US2279258A

US2279258A - Turbine blading

Info

Publication number: US2279258A
Application number: US272414A
Authority: US
Inventors: Robert C Allen; Wilson James
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1939-05-08
Filing date: 1939-05-08
Publication date: 1942-04-07
Anticipated expiration: 1959-04-07

Description

7, R c ALLEN E AL TURBINE BLADING Filed May 8, 1939 2 Sheets-Sheet l E If v April 7, 1942.

R. c. ALLEN ET AL TURBINE BLADING Filed May 8, 1939 2 Sheets-Sheet 2 II u m Patented Apr. 7, 1942 TURBINE BLADING Robert 0. Allen, Wauwatosa, and James Wilson, West Allis, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a

corporation of Delaware Application May 8 1939, Serial No. 272,414

12 Claims.

defining surfaces disposed in nested or in par tially nested relationship. The driving fluid is applied intermittently by means of circumferentially spaced nozzles or groups of nozzles and the driving fluid subjects the blades to forces that may amount to many hundreds of pounds per blade. Consequently, when blades of great ,relative width are employed under conditions of high rotative speed and high temperature and pressure, the use of circumferential retaining grooves becomes impractical because of the great axial width of the retaining rims at the sides of the grooves and also because of the great dimculty of providing a suitable closing or locking device for holding the last blade in place.

The usual practice is to enlarge the circumferential retaining groove at one or more points to permit the insertion and removal of the blades and the last'blade or blades to be inserted are secured in position by means of suitable wedging and locking members. Enlarging the circumferential retaining groove materially weakens the rim portions of the groove in the region of the enlargement and the high bending moments set up by the intermittent application of thedriving fluid renders the obtainment of a stable structure highly impractical. In fact,

there is no known manner of inserting and se-\ curing the last blade in a circumferential blade retaining groove which is practical and which will permit the use of highly emcient passages under conditions of maximum capacity and maximum temperature.

It is therefore an object of this invention to provide a novel blade assembly wherein each blade of a circumferential blade row in which the spaced concave convex passage defining surfaces on adjacent blades are disposed in nested or in partially nested relationship, is secured to the turbine spindle in exactly the same manner.

Another object of this invention is to provide a novel blade assembly wherein the blades coacting to form a c rcumferential blade row, in

which the spaced concave convex passage de- Q fining surfaces on adjacent blades are disposed in nested or in partially nested relationship, are mounted in a circumferential row of spaced axially extending grooves.

Still another object of this invention is to providea novel blade retaining grooving arrangement for turbine spindles.

A further object of this invention is to provide a novel method of inserting blades in a turbine spindle to form a circumferential blade row in which the spaced concave convex passage defining surfaces on adjacent blades are disposed in nested or in partially nested relationship.

The invention accordingly consists of the method of blade insertion and of features of construction, combinations of elements, and 'arrangement of parts as more fully pointed out in the appended claims and in the detailed description in which:

Fig. l is a partial sectional view of the turbine embodying the invention;

Fig. 2,is a sectional view of a portion of the turbine spindle taken on line 11-11 of Fi 1;

Fig. 3 is a view taken on line IIIIII of Fig. 1 with a portion of the shrouding broken away to show the cross-sectional configuration of the blades and fluid passages;

Fig. 4 is a bottom plan view of'the blades for a circumferential blade row disposed in cooperative relationship about a circular form;

Fig. 5 is a plan view of a form having grooves conforming with the axial grooves in the turbine spindle;

Fig. 6 shows the blades assembled in their proper cooperative relationship with respect to the forms shown in Figs. 4 and 5, the forms being shown in section;

Fig. '7 is a vertical section through a portion of the turbine spindle and a hydraulic press' for simultaneously inserting a circumferential row of blades in their respective spindle grooves;

Fig. 8 is a plan view of a form used for come pleting the insertion of the blades in the spindle grooves: and

