Title: Skin and manufacturing method thereof, manufacturing method of skin for air bag door and air bag door
Abstract: The present invention intends to provide an air bag door construction in which the air bag develops smoothly and securely, the skin can be easily produced with small man-hour, and which is excellent in the surface appearance.The skin 50 is formed by a mold 5 including an endless and annular wall 50 provided at a part of a molding surface to be inclined relative to the molding surface. A groove portion 35 of the skin 3 formed by the wall 50 is cut at a bottom portion thereof to separate the skin 3 into a general portion 30 and a door portion 31. The general portion 30 and the door portion 31 are relatively shifted to make both surfaces thereof flush with each other.When the surfaces of the general portion 30 and the door portion 31 are flush by the relative shift, gap between the general portion 30 and the door portion 31 can be narrowed, and gap appeared on the surface can also be narrowed. Also, when the skin is disposed in the mold for foam forming, the skin can position the general portion 30 and the door portion 31 in the desired position easily, and will not scatter a skin chip in the development of the air bag.
Patent Number: 7,014,901 Issued on 03/21/2006 to Sanae, et al.
| Inventors:
|
Sanae; Shoji (Komaki, JP);
Ueno; Shigehiro (Kasugai, JP);
Nagano; Akiyoshi (Ama-gun, JP);
Suyama; Hiroshi (Gifu, JP);
Nakano; Akio (Nagoya, JP)
|
| Assignee:
|
Tokai Chemical Industries, Ltd. (Komaki, JP);
Toyoda Goset Co., Ltd. (Nishikasugai-gun, JP)
|
| Appl. No.:
|
358193 |
| Filed:
|
February 5, 2003 |
Foreign Application Priority Data
| Jun 03, 1999[JP] | 11-156390 |
| Mar 28, 2000[JP] | 2000-88157 |
| Current U.S. Class: |
428/57; 428/58; 428/119; 428/319.3; 280/728.3; 280/732 |
| Current Intern'l Class: |
B32B 3/00 (20060101) |
| Field of Search: |
428/3193,76,126-129,57,58,119
280/7283-732
|
References Cited [Referenced By]
U.S. Patent Documents
| 4459256 | Jul., 1984 | Ziegler.
| |
| 4893833 | Jan., 1990 | DiSalvo et al.
| |
| 4952351 | Aug., 1990 | Parker et al.
| |
| 5478107 | Dec., 1995 | Yamagishi et al.
| |
| 6062590 | May., 2000 | Gallagher.
| |
| 6447004 | Sep., 2002 | Kawakubo et al.
| |
| Foreign Patent Documents |
| 198 31 462 | Jan., 2000 | DE.
| |
| 1-202550 | Aug., 1989 | JP.
| |
| 5-294196 | Nov., 1993 | JP.
| |
| 6-285876 | Oct., 1994 | JP.
| |
| 7-156737 | Jun., 1995 | JP.
| |
| 07-329683 | Dec., 1995 | JP.
| |
| 11-222089 | Aug., 1999 | JP.
| |
Primary Examiner: Vo; Hai
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a divisional application of, and claims priority under
35 U.S.C. §122, of U.S. application Ser. No. 09/585,276 ("the parent application"),
filed Jun. 2, 2000, now U.S. Pat. No. 6,632,388 whose entirety is hereby incorporated
by reference herein.
Claims
What is claimed is:
1. A vehicle interior article comprising a resin base member, a skin and an intermediate
foamed body layer, said skin including at a part thereof an annular groove portion
defining a general portion and a defined portion enclosed by the annular groove
portion and being provided with a parting line where the skin is separated into
the general portion and the defined portion, wherein:
said general portion has an annular end portion having a first bent portion facing
the groove portion, and said defined portion has an annular end portion having
an annular second bent portion facing the groove portion; and
wherein the second bent portion is inwardly inclined by an acute angle relative
to the surface of the defined portion.
2. A vehicle interior article according to claim 1, wherein said defined portion
is an air bag door portion.
3. A vehicle interior article according to claim 1, wherein said acute angle
of the second bent portion relative to the surface of the defined portion is respectively
selected to be 65 to 85 degrees.
4. A vehicle interior article according to claim 1, wherein the inward inclination
of the second bent portion, which is inwardly inclined by the acute angle respectively
relative to the surface of the defined portion, is contiguous with the surface
of the defined portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a skin used to form a surface such as a vehicle interior
panel and manufacturing method thereof, and to a manufacturing method of skin for
air bag door and an air bag door.
2. Related Art
For protecting passenger in an automobile from a traffic accident with increase
of the traffic, an air bag has been installed in the recent automobile. For example,
the air bag for a driver contained in a steering wheel is expanded by gas generated
due to shock applied in collision of the automobile and developed in to a vehicle
room. Thus, the air bag protects the driver seated on a driver's seat from collision
against the steering wheel and a front glass. The air bag may also has been contained
in a rear surface side of an instrument panel to protect a passenger seated on
an assistant seat from collision against the instrument panel and the front glass.
Further, in recent years, installing the air bag in a rear surface side of a door
trim to protect the passenger from collision applied from side (door) has been recommended.
