Note: Descriptions are shown in the official language in which they were submitted.
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METHODS AND SYSTEM FOR MANUFACTURING CASTINGS UTILIZING
AN AUTOMATED FLEXIBLE MANUFACTURING SYSTEM
Cross-Reference to Related Applications
The present patent application is a formalization of previously filed, co-
pending United States provisional patent application serial no. 60/813,938,
filed June
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 119(e)(1) and 37 CFR
1.78(a)(4) and (a)(5). The specification and drawings of the provisional
patent
application are specifically incorporated herein by reference.
Back2round of the Invention
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.
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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.
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.
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
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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.
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
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
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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.
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.
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
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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.
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.
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.
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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
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.
Fig. 2A is a schematic illustration of one exemplary embodiment of a casting
processing system according to various aspects of the present invention.
Fig. 2B is plan view illustrating the transfer of the castings from the
transport
system to a processing station.
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.
Figs. 4A - 4B are side elevational views illustrating an exemplary embodiment
of an automatic guided vehicle according to the principles of the present
invention.
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.
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.
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Detailed Description of the Invention
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.
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
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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.
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.
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
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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.
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.
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 C to about 600 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 C to about 600 C.
Additionally, some mold types require lower processing temperatures to prevent
mold
deterioration during pouring and solidification. In such cases, and where the
metal
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processing temperature should be higher, a suitable metal temperature control
method,
such as induction heating, also may be employed.
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 C to about 300
C, to
cool the casting and cause the casting to solidify. A high temperature thermal
oil, for
example, heated to from about 500 C to about 550 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.
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
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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.
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
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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.
In one aspect, the process control temperature may be from about 380 C -
480 C to upwards of about 600 C and as low as about 250 C - 325 C for castings
made from aluminum or aluminum/copper alloys or similar metals. In another
aspect,
the process control temperature maybe from abut 800 C to about 1300 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 400 C - 427 C to about 495 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.
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 C - 425 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
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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 C to about 495 C for aluminum/copper alloys, or
from
about 510 C to about 570 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.
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.
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
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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.).
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
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castings during transfer of the castings to the heat treatment station or a
chamber
thereof.
The temperature measuring or sensing device(s)--and--the-oper-ation-o-f-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.
As indicated in Figs. 3 - 513, 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
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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.
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.
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
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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.
As indicated in Figs. 3 - 513, 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
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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.
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).
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
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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.
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.
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
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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.
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.
As further illustrated in Figs. 3 and 5A - 513, 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.
3and 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.
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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.
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.
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
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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).
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. Nos. 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.
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
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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.
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
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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.
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.
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
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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.
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.
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
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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 F to about 200 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.
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. Nos. 6,910,522 the disclosure of
which is
also incorporated herein in its entirety by this reference. After cleaning and
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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.
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.
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.
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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.
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
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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.
29
