Metal container

Abstract

To provide a metal container which is easily pulled out even when stacked and is hardly scratched.SOLUTION: The body portion includes a lower cylindrical portion continuous with the rising portion, a lower step portion continuous with an upper end of the lower cylindrical portion, and a tapered cylindrical portion continuous with an upper end of the lower step portion and having a tapered surface whose diameter gradually increases toward the opening portion, A connection portion between the rising portion and the lower cylindrical portion has a first curved surface having a convex outer surface, the lower step portion has a lower continuous curved surface having a second curved surface having a concave outer surface connected to the lower cylindrical portion and a third curved surface having a convex outer surface connecting the second curved surface and a lower end of the tapered cylindrical portion, and when the plurality of metal containers are stacked, the inner metal container is supported in a state where an outer surface of the first curved surface of the inner metal container and an inner surface of the lower continuous curved surface of the outer metal container are in contact with each other.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a metal container made of an aluminum alloy or the like. [Background technology]

[0002] When selling and serving beverages at events or when taking away beverages from stores, it is common to use thin, lightweight, mass-produced disposable cups made of paper or plastic. These cups are transported and stored in stacks for space efficiency, and are separated from the stack when used. These cups can also be made from metal. For example, Patent Document 1 discloses a tapered metal cup. This metal cup is made of aluminum and is described as being harder and more durable than plastic cups and also having excellent recyclability. It also describes that the inner diameter of the curled portion formed at the open end is between 2.0 inches and 5.0 inches.

[0003] The method for producing this metal cup also describes the following: a metal plate is punched and drawn to form a cup, and the cup is then ironed to form a cylindrical vertical-wall preform (DI process); the open end of the preform is rounded to form a curled portion, and then a stepwise drawing process is performed to form a vertically drawn cup having vertical wall sections of different heights and a continuously decreasing diameter from the curled portion to the bottom; a die having a tapered profile is then used to expand each of the vertical wall sections to form a tapered cup with each vertical wall section forming a tapered side wall; and finally, a dome portion is formed at the bottom of the cup. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-508874 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when multiple metal cups (metal containers) of Patent Document 1 are stacked, problems arise such as difficulty in separating one metal cup from multiple stacked metal containers, and the stacked metal containers are easily scratched.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a metal container that can be easily removed even when stacked and that is resistant to scratches. [Means for solving the problem]

[0007] As a result of intensive research, the present researchers have discovered that with conventional metal containers, when multiple bottomed cylindrical metal containers are stacked, the outer surface of the inner metal cup and the inner surface of the outer metal cup come into surface contact on the underside (bottom side) of the body of the metal containers, so that when trying to pull the inner (upper) metal cup out of the outer (lower) metal cup, the surface contact area acts like a wedge, making it difficult to pull out and causing scratches when forcibly pulling them out; in other words, this surface contact is the cause of the difficulty in pulling out the metal containers and the scratches caused by rubbing when pulling them out.The present researchers then conducted intensive research into the cause of this and discovered metal containers that are easy to pull out even when stacked and are less likely to get scratched, by changing the shape of the contact area between the outer surface of the body of the inner metal container and the inner surface of the body of the outer metal container to a shape that does not result in surface contact.

[0008] In other words, the metal container of the present invention is a cylindrical metal container with a bottom, and has a tapered body portion that expands in diameter from the bottom toward the opening, and the opening has a curled portion formed by rolling in the end portion including the edge, and the body portion has one or more convex outer surfaces that protrude outward along the circumferential direction, so that when multiple metal containers are stacked, the convex outer surface of the inner metal container contacts the inner surface of the metal container along the circumferential direction, and the inner metal container and the outer metal container can be arranged in a non-contact state at other parts.

[0009] When multiple metal containers are stacked, the inner metal container only contacts the outer metal container at the convex outer surface, making it easy to remove and less likely to be scratched when pulled out. However, if the inner metal container and the outer metal container come into contact at a part other than the convex outer surface due to slight tilting when stacked, they can still be separated radially, preventing a tight fit.

[0010] In this metal container, the body portion has a convex inner surface that protrudes inward along the circumferential direction, and when multiple metal containers are stacked, the convex outer surface of the inner metal container and the convex inner surface of the metal container come into contact along the circumferential direction. Since the convex surfaces are in contact with each other, it is easier to pull them out from the stuck state.

[0011] The present invention also provides a cylindrical metal container with a bottom, comprising a tapered body portion whose diameter increases from the bottom toward an opening, wherein the opening has a curled portion formed by rolling an end portion including an edge radially outward, the bottom portion having a tapered rising portion that connects from the outer peripheral edge of a rim portion that serves as a ground contact portion to the lowest end of the body portion, the body portion having a lower cylindrical portion that continues from the rising portion, a lower step portion that continues to the upper end of the lower cylindrical portion, and a tapered surface that continues to the upper end of the lower step portion and gradually increases in diameter toward the opening. The connecting portion between the rising portion and the lower cylindrical portion comprises a first curved surface having a convex outer surface, and the lower step portion comprises a lower continuous curved surface having a second curved surface having a concave outer surface that connects to the lower cylindrical portion and a third curved surface having a convex outer surface that connects the second curved surface to the lower end of the tapered cylindrical portion, and when multiple such metal containers are stacked, the inner metal container is supported with the outer surface of the first curved surface of the inner metal container in contact with the inner surface of the lower continuous curved surface of the outer metal container.

