JP7585753B2 - Can Lids - Google Patents

Description

The present invention relates to a can lid that is fastened to the open end of a can body.

2. Description of the Related Art As shown in Patent Document 1, a stay-on-tab type can lid for a beverage can is known in which the drinking spout can be opened with the tab attached to the can lid body.
In a can lid equipped with this tab, the tab is attached by a rivet, and by pulling up the lifting part of the tab, the vicinity of the rivet becomes the fulcrum and the tab nose (the tip of the tab) becomes the point of action, pressing and sinking into the opening surrounded by the score on the panel surface, breaking the score and opening the opening. At this time, the start end and the end end of the score are separated, so that the opening is pushed into the beverage can without separating from the can lid, and the can is opened.

In recent years, however, there has been an increasing demand for improved pourability of the contents. In the can lid described in Patent Document 1 as a can lid that improves pourability, if a line that passes through the center of the rivet and is parallel to the longitudinal direction of the tab is taken as a reference line, the opening is formed so that the maximum width in the direction perpendicular to the reference line is greater than the length on the reference line, and the center of the maximum width is positioned offset from the reference line toward the hinge section, and one end of the tab is formed in an arc shape, and the center of the rivet hole into which the rivet is inserted is formed on the one end side of the center of the arc that forms the one end, and offset to the opposite side from the hinge section. This effectively transmits the pressing force of the tab to improve can opening, and increases the opening area to improve pourability.

The can lid described in Patent Document 2 is known as a can lid with improved pouring properties compared to the can lid described in Patent Document 1. The can lid described in Patent Document 2 has a first score, a second score, and a third score that define an opening, and the first score defines a main opening overlapping one end of the tab together with the third score, and the second score defines a sub-opening formed in an area opposite the main opening with a rivet in between, and the first score and the second score are connected via the third score, and the first score is broken by raising the tab, and the third score is rotated around the rivet to twist the tab, which causes the third score to break and the second score to break. As a result, a large opening consisting of a main opening and a sub-opening is formed in the can lid, and the contents are efficiently discharged from the main opening by air that is allowed to flow freely into the can from the sub-opening.

JP 2012-35852 A Patent No. 4879759

However, the can lid described in Patent Document 1 does not improve pouring ease, although it does increase the opening area, whereas the can lid described in Patent Document 2 requires the tab to be rotated around the rivet and twisted in order to break the third score, making the can opening process cumbersome.

The present invention was made in consideration of these circumstances, and provides a can lid that has a simple structure and ensures good pouring properties.

The can lid of the present invention comprises a can lid body and a tab attached to the can lid body, and the can lid body is formed with an opening piece that is an opening defined by a first score and a second score, and a rivet that protrudes from the center of the upper surface of the can lid body and to which the tab is attached, and the opening piece has a first opening piece that is defined by the first score and protrudes from the periphery of the rivet to the peripheral edge of the upper surface of the can lid body, and a second opening piece that is defined by the second score and protrudes to the area opposite the first opening piece across the rivet, and the can In a plan view of the lid body, a line passing through the center of the rivet and parallel to the longitudinal direction of the tab is defined as a first reference line, and a line passing through the center of the rivet and perpendicular to the first reference line is defined as a second reference line. The first opening piece is formed so that its maximum width in the direction along the second reference line is greater than its length on the first reference line, the second score is formed in a substantially straight line, and its end is located in an area opposite the first score across the second reference line, and the shortest distance from the second reference line to the end of the second score is 0.5 to 1.5 times the maximum diameter of the rivet.

In the present invention, since the second score is formed in a substantially straight line, the breaking force of the first score is easily transmitted directly to the second score, and since the shortest distance from the second reference line to the end of the second score is formed to be short, at 0.5 to 1.5 times the maximum diameter of the rivet, the second score breaks smoothly in accordance with the breakage of the first score. In other words, the second score can be broken without rotating the tab, making the can opening operation easier. In addition, since there is no need to rotate the tab around the rivet to twist it, it is possible to prevent fingers from touching the score cross section, thereby improving the safety of the can lid. In addition, by extending the end of the second score that defines the second opening piece to the area opposite the first score across the second reference line, air can flow in stably from the second opening when the contents are poured out from the first opening, preventing the occurrence of pulsation, and allowing the contents to be poured out quickly and smoothly from the first opening to the outside. In addition, because the rivet holes are located closer to one end of the tab, the initial breaking force required to open the can is reduced, allowing the can to be opened with a relatively small force.

