JP2019111554A - Method for manufacturing bottle can - Google Patents

Abstract

To promote resource saving, energy saving and cost reduction in a can body.SOLUTION: A method for manufacturing a bottle can includes: DI pressing a cup-like base material formed of a metal plate having an original plate thickness of 0.330-0.375 mm; molding a bottomed cylindrical body having a bottom 2 and a cylindrical part whose a thickness of a wall part being a thin part of the cylindrical part is 0.115-0.130 mm, a thickness of a flange part being a thick part is 0.175-0.215 mm and a step between the flange part and the wall part is 0.100 mm or less; molding a cap fitting part 8 having a swelling part 8b on a shoulder part 6 and the lower end in the flange part of the bottomed cylindrical body; and manufacturing a bottom can having a can body 1 whose an outer diameter D of a trough part 8a being the minimum diameter part between the swelling part 8b and the shoulder part 6 is 28.7-32.7 mm, a can height H is 160.0-166.5 mm, and an outer diameter of the body part 5 formed of the cylindrical part is 64.24-68.24 mm.SELECTED DRAWING: Figure 1

Description

  In the present invention, the shoulder and the cap attachment are formed in the bottleneck forming step on the side opposite to the bottom of the cylindrical portion of the bottomed cylindrical body having the bottom and the cylindrical portion formed in the DI pressing step. The present invention relates to a method of manufacturing a bottle can having a can body.

  As a method of manufacturing such a bottle can, for example, Patent Document 1 describes a step of forming a can body made of metal (aluminum alloy), the can body has a bottom portion, and the bottom portion continues to the lower portion of the side wall. The side wall is squeezed and wall ironed to follow the wall, the wall continues to the open upper end, and the wall of the can body is formed thicker than the lower portion of the side wall Forming the frusto-conical portion and forming the frusto-conical portion by necking the wall several times to form the frusto-conical portion, wherein the frusto-conical portion is thicker than the can body wall and is Forming a frusto-conical section with a neck having a diameter smaller than the diameter of the can body, the neck following the cylindrical section near the upper opening, and forming a bead on the top of the metal can And onto the cylinder below the bead to secure the closure to the screw It describes a manufacturing method comprising the steps of forming, and forming an annular bead below the screws.

  Here, in this patent document 1, the typical drawn and ironed can body (DI can) used in the invention has a metal thickness of about 0.34 mm in the bottom cross section and about a thin portion in the thin part. It is stated that it may be 0.14 mm, and about 0.19 mm in thick part, such a can body is about 76.2 mm in diameter and about 187 mm for containing 591 ml in height, or It is also described that it may be about 216 mm to contain 887 ml.

  Further, in the patent document 1, another can body (DI can) for use in the invention has a metal thickness of about 0.25 to 0.38 mm in a bottom cross section and about 0.11 in a thin portion. To about 0.17 mm, and may be about 0.17 to 0.22 mm in thick sections, such cans having a diameter of about 63.5 to 88.9 mm and a height of about It is also described that it may be 127 to 254 mm.

JP, 2006-062755, A

  Here, although the bottle can manufactured by the manufacturing method described in this patent document 1 has a relatively large capacity as described above, it is an aluminum alloy for 410 ml generally distributed in Japan. The bottle can has a barrel with a diameter of about 66 mm and a height of about 164 mm, and has a bottomed cylindrical body (DI) having a bottom and a cylinder used for producing such a bottle can. Can) has a base plate thickness and a bottom thickness of about 0.400 mm, a thickness of a wall part which is a thin-walled bottom part of the cylindrical part is about 0.130 mm, and a thickness opposite to the bottom of the cylindrical part The thickness of the flange portion which is a thick portion is about 0.225 mm, and the mass is about 21.0 g.

  In addition, in the bottle can for drinks, such as coffee, in order to bring out the smell of the contents, the bulging part (annular bead) of the cap attaching part lower end corresponding to the cap whose diameter (approximate numerical diameter) is 38 mm Most of the valleys have an outer diameter (diameter) of about 35.4 mm between the neck and the valley, but the valley corresponds to a cap with a smaller outer diameter (diameter) of 33 mm in order to obtain ease of drinking. There are also bottle cans with an outer diameter of about 30.7 mm.

  By the way, in recent years, in such a bottle can, weight saving of the can main body is required for resource saving of the metal material which forms the can main body, and energy saving at the time of material manufacture, for example However, even with a large number of bottles that can be distributed in the market, it is possible to achieve significant resource saving, energy saving, reduction of carbon dioxide gas, or cost reduction of the can itself. Here, in order to reduce the weight of the can body as described above, it is conceivable to reduce the thickness of the base plate of the metal plate formed in the can body to thin the bottom portion, the wall portion, and the flange portion.

