JPS59108805A - Turbine moving blade fixing device - Google Patents

Abstract

PURPOSE:To eliminate one-sided contact between a moving blade hook and the hook at a disc implanting part by bending the engaging surface between the hook of a moving blade, which is provided with an axial-entry-type blade implanting part, and a groove of a rotor disc in the axially circular-arc shape. CONSTITUTION:A hook 3 of a moving blade 1 at its implanting part and a hook at a disc 4 implanting part are formed in such a manner that they are axially curved to form circular arcs toward the center of the disc 4. Besides, the direction of the arc is set perpendicular to that of the principal stress of the hook due to the centrifugal force. With this contrivance, the hook surface of the moving blade 1 and that of the disc 4 are brought into smooth contact on the entire surface, thereby eliminating one-sided contact between the two.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to turbine blades, particularly axial blades [Technical Background of the Invention and Problems thereof] Conventional axial entry type turbine rotor blade fixing devices include: As shown in Fig. 1, a rotor blade 1 and a blade effective part 2
A blade embedding hook 8 integrally formed with the rotor disk 4 and a corresponding embedding portion ls5 of the rotor disk 4 are formed horizontally with respect to the axial direction, and the blade is installed horizontally into the rotor disk 4. It has been known. This fixation device is
It has a structure in which the centrifugal force of the wing is supported by the storm hook 8 and the hook 6 of the disk, and if the wing centrifugal force acting on the hook part is evenly distributed, the shearing area will be strong in terms of strength,
In addition, since the contact surface between the blade and the implanted portion of the disk is large, it has a vibration damping effect and is a blade fixing device with excellent vibration strength.

However, in the case of a long blade with a large centrifugal force such as a low-pressure final stage tool, the centrifugal force applied to the blade implant part is not uniform, and the strength of the conventional structure may be impaired for the following reasons. In other words, a long blade such as the final stage tool has a wide root section due to the large centrifugal force, and its R root section has a wide shape in terms of fluid performance, as shown in Figure 2. The part is thick and the leading edge 7. It has a shape that becomes thinner toward the rear edge 8. The centrifugal force acting on such a blade is proportional to the area distribution, and the 8th
As shown in the figure, the distribution of the centrifugal force F in the underground base part 9 and the implantation hook s8 is large in the center in the axial direction and small at both ends, and the principal stress σ at the implantation hook part is the centrifugal force distribution The distribution is similar to 9, and the direction tends to be toward the center of gravity of the entire wing, that is, bending occurs at both axial ends of the implant hook. Therefore, in the conventional wing implantation structure, the base part 9 and the implantation hook part 8 are horizontal in the axial direction and have a uniform thickness, and in other words, the rigidity is uniform, so the implantation including the base part and the wing hook part is The entire group extends in the center in the axial direction and is curved in an arc outward from the center of the disk. On the other hand, in the disc implantation part, the deformation due to the centrifugal force is almost uniform in the axial direction, and as a result, the connection part between the wing implantation part hook 8 and the corresponding disc implantation part hook 6 is partially warped. will occur.

Such a one-piece abutment does not locally absorb the centrifugal force of the blade, and excessive centrifugal stress is generated.In addition to shear, vibrations caused by uneven flow, etc., use the one-piece abutment as a fulcrum. This makes it easier to fit in, increasing the vibration stress in this area and significantly lowering the fatigue strength.In the worst case scenario, the wing implant may suffer fatigue damage and the wing may fly off.

[Purpose of the invention]

The present invention has been made to eliminate the drawbacks of the conventional device described above, and it prevents the hooks of the blade implantation portion and the disk implantation portion from touching one another, and eliminates the generation of excessive centrifugal stress.
It is an object of the present invention to provide a fixing device for a turbine rotor blade that can prevent a decrease in fatigue strength due to an increase in vibration stress.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized in that the fitting surface between the hook of the R implantation part and the 7g of the rotor disk that fits into this hook is curved in an arc shape in the axial direction. It is.

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in FIGS. 4 and 5. Note that the same reference numerals as in FIGS. 1 to 8 are given to the same reference numerals, and the explanation thereof will be omitted.

FIG. 4 is a diagram illustrating a rotor blade equipped with a rotor blade fixing device according to the present invention. As shown in FIG. 4, a wing base group 9 is provided below the active part 2 of the movable part g1, and the bottom surface 10 is curved in an arc toward the center of the disk in the axial direction. The hook 8 of the wing-embedded portion into which the blade is inserted is curved into an arc Φ toward the center of the disk in the axial direction, similar to the bottom of the multi-row clasp. To explain this curved structure in detail, as shown in FIG. 6, the wing base bottom 10 and the implant hook 8 are each formed by -circular arcs γ1 to γ, the radius of which increases as the disk center t1 approaches. The center of each arc coincides with a point on the outer circumferential side of the disk, that is, on the tip side of the blade. On the other hand, the hook 6 of the disk implantation part into which the blade implantation part fits is, like the blade, an arcuate shape having a large radius around a point on the outer circumferential side of the disk. Note that the centers of the arcs of the blade and the disk-embedded portion coincide with each other. In this way, by making the implantation parts of the blades and discs arc-shaped with one point as the center, the blades can be easily inserted into the discs by drawing an arc with the center of each arc as a reference, and the blades can It is possible to maintain uniform clearance for the hooks of the disc implants throughout.As with the seven wings, the bottom of the wing base is arcuate in the axial direction, making it thicker in the center and providing greater rigidity. Become.

Increasing the rigidity of the center of the wing base in this way has the effect of preventing the expansion of the center of the wing platform, whereas the centrifugal force distribution of the wing acts more strongly in the center as described above. It has the effect of smoothly transmitting the centrifugal force of the blade effective part to the blade embedded hook part and making the centrifugal stress distribution of the hook part almost uniform in the axial direction. In addition, the axial bending of the wing hook surface can be reduced by determining the arc shape to be perpendicular to the principal stress due to centrifugal force, as shown in Figure 5. The grooves of the disc implantation part are connected smoothly on the entire surface, and the centrifugal force of the wing is transmitted smoothly to the disc side through the hook surface of the implantation, and the increase in local stress is prevented by eliminating uneven contact. be done.

It goes without saying that the arc shape increases the shearing surface of the implantation hook and improves the implantation strength compared to the conventional structure:
b Regarding the vibration in the axial direction, which is the main cause of fatigue damage in vibrations of 6° stationery, since the low joint part with the disk is arcuate like wood, the form of vibration is that the force is applied in the tangential direction of the implanted material. However, since the force due to centrifugal force acts on the same arc in the direction perpendicular to the hook surface, it is damped by friction and the vibration stress is reduced. Of course, it is clear that the vibration damping effect is improved because the 4NN suspension has an arcuate shape and the contact surface increases compared to the conventional one.1 [Effects of the Invention] According to the present invention, the bottom of the wing base and the By making the implantation hook part and the corresponding disc implantation part curved in the axial direction, the stress caused by the centrifugal force of the wing is made uniform and low at the hook part where it passes through the implantation fitting part. It can provide a mobilization fixation device with improved vibration damping effect and excellent fatigue strength.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a conventional axial entry one-way turbine mobilization fixing device, and Fig. 2 is the same as Fig. 1! 8II
Figure 8 (,) is the conventional one at the root of the effective part of the wing. 1L
ll@Curve diagram showing the centrifugal force distribution at the base, Figure 8 (b)
8 is a side view showing the implantation hook portion, FIG. 8<c) is a principal stress distribution diagram of the implantation hook portion, FIGS. FIG. 5(,) is a side view of FIG. 4, and FIG. 5(b) is a stress distribution diagram of the implantation hook portion. 1... Moving blade, 8... Wing extension hook, 4
... Rotatisf, 5... Implanted part 1, 6...
hook. (7117) Substitute worker Patent attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2 Figure 4 (α) Figure 5 (α) (b) 22

Claims (1)

[Claims] A fixing device for a turbine rotor blade comprising a rotor blade having an axial entry type blade implantation portion formed by a plurality of hooks in the leg portion, and a rotor disk having a groove that fits into the implantation portion; A fixing device for a turbine rotor blade, characterized in that a fitting surface between a hook and a groove is curved in an arc shape in the axial direction.