[0012] In the present invention, when multiple metal containers are stacked, the first curved surface and the lower continuous curved surface come into contact on the underside of the metal cup, and the tapered surface of the tapered cylindrical portion connected to the upper end of the lower step portion gradually expands in diameter toward the opening. Therefore, even when multiple metal containers are stacked, the tapered surfaces are spaced apart, preventing surface contact between the outer surface of the inner metal cup and the inner surface of the outer metal cup. This makes it easy to remove the uppermost (inner) metal cup from multiple stacked metal containers, and prevents the lower (outer) metal cups from separating in a row. Furthermore, because the inner metal cup and the outer metal cup do not come into surface contact, scratches are prevented from occurring during stacking and removal.

[0013] In a preferred embodiment of the metal container of the present invention, the body portion has an upper cylindrical portion continuous with the curled portion and an upper step portion continuous with the lower end of the upper cylindrical portion, the upper step portion consisting of an upper continuous curved surface having a fourth curved surface of a convex outer surface that connects to the lower end of the upper cylindrical portion and a fifth curved surface of a concave outer surface that connects the fourth curved surface with the upper end of the tapered tubular portion, the curled portion having an upper inner circumferential bent portion that continues with the upper end of the upper cylindrical portion and gradually increases in diameter as it extends upward, and when multiple such metal containers are stacked, the fourth curved surface of the upper continuous curved surface of the inner metal container is positioned opposite to the height position of the upper inner circumferential bent portion of the curled portion of the outer metal container.

[0014] When multiple metal containers are stacked, the fourth curved surface of the upper continuous curved surface of the inner metal container is positioned opposite the height of the upper inner bent portion of the curled portion of the outer metal container, and the upper inner bent portion of the curled portion is continuous with the upper end of the upper cylindrical portion and gradually expands in diameter upward. Therefore, even if the outer surfaces of these upper continuous curved surfaces come into contact with the outer surfaces of the upper inner bent portions of the curled portions, they do not come into surface contact. In other words, in the above-described embodiment, when the lower sides of the metal containers are supported, even if the outer surface of the upper continuous curved surface of the inner metal container comes into contact with the outer surface of the curled portion of the outer metal container at the top of the metal container, the curved surfaces prevent a tight fit between them, preventing the metal containers from becoming difficult to remove and preventing scratches from occurring during stacking and removal. Furthermore, when the outer surface of the upper continuous curved surface and the outer surface of the curled portion come into contact at the top of the metal container, the metal containers at the bottom are supported while preventing the stacked metal containers at the top from wobbling.

[0015] In a preferred embodiment of the metal container of the present invention, the radius of curvature of the outer surface of the first curved surface is 2.0 mm or more and 10.0 mm or less, the radius of curvature of the inner surface of the second curved surface is 2.0 mm or more and 24.0 mm or less, and the radius of curvature of the inner surface of the third curved surface is 3.0 mm or more and 26.0 mm or less.

[0016] In a preferred embodiment of the metallic container of the present invention, the radius of curvature of the outer surface of the fourth curved surface is 2.0 mm or more and 10.0 mm or less, and the radius of curvature of the outer surface of the fifth curved surface is 3.0 mm or more and 22.0 mm or less.

[0017] In a preferred embodiment of the metal container of the present invention, in a longitudinal cross section of the metal container along the can axis, the curled portion comprises the upper inner bent portion, an upper outer bent portion that is continuous with the outer peripheral end of the upper inner bent portion and forms a zenith fold portion between the upper inner bent portion and the upper outer bent portion and bends downward, a lower bent portion that is continuous with the outer peripheral end of the upper outer bent portion and is convex diagonally downward, and a curled end portion that is continuous with the lower bent portion, and the radius of curvature of the outer surface of the upper inner bent portion is 0.8 mm or more and 5.0 mm or less.

