Can body

Abstract

To ensure pressure resistance and drop strength while maintaining a predetermined filling volume of content.SOLUTION: A bottomed cylindrical aluminum alloy can body has a can bottom 11 and a can trunk 12. The can bottom has a dome portion 111 provided at the center of the can bottom and an annular salient 112 provided at the outer edge of the dome portion. The annular convex portion is provided continuously on the dome portion and includes a recess 112A having a curved surface convex in the radial direction outwardly of the can trunk, a ground portion 112B supporting the can body, and an inner peripheral wall 112C extending from the ground portion to the recess. The outer diameter of the can trunk is 50 mm or more and 59 mm or less, and the height from the ground portion to the top of the can body is 120 mm or more and 190 mm or less in height. The can body has a recess depth of 0.5 mm or more and 0.8 mm or less, and a ground diameter φ of 44.0 mm or more and 47.0 mm or less in a longitudinal sectional view including the can axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , , , , , , , , , , , , , , ,

[0005]

[0001] The present invention relates to a can body, and particularly to a can body with a bottom reform applied to the can bottom.

Background Art

[0002] Conventionally, an aluminum alloy drawn and ironed can (two-piece can) is known as a container for filling contents such as beverages. The can body constituting the aluminum alloy drawn and ironed can is obtained by punching a plate material made of aluminum alloy into a circular shape, performing a drawing process to form it into a bottomed cylindrical cup member with a shallow depth, and then performing a re-drawing and ironing process on the cup member to integrally form the can bottom and the can body.

[0003] In such a can body, thinning of the plate thickness of the can body is required from the perspective of resource conservation. Particularly, when the contents are carbonated beverages or the like, the can bottom is devised to ensure sufficient pressure resistance even with a thinned can body. Specifically, a dome portion with a central portion recessed toward the inside of the can body and an annular convex portion are provided around the dome portion on the can bottom, and a bottom reform is applied to the annular convex portion to ensure the pressure resistance accompanying the thinning (for example, Patent Document 1). Also, in such a can body, in order to be distributed in the market, it is required to ensure sufficient drop strength against the impact of dropping (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0006] This invention has been made in view of the above circumstances, and one of its objectives is to solve the problems described above. Specifically, this invention aims to ensure pressure resistance and drop strength while ensuring a predetermined amount of contents to be filled. [Means for solving the problem]

[0007] One aspect of the present invention is a bottomed cylindrical aluminum alloy can body having a can bottom and a cylindrical can body centered on a can axis extending from the outer circumference of the can bottom along the can axis, wherein the can bottom has a dome portion provided in the center of the can bottom and an annular projection that is continuous with the outer edge of the dome portion and protrudes annularly outward along the can axis, the thickness of the aluminum alloy on the can axis in the dome portion is 0.18 to 0.26 mm, the annular projection includes a recess portion provided continuously with the dome portion and having a curved surface that is convex radially outward of the can body, a ground portion that supports the can body and an inner circumferential wall portion extending from the ground portion to the recess portion, and the ground portion has the A first convex curved surface is formed on the side closer to the can axis and a second convex curved surface is formed on the side further away from the can axis, flanking the portion that protrudes most downward in the can axis direction at the ground contact point. The inner circumferential wall has an inclined surface. The outer diameter of the can body is in the range of 50 mm to 59 mm. The can height from the ground contact point to the upper end of the can body is in the range of 120 mm to 190 mm. In a longitudinal cross-sectional view including the can axis, the recess depth is 0.5 mm to 0.9 mm. The ground contact diameter is φ44.0 mm to 47.0 mm. The radius of curvature of the first convex curved surface is 0.4 mm to 0.7 mm, and the radius of curvature of the second convex curved surface is 1.6 mm to 2.2 mm. In the inner peripheral wall portion The present invention provides a can body in which the angle between the inclined surface and the can axis is 15° or more and 30° or less. Here, the recess depth is the radial distance between the part of the outer surface of the can body in the recess portion that is furthest from the can axis and the part of the outer surface of the can body in the ground portion that is closest to the can axis, and the ground diameter is the diameter of the part of the ground portion that protrudes the most downward toward the can axis. [Effects of the Invention]

