JP2020147346A - Bottle can and its manufacturing method - Google Patents

Abstract

To provide a bottle can manufacturing method capable of shortening a manufacturing process and manufacturing a bottle can excellent in aesthetic property, and to provide a bottle can.SOLUTION: A bottle can includes a cylindrical tube body section, a diameter-reduced section whose diameter is reduced from the upper end part of the tube body section toward the upper side in the can axial direction, and a mouth section provided on the upper side in the can axial direction of the diameter-reduced section. A plurality of ribs extending in a direction inclined with respect to the circumferential direction of the diameter-reduced section are formed over the entire circumference of the diameter-reduced section, and the inclination angle of the rib with respect to the circumferential direction of the diameter-reduced section increases toward the upper side in the can axial direction.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. A bottle can is generally formed in a bottomed cylindrical shape having a body and a bottom, and a diameter-reduced portion that gradually reduces in diameter toward the opening side of the body is provided at the upper end of the diameter-reduced portion. It is configured to have a mouth. Such a bottle can has a bottomed cylindrical shape having a body and a bottom by subjecting a metal plate material (aluminum alloy material plate material) to a cutting process (squeezing process) and a DI process (squeezing and ironing process, Drawing & Ironing). The diameter-reduced portion is formed by subjecting the body of the bottomed cylindrical can to the diameter-reducing process. Further, in a bottle can, an uneven shape is designed on a reduced diameter portion.

For example, Patent Document 1 includes a bottle can (see FIG. 1 of Patent Document 1) in which a plurality of groove portions extending along an inclined direction are provided on the peripheral surface of a reduced diameter portion at intervals in the circumferential direction. A bottle can (see FIG. 9 of Patent Document 1) in which a plurality of grooves formed continuously along the circumferential direction of the diameter portion are provided at intervals in the can axial direction (axial direction), via a predetermined interval in the circumferential direction. A bottle can (see FIG. 12 of Patent Document 1) having a plurality of formed V-shaped grooves is disclosed. Further, Patent Document 2 also describes that these grooves are formed by pressing the reduced diameter portion inward in the radial direction and downward in the can axis direction by a mold.

Japanese Patent No. 5323757 Special Table 2017-526591

However, the bottle can having the above-mentioned shape is poor in design because the unevenness formed in the reduced diameter portion simply extends in the direction along the can axis direction. Further, in order to make the diameter-reduced portion a smooth shape, it is necessary to reduce the amount of processing at one time and perform the diameter-reducing processing many times. As the number of times of processing increases, it is necessary to arrange many molding dies side by side on the production line, and a large installation space is required. Therefore, the manufacturing cost increases.

The present invention has been made in view of such circumstances, and provides a method for manufacturing a bottle can and a bottle can which can shorten the manufacturing process and can manufacture a bottle can having excellent design. With the goal.

The bottle can of the present invention is provided with a cylindrical cylinder body portion, a reduced diameter portion whose diameter is reduced from the upper end portion of the cylinder body portion toward the upper side in the can axis direction, and an upper side of the reduced diameter portion in the can axis direction. A mouth portion is provided, and a plurality of ribs extending in a direction inclined with respect to the circumferential direction of the reduced diameter portion are formed in the reduced diameter portion over the entire circumference, and the ribs are formed with respect to the circumferential direction of the reduced diameter portion. The inclination angle increases toward the upper side in the can axis direction.

The circumferential direction of the reduced diameter portion means the circumferential direction of the reduced diameter portion when viewed from the front.
In the present invention, since a plurality of ribs extending in a direction inclined with respect to the circumferential direction of the reduced diameter portion are formed in the reduced diameter portion, the design of the bottle can can be improved. In particular, when the reduced diameter portion of the bottle can is exposed to light, the direction of light reflection differs depending on the portion of the spiral rib that is exposed to the light, so that the bottle can can be made to shine and its design can be improved. Further, since a plurality of ribs are formed in the reduced diameter portion, when the bottle can is gripped, the unevenness touches the fingers, so that there is a feeling of grip, and it becomes non-slip and easy to grip. In addition, since the ribs are inclined with respect to the circumferential direction of the reduced diameter portion, it seems that the internal liquid is agitated by the inner surfaces of the plurality of ribs when the internal liquid is poured into a glass or the like from a bottle can. And the foaming property can be improved.

