Note: Descriptions are shown in the official language in which they were submitted.
CA 02170722 2001-09-12
METHOD AND APPARATUS FOR MAKING A PAINT ROLLER
BACKGROUND OF THE L'VVENTION
1. Field of the Invention
This invention pertains to a method and apparatus for making paint rollers of
the
type used for applying paint to walls and the like.
2. Prior Art
Paint rollers are widely used by professionals and amateurs for applying paint
to
walls, ceilings, and other surfaces. Typically the roller is used with an
applicator having a
handle terminating in a rotatable member to which the roller is secured. The
roller itself
14 comprises two main components, a core and a paint absorbing cover. The core
is typically
paper or plastic, while the cover may be wool, polyester, etc. Generally
speaking, the methods
used for forming the core and for securing the cover to the core determine
whether the roller
is reusable, as paint solvents such as turpentine, mineral spirits, etc. are
also solvents for many
adhesives.
1~ To speed production and reduce costs, paint rollers are manufactured using
an
automated assembly line. For example, according to one known technique, a
disposable roller
is made by tirst feeding three chipboard paper strips at an angle to a mandril
for overlapping,
helical winding to form an endless, belt driven core. The paper strips are
supplied in rolls for
mounting on spindles for continuous feeding, and a continuous adhesive stream
is applied to the
0 outer surfaces of the strips as they feed uff the rollers such that the
strips adhere together as they
are helicallv wound to form the core. Because the roller is intended as a
throwaway, the
adhesive is not critical, and an inexpensive adhesive, such as a ~,vater
soluble white flue, is used.
CA 02170722 2001-09-12
As the endless core is belt driven down the line, it reaches a second adhesive
applicator where
a continuous adhesive stream is applied to the outer surface of the core after
which a continuous
strip of the cover material, such as polyester, is helically wound on to the
core where it is
secured by the adhesive. All that remains is to cut the resulting endless
roller down to usable
sizes, which is usually accomplished in two steps, first using a fly away
cutter to cut, e.g., 54
inch stock, and then using a recutter to cut the stock into lengths of, e.g.,
seven or nine inches.
The rollers thus formed may not be reused, as the adhesive which binds the
core and secures
the cover to the core is soluble in paint solvents, and consequently any
attempt to clean the roller
leads to unravelling of the core and separation of the core from the cover.
p If reusable rollers are desired, phenolic impregnated paper strips are
substituted
for the chipboard strips in the process described above, and a thermosetting
glue is used for
securing the core. Thereafter, the core is heated in a mufti-stage infrared
heater, after which
a hot melt glue is applied to the core's outer surface. The rollers are then
completed as before,
i.e., by helically winding the fabric cover on to the core and then cutting
the resulting endless
roller into usable lengths. The obvious drawback of reusable cores formed in
this manner is that
they require a longer assembly line, due to the need of a heater, and because
the phenolic must
be heated to a predetermined temperature, there is an obvious trade off
between the number of
heater stages and the speed of the line. l~foreover, while the resulting
rollers are termed
reusable because they do not separate when placed in paint solvents, prolonged
exposure to such
_'0 solvents, e.~., about two days, does result in separation.
.W other reusable roller is disclosed in U.S. Pat. ~lo. 4,692,975 issued to
Garcia.
Rather than usir'7 helically ~.vound strips to form the core, the Garcia
roller is formed using a
CA 02170722 2001-09-12
core comprised of preformed thermoplastic (e.g. polypropylene) tubular stock.
With the core
mounted on a rotating spindle, a movable carriage mounted at an angle to the
spindle feeds a
continuous strip of fabric, the carriage moving parallel to the spindle in
timed relation to its
rotation so that the fabric strip is wound on the plastic core in a tight
helix. Also mounted to
the movable carriage is a heat source for heat-softening the thermoplastic
core just in advance
of the point where the fabric strip is applied, such that the fabric is bonded
to the core as it is
wound thereon. One advantage of the roller disclosed in the Garcia patent is
that it is reusable,
as the bond formed between cover and core is a strong one not subject to
separation from
exposure to paint solvents. Another advantage is that the manufacturing
process does not require
the application of an adhesive to bond the cover to the core. There are,
however, drawbacks.
