JP4402159B1 - Manufacturing method of inflator housing for airbag - Google Patents

Abstract

A method for manufacturing an inflator housing for an air bag and an inflator housing for an air bag are provided.
A method of manufacturing a housing is a method of manufacturing a housing in which at least one end is closed, and the outer diameter or outer diameter r of one end of a pipe 3 having both ends open is changed multiple times by different drawing dies. The process of cutting the tip part of the part to be pressed and / or the length of the cylindrical member after the inner peripheral surfaces of the pipes 3 at one end are pressed to each other and gradually reduced. One end is in a closed state through a process of pressing in the direction.
[Selection] Figure 4

Description

  The present invention relates to a method for manufacturing an inflator housing for an airbag and an inflator housing for an airbag.

  Since an inflator housing for an air bag must withstand high pressure generated inside, a high-strength steel plate is used, and advanced technology is required for manufacturing.

  The present applicant has previously proposed the technique described in Patent Document 1 and the technique described in Patent Document 2. That is, the inflator housing for an air bag described in Patent Document 1 is a seamless bottomed tubular member formed by deep drawing from a high-tensile steel plate, and the bottom of the tubular member is thicker than the side surface. Thicken. On the other hand, the hardness of the side surface on the opening side is made higher than that of other side surface portions, or the hardness is increased as the side surface goes to the opening side. Further, the thickness of the side surface of the cylindrical member is made constant on the opening side, and the inner side gradually tapers from the constant portion to the inner side, and the thickness is gradually increased. Patent Document 2 discloses a structure in which one end of a pipe-shaped member is caulked and the opening is closed with a sealing plate.

JP 2007-106330 A JP 2001-212632 A (see FIG. 4)

  The airbag inflator housing described in Patent Document 1 is manufactured by performing deep drawing as described above. There are various lengths and shapes of inflator housings for airbags, and it is considered that the length and shape will be changed in the future. However, in deep drawing, a separate mold must be prepared even if the length of the cylindrical member is changed. It takes days and a lot of cost to make a mold. Further, in manufacturing an inflator housing for an air bag by deep drawing, since the plate-like one is changed to a container having a deep bottom, it is necessary to change the shape significantly, which is troublesome.

  Moreover, in the case of the construction method which crimps one end of the pipe-shaped thing described in patent document 2, another member called a sealing board is needed and the precision control of the sealing board is also needed.

  Therefore, an object of the present invention is to provide a method for manufacturing an inflator housing for an air bag and an inflator housing for an air bag that are easy to process and easy to obtain accuracy.

In order to achieve the above object, an air bag inflator housing manufacturing method of the present invention is an air bag inflator housing manufacturing method in which at least one end is closed. A plurality of punches each having a different shape of the throttle portion, and a rear side portion for making the tip of the cylindrical member a small-diameter cylindrical shape, a small-diameter cylindrical portion, and a portion having the original outer diameter A punch provided with a drawing portion for forming a constricted portion as a curved constricted portion is gradually reduced in multiple times by drawing using the order in which the diameter of the back side portion gradually decreases, and a cylinder at one end after between the inner peripheral surface of the member is in a state mutually pressed, part of the tip portion of the part mutually pressed, the balance through the process of ablation such that conical, mutually pressed subsequently conically And a state of closing one end through the process of pressing in the longitudinal direction and an inward direction of the cylindrical member by using a mold.

Here, when reducing the outside diameter of the one end is provided with a peripheral surface of one end of said cylindrical member, and the outer diameter of the object to be small, the constricted portion of the curved surface having an R value greater than the outside diameter It is preferable to deform the outer peripheral surface .

  Moreover, when performing the process of reducing the outer peripheral diameter of one end by dividing it into a plurality of times, it is preferable to set the outer peripheral diameter in a range of 70% to 95% of the immediately preceding value in one process.

To achieve the above object, an air inflator housing bag of the present invention, the inflator housing for an air bag at least one end is closed, the outside diameter of the one end of the cylindrical member at both ends are opened, the throttle portion shape Is a plurality of punches , each of which has a curved surface portion connecting the back side portion for making the tip of the cylindrical member a small-diameter cylindrical shape, and the small-diameter cylindrical portion and the portion having the original outer peripheral diameter. The punch provided with the constricted portion for forming the constricted portion is gradually reduced in multiple times by drawing using the order in which the diameter of the back side portion gradually decreases, and the inner peripheral surfaces of the cylindrical member at one end are after There was a state mutually pressed, the tip portion of the portion mutually pressing the conical balance portions mutually pressed after being subjected to a process of ablation so as to conical shape, the cylindrical member by using a mold Directionally and is a state of clogging through a process of pressing inwardly, the wall thickness of a portion which is its closed is greater than the thickness of the side portion of the cylindrical member.

Here, it is preferable that the helium leak test result after pressurization of the blocked part is 1 × 10 ⁻⁸ Pa · m ³ / s or less.