If the shortest distance from the second reference line to the end of the second score exceeds 1.5 times the maximum diameter of the rivet, the end of the second score may penetrate inside the tab. In this case, the panel is likely to expand when internal pressure is applied to the can, causing the tab to tilt left and right, which causes the tab pressing area to contact the first opening piece unevenly on the left and right, causing vibration leakage. In addition, since the second score is too long, it is not possible to break the entire area of the second score in line with the breakage of the first score, and it becomes necessary to rotate the tab, which is cumbersome. In addition, if the shortest distance from the second reference line to the end of the second score is less than 0.5 times the maximum diameter of the rivet, the second opening cannot be formed, and the contents cannot be quickly and smoothly poured out from the first opening to the outside.

In a preferred aspect of the can end of the present invention, a starting end of the first score, which is formed on the second score side of the first reference line, is formed in a convex arc shape that continues into a concave arc portion of an arc shape adjacent to the rivet and is positioned so as to straddle the second reference line, the arc center of the starting end is located on the first score side of the second reference line, and the distance between the arc center of the starting end and the second reference line is smaller than the radius of the rivet.
If the center of the arc of the starting end is located on the opposite side of the second reference line from the first score, the position of the starting end is too high, requiring a large force for the opening operation, which may make the can difficult to open. On the other hand, if the distance between the center of the arc of the starting end and the second reference line is greater than the radius of the rivet, the position of the starting end is too low, which may reduce the opening area of the opening and reduce pourability.

In a preferred embodiment of the can lid of the present invention, an angle between a tangent to the start end passing through the terminal end of the second score and the second reference line is 15° or more and 45° or less.
Here, when the second score is broken, the tangent line portion becomes a hinge portion, and the area surrounded by the second score, the tangent line, and the second reference line opens to become a second opening portion.
Furthermore, if the above angle is less than 15°, the second score will be too short, the position of the hinge portion will be low, and the area of the second opening will be small, making it difficult to improve pouring performance, and if the above angle is more than 45°, the second score will be too long, and it may not be possible to break the entire area of the second score in line with the breaking of the first score.

In a preferred embodiment of the can lid of the present invention, the opening area of the opening is 390 mm2 or ^more and 410 mm2 ^or less.
If the opening area of the opening is less than 390 ^mm2 , the opening area may be too small and the pouring property may be deteriorated, and even if the opening area exceeds 410 ^mm2 , the pouring property cannot be improved. It is more preferable that the opening area of the first opening is 380 ^mm2 or more and 385 ^mm2 or less, the opening area of the second opening is 5 ^mm2 or more and 30 ^mm2 or less, and the total of these is 390 ^mm2 or more and 410 ^mm2 or less.

In a preferred embodiment of the can lid of the present invention, the aspect ratio, which is the ratio of the length of a rectangle circumscribing the upper end and lower end of the opening piece in a direction along the first reference line and the left and right ends in a direction along the second reference line to the length of the rectangle in a direction along the first reference line, is 0.9 or more and 1.1 or less.
If the aspect ratio is less than 0.9, the second score will be too short, and the area of the second opening will be small, making it difficult to improve pourability. If the aspect ratio exceeds 1.1, the second score will be too long, and it may not be possible to break the entire area of the second score in line with the breaking of the first score.

In a preferred embodiment of the can lid of the present invention, a center line extending along the first reference line and passing through the center of the maximum width is shifted toward the second score side with respect to the first reference line.
In the case where the first opening piece is formed wide and the tab is located on the center line of the maximum width of the first opening piece, a large resistance occurs when the first opening piece is opened compared to a normal opening. In contrast, in the above embodiment, the center line of the maximum width of the first opening piece is shifted from the first reference line, so that the first score does not spread too far to the opposite side, thereby reducing the resistance when opening.

According to the present invention, it is possible to ensure good pouring, opening and safety with a relatively simple configuration of appropriately forming the second score shape.

