the shaft L [2], but the wheel 3 in this part has the same structure as the conventional one since there is relatively little risk of stress corrosion cracking even if the C1 stress concentration mentioned above occurs. is sufficient.

[Effects of the Invention] As described above, according to the turbine rotor of the present invention, the wheel radial key groove formed on the side surface of the wheel and the wheel radial, which is a connecting member between the wheel, is The turbine rotor It is possible to easily inspect the stress corrosion cracking that occurs in the wheel radial keyway without disassembling the wheel, which can contribute to improving the reliability of the turbine rotor.

[Brief explanation of the drawing]

Figure 1 is a longitudinal to j-plane view showing a conventional turbine rotor;
Figure 3 is a vertical cross-sectional view showing stress corrosion cracking occurring in a part of the wheel, Figure 3 is a vertical cross-sectional view showing a turbine rotor according to an embodiment of the present invention, and Figure 4 is an enlarged view of the wheel in Figure 3. Perspective view,
Figures 5 and 8 are top views showing the shape of the wheel radial keyway, Figures 6 and 9 are enlarged views of the wheel radial key in Figure 4, and Figure 7 is the figure 6. 9 is a longitudinal sectional view, FIG. 10 is an enlarged perspective view of the torque ring shown in FIG. 3, and FIGS. 11 and 12 are top views showing the shape of the wheel radial keyway. 1...Shaft 2...Blade 3...Wheel 8...Wheel radial key 9...Hub part
10...Wheel radial key groove 11...Stress relief daily groove 14...Inspection hole 15...Torque ring 17...Wheel radial key 18...Radial key agent Patent attorney Noriyuki Chika (1 other person) Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 Figure 9 Figure 10 Figure 8 Figure 11 Figure 12

Claims (1)

[Claims] A plurality of wheels having blades are fitted along the axial direction f1 of the shaft, and a wheel radial key groove is formed in the side surface C of the wheel, and a wheel radial key is fitted into the wheel radial key to connect the wheels to each other. In the turbine rotors that are arranged so as to be engaged with each other, between the wheel radial key fitted in the wheel radial key 7+4 and the corner of the wheel radial key groove (1) an inspection for inspecting the wheel radial key groove; Turbine rotor 0 characterized by forming holes