U.S. patent application number 14/755392 was filed with the patent office on 2015-10-22 for system and method for extruding parts having microstructures.
This patent application is currently assigned to HOOWAKI, LLC. The applicant listed for this patent is Hoowaki, LLC. Invention is credited to Andrew H. Cannon, Ralph A. Hulseman, William P. King, March Maguire.
Application Number | 20150298379 14/755392 |
Document ID | / |
Family ID | 46721475 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150298379 |
Kind Code |
A1 |
Hulseman; Ralph A. ; et
al. |
October 22, 2015 |
System and Method For Extruding Parts Having Microstructures
Abstract
A manufacturing apparatus for manufacturing extruded parts
having microstructures comprising: a support structure; a hopper
carried by the support structure for receiving feedstock; an
extrusion chamber operatively associated with the hopper for
receiving the feedstock from the hopper and melting the feedstock
above a feedstock melting temperature; a die carried by the support
structure having die microstructures disposed on an inner surface
of the die, the die microstructures having a plurality of
microfeatures each having an upper surface and a lower surface, the
melted feedstock being forced through the die to produce an
extrudate having extrudate microstructures; and, a cooling assembly
wherein the extrudate microstructures of the pre-cooled extrudate
have larger physical dimensions than that of the extrudate
microstructures of the cooled extrudate.
Inventors: |
Hulseman; Ralph A.;
(Greenville, SC) ; Cannon; Andrew H.; (Columbia,
SC) ; King; William P.; (Champaign, IL) ;
Maguire; March; (Clemson, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hoowaki, LLC |
Pendleton |
SC |
US |
|
|
Assignee: |
HOOWAKI, LLC
Pendleton
SC
|
Family ID: |
46721475 |
Appl. No.: |
14/755392 |
Filed: |
June 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13404707 |
Feb 24, 2012 |
9120670 |
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14755392 |
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61446180 |
Feb 24, 2011 |
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Current U.S.
Class: |
428/141 |
Current CPC
Class: |
B29K 2101/12 20130101;
B29C 55/22 20130101; B29L 2031/756 20130101; B29C 48/06 20190201;
B29C 48/10 20190201; B29K 2995/0074 20130101; B29C 48/919 20190201;
B29C 48/12 20190201; B29K 2995/0093 20130101; B29C 48/90 20190201;
B81C 99/0015 20130101; B29C 48/09 20190201; B29C 48/08
20190201 |
International
Class: |
B29C 47/00 20060101
B29C047/00; B29C 47/12 20060101 B29C047/12 |
Claims
1. An extruded part having microstructures comprising: an
extrudate; the extrudate having pre-cooled extrudate
microstructures when the extrudate is in a pre-cooled state, the
extrudate having post-cooled extrudate microstructures when the
extrudate is in a post-cooled state wherein the post-cooled
extrudate microstructures have a height in the range of 70 to 90
.mu.m, a width in the range of 120 to 160 .mu.m, and a general
slope shape, and, wherein the pre-cooled extrudate microstructures
have larger physical dimensions than that of the post-cooled
extrudate microstructures.
2. The extruded part of claim 1 wherein the post-cooled extrudate
has a physical shape taken from the group consisting of a film, a
square column, rectangular column, trapezoidal column, asymmetrical
column, circular column, oval column, triangular column and any
combination of these.
3. The extrude part of claim 1 wherein the extrudate includes: the
extrudate having pre-gathered extrudate microstructures when the
extrudate is in a pre-gathered state; the extrudate having gathered
extrudate microstructures state wherein the extrudate is in a
gathered state; and, wherein the pre-gathered extrudate
microstructures have larger physical dimensions than that of the
gathered extrudate microstructures.
4. The extrude part of claim 1 wherein the post-cooled extrudate
microstructures include physical characteristics selected from the
group consisting of: hydrophobicity, hydrophilicity, self-cleaning,
decreased or increased hydro-dynamic drag coefficients, decreased
or increased aerodynamic drag coefficients, increased friction,
reduced friction, optical effects, increased adhesion, decreased
adhesion, oleophobicity, oleophillicity, tactile effects,
anti-blocking and any combination of these.
5. The extruded part of claim 1 wherein the extrudate has post
extrusions assemble extrudate microstructures after the extrudate
is passed through a post extrusion assembly.
6. The extruded part of claim 5 wherein the post-cooled extrudate
microstructures have larger physical dimensions than that of post
extrusions assemble extrudate microstructures.
7. The extruded part of claim 6 where the extrudate is altered by
the post extrudate assembly in a manner taken from the group
consisting of: drawing down, flattening, stretching, embossing,
coating, stamping, rolling, spiraling, heating, freezing and any
combination of these
8. The extruded part of claim 1 where the post-cooled extrudate
microstructures are disposed on the exterior walls of the
extrudate.
9. The extruded part of claim 7 including an interior cavity
defined in the extrudate.
10. The extruded part of claim 8 including microstructures disposed
on an inner surface of the interior cavity.