[0018] In a preferred embodiment of the metallic container of the present invention, the inclination angle of the tapered surface relative to a plane perpendicular to the can axis is 80° or more and 88° or less. If the inclination angle of the tapered surface relative to a plane perpendicular to the can axis is less than 80°, the body may widen too much toward the opening, increasing the capacity of the can and causing it to become unbalanced. If the inclination angle exceeds 88°, when multiple metal containers are stacked, the outer surface of the tapered surface of the inner metal container may come into surface contact with the inner surface of the tapered surface of the outer metal container. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a metal container that is easy to remove even when stacked and is resistant to scratches. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a front view of a metal cup (metallic container) according to a first embodiment of the present invention, with half of the cross section taken along the central axis. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a curled portion of the metal cup of FIG. 1. [Figure 3]FIG. 2 is a front view of a cylindrical body obtained by the drawing and ironing process, with half of the body taken as a vertical cross section centered on the central axis. [Figure 4] 2 is a diagram showing a state in which three metal cups shown in FIG. 1 are stacked together, and is a cross-sectional view showing only the right half of the central axis. FIG. [Figure 5] 5 is an enlarged cross-sectional view showing the bottom side of the metal cup in a state where three of the metal cups shown in FIG. 4 are stacked. FIG. [Figure 6] 5 is an enlarged cross-sectional view showing the opening side of a metal cup in a state where three metal cups shown in FIG. 4 are stacked. FIG. [Figure 7] This is a diagram showing three metal cups of the second embodiment stacked together, with their opening sides touching and their bottom sides not touching, and is a cross-sectional view showing only the right half of the center axis. [Figure 8] 1 is an X-ray image of the bottom side of three stacked metal cups in an embodiment of the present invention. [Figure 9] 10 is an X-ray image of the mid-abdominal side of three stacked metal cups in an embodiment of the present invention. [Figure 10] 10 is an X-ray image of the opening side of three stacked metal cups in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a metal container according to the present invention will be described with reference to the drawings. The metal container of the first embodiment is a wide-mouthed metal cup 1 as shown in Fig. 1. As shown in Fig. 1, this metal cup 1 is formed into a cylindrical shape with a bottom by press-forming a metal plate made of aluminum or an aluminum alloy, and has a tapered body 4 in which the diameter of the opening 3 is larger than the diameter of the bottom 2 and the diameter gradually increases from the bottom 2 toward the opening 3 as a whole, with a curled portion 5 formed at the opening 3 by rolling the end including the edge E radially outward. The radial center of this metal cup 1 is defined as a central axis C (can axis).

[0022] The bottom portion 2 has a shape that is continuous with a concavely curved dome portion 6, an inner tapered wall portion 7 that is continuous with the outer periphery of the dome portion 6 and gradually increases in diameter as it extends downward in the central axis direction, a rim portion 8 that is continuous with the outer periphery of the inner tapered wall portion 7 and forms the contact point when the metal cup 1 is placed on a table or the like, and a tapered rising portion 9 that connects the outer periphery of the rim portion 8 to the bottom end of the body portion 4. The dome portion 6 has a concave shape whose distance from the tip of the rim portion 8 is greatest at a position on the central axis C. The rim portion 8 is formed in a ring shape around the central axis C and has a curved surface that is convex downward from the central axis C, with its most protruding position forming the contact point. The outermost edge of the curved surface of the rim portion 8 is formed with a smaller diameter than the bottom end of the body portion 4, which has the smallest diameter, and the outermost edge of the rim portion 8 and the bottom end of the body portion 4 are connected by the tapered rising portion 9.

[0023] The body 4 has straight cylindrical portions 11, 12 formed along the central axis C near the bottom 2 and near the opening 3, with a small lower step 13 formed at the upper end of the lower cylindrical portion 11 continuing from the bottom 2, and a small upper step 14 also formed at the lower end of the upper cylindrical portion 12 continuing from the curled portion 5, and a tapered cylindrical portion 15 whose diameter gradually increases from bottom to top is formed between the upper end of the lower step 13 and the lower end of the upper step 14. Specifically, the body 4 has the lower cylindrical portion 11 continuing from the rising portion 9, the lower step 13 continuing from the upper end of the lower cylindrical portion 11, the tapered cylindrical portion 15 continuing from the upper end of the lower step 13 and having a tapered surface that gradually increases in diameter toward the opening 3, the upper cylindrical portion 12 continuing from the curled portion 5, and the upper step 14 continuing from the lower end of the upper cylindrical portion 12.

[0024] In addition, in a longitudinal cross section of the metal cup 1 along the can axis (center axis C), the connecting portion between the rising portion 9 and the lower cylindrical portion 11 comprises a first curved surface 91 having a convex outer surface. The radius of curvature R11 of the outer surface of this first curved surface 91 is 2.0 mm or more and 10.0 mm or less. The lower step portion 13 comprises a lower continuous curved surface 13A having a second curved surface 131 having a concave outer surface that connects to the lower cylindrical portion 11, and a third curved surface 132 having a convex outer surface that connects the second curved surface 131 to the lower end of the tapered tubular portion 15. The radius of curvature R12 of the inner surface of this second curved surface 131 is 2.0 mm or more and 24.0 mm or less, and the radius of curvature R13 of the inner surface of the third curved surface 132 is 3.0 mm or more and 26.0 mm or less. As will be described in more detail later, for example, when multiple metal cups 1 are stacked as shown in Figure 4, the outer surface of the first curved surface 91 of the inner metal cup 1 comes into contact with the inner surface of the second curved surface 131 of the lower continuous curved surface 13A of the outer metal cup 1, and the inner metal cup 1 is supported by this contact area.

[0025] In addition, in a longitudinal cross section along the can axis (central axis C) of the metal cup 1, the upper step portion 14 comprises an upper continuous curved surface 14A having a fourth curved surface 141 which is a convex outer surface connected to the lower end of the upper cylindrical portion 12, and a fifth curved surface 142 which is a concave outer surface connecting the fourth curved surface 141 with the upper end of the tapered tubular portion 15. The radius of curvature R14 of the outer surface of the fourth curved surface 141 is 2.0 mm or more and 10.0 mm or less, and the radius of curvature R15 of the outer surface of the fifth curved surface 142 is 3.0 mm or more and 22.0 mm or less. As will be described in more detail later, for example, as shown in Figure 4, when multiple metal cups 1 are stacked, the fourth curved surface 141 of the upper continuous curved surface 14A of the inner metal cup 1 is positioned opposite the height position of the curled portion 5 of the outer metal cup 1.

