U.S. patent application number 10/161456 was filed with the patent office on 2003-12-04 for method of processing a laser scored instrument panel with an invisible seam airbag opening.
This patent application is currently assigned to Visteon Global Technologies, Inc.. Invention is credited to Bondar, Robert C., Homburg, Frederick J. JR., Skelly, Jon M..
Application Number | 20030222063 10/161456 |
Document ID | / |
Family ID | 29549291 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030222063 |
Kind Code |
A1 |
Skelly, Jon M. ; et
al. |
December 4, 2003 |
METHOD OF PROCESSING A LASER SCORED INSTRUMENT PANEL WITH AN
INVISIBLE SEAM AIRBAG OPENING
Abstract
A process for forming an instrument panel or other motor vehicle
interior trim component having a laser scored invisible deployment
restraint system opening. Processing of such components having foam
material layers often produces compression forces in the foam. Heat
ageing of the foam causes the compression set to be relieved, which
causes the deployment seam line to become visible. In this
invention the part is heated prior to laser scoring to relieve
compression forces within the foam layer prior to laser
scoring.
Inventors: |
Skelly, Jon M.; (Ann Arbor,
MI) ; Bondar, Robert C.; (Grosse lle, MI) ;
Homburg, Frederick J. JR.; (Woodhaven, MI) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60611
US
|
Assignee: |
Visteon Global Technologies,
Inc.
|
Family ID: |
29549291 |
Appl. No.: |
10/161456 |
Filed: |
June 3, 2002 |
Current U.S.
Class: |
219/121.71 |
Current CPC
Class: |
B29C 59/007 20130101;
B60H 1/2227 20190501; B60R 2013/0287 20130101; B29C 71/02 20130101;
B23K 2103/172 20180801; B23K 2103/50 20180801; B23K 2103/16
20180801; B23K 26/40 20130101; B29L 2031/3008 20130101; B60R
21/2165 20130101; B23K 2103/42 20180801; B29C 2035/0838 20130101;
B29C 2071/022 20130101 |
Class at
Publication: |
219/121.71 |
International
Class: |
B23K 026/38; B23K
026/40 |
Claims
1. A method of processing an automotive interior trim component of
the type forming an opening for a deployable restraint system
comprising the steps of: forming the interior trim component of
multiple layers including a foam layer, the interior trim component
defining an A surface and a B surface, heating the interior trim
component following the forming step at a temperature and time to
substantially relieve compression set of the foam layer at least in
the region of the opening, and scoring the interior trim component
following the heating step using a laser to score the foam layer
such that the scoring is not visible on the A surface.
2. The method of claim 1 wherein the forming step further comprises
the interior trim component having a skin layer forming the A
surface, the foam layer directly underlying the skin layer.
3. The method of claim 1 wherein the forming step further comprises
the interior trim component further having a substrate layer
directly underlying the foam layer and forming the B surface.
4. The method of claim 1 wherein the automotive trim panel is an
instrument panel.
5. The method of claim 1 wherein the forming step further comprises
the interior trim component formed of a laminate injection molded
composite.
6. The method of claim 1 wherein the forming step further comprises
the interior trim component having a skin layer forming the A
surface made of a thermoplastic olefin, the foam layer directly
underlying the top skin layer made of an olefinic foam, an
interlayer directly underlying the foam layer made of a
polypropylene material and a substrate layer directly underlying
the interlayer and forming the B surface and made of a
polypropylene material.
7. The method of claim 1 wherein the heating step further comprises
placing the interior trim component in an oven for a period of
about 30 minutes.
8. The method of claim 1 wherein the heating step further comprises
placing the interior trim component in an oven at a temperature of
about 250.degree. F.
9. The method of claim 1 wherein the heating step further comprises
placing the interior trim component in an oven for a period of
about 30 minutes at a temperature of about 250.degree. F.
10. The method of claim 1 further comprising the step of cooling
the interior trim component to about room temperature following the
heating step.
11. A method of processing an automotive instrument panel of the
type forming an invisible seam opening for a deployable restraint
system comprising the steps of: forming the interior trim component
of multiple layers including a skin layer forming an A surface with
the foam layer underlying the skin layer, the instrument panel
further defining a B surface, heating the interior trim component
following the forming step at a temperature and time to
substantially relieve compression set of the foam layer at least in
the region of the invisible seam opening, and scoring the
instrument panel following the heating step using a laser to score
through the B surface and at least a portion of the foam layer such
that the scoring is not visible on the A surface.
