JP7072380B2 - How to make a bottle can - Google Patents

Description

In the present invention, a shoulder portion, a neck portion, and a cap mounting portion are molded in a bottleneck molding step on a portion opposite to the bottom portion of the cylindrical portion of a bottomed cylinder having a bottom portion and a cylindrical portion molded in the DI press process. It relates to a method of manufacturing a bottle can having a molded can body.

As a method for manufacturing such a bottle can, for example, in Patent Document 1, at a stage of forming a can body made of metal (aluminum alloy), the can body has a bottom portion, and the bottom portion follows the lower portion of the side wall. The side wall is squeezed and squeezed to the wall to continue to the wall, the wall continues to the open upper end, and the wall of the can body is thicker than the bottom of the side wall. The stage of forming the can and the stage of forming the truncated cone by applying necking processing to the wall multiple times. The truncated cone is thicker than the wall of the can body, and the upper part is formed. It has a neck with a diameter smaller than the diameter of the can body, and the neck forms a truncated conical part that continues to the cylindrical part near the upper end opening, and the stage of forming a bead on the top of the metal can. A manufacturing method including a step of forming a screw on a cylindrical portion below the bead and a step of forming an annular bead below the screw in order to fix the closure to the screw is described.

Here, in Patent Document 1, the typical drawn and ironed can body (DI can) used in the present invention has a metal thickness of about 0.34 mm in a bottom cross section and about a thin wall portion. It is stated that it may be 0.14 mm, and about 0.19 mm at the thick part, such a can body is about 76.2 mm in diameter and about 187 mm to hold 591 ml in height, or It is also stated that it may be about 216 mm to accommodate 887 ml.

Further, in Patent Document 1, the thickness of the metal of the other can body (DI can) for use in the invention is about 0.25 to 0.38 mm in the bottom cross section and about 0.11 in the thin wall portion. It is stated that it may be from 0.17 mm to 0.17 mm, and about 0.17 to 0.22 mm in thickened portions, such cans having a diameter of about 63.5 to 88.9 mm and a height of about. It is also stated that it may be 127 to 254 mm.

Japanese Unexamined Patent Publication No. 2006-02755

Here, the bottle can manufactured by the manufacturing method described in Patent Document 1 has a relatively large capacity as described above, but is an aluminum alloy for 310 ml that is generally distributed in Japan. A bottle can has a body diameter of about 66 mm and a can height of about 132.6 mm, and is a bottomed cylindrical body having a bottom and a cylinder used for manufacturing such a bottle can. (DI can) has a base plate thickness and a bottom thickness of about 0.345 mm, a wall portion which is a thin wall portion on the bottom side of the cylindrical portion has a thickness of about 0.135 mm, and a side opposite to the bottom portion of the cylindrical portion. The thickness of the flange portion, which is the thick portion of the above, is about 0.225 mm, the step between the flange portion and the wall portion is about 0.090 mm, and the mass is about 17.5 g.

Also, the 410 ml bottle cans that are also distributed in Japan have a body diameter of about 66 mm and a can height of about 164 mm, and are used for manufacturing the 410 ml bottle cans. The bottom cylinder has a base plate thickness and a bottom thickness of about 0.400 mm, a wall portion thickness of about 0.130 mm, a flange portion thickness of about 0.225 mm, and a step between the flange portion and the wall portion. It is about 0.095 mm and weighs about 21.0 g. In addition, in the case of bottle cans for beverages such as coffee, in order to enhance the aroma of the contents, the bulging part (annular bead) at the lower end of the cap mounting part corresponding to the cap with a diameter (nominal diameter which is an approximate numerical value) of 38 mm Most of the valleys between the neck and the valley have an outer diameter (diameter) of about 35.4 mm, but the valleys with a smaller outer diameter (diameter) of 33 mm are compatible with caps for ease of drinking. Bottle cans with an outer diameter of about 30.7 mm are also available.

By the way, in recent years, in such bottle cans, weight reduction of the can body is required in order to save resources in the metal material forming the can body and energy saving in material manufacturing, for example, 1 g lighter per can. Even if it can be made, it is possible to significantly save resources, save energy, or reduce the cost of the can itself with bottle cans that are distributed in a huge number on the market. Here, in order to reduce the weight of the can body, it is conceivable to reduce the thickness of the base plate of the metal plate formed on the can body to reduce the thickness of the bottom portion, the wall portion, and the flange portion.

However, simply by unnecessarily thinning the original plate thickness of the metal plate to thin the wall and flange parts, the metal plate can be re-squeezed into a cup-shaped material formed by drawing in the cupping press process and re-squeezed in the DI press process. When forming a bottomed cylinder by ironing, or in the bottleneck forming process on the flange of the bottomed cylinder thus formed, the shoulder (the truncated conical part), the neck, and the cap mounting part ( When forming the bead, screw, annular bead), the thinned wall portion may be particularly buckled or deformed. In particular, if the thickness of the flange portion is too thin, the cap mounting portion may be cracked in the bottleneck molding process.

Further, as described above, in the DI press process, a wall portion, which is a thin-walled portion, is formed on the bottom side of the cylindrical portion of the bottomed cylinder, and a flange portion, which is a thick-walled portion, is formed on the side opposite to the bottom portion. By forming a recess on the outer surface of the punch that performs the above-mentioned ironing process between a plurality of ironing dies in a DI press machine at a position corresponding to the flange portion of the bottomed cylinder, the flange portion is formed from the wall portion. Is also thick.

