Can lid manufacturing method, can lid manufacturing apparatus, and can lid

Abstract

To provide a can lid manufacturing method, a can lid manufacturing device, and a can lid capable of improving breaking strength of a score with a simple structure.SOLUTION: A score forming step of forming a main score L4 for opening and an auxiliary score L4 formed on an inner peripheral side of the main score L5 by sandwiching the can lid blank Lb in a thickness direction by the punch 30 and the die 40, wherein in the score forming step, pressing of the can lid blank Lb by the auxiliary score-forming pressing part 32 of the punch 30 is started with a delay from start of pressing of the can lid blank Lb by the main score-forming pressing part 31 of the punch 30; While the can lid blank Lb is pressed by the pressing part 31 for the main score, compressive force for pressing the can lid blank Lb in the thickness direction is applied on the outer peripheral side of the L4 part of the main score.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a can lid manufacturing method, a can lid manufacturing device, and a can lid. [Background technology]

[0002] Conventionally, it has been generally known to use metal cans as containers for holding contents such as beverages, and can lids that constitute can containers are known to have scores formed on them for opening (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-047534 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in can lids with such opening scores formed, the scores may break unintentionally if the container is dropped, for example, and there is room for improvement in terms of the breaking strength of such scores.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a can lid manufacturing method, a can lid manufacturing apparatus, and a can lid that are simple in configuration and improve the breaking strength of the score. [Means for solving the problem]

