US 3745628 A
A rotor structure having at least two radially extending rotor disks. The disks are adjacent to each other and have a knurled portion disposed on one of the disks. The disks are compressed, thereby embossing the knurled portion onto at least one of the disks to prevent relative rotational movement of the disks. Bolts are axially disposed through the disks to prevent axial movement of the disks.
Description (OCR text may contain errors)
United States Patent 1 Stahl [4 1 July 17,1973
1 1 ROTOR STRUCTURE AND METHOD OF CONSTRUCTION  Inventor: William F. Stahl, Media, Pa.
 Assignee: Westinghouse Electric Corporation,
 Filed: July 29, 1971  Appl. No.: 167,141
 US. Cl. 29/156.8 R, 29/432, 29/445,
416/198  Int. Cl 823p 15/04  Field of Search 416/198 A, 244 A,
 References Cited UNITED STATES PATENTS 3,472,534 10/1969 Stevens 151/37 3,452,843 7/1969 Smith 29/156.8 R 3,078,899 2/1963 MacLean et al.... 151/37 2,741,454 4/1956 Eppley 416/198 A 2,303,032 11/1942 Dusevoir 287/113 1,348,667 8/1920 Snyder 29/432 1,017,820 2/1912 Svebilius.... 416/200 2,427,614 9/1947 Meier 416/201 2,452,782 ll/1948 McLeod et al. 416/201 2,650,017 8/1953 Pedersen et a1. 416/201 X 2,743,080 4/1956 Feilden 416/198 FOREIGN PATENTS OR APPLICATIONS 864,440 4/1961 Great Britain 416/198 A 785,002 10/1957 Great Britain 416/198 A Primary Examiner Charles W. Lanham Assistant Examinr-D. C. Crane Attorney-A. T. Stratton et al.
 ABSTRACT A rotor structure having at least two radially extending rotor disks. The disks are adjacent to each other and have a knurled portion disposed on one of the disksv The disks are compressed, thereby embossing the knurled portion onto at least one of the disks to prevent relative rotational movement of the disks. Bolts are axially disposed through the disks to prevent axial movement of the disks.
3 Claims, 5 Drawing Figures 1. ROTOR STRUCTUREA'ND METHODOF CONSTRUCTION BACKGROUND OF THE INVENTION In a gas turbine power plant, the rotor structure is comprised of compressor and turbine portions, each portion including a plurality of disks. The disks are ative to each otherand to transmit torque. The'disks are held in an assembledrrelationby a plurality of 'stay rods which are longitudinally disposedthrough'bores in the disks. This type of rotor constructionis commonly known as a curvic clutch and is shown inH; O; Pederson et al. U.S. Pat; No. 2,650,017 issued'Aug. 25, 1953.-
and assigned to the same assignee as the present invention.
While curvic clutch disks adequately. transmit"v high torque, the devices which machine the teeth in the disks are extremely expensive. Furthermore,.itis-very time consuming to machine the radialteeth which form the clutch portionon the disks.
Another structure to secure the disks together toenable the rotor to transmit high torque is-fitted bolt structures disposed in thedisks. However, high. shear: stresses are introducedin the disks becauseof thefitted bolts. Furthermore, because of the hostile environment" in which the bolts are disposed, the disks become ex.-
tremely difficult to disassemble.
Keying structures have also been. suggestedto'prevent rotation ofthe disksto allow the rotorstructureto transmit high torque without: relative. movement between the adjacent' disks. However, keying structures produce notches in the. disks which are already. highlystressed. Furthermore, close tolerances are required resulting in costly manufacturing and assembly of the rotor structure. It would be desirable, then, to. provide an inexpensive, but effective means for transmitting high torquein a rotor structure comprised of' a. plurality of disks and yet have relative ease in assembly. and disassembl y.
SUMMARY OF THE INVENTION The following invention relates to a rotor structure for securing the disksto form a rotor structure which can transmit torque without relative movement of the disks.
In the first embodiment, one of the disksincludes an axially extending ledge portion and the adjacent disk includes a corresponding: matingv surface. Either the ledge or the mating surface has a knurled portion, which under a compressive force embosses the corresponding surface on the adjacent disk. A plurality of: stay bolts are axiallyinsertedthrough the disk to axially secure the disks.
