JPS6148607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine rotor blade connection device for connecting mutually adjacent turbine rotor blades in a turbine wheel such as a steam turbine or a gas turbine.

In a turbine rotor blade coupling device that damps vibrations of the turbine rotor blade of a turbine wheel, which is a long blade that is twisted mainly from the blade root to the tip, for example, a connecting member as shown in Fig. 1 is attached to the rotor blade tip. It is installed. In such a conventional connecting member, there is a phenomenon in which the rotor blades twist back due to centrifugal force during rotation of the rotor blades 1 and 2, and the steam inlet end 1b and steam outlet end 1 of the rotor blades are
A and A, there is a difference in the amount of radial elongation due to centrifugal force, and unreasonable prying force acts on the horizontal protrusions 4 and 5 of the connecting member 3.
There is a possibility that the protrusions 4 and 5 will break during turbine operation.

In order to eliminate the above-mentioned prying force, the horizontal protrusion from the connecting member is removed and another engagement means is provided, and the side wall of the connecting member is brought into contact with the rotor blade surface to prevent the twisting back phenomenon of the rotor blade. It is conceivable to adopt a so-called contact type connecting member for restraint, and as one of the structures, the present applicant has proposed Japanese Patent Application No. 55-74367
−2404). According to experiments conducted by the applicant, when the contact-type connecting member of the above application is adopted, fretting corrosion (hereinafter FC
) may occur. F on the contact surface.
If C. occurs, microcracks in the FC will develop due to surface pressure, and there is a risk that the connecting member will eventually break. Since the connecting member is attached to the outer peripheral side of the rotor blade and has a high circumferential speed, there is a concern that if it breaks, it will lead to a serious accident, and its reliability is strongly required.

It is an object of the present invention to damp the vibration of the rotor blade by restraining the torsional return acting on the turbine rotor blade, and to prevent fretting even if relative minute slip occurs in the contact portion of the connecting member. An object of the present invention is to provide a strong and safe turbine rotor blade coupling device that prevents occurrence of corrosion.

The gist of the present invention is to provide a turbine rotor blade coupling device in which plate members protruding in opposite directions are provided on the leading edge side and the trailing edge side of the tips of the turbine rotor blades, and a coupling member is engaged with the plate members of adjacent rotor blades. , a plurality of these connecting members are provided, one of the connecting members is engaged with a plate member on the leading edge side of the rotor blade, the other connecting member is engaged with a plate member on the trailing edge side of the adjacent rotor blade, and these connecting members are engaged with the plate member on the trailing edge side of the adjacent rotor blade. Both connecting members are disposed in such a manner that a portion thereof overlaps with a plate member of an adjacent rotor blade, and the two connecting members are brought into contact with each other during turbine operation to engage adjacent rotor blades. This restrains the rotor blades from twisting back and dampens the vibrations of the rotor blades. At the same time, the contact area of the connecting member with other connecting members or the rotor blades is coated with thermal spraying, overlaying, or residual compression to increase hardness. A turbine rotor blade coupling device that prevents the occurrence of fretting corrosion caused by relative microslip by either shot peening to generate stress or surface hardening treatment to increase hardness and generate residual compressive stress. .

