U.S. patent application number 11/763468 was filed with the patent office on 2007-12-20 for methods and system for manufacturing castings utilizing an automated flexible manufacturing system.
Invention is credited to Paul M. Crafton, Scott P. Crafton, Ian French, Joseph H. Oczkowski, Shanker Subramaniam.
Application Number | 20070289713 11/763468 |
Document ID | / |
Family ID | 38683435 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289713 |
Kind Code |
A1 |
Crafton; Scott P. ; et
al. |
December 20, 2007 |
METHODS AND SYSTEM FOR MANUFACTURING CASTINGS UTILIZING AN
AUTOMATED FLEXIBLE MANUFACTURING SYSTEM
Abstract
A method and system for generating a production sequence for the
control of resources and production for metal castings of a
manufacturing plant. The system employs a transport system to
transfer the castings between a series of processing stations,
which could include heat treatment, quenching, decoring, demolding,
cleaning, machining, inspection, storage, etc., served by the
transport system. A series of guided vehicles moving along the
transport carry the castings between the processing stations. Each
guided vehicle includes an identifier monitored by a controller to
direct the castings to the next required processing station
according to a predetermined production sequence for the castings
thereon.
Inventors: |
Crafton; Scott P.;
(Marietta, GA) ; Crafton; Paul M.; (Kennesaw,
GA) ; Subramaniam; Shanker; (Marietta, GA) ;
French; Ian; (Kennesaw, GA) ; Oczkowski; Joseph
H.; (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: |
38683435 |
Appl. No.: |
11/763468 |
Filed: |
June 15, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60813938 |
Jun 15, 2006 |
|
|
|
Current U.S.
Class: |
164/4.1 ;
164/344; 164/76.1 |
Current CPC
Class: |
B22D 47/02 20130101 |
Class at
Publication: |
164/004.1 ;
164/076.1; 164/344 |
International
Class: |
B22D 46/00 20060101
B22D046/00; B22D 29/00 20060101 B22D029/00 |
Claims
1. A system for processing castings, comprising: a pouring station
for pouring molten metal into a mold to form the castings; a series
of processing stations downstream from said pouring station,
including at least one of a heat treatment station, quench station,
aging station, and a cleaning station; and a transport system
adapted to receive the castings from said pouring station and
direct the castings to one or more of said processing stations
according to a programmed processing sequence for the castings,
said transport system comprising: a conveying mechanism; a series
of guided vehicles, each including an identifier referencing said
processing sequence for at least one casting received thereon.
2. The system of claim 1 and wherein said identifier of each of
said guided vehicles comprises a wireless communication device.
3. The system of claim 2 and wherein said wireless communication
device comprises an RF transmitter.
4. The system of claim 1 and wherein each guided vehicle comprises
a carrier having at least one rack for receiving at least one
casting therein.
5. The system of claim 1 and wherein said conveying mechanism of
said transport system comprises an overhead monorail conveyor
adapted to receive said guided vehicles thereon.
6. The system of claim 5 and wherein said monorail conveyor further
comprises a guide track along which said guided vehicles are moved
and extending between said processing stations, said guide track
having a series of junction points at which said guided vehicles
can be redirected to selected ones of said processing stations
according to said processing sequence for the at least one casting
within each of said guided vehicles.
7. The system of claim 1 and wherein said transport system
comprises a guide track having a series of track segments extending
through each of said processing stations adapted to receive and
direct selected ones of said guided vehicles through said
processing stations.
8. The system of claim 1 and further comprising a system control
adapted to monitor said identifiers of said guided vehicles and
direct said guided vehicles between each of said processing
stations according to said processing sequence for the at least one
casting within each of said guided vehicles.
9. A method of manufacturing a series of metal castings,
comprising: pouring a molten metal into a series of molds;
solidifying the molten metal sufficiently to form the castings;
loading the castings on a series of guided vehicles of a transport
system; monitoring and identifying at least one set of castings on
each of the guided vehicles, and directing each guided vehicle
through one or more processing stations according to a
predetermined processing sequence for the castings loaded on each
guided vehicle.
10. The method of claim 9 and further comprising directing a series
of guided vehicles through a heat treatment station and heat
treating the castings.
11. The method of claim 10 and further comprising moving the guided
vehicles through a trimming station prior to heat treating the
castings.
12. The method of claim 9 and further comprising placing the guided
vehicles on a conveying mechanism for conveying the guided vehicles
with the castings thereon to selected processing stations according
to the predetermined processing sequence for the castings.