Here, in the manufacturing process, the reduced diameter portion is formed by a die neck processing in which a plurality of reduced diameter dies are pressed in the can axis direction and relatively moved. At this time, if the number of times of diameter reduction using the diameter reduction die is small, step-like marks (horizontal streaks) remain in the circumferential direction of the bottle can, so that the diameter reduction portion can be formed into a smooth conical stand shape. Further, it is necessary to carry out a reforming step of pressing a plurality of diameter reduction dies to move them relative to each other, or to finely mold using many diameter reduction dies so as not to leave the stepped marks. On the other hand, in the present invention, a plurality of ribs are formed by pressing the rib forming die against the reduced diameter portion in the can axis direction and moving them relative to each other. Therefore, in the previous step, the stairs are formed in the circumferential direction of the bottle can. Even if the traces of the shape remain, the stepped traces can be made inconspicuous by the plurality of ribs. Therefore, the manufacturing process of the bottle can can be shortened as compared with the case where many molds for reducing the diameter are pressed to be finely molded or the reforming process is executed.

In a preferred embodiment of the bottle can of the present invention, the plurality of ribs have a cross section orthogonal to the can axis protruding in a triangular shape, and recesses are formed between the adjacent ribs to reduce the radius. Each of the radial outer tops of the plurality of ribs and the radial outer groove bottoms of the plurality of recesses in the cross section of the portion is formed in an arc shape, and the radius of curvature of the radial outer tops of the plurality of ribs. Is smaller than the radius of curvature of the groove bottom portion on the radial outer side of the plurality of recesses.

In the above aspect, since the radius of curvature of the tops of the plurality of ribs is small, clear ribs can be formed and the design is excellent.

In a preferred embodiment of the bottle can of the present invention, in the vertical cross section of the reduced diameter portion, the first tangent line between the top surfaces of the plurality of adjacent ribs and the second surface of the groove bottoms of the plurality of adjacent recesses are adjacent to each other. The distance from the tangent line is preferably 0.4 mm or more and 1.6 mm or less.
If the distance between the tangents is less than 0.4 mm, the height of the plurality of ribs (height of the unevenness) may become small, and the design of the bottle can may not be improved. If it exceeds .6 mm, the height of the plurality of ribs is too large, so that the rib forming becomes severe and defects may occur.

In a preferred embodiment of the bottle can of the present invention, an inclined surface is formed between the top portion and the bottom portion adjacent to the top portion in the vertical cross section of the reduced diameter portion, and is upward from the bottom portion in the can axis direction. The angle between the inclined surface inclined toward the top and the surface orthogonal to the can axis is 62 ° or more and 90 ° or less, and the inclination is inclined from the top toward the bottom on the upper side in the can axis direction. The angle between the surface and the surface orthogonal to the can axis is preferably 45 ° or more and less than 62 °.

If the angle between the inclined surface inclined from the bottom toward the upper top in the can axis direction and the surface orthogonal to the can axis is less than 62 °, the load capacity of the reduced diameter portion may decrease. On the other hand, if the angle between the inclined surface inclined from the bottom toward the top in the can axis direction and the surface orthogonal to the can axis exceeds 90 °, a plurality of recesses will enter the inside of the bottle can, resulting in a die neck. It is difficult to obtain the shape by processing. Further, if the angle between the inclined surface inclined from the top toward the bottom on the upper side in the can axis direction and the surface orthogonal to the can axis is less than 45 °, the load capacity of the reduced diameter portion may decrease. Since the inclination angle of the truncated cone-shaped truncated cone portion before forming the ribs is set to 62 °, it is difficult to process the angle beyond the above angle of 62 °.

As a preferred embodiment of the bottle can of the present invention, it is preferable that the plurality of ribs are arranged at equal intervals in the circumferential direction and an odd number of ribs are provided.
Here, when a plurality of ribs arranged at equal intervals in the circumferential direction are an even number, ribs having the same shape are arranged at opposite positions (180 ° opposite sides) in the radial direction of one rib. When a large number of bottle cans are transported together, the ribs of different bottle cans may collide with each other, and the bottle cans may be damaged or distorted, resulting in a decrease in transportability.
On the other hand, in the above aspect, since a plurality of ribs arranged at equal intervals in the circumferential direction are provided, a recess is formed at a corresponding position (180 ° opposite side) in the radial direction of one rib. Therefore, it is possible to prevent a plurality of ribs of different bottle cans from colliding with each other. Therefore, it is possible to suppress the bottle can from being damaged or distorted, it is possible to satisfactorily form a design having an uneven shape on the reduced diameter portion, and it is possible to ensure good transportability of the designed bottle can.

