U.S. patent application number 10/938058 was filed with the patent office on 2005-02-10 for apparatus and method for forming a spiral wound abrasive article, and the resulting article.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Follensbee, Robert A., Hawkins, Ann M., Heacox, Gary L., Hunt, Douglas C., Yoos, Stephen J..
Application Number | 20050032468 10/938058 |
Document ID | / |
Family ID | 32068257 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050032468 |
Kind Code |
A1 |
Hunt, Douglas C. ; et
al. |
February 10, 2005 |
Apparatus and method for forming a spiral wound abrasive article,
and the resulting article
Abstract
An apparatus and method for forming an endless spiral wound
abrasive article and the resulting article. The apparatus includes
first and second spaced-apart hubs, configured so that a portion of
first and second webs passing between the first hub and the second
hub is oriented substantially in a plane which remains stationery
even if a position of a hub is changed. The apparatus further
includes winders and a web joiner. The method includes providing a
second web which includes an adhesive disposed on a first surface
and a liner releasably affixed to the adhesive. The method includes
removing the liner from the second web before positioning the
second web adjacent the first web. The first and second webs are
wound about the first and second hubs to form a spiral wound
article having a desired circumference.
Inventors: |
Hunt, Douglas C.; (Miltona,
MN) ; Hawkins, Ann M.; (Lake Elmo, MN) ;
Heacox, Gary L.; (Zimmerman, MN) ; Follensbee, Robert
A.; (Oakdale, MN) ; Yoos, Stephen J.;
(Andover, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
32068257 |
Appl. No.: |
10/938058 |
Filed: |
September 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
10938058 |
Sep 10, 2004 |
|
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10262611 |
Oct 1, 2002 |
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6805722 |
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Current U.S.
Class: |
451/535 |
Current CPC
Class: |
B24D 11/06 20130101;
B24D 18/0036 20130101; B24D 9/006 20130101 |
Class at
Publication: |
451/535 |
International
Class: |
B24D 011/00 |
Claims
1. An apparatus for forming a spiral wound endless abrasive article
comprising: a first hub having a longitudinal axis and a convex
outer surface; a first winder adapted to introduce a first web to a
web joiner; a second winder adapted to introduce a second web onto
the first hub and to the web joiner; the web joiner adapted to join
abutting edges of the first web by overlap of the second web as the
first and second webs spirally wind about the first hub to form a
spiral wound article, the first and second webs positioned in an
offset and overlapping configuration; and a second hub at a
distance from the first hub, the first and second webs passing
around the second hub while spirally winding about the first hub to
produce a spiral wound article having a desired circumference;
wherein the first hub and the second hub are configured so that a
portion of the first and second webs passing from the first hub to
the second hub is oriented substantially in a stationary plane.
2. The apparatus of claim 1 wherein the first hub is supported in a
cantilevered configuration.
3. The apparatus of claim 2 wherein the second hub is supported in
a cantilevered configuration.
4. The apparatus of claim 1 wherein the second hub is adjustably
supported.
5. The apparatus of claim 4 wherein adjustment of the second hub
does not change the plane.
6. The apparatus of claim 1 further comprising: a driving mechanism
intermediate the first hub and the second hub.
7. The apparatus of claim 1, wherein the plane is substantially
vertical.
8. The apparatus of claim 1, further comprising a heating element
intermediate the first hub and driving mechanism.
9. The apparatus of claim 8, wherein the spiral wound article
comprises a first and second opposed major surfaces; and wherein
the heating element heats both the first major surface and the
second major surface of the spiral wound article.
10. The apparatus of claim 8, wherein the heating element is an
infrared heater.
11. The apparatus of claim 1, wherein the first web and second web
are adhered at the overlap of the first web and the second web.
12. The apparatus of claim 1, wherein the first web is a coated
abrasive.
13. The apparatus of claim 1, wherein the second web is a
prelaminated adhesive backing material comprising: a backing layer
having first and second opposed major surfaces; the first major
surface comprising an adhesive; and a liner layer releasably
attached to the first major surface of the backing material by the
adhesive.
14. The apparatus of claim 13 further comprising a slip layer
applied to the second major surface of the backing layer.
15. The apparatus of claim 13 further comprising a third winder
adapted to accept the liner layer from the second web as the second
web is unwound from the second winder.
16. The apparatus of claim 1 further comprising a third winder
adapted to introduce a third web onto the first hub, the third web
positioned in an offset and overlapping configuration relative to
the second web.
17. The apparatus of claim 16, wherein the first web comprises a
coated abrasive, the second web comprises an adhesive material, and
the third web comprises a reinforcing material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 10/262,611, filed Oct. 1, 2002, now allowed.
BACKGROUND OF THE INVENTION
[0002] Endless coated abrasive articles, such as belts, sleeves and
tubes are used in a variety of abrading operations, especially in
the woodworking and metal finishing industries. These operations
typically require that the articles be made and supplied by the
coated abrasive manufacturer in a large variety of widths and
circumferences.
[0003] Techniques for making endless coated abrasive belts are
known in the art and include those utilizing lap joints and butt
splices. Lap joints can be provided, for example, by cutting a
coated abrasive material into an elongate strip of a desired width
and length. The two free ends of the elongate strip are
respectively beveled to have a top end and a bottom end which can
be superposed to form a joint. The beveled ends are then overlapped
and joined adhesively or mechanically. Butt splices can be
provided, for example, by mating the two free ends of the elongate
strip into a juxtaposed relationship at a juncture line. The bottom
surface of the backing at each end of the elongate strip is then
coated with an adhesive, mechanically secured, or otherwise
attached, and may be overlaid with a strong, thin, tear-resistant,
splicing media in the joint area. The endless coated abrasive belt
may, for example, be subsequently slit into narrower widths.
[0004] Coated abrasive belts in widths greater than the width of
the coated abrasive material have been produced by a number of
methods. One such method involves piecing together segments of
coated abrasive material to form wide, multi-jointed sectional
belts that cover a broad range of belt widths and belt
circumferences. These belts, however, have the drawback of
increased cost due to the multiple piecing and joining processes
required to fabricate the belts. In addition, multiple joints
increase the potential for problems due to weakening of the belt at
the joints, as well as process control and quality issues.
[0005] Another method of forming an endless coated abrasive belt
that has a width greater than the width of coated abrasive material
from which it was made involves spiral winding of material. A
conventional method for making such "spiral wound" belts involves
winding an inner liner spirally on a mandrel having an outer
circumference equal to the inside circumference of the desired
abrasive belt, applying an adhesive to the outer major surface of
the inner liner, and winding spirally over the adhesive layer a
strip of coated abrasive material. Such a method is widely used for
the fabrication of belts in smaller sizes, up to, for example, 6
inches (15.2 cm) in diameter or 19 inches (48.3 cm) in
circumference.
[0006] Another such method involves spiral winding narrow strips of
coated abrasive material having scarfed (or angle cut) edges that
overlap and are adhered using conventional techniques. Also, the
edges of a piece of wider coated abrasive material may be formed to
abut when wound spirally within a revolvable drum. Subsequently, a
resinous coating material is applied to the inner periphery of the
belt which then spreads, as the drum revolves, to form a continuous
layer of resinous coating that joins the belt material together.
