US3307252A - Method for providing a narrow flange on a large rotor forging - Google Patents

Method for providing a narrow flange on a large rotor forging Download PDF

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US3307252A
US3307252A US396937A US39693764A US3307252A US 3307252 A US3307252 A US 3307252A US 396937 A US396937 A US 396937A US 39693764 A US39693764 A US 39693764A US 3307252 A US3307252 A US 3307252A
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United States
Prior art keywords
ring
providing
rotor
body portion
forging
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Expired - Lifetime
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US396937A
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Lloyd P Grobel
Forest Durward R De
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General Electric Co
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General Electric Co
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/02—Blade-carrying members, e.g. rotors
    • F01D5/06—Rotors for more than one axial stage, e.g. of drum or multiple disc type; Details thereof, e.g. shafts, shaft connections
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49789—Obtaining plural product pieces from unitary workpiece
    • Y10T29/49796—Coacting pieces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49826—Assembling or joining
    • Y10T29/49863—Assembling or joining with prestressing of part
    • Y10T29/49865—Assembling or joining with prestressing of part by temperature differential [e.g., shrink fit]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49995—Shaping one-piece blank by removing material
    • Y10T29/49996—Successive distinct removal operations

Definitions

  • This invention relates to an improved method for providing a relatively narrow flange on a very large cylindrical forged rotor, such as the kind employed in very.
  • this invention relates to an improved method for providing a narrow flange on a generator rotor when efforts are being made to reduce over-all rough forging weight.
  • the rotor of a steam turbine-generator which carries the filed coils for the generator is commonly manufactured from a cylindrical forging.
  • Such forgings are extremely large and heavy, a typical forging being on the order of 45 feet long and 5 feet in diameter along the body portion, and weighing 160 tons. Due to the nature of the forging process, it is diflicult to forge a relatively narrow flange. Ordinarily it is necessary to forge a relatively wide flange, out of which the narrow flange is rough machined. This often involves filling the space between two flanges with solid metal. Obviously, this procedure adds weight to the forging.
  • Another method used has been to make the flange by manufacturing a separate ring and shrinking it onto a reduced diameter rotor portion to form the narrow flange.
  • the difliculty with the latter method arises when there are other flanges or enlarged diameter portions on either side, since in this case, the shrunk-on ring cannot be passed over the enlarged diameter portions.
  • the present invention is concerned with an improved method for providing a narrow flange on the rotor forging without the necessity for adding additional metal to an already large forging and then having to remove the additional metal during subsequent machining operations.
  • one object of the present invention is to provide an improved method for furnishing a relatively narrow flange on a very large rotor forging, without hav ing to add rough forging metal and then remove same.
  • a more specific object of the invention is to provide an improved method for furnishing a fan ring on a large generator rotor.
  • FIG. 1 is a perspective view of a complete generator rotor forging during one stage of manufacture
  • FIG. 2 is an enlarged view, taken in cross section, of one end of the forging of FIG. 1 after rough machining
  • FIG. 3 is an enlarged view, taken in cross section, illustrating the generator rotor of FIG. 2 at a later stage of manufacture.
  • the invention is practiced by providing additional metal on some other convenient rotor portion lying adjacent the desired location of the narrow flange, cutting a hollow ring from one side of this rotor portion, moving the ring axially to the new location on the rotor, and attaching the ring to the rotor, such as by shrink fit.
  • the rotor includes a central body portion 1 with spindle portions 2.
  • the spindle portions include intermediate diameter sections 2a and small diameter sections 2b, the latter being adapted to support the rotor in bearings (not shown).
  • One end of the generator rotor normally terminates in a stub 3, which is coupled to the exciter, .while the other end comprises a coupling flange 4 for attachment to a similar steam turbine shaft coupling flange (not shown).
  • the body portion 1 may have longitudinal winding slots machined in the rotor at this stage, but these are omitted in order to avoid obscuring the invention.
  • the rotor In the case of gas-cooled generators, the rotor normally includes fan blades mounted on relatively narrow flanges 5, 6 at opposite ends of the rotor called fan rings. Also shown are centering rings 7, 8 which are not attached to the intermediate spindle portion 2a, but which will be later attached to a retaining ring holding the electrical windings in place.
  • centering ring 8 can be passed over the extending stub 3 with no difliculty. Also, fan ring 6 can be placed over stub 3 and attached to intermediate shaft portion 2a with a shrink fit, if desired.
  • the section of the rough-machined forging shows the body portion 1
  • an extra metal portion 4a is added above and beyond that which would be required for coupling flange 4.
  • the axial length of portion 4a is just suflicient for the fan ring and the parting tool which will later separate it from coupling flange 4.
  • the body portion 1 is increased in an axial dimension with an additional metal portion 1a, to provide sufficient width for a centering ring.
  • the final positions to be occupied by the fan ring and centering ring are shown in phantom lines at 5', 7'.
  • the cutting of the rings 5, 7 is afforded by means of well-known machining techniques. Radial and axial parting cuts are made into the coupling flange as it appears in FIG. 2 in order to separate portion 4a. This is then moved axially where it is shrunk onto the intermediate shaft portion 2a to become the fan ring 5. Additional machining operations may then be performed on the fan ring.
  • FIG. 3 shows the fan blades 9 attached to the fan ring and also shows the retaining ring 10 as it is attached to the centering ring.

