U.S. patent application number 13/125685 was filed with the patent office on 2011-12-15 for automated system for improved cooling of aluminum castings in sand molds.
Invention is credited to Mario Alberto Leon-Quezada, Jose Augusto Martinez-Ruiz, Ramiro Montero-Cantu, Gerardo Salinas-Pena.
Application Number | 20110303385 13/125685 |
Document ID | / |
Family ID | 40568156 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110303385 |
Kind Code |
A1 |
Salinas-Pena; Gerardo ; et
al. |
December 15, 2011 |
AUTOMATED SYSTEM FOR IMPROVED COOLING OF ALUMINUM CASTINGS IN SAND
MOLDS
Abstract
An improved and efficient method and apparatus for convective
cooling of cast sand molds containing molten metal, utilizing
vertically-arrayed cooling stations (preferably arranged on a
plurality of shelves inside a housing enclosure for temporarily
storing said sand molds during their cooling from a molten
temperature level to a lower solidification temperature. A draft of
cooling air is circulated through said stations in said housing
whereby the time for solidifying the molten metal in said cast sand
molds is reduced as compared with passive air cooling of said
molds. Robot means are provided for moving hot sand molds from a
feeding port in said housing to said shelves and for moving cooled
sand molds from said shelves to a delivery port in said housing.
The robot means is programmed so that the time period of each mold
is maintained within said housing according to the individual time
required for the solidification of the metal in such individual
mold (based on empirical data for typical solidification required
for the given individual cast sand mold package or based on other
appropriate discernible physical property attributable to achieved
solidification).
Inventors: |
Salinas-Pena; Gerardo;
(Nuevo Leon, MX) ; Leon-Quezada; Mario Alberto;
(Nuevo Leon, MX) ; Martinez-Ruiz; Jose Augusto;
(Nuevo Leon, MX) ; Montero-Cantu; Ramiro; (Nuevo
Leon, MX) |
Family ID: |
40568156 |
Appl. No.: |
13/125685 |
Filed: |
October 23, 2008 |
PCT Filed: |
October 23, 2008 |
PCT NO: |
PCT/IB2008/002841 |
371 Date: |
September 2, 2011 |
Current U.S.
Class: |
164/458 ;
164/124; 164/270.1; 164/348; 164/76.1 |
Current CPC
Class: |
B22D 30/00 20130101;
B22D 47/00 20130101; B22D 45/00 20130101 |
Class at
Publication: |
164/458 ;
164/348; 164/270.1; 164/124; 164/76.1 |
International
Class: |
B22D 46/00 20060101
B22D046/00; B22C 9/00 20060101 B22C009/00; B22C 23/00 20060101
B22C023/00; B22D 27/04 20060101 B22D027/04 |
Claims
1. An apparatus for convective cooling of cast sand molds
containing molten metal, comprising: an enclosure housing having a
roof and side wall; a plurality of vertically arrayed stations
contained inside said housing for temporarily storing said cast
sand molds for their cooling from a molten temperature level to a
lower solidification temperature level; means for actively
producing a draft of cooling air circulating through said stations
and around said molds therein from at least one inlet cooling air
source in said housing to at least one hot air outlet from said
housing whereby the cooling of said cast sand molds is accelerated
and the solidification time is reduced as compared with passive air
cooling of said cast sand molds; and programmable robot means for
moving hot cast sand molds from a feeding port in said housing each
to a respective station and for moving cooled cast sand molds
containing solidified metal from said respective stations to a
delivery port in said housing.
2. An apparatus according to claim 1, wherein said robot means is
programmable for introducing and then for withdrawing said molds
after a given time interval as required for the solidification of
said metal therein.
3. An apparatus according to claim 2, further comprising conveying
means for introducing said cast molds containing molten metal into
said housing.
4. An apparatus according to claim 3, further comprising conveying
means for withdrawing cooled molds containing adequately solidified
metal from said housing.
5. An apparatus according to claim 4, wherein there is a single
inlet for said cooling air source which is located at a central
part in the roof of said housing.
6. An apparatus according to claim 5, wherein said means for
actively producing a draft of cooling air is a blowing means in
said single inlet located above said stations.
7. An apparatus according to claim 6, wherein there are a plurality
of hot air outlets located spaced at the outer periphery of the
roof of said housing.
