U.S. patent application number 13/013188 was filed with the patent office on 2012-07-26 for automatic airfoil root prep machine and associated method.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Frank J. Trzcinski, Manfried Carl Verch, JR..
Application Number | 20120190272 13/013188 |
Document ID | / |
Family ID | 46544502 |
Filed Date | 2012-07-26 |
United States Patent
Application |
20120190272 |
Kind Code |
A1 |
Trzcinski; Frank J. ; et
al. |
July 26, 2012 |
AUTOMATIC AIRFOIL ROOT PREP MACHINE AND ASSOCIATED METHOD
Abstract
An apparatus for polishing an airfoil root includes a fixture
for holding the airfoil, an actuation cylinder assembly for moving
the fixture holding the airfoil, a brush, a motor for rotating the
brush, a switch, and control circuitry. The actuation cylinder
assembly is configured to move the fixture holding the airfoil
toward the brush to trigger the switch, and the control circuitry
is configured to run a timer when the switch is triggered to
control contact between the airfoil and the brush for
polishing.
Inventors: |
Trzcinski; Frank J.;
(Ellington, CT) ; Verch, JR.; Manfried Carl;
(Wallingford, CT) |
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
46544502 |
Appl. No.: |
13/013188 |
Filed: |
January 25, 2011 |
Current U.S.
Class: |
451/5 |
Current CPC
Class: |
B24B 27/033 20130101;
B24B 29/005 20130101; B24B 29/02 20130101; B24B 19/14 20130101 |
Class at
Publication: |
451/5 |
International
Class: |
B24B 51/00 20060101
B24B051/00 |
Claims
1. An apparatus for polishing an airfoil root, the apparatus
comprising: a fixture for holding the airfoil; an actuation
cylinder assembly for moving the fixture holding the airfoil; a
brush; a motor for rotating the brush; a switch, wherein the
actuation cylinder assembly is configured to move the fixture
holding the airfoil toward the brush to trigger the switch; and
control circuitry, wherein the control circuitry is configured to
run a timer when the switch is triggered to control contact between
the airfoil and the brush for polishing.
2. The apparatus of claim 1, wherein the actuation cylinder
assembly comprises a linear pneumatic cylinder.
3. The apparatus of claim 1 and further comprising: a limit switch
configured to detect excessive travel of the fixture indicative of
brush wear or the absence of the airfoil in the fixture.
4. The apparatus of claim 1 and further comprising: a hood for
shielding at least the brush during operation.
5. The apparatus of claim 4 and further comprising: a proximity
sensor for detecting whether the hood is open.
6. The apparatus of claim 1 and further comprising: a pair of
operator controls for activating the apparatus to perform a
polishing operation, wherein the pair of operator controls are
configured such that all must be triggered to activate the
apparatus to perform a polishing operation.
7. The apparatus of claim 1, wherein the actuation cylinder is
pressurized at approximately 96.53 kPa (14 psi) to advance the
fixture.
8. The apparatus of claim 1, wherein timer is configured to run to
a time period of approximately 1-2 seconds before the actuation
cylinder moves the fixture away from the brush, wherein the
actuation cylinder continues to advance the fixture toward the
brush during the time period of the timer.
9. The apparatus of claim 1 and further comprising: a vent system
for venting airborne material present during operation of the
apparatus.
10. The apparatus of claim 1 and further comprising: a mask for
masking a portion of the airfoil during polishing.
11. A method of polishing a workpiece, the method comprising:
positioning the workpiece in a fixture, wherein the fixture is
movable; rotating a brush; moving the fixture toward the rotating
brush at a given pressure in the actuation cylinder so that the
workpiece can contact the brush; triggering timer when a position
of the fixture reaches a given point relative to the rotating
brush; and moving the fixture away from the rotating brush with the
actuation cylinder after a time period of the timer has
elapsed.
12. The method of claim 11, wherein time period of the timer is
approximately 1-2 seconds.
13. The method of claim 11, wherein operation of the actuation
cylinder continues to advance the fixture toward the brush during
the time period of the timer.
14. The method of claim 13, wherein a pressure in the actuation
cylinder to move the fixture toward the rotating brush is
approximately 96.53 kPa (14 psi).
15. The method of claim 11, wherein the brush is rotated for at
least 2 minutes when activated to reduce motor cycling between
polishing operations.
16. The method of claim 11 and further comprising: detecting a
movement limit of the fixture relative to the rotating brush, to
detect excessive movement of the fixture.
Description
BACKGROUND
[0001] The present invention relates to an apparatus and method for
preparing airfoil roots through polishing or cleaning.
[0002] In many situations it is desirable to polish or otherwise
clean or prepare a workpiece. For example, in some applications,
portions of airfoils for gas turbine engines are desired to be
polished to remove oxidation to allow for electrical contact for a
plating operation. In such situations, it is desired to remove
oxidation to provide electrical contact at a bottom of a root of
the airfoil. The plating operation can then be performed, such as
for a Turbo Tip.TM. application where material is plated onto a tip
of the airfoil to facilitate cut-in seal formation at the airfoil
tip when installed in a gas turbine engine.
[0003] In the prior art, polishing operations were performed
manually with an operator manually holding a blade root in contact
with a rotating polishing brush. This manual process presents a
number of ergonomic and safety concerns because the operator must
perform repetitive tasks and place his or her hands near the
rotating brush. Moreover, manual polishing can result in
undesirable variation between polishing operations due to operator
actions that are not identical for all polishing operations.
[0004] Thus, an improved method an apparatus for workpiece
polishing or cleaning is desired.
SUMMARY
[0005] An apparatus for polishing an airfoil root according to the
present invention includes a fixture for holding the airfoil, an
actuation cylinder assembly for moving the fixture holding the
airfoil, a brush, a motor for rotating the brush, a switch, and
control circuitry. The actuation cylinder assembly is configured to
move the fixture holding the airfoil toward the brush to trigger
the switch, and the control circuitry is configured to run a timer
when the switch is triggered to control contact between the airfoil
and the brush for polishing. In another aspect, the present
invention includes an associated polishing method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a block diagram of an airfoil polishing machine
according to the present invention.
[0007] FIG. 2 is a perspective view of the machine of FIG. 1.
DETAILED DESCRIPTION
[0008] FIG. 1 is a block diagram of an airfoil polishing machine
10, and FIG. 2 is a perspective view of the machine 10. In the
illustrated embodiment, the machine 10 includes a brush 12, a motor
14, a fixture 16, an actuation cylinder 18, a switch 20, a control
valve 22, a limit switch 24, control circuitry 26, operator
controls 28, a hood 30, a proximity sensor 32 and a vent system 34.
A workpiece 36 and an optional workpiece mask 38 can be engaged
with the machine 10 for polishing, buffing, abrasive cleaning or
other preparation procedures. As used herein, the term "polishing"
is intended to encompass all polishing, buffing, abrasive cleaning
or other similar procedures.
[0009] The brush 12 can be an abrasive polishing brush, such as a
10 inch (25.4 cm) outer diameter aluminum oxide grit wheel brush,
available from Weiler Corp., Cresco, Pa. The particular
characteristics of the brush 12 can vary as desired for particular
applications. Moreover, in alternative embodiments, a polishing,
buffing or cleaning implement other than a brush could be used. The
motor 14 is used to rotate the brush 12. In one embodiment, the
motor is a 1 horsepower (746 watt) rotary buffer, available from
Baldor Electric Co., Fort Smith, Ark.
[0010] The fixture 16 is used to movably hold the workpiece 36. In
the illustrated embodiment, the fixture 16 includes a workpiece
holder slot 16-1 that can accept and retain the workpiece 36 (along
with the mask 38, if present) as well as a linear track 16-2 for
guiding the workpiece along a linear path that extends toward the
brush 12.
[0011] The actuation cylinder 18 can be a fluidically-actuated
cylinder that produces substantially linear actuation, such as a
pneumatic cylinder or a hydraulic cylinder. Fluid can be supplied
from a fluid supply 40 through a suitable control valve 22 to
pressurize the actuation cylinder 18 to induce movement. The fluid
supply 40 can be incorporated within the machine 10, or can be an
external supply such as a pneumatic shop air system connected to
the control valve 22 and the actuation cylinder 18 through suitable
conduits, hoses, pipes, etc. The fixture 16, specifically the
holder 16-1, is engaged with the actuation cylinder 18 such that
the actuation cylinder can move the fixture (carrying the workpiece
36) toward or away from the brush along the linear path.
[0012] The switch 20 is configured to sense when the fixture 16 has
moved the workpiece 36 to a given point sufficient to bring the
workpiece 36 into contact with the brush 12. When the switch 20 is
triggered, a timer is activated by the control circuitry 26 to
regulate the cleaning operation.
[0013] The limit switch 24 is configured to detect excessive
movement of the holder 16-1 of the fixture 16 toward the brush 12
beyond a given point. The limit switch 24 is generally located
closer to the brush 12 than the switch 20. Triggering (i.e.,
"faulting out") the switch 24 can indicate that the brush 12 is
worn or otherwise in need of replacement, or that a workpiece 36 is
not present in the fixture 16. Moreover, triggering the switch 24
can generate a suitable indication to an operator via the control
circuitry 26 that action is needed.
[0014] The control circuitry 26 acts as the central control for
most of the functions of the machine 10. The control circuitry 26
can include suitable circuits, processors, memory and other
subcomponents as necessary or desired for particular applications.
The operator controls 28 are provided to allow an operator to
activate and control the machine 10. In one embodiment, the
operator controls 28 include a pair of operator buttons, switches
or other suitable controls for activating the machine 10 to perform
a polishing operation, with the pair of operator controls
configured as "dead man" switches such that all (i.e., both) must
be triggered to activate the machine 10 to perform a polishing
operation. In this way the operator controls 28 help ensure that an
operator must place both hands at the controls 28 and away from the
brush 12 during polishing, to promote operator safety. The operator
controls can include other functionality, such as suitable
indicators or displays as desired.