  According to the present invention, it is possible to provide a method for manufacturing an inflator housing for an air bag and an inflator housing for an air bag that are easy to process and easy to obtain accuracy.

It is a figure which shows the longitudinal cross-section of the housing which concerns on the 1st Embodiment of this invention. It is the figure which looked at the housing from the arrow A direction of FIG. It is the figure which looked at the housing from the arrow B direction of FIG. It is a figure which shows a mode that a drawing process is given with respect to one opening part of the pipe which concerns on the 1st Embodiment of this invention. It is sectional drawing of the drawing die and pipe used for the 1st drawing process which concerns on the 1st Embodiment of this invention. It is a figure which shows the outer periphery diameter of the pipe which concerns on the 1st Embodiment of this invention, the change rate of the outer periphery diameter before and behind each drawing, the pipe after drawing, and a metal mold | die used. It is sectional drawing of the metal mold | die used for the shaping process of the constriction part of a pipe performed after the drawing process which concerns on the 1st Embodiment of this invention is complete | finished. It is a longitudinal cross-sectional view of the pipe of the state which finished the shaping process of the constriction part of the pipe which concerns on the 1st Embodiment of this invention. It is sectional drawing of the metal mold | die used for the press work of the housing which concerns on the 2nd Embodiment of this invention. It is a figure which shows the longitudinal cross-section of the housing which concerns on the 2nd Embodiment of this invention. It is a figure which shows a mode that drawing processing is given with respect to one opening part of the pipe which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the drawing die and pipe used for the 1st drawing process which concerns on the 2nd Embodiment of this invention. It is a figure which shows the outer periphery diameter of the pipe which concerns on the 2nd Embodiment of this invention, the change rate of the outer periphery diameter before and after each drawing, the pipe after drawing, and a metal mold | die used. It is sectional drawing of the metal mold | die used for the shaping process of the constriction part of a pipe performed after the drawing process which concerns on the 2nd Embodiment of this invention is complete | finished. It is a longitudinal cross-sectional view of the pipe of the state which finished the shaping process of the constriction part of the pipe which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the metal mold | die used for the press work of the housing which concerns on the 2nd Embodiment of this invention. It is a figure which shows the rate of change of the outer periphery diameter r of the pipe at the time of drawing of the housing of the 1st modification which concerns on embodiment of this invention, and the outer periphery diameter r before and behind each drawing. It is a figure which shows the rate of change of the outer periphery diameter r of the pipe at the time of drawing of the housing of the 2nd modification concerning embodiment of this invention, and the outer periphery diameter r before and after each drawing.

  BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a method of manufacturing an inflator housing for an airbag (hereinafter, abbreviated as “housing”) such as an airbag in front of a driver seat and a curtain shield airbag according to an embodiment of the present invention; The description will be given with reference.

(First embodiment)
FIG. 1 shows a longitudinal section of a housing 1 according to a first embodiment of the present invention. The housing 1 is obtained by closing one opening of a pipe (cylindrical member) made of a so-called high tension material and having an outer diameter of 24.6 mm and a wall thickness T1 of 1.6 mm into a hemispherical shape. The center thickness T2 of the closing portion 2 formed by the closing process is 2.0 mm, which is thicker than the thickness T1 of the cylindrical portion 1a. The blocking portion 2 gradually increases from the thickness T1 of the cylindrical portion 1a toward the center, and becomes T2 where the center is the thickest. A radius R1 of the outer periphery of the closing portion 2 is 12.3 mm. The center M1 of the radius R1 is a point where the axial center line of the housing 1 intersects the plane L1 that is the boundary between the closed portion 2 and the cylindrical portion 1a.

  FIG. 2 is a view of the housing 1 as viewed from the direction of arrow A in FIG. A center point 2a appears at the center of the outer peripheral surface of the closing portion 2 of the housing 1, and a plurality of circular encircling lines 2b surrounding the center point 2a appear. FIG. 3 is a view of the housing 1 as seen from the direction of arrow B in FIG. A center point 2c connected to the above-mentioned center point 2a appears at the center of the inner peripheral surface of the closed portion 2. The reason why the center points 2a and 2c and the surrounding line 2b appear will be described later.

Here, the high-tension material (high-tensile steel plate) means a material having a tensile strength of 270 N / mm ² or more, but here, it means a material having a tensile strength of 300 N / mm ² or more. In this embodiment, SAPH590 (tensile strength is 590 N / mm ² ), which is a hot-rolled steel sheet for automobile structure and is a high-strength steel strip, is used.

  The closing process includes a drawing process for drawing one opening of the pipe, a cutting process for cutting a useless part generated through the drawing process, and a pressing process for pressing the cutting part. FIG. 4 is a view showing a state in which the drawing process is performed on one opening of the pipe 3. The outer peripheral surface 4 of the pipe 3 is drawn so that the outer peripheral diameter is gradually reduced in 10 steps.

