CAP AND METHOD FOR MANUFACTURING CAP

A cap includes: a cap body including a top plate portion and a cylindrical skirt portion; a sealing member provided in the cap body separately from the cap body so as to face the top plate portion; a plurality of locking portions arranged in a circumferential direction in the skirt portion, the locking portions protruding inward in a radial direction of the skirt portion and supporting the sealing member; a plurality of small diameter portions arranged between the top plate portion and the locking portions of the skirt portion, the small diameter portions being respectively provided on a top plate portion side of the locking portions in the axial direction; and a plurality of large diameter portions provided adjacent to the small diameter portions in the circumferential direction and having an inscribed circle diameter larger than an inscribed circle diameter of the plurality of small diameter portions.

FIELD

The present invention relates generally to a cap for sealing a can container containing a beverage and a method for manufacturing the cap.

BACKGROUND

Conventionally, a cap for sealing a mouth portion of a can container has a configuration in which a sealing member made of a resin material that comes into close contact with the mouth portion is provided on an inner surface of a cap body. As such a cap, Jpn. Pat. Appln. KOKAI Publication No. 2004-217295 and Jpn. Pat. Appln. KOKAI Publication No. 2017-178421 disclose a technique in which a cap body and a sealing member are not mutually bonded in order to reduce cap opening torque at the time of opening the cap.

PATENT LITERATURE

SUMMARY

For the cap described above, the sealing member is engaged with a vent slit projecting inward of a skirt portion to prevent the sealing member from falling off. However, in a case where the internal pressure of the container becomes negative, the sealing member tends to adhere to the container mouth portion side, and there is a concern that the sealing member may fall off the cap body at the time of opening the cap.

On the other hand, in a case where the vent slit is formed deeply inward in a radial direction in order to sufficiently engage with the sealing member, there is a concern that a crack may occur at an end portion of the vent slit. It is also conceivable to provide the skirt portion with a recessed portion which protrudes inward of the slitless skirt portion. However, even in a case where the sealing member is engaged with the recessed portion provided in the skirt portion, there are concerns the skirt portion may be damaged if the recessed portion is formed too deeply.

It is therefore an object of the present invention to provide a cap and a method for manufacturing the cap which can reliably prevent a sealing member from falling off without damaging a skirt portion.

DETAILED DESCRIPTION

According to one aspect of the present invention, a cap includes: a cap body including a top plate portion and a cylindrical skirt portion provided on a peripheral edge portion of the top plate portion; a sealing member provided in the cap body and separately from the cap body so as to face the top plate portion; a plurality of locking portions arranged in a circumferential direction in the skirt portion, the locking portions protruding inward in a radial direction of the skirt portion and supporting the sealing member; a plurality of small diameter portions arranged between the top plate portion and the locking portions of the skirt portion, the small diameter portions being respectively provided on a top plate portion side of the locking portions in the axial direction; and a plurality of large diameter portions provided adjacent to the small diameter portions in the circumferential direction and having an inscribed circle diameter larger than an inscribed circle diameter of the plurality of small diameter portions.

According to one aspect of the present invention, a method for producing a cap includes: arranging a molded product having a top plate portion and a skirt portion integrally formed with the top plate portion via an annular and curved corner portion in a first tool having a plurality of first protrusions on an outer peripheral surface thereof, a plurality of large-diameter-portion forming portions adjacent to the first protrusions in an axial direction, and small-diameter-portion forming portions adjacent to the large-diameter-portion forming portions in a circumferential direction; and forming a plurality of recessed portions, a plurality of small diameter portions, and a plurality of large diameter portions in the skirt portion by relatively rotating the first tool and a second tool having second protrusions arranged between the adjacent first protrusions of the first tool and causing the second protrusions to enter between the adjacent first protrusions.

Hereinafter, a cap1according to an embodiment of the present invention, a method for manufacturing the cap1, and a manufacturing apparatus200for the cap1will be described with reference toFIGS.1to16.

