JP2001180427A - Bag for vehicular air bag device, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly expand a bag for a vehicular air bag device in a vertical direction to protect an occupant's abdomen part. SOLUTION: A flow straightening body with upper and lower gas flow blowoff openings is disposed in the bag, and both upper and lower side parts of the bag are folded in an easy-to-expand manner compared with both lateral side parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag for an airbag device for a vehicle and a method for manufacturing the same.

[0002]

2. Description of the Related Art As one kind of a bag for an airbag device for a vehicle, a occupant-side panel and an inflator-side panel are joined at their peripheral edges to be a flexible three-dimensionally inflatable. It is well known that the inflator side panel is formed with an opening portion for mounting an inflator on the inflator side panel (Japanese Patent Publication No. 51-31581). The inflator is attached to such a bag. In the event of a vehicle collision, the gas generated in the inflator instantaneously flows into the bag, inflates the bag and protects the occupant from the impact of the collision.

What is important in a bag for an airbag device for a vehicle is to control the amount of the occupant-side panel protruding toward the occupant and to quickly deploy the occupant in the vertical direction in order to protect the occupant, particularly, the lower abdomen. It is to secure.

In order to control the amount of protrusion of the occupant-side panel, in the above-mentioned known bag for a vehicle airbag device, the occupant-side panel and the inflator-side panel are connected by a tether. When the bag inflates,
The distance between the inflator side panel and the occupant side panel does not extend beyond the length of the tether. However, the effect of the tether on the promotion of vertical deployment cannot be expected much.

On the other hand, a rectifier is disposed inside the bag, and the gas flow generated in the inflator flows vertically,
Attempts have been made to promote the deployment of the bag in the vertical direction, or to improve the folding method of the bag to quickly deploy the bag in the vertical direction. However, neither is sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bag for a vehicle airbag device which can be quickly deployed in a vertical direction to effectively protect an occupant, particularly the lower abdomen, and a method of manufacturing the bag.

[0007]

According to the first aspect of the present invention, there is provided a bag for a vehicle airbag device, wherein the bag is provided inside the bag structure. A straightening body having gas flow outlets at the top and bottom is arranged, and both the upper and lower sides and the left and right sides of the bag structure are folded together, and the former fold is developed as compared to the latter fold. It was easy to do. In this way, the gas flow is blown up and down by the rectifier, whereby the gas flow is intensively applied to the upper and lower sides of the folded bag which is originally easy to deploy. The bag therefore unfolds very quickly in the vertical direction.

According to a second aspect of the present invention, there is provided a bag for an airbag device for a vehicle, wherein the upper and lower sides of the bag structure are first folded in a bellows manner, and then the left and right sides are reversely rolled. It is folded into a ceremony. As described above, bellows folding, which is originally easy to deploy, is performed first, and then reverse roll folding, which is difficult to deploy, is performed, and the folding operation is easy.

According to a third aspect of the present invention, the width of the rectifier is more than three times the diameter of the opening for mounting the inflator head. As a result, a remarkable rectifying effect can be obtained, so that the gas flow can be efficiently blown up and down. Therefore, in combination with the fact that the upper and lower side portions of the bag are easily folded, the vertical deployment can be achieved more quickly.

In the bag for a vehicle airbag device according to any one of claims 1 to 3, the rectifier is formed by joining two sheet pieces attached to the inflator-side panel at their free ends. can do. Claim 4 relates to a method for manufacturing a bag having such a straightener. In this manufacturing method, the following various steps are sequentially performed.

(1) A step of joining the inflator-side panel and the occupant-side panel at their peripheral edges and attaching the two sheet pieces to the inflator-side panel to produce an inverted bag.

(2) A step of inverting the bag by passing the bag through the opening for mounting the inflator.

(3) A step of drawing out the free ends of the two sheet pieces to the outside from the opening for mounting the inflator, and joining these free ends together.

(4) returning the joined free end into the bag.

[0015] According to this method, when the bag is turned over, the straightening body is not completed because the ring-shaped straightening body is not completed, and the joining of the straightening body can be performed relatively easily even after the inversion. .

Claim 5 relates to another method of manufacturing the bag. This involves sequentially performing the following steps.

(1) The inflator-side panel and the occupant-side panel are joined at their peripheral edges, and the two sheet pieces are attached to the inflator-side panel and their free ends are partially joined to each other so that the inverted state is achieved. The process of creating a bag.