The method for manufacturing a bottle can of the present invention is the above-mentioned method for manufacturing a bottle can, which comprises a cylinder forming step of forming a cylindrical cylinder and a diameter reduction of the cylinder toward the upper side in the can axis direction. The reduced-diameter portion molding step for forming the reduced-diameter portion is provided, and the reduced-diameter portion molding step presses a plurality of diameter-reducing dies having different diameters on the molded surface against the cylinder and moves them relative to each other in the can axis direction. Thereby, a conical base portion forming step for forming the conical base portion and a small cylindrical portion linearly extending upward in the can axis direction along the can axis from the upper end portion of the conical base portion, and the conical base portion forming. The plurality of ribs are formed on the conical base portion by pressing a rib forming die for forming the plurality of ribs on the outer surface of the conical base portion formed by the process and moving them relative to each other to reduce the diameter. It includes a rib forming step as a part.

In the present invention, since a plurality of ribs can be formed by the same processing as forming the truncated cone portion, the manufacturing process can be shortened and a bottle can having excellent design can be manufactured.

In a preferred embodiment of the method for producing a bottle can of the present invention, the rib forming die has a convex surface forming a concave portion formed between the ribs adjacent to the truncated cone portion in a cross section orthogonal to the can axis. Are arranged side by side along the circumferential direction, and in the rib forming step, a plurality of the recesses are formed in the truncated cone portion by the plurality of the convex surfaces, and the truncated cone portion is woven into the groove portion between the convex surfaces. In this way, the plurality of ribs having a cross section orthogonal to the can axis protruding outward in the radial direction in a triangular shape may be formed.

In the above aspect, in the process of forming the plurality of recesses in the truncated cone by pressing the truncated cone with the convex surface forming the plurality of recesses, a part of the truncated cone (in the radial direction when forming the plurality of recesses). A plurality of ribs are formed so that the portion extruded to the outside) is woven into the groove portion. Therefore, a reduced diameter portion having a plurality of ribs can be easily formed.

According to the present invention, it is possible to shorten the manufacturing process and to manufacture a bottle can having excellent design.

It is a front view of the bottle can manufactured by the manufacturing method of the bottle can which concerns on one Embodiment of this invention. It is a top view of the bottle can shown in FIG. It is a cross-sectional view taken along the arrow A1-A1 shown in FIG. It is a cross-sectional view which shows the cross section which cut in the radial direction at the position of 40mm lower side in the can axis direction from the tip of the mouth of the bottle can shown in FIG. It is a figure which shows the cylinder formation process which manufactures a bottle can in the said embodiment. It is a front view which shows the intermediate molded body in the taper part molding process which manufactures a bottle can in the said embodiment. It is sectional drawing which shows the rib forming die for forming a plurality of ribs in a taper part in the said embodiment. FIG. 7 is a cross-sectional view taken along the line B1-B1 of the rib forming die shown in FIG. It is a front view which shows the intermediate molded body after the rib molding process in the said embodiment.

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

FIG. 1 is a front view of a bottle can 1 manufactured by the method for manufacturing a bottle can according to an embodiment of the present invention, FIG. 2 is a top view of the bottle can 1, and FIG. 3 is a top view of the bottle can 1. It is a cross-sectional view taken along the line A1-A1 shown in FIG. 1, and FIG. 4 shows a radius of 40 mm below the can axis O direction (the middle portion of the reduced diameter portion 12) from the mouth portion 16 of the bottle can 1. It is a cross-sectional view which shows the cross section cut in the direction. The bottle can 1 is used as a container for accommodating beverages and the like by attaching a cap (not shown) to the opening end. Further, FIGS. 5 to 9 are explanatory views showing each step of the method for manufacturing a bottle can of the present embodiment. Of these, FIG. 5 is a schematic view showing the steps from forming the cup to forming the tubular body 41 in order, and FIGS. 6 to 9 are views for explaining the diameter-reduced portion forming step.

The bottle can 1 is made of a thin metal such as aluminum or an aluminum alloy, and has a bottomed cylindrical shape having a cylindrical body (wall) 10 and a dome-shaped bottom (bottom) 20 as shown in FIG. Is formed in. As shown in FIG. 1, the body portion 10 and the bottom portion 20 are arranged coaxially with each other, and in the present embodiment, these common axes will be referred to as can axes O and will be described.

Further, among the directions along the can shaft O (can shaft O direction), the direction from the opening end 10a of the body portion 10 toward the bottom 20 side is downward, and the direction from the bottom 20 toward the opening end 10a is upward. In the following description, the vertical direction shall be determined in the same manner as the directions shown in FIGS. 1 to 9. Further, the direction orthogonal to the can axis O is called the radial direction, and among the radial directions, the direction approaching the can axis O is the inside (inside) of the radial direction, and the direction away from the can axis O is the outside of the radial direction (the direction away from the can axis O). Outer). Further, the direction of orbiting around the can shaft O is defined as the circumferential direction.

