U.S. patent application number 17/012180 was filed with the patent office on 2021-01-28 for co-extrusion of periodically modulated structures.
The applicant listed for this patent is PALO ALTO RESEARCH CENTER INCORPORATED. Invention is credited to SCOTT E. SOLBERG.
Application Number | 20210023758 17/012180 |
Document ID | / |
Family ID | 1000005092177 |
Filed Date | 2021-01-28 |
United States Patent
Application |
20210023758 |
Kind Code |
A1 |
SOLBERG; SCOTT E. |
January 28, 2021 |
CO-EXTRUSION OF PERIODICALLY MODULATED STRUCTURES
Abstract
A method of forming an extruded structure includes dispensing at
least a first material through an extrusion head, varying a
pressure applied during extrusion of the first material over time,
and depositing the first material on a substrate, wherein a width
of the first material varies with a pressure forming a stripe of
the first material having a varying width along a length of the
stripe.
Inventors: |
SOLBERG; SCOTT E.; (SAN
JOSE, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PALO ALTO RESEARCH CENTER INCORPORATED |
Palo Alto |
CA |
US |
|
|
Family ID: |
1000005092177 |
Appl. No.: |
17/012180 |
Filed: |
September 4, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14010076 |
Aug 26, 2013 |
10800086 |
|
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17012180 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 48/19 20190201;
B29C 48/20 20190201; B29C 48/13 20190201; B29C 48/07 20190201; Y10T
428/2976 20150115; Y10T 428/249921 20150401 |
International
Class: |
B29C 48/13 20060101
B29C048/13 |
Claims
1. A method of forming an extruded structure, comprising:
dispensing at least a first material through an extrusion head;
varying a pressure applied during extrusion of the first material
over time; and depositing the first material on a substrate,
wherein a width of the first material varies with a pressure
forming a stripe of the first material having a varying width along
a length of the stripe.
2. The method of claim 1, wherein varying a pressure comprises
modulating a spool valve motor over time.
3. The method of claim 1, wherein varying a pressure comprises
modulating a piston drive over time.
4. The method of claim 3, wherein modulating a piston drive
comprises modulating a rotary motor over time.
5. The method of claim 4, wherein modulating the rotary motor over
time comprises modulating a cam attached to the rotary motor over
time.
6. The method of claim 3, wherein modulating a piston drive
comprises modulating a linear, moving coil actuator.
7. The method of claim 1, wherein dispensing at least a first
material through an extrusion head comprises dispensing a first
material and a second material.
8. The method of claim 7, wherein dispensing the first and the
second material comprises: modulating pressure over time for the
first material in a first pattern; and modulating pressure over
time for the second material in a second pattern, wherein the
second pattern is complementary to the first pattern.
9. The method of claim 8, further comprising removing the second
material.
10. The method of claim 9, further comprising filling a space left
by removal of the second material with another material.
11. The method of claim 9, wherein the first pattern has wider and
narrower portions and the second pattern has narrower portions that
match the wider portions in the first pattern and the second
pattern has wider portions that match the narrower portions of the
first pattern.
12. The method of claim 1, wherein dispensing at least a first
material through an extrusion head comprises dispensing the first
material, a second material and a third material.
13. The method of claim 1, further comprising performing the
dispensing, varying and depositing with the extrusion head at a
first position and repeating the dispensing, varying and depositing
with the extrusion head at a second position.
14. The method of claim 13, wherein the second position is adjacent
the first position one of either horizontally or vertically.
15. The method of claim 12, wherein the first and third materials
have patterns that are in phase, and the second material has a
pattern that is complementary to the patterns of the first and
third material.
16. The method of claim 1, wherein the varying width has a periodic
pattern along the length.
17. The method of claim 1, wherein the periodic pattern is a
sinusoidal pattern.
18. The method of claim 1, wherein the varying width has a
randomized pattern along the length.
19. The method of claim 1, wherein the first material is
electrochemically active.
20. The method of claim 19, wherein the first material forms at
least a portion of a battery electrode.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/010,076 filed Aug. 26, 2013, which is incorporated
herein by reference in its entirety.
