Note: Descriptions are shown in the official language in which they were submitted.
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77009 PATENT APPLICATION
METHOD OF MAHING A PAINT ROLLER WITH NON-PLASTIC BASE MATERIAL
BACKGROUND OF THE INVENTION
The present invention relates generally to a method and apparatus for
manufacturing
reusable paint rollers.
Paint rollers are frequently used by professional painters and non-
professional painters to
apply a layer of paint to walls, ceilings, and other surfaces. Paint rollers
increase the painter's
efficiency by permitting the paint to be applied much more rapidly than is
possible by using a
conventional paint brush.
Paint rollers typically include a core and a paint absorbing outer fabric
layer or cover. The
core may be solid preformed stock material, or may be wound from one or more
strips of base
material. An example of a known paint roller is disclosed in U.S. Patent No.
4,692,975 issued to
Garcia. Garcia uses a core comprised of a preformed tube of solid
thermoplastic material. A
moveable platform applies a continuous strip of fabric to the rotating core.
The core is partially
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melted just prior to application of the fabric material such that the fabric
becomes permanently
bonded to the core. However, this technique is expensive, as preformed stock
material is required.
Another example of a known paint roller is disclosed in U.S. Patent No.
5,572,790 issued
to Sekar. Sekar discloses using multiple strips of thermoplastic material,
which are wound about a
stationary mandril to form a core. Once the core is formed, additional liquid
thermoplastic
material is applied to the core to act as an adhesive to bond the fabric
material to the core, which
is then also wound about the core. However, Sekar has several disadvantages.
Liquid
thermoplastic material must be applied to the core from one or more feed
nozzles, or other type
of device capable of accurately applying the liquid "adhesive." It is
difficult to accurately regulate
the application of liquid thermoplastic material from the application nozzle
to the rotating core.
Such nozzles often clog, thus causing the manufacturing process to be
temporarily halted until the
nozzle is cleaned. Additionally, such a process is expensive because the
multiple nozzle system is
costly to operate and maintain. Several such nozzles must be used if multiple
strips of material are
wound to form the core. Typically, one application nozzle is used for each
strip of base material,
in addition to one nozzle for applying the liquid thermoplastic material to
the fabric strip.
In Sekar, the base material that forms the core is made of strips of
thermoplastic material,
such as polypropylene. Cores formed of only thermoplastic strips of material
tend to be weaker
than cores formed of other material, such as metal and cardboard strips, thus
the useful life of
such paint rollers is relatively short.
Accordingly, it is an object of the present invention to provide a novel
method of making a
paint roller to substantially overcome the above-described problems.
It is another object of the present invention to provide a novel method of
making a paint
roller that does not use thermoplastic strips as the base material from which
to form the core.
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It is a further object of the present invention to provide a novel method of
making a paint
roller that uses cardboard or metal strips as the base material for the core.
It is also an object of the present invention to provide a novel method of
making a paint
roller that does not require application of any adhesive or liquid
thermoplastic material to the core
once the core has been formed.
It is still an object of the present invention to provide a novel method of
making a paint
roller where cardboard or metal strips pass through an extruder that applies a
layer of liquid
thermoplastic material to the strips before the strips are wound to form the
core.
It is another object of the present invention to provide a novel method of
making a paint
roller that uses a heating device to soften and partially melt a pre-
manufactured strip of
thermoplastic material so as to adhere it to the strips of base material.
SUMMARY
The disadvantages of present methods of making paint rollers are substantially
overcome
with the present invention by providing a novel method of making paint rollers
having a core
formed of non-plastic strips of material.
The present inventive method is more cost efficient and less complex than
known methods
of manufacturing paint rollers. In the present inventive method, liquid
thermoplastic material is
applied only at one point during the formation process. The liquid
thermoplastic material is
applied as the strip of non-plastic material exits the die head, and at no
other point. No liquid
thermoplastic material or adhesive is applied to the wound core at any point.
