JP2000109068A - Can lid for can having positive internal pressure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a can lid for can having positive internal pressure wherewith a performance and a strength which are endurable to practical use and shuffling property can be maintained even when a thin sheet material is used. SOLUTION: A can lid 1 is formed in a structure wherein an angle made up by a chuck wall 5 and a direction along the central axis of a panel part 2 is 10-20 deg. and while a curved connecting wall 4 is formed in a shape projecting toward the panel part 2 side, the radius of curvature for a curved line of the curved connecting wall 4 is 0.66-9.00 mm, the maximum distance from a common tangent line connecting a circle of curvature at the inside of an outer circumferential bottom wall of a reinforcing annular groove 3 connecting to the curved connecting wall 4 and a circle of curvature at the outside of a shoulder wall 6 connecting to the curved connecting wall 4 to a projected part of the curved connecting wall 4 is 10-50% of the thickness of the aforementioned panel part and at the same time, the curved connecting wall 4 at one side comes into contact with a bottom wall 3b of the reinforcing annular groove 3 at another side when sliding-off is made between both members after a plurality of can lids are piled up in the same direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can lid used for a positive internal pressure can having an internal pressure of a can body larger than an external pressure.

[0002]

2. Description of the Related Art Carbonated beverages represented by cola, cider, beer and the like have been well received in the market. for that reason,
Positive internal pressure cans for enclosing them are produced in large quantities, and can lids for positive internal pressure cans adhered thereto are also produced in large quantities. Then, from the viewpoint of resource saving and economical viewpoint, the thickness of the can lid for positive internal pressure cans is reduced.

[0003] On the other hand, a positive internal pressure can lid used for a positive internal pressure can in which a carbonated beverage is sealed needs to have strength enough to withstand the pressure caused by carbon dioxide released from the carbonated beverage. However, when the thickness of the can lid is reduced,
The strength of the can lid decreases. For this reason, attempts have been made to improve the shape of the can lid to reduce its thickness without reducing its strength.

As an example of the shape of the can lid 100 for beverage cans, this type of can lid 100 generally has a bottom wall portion having a radius of curvature (r1) as shown in FIG. It comprises a central, substantially flat central panel 102 surrounded by a U-shaped reinforced annular groove 101. Its reinforced annular groove 101
Has an inner wall 103 and a countersink outer wall 104. The upper end of the countersink outer wall 104 is provided with an outer peripheral flange curl portion 106 extending radially outward via a shoulder wall 105. Further, the distal end portion of the outer peripheral flange / curl portion 106 is bent inward toward the center of the can lid for double winding. Then, in order to improve the pressure resistance, the inclination angle of the countersink outer wall 104 is reduced,
It is well known and used in the field of cans to increase the height (panel height) from the bottom of 2, and to reduce the inner radius of curvature of the bottom wall of the reinforcing annular groove.

In order to reduce the thickness of the metal material in the can lid to reduce the material cost, it is necessary to improve the rigidity of the lid. As a method of reinforcing the lid, for example, Japanese Utility Model Registration No. 2544222 or JP-A-8-19284
No. 0 is known. In the former Japanese Utility Model Registration No. 2544222, a reinforced annular groove composed of an inner vertical wall, a bottom wall, and an outer vertical wall is continuously formed on the outer peripheral side of a substantially flat central panel. Disclosed are a can lid having a shape in which a chuck wall is continuous on the outer peripheral side of the groove and an end wall for a pressure-resistant container at a can bottom.
Since the inner wall and the outer wall of the annular groove are formed vertically, the strength of that portion is improved. as a result,
Even if the thickness of the can lid is reduced, buckling of the reinforced annular groove and the center panel can be suppressed.

In the latter Japanese Patent Application Laid-Open No. Hei 8-192840, an inner side wall hangs down from a center panel via a curved portion, a curved bottom portion continues outward from the inner side wall, and an upper portion extends upward from the curved bottom portion. Discloses a can lid in which a chuck wall rises and a seaming panel projects from the chuck wall. By providing a bending point on the chuck wall and setting the upper part of the chuck wall above the bending point as the first wall and the lower part as the second wall, the opening angle of the first wall is made larger than the opening angle of the second wall. However, the second wall is mainly deformed, so that the withstand voltage can be increased.

