U.S. patent application number 14/301693 was filed with the patent office on 2014-12-18 for cooling systems for heat-treated parts and methods of use.
The applicant listed for this patent is Firth Rixson Limited. Invention is credited to Richard Clay, Michael Friedman, David Hebert, Renee Sullivan, Mark Zurosky.
Application Number | 20140367898 14/301693 |
Document ID | / |
Family ID | 51162943 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140367898 |
Kind Code |
A1 |
Hebert; David ; et
al. |
December 18, 2014 |
COOLING SYSTEMS FOR HEAT-TREATED PARTS AND METHODS OF USE
Abstract
Systems and methods for cooling a heat-treated metallic part
include a plurality of atomization nozzles disposed on a stage and
radially disposed about the part to be cooled; and a fluid in fluid
communication with the atomization nozzles. The fluid may gas,
liquid, or a combination thereof, e.g., water and gas. During use,
the atomization nozzles are generally configured to rapidly cool
the thicker sections of the part relative to the thinner section
since the thicker sections are generally slower to cool. In some
embodiments, the stage can be configured to rotate about the part
during cooling. Methods are also disclosed. In one embodiment, the
method includes moving a plurality of outlets in a horizontal
direction while the heat-treated part is stationary while directing
an air and water mixture from the plurality of outlets onto the
heat-treated metallic part
Inventors: |
Hebert; David; (Shrewsbury,
MA) ; Friedman; Michael; (Savannah, GA) ;
Sullivan; Renee; (St. Simons Island, GA) ; Zurosky;
Mark; (Lexington, SC) ; Clay; Richard;
(Townsend, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Firth Rixson Limited |
East Hartford |
CT |
US |
|
|
Family ID: |
51162943 |
Appl. No.: |
14/301693 |
Filed: |
June 11, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61834094 |
Jun 12, 2013 |
|
|
|
Current U.S.
Class: |
266/44 ; 266/114;
266/251 |
Current CPC
Class: |
C21D 1/56 20130101; C21D
9/0068 20130101; C21D 1/667 20130101; C21D 9/0037 20130101; C21D
1/613 20130101; C21D 1/60 20130101; C21D 9/32 20130101; C21D 9/34
20130101; C21D 9/0025 20130101; C21D 1/62 20130101; C21D 9/40
20130101; C21D 2221/10 20130101; C21D 9/24 20130101 |
Class at
Publication: |
266/44 ; 266/114;
266/251 |
International
Class: |
C21D 1/667 20060101
C21D001/667; C21D 1/613 20060101 C21D001/613; C21D 1/60 20060101
C21D001/60 |
Claims
1. A system for cooling a heat-treated metallic part, comprising: a
housing configured to hold the heat-treated metallic part; at least
one shroud assembly comprising an array of atomization nozzles
configured to be concentrically disposed about the part during
operation of the system, each atomization nozzle comprising an
outlet; and a fluid source in fluid communication with the
plurality of atomization nozzles, wherein the outlet is oriented to
discharge atomized fluid at the heat-treated part.
2. The system of claim 1, wherein the heat-treated metallic part is
substantially circular in shape with radial cross-sections having
complex geometries and varying thickness across a diameter of the
part.
3. The system of claim 1, wherein the heat-treated metallic part is
axisymmetric.
4. The system of claim 1, wherein the fluid source comprises a gas
and a liquid.
5. The system of claim 4, wherein the fluid is configured to
provide atomization external to the nozzle
6. The system of claim 4, wherein the atomization nozzles are
configured to provide atomization within the nozzle.
7. The system of claim 4, wherein the atomization nozzles are
configured to provide atomization upstream of the atomization
nozzle.
8. The system of claim 4, wherein the gas is air and the liquid is
water.
9. The system of claim 8, wherein the air is at a pressure of
greater than 0 to 300 pounds per square inch (psi) and the water is
at a pressure of greater than 0 to 300 psi.
10. The system of claim 8, wherein the water is pressurized in a
vessel by a gas and is in fluid communication with the atomization
nozzles.
11. The system of claim 1, wherein the at least one shroud assembly
consists of an upper shroud assembly and a lower shroud
assembly.
12. The system of claim 1, wherein the at least one shroud assembly
is configured to be rotatable in a horizontal direction relative to
ground during operation, wherein the heat-treated part is
stationary.
13. The system of claim 1, wherein the atomization nozzles are
configured to vertically oscillate relative to ground during
operation.