  However, simply reducing the thickness of the wall and flange by reducing the thickness of the base plate of the metal plate by mistake, the metal plate is redrawn in the DI press process to a cup-shaped material formed by drawing in the cupping press process. When ironing to form a bottomed cylindrical body, or at the flange portion of the bottomed cylindrical body thus formed, the shoulder (the above-described truncated conical portion), the neck, and the cap attachment portion When forming the above-mentioned bead, screw, and annular bead, there is a possibility that buckling or deformation may occur in the wall portion which has become thin.

  Further, as described above, in the DI pressing step, the wall portion which is a thin-walled portion is formed on the bottom portion side of the cylindrical portion of the bottomed cylindrical body, and the flange portion which is a thick-walled portion is formed on the opposite side to the bottom portion. The flange portion is formed on the outer surface of the punch that performs the above-described ironing process with a plurality of ironing dies in a DI press by forming a recess at a position corresponding to the flange portion of a bottomed cylindrical body from the wall portion It is too thick.

  However, if the difference in height between the flange and the wall increases due to thinning, the punchability of the punch from the bottomed cylinder is impaired and a dropout occurs, causing the DI press to stop and fail to drop. Because the body has to be removed from the punch, the production efficiency and yield of the bottle can may be significantly reduced. In addition, when the step is large, stress in the can axial direction due to a forming load may be concentrated on the step portion in the DI pressing step or the bottle neck forming step, which may also cause buckling or deformation.

  Furthermore, the upper end portion of the bottomed cylindrical body formed by the DI pressing step, or the upper end portion of the can main body in which the shoulder portion and the neck portion are formed in the bottleneck forming step in the bottomed cylindrical body In order to make the height and the can height of the can body uniform, trimming is performed to cut these upper end portions with a predetermined trim margin so as to be at a constant height from the bottom portion.

  However, in a metal plate whose original thickness is reduced, it is necessary to form a bottomed cylinder having a necessary height in order to form a bottomed cylinder in the DI pressing process without balancing the thickness of the flange portion and the thickness of the wall portion. Can not be formed, or even if it can be formed, in the can body formed in the bottle neck forming process from this bottomed cylindrical body, it becomes impossible to secure the necessary trim margin at the upper end, Due to shortage of production, the can body can not be treated as a defective product because the can body can not be at a certain height. Moreover, in order to eliminate such a lack of trim allowance, there is a limit also in enlarging the area of the said metal plate shape | molded by the bottomed cylindrical body, for example by DI press process.

  Furthermore, if the thickness of the flange portion becomes too thin, in the capping step of filling the can body with a beverage and the like and then attaching the cap, the capping is performed under the capping condition with the original original thickness of 0.400 mm, the cap It has been found that there is a possibility that the resealing torque may increase when the mounting portion is deformed or buckled, and the cap once removed is screwed again into the cap mounting portion to reseal.

  The present invention has been made under such a background, and the seat in the DI pressing process, the bottle neck forming process, and the capping process, even if the original plate thickness of the metal plate is reduced to reduce the weight of the can body. It is possible to form a bottomed cylindrical body or a can body without causing bending, punch failure, insufficient height of a bottomed cylindrical body, insufficient trimming cost of a can body, deformation or buckling of a cap attachment portion, etc. An object of the present invention is to provide a method of manufacturing a bottle can which 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 conducted intensive studies on a bottle can for 410 ml having an outer diameter (diameter) of about 30.7 mm corresponding to the cap of 33 mm in diameter described above. DI press process to a cup-shaped material formed by drawing from this metal plate in a cupping press process when the original thickness of the metal plate is reduced to about 0.330 mm to 0.375 mm in order to reduce the weight of the main body When redrawing and ironing are performed, the thickness of the wall portion which is the thin wall portion on the bottom side of the cylindrical portion is 0.115 mm to 0.130 mm, and the thick portion on the opposite side to the bottom portion of the cylindrical portion DI press work by forming a bottomed cylindrical body with a thickness of 0.175 mm to 0.215 mm for the flange portion and a step between the flange portion and the wall portion of 0.100 mm or less And can efficiently form the can body of a bottle can of a predetermined can height without causing buckling, punch missing, insufficient height, trim shortage, deformation of the cap attachment portion, etc. in a bottle neck forming process or capping process. It came to gain the knowledge that it could be formed into

