U.S. patent application number 12/327857 was filed with the patent office on 2010-06-10 for preparation of building material for solid freeform fabrication.
This patent application is currently assigned to Objet Geometries Ltd.. Invention is credited to Eliahu M. Kritchman, Guy Menchik, Eduardo Napadensky.
Application Number | 20100140852 12/327857 |
Document ID | / |
Family ID | 42230194 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100140852 |
Kind Code |
A1 |
Kritchman; Eliahu M. ; et
al. |
June 10, 2010 |
PREPARATION OF BUILDING MATERIAL FOR SOLID FREEFORM FABRICATION
Abstract
A method suitable for solid freeform fabrication is disclosed.
The method comprises mixing respective amounts of a plurality of
materials such as to provide a building material characterized by
at least one attribute, and using the building material for
fabricating a three-dimensional object.
Inventors: |
Kritchman; Eliahu M.; (Tel
Aviv, IL) ; Napadensky; Eduardo; (Natania, IL)
; Menchik; Guy; (RaAnana, IL) |
Correspondence
Address: |
MARTIN D. MOYNIHAN d/b/a PRTSI, INC.
P.O. BOX 16446
ARLINGTON
VA
22215
US
|
Assignee: |
Objet Geometries Ltd.
Rechovot
IL
|
Family ID: |
42230194 |
Appl. No.: |
12/327857 |
Filed: |
December 4, 2008 |
Current U.S.
Class: |
264/494 ;
366/69 |
Current CPC
Class: |
B29C 48/16 20190201;
B29C 48/17 20190201; B33Y 50/02 20141201; B33Y 30/00 20141201; B29C
64/343 20170801; B33Y 70/00 20141201; B29C 64/112 20170801; B29C
64/386 20170801; B29C 64/314 20170801; B29C 48/21 20190201 |
Class at
Publication: |
264/494 ;
366/69 |
International
Class: |
B29C 35/08 20060101
B29C035/08 |
Claims
1. A method of solid free form fabrication of an object,
comprising: (a) mixing respective amounts of a plurality of
materials such as to provide a building material characterized by
at least one predetermined attribute of combination; and (b) using
said building material for fabricating a three-dimensional object;
said steps (a) and (b) being performed in the same facility.
2. The method of claim 1, wherein said step (b) is performed less
than 24 hours after said step (a).
3. The method of claim 1, wherein said steps (a) and (b) are
performed by the same individual or group of individuals.
4. The method of claim 1, wherein said materials comprise a base
material and at least one additive material being able to produce a
predetermined attribute when mixed with said base material.
5. The method of claim 1, further comprising employing at least one
procedure selected from the group consisting of polymerization, UV
curing, thermal curing, UV post-curing and thermal post-curing.
6. The method of claim 1, wherein said building material is a UV
curable composition.
7. The method of claim 1, wherein said building material at least
partially solidifies upon exposure to radiation selected from the
group comprising electromagnetic radiation and electron beam
radiation.
8. The method of claim 1, wherein one of said plurality of
materials comprises meth/acrylic functional groups and another one
of said plurality of materials comprises mercaptopriopionate
functional groups.
9. The method of claim 1, wherein one of said plurality of
materials comprises a component containing hydroxyl functional
groups and another one of said plurality of materials comprises a
component containing an isocyanate functional group.
10. The method of claim 1, wherein said building material has a
shelf life which is shorter than 200 days.
11. The method of claim 1, wherein said building material has a
shelf life which is shorter than the shelf life of each of said
plurality of materials before mixing.
12. The method of claim 1, wherein said using said building
material for fabricating said three-dimensional object comprises
loading said building material to a solid freeform fabrication
apparatus having a user interface and utilizing said user interface
for feeding information on said respective amounts and/or said at
least one predetermined attribute of combination.
13. The method of claim 12, further comprising calculating printing
parameters according to said respective amounts and feeding
information on said printing parameters to said user interface.
14. The method of claim 1, wherein said mixing comprises operating
a preparation apparatus which comprises: an input unit, for
inputting said at least one attribute; a control unit, configured
to transmit data pertaining to said amounts, said control unit
being supplemented with an algorithm for determining said amounts;
a supply unit, operatively associated with reservoirs of said
plurality of materials and being controllable by said control unit
to supply a respective amount of each material according to said
data; and a container, configured for receiving said plurality of
materials.
15. The method of claim 14, wherein said preparation apparatus
comprises a mixer, configured for receiving said plurality of
materials and for mixing said materials.
16. The method of claim 1, wherein said mixing comprises adding an
additive material to a container containing a base material,
followed by shaking the container.
17. The method of claim 16, wherein said adding said additive
comprises using a syringe to inject said additive into said
container.
18. The method of claim 16, wherein said container is loaded into a
solid freeform fabrication apparatus.
19. The method of claim 18 wherein said container comprises a
computer readable and/or writeable medium mounted on said container
and being capable of storing respective amounts and/or at least one
attribute of the materials it contains, and said solid freeform
apparatus comprises a reading and/or writing functionality
configured to read and/or write data from said computer readable
medium.
20. Apparatus for preparing a building material for solid freeform
fabrication, the apparatus comprising: an input unit, for inputting
at least one attribute of the building material; a control unit,
configured to transmit data pertaining to respective amounts of a
plurality of different materials according to said at least one
attribute, said control unit being supplemented with an algorithm
for determining said amounts; a supply unit, operatively associated
with reservoirs of said plurality of materials and being
controllable by said control unit to supply a respective amount of
materials according to said data; and a container, configured for
receiving said plurality of materials.
21. The apparatus of claim 20, wherein said materials comprise a
base modeling material and a plurality of additive materials, each
additive being able to produce at least one attribute when mixed
with said base modeling material.
22. The apparatus of claim 20, further comprising a mixer,
configured for receiving said materials and for mixing said
materials thereby to provide a building material characterized by
said at least one attribute.
23. The apparatus of claim 22, wherein said mixer is external to
said apparatus and is configured for supplying said container with
building material.
24. The apparatus of claim 20, further comprising a computer
readable and/or writeable medium mounted on said container and
being capable of storing said respective amounts and/or said at
least one attribute and/or printing parameters of the materials
received.
25. The apparatus of claim 20, further comprising at least one
attribute measuring device, configured for measuring at least one
attribute of a material.
26. A system for solid freeform fabrication, comprising a
preparation apparatus, for preparing a building material
characterized by at least one attribute, and a solid freeform
fabrication apparatus, for fabricating a three-dimensional object
using said building material, wherein said preparation apparatus is
designed and constructed for mixing respective amounts of a
plurality of materials according to said at least one attribute,
such as to provide said building material.
27. The system of claim 26, wherein said plurality of materials
comprises a base modeling material and a plurality of additive
materials able to produce a desired attribute in the base modeling
material when the materials are mixed.
28. The system of claim 26, wherein said preparation apparatus
comprises: an input unit, for inputting said at least one
attribute; a control unit, configured to transmit data pertaining
to said amounts, said control unit being supplemented with an
algorithm for determining said amounts; a supply unit, operatively
associated with reservoirs of said plurality of materials and being
controllable by said control unit to supply a respective amount of
each material according to said data; and a mixer, configured for
receiving said plurality of materials and for mixing said materials
thereby to provide said building material.
29. The system of claim 28, wherein said supply unit comprises: a
plurality of conduits, each being in fluid communication with a
reservoir of one material, and having a flow control device
controllable by said control unit to enable and disable flow of
material in said conduit; a container for receiving materials
flowing in said plurality of conduits; and at least one
amount-measuring device, designed and constructed to measure
amounts of materials flowing in said plurality of conduits.
30. The system of claim 26, wherein said preparation apparatus is
operable to mix said respective amounts of said plurality of
materials, generally contemporaneously with said fabricating of
said three-dimensional object.
31. The system of claim 29, wherein said preparation apparatus
further comprises a computer readable medium mounted on said
container and being capable of storing said respective amounts
and/or said at least one attribute.
32. The system of claim 31, wherein said solid freeform fabrication
apparatus comprises a reading and/or writing functionality
configured to read and/or write data from said computer readable
medium.
Description
FIELD AND BACKGROUND OF THE INVENTION
[0001] The present invention relates to solid freeform fabrication
(SFF) and, more particularly, to apparatus, system and method for
the preparation of building material for solid freeform
fabrication.
[0002] Solid freeform fabrication processes are defined as
processes in which objects are constructed in layers utilizing a
computer model of the objects. The layers are deposited or formed
by a suitable device which receives signals from a computer using,
e.g., a computer aided design (CAD) software.
[0003] Solid freeform fabrication is typically used in
design-related fields where it is used for visualization,
demonstration and mechanical prototyping. Thus, solid freeform
fabrication facilitates rapid fabrication of functioning prototypes
with minimal investment in tooling and labor. Such rapid
prototyping shortens the product development cycle and improves the
design process by providing rapid and effective feedback to the
designer. Solid freeform fabrication can also be used for rapid
fabrication of non-functional parts, e.g., for the purpose of
assessing various aspects of a design such as aesthetics, fit,
assembly and the like. Additionally, solid freeform fabrication
techniques have been proven to be useful in the fields of medicine,
where expected outcomes are modeled prior to performing procedures.