14. The system of claim 12, wherein the atomization nozzles are
further configured to vertically oscillate in the vertical
direction relative to ground.
15. The system of claim 1, wherein the at least one shroud assembly
is configured to be vertically adjustable relative to ground.
16. The system of claim 1, wherein the atomization nozzles are
radially disposed about the heat treated part at equal
distances.
17. The system of claim 1, wherein the atomization nozzles are at a
distance of about 1 to about 24 inches from the heated-treated part
during operation.
18. The system of claim 1, wherein the arrays of atomization
nozzles are configured to rapidly cool a thicker section of the
heat-treated part relative to a thinner section.
19. A method of cooling a heat-treated metallic part, comprising:
inserting the heat-treated metallic part into a cooling system, the
cooling system comprising a housing configured to maintain the
heat-treated metallic part in a stationary position; at least one
shroud assembly comprising an array of atomization nozzles
configured to be concentrically disposed about the heat-treated
metallic part during operation of the system; forming an atomized
fluid from the atomization nozzle, the atomized fluid consisting
essentially of gas and water mixture, wherein the air is at a
pressure greater than 0 to 300 psi and the water is at a pressure
greater than 0 to 300 psi; and spraying the heat-treated metallic
part with the atomized fluid, wherein the atomized fluid consists
of atomized droplets.
20. The method of claim 19, wherein the gas is air.
21. The method of claim 19, further comprising oscillating the at
least one shroud assembly in a horizontal direction about the
stationary heat treated metallic part during operation.
22. The method of claim 19, wherein the at least one shroud
assembly consists of an upper shroud assembly and a lower shroud
assembly.
23. The method of claim 19, wherein spraying the heat-treated
metallic part with the atomized fluid is a substantially constant
cooling rate.
24. The method of claim 19, wherein spraying the heat-treated
metallic part with the atomized fluid is at a ramped cooling
rate.
25. A method of cooling a heat-treated metallic part, comprising:
positioning a plurality of outlets relative to the heat-treated
metallic part; and moving a plurality of outlets in a horizontal
direction while the heat-treated metallic part is stationary while
directing an air and water mixture from the plurality of outlets
onto the heat-treated metallic part.
26. The method of claim 25, wherein positioning the plurality of
outlets relative to the heat-treated metallic part comprises
concentrically positioning the plurality of outlets about the
heat-treated part at regularly spaced intervals.
27. The method of claim 25, wherein the air is at a pressure
greater than 0 to 300 psi and the water is at a pressure greater
than 0 to 300 psi.
28. The method of claim 25, wherein the plurality of outlets
comprise atomization nozzles.
29. A system for cooling a heat-treated metallic part, comprising:
a housing configured to hold the heat-treated metallic part in a
stationary position; at least one shroud assembly comprising an
array of atomization nozzles configured to be concentrically
disposed about the part during operation of the system and
configured to discharge a fluid at the heat-treated part, wherein
the at least one shroud assembly is configured to oscillate in a
horizontal direction about the stationary heat treated metallic
part; and a fluid source in fluid communication with the array of
atomization nozzles.
30. The system of claim 29, wherein the fluid source comprises air
and water.
31. (canceled)
31. (canceled)
32. The system of claim 29, wherein the atomization nozzles are
configured to articulate in a vertical direction during
operation.
33. The system of claim 29, wherein the at least one shroud
assembly is configured to move in a vertical direction.
34. The system of claim 30, wherein the air is at a pressure of
greater than 0 to 300 pounds per square inch (psi) and the water is
at a pressure of greater than 0 to 300 psi.
35. The system of claim 30, wherein the water is pressurized in a
vessel by a gas.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 61/834,094 entitled "Cooling Systems for
Heat-Treated Parts and Methods of Use" filed Jun. 12, 2013, which
is incorporated by reference.
BACKGROUND
[0002] The present disclosure generally relates to systems and
methods for cooling heat-treated parts, such as metallic work
pieces. More particularly, the present disclosure relates to
systems and methods for more controlled cooling heat-treated parts
of various geometries and thicknesses.
[0003] Certain metallic parts, also known as work pieces, are
subjected to severe environmental stresses during use. As an
example, certain components of jet aircraft turbines and turbines
for power generation, particularly the rotational components, are
subjected to extreme centrifugal forces and high thermal stresses
during use. Such components also have complex geometries,
oftentimes irregular shapes, wherein the thickness varies across
the metal component.