8. An apparatus according to claim 7, wherein there are a plurality
of inlets for said cooling air source located at the lower part of
said housing.
9. An apparatus according to claim 8, wherein said means for
actively producing a draft of cooling air includes extraction means
in the form of fans each in a plurality of hot air outlets located
spaced at the outer periphery of the roof of said housing and above
said stations.
10. An apparatus according to claim 9, wherein said extraction
means is structured to withdraw hot air through the roof of said
housing.
11. An apparatus according to claim 1, wherein said vertically
arrayed stations are shelves disposed in a linear arrangement and
said robot means travel alongside said shelves.
12. An apparatus according to claim 1, where said housing has a
cylindrical shape; and said robot means is located anchored in the
center of said housing, and said vertically arrayed stations are a
single set of shelving circularly arranged around said robot
means.
13. An apparatus according to claim 12, where said vertically
arrayed stations are a single set of shelving arranged in a
semi-circle around said robot means.
14. An apparatus according to claim 13, further comprising
scrubbing means for cleaning any noxious gases emanating from said
cast sand molding within said housing.
15. A method for convective cooling of cast sand molds containing
molten metal, comprising: feeding cast sand molds containing molten
metal into a housing containing a vertical array of closely spaced
cooling stations; robotically placing individual cast sand molds
each into a respective cooling station; actively circulating
cooling air into said housing from at least one cooling air source,
through said stations and around said cast sand molds situated
therein, and on out of said housing through at least one hot air
discharge, whereby the cooling of said cast sand molds is
accelerated and the solidification time is reduced as compared with
passive air cooling of said cast sand molds; robotically removing
individual cast sand molds upon solidification from its respective
cooling station; said robotic placement and removal being
controlled by applied programming to control the time spent by each
cast sand mold within said housing to that needed to achieve
solidification of the metal sufficient to permit proper handling in
subsequent processing steps; removing the resulting cast sand molds
from said housing.
16. The method of claim 15, wherein the cast sand molds containing
molten metal are all essentially the same and the robotic
programming retains each such mold in its cooling station in the
housing for a time determined to be minimally required for adequate
solidification of the molten metal and is thereafter promptly
removed from the housing.
17. The method of claim 15, further comprising monitoring in each
cooling station any cast sand mold present therein to sense the
presence of an intrinsic attribute of the metal present only when
adequately solidified and promptly removing such mold from the
station and the housing upon sensing such an intrinsic attribute,
irrespective of when such mold was introduced into the housing
relative to when the other molds within the housing.
18. The method of claim 17, wherein the intrinsic attribute is a
given surface temperature of the mold, which temperature has been
determined to be indicative of adequate solidification of the metal
within the cast mold.
19. The method of claim 15, further comprising cleaning any noxious
gases emanating from any cast sand moldings within said
housing.
20. The method of claim 18, further comprising cleaning any noxious
gases emanating from any cast sand moldings within said housing.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of foundries and
metal casting. More particularly, the present invention teaches an
improved automated and efficient system for cooling sand mold
packages filled with molten metal by air convection cooling
minimizing the space necessary for cooling down large numbers of
sand mold packages with the additional advantages of improved
quality of the castings and savings in capital and in operational
costs.
BACKGROUND OF THE INVENTION
[0002] In the metal casting industry, molds containing molten metal
must be cooled down sufficiently to solidify the metal before
passing the casting on to the next steps in the process; such as
extracting the casting from the mold and then eliminating the sand
cores that were utilized to shape the piece to the desired
geometry. In some processes using permanent molds, the cooling of
the casting is accelerated by circulating a cooling fluid through
certain metallic portions of the mold. The productivity of the
foundry is tied to the time needed for the casting to reach the
solid state sufficiently so that it can be extracted out of the
mold; and then successively filling again said mold for casting the
next piece. The time needed for cooling down the casting is longer
if the mold is made of sand, since the sand mold package does not
have the permanent mold's desirable heat-transfer properties for a
rapid cooling, and therefore these sand molds require a longer time
for cooling.
[0003] The filling of the sand molds with molten metal is done
quickly, on the order of about 20 to 50 seconds. Thus, the cooling
time is the principal concern. According to long-established
practices, it has been necessary to provide a substantial amount of
plant space for storing the hot sand packages during their cooling.
