JP2964359B2 - Metal container lid and weakening line forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal container lid having a circumferentially extending weakening line formed on a skirt wall, and a circumferentially extending weakening line formed on a skirt wall of the metal container lid. The present invention relates to a weakening line forming device for forming.

[0002]

2. Description of the Related Art As a container lid applied to a container such as a glass or synthetic resin bottle for food and drink, a metal container lid having a so-called pill fur proof characteristic is widely and practically used. Such a container lid is an aluminum-based alloy thin plate,
It is formed from a metal sheet such as a chromic acid-treated steel sheet or a tin sheet, and has a circular top wall and a cylindrical skirt wall hanging down from the periphery of the top wall. A sealing liner, which can be formed from an appropriate synthetic resin, is provided on the inner surface of the top wall. The skirt wall is formed with a weakening line extending in the circumferential direction, and the skirt wall is partitioned into a main portion above the weakening line and a pill fur proof hem below the weakening line. The weakening line includes a plurality of circumferentially spaced slits extending in the circumferential direction and a plurality of bridging portions located between the slits. There are cases where all the bridging portions in the weakened line are easily breakable bridging portions, and cases where one (or two or more) bridging portions are not easy breaking bridging portions but are hardly breaking bridging portions.
As used herein, the phrase "easily breakable bridging part" means a bridging part whose strength is relatively weak and which is broken when the container lid is rotated with respect to the container for opening the container. The “hard-to-break bridging part” means a bridging part whose strength is relatively strong and which is not broken when the container lid is rotated with respect to the container for opening the container. If a hard-to-break bridge is present, an axially extending score is formed on the pill fur proof skirt in connection with the hard-to-break bridge.

[0003] The above-mentioned weakening line is usually constructed as
No. 7920, JP-B-45-14396, JP-B-48-9636 or JP-B-58-15205.
It is formed by a weakening line forming device of the form disclosed in the official gazette. Such a weakened line forming apparatus has an arcuate or circular outer blade, and a substantially rectangular notch is formed on the outer blade at intervals corresponding to the bridging portion.
The skirt wall of the container lid is rolled relative to such an outer blade, whereby the affected portion of the skirt wall is displaced radially inward to generate a shearing action, and thus the slit is generated. . At the boundary between the slit and the bridge, the skirt wall is also sheared axially over some length, so that the bridge has a slight axial length.

The above-mentioned container lid is applied to a container in which an external thread and a locking jaw located below the external thread are formed on the outer peripheral surface of the mouth and neck. When a container lid is attached to the mouth and neck of the container to seal the mouth and neck, the container lid is fitted to the mouth and neck and a pressing force is applied to the outer surface of the top wall of the container lid, and the sealing liner is closed. Close the upper end of the neck. While maintaining such a state, a female thread is formed on the main part of the skirt wall of the container lid along the male thread of the mouth and neck, and the lower end of the skirt wall of the container lid, that is, a pill fur proof hem. The lower end of the part is bent inward and locked on the locking jaw of the mouth and neck. When opening the mouth and neck of the container, the container lid is rotated in the opening direction. Thus, the female thread of the container lid is moved along the male thread of the mouth and neck, and thus the container lid is raised with respect to the mouth and neck. However, the pill fur proof hem of the container lid is locked by the locking jaws of the mouth and neck and thus is prevented from rising, thus creating considerable stress on the line of weakness, and more particularly its bridge. Thus, the brittle bridging part in the weakened line is broken. If all of the bridges are easily breakable bridges, this separates the pill fur proof skirt from the main portion of the skirt wall. If the bridging portion includes a hard-to-break bridge portion, the hard-to-break bridge portion is maintained without breaking, and the score extending in the axial direction at the pill fur proof hem is broken, The proof hem is opened from the endless annular form to the end band. Thereafter, the pill fur proof hem is left on the mouth and neck (when all the bridging portions are easily breakable bridging portions) or continues to be connected to the main portion of the skirt wall through the hard breaking bridging portion. The container lid is detached from the mouth and neck with the pill fur proof hem attached, and the mouth and neck are opened. When resealing the mouth and neck by reattaching the container lid to the mouth and neck of the container, in the case of a container lid in which the pill fur proof hem is connected to the main part of the skirt wall via the hard-to-break bridging portion Further pulls the pill fur proof hem to break the hard-to-break bridging portion, thereby separating the pill fur proof hem from the main part of the skirt wall.

