US3627448A

US3627448A - Locking arrangement for side-entry blades

Info

Publication number: US3627448A
Application number: US889599A
Authority: US
Inventors: Donald R Rupp; James A Pratt
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1969-12-31
Filing date: 1969-12-31
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

An arrangement is provided for installing and subsequent locking of side-entry blades in a turbine rotor disc. Heretofore, the placement of the last blade in a circular row of turbine blades has required twisting, bending and distorting of the last and adjacent blade at assembly because of interference between adjacent blades. This jeopardized their reliability in service. The present arrangement permits radial entry of the last blade into the rotor or disc without distortion of any of the blades.

Description

United States Patent [72] Inventors DonlldlLRupp References Cited Media;

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369,127 3/1932 Great Britain................ 416/219 Primary Examiner- Everette A. Powell. .I r. H Attorneys-A. T. Stratton, F. P. Lyle and F. Cristiano. Jr.

ABSTRACT: An arrangement is provided for installing and [54] ARRANGEMENT FOR SIDE'ENTRY subsequent locking of side-entry blades in a turbine rotor disc. 4 Claims 4 Dnwin Fi Heretofore, the placement of the last blade in a circular row of 8 turbine blades has required twisting, bending and distorting of [52] US. the last and adjacent blade at assembly because of interference between adjacent blades. This jeopardized their reliability in service. The present arrangement permits radial entry of the last blade into the rotor or disc without distortion of any of the blades.

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[51] [50] Field of Search.

PAT ENTED on: I 4 ism LOCKING ARRANGEMENT FOR SIDE-ENTRY BLADES BACKGROUND OF THE INVENTION This invention relates, generally, to turbine rotors and, more particularly, to an arrangement for installing and securing turbine rotor side-entry blades in the periphery of a blade supporting disc.

During the construction of prior turbines, the placement of the last blade in a circular row of turbine rotor side-entry blades required twisting, bending and distortion of the last and adjacent blade at assembly because of interference between the blades. This distortion of the blades jeopardized their reliability duringoperation of the turbine.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, the lateral width of the platform portion of a turbine rotor sideentry blade which is to be installed last in the periphery of a rotor disc is reduced sufficiently to permit the blade to be inserted radially between the two adjacent blades without distortion of any of the blades. After the blade has been inserted to the bottom of the receiving channel, it is moved laterally to its operating position adjacent to the first blade installed and secured by means of a locking member which is inserted axially in a subchannel in the rotor disc. The locking member has a radially extending projection thereon which closed the space between the platforms of the last blade and the next to the last blade installed in a circular row of sideentry blades.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the nature of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawing, in which:

FIG. I is a diagrammatic view, partly in vertical section and partly in elevation, of a portion of a turbine rotor assembly embodying principal features of the invention;

FIG. 2 is an enlarged view, similar to FIG. 1, showing the last blade of a circular row of blades in its partly assembled position; and

FIGS. 3 and 4 are diagrammatic views, in plan, showing the manner of installing the last blade in a circular row of blades.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, particularly to FIG. I, there is shown a portion of a rotor 11 for an axial flow turbine of a type well known in the art. The rotor 11 comprises a disc 12 having a peripheral portion I3 with a plurality of axially extending serrated channels I4 circumferentially spaced around its periphery for receiving serrated root portions 15 of turbine rotor blades 16 of the side-entry type. In addition to the root portion I5, each blade 16 includes an airfoil portion 17 (partly shown) and a platform portion 18 joining the root portion to the airfoil portion. The serrations 19 on the channel 14 intermesh with the serrations 20 on the root portion 15 to withstand the centrifugal force developed by the rotation of the rotor and secure thev blade in the channel. After the blades are installed in the channels, keys (not shown) of a type well known in the art are utilized to prevent axial movement of the blades.

As shown in FIGS 3 and 4, the blades 16 may be provided with a lashing structure 6 of the type described in U.S. Pat. No. 2,472,886 issued June 14, 1949 to J. D. Conrad and W. H. Lloyd and assigned to Westinghouse Electric Corporation. The lashing structure includes projections 7 formed integrally with the airfoil portions 17 of the blades and extending outwardly with their outer ends disposed contiguously and connected, as by a welded joint located approximately midway between blades. The lashing structure reduces vibration of the blades.