BACKGROUND
[0002] It is possible to extrude pastes and other viscous materials
through an extrusion head to deposit the material onto a surface.
The process may sometimes be referred to as micro-extrusion to
differentiate it from extrusion processes using dies on large
machines. The materials exiting the extrusion head are generally
referred to as extrudates. The extrusion head typically has at
least one input port to receive the material from some sort of
reservoir, and at least one output port or die or nozzle to allow
the extrudate to exit the head. A pump connected to the reservoir
of material controls the flow, which in turn affects the resulting
stripe of extrudate.
[0003] For most applications, it is desirable that the extrudate
stripes have uniform shape and density. Extruded terminology
generally refers to a single stripe of material as a
one-dimensional structure. Structures having two or more stripes of
material are referred to as two-dimensional. It is possible to form
limited three-dimensional structures using extrusion heads in
multiple passes, but the manufacturability issues and costs make
that approach difficult. Hollow cavities, overhangs and other
`hidden` features require additional extrusion passes and/or
additional processing steps. Generally, two dimensional extruded
structures have multiple, linear, stripes of extrudates.
[0004] Being able to create features that are more than
two-dimensional and not necessarily straight line features with an
extrusion head would have advantages in surface area and material
utilization for some applications. It is possible to vary the flow
of material over time to generate extruded structures that are not
linear, uniform stripes of extrudates.
SUMMARY
[0005] According to aspects of the present disclosure, there is
provided a method of forming an extruded structure that includes
dispensing at least a first material through an extrusion head,
varying a pressure applied during extrusion of the first material
over time, and depositing the first material on a substrate,
wherein a width of the first material varies with a pressure
forming a stripe of the first material having a varying width along
a length of the stripe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows a prior art two dimensional structure.
[0007] FIG. 2 shows a prior art two dimensional structure after
removal of a sacrificial material.
[0008] FIG. 3 shows a three dimensional structure formed in a
method according to the prior art.
[0009] FIG. 4 shows an embodiment of a near-three dimensional
structure of material having varying widths.
[0010] FIG. 5 shows an embodiment of a near-three dimensional
structure of two materials having complementary patterns of varying
widths.
[0011] FIG. 6 shows an embodiment of a near-three dimensional
structure of three materials.
[0012] FIG. 7 shows an embodiment of a system for modulating
pressures in an extrusion head.
[0013] FIG. 8 shows a graph of paste pressures in an extrusion
head.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0014] FIG. 1 shows a two-dimensional structure in accordance with
the prior art. It is two-dimensional in that it has at least two
stripes of materials. In extrusion, the simplest structures
resulting from one circular or rectangular slot in an extrusion
head is generally considered to be one-dimensional (1D). The next
level of complexity would encompass 2D structures, resulting from
extrusion heads that have multiple slots, such as 10 shown in FIG.
1. The same material 14 may be simultaneously extruded from
different slots of the same or different forms, or multiple
materials such as 12 and 14 could be co-extruded from multiple
slots. In some structures, the second material 12 may be sacrificed
to form gaps in the structure, where after removal the second
material of the structure would then become air, as shown in FIG.
2.
[0015] A further level of complexity would be to achieve 3D
structures such as 20, typically with multiple passes of the
extrusion head to form layers of extruded materials such as 24 and
26. True 3D structures could include hidden features such as voids,
overhangs, re-entrant features, etc., typically not achievable
using a single pass of an extrusion head. However, it is possible
to achieve `near-3D` structures, having higher complexity than
simple stripes or runs of multiple materials from a single pass
extrusion head.
[0016] The embodiments here may be referred to as `near-3D` or 2.5D
structures. The features of the resulting stripes of materials are
more complex than simple stripes of materials, having varying
widths along their lengths. This may be accomplished by varying the
pressure used to extrude the materials over time. FIG. 4 shows an
embodiment or a representation of such a `near-3D` structure 30.
The extrudate stripes 34 have varying width along their length,
referred to here as periodically modulated stripes. The stripes may
be extruded from a single material 34 from an extrusion head. The
varying width may have a periodic pattern as shown, but the varying
width may also have a non-periodic, or randomized, pattern.
However, the use of a periodic pattern of the first extrudate
allows for some variations.
[0017] FIG. 5 shows a near-3D structure having extrudate stripes of
periodically varying widths. The first extrudate 34 has a first
pattern of varying widths. The second extrudate 36 has a
complementary second pattern where the wide portions and narrow
portions of the second pattern match up to the narrow portions and
wide portions of the first pattern. The two patterns are
accomplished by periodically modulating the pump differently over
time for each pattern. The modulation of the flow of materials over
time allows the formation of the patterns.
[0018] The two materials may consist of any material that can be
extruded through the extrusion head. Typically, the materials are
pastes. The materials remain separate from each other. The
materials may be a mixture of other materials, but for the purposes
of this discussion, when they exit the print head as extrudates
they are each one material. Similarly, the two extrudates remain
separate from each other, even though they may be extruded
together. Some mixing may occur at the material boundaries, but the
integrity of each is substantially maintained. One should note that
the examples here discuss two materials, but more than two
materials may be used.
[0019] FIG. 6 shows an example of a near-three dimensional
structure having more than two materials. The extrudates 34 and 36
have another extrudate 38 in the structure. The materials are
modulated with respect to time as before, but the extrudates 34 and
38 would be modulated in phase with each other to form the patterns
that complement the pattern of extrudate 36. For example, the
extrudates may form the pattern of extrudate 34, extrudate 36,
extrudate 38, extrudate 36, extrudate 34, etc.
[0020] The pastes may contain materials which would form
electrically conductive or electrochemically active structures, as
examples. Electrochemically active materials may be used in
electrode structures that make up part of batteries. Non-active
materials may be used as filler and then sacrificed. If non-active,
or sacrificial, material is used, then once the non-active material
is removed, such as be drying, sintering, etc., it can be replaced
with another material; but in the instance where no other material
is subsequently introduced, then gaps would remain, where the
second material would be air.
[0021] If for example one of the materials is electrochemically
active, a simple model assuming sinusoidal modulation has shown
that the resulting structure has approximately 21% greater
periphery while having about 10% less average distance between the
centerline of an extruded stripe and the nearest border, compared
to a conventional linear extruded structure. This increase in
surface area, and decrease in the average distance between the
interior and border, could for example enhance functional material
reaction rates or utilization. Even such a small improvement could
be economically significant in a cost-sensitive business such as
battery manufacturing.
[0022] To vary the widths along the length of the features, the
dispensing system uses a pump to create a pressure that then forces
the paste out of the extrusion head. One embodiment uses a spool
valve to modulate the flow from the pump. Spool valves typically
consist of a cylinder housed in a case. The case contains a system
of valves that connect to a reservoir and pump on one side. The
spools in the valve slide or rotate in the system in response to
fluid flow levels to either open or block channels. The fluid from
the reservoir flows through the open channels. Typically, spool
valves have a controller device that actuates the valve to rotate
the spools into the necessary position. FIG. 6 shows an example of
this type of system.
[0023] In FIG. 7, the motor/pump 40 would connect to the reservoir
of material or reservoirs of materials. The controller 46 may
control the pump/motor and/or the valve 42. The fluid then flows
out of the extrusion head 44 in response to the pressure. In one
embodiment, a pressure modulation cycle of 18 milliseconds (msec)
is used.
[0024] FIG. 8 shows graphical representations of downstream paste
pressure responses for rapid partial strokes. Paste #1 is a
functional paste in this embodiment, and #2 is a sacrificial paste.
Curve 50 is the pressure of paste #1, and curve 52 is for paste
#2.
[0025] Another embodiment may employ a rotary motor to drive a cam,
which in turn would drive a piston. Another piston embodiment may
use a linear, moving-coil actuator that would require a mechanical
linkage to produce enough force to push on the high pressure
paste.
[0026] Other variations and modifications exist. The embodiments up
to this point have assumed that the materials reside adjacent to
each other laterally. It is also possible that the materials can be
stacked vertically. Further, the vertical thickness of the
materials may be of any thickness. Typically, the thickness may be
approximately 10 microns or greater.
[0027] It will be appreciated that several of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also that various presently unforeseen or
unanticipated alternatives, modifications, variations, or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
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