However, when the step between the flange portion and the wall portion becomes large due to the thinning, the punch removal property from the bottomed cylinder is impaired and a removal failure occurs, and the DI press machine is stopped and the bottomed cylinder fails to be removed. The body must be removed from the punch, which can significantly reduce the manufacturing efficiency and yield of bottle cans. Further, if this step is large, stress in the can axis direction due to the molding load is concentrated on the step portion in the DI pressing process or the bottleneck forming process, and buckling or deformation may occur.

Further, the upper end of the bottomed cylinder formed by the DI press process and the upper end of the can body in which the shoulder and the neck are formed in the bottleneck forming process of the bottomed cylinder are formed on the bottomed cylinder. In order to make the height and the can height of the can body uniform, trimming is performed by cutting the upper end portion of these with a predetermined trim allowance so as to be a constant height from the bottom portion.

However, in a metal plate with a thin original plate, if a bottomed cylinder is formed in the DI press process without balancing the thickness of the flange portion and the thickness of the wall portion, the bottomed cylinder or bottleneck forming process is performed. In the can body molded in the above, it is not possible to secure the necessary trim allowance at the upper end, and due to the lack of trim allowance, the bottomed cylinder and the can body cannot be made to a certain height and must be treated as defective products. You won't get it. Further, in order to solve such a shortage of trim allowance, there is a limit to increasing the area of the metal plate formed into a bottomed cylinder by, for example, a DI pressing process.

Furthermore, if the thickness of the flange is too thin, in the capping process of attaching the cap after filling the can body with beverages, etc., if capping is performed under the current capping conditions with a base plate thickness of 0.400 mm, the cap It has been found that the mounting portion may be deformed or buckled, and the resealing torque may increase when the cap once removed is screwed into the cap mounting portion again to reseal.

The present invention has been made under such a background, and even if the original plate thickness of the metal plate is reduced in order to reduce the weight of the can body, the seat in the DI pressing process, the bottleneck forming process, and the capping process. It is possible to mold the bottomed cylinder and the can body without causing bending or punch removal failure, insufficient height of the bottomed cylinder, insufficient trim allowance of the can body, deformation or buckling of the cap mounting part, etc. The purpose is to provide a method for manufacturing bottle cans that can promote resource saving, energy saving, reduction of carbon dioxide gas, and weight reduction of the can body.

Here, the inventor of the present invention has made extensive studies on bottle cans for 310 ml and 410 ml having an outer diameter (diameter) of about 30.7 mm in the valley portion corresponding to the cap having a diameter of 33 mm described above. When the original thickness of the metal plate is reduced in order to reduce the weight of the can body, the cup-shaped material formed by drawing in the cupping press process is re-squeezed and ironed in the DI press process. At the time of application, the thickness of the wall portion, which is the thin portion on the bottom side of the cylindrical portion, is 0.100 mm to 0.130 mm, and the thickness of the flange portion, which is the thick portion on the side opposite to the bottom portion of the cylindrical portion, is 0. By forming a bottomed cylinder with a step of 140 mm to 0.200 mm and a step between the flange portion and the wall portion of 0.090 mm or less, buckling and deformation in the DI pressing process, bottleneck forming process, and capping process can be achieved. It has been found that the can body of a bottle can of a predetermined can height can be efficiently molded without causing poor punch removal and insufficient trim allowance.

Therefore, in order to solve the above-mentioned problems and achieve the above-mentioned object based on such findings, the present invention first comprises a method for manufacturing a bottle can for producing a 310 ml bottle can, the original plate thickness. A cup-shaped material is formed from a metal plate having a 0.250 mm to 0.300 mm and 0.2% resistance of 235 N / mm ² to 265 N / mm ² by drawing in a cupping press process, and the cup-shaped material is formed into this cup-shaped material in the DI press process. After re-drawing and ironing, it has a bottom and a cylindrical portion, and the thickness of the wall portion, which is a thin wall portion on the bottom side of the cylindrical portion, is 0.100 mm to 0.130 mm. The thickness of the flange portion, which is the thick portion on the opposite side, is 0.140 mm to 0.200 mm, the length of the portion having the constant thickness of the flange portion in the can axis direction is 42 mm to 60 mm, and the flange portion. A bottomed cylinder having a step of 0.090 mm or less from the wall portion is formed, and in the bottleneck forming step on the flange portion of the bottomed cylinder, the cylindrical body portion is directed to the side opposite to the bottom portion. By forming a shoulder portion that shrinks in diameter according to the procedure and a cap mounting portion having a bulging portion that bulges toward the outer periphery at the lower end, a valley portion that is the minimum diameter portion between the bulging portion and the shoulder portion. The outer diameter (diameter) of the can is 28.7 mm to 32.7 mm, the can height from the bottom to the upper end of the cap mounting portion is 129.0 mm to 135.0 mm, and the diameter of the body is 64.24 mm to 68. It is characterized by producing a bottle can having a can body of 24 mm and a mass of 13.5 g to 16.0 g . The height of the can is preferably in the range of 131.6 mm to 133.6 mm.