The sand molds containing molten metal require sufficient spacing
for adequate air convection cooling. This practice requires a large
footprint area in the foundry and may become a critical factor for
increasing the productivity of the foundry.
[0004] One of the other drawbacks of the usual current practice
concerns liberation of noxious fumes and vapors from the sand molds
and their cores caused by the heating of the resins used as binders
of the sand molds, which causes odors and contamination of the
plant area where the molds and their castings are cooled down.
[0005] U.S. Pat. No. 5,771,956 to Kimura only partially addresses
the problem in the mass production of castings of a long felt need
for more efficient handling during cooling of molds containing
molten metal. Kimura describes apparatus having an array of cooling
lines comprising several parallel rail lines horizontally arranged
to accommodate wheeled mold carriers. This system has the
disadvantage of still requiring a large plant space. Furthermore,
Kimura is mute regarding the problems and solutions relative to the
emission of contaminating fumes and vapors, as well as relative to
the need for an increase in productivity by actively reducing the
time required for solidifying the molten castings.
[0006] This patent is incorporated herein by reference.
OBJECTIVES OF THE INVENTION
[0007] The present invention overcomes the disadvantages of the
current systems and provides a cooling system for sand molds
containing molten metal providing a number of advantages.
[0008] It is therefore an object of the present invention to
provide an improved cooling system for sand molds containing molten
metal which increases the productivity of a foundry.
[0009] It is another object of the present invention to provide an
improved and efficient cooling system for sand molds containing
molten metal which advantageously controls the fumes and odors
emitted by the hot sand molds and cores producing a cleaner
environment in the foundry.
[0010] It is still another object of the invention to provide an
improved and efficient cooling system for sand molds containing
molten metal which may be operated by automatic programmed robots
and equipment.
SUMMARY OF THE INVENTION
[0011] The above objects of the invention are generally achieved by
providing an apparatus for convective cooling of cast sand molds
containing molten metal, comprising: an enclosure housing having a
roof and side wall; a plurality of vertically arrayed stations
contained inside said housing for temporarily storing said cast
sand molds for their cooling from a molten temperature level to a
lower solidification temperature level; means for actively
producing a draft of cooling air circulating through said stations
and around said molds therein from at least one inlet cooling air
source in said housing to at least one hot air outlet from said
housing whereby the cooling of said cast sand molds is accelerated
and the solidification time is reduced as compared with passive air
cooling of said cast sand molds; and programmable robot means for
moving hot cast sand molds from a feeding port in said housing each
to a respective station and for moving cooled cast sand molds
containing solidified metal from said respective stations to a
delivery port in said housing.
[0012] The above objects of the invention are also generally
achieved by providing a method for convective cooling of cast sand
molds containing molten metal, comprising: feeding cast sand molds
containing molten metal into a housing containing a vertical array
of closely spaced cooling stations; robotically placing individual
cast sand molds each into a respective cooling station; actively
circulating cooling air into said housing from at least one cooling
air source, through said stations and around said cast sand molds
situated therein, and on out of said housing through at least one
hot air discharge, whereby the cooling of said cast sand molds is
accelerated and the solidification time is reduced as compared with
passive air cooling of said cast sand molds; robotically removing
individual cast sand molds upon solidification from its respective
cooling station; said robotic placement and removal being
controlled by applied programming to control the time spent by each
cast sand mold within said housing to that needed to achieve
solidification of the metal sufficient to permit proper handling in
subsequent processing steps; and removing the resulting cast sand
molds from said housing.
[0013] The present invention advantageously provides an improved
and efficient cooling system for sand molds containing molten metal
which utilizes vertical space for storing the hot sand molds and
thus saves plant area decreasing the capital and operation costs of
the casting facility.
[0014] The present invention further provides an improved and
efficient cooling system for sand molds containing molten metal
wherein the sand molds are in contact with a stream of air
improving the convection heat transfer and making it uniform
through the molds and favorably modifying the cooling process of
the castings producing pieces with better quality and mechanical
properties avoiding the concentration of residual stresses.