[0026] As for dimensions, the height H3 from the bottom surface to the lower end of the lower step portion 13 is 10 mm or more and 30 mm or less, and the length H4 from the upper end of the curled portion 5 to the upper end of the upper step portion 14 is 8 mm or more and 25 mm or less. Furthermore, the height H31 of the lower cylindrical portion 11 is 4 mm or more and 20 mm or less, and the height H41 of the upper cylindrical portion 12 is 4 mm or more and 20 mm or less.

[0027] Furthermore, in a longitudinal cross section of the metal cup 1 along the can axis (central axis C), the inclination angle θ2 of the tapered surface of the tapered tubular portion 15 with respect to a plane (horizontal plane) perpendicular to the can axis is set to be 80° or more and 88° or less. If the inclination angle θ2 of this tapered surface with respect to the plane perpendicular to the can axis is less than 80°, the body portion 4 may widen too much toward the opening 3, increasing the capacity of the can and causing its balance to deteriorate. If the inclination angle θ2 exceeds 88°, when multiple metal cups 1 are stacked, the outer surface of the tapered surface of an inner metal cup may come into surface contact with the inner surface of the tapered surface of an outer metal cup.

[0028] 2, in a cross section (longitudinal cross section) passing through the central axis C, the curled portion 5 is formed with an upper inner bent portion 71 that is continuous with the upper end of the upper cylindrical portion 12 of the body 4 and gradually increases in diameter as it extends upward, an upper outer bent portion 73 that is continuous with the outer peripheral end of the upper inner bent portion 71 and forms a zenith folded portion 72 between the upper inner bent portion 71 and the upper inner bent portion 71 and bends downward, a lower bent portion 74 that is continuous with the outer peripheral end of the upper outer bent portion 73 and is convex diagonally downward, and a curled end portion 75 that is continuous with the lower bent portion 74 and has an edge E. The intermediate position of the zenith folded portion 72, which is located from the rear half of the upper inner bent portion 71 to the front half of the upper outer bent portion 73, is located at the uppermost position of the curled portion 5, and the rear half of the lower bent portion 74 is located at the lowermost position of the curled portion 5.

[0029] In addition, a gap g is formed between the outer surface of the upper end portion of the upper cylindrical portion 12 of the body portion 4 continuous with the starting end portion of the curl portion 5 and the edge E on the outer surface side of the curl portion 5, and the curl end portion 75 including the edge E is inclined so as to have an upward gradient toward the central axis C with respect to a plane orthogonal to the central axis C of the body portion 4. This curl end portion 75 is continuous with the lower bent portion 74 and is slightly curved so as to be convex downward in a longitudinal section passing through the central axis C. However, since it is larger than the radius of curvature R5 of the lower bent portion 74 and has a shorter length, it may be regarded as extending substantially linearly from the end of the lower bent portion 74.

[0030] This curl portion 5 has, for example, a diameter (outer diameter of the open end portion) D1 of the curl portion 5 of 75 mm or more and 100 mm or less, a diameter D4 of the upper cylindrical portion 12 of 70 mm or more and 95 mm or less, a thickness T in the radial direction of the curl portion 5 of 1.8 mm or more and 5.0 mm or less, and a height W of the curl portion 5 along the central axis C of the metal cup 1 of 1.2 mm or more and 4.0 mm or less. In this case, W is smaller than T (W < T). Further, the gap g between the outer surface of the upper end portion of the upper cylindrical portion 12 of the body portion 4 and the edge E on the outer surface side of the curl portion 5 has a dimension B along a plane orthogonal to the central axis C of 0.1 mm or more and 2.0 mm or less, preferably 0.3 mm or more and 1.6 mm or less.

[0031] In addition, the height X along the central axis from the lower end of the curl portion 5 to the edge E on the outer surface side of the curl portion 5 is 0.1 mm or more and 2.0 mm or less, preferably 0.3 mm or more and 1.5 mm or less. In this case, X and B are set in a relationship of (1 / 20)×W < X < (1 / 2)×W and (1 / 20)×T < B < (1 / 2)×T with respect to the height W and width T of the curl portion 5.

[0032] Each bent portion has a radius of curvature on its outer surface. The radius of curvature R1 of the upper inner bent portion 71 is 0.8 mm to 5.0 mm. The upper outer bent portion 73 is broadly divided into two curvature portions, a front half portion and a rear half portion. The radius of curvature R2 of the front half portion is 1.0 mm to 3.0 mm, preferably 1.3 mm to 2.5 mm, and the radius of curvature R3 of the rear half portion is 1.3 mm to 5.0 mm, preferably 1.5 mm to 3.8 mm. The lower bent portion 74 is also broadly divided into two curvature portions, a front half portion and a rear half portion. The radius of curvature R4 of the front half portion is 0.5 mm to 2.5 mm. The radius of curvature R5 of the rear half portion is 0.8 mm to 10 mm, preferably 1.0 mm to 5.0 mm. The outer surface of the lowest end of the curled portion 5 is formed by the lower bent portion 74 with a radius of curvature R5. The inclination angle θ1 of the curled end 75 with respect to a plane perpendicular to the central axis C of the body 4 is set to be 5° or more and 80° or less, and preferably 10° or more and 50° or less.

