JP3784550B2 - Can lid for positive internal pressure can - Google Patents

Description

表１からわかるように、比較例の缶蓋ａ，ｂ，...，ｉでは、そのそれぞれが缶蓋の耐圧強度とシャッフル値との少なくとも一方が所望の値を満たすことができないことがわかる。また、内面被膜の欠陥が不可と判定されている缶蓋も存在することがわかる。一方、本発明の実施例である缶蓋Ａ，Ｂでは、どちらも缶蓋の耐圧強度とシャッフル値との所望の値を満たしているとともに、内面被膜の欠陥が可と判定されていることがわかる。
【００３８】
【実施例２】
また一方、本発明の缶蓋１として４種類の缶蓋を用意する。それらの缶蓋Ｃ，Ｄ，Ｅ，Ｆは５１８２−Ｈ３８アルミニウム合金からなり、板厚が０．２６ｍｍであって、缶体内面となる表面に塩化ビニルオルガノゾル塗料が１４０ｍｇ／ｄｍ２塗布、焼付け硬化されている。また、缶蓋Ｃ，Ｄ，Ｅ，Ｆはフランジ・カール部の外径が６４．６５ｍｍ（蓋呼称２０６）であって、強化環状溝３の底壁３ｂの上面からフランジ・カール部７の上端面までの長さｈ２が６．９０ｍｍ、強化環状溝の底壁３ｂと外側壁３ｃとを連結する部分の曲率半径ｒが０．３５ｍｍ、ショルダー壁６の曲率半径が１．８０ｍｍ、パネルバイトｈ３が２．３ｍｍ、フランジ・カール部７の上端と下端との長さＴが２．２８ｍｍとなるように形成されている。また、缶蓋Ｃは曲面連結壁４の曲率半径Ｒが７．００ｍｍ、角度θ１が６．５°、角度θ２が１３．５°、長さｈ１が１．８ｍｍであり、曲面連結壁４の最大突出長さの板厚に対する割合が４６．５％になっている。また、缶蓋Ｄは曲面連結壁４の曲率半径Ｒが３．５０ｍｍ、角度θ１が７．５°、角度θ２が１３．５°、長さｈ１が２．２ｍｍであり、曲面連結壁４の最大突出長さの板厚に対する割合が４５．４％になっている。さらに、缶蓋Ｅは曲面連結壁４の曲率半径Ｒが０．６６ｍｍ、角度θ１が８．５°、角度θ２が１３．０°、長さｈ１が２．５ｍｍであり、曲面連結壁４の最大突出長さの板厚に対する割合が３７．３％になっている。また、缶蓋Ｆは曲面連結壁４の曲率半径Ｒが７．００ｍｍ、角度θ１が５．０°、角度θ２が１３．５°、長さｈ１が１．３ｍｍであり、曲面連結壁４の最大突出長さの板厚に対する割合が５０．０％になっている。
【００３９】
また、比較例の缶蓋として、９種類の缶蓋を用意する。それらの缶蓋ｊ，ｋ，...，ｒは、特に記述しない限り本発明の缶蓋１である缶蓋Ｃと同様の形状を有するものである。缶蓋ｊは、チャック壁の傾斜角度θ２を１３．５°とし、強化環状溝の外側壁をパネル部の板厚方向に延出するように形成されている。また、缶蓋ｋは、チャック壁の傾斜角度θ２を１１．２°とし、曲面連結壁の突出長さを０として形成されている。さらに、缶蓋ｌは、曲面連結壁の曲率半径Ｒを１０．００ｍｍとして形成されている。そして、缶蓋ｍと缶蓋ｎは角度θ１、角度θ２を変動させることにより、曲面連結壁の突出長さを本発明の缶蓋１における曲面連結壁の突出長さの範囲から除外させて形成されている。
【００４０】
また、缶蓋ｏは、チャック壁の角度θ２を９．０°とし、θ１がθ２よりも大きくなるように、強化環状溝の外側壁をパネル部とは反対側へ突出させて形成されている。さらに、缶蓋ｐは、外側壁の角度θ１を０．０°とするとともに、チャック壁の角度θ２を２２．５°とし、強化環状溝の外側壁をパネル部の板厚方向に延出するように形成されている。そして、缶蓋ｑは、強化環状溝の底壁の底面から外側壁の上端までの長さｈ１を３．５ｍｍとし、内面被膜に欠陥が生じないように曲面連結壁を形成して形成されている。また、缶蓋ｒは、外側壁の角度θ１を１．０°とし、強化環状壁の外側壁をパネル部の板厚方向にほぼ延出するように形成されている。
【００４１】
上記の缶蓋Ｃ，Ｄ，Ｅ，Ｆと、缶蓋ｊ，ｋ，...，ｒとについて前記の３つの項目の測定を行った。その結果を表２に示す。
【００４２】
【表２】

表２からわかるように、比較例の缶蓋ｊ，ｋ，...，ｒでは、缶蓋ｎ以外の缶蓋において缶蓋の耐圧強度が所望の値を満たすことができないとともに、缶蓋ｎについてはシャッフル値が所望の値を満たすことができないことがわかる。また、内面被膜の欠陥が不可と判定されている缶蓋も存在することがわかる。一方、本発明の実施例である缶蓋Ｃ，Ｄ，Ｅ，Ｆでは、どちらも缶蓋の耐圧強度とシャッフル値との所望の値を満たしているとともに、内面被膜の欠陥が可と判定されていることがわかる。
【００４３】
【発明の効果】
以上説明したように、請求項１に記載した発明では、パネル部の径方向における曲面連結壁の断面が曲線であり、その曲率半径が０．６６ｍｍ以上９．００ｍｍ以下であることによって、缶蓋にくびれが発生せず、薄板材から缶蓋を成形しても、耐圧強度に優れた缶蓋を得ることができるとともに、内面被膜に亀裂が発生することを防ぐことができる。
【００４４】
さらに強化環状溝の外側壁と曲面連結壁とが、それらの接続部及びその近傍では外周壁の傾斜角に近い角度でパネル部の板厚方向に連続し、外周側に移るのにしたがって徐々に傾斜角を増大するとともに、増大した箇所で缶蓋相互の当接点が存在するので、缶蓋の耐圧強度を向上させたまま缶蓋のシャッフル性を良好なものとすることができる。従って、シーマーへの缶蓋供給作業におけるフランジ・カール部の変形等のトラブルを解消することができるとともに、缶蓋を積層した状態でシュートによって搬送する場合においても、シュート内で缶蓋がブロッキングすることを防ぐことができ、シュート内で蓋詰まりを起こしたり内面被膜に傷がつくことを防ぐことができる。
【００４５】
また、請求項２の発明では、強化環状溝の外側壁がパネル部の中心軸線に対して２°以上１０°以下をなす方向に延出していることによって、強化環状溝のＵ字溝の深さを深くした場合でも、金型に抜き勾配が確保でき、くびれを防ぐことができる。なお、缶蓋成形用金型のクリアランスが板厚よりも小さくなると、金型が缶蓋に食い込むことによって加工硬化を起こしてくびれる。その結果、薄板材から缶蓋を成形しても、缶蓋の耐圧強度を維持することができるとともに、内面被膜に亀裂が発生することを防ぐことができる。また、缶蓋のシャッフル性を維持することができる。
【００４６】
さらに、請求項３の発明では、強化環状溝の内側壁とパネル部の中心軸線とがほぼ平行であることによって、強化環状溝の内側壁と外側壁との強度が向上する。その結果、薄板材から缶蓋を成形しても、耐圧強度に優れた缶蓋を得ることができる。
【図面の簡単な説明】
【図１】 この発明の缶蓋の実施例を示す断面図である。
【図２】 この発明の缶蓋を積層した状態を示す断面図である。
【図３】 従来の缶蓋のパネル部からフランジ部に到る部分の形状の一例を示す部分断面図である。
【図４】 この発明の缶蓋のシャッフル値を測定する説明図である。
【符号の説明】
１…缶蓋、 ２…パネル部、 ３…強化環状溝、 ４…曲面連結壁、 ５…チャック壁、 ６…ショルダー壁、 ７…フランジ・カール部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a can lid used for a positive internal pressure can whose internal pressure is larger than an external pressure.