[0008] According to the present invention, it is possible to ensure pressure resistance and drop resistance while securing a predetermined amount of contents. [Brief explanation of the drawing]

[0009] [Figure 1] This is a longitudinal cross-section of the can body along the can axis. [Figure 2]Figure 1 is a magnified cross-sectional view of the bottom of the can body shown. [Figure 3] This is an enlarged cross-sectional view of the bottom of a can according to a modified example 1 of an aluminum alloy can made by drawing and ironing according to an embodiment of the present invention. [Figure 4] This is an enlarged cross-sectional view of the bottom of a can according to a modified example 1 of an aluminum alloy can made by drawing and ironing according to an embodiment of the present invention. [Figure 5] This table shows the test results of dropping aluminum alloy cans with varying contact diameters, illustrating examples and comparative examples of the aluminum alloy cans according to the embodiment of the present invention. [Figure 6] This table shows the test results of dropping aluminum alloy cans with varying recess depths, illustrating examples and comparative examples of the aluminum alloy cans according to the embodiment of the present invention. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the same reference numerals indicate parts with the same function, and redundant explanations in each figure will be omitted as appropriate.

[0011] Figure 1 is a longitudinal cross-sectional view of the can body 10 along the can axis O, showing a schematic representation of the can body 10. Note that in Figure 1, the cross-sectional shape is shown as a line diagram, omitting the description of the plate thickness of the can body 10. As shown in Figure 1, the can body 10 is formed in a bottomed cylindrical shape, having a can bottom 11 and a cylindrical can body 12 centered on the can axis O, which extends from the outer circumference of the can bottom 11 along the can axis O.

[0012] The can bottom 11 comprises a dome portion 111 and an annular projection 112. The dome portion 111 is located in the center of the can bottom 11, and the annular projection 112 is continuous with the outer peripheral edge of the dome portion 111 and protrudes annularly outward from the can body 10 along the direction of the can axis O, supporting the can body 10. The annular convex portion 112 is provided continuously with the dome portion 111, and has a recess portion 112A having a curved surface that protrudes outward in the radial direction of the can body 10, a grounding portion 112B that supports the can body 10, and an inner peripheral wall portion 112C that extends from the grounding portion 112B to the recess portion 112A (see FIG. 2).

[0013] (Embodiment) The can body according to the embodiment of the present invention is, for example, a drawn and ironed can made of an aluminum alloy. The can body according to the present embodiment is a drawn and ironed can made of an aluminum alloy, has the same configuration as the can body 10 shown in FIG. 1, and has optimized shapes and dimensions of each part. Therefore, hereinafter, the shape and dimensions of the can body 10 as a drawn and ironed can made of an aluminum alloy according to the present embodiment will be described while also referring to FIG. 1.

[0014] The can body 10 as a drawn and ironed can made of an aluminum alloy is obtained, for example, by punching a plate material made of an aluminum alloy into a circular shape, performing a drawing process to form it into a bottomed cylindrical cup member, and then performing a redrawing and ironing process on the cup member to integrally form the can bottom 11 and the can body 12, and then trimming, necking, and flanging the open end of the can body 12.

[0015] The can body 10 has a can bottom 11 and a cylindrical can body 12 centered on the can axis O that extends along the can axis O from the outer periphery of the can bottom 11, and forms a bottomed cylindrical shape by the can bottom 11 and the can body 12. The can bottom 11 and the can body 12 have the same shape over the entire circumference around the can axis O.

[0016] The can height of the can body 10 from the grounding portion (described later) of the can bottom 11 to the upper end of the can body 12 is within the range of 120 mm or more and 190 mm or less, and in the example shown in FIG. 1, it is 155.0 mm. The outer diameter of the can body 12 is within the range of 50 mm or more and 59 mm or less, and in the example shown in FIG. 1, it is 57.2 mm.

[0017] FIG. 2 shows an enlarged cross-sectional view for explaining the can bottom 11. FIG. 2 shows a partially enlarged cross-sectional view of the can bottom 11 shown in FIG. 1. The bottom 11 of the can includes a dome portion 111 and an annular convex portion 112. As shown in FIG. 2, the dome portion 111 is provided at the central portion of the bottom 11 of the can, and has a plurality of curved surfaces including a dome-shaped concave curved surface that is recessed toward the inner side of the can body 12 along the can axis O direction. In the example shown in FIG. 1, the dome portion 111 is configured to include two curved surfaces, a first dome 111A and a second dome 111B, and a tapered portion 111C.