  The shape of the outer peripheral surface 4A of the pipe 3A that has undergone the first drawing will be described. The outer diameter (hereinafter referred to as “outer diameter r”) of the outer peripheral surface 4 </ b> A, which is the portion of the pipe 3 </ b> A that has been drawn by the first drawing, is 18.5 mm. That is, the outer peripheral diameter r after the first drawing is 75.2% of 24.6 mm, which is the outer diameter before the first drawing. Further, the R value (R value means the curved surface radius) of the curved surface shape of the portion following the curved surface portion of the radius R1 in the constricted portion 5A of the pipe 3A is 18.5 mm like the outer peripheral diameter r of the pipe 3A. It has become. As shown in FIG. 4, the constricted portion 5A has a substantially S-shaped curved surface, and the portion following the cylindrical portion 1a is a spherical surface having a radius R1, and the portion following the spherical portion is in the opposite direction. The shape is bent outward.

  FIG. 5 shows a cross-sectional view of a cylindrical drawing die (punch) 11A used for the first drawing. A portion of the unprocessed pipe 3 that is not inserted into the drawing die 11A is crimped (not shown), and the drawing die 11 is moved in the direction of the arrow by a press device (not shown). When the opening of the pipe 3 hits the inner wall 12 of the drawing die 11A, the pipe 3A after the first drawing is completed.

  In the drawing die 11A, the R value of the curved surface insertion side portion 13a of the narrowed portion 13 for narrowing the pipe 3 is 12.3 mm, which is the same as the radius R1, and the R value of the curved back side portion 13b is the outer diameter r of the pipe 3A. And 18.5 mm. The shapes of the curved surface insertion side portion 13a and the curved surface rear side portion 13b are the same as those of the constricted portion 5A of the pipe 3A. A distal end side portion 14 having a circular hole with a diameter of 24.6 mm is arranged on the further distal end side of the curved surface insertion side portion 13a, and a rear side having a circular hole with a diameter of 18.5 mm is disposed further behind the curved surface rear side portion 13b. Part 15 is arranged. A through hole 16 for venting air when the mold 11A is used is provided in the back side portion 15 in the center of the cylindrical mold 11A and in the axial direction.

  FIG. 4 shows the outer peripheral surfaces 4B to 4K of the pipes 3B to 3K after the second to tenth drawing processes. The second drawing from the pipe 3A to the pipe 3B by the drawing die 11B, the third drawing from the pipe 3B to the pipe 3C by the drawing die 11C, and the fourth from the pipe 3C to the pipe 3D by the drawing die 11D Drawing, the fifth drawing from the pipe 3D to the pipe 3E by the drawing die 11E, the sixth drawing from the pipe 3E to the pipe 3F by the drawing die 11F, the pipe 3F to the pipe 3G by the drawing die 11G 7th drawing process, 8th drawing process from pipe 3G to pipe 3H by drawing mold 11H, 9th drawing process from pipe 3H to pipe 3J by drawing mold 11J, and drawing mold 11K The tenth drawing process from the pipe 3J to the pipe 3K is performed in the same manner as the first drawing process.

  For example, the R values of the narrowed portions 5A to 5K after each drawing and the curved back side portion 13b are set to the same value as the outer peripheral diameter r of the pipes 3A to 3K at the time of the processing. In order to change the R value of the curved back side portion 13b each time, the molds 11A to 11K (hereinafter collectively referred to as “mold 11”) are different in shape (not shown) in each drawing process. .

  FIG. 6 is a diagram showing the outer diameter of the pipe 3, the outer diameter r of the pipes 3A to 3K, the rate of change of the outer diameter r before and after each processing, the pipe after drawing, and the mold used. In FIG. 6, the diameter of the outer periphery of the pipe 3 is shown in the “outer diameter” column. In the example shown in FIG. 6, the outer peripheral diameter is 75.2 to 85.7% with respect to the immediately preceding outer peripheral diameter, and is reduced in the range of 14.3 to 24.8%. Moreover, it is 80.0 to 85.7% after the 2nd time, and is contained in the range of 80 to 86%.

  FIG. 7 shows a cross-sectional view of a mold 11L used for shaping the constricted portion 5K of the pipe 3K, which is performed after ten times of drawing. In this mold 11L, a portion corresponding to the curved back side 13b of the mold 11A is eliminated, and a sharp portion 22 is formed, and only the curved insertion side 13a remains. A portion of the pipe 3K that is not inserted into the mold 11L is crimped (not shown), and the mold 11L is moved in the direction of the arrow by a press device (not shown). And the protrusion part P used as the part to press which the outer peripheral diameter r of the pipe 3K is 4 mm is inserted in the hole 23 of 11 L of metal mold | dies. The hole 23 is a portion surrounded by the back side 15 described above.

