Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKGROUND OF THE INVENTION
The presenk invention relates to a method of
moldïng a mold, particularly to a method of molding a
drag mold part, wherein the drag mold part is produced ~:
5 by a mold forming method comprising steps of passing :
compressed air through molding sand filled in a spacè
defined by a molding flask and a pattern to compact and
consolidate the molding sand, particular to the molding
sand in the vicinity of the pattern, and then squeezing
the molding sand as a whole by means of a squeeze
plate.
The present invention also relates to an
apparatus used for the method.
There have been problems :in the production of
cope and drag mold parts by the above mentioned mold
forming method, in case of using a match plate type
pattern; that is: Nhen the molding sand is floated
and moved under a high pressure, toward the pattern defin- ~`
ing a deep recess in itself or between itself and the
molding flask in the production of the drag mold part,
the molding sand is not sufficiently attached to the
surface of the pattern, while when the molding sand is
floated under a low pressure, the portion of the molding
sand which is in the vicinity of the pattern is not
compacted to a high density so that the mold formed
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does not have a suEficient hardness.
Therefore, it has heretofore been considered impossible
to make a complicated form of a drag mold part simultaneously with
a cope mold part by the above mentioned molding method.
An object of the present invention is to eliminate the
above-mentioned inconveniences.
To this end, the present invention provides a method of
producing a drag mold part, comprising the steps of placing molding
sand in a space defined by a drag molding flask and a squeeze plate
slidably disposed in said drag molding flask, said squeeze plate
being provided with a means for blowing compressed air in the
upward direction, joining a pattern having a plurality of air
discharge bores to the upper end of said drag molding flask in
which the molding sand is placed, blowing first compressed air
from said blowing means provided in said squeeze plate so as to
move the molding sand upwardly toward said pattern, blowing from
said blowing means second compressed air at a flow rate or
pressure greater than that of said first compressed air so as to
increase the density of the molding sand in the vicinity of said
pattern, and upwardly moving said squeeze plate to squeeze the
molding sand as a whole.
The invention also provides an apparatus for producing a
drag mold part, comprising a vertically movable drag molding flask,
a squeeze plate slidably fitted in said drag molding flask, a
pattern having a plurality of air discharge bores and arranged to
fit in said drag molding flask, means for carrying said pattern
above said drag molding flask, means for upwardly moving said drag
molding flask to fit the same with said pattern thereon, means,
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provided in said squeeze plate, for blowing compressed air, and
means for selectively feeding to said flowing means compressed
air at a different flow rate or pressure, respectively.
The above and other objects as well as advantageous
features of the invention will become clear from the following
description of the preferred
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1 embodiment taken in conunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1-3 are partially omitted sectional views
i]lustrating the mold-making steps in a method according
to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIl~ENT
An embodiment of the present invention will
be described with reference to the accompanying drawings.
Referring to the drawings, reference numeral
1 denotes a drag upset frame which can be vertically
moved by cylinders 2. In the lower opening of the
drag upset frame 1, a squeeze plate 5 secured to an
upwardly movable piston rod 4 is fitted. An air-tight
seal 5a is fitted around the peripheral wall of the
squeeze plate 5 so that the later is air tightly fitted
into the drag upset frame 1. The squeeze plate 5 has
an upper and a lower walls defining a chamber 6 and
air flowing bores 7 in the upper wall through which
the chamber 6 communicates with the outside. The lower
wall of the squeeze plate 5 has another bore 8 through
which compressed air is fed thereinto. To the air feed
bore 8, a flexible conduit 9 is connected, and the
flexible conduit 9 is in turn connected to a compressed
air source (not shown) via a main piping system 12
including a shut-off valve 10 and a flow regulating
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1 valve 11.
The main piping system 12 is connected with
a first by-pass piping system 13 which is branched-off
from the main piping system 12 upstream of the flow
regulating valve 11 to bypass the valves 11, 10 and
then is jointed to the main piping system 12 down stream
of the shut-off valve 10. The first by-pass piping
system 13 is provided with a first by-pass shut-off valve
10a and with a first by-pass flow regulating valve lla
upstream of the first by-pass shut-off valve lOa. The
first by-pass piping system 13 is in turn connected a
by~pass piping system 14 which is branched-off from the
first by-pass piping system 13 upstream of the flow
regulating valve lla to bypass the valves lla, 10a and
is jointed to the first by-pass piping system 13
downstream of the first by-pass shut-off valve 10a.
The second by-pass piping system 14 is further provided
with a second by-pass shut-off valve lOb and with a
second by-pass flow regulating valve llb upstream of
the second by-pass shut-off valve 10b.
Above the drag upset frame l, hollow roller
conveyors 15 are disposed, which are spaced from each
other such that the drag upset frame 1 can be upwardly
moved therebetween. The hollow roller conveyors 15
are provided thereon with a drag molding flask 16 which
can be brought to and away from the upper surface of
the drag upset frame 1.
On the drag molding flask 16, a match plate type
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1 pattern 17 is disposed, which can be moved onto and
away from the drag molding flask 16 on the side opposed
to the drag upset frame l; that is: the upper side as
seen in the drawings. The pattern 17 has a recess 19
defined in itself and recesses 18 defined between
itself and the molding flask 16, which are difficult
to be filled with molding sand, and also an upper and
a lower patterns defining therebetween a chamber 20
which is communicated with the outside. The pattern 17
is further provided in -the lower pattern thereof with
narrow passages 21 communicated with the chamber 20.
The passages 21 are positioned in a larger number in
the bottoms of the recesses 18, 19, than the other
portions thereof. In the passages 21, vent plugs (not
shown) are fitted.
The flow regulating valve 11 is adjusted so
as to supply compressed air at such a rate that is
enough for the molding sand 23 to be upwardly conveyed
at a low speed with compressed air blown from the
squeeze plate 5. The regulating valve lla is adjusted
so as to supply compressed air at such a large rate
that is enough to generate a high pressure in the molding
sand 23 due to the pressure losses in the molding sand
23 and passages 21. The flow regulating valve llb is
adjusted so as to supply air at such a rate that is enough
to prevent the raised molding sand 23 from dropping.
In the accompanying drawings, a cope molding
flask, an upper drag upset frame, and an upper squeeze
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1 plate which are to be mounted on the pattern 17 are
omitted to make simple the examination of the present
invention.
In an apparatus having the above-described
construction, a drag molding flask 16 is moved by the
roller conveyors 15 just above a drag upset frame into
which a squeeze plate 5 is fitted. Cylinders 2, 2, 3
are then actuated to upwardly move the drag upset frame 1
and the squeeze plate 5 to lift the drag molding flask
16 from the roller conveyors 15 to a small extent and
then stop the same. A predetermined amount of molding
sand 23 is thereafter fed from a hopper (not shown)
into a space defined by the drag upset frame 1, the
squeeze plate 5 and the drag molding flask 16, and
].5 subsequently, a pattern 17 is mo~ed to the upper portion
of the drag molding flask 16. The cylinders 2, 2, 3
are then actuated to press the drag molding flask 16
against the lower surface of the pattern 17 as shown
in Fig. 1.
The valve 10 is opened for a predetermined period
of time so as to flow compressed air from the compressed
air source onto the molding sand 23 via the conduit 9, the
feed bore 8, the chamber 6, and the air flowing bores 7.
The compressed air flow by the above-mentioned operation
serves to upwardly move the molding sand 23 at a low
speed. The molding sand 23 flows much, especially,
into a recess 18 having many narrow passages in
its bottom to allow the recesses 18, 19
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1 to be filled with the molding sand 23. The compressed
air is then discharged outside via the passages 21
and the chamber 20.
Accordingly, the molding sand 23 strongly
impinges upon projections on the pattern 17 so as to
be forced into the recesses 18, 19 without being !'
solidified so that the density of the molding sand 23
is increased in the recesses 18, 19.
When the valve 10 is then closed while opening
the valve lOa for a predetermined period of time, compressed
air is flown in the same manner as mentioned above.
This compressed air is of a large capacity to generate
a high pressure under the molding sand 23. Therefore,
the density of the molding sand 23 which is close to
the surface of the pattern 17 is increased much and
the sand ls then solidified. (Refer to Fig. 2.)
When the valve lOa is closed while holding
the second by-pass shut-off valve lOb the piston rod 4
in the cylinder 3 is extended and thereby upwardly
move the squeeze plate 5 so that the molding sand 23
as a whole is squeezed. (Refer to Fig. 3.) The dropping
of the molding sand 23 is prevented by the opening of
the second by-pass shut-off valve lOb. This condition
is continued until a squeezing operation by the squeeze
plate 5 has started. In the case where there is no
possibility of dropping of the molding sand, a second
by-pass piping system 14 having the second by-pass
shut-off valve lOb and the second by-pass flow regulating
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1 valve llb, may be omitted.
The purpose of a squeezing operation which
is conducted in the above-mentioned manner is to
consolidate the molding sand which is not sufficiently
consolidated other than such a portion thereof which
is highly consolidated with the compressed air along
the surface of the pattern 17. This squeezing operation
works a little to the molding sand which has been highly
consolidated by compressed air.
When the cylinders 2, 2, 3 are backwardly
moved to lower the drag upset frame 1 and the squeeze
plate 5, the drag molding flask 16 is removed from the
pattern 17 to be returned on the roller conveyors 15.
At this time, a drag mold part has been formed in the
drag molding flask 16.
This molding flask removing operation can be
easily conducted by introducing compressed air onto the
molding sand 23 through the passages 21. ~or this
purpose, another piping system 14a including a three-way
valve lOc is provided between the passages 21 and the
second by-pass system 14. The drag upset frame 1 and
the squeeze plate 5 are removed from the drag molding
flask 16 when they are do~nwardly rnoved to a small
extent.
The drag mold part with the molding flask
which is returned on the roller conveyors 15 is transferred
to a mold combining position without being upside down.
The drag mold part is then joined to an upper mold part
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1 which has been molded on the pattern 17 at the same
time (description will be omitted), so as to ~orm a
complete mold.
Onto the drag upset frame 1 which a drag mold
part with the molding flask has been brought away, a
new empty drag molding flask is introduced, and the
above-mentioned operation is repeated]y conducted.
In the above embodiment, the drag molding flask
16 is moved onto and removed from the upper surface of
the drag upset frame 1 to form a drag mold part.
However, the drag upset frame 1 can be eliminated
so that the squeeze plate 5 is directly fitted into the
drag molding flask 16. In this case, the mold which
has been completed is removed from the molding flask 16.
In the embodiment, the flow rate of the
compressed air supplied through the squeeze plate 5 is
regulated but the same e~fect can be obtained by
regulating the pressure thereof.
Although the shut-off valve lO is closed
simultaneously with the first by-pass shut-off valve 10a
in the above embodiment, the shut-off valve 10 may be
kept opened.
As may be clearly noted from the above description,
a method according to the present invention comprises
of flowing compressed air at such a rate that is enough
for molding sand to be upwardly moved at a low speed
from the squeeze plate so as to force the molding sand
into deep recesses defined in a pattern; subsequently
l flowing a large amount of compressed air to compact
and consolidate to a high density the molding sand
which is close to a pattern; and thereafter squeezing
the molding sand as a whole by the squeeze plate to
consolidate the whole of the molding sand. Accordingly,
in spite o~ the fact that the deep recesses are provided
in the pattern and formed between the pattern and the
molding flask, the molding sand can be fully introduced
thereinto and is compacted and consolidated to a high
density. ~ method according to the present invention
has an extremely high effect especially when it is applied
to the production of a drag mold part by using a match
plate type pattern. In addition, a drag mold part
produced can be joined without turning it upside down.
This serves to prevent a mold from being hurt while
it is handled.
The present invention is not, of course, limited
to the above embodiment; it may be modified in various
ways within the scope of the appended claims.
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