In a second embodiment, a. ring or additional disk structure is inserted between the mating surfaces of the disks, each of the mating surfaces having a knurledpon tion which is embossed on'the ring structure toprevent relative rotation between the disks.
In a third embodiment, a ring, or additionalv disk structure is inserted between the mating'surfaces-on. the
disks, said. ring structure havingknurled portions on each side thereof, the knurled portions being embossed onto the respective mating surfaces of the disks.
What is disclosed, then, is a rotorconstruction comprising azpluralityofdisks, which disks are fastened together by knurledportions which allows a high torque to be transmitted. in the rotor structure. No fittedbolts or key structures which introduce high shear stresses are: used; Furthermore, the knurled portions are rela- 1 tively inexpensive.
DESCRIPTIONIOF THE DRAWINGS FIG; 1" shows-apartial section view of armor structure formed'according to the'principles of the invention;.
FIG-.2is a view taken along line IIII in FIG. 1;
FIG; 3- is an: enlarged sectional view, showing the knurled'portionona disk before assembly;
FIG. 4 is similar to FIG. 3, but showing-another embodiment thereof; and
FIG. 5 is a view similar to FIG. 3, but showing still another embodiment thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG; 13 there is showna rotorstructure It. The rotor structure lflmay be used ona-gas turbine or compressor, the rotor. structure being comprised of a plurality; ofradially extending adjacentdisk structures 121 and 12.0nly the top:half of the rotor structure is shown, since it is: understood that the bottom half is substantiallysimilar' to the upper half. Projectingradiallyoutward from the disk 11: is a plurality of. rotor blades 14, .and correspondingly, projecting radiallyoutward-from. thedisk l2 is-Ia. second=plurality of rotor bI'adeslS. The rotor blades l4and. 15 have root portions.l .7 and 18,,respectively, which are fir tree root in cross .section,.as best seenin FIG. 2. An annular sealing band may. be disposed between the disks l1 and 12 to minimize leakages therethrough.
Inaccordance with. the-principles of the invention, there'is provided anaxially extending ledge portion or spigot22 on rotor disk 11, the spigot 22aaxiallyprojecting-towardsthe adjacent disk l2 'as shown in.FIG. 1'. On disk. 12: isan. axially extending protuberance or ledge portion.24,,which'axially extends towards rotor disk 1.1-. The spigot 22: and protuberance 24-insure concentricity of the disks. 11 and 1-2;.
The radially outer-wall25 of theprotuberance 24, as best seen in FIGS. 1 and 3, is slightly smaller than the radially innerwall 23 0f the spigot 22, thereby allowing the radiallyouter wall25- of the protuberance 24 to be disposed'within the radially inner wall23 of the spigot 22. However, the. radially outer wall of the protuberance: 24* can have a slightly larger diameter than the inner wall-2'3 of the spigot 22to-permit interference in assembly-of the disks such as by. shrink. fitting or press fitting;
The mating surface '26 of the disk II is a radially extending wallsurface, which-extends fromthe ingress27 of thedisk to the radially'inner wall 23 of the spigot 22. The corresponding axial mating surface 28 is on the axialendwall of the protuberance 24 of the disk 12. As seen inFIG'. 1,.the mating surfaces 26.and28.abuteach other.
As showniin FIG. 3(the disks beingshownbefore assembly),.t-here is a knurled portion which is annularly disposed around the mating wall surface 26 on the disk 11. The knurled portion 30, as shown, is comprised of inclined ridges, but, the knurled portion may be of any well known shape. This is more readily seen in FIG. 2, which also shows a knurling tool 32 machining the annular knurling portion 30 on the mating surface 26. As is well known in the art, the process of knurling projects a portion of the material outwardly and depresses a portion of the material inwardly. Therefore, there are axial teeth-like projections extending axially from the knurled portion 30.
After knurling one of the mating surfaces, 26 or 28, the disks l1 and 12 are pressed together by any suitable means well known in the art, such as a hydraulic press (not shown). The axial projecting teeth in the knurling portion 30 are embossed upon the corresponding mating surface 28 or 26. The disks are compressed until the surfaces 26 and 28 abut each other. Because of the friction drive between the disks at the mating smooth surfaces 26 and 28, the knurled teeth portion need not be embossed too deeply into the corresponding mating surface.