The vehicle interior panel such as the instrument panel and the door trim are
constructed by a base member made of a hard resin, a foamed body layer made of
a polyurethane foam etc. and laminated on a surface of the base member, and a skin
made of a polyvinylchloride etc. and laminated on a surface of the foamed body
layer. The interior panel holds shape thereof by rigidity of the base member, increases
smooth feeling by the foamed body layer, and increases surface appearance and further
increases the smooth feeling by the skin.
When the air bag is disposed in the rear surface side of such interior panel,
the interior panel having rigidity is hardly broken to hinder the expansion and
development of the air bag. In view of this, the interior panel is provided with
an opening usually closed or covered by an air bag door and allows the air bag
to develop. When the air bag expands by large shock applied to the automobile by
collision etc., the air bag door is pushed and opened by the air bag for allowing
the air bag to develops into the vehicle room smoothly.
Conventionally, the air bag door is formed separately or independent
from the interior panel, and is fixed to the interior panel by engagement and so
on. According to such separate air bag door construction, the interior panel does
not hinder development of the air bag into the vehicle room. However, in this case,
a boundary line (outer periphery) of the air bag door may appear on the surface
of the interior panel as a relatively wide and deep groove, or a step or height
difference may be formed between the interior panel surface and the air bag door
surface, whereby the surface appearance of the interior panel is deteriorated in
both cases.
On the other hand, if the air bag door is formed integral with the interior panel,
the boundary line of the air bag door does not appear or expose on the surface
of the interior panel to improve the surface appearance thereof. However, such
integral structure may hinder development of the air bag into the vehicle room,
so that connecting strength of the air bag door with the interior panel needs to
be selected as small as possible for an instantaneous development of the air bag
when the shock is applied.
As such interior panels having small connecting strength of the air bag door,
Japanese Patent Publication No. 1-202550 for example discloses a cover body for
an air bag comprising a core layer made of a hard resin and provided with a slit
of H-shape or cross-shape, and a soft skin layer formed on a surface of the core
layer integral therewith.
Also, Japanese Patent Publication No. 5-294196 discloses an air bag containing
cover body comprised of a hard core layer provided with a slit at a rear surface
side thereof, and a soft skin layer.
In these interior panels disclosed in the above Publications, in the usual state
when the shock is not applied, rigidity of the interior panel is secured by the
core layer, and the smooth feeling is obtained by the skin layer. When the shock
is applied, the cover body is torn along the slit on the core layer forming a fragile
portion by the expanding force of the air bag and allows the air bag to develop
into the vehicle room.
However, even when the fragile portion is provided on the core layer so
that part of the core layer defined by the fragile portion forms the door, there
is case where an extensive rigidity of the skin layer hinders development of the
air bag. In view of this, Japanese Patent Publication No. 7-156737 discloses an
air bag structure in which a skin of an air bag door and a skin of an interior
panel are separately formed, and a convex portion and a concave portion provided
on annular bent flanges of the both skins are engaged with each other to form an
integrated skin. This integrated skin is disposed in a mold, followed by an integral
forming of a foamed body layer to the skin. This air bag structure hardly generates
a step or a gap at the boundary portion of the air bag door, and will not cause
problem due to the extension rigidity of the skin. Japanese Patent Publication
No. 11-222089 discloses a skin for an instrument panel comprised of a general portion
and an air bag door portion formed at a part of the general portion and defined
by an annular groove portion. In this skin, the air bag door portion and the general
portion are formed so that a step portion is formed between the surface of the
former and the surface of the latter, and opposing peripheries of the air bag door
portion and the general portion are coincided in a direction parallel to the surface
of the skin.
The groove portion of the skin for the instrument panel is deformed by relative
shift of the air bag door portion and the general portion in the direction orthogonal
to the skin surface to remove the step portion, then is set in the foam mold together
with the resin base member. Then, the foamed body layer is formed by the foam forming
to connect it with the base member and the skin integrally. Thus, the instrument
panel having the air bag door can be produced.
According to the skin for the instrument panel of Japanese Patent Publication
No. 11-222089, the surface appearance of the skin can be improved due to the narrowed
width of the groove portion. Also, the man-hour for forming the skin for the instrument
panel can be reduced since the skin having the air bag door portion can be formed
by single forming process. Further, durability of the mold for the skin increases
since thickness of the convex portion on the mold for forming the groove portion
needs not be thinned extremely.
However, the above Japanese Patent Publication No. 7-156737 and Japanese
Patent Publication No. 11-222089 have following disadvantages. That is, in the
interior panel construction shown in the above JP '737, the skin of the air bag
door and the skin of the interior panel needs to be separately formed, which requires
the separate, two kinds of molds, and increases the manufacturing cost of the skin.
Also, the connecting working between the skin of the air bag door with the skin
of the interior panel increases the required man-hour. Further, to prevent formation
of the step portion and the gap which may be formed at the boundary portion of
the air bag door when the air bag door and the interior panel are connected, the
convex portion and the concave portion formed at the annular flanges of the skins
should have high positional accuracy. To set the tearing condition of the skin
in the expansion of the air bag constant, the convex portion and the concave portion
of the annular flanges should have high shape accuracy. These accuracy requirements
also increase the man-hour.