[0007]

As described above, by providing a vertical wall at a part of the outer wall of the countersink, it is possible to increase the rigidity of the countersink wall and improve the pressure resistance, thereby increasing the internal pressure. If this happens, it is considered possible to prevent plastic deformation (buckling) of the wall. However, in aluminum can lids, which are less extensible than steel, the connection between the chuck wall and the outer vertical wall tends to work harden due to the reduction in thickness, and constriction is likely to occur in this part. Stress tends to be concentrated on this portion, and plastic breakage is likely to occur 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 of the can is coated with a resin, cracks easily occur in the coating due to constriction, and there is a problem in that the coating performance is reduced due to damage to the resin coating.

On the other hand, the can lid is removed from the seamer stacker by one.
When the sheets are supplied one by one, the so-called lid-cutting is performed, in which the can lid is removed one by one with a separator knife and a separator roll. However, if a vertical wall is provided outside the counter sink to increase rigidity, the lateral displacement of the lid is small. As a result, the shuffling property (cutting the lid with a seamer, a measure to guarantee flowability) deteriorates, so it becomes difficult for the separator knife to enter between the stacked can lids and can lids. The end of the flange / curl portion is easily crushed or deformed because it causes troubles or makes it difficult for the separator knife to enter. Due to the deformation of the flange and curl portion, there is a danger of causing a leak can without obtaining normal winding. In addition, since it is transported in a block state in the can lid transport chute to the stacker, etc., smooth transport cannot be expected, reducing productivity, and the outer surface of the can lid is easily squeezed by a chute guide etc. There is a problem that leads to major defects such as reduction.

Further, the pressure resistance varies depending on the constricted position, and the pressure resistance tends to vary, so that the setting of the constricted height position requires fine adjustment, which causes inconvenience in the production process.

The present invention has been made in view of the above circumstances, and provides a can lid for a positive internal pressure can that can maintain the performance, strength, and shuffling properties that can withstand practical use even when a thin plate is used. The purpose is to do so.

[0011]

In order to achieve the above-mentioned object, the invention according to the first aspect of the present invention is directed to a method of forming a cross section U which is recessed in the thickness direction of the panel portion on the outer periphery of the substantially disk-shaped panel portion. A reinforced annular groove having a V-shape is formed, the inner wall of the reinforced annular groove is continuous so as to extend in the thickness direction of the panel portion, and the bottom of the reinforced annular groove is formed on the outer peripheral side of the inner wall. A wall continuously extends radially outward of the panel portion, and further extends outwardly of the bottom wall such that an outer wall of the reinforcing annular groove faces the inner wall in a radial direction of the panel portion. Continuous to the outer peripheral side of the outer wall so that a curved surface connecting wall having a curved cross section cut along the central axis direction of the panel portion 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 a trumpet-shaped shoulder wall continues on the outer peripheral side of the chuck wall, and further extends outward in the radial direction of the panel portion on the outer peripheral side of the shoulder wall, and is bent back inward in the radial direction. In a can lid for a positive internal pressure can in which a flange curl portion having an end is continuously formed, an angle between the chuck wall and a central axis of the panel portion is 10 ° or more and 20 ° or less, and the curved surface connecting wall is formed. Has a shape that is convex toward the panel portion side, and the radius of curvature of the convex portion is 0.66 mm or more and 9.0.
0 mm or less, from a common tangent line connecting the inner curvature circle of the outer peripheral bottom wall of the reinforcing annular groove connected to the curved connection wall and the outer curvature circle of the shoulder wall connected to the curved connection wall. When the maximum distance to the projecting portion of the curved surface connecting wall is 10% or more and 50% or less of the thickness of the panel portion, and when it is shifted in the radial direction while being stacked in the same orientation, one curved surface connecting wall and It is characterized in that it is formed so as to contact the bottom wall of the other reinforcing annular groove.