A plurality of axially extending apertures 34 and 35 (FIG. 1) are disposed within the disks 11 and 12, respectively, A plurality of stay bolts 37 are inserted therethrough to lock the disks in an axial direction. A further description of the stay bolts 37 can be found in the H. O. Pederson et al. patent previously cited.
Referring to FIG. 4, there is shown a preassembled view of two adjacent disks 39 and 40. An annular ring structure or third disk 42 is disposed between the mating surfaces 44 and 45 of disks 39 and 40, respectively. The ring structure 42 is preferablymade of a material somewhat softer than the disks 39 and 40. The ring structure 42 has two mating surfaces 47 and 48, the mating surface 47 corresponding to the mating surface 44 and the mating surface 48 corresponding to the mating surface 45.
A knurled portion 50 is machined onto the mating surface 44, and is concentric relative to the axis of rotation of the rotor. A second knurled portion 51 is machined onto the mating surface 45 concentric relative to the axis of rotation of the rotor. The disks 39 and 40 and the ring structure 42 are compressed so that the knurled portions 50 and 51 are embossed onto the respective mating surfaces 47 and 48, respectively. Mating surfaces 44 and 47 frictionally abut as do mating surfaces 45 and 48, the knurling portions embossed into the ring structure 42 augmenting the friction drive between the mating surfaces. Again, as in the first embodiment, any suitable means, such as stay bolts, may be used to prevent axial movement between the adjacent disks 39, 40, and 42.
Disk structures 54 and 55 are shown in a preassembled view in FIG. 5. Disposed therebetween is a ring structure or third disk 57, the disks 54, 55, and 57 being disposed adjacent to each other. The ring structure or third disk 57 is preferably made of material which is harder than the disk structures 54 and 55. A radially extending annular mating surface 59 is provided on the structure 54 and a radial extending surface 60 is provided on the axial extending protuberance of the disk structure 55. The ring structure 57 has a mating surface 61 which corresponds with mating surface 59 and a mating surface 62 which corresponds with mating surface 60 on disk 55.
In the embodiment shown in FIG. 5, a knurling tool machines a knurled portion on each of the mating surfaces 61 and 62 of the ring structure 57, the knurled portion being about mid-way between the radially outer and radially inner surfaces of the ring structure. Then, under a compressive force by any suitable means, the disk structures 54 and 55 and the ring structure 57 are compressed under sufficient force so that the mating surfaces 59 and 61 abut, and the mating surfaces 60 and 62 abut. This causes the knurled portions 64 and 65 to emboss onto the relatively softer mating surfaces 59 and 60, respectively. The knurled portions, 64 and 65, augment the friction drive already established between the respective mating surfaces 59 and 61, and 60 and 62.
Although it is desirable that theioriginal knurled face be harder than the face onto which the knurl is to be embossed, this is not essential since a knurled portion could be imprinted on a surface of equal hardness. Furthermore, more than three disks structures can be used.
What is disclosed then is a rotor structure, comprised of a plurality of disks which are fastened together by knurled portions. The knurled portions augment the friction drive between adjacent mating surfaces to allow a high torque to be transmitted in the rotor structure. This eliminates the previously expensive process of using curvic clutches, fitted bolts and key structures.
1. A method of forming a rotor structure comprising the steps of;
1. providing at least two radial extending disk structures;
2. machining a knurled portion on at least one of the mating surfaces of the disk structures;
3. aligning the adjacent disk structures relative to each other in axial and radial directions;
4. compressing the adjacent disk structures to emboss the knurled portion on the other disk structure;
5. and providing means to maintain the disk structures in axial abutment.
2. The method recited in claim 1 and further including the steps of:
l. machining a knurled portion on the mating surface of the other disk structure;
2. providing a third disk structure;
3. and compressing the disk structures to emboss the knurled portions onto the third disk structure.
3. A method of constructing a rotor structure for an elastic fluid utilizing machine comprising the steps of:
1. providing first, second and third disk structures having mating surfaces thereon;
2. machining the mating surfaces of the third disk structure to provide annular knurling portions thereon;
3. positioning the third disk structure between the first and second disk structures;
4. compressing the disk structures to emboss the knurled portion of the third disk structure onto the mating surfaces of the first and second disk structures; and
5. securing the disk structures in an axial direction to prevent axial movement between the disk struc-