Yet another method involves spiral winding about a mandrel a coated
abrasive material with abutting edges that has a flexible backing
material including a layer of hot-melt adhesive. The spiral wound
material is then heated to cause the hot-melt adhesive to flow
across the abutted edges, resulting in a continuous layer that
secures the edges together.
[0007] An ongoing need exists for spiral wound abrasive belts that
are produced in a faster, cheaper and more efficient manner, and in
a variety of sizes. Such spiral wound belts that take advantage of
abrasive media constructions that produce stronger and more durable
abrasive articles are also desirable.
BRIEF SUMMARY OF THE INVENTION
[0008] Aspects of the present invention include an apparatus and
method for forming an endless spiral wound abrasive article and the
resulting article. The apparatus includes first and second
spaced-apart hubs, configured so that a portion of first and second
webs passing between the first hub and the second hub is oriented
substantially in a plane which remains stationery even if a
position of one of the hubs is changed. The apparatus further
includes winders and a web joiner. The method includes providing a
second web which includes an adhesive disposed on a first major
surface and a liner releasably affixed to the adhesive. The method
includes removing the liner from the second web before positioning
the second web adjacent the first web. The first and second webs
are wound about the first and second hubs to form a spiral wound
article having a desired circumference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of one embodiment of a spiral
wound abrasive belt formed in accordance with the present
invention.
[0010] FIG. 2 is a plan view of an abrasive media including two
webs for use in the formation of the spiral wound abrasive belt of
FIG. 1.
[0011] FIG. 3 is a partial cross-sectional view of the spiral wound
abrasive belt of FIG. 1.
[0012] FIG. 4 is partial cross-sectional view of a second
embodiment of a spiral wound abrasive belt formed from an abrasive
media including three webs.
[0013] FIG. 5 is a partial cross-sectional view of a third
embodiment of a spiral wound abrasive belt formed from an abrasive
media including three webs.
[0014] FIG. 6 is a partial cross-sectional view of a fourth
embodiment of a spiral wound abrasive belt formed from an abrasive
media including three webs.
[0015] FIG. 7 is a perspective view of one embodiment of a spiral
wound abrasive belt forming apparatus.
[0016] FIG. 8 is a partial end view of the apparatus of FIG. 7.
[0017] FIG. 9 is a diagram illustrating another embodiment of a
spiral wound abrasive forming apparatus.
[0018] FIG. 10 is a diagram illustrating a method for forming an
exemplary spiral wound abrasive using a forming apparatus.
[0019] FIG. 11 is a partial cross-sectional view of a fifth
embodiment of a spiral wound abrasive belt formed from an abrasive
media including two webs.
[0020] FIG. 12 is a diagram illustrating yet another embodiment of
a spiral wound abrasive forming apparatus.
[0021] While the above-identified drawings set forth several
embodiments of the present invention, other embodiments of the
present invention are also contemplated, as noted in the
discussion. This disclosure presents illustrative embodiments of
the present invention by the way of representation and not
limitation. These representations are not to scale. Numerous other
modifications and embodiments can be devised by those skilled in
the art which fall within scope and spirit of the principles of
this invention.
DETAILED DESCRIPTION
[0022] With reference to the attached drawings, it is to be
understood that like components are labeled with like numerals
throughout the several drawings. FIG. 1 is a spiral abrasive belt
100 formed in accordance with the present invention for use on a
polisher, sander, grinder or other rotating machine. The spiral
belt 100 has a width 102 and a circumference 103. The spiral belt
100 also has first and second belt ends 104 and 105, respectively,
an inner major surface 108 and an outer major surface 110. The
inner and outer major surfaces 108, 110 are in some embodiments
preferably continuous such that there is no appreciable beginning
or end to the belt 100 while it rotates over a surface being
processed.
[0023] FIG. 2 is an abrasive media 80 that may be used to form the
spiral belt 100, in accordance with the present invention. The
abrasive media 80 includes a first web 50 having a width 56 and
first and second side edges 52, 54. In some embodiments, first and
second side edges 52, 54 are preferably parallel to one another. As
shown, the abrasive media 80 also includes a second web 60 that has
a width 68 and parallel first and second side edges 62 and 64,
respectively. The first web 50 overlaps a first portion 65 of the
second web 60 along the length leaving a second portion 66 of the
second web 60 exposed. As shown, the second portion 66 is sized to
about one-half the width 68 of the second web, although it may be
smaller or larger if desired.
[0024] The abrasive media 80 has a first end 82 formed or cut at an
angle 84 to the web side edges 52, 54, 62, 64. The angle 84 and
thus the length 86 of the first end 82 may vary depending on the
desired dimensions of the spiral belt 100. In one embodiment, the
first end length 86 determines the circumference 103 of the spiral
belt 100, so that changes in angle 84 and length 86 will provide
larger or smaller belts as desired for a particular application. In
another embodiment, a pre-cut angled edge 84 is not needed. The
resulting spiral belt 100 may be trimmed as needed to provide an
even first belt end 104. In this embodiment, the angle of winding
and width 56 of the first web 50 (as discussed in more detail
below) determine the resulting circumference 103 of the spiral belt
100.
[0025] The abrasive media 80 may be configured as a continuous web,
thereby forming a spiral belt 100 of ever increasing width, which
may then be slit to a desired belt width 102. The abrasive media 80
may also be configured to include a second end 88, as shown in FIG.
1, formed parallel to the first end 82, giving the abrasive media
80 a fixed length (not shown). The length of the abrasive media 80
then determines the width 102 of the spiral belt 100.
[0026] The spiral belt 100 is formed by winding the abrasive media
80 in a spiral wherein side edge 52 is brought into abutting
contact with side edge 54, such that no apparent or appreciable gap
is present. In some embodiments, any gap is preferably less than
about {fraction (1/32)} inch (0.08 cm) wide. The angle 84 sets the
angle of wrap for the spiral belt 100. The angled first end 82
provides a starting point at first tip 83 for the spiral belt 100,
as well as the relatively even first belt end 104. In a like
manner, the angled second end 88 provides an end point at tip 89
for the spiral belt 100 and second belt end 105 that is also
relatively even. The resulting spiral belt 100 has width 102. In
some embodiments, the first and second belt ends 104, 105 are both
configured to be generally perpendicular to the width dimension 102
and generally parallel to each other. For continuous width belts,
the second belt end 105 may be formed by slitting the belt 100 at
the desired width 102, instead of by a second end 88. Tabs 109 may
be provided to secure the angled first and second end tips 83 and
89 to the remainder of the spiral belt 100.
[0027] As the abrasive media 80 winds to form the spiral belt 100,
the first web 50 overlaps the exposed second portion 66 of the
second web 60. FIG. 3 is a partial cross-sectional view of wound
spiral belt 100 showing the resulting relationship between the
first and second webs 50 and 60, respectively. In some embodiments,
the second web 60 includes an adhesive over the second portion 66,
which facilitates joining with the first web 50 during the winding
to produce the spiral belt 100.