Also, in the skin for the instrument panel disclosed in the above JP '089,
the groove portion has the depth direction extending orthogonal to the skin surface.
For this reason, if the groove portion is opened in the endurance test or after
long-term use, the deeper part of the groove appears remarkably. Further, the instrument
panel is formed in the condition where the groove portion is deformed, the stress
generated by deformation of the groove portion remains in the skin to cause deformation
of the skin.
SUMMARY OF THE INVENTION
The present invention is made by taking above circumstances into consideration,
and has the first object or purpose to provide a skin comprising a general portion
and a defining portion defined by an annular groove portion and produced integrally
by small man-hour. The surface appearance of the skin is improved by narrowing
width of the groove portion and by removing the step portion between the general
portion and the defined portion, and is not deteriorated by the endurance test
and so on.
The second object of the present invention is to provide an air bag door construction
skin of which has excellent surface appearance, and in which the air bag develops
smoothly and securely.
A skin of the present invention for overcoming the above problem or the subject
matter is comprised of a general portion and a defined portion defined by an annular
groove portion formed at a part of the general portion, and having a parting line
for parting the general portion and the defined portion in the groove portion.
Wherein the general portion has an annular first bent portion formed along the
groove portion to protrude toward a rear surface to be inclined by a predetermined
angle relative to a surface of said general portion; the defined portion has an
annular second bent portion formed along the groove portion to protrude toward
a rear surface to be inclined by a predetermined angle relative to a surface of
the defined portion substantially parallel to the first bent portion; and the surface
of the first bent portion and the surface of the second bent portion are closely
opposed wherein the surface of the general portion and the surface of the defined
portion are flush with each other to form the groove portion therebetween.
A method for manufacturing a skin of the present invention manufactures the skin
including a general portion and a defined portion defined by an annular groove
formed at a part of the general portion. The manufacturing method for the skin
is comprised steps of preparing a mold having an endless and annular wall formed
on a part of a molding surface; forming a skin including an annular groove portion
of substantially U-shape cross-section being formed by the wall of the mold, the
general portion located outside the groove portion, and a defined portion enclosed
by the groove portion, and having a height difference or a step between a surface
of the general portion and a surface of the defined portion; and then removing
the height difference between the surface of the general portion and the surface
of the defined portion by relatively shifting the general portion and the defined
portion after separating the general portion and the defined portion by cutting
a bottom portion of the groove portion.
A manufacturing method for a skin for an air bag door of the present invention
for overcoming the above problem is comprised steps of preparing a mold having
an endless and annular wall formed on a part of a molding surface; forming a skin
including an annular groove portion of substantially U-shape cross-section being
formed by the wall of the mold, a general portion located outside the groove portion,
and a door portion enclosed by the groove portion, and having a height difference
or s step between a surface of the general portion and a surface of the door portion;
and then removing the height difference between the surface of the general portion
and the surface of the door portion by relatively shifting the general portion
and the door portion after separating the general portion and the door portion
by cutting a bottom portion of the groove portion.
An air bag door of the present invention for overcoming the above problem includes
a resin base member, a skin and an intermediate foamed body layer, the skin including
at a part thereof an annular groove portion defining a general portion and a door
portion and being provided a parting line where the skin is separated into the
general portion and the door portion. Wherein said general portion has an annular
end portion having a first bent portion facing with the groove portion, and said
door portion has an annular end portion having a second bent portion facing with
the groove portion; and the first bent portion and the second bent portion are
inwardly inclined by a predetermined angle respectively relative to the surface
of the door portion so that diameters of the first bent portion and the second
bent portion increase towards the surface of the door portion, and are closely
disposed to be buried in the foamed body layer.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a partial cross-sectional view showing an air bag door part of an
instrument panel produced by the first embodiment of the present invention.
FIG. 2 is a partial cross-sectional view showing a powder slush mold used in
the first embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing the powder slush mold on which
a skin is formed in the first embodiment of the present invention.
FIG. 4 is a partial cross-sectional view showing the skin in a cut state in
the first embodiment of the present invention.
FIG. 5 is an explanatory cross-sectional view showing a state where the skin
is disposed on a molding surface of a foam mold in the first embodiment of the
present invention.
FIG. 6 is a partial cross-sectional view showing a powder slush mold used in
the second embodiment of the present invention.
FIG. 7 is a partial cross-sectional view showing a skin produced by the second
embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
In the skin of the present invention, the general portion and the defined portion
are separately formed and can be parted at the parting line formed in the annular
groove portion. The general portion has the annular first bent portion formed along
the groove portion to protrude toward the rear surface to be inclined by the predetermined
angle relative to the surface of the general portion, and the defined portion has
the annular second bent portion formed along the groove portion to protrude toward
the rear surface to be inclined by the determined angle relative to the surface
of the defined parallel to the first bent portion. The surface of the first bent
portion and the surface of the second bent portion are closely opposed to form
the groove portion therebetween, in the state where the surface of the general
portion and the surface of the defined portion are flush with each other.
