JP2001248404A - Moving blade of turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine moving blade capable of preventing occurrence of damage or stress concentration causing the damage by certainly keeping a connection force of an annular blade row and suppressing partial contact of a blade groove provided on the outer periphery of a rotor with a dovetail during turbine operation. SOLUTION: The turbine moving blade comprises the dovetails 2 pressed into the blade grooves 8 formed on the outer periphery of a disk 6 of the rotor 7, blade parts 3 extending from the dovetails 2, and integral shrouds 4 at the upper ends of these blade parts 3, and the integral shrouds 4 are interconnected to form the annular blade row. A circumferential end surface of each integral shroud 4 is provided with mutually overlapping projections 4a, 4b having a gradient in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine rotor blade which is embedded in a blade groove formed on the outer periphery of a rotor of a turbine to form an annular cascade.

[0002]

2. Description of the Related Art An axial flow bin is provided with turbine rotor blades which are embedded in blade grooves formed on the outer periphery of a disk of a rotor to form an annular cascade, and stationary blades which form a stage with the turbine rotor blades. Fluid flowing out of the turbine is sprayed on turbine blades to rotate the rotor and generate power.

[0003] As one of such turbine blades, for example, Japanese Patent Laid-Open Publication No. 7-145701 discloses a dovetil embedded in a disk of a rotor, a blade extending from a blade root, and an integral covering an upper end of the blade. The turbine blades are provided with a shroud and are integrally cut.The surfaces where adjacent integral shrouds contact each other are provided with step portions in the thickness direction. A turbine rotor blade is described in which the distance to the lower surface of the step is set longer than the distance from the contact point between the rotor and the dovetail to the upper surface of the step portion.

[0004]

In the turbine blade of the annular cascade configured as described above, the connection structure is maintained by the processing accuracy, but the connection force between the adjacent blades is sufficiently maintained. Consideration is needed. If the difference between the distance from the contact point between the rotor and the dovetail to the lower surface of the step portion and the distance to the upper surface is set to be long in order to maintain a sufficient coupling force to obtain the vibration damping effect, assembly becomes difficult. And by increasing the difference in the distance,
There is a possibility that the contact between the blade groove formed on the outer periphery of the rotor and the dovetail is not a surface contact, but a one-sided state, a portion where stress is concentrated on the dovetail or the blade groove.

SUMMARY OF THE INVENTION It is an object of the present invention to reliably hold a connecting blade of an annular cascade during operation of a turbine and to suppress breakage of a blade groove formed on the outer periphery of a rotor and a dovetail to prevent breakage. An object of the present invention is to provide a turbine rotor blade.

[0006]

In order to achieve the above object, a turbine blade according to the present invention is provided with a dovetil inserted into a blade groove formed on an outer periphery of a rotor, and a dovetail extending from the dovetil. In a turbine rotor blade having a blade portion and an integral shroud at an upper end of the blade portion, and connecting the integral shroud to form an annular cascade,
On the circumferential end face of the integral shroud, there are provided projections which have a slope with respect to the axial direction and are superposed on each other in a structure in which they are in radial contact with each other.

More specifically, the abdominal circumferential end face of the projection has a slope cut from the outer circumference, and the dorsal circumferential end face of the projection has a slope cut from the inner circumference. It is.

More specifically, the abdominal circumferential end face and the dorsal circumferential end face of the projection are stepped.

More specifically, a key groove is formed between the lower part of the dovetail and the blade groove, and a key is inserted into the key groove.

In order to achieve the above object, another aspect of the turbine blade according to the present invention includes a dovetil pushed into a blade groove formed on the outer periphery of the rotor, a blade extending from the dovetil, An integral shroud at the upper end of the blade portion, and in a turbine rotor blade forming an annular cascade by connecting the integral shrouds, a circumferential end face of the integral shroud has a gradient with respect to an axial direction. The projection has a structure in which the projections overlap with each other in a structure in which the projections are in surface contact with each other in the radial direction. The end face has a stepped shape with a slope cut from the inner peripheral side, and a key groove is formed between the lower part of the dovetail and the wing groove, and a key is inserted into the key groove.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turbine rotor blade according to the present invention will be described below with reference to the drawings. FIG. 1 is a partial perspective view of an annular cascade in which a turbine blade according to a first embodiment of the present invention is embedded in a disk of a rotor, and FIG. 2 is a perspective view of a turbine blade alone. FIG. 3 is an action diagram of a force acting on the integral shroud of the turbine rotor blade.

In FIGS. 1 and 2, the turbine blades 1, 1
′ Comprises a wing portion 3 extending from a dovetil 2 embedded in a disk 6 of a rotor (see FIG. 4) and an integral shroud 4 covering the upper end of the wing portion 3. Reshroud 4 is cut out as one piece. In addition, integral shroud 4
Projecting portions 4a, 4b overlapping each other
The projection 4a on the abdominal circumferential end face of the turbine blade 1 is shaped like a step with a slope cut from the outer peripheral side, and the projection 4b on the back circumferential end face of the turbine blade 1 'is It is shaped like a step with a slope cut from the inner circumference.

The turbine blades 1 'are inserted into the blade grooves 8 formed in the axial direction on the outer periphery of the disk 6 provided on the rotor.
Then, by embedding the turbine blade 1 in the remaining blade groove 8, the protrusions 4 a and 4 b on the circumferential end surfaces of the adjacent integral shrouds 4 come into radial contact with each other. An annular cascade is formed by overlapping and touching the structure. A groove is formed in the upper part of the disk 6,
The key 5 is inserted between the lower part of the dovetail 2 and the wing groove 8.