It is recognized that many other areas can benefit from rapid
prototyping technology, including, without limitation, the fields
of architecture, dentistry and plastic surgery where the
visualization of a particular design and/or function is useful.
[0004] Various solid freeform fabrication techniques exist. One
such technique, known as three-dimensional printing is disclosed
in, e.g., U.S. Pat. Nos. 6,259,962, 6,569,373, 6,658,314,
6,850,334, 6,863,859, 7,183,335, 7,209,797, 7,225,045 and 7,300,619
and U.S. Published Application Nos. 20040207124, 20050104241 and
20070179656, the contents of which are hereby incorporated by
reference. In this technique, building materials are dispensed from
a printing head having a set of nozzles to deposit layers on a
supporting structure. Depending on the building materials, the
layers are then cured using a suitable curing device. The building
materials may include modeling materials and support materials,
which form the object and the support constructions supporting the
object as it is being built.
[0005] U.S. Pat. No. 5,149,548 discloses apparatus for
three-dimensional printing of an object from a two-part curable
material and a setting material. The setting material is
encapsulated in microcapsules and the apparatus uniformly disperses
the microcapsules into the two-part curable material. A rupturing
unit ruptures the microcapsules so as to cure the curable material.
The two-part curable materials may be of different kinds and/or
colors.
[0006] Also of interest is U.S. Pat. No. 6,007,318 which discloses
a printer which forms three-dimensional objects from a powder by
selectively applying a binder liquid to the powder. The binders may
be used with or include dyes which may be combined to create a
plurality of colors. Binder liquid and dyes may be deposited at
selected locations of the powder.
SUMMARY OF THE INVENTION
[0007] It has been recognized that in many applications there is a
need to build objects using building materials with different
properties. This is the case, for example, when different objects
need to be built, each one using a different color or using a
building material having a different mechanical property. Since the
number of potentially desirable colors or mechanical properties,
for example, is almost limitless, there is no practical possibility
to manufacture and/or produce such a large number of different
building materials.
[0008] Use of separate materials in different colors or kinds
limits the number of colors or kinds available for use and would
necessitate storage of a number of separate containers of material;
thus being both limiting and inconvenient for the end-user.
[0009] In addition, even limiting the number of building materials
to a limited set would result in the need to stock a large number
of building materials, with all the logistic and capital
implications of such stock.
[0010] Another problem that needs to be addressed when storing
different modeling materials, is the shelf life of the various
materials. Different building materials may have different shelf
lives, according to their specific compositions.
[0011] With respect to the application of a binder liquid to
powder, it was found that while offering a wider range of colors,
the jetting of binders and/or dyes onto powder is inherently
problematic due to dispersion or spreading of powder upon impact of
the jetted materials. In addition, the amount of liquid jetted onto
the powder must be limited relative to the amount of powder so as
not to negatively affect the formation of the part. Therefore the
amount of dye being used would by necessity also have to be
limited, irrelevant of the final color desired to be attained.
[0012] According to an aspect of some embodiments of the present
invention there is provided a method of solid free form fabrication
of an object, comprising: (a) mixing respective amounts of a
plurality of materials such as to provide a building material
characterized by at least one predetermined attribute of
combination; and (b) using the building material for fabricating a
three-dimensional object; the steps (a) and (b) being performed in
the same facility.
[0013] According to some embodiments of the invention the step (b)
is performed less than 24 hours after the step (a).
[0014] According to some embodiments of the invention the steps (a)
and (b) are performed by the same individual or group of
individuals.
[0015] According to some embodiments of the invention the materials
comprise a base material and at least one additive material being
able to produce a predetermined attribute when mixed with the base
material.
[0016] According to some embodiments of the present invention the
base material comprises a polymerizable material and the additive
material comprises a substance able to affect at least one of the
following properties of the base material: reactivity, color,
rheology of the liquid state composition and mechanical properties
of the resulting solid material.
[0017] According to some embodiments of the invention the base
material comprises substances comprising hydroxyl functions
[0018] According to some embodiments of the invention the additive
material comprises isocyanate functions.
[0019] According to some embodiments of the invention the method
further comprising employing at least one procedure selected from
the group consisting of polymerization, UV curing, thermal curing,
UV post-curing and thermal post-curing.
[0020] According to some embodiments of the invention the building
material is a UV curable composition.
[0021] According to some embodiments of the invention the building
material at least partially solidifies upon exposure to radiation
selected from the group comprising electromagnetic radiation and
electron beam radiation.
[0022] According to some embodiments of the present invention the
electromagnetic radiation is characterized by a frequency range
selected from the group consisting of UV frequency range, Infra-Red
frequency range and Visible light frequency range.
[0023] According to some embodiments of the invention one of the
plurality of materials comprises meth/acrylic functional groups and
another one of the plurality of materials comprises
mercaptopriopionate functional groups.
[0024] According to some embodiments of the invention one of the
plurality of materials comprises a component containing hydroxyl
functional groups and another one of the plurality of materials
comprises a component containing an isocyanate functional
group.
[0025] According to some embodiments of the invention at least two
materials are characterized by different post-hardening attributes
selected from the group consisting of color, hardness, elasticity,
translucency, density, electrical conductivity, magnetization and
any collection thereof.
[0026] According to some embodiments of the invention at least one
material of the plurality of material is a building material
additive.
[0027] According to some embodiments of the invention the building
material additive comprises photoinitiator.
[0028] According to some embodiments of the invention the building
material has a shelf life which is shorter than 200 days
[0029] According to some embodiments of the invention the building
material has a shelf life which is shorter than the shelf life of
each of the plurality of materials before mixing.
[0030] According to some embodiments of the invention the using the
building material for fabricating the three-dimensional object
comprises loading the building material to a solid freeform
fabrication apparatus having a user interface and utilizing the
user interface for feeding information on the respective amounts
and/or the at least one predetermined attribute of combination.
[0031] According to some embodiments of the invention the method
further comprising calculating printing parameters according to the
respective amounts and feeding information on the printing
parameters to the user interface.
[0032] According to some embodiments of the invention the mixing
comprises operating a preparation apparatus which comprises: an
input unit, for inputting the at least one attribute; a control
unit, configured to transmit data pertaining to the amounts, the
control unit being supplemented with an algorithm for determining
the amounts; a supply unit, operatively associated with reservoirs
of the plurality of materials and being controllable by the control
unit to supply a respective amount of each material according to
the data; and a container, configured for receiving the plurality
of materials.
[0033] According to some embodiments of the invention the
preparation apparatus comprises a mixer, configured for receiving
the plurality of materials and for mixing the materials
[0034] According to some embodiments of the invention the mixing
comprises operating at least one attribute measuring device,
configured for measuring at least one attribute of a sample of at
least one of the plurality of materials.
[0035] According to some embodiments of the invention the flow
control device comprises at least one element selected from the
group consisting of a valve and a pump.
[0036] According to some embodiments of the invention the
preparation apparatus further comprises a computer readable medium
mounted on the container and being capable of storing the
respective amounts and/or the at least one predetermined attribute
of combination.
[0037] According to some embodiments of the invention the using the
building material for fabricating the three-dimensional object
comprises loading the container to a solid freeform fabrication
apparatus having a reading and/or writing functionality configured
to read and/or write data from the computer readable medium.
[0038] According to some embodiments of the invention the solid
freeform fabrication apparatus is operable to mix the plurality of
materials, and the mixing comprises operating the solid freeform
fabrication so as to mix the materials.
[0039] According to some embodiments of the invention the mixing
comprises adding an additive material to a container containing a
base material, followed by shaking the container.
[0040] According to some embodiments of the invention the adding
the additive comprises using a syringe to inject the additive into
the container.
[0041] According to some embodiments of the invention the container
is loaded into a solid freeform fabrication apparatus.
[0042] According to some embodiments of the present invention the
container comprises a computer readable and/or writeable medium
mounted on the container and being capable of storing respective
amounts and/or at least one attribute of the materials it contains,
and the solid freeform apparatus comprises a reading and/or writing
functionality configured to read and/or write data from the
computer readable medium.
[0043] According to an aspect of some embodiments of the present
invention there is provided apparatus for preparing a building
material for solid freeform fabrication, the apparatus comprising:
an input unit, for inputting at least one attribute of the building
material; a control unit, configured to transmit data pertaining to
respective amounts of a plurality of different materials according
to the at least one attribute, the control unit being supplemented
with an algorithm for determining the amounts; a supply unit,
operatively associated with reservoirs of the plurality of
materials and being controllable by the control unit to supply a
respective amount of materials according to the data; and a
container, configured for receiving the plurality of materials.
[0044] According to some embodiments of the invention the materials
comprise a base modeling material and a plurality of additive
materials, each additive being able to produce at least one
attribute when mixed with the base modeling material.
[0045] According to some embodiments of the invention the apparatus
further comprising a mixer, configured for receiving the materials
and for mixing the materials thereby to provide a building material
characterized by the at least one attribute.
[0046] According to some embodiments of the invention the mixer is
external to the apparatus and is configured for supplying the
container with building material.
[0047] According to some embodiments of the invention the building
material is characterized by a post-hardening attribute selected
from the group consisting of color, hardness, elasticity,
translucency, density, electrical conductivity, magnetization and
any collection thereof.
