Improvements in or relating to the Drying of Sand and Loam Molds Used in Dry Sand Castings.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to the Drying of Sand and Loam Molds
Used in Dry Sand Castings.
I, NOAH SHAW, of Eau Claire, in the County of Eau Claire and State of Wis-
consin, United States of America, Manufacturer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to an improved process for drying sand and loam molds
used in dry sand castings. The main and primary object of the invention is to
provide a process of this character which shall insure the uniform, thorough and
speedy drying of sand molds for dry sand castings whereby the many objection-
able features of the ordinary method of drying such molds will be overcome.
"
Heretofore dry sand castings have been rendered very expensive to make by
reason of expensive appliances used in connection with drying the sand molds;
the liability to loss by defective molds, the defects of which remain undiscovered
until the loss occurs; the excessive length of time required in drying the molds,
and the cleaning thereof. In the first place, in the processes heretofore carried
out in dry sand casting work, iron flasks are invariably used except for such
molds as are made in the floor or loam where brick work is substituted for the
flask, and in the carrying out of most of the ordinary processes, the molds are
made in iron flasks, and finished with the ordinary blacking" or wash."
The molds and flasks are then placed in ovens and subjected to heat from twelve
to forty-eight hours, according to the nature of the mold, and when sufficiently
dried, the molds and flasks are removed from the ovens, the cores put in place,
and the molds closed before the molten metal is poured into the molds. In
contradistinction to this process, the present invention contemplates a process,
in the carrying out of which the molds are completely finished, the cores put in
place while the molds are yet soft and not liable to crumble or crush, and the
molds closed and kept closed until they are opened to remove the casting. This
process or method not only effects a great saving of time in the preparation of
the molds for the casting, but also insures perfect and complete molds and there-
fore perfect castings.
In the uniform drying of the molds, the process contemplated by the present
invention possesses great advantages over the ordinary process of molding large
castings. In such work the castings are made in the floor or loam and the
molds are dried by the use of baskets of charcoal placed in different parts of
the mold. Moreover, as the molds cannot be closed to retain the heat, portions
of the molds are not reached by the heat and are therefore, improperly dried,
while, in addition to this, other portions of the mold are burned and the molds
are filled with ashes and cinders, requiring much time and trouble in cleaning.
In this connection, it will also be noted that molds which are dried in an oven
are always left open and are filled with ashes and cinders, which must be cleaned
out before the molds can be closed. All these disadvantages are overcome by
the present invention, in view of the fact that the molds can be completely
finished and closed up ready for casting before the same are dried.
In the accomplishment of the objects sought for, the invention essentially

page_text: consists in forcing heated air, under pressure, into the molds after the same are
finished and closed, thereby forcing the moisture in the sand of which the molds
are composed, outward through the pores of the sand, whereby the heated air
which follows, converts the moisture into steam or vapor and leaves the pores
of the sand open for the free escape of the gas generated by the molten metal 5
when poured into the mold.
While it is the purpose of the present invention to have the heated air forced,
under pressure, uniformly through the walls of the mold, still this is not always
possible, as the walls of some molds are of varying thickness and of different
degrees of density; and for the same reason, at times, it might not be possible 1
for the heated air to pass through all of the walls of the mold, although this
would not interfere with the successful carrying out of the invention. Further-
more, while it is contemplated to use the process in connection with a mold that
has been completely finished and closed, still it must be obvious that the mold
need not necessarily be a finished one, as the only pre-requisite to the successful
operation of the process is that the mold be tightly closed. Therefore, it will
be understood that it is only essential to the success of the process that the mold
be closed, and that the fundamental feature of the invention consists in forcing
heated air, under pressure, directly into the interior mold-cavity, and from thence
out through the pores in the walls of the mold.
To carry out the process referred to, different forms of apparatus may be
employed, but the apparatus most convenient for the purpose is set forth in the
following description:
A suitable furnace is provided at one end with a fire box and with a longitudinal
heat chamber, in which is arranged a heating cylinder extending from end to
end of the furnace. The heating cylinder is designed to be heated to a sufficient
temperature by the heat within the furnace and is provided with opposite con-
tracted ends, projected through the opposite ends of the furnace. One contracted
end of the heating cylinder has connected thereto one end of a cold-air pipe,
the other end of which is connected with an air compressor of the ordinary con-
struction, and adapted to force air under pressure through the cold-air pipe
into and through the cylinder. The cold-air pipe is provided at a suitable point
with an ordinary safety valve and with a regulating valve to control the supply
of air from the compressor to the heating cylinder. At the end opposite the
connection of the pipe therewith, the heating cylinder has, connected thereto,
one end of a hot-air pipe, which is placed below the molding floor. The hot-air
pipe has suitably connected therewith, at any suitable point, an ordinary ther-
mometer, to indicate the temperature of the air, and at other points the hot-air
pipe has connection therewith, branch hot-air pipes, each of which pipes is adapted
to be fitted to the opening in the top of a finished and closed dry sand mold
of the ordinary construction, and it is placed on the molding floor in the position
in which it remains while the casting is being made. Each of the branch pipes
is provided at suitable points with an ordinary ball and socket joint, the con-
struction of which is well known, so that such pipes can be readily adjusted to
and away from the molds, and each of the pipes is also provided with a regulating
valve, to regulate the pressure of air in the mold, and also with a suitable
pressure gage, which indicates the pressure of air that is introduced into the
mold for the purpose of quickly drying the same.