Therefore, according to the first aspect of the present invention, 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, so that the can lid can be formed. Even if a can lid is formed from a thin plate material without causing constriction, it is possible to obtain a can lid excellent in pressure resistance and prevent a crack from being generated in the inner coating.

Further, the outer wall and the curved connecting wall of the reinforced annular groove are continuous with each other in the thickness direction of the panel portion at an angle close to the inclination angle of the outer peripheral wall in the connection portion and in the vicinity thereof, and move to the outer peripheral side. Therefore, the inclination angle is gradually increased, and the contact points between the can lids are present at the increased locations, so that the shuffling property of the can lid can be improved while the pressure resistance of the can lid is improved. Therefore, troubles such as deformation of the flange / curl portion in the operation of supplying the can lid to the seamer can be eliminated, and when the can lids are transported by the chute in a stacked state, the can lid blocks in the chute. This can prevent the clogging of the lid in the chute and the damage to the inner surface coating.

According to a second aspect of the present invention, in addition to the first aspect, the angle between the outer wall of the reinforcing annular groove and the center axis of the panel portion is 2 ° or more and 10 ° or less. It is characterized by being formed.

Therefore, according to the second aspect of the present invention, the outer wall of the reinforced annular groove has an angle of 2 ° or more with respect to the center axis of the panel portion.
By extending in a direction of 0 ° or less, even when the depth of the U-shaped groove of the reinforcing annular groove is increased, a draft angle can be secured in the mold, and constriction can be prevented. If the clearance of the mold for forming a can lid is smaller than the plate thickness, the mold bites into the can lid, causing work hardening and constriction. As a result, even when the can lid is formed from a thin plate, the pressure resistance of the can lid can be maintained, and
The occurrence of cracks in the inner coating can be prevented. Moreover, the shuffle property of the can lid can be maintained.

According to a third aspect of the present invention, in addition to the first or second aspect, an inner wall of the reinforcing annular groove is substantially parallel to a center axis of the panel portion. Is what you do.

According to the third aspect of the present invention, since the inner wall of the reinforced annular groove is substantially parallel to the central axis of the panel portion, the strength of the inner wall and the outer wall of the reinforced annular groove is improved. . As a result, even if a can lid is formed from a thin plate material, a can lid excellent in pressure resistance can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. A can lid for a positive internal pressure can (hereinafter simply referred to as a can lid) 1 shown here is made of a flat plate (not shown) made of an aluminum alloy. It is formed using a known molding die. Note that an inner surface coating (not shown) made of a synthetic resin is previously formed on one surface of the flat plate. This inner surface coating is formed from a protective coating or a resin film. Examples of the paint include any protective paint composed of a thermosetting and thermoplastic resin, for example, a modified epoxy paint such as a phenol-epoxy paint and an amino-epoxy paint, a vinyl chloride-vinyl acetate copolymer, and an epoxyphenol-modified-vinyl paint. Or a combination of two or more vinyl or modified vinyl paints. Further, as the resin film, for example, polyethylene terephthalate (PET) has a basic constitution, and a copolymer such as polyethylene isophthalate (PEIT) can be applied. Also, 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 coating, even if it depends on the contents of the can.
If it exceeds 5 μm, the material used for the inner surface coating becomes excessive, which is not preferable.

At the center of the can lid 1, a disk-shaped panel portion 2 is formed. Further, on the outer periphery of the panel portion 2, there is formed a reinforced annular groove 3 which is U-shaped and substantially concave downward in FIG. 1, and is formed by an inner side wall 3a, a bottom wall 3b, and an outer side wall 3c. . In addition, the bottom wall 3b
And the outer wall 3c are connected so as to form a curved surface having a constant radius of curvature r. The outer wall 3c is formed so as to extend in a direction forming an angle θ1 from a direction along the central axis of the panel portion 2. The angle θ1 is not less than 2 ° and not more than 10 °. Note that the angle θ1 is 2
The reason why the angle is not less than 2 ° is that if the angle is less than 2 °, the pressure resistance and the shuffling property when a plurality of can lids 1 are stacked may be reduced. For example, the angle θ1 is 0 °, that is, the outer wall 3 is in the same direction as the direction along the central axis of the panel portion 2.
When c is extended, the shuffle value (the length s represented by FIG. 4) becomes smaller than 1.0 mm, and the shuffle property decreases. Further, when the can lid 1 is used 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 in the direction along the center axis of the panel portion 2, that is, in the vertical direction in FIG. It is desirable to form the can cover 1 so as to increase the pressure resistance of the can lid 1.