  Along with this insertion, the pointed portion 22 hits the base of the protruding portion P (the portion having an R value of 4 mm). As a result, the portion having the R value of 4 mm is deformed and is not curved, and the protruding portion P becomes the pressing portion 26. And the pipe 3L (refer FIG. 6, FIG. 8) whose drawing process parts other than the protrusion part P are spherical is obtained. When the diameter of the through hole 16 is 4 mm, the hole portion 23 has the same diameter as the through hole 16, and thus has a shape that cannot be distinguished from the through hole 16.

  FIG. 8 is a longitudinal sectional view of the pipe 3L in a state in which the shaping process of the constricted portion 5K of the pipe 3K is completed. Since the outer diameter r of the pipe 3 is 24.6 mm and the wall thickness T1 is 1.6 mm, the cross-sectional area of the metal portion of the cylindrical portion 1a of the pipe 3L is 115.6 square millimeters. On the other hand, since the outer diameter r of the pipe 3L is 4 mm, the area of the cross section of the protruding portion P is 12.6 square millimeters. For this reason, the inner peripheral surfaces of the cylindrical members are in a pressed state from the fourth drawing process theoretically. Therefore, the meat on the tip side of the pipe 3 is used to increase the length of the protruding portion P, and is used to increase the thickness of the blocking portion 2. Moreover, as shown in FIG. 8, the inner peripheral surfaces of the projecting portion P of the pipe 3L are pressed against each other, and the portion is closed. Moreover, the area of 115.6 square millimeters of a cross section is made small gradually by the drawing process of a total of 10 times with the metal mold | die 11A and the metal mold | die substantially the same as the metal mold | die 11A. As a result, the surplus metal is used to increase the thickness of the drawn portion of the pipe 3L. In this way, the thickness of the closing portion 2 gradually increases as the thickness T1 of the cylindrical portion 1a goes toward the center, and becomes the thickest T2 at the center.

  The pressing portion 26 protruding above the pipe 3L shown in FIG. 8 is cut (removed) along the dotted line, and the remaining portion is processed into a conical shape. Thereafter, the pipe 3L including the pressing portion 26 having the remaining protruding portion P is formed into a mold 11M shown in FIG. 9 and a cylindrical shape with a diameter of 24.6 mm which is placed inside the pipe 3L and the tip is a hemispherical surface along the inner peripheral portion. Punched from both sides with a metal mold (receiving die, not shown) (pressing process). As a result, the pipe 3L becomes the pipe 3M, that is, the housing 1 shown in FIG. 1, and the manufacturing process of the housing 1 is completed. In addition, the front-end | tip part of the front end side part 14 of the metal mold | die 11 is made into the curved surface shape where an internal diameter becomes large, so that it goes to the front-end | tip for making it easy to enter the pipes 3, 3A-3M.

  The housing 1 has center points 2a and 2c which are minute dot-like traces at a portion where the inner peripheral surfaces of the pipe 3 are pressed. Moreover, in the process which planarizes the press part 26 which is the last process, the trace of the press part 26 remains as the smallest surrounding line 2b among the surrounding lines 2b. Moreover, a part of the trace of the boundary part of the front end side part 14 and the curved surface insertion side part 13a in each processing remains as another surrounding line 2b. When the mold 11L is used, the pressing portion 31 may be flattened or spherical with only the mold 11M without using the other mold that sandwiches the pipe 3L. Moreover, you may make it cut off the protrusion part P along a dashed-dotted line instead of a dotted line. In this case, the shaping process with the metal mold 11M becomes unnecessary. Further, when the surface of the blocking portion 2 is polished or the number of drawing processes is increased, the surrounding line 2b becomes inconspicuous or disappears.

(Second Embodiment)
FIG. 10 shows a longitudinal section of the housing 31 according to the second embodiment of the present invention. The housing 31 is made of the same high-tension material as the housing 1 in the first embodiment, and has one opening of a pipe (cylindrical member) having an outer diameter of 24.6 mm and a wall thickness T3 of 1.6 mm in a planar shape. It is obtained by closing. The thickness T4 at the center of the closing portion 32 formed by the closing process is 2.0 mm, which is thicker than the thickness T3 of the cylindrical portion 31a. The blocking portion 32 is T4 having the thickest central portion.

  As in the first embodiment, the closing process is a drawing process for drawing one opening of a pipe, a cutting process for cutting a useless part generated through the drawing process, and a pressing for pressing the cutting part. It consists of processing. FIG. 11 is a diagram illustrating a state in which drawing processing is performed on one opening of the pipe 33. The outer peripheral surface 34 of the pipe 33 is drawn so that the outer peripheral diameter is gradually reduced in nine steps.