[0048] According to some embodiments of the invention the additive
comprises photoinitiator.
[0049] According to some embodiments of the invention the supply
unit comprises: a plurality of conduits, each being in fluid
communication with a reservoir of one material and having a flow
control device controllable by the control unit to enable and
disable flow of material in the conduit; and at least one
amount-measuring device, designed and constructed to measure
amounts of materials flowing in the plurality of conduits.
[0050] According to some embodiments of the invention the apparatus
further comprising a computer readable and/or writeable medium
mounted on the container and being capable of storing the
respective amounts and/or the at least one attribute and/or
printing parameters of the materials received.
[0051] According to some embodiments of the invention the apparatus
further comprising at least one attribute measuring device,
configured for measuring at least one attribute of a material.
[0052] According to an aspect of some embodiments of the present
invention there is provided a system for solid freeform
fabrication, comprising a preparation apparatus, for preparing a
building material characterized by at least one attribute, and a
solid freeform fabrication apparatus, for fabricating a
three-dimensional object using the building material, wherein the
preparation apparatus is designed and constructed for mixing
respective amounts of a plurality of materials according to the at
least one attribute, such as to provide the building material.
[0053] According to some embodiments of the invention the plurality
of materials comprises a base modeling material and a plurality of
additive materials able to produce a desired attribute in the base
modeling material when the materials are mixed.
[0054] According to some embodiments of the invention each material
is characterized by a different attribute selected from the group
consisting of color, hardness, elasticity, translucency,
polymerizability, viscosity, density, electrical conductivity,
magnetization and any collection thereof.
[0055] According to some embodiments of the invention the building
materials is characterized by a post-hardening attribute selected
from the group consisting of color, hardness, elasticity,
translucency, density, electrical conductivity, magnetization and
any collection thereof.
[0056] According to some embodiments of the invention at least one
additive material comprises photoinitiator.
[0057] According to some embodiments of the invention the
preparation apparatus comprises: an input unit, for inputting the
at least one attribute; a control unit, configured to transmit data
pertaining to the amounts, the control unit being supplemented with
an algorithm for determining the amounts; a supply unit,
operatively associated with reservoirs of the plurality of
materials and being controllable by the control unit to supply a
respective amount of each material according to the data; and a
mixer, configured for receiving the plurality of materials and for
mixing the materials thereby to provide the building material.
[0058] According to some embodiments of the invention the supply
unit comprises: a plurality of conduits, each being in fluid
communication with a reservoir of one material, and having a flow
control device controllable by the control unit to enable and
disable flow of material in the conduit; a container for receiving
materials flowing in the plurality of conduits; and at least one
amount-measuring device, designed and constructed to measure
amounts of materials flowing in the plurality of conduits.
[0059] According to some embodiments of the invention the
preparation apparatus is operable to mix the respective amounts of
the plurality of materials, generally contemporaneously with the
fabricating of the three-dimensional object.
[0060] According to some embodiments of the invention the
preparation apparatus further comprises a computer readable medium
mounted on the container and being capable of storing the
respective amounts and/or the at least one attribute.
[0061] According to some embodiments of the invention the solid
freeform fabrication apparatus comprises a reading and/or writing
functionality configured to read and/or write data from the
computer readable medium.
[0062] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. In
case of conflict, the patent specification, including definitions,
will control. In addition, the materials, methods, and examples are
illustrative only and not intended to be limiting.
[0063] Implementation of the method and system of the present
invention involves performing or completing selected tasks or steps
manually, automatically, or a combination thereof. Moreover,
according to actual instrumentation and equipment of preferred
embodiments of the method and system of the present invention,
several selected steps could be implemented by hardware or by
software on any operating system of any firmware or a combination
thereof. For example, as hardware, selected steps of the invention
could be implemented as a chip or a circuit. As software, selected
steps of the invention could be implemented as a plurality of
software instructions being executed by a computer using any
suitable operating system. In any case, selected steps of the
method and system of the invention could be described as being
performed by a data processor, such as a computing platform for
executing a plurality of instructions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] The invention is herein described, by way of example only,
with reference to the accompanying drawings. With specific
reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of
illustrative discussion of the preferred embodiments of the present
invention only, and are presented in the cause of providing what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention, the description taken with the
drawings making apparent to those skilled in the art how the
several forms of the invention may be embodied in practice.
[0065] In the drawings:
[0066] FIG. 1 is a flowchart diagram describing a method for solid
freeform fabrication of an object, according to various exemplary
embodiments of the present invention;
[0067] FIG. 2a is a schematic illustration of a system for solid
freeform fabrication, according to various exemplary embodiments of
the present invention;
[0068] FIG. 2b is a schematic illustration of a preparation
apparatus, according to various exemplary embodiments of the
present invention; and
[0069] FIG. 2c is a schematic illustration of a solid free form
fabrication apparatus, according to various exemplary embodiments
of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0070] The present embodiments comprise a method, apparatus and
system which can be used for solid freeform fabrication.
Specifically, the present embodiments can be used for preparing
building material having one or more specific, predefined
attributes and for fabricating a three-dimensional object using the
prepared material.
[0071] The principles and operation of a method, apparatus and
system according to the present embodiments may be better
understood with reference to the drawings and accompanying
descriptions.
[0072] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting.
[0073] According to a preferred embodiment of the present
invention, there is provided a method for solid freeform
fabrication (SFF) comprising preparing a modeling material by:
selecting an attribute or property desired to characterize the
modeling material composition, selecting modeling material(s) and
optionally modeling material additives, the combination of which
may impart said desired attribute or property to the modeling
material, mixing the modeling materials and additive/s, and
fabricating a three-dimensional object with the mixed modeling
material using SFF apparatus.
[0074] According to another preferred embodiment of the present
invention, the method comprises mixing modeling material(s) and/or
optionally material additive/s, wherein the mixed material is
characterized by having a shorter shelf life than that of the
modeling material prior to mixing. Because of the shortened shelf
life, mixing should preferably be carried out close to or shortly
before the modeling material mix is used for printing or building.
The shelf life of the mixed material may be less than 200 days, or
less than 150 days, or less than 100 days, or less than 50 days, or
less than 30 days, or less than 14 days, or less than 7 days.
[0075] An example of the above is addition of an additive with a
short shelf life to the modeling material, wherein the lifetime of
the mix is, as a result, shorter than the shelf life of the
modeling material. In some embodiments of the present invention the
additive is a small amount of material. This allows transporting
the additive to the user shortly before use, according to user
demand. In some embodiments of the present invention the modeling
material and the additive separately have long shelf-lives, but
when mixed together, the shelf life of the resulting mixed material
is significantly shortened.
[0076] Thus there is provided a method for SFF comprising preparing
a modeling material by: selecting an attribute or property desired
to characterize the modeling material composition, selecting a
modeling material and a modeling material additive or additives
which will impart the desired attribute or property to the modeling
material, mixing the modeling material and additive and fabricating
a three-dimensional object with the modified modeling material
using a SFF apparatus.
[0077] Different modeling material additives impart different
properties to a single modeling material. Therefore the ability to
use different modeling material additives in different quantities,
as required, enables the obtainment of numerous different modeling
materials, each having different properties, preferably from a
single base modeling material.
[0078] In some embodiments of the present invention a single
modeling material is used as a base material to which may be added
different additives to achieve different properties, thus enabling
exploitation of the shelf-life of the base modeling material and/or
enabling the preparation of a number of different modeling
materials out of a single modeling material. In addition, the range
of properties which may be imparted to the base modeling material
is greater than has been available with known technologies to date.
The method according to some embodiments of the present invention
has significant logistical advantages in that (a) less modeling
material needs to be purchased, since instead of purchasing a large
number of different modeling materials, according to some
embodiments of the invention single base modeling materials may
used and additives need only be purchased in small amounts, if and
when necessary, (b) less storage place is necessary, for the same
reasons, and (c) there is less material waste due to (i)
preservation of the shelf-life of the materials and (ii) less
materials and smaller amounts of materials, purchased if and when
necessary, increasing the likelihood that all materials purchased
will be used, instead of larger amounts of separate modeling
materials needing to be purchased and stored, some or part of which
may remain unused and eventually discarded.
[0079] Therefore, instead of purchasing and storing numerous
different modeling materials, the user that uses the method of the
present embodiments can purchase and store only one base material
and a few additives, and order additives in small amounts only when
needed.
[0080] Referring now to the drawings, FIG. 1 is a flowchart diagram
of a method suitable for solid freeform fabrication of an object.
It is to be understood that unless otherwise defined, the method
steps described hereinbelow can be executed either simultaneously
or sequentially in many combinations or orders of execution.
Specifically, the ordering of the flowchart diagrams is not to be
considered as limiting. For example, two or more method steps,
appearing in the following description or in the flowchart diagrams
in a particular order, can be executed in a different order (e.g.,
a reverse order) or substantially simultaneously. Additionally,
several method steps described below are optional and may not be
executed.
[0081] The method can be used for fabricating a three-dimensional
object using any known solid freeform fabrication technique,
including, without limitation, three-dimensional printing.
[0082] The method begins at step 200 and continues to step 201 in
which two or more materials are mixed to provide a building
material characterized by at least one predetermined attribute. The
predetermined attribute can be selected by the operator of the
solid freeform fabrication apparatus used to fabricate the object.