[0005]

However, the conventional container lid of the above-described form breaks the easily breakable bridge when opening the mouth and neck of the container, or hardly breaks the bridge after opening. Ruptures, the bridging portion is broken like a saw blade, and a sharp rupture residue projecting downward from the main portion of the skirt wall is generated. If a consumer's finger or the like accidentally touches such a sharp remaining portion, there is a high possibility of damage.

In order to solve the above problem, Japanese Patent Application Laid-Open No. 2-191163 proposes that a bridging portion extending slightly in the axial direction be bent along the upper edge thereof. I have. When the bridge is subjected to such bending, the bridge will be broken along its upper edge, thus avoiding the formation of sharp fracture remnants. However, particularly in an easily breakable bridge portion, if sufficient bending is performed along the upper edge to surely generate a break, the bending portion itself breaks the bridge portion, or the container lid is broken. When the is attached to the mouth and neck of the container, the bridging portion tends to be broken. Therefore, in order to manufacture a container lid as desired, it is necessary to control or manage the degree of processing finely to make processing errors and the like in bending processing extremely fine, which leads to a reduction in manufacturing speed and an increase in manufacturing cost. I will attach it.

The present invention has been made in view of the above-mentioned circumstances, and a technical problem thereof is to improve a form of a weakening line formed on a skirt wall of a metal container lid, thereby reducing a manufacturing speed or manufacturing cost. Without the accompanying increase in
Solving the above-mentioned problem by preventing at least the easily breakable line in the weakened line from being broken like a saw blade, so that at least the breakable bridging portion does not generate a sharp breakable residue. It is.

Another technical object of the present invention is to provide an improved weakening line forming apparatus capable of forming the above-described improved weakening line on a skirt wall of a metal container lid.

[0009]

In the conventional weakening line of the container lid, the radial displacement between the upper part and the lower part of the slit is made constant over the entirety of the slit. In the container lid, in order to achieve the above technical problem, the amount of radial displacement between the upper part and the lower part of the slit at least on both circumferential sides of the easily breakable bridge is gradually increased toward the easily breakable bridge. Let it decrease.

That is, according to the present invention, there is provided a top surface wall and a cylindrical skirt wall hanging down from the periphery of the top surface wall, and the skirt wall is provided with a weakening line extending in the circumferential direction. The weakening line comprises a plurality of circumferentially spaced slits extending in the circumferential direction and a plurality of bridging portions located between the slits, each of which has an upper portion thereof and The lower portion is formed by displacing and shearing the lower portion in the radial direction, and at least some of the plurality of bridging portions are the easily breakable bridging portions. Wherein the amount of radial displacement between the upper portion and the lower portion of the slit is gradually reduced toward the easily breakable bridge portion on both circumferential sides of the portion. .

It is preferable that the amount of radial displacement between the upper portion and the lower portion of the slit at least at both ends in the circumferential direction of the easily breakable bridge portion is zero.

Further, in the present invention, in order to form the weakened line of the above-described embodiment, the outer blade of the weakened line forming device is provided with both side portions of the notch formed at an interval corresponding to the bridging portion. At least the notch relating to the easily breakable bridging portion is formed from a conventional substantially straight form in the radial direction so as to be inclined toward the outside in the radial direction on both sides in the circumferential direction.