12. The method of claim 11 wherein the forming step further
comprises the interior trim component further having a substrate
layer directly underlying the foam layer and forming the B
surface.
13. The method of claim 11 wherein the forming step further
comprises the instrument panel formed of a laminate injection
molded composite.
14. The method of claim 11 wherein the forming step further
comprises the instrument panel having the skin layer made of a
thermoplastic olefin, the foam layer directly underlying the top
skin layer made of an olefinic foam, an interlayer directly
underlying the foam layer made of a polypropylene material and a
substrate layer directly underlying the interlayer and forming the
B surface and made of a polypropylene material.
15. The method of claim 11 wherein the heating step further
comprises placing the instrument panel in an oven for a period of
about 30 minutes.
16. The method of claim 11 wherein the heating step further
comprises placing the instrument panel in an oven at a temperature
of about 250.degree. F.
17. The method of claim 11 wherein the heating step further
comprises placing the instrument panel in an oven for a period of
about 30 minutes at a temperature of about 250.degree. F.
18. The method of claim 11 further comprising the step of cooling
the instrument panel to about room temperature following the
heating step.
19. A method of processing an automotive instrument panel of the
type forming an invisible seam opening for a deployable restraint
system comprising the steps of: forming the interior trim component
of multiple layers including a skin layer forming an A surface made
of a thermoplastic olefin with a foam layer underlying the skin
layer made of an olefinic foam, an interlayer directly underlying
the foam layer made of a polypropylene material and a substrate
layer directly underlying the interlayer made of a polypropylene
material and defining a B surface, heating the interior trim
component following the forming step at a temperature and time to
substantially relieve compression set of the foam layer at least in
the region of the invisible seam opening, and scoring the
instrument panel following the heating step using a laser to score
through the B surface and at least a portion of the foam layer such
that the scoring is not visible on the A surface.
20. The method of claim 19 wherein the heating step further
comprises placing the instrument panel in an oven for a period of
about 30 minutes.
21. The method of claim 19 wherein the heating step further
comprises placing the instrument panel in an oven at a temperature
of about 250.degree. F.
22. The method of claim 19 wherein the heating step further
comprises placing the instrument panel in an oven for a period of
about 30 minutes at a temperature of about 250.degree. F.
23. The method of claim 19 further comprising the step of cooling
the instrument panel to about room temperature following the
heating step.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a process for forming an
automotive interior trim component and particularly for such a
component which has been subjected to a laser scoring process.
BACKGROUND OF THE INVENTION
[0002] Multi-layer instrument panels for automobiles that
incorporate an invisible seam airbag opening often utilize laser
scoring to weaken the airbag opening to allow for deployment.
During manufacturing, the laser cuts a continuous or perforated
scoring pattern in the substrate through the underside ("B"
surface) of the panel. In a trilaminate panel, the beam generally
cuts through the substrate layer, foam layer, and then partially
into the top skin layer which forms the visible ("A" side) of the
panel. This system produces a weakened opening for a deployable
restraint system in vehicles which is intended to be invisible on
the "A" surface. One drawback of present production parts is that
during heat ageing (as is seen in motor vehicles during natural
life cycles or through validation heat cycling tests), the laser
score line becomes visible on the top "A" surface as an indented
groove or "witness mark" along the score line contour. Conventional
wisdom indicates this is caused by the destruction of the
underlying foam layer (via the laser) and the inability of the void
to support the top skin layer during heating.
BRIEF SUMMARY OF THE INVENTION
[0003] This invention utilizes a pre-heat ageing method step to
prevent the appearance of the witness mark on the "A" surface after
laser scoring. By heat ageing the panel briefly before laser
scoring, the appearance of the line on the "A" surface after laser
scoring is reduced or completely eliminated.
[0004] Additional benefits and advantages of the present invention
will become apparent to those skilled in the art to which the
present invention relates from the subsequent description of the
preferred embodiment and the appended claims, taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a cross-sectional view of an example trilaminate
instrument panel material having a laser scored groove.
[0006] FIG. 2 is a process description flowchart in accordance with
a prior art process.
