JP6877943B2 - How to make bottle cans - Google Patents

Description

The present invention relates to a method for producing a bottle can.

As a method for manufacturing such a bottle can, for example, Patent Document 1 describes that it is manufactured from a metal material such as an aluminum alloy by drawing, squeezing, or impact forming, and the can body has a threaded portion as a cap mounting portion. In a threaded metal can that consists of a mouth, tapered shoulder, body and bottom, and can maintain high sealing performance by screwing a cap, a tapered shape that expands in the radial direction from the lower end of the threaded part of the mouth. It is described that a concave portion that curves smoothly inward is formed around the upper end of the shoulder portion of the shoulder portion, and a convex portion that continuously curves outward smoothly below the concave portion is formed. Further, in Patent Document 1, the degree of curvature of the smooth convex portion continuous from the concave portion is set to an inclination angle of 35 ° to 60 ° with respect to the vertical direction, that is, a can axis, specifically, an inclination angle of 45 °. Is stated to be preferable.

Further, for example, in Patent Document 2, a screw portion is provided on the upper outer periphery of a base portion formed by reducing the diameter of an opening of a metal can body (bottomed cylindrical body) such as an aluminum alloy formed in a bottomed tubular shape. This is a method for manufacturing a bottle can in which a bulging portion for winding the lower part of the cap body is formed below the screw portion as well as being provided. The diameter is expanded again by a predetermined distance from the opening end of the base portion to form a diameter-expanded portion, and after the diameter-expanded portion is formed, the diameter of the portion forming the screw is reduced and the diameter of the screw portion is reduced. A method for manufacturing a bottle can, which is formed by threading a diametered portion and is formed by an enlarged diameter portion remaining without being reduced in diameter when forming the threaded portion, is described. .. In this case, a neck portion extending from the shoulder portion to the upper end side is formed below the bulging portion in the mouthpiece portion having a reduced diameter of the opening portion.

Here, in the molding of the shoulder portion as described above, a plurality of cylindrical dies whose inner diameters gradually decrease are press-fitted into the upper end side portion of the cylindrical portion of the bottomed cylinder in order from the one having the largest inner diameter. By plastically deforming, the lower end side portion of the upper end side portion of the cylindrical portion is inclined toward the upper end side in a stepwise manner toward the inner peripheral side, and the inner peripheral side of the inclined lower end side portion. This is done by gradually reducing the diameter of the cylinder into a cylindrical shape with a smaller inner diameter.

Further, the molding of the bulging portion described in Patent Document 2 is slightly larger than the inner diameter of the bulging portion after the cylindrical neck portion having a reduced diameter is formed on the inner peripheral side of the shoulder portion inclined in this way. A diameter-expanding tool having an outer peripheral portion at the lower end of the outer diameter is inserted into the neck from the upper end side to expand the diameter, and then thread cutting is performed on the upper end side of the expanded portion, so that the diameter is reduced by thread cutting as described above. It is molded as the part left behind.

Japanese Unexamined Patent Publication No. 2001-21316 Japanese Patent No. 4908544

By the way, in recent years, there has been a strong demand for further thinning of the can body in order to save resources and energy during material production of the metal material forming such a bottle can. For example, a bottle can made of an aluminum alloy. In the case of, the cup-shaped material formed by drawing from a metal plate made of an aluminum alloy having a plate thickness of about 0.230 mm to 0.300 mm is re-squeezed and ironed to form a bottomed cylindrical body as described above. It is also required to form a can body of a bottle can by forming a shoulder portion, a neck portion, and a bulging portion and threading the can body.

However, in a bottle can in which the bottomed cylinder is thinned in this way, the strength of the bottomed cylinder is reduced, and as described in Patent Document 1, the inclination angle of the convex portion with respect to the can shaft is increased. If the load is large and the load for molding the neck is large, or if the load for molding the bulge described in Patent Document 2 is large, the bottom is formed when the neck and bulge are molded. Buckling may occur in the cylinder. In particular, when molding a bottomed cylinder, the lower end side portion of the bottomed cylinder portion is more than the upper end side portion of the bottomed cylinder portion forming the shoulder portion, the neck portion, the bulging portion and the cap mounting portion. The wall thickness may be reduced, and in such a bottomed cylinder, buckling at the lower end side portion of the thinned body portion becomes more remarkable.

The present invention has been made under such a background, and even if the metal plate or the bottomed cylinder to be molded on the can body of the bottle can is thinned, the neck portion or the bulging portion is formed. It is an object of the present invention to provide a method for manufacturing a bottle can that can prevent buckling of a bottomed cylinder.