  Then, based on such knowledge, the present invention solves the above-mentioned subject, and in order to achieve the above-mentioned purpose, as a manufacturing method of a bottle can for manufacturing a bottle can for 410 ml, original board thickness 0.330 mm- A cup-shaped material is formed by drawing from a 0.375 mm metal plate in a cupping press process, and the cup-like material is redrawn and ironed in a DI press process to have a bottom part and a cylindrical part, and the cylinder The thickness of the wall portion which is a thin portion at the bottom of the portion is 0.115 mm to 0.130 mm, and the thickness of a flange portion which is a thick portion opposite to the bottom portion of the cylindrical portion is 0.175 mm to 0.. A bottomed cylindrical body having a step difference of not more than 0.100 mm between the flange portion and the wall portion is formed by 215 mm, and the flange portion of the bottomed cylindrical body is subjected to a bottle neck forming step. By forming a shoulder portion which is reduced in diameter toward the side opposite to the bottom portion and a cap attachment portion having a bulging portion which is bulging outward at the lower end, the space between the bulging portion and the shoulder portion The outer diameter (diameter) of the valley portion which is the minimum diameter portion is 28.7 mm to 32.7 mm, and the can height from the bottom portion to the upper end of the cap mounting portion is 160.0 mm to 166.5 mm, It is characterized by manufacturing the bottle can which has a can main body whose outer diameter of the trunk | drum formed of the said cylindrical part is 64.24 mm-68.24 mm. The can height is preferably in the range of 162.0 mm to 166.5 mm.

  In the manufacturing method of the bottle can of such a configuration, the wall portion of the cylindrical portion and the thickness of the range based on the above-mentioned findings with respect to the metal plate whose thickness is reduced to 0.330 mm to 0.375 mm as the original plate thickness By forming the bottomed cylindrical body given to the flange portion in the DI pressing step, buckling or deformation in the DI pressing step and the subsequent bottle neck forming step or capping step, punch failure or insufficient height, A bottle can for 410 ml and having a can height of 160.0 mm to 166.5 mm, and an outer diameter of a body portion formed of the cylindrical portion is 64.24 mm to 68.24 mm without causing a shortage of trim allowance and the like. It is possible to manufacture a bottle can having a can body of

  That is, when the thickness of the wall portion is less than 0.115 mm, buckling may occur in the can body in the bottleneck forming step. In addition, if the thickness of the flange portion is less than 0.175 mm, there is a possibility that the cap attachment portion of the can body may be buckled or deformed when attaching the cap in the capping step after filling the beverage etc, resealing torque increases There is a fear. Furthermore, when the thickness of the wall portion exceeds 0.130 mm, or the thickness of the flange portion exceeds 0.215 mm, the bottomed cylinder or can formed from the metal plate having a thin original thickness as described above In the main body, there is a risk that the required height can not be obtained or that the trim allowance is insufficient.

  Furthermore, if the step between the flange portion and the wall portion exceeds 0.100 mm, punch failure may occur in the DI pressing process, or there may be a breakage, buckling, or the like. In addition, stress due to the forming load may be concentrated on the step portion in the bottleneck forming process, which may also cause buckling or deformation. The thickness of the wall portion is preferably in the range of 0.115 mm to 0.125 mm.

  Furthermore, the outer diameter (diameter) of the valley portion which is the minimum diameter portion between the bulging portion and the shoulder portion at the lower end of the cap attaching portion corresponding to the cap having a diameter of 33 mm is in the range of 28.7 mm to 32.7 mm In the method of manufacturing a bottle can according to the present invention, it is possible to more reliably prevent deformation or buckling of the cap attachment portion particularly in the capping step. Here, in the capping step, the radially inward pressing force P that the valley portion receives when winding the skirt winding portion (flare) of the lower end portion of the cap to the valley portion with the skirt winding roll of the capping device The amount of deformation (the amount of change in radius) ΔR of the valley portion can be expressed by the following equation (1).

ΔR = R ² / (t × E) × P (1)

  In the above equation (1), P is an external pressure (a pressure that the valley receives from the skirting roll toward the radially inward direction), R is an outer diameter of the valley (but radius), and t is a thickness of the valley E (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, thickness t and Young's modulus E are constant, the deformation ΔR of the valley is proportional to the square of the radius R of the valley. That is, if the radius R of the valley becomes smaller, the deformation amount ΔR of the valley also becomes smaller in proportion to the square of the radius R (In fact, when the radius R changes, the thickness t also slightly changes However, since it is a minute amount, it shall not be considered here.

  Therefore, the outer diameter of the valley corresponding to a cap of 33 mm in diameter (nominal diameter) is about 30.7 mm compared to a bottle can having a valley of about 35.4 mm in diameter corresponding to a cap of 38 mm in diameter (nominal diameter) Since the amount of deformation ΔR of the valley is reduced by about 25% according to the above equation (1) even if the pressing force received from the bottom roll is the same as in the prior art, the cap can be attached Deformation of parts is prevented. For this reason, according to the present invention, even in the case where the thickness of the base plate of the metal plate formed in the can body is reduced, the cap attachment portion is formed by the forming load (axial load and lateral load) at the time of capping. The deformation can be reliably prevented.