For one, while prior art techniques use rolls of, e.g., chipboard or paper,
the Garcia process
requires preformed thermoplastic tubular cores which are considerably bulkier
than rolls, more
expensive to transport, and more difficult to handle. Another drawback is the
anticipated speed
limit of the Garcia process dictated by the necessity that the heater, which
advances along the
core just in front of the fabric strip, move slow enough to insure softening
of the thermoplastic
core, in the absence of which the fabric cover will not bond.
_>
CA 02170722 2001-09-12
SIJMI~IARY OF THE INVENTION
In accordance with a first embodiment of the present invention, paint rollers
are
formed from one or more strips of thermoplastic material, preferably
polypropylene, wound
together in overlapping relation about a stationary mandril to form a core, to
which a cover is
applied. The thermoplastic strips comprising the core are bonded together by a
thermoplastic
material, again preferably polypropylene, which is applied to the strips in
liquid form, as by
sufficiently heating the polypropylene in a demand melter to liquefy it, and
then feeding it to the
strips via feed tubes extending from the melter. The thermoplastic strips are
rapidly bonded to
each other to form the core as the liquid polypropylene cools and sets. After
the core is formed,
an adhesive, preferably additional liquid polypropylene, is applied to the
outer surface of the
core whereupon a fabric cover, comprised for example of polyester, is wound
about the core and
bonded thereto as the liquid polypropylene cools and sets. The resulting
roller is reusable owing
to the strength of the polypropylene bonding, which resists separation upon
immersion in paint
solvents, even with exposure over several days.
In accordance with a second embodiment of the present invention, liquefied
thermoplastic is applied to a belt which transfers the rapid setting liquefied
thermoplastic to the
stationary mandril. Since the liquefied thermoplastic does not stick to the
metal surface of the
mandril, a coating forms about the mandril. This thermoplastic coating sets to
form the core.
In accordance with yet another embodiment of the present invention, the paint
?0 rollers are formed in a manner similar to that of the first embodiment
except that the step of
preforming the core by applying adhesive to the heiically wound thermoplastic
strip or strips is
eliminated. ~ccerdin~ to this embcdiment, the paint roller is made by
helically winding a
=I
CA 02170722 2001-09-12
thermoplastic strip around a mandriI, applying a layer of liquified adhesive
onto the outer surface
of the wound strip and then helically wrapping a fabric cover about the wound
strip to thereby
form a paint roller. In comparison with the first embodiment, this embodiment
is more~efficient
and less costly as it requires only a single application of liquid adhesive.
In another embodiment, the driven belt is located at a point after the fabric
cover
strip has been applied onto the wound strip but before the endless roller is
cut into usable
lengths. The driven belt is so positioned along the mandril and the
temperature of the liquid
thermoplastic adhesive being applied is such that the adhesive has not yet
fully set by the time
that the driven belt wraps the formed roller. The driven belt aids in pressing
the fabric cover
:0 strip onto the thermoplastic adhesive being applied onto the core so as to
form a tight and secure
bond between the fabric cover and the core. The driven belt also further
tightens the wrapping
the wound strip forming the core.
In addition, in any of the above-described embodiments, the mandril can be
cooled. Such cooling of the mandril accelerates the thermosetting of the
thermoplastic material
comprising the core or the adhesive used to bond the cover to the care and
allows the
manufacturing process to be sped up, thereby increasing production, and~or
allows the
production line to occupy less linear space (i.e., the mandril may be
shortened), since the length
01 tre mandril is, to an extent, dictated by the amount of time it takes for
the thermoplastic
material to set before the roller is cut into usable lengths.
The rollers of the present invention are preferably forr-:ed using an
asserrbIy Iine
process. w~i:cn a simplit:e'd by the fact that :he process fcr ma::ir,~ ~l-.e
paint rollers et the
n~,e.~.t:c;~ uses many c:,r;:poner.ts ccrru~nen :o prior art systems er
mahi:~g paint tellers
CA 02170722 2001-09-12
Furthermore, when an assembly line process is used, it is expected to be quite
fast, as the
polypropylene may be liquified at a location remote from the assembly line,
whereby the process
need not be slowed to accommodate on-line heating. Furthermore, because of the
rapidity with
which liquid polypropylene sets under ambient conditions, it is anticipated
that the endless roller
formed on the assembly line may be cut almost immediately after the fabric
cover is applied,
thereby allowing the assembly line to be kept quite short while still yielding
a strongly bonded,
reusable roller.
