U.S. patent application number 11/087029 was filed with the patent office on 2006-09-28 for nondestructive inspection heads for components having limited surrounding space.
This patent application is currently assigned to Siemens Westinghouse Power Corporation. Invention is credited to James A. Bauer, Michael F. Fair, Michael J. Metala, Charles Crawford Moore, Michael Charles Moore.
Application Number | 20060213274 11/087029 |
Document ID | / |
Family ID | 36645711 |
Filed Date | 2006-09-28 |
United States Patent
Application |
20060213274 |
Kind Code |
A1 |
Moore; Charles Crawford ; et
al. |
September 28, 2006 |
Nondestructive inspection heads for components having limited
surrounding space
Abstract
An inspection head where non-destructive inspection is
structured to fit into narrow spaces, and to accurately and
repeatably move an inspection probe along a surface to be
inspected. Movement of the inspection head along an X, Y, Z,
.THETA., and .PHI.-axis is precisely controlled by individual drive
mechanisms.
Inventors: |
Moore; Charles Crawford;
(Hibbs, PA) ; Moore; Michael Charles; (Hibbs,
PA) ; Fair; Michael F.; (Oakmont, PA) ; Bauer;
James A.; (Gibsonia, PA) ; Metala; Michael J.;
(Murrysville, PA) |
Correspondence
Address: |
Siemens Corporation;Intellectual Property Department
170 Wood Avenue South
Iselin
NJ
08830
US
|
Assignee: |
Siemens Westinghouse Power
Corporation
|
Family ID: |
36645711 |
Appl. No.: |
11/087029 |
Filed: |
March 22, 2005 |
Current U.S.
Class: |
73/618 ; 73/641;
73/644; 73/866.5 |
Current CPC
Class: |
G01N 2291/269 20130101;
G01N 27/902 20130101; G01N 29/225 20130101; G01N 29/265 20130101;
G01N 2291/101 20130101 |
Class at
Publication: |
073/618 ;
073/866.5; 073/644; 073/641 |
International
Class: |
G01N 29/265 20060101
G01N029/265; G01N 29/28 20060101 G01N029/28; G01N 27/90 20060101
G01N027/90 |
Claims
1. A nondestructive inspection head, comprising: means for raising
and lowering the head into a location to be inspected; an X-axis
drive; a drive selected from the group consisting of a Y-axis drive
and a .PHI.-axis drive; and a sensor.
2. The inspection head according to claim 1, further comprising a
Z-axis drive.
3. The inspection head according to claim 2, wherein the Z-axis
drive includes a motor structured to drive the head in a first
direction, and a spring structured to drive the head in an opposing
direction.
4. The inspection head according to claim 3, further comprising: a
plurality of interconnected, substantially parallel slides adjacent
to each other and structured to slide with respect to each other;
an arm structured to actuate sliding motion of the sliders; a
spring structured to bias the arm in a first direction; and a
motor-driven pulley structured to move the arm in the opposing
direction.
5. The inspection head according to claim 1, further comprising a
.theta.-axis drive.
6. The inspection head according to claim 5, wherein the
.theta.-axis drive includes a motor-driven belt, with the belt
driving a leadscrew operatively connected to a gear that is
operatively connected to the head.
7. The inspection head according to claim 1, wherein the X-axis
drive includes a lead screw actuated by a motor-driven pulley.
8. The inspection head according to claim 1, further comprising a
probe holder structured to hold a probe in a floating manner.
9. The inspection head according to claim 1, wherein the probe is
selected from the group consisting of ultrasound and eddy
current.
10. The inspection head according to claim 9, further comprising a
pair of ultrasonic probes.
11. The inspection head according to claim 9, further comprising a
means for dispensing a coupling media around an ultrasonic
sensor.
12. The inspection head according to claim 11: wherein the coupling
media is water; and further comprising a catch basin and holding
tank structured for recycling the water.
13. The inspection head according to claim 1, further comprising at
least two rollers structured to engage a surface of a component
being inspected.