As shown in FIG. 1, the body portion 10 has a cylindrical body portion 11 formed in a cylindrical shape on the bottom portion 20 side, and from the upper end portion of the cylinder body portion 11 to the upper side in the can shaft O direction (open end portion 10a side). A diameter-reduced portion 12 whose diameter is reduced toward the end and a mouth portion 16 provided on the upper side of the diameter-reduced portion 12 in the can axis O direction are provided.

As shown in FIG. 3, the inclination angle θ0 of the reduced diameter portion 12 with respect to the plane orthogonal to the can axis O is set to 40 ° or more and 80 ° or less, and is set to 62 ° in the present embodiment. The cylinder body portion 11 and the diameter-reduced portion 12 each form an annular shape extending over the entire circumference of the body portion 10 in the circumferential direction.
Further, the cylinder body portion 11 and the diameter-reduced portion 12 are smoothly connected to each other, and are smoothly connected to each other without forming a step. Specifically, a connecting portion 15 formed of a convex curved surface that is convex outward and upward in the radial direction is provided between the cylinder body portion 11 and the diameter reducing portion 12, and the connecting portion 15 provides a cylinder. The body portion 11 and the lower end portion of the reduced diameter portion 12 are connected.

Further, the mouth portion 16 arranged at the upper part of the body portion 10 is formed at the large diameter portion 161 once expanded at the position on the upper side of the reduced diameter portion 12 in the can axis O direction and the upper end of the large diameter portion 161. It has a threaded portion 162 and a curled portion 163 formed at an open end portion 10a at the upper end of the threaded portion 162. As described above, the mouth portion 16 is opened to the outside by the opening end portion 10a, and the contents such as beverages are filled inside the bottle can 1 through the mouth portion 16. By attaching a cap (not shown) to the mouth portion 16, the contents filled inside the bottle can 1 are sealed.

Of these, the reduced diameter portion 12 has a plurality of ribs 13 that are inclined with respect to the circumferential direction of the reduced diameter portion 12 when viewed from the front and extend from the lower side in the can shaft O direction to the upper side in the can shaft O direction. It has. Each of these ribs 13 is set so that the inclination angle of the reduced diameter portion 12 with respect to the circumferential direction increases toward the upper side in the can axis O direction. For example, as shown in FIG. 1, the inclination angle θ10 of each rib 13 at the lower end of the reduced diameter portion 12 with respect to the circumferential direction of the reduced diameter portion 12 is set to 40 °, and the inclination angle θ10 is set toward the upper side in the can axis O direction. The inclination angle θ10 is large. That is, the plurality of ribs 13 have a so-called spiral shape. Each such rib 13 is formed so as to project outward in the radial direction, and a recess 14 is formed between the adjacent ribs 13. For example, it is preferable that a plurality of ribs 13 are formed in an odd number in a range of 5 or more and 25 or less, preferably 11 or more and 19 or less over the entire circumference of the reduced diameter portion 12. For example, in the example shown in FIG. 1, 15 ribs 13 are formed. If the number of ribs 13 is small, wrinkles are likely to occur during molding, and if the number is too large, it becomes difficult to process.

The cross section of the reduced diameter portion 12 on which the rib 13 is formed orthogonal to the can axis O has the shape shown in FIG. Specifically, each of the plurality of ribs 13 has a cross section perpendicular to the can shaft O protruding in a triangular shape (mountain shape). Further, each of the radial outer top 131 of the plurality of ribs 13 and the radial outer groove bottom 141 (the top of the recess 14) of the plurality of recesses 14 in the reduced diameter portion 12 is formed in an arc shape. There is. The radius of curvature R1 of the top 131 on the radial outer side of the plurality of ribs 13 is set to be smaller than the radius of curvature R2 of the groove bottom 141 on the radial side of the plurality of recesses 14. Further, since the inclination angle of the rib 13 with respect to the circumferential direction of the reduced diameter portion 12 increases toward the upper side in the can axis O direction, as shown in FIG. 4, it is arranged between the groove bottom portions 141 of the adjacent recesses 14 and between them. The angles θ3 and θ4 of the rib 13 with respect to the top 131 are different from each other. For example, the angle θ3 between the groove bottom 141 of the recess 14 located on the left side in FIG. 4 and the top 131 of the rib 13 is 12.5 °, and the groove bottom 141 and the rib 13 of the recess 14 located on the right side in FIG. 4 have an angle θ3. The angle θ4 with the top 131 is 11.5 °.

