JPH10252402A - Stress reduction disc - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the stress generated in a disk, increase the allowable rotation speed even when the number of blades is small, and reduce the weight of the disk. SOLUTION: An implantation groove for attaching a wing member is provided on an outer peripheral surface, and a plurality of stress reduction grooves extending in the thickness direction at intervals from the implantation groove are arranged at intervals in the circumferential direction. The bottom of the stress reducing groove has an arcuate cross-sectional shape, the bottom and the side of the stress reducing groove are connected by a smooth continuous surface, and the circumferential width of the stress reducing groove extends from the outer peripheral surface of the disk toward the bottom. The radius of the disk decreases toward the portion where the implantation groove is not formed, and is slightly larger than the portion where the implantation groove is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stress reducing disk, and more particularly to a technique suitable for fixing a wing member to a rotating shaft.

[0002]

2. Description of the Related Art FIG. 3 shows a "turbine rotor blade" described in Japanese Patent Application Laid-Open No. 7-12740.

In FIG. 3, reference numeral 1 denotes a turbine blade, 2
Is a disk, 3 is an implantation groove, 4 is a blade root, and 5 is a blade.

When the disk 2 rotates, a radially outward force is applied to the blade root portion 4 due to the inertia force at the time of rotation and the centrifugal force acting on the turbine rotor blade 1, and the circumferential direction is applied to the implant groove 3. Stress has occurred.

[0005]

However, when the number of turbine blades 1 implanted in the disk 2 is large, there occurs a phenomenon in which the circumferential stresses are canceled out by the centrifugal force of the adjacent blade roots 4. However, when the number of turbine blades 1 is small, the above-described canceling phenomenon disappears, and the allowable rotation speed cannot be increased. There is also a method of reducing the stress by attaching a dummy blade when the number of moving blades is small, but it is disadvantageous because the weight increases.

The present invention has been made in view of the above circumstances, and aims to achieve the following objects. To reduce the stress generated on the disk. Increase the permissible rotation speed even when the number of blades is small. Eliminate the need to install dummy wings. Reduce the weight of the disc.

[0007]

SUMMARY OF THE INVENTION A disk for rotating a wing member together with a shaft is provided with an implant groove for mounting the wing member on an outer peripheral surface of the disk, and is spaced apart from the implant groove. Stress reducing grooves are provided in the thickness direction to reduce stress concentration. A plurality of stress reducing grooves are arranged at intervals in the circumferential direction. The bottom of the stress reduction groove has an arc-shaped cross section, and the bottom and the side surface of the stress reduction groove are connected by a smooth continuous surface. The circumferential width of the stress reducing groove decreases from the outer peripheral surface of the disk toward the bottom. The radius of the disk at the portion where the implantation groove is not formed is made slightly larger than that at the portion where the implantation groove is formed in order to balance the weight.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a stress reduction disk according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes a stress reducing disk, 10a denotes an outer peripheral surface, 11 denotes a stress reducing groove, 12 denotes a bottom portion, 12a denotes a side surface,
3 is an implantation groove (dovetail groove), 14 is a radius increasing portion, 15
Is a radius reduction part.

As shown in FIG. 1, the stress reducing disk 10 is a disk for rotating the wing member together with the shaft and is formed in a disk shape. A plurality of stress reduction grooves 11 are provided in the thickness direction at intervals from the dovetail groove 13 to reduce stress concentration.

As shown in FIG. 1, a plurality of, for example, eight, stress reducing grooves 11 are arranged at intervals in the circumferential direction.
2 and the side surface 12a are formed. For example, two dovetail grooves 13 are arranged, and as shown in FIG. 1, have a curved shape in accordance with the shape of the wing member.

The dovetail groove 13 is used for the stress reducing disc 10
The stress reducing groove 11 is arranged at a symmetrical position on the circumference of
Every time. It is arranged at intervals of 50 degrees and 40 degrees.

The bottom portion 12 of the stress reducing groove 11 has an arc-shaped cross section, and as shown in FIG. 1, the bottom portion 12 and the side surface 12a are connected by a smooth continuous surface, and the side surface 12a has an inclination. The circumferential width of the reduction groove 11 is configured to decrease from the outer peripheral surface 10 a of the stress reduction disk 10 toward the bottom 12.