  The shape of the outer peripheral surface 34A of the pipe 33A that has been subjected to the first drawing will be described. The outer diameter r of the outer circumferential surface 34A, which is the portion of the pipe 33A that has been drawn by the first drawing, is 18.5 mm. That is, the outer peripheral diameter r after the first drawing is 75.2% of 24.6 mm, which is the outer diameter before the first drawing. Further, the R value of the curved surface shape close to the opening side (upper side in FIG. 11) of the constricted portion 35A of the pipe 33A is 18.75 mm, like the outer peripheral diameter r of the pipe 33A. As shown in FIG. 11, the constricted portion 35A has a substantially S-shaped curved surface shape, similar to the pipe 3A according to the first embodiment.

  FIG. 12 shows a cross-sectional view of a columnar drawing die (punch) 41A used for the first drawing. A portion of the unprocessed pipe 33 that is not inserted into the drawing die 41A is crimped (not shown), and the drawing die 41 is moved in the direction of the arrow by a press device (not shown). When the opening of the pipe 33 hits the inner wall 42 of the drawing die 41, the pipe 33A after the first drawing is completed.

  In the drawing die 41A, the insertion side portion 43a of the restriction portion 43 for restricting the pipe 33 is linear, and its inlet is 24.6 mm like the outer peripheral diameter r of the pipe 33, and the curved back side following the insertion side portion 43a. The R value of the portion 43b is 18.5 mm, similar to the outer peripheral diameter r of the pipe 33A. The inner diameter of the tip side portion 44 is 24.6 mm, similar to the outer diameter r of the pipe 33, and the inner diameter of the inner side portion 45 is 18.5 mm, similar to the outer diameter r of the narrowed portion of the pipe 33A. is there. The insertion side portion 43a may be a curved surface instead of a linear shape. In that case, the R value of the insertion portion 43a is preferably the same as the radius R2 of the curved outer periphery of the closing portion 32 of the housing 31. As shown in FIG. 10, the center M2 of the radius R2 is an intersection of a plane L2 serving as a boundary between the cylindrical portion 31a and the blocking portion 32 and a plane L3 serving as a boundary between the blocking portion 32a and the curved surface portion 32b.

  FIG. 11 shows the outer peripheral surfaces 34B to 34J of the pipes 33B to 33J after the second to tenth drawing. The second drawing from the pipe 33A to the pipe 33B by the drawing die 41B, the third drawing from the pipe 33B to the pipe 33C by the drawing die 41C, and the fourth from the pipe 33C to the pipe 33D by the drawing die 41D Drawing, the fifth drawing from the pipe 33D to the pipe 33E by the drawing die 41E, the sixth drawing from the pipe 33E to the pipe 33F by the drawing die 41F, the pipe 33F to the pipe 33G by the drawing die 41G The seventh drawing process, the eighth drawing process from the pipe 33G to the pipe 33H by the drawing mold 41H, and the ninth drawing process from the pipe 33H to the pipe 33J by the drawing mold 41J are the first drawing process. The same as processing.

  For example, the R value of the narrowed portion 35A to 35J after each drawing and the R-value of the curved back side portion 43b are the same as the outer peripheral diameter r of the narrowed portion of the pipes 33A to 33J during the machining. Value. In order to change the R value of the curved back side portion 43b each time, the molds 41A to 41J (hereinafter collectively referred to as “mold 41”) have different shapes (not shown) in each drawing process. .

  FIG. 13 is a diagram showing the outer diameter of the pipe 33 and the outer diameter r of the pipes 33A to 33J, the rate of change of the outer diameter r before and after each processing, the pipe after drawing, and the mold used. In FIG. 13, the diameter of the outer periphery of the pipe 33 is shown in the “outer diameter” column. In the example shown in FIG. 13, the deformation rate is 75.2 to 85.8%. Moreover, it is 80.0 to 85.8% after the 2nd time, and is contained in the range of 80 to 86%.

  FIG. 14 shows a cross-sectional view of a mold 41K used for shaping the constricted portion 35J of the pipe 33J, which is performed after nine drawing operations have been completed. In this mold 41K, there is no portion corresponding to the curved back side portion 43b of the mold 41A, the curved portion 52 having an R value of 0.03 mm is left, and only the insertion side portion 43a having a curved shape remains. Yes. A portion of the pipe 33J that is not inserted into the die 41K is crimped (not shown), and the die 41K is moved in the direction of the arrow by a press device (not shown). And the protrusion part Q used as the part which the inner peripheral surfaces whose outer peripheral diameter r of the pipe 33J is 4.75 mm presses is inserted in the hole 53 of the metal mold | die 41K. The hole 53 is a portion surrounded by the back side 45 described above.

  Along with this insertion, the bent portion 52 hits the root of the protruding portion Q (the portion having an R value of 4.75 mm). Then, the portion having the R value of 4.75 mm is deformed to form a curved surface shape having a small R value, and the protruding portion Q becomes the pressing portion 56. And the pipe 43K (refer FIG. 13, FIG. 15) from which the drawing process parts other than the protrusion part Q become the obstruction | occlusion part 32 from the plane part 32a and the curved surface part 32b is obtained.