Description

March 7, 1967 L. P. GROBEL ETAL METHOD FOR PROVIDING A NARROW FLANGE ON A LARGE ROTOR FORGING Filed Sept. 16, 1964 F |G.l
INVENTORSI LLOYD P. GROBEL, DURWARD R. DeFOREST, BY 4] W THEIR ATTORNEY.
United States Patent 3,307,252 METHOD FOR PROVIDING A NARROW FLANGE ON A LARGE ROTOR FORGING Lloyd P. Grobel and Durward R. De Forest, Schenectady,
N.Y., assignors to General Electric Company, a corporation of New York Filed Sept. 16, 1964, Ser. No. 396,937
3 Claims. (Cl. 29416) This invention relates to an improved method for providing a relatively narrow flange on a very large cylindrical forged rotor, such as the kind employed in very.
large rotating equipment used in steam turbine-generator powerplants. More, particularly, this invention relates to an improved method for providing a narrow flange on a generator rotor when efforts are being made to reduce over-all rough forging weight.
The rotor of a steam turbine-generator which carries the filed coils for the generator is commonly manufactured from a cylindrical forging. Such forgings are extremely large and heavy, a typical forging being on the order of 45 feet long and 5 feet in diameter along the body portion, and weighing 160 tons. Due to the nature of the forging process, it is diflicult to forge a relatively narrow flange. Ordinarily it is necessary to forge a relatively wide flange, out of which the narrow flange is rough machined. This often involves filling the space between two flanges with solid metal. Obviously, this procedure adds weight to the forging.
Another method used has been to make the flange by manufacturing a separate ring and shrinking it onto a reduced diameter rotor portion to form the narrow flange. The difliculty with the latter method arises when there are other flanges or enlarged diameter portions on either side, since in this case, the shrunk-on ring cannot be passed over the enlarged diameter portions.
As rotor forgings have reached extremely large diameter and weight, every eflfort is made to design the rough forging in such a way as to reduce the amount of metal. The present invention is concerned with an improved method for providing a narrow flange on the rotor forging without the necessity for adding additional metal to an already large forging and then having to remove the additional metal during subsequent machining operations.
Accordingly, one object of the present invention is to provide an improved method for furnishing a relatively narrow flange on a very large rotor forging, without hav ing to add rough forging metal and then remove same.
A more specific object of the invention is to provide an improved method for furnishing a fan ring on a large generator rotor.
Other objects and advantages will be apparent from the following description, taken in connection with the accompanying drawing, in which:
FIG. 1 is a perspective view of a complete generator rotor forging during one stage of manufacture,
FIG. 2 is an enlarged view, taken in cross section, of one end of the forging of FIG. 1 after rough machining, and
FIG. 3 is an enlarged view, taken in cross section, illustrating the generator rotor of FIG. 2 at a later stage of manufacture.
Briefly stated, the invention is practiced by providing additional metal on some other convenient rotor portion lying adjacent the desired location of the narrow flange, cutting a hollow ring from one side of this rotor portion, moving the ring axially to the new location on the rotor, and attaching the ring to the rotor, such as by shrink fit.
Referring to FIG. 1 of the drawing, a perspective view is shown of a forging in an intermediate stage of manufacture. The rotor includes a central body portion 1 with spindle portions 2. The spindle portions include intermediate diameter sections 2a and small diameter sections 2b, the latter being adapted to support the rotor in bearings (not shown). One end of the generator rotor normally terminates in a stub 3, which is coupled to the exciter, .while the other end comprises a coupling flange 4 for attachment to a similar steam turbine shaft coupling flange (not shown). The body portion 1 may have longitudinal winding slots machined in the rotor at this stage, but these are omitted in order to avoid obscuring the invention.
In the case of gas-cooled generators, the rotor normally includes fan blades mounted on relatively narrow flanges 5, 6 at opposite ends of the rotor called fan rings. Also shown are centering rings 7, 8 which are not attached to the intermediate spindle portion 2a, but which will be later attached to a retaining ring holding the electrical windings in place.
Observing the right-hand end of the rotor, it will be seen that centering ring 8 can be passed over the extending stub 3 with no difliculty. Also, fan ring 6 can be placed over stub 3 and attached to intermediate shaft portion 2a with a shrink fit, if desired.
Observing the other end of the rotor, however, it will be seen that rings 5, 7 will not pass over the integral coupling flange 4. It is undesirable to make the coupling flange out of a separate ring because of the torsional stress it will undergo in operation. Although flange 5 could be forged in the location shown, considerable unusable metal would have to be added to the rough forging to do this. The weight of this unusable metal is substantial and may become prohibitive if forging capacity is a limiting factor of design.
Referring now to FIG. 2 of the drawing, the section of the rough-machined forging shows the body portion 1,
the intermediate shaft spindle portion 2a, the small diameter spindle portion 2b, and the coupling flange 4.
In accordance with the invention, an extra metal portion 4a is added above and beyond that which would be required for coupling flange 4. The axial length of portion 4a is just suflicient for the fan ring and the parting tool which will later separate it from coupling flange 4. Similarly, the body portion 1 is increased in an axial dimension with an additional metal portion 1a, to provide sufficient width for a centering ring. The final positions to be occupied by the fan ring and centering ring are shown in phantom lines at 5', 7'.
Referring now to FIG. 3 of the drawing, the fan ring 5 and centering ring 7 are shown in their final positions. The metal which has been removed from the coupling flange 4 and body portion 1 is now indicated by phantom lines at 4a and 1a.
The cutting of the rings 5, 7 is afforded by means of well-known machining techniques. Radial and axial parting cuts are made into the coupling flange as it appears in FIG. 2 in order to separate portion 4a. This is then moved axially where it is shrunk onto the intermediate shaft portion 2a to become the fan ring 5. Additional machining operations may then be performed on the fan ring.
Similarly, the ring which is parted from the body portion out of metal 1a now becomes a centering ring 7. Although not material to the present invention, FIG. 3 shows the fan blades 9 attached to the fan ring and also shows the retaining ring 10 as it is attached to the centering ring.
Other variations of the invention will become apparent to those skilled in the art. For example, it should be apparent that both the fan ring 5 and centering ring 7 could be obtained from the coupling flange if desired. However, due to the fact that centering ring 7 is of greater diameter, it is most conveniently obtained from the body portion.
providing extra metal on said couplingflange having a widthslightly greater than the width of said fan ring, and also providing extra metal on the body portion having a width slightly greater than that of said centering ring, providing a fan ring by making radial and axial cuts into said extra metal portion of the coupling flange, providing a centering ring by making radial and axial cuts into said extra metal on the body portion, moving said fan ring axially to a location separated from the body portion by the centering ring and attaching it to said rotor spindle portion, whereby the centering ring is disposed between the fan ring and the body portion.
2. The method of providing a relatively narrow flange on a large cylindrical forging having two enlarged diameter portions separated by a reduced diameter portion :omprising the steps of:
providing an extra axial length of metal on one of said enlarged diameter portions having a width slightly greater thanthe desired width of said flange,
true spirit and scope of removing a ring from said enlarged diameter portion by making radial and axial parting cuts into said extra metal portion,
moving said ring axially to another location between said enlarged diameter portions, and
attaching said ring to said reduced diameter portion to provide a narrow flange thereon.
3. The method of providing a relatively narrow flange on a cylindrical rotor forging having two enlarged diameter portions separated by a reduced diameter portion comprising the steps of:
providing extra metal on one of said enlarged diameter portions having a width slightly greater than the desired width of said flange,
removing a hollow ring from the first enlarged diameter portion by making radial and axial parting cuts into said extra metal portion,
moving said ring axially to a location adjacent an enlarged diameter portion, and
shrinking said ring onto the reduced diameter portion to provide a narrow flange thereon.
References Cited by the Examiner UNITED STATES PATENTS 7/1932 Gundersen et a1. 10-10 1/1951 Brown 29447