0f the three blades 16 shown in FIG. 1, it may be assumed that blade 21 is the first one installed, blade 22 is next to the last one and blade 23 is the last one installed in a circular row of side-entry blades. I-Ieretofore, the installation of the last blade has required twisting, bending and distorting of the last and adjacent blade in order to insert the last blade into its channel from the side of the disc because of interference between adjacent blades as shown in FIG. 3. The distortion of the blades jeopardized their reliability in service.

In order to permit installation of the last blade without distortion of any of the blades, the lateral width of the platform portion 18a of the blade 23 is reduced sufficiently to permit the blade 23 to be inserted radially from above into its channel between

adjacent blades

21 and 22 as shown by dot-dash lines in FIGS. 2 and 4. In this manner, the last blade 23 can be installed without distortion of any of the blades.

After the blade 23 is inserted radially to the bottom of the channel 140, it is moved laterally to the right as viewed in FIG. 2 to the position shown in FIG. I and is secured in position by means of a locking member 25 which is inserted axially into a subchannel 24. The subchannel 24 has serrations 26 thereon which mesh with serrations 27 on the locking member 25 to secure it in the subchannel 24. Likewise, the locking member 25 has serrations 29 thereon which mesh with the serrations 20 on the root portions of the

blades

23 and 22 to maintain the blades in laterally spaced relation and secure the blades in their operating positions.

As shown in FIG. I, the locking member 25 has a radially extending projection 30 thereon which closes the space between the platform portions 18 and 18a of

adjacent blades

22 and 23, respectively. In this manner, leakage of the motive fluid between the platform portions is prevented. The locking piece 25 may be keyed in a manner similar to the blades 16 to prevent axial movement of the locking member during operation of the turbine.

From the foregoing description, it is apparent that the invention provides a locking arrangement which permits the installing and subsequent locking of side-entry blades in a turbine rotor disc without distortion of any of the blades, thereby improving the reliability of the blades in service. The arrangement can be economically manufactured and utilized.

It will be noted by referring to FIG. I, especially, that the root portions of the next to last blade 22 and the last blade 23 are substantially identical to each other and to the root portion of the other blades as exemplified by blade 21. Also, the locking member 25 coacts with the rotor disc I2 to form two channels of identical configuration to the channel I4, thereby simplifying manufacturing of the blades and roots.

We claim as our invention:

1. In a locking arrangement for a circular row of turbine rotor side-entry blades,

said rotor having a disc with a plurality of axially extending channels circumferentially spaced around its periphery,

each blade having a root portion and an airfoil portion and a platform portion joining the root portion to the airfoil portion,

means on the root portion of each blade cooperating with means on a channel for securing the blade in the channel,

the lateral width of the platform portion of one of the blades being less than the lateral width of the platform portions of the other blades to permit said one blade to be inserted radially between two adjacent blades,

a locking member extending axially between said one blade and an adjacent blade to secure said one blade in its operation position, and

a radially extending projection on the locking member for closing the space between the platform portions of said one blade and an adjacent blade.

2. The locking arrangement defined in claim 1, wherein:

said rotor disc has an axially extending subchannel for receiving said locking member.

3. The locking arrangement defined in claim 2, including:

means on the locking member cooperating with means on the subchannel for securing the locking member in the subchannel. 4. The locking arrangement defined in claim 3, wherein: the locking member securing means includes intermeshing 5 serrations on the locking member and the subchannei.

II I l i

Claims

1. In a locking arrangement for a circular row of turbine rotor side-entry blades, said rotor having a disc with a plurality of axially extending channels circumferentially spaced around its periphery, each blade having a root portion and an airfoil portion and a platform portion joining the root portion to the airfoil portion, means on the root portion of each blade cooperating with means on a channel for securing the blade in the channel, the lateral width of the platform portion of one of the blades being less than the lateral width of the platform portions of the other blades to permit said one blade to be inserted radially between two adjacent blades, a locking member extending axially between said one blade and an adjacent blade to secure said one blade in its operation position, and a radially extending projection on the locking member for closing the space between the platform portions of said one blade and an adjacent blade.

2. The locking arrangement defined in claim 1, wherein: said rotor disc has an axially extending subchannel for receiving said locking member.

3. The locking arrangement defined in claim 2, including: means on the locking member cooperating with means on the subchannel for securing the locking member in the subchannel.

4. The locking arrangement defined in claim 3, wherein: the locking member securing means includes intermeshing serrations on the locking member and the subchannel.