Accordingly,
additional liquid plastic applicators or nozzle systems are not required,
which are expensive to
operate and maintain. Because the liquid thermoplastic material is applied via
an extruder device,
which is inherently an "on-demand" type of machine, costs are reduced. The
extruder device
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receives and melts plastic pellets on demand, or as needed. This is in
contrast to known systems,
which apply liquid plastic to the core at various points during the formation
of the core. In such
known systems, a reservoir or bath of liquid plastic must be maintained in a
melted state
regardless of the amount of liquid plastic required. This is costly because
the entire reservoir of
plastic must be maintained at a relatively high temperature, and must not be
allowed to cool.
Maintenance and operating costs for such known systems are higher than for the
present inventive
system.
One method of manufacturing a paint roller of one embodiment of the present
invention
includes the steps of providing at least one strip of non-plastic base
material, applying a coating of
liquid plastic to at least one side of the strip of the base material prior to
winding the strip about a
mandril, winding the strip of base material, after application of the liquid
thermoplastic thereto,
about the mandril in a spiral manner, the liquid thermoplastic causing the
strip of base material to
bond forming a core, and winding a strip of fabric material about the core in
a spiral manner, the
liquid thermoplastic material applied to the strip of non-plastic base
material prior to winding
causing the fabric material to bond to the core forming the paint roller.
Another method of manufacturing a paint roller of one embodiment of the
present
invention includes the steps of providing at least one strip of non-plastic
base material, providing
at least one strip of thermoplastic material, partially melting the at least
one strip of thermoplastic
material, applying the partially melted thermoplastic material to at least one
side of the strip of
non-plastic base material, prior to winding about a mandril, winding the strip
of non-plastic base
material, after application of the partially melted thermoplastic material
thereto, about the mandril
in a spiral manner, the partially melted thermoplastic material causing the
strip of non-plastic base
material to be bonded to subsequent spiral layers to form a core; and winding
a strip of absorbent
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material about the core in a spiral manner, where the partially melted
thermoplastic material
applied to the strip of non-plastic base material prior to winding causes the
absorbent material to
bond to the core forming the paint roller.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel are set
forth with
particularity in the appended claims. The invention, together with further
objects and advantages
thereof, may best be understood by reference to the following description in
conjunction with the
accompanying drawings.
Fig. 1 is a side elevational view of a specific embodiment of a device for
making paint
rollers particularly showing multiple strips of base material forming a core,
and a strip of fabric
applied over the core, according to the present inventive method;
Fig. 2 is a front view of an extruder die head, according to the present
inventive method,
taken along the line 2-2 of Fig. 1 in the direction generally indicated;
Fig. 3 is a sectional view of the paint roller, taken along the line 3-3 of
Fig. 1 in the
direction generally indicated;
Fig. 4 is a side elevational view of a specific alternate embodiment of a
device for making
paint rollers particularly showing a heater/melter device for use with strips
of thermoplastic
material;
Fig. S is a side elevational view of a specific alternate embodiment of a
device for making
paint rollers particularly showing a cooling device and an additional heating
device for use with
strips of thermoplastic material; and
Fig. 6 is a perspective view of a push roller.
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DETAILED DESCRIPTION
Referring now to Fig. 1, a roller forming apparatus for manufacturing paint
rollers is
shown generally as 10. The roller forming apparatus 10 utilizes many
components of devices
currently used to produce prior art paint rollers. The roller forming
apparatus 10 includes a
housing 12 to support a stationary mandril 14, and a pair of pulleys 16
coupled to one or more
drive belts 18 that function to advance a wound strip of material along the
stationary mandril to
form a core 20. The pulleys 16 are powered by conventional means, as is known
in the art. A
"fly-away" cutter 22, shown in simplified form, cuts the core 20, which is
otherwise endless, into
useable lengths, as mandated by the particular manufacturing application. The
forming apparatus
may be, for example, a model MS-8 Spiral Tube Cut-Off Saw with Mechanical
Target
Assembly or a Model SAR-42 Semi-Automatic Tube Recutter, both manufactured by
Paco
Winders Manufacturing, Inc.
