Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR
M~KING FOUNDRY MOLDS
Field of the Invention
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This invention relates to an apparatus for making
foundry molds by compacting foundry sand about a pattern.
The invention additionally relates to a method of forming
such molds through the compaction of foundry sand about
a pattern.
Bac~s~Kd of~ the Invention
Over the years, many different methods and appa-
ratus have been adopted in the age old process of forming
metal in a desired shape by melting and casting the metal
in a mold. In a usual case, the mold is formed using
patterns about which sand and a binder .re packed.~ The
packing may be performed in a variety of ways and various
techniques have evolved.
For example,ino~e currently available foundry mold
forming apparatus known as a Herman Moldmaster, provision
is made for lining up a flask containing foundry sand
and binder as well as a pattern with a pIatenhaving a
plurality of downwardly projecting squeeze or compacting
heads which are advanced under the influence of fluid
under pressure into the flask for pressing the sand and
binder around the pattern. After the desired compaction
is achieved, the compacting heads are withdrawn and the
flask moved to the next sta~e in the foundry process. Al-
though such a machine is very efficient and generally ac-
ceptable, there are certain patterns that have shapes and/
or configurations that are not fully susceptible to com-
plete ramming due to the squeeze or compressing effectwith the result that less than fully rammed flasks are
produced. Frequently, such flasks may be rejected, or
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if the flas~c is used in the process, an inferior casting may
result. Furthermore, the need for pressurized fluid and
operators responsive thereto for driving the compacting heads
results in a relatively complex, and thus, expensive,
apparatus.
In my Canadian application Serial No. 380,611 now
Canadian patent No. 1,177,221 and entitled "Vibratory Method
for Packiny Foundry Sand into a Pattern Prior to the Pouring
of Molten Metal", there is described methods and apparatus
which may be employed to obviate the problems encountered
in prior art methods and apparatus in causing sand and binder
to enter and compact within the unusual shapes of complex
patterns to avoid the difficulties encountered with non-fully
rammed flasks. While the method and apparatus disclosed in
my Canadian patent is considered to work well for its intended
purpose, occasionally there arises a need for greater
compaction than can be provided by the vibratory system therein
disclosed alone~
Consequently, there has been proposed apparatus which
provides for compaction of foundry sand about a pattern
contained in a flask utilizing both vibratory motion and fluid
pressurized compacting. Again, such system works extremely
well for its intended purpose but the naed for compacting
head operators and a relatively large source of pressure fluid
for such operators increases the complexity of the apparatus
and again, the expense thereof.
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The present invention is directed to overcoming
one or more of the above problems.
Summary of the Invention
It is the principai object o~ the invention to
5 provide a new and improved method and apparatus for
making foundry molds. More speci~ically, it is an
object of the invention to provide a simple apparatus
that provides for compaction of sand in a foundry ~lask
containing a pattern through the use of vibratory motion
and a non-vibratory compacting force that is inexpensive
in cost. It is also an object o~ the invention to pro-
vide a simple and inexpensive method o~ compacting sand
in a flask containin~ a pattern throug~ the use of vibra-
tory motion and a non-vibratory force.
~n exemplary embodiment o~ an apparatus made ac-
cording to the invention achieves the foregoin~ objects
in a structure including a base having means de~ining a
flask receiving station. Means are disposed on the base
for vibrating a flask disposed in the station in at
least a vertical direction. There are provided a plurality
o~ vertically moving compacting heads of substantial mass
and means for lowering the heads into the station and
allowing relative vertical movement between the heads
while they are in the station without applying a downward-
ly directed force other than gravity thereto.
Consequently, the vibratory ~orce provides compaction
as does the force of gravity actin~ through the heads.
A pressure source, and the cost o~ providing the same along
with operators responsive thereto are eliminated.
In a preferred embodiment, the lowerin~ means
include a means mounting the heads for movement into and
out of the station and ~or movement relati~e to each
other in a generally vertical direction with the sole
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downward force acting upon the heads being that ofgravity. Preferably, each of the heads has a lost
motion connection to the mounting means. A powered
actuatox for raising and lowering the mounting means
may also be provided. The powered actuator, the mounting
means and the lost motion connections are constructed and
arranged so as to be incapable of exerting a downward force
on the heads.
A preferred embodiment of a method made according
to the invention includes the steps of placing a pattern
in a mold 1ask, filling the flask with foundry sand to
a desired level, placing a plurality of weights on the
upper surface of the sand and vibrating the flask and its
contents including the weights in the absence of a down-
wardly directed force on the weights other than that ofgravity. Preferably, the method includes the step of
guiding the weights for substantially solely vertical
movement during at least a portion of the step of vibrating.
Other objects and advantages will become apparent
from the following specification taken in connection with
the accompanying drawings.
Descri~tion of the Drawinas
Fig. 1 is a side elevation of an apparatus made
according to the invention~ with parts broken away for
clarity, atan lnitial stage in the operation of the ap-
paratus;
Fig. 2 is a view similar to Fig. 1 but showing a
subsequent stage in the operation of the apparatus;
Fiy. 3 is a view similar to Figs. 1 and 2 but
showing still a later stage in the operation of the
apparatus; and
Fig. 4 is a view similar to the prece~ing views
illustrating a final stage in the operation of!the ap-
paratus.
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~escription of the Preferred Embodiment
pparatus
An exemplary embodiment of an apparatus made
according to the invention is illustrated in the
various figures of drawin~ and is seen to include a
base 10 which may be disposed on an underlying sur-
face 12 such as a floor or the like. Extending up
wardly from the base 10 is an inverted, U-shaped frame
14. '
Within the frame 14 and above the base 10 there
is disposed a table 16 having an upper surface 18 defining
a flask receiving station for receipt of a flask 20. As
illustrated, the flask 20 has a pattexn 22 disposed therein
and has been fllled to a desired level with a mixture of
foundry sand and binder 24.