[0002]
[Prior art]
Carbonated beverages such as cola, cider and beer are gaining popularity in the market. For this reason, a large amount of positive pressure cans that enclose them are produced, and a large number of can lids for positive pressure cans that are fixed to the pressure cans. And from the viewpoint of resource saving and economical viewpoint, the plate thickness of the can lid for the positive internal pressure can is reduced.
[0003]
On the other hand, the can lid for a positive pressure can used for a positive pressure can in which a carbonated beverage is enclosed needs to have a strength sufficient to withstand the pressure of carbon dioxide released from the carbonated beverage. However, when the plate thickness of the can lid is reduced, the strength of the can lid is reduced. Therefore, attempts have been made to reduce the plate thickness without improving the shape of the can lid and reducing its strength.
[0004]
An example of the shape of such a can lid 100 for beverage cans is shown in FIG. 3. This type of can lid 100 usually has a substantially U shape having a bottom wall portion with a radius of curvature (r1) as shown in FIG. A central substantially flat central panel 102 surrounded by a reinforced annular groove 101. The reinforced annular groove 101 includes an inner wall 103 and a countersink outer wall 104. The upper end of the counter sink outer wall 104 is provided with an outer peripheral flange curl portion 106 that extends radially outward through a shoulder wall 105. Further, the end portion of the outer peripheral flange curl portion 106 is bent inward toward the center of the can lid for double winding. In order to improve pressure resistance, the inclination angle of the counter sink outer wall 104 is reduced, the height from the bottom of the central panel 102 (panel height) is increased, and the curvature of the bottom wall of the reinforced annular groove is increased. It is well known in the can manufacturing field to reduce the inner radius.
[0005]
In order to reduce the thickness of the metal material in the can lid and reduce the material cost, it is necessary to improve the rigidity of the lid. As a method for reinforcing the lid, for example, utility model registration No. 2544222 and The one described in JP-A No. 192840 is known. In the former utility model registration No. 2544222, a reinforced annular groove composed of an inner vertical wall, a bottom wall portion and an outer vertical wall is continuously formed on the outer peripheral side of a substantially flat central panel. A can lid having a shape in which a chuck wall is continuously formed on the outer peripheral side of a groove and an end wall for a pressure vessel in a can bottom are disclosed. Since the inner wall and the outer wall of the annular groove are formed perpendicularly, the strength of the portion is improved. As a result, even if the plate thickness of the can lid is made thin, it is possible to make it difficult for the reinforcing annular groove and the central panel to buckle.