FIG.1is a cross-sectional view schematically showing a configuration of the cap1and a can container100according to the embodiment of the present invention,FIG.2is a perspective view showing the configuration of the cap1,FIG.3is a side view showing the configuration of the cap1, andFIG.4is a cross-sectional view showing the configuration of the cap1.FIG.5is an enlarged cross-sectional view of a portion V inFIG.4showing the configuration of the cap1, andFIG.6is an enlarged cross-sectional view of a portion VI inFIG.4showing the configuration of the cap1.FIG.7is a cross-sectional view showing the configuration of the cap1taken along line VII-VII inFIG.4.

FIGS.8and9are explanatory views showing an example of a method for manufacturing the cap1.FIG.10is an explanatory view showing a configuration of an example of the manufacturing apparatus200for the cap1, andFIGS.11to13are cross-sectional views showing the example of the manufacturing apparatus200at different positions.FIG.14is a perspective view showing a configuration of a first tool211used in the manufacturing apparatus200, andFIG.15is an enlarged perspective view showing the configuration of the first tool211in the same posture as inFIG.11.FIG.16is a perspective view showing the configuration of the first tool211in a posture different from that inFIG.11.

As shown inFIG.1, the cap1is wound and compacted in a state of covering a mouth portion110of the can container100, thereby hermetically sealing the mouth portion110. First, the can container100will be described with reference toFIG.1.

As shown inFIG.1, the can container100is a so-called bottle-type container used for containing a beverage or the like. For example, the can container100is made of a metal material such as an aluminum alloy or a surface-treated steel plate having resin films laminated on both surfaces thereof. The can container100is formed in a cylindrical shape having a varied outer diameter which is smaller at one end. The can container100has a mouth portion110at the one end for discharging the contained beverage. The mouth portion110has a jaw portion111, a male screw portion112, and a curl portion113on the outer peripheral surface thereof from the bottom surface side of the can container100toward the end portion.

The jaw portion111is configured to protrude annularly. The curl portion113is formed to have a smaller diameter than the male screw portion112. The curl portion113is configured to be smaller than the inner diameter of the cap1. The curl portion113is formed by folding the end portion of the mouth portion110once or more. The curl portion113forms an opening through which the beverage contained in the can container100is discharged.

As shown inFIGS.1to6, the cap1includes a cap body11and a sealing member12provided separately in the cap body11.

The cap body11is made of a material obtained by forming a resin coating layer on a metal material such as an aluminum alloy. The cap body11is formed into a cup shape by drawing, knurling, roll-on molding, press molding or the like of the material in the form of a thin flat plate.

As shown inFIGS.1to4, the cap body11includes a disk-shaped top plate portion21and a cylindrical skirt portion22extending downward from a peripheral edge portion of the top plate portion21. In the cap body11, the top plate portion21and the skirt portion22are integrally and continuously formed by an annular and curved corner portion23.

The top plate portion21is formed in a disk shape. As shown inFIGS.1and4, the top plate portion21has a main surface formed in a planar shape. At least one of embossing and debossing may be performed on a part of the top plate portion21.

One end of the skirt portion22is continuous with the top plate portion21via the corner portion23, and the other end is open. As shown inFIGS.1to4, the skirt portion22includes a plurality of locking portions31, a plurality of vent slit portions32, a female screw portion33, a tamper evidence band portion34, and an upper annular portion35. In the skirt portion22, for example, the upper annular portion35, the plurality of locking portions31, the plurality of vent slit portions32, the female screw portion33, and the tamper evidence band portion34are sequentially formed between the end portion on the top plate portion21side and the open end portion.

A cup-shaped molded product11A composed of the top plate portion21, the cylindrical skirt portion22where the plurality of locking portions31, the plurality of vent slit portions32, the female screw portion33, and the tamper evidence band portion34are not formed, and the corner portion23is subjected to processing such as knurling molding or roll-on molding to form the plurality of locking portions31, the plurality of vent slit portions32, the female screw portion33, and the tamper evidence band portion34in the skirt part22. The female screw portion33is formed in a state in which the cap1is attached to the can container100.

