JP2006063894A - Turbine moving blade group - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve structural reliability of a tenon and a shroud by reducing stress generated at a contact edge of the tenon and the shroud and suppressing condensation of corrosive product. <P>SOLUTION: At least a part of an inner circumference side end surface of the shroud and a blade shoulder are contacted around the tenon and part of vibration load transmitted by blade vibration is distributed to the blade edge to reduce vibration load transmitted to the tenon. An effect to reduce condensation of corrosive product is expected by suppressing flow of steam into a root part of the tenon. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a group of turbine blades having a combined structure of a tenon and a shroud.

  Conventionally, as for a technique related to a turbine blade group having a combined structure of a tenon and a shroud, as described in Patent Document 1, a method for shaping a blade tenon is used for the purpose of maintaining stable quality. There are provided ones and a shroud fixing structure for a turbine blade that reduces the tenon crimping man-hour while maintaining the shroud and tenon stresses at appropriate values, as described in Patent Document 2. .

JP-A-8-93401 JP 11-280405 A

  In the joint structure of tenon and shroud, high local stress is applied due to centrifugal load and blade vibration load near the contact end with the shroud at the base of the radius of the tenon due to the high contact surface pressure due to the caulking of the tenon. It turns out that there is a possibility.

  Furthermore, when the corrosion environment conditions become severe due to the concentration of trace corrosion products contained in the steam due to the long-term operation of the turbine rotor blade, fatigue cracks may occur at the above-mentioned positions. I know that.

  However, in the prior art, there is no mention regarding such a technical problem.

  Therefore, in the present invention, the vibration stress in the vicinity of the contact end described above is reduced with respect to the vibration of the turbine blade, and the concentration of the corrosion product is suppressed, thereby improving the reliability of the tenon / shroud joint structure. Turbine blades are provided.

  A turbine blade group according to an embodiment of the present invention is configured to connect a turbine blade and a shroud by passing a tenon provided at a tip of the turbine blade through a tenon hole of the shroud and caulking the tenon. . Then, at least a part of the radially inner peripheral end surface of the shroud is formed around the tenon so as to be in contact with the blade shoulder of the turbine blade.

  A plurality of tenons are provided at the tip of one turbine blade.

  The height (h) of the shroud on the inner circumferential side of the inner circumferential side is formed to be larger than the distance (d) from the parallel portion, which is the contact position between the tenon and the shroud, to the inner circumferential side of the shunt.

  Further, the turbine rotor blade is formed larger than the distance (d) from the parallel portion, which is the contact position between the tenon and the shroud, to the inner circumferential side chanha end in the rotational direction. The height (h) of the shroud on the radially inner side of the shroud is formed larger than the inner peripheral side radius (R) of Tenon.

  Furthermore, the turbine rotor blade group which is one embodiment of the present invention is to connect the turbine rotor blade and the shroud by passing the tenon provided at the tip of the turbine rotor blade through the tenon hole of the shroud and deforming the tenon. Then, around the tenon, at least a part of the inner peripheral side end surface of the tenon hole formed in the shroud is formed so as to contact the blade shoulder of the turbine blade.

  Further, it is preferable that the blade shoulder width in the rotational direction of the turbine rotor blade is formed larger than the maximum diameter portion of the tenon hole formed in the shroud.

  Further, the blade shoulder of the turbine blade contacting the tenon hole formed in the shroud on the radially inner end surface of the shroud is the blade shoulder in the rotational direction of the turbine blade.

  In addition, it is preferable that at least a part of the radially inner peripheral side end surface of the shroud is formed so as to be in contact with the blade shoulder of the turbine rotor blade on the entire circumference around the tenon.

  The turbine rotor blade as described above is preferably used for a steam turbine.

  In addition, the shroud formed so as to be in contact with the turbine rotor blade according to the embodiment of the present invention has at least a part of the radially inner peripheral end surface of the shroud around the tenon, and the blade shoulder of the turbine rotor blade. It is formed so as to come into contact with. In other words, it is possible to apply such a device to at least one turbine blade of the turbine blade group, and it is also possible to apply such a device to at least one of the tenons in one turbine blade. is there.

  The present invention reduces the vibration stress in the vicinity of the contact end described above with respect to the vibration of the turbine blade, and suppresses the concentration of corrosion products, thereby improving the reliability of the combined structure of the tenon and the shroud. A moving blade can be provided.

  An embodiment of the present invention will be described with reference to FIG.

Two tenons 2a and 2b on the steam inlet side and the steam outlet side are integrally formed with the turbine rotor blade 1 at the tip of the turbine rotor blade 1 in the steam inflow direction. Each tenon 2a,
2b is deformed by being caulked through a tenon hole provided in the shroud 3, and a predetermined surface pressure is applied between the tenons 2a and 2b and the shroud 3 for connection. Thus, the turbine rotor blade 1 and the shroud 3 are connected. In addition, although the present Example shows the case where there are two tenons, three may be used.

