JPH092189A - Manufacture of air bag cover - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of an air bag cover to suppress reduction of a yield and appearance even when the thin section part of a break scheduled part is formed at the thin sink layer of a decorative sheet of three- layer structure arranged on a core surface, and facilitate manufacture. CONSTITUTION: An air bag cover comprises a decorative sheet 12 of three-layer structure heated and softened and formed in a given shape through vacuum molding; and a core 11, into which the decorative sheet 12 is inserted, and formed through injection molding. A thin section part 16e being a break scheduled part broken during expansion of an air bag is formed at a skin layer 13 of the decorative sheet 12. During vacuum molding of a decorative sheet 12, a protrusion part 21b formed on a mold surface 21a of a vacuum molding die 21 is utilized and a curved part 16d approximately in a V-shape in cross section curved from the surface side to the back side is formed along the portion of the break scheduled part of the skin layer 13 and a thin section part 16e is formed at the central part of a stretched part of the curved part 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an air bag cover for an automobile instrument panel, a door trim, a seat back, a steering wheel pad, etc., which covers a folded air bag of an air bag device, and more particularly to an inflatable air bag cover. The present invention relates to a method of manufacturing an airbag cover made of synthetic resin, in which a breakable portion to be broken is arranged to project the airbag at that time, and a decorative sheet having a three-layer structure is arranged on the surface side of the core material.

[0002]

2. Description of the Related Art Conventionally, as an airbag cover of this type, a decorative sheet disposed on the surface of a core material made of a synthetic resin in consideration of the design of the interior member in the peripheral portion. And (see Japanese Utility Model Laid-Open No. 63-22262, etc.).

In order to make the airbag rupture when the airbag is inflated and to project the airbag, the airbag cover is
A thin portion was formed as a portion to be broken. The thin-walled portion to be broken is formed by forming a recess in the airbag cover by melting the airbag cover with a processing jig using high frequency, heat, and ultrasonic waves so as to scrape the airbag cover. JP-A-2-248238 and JP-A-4-1513.
45, JP-A-6-21881, etc.).

The thin portion also needs to be provided on the decorative sheet in order to smoothly break the airbag cover.

In this case, as the decoration sheet, an outer skin layer made of soft vinyl chloride or the like arranged on the front surface side of the decoration sheet, a foamed layer made of expanded polypropylene or the like arranged on the back surface side of the outer skin layer to improve the feeling, A barrier layer made of polypropylene or the like, which is disposed on the back surface side of the foam layer and protects the outer skin layer and the foam layer from heat and injection pressure during injection molding of the core material,
When using a sheet material that is laminated and integrated,
The barrier layer was cut off to form a thin portion by forming a recess so as to scrape the back surface of the outer skin layer.

However, when the outer skin layer has a thickness of about 0.5 mm, which is not the usual thickness of about 1 mm, it is possible to manage the wall thickness when melting to form a thin portion. It is not easy, and it becomes difficult to secure the thickness of the outer skin layer that can be torn or the airbag can be torn when the airbag is inflated, so that many defective products are generated and the yield is reduced. In particular, an airbag cover often has a curved surface due to the requirement of a design shape, and a thin jig is formed on the curved outer layer by operating a processing jig, which promotes the above problems. .

Further, when the thin portion is formed by melting and scraping from the back surface side of the outer skin layer to form the thin portion, only the thin portion is partially heated,
On the surface side of the outer skin layer, the thin-walled portion has a glossy and grainy pattern different from that of the surrounding portion, which may deteriorate the appearance of the airbag cover.

The present invention is intended to solve the above-mentioned problems, and even if a thin portion to be broken is to be formed in a thin outer layer of a three-layered decorative sheet arranged on the surface of a core material. An object of the present invention is to provide a manufacturing method of an airbag cover that can be easily manufactured while suppressing a decrease in yield and appearance.

[0009]

The manufacturing method according to the present invention comprises a decorative sheet which is softened by heating and shaped into a predetermined shape by vacuum forming, and a core material formed by injection molding using the decorative sheet as an insert. The outer cover layer on the front surface side, a foam layer disposed on the rear surface side of the outer cover layer, and the foam sheet disposed on the rear surface side of the foam layer at the time of injection molding of the core material. A barrier layer for protecting the outer skin layer / foaming layer; and the outer skin layer of the decorative sheet, wherein the thin wall portion is formed as a breakable portion to be broken when the airbag is inflated. A method of manufacturing, wherein during the vacuum forming of the decorative sheet, a convex portion provided on a die surface of a vacuum forming die is used, and along the site of the breakable portion of the outer skin layer, the surface is curved from the front surface side to the back surface side. Forming a curved portion having a substantially V-shaped cross section, To push stretched the center of the curved portion,
The thin portion is formed.

[0010]

In the method of manufacturing the airbag cover according to the present invention, when the decorative sheet is vacuum-formed, the convex portion provided on the die surface of the vacuum forming die is used and the outer skin layer is ruptured at a predetermined portion. Forming a curved portion having a substantially V-shaped cross section that curves from the front surface side to the back surface side, and providing a thin portion as a breakable portion to be provided in the outer skin layer of the decorative sheet at the center of the curved portion that is stretched Is.

That is, when the curved portion having a substantially V-shaped cross section is formed by vacuuming, the decorative sheet including the outer skin layer is already softened and is not broken, and the outer skin layer is not broken. The curved portion is formed by being pushed from one side to the back side. Since the curved portion is stretched and formed, a thin portion can be easily formed in the center even if the outer skin layer is thin.

Further, even when the thin-walled portion as the portion to be broken provided on the outer skin layer is formed on the curved surface of the airbag cover, when the decorative sheet is shaped into a curved surface, the vacuum molding die is used. By only providing a convex portion having a constant height along the surface, the curved portion can be formed corresponding to the curved surface, and the thin portion can be easily formed.

Further, since the curved portion to be pushed out is recessed from the surface side, even if the gloss or grain pattern on the surface side of the curved portion changes from other parts, it is difficult to see from the surface side and the appearance deteriorates. Can be suppressed.

Therefore, in the method of manufacturing the airbag cover according to the present invention, even if the thin skin portion of the decorative sheet having the three-layer structure disposed on the surface of the core material is formed with the thin portion to be broken. In addition, it is possible to easily manufacture the device while suppressing a decrease in yield and appearance.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

Air bag cover 10 manufactured in the embodiment.
1 to 3 are formed as a part of an instrument panel (hereinafter abbreviated as instrument panel) 8 of a vehicle, and the instrument panel 8 is composed of an instrument panel body 9 and an airbag cover 10.

The instrument panel body 9 comprises a base material 9a made of a hard synthetic resin such as polypropylene containing a filler,
A decorative sheet 12 described later is provided to extend and a decorative sheet 9b arranged to cover the base material 9a.

The airbag cover 10 is arranged at a position to cover the folded airbag 2 of the airbag device 1, and comprises a core material 11 and a decorative sheet 12 arranged on the front surface side of the core material 11. It is configured.

The airbag device 1 will be described. The airbag device 1 includes a bag-shaped airbag 2 that is folded and stored, and a cylinder type inflator 3 that supplies inflation gas to the airbag 2. , A cylindrical diffuser 4 for diffusing gas from the inflator 3 and flowing into the airbag 2, and a box-shaped case 5 covering the airbag 2, the inflator 3, and the diffuser 4 There is.

Reference numeral 4a is a gas flow hole for diffusing the gas from the inflator 3 into the airbag 2 and inflowing it. Reference numeral 4b is a plurality of bolts projecting from the diffuser 4. These bolts 4b are By fixing the nut 6, the case 5, the airbag 2, and the diffuser 4 are integrated, and the airbag device 1 is attached and fixed to the bracket 7 protruding from the frame of the vehicle.

The side wall of the case 5 has a double structure including an inner panel 5a and an outer panel 5b. The outer panel 5b has a predetermined number of claws 5c that are cut and raised and extend toward the inner panel 5a. Are formed. These claws 5c lock a bracket 11a described later.

The airbag cover 10 is constructed so that the breakable portion 16 is arranged in an "H" shape when viewed from above so that the two door portions 17 and 18 can be opened when the airbag 2 is inflated. There is. It should be noted that the position between the upper and lower ends of the “H” shape of the scheduled breakage portion 16 becomes the hinge portion 19 as the center of rotation when the door portions 17 and 18 are opened.

The core material 11 is a thermoplastic elastomer having compatibility with the base material 9a in order to secure the bending property of the hinge portion 19 without breaking and to secure the bonding force with the base material 9a. Are formed from. In the case of the examples, the base material 9a is formed of polypropylene containing a filler, and examples of the thermoplastic elastomer having compatibility with polypropylene include olefin-based thermoplastic elastomer and styrene-based thermoplastic elastomer. In the case of the examples, the core material 11 is formed of an olefinic thermoplastic elastomer.

Further, the core material 11 has
A bracket 11a having a rectangular tube shape is provided so as to project, and a mounting hole 11b for inserting and locking the claw 5c of the case 5 of the airbag device 1 is formed in the bracket 11a. The bracket 11a includes the planned breakage portion 16 and the door portions 17 and 18,
It is formed to connect the portion of the airbag cover 10 to the case 5 of the airbag device 1 so as to be arranged accurately above the folded airbag 2.

The decorative sheet 12 has a skin layer 13 on the front side.
A foam layer 14 disposed on the back surface side of the outer skin layer 13, and a barrier layer 15 disposed on the back surface side of the foam layer 14 for protecting the outer skin layer 13 and the foam layer 14 during injection molding of the core material 11. And are provided.

In the case of the embodiment, the outer skin layer 13 is made of soft vinyl chloride, the foam layer 14 is made of foam polypropylene, and the barrier layer 15 is made of the same olefinic thermoplastic elastomer as the core material 11. There is. The outer skin layer 13 has a wall thickness of 0.5 mm, the foam layer 14 has a wall thickness of 3.0 mm, and the barrier layer 15 has a wall thickness of 0.7 mm.

A recess 16a is formed in the core material 11 at the portion to be broken 16 and the cut portion 1 is formed in the barrier layer 15.
6b is formed, and the outer skin layer 13 is formed with a curved portion 16d having a substantially V-shaped cross section, which is stretched from the front surface side to the back surface side and has a thin portion 16e arranged in the center. The cutout portion 16b is formed as a part of the recess 16c in which the recess 16a of the core material 11 is extended to the site of the foam layer 14.

The curved portion 16d is continuously formed along the "H" shape of the breakable portion 16, and the concave portions 16a.1 are formed.
The 6c may be formed continuously or intermittently along the "H" shape of the planned breakage portion 16.

The thickness of the thin portion 16e having the minimum thickness in the curved portion 16d is 0.3 mm in the case of the embodiment.

The airbag cover 10 and the instrument panel 8
First, the decorative sheet 9 will be described.
As shown in FIG. 4A, after heating and softening the sheet-shaped decorative sheet 12 including the part b, by the heating heater 20,
As shown in FIG. 4B, it is applied to a vacuum forming die 21 to be vacuum formed and shaped into a predetermined shape to be embedded in the instrument panel 8. At that time, the outer cover layer 13 is stretched by the convex portion 21b formed on the mold surface 21a of the vacuum forming mold 21,
In the outer skin layer 13, a curved portion 16d having a thin portion 16e as a breakable portion is formed.

Then, the decorative sheet 1 in which a molding die for injection molding the base material 9a of the instrument panel body 9 is formed into a predetermined shape.
2. 9 is set and the base material 9a is formed.

After that, the core material 11 of the airbag cover 10
And the core material 11 is formed as shown in FIG. 4C.

After releasing the mold, as shown in D of FIG.
Using the processing horn 22 of the ultrasonic welder, the recess 16
a. 16c is formed, and the bracket 1 of the core material 11 is further formed.
The instrument panel 8 can be manufactured by forming the mounting hole 11b in the la 1a.

As described above, in the method of manufacturing the airbag cover 10 of the embodiment, when the decorative sheet 12 is vacuum formed, the convex portion 21b provided on the die surface 21a of the vacuum forming die 21 is used to make the outer cover layer 13 A curved portion 16d having a substantially V-shaped cross section that is curved from the front surface side to the back surface side is formed at the portion of the breakable portion, and a thin portion 16e as the breakable portion provided in the outer skin layer 13 of the decorative sheet 12 is formed at the curved portion. The decorative sheet 12 including the outer skin layer 13 is already softened by being heated when the curved portion 16d having a substantially V-shaped cross section is formed by evacuation. Therefore, the outer skin layer 13 is pushed from the front surface side to the back surface side without breaking, and the curved portion 16d is formed. Since the curved portion 16d is formed by being stretched, the thin portion 16e is easily formed in the center thereof even if the outer skin layer 13 is thin.

Even when the thin portion 16e, which is a portion to be broken, provided on the outer skin layer 13 is formed on the curved surface of the airbag cover 10, a vacuum is applied when the decorative sheet 12 is shaped into a curved surface. By simply providing the convex portion 21b having a constant height along the mold surface 21a of the molding die 21, the curved portion 16d is formed corresponding to the curved surface, and the thin portion 16e can be easily formed.
Can be formed.

Further, since the curved portion 16d that is pushed out is recessed from the front side, even if the gloss or grain pattern on the front side of the curved portion 16d changes from other parts, it is difficult to see from the front side. It is possible to suppress the deterioration of the appearance, and it is possible to obtain the same effects as those described in the section of the operation and effect of the invention described above.

Since the base material 9a, the core material 11, and the barrier layers 15 of the decorative sheets 9 and 12 have the same kind or compatibility with each other, they are strong without using an adhesive agent separately. Will be joined to.

When forming the recesses 16a and 16c, in addition to using an ultrasonic welder, a heated cutter or a cutter using high frequency is used.
16c may be formed.

By the way, if the instrument panel 8 is manufactured,
After connecting to the airbag device 1 after mounting on the vehicle, the bracket 11a is inserted between the inner panel 5a and the outer panel 5b in the case 5 of the airbag device 1 integrated by using the bolts 4b. And then each nail 5
If c is inserted and locked in the mounting hole 11b, the airbag device 1 is connected to the instrument panel 8, the bracket 7 is fixed to each bolt 4b by the nut 6, and the other end of the bracket 7 is fixed to a frame (not shown). The airbag device 1 can be attached to the vehicle by connecting to the instrument panel 8. It should be noted that when the instrument panel 8 is mounted on the vehicle, a predetermined instrument or the like is provided.

When the gas from the inflator 3 is discharged at a predetermined time, the gas is introduced into the airbag 2 through the gas circulation hole 4a of the diffuser 4, and the airbag 2 pushes up the airbag cover 10. It will be. At that time, the airbag cover 10 is subjected to a tensile load, and stress concentration occurs in the portion of the core material 11 of the expected breakage portion 16 in the portion of the recess 16a provided on the back surface side, and the core material 11 is fractured. In addition, the decorative sheet 12 of the planned breakage portion 16
In the region of (1), the cut portion 16b of the barrier layer 15 is cut, and the outer skin layer 13 has a curved portion 1 having a substantially V-shaped cross section.
A thin portion 16e is formed in the center of 6d, and if a tensile load is applied, stress concentration easily occurs in the thin portion 16e of the curved portion 16d that changes the cross-sectional shape of the outer skin layer 13,
As a result, the thin portion 16e is broken and the portion 16 (16a, 16b, 16e) to be broken between the core material 11 and the decorative sheet 12 is broken.
Will be broken. Therefore, the airbag 2 is to break the scheduled breakage portion 16 of the airbag cover 10 and further open the door portions 17 and 18 around the hinge portion 19 of the airbag cover 10 as a rotation center so as to largely project from the instrument panel 8. Becomes

In the airbag cover 10 manufactured in the embodiment, the case of the airbag device 1 is arranged so that the planned breakage portion 16 and the door portions 17 and 18 can be properly arranged above the folded airbag 2. Bracket 11 to connect with 5
Although the case where a is provided in the core member 11 is shown, if the airbag cover 10 is disposed above the airbag 2 with high accuracy, it is connected to the case 5 like the airbag cover 30 shown in FIG. It is not necessary to provide a bracket.

Further, in the airbag cover 10 manufactured in the embodiment, the cutout portion 16b provided in the barrier layer 15 is formed by injection molding the core material 11 to be integrated with the decorative sheet 12, and then the recess portion 16a of the core material 11 is formed. When forming the processing jig 22
Although the case where the number of processing steps is reduced by simultaneously processing by using the above, the barrier layer of the decorative sheet 12 is previously prepared before the injection molding of the core material 11 that integrates the decorative sheet 12 and the core material 11. The cutout portion 16b may be formed on the portion 15. In that case, after the decorative sheet 12 is vacuum-formed into a predetermined shape, the concave portion 16c is provided, then the core material 11 is molded, and the concave portion 16a is formed in the core material 11. Therefore, the airbag shown in FIG. Like the cover 40, the breakable portion 16
However, the recess 16a provided in the core material 11 and the decorative sheet 1
2 including the cutout portion 16b of the barrier layer 15 and the concave portion 16c that is recessed to the foam layer 14, and the curved portion 16d of the outer skin layer 13.
And will be composed of. By the way, barrier layer 1
When the core material 11 is formed after the cutout portion 16b is provided in the core 5, it is considered that the foam layer 14 and the outer skin layer 13 are damaged by the heat and injection pressure during the molding of the core material 11. , The cutout portion 16b has a narrow width (0.1 to 0.
5 mm), so as to affect the outer surface of the decorative sheet 12,
The foam layer 14 and the outer skin layer 13 are not damaged.

Further, in each of the embodiments, as the manufactured airbag covers 10, 30 and 40, those used for the instrument panel 8 are shown, but they are arranged so as to cover the airbags of airbag devices other than the instrument panel. The present invention can be applied to door trims, seat backs, steering wheel pads, and the like.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an airbag cover manufactured according to an embodiment of the present invention.

FIG. 2 is a perspective view of the airbag cover.

FIG. 3 is a cross-sectional view showing a usage mode of the airbag cover.

FIG. 4 is a diagram showing a manufacturing process of the embodiment.

FIG. 5 is a cross-sectional view showing a usage mode of a modified example of the airbag cover manufactured in the same embodiment.

FIG. 6 is an enlarged cross-sectional view of an airbag cover manufactured in another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Airbag apparatus, 2 ... Airbag, 10/30/40 ... Airbag cover, 11 ... Core material, 12 ... Decorative sheet, 13 ... Skin layer, 14 ... Foam layer, 15 ... Barrier layer, 16 ... Breakage plan Part, 16a ... Recessed part, 16b ... Excised part, 16d ... Curved part, 16e ... Thin part, 21 ... Vacuum forming mold, 21a ... Mold surface, 21b ... Convex part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Fujii 1 Ochiai, Nagachi, Kasuga-cho, Nishikasugai-gun, Aichi Toyoda Gosei Co., Ltd. (72) Inventor Yoshio Yamazaki Yoshio Yamazaki, 1 Ochiai, Nagahata, Kasuga-cho, Nishikasugai-gun, Aichi Toyota Gosei Co., Ltd. Synthetic Co., Ltd.

Claims (1)

[Claims] 1. A decorative sheet, which is softened by heating and shaped into a predetermined shape by vacuum forming, and a core material formed by injection molding using the decorative sheet as an insert, wherein the decorative sheet is a surface side. A skin layer, a foam layer disposed on the back side of the skin layer, and a barrier layer disposed on the back side of the foam layer for protecting the skin layer / foam layer during injection molding of the core material. The outer cover layer of the decorative sheet is a method for manufacturing an airbag cover in which a thin-walled portion as a breakable portion that breaks when the airbag is inflated is formed, wherein the decorative sheet is vacuum-formed. At this time, the convex portion provided on the mold surface of the vacuum forming mold is used to form a curved portion having a substantially V-shaped cross section that curves from the front surface side to the rear surface side along the site of the planned breakage portion of the outer skin layer, At the center of the curved portion that has been stretched, the thin wall A method for manufacturing an airbag cover, which comprises forming a portion.