Next, one embodiment of the present invention will be described with reference to the drawings. In FIG. 2, the drawing shows the situation seen from the outer peripheral side of the turbine rotor blade. Turbine rotor blade 1
are provided with protruding eaves 6a and 6b. Further, the adjacent turbine rotor blade 2 is also provided with eaves 7a and 7b at the tip of the rotor blade, respectively, similarly to the rotor blade 1. The eaves 6a of the turbine rotor blades 1 and the eaves 7b of the turbine rotor blades 2, which are located close to each other, are assembled and adjusted so that a small gap is maintained between them. Further, rotor blade connecting members 8 and 9 are installed between the blade tips of the turbine rotor blades 1 and 2.
This rotor blade connecting member is connected to the eaves 6a on the trailing edge side of the rotor blade 1.
A connecting member 8 attached to the lower surface of the rotor blade 2 and a connecting member 9 attached to the lower surface of the eaves 7b on the leading edge side of the adjacent rotor blade 2 are formed as a set, and the upper surface of each connecting member 8, 9 Cylindrical pins 10 and 11 are integrally formed in the. The pin 10 and the pin 11 are respectively connected to the eaves 6a of the rotor blade 1.
The through hole 12 provided in and the eaves 7b of the rotor blade 2
It is adapted to be fitted and locked into a through hole 13 provided in the. These connecting pieces 8 and 9 are formed in a rhombus shape, and have slightly protruding contact surfaces 14 and 15 on the end faces facing the blade surface of the rotor blade, and contact surfaces 16 and 17 near the pin 11, respectively. Moving blades 1, 2
While in contact with the blade surface of the connecting member, both connecting members are in contact at the contact surface 18 and restrained from twisting back. In addition, the contact surfaces 14, 15, 16 of the connecting member during the rotor blade rotation,
Relative microslip occurred at 17, 18, 19, and 20.
21, as there is a possibility that FC may occur.
As shown in Nos. 22, 23, 24, 25, 26, 27, and 28, hard alloys are thermally sprayed or overlaid, shot peened, and surface hardened to prevent FC. Next, the structure of the connecting member will be explained. FIG. 3 shows the eaves 7 of the rotor blades 2 of the connecting member 9.
Figure b shows the shape before assembly. A cylindrical pin 11 is formed in the center of the upper surface of the connecting member 9, and is inserted into a through hole 13 provided in the eaves 7b on the leading edge side of the rotor blade 2 with a slight gap between the pins 11 and 2.
The pin 11 is fixed to the eaves 7b with the top of the pin 11 somewhat loose. Contact surfaces 15 and 17 are formed at the end of the side surface of the connecting member 9 facing the blade surface of the rotor blade 2 and at the bottom of the pin 11 to contact the blade surface of the rotor blade. A contact surface 29 is formed on the side for contacting an adjacent connecting member. Further, during rotor blade rotation, the contact surface 29 of the connecting member contacts the adjacent connecting member, the contact surface 20 contacts the inner surface of the through hole 13, the contact surface 15,
Reference numeral 17 indicates the possibility of relative minute slippage occurring between the blade surface of the rotor blade and FC, so as shown in FIG.
It has surface-treated surfaces 22, 24, 26, and 28 which have been subjected to thermal spraying or overlaying, shot peening, or surface hardening treatment with a hard alloy for prevention. It goes without saying that the connecting member 8 also has the same shape as the connecting member 9.

First, the vibration suppression function will be explained. The connecting members 8 and 9 mainly use the pins 10 and 9 as a twist return restraining force.
11 and contact surfaces 14, 16, 15, 17, 18 to engage with adjacent rotor blades 1, 2. When the rotor blades 1 and 2 vibrate in the X direction shown in FIG. 1
8 friction exhibits a large vibration damping effect. On the other hand, when the rotor blades 1 and 2 vibrate in the Y direction, that is, the axial direction, the connecting members 8 and 9 mainly contact the lower surfaces of the eaves 6a and 7b, which are the centrifugal force receiving pressure surfaces of the connecting members 8 and 9. The friction on the top surface is large and has a vibration damping effect. Next, when vibrating in the Z direction, that is, the torsional direction of the rotor blades, friction between the contact surfaces 18 of the connecting members 8 and 9 and centrifugal force occur between the pressure receiving surfaces of the upper surfaces of the connecting members 8 and 9 and the lower surfaces of the eaves 6a and 7b. A great vibration damping effect can be expected due to the friction and further the mutual contact between the adjacent eaves 6a and 7b.