[0018] The first dome 111A has a concave curved surface with a radius of curvature R1 that is recessed toward the inner side of the can body 12 along the can axis O at the central portion of the bottom 11 of the can. Further, the second dome 111B is located around the first dome 111A, is continuously provided on the radially outer side of the outer peripheral edge of the first dome 111A, and has a concave curved surface with a radius of curvature R2 that is recessed toward the inner side of the can body 12. The radius of curvature R2 of the second dome 111B is smaller than the radius of curvature R1 of the first dome 111A.

[0019] The thickness of the aluminum alloy on the can axis O of the first dome 111A (hereinafter, simply referred to as "the thickness of the aluminum alloy") is preferably 0.18 or more and 0.26 mm or less. When the thickness of the aluminum alloy is too small, the occurrence of breakage of the can body, etc. increases at the stage of re-drawing and ironing processes, and there is a risk of a decrease in the yield rate. On the other hand, when it is too large, the amount of material used increases, so both are contrary to the demand for resource saving. Therefore, by setting the thickness of the aluminum alloy within the above range, the can body can be thinned to achieve resource saving, and breakage of the can body, etc. can be suppressed to improve the yield rate.

[0020] The dome portion 111 may have a plurality of curved surfaces with different radii of curvature as in the example of FIG. 1. Further, it can be a curved surface in which the radius of curvature gradually changes continuously, or can be a curved surface with a single radius of curvature. In addition, known dome shapes can also be applied.

[0021] The tapered portion 111C is a surface provided on the outer circumference of the second dome 111B, with one end continuous with the outer edge of the second dome 111B and the other end continuous with the recess portion 112A described later, so that it is a tapered surface that gradually widens in diameter from the second dome 111B toward the recess portion 112A. The tapered portion 111C may be straight in a longitudinal cross-sectional view including the can shaft O, or it may be a curved surface that protrudes toward the inside or outside of the can body 10.

[0022] The annular projection 112 protrudes in an annular shape from the outer periphery of the dome portion 111 toward the outside of the can body 10 along the direction of the can axis O. In the example shown in Figure 2, the annular projection 112 has a recess portion 112A, a ground portion 112B, and an inner circumferential wall portion 112C.

[0023] The recess portion 112A is provided so as to be continuous with the outer edge of the dome portion 111 and has a curved surface that is convex radially outward on the can body 10. Preferably, the radius of curvature of the curved surface in the recess portion 112A is 0.3 mm or more and 1.2 mm or less. Preferably, the height of the recess portion 112A, that is, the distance in the direction of the can axis O from the contact point 113 of the contact portion 112B (the part of the contact portion 112B that protrudes the most downward in the direction of the can axis O and contacts the contact surface G) to the part of the outer surface of the can body 10 in the recess portion 112A that is furthest from the can axis O is 1 mm or more and 4 mm or less. This ensures the capacity and pressure resistance. The curved surface in the recess portion 112A may have multiple curved surfaces, each with a different radius of curvature of 0.3 mm or more and 1.2 mm or less.

[0024] When the can body 10 is placed on a substantially horizontal ground surface (horizontal plane) G, the ground contact portion 113 of the ground contact portion 112B contacts the ground surface G and supports the can body 10. The ground contact portion 112B has two convex curved surfaces on both sides of the ground contact portion 113. Specifically, as shown in Figures 1 and 2, the contact portion 112B has a first convex curved surface portion 113A on the side closer to the can shaft O than the contact portion 113, and a second convex curved surface portion 113B on the side further from the can shaft O than the contact portion 113. Preferably, the radius of curvature R3 of the first convex curved surface portion 113A is 0.4 mm or more and 0.7 mm or less, and the radius of curvature R4 of the second convex curved surface portion 113B is 1.6 mm or more and 2.2 mm or less. This ensures drop strength.

[0025] The inner circumferential wall portion 112C is provided between the grounding portion 112B and the recess portion 112A, and is inclined so as to gradually decrease in diameter from the recess portion 112A toward the grounding portion 112B along the direction of the can axis O. The inclination angle of the inner circumferential wall portion 112C, that is, the angle between the inner circumferential wall portion 112C and the can axis O, is preferably 15° or more and 30° or less.

[0026] Preferably, the annular projection 112 is formed such that, in a longitudinal cross-sectional view including the can shaft O shown in Figure 1, the recess depth is 0.5 mm or more and 0.9 mm or less, and the contact diameter is φ44.0 mm or more and 47.0 mm or less. Here, the recess depth d1 is the radial distance between the part of the outer surface of the can body 10 in the recess portion 112A that is furthest from the can axis O and the part of the outer surface of the can body 10 in the ground portion 112B that is closest to the can axis O. Furthermore, the grounding diameter is the diameter of the grounding portion 113 in the grounding section 112B. In the example in Figure 1, the recess depth d1 is 0.7 mm and the grounding diameter is φ45.5 mm. The above configuration allows for a balance between capacity, pressure resistance, and drop resistance, and ensures these qualities more effectively.

[0027] The can body 12 is formed in a cylindrical shape centered on the can axis O, which extends from the outer circumference of the can bottom 11 along the can axis O. The neck portion 121, provided at the upper end of the can body 12, is formed such that the outer diameter of the can body 12 gradually decreases as it extends upward along the can axis O. A can lid (not shown) with a smaller diameter than the can body 12 is provided on the neck portion 121. In the example shown in Figure 1, the minimum outer diameter of the neck portion 121 is 52.4 mm.

[0028] The neck portion 121 has a concave curved surface 121A at its upper end that is recessed inward in the radial direction of the can body 10 with a radius of curvature r1, and a convex curved surface 121B at its lower end that is convex outward in the radial direction of the can body 10 with a radius of curvature r2. Furthermore, between the concave curved surface 121A at the upper end and the convex curved surface 121B at the lower end, there is a concave curved surface 121C with a radius of curvature r3 that is recessed inward in the radial direction of the can body 10. A flange portion 123 is formed at the open end of the can body 10, i.e., the upper end of the neck portion 121. In the example shown in Figure 1, the radius of curvature r1 is 1.5 mm, the radius of curvature r2 is 5.0 mm, and the radius of curvature r3 is 10.0 mm. The values ​​of each radius of curvature are merely examples and are not limited to these values.

[0029] (Variation 1) The following describes a modified example 1 of the can body according to the above embodiment. Figure 3 shows an enlarged view of the bottom 11 of the can body in a longitudinal cross-sectional view along the can axis O of the can body according to this modified example 1 (the can axis O is not shown in Figure 3). As shown in Figure 3, compared to the can body according to the embodiment described above, in this modified example, the radius of curvature of the recess portion 112A is larger, and the distance of the inner circumferential wall portion in the vertical cross-sectional view is shorter.

[0030] To obtain the annular protrusion 112 shown in Figure 3, for example, bottom reform is performed using a predetermined reforming roll 20 as shown in Figure 4. That is, the reforming roll 20 is pressed radially outward against the annular protrusion extending outward from the second dome 111B of the dome portion 111 along the direction of the can axis O, thereby deforming the annular protrusion. As a result, a recess portion 112A is formed according to the shape of the reforming roll 20 and the amount of pressure applied, and a tapered portion 111C is formed on the upper side of the recess portion 112A, and an inner circumferential wall portion 112C is formed on the lower side of the recess portion 112A.

[0031] In this modified example, we have described an example of performing bottom reform by forming an annular protrusion using a reforming roll, but the method of performing bottom reform is not limited to this, and other methods can be used as appropriate.

[0032] Figures 5 and 6 are tables showing the results of drop tests for the can body 10 with adjusted dimensions for each part. Figures 5 and 6 show the results of two types of drop tests: a single-unit drop test and a case drop test. Each drop test was conducted under the following conditions.

[0033] (1) Single unit drop test One example is a test in which a can 10, filled with 335 ml of carbonated water, sealed with a lid, and thoroughly shaken, was dropped on its own.

[0034] In the single-unit drop test, the drop surface was a gray cast iron block with a top surface machined to be a flat surface with a 10° inclination angle, on which a single sheet of corrugated cardboard material used for packaging product cans was placed. The can body 10 was then dropped from a height such that the shortest distance from the contact point 112B to the drop surface was 20 cm, with the contact point 112B facing downwards and the can axis O aligned vertically.