The plurality of locking portions31restrict movement of the sealing member12and hold the sealing member12by the skirt portion22being recessed inward in the radial direction. The locking portion31is a recessed portion in which a slit penetrating the skirt portion22is not formed. As shown inFIG.5, the locking portion31has an upper inclined surface31awhich is inclined inward in the radial direction of the cap1and downward from the upper annular portion35in a longitudinal section, and a lower inclined surface31bwhich is inclined inward in the radial direction of the cap1and upward from the skirt portion22below the locking portion31in a longitudinal section. The plurality of locking portions31restrict the movement of the sealing member12and hold the sealing member12by locking the sealing member12to inner surfaces of the plurality of upper inclined surfaces31a.

As shown inFIG.6, the vent slit portion32includes a recessed portion32aand a vent slit32bformed in a part of the recessed portion32a. The vent slit portion32protrudes from an inner peripheral surface of the skirt portion22. The vent slit32bis a cut through which gas in the can container100is discharged at the time of opening.

For example, in the present embodiment, thirteen locking portions31are provided and four vent slit portions32are formed along the circumferential direction of the skirt portion22. The plurality of vent slit portions32are set at equal or substantially equal intervals in the circumferential direction of the skirt portion22, and the plurality of locking portions31and the plurality of vent slit portions32are set at equal or substantially equal intervals in the circumferential direction of the skirt portion22. The plurality of locking portions31are provided on the top plate portion21side (upper annular portion35side) in the axial direction of the skirt portion22with respect to the plurality of vent slit portions32.

The female screw portion33is configured to be screwed with the male screw portion112of the can container100. The female screw portion33is formed together with the can container100. That is, the female screw portion33is not formed in a finished product of the cap1before being attached to the can container100, but is formed when the cap1is integrally combined with the can container100.

The tamper evidence band portion34engages with the jaw portion111of the can container100in a direction in which the cap1moves away from the can container100and in an axial direction of the cap1. In addition, the tamper evidence band portion34has a breaking portion34a, which is broken and detached from the skirt portion22when the cap1is opened. That is, the tamper evidence band portion34is configured by forming a slit on the end portion side of the skirt portion22while leaving the breaking portion34a, and is formed into the shape of the jaw portion111of the can container100when integrally combined with the can container100, thereby engaging with the jaw portion111, in a manner similar to the female screw portion33.

The upper annular portion35is formed at a portion located between the top plate portion21and the plurality of locking portions31of the skirt portion22. For example, the upper annular portion35is formed in a part of the corner portion23. The upper annular portion35has a plurality of small diameter portions35aand a plurality of large diameter portions35bin the circumferential direction thereof. The inscribed circle diameter (inner diameter) of the plurality of small diameter portions35ais relatively smaller than the inscribed circle diameter (inner diameter) of the plurality of large diameter portions35b.

The small diameter portion35ais adjacent to the locking portion31in the axial direction of the cap1. The inscribed circle diameter (inner diameter) of the plurality of small diameter portions35ais set to be smaller than the outer diameter of the sealing member12, and the inscribed circle diameter (inner diameter) of the plurality of large diameter portions35bis set to be larger than the outer diameter of the sealing member12.

In the upper annular portion35described above, when the plurality of locking portions31are formed, the plurality of small diameter portions35aare formed by recessing portions of the upper annular portion35adjacent to the upper portions of the respective locking portions31inward in the radial direction. In the upper annular portion35, portions where the plurality of small diameter portions35aare not formed, that is, portions between the plurality of small diameter portions35ain the circumferential direction, respectively constitute the plurality of large diameter portions35b.

In the present embodiment, the plurality of vent slit portions32are set at equal or substantially equal intervals in the circumferential direction of the skirt portion22, and the plurality of locking portions31and the plurality of vent slit portions32are set at equal or substantially equal intervals in the circumferential direction of the skirt portion22. Therefore, the circumferential length of the large diameter portion35bcorresponding to the portion where the two locking portions31are adjacent in the circumferential direction of the skirt portion22is shorter than the circumferential length of the large diameter portion35bcorresponding to the portion where the two locking portions31between which the vent slit portion32is disposed are adjacent in the circumferential direction of the skirt portion22.