A curved connecting wall 4 extends substantially upward from the outer wall 3c of the reinforcing annular groove 3 in FIG. The curved connecting wall 4 has a curved shape having a constant radius of curvature R, and the center of the radius of curvature is located on the side opposite to the panel portion 2. That is, the curved surface connecting wall 4 is formed so as to bulge and protrude toward the panel portion 2 side. Then, as shown in FIG.
Are stacked in the same direction, the curved connecting wall 4 of a certain can lid 1
A curved connecting wall 4 is formed so that the outer surface of the reinforcing annular groove 3 of the can lid 1 adjacent to the surface on the side of the panel portion 2 (the surface that becomes the outer surface of the can) can contact the surface.

Further, a tapered chuck wall 5 is formed extending from the curved surface connecting wall 4 substantially upward in FIG.
The chuck wall 5 is formed so as to extend in a direction forming an angle θ2 from a direction along the central axis of the panel portion 2. The angle θ2 is larger than the above-described angle θ1 and is not less than 10 ° and not more than 20 °. This means that if the angle θ2 is less than 10 °, when the can lid 1 is wound around a cylindrical can body (not shown), it becomes difficult to insert the chuck tool, and the fitting with the chuck is difficult. It becomes loose and poor sealing easily occurs during double winding. On the other hand, when the angle θ2 exceeds 20 °, the shuffling property is reduced while the reinforced annular groove 3 is maintained. On the other hand, in the state where the shuffle property is maintained, the diameter of the reinforcing annular groove 3 in the radial direction of the can lid 1 has to be reduced, and the diameter of the panel decreases accordingly. In the case of an easy-open can lid such as a stay-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 is farther than the tightening portion, thereby consuming. When the person tilts the can body and drinks the contents from the opening of the can lid 1, there is a disadvantage that the drink becomes difficult to drink.

The reason why the angle θ2 is made larger than the angle θ1 is that if the angle θ2 is equal to or smaller than the angle θ1, the curved surface connecting wall 4 swells and protrudes to the opposite side to the panel portion 2. This is because the pressure resistance of the can lid 1 may be reduced.

Further, from the upper end of the chuck wall 5, FIG.
A trumpet-shaped shoulder wall 6 extending substantially upward in FIG. A flange / curl portion 7 is formed extending from the shoulder wall 6 to the left in FIG. The flange / curl portion 7 includes the can lid 1
Is formed by curling the edges of the. The length T (curl thickness) between the upper end and the lower end of the flange / curl portion 7 in the direction along the center axis of the panel portion 2 is 2.0 mm or more and 2.3 mm or less. The flange / curl portion 7 is wound around an opening edge of a cylindrical can body (not shown), so that the can lid 1 is fixed to the can body, and a positive internal pressure can (not shown).
Is formed.

The thickness of the can lid 1 is not less than 0.220 mm and not more than 0.335 mm. This means that the plate thickness is 0.
If it is 220 mm or less, the pressure resistance of the can lid 1 is reduced.
Radius of curvature r of the portion connecting bottom wall 3b and outer wall 3c
Needs to be 0.35 mm or less. In this case, in the process of forming the can lid 1, the neck 1 may be constricted, and the bottom wall 3b may be cracked. On the other hand, when the plate thickness is 0.
If it is 335 mm or more, the material used for the can lid 1 becomes excessive, and it is not economical.

