U.S. patent application number 16/533996 was filed with the patent office on 2019-12-26 for method of making a nozzle.
This patent application is currently assigned to 3M Innovative Properties Company. The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Barry S. Carpenter, John C. Clark, Michael R. Gorman, Raymond P. Johnston, Haiyan Zhang, Jun-Ying Zhang.
Application Number | 20190388911 16/533996 |
Document ID | / |
Family ID | 47192154 |
Filed Date | 2019-12-26 |
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United States Patent
Application |
20190388911 |
Kind Code |
A1 |
Zhang; Jun-Ying ; et
al. |
December 26, 2019 |
METHOD OF MAKING A NOZZLE
Abstract
Methods of making nozzles are disclosed. More specifically,
methods of making nozzles that may be used as components of a fuel
injection system are disclosed.
Inventors: |
Zhang; Jun-Ying;
(Perrysburg, OH) ; Gorman; Michael R.; (Lake Elmo,
MN) ; Zhang; Haiyan; (Woodbury, MN) ;
Johnston; Raymond P.; (Lake Elmo, MN) ; Carpenter;
Barry S.; (Oakdale, MN) ; Clark; John C.;
(Maplewood, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
47192154 |
Appl. No.: |
16/533996 |
Filed: |
August 7, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14354669 |
Apr 28, 2014 |
10406537 |
|
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PCT/US2012/063066 |
Nov 1, 2012 |
|
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16533996 |
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61554561 |
Nov 2, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23P 15/16 20130101;
B81C 2201/034 20130101; Y10T 29/4998 20150115; F02M 61/184
20130101; B81C 99/0085 20130101; B81B 2203/0353 20130101; Y10T
29/49432 20150115; B05B 1/14 20130101; F02M 61/1833 20130101; F02M
61/168 20130101; F02M 2200/8069 20130101; Y10T 29/49433
20150115 |
International
Class: |
B05B 1/14 20060101
B05B001/14; B23P 15/16 20060101 B23P015/16; B81C 99/00 20060101
B81C099/00 |
Claims
1. A method of fabricating a nozzle comprising the steps of:
forming a first microstructured pattern in a first material, the
first microstructured pattern comprising a plurality of discrete
microstructures; deforming at least one of the plurality of
discrete microstructures, resulting in at least one deformed
discrete microstructure; replicating the first microstructured
pattern in a second material different than the first material to
make a replicated structure; processing the replicated structure
into a nozzle having a plurality of through-holes in the second
material and corresponding to the plurality of microstructures in
the first microstructured pattern, said processing comprising
removing the first material from the replicated structure.
2. The method of claim 1 wherein said forming comprises casting and
curing the first material.
3. The method of claim 1 wherein said forming comprises extruding
the first material.
4. The method of claim 1, wherein the first material comprises a
polymer and the second material comprises a metal.
5. The method of claim 1, wherein said processing further comprises
removing enough of the second material of the replicated structure
to expose tops of the microstructures in the plurality of
microstructures in the first microstructured pattern.
6. The method of claim 5, wherein said removing comprises
planarizing the second material.
7. The method of claim 1, wherein the second material comprises an
electroplating material, and said replicating comprises
electroforming the second material so as to cover over the first
microstructured pattern.
8. The method of claim 7, wherein said processing further comprises
removing enough of the second material from the replicated
structure to expose tops of the microstructures in the plurality of
microstructures in the first microstructured pattern.
9. The method of claim 1, wherein the second material comprises a
ceramic.
10. The method of claim 1, wherein the plurality of discrete
microstructures comprises a discrete microstructure that is at
least a portion of a three-dimensional rectilinear body.
11. The method of claim 10, wherein the three-dimensional
rectilinear body is an elongated prismatic structure.
12. The method of claim 1, wherein the plurality of discrete
microstructures comprises a discrete microstructure that is at
least a portion of a three-dimensional curvilinear body.
13. The method of claim 1, wherein said deforming comprises
deforming an array of the plurality of discrete microstructures,
resulting in an array of deformed discrete microstructures.
14. The method of claim 1, wherein said deforming comprises bending
or twisting, resulting in at least one bent or twisted discrete
microstructure.
15. The method of claim 1, wherein said deforming occurs by
mechanical, thermal or thermomechanical means.
16. The method of claim 1, wherein the plurality of discrete
microstructures of the first pattern comprise re-closeable
fasteners with posts or mushroom-shaped tops.
Description
FIELD
[0001] The present description relates to methods of making
nozzles. Specifically, the present description relates to methods
of making nozzles that may be used as components of a fuel
injection system.
SUMMARY OF THE INVENTION
[0002] In one aspect, the present description relates to a method
of fabricating a nozzle. The method involves a number of steps,
including a first step of casting and curing a first material in
order to form a first microstructured pattern in the first
material. The first microstructured pattern includes a plurality of
discrete microstructures. The casting and curing step may involve
casting a first material in a first cast, curing the first
material, and removing the material from the first cast. The method
further involves replicating the first microstructured pattern in a
second material different than the first material to make a
replicated structure. Next, the second material of the replicated
structure is planarized to expose tops of the microstructures in
the plurality of microstructures in the first microstructured
pattern. The method then includes removing the first material
resulting in a nozzle having a plurality of holes in the second
material and corresponding to the plurality of microstructures in
the first microstructured pattern.