That is, in the skin of the present invention, the depth direction of the groove
portion is inclined relative to the skin surface. Accordingly, even when the groove
portion of the skin is opened in the endurance test etc., only a inclined surface(s)
of the first bent portion or the second bent portion appears. As a result, the
groove portion is observed to be shallow, and thus surface appearance of the skin
is not deteriorated. In addition, since the general portion and the defined portion
are disposed in the separate state where the surface of the former and the surface
of the latter are flush and the first bent portion of the former and the second
bent portion of the latter are closely contacted, stress has not been generated
in the skin in the forming of the interior panel. Thus, the skin of the present
invention can contribute to produce the interior panel in which no residual stress
has been existed and which has an excellent dimensional accuracy.
Here, the inclined directions of the first bent portion and the second bent
portion of the skin are not restricted. However, when the skin is used for the
instrument panel having the air bag door, the first and second bent portions are
preferably designed to be inclined by the acute angles relative to the surface
of the defined portion in order to prevent a mutual interference in the development
of the air bag.
By the way, in the conventional manufacturing method of the air bag door integrate-type
skin, there is a case where the surface of the air bag door and the surface of
the interior panel are formed integrally and then the door portion is formed by
cutting the integrated skin along the circle. When this manufacturing method is
used, in order to conceal the cut end surface of the skin, an annular groove portion
is preferably formed at a boundary area between the door portion and the general
portion and then it is cut at a bottom portion thereof. However, when the annular
groove portion is formed by a powder slush forming etc., the mold needs to be provided
with an annular wall on a molding surface thereof. This wall should have thickness
larger than the predetermined value to maintain strength of the mold and so on.
As a result, width of the groove portion of the skin increases unnecessarily, causing
surface appearance deterioration of the skin surface.
In view of the above, in the manufacturing method for a skin of the present invention,
a mold having an endless and annular wall formed on a part of a molding surface
is prepared; and a skin including an annular groove portion of substantially U-shape
cross-section being formed by the wall of the mold, a general portion located outside
the groove portion, and a defined portion enclosed by the groove portion, and having
a height difference between a surface of the general portion and a surface of the
defined portion is formed. Then the height difference between the surface of the
general portion and the surface of the defined portion is removed by relatively
shifting the general portion and the defined portion after separating the general
portion and the defined portion by cutting a bottom portion of the groove portion.
portion of substantially U-shape cross-section and formed by the wall of the mold,
the general portion located outside the groove portion, and the defined portion
enclosed by the groove portion, and having a step between a surface of the general
portion and a surface of the defined portion is formed. Then, the step between
the surface of the general portion and the surface of the defined portion is removed
by relatively shifting the general portion and the defined portion after separating
the general portion and the defined portion by cutting a bottom portion of the
groove portion.
Working-out of the wall shape of the mold can narrow width of the groove
portion of the skin even if thickness of the wall is increased, so that not only
strength of the mold can be secured but surface appearance of the skin can be improved.
In the manufacturing method of the skin of the present invention, the wall of
the mold is preferably inclined by the predetermined angle relative to the molding
surface forming one of the general portion and the defined portion of the skin.
Cutting the bottom portion of the groove portion formed by such inclined wall can
form an annular first bent portion bent toward the rear surface by a predetermined
angle at the end portion of the general portion facing with the groove portion,
and can form an annular second bent portion bent toward the rear surface by a predetermined
angle at the end portion of the defined portion facing with the groove portion.
In case where the whole annular wall of the mold is constructed into a truncated
cone shape or a truncated square pyramid shape by adjusting the inclined angle
of the wall, when the step between the surfaces of the general portion and the
defined portion of the skin is removed by relative shift between the general portion
and the defined portion, space existed between the first bent portion and the second
bent portion can be narrowed. As a result, gap appeared at the boundary area between
the general portion and the defined portion can be narrowed, so that width of the
groove portion formed between the first and second bent portions can be extremely
narrowed to increase surface appearance of the skin.
In addition, the whole wall of the mold can be constructed into a rectangular
shape having four sides a pair of wall parts of which opposed to each other are
inclined to be parallel. According to such obstruction, shifting the general portion
or the defined portion in the same direction as the inclined direction of the wall
can remove the step between the surfaces of the general portion and the defined
portion. In this case, working out the wall shape can shorten width of the groove
portion to almost zero in the surface observation, and width of at least one paired
opposing grooves will not be varied by the relative shift between the general portion
and the defined portion.
Hereinafter, embodying modes of the skin and the manufacturing method
thereof according to the present invention will be explained concretely. As the
manufacturing method of the skin, a powder slush method and a vacuum forming can
be used. In the following, manufacturing of the skin by the powder slush forming
method will be explained. It is noted however when the vacuum forming is used,
the mold having the reversed convex/concave on the molding surface to the convex/concave
on the molding surface of the powder slush mold can be sufficiently used.
A height difference between the molding surface part for forming the general
portion
and the molding surface part for forming the defined portion can be determined
in view of the inclined angle of the wall. For example, the whole wall has substantially
a reversed truncated cone shape in which diameter increases toward the molding
surface, the molding surface is formed so that the molding surface part enclosed
by the wall becomes deeper than the molding surface part outside the wall. This
mold can form the skin including the annular groove portion, the general portion
outside the groove portion and the defined portion enclosed by the groove portion,
and having the step between the surfaces of the general portion and the defined
portion. Then the general portion and the defined portion of the skin are separated
by cutting the bottom portion of the groove portion, and are relatively shifted
to remove the step between the surfaces of the general portion and the defined
portion. Consequently, in the relative shift of the general portion and the defined
portion, the first bent portion and the second bent portion are closely contacted
to narrow width of the groove portion forming the boundary area between the general
portion and the define portion. To the contrary, the whole wall has a substantially
truncated cone shape in which diameter decreases toward the molding surface, the
molding surface is formed so that the molding surface part outside the wall becomes
deeper than the molding surface part enclosed by the wall.