Other objects and features of the present invention will become apparent from
the
following detailed description considered in conjunction with the accompanying
drawings. It is
to be understood, however, that the drawings are intended solely for purposes
of illustration and
not as a definition of the limits of the invention, for which reference should
be made to the
appended claims.
6
CA 02170722 2001-09-12
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, wherein like reference numerals delineate similar elements
throughout the several views:
FIG. 1 is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with a first embodiment of the present invention;
FIG. 2 is a perspective view of a roller made in accordance with the present
invention;
FIG. 3 is a sectional view taken substantially along line 3-3 in FIG. 2;
FIG. :I is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with a second embodiment of the present invention;
FIG. 5 is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with a third embodiment of the present invention;
FIG. 6 is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with a fourth embodiment of the present invention;
FIG. 7 is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with yet another embodiment of the present invention;
and
FIG. 8 is a diagrammatic representation of an apparatus suitable for making
rollers in accordance with yet another embodiment of the present invention.
7
CA 02170722 2001-09-12
DETAILED DESCRIPTION OF THE PREFERRED EMBODIII~iENTS
Referring now to the drawings, and initially to FIG. 1, an apparatus suitable
for
making rollers in accordance with a first embodiment of the present invention
is generally
designated as 10. One advantage of the apparatus 10 is that it incorporates
several components
common to widely used prior art systems, and hence is easily retrofitted.
These components
include a housing 12 supporting a stationary mandril 14, a driven belt 16
wound about the
formed core 18 for advancing it to the right in FIG. 1, a flyaway cutter 20
for cutting the
formed endless roller 22 into usable lengths, and journaled spindles (not
shown) for supporting
the three rolls (also not shown) from which the strips 24, 26, 28 and 30 are
drawn. Components
0 not found in prior art systems are a demand heater 32 for maintaining a
liquid supply of
thermoplastic material, preferably liquid polypropylene 34, applicators 36, 38
and 40 connected
by, respectively, feed tubes 42, 44 and 46 to heater 32 for applying the
liquid polypropylene at
predetermined points in the process, and the use of thermoplastic strips 24,
26 and 28, again
preferably polypropylene, to form the core I8.
An advantage of the invention is that it employs rolls of polypropylene strips
which are easy to handle and readily substituted for the rolls of chipboard
and paper strips
common in prior art processes. As diagrammatically illustrated in FIG. 1, and
in accordance
with known techniques, three polypropylene strips 24, 26 and 28 are fed at an
angle to the
mandril 14, two from one side and one from the other. To start the process,
and as is also
_~J known in the art, the free ends of the strips ?-1, 26 and ''8, which are
typically ? 1li 16", 2 3I-~"
and ? 13i 16" wide, are manually wound about ;he mandril 14 until they extend
beyond the belt
16, at which point the belt is tiehtly wrapped about the strips and driven by
activating driven
8
CA 02170722 2001-09-12
wheel 48, whereupon the belt advances the formed core I8 to the right in FIG.
1, thereby
continuously pulling fresh lengths of the polypropylene strips 24, 26 and 28
onto the stationary
mandril 14. As shown, the strip 24 is fed over the mandril 14, and the strips
26, 28 are fed
under the mandril such that all three strips are advanced to the right in FIG.
1 by the rotation
of the belt 16, and preferably the strips 24, 26 and 28 are wound in tight
helical paths.
Still referring to FIG. 1, the applicators 36, 38 apply liquid polypropylene
from
the demand melter 32 to the outer surfaces of the strips 26, 28 just before
they are wound on
the mandril 14. The demand melter is set to maintain its interior at a
temperature sufficiently
high to insure that the polypropylene therein is in liquid form. As the strips
24, 26 and 28 are
0 wound onto the mandril in overlapping fashion by the advancing action of the
belt 16, the liquid
polypropylene is disposed between the overlapping strips, and because the
strips are also
comprised of polypropylene, the overlapping strips are rapidly bonded to each
other as the liquid
polypropylene cools and sets, thereby forming an integral endless core 18.