Further, based on the same finding, the present invention secondly comprises a method for manufacturing a bottle can for 410 ml, which has a base plate thickness of 0.270 mm to 0.320 mm and a 0.2% resistance of 235 N / mm ² . A cup-shaped material is formed from a metal plate of ~ 265 N / mm ² by drawing in a cupping press process, and the cup-shaped material is re-drawn and ironed in a DI press process to have a bottom and a cylindrical portion. The thickness of the wall portion, which is the thin portion on the bottom side of the cylindrical portion, is 0.100 mm to 0.130 mm, and the thickness of the flange portion, which is the thick portion on the opposite side of the bottom portion of the cylindrical portion, is 0.140 mm or more. A bottomed cylinder is formed having a length of 0.200 mm, a portion having a constant thickness of the flange portion in the can axis direction of 42 mm to 60 mm, and a step difference between the flange portion and the wall portion of 0.090 mm or less. However, in the bottleneck forming step on the flange portion of the bottomed cylinder, a shoulder portion whose diameter is reduced from the cylindrical body portion toward the side opposite to the bottom portion, and a bulge that bulges toward the outer periphery at the lower end. By molding the cap mounting portion having the portion, the outer diameter (diameter) of the valley portion, which is the minimum diameter portion between the bulging portion and the shoulder portion, is 28.7 mm to 32.7 mm, from the bottom portion. A bottle can having a can body having a can height of 160.0 mm to 166.5 mm to the upper end of the cap mounting portion, a body diameter of 64.24 mm to 68.24 mm , and a mass of 16.5 g to 19.0 g . It is characterized by manufacturing. The height of the can is preferably in the range of 163.0 mm to 165.0 mm.

In the method for manufacturing the first and second bottle cans having such a configuration, the original plate thickness is 0.250 mm to 0.300 mm or 0.270 mm to 0.320 mm, which is thinner than the thin metal plate, respectively. By molding a bottomed cylinder in which the thickness in the range based on the above findings is given to the wall portion and the flange portion of the cylindrical portion in the DI pressing step, in this DI pressing step, the subsequent bottleneck forming step, and the capping step. A bottle with a can body having a can height of 129.0 mm to 135.0 mm for 310 ml and 160.0 mm to 166.5 mm for 410 ml without causing buckling, deformation, poor punch removal, insufficient trim allowance, etc. It becomes possible to manufacture cans.

That is, if the thickness of the wall portion is less than 0.100 mm or the thickness of the flange portion is less than 0.140 mm, the bottomed cylinder or the can body is buckled or deformed in the DI pressing process or the bottleneck forming process. , There is a risk of cracking. Further, if the thickness of the wall portion exceeds 0.130 mm or the thickness of the flange portion exceeds 0.200 mm, a bottomed cylinder or a can formed from a metal plate having a thin original plate thickness as described above. In the main body, the required can height cannot be obtained, resulting in a shortage of trim allowance.

Further, if the step between the flange portion and the wall portion exceeds 0.090 mm, poor punch removal may occur when a punch having a recess on the outer surface as described above is used in the DI pressing process. In the DI press process and the bottleneck forming process, stress due to the forming load is concentrated on the stepped portion, and there is a possibility that buckling or deformation may occur. In the method for manufacturing the first bottle can, it is desirable that the base thickness of the metal plate is in the range of 0.270 mm to 0.290 mm, and in the method for manufacturing the second bottle can, the metal is used. It is desirable that the original plate thickness of the plate is in the range of 0.290 mm to 0.310 mm.

Furthermore, the outer diameter (diameter) of the valley, which is the minimum diameter between the bulge at the lower end of the cap mounting portion corresponding to the cap with a diameter of 33 mm and the shoulder, is in the range of 28.7 mm to 32.7 mm. In a certain first and second method for manufacturing a bottle can, deformation and buckling of the cap mounting portion can be more reliably prevented, especially in the capping step. Here, in the capping process, the pressing force P toward the radial inward received by the valley portion when the hem winding portion (flare) at the lower end of the cap is wound around the valley portion by the hem winding roll of the capping device corresponds to this. The amount of deformation (change amount of radius) ΔR of the valley portion can be expressed by the following equation (1).

ΔR = R ² / (t × E) × P… (1)

In the above formula (1), P is the external pressure (pressure received by the valley from the hem winding roll inward in the radial direction), R is the outer diameter of the valley (however, the radius), and t is the thickness of the valley. (Thickness), E is the Young's modulus of the metal material of the bottle can. From the above equation (1), it can be seen that when the external pressure P, the thickness t, and the Young's modulus E are constant, the deformation amount ΔR of the valley portion is proportional to the square of the radius R of the valley portion. That is, if the radius R of the valley portion becomes smaller, the deformation amount ΔR of the valley portion also becomes smaller in proportion to the square of the radius R (actually, when the radius R changes, the thickness t also changes slightly. However, since it is a minute amount, it will not be considered here.)

Therefore, a bottle can with a valley outer diameter of about 30.7 mm corresponding to a 33 mm diameter cap is better than a bottle can with a valley outer diameter of about 35.4 mm corresponding to a cap with a diameter of 38 mm. Even if the pressing force received from the hem winding roll is the same as before, according to the above formula (1), the deformation amount ΔR of the valley portion is reduced by about 25%, so that the deformation of the cap mounting portion is prevented. To. Therefore, according to the present invention, even when the original plate thickness of the metal plate formed on the can body is reduced, the cap mounting portion is formed by the forming load (axial load or lateral load) at the time of capping. Deformation can be reliably prevented.

As described above, according to the present invention, in order to reduce the weight of a bottle can, even if the metal plate formed on the can body is made thinner, in the DI pressing process, the bottleneck forming process, and the capping process. It is possible to mold a can body of a predetermined can height without causing buckling or deformation of a bottomed cylinder or can body, insufficient trim allowance, or poor punch removal, resulting in significant resource saving, energy saving, and bottles. It is possible to promote the cost reduction of cans.

It is a partially broken side view of the can body of the bottle can manufactured in the 1st Embodiment of this invention. It is a partially broken side view of the upper end part of the can body shown in FIG. It is a partial schematic cross-sectional view of the bottomed cylinder formed in the can body shown in FIG. 1. It is a partially broken side view of the can body of the bottle can manufactured in the 2nd Embodiment of this invention. FIG. 4 is a partially broken side view of the upper end portion of the can body shown in FIG. It is a partial schematic cross-sectional view of the bottomed cylinder formed in the can body shown in FIG.

1, FIG. 2 and FIGS. 4 and 5 show partially broken side views of the can body 1 of the bottle can manufactured in the first and second embodiments of the present invention, respectively. FIG. 6 is a partial cross-sectional view showing an outline of the bottomed cylindrical body 11 formed on the can body 1 in the bottleneck forming step in the first and second embodiments. The bottle can shown in FIG. 1 has a capacity of 310 ml, and the bottle can shown in FIG. 4 has a capacity of 410 ml. In the can body 1 and the bottomed cylindrical body 11 in the first and second embodiments shown in FIGS. 1 to 6, the same reference numerals are given to the portions common to each other.

As shown in FIGS. 1 and 4, the can body 1 of the bottle can manufactured according to the present embodiment is integrally formed with the bottom portion 2 and the bottom portion 2, and is formed from the outer peripheral edge of the bottom portion 2 to the upper end side (FIGS. 1 and 4). In FIG. 4, it has a substantially multi-stage bottomed cylindrical shape centered on a can shaft C having an outer peripheral portion 3 extending to the upper 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. An annular convex portion 2b protruding outward (on the 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 with a constant inclination toward the upper end side. A conical pedestal-shaped shoulder portion 6 with a reduced diameter, a cylindrical neck portion 7 extending further toward the upper end side from the shoulder portion 6, and an annular valley portion 8a recessed from the upper end of the neck portion 7 toward the inner peripheral side of the can body 1. A bulging portion 8b projecting to the outer peripheral side with respect to the valley portion 8a, a cap mounting portion 8 having a screw portion 8c and a curl portion 8d arranged in order on the upper end side of the bulging portion 8b are formed. ing.

The can height H from the lower end edge of the bottom portion 2 of the can body 1 (the lower end edge of the annular convex portion 2b) to the upper end of the outer peripheral portion 3 (the upper end edge of the curl portion 8d) is the first bottle can for 310 ml. The can body 1 of the embodiment has 129.0 mm to 135.0 mm, preferably 131.6 mm to 133.6 mm, and the can body 1 of the second embodiment, which is a bottle can for 410 ml, has 160.0 mm to 166.5 mm. It is preferably 163.0 mm to 165.0 mm. Further, the diameter of the body portion 5 in the outer peripheral portion 3 of the can body 1 is 64.24 mm to 68.24 mm for both the bottle cans of the first and second embodiments.

In order to manufacture such a bottle can, first, in a cupping press process using a cupping press machine, a metal plate is punched into a disk shape and drawn to produce a cup-shaped material having a shallow depth. In the first embodiment, the metal plate formed into the cup-shaped material in this cupping press step has an original plate thickness of 0.250 mm to 0.300 mm, and in the second embodiment, the original plate thickness is 0.270 mm to 0. A 320 mm aluminum plate or an A3004 or A3104 aluminum alloy plate in JIS H 4000 having a 0.2% proof stress in the range of 235 N / mm ² to 265 N / mm ² after baking at 205 ° C. for 20 minutes is used. ..

Next, the cup-shaped material is re-squeezed and ironed in a DI pressing process using a DI press machine and stretched in the can shaft C direction to form a cylindrical portion 12 centered on the can shaft C on the outer peripheral portion. At the same time, a bottomed cylindrical body 11 as shown in FIGS. 3 and 6 in which a dome portion 2a and an annular convex portion 2b similar to those of the can body 1 are formed on the bottom portion 2 is formed. The thickness of the bottomed cylinder 11 and the bottom portion 2 of the can body 1 is substantially equal to the original plate thickness of the metal plate formed into the cup-shaped material in the cupping press process.

Further, the cylindrical portion 12 of the bottomed cylindrical body 11 has a constant outer diameter whose outer diameter (diameter) is substantially equal to the outer diameter of the body portion 5 of the can body 1. Further, the portion of the cylindrical portion 12 on the bottom 2 side is a wall portion 13 which is a thin portion having a reduced thickness (thickness), and the upper end side opposite to the bottom portion 2 (in FIGS. 3 and 6). The portion (upper side) is a flange portion 14 which is a thick portion having a thickness thicker than that of the wall portion 13. Here, in order to form the wall portion 13 and the flange portion 14 having different thicknesses in the cylindrical portion 12, the punch for which the ironing process is performed between the plurality of ironing dies in the DI press machine as described above is performed. A recess having a depth considering the difference in wall thickness may be formed at a position corresponding to the flange portion 14 on the outer surface.

The thickness of each of the wall portion 13 and the flange portion 14 is substantially constant, and the thickness of the wall portion 13 and the flange portion 14 gradually increases toward the upper end side of the bottomed cylinder 11. It is designed to be. However, for the sake of explanation in FIGS. 3 and 6, these thicknesses are drawn in a large ratio with respect to the height and the outer diameter of the bottomed cylinder 11. The length of the portion where the thickness of the flange portion 14 is constant in the can axis C direction is preferably in the range of 42 mm to 60 mm, and the bottomed cylindrical body 11 of the first and second embodiments. Both are said to be about 52 mm.

