U.S. patent application number 10/385116 was filed with the patent office on 2003-08-07 for method for attaching fibrous batt to plastic substrate.
Invention is credited to Bearman, John A., Hoeksema, Bret A..
Application Number | 20030146544 10/385116 |
Document ID | / |
Family ID | 23902700 |
Filed Date | 2003-08-07 |
United States Patent
Application |
20030146544 |
Kind Code |
A1 |
Bearman, John A. ; et
al. |
August 7, 2003 |
Method for attaching fibrous batt to plastic substrate
Abstract
An improved, economical, high speed method for attaching a
fibrous material to a plastic substrate involves positioning a
fibrous material over a surface of a plastic substrate, directing a
stream of heated air through the fibrous material and at the
surface of the plastic substrate to melt the surface of the plastic
substrate, compressing the fibrous material against the melted
surface of the plastic substrate, and allowing the melted surface
of the plastic substrate to cool and resolidify, whereby fibers of
the fibrous material become embedded in the resolidified
plastic.
Inventors: |
Bearman, John A.;
(Hudsonville, MI) ; Hoeksema, Bret A.; (Zeeland,
MI) |
Correspondence
Address: |
PRICE HENEVELD COOPER DEWITT & LITTON
695 KENMOOR, S.E.
P O BOX 2567
GRAND RAPIDS
MI
49501
US
|
Family ID: |
23902700 |
Appl. No.: |
10/385116 |
Filed: |
March 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10385116 |
Mar 10, 2003 |
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09479111 |
Jan 7, 2000 |
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6530773 |
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Current U.S.
Class: |
264/322 |
Current CPC
Class: |
B29C 66/45 20130101;
B29C 66/7394 20130101; B29L 2031/3014 20130101; B29K 2023/12
20130101; B29L 2031/3008 20130101; B29C 66/8242 20130101; B29L
2031/3005 20130101; B29C 66/8122 20130101; B29C 66/8167 20130101;
B29C 66/92653 20130101; B29C 66/7392 20130101; B29K 2067/00
20130101; B29C 66/8322 20130101; B29C 66/1122 20130101; B29K
2055/02 20130101; B29C 65/08 20130101; B29C 66/21 20130101; B29C
66/80 20130101; B29K 2995/0002 20130101; B29C 66/73921 20130101;
B29C 65/10 20130101; B29C 66/71 20130101; B29C 66/8122 20130101;
B29K 2909/02 20130101; B29C 66/8122 20130101; B29K 2905/10
20130101; B29C 66/8122 20130101; B29K 2905/08 20130101; B29C 66/71
20130101; B29K 2067/003 20130101; B29C 66/71 20130101; B29K 2055/02
20130101; B29C 66/71 20130101; B29K 2023/12 20130101 |
Class at
Publication: |
264/322 |
International
Class: |
B29C 031/00 |
Claims
The invention claimed is:
1. A method of attaching a fibrous material to a plastic substrate
comprising: positioning the fibrous material over a surface of the
plastic substrate; directing a stream of heated air through the
fibrous material and at the surface of the plastic substrate, the
quantity and temperature of the heated air being sufficient to melt
the surface of the plastic substrate; compressing the fibrous
material against the melted surface of the plastic substrate to
cause fibers of the fibrous material to become immersed in the
melted surface of the plastic substrate; and allowing the melted
surface of the plastic substrate to cool and resolidify, thereby
embedding fibers of the fibrous material in the resolidified
plastic.
2. The method of claim 1, wherein the fibrous material is
compressed by pressing a workpiece-engaging surface of a tool
against the fibrous material, and wherein the stream of heated air
is directed from the workpiece-engaging surface of the tool.
3. The method of claim 2, wherein the workpiece-engaging surface of
the tool is substantially flat.
4. The method of claim 3, wherein the workpiece-engaging surface of
the tool includes a plurality of passageways in communication with
a supply of heated, pressurized air.
5. The method of claim 4, wherein the plurality of passageways
include a single passageway located at the center of the
workpiece-engaging surface of the tool, and the remaining
passageways are located near an edge of the workpiece-engaging
surface of the tool.