14. The inspection head according to claim 1, wherein the probe is
secured within a probe housing, and the probe is spring-biased away
from the probe housing.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to non-destructive inspection
of turbine components. More specifically, the invention provides
inspection heads for positioning sensing elements on the surface of
turbine rotor discs on either a fully assembled rotor or on discs
that have been removed from the rotor in a controlled, repeatable
manner.
[0003] 2. Description of the Related Art
[0004] The blades of steam turbines are attached to discs and are
subjected to significant stress due to the heat, pressure, and
vibrations within their operating environments. It is therefore
necessary to periodically inspect these discs for surface cracking,
internal cracking, and pitting at the blade attachment area and the
rotor attachment area, known as the disc bore. If such inspections
locate indications of defects beginning to form that are not
sufficient to take the disc out of service, it is desirable to
ensure that later inspections focus on locations within the discs
where the indications were found in the previous inspection.
[0005] Turbine discs are presently inspected using sensing elements
such as ultrasonic probes and eddy current probes, the operation of
which is well known in the art. Presently used probes are hand
held, thereby limiting the positional accuracy of the inspection,
and the repeatability with which the probes may be positioned.
[0006] Accordingly, there is a need for a means of accurately and
repeatably positioning an inspection probe in a desired location
with respect to a turbine disc. There is an additional need for
such probes to fit within the small space available between discs
within a typical turbine rotor assembly, thereby avoiding a need to
remove the discs from the turbine for inspection.
SUMMARY OF THE INVENTION
[0007] The present invention provides a non-destructive inspection
head that is particularly useful for inspecting the discs of
turbines, and particularly the high stress areas, such as the blade
attachment area and the disc bore area (where the disc is attached
to the rotor using a "shrink fit" process for steam turbines.
[0008] For purposes of this description, the X-axis is defined as
an axis substantially horizontal and substantially parallel to a
disc being inspected. The Y-axis is defined as an axis that is
substantially vertical, and also substantially parallel to a disc
being inspected. The Z-axis is defined as an axis that is
substantially horizontal, and substantially perpendicular to a disc
being inspected. The .THETA.-axis is defined by rotation about the
Z-axis. Lastly, the .PHI.-axis is defined by rotation around the
X-axis.
[0009] The invention is structured to place an inspection probe,
for example, an ultrasonic probe or an eddy current probe, adjacent
to or against a disc to be inspected, while the disc remains
mounted to a rotor. The turbine blades may or may not be attached
to the disc during the inspection. The probe may be raised between
the discs, and adjacent to the disc to be inspected, by presently
available devices. As it is currently designed, one probe and head
assembly is positioned on either side of the disc to be inspected.
This provides a complete inspection without moving the base unit.
Once the inspection head is properly positioned, the head itself is
structured for movement along at least some of the X axis, Y axis,
Z axis, .THETA.-axis and .PHI.-axis. Movement along each of these
axes is controlled by a separate drive mechanism, so that the probe
may move independently along any axis, or along more than one axis,
as necessary to properly position the probe. The .THETA.-drive and
consequentially the probe are free floating in a semi-spherical
area atop the Z-drive, which allows for proper contact of the face
of the probe to the disc over the various ranges of disc geometry
and probe contact face contours.
[0010] If an ultrasound probe is used, a delivery/recirculation
system for an ultrasonic coupling medium, for example, water, may
also be provided. The system is structured to dispense water
between the propad and the component to be expected, thereby
providing effective ultrasonic coupling between the probe and the
component. A catch basin is located below the component, for
catching the water so that it may be recirculated throughout the
inspection process.
[0011] The inspection heads may be configured specifically to
inspect specific discs on a turbine rotor assembly. For example, a
linear drive head providing for movement along only the X and Y
axes may be utilized for inspections near the blade attachment
region, where the surfaces may be inspected along a straight line,
and where the Jack of Z and .THETA. drive mechanisms enables the
inspection head to be smaller, better fitting within tight spaces.
