US2577747A

US2577747A - Method of making turbine blades

Info

Publication number: US2577747A
Application number: US699114A
Authority: US
Inventors: Emil F Gilbian
Original assignee: Thompson Products Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1946-09-25
Filing date: 1946-09-25
Publication date: 1951-12-11
Anticipated expiration: 1968-12-11

Description

Dec. 11, 1951 E. F. GlBlAN 2,577,747

METHOD OF MAKING TURBINE BLADES Filed Sept. 25, 1946 4 Sheets-Sheet l :22; 4 7gymjl/ I INVENTOR. f ym E 5/5/27 Dec; 11, 1951 E. F. GlBlAN 2,577,747

METHOD OF MAKING TURBINE BLADES Filed Sept; 25, 1946 4 Sheets-Sheet 2 7 a Z) "W W O W flfi .ML 1. 0 IM I ff 4d INVENTOR.

[M/L F mam/v Dec. 11, 1951 E. F. GIBIAN 2,577,747

METHOD OF MAKING TURBINE BLADES Filed Sept. 25, 1946 v 4 Sheets-Sheet 3 jig/Z t Q i 7 w I lmlhilll 1 7 [I I I I l l mmvrox. iM L F 695/27 HTTKS'.

Dec. 11, 1951 5-5 GIBIAN 2,577,747

METHOD OF MAKING TURBINE BLADES Filed Sept. 25, 1946 v 4 Sheets-Sheet 4 J JE r I 5 1 z I I 5 1 g /kz. fig/l 17 /7 V INVENTOR.

M/1. F. fine/5w 75 7 Mmm.

elongated cylindrical rod whereas the root-forming portion is in the form of an elongated head on one end of the rod with a major axis perpendicular to the axis of the blade portion and extending on each side thereof at one end of the bladeportion, the root-forming portion being thicker in the side views than the blade-forming portion to allow for the additional thickness necessary at the root portion of the final blade.

The die and punch members from which the blank of Figures 1 and 2 is converted to a final forged blank, are shown in Figures 3 and 4 respectively. In the case of the die member of Figure 3. it will be observed that a flat recess portion 22 is provided to act upon and receive the blade portion 2| of the rough blank. This'portion contains a suitable dimple recess 23 for forming a localized reference button in the blade portion of the final forged blank, this button being located along the axis of the final blade. In addition, a recess 24for a boss is provided. The purpose of the button formed from recess 23 and the boss formed from recess 24 will be described in further detail hereafter.

In addition to the blade receiving portion of die 22, a root portion shown generally at 25 is provided. This portion consists of an elongated narrow recessextendin at a slight angle relative to the axis of the blade portion of the die 22. The purpose of this angle is to give the top of the final blade the slight taper ordinarily desirable in blade mountings for gas turbines and the like. At the center of the root portion 25 a dimple recess 26 is provided for a root button, this recess being located on the axis of the blade portion 22 of the die and at a point thereon having a predetermined relation to the root portion. Viewed differently, this recess is located on the blade axis at a fixed distance relative to the airfoil sections of the finished blade.

The punch of Figure 4 is shaped to coact with the die of Figure 3 so as to shape the opposite surface of the final forging. This member has a flatblade forming protuberance 21 acting upon the portion 2| of the blank to flatten it into the recess 22 of the die while imparting an airfoil sectional shape thereto with a slight helical twist or pitch. The punch portion 21 is free from dimple recesses but does have a boss forming recess 28 aligned with die recess 24. Recess 28 unlike the recess in the die member is provided with lateral extensions. These extensions provide dam-like recesses which stop free flow of metal out of the ends of the die members.

The root portion of the punch, designated generally at 29, is identical with the root portion figure that the root portion of the blade, desig- 'nated as" 30, has symmetrical top punch formed and bottom die formed halves except that button 3| is produced on the bottom .die formed half. Similarly, button 32 of the blade portion 41 extends only on the same side as button 3|. Re-

,cesses 24 and 28 in the die and punch members provide a symmetrical boss 33 on the forging.

Figure 6 shows a view of the finished forging taken from bottom and showing the location of buttons 3| and 32.

Figure 7 shows a similar view of the top of the blade except that the extending portion 34 has been removed.