The mixing can be carried out using a mixing apparatus which may be
part of the apparatus or external to it. A required quantity of one
material may be poured into a container containing another material
or, for example, injected into it. Alternately, one material may be
mixed with another within the apparatus, before or in the course of
building. The respective amounts and types of materials are
selected so as to provide a building material (e.g., a modified
modeling material) with one or more predetermined attributes. When
one or more of the building materials is toxic or hazardous, such
mixing within the apparatus maintains the safety of the user, e.g.,
by preventing skin contact or inhalation.
[0083] Each material preferably differs from all other materials by
one or more attributes. The term "attribute" encompasses both the
type of attribute and its specific value. For example, two or more
materials may be building materials of different colors whose
mixture or combination forms a different building material of a
specific color which is a combination of the different colors.
Other distinguishing attributes which are contemplated, include,
but are not limited to, hardness, elasticity, translucency,
polymerizability, viscosity, density, electrical conductivity,
magnetization and any collection of two or more of such attributes.
A distinguishing attribute can either correspond to the material
prior to its hardening (pre-hardening attributes) or after
hardening (post-hardening attributes).
[0084] One or more of the materials can be building material
additives (e.g., colorants, curing agents such as initiators,
conductivity control agents, charge control agents, magnetic
additives, etc.) which are selected to provide the mixture with the
desired attribute. An additive can be characterized as a material
which is usually only required to be added to the base material in
relatively small amounts. For example the volume of the additive
can be 50% of the bulk or less Other amounts of additives may be
required, depending on the property or attribute desired and/or its
desired intensity. One advantage of using additives is that the
mixing vessel can be the very same vessel that holds the bulk
modeling material. In this embodiment the additive is added to the
container containing the bulk modeling material. Individual
building materials may not necessarily be ready for use in building
without first being mixed with other materials. For example, they
may not be formulated for use in three-dimensional building. As an
example, a material intended for use in building a
three-dimensional object may lack a curing agent (e.g., initiator),
and only after such agent is added to the material, is it ready for
use in SFF. This is particularly useful, e.g., for overcoming the
limitations of a relatively short shelf-life of the modeling
material, where its shelf life is shortened after and/or due to
being mixed with the curing agent.
[0085] According to a preferred embodiment of the present invention
the method continues to step 202 in which the building material is
loaded into a solid freeform fabrication apparatus. A preferred
type of fabrication apparatus is a three-dimensional printing
apparatus, such as an ink-jet printing apparatus, for example, the
apparatus disclosed in, e.g., U.S. Pat. Nos. 6,259,962, 6,569,373,
6,658,314, 6,850,334, 7,183,335, 7,209,797 and 7,225,045, and U.S.
Application Publication Nos. 20060127153 and 20070179656, all
assigned to the common assignee of the present invention and fully
incorporated herein by reference. For example, a solid freeform
fabrication apparatus according to the teachings of U.S.
Application Publication No. 20060127153 can be used, in which case
the apparatus can have one or more material containing
cartridges.
[0086] In various exemplary embodiments of the invention the mixing
is performed shortly before the loading step. In one embodiment,
the mixing is carried out less than 24 hours, more preferably less
than 12 hours, more preferably less than 6 hours, more preferably
less than 3 hours, say about 1 hour or less before loading. Both
mixing and loading are preferably performed in the same facility,
i.e., on site, optionally by the same individual or group of
individuals, e.g., the operator/s of the solid freeform fabrication
apparatus. The advantage of mixing the materials shortly before
loading is that it reduces the length of interaction between the
materials. This is particularly useful when the shelf-life of each
material is longer than the shelf-life of the mixture. For example,
when one material is an additive (e.g., a hardening additive), it
is typically desired to shorten the time of interaction between the
additive and the bulk.
[0087] The advantage of performing the mixing and loading on site,
is that it enables a more accurate selection of the relative
amounts of the materials. Unlike the common situation in which the
user purchases a previously prepared mixture, and hence is forced
to select from a discrete set of mix ratios, the present
embodiments practically facilitate a continuum of mix ratios,
because the user is in a position to determine and prepare the
mixture himself.
[0088] When the mixing is performed in a mixing container which is
compatible with the loading station of the fabrication apparatus,
the entire mixing container with the building material, i.e., mixed
building material can be loaded to the fabrication apparatus, e.g.
a loadable cartridge. Alternatively, the building material can be
transferred, manually or automatically, to a loadable container
which can then be loaded into the loading station of the
fabrication apparatus.
[0089] Optionally and preferably, the method continues to step 203
in which data pertaining to the respective amounts of materials
and/or the attribute(s) of the building material are fed to the
fabrication apparatus. The feeding can be done manually using a
user-interface (e.g., a keyboard, a touch screen, etc.).
Alternatively, the loadable container can be supplemented with a
computer readable medium containing the data, in which case the
fabrication apparatus automatically reads the data from the
medium.
[0090] The fabrication apparatus preferably comprises data
processing means, such as a computer supplemented with a suitable
three-dimensional fabrication algorithm which receives the data and
calculates the optimal fabrication parameters, according to the
amount of each material in the mix. For example, if the injection
rates of two or more materials differ, the expected injection rate
of the mix is a combination of the individual rates of the mix
component, taking into account the relative proportion of the
components. After the injection rate of the mix is computed, the
algorithm determines the layer thickness according to which the
tray moves from layer to layer. A similar example is the
irradiation intensity used for curing. Knowing the required
irradiation power of the mix ingredients and the relative
proportions of the components enables computation of the required
irradiation power of the mix.
[0091] The method proceeds to step 204 in which a three-dimensional
object is printed.
[0092] The method ends at step 205.
[0093] Reference is now made to FIGS. 2a-c which are schematic
illustrations of a system 20 for solid freeform fabrication,
according to various exemplary embodiments of the present
invention. System 20 comprises a preparation apparatus 23, for
preparing the building material, and a solid freeform fabrication
apparatus 14, for fabricating a three-dimensional object using the
building material.
[0094] Preparation apparatus 23 prepares the building material by
mixing respective amounts of materials according to one or more
attributes selected by the user. Broadly speaking, there can be
more than one mode of operation for preparation apparatus 23. In
one such mode, preparation apparatus 23 operates generally
concurrently with fabrication apparatus 14. In this embodiment, an
initial supply of building material is preferably prepared by
apparatus 23 and used by apparatus 14 for the fabrication.
Additional amounts can be prepared by apparatus 23 while the
fabrication is in progress. In another mode, the operations of
fabrication apparatus 14 and preparation apparatus 23 are
intermittent such that in each fabrication cycle a predetermined
amount of building material is prepared by apparatus 23 and used by
apparatus 14. In an additional mode of operation, preparation
apparatus 23 prepares a sufficient amount of building material and
the fabrication process follows the preparation process.
[0095] Thus, the process of preparation can be performed
simultaneously, intermittently or serially with the process of
fabrication. Preparation apparatus 23 and fabrication apparatus 14
can be provided as separate units or they can be incorporated into
a single preparation-fabrication unit, as desired. A single
preparation-fabrication unit is particularly useful in the
embodiments in which the preparation and fabrication are
simultaneous or intermittent. Two separate units can be used in the
embodiment in which the fabrication is subsequent to the
preparation.
[0096] The principles and operations of preparation apparatus 23
are described first, with reference to FIG. 2b, and the principles
and operations of solid free form fabrication apparatus 14,
according preferred embodiments of the present invention are
described hereinafter with reference to FIG. 2c.
[0097] In various exemplary embodiments of the invention,
preparation apparatus 23 comprises an input unit 80, for inputting
the desired attribute or attributes of the building materials, a
control unit 82 which transmits data pertaining to the respective
amounts of the materials, and a supply unit 84 which supplies the
materials according to the data.
[0098] Input unit 80 preferably comprises a user interface 86 which
can be of any type known in the art, such as, but not limited to, a
keyboard, a touch screen and the like. Building material attributes
are input using interface 86 either by inputting the parameters of
the desired attributes or by selecting an attribute from a
predetermined list of attributes. For example, user interface 86
can present a color palette, a list of viscosity values, a list of
electrical properties and/or a list of magnetic properties, and the
operator can select the color, viscosity, electrical property
and/or magnetic property of the building material. Other attributes
and groups of attributes are also contemplated.
[0099] Control unit 82 is preferably supplemented with an algorithm
which receives the parameters of the desired attribute from unit 80
and determines the amounts of materials according to the desired
attribute(s), either by calculating the amounts or using a lookup
table. The algorithm can also include an interpolation procedure
for interpolating the entries of the lookup table. For example,
when it is desired to prepare a modeling material of a particular
color, each entry of the lookup table corresponds to a different
color which is defined by a set of color parameters (e.g., L*, a*,
b* values, X, Y, Z values or parameters of any other appropriate
color space), and includes the respective amounts of materials
required to prepare the specific color. The algorithm is preferably
capable of accessing an attribute database which includes the
attributes of each material and/or each combination of materials
which is presented to the user. For example, the attribute database
can be a color database including absorption and scatter spectra of
materials and various combinations thereof.
