Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
  • G01B5/20—Measuring arrangements characterised by the use of mechanical techniques for measuring contours or curvatures
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
  • G01B5/24—Measuring arrangements characterised by the use of mechanical techniques for measuring angles or tapers; for testing the alignment of axes
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
  • G01B5/20—Measuring arrangements characterised by the use of mechanical techniques for measuring contours or curvatures
  • G01B5/205—Measuring arrangements characterised by the use of mechanical techniques for measuring contours or curvatures of turbine blades or propellers

Definitions

• This invention relates to turbines and, more particularly, to a gage for determining the radial align ⁇ ment of turbine blades on a turbine rotor.
• the attachment structure comprises a Christmas tree shaped root structure which slides into a mating slot in the rotor. When the blade is properly positioned, lugs extending from opposing sides of the root structure -share equally in retaining the blade in the rotor.
• lugs on one side of the root structure may support more stress forces than those on the opposite side leading to potential overstress conditions and damage. Accordingly, it is desirable to assure that turbine blades are aligned with their respective centerlines oriented along radial lines of the turbine rotor. It is a primary object of invention to provide an improved gage for determining radial alignment of turbine blades on a turbine rotor.
• the present invention resides in apparatus for determining radial alignment of turbine blades on a turbine rotor by in situ measurement of blade alignment with respect to the surface of the rotor, each of the blades including a root structure for supporting the blade in a matching groove in the rotor, a platform attached to the root structure and an airfoil extending radially outward from the platform and terminating in an integral shroud portion characterized by an elongated base member having substantially parallel- upper and lower surfaces; first and second elevated contact points formed in spaced apart relationship on the lower surface of said base member, said contact points being adapted to support said base member adjacent the rotor and in a plane substantially parallel to a tangent line to the rotor surface; a standard having one end fixedly connected to said base member, said standard extending ' radially outward with respect to the rotor; a third contact point extending from said standard and positioning for contacting the blade platform when the apparatus is in a measuring
• Fig. 1 is a partial sectional view of a circular array of rotatable blades disposed in a rotor;
• Fig. 2 is an axial view of an integral shroud blade
• Fig. 3 is a radial view of an integral shroud blade
• Fig. 4 is a tangential view of an integral shroud blade
• Fig. 5 is an axial view of an exemplary form of the inventive gage in operative position with a turbine blade
• Fig. 6 is a tangential view of another form of the inventive gage in operative position with a turbine blade;
• Fig. 7 is a radial view of the inventive gage of
• Fig. 8 is an elevational view illustrating one method of calibration of an illustrative form of the inventive gage. Referring now to the drawings in general and in particular to Fig. 1, there is shown a portion of a circum ⁇ ferential array of exemplary turbine blades 1 disposed in a portion of a turbine rotor 3.
• each turbine blade comprises a Christmas tree shaped root structure 5 which registers with a similarly shaped groove or slot in the rotor 3 to fasten the blades 1 to the rotor 3.
• a pin fits a semicircular groove 7 in the blade 1, which regis- ters with a semicircular groove in the rotor 3 (not shown) .
• the root portion 5 extends from a blade platform 6.
• an airfoil shaped blade portion 9 having leading and trailing edges 11 and 13, respectively.
• a shroud portion 15 Disposed radially outwardly of the blade portion 9 and made integral therewith is a shroud portion 15.
• the shroud portion 15 has a leading planar surface 17 and a trailing planar surface 19.
• the leading planar surface 17 as indicated by the line 20 which represents the extension of the planar surface 17 is generally parallel to an axial radial pJLane 21 passing, through the center portion. (.” b i a d- e centerline”) of the root structure 5 (sometimes referred to as 'root 5').
• the trailing planar surface 19 if extended as indicated at 23 forms an angle "a" with, the radial axial plane generally equal in degrees to 350 divided by the number of blades in the circular array.
• the leading planar surface 17 extends beyond the leading edge of the blade portion 9 and the trailing edge 13 of the blade portion 9 extends substantially beyond the trailing planar surface 23 of the shroud portion 15.
• the outer periphery of the shroud portion 15 is machined to form a cylindrical ring which cooperates with labyrinth seals to form a rotating seal.
• Each of the blades 1 is desirably aligned on a radial line of the rotor 3, or, more specifically, the blade centerline 21 desirably coincides with a radial line of rotor 3.
• each lug 25 on root 5 shares equally the centrifugal forces and stresses on blades 1 during turbine operation. If one of the blades 1 is misaligned, its root 5 may be stressed off-center causing a " .rce increase on one or more lugs 25 on one side of the r t. Such force increase may exceed the stress capability of the root structure resulting in blade root damage and may damage the rotor slot in which the blade roots are retained. Since blade separation, whether from root failure or rotor slot failure, can be disastrous in a turbine, it is desirable to assure proper blade alignment at time of assembly.
• FIG. 5 is a simplified view looking axially along the rotor surface and shows a blade 1 in phantom lines with a left- hand form of the invention.
• the invention comprises a gage 27 having an elongated base member 29 and a standard 31 extending, in the exemplary embodiment, substantially perpendicularly from the base member. While shown centered and therefo.re extending, perpendicularly, . it will be app.ar- ent that standard 31 is merely a support structure and need only extend radially outward with respect to the rotor 3.