[0003] In another aspect, the present description relates to
another method of fabricating a nozzle. The method includes the
first step of extruding a first material in order to form a first
microstructured pattern in the first material. The first
microstructured pattern includes a plurality of discrete
microstructures. The method further involves replicating the first
microstructured pattern in a second material different than the
first material to make a replicated structure. Next, the second
material of the replicated structure is planarized to expose tops
of the microstructures in the plurality of microstructures in the
first microstructured pattern. The method then includes removing
the first material resulting in a nozzle having a plurality of
holes in the second material and corresponding to the plurality of
microstructures in the first microstructured pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIGS. 1A-1E combine to create a flow chart of a method of
fabricating a nozzle according to the present description.
[0005] FIGS. 2A-2B illustrate an initial cast and cure step.
[0006] FIG. 3 is a diagram of an apparatus used to produce a
microstructured film by extrusion.
[0007] FIG. 4 is a schematic three-dimensional view of a
microstructure.
[0008] FIG. 5 is a schematic three-dimensional view of a
microstructure.
[0009] FIG. 6 is a perspective view of a film with a plurality of
microstructures.
[0010] FIG. 7 is a backlit photomicrograph of a fuel injector
nozzle produced according to Example 1.
[0011] FIG. 8 is a backlit photomicrograph of a fuel injector
nozzle produced according to Example 2.
[0012] FIG. 9 is a photomicrograph of an array of microstructures
according to Example 3.
DETAILED DESCRIPTION
[0013] Fuel injection is increasingly becoming the preferred method
for mixing fuel and air in internal combustion engines, as fuel
injection generally can be used to increase fuel efficiency of the
engine and reduces hazardous emissions. Fuel injectors generally
include a nozzle with a plurality of nozzle through-holes for
atomizing the fuel under pressure for combustion. Increasingly
stringent environmental standards require more efficient fuel
injectors. The search for more efficient fuel injectors has led to
investigation of a number of varying sizes and shapes of fuel
injector nozzles, such as those described in commonly owned and
assigned PCT Publ. No. WO 2011/014607, the entirety of which is
incorporated by reference herein in its entirety. In addition to
the search for optimally sized and shaped fuel injector nozzles,
has come the search for new methods of creating highly effective
nozzles. One such method begins with structurization using a use of
two-photon process described in PCT Publ. No. WO 2011/014607,
described above. The present description relates to other new and
effective methods of providing nozzles for use in high efficiency
fuel injectors.
[0014] The term "nozzle" will be used throughout this description.
It should be understood that the term "nozzle" may have a number of
different meanings in the art. In some specific references, the
term nozzle has a broad definition. For example, U.S. Patent
Publication No. 2009/0308953 A1 (Palestrant et al.), discloses an
"atomizing nozzle" which includes a number of elements, including
an occluder chamber 50. This differs from the understanding and
definition of nozzle put forth herewith. For example, the nozzle of
the current description would correspond generally to the orifice
insert 24 of Palestrant et al. In general, the nozzle of the
current description can be understood as the final tapered portion
of an atomizing spray system from which the spray is ultimately
emitted, see e.g., Merriam Webster's dictionary definition of
nozzle ("a short tube with a taper or constriction used (as on a
hose) to speed up or direct a flow of fluid." Further understanding
may be gained by reference to U.S. Pat. No. 5,716,009 (Ogihara et
al.) issued to Nippondenso Co., Ltd. (Kariya, Japan). In this
reference, again, fluid injection "nozzle" is defined broadly as
the multi-piece valve element 10 ("fuel injection valve 10 acting
as fluid injection nozzle . . . "--see col. 4, lines 26-27 of
Ogihara et al.). The current definition and understanding of the
term "nozzle" as used herein would relate to first and second
orifice plates 130 and 132 and potentially sleeve 138 (see FIGS. 14
and 15 of Ogihara et al.), for example, which are located
immediately proximate the fuel spray. A similar understanding of
the term "nozzle" to that described herein is used in U.S. Pat. No.
5,127,156 (Yokoyama et al.) to Hitachi, Ltd. (Ibaraki, Japan).
There, the nozzle 10 is defined separately from elements of the
attached and integrated structure, such as "swirler" 12 (see FIG.
1(II)). The above-defined understanding should be understood when
the term "nozzle" is referred to throughout the remainder of the
description and claims.
[0015] FIGS. 1A-1E provide a flow chart of one embodiment of a
method for fabricating a nozzle according to the present
description. FIG. 1A illustrates providing a first microstructured
pattern 110 in a first material 102. The first microstructured
pattern 110 includes a plurality of discrete microstructures 104.
