JP2021084636A - Bottle can and manufacturing method thereof - Google Patents

Abstract

To prevent deformation such as buckling during capping.SOLUTION: A bottle can includes: a cylindrical barrel portion having an outer diameter of between 64.25 mm and 68.24 mm; a diameter reduction portion a diameter of which reduces from an upper end of the cylindrical barrel portion; a tapered cylindrical portion which is connected to an upper end of the diameter reduction portion and a diameter of which gradually reduces as going upward in a can axis direction; a neck portion a diameter of which further reduces at an upper end of the tapered cylindrical portion; and a mouse portion having an outer diameter between 36.0 mm and 40.0 mm of a swelling portion where a cap material is caught. The diameter reduction portion includes a convex-shaped bending portion connected to the upper end of the cylindrical barrel portion, and a recess-shaped bending portion formed at a lower end of the tapered cylindrical portion. An inclination angle of an outer surface of the tapered cylindrical portion against the can axis is between 5° and 10°, and on a vertical section surface through the can axis, a curvature radius of an outer surface of the recess-shaped bending portion is between 6.0 mm and 17.0 mm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bottle can in which a metal cap is attached to an opening and is filled with contents such as a beverage, and a method for producing the same.

As a container filled with contents such as beverages, a container is known in which a metal cap is attached to the opening of a bottle-shaped can (bottle can) to seal the container. In general, this bottle can is provided with a reduced diameter portion that gradually reduces in diameter toward the upper side on the opening side of a cylindrical body portion having a bottom, and a mouth portion is provided on the reduced diameter portion via a neck portion. It is said that it has a structure. Such bottle cans are subjected to a cupping process in which a metal plate material (aluminum alloy material plate material) is drawn to form a cup, and a DI (Drawing & Ironing) process in which the cup is re-squeezed and ironed. , A bottomed cylindrical cylinder is formed, and a reduced diameter portion is formed by performing a diameter reduction process on the opening side of the body of the bottomed cylindrical cylinder, and then a bulging portion and a threaded portion are formed. , A mouth portion having a curl portion or the like is formed.

A metal cap is attached to the mouth of this bottle can. Before being attached to the bottle can, this cap has a disk-shaped top plate portion and a peripheral wall portion extending vertically from the outer peripheral edge thereof, and after being put on the mouth portion of the bottle can, the bottle can The peripheral wall portion is processed along the threaded portion, and the lower end portion of the peripheral wall portion is locked to the bulging portion. When opening the package, when the cap is rotated, the bridge portion formed on the peripheral wall portion is cut, so that the peripheral wall portion is separated into upper and lower parts and can be removed from the mouth portion.
At the time of such capping, a large load acts in the can axis direction of the bottle can, so the bottle can must have a strength capable of withstanding the load.

In Patent Document 1, by forming a concave portion that curves inward in the radial direction or a convex portion that curves outward in the radial direction from the lower end of the mouth portion to the upper end of the reduced diameter portion, deformation due to a load during capping is prevented from occurring. ing.
In Patent Document 2, the deformation strength is enhanced by forming an S-shaped bead portion and a straight portion having a constant outer diameter in order from the bulging portion side between the bulging portion and the reduced diameter portion. There is.
In Patent Document 3, the deformation strength is increased by performing a reform process to reduce the radius of curvature of the R portion of the connection between the reduced diameter portion and the mouth portion during the necking step of forming the reduced diameter portion and the mouth portion in the bottle can. ing.

Japanese Unexamined Patent Publication No. 2001-21316 Japanese Unexamined Patent Publication No. 2018-140827 Japanese Unexamined Patent Publication No. 2018-177250

By the way, there is a demand for increasing the size of bottle cans in order to increase the capacity. The capacity of the bottle can can be increased by lengthening the body, but it is also conceivable to extend the reduced diameter portion between the bottle and the mouth to increase the capacity near the reduced diameter portion.
However, if the reduced diameter portion is extended, there is a risk of buckling due to the load during capping.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent deformation such as buckling during capping or the like.

