Can cap and can

Abstract

To provide a can cap, which is suitable for opening by pushing in a tool to break the score, is excellent in pressure resistance and can-opening, and is also excellent in stacking, without major change in conventional manufacturing equipment, etc.SOLUTION: There is a disk-shaped panel part, the panel part has a planned opening part and a panel outer periphery part, the planned opening part has a hinge part, a score and protrusion formed with the hinge part left, the boundary between the planned opening part and the panel outer periphery part consists of the hinge part and the score, the score has a pair of arc-shaped portions formed on both sides of the planned opening part so as to be convex radially outward of the planned opening part, and an inwardly convex arc part that connects both ends of the arc-shaped portions on the opposite side to the hinge part and is convex toward the radially inward direction of the planned opening part, and the protrusion is formed in close proximity to the inwardly convex arc part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a can lid that opens by pushing in a planned opening portion surrounded by a score, and a can using this can lid.

Background Art

[0002] As a can lid that opens by pushing in a planned opening portion surrounded by a score with a human finger, for example, those described in Patent Document 1 and Patent Document 2 are known. The can lid described in Patent Document 1 has two planned opening portions formed by two circular scores in a disk-shaped panel portion. By opening one of the planned opening portions, an air vent hole is formed, and then the other relatively large planned opening portion is opened and used as a drinking mouth for the beverage. In both cases, the inside of the portion surrounded by the score is convexly deformed so that the score can be broken by pushing in the convex portion with a finger. The can lid described in Patent Document 2 has a score formed along the outer peripheral edge of the panel portion and is configured to be able to open the entire panel portion. In this case, the panel portion itself is formed in a large convex shape and protrudes above the flange portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, there has been a demand for beverage servers such as small beer servers, and it has been considered to use a can of the size of a normal beverage can instead of a keg can of several liters in size for the server. In that case, it is conceivable to adopt a can in which the score is broken by pushing the planned opening part into the can to open the planned opening part.

[0005] However, if two planned opening parts are opened as in Patent Document 1, two opening operations are required, resulting in poor work efficiency. On the other hand, if the panel part protrudes greatly upward from the peripheral part like the can lid of Patent Document 2, it is difficult to convey the can lid.

[0006] The present invention has been made in view of such circumstances, and is suitable for breaking the score by pushing in an instrument to open it, has excellent pressure resistance and can-opening properties, and can be manufactured without significant changes to conventional manufacturing equipment, etc., and aims to provide a can lid with excellent transportability.

Means for Solving the Problems

[0007] The can lid of the present invention includes a disc-shaped panel part, the panel part includes a planned opening part and a panel outer peripheral part, the planned opening part includes a hinge part, a score formed leaving the hinge part, and a protrusion part, and the boundary between the planned opening part and the panel outer peripheral part consists of the hinge part and the score. An inward convex arc part that protrudes toward the center direction of the planned opening part is formed in a part of the score. The protrusion part is formed close to the outer side in the radial direction of the inward convex arc part.

[0008] By pushing the protrusion part downward, the score is broken and the planned opening part is pushed in to open. Since the score forms an inward convex arc part in the vicinity of the protrusion part, the inward convex arc part can be broken first by pushing the protrusion part, facilitating the first break of the score that requires the most force in the opening operation and enabling the subsequent overall break to be performed smoothly.

[0009] In addition, since an inwardly convex arc portion is formed in a part of the score, a slight resistance is generated between the break (pop) of the first inwardly convex arc portion and the break (tear) of the other part of the score, preventing the score from breaking all at once from the beginning to the end.

[0010] In addition, since the panel portion is formed in a disc shape and has a score and a protrusion on the panel portion, it is possible to manufacture by applying the forming techniques of the panel portion, score, and rivet of the conventional tabbed can lid, and it can be manufactured without significant changes to the equipment. Furthermore, the protrusion can be formed to be about the size of a conventional rivet without protruding significantly above the can lid as in Patent Document 2, so it has excellent stackability and does not impair the transportability.

[0011] In the can lid of the present invention, the inwardly convex arc portion may be arranged on the side opposite to the hinge portion via the center of the planned opening portion.

[0012] In the can lid of the present invention, the score has a pair of arc-shaped portions formed to be convex outward in the radial direction of the planned opening portion on both sides of the planned opening portion, and the inwardly convex arc portion may be formed to connect both ends of both arc-shaped portions.

[0013] Since it breaks from the break (pop) of the first inwardly convex arc portion to the hinge portion, the tearing operation can also be performed smoothly, and the pushing-in amount can be reduced. In addition, since the inwardly convex arc portion that is convex toward the inside of the planned opening portion and the arc-shaped portion that is convex toward the outside of the planned opening portion are connected, resistance can be generated when the break of the score moves from the inwardly convex arc portion to the arc-shaped portion.

[0014] In this case, it is preferable that a concave portion or a convex portion extending along the arc-shaped portion to a position in the middle of the arc-shaped portion inside the arc-shaped portion and the hinge portion is formed in the planned opening portion. The concave portion or the convex portion may have a bead shape, may be one concave portion or one convex portion, or may be a plurality of concave and convex portions.

[0015] The planned opening portion is reinforced by the concave portion or the convex portion, and the bulging deformation due to the internal pressure is suppressed. Therefore, the pop value is reduced, the dropping performance is improved, and it becomes easier to break the score. Further, since the tip of the concave portion or the convex portion is in the middle of the arc-shaped portion, the rigidity of the planned opening portion changes at that portion, so that it is possible to prevent the score from breaking all at once from the beginning to the end.

[0016] In the can lid of the present invention, it is preferable that the planned opening portion is formed at the central portion in the radial direction.

[0017] When applied to a beverage server, a cylindrical opening device for opening is inserted from the opening portion. In that case, it is possible to open by pushing the planned opening portion by the cylindrical opening device. When the planned opening portion is formed at the central portion in the radial direction, it becomes easy to position the cylindrical opening device and the planned opening portion.

[0018] In the can lid of the present invention, the protruding end portion of the protruding portion may be formed in a spherical shell shape. The spherical shell-shaped protruding portion can be formed by the forming technique of the rivet of a general tabbed can lid, and the production is easy. It also has sufficient strength against dropping impact and the like.

[0019] Alternatively, the protruding portion may be formed on a tapered surface whose protruding end portion is inclined with respect to the panel portion, and the tapered surface may be inclined so that the height from the surface of the panel portion gradually increases from the hinge portion toward the inward convex arc portion. Since the position close to the inward convex arc portion is the highest position of the tapered surface, by pushing the protruding portion, the pushing-down force can be concentrated near the inward convex arc portion, and the initial opening becomes easy.

[0020] In the can lid of the present invention, it is preferable that a panel deposit portion is formed in an annular shape so as to surround the outside of the planned opening portion.

[0021] The panel deposit portion reinforces the panel portion around the planned opening portion, and the rigidity can be increased.

[0022] The can of the present invention is formed by winding and tightening the can lid according to any one of the above on a can body filled with contents.

Advantages of the Invention

[0023] According to the can lid of the present invention, it can be used for beverage servers such as beer servers, has excellent pressure resistance and openability, can be manufactured without significant changes to conventional manufacturing equipment, etc., and also has excellent transportability.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Mode for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described. As shown in FIG. 1, the can lid 10 of one embodiment is wound and tightened around the opening end of a bottomed cylindrical can body 20 made of, for example, aluminum or an aluminum alloy. As shown in FIG. 1, this can body 20 is made of a thin sheet metal of aluminum or an aluminum alloy, and has a cylindrical body portion 21 and a bottom portion 22 provided at one end of the body portion 21. Further, a shoulder portion 23 that gradually decreases in diameter upward is formed in the body portion 21, a small-diameter neck portion 24 is formed at the upper end of the shoulder portion 23, and a flange portion 25 that extends radially outward is formed at the upper end of the neck portion 24. Although the dimensions are not limited, the outer diameter of the body portion 21 is the so-called 211 diameter, and the internal volume is 350 ml.

[0026] As shown in FIGS. 2 and 3, the can lid 10 includes a disk-shaped panel portion 11 disposed at the central portion thereof, a countersink portion 13 that forms an annular recess 12 that is continuous from the outer peripheral edge of the panel portion 11 and extends downward, a chuck wall portion 14 that extends upward while substantially expanding in diameter from the outer peripheral edge of the countersink portion 13, a shoulder portion 15 that is continuous from the outer peripheral edge of the chuck wall portion 14, and a curl portion 16 that is continuous from the shoulder portion 15.

[0027] The panel portion 11 is formed with a score 33 that demarcates a planned opening portion 31 at its central portion and leaves a hinge portion 32 that connects the planned opening portion 31 to the outer peripheral portion of the panel portion 11, and a protruding portion 34 that protrudes upward from a part of the planned opening portion 31.

[0028] The score 33 is formed in a shape that opens a part of a circle leaving the hinge portion 32, and has a pair of arc-shaped portions 35 formed on both side edges of the planned opening portion 31 so as to protrude outward in the radial direction of the planned opening portion 31, and an inwardly convex arc portion 36 that connects both end portions of both arc-shaped portions 35 on the side opposite to the hinge portion 32 and protrudes inward in the radial direction of the planned opening portion 31.

[0029] Both arc-shaped portions 35 are formed in an arc shape that protrudes outward in the radial direction from each other, and are arranged on the 180° opposite side via the center C1 of the panel portion 11 (which is also the center of the can lid 10). And one end portion between both arc-shaped portions 35 is opened as the hinge portion 32, and the inwardly convex arc portion 36 is formed between the other end portions. This inwardly convex arc portion 36 is formed in an arc shape that protrudes in the direction of the center of the planned opening portion 31 (which is also the center of the panel portion 11 in the illustrated example) in the direction opposite to the direction of the arc of the arc-shaped portion 35. The arc-shaped portion 35 and the inwardly convex arc portion 36 are connected by a connecting arc portion 37 having a slight size that protrudes outward in the radial direction.

[0030] The hinge portion 32 and the inwardly convex arc portion 36 are arranged so as to face in a direction orthogonal to the facing direction of both arc-shaped portions 35, and the center position in the width direction of the hinge portion 32 (the facing direction of both arc-shaped portions 35), the center position of the inwardly convex arc portion 36 (the center position along the facing direction of both arc-shaped portions 35), and the center C1 of the panel portion 11 are arranged on a straight line along the radial direction of the panel portion 11. And the score 33 is formed symmetrically with respect to the diameter line X passing through these centers. Therefore, as shown in FIG. 4, the center of curvature C2 of the inwardly convex arc portion 36 is arranged on the diameter line X that becomes the axis of this line symmetry, and the apex 36a of the inwardly convex arc portion 36 is also arranged on the diameter line X.

[0031] Further, the center of curvature of the arc-shaped portion 35 is disposed at the center C1 of the panel portion 11. Therefore, the planned opening portion 31 is disposed at the center portion of the panel portion 11. And the score 33 and the hinge portion 32 that partition this planned opening portion 31 form the boundary between the inner peripheral portion (panel inner peripheral portion) and the outer peripheral portion (panel outer peripheral portion) of the panel portion 11.

[0032] In this case, the outer diameter D1 of the can lid 10 (the outer diameter of the curled portion 16) is 58.0 mm or more and 65.0 mm or less, more preferably 61.9 mm or more and 62.5 mm or less. The radius R1 of the arc-shaped portion 35 is 2.5 mm or more and 23.5 mm or less, more preferably 9.0 mm or more and 11.0 mm or less. The radius R2 of the inwardly convex arc portion 36 is smaller than the radius R1 of the arc-shaped portion 35, 0.65 mm or more and 4.0 mm or less, more preferably 2.7 mm or more and 2.9 mm or less. The radius of the connecting arc portion 37 is formed to be 0.65 mm or more and 4.0 mm or less, more preferably 1.2 mm or more and 1.4 mm or less. Also, the area of the planned opening portion 31 surrounded by the score 33 and the hinge portion 32 is 15.8 mm 2 or more and 1734 mm 2 or less, preferably 254.3 mm 2 or more and 379.9 mm 2 or less. For example, when the outer diameter of the can lid 10 is 62.2 mm, the radius of the arc-shaped portion 35 is 10.3 mm, the radius of the inwardly convex arc portion 36 is 2.8 mm, the radius of the connecting arc portion 37 is 1.3 mm, and the area of the planned opening portion 31 is 334.5 mm 2 is set.

[0033] Also, as shown in FIG. 4, the end of the arc-shaped portion 35 on the side opposite to the inward convex arc portion 36 is bent by a small arc portion 38 in the direction opposite to the arc-shaped portion 35 in order to prevent the hinge portion 32 from breaking when the score is broken. The space between the small arc portions 38 is formed as a hinge portion 32 that connects the planned opening portion 31 to the outside. The width W1 of the hinge portion 32 is formed to be 5.0 mm or more and 11.0 mm or less, preferably 9.8 mm or more and 10.2 mm or less. The distance W2 between the ends of the small arc portion 38 is larger than the width W1 of the hinge portion 32, preferably W1+(0.2 to 1.0) mm, and is formed to be, for example, 10.6 mm.

[0034] The score 33 breaks by pushing down the planned opening portion 31 during opening. A relatively shallow auxiliary score 51 is formed inside this score 33. By providing this auxiliary score 51, the auxiliary score stops the flow of the material during the formation of the score 33, enabling the score 33 to be finished accurately and preventing the occurrence of cracks. This auxiliary score 51 is separated on both sides of the protrusion 34 (or the inward convex arc portion 36) and is formed along both the arc-shaped portions 35 and the small arc portion 38, respectively. The outer score 33 that breaks during opening is called the main score, while the inner score 51 that does not break may be referred to as an auxiliary score or a sub-score. Unless otherwise particularly distinguished in this specification, the score 33 refers to the main score that breaks during opening.

[0035] Further, both arc-shaped portions 35 are formed such that their cross-sectional shapes and depths are different in the vicinity of an angle θ = 20° on one side from the aforementioned diameter line X. With respect to the panel portion 11 having a plate thickness of 0.200 mm or more and 0.310 mm or less (preferably 0.225 mm or more and 0.24 mm or less), up to the vicinity of the angle θ = 20°, as shown in FIG. 5, the thickness (score remaining thickness) E1 left by the score 33 is 0.090 mm or more and 0.130 mm or less, and the width H1 of the score bottom is 0.020 mm or more and 0.040 mm or less. From θ = 20°, the score remaining thickness E1 is 0.090 mm or more and 0.170 mm or less, and the width H1 of the score bottom is 0.020 mm or more and 0.077 mm or less. At the transition portion of this score 33, the bottom of the score is formed as an inclined surface of 45° up to the position of θ = 20°. For example, up to the vicinity of θ = 20°, the score remaining thickness E1 is 0.105 mm and the width H1 of the score bottom is 0.033 mm. At the position of 20°, the score remaining thickness E1 is 0.135 mm and the width H1 of the score bottom is 0.061 mm.

[0036] Also, in the planned opening portion 31, inside the score 33 (further inside the auxiliary score 51), a recess 52 formed of a bead-shaped recess in the illustrated example is formed along the score 33. This recess 52 is formed by deforming a part of the planned opening portion 31 downward, and is formed along the arc-shaped portion 35 inside the arc-shaped portion 35 and the hinge portion 32, and extends to both side positions of the protrusion portion 34. This recess 52 is formed in an arc shape (C-shaped in the drawing) centered on the center C1 of the panel portion 11, and is arranged concentrically with the arc-shaped portion 35 of the score 33.

[0037] The protrusion 34 has its center C3 disposed on the diameter line X which is the axis of line symmetry described above, near the apex 36a of the inwardly convex arc portion 36 and radially outward of the inwardly convex arc portion 36. This protrusion 34 has a shape in which a rivet for a beverage can lid with a tab is formed halfway. That is, as shown in FIG. 6(d), this protrusion 34 is formed by a rising bending portion 41 rising from the panel portion 11, a cylindrical portion 42 extending upward from the inner peripheral edge of the rising bending portion 41, and a spherical shell-shaped protruding end portion 43 formed at the upper end of the cylindrical portion 42. Further, around the rising bending portion 41, thin-walled portions 44, 45 thinner than the overall plate thickness of the panel portion 11 are formed in an annular shape. These thin-walled portions 44, 45 are formed with two levels of thickness such that the inner thin-walled portion 45 is thinner than the outer thin-walled portion 44. The inwardly convex arc portion 36 is formed in these thin-walled portions 44, 45.

[0038] To form this protrusion 34, as shown in FIG. 6(a), the panel portion 71 forms a flat can lid shell 70. First, as shown in FIG. 6(b), at the position where the protrusion 34 is to be formed, a down-bubble portion 73 is formed so as to protrude in the direction opposite to the forming direction of the protrusion 34. Next, as shown in FIG. 6(c), while forming a protrusion 74 in the direction opposite to the down-bubble portion 73 with a diameter smaller than the diameter of the down-bubble portion 73, the material around the protrusion 74 is compressed (coined) in the thickness direction to concentrate a large amount of the material on the protrusion 74 (by this, the outer thin-walled portion 44 is formed). Then, as shown in FIG. 6(d), while further performing peripheral coining, the inner thin-walled portion 45 is formed and the protrusion 74 is processed to a smaller diameter, thereby forming the protrusion 34.

[0039] This protrusion 34 is formed such that the diameter of the cylindrical portion 42 is 3.0 mm or more and 5.0 mm or less (preferably 3.5 mm or more and 3.9 mm or less), and the height is 1.7 mm or more and 2.2 mm or less. Further, the distance L1 from the center C1 of the panel portion 11 is formed to be equal to the radius of the cylindrical opening device 66 of the beverage server described later, and when the cylindrical opening device 66 is arranged at the can lid center C1 as shown by the two-dot chain line in FIG. 4, the protrusion 34 is formed in a positional relationship where it is arranged directly below the wall of the cylindrical opening device 66. Further, the distance L2 between the center C3 of the protrusion 34 and the apex 36a of the inward convex arc portion 36 is formed to be 1.8 mm or more and 3.0 mm or less, preferably 2.0 mm or more and 2.5 mm or less, and the outer peripheral edge of the rising arc 41 portion is arranged so as to substantially overlap the apex 36a of the inward convex arc portion 36.

[0040] Further, the panel portion 11 is formed to be substantially flat except for the score 33, the concave portion 52, and the protrusion 34, but an annular panel deposit portion 53 is formed outside the score 33. This panel deposit portion 53 has a shape in which the first inclined surface portion 53a on the inner peripheral portion and the second inclined surface portion 53b on the outer peripheral portion are continuous, and the second inclined surface portion 53b is formed to have a smaller inclination angle with respect to the horizontal plane and wider than the first inclined surface portion 53a.

[0041] The can lid 10 configured as described above is wound and tightened around the flange portion 25 of the can body 20 filled with beverage, and is provided as a beverage can (the can of the present invention) 60 applicable to a beverage server such as a beer server. As shown in FIG. 7, the beverage server is provided with a cylindrical opening device 66 that presses the planned opening portion 31 of the can lid 10 of the beverage can 60 to break the score 33 and push the planned opening portion 31 into the beverage can 60, and can move up and down by a drive portion (not shown). The cylindrical opening device 66 has, for example, an outer diameter of 16 mm and an inner diameter of 12 mm.

[0042] When the beverage can 60 is placed directly below the cylindrical opening device 66, as shown by the two-dot chain line for the cylindrical opening device 66 in Fig. 4, the protrusion 34 of the can lid 10 is disposed directly below the wall of the cylindrical opening device 66. In this state, by lowering the cylindrical opening device 66, the cylindrical opening device 66 presses the protrusion 34. Due to the pressing of this protrusion 34, among the scores 33, the apex 36a of the inner convex arc portion 36 closest to the protrusion 34 is pushed down and broken (pop), and then the arc-shaped portion 35 is sequentially broken via the connecting arc portion 37 from the inner convex arc portion 36 (tear).

[0043] At this time, since the curvature of the arc changes from the inner convex arc portion 36 to the connecting arc portion 37, some resistance is generated in the breaking of the score 33 between the pop and the tear. Therefore, it is possible to prevent the score 33 from breaking all at once (without distinguishing between the pop and the tear). Regarding this point, since the remaining thickness E1 and the bottom width H1 of the score 33 change to be thick and wide in the vicinity of the angle θ = 20°, the occurrence of the phenomenon that the score 33 breaks all at once due to the resistance generated when the score 33 breaks beyond the vicinity of θ = 20° is surely prevented. In this way, since resistance is generated in the breaking of the score 33 in several stages from the pop, it is possible to surely suppress the score 33 from breaking all at once.

[0044] Also, in the arc-shaped portion 35, a concave portion 52 is formed on the inner side and the planned opening portion 31 is reinforced, so the arc-shaped portion 35 is likely to break. Further, since the tip of this concave portion 52 is in the middle of the arc-shaped portion 35, the rigidity of the planned opening portion 31 changes at that part, and the occurrence of the phenomenon that the score 33 breaks all at once can be more surely prevented.

[0045] Note that since the lid 10 of this can has a panel portion 11 formed in a disc shape and having a score 33 and a protrusion 34, it can be manufactured by applying the forming techniques for the panel portion, score, and rivet of a conventional tabbed can lid, and can be manufactured without significant changes to the equipment. Also, tabbed can lids having these panel portions, scores, and rivets have a track record in terms of pressure resistance and drop impact resistance, and the lid 10 of the present invention can similarly have sufficient pressure resistance and drop impact resistance.

[0046] In this regard, the area of the planned opening portion 31 partitioned by the score 33 and the hinge portion 32 is 1734 mm 2 formed below, and if this area exceeds 1734 mm 2 there is a risk of blow-up during deformation due to internal pressure or drop impact. Note that the hinge portion 32 is also necessary to keep the planned opening portion 31 connected to the panel portion 11 without falling into the can when the score 33 is broken by the cylindrical opening tool 66. However, if the width W1 of this hinge portion 32 is too wide, there is a risk that the planned opening portion 31 will catch on the cylindrical opening tool 66 and prevent it from rising when the cylindrical opening tool 66 is raised after breaking the score 33 with the cylindrical opening tool 66. For this reason, with respect to the area of the planned opening portion 31 being 15.8 mm 2 or more and 1734 mm 2 or less, the width W1 of the hinge portion 32 is set to be 5.0 mm or more and 11.0 mm or less.

[0047] Also, since the protrusion 34 also has a protrusion amount similar to that of a conventional rivet, as shown in FIG. 8, when multiple lids 10 are stacked, each lid 10 is stacked almost parallel to each other, so the stacked state is stable and it is possible to prevent them from being stacked in an inclined state and collapsing. Also, since there are no protrusions such as the protrusion 34 above the lid 10 like the lid of Patent Document 2, there is no catching during conveyance, and the conveyance performance is also good. Also, the lid cutting performance during can lid winding is good.

[0048] Although an example in which the can lid of the present invention is applied to a beverage can filled with a beverage has been shown, it can be similarly applied to cans filled with contents other than beverages.