  As described above, according to the present invention, even if the thickness of the metal plate formed in the can body is reduced to reduce the weight of the bottle can, the DI pressing step, the bottle neck forming step, and the capping step are performed. Cans can be formed to a specified can height without causing buckling and deformation of bottomed cylindrical body and can body, insufficient height, insufficient trim allowance and punch defect, significantly saving resources It is possible to promote energy saving, reduction of carbon dioxide gas, and weight reduction of bottle cans.

It is a partially broken side view of the can main part of the bottle can manufactured in one embodiment of the present invention. It is a partially broken side view of the upper end part of the can main body shown in FIG. FIG. 2 is a partial schematic cross-sectional view of a bottomed cylindrical body formed in the can body shown in FIG.

  1 and 2 show a partially broken side view of a can body 1 of a bottle can for a volume of 410 ml manufactured in one embodiment of the present invention, and FIG. 3 shows a bottle in this one embodiment. It is a fragmentary sectional view which shows the outline of bottomed cylindrical body 11 shape | molded by the said can main body 1 in a neck formation process.

  As shown in FIG. 1, the can main body 1 of the bottle can manufactured according to the present embodiment is integrally formed with the bottom 2 and the bottom 2 from the outer peripheral edge of the bottom 2 to the upper end (upper side in FIG. 1) It has a substantially multistage bottomed cylindrical shape centering on the can axis C including the extending outer peripheral portion 3. In the bottom portion 2, a dome portion 2 a having a substantially arc-shaped cross section which is recessed inward in the can axis C direction (upper end side of the can body 1) is formed at the center, and an outer periphery of the dome portion 2 a is in the can axis C direction. The annular convex part 2b which protrudes outside (lower end side of the can main body 1) is continuously formed in the circumferential direction around the can axis | shaft C. As shown in FIG.

  Further, in the outer peripheral portion 3 sequentially from the bottom portion 2 toward the opening 4 on the upper end side of the can main body 1, the cylindrical body 5 centered on the can axis C and gradually inclined with a constant inclination toward the upper end side A frusto-conical shaped shoulder 6 with a reduced diameter, a tubular neck 7 extending from the shoulder 6 further toward the upper end, and an annular valley 8a recessed from the upper end of the neck 7 to the inner peripheral side of the can body 1 A bulging portion 8b protruding to the outer peripheral side with respect to the valley portion 8a, and a cap attaching portion 8 provided with a screw portion 8c and a curling portion 8d sequentially disposed on the upper end side of the bulging portion 8b are formed. ing.

  The can height H from the lower end edge (lower end edge of the annular convex portion 2b) of the bottom portion 2 of the can body 1 to the upper end edge (upper end edge of the curled portion 8d) of the outer peripheral portion 3 is a bottle can for 410 ml. In the case 1 of the can body, it is 160.0 mm-166.5 mm, preferably 162.0 mm-166.5 mm. Moreover, the outer diameter (diameter) of the trunk | drum 5 in the outer peripheral part 3 of the can main body 1 shall be 64.24 mm-68.24 mm.

In order to produce such a bottle can, first, in a cupping press process using a cupping press, a metal plate is punched into a disk shape and drawn to produce a cup-shaped material having a shallow depth. In the present embodiment, the metal plate formed into a cup-shaped material in this cupping press step is an aluminum plate having an original plate thickness of 0.330 mm to 0.375 mm or an aluminum alloy plate of A3004 or A3104 according to JIS H 4000. The 0.2% proof stress after baking at 205 ° C. for 20 minutes is in the range of 235 N / mm ^{2 to} 265 N / mm ² .