An arc drive head having an X axis drive and a .PHI.-axis drive may
be utilized to inspect discs having a curved geometry. A standard
head, having X-axis, Y-axis, Z-axis, and .THETA.-axis drives may be
utilized to scan disc in the bore region, where the disc contacts
the rotor, and is particularly useful for inspecting regions of
turbine discs from the blade attachment area to the disc bore
regions. Lastly, a low clearance head having X-axis, Y-axis,
Z-axis, and .THETA.-axis drives, but with a more limited range of
motion along the X-axis than the standard head, may be utilized
where the minimum gap between discs is less than that which will
accommodate a standard head. The use of an inspection head having
precisely controlled positioning means ensures that the inspection
head may be located accurately and repeatably where inspections are
desired. For example, if an indication was found in a specific
location in a prior inspection, but the indication was not
sufficient to take the disc out of service, the inspection head may
be accurately directed to the location where the indication
appeared during a subsequent inspection.
[0012] Accordingly, it is an object of the present invention to
provide an inspection head capable of accurately and repeatably
positioning a non-destructive inspection probe against a component
to be inspected.
[0013] It is another object of the invention to provide an
inspection head having independently and precisely controlled drive
systems for each axis of movement.
[0014] It is a further object of the invention to provide an
inspection head that includes or omits specific drive mechanisms
and specific directions, permitting construction of an inspection
head that may fit within a narrow space in a desired location,
while still providing the necessary range of motion to complete an
inspection.
[0015] It is another object of the invention to provide an
inspection head that may be utilized with one or two inspection
probes.
[0016] It is a further object of the invention to provide an
inspection head whose range of motion and precise control of
positioning enable both straight on and angled directional
inspections, thereby permitting an indication detected by a
straight on inspection to be more precisely located using the
angled inspection.
[0017] It is a further object of the invention to provide an
inspection head that may be precisely positioned so that
indications may be precisely located during pitch catch ultrasonic
inspections.
[0018] It is a further object of the invention to provide an
inspection head that may be used interchangeably with a wide
variety of non-destructive inspection probes, for example, single
ultrasonic, double ultrasonic, phased array ultrasonic, or eddy
currents.
[0019] These and other objects of the invention will become more
apparent through the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is an isometric back view of a standard inspection
head according to the present invention, illustrating two
inspection probes thereon.
[0021] FIG. 2 is an isometric back view of a standard inspection
head according to the present invention, illustrating a single
inspection probe therein.
[0022] FIG. 3 is an isometric, partially exploded back view of the
upper portion of an inspection head according to FIG. 2.
[0023] FIG. 4 is an isometric, partially exploded back view of an
inspection probe assembly according to the present invention.
[0024] FIG. 5 is an isometric, partially exploded back view of an
X-axis drive mechanism for use with the inspection head of FIG.
2.
[0025] FIG. 6 is a partially exploded, isometric back view of a
Y-axis drive mechanism for use with an inspection head of FIG.
2.
[0026] FIG. 7 is an isometric, back view of a low clearance
inspection head according to the present invention.
[0027] FIG. 8 is an isometric, partially exploded back view of an
upper portion of a low clearance inspection head according to FIG.
7.
[0028] FIG. 9 is an isometric back view of an inspection probe
utilized with the inspection head of FIG. 7.
[0029] FIG. 10 is an isometric, partially exploded back view of
upper portion of an arc drive inspection head according to the
present invention.
[0030] FIG. 11 is an isometric view of a pair of linear drive
inspection heads according to the present invention.
[0031] FIG. 12 is an isometric, partially exploded back view of an
upper portion of a linear drive inspection head according to the
present invention.
[0032] FIG. 13 is a back view of an inspection head and inspection
head lifting mechanism according to the present invention.
[0033] FIG. 14 is an environmental, isometric side view of an
inspection head according to the present invention being utilized
to perform an inspection on the discs of a fully assembled steam
turbine rotor.
[0034] FIG. 15 is a back view of an inspection head and inspection
head lift mechanism according to the present invention, being
utilized to perform an inspection.
[0035] FIG. 16 is a side view of a pair of arc drive inspection
heads performing an inspection on a disc of a steam turbine rotor
assembly.