In the bottomed cylindrical body 11 shown in FIGS. 3 and 6, the thickness t1 of the wall portion 13 which is the thin portion of the cylindrical portion 12 is in the range of 0.100 mm to 0.130 mm, and the cylindrical portion is formed. Of the 12, the thickness t2 of the flange portion 14, which is the thick portion, is in the range of 0.140 mm to 0.200 mm. Further, the step t2-t1 between the flange portion 14 and the wall portion 13 is set to 0.090 mm or less. The step t2-t1 is preferably 0.070 mm or less, but is preferably 0.045 mm or more.

The bottomed cylindrical body 11 thus formed is washed and dried in the first washing step after the upper end edge of the cylindrical portion 12 is cut by a predetermined trim allowance and the heights are made uniform in the trimming step by the trimmer. Then, in the painting process, the inner and outer surfaces are painted and baked. Further, in the bottleneck forming process by the bottlenecker, the range of the flange portion 14 of the cylindrical portion 12 of the painted bottomed cylindrical body 11 is reduced in diameter, and the shoulder portion 6, the neck portion 7, and the outer diameter ( The valley portion 8a of the cap mounting portion 8 to which the hem winding portion (flare) of the cap having a diameter of 33 mm can be wound in the range of 28.7 mm to 32.7 mm in diameter) D is formed.

Next, the upper end side of the valley portion 8a is expanded in diameter to form the bulging portion 8b, and after the threaded portion 8c is formed on the upper end side of the bulging portion 8b, the upper end side of the screw portion 8c is on the outer peripheral side. The cap mounting portion 8 is formed by being folded back and curled to form the curl portion 8d, and becomes the can body 1 of the bottle can as shown in FIGS. 1 and 3. The outer diameter of the bulging portion 8b is in the range of 31.1 mm to 35.1 mm, and the outer diameter of the threaded portion 8c is in the range of 30.4 mm to 34.4 mm. Further, in this bottleneck molding step, trimming may be performed as necessary.

The can body 1 thus molded 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 then sent to a beverage factory or the like. After being transported and filled with contents such as beverages, a cap (not shown) is attached, sealed, and shipped. Note that bottom reform may be performed during or during the above-mentioned molding steps of the can body 1 to remold the cross-sectional shape of the annular convex portion 2b of the bottom portion 2, if necessary.

In the method for manufacturing a bottle can having such a configuration, in the bottomed cylindrical body 11 formed into the can body 1 in the bottleneck forming step, the thickness t1 of the wall portion 13 in the cylindrical portion 12 is 0.100 mm to 0.130 mm. The thickness t2 of the flange portion 14 is 0.140 mm to 0.200 mm, and the step t2-t1 between the flange portion 14 and the wall portion 13 is 0.090 mm or less. Based on this, as demonstrated in the examples described later, bottle cans for 310 ml and 410 ml can be used without buckling or deformation of the bottomed cylinder 11 or the can body 1, insufficient trim allowance, and poor punch removal. Can body 1 having a predetermined can height H can be formed in the above.

Therefore, even if the base plate thickness of the metal plate formed into the bottomed cylindrical body 11 is reduced as described above to reduce the weight of the bottle can, the yield of the bottle can is not reduced and the bottle can is reliable and efficient. Can be manufactured. Therefore, in the current situation where a huge number of bottle cans are distributed in the market, it is possible to significantly save resources and energy, and it is also possible to promote cost reduction of bottle cans.

Here, in the bottomed cylinder 11, if the thickness t1 of the wall portion 13 is less than 0.100 mm, the bottomed cylinder 11 may be buckled or deformed in the DI pressing process. Further, when the thickness t2 of the flange portion 14 of the bottomed cylindrical body 11 is less than 0.140 mm, the cap is used when molding the shoulder portion 6, the neck portion 7, and the cap mounting portion 8 in the bottleneck molding process, or in the capping process. When the can body 1 is wound and attached, buckling, deformation, cracking, etc. may occur in the can body 1. Even when the length of the portion where the thickness of the flange portion 14 is constant in the can axis C direction is less than 42 mm, the shoulder portion 6 is formed when the shoulder portion 6 is molded in the bottleneck molding step or in the capping step. May cause buckling or deformation.

Further, when the thickness t1 of the wall portion 13 exceeds 0.1 30 mm or the thickness t2 of the flange portion 14 exceeds 0.200 mm, the metal plate having a thin original plate thickness as described above is formed. In the bottomed cylindrical body 11, the height required in the DI pressing process cannot be obtained, resulting in a shortage of trim allowance, and even if the bottomed cylindrical body 11 is sent to the bottleneck forming process, the can body 1 having a predetermined can height H is formed. Can no longer be done. Further, when the thickness t2 of the flange portion 14 exceeds 0.200 mm, the molding load in the bottleneck molding step may increase even if the trim allowance is not insufficient.

Furthermore, if the step t2-t1 between the flange portion 14 and the wall portion 13 exceeds 0.090 mm, poor punch removal will occur when a punch having a recess on the outer surface as described above is used in the DI pressing process. This occurs, and the DI press machine must be stopped to remove the bottomed cylindrical body 11 that has failed to come off from the punch, which reduces the manufacturing efficiency and yield of bottle cans. Further, if the step t2-t1 is too large, stress due to the molding load is concentrated on the step portion in the DI pressing process or the bottleneck forming process, and the bottomed cylindrical body 11 or the can body 1 may buckle or deform. There is also.