[0100] The user can select materials and material combinations
using a look up table. Such look up table may for example provide
lists, windows and/or drop down menus providing a list of
attributes, a list of materials and/or a list of material additives
and/or relative amounts of materials. The user may select for
example a desired attribute or attributes, and the table (system)
will provide a list of material and/or additive combinations which
would provide a modeling material or a mixed material having or
which would provide the desired attributes, and their relative
amounts; i.e. the relative amount of each material to be used, in
order to attain the desired attribute.
[0101] In one embodiment, the mixture is prepared by manually
adding materials to a mix container, where the relative amount of
the materials is determined using a lookup table. Adding an
additive to a modeling material can be done by injecting the
additive into the modeling material container using a syringe,
e.g., via a puncturable cap (e.g., a rubber cap) of the container.
The mixing can be performed, for example, by manually shaking the
container. When adding only a minute amount of material to another
material (such as in the case of adding additives), the container
containing the bulk of the material can play the role of the mix
container. In some embodiments, the container is the same container
that is loaded to the solid freeform fabrication apparatus, e.g., a
loadable cartridge of building material.
[0102] According to a preferred embodiment of the present invention
apparatus 23 further comprises a computer readable medium 104 which
stores, in a retrievable format, data pertaining to the respective
amounts of materials in the mix and/or the attribute/s of the
building material. Computer readable medium 104 can also store
other types of data. For example, medium 104 store information
whether or not container 98 has been used by a solid freeform
fabrication apparatus, or the number of times and/or duration for
which container 98 was in operation. Medium 104 can also store the
total amount of material in container 98 and the like. Medium 104
is in communication with unit 82 which transmits the data thereto.
Examples for computer readable media suitable for the present
embodiments include, but are not limited to, flash cards, compact
flash cards, miniature cards, battery-backed SRAM cards, disk
drives (e.g., magnetic, optical, semiconductor), CD-ROMs, floppy
disks, solid state floppy disk cards and the like.
[0103] Supply unit 84 is associated with reservoirs 88 of
materials. The materials flow, e.g., via a system of conduits 90,
from reservoirs 88 to supply unit 84. At least some of reservoirs
88 may comprise regular containers which are compatible with a
material loading station 102 in apparatus 14, i.e., the containers
may be loadable cartridges. The respective amounts of materials
received by unit 84 are preferably controlled by a flow control
device 92 which may include one or more valves, one or more pumps,
or an arrangement of valves and pumps. Device 92 communicates
directly or indirectly with control unit 82 and is optionally
configured to enable and/or disable flow of material in the
conduits. Supply unit 84 can further comprise an amount-measuring
device 94 for measuring the amount (weight and/or volume) of
materials flowing in each conduit.
[0104] The mixing of materials may be performed immediately or
shortly before deposition of the mixed or modified materials in a
layer being printed. An example of this is obtained when modeling
material is fed to a modeling material reservoir (not shown)
situated immediately near printing heads 21, and another modeling
material or additive is fed into the same reservoir, and both are
mixed together in the reservoir by a mixing mechanism. The mixed
material is then supplied directly to the inkjet printing
heads.
[0105] Preparation apparatus 23 further comprises a container 98,
which receives the materials. A mixing mechanism 100, such as, but
not limited to, a rotating element and/or a shaker, can be employed
for mixing the materials which make up the building material.
Mixing mechanism 100 can be mounted either externally to container
98, as shown in FIG. 2b, or it can be placed within container 98.
In an alternative embodiment, the mixing is performed manually, for
example, by shaking the container.
[0106] Preferably, but not obligatorily, container 98 is detachable
from apparatus 23. The use of a detachable container is generally
advantageous for maintenance purposes. In particular, a detachable
container is advantageous when apparatus 23 and 14 are separate
units. In this embodiment, container 98 is preferably compatible
with a material loading station 102 in apparatus 14 (not shown in
FIG. 2b, see FIG. 2c), i.e., the compatible container is a loadable
cartridge. Thus, once the building material (or modified modeling
material) is prepared, the operator can detach container 98 from
apparatus 23 and load it to loading station 102. Computer readable
medium 104 of apparatus 23 (in the embodiment in which such medium
is employed) can be mounted on container 98 and loading station 102
can be designed and configured to automatically retrieve the data
from medium 104.
[0107] In various exemplary embodiments of the invention apparatus
23 comprises one or more attribute measuring devices 106 which
measure one or more of the attributes of the building material, or
building material additive. Device(s) 106 can be configured to
measure intensive properties (e.g., color, viscosity, electrical
conductivity or resistivity, magnetization per unit volume,
viscosity, temperature) and/or extensive properties (e.g.,
magnetization, resistance, conductance, weight, volume, charge).
For example, in one embodiment, device 106 comprises a color meter
or a spectrophotometer in which case the absorption and scattering
spectra of the building material are measured to determine the
color of the material, in another embodiment, device 106 comprises
an ohm meter, in which case the resistance or conductance of the
material is measured to determine, e.g., the resistivity or
conductivity of the material, and in an additional embodiment,
device 106 comprises a viscometer, in which case the viscosity of
the building material is measured. Other attribute measuring
devices are not excluded from the scope of the present
invention.
[0108] The measured attributes of the building material can be used
as a feedback to control unit 82. In this embodiment, control unit
82 receives data from device 106 and determines whether or not the
measured property complies with the requirements received from
input unit 80. If there is insufficient compatibility between the
measured attributes and the attributes inputted to unit 80, control
unit 82 preferably recalculates the respective amounts and signals
supply unit 84 to add the appropriate materials to the mixture.
Unit 82 can also store the measured attribute(s) in medium 104.
[0109] FIG. 2c is a schematic illustration of solid freeform
fabrication apparatus 14 in a preferred embodiment in which the
apparatus is a three-dimensional printing apparatus.
[0110] In various exemplary embodiments of the invention apparatus
14 comprises one or more printing heads 21 having one or more
nozzle arrays 22, through which building material 24 is dispensed.
Printing heads 21 serve as layer-forming heads. Apparatus 14 can
further comprise one or more radiation sources 26, which can be,
for example, an ultraviolet or infrared lamp, other source of
electromagnetic radiation, visible light or electron beam,
depending on the building material being used. Radiation source 26
serves for curing the building material.
[0111] Printing head 21 and radiation source 26 are preferably
mounted on a frame or printing block 28 operative to reciprocally
move along a tray 30, which serves as the working surface on which
a three-dimensional object 12 is printed. According to the common
conventions, tray 30 is positioned in the X-Y plane. Tray 30 is
configured to move vertically (along the Z direction), typically
downward.
[0112] Apparatus 14 preferably comprises a controller 18 which
controls the operation of apparatus 14 to ensure that the layers
are properly formed.
[0113] Controller 18 may be located either within apparatus 14 or
it can communicate externally therewith via wire and/or wireless
communication. Controller 18 preferably comprises, or operates in
combination with, a data processor 110 which transmits building
instructions to controller 18, based on, for example, a
predetermined CAD configuration which may be converted, for
example, to a Solid Triangulated Language (STL) or a Slice (SLC)
format used by the data processor.
[0114] Supporting software in processor 110 uses computer object
data representing the desired dimensional configuration of object
12 and transmits building instructions to be executed by controller
18. Specifically, a suitable algorithm in the supporting software
creates the geometry of the object, and slices the geometry into
the desired number of layers. Each layer is preferably described in
the form of bitmaps as further detailed hereinabove or as generally
known in the art.
[0115] Apparatus 14 typically comprises motion devices which are
responsive to signals transmitted by controller 18. These motion
devices operate to establish relative translational motions between
head 21 and tray 30 both in the X-Y plane, and in the Z
direction.
[0116] Apparatus 14 preferably comprises a loading station 102 to
which a loadable container 98 filled with building material 112 is
loaded. In the embodiments in which computer readable medium 104 is
mounted on container 98, apparatus 14 is preferably capable of
retrieving data stored in medium 104 and/or writing data on medium
104. This can be achieved by any technique known in the art. For
example, loading station 102 can be provided with a connector 108,
such as a serial or parallel bus, which facilitates data transfer
to and/or from medium 104 to apparatus 14. Apparatus 14 can also
comprise a reading and/or writing functionality which is configured
to read and/or write the data from medium 104. The reading/writing
functionality can be implemented within controller 18 or within
processor 110. Alternatively, the data can be manually fed to data
processor 110 e.g., by means of a user interface 114. Based on the
data (received automatically or manually) data processor 110 can
calculate the printing parameters and transmits the parameters to
controller 18.
[0117] In various exemplary embodiments of the invention, apparatus
14 further comprises one or more leveling devices 32 which can be
manufactured as a roller 34 or a blade. Leveling device 32 serves
for straightening the newly formed layer prior to the formation of
the successive layer thereon. Leveling device 32 preferably
comprises a waste collection device 36 for collecting the excess
material generated during leveling. Waste collection device 36 may
comprise any mechanism that delivers the material to a waste tank
or waste cartridge.
[0118] Preferably, apparatus 14 comprises a sensing device 44 which
may be, for example, embedded within leveling device 32 or may be
external thereto. Sensing device 44 serves to determine whether a
collision with object 12 has occurred or is expected to occur. Such
a collision may be, for example, as a result of dispensed layers
being too thick and/or inconsistent in thickness, and/or because of
a mechanical malfunction of the printing head. Collision may also
occur as a result of material spill or faulty material dispensing
that may occur anywhere in the path of the printing head. For
example, sensing device 44 may be or include an
acceleration-sensing device, a shock sensor and the like.