[0004] The metal parts, usually formed of nickel and titanium
superalloys, are commonly heat-treated to improve the strength and
wear characteristics of the part, so that they can better withstand
the rotational and thermal stresses experienced during use. The
heat-treating process usually begins in a furnace, wherein the
temperature is set precisely to control growth of specific
strengthening microstructures. The alloy properties such as
hardness, strength, toughness, ductility, elasticity, and the like
of the parts can be determined by the type of microstructure, grain
sizes, the heat-treatment temperature, the rate of cooling, the
composition of the cooling medium, and the like.
[0005] After the alloy part is heated and held above a critical
temperature for a predetermined duration, the alloy part must then
be cooled. A common method of cooling the heat-treated alloy parts
is by immersing the part in a fluid bath. This cooling process is
commonly referred to as "quenching." Quenching of alloy work pieces
is conventionally achieved by immersing the part in a liquid
coolant, such as water or oil. Immersion of the hot part in the
liquid coolant rapidly cools the part at a rate that is either
sufficient to maintain certain molecular characteristics of the
metal that were acquired in the heat-treatment process, or to
obtain certain different molecular characteristics that form during
the cooling (quenching) process.
[0006] For heat-treated parts having complex shapes and alloys that
are strain-rate sensitive, quenching through immersion in a liquid
coolant typically does not provide uniform cooling throughout the
part. Heat dissipates quickly from thin portions of the part, while
thicker portions retain heat for much longer periods. The
difference in cooling rates between the surface of the part and the
inner portions of the part can result in the creation of varying
material properties, varying grain structures, or, in extreme
cases, cracks in the work piece. Air quenching as opposed to liquid
immersion quenching has the advantage of producing a slower cooling
of the part than achieved with a liquid bath quench. However,
conventional air quenching methods have only a limited capability
in cooling work pieces, because it is difficult to control the air
quenching process aside from varying the length of time the heated
part remains in the cooling air stream. As such, current air
quenching processes are not as effective in providing uniform
cooling rates to parts having complex geometries and varying
thickness.
[0007] Thus, uniform cooling of work pieces having complex sizes
and shapes is, at best, extremely difficult using current
cooling/quenching techniques. As such, there is a need for systems
and methods that enable uniform cooling and formation of the
desirable metal grain structures in heat-treated parts having
complex shapes and sizes, particularly for the rotational parts
found in jet engines and turbine generators.
BRIEF SUMMARY
[0008] Disclosed herein are systems and methods for the uniform
cooling of a heat-treated alloy part. In one embodiment, a system
for cooling a heat-treated metallic part comprises a housing
configured to hold the heat-treated metallic part; at least one
shroud assembly comprising an array of atomization nozzles
configured to be concentrically disposed about the part during
operation of the system, each atomization nozzle comprising an
outlet; and a fluid source in fluid communication with the
plurality of atomization nozzles, wherein the outlet is oriented to
discharge atomized fluid at the heat-treated part.
[0009] In another embodiment, the system for cooling a heat-treated
metallic part, comprises a housing configured to hold the
heat-treated metallic part in a stationary position; at least one
shroud assembly comprising an array of atomization nozzles
configured to be concentrically disposed about the part during
operation of the system and configured to discharge a fluid at the
heat-treated part, wherein the at least one shroud assembly is
configured to oscillate in a horizontal direction about the
stationary heat treated metallic part; and a fluid source in fluid
communication with the array of atomization nozzles.
[0010] A method of cooling a heat-treated metallic part comprises
inserting the heat-treated metallic part into a cooling system, the
cooling system comprising a housing configured to maintain the
heat-treated metallic part in a stationary position; at least one
shroud assembly comprising an array of atomization nozzles
configured to be concentrically disposed about the heat-treated
metallic part during operation of the system; forming an atomized
fluid from the atomization nozzle, the atomized fluid consisting
essentially of gas and water mixture, wherein the air is at a
pressure greater than 0 to 300 psi and the water is at a pressure
greater than 0 to 300 psi; and spraying the heat-treated metallic
part with the atomized fluid, wherein the atomized fluid consists
of atomized droplets.
[0011] In another embodiment, the method comprises positioning a
plurality of outlets relative to the heat-treated metallic part;
and moving a plurality of outlets in a horizontal direction while
the heat-treated metallic part is stationary while directing an air
and water mixture from the plurality of outlets onto the
heat-treated metallic part.