11. An extruded part having microstructures comprising: an
extrudate; the extrudate having pre-cooled extrudate
microstructures when the extrudate is in a pre-cooled state; the
extrudate having post-cooled microstructures when in a post-cooled
state, wherein the post-cooled extrudate microstructures have
dimensions in the range of 0.1 and 500 .mu.m; and, wherein the
pre-cooled extrudate microstructures have a larger physical
dimensions than that of the post-cooled extrudate
microstructures.
12. The extruded part of claim 11 wherein the post-cooled extrudate
microstructures are selected from the group consisting of: pillers,
voids, steps, ridges, curved regions, recessed regions, columns,
cross-section shapes comprising circles, ellipses, triangles,
squares, rectangles, polygons, stars, hexagons, letters, numbers,
symbols, and any combination of these.
13. The extruded part of claim 11 including a channel defined by
the post-cooled extrudate microfeatures.
14. The extruded part of claim 13 wherein the channel defined by
the post-cooled extrudate microfeatures has a depth between 300
.mu.m and 400 .mu.m.
15. The extruded part of claim 13 wherein the channel defined by
the post-cooled extrudate microfeatures has a width between 100
.mu.m and 160 .mu.m.
16. The extruded part of claim 11 wherein area of the post-cooled
extrudate microstructures is 0.5 to 25 times smaller when compared
to an area of the pre-cooled extrudate microfeatures.
17. The extruded part of claim 11 wherein the post-cooled extrudate
microfeatures includes a first region of microfeatures having
physical dimensions between 10 nm and 1 .mu.m and a second region
of microfeatures having physical dimensions between 1 .mu.m and 100
.mu.m.
18. An extruded part having microstructures comprising: an
extrudate; the extrudate having pre-cooled extrudate
microstructures when the extrudate is in a pre-cooled state, the
extrudate having post-cooled extrudate microstructures when the
extrudate is in a post-cooled state; and, wherein the ratio of the
size of the pre-cooled extrudate microstructures to the post-cooled
extrudate microstructures is in the range of 1:1 to 7:1.
19. The extruded part of claim 18 wherein the post-cooled extrudate
microstructures have a width in the range of 7 .mu.m to 10
.mu.m.
20. The extruded part of claim 18 wherein the post-cooled extrudate
microstructures defined a channel having a width in the range of
0.25 mm to 1.25 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1) Field of the Invention
[0002] This invention is directed to a system and method of making
parts and more specifically, a system and method of making parts
using the manufacturing process of extrusion wherein the resulting
parts have microstructures imparted on their surface.
[0003] 2) Description of the Related Art
[0004] Extrusion is a manufacturing process that is used to create
parts having a fixed cross-sectional profile. Extrusion material is
pushed or drawn through an extrusion or drawings die of a desired
cross-section. Extrusion can be used with extrusion material that
is brittle since the extrusion material only encounters compressive
and shear stresses. Extrusion also can produce finished parts with
surface finish.
[0005] Extrusion may be a continuous process which can
theoretically produce indefinitely long parts. In one form,
extrusion produces semi-continuous parts resulting in a replication
of virtually identical parts or parts having the same
cross-section, but varying lengths. The extrusion process can be
done with extrusion material that is hot or cold. Commonly extruded
materials include metals, polymers, plastics, ceramics, concrete
and foodstuffs.
[0006] Solid parts can be produced with a simply flat extrusion
die. Hollow cavities within parts can be produced with a die having
depth, beginning first with a shape profile that supports the
center section. The die shape then internally changes along its
length into the final shape, with the suspended center pieces
supported from the back of the die. Mandrels can also be used to
produce extruded parts having cavities.
[0007] Parts can also be effected by the drawings process. Drawing
is a manufacturing process which uses tensile forces to stretch
material. Generally, drawings is described as sheet drawing or
wire, bar, and tube drawing. Sheet drawing involves deformation
over a curved axis. Wire, bar, and tube drawing pulls material
through a drawings die to reduce its diameter and increase its
length. Drawing is usually done at room temperature, thus
classified a cold working process, however it may be performed at
elevated temperatures to hot work large wires, rods or hollow
sections in order to reduce forces. Drawings can be used for metals
and non-metals.
[0008] Under the current state of the art, the extrusion process
(which includes drawing), generally produces a surface with a
smooth or fine finish. It would be advantageous to be able to
impart surface properties onto extrusion material during the
extrusion process which results in the parts resulting from the
extrusion process having certain physical properties.
[0009] Microfeatures placed on a part can provide for advantageous
surface properties. By including a plurality of microfeatures on
the surface of an object, other characteristics may be imparted to
the object, such as increased hydrophobicity, hydrophilicity,
self-cleaning ability, hydro-dynamics drag coefficients,
aerodynamic drag coefficients, frictional properties, and optical
effects. Superhydrophobic surfaces were first inspired by the
characteristic water repellency of the lotus leaf.
