U.S. patent application number 13/590687 was filed with the patent office on 2012-12-13 for system and method for manufacturing fatty acid based material products with an injection molding process.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to Edward Francis Burress, Terry Alan Smith.
Application Number | 20120315347 13/590687 |
Document ID | / |
Family ID | 42036829 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120315347 |
Kind Code |
A1 |
Smith; Terry Alan ; et
al. |
December 13, 2012 |
System And Method For Manufacturing Fatty Acid Based Material
Products With An Injection Molding Process
Abstract
A system manufactures molded fatty acid based material products
by forming a fatty acid based material paste and injecting the
paste into a mold having internal cavities. The system includes a
controller that regulates heat generated by a movable member in the
barrel of an injection molding machine and a cooling jacket on the
exterior of the barrel to enable nearly melted fatty acid material
and nearly solid melted fatty acid material to mix within the
barrel to form a paste that is ejected into a mold to form the
products. The paste enables the products to form a skin that is
less susceptible to shrinkage during cooling so the product is
formed without voids that cause breakage or mar aesthetic
appearances of the product.
Inventors: |
Smith; Terry Alan; (Aurora,
OR) ; Burress; Edward Francis; (West Linn,
OR) |
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
42036829 |
Appl. No.: |
13/590687 |
Filed: |
August 21, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12236431 |
Sep 23, 2008 |
8246891 |
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13590687 |
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12235174 |
Sep 22, 2008 |
8038424 |
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12236431 |
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Current U.S.
Class: |
425/144 |
Current CPC
Class: |
B29C 45/78 20130101;
B29L 2031/767 20130101; B29C 2945/76381 20130101; B29C 2945/7604
20130101; B29C 2945/76933 20130101; B29C 2945/76454 20130101; B29C
2945/76538 20130101; B29C 45/47 20130101; B29C 2945/76193
20130101 |
Class at
Publication: |
425/144 |
International
Class: |
B29C 45/78 20060101
B29C045/78 |
Claims
1. A system for manufacturing molded food products comprising: a
volumetric container having a wall that encloses a space, the wall
having an inlet and an outlet, the inlet being configured to
receive fatty acid based material pieces that are solid at room
temperature and feed the material pieces into the container; a
cooling member located within the volumetric container that removes
heat from the wall; a heated member located within the volumetric
container at a position separated from the wall of the volumetric
container, the heated member being configured to heat the fatty
acid based material within the volumetric container to a first
temperature that is less than a melting temperature of the fatty
acid based material to form a paste; an ejection member configured
to force a portion of the fatty acid based material paste from the
volumetric container through the outlet of the volumetric
container; a mold having at least two separable shells that form
product cavities, the mold being in fluid communication with the
outlet of the volumetric container to receive the fatty acid based
material paste, the at least two separable shells having gates that
are sized to prevent elevation of the fatty acid based material
paste above the first temperature, and the at least two separable
shells having a temperature that enables the fatty acid based
material paste to form a skin upon contact with an internal surface
of one of the at least two separable shells; and a controller
coupled to the heated member, the cooling member, and the ejection
member, the controller being configured to keep the heated member
in a first temperature range that maintains fatty acid based
material at the first temperature proximate the heated member, to
keep the cooling member in a second temperature range that
maintains fatty acid based material at a second temperature
proximate the cooling member, and to energize the ejection member
to form the fatty acid based material paste proximate the outlet of
the volumetric container and eject the portion of the fatty acid
based material paste from the volumetric container through the
outlet.
2. The system of claim 1 further comprising: a second cooling
member proximate the mold, the second cooling member being
maintained at a temperature that enables the fatty acid based
material paste injected into the mold to form the skin upon contact
with the internal surface of at least one shell of the at least two
separable shells.
3. The system of claim 5 wherein at least one shell of the mold is
coupled to a stationary frame, and at least one other shell of the
mold is coupled to a movable frame; and the system further
comprises: a second actuator coupled to the movable frame; and the
controller is operatively connected to the second actuator and the
controller being further configured to energize the second actuator
selectively to move the movable frame and the at least one other
shell of the mold into and out of mating with the at least one
shell of the mold to enable the at least two shells of the mold to
separate and release molded products from the mold.