, While not shown herein, it is considered that the
table 16 may be provided with suitable conveyin~ means
to assist in the movement of the flask 20 to and from the
station.
The table 16 is mounted~above the base on a series
of coil springs'26. Secured to the undersurface 28 of
the table 16 are a plurality of electric motors 30 each
haviny rotary output shafts 32 to which eccentric weights
3~ are affixed.
As a result of the foregoing structure, when the
motors 30 are energized, a vert'ical vibratory force will
be applied to the table lG, and thus to the flask 20
thereon in the manner described in my previously identified
patent. '
Suspended from the upper end of the frame 14 is
a pair of''fluid cylinders 40 of the double acting variety.
Each cylinder 40 includes an extendable rod 42 and a cross
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member 44 is secured to both of the rods 42 as b~v nuts
46 such that it overlies the flask receiving station.
The cross member 44 is provided with one or more
rows of vertically extending bores or apertures 48
through which rods 50 slidably extend. Preferably, the
fit is relatively close so that movement of the rods
50 within the apertures 48 is principally limited to
the vertical direction. In other words, the apertures
48 guide the rods 50 for movement in the vertical direc-
tion.
The upper end of each of the rods 50 terminatesin a cap 52 of larger diameter than the corresponding
bore 48. The caps 52 serve as stops to limit downward
movement of the rods 50 relative to the cross member
44.
Each of t~ie rods 50, at its lower end, mounts a
- compacting head 54. The compacting heads 54 are disposed
in close adjacency and yet are relatively movable with
respect to each other by reason of the lost motion con~
nection to the cross member 44 provided by the rods 50,
the bores 48, and the stops 52.~ Each compacting head
54 has a lower surface 56 which is adapted to abut the
- sand 24 contained in the flask to compact the same. To
assure uniform compaction by each of the heads 54, it is
preferable that the ratio of the weight of all of the
individual headsand their associated rods 50 and caps 52
to the area of their surfaces 56 be equal. Generally,
but not always, this will mean that each assembly of a
head 54, rod 50 and cap 52 be of identical mass and con-
figuration.
Method
The inventive method, contemplates as a first step,the placing of a pattern in a mold flask. For example,
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this step can be accomplished by placing a pattern
such as the pattern 22 in a mold flask such as the
mold flask 20.
The next step of the method involves filling the
flasX with foundry sand, and usually a binder, to a
desired level. ~s illustrated in the drawings, this
may be accomplished by filling the flask 20 with a
foundry sand and binder mix 24 to a level well abo~e the
uppermost end of the pattern 22.
The next step of the method involves the placing
of a plurality of weights on the upper surface of the
sand. This can be accomplished using the above described
apparatus as ~ollows. Through suitable conventional con-
trols, the cylinders 40 are caused to extend their rods
42 as illustrated in Fig. 2. This in turn lowers the
cross member 44 until the rods 42 are fully extended.
In the usual case, this will bring the cross member 42
to a level just slightly above the upper edge of the flask
20 but not suficiently low as to engage the up~er surface
of the heads 54.
During the lowering proc'ess thus described, at some
point in time, the compacting surfaces 56 o~ the vari,ous
heads 54 will engage the upper surface of the sand and
bear against the same. - ` ,
The next step of the method involves the vibrating
of the flask and its contents including the weights in
the absence of a downwardly directed force on the weights
other than that of gravity. This is accomplished ~y ener-
~izing the motors 30 as illustrated in Fig. 3. Where a
generally purely vertical oscillation is desired, the
motor shafts 32 are caused to rotate in opposite direc-
~ions. Conversely, if a sideways force along with a
vertical force is desired, the motor shats 32 are caused
~o rotate in the same direction.
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As a result of this step, the sand 24 will
flow into crevices or passages, no matter how intri-
cate, in the pattern 22 in the manner described in my
co-pending application. At the same time, the force
of gravity will be continuously operatiny on the com
pacting heads 54 to cause the same to move downwardly.
Additionally, when.-the table 16 is moving upwardly,
inertial forces will tend to cause compaction of the
sand and binder mix 24.
10When the desired degree of compaction is achieved,
the moto.rs 30 may be deenergiz.ed at which time oscilla-
tion of the flask 20 will cease. The cylinders 40 may
then be caused to retract their rods 42 as illustrated
in Fig. 4. As the rods 42 retract, at some point in time,
the cross member 42 will be brought against the under-
side of the caps 52, though not necessariiy simultaneously,
and continued retraction of the rods 42 w~ill cause the
heads 54 to be moved outwardly to a location above the
- flask receiving station as seen in Fig. 4. At this point,
the flask 20 may be removed from the apparatus and moved
to any desired location for further processing.
It will also be observed that during the fore-
going method, a step of guiding the heads 54 for sub-
stantially solely vertical movement occurs during at
least a portion of the step of vibrating. This step
is performed in the above apparatus by the relationship
of the bores 48 to the rod 50 as described previously
and assures uniform compaction of the sand and binder
mix 24 within the flask 20. Finally, it will be ob-
served tha.t at no time is there a downwardly directedforce on the heads 54 other than that of gravity. Thus,
the force of gravity is utilized to avoid the need for
operators to force the heads 54 downwardly and any source
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of energy therefore, Consequently, the apparatus is
greatly simplified over prior art apparatus and is
considerably less expensive to build. Nonethless, the
advantages of combined vibratory and non-vibratory
compaction of the sand and binder mix 24 are retained.
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