Further, the radial width w4 between the circumscribed circle that abuts each of the top 131 of the plurality of ribs 13 and the groove bottom 141 of the plurality of recesses 14 is preferably 0.4 mm or more and 1.2 mm or less. In the embodiment, it is set to 0.62 mm. That is, the depth dimension of each recess 14 is set to 0.62 mm. Further, the width dimension of the rib 13 in the circumferential direction is formed so that the mutual spacing gradually decreases from the lower side to the upper side in the can axis O direction. For example, in the plurality of ribs 13, the width w1 on the lower side in the can shaft O direction is 7.4 mm to 37.0 mm, and the width w2 on the upper side in the can shaft O direction is 5 mm to 26.0 mm.

Further, in the vertical cross section of the reduced diameter portion 12 shown in FIG. 3, the first tangent line S1 between the top 131 surfaces of the plurality of adjacent ribs 13 and the second tangent line S2 between the groove bottom portions 141 of the plurality of adjacent recesses 14 The interval w3 is set to 0.4 mm or more and 1.6 mm or less. The distance w3 is the same as the radial width w4 between the circumscribed circles of the top 131 surfaces of the plurality of adjacent ribs 13 and the circumscribed circles of the groove bottoms 141 surfaces of the plurality of adjacent recesses 14. That is, the interval w3 indicates the depth dimension of each recess 14, and is set to, for example, 0.62 mm.
If the interval w3 is less than 0.4 mm, the heights (heights of irregularities) of the plurality of ribs 13 may become small, and the design of the bottle can 1 may not be improved, and the interval w3 is 1.6 mm. If the height exceeds the above, the heights of the plurality of ribs 13 are too large, so that the rib forming becomes severe and defects may occur.

Further, the arc-shaped top 131 of the rib 13 and the arc-shaped groove bottom 141 of the adjacent recess 14 are linear in the vertical cross section of the reduced diameter portion 12 shown in FIG. 3 along the can axis O direction. An inclined surface is formed. Of these, the angle θ2 between the first inclined surface 130 inclined from the groove bottom 141 toward the upper top 131 in the can axis O direction and the surface orthogonal to the can axis O is set to 62 ° or more and 90 ° or less. The angle θ1 between the second inclined surface 140 inclined from the top 131 toward the groove bottom 141 on the upper side in the can axis O direction and the surface orthogonal to the can axis O is set to 45 ° or more and less than 62 °. For example, in the present embodiment, the angle θ1 is set to 56.1 ° and the angle θ2 is set to 67.6 °.

If the angle θ2 between the first inclined surface 130 inclined from the groove bottom 141 toward the top 131 of the rib 13 on the upper side in the can axis O direction and the surface orthogonal to the can axis O is less than 62 °, the diameter-reduced portion The load capacity of 12 may decrease. On the other hand, when the angle θ2 between the first inclined surface 130 inclined from the groove bottom 141 toward the top 131 of the rib 13 on the upper side in the can axis O direction and the surface orthogonal to the can axis O exceeds 90 °, the plurality of recesses 14 Is a shape that fits inside the bottle can 1, so it is difficult to obtain this shape by die neck processing. Further, if the angle θ1 between the second inclined surface 140 inclined from the top 131 toward the groove bottom 141 of the recess 14 on the upper side in the can axis O direction and the surface orthogonal to the can axis O is less than 45 °, the diameter-reduced portion Since the load capacity of the 12 may decrease and the inclination angle of the truncated cone portion 12a (see FIG. 6) before forming the plurality of ribs 13 is set to 62 °, the above angle is 62 °. It is difficult to process with an angle exceeding.

Further, FIG. 3 shows distances L1 to L3 along the can axis O direction between the top 131 (highest position) of the rib 13 and the deepest portion 141 of the groove bottom 141 of the recess 14. Specifically, the distance L2 between the deepest portion of the groove bottom 141 of the first recess 14 and the top 131 of the first rib 13 along the can shaft O direction from the lower side in the can shaft O direction is the first recess 14. The distance L1 between the starting point of the second inclined surface 140 and the deepest part of the groove bottom 141 of the first recess 14 and the top 131 and the second recess 14 of the first rib 13 are inclined toward the groove bottom 141 of the first rib 13. The distance from the deepest portion of the groove bottom portion 141 of the above is set to be larger than the distance L3. Further, the distance L1 and the distance L3 are the same.
For example, the distances L1 and L3 are set to 5 mm, and the distance L2 is set to 6 mm.