As shown inFIG.4, the sealing member12is formed separately from the cap body11. The sealing member12has a disk shape having an outer diameter larger than the inscribed circle diameter of the plurality of locking portions31provided in the skirt portion22of the cap body11and the inscribed circle diameter of the plurality of small diameter portions35a. The sealing member12is provided integrally with the cap body11by being engaged in the axial direction of the cap body11with the upper inclined surfaces31aof the locking portions31protruding in the radial direction from the inner peripheral surface of the skirt portion22.

As shown inFIGS.1and4to6, the sealing member12includes a disk-shaped sliding layer41and a disk-shaped sealing layer42integrally laminated on the sliding layer41. In the sealing member12, the sliding layer41and the sealing layer42are formed of different synthetic resins. In the sealing member12, the sealing layer42is integrally laminated on the sliding layer41.

For example, as illustrated inFIG.1, the sealing member12includes a flat plate portion12ain which a region in contact with the mouth portion110on the outer peripheral side is formed to be thicker than the central side, and a curved surface portion12bin which the outer surface of the outer peripheral edge on the top plate portion21side is a curved surface. In other words, the sealing member12is formed in a disk shape, and a ridge portion on the top plate portion21side is configured by a curved surface having a predetermined curvature. The sealing member12may have, for example, a configuration in which the flat plate portion12ahas a uniform thickness.

The sliding layer41is made of a resin material having a relatively higher hardness (harder) than the sealing layer42. The sliding layer41is made of a resin material having neither adhesiveness nor stickiness to the resin coating layer of the cap body11. That is, the sliding layer41is not bonded to the top plate portion21and slides on the top plate portion21in a state of being in contact with the top plate portion21.

Examples of the resin material used for the sliding layer41include olefin-based resins such as polypropylene resin and polyethylene resin, polyester-based resins such as polyethylene terephthalate, styrene-based resins, and acrylic-based resins. In the present embodiment, the sliding layer41is made of, for example, polypropylene resin. A pigment, a lubricant, a softener, and the like can be appropriately added to the resin material used for the sliding layer41. In the example of the present embodiment, the hardness of the sliding layer41is D10 to D70 in terms of the durometer D hardness according to JIS K7215.

As shown inFIGS.1and4to6, the sliding layer41is provided separately from the cap body11so as to face the top plate portion21of the cap body11. The sliding layer41is configured to be slidable with the top plate portion21of the cap body11due to the resin material that is used. The sliding layer41is formed in a disk shape. The outer diameter of the sliding layer41is smaller than the inner diameter of the skirt portion22. The outer diameter of the sliding layer41is larger than the inscribed circle diameter of the plurality of locking portions31and the inscribed circle diameter of the plurality of small diameter portions35a, and is smaller than the inscribed circle diameter of the plurality of large diameter portions35b. The outer diameter of the sliding layer41is configured to be larger than the outer diameter of the curl portion113of the mouth portion110.

As illustrated inFIGS.5and6, the sliding layer41includes, for example, a first flat plate portion41ahaving a uniform thickness and a first curved surface portion41bin which an outer surface of an outer peripheral edge on the top plate portion21side is configured by a curved surface. In addition, for example, the sliding layer41includes a protruding portion41cprovided on the sealing layer42side of the first curved surface portion41b. The first flat plate portion41ais configured to have a uniform thickness from the center of the sliding layer41to the outer peripheral side of the portion of the mouth portion110facing the curl portion113.

The first curved surface portion41bis configured such that the portion from the outer peripheral side of the portion of the mouth portion110facing the curl portion113to the outer peripheral edge gradually decreases in thickness toward the outer peripheral edge. The protruding portion41cis configured in an annular protruding shape that is inclined with respect to the axial direction of the sliding layer41and the surface direction of the top plate portion21, and is curved or inclined toward the open end portion side of the skirt portion22. The protruding portion41cgradually decreases in thickness from the first curved surface portion41btoward the distal end.