6. The method of claim 5, wherein each of the passageways, except
for the passageway at the center of the workpiece-engaging surface,
are about {fraction (1/16)} inch or less from an edge of the
workpiece-engaging surface.
7. The method of claim 4, wherein the workpiece-engaging surface of
the tool has exactly five passageways including a passageway
located at the center of the workpiece-engaging surface, and with
each of the other four passageways located near an edge of the
workpiece-engaging surface.
8. The method of claim 7, wherein each of the passageways located
near the edge of the workpiece-engaging surface is about {fraction
(1/16)} inch or less from an edge of the workpiece-engaging
surface.
9. The method of claim 6, wherein the passageways near the edge of
the workpiece-engaging surface are uniformly angularly spaced apart
around the center of the workpiece-engaging surface.
10. The method of claim 2, wherein the tool is made of brass.
11. The method of claim 2, wherein the tool is made of ceramic.
12. The method of claim 2, wherein the cumulative cross-sectional
area of the passageways is about equivalent to the cross-sectional
area of a single one-quarter inch diameter passageway.
13. The method of claim 8, wherein each of the passageways has a
cross-sectional diameter of about 0.063 inches.
14. The method of claim 1, wherein the fibrous material is a shotty
comprised of shredded and needled plastic materials.
15. The method of claim 1, wherein the fibrous material is
comprised of natural fibers, synthetic fibers, glass fibers or a
combination thereof.
16. The method of claim 1, wherein the plastic substrate is a
polypropylene substrate, and ABS substrate, or a PET substrate.
17. The method of claim 1, wherein the flow rate of the directed
stream of heated air through the fibrous material is about 80
SCFM.
18. The method of claim 1, wherein the fibrous material is
compressed at a pressure of about 80 psi.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a method for attaching a fibrous
batt of material, such as sound absorbing material, to a heat
fusible plastic substrate.
BACKGROUND OF THE INVENTION
[0002] Sound absorbing fibrous materials or batts are commonly
attached to the inner wall of plastic interior automotive panels to
absorb sound and reduce noise in the passenger compartment of
automobiles. The fibrous materials deaden noises generated by
vibrating parts in the automobile and give the driver and
passengers a feeling of riding in a more solid, well built vehicle.
Among the most commonly employed sound absorbing materials used are
shotties, which are fibrous sound insulating batts made by
shredding and needling scrap and/or recycled materials, typically
scrap and/or recycled plastics such as polypropylene,
acrylonitrile-butadiene-styrene terpolymer (ABS), polyethylene
terephthalate (PET), etc. Other examples of fibrous sound absorbing
materials include glass fiber, synthetic fiber, natural fiber (such
as wool, cotton, etc.), and combinations thereof.
[0003] Sound absorbing fibrous materials are typically attached
with adhesives to various plastic automotive interior panels, such
as door panels, interior trim panels, pillar panels, headliners,
dashes, lift-gate panels, visors, and the like. A disadvantage with
the use of adhesives for attaching fibrous sound absorbing
materials to plastic automotive interior panels is that a
relatively high cycle time is required for each part, regardless of
whether the adhesive is applied manually or with automated
equipment. In either case, the equipment used to apply the adhesive
is prone to require significant maintenance, especially on account
of the tendency for plugging to occur at spray nozzles, metering
orifices, and the like. Adhesives are also relatively expensive. A
further disadvantage with adhesives is that there is inevitably a
certain amount of adhesive material which will become air-borne
during application and will pollute the immediate environment,
presenting possible health concerns and requiring frequent cleaning
of surfaces where air-borne adhesives accumulate.