FIG. 2 is a plan view showing the can lid of the present embodiment. 2 is a cross-sectional view of the can lid shown in FIG. 1 along the line AA. FIG. 2 is an enlarged view of the tab and score of the can lid shown in FIG. 1 . 13 is an enlarged view of a main portion illustrating the relationship between a rivet hole in a tab and a second score. FIG.

Hereinafter, one embodiment of a can lid of the present invention will be described with reference to the drawings.
The can lid 100 of this embodiment is a so-called stay-on-tab type can lid used for beverage cans, and as shown in FIG. 1, is composed of a can lid body 1 and a tab 2, and these can lid body 1 and tab 2 are each formed from an aluminum alloy.

As shown in Figures 1 and 2, the can lid body 1 is composed of a disk-shaped panel portion 10a located in the center, a countersink portion 13 that continues from the outer periphery of the panel portion 10a via a corner portion 11 and forms a downwardly facing annular recess 12, a chuck wall portion 14 that extends upward from the outer periphery of the countersink portion 13 while expanding in diameter, a shoulder portion 15 that continues from the outer periphery of the chuck wall portion 14, and a shoulder curl portion 16 that continues from the shoulder portion 15.

1, a rivet 3 is formed on the top surface of the panel portion 10a, protruding from the center of the panel portion 10a (can lid main body 1), and a tab 2 is attached to this rivet 3. In addition, an opening piece 5 defined by a score portion 4 is formed in a portion extending in a specific radial direction from the rivet 3 on the top surface of the panel portion 10a (below the rivet 3 in FIG. 1), and a finger hook recess 6 is formed on the opposite side of the rivet 3 from the opening piece 5 (above the rivet 3 in FIG. 1), and a pair of protrusions 7 called dimples are formed between the rivet 3 and the finger hook recess 6.
A concave panel debossing 10b is formed extending in the longitudinal direction of the tab 2 so as to surround the opening piece 5, the finger hook recess 6, and the protrusion 7, and the rigidity of the entire panel portion 10a is increased by the outer peripheral wall 10c that constitutes the panel debossing 10b.

1, the score portion 4 is composed of a first score 40A consisting of a starting end 41, a concave arc portion 42 that is an initial breaking portion of an arc shape that surrounds almost half of the rivet 3, and a substantially elliptical intermediate portion 43, and a second score 40B consisting of an extension portion 44 formed continuously from the first score 40A and an end portion 45 consisting of the end of the extension portion 44. The connection end 441 that connects the first score 40A and the second score 40B is formed at the same height as one end of the tab 2, for example, as shown in FIG. 3, and more specifically, coincides with the position of the base end of the extension portion 44 that extends in a substantially straight line. In addition, in this embodiment, in order to break the second score 40B in accordance with the breakage of the first score 40A, the remaining thickness of this connection end 441 is formed to be the same as the remaining thickness of the intermediate portion 43 and the extension portion 44 or thinner than the remaining thickness of the intermediate portion 43 and the extension portion 44.

3 and 4, the starting end 41 formed on the second score 40B side with respect to the first reference line S1 is formed in a convex arc shape continuing from the concave arc part 42 of the arc shape close to the rivet 3, and is arranged so as to straddle the second reference line S2. The arc center 41P of this starting end 41 (for example, the center of the convex arc located at the leftmost position of the starting end 41 among the multiple convex arcs constituting the starting end 41 in FIG. 4) is located on the first score 40A side with respect to the second reference line S2, and the distance L5 between the arc center 41P of the starting end 41 and the second reference line S2 is smaller than the radius L6 of the rivet 3. In other words, the arc center 41P of the starting end 41 is located below the center of the rivet 3 and above the contact point with the first reference line S1 on the outer periphery of the rivet 3, as shown in FIG. 3 and 4. More specifically, the arc center 41P is located about 1.1 mm below the center of the rivet 3.
If the arc center 41P of the starting end 41 is located on the second score 40B side of the second reference line S2, the position of the starting end 41 will be too high, requiring a large force for the opening operation, which may make the can difficult to open. On the other hand, if the distance L5 between the arc center 41P of the starting end 41 and the second reference line S2 is greater than the radius L6 of the rivet 3, the position of the starting end 41 will be too low, reducing the opening area of the opening and possibly reducing pourability.
Such a score portion 4 is formed between the starting end 41, the extending portion 44, and the ending end 45, leaving a part of a hinge portion 46 which is a connection portion with the panel portion 10a, and defines the opening piece 5. The concave arc portion 42 is formed in a ring-shaped coined portion which is crushed by coining around the rivet 3.