FIG. 3 shows the forces acting between adjacent integral shrouds 4 when an annular cascade is formed in the turbine rotor blade having the above-described configuration. When every other turbine blade 1 is embedded in the blade groove 8, the protrusion 4 b on the circumferential end face of the integral shroud 4 of the left and right turbine blades 1 ′ in FIG. The radially outward force Ft is received from the protrusion 4a on the direction end surface, and the turbine blade 1 'is in a state of lifting. Conversely, the protrusion 4a on the circumferential end face of the integral shroud 4 of the turbine blade 1 generates a radially inward force Ft from the protrusion 4b on the circumferential end face of the integral shroud 4 of the turbine blade 1 '. As a result, the turbine blade 1 is pushed.

For this reason, the inner peripheral surface of the blade groove 8 of the disk 6 and the outer peripheral surface of the dovetail 2 are forcedly brought into surface contact. Similarly, both the outer peripheral surface of the dovetil 2 of the turbine rotor blade 1 and the inner peripheral surface of the blade groove 8 of the rotor 7 have a surface formed by inserting the key 5 between the lower portion of the dovetail 2 and the blade groove 8. It comes to contact. F indicates a force that the projections 4a and 4b of the turbine rotor blades 1 and 1 'exert on each other in the circumferential direction.

As described above, according to the present embodiment, the theory is achieved by alternately inserting the turbine blades 1 and 1 'into the blade grooves 8 formed in the disk 6 of the rotor and overlapping the projections 4a and 4b. When forming an annular cascade in which turbine rotor blades are embedded at a pitch, by adjusting the inclination provided on the projections 4a and 4b, it is possible to connect the adjacent blades at the time of embedding while maintaining an appropriate surface pressure. It is possible to reduce the vibration by maintaining the vibration damping effect, and to prevent the occurrence of stress concentration leading to breakage or breakage of the turbine blade.

Further, by inserting the key 5 between the lower part of the dovetil 2 and the blade groove 8, the dovetil 2 and the blade groove 8 can be surely brought into surface contact with each other. It is possible to prevent the wing from being damaged or the stress concentration leading to the damage.

FIG. 4 shows a second embodiment of the turbine rotor blade according to the present invention.
1 is a partial perspective view of an annular cascade in which turbine blades are embedded in a rotor disk in the embodiment. In the present embodiment, when the turbine blade 1 is greatly affected by centrifugal force, the outer peripheral surface of the dovetail 2 and the inner peripheral surface of the blade groove 8 are surely brought into surface contact by the centrifugal force of the turbine blade 1. This makes it unnecessary to insert the key 5. The turbine blades 1 'are also embedded in the disk 6 alternately with the turbine blades 1 as in the first embodiment, but are not shown in the drawing.

According to the present embodiment, since the key is not required to be inserted, the processing of the key groove in the disk becomes unnecessary, and the structure for embedding the turbine blade can be simplified.

[0020]

According to the present invention, during turbine operation, the connecting cap between the annular blade cascades is securely held, and the blade groove formed on the outer periphery of the rotor disk and the dovetail are prevented from coming into contact with each other, thereby damaging the rotor. Alternatively, it is possible to provide a turbine rotor blade capable of preventing occurrence of stress concentration leading to breakage.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an annular cascade in which a turbine rotor blade according to a first embodiment of the present invention is embedded in a disk of a rotor.

FIG. 2 is a perspective view of the turbine blade of FIG. 1 alone.

FIG. 3 is an action diagram of a force acting between integral shrouds of a turbine rotor blade.

FIG. 4 is a second embodiment of the turbine bucket according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Turbine rotor blade 1 '... Turbine rotor blade 2 ... Dovetail 3 ... Blade part 4 ... Integral shroud 4a, 4b ... Projection part 5 ... Key 6 ... Disk 7 ... Rotor 8 ... Blade groove

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kiyoshi Namura 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Electric Power and Electric Development Laboratory, Hitachi, Ltd. 3G002 DA01 FA04 FB06

Claims (5)

[Claims] 1. A rotor having a dovetil pushed into a blade groove formed on the outer periphery of a disk of a rotor, a wing extending from the dovetil, and an integral shroud at an upper end of the wing, and connecting the integral shroud. In the turbine rotor blade constituting the annular blade cascade, the circumferential end face of the integral shroud is provided with a projection that has a slope with respect to the axial direction and overlaps each other in a structure that makes a surface contact in the radial direction. Turbine blade. 2. An abdominal circumferential end face of the protrusion has a slope cut from an outer peripheral side, and a dorsal circumferential end face of the protrusion has a slope cut from an inner circumferential side. The turbine blade according to claim 1, wherein: 3. The turbine rotor blade according to claim 2, wherein an abdominal circumferential end face and a dorsal circumferential end face of the protrusion are stepped. 4. The turbine rotor blade according to claim 1, wherein a key groove is formed between the lower part of the dovetail and the blade groove, and a key is inserted into the key groove. 5. A rotor having a dovetil pushed into a blade groove formed on an outer periphery of a disk of a rotor, a wing extending from the dovetil, and an integral shroud at an upper end of the wing, and connecting the integral shroud. A turbine rotor blade forming an annular blade cascade, wherein a circumferentially end surface of the integral shroud is provided with projections that have an inclination with respect to an axial direction and overlap with each other in a structure in which they are in radial contact with each other; The abdominal circumferential end face has a stepped shape having a slope cut from the outer circumferential side, and the dorsal circumferential end face of the projection has a stepped shape having a slope cut from the inner circumferential side. A turbine rotor blade having a key groove formed between a lower part and a blade groove, and a key is inserted into the key groove.