[0006]
In the latter Japanese Patent Application Laid-Open No. 8-192840, the inner side wall hangs down from the center panel through the curved part, the curved bottom part continues outward from the inner side wall, and the chuck wall extends upward from the curved bottom part. The can lid is disclosed in which the seaming panel protrudes from the chuck wall. Then, the chuck wall is provided with a bending point, the upper part of the bending wall is the first wall, the lower part is the second wall, and the opening angle of the first wall is made larger than the opening angle of the second wall. When this occurs, the second wall can be mainly deformed to increase the breakdown voltage.
[0007]
[Problems to be solved by the invention]
By providing a vertical wall on a part of the outer wall of the counter sink as described above, it becomes possible to increase the rigidity of the counter sink wall and improve the pressure resistance, and when the internal pressure increases, the plastic deformation of the wall It is considered possible to prevent (buckling). However, in aluminum can lids, which are less extensible than steel, the connection between the chuck wall and the outer vertical wall is subject to work hardening as the thickness is reduced, and this part tends to be constricted. The stress concentrates on the surface, making it easy to cause plastic fracture from this portion, which is a technical obstacle in improving the pressure resistance with a thin wall. In addition, in the case of an aluminum can lid in which the inner surface side of the can is coated with a resin, cracks are likely to occur in the coating due to constriction, and there is a problem that the coating performance is deteriorated due to damage of the resin coating.
[0008]
On the other hand, when the can lids are supplied one by one from the seamer stacker, so-called lid cutting is performed to take out the can lids one by one with the separator knife and the separator roll. If the cover is installed, the lateral displacement of the lid will be small and the shuffling property (a guide to guaranteeing the flowability of the cover with the seamer) will deteriorate, so the separator knife will be inserted between the stacked can lids This makes it difficult to cover the lid with the seamer, or makes it difficult to insert a separator knife, so that the end of the flange / curl portion is easily crushed or deformed. Due to the deformation of the flange curl portion, there is a risk of causing a leakage can without obtaining proper winding. Furthermore, since it is transported in a block state inside the can lid transport chute to a stacker, etc., smooth transport cannot be expected and productivity is lowered, and the outer surface of the can lid is easily squeezed by a chute guide etc. There is a problem that leads to a large defect, such as a reduction.
[0009]
Furthermore, the pressure resistance performance varies depending on the constriction position, and variations in the pressure resistance strength are likely to occur. Therefore, the adjustment of the height position of the constriction necessitates a fine adjustment in the production process.
[0010]
The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a can lid for a positive pressure can that can maintain practical performance, strength and shuffle even when a thin plate material is used. It is what.
[0011]
[Means for Solving the Problem and Action]
In order to achieve the above object, according to the invention of claim 1, a reinforced annular groove having a U-shaped cross section recessed in the plate thickness direction of the panel part is formed on the outer periphery of the substantially disk-shaped panel part. The inner wall of the reinforced annular groove is continuous so as to extend in the plate thickness direction of the panel portion, and the bottom wall of the reinforced annular groove is continuous with the radially outer side of the panel portion on the outer peripheral side of the inner wall. Furthermore, the outer wall of the reinforced annular groove extends to the outer peripheral side of the bottom wall so as to face the inner wall in the radial direction of the panel portion, and the outer wall of the outer wall is connected to the outer peripheral side of the outer wall. A curved connecting wall having a curved section cut along the central axis direction of the panel portion is continuous so as to extend in the plate thickness direction of the panel portion, and a tapered cylindrical shape is formed on the outer peripheral side of the curved connecting wall. A chuck wall is formed continuously, and a rack is formed on the outer peripheral side of the chuck wall. A shoulder-shaped shoulder wall is continuous, and further, a flange curl portion extending outward in the radial direction of the panel portion on the outer peripheral side of the shoulder wall and having an outer peripheral end bent back inward in the radial direction is continuous. In the formed can lid for a positive internal pressure can, the angle formed by the chuck wall and the central axis of the panel portion is 10 ° or more and 20 ° or less, and the curved connecting wall is convex toward the panel portion side. And the curvature radius of the convex portion is 0.66 mm or more and 9.00 mm or less, and the inner curvature circle of the outer peripheral side bottom wall of the reinforced annular groove connected to the curved connecting wall and the curved connecting wall The maximum distance from the common tangent line connecting the outer curvature circle of the connected shoulder wall to the protruding portion of the curved connecting wall is 10% or more and 50% or less of the thickness of the panel portion, and the layers are laminated in the same direction. Radial direction in the state When shifted to one in which the one of the curved connecting wall and the other reinforcing annular groove of the bottom wall is characterized in that it is formed so as to abut.
[0012]
Therefore, according to the invention of claim 1, the can lid is constricted when the cross section of the curved connecting wall in the radial direction of the panel portion is a curve and the radius of curvature is 0.66 mm or more and 9.00 mm or less. Even if the can lid is molded from a thin plate material, it is possible to obtain a can lid having excellent pressure strength and to prevent the inner coating from cracking.
