Can end and method of manufacturing the same

Abstract

The present invention aims to improve the pressure resistance while meeting the requirement of further reducing the thickness of the plate. The can lid of the present invention has a center plate portion, a plate wall portion, a chuck wall arc portion, a chuck wall portion, and a curl portion. When the thickness of the center plate portion is t1 and the thickness of the lower end of the plate wall portion is t2, t2 > t1.

Description

Technical Field

[0001] This invention relates to a can lid and a method for manufacturing the same. Background Technology

[0002] When a metal can filled with beverages is a two-piece can, the contents are sealed by rolling a lid onto the open end of the bottomed cylindrical can body. This type of lid typically uses a pull-ring type with a recessed opening. After the contents are filled into the can body, the lid is rolled onto the open end of the can body, and therefore is usually supplied separately from the can body in a stacked manner to the filling point.

[0003] The can lid has a central plate portion for mounting an opening pull ring, and an annular groove portion around which an inner tool (sealing chuck) for inserting into a sealing machine protrudes from the outer edge. Furthermore, the can lid has a coiled portion on the outer periphery of the annular groove portion for sealing the open end of the can body (see, for example, Patent Document 1 below).

[0004] Furthermore, as part of the structure of this can lid, a plate wall portion is formed as the inner wall portion of the groove in the annular groove portion, a clamping wall arc portion is formed in the portion from the inner wall portion of the groove to the outer wall portion of the groove in the annular groove portion, and a clamping wall portion is formed in the portion from the outer wall portion of the groove to the curled portion.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-112143

[0008] Patent Document 2: Japanese Patent Application Publication No. 3-275443 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] Regarding metal cans, in order to conserve material resources and reduce weight, it is required to make the plate thickness as thin as possible. However, if the plate thickness is reduced, the strength (pressure resistance) when the internal pressure rises will be a problem.

[0011] Regarding the can lid, if the internal pressure rises, it will generate an upward force pressing against the center plate. Therefore, when the internal pressure rises abnormally, buckling may occur, where the annular groove protrudes upwards, causing both the annular groove and the center plate to bulge upwards at an angle. In particular, when the contents are carbonated beverages, buckling is more likely to occur if the internal temperature rises abnormally due to the surrounding environment.

[0012] Regarding the structure of the can lid used to improve pressure resistance, various countermeasures have been studied, as in the prior art shown in Patent Document 1 above. However, as in the aforementioned prior art, these countermeasures only focus on shape design such as providing a first bend and a second bend in the clamping wall portion and specifying the relationship between the curvature radius of the first bend and the curvature radius of the second bend, without rigorously studying the plate thickness.

[0013] This invention was proposed to address this problem. The objective of this invention is to obtain a can lid with high pressure resistance while meeting the requirement of further reducing the thickness of the plate through rigorous research on plate thickness.

[0014] Solution for solving the problem

[0015] To address this issue, the can lid based on the present invention has the following structure.

[0016] A can lid, characterized in that it has a central plate portion, a plate wall portion, a clamping wall arc portion, a clamping wall portion, and a curled portion, wherein when the plate thickness of the central plate portion is set as t1 and the plate thickness of the lower end of the plate wall portion is set as t2, t2 > t1.

[0017] The effects of the invention

[0018] Can lids with this feature can achieve high pressure resistance while meeting the requirement of further reducing plate thickness, thereby improving the pressure resistance of the can lid. Attached Figure Description

[0019] Figure 1 This is an explanatory diagram showing a partial cross-section of the can lid.

[0020] Figure 2 This is an explanatory diagram showing the manufacturing process of the can lid.

[0021] Figure 3 This is an explanatory diagram showing the molded body in the manufacturing process. Figure 3 (a) is a molded body formed from process S1 to process S3. Figure 3 (b) Figure 3 (c) is the molded body formed by process S4. Figure 3 (d) is the final can lid.

[0022] Figure 4 This is an explanatory diagram showing the blank stamping process. Figure 4 (a) is before stamping. Figure 4 (b) is after stamping).

[0023] Figure 5 This is an explanatory diagram of the deep drawing process on the outer perimeter. Figure 5 (a) is during the deep stretching process. Figure 5 (b) is the completion of deep drawing).

[0024] Figure 6 This is an explanatory diagram of the sheet metal deep drawing process. Figure 6 (a) is at the beginning of deep drawing. Figure 6 (b) is when the deep drawing is completed.

[0025] Figure 7 This is an explanatory diagram of the plate pressing process. Figure 7 (a) is when the downward pressure begins. Figure 7 (b) is during the downward pressure.

[0026] Figure 8 This is an explanatory diagram of the plate pressing process. Figure 8 (a) indicates that the downward pressure is complete. Figure 8 (b) is to remove the molded product.

[0027] Figure 9 This is an explanatory diagram illustrating an example of applying a thinning process during the deep drawing process of a sheet metal part.

[0028] Figure 10 This is an explanatory diagram illustrating an example of another shape representing an embodiment of the present invention.

[0029] Figure 11 This is a diagram showing the measurement location of the plate thickness in the middle part of the clamping wall. Figure 11 (a) indicates Figure 10 A diagram of the measurement location in another embodiment. Figure 11 (b) is a diagram showing the measurement locations of the implementation method. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same symbols in different figures indicate parts with the same function, and repeated descriptions in each figure are omitted as appropriate.

[0031] like Figure 1 As shown, the can lid 1 according to the embodiment of the present invention has a central plate portion 1A, a plate wall portion 1B, a clamping wall arc portion 1C, a clamping wall portion 1D, and a curled portion 1E. The central plate portion 1A is a generally flat portion in the center of the can lid 1, and when it is a retaining pull ring type, it is provided with a grooved or opening pull ring.

[0032] A curved portion r1 is formed on the outer edge of the central plate portion 1A, and the portion that descends in a straight line from the end of the curved portion r1 becomes the plate wall portion 1B. Furthermore, the curved portion r2 formed below the plate wall portion 1B, that is, the portion including the bottom of the annular groove portion Cs formed on the outer periphery of the central plate portion 1A, becomes the clamping wall arc portion 1C. And the straight or partially curved portion extending upward from the upper outer end of the clamping wall arc portion 1C, that is, the portion extending further from the outer wall of the aforementioned annular groove portion Cs to before the curvature of the curled portion 1E, becomes the clamping wall portion 1D.

[0033] Furthermore, in the embodiments of the present invention, when the thickness of the central plate portion 1A is set to t1 and the thickness of the lower end of the plate wall portion 1B is set to t2, t2 > t1. The thickness t1 of the central plate portion 1A is close to the original thickness of the material being processed before the can lid 1 is formed.

[0034] The lower end of the plate wall portion 1B is the boundary portion with the curved portion r2 of the clamping wall arc portion 1C. In the can lid 1, by employing a new method in the forming process of the clamping wall arc portion 1C, the plate thickness t2 at the lower end of the plate wall portion 1B is set to be thicker than the plate thickness t1, resulting in a can lid 1 with higher pressure resistance than previous shape designs. By setting the plate thickness t2 to be 1.01 times thicker than the plate thickness t1 (t2 > 1.01 × t1), a can lid 1 with even higher pressure resistance can be obtained.

[0035] Furthermore, regarding the can lid 1, when the plate thickness of the clamping wall arc portion 1C is set to t3, by setting the plate thickness t3 to be thicker than the plate thickness t1, preferably to be thicker than 1.01 times the plate thickness t1 (t3 > 1.01 × t1), a can lid 1 with high pressure resistance can be obtained.

[0036] Furthermore, regarding the can lid 1, when the thickness of the middle portion of the clamping wall 1D is... Figure 1 When the plate thickness at the position where the actual height of the can lid is divided into two parts is set to t4, t1 > t4. Accordingly, by thinning the middle part of the clamping wall 1D, which has less impact on the pressure resistance, the can lid 1 can be made lighter while maintaining the specified pressure resistance.

[0037] The aforementioned can lid 1, by locally thickening the plate thickness of the annular groove portion Cs formed on the outer periphery of the central plate portion 1A, the plate wall portion 1B, and the clamping wall arc portion 1C, can further improve the pressure resistance by making the conventional shape design of the annular groove portion Cs and the portion from there to the curled portion 1E more reasonable.

[0038] The aforementioned can lid 1 can have a plate thickness of the annular groove portion Cs formed on the outer periphery of the central plate portion 1A, the plate wall portion 1B, and the clamping wall arc portion 1C that is thicker than the original plate thickness of the material being processed (the plate thickness t1 of the central plate portion 1A). Therefore, the original plate thickness of the material being processed can be made as thin as possible, thereby effectively saving material resources and reducing weight.

[0039] The manufacturing method of can lid 1 is described below. The manufacturing process of can lid 1 is as follows: Figure 2 The diagram shows a blank stamping process S1, an outer peripheral drawing process S2, a plate drawing process S3, and a plate pressing process S4.

[0040] In these processes, molding is achieved through processes S1 to S3. Figure 3 (a) The molded body M1 shown in the figure is processed in step S4, where the lower pressure plate portion p (the part to be processed in the center plate portion 1A) of the molded body M1 is processed to form the body. Figure 3 (b) Figure 3 (c) The molded bodies M2 and M3 shown in the figure are finally obtained Figure 3 (d) shows the can lid 1.

[0041] Each process is described in detail. It is used as a processing tool in each process. Figures 4-8 The upper tool U and the lower tool L are shown. The upper tool U has an inner tool U1 and an outer tool U2, and the lower tool L has a fixed inner tool L1, a movable inner tool L2, a movable outer tool L3, and a fixed outer tool L4.

[0042] In the blank stamping process S1, such as Figure 4 As shown in (a), the workpiece M is inserted between the upper tool U and the lower tool L, as follows: Figure 4 As shown in (b), the upper tool U descends and the disc-shaped molded body M01 is formed by the stamping of the machining surface a based on the outer tool U2 and the machining surface b of the fixed outer tool L4.

[0043] In the outer peripheral drawing process S2, the upper tool U is further lowered, such as... Figure 5 As shown in (a), the lower surface c of the outer tool U2 and the upper surface d of the movable outer tool L3 clamp the outer periphery of the molded body M02, and deep drawing is performed on the outer periphery of the molded body M02 based on the machining surface e of the movable inner tool L2. The upper tool U is further lowered, as... Figure 5 As shown in (b), the lower surface c of the outer tool U2 presses down on the movable outer tool L3, thereby performing deep drawing processing on the molded body M03 through the machining surface f of the outer tool U2 and the machining surface g of the movable inner tool L2.

[0044] In the plate drawing process S3, such as Figure 6As shown in (a), the upper tool U further descends, and the machining surface h of the outer tool U2 and the machining surface e of the movable inner tool L2 clamp the outer periphery of the formed body M04. The plate portion p of the formed body M04 abuts against the upper surface of the fixed inner tool L1, thus performing a deep drawing process on the plate portion p. Furthermore, in this state, as... Figure 6 As shown in (b), the upper tool U descends further, clamping the outer periphery of the molded body M05 while pressing down the movable inner tool L2. At the same time, the lower surface of the inner tool U1 and the upper surface of the fixed inner tool L1 clamp the plate part p, thereby performing deep drawing processing on the plate part p.

[0045] Then, in the plate pressing process S4, as follows Figure 7 As shown in (a), the outer tool U2 is pressed down by the movable inner tool L2 while the outer periphery of the molded body M06 is clamped between the machining surface e and the machining surface h. Figure 7 As shown in (b), the plate portion p of the molded body M06 is pressed down relative to the outer peripheral portion, thereby forming the molded body M07.