Discrete microstructures have a height t.sub.1. In this first
embodiment the first microstructured pattern is formed by a cast
and cure process. A simplified diagram of one such process is
illustrated in FIG. 2A. A cast 200 with a negative of
microstructure pattern 110 is provided. A given volume of curable
material, in many cases a polymer, is cast into cast 200. In some
cases, the polymer may be a silicone, acrylic, rubber, or
fluoropolymer. Once the first uncured material 100 has been cast
into cast 200, it is cured by an appropriate method. For example,
in some embodiments, the first material 100 may be cured by thermal
curing, or potentially exposure to UV radiation. Other appropriate
curing methods known in the art, such as applying other forms of
radiation, may also be used. Once curing has occurred, the first
microstructured material 102 may then be removed from mold 200 as
shown in FIG. 2B. First microstructured material 102 will contain
microstructures 104 arranged in a first microstructured pattern
110. Typically, the mold and the cured first microstructured
material are separated physically (i.e., by carefully pulling them
apart without damaging the mold and/or the cured first
microstructured material). Separation may be accomplished manually
or via the use of suitable tools such as tweezers etc. The result
of these steps may provide for the microstructured material 102 of
FIG. 1A.
[0016] In another embodiment, the first material 102 of FIG. 1A
having first microstructured pattern 110, may be created by an
extrusion process. A close up view of exactly how the extrusion
process may operate is illustrated in FIG. 3. A film may be cast
between a pair of rollers that are spaced apart by a specific
dimension, as is illustrated in FIG. 3, where a film 302 is pulled
from a reservoir 301, through a die 300 by an extrusion roller 304.
The film 302 is nipped between the extrusion roller 304 and a
second roller 306. Where the film 302 has a surface structure, the
second roller 306 may be a pattern roller, provided with a
prescribed surface for embossing a pattern onto the film 302. For
example, where the film 302 is being manufactured as a prismatic
film, the second roller 306 is provided with a plurality of
prismatic structures 308 around its surface, which create
complementary impressions in the upper surface 312 of the film 302.
The pattern roller may have a diameter whose value lies in the
range 15 cm-60 cm. The extrusion roller 304 may also be provided
with an embossing pattern that is used to emboss a pattern onto the
lower surface 318 of the film. After passing between the rollers
304 and 306, the film 302 cools, for example in a cooler 320, and
maintains the patterns embossed on it by the rollers 304 and 306.
In the particular embodiment shown, the extrusion roller 304 has a
surface 316 that has random variations in height on the lower
surface of the film 318.
[0017] The upper roller 306 may be provided with many different
types of embossing patterns. Examples of embossing patterns that
may be used on the upper roller 306 include a prismatic pattern
that may correspond to, e.g., a brightness enhancement film, a
lenticular pattern for a lenticular film, a hemispheric pattern,
and the like. In addition, the prismatic structures on the upper
roller 306 may be arranged in a direction perpendicular to the
direction of rotation, around the circumference of the roller 306,
rather than in a direction parallel to the direction of rotation,
as shown in FIG. 3. The upper roller 306 may also be smooth to
provide a flat film surface, or may be provided with a surface for
embossing a pattern on the upper surface 312 of the film 302. The
surface of the extrusion roller 304 may potentially include an
irregular embossing pattern. After forming the plurality of
microstructures on surface 312, the sheet may be cut into more
manageable sized pieces and may serve as the first material 102
having first microstructured pattern 110 in FIG. 1A.
[0018] Besides prismatic or hemispheric shaped microstructures, a
number of other commercially available products with varying
microstructure patterns and shapes may be appropriate. For example,
the discrete microstructures 104 may be shaped such as re-closeable
fasteners with posts or mushroom-shaped tops. These structures may
be made by the processes shown in commonly owned and assigned U.S.
Pat. Nos. 5,845,375 and 6,132,660, which are incorporated by
reference herein.
[0019] Other approaches may be utilized to produce a film having
one or more structured surfaces, including embossing a sheet,
injection molding and compression molding. In one particular
approach, a film of embossable material, applied to a web, is
compressively held against a pattern surface to emboss the
complement of the pattern surface onto the film. The embossable
material may be a thermoplastic material, such as poly(ethylene
teraphthlate), polaymides such as nylon,
poly(styrene-acrylonitrile), poly(acrylonitrile-butadiene-styrene),
polyolefins such as polypropylene, and plasticized polyvinyl
alcohol. In such embodiments, the film may be cooled while being
held against the patterned surface in order to solidify the
material with the pattern embossed thereon. In a variation of this
approach, the embossable material may be a curable polymer that is
cured, or partially cured before the patterned surface is
removed.
[0020] As mentioned above, the first material 102 of FIG. 1A may be
an appropriate polymer, such as a silicone, acrylic, rubber or
fluoropolymer. In another sense, the first material 102 may be
understood as a hardcoat composition formed from the reaction
product of a polymerizable composition. As such, at times
throughout this description, the first material may be described as
a "hardcoat." Specifically, the first material 102 may be a
hardcoat composition formed from the reaction product of a
polymerizable composition comprising one or more urethane
(meth)acrylate oligomer(s). Typically, the urethane (meth)acrylate
oligomer is a di(meth)acrylate. The term "(meth)acrylate" is used
to designate esters of acrylic and methacrylic acids, and
"di(meth)acrylate" designates a molecule containing two
(meth)acrylate groups.