[0013]
Furthermore, the outer wall of the reinforced annular groove and the curved connecting wall are continuous in the plate thickness direction of the panel portion at an angle close to the inclination angle of the outer peripheral wall in the connection portion and the vicinity thereof, and gradually move toward the outer peripheral side. Since the inclination angle is increased and there is a contact point between the can lids at the increased location, the can lid can be shuffled while the pressure resistance of the can lid is improved. Therefore, troubles such as deformation of the flange / curl portion during supply of the can lid to the seamer can be solved, and even when the can lid is stacked and transported by the chute, the can lid blocks in the chute. This can prevent the clogging of the lid within the chute and prevent the inner surface film from being damaged.
[0014]
In addition to the invention of claim 1, the invention of claim 2 is formed such that an angle formed by the outer wall of the reinforced annular groove and the central axis of the panel portion is 2 ° or more and 10 ° or less. It is characterized by being.
[0015]
Therefore, according to the second aspect of the present invention, the outer wall of the reinforced annular groove extends in a direction that forms 2 ° or more and 10 ° or less with respect to the central axis of the panel portion. Even when the depth is increased, a draft can be secured in the mold, and constriction can be prevented. When the clearance of the can lid forming mold is smaller than the plate thickness, the mold bites into the can lid, causing work hardening. As a result, even if the can lid is formed from a thin plate material, the pressure resistance of the can lid can be maintained and cracks can be prevented from occurring in the inner surface coating. Moreover, the shuffle property of the can lid can be maintained.
[0016]
The invention of claim 3 is characterized in that, in addition to the invention of claim 1 or 2, the inner wall of the reinforced annular groove is substantially parallel to the central axis of the panel portion. is there.
[0017]
Therefore, according to the invention of claim 3, the strength of the inner side wall and the outer side wall of the reinforced annular groove is improved because the inner side wall of the reinforced annular groove and the central axis of the panel portion are substantially parallel. As a result, even if a can lid is molded from a thin plate material, a can lid having excellent pressure strength can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows one embodiment of the present invention, and a can lid for a positive internal pressure can (hereinafter simply referred to as a can lid) 1 is usually made of an aluminum alloy flat plate (not shown). It is formed using a known molding die. Note that an inner surface coating (not shown) made of a synthetic resin is formed in advance on one surface of the flat plate material. This inner surface film is formed from a protective paint or a resin film. As the paint, any protective paint made of thermosetting and thermoplastic resin, for example, modified epoxy paint such as phenol-epoxy paint, amino-epoxy paint, vinyl chloride-vinyl acetate copolymer, epoxy phenol modified-vinyl paint These are used alone or in combination of two or more, such as vinyl or modified vinyl paint. As the resin film, for example, polyethylene terephthalate (PET) is used as a basic component, and a copolymer such as polyethylene isophthalate (PEIT) can also be applied. When a resin film is used for the inner surface coating, the resin film may be unstretched or biaxially stretched, and preferably has a thickness of 8 μm or more and 25 μm or less. This is because if the thickness is less than 8 μm, it is difficult to sufficiently protect the can lid 1 by the inner surface coating even if it depends on the contents of the can body, and if the thickness exceeds 25 μm, the inner surface The material used for the coating becomes excessive, which is not preferable.
[0019]
A disc-shaped panel portion 2 is formed at the center of the can lid 1. Further, a reinforced annular groove 3 formed by an inner wall 3a, a bottom wall 3b, and an outer wall 3c is formed on the outer periphery of the panel portion 2 in a U-shape that is recessed substantially downward in FIG. . The bottom wall 3b and the outer wall 3c are connected to form a curved surface having a constant radius of curvature r. The outer wall 3c is formed so as to extend from the direction along the central axis of the panel portion 2 in a direction that forms an angle θ1. The angle θ1 is 2 ° or more and 10 ° or less. The reason why the angle θ1 is 2 ° or more is that if the angle θ1 is less than 2 °, the pressure resistance strength and shuffle property when a plurality of can lids 1 are stacked may be reduced. For example, when the angle θ1 is 0 °, that is, when the outer wall 3c extends in the same direction as the direction along the central axis of the panel portion 2, the shuffle value (length s represented by FIG. 4) is from 1.0 mm. Becomes smaller and the shuffling property is lowered. Furthermore, when the can lid 1 is adopted as a can lid of a can body in which a carbonated beverage such as cola or beer is enclosed, the inner wall 3a is oriented along the central axis of the panel portion 2, that is, the vertical direction in FIG. It is desirable that the can lid 1 be formed so as to extend in a pressure-resistant manner.
[0020]
Then, a curved connecting wall 4 is formed extending substantially upward in FIG. 1 from the outer wall 3 c of the reinforced annular groove 3. The curved connecting wall 4 has a curved surface shape having a certain radius of curvature R, and the center of the radius of curvature exists on the side opposite to the panel portion 2 side. That is, the curved connection wall 4 is formed so as to swell and protrude toward the panel portion 2 side. Then, as shown in FIG. 2, when a plurality of can lids 1 are stacked in the same direction, on the surface of the curved connecting wall 4 of a certain can lid 1 on the panel part 2 side (surface on the can outer surface side), A curved connecting wall 4 is formed so that the outer surface of the reinforcing annular groove 3 of the can lid 1 adjacent thereto can abut.
[0021]
Further, a tapered chuck wall 5 is formed so as to extend from the curved connecting wall 4 substantially upward in FIG. The chuck wall 5 is formed so as to extend from the direction along the central axis of the panel portion 2 in a direction that forms an angle θ2. And this angle (theta) 2 is larger than the above-mentioned angle (theta) 1, and is 10 degrees or more and 20 degrees or less. If the angle θ2 is less than 10 °, it is difficult to insert a chuck tool when the can lid 1 is wound around a cylindrical can body (not shown), and the fitting with the chuck is difficult. It becomes loose and tends to cause a sealing failure during double winding. Further, when the angle θ2 exceeds 20 °, the shuffle performance is deteriorated in the state where the reinforced annular groove 3 is maintained. On the other hand, in the state where the shuffling property is maintained, the diameter of the reinforcing annular groove 3 in the radial direction of the can lid 1 must be reduced, and the diameter of the panel is also reduced accordingly. In the case of an easy open can lid such as a steion tab type, the position of an opening (not shown) formed in the panel portion 2 for allowing the contents of the can body to flow out becomes farther than the tightening portion. When a person tilts a can body and drinks the contents from the opening part of the can lid 1, the problem that it becomes difficult to drink arises.
[0022]
The angle θ2 is made larger than the angle θ1 because the curved connecting wall 4 swells and protrudes on the side opposite to the panel portion 2 when the angle θ2 is equal to or smaller than the angle θ1. This is because there is a possibility that the pressure strength of the material may be reduced.
[0023]
Further, a trumpet-shaped shoulder wall 6 extending from the upper end of the chuck wall 5 substantially upward in FIG. 1 is formed. A flange curl portion 7 is formed extending from the shoulder wall 6 in the left direction in FIG. The flange curl portion 7 is formed by curling the edge of the can lid 1 so as to be rounded. The length T (curl thickness) between the upper end and the lower end of the flange curl portion 7 in the direction along the central axis of the panel portion 2 is 2.0 mm or more and 2.3 mm or less. And this flange curl part 7 is wound around the opening edge part of a cylindrical can body (not shown), the can lid 1 is fixed to the can body, and a positive internal pressure can (not shown) is formed. Is done.
[0024]
In addition, the plate | board thickness of the can lid 1 is 0.220 mm or more and 0.335 mm or less. This is because when the plate thickness is 0.220 mm or less, the pressure resistance of the can lid 1 decreases, so that the bottom wall 3b and the outer wall 3c of the reinforced annular groove 3 are connected to maintain the pressure resistance of the can lid 1. It is necessary to make the curvature radius r of the portion to be 0.35 mm or less. In that case, in the molding process of the can lid 1, the can lid 1 may be constricted and a crack may occur in the bottom wall 3 b. On the other hand, if the plate thickness is 0.335 mm or more, the material used for the can lid 1 becomes excessive, which is not economical.
[0025]
Further, when the length h1 from the bottom wall 3b of the reinforcing annular groove 3 to the upper end of the outer wall 3c in the direction along the central axis of the panel part 2 is t, the thickness of the panel part 2 is t, and the stack thickness is k. r + t) and less than (k + r + t). This is because, when h1 is too small, when the can lid 1 is molded by a conventionally known can lid molding die (for example, one described in JP-A-60-170540), Since the chuck wall 5 approaches the common tangent line L (the common tangent line between the shoulder wall 6 and the portion connecting the bottom wall 3b and the outer peripheral wall 3c of the reinforced annular groove 3), the curved connecting wall 4 swells and protrudes toward the panel portion 2 side. If it is going to be molded in such a manner, the can lid 1 may be constricted or its inner coating may be damaged. On the other hand, when h1 is too large, the position of the curved connecting wall 4 that protrudes toward the panel portion 2 is present above in FIG. 1, and the strength of the can lid 1 may not be improved. . Further, the length of the chuck wall 5 in the direction along the center axis of the panel portion 2 must be shortened, and when the can lid 1 is wound around the can body, normal winding may not be obtained. In addition, the airtightness of the formed can body may be impaired.
[0026]
Further, the curved connecting wall 4 described above is formed so that the radius of curvature R is 0.66 mm or more and 9.00 mm or less. This is due to the following reason. When the curvature radius R of the curved connecting wall 4 is less than 0.66 mm, the curved connecting wall 4 may be constricted when the curved connecting wall 4 is formed. Then, when the constriction occurs, there is a possibility that a crack may occur in the inner surface coating covering the portion of the curved connecting wall 4 where the constriction occurs. Further, when the curvature radius R of the curved connecting wall 4 exceeds 9.00 mm, the protruding length that protrudes toward the panel portion 2 side becomes small, and the protruding position exists above in FIG. It is insufficient to improve the strength of the can lid 1.