  Next, the cup-shaped material is redrawn and ironed in a DI press process using a DI press, and drawn in the direction of the can axis C, whereby the cylindrical portion 12 centered on the can axis C is formed on the outer peripheral portion. While forming the bottomed cylindrical body 11 as shown in FIG. 3 in which the dome portion 2a and the annular convex portion 2b similar to the can main body 1 are formed on the bottom portion 2. The thickness of the bottomed cylindrical body 11 and the bottom 2 of the can body 1 is substantially equal to the thickness of the base plate 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 that is substantially equal to the outer diameter of the body 5 of the can body 1. Further, a portion on the bottom portion 2 side of the cylindrical portion 12 is a wall portion 13 which is a thin wall portion whose thickness (thickness) is reduced, and on the upper end side (upper side in FIG. 2) opposite to the bottom portion 2 The portion is a flange portion 14 which is a thick portion which is thicker than the wall portion 13. Here, in order to form the wall portion 13 and the flange portion 14 having such different thicknesses in the cylindrical portion 12, as described above, in the punch for performing the ironing process with a plurality of ironing dies in the DI press machine. A recess having a depth in consideration of the thickness difference 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 between the wall portion 13 and the flange portion 14 gradually increases toward the upper end side of the bottomed cylindrical body 11. It is supposed to be. However, in FIG. 3, for the purpose of explanation, these thicknesses are drawn at a large ratio with respect to the height and the outer diameter of the bottomed cylindrical body 11. In the bottomed cylindrical body 11 of the present embodiment, the length in the can axis C direction of the portion where the thickness of the flange portion 14 is made constant is, for example, in the range of 42 mm to 60 mm.

  In the bottomed cylindrical body 11 shown in FIG. 3, the thickness t1 of the wall portion 13 which is a thin-walled portion of the cylindrical portion 12 is in the range of 0.115 mm to 0.130 mm. The thickness t2 of the flange portion 14 which is a thick portion is in the range of 0.175 mm to 0.215 mm. Furthermore, the step t2-t1 between the flange portion 14 and the wall portion 13 is set to 0.100 mm or less.

  The bottomed cylindrical body 11 thus formed is cleaned and dried in the first cleaning step after the upper end edge of the cylindrical portion 12 is cut at a predetermined trimming margin and the heights are aligned in the trimming step using a trimmer. Then, in the painting process, the inner and outer surfaces are painted and baked. Furthermore, in the bottomed cylindrical body 11 to which the painting has been applied, the diameter of the range of the flange portion 14 in the cylindrical portion 12 is reduced in the bottle neck forming step by the bottle necker, and the shoulder 6 and the neck 7 In the range of 28.7 mm to 32.7 mm in diameter D, the valley portion 8a of the cap attachment portion 8 to which the skirt winding portion (flare) of the 33 mm diameter can be wound is formed.

  Next, the upper end side of the valley portion 8a is expanded in diameter to form a bulging portion 8b, and after the screw portion 8c is formed on the upper end side of the bulging portion 8b, the upper end side is outer peripheral side than the screw portion 8c The cap attaching portion 8 is formed by being folded back and curled to form the curled portion 8d, and the can body 1 of the bottle can as shown in FIGS. 1 and 2 is formed. 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 screw portion 8c is in the range of 30.4 mm to 34.4 mm. Also in this bottleneck molding process, trimming may be performed as necessary.

  After the can body 1 thus formed is cleaned and dried in the second cleaning step, the presence of pinholes, foreign matter adhesion on the outer surface, scratches, stains, printing defects and the like are inspected in the inspection step and the can body is After being transported and filled with contents such as beverages, a cap (not shown) is attached, sealed, and shipped in a capping step. In addition, during the above-mentioned each forming process of the can main body 1 or during the forming process, bottom reforming may be performed in which the cross-sectional shape of the annular convex portion 2b of the bottom 2 is reshaped as needed.

  In the method for manufacturing a bottle can having such a configuration, the thickness t1 of the wall portion 13 in the cylindrical portion 12 is 0.115 mm to 0.130 mm in the bottomed cylindrical body 11 formed in the can body 1 in the bottle neck forming step. And the thickness t2 of the flange portion 14 is 0.175 mm to 0.215 mm, and the step t2-t1 between the flange portion 14 and the wall portion 13 is 0.100 mm or less. In the case of a bottle can for 410 ml without causing buckling or deformation of the bottomed cylindrical body 11 or the can main body 1, insufficient trim allowance and punch failure as described in the examples described below. The can body 1 of height H can be shape | molded.

  Therefore, even if the weight reduction of the bottle can is achieved by reducing the thickness of the base plate of the metal plate formed on the bottomed cylindrical body 11 as described above, the bottle can can be reliably and efficiently It can be manufactured. For this reason, in the current situation where a large number of bottle cans are distributed in the market, it is possible to achieve significant resource saving, energy saving, and reduction of carbon dioxide gas, and also to promote cost reduction of bottle cans. it can.

  Here, in the above-described bottomed cylindrical body 11, when the thickness t1 of the wall portion 13 is less than 0.115 mm, there is a possibility that the can body 1 may be buckled in the bottleneck forming step. In addition, when the thickness t2 of the flange portion 14 of the bottomed cylindrical body 11 is less than 0.175 mm, when the cap is attached in the capping step after the beverage or the like is filled, buckling, deformation, etc. There is a possibility that this may occur, and the resealing torque may be increased when re-sealing by screwing the cap once removed onto the cap mounting portion again. Even when the length in the can axis C direction of the portion where the thickness of the flange portion 14 is made constant is smaller than 42 mm, the shoulder portion 6 is formed in the capping step or in the capping step in the bottle neck forming step. May cause buckling or deformation.