The apparatus 10 includes one or more plastic extrusion devices 30, die head
assembly
front end 32 coupled to the extrusion device, and in-feed mechanism 34, which
may be part of the
die head assembly. The extrusion device 30 includes a heater tube 36, which
receives a supply of
granular plastic pellets 38 that are melted within the heater tube and are
forwardly advanced
within the tube by a screw-type mechanism. However, any suitable extruder
mechanism may be
used. As the plastic pellets 38 are advanced, the pellets are melted to form a
liquid plastic
material 39. Preferably, the plastic pellets 38 are a thermoplastic material,
such as polypropylene
or similar plastic.
The extrusion device 30 operates in conjunction with the in-feed mechanism 34
to feed a
strip of base material 40 into the dic head assembly 32. The base material may
be, for example,
strips 40 of cardboard, phenolic impregnated paper, chipboard, or thin metal.
The base material
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strips 40 are commercially available and are provided in the form of a roll
(not shown). The in-
feed mechanism 34 directs the strip of base material 40 into the die head
assembly 32. When the
strip of base material 40 enters the die head assembly 32, the melted
thermoplastic material 39 is
applied to one side 42 or both sides 42 and 43 of the strip of base material
so that the strip is
completely coated with the liquid polypropylene 39. In the illustrated
embodiment of Fig. 1, only
the strips of base material 40 labeled as "A" and/or "B" receive the liquid
thermoplastic material
39 on both sides 42 and 43. The strip of base material 40 positioned just
before the belts 18 and
labeled as "C," would receive the liquid thermoplastic material 39 only on its
underside 42 so as
to prevent the liquid thermoplastic material from contacting the belts 18.
An advantage of the present inventive method is that the liquid thermoplastic
material 39
is only applied at one point during the formation process-it is only applied
as the strip of material
40 exits the die head. Once the strip of material 40 leaves the die head
assembly 32 and extrusion
device 30, no additional thermoplastic material 39 is applied to the surface
of the core 20 or to the
wound strips. This reduces costs and improves efficiency. Further, additional
liquid plastic
applicators or nozzle systems are not required, which are expensive to operate
and maintain.
Additionally, the extruder device 30 is inherently an "on-demand" type of
device, which accepts
and melts the plastic pellets 38 on demand, or as needed. In other words, only
the amount of
plastic demanded is melted. This is in contrast to known systems, which apply
liquid plastic to the
core at various points during the formation process. In such known systems, a
reservoir or bath of
liquid plastic must be maintained in a melted state regardless of the amount
of liquid plastic
required. This is costly because the entire reservoir of plastic must be
maintained at a relatively
high temperature and must not be allowed to cool. Maintenance and operating
costs for such
known systems arc higher than for the present inventive system.
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With respect to winding the strips of material 40, the strips of material 40
are fed and
wound about the mandril 14 at an angle so as to form a spiral or helical
pattern when wound. To
begin the process, the free end of the strip of material 40, as supplied from
the roll of material, is
manually wound about the mandril 14 until it extends beyond the drive belts 18
so that the drive
belts tightly surround the wound strips. When the drive belts 18 are engaged
by the pulleys 16, the
wound strip or core 20 is forwardly advanced along the mandril 14. The mandril
14 is formed of
material or is coated with material so that the strips of material 40 do not
"stick." The spiral
pattern has sufficient overlap between spiral layers so that each "wrap" of
the strip of material 40
bonds to adjacent wraps so as to form a strong core. The liquid thermoplastic
39 acts as an
adhesive to bond the wraps of the strip of base material 40 together or to
other strips of base
material. Preferably, three strips of base material 40 are used, which may
comprise, for example,
any combination of strips of thin metal and strips of cardboard.
Alternatively, multiple strips of
cardboard alone may be used without the metal strips. The strips of thin metal
may be made of tin
or aluminum. As shown in Fig. 1, multiple extruder devices 30 or stations are
arranged along the
mandril 14, where each station is substantially the same.
Referring now to Figs. I-2, Fig. 2 shows an elevational view of the die head
assembly 32.