Fig. 9 is a central vertical sectional view of the form shown in Fig. 8. The turbine, reference being had to Fig. 1, comprises a spindle i having two circumferentially extending rows of

blades

2 and 3, which rows are axially spaced apart to cooperatively receive therebetween a row of stationary blades & secured to the casing 6 in a conventional manner. The blades are prevented from moving in a lateral direction with respect to the circumferential blade rows by means of spacing blocks 1 and the conventional locking groove and ring arrangements 8. The casing 6 is provided with for an understanding of the invention; have been omitted to simplify the disclosure. The

blades

2 and 3 forming the circumferential blade row's 2 each have, as best shown in ms." 2 and a, a 'root portion il, a'body portion II, a passage defining portion l2 presenting opposed concave convex passage defining surfaces i4 and i6, respectively. andan integral shroud portion II. The concave surface N on one blade coacts with the convex surface I of the next adjacent blade to formtherebetween -a pe ll for the driving fiuid. The blades 2 define the passage II by having the coacting concave convex surfaces on adjacent blades disposed in partially nested relationship whereas the corresponding passage defining surfaces of the blades 3 are not disposed in partially nested relationship. Due to this difference in construction, the abutting side surfaces of the shrouds l1 and of the body portions I2 01' the blades 3 are plane surfaces whereas the corresponding surfaces of the blades 2 are curved.

The blade pitch is essentially the same in both of the circumferential blade rows and whether the coacting concave convex passage defining surfaces on adjacent blades are disposed in partially nested relationship is determined by the inlet and outlet angles of the blades and by the widthof the fluid passage. v

As shown in Fig. 3,the dividing line between adjacent blades as defined by the curved abutting side surfaces 'of the shrouds II and the.

body portions l2 of the blades 2 does not coincide with concave fluid driving surfaces I 4. This ar- -rangement provides a fiuid confining passage which is sealed at the outer and inner boundaries defined by the coacting concave convex surfaces l4 and I6, respectively. The fiuid pressure within the passage is greatest at the outer and-inner boundaries and with this construction, it is not fecting centrifugal stability as the center or! a gravity and the line of action-of the .centrifugal force is thereby displaced in a direction such that the desired centrifugal moment may be obtained with a blade having less mass.

The spindle I, reference beinghad to .Figs. 1 through 3, has a circumferential groove ll approximately equal in width to the distance the blade roots are spaced apart to form the axially spaced circumferential blade rows and a circumferential row of spaced axially extending blade retaining grooves 2| of greater depth than the circumferential groove I2. The axial grooves 2| extendlaterally beyond the sides of the circumferential groove is distances approximately equal to the axial length of the root portions ll of the

blades

2 and 3.

the root portions ii of the

blades

2 and 3 and of the spacing block I are slotted as shown in Fig. 2 to provide mutually coasting retaining surfaces 22. The relative depth of the grooves I! and 2| should be such that the portion of the walls of the grooves 2| which lie below the bottom surface of the groove I! present retaining surfaces effective to. secure the spacing block I against movement in a radial direction.

The best procedure to follow in order to obtain the previously described arrangement of grooves is to first cut the circumferential groove I, the cross-sectional configuration of which is preferably rectangular and then to cut the axial retaining grooves 2|. This procedure enables ea h of the axial retaining grooves all to be made with a single breaching operation thereby materiali reducing the time required and-the .machining 4 costs. The concave convex passage defining surfaces II and I! and the root portion. of each of the

blades

2 and 8 are accurately machined and finished.as is also the same one side surface of each blade as defined by the side surfaces of the body and shroud portions l2 and I1 respectively whichare adapted to abut the body and shroud portions of the next adjacent blade. The opposite side of each blade is machined to the approximate dimension desired there being excess material left on this side which is removed whenthe blades are fitted.

Each blade after being machined as previof the distance between a surface of the measur- I ing device and the accurately machined side of the blade. This measurement accurately determines the material to be machined from the unfinished side of the blade which is to be inserted in the groove containing the measuring device. The blade and the groove in which the blade was partially inserted are marked for future identification and this blade and the measuring device are then removed. A blade is then selected for insertioninthe groove from which the measuring device was removed and is marked for further machining as indicated by the measurement previously taken. This blade'and the measuring been measuredand identified with respect to the The walls 'of the axial grooves 2| and the corresponding side walls of grooves in which the blades are to be inserted in their proper cooperative relationship. The unfinished sides of the blades are then machine finished as indicated by the measurements.

The blades for the first circumferential bladerow in which the fiuid passages it are defined by having the coacting cocave convex surfaces on adjacent blades disposed in partially nested relationshipas represented by the blades 2 in Fig. 3 must now be inserted in their respective grooves in pairs to determine whether further hand fitting is necessary. A pair of blades previously fitted with respect to one another as above described are held together in proper cooperative relationship and an attempt is made to simultaneously insert the blades in their respective grooves. The proper grooves can be readily idenseparately inserted and fitted in the usual manferential blade row have been finally fitted, the.

diameter of the spindle I measured at the bottom of the axial grooves 2| and the blades may be arranged in their proper cooperative relationship with their roots contacting the form 24 as shown in Figs. 4 and 6 by moving the individual blades in a radial direction with respect to the form 24. Any suitable means such as the flexible band 26 may be placed about the blades as shown in Figs. 4 and 6 and tightened to hold the blades in position against the form 24. It should be understood that the arrangement of the blades about the form 24 as previously described is effected on a table or other suitable supporting surface 21 (Fig. 6). The form 24 has an annular, coaxially extending guide member 28 and the thickness of the form 24 is preferably considerably less than the axial length of the blade roots H as shown in Fig. 6.

The outer periphery of the annular form 29- shown in Fig. has slotted blade retaining spaced bolt holes 44 equal in number and arranged for alinement with the threaded holes 32 in form 29. The side wall of the'cylindrical.

member 4| is provided with openings 43 for inserting cap screws into the holes 44 in the face plate 43 which enables the form 29 to be rigidly secured to the annular face plate 43 of the cylindrical member 4| by means of cap screws 41 as shown in Fig. 7. Fluid for operating the press is admitted and drained from opposite sides of the piston .31 as desired by means of the pipes and

ports

48 and 49, respectively.

The form 29 with blades 2 mounted thereon 'aspreviously described is attached to the face plate 43 .by means of the cap screws 41. The spindle is supported in any suitable manner 'such as by means of a crane (not shown) and the spindle and press are brought into the cooperat-ive relationship shown in-Fig. '7 with the end.

of the spindle shaft extending within the hollow cylindrical member 4| in coaxial alinement with the cylinder 36 of the press 33 so that the cylindrical member 4| may be reciprocated in coaxial alinement with respect to the spindle and grooves 3| which are identical in cross-sectional configuration, arrangement and number to the axial grooves 2i in the spindle The form 29 also has a plurality of circumferentially spaced threaded holes 32 located on a circle concentric with respect to the center of the form. The inside diameter of the form 29 is greater than the diameter of the spindle shaft as shown inFig. '7 and substantially equal to the outside diameter of the annular guide member 28 on the form 24. The guide member 28 serves to center the form 29 with respect to the form 24 as shown in Fig. 6. After the blades have been arranged about the form 24 and secured thereto as described in the preceding paragraph, the form 29 is placed upon the form 24 to effect the relationship shown in Fig. 6 with that portion of the roots of the blade which extend above the form 24 disposed in the grooves 3| of the form 29. The roots of the blades fit the grooves 3| in the form 29 with suflicient snugness so that when the retaining band 7 26 is loosened, the form 29 and the blades 2 may one another and all'that remains to be done isto so position the form 29 with respect to the spindle I that the roots of the blades are in axial alinement with the corresponding grooves 2| and' to' simultaneously insert the roots of the blades in their respective grooves. Apparatus suitable for simultaneously pressing the blades into their respective grooves is shown in Fig. '7 and comprises a hydraulic press 33 having a base 34, a cylinder 36 containing an actuating piston 31 and a guide portion 38, a press plate 39 formed integral with the guide portion 38, and a hollow cylindrical member 4| of welded construction which is removably secured to the press plate 39 by means of bolts 42. The end of the cylindrical member 4| opposite the end secured to the press plate 39 consists of an annular face plate 43 having an inside diameter greater than that of the spindle shaft and circumferentially the axial grooves 2|. The roots H of the blades 2 may then be readily brought into axial alinement with their respective grooves in the spindle by rotating either the spindle i or the cylindrical member 4| with respect to the press face plate 39. In the arrangement shown, the blade roots II and the grooves 2| are brought into proper alinement by slowly rotating the spindle i, which is held against axial movement in a direction away from the press by a fixed means 5|, in any desired manner. When the blade roots II and the grooves 2| are properly alined, the press 33 is operated to move the form 29 towards the spindle and the blades are simulta neously pressed into their respective grooves until the form 29 abuts the side of the spindle I. The cap screws 41 which secure the form 29 to the face plate 43 are thenremoved and if the flexible retaining-band 26 has not already been removed, it is removed at this time. The press is then operated to move the face plate 43 away from the spindle I which leaves the form 29 suspended on the spindle I by means'of the blades 2.

Fi s. 8 and 9 show an annular form 52 which is adapted to be secured to the face plate 43 in order to. completely insert the blade roots into the grooves 2|. One side of th s form is provided adjacent its outer periphery with a circular row are preferably defined by radial planes and their circ mferential width is such that when the projections 53 are moved axially into the grooves 2|. the plane side'surfaces of the projections will cooperate with the walls of the grooves and prevent th projecti ns from bending. The radial len th f the projections 53 should approximately efllial the radial depth of the grooves 2|, but in n event should the diameter of the circle defi ed by the inner ends of these projections be into the grooves 2|. Form 52 is provided with threadedbolesllarrangedtoalinewiththeholes proper position within the grooves II. The press V is then operated to-withdraw the face plate 43 from the vicinity of the spindle, the forms fl and I! are removed, and the locking arrangement 8 applied to secure the blades against lateral movement with respect to the circumferential blade row. If the blades 8 and the spacing blocks I were inserted before the blades 2 nothing further remains to be done, but it may be desirable to insert the spacing blocks I and the blades 3 after the blades 1 have been inserted. This may be done with the arrangement shown as the spacing blocks I and the blades I can be separately inserted at the opposite end of the grooves 2|. Obviously, if the operating pressures, temperatures. etc. dictate theme of blades in the second circumferential blade row having coacting concave convex passage defining surfaces disposed in partially nested relationship, these bladesowould be simultaneously inserted in the manner described with respect to the blades 2. In this event, the blades forming the secondcircumferential blade row would be inserted first. I I

The use of a hydraulic press or any other suitable type of machine for forcing the blades into thegroovesisnotessentialasthebladesmaybe manually inserted by using the types of forms disclosed or anyother suitable means on which the blades can be arranged in their proper co-' operative relationship, retained in this position. and the roots simultaneously inserted in their respective grooves. In this connection, it should be obvious that the cross-sectional configuration of the blade roots and of the retaining grooves may be varied as desired. The invention is ob.-

viously applicable to all types of turbines in which one. or more circumferential blade rows are formed byblades having coacting concave convex passage defining surfaces disposed in 'a circumferential row of spaced axially extending side entry retaining grooves, the cross-sectional configuration of which conforms with that of the blade roots, with the opposed passage defining surfaces on adjacent blades disposed in nested or in partially nested relationship which comprises fitting the blades to obtain the necessary cooperative relationship between coactingsur-' faces on adjacent blades, placing the blades'together in their proper cooperative relationship and securing the blades in this position, moving the blades thus secured together into a position such that the root portion of each blade isin ously inserting the roots of the individual blades into the axial retaining grooves.

2. The method of 'assemblingturbine blades in a circumferential row of spaced axially extending side entry retaining grooves, the cross-sectional configuration of which conforms with that of the blade roots. with the opposed passage defining surfaces on adjacent blades disposed in nested orin partially nested relationship which comprises tion of each blade is in substantial axial alinement with a groove in the circumferential groove row, and simultaneously inserting the roots of the individual blades into'theaxial retaining grooves.

-3. The method of assembling turbine'blades in a circumferential row of spaced axially extending side entry retaining grooves, the crossship which comprises simultaneously inserting a substantial axial alineinent with a groove in pair of adjacent blades into adjacent grooves in the circumferential row, fitting the blades to obtain the necessary cooperative relationship between coacting surfaces and then removing the blades from the grooves,repeating this operationusingpairs ofblade'sconsistingofoneblade of the pair previously fitted and the next adjacent blade until all blades have been inserted' in their respective grooves and fitted with respect-to adjacent blades, placing the bladea'together in their proper cooperative relationship and securing the blades in this position. moving the blades thus secured together into a position such that the root portion of each blade is in substantial axial alinement with the corresponding groove in the circumferential groove row, and

simultaneously inserting the roots of the individual blades into the corresponding axial retaining grooves. I

4. A moving blade assembly for elastic fluid turbines comprising a spindle having a circumferential row of spaced axially extending and substantially straight side entry blade retaining grooves, a blade secured in each groove, said blades each including a convex and a concave fluid directing side surface, and said grooves and blades being so constructed and arranged that the convex side surface on each blade is disposed in partially nested passage defining relation with respect to the concave side surface on the next adjacent blade.

5. A moving blade assembly for elastic fluid turbines comprising a spindle having a circum ferential row of spaced axially extending and substantially straight side entry blade retaining grooves each of which is of suilcient length to retain two blades in axially'spaced relation such that the blades in the circumferential row of axially extending grooves coact andform axially spaced circumferential blade rows adapted to receive therebetween a circumferential row of stationary blades, two blades secured in each groove in axially spaced blade row forming relation,

said blades each including a convex and a concave fluid directing side surface, and said grooves and blades being so constructed and arranged that the convex side surface of each blade in one circumferential blade row is disposed in partially nested passage defining relation with respect to the concave side surface on the next adjacent blade in said-one row.

' 6.' A moving blade assembly for turbines in which circumferential blade rows are axially spaced to receive therebetween a circumferential row of stationary blades comprising a spindle having a circumferential groove approximately equal in width to the distance the blade roots are to be spaced apart to form the axially spaced blade rows, a circumferential row of spaced axially extending side entry retaining grooves each of which is of greater depth than said circumferential groove and extends laterally beyond the sides thereof thereby providing axially spaced blade root retaining portions, two blades in each axial groove having their root portions secured in said spaced blade root retaining portions and forming axially spaced circumferential blade rows, and means including a spacing block disposed in that portion of each axial groove which is below and merges with the bottom portion of said circumferential groove operable to prevent movement of the blades longitudinally of the axial retaining grooves.

7. A moving blade assembly providing axially spaced, circumferential blade rows adapted to cooperatively receive therebetween a circumfere ential row of stationary blades comprising a spindle having a circumferential groove approximately equal in width to the axial distance the blade roots are to be spaced apart to form the axially spaced blade rows, a circumferential row of spaced axially extending side entry retaining grooves each of which is of greater depth than said circumferential groove and extends laterally beyond the sides thereof, a spacing block disposed in that portion of each axial groove which v is below and merges with the bottom portion of row of spaced axially extending side entry retaining grooves each of which is of greater depth prising a circumferential groove approximately equal in width to the distance the blade roots are to be spaced apart to form the axially spaced blade rows, and a circumferential row of spaced axially extending side entry retaining grooves each of' which is of greater depth than said circumferential groove and extends laterally beyond the sides thereof distances approximately equal to the axial length of the=root portions of the blades adapted to be "secured therein thereby providing axially spaced blade root retaining portions and an intermediate spacing block retaining portion.

10. A turbine spindle having means for re-' taining blades in circumferential rows axially spaced apart to cooperatively receive therebetween a circumferential row of stationary blades comprising a circumferential groove approximately equal in width to the distance the blade roots are to be spaced apart to form the axially spaced blade rows, and a circumferential row of spaced axial side entry retaining grooves each of which is of greater depth than said circumferential groove and extends laterally beyond the sides thereof distances, approximately equal to the axial length of the root portions of the blades adapted to be secured therein, said axial grooves each having their side surfaces including the portions which are below and merge with the bottom of the circumferential groove slotted to provide retaining surfaces. 7

11. A turbine spindle having means for retaining blades with root portions presenting opposed multiple slotted retaining surfaces in circumferential rows axially spaced apart to cooperatively receive therebetween a circumferential row of stationary blades comprising a circumferential groove approximately equal in width to the distance the blade roots are to be spaced apart to form the axially spaced blade rows and of a depth less than that of the blade roots by at least the width of a retaining slot, and a circumferential row of spaced axially extending side entry retaining grooves each of which has a cross-sectional configuration conforming with that of the blade roots and each of which extends laterally beyond the sides of said circumferential groove distances approximately equal to the length of the root portions of the blades to be secured therein.

12. A turbine spindle having means for retaining blades with root portions presenting opposed multiple slotted retaining surfaces in circumferential rows axially spaced apart to cooperatively receive therebetween a circumferential row, of stationary blades comprising a circumferential groove approximately equal in width to the distance the blade roots are to be spaced apart to form the axially spaced blade rows and of a depth less than that of the blade roots by at least the width of a retaining slot, and a circumferential row of spaced axially extending side entry retaining grooves each of which has a depth conforming with that of the blade roots and each of which extends laterally beyond the sides of said circumferential groove distances approximately equal to the axial length of the root portions of the blades to be secured therein, said axial grooves including the portion below the bottom of the circumferential groove having slotted retaining surfaces adapted to coact with the slotted retaining surfaces of the blade roots.

. ROBERT C. AILEN.

JAMES WILSON.