Claims (1)

1. THE METHOD OF PROVIDING A FAN RING AND A CENTERING RING ON A GENERATOR ROTOR FORGING HAVING A BODY PORTION AND A COUPLING FLANGE SPACED BY A REDUCED DIAMETER SPINDLE PORTION, COMPRISING THE STEPS OF: PROVIDING EXTRA METAL ON SAID COUPLING FLANGE HAVING A WIDTH SLIGHTLY GREATER THAN THE WIDTH OF SAID FAN RING, AND ALSO PROVIDING EXTRA METAL ON THE BODY PORTION HAVING A WIDTH SLIGHTLY GREATER THAN THAT OF SAID CENTERING RING, PROVIDING A FAN RING BY MAKING RADIAL AND AXIAL CUTS INTO SAID EXTRA METAL PORTION OF THE COUPLING FLANGE, PROVIDING A CENTERING RING BY MAKING RADIAL AND AXIAL CUTS INTO SAID EXTRA METAL ON THE BODY PORTION, MOVING SAID FAN RING AXIALLY TO A LOCATION SEPARATED FROM THE BODY PORTION BY THE CENTERING RING AND ATTACHING IT TO SAID ROTOR SPINDLE PORTION, WHEREBY THE CENTERING RING IS DISPOSED BETWEEN THE FAN RING AND THE BODY PORTION.
US396937A 1964-09-16 1964-09-16 Method for providing a narrow flange on a large rotor forging Expired - Lifetime US3307252A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1868415A (en) * 1929-10-31 1932-07-19 Gundersen Einar Method of manufacturing screws with one or two appending washers
US2539056A (en) * 1944-09-02 1951-01-23 Chicago Pneumatic Tool Co Method of assembling tool joints

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1868415A (en) * 1929-10-31 1932-07-19 Gundersen Einar Method of manufacturing screws with one or two appending washers
US2539056A (en) * 1944-09-02 1951-01-23 Chicago Pneumatic Tool Co Method of assembling tool joints

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