[0010] Historically, microfeatures were applied to surfaces as
coating, adhesive or chemical reaction and therefore are prone to
wear off the surface. Over time the properties provided by the
microstructures are lost. Further, the applications of a coating or
adhesive would have to be added to the extrusion process and would
not naturally be integrated into the extrusion process.
[0011] The information contained in PCT Patent Application:
US09/43306, "Method of Manufacturing Microstructures", filed on May
8, 2009; PCT Patent Application: US09/43307, "Flexible
Microstructured Superhydrophobic Materials", filed on May 8, 2009
and PCT Patent Application: US09/49565, "Casting Microstructures
into Stiff and Durable Materials from a Flexible and Reusable
Mold", filed on Jul. 2, 2009 are incorporated by reference.
[0012] Therefore, it is an object of this invention to provide a
manufacturing method for manufacturing parts using the extrusion
process that resulted in parts having microfeatures.
[0013] It is another object of this invention to provide an
extrusion die which results in parts having microfeatures imparting
certain physical properties to the manufactured part even when
drawing.
[0014] It is another object of this invention to provide an
extrusion die that has microfeatures on its surface, such that
these microfeatures are imparted on a resulting part thereby
affecting the performance or properties of the extruded part.
SUMMARY OF THE INVENTION
[0015] The objects above are achieved by providing a manufacturing
apparatus, and a method, for manufacturing extruded parts having
microstructures comprising: a support structure; a hopper carried
by said support structure for receiving feedstock; an extrusion
chamber operatively associated with said hopper for receiving said
feedstock from said hopper and melting said feedstock above a
feedstock melting temperature; a die carried by said support
structure having die microstructures disposed on an inner surface
of said die, said die microstructures having a plurality of
microfeatures each having an upper surface and a lower surface,
said lower surface having an arc defined in said lower surface,
said melted feedstock being forced through said die to produce a[n]
pre-cooled extrudate having pre-cooled extrudate microstructures;
an upper channel defined in said upper surface including a concave
portion; and, a cooling assembly wherein said extrudate
microstructures of said pre-cooled extrudate have larger physical
dimensions than that of said post-cooled extrudate microstructures
of said a post-cooled extrudate wherein said post-cooled extrudate
microstructures has a height in the range of 70 to 90 .mu.m, a
width in the range of 120 to 160 .mu.m and a general slope
shape.
[0016] The invention can result in extrudate having a physical
shape taken from the group consisting of a film, a square column,
rectangular column, trapezoidal column, asymmetrical column,
circular column, oval column, triangular column and any combination
of these. A take up roller can be included for gathering said
post-cooled extrudate wherein said extrudate microstructures of
said pre-gathered extrudate have larger physical dimensions than
that of said extrudate microstructures of said gathered extrudate.
A post extrusion assembly can be included for physically altering
said extrudate in a manner taken from the group consisting of:
drawing down, flattening, stretching, embossing, coating, stamping,
rolling, spiraling, heating, freezing and any combination of these;
and, wherein said extrudate microstructures of said extrudate have
larger physical dimensions than that of said extrudate
microstructures of said extrudate after said extrudate passes
through said post extrusion assembly.
[0017] The invention can include a die having a planar surface;
and, an arc included in said lower surface of at least one
microfeature disposed on said planar surface. Also a first wall can
be included in at least one microfeature disposed on said planar
surface having an angle of incident less than 90.degree. in
relation to said upper surface. The resulting extrudate
microstructures can have a height in the range of 150 to 250 .mu.m,
a width in the range of 150 to 250 .mu.m and a general pillar
shape. A microfeature planar surface can be included in said
microfeature disposed along said lower surface with a second arc
included in said microfeature disposed adjacent to said
microfeature planar surface; and, a second wall included in
microfeature having an angle of incident greater than 90.degree. in
relation to said upper surface. An upper arc can be included in
said upper surface and a channel can be defined by said
microfeature having a width between 100 and 160 .mu.m and a depth
between 300 and 400 .mu.m.
[0018] The invention can include a curved surface in said die
having microfeatures; a channel defined in at least one
microfeature included in said curved surface; and, an arc defined
in said lower surface of said microfeature included in said curved
surface. A second arc can be defined in said lower surface and can
be disposed adjacent to said arc. A first wall can be included in
said microfeature having an angle of incident less than 90.degree.
in relation to said upper surface and a second wall can be included
in said microfeature having an angle of incident greater less than
90.degree. in relation to said upper surface.
[0019] A mandrel can be carried by said support structure having
microstructures deposed on an outer surface so that said extrudate
will include an interior cavity having microstructures on an inner
surface of said interior cavity.
[0020] The extrudate microstructures can include physical
characteristics selected from the group consisting of:
hydrophobicity, hydrophilicity, self-cleaning, decreased or
increased hydro-dynamic drag coefficients, decreased or increased
aerodynamic drag coefficients, increased friction, reduced
friction, optical effects, increased adhesion, decreased adhesion,
oleophobicity, oleophillicity, tactile effects, anti-blocking and
any combination of these. The extrudate microstructures can be
selected from the group consisting of: pillers, voids, steps,
ridges, curved regions, recessed regions, columns, cross-section
shapes comprising circles, ellipses, triangles, squares,
rectangles, poly ions, stars, hexagons, letters, numbers, symbols,
and any combination of these. An overhang structure can be included
in said die microstructures.