  FIG. 15 is a longitudinal sectional view of the pipe 33K in a state in which the shaping process of the constricted portion 35J of the pipe 33J is completed. Since the outer diameter r of the pipe 33 is 24.6 mm and the thickness T3 is 1.6 mm, the area of the cross section of the metal portion of the cylindrical portion 31a of the pipe 33K is 115.6 square millimeters. On the other hand, in the third time, the outer diameter r is 12.6 mm, and in the fourth time, the outer diameter r is 10.6 mm. For this reason, the inner peripheral surfaces of the cylindrical members are in a pressed state from the fourth drawing process theoretically. Since the outer diameter r of the pipe 33K is 4.75 mm, the area of the cross section of the protruding portion Q is 17.7 square millimeters. Accordingly, the meat on the tip side of the pipe 33 is used to increase the length of the protruding portion Q, and is used to increase the thickness of the closing portion 32. Further, as shown in FIG. 15, the inner peripheral surfaces of the protruding portion Q of the pipe 33K are pressed against each other, and the portion is closed. In addition, the area of 115.6 square millimeters of the cross section is gradually reduced by drawing a total of nine times using the mold 41A and the mold substantially the same as the mold 41A. As a result, the excess metal is used to increase the thickness of the drawn portion of the pipe 33K. In this way, the thickness of the closing portion 32 is a thickness T4 that is thicker than the thickness T3 of the cylindrical portion 31a.

  The pressing portion 56 protruding above the pipe 33K shown in FIG. 15 is cut along the dotted line, and the remaining portion is processed into a conical shape. After that, the pipe 33K including the pressing portion 56 having the remaining protruding portion Q is a mold 41L shown in FIG. 16, and a mold having a cylindrical shape with a diameter of 24.6 mm and a flat tip at the inside of the pipe 33K. Punch from both sides with (receiving die, not shown). As a result, the pipe 33K becomes the pipe 33L, that is, the housing 31 shown in FIG. 10, and the manufacturing process of the housing 31 is completed. A distal end side portion 44 having a circular hole with a diameter of 24.6 mm is arranged on the further distal end side of the insertion side portion 43 a, and a far side portion having a circular hole with a diameter of 18.5 mm is disposed further behind the curved surface rear side portion 43 b. 45 is arranged.

  When using the mold 41L, the pressing portion 56 may be flattened only by the mold 41L without using the other mold sandwiching the pipe 33K. Moreover, you may make it cut off the protrusion part Q along a dashed-dotted line instead of a dotted line. In this case, the shaping process with the mold 41L becomes unnecessary.

(Main effects obtained by the embodiment of the present invention)
Since the housings 1 and 31 according to the first and second embodiments of the present invention undergo a process in which the inner peripheral surfaces on the one end side of the pipes 3 and 33 are pressed against each other in the manufacture thereof, they are closed. The parts 2 and 32 can be reliably closed. Further, in the manufacturing method of the housings 1 and 31, the degree of change in the shape of the workpiece by each mold in the closing process is significantly smaller than that of the deep drawing process, and the processing time is less. In addition, since the housings 1 and 31 are cut off at the tip portions of the pressing portions 26 and 56 and are then sandwiched between two molds, the dimensional accuracy such as the thicknesses T2 and T4 of the closing portions 2 and 32 is improved. Easy to put out. In addition, since the pressing portions 26 and 56 are further pressed after excision, the degree of occlusion at the portion connecting the center points 2a and 2c is increased. Furthermore, the housings 1 and 31 can both withstand the impact of operating the airbag inflator. This impact resistance is equal to or greater than that of conventional deep drawing.

  Further, in the manufacture of the housings 1 and 31, when one end of the pipes 3 and 33 is drawn, the constricted portions 5A to 5K and 35A to 35J after the drawing are formed on the curved back side portions 13b and 43b. The R value is the same value as the outer diameter r of the pipes 3A to 3K and 33A to 33J after the processing. Therefore, the amount of drawing in one drawing process is appropriate. Therefore, even the high tension pipes 3 and 33 can be closed without buckling. In addition, drawing by cold working is possible, dimensional changes due to heating during processing can be avoided, and the housings 1 and 31 with better dimensional accuracy can be manufactured.

  In addition, the housings 1 and 31 have a change rate of the outer peripheral diameter r before and after each drawing process in the manufacture of 75% to 86% (see FIGS. 6 and 15). Therefore, the amount of drawing in each drawing process is appropriate. Therefore, even the high tension pipes 3 and 33 can be closed without buckling. In addition, drawing by cold working is possible, dimensional changes due to heating during processing can be avoided, and the housings 1 and 31 with better dimensional accuracy can be manufactured.

  Further, the housings 1 and 31 have the thicknesses T2 and T4 at the centers of the closed portions 2 and 32 larger than the thicknesses T1 and T3 of the cylindrical portions 1a and 31a. The cylindrical portions 1a and 31a are made thicker from the thicknesses T2 and T4 toward the center. Therefore, it can be set as the housings 1 and 31 with the higher impact resistance of a process part.