In the above manufacturing method of the skin, the inclined angle of the wall
relative to the molding surface is preferably selected larger than 65 degrees.
If the inclined angle of the wall is smaller than 65 degrees, for example, angle
difference between the abuse angle of the wall at side of the general portion and
the acute angle of the wall at side of the defined portion increases. As a result,
the difference of radius of the round portion of the skin formed by the corner
portions of the mold between the inside and outside of the wall increases, so that
surface appearance of the skin is deteriorated.
The surface of the wall of the mold preferably protrudes from a molding surface
(molding surface H) forming the skin having a higher surface, protrudes convexly
following to the molding surface H, and then inverses to continue to a molding
surface (molding surface L) forming the skin having a lower surface.
Such surface shape of the wall can, even if the tip end of the wall has large
thickness, shorten distance between the first bent portion formed by the outer
periphery surface at the tip end portion of the wall and the second bent portion
formed by the inner peripheral surface at the root portion of the wall. Thus, width
of the groove portion of the skin can be narrowed with securing strength of the
wall of the mold.
Here, the skin manufactured by the above manufacturing method can be used as
a skin for various vehicle interior goods such as an air bag, glove box door or
console box door.
In case where the above manufacturing method of the skin is applied to the skin
for the air bag door, the wall of the mold is preferably inclined inwardly relative
to the molding surface part enclosed by the wall by the acute angle, more preferably
by 65 to 85 degrees. Such inwardly inclined wall can form the first bent portion
and the second bent portion of the skin of which the diameters increases toward
the surface side of the door portion, and of which the mutual interference in the
development of the air bag is avoided. Thus, scatter of the skin chip due to interference
between the first and second bent portions can be prevented.
The skin can be formed by resin materials such as polyvinylchloride, thermoplastic
polyurethan or polyolefin.
The bottom portion of the groove portion can be cut by various cutting manners
such as a blade, laser beam or water jet stream. When the blade is used to cut
the groove portion manually, it is guided by the side wall of the wall to cut the
bottom portion smoothly and accurately.
For manufacturing a skin integrated-type air bag door, the skin for the air bag
door produced by the above manufacturing method for example is disposed on one
of molding surfaces of a foam molds so that the surface of the general portion
and the surface of the door portion are flush with each other. Such disposition
of the surface skip can narrow gap between the first bent portion and the second
bent portion, or can bring the first bent portion and the second bent portion into
a closely contacted condition in the surface observation.
On the other hand, on other molding surface of the foam mold, the resin base
member
having been formed into the predetermined shape by the injection-molding etc. is
disposed. In this condition, the foam forming is performed between the skin and
the base member. Thus, the skin integrate-type air bag door in which the skin and
the base member are joined to the foamed body layer can be produced. This manufacturing
method can narrow gap between the first bent portion and the second bent portion
of the skin sufficiently, so that not only leakage of the foaming resin through
the gap is prevented but the surface appearance deterioration of the air bag door
is prevented.
In this manufacturing method of the air bag door, the skin produced by the above
manufacturing method of the skin for the air bag door is preferably used. However,
the skin in which the general portion and the door portion are separately or independently
formed, and which has the first bent portion and the second bent portion inclined
by the same angle can be used. Such skin can have the same advantage as above skin.
The tip end of the first bent portion and the second bent portion is preferably
covered by a tape etc. to prevent leakage of the foaming resin more securely. As
the tape, tapes easily broken or torn in the expansion of the air bag, not scattering
chip thereof is preferably used, and an urethan slub tape is most preferable for
such tape. The urethan slub tape becomes fragile by impregnation and solidification
of a foam urethan resin in the foam-forming to be easily broken. A framework of
the urethan foam can reduce scattering amount of the chip.
When the urethan slub tape is used, it preferably has width of about 10.0 mm
and preferably has small thickness of about 2.0 mm in view of the adhering work
to the first and second bent portions. By taking easiness for breaking of the tape
in the expansion of the air bag into consideration, the porous tape having density
of 0.01 to 0.2 g/cm
3 is desirably used in preference to the fiber series
tape. An adhesive tape having adhesion at both surfaces thereof can be used to
adhere the urethan slub tape to the tip end of the first and second bent portions,
for example. However, when strength of a tape base member of the adhesive tape
may affect bad influence to breaking character thereof, an adhesive agent can be
used for adhesion of the urethan slub tape.
When the skin is disposed on the molding surface of the foam mold, it is preferably
held on the molding surface by an vacuum absorbing and so on. If the skin manufactured
by the manufacturing method of the present invention is used, the whole surface
of the skin can be made flat and the groove portion formed between the general
portion and the defined portion can be narrowed, by merely causing the relative
shift between the first bent portion and the second bent portion due to relative
sliding therebetween. Accordingly, the skin can be positioned on the molding surface
of the foam forming surface easily, and the man-hour necessary for positioning
of the skin can be reduced due to even or smooth surface shape (convex/concave
are not formed).
As resin materials for the resin base member, hard resins such as polypropylene,
polyethylene, nylon, ABS resin, or reinforced resin produced by mixing glass fibers
into polypropylene etc. can be selectively used corresponding to the manufacturing
cost and the forming method. In addition, the resin base member can be produced
by the injection-molding method and so on.
At a part of the resin base member corresponding to the door portion, a fragile
portion or an opening is formed. The fragile portion can be easily broken or torn
in expansion of the air bag. The fragile portion can be formed by a groove, recessed
portion, slit or penetrated hole. The fragile portion can have a square shape,
U-shape, H-shape or cross-shape. The fragile portion of the resin base member and
the boundary area (groove portion) of the skin between the general portion and
the door portion can have same shape to be coincided at the same position, or can
have different shape.
In the air bag door of the present invention, the general portion has an annular
end portion having a first bent portion facing with the groove portion, and the
door portion has an annular end portion having a second bent portion facing with
the groove portion. The first bent portion and the second bent portion are inwardly
inclined by a predetermined angle respectively relative to the surface of the door
portion so that diameters of the first bent portion and the second bent portion
increase towards the surface of the door portion, and are closely disposed to be
buried in the foamed body layer.
Therefore, extremely narrowed width of the groove portion gives excellent
surface appearance of the skin. The first bent portion and the second bent portion
are not connected by the mechanical connection such as engagement of the convex
portion and the concave portion, so they can be separated easily by the expanding
force of the air bag, without hindering development of the air bag and without
scattering the skin chip in the tearing.
The inclined angle of the first bent portion and the second bent portion toward
the door portion is preferably selected more than 65 degrees. If the inclined angles
of the first bent portion and the second bent portion are smaller than 65 degrees,
angle difference between the obtuse angle of the second bent portion and the acute
angle of the first bent portion increases. As a result, the difference of radius
of the round portion of the skin formed by the corner portions of the mold between
the first bent portion and the second bent portion increases, so that surface appearance
of the skin is deteriorated.
The first bent portion and the second bent portion are preferably inclined relative
to the surface of the door portion toward the inner periphery side (radially inwardly)
thereof, more preferably by angle of 65 to 85 degrees. Such inclination of the
first and second bent portion makes opening of the air bag door in the expansion
of the air bag easier for allowing the air bag to develop into the vehicle room.
The skin chip due to interference between the adjacent skins will not be generated.
In summary, according to the skin of the present invention, it has the higher
dimensional accuracy of the skin and has the excellent surface appearance since
deformation of the skin due to stress has not been occurred. If the groove portion
of the skin is opened by in the endurance test etc., the surface appearance is
not deteriorated. According to the manufacturing method for the skin of the present
invention, the skin can be easily formed by single mold to reduce the man-hour
and the manufacturing cost. Further, according to the air bag door of the present
invention, it has the excellent surface appearance since step between the general
portion and the door portion is removed and width of the annular groove portion
located at boundary of the general portion and the door portion is extremely narrowed.
Also, the air back door construction makes the air bag development easier, and
it will not scatter the skin chip in the air bag developing.
Preferred Embodiment of the Invention
Hereinafter, the present invention will be explained concretely based
on embodiments in which the present invention has been applied to an instrument
panel of an automobile and to a skin thereof.
<Embodiment 1>
FIG. 1 shows a partial cross-sectional view showing an air bag door part for
an assistant seat of the instrument panel of this embodiment. This instrument panel
is constructed by a base member
1 made of a resin material, a foamed body
layer
2 laminated on a surface of the base member
1 and made of a
polyurethan foamed body, and a skin
3 laminated on a surface of the foamed
body layer
2.
A fragile portion
10 having an U-shape is formed on the base member
1
(a bottom part of it is shown in FIG. 1), and a hinge portion
11 generally
thin but thicker than the fragile portion
10 is formed between opposed ends
of the fragile portion
10. On a lower surface of the base member
1
a tubular air bag containing portion
12 is formed below the fragile portion
10 to contain an air bag
4 therein.
The skin
3 is constructed by a general portion
30 forming most
of the instrument panel, and a door portion
31 having a circular or rectangular
shape and positioned to face with the air bag containing portion
12, and
an annular endless groove portion
32 is formed at a boundary area between
the general portion
30 and the door portion
31. The general portion
30 and the door portion
31 are separately formed, and therefore the
groove portion
32 has at a bottom portion thereof a parting line where the
general portion
30 and the door portion
31 are to be parted or separated.
Along an end portion of the general portion
30 facing with the groove portion
32 an annular first bent portion
33 is formed to bend toward a rear
surface of the general portion
30 by an obtuse angle relative to a front
surface thereof. Along an end portion of the door portion
31 facing with
the groove portion
32 an annular second bent portion
34 is formed
to bend toward a rear surface of the door portion
31 by an acute angle relative
to a front surface thereof. The first bent portion
33 and the second bent
portion
34 are closely contacted to each other at opposing surfaces, and
a urethan slub tape
6 covering a tip end of them is adhered thereto.
This instrument panel has been produced in the following steps. Firstly, the
base portion
1 is formed by an injection-molding. The fragile portion
10,
the hinge portion
11 and the air bag containing portion
12 are formed
simultaneous with forming of the base member
1.
FIG. 2 is a partial and enlarged cross sectional view showing a molding surface
of a powder slush-mold
5 used to produce the skin
3. On a molding
surface of the power slush mold
5, an annular wall
50 is formed to
define an enclosing and protruded surface
51 and an enclosed and recessed
surface
52 recessed in a thickness direction of the mold
5. The wall
50 has a substantially truncated square pyramid shape the diameter of which
gradually decreases toward a tip end thereof, and is wholly inclined inwardly by
70 degrees relative to the recessed surface
52. The wall
50 has a
thickness of about 1 mm, and the protruded surface
51 and the recessed surface
52 forms a step of about 2.9 mm height.
As thickness of the wall
50 decreases the step height between the protruded
surface
51 and the recessed surface
52 decreases, which is convenient
to reduce wasteful or useless amount of the skin
3 formed by the mold
5.
It is noted however, the wall
50 needs to have thickness more than 1 mm
to secure desired strength of the mold
5.
The skin
3 is powder-slush-formed of a thermoplastic polyurethan powder
by utilizing the powder slush mold
5. The skin
3 is formed, as shown
in FIG. 3, to cover the wall
50, the protruded surface
51 and the
recessed surface
52 of the mold
5. On the skin
3, at position
corresponding to the wall
50 of the mold
5, an annular groove portion
35 having substantially U-shape cross-section is formed.
Next, the skin
3 is demolded from the powder slush mold
5, and
the groove portion
35 is cut at the bottom portion thereof. As shown in
FIG. 4, cutting the groove portion
35 separates the skin
3 into the
door portion
31 and the general portion
30. At the end portion of
the general portion
30 facing with the door portion
31, the annular
first bent portion
33 bent toward the rear surface by the obtuse angle relative
to the surface of the general portion
30 is formed, while at the end portion
of the door portion
31 facing with the first bent portion
33 the
annular second bent portion
34 bent toward the rear surface by the acute
angle relative to the surface of the door portion
31 is formed.
In the skin
3 thus produced, the door portion
31 and the general
portion
30 are relatively shifted so that the surface of the former and
the surface of the latter are flush with each other. Here, the first bent portion
33 and the second bent portion
34 gradually come close to each other
during the relative shift due to their inclinations, and are brought into abutment
at the time when the surface of the door portion
31 and the surface of the
general portion
30 are flush with each other. To a tip of the first bent
portion
33 and the second bent portion
34, the urethan slub tape
6 is adhered to seal them.
Thereafter, as shown in FIG. 5, the skin
3 is subject to a vacuum
absorbing to be absorbed and held on one molding surface of a foam mold
7.
Here, the first bent portion
33 and the second bent portion
34 are
closely contacted to each other, so that the groove
32 formed therebetween
extends lineally and having an extremely small width. The urethan slub tape
6
seals this linear groove
32.
In this condition, the base member
1 formed in advance is disposed on
other
molding surface (not shown) of the foam mold
7, and a foaming urethan resin
is poured into a space formed between the skin
3 and the base member
1.
Thus, the foamed body layer
2 joined with the base member
1 and the
skin
3 integrally is formed. Here, the poured-in foaming urethan resin will
not leak through the groove portion
32 since the first bent portion
33
and the second bent portion
34 are closely contacted to each other and is
covered by the urethan slub tape
6.
In the thus produced instrument panel, on a design surface of the skin
3,
the surface of the general portion
30 and the surface of the door portion
31 flush with each other appear, and there is almost no fear of resin leakage
due to extremely small width of the groove portion
32. In addition, the
first bent portion
33 and the second bent portion
34 are closely
contacted to each other in the separated condition, so any stress resulted from
deformation of them will not occur in the first and second bent portions
33
and
34, whereby deformation of the skin
3 by the stress can be prevented.
For this reason, the skin
3 is excellent in surface appearance and has smooth
feeling. Further, even when the first bent portion
33 and the second bent
portion
34 are opened or spaced at the groove portion
32 in an endurance
test etc., only the surface of the first bent portion
33 inclined by obtuse
angle is exposed but a deeper part of the groove portion
32 inclined by
acute angle is not exposed, so that the surface appearance is not deteriorated.
In FIG. 1, when the air bag
4 contained in the air bag containing portion
12 of the base member
1 expands by shock applied to the automobile,
the base member
1 is torn along the fragile portion
10 and is rocked
toward the foamed body layer
2 about the hinge portion
11 by the
expanding force of the air bag
4. The rocking force of the foamed body layer
2 transmitted from the
3 base member
1 tears and opens the
foamed body layer
2 along a line corresponding to by the fragile portion
10. By the tearing force from the foamed body layer
2, the skin
3
is going to be torn at the groove portion
32.
Here, the foaming urethan resin is impregnated into the urethan slub tape
6
and is solidified therein to make the urethan slub tape
6 extremely fragile.
In addition, the first bent portion
33 and the second bent portion
34
are merely closely contacted. Accordingly, the skin
3 can be easily parted
into the first and second bent portions
33 and
34 at the groove portion
32. In this way, the instrument panel comprised of the base member
1,
the foamed body layer
2 and the skin
3 is torn and opened along the
U-shape line to open the door portion
31 and the part of the base member
1 enclosed by the fragile portion
10 about the hinge portion
11,
thereby allowing the air bag
4 to develop into the vehicle room.
In addition, the first bent portion
33 and the second bent portion
34
of the skin
3 are inclined inwardly relative to the door portion
31
(toward a central portion of the door portion
31) by the angle of 70 degree,
so that the diameter or distance between the first and second bent portions
33
and
34 increases toward the outside (upper surface in FIG. 1). Accordingly,
the first and second bent portions
33 and
34 can guide the expanding
air bag
4 and will not scatter chip of the skin
3 due to non-interference
relation therebetween.
Here, in the instrument panel of this embodiment, the general portion
30
and the door portion
31 of the skin
3 can be formed by the separate
or independent members. Here, the general portion
30 needs to be provided
with a hole portion having size corresponding to the door portion
31.
In this case, the instrument panel can be produced by the same process as the
above instrument panel, except that cutting of the groove
35 of the skin
3 can be omitted by forming the first bent portion
33 and the second
bent portion
34 on the general portion
30 and the door portion
31
in advance. The general portion
30 and the door portion
31 are preferably
produced by the same or common mold, but can be produced by the different or respective molds.
<Embodiment 2>
In the above embodiment 1, thickness of the wall
50 of the powder slush
mold
5 can hardly be thinned smaller 1 mm, and therefore width of the groove
portion
35 of the skin
3 can hardly be narrowed furthermore. However,
according to the following process for the air bag door part, even when the wall
50 of the mold
5 has the thickness larger than 1 mm, the general
portion
30 and the door portion
31 of the skin
3 can be flush
with each other, although some skin
3 is wastefully used.
That is, the embodiment 2 uses a powder slush mold
5 shown in FIG. 6
for forming the skin
3. On a molding surface of the powder slush mold
5,
an annular wall
50 is formed to define at a part of the molding surface
enclosed by the wall
50, and a recessed molding surface
52 (molding
surface H) recessed relative the protruded surface
51 (molding surface L)
is formed. The wall
50 is inclined inwardly by an acute angle relative to
the recessed molding surface
52 (molding surface H), and wholly has a substantially
truncated square pyramid shape in which diameter of the wall
50 decreases
toward a tip end thereof. At the tip end of the wall
50 a ring-like protruded
portion
53 protruded radially inwardly is formed along a periphery of the
recessed molding surface
52 (molding surface H), while at a root portion
of the wall
50 an annular recessed portion
54 recessed radially outwardly
is formed along the periphery of the recessed molding surface
52. Such construction
of the mold
5 can not only shorten distance between the inner peripheral
surface of the recessed portion
54 and the outer peripheral surface of the
wall
50, but can give the wall
50 a substantial thickness thereof
to have the sufficient strength.
Here, the angles determined by the both inner peripheral surfaces of the recessed
portion
54 and the recessed molding surface
52 (molding surface H)
are named θ
1A and θ
1B respectively. In this embodiment,
the both angles θ
1A and θ
1B are selected to be
75 degrees approximately. When the both angles θ
1A and θ
1B
are smaller than 65 degrees, angle difference between the inclined angle
(obtuse angle) of the wall
50 at side of the enclosing molding surface
51
(molding surface L) and the inclined angle (acute angle) of the wall
50
at side of the recessed molding
52 surface (molding surface H) increases.
As a result, the difference of radius of the round portion of the skin
3
formed by the corner portions of the mold
5 between the inside and outside
of the wall
50 increases, so that surface appearance of the skin is deteriorated.
For this reason, the angles θ
1A and θ
1B are preferably
selected to be larger than 65 degrees, but smaller than 85 degrees.
The skin
3 produced by this powder slush mold
5 is, as shown in
FIG. 7, provided with an annular groove portion
35 having a substantially
U-shape cross section at position corresponding to the wall
50 of the mold
5. Cutting the groove portion
35 at a bottom portion thereof can
separate the skin
3 into the general portion
30 and the door portion
31 of which surfaces can be flush with each other by relatively shifting
the body portion
30 and the door portion
31 in the direction shown
by an arrow A.
In the air bag door part of this embodiment, width of the groove portion
35
to be formed between the general portion
30 and the door portion
31
when the surfaces of them are flush can be extremely narrowed, with maintaining
strength of the wall
50.
In addition, since the wall
50 of the mold
5 are inclined inwardly
by the angles of θ
1A and θ
1B at the root portion
thereof, the first bent portion
33 and the second bent portion
34
of the skin
3 formed by the mold
5 are inclined inwardly by approximately
75 degrees relative to the surface of the door portion
31. For this inclination,
diameter or distance between the first and second bent portions
34 and
35
increases toward the front (upper) surface of the door portion
31. Therefore,
in the air bag door construction produced by this skin
3, the air bag can
expand smoothly in the development thereof, and will not scatter chip of the skin
3 due to non-interference relation between the first and second bent portions
33 and
34.
*