The sealing layer42is made of a resin material having a relatively lower hardness (softer) than the sliding layer41. Examples of the resin material used for the sealing layer42include an olefin-based resin, a polyester-based resin, a styrene-based resin, an acrylic-based resin, and the like, and more preferably include a blended material of a styrene-based elastomer and a polypropylene resin, a blended material of low-density polyethylene and a styrene-based elastomer, a polyester-based elastomer, and the like. The resin material used for the sealing layer42has adhesion to the resin material used for the sliding layer41. In the present embodiment, the sealing layer42is made of, for example, a blended material of a styrene-based elastomer and a polypropylene resin. A pigment, a lubricant, a softener, and the like can be appropriately added to the resin material used for the sealing layer42.

As shown inFIGS.1and4to6, the sealing layer42is integrally provided on the main surface of the sliding layer41on the side facing the mouth portion110. The sealing layer42is formed in a disk shape. The outer diameter of the sealing layer42is smaller than the inner diameter of the skirt portion22. The outer diameter of the sealing layer42is larger than the inscribed circle diameter of the plurality of locking portions31and the inscribed circle diameter of the plurality of small diameter portions35a, and is smaller than the inscribed circle diameter of the plurality of large diameter portions35b. The outer diameter of the sealing layer42is configured to be larger than the outer diameter of the curl portion113of the mouth portion110. The outer diameter of the sealing layer42is set to, for example, the same as that of the outer diameter of the sliding layer41.

As illustrated inFIGS.5and6, the sealing layer42includes a second flat plate portion42ahaving a uniform thickness, a second curved surface portion42bin which an outer surface of an outer peripheral edge on the top plate portion21side is configured by a curved surface, and a thick portion42cprovided in the second flat plate portion42a. A main surface of the second flat plate portion42afacing the curl portion113is formed as a flat surface. For example, the second flat plate portion42ahas the same diameter as the first flat plate portion41aof the sliding layer41. The second flat plate portion42aconstitutes the flat plate portion12aof the sealing member12together with the first flat plate portion41a. In the present embodiment, the first flat plate portion41aand the second flat plate portion42aare set to have the same thicknesses, for example.

The second curved surface portion42bhas, for example, a main surface flush with the main surface of the second flat plate portion42afacing the curl portion113. The second curved surface portion42bis configured such that the portion from the outer peripheral side of the portion of the mouth portion110facing the curl portion113to the outer peripheral edge gradually decreases in thickness toward the outer peripheral edge. The second curved surface portion42bis laminated on the first curved surface portion41band the protruding portion41c. The second curved surface portion42bconstitutes the curved surface portion12bof the sealing member12together with the first curved surface portion41band the protruding portion41c.

The thick portion42cis an annular protrusion protruding from the main surface of the second flat plate portion42aon the side opposite to the sliding layer41. The thick portion42cconstitutes a sealing portion which abuts the mouth portion110of the can container100. The sliding layer41may have a configuration in which a thin portion that is a recess is provided at a portion facing the thick portion42c, with the thick portion42cprotruding annularly from both main surfaces of the second flat plate portion42aso as to secure a collapse margin of the thick portion42c.

The sliding layer41and the sealing layer42are configured such that the first curved surface portion41b, the protruding portion41c, and the second curved surface portion42bare each thinner than the first flat plate portion41aand the second flat plate portion42a.

Next, a method for manufacturing the cap1configured as described above will be described with reference toFIGS.8and9.

First, a sheet-like metallic material is drawn by a shell press apparatus to form a molded product11A (step ST1). Next, the sliding layer41is molded on the top plate portion21of the molded product11A by a sliding layer forming apparatus (step ST2).

Next, the sealing layer42is molded on the sliding layer41in the molded product11A by a sealing layer forming apparatus (step ST3). Thus, the sealing member12is molded in the molded product11A.

Next, the sealing member12in the molded product11A is removed by a sealing member conveying apparatus (step ST4). Next, the plurality of locking portions31, the plurality of vent slit portions32, the tamper evidence band portion34, and the upper annular portion35are formed by a molded product processing apparatus in the molded product11A from which the sealing member12has been removed (step ST5).

Next, the sealing member12is inserted by the sealing member conveying apparatus into the molded product11A in which the plurality of locking portions31, the plurality of vent slit portions32, the tamper evidence band portion34, and the upper annular portion35are molded (step ST6). Through these steps, the cap1is manufactured (step ST7).