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 portion 2 is represented by t as the thickness of the panel portion 2 and k as the stack thickness. Then, it is more than (r + t) and less than (k + r + t). This is because if h1 is too small,
When the chuck wall 5 is formed with a common tangent line L (the bottom of the reinforced annular groove 3) by using a conventionally known mold for forming a can lid (for example, one described in JP-A-60-170540). When the curved connecting wall 4 is formed so as to bulge and protrude toward the panel portion 2, constriction occurs in the can lid 1 in order to approach the portion connecting the wall 3 b and the outer peripheral wall 3 c and a common tangent to the shoulder wall 6. And may damage its inner coating. On the other hand, if h1 is too large,
The position where the curved surface connecting wall 4 protrudes toward the panel portion 2 is located above in FIG. 1, and there is a possibility that the strength of the can lid 1 cannot be improved. Furthermore, the length of the chuck wall 5 in the direction along the central axis of the panel portion 2 must be reduced, and when the can lid 1 is wound around the can body, there is a possibility that normal winding cannot be obtained. There is a possibility that the airtightness of the formed can is impaired.

Further, the above-mentioned curved surface connecting wall 4 is formed such that its radius of curvature R is 0.66 mm or more and 9.00 mm or less. This is for the following reason. When the radius of curvature R of the curved surface connecting wall 4 is less than 0.66 mm, the curved surface connecting wall 4 may be constricted when the curved surface connecting wall 4 is formed. When the constriction occurs, there is a possibility that a crack may be generated in the inner coating covering the curved surface connecting wall 4 where the constriction has occurred. Also,
When the radius of curvature R of the curved surface connecting wall 4 exceeds 9.00 mm, the protruding length protruding toward the panel portion 2 becomes small,
In addition, since the projecting position is located above in FIG. 1, it is insufficient to improve the strength of the can lid 1.

The maximum distance from the common tangent line L to the projection of the curved connecting wall 4 is at least 10% and 50% of the plate thickness of the can lid 1.
The curved connecting wall 4 is formed as follows. If this 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 placed between the can lid 1 and the can lid 1. Not only is it not easily inserted, but also the flange and curl 7 of the can lid 1 may be deformed or damaged by the separator knife. Further, when the can lids 1 are conveyed, once the can lids 1 overlap each other, the can lids 1 are closely fitted to each other, so that the can lids 1 do not easily follow the guide of the chute, causing a blocking phenomenon to occur, and There is a possibility that the can lid 1 is clogged and the productivity is reduced.

Further, the length (counter sink depth) h2 from the upper surface of the reinforcing annular groove 3 to the upper end surface of the flange curl portion 7 in the direction along the central axis of the panel portion 2 is 6.0 mm. The length (panel height) h between the upper surface of the panel portion 2 and the bottom wall 3b of the reinforcing annular groove 3 in the direction along the central axis of the panel portion 2 is set to 7.1 mm or less.
3 can be 1.1 mm or more and 2.4 mm or less.
Are formed. In addition, when it is adopted for a can lid of a can body in which carbonated beverages such as cola and beer are enclosed, h3
Is set relatively long, and it is desirable to increase the pressure resistance of the can lid 1.

Next, an experiment for demonstrating the effect of the can 1 for a positive internal pressure can, which is one embodiment of the present invention, will be described. First, a plurality of can lids 1 using 5182 series aluminum as the material aluminum were prepared, and the following three items were measured.

First, as a first measurement item, the pressure resistance of the can lid 1 was measured. First, after the can lid 1 is squeezed and wound around an iron can body, the can bottom side of the can body is opened, and gas pressure is applied to the inside of the can body by a pressure resistance inspection device, and a part of the reinforcing annular groove 3 of the can lid 1 is formed. The pressure when the first squaring (buckling) occurred from was measured by a recorder.

As a second measurement item, the surface (the lower surface in FIG. 1) which is the inner surface of the can lid 1 is turned upward, and the flange / curl portion 7 of the can lid 1 is turned up as shown in FIG. A plurality of can lids 1 are laminated until the total thickness becomes about 50.8 mm, and the can lids 1 are sequentially shifted sideways from the lower can lid 1 and the shuffle value (side shift amount) s is measured with a shuffle gauge or a vernier caliper. It was measured.

Further, as a third measurement item, copper sulfate was dissolved in acetone, the can lid 1 was immersed in the solution for 10 minutes, then washed with water, and the inner coating film located in the reinforced annular groove 3 was observed by a stereoscopic microscope. Was measured for corrosion state. And
When the corroded point is a point and up to five points are generated, the can lid 1 is allowed, and the corrosion point is six or more points or not the point but the corrosion is generated over the surface. In that case, the can lid 1 was determined to be unacceptable.

[0033]

Embodiment 1 First, two types of can lids are prepared as the can lid 1 of the present invention. The can lids A and B are made of a 5182-H39 aluminum alloy, have a plate thickness of 0.235 mm, and have a phenol-epoxy paint applied at 110 mg / dm2 on the inner surface of the can and baked and cured. The outer diameters of the flange and curl portions of the can lids A and B are 57.2.
0 mm (lid designation 200), the length h2 from the upper surface of the bottom wall 3b of the reinforcing annular groove 3 to the upper end surface of the flange curl portion 7 is 6.05 mm, and the bottom wall 3b and the outer wall 3c of the reinforcing annular groove The radius of curvature r of the portion connecting the first and second surfaces is 0.66 mm, the radius of curvature R of the curved surface connecting wall 4 is 0.66 mm, the radius of curvature of the shoulder wall 6 is 2.00 mm, and the panel height h3 is 1.
3 mm, length T between upper and lower ends of 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 °, a length h1 of 1.3 mm, and a ratio of the maximum protruding length of the curved connecting wall 4 to the plate thickness of 38.7. %It has become. The can lid B has an angle θ1 of 6.5 ° and an angle θ2 of 15.0.
°, the length h1 is 1.0 mm, and the ratio of the maximum protruding length of the curved surface connecting wall 4 to the plate thickness is 16.6%.

Nine types of can lids are prepared as can lids of comparative examples. The can lids a, b,..., I have the same shape as the can lid A, which is the positive internal pressure can can lid 1 of 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 reinforcing annular groove extends in the thickness direction of the panel portion. Further, the can lid b has an inclination angle θ2 of the chuck wall of 1
It is set to 4.4 °, and the projecting length of the curved surface connecting wall is set to 0. Further, the can lid c has a radius of curvature R of the curved surface connecting wall.
Is set to 10.00 mm. Then, 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. Have been.

The can lid f is formed by projecting the outer wall of the reinforced annular groove to the side opposite to the panel portion so that the angle θ2 of the chuck wall is 9.0 ° and θ1 is larger than θ2. Have been. Further, the can lid g has an angle θ of the chuck wall.
2 is set to 22.5 °, and a curved connecting wall is formed so that a defect does not occur in the inner surface coating. And can lid h
Is formed by setting the length h1 from the bottom surface of the bottom wall of the reinforced annular groove to the upper end of the outer wall to 3.2 mm, and forming a curved connecting wall so that a defect does not occur in the inner surface coating. 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 thickness direction of the panel portion.

The above-mentioned can lids A and B and can lids a, b,.
The above three items were measured for i. Table 1 shows the results.

[0037]

[Table 1] As can be seen from Table 1, the can lids a, b,.
It can be seen that at least one of the pressure resistance and the shuffle value of the can lid cannot satisfy the desired value. Further, it can be seen that there is a can lid in which the defect of the inner surface coating is determined to be impossible. On the other hand, in the can lids A and B which are the examples of the present invention, both satisfy the desired values of the pressure resistance and the shuffle value of the can lid, and it is determined that the defect of the inner surface coating is acceptable. Understand.

[0038]

Embodiment 2 On the other hand, four types of can lids are prepared as the can lid 1 of the present invention. Those can lids C, D, E and F are 518
It is made of 2-H38 aluminum alloy and has a thickness of 0.26.
mm, and a vinyl chloride organosol paint is applied at 140 mg / dm2 on the surface serving as the inner surface of the can, and is baked and cured. The outer diameters of the flange and curl portions of the can lids C, D, E and F are 64.65 mm (lid designation 206).
The length h2 from the upper surface of the bottom wall 3b of the reinforcing annular groove 3 to the upper end surface of the flange curl portion 7 is 6.90 mm, and the radius of curvature r of the portion connecting the bottom wall 3b and the outer wall 3c of the reinforcing annular groove is r.
Is 0.35 mm, and the radius of curvature of the shoulder wall 6 is 1.80.
mm, the panel bite 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. Further, the can lid C has a curvature radius R of the curved surface connecting wall 4 of 7.00 mm, an angle θ1 of 6.5 °, and an angle θ.
2 is 13.5 °, the length h1 is 1.8 mm, and the ratio of the maximum protruding length of the curved surface connecting wall 4 to the plate thickness is 46.5%.
It has become. In the can lid D, the radius of curvature R of the curved surface connecting wall 4 is 3.50 mm, the angle θ1 is 7.5 °, and the angle θ2 is 1
3.5 °, length h1 is 2.2 mm, and curved surface connecting wall 4
The ratio of the maximum protruding length to the plate thickness is 45.4%. Further, in the can lid E, the curvature radius R of the curved surface connecting wall 4 is 0.66 mm, the angle θ1 is 8.5 °, and the angle θ2 is 13.
0 °, the length h1 is 2.5 mm, and the ratio of the maximum protruding length of the curved surface connecting wall 4 to the plate thickness is 37.3%. The can lid F has a curvature radius R of the curved connecting wall 4 of 7.0.
0 mm, the angle θ1 is 5.0 °, the angle θ2 is 13.5 °,
The length h1 is 1.3 mm, and the ratio of the maximum protruding length of the curved surface connecting wall 4 to the plate thickness is 50.0%.

Nine types of can lids are prepared as can lids of comparative examples. The 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 such 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. The can lid k has a chuck wall inclination angle θ2 of 11.2 °,
The projecting length of the curved surface connecting wall is set to 0. Further, the can lid 1 has a curvature radius R of the curved surface connecting wall of 10.00 m.
m. Then, the can lid m and the can lid n 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. Have been.

The can lid o is formed by projecting the outer wall of the reinforced annular groove to the side opposite to the panel so that the angle θ2 of the chuck wall is 9.0 ° and θ1 is larger than θ2. Have been. Further, the can lid p has an outer wall angle θ1 of 0.0 ° and a chuck wall angle θ2 of 2 °.
The angle is set to 2.5 °, and the outer wall of the reinforcing annular groove is formed to extend in the thickness direction of the panel portion. And can lid q
Is formed by setting the length h1 from the bottom surface of the bottom wall of the reinforced annular groove to the upper end of the outer wall to 3.5 mm, and forming a curved connecting wall so that a defect does not occur in the inner surface coating. 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 substantially extends in the thickness direction of the panel portion.

The above-mentioned can lids C, D, E, F, and can lids j,
The above three items were measured for k,..., and r. Table 2 shows the results.

[0042]

[Table 2] As can be seen from Table 2, the can lids j, k,.
It can be seen that, in the can lids other than the can lid n, the pressure resistance of the can lid cannot satisfy the desired value and the shuffle value of the can lid n cannot satisfy the desired value. Further, it can be seen that there is a can lid in which the defect of the inner surface coating is determined to be impossible. On the other hand, in the can lids C, D, E, and F according to the embodiments of the present invention, all satisfy the desired values of the pressure resistance and the shuffle value of the can lid, and it is determined that the defect of the inner surface coating is acceptable. You can see that it is.

[0043]

As described above, according to the first aspect of the invention, 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.
By being equal to or less than 00 mm, constriction does not occur in the can lid, and even if the can lid is formed from a thin plate material, it is possible to obtain a can lid having excellent pressure resistance strength, and to prevent the inner coating from cracking. Can be prevented.