[0036] FIG. 17 is an isometric view of a pair of linear drive
inspection heads according to the present invention as configured
to perform an inspection on both sides of a disk
simultaneously.
[0037] Like reference characters denote like elements throughout
the drawings.
DETAILED DESCRIPTION
[0038] The present invention provides an inspection head for
delivering non-destructive inspection probes to locations having
limited spaces for such probes, for example, between adjacent discs
of a turbine rotor assembly for inspection of the surfaces of those
discs.
[0039] Referring to FIGS. 1-6, the first embodiment of the
inspection head is illustrated, hereinafter called a standard head
10. Referring to FIGS. 1-2, the standard head 10 includes a base 12
(partially shown) structured for mounting on a presently available
apparatus for raising the inspection head between adjacent discs.
Although such devices are presently available, they will be briefly
described below. A stand 14 extends upward from the base 12. The
stand 14 terminates in a rail support plate 16. The rail support
plate 16 supports a pair of rails 18 on either side of a drive
screw 20, with an endcap 22 on either end of the assembly. The
drive screw 20 is rotably secured between the endcaps 22, with an
X-axis drive mechanism 24, which will be described in greater
detail below, operatively connected to one end of the drive screw
20.
[0040] The stand 14 further includes a Y-axis drive mechanism 26,
including a fixed vertical rail 28 having a bracket 30 secured at
its top end. A pair of sliders 32 are slidably mounted on the rail
28, with an arm 34 extending upward from each slider 32 to the rail
support plate 16. In addition to the movement of the rail support
plate 16 with respect to the base 12, the individual probe
assemblies 36 may move vertically with respect to the rail support
plate 16. A motor driven screw rail 38, the operation of which will
be described below, provides for vertical positioning adjustment of
each probe assembly 36.
[0041] The standard head 10 is illustrated in more detail in FIGS.
3-6. Referring specifically to FIGS. 2 and 5, the drive screw 20 is
controlled by the X-axis drive motor 40. The X-axis drive motor 40
is mounted to a motor mount 42 which is secured below one of the
two end caps 22. The motor 40 is connected through the bushing 44
to the pulley 46, which drives the drive belt 48, thereby turning
the pulley 50. The pulley 50 is connected to the drive screw 20
through the thrust bearings 52 and ball bearings 54, thereby
facilitating rotation within the hole 56 defined within the end cap
22.
[0042] Referring to FIGS. 2 and 6, the Y-axis drive mechanism 26 is
illustrated in more detail. The Y-axis motor 58 is secured to the
motor mount 60. The Y-axis motor 58 is operatively connected to the
Y-axis drive screw 38 through the thrust bearing 62, miter gear 64,
miter gear 66, and thrust bearing 68, with the interaction of the
two miter gears 64, 66 inverting the horizontal rotation imparted
by the motor 58 to the vertical rotation necessary to rotate the
drive screw 38.
[0043] Referring to FIGS. 2-4, a probe assembly 36 is illustrated.
The bottom of the probe assembly 36 includes a trolley plate 70,
which is threadedly engaged by the Y-axis drive screw 38 passing
through the aperture 72 defined within the trolley plate 70. The
screw rail end 74 is located directly above the aperture 72. A pair
of trolleys 76 are secured to the lower side of the trolley plate
70, and are structured to engage the rails 18, thereby permitting
the probe assembly 36 to slide along the rails 18. A pair of pillow
block assemblies 78 are disposed on either side of the trolley
plate 70, and define holes 80 therethrough, with the holes 80 being
structured to receive a guide shaft 82 on either side of the Y-axis
drive screw 38. This portion of the probe assembly 36 remains
adjacent to the rails 18, with the remainder of the probe assembly
36, described below, being structured for movement along the Y-axis
as controlled by the motor 58.