13. The method of claim 9 and wherein monitoring and identifying at
least one set of castings on each of the guided vehicles comprises
monitoring an identifier of each guided vehicle with a system
control, and in response, directing each guided vehicle along a
transport system through one or more selected ones of the
processing stations according to the predetermined processing
sequence for the castings on the guide vehicle associated with the
monitored identifier.
14. The method of claim 9 and wherein monitoring and identifying at
least one set of castings on each of the guided vehicles comprises
detecting an identifier for the set of castings, and in response,
transferring the set of castings into a selected processing station
according to the processing sequence for the castings associated
with the monitored identifier.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application is a formalization of
previously filed, co-pending U.S. provisional patent application
Ser. No. 60/813,938, filed Jun. 15, 2006. This patent application
claims the benefit of the filing date of the cited provisional
patent application according to the statutes and rules governing
provisional patent applications, particularly 35 USC .sctn.
119(e)(1) and 37 CFR .sctn..sctn. 1.78(a)(4) and (a)(5). The
specification and drawings of the provisional patent application
are specifically incorporated 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 process conditions
the metal or metal alloys of the castings to achieve the desired
physical characteristics of the castings as needed for a given
application.
[0003] In a conventional heat treatment system, a series of
castings can be placed within a basket and passed along a roller
hearth or similar conveying mechanism through one or more heating
chambers for a solution heat treatment. 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 baskets and conveying mechanism 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] However, 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,
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 in some applications as the "process
critical 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.
[0005] For example, as illustrated in FIG. 1, it has been found
that for certain types of metals, for every minute of time that the
castings drops below its process control temperature, more than one
minute, and in most cases at least about 3-4 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.
[0006] 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
[0007] Briefly described, the present invention generally relates
to a casting processing system for enabling the pouring, forming,
heat treating, cleaning, aging, quenching, and further processing
of castings formed from metal and/or metal alloys at enhanced rates
and efficiency, and with greater flexibility and control of
movement of the castings between various processing stations, as
compared with conventional casting processes in which castings are
processed in batches along a substantially uniform path through
heat treatment, quenching, etc. 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. A transfer
mechanism then typically will transfer the castings to a series of
guided vehicles, each generally including a series of racks and/or
baskets defining compartments in which the castings are received
for transport into and through a heat treatment station and/or
other processing stations, according to a pre-programmed processing
sequence or schedule for each casting or set of castings on the
guided vehicles. During this transition from the pouring station to
one or more downstream processing stations, the molten metal of the
castings generally is permitted to cool to an extent sufficient to
form the castings.
[0008] The guided vehicles generally are carried along their
predetermined processing paths through the various casting
processing stations in a vertically hanging arrangement supported
on a transport system, typically comprising an overhead gantry or
monorail conveyor, or other, similar type of conveying mechanism,
with the racks thereof being stacked vertically in one or more rows
mounted on a vertical support structure. Each of the guided
vehicles further generally will include an identifier, which can
include a bar code, alphanumeric tag, or other readable identifier
that can be attached to each of the racks or along the vertical
supports of the guided vehicles. Alternatively, the identifiers
also can include infrared or RF transceivers or tags, or other
sensors that provide a signal to various receivers or other reader
mechanisms mounted along the processing paths for the castings.
[0009] A system control monitors and automatically directs each of
the guided vehicles along a predetermined/pre-programmed processing
sequence or path for the castings of each guided vehicle through
the required processing stations for that particular set of
castings based upon the detection or reading of the identifiers of
the guided vehicles. For example, a first casting or set of
castings can be transported from the pouring station to a heat
treatment station and thereafter transferred to an aging or quench
station, while a second casting or series of castings can be
transferred first to trimming and/or mold removal stations prior to
heat treatment and quenching, or simply can be directed straight to
quenching and then aging, depending upon the desired properties for
the casting.
[0010] The overhead transport system further generally will include
an elongated track having a series of pathways or segments, and a
series of switches or junction points at which the guided vehicles
can be diverted into the various processing stations according to
their pre-programmed processing sequences. The transport system
segments or pathways can extend through the various processing
stations themselves, or can simply stop at the various processing
stations, whereupon a transfer mechanism can transfer the castings
directly into the processing stations, such as a heat treatment
unit, etc., for processing. Thereafter, the castings can then be
reloaded into a basket or rack of the guided vehicle at the
downstream end of the processing station.
[0011] The transport system also generally includes a drive system
for conveying the guided vehicles along their path of travel. This
drive system can be a constant drive, utilizing a substantially
constantly moving chain or belt, with each guided vehicle including
a carrier that is detachably engageable therewith to facilitate the
transfer of the automatic guided vehicles to different lines or
segments of the transport system track, so as to be transferable
into and through the different processing stations, as needed.
Alternatively, the transport system can include an electrified rail
or other, similar drive, and with the guided vehicles including
drive motors for driving the guided vehicles along the rails of the
transport system.
[0012] Various features, objects and advantages of the present
invention will become apparent to those skilled in the art upon a
review of the following detailed description, when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 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 falls below its
process control temperature.
[0014] FIG. 2A is a schematic illustration of one exemplary
embodiment of a casting processing system according to various
aspects of the present invention.
[0015] FIG. 2B is plan view illustrating the transfer of the
castings from the transport system to a processing station.
[0016] FIG. 3 is an end view illustrating the transport of castings
contained with a guided vehicle being conveyed through a processing
station such as a heat treatment unit.
[0017] FIGS. 4A-4B are side elevational views illustrating an
exemplary embodiment of an automatic guided vehicle according to
the principles of the present invention.
[0018] FIG. 5A is an end view illustrating the passage of a guided
vehicle through a processing station, being supported by the
monorail system on the outside of the processing station.
[0019] FIG. 5B is an end view illustrating the passage of a guided
vehicle through a processing station, being supported by a
conveying system mounted within the inner chamber of the processing
station.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Referring now in greater detail to the drawings in which
like numerals refer to like parts throughout the several views,
FIGS. 2A-2B schematically illustrate one exemplary embodiment of an
integrated metal casting processing facility or system 5 including
a series of casting processing stations, such as a pouring station
10, transfer/loading station 11, mold removal 12, trimming station
13, heat treatment station 14, a quench station 16, and cleaning
and aging stations 17 and 18, for processing a series of castings C
according to pre-programmed processing sequences or paths for such
castings. Other, different processing stations, such as for
machining, inspection, storage, and the like, also can be included
in this casting processing system as will be understood by those
skilled in the art. The present invention is directed to a system
for controlling the movement of such castings between the pouring
station and the various downstream casting processing stations
12-18 as needed to treat the castings to achieve desired physical
properties thereof, to enhance the flexibility and efficiency of
manufacture of such castings by maintaining and controlling their
movement between the processing stations needed to treat or process
the castings to achieve desired physical properties therefore,
according to the programmed processing sequences for each casting
or set of castings.
[0021] 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, however, 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.
[0022] As generally illustrated in FIG. 2A, a molten metal or
metallic alloy M typically is poured into a die or mold 19 at the
pouring or casting station 10 for forming a casting C, such as a
cylinder head, engine block, or other, similar cast part. A casting
core 21, generally formed from sand and a binder such as a phenolic
resin or other known binder materials, can be received or placed
within the mold 19 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 materials as is known in the art.
Such molds also 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 materials forming the sand casting cores 21. 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.
[0023] Additionally, the molds may be provided with one or more
riser 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 these openings can remain 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, such as in trimming station 13 as
needed or desired.
[0024] It will be understood that the term "mold" will be used
hereafter to refer generally to all types of molds and/or dies as
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.
[0025] 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 10 for preheating the molds. Typically, the molds
can be 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 processing temperatures to prevent
mold deterioration during pouring and solidification. In such
cases, and where the metal processing temperature should be higher,
a suitable metal temperature control method, such as induction
heating, also may be employed.
[0026] 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 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 arrest or minimize cooling of the
casting prior to its movement into a desired casting processing
station.
[0027] As indicated in FIG. 2A, each of the molds 19 generally can
include side walls 22, an upper wall or top 23, and a lower wall or
bottom 24, which collectively define an internal cavity 26 in which
the molten metal M is received and formed into the casting C. A
pour opening 27 generally is formed in the upper wall or top of
each mold and communicates with the internal cavity for passage of
the molten metal through and into the internal cavity 26 of each
mold. As also indicated in FIG. 2A, the pouring station 10
generally includes a ladle or similar mechanism 28 for pouring the
molten metal M into the molds 19. The pouring station 10 further
can include a conveyor, carousel, or similar conveying mechanism,
that moves one or more molds from a pouring or casting position,
where the molten metal is poured into the molds, to a transfer
point or position at or within the transfer/loading station 11.
Thereafter, the castings can be removed from their molds and
transferred, or transferred while remaining in their molds, by a
robotic arm or other similar transfer mechanism or manipulator,
such as shown at 29 in FIG. 2B, to a transport system 40 for
conveyance to the downstream processing stations or chambers
thereof as indicated at 12-14 in FIG. 2A. 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
solidify into the castings. The castings then are transported to
one or more of the downstream processing stations for further
processing such as, for example, heat treatment, as illustrated in
FIGS. 2A-3.
[0028] It further has been discovered that, as the metal of the
casting is cooled down below its solidification temperature, it
reaches a temperature or range of temperatures referred to herein
as the "process control temperature" or "process critical
temperature," below which the time required to both raise the
castings to their solution heat treatment temperature and perform
the heat treatment thereof 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.
[0029] In one aspect, the process control temperature may be from
about 380.degree. C.-480.degree. C. to upwards of about 600.degree.
C. and as low as about 250.degree. C.-325.degree. C. for castings
made from aluminum or aluminum/copper alloys or similar metals. In
another aspect, the process control temperature maybe from abut
800.degree. C. to about 1300.degree. C. for some iron or iron
alloys. The process control temperature further generally is below
the solution heat treatment temperature for most aluminum/copper
alloys, which typically is from about 40.degree. C.-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.
[0030] When the metal of the castings is within the desired process
control temperature range, the casting typically will be cooled
sufficiently to solidify as 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. or lower, 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. This solidification
temperature will be understood as varying and can be determined as
understood by those skilled in the art based on the formulation of
the metal being cast. However, if the metal of the casting is
permitted to cool below its process control temperature, it has
been found that the time that the casting will need to be exposed
to heat treatment at the desired heat treatment temperature for the
metal of the casting will be increased by more than one minute, and
possibly for at least about three-four additional minutes or more,
for each minute that the metal of the casting 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. 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 as needed to achieve the
desired physical properties for the casting may be increased
significantly.
[0031] 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 at least an additional forty minutes to ensure that
all of the castings are heat treated properly and completely.
[0032] 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, wherein the
castings are moved and/or transitioned (within or apart from their
molds) from the pouring station 10 to and through a
predetermined/programmed series of processing stations, i.e.,
trimming, heat treatment, and then quenching or heat treatment
quenching, cleaning and aging, while arresting cooling of the
molten metal prior to heat treatment thereof at a temperature at or
above the process control temperature of the metal, but below or
equal to the desired heat treatment temperatures thereof to allow
the castings to solidify. Accordingly, various aspects of the
present invention include a system control 35 for monitoring both
the location and/or movement of the castings along the transport
system and the temperature of the castings during such transport to
ensure that the castings are maintained substantially at or above
the process control temperature. Still further, the system control
can be linked to and in control of the various processing stations
so as to control not only the movement and dwell time of the
casting through the processing stations, but also the operation of
these processing stations (e.g., the heat treatment temperature of
the heat treatment station, the application of fluid media for
cleaning, and/or trimming, etc.).
[0033] Additionally, thermocouples or other similar temperature
sensing devices 36 (FIG. 2A) can be placed on or adjacent the
castings, such as at spaced locations along the path of travel of
the castings from the pouring station 10 to the heat treatment
station 12 so as to provide substantially continuous monitoring of
the temperature of the castings. Alternatively, periodic monitoring
of the castings at intervals determined to be sufficiently
frequent, may be used. Such sensing devices may be in communication
with the system control 35 that can be linked to and in control of
one or more heat sources positioned at desired or predetermined
locations along the path(s) of travel of the castings C from the
pouring station 10 to the trimming, mold removal, and/or heat
treatment stations 12-14. One or more heat sources also can be
positioned on or adjacent the robot or transfer mechanism 29 (FIG.
2B) of the transfer/loading station 11 and along the transport
system 40 for applying heat to the castings during transfer of the
castings to the heat treatment station or a chamber thereof.
[0034] The temperature measuring or sensing device(s) and the
operation of the heat source(s) upstream from the heat treatment
station 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 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.
[0035] As indicated in FIGS. 3-5B, the transport system 40 for the
integrated casting processing facility 5 typically will comprise an
overhead gantry or monorail system 41 including a guide track 42
along which a series of guided vehicles 43 are supported for
transport of the castings C along various casting processing
pathways according to their predetermined programmed casting
processing sequences to perform various processing operations
thereon to achieve the desired metallurgical properties of the
castings. This monorail or other conveying system typically will be
designed to accommodate maximum payload ranges of up to four-five
tons, which can be conveyed at speeds upwards of 250-300 feet per
minute. In some applications, greater maximum payloads may be
designed into the system as needed or required, while the
processing speeds further can be varied (i.e., increased or
decreased) as needed to accommodate the efficient transfer and
processing of the different type castings being processed.