[0027]
The curved connecting wall 4 is formed so that the maximum distance from the common tangent L to the protruding portion of the curved connecting wall 4 is 10% or more and 50% or less of the plate thickness of the can lid 1. If it is less than 10%, the strength of the can lid 1 cannot be improved by the curved connecting wall 4. Further, when it exceeds 50%, the shuffle value becomes less than 1.0 mm, and when the laminated can lid 1 is separated by the separator knife, the separator knife is interposed between the can lid 1 and the can lid 1. In addition to being easily inserted, the flange and curl portion 7 of the can lid 1 may be deformed or damaged by the separator knife. Further, when the can lids 1 are transported, once the can lids 1 overlap with each other, the can lids 1 are in close contact with each other and do not easily follow the guide of the chute, causing a blocking phenomenon, There is a possibility that the can lid 1 is clogged and the productivity is lowered.
[0028]
Further, the length (counter sink depth) h2 from the upper surface of the reinforcing annular groove 3 to the bottom wall 3b to the upper end surface of the flange curl portion 7 in the direction along the center axis of the panel portion 2 is 6.0 mm or more. The length (panel height) h3 between the upper surface of the panel part 2 and the bottom wall 3b of the reinforced annular groove 3 in the direction along the central axis of the panel part 2 is 1.1 mm or more and 2.4 mm or less to 1 mm or less. Thus, the can lid 1 is formed. In addition, when employ | adopting as a can lid | cover of the can body in which carbonated drinks, such as cola and beer, are enclosed, it is desirable to set h3 comparatively long and aim at the pressure | voltage resistant reinforcement of the can lid | cover 1. FIG.
[0029]
Next, an experiment for demonstrating the effect of the can lid 1 for a positive internal pressure can according to an embodiment of the present invention will be described. First, a plurality of can lids 1 in which 5182 series aluminum was used as the material aluminum were prepared, and the following three items were measured.
[0030]
First, the pressure strength of the can lid 1 was measured as a first measurement item. First, the can lid 1 is squeezed and wound around the can body, then the bottom of the can body is opened, gas pressure is applied to the inside of the can body by a pressure-resistant inspection device, and a part of the reinforced annular groove 3 of the can lid 1 is formed. The pressure at the time when the first rounding (buckling) occurred was measured with a recorder.
[0031]
Further, as a second measurement item, the surface of the can lid 1 which is the inner surface of the can body (the lower surface in FIG. 1) is faced up, and the thickness of the flange curl portion 7 of the can lid 1 as shown in FIG. A plurality of can lids 1 were stacked until the total amount reached about 50.8 mm, and sequentially shifted laterally from the lower can lid 1, and the shuffle value (lateral displacement amount) s was measured with a shuffle gauge or a caliper.
[0032]
Further, as a third measurement item, copper sulfate is dissolved in acetone, the can lid 1 is immersed in the solution for 10 minutes, then washed with water, and the corrosion state of the inner surface coating located in the reinforced annular groove 3 by a stereomicroscope. Was measured. And when the corroded point is a point and up to five points are generated, the can lid 1 is allowed, and the corrosive point occurs over the surface instead of the corrosive point 6 points or more. If it is, the can lid 1 was determined to be impossible.
[0033]
[Example 1]
First, two types of can lids are prepared as the can lid 1 of the present invention. These can lids A and B are made of 5182-H39 aluminum alloy, have a plate thickness of 0.235 mm, and have a phenol-epoxy paint applied to the inner surface of the can body at 110 mg / dm 2 and baked and cured. The can lids A and B have an outer diameter of the flange curl portion of 57.20 mm (lid name: 200), and the length from the upper surface of the bottom wall 3b of the reinforced annular groove 3 to the upper end surface of the flange curl portion 7 The length h2 is 6.05 mm, the curvature radius r of the portion connecting the bottom wall 3b and the outer wall 3c of the reinforced annular groove is 0.66 mm, the curvature radius R of the curved connection wall 4 is 0.66 mm, and the curvature of the shoulder wall 6 It is formed such that the radius is 2.00 mm, the panel height h3 is 1.3 mm, and the length T between the upper end and the lower end of the flange curl portion 7 is 2.10 mm. The can lid A has an angle θ1 of 6.3 °, an angle θ2 of 16.0 ° and a length h1 of 1.3 mm, and the ratio of the maximum protruding length of the curved connecting wall 4 to the plate thickness is 38.7. %It has become. The can lid B has an angle θ1 of 6.5 °, an angle θ2 of 15.0 ° and a length h1 of 1.0 mm, and the ratio of the maximum protruding length of the curved connecting wall 4 to the plate thickness is 16.6. %It has become.
[0034]
Also, nine types of can lids are prepared as comparative example can lids. These can lids a, b,..., I have the same shape as the can lid A which is a can lid 1 for a positive internal pressure can according to the present invention unless otherwise specified. The can lid a is formed so that the inclination angle θ2 of the chuck wall is 19.9 ° and the outer wall of the reinforced annular groove extends in the thickness direction of the panel portion. Further, the can lid b is formed such that the inclination angle θ2 of the chuck wall is 14.4 ° and the protruding length of the curved connecting wall is zero. Further, the can lid c is formed with a curvature radius R of the curved connecting wall of 10.00 mm. The can lid d and the can lid e are formed by changing the angle θ1 and the angle θ2 so that the protruding length of the curved connecting wall is excluded from the range of the protruding length of the curved connecting wall in the can lid 1 of the present invention. Has been.