That is, according to the present invention, a metal container lid having a top wall and a tubular skirt wall hanging down from the periphery of the top wall is circumferentially spaced from the metal container lid. A plurality of extending slits and a plurality of bridging portions located between the slits, and at least some of the plurality of bridging portions form a circumferential weakening line that is an easily breakable bridging portion. And a notch corresponding to the bridging portion is provided with an arcuate or circular outer blade arranged at an interval, the skirt wall of the container lid being relatively to the outer blade. In the weakening line forming device for rolling the affected portion of the skirt wall inward in the radial direction, the outer blade is rolled, and the outer blade is provided on both circumferential sides of the notch corresponding to the easily breakable bridge portion of the outer blade. Extends radially outward on both sides in the circumferential direction Slope portions are formed, weakening line forming device is provided, characterized in that.

[0014]

In the weakening line of the metal container lid according to the present invention, the amount of radial displacement between the upper part and the lower part of the slit is gradually reduced at least on both circumferential sides of the brittle bridging part. There is virtually no or very little axial shearing of the skirt wall at the boundary between the easily breakable bridge and the slit, and the axial length of the easily breakable bridge is substantially zero to significantly smaller. Due to this, the easily breakable bridging portion is stably broken substantially horizontally along the slit, that is, along the lower edge of the main portion of the skirt portion, so that no sharp break residue is generated. .

The weakening line in the container lid according to the present invention is obtained by improving the outer blade of the conventional weakening line forming apparatus in the shape of the notch formed at an interval corresponding to the bridging portion. Formed by the weakening line forming apparatus. Such a weakening line forming device may be obtained by improving only the shape of the notch in the outer blade of the conventional weakening line forming device, and therefore, without reducing the production speed and increasing the production cost, The required weakening line can be formed in the skirt wall.
Improvements added to the shape of the notch in the outer cutter, that is, the configuration in which both sides in the circumferential direction of the notch extend so as to be inclined to both sides in the circumferential direction, also contribute to extending the life of the outer cutter. In conventional outer blades, there are sharp corners on both outermost sides of the notch, and it is not rare that damage is generated at such sharp corners,
When the shape of the notch in the outer cutter is improved as described above, the existence of sharp corners is avoided, and the risk of damage to the outer cutter is significantly reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings.

Referring to FIG. 1, the illustrated container lid 2, which can be formed from any suitable metal sheet, such as an aluminum-based alloy sheet, a chromic acid-treated steel sheet, or a tin sheet, has a circular top wall 4 and And a cylindrical skirt wall 6 depending from the periphery of the top wall 4. At the lower part of the skirt wall 6 there is an annular bulge 8 which is somewhat bulged in the radial direction, on which a weakening line 10 extending in the circumferential direction is formed. The weakening line 10 divides the skirt wall 6 into a main portion 12 above and a pill fur proof hem portion 14 below. The weakening line 10 itself includes a plurality of slits 16 extending in the circumferential direction at intervals in the circumferential direction, and a plurality of bridging portions 18 and 20 located between the slits 16. The plurality of bridging portions 18 and 20 include one hard-to-break bridging portion 20 having a relatively large circumferential width. is there. Such a weakening line 10 will be described later in more detail. Pill fur proof skirt 14 of skirt wall 6
A score (a weakening line formed by reducing the material thickness) 22 extending in the axial direction from one circumferential end of the hard-to-break bridging portion 20 in the weakening line 10 to near the lower end of the pill fur proof hem 14 is formed. Have been. At the upper end of the main portion 12 of the skirt wall 6, an uneven portion 24 for preventing slippage is provided. An annular groove 26 is formed below the concave / convex portion 24. A sealing liner 28 that can be molded from an appropriate synthetic resin is provided on the inner surface of the top wall 4. The sealing liner 28 has a disk shape as a whole, and an annular sealing portion 30 having two concentric sealing ridges is formed on a peripheral portion thereof.

Thus, the above-described configuration of the illustrated container lid 2 is already known and does not constitute a novel feature improved in accordance with the present invention, and therefore a detailed description of such a configuration is not provided. Omitted.