[0012] The disclosure may be understood more readily by reference
to the following detailed description of the various features of
the disclosure and the examples included therein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0013] Referring now to the figures wherein the like elements are
numbered alike:
[0014] Figure ("FIG.") 1 schematically illustrates a turbine disk
in accordance with an embodiment of the present disclosure;
[0015] FIG. 2 schematically illustrates a perspective view of a
cooling system in accordance with the present disclosure, wherein
the cooling system utilizes opposing shroud assemblies including
arrays of atomization nozzles;
[0016] FIG. 3 schematically illustrates an enlarged perspective
view of a lower shroud in the cooling system of FIG. 2;
[0017] FIG. 4 illustrates an elevational view of a cooling system
in accordance with another embodiment of the present disclosure,
wherein the cooling system utilizes a single shroud assembly
including arrays of atomization nozzles;
[0018] FIGS. 5 and 6 illustrate perspective views of the cooling
system of FIG. 4 in the lowered and raised positions, respectively;
and
[0019] FIG. 7 graphically illustrates temperature as a function of
time for a part cooled by air only (i.e., convection only) and
cooled by an air-water mixture in accordance with the present
disclosure.
DETAILED DESCRIPTION
[0020] Disclosed herein are systems and methods for the rapid and
highly controlled cooling of a heat-treated metallic part. The
heat-treated metallic part to be cooled can be any metallic
material. In some embodiments, the heat-treated part is a high
temperature aerospace alloy. Typically, these materials must have
adequate performance characteristics for its intended use, such as
tensile strength, creep resistance, oxidation resistance, and
corrosion resistance, at high temperatures. More particularly, the
systems and methods are configured to maintain highly controlled
cooling across the surface of the metallic part being heat-treated
by tailoring the heat transfer coefficient in specific areas of the
part based on the cross-sectional thickness of the part in those
locations. The systems and methods disclosed herein can be
particularly advantageous in the production of jet engine and gas
turbine generator components, such as turbine disks, and the
like.
[0021] The production of metallic parts, such as turbine
components, generally begins with the shaping of a billet, e.g., an
alloy billet in the case of turbine components. The alloy billet is
forged into the desired shape under heat and pressure. In order for
the shaped part to have the desired microstructure and mechanical
properties, the shaped part is then heated and held at a
predetermined temperature for a predetermined duration. The part is
then cooled in a separate step, commonly referred to as quenching.
For most applications, uniform cooling of the heat-treated part is
desired because it will promote the development of a uniform grain
structure within the alloy composition and minimize distortion of
the piece. The cooling method described herein rapidly produces the
desired microstructure of the material and desired mechanical
properties while avoiding physical defects in the part, such as
cracking or distortion that may occur in other systems and
processes. Advantageously, the cooling process, also referred to
herein as a quenching process, provides a substantially uniform and
rapid reduction in temperature.
[0022] While the cooling systems and methods disclosed herein can
be useful for the rapid and controlled cooling of any heat-treated
part, the systems and methods are particularly useful for
heat-treated metallic parts intended to be used as components in
jet turbine engines and generators. The turbine components, such as
turbine disks and casings, are typically circular in shape with
radial cross-sections having complex geometries and/or varying
thickness across the diameter of the part. In one embodiment, the
turbine components are axisymmetric. As such, for ease in
discussion, further description of the cooling systems and methods
will be with respect to the controlled cooling of a turbine disk.
However, it is to be understood that the systems and methods
described herein are not limited to turbine disks, but are
applicable to any heat-treated part where controlled cooling is
highly desirable.
[0023] Referring to FIG. 1, a cross-sectional view of an exemplary
turbine component is a turbine disc 10 that is representative of a
heated treated part to be cooled. The illustrated cross-section of
the turbine disk 10 has a complex axisymmetric geometric shape,
rather than the simple rectangular shape that would be seen in the
cross-section of a plain flat disc. Thus, as used herein, the term
complex geometric shape is generally defined as a three dimensional
object having varying thicknesses. As shown, the turbine disk 10 is
radially symmetrical, i.e., axisymmetric having a radial
cross-section that is uniform about the entire circumference of the
part. The turbine disk 10 includes an inner portion 12, which forms
the disk hub. A second portion 14 of the disk 10 exists between the
inner portion 12 and the outer portion 16, which is located about
the circumference of the disk. The thickness of the second portion
14 is substantially greater than that of the inner and outer
portions 12, 16. The second portion 14 includes a fin or ridge 18
that protrudes outwardly from the main body of the turbine disk 10.