Moreover, the outer diameter (diameter) D of the valley portion 8a, which is the minimum diameter portion between the bulging portion 8b at the lower end of the cap mounting portion 8 corresponding to the cap having a diameter of 33 mm and the shoulder portion 6, is 28.7 mm to 32. In the method for manufacturing a bottle can of the present embodiment, which has a diameter of 7 mm, the deformation and buckling of the cap mounting portion 8 are more reliably prevented, especially in the capping process, as compared with the method for manufacturing a bottle can corresponding to a cap having a diameter of 38 mm. can do. That is, in the capping step, when the hem winding portion at the lower end of the cap is wound around the valley portion 8a between the neck portion 7 and the bulging portion 8b of the cap mounting portion 8 by the hem winding roll of the capping device, the valley portion 8a is formed. The pressing force P inward in the radial direction and the amount of deformation (change in radius) ΔR of the valley portion 8a corresponding to this can be expressed by the following equation (1).

ΔR = R ² / (t × E) × P… (1)

In the above formula (1), P is the external pressure (pressure received by the valley portion 8a from the hem winding roll inward in the radial direction), R is the outer diameter (however, the radius) of the valley portion 8a, and t is the valley portion. In 8a, the thickness (thickness) of the can body 1 and E are the Young's modulus of the metal material of the can body 1. Therefore, from the above equation (1), it can be seen that when the external pressure P, the thickness t, and the Young's modulus E are constant, the deformation amount ΔR of the valley portion 8a is proportional to the square of the radius R of the valley portion 8a. Therefore, if the radius R of the valley portion 8a becomes smaller, the deformation amount ΔR of the valley portion 8a also becomes smaller in proportion to the square of the radius R (actually, when the radius R changes, the thickness t also becomes slightly smaller. Although it varies, it is not considered here because it is a minute amount.)

Therefore, the bottle of the present embodiment having the outer diameter D of the valley portion 8a corresponding to the cap having a diameter of 33 mm is about 30.7 mm, rather than the bottle can having the outer diameter of the valley portion corresponding to the cap having a diameter of 38 mm and having an outer diameter of about 35.4 mm. According to the above formula (1), the deformation amount ΔR of the valley portion 8a is reduced by about 25% when the pressing force received from the hem winding roll is the same as that of the can, and the deformation of the cap mounting portion 8 is ensured. Can be prevented. Therefore, even when the original plate thickness of the metal plate formed on the can body 1 is reduced as described above, the cap mounting portion 8 is affected by the forming load (axial load or lateral load) during capping. Deformation can be reliably prevented.

In the bottomed cylindrical body 11 of the present embodiment, the thickness t1 of the wall portion 13 is substantially constant as described above, but the thickness t1 is thicker on the flange portion 14 side of the wall portion 13. The wall portion 13 may be formed into a plurality of stages by forming a second-stage wall portion thinner than the thickness t2 of the flange portion 14. In such a case, the thickness t1 of the wall portion 13 may be the thickness of the thinnest portion on the bottom 2 side.

Next, an example of the present invention will be given to demonstrate the effect of the present invention. In this embodiment, the original plate thickness of the metal plate and the flange portion of the cylindrical portion 12 of the bottomed cylinder 11 are based on the first and second embodiments shown in FIGS. 1 to 3 and 4 to 6. Twenty-three types of bottomed cylinders 11 having various changes in the thickness t2 of 14 and the thickness t1 of the wall portion 13 and the step t2-t1 are formed by 1000 pieces in the DI press process, and the formability by the DI press machine (formability by DI press machine). DI formability) was confirmed, and 100 of these bottomed cylinders 11 were molded into the can body 1 in the bottleneck forming step, and the bottleneck formability (BN formability) at that time was confirmed. Furthermore, for 10 of these cans, the capping property was confirmed by measuring the resealing torque when actually capping a cap with a diameter of 33 mm in the capping process, opening the cap, and then screwing the cap back into the cap mounting part to reseal. bottom. These can bodies are molded in Table 1 as Examples 1 to 23 for those based on the first embodiment, and in Table 3 as Examples 31 to 52 for those based on the second embodiment. Shown with the mass of 1.

Further, as comparative examples with respect to Examples 1 to 23 and Examples 31 to 52, the original plate thickness, the thickness t2 of the flange portion 14, the thickness t1 of the wall portion 13, and the step t2-t1 were variously changed. For Examples 1 to 23 and Examples 31 to 52, 15 types of bottomed cylinders 11 were formed in the same manner by 1000 pieces in the DI pressing process to confirm DI formability, and these bottomed cylinders were formed. Of the bodies 11, 100 of the bodies 11 capable of forming a bottomed cylindrical body 11 having a predetermined height by DI press molding were molded into the can body 1 in the bottleneck molding step, and the BN formability at that time was confirmed. Further, the capping property was confirmed by measuring the resealing torque when 10 of them were capped in the capping step, then the cap was opened, and then the cap was screwed into the cap mounting portion again to reseal. These can be DI press-molded and bottleneck-molded in Table 2 as Comparative Examples 1 to 15 for Examples 1 to 23 and in Table 4 as Comparative Examples 31 to 45 for Examples 31 to 52. However, it is shown together with the mass of the molded can body 1.