[0049] Figures 9 and 10 show other embodiments of the protrusion. Since the configurations other than the protrusion are the same, detailed descriptions thereof are omitted. The protrusion 81 of this can lid 80 is formed on a tapered surface 82 whose upper surface of the protruding end portion is inclined with respect to the surface (horizontal plane) of the panel portion 11. This tapered surface 82 is inclined so that the height from the surface of the panel portion 11 gradually increases toward the inward convex arc portion 36 from the hinge portion 32 (see FIG. 1). That is, the protrusion 81 is formed such that the portion closest to the inward convex arc portion 36 is the highest.

[0050] This protrusion 81 is formed by pressing down the top thereof with a die having an inclined surface after forming the spherical shell-shaped protruding end portion of the previous embodiment. Also in this protrusion 81, the rising bent portion 41 shown in FIG. 6(d) is formed as it is, and the cylindrical portion 42 is formed in a shape having different heights in the circumferential direction by the tapered surface 82.

[0051] By forming the upper surface of the protrusion 81 into the tapered surface 82 in this way, when pressed by the cylindrical opening device 66 of the beverage server, the highest position of the tapered surface 82 is pushed down, so that the pushing-down force is concentrated near the apex 36a of the inward convex arc portion 36, facilitating the initial score break (pop) and making it easier to open.

[0052] Note that, with respect to this protrusion 81, the protrusion 34 in FIG. 2 has a point as its apex, and when pressed down by the cylindrical opening device 66, the force is dispersed radially from the apex of the protrusion 34. Therefore, the pushing-down force on the apex 36a of the inward convex arc portion 36 is smaller than that of the protrusion 81, but since it is a mechanical push-down using the cylindrical opening device 66, the opening property is not impaired so much. Also, as shown in FIG. 10, when stacked in multiple sheets, they can be stably stacked parallel to each other, and the transportability is also good.

[0053] Figures 11 to 14 are modified examples of the concave or convex portions within the planned opening portion and the panel deposit portion outside the planned opening portion. In these figures, elements common to those in Figure 2 and the like are denoted by the same reference numerals to simplify the description. The convex portion 101 of this can lid 100 is composed of two types of convex portions, namely a first convex portion 102 and a second convex portion 103, both of which are formed to rise from the panel portion 11. The first convex portion 102 is composed of an elongated convex bead, surrounds approximately half of the protrusion 34, and both ends are formed to follow the arc-shaped portion 35 of the score 33 inside the arc-shaped portion 35. The second convex portion 103 is formed in a semi-circular shape so as to occupy approximately half of the region of the planned opening portion 31, the outer peripheral arc portion thereof is disposed inside the hinge portion 32, and extends along approximately half of the arc-shaped portion 35 of the score 33. Note that the second convex portion 103 is inclined so that the surface gradually becomes lower as it faces the hinge portion 32. Also, the protrusion 81 is the same as the protrusion 81 in FIGS. 9 and 10, and the linear end surface is inclined (however, in FIG. 13, for convenience of drawing, the tip surface is drawn flat).

[0054] Also in this can lid 100, by pushing the protrusion 81 downward, the score 33 can be broken and the planned opening portion 31 can be pushed in to open. Since the score 33 forms an inward convex arc portion 36 in the vicinity of the protrusion 81, the first breakage of the score 33, which requires the most force in the opening operation, can be facilitated. In that case, since the first convex portion 102 is formed around the protrusion 81, the side opposite to the inward convex arc portion 36 of the protrusion 81 is reinforced, the deflection when the protrusion 81 is pushed is small, and the initial opening can be facilitated. And the subsequent breakage (tear) of the score 33 can also be smoothly performed because the second convex portion 103 is disposed along the arc-shaped portion 35.

[0055] Even when a plurality of the can lids 100 are stacked, as shown in FIG. 14, since the can lids 100 are stacked substantially parallel to each other, the stacked state is stable, and it is possible to prevent the cans from being stacked in an inclined state and collapsing. Further, since no protrusions 81 or the like protrude above the can lid 100, it will not get caught during transportation, and the transportability is also good. Although two convex portions are given as examples of the convex portion 101, these convex portions may be concave portions, or may be composed of concave and convex portions. Further, there may be one convex portion or concave portion, and the concave portion or convex portion may have a bead shape.

Example

[0056] The can lids shown in FIGS. 3 and 9 were manufactured, and cans wound around a 211-diameter can body were manufactured. With the internal pressure shown in the table applied to the cans, the protrusions were pressed with a tensile-compressive universal testing machine (Autograph AG-X, 10N - 10kN, load cell MAX2kN) manufactured by Shimadzu Corporation, and the loads of POP and TEAR and the displacement of the pressing jig at that time were measured. As the pressing jig, a resin jig with an inner diameter of 12 mm and an outer diameter of 16 mm was attached and driven at a speed of 50 mm / second. Table 1 shows the results of the can lids shown in FIG. 3, and Table 2 shows the results of the can lids shown in FIG. 9.

[0057]

Table 1

[0058]

Table 2

[0059] When the internal pressure was 400 kPa, the POP value was 148.4 N for the can lid of FIG. 3 and 138.9 N for the can lid of FIG. 9. If the internal pressure is 400 kPa and 200 N or less, it is assumed that both can be used practically as server can lids. Also, it was shown that the POP value of the can lid of FIG. 9 is smaller than that of the can lid of FIG. 3. Note that the pressure resistance and the impact resistance against dropping were the same as those of ordinary can lids.

Explanation of Signs

[0060] 10 Can lid 11 Panel part 12 Annular recess 13 Countersink part 14 Chuck wall part 15 Shoulder part 16 Curled part 20 Can body 21 Body part 25 Flange part 31 Planned opening part 32 Hinge part 33 Score 34 Protrusion 35 Arc shape part 36 Inner convex arc part 37 Connecting arc part 38 Small arc part 51 Auxiliary score 52 Recess 65 Beverage server 66 Cylindrical opening device 67 Extraction pipe 80 Can lid 81 Protrusion 82 Tapered surface 100 Can lid 101 Convex part 102 First convex part 103 Second convex part

Claims

1. A disk-shaped panel portion is provided. The panel portion includes a planned opening portion and a panel outer peripheral portion. The planned opening portion includes a hinge portion, a score formed leaving the hinge portion, and a protrusion portion. The boundary between the planned opening portion and the panel outer peripheral portion consists of the hinge portion and the score. An inwardly convex arc portion that protrudes toward the center direction of the planned opening portion is formed in a part of the score. The protrusion portion is formed in the radially outer direction of the inwardly convex arc portion. The can lid is characterized by this.

2. The inwardly convex arc portion is arranged on the side opposite to the hinge portion via the center of the planned opening portion. The can lid according to claim 1 is characterized by this.

3. The score has a pair of arc-shaped portions formed on both sides of the planned opening portion so as to protrude outward in the radial direction of the planned opening portion. The inwardly convex arc portion is formed so as to connect both ends of both arc-shaped portions. The can lid according to claim 1 is characterized by this.

4. In the planned opening portion, a concave portion or a convex portion that extends along the arc-shaped portion to an intermediate position of the arc-shaped portion inside the arc-shaped portion and the hinge portion is formed. The can lid according to claim 3 is characterized by this.

5. The can lid according to claim 1 is characterized in that the planned opening portion is formed at the central portion in the radial direction.

6. The protrusion portion is characterized in that its protruding end portion is formed in a spherical shell shape. The can lid according to claim 1 is characterized by this.

7. The protrusion portion is formed on a tapered surface that is inclined with respect to the panel portion. The tapered surface is inclined such that the height from the surface of the panel portion gradually increases from the hinge portion toward the inwardly convex arc portion. The can lid according to claim 1 is characterized by this.

8. A panel deposit portion is formed in an annular shape so as to surround the outside of the planned opening portion. The can lid according to claim 1 is characterized by this.

9. A can in which the can lid according to any one of claims 1 to 8 is wound and tightened on a can body filled with contents.

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