[0015] Applicants have found that the apparatus of the present
invention not only cools more rapidly, but unexpectedly also
results in a decrease in residual stresses in the castings that
otherwise may occur due to uneven heat-transfer areas that may
develop in the molds, especially for molds with thin walled
castings.
[0016] It is also a further advantage of the present invention
that, not only is space saved in the foundry, but also by confining
the forced air convection within an enclosed space, the fumes and
vapors produced by the hot resin binder of molds and cores can be
controlled and eliminated, providing a cleaner ambient atmosphere
in the area.
[0017] Furthermore, the applicants have also found that the forced
convection cooling of the sand packages improves the overall
quality and mechanical properties of the castings by increasing the
cooling rate and therefore favorably affecting the solidifying
process of the castings.
[0018] Other objects and advantages of the invention will be later
pointed out, or will be evident to those skilled in the art from
the following specification and the attached figures describing
some preferred embodiments of said invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic side sectional view of a preferred,
circular, embodiment of the cooling system according to the present
invention.
[0020] FIG. 2 is a schematic plan view of the cooling system of
FIG. 1.
[0021] FIG. 3 is a schematic side sectional view of another
preferred, linear, embodiment of the cooling system according to
the present invention.
[0022] FIG. 4 is a schematic plan view of the cooling system of
FIG. 3.
[0023] FIG. 5 is a flow chart showing some essential steps of the
program controlling the robot for the automatic operation of the
cooling system.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS THE PRESENT
INVENTION
[0024] A preferred embodiment of the invention will be described as
applied to the cooling of sand molds containing aluminum alloys for
manufacturing automotive motor parts, e.g. cylinder engine blocks
and engine cylinder heads.
[0025] Referring to FIGS. 1 and 2, there is shown an apparatus for
improved cooling of aluminum castings in sand molds comprising a
cylindrical housing 10 containing a plurality of vertical shelves
12 which are distributed around at least a portion of the inside of
the circular side wall 11 wall of said housing 10 for the purpose
of storing sand molds 14 in a cooling environment, while the
castings are solidifying. In the illustrated embodiment, each shelf
in each unit of the vertical shelving 12 constitutes a single
cooling station 15.
[0026] The hot newly cast sand molds containing molten metal 14 are
introduced through a sand mold inlet port 16 via conveying feed
means 18. From there, the robot 20 uses its arm 21 with clamp 23
(shown in dotted outline in FIG. 2) to successively pick up each
cast sand mold 14 and, as shown in full outline in the FIG. 2,
delivers such mold to a vacant space in said shelves 12 (which
space serves as a cooling station 15).
[0027] Note that while the position of robotic arm 21 as shown in
full outline is the same in both Figures; this arm 21 where shown
in dotted outline is depicted differently. In FIG. 1, the robotic
arm 21 as shown in dotted outline, in contrast to FIG. 2, is not
picking up from port 16, but instead is shown delivering the mold
to a differently-located cooling station 15.
[0028] Cold air 22 is introduced from a cooling air source inlet 24
by blowing means 26 and circulates within said housing 10 cooling
said molds 14 on shelves 12.
[0029] Cold air 22 may also be introduced into said housing 10
through a plurality of air inlets 28 positioned at the bottom of
the housing side wall 11.
[0030] Hot air 30 is withdrawn from said housing 10 by extraction
means such as fan(s) 32 operating through one or more air outlets
34 located, for example, at the top of said housing 10. The hot air
extraction by means 32 can be sufficient to draw in the cold air
through the air inlets 28. Here the means 32 is shown in the form
of a plurality of fans.
[0031] As an aid in the control and elimination of the fumes and
vapors produced by the hot resin binder of molds and cores, which
have already been confined within the housing 10 and withdrawn
therefrom through the outlets 34, such outlets 34 preferably feed
into an optional gas scrubber 35, so that scrubbed air 37 can be
vented, thus providing a cleaner ambient atmosphere in the casting
foundry area. Robot 20 is programmed to allow sufficient time for
each sand mold 14 to cool down and have its contents solidified
optimizing the productivity of the cooling system.
[0032] The program of robot 20 allows an individualized time
allocation for each sand mold 14 according to its heat transfer
requirements.