  Furthermore, when the thickness t1 of the wall portion 13 exceeds 0.130 mm, or the thickness t2 of the flange portion 14 exceeds 0.215 mm, the necessary height of the above-mentioned thin original plate is obtained. Even if the bottomed cylindrical body 11 can not be formed, or even if it can be formed, such a bottomed cylindrical body 11 can not obtain the necessary height in the DI pressing process, resulting in a lack of trim allowance, resulting in a bottle Even if it is sent to the neck forming step, it becomes impossible to form the can body 1 of a predetermined can height H. In order to eliminate the insufficient height of the bottomed cylindrical body 11 and the insufficient trim allowance of the can body 1, it is also conceivable to increase the area by punching out the above-mentioned metal plate in the shape of a disc and increase the area. In the case of a metal plate of the specified width, there is a limit to increase the diameter in consideration of productivity, and the thickness t1 of the wall portion 13 in the bottomed cylindrical body 11 formed from a disc punched from such a metal plate However, if the thickness t2 of the flange portion 14 exceeds 0.215 mm or if the thickness t2 of the flange portion 14 exceeds 0.215 mm, sufficient weight reduction of the can body 1 can not be achieved even if there is no shortage of trim allowance There is also a fear.

  Furthermore, if the step difference t2-t1 between the flange portion 14 and the wall portion 13 exceeds 0.100 mm, punch failure may occur in the DI pressing process, and the DI press may be stopped to fail. Since the cylindrical body 11 must be removed from the punch, the manufacturing efficiency and the yield of the bottle can decrease. Furthermore, if the step t2-t1 is too large, stress due to the forming load may be concentrated on the step portion in the DI pressing step or the bottle neck forming step, and the bottomed cylindrical body 11 or the can body 1 may be buckled or deformed. 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 attaching portion 8 corresponding to the cap having a diameter of 33 mm and the shoulder 6 is 28.7 mm to 32.32. In the manufacturing method of the bottle can of the present embodiment, which is in the range of 7 mm, deformation and buckling of the cap attachment portion 8 are more surely prevented particularly in the capping step as compared to the manufacturing method of the bottle can corresponding to the 38 mm diameter cap can do. That is, in the capping step, the valley portion 8a is formed when winding the hem winding portion at the lower end of the cap to the valley portion 8a between the neck portion 7 and the bulging portion 8b of the cap attaching portion 8 by the hem winding roll of the capping device. The pressing force P directed radially inward and the amount of deformation (the amount of change of the radius) ΔR of the valley portion 8a according to this can be expressed by the following formula (1).

ΔR = R ² / (t × E) × P (1)

  In the above equation (1), P is an external pressure (a pressure that the valley 8a receives from the bottom roll toward the radially inward direction), R is an outer diameter (where a radius) of the valley 8a, and t is a valley The thickness (thickness) of the can body 1 at 8 a, E is the Young's modulus of the metal material of the can body 1. Therefore, it can be understood from the above equation (1) that when the external pressure P, thickness t and 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 (In fact, when the radius R changes, the thickness t also becomes slightly Although it changes, it is not considered here because it is a minute amount.

  Therefore, the bottle according to this embodiment has an outer diameter D of about 30.7 mm corresponding to a cap of 33 mm in diameter rather than a bottle can having an outer diameter of about 35.4 mm corresponding to a cap of 38 mm in diameter According to the above equation (1), the amount of deformation ΔR of the valley portion 8a is reduced by about 25% according to the above equation (1) and the deformation of the cap mounting portion 8 can be reliably made Can be prevented. For this reason, even in the case where the thickness of the base plate of the metal plate formed in the can body 1 is reduced as described above, the cap attachment portion 8 is formed by the forming load (axial load and lateral load) at the time of capping. The 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 on the flange portion 14 side of the wall portion 13 is greater than the thickness t1, The wall portion 13 may be formed in a plurality of steps, for example, by forming a second-stage wall portion thinner than the thickness t2 of the flange portion 14 or the like. In such a case, the thickness t1 of the wall portion 13 may be the thickness of the thinnest portion which is the thinnest on the bottom 2 side.

  Next, the effects of the present invention will be demonstrated using examples of the present invention. In the present embodiment, first, based on the embodiment shown in FIGS. 1 to 3, the base plate thickness of the metal plate, the thickness t2 of the flange portion 14 of the cylindrical portion 12, the thickness t1 of the wall portion 13 and the step t2- Twelve kinds of bottomed cylindrical bodies 11 in which t1 is changed variously are formed by 1000 pieces in a DI pressing process to confirm the formability (DI formability) by a DI press, and 100 pieces of each have a bottomed side The cylindrical body 11 is formed into the can body 1 in the bottle neck forming step, and the bottle neck formability (BN formability) at that time is confirmed, and 10 of the cans are capped in the capping step and then opened. After that, the sealing property (capping property) was confirmed by measuring the resealing torque at the time of resealing by screwing the cap into the cap mounting portion again. These are shown in Table 1 together with the mass of the molded can body 1 as Examples 1 to 12.

  Moreover, as a comparative example with respect to these Examples 1 to 12, ten types of bottomed cylindrical bodies in which the thickness t2 of the base plate thickness, the flange portion 14, the thickness t1 of the wall portion 13 and the step t2-t1 are variously changed. Similarly, while confirming the DI formability by molding 1000 pieces of each 11 in the DI pressing step, it is possible to form the bottomed cylindrical body 11 of a predetermined height by DI press forming among these bottomed cylindrical bodies 11 100 pieces are formed into the can body 1 in the bottle neck forming step, the BN formability at that time is confirmed, and 10 pieces of them are capped in the capping step and then opened and then the cap is attached again The sealing property (capping property) was confirmed by measuring the resealing torque at the time of screwing in and resealing. These are shown in Table 2 together with the mass of the molded can body 1 as Comparative Examples 1 to 10.

  In Examples 1 to 12 and Comparative Examples 1 to 10, the can height H was 164.0 mm on average, and the diameter of the body 5 was 66.24 mm on average. Furthermore, in these Examples 1 to 12 and Comparative Examples 1 to 10, the outer diameter (diameter) D of the valley portion 8a of the cap attachment portion 8 was 30.7 mm on average. Further, in the bottomed cylindrical body 11 before being formed into the can main body 1 of the bottle can in these Examples 1 to 12 and Comparative Examples 1 to 10, the can axis of the portion where the thickness of the flange portion 14 is made constant. The length in the C direction was about 52 mm.

  Here, the DI formability is evaluated when all of the 1000 bottomed cylindrical bodies 11 to be molded can be subjected to DI press forming without causing buckling, deformation, breakage of the cylinder, punch failure or the like. Is marked with a circle, and buckling, deformation, torso and the like occur up to one in 1000 pieces, and the DI press machine stops once as a triangle mark, and the DI press machine crosses twice or more when it stops And

  In addition, evaluation of BN formability was carried out on 100 of the bottomed cylindrical bodies 11 that could be molded to predetermined dimensions in the DI pressing step, shoulders 6, necks 7 and valleys 8a in the bottleneck forming step. The cap mounting portion 8 including the projecting portion 8b, the screw portion 8c and the curling portion 8d is molded, and these are visually observed, and all can be formed into a bottle neck according to a predetermined size without causing buckling or the like. Circles were marked, and one with a buckling or the like was marked with a triangle, and two or more with a buckling or deformation with a cross.

  Furthermore, a bottomed cylindrical cap having a diameter of 33 mm and having a top plate portion and a peripheral wall portion at the cap attachment portion 8 in the capping process in 10 can main bodies 1 formed without causing buckling etc. in the bottleneck forming process. The top of the top plate portion is drawn by applying a vertical load (top pressure) in the can axis C direction of 1000 N with a capper manufactured by CSI Japan Co., Ltd. with a molded body covered, and the step portion is formed. A thread is applied to the top plate side of the peripheral wall by a thread roller with a diameter of 39.0 mm and a thread roller torque of 3.8 N · m to apply a load to the inner peripheral side in the radial direction with respect to the can axis C to follow the screw 8c. Similarly, with the top plate of the peripheral wall by the skirt roller with a roll set diameter of 39.0 mm and a skirt roller torque of 3.0 N · m And wound up to give a load to the hem wound portion of the contralateral radially inner side with respect Kanjiku C in the valley portion 8a of the bulging portion 8b bottom (hem tightening).

  Here, the thread roller torque and the skirt roller torque respectively indicate the magnitude of the load given to the peripheral wall portion when the thread roller forms the female screw portion in the cap molded body, and the skirt roller is the hem winding portion of the cap molded body It is a substitute value of the size of the load given to the hem winding portion when winding and tightening 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 radially inward with respect to the can axis C Indicates the value. Further, with the roll set diameter, the distance between the edge portions on the radially inner peripheral side of the opposing rollers (when the rollers are at the initial set position farthest from the can axis C (the center of the can axis C is opposed) The diameter of a circle inscribed in the inner peripheral edge of the roller), and the tip load of each roller at the time of forming an internal thread portion and at the time of skirting can be calculated from this roll set diameter, thread roller torque and skirt roller torque.

  With regard to the sealing property (capping property), the cap formed in the capping step in the capping step and once attached to the cap attachment portion 8 is once opened and then screwed again to the cap attachment portion 8 for resealing. The resealing torque was measured, and the case where the resealing torque was 20 N · cm or more was 0 can is indicated by a circle, the case with 1 can was indicated by a triangle, and the case with two can or more was indicated by a cross. . When the cap mounting portion 8 is buckled or deformed by the forming load in the capping step, the frictional resistance between the screw portion 8c of the can body 1 and the female screw portion of the cap increases, and the resealing torque also increases.

  Among them, first, in Comparative Example 1 of Comparative Examples 1 to 10 in Table 2, thickness t2 of flange portion 14 is large, thickness t1 of wall portion 13 is small, and step t2-t1 is large, and even in Comparative Example 2 Since the thickness t1 of the wall portion 13 is thin and the step t2-t1 is large, punch failure occurs in the DI pressing process, and the DI press is frequently stopped and stable DI press molding can not be performed. The Furthermore, since the thickness t1 of the wall portion 13 was thin also in the comparative example 2 and the comparative examples 3 to 5 and 10, many cases in which the wall portion 13 was buckled in the bottleneck forming step.

  Further, in Comparative Examples 6 to 10, although the sealing property (capping property) was evaluated, in Comparative Examples 1 and 3, since the thickness t2 of the flange portion 14 was thin, in the capping step The buckling and deformation occurred, and the capping property was impaired. Among them, in Comparative Examples 9 and 10, the thickness t2 of the flange portion 14 can not be sufficiently secured even if the thickness t1 of the wall portion 13 is thin because the base plate thickness is too thin.

  With respect to such Comparative Examples 1 to 10, in Examples 1 to 12, all 1000 bottomed cylindrical bodies in the DI pressing step without causing buckling, deformation, punch omission failure, and lack of trim allowance. 11 was able to be formed into a predetermined size. Furthermore, with regard to the BN formability, in the examples 3, 6, 9 and 12 in which the thickness t 1 of the wall portion 13 was 0.115 mm, which is the lower limit value of the range of the embodiment, buckling was made to one in 100. Although it was recognized, no one other than these confirmed buckling. Further, with respect to the sealing property (capping property), there was no can body 1 having a reseal torque of 20 N · cm or more, and no increase in reseal torque was observed.

  And in Examples 1 to 12 which are bottle cans for 410 ml, the mass of the can main body 1 is 19.2 g to 17.1 g, and each is about 1.5 g or more with respect to the conventional 21.0 g. It was possible to reduce the weight. This means that although one bottle can is insignificant, significant resource saving and energy saving can be achieved in consideration of distribution of a large number of bottle cans in the market. In addition, mass is an average value of the can main body 1 which could be bottleneck-molded.

DESCRIPTION OF SYMBOLS 1 can main body 2 bottom part 2a dome part 2b annular convex part 3 outer peripheral part 4 opening part 5 body part 6 shoulder part 7 neck part 8 cap attachment part 8a valley part 8b bulging part 8c screw part 8d curled part 11 bottomed cylindrical body 12 cylinder Part 13 Wall part 14 Flange part C Can axis D Outer diameter (diameter) of valley part 8a
H Can height t1 Thickness of wall portion 13 Thickness of flange portion 14

Claims (1)

A cup-shaped material is formed by drawing from a metal plate having a original thickness of 0.330 mm to 0.375 mm in a cupping press process,
This cup-shaped material is subjected to redrawing and ironing in a DI pressing process, and has a bottom and a cylindrical portion, and the thickness of the wall portion which is a thin portion on the bottom of the cylindrical portion is 0.115 mm to 0.. A bottomed cylindrical body having a thickness of 0.175 mm to 0.215 mm, and a step between the flange portion and the wall portion having a thickness of 0.100 mm or less, which is 130 mm thick at the thick portion opposite to the bottom of the cylindrical portion Molding
The flange portion of the bottomed cylindrical body has a shoulder portion which is reduced in diameter toward the side opposite to the bottom portion in a bottle neck forming step, and a cap attachment portion having a bulging portion which is bulging outward at the lower end. By forming, 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 from the bottom portion to the upper end of the cap mounting portion A bottle can having a can body having a can height of 160.0 mm to 166.5 mm and an outer diameter of a body portion formed by the cylindrical portion of 64.24 mm to 68.24 mm. How to make bottle cans.

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