[0021] Oligomeric urethane (meth)acrylates may be obtained
commercially; e.g., from Sartomer under the trade designation "CN
900 Series", such as "CN981" and "CN981B88. Oligomeric urethane
(meth)acrylates are also available from Cytec Industries Inc.
(Woodland Park, N.J.) and Cognis (Monheim am Rhein, Germany).
Oligomeric urethane (meth)acrylates may also be prepared by the
initial reaction of an alkylene or aromatic diisocyanate of the
formula OCN--R.sup.3--NCO with a polyol. Most often, the polyol is
a diol of the formula HO--R.sup.4--OH, wherein R.sup.3 is a
C.sub.2-100 alkylene or an arylene group and R.sup.4 is a
C.sub.2-100 alkylene or alkoxy group. The intermediate product is
then a urethane diol diisocyanate, which subsequently can undergo
reaction with a hydroxyalkyl (meth)acrylate. Suitable diisocyanates
include alkylene diisocyanates such as 2,2,4-trimethylhexylene
diisocyanate. The urethane (meth)acrylate oligomer employed herein
is preferably aliphatic.
[0022] The urethane (meth)acrylate oligomer contributes to the
conformability and flexibility of the cured hardcoat composition.
In preferred embodiments, a 5 micron thick film of the cured
hardcoat composition is sufficiently flexible such that it can be
bent around a 2 mm mandrel without cracking.
[0023] In addition to being flexible, the hardcoat has good
durability and abrasion resistance. For example, a 250 micrometer
(5 mil) thick film of the cured hardcoat exhibits a change in haze
of less than 10% after commonly used oscillating sand abrasion
testing.
[0024] The kind and amount of urethane (meth)acrylate oligomer is
selected in order to obtain a synergistic balance of flexibility
and good abrasion resistance.
[0025] One suitable urethane (meth)acrylate oligomer that can be
employed in the hardcoat composition is available from Sartomer
Company (Exton, Pa.) under the trade designation "CN981B88". This
particular material is an aliphatic urethane (meth)acrylate
oligomer available under the trade designation CN981 blended with
SR238 (1,6 hexanediol diacrylate). Other suitable urethane
(meth)acrylate oligomers are available from Sartomer Company under
the trade designations "CN9001" and "CN991". The physical
properties of these aliphatic urethane (meth)acrylate oligomers, as
reported by the supplier, are set forth in Table 1 as follows:
TABLE-US-00001 TABLE 1 Physical Properties of Aliphatic Urethane
Meth(Acrylate) Oligomers Tensile Tg (.degree. C.) as Trade
Viscosity Strength Elongation determined by Designation Cps at
60.degree. C. (MPa) (%) DSC CN981 6190 7.67 81 22 CN981B88 1520
10.48 41 28 CN9001 46,500 22.72 143 60 CN991 660 37.08 79 27
[0026] The reported tensile strength, elongation, and glass
transition temperature (Tg) properties are based on a homopolymer
prepared from such urethane (meth)acrylate oligomer. These embodied
urethane (meth)acrylate oligomers can be characterized as having an
elongation of at least 20% and typically no greater than 200%; a Tg
ranging from about 0 to 70.degree. C.; and a tensile strength of at
least 6.89 MPa (1,000 psi), or at least 34.48 MPa (5,000 psi).
[0027] These embodied urethane (meth)acrylate oligomers and other
urethane (meth)acrylate oligomers having similar physical
properties that can usefully be employed at concentrations ranging
from at least 25 wt-%, 26 wt-%, 27 wt-%, 28 wt-%, 29 wt-%, or 30
wt-% based on wt-% solids of the hardcoat composition. When the
hardcoat composition further includes inorganic nanoparticles such
as silica, the total concentration of the urethane (meth)acrylate
oligomer is typically higher, ranging from about 40 wt-% to about
75 wt-%. The concentration of urethane (meth)acrylate oligomer can
be adjusted based on the physical properties of the urethane
(meth)acrylate oligomer selected.
[0028] The urethane (meth)acrylate oligomer is combined with at
least one multi(meth)acrylate monomer comprising three or four
(meth)acrylate groups. The multi(meth)acrylate monomer increases
the crosslinking density and thereby predominantly contributes the
durability and abrasion resistance to the cured hardcoat.
[0029] Suitable tri(meth)acryl containing compounds include
glycerol triacrylate, trimethylolpropane triacrylate, ethoxylated
triacrylates (for example, ethoxylated (3) trimethylolpropane
triacrylate, ethoxylated (6) trimethylolpropane triacrylate,
ethoxylated (9) trimethylolpropane triacrylate, ethoxylated (20)
trimethylolpropane triacrylate), pentaerythritol triacrylate,
propoxylated triacrylates (for example, propoxylated (3) glyceryl
triacrylate, propoxylated (5.5) glyceryl triacrylate, propoxylated
(3) trimethylolpropane triacrylate, propoxylated (6)
trimethylolpropane triacrylate), trimethylolpropane triacrylate,
pentaerythritol triacrylate, and tris(2-hydroxyethyl)isocyanurate
triacrylate.
[0030] Higher functionality (meth)acryl containing compounds
include ditrimethylolpropane tetraacrylate, ethoxylated (4)
pentaerythritol tetraacrylate, and pentaerythritol
tetraacrylate.