[0035]
The can lid f is formed by projecting the outer wall of the reinforced annular groove to the opposite side of the panel portion so that the angle θ2 of the chuck wall is 9.0 ° and θ1 is larger than θ2. . Further, the can lid g is formed by setting the angle θ2 of the chuck wall to 22.5 ° and forming a curved connecting wall so that the inner surface coating does not have a defect. The can lid h is formed by forming a curved connecting wall so that the length h1 from the bottom surface of the bottom wall of the reinforced annular groove to the upper end of the outer wall is 3.2 mm, and the inner surface coating is not defective. Yes. Further, the can lid i is formed so that the angle θ1 of the outer wall is 0.0 ° and the outer wall of the reinforced annular wall extends in the plate thickness direction of the panel portion.
[0036]
The above three items were measured for the can lids A and B and the can lids a, b,. The results are shown in Table 1.
[0037]
[Table 1]

As can be seen from Table 1, each of the can lids a, b,..., I of the comparative example shows that at least one of the pressure resistance and shuffle value of the can lid cannot satisfy a desired value. . Moreover, it turns out that the can lid | cover with which the defect of an inner surface film was determined to be impossible also exists. On the other hand, in the can lids A and B which are the embodiments of the present invention, both satisfy the desired values of the pressure resistance and shuffle value of the can lid, and it is determined that the defect of the inner surface coating is acceptable. Recognize.
[0038]
[Example 2]
On the other hand, four types of can lids are prepared as the can lid 1 of the present invention. These can lids C, D, E, and F are made of 5182-H38 aluminum alloy, the plate thickness is 0.26 mm, and the vinyl chloride organosol coating is applied to the inner surface of the can body by 140 mg / dm 2 and baked and cured. Has been. The can lids C, D, E, and F have an outer diameter of the flange / curl portion of 64.65 mm (lid name 206), and are located above the flange / curl portion 7 from the upper surface of the bottom wall 3b of the reinforced annular groove 3. The length h2 to the end surface is 6.90 mm, the radius of curvature r of the portion connecting the bottom wall 3b and the outer wall 3c of the reinforced annular groove is 0.35 mm, the radius of curvature of the shoulder wall 6 is 1.80 mm, the panel tool h3 Is 2.3 mm, and the length T between the upper end and the lower end of the flange curl portion 7 is 2.28 mm. The can lid C has a curvature radius R of the curved connecting wall 4 of 7.00 mm, an angle θ1 of 6.5 °, an angle θ2 of 13.5 °, and a length h1 of 1.8 mm. The ratio of the maximum protruding length to the plate thickness is 46.5%. Further, the can lid D has a curvature radius R of the curved connecting wall 4 of 3.50 mm, an angle θ1 of 7.5 °, an angle θ2 of 13.5 °, and a length h1 of 2.2 mm. The ratio of the maximum protruding length to the plate thickness is 45.4%. Further, the can lid E has a curvature radius R of the curved connecting wall 4 of 0.66 mm, an angle θ1 of 8.5 °, an angle θ2 of 13.0 °, and a length h1 of 2.5 mm. The ratio of the maximum protruding length to the plate thickness is 37.3%. Further, the can lid F has a curvature radius R of the curved connecting wall 4 of 7.00 mm, an angle θ1 of 5.0 °, an angle θ2 of 13.5 °, and a length h1 of 1.3 mm. The ratio of the maximum protruding length to the plate thickness is 50.0%.
[0039]
Also, nine types of can lids are prepared as comparative example can lids. These can lids j, k,..., R have the same shape as the can lid C which is the can lid 1 of the present invention unless otherwise specified. The can lid j is formed so that the inclination angle θ2 of the chuck wall is 13.5 ° and the outer wall of the reinforced annular groove extends in the thickness direction of the panel portion. Further, the can lid k is formed such that the inclination angle θ2 of the chuck wall is 11.2 ° and the protruding length of the curved connecting wall is zero. Further, the can lid 1 is formed with a curvature radius R of the curved connecting wall of 10.00 mm. The can lid m and the can lid n are formed by changing the angle θ1 and the angle θ2 to exclude the protruding length of the curved connecting wall from the range of the protruding length of the curved connecting wall in the can lid 1 of the present invention. Has been.
[0040]
The can lid o is formed by projecting the outer wall of the reinforced annular groove to the opposite side of the panel portion so that the angle θ2 of the chuck wall is 9.0 ° and θ1 is larger than θ2. . Further, the can lid p has an outer wall angle θ1 of 0.0 ° and a chuck wall angle θ2 of 22.5 °, and extends the outer wall of the reinforced annular groove in the thickness direction of the panel portion. It is formed as follows. The can lid q is formed by forming a curved connecting wall so that the length h1 from the bottom surface of the bottom wall of the reinforced annular groove to the upper end of the outer wall is 3.5 mm, and the inner surface coating is not defective. Yes. The can lid r is formed so that the angle θ1 of the outer wall is 1.0 ° and the outer wall of the reinforced annular wall extends substantially in the thickness direction of the panel portion.
[0041]
The above three items were measured for the can lids C, D, E, and F and the can lids j, k,. The results are shown in Table 2.