An important feature of this invention resides in providing buttons 3| and 32 on the root and blade portions of the final forging respectively. It will be observed that these buttons located the axis through the center of the blade forging. However, these buttons need not be located in the forging member with an excessively high degree of accuracy inasmuch as a certain amount of excess material-may economically be allowed for the forging processes and it is only necessary to locate the buttons so as at all times to prevent machining the blade in a manner to exceed these allowances. Thus, while these buttons act as guides they need not be guides of extreme accuracy and can readily be made by the forging process. In one method of applying this invention, for example, these buttons are approximately one-eighth inch in diameter and extend upwardly from the root and blade surfaces approximately the same distance. It should be observed that punch and die wear tends to be uniform on all sides of the buttons. Thus, when these but tons are inserted into V-notches provided for the purpose, the blade forging is accurately positioned despite the fact that there may be slight imperfections in the exact surface of the buttons themselves. This feature will be evident from the following discussion illustrating the process 'used in manufacturing a typical turbine blade from the final forging.

The first operation in the machining process is to trim the ends of root portion 30 relative to the axis through buttons 3| and 32. A plan view of a jig useful for this purpose is shown in Figure 8. This jig has mounting holes 35 provided for attachment to a suitable table and two upwardly extending portions, shown generally at 38 and 31, respectively. Portion 36 includes member 38 which has a fiat upper surface and a recess 39 located therein. This recess is of V-notch construction to cooperate with the button 3| located on the root portion of the finished forging. Portion 3! has slot 49 located in the upper surface thereof and extending along an axis passing through recess 39. This slot is of V-shape to cooperate with button 32 on the blade portion of the finished forging.

A cross-sectional view of the jig of Figure 8 with the forging located thereon is shown in Figure 9. From this figure it is evident that the forging is positioned along the axis between the buttons 3| and 32 by button 3| which is located on the root portion of the blade whereas button 32 on the blade portion prevents rotation about this point and establishes the central axis through the blade. Thus, the ends of the root portion 30 of the finished forging may be ground with respect to the fixture inasmuch as buttons 3| and 32 accurately position the forging with respect thereto. The resultant blade may be checked with a gauge such as shown in Figure 10. In this gauge a slot 4| is provided in which but tons 3| and 32 may slide, this slot being-of a V-notch construction. Gauge members 42 are located on each side of slot 4| and are separated therefrom by the amount of the desired blade length. Thus, by sliding the ground blade blank through this gauge the degree of accuracy of machining thereof may readily be evaluated, the blade refusing to passif the length of the root portion is excessive on either side of the axis through buttons 3| and 32 and an air space showformed by buttons" 3| and 32. My

' and adequate material will'fbe available root portion is milled along an axis rela spare turbine blade shown in cross-sectio' iniFigiire 'rately to 11. ,It is the purpose or this jig" a place a hole in the end or boss as of thebiade forging. To this end,,a' recess-n-i's-provided, this recess being shaped so .as to cans nttoii "31 on the root portion of the blade to-cooperate with a fixed V-shaped-notch, thereby positionin the root portion of the blade onthe'fixtuf Acrosssection View of this engagement is-shown in Figure ll'b. Similarly, member ;44 against-which button 32 is pressed has .a vertically extending V-Shaped notch which appears presentation as shown in Figure 11a. This positions the button32 with respect to the d'rilljig so as to prevent rotation of the'blade' about button" 31, Inasmuch as both

buttons

31 and 32 are positionedrelati've to'th'e axis of drill by reason of the abovedescribed notches, the hole placed in" theboss 33 isalso accurately positioned with respect thereto so that this hole maysubsequently' used in the machining processes. A swingably mounted member 46 is provided to hold the blade for in 41 against member 44' and i s provided with re sfilient meanssucl'ras-spring 48 '(sliowr'i'iii dashed lines) to swing itawayrromti 'tdrgi g when released. Member Ml and bolt 50 maybe used tolock member 46in place for'the drilling process. ,1

At the conclusion of the drilling operation illustrated in Figure '11,'the blade forging has four points of reference. "Two of these points are

buttons

31 and 32 which define the through the blade portion of thegfinalbl'ade and the positions of the various airfoil sectionsalong the blade. Secondly, the ends of the root p rtion have been machinedto anequai length elative to the button 3| and the ax through buttons 3i and .32. been provided "hosis'i33 whlchis bination' of these references maybe used" in the further machining operations. 1 V