[0006] One aspect of the can lid manufacturing method of the present invention is a can lid manufacturing method for manufacturing can lids, which includes a score forming process in which a main score for opening and an auxiliary score formed on the inner peripheral side of the main score are formed by clamping a can lid blank in the thickness direction with a punch and a die, and in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank with a delay after the main score pressing portion of the punch starts pressing the can lid blank, and while the main score pressing portion is pressing the can lid blank, a compressive force is applied on the outer peripheral side of the main score to press the can lid blank in the thickness direction, thereby solving the above problem. Another aspect of the can lid manufacturing method of the present invention is a can lid manufacturing method for manufacturing can lids, which includes a score forming step in which a main score for opening and an auxiliary score formed on the inner periphery of the main score are formed by clamping a can lid blank in the thickness direction with a punch and a die, the punch having a main score pressing portion and an auxiliary score pressing portion, the outer periphery corner of the lower end of the main score pressing portion having a smaller radius of curvature than the inner periphery corner of the lower end of the main score pressing portion, and in the score forming step, the auxiliary score pressing portion of the punch starts pressing the can lid blank after the main score pressing portion of the punch starts pressing the can lid blank, thereby solving the above problem. Another aspect of the can lid manufacturing method of the present invention is a can lid manufacturing method for manufacturing can lids, which includes a score forming process in which a main score for opening and an auxiliary score formed on the inner side of the main score are formed by clamping a can lid blank in the thickness direction with a punch and a die, the punch having a main score pressing portion and an auxiliary score pressing portion, the outer side surface of the main score pressing portion having a surface roughness greater than that of the inner side surface of the main score pressing portion, and in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after the main score pressing portion of the punch starts pressing the can lid blank, thereby solving the above problem. Another aspect of the can lid manufacturing method of the present invention is a can lid manufacturing method for manufacturing can lids, which includes a score forming process in which a main score for opening and an auxiliary score formed on the inner side of the main score are formed by clamping a can lid blank in the thickness direction with a punch and a die, the punch having a main score pressing portion and an auxiliary score pressing portion, the outer peripheral side of the main score pressing portion having a smaller inclination angle with respect to the pressing direction than the inner peripheral side of the main score pressing portion, and in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after the main score pressing portion of the punch starts pressing the can lid blank, thereby solving the above problem. Another aspect of the can lid manufacturing method of the present invention is a can lid manufacturing method for manufacturing can lids, which includes a score forming process in which a main score for opening and an auxiliary score formed on the inner peripheral side of the main score are formed by clamping a can lid blank in the thickness direction with a punch and a die, the punch having a main score pressing portion and an auxiliary score pressing portion, the main score pressing portion having a convex portion on its outer peripheral side, and in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after the main score pressing portion of the punch starts pressing the can lid blank, thereby solving the above problem. The can lid manufacturing apparatus of the present invention is a can lid manufacturing apparatus that manufactures can lids, and is equipped with a punch and a die for forming a main score for opening and an auxiliary score that is formed on the inner peripheral side of the main score by clamping a can lid blank in the thickness direction, and the punch has a main score pressing portion for forming the main score, and an auxiliary score pressing portion that is formed so as to start pressing the can lid blank after the main score pressing portion starts pressing the can lid blank, and the can lid manufacturing apparatus solves the above problem by further comprising means for applying a compressive force that presses the can lid blank in the thickness direction on the outer peripheral side of the main score while the main score pressing portion is pressing the can lid blank. The can lid of the present invention is a can lid that is attached to the mouth of a can body, and the top surface of the can lid is recessed with a main score for opening, an auxiliary score formed on the inner side of the main score, and an outer peripheral pressed portion formed on the outer side of the main score, and the auxiliary score and the outer peripheral pressed portion are shallower in depth in the thickness direction than the main score, thereby solving the above problem. In any of the above can lid manufacturing methods or can lid manufacturing devices, the punch may have an outer peripheral pressing portion on the outer periphery of the main score pressing portion, and in the score forming process, the outer peripheral pressing portion may start pressing the can lid blank after the main score pressing portion starts pressing the can lid blank. In any of the above can lid manufacturing methods or can lid manufacturing devices, the outer peripheral pressing portion may be formed adjacent to the main score pressing portion without any gap therebetween. In any of the above can lid manufacturing methods or can lid manufacturing apparatuses, the outer peripheral pressing portion and the auxiliary score pressing portion may be formed at a distance from the main score pressing portion, and the distance between the outer peripheral pressing portion and the main score pressing portion may be set to be equal to or less than the distance between the auxiliary score pressing portion and the main score pressing portion. In any of the above can lid manufacturing methods or can lid manufacturing devices, the punch may have an inner pressing portion formed adjacent to the main score pressing portion on the inner side thereof with no gap therebetween, and in the score forming process, the inner pressing portion may start pressing the can lid blank after the main score pressing portion starts pressing the can lid blank. In any of the above can lid manufacturing methods or can lid manufacturing devices, a biasing means may be arranged on the outer periphery of the main score pressing section, and in the score forming process, while the main score pressing section is pressing the can lid blank, the biasing means may apply a compressive force to the can lid blank in the thickness direction on the outer periphery of the main score. In any of the above can lid manufacturing methods or can lid manufacturing devices, the outer circumferential corner of the lower end of the main score pressing portion may have a smaller radius of curvature than the inner circumferential corner of the lower end of the main score pressing portion. In any of the above can lid manufacturing methods or can lid manufacturing devices, the outer peripheral side surface of the main score pressing portion may have a surface roughness greater than that of the inner peripheral side surface of the main score pressing portion. In any of the above can lid manufacturing methods or can lid manufacturing devices, the outer peripheral side surface of the main score pressing portion may have a smaller inclination angle with respect to the pressing direction than the inner peripheral side surface of the main score pressing portion. In any of the above can lid manufacturing methods or can lid manufacturing devices, the main score pressing portion may have a protrusion on its outer peripheral side surface. [Effects of the Invention]

[0007] According to the present invention, the breaking strength of the score can be improved with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a can lid according to one embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. 2 is an explanatory diagram showing a first embodiment of a score forming step and a score forming machine. [Figure 4] FIG. 3 is an explanatory diagram showing each step of the score formation process in the first embodiment. [Figure 5] FIG. 10 is an explanatory diagram showing a second embodiment of the scoring process and scoring machine. [Figure 6] FIG. 10 is an explanatory diagram showing a modified example of the scoring step and scoring machine. [Figure 7] FIG. 10 is an explanatory diagram showing a third embodiment of the scoring process and scoring machine. [Figure 8] FIG. 10 is an explanatory diagram showing a fourth embodiment of the score forming process and score forming machine. [Figure 9] FIG. 10 is an explanatory diagram showing a fifth embodiment of a score forming process and a score forming machine. [Figure 10] FIG. 10 is an explanatory diagram showing a sixth embodiment of the scoring process and scoring machine. [Figure 11]FIG. 13 is an explanatory diagram showing a seventh embodiment of the score forming process and score forming machine. DETAILED DESCRIPTION OF THE INVENTION

[0009] A can lid manufacturing apparatus 10 and a can lid manufacturing method according to one embodiment of the present invention will be described below with reference to the drawings. [Can lid]

[0010] First, the can lid L manufactured by the can lid manufacturing apparatus 10 and the can lid manufacturing method is made of a metal plate such as an aluminum alloy, and is wrapped around the mouth of a metal can body (not shown) filled with contents when manufacturing a can container containing contents.

[0011] As shown in Figure 1, the can lid L has a seaming portion L2 formed on the outer periphery of the center panel portion L1 and seamed around the can body, a tab L3 attached to the center panel portion L1, main scores L4 and auxiliary scores L5 formed in the center panel portion L1, a rib L6 formed on the inner periphery of the main scores L4 and auxiliary scores L5, and a step portion L7 formed on the outer periphery of the main scores L4 and auxiliary scores L5.

[0012] As shown in Figure 1, the main score L4 is formed to extend so as to define the intended opening area L8, and is a portion that functions as a weakened portion that breaks when the can lid L is opened, and is formed in the shape of a recessed groove that is recessed downward from the upper surface side of the center panel portion L1, as shown in Figure 3, etc. In addition, the auxiliary score L5 is a portion formed along the extension direction of the main score L4 at a position spaced apart from the inner periphery of the main score L4, and as shown in Figure 3, etc., is formed in the shape of a recessed groove recessed downward from the upper surface side of the center panel portion L1. As can be seen from FIG. 3 and other figures, the auxiliary score L5 is formed to have a shallower depth in the thickness direction (thickness direction of the center panel portion L1 of the can lid L) than the main score L4.

[0013] As shown in FIG. 1, the rib L6 is a portion where the plate material of the center panel portion L1 is deformed in the thickness direction on the inner peripheral side of the main score L4 and the auxiliary score L5. As shown in FIG. 1, the step portion L7 is a portion where the plate material of the center panel portion L1 is deformed in the thickness direction on the outer periphery side of the main scores L4 and the auxiliary scores L5. [Can lid manufacturing device and can lid manufacturing method]

[0014] Next, the can lid manufacturing apparatus 10 of this embodiment will be described below.

[0015] First, the can lid manufacturing device 10 manufactures can lids L by performing various processes on can lid blanks Lb (which have a seaming portion L2 formed on the outer periphery), and includes a protrusion forming machine (not shown) that forms tab protrusions on the center panel portion L1, a score forming machine 20 that forms scores L4 and L5 on the center panel portion L1, a step portion forming machine (not shown) that forms a step portion L7 on the center panel portion L1, and a tab attaching machine (not shown) that attaches tabs L3 to the tab protrusions.

[0016] The protrusion forming machine (not shown), score forming machine 20, and step forming machine (not shown) form tab protrusions, scores L4, L5, and step portions L7 in the center panel portion L1 by press processing the can lid blank Lb using a punch and a die.

[0017] As shown in FIG. 3 and other figures, the score forming machine 20 includes a punch 30 and a die 40 . As shown in Figure 3, etc., the punch 30 has a main score pressing portion 31 for forming the main score L4 by compression processing (coining processing), and an auxiliary score pressing portion 32 arranged on the outer periphery of the main score pressing portion 31 at a distance for forming the auxiliary score L5 by compression processing (coining processing).

[0018] In each embodiment described below, the score forming machine 20 forms the scores L4 and L5 and also bends the center panel portion L1 to form the rib L6 in the score forming process, and the punch 30 and the die 40 have a portion (not shown) for forming the rib L6 by bending the center panel portion L1. However, the formation of the rib L6 may be performed at a different time.

[0019] The can lid manufacturing method manufactures can lids L by performing various processes on the can lid blank Lb, and includes a protrusion forming process for forming tab protrusions on the center panel portion L1, a score forming process for forming scores L4 and L5 on the center panel portion L1, a step forming process for forming a step portion L7 on the center panel portion L1, and a tab attaching process for attaching the tab L3 to the tab protrusion.

[0020] In the score forming process, common to each of the embodiments described below, the can lid blank Lb is clamped in the thickness direction by the punch 30 and the die 40 to form scores L4 and L5 in the center panel portion L1, and the auxiliary score pressing portion 32 begins pressing the can lid blank Lb after the main score pressing portion 31 begins pressing the can lid blank Lb.

[0021] The scoring process and the first embodiment of the scoring machine 20 will be described below with reference to FIGS.

[0022] In the first embodiment, as shown in FIG. 3, an outer circumferential pressing portion 33 for forming an outer circumferential pressed portion L9 by compression processing (coining processing) is formed adjacent to the main score pressing portion 31 without any gap on the outer circumferential side of the main score pressing portion 31 of the punch 30.

[0023] In the first embodiment, as shown in Figures 3 and 4, during the score formation process, while the main score pressing section 31 is pressing the can lid blank Lb, a compressive force (pressing force) is applied to the can lid blank Lb in the thickness direction on the outer periphery of the main score L4. Specifically, as shown in Figure 4, the outer periphery pressing section 33 starts pressing the can lid blank Lb after the main score pressing section 31 starts pressing the can lid blank Lb (and after the auxiliary score pressing section 32 starts pressing the can lid blank Lb).

[0024] In this way, by applying a compressive force to the can lid blank Lb on the outer periphery of the main score L4 while the main score pressing portion 31 is pressing the can lid blank Lb, in the first embodiment, the tensile stress that occurs in the can lid blank Lb on the outer periphery of the main score L4 (main score pressing portion 31) during the formation of the main score L4 is alleviated, and tensile stress is prevented from remaining in the formed can lid L (can lid blank Lb), preventing the areas where the tensile stress remains from becoming unintended breaking areas when the can lid L is subjected to a dropping impact, etc., thereby improving the breaking strength of the score.

[0025] In other words, by applying a compressive force on (near) the outer periphery of the main score L4 (main score pressing portion 31) during score formation, the tensile stress generated in the can lid blank Lb on the outer periphery of the main score L4 (main score pressing portion 31) (particularly, near point A shown in Figure 4(c)) can be alleviated compared to when the compressive force is not applied. Furthermore, if the above-mentioned compressive force is not applied, tensile stress is likely to remain in the outer peripheral portion (point A shown in Figure 4(c)) of the lower side of the main score L4 (main score pressing portion 31). However, in the first embodiment, by applying compressive force to (near) the outer peripheral side of the main score L4 (main score pressing portion 31) when forming the score, it is possible to prevent tensile stress from remaining in the above-mentioned point A. Furthermore, when the above-mentioned compressive force is not applied, the tensile stress becomes greater on the outer side of the main score L4 than on the inner side, and the tensile stress is likely to remain at the above-mentioned point A. This is thought to be due to the fact that a compressive force is applied to (near) the inner side of the main score L4 (main score pressing portion 31) by the auxiliary score pressing portion 32 when the score is formed.

[0026] Next, a second embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0027] In the second embodiment, as shown in Figure 5, in addition to the outer pressing portion 33 formed in the same manner as in the first embodiment, an inner pressing portion 34 for forming an inner pressed portion L10 by compression processing (coining processing) is formed adjacent to the main score pressing portion 31 without any gap on the inner side of the main score pressing portion 31.

[0028] In the second embodiment, as shown in Figure 5, during the score formation process, while the main score pressing section 31 is pressing the can lid blank Lb, a compressive force is applied on the inner side of the main score L4 to press the can lid blank Lb in the thickness direction. Specifically, the inner side pressing section 34 starts pressing the can lid blank Lb at the same timing as the outer side pressing section 33 starts pressing the can lid blank Lb, but after the main score pressing section 31 starts pressing the can lid blank Lb (and the auxiliary score pressing section 32 starts pressing the can lid blank Lb).

[0029] Furthermore, as a modified example common to the first and second embodiments, as shown in Figure 6, the outer peripheral pressing portion 33 may be formed at a distance from the main score pressing portion 31, and in this case, it is preferable to set the distance S2 between the outer peripheral pressing portion 33 and the main score pressing portion 31 to be equal to or less than the distance S1 between the auxiliary score pressing portion 32 and the main score pressing portion 31.

[0030] The distance S1 between the auxiliary score pressing portion 32 and the main score pressing portion 31 is the distance between the upper end of the effective surface of the inner peripheral side of the main score pressing portion 31 (the surface that is located below the upper surface of the can lid blank Lb when the punch 30 is located at the bottom dead center, as shown in Figure 6, etc.) and the upper end of the effective surface of the outer peripheral side of the auxiliary score pressing portion 32. Similarly, the distance S2 between the outer peripheral pressing portion 33 and the main score pressing portion 31 is the distance between the upper end of the effective surface of the outer peripheral side surface of the main score pressing portion 31 and the upper end of the effective surface of the inner peripheral side surface of the outer peripheral pressing portion 33. The interval S1 is preferably set to 0.5 to 1.5 mm, and the interval S2 is preferably set to 0 to 1.5 mm (excluding 0 mm).

[0031] In addition, in the first and second embodiments, as a result of carrying out the score forming process as described above, as shown in Figure 1, a main score L4 for opening, an auxiliary score L5 formed on the inner side of the main score L4, and an outer peripheral pressed portion L9 formed on the outer peripheral side of the main score L4 are recessed on the upper surface of the can lid L (can lid blank Lb). These auxiliary scores L5 (auxiliary score pressing portion 32) and outer peripheral pressed portion L9 (outer peripheral pressing portion 33) are formed to extend along the extension direction of the main score L4 (main score pressing portion 31) so as to be aligned parallel (or nearly parallel) to the main score L4 (main score pressing portion 31), as shown in Figure 1. In the example shown in Figure 1, the auxiliary score L5 (auxiliary score pressing portion 32) and the outer peripheral pressed portion L9 (outer peripheral pressed portion 33) are formed on the inner or outer peripheral side of the main score L4 (main score pressing portion 31), side by side with the main score L4 (main score pressing portion 31) over the entire area (almost the entire area) in the extension direction of the main score L4 (main score pressing portion 31).However, at least one of the auxiliary score L5 (auxiliary score pressing portion 32) and the outer peripheral pressed portion L9 (outer peripheral pressed portion 33) may be formed so as to be side by side with the main score L4 (main score pressing portion 31) in only a partial area in the extension direction of the main score L4 (main score pressing portion 31). As shown in FIGS. 3 and 5, the auxiliary scores L5 are formed to be shallower in depth in the thickness direction than the main scores L4. Furthermore, as shown in Figures 3 and 5, the outer peripheral pressure-receiving portion L9 is formed to be shallower in the thickness direction than the main score L4 and the auxiliary score L5, thereby preventing deformation of the center panel portion L1 on the outer peripheral side of the main score L4 when the package is opened by breaking the main score L4.

[0032] In addition, in the second embodiment, as a result of carrying out the score forming process as described above, an inner peripheral pressed portion L10 is further recessed on the upper surface of the can lid L (can lid blank Lb) on the inner peripheral side of the main score L4, as shown in Figure 5. This inner circumference pressed portion L10 (inner circumference pressing portion 34) is formed to extend along the extension direction of the main score L4 (main score pressing portion 31) so as to be aligned parallel (or almost parallel) to the main score L4 (main score pressing portion 31). In the second embodiment, the inner circumference pressed portion L10 (inner circumference pressing portion 34) is formed on the inner circumference side of the main score L4 (main score pressing portion 31), side by side with the main score L4 (main score pressing portion 31) over the entire area (almost the entire area) in the extension direction of the main score L4 (main score pressing portion 31), but the main score L4 (main score pressing portion 31) may also be formed so as to be side by side with the main score L4 (main score pressing portion 31) in only a partial area in the extension direction of the main score L4. Furthermore, as shown in Figure 5, the inner pressed portion L10 is formed to have a shallower depth in the thickness direction than the main score L4 and the auxiliary score L5, and more specifically, its depth in the thickness direction is formed to be the same depth as that of the outer pressed portion L9.

[0033] Next, a third embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0034] In the third embodiment, as shown in Figure 7, a spring 35 serving as a biasing means is arranged on the outer periphery of the main score pressing section 31, and during the score formation process, while the main score pressing section 31 is pressing the can lid blank Lb (in this embodiment, for the entire time from the start of pressing to the end of pressing), the spring 35 applies a compressive force on the outer periphery of the main score L4 to press the can lid blank Lb in the thickness direction.

[0035] In the example shown in Figure 7, springs 35 are arranged on both the top and bottom sides of the can lid blank Lb to apply a compressive force to the can lid blank Lb, but the specific installation manner of the springs 35 is not limited to this. For example, the springs 35 may be arranged only on the top side of the can lid blank Lb, and the bottom side of the can lid blank Lb may be supported by a die 40 to apply a compressive force to the can lid blank Lb.

[0036] In addition, in this embodiment, multiple springs 35 are arranged side by side on the outer periphery of the main score L4 over the entire area (almost the entire area) in the extension direction of the main score L4, but the springs 35 may also be arranged so that they are lined up in only a partial area in the extension direction of the main score L4.

[0037] Furthermore, with regard to the positioning of the spring 35, it is preferable to position the spring 35 so that the distance S3 between the spring 35 and the main score pressing portion 31 is equal to or less than the distance S1 between the auxiliary score pressing portion 32 and the main score pressing portion 31, as shown in Figure 7.

[0038] The distance S3 between the spring 35 and the main score pressing portion 31 is the distance between the upper end of the effective surface of the outer peripheral side surface of the main score pressing portion 31 and the inner peripheral end of the area to which compression force is applied by the spring 35, as shown in Figure 7. The interval S3 is preferably set to 0 to 1.5 mm (including 0 mm).

[0039] In this third embodiment, too, by applying a compressive force to the outer peripheral side of the main score L4 (main score pressing portion 31) during score formation, the tensile stress that occurs in the can lid blank Lb on the outer peripheral side of the main score L4 (main score pressing portion 31) during the formation of the main score L4 can be alleviated and tensile stress can be prevented from remaining in the above-mentioned outer peripheral portion A.

[0040] In this embodiment, the biasing means that applies a compressive force to press the can lid blank Lb in the thickness direction has been described as being composed of a spring 35, but the specific form of the biasing means may be any that applies a compressive force to press the can lid blank Lb in the thickness direction.

[0041] Next, a fourth embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0042] In the fourth embodiment, as shown in Figure 8, the radius of curvature of the outer circumferential corner 31b at the lower end of the main score pressing portion 31 is set to be smaller than that of the inner circumferential corner 31a at the lower end of the main score pressing portion 31. The outer peripheral corners 31b may be formed in an angular shape (with a radius of curvature of 0 m) instead of being curved.

[0043] Next, a fifth embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0044] In the fifth embodiment, as shown in Figure 9, the outer peripheral side surface 31d (at least the effective surface) of the main score pressing portion 31 is set to have a rougher surface than the inner peripheral side surface 31c (at least the effective surface) of the main score pressing portion 31.

[0045] Next, a sixth embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0046] In the sixth embodiment, as shown in Figure 10, the inclination angle of the outer peripheral side surface 31d (at least the effective surface) of the main score pressing portion 31 with respect to the pressing direction (the direction in which the punch is inserted into the can lid blank Lb; in this embodiment, the thickness direction of the can lid blank Lb) is set to be smaller than the inclination angle of the inner peripheral side surface 31c (at least the effective surface) of the main score pressing portion 31 with respect to the pressing direction. The angle of inclination of the outer peripheral side surface 31d of the main score pressing portion 31 with respect to the pressing direction may be 0°.

[0047] Next, a seventh embodiment of the scoring process and scoring machine 20 will be described with reference to FIG.

[0048] In the seventh embodiment, as shown in Figure 1, the main score pressing portion 31 has one or more convex portions 31e on its outer side surface, so that the resistance when pressing the main score pressing portion 31 into the can lid blank Lb is greater on the outer side surface side than on the inner side surface side of the main score pressing portion 31.

[0049] In these fourth to seventh embodiments, when forming the score, a compressive force is applied to the outer peripheral side of the main score L4 (main score pressing portion 31) (i.e., the compressive force generated on the outer peripheral side is made greater than the compressive force generated on the inner peripheral side of the main score L4), thereby alleviating the tensile stress generated in the can lid blank Lb on the outer peripheral side of the main score L4 (main score pressing portion 31) during the formation of the main score L4 and preventing tensile stress from remaining in the above-mentioned location A.

[0050] The features of the fourth to seventh embodiments described above may be combined with the features of other embodiments such as the first to third embodiments or modifications.

[0051] The above describes in detail an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the present invention as described in the claims, such as by arbitrarily combining each configuration of the above or below embodiments and modified examples to form a can lid manufacturing apparatus 10 or a can lid manufacturing method.

[0052] For example, in the above-described embodiment, the can lid L is described as a stay-on-tab (SOT) type easy-open lid, but the specific form of the can lid L is not limited to this, and it may be configured, for example, as a full-open type easy-open lid.

[0053] Furthermore, in each of the above-described embodiments, the main score pressing portion 31, the auxiliary score pressing portion 32, the outer periphery pressing portion 33, and the inner periphery pressing portion 34 are described as being attached to the same support portion and moving together in the vertical direction, but at least one of these portions 31, 32, 33, and 34 may also be configured to be independently movable in the vertical direction. [Explanation of symbols]

[0054] 10...Can lid manufacturing equipment 20 Score Machine 30 Punch 31 Main score pressing part 31a: Inner corner 31b...Outer corner 31c Inner circumferential surface 31d... Peripheral side 31e ··· convex part 32 Auxiliary score pressing part 33 Outer periphery pressing portion 34 Inner pressure part 35 Spring (biasing means) 40 ··· Die L...Can lid L1 Center panel L2 Sealing section L3 tab L4 Main Score L5: Auxiliary score L6 Rib L7...Step part L8: Planned opening area L9: Pressed part on outer periphery L10: Inner pressed part

Claims

1. A can lid manufacturing method for manufacturing a can lid, a score forming step of forming a main score for opening a can lid blank and an auxiliary score formed on the inner periphery of the main score by sandwiching the can lid blank in the thickness direction with a punch and a die, a main score pressing portion of the punch that starts pressing the can lid blank after the main score pressing portion of the punch starts pressing the can lid blank; and a compressive force is applied to the outer periphery of the main score to press the can lid blank in the thickness direction while the main score pressing portion is pressing the can lid blank.

2. the punch has an outer circumferential pressing portion on the outer circumferential side of the main score pressing portion, 2. The can lid manufacturing method according to claim 1, wherein in the score forming process, the outer peripheral pressing portion starts pressing the can lid blank after the main score pressing portion starts pressing the can lid blank.

3. 3. The can end manufacturing method according to claim 2, wherein the outer peripheral pressing portion is formed adjacent to the main score pressing portion without any gap therebetween.

4. the outer circumferential pressing portion and the auxiliary score pressing portion are formed at intervals from the main score pressing portion, 3. The can lid manufacturing method according to claim 2, wherein the distance between the outer peripheral pressing portion and the main score pressing portion is set to be equal to or smaller than the distance between the auxiliary score pressing portion and the main score pressing portion.

5. the punch has an inner peripheral pressing portion formed adjacent to the main score pressing portion on the inner peripheral side thereof without any space therebetween, 3. The can lid manufacturing method according to claim 1, wherein in the score forming process, the inner peripheral pressing portion starts pressing the can lid blank after the main score pressing portion starts pressing the can lid blank.

6. A biasing means is disposed on the outer periphery of the main score pressing portion, 3. The can lid manufacturing method according to claim 1, wherein in the score forming process, while the main score pressing section is pressing the can lid blank, the pressing means applies a compressive force that presses the can lid blank in a thickness direction on the outer periphery of the main score.

7. 3. The can lid manufacturing method according to claim 1, wherein an outer corner of a lower end of the main score pressing portion has a smaller radius of curvature than an inner corner of a lower end of the main score pressing portion.

8. 3. The can end manufacturing method according to claim 1, wherein the outer peripheral side surface of the main score pressing portion has a rougher surface than the inner peripheral side surface of the main score pressing portion.

9. 3. The can end manufacturing method according to claim 1, wherein an outer peripheral side surface of the main score pressing portion has a smaller inclination angle with respect to the pressing direction than an inner peripheral side surface of the main score pressing portion.

10. 3. The can lid manufacturing method according to claim 1, wherein the main score pressing portion has a protrusion on its outer peripheral side surface.

11. A can lid manufacturing method for manufacturing a can lid, a score forming step of forming a main score for opening a can lid blank and an auxiliary score formed on the inner periphery of the main score by sandwiching the can lid blank in the thickness direction with a punch and a die, The punch has a main score pressing portion and an auxiliary score pressing portion, an outer circumferential corner of a lower end of the main score pressing portion has a smaller radius of curvature than an inner circumferential corner of a lower end of the main score pressing portion; A can lid manufacturing method characterized in that, in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after a delay from when the main score pressing portion of the punch starts pressing the can lid blank.

12. A can lid manufacturing method for manufacturing a can lid, a score forming step of forming a main score for opening a can lid blank and an auxiliary score formed on the inner periphery of the main score by sandwiching the can lid blank in the thickness direction with a punch and a die, The punch has a main score pressing portion and an auxiliary score pressing portion, The outer peripheral side surface of the main score pressing portion has a surface roughness greater than that of the inner peripheral side surface of the main score pressing portion, A can lid manufacturing method characterized in that, in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after a delay from when the main score pressing portion of the punch starts pressing the can lid blank.

13. A can lid manufacturing method for manufacturing a can lid, a score forming step of forming a main score for opening a can lid blank and an auxiliary score formed on the inner periphery of the main score by sandwiching the can lid blank in the thickness direction with a punch and a die, The punch has a main score pressing portion and an auxiliary score pressing portion, an outer peripheral side surface of the main score pressing portion has a smaller inclination angle with respect to the pressing direction than an inner peripheral side surface of the main score pressing portion; A can lid manufacturing method characterized in that, in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after a delay from when the main score pressing portion of the punch starts pressing the can lid blank.

14. A can lid manufacturing method for manufacturing a can lid, a score forming step of forming a main score for opening a can lid blank and an auxiliary score formed on the inner periphery of the main score by sandwiching the can lid blank in the thickness direction with a punch and a die, The punch has a main score pressing portion and an auxiliary score pressing portion, The main score pressing portion has a convex portion on its outer peripheral side surface, A can lid manufacturing method characterized in that, in the score forming process, the auxiliary score pressing portion of the punch starts pressing the can lid blank after a delay from when the main score pressing portion of the punch starts pressing the can lid blank.

15. A can lid manufacturing apparatus for manufacturing can lids, The can lid blank is sandwiched in a thickness direction, and a punch and a die are provided for forming a main score for opening the can and an auxiliary score formed on an inner peripheral side of the main score, the punch has a main score pressing portion for forming a main score, and an auxiliary score pressing portion formed to start pressing the can lid blank with a delay after the main score pressing portion starts pressing the can lid blank, The can lid manufacturing apparatus is characterized in that it further includes a means for applying a compressive force that presses the can lid blank in a thickness direction on the outer peripheral side of the main score while the main score pressing section is pressing the can lid blank.

16. A can lid to be attached to the mouth of a can body, The upper surface of the can lid is recessed with a main score for opening the can, an auxiliary score formed on the inner periphery of the main score, and an outer periphery-side pressed portion formed on the outer periphery of the main score, The can lid is characterized in that the auxiliary scores and the outer peripheral pressed portions are shallower in depth in the thickness direction than the main scores.

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