JPH085499B2 - Flange curling molded container and method for manufacturing flange curling molded container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a flange curling molding container comprising a synthetic resin container body and a lid body that seals the opening of the container body, and a foam fill. Seal (Form Fill
Seal) type flange curling molded container.

[Prior Art] A sheet-like lid for forming a molded body in which a large number of cup-shaped articles are continuously bound, filling an inner filling in the cup-shaped article, and then closing the opening of the cup-shaped article. The material is heat-welded to the flange of each cup-shaped material, and then the sheet-shaped lid material is cut off at a predetermined contour position on the flange, and the cup-shaped materials are joined together (flange part of the cup-shaped material). The so-called Form Fill Seal type molding container obtained by cutting at the boundary line)
Since each of these steps can be carried out continuously, it is a container suitable for mass production and is used as various internal filler enclosing containers.

[Problems to be Solved by the Invention] By the way, the so-called form fill seal (Form
Fill Seal) type molded containers are
Since the cup-shaped objects are cut at the continuous binding part (flange boundary line of the cup-shaped objects), the cut end surface is rough,
Especially in the case of a cup-shaped object with a large capacity such as 100 ml or more, since the thermoplastic synthetic resin sheet with a thickness of 1 mm or more is used for molding, the cut end surface of the cup-shaped object may scratch the fingertips during handling of the container. There is an inconvenience such as sticking or scratches on the lips when eating or drinking the filling material in the container.

Moreover, since the continuous binding portion of the cup-shaped material is formed by the flange portion to which the sheet-shaped lid material is heat-welded, the cut edge between the continuous binding portion of the cup-shaped material and the sheet-shaped lid material is the same as it is. It remains in the product, which increases the risk of scratching the fingertips during handling of the container and causes a loss of appearance.

Further, in order to provide the strip portion for peeling the lid body from the container body, there is a problem that the strip portion protruding from the outer peripheral edge of the flange portion must be formed in advance.

[Means for Solving Problems] The first aspect of the present invention is to provide a bottom wall portion, a peripheral wall portion rising from a peripheral edge of the bottom wall portion, and a horizontal wall extending horizontally outward from an upper edge of the peripheral wall portion. A large number of cup-shaped objects, each of which is composed of a flat flange portion and a skirt portion hanging down from the entire outer peripheral edge of the flange portion, projecting horizontally outward from the lower ends of the skirt portions of adjacent cup-shaped objects. The inner filler is filled in each cup-shaped material in the molded body that is continuously bound by the extending portion,
After heat-sealing the sheet-shaped lid material that closes the opening of the cup-shaped material to the horizontal flange portion of each cup-shaped material, separate the sheet-shaped lid material at a predetermined outer contour position on the flange portion, and perform continuous binding. Is a molded container obtained by cutting the cup-shaped objects in a horizontal direction outwardly projecting from the lower end of the skirt of the cup-shaped object, wherein the flange is on the peripheral wall of the cup-shaped object. It has a horizontal portion that is continuous with the edge and projects outward in the radial direction, and the entire outer peripheral edge of the horizontal portion is a curling portion whose cut end face is directed toward the peripheral wall portion immediately below the flange portion. This is a flange curling molding container in which a cup-shaped container body made of a sheet and a lid made of a sheet-like lid material are heat-welded at the horizontal portion of the flange portion.

The flange curling molded container of the first aspect of the present invention is a container obtained by cutting a molded product in which a large number of cup-shaped objects are bound together, but the fingertips on the cut end surface of the cup-shaped container body during handling of the container There is no risk of scratches or scratches on the lips when eating or drinking the filling material in the container, and it also has the function of ensuring reliable heat welding between the container body and the lid material. Play.

A second aspect of the present invention is a container including a cup-shaped container body and a lid that closes an opening of the cup-shaped container body, wherein the cup-shaped container body is a bottom wall portion and a bottom wall portion. It is composed of a peripheral wall part that rises from the peripheral edge and a flange part that extends outward from the upper edge of the peripheral wall part, and the flange part is continuous with the upper edge of the peripheral wall part and projects outward in the radial direction. Has a horizontal portion, and one portion in the circumferential direction of the horizontal portion is a tab portion whose outer peripheral edge is a cut end, and the outer peripheral edge in the other portion of the horizontal portion is a cut end surface. Is a curling portion having a curl configuration directed toward the peripheral wall portion immediately below the flange portion, and the cup-shaped container body and the lid are heat-welded at the horizontal portion of the flange portion. .