Next, additional liquid polypropylene is applied onto the outer surface of the
core
18 by the applicator 40 which is situated just to the right of the belt 16 in
FIG. 1. Immediately
thereafter, the fabric cover 30, which may comprise any of the conventional
materials now in
use, such as polyester, is wound onto the core 18, whereupon it is rapidly
bonded to the core
18 as liquid polypropylene cools and sets. Again, because the core is also
formed of
polypropylene, the strong bond is formed between the core 18 and the fabric
cover 30. It will
=0 be appreciated that in accordance with !chown techniques, winding of the
fabric cover 30 onto
the core i8 is started manually, just like the Strips ?4, 26 and 28, and that
fresh lengths of the
tabric strip 0 are then continuously pulled onto the core 13 by the
advancement of the core 18
c~
CA 02170722 2001-09-12
to the right as effected by the belt 16. Again, the cover strip 30 is
preferably wound in a tight
helical path about the core.
At this point, all that remains is to cut the now formed endless roller 22
into
usable lengths. Because the polypropylene bonds which secure the core 18 and
hold the fabric
cover 30 to the core set rapidly with the cooling of the liquid polypropylene,
it is anticipated that
the flyaway cutter for cutting the endless roller 22 may be positioned quite
close to the ontake
of the fabric cover 30. The actual position of the flyaway cutter 20 can, of
course, be adjusted
as necessary to insure that the cutting operation is not effected before the
bonds set. As is
common, the flyaway cutter may be adjusted to cut the endless roller 22 into
64" stock, which
may then be recut to the usual 7" and 9" sizes.
A finished roller 50 in accordance with the invention is shown in FIG. 2, and
in
cross-section in FIG. 3. The roller 50 may be used in the same manner as prior
art rollers,
namely, as a replacement element or, with the addition of end pieces 52 and a
handle 54, as part
of a complete roller assembly. In FIG. 3, 56 represents the polypropylene bond
joining the
fabric cover 30 to the core 18. Because polypropylene bonds are not soluble in
paint solvents,
the rollers 50 produced in accordance with the invention are reusable. Indeed,
because the core
18 itself comprises polypropylene, the roller 50 defines a substantially
integral assembly, and
it is expected that separation of the fabric 30 from the core 18 will not
occur even if the roller
is exposed to a paint solvent over a period of several days.
=0 Referring now to FIG. 4, a second embodiment of an apparatus in accordance
with the present invention is generally designated at 60. As shown, strips
2~l., 26 and 28, teed
tubes ~''. -1-~ and applicators ~6, 38 of the apparatus IO of FIG. 1 have all
been eliminated from
CA 02170722 2001-09-12
apparatus 60. A feed tube 62 and an applicator 64 feed liquefied polypropylene
34 from heater
tank 32 for application to driven belt 16. The driven belt 16 is formed of a
material such as
rubber or teflon compound to which liquid polypropylene 34 does not adhere.
Driven belt 16
is tightly wrapped around mandril 14 such that the liquid polypropylene 34
applied to belt 16
is transferred to mandril 14 by driven belt 16. Mandril 14 is preferably
composed of a suitable
metal. When transferred to mandril 14 the liquid polypropylene 34 forms a
coating thereabout,
but does not adhere to the stationary mandril, which is formed of metal. The
coating is applied
evenly about the mandril as the belt 16 rotates thereabout. The coating sets
rapidly to form a
core 18 which is then continuously advanced to the right by the rotational
motion of the belt 16.
Applicator 40, located preferably 12-18 inches from driven belt 16, applies
liquid polypropylene
to core 18 in the same manner and for the same purpose as in the apparatus 10
of FIG. l:
Apart from the advantage of producing extremely well bonded, reusable rollers,
the present invention provides several manufacturing advantages. For one,
because of the
rapidity with which the polypropylene bonds set, the assembly line can be kept
quite short, with
the flyaway cutter, the final component on the line, positioned close to the
ontake of fabric strip
30. Also, because the polypropylene is preheated to a liquid state in the
heater 32, which may
be remotely located, there is no need for a heating element in proximity to
the assembly line,
and consequently the line need not be slowed to accommodate on-line heating.