[0119] According to a preferred embodiment of the present invention
apparatus 14 further comprises a cooling unit 38 for cooling object
12 and or apparatus 14. Unit 38 may comprise a blowing unit and/or
a sucking unit, for respectively cooling apparatus 14 by sucking
hot air or other substances out of apparatus 14 and/or drawing cool
air or other substances in to apparatus 14 from the
surroundings.
[0120] In use, printing head 21 moves in the X direction and
dispenses the building material in the course of its passage over
tray 30, in a predetermined configuration. The passage of head 21
is followed by the curing of the deposited material by radiation
source 26. In the reverse passage of head 21, back to its starting
point for the layer just deposited, an additional dispensing of
building material may be carried out, according to a predetermined
configuration. In the forward and/or reverse passages of head 21,
the layer thus formed may be straightened by leveling device 32,
which preferably follows the path of head 21 in its forward and/or
reverse movement.
[0121] Once head 21 returns to its starting point along the X
direction, it may move to another Y position and continue to build
the same layer by reciprocal movement along the X direction. Once
the layer is completed, tray 30 is lowered in the Z direction to a
predetermined Z level, according to the desired thickness of the
layer subsequently to be printed. The procedure is repeated to form
three-dimensional object 12 in a layer-wise manner.
[0122] In another embodiment, tray 30 may be displaced in the Z
direction between forward and reverse passages of head 21, within
the layer. Such Z displacement is carried out in order to cause
contact of the leveling device with the surface in one direction
and prevent contact in the other direction.
[0123] It is noted that the term "building material", as used
herein may include any modeling material, support material and/or
any suitable combination of materials suitable for use in the
printing of three-dimensional objects or models. Building material
may include material used to create objects, material used to
support objects being built and/or other material used in the
creation of objects, whether or not appearing in the final object.
The printing may include different types and/or combinations of
building materials. The term "Modeling material" may include
material that is specially formulated for use in SFF, for
building/printing three-dimensional objects.
[0124] The term "object" as used herein may include a structure
that includes the object or model desired to be built. Such a
structure may, for example, include modeling material alone or
modeling material with support material. The terms "support" as
used herein may include all structures that are constructed outside
the area of the object itself. Support structures may comprise
support material, modeling material and/or a combination of
materials. The terms "layer" or "slice" as used herein may include
portions of an object and/or accompanying support structures
optionally laid one above the other in the vertical (e.g., Z)
direction. The word layer may also be used to describe a
three-dimensional envelope or skin.
[0125] According to various exemplary embodiments of the present
invention, the building materials that may be used may be similar
to the materials described in the aforementioned patent and patent
applications (see, e.g., U.S. Pat. Nos. 6,259,962, 6,569,373,
6,658,314, 6,850,334, 6,863,859, 7,183,335, 7,225,045 and
7,300,619, and U.S. Application Publication Nos. 20040207124,
20070032563 and 20070179656). For example, photopolymer materials
curable by the application of electromagnetic radiation or other
materials suitable for three-dimensional object construction may be
used. The photopolymer material may be of various types, including,
for example, a photopolymer modeling material which may solidify to
form a solid layer of material upon curing, and a photopolymer
support material which may solidify, wholly or partially, or not
solidify upon curing, to provide a viscous material, a soft
gel-like or paste-like form and/or a semi-solid form, e.g., that
may be easily removed subsequent to printing. The various types of
photopolymer material may be dispensed separately or in any given
combination, according to the hardness and/or elasticity of the
object desired to be formed or any of its parts, or the support
constructions required to provide object support during
construction. Materials other than those described in the above
patents and applications may also be used.
[0126] When it is desired to use a modeling material different to
that presently in use in an SFF system, a material replacement step
(resin replacement) may be necessary prior to use of the `new`
material. In an inkjet SFF system, for example, the step comprises
replacement of containers or cartridges presently or most recently
in use with containers or cartridges holding other modeling
materials, and clearing the conduits and nozzles through which the
materials pass of remnants of the previously used materials.
[0127] In one embodiment of the invention, the building material
comprises acrylic monomers, e.g. ethoxylated bisphenol A
diacrylate, and free radical photo-initiators, e.g.,
bisacylphosphine oxide (BAPO's).
[0128] The free radical photo-initiator may be any compound that
produces a free radical on exposure to radiation such as
ultraviolet or visible radiation and thereby initiates a
polymerization reaction. Non-limiting examples of some suitable
photo-initiators include benzophenones (aromatic ketones) such as
benzophenone, methyl benzophenone, Michler's ketone and xanthones;
acylphosphine oxide type photo-initiators such as
2,4,6-trimethylbenzolydiphenyl phosphine oxide (TMPO),
2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (TEPO), and
bisacylphosphine oxides (BAPO's); benzoins and bezoin alkyl ethers
such as benzoin, benzoin methyl ether and benzoin isopropyl ether
and the like. Examples of photo-initiators are alpha-amino ketone,
marketed by Ciba Specialties Chemicals Inc. (Ciba) under the trade
name Irgacure 907, and bisacylphosphine oxide (BAPO's), marketed by
Ciba under the trade name I-819.
[0129] The free-radical photo-initiator may be used alone or in
combination with a co-initiator. Co-initiators are used with
initiators that need a second molecule to produce a radical that is
active in the UV-systems. Benzophenone is an example of a
photoinitiator that requires a second molecule, such as an amine,
to produce a curable radical. After absorbing radiation,
benzophenone reacts with a ternary amine by hydrogen abstraction,
to generate an alpha-amino radical which initiates polymerization
of acrylates. Non-limiting examples of a class of co-initiators are
alkanolamines such as triethylamine, methyldiethanolamine and
triethanolamine. In one embodiment of the present invention, the
composition suitable for building a three-dimensional object may
include a sulfur-containing component or a curable compound, which
is a sulfur-containing component. In an embodiment of the present
invention, the sulfur-containing component is beta
mercaptopropionate, mercaptoacetate, alkane thiols or any
combination thereof. The sulfur-containing component may be any
sulfur-containing component. The addition of sulfur-containing
components may significantly enhance the composition reactivity. At
levels of about 5% of sulfur-containing component a significant
reactivity enhancement is achieved. The mechanical properties of
the composition may be determined depending on the
sulfur-containing component used. An example of a sulfur-containing
component according to an embodiment of the present invention may
be trimethylolpropane tri(3-mercaptopropionate), manufactured by
BRUNO BOCK Chemische Fabrik GMBII & CO. Other suitable
substances may be used.
[0130] In some embodiments of the invention a composition for SFF
process is provided. The composition comprises a photo-initiator,
hardens quickly only upon exposure to UV or Vis (visible)
radiation, but with improved color (that is, less yellow than, for
example, FullCure 720 from Object Geometries Ltd, Israel). In some
embodiments, the requirement to harden quickly only upon exposure
to UV or Vis (visible) radiation means that in the absence of
radiation, the viscosity of the composition at the SFF working
temperature remains constant, within a limit of about 3 cps for at
least 30 days aging at 40.degree. C. The SFF working temperature is
between about 50.degree. C. and 100.degree. C.
[0131] It was found by the present inventors that adding about 5%
of a sulfur containing compound to the composition might results in
lowering the yellow color, however, this also results in poor
stability of the composition to an extent that replacing a first
cartridge of printing composition with another, that was
manufactured a few days apart of the first, might require
calibration of the printing machine.
[0132] It was also found by the inventors that using less photo
initiators results in stronger cured material.
[0133] It was surprisingly found that a minute amount of sulfur
containing compound, defined as less than 3% of the composition,
for example, 1% of the composition, is sufficient to reduce the
yellow color. The lowest concentration of sulfur-containing
additive in compositions according to the invention is optionally
between 0.1% and 0.25%.
[0134] In some embodiments, the composition includes polymerizable
components, and: (i) a reduced amount of photo-initiator, and (ii)
the minimal amount of sulfur-containing additive required to
achieve satisfactory photo curing of the composition. The term
"reduced amount" as used herein refers to an amount that would not
cure the composition satisfactorily in the absence of the
sulfur-containing additive. Satisfactory curing is curing that
provides desired results, under normal operation conditions of the
3D printer. In some embodiments, the desired results are at least
30% reactivity at the Menifa test.
[0135] In some embodiments, more than one photo-initiator is used.
For example, two photo-initiators are used, a first for appropriate
surface curing, and a second, for appropriate bulk curing of
composition. Optionally, such a mixture of photo-initiators is used
together with a sulfur-containing component.
[0136] It should be understood that the exact concentration of the
different components of the present invention are a function of the
lamp used and the exposure conditions.
[0137] In some embodiments, the composition for use in the
manufacture of the three-dimensional objects includes at least one
reactive component, at least one photo-initiator, at least one
surface-active agent and at least one stabilizer. The composition
may be formulated so as to be compatible for use with ink-jet
printers and to have a viscosity at room temperature above 50
cps.
[0138] Compositions suitable for use as a first building material,
a second building material and as a supporting material, according
to various exemplary embodiments of the present invention will now
be described.