FIG. 2 shows an outer blade member 32 used in a weakening line forming apparatus for forming the score 22 together with the weakening line 10 on the skirt wall 6 of the container lid 2. An outer blade 34 extending in an arc shape is formed at the upper end of the outer blade member 32. The outer blade member 32 is disclosed in JP-B-43-17920 and JP-B-45-1439.
No. 6 or Japanese Patent Publication No. 48-9636 is installed in a weakening line forming apparatus of the type disclosed in Japanese Patent Publication No. 48-9636. In this weakening line forming apparatus, the skirt wall 6
Are rolled along the outer cutter 34, during which the outer cutter 34 cooperates with the inner cutter to form the weakening line 10 and the score 22.
In the weakening line forming apparatus, prior to forming the weakening line 10 and the score 22, the formation of the annular bulging portion 8 in the skirt wall 6 of the container lid 2 is also performed by a suitable tool (not shown). If desired, the formation of the weakening line 10 and the score 22 and the formation of the annular bulge 8 can be performed substantially simultaneously. The description of the configuration of the weakened line forming apparatus itself is left to the above-mentioned publication, and is omitted in this specification. The outer cutter 34 has a circumferentially spaced 9
Notches 36 and 38 are formed. These cutouts 36 and 38 are arranged corresponding to the bridging portions 18 and 20 in the weakening line 10 to be formed in the skirt wall 6 of the container lid 2. Eight notches 36 correspond to the easily breakable bridging portion 18, and one notch 38 corresponds to the hard-to-break bridging portion 20. Referring to FIG. 3 together with FIG. 2, in the conventional outer cutter, each of the notches 36 is rectangular as shown by a two-dot chain line in FIG. 3. It is important that the portion is formed with an inclined portion 40 that extends inclining radially outward on both sides in the circumferential direction. The circumferential width of the notch 38 corresponding to the hard-to-break bridge portion 20 is set to be considerably larger than the circumferential width of the notch 36 corresponding to the easy-to-break bridge portion 18. As clearly shown in FIG. 4, an inclined portion 42 is formed at one end of the notch 38 corresponding to the hard-to-break bridging portion 20 so as to be inclined outward in the circumferential direction toward the outside in the radial direction. In the embodiment shown, the working area 45 on the outer blade 34 is the skirt wall 6 of the container lid 2.
And one end of the hard-to-break bridging portion 20 is defined by the inclined portion 42 of the notch 38, while the other end is defined by the upstream end of the outer cutter 34. Therefore, the other end of the notch 38 is functionally
4 defined by the upstream end. Therefore, an inclined portion 44 that is inclined toward the outside in the radial direction toward the downstream side is also formed at the upstream end of the outer cutter 34. Inclined part 4 for radial direction
The inclination angle α of 0, 42 and 44 is preferably 30 to 60 degrees. If desired, ramps 40, 42 and 4
By applying so-called rounding processing to both ends (radially inner end and outer end) of 4, such a portion can be made to have a smooth arc shape.

As clearly shown in FIG. 4, the outer blade member 32 is associated with the notch 38 corresponding to the hard-to-break bridging portion 20.
, A bending tool piece 46 and a score forming tool piece 48 are provided. Bending tool piece 46 and score forming tool piece 48
Is aligned with the upper end of the outer cutter 34. At the upper end of the bending tool piece 46, a ridge 50 having a substantially hemispherical cross section is provided.
Are formed. The outer peripheral surface of the ridge 50 is located radially inward of the outer peripheral surface of the outer cutter 34 by a slight length that may be, for example, 0.25 mm. A ridge 52 extending in the vertical direction is formed at the upstream end of the score forming tool piece 48. The protrusion 52 has an immersion portion 53 which is immersed in an arc corresponding to the bulge of the annular bulge portion 8 in the skirt wall 6 of the container lid 2. The cross-sectional shape of the ridge 52 is substantially trapezoidal. The ridge 52 protrudes in the radial direction beyond the outer peripheral surface of the outer cutter 34 by a slight length, which may be, for example, 0.13 mm. If desired, the bending tool piece 46 and the score forming tool piece 48 can be formed integrally with the outer blade member 32.