In order to solve the above problems and achieve such an object, the present invention firstly applies to an outer peripheral portion formed integrally with the bottom portion of the can body, and from the bottom portion to the upper end opening of the can body. A cylindrical body centered on the can shaft, a shoulder portion whose diameter decreases toward the upper end side, a neck portion extending further toward the upper end side from this shoulder portion, and a cap attachment portion are formed in this order. A method for manufacturing a bottle can, in which a cup-shaped material formed by drawing from a metal plate having a plate thickness of 0.230 mm to 0.300 mm is re-squeezed, squeezed, and bottom-shaped, and the bottom and the bottom are formed. With the same outer diameter as the body , the thickness of the shoulder, neck, and upper end of the cap attachment is 0.180 mm to 0.225 mm, and the thickness of the lower end of the body is 0.180 mm to 0.225 mm. The shoulder portion and the shoulder portion are formed by a DI press step of forming a bottomed cylindrical body in which a cylindrical portion thinner than the upper end side portion is formed, and by reducing the diameter of the upper end side portion of the bottomed cylindrical body. In the bottleneck molding step, a bottleneck molding step of molding the neck portion whose diameter is further reduced toward the upper end side and a cap mounting portion molding step of molding the cap mounting portion on the upper end portion of the neck portion are provided. Molds the inclination angle of the neck-reduced portion with respect to the can shaft in the range of 18 ° to 24 °, and extends from the upper end of the shoulder to the minimum diameter-reduced position of the neck-reduced portion. It is characterized in that the amount of reduction of the outer diameter in the radial direction with respect to the can shaft is in the range of 0.5 mm to 2.2 mm.

Secondly, the present invention has a cylindrical body portion centered on the can shaft in order from the bottom portion toward the upper end opening of the can body on the outer peripheral portion integrally molded with the bottom portion of the can body. A method for manufacturing a bottle can, in which a shoulder portion whose diameter decreases toward the upper end side, a neck portion extending further toward the upper end side from the shoulder portion, and a cap attachment portion are formed, and the plate thickness is 0.230 mm or more. A cup-shaped material formed by drawing from a 0.300 mm metal plate is re-squeezed, squeezed, and bottom-formed to have the same outer diameter as the bottom and the body, and the shoulder, neck, and so on. And a bottomed portion having a cylindrical portion having a thickness of the upper end side portion serving as the cap mounting portion of 0.180 mm to 0.225 mm and a thickness of the lower end side portion serving as the body portion thinner than that of the upper end side portion. A DI press process for forming a cylindrical body, a bottleneck forming step for forming the shoulder portion and the neck portion by reducing the diameter of the upper end side portion of the bottomed cylindrical body, and an outer peripheral side at the upper end portion of the neck portion. It is provided with a cap mounting portion molding step of molding the cap mounting portion through a bulging portion that swells to the top, and in the cap mounting portion molding step, the bulging portion is expanded in diameter from the upper end of the neck portion in the bulging portion. The inclination angle of the diameter portion with respect to the can shaft is formed in the range of 18 ° to 24 °, and the diameter expansion amount of the inner diameter in the diameter direction with respect to the can shaft from the upper end of the neck portion to the maximum bulge position of the bulge portion. Is in the range of 0.5 mm to 2.2 mm.

In the method for manufacturing a bottle can as described above, the inclination angle of the diameter-reduced portion of the neck at the neck and the enlarged diameter of the bulge at the bulge with respect to the can shaft is in the range of 18 ° to 24 ° with respect to the can shaft. Therefore, it is possible to reduce the load in the can axis direction when molding by reducing the diameter of the neck part by inserting a mold or a diameter expansion tool or when molding by expanding the diameter of the bulging part. it can. In addition, the amount of diameter reduction in the radial direction with respect to the can shaft from the upper end of the shoulder to the minimum diameter reduction position of the neck contraction portion and the inner diameter in the radial direction with respect to the can shaft from the upper end of the neck portion to the maximum bulge position of the bulge portion. The amount of diameter expansion is as small as 0.5 mm to 2.2 mm, that is, the amount of molding of the neck and bulge itself is small, so the load acting on the bottomed cylinder when molding these neck and bulge. Can be suppressed.

Therefore, according to the method for manufacturing a bottle can having the above configuration, the thickness of the metal plate formed into the cup-shaped material is as thin as 0.230 mm to 0.300 mm, and the bottom is formed from the cup-shaped material. Even if the thickness of the upper end side portion of the cylindrical portion of the cylindrical body is as thin as 0.180 mm to 0.225 mm, and the thickness of the lower end side portion of the cylindrical portion is thinner than this, these neck portions and bulging portions It is possible to prevent the bottomed cylinder from buckling due to the load during molding. Therefore, it is possible to reduce the thickness of the can body of the bottle can without causing a decrease in the manufacturing yield and manufacturing efficiency of the bottle can due to such buckling, and it is possible to promote further resource saving and energy saving. It becomes.

Here, when the inclination angle of the neck reduced diameter portion and the bulging portion enlarged diameter portion with respect to the can shaft exceeds 24 °, the can shaft of the load acting when the neck portion is reduced in diameter or the bulging portion is expanded in diameter. The directional component cannot be made sufficiently small, which may lead to buckling. Similarly, the amount of contraction of the outer diameter in the radial direction with respect to the can shaft from the upper end of the shoulder to the minimum contraction position of the neck contraction portion and the diameter direction with respect to the can shaft from the upper end of the neck to the maximum bulge position of the bulge. Even if the amount of expansion of the inner diameter exceeds 2.2 mm, the molding load becomes large and buckling may occur in the thin-walled bottomed cylindrical body as described above. On the other hand, if the inclination angle is less than 18 °, or if the amount of reduction of the outer diameter or the amount of expansion of the inner diameter is less than 0.5 mm, the required inclination angle or outer diameter of the neck or bulge can be formed. It may disappear.

