U.S. patent application number 15/098596 was filed with the patent office on 2017-10-19 for cooling systems for heat-treated parts and methods of use.
The applicant listed for this patent is ALCOA INC.. Invention is credited to Richard Clay, Michael Friedman, David Hebert, Renee Sullivan.
Application Number | 20170298464 15/098596 |
Document ID | / |
Family ID | 60037944 |
Filed Date | 2017-10-19 |
United States Patent
Application |
20170298464 |
Kind Code |
A1 |
Hebert; David ; et
al. |
October 19, 2017 |
COOLING SYSTEMS FOR HEAT-TREATED PARTS AND METHODS OF USE
Abstract
Systems 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.
Inventors: |
Hebert; David; (Shrewsbury,
MA) ; Sullivan; Renee; (St. Simons Island, GA)
; Friedman; Michael; (Savannah, GA) ; Clay;
Richard; (Townsend, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALCOA INC. |
Pittsburg |
PA |
US |
|
|
Family ID: |
60037944 |
Appl. No.: |
15/098596 |
Filed: |
April 14, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C21D 1/667 20130101;
C21D 1/60 20130101; C21D 1/613 20130101 |
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; an upper
shroud assembly comprising at least one sub-assembly coupled to the
housing comprising an annular-shaped body, at least two annular
channels disposed within the annular shaped body, a cover attached
to the annular shaped body including at least two fluid inlets for
receiving a fluid source, and a plurality of atomization nozzles
annularly arranged on an outer surface of the annular shaped body
comprising outlets oriented to discharge atomized fluid at the
metallic part, wherein the at least two fluid inlets are in fluid
communication with the atomization nozzles via the at least two
annular channel; and a lower shroud assembly comprising at least
one sub-assembly coupled to the housing comprising an
annular-shaped body, at least two annular channels disposed within
the annular shaped body, a cover attached to the annular shaped
body including at least two fluid inlets, and a plurality of
atomization nozzles annularly arranged on an outer surface of the
annular shaped body comprising outlets oriented to cool the
metallic part, wherein the at least two fluid inlets are in fluid
communication with the atomization nozzles via the at least two
annular channels; wherein the at least two inlets in the upper and
lower shroud assemblies are in fluid communication with at least
one liquid source and at least one gas source such that each one of
the plurality of atomization nozzles are in fluid communication
with the at least one liquid source and the at least one gas source
produce an atomized fluid discharge when in use.
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 at least one subassembly of
the upper shroud comprises a first subassembly, wherein the outlets
of the plurality of atomization nozzles are oriented to discharge
the discharge atomized fluid along a y-axis; a second subassembly,
wherein the outlets of the plurality of atomization nozzles are
oriented to discharge the discharge atomized fluid along a z-axis;
and a third subassembly, wherein the outlets of the plurality of
atomization nozzles are oriented to discharge the atomized fluid
along an x-axis, wherein the y-, z-, and x-axes are relative to
ground, and wherein the annular shaped body of the first
subassembly has a smaller diameter than a diameter of the annular
shaped body of the second subassembly, and the second subassembly
diameter is smaller than a diameter of the annular shaped body of
the third subassembly; and wherein the at least one subassembly of
the lower shroud comprises a first subassembly, wherein the outlets
of the plurality of atomization nozzles are oriented to discharge
the discharge atomized fluid along a y-axis; and at least one
second subassembly, wherein the outlets of the plurality of
atomization nozzles are oriented to discharge the discharge
atomized fluid along a z-axis, wherein the y- and z-axes are
relative to ground, and wherein the annular shaped body of the
first subassembly has a smaller diameter than a diameter of the
annular shaped body of the second subassembly.
4. The system of claim 1, wherein the at least one subassembly of
the upper shroud comprises a first subassembly, wherein the outlets
of the plurality of atomization nozzles are oriented to discharge
the discharge atomized fluid along a y-axis; a second subassembly,
wherein the outlets of the plurality of atomization nozzles are
oriented to discharge the discharge atomized fluid a z-axis; and a
third subassembly, wherein the outlets of the plurality of
atomization nozzles are oriented to discharge the discharge
atomized fluid along an x-axis, wherein the y-, z-, and x-axes are
relative to ground, and wherein the annular shaped body of the
first subassembly has a smaller diameter than a diameter of the
annular shaped body of the second subassembly, and the second
subassembly diameter is smaller than a diameter of the annular
shaped body of the third subassembly.