[0028] The second web 60 may be provided as a narrow strip whose
width 68 is appreciably narrower than width 56 of the first web 50,
as shown in FIGS. 2 and 3, functioning primarily for the purpose of
joining the abutting edges 52 and 54 of the first web 50. As shown
in FIG. 4 in a second embodiment of a spiral belt 100' formed from
an abrasive media 80', a second web 60' may also be provided in a
larger width 68' up to and including a width 56' of a first web
50', positioned an offset amount 66' from the first web 50'. As
shown, the offset amount 66' is substantially less than one-half
the width 68' of the second web 60', however it may be smaller or
larger if desired. The second web width 68' should be no greater
than the first web width 56' or else first web edges 52' and 54'
will not abut, but will have a gap between them. If the edges 52',
54' did abut without a gap, there would be a bump running around
belt 100' where the second web 60' overlaps itself. When the second
web width 68' is about equal to the first web width 56', the second
web side edges 62' and 64' will also abut without an appreciable
gap in a manner similar to the side edges 52', 54' of the first web
50'. In some embodiments of the exemplary spiral belt in accordance
with the present invention, the second web 60' also includes
adhesive over the offset portion 66' (applied to either the first
or second webs 50', 60') to facilitate joining of the second web
60' to the first web 50'.
[0029] Although shown with two webs 50, 60 in FIGS. 1-3, and webs
50' and 60' in FIG. 4, the spiral belt 100, 100' may be formed from
more or fewer webs as needed to produce a spiral belt 100, 100'
having the desired properties for the particular application. In
FIG. 5, a third embodiment of a spiral belt 120, shown in a
cross-sectional view, is formed from an abrasive media 122
including three webs: a first web 125, a second web 130 and a third
web 135. In this embodiment, the second web 130 is somewhat
narrower than the first web 125 such that the second web 130 is
undercut from first web edges 126, 127 leaving a gap 131 adjacent
the seam 128 where the edges 126, 127 abut. The third web 135 is
then positioned within the gap 131, adjacent the first web 125 and
offset from one of the edges 126, 127 a portion 136, such that the
third web 135 overlaps and joins the seam 128 when the abrasive
media 122 is spirally wound into the belt 120. In some embodiments,
the second web 130 may be attached to the first web 125 using many
methods, including but not limited to adhesive. In some
embodiments, the third web 135 preferably includes adhesive at the
offset portion 136 (applied to either the first or third webs 125,
135 respectively) to join the seam 128 of the belt 120.
[0030] In some embodiments, preferred adhesives include phenolic
resins, aminoplast resins, hot melt resins, latex resins, epoxy
resins, ethylene acrylic acid resins, polyvinyl acetate resins,
radiation curable resins, urethane resins, polyester resins, and
pressure sensitive adhesives.
[0031] Adhesives in some embodiments are thermosetting resins. The
terms "thermosetting" or "thermoset" refer to reactive systems that
irreversibly cure upon application of heat and/or other energy
sources, such as E-beam, ultraviolet radiation, visible light,
etc., or with time upon the addition of a chemical catalyst,
moisture, or the like. The term "reactive" includes components that
react with each other (or self react) either by polymerizing, cross
linking, or both. The components are often referred to as resins.
The term "resin" refers to polydisperse systems containing
monomers, oligomers, polymers, or combinations thereof.
[0032] Phenolic resins may be used because of their thermal
properties, availability, cost and ease of handling. There are two
types of phenolic resins: resole and novolac. Resole phenolic
resins have a molar ratio of formaldehyde to phenol greater than or
equal to one to one, typically between 1.5:1.0 to 3.0:1.0. Novolac
resins have a molar ratio of formaldehyde to phenol less than one
to one.
[0033] In some embodiments, suitable phenolic resins include about
70% to about 85% solids, and in some embodiments preferably about
72% to about 82% solids. In some embodiments, the remainder of the
phenolic resin is preferably water with substantially no organic
solvent. If the percent solids is very low, more energy is required
to remove the water and/or solvent. If the percent solids is very
high, the viscosity of the resulting phenolic resin is too high,
which may lead to processing problems.
[0034] Examples of commercially available phenolic resins include
those available under the trade designations "VARCUM" and "DUREZ"
from Occidental Chemical Corp., Dallas, Tex.; "AROFENE" and
"AROTAP" from Ashland Chemical Company, Columbus, Ohio; "RESINOX"
from Monsanto, St. Louis, Mo.; and "BAKELITE" from Bakelite AG,
Iserlohn, Germany.
[0035] Modified phenolic resins may also be used. For example, a
plasticizer, latex resin, or reactive diluent may be added to a
phenolic resin to modify flexibility and/or hardness of the cured
phenolic binder.
[0036] A suitable aminoplast resin has at least one pendant
.alpha.,.beta.-unsaturated carbonyl group per molecule. These
unsaturated carbonyl groups may be acrylate, methacrylate or
acrylamide type groups. Examples of such materials include
N-hydroxymethyl-acrylamide; N,N'-oxydimethylenebisacrylamide; ortho
and para acrylamidomethylated phenol; acrylamidomethylated phenolic
novolac and combinations thereof.
[0037] Suitable epoxide resins include monomeric epoxy resins and
polymeric epoxy resins. These resins can vary greatly in the nature
of their backbones and substituent groups. Examples of epoxy resins
include 2,2-bis[4-(2,3-epoxypropoxyphenol)propane (diglycidyl ether
of bisphenol A)] and commercially available materials under the
trade designations "EPON 828," "EPON 1004," and "EPON 1001F,"
available from Shell Chemical Co., Houston, Tex.; and "DER-331,"
"DER-332," and "DER-334," all available from Dow Chemical Co.,
Midland, Mich. Other suitable epoxy resins include glycidyl ethers
of phenol formaldehyde novolac (e.g., "DEN-431" and "DEN-438"
available from Dow Chemical Co., Midland, Mich.). Other epoxy
resins include those described in U.S. Pat. No. 4,751,138 (Tumey,
et al.), incorporated herein by reference.
[0038] Other suitable adhesives include waterborne acrylic polymers
or copolymers, commercially available under the trade designation
"NEOCRYL;" urethane-acrylic copolymers, commercially available
under the trade designation "NEOPAC;" and polyurethane resins,
commercially available under the trade designation "NEOREZ," all
available from Neoresins, Inc., Wilmington, Mass.; and acrylic and
acrylonitrile latex resins, commercially available under the trade
designation "HYCAR," available from Noveon, Inc., Cleveland, Ohio.
Still other suitable adhesives include acrylated acrylic or
acrylated urethane polymer resins, commercially available under the
trade designation "NEORAD," available from Neoresins, Inc.,
Wilmington, Mass.; acrylated polyester resins, commercially
available from UCB Chemical Corp., Smyrna, Ga., and butadiene and
butadiene styrene resins.
[0039] Further suitable adhesives include a 100% solids blend of
vinyl ether monomers and oligomers. Such resins are typically low
molecular weight materials which form films by crosslinking upon
exposure to UV radiation. Examples of commercially available blends
include "RAPICURE" from ISP, Wayne, N.J.; and "VECTOMER" from
Reilly Industries, Greensboro, N.C. A catalyst is typically
required to initiate crosslinking. A suitable catalyst such as
UVI-6990 (a cationic photocatalyst) commercially available under
the trade designation "CYRACURE" from Dow Chemical, Midland, Mich.,
may be used.
[0040] Suitable urea-aldehyde resins include any urea derivatives
and any aldehydes which are capable of being rendered coatable and
have the capability of reacting together at an accelerated rate in
the presence of a catalyst, such as a cocatalyst.
[0041] Acrylate resins include both monomeric and polymeric
compounds that contain atoms of carbon, hydrogen and oxygen, and
optionally, nitrogen and halogens. Oxygen or nitrogen atoms or both
are generally present in ether, ester, urethane, amide, and urea
groups. Representative examples of acrylate resins include
methylacrylate, ethylacrylate, methyl methacrylate, ethyl
methacrylate, ethylene glycol diacrylate, ethylene glycol
dimethacrylate, hexanediol diacrylate, triethylene glycol
diacrylate, trimethylolpropane triacrylate, glycerol triacrlate,
pentaerythritol triacrylate, pentaerythritol trimethacrylate,
pentaerythritol tetraacrylate and pentaerythritol
tetramethacrylate.
[0042] A hot melt resin may also be used. Exemplary hot melt resins
are described in U.S. Pat. No. 5,436,063 (Follett, et al.),
incorporated herein by reference. Hot melt resins include
compositions that are solid at room temperature (about
20.degree.-22.degree. C.) but which, upon heating, melt to a
viscous liquid that can be readily applied to a backing. Useful hot
melt resins include thermoplastics such as polyolefins, polyesters,
nylons and acrylics, for example, a Zn-modified
ethylene/methacrylic acid copolymer available from E.I. DuPont
& Company of Wilmington, Del., under the tradename
"SURLYN."
[0043] Other hot melt resins may include blends of thermoplastic
resins with thermosetting resins. Thermoplastic resins are
typically supplied as pellets and must be melted, pumped and
extruded in hot form as a sheet or film. The film can be applied
directly to backings with non-contact equipment (drop or extrusion
dies, for example) or with contact equipment (ROC or rotating rod
dies). The extruded coating can be solidified by cooling or it can
be crosslinked with ultraviolet (UV) energy if radiation curable
components are present in the hot melt resin. It is also possible
to provide the hot melt resins as uncured, unsupported rolls of
adhesive film. In this instance, the resin is extruded, cast, or
coated to form the film. Such films are useful in transfer coating
the resin to a backing.
[0044] FIG. 6 is a partial cross-sectional view of a fourth
embodiment of a spiral belt 150 formed from a spiral wound abrasive
media 155 having three overlapped webs: an outermost web 160, a
middle web 170 and an innermost web 180. Each web 160, 170, 180 is
shown to be about equal in width 162, with each web 160, 170, 180
offset from the adjacent web or webs about one-half the width 162.
As a result, the middle web 170 has a one-half width exposed
portion 171 and the innermost web 180 has a one-half width exposed
portion 181. As the abrasive media 155 winds to form the spiral
belt 150, the first web 160 overlaps the exposed portion 171 of the
middle web 170, and the middle web 170 overlaps the exposed portion
181 of the innermost web 180, such that each web 160, 170, 180
produces abutting joints with no appreciable gap. Although four
embodiments have been shown and described, it is to be understood
that other web configurations for the abrasive media are possible
and within the contemplation and scope of the present invention. In
addition, although adhesive is described with reference to some
embodiments as preferred for attachment of the overlapped webs, it
is to be understood that other forms of attachment may also be used
and are within the scope of the present invention.
[0045] As shown, in some embodiments the abrasive media 80, 80',
122 and 155 are preferably configured as a plurality of webs
positioned in an adjacent and overlapping manner with respect to
each other. In some embodiments, the first or outermost webs 50,
50', 125, 160 are preferably coated abrasives formed from one or
more layers of material and one or more layers of abrasive
particles. Coated abrasives generally comprise a flexible backing
upon which a binder supports a coating of abrasive particles. The
abrasive particles are typically secured to the backing by a first
binder, commonly referred to as a make coat. Additionally, the
abrasive particles are generally oriented with their longest
dimension perpendicular to the backing to provide an optimum cut
rate. A second binder, commonly referred to as a size coat, is then
applied over the make coat and the abrasive particles to further
anchor the particles to the backing so as the reduce the likelihood
of abrasive particles fracturing off during use. In some
embodiments, a backing is preferably coated with iron seeded
sintered sol-gel alumina abrasive particles made according to U.S.
Pat. No. 5,611,829 (Monroe et al.), which is incorporated herein by
reference, in a phenol-formaldehyde binder and having a
phenol-formaldehyde size layer with calcium carbonate as a
filler.
[0046] Porous cloth, film, fabric and textile materials are
frequently used as backings for coated abrasive articles. The make
coat precursor is typically applied to the backing as a low
viscosity material. In this condition, the make coat precursor can
infiltrate into the interstices of the porous backing leaving an
insufficient coating thickness making it difficult to bond the
subsequently applied abrasive particles to the backing, and on
curing, resulting in the backing becoming stiff, hard and brittle.
As a result, it has become conventional to employ one or more
treatment coats, such as a presize, saturant coat, backsize or a
subsize coat, to seal the porous backing. Such treatment coats also
allow for the use of less expensive backing materials, such as
paper, combined with reinforcing materials, as described below to
achieve similar strength and tear resistance as that of more
expensive cloth type backings.
[0047] The presize, saturant coat, backsize and subsize coat
typically involve thermally curable resinous adhesives, such as
phenolic resins, epoxy resins, acrylate resins, acrylic lattices,
lattices, urethane resins, glue, starch and combinations thereof. A
saturant coat saturates the cloth and fills pores, resulting in a
less porous, stiffer cloth with more body. An increase in body
provides an increase in strength and durability of the article. A
presize coat, which is applied to the front side of the backing,
may add bulk to the cloth or may improve adhesion of subsequent
coatings, or may act as a barrier to excessive make coat
penetration. A backsize coat, which is applied to the back side of
the backing, i.e., the side opposite that to which the abrasive
grains are applied, adds body to the backing and protects the yarns
of the cloth from wear. A subsize coat is similar to a saturation
coat except that it is applied to a previously treated backing.
Paper backings may be treated to decrease or prevent penetration of
make adhesives and/or to waterproof.
[0048] As described above, a backing may be, for example, a
conventional, sealed coated abrasive backing or a porous,
non-sealed backing. Such a backing may be comprised of, for
example, cloth, vulcanized fiber, paper, nonwoven materials,
fibrous reinforced thermoplastic backing, polymeric films,
substrates containing hooked stems, looped fabrics, metal foils,
mesh foam backing, and laminated multilayer combinations thereof.