In Examples 1 to 23 and Comparative Examples 1 to 15, the can height of the bottle cans was 132.6 mm on average within the range of the first embodiment, and the diameter of the body 5 was also the first. Within the range of the embodiment, it was 66.24 mm on average. Further, in Examples 31 to 52 and Comparative Examples 31 to 45, the can height of the bottle cans was 164.0 mm on average within the range of the second embodiment, and the diameter of the body portion 5 was also the second. It was 66.24 mm on average within the range of the embodiment. Further, in Examples 1 to 23 and Comparative Examples 1 to 15, and Examples 31 to 52 and Comparative Examples 31 to 45, the outer diameter (diameter) D of the valley portion 8a of the cap mounting portion 8 is 30 on average. The length of the portion of the bottomed cylindrical body 11 before being molded into the can body 1 of the bottle can, in which the thickness of the flange portion 14 is constant, is about 52 mm in the can axis C direction. rice field.

Here, the evaluation of DI formability is performed when all of the 1000 bottomed cylindrical bodies 11 to be molded can be DI press-molded without buckling, deformation, body breakage, punch removal failure, or the like. Is a circle mark, a triangle mark is used when the DI press machine is stopped once due to buckling, deformation, body breakage, etc. up to 1 out of 1000 pieces, and a cross mark is used when the DI press machine is stopped twice or more. And said.

In addition, the evaluation of BN formability was performed on 100 of the bottomed cylindrical bodies 11 that could be molded according to the predetermined dimensions in the DI press process, and in the bottleneck forming process, the shoulder portion 6, the neck portion 7, the valley portion 8a, and the swelling. When the cap mounting portion 8 including the protruding portion 8b, the screw portion 8c and the curl portion 8d is molded, and these are visually observed, all of them can be bottleneck molded according to the predetermined dimensions without causing buckling or the like. A circle mark was used, and a triangle mark was used when up to one buckling occurred, and a cross mark was used when two or more bucklings or deformations occurred.

Further, 10 can bodies 1 formed without buckling in the bottleneck forming process, and a bottomed tubular cap having a diameter of 33 mm having a top plate portion and a peripheral wall portion on the cap mounting portion 8 in the capping process. A capper manufactured by CSI Japan Co., Ltd. is used to cover the molded body and apply a vertical load (top pressure) in the direction of the can axis C of 850N to draw down the outer circumference of the top plate to form the step and roll set. With a diameter of 39.0 mm and a thread roller torque of 3.6 Nm, a load is applied to the top plate side of the peripheral wall portion on the radial inner peripheral side with respect to the can shaft C, and the female screw portion is formed so as to follow the screw portion 8c. It is also molded, and the roll set diameter is 39.0 mm, the skirt roller torque is 2.8 Nm, and the skirt roller is used to load the hem winding portion on the opposite side of the top plate portion of the peripheral wall portion to the inner peripheral side in the radial direction with respect to the can shaft C. Was given and the valley portion 8a at the lower end of the bulging portion 8b was wound (hem tightened). These capping conditions include capping conditions for a 310 ml aluminum alloy bottle can manufactured from an aluminum alloy plate having a current original plate thickness of about 0.345 mm, and the current original plate thickness of about 0. This is a review of the capping conditions for 410 ml aluminum alloy bottles manufactured from 400 mm aluminum alloy plates.

Here, the thread roller torque and the skirt roller torque are the magnitude of the load applied to the peripheral wall portion when the thread roller forms the female thread portion on the cap molded body, respectively, and the skirt roller determines the hem winding portion of the cap molded body. It is a substitute value of the magnitude of the load applied to the hem winding portion when winding around the valley portion 8a at the lower end of the bulging portion 8b, that is, the torque of the drive arm for pressing each roller on the radial inner peripheral side with respect to the can shaft C. Indicates a value. Further, the roll set diameter is the distance between the radial inner peripheral edges of the facing rollers when these rollers are at the initial set position farthest from the can shaft C (opposing with the can shaft C as the center). It is the diameter of the circle inscribed in the inner peripheral edge of the roller), and the tip load of each roller at the time of forming the female thread portion and at the time of winding the hem can be calculated from the roll set diameter, the thread roller torque and the skirt roller torque.

As for the capping property, the reseal torque when the cap molded from the cap molded body and attached to the cap mounting portion 8 is once opened in the capping step and then screwed into the cap mounting portion 8 again to reseal is measured. The case where the reseal torque is 20 N · cm or more is 0 cans is marked with a circle, the case where it is 1 can is marked with a triangle, and the case where it is 2 cans or more is marked with a cross. When the cap mounting portion 8 buckles or deforms due to the molding load in the capping process, the frictional resistance between the screw portion 8c of the can body 1 and the female screw portion of the cap increases, and the reseal torque also increases.

Of these, in Comparative Example 1 of Table 2 and Comparative Example 31 of Table 4, although the DI moldability, the BN moldability, and the capping property were all good, the original plate thickness was thick, so that Examples 1 to 23 and the examples were carried out. The mass was larger than that of Examples 31 to 52, and the weight was not sufficiently reduced. Further, in Comparative Examples 2 to 5 and Comparative Examples 32 to 35, the step t2-t1 was too large, so that a punch pull-out defect occurred, and the DI press machine was frequently stopped to perform stable DI press molding. could not. Further, in Comparative Examples 4 and 5 and Comparative Examples 6 to 10, and Comparative Examples 34 and 35 and Comparative Examples 36 to 40, the thickness t1 of the wall portion 13 was too thin, so that the wall portion 13 was formed in the bottleneck forming process. Many of them had buckling. Further, in Comparative Examples 11 to 15 and Comparative Examples 41 to 45, since the thickness t2 of the flange portion 14 was thin, many of the cap mounting portions 8 were buckled or deformed, and the reseal torque was increased to provide capping property. Was damaged.