[0031] Commercially available cross-linkable acrylate monomers
include those available from Sartomer Company (Exton, Pa.) such as
trimethylolpropane triacrylate available under the trade
designation SR351, pentaerythritol triacrylate available under the
trade designation SR444, dipentaerythritol triacrylate available
under the trade designation SR399LV, ethoxylated (3)
trimethylolpropane triacrylate available under the trade
designation SR454, ethoxylated (4) pentaerythritol triacrylate,
available under the trade designation SR494, and
tris(2-hydroxyethyl)isocyanurate triacrylate, available under the
trade designation SR368.
[0032] The hardcoat may additionally comprise one or more
di(meth)acryl containing compounds. For example, the urethane
(meth)acrylate oligomer may be purchased preblended with a
di(meth)acrylate monomer such as in the case of CN988B88. Suitable
monomers include, for example, 1,3-butylene glycol diacrylate,
1,4-butanediol diacrylate, 1,6-hexanediol diacrylate,
1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol
diacrylate, alkoxylated aliphatic diacrylate, alkoxylated
cyclohexane dimethanol diacrylate, alkoxylated hexanediol
diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone
modified neopentylglycol hydroxypivalate diacrylate, caprolactone
modified neopentylglycol hydroxypivalate diacrylate,
cyclohexanedimethanol diacrylate, diethylene glycol diacrylate,
dipropylene glycol diacrylate, ethoxylated (10) bisphenol A
diacrylate, ethoxylated (3) bisphenol A diacrylate, ethoxylated
(30) bisphenol A diacrylate, ethoxylated (4) bisphenol A
diacrylate, hydroxypivalaldehyde modified trimethylolpropane
diacrylate, neopentyl glycol diacrylate, polyethylene glycol (200)
diacrylate, polyethylene glycol (400) diacrylate, polyethylene
glycol (600) diacrylate, propoxylated neopentyl glycol diacrylate,
tetraethylene glycol diacrylate, tricyclodecanedimethanol
diacrylate, triethylene glycol diacrylate, and tripropylene glycol
diacrylate.
[0033] Returning to FIG. 1A, once the first microstructured pattern
has been formed in first material 102 by either cast and cure
method of FIGS. 2A-B or the extrusion method shown in FIG. 3 using
the materials discussed above, the first microstructured pattern
110 is replicated. Looking at FIG. 1B, first, an optional seed
layer 106 may be applied on the microstructured surface. The top
surface 108 of first material 102 is metalized or made electrically
conductive by coating the top surface with a thin electrically
conductive seed layer 106 similar to seed layer.
[0034] Conductive seed layer 106 can include any electrically
conductive material that is desirable in an application. Exemplary
conductive materials include silver, chromium, gold and titanium as
well as conductive polymers such as polyacetylene, polyphenylene
vinylene, poly aniline, polythiphene and the like. In some cases,
seed layer 106 has a thickness that is less than about 100 nm, less
than about 50 nm, or less than about 40 nm, or less than about 30
nm, or less than about 20 nm.
[0035] Next, as schematically illustrated in FIG. 1C, seed layer
106 is used to electroplate first microstructured pattern with a
second material different than the first material resulting in a
layer 120 of the second material. In some cases, the electroplating
of first microstructured pattern 110 is continued until the minimum
thickness t.sub.2 of layer 120 is greater than t.sub.1, the height
of the microstructures 104 and, thereby, form blind holes in the
layer 120 with the microstructures 104. In some cases, height
t.sub.2 is substantially equal to height t.sub.1. Suitable second
materials for electroplating include silver, passivated silver,
gold, rhodium, aluminum, enhanced reflectivity aluminum, copper,
indium, nickel, chromium, tin, and alloys thereof. In other
embodiments, the second material may be a ceramic that is deposited
on first microstructured pattern. Such a ceramic material may be
formed, e.g., by a sol-gel process as described in commonly owned
and assigned U.S. Pat. No. 5,453,104, or by photocuring of a
ceramic-filled or pre-ceramic polymeric composition as described in
commonly owned and assigned U.S. Pat. Nos. 6,572,693, 6,387,981,
6,899,948, 7,393,882, 7,297,374, and 7,582,685, each of which is
herein incorporated by reference in its entirety. Such ceramic
materials may comprise, e.g., silica, zirconia, alumina, titania,
or oxides of yttrium, strontium, barium, hafnium, niobium,
tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanide
elements (i.e. elements having atomic numbers ranging from 57 to
71, inclusive), cerium and combinations thereof.
[0036] Next, top surface of 122 of layer 120 is ground until tops
112 of microstructures 104 are exposed. The grinding or polishing
can be accomplished using any grinding method that may be desirable
in an application. Exemplary grinding methods include surface
grinding and mechanical milling. In some cases, the first material
is softer than the second material. For example, in some cases, the
first material is polycarbonate and the second material is a nickel
alloy. In such cases, small portions of tops 112 can be removed
during the grinding process to ensure that the tops of all the
microstructures in first microstructured pattern 110 are exposed.