As seen from FIG. 1, the turbine disk 10 varies in thickness across
the radius of the disk, and in this embodiment generally comprises
about three distinct thicknesses. In other embodiments of a turbine
disk, the disk could include channels or grooves (not shown) cut
inwardly into the part, further altering the thickness profile of
the disk. These dissimilar portions will exhibit different cooling
rates due the differences in thickness. If the same amount of
cooling were applied to the entire disk, the thicker portions would
retain heat longer than their thinner counterparts. In other words,
the thicker portions, such as defined by the second portion 14 and
ridge 18 will retain heat for a longer period and thus take longer
to cool than the thinner portions, such as the inner portion 12 and
the outer portion 16. These thinner portions are capable of
dissipating heat more quickly than the thicker second portion 14
and ridge 18. The cooling systems and methods disclosed herein are
able to cool such turbine disks at a substantially more uniform
rate than that previously known, despite the disk's complex shape
and varying thickness profile. Moreover, relative to other systems
and processes, the cooling systems provides a significant reduction
in the cooling rate.
[0024] Turing now to FIGS. 2-3, there is depicted a cooling system,
generally designated by reference numeral 100, in accordance with
the present disclosure for substantially uniformly cooling a
heat-treated part 102 such as the turbine component shown in FIG.
1. The illustrated cooling system 100 includes a housing generally
defined by reference numeral 104 for supporting an upper shroud
assembly 140 via guide and actuation rods 106 or like supports. The
housing 104 is not limited to any particular shape and generally
includes an access for inserting and removing a heat-treated part
102 to be cooled with the cooling system 100. The illustrated
housing 104 includes a plurality of vertical 108 and horizontal
beams 110 to support at least the upper shroud 140.
[0025] The guide and actuation rods 106 are connected to the one or
more of the beams 108 and/or 110 of the housing 104 to vertically
position the upper shroud 140 relative to the housing 104 such that
the upper shroud assembly 140 can be selectively positioned about
the part 102 to be treated as may be desired for different
applications, i.e., the upper shroud can be raised and lowered as
desired.
[0026] In some embodiments, the housing 104 may further include a
stage 112 for supporting an optional lower shroud 120 via guide and
actuation rods 114. Optionally, instead of a stage 112, the guide
and actuation rods 114 supporting the lower shroud assembly 140 may
be coupled to one or more of the beams 108 and/or 110 of the
housing 104 or may be configured as a separate component. The guide
and actuation rods 114 effect vertical positioning of the lower
shroud 120 relative to the stationary housing 104. In this manner,
a selected one or both of the upper and lower shroud assemblies
120, 140, respectively, can be selectively positioned about the
part 102 to be cooled as well as be positioned to permit insertion
and removal of the part.
[0027] In some embodiments, the guide and actuation rods 106, 114
are coupled to an actuator to effect automated movement, e.g., a
hydraulic telescopic rod or the like. In some embodiments, a
selected one of the lower shroud assembly 120 or the upper shroud
assembly 140 is fixedly coupled to the housing 104 and is not
configured to move vertically.
[0028] A part holder (not shown) such as a cantilevered beam,
support surface, or the like can be employed to support the part
during cooling. The cantilevered beam or like support can be
fixedly attached to the housing or may be separate therefrom. The
part holder is generally configured to permit impact of an atomized
air-water mixture onto the heat-treated part to be cooled, the
mechanics of which be discussed in greater detail below.
[0029] As shown more clearly in FIG. 3, the upper and lower shroud
assemblies 120, 140, respectively, are each defined by one or more
discs 122 that are mounted on or to a table 124. The discs 122
generally include an aperture dimensioned to accommodate a spaced
apart relationship with at least a portion of the width of the
heat-treated part 102 to be cooled. In embodiments where there is
more than one disc, the discs are spaced apart in a stacked
arrangement via supports 116 and configured to be concentrically
disposed about at least a portion of a part to be cooled. Each disc
122 can have a different aperture to accommodate the diameter of
the part to be cooled, wherein the aperture of the disc closest to
the part generally has the largest diameter. A plurality of
atomization nozzles 126 are disposed on each disc 122 and are
collectively referred to as an array. The plurality of atomization
nozzles 126 comprise outlets oriented to fluidly cool the part to
be treated when the shroud assemblies are in the desired position.