  FIG. 1 (b) shows the shape of the tenon 2b on the steam outlet side in the blade thickness direction (BB cross section in FIG. 1 (a)).

  The root of the tenon 2 in the turbine blade 1 is provided with an arc 4 having a predetermined radius of curvature (R) in order to reduce stress concentration.

  The tenon hole of the shroud 3 is composed of an outer peripheral side chamber 5, a parallel portion 6, and an inner peripheral side chamber 7 with respect to the radial direction of the shroud 3, and the surface pressure between the tenon 2 and the shroud 3 is It is transmitted by the side chanha 5 and the parallel part 6.

  A feature of this structure is that a contact area (width) e is secured between the inner peripheral side end face 12 of the shroud 3 and the blade shoulder 13. In addition, the position which ensures a contact area between the shroud inner peripheral side end surface 12 and the blade shoulder 13 is not limited to this cross-sectional position, and is preferably applied all around the tenon.

  The contact area e between the inner peripheral side end face 12 of the shroud 3 and the blade shoulder 13 includes the deformation amount of the inner peripheral corner S of the shroud 3 due to the caulking deformation of the tenon 2 and the assembly tolerance of the initial tenon hole and the tenon 2. In view of this, it is desirable to secure 0.5 mm or more in order to obtain the effect of this embodiment. However, if this width is too large, the turbine rotor blade 1 also becomes heavy, which affects other characteristics. Therefore, it is preferably 1.5 mm or less.

  As shown in FIG. 1 (b), the shape of the inner peripheral side chunk 7 of the shroud 3 is set so that the inner peripheral side chunk height (h) of the shroud 3 is changed from the parallel portion 6, which is the contact position with the tenon 2, to the inner circumference. It is formed larger than the length (d) to the side Changha corner (S).

  With this structure, under the condition where the length (d) is the same, in the stress concentration portion which is the contact end between the tenon 2 and the shroud 3, the base radius (Q) of the root of the tenon 2 and the shroud 3 By separating the distance from the contact end (P) with the tenon 2, the stress concentration against centrifugal force and blade vibration can be reduced.

  Under the condition where the length (d) and the radius of curvature (R) of the tenon 2 are equal, the height of the inner circumferential side of the shroud 3 (h) and the radius of curvature (R) at the root of the turbine rotor blade 1 FIG. 4 shows the relationship of the local maximum stress at the contact end (near) 15 between the tenon 2 and the shroud 3 with respect to the ratio.

  In FIG. 4, the local maximum stress at h / R = 1 is standardized as 1. As shown in FIG. 4, by securing h / R of 1.2 or more, an effect of reducing the local stress at the contact end 15 between the tenon 2 and the shroud 3 by about 5% can be expected. However, if h / R is increased too much, the parallel portion 6 that is a region responsible for the surface pressure between the tenon 2 and the shroud 3 and the outer peripheral side chamber 5 may become small, and the contact surface pressure may become excessively high. Therefore, h / R is preferably 1.5 or less.

  Further, it is desirable that the length (d) is 1.0 R or more in order not to interfere with the radius of curvature (R) of the base of the tenon 2.

Further, for example, in the structure in which the height (h) of the inner circumferential side chanha 7 and the distance (d) from the parallel portion 6 to the inner circumferential side chanha corner (S) are formed to be equal, the blade shoulder 13 on the entire circumference of the tenon 2. When the contact region e is to be secured on the inner peripheral side end face 12 of the shroud 3, the blade width of the turbine rotor blade 1 is formed to be excessively large, particularly when viewed from the blade thickness direction cross-section of the tenon 2b on the steam outlet side. There may be a need.

  In that case, it is assumed that a problem of an increase in centrifugal force or a decrease in performance due to an increase in the weight of the turbine rotor blade 1 occurs.

  Therefore, by forming the length (d) to be smaller than the inner circumferential side height (h) as in the present embodiment, the blade shoulder 13 and the inner circumferential side end face 12 of the shroud 3 around the tenon 2 are provided. By applying the present embodiment in which a part of the turbine rotor blade 1 is brought into contact, an effect of suppressing the increase in the weight of the turbine rotor blade 1 that is generated can be obtained.

  In general, the longer the turbine blade 1, the lower the natural frequency and the lower the excitation order, so that the vibration response due to blade vibration increases. Further, it is known that when the paragraph temperature is in the range of 50 ° C. to 200 ° C., the concentration of corrosion products contained in a trace amount in the steam proceeds.