For example, the manufactured cap1is collected in a collection unit. When a certain number of caps1are collected, they are conveyed to a next step, i.e., an inspection and packaging step, where they are subjected to quality inspection and packaging.

Next, a method for capping the mouth portion110of the can container100with the manufactured cap1will be described. For example, the cap1is put on the mouth portion110of the can container100so that the curl portion113, which is the distal end portion of the mouth portion110of the can container100, is in contact with the sealing layer42of the sealing member12. In this state, a load is applied to the top plate portion21of the cap body11, and the skirt portion22is roll-on molded while the corner portion23is drawn downward (toward the can container100). As a result, as shown inFIG.1, the female screw portion33is formed in the skirt portion22of the cap1, and the cap1is wound and compacted to the mouth portion110of the can container100. Such a capping method is performed in a state where the can container100is filled with the beverage. In addition, for example, the can container100capped with the cap1is subjected to retort treatment depending on the content.

Next, an example of a configuration of the manufacturing apparatus200which is used in the molded product processing apparatus and molds the plurality of locking portions31, the plurality of vent slit portions32, and the upper annular portion35of the cap1in the aforementioned step ST5will be described with reference toFIGS.10to16.

InFIGS.11to13, in order to explain the combination of the first tool211and the second tool212at each position,FIG.10shows a, b, and c that define the positions in the tool211and A, B, and C that define the positions in the tool212.FIG.11shows a cross section taken along a line at a combination a-A of the tools211and212,FIG.12shows a cross section taken along a line at a combination b-B of the tools211and212, andFIG.13shows a cross section taken along a line at a combination c-C of the tools211and212.

As shown inFIGS.10to16, the manufacturing apparatus200includes the first tool211, the second tool212, and a driving device213. The manufacturing apparatus200is an apparatus that forms the plurality of locking portions31, the plurality of vent slit portions32, the tamper evidence band portion34, the plurality of small diameter portions35a, and the plurality of large diameter portions35bin the skirt portion22by performing knurling on the skirt portion22of the cap body11(the molded product11A). For example, the manufacturing apparatus200relatively rotates the first tool211and the second tool212by the driving device213to form a portion of the skirt portion22located between the first tool211and the second tool212.

As illustrated inFIGS.10to16, the first tool211includes a first base portion221, a plurality of first protrusions222, a plurality of cutter portions223, a plurality of small-diameter-portion forming portions224, a plurality of large-diameter-portion forming portions225, a first tamper-evidence-band-portion forming portion226provided on the first base portion221, and a rotary shaft227provided in the first base portion221. In the first tool211, the first base portion221and the plurality of first protrusions222are disposed in the cap body11. The first tool211is configured by combining a plurality of components.

The first base portion221is disposed in the skirt portion22of the cap body11. The first base portion221has a cylindrical shape having an outer diameter smaller than the inner diameter of the skirt portion22. The first base portion221has, for example, a hole221ainto which the rotary shaft227is inserted. The hole221ahas, for example, a key groove.

The first protrusion222has, for example, a semi-cylindrical shape whose axial direction is along the axial direction of the first base portion221or a triangular prism shape in which both side portions are curved. The plurality of first protrusions222are arranged in the circumferential direction with a predetermined distance between the adjacent first protrusions222. Here, the predetermined distance is set to a width larger than a circumferential width of a second protrusion232of the second tool212, which will be described later.

The cutter portion223is a protrusion that shears, breaks, or cuts a portion of the skirt portion22where the vent slit32bis formed, together with the second protrusion232of the second tool212. The cutter portion223is arranged between adjacent first protrusions222among the plurality of first protrusions222on one end side of each of the adjacent first protrusions222.

The small-diameter-portion forming portion224is a recess provided adjacent to the end portion side of the first protrusion222of the first base portion221in the axial direction. The large-diameter-portion forming portion225is a protrusion formed adjacent to the small-diameter-portion forming portion224in the circumferential direction. The large-diameter-portion forming portion225is provided in a range adjacent to the cutter portion223in the axial direction. The plurality of small-diameter-portion forming portions224and the plurality of large-diameter-portion forming portions225are recesses and protrusions provided in the circumferential direction at the end portion of the first base portion221.