[0033] Robot 20 may also be programmed for acting in response not
only to a predetermined time period needed for the solidification
of the molten metal in a given mold but also may be programmed for
acting in response to an intrinsic attribute of the metal present
in the mold indicating when said metal is adequately solidified.
For example, a suitable temperature sensor may be located in each
shelf which may send a signal to the controller of robot 20
triggering the operation of the robot for removing the mold from
its shelf and placed on the conveying means 36 for its further
processing. Other suitable temperature sensors may be used, for
example infrared thermometers mounted on each shelf, or attached to
the traveling robot. Also, other properties undergoing changes if
sensed or measured when metal passes from the molten state to solid
state may be utilized for automating the cooling system operation
and therefore increasing its productivity.
[0034] The vertical arrangement of shelves 12 permits handling and
cooling of more sand molds 14 in a smaller footprint, decreasing
the capital costs for production expansions in foundries.
[0035] This invention keeps sand molds 14 static during the whole
cooling process reducing capital and operation costs as compared
with the cooling systems that are based on conveyors, as for
example described in Kimura.
[0036] After solidification of the metal, robot 20 removes the
cooled sand molds 14 from shelves 12 and places them on a conveying
discharge means 36 which takes the cooled sand molds 14 through a
sand mold outlet 38 for further processing. In another embodiment
of the invention a single conveying means passing across said
housing 10 may be used both for introducing and withdrawing sand
molds 14.
[0037] Referring now to FIGS. 3 and 4 where same numerals designate
equivalent elements shown in FIGS. 1 and 2, enclosure housing 10
has a rectangular shape and a plurality of shelves 12 are
vertically arranged in a linear lay-out. Robot 20 is programmed to
move sand molds containing molten metal 14 from conveying means 18
to a vacant space in said shelves 12. After cooling and
solidification of the metal, robot 20 removes the cooled sand molds
14 from shelves 12 and places them on conveying means 36 which
takes the molds out of the housing 10 for further processing. Robot
20 travels alongside shelves 12 by rolling over rails 25 in a
manner known in the art and can move sand molds 14 to and from
shelves 12, one in front of the other. Robot 20 may also travel
suspended from overhead rails (not shown) instead of rolling or
sliding over ground-level rails, and may serve more than two
cooling stations arranged in a variety of geometrical arrangements
as may best fit a particular plant lay-out.
[0038] Referring to FIG. 5, robot 20 may follow the sequential
steps shown in the diagram for automating the operation of the
cooling system from the moment the sand molds 14 are picked by
robot 20 from inlet conveyor 18 up to the moment when the robot 20
removes the cooled sand mold 14 from its shelf 12 and places it on
outlet conveyor 36.
[0039] According to one of the preferred embodiments of the
invention, robot 20 identifies the sand mold 14 with molten metal
at inlet conveyor 18 and identifies a vacant shelf 12 for storing
said mold 14. Robot 20 sets the initial values of cooling time or
solidification indicator and reads actual values of cooling time or
other solidification indicator of a mold 14 and determines whether
said value has reached a predetermined setting.
[0040] Robot 20 then removes sand mold 14 from its shelf 12 and
places it on outlet conveyor 36. Robot 20 identifies the now empty
shelf as being vacant and repeats the program.
[0041] It is of course to be understood that the above
specification is illustrative only and that the described
embodiments are given for illustration and not for limitation, and
that numerous modifications may be made to these embodiments
without departing from the scope and spirit of the invention, which
is limited only by the scope of the following claims.
[0042] For example, the cylindrical housing 10 as illustrated in
FIG. 2 could be larger; so that shelving 12 could be ranged along
the inner side of the side wall 11 of housing 10 on both sides of
the conveying means 18 & 36 (which means 18 & 36 in turn
are aligned with a diameter of housing 10, and with robot means 20
being positioned between the ends of said conveying means 18 &
36). Also, the shape of the housing 10 need not be strictly
cylindrical or linear and may instead take any form that best suits
the robot means 20, including among other possibilities, a
non-linear layout where the robot 20 may travel alongside the
shelves and between the sand mold inlet 16 and sand mold outlet 38.
Other variations may involve the number of air blowing 26 and air
extracting 32 means used. These may be selected in number,
orientation, and capacity according to the specific design of any
particular application of this invention (including choosing one to
the exclusion of the other).
* * * * *