In some embodiments, the backing is preferably a polyester film
with a width of about 0.178 meter (7 inches) and a thickness of
about 0.00491 inch (125 micrometers). Cloth backings can be
untreated, saturated, presized, backsized, porous, or sealed, and
they may be woven or stitch bonded. The cloth backings may include
fibers or yarns of cotton, polyester, rayon, silk, nylon or blends
thereof. The cloth backing can be provided as laminates with
different backing materials described herein. Paper backings also
can be saturated, barrier coated, presized, backsized, untreated,
or fiber-reinforced. The paper backings also can be provided as
laminates with a different type of backing material. Nonwoven
backings include scrims and may be laminated to different backing
materials mentioned herein. The nonwovens may be formed of
cellulosic fibers, synthetic fibers or blends thereof. Polymeric
backings include polyolefin or polyester films, nylon, "SURLYN"
copolymer or other materials that may be hot-melt laminated. The
polymeric backings can be provided as blown film, or as laminates
of different types of polymeric materials, or laminates of
polymeric films with a non-polymeric type of backing material. The
backing can also be a stem web used alone or incorporating a
nonwoven, or as a laminate with a different type of backing. The
loop fabric backing can be brushed nylon, brushed polyester,
polyester stitched loop, and loop material laminated to a different
type of backing material. The foam backing may be a natural sponge
material or polyurethane foam and the like. The foam backing also
can be laminated to a different type of backing material. The mesh
backings can be made of polymeric or metal open-weave scrims.
Additionally, the backing may be a reinforced thermoplastic backing
that is disclosed in U.S. Pat. No. 5,417,725 (Stout, et al.).
[0049] An additional benefit of the processes and constructions
described in this invention is shape retention. After conventional
converting processes, coated abrasive belts and disks may change
shape or "cup" by as much as 2 inches (5 cm) depending upon the
environment of storage conditions for these products. These types
of changes are typically caused by the different web components in
such products picking up environmental moisture or humidity at
different rates. The present spiral process of this invention has
flexibility to allow the moisture sensitive web components
(typically paper) to be covered or protected from moist or humid
air. For example, in one embodiment of this invention, a polyester
film adhesive carrier also serves as a moisture barrier. The
prevention of cupping over a wide range of relative humidity
removes the necessity of further treating these types of products
in order to meet acceptability requirements.
[0050] In one embodiment, the first web 50 is preferably a coated
abrasive that may be formed from one or more layers of abrasive
particles and one or more layers of backing material. In this
embodiment, the second web 60 is preferably a splicing media formed
from one or more layers of film coated on at least one side with an
adhesive, such as an adhesive polymeric tape, or a coated fabric.
The adhesive may be a pressure sensitive adhesive (PSA) requiring
little or no processing after contact. Also, the adhesive may
require thermal or radiation curing to fully complete adhesion
between the webs 50, 60. The film may be a polymer film, such as a
0.0005 inch (12.7 micrometers) polyester film, or a fiber
reinforced film.
[0051] In a second embodiment, the first web 50 is also preferably
a coated abrasive. In this embodiment, the second web 60 is
preferably a reinforcing backing, as described above, that may be
attached to the first web 50 using, for example, a
pressure-sensitive adhesive (PSA). The area of adhesive on the
offset portion 66 may be applied to either the first or second webs
50, 60, respectively, after attachment of the second web 60 or may
be applied during such attachment.
[0052] In the third embodiment, the first web 125 is also
preferably a coated abrasive and the second web 130 is preferably a
reinforcing backing; the third web 135 is preferably a splicing
media, as described above for the first embodiment. Both the second
and third webs 130, 135 may be attached to the first web 125 using
one or more known techniques, with the adhesive on the offset
portion 136 applied during or after attachment of the webs 130,
135.
[0053] In the fourth embodiment, the outermost web 160 may also be
a coated abrasive, with the middle web 170 a reinforcing material
and the innermost web 180 a splicing media or other suitable
joining material. In one embodiment, the outermost web 160 may be
the topmost layer of a coated abrasive, such as an abrasive coated
backing material formed from a cloth or paper. However, the
outermost web 160 may also include multiple layers of abrasive
particles and/or multiple layers of backing material, if desired.
In one embodiment, the innermost web 180 may be the lowermost layer
of the coated abrasive, such as a reinforcing material, including a
nonwoven or other suitable material that provides strength to the
spiral belt 150 without providing a substantial increase in weight.
In some embodiments, the innermost web 180 may be a hook-and-loop
material, foam or other material described for use as a backing.
Optionally, the innermost web 180 may also be multiple layers if
desired.
[0054] In some embodiments, the middle web 170 is preferably an
adhesive layer that joins the other layers of the coated abrasive
forming the abrasive media 155. In one embodiment, the adhesive
layer is formed from adhesive material coated onto both major
surfaces of a film layer. For example, ethylene acrylic acid,
available, for example, under the trade designation "SCOTCHPACK"
from The 3M Company in St. Paul, Minn., is coated on both sides of
a 0.0005 inch (12.7 micrometers) polyester film to form a total
layer thickness of 0.0035 inch (88.9 micrometers). After the webs
160, 170, 180 are brought together, heat (at a temperature in the
range of about 260.degree.-270.degree. F. (127.degree.-132.degree.
C.) to achieve the cure temperature of the adhesive) and pressure
are applied to the overlapped portions to activate crosslinking and
bond the webs 160, 170, 180 together.
[0055] In another example, an ultraviolet (UV) curable resin is
coated onto both major surfaces of a polyester film layer to form
the middle web 170. One formulation of this resin includes 70 parts
"EPON 828" (epoxy), 30 parts "HYTREL 6356" (polyester thermoplastic
resin) commercially available from E.I. DuPont & Company and
1.5 parts "CYRACURE UVI-6974" (triarylsulfonium salt
photocatalyst). The mixture is heated to 125.degree.-130.degree. C.
before being applied to the film. In some embodiments, the adhesive
is then preferably tackified with UV energy by passing it once
beneath a 600 watt/inch (236 watt/cm) Fusion lamp using a D-bulb,
medium pressure, mercury vapor lamp as described by Fusion Systems,
Inc., Rockville, Md., just prior to winding of the spiral belt.
Once the middle adhesive layer is tackified, the spiral belt 150 is
formed from the three web layers 160, 170, 180. After belt
formation, the belt 150 is heated for five minutes at 125.degree.
C. to complete the adhesive cure.
[0056] In yet another embodiment, the middle web 170 may be formed
from an adhesive layer configured as a pre-cast film of adhesive
material. Such adhesives may include "SURLYN," a Zn-modified
ethylene/methacrylic acid copolymer by E.I. DuPont & Company of
Wilmington, Del.
[0057] In the first embodiment, the coated abrasive first web 50 is
formed in one or more processes, the second web 60 splicing media
is coated with adhesive and attached to the first web 50 along an
edge 52, 54 and then the combined abrasive media 80 is wound to
form the spiral belt 100. In a similar manner in the second and
third embodiment, the coated abrasive first web 50, 125 is formed
in one or more processes, the second reinforcing web 60, 130 is
formed in one or more processes, and then the second web 60, 130 is
attached to the first web 50, 125. In the second embodiment, the
combined abrasive media 80 is then spirally wound to form the belt
100. In the third embodiment, the third web 135 is formed in one or
more processes, an adhesive is applied, and the third web 135 is
attached to the first web 125. Afterward, the combined abrasive
media 122 is spirally wound to form the belt 120. In the fourth
embodiment, on the other hand, the formation of the abrasive media
155 preferably occurs simultaneously with the winding and formation
of the spiral belt 150, thereby eliminating numerous processing
steps, as well as the need for a splicing media, such as web 60 in
the first embodiment or web 135 in the third embodiment. Such
simultaneous formation also ensures both a good lamination of the
abrasive media 155 and a strongly joined belt 150.
[0058] Formation of the spiral belt 100, 100', 120, 150 from the
spiral wound abrasive media 80, 80', 122, 155 may be accomplished
in numerous ways. FIGS. 7 and 8 show one embodiment of a spiral
wound abrasive belt formation apparatus 200 configured to accept an
input abrasive media 210 formed from a first web 212 and a second
splicing web 214. The apparatus 200 includes a convexly curved hub
220 over which the abrasive media 210 is draped during the winding
process. The hub 220 is supported by the apparatus 200 in a
cantilevered manner to allow for continuous formation of a spiral
belt 215 of ever increasing width having a spiral seam 216 formed
where the edges of the first web 212 abut.
[0059] The apparatus 200 also includes a base 202 that supports the
hub 220 and a "C" shaped arm 230. The arm 230 extends out both
above and below a portion of the hub 220 and is mounted for pivotal
movement with respect to the base 202. At the furthermost upper end
231 of the arm 230 two upper press rollers 235, 236 are mounted for
pressure contact with two corresponding lower press rollers 237
that are mounted to furthermost lower end 232 of the arm 230. An
opening 222 formed in the hub 220 adjacent the press rollers 235,
236, 237 allows for contact between the upper press rollers 235,
236 and lower press rollers 237. As the abrasive media 210 passes
between the upper and lower press rollers 235, 236, 237, pressure
is applied to both the upper and lower surfaces of the seam 216.
Mounted on the underside 221 of the hub 220 adjacent the lower
press rollers 237 is an optional heating element 223 positioned to
radiate heat to the abrasive media 210. Optionally, a light source
(not shown) may also be mounted on the underside 221 of the hub 220
at the opening 222 to shine up through seam 216 and thus aid in
minimizing gaps at the seam.
[0060] One of the upper press rollers 235 is configured to be
manually driven by rotary mechanism 233. As the abrasive media 210
is fed into the apparatus 200, the rotary mechanism 233 is turned
to rotate the driven press roller 235 and thus pull the abrasive
media 210 through the apparatus. In this embodiment, the remainder
of the press rollers 236, 237 are not driven. Although configured
with a manual drive, it is to be understood that the apparatus 200
may also be configured with a powered drive, with or without
control.
[0061] The apparatus 200 also includes a guide tray 225. The guide
tray 225 is adjustably mounted to support the input abrasive media
210 at a desired height and angle with respect to the hub 220.
[0062] Prior to input into the apparatus 200, the abrasive media
210 is constructed from webs 212 and 214. An angled leading edge or
end 211 may be pre-cut into the abrasive media 210.
[0063] The apparatus 200 is then set up to form a spiral belt 215
having a desired width and circumference from pre-constructed
abrasive media 210. The angle of the guide tray 225 with respect to
the hub 220 establishes the angle at which the spiral belt 215 is
wound and, thus, the size of the belt 215. Therefore during set up,
the guide tray 225 is positioned at a desired angle with respect to
the hub 220. The press rollers 235, 236, 237 facilitate joining of
the first web 212 to the second web 214 by providing pressure to
the abrasive media 210 as the seam 216 is formed. Therefore, during
set up, the arm 230 is also pivoted to position the press rollers
235, 236, 237 at the desired angle to follow the abrasive media 210
as it is input from the guide tray 225. In addition, the pressure
exerted by the upper press rollers 235, 236 against the lower press
rollers 237 may be adjusted based on the requirements of the
abrasive media 210 forming the spiral belt 215, and heat to soften
or cure the adhesive may be supplied as needed from optional heater
223.
[0064] In operation, the abrasive media 210 is fed into the
apparatus 200 along the guide tray 225 and over the hub 220. The
leading end or edge 211 is wrapped around the hub 220 and is fed
back into the apparatus 200 at the press rollers 235, 236, 237 to
start formation of the seam 216 and, thus, the spiral belt 215. A
first operator feeds the abrasive media 210 into the apparatus 200
while monitoring and attempting to minimize any gap at the seam
216. A second operator manually drives the driven press roller 235
using the rotating mechanism 233, thereby continuously feeding the
abrasive media 210 into the apparatus and applying pressure at the
press rollers 235, 236, 237 to the first web 212 as it overlaps the
second web 214 at the seam 216 to bond the webs 212, 214 together.
Heat may also be provided by the optional heater 223, if available
and desired, to facilitate bonding of the webs 212, 214. The
abrasive media 210 continues to be fed into the apparatus 200 and
wrapped over the hub 220 forming the spiral belt 215 until a spiral
belt 215 of desired width has been formed or until a second end
(not shown) of the abrasive media 210 is reached. Once the spiral
belt 215 is completed, tabs (such as tabs 109 in FIG. 1) may be
applied to maintain adherence of the abrasive media 210 at both
ends.
[0065] FIG. 9 is a diagram of one embodiment of a spiral wound
abrasive belt winding apparatus 400 configured to accept a
plurality of webs, such as webs 412, 413, 414, that simultaneously
form an abrasive media 410 and a spiral belt 415. In some
embodiments, each web 412, 413 and 414 preferably has first and
second opposed major surfaces and elongated side edges. In some
embodiments, outermost web 412 is preferably a coated abrasive,
middle web 413 is preferably an adhesive layer, and innermost web
414 is preferably a reinforcing layer; however, other numbers and
types of webs may also be used. The three webs 412, 413, 414 are
wound over a stationary first hub 420 that is mounted in a
cantilevered manner. A moveably mounted second hub or mandrel 425
provides tension for the spiral belt 415 and adjusts to accommodate
spiral belts 415 of varying circumferences, as shown by phantom
second hub 426 and belt 416. Second hub 425 may also be mounted in
a cantilevered manner.
[0066] One advantage of the dual-hub system of the present
invention is that it is much easier to provide tension for spiral
belts 415 of varying circumferences by moving the second hub 425
relative to the first hub 420 than to change to the appropriately
sized mandrel for each desired spiral belt circumference. The
circumference of spiral belt 415 is infinitely adjustable to any
suitable length. In one embodiment, spiral belt 415 has a
circumference between about 10 inches (25.4 cm) and about 500
inches (1270 cm); more preferably, the circumference is between
about 20 inches (50.8 cm) and about 200 inches (508 cm); and most
preferably, the circumference is between about 103 inches (261.6
cm) and about 142 inches (360.7 cm). Another advantage of the
dual-hub system is that the second hub 425 can be moved closer to
the first hub 420 to release the tension and thereby facilitate
removal of the spiral belt 415 from the two hubs 420/425. This is
much easier than trying to remove a belt from a single mandrel
about which it is tightly wrapped. While two hubs 420/425 are
taught, with the first being stationary and the second being
movable, it is contemplated that more than two hubs may be used,
and any or all of them may be movable.