In Figure .12. the forging is shown positioned in a lathe for grinding the leading and trailing edges of the airfoil section. As shown in the figure, the forging is supported by the headstock of the mineengaging theen s" ,ofI-root portion 311 which have been previously and accurately located relative to-the axis" through the final blade by means of above-described .op,e1:ations. The mounting hole in the boss 33 provided by the above described' drilling operationis :used to support the opposite end of the blade-the tail-piece of the lathe. Thus, the forging eurately rotated about the blade axis and ing operations may be conducted with assu rice that the finals'ur'face's will'becqrrectly nos sides. V v the ,final stages of blade manufaotu the fi'nal blade axis corresponding to the :iinal position desired of the blade. maybe accomplished, for example, by'positioning the blade in a-milling machine by'-'the-;hole in bosses-and theend's of the root portion- 'iiraimanner sfimilar hithatofxl 'igure .12. .Tliefiblade isithus accurately located in the milling machine and. cutter op- 6 eratlons may be conducted with assurance, thus producing a final milled blade of the shape shown in igureia In Figure 14 the final breaching operation has been completed. In this case button 3| on the root portion 30 of the blade has been removed and this portion of the blade cut down to provide extension '52 which is used to bottom the blade in a groove ofa compressor wheel for a jetpropulsion engine (not shown).

A later step in the blade-production process is cutting the end of the blade portion 41 rela tive to the surface of the root portion. At this time the button 32 on the blade portion is removed and a blade such as shown in Figure 1 5 is provided. The ends of the root portion are then beveled to provide the final blade shown Figures 16 and 17, Figure 17 being a top view of the final structure.

It will be apparent to those skilled in the-art that, while I have shown buttons 3| and i2 positioned along the blade axis of the forging, they may be placed at any points on the blade having known relation to the airfoil sections and axes of the finished blade. Thus, for example. one button can be placed on the intersection of the root portion and blade portion and the other located on the root portion, thereby enabling the blade axis to be positioned by the known relation between the axis through the root portion and the axis through the blade portion and the airfoil sections to be located by reference to the axisthrough the root portion. 7

It will be apparent to those skilled in the art,

that I have provided an improved method of manufacturing turbine blades which does not require forgings with accurately located surfaces or an excessive allowance for error in "lo eatin the axis through the forgings. The but tons- 31 and 32 provide a sourceof reference posi' tion independent of the dimensional errors that are inherent in the edges of the forgings and thereby provide a basic source of reference for turther' operations. If, for example, the blade forgings are produced in one locationby one manufacturer and are sold in commerce to'be used by other manufacturers in making a variety of blade configurations having diiierent airfoil surfaces, angles of tilt, -etc., the first manufacturer may place .the' buttons in the blade forgment with theaxis of the blade portion" to inan--in-..aplane passing through the axisof the blade portion and substantially normal to the plane of the blade blank. Similarlyby thexterm in alignment with the axis of the root portion I mean- 'located ina plane passing through the axis of the root portion and substantially .pers pendicular tc-the planeof the blade blank.-

"While I have shown and described-a ipartic'us lauarrangement of my invention, it will of coursebe understood that I do not wish to be limited thereto since many modifications both "in the structures disclosed and the arrangement of the processes may be made without departing from thez-spiritand scope-thereof. I, of c0ur'se', con:- t'e'mplate by the appended .claims to cover any Such modifications .as fall-within the true-spirit i5 scope'of my" invention.

amt 41 I claim as my invention:

n 1. In a method of making turbine buckets, the improvements which comprise die-forging a metal blank having an anchoring root at one end, an extending portion at the other end, and an air foil portion between said ends, said anchoring root being in angular relation to the air foil portion and said extending portion projecting longitudinally beyond the air foil portion, simultaneously with said die-forging that produces said blank with said root, said extending portion, and said air foil portion forging on one face of the blank a first button on the root portion and a second button on the extending portion beyond the air foil portion, said buttons lying on a selected center line of the blank, engaging the buttons in recesses to hold the blank against lateral and longitudinal shifting, machining opposed surfaces of the root portion of the thus held blank whereby said surfaces will be gauged from the buttons, anchoring said opposed machined surfaces in a fixture to secure the blank, removing the first button from the root while machining the root of the thus secured blank to finished dimensions whereby the finished root surface will be gauged from said opposed surfaces and will be finished in accurate relation to the air foil portion, and cutting the extending portion and button thereon from the air foil portion to produce a turbine blade having an anchoring root and an air foil portion projecting therefrom.

2. The method of manufacturing by forging and finishing operations turbine blades and the like articles consisting of air foil portions and anchoring roots located in exact angular relation and position relative to the air foil portions, the improvements which comprise forming by dieforging a blank having an intermediate air foil portion, a root portion at one endthereof in angular relation to the air foil portion and a longitudinally extending portion at the other end thereof, simultaneously with said die forging to produce said blank having said air foil portion, said root portion, and said extending portion forging on one side of the blank first and second locating buttons in spaced relation and lying on a selected center line of the air foil portion, said first button being located on the root portion in longitudinally spaced relation to the air foil portion and said second button being located on the extending portion in longitudinally spaced relation to the air foil portion, engaging the buttons in anchoring recesses including a first recess for the first button which surrounds the button to hold it against lateral and longitudinal movement and a longitudinally elongated V-shaped slot for the second button holding the second button against lateral displacement to coact with the first recess in aligning the blank along the center line of the air foil portion, machining the thus anchored blank, gauging the'machined portions of the blank from the thus anchored buttons, machining the root portion to finished dimensions, removing the first button in machining the root portion to finished dimensions, and cutting off the extending portion from the end of the air foil section thereby removing the second button without machining or grinding the air foil portion.

3. The method of making turbine blades which 9 comprises forming a starting blank with a thickened'portion at one end and an elongated shank portion extending therefrom, die-forging said blank to form a blade blank with a root portion composed of metal from the thickened portion of the blank, an air foil portion composed of metal from the shank portion of the blank, and an undeformed end portion beyond the blade portion, simultaneously with the formation of said blade blank forming a fixed button on the root portion and a second button spaced materiallyfrom the first button on the portion of the blank beyond the blade portion and aligned with th elongitudinal axis of the blade on the same side of the blank as the first button, seating the buttons in recesses coacting with the buttons to hold the blade blank against lateral and longitudinal shifting, machining the thus held blade blank, gauging the machined portions from the thus held blade blank, cutting off the end portion of the blade blank beyond the specified blade length thereby removing the second button, and machining the root to finished dimensions thereby removing the first button.

4. The method of making turbine blades which comprises forming a starting blank with a thickened portion at one end thereof and an e1ongated shank portion extending therefrom, dieforging said blank to form a blade blank with a root portion composed of metal from the thickened portion of the blank, an air foil portion composed of metal from the shank portion of the blank, and an undeformed end portion beyond the blade portion composed of shank metal beyond the blade portion, said root portion having its longitudinal axis at an angle to the longitudinal axis of, the blade portion, simultaneously with the formation of the blade blank forging a pair of upstanding buttonsat opposite longitudinal end portions of the blade blank and in materially spaced relation from each other on one face of the blank, said buttons coacting to define a longitudinal axis through the center of the blade blank and one of said buttons on said blade axis having an abutment surface adapted to hold the blade in fixed longitudinal position, seating the buttons in recesses coacting with the buttons to hold the blade blank against lateral and longitudinal shifting, trimming the thus held blade blank to remove excess metal, successively machining and broaching the trimmed blade blank to fixed dimensions gauged from said buttons, and cutting off the undeformed shank end portion of the blade blank.

EMIL F. GIBIAN.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS Number Name Date 1,345,859 Kerr July 6, 1920 1,359,227 Brolinson Nov. 16, 1920 1,373,919 Steenstrup Apr. 5, 1921 1,680,327 Eicher Aug. 14, 1928 2,125,881 Berliner Aug. 9, 1938 2,192,008 Gehret Feb. 27, 1940 2,221,684 Smith, Nov. 12, 1940 2,274,667 Colwell Mar. 3, 1942 2,299,975 Groene Oct. 27, 1942 2,302,229 Lampton Nov. 17, 1942 2,333,859 Groene Nov. 9, 1943 2,373,827 Halford Apr. 17, 1945 FOREIGN PATENTS Number Country Date 1 115,869 Great Britain May 21, 1918 Germany Dec. 20, 1919