The bottle can of the present invention is connected to a cylindrical body having an outer diameter of 64.25 mm or more and 68.24 mm or less, a reduced diameter portion that is reduced in diameter from the upper end of the cylindrical body portion, and an upper end of the reduced diameter portion. A tapered cylinder that gradually shrinks in diameter toward the upper end in the can axis direction, a neck that is further reduced in diameter at the upper end of the tapered cylinder, and a bulge that is formed at the upper end of the neck and the cap material is involved. A mouth portion having an outer diameter of 36.0 mm or more and 40.0 mm or less is provided, and the reduced diameter portion is a convex curved portion connected to the upper end of the cylindrical body portion and a lower end portion of the tapered cylinder portion. A bottle can having a concave curved portion formed between them.
The inclination angle of the outer surface of the tapered cylinder portion with respect to the can shaft is 5 ° or more and 10 ° or less.
In the vertical cross section passing through the can shaft, the radius of curvature of the outer surface of the concave curved portion is 6.0 mm or more and 17.0 mm or less.

Since this bottle can has a shape in which a convex curved portion, a concave curved portion, and a tapered tubular portion are continuously formed between the cylindrical body and the neck, the tapered tubular portion is used to form the cylindrical body to the mouth. Can be increased in length. In addition, the lower part of the neck portion is reinforced, and the radius of curvature of the concave curved portion between the convex curved portion and the tapered tubular portion is small, thereby increasing the column strength in the can axis direction and during capping, etc. It is possible to prevent deformation at the time of.
In this case, if the radius of curvature of the outer surface of the concave curved portion is less than 6.0 mm, the radius of curvature becomes too small, which may cause buckling, and the curved surface may not be smooth and the design may be impaired. On the other hand, if it exceeds 17.0 mm, the column strength decreases.
If the inclination angle of the outer surface of the tapered cylinder portion with respect to the can shaft is less than 5 °, molding is difficult, and if it exceeds 10 °, it is difficult to secure a desired can height. Further, this angle range is preferable in order to smoothly connect the tapered cylinder portion having a small inclination angle and the reduced diameter portion having a larger inclination angle to improve the design.

In the bottle can of the present invention, the bottle can has a second convex curved portion having a convex outer surface between the convex curved portion and the concave curved portion, and the radius of curvature of the outer surface of the second convex curved portion is 20 mm. It is preferably 40 mm or more and 40 mm or less.

If the radius of curvature of the second convex curved portion is less than 20, the connection portion with the concave curved portion looks stepped, which may spoil the appearance of the bottle can. It is difficult to form a shape.
The convex curved portion and the second convex curved portion may be in a directly connected state, or may be connected by a linear or near-straight curved tapered portion in the vertical cross section.

The method for manufacturing a bottle can of the present invention includes a cylindrical body having an outer diameter of 64.25 mm or more and 68.24 mm or less, a reduced diameter portion that is reduced in diameter from the upper end of the cylindrical body portion, and an upper end of the reduced diameter portion. A tapered cylinder portion that is connected to and gradually reduces in diameter toward the upper side in the can axis direction, a neck portion that is further reduced in diameter at the upper end of the tapered cylinder portion, and a cap material that is formed at the upper end of the neck portion and is involved. The bulging portion is provided with a mouth portion having an outer diameter of 36.0 mm or more and 40.0 mm or less, and the reduced diameter portion is a convex curved portion continuous with the upper end of the cylindrical body portion and a tapered tubular portion. A method for manufacturing a bottle can having a concave curved portion formed between the lower ends.
A cylinder forming step of forming a cylinder having the same outer diameter as the cylindrical body,
While pushing the necking die from the upper end of the cylinder in the can axis direction, the upper part of the cylinder is reduced in diameter to form the convex curved portion continuous with the upper end of the cylindrical body and above the convex curved portion. A diameter reduction step of forming a curved recess having a concave outer surface and the tapered cylinder portion continuous with the upper end of the curved recess.
After the diameter reduction step, the curved recess is reformed to form the concave curved portion having a radius of curvature smaller than that of the curved recess.

In the manufacturing method of the present invention, a convex curved portion, a curved concave portion, and a tapered tubular portion are first formed on the cylindrical body portion. Next, by the reforming step, a concave curved portion having a reduced radius of curvature on the outer surface of the curved concave portion is formed to increase the rigidity in the vicinity of the concave curved portion.

In the method for manufacturing a bottle can, in the reforming step, when the concave curved portion is formed, it is preferable to form a second convex curved portion between the concave curved portion and the convex curved portion.

Since the second convex curved portion is further formed between the convex curved portion and the concave curved portion, the vicinity of the concave curved portion is further reinforced and the column strength is enhanced.

