JP2000161489A - Manufacture of plastic cylindrical vessel having metal mouthpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively manufacturing a pressure vessel having a plastic inner shell of high airtight characteristics. SOLUTION: Metal mouthpieces are embedded on both ends of a plastic cylindrical vessel. In order to integral mold such an inner shell by rotational molding, a flange outer surface 10a of the metal mouthpiece and the inner surface of a molding die 14 are in contact with each other in a liquid tight manner at a center side of the flange, and then fixed. A clearance 16 in which resin is charged is formed between the flange outer surface 10a and the inner surface of the molding die 14 with the contact portion as a front. The width of the clearance 16 is 3 mm or more at the end of the flange 10d, and gradually decreased to a front 17 of the clearance 16, showing the minimum value at the front 17. An airtight pressure vessel can inexpensively be manufactured by charging resin in the clearance 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure vessel in which a base and a plastic cylindrical vessel are integrally formed by a rotational molding method. The pressure vessel manufactured by this manufacturing method can be applied to air respirators, various types of gas vehicles, household gas, and the like.

[0002]

2. Description of the Related Art A pressure vessel combining a metal base and a plastic cylindrical vessel is disclosed in Japanese Patent Application Laid-Open No. 1-299400. Here, a method has been adopted in which a metal base having a surface coated with a thermoplastic resin layer in advance is fixed to the outside of both poles of a plastic cylindrical container and is rotationally molded.

On the other hand, a pressure vessel formed by a rotational molding method and a manufacturing method thereof are also known in Japanese Patent Application Laid-Open No. Hei 7-158798. There, as a method of embedding and fixing the base in a plastic cylindrical container, a sufficient gap is formed between the inner surface of the mold and the base flange to allow the molten resin to enter, and the resin that has flowed into this gap is formed after molding. It is said that some of them will be removed by cutting.

[0004]

In the inner shell of a pressure vessel in which a metal die and a plastic cylindrical container are combined, a metal die is fixed to both outer sides of a plastic cylindrical container, and a conventional method of rotational molding is used. Since it is difficult to provide airtightness and sufficient bonding strength at the bonding surface between the base and the plastic cylindrical container, it is necessary to devise a method such as providing an adhesive layer on the surface of the metal base before forming. However, when mass production is considered, there are problems that it is difficult to form a uniform adhesive layer and that the number of steps for forming the adhesive layer increases.

On the other hand, a method of embedding the entire flange portion of a metal die in a plastic cylindrical container by rotational molding is as follows.
This is effective as a method for maintaining airtightness and sufficient strength at the joint between the plastic cylindrical container and the metal base. However, in the conventional method in which a resin-unfilled portion is likely to be generated in a gap between the mold inner surface and the flange outer surface, the mold inner surface shape is formed such that a thickened resin layer including the unfilled portion is formed on the flange outer surface. Therefore, a step of cutting and removing a part of the resin layer including the unfilled portion after the molding is required. For this reason, it is easily presumed that material loss occurs due to cutting, and that manufacturing costs increase due to an increase in steps.

[0006] The present invention solves the above problems, and is inexpensive.
The present invention has been made in order to provide a method of manufacturing a pressure vessel having an inner shell formed by integrally molding a plastic cylinder having high gas tightness and a metal base.

[0007]

SUMMARY OF THE INVENTION According to the present invention, the above object is achieved by integrally molding an inner shell in which metal caps are embedded in both poles of a plastic cylindrical container by rotational molding. By devising the shape of the flange outer surface of the metal base, the outside of the flange portion is brought into liquid-tight contact with the inner surface of the molding die on the center side of the flange, and the contact portion is used as the tip to contact the outer surface of the flange with the inner surface of the die. A gap to be filled with resin is provided, the width of the gap (the length of a normal drawn from the flange to the inner surface of the mold) is 3 mm or more at the end of the flange, and the width of the gap is set at the tip of the gap. With the manufacturing method that gradually decreases toward the end and minimizes at the tip,
Preferably, the problem is solved by a manufacturing method characterized in that the flange end face of the metal base has at its end an end face whose inclination angle 19 with respect to the cylindrical axis of the plastic cylindrical container is 0 ° to + 45 °. You.

More specifically, the metal base can have a tubular neck having a threaded structure inside and an annular flange extending radially from one end of the tubular neck for inserting a valve. The part further includes a flange outer surface having an inclination angle of 0 ° to + 45 ° with respect to the cylindrical axis of the plastic cylindrical container at a boundary portion between the flange outer surface facing the mold inner surface and the flange inner surface facing the inside of the container. It can have a part (end face). When the outer surface of the flange has the above-mentioned end surface, if the width of the outer surface of the flange and the inner surface of the mold is 3 mm or more at the beginning of the end surface, the molten resin is solidified first in the vicinity of the end of the flange to prevent the resin from flowing toward the tip of the gap. The possibility of inhibition can be made extremely low. Also, chamfering or rounding of the flange end is effective for suppressing stress concentration from occurring in the plastic cylindrical container due to internal pressure and for sufficiently widening the gap entrance.