[0021] The invention also includes a method of manufacturing an
extruded item by an extrusion manufacturing process comprising the
steps of: providing an extrusion feedstock; providing an extrusion
die having microstructures disposed on an interior surface of said
die, said die having a plurality of microfeatures having a depth
about between 0.1 and 500 .mu.m wherein each of said microfeatures
includes an upper surface and a lower surface; and, creating an
extrudate having extrudate microfeatures by forcing said feedstock
through said extrusion die so that said extrudate includes physical
properties selected from the group consisting of: hydrophobicity,
hydrophilicity, self-cleaning, decreased or increased hydro-dynamic
drag coefficients, decreased or increased aerodynamic drag
coefficients, increased friction, reduced friction, optical
effects, increased adhesion, decreased adhesion, oleophobicity,
oleophillicity, tactile effects, anti-blocking and any combination
of these.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The description of the invention will be explained with
reference to the following figures:
[0023] FIGS. 1A through 1D are perspective views of aspects of the
invention;
[0024] FIG. 2 is a perspective view of aspects of the
invention;
[0025] FIG. 3A through 3C are side views of aspects of the
invention;
[0026] FIG. 4A is a perspective view of aspects of the
invention;
[0027] FIG. 4B is a portion of an extrudate resulting from the
invention;
[0028] FIG. 5A through 5D are cross sections of portions of
extrudate resulting from the invention;
[0029] FIG. 6 is a schematic of aspects of the invention;
[0030] FIGS. 7 through 11 are elevation views of a portion of
aspects of the invention;
[0031] FIG. 12 is a schematic of aspects of the invention;
[0032] FIG. 13 is an elevation view of a portion of aspects of the
invention;
[0033] FIG. 14 is a cross section of extrudate resulting from the
invention;
[0034] FIG. 15A is a perspective of aspects of the invention;
[0035] FIG. 15B is a cross section of aspects of the invention;
[0036] FIG. 16A is a cross section of aspects of the invention;
[0037] FIG. 16B is a elevation of a portion of the aspects of the
invention;
[0038] FIG. 17 is a cross section of aspects of the invention;
[0039] FIGS. 18 through 20 are cross sections and enlargements of
portions of the cross sections of aspects of the invention;
[0040] FIG. 21A is a side view of an aspect of the invention with
an enlargement of a portion of the side view;
[0041] FIG. 21B is a cross section of aspects of the invention;
[0042] FIG. 22A is a perspective view of the prior art;
[0043] FIG. 22B is a perspective view of the resulting extrudate of
the invention;
[0044] FIG. 22C is a front view of an aspect of the invention;
[0045] FIG. 22D is a perspective view of aspects of the invention;
and,
[0046] FIG. 22E is a top view of aspects of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] In general the terms and phrases used herein have their
art-recognized meaning, which can be found by reference to standard
texts, journal references and contexts known to those skilled in
the art. Referring to FIG. 1, extrusion material (also called feed
stock, a blank or a billet) 16 is pressed through die 10 resulting
in an extruded part 18. The die can be made by a number of
manufacturing processes including molding, forming and electric
discharging machining.
[0048] Microstructures can be imparted to the surface of metal dies
with subtractive methods such as direct machining, cutting, or
scoring, or laser machining; additive methods such as spraying,
coating, or inserts incorporated onto the die surface; and surface
alteration methods that neither add nor subtract such as micro
molding the metal die surface.
[0049] Microstructures can be imparted to the surface of polymer
dies with subtractive methods such as direct machining, cutting, or
scoring, or laser machining; additive methods such as spraying,
coating, or inserts incorporated onto the die surface; and surface
alteration methods that neither add nor subtract such as micro
molding the metal die surface. Polymer dies can also be molded, and
microstructures can be imparted via the mold. A common polymer die
material is ultem. The microstructured molded polymer die can be
machined after molding.
[0050] Microstructures can be imparted to the surface of ceramic
dies with subtractive methods such as direct machining, cutting,
scoring, or laser machining; additive methods such as spraying,
coating, or inserts incorporated onto the die surface. Ceramic dies
can also be molded, and microstructures can be imparted via the
mold. The microstructured molded ceramic die can be machined after
micromolding.
[0051] Extrusion dies can be manufactured or have microstructures
applied to them as indicated in the PCT application referenced
above. Dies can include a single outlet opening or multiple outlet
openings. Further, the die can be a single part or an assembly of
parts. The die material can be metal, polymer or ceramic. Common
die materials include steel, aluminum, and titanium.
[0052] Included in the die is an outlet die member 11 having an
outlet contact surface 13 forming an outer surface of the resulting
part. In one embodiment, the diameter of the blank is reduced
though the extrusion process. As shown, die 10 contacts the blank
on an outer surface 19 of the resulting part 18. In the event that
the resulting part needs to include a cavity, a mandrel 12 can be
included in the die which forms the cavity within the blank.
Mandrel 12 can include a mandrel contact surface 13 which forms an
inner surface of the resulting part. Dies capable of forming
extruded parts having cavities include spider dies, porthole dies
or bridge dies.
[0053] Extrusion material can be metal or non-metal and can include
rubber (including natural rubber, styrene-butadiene, polybutadiene,
neoprene, ethylene-propylene, butyl, nitrile, silicones), acrylic,
nylon, polycarbonate, polyester, polyethylene, polypropylene,
polystyrene, polyvinyl chloride, polyolefin and other flexible
polymers known to those of skill in the art.
[0054] Microstructures are included on the outlet contact surface.
Microfeatures can include holes, pillars, steps, ridges, curved
regions, recessed regions, raised regions, and any combination of
these employing any cross-sectional shape including circles,
ellipses, triangles, squares, rectangles, polygons, stars,
hexagons, letters, numbers, mathematical symbols and any
combination of these.
[0055] When the extrusion material comes in contact with
microstructures on the die, microstructures are imparted on the
surface of the resulting part. These microstructures can increase
hydrophobicity to the part, decrease hydrophobicity to the part
and/or give the part a self-cleaning ability. The microfeatures can
also impart optical effects, for example giving an object a
prismatic effect, a specific color, or a directional dependent
color change or color flop (e.g. the object appears a specific
color when viewed from one angle and another color when viewed from
another direction).
[0056] The microfeatures can also impart a surface friction or grip
to the part, or can give an object a specific tactile sensation
such as feeling fuzzy, rough or squishy when touched. In a specific
embodiment, the microfeatures can modify the heat transfer
characteristics of an object, for example by changing the surface
area of an object, changing how the surface interacts with fluids,
or changing the behavior of nucleation sites. In a specific
embodiment, the microfeatures can result in a decreased heat
transfer by conduction, for example when the microfeatures have a
high aspect ratio only the tops of the microfeatures will be in
contact with another object for conductive heat transfer while the
voids between surface features will not transfer heat well.
Further, the surface of the resulting part can include
microstructures that include "drainage" abilities allowing fluids
to drain from the part surface. Further, the microstructures can
provide for a capillary action allowing fluid to flow against
gravity. Friction can also be modified by particular
microstructures imparted to the surface of the results part.
[0057] Microstructures can also be electrically conductive, for
example metal microstructures or microstructures comprised of an
electrically conductive polymers. These types of electrically
conductive microstructures are useful, for example, as an array of
electrical leads for electronic devices. The electrically
conductive microstructures, for example, can be embossed directly
onto the surface of an object. In some circumstances, the
microstructures on the surface of the extrudate can mirror the
microstructures on the die or mandrel. In other circumstances, the
microstructures on the extrudate can be of a different size or
shape. Extrudate drawing, stretching, or other manipulations can
change the shape of the microstructures, for example, shrinking the
microstructures down in size by an order of magnitude or more.
[0058] In a specific embodiment, the microfeatures have dimensions
selected over the range of 10 nm to 1000 .mu.m. In an embodiment,
for example, the microfeatures have a length, height, diameter,
and/or width selected over the range of 10 nm to 1000 .mu.m,
preferably for some embodiments selected over the range of 10 nm to
100 .mu.m. In an embodiment, for example, a pitch between
microfeatures is selected over the range of 10 nm to 1000 .mu.m,
for some applications selected over the range of 1 .mu.m to 1000
.mu.m, and for some applications selected over the range of 10
.mu.m to 1000 .mu.m.
[0059] In one embodiment, a preselected pattern of microfeatures
includes a region of microfeatures having a first cross sectional
shape and a region of microfeatures having a second cross sectional
shape, for example different from the first cross sectional shape.
In one embodiment, a preselected pattern of microfeatures includes
a region of microfeatures having multiple cross sectional shapes
and/or sizes. In an embodiment, a preselected pattern of
microfeatures refers to two or more arrays of microfeatures of two
or more cross-sectional shapes and/or sizes. In a specific
embodiment, the two or more arrays are positioned side by side;
that is, where the two arrays do not overlap. In another specific
embodiment, the two or more arrays are positioned to overlap, and
microfeatures having the two or more cross sectional shapes and/or
sizes are interspersed within the overlapping arrays.
[0060] In an embodiment, a preselected pattern of microfeatures
includes multiple dimensions of microfeatures, for example a
bimodal or multimodal distribution of dimensions. The size
distribution could also be random, or the size could correspond to
the location of the microfeature on the mandrel or die. In an
exemplary embodiment, a preselected pattern of microfeatures
includes a first group of microfeatures having dimensions selected
from 10 nm to 1 .mu.m and a second group of microfeatures having
dimensions selected from 1 .mu.m to 100 .mu.m. In a specific
embodiment, the sizes, shapes and positions of the microfeatures
are preselected with micrometer-scale or nanometer-scale accuracy
and/or precision.
[0061] In an embodiment, the microstructured surface comprises a
polymer. Useful polymers include, but are not limited to: PDMS,
PMMA, PTFE, FEP, PEEK, polyurethanes, Teflon, polyacrylates,
polyarylates, thermoplastics, thermoplastic elastomers,
fluoropolymers, biodegradable polymers, polycarbonates,
polyethylenes, polyimides, polystyrenes, polyvinyls, polyolefins,
silicones, natural rubbers, synthetic rubbers and any combination
of these.
[0062] In an embodiment, the microstructured surface comprises a
metal. Useful metals include any moldable, castable, embossable
and/or stampable metal or alloy. Useful metals include, but are not
limited to: aluminum, aluminum alloys, bismuth, bismuth alloys,
tin, tin alloys, lead, lead alloys, titanium, titanium alloys,
iron, iron alloys, steel, stainless steel, hastelloy, inconel,
duranickel, indium, indium alloys, gold, gold alloys, silver,
silver alloys, copper, copper alloys, brass, nickel, nickel alloys,
platinum, platinum alloys, palladium, palladium alloys, zinc, zinc
alloys, cadmium and cadmium alloys.
[0063] In one embodiment, the extrusion material 16 can be drawn
over an inner die 14. The outer surface of the internal die can
have microstructures which cause microstructures to be imparted on
the inner surface of the extrusion material. In one embodiment, the
extrusion material is a tube with a central cavity.
[0064] The extrusion material can be drawn in a manner which will
reduce its diameter or its thickness or both after the extrusion
material leaves contact with the die. In one embodiment, the
extrusion material, having a cavity, can be drawn through drawings
die 15 which will reduce the diameter of the out perimeter, the
bore of the extrusion material or both.
[0065] In embodiments, one or more physical, mechanical or optical
properties, other than and/or in addition to hydrophobicity, are
established, varied and/or controlled by deforming a flexible
substrate having a plurality of microfeatures disposed thereon. In
an embodiment, for example, an optical property, such as the
reflectivity, wavelength distribution of reflected or scattered
light, transparency, wavelength distribution of transmitted light,
refractive index or any combination of these, is controlled by
flexing, bending, expanding, stretching and/or contracting the
flexible substrate having a plurality of microfeatures disposed
thereon. In an embodiment, a physical property, such as aerodynamic
resistance or hydrodynamic resistance is controlled by flexing,
bending, expanding, stretching and/or contracting the flexible
substrate having a plurality of microfeatures disposed thereon. In
an embodiment, a tactile property of the surface, such as the
surface's tactile sensation, is controlled by flexing, bending,
expanding, stretching and/or contracting the flexible substrate
having a plurality of microfeatures disposed thereon.
[0066] FIG. 2 illustrates that microstructures can be imparted on a
resulting part without necessarily changing the dimension of the
resulting part from that of the extrusion material. Therefore, the
negative microstructures on the die are imparted to the resulting
part in generally a 1:1 ratio. When the resulting part dimensions
are modified through the extrusion process, the ratio of size
between the extrusion material and the resulting part can be up to
7:1 and greater. In one embodiment, shape of the resulting part
produced from the die or mandrel can be preserved during the
drawing, or the shape can change. The shape preservation or shape
change can depend upon the properties of the extrusion material or
how the extrusion material is subsequently processed.
[0067] When the diameter size of the extrusion material is changed
after the microstructures are imparted on the resulting part, the
microstructures on the part are changed. Therefore, the
microstructures contained on the die are larger than that of the
resulting microstructures on the resulting part to account for the
shrinking of the resulting part from the extrusion material.
[0068] When the dimensions of the resulting part change from the
extrusion material, one embodiment has the resulting contact angle
of the microstructures on the die including in the range of 100
degrees to 120 degrees while the microstructures of the resulting
part are between 101 degrees and 170 degrees. When the dimensions
of the resulting part change is from the extrusion material, one
embodiment has the resulting friction properties of the resulting
part being 20 times less than the friction properties of the
microstructures on the die. One embodiment has the resulting
friction properties of the resulting part being 100 times more that
the friction properties of the microstructure on the die. When the
dimensions of the resulting part change from the extrusion
material, one embodiment has the microstructures on the die on a
scale of mm or .mu.m while the microstructures on the resulting
part will generally be in the scale of .mu.m or nm.
[0069] Referring to FIG. 3, the location of microstructures on the
die can vary with the preferred embodiment placing the
microstructures at location 26a as shown. Referring to FIG. 4,
blank 16 can also be extruded with only a portion of the die having
a negative of a microstructure shown as 28. When the extrusion
material is forced across the die, the shape created by the
interaction with the die imparts on the resulting part and can
include microstructures. The blank can be manufactured into a
resulting part through extrusion including drawing the blank
through the die.
[0070] Referring to FIG. 5, outer surface of a resulting part is
shown as 30 having a space 32 between the microstructures. When the
extrusion material is drawn down the microstructures on the outer
surface are modified, the microstructures themselves and the space
between the microstructures is compressed as shown in drawn down
resulting part 34. The same effect is realized with microstructures
that are on the inner surface of the extrusion material as shown in
extrusion inner surface 36 and drawn down extrusion inner surface
38.
[0071] Referring to FIG. 6, the extrusion process is shown in
further detail. Feed stock 40 is placed in hopper 42. The feed
stock is then mixed and melted in extrusion chamber 44. The heated
feed stock is pumped or otherwise drawn out of the extrusion
chamber through a pump or gears 46 and forced through a dye,
mandrel or both shown as 48. The extrudate produced by the dye or
mandrel, having microstructures, can then be cooled by a cooling
assembly 50 such as an air blower or quench bath, cut by cutter 52
or rolled on a spool 54. In the event that the spool rotates at a
faster speed then the extrudate exits the die, the extrudate can be
drawn to a smaller cross-section dimension.
[0072] It should be noted that there can be a plurality of quench
baths using various quenching solutions. For example, when
extruding aluminum, a quench bath of salt followed by a quench bath
of water can be used. The temperature of the quench baths, the time
between the extrudate exiting the dye and entering the quench bath
and the length of time the extrudate is in the quench bath can
vary.
[0073] In one embodiment, a puller 54 having an upper belt drive 56
and a lower belt drive 58 pulls the extrudate from the dye and into
the cutter or toward the spool. With a puller, the extrudate can be
drawn when the pull of the puller is greater than the extrusion
rate of the extrudate from the dye. This results in the extrudate
being stretched resulting in a smaller diameter extrudate.
Additionally, the extrudate can also shrink when the extrudate is
quenched and when the extrudate is rolled onto a spool.
[0074] Referring to FIG. 7, a portion of one microstructure of a
circular die is shown. The die 60 includes a plurality of
microfeatures 62 each having a first wall 64 and a second wall 66.
A channel 68 is defined in the die having a width 70. A first arc
72 can be included in a lower surface 74. A second arc 76 can also
be included in the lower surface overlapping the first arc. In use,
the die can produce an extrudate 78 having microstructures 80. It
should be noted that the extrudate microstructure is not a mirror
image of the die microstructures as the extrudate microstructures
have physical dimensions as the extrudate cools, is drawn or
otherwise physically altered after the leaving the extrusion die.
In one embodiment, the radius of the first arc is in the range of
45 to 65 .mu.m. The channel width is in the range of 150 to 250
.mu.m and the height 80 is in the range of 250 to 350 .mu.m. The
resulting extrudate microstructures can be between 7 and 13 .mu.m
in width and height can have generally a sloped peak
configuration.
[0075] Referring to FIG. 8, another microstructure is shown. A
lower surface 82 and a upper surface 84 are included in the die. A
first wall 86 and second wall 88 can be included in the
microstructure. An upper channel 85 can be defined on the upper
surface. The upper channel can include a concave portion 87. A
lower channel 90 can be defined in the microstructure having a
width 92 and a height 94. An arc 94 can be defined in the lower
surface. A second channel or arc 96 can be defined in the lower
surface. In one embodiment, the channel height is in the range of
0.8 to 1.6 mm and the height is in the range of 1.0 to 2.0 mm. The
resulting microstructures 98 on the extrudate can have a height in
the range of 70 to 90 .mu.m, a width in the range of 120 to 160
.mu.m and can also have a general slope shape.
[0076] Referring to FIG. 9, another microstructure is shown. A
first wall 100 is shown having an angle of incident .theta.' in
relation to the upper surface less than 90.degree. and an angle of
incident .theta.'' in relation to the upper surface greater than
90.degree.. A first arc 102 can be included in the lower surface
and a second arc 104 can be included in the lower surface adjacent
to the first arc. A channel 106 defined in said die can have a
width 106 that in one embodiment is in the range of 0.25 to 1.25 mm
and a height in the range of 0.25 to 1.25 mm. This arrangement of
the first wall, first arc, second arc and second wall is an
overhang microstructure. A peak 101 can be disposed between the
first and the second arc. During the extrusion process, the
extrudate microstructure can shrink through drawings, cooling or
other reason resulting in a extrudate microstructure that is
generally smaller than the original mirror of the die
microstructure. The height of the resulting extrudate
microstructure 110 can be in the range of 20 to 60 .mu.m and have a
width of between 100 and 140 .mu.m. A upper arc 108 can be included
in the upper surface. A wall angle of the extrudate can be at least
90.degree. in relation to the base of the pillar of the
microstructure.
