An easy-open can lid basic lid and an easy-open can lid

Abstract

The present invention provides a basic lid of an easy-open can and an easy-open can lid, which relates to the technical field of packaging containers. The cross-section of the basic lid of the easy-open can lid, from the periphery to the center, is successively a double-seaming area, a transition area, a concave section, an arc wall section, and a center panel. The concave section is successively a first arc section, a first straight section, and a second arc section from the periphery to the center. The first arc section is tangent to the transition area, the first arc section is tangent to the first straight section, and the first straight section is tangent to the second arc section. The radius of the first arc section is set as a, where 0.08 mm ≤ a ≤ 0.2 mm; the radius of the second arc section is set as b, where 0.15 mm ≤ b ≤ 0.4 mm; the arc wall section is successively a second straight section and a third arc section that are tangent from the periphery to the center. The second straight section is tangent to the second arc section, and the third arc section is tangent to the center panel. The radius of the third arc section is set as c, where 1.5 mm ≤ c ≤ 4 mm. The basic lid of the present invention has good yield stress consistency and can effectively reduce the breakage rate under positive pressure.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging containers, and relates to a basic lid of an easy-open can lid and an easy-open can lid. Background Art

[0002] Easy-open cans, such as two-piece cans and three-piece cans, have become packaging containers that can be seen everywhere in people's daily lives. The inside of an easy-open can usually contains a liquid with a certain pressure, such as beer, beverages, etc. As the weather gets warmer and the can shakes during transportation, the pressure inside the can will increase. As the thickness of the easy-open can becomes thinner and thinner, for example, the thickness of the can lid is as low as 0.208 mm, higher requirements are put forward for the pressure resistance of the can lid to achieve lower pressure-induced breakage and safety. For example, under the action of the pressure inside the can, when the internal pressure exceeds the yield strength of the material, the can lid is prone to bulge and deform, and even break. In addition to replacing the original stainless steel material with a higher-strength and lower-density aluminum alloy material, multiple prior arts have also publicly reported improvements to the can lid structure to achieve higher compressive resistance. For example, Chinese invention patent CN108438434A discloses a pressure-resistant basic lid, which adds a sixth arc section R6 and a second straight section L2 to the countersunk section, designs the reasonable sizes of the fifth arc section R5 and the sixth arc section R6, and the positional relationship between the centers of the fourth arc section R4 and the fifth arc section R5 and other technical features to reduce the probability of rupture during pressure-resistant failure to 0.05% - 2.5%.

[0003] The inventor believes that the existing structure of the easy-open can lid can be further optimized. Summary of the Invention

[0004] Since the thickness of the easy-open can lid has been made very thin and cannot be further reduced. Therefore, it is necessary to further design and optimize the structure of the can lid. Through a large amount of research, analysis and testing, the inventor found that maintaining the consistency of the yield stress of the can lid can improve the pressure resistance of the can lid and reduce the breakage rate when the pressure increases. Based on this, the present invention provides a basic lid of an easy-open can lid and an easy-open can lid.

[0005] The technical solution of the present invention is as follows:

[0006] A basic lid of an easy-open can lid, the cross-section of the basic lid from the periphery to the center is successively a double-seam area, a transition area, an inner concave section, an arc wall section and a center panel. The inner concave section is successively a first arc section, a first straight section and a second arc section from the periphery to the center. The first arc section is tangent to the transition area, the first arc section is tangent to the first straight section, and the first straight section is tangent to the second arc section;

[0007] The radius of the first arc section is set as a, 0.08 mm ≤ a ≤ 0.2 mm;

[0008] The radius of the second arc segment is set as b, where 0.15 mm ≤ b ≤ 0.4 mm;

[0009] The arc wall segment consists of a second straight segment and a third arc segment that are tangent in sequence from the periphery to the center. The second straight segment is tangent to the second arc segment, and the third arc segment is tangent to the central panel;

[0010] The radius of the third arc segment is set as c, where 1.5 mm ≤ c ≤ 4 mm.

[0011] Preferably, the transition region includes a third straight segment that is tangent to the first arc segment.

[0012] Preferably, the angle A1 between the first straight segment and the horizontal direction is 2 - 15°.

[0013] More preferably, the angle A1 is 3 - 10°.

[0014] Preferably, the value of a satisfies: 0.1 mm ≤ a ≤ 0.17 mm.

[0015] Preferably, the value of b satisfies: 0.18 mm ≤ b ≤ 0.35 mm.

[0016] Preferably, the angle A2 between the second straight segment and the vertical direction is 10 - 35°.

[0017] More preferably, the angle A2 is 13 - 28°.