4. The system of claim 1 wherein the movable member is a screw
extruder.
5. The system of claim 1 wherein the movable member is a ram
injector.
6. A system for manufacturing fatty acid based material comprising:
an injection molding machine having a barrel with a wall
surrounding an internal cavity, the barrel having an outlet; a
cooling jacket mounted on an exterior of the barrel; a movable
member located within the internal cavity of the barrel; a heater
located within the movable member; an actuator coupled to the
movable member; and a controller coupled to the heater within the
movable member, the cooling jacket, and the actuator, the
controller being configured to regulate the heater to maintain the
movable member within a temperature range in which liquid fatty
acid based material proximate the movable member remains in a
liquid or near liquid state, to operate the cooling jacket to
maintain the wall of the barrel in a temperature range in which
fatty acid based material proximate the wall of the barrel remains
in a solid or near solid state, and to energize the actuator to
cause the movable member to mix the liquid or near liquid fatty
acid based material proximate the movable member with the solid or
near solid fatty acid based material proximate the wall of the
barrel to form a fatty acid based material paste.
7. The system of claim 6, the controller being further configured
to energize the actuator to move the movable member and eject fatty
acid based material paste through the outlet of the barrel.
8. The system of claim 6 further comprising: a mold having at least
two separable shells that form product cavities, the mold being in
fluid communication with the outlet of the barrel to receive the
fatty acid based material paste, the at least two separable shells
having gates that are sized to prevent elevation of the fatty acid
based material paste above the first temperature; and a second heat
exchanger proximate the mold to maintain the mold at a temperature
that enables the fatty acid based material paste injected into the
mold to form a skin upon contact with an internal surface of one of
the at least two separable shells of the mold.
9. The system of claim 8 wherein at least one shell of the mold is
coupled to a frame of the injection molding machine, and at least
one other shell of the mold is coupled to a movable frame; and the
system further comprises: a second actuator coupled to the movable
frame; and the controller being operatively connected to the second
actuator and the controller being further configured to energize
the second actuator selectively to move the movable frame and the
at least one other shell of the mold into and out of mating with
the at least one shell of the mold to enable the at least two
shells of the mold to separate and release molded products from the
mold.
10. The system of claim 5 wherein the movable member is a screw
extruder.
11. The system of claim 5 wherein the movable member is a ram
injector.
Description
CLAIM OF PRIORITY
[0001] This application is a divisional application of and claims
priority to U.S. patent application having Ser. No. 12/236,431,
which was filed on Sep. 23, 2008, and is entitled "System And
Method For Manufacturing Fatty Acid Based Material Products With An
Injection Molding Process," and which will issue as U.S. Pat. No.
8,246,891 on Aug. 21, 2012, and to U.S. patent application having
Ser. No. 12/235,174, which was filed on Sep. 22, 2008, and is
entitled "System And Method For Manufacturing Fatty Acid Based
Material Products With An Injection Molding Process."
TECHNICAL FIELD
[0002] This disclosure relates generally to processing of fatty
acid type materials, and, more particularly, to the manufacture of
molded fatty acid food products.
BACKGROUND
[0003] Molding materials with a base of fatty acid-like properties
produces mixed results. Most materials have a significant density
difference between their solid state and the liquid state typically
injected into molds. Chocolate products, for example, generally are
prepared industrially by conching a ground chocolate ingredient
mixture paste at a temperature of from about 50 degrees to about 85
degrees C. and by tempering the conched chocolate to provide a
fluid, pourable mass. Viscosity considerations require that the
fluid tempered chocolate generally be directed immediately to a
molding operation for final product preparation. Although cooling
can be carried out during tempering, correct tempering procedures
generally require that the chocolate have a temperature on the
order of from about 27 degrees C. to about 35 degrees C., depending
upon the chocolate composition and character. In addition, when
using tempered chocolate in a molding operation, temperature
control of the mold also is important, and in general, heating and
cooling operations are required.