In the method for manufacturing a bottle can, a bent convex portion protruding outward in the radial direction is formed at the upper end of the tapered cylinder portion, and a bent concave portion continuous from the upper end of the bent convex portion is formed at the lower end of the neck portion. It is preferable to have a neck lower portion forming step in which the bent convex portion and the bent concave portion are deformed to reduce the radius of curvature of the bent convex portion and the bent concave portion after the reform step.

Since the tapered cylinder portion has a small inclination angle with respect to the can shaft, the processing allowance is small, and it becomes extremely difficult to evenly apply strain in the circumferential direction.
Therefore, after the diameter reduction step, the tapered tubular portion is shaped by a reforming step, but in the portion extending from the tapered tubular portion to the neck portion, the radius of curvature of the bent convex portion and the bent concave portion is reduced in the neck lower portion forming step. Since the processing is performed, springback and the like can be suppressed, these can be reliably formed, and the deformation strength can be increased.

According to the present invention, deformation such as buckling during capping can be prevented.

It is a front view which made the half of the bottle can which concerns on one Embodiment of this invention a cross section. It is an enlarged view of the main part of the bottle can of FIG. It is a flowchart which shows the main process of the manufacturing method of a bottle can. It is a process diagram which shows a part of the manufacturing process of a bottle can in the order of (a)-(c). It is sectional drawing which shows the state which arranged the 1st necking die in the cylinder body in the 1st diameter reduction step. It is sectional drawing which showed the molded part of each necking die used in the 1st diameter reduction step by superimposing. It is a front view which shows the main part of the 1st intermediate molded body formed by the 1st diameter reduction step. It is a front view which shows the main part of the 2nd intermediate molded body after a remodeling process. It is sectional drawing which shows the state which is molding by the molding die in the neck lower part forming step.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view of a bottle can according to an embodiment of the present invention. The bottle can 1 is used as a container for accommodating beverages and the like by attaching a cap (not shown) to the open end 1a.

The bottle can 1 is made of a thin metal such as aluminum or an aluminum alloy, and as shown in FIG. 1, a cylindrical body portion 12 having a bottom portion 11 and a diameter-reduced portion 13 whose diameter is reduced from the upper end of the cylindrical body portion 12 , A tapered cylinder portion 14 connected to the upper end of the reduced diameter portion 13 and gradually reduced in diameter toward the upper side in the can axis direction, a small diameter neck portion 15 further reduced in diameter at the upper end of the tapered cylinder portion 14, and a neck portion. It is provided with a mouth portion 16 having a diameter of 38 mm formed at the upper end of the fifteen. The reduced diameter portion 13 is a first convex curved portion (simply referred to as a convex curved portion in the present invention) 131 having a convex outer surface from the upper end of the cylindrical body portion 12, and a first convex curved portion 131. It has a second convex curved portion 133 formed upward, and a concave curved portion 132 having a concave outer surface from the upper end of the second convex curved portion 133 to the lower end of the mouth portion 16.
As shown in FIG. 1, the cylindrical body portion 12, the diameter reduction portion 13, the tapered cylinder portion 14, the neck portion 15, and the mouth portion 16 are arranged coaxially with each other, and in the present embodiment, these common axes can be used. The explanation will be given by referring to the axis S.

The cylindrical body portion 12 has a nominal outer diameter of 211, and is formed to have an outer diameter D1 of 64.25 mm or more and 68.24 mm or less. A dome-shaped bottom portion 11 is formed at the lower end of the cylindrical body portion 12, and the bottom portion 11 is located on the can shaft S and bulges upward (inside the cylindrical body portion 11). It includes a dome portion 111 formed so as to protrude, and a heel portion 112 that connects the outer peripheral edge portion of the dome portion 111 and the lower end portion of the cylindrical body portion 12. Further, the connecting portion between the dome portion 111 and the heel portion 112 is bent so as to be convex downward in the can axis S direction, and the bottle can 1 is in an upright posture (the mouth shown in FIG. 1). The ground contact portion 113 is in contact with the mounting surface when it is mounted on the mounting surface so that the portion 16 faces upward). The ground contact portion 113 projects downward at the bottom portion 11 and forms an annular shape extending along the circumferential direction. The diameter D2 of the ground contact portion 113 is formed to be, for example, 56 mm.

The reduced diameter portion 13 has a first convex curved portion 131 formed on the lower side in the can axis S direction and a concave curved portion 132 formed on the upper side, and the second convex curved portion 133 is connected between them. The shape is such that the diameter decreases toward the upper side in the can axis direction. In this case, the first convex curved portion 131 and the second convex curved portion 133 are connected by the tapered portion 134, and the space between the first convex curved portion 131 and the second convex curved portion 133 is connected. It is formed in a convex shape as a whole. The radius of curvature R1 of the outer surface of the first convex curved portion 131 is formed to be 20 mm or more and 30 mm or less, and the radius of curvature R2 of the outer surface of the second convex curved portion 133 is formed to be 20 mm or more and 40 mm or less. Further, in the vertical cross section passing through the can shaft, the inclination angle θ1 of the outer surface of the tapered portion 134 with respect to the can shaft is set to 30 ° or more and 45 ° or less. The first convex curved portion 131 and the second convex curved portion 133 may be directly connected to each other. Further, the tapered portion 134 may also have a linear shape in a vertical cross section passing through the can shaft S, or may have a curved shape having a large radius of curvature and a substantially straight line.

On the other hand, the radius of curvature R3 of the outer surface of the concave curved portion 132 is 6.0 mm or more and 17.0 mm or less, and the tapered tubular portion 14 has an inclination angle of the outer surface with respect to the can shaft S of 5 ° or more in the vertical cross section passing through the can shaft S. It is 10 ° or less. In this case, if the radius of curvature R3 of the outer surface of the concave curved portion 132 is less than 6.0 mm, the radius of curvature becomes too small, which may cause buckling, and the curved surface may not be smooth and the design may be impaired. On the other hand, if it exceeds 17.0 mm, the column strength decreases. Further, if the inclination angle θ2 of the outer surface of the tapered cylinder portion 14 with respect to the can shaft S is less than 5 °, molding is difficult, and if it exceeds 10 °, it is difficult to secure a desired can height. Further, this angle range is preferable in order to smoothly connect the tapered cylinder portion 14 having a small inclination angle and the diameter-reduced portion 13 having a larger inclination angle to improve the design. The tapered cylinder portion 14 is formed in a straight line in a vertical cross section passing through the can shaft S, but may have a curved shape having a large radius of curvature and a substantially straight line.

A bent convex portion 141 protruding outward in the radial direction is formed at the upper end of the tapered tubular portion 14, and a bent concave portion 151 connected to the upper end of the bent convex portion 141 is provided at the lower end of the neck portion 15. There is. The bent convex portion 141 and the bent concave portion 151 form a stepped shape from the tapered tubular portion 14 to the neck portion 15.
The neck portion 15 has the smallest diameter, and the diameter of the neck portion 15 is expanded at the upper end portion to connect the mouth portion 16. Therefore, the neck portion 15 is formed in a constricted shape between the tapered cylinder portion 14 and the mouth portion 16.

In the mouth portion 16, a bulging portion 161 is formed in the circumferential direction on the neck portion 15 described above, a male screw portion 162 is formed on the bulging portion 161, and a curl is formed on the opening end portion 1a above the male screw portion 162. Part 163 is formed. Then, the cap material having the top plate portion and the peripheral wall portion is put on the mouth portion 16, formed along the male screw portion 162, and the hem portion of the cap material is wound around the bulging portion 161 of the cap material. When the liner on the inner surface is pressed against the curl portion 163, the inside of the bottle can 1 is sealed by the cap.

In the present embodiment, the overall height of the bottle can 1 (height from the bottom surface of the ground contact portion 113 of the bottle can 1 to the upper surface of the curl portion 143) H0 is 180 mm or more and 230 mm or less, and the cylindrical body portion 12 and the reduced diameter portion 13 The length H1 in the can axis S direction from the connection position with the lower convex curved portion 131 to the upper end of the mouth portion 16 is 60 mm or more and 80 mm or less, and the lower side of the cylindrical body portion 12 and the reduced diameter portion 13. The length H2 in the can axis S direction from the connection position with the convex curved portion 131 to the upper end of the bent convex portion 141 of the tapered cylinder portion 14 is formed to be 42 mm or more and 62 mm or less. As for the content, it can be used as a beverage can of 400 ml or more and 600 ml or less.