The metal plate formed on the main body of such a bottle can via a bottomed cylinder is an aluminum alloy of A3004 or A3104 in JIS H 4000, and is 0.2 at 205 ° C. × 20 minutes after baking. It is desirable that the% proof stress is in ^{the range of 235 N / mm 2 to} 265 N / mm ^2. If the proof stress after baking is less ^{than 235 N / mm 2} , the bottomed cylindrical body may buckle during molding of the neck and bulge even if the inclination angle and the outer diameter expansion / contraction amount are as described above. On the contrary, even if the proof stress after baking ^{exceeds 265 N / mm 2} , the load required for molding becomes large and the load control may become difficult.

As described above, according to the present invention, it is possible to prevent buckling of the bottomed cylindrical body when molding the neck portion and the bulging portion, and the production yield and production efficiency of the bottle can due to such buckling can be prevented. It is possible to further reduce the thickness of the can body of the bottle can and promote further resource saving and energy saving while preventing such deterioration.

It is a partially broken side view of the bottle can manufactured by one Embodiment of this invention. It is a flowchart which shows one Embodiment of this invention. In the bottleneck molding step according to the embodiment of the present invention, (a) a cross-sectional view showing a bottomed cylindrical body before the neck portion is molded, (b) a cross-sectional view showing a mold for molding the neck portion, and (c) FIG. It is an enlarged cross-sectional view which shows the periphery of the neck part molding part of the mold shown in b). It is sectional drawing which shows the bottomed cylinder formed by the bottleneck molding process of one Embodiment of this invention. In the cap mounting portion forming step according to the embodiment of the present invention, (a) a cross-sectional view showing a bottomed cylinder before the bulging portion is formed, and (b) a sectional view showing a diameter-expanding tool for forming the bulging portion. , (C) is an enlarged cross-sectional view showing the periphery of the enlarged diameter portion of the diameter-expanding tool shown in FIG. It is sectional drawing which shows the bottomed cylindrical body molded by the cap attachment part molding process of one Embodiment of this invention.

FIG. 1 shows a can body 1 of a bottle can manufactured according to an embodiment of the present invention, and FIGS. 2 to 6 show an embodiment of the present invention for manufacturing such a can body 1. Is shown. As shown in FIG. 1, the bottle can manufactured by the present embodiment is formed integrally with the bottom portion 2 and the bottom portion 2, and the can body 1 is formed integrally with the bottom portion 2 from the outer peripheral edge to the upper end side (upper side in FIG. 1). It is provided with an outer peripheral portion 3 extending to the upper end side, and has a substantially multi-stage bottomed cylindrical shape centered on a can shaft C whose diameter is reduced toward the upper end side.

A dome portion 2a having a substantially arcuate cross section recessed inward in the can axis C direction (upper end side of the can body 1) is formed in the center of the bottom portion 2, and the outer periphery of the dome portion 2a is formed in the can axis C direction. The annular convex portion 2b projecting to the outside (lower end side of the can body 1) is continuously formed in the circumferential direction around the can axis C. Further, the outer peripheral portion 3 has a cylindrical body portion 5 centered on the can shaft C in order from the bottom portion 2 toward the opening 4 on the upper end side of the can body 1, and gradually has a constant inclination toward the upper end side. This embodiment also has a conical pedestal-shaped shoulder portion 6 with a reduced diameter, a tubular neck portion 7 extending from the shoulder portion 6 toward the upper end side, and a bulging portion 8 on the lower end side. Is formed with a cap mounting portion 9 that has been threaded.

In one embodiment of the method for manufacturing a bottle can of the present invention for manufacturing such a bottle can, as shown in the flowchart of FIG. 2, first, a metal plate such as an aluminum alloy is formed into a disk in a cupping press step by a cupping press machine. A cup-shaped material with a shallow depth is manufactured by punching it into a shape and drawing, and this cup-shaped material is re-squeezed and ironed in the DI pressing process using a DI press machine to be stretched in the can axis C direction. A bottomed cylindrical body (DI can) in which the dome portion 2a and the annular convex portion 2b are formed on the bottom portion 2 is formed.

Here, the metal plate formed into the cup-shaped material in the cupping press process is an aluminum alloy of A3004 or A3104 in JIS H 4000 in the present embodiment, and has a 0.2% proof stress after baking at 205 ° C. for 20 minutes. Those in the range of 235 N / mm ^{2 to} 265 N / mm ^{2 are used.} Further, in the bottomed cylindrical body formed from this cup-shaped material, a cylindrical portion centered on the can shaft C is formed on the outer peripheral portion, and the outer diameter of this cylindrical portion is outside the body portion 5 of the can body 1. It has a constant outer diameter that is approximately equal to the diameter. However, the thickness of the upper end side portion of this cylindrical portion is in the range of 0.180 mm to 0.225 mm, while the thickness of the lower end side portion is extremely slightly thinner than the upper end side portion.

The bottomed cylinder thus formed is washed and dried in the first washing step, and then the inner and outer surfaces are painted and baked in the painting step. Then, in the bottomed cylindrical body that has been painted, the lower end side of the upper end side portion of the cylindrical portion is reduced in diameter by a mold in the bottleneck molding step by the bottle necker, and the shoulder portion 6 and the neck portion 7 are molded, and then the shoulder portion 6 and the neck portion 7 are formed. In the cap mounting portion molding process using the same bottlenecker, the upper end side of the neck portion 7 is enlarged by a diameter-expanding tool to form the bulging portion 8, and the thread cutting process or the like is further performed on the upper end side of the bulging portion 8. The cap attachment portion 9 is formed by the application, and is formed into a can body 1 of a bottle can as shown in FIG.

