US2386527A - Turbine rotor - Google Patents

Description

0. A. WIBERG I TURBINE ROTOR Oct, 9, 1945.

Filgd March 27, 1944 2 Sheets-Sheet 1 1945- o. A. WIBERG 2,386,527

7 TURBINE ROTOR Filed March 27, 1944 2 Sheets-Sheet 2 engagement withthose of the disc.

' Patented Oct. 9, 1 945 el i i e Wm" as Y 40mins. cuss-git);

Tasmanian relates to turbine rotors of the type-coinprising-a disc and a set of blades fixed to the periphery thereof. r a

In manufacturing turbinerotors of this type according to a well-known method, the blades engagement'between the base-portions, or feet,

of the blades and the peripheral portion of the are connected to the disc by means of a straddling disc, or vice versa, andsealed in this engagement by meansof peripherally extending claw-shaped projections, orlugs, formed on the contact surfaces of said feet which engage similar lugs formed on the contact surfaces of the peripheral" disc portion. The most usual way in which to effect this fixing of the blades to the supporting disc comprises deflecting the forked ends, or

prongs, of the blades or disc, causing the deflected prongs to straddle the peripheral portion of the disc or the blade feet, as the case maybe; and the associated lugs, and then forcing the prongs together so as to cause them to firmly embrace the member or members in engagement therewith. Since thismethod may giverise to certain risks'as to the-strength of the connection it has been proposed to fix the blades without deflecting the prongs of the forked mem-beror members."

Such a proposal is disclosed in the British Patent No. 461,058. According to said patent the lugs of the blade feet extend along a certainportion of the peripheral length of they blade feet only, whereas the annular projections or lugs of the peripheral portionof the disc are cut away at one or more places to an extent corresponding to the peripheral length of the lugsof the blade feet. Thus, at said place or each of said places an inlet passage will be obtained through which the bladefeet with their lugs may be. put onto. or inserted into the peripheral portionof the disc without requiring any deformation of the blade feet, nor of the disc. As soon as an-individual blade hasbeen mounted in this way, it has to be displaced peripherally so as to bringits lugs into The mounting of the lastblade being completed, all of the blades have to be pushed back around the disc byan amount corresponding -to the, peripheral length of the lugs of a blade foot in order that 7 also the last blade, the lugs of which extend from the opposite end of the blade foot as compared with the lugs of the other blades, may be adjusted to a position in which its lugs will engage the lugs of the disc. the lugs of the bladefeet extend along of the peripheral length of said feet. Consequently,

each individual blade may be sealed to the disc According to said patent along said of the:periphera1 length of the blades'ito-a -turbine-disc without deforming the blades,- nor the disc, has proved diflicult owing,

essentially; to the' said pushing back of the entire I set-of blades, resisted as itis by the high friction,

appearing 'b'etweenthe blade feet'and the periph- ;eral portion 1 of :the .-disc.- Furthermore, said method-cannot satisfactorily safeguard against a certain play within the blade ring.

lhe present in'vention' has for its object to facilitate. the fixing of the blades to the disc, .while positively avoiding anyplay between the blade feetand securing an increased strength and solidity of theblade ring as a whole.

The invention is characterized, chiefly, by the provision of a main group of blades having lugs extending alongv a portion only of the-peripheral length of -the feet from one end thereof, a minor group: Ofi blades having feet corresponding in position" and peripheral length to the respective lugs only, the'remainder of the feet having been cut away, an -additional .blade having a foot of the-same peripheral length as the said firstmentioned blades and lugs thereon extending along a portion of-theperiphera1 length of the foot from the 'oppo'site end-thereof as compared with the lugs of I said I first-mentioned blades, and means to' maintain the bladesof said minor group in predetermined positions with relation to each other-andto the said additional blade, said disc, having an inlet passage or passages to allow the applying of:the blades. to the periphery of the disc 1 i together to one side of the inlet passage within theirangez of the periphery of the disc available for the reception of these blades. By these means, the additional blade having reversely positioned lugs may be inserted through the inlet passage andzdisplaced peripherally to its final position on theyotherside of. the inlet passage into engagemerit with the lugs of the periphery of-the disc without: requiring the entire set of blades to be pushed back. Then, it is only required to move the blades of. the minor group apartpand fix them 'in' exact relative positions bymeans of distance pieces which correspond in size and form to the cutlaway portionsof the blade feet and like 'thes' have no lugs. It is preferred to make thedistance piece to'be la'st insertedtapered or wedge-shaped at its end, so that it maybe forced into its respective space in order to remove any ment of the invention is shown in Figs, 1 3, 5 and '7, which figures iilllistrat'e evarious' stages of ,the l assembling'of th'e turbine rotor the radius of which for the sake of simplicity may be assumedto be infinite and the periphery of which, as a result, may be represented by a straighttlified. i Figs. 2, 4, 6 and 8 show axial sections onithe 1 ines...15