[0018] Preferably, the center of the third arc segment is not lower than the lowest point of the concave part of the concave segment in the horizontal direction.

[0019] An easy - open can lid includes the easy - open can lid basic lid described in any one of the above - mentioned embodiments.

[0020] The beneficial effects of the present invention are as follows: Through the analysis of the stress distribution of the lid under internal positive pressure and the common compression - rupture modes of the lid, the present invention proposes a lid structure that can improve the consistency of yield stress. By setting two arc segments with different arc radii on the concave segment and an arc segment with a longer arc radius on the arc wall segment, the yield stress of different parts of the basic lid can be made more consistent, which is more beneficial for resisting the stress action of internal positive pressure, reducing the breakage rate under high pressure, and also having a lower non - broken rate of bulging. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a partial cross - sectional view of the basic lid of Example 1.

[0022] Figure 2 It is an enlarged view of the curved box part in Example 1.

[0023] Figure 3 Partial schematic view of the cross-section of the basic cover of Example 1 Specific implementation manners

[0024] The technical solutions of the present invention will be further described and illustrated through specific implementation manners below.

[0025] The term "horizontal direction" in the present invention is explained as follows: the direction along the cross-section of the basic cover and perpendicular to the central axis of the can lid.

[0026] The term "vertical direction" in the present invention is explained as follows: the direction parallel to the central axis of the can lid. Upward, the direction in which the lid surface is away from the bottom of the can.

[0027] In order to improve the compressive resistance of the easy-open can lid, from the dimension of improving the uniformity of the yield stress of each part of the lid, on the one hand, the present invention provides a basic cover for an easy-open can lid. The cross-section of the basic cover from the periphery to the center is successively a double-seaming area (1), a transition area (2), a concave section (3), an arc wall section (4), and a central panel (5). The basic cover of the present invention is improved on the basis of the basic cover in the prior art. The structures of the double-seaming area (1), the transition area (2), and the central panel (5) are not particularly limited, and reference can be made to the descriptions in prior arts such as CN108438434A, CN106672390A, CN105408216A, etc.

[0028] For the concave section (3), the present invention is designed as follows: the concave section (3) successively includes a first arc segment (R1), a first straight segment (L1), and a second arc segment (R2) from the periphery to the center. The first arc segment (R1) is tangent to the transition area (2), the first arc segment (R1) is tangent to the first straight segment (L1), and the first straight segment (L1) is tangent to the second arc segment (R2);

[0029] The radius of the first arc segment (R1) is set as a, where 0.08 mm ≤ a ≤ 0.2 mm;

[0030] The radius of the second arc segment (R2) is set as b, where 0.15 mm ≤ b ≤ 0.4 mm;

[0031] For the structure of the concave section (3) described above, it is composed of a first arc section (R1) and a second arc section (R2), and is connected by a first straight section (L1) in the middle. The inventor found that the breakage of the easy-open can lid under positive pressure mainly occurs in the transition section and the arc wall section, especially in the transition section, indicating that the yield stress of the transition section is relatively low among all parts of the lid. In the present invention, through the structural design of the concave section (3) above, while increasing the yield stress of the transition area (2), the yield stress of the concave section (3) will not be reduced, maintaining the consistency of the yield stress of all parts of the basic lid, and can effectively reduce the high-pressure breakage rate of the lid. In the present invention, further, the radius of the first arc section (R1) is smaller than the radius of the second arc section (R2). For example, the value of a can be any value among 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.20 mm, etc. or any value between them, without any particular limitation. For example, the value of b can be any value among 0.15 mm, 0.17 mm, 0.20 mm, 0.21 mm, 0.22 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.34 mm, 0.35 mm, 0.36 mm, 0.38 mm, 0.40 mm, etc. or any value between them, without any particular limitation.

[0032] For the arc wall section (4), the design of the present invention is as follows: The arc wall section (4) is successively a tangent second straight section (L2) and a third arc section (R3) from the periphery to the center. The second straight section (L2) is tangent to the second arc section (R2), and the third arc section (R3) is tangent to the central panel;

[0033] The radius of the third arc section (R3) is set as c, and 1.5 mm ≤ c ≤ 4 mm. For example, the value of c can be any value among 1.5 mm, 1.7 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.2 mm, 3.3 mm, 3.5 mm, 3.6 mm, 3.8 mm, 4.0 mm, etc. or any value between them, without any particular limitation. Further, the value of c can be 2 - 3 mm.

[0034] The structural designs of the above concave section (3) and arc wall section (4) form a good integration with the transition area (2). While increasing the yield stress of the transition area (2), the yield stress of the arc wall section (4) will not be reduced, further effectively reducing the high-pressure breakage rate of the lid.

[0035] Further, in the present invention, the transition region (2) includes a third straight segment (L3), and the third straight segment (L3) is tangent to the first arc segment (R1). By adopting the above technical solution, the connection between the transition region (2) and the concave segment (3) can be made more coherent and smoother, avoiding a reduction in the yield stress.

[0036] Further, in the present invention, the angle A1 between the first straight segment (L1) and the horizontal direction is 2 - 15°. The first straight segment (L1) forms a certain angle A1 with the horizontal direction, that is, the second arc segment (R2) deviates upward relative to the first arc segment (R1). For example, the angle A1 can be any value among 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15° or any value between them, without any particular limitation. Further, the angle A1 is 3 - 10°.

[0037] Further, in the present invention, the value of a satisfies: 0.1 mm ≤ a ≤ 0.17 mm. For example, the value of a can be any value among 0.10 mm, 0.11 mm, 0.12 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm or any value between them, without any particular limitation.

[0038] Further, in the present invention, the value of b satisfies: 0.18 mm ≤ b ≤ 0.35 mm. For example, the value of b can be any value among 0.18 mm, 0.20 mm, 0.21 mm, 0.22 mm, 0.24 mm, 0.25 mm, 0.26 mm, 0.27 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.34 mm, 0.35 mm or any value between them, without any particular limitation.

[0039] Further, in the present invention, the angle A2 between the second straight segment (L2) and the vertical direction is 10 - 35°. For example, the angle A2 can be any value among 10°, 12°, 13°, 15°, 16°, 18°, 19°, 20°, 22°, 23°, 24°, 25°, 26°, 28°, 29°, 30°, 32°, 33°, 34°, 35° or any value between them, without any particular limitation. Further, the angle A2 is 13 - 28°.

[0040] Further, in the present invention, the center of the third arc segment (R3) is not lower than the lowest point of the concave part of the concave segment (3) in the horizontal direction.

[0041] On the other hand, the present invention also provides an easy - open can lid, including the easy - open can lid basic lid described in any of the above embodiments. The easy - open can of the present invention has a higher yield stress and can reduce the breakage rate under positive pressure.

[0042] The technical solutions of the present invention will be further described and illustrated according to the following embodiments.

[0043] Embodiment 1

[0044] Referring to the attached Figure 1 , the cross-section of the basic cover of the easy-open can from the periphery to the center is successively a double-seaming area 1, a transition area 2, a concave section 3, an arc wall section 4, and a center panel 5. The structures of the double-seaming area 1, the transition area 2, and the center panel 5 can refer to the description in the prior art CN106672390A. The double-seaming area 1, the transition area 2, and the center panel 5 in the present invention respectively correspond to the can seaming area, the countersunk section, and the center cover surface in the prior art CN106672390A. That is, in the basic cover of the present invention, the double-seaming area successively includes a fourth arc segment R4 (corresponding to the first arc segment in CN106672390A, not shown in the drawings of this embodiment), a fifth arc segment R5 (corresponding to the second arc segment in CN106672390A, not shown in the drawings of this embodiment), and a sixth arc segment R6 (corresponding to the third arc segment in CN106672390A, not shown in the drawings of this embodiment) from the periphery to the center. R5 is respectively tangent to R4 and R6; the transition area is successively connected and tangent by a fourth straight segment L4 (corresponding to the first straight segment in CN106672390A, not shown in the drawings of this embodiment), a seventh arc segment R7 (corresponding to the fourth arc segment in CN106672390A, not shown in the drawings of this embodiment), and an eighth arc segment R8 (corresponding to the fifth arc segment in CN106672390A, not shown in the drawings of this embodiment). The other end of L4 is connected and tangent to R6. The radius of R8 is 3.5 mm, and the radius of R7 is 1.5 mm. The external tangent of L4 and R6 forms an angle of 12° with the vertical direction.

[0045] The concave section (3) successively includes a first arc segment R1, a first straight segment L1, and a second arc segment R2 from the periphery to the center. The first arc segment R1 is tangent to the transition area 2, the first arc segment R1 is tangent to the first straight segment L1, and the first straight segment L1 is tangent to the second arc segment R2; the radius a of the first arc segment R1 is 0.12 mm; the radius b of the second arc segment R2 is 0.23 mm. The transition area 2 includes a third straight segment L3. One end of the third straight segment L3 is tangent to the first arc segment R1, and the other end of the third straight segment L3 is tangent to the eighth arc segment R8.

[0046] The arc wall section 4 successively includes a second straight segment L2 and a third arc segment R3 that are tangent from the periphery to the center. The second straight segment L2 is tangent to the second arc segment R2, and the third arc segment R3 is tangent to the center panel; the radius c of the third arc segment R3 is 2 mm. The center of the third arc segment R3 is not lower than the lowest point of the concave part of the concave section 3 in the horizontal direction.

[0047] Refer to the appendix Figure 2 For the first straight line segment L1, the included angle A1 with the horizontal direction is 6°, and for the second straight line segment L2, the included angle A2 with the vertical direction is 23°.

[0048] The material of the can lid is 5182 aluminum alloy with a thickness of 0.208 mm, and it is made into a two-piece can. The can body and the can bottom are made of 3004 aluminum alloy with a thickness of 0.22 mm. The structures of the can lids are respectively the structure of Embodiment 1 in the prior art CN106672390A (denoted as the prior art) and the structural design of the above-mentioned Embodiment 1 (denoted as the present invention), where the structures of the double-seam area, the transition area, and the central panel are the same. The above-mentioned can lids are made into two-piece cans, and the two-piece cans are placed in the Easy Open Lid Pressure Resistance Tester CanNeed-AEBT-1000 for testing. Testing conditions: 25°C, 55% humidity, pressurized to 0.7 MPa. The breakage rate and the bulging but unbroken rate of 1000 two-piece cans are counted respectively. The breakage rate of the can lids of the prior art is 75.4%, and the remaining can lids are bulging but unbroken; the breakage rate of the can lids of the present invention is 1.47%, and the bulging but unbroken rate of the can lids is 20.1%. The above data show that the basic lid of this embodiment has a high yield stress.

[0049] Embodiment 2

[0050] Refer to the appendix Figure 3 In this embodiment, the basic lid structure is basically the same as that of Embodiment 1, the difference being that the radius c of the third arc segment (R3) in the appendix Figure 3 is 2.8 mm. According to the above test scheme for the breakage rate, in this embodiment, the breakage rate of the can lids of the two-piece cans is 1.82%, and the bulging but unbroken rate of the can lids is 25.8%, indicating that the basic lid of this embodiment has a high yield stress.

[0051] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments are only preferred embodiments of the present invention, and the scope of implementation of the present invention cannot be defined thereby. That is, equivalent changes and modifications made according to the scope of the present invention patent and the content of the specification should still fall within the scope covered by the present invention. The scope of protection required by the present invention is defined by the appended claims and their equivalents.

Claims

1. A basic cover for an easy-open can lid, wherein the cross section of the basic cover, from the periphery to the center, comprises a crimping area (1), a transition area (2), an inner concave section (3), an arc wall section (4) and a central panel (5), characterized in that: The concave section (3) is composed of a first arc segment (R1), a first straight segment (L1) and a second arc segment (R2) from the periphery to the center, the first arc segment (R1) and the transition zone (2) are tangent to each other, the first arc segment (R1) and the first straight segment (L1) are tangent to each other, and the first straight segment (L1) and the second arc segment (R2) are tangent to each other; The radius of the first arc segment (R1) is set to a, a=0.12 mm; The radius of the second arc segment (R2) is set to b, b=0.23 mm; The arc wall segment (4) comprises, from the periphery to the center, a second straight line segment (L2) and a third arc segment (R3) which are tangent to each other, the second straight line segment (L2) being tangent to the second arc segment (R2), and the third arc segment (R3) being tangent to the center panel (5); The radius of the third arc segment (R3) is set to c, c=2 mm.

2. The basic cover of the easy-open can lid according to claim 1, characterized in that: The transition zone (2) comprises a third straight line segment (L3), and the third straight line segment (L3) is tangent to the first circular arc segment (R1).

3. The basic cover of the easy-open can lid according to claim 1, characterized in that: The angle A1 between the first straight line segment (L1) and the horizontal direction is 2-15°.

4. The basic cover of the easy-open can lid according to claim 3, characterized in that: The angle A1 is 3-10°.

5. The basic cover of the easy-open can lid according to claim 1, characterized in that: An included angle A2 between the second straight line segment (L2) and the vertical direction is 10-35°.

6. The basic cover of the easy-open can cover according to claim 5, characterized in that: The angle A2 is 13-28°.

7. The basic cover of the easy-open can cover according to claim 1, characterized in that: The center of the third arc segment (R3) is not lower than the lowest point of the concave portion of the concave segment (3) in the horizontal direction.

8. An easy-open can lid, characterized in that: The invention comprises the basic cover of the easy-open can cover according to any one of claims 1 to 7.

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