In the flange curling molded container of the second invention, the fingertip is scratched on the cut end surface of the cup-shaped container body during handling of the container, or the lips are damaged when eating or drinking the filling material in the container, etc. There is no fear of the above, and moreover, reliable heat welding between the container body and the lid member is ensured, and the operation of peeling the lid member from the container body can be easily performed.

A third aspect of the present invention is a bottom wall portion, a peripheral wall portion that rises from a peripheral edge of the bottom wall portion, a horizontal flange portion that extends horizontally outward from an upper edge of the peripheral wall portion, and the entire flange portion. A large number of cup-shaped objects composed of a skirt portion hanging down from the outer peripheral edge are continuously bound by an extending portion protruding horizontally outward from the lower ends of the skirt portions of adjacent cup-shaped objects. The step of obtaining a molded body, the step of filling the inside of each cup-shaped material in the molded body with an internal filler, and the sheet-shaped lid member for closing the opening of the cup-shaped material in the molded body After the process of heat-sealing to the horizontal flange part of the object and separating the sheet-like lid material at the predetermined outer contour position on the flange part, the cup-shaped objects that are continuously bound are horizontally aligned from the lower end of the skirt part of the cup-shaped object. Cutting in the extension that projects outward in the direction And a curling treatment step in which the skirt portion of each cup-shaped material and the remaining portion of the extended portion are curled toward the peripheral wall portion directly below the flange portion of the cup-shaped material. is there.

According to the method for manufacturing a flange curling molded container of the third aspect of the present invention, a flange curling molded container in which the entire upper edge of the peripheral wall portion of the cup-shaped container main body is curled can be produced with high efficiency in a continuous process. .

A fourth aspect of the present invention provides a bottom wall portion, a peripheral wall portion rising from a peripheral edge of the bottom wall portion, a horizontal flange portion extending horizontally outward from an upper edge of the peripheral wall portion, and the horizontal flange portion. A large number of cup-shaped objects composed of a tab portion whose outer peripheral edge in one part in the circumferential direction of the cut end is a cut end and a skirt portion hanging from the outer peripheral edge of the other flange portion. A step of obtaining a molded body that is continuously bound by an extending portion that protrudes outward in the horizontal direction from the lower ends of the skirt portions of adjacent cup-shaped materials, and an internal filler in each cup-shaped material of the molded body And a step of heat-sealing a sheet-shaped lid member that closes the opening of the cup-shaped object in the molded body to a horizontal flange portion of each cup-shaped object, and the sheet-shaped lid member on the flange portion. After separating at the predetermined outer contour position, Cutting the cup-shaped objects together from the lower end of the skirt of the cup-shaped object in the extending portion that protrudes outward in the horizontal direction, and the skirt portion of each cup-shaped object and the remaining portion of the extended portion The method for producing a flange curling molded container, which comprises a curling treatment step in which the curling structure is directed toward the peripheral wall portion immediately below the flange portion.

And in the manufacturing method of the flange curling molding container of this 4th invention, the flange curling molding container of this 2nd invention can be highly efficiently manufactured by a continuous process.

In the method of manufacturing the flange curling molded container and the flange curling molded container of the present invention, the molding material of the container body is, for example, a single sheet of high-impact polystyrene, polypropylene, polyethylene, polyester, or ethylene-vinyl on each of the single sheets. A multilayer sheet in which gas barrier resin layers such as an alcohol copolymer resin layer and a polyvinylidene chloride resin layer are laminated is preferable.

Further, in the flange curling molded container and the method for manufacturing the flange curling molded container of the present invention, a molded body in which a large number of cup-shaped container bodies or cup-shaped products are continuously bound is molded by, for example, a vacuum molding method or a pressure molding method. However, it is particularly preferable to use the plug-assisted pressure forming method.

In the flange curling step in the method for manufacturing a flange curling molded container of the present invention, a curling groove having an inverted U-shaped cross section in a heating jig for curling is pressed against the peripheral wall portion of the cup-shaped object and extended with the skirt portion at the bottom of the curling groove. This can be easily done by bending the rest of the installation part into a U shape, but if the cup-shaped object is cylindrical, press the heating jig while rotating the cup-shaped object or use the cup-shaped object. A uniform flange curling process can be performed by a method such as pressing the cup-shaped object while rotating it along the peripheral wall of the object.