II--II, IV-IV, VI-VI and VIII V'III, reap-ea: tively, of Figs. 1, 3, 5 and 7, reSPflCtivelMi-Eifiil 9*- shows a corresponding section of a modlfledreme bodiment. Figs. 2a, 4a, 6a and 6b are sectional views similar to Figs. 2, 4, 6 and 8 respectivelyof" aemodi-fied-rem-bodiment "10f: the.- :invention::.,

With referencecto theridrawings, thernumerahil; designates the peripheral pontiomof a turbineid-iso-iadapted: toc-be straddled-my, the forkashaped =feet of-wtheeturbine tbladeseto bevcarriedz thereby; It.

is. ;to :be noted. that. thearrangementgmambe re-$1 versed; ifl' desireda without: departing; fromithew principle of the invention. Sectional-mews core: responding .to Figs:-, .2, 2,6.anda-8wrespectivelyrbut showingythe reverse arrangement. in which? then: ,1;

turbine :d-isceisprovided with ther fork shapedr feet; which straddle-and grip;therroots10f:thetlturbinesblades; are ShOWn:in FigS:=2l1,-'iF1a;-5a and 6b; The

peripheral turbine:disc-:portion:icarries: onibothu of its; sides... ci-reumferentiallyyextendingu claw-9: g tanceepieces lisaeprovidedewith' lugsr. In .order;to=

shaped lugs. 12 .pointing,inwardlygtowardstlie axis: of the disc.:. These lugs areeishown in section Figi. .Zeandin' side-:elevation:=im Figzze .butzare-rfor the rest-merely indicatedin'Figsz 1 cbygdottedilines:

withinuthose: ranges :where {no :bladesgare shown-.2. -40;-,p1 iate'mean At:one: or more-2placesgtheylugs ;2..'.areecuti away? so aseto. fOPm'lanbIadQn inlet-passagesor. passages; extendinginthe direction;intendedforzthe blades-n. In" the =drawings,-.;.such an. inlet passage isjind'i 'j cated'sat: 3. As-shown;,saidyipassager extends; at; 5..

right: angles-ate the .=peripheryl Ofe thew. disc;: that i is tozsay; inwradial direction: If itherepiseblltione SllOhwpaSSagB, all theblades.rhave .to:v beeinserted .1 thereth-rough; inn order; however; to reduceethef:

necessaryflisplacement -of' each-blade: after inserr- .50

tion, it. is :prefer-redlto=provide-zarpluralityiof {inletn passages, say; ,four. Imsuch aacase. arfourthiofe. theiperipherygofl therdisc: may be filled withfl bladesthrough: each inlet passage.

Through'the'inletpassagezSsov each 'inletzpase 55,,

sage I first introduce a number of blades haw inggzfeet" ofi norma' type:- Thesebladesiform whatiis/referredtoias the mainzgroupof 'blades: in thiSEdBSCliptiOIIi Innthe case, illustratedethez peripheral length of the disc in order to permit the arrangement described. This arrangement having been obtained, the positions of the blades 4 of the main group with relation to the inlet passage 3 is the one illustrated in Fig. 1.

Then, I introduce through passage 3 the blades which are referred to as the minor group of blades. Said blades which are designated by the reference numeral 6, are few in number, say, three 'Iflieygare .fdrmedfwitl'r reducedrfeet, inasmucrfa the portions of the "feet not occupied by the lugs have been cut away. After insertion, the

"blades 6 are displaced onto the space a and pushed thumb sufficiently to allow the insertion through passage 3.0f the additional blade I. The

rate of said'bla'd 'is of the same peripheral length as theeieemofetheeblades 4 of the main group,

fbiiintheelugsi extend along of the peripheral length of the foot from the opposite end thereof aspompared with the lugs of blades 4, that is to saw fllonnrthe right.handuend instead.;of from theeleft, ehand'zend: thereof as. shown in-.-.Fig. 3 After insertion, the additionalr-blader'l iswmovedz ontoahe space eh until; it comes intowengagement with itheelastibladee l yonathis. -de-. of:- the inlet passages s. shown: EinF ig'; 51a. ythis-means, the" lugssoft-theradditionabrblade I are -.brought into engagement withrtherlugs.2 of gtheeperipheral disc.- orz ion-e 7 gBetwteenneache wo adiacentzbladesrt .I thenlne seri: ldistance: pieceasB icorrespondihg. in; size": and; shape tOxiZhGcCllt fiWd}! portionszofiltheblade feet; andebetweemblade :1 :andmheradjacent; blade: 6W1. mtroducetaedistanceapiecenilr None ofizsai'didise" facilitatewthe insertiomofrtheidistancemiecedl, their lattemmay b'e tapered..-,or.: pointed like 7a.;Wedge; Therd-istance-epieceszmayybeisealedfinztheir post-xti'ons byi meansizoie rivetsel 0; or by: other 2. approt-i ltiisitozbeinotedcthat theeinventionamay also beapplied: toeblades zami idis aof-r'other profiles than 1 those'ziltustratede in; the: drawingszz. 'An example oft. such ran mDdifi6dfi.p'1O'fi1el-:l$ ShQOWIi in 1 Fig. 9; l-lere-ytheibladezfoot diis provided with endafl'anges I I.2engagingtcinsidetlateralxzfianges I23 formed: on theepenipheraladlsctzportiom By this' means de-'-- flectionrf; of theeprongsi oi 'the: forked blade footmayibezpositiwelytavoidedi What Ihlainr 7 1 a 1. In' a -turbineerot'or of the 'type setforth, a turbine disc; a set of turbine blades -'having--feet" spaced apart-attached te theperiphery of-the turbinedisc by a straddling engagement bet-ween thefeet 0f=ithe- -blades andfithe peri-pheral portion of the 'di'sc, peripherally extending claw sl rapedlugs an d cor're'spondihggrooves formed in ane-abut ting surfaces of said fe'et and saidperipheralportionrrer sealing the blad fetand discin-saiden blades-iofethe smainzgroup :sare :designatedubmthe: fiofigagem-em, said. set oftftupbinesbla' des. .l

numeraLzL-s and arez. provided with. circumferena-l tial-lyeextending outwardly.pointinglclaw=shapel lugs .Seprortidedgifor; instanoe,-.on:a Lofztheapee ripheral lengths ofzthe blade e-feet from. one end;

ini'sei ies-ea main group of blades the feet ofwhich are formed with lugsandgreovesalong-a fraction of their peripheral-length as :reekone'd from one peripherals endr' of the I feet; aminor group of-f' thereofv; Afterzinsertion:ithroughzpassage:3; thee; fifiiiblade ffofngthegfeedi ofgjwh jch blades: 4 arel displaced: to zbothisides i of 2 theeinletz. passage until; at .one :side :of? the ipassage'aitoqthel: v lepftzthereof; Fi 1) asspaceifreeafrom; biades'azre mains; .the peripheral extent aa;-.of .-.whicl:r;isrequal;i to' 236: of r the: peripheraltlength i ofi l a: blade g'fOOiLl while at ithesothergsideiof ,the passage;a'lfreelspacea. is leftithe peripheral lextentsbrlofii-whioh isnequal. to. Ai -30f:theiperipheralJengthmf :arbladeviootfi.. It? is evident; that atheiperipheral length ;o:f ."the:blade gn'eoveefr-eei portions iare cu-t away', a fiiial 1 bla dew haying 'xaefoomofctheasame peripheral- 4 length as the saidzblad'esrof the main groupr'anuzliaving:lugs alldflgIOOXZ-BSEOIEISQLidZffOOt which extendzialong a:-

' 'fractiomofi :the peripheralilengthl th'ereot from the opppsiteiperipherakendcthereof :as;compared with lugseand grooves oiithetbl'ades .of Ethemain roup;: separate ldistaurice gpi'eces inserted-Linethe placeaofil theicutrawampprtionsofuthe feetfof the blades-of:

foot, should bear a--.predeterminedrsrelatiorr tozthew said;Hnmor;gr0up;z andfther-lugsiof the peripheral portion. of the disc being cut away along a peripheral length corresponding to that of the lugs of the blade feet, so as to form an inlet passage for application of one blade at a time to the periphery of the disc.

2; In a turbine rotor according toclaim 1, and in which the distance pieces for replacing the cut away portions of the feet of the blades of the minor group are of the same profile as the cut away portions of the feet of said blades'and of 10 the same peripherallength as said cut away portions.

oscAn ANTON WIBERG.

Images