When the skirt wall 6 of the container lid 2 is rolled along the outer blade 34, a slit is formed in the skirt wall 6 by the action of the outer blade 34 cooperating with the inner blade 54, as shown in FIG. 16 are formed. Specifically, the skirt wall 6
The outer blade 34 acts on the lower part of the annular bulging portion 8 to be displaced radially inward, thereby generating a shearing action between the upper part and the lower part of the annular bulging part 8 to form the slit 16. I do. In the notch 36 of the outer cutter 34, FIG.
As shown, the outer blade 34 does not apply a shearing action to the annular bulge 8 of the skirt wall 6, so that the brittle bridging portion 18 remains. As described above, since the inclined portions 40 are formed on both sides in the circumferential direction of the notch 36, FIG.
As clearly shown in the figure, on both sides in the circumferential direction of the easily breakable bridging portion 18, the radially inward displacement of the lower portion of the formed slit 16 is gradually reduced toward the easily breakable bridging portion 18. . At both ends of the easily breakable bridging portion 18, it is preferable that the radially inward displacement amount is set to substantially zero. Conventionally, the inclined portion 40 is not formed in the notch 36, and therefore, as clearly shown in FIG. 10, the lower portion of the slit 16 at both ends of the easily breakable bridge portion 18 has a considerable radius. In addition to the slits 16 displaced inward in the direction and therefore extending in the circumferential direction, shear lines 56 extending in the axial direction are formed at both ends of the easy-to-break bridging portion 18, and the easy-to-break bridging portion 18 is slightly Have a length.

Even in the notch 38 of the outer cutter 34, no shearing action is formed on the annular bulging portion 8 of the skirt wall 6, so that the hard-to-break bridging portion 20 remains. In the illustrated outer cutter 34, as described above, the inclined portion 42 is formed at one end of the notch 38 and the inclined portion 44 is also formed at the upstream end of the outer cutter 34.
Also at both ends of the zero, the radially inward displacement of the lower portion of the formed slit 16 is gradually reduced toward the hard-to-break bridge portion 20, similarly to the both ends of the easily breakable bridge portion 18. 7, the ridge 52 of the score forming tool piece 48 acts on the skirt wall 6, and the skirt wall 6 extends axially downward from one end of the difficult-to-break bridging portion 20, as clearly shown in FIG. Score 22 extending to the bottom of 6
Is formed. In addition, as clearly shown in FIG. 8, the ridge 50 of the bending tool piece 46 acts on the bulging portion 8 of the skirt wall 6 to slightly displace the lower portion of the difficult-to-break bridging portion 20 radially inward. Then, the hard-to-break bridging portion 20 is subjected to bending along the weakening line 10.

FIG. 11 shows a state where the container lid 2 of FIG. 1 is applied to the mouth and neck of the container. The mouth and neck portion 58 of the container which can be formed of glass or a suitable synthetic resin has a substantially cylindrical shape, and has an external thread 60 and an external thread 6 on its outer peripheral surface.
A locking jaw 62 located below the zero is formed. In order to seal the mouth and neck 58 by attaching the container lid 2 to the mouth and neck 58, the container lid 2 is fitted to the mouth and neck 58 and the container lid 2 A pressing force is applied to the outer surface of the top wall 4 so that the annular sealing portion 30 of the sealing liner 28 is closed by the mouth and neck portion 58
Close to the upper edge of the. Then, while maintaining such a state, along the male thread 60 of the mouth-neck portion 58, the main portion 12 of the skirt wall 6 of the container lid 2 and more specifically, the region below the annular groove portion 26 (FIG. 1). An internal thread 64 is formed. In addition, the lower end portion of the pill fur proof hem portion 14 is bent inward in the radial direction so as to be locked on the locking jaw 62 of the mouth and neck portion 58.