[0067] A web steering system including steering rollers 445a and
445b or other suitable devices may be included to control the
presentation of one or more of the webs. In some embodiments, the
webs 412, 413 and 414 are presented in a partially overlapping
fashion, such that during winding of the spiral belt 415, each
web's edges abut, preferably without appreciable gaps, forming
three relatively continuous layers (see the fourth spiral belt
embodiment in FIG. 6).
[0068] The splice angle of the spiral webs may be controlled by
selecting different widths of the input rolls of the abrasive web
or materials and/or different circumferences of the finished spiral
wound abrasive article in order to provide preferred non-marking
properties in some embodiments. For example, in a 52 inch (132.1
cm).times.103 inch (261.6 cm) belt, the typical splice or wrapping
angle (Angle 84 in FIG. 2) is about 71.degree. when the splice is
made with the use of conventional belt cutting devices and belt
presses. With the spiral belt process of the present invention, and
using a 12 inch (30.5 cm) wide input roll, the splice angle of the
spiral wrap would be about 6.7.degree.. Smaller splice angles are
preferred by customers where splice marking and loading are
generally the normal useful life endpoints of the abrasive
belt.
[0069] For example, for a 52 inch (132 cm).times.103 inch (262 cm)
belt, the splice angle may be adjusted from about 3.9.degree. to
about 20.5.degree. by varying the width of the input rolls from 7
inches (17.8 cm) to 36 inches (91.5 cm). As another example, using
an input web with a width of 7 inches (17.8 cm), a finished belt
with a circumferential length of 103 inches (262 cm) to 142 inches
(361 cm) may have a splice angle from about 2.8.degree. to about
3.9.degree.. In some embodiments of the present invention, the
splice or wrapping angle is preferably less than about 50.degree.,
more preferably less than about 30.degree., even more preferably
less than about 20.degree., and most preferably less than about
6.degree..
[0070] In the embodiment illustrated in FIG. 9, a pair of driven
nip rollers 430 drives the abrasive media 410 in a winding spiral
to form the spiral belt 415 and applies pressure to the abrasive
media 410 to assist adhesion between the webs 412, 413, 414. The
position and angle of the nip rollers 430 with respect to the
abrasive media 410 may be adjusted to accommodate changes in the
abrasive media 410 due to adjustment of the second hub 425,
adjustments of the input angle of the webs 412, 413, 414, or other
factors. In one embodiment, first hub 420, nip rollers 430, and
second hub 425 are preferably positioned so that the portion of
spiral belt 415 passing from first hub 420, past nip rollers 430,
and to second hub 425 is aligned substantially in a plane 432
(i.e., the outer edges of first hub 420 and second hub 425/426 are
aligned substantially in a plane 432 with nip rollers 430). In one
embodiment, these components are positioned so that plane 432 is
substantially vertical.
[0071] Optional heating element 423 may be positioned to radiate
heat to the abrasive media 410, thereby facilitating the bonding of
webs 412, 413, 414. FIG. 10 shows an alternate location for the
heating element 423, as compared to the location of heating element
223 shown in FIG. 8. In one embodiment, heating element 423
preferably comprises an infrared heater which heats both sides of
abrasive media 410. When heating element 423 is placed in this
position, it is advantageous for first hub 420, nip rollers 430,
and second hub 425 to be positioned so that the portion of spiral
belt 415 passing from first hub 420, past nip rollers 430, and to
second hub 425 is aligned substantially in plane 432, as discussed
above.
[0072] The process path includes plane 432 defined between first
hub 420 and second hub, 425/426. In one embodiment, one or both
hubs 420 and 425/426 are preferably movable. However, even when the
position of hub 420 and/or hub 425/426 is changed, the plane 432 is
maintained and does not change position. Accordingly, endless
abrasive media can be made having different media lengths
(circumferences) on the same equipment, by modifying the relative
positions of the hubs. The linear process path allows for better
control of the manufacturing process. For example, heating element
423 can remain stationary, and web 410 will pass by heating element
423 at a position relative to nip rollers 430 regardless of the
adjusted position of movably mounted second hub 425/426. Moreover,
the linear process path allows for better product control during
the manufacturing process.
[0073] Significant gaps or web overlap at the spiral seam (not
shown) of the spiral belt 415 will cause surface marks and other
surface non-conformities in an item ground or polished by the
spiral belt 415 in a subsequent operation. Therefore, minimization
of gaps or overlap is necessary to provide an acceptable spiral
belt 415. The apparatus 400 includes on embodiment of a gap
minimization system 440 to monitor the spiral seam and correct
unacceptable seam separation.
[0074] The gap minimization system 440 includes a sensing mechanism
444 that uses a light source 446 positioned on the back side of the
innermost web 414. The light source 446 may be visible light or may
be infrared light, if desired. A light sensor 447 is positioned at
the same point, but on the outside of outermost web 412. The light
sensor 447 senses the amount of light shining through a possible
gap at the seam of the outermost web 412. A controller 450 monitors
the light sensor 447 and controls a positioning system 451 that
adjusts the position of the outermost web 412 relative to the
spiral belt 415 to close the gap. The positioning system 451
includes a positioning motor 452 connected to the controller 450
and a web movement mechanism 453 driven by the positioning motor
452. In order to better accommodate changes in the position of the
outermost web 412, a steering roller 445b is included to route the
outermost web 412 through the web movement mechanism 453. With such
a gap minimization system 440, the light source 446 should be
strong enough to pass a small amount of light through an optimized
seam so that no light may be construed to be web overlap.
[0075] It is to be understood that other embodiments of a gap
minimization system are possible and are within the spirit and
scope of the present invention. For example, the visible light
source 446 and light sensor 447 may be switched such that the light
shines up through the abrasive media 410, thereby allowing an
operator to monitor the light passing through the seam, as well. In
addition, the web movement mechanism 453 may be only a push plate
that can move the web in one direction toward the spiral belt. In
this situation, the outermost web should be initially set up with a
small amount of gap to allow for such unidirectional
adjustment.
[0076] FIG. 10 is a diagram illustrating yet another embodiment of
a spiral wound abrasive forming apparatus and a method for forming
spiral wound abrasive article 415. FIG. 10 differs from FIG. 9 in
that only two webs 412 and 468 are combined to define the spiral
wound abrasive article 415. In some embodiments, each web 412 and
468 preferably has first and second opposed major surfaces and
elongated side edges. First winder 460 carries outermost web 412,
which in some embodiments is preferably of a coated abrasive
material. Second winder 462 carries prelaminated adhesive core web
466.