[Examples] Specific configurations of the flange curling molded container and the method for manufacturing the flange curling molded container of the present invention will be described below with reference to the drawings.

1 and 2, a flange curling molding container 1 which is an embodiment of the first invention is a cup-shaped container body 2 made of a plug-assisted compressed air molded body of a thermoplastic synthetic resin sheet, and the cup-shaped container body 2. It is composed of a lid 3 that seals the open mouth of the container body 2.

This flange curling molding container 1 has a cup-shaped product obtained by pressure-molding a thermoplastic synthetic resin sheet filled with an internal filler, that is, a bottom wall portion and a peripheral edge of the bottom wall portion. A cup-like shape composed of a peripheral wall portion that rises up from the peripheral wall portion, a horizontal flange portion that extends horizontally outward from the upper edge of the peripheral wall portion, and a skirt portion that hangs from the entire outer peripheral edge of the flange portion. A large number of products are continuously bound from the lower ends of the skirts of the adjacent cup-shaped products at the extending portions that project outward in the horizontal direction, and the individual fillings are filled into the individual cup-shaped products, and the cups are filled. The sheet-like lid material that closes the opening of the sheet-like material is heat-welded to the horizontal flange portion of each cup-like article, the sheet-like lid material is cut off at a predetermined outer contour position on the flange portion, and the sheets are continuously bound. Cup-shaped objects From the skirt portion the lower end is obtained by cutting in the extended portion which projects horizontally outward.

The cup-shaped container body 2 made of a cup-shaped material has a bottom wall 4
And a peripheral wall portion 5 rising from the peripheral edge of the bottom wall portion 4,
The flange portion 6 extending outward from the upper edge of the peripheral wall portion 5
And the flange portion 6 is connected to the upper edge of the peripheral wall portion 5 and has a horizontal portion 7 protruding outward in the radial direction, and the end portion of the flange portion 6 is a cut end surface. The cut end face of the entire outer peripheral edge of the horizontal portion 7 is the flange portion 6.
The curling portion 8 is directed directly to the peripheral wall portion 5 immediately below.

The cup-shaped container body 2 and the lid 3 made of a sheet-shaped lid material are heat-welded at the horizontal portion 7 of the flange portion 6 of the cup-shaped container body 2.

3 and 4, a flange curling molding container 9 which is an embodiment of the second invention is a cup-shaped container body 10 made of a plug-assisted compressed air molded body of a thermoplastic synthetic resin sheet, and the cup-shaped container body 10. The container (10) is composed of a lid (33) that seals the opening.

The cup-shaped container body 10 is composed of a bottom wall portion 11, a peripheral wall portion 12 rising from a peripheral edge of the bottom wall portion 11, and a flange portion 13 extending outward from an upper edge of the peripheral wall portion 12. The flange portion 13 has a horizontal portion 14 that is continuous with the upper edge of the peripheral wall portion 12 and projects outward in the radial direction.

One portion in the circumferential direction of the horizontal portion 14 is a grip portion 15 whose outer peripheral edge has a cut end 15A, and the outer peripheral edge 16 of the horizontal portion 14 in the other portion has a cut end face as a flange. The curling portion 17 has a curl structure and extends in the direction of the peripheral wall portion 12 immediately below the portion 13.

The cup-shaped container body 10 and the lid 33 are heat-welded at the horizontal portion 14 of the flange portion 13 of the cup-shaped container body 10.

In addition, the gripping portion 15 having the cutting edge 15A at the outer peripheral edge of one portion in the circumferential direction of the horizontal portion 14 grips the lid 33 when the lid 33 is gripped and peeled from the cup-shaped container body 10. This is the part that makes it easier.

FIG. 5 and FIG. 6 show a vacuum or compressed air molded body 24 of a thermoplastic synthetic resin sheet obtained in an intermediate step of the method for manufacturing a flange curling molded container of the third invention, and the molded body.
The sheet-shaped lid member 25 that closes the opening of the cup-shaped objects 23, 23 ...
It shows a state in which the horizontal flange portions 20, 20 ... Of 23, 23.