[0015] The hood 30 can cover portions of the machine 10 during
operation for operator safety purposes and to help contain dust and
debris. The hood 30 can be pivotal, to allow access inside when
needed. When closed, the hood 30 can cover the brush 12, the motor
14, and at least portions of the fixture 16, the workpiece 36 and
the mask 38. The hood 30 can include an opening 30-1 to allow the
workpiece 36 to be inserted into the holder 16-1 of the fixture 16
with the hood 30 closed, and for the workpiece 36 and the fixture
16 to be moved toward the brush 12 during a polishing operation
while the hood 30 remains closed. The proximity sensor 32 can be
positioned adjacent to the hood 30 to detect when the hood 30 is
open. An open hood condition can be indicated to the control
circuitry 26, and can prevent a polishing operation from beginning,
that is, operations of the motor 14 and the actuation cylinder 18
can be prevented and actuation of the operator control 28
overridden. The vent system 34 can be operably connected to the
hood 30 to evacuate dust and debris.
[0016] The machine 10 can be used with a variety of types of
workpieces 36. In one embodiment, the workpiece 36 is an airfoil
for a gas turbine engine, and includes a root portion. The
workpiece 36 can be made of a nickel-based superalloy or other
materials. The machine 10 can be used to help remove oxidation from
the workpiece, in particular to remove oxidation from a bottom
portion of the root of an airfoil to allow for electrical contact
at the root for a later plating operation.
[0017] In order to perform a polishing operation, an operator can
first position the mask 38, if used, on the workpiece 36. The
workpiece 36 and the mask 38 are then placed in the holder 16-1 of
the fixture 16 (with the root facing toward the brush 12 if the
workpiece 36 is an airfoil), which is initially in a "home"
position spaced from the brush 12 and accessible from outside the
hood 30. The hood 30 is closed if it is open. The operator then
triggers the operator controls 28 to initiate polishing--the
operator should not be touching the workpiece 36 at this point. The
control circuitry 26 responds to the operator input by rotating the
brush 12 with the motor 14. The actuation cylinder 18 moves the
fixture 16 and the workpiece 36 toward the rotating brush 12 along
the linear path. The workpiece 36 (i.e., the root of the airfoil)
comes into contact with the rotating brush 12, which can abrasively
remove oxidation on the workpiece 36. The actuation cylinder 18
advances the fixture 16 holding the actuation cylinder 18 the
workpiece 36 toward the brush 12 at given pressure within the
actuation cylinder 18, such as approximately 14 psi (96.53 kPa).
The pressure within the actuation cylinder 18 can correspond to a
force of the brush 12 against the workpiece 36 of approximately 5-6
lbs (22.24-26.69 N) in some embodiments. When the actuation
cylinder 18 moves the fixture 16 far enough the trigger the switch
20, a timer is initiated by the control circuitry 26. The control
circuitry 26 governs operation of the actuation cylinder via the
control valve 22, and maintains contact between the workpiece 36
and the brush 12 for a given time period established by the timer,
such as 1-2 seconds in one embodiment. In this way, movement of the
holder 16-1 and the workpiece 36 toward the brush 12 is not to any
particular fixed spatial location, but can correspond to a variety
of spatial locations of the holder 16-1 and the workpiece 36
relative to the brush 12. The actuation cylinder 18 will continue
to advance the fixture 16 as long as pressure is supplied to do so,
with the corresponding travel distance of the workpiece 36 able to
vary depending upon factors such as the amount of wear of the brush
12. The limit switch 24 detects excessive movement of the fixture
16 which can indicate that the brush 12 is worn and in need of
replacement. After the given time period, during which polishing is
accomplished due to abrasive contact between the brush 12 and the
workpiece 36, the control circuitry 26 caused the actuation
cylinder 18 to move the fixture 16 and the workpiece 36 away from
the brush 12 and back to the home position. The operator can then
remove the polished workpiece 36, and can optionally insert a new
workpiece to begin another polishing operation. The control
circuitry 26 can let the motor 14 continue to run and rotate the
brush 12 after the fixture 16 has returned to the home position for
a period of time, such as two minutes, to reduce on/off cycling of
the motor 14 between successive polishing operations. Operation of
the motor 14 can be stopped during such a time period if the
proximity sensor 32 detects that the hood 30 has been opened.
[0018] Those of ordinary skill in the art will recognize that the
present invention provides numerous advantages and benefits. For
example, reliable and repeatable polishing can be provided despite
brush wear over time that can reduce the diameter of the brush or
variations in individual workpieces. Moreover, the need for complex
brush actuation equipment with complex positioning and sensors is
reduced, which results in greatly reduced capital costs for the
polishing equipment.
[0019] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *