JP7642385B2 - Manufacturing method of resin cap - Google Patents

Description

The present invention relates to a method for manufacturing a resin cap that is attached to the mouth of a container to close it.

A conventional resin cap that is fitted to the mouth of a container to close it is known in Patent Document 1 as a resin cap that is made up of a top lid surface (top plate portion 1), a skirt portion 2 that hangs down from the periphery of the top lid surface (top plate portion 1), and multiple ribs (bridge-forming ribs 3) protruding from the lower inner surface of the skirt portion 2, in which a cut 12 that cuts away the skirt portion 2 along the circumferential direction is formed in the portion of the skirt portion 2 where the ribs (bridge-forming ribs 3) are provided, and in which the skirt portion 2 is divided by the cut 12 into a main body portion 2a on the top lid surface (top plate portion 1) side and a band portion (pilfer-proof ring 2b) on the lower end side.

The resin cap (cap) known in Patent Document 1 has a threaded portion (screw 9) formed on the inner peripheral surface of the main body portion 2a that can be threadably engaged with the container mouth, and after being molded into a predetermined shape, a cutter 15 is used to cut from the outer peripheral side of the skirt portion 2 to a depth that does not completely cut the rib (bridge-forming rib 3), forming a notch 12, and the main body portion 2a and the band portion (pilfer-proof ring 2b) are connected by the rib (bridge-forming rib 3).

Furthermore, fins (wings 10) protruding radially inward are formed on the inner surface of the band portion (pilfer-proof ring 2b), and when the fins (wings 10) fit into the container mouth, they deform and overcome the locking ring at the container mouth, and then return to their original position below the locking ring.
As a result, after the resin cap (cap) is attached to the mouth of the container, when the main body portion 2a is rotated to open it, the band portion (pilfer-proof ring 2b) is prevented from moving upward due to interference between the fin (wing 10) and the locking ring, so that only the main body portion 2a moves upward, breaking the rib (bridge-forming rib 3), and only the main body portion 2a detaches from the mouth of the container, thereby providing a pillfer-proof function that allows the opened state to be easily confirmed visually.

In addition, a resin cap (cap C) with a locking ridge on the inner peripheral surface of the band portion (TE band T) is known from Patent Document 2.

The resin cap (cap C) known from Patent Document 2 has a top lid top surface (top wall R), a skirt wall SK hanging down from the periphery of the top lid top surface (top wall R), and a band portion (TE band T) connected to the lower end of the skirt wall SK via a bridge B.
Furthermore, after the cap C is formed into a predetermined shape, the skirt wall SK and the outer peripheral surface of the band portion (TE band T) are cut by a cap processing cutter 10 to form a slit SL.

The cap processing cutter 10 has a bridge recess 22 provided in the first cutter portion 20, so that when the entire circumference of the cap C is cut with the cap processing cutter 10, slits SL, which are the incisions cut by the first cutter portion 20, and bridges B, which are areas avoided from cutting by the bridge recess 22, are formed alternately and continuously, and the shape and number of the bridges B and slits SL can be changed by changing the spacing and length at which the bridge recess 22 is provided.
In addition, the locking protrusions are formed to protrude radially inward from the inner surface of the band portion (TE band T), and when the cap C is fitted, the elastic deformation of the band portion (TE band T) allows it to overcome the locking ring at the container mouth.However, when the cap is opened, it interferes with the locking ring and prevents the band portion (TE band T) from moving upward.In this way, only the upper part moves upward from the skirt wall SK, breaking the bridge B and detaching from the container mouth, thereby providing a pill-proof function that allows the opened state to be easily confirmed visually.

In addition, the resin cap (cap) known in Patent Document 3 has a skirt wall (upper fitting tube 3') hanging down from the top surface (top plate) of the upper lid and a band portion (lower fitting tube 3'') connected by a horizontal thin-walled portion (5).
Furthermore, an opening flange (operation piece 10) is formed on a part of the outer circumferential surface of the skirt wall (upper fitting tube 3'), and the skirt wall (upper fitting tube 3') and the band portion (lower fitting tube 3") are connected by a band plate portion (12) at a position opposite to the position where the opening flange (operation piece 10) is provided.

In the resin cap (cap) described in Patent Document 3, when the opening flange (operating piece 10) is pushed up, the horizontal thin-walled portion (5) is torn from both ends of the window (4) which is the area near the opening flange (operating piece 10) where the horizontal thin-walled portion (5) is not formed, and the skirt wall (upper fitting tube 3') moves away from the container mouth (bottle mouth 20). When the horizontal thin-walled portion (5) is completely torn away, the skirt wall (upper fitting tube 3') comes completely off and the container mouth (bottle mouth 20) opens.
At this time, since the skirt wall (upper fitting cylinder 3') is connected to the cap body (lower fitting cylinder 3'') by the strip portion (12), there is no risk of losing the skirt wall (upper fitting cylinder 3'), and the cap can be easily recapped.

Japanese Utility Model Application Publication No. 2-59154 JP 2015-188974 A Japanese Utility Model Application Publication No. 60-115861

However, there is still room for improvement in the resin caps described in the above patent documents.

In other words, when the resin cap described in Patent Document 1 is cut from the outer peripheral surface of the skirt portion using a cutter, in order to prevent deformation of the resin cap and cut evenly, the fins must be bent so as not to interfere when the inner peripheral surface of the skirt portion is held down with an inner tool, which could increase the number of manufacturing processes.
Furthermore, an increased amount of resin is required to form the fins, which may increase manufacturing costs.

In addition, in the resin cap described in Patent Document 2, the spacing and number of slits and bridges can be adjusted by the bridge recess provided in the first cutter portion of the cap processing cutter, but the circumferential position of the cap where the formation of the slits and bridges begins is random. Therefore, in the case of a cap that is opened by lifting an opening flange provided on the top lid rather than a screw cap that threads into the container mouth, there is a risk that the bridge cannot be formed in the desired position or that the bridge breaking strength when opened will be unstable depending on the position where the bridge is formed.
Furthermore, even if the bridge is pre-formed in a position that protrudes radially inward from the skirt wall like the rib of the resin cap described in Patent Document 1, and the entire circumference is cut radially outward with a cutter without providing a recess for the bridge, there is a risk that the locking protrusion will interfere with the inner tool and become deformed or damaged.

In addition, in the resin cap described in Patent Document 3, to form a thin section, such as the horizontal thin-walled section that connects the top cover and the band section, using injection molding alone, the mold must be machined more precisely, which could increase manufacturing costs.

The present invention is devised to solve these problems, and aims to provide a manufacturing method for a resin cap that has a simple configuration, can reduce the number of manufacturing steps and the amount of resin used, does not require high processing precision, and can be opened without applying a large amount of force.

The method for manufacturing a resin cap of the present invention is a method for manufacturing a resin cap having a band portion that fits into a bulge provided around a container mouth portion, a top lid that is connected to the band portion and closes the container mouth portion, and a fracture line having a plurality of bridges and slits that separate the band portion and the top lid along a circumferential direction, wherein the band portion has a circular cylindrical wall and a locking protrusion that protrudes radially inward from an inner peripheral surface of the cylindrical wall, the top lid has a top lid top surface and a skirt wall that hangs down from a peripheral edge of the top lid surface, the top lid is provided with an opening flange that protrudes radially outward beyond the skirt wall, and an upper portion of the inner peripheral surface of the cylindrical wall of the band portion and the skirt wall are connected to each other. and the lower part of the inner surface of the cylindrical wall and the skirt wall are connected by a plurality of ribs protruding inward, and a cutting groove is provided in the rib from the outer diameter side toward the inner diameter side in the radial direction, and the remaining part of the rib is the bridge, and the bridge and the slit are simultaneously formed by cutting means that makes cuts to a predetermined depth around the entire circumference in post-processing, and when the cutting means makes the cuts on the outer peripheral surface sides of the cylindrical wall and the skirt wall, a cylindrical jig is inserted into the inner peripheral surface sides of the cylindrical wall and the skirt wall, and the outer peripheral surface of the jig is formed to have the same diameter as the inner peripheral surfaces of the plurality of ribs, thereby solving the above problem.

According to the manufacturing method of a resin cap of claim 1, the bridge and slits are formed simultaneously by cutting means that makes cuts to a predetermined depth around the entire circumference of the outer peripheral surface sides of the cylindrical wall and skirt wall in post-processing, so there is no need to mold the intricate shape of the bridge using a mold, which improves production speed and suppresses increases in manufacturing costs due to the complexity of the mold structure.
In addition, when making cuts on the outer peripheral surfaces of the cylindrical wall and skirt wall with the cutting means, a cylindrical jig is inserted on the inner peripheral surfaces of the cylindrical wall and skirt wall, and the outer peripheral surface of the jig is formed with the same diameter as the inner peripheral surfaces of the multiple ribs.Therefore, even if a force that distorts the plastic cap is generated due to the pressing force when making cuts from the outer peripheral surfaces of the cylindrical wall and skirt wall with the cutting means, the inner peripheral surface of the rib is pressed by the outer peripheral surface of the jig, so distortion of the plastic cap can be prevented and cuts can be reliably made to the specified depth in the height region where the rib is located in the axial direction.
Furthermore, by making cuts at a predetermined depth around the entire circumference, it is possible to form the cut grooves and the slits at the same time, which does not increase the number of manufacturing steps.

1 is a perspective view showing a state in which a resin cap 100 according to an embodiment of the present invention is fitted onto a container mouth B. FIG. FIG. 2 is a bottom view of the resin cap 100 according to the embodiment of the present invention. A-A' cross-sectional view of the resin cap 100 according to one embodiment of the present invention. B-B' cross-sectional view of the resin cap 100 according to one embodiment of the present invention. 1 is a cross-sectional view showing a state in which the resin cap 100 according to an embodiment of the present invention is fitted onto a container mouth B. FIG. 1 is a cross-sectional view showing a state in which an upper lid 120 has been removed from a container opening B of the resin cap 100 according to an embodiment of the present invention. 4 is a cross-sectional view showing a process of forming a break line 130 in the resin cap 100 according to one embodiment of the present invention. FIG.

The following describes a resin cap 100 according to one embodiment of the present invention with reference to the drawings. Note that only the container mouth portion B of the container into which the resin cap 100 fits is shown.

The resin cap 100 is attached to the container mouth B to close the container, and as shown in Figures 1 to 4, it has a band portion 110 below the break line 130 and an upper lid 120 above the break line 130.
The band portion 110 includes a cylindrical wall 111 and a locking protrusion 112 that is provided on the inner peripheral surface of the cylindrical wall 111 and protrudes radially inward.

The longitudinal cross-sectional shape of each of the locking protrusions 112 is approximately a right-angled triangle, with an upper surface that extends radially inward at a slight downward incline, and a lower surface that is approximately arc-shaped and inclined radially outward toward the lower tip.
The locking protrusions 112 have a predetermined thickness in the circumferential direction and are not subject to significant deformation.

The top lid 120 has a top lid top surface 121, a skirt wall 123 hanging down from the periphery of the top lid top surface 121, an opening flange 122 protruding radially outward from the skirt wall 123 (in this embodiment, the opening flange 122 protrudes radially outward from the same axial height as the top lid top surface 121), and an inner ring 124 hanging down from the top lid top surface 121 radially inward from the skirt wall 123.
Furthermore, in this embodiment, a contact ring 126 that protrudes downward from the top surface 121 of the upper lid is provided between the skirt wall 123 and the inner ring 124 .
An engaging portion 125 is provided on the inner peripheral surface of the skirt wall 123 so as to protrude radially inward.

The inner circumferential surface of the upper part of the cylindrical wall 111 and the inner circumferential surface of the lower part of the skirt wall 123 are connected by a plurality of ribs 131 that protrude radially inward and extend in the vertical direction, and a slit 132 that radially penetrates the entire circumference except for the ribs 131 is arranged between the cylindrical wall 111 and the skirt wall 123, forming a fracture line 130.
In this embodiment, there are no ribs 131 within a range of 45° clockwise or counterclockwise from the circumferential center of the opening flange 122, and ten ribs 131 are arranged at other locations with circumferential spacing, and each rib 131 has an approximately rectangular shape that is long in the axial direction.
The rib 131 protrudes radially inward further than the locking protrusion 112, and at the same height as the slit 132 of the rib 131, a cutting groove 132a is formed from the radial outer diameter side to the radial inner diameter side, and a bridge 133 is formed further radially toward the radial inner diameter side of the rib 131 than the cutting groove 132a.

The inner diameters of the inner peripheral surfaces of the cylindrical wall 111 and the skirt wall 123 at the height where the ribs 131 are formed are formed uniform.
Furthermore, the outer diameter of the outer peripheral surface of the upper portion of the skirt wall 123 where the opening flange 122 is not formed is smaller than the outer diameter of the outer peripheral surface of the cylindrical wall 111 .

In addition, it is desirable to form the rib 131 so as to avoid the inner surface of the cylindrical wall 111 and the inner surface of the skirt wall 123 within an angle range of up to 45 degrees clockwise and counterclockwise, respectively, based on the circumferential center of the opening flange 122, when viewed from the center of the top cover 120.
This makes it easier to open the resin cap 100.

Here, an example of a method for forming the cut grooves 132a and the bridges 133 that constitute the fracture line 130 will be described with reference to FIG.
First, the resin cap 100 having no cut grooves 132a, which has been molded by a predetermined method, is turned over and placed so that the top surface 121 side of the upper cover is attached to the stage S.
Next, the jig T is pressed against the inner surface of the top lid surface 121 .
At this time, by making the outer circumferential surface of the jig T have the same diameter as the inner circumferential surface of the rib 131 , the outer circumferential surface of the jig T maintains contact with the inner circumferential surface of the rib 131 .

In this state, a cutter C is brought close to the outer peripheral surfaces of the cylindrical wall 111 and the skirt wall 123, and cuts are made to a predetermined depth all around the circumference to form a cut groove 132a.
At this time, even if a force that distorts the resin cap 100 is generated due to the pressing force of the cutter C, the inner surface of the rib 131 is pressed by the outer surface of the jig T, so that distortion of the resin cap 100 can be prevented, and the cutter C can form a cutting groove 132a and reliably make a cut to a specified depth in the height region where the rib 131 is located in the axial direction.
In addition, since the cutter C is brought close and cut to a predetermined depth all around the circumference, the slit 132 can be formed at the same time as the cut groove 132a is formed, and therefore no additional manufacturing steps are required.

Furthermore, by cutting the ribs 131 with the cutter C, the ribs 131 form breakable bridges 133 .
At this time, by adjusting the amount of cutting into the rib 131 in the inner diameter direction, the breaking strength of the bridge 133 can be easily adjusted.
Furthermore, the position of the rib 131 connecting the band portion 110 and the top cover 120 is determined in advance during molding, so that the rib 131 can be reliably positioned at the desired position by adjusting the mold.

Furthermore, when making the incision with cutter C, it is possible to set the depth so as not to completely penetrate cylindrical wall 111 and skirt wall 123, thereby forming a thin-film weak connection portion having a lower breaking strength than bridge 133. This makes it possible to suppress distortion of the relative positions of band portion 110 and top cover 120 even if external force is suddenly applied to resin cap 100, and also to suppress unintended breakage of bridge 133.
In addition, the weak connection portion does not have to be formed into a thin film by cutter C, but may be formed into a long, thin rib shape having a lower breaking strength than bridge 133 by adjusting the mold during molding, and one or more of these may be arranged spaced apart on the circumference, similar to rib 131.

Next, the state in which the resin cap 100 according to one embodiment of the present invention is fitted to the container mouth B and the state in which it is opened will be described with reference to Figures 5 and 6.

First, the resin cap 100 is pressed onto the container mouth B from above to fit it.
At this time, the locking protrusion 112 of the cylindrical wall 111 interferes with the bulge D of the container mouth B, but the temporary expansion of the cylindrical wall 111 causes the locking protrusion 112 to overcome the cylindrical wall 111 and move to the bottom of the cylindrical wall 111.
As a result, the band portion 110 maintains the locking protrusion 112 positioned below the bulge portion D.
Furthermore, the inner ring 124 of the upper lid 120 enters the container mouth B so as to adhere to the inner surface of the container mouth B, and proceeds downward to a position where the engaging portion 125 overcomes the protrusion E of the container mouth B, and the contact ring 126 contacts the upper end of the protrusion E of the container mouth B, completing the fitting of the resin cap 100 into the container mouth B.

When opening the resin cap 100, by applying an upward force, such as by hooking a finger on the opening flange 122, the periphery of the opening flange 122 gradually rises.
At this time, since the bridge 133 is not formed around the opening flange 122, the resistance when starting to lift the opening flange 122 can be reduced.

Furthermore, when the opening flange 122 begins to be lifted, the band portion 110 also attempts to rise together with the top cover 120. However, since the band portion 110 cannot rise above the position where the locking protrusion 112 interferes with the bulge portion D, the distance between the top cover 120 and the band portion 110 gradually increases.
At this time, the bridge 133 connecting the top cover 120 and the band portion 110 is subjected to a shearing force and gradually breaks, beginning from the position closest to the opening flange 122 .
As a result, the top cover 120 gradually separates from the container mouth B starting from the opening flange 122 side, and when the bridges 133 are all broken, the top cover 120 is completely separated from the band portion 110, completing the opening of the resin cap.

In addition, the top lid 120 is provided with a locking portion 125, so the container can be resealed by hooking the locking portion 125 onto the protruding portion E of the container mouth B.

Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the invention described in the claims.

In the above-described embodiment, the ribs are described as being formed to avoid the inner surface of the cylindrical wall and the inner surface of the skirt wall within an angular range of up to 45 degrees clockwise and counterclockwise, respectively, based on the circumferential center of the opening flange, when viewed from the center of the top cover. However, the position at which the ribs are formed is not limited to this, and for example, the ribs may be formed to avoid the angular range in which the opening flange is formed and its vicinity, or the ribs may be arranged randomly regardless of the position of the opening flange.
In addition, in the above-described embodiment, the shape of each of the ribs has been described as being approximately rectangular, elongated in the axial direction, but the shape of the rib is not limited to this, and by adjusting the formability and bridge breaking strength, the rib may have various shapes, such as a rectangular shape, elongated in the circumferential direction, a hemispherical shape, or a trapezoidal shape.

In addition, in the above-mentioned embodiment, the opening flange is described as being provided on part of the outer peripheral edge of the top surface of the upper cover, but the position at which the opening flange is formed is not limited to this, and it may be formed around the entire outer peripheral edge of the top surface of the upper cover, or may be formed to protrude from part of the outer peripheral surface of the skirt wall.
In addition, in the above-described embodiment, the locking protrusions are described as not being present at the circumferential position where the opening flange is located, as shown in Figure 2, but the locking protrusions may be arranged at the circumferential position where the opening flange is located, and further, the locking protrusions may be arranged in a ring shape in the circumferential direction.

In addition, in the above-described embodiment, the top lid is described as being completely separated from the band portion when the resin cap is opened, but the configuration of the top lid and the band portion is not limited to this, and for example, the top lid and the band portion may be connected by a hinge.
In addition, in the above-described embodiment, the upper cover is described as being provided with an engagement portion, but the configuration of the upper cover is not limited to this, and for example, the upper cover may not be provided with an engagement portion.

REFERENCE SIGNS LIST 100: Resin cap 110: Band portion 111: Cylindrical wall 112: Locking protrusion 120: Top lid 121: Top surface of top lid 122: Opening flange 123: Skirt wall 124: Inner ring 125: Locking portion 126: Contact ring 130: Breaking line 131: Rib 132: Slit 132a: Cutting groove 133: Bridge B: Container mouth portion D: Bulging portion E: Protruding portion C: Cutter T: Jig S: Stage

Claims (1)

A method for manufacturing a resin cap, the resin cap having a band portion that fits into a bulge portion provided around a container mouth, an upper lid that is connected to the band portion and closes the container mouth, and a breaking line having a plurality of bridges and slits that separate the band portion and the upper lid along a circumferential direction, comprising:
The band portion has an annular cylindrical wall and a locking protrusion protruding radially inward from an inner circumferential surface of the cylindrical wall,
The top cover has a top cover surface and a skirt wall extending downward from a periphery of the top cover surface,
The upper cover is provided with an opening flange that protrudes radially outward from the skirt wall,
an upper portion of an inner circumferential surface of the cylindrical wall of the band portion and a lower portion of an inner circumferential surface of the skirt wall are connected by a plurality of ribs protruding inwardly;
The rib is provided with a cutting groove extending from the outer diameter side to the inner diameter side in the radial direction, and a remaining portion of the rib is the bridge,
The bridge and the slit are simultaneously formed by cutting means that cuts into the outer peripheral surfaces of the cylindrical wall and the skirt wall to a predetermined depth over the entire circumference in a post-processing process;
When making cuts on the outer peripheral surfaces of the cylindrical wall and the skirt wall by the cutting means, a cylindrical jig is inserted on the inner peripheral surfaces of the cylindrical wall and the skirt wall;
A method for manufacturing a resin cap, characterized in that the outer peripheral surface of the jig is formed with the same diameter as the inner peripheral surfaces of the multiple ribs .

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