Further, the outer wall and the curved connecting wall of the reinforced annular groove are continuous with each other in the 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 move to the outer peripheral side. Therefore, the inclination angle is gradually increased, and the contact points between the can lids are present at the increased locations, so that the shuffling property of the can lid can be improved while the pressure resistance of the can lid is improved. Therefore, troubles such as deformation of the flange / curl portion in the operation of supplying the can lid to the seamer can be eliminated, and when the can lids are transported by the chute in a stacked state, the can lid blocks in the chute. This can prevent the clogging of the lid in the chute and the damage to the inner surface coating.

According to the second aspect of the invention, the outer wall of the reinforced annular groove extends in a direction of 2 ° or more and 10 ° or less with respect to the center axis of the panel portion. Even when the depth of the groove is increased, a draft angle can be secured in the mold, and constriction can be prevented. If the clearance of the mold for forming a can lid is smaller than the plate thickness, the mold bites into the can lid, causing work hardening and constriction. As a result, even when the can lid is formed from a thin plate material, the pressure resistance of the can lid can be maintained, and the occurrence of cracks in the inner surface coating can be prevented. Moreover, the shuffle property of the can lid can be maintained.

Further, according to the third aspect of the present invention, since the inner wall of the reinforced annular groove and the central axis of the panel portion are substantially parallel, the strength of the inner wall and the outer wall of the reinforced annular groove is improved. As a result, even if a can lid is formed from a thin plate material, a can lid excellent in pressure resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a can lid according to the present invention.

FIG. 2 is a sectional view showing a state in which the can lids of the present invention are stacked.

FIG. 3 is a partial cross-sectional view showing an example of the 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]

1 ... can lid, 2 ... panel part, 3 ... reinforced annular groove, 4 ...
Curved surface connecting wall, 5: chuck wall, 6: shoulder wall,
7 ... Flange curl part.

Claims (3)

[Claims] A reinforced annular groove having a U-shaped cross section depressed in a thickness direction of the panel portion is formed on an outer periphery of a substantially disk-shaped panel portion, and an inner wall of the reinforced annular groove is formed on the panel portion. And the bottom wall of the reinforcing annular groove continuously extends radially outward of the panel portion on the outer peripheral side of the inner wall of the inner wall, and further, the outer periphery of the bottom wall. The outer wall of the reinforcing annular groove extends continuously so as to face the inner wall in the radial direction of the panel portion, and is cut along the center axis direction of the panel portion on the outer peripheral side of the outer wall. A curved connecting wall having a curved cross-section is continuous so as to extend in the thickness direction of the panel portion, and a tapered cylindrical chuck wall is continuously formed on the outer peripheral side of the curved connecting wall, A trumpet-shaped shoulder wall continues on the outer peripheral side of the chuck wall, and A can cover for a positive internal pressure can, in which a flange curl portion is formed continuously on the outer peripheral side of the shoulder wall in the radial direction of the panel portion and has an outer peripheral end bent inward in the radial direction. In the above, the angle between the chuck wall and the central axis of the panel portion is 10 ° or more and 20 ° or less, and the curved surface connecting wall has a shape that is convex toward the panel portion side and has a curvature of the convex portion. 0.66mm radius
Not less than 9.00 mm, and connects the inner curvature circle of the outer peripheral bottom wall of the reinforcing annular groove connected to the curved connection wall and the outer curvature circle of the shoulder wall connected to the curved connection wall. The maximum distance from the common tangent to the protrusion of the curved connecting wall is one of the thickness of the panel portion.
0% or more and 50% or less, and when they are shifted in the radial direction in a state where they are stacked in the same orientation,
A can lid for a positive internal pressure can, wherein one curved surface connecting wall and the bottom wall of the other reinforced annular groove are formed so as to contact with each other. 2. The positive hole according to claim 1, wherein an angle formed between an outer wall of the reinforcing annular groove and a center axis of the panel portion is 2 ° or more and 10 ° or less. Can lid for internal pressure can. 3. The can lid for a positive internal pressure can according to claim 1, wherein an inner wall of the reinforced annular groove is substantially parallel to a center axis of the panel portion.