In order to open the mouth and neck 58 of the container, the container lid 2 is rotated in the opening direction, ie, counterclockwise as viewed from above in FIG. Then, the container lid 2 is raised with the rotation by the cooperation of the male thread 60 and the female thread 64. However, pilfer-proof bottom portion 14 extending due to its lower portion is engaged with the locking jaw 62, can not be increased freely, thus the weakening line 10 and the axial extending circumferentially A considerable stress is generated in the existing score 22. Then, the easily breakable bridging portion 18 in the weakened line 10 is broken by the stress, and the score 22 is broken, and the endless annular pill fur proof hem portion 14 is opened in an end strip shape as shown in FIG. .
Thereafter, the entire container lid 2 is freely lifted up with rotation and detached from the mouth-neck portion 58, and thus the mouth-neck portion 58 is opened.

Thus, in the improved container lid 2 in accordance with the present invention, the axially extending shear lines 56 (FIG. 10) are substantially absent or present on both sides of the easily breakable bridge 18. Significantly shorter and therefore the weakening line 10
The easy-to-break bridging portion 18 at
That is, it is stably broken substantially horizontally along the lower edge of the main portion 12 of the skirt wall 6. Therefore, the main part 1 of the skirt wall 6
There is no generation of a sawtooth-shaped broken residue projecting downward at the lower edge of 2.

[0026] One Dan opened the container of the mouth-and-neck portion 58 of the container lid 2
If it is desired to temporarily reseal by
By pulling the pill fur proof hem 14, the hard-to-break bridging portion 20 remaining without being broken is broken,
Thus, the pill fur proof hem 14 is removed from the skirt wall 6 of the container lid 2. Then, the container lid 2 from which the pill fur proof hem 14 has been removed is fitted to the mouth and neck 58, and the female thread 64 of the container lid 2 is screwed to the male thread 60 of the mouth and neck 58. The axially extending shear lines 56 (FIG. 10) are also substantially absent or very short, if any, at both ends of the hard-to-break bridge 20, and the hard-to-break bridge 20 is also slightly bent along the line 10. Due to the processing, the break of the hard-to-break bridge portion 20 is also generated along the weakening line 10, that is, along the lower edge of the main portion 12 of the skirt wall 6. Accordingly, a saw-tooth-shaped broken remaining portion protruding downward at the lower edge of the main portion 12 of the skirt wall 6 due to the breakage of the hard-to-break bridge portion 20 does not occur.

EXPERIMENTAL EXAMPLE A container lid having a nominal outer diameter of 28 mm as shown in FIG. 1 was formed by using an aluminum-based alloy thin plate having a thickness of 0.23 mm. The sealing liner was formed by embossing polyethylene on the inner surface of the top wall. The circumferential width of the easily breakable bridge was 0.71 to 0.74 mm, and the circumferential width of the hard breakable bridge was 2.95 mm. Inclination angle α of the inclined part of the outer blade installed in the weakening line forming device
Was 45 degrees. FIG. 13 is a micrograph (approximately 37 times magnification) of the vicinity of an easily breakable bridge portion in the formed container lid.
It is.

FIG. 1 of a container made of polyethylene terephthalate
The container lid was attached to the mouth and neck in the form shown in FIG. 1 in the manner described with reference to FIG. Thereafter, the easily breakable bridging part and the score in the weakened line were broken in the manner as shown in FIGS. 11 and 12, and the cervix was opened. FIG. 14 is a photomicrograph (approximately 37 times magnification) of the vicinity of the ruptured bridging portion that has been broken. As can be clearly understood from FIG. 14, the rupturable bridging portion is substantially horizontal along the weakening line. And there was no saw-blade residue remaining protruding downward from the lower edge of the main part of the skirt wall. In addition, the pilfer proof hem was pulled to break the hard-to-break bridging portion, but the hard-to-break bridging portion also did not leave a saw blade-shaped break remaining protruding from the lower edge of the main portion of the skirt wall, so that the bridging line was weakened. Along a substantially horizontal line.