[0077] In one embodiment, the sides of the resulting extrudate
microstructure are generally vertical. In another embodiment, the
walls can be slanted as shown in FIG. 10. The slanted walls can
result from a nylon extrudate manufactured with a line speed of 200
feet per second, drawn down about 3.2 times and cooled with a water
quench bath. The width 112 of the extrudate can be in the range of
150 to 250 .mu.m and the height can be in the range of 150 to 250
.mu.m. A wall angle of the extrudate can be at least 90.degree. in
relation to the base of the pillar of the microstructure. A channel
114 can be included in the upper surface of the die and can have
three sides of a generally trapezoidal shape. The resulting
extrudate microstructure could be a generally round microfeature
included on the extrudate. The microstructure can have a width in
the range of 1000 to 1400 .mu.m and a height in the range of 500 to
1000 .mu.m. The resulting extrudate can have a height in the range
of 90 to 210 .mu.m and a width in the range of 100 to 380 .mu.m. A
wall angle of the extrudate can be at least 90.degree. in relation
to the base of the pillar of the microstructure.
[0078] Referring to FIG. 11, a channel 120 can have a first wall
122, a second wall 124 and a arc 126 disposed at the lower surface
and between the first and second wall. The channel can have a width
in the range of 100 to 140 .mu.m and a height in the range of 200
to 360 .mu.m. The resulting extrudate microstructure 128 can have a
height between 45 to 60 .mu.m and a width of 40 to 50 .mu.m.
[0079] Referring to FIGS. 12 and 13, an extrusion die 130 includes
an opening 132 having microstructures. As shown, the die is a flat
die that can include one or more parts. Microstructures 134 are
disposed along the interior surface of the die. In one embodiment,
a first wall 136 has an angle of incident .theta.' that is less
than 90.degree., a first arc 138 adjacent to the first wall, a
planar portion 140, a second arc 142 and a second wall 144 having
an angle of incident .theta.'' greater than 90.degree.. The
resulting extrudate, shown in FIG. 14, is a film or otherwise flat
extrudate having microstructures 146 which are generally in the
range of 200 to 240 .mu.m apart with a height in the range of 30 to
40 .mu.m.
[0080] Referring to FIG. 15A, a circular die 150 is shown having
microstructures 152 disposed along an inner surface of the die.
Referring to FIG. 15B, one embodiment of the microstructure is
shown. Opening 154 is defined in the die with microstructure 156
surrounding the opening. The microstructures define a first arc 158
and a second arc 160 in an alternating pattern wherein the depth of
the first arc is greater than the depth of the second arc.
[0081] Referring to FIG. 16A, another microstructure for a circular
die is shown. The microstructure includes a first wall 162 having
an angle of incident .theta.' in relation to the upper surface of
less than 90.degree. and a second wall 164 having an angle of
incident .theta.'' in relation to the upper surface of greater than
90.degree.. A first arc 166 can be included in said microstructure
adjacent to a second arc 168. A lower planar surface 170 can in
included in the microstructure and disposed between the first and
second arc. An upper cavity 172 can be included in said upper
surface and can be arranged in an alternating pattern in said
microstructure.
[0082] Referring to FIG. 17, another microstructure for a circular
die is shown having a first wall 174 and a second wall 176 defining
a cavity 180 having a lower planar surface 178. In one embodiment,
the first and second wall have a height in the range of 400 to 480
.mu.m and a width in the range of 360 to 380 .mu.m. FIG. 18 shows a
upper arc 182 defined in the upper surface. In one embodiment, the
upper arc has a width in the range of 100 to 160 .mu.m and a depth
in the range of 100 to 160 .mu.m. FIG. 19 shows a lower arc 184
defined in the lower surface.
[0083] Referring to FIG. 20, another microstructure is shown having
a first wall and a second wall defining a cavity. A first arc 186
is defined in the lower surface and in the cavity. A pair of arcs
188a and 188b are defined in the walls of the cavity.
[0084] FIG. 21 shows a mandrel 190 having microstructures 200 so
that an extrudate made using the mandrel would have microstructures
formed on the inner surface of the extrudate. FIG. 22 shows that
the microstructures of the mandrel have a height 202.
[0085] FIG. 22A shows an extrudate 210 manufactured with a mandrel
that does not include microstructures. The inner surface 212 is
smooth resulting from a mandrel that does not include
microstructures. FIG. 22B, however, shows an extrudate 214 having
microstructures 216 that are formed on the inner surface 218 by a
mandrel which includes microstructures. FIG. 22C shows a mandrel
220 in one embodiment having a first circular portion 222 and a
second circular portion 224 that are adjacent to each other.
Microstructures 226 are located at the junction 228 between the
circular portions. Smooth portion 230a and 230b are located on the
respective circular portions as shown in FIG. 22D.
[0086] The terms and expressions which have been employed are used
as terms of description and not of limitation, and there is no
intention in the use of such terms and expressions of excluding any
equivalents of the features shown and described or portions
thereof, but it is recognized that various modifications are
possible within the scope of the invention claimed. Thus, it should
be understood that although the present invention has been
specifically disclosed by preferred embodiments and optional
features, modification and variation of the concepts herein
disclosed may be resorted to by those skilled in the art, and that
such modifications and variations are considered to be within the
scope of this invention as defined by the appended claims.
* * * * *