SEALED VESSEL AND METHOD OF MANUFACTURING SAME

Abstract: A sealed vessel wherein, a lid member in a ring shape is mounted to the opening of the main body of the vessel in a ring shape similar to the above and having a hollow barrel portion at the center thereof, and a method of manufacturing said sealed vessel. Inner and outer end edges of the opening portion (1a) of the main body of the vessel in the ring shape are clamped by an annular groove portion of the lid member (2) at inner and outer peripheral surfaces of the respective end edges of the opening portion so as to seal the main body (1) of the vessel, whereby mounting of the lid member to the main body of vessel can be facilitated, so that sealing work can be made smooth to permit mass production.

Description: TECHNICAL FIELD The present invention relates to a manufacturing method of a sealed container in which a container body of a ring-like shape having a hollow portion at the center includes opening portions on which a cap member of a similar ring-like shape for sealing the container body is attached. BACKGROUND ART A container of a ring-like shape is known (see figure 10) which contains explosive powder for inflating an air bag for safety of a driver and passengers of a vehicle. Such a container includes upright flange portions formed on opening portions of a container body, and these upright flange portions and edge portions of a cap member are integrally rolled and tightened, so that explosive powder or pellets (a gas generating agent) will be stored in the container body in an airtight condition. An example of this container is shown in Fig. 10. In Fig. 10, reference numeral 50 denotes a container body of a sealed container having a ring-like shape, and a hollow portion 51 is formed in the center of the container body 50. A cap member 52 having a ring-like shape of substantially the same diameter is fitted in upright flange portions 50a of the container body 50, and edge portions 52a of the cap member 52 and the upright flange portions 50a are integrally rolled and tightened inside of the container body 50. However, this container involves the following drawbacks. (1) When the outer diameter of the container body 50 is small (for example, when the container has a diameter of 60 mm or less), it is extremely troublesome to roll and tighten the container body 50 and the cap member 52 integrally in the sealing step of the container body 50. Therefore, mass-production of such containers is difficult. (2) Since it is particularly troublesome to roll and tighten the opening portions of the container having a ring-like shape and the cap member having a similar shape so as to seal up the container, mass-production of such containers is difficult. A further prior art is known from document US-A-3.953.957. This document discloses a method for sealing a cap to a container body wherein the flanges of the cap are rolled to the container. The resulting reaction forces are absorbed by a die inserted in a recess of the cap. It is an object of the present invention to provide a manufacturing method of a sealed ring-like container, in which sealing operation of a container body by attaching a cap member to it is facilitated, and especially in the case of a small-diameter container sealing operation of a container body by attaching a cap member to it is facilitated, and the method is suitable for mass-production. A corresponding manufacturing method is defined in claim 1. preferred embodiments of this method are defined in the claims 2 to 4. A container body with a ring-like opening portion is fixed on a container holding table, the opening portion of the container body is inserted between an inner edge and an outer edge of an annular flange formed on the outer periphery of a ring-like cap member, the cap member is secured on the container body by a holder die from the upper side, the container body is rotated, and a roll is contacted with said outer edge and pressed thereon to tightenedly connect the outer edge to an outer wall of the opening portion while the inner edge is tightenedly connected to an inner wall of the opening portion by the holder die, so that the cap member clamps and is secured on the container body. Consequently, the container body is fixed on the container holding table, and also, the holder die is contacted with the top surface of the cap member, so that the container is securely fixed from the upper and lower sides. At this time, since a wedge of the holder die is fitted in the annular flange formed on the outer periphery of the cap member, there is no fear that the cap member will be attached on the opening portion of the container body in a displaced condition. Further, by contacting the rotatable roll with the outer edge of the annular flange, the outer edge is strongly tightenedly connected to the outer wall of the opening portion of the container body, and also, the inner edge of the annular flange is strongly tightenedly connected to the inner wall of the opening portion of the container body by means of the outer peripheral surface of the wedge of the holder die. Thus, the annular flange of the cap member securely clamps and is fixed on the opening portion of the container body. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a manufacturing step and a manufacturing apparatus at a preparation stage for attaching a cap member on a container body in a manufacturing method according to the present invention; Fig. 2 is a cross-sectional view showing a manufacturing step and a manufacturing apparatus in a condition where the container body is sealed with the cap member in the manufacturing method according to the invention; Fig. 3 is an enlarged cross-sectional view of a portion A of Fig. 2 in the manufacturing method according to the invention; Fig. 4 is a cross-sectional view showing the container body of a ring-like shape manufactured by the manufacturing method according to the invention; Fig. 5 is a front cross-sectional view showing another embodiment of a sealed container according to the invention; Fig. 6 is a front cross-sectional view of the sealed container according to the invention shown in Fig. 5, in a condition where it is divided into a cap member and a container body; Fig. 7 is a plan view of the sealed container according to the invention shown in Fig. 5; Fig. 8 is a front cross-sectional view showing a still other embodiment of a sealed container according to the invention; Fig. 9 is a front cross-sectional view showing a modified embodiment of a sealed container according to the invention; and Fig. 10 is a front cross-sectional view showing a conventional example of a sealed container in which a cap member is attached on a container body by rolling and tightening. BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be hereinafter described with reference to the attached drawings. A method for manufacturing a container of a ring-like shape shown in Fig. 4 will be first described as one embodiment. Fig. 1 illustrates a condition in which a container holding table 3 and a raising lowering member 4 are located at the lower positions. A container body 1 and a cap member 2 are mounted on the predetermined positions of the container holding table 3. More specifically, the container body 1 is fixed on the container holding table 3, and the cap member 2 is mounted on opening portions 1a of the container body 1. Next, as shown in Fig. 2, the container holding table 3 and the raising lowering member 4 are moved upwardly until a holder die 5 is brought into contact with the top surface of the cap member 2. The holder die 5 is contacted more reliably when wedges 5a are closely fitted in the peripheries of annular flanges 2a of the cap member 2. Subsequently, a main shaft 6 connected to a power source is rotated, and the holder die 5 is rotated with the main shaft 6. Then, the container body 1 and the container holding table 3 are rotated synchronously. Since the container holding table 3 is rotatably provided on the raising lowering member 4 through bearings 10, the container holding table 3 is rotated with the container body 1 irrespective of the raising lowering member 4. Further, an outer roll 13 pivotally provided on a shaft 14 is brought into contact with an outer edge 2c from the outer peripheral side so as to tightenedly connect the outer edge 2c on an outer wall of the opening portion 1a. A U-shaped roll carrier arm 9 is attached on the raising lowering member 4 and pivotally supported thereon by a shaft 7. An inner roll 8 is pivotally provided on one end of the roll carrier arm 9, and the inner roll 8 is brought into contact with an outer edge 2c from the inner peripheral side so as to tightenedly connect the outer edge 2c on an inner wall of the opening portion 1a. The wedges 5a of the holder die 5 fitted in the annular flanges 2a of the cap member 2 serve to sustain pressing forces from the inner roll 8 and the outer roll 13. As shown in Fig. 3, the periphery of each wedge 5a presses an inner edge 2b of the annular flange 2a, and the inner edge 2b is tightenedly connected on the inner wall of the opening portion 1a. The outer roll 13 can be brought into contact with the outer edge 2c by moving the shaft 14 toward the container body 1. Also, as shown in Fig. 2, the inner roll 8 can be brought into contact with the outer edge 2c by moving a connecting link 12, which is pivotally supported on the other end of the roll carrier arm 9 through a shaft 11, toward the container body 1 (in a direction indicated by the arrow) automatically or manually, and inclining the roll carrier arm 9 about the shaft 7. In a different embodiment for manufacturing a container of an ordinary cylindrical shape, the cylindrical container can be sealed by rotating it about a center shaft, contacting an outer edge 2c with an opening portion 1a, and pressing it thereon by use of at least one of the outer roll 13 and the inner roll 8. In order to improve the sealing effectiveness, an adhesive (e.g., an epoxy-base adhesive) is applied to the inner surfaces of the annular flanges 2a and (or) the opening portions 1a of the container body 1. Thus, the sealing effectiveness of the cap member 2 with respect to the container body 1 can be further enhanced. An apparatus used in the manufacturing method according to the invention will now be described. The main shaft 6 connected to the power source is provided on an upper portion of the apparatus, and the holder die 5 is screw-fastened on the main shaft 6. The wedges 5a fitted in the annular flanges 2a of the cap member 2 are formed on the lower end of the holder die 5. The outer roll 13 pivotally attached on the shaft 14 which can be moved in parallel is provided at the side of the holder die 5 so that the outer edge 2c can be tightenedly connected on the outer wall of the opening portion 1a similarly. The container holding table 3 for fixing the cap member 2 and the container body 1 is provided under the holder die 5, and the container holding table 3 is rotatably provided on the raising lowering member 4 through the bearings 10. The container holding table 3 and the raising lowering member 4 are supported on a mount 15 and freely raised/lowered. The outer roll 13 can be contacted with or separated from the outer edge 2c by moving the shaft 14 horizontally. Also, the U-shaped roll carrier member 9 is pivotally supported on the raising lowering member 4 through the shaft 7. The inner roll 8 is pivotally attached on one end of the roll carrier member 9, and the connecting link 12 is pivotally supported on the other end of it through the shaft 11. The roll carrier member 9 is displaced about the shaft 7 by moving the connecting link 12 horizontally so that the inner roll 8 can be contacted with or separated from the outer edge 2c of the cap member 2. According to the invention, as described so far, the container body is sealed when the cap member clamps the opening portions of the container body and is secured thereon, to thereby remarkably facilitate the operation of attaching the cap member on the container body. Therefore, by the manufacturing method of the invention, mass-production of container bodies can be realized. Next, sealed containers according to the invention which are manufactured by the above-described method will be described on the basis of embodiments shown in Figs. 5 to 9. It has been understood that when an adhesive or a lining material is applied to the inner surfaces of annular groove portions 25 and (or) opening portions 23 of a container body 22, a clamping securing force of a cap member 24 with respect to the container body 22 is further strengthened, and also, the sealing effectiveness is improved. As the adhesive, a polyester-base adhesive, a nylon-base adhesive, a double-fluid adhesive, a rubber-base coating material or the like can be employed. In the sealed containers of the invention shown in Figs. 5, 6 and 8, an inner wall 26, an outer wall 27 and a bottom wall 28 of the container body 22 are all formed to have a uniform thickness. The wall thickness can be determined at a desirable value within a range of, for example, 0.1 to 0.3 mm. A sealed container shown in Fig. 8 is one embodiment in which a sealing portion 24a of a cap member 24 is formed to extend horizontally. The function of the sealed container itself does not vary in accordance with the shape of the sealing portion 24a of the cap member 24. The shape of the sealing portion 24a can be determined, as desired, corresponding to the distal configuration of a die for securely fixing the cap member 24 on a container body 22 in the manufacturing step. Fig. 9 is a front cross-sectional view of one embodiment in which, of an inner wall 26, an outer wall 27 and a bottom wall 28 of a container body 22, the inner wall 26 and the bottom wall 28 are subjected to drawing with ironing and formed to be thinner than the outer wall 27. For example, a = 0.2 mm, b = 0.15 mm, a > b can be settled. In order to inspect the sealing function of this embodiment, a container of a = 0.15 mm was sealed (by use of an acryl-base adhesive), and then, an air pressure of 0.5 MPa was applied to it as an inner pressure. However, leakage and breakage were not induced. Also, in a leakage test of a differential pressure type, a container sealed in the same manner exhibited a leakage amount of 10-4 cc/sec or less, and the container was not changed after a durability test. In the durability test (100 repetitions of exposure to 120°C to -40°C), the probability of sealing breakage was 1/5 or more. A container sealed in a method shown in Fig. 10 exhibits a leakage order of 10-3 cc/sec or more so that a large amount of adhesive must be used for decreasing the leakage amount of the initial function. In the embodiment shown in Fig. 9, the inner wall 26 and the outer wall 27 are different in thickness for the following reason. In the case where powder such as explosive or pellets (e.g., a gas generating agent composed of sodium azide and potassium nitrate) are stored in the container body 22 as a component part of an air bag system which is a safety device for an automobile, the inner wall 26 and the bottom wall 28 are broken more quickly than the outer wall 27 so that a generated high-pressure nitrogen gas can be delivered in a desired direction. Then, the high-pressure nitrogen gas efficiently inflates an air bag installed inside of a steering wheel of an automobile, which air bag can effectively protect a human body at the time of collision of the automobile. Needless to say, the container according to the invention not only serves as a component part of the air bag system for an automobile but also can contain various other materials. Further, portions subjected to drawing with ironing can be selected from the inner wall 26, the outer wall 27 and the bottom wall 28 as desired, and a rate of decrease in plate thickness owing to drawing with ironing can be set at a desirable value within a range of 8 % to 40 %. INDUSTRIAL APPLICABILITY As described heretofore, the container according to the present invention can be sealed by attaching the cap member on the opening portions of the container body easily. Especially, sealing operation of small-diameter containers of ring-like shapes can be effected quite smoothly, and mass-production of such containers can be performed. Consequently, the container of the invention can be used effectively as a component part of the air bag system which is a safety device for an automobile, a doughnut-shaped container article or a container of a similar shape of various other kinds.

Claims: A manufacturing method of a sealed container (1), comprising the steps of forming a pair of concentric annular grooves (2b,2c) in the lower surface of a ring-like cap member (2) for sealing a pair of concentric ring-like opening portions (1a) of a container body having a ring-like shape such that said opening portions (1a) will be inserted in the annular grooves (2b,2c), forming recessed concentric ring-like portions (2a,2b) of a depth corresponding to a depth of said annular grooves in the upper surface of said cap member such that a ring-like holder die (5) for the cap member will be inserted in the recessed portions (2a,2b), inserting said opening portions (1a) in said pair of annular grooves (2b,2c), inserting said holder die (5) in said recessed portions (2a,2b) of the cap member, rotating a pair of rolls (8,13) and pressing each of them on an outside section (2c) of a corresponding annular groove from inside and outside of the holder die (5), so as to tightenedly connect said opening portions of the container body to said annular grooves of the cap member, thus sealing said container body (1) with said cap member (2). A manufacturing method of a sealed container according to Claim 1, wherein adhesive is applied to the inner surfaces of said annular grooves of the cap member and/or said opening portions of the container body. A manufacturing method of a sealed container according to Claim 1, wherein said cap member and said container body are rotated by rotating said holder die, and said pair of rolls are rotated and pressed on them from inside and outside of the holder die. A manufacturing method of a sealed container according to Claim 1, wherein said container body is mounted on a rotatable container holding table (3), said cap member and said container body are rotated by rotating said holder die, and said pair of rolls is located inside and outside of the holder die so as to press on the outside sections of said annular grooves rotated.

Inventors: FUJIMORI HIKOICHIRO, FUJIMORI, HIKOICHIRO, FUJIMORI, HIKOICHIRO +DI
Applicants: NIPPON KAYAKU KK, NIPPON KAYAKU KABUSHIKI KAISHA
Application year: 1992
Main classification: B65B7
IPC codes: B65B7, B21D51