Next, the FC prevention effect of the surface treated surface will be explained. Surface treatment methods include thermal spraying of hard alloys such as WC and CrC, overlaying of hard alloys such as Stellite,
Surface hardening treatments such as induction hardening, flame hardening, nitriding, and shot peening are performed singly or in combination. These FC prevention methods can be broadly classified into those that increase surface hardness and those that generate residual compressive stress on the surface. Increasing the surface hardness improves wear resistance, prevents FC itself, and has the effect of preventing the formation of microcracks. Materials that generate residual compressive stress on the surface are less effective than materials that increase hardness in preventing microcracks caused by FC, but they prevent the propagation of microcracks when they occur, and improve the strength of the connecting member. This has a great effect in preventing breakage. Among the measures taken in the present invention, thermal spraying and overlaying of hard alloys have the effect of increasing the hardness of the surface, shot peening has the effect of residual compressive stress, and surface hardening treatment has the effect of increasing the hardness of the surface. Have more than one. FIG. 5 shows the results of experiments to determine the effects of these treatments on FC. In Fig. 5, the limit stress for fretting corrosion occurrence, indicated by the solid line A, is the bending stress in the minimum connecting member where the contact surface where relative microslip occurs is rough and FC (mainly microcracks) occurs. In other words, the acting stress shown by the dashed line B is the bending stress that occurs in the connecting member while the rotor blade is rotating. Therefore, if the stress B acting on the connecting member is larger than the FC generation limit stress, FC will occur in region C, and if it is smaller, FC will not occur in region D. Thermal spraying of hard alloys has a highly hard and wear-resistant surface, so it has a much higher limit stress for FC generation than other types, so the margin stress E for not generating FC is large, making it the most effective method for preventing FC. There is. Next, hard alloy overlay, which has a hardness second only to thermal spraying, is effective. Surface hardening treatment does not have the same hardness as thermal spraying or overlaying, so it is a little less effective in preventing FC, but it is an effective method because it combines the effect of preventing FC with the effect of preventing crack propagation due to residual compressive stress. Shot peening does not significantly improve hardness, so it has a low FC prevention effect, but it has a high residual compressive stress, so it has a significant crack growth prevention effect. Furthermore, surface hardening treatment and shot peening have the advantage that they are simple processing methods and do not require large-scale and expensive processing equipment. When the above process is performed, when the hardness of the connecting member material is low and the applied stress is high,
If you select the treatment that best suits the strength requirements determined by the situation where the connecting members are placed, such as thermal spraying of hard alloys (WC, CrC, etc. are selected depending on the conditions), you can obtain an economical prevention effect. It will be done.

As described above, according to this embodiment, by applying surface treatment to the contact surfaces of the connecting members, it is possible to prevent FC, further improving reliability, and the effect is extremely large.

According to the present invention, the vibration of the rotor blade can be damped by restraining the torsional return acting on the turbine rotor blade, and the occurrence of fretting corrosion on the contact surface of the connecting member can be prevented by surface treatment, which also causes problems in terms of strength. It is possible to realize a safe connection device for turbine rotor blades without any problems, and the reliability of the turbine is further improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing a conventional turbine rotor blade coupling device, Fig. 2 is an assembly state diagram of a turbine rotor blade coupling device which is an embodiment of the present invention, and Fig. 3 is a structure of a coupling member of the present invention. FIG. 4 is a perspective view showing a surface treated surface for preventing fretting corrosion of the connecting member, and FIG. 5 is an explanatory view showing the fretting corrosion preventing effect of each surface treatment. 1, 2... Turbine moving blade, 1a... Moving blade leading edge side, 2b... Moving blade trailing edge side, 6a, 6b... Moving blade eave, 8, 9... Connection member, 10, 11... Pin, 12 , 13... Through hole, 14, 15, 16,
17, 18……Contact surface, 19, 20, 21, 2
2, 23, 24...FC prevention surface treatment surface, 25
...Contact surface.

Claims (1)

[Claims] 1. A plate member is provided at the tip of the turbine rotor blade, protruding in opposite directions on the leading edge side and the trailing edge side of the rotor blade,
A plate member on the leading edge side and a plate member on the trailing edge side of the adjacent rotor blades are arranged opposite to each other with a gap therebetween, and one of the pair of connecting members is engaged with the plate member on the leading edge side of the rotor blade,
The other connecting member is engaged with a plate member on the trailing edge side of an adjacent rotor blade, and the two connecting members are brought into contact with each other due to twisting back that occurs in the rotor blade during turbine operation, thereby connecting the adjacent rotor blades. A turbine rotor blade coupling device, characterized in that at least one of the contact surfaces between the coupling members and the contact surfaces between the coupling members and the rotor blades that are engaged with each other is subjected to surface treatment. 2. The turbine rotor blade coupling device according to claim 1, wherein the surface treatment includes thermal spraying a hard alloy such as WC type, CrC type, etc. on the contact surface. 3. The turbine rotor blade coupling device according to claim 1, wherein the surface treatment includes overlaying a hard metal such as stellite on the contact surface. 4. The turbine rotor blade coupling device according to claim 1, wherein the surface treatment includes surface hardening treatment such as induction hardening or flame hardening on the contact surface. 5. The turbine rotor blade coupling device according to claim 1, wherein the surface treatment includes shot peening the contact surface.