Further, as will be described in detail later, when the plurality of ribs 13 are formed by pressing and moving the rib forming die, the ribs 13 are woven outward in the radial direction when forming each of the recesses 14. The top 131 of each rib 13 is formed. Therefore, the top 131 of the plurality of ribs 13 protrudes radially outward from the tapered surface connecting the upper end and the lower end of the reduced diameter portion 12. Since such a plurality of ribs 13 are formed, when the bottle can 1 is gripped, the unevenness touches the fingers, so that there is a feeling of grip, it becomes non-slip and it becomes easy to grip, and the bottle can 1 The design can be improved.

The height (height of the bottle can 1) e from the bottom surface of the bottom portion 20 of the bottle can 1 thus formed to the top surface of the curl portion 163 is set to 130 mm to 205 mm. Further, the height a from the upper surface of the curl portion 163 to the upper end portion of the reduced diameter portion 12 in the can axis O direction is preferably set to 24 mm to 32 mm, more preferably 26 mm to 30 mm. Further, the length b of the reduced diameter portion 12 from the upper end portion in the can shaft O direction to the lower end portion is set to 23 mm to 30 mm, more preferably 25 mm to 28 mm. In the present embodiment, the height b of the reduced diameter portion 12 provided with the plurality of ribs 13 is set within the above range, so that the grip feeling of the bottle can 1 is further enhanced.
To give an example of other dimensions, the height c of the reduced diameter portion 12 from the lower end portion in the can axis O direction to the bottom portion 20 is set to 65 mm to 140 mm, more preferably 70 mm to 138 mm, and the bottom portion 20. The height d is set to 5 mm to 9 mm. Further, the outer shape f of the cylinder body portion 11 is set to 50 mm to 70 mm, more preferably 53 mm to 67 mm. However, the above dimensions are not limited to the above numerical range.

The bottle can 1 having the reduced diameter portion 12 on which the plurality of ribs 13 are formed is manufactured by the manufacturing method described below. The method for manufacturing the bottle can 1 includes a cylinder forming step, a reduced diameter portion forming step, and a mouth portion forming step.

[Cylindrical body forming process]
First, an aluminum plate material such as an aluminum alloy is punched out and drawn to form a shallow cup 40 having a relatively large diameter as shown in FIG. 5A, and then the cup 40 is drawn and ironed again. (DI processing) is added to form a bottomed cylindrical cylindrical body 41 having a predetermined height as shown in FIG. 5 (b), and the upper end thereof is trimmed and aligned. By this DI processing, the bottom portion of the tubular body 41 is formed into the shape of the bottom portion 20 as the final bottle can 1. The original plate thickness before press forming is 0.250 mm to 0.500 mm, and the plate thickness (wall thickness) t1 on the bottom 20 side of the tubular body 41 shown in FIG. 5 (b) is 0.100 mm. It is formed to be ~ 0.250 mm, and the plate thickness (flange thickness) t2 on the opening end side is formed to be 0.200 mm to 0.400 mm.

[Reduced diameter molding process]
The diameter-reduced portion forming step includes a truncated cone forming step of forming the truncated cone portion 12a and a rib forming step of forming a plurality of ribs 13 on the truncated cone portion 12a to form the truncated cone portion 12.

(Frustrated cone forming process)
In the truncated cone forming step, the tubular body 41 formed up to the state shown in FIG. 5 (b) has a plurality of reduced diameters having annular molded surfaces having different processing diameters shown by the two-point chain line in FIG. 5 (b). By pressing the truncated cones 70 (dinecking molds) in descending order of machining diameter and moving them relative to the can shaft O, the angle with respect to the can shaft O is 40 ° or more and 80 ° or less (62 ° in this embodiment). For a truncated cone portion 12a having a linear longitudinal cross section passing through the can shaft O, and for a mouth portion extending linearly upward in the can shaft O direction from the upper end portion of the truncated cone portion 12a along the can shaft O. The cylindrical portion 16a is formed. The shape shown in FIG. 6 is the intermediate molded body 42 in which the truncated cone portion 12a and the cylindrical portion 16a for the mouth portion are formed.