[0139] The first building material and second building material of
the present embodiments are especially designed and formulated for
building a three-dimensional object using three-dimensional
printing. Accordingly, in accordance with an embodiment of the
present invention, the first building material and the second
building material each have a first viscosity at room temperature,
and a second viscosity compatible with ink-jet printers at a second
temperature, which may be the same or different, wherein the second
temperature is higher than room temperature, which is defined as
about 20-30.degree. C.
[0140] In one embodiment of the present invention, the first and
the second building materials are designed to have increased
viscosity at room temperature, which is defined as about
20-30.degree. C. In another embodiment, the first and second
building material have a viscosity greater than 50 cps at room
temperature. In another embodiment, the viscosity may be between 80
and 300 cps. In another embodiment, the first and the second
building material may have a viscosity of around 300 cps at room
temperature.
[0141] In one embodiment of the present invention, the first
building material and the second building material may have a
second viscosity compatible with ink-jet printing, at a second
temperature which may be higher than room temperature. In another
embodiment, a composition compatible with ink-jet printing may have
a low viscosity, for example, below 20 cps at the printing
temperature, in order to function properly in the printing process.
In another embodiment, the first building material and the second
building material, upon heating, have a viscosity preferably below
20 cps that may enable the construction of the three-dimensional
object under heat. In one embodiment of the present invention, the
temperature typically used to build the three-dimensional model of
the present embodiments is higher than 60.degree. C. In another
embodiment, the temperature may be about 85.degree. C. In one
embodiment of the present invention, the first and second building
materials may have a viscosity of 8-15 cps at a temperature greater
than 60.degree. C. In another embodiment, the first and second
building materials may have a viscosity of 11 cps at a temperature
of about 85.degree. C.
[0142] Having this viscosity, the first and second building
material in one embodiment may be distinguished from prior art
formulations designed for ink-jet printing, which have low
viscosity at room temperature, the temperature at which the
printing is normally conducted. High viscosity at room temperature
is a desirable property for three-dimensional objects, a feature
that is lacking in the prior art formulations. Of course, other
embodiments may have other viscosities.
[0143] The first building material (typically, the model material)
is a composition suitable for building a three-dimensional object.
The composition is optionally formulated to give, after curing, a
solid material. In one embodiment, curing of the composition
results in a solid material, with mechanical properties that permit
the building and handling of that three-dimensional object. In
another embodiment, curing the composition results in a solid
elastomer-like material, with mechanical properties that permit the
building and handling of the three-dimensional object.
[0144] In some embodiments, the modeling material comprises a
reactive component, a photo-initiator, and a sulfur-containing
component. Optionally, the modeling material also comprises a
surface active agent. Optionally, the modeling material is
substantially free of stabilizers, other than those originating in
the commercially available starting materials. This is sometimes a
preferred option, as some stabilizers contribute to undesired
coloration, and are inefficient in stabilizing a composition that
contains a sulfur-containing additive. In addition commercially
available raw materials already contain stabilizers.
[0145] In an exemplary embodiment, the first building material has
a first viscosity of about 50-500 cps at ambient temperature, and a
second viscosity lower than 20 cps at a temperature higher than the
ambient temperature, and the cured composition is solid.
[0146] Some optional ranges for the ambient temperature are:
between 20-30.degree. C., between 10-40.degree. C., between
15-35.degree. C., and between 20-30.degree. C.
[0147] Exemplary values of temperatures higher than ambient
include: at least 40.degree. C., at least 50.degree. C., at least
60.degree. C. and at least 70.degree. C.
[0148] Exemplary reactive components include a mono-functional
(meth)acrylic monomer, a poly-functional (meth)acrylic monomer
(that is, a monomer having two or more meth(acrylic) functional
groups), a (meth)acrylic oligomer, or any combination thereof, for
example, a combination of a mono-functional monomer and a
di-functional oligomer.
[0149] Optionally, the mono-functional acrylic monomer produce upon
curing a high Glass Transition Temperature (Tg) polymer.
Optionally, the di-functional oligomer produces upon curing a low
Glass Transition Temperature polymer. The term Glass transition
temperature (Tg) is defined as the temperature at which a polymer
changes from hard and brittle to soft and pliable material.
[0150] The Glass Transition Temperature of the polymerized
mono-functional acrylic monomer is optionally higher than
60.degree. C., optionally higher than 70.degree. C., optionally in
the range of 70-110.degree. C.
[0151] The Glass Transition Temperature of the polymerized
di-functional oligomer is optionally lower than 40.degree. C.,
optionally lower than 30.degree. C., optionally in the range of
20-30.degree. C.
[0152] In an exemplary embodiment the Glass Transition Temperature
of the polymerized mono-functional acrylic monomer is higher than
60.degree. C. and the Glass Transition Temperature of the
polymerized di-functional oligomer is lower than 40.degree. C.
[0153] In one embodiment of the present embodiments, the
composition may include at least 20% of the high Glass Transition
Temperature mono-functional monomer. In another embodiment, the
composition may include at least 30% of the high Glass Transition
Temperature mono-functional monomer. In another embodiment, the
composition may include at least 50% of the high Glass Transition
Temperature mono-functional monomer. In another embodiment, the
composition may include between 20-50% of the high Glass Transition
Temperature mono-functional monomer. In another embodiment, the
composition may include between 30-60% of the high Glass Transition
Temperature mono-functional monomer.
[0154] In one embodiment of the present embodiments, the
composition may include about 20% of the low Glass Transition
Temperature di-functional oligomers. In another embodiment, the
composition may include about 40% of the low Glass Transition
Temperature di-functional oligomers. In another embodiment, the
composition may include between 20-40% of the low Glass Transition
Temperature di-functional oligomers. In another embodiment, the
composition may include at least 20% of the low Glass Transition
Temperature di-functional oligomer. In another embodiment, the
composition may include not more than 40% of the low Glass
Transition Temperature di-functional oligomer.
[0155] In one embodiment of the present invention, the composition
may include at least 40% of the high Glass Transition Temperature
mono-functional monomers and at least 20% of the low Glass
Transition Temperature di-functional oligomer.
[0156] In one embodiment of the present invention, the composition
may include at least 20% of the high Glass Transition Temperature
mono-functional monomers and not more than 40% of the low Glass
Transition Temperature di-functional oligomer.
[0157] An (meth)acrylic monomer is a functional acrylated or
methacrylated molecule which may be, for example, esters of acrylic
acid and methacrylic acid. Monomers may be mono-functional or
multi-functional (for example, di-, tri-, tetra-functional, and
others). An example of an acrylic mono-functional monomer is
phenoxyethyl acrylate, marketed by Sartomer under the trade name
SR-339. An example of an acrylic di-functional monomer is
propoxylated (2) neopentyl glycol diacrylate, marketed by Sartomer
under the trade name SR-9003.
[0158] An (meth)acrylic oligomer is a functional acrylated or
methacrylated molecule which may be, for example, polyesters of
acrylic acid and methacrylic acid. Other examples of acrylic
oligomers are the classes of urethane acrylates and urethane
methacrylates. Urethane-acrylates are manufactured from aliphatic
or aromatic or cycloaliphatic diisocyanates or polyisocyanates and
hydroxyl-containing acrylic acid esters. An example is a
urethane-acrylate oligomer marketed by Cognis under the trade name
Photomer-6010.
[0159] A poly-functional (meth)acrylic monomer is a molecule which
may provide enhanced crosslinking density. Examples of such
molecules include Ditrimethylolpropane Tetra-acrylate (DiTMPTTA),
Pentaerythitol Tetra-acrylate (TETTA), Dipentaerythitol
Penta-acrylate (DiPEP). In one embodiment of the present invention,
the composition may further include, inter alia, a curable
component, which is a molecule having one or more epoxy
substituents, a molecule having one or more vinyl ether
substituents, vinylcaprolactam, vinylpyrolidone, or any combination
thereof. In one embodiment of the present invention, the
composition may further include, inter alia, vinylcaprolactam.
Other curable components may also be used.
[0160] The modeling material may also include a curable component
which is, for example, a molecule having one or more vinyl ether
substituents. In one embodiment of the present invention, the
concentration of component that includes a molecule having one or
more vinyl ether functional groups is in the range of 10-30%. In
another embodiment, the concentration is 15-20%. In another
embodiment, the concentration is 15%. Of course, other
concentrations, and other ranges, can be used. Conventional vinyl
ether monomers and oligomers which have at least vinyl ether group
are suitable. Examples of vinyl ethers are ethyl vinyl ether,
propyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether,
2-ethylhexyl vinyl ether, butyl vinyl ether, ethyleneglycol
monovinyl ether, diethyleneglycol divinyl ether, butane diol
divinyl ether, hexane diol divinyl ether, cyclohexane dimethanol
monovinyl ether and the like. An example of a vinyl ether for the
present embodiments is 1,4 cyclohexane dimethanol divinyl ether,
marketed by ISP under the trade name CHVE.
[0161] In one embodiment of the present invention, the curable
component of the modeling material (first building material)
includes, inter alia, an acrylic monomer, an acrylic oligomer. In
another embodiment, the curable component of the first building
material includes an acrylic component as defined hereinabove and a
molecule having one or more vinyl ether functional groups as
defined hereinabove
[0162] The photo-initiator of the first interface material and of
the second interface material may be the same or different, and is
optionally a free radical photo-initiator.