COMPARATIVE EXPERIMENTAL EXAMPLE For comparison, the outer cutter provided in the weakening line forming apparatus was formed in the same manner as in the above experimental example except that the inclined portion was not formed and the notch was substantially rectangular. A container lid was formed.
FIG. 15 is a photomicrograph (approximately 37 times magnification) of the vicinity of an easily breakable bridge portion in the formed container lid. As can be clearly understood from FIG. 15, an axially extending shear line was generated at both ends of the easily breakable bridge, and the length of the shear line was 0.30 mm.

Then, substantially in the same manner as in the above experimental example,
A container lid was attached to the mouth and neck of the container, and then the easily breakable bridging portion and the score in the weakening line were broken to open the mouth and neck. FIG. 16 is a photomicrograph (approximately 37 times magnification) of the vicinity of the easily broken bridge portion that has been broken. As can be clearly understood from FIG. 16, the easily breakable bridging portion was broken like a saw blade, and a saw blade-like broken residue projecting from the lower edge of the main portion of the skirt wall was generated.

[0031]

The improved container lid according to the present invention, despite being manufactured without the attendant reduction in manufacturing speed or increase in manufacturing cost, has an undesirable saw blade shape due to the breakage of the brittle bridge. This has the special effect that the generation of a residual fracture is reliably avoided. Further, the weakening line forming apparatus of the present invention can manufacture the improved container lid as described above, and furthermore, the outer blade has a longer service life than the conventional one.

[Brief description of the drawings]

FIG. 1 is a side view, partially in section, of a preferred embodiment of a container lid constructed in accordance with the present invention.

FIG. 2 is a plan view showing a preferred embodiment of an outer blade member provided in the weakening line forming apparatus used for forming the container lid of FIG.

FIG. 3 is a partial slope view showing a cutout corresponding to an easily breakable bridge portion in the outer blade of the outer blade member of FIG. 2;

FIG. 4 is a partial slope view showing a cutout corresponding to a hard-to-break bridge portion in the outer blade of the outer blade member of FIG. 2;

FIG. 5 is a partial sectional view showing a shearing action of an outer blade in the weakening line forming device of FIG. 2;

FIG. 6 is a partial cross-sectional view showing generation of an easily breakable bridge portion due to a notch of an outer blade in the weakening line forming apparatus of FIG. 2;

FIG. 7 is a partial cross-sectional view showing an operation of a score forming tool piece of an outer blade member in the weakening line forming device of FIG. 2;

FIG. 8 is a partial cross-sectional view showing the operation of a bending tool piece of the outer blade member in the weakening line forming device of FIG.

FIG. 9 is a partial slope view showing the vicinity of an easily breakable bridging portion in a weakening line of the container lid of FIG. 1;

FIG. 10 is a partial slope view showing the vicinity of an easily breakable bridging portion in a conventional container lid weakening line.

11 is a side view partially showing a cross section of a state where the container lid of FIG. 1 is attached to the mouth and neck of the container.

FIG. 12 is a side view showing a state where the container lid of FIG. 11 is detached from the mouth and neck of the container.

FIG. 13 is a micrograph showing the vicinity of an easily breakable bridging portion in a weakening line of a container lid formed in an experimental example.

FIG. 14 is a micrograph showing a rupture state of an easily ruptured bridging portion in a weakening line of the container lid of FIG.

FIG. 15 is a photomicrograph showing the vicinity of an easily breakable bridging portion in a weakening line of a container lid formed in a comparative experimental example.

FIG. 16 is a photomicrograph showing a rupture state of an easily ruptured bridging portion in the weakening line of the container lid of FIG.