In such cases, the grinding results, as schematically illustrated
in FIG. 1D, in a layer 124 of the second material planarizing the
first microstructured pattern and exposing tops 112 of the
microstructures in the plurality of microstructures in the first
microstructured pattern. Layer 124 of the second material has a top
surface 126 that is substantially even with tops 112 of
microstructures 104. The microstructures have a height t.sub.3 that
can be slightly less than t.sub.1.
[0037] Although in FIGS. 1A-1D, the microstructures 104 are
illustrated as having flattened tops initially, this need not be
the case. In a number of embodiments the microstructures in the
initial step may have a peaked surface. This may be especially
appropriate as this portion of the microstructure may act as a
sacrificial portion that aids in providing optimal planarization
during the grinding step. A better understanding of this concept
may be understood by reference to commonly owned and assigned U.S.
patent Ser. No. 10/054,094, incorporated herein by reference in its
entirety.
[0038] Next, as illustrated in FIG. 1E, first material 104 is
removed, resulting in a layer 130 of the second material that
includes a plurality of through-holes 132 that correspond to the
plurality of microstructures in first microstructured pattern 110.
Holes 130 include hole entries 136 and hole exits 134. The layer
130 made up of second material and may be any of the appropriate
metals mentioned above, e.g. nickel, or may be, for example,
ceramic. Optionally, the individual microstructures, each bearing a
hole entry 136 and hole exit 134 may be singulated by dividing them
from one another along, e.g., lines 138. The individual
microstructures may then potentially be recombined in a desired
pattern by an appropriate means, such as laser welding. In other
embodiments, the microstructured pattern will be cast and cured or
go through the extrusion process such that the final pattern
matches that of the first material's first microstructured
pattern.
[0039] Typically, the first material and the second material that
includes plurality of holes are separated physically (i.e., by
carefully pulling them apart without damaging the mold and/or the
cured first microstructured material. Separation may be
accomplished manually or via the use of suitable tools such as
tweezers etc. It is also possible to remove the first material
chemically, for example, by dissolving the first material in a
suitable solvent such as acetone, ethyl alcohol, isopropyl alcohol
or the like. Alternately one may use an etchant such as an aqueous
solution of KOH. The first material and the second material may
also be separated thermally by melting or burning of the first
material at a suitable temperature without deforming, melting or
otherwise damaging the second material.
[0040] In some cases, the plurality of discrete microstructures
formed includes a discrete microstructure that is a
three-dimensional rectilinear body, a portion of a
three-dimensional rectilinear body, a three-dimensional curvilinear
body, a portion of a three-dimensional curvilinear body, a
polyhedron, a cone, or a tapered microstructure.
[0041] In some cases, a disclosed microstructure can be a
three-dimensional rectilinear body such as a polyhedron, such as a
tetrahedron or a hexahedron, a prism, or a pyramid, or a portion,
or a combination, of such bodies, such as a frustum. For example,
FIG. 4 is a schematic three-dimensional view of a microstructure
420 that is disposed on a substrate 410 and includes a planar or
flat base 430, a planar or flat top 440 and a side 450 that
connects the top to the base. Side 450 includes a plurality of
planar or flat facets, such as facets 460, 465 and 470.
Microstructure 420 can be used as a mold to fabricate holes for use
in, for example, a nozzle.
[0042] In some cases, a disclosed microstructure can be a
three-dimensional curvilinear body or a portion of such body, such
as a segment of a sphere, an asphere, an ellipsoid, a spheroid, a
paraboloid, a cone or a truncated cone, or a cylinder. For example,
FIG. 5 is a schematic three-dimensional view of a microstructure
520 that is disposed on a substrate 510 and includes a planar or
flat base 530, a planar or flat top 540 and a curvilinear side 550
that connects the top to the base. In the exemplary microstructure
520, top 540 and base 530 have the same shape. Microstructure 520
tapers narrower from base 530 to top 540. As a result, top 540 has
a smaller area than base 530. Microstructure 520 can be used as a
mold to fabricate holes for use in, for example, a nozzle.
[0043] In other cases, such as that shown in FIG. 6, the
microstructured pattern 610 of film 600 may contain a plurality of
microstructures 604 that are elongated. For example, as shown in
FIG. 6, the microstructures may be prisms that are elongated along
the length of the film L. In such a case once the tops of the
microstructures are ground, the opening corresponding to the hole
outlet may in fact be an elongated slit, such as where the tops of
the elongated prism is removed along dashed line 606.
[0044] The microstructures of the current description may be
understood as having a "diameter" of their opening at different
heights of the microstructure. The diameter may be understood as
the maximum distance between the edges of the microstructure at a
common height. In some embodiments the hole entry may have a
diameter of less than 300 microns, or of less than 200 microns, or
of less than or equal to 160 microns, or of less than 140 microns.
In some embodiments the hole exit may have a diameter of less than
300 microns, or less than 200 microns, or less than 100 microns, or
less than or equal to 40 microns, or less than 25 microns. As shown
in the Figures, the microstructures disclosed herein that serve as
nozzles may be monolithic structures. In other words, the
microstructures that form the actual nozzles are created from, and
ultimately form a common, single piece of material. This may be
understood as different from nozzles that are formed through a
combination of a number of different parts, where such parts are
potentially made up of different materials. In this regard, as
shown in the above-mentioned figures, the nozzles disclosed herein
may be monolithic structures.
