U.S. patent application number 12/056359 was filed with the patent office on 2008-10-02 for vertical heat treatment system.
Invention is credited to Paul M. Crafton, Scott P. Crafton, Ian French, Volker Knobloch.
Application Number | 20080236779 12/056359 |
Document ID | / |
Family ID | 39615661 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080236779 |
Kind Code |
A1 |
Crafton; Scott P. ; et
al. |
October 2, 2008 |
VERTICAL HEAT TREATMENT SYSTEM
Abstract
A system and method for forming and heat treating metal castings
is provided with a vertical heat treatment unit positioned adjacent
and downstream from a pouring station at which a series of molds
are filled with a molten metal to form the castings. The vertical
heat treatment unit includes a vertically oriented furnace chamber
in which the castings are received, and which has a reduced
footprint to reduce the manufacturing floor space required for the
vertical heat treatment unit, and to enable the vertical heat
treatment unit to be positioned in close proximity to the pouring
station.
Inventors: |
Crafton; Scott P.;
(Marietta, GA) ; Crafton; Paul M.; (Kennesaw,
GA) ; French; Ian; (Berlin, NJ) ; Knobloch;
Volker; (Woodstock, GA) |
Correspondence
Address: |
WOMBLE CARLYLE SANDRIDGE & RICE, PLLC
ATTN: PATENT DOCKETING 32ND FLOOR, P.O. BOX 7037
ATLANTA
GA
30357-0037
US
|
Family ID: |
39615661 |
Appl. No.: |
12/056359 |
Filed: |
March 27, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60908743 |
Mar 29, 2007 |
|
|
|
60909048 |
Mar 30, 2007 |
|
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|
Current U.S.
Class: |
164/76.1 ;
164/270.1 |
Current CPC
Class: |
C21D 9/005 20130101;
F27B 9/16 20130101; B22D 45/00 20130101; B22D 47/00 20130101; C21D
9/0006 20130101; B22D 47/02 20130101; F27B 9/243 20130101 |
Class at
Publication: |
164/76.1 ;
164/270.1 |
International
Class: |
B22D 45/00 20060101
B22D045/00; B22D 19/00 20060101 B22D019/00 |
Claims
1. A system for forming and heat treating metal castings, the
system comprising: a pouring station for pouring a molten metal
into a mold to form the castings; and a vertical heat treatment
unit positioned downstream from said pouring station; wherein said
vertical heat treatment unit comprises: a furnace oriented in a
substantially vertically extending alignment so as to enable a
reduction in area occupied by said vertical heat treatment unit,
and defining an upstanding a furnace chamber in which the castings
are received; and a series of heat sources positioned along said
furnace chamber for applying heated fluid flows into said furnace
chamber for conveying the castings to said vertical heat treatment
unit.
2. The system of claim 1 and further comprising a transport
mechanism moveable between said pouring station to said vertical
heat treatment unit for conveying the castings to said vertical
heat treatment unit.
3. The system of claim 1 and wherein said vertical heat treatment
unit further comprises a vertically moveable conveyor positioned
within said furnace chamber for moving the castings along a
vertically extending heat treatment path through said furnace.
4. The system of claim 1 and wherein said furnace chamber of said
vertical heat treatment unit further comprises a series of
compartments arranged in stacked series along said furnace chamber,
and in which the castings are loaded for heat treatment, and
wherein said heat sources are arranged along floor and ceiling
portions of said compartments.
5. The system of claim 4 and further comprising a loader mounted
within said furnace chamber and adapted to move the castings into
and out of said compartments.
6. The system of claim 4 and wherein each compartment includes an
outer door and wherein said vertical heat treatment unit further
comprises an externally mounted loader for loading castings into
and removing the castings from each of said compartments.
7. The system of claim 1 and further comprising a conveyor
extending along a path of travel between said pouring station and
said vertical heat treatment unit, and at least one heat source
positioned along said path of travel for applying heat to the
castings as they are transitioned from said pouring station to said
vertical heat treatment unit.
8. The system of claim 1 and wherein said heat sources comprise
conduction heaters, convection heaters, radiant heaters, infrared
heaters, or fuel fired blowers.
9. The system of claim 1 and wherein said heat sources comprise a
plurality of nozzles arranged about said furnace chamber for
applying a heated fluid media to the castings for heat treatment of
the castings.
10. The system of claim 9 and wherein said nozzles are located
approximately 5-7 inches from a centerline of the castings passing
through said furnace chamber.
11. The system of claim 9 and wherein at least one of said nozzles
comprises a slotted nozzle having a slotted opening extending
substantially along its length.
12. The system of claim 9 and wherein at least one of said nozzles
comprises a plenum having series nozzle openings spaced
therealong.
13. A system for forming castings, comprising: at least one pouring
station in which a molten metal material is introduced into a
series of molds; a plurality of heat treatment cells mounted
downstream and in proximity to said at least one pouring station;
wherein said heat treatment cells each comprise a vertically
oriented furnace having a reduced footprint to enable said heat
treatment cells to be positioned proximate to said at least one
pouring station, a plurality of heat sources applying high velocity
heated fluid flows to the castings, and a means for retaining the
castings within said furnace and in a position to optimize
application of the high velocity heated fluid flows to the
castings; a transport system extending along a path adjacent said
at least one pouring station and at least one of said heat
treatment cells for moving the castings from the pouring station to
at least one of said heat treatment cells during which the castings
are permitted to solidify.
14. The system of claim 13 and wherein said heat sources comprise a
series of nozzles applying high velocity fluid flows directed at
the castings, wherein said nozzles are positioned at a distance
from an approximate center-line of the castings of about 5-7 times
a diameter or width of an opening of the nozzles.
15. The system of claim 13 and wherein at least one of said nozzles
comprises a slotted nozzle having a slotted opening extending
substantially along its length.
16. The system of claim 13 and wherein at least one of said nozzles
comprises a plenum having series nozzle openings spaced
therealong.
17. The system of claim 13 and wherein said vertical heat treatment
unit further comprises a vertically moveable conveyor positioned
within said furnace chamber for moving the castings along a
vertically extending heat treatment path through said furnace.
18. The system of claim 13 and wherein each furnace of each of said
heat treatment cells comprises a series of compartments in which at
least one casting is received and retained for heat treatment, and
wherein said heat sources comprise nozzles arranged along upper and
lower portions of said compartments for applying the heated fluid
flows to the castings along a desired portions thereof.
19. The system of claim 13 and wherein said heat sources comprise
nozzles each having ports located a predetermined distance from a
centerline of a casting to which said nozzles are applying the
heated fluid, based upon a size of said nozzle ports, and applying
the heated fluid at a flow velocity of approximately 4,000-40,000
feet per minute.
20. A method of forming and treating castings, comprising: pouring
a molten metal into a series of molds to form the castings;
removing and transferring the molds to a cell unit located
proximate to the pouring station for heat treatment; as the molds
are transferred to the cell unit, allowing the molten metal to
substantially solidify sufficiently to form the castings;
introducing the castings into the cell unit and subjecting the
castings to a high temperature, high velocity fluid media flow;
wherein subjecting the castings to a high temperature, high
velocity fluid media flow comprises locating a series of nozzles
having one or more nozzle openings at a distance from an
approximate center-line of the castings being treated by the series
of nozzles of approximately 5-7 times the size of the nozzle
openings; and retaining the castings within the cell unit for a
time sufficient to heat treat the castings to achieve desired
physical properties of the castings.
21. The method of claim 20 and wherein subjecting the castings to a
high temperature, high velocity fluid media flow further comprises
applying a heated air flow from the nozzles at a velocity of
approximately 4000-40,000 feet per minute.
22. The method of claim 20 and wherein introducing the castings to
the cell unit comprises engaging the castings with a loader and
loading the castings into selected compartments within the cell
unit.
23. The method of claim 22 and wherein the nozzles are positioned
along at least upper and lower portions of each of the compartments
for applying the high temperature, high velocity fluid media flows
to the castings as the castings are retained in their
compartments.
24. The method of claim 22 and wherein the nozzles are mounted
along the periphery of the cell unit, and introduce a high
temperature, high velocity, turbulent air flow through a furnace
chamber of the cell unit, and further comprising conveying the
castings through the furnace chamber along a path of movement timed
to minimize heat loss from the castings therein.
25. The method of claim 24 and wherein conveying the castings
through the furnace chamber comprises loading the castings on a
carousel and moving the carousel in a stepped motion in forward and
reverse directions to provide a desired separation between incoming
castings and castings nearing completion of a heat treatment
cycle.
26. The method of claim 20 and further comprising maintaining the
casting at or above a process control temperature for the metal
thereof as the castings are transferred from the pouring station to
the cell unit.
27. The method of claim 20 and further comprising oscillating the
nozzles and/or the castings as the high temperature, high velocity
fluid media flow is applied to the castings from the nozzles.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application claims the benefit of the
filing date of U.S. provisional patent application No. 60/908,743,
filed Mar. 29, 2007 and U.S. provisional patent application No.
60/909,048, filed Mar. 30, 2007, according to the statutes and
rules governing provisional patent applications, particularly USC
.sctn.119(e)(1) and 37 CFR .sctn.1.78(a)(4) and (a)(5). The
specification and drawings of the provisional patent application
are specifically incorporated fully herein by reference.
BACKGROUND OF THE INVENTION
[0002] Traditionally, in conventional processes for forming metal
castings, a mold, such as a metal die or sand mold having an
interior chamber with the exterior features of a desired casting
defined therein, is filled with a molten metal. A sand core that
defines interior features of the castings is received and/or
positioned within the mold to form the interior detail of the
casting as the molten metal solidifies about the core. After the
molten metal of the castings has solidified, the castings generally
are moved to a treatment furnace(s) for heat treatment of the
castings, removal of sand from the sand cores and/or molds, and
other processing as required. The heat treatment processes
condition the metal or metal alloys of the castings to achieve the
desired physical characteristics for a given application.
[0003] FIG. 1A illustrates one type of a conventional heat
treatment apparatus in which a series of castings can be placed
within a basket and passed along a roller health or similar
conveying mechanism through one or more heating chambers of the
heat treatment apparatus. As the castings are passed through the
chambers of the heat treatment apparatus, the castings are heated
to a solution heat treatment temperature. Additionally, as the
castings move along the chambers of the heat treating furnace, the
sand cores or molds of the castings also can be broken down as
their binder materials are combusted, such that the castings can be
de-cored and their molds broken down and removed, with the sand
falling beneath the roller hearth for collection. After the
castings have been heat treated, they can be removed from the heat
treatment unit or furnace and directed to a quench station or
tank.
[0004] During the transfer of the castings from the pouring station
to the heat treatment station, and especially if the castings are
allowed to sit for any appreciable amount of time, however, the
castings may be exposed to the ambient environment of the foundry
or metal processing facility. As a result, the castings tend to
rapidly cool down from a molten or semi-molten temperature. While
some cooling of the castings is necessary to allow the castings to
solidify, the more the temperature of the castings drops, and the
longer the castings remain below a process critical temperature
(also referred to herein as the "process control temperature") of
the castings, the more time is required to heat the castings up to
a desired heat treatment temperature and to heat treat the
castings. For example, as illustrated in FIG. 1B, it has been found
that for certain types of metals, for every minute of time that the
castings drops below its process control temperature, at least
about four minutes or more of extra heat treatment time will be
required to achieve the desired solution heat treatment results in
the castings. Thus, even dropping below the process control
temperature for the metal of the castings for as few as 10 minutes
may require at least about 40 minutes of additional heat treatment
time to achieve the desired physical properties. As a consequence,
therefore, castings typically are heat treated for 2 to 6 hours, in
some cases longer, to ensure the desired heat treatment effects are
achieved in all the castings of a batch or series. This results in
greater utilization of energy and, therefore, greater heat
treatment costs.
[0005] Accordingly, it can be seen that a need exists for a system
and method of heat treating castings that addresses the foregoing
and other related and unrelated problems in the art.
SUMMARY OF THE INVENTION
[0006] Briefly described, the present invention generally comprises
a system for enabling the pouring, forming, heat treating, and
further processing of castings formed from metal and/or metal
alloys at enhanced rates and efficiency. The castings are formed at
a pouring station at which a molten metal such as aluminum, iron,
or a metal alloy, is poured into a mold or die, such as a permanent
metal mold, semi permanent mold, or a sand mold. The molds then are
moved from the pouring or casting position to a transfer position,
where the castings can be removed from their molds or transferred
directly to a vertical heat treatment unit according to the present
invention. The transfer mechanism typically includes a robotic arm,
crane, overhead hoist or lift, pusher, conveyor, or similar
conveying mechanism. The same mechanism also may be used to remove
the castings from their molds and to transfer the castings to the
vertical heat treatment unit(s). During this transition from the
pouring station to the vertical heat treatment unit(s), the molten
metal of the castings generally is permitted to cool to an extent
sufficient to form the castings, while generally being monitored
and heat applied thereto as needed to maintain the castings at or
above a process control temperature for the metal thereof.
[0007] The vertical heat treatment unit according to the present
invention comprises a vertically aligned heat treatment or "cell
unit" having a reduced footprint such that it typically can be
arranged adjacent or in close proximity to a loading carousel for
one or more pouring stations, which carousels can be positioned
adjacent their associated pouring stations. The castings also can
he received on a transfer line or monorail from their pouring
stations and then transferred directly to a vertical heat treatment
unit or to a loading carrousel for each vertical heat treatment
unit. Each vertical heat treatment unit or cell unit generally can
include a vertically extending furnace chamber having heat sources,
such as blowers, fans, radiant heaters, infrared, inductive,
convection, conductive, or other types of heating elements. The
ceiling and walls of the furnace chamber further generally will
include a radiant material that radiates or directs heat toward the
castings and/or molds with the castings therein, as they are moved
through the furnace chamber. The castings are received and
maintained within their cell unit or vertical heat treatment system
for a time and at temperatures sufficient to heat treat the
castings as needed to achieve desired mechanical properties
thereof.
[0008] The heat sources further can include a variety of heating
systems including conduction, convection, and other sources. In one
embodiment, the heat sources can comprise high velocity forced air
heating sources that direct turbulent, high velocity flows of
heated air or other fluid media at velocities flows of
approximately 2,500-4,000, up to approximately 40,000 feet per
minute generally at distances of about 21-26 inches or less, and as
short as 2-10 inches, from the castings. The velocity of the heated
air flows and the distance of the applicator nozzles from the
castings and their molds generally can be determined based upon the
diameter and the configuration(s) of the nozzles being used (i.e.,
use of a series of spaced large, medium, or small diameter circular
nozzles, slotted nozzles, or other configurations) and the
positions/locations of the nozzles with respect to the centerlines
of the castings as they are conveyed through the furnace chamber of
the vertical heat treatment unit, which can be adjusted depending
on sizes of the castings and the volume and velocity of the flames.
The air flows further generally are at temperatures sufficient to
promote heat treatment of the castings and additionally can assist
with mold breakdown and core removal as the castings are moved
through their vertical heat treatment units.
[0009] The vertical heat treatment unit further can include a
conveying mechanism such as a rotary carousel that extends upwardly
through the furnace chamber and includes a series of platforms,
trays or racks on which a series of castings, i.e., 1-4 or more
castings, are received. The castings typically will remain within
in their molds, although they also can be previously removed from
their molds prior to introduction into the vertical heat treatment
unit. The castings generally will be fed into the furnace chamber
by a manipulator, which can include a crane, forklift, or similar
mechanism or can comprise the transfer robot of an associated
loading carousel. As the castings are fed into the furnace chamber,
the rotary carousel generally is operated in a up and down stepping
motion, for example moving up one step to receive the castings and
then downwardly two steps so as to ensure that a desired separation
between incoming (colder) castings and outgoing (fully heated)
castings is as large as possible. The vertical heat treatment unit
can further include features that assist in removal and reclamation
of the sand from the molds of the castings, which generally will be
collected and reclaimed for reuse.
[0010] Alternatively, the castings can be received within the
vertical heat treatment unit on a gantry or elevator type conveying
mechanism and placed within one or more compartments or chambers of
a grid unit for heat treatment. Each of the compartments are
insulated along their side walls as to prevent heat transfer
between castings through the side walls, while the floors and
ceilings thereof can have slots or openings to enable sand removed
from the sand cores and/or molds of the castings to pass
therethrough for collection at the bottom of the vertical heat
treatment unit. In another alternative embodiment, the vertical
heat treatment unit can include a series of conveyors in a
vertically stacked arrangement with heat sources such as high
velocity fluid media nozzles mounted therealong for directing
heated fluid flows toward the castings.
[0011] The vertical heat treatment unit of the present invention
thus provides a significantly smaller footprint within the casting
facility, which enables the vertical heat treatment unit to be
placed in as close proximity as possible to the pouring stations.
The vertical heat treatment unit of the present invention
additionally can utilize existing robotic transfer mechanisms,
lifts, or cranes for receiving the castings substantially directly
from the pouring stations or from a loading carousel, with the time
that the castings are exposed to the ambient environment of the
metal processing facility thus being substantially minimized. As a
result, the castings can be maintained at or above their process
control temperature, as they are transferred from the pouring
station to the vertical heat treatment unit of the present
invention. In addition, the castings further can be monitored as
they are removed from their pouring stations and transfered to
their vertical heat treatment units, and additional heat added,
such as by additional heating sources such as infrared lamps,
heated fluid flows, inductive heaters, and/or other heat sources,
as needed to substantially arrest cooling and/or maintain the
temperature of the castings substantially at or above the process
control temperature for the metal of the castings. Accordingly, the
time required to heat treat the castings can be significantly
reduced from approximately 2-6 hours down to as low as about 40
minutes to an hour.
[0012] Various objects, features and advantages of the present
invention will become apparent to those skilled in the art upon
review of the following detailed description when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A is a schematic illustration of an exemplary
conventional heat treatment unit.
[0014] FIG. 1B is a graphical representation of a heat treatment
cycle, illustrating the increase in heat treatment time required
for each minute of time the temperature of the casting is below its
process control temperature.
[0015] FIG. 2A is a schematic illustration of an exemplary metal
casting processing system according to various aspects of the
present invention.
[0016] FIG. 2B is a schematic illustration of another exemplary
metal casting processing system illustrating the collection and
transfer of castings from multiple pouring stations to vertical
heat treatment units according to various aspects of the present
invention.
[0017] FIG. 3 is a perspective view of a casting and mold.
[0018] FIG. 4 is a perspective illustration of the vertical heat
treatment according to one embodiment of the vertical heat
treatment unit of the present invention.
[0019] FIGS. 5A and 5B are perspective views of the vertical heat
treatment unit of FIG. 4, with parts broken away to illustrate the
internal portions of the unit.
[0020] FIGS. 6A is a top plan view of the vertical heat treatment
unit of FIG. 4.
[0021] FIG. 6B is a cross-sectional view of the vertical heat
treatment unit of FIG. 4 illustrating the operation of the
carousel.
[0022] FIG. 6C is a side elevational view of the vertical heat
treatment unit of FIG. 4 illustrating the forced air flow
therethrough.
[0023] FIGS. 7A-7C are perspective views of example embodiments of
nozzle configurations for use in the vertical heat treatment
units.
[0024] FIGS. 8A and 8B are side elevational views of yet another
embodiment of the vertical heat treatment unit of the present
invention in which the castings are conveyed along stacked,
laterally extending conveyor mechanisms.
[0025] FIG. 9A is a top plan view of yet another embodiment of a
vertical heat treatment unit according to the principles of the
present invention.
[0026] FIG. 9B is a side elevational view, with parts broken away,
of the embodiment of the vertical heat treatment unit of FIG.
9A.
[0027] FIG. 9C is a side elevational view of the embodiment of the
vertical heat treatment unit of FIG. 9A, taken in cross section
along lines B-B of FIG. 9A.
[0028] FIG. 9D is a side elevational view schematically
illustrating an alternative embodiment of the loader of the
vertical heat treatment unit of FIGS. 9A-9B.
[0029] FIG. 10A-10B are top plan views of a further embodiment of a
vertical heat treatment unit according to the principles of the
present invention.
[0030] FIGS. 11A-11B are side elevational views illustrating the
vertical heat treatment unit of FIGS. 10A-10B.
[0031] FIG. 12 is a graphical comparison of the processing of a
casting utilizing a conventional heat treatment process and system
versus the system and process of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Referring now in greater detail to the drawings in which
like numerals refer to like parts throughout the several views,
FIGS. 2A-2B schematically illustrates an exemplary integrated metal
processing facility or system 5 including the vertical heat
treatment unit or "cell unit" 10 according to the present invention
for processing metallurgical castings. Metal casting processes
generally are known to those skilled in the art and a traditional
casting process will be described only briefly for reference
purposes. It will be understood by those skilled in the art that
the present invention can be used in any type of casting process,
including metal casting processes for forming aluminum, iron,
steel, and/or other types of metal and metal alloy castings. The
present invention thus is not and should not be limited solely for
use with a particular casting process or a particular type or types
of metals or metal alloys.
[0033] As illustrated in FIG. 2A, a molten metal or metallic alloy
M typically is poured into a die or mold 11 at a pouring or casting
station 12 for forming a casting 13, such as a cylinder head,
engine block, or similar cast part as illustrated in FIG. 3. A
casting core 14 formed from sand and binder, such as a phenolic
resin or other known binder materials, can be received or placed
within the mold 11 to create hollow cavities and/or casting details
or core prints within the casting. Each of the molds alternatively
can be a permanent mold or die, typically formed from a metal such
as steel, cast iron, or other material as is known in the art. Such
molds may have a clam-shell style design for ease of opening and
removal of the casting therefrom. Alternatively still, the molds
can be "precision sand mold" type molds and/or "green sand molds",
which generally are formed from a sand material such as silica sand
or zircon sand mixed with a binder such as a phenolic resin or
other binder as is known in the art, similar to the sand casting
cores 14. The molds further may be semi-permanent sand molds, which
typically have an outer mold wall formed form sand and a binder
material, a metal such as steel, or a combination of both types of
material.
[0034] Additionally, the molds may be provided with one or more
user openings (not shown) to serve as reservoirs for molten metal.
These reservoirs supply extra metal to fill the voids formed by
shrinkage as the metal cools and passes from the liquid to the
solid state. When the cast article is removed from its mold, the
solidified metal in the opening remains attached to the casting as
a projection or "riser" (not shown). These risers generally are
non-functional and are subsequently removed, typically by
mechanical means.
[0035] It will be understood that the term "mold" will be used
hereafter to refer generally to all types of molds, including,
without limitation, those discussed above, including permanent or
metal dies, semi-permanent and precision sand mold types, and other
metal casting molds, except where a particular type mold is
indicated. It further will be understood that in the various
embodiments discussed below, unless a particular type of mold
and/or heat treatment process is indicated, the present invention
can be used for heat treating castings that have been removed from
their permanent molds, or that remain within a sand mold for the
combined heat treatment and sand mold break-down, removal, and sand
reclamation.
[0036] A heating source or element, such as a heated air blower,
gas-fired heater mechanism, electric heater mechanism, fluidized
bed, or any combination thereof also may be provided adjacent the
pouring station for preheating the molds. Typically, the molds are
preheated to a desired temperature depending upon the metal or
alloy used to form the castings. For example, for aluminum, the
mold may be preheated to a temperature of from about 400.degree. C.
to about 600.degree. C. The varying preheating temperatures
required for preheating the various metallic alloys and other
metals for forming castings are well known to those skilled in the
art and can include a wide range of temperatures above and below
from about 400.degree. C. to about 600.degree. C. Additionally,
some mold types require lower process temperatures to prevent mold
deterioration during pouring and solidification. In such cases, and
where the metal process temperature should be higher, a suitable
metal temperature control method, such as induction heating, may be
employed.
[0037] Alternatively, the molds may be provided with internal
heating sources or elements for heating the molds. For example,
where a casting is formed in a permanent type metal die, the die
may include one or more cavities or passages formed adjacent the
casting and in which a heated medium such as a thermal oil or other
fluid material is received and/or circulated through the dies for
heating the dies. Thereafter, thermal oils or other suitable media
may be introduced or circulated through the die, with the oil being
of a lower temperature, for example, from about 250.degree. C. to
about 300.degree. C., to cool the casting and cause the casting to
solidify. A high temperature thermal oil, for example, heated to
from about 500.degree. C. to about 550.degree. C., then may be
introduced and/or circulated through the die to arrest cooling and
raise the temperature of the casting back to a soak temperature for
heat treating. The pre-heating of the die and/or introduction of
heated media into the die may be used to initiate heat treatment of
the casting. Further, preheating helps maintain the metal of the
casting at or near a heat treatment temperature to minimize heat
loss as the molten metal is poured into the die, solidified, and
transferred to a subsequent processing station for heat treatment.
If additionally desired, the casting also may be moved through a
radiant chamber or zone to prevent or minimize cooling of the
casting.
[0038] As shown in FIG. 3, each of the molds 11 generally includes
side walls 16, an upper wall or top 17, a lower wall or bottom 18,
which collectively define an internal cavity 19 in which the molten
metal is received and formed into the casting 13. A pour opening 21
generally is formed in the upper wall or top 17 of each mold and
communicates with an internal cavity for passage 22 of the molten
metal through each mold and into its internal cavity 19 at the
pouring station. As indicated in FIG. 2A, the pouring station 12
generally includes a ladle or similar mechanism 23 for pouring the
molten metal M into the molds 11. The pouring station 12 further
can include a conveyor, carousel, or similar conveying mechanism,
that moves one or more molds from a pouring or casting position,
indicated by 24 in FIG. 2A, where the molten metal is poured into
the molds, to a transfer point or position 26 (FIG. 2B), at which
the castings can be removed from their molds or transferred while
remaining in their molds from the pouring station to the vertical
heat treatment unit 10 for heat treatment. Prior to and/or during
such transfer, the molten metal is allowed to cool to a desired
extent or temperature within the molds as needed for the metal to
sufficiently solidify into the castings. The castings then are heat
treated at a desired heat treatment temperature for a time
sufficient to achieve desired mechanical properties thereof.
Thereafter, the castings generally will be removed and transferred
to a quench unit or station 28, which can be part of or can be a
separate station positioned adjacent or downstream from the
vertical heat treatment unit 10 as illustrated in FIG. 2A.
[0039] As indicated in FIG. 2B, the castings can be transferred
from their pouring stations 12, either within their molds or after
removal and placed on a transfer line 31, such as a monorail or
similar conveying mechanism, that transfers or conveys the castings
in series or in batches to one or more loading carousels 32. The
carousels 32 generally can include a series of receiving bins or
trays 33 and a transfer mechanism 34 such as a robot, crane, boom,
or other similar device. The transfer mechanism 34 then feeds the
castings, or the molds with the castings therein, into one or more
vertical heat treatment units 10 for solution heat treatment of the
castings.
[0040] It has been discovered that as the metal of the casting is
cooled down, it reaches a temperature or range of temperatures
referred to herein as the "process control temperature" or "process
critical temperature." Below such process control temperature(s),
the time required to both raise the castings to the heat treating
temperature and perform the heat treatment is significantly
increased. It will be understood by those skilled in the art that
the process control temperature for the castings being processed by
the present invention will vary depending upon the particular metal
and/or metal alloys being used for the castings, the size and shape
of the castings, and numerous other factors.
[0041] In one aspect, the process control temperature may be about
380.degree. C.-480.degree. C. and as low as about 300.degree.
C.-325.degree. C. or less for some alloys or metals. In another
aspect, the process control temperature may be from about
400.degree. C. to about 600.degree. C. In another aspect, the
process control temperature maybe from abut 800.degree. C. to about
1100.degree. C. In still another aspect, the process control
temperature may be from about 1000.degree. C. to about 1300.degree.
C. or more for some alloys or metals, for example, iron. In one
particular example, an aluminum/copper alloy may have a process
control temperature ranging from about 300.degree. C. to about
480.degree. C. In this example, the process control temperature
generally is below the solution heat treatment temperature for most
aluminum/copper alloys, which typically is from about 427.degree.
C. to about 495.degree. C. While particular examples are provided
herein, it will be understood that the process control temperature
will vary depending upon the particular metal and/or metal alloys
being used for the castings, the size and shape of the castings,
and numerous other factors.
[0042] When the metal of the castings is within the desired process
control temperature range, the casting typically will be cooled to
sufficiently solidify as needed or desired. For example, depending
on the alloy formation or metal composition of the castings,
castings made from aluminum alloys generally will need to cool to
about 460.degree. C.-425.degree. C. to enable sufficient
solidification so that the castings can be gripped and manipulated,
i.e., removed from their molds/dies and/or transferred to the
vertical heat treatment unit or line as needed. This solidification
temperature will be understood as varying and can be determined as
understood by those skilled in the art based on the formulation(s)
of the metals or metal alloys being cast. However, if the metal of
the castings is permitted to cool below its process control
temperature, it has been found that the heat treatment time for the
casting is meaningfully impacted. For example, for some metals or
metal alloys, the castings may need to be heat treated for at least
about one to four additional minutes of heat treatment time for
each minute that the temperature of the metal of the castings is
cooled below the process control temperature, for example, from
about 475.degree. C. to about 495.degree. C. for aluminum/copper
alloys, or from about 510.degree. C. to about 570.degree. C. for
aluminum/magnesium alloys, to achieve the desired heat treatment
properties for the castings. Thus, if the castings cool below their
process control temperature for even a short time, the time
required to heat treat the castings properly and completely may be
increased significantly.
[0043] In addition, it should be recognized that in a batch
processing system, where several castings are processed through the
heat treatment station in a single batch, the heat treatment time
for the entire batch of castings generally is based on the heat
treatment time required for the casting(s) with the lowest
temperature in the batch. As a result, if one of the castings in
the batch being processed has cooled to a temperature below its
process control temperature, for example, for about ten minutes,
the entire batch typically will need to be heat treated, for
example, for as much as at least an additional forty minutes or
more to ensure that all of the castings are heat treated properly
and completely.
[0044] Various aspects of the present invention therefore, are
directed to an integrated processing facility or system 5 (FIG.
2A-2B) and methods of processing metal castings. The various
systems are designed to move and/or transition the castings (within
or apart from their molds) from the pouring station 12 to the
vertical heat treatment system or cell unit 10, while arresting
cooling of the molten metal to a temperature at or above the
process control temperature of the metal, but below or
approximately equal to the desired heat treatment temperatures
thereof to allow the castings to solidify. Accordingly, various
aspects of the present invention include systems for monitoring the
temperature of the castings to ensure that the castings are
maintained substantially at or above the process control
temperature.
[0045] For example, thermocouples or other similar temperature
sensing devices 36 (FIG. 2A) or systems can be placed on or
adjacent the castings at spaced locations along the path of travel
of the castings from the pouring station to a vertical heat
treatment unit or cell unit 10 to provide substantially continuous
monitoring as indicated in FIG. 2A. Alternatively, periodic
monitoring of the castings along their path of travel at selected
intervals determined to be sufficiently frequent, may be used. Such
sensing devices may be in communication with a controller 37 that
can be linked to and in control of one or more heat sources 38
positioned at desired or predetermined locations along the path of
the castings from the pouring station 11 to the vertical heat
treatment unit 10. For example, the heat sources could be
positioned at desired locations such as along the transfer line 31
(FIG. 2B). A heat source also can be positioned on or adjacent the
robot or other transfer mechanism 34 for the loading carousel(s) 32
for applying heat to the castings during transfer to the vertical
heat treatment unit.
[0046] The temperature measuring or sensing device(s) 36 and the
operation of the heat source(s) 38 can be controlled or coordinated
to substantially arrest cooling of the castings and apply heat as
needed to maintain the temperature of the castings substantially at
or above the process control temperature for the metal of the
castings. It also will be understood that the temperature of the
castings can be measured at one particular location on or within
the castings, can be an average temperature calculated by measuring
the temperature at a plurality of locations on or within the
castings, or may be measured in any other manner as needed or
desired for a particular application. Thus, for example, the
temperature of the castings may be measured at multiple locations
on or in the casting and/or mold therefore, and an overall
temperature value may be calculated or determined to be the lowest
temperature detected, the highest temperature detected, the median
temperature detected, an average of the detected temperatures, or
any combination or variation thereof.
[0047] A first embodiment of the integrated facility 5 and vertical
heat treatment system or cell unit 10 for processing metal castings
therethrough is illustrated in FIGS. 1, 2A, 2B, and 4-6C. FIGS.
8A-11C illustrate additional, alternative embodiments of the
vertical heat treatment unit 110, 150, and 200, respectively, for
heat treating castings. Still further, FIGS. 7A-7C illustrate
various nozzle configurations for fluid media nozzles/applicators
for applying heat to the castings in the vertical heat treatment
units according to the present invention. It also will be
understood by those skilled in the art that the principles of the
present invention can be applied equally to batch type and
continuous processing type facilities for castings. The embodiments
described hereinafter therefore are not and should not be limited
only to continuous or batch-type processing facilities. The present
invention also can be utilized for facilities in which the castings
are to be removed from their dies before heat treatment, as well as
for "2-in-1," 3-in-1," and/or "6-in-1" or other, similar processes
wherein the castings are placed in the vertical heat treatment unit
while still inside their sand molds for breakdown, removal and/or
reclamation of the molds and sand cores in conjunction with heat
treatment of the castings. In addition, it further will be
understood by those skilled in the art that various features of the
embodiments discussed hereafter and illustrated in the drawings can
be combined to form additional embodiments of the present
invention.
[0048] In an exemplary system as illustrated in FIGS. 2A and 2B,
the castings are transferred, either remaining within their molds
or after removal therefrom, from the transfer positions 26 (FIG.
2A) of their pouring stations 12 to the transfer line 31 or
directly to an adjacent vertical heat treatment unit 10 by a
transfer mechanism 34. The transfer system or mechanism 34
typically includes a robotic arm 39 or crane, although it will be
understood by those skilled in the art that various other systems
and devices for moving the castings and/or molds, such as an
overhead boom or hoist, conveyor, pushing rods, or other similar
material handing mechanisms also can be used. As indicated in FIG.
2A, the robotic arm 39 or other transfer mechanism generally
includes an engaging or gripping portion or clamp 41 for engaging
and holding the molds or castings, and a base 42 on which the
robotic arm is pivotally mounted so as to be moveable between the
transfer point 26 (FIG. 2B) of the pouring station and the transfer
line indicated by 31. In addition, as shown in FIG. 2B, the
transfer line 31 also can be used to transfer molds and/or castings
from multiple pouring stations 12 to multiple vertical heat
treatment units 10.
[0049] The castings can be transferred from their pouring
station(s) 12 to a loading carousel 32, where an additional
transfer mechanism 34 such as a robotic arm, crane, boom, or
similar mechanism, such as already in use at the facility,
generally will pick up the molds with their castings contained
therein, or can remove the castings 13 (FIG. 3) from their molds 11
and feed the castings to an associated vertical heat treatment unit
10. Thus, the same manipulator or transfer mechanism can be used
for removing the castings from the pouring station and for
introducing the castings into the vertical heat treatment unit 10.
Additionally, one or more heat sources or heating elements 38 (FIG.
2A) can be positioned adjacent the transfer point (not shown)
and/or along the transfer path for the castings to apply heat to
the castings as needed to maintain the castings at or above their
process control temperatures. These heat sources typically can
include any type of heating element or source such as conductive,
radiant, infrared, convective, and direct impingement types of heat
sources. As illustrated in FIG. 2A, multiple heat sources also can
be used, positioned to most effectively apply heat to the castings
during a transfer operation from the pouring station to the heat
treatment line.
[0050] Typically, in the case of permanent or metal dies or molds,
the molds will be opened at the transfer point and the castings
removed by the transfer mechanism. The same transfer mechanism then
can transfer the castings to the transfer line 31 or directly to
one or more vertical heat treatment units or systems 10 of the
integrated processing facility 5. As the molds are opened and the
castings removed, the heat sources can apply heat directly to the
castings to arrest or otherwise control the cooling of the castings
during their exposure to the ambient environment of the foundry or
plant, as the castings are being transferred to the heat treatment
unit, to maintain the castings substantially at or above the
process control temperature of the metal of the castings.
[0051] For the processing of castings that are being formed in
semi-permanent or sand molds, in which the castings typically
remain within their molds during heat treatment, during which the
molds are broken down by the thermal degradation of the binder
material holding the sand of the mold, the transfer mechanism may
transfer the entire mold with the casting contained therein, from
the transfer point to the inlet conveyor. The heat source thus may
continue to apply heat to the mold itself with the amount of heat
applied being controlled to maintain the temperature of the
castings inside the mold at levels substantially at or above the
process control temperature of the metal of the castings without
causing excessive or premature degradation of the molds.
[0052] A first embodiment of the vertical heat treatment unit or
cell unit of the present invention generally is illustrated in
FIGS. 4-6C. As shown, the vertical heat treatment unit 10 generally
can be a vertically oriented, free-standing "cell unit," according
to the invention, having a significantly reduced footprint such
that the amount of plant floor space required is minimized, while
still accommodating a desired amount of castings to be processed.
The vertical heat treatment unit thus also can be positioned in
close proximity to the pouring station(s) supplying castings
thereto. In the present embodiment shown, the vertical heat
treatment unit can be approximately 20-30 feet in height, although
each vertical heat treatment unit also can be constructed with
greater or lesser heights depending upon the required capacity
and/or sizes of the castings being processed.
[0053] The vertical heat treatment unit 10 includes an upstanding
furnace 50 supported by a surrounding frame 51. As previously
noted, the furnace can be formed with varying heights and typically
can be approximately 20-30 feet in height, with the height and
width of the furnace chamber being varied as needed and generally
being designed to accommodate a desired number of castings, i.e.,
10-20 or more rows of 1-5 castings generally received in each row
or batch for batch processing, although the castings also can be
processed individually or in larger batch sizes as needed or
desired. The vertical orientation and ability to vary the height of
the furnace chamber of the vertical heat treatment unit 10 of the
present invention depending upon the application and/or
facility/setting for its use, thus can enable up to an
approximately a 75% smaller footprint over many conventional heat
treatment units.
[0054] As shown in FIGS. 4-5A and 6B, the furnace 50 includes a top
portion 52, substantially flat side walls 53, the interior surfaces
54 (FIGS. 5A and 6B-6C) of which typically will be formed from or
lined or coated with a radiant material so as to reflect direct
heat inwardly toward the castings. The radiant material of the
radiant interior walls or surfaces 54 may be metal, telefilm,
ceramic, composite or other similar high temperature enduring
material capable of radiating heat. These radiant coatings or
materials generally form a non-stick surface on the walls and
ceiling of the furnace, and as the walls and ceiling of the radiant
chamber are heated, the heat tends to radiate inwardly toward the
castings, while at the same time, the surfaces of the walls and
ceiling generally can be heated to a temperature sufficient to burn
off waste gases and residue such as soot, etc., resulting from the
combustion of the binders of the sand molds and/or sand cores to
prevent collection and buildup thereof on the walls and ceiling of
the radiant furnace. The furnace 50 further includes a lower or
bottom portion 56 having inwardly sloped side walls 57 that
terminate at a substantially flat bottom 58. As indicated in FIG.
6B, the lower portion 56 also can include a fluidizer 59 positioned
therealong for fluidizing and assisting in substantially completing
the breakdown of the remaining binder materials from the sand being
collected from the sand cores and sand molds of the castings, and a
conveying mechanism 61 (FIG. 6C) for thereafter transporting the
reclaimed sand away for reuse.
[0055] As also indicated in FIG. 6B, the furnace 50 further can
include upper and lower sections 62 and 63 that serve to help
define a radiant furnace chamber 64 through which the castings 13
are conveyed for heat treatment and/or de-coring and mold removal.
As further indicated in FIG. 6B, the upper and lower portions 62
and 63 taper or slope inwardly, with the upper sections 62 defining
a narrowed upper air passage 66 for the passage of heated air flows
directly therethrough, while the lower section 63 defines a narrow
outlet passage 67 through which sand from the sand cores and/or
sand molds of the castings is directed into the bottom or lower
portion 56 of the furnace 50. Still further, as indicated in FIGS.
5A-5B, and 6B, an inlet/outlet port or opening 69 generally is
formed through one of the side walls 53 (FIG. 6B) and radiant walls
54 for ingress and egress of the castings into and out of the
furnace chamber 50. A door or other cover mechanism 71 is provided
for controlling access to the furnace.
[0056] As additionally indicated in FIGS. 4, 6A, and 6B, a
manipulator 75 will be mounted along one side of the vertical heat
treatment unit 10 in a position for receiving the castings from
their associated loading carousel 32 (FIG. 2B) or directly from the
transfer line 31. The manipulator 75 generally is moveable
horizontally and vertically as needed to lift, move, insert, and
withdraw the castings into and out of the furnace. As indicated in
FIGS. 4 and 6B, the manipulator 75 typically includes one or more
lift plates or forks 76 mounted to a motorized carriage 77 that can
ride on guide rails 78 for picking up and moving the castings into
the port or opening 69 (FIG. 6B) of the furnace chamber 50.
[0057] As indicated in FIGS. 5A-5B and 6B, within the radiant
chamber 64 of the furnace 50 of the vertical heat treatment unit 10
is a vertically oriented carousel or "ferris wheel" type conveying
mechanism 81 having a series of platforms, racks, or trays 82
(hereinafter, collectively, the "tray") mounted on chains 83 that
are rotated around large drive sprockets 84/84' driven by variable
speed, reversible motors (not shown) for driving the conveying
mechanism 81 at varying speeds and in a stepped fashion. Typically,
for loading/unloading operations, as the castings 13 are received
within the furnace 50, and/or after removal of a group or set of
heat treated castings, the conveying mechanism 81 generally will be
operated in a controlled stepping, up and down type motion, i.e.,
moving the rocks of the conveying mechanism (in direction of arrow
86' of FIG. 6B) to load a next casting or series of castings
therein, up one position and after the castings are received
therein, rotating the conveying mechanism downwardly so a to move
the racks or sets of racks two positions up from the just-loaded
rack(s) into a position for unloading, as needed, heat treated
castings therein, (in the direction of arrow 86, FIG. 6B) during
loading and unloading operations. Thereafter during normal
operation, the castings will be conveyed in a substantially
elliptical path down and around the lower sprocket 84' and upwardly
and over the upper sprocket 84 for heat treatment. The stepping up
one, down two, motion of the conveying mechanism helps ensure a
sufficient separation between the incoming ("colder") castings and
the hottest castings within the furnace to help substantially
reduce or prevent heat transfer/loss between the hottest and
"colder" castings to enable completion of the heat treatment of
such hotter castings.
[0058] As further illustrated in FIGS. 4-6C, the furnace 50
generally includes one or more heat sources 90, here illustrated as
fans or blowers 91 positioned adjacent the upper end of the furnace
50. The blowers 91 direct a heated media such as air or other gases
or fluids into the furnace so as to create a turbulent heated fluid
flow that passes about the castings as the castings are conveyed
along their heat treatment path by the conveying mechanism 81
(FIGS. 5A, 5B, and 6B). The blowers or fans 91 further can be
utilized in conjunction with other heat sources such as radiant or
infrared heaters, gas fired burners or other types of heat sources
to create a heated environment within the furnace for heating the
castings to their solution heat treatment temperature. In addition,
where the castings are processed in their sand molds, the
application of heat and the turbulent heated fluid flow about the
castings and downwardly to the bottom of the furnace 50, as
indicated in FIGS. 6B and 6C, helps facilitate the decomposition
and combustion of the binder materials of such sand cores and sand
molds so as to cause them to combust, pyrolize or otherwise be
driven off and the sand removed from the castings and directed
downwardly to the lower portion 56 of the furnace for collection
and removal as indicated in FIG. 6C.
[0059] In another aspect, additional or alternative heat sources 90
can be mounted within the radiant walls 54, positioned at desired
intervals therealong for directing high pressure fluid flows at the
castings within the trays of the conveying mechanism, as
illustrated in FIG. 6B, or as conveyed individually or in discrete
groups, such as illustrated in FIGS. 9A-11B. These heat sources 90
can include high velocity blowers or nozzle assemblies 92
positioned at desired distances with respect to the known
center-lines of the castings, including high pressure blowers or
nozzles positioned at desired distances with respect to the known
center-lines of the castings as they are conveyed within the trays
82 of the conveying mechanism 81, through the radiant chamber of
the furnace. The location and design of the nozzle or blower
assemblies 92 along the radiant walls 54 of the furnace 50, as well
as the actual distance that the pressurized fluid media directed
from such blowers needs to travel to impinge the castings and/or
the sand cores within the castings, such as passing through core
openings therein, the design of the flow pattern, the fluid media,
and other flow parameters of the fluid media directed from the
nozzle openings or ports 93 (FIGS. 7A-7C) generally will depend on
the type and size of the work piece, as well as the size of the
nozzles themselves.
[0060] According to one aspect of the invention, at least one of
the nozzles 92, blowers or other impingement devices can have a
nozzle opening or port 93 in the range of about 1/8 inch to about 6
inches in diameter or width, and in particular, the nozzles can
have one or more openings or ports 93 having a diameters of less
than about 1-1.5 inches to about 4 inches and can extend a length
of approximately 10''-26'' depending on the distances from the
nozzles to the castings. The diameters of the nozzle openings or
ports 93 can be fixed, although variable size nozzles also can be
used, and further will be dependent upon the desired or needed
velocities of the fluid media flows striking or impinging the
castings and their sand cores as desired or needed, as well as the
size of the core openings at which and through which the fluid
flows are directed. Alternatively, as indicated in FIGS. 7A and 7B,
the nozzles 92 also can include an elongated slotted opening or
port 94 for applying a broader or extended fluid flow along an
expanded area or over a series of locations rather than more
localized applications to specific points or areas of the castings.
Accordingly, while certain nozzle opening configurations, widths
and/or ranges of widths or diameters are set forth herein, it will
be understood by those skilled in the art that any suitable
impingement device or nozzle diameter and/or configurations can be
used in accordance with the present invention to achieve the
desired results. Thus, other nozzle opening diameters and/or
configurations are also contemplated hereby.
[0061] FIGS. 7A-7C illustrate various nozzle configurations or
arrangements for applying the heated fluid media to the castings.
In one embodiment shown in FIG. 7A, an upper nozzle assembly 92A is
formed with a series of large, medium or small nozzle openings or
ports 93 arranged at selected locations along the plenum 95.
Typically, the nozzle ports of the upper nozzle generally will be
arranged at locations approximately corresponding to the core
openings or other desired locations formed along the upper surface
of the casting, so as to apply a heated fluid media, such as heated
air or other fluids, primarily directed at selected locations
and/or providing fluid velocity flows across the remainder of the
upper surface of the castings. As also indicated in FIG. 7A, a
lower nozzle assembly 92B generally will be positioned beneath the
casting for applying heated fluid media flow at the bottom or lower
portion of the casting. In the embodiment illustrated in FIG. 7A,
the lower nozzle assembly 92B generally comprises a slotted nozzle
port 97 having an elongated slotted opening. The slotted nozzle
port 97 can extend substantially along the length of its plenum 95,
typically for a length approximately equivalent to the largest or
longest casting to be treated. For example, the slotted opening 94
can extend approximately 10-15 inches in length (although greater
or lesser lengths also can be used), and generally can be
approximately 0.5 inch to 1 inch wide, although greater or lesser
widths also can be utilized depending upon the penetration
velocities desired or needed by the fluid media flow being applied
by the nozzle assembly 92B.
[0062] FIG. 7B illustrates a further example embodiment of a nozzle
configuration arrangement 92 that can be utilized in the vertical
heat treatment unit according to the principles of the present
invention. In this embodiment, a series of four nozzle assemblies
92A-92D are indicated, although greater or lesser numbers of nozzle
assemblies also can be used. The upper or top nozzle assembly 92A
is shown with a series of varying size nozzle ports or openings
93/93', which further can be arranged as singles for directing
fluid flows towards specific locations or openings along the upper
top surface of the casting. The remaining nozzle assemblies 92B-92D
are illustrated at having slotted openings 94, and are arranged or
positioned along the bottom and side surfaces, respectively, of the
casting. Such a nozzle assembly can be provided in a chamber or
along a conveyor or other guiding mechanism, along which the
castings are conveyed through various embodiments of the vertical
heat treatment unit such as discussed more fully below with respect
to the embodiments of the vertical heat treatment unit as
illustrated in FIGS. 8A-11D. The nozzle assemblies 92B-92D (FIG.
7B) are illustrated with a slotted nozzle openings 94, although it
will be understood that one or more of the additional nozzle
assemblies can be provided with individual, localized ports or
openings, and similar configurations to that of the upper nozzle
assembly 92A.
[0063] FIG. 7C illustrates yet another example embodiment of a
nozzle arrangement in which an upper nozzle assembly 92A is
positioned above the upper surface of a casting, while a lower
nozzle assembly 92B applies a heated fluid media flow across
desired locations along a bottom surface of the casting. In this
embodiment, the upper nozzle assembly includes ports or openings
93/93' and can comprise small, medium, or large diameter openings
or ports and are generally spaced along or across the upper surface
of the castings for applying heated fluid media at varying
velocities across or at differing locations along the upper surface
of the casting. For example, smaller diameter nozzle ports 93' can
be oriented or focused at core openings or recesses so as to
provide a high velocity, heated fluid flow at such core openings
for breaking up and dislodging sand cores, while the larger
diameter ports or openings 93 can provide heated media fluid flow
over a larger area or wider location along the upper surface of the
casting. Additionally, the lower nozzle assembly 92B is shown with
a series of small or medium diameter nozzle ports or openings 93'
(although larger diameter nozzle ports or openings also can be
used) in which nozzle ports are arranged at angles. Such nozzle
ports can be of varied lengths and be oriented at an angle with
respect to the bottom surface of the casting and can apply a high
velocity fluid flow across a larger area, or can be specifically
directed to certain locations, such as core openings in the
castings, as needed.
[0064] According to another aspect of the present invention, the
nozzle ports or openings 93/93'/94 generally can be positioned from
about 1-1.5 inches to about 10 inches or more away from the
castings, and more typically, can be located about 1 inch to about
6-8 inches from the casting in order to impinge and or blast fluid
into and around the molds, castings, and/or sand cores of the
castings so as to direct substantially full velocity or pressure of
the fluid media exiting the nozzle openings being substantially
maintained. Typically, it has been found that substantially the
full speed or velocity and/or pressure of the fluid media being
applied by the nozzles can be maintained at a distance from the
nozzle opening that is approximately five-seven times the diameter
of the nozzle. For example, if the nozzle opening is approximately
one inch in width or diameter, the full velocity of the fluid flow
generally will be substantially maintained for approximately
five-seven inches, after which the velocity will begin to
significantly dissipate or decrease. Thus, the nozzles generally
are positioned at locations spaced from known or projected
center-lines of the castings as the castings are conveyed within
the trays 82 (FIG. 5B) of the conveying mechanism 81 by a distance
of approximately five-seven times the nozzle opening diameter. It
will, however, be understood that while various distances and
ranges of distances are provided herein, each nozzle or impingement
device may be positioned at varying distances with respect to the
center-lines of the castings being processed or from a desired
point or area of effect of the fluid flow as needed to achieve the
desired results. Thus, numerous other possible positions or
separation distances between the castings and the nozzle are
contemplated hereby.
[0065] The fluid media applied by the nozzles 92 generally is
delivered at a high discharge flow velocity of approximately
4,000-40,000 feet per minute (ft/min), for example, in a range of
about 5,000-9,000 ft/min (approximately 50 m/sec) so as to impinge
against the castings and/or create a turbulent high temperature,
high velocity fluid flow through the furnace chamber. It also will
be understood that while there are velocities and ranges of
velocities provided above, other velocities also can be used in
accordance with the present invention, depending, for example, upon
the size and type of casting, to achieve the desired results. The
fluid media thus generally can be delivered to the castings and/or
the core contained therein at a rate of approximately 50-500
standard cubic feet per minute per foot from the nozzles, although
other flow rates also can be utilized or provided.
[0066] As a result, the fluid media is delivered to the castings,
and more particularly to the core openings at a substantially high
velocities so as to create significant turbulence and to enhance
the burnout of the binder materials for the sand cores and/or sand
molds of the castings to enhance the rapid breakdown thereof. The
velocities of the fluid flows also can be varied by the pressure
and volume of the fluid flow as well as the configurations and
sizes of the nozzle ports or openings. In addition, the fluid media
flow may be directed to specific portions of the castings and/or
sand molds to localize the fluid flows where needed. For example,
the fluid media may be directed at one or more faces of the
castings to enhance the effect of the impinging fluid media,
including being directed at the core openings to enhance the
breakdown and removal of the sand cores from the castings.
[0067] The following Table 1 illustrates a comparison of various
options or examples of different nozzle configurations. The fluid
media flow is applied in volumes of approximately 10.86 pounds per
minute of heated air from the upper or top nozzle assembly, and
similarly, approximately 10.86 pounds per minute of heated air
through the bottom or lower nozzle assembly, with the nozzles
arranged in configurations similar to those illustrated in FIGS. 7A
and 7C. The temperature of the heated air being applied was
approximately 1000.degree. F. or more.
TABLE-US-00001 Example 1 (4) 1.5'' diameter round nozzles at the
top of the casting (4) 1.5'' diameter round nozzles at the bottom
of the casting (8) 0.5'' diameter round nozzles along the bottom of
the casting The 1.5'' bottom nozzles were placed under the fire
place of the casting to get better air penetration. The 0.5''
bottom nozzles are placed below the intake ports which are around
the fireplace of the casting. Example 2 (1) 0.5'' wide .times. 15''
long slot along the top of the casting (1) 0.5'' wide .times. 15''
long slot along the bottom of the casting Example 3 (8) 1''
diameter round nozzles at 2'' spacing along the top of the casting
(8) 1'' diameter round nozzles at 2'' spacing along the bottom of
the casting The bottom nozzles were generally centered on the
fireplace of the casting Example 4 (8) 1'' diameter inclined round
nozzles along the top of the casting (1) 0.5'' wide .times. 15''
long slot along the bottom of the casting Example 5 (1) 0.5'' wide
.times. 15'' long inclined slot along the top of the casting (1)
0.5'' wide .times. 15'' long slot along the bottom of the casting
Air Velocity through Casting Cavities (fpm) Example 1 Example 2
Example 3 Example 4 Example 5 Velocity of impingement 6000
4000-4500 4500-5500 3000-3800 3000-4500 on upper side (under
nozzle) Velocity of impingement 3000-4000 N/A 2000-2300 2000-3000
3000-4500 on upper side (between nozzles) Velocity of impingement
N/A 1000-2000 N/A N/A N/A on upper side (under riser) Air Velocity
in upper area 4000-4800 3000-3500 2800-3200 1000-2500 900-1800
opposite the nozzles Velocity in the vertical 2000-4000 2000-4000
2300-4000 800-1000 1000-1300 passages connecting top and bottom
Best case velocity in 8500 6800 4000-5500 4000-5800 3500-5400
exhaust ports Worst case velocity in 8500 6800 2100-3400 N/A N/A
intake ports Best case velocity in intake 8500 6800 3000-4900
2000-4800 2000-5000 ports Worst case velocity in 8500 6800
1800-2200 N/A N/A intake ports
[0068] According to the velocities measured in the table, the
highest fluid flow velocities were achieved with the nozzle
configurations of Examples 1 and 2. However, given the general
configuration of most conventional types of castings that typically
will be treated in the vertical heat treatment units of the present
invention, it has been found that a combination of nozzle
configurations as disclosed in Options or Examples 1 and 2,
including the use of a slotted nozzle assembly along the bottom or
lower side of the casting and an upper nozzle assembly generally
having a series of nozzle openings or ports ranging from
approximately 0.5 to about 1.5 inches or larger in diameter and
arranged at desired locations across the upper surface for
providing localized and higher velocities across the upper surface
of the castings, generally can provide preferred heating coverage.
It will be understood by those skilled in the art, however, that
such nozzle configurations can be further varied, as needed,
depending on the design or configuration of the castings being
treated, and can provide additional heat treatment to certain
desired areas or locations of the castings as needed.
[0069] Still further, as indicated by arrows 98 and 98' in FIGS. 7A
and 7B, the castings, or the nozzles themselves, or both, also can
be oscillated, rotated, or otherwise moved at predetermined
intervals or through predetermined motions based upon the known
positioning of the castings, including the known center-line
positions thereof. Such oscillation of the nozzles and/or the
castings during application of the heated fluid flows has been
found to provide expanded fluid media impingement across the
castings and thereby achieve enhanced efficiency of the process.
Depending upon the sizes of the nozzles and the castings
themselves, the nozzles or the castings can be moved or oscillated
at rates ranging from about 5 feet per minute to upwards of
approximately 40 feet per minute, although other rates of movement
also can be used in accordance with the present invention to
achieve the desired results. Still further, the oscillation of the
castings and/or nozzles can be limited from about 3 inches to about
15 inches, up to about 36 inches in either direction, and can be
done relatively quickly, i.e., in about 2 seconds per revolution to
about 1 minute or at more controlled rates from about 1 minute to
about 10 minutes. However, it also will be understood that the
oscillation distances and cycle times can be varied as needed to
achieve the desired results.
[0070] Additionally, the temperatures of the fluid media being
directed at the castings by the nozzle assemblies or blowers 92
generally will be at elevated temperatures, typically from about
400.degree. C. to about 600.degree. C., or more depending upon the
metal or metal alloy being treated. The temperatures of the fluid
media being applied generally will be sufficient to promote and/or
cause the combustion (for example where air or oxygenated gas flows
are used for the fluid media) or pyrolyzing of the binder materials
of the sand cores and/or sand molds of the castings and to help
assist in heat treatment, but generally will be less than the
temperature at which the castings might be softened or
substantially raised above their solution heat treatment
temperature so as to potentially cause damage thereto. It also will
be understood that while a particular temperature range is
discussed herein, other temperatures also may be used to achieve
the desired results.
[0071] As further shown in FIG. 6C, a separator 96 also can be
provided adjacent the furnace 50. The separator 96 can be a
cyclonic separator that is in flow communication with the lower
portion or bottom 56 of the furnace 50, so as to draw off excess
air therefrom. As this waste air is passed through the separator
96, it will be filtered and thus substantially cleaned of
particulate matter such as sand, dust, and other debris.
Thereafter, the cleaned air can be re-circulated back to the fans
or blowers 91 at the top of the furnace 50 where it can be cleaned
and reused/redirected into the furnace or can be exhausted or
otherwise vented therefrom.
[0072] As shown in FIGS. 4 and 6B, the vertical heat treatment unit
additionally can be provided with a quench unit 28 mounted adjacent
or in front of the door 71 to the furnace 50 along the path of
movement of the castings into and out of the furnace by the
manipulator 75. The manipulator 75, after removal of the castings
from the furnace chamber of the vertical heat treatment unit, can
lower the castings into the quench unit 28 for quenching the
castings, and thereafter can remove the castings and deposit them
on the transfer line 31 (FIG. 2B) or other conveyance for
removal.
[0073] In an alternative embodiment of the vertical heat treatment
unit 110 shown in FIGS. 8A-8B, the vertical heat treatment unit 110
includes a furnace 111 having walls 112, ceiling 113, and a lower
portion 114, that includes downwardly sloping sections or walls 116
that terminate at a bottom or floor 117. The walls, ceiling, and
lower portion of the furnace 111 generally are formed from or
coated with a radiant material as discussed above with respect to
the embodiment of FIGS. 4-6C, and define a radiant furnace chamber
118 therein. A series of longitudinally extending conveyors 119,
which can include chain or slotted/belted conveyors having a series
of openings or slots 121 (FIG. 8B) defined therein will be
positioned in a vertically stacked arrangement. Each of the
conveyors 119 will extend longitudinally along the radiant chamber
118 of the furnace 111 as indicated in FIG. 8B and will be operated
at a desired rate as needed to complete the heat treatment of the
castings as they are passed through the radiant furnace chamber
118. It will be understood by those skilled in the art that while
only 2-3 conveyors 119 are illustrated in FIGS. 8B and 8A,
respectively, additional conveyors also can be provided in a
vertically stacked arrangement, with the furnace 111 of the
vertical heat treatment unit 110 being extended or increased in
size vertically to enable the loading of additional castings and
castings of varying sizes therein.
[0074] As shown in FIG. 8A, a series of heat sources 122 generally
are provided above and between the conveyors 119. The heat sources
can include conduction, convection, infrared or other radiant heat
sources, such as gas fired burners, and/or can include nozzles or
blowers that direct a flow of heated fluid media to the castings as
the castings are passed therebeneath on the conveyors 119 so as to
heat the castings to a solution heat treatment temperature for heat
treatment of the castings. The fluid media further can be applied
at substantially higher velocities from the nozzles as discussed
above, with the nozzles or heat sources being placed at
pre-determined distances with respect to the centerlines castings,
so as to direct fluid flows at desired portions of the castings,
for example, at and into core openings thereof to facilitate the
breakdown and pyrolization of any binder materials for the sand
cores and/or sand molds of the castings.
[0075] As further illustrated in FIG. 8A, any sand dislodged from
the sand cores and/or sand molds of the castings can be collected
and directed downwardly into the bottom portion 114 of the furnace
or along the downwardly sloping sections of the walls 116 thereof.
A fluidizer 123 also can be provided adjacent the floor 117 of the
bottom or lower portion 114 of the furnace 111 so as to fluidize
any collected sand and help further promote the substantially
complete breakdown and burnoff of any remaining binder materials so
that the sand materials can be substantially cleaned and reclaimed
for further use.
[0076] FIGS. 9A-9D illustrate yet another embodiment of the
vertical heat treatment unit 150 according to the principles of the
present invention. As illustrated FIGS. 9A-9D, the vertical heat
treatment unit 150 generally includes a furnace 151 mounted in the
vertically extending, upstanding arrangement and can extend between
10-30 feet in height, although greater or lesser heights also can
be used as needed or desired, depending on the application. The
furnace 151 generally includes a ceiling 152, vertically extending
side walls 153, and a lower portion 154 (FIG. 9B), including
downwardly sloping sections or walls 156 that extend inwardly and
downwardly toward a floor or bottom 157. The ceiling 152, side
walls 153, and lower portion 154 of the furnace 151 are generally
formed form or have applied thereto a radiant material, such as
discussed above with respect to the embodiment of FIGS. 4-6C, so as
to radiate heat inwardly therefrom toward the castings, and define
a radiant chamber 158 (FIGS. 9B and 9D) within the furnace 151.
Heat sources 159, such as one or more blowers 161 or fans, or other
heat sources such as convection or conduction heat sources,
including infrared or other radiant heat sources and/or gas fired
burners, etc. also can be used to introduce heat into the radiant
chamber and raise the temperature of the castings therein to their
solution heat treatment temperature.
[0077] As additionally shown in FIGS. 9B and 9C, a grid system 162,
having a series of chambers 163 formed therein, will be mounted
within the radiant chamber 158 of the furnace 151. The chambers of
the grid system 162 generally will be spaced apart or separated by
walls 164, typically including insulating and radiant materials to
prevent heat transfer or loss from hotter castings to cooler
castings that are in adjacent chambers or compartments on the same
row of the grid system 162. The floors and ceilings 166 and 167 of
each of the chambers or compartments 163 typically can have a
slotted construction, with a plurality of openings formed therein,
or can be substantially open, with the castings being received and
contained on rails 168 (FIG. 9C) or similar supports so as to allow
free flow of air, heat, and dislodged sand from the sand cores
and/or sand molds of the castings to pass therethrough and fall
through the entire grid system 162 for collection in the lower
portion 154 of the furnace 151. Additional heat sources also can be
provided along the floor and ceiling portions 166, 167 of each of
the chambers 163 to help provide additional, directed heat to the
castings. For example, such heat sources can include nozzles that
apply high velocity fluid media flows directed at desired portions
or sections of the castings, such as at core openings, thereof to
help facilitate the breakdown and dislodging of the sand from the
sand cores and sand molds of the castings.
[0078] As additionally illustrated in FIG. 9B and 9D, in this
embodiment of the vertical heat treatment unit 150, a gantry or
elevator type loader 175, which can include a crane, boom, or
robotic arm, generally is provided in the radiant chamber 158 of
the furnace 151. The loader 175 generally includes a platform or
support 176 on which one or more castings or molds, here shown as
four castings or molds 11/13, are received and will be moved
vertically and horizontally for introduction and removal of the
castings or batches of castings from the compartments or chambers
163 of the grid system 162, as illustrated in FIG. 9B. Typically,
the support platform 176 of the loader 175 will include a slot or
central opening in which the rails or supports of the chambers 163
can be received for removal of the castings from the support
platform of the loader after the loader has inserted the castings
into their assigned chamber. As further illustrated in FIG. 9B,
where the castings include risers or supports, the support platform
of the loader can include a rail or skid adapted to be inserted
within such openings in the castings and insert the castings on the
rails for a particular assigned chamber.
[0079] Alternatively, as illustrated in FIG. 9D, the loader 175 can
be positioned outside of the furnace 151. In this embodiment, the
loader 175 will be moveable into and out of the chambers or
compartments 163 of the grid 162 through associated compartment
openings 180. Each compartment opening or passage 180 will include
a door or cover 181 that is moveable between an open position (as
shown in FIG. 9D) for receiving the castings therein and a closed
position for sealing the compartment openings. The doors 181 can be
automatically engaged by sensors that activate a motor or hydraulic
or pneumatic lift mechanism, or could be engaged and opened by the
loader itself via a lift/positioner mechanism or extension on the
loader, which contacts and causes the door to open, after which the
doors can be allowed to close by gravity.
[0080] FIGS. 10A-11B illustrate still a further embodiment of the
vertical heat treatment system or cell unit 200 according to the
principles of the present invention. In this embodiment, the
vertical heat treatment unit 200 generally is illustrated as
including a substantially circular or octagonally-shaped
configuration, although other similar configurations also can be
provided, and generally includes a furnace 201 having a series of
chambers 202A-202D. The furnace 201 can extend to approximately
10-20 feet in height although it also can be formed at greater or
lesser heights as needed or desired, depending upon the
application, including the types of casting to be processed, as
well as the environment in which the vertical heat treatment unit
or cell unit is to be placed, while providing a reduced footprint
and the ability to place the cell unit in close proximity to the
pouring station(s).
[0081] As indicated in FIG. 10A, each of the chambers 202A-202D can
be formed with a substantially C or U-shaped configuration
including angled or curved walls 203 having inner surfaces 204
generally formed from or coated with a radiant material, such as a
ceramic material or other, similar heat resistant and heat
radiating material capable of withstanding high temperatures. The
walls 203 further can be hollow so as to define flow passages,
indicated by arrows 206, through which heated fluid flows, such as
heated air flows or other similar heated fluid media, are
passed.
[0082] As further illustrated in FIGS. 10A, 10B and 11B, a series
of heat sources 207, such as one or more blowers or forced air fans
208, generally are mounted along outer side walls 209 of the
furnace 201 of this embodiment of the vertical heat treatment 200,
with at least one heat source 207 being provided for each of the
chambers 202A-202D as indicated in FIGS. 10A and 10B. The heat
sources 207, which also can include sources such as convection or
conduction heaters, infrared or other radiant sources and/or gas
fired burners, etc., introduce heat into each of the radiant
chambers 202A-202D, such as via heated fluid media flows passing
along the passages, as indicated by 206, through the walls 203 of
each chamber and through openings 211 (FIG. 10A) formed in the
chamber walls 203.
[0083] It is further shown in FIGS. 10A, 11A, and 11B, each of the
furnace chambers 202A-202D generally includes a series of racks or
grid storage units 212 on which the castings 13 are received and
retained for heat treatment. The racks or grids 212 further can be
formed with or be positioned in a series of compartments or heating
chambers 213 in which one or more castings are received. The
compartments 213 typically include side walls 214 (FIGS. 10A and
11B) generally being formed from or coated with insulating and/or
radiant materials to prevent heat transfer or loss from hotter
castings to cooler castings in adjacent compartments on the same
row of racks or grids 212. The floors and ceilings of the
compartments 213 typically can have a slotted or substantially open
construction having a plurality of openings formed therein, with
the castings being supported on rails or tracks, or similar
supports. As a result, a substantially free flow of air, heat, and
dislodged sand from the sand cores and/or sand molds of the
castings is enabled through the entire rack or grid system 212 of
each furnace chamber and/or compartment for collection. The
compartments 213 in each of the furnace chambers further can
include additional heat sources 215, such as nozzles, blowers, or
other similar heaters for applying heated fluid flows into the
compartment, or can include conduction, radiant or other, similar
heat sources for applying heat both above and below the castings
within each of the compartments.
[0084] As indicated in FIGS. 11A and 11B, the furnace 201 farther
generally includes a lower or bottom portion 216 below each of the
furnace chambers. The bottom portions can have sloped walls to
facilitate collection of the dislodged mold/core sand and other
materials, such as is shown in FIGS. 11A, for reclamation and
recovery. Additional heat sources also can be provided in the lower
portion of each of the chambers, including fluidizers or nozzles
that apply high velocity fluid flows through the bed of the
collected sand to help facilitate the further combustion of the
binder materials of the sand cores and sand molds to help with the
further breakdown and recovery of the sand. Such reclaimed sand
then can be discharged via a discharge chute 217 and conveying
system 218. Still further, while each of the chambers can be
provided with a lower portion collection area 216, such as shown in
FIG. 11B, the furnace 201 also can be configured so as to have a
central collection area 216 at a lower point thereof, whereby the
sand from all the furnace compartments is directed to and collected
at such a central location.
[0085] As additionally illustrated in FIGS. 11A and 11B, in this
embodiment of the vertical heat treatment unit 200, a gantry or
elevator type loader 225, which can include a crane, boom, robotic
arm or other similar lifting mechanism, is located approximately
within the center of the furnace. The loader is moveable vertically
and horizontally, as well as being rotatable or pivotable about a
centrally extending axis, for delivering and removing the castings
13 from the compartments 213 of each of the racks or grid systems
212 of the furnace chambers. The loader 225 generally can include a
platform or support 226 on which one or more castings or molds with
castings therein 13/11 are received and carried for introduction
and removal of the castings or batches of castings in to/from each
of the compartments 213 of each furnace chamber. The support
platform 226 further can include clamping rails or similar supports
that can engage and clamp the castings from the sides thereof or
can engage the castings through one or more core openings.
Additionally, a heat source can be mounted so as to apply heat
through or along the support platform 226 as needed or desired for
helping speed the heating of the castings to their heat treatment
temperatures for treatment, and mold and/or sand core removal and
reclamation. Still further, if the castings include risers or other
supports, the support platform of the loader can include rails or
skids adapted to be inserted within such openings or for engaging
the risers or supports for loading and unloading operations.
[0086] As illustrated in FIGS. 10B and 11A, the loader 225
generally can receive the castings from an inlet mechanism 230. The
inlet mechanism 230 can include a reversible conveyor or series of
conveyors 231 in which the castings are fed individually or in
batches into the furnace 201, into a position where they can be
engaged by the loader 225, as indicated in FIG. 11A. Still further,
it is also possible to utilize more than one loader within the
furnace to further enhance or increase the efficiency of loading
and unloading the castings within the compartments of the furnace
chambers for heat treatment and/or sand mold removal and
reclamation.
[0087] As illustrated in FIG. 12, utilizing the vertical heat
treatment unit of the present invention, the heat treatment units
can be placed immediately adjacent or in close proximity to the
pouring stations for the castings, which thus enables more
efficient processing and heat treatment of the castings. Through
the use of the vertical heat treatment unit according to the
present invention, the castings can be removed from their pouring
stations and transferred substantially directly to a heat treatment
unit without the castings being unduly exposed to the ambient
environment that would allow the castings to cool substantially
below the process control temperature for the metal or metal alloy
from which the castings are being formed.
[0088] It can be understood by those skilled in the art that for
any given casting, the desired dendrite arm spacing is
substantially constant, with the interdiffusion coefficients of
various metals or metal alloys generally being known values. For
example, the interdiffusion coefficient (D) of copper and aluminum
is on the order of about 6.times.10.sup.-11cm.sup.2s.sup.-1 at
450.degree. C. and about 7.times.10.sup.-12 cm.sup.2s.sup.-1 at
400.degree. C. As will be understood by those skilled in the art,
the ratios of the interdiffusion coefficients can be evaluated to
estimate the differences in diffusion and thus corresponding heat
treatment times required for castings that are held at varying
temperatures. It is further understood that the diffusion distances
(which can be correlated to the desired dendrite arm spacings used
for certain metal alloys after heat treatment) can be expressed as
L= {square root over (Dt)}, wherein D=interdiffusion coefficient of
a metal alloy at a desired temperature, while t=Time. Accordingly,
for a casting for which the metal thereof has a process control
temperature of approximately 450.degree. C. (for example) if the
casting is allowed to drop below this predetermined process control
temperature, and to a temperature of approximately 400.degree. C.,
it theoretically can take approximately three (3) times longer to
heat treat the castings to achieve the desired properties (such as
a desired dendrite arm spacing) than if the casting is maintained
at or above its process control temperature of approximately
450.degree. C.
[0089] FIG. 12 is a graphical illustration of a comparison of a
process for forming a metal casting, including pouring, maintaining
the casting at or above its process control temperature from
pouring to heat treatment, then heat treating, quenching, and aging
the casting, which can be carried out utilizing a vertical heat
treatment unit according to the present invention, as compared to a
conventional type casting formation process in which the castings
are poured, and then heat treated, while the core and sand molds of
the castings are removed and broken down/reclaimed at substantially
the same time within the heat treatment furnace, and thereafter
quenched and later aged. The dark solid line indicates a process
utilizing the present invention, while the lighter colored line
illustrates the time required to process a casting according to
conventional casting processing methods.
[0090] As illustrated in FIG. 12, with the present invention, by
maintaining the casting substantially at or above its process
control temperature (PCT) and placing the casting into heat
treatment as quickly as possible via transfer to the "cell unit" or
vertical heat treatment unit formed according to the present
invention, which, due to its size and configuration can be
positioned adjacent or substantially in time with one or more
pouring stations, heat treatment of the casting can be accomplished
in approximately 98 minutes or less, as compared to over two hours
for the conventional process. It also can be seen that the casting
is generally able to be raised back up to a solution heat treatment
temperature more rapidly as compared to a conventional process.
Thus, while the conventional process may take upwards of 13-14
hours to finish pouring, solidifying, heat treating, quenching, and
aging a casting, the present invention enables a casting to be
formed and processed in about less than half that amount of
time.
[0091] Accordingly, as part of a casting process system in which
the temperature of the castings is monitored and controlled during
transition of the castings from pouring to heat treatment so as to
maintain the castings at or above a process control temperature for
the metal/metal alloys thereof up to heat treatment, the vertical
heat treatment system or cell unit of the present invention can not
only provide a substantially shorter heat treatment cycle, but also
will provide easier maintenance and labor savings and can support
increased casting complexity, while at the same time taking up a
much smaller footprint within the facility space of the metal
processing and thus enabling more diversification of the casting
being produced. The vertical heat treatment system or cell unit of
the present invention further can allow for the use of high
velocity treatment processes for enhancing the de-coring and mold
removal from the castings, in addition to enhancing and further
speeding of the heat treatment thereof. For example, with the
present invention, time for de-coring a casting can be reduced from
approximately 2-4 hours to approximately 40-75 minutes, with the
entire cycle time required for de-coring and heat treatment of a
casting up until quench being reduced to about an hour and a half
or less.
[0092] It will be readily understood by those persons skilled in
the art that, in view of the above detailed description of the
invention, the present invention is susceptible of broad utility
and application. Many adaptations of the present invention other
than those herein described, as well as many variations,
modifications, and equivalent arrangements will be apparent from or
reasonably suggested by the present invention and the above
detailed description thereof, without departing from the substance
or scope of the present invention.
[0093] Additionally, while the present invention is described
herein in detail in relation to specific aspects, it is to be
understood that this detailed description is only illustrative and
exemplary of the present invention and is made merely for purposes
of providing a full and enabling disclosure of the present
invention. The detailed description set forth herein is not
intended nor is to be construed to limit the present invention or
otherwise to exclude any such other embodiments, adaptations,
variations, modifications, and equivalent arrangements of the
present invention, the present invention being limited solely by
the claims appended hereto and the equivalents thereof.
* * * * *