The first tamper-evidence-band-portion forming portion226forms the skirt portion22in the shape of the tamper evidence band portion34and forms a plurality of breaking portions34aby intermittently forming slits.

The rotary shaft227is fixed to the hole221aof the first base portion221. The rotary shaft227is connected to the driving device213.

The second tool212is a tool that is disposed on the outer peripheral surface side of the skirt portion22and forms the plurality of locking portions31, the plurality of vent slit portions32, the tamper evidence band portion34, the plurality of small diameter portions35a, and the plurality of large diameter portions35bin the skirt portion22together with the first tool211. As illustrated inFIGS.10to16, the second tool212includes a second base portion231, a plurality of second protrusions232, and a second tamper-evidence-band-portion forming portion233provided on the second base portion231.

The second base portion231has, for example, an arc plate shape. For example, the outer diameter of the second base portion231is set to be larger than the outer diameter of the first base portion221and the outer diameter of the skirt portion22. The second base portion231may have a disk shape, a quarter circle shape, or a semicircle shape as long as it has an outer peripheral surface with a radius of curvature capable of suitably forming the plurality of locking portions31, the plurality of vent slit portions32, the plurality of small diameter portions35a, and the plurality of large diameter portions35btogether with the first tool211. Further, the second base portion231may be rotatable, or may be configured not to be rotated if the first base portion221is configured to be rotated.

For example, the tip of the second protrusion232is formed in a curved surface shape, and one end side in the axial direction (the top plate portion21side of the skirt portion22) is formed in a flat surface shape. In addition, the second protrusion232is formed in a shape in which the width gradually decreases toward the tip in the axial direction and the direction orthogonal to the axial direction.

As illustrated inFIG.10, the second protrusion232includes, for example, first teeth232A for forming the vent slit portions32and second teeth232B for forming the locking portions31. Here, the first teeth232A and the second teeth232B are formed in different shapes so as to suitably form the vent slit portions32and the locking portions31, respectively, but may alternatively be formed in the same shape as long as the locking portions31and the vent slit portions32can be suitably formed.

The second tamper-evidence-band-portion forming portion233forms the skirt portion22in the shape of the tamper evidence band portion34together with the first tamper-evidence-band-portion forming portion226, and forms the plurality of breaking portions34aby intermittently forming slits.

The end face of the tip of the second protrusion232enters between the adjacent first protrusions222, thereby pressing the skirt portion22to form a recessed portion. As a specific example of step ST5of the manufacturing method described above, the first tool211and the second tool212are relatively moved in a state in which the first base portion221of the first tool211is inserted into the molded product11A. Then, as illustrated inFIGS.11to13, the end faces of the tips of the second projections232sequentially enter between the adjacent first projections222, thereby pressing the skirt portion22. At this time, the end faces of the second protrusions232are located closer to the center of the first base portion221than the radially outer surfaces of the small-diameter-portion forming portions224in the radial direction of the first tool211.

For example, in a case where the cutter portion223is adjacent to the first protrusion222in the axial direction, as shown inFIG.11, the vent slit32bis formed in a part of the recessed portion by the cutter portion223and the first teeth232A of the second protrusion232during formation of the recessed portion, and the recessed portion constitutes the vent slit portion32.

In a case where the cutter portion223is not adjacent to the end portion of the first protrusion222in the axial direction, as shown inFIG.12, the recessed portion formed by the second teeth232B of the second protrusion232constitutes the locking portion31.

Further, at this time, as shown inFIG.12, the second projection232moves a portion constituting the upper annular portion35on the top plate portion21side of the skirt portion22toward the small-diameter-portion forming portion224which is a recess. As a result, a portion of the skirt portion22adjacent to the locking portion31on the top plate portion21side is drawn toward the small-diameter-portion forming portion224and plastically deformed so as to be recessed, thereby forming the small diameter portion35a. In addition, a portion adjacent to the small diameter portion35ain the circumferential direction is pressed against the large-diameter-portion forming portion225, and the large diameter portion35bis formed adjacent to the small diameter portion35a. The large diameter portion35bis formed in a portion of the upper annular portion35adjacent to the vent slit portion32.