(2) The bag is inverted by passing the bag through the opening for mounting the inflator and the free end of the two sheet pieces that are not joined in the step (1). Process.

(3) A step of pulling out the free ends of the two sheet pieces to the outside from the opening for mounting the inflator and joining the portions of these free ends that are not joined in the step (1).

(4) returning the joined free end into the bag.

This method is particularly suitable when the width of the flow regulating body is significantly larger than the diameter of the opening for mounting the inflator. That is, in this case, it is difficult to pull out the two sheet pieces constituting the rectifying body after the reversal according to the method of claim 4, but according to the method of claim 5, after the reversal of the bag, It is only necessary to hold one of the rectifiers partially joined through the opening for mounting the inflator and pull it out, and the entire rectifier can be pulled out, making it easier to complete the rectifier Can be done.

[0022]

1 to 4 show a bag for a vehicle airbag device according to an embodiment of the present invention.

The bag 10 includes an inflator side panel 12.
And an occupant side panel 14. These panels 12 and 14 are both circular and made of a flexible material such as cloth. Both panels 12, 14 are stitched 16 at their peripheral edges to form a bag structure. At the center of the inflator-side panel 12, an opening 18 for mounting the inflator is formed, into which the head 22 of the inflator 20 is inserted. The gas ejected from the inflator 20 inflates the bag 10 three-dimensionally as shown.

Reference numerals 24 and 26 denote strap-shaped tethers made of a flexible material such as cloth, and extend in the horizontal direction to connect the inflator-side panel 12 and the occupant-side panel 14 so that the distance between the panels 12 and 14 is reduced. Restrict it from spreading beyond the length of the tether. Two tethers 24 and 26 are arranged on the diameter of the bag 10 at symmetrical positions on the left and right with respect to the opening 18 for attaching the inflator. Thereby, when the bag 10 is deployed, the bag 10 maintains a uniform flat shape as shown. In this embodiment, the tethers 24 and 26 include a first tether forming cloth 28 sewn to the inflator side panel 12,
Second tether forming cloth 30 sewn to occupant side panel 14
It is composed of The first tether forming cloth 28 includes a circular base 31, two legs 32, 32 extending diametrically outward from two opposing locations on the periphery thereof and having a width smaller than the diameter of the base 31. The base 31 is sewn to the inflator-side panel 12. Similarly, the second tether forming cloth 30 also has a circular base portion 34 and two leg portions 36 extending diametrically outward from two opposing peripheral portions thereof and having a width smaller than the diameter of the base portion 34. , 3
6 and a base 34 is sewn to the occupant side panel 14. Then, the two pairs of legs 32, 32; 36, 36 are sewn together to form the tethers 24, 26.

Reference numeral 40 denotes a rectifier made of a flexible material such as cloth. The flow regulating body 40 is arranged so as to be located at a slight horizontal distance from the inflator-side panel 12 when the bag 10 is inflated. Rectifier 4
0 is considerably wider than the diameter of the opening 18 for mounting the inflator, and covers the opening 18. Rectifier 40
Are formed as a part of the rectifying body forming cloth 42. The rectifying body forming cloth 42 has a circular base portion 44 and two leg portions 4 extending diametrically outward from two opposing locations on the periphery thereof.
6,46. The base 44 is sewn to the inflator-side panel 12 from above the base 31 of the tether forming cloth 28. The free ends of the two legs 46, 46 are sewn to each other to obtain a ring-shaped straightening body 40. In this manner, the rectifier 40 is connected to the inflator-side panel 1 via the two left and right sides 50, 50 facing each other.
2, but upper and lower sides 52, 5 opposed to each other
In No. 2, it is not sewn to the inflator side panel 12. The non-sewn side portions 52 constitute a gas flow outlet.

On the base portion 44 of the rectifying body forming cloth 42, a reinforcing cloth 53 having substantially the same shape as the rectifying body forming cloth 42 is arranged. The reinforcing cloth 53 is sewn to the occupant side panel 12 from above the base 31 of the first tether forming cloth 28 and the base 44 of the straightening body forming cloth 42.

The gas ejected from the inflator 20 collides with the top portion 49 of the flow regulating body 40 and the joints 50, 50 and is deflected, passes through the blowing openings 52, 52 and travels in the vertical direction.

As described above, the tethers 24, 26 are arranged on the left and right sides avoiding the upper and lower outlet openings 52, 52 of the rectifier 40, so that they do not hinder the gas flow blown up and down.

In the illustrated embodiment, the rectifier and the tether are provided separately. Although illustration is omitted, instead of this,
The connecting members 54 similar to the second tether forming cloth 30 shown in FIG. 1 may be connected between the side portions 50, 50 of the flow regulating body 40 and the occupant side panel 14. In this case, the rectifier 4
0 and the connecting member 54 constitute a tether. Conversely, the both sides 50, 50 of the straightening body 40 may be sewn to the inner surfaces of the tethers 24, 26, and the straightening body 40 itself may not be sewn directly to the inflator side panel. Further, the rectifier 40 and the tethers 24, 26 are formed from a single piece of cloth, and both side portions 50, 50 of the rectifier 40 are sewn to the inflator-side panel 12 once, and then the tethers 24, 26 may extend to the occupant side panel 14. In addition, only the tether is attached to the bag body, a separate inflator with a rectifier attached is prepared, and this inflator is attached to the inflator side panel so that the rectifier is arranged in the bag. You may.

The dimensions of the rectifier are 200 to 600 in width.
mm and a length of 200 to 300 mm are preferred. The `` length '' in this case refers to the length of the rectifying body between the sewn portions closest to the periphery when the base of the rectifying body forming cloth is sewn to the inflator-side panel, that is, the bulge swells toward the occupant-side panel. The length of the slack.

The bag of this embodiment is folded as follows and stored in a housing at the center of the steering wheel.

First, as shown in FIG.
The upper and lower sides of the zero are folded on the occupant side panel 14 in a bellows manner. That is, the upper part and the lower part of the bag 10 are folded at a series of points 60a, 60b, 60c, 60d, 60e,. , A plurality of folding pieces 62a, 62b, 62c, 62d,
62e ... are obtained.

Next, the left and right side portions 65 of the folded body 64 thus obtained were folded in a reverse roll type as shown in FIG. 5B.

Here, the "reverse roll type" folding refers to a state in which the side end of the bag is wound around the inflator side panel 12 and folded as shown in FIG. The side terminal of the bag shown in FIG.
The folding method in which the sheet is rolled up and folded on the side of No. 4 is referred to as a forward roll type folding, whereas the folding in the opposite direction is referred to as a "reverse" roll type folding.
More specifically, based on the drawings, when performing reverse roll-type folding on the left and right side portions 65, 65 of the bag as shown in FIG. 5B, the folded body 64 shown in FIG. The left and right side portions 65, 65 are wound in such a manner that the front end 80 is inside, and sequentially folded to form a rolled ball 82. This is the state shown in FIG. Then, from this state, the rolled ball 82 is inverted at the base portion 84 toward the occupant-side panel 14 to obtain a state shown in FIG. 6B. In both the case shown in FIG. 6A and the case shown in FIG.
Both are reverse-roll folds. Actually, it is often folded as shown in FIGS. 6B and 5B from the convenience of storing the folded bag. Reverse roll type folding,
The gas flow generated in the inflator 20 is shown in FIG.
When the occupant-side panel 14 is pressed as shown by the arrow, the ball 82 exists on the side opposite to the pressing direction.
Therefore, the occupant side panel 14 does not easily move forward. On the other hand, in the case of the forward roll type folding, as can be seen from FIG. 7, the rolled ball 81 is pushed forward by pressing the occupant side panel 14 in the direction of the arrow, so that the occupant side The panel 14 easily moves forward. In this way, reverse roll folds are less likely to spread than forward roll folds.

A gas flow is generated from the inflator inside the folded bag. in this case,
Since a bellows type folding method, which is originally easy to deploy compared to the reverse roll type folding method, is employed in the vertical direction in which gas is blown out from the straightening body, the bag is deployed very quickly in the vertical direction. An example of the bag folded in this manner is described below.

As a comparative example, a bag having no straightening body was used. In the folding method, first, as shown in FIG. 8A, both upper and lower sides of the bag were bellowed toward the occupant side panel 14, Next, as shown in FIG. 8 (b), the left and right sides 65 and 65 are also bellow-folded to the occupant side panel 14 side. In this case, since there is no rectifier, the gas flow is not directed intensively in the vertical direction.
In addition, since bellows folds that can be easily deployed at both the upper and lower sides and the left and right sides are adopted, the deployment speed in the vertical direction is not particularly high as compared to the horizontal direction.

FIG. 9 shows the vertical developing speeds of the embodiment and the comparative example. In the case of the example, the width of development in the vertical direction at the beginning of development is significantly larger than that of the comparative example. That is, at 10 seconds after the start of deployment, the former is 500 mm and the latter is 400 mm. Then, both reached the maximum development width in about 14 seconds after the start of the development, and the maximum development width was about 670 mm in the former case and about 510 mm in the latter case. Further, after the rebound, the embodiment draws a gentler curve and converges.

In the above embodiment, a reverse roll type folding is used as a folding method which is relatively difficult to deploy, and a bellows type folding is used as a folding method which is relatively easy to deploy. Alternatively, a reverse roll type fold may be used as a relatively hard-to-deploy fold type, and a forward roll type fold (FIG. 7) may be used as a relatively easy-to-deploy fold type. Further, FIG.
0 (a) shows a normal bellows type folding. On the other hand, FIGS. 10B and 10C show a modification of the bellows-type folding, in which tips 90, 90 are inserted into the bellows from outside or inside, respectively, and held. Therefore, as a folding system that is relatively difficult to unfold, FIG.
(B) and (c), and the one shown in FIG. 10 (a) can be used as a folding method that is relatively easy to deploy. Further, in the above-described embodiment, folding that is easy to expand is performed first, and then folding that is difficult to expand is performed.
The order may be reversed. Further, the bellows type folding, reverse roll type folding and other folding used in the present invention are usually folded toward the occupant side panel, but may be folded toward the inflator side panel.

Next, a method of manufacturing the bag shown in FIGS. 1 to 4 will be described.

In this bag, the sewn portion 16 between the inflator side panel 12 and the occupant side panel 14 and the sewn portions 38 and 38 of the tethers 24 and 26 are inside the bag. After completing the basic form as a bag by suturing the sewn portion, the bag is turned over to obtain the final product shown in FIGS. But,
If the free ends of the two leg portions 46, 46 of the straightening body forming cloth 42 are sewn 48 in advance, the straightening body 40 has a problem that it is difficult to invert the bag.

FIG. 1 shows such a problem and its solution.
The description will be made based on 1 to 22. The bags shown in FIGS. 11 to 22 do not have the reinforcing cloth 53 of the airbag of FIG.
The relationship between the inside and outside of the legs 32 and 36 of the two tether forming cloths 28 and 30 is reversed, and the shape of the straightening body is slightly different, but the other points are the same as those of FIG. Therefore, in FIGS. 11 to 22, basically the same reference numerals as those in FIG. 1 are used.

FIGS. 11 to 13 show the bag in an inverted state. The first tether forming cloth 28 and the straightening body forming cloth 42 are placed on the inflator side panel 12 in this order, and these three members are stitched 29 around the inflator mounting opening 18. Further, a second tether forming cloth 30 is stitched 31 on the occupant side panel 14.

From this state, as shown in FIG.
The free ends of the second tether forming cloths 28 and 30 are sewn on the left and right sides to form tethers 24 and 26. At this time,
The inflator side panel 12 and the occupant side panel 14 must be partially folded into the space defined by the tethers 24,26.

From this state, as shown in FIG.
Central portion 33 between tether forming cloth 30 and occupant side panel 14
To the side of the inflator side panel 12 to open the opening 18.
Invert the bag by passing through it. But,
At this point, the free ends of the straightening body forming cloth 42 are already sewn together, as shown by the one-dot chain line in FIG.
Once the 0 has been completed, the task of flipping the bag is quite cumbersome. That is, although not shown, in the inversion, one of the two opening ends (the front and rear ends of the paper in FIG. 15) 52, 52 of the completed rectifier 40 and the opening 18 of the inflator mounting opening 18 are formed. The portion indicated by 35 (all portions except the straightening body 40 in the bag) must pass from between the peripheral edge and the straightening body 4.
This is because the width of 0 is set larger than the opening 18 for the inflator so as to increase the rectifying effect, and it is difficult to pass through the portion 35 in this way.

To avoid such trouble, FIG.
As shown by the solid line, the free ends of the straightening body forming cloth 42 are not sewn in advance, and the bag is inverted in this state. In this case, since the portion 35 in FIG. 12 may be passed through the inflator mounting opening 18, the work is not so difficult. FIG. 16 shows a state in which the inversion is completed in this manner.

Thereafter, as shown in FIG. 17, the two free ends of the rectifying body forming cloth 42 are pulled out from the opening 18 and are sewn together, and as shown in FIG. Put it. In this way, the bag can be turned over without difficulty.

When the width of the rectifying body 40, that is, the rectifying body forming cloth 42 is extremely large compared to the diameter of the opening 18 for the inflator, the operation is still difficult by the above method. For example, as shown in FIGS. 19 to 21, the width of the rectifying body forming cloth 42 exceeds three times the diameter of the opening 18 for attaching the inflator. This is particularly important in the present invention where it is necessary to blow out the gas flow intensively in the vertical direction. In this case, it is very troublesome to pull out both free ends of the flow regulating member forming cloth 42 by the method shown in FIG. 17 (see FIG. 21). In this case, if the two free ends are partially joined, a part of the straightening body forming cloth 42 is grasped by hand and pulled out, so that the straightening body forming cloth 4 is removed.
It is convenient because the whole of 2 can be pulled out. From this perspective,
The inventor of the present application has conceived a manufacturing method shown in FIGS. That is, before the bag is turned over, the free ends of the flow regulating member forming cloth 42 are brought into contact with each other, and both ends 70,
At 72, suturing 70, 72 is performed. In this way, a central opening 74 is obtained. Then, the portion 35 shown in FIG. 20 is passed through the opening 18 for attaching the inflator and the opening 74, and the bag is inverted. Although not shown, a part of the rectifying body forming cloth 42 whose free ends are partially sewn together is then grasped by hand and pulled out to the outside from the opening 18 for attaching the inflator to the opening 7.
The sewing body 4 is sewn to complete the rectifier 40, which is returned to the inflator.

Instead of initially suturing both ends of the free end, only a suitable portion such as one end or the center of the free end of the straightening body forming cloth 42 may be sewn.

It should be noted that, in claims 4 and 5, FIG.
The configuration shown in FIG. 22 is premised on having the configurations of claims 1 to 3. However, the manufacturing method of the bag of FIGS. 11 to 22 is not necessarily based on the configuration of claims 1 to 3, and can be widely applied to a bag having an opening for inflator attachment and a straightening body. is there.

[0050]

According to the first aspect of the present invention, the gas is blown out from the straightening body in a vertical direction, and the bag is of a folding type which is more easily deployed in the vertical direction than in the horizontal direction. The bag deploys quickly up and down.

The same effect can be obtained with the bag of the second aspect. Further, the folding operation is easy.

In the case of the bag of the third aspect, since the width of the straightening body is significantly larger than the diameter of the opening for mounting the inflator, the straightening effect is remarkable, and furthermore, the speed at which the bag is deployed in the vertical direction. Is even bigger.

According to the method for manufacturing a bag of the fourth aspect, since there is no ring-shaped rectifier when the bag is inverted, the inversion operation is easy.

The method for manufacturing a bag according to the fifth aspect is particularly preferable when the width of the flow regulating body is significantly larger than the diameter of the opening for mounting the inflator. That is, in this case, it is possible to invert the bag by passing the opening for inflator attachment and the unjoined portion in the rectifier, and even after the bag is inverted, even if the rectifier is extremely wide, This can be pulled out to the outside through the opening for mounting the inflator, and the unjoined portion can be joined to easily complete the rectifier.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bag according to an embodiment of the present invention, taken along a horizontal plane and viewed from above. The bag is shown in an inflated state.

FIG. 2 is a sectional view taken along the line II-II of the previous figure. That is, it is viewed from the lateral direction.

FIG. 3 is a view of the previous figure in the direction of the line III-III. That is, it is a front view of the inflator side panel.

FIG. 4 is a partially cutaway perspective view of the bag of this embodiment.

FIG. 5 shows a folded state of the bag of one embodiment;
It is the front view seen from the occupant side panel side. (A) shows the first fold and (b) shows the second fold.

FIG. 6 is a schematic view showing a folding method of a reverse roll type,
(A) shows the state before the inversion to the occupant side panel, (b)
Indicates the state after inversion.

FIG. 7 is a schematic view showing a forward-roll type folding system.

FIG. 8 is a view similar to FIG. 5, illustrating a folded state of Comparative Example 1.

FIG. 9 is a graph comparing the deployment speeds of the bags of Example 1 and Comparative Example 1 in the vertical direction.

FIG. 10 is a schematic view showing various folding methods of a bellows type.

FIG. 11 is a perspective view of the bag in a state before being inverted when viewed from the side of the inflator-side panel in the process of manufacturing the bag of the present invention.

FIG. 12 is a perspective view of the bag of the preceding figure viewed from the side of an occupant side panel.

FIG. 13 is a longitudinal sectional view of the bag of FIG.

FIG. 14 is a longitudinal sectional view showing a first stage of a reversing process of the bag of the preceding figure.

FIG. 15 is a longitudinal sectional view showing the next stage of the bag inverting process.

FIG. 16 is a longitudinal sectional view showing a state in which the inversion of the bag has been completed.

FIG. 17 is a longitudinal sectional view of a state where the straightening body forming cloth is stitched.

FIG. 18 is a longitudinal sectional view showing a state in which the completed straightening body is returned into the bag.

FIG. 19 is a perspective view of a state in which the straightening body forming cloth has a very wide width before inversion of the bag, as viewed from the side of the inflator-side panel.

FIG. 20 is a perspective view of the bag of the preceding figure as viewed from the side of an occupant side panel.

FIG. 21 is a perspective view of the bag of FIG. 19 viewed from the side of the inflator-side panel in an inverted state without sewing the straightening body forming cloth. Tethers are omitted for simplicity.

FIG. 22 is a perspective view of the bag of FIG. 19 in a state where a rectifying body forming cloth is partially stitched.

FIG. 23 trying to flip the bag of the previous figure.
FIG.

[Explanation of symbols]

 Reference Signs List 10 bag 12 inflator side panel 14 occupant side panel 18 opening for inflator 20 inflator 40 rectifier 42 sheet piece

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toru Ozaki 3 Ikayama, Utsugoe, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Inside the Automotive Parts Technology Center of Toyo Tire & Rubber Co., Ltd. (72) Inventor Masahiro Ushio Nishikamo-gun, Aichi Prefecture 3 Ikayama, Utsugoe, Miyoshi-cho Toyo Tire & Rubber Co., Ltd. Auto Parts Technology Center

Claims (5)

[Claims] An occupant-side panel and an inflator-side panel are joined at their peripheral edges to form a three-dimensionally inflatable flexible bag structure, and the inflator-side panel has an opening for mounting an inflator. In a bag for an airbag device for a vehicle, a straightening body having a gas flow blowing opening above and below is disposed inside the bag structure, and both upper and lower sides and both left and right sides of the bag structure are provided. A bag for a vehicle airbag device, wherein the bag is folded, and the former fold is easier to expand than the latter fold. 2. The bag for an airbag device for a vehicle according to claim 1, wherein upper and lower sides of the bag structure are first folded in a bellows manner, and then the left and right sides are inverted. A bag for a vehicle airbag device, which is folded in a roll type. 3. The bag for a vehicle airbag device according to claim 1, wherein the width of the flow regulating body is more than three times a diameter of the opening for mounting an inflator head. Bags for vehicle airbag devices. 4. A bag for an airbag device for a vehicle according to claim 1, wherein said rectifying body is formed of two sheet pieces attached to said inflator-side panel. A method for manufacturing a bag having free ends joined to each other, comprising the following steps. (1) A step of joining the inflator-side panel and the occupant-side panel at their peripheral edges and attaching the two sheet pieces to the inflator-side panel to form a bag in an inverted state. (2) a step of inverting the bag by passing the bag through the opening for mounting the inflator; (3) a step of drawing out the free ends of the two sheet pieces to the outside from the opening for mounting the inflator, and joining these free ends together. (4) returning the joined free end into the bag. 5. A bag for an airbag device for a vehicle according to claim 1, wherein said rectifying member comprises two sheet pieces attached to said inflator-side panel. A method for manufacturing a bag having free ends joined to each other, comprising the following steps. (1) The inflator-side panel and the occupant-side panel are joined at their peripheral edges, and the two sheet pieces are attached to the inflator-side panel, and their free ends are partially joined to create an inverted bag. Process. (2) a step of inverting the bag by passing the bag through the opening for attaching the inflator and a portion of the free ends of the two sheet pieces that are not joined in the step (1). (3) A step of pulling out the free ends of the two sheet pieces from the opening for mounting the inflator to the outside, and joining the portions of these free ends that are not joined in the step (1). (4) returning the joined free end into the bag.