Vacuum or compressed air molding of thermoplastic synthetic resin sheet 24
Is a bottom wall portion 18, a peripheral wall portion 19 rising from the peripheral edge of the bottom wall portion 18, a horizontal flange portion 20 extending outward in the horizontal direction from the upper edge of the peripheral wall portion 19, and the flange portion. An extension in which cup-shaped objects 23 composed of skirt portions 21 hanging down from the entire outer peripheral edge of 20 project horizontally outward from the lower ends of skirt portions 21 of adjacent cup-shaped objects 23. The part 22 is composed in a row.

FIG. 7 shows a molded product obtained in an intermediate step of the method for manufacturing a flange curling molded container according to the fourth aspect of the present invention, and the molded body shown in FIG. 5 obtained in the intermediate step of the third aspect of the invention. The corresponding molded body is shown.

That is, the molded product shown in FIG. 7 is a cup-shaped product in a vacuum or compressed air molded product of a thermoplastic synthetic resin sheet.
The structure of 26, 26 ... Has a bottom wall portion, a peripheral wall portion rising from the peripheral edge of the bottom wall portion, and a horizontal flange portion 27 extending horizontally outward from the peripheral wall portion and the upper edge. The outer peripheral edge of one part of the horizontal flange portion 27 in the circumferential direction is the cut end 28.
A large number of cup-shaped objects, each of which is composed of a strip portion 28 designated as A and a skirt portion hanging from an outer peripheral edge 29 of a flange portion other than the strip portion 28, are adjacent to each other. The shaped articles 26, 26 are composed of a structure in which they are continuously bound from the lower end of the skirt portion by an extending portion 30 protruding outward in the horizontal direction, and the other configurations are the molded body shown in the above-mentioned FIG. 5 and FIG. The configuration is exactly the same as the configuration of the corresponding part.

In the third aspect of the present invention, the sheet-like lid member 25 is formed into a cup shape after the step of heat-bonding the compressed air or vacuum formed body 24 of the thermoplastic synthetic resin sheet obtained in the above step and the sheet-like lid member 25. Predetermined outer contour positions on the horizontal flange portions 20, 20 of the objects 23, 23, that is, reference numeral (a) in FIG.
While cutting at the position indicated by,
… Cut each other within the extended portion 22 that horizontally protrudes from the lower end of the skirt portion 21 of the adjacent portion of the adjacent cup-shaped material 23, that is, at the position indicated by the symbol (B) in FIG. , Forming a flange curling molded container precursor indicated by reference numeral 31 in FIG.

Then, a heating jig is pressed against the skirt portion 21 of the cup-shaped material 23 and the remaining portion 32 of the extended portion 22 in each container precursor 31, so that the cut end surface of the peripheral wall immediately below the flange portion of the cup-shaped material 23. Curling processing is performed so as to face the direction of section 19.

In addition, in the fourth aspect of the present invention, when the cup-shaped objects are separated from each other, the inside of the extended portion 30 that protrudes horizontally from the lower end of the skirt of each cup-shaped object, that is, by the reference numeral (c) in FIG. Except for the step of cutting at the displayed position, the same steps as the corresponding steps of the third aspect of the invention are performed.

[Operation and Effect] The flange curling molded container and the method for manufacturing the flange curling molded container according to the present invention are configured as described above.

The flange curling molded container according to the first aspect of the present invention is an individual container obtained by cutting a molded body in which a large number of cup-shaped objects are bound together, but the cut end surface forming the end of the flange portion is the container body. Since it is curled toward the peripheral wall portion immediately below the flange portion, the end surface of the die cut portion is located at a hidden portion that is in close contact with the peripheral wall portion of the container body.

Therefore, according to the flange curling molded container of the first aspect of the present invention, the fingertip is scratched on the cut end surface of the cup-shaped container body during handling of the container, or the lip is rubbed when eating or drinking the filling material in the container. There is no fear of being scratched, and moreover, there are effects such as ensuring reliable heat welding between the container body and the lid member.

In the flange curling molded container according to the second aspect of the present invention, one portion in the circumferential direction of the horizontal portion of the flange portion is a grip portion formed by only the horizontal flange portion, that is, the grip portion has Since the curling part is not formed, this grip part can be used as a part to which the fingertip is applied when picking and peeling the lid body, and the flange part of the other part is the cut end surface forming the end part of the flange part. Is curled toward the peripheral wall portion directly below the flange portion of the container body, so that the end surface of the die cut portion is located at a hidden portion in close contact with the peripheral wall portion of the container body.