[0042]
[Table 2]

As can be seen from Table 2, in the can lids j, k,..., R of the comparative example, the pressure resistance of the can lid cannot satisfy the desired value in the can lids other than the can lid n, and the can lid n It can be seen that the shuffle value cannot satisfy the desired value. Moreover, it turns out that the can lid | cover with which the defect of an inner surface film was determined to be impossible also exists. On the other hand, in can lids C, D, E, and F which are embodiments of the present invention, both satisfy the desired values of the pressure resistance and shuffle value of the can lid, and it is determined that the defect of the inner surface coating is acceptable. You can see that
[0043]
【The invention's effect】
As described above, in the invention described in claim 1, the cross section of the curved connecting wall in the radial direction of the panel portion is a curve, and the radius of curvature is 0.66 mm or more and 9.00 mm or less. Necking does not occur, and even if a can lid is molded from a thin plate material, a can lid having excellent pressure strength can be obtained, and cracks can be prevented from occurring in the inner surface coating.
[0044]
Further, the outer wall of the reinforced annular groove and the curved connecting wall are continuous in the plate thickness direction of the panel portion at an angle close to the inclination angle of the outer peripheral wall at the connection portion and in the vicinity thereof, and gradually move toward the outer peripheral side. Since the inclination angle is increased and there is a contact point between the can lids at the increased location, the can lid can be shuffled while the pressure resistance of the can lid is improved. Therefore, troubles such as deformation of the flange / curl portion in the can lid supply operation to the seamer can be solved, and even when the can lid is stacked and transported by the chute, the can lid blocks in the chute. This can prevent the clogging of the lid within the chute and prevent the inner surface film from being damaged.
[0045]
In the invention according to claim 2, the outer wall of the reinforced annular groove extends in a direction that forms 2 ° or more and 10 ° or less with respect to the central axis of the panel portion. Even when the depth is increased, a draft can be secured in the mold, and constriction can be prevented. When the clearance of the can lid forming mold is smaller than the plate thickness, the mold bites into the can lid, causing work hardening. As a result, even if the can lid is formed from a thin plate material, the pressure resistance of the can lid can be maintained and cracks can be prevented from occurring in the inner surface coating. Moreover, the shuffle property of the can lid can be maintained.
[0046]
Furthermore, in the invention of claim 3, the strength of the inner side wall and the outer side wall of the reinforced annular groove is improved because the inner side wall of the reinforced annular groove and the central axis of the panel portion are substantially parallel. As a result, even if a can lid is molded from a thin plate material, a can lid having excellent pressure strength can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a can lid according to the present invention.
FIG. 2 is a cross-sectional view showing a state in which can lids of the present invention are stacked.
FIG. 3 is a partial cross-sectional view showing an example of a shape of a portion from a panel portion to a flange portion of a conventional can lid.
FIG. 4 is an explanatory diagram for measuring a shuffle value of a can lid according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Can lid, 2 ... Panel part, 3 ... Reinforced annular groove, 4 ... Curve connection wall, 5 ... Chuck wall, 6 ... Shoulder wall, 7 ... Flange curl part.

Claims (3)

A reinforced annular groove having a U-shaped cross section that is recessed in the thickness direction of the panel portion is formed on the outer periphery of the substantially disk-shaped panel portion, and the inner side wall of the reinforced annular groove extends in the thickness direction of the panel portion. The bottom wall of the reinforced annular groove continuously extends so as to extend on the outer circumferential side of the inner wall thereof, and further extends radially outward of the panel portion, and further, the reinforced annular groove is disposed on the outer circumferential side of the bottom wall. A shape in which the outer wall of the groove extends and continues so as to face the inner wall in the radial direction of the panel portion, and the cross section cut along the central axis direction of the panel portion on the outer peripheral side of the outer wall is curved. A curved connecting wall that extends in the thickness direction of the panel portion, a tapered cylindrical chuck wall is continuously formed on the outer peripheral side of the curved connecting wall, and the outer periphery of the chuck wall A trumpet-shaped shoulder wall is continuous on the side, and the shoulder Extending radially outwardly of the panel portion on the outer peripheral side of the over the wall, the positive pressure can lid for a can of flange curl portion is formed continuously with a radially inwardly bent returned outer peripheral edge,
An angle formed by the chuck wall and the central axis of the panel portion is 10 ° or more and 20 ° or less,
The curved connecting wall has a shape that is convex toward the panel portion, and the radius of curvature of the convex portion is 0.66 mm to 9.00 mm,
From the common tangent line connecting the inner curvature circle of the outer peripheral bottom wall of the reinforced annular groove connected to the curved connection wall and the outer curvature circle of the shoulder wall connected to the curved connection wall, the curved connection wall The maximum distance to the projecting portion is 10% or more and 50% or less of the plate thickness of the panel portion,
A can for a positive internal pressure can characterized by being formed so that one curved connecting wall and the bottom wall of the other reinforcing annular groove are in contact with each other when shifted in the radial direction in a state of being laminated in the same direction lid. 2. The can lid for a positive pressure can according to claim 1, wherein an angle formed between an outer wall of the reinforced annular groove and a central axis of the panel portion is 2 ° or more and 10 ° or less. . The can lid for a positive internal pressure can according to claim 1 or 2, wherein an inner wall of the reinforced annular groove is substantially parallel to a central axis of the panel portion.

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