[0004] If the mold temperature is less than the temperature of the
tempered fluid chocolate being injected into the mold, the
chocolate adjacent the mold surface tends to contract at a rate
different from the remainder of the chocolate in the mold which, in
turn, tends to result in rough product surfaces and/or de-molding
problems and/or poor gloss. On the other hand, if the mold is too
hot, the chocolate may lose its temper at least partially, which
tends to result in poor contraction during cooling and/or in
producing a product having a poor surface-finish. Thus, the molding
operation generally requires heating a mold to a temperature which
substantially corresponds to that of the tempered fluid
chocolate.
[0005] After filling the mold cavity, the mold is cooled to set the
chocolate. Generally, a cooling tunnel assembly or a multi-tier
cooler, as known in the art, are used for this cooling. A properly
set and glossy product typically requires cooling the mold and
chocolate to a temperature on the order of from 10 degrees C. to 20
degrees C. The rate of cooling is also important, not only because
of cooling contraction considerations, but also because an at least
initial gradual controlled cooling should be employed so that the
final product does not exhibit or tend to develop, prematurely, fat
bloom. Thus, a cooling cycle time on the order of from about 20
minutes to about 30 minutes is typically required for a properly
set product. This time frame limits the amount of production, while
the equipment and energy necessary for thermal control increases
the expense of product manufacture. Numerous materials other than
chocolate, such as cheese, soaps, various candies and
confectionaries, as well as intermediate fabrication processes that
use wax of various forms, and the like, exhibit similar behaviors
and have similar process requirements.
SUMMARY
[0006] A method has been developed that enables fatty acid-like
material products, such as those made from chocolate, to be formed
without requiring the mold to be held at the temperature of the
material being injected into the mold and then being cooled
thereafter. The method forms a fatty acid based material paste and
injects the fatty acid based material paste into a mold having
internal cavities that are cooled to a temperature that is less
than the fatty acid based material paste being injected into the
mold. The method includes generating a fatty acid based material
paste, cooling a mold having at least two separable shells that
form product cavities to a temperature that is less than the fatty
acid based material paste, injecting a portion of the fatty acid
based material paste under pressure into the mold, and separating
the shells of the mold to release products from the product
cavities. The paste may be formed by a variety of techniques,
including heating a first quantity of solid fatty acid based
material particulates to a temperature at which the fatty acid
based material particulates reach a liquid state and then mixing
the first quantity of fatty acid based material particulates with a
second quantity of fatty acid based material particulates in or
near a solid state to form a paste. This paste is suitable for
injection into a mold that has been cooled to a temperature that is
less than the fatty acid based material paste.
[0007] This method of product manufacture may be used with an
injection molding machine to form a system for manufacturing molded
food products. The system includes an injection molding machine
having a barrel in which a heated member is located, the barrel
having an outlet. The system also includes a cooling jacket mounted
on an exterior of the barrel, a movable member located within the
barrel, a heater located within the movable member, an actuator
coupled to the movable member, and a controller coupled to the
heater, the cooling jacket, and the actuator, the controller being
configured to regulate the heater to maintain the movable member
within a temperature range in which liquid fatty acid based
material remains in a liquid or near liquid state, to operate the
cooling jacket to maintain the barrel in a temperature range in
which fatty acid based material remains in a solid or near solid
state, and to energize the actuator to cause the movable member to
mix the liquid or near liquid fatty acid based material proximate
the movable member with the solid or near solid fatty acid based
material proximate the barrel to form a fatty acid based material
paste.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing aspects and other features of a molded fatty
acid based material product manufacturing system and method are
explained in the following description, taken in connection with
the accompanying drawings.
[0009] FIG. 1 is a diagram of an injection molding machine in which
molded fatty acid based material products may be manufactured.
[0010] FIG. 2 is a flow diagram of a process that may be
implemented by configuring the controller of the machine in FIG. 1
to perform the process.
[0011] FIG. 3 illustrates an alternative method for manufacturing
the paste that is injected into the mold of FIG. 1.
[0012] FIG. 4 illustrates another alternative method for
manufacturing the paste that is injected into the mold of FIG.
1.
DETAILED DESCRIPTION
[0013] FIG. 1 depicts an injection molding machine 10 in which the
method of manufacturing molded fatty acid based material products,
which is described below, may be implemented. The term fatty acid
based material is intended to include all fatty acid and similar
materials known in the various food, cosmetic, soap, and wax
industries. This range of fatty acid based materials is hereafter
described with reference to a chocolate or fatty acid food material
for simplicity. The custom made injection molding machine 10 has a
barrel 12 with a diameter of 80 mm and a length l of approximately
2.5 m. Solid food pieces, such as chocolate buttons, bits, or
pastilles, may be supplied to the injection-molding apparatus 10
through a feeder 18. As discussed in more detail below, the paste
may be generated elsewhere and then fed to the injection molding
machine. If solid food pieces are provided through the feeder 18,
the food pieces may be produced by any known technique. The size of
the pieces can range from more than 12 mm to about 1 microns. The
small size of the pieces provides greater surface area for heating
to enable the pieces to respond to heating and cooling quickly.
While smaller pieces are desirable for this reason, manufacture,
storage, and transport of the pieces may influence the optimal size
for the food material used in a particular environment.
[0014] A temperature profile of the barrel 12 is maintained by one
or more cooling jackets 14, which are grouped into independently
controlled zones along the barrel 12, including along a barrel head
12a and a nozzle portion 16. The cooling jackets include fluid
passageways that enable a coolant to flow through the jacket. The
coolant absorbs heat from the barrel and the warmed fluid is passed
through a heat exchanger 44 to remove the heat from the fluid. The
fluid may then be re-circulated through the jacket to continue the
cooling of the barrel. The fluid may be, for example, an oil or an
ethylene glycol. A rotary actuator or drive 20 turns a retractable
screw 22 within the barrel 12. The screw 22 is also hollow to
enable heaters (not shown) to be placed within the screw. Selective
activation of the heaters controls the temperature of the screw. In
one injection molding machine, the screw 22 has a diameter of 25
mm.
[0015] The heaters or other thermal controlling elements within the
screw 22 and the cooling jackets 14 are coupled to a controller 30.
The controller is a processor and related input/output circuitry
with volatile and non-volatile memory. Programmed instructions are
stored in a portion of the memory for execution by the processor to
control the injection molding process. These instructions may be
programmed in a known manner to configure the controller to monitor
the temperature of the barrel, the screw, and other areas of the
machine and to regulate these temperatures by controlling the
heaters within the screw and the flow of coolant through the
cooling jackets. Additionally, the controller is coupled to the
drive 20 to move the screw within the barrel 12 in a programmed
manner. Thus, the ability of the machine 10 to form solid products
depends upon the configuration of the controller by the programming
instructions stored in the memory of the controller. In one
envisioned application for food products, the nominal target
temperature is in a range of about 27 degrees C. to about 95
degrees C. for the screw and the nominal target temperature is in a
range of about 15 degrees C. to about 25 degrees C. for the
barrel.
[0016] If all of the food pieces within the barrel reach the
melting temperature for the food being processed, the fatty food
fails to respond to the rotation of the screw to move forward to
the nozzle 16 of the barrel 12. On the other hand, if all of the
food pieces remain in a solid state, the fatty food fails to
achieve sufficient flow characteristics to enable injection of the
material from the barrel into a mold coupled to the nozzle 16. To
enable the food to acquire a consistency that enables movement
within the barrel and injection into the mold, the controller has
been configured through programming instructions to heat the screw
to a temperature that maintains the food pieces proximate the
heated member in a liquid state and to regulate the barrel
temperature at a level that keeps the food pieces proximate the
barrel in a solid state. The liquid food proximate the screw
enables the screw to rotate freely. The screw rotation acts to mix
the melted fatty food with the solid fatty food between the screw
and the barrel to form a paste. The paste also responds to the
rotation of the screw by being moved forward towards the nozzle. A
non-return valve 36 prevents the paste from squeezing backwards
into the barrel portion 12 during injection. Thus, the controller
maintains the screw 22 at a temperature that generates a sufficient
amount of melted fatty food to form a paste when mixed with the
solid fatty food in the barrel by the rotation of the screw.
[0017] As used herein, the term "paste" refers to a material in a
state between liquid and solid, which may be described as
semi-liquid or semi-solid. These two descriptions, semi-liquid and
semi-solid, are synonymous. The liquid state for the material being
processed is a state in which the material is pourable and conforms
to the shape of a sharp cornered container as the material is
poured into the container. The solid state refers to the state in
which the material retains a given three dimensional shape having a
non-supported square cross-section projection with a length/width
ratio of 5 for a time period of 24 hours under uniform
environmental conditions. This description can apply to "flaccid"
materials, such as cheese, where the initial shape may include
droop, but does not increase its droop under the conditions stated
above. The width referenced is the widest cross-section acting to
resist droop due to gravity and would be uniform over the length of
cross-section. Some fatty acid based materials over some portion of
the temperature range at which the described paste state exists may
also be described as a slurry since a portion of the paste is
liquid and another portion of the paste is solid or nearly solid.
The reader should appreciate that the waxy nature of such material
may undergo a state change from solid to liquid over a wide
temperature range that is extended in comparison to other more
familiar substances, such as water becoming ice when chilled, steam
when heated, or solder transitioning from a nominally malleable
solid state to liquid almost immediately after supplying sufficient
heat. Different constituents in the fatty food melt at different
temperatures so the material is not easily induced into a
homogeneous paste state by simply altering its temperature.
Therefore, fatty acid food and other fatty acid based materials may
appear to be solid when nearly so and liquid when not fully so.
[0018] This understanding of material states related to temperature
should aid the reader in seeing that churning or mixing fatty food
that is liquid with fatty food that is solid results in a
temperature change of that fatty food mixture and yield a more
uniform paste consistency over a fairly short period of time. The
process of producing this paste state can occur by mixing fully
liquid material with fully solid material in appropriate
proportions based on churning or mixing effectiveness for an
adequate time, allowing the cooler mass to warm and the warmer mass
to cool. A paste state may also be attained by mixing fatty food
that has not fully reached the liquid state with fatty food that is
not fully solid, to generate any combination of fully or partially
liquid fatty food mixed with fully or nearly fatty food, depending
upon the amount of time the two states or near-states are mixed and
the effectiveness of the mixing. The mixing or churning of the
range of material states is affected by shear tendencies of the
different states and these tendencies are affected by temperature
and mass of the different material states confined between heated
and cooled members or structures of the injection molding machine
or press. Holding material at a temperature intermediate the solid
and liquid states for an extended period of time may allow the
material to become a usable paste, but this method of producing
paste may not be practical in high volume production scenarios.
[0019] The press barrel 12 is maintained at a temperature that
prevents all of the solid fatty food in the barrel from being
melted so a paste can be formed. Although the barrel may be
described as cooled, this term is used in a relative sense. Thus,
the "cooler" temperature of the barrel is defined as being below
the fatty food melt temperature so this surface may in fact, at
times, be heated and, at other times, be cooled to prevent it from
becoming too hot. The rotation of the screw 22 also mechanically
transports the paste to the nozzle 16 so the controller can
energize the reciprocating actuator and pressurize a portion of the
paste to eject a shot of paste from the nozzle 16 into the mold 24.
Once the paste shot has been injected, the rotary drive 20 rotates
the screw 22 to continue making the paste and to transport a
portion of the paste forward to the nozzle. The rotary drive
portion 20 is controlled by the controller to transport each shot
through the barrel portion 12 in regular cycles at a set velocity
to enable the time that each shot spends in the different
temperature zones of the barrel 12 to be precisely controlled. This
precision enables the consistency of each shot to be reproducibly
controlled. A drive or actuator may rotate a screw for mixing
and/or feeding fatty food paste or may accomplish those functions
with a linear motion, such as reciprocating motion of a screw or a
piston, plunger, or ram. Combinations of rotary and linear motion
may be used with a screw or ram within a molding machine. An
actuator may also move an ejection member that is independent of
the barrel and an internal feed device or conveyor, which may be a
ram, screw, or some conveyor combination.
[0020] The mold 24 is a mold having internal cavities that are
coupled together by runners, as known in the art, although other
types of molds may be used. As shown in FIG. 1, a clamp 40 moves
the two sections 24a, 24b of the mold 24 towards and away from one
another. The applied clamp force is dependent on the size and the
number of the products to be molded. In one envisioned embodiment,
a clamp force of about 25 tons is applied to the mold. The mold
also includes an inlet that is configured for mating with the
nozzle 16 of the barrel 12. The inlet enables a paste shot ejected
from the nozzle to enter the mold to form items within the internal
cavities of the mold.
[0021] The fatty acid based material paste enters the mold cavities
through gates that are fed either by the nozzle of the barrel or,
if multiple cavities are within a mold, runners extending from the
nozzle. Because the fatty acid based material paste is thicker than
materials typically injected into molds and a goal of the process
is to prevent fatty acid based material temperatures from elevating
excessively, larger than typical gates are desired. Small gates
require higher injection forces that increase the velocity and
friction of the material as it enters the cavity. These factors
heat the material and may attenuate the benefit of injecting fatty
acid based material paste into a mold with a paste consistency.
Gate size is influenced by the timing of the injection cycle and
the volume and shape of the cavity or cavities to be filled. In one
envisioned embodiment, the gate size has a diameter of
approximately 5 mm.
[0022] The mold 24 also includes one or more fluid passageways that
are not in fluid communication with the internal cavities. These
passageways may be coupled to a cooling system that pumps a coolant
through the passageways to remove heat from the mold. The coolant
may be an oil or ethylene glycol and the coolant is circulated
through a heat exchanger 44 to remove heat from the coolant and
renew the ability of the coolant to maintain the temperature of the
mold below the liquid state maintaining temperature. Thus, a paste
shot entering the mold forms a skin as a portion of the shot
contacts a wall of an internal cavity of the mold. The skin helps
seal the fatty acid based material product so it is relatively
impervious to moisture after the fatty acid based material product
is released from the mold. Additionally, the skin is sufficiently
thick that the mold may be separated by the controller operating
the clamp relatively quickly after the injection of the paste shot
into the mold without deformation of the fatty acid based material
product. The skin and the amount of paste in a shot are adequate to
enable the fatty acid based material internal to the skin to cool
without shrinkage or breakage of the skin. In one envisioned
embodiment, the mold is maintained within a temperature range of
about -5 degrees C. to about 5 degrees C. Depending upon material
properties and mold dwell times, this temperature range may extend
from about -60 degrees C. to over 20 degrees C. Because moisture in
the air may produce ice particles at the lower temperatures, the
process is better performed in a relatively dry environment.
[0023] A method 100 that may be implemented by programmed
instructions executed by the controller is shown in FIG. 2. In
general, the method generate a paste from solid fatty acid based
material, injects a portion of the paste under pressure into a
cooled mold having at least two separable shells that form product
cavities, and separates the shells of the mold to release molded
fatty acid based material products from the product cavities. The
injection pressure used in one application was nominally about 5
Bar during the initial and mid-phase of fill and was increased to
about 40 Bar to ensure the mold was fully packed at the end of the
fill cycle. In one envisioned embodiment, solid fatty food pieces
are loaded from a source, such as a hopper of an injection molding
machine, into the barrel of the machine (block 104). In other
possible embodiments, the fatty acid based material may be melted
to form a liquid state. This liquid fatty acid based material may
be fed into the injection molding machine. In the injection molding
machine, the screw of the machine is heated to a temperature within
a range that converts solid fatty acid based material to a liquid
or near liquid state or that maintains that state (block 108).