[0036] As indicated in FIG. 2A-2B, the guide track 42 of the
monorail system 41 typically includes a series of spur lines,
segments or pathways 44 that diverge or branch off from each other
at a series of junction points 46 (FIG. 2A) generally located at or
adjacent the upstream or downstream ends of the processing stations
12-18. According to the principles of the present invention, the
system control 35 for the casting processing system 5 will monitor
the guided vehicles 43 (FIG. 2B) as they approach the junction
points 46 of the transport system 40 and will direct the guided
vehicles 44 to a next processing station according to the
programmed processing sequence for the castings or sets of castings
contained thereon. The guide track 42 of the monorail system can
include a constant driven chain system such as, for example, a ski
lift type system, utilizing a series of driven chains or belts 47
(FIG. 4B) that are constantly moving along their respective
portions of the guide track, or a walking beam type system for
moving the guided vehicles therealong. Alternatively, the guide
track further can be formed from a metal material through which an
electric current is conducted to help drive each of the guided
vehicles 43 along the guide track.
[0037] With such a constant driven chain type drive system, the
guided vehicles can be releaseably mounted thereto so as to be
engagable and disengagable from the drive chain for transfer of the
vehicles between various segments or pathways of the guide track.
In such an embodiment, the monorail system further will generally
include a drive mechanism such as an electric motor, battery pack,
and one or more drive gears for driving the belt, chains or walking
beams of the guide track segments. Alternatively, in the embodiment
of the guide track for the monorail system that includes a
conductive rail along which an electric current is passed, the
guided vehicles generally will include an inductive type drive
mechanism that is driven therealong by the current passing through
the rail of the guide track. For example, such a conductive rail
conveyance system can include a Siemans Dematic or "RoboLoop".TM.
system or other, similar system as known in the art that generally
can be laid out in straight lines and with curved sections that
typically will be modular for each expansion or reconfiguration
based upon changing needs within the casting processing facility or
system.
[0038] As indicated in FIGS. 3-5B, each of the guided vehicles 43
generally includes an elongated, vertically extending support
section 50 that is attached to and supported from the guide track
42 of the transport system 40 by carrier 51. As shown in FIG. 4A,
the carrier 51 can include a series of rollers or drive wheels 52
and a carrier base 53 on which the vertical support section 50 can
be detachably mounted. The drive wheels are adapted to engage and
roll along the guide track 42 of the transport system 40. In
addition, the carrier base 53 also can have a drive motor or other,
similar drive mechanism 54 for driving the drive wheels 52 to
convey the carrier base on support section 50 along their desired
path or travel. Still further, as indicated in FIG. 4B, for systems
where the monorail 41 of the transport system 40 includes a driven
chain or belt 47, the carrier 51 (FIG. 4A-4B) can include a locking
clamp 55 adapted to releasably engage and disengage the carrier
from a downwardly extending locking projection or arm 56 attached
to the drive chain 47. A locking lever or arm 57 typically is
mounted to the carrier 51 in a position projecting forwardly
therefrom and can be engaged so as to cause the clamping sections
55A/55B of the locking clamp 55 to be pivoted into engagement with
a locking projection 56 of the drive chain 47 and/or disengage from
the locking projection for transfer of the guided vehicle 43 to
another section in the pathway 44 of the guide track 42.
[0039] As further illustrated in FIGS. 4A and 4B, the vertical
support section 50 of each guided vehicle 43 generally includes one
or more support racks 60 having one or more compartments or baskets
61 that project outwardly from the central support section 50, and
are adapted to receive a series of castings C therein. The guided
vehicles 43 further will include one or more identifiers 62 mounted
or applied to one or more of the support racks 60, as indicated at
FIG. 4A, or at one or more desired points along the central support
section 50 of each guided vehicle 43. Each of the identifiers
designates and coordinates a casting or series of castings
contained within one or more racks/baskets of each guided vehicle
with a pre-programmed processing sequence for such casting(s),
e.g., with a desired sequence of processing stations 12-18 (FIG.
2A) and steps needed to achieve the desired physical properties for
such casting(s).
[0040] The identifiers can include visual identifiers such as bar
codes, reflective tags, or alphanumeric identifiers applied to or
formed on the racks or the central support section of each guided
vehicle, which visual identifiers can be read by optical sensors or
detectors 63 (FIG. 4B), such as alphanumerical scanners,
photoelectric detectors, or other, similar detectors. Typically,
one or more detectors will be mounted at selected locations along
the path of travel of the guided vehicles, for example, upstream
from the junction points along the guide track. The detectors
generally will be mounted to positions adapted to read the
identifiers on the guided vehicle and/or racks/baskets thereof.
Alternatively, the identifiers can include infrared or RF tags, or
other wireless transmitters or transceivers that emit wireless
signals that can be monitored by the detectors 63 as the guided
vehicles pass thereby.
[0041] As the identifiers are detected or read by the detectors 63,
the detectors will send a signal indicative of the position of such
monitored/detected guided vehicles, and thus the castings supported
thereon, to the system control 35 (FIG. 2A) for purposes of
tracking the progress of the casting through the processing system
5 of the present invention. In response, the system control can
thereafter automatically direct the guided vehicles to a next
desired processing station (i.e., heat treatment, trimming, or
quenching, etc.) according to the pre-programmed processing
sequence for a particular casting or batch of castings contained on
such a guided vehicle. As a result, the entire guided vehicle, and
thus the entire set or batch of castings supported thereon, can be
transferred or redirected to a next desired processing station
according to its preprogrammed processing sequence.
[0042] In another example embodiment, the racks/baskets containing
the individual castings or batches of castings contained within the
various support racks 60 or the baskets 61 of each of the guided
vehicles can be handed off or transferred directly into a next
desired processing station as needed. For example, the racks 60
themselves can be removably mounted to each of the central support
sections of the guided vehicles 45 and thus can be detached and fed
directly into a processing station, such as the heat treatment
station 14 (FIG. 2A). Additionally, the baskets or the castings
contained therein can be transferred to another guided vehicle or
simply dumped or otherwise transferred to another conveyance
mechanism, such as a basket or rack of another guided vehicle for
transfer to the next processing station for such castings.
[0043] Accordingly, each guided vehicle or basket/rack thereof will
be provided with its own unique identifier associated therewith to
enable precise tracking and control of the movement of the
casting(s) received thereon throughout the casting processing
system/facility. This will further enable enhanced flexibility and
efficiency in the various processing of the castings by
automatically transferring the castings to the processing stations
as required for the processing of the castings to achieve the
desired or necessary physical characteristics thereof.
[0044] As further illustrated in FIGS. 3 and 5A-5B, after being
transferred or directed to a next desired processing station, the
guided vehicles 43 can be conveyed through such a processing
station, for example, the heat treatment station 14, while
remaining connected to and transported by the overhead monorail
system 41 as indicated in FIGS. 3 and 5A. Alternatively, the guided
vehicles can be transferred to separate, stand-alone transport
systems, such as indicated at 70 in FIG. 5B, for transport of the
guided vehicles through such processing stations. Still further,
the castings also can be unloaded into other types of conveying
mechanisms, such as into baskets of a roller hearth, for movement
through the processing stations.
[0045] In operation of the casting processing system 5 (FIG. 2A),
after the molten metal M or metallic alloy has been poured into a
series of the molds or dies and has at least partially solidified
to a degree where the resultant formed castings C will not deform,
the molds or dies with the castings therein generally are removed
from the pouring station by a transfer mechanism. The
castings/molds are initially transferred to the transport/loading
station 11 where they are placed on a rack or basket of a guided
vehicle of a transport system 40, such as an overhead gantry or
monorail conveyor 41, for conveyance of the castings in series or
in batches to various ones of the processing stations according to
the pre-programmed processing sequence or instructions for a
particular casting or set of castings.
[0046] Each guided vehicle, or each rack/basket of each guided
vehicle, generally will have an identifier 62 already applied
thereto prior to being loaded with the castings. Once a particular
casting or set of castings have been loaded on the racks/baskets, a
detector reads the identifier associated therewith and notifies the
system control that the casting or set of castings just released
from the pouring station has been loaded on a guided vehicle or a
particular rack having that identifier. The system control will
then match the programmed processing sequence for that detected
casting or batch of castings with that identifier for tracking
through the facility.
[0047] After the castings have been loaded into the racks of the
guided vehicles 43 (FIG. 2B), a scanner or tracking system is used
to track individual castings/molds and/or sets thereof and their
location in the rack. The movement of each of the guided vehicles
of the monorail system also can be recorded, tracked, and
controlled by the system control. The rack system of each guided
vehicle also may have numerous identified locations, thereby
allowing a single guided vehicle to carry numerous castings or
components that will be directed to a variety of different
processing stations. The system control monitors the status of each
of the guided vehicles and/or racks thereof and is programmed with
the sequence(s) for moving the castings into and through
predetermined ones of the processing station for the casting or
components. Once the system control determines the position and
necessary pathway for processing the castings or components, it
directs their guided vehicles to carry them to their necessary
processing station(s) according to their programmed processing
sequence(s).
[0048] The system control additionally monitors all the processing
stations as the castings are moved into and out of required
processing stations. If the castings have an exterior mold or
interior cores, the system control initially may direct the guided
vehicles therefore to a pulse wave demolding or decoring station
where at least a portion of the mold and/or core may be removed or
separated from the casting. An example of such demolding and
decoring that can be utilized with the present invention is
illustrated in U.S. Pat. No. 6,622,775, the disclosure of which is
also incorporated herein in its entirety by this reference. The
molds and cores may be removed by physically impinging with a fluid
or by sound, or the casting may be physically shaken or vibrated to
break up the sand core and remove the sand.
[0049] An alternative processing path or sequence can include
directing the castings to the trimming station for the removal or
unblocking of orifices before the demolding station. For instance,
the "trimming" system may be used to penetrate and cut the
blockages from the openings of the castings using external
pressure. Various other types of mechanical methods including
punching or trimming devices as known in the art may be used,
including a laser, a water jet, a physical or mechanical cutter,
such as a milling machine, drill or boring device, a saw device, or
a punch press system with piercing/upsetting dies to cut or
otherwise physically penetrate the blockage. Still further, such a
trimming system may be controlled by the system control to employ
variable pressure, volume and/or temperature of the fluids, for
example water, air, thermal oils, sand or other particulate media,
etc., to cut or trim the blockage and expose the core according to
the programmed processing sequence for the castings. The trimming
means may also be used to remove the feed gates and/or risers which
are formed during the forming of the castings. The trimming and/or
demolding processes may be started and/or completed while the
temperature of the castings is maintained at or above the "Process
Critical Temperature" to aid in the decreasing of the actual heat
treatment time period for heat treating the castings.
[0050] After substantial decoring and demolding, the system control
generally will direct the guided vehicles with the castings therein
to a next programmed processing station, such as solution heat
treatment station 14 (FIG. 2A) to strengthen or harden the casting
or to relieve internal stresses, or to quenching, cleaning, etc.
During heat treatment, the cast alloy or metal is heated to a
suitable temperature, held at that temperature long enough to allow
a certain constituent to enter into solid solution, and then cooled
rapidly to hold that constituent in solution. The heat treatment
station generally includes a heat treatment furnace, typically a
gas fired furnace or heated by a commonly allowable means, and
generally includes a series of treatment zones or chambers for heat
treating each casting and removal and reclamation of the sand
material of the sand cores. Such heat treatment zones may include
various types of heating environments such as conduction zones,
including the use of fluidized beds, and convection zones or other
commercially viable systems known in the art, such as using heated
air flow. The number of treatment zones also may vary as needed or
required for a particular application to remove the sand cores.
[0051] The residence or dwell time of the castings within the heat
treatment station, or each zone thereof, generally will be a
function of the time needed for heat treating the castings to a
desired level, and can be controlled by the system control
according to the programmed processing sequence for each batch of
castings associated with that particular identifier to achieve the
desired heat treatment properties. It is also possible to partially
age the castings within the heat treatment station if desired. The
heat treatment station also can be designed so that the gantry or
monorail conveyor 41 will be able to convey the castings through
the heat treatment station without requiring unloading or transfer
of the guided vehicles to a separate conveying mechanism, as
indicated in FIG. 5A. Alternatively, as indicated in FIG. 5B, the
racks of the guided vehicles, or simply the castings therein, can
be transferred to a separate conveying or transport system 70
contained within the heat treatment or other processing station,
with the racks and/or castings thereafter being loaded on a
downstream guided vehicle for transport to another processing
station.
[0052] Examples of a heat treatment furnace or system in which heat
treatment of castings is carried out in conjunction with the
removal of the sand cores from the castings, and potentially the
reclamation of the sand from the sand cores of the castings, are
provided in U.S. Pat. Nos. 5,294,094; 5,565,046; and 5,738,162, the
disclosures of which are incorporated herein in their entireties by
this reference. A further example of equipment for the heat
treatment of metal castings and in-furnace mold and sand core
removal and sand reclamation that can be utilized with the present
invention is illustrated in U.S. Pat. No. 6,217,317, the disclosure
of which is also incorporated herein in its entirety by this
reference.
[0053] According to one aspect of the present invention illustrated
in FIG. 2A, after the heat treatment is complete, each casting can
be transferred from the heat treatment station to a next station,
such as a cleaning station via controlled movement of their guided
vehicles by the system control, or can be individually loaded into
the cleaning station by a robot or other automated loading means.
For cleaning, the castings will be placed into a chamber having
nozzles positioned around the periphery of the casting. One or more
nozzles may be positioned in direct alignment with the open
orifices. Additionally, one or more nozzles may be inserted into
the open orifices. The nozzles then direct an air, water, oil or
other media jet at the orifices to assist with removal of the
cores. During the cleaning process, some areas of the castings may
be slightly quenched; however, any temperature change is likely
minimal. After the cleaning process is complete, the castings may
then be transferred to an aging oven.
[0054] According to yet another aspect of the present invention
depicted in FIG. 2A, the castings may be transferred to a quenching
station after heat treatment or after cleaning. The quenching
process provides a high volume/pressure of fluid media (water, air,
steam, oil, etc.) to the castings via the cleared orifices or
otherwise. The quenching process may utilize a quench tank or
reservoir filled with a cooling fluid, such as water or other known
media material, in which each casting or batch of castings are
immersed for cooling and quenching. The quench tank or reservoir
generally is designed to accommodate various sizes and types of
castings being formed, the specific heat of the metal or metal
alloy, and the temperatures to which each casting has been heated.
The quench time and temperature generally are controlled to achieve
the desired resulting mechanical and physical properties of the
castings. For example, the system control can control the quench
time and temperature of the quench media applied according to the
programmed processing sequence for each identified casting or group
of castings. In some instances, the quench station may be
maintained at about 120.degree. F. to about 200.degree. F. As
above, the casting may then be transferred to an aging oven
immediately or at a later time dependent by the required process
for the specific component.
[0055] Often, the quenching media accumulates traces of sand from
the castings. The sand then re-deposits on the castings. To further
remove any traces of sand on or in the castings, the castings may
be transferred to a cleaning station. As described above, the
cleaning process subjects the castings to a variable volume,
pressure and temperature of a media stream of air, water, oil, or
steam. Where air is used to clean the castings, the cleaning
process may further quench the castings. After cleaning the
castings, the castings may then be placed into an aging oven if
desired. Both the cleaning and or quenching station will be
designed so that the guided vehicles will be able to convey the
castings through the stationing without any type of unloading or
load mechanism. A further example of decoring and cleaning can be
utilized with the present invention is illustrated in U.S. Pat. No.
6,910,522 the disclosure of which is also incorporated herein in
its entirety by this reference. After cleaning and quenching, the
system control can then monitor and direct each guided vehicle to
deliver the castings therein to a machining, inspection or storage
station where further necessary processing according to the
programmed processing sequence therefore can be completed.
[0056] Throughout the manufacturing process the system control
commands and controls movement of the guided vehicles to each of
their assigned processing stations or tasks, such as presenting a
casting to a particular processing/machining station, removing the
casting from each such processing station, and conveying casting(s)
between required processing stations, etc. Each identifier of each
guided vehicle also can include a processor or controller including
an infrared or RF transceiver or other wireless communication
device for communicating with the main system control located
remotely from the monorail system, so as to actively send
positional and status information from each guided vehicle to the
main system control and receiving task commands from the main
system control on a regular timely interval.
[0057] Additionally, the guided vehicles also may be adapted to
simply deliver individual basket type of carriers to and from the
various processing stations, as well as be directed to transport
waste materials or finished castings back to a designated area.
According to yet another aspect of the present invention depicted
in, the rack system or baskets of the guided vehicles can
incorporate saddles or locating pins to assure proper orientation
of the casting or components during the processing station
procedures.
[0058] The present invention is directed to a system for lowering
the overall cost, labor, energy for the manufacturing of castings
by removing direct human contact and using flexible manufacturing
principles. Since only minimal human contact is required, human
errors and safety concerns will be lowered or eliminated making the
process more efficient and safer. Flexible manufacturing also
allows a manufacturing facility to produce different product lines
or components during identical time periods without modifying the
manufacturing stations. A logic computer program can be created for
the system control to adjust or maintain different processing times
for the various different castings or components by modifying their
delivery to the required station by the guided vehicles; thereby
increasing the overall efficiency of facility. For an example, if
the castings have a shorter or longer required heat treatment
processing requirement, then the system controller would adjust the
delivery time of the guided vehicle(s) for the relevant
castings/components to the heat treatment station and the dwell
time within the station to assure optional efficiency for that
particular station. Furthermore additional queuing or thermal
arresting chambers also may be required or utilized on a spur
portion of the gantry or monorail line to assure efficiency at the
processing stations. Utilizing an adaptive flexible and
"just-in-time system" will allow the manufacture to produce a
variety of different components at the identical time and minimize
storage and stock inventory.
[0059] 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. 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 thus 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.
* * * * *