The can body 1 thus formed is washed and dried by the second washing step, and then inspected for the presence or absence of pinholes, foreign matter adhesion on the outer surface, scratches, stains, printing defects, etc. in the inspection step, and is inspected at a beverage factory or the like. After being filled with the contents such as beverages, a cap (not shown) is attached to the cap attachment portion 9, the cap is sealed, and the product is shipped. During or during each of the above steps, trimming is performed to cut the upper end edge of the bottomed cylindrical body, and bottom reform is performed to reshape the cross-sectional shape of the annular convex portion 2b at the bottom, if necessary.

Here, in the bottleneck molding process by the bottle necker, in the molding of the shoulder portion 6, a plurality of cylindrical molds having an inner diameter gradually decreasing are formed, and the cylindrical portion of the bottomed cylindrical body is formed in order from the one having the largest inner diameter. By press-fitting into the upper end side portion of the cylinder and plastically deforming it, the lower end side portion of the upper end side portion of the cylindrical portion is inclined toward the upper end side in a stepwise manner toward the inner peripheral side, and this inclination is achieved. This is done by gradually reducing the inner peripheral side of the lower end side into a cylindrical shape with a smaller inner diameter.

FIG. 3A shows a bottomed cylindrical body 10A for which molding of the shoulder portion 6 has been completed in the bottleneck molding step, and a can shaft C is provided on the upper end side of the inner peripheral portion of the shoulder portion 6. A cylindrical portion 11A whose diameter is reduced as the center is formed. Further, FIG. 3B shows a mold 21 for forming the neck portion 7 on the cylindrical portion 11A of the bottomed cylindrical body 10A, and the mold 21 has a substantially cylindrical shape coaxial with the can shaft C. The inner peripheral portion thereof has a large-diameter cylindrical portion 22 centered on the can shaft C in order from the lower end side to the upper end side, and a concave portion that inclines toward the upper end side toward the inner peripheral side. A conical base surface-shaped portion 23, a neck molding portion 24, and a small-diameter cylindrical portion 25 are formed.

The large-diameter cylindrical portion 22 has an inner diameter into which the outer peripheral surface of the cylindrical portion (body portion 5 of the can body 1) of the bottomed cylindrical body 10A can be fitted, and the concave conical base surface portion 23 has a bottomed cylinder. It is inclined toward the upper end side toward the inner peripheral side with a larger inclination with respect to the can shaft C than the shoulder portion 6 of the body 10A. Further, the small-diameter cylindrical portion 25 has an inner diameter slightly smaller than the outer diameter of the cylindrical portion 11A of the bottomed cylindrical body 10A.

Further, the neck forming portion 24 is in order from the lower end side to the upper end side, and as shown in an enlarged cross section along the can shaft C in FIG. 3C, a convex arc in contact with the upper end of the concave conical base surface portion 23. The first convex curved portion 24a forming the above, a short linear annular portion 24b that is in contact with the upper end of the first convex curved portion 24a and extends substantially parallel to the upper end side of the can shaft C, and the annular portion 24b. A concave portion 24c that is in contact with the upper end of the first convex portion 24a and forms a concave arc or the like having a larger radius than the first convex curved portion 24a, and a can that is in contact with the upper end of the concave curved portion 24c and is directed toward the inner peripheral side toward the upper end side. An inclined portion 24d that is inclined with respect to the axis C and has a linear shape longer than the annular portion 24b, and a second convex curved portion that forms a convex arc or the like in contact with the upper end of the inclined portion 24d and the lower end of the small-diameter cylindrical portion 25. It is equipped with 24e.

Here, the inner diameter of the annular portion 24b is set to a size that allows the cylindrical portion 11A of the bottomed cylindrical body 10A for which the molding of the shoulder portion 6 has been completed to be fitted. Therefore, when such a mold 21 is inserted coaxially with the can shaft C from the upper end side of the bottomed cylindrical body 10A after the molding of the shoulder portion 6 is completed as shown by the white arrow in FIG. 3, the cylindrical portion is formed. The diameter of 11A is reduced along the concave portion 24c and the inclined portion 24d while sliding contact with the inner peripheral surface of the annular portion 24b from the upper end side.

Then, when the upper end position of the concave conical base surface portion 23 coincides with the upper end position of the shoulder portion 6 in the can axis C direction and the mold 21 reaches the stroke end (bottom dead point), the upper end side of the cylindrical portion 11A The portion is narrowed down to an outer diameter substantially equal to the inner diameter of the small-diameter cylindrical portion 25 and reduced in diameter, and the cross-sectional shape of the neck molded portion 24 is reduced from the lower end side portion of the reduced diameter cylindrical portion 11A to the shoulder portion 6. The neck portion 7 having a cross-sectional shape of an outer peripheral surface as if substantially transferred is formed. As a result, the bottomed cylinder 10A shown in FIG. 3A is formed into the bottomed cylinder 10B as shown in FIG.

In the neck portion 7 of the bottomed cylindrical body 10B formed in this way, the cylindrical portion 11A having a diameter before being reduced to the shoulder portion 6 side of the neck portion 7 by the annular portion 24b of the mold 21 is small. On the upper end side thereof, the concave diameter portion 7a of the neck molding portion 24 is formed by the inclined portion 24d from the concave portion 24c of the neck molding portion 24 to reduce the diameter toward the upper end side. The inclination angle α with respect to the can shaft C of the conical pedestal-shaped portion on the upper end side formed by the inclined portion 24d of the neck reduced diameter portion 7a is in the range of 18 ° to 24 °. It is said to be 24 °. Therefore, in the present embodiment, the inclination angle α formed by the cross section of the inclined portion 24d in the neck forming portion 24 of the mold 21 shown in FIG. 3C with respect to the can axis C is also in the range of 18 ° to 24 °. It is set to 24 °.