  Therefore, it is desirable to apply to a range in which the blade length is 200 mm or more and the paragraph temperature is 50 ° C. to 200 ° C. as conditions where both factors of blade vibration and corrosive environment become severe.

  Around the tenon 2, at least a part of the inner peripheral side end surface of the shroud 3 and the blade shoulder 13 are brought into contact with each other, whereby a part of the load transmitted by the blade vibration is dispersed in the blade shoulder 13. Thereby, the effect of reducing the vibration load transmitted to the tenon 2 is obtained.

  Furthermore, the effect of reducing the concentration of corrosion products can be expected by suppressing the inflow of steam to the root of the tenon 2 which is a high stress concentration part.

  Further, by forming the inner peripheral side height of the shroud 3 in the radial direction to be larger than the distance from the contact position between the tenon 2 and the shroud 3 to the end of the chanha, the curvature radius bottom of the base of the tenon 2 and the shroud 3 This has the effect of reducing the stress concentration at the contact end. Further, when the inner peripheral side end face of the shroud 3 and the blade shoulder 13 are brought into contact with each other around the tenon 2, an effect of suppressing the increase in the centrifugal force accompanying the increase in the weight of the turbine rotor blade 1 is also obtained.

  A comparative example of the present embodiment will be described with reference to FIG.

  The combined structure of the tenon and the shroud shown in the comparative example is such that the tenon 2 formed integrally with the turbine rotor blade 1 is passed through the tenon hole of the shroud 3 at the tip of the turbine rotor blade 1 and the tenon 2 is caulked to be plastically deformed. By doing so, a predetermined surface pressure is applied and coupled between the tenon 2 and the shroud 3.

  In the contact portion between the shroud 3 and the tenon 2, the following are taken into consideration in consideration of reduction of the generated stress and prevention of cracking due to caulking.

  The tenon hole of the shroud 3 is formed in the radial direction of the shroud 3 from the outer peripheral side chunk 5, the parallel part 6, and the inner peripheral side chunk 7. The outer peripheral side changer 5 has an appropriate dimension for preventing the occurrence of caulking cracks due to strain concentration during caulking of the tenon 2.

  In order to apply an appropriate surface pressure on the contact surface between the tenon 2 and the shroud 3, the dimensions of the parallel portion 6 of the shroud 3 and the outer peripheral side chamber 5, which are the regions in contact with the contact surface pressure, are determined. An appropriate radius of curvature 4 is provided at the base of the tenon 2 so as to relieve stress concentration, and the inner peripheral side chanha 7 of the shroud 3 is formed so as not to interfere with the radius of curvature 4 of the base of the tenon 2. Has been.

  In the structure of the comparative example, the height (h) of the inner peripheral side chamber 7 and the distance (d) from the parallel portion 6 that is the contact position between the tenon 2 and the shroud 3 to the inner peripheral side end (S) of the shroud 3 (d) ) Are formed almost equally.

  Further, since the blade thickness generally decreases as it is located on the steam outlet side of the turbine rotor blade 1, the inner circumferential side end face 12 of the shroud 3 and the blade shoulder 13 do not contact with each other in the blade thickness direction cross section of the tenon 2. Existed.

  At the contact portion between the tenon 2 and the shroud 3, a high surface pressure close to the yield stress of the material acts, and in the vicinity 15 of the contact end with the shroud 3 at the bottom of the radius of curvature at the root of the tenon 2, centrifugal load and blade vibration High local stress may occur with respect to the load. Further, when a corrosion product contained in a trace amount in the steam is concentrated in the stress concentration portion between the tenon 2 and the shroud 3 due to a long-term operation, the contact between the tenon 2 and the shroud 3 is caused by a decrease in fatigue strength due to the corrosive environment. There was a possibility that a fatigue crack occurred from the end vicinity 15.

  FIG. 3 shows a schematic deformation diagram with respect to blade vibration and the flow of load, and the effect of this embodiment will be described.

  3 (b) and 3 (c) show the shape of the tenon 2b on the steam outlet side in the blade thickness direction (BB cross section in FIG. 3 (a)). Reference numeral 2a denotes a tenon on the steam inlet side.

  In the case of the comparative example in which the inner peripheral side end face 12 of the shroud 3 is not in contact with the blade shoulder 13 in the cross section in the blade thickness direction, the load flow line due to blade vibration from the shroud 3 is shown in FIG. Is transmitted directly to the tenon 2.

  On the other hand, as shown in FIG. 3C, in the case of the present embodiment, a structure in which a part of the inner peripheral side end face 12 of the shroud 3 and the blade shoulder 13 are brought into contact with each other around the tenon 2. In order to employ, by restraining the shroud 3 and the blade shoulder 13 to contact each other, the amount of deformation due to blade vibration is reduced, and a part of the vibration load 20 transmitted from the shroud 3 is transmitted to the blade shoulder 13. The load acting on the tenon 2 can be reduced.