[0007] FIG. 3 is a process description flowchart of a method in
accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0008] FIG. 1 illustrates a cross-sectional view of an example
motor vehicle instrument panel 10 formed of a trilaminate
configuration. The instrument panel 10 includes a top skin layer
12, foam layer 14, and substrate layer 16. An additional interlayer
17 may also be provided between layers 14 and 16. This composite
structure forms what is known in the industry as an "A" surface 18
which is exposed toward the interior of the associated motor
vehicle, and the backside or "B" surface 20. Various processes for
the forming of instrument panel 10 may be provided. For example,
instrument panel 10 can be a laminate injection molded composite in
which layers 12, 14 and 17 are melt bonded on a substrate 16 made
of a hard or rigid material. During the laminate injection molded
composite process, the foam layer 14 undergoes a compression set,
due to the heat and pressure from injecting the material forming
substrate layer 16 behind the trilaminate (layers 12, 14 and 17).
This same compression set of the foam layer 14 is also created
during the manufacturing of other trilaminate and bilaminate
manufacturing process as well as other thermal forming processes.
This compression set is released during heat ageing of instrument
panel 10 as the foam layer 14 expands back toward its original
thickness. Such heat aging occurs during normal exposure of
instrument panel 10 to thermal cycles during its normal use in a
motor vehicle, or during thermal cycling testing of the instrument
panel. This tendency of relief of compression set causes the
previously noted witness lines to appear on the instrument "A"
surface 18.
[0009] FIG. 1 further illustrates a laser score groove 22. Laser
scoring involves the use of a controlled laser light beam which is
directed against the "B" surface 20 and destroys the substrate and
foam layer 14 to create an opening for deployment of an associated
airbag module (not shown). Laser score groove 22 weakens instrument
panel 10 in a precise manner such that skin layer 12 will tear
along score line 26 aligned with score groove 22. This allows
interior trim components, including instrument panels, to be formed
which have airbag openings which are invisible to the motor vehicle
occupant (viewing "A" surface 18). However, as mentioned
previously, heat ageing of instrument panel 10 in use causes a
release of the compression set of foam layer 14.
[0010] The interactions between foam layer 14 and skin layer 12
differ in the area where the foam layer 14 supports skin layer 12,
and where it is removed in the area of score groove 22. Laser score
groove 22 imposes an impediment to the release of the compression
set and the expansion of the foam of foam layer 14. Score groove 22
is formed by burning caused by the laser light which makes the
inside lining of score groove 22 hard and stiff. A U-shaped channel
28 (inverted as illustrated) of melted foam 24 is developed. Melted
foam layer 24 acts like a solid plastic member having structural
and compression characteristics differing from that of the
remaining foam forming foam layer 14. This "tube" formed by channel
28 also becomes welded to the underside of skin layer 12 which
mechanically anchors skin layer 12 to the underlying substrate
layer 16. When the foam of foam layer 14 begins to release its
compression set and expand during subsequent heating, the "tube" of
channel 28 cannot expand and therefore holds the skin layer 12 in
place. This "tube" becomes an anchor for the skin layer 12 at score
line 26. The surrounding foam of foam layer 14 expands, releasing
its compression set while the score line 26 above score groove 22
does not. This creates a depressed groove along the laser score
line 26. The groove is not, as previously believed, caused by the
foam 14 compressing along the score line 26 and sinking under the
weight of the skin, but rather by the expansion of the foam of foam
layer 14 around the score line 26, while the skin layer 12 material
along line 26 itself remains stationary. It is this new
understanding of the mechanism of failure that gives rise to the
method of this invention to correct the problem.
[0011] The appearance of such witness lines may also occur in
irregular and unpredictable manner. Not only is the appearance of
any witness line undesirable where the object is to produce an
invisible airbag seam, but further such witness lines may be
irregular in appearance around the perimeter of the airbag
opening.
[0012] Laser scoring to form score groove 22 may be accomplished by
numerous processes. One such process is described by U.S. Pat. No.
5,744,776 which is hereby incorporated by reference. Laser scoring
processes typically use a CO.sub.2 gas laser which creates a beam
focused to a point. The beam may be advanced continuously to create
score groove 22 which forms an invisible seam airbag deployment
opening. Alternatively, the scoring can be a series of closely
spaced holes forming a score groove 22 through closely spaced
perforations. In either instance, however, the disadvantage of the
prior art noted previously appears.