[0077] Prelaminated adhesive core web 466 includes composite
backing 468 and transfer tape 469. In some embodiments, a slip or
antifriction agent is preferably applied to composite backing 468
on a major surface opposite transfer tape 469, as described by U.S.
patent application Ser. No. 09/779,681 by Teetzel, entitled
"Composition Containing Graphite," commonly assigned with the
instant application to the 3M Innovative Properties Company and
incorporated herein by reference. Transfer tape 469 includes liner
470 which carries adhesive 471. Liner 470 is releasably attached to
adhesive layer 471 and is made from a material such as, for
example, paper or polyethylene coated with a silicone or
fluoropolymer resin. As prelaminated adhesive core web 466 is
unwound from winder 462, liner 470 of transfer tape 469 is removed,
leaving adhesive 471 on a major surface of composite backing 468.
Liner 470 is wound onto winder 464 for ease of disposal. The
combination of adhesive 471 and composite backing 468 defines an
adhesive composite web 472. In one embodiment, prelaminated
adhesive core web 466 is preferably about 0.178 meter (7 inches) in
width.
[0078] In some embodiments, adhesive composite web 472 is
preferably pulled toward first hub 420 for joining with outermost
web 412. Simultaneously, first web 412 was unwound from first
winder 460 and guided over first steering roller 445a, through web
controller 453, and over second steering roller 445b and, at an
offset of approximately 2 inches (5 cm), laminated to adhesive
composite web 472 at nip rollers 430 to form abrasive media 510
having a 2 inch (5 cm) seam of adhesive layer 471 exposed. Abrasive
media 510 are then successively wound around second hub 425 and
first hub 420 to form helical belt 415. In other respects, spiral
wound abrasive article 415 may be formed as described with respect
to FIG. 9, but only two webs (412 and 468), rather than three (412,
413, 414), are processed.
[0079] FIG. 11 is a partial cross-sectional view of a fifth
embodiment of abrasive media 510 formed from an abrasive media
including two webs, using for example, the method discussed with
reference to FIG. 10. Each turn of web 412 abuts the adjacent edge
474 of web 412 with no appreciable gap. The seam between web edges
474 is adhered together by overlap of adhesive composite web 472.
In some embodiments, adhesive 471 preferably covers an entire major
surface of composite backing 468, such that edges 478 of composite
backing web 468 are co-linear with edges 480 of adhesive 471,
thereby forming an edge 476 of adhesive composite web 472. In one
embodiment, web 412 and adhesive composite web 472 have the same
width, the overlap 482 between web 412 and adhesive composite web
472 is between about 1/4 and about 1/2 of the width of each web,
and each turn of adhesive composite web 472 abuts the adjacent edge
476 of adhesive composite web 472 with no appreciable gap.
[0080] In one embodiment, prelaminated adhesive composite web 472
is formed by applying transfer tape 469 (shown in FIG. 12), to
composite backing web 468. Transfer tape 469 includes adhesive 471
and liner 470 and can be, for example, a transfer tape such as a
tape commercially available from the 3M Company under the trade
designation "467MP." Liner 470 is removed in the process described
with reference to FIG. 10, leaving adhesive 471 on composite
backing web 468, resulting in adhesive composite web 472 which is
then adhered to outermost web 412. In one embodiment, adhesive 471
comprises a film coated with adhesive on both sides. One side of
adhesive film 471 is prelaminated to composite backing web 468 and
the other side of adhesive film 471 adheres to liner 470, which is
removed in the process described above, resulting in adhesive
composite web 472 which is then adhered to outermost web 412.
[0081] In one embodiment, outermost web 412 preferably comprises a
coated abrasive including a backing layer of paper, textile, or
polymeric material; a binder of thermally curable resinous
adhesives, such as phenolic resins, epoxy resins, acrylate resins,
acrylic lattices, lattices, urethane resins, glue, starch and
combinations thereof; and abrasive particles of flint, garnet,
aluminum oxide, alumina zirconia, ceramic aluminum oxide, diamond,
silicon carbide, seeded or unseeded sol-gel alumina and the like.
In some embodiments, a backing of polyester film is preferably
coated with iron seeded sintered sol-gel alumina abrasive particles
in a phenol-formaldehyde binder and having a phenol-formaldehyde
size layer with calcium carbonate as a filler.
[0082] In some embodiments, adhesive composite web 472 preferably
comprises backing material 468 of paper, textile, or polymeric
material; coated or otherwise provided with a layer of adhesive 471
such as a phenolic resin, aminoplast resin, hot melt resin, latex
resin, epoxy resin, ethylene acrylic acid resin, polyvinyl acetate
resin, radiation curable resin, urea-aldehyde resin, urethane
resin, polyurethane resin, acrylate resin, butadiene or butadiene
styrene resin, acrylic polymer or copolymer, urethane-acrylic
copolymer, vinyl either monomer and oligomer, or pressure sensitive
adhesive. In one embodiment, composite backing 468 is preferably
formed from 250 gram/m.sup.2 cylinder paper and 28 gram/m.sup.2
non-woven polyester laminated together with "SURLYN" copolymer
adhesive. In one embodiment, adhesive transfer tape 469 is
preferably obtained from the 3M Company under the trade designation
"467MP." In one embodiment, adhesive transfer tape 469 is
preferably laminated to the paper side of composite backing 468 and
a graphite slip coating is preferably applied to the nonwoven side
of composite backing 468.
[0083] FIG. 12 is a diagram illustrating yet another embodiment of
a spiral wound abrasive forming apparatus. FIG. 12 differs from
FIG. 10 in that second hub 425 may remain stationary, and the
position of a movably mounted third hub or mandrel 435 may instead
be changed to vary the length of the process path and, as a result,
the length of the circumference of the spiral belt 415 (see, e.g.,
longer phantom spiral belt 416). In one embodiment, third hub 435
is preferably movable to different positions along direction 438,
between, for example, the positions illustrated for third hub 435
and phantom third hub 436. While movement of third hub 435 allows
changes in the circumference of the spiral belt being formed, the
linear portion 432 of the process path is unaffected.
[0084] In some embodiments, the abrasive web may, for example, be
formed by applying a slurry of abrasive particles in a binder
precursor that is subsequently cured to form the binder. Such
slurries of abrasive particles in a binder precursor and techniques
for applying them are well known in the abrasive art. In some
embodiments, the abrasive media may, for example, be applied to the
outer major surface of the spiral wound belt.
[0085] The present invention provides a spiral wound abrasive belt
that may be formed in a continuous manner, may be formed in varying
circumferences, and may be slit to a large range of widths, as
needed. The spiral belt may be constructed from abrasive media
whose edges are joined together along a spiral seam, or may be
constructed from individual webs that simultaneously form the
abrasive media and the spiral belt. The webs used to construct the
spiral belt may be chosen to optimize the strength and durability
of the belt, thus producing abrasive belts with significantly
longer lives, while minimizing the weight and other belt
characteristics that impact installation and use of the belt in
subsequent abrasive applications.
[0086] The method of forming spiral wound abrasive belts and the
apparatuses for practicing these methods in accordance with the
present invention result in reduced labor and material costs. The
methods and machines eliminate the need for multiple splices and
custom sized equipment to form belts having the necessary
circumference and width for a specific application. In addition,
the offset layer process and equipment eliminate the need for
additional joining material and allow for the inclusion of all
layers of the abrasive media into the spiral belt construction.
[0087] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
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