[0033] Other dimensions are not necessarily limited, but for example, the diameter D2 of the ground contact portion is 45 mm or more and 60 mm or less, the overall height H1 is 80 mm or more and 180 mm or less, and the diameter D3 of the lower cylindrical portion 11 is 50 mm or more and 70 mm or less.

[0034] Next, a method for manufacturing this metal cup 1 will be described. This metal cup 1 is manufactured through a process including a cylinder-forming process in which a metal plate is drawn and ironed to form a bottomed cylindrical cylinder 21, a diameter-expanding process in which, after the cylinder-forming process, a plurality of punches with different outer diameters are used, starting with the smallest outer diameter, to press the punches into the cylinder 21 from the opening 22 side, gradually expanding the diameter of the body 23 of the cylinder 21 from the bottom 2 side toward the opening 22 side to form a tapered intermediate cylinder 50, and a curling process in which a curled portion 5 is formed at the open end of the tapered intermediate cylinder 50 formed in the diameter-expanding process. The processes will be described below in order.

[0035] [Cylinder formation process] The cylinder-forming process includes a cup-forming process in which an aluminum or aluminum alloy plate is punched and drawn to form a cup 25 that is shallower and has a larger diameter than the cylinder 21 to be formed in the next process, as shown in Fig. 3(a), and a drawing and ironing process in which the cup 25 is drawn and ironed to form a cylindrical cylinder 21 with a bottom that is smaller in diameter than the cup 25 and has a predetermined height as shown in Fig. 3(b). In this drawing and ironing process, the bottom 2 of the cylinder 21 is finished to the final shape of the bottom 2 of the metal cup 1, and has a dome portion 6, an inner tapered wall portion 7, a rim portion 8, and a tapered rising portion 9.

[0036] [Diameter expansion process] The diameter expansion process consists of multiple steps, and by sequentially repeating a step formation process in which a step is formed in the body 23 of the cylindrical body 21, the diameter of which is larger on the opening 22 side than on the bottom 2 side, and a shaping process in which the step is expanded and shaped into a tapered surface, the tapered intermediate cylindrical body 50 shown in Figure 3(c) is formed. In this case, after the lower step forming process, in which lower step 13 is formed at the bottom of cylindrical body 21, there is a first step forming process in which a first step is formed slightly above lower step 13, a first shaping process in which the first step is shaped, a second step forming process in which a second step is formed near the top end of the shaped surface, a second shaping process in which the second step is shaped, etc. After the initial lower step is formed, the step forming process and the shaping process are alternately performed to form one step and then shape the step into a tapered shape as a whole. Finally, at the top of cylindrical body 21, an upper step forming process is performed to form upper step 14, thereby completing the diameter expansion process.

[0037] [Curl forming process] After the diameter expanding step, the end portion including the edge E of the upper cylindrical portion 12' of the tapered intermediate cylinder 50 is folded back radially outward and wound, thereby forming the curled portion 5. This curled portion forming process is carried out in two stages: a pre-curling process in which the tip of the upper cylindrical portion 12' is spread radially outward at a specific radius of curvature, and a curling process in which, after the pre-curling process, the portion below the spread portion is rounded so as to invert the edge E.

[0038] The metal cup 1 manufactured in this manner has straight cylindrical portions 11, 12 of a certain length formed near the bottom 2 and the opening 3, and most of the body 4 therebetween is formed in a tapered shape that gradually increases in diameter from the bottom 2 toward the opening 3. In this manufacturing method, steps 52, 53 having a larger diameter on the opening 22 side than on the bottom 2 side of the cylindrical body 21 are formed, and then the steps 52, 53 are shaped into a tapered shape by expanding them, and this process is repeated to form the entire body 4 in a smooth tapered shape.

[0039] Since the metal material is pushed outward from the inner periphery in the radial direction, wrinkles are less likely to occur. Also, since the step is formed first and then tapered, cracks are less likely to occur compared to when the material is tapered without forming a step. This allows for the formation of a smoothly tapered body portion 4.

[0040] Furthermore, the bottom 2 of this metal cup 1 is the same as the bottom 2 formed in the bottomed cylindrical tubular body 21 formed in the initial stage, and the portion above this bottom 2 is expanded in diameter. Therefore, the process of forming the tubular body 21 (tubular body forming process) can be carried out using existing equipment for manufacturing beverage cans.

[0041] In addition, since the curling portion 5 is formed at the opening 3, the touch feeling is smooth. In particular, this curling portion 5 has a height W smaller than the width T (W < T), and the curling end portion 75 is inclined upward, so the lower lip touching this curling end portion 75 is also difficult to touch near the edge E. Therefore, there is no sense of discomfort and the mouthfeel is good. In this case, the relatively small height W being 1.2 mm or more and 4.0 mm or less also has the effect of improving the mouthfeel. If the angle θ1 of the curling end portion 75 is less than 5°, when the lower lip is applied to the curling portion 5, the vicinity of the edge E is also likely to touch the lip, so the goodness of the mouthfeel is reduced. If the angle θ1 exceeds 80°, the curling process becomes difficult.