[0013] Now with reference to FIG. 2, a flowchart for processing
instrument panel 10 in accordance with the prior art method is
illustrated. Step 30 designates the beginning of the process. The
part is removed from an injection mold at step 32. This step could
also include any other type of processing in which a final
instrument panel 10 (or other type of panel) is produced.
Thereafter, instrument panel 10 is stored for further processing at
step 34. Next, the instrument panel 10 is loaded into a laser
scoring fixture at step 36. Parts handling equipment next moves
instrument panel 10 to a laser scoring station at step 38. Laser
scoring through any one of a number of potential process as
described previously occurs at step 40, yielding a scored
instrument panel 10 at step 42.
[0014] Now with reference to FIG. 3, a process in accordance with
the present invention is illustrated. In this invention the
instrument panel 10 is preheated to release the foam compression
set prior to the laser scoring step. This is illustrated in the
additional steps 44 through 50 shown in FIG. 3. Those steps which
are common between FIGS. 2 and 3 are identified by like reference
numbers.
[0015] After the instrument panel 10 is removed from mold at step
32 it is transferred to a dimensional holding fixture at step 44.
This holding fixture is designed to maintain the dimensional
integrity of instrument panel 10 during further processing steps
will now be described. Once fastened the holding fixture at step 44
instrument panel 10 is moved into an oven or another station where
it is heated at step 46. As stated previously, this heating is
designed to release internal compression set forces within foam
layer 14 acting on the instrument panel 10 structure. Thereafter,
the part is cooled to room temperature at step 48 and is finally
removed from the holding fixture at step 50. Next, the part enters
the process stream beginning at step 34 as previously described and
at step 40 is laser scored.
[0016] When the instrument panel 10 has finally been scored at step
40, the foam layer 14 has already expanded to its maximum
thickness. Further heat aged testing does not produce a previously
mentioned "groove" or witness line because foam 14 no longer
expands.
[0017] As an example of implementation of the process of this
invention, a Visteon Laminate Injection Molded (VLIM) instrument
panel 10, such as that seen on the Mazda Tribute (J14) vehicle is
used in this example. In this case, the instrument panel design
includes a seamless airbag opening on the passenger side. The
trilaminate skin is a thermoplastic olefin (TPO) skin layer 12, an
olefinic foam middle layer 14, with a polypropylene based
interlayer 17. The substrate layer 16 is a talc filled
polypropylene such as ATX 832 produced by ATC, Inc., which is
commercially available. The instrument panel 10 is placed in a
heating oven at 230.degree. F. for 30 minutes, prior to laser
scoring. The part is then allowed to cool to room temperature
before laser scoring the airbag door opening. The part is then used
in the usual fashion for production.
[0018] Various alternatives can be implemented in accordance with
the present invention. For example, various other heating times
have been experimented with. It was found that 15 minute exposure
at 250.degree. F. in step 46 also produced the desired result for
the previous mentioned material system comprising instrument panel
10. Alternate methods of heating may also be implemented, for
example, a portable heating element to locally heat the airbag
opening area of instrument panel 10 or a heating bank used directly
after molding at step 32 while the parts are on a fixture as may be
required. In any event, the concept of this invention involves
essentially the full release of compression set of the foam layer
14 prior to laser scoring. Experiments utilizing the process of
this invention reveal no discernable witness lines following heat
ageing cycling tests which are required by many original equipment
manufacturers (OEM) customers.
[0019] In addition to instrument panels, there are numerous other
interior trim components of motor vehicles which conceal airbag
modules. For example, side impact airbags and side curtain airbag
systems may be mounted to motor vehicle seats, door trim panels,
headliners or various pillar structures of the motor vehicle
interior compartment. For many of these applications, it is
desirable to conceal the deployable restraint system and such
concealment may be provided by laser scoring. Accordingly, this
invention may also be implemented in connection with interior trim
components in addition to instrument panels. The invention is
believed best adapted for such applications where compression set
forces act on the surface forming the panel's "A" surface.
[0020] While the above description constitutes the preferred
embodiment of the present invention, it will be appreciated that
the invention is susceptible to modification, variation and change
without departing from the proper scope and fair meaning of the
accompanying claims.
* * * * *