[0004] In an effort to eliminate the use of adhesives for attaching
a fibrous sound absorbing material to plastic automotive interior
panels, ultrasonic welding has been employed. Ultrasonic welding
techniques involve the generation of high frequency vibrations
which are directed toward a location on a plastic substrate, such
as an automotive body panel. The vibrations cause polymer molecules
at a selected location of the plastic substrate to vibrate and heat
up to the melting point of the plastic. Thereafter, the fibrous
material is pressed against the melted plastic and becomes
physically bound to the plastic substrate as the melted plastic
cools and resolidifies. Although the use of ultrasonic welding
eliminates the need for adhesives, it is a relatively slow process,
particularly for larger panels in which a plurality of welds are
needed to securely attach the fibrous sound absorbing material to
the plastic panel. Because of the high cost of ultrasonic welding
equipment, a single ultrasonic welding device is used to
sequentially create a plurality of welds for a single part. As a
result, cycle times are relatively high, and ultrasonic welding
does not, in practice, provide a substantial cost advantage over
adhesives.
[0005] Therefore, there remains a need for an economical method and
apparatus for attaching a fibrous sound absorbing material to a
plastic substrate without adhesives.
SUMMARY OF THE INVENTION
[0006] The invention provides an improved, economical, high speed
method for attaching a fibrous material to a plastic substrate.
[0007] The method of attaching a fibrous material to a plastic
substrate involves positioning the fibrous material over a surface
of the plastic substrate, and directing a stream of heated air
through the fibrous material and at the surface of the plastic
substrate which is under the fibrous material. The quantity of air
and the temperature of the heated air are sufficient to melt the
surface of the plastic substrate which is under the fibrous
material. After the surface of the plastic substrate has melted,
the fibrous material is pressed against the melted surface of the
plastic substrate to cause the fibers of the fibrous material to
become immersed in the melted plastic at the surface of the plastic
substrate. After the fibers are pressed against the melted plastic,
the melted surface of the plastic substrate is allowed to cool and
resolidify. The fibers which were immersed in the melted plastic
become embedded in the resolidified plastic, thus providing a
durable physical bond between certain individual fibers of the
fibrous material and the surface of the plastic substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a side elevational view, partially in cross
section, of an apparatus for attaching a fibrous material to a
plastic substrate in accordance with the principles of this
invention, with the tool positioned above the plastic substrate and
fibrous material, before the fibrous material is attached to the
plastic substrate;
[0009] FIG. 2 is a side elevational view, partially in cross
section, of the apparatus shown in FIG. 1, with the tool
reciprocated downwardly into the fibrous material to achieve
attachment of the fibrous material to the underlying plastic
substrate;
[0010] FIG. 3 is a side elevational view, partially in cross
section, of the apparatus, fibrous material, and plastic substrate
shown in FIGS. 1 and 2, after the tool has been reciprocated away
from the fibrous material and plastic substrate, after the fibrous
material has been attached to the plastic substrate;
[0011] FIG. 4 is an enlarged side elevational view of the tool
shown in FIGS. 1-3;
[0012] FIG. 5 is a bottom view of the tool shown in FIG. 4;
[0013] FIG. 6 is a top view of the tool shown in FIGS. 4 and 5;
[0014] FIG. 7 is a fragmentary side view, partially in cross
section, of a modified apparatus in accordance with the principles
of the present invention; and
[0015] FIG. 8 is a perspective of the adjustable support components
of the apparatus of FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] An apparatus 10 for attaching a fibrous material 12 to a
plastic substrate 14 is shown in FIGS. 1-3. In the illustrated
embodiment, apparatus 10 includes a fixture 16 for supporting
plastic substrate 14 and fibrous material 12, with fibrous material
12 generally positioned over plastic substrate 14. Fixture 16 is
mounted on a platform 18. A support structure 19 is also mounted on
platform 18. Support structure 19 supports a workpiece-engaging
tool 20, and an actuator 22 for reciprocating workpiece-engaging
tool 20 between a first position (as shown in FIGS. 1 and 3) in
which workpiece-engaging tool 20 is spaced away from the surface of
plastic substrate 14 and away from the overlying fibrous material
12, and a second position (as shown in FIG. 2) in which
workpiece-engaging tool 20 compresses fibrous material 12 against a
surface of plastic substrate 14. Illustrated actuator 22 is a
pneumatic actuator comprising a cylinder 24 and a piston or rod 26
which reciprocates within cylinder 24. Piston 26 is fixed, at its
lower end, to support structure 19. Attached to a lower end of
cylinder 24 is a bracket 28 on which an air supply tube 30, air
heater 32, and workpiece-engaging tool 20 are supported. Lower
bracket 33 is fixed to air heater 32, and includes a bearing that
slidably engages the lower end 26A of piston 26. Air can be
supplied to air tube 30 by a flexible air supply line 34.
