JPS59108802A - Moving blade cover installing device - Google Patents

Abstract

PURPOSE:To heighten both rigidity and vibration damping effect of a group of moving blades by forming a plurality of indents at the crest part of a tenon of a moving blade cover, which is inserted into a hole formed on the moving blade, so that untwisting deformation of each blade under rotation becomes uniform. CONSTITUTION:The tenon of a moving blade cover is inserted into a lateral hole 3b formed at the trailing edge side of the moving blade. A plurality of indents 11 are formed on the crest part of the tenon in such a manner that the indent 11 is shallower as it is closer to the trailing edge 10 of the blade. The tip of the tenon is expanded as shown by the broken lines in the figure in order to fix the moving blade cover. By providing a plurality of indents like this, the sectional rigidity of the caulked part becomes almost equal in both longitudinal and lateral directions, thereby keeping the untwisting deformation not-too-tight and uniform during rotation.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a coupling device for turbine rotor blades, and particularly relates to a device for attaching a rotor blade cover with an improved structure for attaching a cover attached to the tip of a turbine rotor blade. .

[Technical background of the invention and its problems]

In general, the rotor blades used in the low-pressure final stage of turbines have long blades and large torsions in the blade length direction, and during rotation they undergo not only tensile deformation due to centrifugal force, but also return deformation due to torsion. occurs. Furthermore, due to the long blade span, the natural frequency decreases, and the number of natural frequency modes that should avoid resonance at continuous rotation speed increases, inevitably causing vibration problems.

In order to solve such problems of deformation and vibration intensity, it is safe to use a turbine rotor blade coupling device that increases the rigidity of the blade group structure and has an excellent vibration damping effect.

Conventionally, as shown in FIGS. 1 and 2, this connection device has been made by using a horizontal hole 3 that passes through the wing tip 2 of an adjacent soldier 1.
Tenon 5 + 6 protrudes from the side of the cover body 4.
'c is inserted, and the top of one Tenon 5 is completely caulked and fixed to the wing, and the top of the other Tenon 6 is loosely caulked to the wing, thereby improving the rigidity of the blade group and the vibration damping effect. has been done.

However, in conventional coupling devices, especially for the loose caulking part of the cover installation part, the method of caulking the top end face of the tenon with a punch is generally adopted, but it is difficult to manage the clearance with this method, and the following For some reason, problems may arise in terms of strength. The variation in the amount of caulking caused by the punch is that the gap between each punch and the cover is not uniform, and the deformation (untwisting) of the untwisted screw during rotation becomes large in areas with large gaps, and hardly deforms in areas with small gaps. As a result, the difference in the deformation of the container causes the deformation of the blade to be localized, causing excessive stress at the base of the cover at that location, and in the worst case, causing damage such as cracking. As a result, there was a drawback that the strength was completely lost.

A moving blade cuckoo attachment device disclosed in Japanese Patent Publication No. 53-8010 is intended to solve these drawbacks. This rotor blade cover attachment device forms a bath-shaped recess 7 as shown in FIGS. 3(A) and (B) at the top of the tenon part on the loose caulking side, which is the part for attaching the rotor blade cover. Insert it into the horizontal hole 3 at the leading edge, and spread the top part 8 of the blade all the way around so that it has wings and gaps.
By loosely fixing it to the blade, it allows some degree of untwisting during rotation, and by keeping the gap constant, the untwisting deformation of the blade is uniform throughout the entire circumference, which relieves stress and has a vibration damping effect due to the loose fixation. It is intended to bring about.

In other words, the bathtub type α provided at the end of the tenon on the loose caulking side.
The structure in which the top of the groove is spread out over the entire station was developed in the 1970s.
This is the gist of the invention described in Publication No. 3-8010, and this structure can be applied to cover tenons whose cover tenon portions are cylindrical or whose material is soft without any problems in terms of strength.

However, in general, the tenon, which is the attachment part of the dynamic μ cover, is subject to bending force because it restrains the centrifugal force of the cutter body and the unreinforced blade to some extent, so the ib surface is increased in terms of strength and the bending rigidity of the tenon part is increased. Adopts a horizontally elongated oval shape L, and has hardness with excellent yield strength 12
Cr steel is used. When the above-mentioned invention is applied to such an elliptical tenon, the stiffness of the cross section in the longitudinal and lateral directions differs due to its shape, and it is difficult to uniformly spread the entire circumference. 9. Compression acts in the vertical direction when pushing and spreading in the horizontal direction, and compression acts in the horizontal direction when pushing and spreading in the vertical direction. If both are pushed and spread, excessive stress and strain will be applied to one of them. This results in unrestrained strain distribution and life, and cracks occur particularly in the tenon portion where the top portion is thin and has low rigidity. This lack of strength and cracking in the loose caulking part of the rotor blade cover is due to the fact that it is difficult to restrain the bending deformation caused by the untwisting of the rotating blade at the loose caulking part, and excessive stress occurs as in the past. This may cause damage to the cover tenon.

[Purpose of the invention]

An object of the present invention is to solve the problems caused by the above-mentioned prior art, and to fix the rotor blade cover loosely (loosely) to the blade without impairing the strength of the tenon part on the loosely caulked side. To provide a device for attaching a rotor blade that can uniformly and loosely maintain untwisted deformation of the entire circumference of the rotor blade, and appropriately plan for increasing the immediacy of the blade group and achieving a vibration damping effect. It is in.

[Invention planting]

According to the present invention, in order to achieve the above-mentioned object, a moving blade cover mounting device has a structure in which a plurality of indentations are formed at the top of a tenon integrally formed on both sides of a cover body. It is something.

[Embodiments of the invention]

What are the preferred embodiments of the present invention? : This will be explained with reference to FIGS. 4 to 6. The same parts in FIGS. 4 to 6 as those shown in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is an enlarged view of a rotor blade tip equipped with a rotor blade cover attachment device according to the present invention. A horizontal hole 3a is formed on the leading edge side of the tip portion 2 of the rotor blade, and a horizontal hole 3b is formed on the trailing edge side. A force S+4 is provided to cover the leading edge and trailing edge sides of the adjacent wing tips, and a tenon 5 is provided on the side of the cummer 4 to be completely caulked and fixed in the side hole 3a, and a tenon 5 is attached to the side hole 3b. A tenon 6 that is loosely crimped and fixed is formed integrally with the cover body. The tip of Tenon 5 is mechanically caulked in the same manner as in the past.

In this way, the completely caulked side was fixed on the leading edge side of the wing, whereas in the conventional example described above, both the true front line and the trailing edge were allowed. The deformation of the trailing edge 10 is larger than that of the leading edge 9, and the rigidity of the wing cross section is greater on the leading edge side, so if the tenon on the fully caulked side is placed on the trailing edge of the wing, the cover body will be placed on the trailing edge of the wing. As a result, excessive bending stress is generated in the tenon on the loose caulking side, which suppresses the deformation by a certain 8 degrees on the leading edge side where the blade has greater rigidity, and a gap is created on the leading edge side of the blade, and water droplets adhere to this gap.
This is because tenon causes erosion due to water droplets at the root, resulting in loss of strength.

On the other hand, if the leading edge of the blade is completely caulked as in the present invention, the above-mentioned problem does not occur and the cover attachment device according to the present invention can be used more effectively.

The present invention improves the structure of the tenon on the loosely caulked side, which is the attachment part of the rotor blade cup 9-, and its arrangement when inserted into the hole right next to it, which is shown in detail in FIG. That is, the tip of the loose caulking side tenon 6 has a plurality of caulking recesses 11, and at least two of these depressions 11 are formed at the tip.

The depth of the recess 11 is adjusted so that the recess on the trailing edge side of the blade becomes shallower, so that all deformation caused by untwisting the blade is uniformly applied to the recess caulking portion. As shown in FIG. 6, the inclination angle θ of the bottom of the recess is in the range of 0.5 degrees to 3 degrees, and this angle θ is determined by the length and twist angle and is arbitrarily selected.

The loose caulking side tenon according to the present invention has a horizontal hole 3 in the trailing edge of the wing.
The tip of the tenon is placed in contact with the side surface of the leading edge of b, and then the tip of the tenon is pushed out in an inclined manner as shown by the broken line. If the tenon on the loose caulking side is placed in the side hole in this way, the untwist of the wing will deform while moving closer to the leading edge, so the side of the hole on the leading edge side will move away from the tenon, and the side of the hole on the trailing edge will move closer. direction, therefore Tenon and Yokoana 3
It is possible to minimize the gap b and maintain the intended untwist angle. Of course, if the tenon on the loose caulking side is placed in the center of the hole and the gap between it and both sides of the hole is the same, it is necessary to widen the gap in order to maintain the intended untwist angle. The strength of the blade's gap will decrease, and if the gap is left as is, the untwist will be suppressed and the strength of the tenon will decrease.

The tip of the tenon on the loose crimping side has multiple depressions, and the tip of the tenon is crimped loosely against the day. Compared to the conventional method, the cross-sectional 1411 property of the crimped part is almost the same in the vertical and horizontal directions, and it is uniform in the circumferential direction. Due to strain deformation, stress is relaxed and strength increases. As shown by the broken line 12, the tip of the tenon after caulking does not have a straight line unlike the conventional one. This is because the centrifugal force, which is the stress that resides in the Tenon, is received by the inner surface of the hole, and the untwisting force is held by the side surface of the Tenon, so there is no need to spread the tip of the Tenon evenly around the entire circumference. This is because spreading the material around the entire circumference will actually reduce the strength.

〔Effect of the invention〕

As explained above, the wing cover mounting device according to the present invention has a plurality of notches at the tip of the tenon on the loose caulking side, and the depth of the notches is shallower on the trailing edge side, In addition, since the tenon is placed so as to be in contact with the inner surface of the leading edge side of the side hole of the wing, untwisting during rotation can be held evenly and loosely with the tenon on the loose caulking side, thereby relieving stress, and further reducing the strength caused by caulking. It has an appropriate vibration damping effect and strength.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the equipment with the conventional rotor blade cover installed, Figure 2 is a view showing the tenon caulking part of the equipment with the installation of Figure 1, Figure 3) and (B) are Japanese Patent Publication No. 53-8010. The rotor blade cover attachment disclosed in the publication is a detailed view of the device, FIG. 4 is a diagram showing an embodiment of the rotor blade cover attachment according to the present invention and shows the tenon caulking part, and FIG. This figure explains the untwist deformation and shows the shape of the blade at the tip of the wing.
FIGS. 6(A) and 6(B) show the rotor blade force and the like according to the present invention.
The installation is a detailed view of the device. 1...Wing, 2...Blade tip, k, 3b...Horizontal hole, 4...Rikiroku-15, 6...Tenon, 7.11...
・＜Homi. Applicant's agent Shizuo Hatano 7 Figure 2 Figure 3 (B)

Claims (1)

[Scope of Claims] 1. A cover main body, and a plurality of tenons formed integrally or integrally on both sides of the cover main body and inserted into holes formed in the rotor blade, the tenons of? ) The blade cover mounting device is characterized by having multiple grooves formed on the top of the tenon on at least one side of the blade. 2. The mounting device as claimed in claim 1, wherein the recess is formed on the loose caulking side tenon. 3. The attachment device according to claim 2, wherein the tenon on the loose caulking side is arranged so as to be in contact with the inner surface on the leading edge side of the hole formed in the trailing edge of the rotor blade.