[0045] In some cases, a microstructure can be intentionally
deformed (i.e., bent, twisted etc.). Such deformation can be used
to affect the flow of fluids thorough the nozzles made using these
microstructures. More specifically, by deforming the
microstructures, the resulting nozzles may direct the flow of
fluids in a desired direction or may lead to a desired
angular/volumetric distribution of the fluids in the combustion
chamber. Such deformation of the microstructures may be
accomplished by thermal means, mechanical means or thermomechanical
means. For example, the microstructured first material may be
heated to soften and potentially even partially melt the
microstructures causing them to deform under the influence of
gravity or other mechanical forces. In another embodiment, the
microstructures are physically bent by the action of a mechanical
force on them at an angle. Some examples of potential applications
of mechanical force include squeezing the microstructures between
the mandrels of a vice or forcing them through a gap narrower than
the height of the microstructures. In yet another embodiment,
microstructures in the form of microposts may be contacted by a
force applied along a plane orthogonal to the height of the
structures, where the force acts downward (in the direction of the
height of the microstructures. This force applied along the tops of
the microstructures may be applied with a hot object at a
temperature above the melting point of the first material,
resulting in the melting the tips of the microposts and forming
mushroom shaped microstructures. When the nozzles are made from the
mushroom shaped microstructures by the method of the invention, the
tops of the mushroom shaped microstructures lead to large cavities
at the inlet side of the resulting nozzles. Such cavities may act
as occlude chambers in a nozzle application.
[0046] In yet another embodiment, arrays of microstructures may be
deformed. All or some of the individual microstructures in an array
may be deformed. In some cases some of the microstructures are
deformed in one pattern while others are deformed in a second
pattern. It is possible to have each individual microstructure
within the array be deformed in a predetermined relation to the
neighboring microstructures.
EXAMPLES
[0047] Objectives and advantages of this invention are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this invention. These examples are merely for illustrative purposes
only and are not meant to be limiting on the scope of the appended
claims. Unless otherwise noted, all chemicals were obtained from,
or are available from chemical suppliers such as Sigma-Aldrich
Chemical Company, St. Louis. Mo.
Example 1
[0048] A microstructured film was prepared by following the general
method described in U.S. Pat. No. 5,845,375 (Miller et. al.). An
ethylene-propylene copolymer (available from Dow Chemical Co.
[Midland, Mich.] under the trade designation "C700-35N") resin was
melted in a 45 millimeters twin screw extruder at a temperature of
230.degree. C. and the extruded melt was passed through a die to
form a film. The resulting film, being about 0.15 millimeters in
thickness, and having a basis weight of 120 g/m.sup.-2, was pressed
against a microstructured tooling by feeding it through a pair of
rollers. The microstructured tooling was mounted onto one of the
rollers and chilled to about 90-120.degree. C. (194-248.degree.
F.). The roller with the microstructured tooling was rotated at a
surface speed of 0.33 m/s. The microstructure on the surface of the
tooling comprised cavities (i.e., prismatic holes) of approximately
120 micrometer sides and 370 micrometer deep. The vacancies were
arranged in a linear pattern along the x and y direction on the
surface of the tooling approximately 520 micrometer apart. When the
extruded film was pressed against the microstructured tooling by
the action of the second roller, the pattern of microstructures was
replicated in the extruded polypropylene film. The resulting
polypropylene film (i.e. the replica) exiting the pair of rollers
had posts (corresponding to the cavities on the surface of
microstructured tooling) projecting from the film surface. The
resulting microstructured film contained posts of approximately 120
micrometer sides and 370 micrometer depth. The vacancies were
arranged in a linear pattern along the x and y direction on the
surface of the tooling approximately 520 micrometer apart
[0049] Next, the microstructured film was electroplated with Ni
following the general electroplating processes well known in the
art. A general description of the electroplating art can be found,
for example, in "Modern Electroplating", Fourth Edition, 2002, John
Wiley & Sons, editors: Mordechav Schlesinger and Milan
Paunovic. A circular (about 3 millimeter in diameter) section of
the microstructured film produced above was cut out and was adhered
on a stainless steel disc with the aid of a double stick tape. The
surface of the film was made conductive by depositing a thin Ag
film (seed layer) on the microstructured film replicas by e-beam
evaporation. The process of depositing thin layer of Ag is referred
to as silver mirror reaction in the electroplating art. Nickel was
electrodeposited on the Ag coated surface of the microstructured
film to replicate the microstructures. Nickel electrodeposition was
carried out in a nickel sulfamate bath at a pH range of 3.5-4.5 at
a temperature of 54.5.degree. C. The solution contained a 0.2% of
sodium dodecyl sulfate surfactant. Nickel electrodeposition was
carried out in four stages. In the first stage, which lasted
approximately 6 hours, the current density was approximately 27
Amperes/m.sup.2. The second stage lasted 4 hours and featured a
current density of 54 Amperes/m.sup.2, and the third stage lasted 4
hours and featured a current density of 108 Amperes/m.sup.2. The
fourth stage was 34 hours at a current density of 216
Amperes/m.sup.2. Nickel electrodepositing was completed when the
thickness of nickel reached about 500 micrometers.