[0017] Although illustrated actuator 22 is a pneumatic actuator,
actuator 22 may, as an alternative, be a hydraulic actuator, a
motor driven screw type linear actuator, or any other suitable
mechanical actuator for reciprocating workpiece-engaging tool 20
toward and away from fixture 16, plastic substrate 14, and
overlying fibrous material 12.
[0018] Although air heater 32 is preferably an electrical
resistance heater, it is conceivable that other types of heating
devices may be employed, such as a hot oil to air heat
exchanger.
[0019] As shown in FIGS. 4-5, the illustrated workpiece-engaging
tool 20 is a plug-like fitting, including a threaded upper portion
36 which can be screwed to a coupling 38 connected to the lower end
of air supply tube 30. The bottom of workpiece-engaging surface 40
conforms with the surface of plastic substrate 14 at which fibrous
material 12 is attached to plastic substrate 14. In most cases, it
is desirable that workpiece-engaging surface 40 be substantially
flat because in general, it will be desirable to attach the fibrous
material 12 to a flat surface of plastic substrate 14. However, the
workpiece-engaging surface 40 of workpiece-engaging tool 20 can be
curved, such as cylindrical or hemispherical, or comprised of two
or more intersecting planar surfaces, to conform with more
complicated surfaces of a plastic substrate if desired. In the
illustrated embodiment, workpiece-engaging tool 20 includes five
parallel bores or passageways 42 which extend longitudinally
through the plug-like tool 20 from an upper surface 44 which is in
fluid communication with air supply tube 30, to the
workpiece-engaging surface 40, which is in contact with fibrous
material 12 (as shown in FIG. 2) during the attachment operation.
Also, the workpiece-engaging tool 20 includes two perpendicular
grooves 47 formed on the flat end surface of the tool. The grooves
47 form a pair of crisscrossed raised ribs of fibrous material in
the fibrous material 12 on the plastic substrate 14 that help
stiffen and stabilize the fibrous material at the point of
attachment, thus helping assure a good bond. The grooves 47 can
also act as funnels for controlling air flow in a manner providing
a more even distribution of heat. As illustrated, the bores 44 are
positioned outside of the grooves 46, but they may also be
positioned in the bores 44 if desired.
[0020] The invention has been illustrated with respect to a fibrous
material 12 attached to plastic substrate 14 with an apparatus
comprising a single tool for bonding the fibrous material 12 to
plastic substrate 14. However, in most cases a plurality of tools
would be used simultaneously for fusing fibrous material 12 to
plastic substrate 14 at a plurality of different locations. For
example, in the case of a relatively large plastic substrate 14,
such as a door panel, it may be desirable to utilize twelve
apparatuses 10 simultaneously to bond fibrous material 12 to a door
panel at, for example, five to twenty distinct areas.
[0021] Fibrous material 12 is attached to plastic substrate 14 by
first positioning plastic substrate 14 in registry with fixture 16,
and thereafter positioning fibrous material 12 over plastic
substrate 14, as shown in FIG. 1. Thereafter, actuator 22 is
activated causing workpiece-engaging tool 20 to be displaced toward
plastic substrate 14, compressing fibrous material 12 between
plastic substrate 14 and workpiece-engaging surface 40 of tool 20.
Hot air is blown through passageways 42 of tool 20, through fibrous
material 12, and impinges upon a surface of plastic substrate 14,
causing a surface portion 46 of plastic substrate 14 to melt. The
pressure imposed upon fibrous material 12 by workpiece-engaging
tool 20 causes fibers of fibrous material 12 to become immersed in
melted plastic 46. Thereafter, tool 20 is reciprocated away from
fibrous material 12, as shown in FIG. 3, and melted plastic portion
46 cools and resolidifies causing fibers of fibrous material 12 to
become embedded within plastic substrate 14, thereby forming a
strong physical bond between fibrous material 12 and plastic
substrate 14. At the point of attachment, the fibrous material 12
forms a depression 46A having a pair of raised ribs of fibrous
material in the shape of the grooves 47 that criss-cross the
depression 46A in a manner adding strength to the fibrous material
at the attachment.