[Explanation of symbols]

 2: container lid 4: top wall 6: skirt wall 10: weakening line 12: main part of the skirt wall 14: pill fur proof skirt 16: slit 18: easily breakable bridge 20: hard break bridge 22; score 32 : Outer blade member 34: Outer blade 36: Notch in outer blade (corresponding to easily breakable bridging portion) 38: Notch in outer blade (corresponding to hard-to-break bridging portion) 40: Inclined portion 42: Inclined portion 44: Inclined portion 46 : Bending tool piece 48: Score forming tool piece 54: Inner blade 56: Axial shear line (conventional container lid) 58: Container neck and neck

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 53-108553 (JP, U) Japanese Utility Model Showa 61-175144 (JP, U) Japanese Utility Model Showa 60-113137 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) B65D 39/00-55/16

Claims (10)

(57) [Claims] 1. A top surface wall and a cylindrical skirt wall hanging from a peripheral edge of the top surface wall, wherein the skirt wall is provided with a weakening line extending in a circumferential direction, and the weakening line is provided in a peripheral direction. It comprises a plurality of slits extending in the circumferential direction at intervals in the direction and a plurality of bridging portions located between the slits, each of which has an upper portion and a lower portion extending in the radial direction. It is formed by displacing and shearing, and at least some of the plurality of bridging portions are in a metal container lid which is an easily breakable bridging portion. A metal container lid, wherein a radial displacement between an upper portion and a lower portion of the slit is gradually reduced toward the brittle bridging portion. 2. The metal container lid according to claim 1, wherein the amount of radial displacement between the upper part and the lower part of the slit at both circumferential ends of the brittle bridging part is zero. 3. The metal container lid according to claim 1, wherein each of the slits is formed by forcibly shearing a lower portion of the slit radially inward with respect to an upper portion thereof. 4. At least one of the plurality of bridging portions is a hard-to-break bridging portion, and the amount of radial displacement between the upper portion and the lower portion of the slit on both circumferential sides of the hard-to-break bridging portion is also reduced. are caused to decrease gradually toward the flame fracture bridging portion, a metallic container closure according to any one of claims 1 to 3. 5. The metal container lid according to claim 4, wherein the amount of radial displacement between the upper part and the lower part of the slit is zero at both ends in the circumferential direction of the hard-to-break bridging part. 6. The metal container lid according to claim 4, wherein the hard-to-break bridging portion is subjected to bending along the weakening line. 7. A skirt wall of a metal container lid having a top wall and a cylindrical skirt wall hanging down from a periphery of the top wall,
A plurality of slits extending circumferentially at intervals in the circumferential direction and a plurality of bridging portions located between the slits, and at least some of the plurality of bridging portions are easily breakable bridges. To form a circumferential weakening line that is an entanglement,
An arcuate or circular outer blade in which notches corresponding to the bridging portions are arranged at intervals, wherein the skirt wall of the container lid is rolled relative to the outer blade. A weakening line forming device for displacing an affected portion of the skirt wall inward in the radial direction, wherein the outer blade has radially outer portions on both circumferential sides of the notch corresponding to the easily breakable bridging portion of the outer blade. A weakened line forming device, wherein a slanted portion is formed that is slanted toward both sides in the circumferential direction toward the side. 8. At least one of the bridging portions is a hard-to-break bridging portion, and both sides in the circumferential direction of the notch corresponding to the hard-to-break bridging portion in the outer cutter are also radially outwardly directed. The weakened line forming apparatus according to claim 7, wherein an inclined portion extending on both sides is formed. 9. The inclined portion of the notch has a radius of 3 degrees.
9. The weakened line forming apparatus according to claim 7, wherein the inclined line forming apparatus is inclined at an inclination angle of 0 to 60 degrees. 10. A notch corresponding to the hard-to-break bridge portion of the outer cutter is provided with a bending tool piece for bending the hard-to-break bridge portion along the weakening line.
The weakening line forming apparatus according to claim 8.