The radius of the disc where the dovetail groove 13 is not formed is slightly larger than the portion where the dovetail groove 13 is formed in order to balance the weight, and the radius increasing portion 14 is formed. In the outer peripheral surface 10a of the stress reducing disk 10, the portion where the dovetail groove 13 is disposed is a radius reducing portion 15 up to the stress reducing grooves 11 on both sides, and the radius of the stress reducing disk 10 is reduced.

The stress reducing disk 10 having such a structure
Is attached to the dovetail groove 13 by embedding a wing member having a blade root having a shape corresponding to the dovetail groove 13 in a state fixed to the rotation axis A, and rotating the rotation axis A. The torque is transmitted to the wing member.

At this time, a circumferential stress is generated in the dovetail groove 13 due to the inertial force of the wing member and the centrifugal force acting on the wing member. The angle between the outer peripheral surface 10a and the side surface 12a is an obtuse angle. Further, since the surface shape between the side surface 12a and the bottom portion 12 is a smooth continuous surface, the generated stress is reduced without causing stress concentration. Therefore, the maximum stress generated in the stress reducing disk 10 due to the formation of the stress reducing groove 11 can be reduced. By forming the radius increasing portion 14, the weight balance can be improved.

A member attached to the dovetail groove 13 can be attached other than a wing member, and the number of the dovetail grooves 13 can be three or more. Further, it can be used in a rotation test of a turbine blade of a gas turbine engine or the like.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a stress analysis performed on a stress reduction disk according to the present invention will be described below.

The stress reducing disk 10 has the following specifications. Diameter 600 mm Thickness 65 mm Disk rotation speed 21000 rpm The disk shape was made axially symmetric, and analysis was performed using only the quadrant.

As a result, a stress distribution diagram shown in FIG. 2 was obtained.
Here, the generated maximum stress is 1280 MPa. The maximum stress generated in a disk having a circular cross section without a stress reducing groove is 1930 MPa, and the dovetail groove 1
The maximum stress that occurred in a case where a number of 3 were arranged and no dummy wing was attached was 2440 MPa.

Therefore, the result of the stress analysis shown in FIG.
The stress reduction was 33.7% as compared with a disk having a circular cross section, and 47.5% as compared with a disk having a large number of dovetail grooves 13.

[0021]

According to the stress reduction disk of the present invention, the following effects can be obtained. (1) Since the stress reducing groove is provided, the stress generated in the disk can be reduced. (2) By reducing the generated stress, the allowable rotation speed can be increased even when the number of blades is small. (3) Since there is no implantation groove to which the wing member is not attached, the necessity of assembling the dummy wing can be eliminated. (4) Since the volume of the disk is reduced by providing the stress reduction groove, the weight of the disk can be reduced.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing one embodiment of a stress reduction disk according to the present invention.

FIG. 2 is a stress distribution diagram showing an analysis result of a stress distribution in a stress reduction disk according to the present invention.

FIG. 3 is a perspective view showing a conventional disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Stress reduction disk 10a ... Outer peripheral surface 11 ... Stress reduction groove 12 ... Bottom 12a ... Side surface 13 ... Implantation groove (dovetail groove) 14 ... Radius increasing part 15 ... Radius decreasing part

Claims (5)

[Claims] An implant groove (13) for attaching a wing member is arranged on an outer peripheral surface (10a), and a stress reducing groove (11) is arranged in the thickness direction at an interval from the implant groove. A stress reduction disk characterized by the following. 2. The stress-reducing disk according to claim 1, wherein a plurality of stress-reducing grooves are arranged at intervals in the circumferential direction. 3. A bottom portion (12) of the stress reducing groove (11) has an arc-shaped cross section, and a bottom portion and a side surface (12a) of the stress reducing groove.
3. The stress-reducing disk according to claim 1, wherein the two are connected by a smooth continuous surface. 4. The circumferential width of the stress reducing groove (11) is:
4. The stress-reducing disk according to claim 1, wherein the diameter of the disk decreases from the outer peripheral surface of the disk toward the bottom. 5. The stress reduction according to claim 1, wherein a radius of the disc at a portion where the implantation groove (13) is not formed is set to be larger than that at a portion where the implantation groove is formed. disk.