  Further, in the manufacturing method of the housings 1 and 31, only the portions to be closed are processed, and the side portions and the like of the housings 1 and 31 are not processed. Therefore, the housings 1 and 31 can be manufactured using the same molds 11 and 41 for the pipes 3 and 33 having different lengths or thicknesses T1 and T3. Further, the manufacturing method can be applied to a bent pipe to perform a closing process. Since such an effect is difficult to obtain by the conventional deep drawing process, the manufacturing method of the housings 1 and 31 is advantageous in manufacturing housings of various shapes at low cost.

The housings 1 and 31 were subjected to a helium leak test for the closed portions 2 and 32. The result was 1 × 10 ⁻⁸ Pa · m ³ / s or less, and it was found that a very good closed state was obtained. This test condition is that before and after pressurization with the helium gas at 30 MPa for 3 seconds with respect to the closed portions 2 and 32, how many helium atoms pass per second after making a vacuum of 0.5 Pa around the housing 1 and 31. This is measured using a helium leak detector (Alcatel ASM180T). In the housing having a diameter of 20 mm, the pressure was 1.5 × 10 ⁻⁹ Pa · m ³ / s before pressurization and 2 × 10 ⁻⁹ Pa · m ³ / s after pressurization. Further, in the housing having a diameter of 25 mm, the pressure was 3 × 10 ⁻⁹ Pa · m ³ / s before pressurization and 6 × 10 ⁻⁹ Pa · m ³ / s after pressurization. There were no housings 1, 31 exceeding 1 × 10 ⁻⁸ Pa · m ³ / s.

(Other forms)
Although the housings 1 and 31 and the manufacturing method thereof in the embodiment of the present invention have been described above, various modifications can be made without departing from the gist of the present invention.

  The manufacturing method of the housings 1 and 31 according to the embodiment of the present invention is the manufacturing method of the housings 1 and 31 in which at least one end is closed. The outer peripheral diameter r is gradually reduced by a plurality of different drawing dies, and the inner peripheral surfaces of the pipes 3, 33 at one end are pressed against each other, and then the pressing portions 26, 56 are cut off. Through the process and the process of pressing the remaining cut portions 26 and 56 in the length direction of the cylindrical members 1 and 31, one end is made the closed portions 2 and 32. However, the pressing portions 26 and 56 may be pressed in the length direction of the pipes 3 and 33 without cutting the pressing portions 26 and 56. Such pressing also makes it easy to obtain dimensional accuracy such as the thicknesses T2 and T4 of the blocking portions 2 and 32.

  Further, only the pressing portions 26 and 56 may be excised and the pressing process may not be performed. In addition, the excision of the pressing portions 26 and 56 is not necessarily required, and the pressing portions 26 and 56 can be left as they are. Further, neither cutting nor pressing may be performed. Further, the manufacturing method may be applied to the housings 1 and 31 using a housing in which the other open ends at both ends are closed or one end is closed. Moreover, you may use this manufacturing method for the opening part of both ends. Moreover, in each embodiment, the front-end | tip of the press parts 26 and 56 is cut (removed), and it is set as the cone shape, However, A front-end | tip is excised flatly or it excises so that it may become parallel to the curved surface shape of the obstruction | occlusion part 2. (Cutting) may be performed.

  9 and 16 show the molds 11M and 41L to which the above-described pressing is performed. Here, at the time of this pressing, the closing portions 2 and 32 may be compressed by pressing from the back side of the closing portions 2 and 32 using a mandrel in the direction opposite to the above pressing direction. Conversely, pressing may be performed only with the molds 11M and 41L.

  Further, in the manufacturing method of the housings 1, 31, when performing drawing processing to reduce the outer peripheral diameter r at one end, the curved shape of the outer peripheral surface at one end of the pipes 3, 33 is the same as the outer peripheral diameter r to be reduced. It is deformed into a curved surface shape having the R value. However, such a drawing method is not necessarily required. The curved shape at one end of the pipes 3 and 33 may be deformed into a shape having an R value larger or smaller than the outer peripheral diameter r to be reduced. If the curved shape at one end of each of the pipes 3 and 33 is deformed to a shape having an R value smaller than the outer peripheral diameter r to be reduced, the number of drawing processes can be reduced. Further, it is preferable to deform the curved shape of one end of the pipes 3 and 33 into a shape having an R value larger than the outer peripheral diameter r to be reduced because buckling during drawing can be further suppressed.

  Further, in the manufacturing method of the housings 1 and 31, when performing the drawing process in which the outer peripheral diameter r at one end is reduced in several times, the outer peripheral diameter r is reduced from 75% to 86% by one drawing process. It is small. However, such a drawing method is not necessarily required. The ratio of reducing the outer peripheral diameter r in one drawing process is preferably in the range of 70% to 95%. By setting it to 70% or more, buckling during drawing can be further suppressed. Moreover, the frequency | count of a drawing process can be reduced by setting it as 95% or less. Considering this, the range of 70% to 86% is more preferable.