Therefore, it is
anticipated that the line can be run quite fast, thereby increasing production
and reducing unit
~0 cost. Another advantage, noted above, is that the method of the invention
forms the core and
cover from strips, just like the prior art methods, and therefore is easily
retrotitted to existing
systems usin~, several of their components which, of course, is less expensive
than a ne~.v
11
CA 02170722 2001-09-12
installation. Also, as compared with those prior art systems which utilize
prefabricated tubular
stock for the roller core, the present invention's reliance on polypropylene
strips is superior, as
strips, which come in rolls, are less bulky and easier to handle. Their lesser
bulk also reduces
transportation costs.
As shown in FIGS. 5 and 6, in place of fabric cover 30, a flocking head 65 may
be used to apply a suitable cover material, such as blown-on fibers, to core
18.
With reference now to FIG. 7, and in accordance with yet another embodiment
of the present invention, the step of applying adhesive to the strip or strips
24 prior to the step
of winding the strip 24 about the mandril 14 is eliminated. Rather, the
adhesive is applied only
after the strip 24 is wound on the mandril 14 and before the step of wrapping
the fabric cover
strip 30 onto the wound strip 24.
In accordance with the embodiment of FIG. 7, preferably a single strip 24 is
helically wound about the stationary mandril 14. The wound strip 24 is then
advanced along the
longitudinal axis of the mandril 14 by the traction force applied by the belt
16. Preferably, the
l~ strip 24 is helically wound or wrapped about the mandril 14 with successive
turns in a closely-
spaced manner, though it is also contemplated that adjacent edges may be
abutting or
overlapping. Preferably, the strip 24 is made of a thermoplastic material such
as, for example,
polypropylene.
The wound strip 24 is advanced along the longitudinal axis of the mandril 14
to
~0 a position, preferably downstream from the driven belt 16, where a fabric
cover strip 30 is
applied. Prior to the application of the fabric cover strip 30, the applicator
.~0 applies a layer
12
CA 02170722 2001-09-12
of adhesive such as, for example, a liquid thermoplastic material, to the
outer surface of the
wound strip 24. The liquid thermoplastic material is preferably polypropylene.
The roller 22 is then formed by helically winding or wrapping the fabric strip
30
over the adhesive layer and about the outer surface of the wound strip 24 with
sufficient tensile
force so that the fabric cover 30 lays smoothly over the adhesive layer.
Preferably, the adhesive
layer is of uniform thickness.
After the adhesive or liquid polypropylene cools and sets, which is extremely
fast
in the case of liquid polypropylene, the roller 22 may be cut into desirable
lengths by a cutting
device such as, for example, a flyaway cutter disposed proximate thereto. The
paint roller ~0
formed in accordance with this embodiment is an integral roller having the
same advantageous
characteristics attributable to rollers manufactured according to the other
embodiments described
herein.
Therefore, in accordance with the embodiment of FIG. 7, the entire roller 22
is
formed in a single step as the fabric cover 30 is wrapped about the wound
strip 24. That is,
there is no need to provide a formed core and then wrap the fabric about the
formed core.
Rather, the entire roller 22 including the core is fabricated in a single step
as the fabric is wound
about the adhesiveIy coated wound strip 24.
In a particular example of construction in accordance with the embodiment of
FIG. 7, the roller 22 comprises a wound polypropylene strip ?4 having a
thickness in the range
~0 of about 0.00 inch to 0.030 inch; an adhesive layer of polypropylene having
a thickness in the
range of about 0.005 inch to 0.010 inch; and a fabric cover JO made of
polyester having any
suitable thickness.
13
CA 02170722 2001-09-12
Advantageously, the apparatus according to this embodiment requires only one
applicator 40 and one feed tube 46. Therefore, feed tubes 42, 44 and
applicators 36 and 38 used
in the embodiment of FIG. 1 are eliminated.