Therefore, according to the flange curling molded container of the second aspect of the present invention, due to the roughness of the end face of the die-cut portion of the molded container, the fingertip may be scratched during handling of the container, and the filling material inside the container may be damaged. When eating or drinking, there is no damage to the lips at the end face of the die cut part, and the actions and effects excellent in safety and handling are obtained.

Further, since the lid body is heat-welded to the horizontal portion of the flange portion of the container body, reliable heat-welding is performed between the container body and the lid body in spite of the flange curling container. , The container is sealed tightly.

Furthermore, when the container is opened, there is an action and an effect that the lid portion can be easily peeled off by the tab portion.

According to the third aspect of the present invention, adjacent cup-like objects are continuously bound by the extending portion that projects outward in the horizontal direction from the lower end of the skirt portion, and there is no connecting structure in the horizontal portion of the flange portion. By cutting the sheet-shaped lid member along a predetermined outer contour line of the horizontal portion of the flange portion, a flange curling molded container having a beautiful lid structure can be obtained in a continuous process.

In addition, the extension part that continuously binds the cup-shaped objects undergoes the curling step after cutting the cup-shaped objects together in the extension part, so that the cut end surface of the extension part is not exposed to the outside, and the appearance It is possible to obtain a flange curling molding container having the effect of holding the above in a beautiful manner in a continuous process.

Further, according to the fourth invention, the operation of the third invention,
In addition to the effect, since the tab portion is formed in advance on the horizontal flange portion during the molding of the cup-shaped object, there is no need to increase the number of special processing steps, for example, without providing an extension portion on the lid portion. It is possible to form a gripping portion which is a portion to which a fingertip for gripping and peeling the lid is applied when the lid is peeled off.

Further, according to the fourth aspect of the invention, since the knob portion is formed by using the outer peripheral edge of a part of the horizontal portion of the flange portion as a cut end, the horizontal flange portion remains as it is. Therefore, a flange curling molded container can be obtained in a continuous process, which has effects such as the reliability of thermal welding between the flange portion of the container body and the sheet-shaped lid member is not impaired by forming the tab portion. .

[Brief description of drawings]

FIG. 1 shows a first embodiment of the flange curling molding container of the first invention.
FIG. 2 is a plan view of the flange curling molding container of FIG. 1, FIG. 3 is a plan view of one embodiment of the flange curling molding container of the second invention, and FIG. Three
FIG. 5 is a cross-sectional view taken along line IV-IV of FIG. 5, and FIG. 5 shows a sheet-shaped lid member formed by heat-sealing a molded body and a sheet-shaped lid member obtained in an intermediate step of the method for manufacturing a flange curling molded container of the third invention. Fig. 6 is a plan view with half of the tape peeled off, and Fig. 6 is VI-V in Fig. 5.
FIG. 7 is a cross-sectional view taken along the line I, showing a heat-welded molded product of a molded product and a sheet-shaped lid member obtained in an intermediate step of the method for manufacturing a flange curling molded container of the fourth invention, and drawing half of the sheet-shaped lid member. FIG. 8 is a plan view peeled off, and FIG. 8 is a cross-sectional view showing a flange curling molded container precursor obtained by cutting the heat-welded molded product of FIG. 6 in units of individual cups. 1: Flange curling molding container 2: Container body 3: Lid body 4: Bottom wall part 5: Peripheral wall part 6: Flange part 7: Horizontal part protruding in the radial direction 8: Curling part 9: Flange curling molding container 10: Container body 11: Bottom wall part 12: Peripheral wall part 13: Flange part 14: Horizontal part that projects outward in the radial direction 15: Part with the outer peripheral edge of one part in the circumferential direction of the horizontal part 14 as the cut end 15A 16: Outer peripheral edge of the horizontal part 14 other than the part where the outer peripheral edge is the cut end 15A 17: Curling part 33: Lid 23: Cup 24: Molded body 25: Sheet lid 27: Flange 28: A piece with the outer peripheral edge of one part in the circumferential direction of the horizontal portion of the flange 27 as the cutting edge 28A (a): Cutting position of the sheet-like lid material (b): Cutting position of the molded body

Claims (4)