Further, the amount of diameter reduction from the upper end of the shoulder portion 6 to the minimum diameter reduction position of the neck diameter reduction portion 7a (in the present embodiment, the position of the cylindrical portion 11B reduced in diameter by the small diameter cylindrical portion 25 of the mold 21) is , The amount of molding of the neck portion 7 by the neck molding portion 24. Then, the amount of diameter reduction in the outer diameter in the radial direction with respect to the can shaft C from the upper end of the shoulder portion 6 to the minimum diameter reduction position of the neck portion diameter reduction portion 7a, that is, the cylindrical shape before the diameter reduction left on the shoulder portion 6 side. The difference d1-d2 between the diameter (outer diameter) d1 of the portion 11A and the diameter (outer diameter) d2 of the reduced diameter cylindrical portion 11B on the upper end side of the neck reduced diameter portion 7a is 0.5 mm to 2.2 mm. It is said to be in the range of. Therefore, the difference d1-d2 between the diameter (inner diameter) d1 of the annular portion 24b and the diameter (inner diameter) d2 of the small-diameter cylindrical portion 25 in the neck forming portion 24 of the mold 21 shown in FIG. Is in the range of 0.5 mm to 2.2 mm.

Next, in the cap attachment portion forming step, the cylindrical portion 11B whose diameter is reduced by the mold 21 of the bottomed cylindrical body 10B shown in FIGS. 4 and 5A in which the neck portion 7 is formed is shown in FIG. The diameter-expanding tool 31 as shown in b) is inserted, and the bulging portion 8 is formed on the upper end side of the neck portion 7. The diameter-expanding tool 31 has a cylindrical shape with a two-stage outer diameter, and the outer diameter of the small diameter portion 32 on the lower end side is set to a size that can be fitted to the inner circumference of the reduced diameter cylindrical portion 11B. The outer diameter of the large diameter portion 33 on the upper end side is slightly larger than the inner diameter of the reduced diameter cylindrical portion 11B, and is also arranged coaxially with the can shaft C.

Further, between the small diameter portion 32 and the large diameter portion 33, as shown in an enlarged cross section along the can shaft C in FIG. 5 (c), the distance is constant toward the outer peripheral side toward the upper end side. A diameter-expanded portion 34 that expands in diameter by inclination is formed. The enlarged diameter portion 34 is in contact with the small diameter portion 32 via a concave curved portion 34a having a concave arc in cross section, and the large diameter portion 33 has a convex portion such as a convex arc in cross section having a radius larger than that of the concave portion 34a. It is formed in a straight cross section that is in contact with each other via 34b.

When such a diameter-expanding tool 31 is inserted into the inner circumference of the cylindrical portion 11B whose diameter is reduced coaxially with the can shaft C as shown by the white arrow in FIG. 5, the diameter-expanding portion 32 is slidably contacted. The diameter of the cylindrical portion 11B is expanded from the upper end side by the portion where the large diameter portion 33 is formed from 34. In the present embodiment, the upper end of the small diameter portion 32 of the diameter expansion tool 31 inserted in this manner is arranged at a position slightly spaced from the upper end of the neck reduced diameter portion 7a of the neck portion 7 toward the upper end side in the can axis C direction. At this point, the diameter-expanding tool 31 reaches the stroke end (bottom dead point), and a reduced-diameter cylindrical portion 11B is left on the neck portion 7 on the upper end side of the neck-reduced diameter portion 7a, and the upper end is connected to the upper end side thereof. A bulging portion 8 whose diameter increases toward the side is formed, and the upper end side of the bulging portion 8 is a cylindrical portion 11C whose diameter is expanded by the large diameter portion 33. As a result, the bottomed cylinder 10B shown in FIGS. 4 and 5A is formed into the bottomed cylinder 10C as shown in FIG.

Then, the can shaft of the bulging portion expanding portion 8a whose diameter is expanded from the upper end of the neck portion 7 of the bulging portion 8 thus expanded (in the present embodiment, the reduced diameter cylindrical portion left in the neck portion 7). The inclination angle β with respect to C is in the range of 18 ° to 24 °, which is the same as the inclination angle α, and is 20 ° in the present embodiment. Therefore, the inclination angle β formed by the diameter-expanding portion 34 of the diameter-expanding tool 31 shown in FIG. 5C with respect to the can shaft C is also in the range of 18 ° to 24 °, and is 20 ° in the present embodiment. ..

Further, the amount of diameter expansion from the upper end of the neck portion 7 which is the reduced diameter cylindrical portion 11B to the maximum bulging position of the bulging portion 8 (in the present embodiment, the expanded cylindrical portion 11C in FIG. 6) is the diameter expansion. This is the molding amount of the bulging portion 8 by the tool 31. Then, the amount of expansion of the inner diameter in the radial direction with respect to the can shaft C from the upper end of the neck portion 7 to the maximum bulging position of the bulging portion 8, that is, the diameter (inner diameter) of the outer peripheral surface at the maximum bulging position of the bulging portion 8. The difference d3-d4 between d3 and the diameter (inner diameter) d4 at the upper end of the neck portion 7 is in the range of 0.5 mm to 2.2 mm, which is the same as the diameter reduction amount. Therefore, the difference d3-d4 between the diameter (outer diameter) d3 of the large diameter portion 33 and the diameter (outer diameter) d4 of the small diameter portion 32 in the diameter expansion tool 31 shown in FIG. 5 (c) is also 0.5 mm to 2. The range is 2 mm.