[0042] Also, by setting the position of the edge E on the outer surface of the curling portion 5 to be (1 / 20)×W < X < (1 / 2)×W and (1 / 20)×T < B < (1 / 2)×T, it is possible to facilitate the discharge of water or the like that has entered the curling portion while ensuring a good mouthfeel. If X is less than or equal to (1 / 20)×W, or B is greater than or equal to (1 / 2)×T, there is a risk that the edge E will hit the lower lip when drinking a beverage. On the other hand, if X is greater than or equal to (1 / 2)×W, or B is less than or equal to (1 / 20)×T, it becomes difficult to discharge the water or the like that has entered the curling portion 5.

[0043] Moreover, since the radius of curvature R2 of the outer surface of the upper outer peripheral side bending portion 73 is 1.0 mm or more and 3.0 mm or less, and R3 is 1.3 mm or more and 5.0 mm or less, combined with the small height W of the curling portion 5, the rigidity of the curling portion 5 is high, and even when applied to the opening of a wide-mouthed cup, deformation or the like is prevented from occurring. Note that since a gap g is formed between the edge E of the curling portion 5 and the outer surface of the upper cylindrical portion 12 of the body portion 4, even when water or the like enters the curling portion 5 due to washing or the like, it can be quickly discharged. In this case, although the curling end portion 75 is inclined, the angle is small and the gap is large, so the internal water or the like can be easily discharged.

[0044] Furthermore, when a plurality of such metal cups 1 (for example, three) are stacked, the state shown in Fig. 4 is obtained. In this metal cup 1, the outer surface of the connecting portion between the rising portion 9 and the lower cylindrical portion 11 is formed as a convex first curved surface 91, and the lower step portion 13 is formed as a second curved surface 131 and a lower continuous curved surface 13A having the second curved surface 131 and a third curved surface 132, and the outer surface of the first curved surface 91 of the inner metal cup 1 is in contact with the inner surface of the lower continuous curved surface 13A of the outer metal cup 1. Specifically, as shown in Fig. 5, the outer surface (convex outer surface) of the first curved surface 91 of the inner metal cup 1 is in contact with the inner surface (convex inner surface) of the second curved surface 131 constituting the lower continuous curved surface 13A of the outer metal cup 1, and the inner metal cup 1 is supported by this contacting portion.

[0045] Furthermore, when the inner metal cup 1 and the outer metal cup 1 are in contact at the bottom side of the metal cup 1, the inner metal cup 1 and the outer metal cup 1 can be arranged in a non-contact state in other areas, and even if there is some contact in other areas, they can be separated radially. The upper step portion 14 of the metal cup 1 is formed of an upper continuous curved surface 14A having a fourth curved surface 141 and a fifth curved surface 142. As shown in FIG. 4, when a plurality of metal cups 1 are stacked, the fourth curved surface 141 of the upper continuous curved surface 14A of the inner metal cup 1 is disposed opposite to the height position of the upper inner bent portion 71 of the curled portion 5 of the outer metal cup 1. That is, as shown in FIG. 6, the outer surface of the fourth curved surface 141 constituting the upper continuous curved surface 14A of the inner metal cup 1 is capable of contacting the inner surface of the upper inner bent portion 71 of the curled portion 5 of the outer metal cup 1. However, a tight fit is not achieved. When viewed in vertical section, even if there is contact on one radial side at the height position of the upper inner bent portion 71 of the curled portion 5 of the outer metal cup 1, a gap is formed on the opposite side, and the contacting sides can be separated radially.

[0046] When multiple metal cups 1 are stacked, the first curved surface 91 and the lower continuous curved surface 13A come into contact on the underside of the metal cups 1, and the tapered surface of the tapered tubular portion 15 connected to the upper end of the lower step portion 13 gradually expands in diameter toward the opening 3. Therefore, even when multiple metal cups 1 are stacked, the tapered surfaces are spaced apart, preventing surface contact between the outer surface of the inner metal cup 1 and the inner surface of the outer metal cup 1. This makes it easy to remove the uppermost (inner) metal cup 1 from the stacked multiple metal cups 1, and prevents multiple lower (outer) metal cups 1 from separating in a row. Furthermore, since there is no surface contact between the inner metal cup 1 and the outer metal cup 1, scratches can be prevented from occurring when stacking or pulling out the cups.

[0047] Furthermore, when a plurality of metal cups 1 are stacked, the fourth curved surface 141 of the upper continuous curved surface 14A of the inner metal cup 1 is disposed opposite to the height position of the upper inner periphery bent portion 71 of the curled portion 5 of the outer metal cup 1, and the upper inner periphery bent portion 71 of the curled portion 5 is continuous with the upper end of the upper cylindrical portion 12 and gradually increases in diameter upward, so that even if the outer surfaces of these upper continuous curved surfaces 14A come into contact with the inner periphery of the upper inner periphery bent portion 71 of the curled portion 5, there is no surface contact. That is, in this embodiment, when a plurality of metal cups 1 are stacked and the lower sides of the metal cups 1 are supported, even if the outer surface of the upper continuous curved surface 14A of the inner metal cup 1 comes into contact with the outer surface of the curled portion 5 of the outer metal cup 1 on the upper side of the metal cup 1, since both are curved surfaces, these are prevented from fitting tightly together, which prevents the metal cups 1 from becoming difficult to remove and prevents scratches from occurring when stacking and pulling out. Furthermore, when the outer surface of the upper continuous curved surface 14A and the outer surface of the curled portion 5 are in contact on the upper side of the metal cup 1, the metal cup 1 can be supported on the lower side while preventing the metal cup 1 stacked on top from wobbling.