[0035] (2) Case drop test As an example, one test involved filling a can 10 with 355 ml of carbonated water and sealing it with a can lid, then placing 24 of these cans into a rectangular cardboard packaging carton used for transporting product cans, shaking them thoroughly, and finally dropping them.

[0036] In the case drop test, the drop surface was a 20mm thick dull-finished steel plate made of SPCC placed on a horizontal concrete ground. A corrugated cardboard carton for packaging was placed on this drop surface with the contact portion 112B of the can body 10 contained inside facing downwards, and the longitudinal direction of the corrugated cardboard carton was tilted 20° from the horizontal. The carton was then dropped from a height such that the shortest distance between the corrugated cardboard carton and the steel plate was 15cm.

[0037] The tables in Figures 5 and 6 show the following: "Recess depth," which indicates the radial distance between the part of the outer surface of the can body 10 furthest from the can axis O in recess portion 112A and the part of the outer surface of the can body 10 closest to the can axis O in ground portion 112B; "Ground diameter," which indicates the diameter of the ground portion 113 in ground portion 112B; "Aluminum alloy thickness," which indicates the thickness of the aluminum alloy on the can axis O of the first dome 111A; "Can height," which indicates the can height from the ground portion 112B to the upper end of the can body 12; "Can body outer diameter," which indicates the outer diameter of the can body 12; "Filling specification," which shows the "liquid temperature" and "internal pressure" of the carbonated water filled inside the can body 10; and "Evaluation," which shows the results of the evaluation of deformation at either the dome portion 111 or the annular protrusion 112.

[0038] Figure 5 shows the results of drop tests using can bodies 10 according to examples and comparative examples, in which the aluminum alloy thickness was 0.22 mm, the can height was 155.3 mm, the recess depth was 0.68 mm, the outer diameter of the can body was 57.2 mm, and the contact diameter was varied by 0.5 mm increments from 43.0 mm to 47.5 mm.

[0039] Figure 6 shows the results of drop tests using can bodies 10 according to examples and comparative examples, in which the aluminum alloy thickness was 0.22 mm, the can height was 155.3 mm, the contact diameter was 45.4 mm, the outer diameter of the can body was 57.2 mm, and the recess depth was varied from 0.40 to 0.85 in 0.5 mm increments.

[0040] In the tables shown in Figures 5 and 6, in all drop tests relating to the examples and comparative examples, an aluminum alloy drawn can was used as the can body 10, and the contents of the can body 10 were subjected to drop tests with an internal pressure of 400 kPa and 500 kPa in a standing state before shaking, with the liquid temperature set at 35°C. The results are shown in the "Evaluation" column.

[0041] In the "Evaluation" section, if the can body 12 was tilted at an angle of less than 2° and no inversion of the dome portion 111 was observed when the can body was placed on a horizontal surface and stood upright after the drop test, it was evaluated as "Pass" and indicated with a "○". Similarly, if the can body 12 was tilted at an angle of 2° or more, or if any inversion of the dome portion 111 was observed when the can body was standing upright, it was evaluated as "Fail" and indicated with a "×".

[0042] As shown in the table in Figure 5, when the ground diameter was 43.0 mm (Comparative Example 1-1), both the individual drop test and the case drop test failed for the two types of cans 10 with internal pressures of 400 kPa and 500 kPa. When the ground diameter was 43.5 mm (Comparative Example 1-2), both the individual drop test and the case drop test failed for the can 10 with an internal pressure of 500 kPa. Furthermore, when the ground diameter was 47.5 mm (Comparative Example 1-3), only the case drop test with an internal pressure of 400 kPa showed no deformation in the dome section 111; all other cases resulted in failure.

[0043] On the other hand, when the contact diameter was between 44.0 mm and 47.0 mm (Examples 1-1 to 1-7), both the individual drop test and the case drop test were passed for two types of can bodies 10 with internal pressures of 400 kPa and 500 kPa.