In contrast to Comparative Examples 1 to 15 and Comparative Examples 31 to 45, in Examples 1 to 23 and Examples 31 to 52, buckling, deformation, and punch removal failure occur in all of the DI pressing steps. All 1000 bottomed cylinders 11 could be molded to a predetermined size without any need. Also, regarding the BN formability, buckling to 1 out of 100 in Examples 7, 11, 15, 19 and Examples 36, 40, 44, 48 in which the thickness t1 of the wall portion 13 was 0.100 mm. However, no buckling was confirmed other than these. Further, regarding the capping property, in Examples 20 to 23 and Examples 49 to 52 in which the thickness t2 of the flange portion 14 is 0.140 mm, only one can body 1 has a reseal torque of 20 N · cm or more. Other than these, no increase in reseal torque was observed.

Further, in Examples 1 to 23 which are bottle cans for 310 ml, the mass of the can body 1 is 16.0 g to 13.5 g compared to the conventional 17.5 g, and even in Examples 31 to 52 which are bottle cans for 410 ml. The weight of the can body 1 is 19.0 g to 16.5 g, which is 1.5 g or more, compared with the conventional 21.0 g, and it is possible to reduce the weight by 1.5 g or more. This means that each bottle can is insignificant, but considering that a huge number of bottle cans are distributed in the market, significant resource saving and energy saving can be achieved. The mass is an average value of the can body 1 that can be bottleneck molded.

1 Can body 2 Bottom 2a Dome 2b Circular convex 3 Outer circumference 4 Opening 5 Body 6 Shoulder 7 Neck 8 Cap mounting 8a Valley 8b Swelling 8c Thread 8d Curl 11 Bottomed cylinder 12 Cylindrical Part 13 Wall part 14 Flange part C Can shaft D Valley part 8a outer diameter (diameter)
H Can height t1 Thickness of wall portion 13 t2 Thickness of flange portion 14

Claims (2)

A cup-shaped material is formed from a metal plate having an original plate thickness of 0.250 mm to 0.300 mm and a 0.2% proof stress of 235 N / mm ² to 265 N / mm ² by drawing in a cupping press process.
This cup-shaped material is re-squeezed and ironed in the DI press process to have a bottom and a cylindrical portion, and the thickness of the wall portion, which is a thin-walled portion on the bottom side of the cylindrical portion, is 0.100 mm to 0. 130 mm, the thickness of the flange portion, which is a thick portion on the opposite side of the bottom of the cylindrical portion, is 0.140 mm to 0.200 mm, and the length of the portion where the thickness of the flange portion is constant in the can axis direction. A bottomed cylinder having a diameter of 42 mm to 60 mm and a step difference between the flange portion and the wall portion of 0.090 mm or less is formed.
In the bottleneck forming step on the flange portion of the bottomed cylinder, a shoulder portion whose diameter is reduced from the cylindrical body portion toward the side opposite to the bottom portion and a bulging portion bulging toward the outer peripheral side at the lower end are provided. By molding the cap mounting portion to have, the outer diameter of the valley portion, which is the minimum diameter portion between the bulging portion and the shoulder portion, is 28.7 mm to 32.7 mm, and the cap mounting portion is formed from the bottom portion. To manufacture a bottle can having a can body having a can height of 129.0 mm to 135.0 mm to the upper end, a body diameter of 64.24 mm to 68.24 mm , and a mass of 13.5 g to 16.0 g . A characteristic method for manufacturing bottle cans. A cup-shaped material is formed from a metal plate having an original plate thickness of 0.270 mm to 0.320 mm and a 0.2% proof stress of 235 N / mm ² to 265 N / mm ² by drawing in a cupping press process.
This cup-shaped material is re-squeezed and ironed in the DI press process to have a bottom and a cylindrical portion, and the thickness of the wall portion, which is a thin-walled portion on the bottom side of the cylindrical portion, is 0.100 mm to 0. 130 mm, the thickness of the flange portion, which is a thick portion on the opposite side of the bottom of the cylindrical portion, is 0.140 mm to 0.200 mm, and the length of the portion where the thickness of the flange portion is constant in the can axis direction. A bottomed cylinder having a diameter of 42 mm to 60 mm and a step difference between the flange portion and the wall portion of 0.090 mm or less is formed.
In the bottleneck forming step on the flange portion of the bottomed cylinder, a shoulder portion whose diameter is reduced from the cylindrical body portion toward the side opposite to the bottom portion and a bulging portion bulging toward the outer peripheral side at the lower end are provided. By molding the cap mounting portion to have, the outer diameter of the valley portion, which is the minimum diameter portion between the bulging portion and the shoulder portion, is 28.7 mm to 32.7 mm, and the cap mounting portion is formed from the bottom portion. To manufacture a bottle can having a can body having a can height of 160.0 mm to 166.5 mm to the upper end, a body diameter of 64.24 mm to 68.24 mm , and a mass of 16.5 g to 19.0 g . A characteristic method for manufacturing bottle cans.

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