5. The system of claim 1, wherein the at least one subassembly of
the lower shroud comprises a first subassembly, wherein the outlets
of the plurality of atomization nozzles are oriented to discharge
the discharge atomized fluid along a y-axis; and at least one
second subassembly, wherein the outlets of the plurality of
atomization nozzles are oriented to discharge the discharge
atomized fluid along a z-axis, wherein the y- and z-axes are
relative to ground, and wherein the annular shaped body of the
first subassembly has a smaller diameter than a diameter of the
annular shaped body of the second subassembly.
6. The system of claim 1, wherein the heat-treated metallic part is
axisymmetric.
7. The system of claim 1, wherein the at least one gas source is
air and the at least one liquid source is water.
8. The system of claim 7, wherein the plurality of atomization
nozzles are configured to provide atomization external to the
nozzle
9. The system of claim 7, wherein the plurality of atomization
nozzles are configured to provide atomization within the
nozzle.
10. The system of claim 7, wherein the plurality of atomization
nozzles are configured to provide atomization upstream of the
atomization nozzle.
11. The system of claim 7, 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.
12. The system of claim 7, wherein the water is pressurized in a
vessel by a gas and is in fluid communication with the atomization
nozzles.
13. The system of claim 1, wherein a selected one or both of the
upper and lower shroud assemblies are independently coupled to a
plate rotatable in a horizontal direction relative to ground during
operation, wherein the heat-treated part is stationary.
14. The system of claim 1, wherein the plurality of atomization
nozzles are configured to vertically oscillate relative to ground
during operation.
15. The system of claim 12, wherein the plurality of atomization
nozzles are further configured to vertically oscillate in the
vertical direction relative to ground.
16. The system of claim 1, wherein the at least one shroud assembly
is configured to be vertically adjustable relative to ground.
17. The system of claim 1, wherein the plurality of atomization
nozzles are radially disposed about the heat treated part at equal
distances.
18. The system of claim 1, wherein the plurality of atomization
nozzles are at a distance of about 1 to about 24 inches from the
heated-treated part during operation.
19. The system of claim 1, wherein the plurality of atomization
nozzles are configured to rapidly cool a thicker section of the
heat-treated part relative to a thinner section.
20. The system of claim 1, wherein the upper shroud assembly and/or
the lower shroud assembly are movably coupled to the housing.
Description
BACKGROUND
[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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
[0007] Disclosed herein are systems for the uniform cooling of a
heat-treated alloy part. In one embodiment, the system for cooling
a heat-treated metallic part includes a housing configured to hold
the heat-treated metallic part; an upper shroud assembly comprising
at least one sub-assembly coupled to the housing comprising an
annular-shaped body, at least two annular channels disposed within
the annular shaped body, a cover attached to the annular shaped
body including at least two fluid inlets for receiving a fluid
source, and a plurality of atomization nozzles annularly arranged
on an outer surface of the annular shaped body comprising outlets
oriented to discharge atomized fluid at the metallic part, wherein
the at least two fluid inlets are in fluid communication with the
atomization nozzles via the at least two annular channel; and a
lower shroud assembly comprising at least one sub-assembly coupled
to the housing comprising an annular-shaped body, at least two
annular channels disposed within the annular shaped body, a cover
attached to the annular shaped body including at least two fluid
inlets, and a plurality of atomization nozzles annularly arranged
on an outer surface of the annular shaped body comprising outlets
oriented to cool the metallic part, wherein the at least two fluid
inlets are in fluid communication with the atomization nozzles via
the at least two annular channels; wherein the at least two inlets
in the upper and lower shroud assemblies are in fluid communication
with at least one liquid source and at least one gas source such
that each one of the plurality of atomization nozzles are in fluid
communication with the at least one liquid source and the at least
one gas source produce an atomized fluid discharge when in use.
[0008] 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
[0009] Referring now to the figures wherein the like elements are
numbered alike:
[0010] FIG. ("FIG.") 1 schematically illustrates a turbine disk in
accordance with an embodiment of the present disclosure;
[0011] FIG. 2 schematically illustrates a downward perspective view
of a cooling system in accordance with the present disclosure,
wherein the cooling system utilizes upper and lower shroud
assemblies including arrays of atomization nozzles;
[0012] FIG. 3 schematically illustrates a sectional perspective
view of the upper and lower shroud assemblies of FIG. 2;
[0013] FIG. 4 illustrates a perspective bottom view of an annular
manifold assembly of the upper shroud assembly;
[0014] FIG. 5 illustrates a perspective top view of the annular
manifold assembly of the upper shroud assembly of FIG. 4; and
[0015] FIG. 6 illustrates a sectional view of the annular manifold
assembly of FIG. 5 taken along lines 6-6.
DETAILED DESCRIPTION
[0016] 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.
[0017] 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.
[0018] 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
having a complex geometry. 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.
[0019] 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 annular portion 12,
which forms the disk hub. A second portion 14 of the disk 10 exists
between the inner annular 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.
[0020] 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 to 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 annular 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.
[0021] Turning now to FIG. 2, there is depicted a downward
perspective view of an exemplary cooling system, generally
designated by reference numeral 100, in accordance with the present
disclosure for substantially uniformly cooling a heat-treated part
such as the turbine component 10 shown in FIG. 1. The illustrated
cooling system 100 includes a housing generally defined by
reference numeral 104 for supporting a shroud assembly generally
designated by reference numeral 101, wherein the shroud assembly
101 includes an upper shroud assembly 150 and a lower shroud
assembly 200 movably supported by the housing 104. The housing 104
is not limited to any particular shape and generally includes an
access opening for inserting and removing a heat-treated part to be
cooled with the cooling system 100. The illustrated housing 104
includes a plurality of horizontal 108 and vertical beams 110 to
support at least the upper shroud assembly 150 and optionally, the
lower shroud assembly 200. The housing 104 further includes upper
and lower support brackets 105, 107, respectively, attached to
stages 151, 201, respectively, wherein the brackets are movably
coupled to guide and actuation rods 106 attached to the housing 104
for vertical positioning of the upper and/or lower shroud assembly
during operation. In some embodiments, the guide and actuation rods
106 are coupled to an actuator to effect automated movement, e.g.,
a hydraulic telescopic rod or the like. The heated part, to be
cooled, e.g., turbine disc 10 shown in FIG. 1, would be seated
intermediate the upper and lower shroud assemblies 150, 200,
respectively.
[0022] As noted above, the guide and actuation rods 106 are coupled
to one or more of the horizontal and/or vertical beams 108 110 of
the housing 104 to vertically position the upper and/or lower
shroud assemblies 150, 200 within the housing 104 such that a
selected one or both can be selectively positioned about the part
to be treated as may be desired for different applications, e.g.,
the upper shroud assembly can be raised or lowered as desired. In
some embodiments, a selected one of the upper shroud assembly 150
or the lower shroud assembly 200 is fixedly coupled to the housing
104 and is not configured to move vertically.
[0023] As shown more clearly in FIG. 3, the upper shroud assembly
150 includes three manifold sub-assemblies 153, 154 and 156, which
are generally stackedly arranged. Manifold sub-assembly 153 is
positioned uppermost within the shroud assembly 150; manifold
sub-assembly 154 is positioned intermediate, and manifold assembly
146 is lowermost positioned in the stacked arrangement. The
manifold sub-assemblies 153, 154 and 156 collectively define an
annular dome shape for cooling the upper portion of the part to be
treated. With respect to manifold sub-assemblies 154 and 156, the
assemblies have diameters effective to accommodate the diameter of
a part to be cooled. In contrast, the uppermost manifold
sub-assembly 153 is configured to cool the interior regions of part
to be treated as will be discussed in greater detail below. Each of
the different manifold sub-assemblies 153, 154 and 156 in the upper
shroud assembly 150 is coupled to a plate 170, which can be
rotatably coupled to or integral to stage 151.
[0024] For ease in understanding as it relates to construction of
the upper shroud assembly 150, specific reference will now be made
in FIGS. 4-6 to the manifold sub-assembly 154. The manifold
sub-assemblies 153 and 156 will generally be constructed in a
similar manner based on the description of the upper annular
manifold assembly 154 albeit configured to cool different surfaces
of the complex geometric part to be treated. It should be apparent
based on the disclosure that more or less manifold sub-assemblies
could be included depending on the shape, size and complexity of
the part to cooled.
[0025] As shown more clearly in FIGS. 4-5, the upper annular
manifold assembly 154 includes a plurality of atomization nozzles
162 spacedly and concentrically arranged on an exterior surface of
an annularly shaped base 160 in one or more rows (two of which are
shown in FIG. 4, three of which are shown in FIG. 3) and a cover
164 including two fluid inlets 166, 168, wherein the cover 164 is
attached to the base 160. As shown more clearly in FIG. 6, the
fluid passageways from the inlets 166, 168 to the atomization
nozzles 162 are defined by at least two annularly shaped channels
156, 158 formed within the annularly shaped base 160. During
operation, at least one of the channels 156 or 158 is in fluid
communication with a gas and the other one of the other fluid
channels 156 or 158 is in fluid communication with a liquid,
wherein during cooling, the liquid and gas are pressurized and
mixed within the atomization nozzles 162 to provide an atomized
fluid.