[0046] Then, as Figure 8 As shown in (a), if the aforementioned relative downward pressing of the plate portion p is further performed, the machined portion processed in the clamping wall arc portion 1C between the plate portion p and the outer peripheral portion of the molded body M08 is pressed into the groove portion j provided between the fixed inner tool U2 and the movable inner tool L2. Thus, the plate wall portion 1B and the clamping wall arc portion 1C are formed. Furthermore, by the relative downward pressing of the plate portion p, the curled portion 1E is formed in the outer peripheral portion clamped between the machined surface e and the machined surface h. And, the center plate portion 1A is formed in the plate portion p clamped between the lower surface of the inner tool U1 and the upper surface of the fixed inner tool L1. Then, as... Figure 8 As shown in (b), release the upper tool U and the lower tool L, and remove the molded part of the can lid 1.

[0047] Afterwards, although not shown in the figure, the outermost periphery of the molded part of the can lid 1 is rolled into a shape suitable for sealing by a known method, and a sealant is applied to its inner surface. Depending on the application, the plate part is riveted, scored, and the pull ring is closed to complete the can lid.

[0048] According to the aforementioned manufacturing process, by pressing down the plate portion p, which is the part to be processed in the center plate portion 1A, the part to be processed in the clamping wall arc portion 1C is pressed into the groove portion j, and the plate wall portion 1B and the clamping wall arc portion 1C are formed. Therefore, the processing surface of the processing tool does not directly contact the plate wall portion 1B and the clamping wall arc portion 1C, and the forming process can be performed. Furthermore, by pressing down the plate portion p, compressive stress in a direction orthogonal to the plate thickness direction is applied to the part to be processed in the plate wall portion 1B and the clamping wall arc portion 1C, thus plastic deformation such as an increase in plate thickness occurs.

[0049] Furthermore, as a processing tool, such as Figure 9 The mold shown uses a die with a thinning protrusion k1 provided on the fixed inner tool L10. Furthermore, by thinning the molded body between the inner machining surface k2 of the outer tool U2 of the upper tool U and the thinning protrusion k1, thinning processing can be applied to the middle portion of the clamping wall 1D in the aforementioned plate drawing process S3. Thus, by applying thinning processing to a portion of the clamping wall 1D (especially the central portion), the thickness of that portion of the clamping wall 1D can be reduced. Therefore, while meeting the requirements of material conservation and lightweighting, the pressure resistance of the can lid 1 can be effectively improved.

[0050] Furthermore, the aforementioned manufacturing process involves stamping the blank into a molded can lid 1 using a single stroke within an upper and lower die. However, it is also possible to perform this series of processes in multiple stages using a separate die. In particular, the compressive stress acting on the plate portion p during the plate pressing process S4, in a direction orthogonal to the plate thickness direction, contributes to this process. Figure 8 The state described in (a), that is, the state in which the workpiece is pressed into the bottom of the groove j, is the maximum. Therefore, the pressing is divided into multiple stages, and the plate is pressed down each time using a mold with the bottom of the groove, thereby enabling control to further expand the range of increasing plate thickness.

[0051] [Example]

[0052] As the material being processed, M is used to coat an Al alloy (A5182-H19) with a thickness of 0.26 mm at a concentration of 15 mg / dm³. 2 External surface coating and 100mg / dm 2 The inner surface coating material is coated in roll form. The can lid 1 is formed in the aforementioned manufacturing process, and examples of measuring the thickness of each part are shown in Table 1 below. Additionally, t5 is the thickness of the upper end of the wall portion 1B. Here, in Example 1, the outer diameter φh of the fixed inner tool L1 is 51.58 mm; in Example 2, it is φh = 52.18 mm; and in Example 3, it is φh = 51.58 mm. Thinning processing is performed at approximately 7% in the middle portion of the clamping wall portion 1D, otherwise, it is formed in the same manner as in Example 1.