A branch cold-air pipe is connected with the hot-air pipe and the cold-air
pipe, and is provided with an ordinary cut-off valve and an ordinary pressure
gage.
The function of the branch cold-air pipe is to admit cold air directly
into the hot-air pipe, in order to regulate or modify the temperature of the hot
air forced through the said pipe and the branch hot-air pipe connections there-
with, and by observing the thermometer, the regulating valves can be so manipu
lated as to properly control the temperature of the hot air which is introduced
into the molds. The steps of the process will be readily apparent from the
description of the apparatus preferably employed, for it will be obvious that when

page_text: the flask is closed with the finished mold therein, it is simply necessary to connect
one of the branch pipes with the top opening of the mold. The air will then
be forced under pressure from the compressor into the heating cylinder, where
it is heated to the desired degree of temperature, and is still forced, under pressure
in its heated condition, through the hot-air pipes into the mold. As before
stated, the heated air which passes into the mold, under pressure, works through
the said mold outward and thoroughly and uniformly dries the mold in a very
short space of time, ranging from five to thirty minutes, and as the hot-air is
forced through the mold, the same dries up the moisture and leaves the pores
open, through which the gases generated by the molten metal may freely escape.
When the apparatus is first started, the hot air is admitted to the mold at
about one pound pressure, but as the mold dries, the pressure is accordingly
increased by opening the valve until the gage shows the full pressure indicated
by the pressure gage, which is five pounds pressure to the square inch.
In connection with this process, it will be obvious that wooden flasks may be
employed in place of the heavy iron flasks, and furthermore it will be obvious
that by introducing the hot air into the mold under pressure, if there is any
opening in the mold through which the molten metal could run out when the
mold is being filled, it is readily discovered and accidents resulting from such
defects are thereby obviated. This is a very important advantage, for the reason
that large castings are frequently spoiled and sometimes entirely lost by the
running out of the metal through defective openings in the mold which remain
undiscovered.
One of the ways in which the hot air pipes may be arranged in connection
with the mold will appear from the following. A form of mold having a
rectangular sand body, enclosed within a correspondingly-shaped iron flask
provided in its sides, ends and bottom with a plurality of vent openings is pro-
vided for the free passage of the heated air after being forced through the pores
in the walls and bottom of the mold body. In the form of mold described, the
sand body thereof is provided in its upper edge with a continuous annular vent
channel, with which communicate a plurality of vertical vent holes, formed in
the side and end walls of the sand body, and subserving the usual function of
providing for the escape of a portion of the gas generated by the molten iron,
as is always the practice, both in dry and green sand molding work. The mold
is provided with the ordinary sand cover section, packed within the upper or cope
section of the flask, which section of the flask is designed to be connected with
the lower or drag section thereof in the usual manner. While a form of sand
mold has been specifically described, it will, of course, be understood that the
process may be effectively carried out in connection with any form of sand mold
having a sand cover section and enclosed within a perforate flask, the perforations
of which flask permit the free escape from the mold of the heated air, and the
cover section of the mold is formed with a pipe opening to snugly receive therein,
one end of the pipe connection for delivering heated air into the interior of the
finished and closed mold for the purpose of drying the sand in the manner herein-
before fully explained.
() Improvements in or relating to the Drying of Sand and Loam Molds
Used in Dry Sand Castings.
I, NOAH SHAW, of Eau Claire, in the County of Eau Claire and State of Wis-
consin, United States of America, Manufacturer, do hereby declare the nature of

page_text: This invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This invention relates to an improved process of drying sand and loam molds
used in dry-sand castings.
The main and primary object of the invention is to provide a process of this
character which shall insure the uniform, thorough, and speedy drying of sand
molds for dry-sand castings, whereby the many objectionable features of the
ordinary method of drying such molds shall be overcome.
وو
or
Heretofore dry-sand castings have been rendered very expensive to make by
reason of expensive appliances used in connection with drying of the sand molds,
the liability to loss by defective molds, the defects in which remain undiscovered
until the loss occurs, the excessive length of time required in drying the molds,
and the cleaning thereof. In the first place, in the processes heretofore carried
out in dry-sand-casting work, iron flasks are invariably used, except for such
molds as are made in the floor or loam, where brick-work is substituted for the
flask, and in the carrying out of most of the ordinary processes the molds are
made in iron flasks and finished with the ordinary "blacking
"wash."