The angle of the flange end face facilitates the flow of powdery resin into the gap during molding, and at the time of solidification of the molten resin, maintains the contact pressure at the interface between the flange end face and the resin caused by heat shrinkage. Works effectively to give sufficient strength to

The fiber reinforced layer plays a role of maintaining a strength capable of withstanding the internal pressure of the pressure vessel, and long fibers are formed around the outer periphery of the plastic cylindrical container together with the thermosetting resin by a filament winding method or the like. It is wound and laminated in parallel and oblique directions to the circumferential direction. The plastic cylindrical container serves to prevent the permeation of the gas filled therein, and comprises a cylindrical portion having no change in the cross-sectional area of the container and dome-shaped dome portions formed at both ends of the cylindrical portion. A base is embedded and fixed at both poles located at the top of the portion and on the central axis of the cylindrical portion.

[0011]

According to the rotary molding method, the filling pressure is not applied, and the powdery resin moves inside the mold under the influence of gravity and gradually melts from the powdery resin in contact with the inner surface of the mold. To go. For this reason, at the corners such as the boundary between the tubular neck and the outer surface of the flange, the resin generally flows depending on the position of the mold in a manner that opposes the gravity, so that the resin is not sufficiently filled and becomes an unfilled portion.

In the present invention, the gap formed between the outer surface of the flange of the metal die and the inner surface of the die, which is installed and fixed in the opening located at the center of both end walls of the die, becomes narrower toward the inner part. It has a structure. In such a structure, the powdery resin is densely filled from the tip of the gap with the same effect as the funnel, and the filled powdery resin melts in order from the one introduced into the tip of the gap due to the difference in heat capacity. Begin to. Also,
The angle of the flange end face should make the entrance of the gap wide enough,
The possibility that the resin is melted and fixed near the entrance first, and the possibility of obstructing the flow of the resin toward the tip of the gap is extremely reduced. Further, in the integrally formed inner shell, a contact pressure is generated in a direction perpendicular to the axis of the plastic cylindrical container at a boundary between the metal cylindrical base and the flange outer surface due to the thermal shrinkage of the plastic cylindrical container after the molding. When the angle of the flange end face is 0 °,
All contact pressure is received at the flange end face. At + 45 °, the sliding force on the flange end face and the force acting on the flange end face in the vertical direction are balanced. As a result of intensive studies, in order to obtain sufficient bonding strength that can withstand the tension of the fiber loaded during the formation of the reinforcing fiber layer by filament winding, at least half of the force caused by heat shrinkage should be perpendicular to the flange end face. It was confirmed that receiving pressure was appropriate.

[0013]

According to the present invention, when the flange portion of the metal base is embedded and fixed inside the plastic cylindrical container,
By providing a gap between the outer surface of the flange and the inner surface of the mold that minimizes the possibility of unfilled portions, the seam has sufficient strength to withstand the tension of the reinforcing fibers applied during the formation of the fiber reinforced layer. The inner shell of the pressure vessel having no cracks can be formed without performing secondary processing such as cutting. In addition, since the fiber reinforced layer, which is the outer shell, serves as a strength member, deformation of the embedded metal base is minimized, and a self-sealing effect is provided at the interface between the base and the cylindrical container by an internal pressure. The container can be manufactured at low cost.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the pressure vessel according to the present invention.
The pressure vessel has an inner shell 12 integrally formed by a rotational molding method.
And an outer shell 13 formed by filament winding. The inner shell 12 includes the base 6 and a plastic cylindrical container 12d. 12d plastic cylindrical container
Consists of a cylindrical portion 12b and a hemispherical dome portion 12a in contact with both ends thereof.

The dome portion 12a is embedded so that the center axis of the cylindrical portion and the center axis of the tubular neck 9 of the base 6 coincide with both poles thereof, and the tubular neck 9 projects outside.

The outer shell 13 is formed by laminating long fibers impregnated with an unsaturated polyester resin, phenol resin, epoxy resin, or the like, in a hoop winding or helical winding by filament winding, and then performing a curing treatment. As long fibers, glass fibers, carbon fibers, aramid fibers, or any combination thereof can be used.

As the resin material of the plastic cylindrical container, polyethylene resin, polyamide resin, polystyrene resin, polyolefin resin, polycarbonate resin and the like are used.

Particles having a diameter substantially in the range of 100 to 300 μm are used.

FIG. 2 shows a base which is embedded and fixed in a plastic cylindrical container.

The base 6 is made of a material such as stainless steel, aluminum alloy, or titanium alloy by cutting, casting, or forging, and has an annular flange portion 10 extending at one end of a tubular neck 9 in a radial direction. , A female screw 8 for mounting a valve or the like inside the tubular neck 9
And a seal ring groove 11 for mounting the seal ring.

The flange portion includes a flange outer surface 10a fixed to be in contact with the mold inner surface 14g, a flange inner surface 10b facing the inside of the container, a flange end surface 10c sandwiched between the flange inner and outer surfaces, and a flange end surface 10c and the flange outer surface 10a. And a flange end 10d appropriately rounded to introduce resin.

FIG. 3 shows a positional relationship between a die for rotational molding for forming an inner shell and a die.

The mold 14 has cylindrical portions 14a and 14b, hemispherical end walls 14c starting from the ends of the cylindrical portions, an annular flange 14e located at the center of the cylindrical portion, and a tubular neck of a base. Set hole 14f
Consists of

Hereinafter, the description will be made along the flow of manufacturing the pressure vessel. First, the mold is opened from the flange portion 14e. Next, the base 6 is fixed to the center of both end walls 14c so that the center axis of the die body and the center axis of the tubular neck 9 of the base 6 coincide. Specifically, a through hole 15 for degassing is provided inside.
A bolt 15 having a is inserted into a through hole 14d having the same central axis as the mold 14, a male screw 15b is screwed into the female screw 8 of the base 6, and the flange outer surface 10a is fixed so as to be in contact with the mold inner surface 14g. At this time, a gap 16 is formed between the mold inner surface 14g and the flange end surface 10c. Next, an appropriate amount of powdered resin is charged, and the mold 14 is placed on the annular flange surface 14.
Close with e. More specifically, in order to position the mold so that a step does not occur on the inner surface 14g of the mold, a plurality of through holes provided on the outer periphery of the flange are fastened with bolts, nuts, or the like. Thereafter, the mold is attached to a rotary molding machine, and molding conditions such as a molding temperature, a molding time, and a cooling time suitable for a resin to be used are determined. Generally, molding is performed by rotating the mold biaxially at a low speed of 10 revolutions per minute or less while applying heat from the outer surface of the mold so that the inside of the mold is at or above the melting point of the resin. This is done by adhering to the inner surface of the mold.

After molding, a cooling step and a releasing step are performed to obtain an inner shell in which the base and the container body are integrally formed. Then, as a final step, a fiber reinforced layer is formed by filament winding so that all parts except the tubular neck part of the inner shell are included.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pressure vessel.

FIG. 2 is a sectional view of a base.

FIG. 3 is a sectional view showing a positional relationship between a rotational molding die and a die.

FIG. 4 is a cross-sectional view (details) showing a positional relationship between a rotational molding die and a die.

FIG. 5 is a cross-sectional view (details) showing a positional relationship between a rotational molding die and a die.

[Explanation of symbols]

 6 Cap 7 Bolt 8 Female thread 9 Tubular neck 10 Flange part 10a Flange outer surface 10b Flange inner surface 10c Flange end face 10d Flange end part 11 Seal ring groove 12 Inner shell 12a Dome part 12b Cylindrical part 12d Plastic cylindrical container 13 Outer shell 14a Mold 14b Mold 14c End wall 14d Through hole 14e Annular flange 14f Cap setting hole 14g Mold inner surface 15 Bolt 15a Through hole 15b Male screw 16 Gap 17 Gap tip 18 Gap entrance 19 Inclination angle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromitsu Takamoto 2-1 Hinode-machi, Iwakuni-shi, Yamaguchi Prefecture Inside the Iwakuni Research Center, Teijin Limited (72) Inventor Katsuji Mimatsu 322-2, Futatsuka, Takaoka-shi, Toyama Pref. Takagi Seiko F-term (reference) 3E072 AA10 CA01 3J046 BA03 BB02 BC13 CA01 CA04 DA10 EA01

Claims (4)

[Claims] 1. A plastic with a metal base, which can be used for manufacturing a pressure vessel having a fiber reinforced layer as an outer shell and a molded article in which a metal base is inserted into a part of a plastic cylindrical container as an inner shell. A method for manufacturing a cylindrical container, comprising: integrally molding a plastic cylindrical container with a metal base in which the metal base is embedded in both poles of a plastic cylindrical container by rotational molding; a flange outer surface of the metal base; And the inner surface of the molding die is fixed so as to make a liquid-tight contact on the center side of the flange, and a gap is provided between the outer surface of the flange and the inner surface of the mold with the contact portion as the tip, The width of the gap (the length of the normal drawn from the flange to the inner surface of the mold) is 3 mm or more at the end of the flange.
The method of manufacturing a plastic cylindrical container with a metal mouthpiece, wherein the width of the gap gradually decreases toward the tip of the gap, and the gap is minimized at the tip. 2. A flange end face located at the outermost periphery of a flange portion of a metal base has an end portion having an inclination angle (19) of 0 with respect to a cylindrical axis of a plastic cylindrical container.
The method for producing a plastic cylindrical container with a metal mouthpiece according to claim 1, wherein the method has an end surface at an angle of 45 to 45 °. 3. The plastics powder used for rotational molding has a particle size of substantially 100 to 300 μm.
2. A method for producing a plastic cylindrical container with a metal base according to any one of (1) to (2). 4. The method according to claim 3, wherein said plastics is selected from polyethylene, polyamide and polycarbonate.