The score section 4 has a double structure with a main score 4a that breaks when pressed by the tab 2 to form an opening piece 5, and an auxiliary score 4b that is formed adjacent to and parallel to the inside of the main score 4a, and the main score 4a and the auxiliary score 4b are connected at the start end 41 and end end 45 of the score section 4. The auxiliary score 4b is formed shallower than the adjacent main score 4a, so that it will not break when pressed by the tab 2. As shown in Figure 4, the start end 41 is formed to be outwardly convex by a continuation of multiple arcs, and has an arc shape larger than the distance between the main score 4a and the auxiliary score 4b. The end end 45 has an arc shape with a diameter that is approximately the same as the distance between the main score 4a and the auxiliary score 4b.

The opening piece 5 has a first opening piece 5A defined by a first score 40A and protruding from the periphery of the rivet 3 to the peripheral edge of the upper surface of the can lid body 1, which constitutes a first opening, and a second opening piece 5B defined by a second score 5B and protruding to the area opposite the first opening piece 5A across the rivet 3. In a plan view of the can lid body 1, a line passing through the center of the rivet 3 and parallel to the longitudinal direction of the tab 2 is defined as a first reference line S1, and a line passing through the center of the rivet 3 and perpendicular to the first reference line S1 is defined as a second reference line S2. The first opening piece 5A is formed so that the maximum width W1 along the second reference line S2 is greater than the length on the first reference line S1, and the center line C along the first reference line S1 passing through the center of the maximum width W1 is shifted from the first reference line S1 toward the second score 40B in the direction along the second reference line S2 (to the left in Figures 1 and 3) (ΔW1 shown in Figure 3). The first opening piece 5A is set so that the maximum width W1 is set to be 18 mm or more and 26 mm or less, and the maximum length L1 is set to be smaller than the maximum width W1 in the range of 16 mm or more and 24 mm or less.

The second opening piece 5B is a portion that becomes the second opening by the breakage of the second score 40B, and is formed by partially opening the area of the hinge portion 46 on the second score 40B side as the second score 40B breaks. Specifically, the second opening is formed by opening the area surrounded by the second score 40B, the hinge portion 46, and the second reference line S2. The second score 40B for forming this second opening is formed in a substantially straight line as shown in Figures 1, 3, and 4, and its end (end portion 45) is located in an area on the opposite side of the second reference line S2 to the first score 40A. In addition, the shortest distance L4 from the second reference line S2 to the end (end portion 45) of the second score 40B is set to be 0.5 to 1.5 times the maximum diameter of the rivet 3. For example, when the diameter L3 of the rivet 3 is 4.2 mm, the shortest distance L4 is set to be 2.1 mm to 6.3 mm. It is more preferable that this shortest distance L4 be between 0.5 and 1.0 times the maximum diameter of the rivet 3.

If the shortest distance L4 from the second reference line S2 to the end of the second score 40B (end portion 45) exceeds 1.5 times the maximum diameter of the rivet 3, the end of the second score 40B may penetrate into the inside of the tab 2. In this case, the panel is likely to expand when internal pressure is applied to the can, and the tab 2 tilts left and right. This causes the tab pressing portion to hit the first opening piece 5A unevenly left and right, causing vibration leakage. In addition, since the second score 40B (extension portion 44) is too long, the entire area of the second score 40B cannot be broken in accordance with the breaking of the first score 40A, and it becomes necessary to rotate the tab 2, which is troublesome. In addition, if the shortest distance L4 from the second reference line S2 to the end of the second score 40B is less than 0.5 times the maximum diameter of the rivet, the second opening cannot be formed, and the contents cannot be quickly and smoothly poured out from the first opening to the outside.

The opening areas of the openings (first opening and second opening) formed by breaking the first score 40A and the second score 40B are set to 390 mm2 or ^more and 410 ^mm2 or less. Specifically, it is preferable that the opening area of the first opening is 380 mm2 or ^more and 385 ^mm2 or less, the opening area of the second opening is 5 mm2 or ^more and 30 ^mm2 or less, and the total of these is 390 ^mm2 or more and 410 ^mm2 or less.
If the opening area of this opening is less than 390 ^mm2 , the opening area may be too small and the pouring performance may decrease, and even if the opening area exceeds 410 ^mm2 , the pouring performance cannot be improved. For example, if only the area of the first opening is enlarged and the area of the second opening remains small (less than 5 ^mm2 ), it may be difficult to suppress the occurrence of pulsation, and if only the area of the second opening is enlarged (more than 30 ^mm2 ), the length of the second score 40B will inevitably increase, making it difficult to break the entire area of the second score 40B in conjunction with the breakage of the first score 40A.
It is more preferable that the opening area of the second opening is 5 mm2 or ^more and 20 ^mm2 or less.

Moreover, it is preferable that the aspect ratio of a rectangle K1 circumscribing the upper end and the lower end in the direction along the first reference line S1 and the left and right end in the direction along the second reference line S2 of such an opening piece 5 is 0.9 to 1.1, the aspect ratio being the ratio of the length in the direction along the first reference line S1 (hereinafter, the vertical length) to the length in the direction along the second reference line S2 (hereinafter, the horizontal length). In other words, it is preferable that the relationship between the horizontal length and the vertical length of the rectangle K1 is as shown in the following formula (1).
Horizontal length of rectangle K1: Vertical length of rectangle K1 = 1: 0.9 or more and 1.1 or less (1)
If the aspect ratio is less than 0.9, the second score 40B is too short, and the area of the second opening is small, making it difficult to improve pourability, and if the aspect ratio exceeds 1.1, the second score 40B is too long, and there is a possibility that the entire area of the second score 40B cannot be broken in time with the breaking of the first score 40A. It is more preferable that the aspect ratio is 0.9 or more and 1.0 or less.

As shown in Fig. 4, the start end 41 of the first score 40A is disposed so as to straddle the second reference line S2. The angle θ1 between the tangent of the start end 41 passing through the end of the second score 40A at the start end 41 and the second reference line S1 is set to be 15° or more and 45° or less, more preferably 15° or more and 40° or less. As described above, when the second score 40B is broken, the tangent portion becomes the hinge portion 46, and the area surrounded by the second score 40B, the tangent line, and the second reference line S2 opens to become the second opening. The length of the straight line extending from the center of the rivet 3 to the end of the second score 40B is set to be 7 mm or more and 9 mm or less.
For example, as in the case of score 43A in the can lid described in Patent Document 1, shown by the dotted line in Figure 4, if the angle θ1 is less than 15° (-13° in the example of the dotted line in Figure 4), the second score 40B will be too short, and the area of the second opening will be small (the second opening cannot be formed), making it difficult to improve pouring ease, and if the angle θ1 exceeds 45°, the second score 40B will be too long, and it may not be possible to break the entire area of the second score 40B in conjunction with the breaking of the first score 40A.
Further, an inner bead 8 is formed on the opening piece 5 so as to protrude along the score portion 4, thereby reinforcing the opening piece 5.

The tab 2 is cut out from a metal plate such as aluminum and formed flat by pressing or the like, and has one end 21 arranged overlapping above the opening piece 5, and a pull-up portion 22 at the other end formed on the opposite side across the rivet 3, and a tab hole portion 23 that opens in the thickness direction of the tab 2 is formed in the pull-up portion 22.
One end 21 is formed in an arc shape, and a tongue portion 24 is formed between this one end 21 and the lifting portion 22 by a U-shaped slot 24a, and a rivet hole 25 is formed in the tongue portion 24. The rivet 3 is inserted into the rivet hole 25, and the tab 2 is attached with the lower surface of the tongue portion 24 abutting against the surface of the panel deboss 10b.

The tab 2 has a total length L2 of 22 mm to 26 mm and a total width W2 of 12 mm to 16 mm. The center 20c of the arc forming the one end 21 of the tab 2 is formed on the opposite side to the one end 21 (upper side in FIG. 3) from the center 25c of the rivet hole 25 of the tab 2 (center of the rivet 3), as shown in FIG. 3, and is shifted toward the second score 40B side (left side in FIG. 3) with respect to the first reference line S1. In this case, when the point of the rivet hole 25 closest to the one end 21 is set as a reference (reference point d), the ratio (L22/L21) of the length L22 from the reference point d to the one end 21 to the length L21 from the other end of the tab 2 to the reference point d is set to 0.25 to 0.30. The shift amount ΔW2 of the center 25c of the rivet hole 25 is set to 0.2 mm to 0.5 mm.
The rivet 3 is formed by coining the periphery of the center of the panel portion 10a from above into a ring shape, causing the center of the panel portion 10a to bulge upward.

The finger hook recess 6 is provided to facilitate lifting by positioning a fingertip below the lifting portion 22 of the tab 2, and is formed radially outward in the panel portion 10a near the lower portion of the lifting portion 22.
Further, a side surface 61 of the finger hook recess 6 is provided continuous with a part of the outer peripheral wall 10c of the panel deboss 10b, and a bottom surface 62 thereof is formed by being recessed further downward from the upper surface of the panel deboss 10b.

The protrusions 7 protrude from the upper surface of the panel debossing 10b, and are formed in pairs spaced apart from one another in the width direction of the tab 2. The outer edge of the tab 2 is caught by the pair of protrusions 7, preventing the tab 2 from rotating.

In the can lid 100 thus constructed, when the lifting portion 22 of the tab 2 is pulled upward, the rivet 3 is first lifted upward with one end 21 of the tab 2 on the opening piece 5 as a fulcrum. As a result, with the opening piece 5 side of the concave arc portion 42 of the main score 4a being pressed by the tab 2, the rivet 3 side of the concave arc portion 42 is lifted upward, and a shear force acts on the concave arc portion 42, causing it to break (this is referred to as the popping operation).
Then, as the tab 2 is further lifted, the rivet 3 becomes the fulcrum and the point of action becomes one end 21 of the tab 2, and the first opening piece 5A surrounded by the main scores 4a is pushed into the can by the tab 2, causing the main scores 4a to break one after another, opening around the first opening piece 5A, and then the second opening piece 5B opens (the period after the popping operation is called the tearing operation).In other words, in this embodiment, simply by lifting the tab 2, the first score 40A and the second score 40B are broken in this order, thereby forming the first opening and the second opening.
At this time, as the pulling-up portion 22 of the tab 2 is pulled upward, the position at which one end 21 of the tab 2 contacts the first opening piece 5A moves so as to rotate little by little clockwise around the rivet 3 along the arc shape of the one end 21.

In the can lid 100 of this embodiment, the second score 40B is formed in a substantially straight line, so that the breaking force of the first score 40A is easily transmitted directly to the second score 40B, and the shortest distance from the second reference line S2 to the end of the second score 40B is formed to be short, at 0.5 to 1.5 times the maximum diameter of the rivet 3, so that the second score 40B breaks smoothly in accordance with the breakage of the first score 40A. In other words, the second score 40B can be broken without rotating the tab 2, making the can opening operation easier. In addition, since there is no need to rotate and twist the tab 2 around the rivet, it is possible to prevent fingers from touching the cross section of the score 40, thereby improving the safety of the can lid 100. In addition, by extending the end of the second score 40B that defines the second opening piece 5B to the area opposite the first score 40A across the second reference line S2, air can flow steadily through the second opening when pouring the contents from the first opening, preventing pulsation and allowing the contents to be poured out quickly and smoothly from the first opening. In addition, since the rivet hole 25 is located closer to the one end 21 of the tab 2, the initial breaking force at the time of opening can be reduced, and the can can be opened with a relatively small force.