The molds and flasks are then placed in ovens and subjected to heat from about
twelve to forty-eight hours, according to the nature of the mold, and when
sufficiently dried the molds and flasks are removed from the ovens, the cores put
in place, and the molds closed before the molten metal is poured into the molds.
In contradistinction to this process, the present invention contemplates a process
in the carrying out of which the molds are completely finished, the cores put in
place while the molds are yet soft and not liable to crumble or crush, and the
inolds closed and kept closed until they are opened to remove the casting. This
process or method not only effects a great saving of time in the preparation of
the molds for the casting, but also ensures perfect and complete molds, and
therefore perfect castings.
In the uniform drying of the molds, the process contemplated by the present
invention possesses great advantage over the ordinary process of molding large
castings. In such work the castings are made in the floor or loam and the
molds are dried by the use of baskets of charcoal placed in different parts of
the mold. Moreover, as the molds cannot be closed to retain the heat portions
of the molds are not reached by the heat and are therefore improperly dried,
while in addition to this other portions of the mold are burned and the molds
are filled with ashes and cinders, requiring much time and trouble in cleaning.
In this connection, it will also be noted that molds which are dried in an oven
are always left open and are filled with ashes and cinders, which must be cleaned
out before the molds can be closed. All these disadvantages are overcome by
the present invention, in view of the fact that the molds can be completely
finished and closed up ready for casting before the same are dried.
In the accomplishment of the objects sought for, the invention essentially
consists in forcing heated air under pressure into the molds after the same are
finished and closed, thereby forcing the moisture in the sand of which the molds
are composed outward through the pores of the sand, whereby the heated air
which follows converts the moisture into steam or vapor and leaves the pores
of the sand open for the free escape of the gases generated by the molten metal
when poured into the mold.
While it is the purpose of the present invention to have the heated air forced,
under pressure uniformly through the walls of the mold, still this is not always
possible, as the walls of some molds are of varying thickness and of different
degrees of density; and for the same reason at times it might not be possible
for the heated air to pass through all of the walls of the mold, although this
would not interfere with the successful carrying out of the invention. Further-
more, while it is contemplated to use the process in connection with a mold that
has been completely finished and closed, still it must be obvious that the mold
need not necessarily be a finished one, as the only pre-requisite to the successful

page_text: operat of the process is that the mold be tightly closed. Therefore, it will
be understood that it is only essential to the success of the process that the mold
be closed and that the fundamental feature of the invention consists in forcing
heated air under pressure directly into the interior mold-cavity and from thence
out through the pores in the walls of the mold.
To carry out the process referred to, different forms of apparatus may be
employed, but the form of apparatus most convenient for the purpose is illus-
trated in the drawings, in which-
Figure 1 is a plan view of a mold-drying apparatus constructed to carry out the
process contemplated by this invention.
Figure 2 is a side elevation, partly in section, of the same.
Figure 3 is a detail elevation showing the connection of the hot-air pipe with
a mold for the purpose of drying the same.
Figure 4 is a plan view of the under side of the cover or cope section of the
mold and its inclosing flask.
Figure 5 is a vertical sectional view of a complete mold and its inclosing flask,
showing the hot-air pipe connection therewith.
Figure 6 is a top plan view of the mold with the cope or cover section removed.
Referring to the drawings, the numeral 1 designates a suitable furnace pro-
'vided at one end with a fire-box 2 and with a longitudinal heating-chamber 3,
in which is arranged a heating cylinder 4, extending from end to end of the
furnace. The heating-cylinder 4 is designed to be heated to a sufficient tem-
perature by the heat within the furnace and is provided with opposite contracted
ends 5, projected through the opposite ends of the furnace. One contracted
end 5 of the heating-cylinder 4 has connected thereto one end of a cold-air-pipe 6,
the other end of which is connected with an air-compressor 7, of an ordinary
construction, and adapted to force air under pressure through the pipe 6 into
and through the cylinder 4. The cold-air pipe 6 is provided at a suitable point
with an ordinary safety-valve 8 and with a regulating-valve 9 to control the
supply of air from the compressor 7 to the heating-cylinder 4. At the end
opposite the connection of the pipe 6 therewith the heating-cvlinder 4 has con-
nected thereto one end of the hot-air pipe 10, which is placed below the molding-
floor, as illustrated in Figure 3 of the drawings.
The hot-air pipe 10 has suitably connected therewith at any suitable point
an ordinary thermometer 11, diagrammatically illustrated to indicate the tem-
perature of the air, and at other points the pipe 10 has connected therewith the
branch hot-air pipes 12, each of which pipes is adapted to be fitted to the opening
in the top of a finished and closed dry-sand mold 13 of the ordinary construction
and which is placed on the molding-floor in the position in which it remains
while the casting is being made. Each of the branch pipes 12 is provided at
suitable points with an ordinary ball-and-socket joint 14, the construction of
which is well known, so that such pipes can readily be adjusted to and away from
the molds, and each of the pipes 12 is also provided with a regulating-valve 15
to regulate the pressure of air in the mold and also with a suitable pressure-
gage 16, which indicates the pressure of air that is introduced into the mold
for the purpose of quickly drying the same.
A branch cold-air pipe 17 is connected with the pipe 10 and the pipe 6 and
is provided with an ordinary cut-off valve 18 and an ordinary pressure-gage 19,
similar to the gage 16. The function of the branch cold-air pipe 17 is to admit
cold air directly into the pipe 10 in order to regulate or modify the temperature
of the hot air forced through the pipe 10 and the branch-pipe connections 12
therewith, and, by observing the thermometer 11 the valves 9 and 18 can be so
manipulated as to properly control the temperature of the hot air which is intro-
duced into the molds.
The steps of the process will be readily apparent from the description of the
apparatus preferably employed. for it will be obvious that when a flask is closed
with the finished mold therein it is simply necessary to connect one of the branch

page_text: pipes 12 with the top opening of the mold. The air will then be forced under
pressure from the compressor 7 into the heating-cylinder 4, where it is heated
to the desired degree of temperature, and is still forced under pressure in its
heated condition through the pipes 10 and 12 into the mold. As before stated,
the heated air which passes into the mold under pressure works through the said
mold outward and thoroughly and uniformly dries the mold in a very short space
of time, ranging from five to thirty minutes, and as the hot air is forced through
the mold the same dries up the moisture and leaves the pores open, through
which the gases generated by the molten metal may freely escape.
When the apparatus is first started, the hot air is admitted to the mold at
about one-pound pressure; but as the mold dries the pressure is gradually
increased by opening the valve 15 until the gage 16 shows the full pressure
indicated by the gage 19, which is about five-pounds pressure to the square inch.
In connection with this process, it will be obvious that wooden flasks may
he employed in place of the heavy iron flasks, and, furthermore, it will be obvious
that by introducing the heated air into the mold under pressure if there is any
opening in the mold through which the molten metal could run out when the
mold is being filled, it is readily discovered and accidents resulting from such
defects are thereby obviated. This is a very important advance, for the reason
that large castings are frequently spoiled and sometimes entirely lost by the
running out of the metal through defective openings in the mold which remain
undiscovered.
The mold 13 is simply illustrated diagrammatically in Fig. 3 of the drawings
to show one of the ways in which the hot-air pipes may be arranged in connection
therewith; but this mold is illustrate in detail in Figs. 4, 5 and 6 of the
drawings. By reference to these figures of the drawings it will be observed
that I have illustrated a form of mold having a rectangular sand body 14°, inclosed
within a correspondingly-shaped iron flask 15ª, provided in its sides, ends and
bottom with a plurality of vent-openings 16", which provide for the free passage
of the heated air after being forced through the pores in the walls and bottom
of the mold-body. In the form of mold illustrated the sand body 14° thereof
is provided in its upper edge with a continuous annular vent-channel 17%, with
which communicate a plurality of vertical vent-holes 18, formed in the side
and end walls of the sand body and subserving the usual function of providing
for the escape of a portion of the gas generated by the molten iron, as is always
the practice both in dry and green sand mold work. The mold 13ª is provided
with the ordinary sand-cover section 19ª, packed within the upper or cope
section 20 of the flask, which section of the flask is designed to be connected
While a form of
with the lower or drag section thereof in the usual manner.
sand mold has been specifically described and illustrated, it will, of course, be
understood that the process may be effectively carried out in connection with any
form of sand mold having a sand-cover section and inclosed within a perforate
flask, the perforations of which flask permit of the free escape from the mold
of the heated air, and the cover section of the mold is formed with a pipe-opening
21 to snugly receive therein one end of the pipe connection 12 for delivering
heated air into the interior of the finished inclosed mold for the purpose of
drying the same in the manner hereinbefore explained.
From the foregoing it is thought that the details of the process herein set forth
will be readily understood by those skilled in the art, and various changes in the
minor details of carrying out the process may be resorted to without sacrificing
any of the principles or advantages of the invention.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
:
1. A process for drying closed sand and loam molds, which consists in forcing

page_text: heated air under pressure directly into the interior mold-cavity, and from thence
out through the pores in the walls of the mold.
2. A process for drying sand molds which consists in forcing heated air under
pressure into and outward uniformly through all of the porous walls of a finished
and closed mold, substantially as described.
Dated this 12th of
1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.