The embodiment of the present invention shown in FIG. 8, is substantially the
same as that shown in FIG. 7 except that the driven belt 16 is located at a
point after the fabric
cover strip 30 has been applied onto the wound strip 24 but before the flyaway
cutter 20 cuts
the formed endless roller 22 into usable lengths. The driven belt 16 is so
positioned along the
mandril 14 and the temperature of the liquid thermoplastic adhesive,
preferably polypropylene,
being applied by the applicator 40 is such that the adhesive has not yet fully
set by the time that
the driven belt I6 wraps the formed roller 22. The driven belt 16 is thus used
not only to
advance the roller 22 (and thus also the wound strip 24) along the mandril 14
as it is being
formed but also to press the fabric cover strip 30 onto the thermoplastic
adhesive being applied
by the applicator 40 onto the core 18 so as to form a tight and secure bond
between the fabric
cover 30 and the core 18. Additionally, the driven belt 16 also further
tightens the wrapping
of the wound strip 24 forming the core. Advantageously, the apparatus
according to this
embodiment requires only one applicator 40 and one feed tube 46.
In a roller made in accordance with the embodiment of the present invention
shown in FIG. 8, the wound strip 24 was made of polypropylene having a
thickness of about
0.020 inch to 0.040 inch, and an adhesive layer of polypropylene having a
thickness of about
?0 0.00 inch to 0.010 inch. The fabric cover 30 was made of polyester.
In accordance with this embodiment of the present invention, the driven belt
16
in the embodiments shown in FIGS. 1, ~ and 6 rnay be Similarly positioned
alon; the mandril
1:1
CA 02170722 2001-09-12
14 at a point after the fabric cover strip 30 has been applied onto the wound
strip 24 but before
the flyaway cutter 20 cuts the formed endless roller 22 into usable lengths.
In still another embodiment of the present invention, the adhesive applicator
shown in FIG. 8 may be replaced by a heating means, such as a flame heater,
infrared light
heater and/or microwave generator, which heats and softens the wound strip 24
which is
preferably comprised of thermoplastic material, such as polypropylene. The
fabric cover strip
30 is then applied to the core I8, or alternatively the fibers are blown onto
the core by the
flocking head 65. The fabric cover is then pressed onto the core 18 by the
driven belt 16.
Alternatively, the adhesive applicator is eliminated, and the endless roller
22 is heated after the
cover has been applied thereto; the cover is then pressed onto the core by the
driven belt 16.
Alternatively, the adhesive is applied to the core and the core is heated
before the
cover is applied thereto and before the cover is pressed onto the core by the
driven belt 16.
Although a driven belt 16 has been shown and described in conjunction with the
embodiment shown in FIG. 8, other means of pressing the cover onto the core to
form a bond
therebetween may be used, for example, the endless roller can alternatively
pass through a
segment of rigid tubing or circumferential rollers, the diameter of which
gradually decreases in
the direction of flow of the tubing until the desired pressing force is
obtained.
Additionally, in all of the described embodiments, the mandril may also be
refrigerated or cooled so as to decrease the setting time of the thermoplastic
material. Such
_'0 cooling of the mandril can occur at a point upstream of the point that the
core is formed on the
mandril or else~,vhere downstream along the mandril up to the point that the
thermoplastic
material gets. Cooling may be accomplished by any means such as by blowing
cooled air onto
CA 02170722 2001-09-12
the mandril or through its central axis, by placing cooling coils adjacent or
in contact with the
mandril either on the outer circumference of the mandril or within its central
axis, or by having
the mandril directly contact a cooling fluid, either within its central axis
or on its outer surface.
Thus, while there have been shown and described and pointed out fundamental
novel features of the invention as applied to a preferred embodiment thereof,
it will be
understood that various omissions and substitutions and changes in the form
and details of the
devices illustrated, and in their operation, may be made by those skilled in
the art without
departing from the spirit of the invention. For example, it is expressly
intended that all
combinations of those elements and/or method steps which perform substantially
the same
function in substantially the same way to achieve the same results are within
the scope of the
invention. Substitutions of elements from one described embodiment to another
are also fully
intended and contemplated. It is also to be understood that the drawings are
not necessarily
drawn to scale but that they are merely conceptual in nature. It is the
intention, therefore, to
be limited only as indicated by the scope of the claims appended hereto.
16