The driving device213is a driving source that relatively rotates the first tool211and the second tool212. The driving device213rotates, for example, the rotary shaft227. The driving device213is, for example, a motor or a transmission mechanism that transmits rotation of the motor to the rotary shaft227. The driving device213rotates the first tool211in one direction.

The driving device213need only relatively rotate the first tool211and the second tool212, and may be configured to rotate the second base portion231of the second tool212instead of rotating the first base portion221via the rotary shaft227of the first tool211, or may rotate both the first base portion221and the second base portion231. For example, the driving device213may be configured to be movable between an initial position at which the cap body11is disposed on the first tool211and a molding position at which the first tool211and the second tool212are in a predetermined positional relationship to mold the cap body11.

According to the cap1configured as described above and the method for manufacturing the cap1, the skirt portion22(the upper annular portion35) between the top plate portion21and the plurality of locking portions31has the small diameter portions35ain which the inner diameter above the locking portions31is smaller than the inner diameter above the portion where the locking portions31are not formed. Thus, the metallic material that existed before formation of the small diameter portions35aat the position where the small diameter portions35aare set to be formed is drawn radially inward when the locking portions31are formed. Therefore, without damaging the skirt portion22, the locking portions31can be formed deeply inward in the radial direction, and the inscribed circle diameter of the plurality of locking portions31can be reduced. That is, the inscribed circle diameter of the plurality of locking portions31can be smaller than the outer diameter of the sealing member12. Since the sealing member12can be supported by the plurality of locking portions31, it is possible to reliably prevent the sealing member12from falling off from the cap body11.

Furthermore, by setting the inner diameter of the inscribed circle of the plurality of small diameter portions35ato be smaller than the outer diameter of the sealing member12, the inner peripheral surfaces of the small diameter portions35acome into contact with the outer peripheral edge of the sealing member12, so that the inner peripheral surfaces of the small diameter portions35aretain the sealing member12. Therefore, the cap body11can fix the outer peripheral portion of the sealing member12via the small diameter portions35ain addition to support by the plurality of locking portions31, and can more reliably prevent the sealing member12from falling off the cap body11. In addition, the sealing member12disposed in the cap body11is positioned in the radial direction by the inner peripheral surfaces of the plurality of small diameter portions35a. Therefore, when the cap1is attached to the can container100, the thick portion42cof the sealing member12reliably faces the mouth portion110of the can container100, so that the cap1can reliably seal the can container100.

As described above, according to the cap1and the method for manufacturing the cap1of the embodiment of the present invention, the plurality of locking portions31supporting the sealing member12can be formed without damaging the skirt portion22, and the locking portions31can be formed deeply. Therefore, the cap1and the method for manufacturing the cap1can reliably prevent the sealing member12from falling off the cap body11.

Note that the present invention is not limited to the embodiment described above. For example, although the numbers of the plurality of locking portions31and the plurality of vent slit portions32have been described as examples, the numbers of the locking portions31and the vent slit portions32can be set as appropriate. That is, the number of the locking portions31may be the same as the number of the vent slit portions32, or greater or lesser than the number of the vent slit portions32. In addition, the shapes of the locking portion31and the vent slit portion32can be appropriately set. In addition, the position and the opening area of the vent slit32bof the vent slit portion32can be appropriately set.

That is, as long as the sealing member12can be supported by the plurality of locking portions31, the numbers, shapes, and the like of the locking portions31and the vent slit portions32can be appropriately set depending on the shapes of the cap1and the can container100, the contents to be contained in the can container100, the internal pressure in the can container100, and the like.

That is, the present invention is not limited to the above-described embodiment, and in the practical stage, various modifications may be made without departing from the spirit of the invention. Furthermore, embodiments may be appropriately combined and implemented, and in that case, the combined effects may be obtained. Furthermore, the embodiment described above includes various inventions, and various inventions can be extracted by a combination selected from structural elements disclosed herein. For example, if the object of the invention is achieved and the advantages of the invention are attained even after some of the structural elements disclosed in connection with the embodiments are deleted, the structure made up of the resultant structural elements can be extracted as an invention.

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