Furthermore, when the first opening piece 5A is formed wide and the tab 2 is located on the center line C of the maximum width W1, a large resistance occurs when the first opening piece 5A is opened compared to a normal opening. In contrast, in this embodiment, the center line C of the maximum width W1 of the first opening piece 5A is shifted from the first reference line S1 to prevent the first score 40A from spreading too far to the opposite side. The center 20c of the arc forming one end 21 of the tab 2 is formed on the opposite side of the one end 21 from the center 25c of the rivet hole 25, and is shifted toward the second score 40B with respect to the first reference line S1. In other words, the center 25c of the arc is shifted toward the center line C of the maximum width W1 of the first opening piece 5A in accordance with the shift of the center line C of the maximum width W1 of the first opening piece 5A. This allows the first score 40A to start breaking at a position close to the center line C of the maximum width W1 of the first opening piece 5A, reducing the resistance generated when the first opening piece 5A is opened. In addition, the rivet hole 25 is formed closer to the first opening piece 5A than the center 25c of the arc forming one end 21 of the tab 2, so that the pressing force of the tab 2 can be effectively transmitted to the first opening piece 5A, improving the can opening property.

The present invention is not limited to the configuration of the above embodiment, and various changes can be made to the details of the configuration without departing from the spirit of the present invention.
For example, in the above embodiment, the tab 2 is formed so that the center 20c of the arc forming one end 21 of the tab 2 is on the opposite side of the one end 21 from the center 25c of the rivet hole 25, and is shifted toward the second score 40B with respect to the first reference line S1, but this is not limited to the above and the position does not have to be shifted.

[0023] 100 Can lid 1 Can lid body 2 Tab 3 Rivet 4 Score portion 4a Main score 4b Auxiliary score 5 Opening piece 5A First opening piece 5B Second opening piece 6 Finger hook recess 7 Convex portion 8 Inner bead 10a Panel portion 10b Panel debossing 10c Outer circumferential wall 11 Corner portion 12 Annular recess 13 Countersink portion 14 Chuck wall portion 15 Shoulder portion 16 Shoulder curl portion 21 One end portion 22 Pull-up portion 23 Tab hole portion 24 Tongue portion 25 Rivet hole 40A First score 40B Second score 41 Starting end portion 41P Circular arc center 42 Concave arc portion 43 Middle portion 44 Extension portion 45 End portion 46 Hinge portion 61 Side surface 62 Bottom surface C Center line

Claims (4)

A can lid body includes a can lid body and a tab attached to the can lid body, the can lid body being formed with an opening piece that becomes an opening defined by first scores and second scores, and a rivet that protrudes from a center of an upper surface of the can lid body and to which the tab is attached, the opening piece having a first opening defined by the first scores and protruding from a peripheral portion of the rivet to a peripheral edge portion of the upper surface of the can lid body, and a second opening piece that is defined by the second scores and becomes a second opening that protrudes to a region opposite the first opening piece across the rivet, and in a plan view of the can lid body, a line that passes through the center of the rivet and is parallel to the longitudinal direction of the tab is defined as a first reference line, and a line that passes through the center of the rivet and is perpendicular to the first reference line is defined as a second reference line.
the first opening piece is formed so that its maximum width in a direction along the second reference line is larger than its length on the first reference line, and a start end of the first score formed on the second score side with respect to the first reference line is formed in a convex arc shape continuing to a concave arc portion of an arc shape adjacent to the rivet and is disposed so as to straddle the second reference line, and the arc center of the start end is located on the first score side with respect to the second reference line,
the second score is formed in a substantially straight line, and its end is located in an area opposite the first score across the second reference line, the shortest distance from the second reference line to the end of the second score is 0.5 to 1.5 times the maximum diameter of the rivet, and the angle between a tangent to the start end passing through the end of the second score and the second reference line is 15° to 45°,
A can lid, characterized in that a center line along the first reference line passing through the center of the maximum width is shifted toward the second score side with respect to the first reference line. 2. The can lid according to claim 1, wherein a distance between the center of the arc of the starting end and the second reference line is smaller than a radius of the rivet. 3. The can lid according to claim 1, wherein the opening has an opening area of 390 ^mm2 or more and 410 ^mm2 or less. A can lid according to any one of claims 1 to 3, characterized in that the aspect ratio, which is the ratio of the length along the first reference line to the length along the second reference line of a rectangle circumscribing the upper end, the lower end, and the left and right ends along the second reference line of the opening piece, is 0.9 to 1.1.

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