FIG. 3 is a flowchart showing a manufacturing method of the bottle can 1 thus formed.
In order to manufacture this bottle can 1, first, a plate material of a thin metal such as an aluminum alloy is punched and drawn to form a relatively large diameter and shallow cup 21 shown in FIG. 4 (a) (copping step). After that, the cup 21 is subjected to drawing and ironing (DI (Drawing & Ironing)) again to form a bottomed cylindrical cylinder 22 having a predetermined height as shown in FIG. 4 (b). Then, the upper end is trimmed and trimmed (cylinder forming step). By this cylinder forming step, the bottom of the cylinder 22 is formed into the shape of the bottom 11 as the final bottle can 1, and the body of the cylinder 22 has the same outer diameter as the cylindrical body 12 of the final bottle can 1. Is formed in.

After forming the tubular body 22, as shown in FIG. 4C, the upper portion of the tubular body 22 is reduced in diameter to the upper end of the cylindrical body portion 12, and the first convex curved portion 131, in this order from the bottom. A diameter reduction step of forming a curved recess 42, a tapered cylinder portion 14, a bending convex portion 141, and a bending recess 151, and after the diameter reduction step, the curved recess 42 is deformed to form a concave curved portion 132, and the concave curved portion 132 is formed. A reforming step of forming a second convex curved portion 133 and a tapered portion 134 between the first convex curved portion 131 and a tapered portion 134 to form a diameter-reduced portion 13 in which these are continuous, and a tapered tubular portion 14 The process is performed in the order of a neck lower portion forming step for deforming the bent convex portion 141 and the bent concave portion 151 formed at the upper end of the neck portion, and a mouth portion forming step for forming the mouth portion 16 after the neck lower portion forming step. Hereinafter, details will be described in the order of these steps.

[Diameter reduction process]
By reducing the diameter of the opening end side of the tubular body 22 (necking), as shown in FIG. 3C, the curved convex portion 41 having a convex outer surface continuous with the cylindrical body 12 and the curved convex portion 41 are curved. An intermediate molded body having a curved concave portion 42 having a concave outer surface above the convex portion 41, a tapered tubular portion 14 continuous with the upper end of the curved concave portion 42, and a small diameter tubular portion 46 extending above the tapered tubular portion 14 in the can axial direction. (Second intermediate molded body described later) 24 is formed.

In this embodiment, the diameter reduction step includes the first diameter reduction step of forming the first convex curved portion 131 and the curved concave portion 42 from the upper end of the cylindrical body portion 12, and the tapered tubular portion continuous with the upper end of the curved concave portion 42. It comprises a second diameter reduction step of forming 14.
In the first diameter reduction step, as shown in FIG. 5, the necking die 51A is moved from the opening end side of the cylinder 22 in the can axis S direction, and the outer peripheral surface of the cylinder 22 is formed by the molding portion 52A of the necking die 51A. This is a process of reducing the diameter while pressing, and the upper end portion of the tubular body 22 is gradually reduced in diameter by using a plurality of necking dies 51A, 51B ... With different diameters of the molded portions 52A, 52B ... In descending order of diameter.

FIG. 5 shows a necking die 51A having the largest diameter of the molding portion 52A. When each necking die is represented by the necking die 51A, the necking die 51A is formed into a cylindrical shape as a whole. A molding portion 52A is formed on the tip end side of the peripheral portion. The molded portion 52A is formed by a convex curved surface continuous with the tip portion of the inner peripheral cylindrical surface 53A, and is formed so that the inner diameter gradually increases toward the tip end. At the cutting edge, a tubular guide portion 54 that fits on the outer peripheral surface of the tubular body 22 is formed.

FIG. 6 shows the final necking die 51D (molded in a dozen or so times) in the first diameter reduction step with a solid line, whereas some of the necking dies used before that are molded. It is the figure which showed the part 52A, 52B, 52C overlapped by the chain double-dashed line.
In this way, diameter reduction processing is performed while using a plurality of necking dies so that the inner diameters of the inner peripheral cylindrical surfaces of the molded portions 52A, 52B, and 52C are sequentially reduced.