[0044] Furthermore, as shown in the table in Figure 6, when the recess depth was 0.40 mm (Comparative Example 2-1), both the individual drop test and the case drop test failed for the two types of cans 10 with internal pressures of 400 kPa and 500 kPa. When the recess depth was 0.45 mm (Comparative Example 2-2), only the individual can with internal pressure of 400 kPa passed, while the others failed. When the recess depth was 0.85 mm (Comparative Example 2-3), both the individual drop test and the case drop test failed for the two types of cans 10 with internal pressures of 400 kPa and 500 kPa.

[0045] On the other hand, when the recess depth was between 0.50 mm and 0.80 mm (Examples 2-1 to 2-7), both the individual drop test and the case drop test were passed for two types of can bodies 10 with internal pressures of 400 kPa and 500 kPa.

[0046] As described above, according to this embodiment, the shape and dimensions of the can body are optimized, and the bottom of the can 11 is remodeled so that the recess depth is 0.5 mm or more and 0.8 mm or less, and the contact diameter is φ44.0 mm or more and 47.0 mm or less. In this way, the can body 10 can be made to ensure pressure resistance and drop strength while ensuring a predetermined amount of contents to be filled. [Explanation of Symbols]

[0047] 10: Can body, 11: Can bottom, 12: Can cylinder, 20: Reform roll, 111: Dome section, 111A: First dome, 111B: Second dome, 111C: Tapered section, 112: Annular protrusion, 112A: Recess section, 112B: Ground contact section, 112C: Inner circumferential wall section, 113: Ground contact area, 113A: First convex curved surface section, 113B: Second convex curved surface section, 121: Neck section, 121A: Concave curved surface, 121B: Convex curved surface, 121C: Concave curved surface, 123: Flange section

Claims

1. A bottomed cylindrical aluminum alloy can body having a can bottom and a cylindrical can body centered on the can axis, extending from the outer circumference of the can bottom along the can axis, The can bottom has a dome portion provided in the center of the can bottom, and an annular projection that is continuous with the outer edge of the dome portion and protrudes annularly outward from the can body along the can axis, The thickness of the aluminum alloy on the can shaft in the dome portion is 0.18 to 0.26 mm. The aforementioned annular protrusion is, A recess portion is provided continuously with the dome portion and has a curved surface that protrudes radially outward from the can body, The grounding portion that supports the aforementioned can body, Including the inner circumferential wall portion extending from the ground contact portion to the recess portion, The ground contact portion has a first convex curved surface on the side closer to the can axis and a second convex curved surface on the side further from the can axis, with the portion that protrudes most in the downward direction toward the can axis in the ground contact portion being sandwiched between them. The inner circumferential wall portion has an inclined surface, The outer diameter of the can body is within the range of 50 mm to 59 mm in diameter. The height of the can from the ground portion to the upper end of the can body is within the range of 120 mm to 190 mm. In a longitudinal cross-sectional view including the can shaft, The recess depth is 0.5 mm or more and 0.9 mm or less. The grounding diameter is φ44.0 mm or more and 47.0 mm or less. The radius of curvature of the first convex curved surface is 0.4 mm or more and 0.7 mm or less. The radius of curvature of the second convex curved surface is 1.6 mm or more and 2.2 mm or less. A can body in which the angle between the inclined surface on the inner circumferential wall and the can axis is 15° or more and 30° or less. Here, the recess depth is the radial distance between the part of the outer surface of the can body in the recess that is furthest from the can axis and the part of the outer surface of the can body in the grounding portion that is closest to the can axis, and the grounding diameter is the diameter of the part of the grounding portion that protrudes most downward in the direction of the can axis.

2. The radius of curvature of the recess is 0.3 mm or more and 1.2 mm or less. The can body according to claim 1, wherein the distance in the can axis direction from the portion of the contact area that protrudes most in the downward direction in the can axis direction to the portion of the outer surface of the can body in the recess that is furthest from the can axis is 1 mm or more and 4 mm or less.

3. The aforementioned dome section is The can body according to claim 1 or claim 2, comprising a tapered portion having one end continuous with the outer periphery of the dome portion and the other end continuous with the recess portion.

4. The can body according to any one of claims 1 to 3, wherein the dome portion includes a first dome that is recessed inward along the can axis in the central part of the can bottom, and a second dome that is continuously provided radially outward on the outer edge of the first dome, recessed inward on the can body, and having a smaller radius of curvature than the first dome.

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