[0022] Suitable plastic substrates generally include any of the
thermoplastic materials typically employed in automotive interior
panels, such as polypropylene, ABS, PET, etc. The fibrous material
12 is generally any fibrous material commonly employed in the
automotive industry for sound absorption. Suitable sound absorbing
fibrous materials include non-woven batts comprised of glass
fibers, synthetic fibers, including shredded thermoplastic and/or
thermoset resins, natural fibers, and combinations thereof.
[0023] The flow rate of hot air emerging from tool 20, penetrating
fibrous material 12, and impinging upon plastic substrate 14, to
melt a portion of plastic substrate 14, depends upon a variety of
factors, including the thickness, composition and density of
fibrous material 12, the melting point temperature of plastic
substrate 14, and the desired area of the bond between fibrous
material 12 and plastic substrate 14. Other factors which may be
considered include the contact time between tool 20 and fibrous
material 12, and the number, size and hole pattern for passageways
42. In the illustrated embodiment, workpiece-engaging surface 40 is
approximately square, with dimensions of 3/8 inches by 3/8 inches.
It has been found that for the illustrated tool, a hot air flow
rate of about 80 standard and cubic feet per minute (SCFM), heated
with a 400-watt heater, can be used to bond a quarter inch thick
shotty to polypropylene in about 6 seconds. A suitable diameter for
each of the five passageways 42 is about 0.063 inches. Smaller or
larger passageways 42 may be used if desired. However, it is
desirable that the cumulative cross-sectional area of all of the
passageways 42 should be about equivalent to the cross-sectional
area of a single one-quarter inch diameter passageway when a flow
rate of 80 SCFM is used with a 400-watt heater. A plurality of
passageways 42, such as five, is preferred as compared to a single
passageway having an equivalent cross-sectional area. This is
because a single one-quarter inch passageway tends to concentrate
too much heat into too small of an area, causing certain fibrous
materials, such as typical shotties to burn or otherwise
deteriorate. A suitable pressure of tool 20 on fibrous material 12
is about 80 psi, although this can be varied as desired depending
upon the fibrous material employed. Tool 20 can be made from
generally any machinable material, with brass currently being a
preferred material. However, it is believed that a ceramic tool may
have advantages, because it will remain cooler, whereby more heat
will be directed toward plastic substrate 14, where it is most
desired, not at fibrous material 12.
[0024] A four passageway 42 pattern as shown in FIGS. 5 and 6 is
most preferred, as it provides uniform heating and results in an
excellent bond between a typical substrate (e.g., polypropylene)
and typical shotty batts. Preferably a plurality of edge
passageways engaging surface 40 are preferred, with the edge
passageways preferably being about {fraction (1/16)} inch or less
from the edge of workpiece-engaging surface 40. The edge
passageways are preferably uniformly angularly spaced apart around
the center of workpiece-engaging surface 40, irrespective of
whether there is a cooler passageway.
[0025] A modified apparatus 10A (FIGS. 7-8) includes features and
components that are similar to and/or that are identical to the
apparatus 10. In modified apparatus 10A, these similar and
identical features and components are identified by using identical
numbers along with a letter "A". This is done to reduce redundant
discussion, and not for another reason.
[0026] The support structure 19A includes a plate 50A (FIG. 8)
having an opening 51A. An L bracket 52A includes a first leg 53A
attached by two bolts 54A and 55A that extend through a hole 56A
and a slot 57A into threaded holes in the plate 50A. The slot 57A
extends arcuately around the hole 56A, such that the L bracket 52A
can be rotated even with the bolts 54A and 55A in place.