The die head assembly 32 has a rectangular aperture 44 through which the strip
of material 40
exits. The strip of material 40 enters the die head assembly 32 through an
aperture 46. The liquid
thermoplastic material 39 is applied to the strip of material 40 when it is
within the die head
assembly 32, by conventional means, such as by rollers or applicator heads.
Further, the
rectangular aperture 44, in part, functions to regulate the thickness of the
layer of liquid
thermoplastic material 39 applied to the strip of material 40.
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As the core 20 advances along the mandril 14, a strip of absorbent material,
such as fabric
52 or other suitable material capable of absorbing and retaining paint, is
wound about the formed
core 20. The strip of fabric 52 is also provided in the form of a roll 55,
which is initially started by
manually wrapping the first length of the fabric strip about the mandril 14.
It is important to note
that no additional adhesive or liquid thermoplastic material 39 is applied to
either the core 20 or
the fabric strip 52. 'Che temperature of the liquid thermoplastic material 39
applied to the strip of
base material 40 as it exits the die head assembly 32 is sufficiently high so
that the thermoplastic
material remains in a semi-liquid or "tacky" state at the time that the fabric
strip 52 is applied.
This final strip of base material 40 and liquid thermoplastic material 39
shown as "D" is positioned
after the belts 18. In this case, the thermoplastic material 39 is applied to
both upper and lower
surfaces 42, 43 of the base material strip 40 so that when the fabric strip 52
is applied over the
tacky thermoplastic material 39, it becomes permanently banded to the core 20
to form a finished
paint roller 54. Thus, the liquid thermoplastic material 39 applied to the
strip of base material 40
not only bonds the base material to form the core 20, but also bonds the
fabric strip 52 to the core
to form the paint roller 54. A push roller (not shown in this figure) may be
used to press the
fabric strip 52 against the core 20 to aid in forming a strong bond.
After the fabric strip 52 has been applied to and bonded with the core 20, the
fly-away
cutter 22 cuts the paint roller 54 into desirable lengths, as is known in the
art. The position of the
fly-away cutter 22 along the mandril 14 may be changed depending upon the
length of paint roller
manufactured- As shown in Fig. 3, the completed paint roller 54 is shown in
across-sectional
view.
Referring now to Fig. 4, a :specific alternate embodiment is shown where like
reference
numerals are used to denote like strractures. As described above with respect
to Figs. 1-3, a strip
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of base material 40, such as cardboard, chipboard, or thin metal, is provided
in the form of a roll
(not shown). A strip of thermoplastic material 60, such as polypropylene, is
also provided in the
form of a pre-manufactured roll, the width of which is approximately equal to
the width of the
base material strip 40. The strip of thermoplastic material 60 is fed into a
heating unit 62 where it
is softened by heat and partially melted. The heating unit 62 may be a
commercially available
heating device that preferably uses a flame to heat the strip of thermoplastic
material 60 entering
the unit. Alternately, the heating unit 62 may use electrical elements or
heated air to accomplish
the heating function. Again, as described above with respect to Fig. 1, the
strip of base material
40 wound about the mandril 14 that is positioned immediately before the belts
18 receives the
partially melted thermoplastic material only on the interior side 42 so that
the belts do not contact
the layer of partially melted thermoplastic material. The strips of base
material applied to the
mandril 14 positioned after the belts 18 preferably receive the partially
melted thermoplastic
material on the interior and/or exterior surfaces 42 and 43.
The strip of base material 40 may be transported by rollers or another
suitable transport
device (not shown) so that the strip of base material contacts the strip of
partially melted
thermoplastic material 60 shortly after the thermoplastic strip exits the
heating unit 62.
Alternately, depending upon the width of the strips of material used 40 and
60, the strip of base
material 40 may not require any transport rollers or similar structure, and
may simply be unreeled
or pulled from its roll or coil as the mandril 14 rotates. As the
thermoplastic strip 60 exits the
heating unit 62, it is generally parallel to the base material strip 40 and
may be positioned either
directly above or directly below the base material strip, depending upon the
number of heating
units located prior to the belts 18. As shown in Fig. 4, only one heating unit
62 is shown prior to
the belts 18. However, any number of heating units 62 may apply strips of
partially melted
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thermoplastic material 60 to corresponding multiple strips of base material
40, as described with
reference to Fig. 1.