[0026] The plurality of atomization nozzles 162 are generally
configured to be concentrically disposed about selected portions of
the part to be cooled, wherein each atomization nozzle 162 includes
an outlet oriented towards the part to be fluidly cooled. With
regard to manifold sub-assembly 154, the atomization nozzles 162
are configured to discharge cooling fluid towards a surface of the
part to be cooled in an angled direction along a z-axis. In
contrast, annular manifold sub-assembly 153 has the atomization
nozzles 172 therein (see FIG. 3) configured to discharge atomized
cooling fluid towards a top interior surface of the part to be
cooled such that the atomized fluid is discharged in a downward
direction substantially along a y-axis. Annular manifold
sub-assembly 156 includes atomization nozzles 182 (see FIG. 3)
configured to discharge atomized cooling fluid towards a side
surface of the part to be cooled substantially along an x-axis. It
should be apparent that the diameter of the opening in the annular
subassembly 156 is greater than the diameter of the part to be
cooled. The atomization nozzles 162, 172, and 182 for each
sub-assembly may be the same or different, and each can be
configured to provide a particular spray pattern, e.g., flat, fan,
round, or the like, depending on the particular atomization nozzle
employed.
[0027] Referring back to FIG. 3, the lower shroud assembly 200 is
generally configured to discharge atomized fluid upwards relative
to ground along the y and z-axes. The illustrated lower shroud
assembly 200 includes three annular sub-assemblies 210, 220, and
230, wherein the three annular sub-assemblies may be coupled
together. Again, it should be apparent based on the disclosure that
more or less manifold sub-assemblies could be included to define
the lower shroud assembly depending on the shape, size and
complexity of the part to cooled. Each of the sub-assemblies 210,
220, and 230 includes a plurality of atomization nozzles 212, 222,
and 232 configured to be concentrically disposed about selected
portions of a part to be cooled, wherein each atomization nozzle
includes outlets oriented towards the part to be fluidly cooled.
The atomization nozzles 162, 172, and 182 for each sub-assembly may
be the same or different, and each can be configured to provide a
particular spray pattern, e.g., flat, fan, round, or the like,
depending on the particular atomization nozzle employed. The
different manifold sub-assemblies 210, 220, 230 of the lower shroud
assembly 200 are each coupled to a plate 270, which can be
rotatably coupled to or integral to stage 201. Each manifold lower
manifold subassembly includes at least two annular fluid channels
similar to that of upper sub-assembly 154 described above.
[0028] The various atomization nozzles in the upper and lower
shroud assemblies 150, 200 are configured to atomize and project a
fine spray of droplets onto the heat-treated part to be cooled in a
pattern that provides uniform cooling of the heat treated part
regardless of thickness variation. 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 annular array at equal distances or in some embodiments, the
spacing between adjacent atomization nozzles may or may not be
equal.
[0029] In the depicted embodiments, the atomization nozzles
disposed in the upper and lower shroud assemblies 150, 200 are
generally configured to be spaced apart from the surfaces defining
the complex geometric part to be cooled at a distance from about 1
to about 24 inches, which may be oriented to spray an atomized
fluid onto the heat treated part at an angle that is not normal to
the surface. In other 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
within the upper and lower shroud assembly 150 or 200 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 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, a system 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 fluid inlets, e.g., 166,168 using a conduit (not
shown) or via a manifold (not shown).
[0030] 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.
[0031] A part holder (not shown) such as a cantilevered beam,
support surface, or the like can be employed in the housing 104 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
maximum 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.
[0032] Optionally, a selected one or both of the plates 170, 270
(see FIG. 3), upon which the upper and lower shroud assemblies 150,
200, respectively, are coupled thereto, are rotatably seated in the
stage 151, 201, respectively. In this manner, the one or more
shroud assemblies 150 and 200 including the arrays of atomization
nozzles in each respective subassembly can be configured to
oscillate or rotate in a horizontal plane while the heat-treated
part is stationary such as by an actuator, e.g., a hydraulic linear
actuator, motorized crank 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 not 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.
[0033] Optionally, the atomization nozzles can be configured to
vertically oscillate during the cooling process. In this optional
embodiment, the plurality of atomization nozzles can be selected to
vertically oscillate or alternatively, the shrouds 150 or 200 upon
which the atomization nozzles are disposed, can configured to move
in a horizontal 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.
[0034] In operation of the exemplary cooling system 100, a
heated-treated part 10 at an elevated temperature is removed from a
furnace and inserted into the cooling system. One or both shroud
assemblies 150, 200 are first vertically positioned to accommodate
insertion of the heat-treated part and repositioned such that the
upper and lower shroud assemblies 150 and 200 and arrays of
atomization nozzles thereon are concentrically disposed about the
heat-treated part. The heated part may be seated on a cantilevered
beam (not shown) or the like. 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.
[0035] 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.
[0036] 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.
[0037] 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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