[0044] A shaft hangar 84 forms the lower portion of the movable
part of the probe assembly 36. Each end 86 of the shaft hangar 84
is structured to clamp around the guide shaft 82. A bracket 88 is
disposed above the shaft hangar 84 motor mounts 90, 92 extend
downward from the bracket 88 and upward from the shaft hangar 84,
respectively, and secure a Z-axis motor 94 therein. The Z-axis
motor 94 turns the pulley 96, Which is operatively connected to the
Z-drive arm 98 that is partially secured above the bracket 88. The
bracket 88 further defines a pair of upward extending end flanges
100, with a mount 102 centered thereon, and a plurality of roller
slides 104 between each side of the mount 102 and the corresponding
flange 100. An alignment plate 106 is pivotally mounted to each
side of the mount 102, and pivotally and slidably mounted across
the roller slides 104 on that side and the upward extending flange
100 of the bracket 88. Actuation of the Z-axis motor 94 thereby
causes the Z-drive arm 98 to move the mount 102 along the Z-axis,
with the roller slides 104 ensuring that the movement imparted by
the Z-axis motor 94 remains substantially along the Z-axis.
Movement of the mount 102 in the opposite direction is achieved by
spring pressure on the Z-drive arm 98.
[0045] A U-shaped bracket 108 is pivotally mounted on the mount
102, with the ends of the U-shape extending upward. The upper ends
of the U-shape define a pair of holes 110, structured to receive a
screw 112 passing through a thrust bearing 114 and ball bearing
116, into either side of a probe plate 118, thereby pivotally
securing the probe plate 118 within the bracket 108. A .THETA.-axis
motor 120 is secured to the back of the probe plate 118 by the
brackets 122 and clamps 124. The .THETA.-axis motor 120 is
operatively connected to the pulley 126, which is operatively
connected to the pulley 128 through the belt 130. The pulley 128 is
in turn connected to the worm gear shaft 132, mounted on the front
of the probe plate 118, via the bearing 134. The worm gear shaft
132 engages the worm gear 136, to which the sensor 138 has been
secured. The sensor 138 may be an ultrasound sensor, eddy current
sensor, or other non-destructive inspection sensor. The sensor 138
may thereby be rotated around the .THETA.-axis by the .THETA.-axis
motor 120 to change the angle at which a disc is inspected.
[0046] Referring to FIGS. 7-9, a low clearance head 140 is
illustrated. The low clearance head 140 is similar to the standard
head 10 in many respects. The low clearance head 140 includes the
base 142 structured for mounting on a presently available apparatus
for raising the inspection head between adjacent discs. A stand 144
extends upward from the base 142. The stand 144 includes a fixed
vertical rail 146 having a bracket 148 secured at its top end. A
pair of sliders 150 are slidably mounted on the rail 144, with an
arm 152 extending upward from each slider 150 to either side of a
top plate 154. A pair of arms 156 extends outward from the top
plate 154, and may include rollers 158 pivotally secured to their
ends. A second pair of arms 160 extends outward from the arms 156,
and include a pair of rollers 162 pivotally secured to their
ends.
[0047] A Y-base plate 164 may be disposed on top of the top plate
154. A pair of bolsters 166 are disposed atop either side of the
Y-base plate 164, with a thrust bearing 168 located between the top
bolsters, on top of the Y-base plate. A Y-axis drive screw 170
extends upward through the Y-base plate 164 and thrust bearing 168,
terminating at its lower end with the end cap 172. A pair of guide
rods 174 are disposed on either side of the Y-axis drive screw 170,
passing through the Y-base plate 164 and top bolsters 166. The
above described portion of the low clearance head 140 remains
stationary during movement in the Y-direction, while the following
portion will move along the Y-axis.
[0048] A Y-drive base 176 is disposed at the top end of the guide
rods 174 and Y-axis drive screw 170. A support block 178 may be
disposed below the Y-drive base, surrounding and providing
additional support for each of the guide rods 174. An endcap 180
surrounds and provides additional support for the Y-axis drive
screw 170. A Y-axis motor 182 is mounted on top of the Y-drive base
176, and may be secured there by the motor bracket 184. The Y-axis
motor 182 is operatively connected to the drive screw 170 through
the interaction of the miter gear 186, connected to the Y-axis
motor 182, and the miter gear 188, connected to the Y-axis drive
screw 170.
[0049] An X-axis motor 183 is mounted on a mounting plate 185, at
the top of the guide rods 174. A dovetail slide 187 is mounted on
the mounting plate 185, being operatively connected to the X-axis
motor 183 by the interaction of the miter gear 189, attached to the
motor 183, and the miter gear 191, attached to the leadscrew 193 of
the dovetail slide 187. The slider 195, threadedly connected to the
leadscrew 193, is connected to the Z-drive base 190.
[0050] A Z-drive base 190 is disposed above the Y-drive base 176,
and supports a Z-drive motor 192 thereon. The motor 192 is
operatively connected to a pulley 194. A slide mount plate 196 is
disposed above the Z-drive base 190 and Z-drive motor 192. The
slide mount plate 196 defines a pair of upwardly extending flanges
198 at each end. The head mount plate 104 is centered on the slide
mount plate 196, with a plurality of roller slides 202 located
between each side of the head mount plate 200 and the corresponding
upward flange 198. The roller slides 202 are all interconnected to
the directly adjacent roller slides 202, in a manner that permits
only linear sliding motions in a Z direction with respect to each
other. A Z-drive arm 204 is pivotally secured to the top surface of
the slide mount plate 196, and is operatively connected to the
pulley 194 and the head mount plate 200. Actuation of the Z-axis
motor 182 thereby moves the pulley 194, thereby causing the Z-drive
arm 204 to move the head mount plate 200 along the Z-axis, with the
roller slides 202 limiting the movement of the head mount plate 200
to within the Z-axis. A probe assembly 36, identical to the probe
assembly 36 described above, is mounted on top of the head mount
plate 200.
[0051] Referring to FIG. 10, an arc drive head 206 is illustrated.
The arc drive head 206 sits atop a base plate 208, which is similar
to the top plate 154, and which may be used to attach the arc drive
head 206 to a base 12 and stand 14, similar to those used for other
inspection heads. The base plate 208 has an X-axis motor 210
secured thereto by the motor bracket portions 212, 214. The motor
210 turns a drive screw 216 mounted between a pair of end blocks
218, 220. A slider 222 is threadably secured to the drive screw
216, and is rigidly attached to a slide base 224. A pair of curved
support arms 226, 228 extend upward from the slide base 224,
pivotally securing a probe frame 230 between their top ends. A
probe 232 is secured within the probe frame 230 by a plurality of
screws 234 passing through the back 236 of the probe frame 230, and
then threadably engaging the probe 232. Each of the screws 232 has
a spring disposed thereon, thereby biasing the probe 232 away from
the back 236 of the probe frame 230. Rotation of the probe frame
230 about the .PHI.-axis is controlled by the .PHI.-axis motor 240,
which is mounted on the probe support arm 226 by the motor bracket
242. The motor 240 is operatively connected to a worm gearshaft
244, extending upward therefrom, and which engages the worm gear
246 mounted on the side 248 of the probe housing 230.
[0052] Referring to FIGS. 11-12, a linear drive head 250 is
illustrated. The linear drive head 250 includes a base plate 252
that is similar to the base plate 208. An X-axis drive motor 254 is
secured to the base plate between the brackets 256, 258. The motor
254 is operatively connected to a drive screw 260 housed within a
slide 262, mounted on the base plate 252. A pulley 262 connected to
the motor 254 is connected by a belt to a pulley 264 connected to
the X-axis drive screw 260. A slide base 266 is threadably secured
to the X-axis drive screw 260, so that the movement of the slide
base 266 and the X-axis direction is controlled by the motor
254.
[0053] A pair of generally L-shaped arms 268 are secured to the
slide base 266, and a slider 276 is secured between the L-shaped
arms 268, with the bracket 278 therebetween. The bracket 278 is
biased away from the slide base 266 by the spring 270. A cable 272
secured at one end to a bracket 274 which is itself secured to the
bracket 278 may be used to pull the bracket 278 towards the slide
base 266. A Y-axis drive screw 280 is secured within the slider
276, and has a pulley 282 at one end. A Y-axis motor 284 is secured
to the top of the slider 276 by the bracket 286, and is operatively
connected to the pulley 288. A belt between the pulleys 282, 288
thereby permits the Y-axis motor 284 to control the Y-axis drive
screw 280. An outer probe frame 290 is threadably secured to the
Y-axis drive screw 280. An inner probe frame 292 is secured within
the outer probe frame 290 by a plurality of screws 294, each of
which has a spring 296 disposed thereon between the outer probe
frame 290 and inner probe frame 292, thereby biasing the inner
probe frame 292 away from the outer probe frame 290. A probe 298 is
housed within the inner probe frame 292. As with all other
inspection heads, on the probe 298 may be an ultrasonic inspection
probe, an eddy current inspection probe, or other non-destructive
inspection probe. A pair of rollers 300 are disposed near the top
of the linear drive head 250, and in the illustrated embodiment are
secured to the arm 302 secured to the bracket 286.
[0054] Referring to FIGS. 13-15, a probe insertion apparatus 304 is
illustrated. The probe insertion apparatus 304 includes a base 306
having a stationary telescoping member 308 extending upward
therefrom. A sliding telescoping member 310 fits around the
stationary telescoping member 308. Any of several inspection heads
may be secured to the top of the sliding telescoping member 310.
The sliding telescoping member may be caused to move up and down
with respect to the stationary telescoping member using any of
several means that are well known in the art, for example,
manually, through the use of hydraulic cylinders, through the use
of an electric motor driving an appropriate pulley and/or gear
system, etc. Because such systems are well known in the prior art,
they will not be described further herein. When an inspection is
desired, the sliding telescoping member may be raised with respect
to the stationary telescoping member from the position of FIG. 13
to the position of FIGS. 14-15, thereby locating the appropriate
inspection head between a pair of turbine discs 312, 314. The
inspection head may then be moved into engagement with the disc as
described above. In the case of the linear drive head of FIGS.
11-12, the spring 270 is allowed to bias the arms 268 to rotate the
inspection head 250 against the disc 316. In the case of the arc
drive head of FIGS. 10 and 16, the .THETA.-axis motor 240 will be
actuated to orient the probe 232 along the surface of the disc 318.
In the case of the low clearance head of FIG. 15, the inspection
head 140 will be moved along the X, Y, and Z-axes until it properly
engages the disc 318. Depending upon the inspection to be
performed, the disc may be rotated while the inspection head
remains stationary, or the disc may remain stationary while the
inspection head is moved along one of its axes of movements.
[0055] As another alternative, the standard head may be configured
to place two probes on the same side or opposite sides of the disc.
FIG. 1 illustrates a pair of inspection heads 36, each of which may
move independently of the other along the X, Z, and/or .THETA.
axis. As a further alternative, any head may be used in pairs, on
opposite sides of a disc, either for pitch-catch inspection or
merely to reduce the time required to perform an inspection as
shown by the pair of linear drive heads 250 in FIG. 17. Each linear
drive head 250 is supported by a stand 318 connected to a common
base 320, so that both heads 250 may be placed adjacent to opposite
sides of a disk simultaneously. In a pitch-catch inspection, which
is well-known in the art of nondestructive testing, one probe
transmits an ultrasonic signal that is received by the other
probe.
[0056] The present invention therefore provides an inspection head
capable of accurately and repeatably positioning a non-destructive
inspection probe against a component to be inspected. The
inspection head has independently and precisely controlled drive
systems for each axis of movement, and is constructed in a manner
that permits the inspection head to fit within relatively
inaccessible locations. The inspection head may be utilized with
either ultrasound, eddy current, or other non-destructive
inspection probes, may be utilized with individual or multiple
probes, and enables both straight and angled directional
inspections.
[0057] While specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular arrangements disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention which is to be given the full breadth of the appended
claims and any and all equivalents thereof.
* * * * *