[0048] A gap is formed in the radial direction between the upper continuous curved surface of the inner metal cup 1 and the outer surface of the fourth curved surface 141 constituting 14A, which is the inner circumferential surface (surface facing radially inward) of the upper inner circumferential bent portion 71 of the curled portion 5 of the outer metal cup 1. The gap needs to be formed as the sum of both sides in the radial direction, and when viewed in vertical cross section, a gap may be formed on one radial side and contact may occur on the opposite side. Even if the opposite sides are in contact, either the inner or outer metal cup 1 can be moved radially within the gap to separate them, allowing them to be arranged in a non-contact state. In this case, the plate thickness t refers to the plate thickness near the opening 22 (usually referred to as the flange portion) when the bottomed cylindrical body 21 is formed as shown in Figure 3(b). If the gap is less than half the plate thickness t, and if the roundness of the metal cups 1 is low, the metal cups may fit together when stacked, making them difficult to pull. If it exceeds 40 times the plate thickness t, the metal cups may become unstable when stacked. It is preferable that this gap be 20 times or less the plate thickness t.

[0049] In addition, the above embodiment can be modified as appropriate without departing from the spirit of the present invention. In the first embodiment, when a plurality of metal cups 1 are stacked, the outer surface (convex outer surface) of the first curved surface 91 of the inner metal cup 1 comes into contact with the inner surface (convex inner surface) of the second curved surface 131 constituting the lower continuous curved surface 13A of the outer metal cup 1. However, if the radius of curvature of the inner surface of the third curved surface 132 constituting the lower continuous curved surface 13A is greater than the radius of curvature of the outer surface of the first curved surface 91, the outer surface (convex outer surface) of the first curved surface 91 of the inner metal cup 1 may come into contact with the inner surface (concave inner surface) of the third curved surface 132 of the outer metal cup 1. Furthermore, the outer surface (convex outer surface) of the first curved surface 91 of the inner metal cup 1 may come into contact with the inner surface of the tapered tubular portion 15 of the body portion 4.

[0050] Furthermore, when multiple metal cups 1 are stacked, the first curved surface 91 of the inner metal cup 1 and the lower continuous curved surface 13A of the outer metal cup 1 are in contact with each other at the bottom sides of the metal cups 1, but conversely, they may be in contact at the opening 3 side without contacting at the bottom sides. Figure 7 shows a second embodiment in which they are in contact at the opening 3 side without contacting at the bottom sides. In Figure 7, the same reference numerals as in the first embodiment are used for convenience. In other words, in this second embodiment, when multiple metal cups 1 are stacked, the outer surface (convex outer surface) of the upper step portion 14 of the inner metal cup 1 comes into contact with the inner surface (convex inner surface) of the upper inner peripheral bent portion 71 in the curled portion 4 of the outer metal cup 1, and on the bottom side, the outer surface of the first curved surface 91 of the inner metal cup 1 and the inner surface of the second curved surface 131 of the lower continuous curved surface 13A of the outer metal cup 1 are in a non-contact state.

[0051] Furthermore, in all of the above embodiments, the bottom portion has a rim portion 8 and a tapered rising portion 9, and the first curved surface 91 is continuous with the upper end of this rising portion 9, but the rim portion may be formed directly from the body portion without forming a rising portion and a first curved surface. When multiple metal cups are stacked and are to be in contact with each other on the bottom side, the convex outer surface of the rim portion may be configured to be in contact with the inner surface of the outer metal cup. In essence, when multiple metal cups (metal containers) are stacked, the convex outer surface of the inner metal cup should contact the inner surface of the outer metal cup at one location along the circumferential direction in the axial direction of the cans in a longitudinal cross section along the can axis. In this contact state, the inner metal cup is simply placed on the outer metal cup, so if the stacked metal cups are turned upside down, the inner metal cup will fall. However, a slight fit so that the inner metal cup can be easily removed by pulling it with a slight force is also considered to be contact in this invention. [Example]

[0052] Using the method described in the first embodiment, 300 metal cups made of aluminum alloy were manufactured, each having the following dimensions: H1 of 150 mm, H3 of 17.5 mm, H31 of 8.7 mm, H4 of 13.0 mm, H41 of 10.5 mm, D1 of 84 mm, D2 of 48 mm, D3 of 62 mm, D4 of 78 mm, θ2 of 87°, the radius of curvature R11 of the outer surface of the first curved surface of 5.6 mm, the radius of curvature R12 of the inner surface of the second curved surface of 17.7 mm, the radius of curvature R13 of the inner surface of the third curved surface of 19.5 mm, the radius of curvature R14 of the outer surface of the fourth curved surface of 7.4 mm, the radius of curvature R15 of the fifth curved surface of 14.2 mm, and the radius of curvature R1 of the outer surface of the upper inner bent portion of the curled portion of 1.4 mm. Three of these metal cups were then stacked, and the vicinity of the bottom, midsection, and opening of each metal cup was photographed using an X-ray fluoroscopy device (Shimadzu Corporation: SMX-1000PLUS). The photographed image of the vicinity of the bottom of the metal cup is shown in Figure 8, the photographed image of the vicinity of the midsection in Figure 9, and the photographed image of the vicinity of the opening in Figure 10.