In this way, the bulging portion 8 is formed on the upper end side of the neck portion 7, and the bottomed cylindrical body 10C having the cylindrical portion 11C whose diameter is expanded on the upper end side of the bulging portion 8 is the expanded cylinder. As described above, the upper end side of the shaped portion 11C is threaded to form the cap mounting portion 9 and the diameter is reduced, and the bulging portion 8 is left on the lower end side without being reduced in diameter. Further, a curl portion is formed in the opening 4 of the cap mounting portion 9, and the cap body 1 is formed into a bottle can body 1 as shown in FIG.

In such a method for manufacturing a bottle can, the inclination angle α of the neck reduced diameter portion 7a of the neck portion 7 formed in the bottleneck molding step with respect to the can shaft C and the bulging portion 8 formed in the cap mounting portion molding step The inclination angle β of the bulging portion enlarged diameter portion 8a with respect to the can shaft C is set to be a shallow angle with respect to the can shaft C in the range of 18 ° to 24 °. Therefore, by inserting the mold 21 and the diameter-expanding tool 31 into the cylindrical portions 11A and 11B of the bottomed cylindrical bodies 10A and 10B, the diameters of the cylindrical portions 11A and 11B can be reduced or expanded to increase the diameter of the neck portion. The load in the can shaft C direction acting on the bottomed cylindrical bodies 10A and 10B when the 7 and the bulging portion 8 are formed can be reduced.

Further, the amount of diameter reduction d1-d2 of the outer diameter in the radial direction with respect to the can shaft C from the upper end of the shoulder portion 6 to the minimum diameter reduction position of the neck portion diameter reduction portion 7a in the bottleneck molding process, and the neck portion in the cap mounting portion molding process. The diameter expansion amount d3-d4 of the inner diameter in the radial direction with respect to the can shaft C from the upper end of 7 to the maximum bulging position of the bulging portion 8 is also small in the range of 0.5 mm to 2.2 mm, that is, the neck portion. The amount of molding of 7 and the bulging portion 8 in the diameter direction with respect to the can shaft C is small. Therefore, it is possible to suppress the load acting on the bottomed cylindrical bodies 10A and 10B when the neck portion 7 and the bulging portion 8 are formed.

Therefore, according to such a method for manufacturing a bottle can, the thickness of the metal plate formed into the cup-shaped material in the cupping press process is as thin as 0.230 mm to 0.300 mm, and therefore the DI press process is performed from this cup-shaped material. The thickness of the upper end side portion of the cylindrical portion of the bottomed cylindrical body formed in 1 is as thin as 0.180 mm to 0.225 mm, and the thickness of the lower end side cylinder portion of the upper end side portion is smaller than that of the upper end side portion. Even if it is thinner, buckling occurs in the bottomed cylinders 10A and 10B due to the load in the can axis C direction during the molding of the neck portion 7 in the bottleneck molding process and the molding of the bulging portion 8 in the cap mounting portion molding process. Can be prevented. Therefore, it is possible to further reduce the wall thickness without lowering the production yield and production efficiency of the bottle can, and it is possible to further promote resource saving and energy saving.

Here, if the inclination angle α of the neck reduced diameter portion 7a with respect to the can shaft C and the inclination angle β of the bulging portion enlarged diameter portion 8a with respect to the can shaft C are larger than 24 °, the neck portion is formed by the mold 21 or the diameter expanding tool 31. The component of the load acting when forming the reduced diameter portion 7a and the enlarged diameter portion 8a in the can axis C direction could not be sufficiently reduced, and the bottomed cylindrical bodies 10A and 10B were made particularly thin. There is a risk of buckling at the lower end of the cylindrical portion. On the other hand, when these inclination angles α and β are less than 18 °, the inclined portion 24d in the neck forming portion 24 of the mold 21 and the enlarged diameter portion 34 of the diameter-expanding tool 31 become close to parallel to the can shaft C, and the neck portion. It may be difficult to stably mold the reduced diameter portion 7a and the enlarged diameter portion 8a of the bulging portion with good reproducibility.

Further, the diameter reduction amount d1-d2 of the outer diameter in the radial direction with respect to the can shaft C from the upper end of the shoulder portion 6 to the minimum diameter reduction position of the neck diameter reduction portion 7a, and the maximum bulge of the bulging portion 8 from the upper end of the neck portion 7. Even when the diameter expansion amount d3-d4 of the inner diameter in the radial direction with respect to the can shaft C up to the ejection position is larger than 2.2 mm, there is a possibility that buckling cannot be reliably prevented because the molding amount itself becomes large. On the other hand, even when the diameter reduction amount d1-d2 and the diameter expansion amount d3-d4 are smaller than 0.5 mm, the neck diameter reduction portion 7a and the bulging portion diameter expansion portion 8a can be molded reliably and stably. It can be difficult.

In the present embodiment, both the inclination angles α and β of the neck reduced diameter portion 7a in the neck portion 7 and the bulging portion enlarged diameter portion 8a in the bulging portion 8 with respect to the can shaft C are in the range of 18 ° to 24 °. At the same time, the diameter reduction amount d1-d2 of the outer diameter in the radial direction with respect to the can shaft C from the upper end of the shoulder portion 6 to the minimum diameter reduction position of the neck diameter reduction portion 7a and the maximum bulge of the bulge portion 8 from the upper end of the neck portion 7. The diameter expansion amount d3-d4 of the inner diameter in the radial direction with respect to the can shaft C to the position is also set to be in the range of 0.5 mm to 2.2 mm, but the inclination angle α and the diameter reduction amount d1-d2. If is within the above range, at least one of the inclination angle β and the diameter expansion amount d3-d4 may be outside the above range, and if the inclination angle β and the diameter expansion amount d3-d4 are within the above range, the inclination angle α And at least one of the reduced diameter amounts d1-d2 may be outside the above range. However, it is of course desirable that both are in the above range as in the present embodiment.

Further, in the present embodiment, the metal plate formed into a cup-shaped material in the cupping press process and formed into a bottomed cylinder in the DI press process is an aluminum alloy of A3004 or A3104 in JIS H 4000 at 205 ° C. × 0.2% strength after baking for 20 minutes is in ^{the range of 235 N / mm 2 to} 265 N / mm ² , and the bottomed cylinders 10A and 10B in the bottleneck molding process and the cap mounting part molding process are used. It is possible to perform molding without applying an unnecessarily large load while more reliably preventing buckling.

That is, when the 0.2% proof stress of this metal plate after baking at 205 ° C. for 20 minutes is less ^{than 235 N / mm 2} , the inclination angles α and β, the reduced diameter amount d1-d2, and the expanded diameter amount d3- Even if d4 is used, buckling may easily occur in the bottomed cylindrical bodies 10A and 10B, and conversely, ^{even if the 0.2% proof stress after baking at 205 ° C. × 20 minutes exceeds 265 N / mm 2} , it is necessary for molding. The load becomes large, it becomes difficult to control the load, and there is a possibility that buckling is likely to occur.

Next, the effect of the present invention will be described with reference to examples of the present invention. In this embodiment, the aluminum alloy of A3104 in JIS H 4000 has a 0.2% proof stress of 254.8 N / mm ² after baking at 205 ° C. for 20 minutes, and a metal plate having a plate thickness of 0.300 mm is used in the cupping press process. The cup-shaped material was formed, and the bottomed cylindrical body was further formed in the DI pressing process.

Next, after the shoulder portion 6 is molded into the bottomed cylindrical body in the bottleneck molding step, the tilt angle α of the tilt portion 24d of the neck molding portion 24 with respect to the can axis C is in the range of 18 ° to 24 °, and the diameter is reduced. A neck portion 7 having a neck diameter reduced portion 7a is molded using six different types of dies 21 having an amount d1-d2 in the range of 0.5 mm to 2.2 mm, and the molding load at that time is measured. The presence or absence of buckling was confirmed. These are referred to as Examples 1 to 6.

Further, as a comparative example with respect to Examples 1 to 6, the inclination angle α of the inclined portion 24d in the neck molded portion 24 is 18 ° as in Examples 1 and 2, but the diameter reduction amount is larger than 2.2 mm. The mold having a diameter of 2.6 mm and the diameter reduction amount are 2.2 mm as in Examples 2, 4 and 6, while the mold having an inclination angle α of 26 °, which is larger than 24 °, also has a shoulder portion. The neck portion 7 was formed on the bottomed cylindrical body 10A formed by molding 6, and the forming load at that time was measured and the presence or absence of buckling was confirmed. These are referred to as Comparative Examples 1 and 2 in order.

The bottomed cylindrical body formed in the DI press step has a diameter of the cylindrical portion (diameter of the body portion 5 of the can body 1) of about 66 mm, and the thickness of the upper end side portion of the cylindrical portion is the thickness of the first embodiment. ~ 6 and Comparative Examples 1 and 2 were both in the range of 0.180 mm to 0.225 mm. Further, the bottomed cylinder 10A shown in FIG. 3A in which the shoulder portion 6 is formed on the bottomed cylinder in the bottleneck molding step is in the can axis C direction from the lower end of the bottom portion 2 to the upper end of the cylindrical portion. The height is 137 mm, the height from the lower end of the bottom 2 to the upper end of the shoulder 6 in the can axis C direction is 105 mm, and the diameter (outer diameter) of the reduced cylindrical portion 11A formed on the upper end side of the shoulder 6. ) Was 38 mm.

For Examples 1 to 6 and Comparative Examples 1 and 2, the thickness t (mm) of the upper end side portion of the cylindrical portion, the inclination angle α (°), the reduced diameter amount d1-d2 (mm), and the molding load F. (N) and the evaluation are summarized in Table 1 below. In the evaluation, those having a molding load F of less than 1000 N were double circles, those having a molding load of less than 2000 N were circles, those having a molding load of less than 2300 N were triangular, and those having a molding load of 2300 N or more were X.

From the results in Table 1, in Comparative Example 1 in which the diameter reduction amount is larger than 2.2 mm and Comparative Example 2 in which the inclination angle α is larger than 24 °, the molding load F is 2400 N or more, and the bottle necker is actually used. Buckling frequently occurred in the cylindrical portion of the bottomed cylindrical body 10A even when the neck portion 7 was formed. On the other hand, in Examples 1 to 6, the forming load F is suppressed to less than 2000N and buckling does not occur, and in particular, in Example 1 where the inclination angle α and the diameter reduction amount d1-d2 are the smallest, the forming load Buckling may occur even if F is 700 N, which is less than 1000 N, and the thickness t of the upper end side portion of the cylindrical portion of the bottomed cylinder before the shoulder portion 6 is formed is 0.180 mm, which is the thinnest. There wasn't.

1 Can body 2 Bottom part 3 Outer part 4 Opening part 5 Body part 6 Shoulder part 7 Neck part 7a Neck part Diameter reduction part 8 Swelling part 8a Swelling part Diameter expansion part 9 Cap mounting part 10A to 10C Bottomed cylinder 11A to 11C Cylindrical Shape 21 Mold 24 Neck molding 24d Inclined part 31 Diameter-expanding tool 34 Diameter-expanding part C Can shaft α Inclination angle of neck-reduced part 7a with respect to can-axis C β Sloping part Inclination of enlarged-diameter part 8a with respect to can-axis C Angle d1 Outer diameter in the radial direction with respect to the can shaft C at the upper end of the shoulder portion 6 (diameter of the cylindrical portion 11A before diameter reduction)
d2 Outer diameter in the radial direction with respect to the can shaft C at the minimum reduced diameter position of the neck reduced diameter portion 7a (diameter of the reduced diameter cylindrical portion 11B)
d3 Inner diameter in the radial direction with respect to the can shaft C at the maximum bulging position of the bulging portion 8 (diameter of the expanded cylindrical portion 11C)
d4 Inner diameter in the radial direction with respect to the can shaft C at the upper end of the neck portion 7 (diameter of the cylindrical portion 11B before diameter expansion)

Claims (3)

On the outer peripheral portion that is integrally molded with the bottom of the can body, a cylindrical body centered on the can shaft in order from the bottom to the upper end opening of the can body, and a shoulder that shrinks in diameter toward the upper end side. A method for manufacturing a bottle can in which a portion, a neck portion extending from the shoulder portion toward the upper end side, and a cap mounting portion are formed.
Subjected to redraw and ironing and bottom formed into a cup-like material which is formed by deep drawing from a metal sheet having a thickness of 0.230Mm～0.300Mm, and the bottom, with the same outer diameter and the barrel, the A cylindrical portion in which the thickness of the shoulder portion, the neck portion, and the upper end side portion serving as the cap mounting portion is 0.180 mm to 0.225 mm, and the thickness of the lower end side portion serving as the body portion is thinner than the upper end side portion. DI press process to form the bottomed cylindrical body on which
A bottleneck molding step of forming the shoulder portion and the neck portion whose diameter is further reduced toward the upper end side from the shoulder portion by reducing the diameter of the upper end side portion of the bottomed cylinder.
A cap mounting portion molding step for molding the cap mounting portion is provided at the upper end portion of the neck portion.
In the bottleneck molding step, the inclination angle of the neck diameter-reduced portion that is reduced in the neck portion with respect to the can shaft is formed in the range of 18 ° to 24 °, and the neck diameter-reduced portion is formed from the upper end of the shoulder portion. A method for manufacturing a bottle can, wherein the amount of reduction in the outer diameter in the radial direction with respect to the can shaft up to the minimum diameter reduction position is in the range of 0.5 mm to 2.2 mm. On the outer peripheral portion that is integrally molded with the bottom of the can body, a cylindrical body centered on the can shaft in order from the bottom to the upper end opening of the can body, and a shoulder that shrinks in diameter toward the upper end side. A method for manufacturing a bottle can in which a portion, a neck portion extending from the shoulder portion toward the upper end side, and a cap mounting portion are formed.
Subjected to redraw and ironing and bottom formed into a cup-like material which is formed by deep drawing from a metal sheet having a thickness of 0.230Mm～0.300Mm, and the bottom, with the same outer diameter and the barrel, the A cylindrical portion in which the thickness of the shoulder portion, the neck portion, and the upper end side portion serving as the cap mounting portion is 0.180 mm to 0.225 mm, and the thickness of the lower end side portion serving as the body portion is thinner than the upper end side portion. DI press process to form the bottomed cylindrical body on which
A bottleneck molding step in which the upper end side portion of the bottomed cylinder is reduced in diameter to form the shoulder portion and the neck portion.
The upper end portion of the neck portion is provided with a cap mounting portion molding step of molding the cap mounting portion via a bulging portion that bulges toward the outer peripheral side.
In the cap mounting portion molding step, the inclination angle of the bulging portion diameter-expanded portion that expands from the upper end of the neck portion in the bulging portion with respect to the can shaft is formed in the range of 18 ° to 24 °, and the neck portion is formed. A method for manufacturing a bottle can, wherein the amount of expansion of the inner diameter in the radial direction with respect to the can shaft from the upper end of the can to the maximum bulging position of the bulging portion is in the range of 0.5 mm to 2.2 mm. The metal plate is an aluminum alloy of A3004 or A3104 in JIS H 4000, and is characterized in that the 0.2% proof stress after baking at 205 ° C. × 20 minutes is in the range of ^{235 N / mm 2 to} 265 N / mm ^2. The method for producing a bottle can according to claim 1 or 2.

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