By this first diameter reduction step, the upper part of the tubular body 22 is reduced in diameter, and the first intermediate molded body 23 shown in FIG. 7 is formed.
The first intermediate molded body 23 is formed in the shape of substantially the envelope surface of the molded portions 52A, 52B ... Of the necking dies 51A, 51B ..., And as shown in FIG. 7, is convex on the cylindrical body portion 12. It has a first convex curved portion 131 having an outer surface, a curved concave portion 42 having a concave outer surface continuous with the upper end of the first convex curved portion 131, and a tubular portion 45 continuous with the upper end of the curved concave portion 42. There is.
In the first intermediate molded body 23, the radius of curvature R1 of the outer surface of the first convex curved portion 131 is formed to be 20 mm or more and 30 mm or less, and the radius of curvature R4 of the outer surface of the curved recess 42 is formed to be 6 mm or more and 20 mm or less.

Next, in the second diameter reduction step, a tapered tubular portion 14 continuous with the upper end of the curved recess 42 is formed in the tubular portion 45 of the first intermediate 23. In this second diameter reduction step as well, as in the case of the first diameter reduction step, the tapered cylinder portion 14 is formed by using a plurality of necking dies and processing in ascending order of the diameter of the molded portion.

As shown in FIG. 4C, the second intermediate molded body 24 formed thereby has a first convex curved portion 131 connected to the upper end of the cylindrical body portion 12 and the first convex curved portion 131. A curved concave portion 42 connected to the upper end of the curved concave portion 42, a tapered tubular portion 14 continuous with the upper end of the curved concave portion 42, and a small diameter tubular portion 46 continuous with the upper end of the tapered tubular portion 14 via a bent convex portion 141 and a bent concave portion 151. Have.

[Reform process]
In this remodeling step, a necking die similar to the necking die in the diameter reduction step is used to remodel while pressing the curved recess 42.
As a result, as shown in FIG. 8, a concave curved portion 132 is formed at the lower end of the tapered tubular portion 14, and a second convex curved portion 133 is formed at the lower end of the concave curved portion 132. Further, the first convex curved portion 131 and the second convex curved portion 133 are connected by a tapered portion 34.

In the intermediate molded body 25, the radius of curvature R1 of the outer surface of the first convex curved portion 131 is 20 mm or more and 30 mm or less, and the radius of curvature R2 of the outer surface of the second convex curved portion 133 is 20 mm in the vertical cross section passing through the can shaft S. The inclination angle θ1 of the outer surface of the tapered portion 134 with respect to the can shaft S is 30 ° or more and 45 ° or less. The first convex curved portion 131 and the second convex curved portion 133 may be in a direct connection state. Further, the tapered portion 134 may be not only a linear tapered portion in a vertical cross section along the can axis but also a curved tapered portion close to a straight line.
The radius of curvature R3 of the outer surface of the concave curved portion 132 is 6.0 mm or more and 17.0 mm or less, and the inclination angle θ2 of the outer surface of the tapered tubular portion 14 with respect to the can shaft S is 5 ° or more and 10 ° or less.
Further, the small-diameter tubular portion 46 and the tapered tubular portion 14 are connected in a stepped manner by the bent convex portion 141 at the upper end of the tapered tubular portion 14 and the bent concave portion 151 at the lower end of the small-diameter tubular portion 46.

[Neck lower part forming process]
As shown in FIG. 9, the forming die 51M is pressed in the can axis S direction to be formed at a connecting portion between the upper end of the tapered tubular portion 14 of the third intermediate molded body 25 and the lower end of the small diameter tubular portion 46 above the tapered tubular portion 14. The bent convex portion 141 and the bent concave portion 151 are remolded. For example, the inner surface of the bent concave portion 151 is pressed by the molding portion 52M having a smaller radius of curvature to reduce the radius of curvature of the bent concave portion 151, or the vicinity of the connection portion between the bent convex portion 141 and the bent concave portion 151 is pressed. Then, the bending convex portion 141 is further bent to reduce its radius of curvature.
As a result, the radius of curvature of both or one of the bent convex portion 141 and the bent concave portion 151 becomes slightly smaller, but the change is slight, so that the intermediate molded body after the neck lower portion forming step is also the third intermediate molding. It will be described as a body 25.

[Mouth forming process]
Next, the small-diameter tubular portion 46 of the third intermediate molded body 25 is molded to expand the diameter of the small-diameter tubular portion 46, leaving the portion to be the neck portion 15, and the upper portion of the expanded portion is reduced in diameter again. Then, by performing screwing and curling, a bulging portion 161, a male screw portion 162, and a curling portion 163 form a continuous mouth portion 16 on the neck portion 15.
As a result, the bottle can 1 is formed.

The thickness of the aluminum alloy for forming the bottle can 1 is such that the original plate thickness before press molding is 0.370 mm or more and 0.550 mm or less, and the cylinder body after DI processing shown in FIG. 4 (b). In 22, the plate thickness (wall thickness) t1 of the bottom side portion 221 located on the bottom 11 side is formed to be 0.110 mm or more and 0.150 mm or less, and the plate thickness (flange thickness) t2 of the open end side portion 222 is 0. It is formed to be 200 mm or more and 0.240 mm or less. In this case, the bottom side portion 221 of the wall thickness t1 is slightly above the bottom portion 11 of the cylindrical body portion 12 in the can axis S direction, and is more than a portion that becomes a convex curved portion 131 of the diameter reduction portion 13 in a later step. Is slightly lower in the can axis S direction, and the opening end side portion 222 of the flange thickness t2 is an upper portion in the can axis S direction than the portion that becomes the convex curved portion 131 of the diameter reduction portion 13 in a later step. is there. The plate thickness of the dome portion 111 of the bottom portion 11 is substantially the original plate thickness or slightly thinner than the original plate thickness.

The bottle can 1 manufactured in this way is sealed with a cap (not shown) attached to the mouth portion 16.
This cap is a so-called pilfer proof cap having a top plate portion made of a thin metal of aluminum or an aluminum alloy and a peripheral wall portion, and slits are intermittently formed in the peripheral wall portion in the circumferential direction, and is a bottle can. After being put on the mouth portion 16 of 1, the peripheral wall portion is threaded along the male screw portion 162 of the bottle can 1, and the lower end portion of the peripheral wall portion is locked to the lower surface of the bulging portion 161.

The bottle can 1 has a reduced diameter portion 13 in which a first convex curved portion 131, a tapered portion 134, a second convex curved portion 133, and a concave curved portion 132 are formed between the cylindrical body portion 12 and the neck portion 15. Since the tapered tubular portion 14 is continuously formed, the length H2 from the cylindrical body portion 12 to the mouth portion 16 can be increased by the tapered tubular portion 14, and the capacity can be increased.
Further, since the cylindrical body portion 12 and the neck portion 15 have a shape in which the first convex curved portion 131, the concave curved portion 132, and the tapered tubular portion 14 are continuously formed, the neck portion is formed by the tapered tubular portion 14. The lower part of 15 is reinforced, and the radius of curvature R3 of the concave curved portion 132 at the lower end of the tapered cylindrical portion 14 is small, thereby increasing the column strength in the can axis S direction and preventing deformation during capping or the like. can do.
Further, the lower position of the bulging portion 161 is strengthened by changing the outer diameter stepwise by the bending concave portion 151 and the bending convex portion 141 from the neck portion 15 to the tapered tubular portion 14 below the bulging portion 161. Therefore, the deformation resistance can be increased.

The present invention is not limited to the configuration of each of the above embodiments, and various changes can be made to the detailed configuration without departing from the spirit of the present invention.
For example, as a bottle can, a bottomed cylindrical cylinder is formed in advance and the open end thereof is molded, but the cylinder includes a cylinder having no bottom, and after molding the reduced diameter portion, A separately formed bottom portion may be wound around the body portion of the cylinder.

After molding a DI can with a wall thickness of 0.135 mm and a flange thickness of 0.225 mm using a JIS3004 aluminum material with a plate thickness of 0.505 mm before press molding, the outer diameter D1 of the cylindrical body is 66. A bottle can having a diameter of 24 mm, an outer diameter of a bulging portion of the mouth of 38.0 mm, and an overall height of H0 of 203 mm was molded.
The radius of curvature R2 of the outer surface of the second convex curved portion and the radius of curvature R3 of the outer surface of the concave curved portion in the reduced diameter portion were measured. In these bottle cans, the inclination angle θ2 of the outer surface of the tapered cylinder portion with respect to the can axis was 5 ° to 10 °.
In addition, as a comparative example, a product formed without undergoing a reforming step was also produced.
Column strength was measured for these bottle cans.
For column strength, a flat plate is brought into contact with the upper end (opening) of the mouthpiece of the bottle, and a tester manufactured by Shimadzu Corporation (model number AG-50kNG) is used to compress in the axial direction at a speed of 5 mm / min to buckle. The load at the start of bending was measured.
The results are shown in Table 1. In each case, 10 cans are measured and the average value is shown.

As is clear from Table 1, the bottle cans of the examples have a high column strength of, for example, 1500 N or more. From this, it can be seen that if the radius of curvature R3 of the outer surface of the concave curved portion is 6.0 mm or more and 17.0 mm or less, deformation at the time of capping or the like can be suppressed. In addition, no pleats (vertical wrinkles) or molding marks were observed.
On the other hand, in Comparative Example 1, since it was formed without undergoing the reforming step, the radius of curvature of the concave curved portion (curved concave portion) was large and the column strength was low.

1 Bottle can 12 Cylindrical body 13 Reduced diameter 14 Tapered cylinder 15 Neck 16 Mouth 42 Curved recess 131 First convex curved part (convex curved part)
132 Concave curved part 133 Second convex curved part 134 Tapered part 141 Bending convex part 151 Bending concave part 161 Protruding part 162 Threaded part 163 Curled part

Claims (5)

It is connected to a cylindrical body having an outer diameter of 64.25 mm or more and 68.24 mm or less, a reduced diameter portion that is reduced in diameter from the upper end of the cylindrical body portion, and an upper end of the reduced diameter portion, and is directed upward in the can axis direction. The outer diameter of the tapered cylinder portion whose diameter is gradually reduced according to the diameter, the neck portion further reduced in diameter at the upper end of the tapered cylinder portion, and the bulging portion formed at the upper end of the neck portion and in which the cap material is entangled is 36. It is provided with a mouth portion of 0 mm or more and 40.0 mm or less, and the reduced diameter portion is a concave curved portion formed between a convex curved portion connected to the upper end of the cylindrical body portion and the lower end of the tapered tubular portion. It is a bottle can with a part and
The inclination angle of the outer surface of the tapered cylinder portion with respect to the can shaft is 5 ° or more and 10 ° or less.
A bottle can characterized in that the radius of curvature of the outer surface of the concave curved portion is 6.0 mm or more and 17.0 mm or less in a vertical cross section passing through a can shaft. A second convex curved portion having a convex outer surface is provided between the convex curved portion and the concave curved portion, and the radius of curvature of the outer surface of the second convex curved portion is 20 mm or more and 40 mm or less. The bottle can according to claim 1. It is connected to a cylindrical body having an outer diameter of 64.25 mm or more and 68.24 mm or less, a reduced diameter portion that is reduced in diameter from the upper end of the cylindrical body portion, and an upper end of the reduced diameter portion, and is directed upward in the can axis direction. The outer diameter of the tapered cylinder portion whose diameter is gradually reduced according to the diameter, the neck portion further reduced in diameter at the upper end of the tapered cylinder portion, and the bulging portion formed at the upper end of the neck portion and in which the cap material is entangled is 36. A concave curved portion having a mouth portion of 0 mm or more and 40.0 mm or less, and the reduced diameter portion formed between a convex curved portion continuous with the upper end of the cylindrical body portion and the lower end of the tapered tubular portion. It is a manufacturing method of a bottle can having
A cylinder forming step of forming a cylinder having the same outer diameter as the cylindrical body,
While pushing the necking die from the upper end of the cylinder in the can axis direction, the upper part of the cylinder is reduced in diameter to form the convex curved portion continuous with the upper end of the cylindrical body and above the convex curved portion. A diameter reduction step of forming a curved recess having a concave outer surface and the tapered cylinder portion continuous with the upper end of the curved recess.
A method for manufacturing a bottle can, which comprises a reforming step of forming the concave curved portion having a radius of curvature smaller than that of the curved concave portion by remolding the curved concave portion after the diameter reduction step. The bottle can according to claim 3, wherein in the reforming step, the concave curved portion is formed and a second convex curved portion is formed between the concave curved portion and the convex curved portion. Manufacturing method. A bending convex portion that protrudes outward in the radial direction is formed at the upper end of the tapered cylinder portion, and a bending concave portion that is continuous from the upper end of the bending convex portion is formed at the lower end of the neck portion. The method for manufacturing a bottle can according to claim 3 or 4, further comprising a neck lower portion forming step of deforming the bent convex portion and the bent concave portion to reduce the radius of curvature thereof.

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