Specifically, by loosening the bolts 54A and 55A, the bracket 52A
can be angularly adjusted by rotation about hole 56A to a desired
position. Thereafter, the bolts 54A and 55A are re-tightened to
hold the selected position. The bracket 52A includes a second leg
60A that extends downwardly. A C-shaped bracket 61A includes a
vertical leg 62A and top and bottom horizontal legs 63A and 64A.
The vertical leg 62A abuts the second leg 60A, and is secured to
the second leg 60A by bolts 65A and 66A that extend through a hole
67A and slot 68A into threaded holes in the vertical leg 62A. By
loosening the bolts 65A and 66A, the bracket 61A can be anularly
adjusted by rotation about hole 67A to a desired position.
Thereafter, the bolts 65A and 66A are re-tightened to hold the
selected position. This "two angle" adjustment is important because
it allows an operator to setup the apparatus 10A so that the tool
20A extends perpendicularly into engagement with the fibrous
material 12A and substrate 14A, despite angled surfaces 13A that
occur in the substrate 14A.
[0027] Cylinder 24A of actuator 22A is attached to the top leg 63A,
and the extendable rod 26A (the lower end of which is hex shaped in
cross section to resist rotation) extends through the top leg 63A
and through the bottom leg 64A, slidably engaging the bottom leg
64A. The actuator 22A is connected to a fluid source as previously
described in regard to apparatus 10. A bracket 33A is attached to
the lower end of the rod 26A, and includes a first bracket plate
70A attached directly to the rod 26A and a second bracket plate
72A. A threaded stop rod 74A is threaded into the first bracket
plate 70A, and is adjusted to a position where the stop rod 74A
will engage a stop on the tool 16A to prevent damage to the
apparatus 10A. The second bracket plate 72A is bolted to the first
bracket plate 70A by bolts 76A and 78A, with the bolt 76A extending
through a hole and the bolt 78A extending through a slot in the
second plate 72A. Thus, the second bracket plate 72A is angularly
adjustable in a fashion similar to the earlier described
arrangements for pairs of bolts 54A and 55A, and also bolts 65A and
66A. This allows for quick and easy adjustment at the point of use
of apparatus 10A, even when the equipment is hot.
[0028] An elongated batt-holder device 80A (FIG. 7) includes a
bracket plate 82A attached to the plate 50A (either to its top
surface or its bottom surface) by bolts 84A and 86A. Where desired,
the bolts 84A and 86A can extend through a hole and slot as
previously described in regard to bolts 65A and 66A, thus allowing
adjustability of the bracket plate 82A. A rigid rod 88A extends
downwardly from the bracket plate 82A. A pressure foot 89A includes
a threaded rod 90A that threadingly engages a threaded hole in the
end of the rigid rod 88A, and further includes a rubber foot 92A.
By adjusting the threaded rod 90A and locking it in an adjusted
position by the lock nut 94A, the foot 92A can be adjusted so that
it contacts the fibrous material 12A and substrate 14A to hold them
in position while the apparatus 10A works.
[0029] During operation of apparatus 10A, the fixture 16A is
initially raised, such that the fibrous material 12A and substrate
14A come into contact with the foot 92A. The actuator 22A extends
piston 26A, causing the assembly of the bracket plate 70A and 72A
and air supply heater 30A to extend and heat the selected location,
which results in the melted plastic 46A. The actuator 22A extends
about {fraction (1/16)} inch to 1/4 inch when it is extended,
causing the tool 20A to press the fibrous material 12A against the
substrate 14A. After a surface of the substrate is melted, the
pressure is held for a short time, which results in the depression
46A (FIG. 1).
[0030] Although the invention has been described with respect to
attachment of fibrous material to automotive interior panels, such
as door panels, interior trim panels, pillar panels, headliners,
dashes, lift-gate panels, and visors, the apparatus and methods of
the invention can be employed for attaching any of a variety of
fibrous materials, especially non-woven fibrous batts, to any of a
variety of thermoplastic substrates, for generally any
application.
[0031] It will become apparent to those skilled in the art that
various modifications to the preferred embodiments of the invention
can be made without departing from the spirit or scope of the
invention as defined by the appended claims.
* * * * *