Additionally, the wall of the barrel is regulated to a temperature
within a range that converts liquid fatty acid based material to a
solid or maintains solid fatty acid based material in a solid state
(block 110). The screw is rotated to mix the melted fatty food
proximate the screw with the solid fatty food proximate the barrel
(block 114). The mixing of the melted fatty food and the solid
fatty food forms a paste that is transported by the rotating screw
to the nozzle of the barrel (block 118). The screw is then
retracted to enable a portion of the shot to enter the nozzle
(block 124) and then the screw is driven forward to eject a shot of
the paste from the nozzle of the barrel (block 128). The shot
enters a mold that is cooled to a temperature that enables a
portion of the shot that contacts the walls of the internal
cavities to form a skin for a food product (block 132). The mold is
separated (block 136) to enable the food products to fall from the
mold. The mold is then closed (block 140) and the process continues
(block 104).
[0024] The injection molding machine and method of operation
described above requires an injection molding machine to heat and
to cool the material within the barrel of the injection molding
machine. The cooling is performed by circulating a heat absorbing
medium about the barrel to enable the barrel to be maintained in a
temperature range that causes the material to exist in a solid
state proximate the barrel. The heating is performed by circulating
a heated media in the interior of a hollow screw, operating a
cartridge heater within the screw, or by regulating current flow in
a resistive heater associated with the screw. By providing material
in both a solid state and a liquid state within the injection
molding machine, a paste can be formed having a consistency that
enables the screw to transport the paste forward to an outlet and
eject the paste into a cooled mold. The temperature of the mold
enables the paste to flow through the gates and passageways of the
mold and, upon contact with a wall of an internal cavity, form a
skin. This skin provides an exterior for the product with
relatively few surface defects. The skin also enables the remaining
paste to fill the interior of the skin without voids while
maintaining desirable aesthetics. Upon release of the product from
the mold, the skin is sufficiently solid that little or no breakage
occurs in the ensuing handling or occasional mishandling and the
continued cooling is sufficiently uniform that dimples, cracks, and
other defects are less likely to form than with other previously
known mold methods for ink stick formation.
[0025] The injection molding machine and method described above may
be used to form solid objects from fatty acid based material
materials that are capable of being both liquid and solid. For
example, chocolate, taffy-like candies, and cheese can be melted to
form a liquid and cooled to form a solid. Consequently, such fatty
acid based material products may be fed to an injection molding
machine as either a liquid or a solid and treated by the screw and
barrel to form a fatty acid based material paste. This paste may
then be transported by the screw to the ejection port and shot into
a cooled mold for formation of a solid object, such as a chocolate
bar or cheese block. Other products, for example, candle wax,
soaps, and cosmetics, may also be molded with this method.
[0026] In another envisioned embodiment of the injection molding
machine useful for manufacturing fatty acid based material objects,
the paste may be produced outside of the injection molding machine.
The paste may be made, for example, by mixing a predetermined
quantity of the material in a solid state with a predetermined
quantity of the material in the liquid state to form the paste. The
paste may then be pumped or gravity fed into the injection molding
machine. The barrel and screw of the injection molding machine are
regulated by the controller to remain within a temperature range
that keeps liquid material proximate the screw and solid material
proximate the barrel. The paste material is transported to the
ejection port and shot into the cooled mold as described
before.
[0027] Other methods may be used to obtained material pastes. For
example, the described material paste consistency can be attained
by a method in which a large mass of material is held in a
volumetric container, such as container 304 shown in FIG. 3, which
is placed in a heating chamber 308, such as an oven. A controller
312 is coupled to temperature sensors (not shown) in the heating
chamber so the controller can regulate the chamber temperature at
an appropriate temperature for a sufficient time to obtain
uniformity in the paste without melting material in the container.
FIG. 4 illustrates another example in which solidified material is
forced into inlet 404 of a barrel 400 and urged through
constricting passages 408 and 412. The passages are brought to
elevated temperatures by a heating element 416 to heat the
material. The convergence of the materials before exiting through
the outlet 420 mixes the heated flows for formation of the paste.
Again, heating element 416 may be coupled to a controller for
regulation of the temperature of the passageways.
[0028] It will be appreciated that various of the above-disclosed
and other features, and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Various presently unforeseen or unanticipated
alternatives, modifications, variations, or improvements therein
may be subsequently made by those skilled in the art, which are
also intended to be encompassed by the following claims.
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