• First and second elevated contact points in the form of tooling balls 33, 35 are attached in spaced apart relation ⁇ ship to a lower surface of the member 29.
• the tooling balls well known in the machinist's art, provide contact points between the gage and the surface of rotor 3 and support the member 29 adjacent the rotor 3 and in a plane substantially parallel to a tangent line to the rotor surface.
• the contact points at the tooling ball/rotor surface interface are such that a line between the contact points at the interface is" perpendicular to a radial line of the rotor and therefore parallel to a tangent line to the rotor surface.
• the balls 33, 35 may be attached to member 29 in a manner well known in the art such as, for example, by being drilled and tapped and connected by screw-type studs.
• the standard 31 has one end fixedly attached to member 29 by bolts or welds (not shown) .
• both member 29 and standard 31 are preferably formed or machined as elongated bars having substantially parallel opposing surfaces 30, 32 and 34, 36, respectively.
• Standard 31 supports an arm member 37 extending from a lower portion thereof and carrying a tooling ball 39.
• the arm member 37 is positioned such that the tooling ball 39 creates a third contact point for contacting surface 8 of blade platform 6 when the gage is in a measur ⁇ ing position.
• platform 6 is a precision machined portion of the blade 1 and is carefully situated with respect to root 5, surface 8 being machined parallel to blade centerline 21.
• a second arm 41 which supports a measuring apparatus 43 illustrated as a dial indicator gage, some ⁇ times referred to as a dial micrometer.
• the dial indicator apparatus 43 includes a dial indicator 44 and a reciprocat ⁇ ing plunger 45.
• the arm 41 supports the apparatus 43 such that ' plunger 45 is brought into contact with an edge surface 17 of shroud portion 15 of blade 1 when the gage is in the measuring position.
• the apparatus 43 is calibrated with respect to the third contact point so that any devia ⁇ tion of the alignment of blade 1 from a rotor radial line through the center of the blade root will result in a non-zero reading.
• Shroud portion 15 is a precision ma ⁇ chined portion of the blade 1 and the surface 17 contacted by plunger 45 is machined parallel to the axial radial plane 21.
• Both arms 37 and 41 may be attached to standard 31 by bolts or screws such as those indicated at 47 and 49 although other forms of fixedly attaching the arms to standard 31 may be used.
• the arms 37 and 41 are shown as L-shaped in Figs. 5-7, straight arms could be employed by merely changing the form and/or points of attachment.
• a set screw 50 provides support for arm 41.
• FIG. 8 there is illustrated an apparatus for calibrating the gage 27.
• a gage calibra- tion stand 51 comprising a base 53 and a perpendicular member 55 is used to establish zero calibration of dial indicator 43.
• the base 53 has a precision machined flat top surface 57.
• Member 55 is attached to base 53 to form a perpendicular reference.
• the gage 27 is placed on surface 57 and positioned with tooling ball 39 in -contact with member 55.
• various thickness shims 59 are positioned between member 55 and plunger 45 of indicator 43. The shims 59 are preselected to accommodate different dimension shroud portions 15 or offsets of shroud portions 15 from platform portions 6.
• gage 27 With the gage 27 in position against member 55, a bezel lock 61 is released to allow bezel 63 on dial indicator 43 to be turned for setting a zero reading. Lock 61 is then tightened. This completes the calibration of gage 27 and prepares it for use in determining alignment of blades. 1 on a rotor. 3.
• the method of determining blade alignment can be appreciated by reference to Figs. 5-6.
• the gage 27 is placed on a rotor 3 adjacent to one of the blades 1.
• the tooling balls 33, 35 rest on the rotor surface and assure alignment of the gage 27 with a rotor radius.
• the rotor surface includes a plurality of alternat ⁇ ing lands and valleys (shown in Fig.
• the gage 27 is positioned for use on the rotor surface in a valley adja- cent a blade 1 to be measured.
• the gage 27 is moved circumferentially on the rotor surface until the tooling ball 39 contacts blade platform 6.
• an elastic cord 65 for example, may be wrapped around the rotor 3 and over base member 29.
• a retaining member 66 attached to base member 29 having a double folded lip for engaging and slidably holding cord 65.
• the gage 27 thus assures alignment of a center- line axis 21 of a turbine blade 1 with one preselected radial line (the radial line through blade root 5) of the turbine rotor 3 when the blade 1 is mounted in an assembly position in a rotor slot (as shown in Fig. 1) and extending radially outwardly from a circumferential surface of the rotor 3.
• the base member 29 and its tooling balls 33 and 35 along with standard 31 comprise adjustable means for engagement with the circumferential surface of the rotor 3 and permit adjustable movement on the rotor with respect to the blade 1 when blade 1 is in its assembly position.
• the arm 37 and tooling ball 39 comprise means conjointly movable with the adjustable means for engagement with a part of ,th.e blade, preferably the platform 6, when .the blade 1 is in the assembly position.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• A Measuring Device Byusing Mechanical Method (AREA)
• Length-Measuring Instruments Using Mechanical Means (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=25433677

Family Applications (1)

Country Status (8)

Families Citing this family (30)

Citations (3)

Family Cites Families (7)

• 1986
  • 1986-09-30 US US06/913,881 patent/US4718172A/en not_active Expired - Lifetime
• 1987
  • 1987-07-22 IN IN564/CAL/87A patent/IN165247B/en unknown
  • 1987-08-21 WO PCT/US1987/002088 patent/WO1988002472A1/en unknown
  • 1987-09-16 CN CN87106358A patent/CN1014824B/zh not_active Expired
  • 1987-09-17 CA CA000547165A patent/CA1283532C/en not_active Expired - Lifetime
  • 1987-09-29 ES ES8702779A patent/ES2008243A6/es not_active Expired
  • 1987-09-30 JP JP62244445A patent/JPS6390701A/ja active Pending
• 1988
  • 1988-05-28 KR KR1019880700597A patent/KR880701861A/ko not_active Application Discontinuation

Patent Citations (3)

Non-Patent Citations (1)

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