[Claims] 1. A bottom wall portion, a peripheral wall portion rising from a peripheral edge of the bottom wall portion, a horizontal flange portion extending horizontally outward from an upper edge of the peripheral wall portion, and an entire outer peripheral edge portion of the flange portion. A plurality of cup-shaped objects composed of a skirt that hangs down from each other in a molded body that is bound together by extension portions that project horizontally outward from the lower ends of the skirts of adjacent cup-shaped objects. After filling the inside of the cup-shaped material with the filling material and heat-sealing the sheet-shaped lid material that closes the opening of the cup-shaped material to the horizontal flange portion of each cup-shaped material, flange the sheet-shaped lid material. A molded container obtained by separating the cup-shaped articles at a predetermined outer contour position on the section from each other, and cutting the continuously bound cup-shaped articles in an extended section that protrudes outward in the horizontal direction from the lower end of the skirt section of the cup-shaped article. The flange on the peripheral wall of the cup. Has a horizontal portion that extends outward in the radial direction, and the entire outer peripheral edge of the horizontal portion is a curling portion whose cut end face is directed toward the peripheral wall portion immediately below the flange portion. A flange curling molding container, wherein a cup-shaped container body made of a material and a lid member made of a sheet-shaped lid material are heat-welded at a horizontal portion of a flange portion. 2. A container comprising a cup-shaped container body and a lid body which closes an open mouth of the cup-shaped container body, wherein the cup-shaped container body comprises a bottom wall portion and a peripheral edge of the bottom wall portion. It consists of a rising peripheral wall and a flange extending outward from the upper edge of the peripheral wall, and the flange is continuous with the upper edge of the peripheral wall and extends horizontally outward in the radial direction. Has a portion, and one portion in the circumferential direction of the horizontal portion is a grip portion having an outer peripheral edge of the cut end, and the outer peripheral edge of the other portion of the horizontal portion has a cut end surface of a flange. A flange curling molding container, which is a curling portion directed directly to a peripheral wall portion directly below the portion, and wherein the cup-shaped container body and the lid are heat-welded at a horizontal portion of the flange portion. 3. A bottom wall portion, a peripheral wall portion rising from a peripheral edge of the bottom wall portion, a horizontal flange portion extending horizontally outward from an upper edge of the peripheral wall portion, and an entire outer peripheral edge of the flange portion. A molded body in which a large number of cup-shaped objects composed of a skirt that hangs down from one another are continuously bound by an extending portion that projects outward in the horizontal direction from the lower ends of the skirts of adjacent cup-shaped objects. A step of filling the inside of each cup-shaped material in the molded body with an internal filler, and a sheet-shaped lid member for closing the opening of the cup-shaped material in the molded body. After the process of heat-welding to the horizontal flange part, and after separating the sheet-shaped lid material at a predetermined outer contour position on the flange part, the continuously bound cup-shaped objects are horizontally outside from the lower end of the skirt part of the cup-shaped object. Cut inside the extension that projects toward you And a curling treatment step in which the skirt portion of each cup-shaped material and the remaining portion of the extended portion are curled to direct toward the peripheral wall portion immediately below the flange portion of the cup-shaped material. Container manufacturing method. 4. A bottom wall portion, a peripheral wall portion rising from a peripheral edge of the bottom wall portion, a horizontal flange portion extending horizontally outward from an upper edge of the peripheral wall portion, and a circle of the horizontal flange portion. A large number of cup-shaped objects, each of which is composed of a tab portion whose outer peripheral edge in one part in the circumferential direction is a cut end, and a skirt portion hanging from the outer peripheral edge of the other horizontal flange portion, A step of obtaining a molded body that is continuously bound by an extending portion that protrudes outward in the horizontal direction from the lower ends of the skirt portions of adjacent cup-shaped materials, and an internal filler in each cup-shaped material of the molded body And a step of heat-sealing a sheet-shaped lid member that closes the opening of the cup-shaped object in the molded body to a horizontal flange portion of each cup-shaped object, and the sheet-shaped lid member on the flange portion. After separating at the predetermined outer contour position of the A step of cutting the cup-shaped objects present in the cup-shaped object from the lower end of the skirt portion of the cup-shaped object in the horizontal direction outwardly, and the cup-shaped object of the skirt part of each cup-shaped object and the remaining portion of the extension part And a curling treatment step in which the curling structure is directed toward the peripheral wall portion immediately below the flange portion.