[0050] After the electrodeposition was completed, the resulting
nickel replica with the microstructured film still in place was
planarized and fine-polished to remove enough material so that the
holes in the nickel replica were open and free of burrs. This was
accomplished by first attaching the Ni-plated microstructured film
using a wax on a grinding fixture (with the microstructured film
down) of a grinder/polisher (available from Ultra Tec
Manufacturing, Inc. [Santa Ana, Calif.]). Extreme care was taken to
ensure that the Ni-plated microstructured film was positioned
parallel to the surface of grinding fixture. The fixture was
mounted on the polisher and then the Ni-plated microstructured film
was planarized and ground using 100, 150, and 220 grit size
abrasive films, sequentially. The grinding continued until a
sufficient amount of Ni was removed, exposing the tops of posts of
the microstructured polymer. The level of grinding to be done was
determined based on the desired opening size of the resulting
nozzle. The Ni-plated microstructured film was then polished
sequentially using 9, 6, and 3 micrometer diamond lapping films.
Finally the microstructured film was separated from the polished
(nickel) nozzle. The nozzle had square sided holes with
approximately 120 micrometer sides. The nozzle holes were arranged
in a linear pattern along the x and y direction on the surface of
the tooling approximately 520 micrometer apart. A backlit
photomicrograph of the nickel fuel injector nozzle of Example 1 in
provided in FIG. 7.
Example 2
[0051] Example 2 was prepared in generally the same manner as
Example 1. For Example 2, a low density polyethylene (LDPE) film
was provided (about 580 micrometers in thickness, prepared from
TENITE 18 DOA (obtained from Eastman Chemical Company [Kingsport,
Tenn.] under trade designation "TENITE 18"), with 0.5% surfactant
TRITON X100 (obtained from Dow Chemical Company [Midland, Mich.]
under trade designation "TRITON X100") and minor quantities of
TiO.sub.2 pigment to make the film white in appearance. The general
methods of making structured surfaces, and in particular
microstructured surfaces, on a polymeric layer such as a polymeric
film are disclosed in U.S. Pat. Nos. 5,069,403 and 5,133,516, both
to Marentic et al., the relevant portions of which are hereby
incorporated by reference. U.S. Pat. No. 5,514,120 to Johnston et
al. describes how the tooling was created to microreplicate the V
shaped film described herein. The microstructures on the surface of
the tooling included linear, V-shaped groves running parallel to
one another. The V-shaped groves had a height of 460 micrometers
and 410 micrometer pitch. When the extruded film was pressed
against the microstructured tooling by the action of the second
roller, the microstructure was replicated in the extruded film. The
resulting LDPE microstructured film (i.e. the replica) exiting the
pair of rollers had V-shaped groves of same size as the
microstructured tooling
[0052] Next, the resulting microstructured film was electroplated
with Ni, planarized and polished using the same process described
above for Example 1.
[0053] The nozzle of Example 2 had rectangular openings. A backlit
photomicrograph of the nickel fuel injector nozzle of Example 2 is
provided in FIG. 8.
Example 3
[0054] In this example, hollow micro-needle arrays made of
polycarbonate were used as the microstructured first material. The
micro-needle arrays were prepared using the general processes
described in commonly owned and assigned US Patent Publication No.
US2009/009537 (DeVoe, et. al.). Each array had 18 micro-needles
that were 900 micrometers tall and a tapered cone with a large,
fixed end that was approximately 270 micrometers in diameter. The
micro-needles were similar in shape to those shown in FIG. 10 of US
Patent Publication No. US2009/009537 (DeVoe, et. al.). The conical
shape made it easy to bend the needles near the top. The goal was
to deform all of the micro-needle tips by bending them so that they
"pointed" in an off-axis direction. The total height of the
substrate plus the micro-needles was approximately 2.52 millimeter
(0.099 inch). A gap between the smooth jaws of a miniature tooling
vise was set to about 2.159 millimeters (0.085 inches). Once the
gap was set, the polycarbonate micro-needle array was pressed by
hand through the gap. All of the needles in the array were bent by
a similar amount. FIG. 9 is a photomicrograph of the deformed
micro-needle arrays illustrates the results of bending the
micron-needles over. While in this Example 3, the vise jaws were
set parallel to each other; they did not need to be parallel. A
non-parallel gap in the cross-web direction would result in the
needles on one side of the substrate being bent more than the
needles on the other.
[0055] The deformed microneedle pre-form was then silver sputtered,
nickel electro-plated and backside ground using exactly the same
processes used in Example 1 above.
Example 4
[0056] Example 4 was prepared in generally the same manner as
Example 3, except that the micro-needle arrays were deformed by
pressing an aluminum cylindrical rod on the center of the
micro-needle array. The deformed micro-needles were bent at their
tips so as to point outward from the center of the array in a
circular arrangement.
[0057] The deformed microneedle pre-form was then silver sputtered,
nickel electro-plated and backside ground using exactly the same
processes used in Example 1 above.
* * * * *