The atomization nozzles 126 can be configured to atomize and
project a fine spray of droplets onto the heat-treated part to be
cooled. The droplet spray pattern can be configured to be
substantially repeatable. The number and spacing between adjacent
nozzles is not intended to be limited and may be optimized for the
intended application. For example, the atomization nozzles may be
axisymetrically disposed radially about the disc at equal distances
or in some embodiments, the spacing between adjacent atomization
nozzles may not be equal.
[0030] It should be apparent that atomization nozzles may be
supported by means other than a disc. For example, a ring of
serially attached atomization nozzles can be used. Alternatively,
the atomization nozzles may be disposed on a ring shaped fluid
conduit that is in fluid communication with the nozzles and a fluid
source.
[0031] In the depicted embodiments, the atomization nozzles 126
disposed on the discs 122 are generally configured to space the
atomization nozzles 126 from the part 102 at a distance from about
1 to about 24 inches, which may be oriented to spray a fluid onto
the heat treated part 102 at an angle that is not normal to the
surface. In some embodiments, some or all of the atomization
nozzles may spray at an angle that is normal to the surface of the
heat-treated part to be cooled. Each array of atomization nozzles
126 within the shroud assembly 120 or 140 can be in a circular
pattern that can be axisymmetric around the heat-treated part and
oriented to spray inwardly towards the heat-treated part to be
cooled. The atomization nozzles 126 are in fluid communication with
one or more fluid sources (not shown), which are not intended to be
limited. Generally, the fluid sources include at least one gas and
at least one liquid. A regulator (not shown) can be employed to
control fluid flow for each array. Using air and water as exemplary
fluid sources, the system 100 using the atomization nozzles can be
configured to selectively spray a fine mist of water in the form of
fine droplets upon the surfaces of the part to be treated, wherein
the water is gravity fed, lifted via a Venturi effect as is
generally well known in the art, or fed via pressurized
accumulators or a similar system to achieve required pressures. Air
pressures are controlled from greater than 0 to 300 pounds per
square inch (psi) and water pressure is controlled from greater
than 0 to 300 psi. The fluid can be externally mixed as a mixture
or within conduits (i.e., upstream of the nozzle) or internally
mixed within the atomization nozzle. In this manner, each part
surface that requires a different cooling rate can be sprayed with
a set of atomization nozzles whose fluid pressures, e.g., water and
air pressure, are tailored to achieve that surface's cooling rate
such that the cooling rates are substantially uniform for the
different thicknesses. The fluid pressures may be adjusted via the
regulator during cooling to adjust a surface's cooling rate as may
be desired to provide the intended metallurgical properties. The
fluid sources may be contained within vessels (not shown) fluidly
connected to the atomization nozzles 126 using a conduit (not
shown) or via a manifold (not shown).
[0032] Using fluid sources that include at least one gas and at
least one liquid is beneficial relative to gas-only or liquid-only
cooling. Gas only provides convective cooling that limits the
minimal spacing between nozzles to permit egress of the gas after
contact with the part surface. With regard to liquid-only quenching
systems, liquids are non-compressible and thus functions
hydraulically, which limits it practicality. By use of gas-liquid
atomization, more effective cooling has been realized in terms of
uniformity and efficiency. In one embodiment, an air and water
mixture is atomized within the atomization nozzles and sprayed onto
the part to be cooled. In one embodiment, the water (or liquid) is
fed to the atomization nozzles via a pump, compressed gas, or the
like. To minimize pulsing flow such as may occur with the use of
pumps that hydraulically deliver the liquid to the atomization
nozzles, the liquid can be pressurized using a gas, i.e., gas over
liquid delivery, to provide a more constant fluid flow to the
atomization nozzles.