  The housing 1 has center points 2a and 2c and a circular encircling line 2b surrounding the center points 2a and 2c at the center of the outer peripheral surface of the bottom of the bottomed cylindrical shape. As described above, when the center points 2a and 2c appear in the center, the center position can be known, and it is easy to increase the accuracy of incorporation and incorporation when incorporating other components into the housing 1 or incorporating other components into the housing 1. Further, when the encircling line 2b appears, it becomes easier to obtain the accuracy. However, the center points 2a and 2c and the circular encircling line 2b surrounding them are not essential components and can be omitted. In the housing 31 as well, center points corresponding to the center points 2a and 2c appear. Enclosures corresponding to the encircling line 2b may also appear, but the number is very small.

  Various dimensions such as the thicknesses T1 and T3 of the side portions of the pipes 3 and 33 and the diameter of the outer periphery of the pipes 3 and 33 can be appropriately changed depending on the specifications of the housings 1 and 31. For example, the configuration of the housing 1 according to the first embodiment is the same as that of the first embodiment except that the outer peripheral diameter r of the pipes 3 and 33 is 25.2 mm and the conditions of each drawing process are slightly different from those of the first embodiment. And the housing of the 1st modification with the same manufacturing method can be manufactured. FIG. 17 is a diagram showing the outer peripheral diameter r of the pipe when the drawing is performed using such a pipe and the change rate of the outer peripheral diameter r before and after each drawing.

  In addition, the outer peripheral diameter r of the pipe is 18 mm, the thickness corresponding to the wall thickness T3 is 2 mm, the number of times of drawing is seven times, and the conditions of each drawing are slightly second. A housing of the second modification example having the same configuration and manufacturing method as those of the housing 31 according to the second embodiment can be manufactured except that the configuration is different from that of the first embodiment. FIG. 18 is a diagram illustrating the outer peripheral diameter r of the pipe when the drawing is performed using such a pipe, and the change rate of the outer peripheral diameter r before and after each drawing.

  Moreover, in the manufacturing method of the housings 1 and 31, the shaping of the constricted portions 5K and 35J of the pipes 3K and 33J is not always necessary and can be omitted. The material of the pipes 3 and 33 is not limited to the high tension material, and may be copper or the like. In addition, the shape of the closing portion 2 of the housing 1 is a spherical shape, and the shape of the closing portion 32 of the housing 31 is a planar shape, but may be other shapes such as a concave shape or a conical shape.

In addition, for the housings 1 and 31, the helium leak test result of the closed portions 2 and 32 is not necessarily 1 × 10 ⁻⁸ Pa · m ³ / s or less. For example, a test result of 1 × 10 ^{−5 to} 1.1 × 10 ⁻⁸ Pa · m ³ / s may be obtained.

1,31 Housing (Inflator housing for airbag)
2 Blocking portion 2a, 2c Center point 2b Surrounding line 3,33 Pipe (cylindrical member)
26, 56 Pressing part (tip part of pressing part)
r Outer diameter P Protruding part (tip part of pressing part)
Q Protruding part (tip part of pressing part)

Claims (3)

In a method for manufacturing an inflator housing for an airbag, at least one end of which is closed,
The outer peripheral diameter of the one end of the cylindrical member that is open at both ends, a plurality of punches each having a different shape of the throttle portion, and a rear side portion for making the tip of the cylindrical member a small-diameter cylindrical shape, A punch provided with a constricted portion for forming a constricted portion having a curved shape at a portion connecting a cylindrical portion having a small diameter and a portion having an original outer peripheral diameter was used in the order of gradually decreasing the diameter of the back side portion. After gradually reducing the size in multiple steps by drawing and making the inner peripheral surfaces of the cylindrical members at one end press each other, the tip of the pressing portion is made conical with the remaining portion being conical. After the process of cutting, the one end is in a closed state through the process of pressing the conical pressing part in the longitudinal direction and the internal direction of the cylindrical member using a mold. Inflator for airbag Manufacturing method of managing.   The method for manufacturing an inflator housing for an air bag according to claim 1, wherein when the outer peripheral diameter of the one end is reduced, the outer peripheral diameter of the cylindrical member is intended to be reduced, and the outer peripheral diameter thereof. A method for manufacturing an inflator housing for an air bag, comprising deforming an outer peripheral surface having a constricted portion having a curved shape having the above R value.   In the manufacturing method of the inflator housing for airbags of Claim 1 or 2, when performing the process which makes the outer periphery diameter of the said one end small and divides into multiple times, the said outer periphery diameter is made to just before by the process per time. A method for manufacturing an inflator housing for an air bag, characterized in that the range is from 70% to 95% of the value.

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