[0053] 8 to 10, when multiple metal cups are stacked, the first curved surface and the lower continuous curved surface come into contact on the lower side (bottom side) of the metal cups, and the tapered surface of the tapered cylindrical portion connected to the upper end of the lower step portion gradually expands in diameter toward the opening. Therefore, even when multiple metal cups are stacked, the tapered surfaces are spaced apart, and surface contact between the outer surface of the inner metal cup and the inner surface of the outer metal cup is suppressed. Furthermore, when the metal cups are stacked, the contact portions of each are configured as curved surfaces, making it easy to remove the uppermost (inner) metal cup from the stacked multiple metal cups, and preventing the lower (outer) metal cups from separating in a row. Furthermore, because there is no surface contact between the inner metal cup and the outer metal cup, scratches are suppressed when stacking and removing the cups. [Explanation of symbols]

[0054] C Center axis (can axis) E-edge 1 metal cup (metal container) 2 bottom 3 Opening 4. Torso 5 Curl section 6 Dome section 7 Inner tapered wall 8 Rim 9 Rising section 91 First curved surface 11 Lower cylindrical part 12 Upper cylindrical part 13 Lower section 13A Lower continuous curved surface 131 Second curved surface 132 Third curved surface 14 Upper step 14A Upper continuous curved surface 141 Fourth curved surface 142 5th curved surface 15 Tapered cylindrical part 21 Cylinder 25 cups 50 Tapered intermediate cylinder 71 Upper inner bending part 91 First curved surface 131 Second curved surface 132 Third curved surface

Claims

1. A cylindrical metal container with a bottom, The tire has a tapered body portion whose diameter increases from the bottom portion toward the opening portion, and the opening portion has a curled portion formed by rolling an end portion including an edge radially outward, and the bottom portion has a tapered rising portion that connects from the outer peripheral end of the rim portion, which serves as the ground contact portion, to the lowest end of the body portion, the body portion has a lower cylindrical portion continuing from the rising portion, a lower step portion continuing from an upper end of the lower cylindrical portion, and a tapered tubular portion continuing from the upper end of the lower step portion and having a tapered surface whose diameter gradually increases toward the opening, a connecting portion between the rising portion and the lower cylindrical portion having a first curved surface with a convex outer surface, and a lower step portion having a lower continuous curved surface with a second curved surface with a concave outer surface that connects to the lower cylindrical portion and a third curved surface with a convex outer surface that connects the second curved surface to the lower end of the tapered tubular portion, wherein when a plurality of the metal containers are stacked, the metal containers support the inner metal containers with the outer surface of the first curved surface of the inner metal container in contact with the inner surface of the lower continuous curved surface of the outer metal container.

2. The metal container according to claim 1, characterized in that the body portion has an upper cylindrical portion continuous with the curled portion and an upper step portion continuous with the lower end of the upper cylindrical portion, the upper step portion consisting of an upper continuous curved surface having a fourth curved surface of a convex outer surface that is connected to the lower end of the upper cylindrical portion and a fifth curved surface of a concave outer surface that connects the fourth curved surface to the upper end of the tapered tubular portion, the curled portion having an upper inner circumferential bent portion that is continuous with the upper end of the upper cylindrical portion and gradually increases in diameter as it extends upward, and when a plurality of the metal containers are stacked, the fourth curved surface of the upper continuous curved surface of the inner metal container is positioned opposite to the height position of the upper inner circumferential bent portion of the curled portion of the outer metal container.

3. 3. The metal container according to claim 1, wherein the radius of curvature of the outer surface of the first curved surface is 2.0 mm or more and 10.0 mm or less, the radius of curvature of the inner surface of the second curved surface is 2.0 mm or more and 24.0 mm or less, and the radius of curvature of the inner surface of the third curved surface is 3.0 mm or more and 26.0 mm or less.

4. 4. The metal container according to claim 2, wherein the radius of curvature of the outer surface of the fourth curved surface is 2.0 mm or more and 10.0 mm or less, and the radius of curvature of the outer surface of the fifth curved surface is 3.0 mm or more and 22.0 mm or less.

5. In a longitudinal cross section of the metal container along the can axis, the curled portion has a zenith folded portion between the upper inner circumferential bent portion and the outer circumferential end of the upper inner circumferential bent portion.

5. The metal container according to claim 4, characterized in that it comprises an upper outer circumferential bent portion that is formed at an outer periphery and bent downward, a lower bent portion that is continuous with the outer peripheral end of the upper outer circumferential bent portion and is convex diagonally downward, and a curled end portion that is continuous with the lower bent portion, wherein the radius of curvature of the outer surface of the upper inner circumferential bent portion is 0.8 mm or more and 5.0 mm or less.

6. 6. The metal container according to claim 1, wherein the inclination angle of the tapered surface relative to a plane perpendicular to the can axis is 80° or more and 88° or less.

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