[0033] Optionally, the table 124 (see FIG. 2) upon which the shroud
assemblies 120 or 140 are mounted include a rotatable stage 128
(shown more clearly in FIG. 3 with respect to shroud assembly 120;
shroud assembly 140 may be configured to be rotatable in a similar
manner). The stage 128 is configured to rotated within a stationary
annular ring 130. In this manner, the one or more shroud assemblies
120 and 140 including the arrays of atomization nozzles 126 can be
configured to oscillate or rotate in a horizontal plane while the
heat-treated part is stationary such as by a hydraulic linear
actuator 132, for example, as is partially shown in FIGS. 2-3 or a
motorized crank 232 as is generally shown in FIG. 5, or the like to
further increase cooling uniformity. That is, during cooling the
array of atomization nozzles horizontally rotates about the axis of
a stationary heat-treated part to be cooled. The actuator is note
intended to be limited and may be mechanical, hydraulic, pneumatic,
piezoelectric, electromechanical or any other actuation system
intended to oscillate and/or rotate the shroud assemblies relative
to the stationary part. It is advantageous to maintain the
heat-treated part in a stationary position as to make it less
likely for the part to fall and become damaged. Moreover, increased
cooling uniformity is provided especially in the situation where
one or more nozzles may have failed. The shrouds can independently
be configured to rotate or oscillate about its axis during the
cooling process. Again, it should be apparent that the rate of
oscillation may be unique for each forging.
[0034] Optionally, the atomization nozzles can be configured to
move vertically during the cooling process. In this optional
embodiment, the plurality of atomization nozzles can be selected to
articulate or alternatively, the shrouds 120 or 140 upon which the
atomization nozzles are disposed, can configured to move in a
vertical direction during the cooling process. Thus, oscillation
relative to a stationary heat treated part to be cooled can be
effected in the horizontal direction, the vertical direction, or
both the horizontal and vertical directions as may be desired for
some applications.
[0035] Turning now to FIG. 4, there is shown a cooling system 200
configured with a single shroud assembly 220 connected to a housing
204. The shroud assembly 220 is similar in construction and
function to shroud assemblies 120, 140 as previously discussed. The
shroud assembly 220 includes one or more spaced apart discs 222 (or
the like), each having thereon an array of atomization nozzles 226.
The shroud assembly 220 is generally disposed above a heat-treated
part 202 to be cooled and is configured to be selectively raised or
lowered via guide and actuation rods 206. However, it should be
apparent that the shroud assembly 220, if desired, can be generally
disposed below the heat treated part 202 and raised or lowered via
guide and actuation rods 206. The heat-treated part is seated on a
support 203 such as a stage, cantilevered beam, or the like.
Optionally, the one or more spaced apart discs 222 can be disposed
onto a rotatable stage as previously described using a motorized
crank system 232 or other rotary actuator to effect rotation or
oscillation about a horizontal plane during use while the part to
be cooled is stationary. FIGS. 5 and 6 depict the shroud assembly
of the cooling system in the lowered and raised position,
respectively.
[0036] In operation of the exemplary cooling system 100, a
heated-treated part 102 at an elevated temperature is removed from
a furnace and inserted into the cooling system. One or both shroud
assemblies 120, 140 are first vertically positioned to accommodate
insertion of the heat-treated part and repositioned such that the
shroud assemblies 120 and 140 and arrays of atomization nozzles 226
are concentrically disposed about the heat-treated part. A fluid
mixture of gas and liquid, e.g., air and water, is then fed to the
atomization nozzles, wherein the pressures of the air and water are
effective to atomize the water so as to provide fine droplets to
about the surface of the heat-treated part, thereby, in the case of
an air/water mixture, generating mist. The liquid component of the
atomization fluid can be the primary coolant for the cooling
system. The spray is continued until a desired temperature is
reached, e.g., ambient temperature. In some embodiments, the
temperatures of the air and/or water can vary prior to discharge
from the atomization nozzles.
[0037] The period of time required to cool the forging (i.e.,
heat-treated part) will generally depend upon the cross-sectional
area of the forging. The cooling rate may be constant throughout
the cooling process or ramped by adjusting the fluid pressures to
the nozzles and/or by selection of the atomization nozzles.
[0038] FIG. 7 graphically illustrates a comparison of the cooling
process in accordance with the present disclosure relative to an
air-only cooling process. In this process, a sample block was
heated two times and subsequently cooled by the cooling process in
accordance with the present disclosure and the air-only cooling
process. As shown, the cooling process was generally non-linear
compared to the air-only process and provided a marked reduction in
cooling time. Upon additional analysis, it was observed that the
mist cooling curve reduced the thermal shock at the onset of the
cooling process. Thus, the chances of cracking the part were
reduced.
[0039] The terms "first," "second," and the like, herein do not
denote any order, quantity, or importance, but rather are used to
distinguish one element from another. The terms "a" and "an" herein
do not denote a limitation of quantity, but rather denote the
presence of at least one of the referenced item.
[0040] While the invention has been described with reference to
various exemplary embodiments, 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 disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
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