  As a result, compared to the case shown in FIG. 3B, the case shown in FIG. 3C has the effect of reducing the generated stress in the high stress concentration portion 15 near the contact end 15 between the tenon 2 and the shroud 3. can get.

  The contact surface pressure of the blade shoulder 13 varies due to caulking, and the contact surface is deformed in the direction in which the clearance between the inner peripheral side end surface 12 of the shroud 3 and the blade shoulder 13 increases due to the centrifugal force of the shroud 3. Since the pressure tends to decrease, it is assumed that the stress reduction effect varies.

  According to the test and analysis by simulation of the structure of Tenon 2, compared with the structure of the comparative example, the structure shown in this example can be expected to have a vibration stress reduction effect of about 20 to 50%.

In the structure of the comparative example, as shown in FIG. 3 (b), the steam 21 enters from the gap between the inner peripheral side end face 12 of the shroud 3 and the blade shoulder 13, and the stress at the contact end between the tenon 2 and the shroud 3. It is assumed that the corrosion products are concentrated at the concentrated portion and the fatigue strength is lowered. However, in the structure of the present embodiment, as shown in FIG. 3C, the gap between the inner peripheral side end face 12 of the shroud 3 and the blade shoulder 13 can be closed all around the tenon 2. The effect of reducing the concentration of corrosion products by suppressing the inflow of steam into the base of the can also be expected.

It is the figure which showed the present Example. (A) is a bird's-eye view, (b) is BB sectional drawing in (a). It is a figure explaining the structure of tenon and shroud by the structure of a comparative example. It is the schematic diagram which showed the effect by this invention qualitatively. (A) is a bird's eye view, (b) is a BB sectional view in (a) according to the structure of a comparative example, and (c) is a BB sectional view in (a) according to the present embodiment. It is explanatory drawing which showed the effect of a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Turbine rotor blade, 2 ... Tenon, 3 ... Shroud, 4 ... Arc, 5 ... Outer peripheral side chanha, 6 ... Parallel part, 7 ... Inner peripheral side chanha, 12 ... Shroud inner peripheral side end surface, 13 ... Blade shoulder, 15 ... Tenon and shroud contact end (near), 20 ... Load flow line due to blade vibration.

Claims (10)

In the turbine blade group that connects the turbine blade and the shroud by passing the tenon provided at the tip of the turbine blade through the tenon hole of the shroud and caulking the tenon,
A turbine rotor blade group around the tenon, wherein at least a part of a radially inner peripheral side end surface of the shroud is formed so as to contact a blade shoulder of the turbine rotor blade.   The turbine blade group according to claim 1, wherein a plurality of tenons are provided at one tip of the turbine blade.   The height (h) of the radially inner circumferential chanha of the shroud is formed to be larger than the distance (d) from the parallel portion, which is the contact position between the tenon and the shroud, to the inner circumferential chanha end. The turbine rotor blade group according to claim 1, wherein In the turbine blade group that connects the turbine blade and the shroud by passing the tenon provided at the tip of the turbine blade through the tenon hole of the shroud and deforming the tenon,
A turbine motion around the tenon, wherein at least a part of an inner peripheral side end surface of a tenon hole formed in the shroud is formed so as to contact a blade shoulder of the turbine blade. Wings group.   A steam turbine having the turbine rotor blade according to claim 1. In the turbine blade group that connects the turbine blade and the shroud by passing the tenon provided at the tip of the turbine blade through the tenon hole of the shroud and deforming the tenon,
A turbine rotor blade group, wherein a blade shoulder width in a rotation direction of the turbine rotor blade is formed larger than a maximum diameter portion of a tenon hole formed in the shroud.   The blade shoulder of the turbine blade contacting the tenon hole formed in the shroud at the radially inner peripheral end surface of the shroud is a blade shoulder in the rotational direction of the turbine blade. Turbine blade group.   2. The turbine rotor blade according to claim 1, wherein the turbine rotor blade is formed to have a rotational direction larger than a distance (d) from a parallel portion, which is a contact position between the tenon and the shroud, to an inner circumferential end of the shaft. The turbine rotor blade group described.   2. The turbine rotor blade group according to claim 1, wherein a height (h) of a radially inner circumferential side of the shroud is formed to be larger than an inner circumferential side radius (R) of the tenon. 2. The turbine motion according to claim 1, wherein at least a part of a radially inner peripheral end surface of the shroud is formed so as to be in contact with a blade shoulder of the turbine rotor blade on the entire circumference of the tenon. Wings group.

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