The heating unit 62 provides su~cient heat to partially melt the thermoplastic
strips 60
without causing the material to completely melt and become a liquid. Rather,
it remains as a
partially melted "tacky" strip of thermoplastic material 60. The thermoplastic
strip 60 remains
sufficiently tacky so that upon contact with the strip of base material 40, it
adheres to it forming a
bond with the strip of base material. The base material strip 40 with the
partially melted
thermoplastic material 60 is then wound around the mandril 14 such that the
partially melted strip
of thermoplastic material 60 bonds subsequent turns of the strip of base
material 40 with the
previous turns, thus forming the core of the paint roller 54. A structural
lamination in the form of
a spiral is formed because the overlapping spiral layers of material are
bonded to each other.
Because the strip of thermoplastic material 60 is pre-cut with respect to its
width, and is
typically available in a variety of widths, application of the partially
melted thermoplastic material
60 onto the base material strip 40 is very accurate. No spillage occurs and
undesirable drips are
eliminated. Such drips may cause irregularities on the wound surface or core
20. Application of
the thermoplastic material 60 using the pre-manufactured roll of thermoplastic
material in
conjunction with the heating unit 62 can be controlled precisely because the
thermoplastic
material is not being applied from a reservoir of melted material.
Depending upon the roller size and application, the width of the base material
strip 40 and
thermoplastic strip 60 may vary. As the width of the materials used increases,
use of pre-
manufactured thermoplastic material 60 in the form of a roll becomes more
advantageous because
it is increasingly difficult to accurately apply pre-melted thermoplastic
material to the base
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material strip 40 using an extrusion process, as described with respect to
Fig. 1. Additionally, the
heating unit 62 is cost efficient, and typically is less expensive than
extruder devices.
Referring now to Fig. 5, a specific alternate embodiment is shown where like
reference
numerals are used to denote like structures. In this embodiment, a cooling
device 64 is preferably
used to partially cool the hot strip of thermoplastic material 60 after it is
initially wound on the
mandril 14, but before it contacts the belts 18. Again, multiple strips of
base material 40 and
multiple strips of thermoplastic material 60 (with corresponding heating unit
62) may be used.
This facilitates easier rotation of the belts 18 and assists in eliminating
air bubbles that may
become trapped between the layer of base material 40 and the strip of
thermoplastic material 60.
The cooling device 64 may be a commercially available cooling device that
preferably uses forced
air or cooled air to cool the thermoplastic material. Alternately, the cooling
device 64 may use, for
example, chilled water or a water mist to cool the thermoplastic material. Any
suitable cooling
method may be used. Because the thermoplastic material has been cooled prior
to contact with
the belts 18, the thermoplastic material may be applied to one or both sides
of the strip of base
material 40 without causing build up of plastic on the belts 18. A second
heating device 66 is
placed along the mandril 14 at a point just prior to where the fabric material
52 is applied to
partially re-melts the thermoplastic material so that it again becomes tacky.
The fabric material 52
then bonds to it forming the finished paint roller 54.
A push roller 68 shown in Fig. 6 may be used to apply rolling pressure to the
core 20 to
further aid in bonding the materials together by pressing the fabric material
52 against the hot
thermoplastic material 60. The elongated roller or wheel 68 preferably
contacts the fabric
material 52 after it has been applied to compress the fabric material against
the hot thermoplastic
material 60.
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Specific embodiments of a method and apparatus for making paint rollers
according to the
present inventive method have been described for the purpose of illustrating
the manner in which
the invention may be made and used. It should be understood that
implementation of other
variations and modifications of the invention and its various aspects will be
apparent to those
skilled in the art, and that the invention is not limited by the specific
embodiment described. It is
therefore contemplated to cover by the present invention any and all
modifications, variations, or
equivalents that fall within the true spirit and scope of the basic underlying
principles disclosed
and claimed herein.
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