Note: Descriptions are shown in the official language in which they were submitted.
~ ~6~8~
APPARAT~S FOR PR03UCING BRICK-SH~PED BLOCKS OE' DRY_ICE
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to apparatus
for producing bloc~s of dry ice from liquid carbod dioxide. More
particularly, it relates to an improved apparatus whi.ch wlll
rapidly and continuously produce bric}c-shaped blocks of dry ice,
and which is designed to be especially use~ul for restaurants,
ice cream shops, confectionaries, and the like.
2. Descripti.Qn of the Prior Art
_
The basic process for making block dry lce from liquid
carbon dioxide has long been known, and involves first spraylng
t~'le liq~lid carbon dioxide lnto a chamber to form dry ice snow,
and then compressing -the snow into a block. Over the years
various kinds of apparatws for carrying out this basic process
have been devi.sed~ and typical of such conventional apparatus
is tha-t which is the subject of Great Britain Complete Specifi-
cation No. 433,018, accepted August 7, 1935. Referring to the
drawirlgs of the present application, FIGS. 7 and 8 illustrate
the prior art as described in th.i.s British patent.
As shown in said FIGS. 7 and 8, a charging cylinder
50 is provided with an inlet noz~le 51 at its upper end, and is
positioned vertically above a vertically movable press cylinder
53. A transversly ~ovable shut~er 52 is positioned between the
a~J
cylinders 50 and 53, and is operable by a hydraulic ~ctuator
54. The press cylinder 53 carries an annular piston 58 thereon
that is slidable within a cylinder 58a, and which is moved toward
and away from the shutter assembly by hydraulic pressure.
press plunger 55 is mounted for vertical movement within the
press cylinder 53, and carries a piston 5~ on its lower end
that is received within a cylinder 56a and which is operable by
hydraulic pressure to raise and lower the press plunger 55.
Liquid carbon dioxide is sprayed into the charging
!0 cylinder 50 through -the inlet nozzle 51, with the shutter 52 in
a closed position. As the carbon dioxide is sprayed from the
nozzle 51 it changes to dry ice snow through adiab~tic expansion.
and accumulates in the charging cylinder. When a sufficient
quantity of dry ice snow has been formed the shutter 52 is opened
L5 by the hydraulic actuator 54, and the snow then falls by gravity
into the lower, press cylinder 53, which has been elevated so
that its upper end is in con-tact with the shu-tter assembly. The
shutter 52 is then closed and the press plunger 55 is el~vated
by hydraulic pressure, to form a block of solid dry ice 57 from
'O the snow. r~hite the press plunger 55 is operating, the charging
cylinder 50 is again sprayed wi-th liquid carbon dioxide to form
the next charge of dry ice snow for the press cylinder 53.
After the block 57 has been formed the press cylinder
53 is lowered while the press plunger 55 remains ele~ated, until
?S the respective components reach the ~elationship shown in E'IG. 8j
wherein the block 57 of dry ice has been pushed from the cylinder
53 and stands e~posed on the press plunger 55. The block 57 is
then removed, and the apparatus is ready for another cycle.
~ ~B~
Whlle the apparatus of the noted sritish patent can
successfully produce cylindrical bloc~s of dry ice, it is not
fully satisfactory for all applications, especially in those
instances where considerable ~uantities of brick-shaped dry ice
need to be produced in mlnimum time, with a minimum of labor.
Among the problems with such prior apparatus are the following:
1. As will be noted from the brief description given
of the apparatus of the British pa~ent, the press
cylinder 53 must be vertically movable and must
be repeatedl~r driven up and down by hydraulic
pressure to provide for removal of the formed dry
ice block 57. This requires a rather complicated
and expensive mechanical structure which must be
maintained, and which is subject to wear and
brea]cdown.
2. ~n order to provide for automatic operation of the
device of the British patent, transferring means
must be added thereto to automatically remove the
dry ice block 57 after the press cylinder 53 has
been lowered. Any such transferring means must
be of a rather complicate~ esign, so as no-t to
interfere with the raising and lowering of the
press cylinder 53.
3. Because the dry ice snow supplied into the press
cylinder 53 from the charging cylinder 51 in the
apparatus of the British patent must have`a low
density, it is necessary to have a lengthy press
cylinder 53 in order to produce large blocks of
solid dry ice. This means that the press cylinder
53 and the hydraulic actuator 56 must both have
~ :~668~3
'` ':
~ - 4 -
lengthy strokes~ which increases the size
of the apparatus and hence its cost.
4. During compression of the dry ice snow
in the press cylinder 53 of the apparatus
described in the British patent, any gaseous
carbon dioxide contained in the snow will
be shut in the solid dry ice block 57. This
trapping of gaseous carbon dioxide is un-
desirable in that it affects the speed and
quality of the pressing operation, and
results in dry ice of a quality tha~ is
uneven and which is prone to early cracking
and breakup.
5. In order to operate the device o~ the Britsh
patent continuously, two shutters must be
installed. Further, continuous operation of
the device in the British patent will result
in some of the dry ice snow adhering to the
walls of the charging cylinder Sl and remaln~
ing therein, which makes it difficult to
constantly produce solid dry iee blocks of
uniform size and weight.
There is need for an apparatus for making brick-
shaped bLocks of dry ice rom liquid carbon dio~ide that
minimizes the size of the equipment, requires a minimum of
moving elemen~s, controls the problem of trapping gaseous
carbon dioxide in the dry ice, and which ~a~ repeatedly
and rapidly produce dry ice blocks of high quality and
substantially uniform characteristicsO The apparatus of
the present inv~ntion is intended to fulfill that need.
1 ~6~,5~
~ 4a -
SUMMARY OF THE INVEN~ION
According to the invention there is provided an
apparatus for producing blocks of dry ice from liquid
carbon dioxide, comprising: a supporting frame; an upper,
charging mold mounted on said supporting frame and having
an outlet at the lower end thereof; a lower, press mold
mounted on said supporting frame beneath said charging
mold and spaced therefrom~ said press mold having an inlet
opening at the upper end thereof in alignment with said
outlet opening; a press piston slidably mounted within
said press mold; actuator means connected with said press
piston, and operable to move it between lowered and
elevated positions; nozzle means mounted near the upper
end of said charging mold, and arranged to inject liquid . . :
carbon dioxide into said charging mold to form dry ice
snow; transfer means mounted to confront the space be-
tween said upper and said lower molds; and shutter means
carried by said supporting frame and received in the space
between said upper and said lower molds, saLd shutter
means including: a shutter having an extension project- :
ing forwardly from the front, top edge thereof, the top
surfaces of said shutter and said extension being con~
tinuous, and said extension and the front face of said
shutter defining a recess that is open at the bottom and
front thereof; and actuator means arranged to move said
shutter forwardly and backwardly between a fully closed
position, wherein said shutter closes both said outlet and
said inlet, an outlet closed position, wherein said charg-
ing mold outlet is closed by said extension and said recess
8 ~ '.i
- 4b ~
is positioned over said press mold inlet, and a fully open
position wherein both said inlet and said outlet are open
and in communication with each other, whereby dry ice snow
is accumulated in said charging mold while said shutter is
in said fully closed and said outlet closed positions, and
is passed as a charge into said lower, press chamber when
said shutter is in said fully open position; said press
piston and said press actuator means being effective to
compress said dry ice snow charge into a block of dry ice
when said shutter is in said fully closed position, and
being further effective to elevate said block of dry ice
and place it in said recess when said shutter is in said
outlet closed position; and said shutter and said shutter
actuator means being effective to transport said dry ice
block to said transfer means when said shutter is there-
after moved from said outlet closed position to said fully
closed position.
The apparatus of the present invention thus
includes an upper, charging mold positioned above a lower,
press mold, the two molds being separated by a shutter
assembly that includes a
~ :~B68~3
-transversely movable shutter member. Unlike in the appara-t~s
described hereinabove, both of the molds in the present invention
are fixed in position within a frame, and need not be moved
ver-tically during the manufacture of dry ice blocks. The lower
end of the upper mold has an outlet opening and the upper end of
the lower mold has an inlet opening, and these two openings are
opened or closed by forward and rearward movements of the shutter
member.
The upper, charging mold has noz~le means at its upper
end for spraying li~uid carbon dioxide into the mold to form dry
ice snow. A precompressing piston is slidably mounted in the
upper, charging mold, and normally rests in an elevated position
above the nozzle means. After the desired quantity of dry ice
snow has been formed in the charging molcl, and with the shutter
1~ member in a closed position, the pr~compressing'piston is driven
downwaxdly by a hydraulic actuator to precompress the dry ice snow
into a loosely compacted charge block~ Carbon dioxide gas released
during this precompression step can escape the charging mold ~
-through discharge ports provided in the upper end thereof, and in
2Q addition the shutter member and the lower portion of the charging
mold are preferably made from a porous metal that will allow
trapped carbon dioxide gas under pressure to escape therethrough.
Af~er the dry ice snow has been precompressed into a
charge block, the shutter assembly is opened and the precompressed
2S charge block enters the lower, press mold. The precompressing
piston is preferably designed to be movable downwardl,y, to assist
movement of the precompressed charge block of dry ice snow into the
press mold. The shutter assembly then moves into a position closing
the upper end of the press mold, and a press piston contained within
the press mold is moved upwardly by a hydraulic actuator to form a
brick-shaped block of dry ice from the charge.
~ ~86~'3
-- 6
The shutter assembl~ includes a shutter that i5 utilized
to close off the opening between the two molds, and a shutter
extension that pro,ects forwardly from the shutter. The upper
surfaces of the shutter and the shutter extension are continuous,
but the undersurface o~ the extension is recessed and open at the
front. The hydraulic actua-tor arrangement for moving the shutter and
the shutter extension is effective -to shift the assembly to
three different positions. In a first, shut-down position, the
shutter assembly is fully advanced and completely closes both the
~O outlet of the upper mold and th~ inlet of the lower mold. This
posltion is utilized for both the precompression and the final
compression steps. In the second, or full open position, both the
shutter and the shutter ex-tension are fully retracted and are
free of the inlet and outlet openings, so that the two molds are
.5 in full communication. Finally, in an intermediate, inlet open
position, the sh~tter assembly is moved so that the shutter extension
closes the outlet opening of the upper mold, but the recess there-
under is open to -the inlet opening of the lower mold.
In opera-tion, the shutter assembly is moved into the
'O inlet open position after -the final compression step is complete
in the lower mold, and the press piston i9 then operated to
elevate the brick-shaped block of dry ice into the shutter recess.
The shutter assembly is then operated to move it into the fully
advanced shut-down posit1on, and in the process the shutter is
'5 effective to remove the just produced block of dry lce away frcm
the apparatus and onto z transfer mechanism. Thus, automatic
operation of the apparatus is achie~Jed.
The apparatus of the present invention offers several
advantages over prior machines for producing blocks of dry ice,
including ~he following:
-- 7
1. By u-~ilizing the shutter assembly, in cooperatlon
- with the press piston, to au~oma~ically remove the
just produced block of dry ice from the apparatus,
the need to have one or more movable molds of the
type shown in the cited British patent is eliminated.
Instead, the molds can be fixed to a supporting
frame, and the whole apparatus is mechanically less
complicated and expensiue.
2. By precompressing the dry ice snow in the upper
mold, certain advantages are obtained. First,
because the char~e block entering the lower mold
has already been partialIy compressed, the stro]se
distance of the pxess piston and the overall
length of -the lower, press mold can be considerably
shorter than in apparatus like that shown in the
British patent. This reduces the overall height
of the apparatus and its wei~ht, making the re-
sultant machine less expensive and more adaptable
to different woxk locations. Secondly, utilization
of the precompressing plston to move the precom-
pressed charge block of dry ice snow into the lower
mold removes effectively all of the dry ice snow
from the upper mold, which helps assure the uniform
production of brick-shaped blocks of dry ice. Third,
the precompressing action and the dropping of the
precompressed charge into the lower mold helps the
escape of carbon dloxide gas, thus improving the
efficiency of the finaI compression step and the
quality of the resultant dry ice blocks.
3 ~6~85.C~
~- 8 -
3. The use of a breathing, porous material
for the shutter and portions of the molds
allows the escape of carbon dioxide gas
to occur during the two compressing steps,
which reduces the required capacity of the
hydraulic actuators t improves the overall
efficiency of the apparatus, and improves
the ~uality of the produced dry ice blocks.
It is the principle advantage of the present
invention, at least in preferred forms~ that it can
provide apparatus for making brick-shaped blocks of dry
ice of high quality, in an automatic manner and with a
minimum of expense and labor.
It is another advantage of the invention, at
least in preferred forms, that it can provide an apparatus
for making dry ice blocks from carbon dioxide gas, wherein
normally trapped carbon dioxide gas is allowed to escape
from the compressed dry ice snow so as to improve the
efficiency of the apparatus and the quality o the result-
ant dry ice.
It is a further advantage of the invention, at
least in preferred forms, that it can provide an apparatus
for making dry ice blocks from carbon dioxide gas wherein
two molds are provided, and which is designed so that both
molds can be mounted s~a~ionary upon a supporting frame.
It is yet another advatnage of the invention, at
least in preferred forms, that it can provide an apparatus
for making dry ice blocks that is o~ minimum height and
weight, and which is economical to construct and maintainO
~.
~6
- 8a -
Other advantages o~ the present invention will
become readily apparent from the following Description of
the Preferred Embodiments, when taken in ~onjunction with -
the attached drawings.
.
` I ~6168~9
g
BRIEF DESCRIPTION OF THE DRAWINGS
- FIG. 1 ts an exploded perspective view of key components
of the apparatus of the present invention, with some of the com-
ponents being shown in phantom lines, and illustrates the basic
relationship of those key components to each other;
FIG. 2 is side elevational view of the apparatus of
the inven~ion, partly in section, and with some components
partially broken away to show the construction thereof;
FIG. 3 is a front elevational view of the apparatus
of FIG. 2;
FIG. 4 is an explanatory schematic view illustrating
the production steps fro making dry ice blocks with the present
apparatus, and includes steps I through V, connected by flow
arrowsi
FIG. 5 is an enlarged, elevational view of a modified
upper mold, wherein the lower portion of the mold is made from
a porous metal to facilitate the escape o~ carbon dioxide gas;
FIG. 6 is a schemat~c diagram illustrating the
operating sequence of the components of the invention, including
the various hydraulic actuators and switches that cooperate to
provide automatic operation;
FIG. 7 is an elevational view of the prior art device
discussed earlier herei.n, showing the apparatus in a stage where
a dry ice block has just been compressed; and
FIG. 8 is a further elevational view of the prior art
device of FIG. 7, showing the apparatus with the press cylinder
lowered for removal of the completed dry ice block,
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in particular to FIGS. 1-3 of the drawings,
the present apparatus includes an upper, charging mold 1 and a
lower, press mold 2 disposed in vertical alignment, the two molds
B8 .~
- 10 - `
1 and 2 being separated by a shut-ter space 3 and being secured to
a machine frame F ~.hat includes as its main components a pair of
spaced vertical plates 17. The upper mold 1 has an outlet opening
4 at the lower end thereof, and the lower mold 2 has an inlet opening
5 at its upper end, both openings Eacing the shutter space 3 and
being in alignment with each other.
A shutter 6 is mounted for forward and backward
horizontal movement in the shutter space 3, and is connected to
hydraulic actuators 25 that are in turn attached to the frame F.
0 The shutter 6 has an extension 7 on the front edge thereof, the top
surfaces of the shutter 6 and the extension 7 presenting a continuous
surface, and a recess being formed beneath the extension 7 and the
front face 28 of the shutter 6, the recess being open on the front
and bot~om thereoE.
A precompression piston 8 is slldably received within
the upper, charging mold 1, and is connected with the shaft of a
hydraulic actua-tor 9 that is attached to the -frarne F. The lower,
press mold slidably receives a press piston 10, con~ected to the
shaft of a hydrau~ic actuator 11 that is effective to raise and
~0 lower the press piston. Mounted on opposite sides of the
rectangular upper, charging mold 1 are charging ducts 12, the
outlets 14 of the ducts 12 belng positloned below the upper end
of the mold so that the precompression piston ~ can be moved to a
pvsltion thereabove.
~5 As shown in FIG. 2, the charging duc~s 12 are arranged
at an oblique angle relative to the vertical axis of the upper mold
1, and each duct opens at its lower end 14 into the charglng mold.
As best shown in FIG. 3, the sidewalls of the retangular in cross-
section charging ducts 12 taper outwardly from top to bottom, so
that they have a continuously increasing cross-section in this
s ~(~
direction. An inJection nozzle 13 is positioned at the upper
end of each charging duct 12, and is utilized to spray or jet liquid
carbon dioxide into -the charging mold 1 to form dry ice snow.
In operation, liquid carbon dioxide is sprayed into the
upper mold 1, until the desired quantity of dry ice snow S has been
created During this step, the actuators 25 maintain the shutter
6 in a position wherein the outlet 4 is closed. Once the desired
amount of dry ice snow S has accumulated, the hydraulic actuator 9
is activated -to lower the precompression piston 8, ~hich is ef-
fective to shape the snow into a charge block 15. The actuators25 are then actuated to move the shutter 6 and its extension 7
to the fully retracted position wherein both the inlet 5 and the
outlet 4 are open, and the charge block 15 can then move by
gravity into the lower, press mold 2. Preferably, the precompression
piston 8 is further moved downwardly by the hydraulic actuator 9
to forcefully eject the charge bIock 15 from the upper mold 1, the
piston 8 also then being effective to remove essentially all the
dry ice snow from the upper charging mold.
After the charge block 15 has been placed ln the lower,
2~ press mold 2, the actuators ~5 a~e utilized to move the shutter 6
into the fully closed posi~,ion of FIG. 2. The hydraulic actuator
11 is then activated to elevate the press piston 10, which forms
the charge 15 of the dry ice snow into a brick~shaped block 16
of dry ice, the rectan~ular cross-section of the mold 2 assuring
the brick-shape. When the block 16 has been formed, the actuators
25 are again activated, this time to shift the shutter 6 to the
right in FIG. 2 so that the recess under the eY~tension ~ is paced
over the mold inlet 5.
The hydraulic actuator 11 is then further activated,
so that the press piston 10 elevates to where the top surface
thereof is level with the upper end of the press mold 2. This
~ ~B~.'3
- 12 -
places the block 1~, within the recess, and in alignment with a trans-
- fer mechanism 29 attached to the frame F. The shutter actuators 25
are then activated to move the shutter..6 to the left in FIG. 2,
so that the front surface 28 of the shutter 6 is effective to
transfer the completed block 16 of dry ice onto the trans.fer
mechanism 29; during all this time, the continuous upper surfaces
of the shutter 6 and the ext~nsion 7 have been effective to seal
the lower end outlet opening 4 of the upper, charging mold 1, so
that the next accumulation of dry ice snow in the mold 1 can occur.
When the next charge block 15 of dry ice snow has been
prepared, the shutter assembly is again shifted into its open
position, to a].low the charge 15 to enter the lower, press mold 2.
Thus, a full cycle of operation of the apparatus is completed.
The charging mold 1 and the press mold 2, as has been
noted, both have rectangular cross-sections, and the upper mold 1
is preferably made of stainless steel. The mold 1 has a plurality
of carbon dioxide vent holes 18 formed therein above the duct
openings 14, and the outlets oE these vent holes 18 open into
a discharge duct 19 that encircles the mold 1 and has a discharge
outlet ~0. The spray nozzles 13 are designed so as to produce dry
ice snow with adiabatic expansion when liquid carbon dioxide is
jetted therethrou~h, and are connected with a liquid carbon dioxide
bottle 2] by a conduit 22 and a remotely controlled valve 23.
The lower, press mold 2 is also preferably constructed
of stainless steel, and is provided with reinforcing stiffeners 24
on the exterior of its upper end that also serve as heat absorbing
fins. Because toward the end of flnal compression of the char~e
into dry ice the dry ice snow is pressed with a high pressure of
approximately 150 kg/cm2, the upper end of the press mold 2 needs
to be strong and should be reinforced. The reinforcing fin
stiffeners 24 serve this purpose.
6 8 ~ ~3
Further, when the outer circumferential surface of the
produced dry ice block 16 has been formed, it will tend to stick
b~ freezing to the inner surface of the press mold 2, making it
difficult for the press piston lO to move it into the recess
beneath the shutter extenslon 7. The reinforcing fin stiffenexs
24 alleviate this problem, by absorbing external heat which is then
applied to the lower mold 2 to warm the inner surface thereof and
break down any freezing-sticking action. It is also preferable that
` the internal surface of the lower, press mold 2 be smooth and unin-
terupted, again in part to alleviate any possible freezing-sticking
problem.
Referring now to the diagramatic presentation of FIG.
4, the operating cycle of the apparatus of thè invention is
illustrated therein. In FIG. (I~, the shutter 6 has been placed
in its fully advanced, full shutdown position, with both the
outlet 4 and the inlet 5 closed. Eurther, the precompression
piston 8 has been elevated to its withdrawn position, above the
duct openings 14 and the ports 18. Liquid carbon dioxide is
then sprayed into the charging mold l, to form dry ice snow S.
Moving no~7 to FIG. 4 (II), after the desired ~uantity
of dry ice snow S has been formed in the charging mold ], flow
from the nozzles 14 is terminated, and the hydraullc actuator 9
is actuated to move the precompression piston 8 downwardly to
form the precompressed charge 15 of dry ice snow. Then, as shown
in FIG. 4 (III), the shutter 6 and the shutter extension 7 are
fully retracted to their fully open position, and the precompressed
charge of dry ice snow 15 is dropped into the press mold 2, with
assistance rrom further lowering of the precompression piston 8.
~fi~
Moving now to FIG. ~ (IV), after the charge 15 is
- in place in the lower, press mold 2, the shu~ter 6 is advanced
to its fully forward posltion so that both the outlet 4 and the inlet
5 are closed thereby. The press piston 10 is then moved upwardly
by the hydraulic actuator 11, to form a brick-shaped block 16 of
dry ice. In parallel with this step, the charging mold 1 is again
supplied with liquid carbon dioxide through the no~zles 13, to form
another volume of dry ice snow S therein.
Finally, as shown in FIG. 5 ¢V), after formation of
.0 the dry ice block 16 is complete the shutter 6 is partially
retracted to place the shutter extension 7 over the outlet opening
4, and to position the recess formed under the extension 7 over the
inlet opening 5. The brick-shaped dry ice block 16 is then moved
upwardly into the recess by further activation of the press piston
.5 10, and then the shutter assembly is further advance to its original
position, which action places the block 16 on the transferring
mechanism 29. When the charging chamber has been sufficiently
filled with dry ice snow S, the ~ycle then begins anew, and is
repeated to continuously produce brick-shaped dry ice blocks o~
O uni.form characteristics, each cycle taking but a few minutes of
time.
As has been mentioned, it is preferable to vent any
carbon dioxide gas remaining in the dry ice snow S~ The vent
ports 18 enable considerable such venting to occur, but there
'5 remains the problem of gas ~rapped within the charge 15 under the
precompressing piston 8. To allow for the escape o~ such
trapped carbon dioxide gas, the shutter 6 is constructed of sinter-
ing metal having the property of being relatively porous to the
passage of gas, such met.als being commercially available~ The
O interior of the shutter 6 is formed with vent passages 30, to
~ ~68,~
convey away carbon dioxide gas that is passed thereinto by the
porous meta]. With this arrangement, the dry ice snow can be
efficiently precompressed into a charge 15 without undue inter-
ference from carbon dioxide ~ases present therein, and theresultant dry ice blocks 16 wil~ have a more uniform high
density and quality.
To further allow ~or the escape of carbon dioxide
gas, a modification of the upper, charging mold is shown at 1'
in FIG. 5. The lower portion 31 of the mold 1' is constructed
from the same type of sintering, porous metal as the shutter 6,
and thus also allows for escape of trapped gas. The mold l'
has ports 18' in its upper end, like those utilized on the mold 1.
It is also to be understood that the upper end of the lower,
press mold can be constructed of such porous metal, if desired,
to further enhance the removal of trapped carbon dioxide gas.
No drawing FIG. is shown for this embodlment, since it would
appear very similar to the arrangement of FIG. 5.
The adiaba~ic processes in the presen-t invention can
create problems with the materials, and the inventlon takes this into
account. It will be noted that the precompressing piston 8 and the
press piston 10 are in almost continual contact with dry ice snow,
which has a temperature of about -70C. If this temperature or
even one considerably above this leverl is transmitted to other
components of the apparatus, for example, the hydraulic actuators,
problems can occur.
If the hydraulic oil is cooled substantially, its
viscosity increases and hydraulic power devices using the oil will
lose some of their power output capability. On the other hand,
if there is thermal transmission from the hydraulic cylinders to
the precompression piston 8 or the press piston 10, heat may
cause some of the dry ice snow to sublimate into carbon dioxide
gas.
8 5 ~
- L6 -
To overcome these problems, the pistons 8 and 10 are
connected to the rods of their respective actuators so as to
minimize the transmission of heat. ;Referring now to FIG. 2, the
precompression piston 8 comprises a base plate 8a, an adiabatic
plate 8b formed from some adiabatic FRP material, and a face
plate 8c. Similarly, the press piston 10 includes a base
plate lOa, an adiabiatic plate lOb, and a face plate lOc. The
pr~sence of the adiabiatic plates 8b and lOb greatly alleviates
heat transfer problems, and preferably a similar arrangement is
utilized to isolate the shutter 6 from its hydraulic actuators
25.
The hydraulic system for the apparatus includes a
hydraulic power device 31 for supplying pressurized oil to the
actuat:ors 9, 11 and 25, the device 31 including an oil tank,
a hydraulic pump, an electric motor, and suitable control valves
and switching devices, all of conventional design. The device 31
is installed on a portion 17a of the supporting frame F, to the
rear of the press mold 2.
~ control box 32 is provided for the apparatus/ and
is mounted on the front side of the supporting frame F. The
control box 32 contai.ns sequence control circuits for controlling
the actuators 8, 11 and 25, through directional control solenoid
valves that control flow in conduits 33 that are connected with the
actuators, and by controlling the solenoid valve 23 in the liquid
carbon dioxide conduit 22. The control circuit is of conventional
design, and hence will not be described in detail herein. However,
an explanation of the control .sequence will now be given in
connection with the schematic drawing of FIG. 6.
8,~
The control ci.rcuit includes a number o~ limit switches,
all of which perform thelr usual function. The press actuator 11
is provided with limit switches LSl, LS2 and LS3 for detecting the
upper position, the pressing-limit position and the lower position
of the press piston 10, respectively. Similarly, the precom-
pression actuator 9 is provided with limit switches LS7 and ~S8
for detecting the retracted or standing by and the dropping or
lowered positions of the precompression piston 8, respectively.
The shutter assembly actuator 25 is provided with limit switches
LS4, LS5 and LS6 for detecting the fully open, inlet open, and
shutdown positions of the shutter 6 and the shutter extension 7,
respectively.
Referring now to FIG. 6 at the start of a cycle the
starting button of the control box 32 is pressed, and the first
occurrence is that the flow control solenoid valve 23 on the
liquid carbon dioxide conduit 22 is opened to begin the formation
of dry ice snow in the upper, charging mold 1. ~he control circuit
then actuates components in a timed sequence, controlled by the
circuit in the usual manner.
The actuator 9 i9 activated to hegin lowering of the
precompression ~#~L~e=t~ to precompress the dry ice snow and
p;Ston 8
form the charge block 15, as indicated by the reference character
a in FIG. 6, and after the shutter 6 and the shu~ter extension 7
are changed to their fully open position, as indicated in the FIG.
by the character b, the charge 15 is dropped into the press mold
2, as indicated by the character c.
~ hen, after the shutter 6 has been moved to its shut-
down position, as indicated by the reference character d ln FIG. 6,
the charge 15 is pressed to form the block 16 of dry ice by
activating the actuator 11 and elevating the press piston 10, as
~:~6~
- 18 -
shown by the reference character e. Then, during holding of
the dry ice block 16 in a standby position, as shown by the
reference character f, the shutter 6 and the shutter extension 7
are changed to their i.nlet open positions, indicated by reference
character g, after which the solid dry ice block 16 is elevated
into the shutter recess, as indicated by the refer~nce char-
acter h of FIG. 6~
During movement of the shutter 6 to its shutdown
position, the dry ice block 16 is pushed forward by the pushing
face 28 of the shutter, as shown by the reference character i.
In parallel with the process steps e through i, the:liquid carbon
dioxide for forming the next charge 15 is supplied into the
changing mold 1, by keeping open the solenoid valve 23.
Obviously, many modifications and varlations of the
present invention are possible.