(Rib formation process)
A plurality of ribs 13 are formed on the outer surface of the truncated cone portion 12a of the intermediate molded body 42 in the state shown in FIG. 6 by using the rib forming dies 60 shown in FIGS. 7 and 8. The rib forming die 60 is formed in a cylindrical shape as a whole, and the tip portion of the inner peripheral portion thereof is formed in a tapered shape that gradually expands in diameter toward the tip direction, so that the tip portion in the axial direction is formed. A tapered molded portion 61 is formed in the portion, and a cylindrical guide portion 62 is formed in the base end portion. Then, on the tapered molded portion 61, a ridge (convex surface 612) extending so that the angle of the tapered molded portion 61 with respect to the circumferential direction when viewed from the front increases toward the upper side in the can axis O direction is formed in the circumferential direction. A plurality of portions are formed at equal intervals with mutual intervals, and groove portions 611 are formed between the convex surfaces 612. That is, in the rib forming die 60, in the cross section along the B1-B1 line of FIG. 7, a plurality of spiral convex surfaces 612 forming the plurality of recesses 14 are arranged side by side along the circumferential direction.

Then, in a state where the shaft C2 of the rib molding die 60 and the can shaft O of the intermediate molding 42 are aligned with each other, the tapered molding portion 61 of the rib molding die 60 is placed at the open end of the intermediate molding 42. By arranging them facing each other and bringing them closer to the can shaft O direction, the cone base portion 12a is pressed in the can shaft O direction so as to form from the lower end portion to the upper end portion. As a result, the truncated cone portion 12a is pressed by the convex surface 612 forming the plurality of recesses 14, whereby the plurality of recesses 14 are formed on the truncated cone portion 12a, and in the process, a part (plurality) of the truncated cone portion 12a is formed. A plurality of ribs 13 are formed so that a portion (a portion that is extruded radially outward when forming the concave portion 14) is woven into the groove portion 611. As a result, a plurality of ribs 13 are formed over the entire circumference of the truncated cone portion 12a to form a reduced diameter portion 12.

[Mouth forming process]
Then, as shown in FIG. 1, a large diameter portion 161 having a diameter larger than the upper end of the reduced diameter portion 12 is formed on the cylindrical portion 16a for the mouth of the intermediate molded body 42 in the state shown in FIG. After forming the large diameter portion 161, the threaded portion 162 of the cap is screwed with the threaded portion (not shown). Finally, the upper end portion of the mouth portion cylindrical portion 16a is curled to form the curl portion 163, and the bottle can 1 having the mouth portion 16 is manufactured.

The inside of the bottle can 1 manufactured in this manner is filled with contents such as beverages, a cap (not shown) is wrapped around the mouth portion 16, and a container whose inside is sealed is manufactured. ..

Since the bottle can 1 according to the present embodiment described above has a plurality of ribs 13 extending in a direction inclined with respect to the circumferential direction of the reduced diameter portion 12, the design of the bottle can 1 can be improved. In particular, when the reduced diameter portion of the bottle can 1 is exposed to light, the light reflection direction differs depending on the portion of the spiral rib 13 exposed to the light, so that the bottle can 1 can be made to shine and its design can be improved. Can be improved. Further, since the plurality of ribs 13 are formed in the reduced diameter portion 12, when the bottle can 1 is gripped, the unevenness touches the fingers, so that there is a feeling of grip, and it becomes non-slip and easy to grip. In addition, since the rib 13 is inclined with respect to the circumferential direction of the reduced diameter portion 12, a plurality of ribs 13 are formed on the reduced diameter portion 12, so that the internal liquid can be poured into the glass or the like from the bottle can 1. At the time of pouring, the internal liquid is made to be agitated by the inner surfaces of the plurality of ribs 13, and the foaming property can be improved.

Further, since a plurality of ribs 13 arranged at equal intervals in the circumferential direction are provided, the recesses 14 are formed at the corresponding positions (180 ° opposite sides) in the radial direction of one rib 13. Therefore, it is possible to prevent the plurality of ribs 13 of different bottle cans 1 from colliding with each other. Therefore, it is possible to prevent the bottle can 1 from being damaged or distorted, it is possible to satisfactorily form a design having an uneven shape on the reduced diameter portion 12, and it is possible to satisfactorily secure the transportability of the designed bottle can 1.

Further, since the plurality of ribs 13 are formed by pressing the rib forming die 60 and moving them relative to each other, a stepped trace generated when the truncated cone portion 12a is formed in the circumferential direction of the bottle can 1 remains. Even so, the plurality of ribs 13 can make the stepped traces inconspicuous. Therefore, the manufacturing process of the bottle can 1 can be shortened as compared with the case where many molds for reducing the diameter are pressed to form finely or the reforming process is executed.

Further, since the plurality of ribs 13 can be formed by the same processing method as the die necking process for forming the reduced diameter portion in the conventional bottle can, the manufacturing process can be shortened and the bottle can 1 having excellent design can be manufactured. ..

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 41 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.