[0163] The free radical photo-initiator may be compounds that
produce a free radical on exposure to radiation such as ultraviolet
or visible radiation and thereby initiates a polymerization
reaction. Non-limiting examples of some suitable photo-initiators
include benzophenones (aromatic ketones) such as benzophenone,
methyl benzophenone; acylphosphine oxide type photo-initiators such
as 2,4,6-trimethylbenzolydiphenyl phosphine oxide (TMPO),
2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (TEPO); benzoins
and bezoin alkyl ethers such as benzoin, benzoin methyl ether and
benzoin isopropyl ether and the like. Examples of photo-initiators
are alpha-amino ketone, marketed by Ciba Specialties Chemicals Inc.
(Ciba) under the trade name Irgacure 907 and alpha hydroxyl
ketones-Irgacure 184 and Irgacure 2959.
[0164] In an exemplary embodiment of the present invention, the
first building material also includes a sulfur-containing additive.
The sulfur containing additive is optionally selected from the
group consisting of beta mercaptopropionate, mercaptoacetate,
alkane thiols or any combination thereof. Some examples of beta
mercaptopropionate are: glycol di(3-mercaptopropionate),
pentaerythritol tetra(3-mercaptopropionate), and trimethylol
propane tri(3-mercaptopropionate).
[0165] The addition of sulfur-containing additive may significantly
enhances the composition reactivity, but many times this is
accompanied with reduced stability.
[0166] A composition according to an exemplary embodiment of the
invention comprises 40-60% mono-functional acrylic monomer, 15-30%
bi-functional urethane acrylic compound, 15-30% bi-functional
acrylic compound, 0.25-3% sulfur-containing component, 0.5%-3%
photo initiator, and the rest other curable components, surface
active agents, or other ingredients described herein according to
the intended properties of the composition.
[0167] In one embodiment of the present invention, the composition
suitable for building a three-dimensional object, further includes,
inter alia, a low molecular weight polymer. An example of a low
molecular weight polymer for the present embodiments is
Styrene-Butadiene-Methacrylate block copolymers (KRATON D),
manufactured by Dow Corning. Other suitable substances may be
used.
[0168] In one embodiment of the present invention the composition
suitable for building a three-dimensional object, further includes,
inter alia, a filler.
[0169] The term filler is defined as an inert material added to a
polymer, a polymer composition or other material to modify their
properties and/or to adjust quality of the end products. The filler
may be an inorganic particle, for example calcium carbonate, silica
and clay. Of course other filler substances may be used.
[0170] Fillers may be introduced in to polymer compositions in
order to reduce shrinkage during polymerization or during cooling,
for example to reduce the coefficient of thermal expansion,
increase strength, increase thermal stability reduce cost and/or
adopt rheological properties. The use of standard fillers has also
some drawbacks such as reduction of elasticity and an increase in
viscosity. Additionally, large diameter fillers (>5 micron) are
not appropriate for ink-jet applications.
[0171] Nano-particles fillers are especially useful in applications
requiring low viscosity such as ink-jet applications. Compositions
containing as much as 30% nano-particle fillers are feasible,
whereas the same concentration of more standard and higher diameter
fillers (.about.>1 micron) produce at such concentration
viscosities which are too high for ink-jet applications. In one
embodiment of the present invention, the nano-particle filler
containing composition is clear. The composition is clear (e.g.
transparent) since it contains no visual fillers. In contrast,
compositions containing more standard and higher diameter visible
fillers (.about.>1 micron), are not clear.
[0172] In one embodiment of the present invention, the composition
optionally may contain pigments. In a further embodiment of the
present invention, the composition optionally may contain dyes.
[0173] In another embodiment, the pigment concentration may be
lower than 35%. In another embodiment, the pigment concentration
may be lower than 15%. And also lower than 1%.
[0174] In one embodiment of the present invention, the filler may
include particles such as particles having an average diameter of
less than 100 nm. In another embodiment, the filler may include
particles having a diameter in the range of 10-100 nm. In another
embodiment, the filler may include particles having a diameter in
the range of 20-80 nm. In another embodiment, the filler may
include particles having a diameter in the range of 10-50 nm. In
another embodiment, the filler may include particles having a
diameter smaller than 10 nm. Examples of fillers that may be used
in the composition are HIGHLINK OG (particle size spanning between
9 nm to 50 nm), manufactured by Clariant, and NANOCRYL (particle
size below 50 nm), manufactured by Hanse Chemie. Other suitable
substances may be used In one embodiment of the present invention,
the first viscosity is about 80-500 cps. In another embodiment, the
first viscosity is about 300 cps. Of course, compositions having
other viscosities may be used.
[0175] In one embodiment of the present invention, the second
viscosity is lower than 20 cps and wherein the second temperature
is higher than 60.degree. C. In another embodiment, the second
viscosity is between 10 and 17 cps and wherein the second
temperature is higher than 60.degree. C. In another embodiment, the
second viscosity is between 10 and 17 cps and wherein the second
temperature is about 70-110.degree. C. In another embodiment, the
second viscosity is between 12 and 15 cps and wherein the second
temperature is about 70-90.degree. C. Of course, compositions
having other viscosities may be used.
[0176] Other components of the first interface material and the
second interface material of the present embodiments are
surface-active agents. A surface-active agent may be used to reduce
the surface tension of the formulation to the value required for
jetting or for printing process, which is typically around 30
dyne/cm. Examples of surface-active agents for the present
embodiments are silicone surface additives, marketed by Byk Chemie
under the trade names Byk.
[0177] Additional objects, advantages and novel features of the
present embodiments will become apparent to one ordinarily skilled
in the art upon examination of the following examples, which are
not intended to be limiting. Additionally, each of the various
embodiments and aspects of the present invention as delineated
hereinabove and as claimed in the claims section below finds
support in the following examples.
EXAMPLES
[0178] Reference is now made to the following examples, which
together with the above descriptions illustrate the exemplary
embodiments in a non-limiting fashion.
Example 1
Motivation
[0179] (a) Reduce on-site stock and storage by enabling the use of
a single modeling material to obtain different colors and/or
different properties. [0180] (b) Increase material shelf life:
[0181] (i) An additive, e.g., a curing agent, a hardening agent a
dye or pigment (color mix), might have a generally negative effect
on the shelf life of the modeling material. By enabling the user to
introduce the additive to the modeling material on site, per use
and shortly before use, will enable the user to benefit from the
full shelf life of the product. [0182] (ii) The additive being
required in relatively small amounts could be refrigerated or
otherwise stored under optimal conditions to further increase its
shelf life.
Materials
[0183] A cartridge containing modeling material.
[0184] A set of syringes containing different additives, e.g., dye
solutions or pigment dispersions or combinations between dyes and
pigments. The syringes may be external or internal to the
apparatus; and may be injected manually or automatically.
Method
[0185] (a) Inject color or color mix: The user may decide when to
inject or otherwise add the color mix to the cartridge, according
to the user's requirements. The user may stock a number of
different colors, and may also be able to use more than one color
combination to achieve additional desirable colors. [0186] (b)
Cartridge agitation: mixing of base modeling material and color mix
additive/s. [0187] (c) Allow bubbles to dissipate. [0188] (d) Load
cartridge to machine, as relevant. [0189] (e) Carry out material
resin replacement if necessary. [0190] (f) Material ready for
use.
Example 2
Motivation
[0190] [0191] (a) Dual curing: Specially designed formulations
containing dual curing components cannot be prepared by the resin
manufacturer due to a short pot life. Once the components have been
mixed, the pot life of some of such specially designed formulations
may, in some cases, last only a few days, after which time, the
product partially polymerizes, altering its properties to the
extent that it is no longer appropriate for its intended use.
[0192] (b) Example: hydroxyl reaction with isocyanate in addition
to radical polymerization of acrylic double bonds. Materials
[0193] A cartridge containing modeling material.
[0194] A syringe containing isocyanate component.
Method
[0195] (a) Inject isocyanate [0196] (b) Cartridge agitation: mixing
of base modeling materials and isocyanate. [0197] (c) Allow bubbles
to dissipate. [0198] (d) Load cartridge to machine [0199] (e) Carry
out material resin replacement if necessary [0200] (f) Build
desired parts [0201] (g) Flush out system in order to remove
reactive formulation from system, e.g., by carrying out resin
replacement [0202] (h) Postcure parts at high temperature, if
necessary.
Example 3
Motivation
[0203] Thiolene reaction: This reaction, while having many
advantages, suffers from very short formulation shelf life.
Materials
[0204] A cartridge containing a metha/acryl modeling material.
[0205] A syringe containing mercaptopropionate component.
Method
[0206] (a) Inject mercaptopropionate. [0207] (b) Cartridge
agitation: mixing of base modeling materials and
mercaptopropionate. [0208] (c) Allow bubbles to dissipate. [0209]
(d) Load cartridge to machine [0210] (e) Carry out material resin
replacement if necessary [0211] (f) Material ready for
building.
[0212] Other chemicals can also be mixed using this technique. For
example, a formulation can be stable until the addition of a
catalyst, a cross linker, etc.
[0213] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
subcombination.
[0214] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims. All
publications, patents and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention.
* * * * *