[0053] [Table 1]

[0054] Thick sections t1 t2 t3 t4 t5 Pressure resistance (MPa) Example 1 0.260 0.290 0.271 0.275 0.280 0.752 Example 2 0.260 0.302 0.279 0.285 0.291 0.766 Example 3 0.260 0.307 0.282 0.256 0.301 0.777 Comparative example 0.260 0.242 - 0.258 0.240 0.691

[0055] As shown in Table 1, in Example 1, the plate thickness t2 is 1.01 times thicker than the plate thickness t1, and in Example 2, both plate thicknesses t2 and t3 are 1.01 times thicker than the plate thickness t1. Furthermore, in Example 3, the plate thickness t4 is thinned through a thinning process, thereby allowing for the corresponding filling of more metal portions of the processed parts in the plate wall portion 1B and the clamping wall arc portion 1C. As a result, the plate thicknesses t2 and t3 can be further increased by the compressive stress in a direction orthogonal to the plate thickness direction based on the downward pressure of the plate portion p. This adjustment of plate thickness improves the compressive strength compared to the comparative example performed using the conventional method in Patent Document 2.

[0056] As explained above, the can lid 1 according to the embodiments of the present invention can achieve a can lid 1 with high pressure resistance while meeting the requirement of further thinning the plate thickness, thereby improving the pressure resistance of the can lid 1. The can lid 1, rolled and sealed to the can body, can achieve a reduction in the weight of the metal can relative to the weight of the contents while ensuring high pressure resistance.

[0057] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments, and design changes that do not depart from the spirit and scope of the present invention are also included in the present invention. Furthermore, as long as there are no particular contradictions or problems in their purpose and structure, the above embodiments can be combined with each other's techniques. For example, the embodiment shown in Patent Document 1... Figure 10 The present invention can also be incorporated into can lid 1 with such a cross-sectional shape.

[0058] Figure 11 This is a diagram showing the measurement location for the thickness of the plate in the middle section of the clamping wall. Figure 11 (a) indicates Figure 10 A diagram of the measurement location in another embodiment, and, Figure 11 (b) is a diagram showing the measurement locations of the implementation method.

[0059] exist Figure 11 (a) and Figure 11 In any of the cases in (b), when the thickness of the plate at the middle part of the clamping wall 1D of the can lid 1, i.e., the thickness of the plate at the position where the actual height of the can lid is divided into two parts, is set to t4, t1 > t4. In another embodiment, by thinning the middle part of the clamping wall 1D, which has less impact on the pressure resistance, the can lid 1 can be made lighter while maintaining the specified pressure resistance.

[0060] in addition, Figure 11 (a) Another implementation method and Figure 11 (b) The implementation methods are respectively shown Figure 10 Part of the can lid 1 and Figure 1A portion of the can lid 1 is rolled up to the can body in a partial cross-section. Before rolling up... Figure 10 and Figure 1 After the roll Figure 11 Comparing the various states, no change in the actual height before and after the roll-sealed can lid 1 was found. Therefore... Figure 11 (a) Another implementation method and Figure 11 (b) In another embodiment, the plate thickness t4 is at approximately the same position.

[0061] Explanation of reference numerals in the attached figures

[0062] 1-Can lid, 1A-Central plate, 1B-Plate wall, 1C-Clamping wall arc, 1D-Clamping wall, 1E-Curled part, U-Upper tool, L-Lower tool, p-Plate.

Claims

1. A can lid comprising a central plate portion, a plate wall portion, a locking wall arc portion, a locking wall portion, and a rolled portion, characterized in that, When the thickness of the central plate is set to t1 and the thickness of the lower end of the plate wall is set to t2, By making the thickness of the plate wall portion greater than the original thickness of the material being processed, t2 > t1 is achieved.

2. The can lid according to claim 1, characterized in that, When the thickness of the central plate is set to t1 and the thickness of the lower end of the plate wall is set to t2, t2 > 1.01 × t1.

3. The can lid according to claim 1, characterized in that, When the plate thickness of the arc portion of the clamping wall is set to t3... t3 > 1.01 × t1.

4. The can lid according to claim 1, characterized in that, When the thickness of the middle part of the clamping wall is set to t4. t1 > t4.

5. A canned food product using the lid as described in claim 1.

6. A method for manufacturing a can lid, comprising the method for manufacturing a can lid as described in claim 1, characterized in that, The clamping wall arc portion is formed by pressing the processed portion of the central plate relative to the ground.

7. The method for manufacturing a can lid according to claim 6, characterized in that, A portion of the clamping wall is subjected to a thinning process.

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