In the above embodiment, the inclination angle θ10 of each rib 13 at the lower end of the reduced diameter portion 12 with respect to the circumferential direction is set to 40 °, but the inclination angle is not limited to this. Can be set freely. For example, it may be set to 140 °. In this case, the angle of each rib 13 with respect to the circumferential direction of the reduced diameter portion 12 is opposite. That is, the spiral direction may be opposite.

1 Bottle can 10 Body 10a Opening end 11 Cylinder body 12 Reduced diameter 13 Rib 130 First inclined surface (inclined part)
131 Top 14 Recess 140 Second inclined surface (inclined surface)
141 Groove bottom 15 Connection 16 Mouth 16a Mouth cylinder (small cylinder)
20 Bottom 40 Cup 41 Cylinder 42 Intermediate molded body (cylinder)
60 Rib forming die 61 Tapered forming part 611 Groove part 612 Convex surface 62 Cylindrical guide part 161 Large diameter part 162 Threaded part 163 Curled part S1 First tangent S2 Second tangent

Claims (7)

It is provided with a cylindrical cylinder body portion, a reduced diameter portion whose diameter is reduced from the upper end portion of the cylinder body portion toward the upper side in the can axis direction, and a mouth portion provided on the upper side of the reduced diameter portion in the can axis direction.
A plurality of ribs extending in a direction inclined with respect to the circumferential direction of the reduced diameter portion are formed in the reduced diameter portion over the entire circumference, and the inclination angle of the reduced diameter portion with respect to the circumferential direction is upward in the can axis direction. A bottle can that grows larger toward the end. The plurality of ribs have a cross section orthogonal to the can axis protruding in a triangular shape, and recesses are formed between the adjacent ribs.
Each of the radial outer tops of the plurality of ribs and the radial outer groove bottoms of the plurality of recesses in the cross section of the reduced diameter portion is formed in an arc shape, and the radial outer tops of the plurality of ribs are formed. The bottle can according to claim 1, wherein the radius of curvature of the plurality of recesses is smaller than the radius of curvature of the groove bottom portion on the outer side in the radial direction of the plurality of recesses. In the vertical cross section of the reduced diameter portion, the distance between the first tangent line between the top surfaces of the plurality of adjacent ribs and the second tangent line between the groove bottom surfaces of the plurality of adjacent recesses is 0.4 mm or more. The bottle can according to claim 2, wherein the bottle can has a diameter of 6 mm or less. In the vertical cross section of the reduced diameter portion, an inclined surface is formed between the top portion and the groove bottom portion adjacent to the top portion.
The angle between the inclined surface inclined from the bottom of the groove toward the top on the upper side in the can axis direction and the surface orthogonal to the can axis is 62 ° or more and 90 ° or less, and the top is on the upper side in the can axis direction. The bottle can according to claim 2 or 3, wherein the angle between the inclined surface inclined toward the groove bottom and the surface orthogonal to the can axis is 45 ° or more and less than 62 °. The bottle can according to any one of claims 1 to 4, wherein the plurality of ribs are arranged at equal intervals in the circumferential direction and an odd number of ribs are provided. The method for manufacturing a bottle can according to claim 1.
A tubular body forming step of forming a cylindrical tubular body and a reduced diameter portion forming step of forming a reduced diameter portion by reducing the diameter of the tubular body toward the upper side in the can axis direction are provided.
In the reduced diameter portion molding step, a plurality of reduced diameter dies having different diameters on the molding surface are pressed against the cylinder and moved relative to each other in the can axis direction, thereby causing the truncated cone portion and the upper end portion of the truncated cone portion. A truncated cone forming step for forming a truncated cone portion linearly extending upward in the can axis direction along the can axis, and a plurality of the above-mentioned plurality of truncated cone portions formed on the outer surface of the truncated cone portion formed by the truncated cone forming step. It is characterized by comprising a rib forming step of forming the plurality of ribs on the truncated cone portion to form a reduced diameter portion by pressing a rib forming die for forming the ribs and moving them relative to each other. How to make a bottle can. In the rib forming die, a plurality of convex surfaces forming recesses formed between the ribs adjacent to the truncated cone portion are arranged side by side in the circumferential direction in a cross section orthogonal to the can axis.
In the rib forming step, a plurality of the recesses are formed in the truncated cone portion by the plurality of the convex surfaces, and the truncated cone portion is woven into the groove portion between the convex surfaces so that the cross section orthogonal to the can axis is formed. The method for manufacturing a bottle can according to claim 6, wherein the plurality of ribs projecting outward in the radial direction in a triangular shape are formed.

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