JP6741444B2 - Easy-open container lid - Google Patents

Description

The present invention relates to a container having a cylindrical mouth-neck portion in which an annular locking projection is formed on the upper end of the outer peripheral surface, particularly, but not limited to, a container for storing a carbonated beverage. An easily-openable container lid, more specifically, a circular top surface wall, a skirt wall extending radially outward and downward in a longitudinal sectional view from the peripheral edge of the top surface wall in an arc shape, and then vertically extending downward, and from the lower end of the skirt wall. The present invention relates to an easy-open container lid including a shell including an extending gripping piece and a disc-shaped synthetic resin liner disposed on an inner surface of a top wall of the shell.

The following Patent Documents 1 and 2 disclose an easy-open container lid for a container having a cylindrical mouth-neck portion in which an annular locking projection is formed on the upper end of the outer peripheral surface. Such a container lid includes a circular top wall, a skirt wall extending radially outward and downward in a vertical cross-sectional view from a peripheral edge of the top wall, a skirt wall extending vertically downward, and a gripping piece extending from a lower end of the skirt wall. And a disc-shaped synthetic resin liner disposed on the inner surface of the top wall of the shell. At least a part of the gripping piece together with the top wall and the skirt wall of the shell are integrally formed from a metal thin plate such as an aluminum-based alloy thin plate. The shell is further formed with a pair of scores having a first portion extending upwardly from the both sides of the gripping piece and the skirt wall and a second portion extending from the first portion to a circular arc along the peripheral edge of the ceiling wall. Has been done. The liner is formed by supplying a soft or molten synthetic resin material to the inner surface of the top wall of the shell and embossing the synthetic resin material.

In the container lid disclosed in Patent Document 1, the liner extends radially outward beyond the arc-shaped second portions of the pair of scores. In the container lid having such a configuration, when the liner is bonded to the shell in the portion existing over the arc-shaped second portions of the pair of scores, the arc-shaped second portions of the pair of scores are attached. Is virtually impossible to break. Therefore, the liner is locally placed in a non-bonded or weakly bonded state with respect to the shell in a portion existing over the second portion of the pair of scores extending in an arc shape. More specifically, one side of the thin metal plate, that is, the side defining the inner surface of the top wall, is coated over its entire surface with adhesive properties for the liner, but for the shell. In the part where the liner needs to be in a non-adhesive or weakly adhered state, the surface of the coating having an adhesive property with respect to the liner is further locally coated with the non-adhesive or weak adhesive property with respect to the liner. ..

On the other hand, in the container lid disclosed in Patent Document 2, the liner does not extend beyond the second portion extending in the arc shape of the pair of scores, and the liner as a whole has the arc shape of the pair of scores. Is located radially inward of the second portion extending to.

Japanese Patent No. 4065690 JP, 2015-40060, A

Thus, in the container lid disclosed in Patent Document 1, in addition to applying a coating having adhesive properties to the liner on one surface of a thin metal plate for forming a shell, the container lid is adhered to the liner. Even if the contents are carbonated drinks and the internal pressure of the container is high, a specific area on the surface of the coating having the characteristics is further locally coated with a non-adhesive or weakly adhesive property to the liner. It is possible to arrange the score relatively inward when viewed in the radial direction to improve the sealing and opening properties of the mouth and neck, but it is necessary to apply a coating having non-adhesive or weak adhesive properties. Therefore, there is a problem to be solved that the manufacturing process of the container lid becomes complicated and the manufacturing cost increases due to this.

Since the container lid disclosed in Patent Document 2 is a type that does not have the coating having the non-adhesive or weakly adhesive property described above, the above-mentioned problems existing in the container lid disclosed in Patent Document 1 are However, according to the experience of the present inventors, there are the following problems to be solved. That is, when the liner is arranged only within the arc-shaped second portion of the pair of scores without extending radially outward beyond the arc-shaped second portion of the pair of scores. The outer diameter of the liner is limited to a relatively small value, and thus the outer diameter of the cylindrical sealing hanging piece formed on the outer peripheral portion of the liner is generally limited to a relatively small value. And, due to the outer diameter of the drooping piece for sealing being limited to a relatively small value, the drooping piece for sealing should be located radially inward of the annular uppermost part on the top surface of the mouth and neck of the container. Therefore, when the container lid is attached to the mouth and neck, the hanging member for sealing tends to be caught inside the mouth and neck without being positioned as required with respect to the mouth and neck. In order to solve such a problem, the disposition position of the arc-shaped second portions of the pair of scores is displaced radially outward to be the outermost peripheral edge of the top wall or the upper end of the skirt wall, and the liner It is also contemplated to increase the maximum outer diameter allowed. However, when such a solution is adopted, when the content of the container is a carbonated drink and the internal pressure of the container is relatively large, the container lid is detached from the mouth and neck of the container to open the mouth and neck. At this time, prior to the pressure inside the container being released, the restraint of the shell on the mouth and neck is excessively released during the rupture of the arc-shaped second portion of the pair of scores. There is a risk that the lid may accidentally fly from the mouth and neck (generally called a blow-off phenomenon). In a container lid of a type that does not have a coating having non-adhesive or weakly adhesive properties, the score can be arranged only outside the outer diameter of the liner, as described above. As described above, the score position cannot be set inward of the top wall (inward of the outer diameter of the liner).

The present invention has been made in view of the above facts, and its main technical problem is to apply a coating having adhesive properties to a liner on one surface of a thin metal plate for forming a shell, Even though it is not necessary to locally apply a coating having non-adhesive or weakly adhesive property to the liner at a specific portion of the surface of the coating having adhesive properties, the container lid is attached to the mouth and neck of the container. Part of the liner is prevented from being caught inside the mouth and neck during fitting, the liner is positioned as desired with respect to the mouth and neck, and the container lid is again removed from the mouth and neck. (EN) Provided is a new and improved easy-open container lid in which the container lid does not accidentally fly radically when opening the mouth and neck, and such a new and improved easy-open container lid. It is an object of the present invention to provide a new and improved method of manufacturing an openable container lid.

According to the first aspect of the present invention, as an easy-open container lid that achieves the above-mentioned main technical problems, a container having a cylindrical mouth-neck portion in which an annular locking projection is formed on the upper end of the outer peripheral surface. Is an easy-open container lid for
A circular top wall, a skirt wall extending radially outward and downward in a vertical cross-sectional view from a peripheral edge of the top wall in a circular arc shape, and then vertically extending downward, and a grip piece extending from a lower end of the skirt wall, At least a part of the gripping piece together with the top wall and the skirt wall is integrally formed from a thin metal plate, and a first portion and a first portion extending upward from the skirt wall from both sides of the gripping piece. Next, from a shell in which a pair of scores having a second portion extending in an arc shape along the peripheral edge of the top wall is formed, and a disc-shaped synthetic resin liner disposed on the inner surface of the top wall. In the configured easy-open container lid,
The liner is adhered to the inner surface of the top wall radially inward of the pair of scores, and the outer peripheral edge portion of the liner extends downward in the radial direction and extends downward to incline the top wall. Is separated from the inner surface ,
In a state before being fitted to the mouth-neck portion of the container, the outer peripheral edge of the liner is located radially outside of the second portion of the pair of scores,
An easily-openable container lid is provided.

Good Mashiku is on the top surface of the mouth-neck has an annular top portion is defined in the radial direction central portion, than the annular top portion of said top surface of the outer peripheral edge the mouth and neck of the liner It is located 1.0 to 2.0 mm outward in the radial direction .

According to the second aspect of the present invention, as a method for manufacturing an easy-open container lid that achieves the above-mentioned main technical problems, a shell forming step of machining the thin metal plate to form the shell,
A synthetic resin material supplying step of supplying a synthetic resin material in a heat-melted or softened state to the inner surface of the top wall of the shell;
The synthetic resin material is embossed, and the outer peripheral edge is located radially inward of the pair of scores and adhered to the inner surface of the top wall, and the outer peripheral edge is separated from the inner surface of the top wall. A liner preformed body forming step of forming a liner preformed body in which a cylindrical hanging part extending vertically in a direction to be formed is formed,
A liner shaping step of deforming the hanging portion of the liner preform into a shape that is inclined in a direction separating from the inner surface of the ceiling wall toward the outside in the radial direction;
There is provided a method comprising:

Preferably, a coating having adhesive properties to the synthetic resin material is applied to one surface of the metal thin plate, and in the shell forming step, the one surface defines the inner surface of the top wall. Add machining to a thin plate. In the liner shaping step, it is preferable to apply a heated shaping tool to the hanging part of the preformer of the liner to deform the hanging part. In the liner shaping step, a heated primary shaping tool is caused to act on the hanging portion of the liner pre-molded body so that the inner peripheral surface of the hanging portion extends radially outward at an inclination angle α of the top wall. The inner peripheral surface of the hanging part is larger than the tilt angle α by deforming into a shape inclined in a direction away from the inner surface and then applying a heated secondary shaping tool to the hanging part of the liner preform. It may be deformed in such a manner as to be inclined outward in the radial direction at an inclination angle β in a direction away from the inner surface of the ceiling wall. Preferably, the gripping piece of the shell includes a base portion integrally formed from the thin metal plate with the ceiling wall and the skirt wall, and a ring-shaped portion formed of a synthetic resin. A thin metal plate is machined to form the base of the gripping piece with the top wall and the skirt wall of the shell, and then the ring-shaped portion of the gripping piece is molded from the synthetic resin and the gripping piece of the gripping piece is formed. Connect to the base.

In the easy-open container lid of the present invention, the liner is positioned radially inward of the pair of scores, and therefore, one side of the metal thin plate for forming the shell is coated with a coating having adhesive properties to the liner. In addition, it is not necessary to locally apply a coating having non-adhesive or weakly adhesive property to the liner to a specific portion of the surface of the coating having adhesive property to the liner, but the outer peripheral edge of the liner has a radius. In the state before it is fitted to the mouth and neck of the container, the outer peripheral edge of the liner is the first of a pair of scores in the state in which it extends downward in the direction outward and is separated from the inner surface of the top wall . Since it is located radially outward of the second part, the second part of the pair of scores is not excessively radially outwardly positioned, and therefore the container lid is detached from the mouth and neck to open the mouth and neck. It is possible to set the outer diameter of the liner to a sufficiently large value without accidentally flying the container lid accidentally when doing so, and therefore when installing the container lid on the mouth and neck of the container, Part of it is prevented from being caught inside the mouth and neck and the liner can be positioned as desired with respect to the mouth and neck. Further, according to the method for producing the easy-open container lid of the present invention, the easy-open container lid of the present invention can be efficiently and appropriately manufactured.

FIG. 3 is a perspective view of a preferred embodiment of a container lid constructed in accordance with the present invention. AA sectional drawing of the container lid shown in FIG. FIG. 2B is a cross-sectional view taken along the line BB illustrating the step of molding the liner of the container lid shown in FIG. 1. The figure which shows the state which fitted the container lid shown in FIG. The figure which shows the state which attached the container cover shown in FIG. 1 to the mouth-neck part.

Hereinafter, a more detailed description will be given with reference to the accompanying drawings showing a preferred embodiment of an easily openable container lid configured according to the present invention.

Referring to FIGS. 1 and 2, the container lid, generally designated by the numeral 2, is composed of a shell 4 and a liner 6.

The shell 4 has a circular top wall 8, a skirt wall 10 hanging from the peripheral edge of the top wall 8, and a gripping piece 12 extending from the lower end of the skirt wall 10. The top wall 8 is expediently flat over its entire surface. The skirt wall 10 extends radially outward and downward in a circular arc shape in FIG. 2 (longitudinal sectional view) from the peripheral edge of the top wall 8 and then extends vertically downward. Two notches 14a and 14b are formed in the lower end of the skirt wall 10 at predetermined intervals in the circumferential direction. The gripping piece 12 extends somewhat vertically downwards from the lower end of the skirt wall 10 in a circumferential region between the notches 14a and 14b formed in the skirt wall 10 and then extends radially outward. And a ring-shaped portion 18 connected thereto. As will be clearly understood by referring to FIG. 2, in the illustrated embodiment, the base 16 of the gripping piece 12 together with the top wall 8 and the skirt wall 10 are integrally formed from a thin metal plate such as an aluminum base alloy. The ring-shaped portion 18 of the gripping piece 12 is formed of a synthetic resin such as polyethylene or polypropylene (which will be further referred to later). If desired, the ring-shaped part 18 of the gripping piece 12 can also be integrally formed from a thin metal plate.

The shell 4 is further formed with a pair of scores 20a and 20b. Each of the pair of scores 20a and 20b includes a first portion 20a-1 and 20b-1 extending upward from the both sides of the gripping piece 12 in the skirt wall 10, more specifically, the cutouts 14a and 14b, and a ceiling. The peripheral portion of the face wall 8 has second portions 20a-2 and 20b-2 extending in an arc shape. In the illustrated embodiment, the pair of scores 20a and 20b also include extended ends 20a-3 and 20b-3 extending further down the skirt wall 10 from the second portions 20a-2 and 20b-2. There is.

Continuing the description with reference to FIG. 2, a liner 6 formed of a suitable synthetic resin such as low density polyethylene is provided on the inner surface of the top wall 8 of the shell 4. The liner 6 is disc-shaped as a whole and has a thin central portion 22 and a thick peripheral portion 24. The liner 6 is adhered to the inner surface of the top wall 8 radially inward of the pair of scores 20a and 20b of the shell 4 (see FIG. 3(d)), and the outer peripheral edge portion 26 of the liner 6 is radial. It is important that it is inclined downwardly toward the outside and is separated from the inner surface of the top wall 8. In the illustrated embodiment, the outer peripheral edge portion of the thick peripheral edge portion 24, that is, the outer peripheral edge portion 26 of the liner 6 is inclined radially outward in a direction away from the inner peripheral surface of the top wall 8. Its inner peripheral surface has an inclination angle β. The outer peripheral edge of the liner 6 is located radially outside the second portions 20a-2 and 20b-2 of the pair of scores 20a and 20b. On the other hand, a seal piece 28 that hangs downward is formed on the inner peripheral edge of the thick peripheral edge 24.

Then, the manufacturing method of the container lid 2 mentioned above is demonstrated. First, the shell 4 is formed by the shell forming step. In the shell forming step, a coating having adhesive properties is applied to the liner 6 on one surface of a thin metal plate such as an aluminum-based alloy, that is, the surface corresponding to the inner surface of the shell 4. Such a coating may be, for example, a polyethylene coating when the liner 6 is formed from soft polyethylene. On the other hand, the other surface of the thin metal plate, that is, the surface corresponding to the outer surface of the shell 4, is coated with an appropriate protective paint and is subjected to required printing. Furthermore, a groove forming a pair of scores 20a and 20b is formed on one surface or the other surface of the metal thin plate by applying an appropriate tool. In the illustrated embodiment, such grooves are formed in the other surface of the sheet metal, that is, the surface corresponding to the outer surface of the shell 4. Then, appropriate machining such as punching and drawing is applied to the thin metal plate to form the top wall 8, the skirt wall 10 and the base 16 of the gripping piece 12. At this time, the metal thin plate is machined so that one surface of the metal thin plate defines the inner surface of the top wall 8. Next, a process of forming the ring-shaped portion 18 of the grip piece 12 will be described. In this molding step, a ring-shaped portion 18 is formed by injection molding or compression molding a suitable synthetic resin material such as polypropylene or polyethylene. At this time, the ring-shaped portion 18 is connected to the base portion 16 at the same time as the molding, using the base portion 16 formed of a thin metal plate as a so-called core. Thus, the shell 4 is formed. The shell forming process itself is well known to those skilled in the art, and thus detailed description thereof will be omitted.

Next, the molding process of the liner 6 will be described with reference to FIG. When molding the liner 6, first, as shown in FIG. 3A, a synthetic resin material 30 such as low-density polyethylene in a heat-melted or softened state is supplied to the inner surface of the top wall 8 of the shell 4 (synthetic resin material supply). Process). Then, the synthetic resin material 30 is subjected to embossing by applying an embossing tool 32 shown by a chain double-dashed line in FIG. 3B to form a liner preform 34 as shown in FIG. 3B (liner). Pre-molded body molding process). The outer peripheral edge of the liner preform 34 is located slightly inward of the pair of scores 20a and 20b of the shell 4 in the radial direction. The pre-liner molded body 34 has a disc shape as a whole, and has a thin central portion 22 and a thick peripheral portion 24. The thick peripheral portion 24 has an outer peripheral portion formed with a hanging portion 26 ′ that extends downward substantially perpendicularly to the top wall 8 of the shell 4, and the thick peripheral portion 24 has an inner peripheral portion that extends downward. A hanging seal piece 28 is formed. As described above, since the inner surface of the shell 4 is coated with the adhesive property with respect to the synthetic resin material 30 (liner 6), the liner pre-molded body 34 covers the entire inner surface of the top surface wall 8. To be glued. Then, the hanging part 26' of the pre-liner molded body 34 is deformed into a shape that is inclined downward in the radial direction (liner shaping step). In the liner shaping step, the heated molding tool is acted on the hanging part 26 ′ of the pre-liner molded body 34 to deform the hanging part 26 ′. At this time, first, the heated primary forming tool 36 shown by the chain double-dashed line in FIG. 3(c) is caused to act on the hanging portion 26′ of the pre-liner forming body 34, and as shown in FIG. 3(c). In the form in which the inner peripheral surface of the hanging portion 26 ′ is inclined in the direction away from the inner surface of the top wall 8 toward the outer side in the radial direction at an inclination angle α (preferably 20°≦α≦40°). It deforms (the hanging part in such a form is designated as 26″), and then the heated secondary forming tool 38 indicated by a chain double-dashed line in FIG. 3D is applied to the hanging part 26″ of the liner preform 34. As shown in FIG. 3( d ), the inner peripheral surface is moved upward in the radial direction at an inclination angle β (preferably 40°≦β≦60°) larger than the inclination angle α. Conveniently, it is transformed into a final form (outer peripheral edge portion 26) that is inclined in a direction away from the inner surface of the face wall 8. Deformation of the hanging part 26' can be performed by directly acting the secondary forming tool 38 by omitting the action of the primary forming tool 36, but the hanging part 26' can be formed into a desired shape without damage. In order to stably deform, it is preferable that the forming tool is made to act in two steps or three steps or more and then gradually performed.

FIG. 4 also shows the container lid 2 and the mouth/neck portion 40 of the container which is sealed by the container lid 2. The mouth-neck portion 40 of the container, which can be formed of a suitable synthetic resin such as glass or polyethylene terephthalate, has a substantially cylindrical shape as a whole, and an annular locking ridge 42 is formed on the upper end portion of the outer peripheral surface thereof. An annular uppermost portion 44 is defined on the top surface of the mouth/neck portion 40 at the center in the radial direction.

For example, when the container lid 2 is attached to the mouth/neck portion 40 of a container filled with a gas-containing liquid such as cider or cola which is a carbonated beverage to seal the mouth/neck portion 40, first, as shown in FIG. The container lid 2 is fitted on the neck 40. As understood by referring to FIG. 4, when the container lid 2 is fitted on the mouth/neck portion 40, the outer peripheral edge of the liner 6 is more than the annular uppermost portion 44 on the top surface of the mouth/neck portion 40. It is located radially outward by a distance X. The distance X is preferably 1.0 to 2.0 mm. Next, the container cover 2 is pressed downward with the container cover 2 fitted on the mouth/neck portion 40. In the easy-open container lid of the present invention, the outer peripheral edge portion of the liner 6 extends obliquely downward in the radial direction and is spaced apart from the inner surface of the top wall 8 to cover the mouth/neck portion 40. In the state before being fitted, the outer peripheral edge of the liner 6 is located radially outside the second portions 20a-2 and 20b-2 of the pair of scores 20a and 20b. Therefore, in addition to applying a coating having adhesive properties to the liner 6 to one side of the thin metal plate for forming the shell 8, it is further provided on a specific portion of the surface of the coating having adhesive properties to the liner 6. It is not necessary to locally apply a coating having non-adhesive or weakly adhesive properties to the liner 6, but the second portions 20a-2 and 20b-2 of the pair of scores 20a and 20b are excessively radially outwardly moved. The outer diameter of the liner 6 can be set to a sufficiently large value without positioning, and therefore, when the container lid 2 is attached to the mouth/neck portion 40 of the container, a part of the liner 6 is not covered by the mouth/neck portion 40. The liner 6 can be positioned with respect to the mouth/neck portion 40 as required by preventing the liner 6 from being caught inside. After pressing the container lid 2 downward against the mouth/neck 40, the skirt wall 10 of the shell 4 of the container lid 2 is deformed inward in the radial direction while maintaining such a pressed state, and thus the annular shape of the mouth/neck 40 is formed. The lower portion of the skirt wall 10 is locked to the locking projection 42 (see FIG. 5). As can be clearly understood by comparing FIG. 4 and FIG. 5, the thick-walled peripheral portion 24 of the liner 6 is pressed against the top surface of the mouth/neck portion 40. An outer peripheral edge portion 26 formed by deforming the hanging portion 26 ′ is extended radially outward along the top surface of the mouth/neck portion 40 and is formed on the upper end of the skirt wall 10 of the shell 2. The pair of scores 20a and 20b extend radially outward beyond the second portions 20a-2 and 20b-2. The seal piece 28 extends radially inward along the top surface of the mouth/neck portion 40.

When the container lid 2 is detached from the mouth/neck 40 and the mouth/neck 40 is opened to consume the contents of the container, a finger is applied to the ring-shaped portion 18 of the gripping piece 12 of the shell 4 to grasp the container. The piece 12 is forced radially outward and then upwardly or diametrically opposite to break the pair of scores 20a and 20b formed in the shell 4. At this time, along with the deformation of the shell 4, the liner 6 is also displaced upward and gradually released from the mouth/neck portion 40 of the container, and the inside of the container is opened to the atmosphere (internal pressure is released). In the easily openable container lid 2 of the present invention, it is not necessary to excessively position the second portions 20a-2 and 20b-2 of the pair of scores 20a and 20b outwardly in the radial direction, as described above. Even when the content is a gas-containing liquid and the internal pressure of the container is relatively high, the second portion 20a− extending in an arc shape of the pair of scores 20a and 20b before the pressure in the container is released. The restraint of the shell 6 on the mouth/neck portion 40 is excessively released when the fracture of 2 and 20b-2 is being performed, so that the container lid 2 does not accidentally and extremely fly from the mouth/neck portion 40. Then, when the pair of scores 20a and 20b is broken to a predetermined extent, the lower end of the skirt wall 10 of the shell 8 with respect to the annular locking projection 42 formed on the neck portion 40 of the container is gradually released. Therefore, the entire container lid 2 is separated from the mouth/neck portion 40, and the mouth/neck portion 40 is opened.

2: Container lid
4: Shell
6: Liner
8: Top wall 10: Skirt wall 12: Grip piece 20a: Score 20b: Score 20a-1: First part of score 20b-1: First part of score 20a-2: Second part of score 20b- 2: Second part of score 26: Outer peripheral edge of liner 26': Hanging part 40: Mouth and neck of container 42: Annular locking ridge

Claims (7)

An easy-open container lid for a container having a cylindrical mouth-neck portion in which an annular locking projection is formed on the upper end of the outer peripheral surface,
A circular top wall, a skirt wall extending radially outward and downward in a vertical cross-sectional view from a peripheral edge of the top wall in a circular arc shape, and then vertically extending downward, and a grip piece extending from a lower end of the skirt wall, At least a part of the gripping piece together with the top wall and the skirt wall is integrally formed from a thin metal plate, and a first portion and a first portion extending upward from the skirt wall from both sides of the gripping piece. Next, from a shell in which a pair of scores having a second portion extending in an arc shape along the peripheral edge of the top wall is formed, and a disc-shaped synthetic resin liner disposed on the inner surface of the top wall. In the configured easy-open container lid,
The liner is adhered to the inner surface of the top wall radially inward of the pair of scores, and the outer peripheral edge portion of the liner extends downward in the radial direction and extends downward to incline the top wall. Is separated from the inner surface ,
In a state before being fitted to the mouth-neck portion of the container, the outer peripheral edge of the liner is located radially outside of the second portion of the pair of scores,
An easily openable container lid characterized by the following. An annular uppermost portion is defined on the top surface of the mouth/neck portion at the center in the radial direction, and the outer peripheral edge of the liner is 1.0 to 2 more than the annular uppermost portion of the top surface of the mouth/neck portion. .0mm is positioned radially outwardly, easy-open container lid of claim 1, wherein. A method for producing the easy-open container lid according to claim 1 or 2 ,
A shell forming step including adding machining to the metal sheet;
A synthetic resin material supplying step of supplying a synthetic resin material in a heat-melted or softened state to the inner surface of the top wall of the shell;
The synthetic resin material is embossed, and the outer peripheral edge is located radially inward of the pair of scores and adhered to the inner surface of the top wall, and the outer peripheral edge is separated from the inner surface of the top wall. A liner preformed body forming step of forming a liner preformed body in which a cylindrical hanging part extending vertically in a direction to be formed is formed,
A liner shaping step of deforming the hanging portion of the liner preform into a shape that is inclined in a direction separating from the inner surface of the ceiling wall toward the outside in the radial direction;
A method comprising: A coating having adhesive properties to the synthetic resin material is applied to one surface of the metal thin plate, and in the shell forming step, the metal thin plate is machined so that the one surface defines the inner surface of the top wall. The method of claim 3 , wherein processing is applied. The method according to claim 3 or 4 , wherein in the liner shaping step, a heated shaping tool is acted on the hanging portion of the liner preform to deform the hanging portion. In the liner shaping step, a heated primary shaping tool is caused to act on the hanging portion of the liner pre-molded body so that the inner peripheral surface of the hanging portion extends radially outward at an inclination angle α of the top wall. The inner peripheral surface of the hanging part is larger than the tilt angle α by deforming into a shape inclined in a direction away from the inner surface, and then applying a heated secondary shaping tool to the hanging part of the liner preform. 6. The method according to claim 5 , wherein the method is such that the shape is inclined outward in the radial direction at an inclination angle β in a direction away from the inner surface of the ceiling wall. The gripping piece of the shell includes a base portion integrally formed from the metal thin plate together with the top wall and the skirt wall, and a ring-shaped portion formed of a synthetic resin. In the shell forming step, the metal thin plate is machined. Processing to form the base of the gripping piece with the top wall and the skirt wall of the shell, and then molding the ring-shaped portion of the gripping piece from the synthetic resin and connecting to the base of the gripping piece. The method according to any one of claims 3 to 6 , which comprises: