JP2019063813A - Can manufacturing method and can manufacturing device - Google Patents

Abstract

To provide a can manufacturing method and a can manufacturing device capable of enhancing the strength of a can in its axial direction.SOLUTION: A can manufacturing method comprises: a cylindrical can forming process of forming a cylindrical can which has, in a bottom part, an annular projection part extending in the circumferential direction around a can axis and a taper surface part extending from the outer peripheral edge of the annular projection part by applying restriction squeezing processing to a metal plate and which has an upper end of the taper surface part connected to a trunk part via a bending part; and a bottom part remolding process of remolding a part from a taper part to a lower end part of the trunk part. The bottom part remolding process remolds a part from the taper part to the lower end part of the trunk part as a curved surface projecting outward with a radius of curvature larger than that of the bending part.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method of manufacturing a can filled with a beverage and the like, and a manufacturing apparatus of the can.

DESCRIPTION OF RELATED ART Conventionally, the bottle can which diameter-reduced the opening end part of the can which integrated the can bottom and formed in the bottle shape is known (for example, refer patent document 1). The bottle can described in Patent Document 1 can be manufactured through a cup forming process, a drawing and ironing process (DI process), a trimming process, a print coating process, a necking process, and a neck forming process in this order.
Specifically, a metal plate is punched into a disk shape and drawn by a cupping press to form a cup-like body, and the cup-like body is drawn and ironed to draw a peripheral wall, and a bottomed cylindrical can Form a body. At this time, a dome portion recessed toward the inside of the can is formed at the bottom of the bottomed cylindrical can, and an annular convex portion is formed at the peripheral portion of the dome, and from the outer peripheral edge of the annular convex portion A tapered portion gradually expanding in diameter is formed toward the lower end of the body portion.

  Then, the open end of the squeezed and processed can body is trimmed to make the height of the peripheral wall uniform over the entire circumference. After the trimming process, printing and coating are performed on the outer surface of the body of the can, and then a neck portion which is reduced in diameter toward the opening end and a mouth portion in which a screw portion such as a cap is screwed are formed. Will be produced.

JP, 2016-30279, A

  By the way, although the thickness reduction of material is calculated | required in this kind of can, it is desired to raise the intensity | strength of the axial direction of a can so that a buckling etc. may not arise with this thickness reduction.

  This invention is made in view of such a situation, and an object of this invention is to raise the intensity | strength of the axial direction of a can.

  The manufacturing method of the can of the present invention includes drawing an annular convex portion along the circumferential direction around the can axis at the bottom by applying a drawing and ironing process to a metal plate, and an outer peripheral edge of the annular convex portion. Forming a cylindrical can having a tapered surface portion extending from the upper surface of the tapered surface portion and the upper end of the tapered surface portion connected to the body portion via the bending portion; and from the tapered portion to the lower end portion of the body portion And a bottom re-forming step of re-forming the deformed portion, wherein the bottom re-forming step outwards a portion of the tapered portion applied to the lower end of the body with a curvature radius larger than the curvature radius of the bent portion. Reshape into a convex curved surface.

Since the portion from the outer peripheral edge of the annular convex portion formed by the cylindrical can forming step to the lower end of the body is reshaped into a curved surface with a larger radius of curvature in the bottom portion reforming step, the axial strength (column strength ) Can be raised.

In a preferred embodiment of the method for producing a can according to the present invention, a diameter reducing portion forming step of forming a diameter reducing portion in which a portion on the open end side of the cylindrical can is reduced after the bottom portion reforming step Good.
Since the strength (column strength) of the cylindrical can in the axial direction is increased by the bottom portion re-forming step, when the reduced diameter portion is formed by the reduced diameter portion forming step, the cylindrical can is in the axial direction from the open end side. Even when pressed in the direction, the pressing force along the axial direction of the cylindrical can can be received on the entire curved surface, and concentration of the pressing force on the lower end portion of the body can be suppressed. Therefore, the lower end of the body can be made less likely to be distended.

In a preferred embodiment of the method for producing a can according to the present invention, a printing step of printing around the body portion may be provided between the cylindrical can formation step and the bottom portion re-forming step.
Here, when the lower end portion of the body portion and the tapered portion are re-shaped into a curved surface, it is difficult to print on the curved surface. On the other hand, in the above aspect, since printing is applied before the bottom reforming step, the printing area in the axial direction in the body is made larger than when the printing step is performed after the bottom reforming step. it can. That is, it becomes possible to print also to the trunk section reshaped to a curved surface by the bottom section remolding process.

  The apparatus for manufacturing a can of the present invention has, at the bottom, an annular convex along the circumferential direction around the can axis, and an annular convex that is downwardly convex, and a tapered surface extending from the outer peripheral edge of the annular convex, the taper An internal mold having a convex curved surface which is inserted into a cylindrical can whose upper end is connected to the body via a bend and which supports from the inside the portion extending from the tapered surface to the lower end of the body from the inside; And an outer mold having a concave surface for pressing from the outside a portion of the cylindrical can supported from the inner side by the inner mold from the tapered portion of the cylindrical can to the lower end of the body, the inner mold The convex curved surface and the concave curved surface of the outer mold are formed to have a radius of curvature larger than the radius of curvature of the bent portion.

The can manufacturing apparatus of the present invention can reshape a cylindrical can with a simple configuration in which the inner and outer molds sandwich and press the cylindrical can.

  According to the present invention, the axial strength of the can can be increased.

It is a front view showing the container which attached the cap to the bottle can manufactured by the manufacturing method of the embodiment of the present invention, and is the figure which made the right half which passes a can axis a section. It is the front view which made the right half a section showing the process until it forms a cup and forms a cylindrical can among the manufacturing processes of a bottle can. It is a side view of a bottle can manufacturing device. It is sectional drawing in alignment with the AA of FIG. It is a front view which shows the bottom part re-forming apparatus used for the bottom part re-forming process among the manufacturing processes of a bottle can. It is the front view which made the right half the section showing the process of re-forming the bottom of a cylindrical can among the manufacturing processes of a bottle can. It is sectional drawing which shows the printing area | region of the trunk | drum in before bottom part shaping | molding. It is sectional drawing which shows the printing area after bottom part shaping | molding. It is the front view which made the right half the section showing the process until forming a shoulder and a diameter reduction part in the field by the side of the opening end of a cylindrical can among manufacturing processes of a bottle can. It is the front view which made the right half the section showing the process until forming an enlarged diameter part in a diameter-reduced part of a cylindrical can among bottle can manufacturing processes. It is the front view which made the right half the section showing the process until forming a curl part in the opening end of a cylindrical can among bottle can manufacturing processes.

Hereinafter, embodiments of the present invention will be described.
The container 1 consists of a bottle can 10 and a cap 30 attached to the open end thereof, as shown in FIG. In the following description, the vertical direction is determined by the direction shown in FIG.
As shown in FIG. 1, the bottle can 10 is made of thin sheet metal of aluminum or aluminum alloy, and radially inward at a cylindrical body 12 extending from the periphery of the bottom 11 and the bottom 11 and the upper end of the body 12 A shoulder 13 reduced in diameter to be bent, a reduced diameter portion 14 whose diameter is gradually reduced from the shoulder 13 upward in the can axial direction, and an enlarged diameter once enlarged at the upper end of the reduced diameter portion 14 It has a portion 15 and a curled portion 16 formed above the enlarged diameter portion 15. In the bottle can 10, the open end having the curled portion 16 is referred to as a mouth 17.

The bottom portion 11 is an annular shape along the circumferential direction around the can axis from the peripheral portion of the can bottom recess portion 111 recessed toward the inner side (opening end portion side) of the bottle can 10 and is downwardly convex. The annular convex portion 112 is formed, and the curved portion 113 which is convex outward while gradually increasing the diameter from the outer peripheral edge of the annular convex portion 112 to the trunk portion 12. When the bottle can 10 is placed on a desk or the like, the tip of the annular convex portion 112 is grounded. Although the can bottom concave portion 111 is formed in a dome shape, it may be formed in a flat surface orthogonal to the can axis from the inner peripheral edge of the annular convex portion 112.
Further, the curved portion 113 is formed by re-forming the bottom portion 411 of the cylindrical can 41 formed as shown in FIG. 2B in the cylindrical can-forming step described later in the re-forming step. .

Such a bottle can 10 is manufactured by performing a cylindrical can formation process, a printing coating process, a bottom part remolding process, a diameter reduction part formation process, a diameter expansion part formation process, and a curl formation process in this order. The manufacture of the bottle can 10 is performed by a bottle can manufacturing apparatus. Details will be described below.
[Cylinder can formation process]
In order to manufacture such a bottle can 10, first, an aluminum plate material is punched out and drawn to form a shallow cup 40 having a relatively large diameter as shown in FIG. Then, drawing and ironing (DI processing) are performed again to form a cylindrical can 41 having a predetermined height as shown in FIG. 2 (b), and its upper end is trimmed by trimming. In this cylindrical can forming step, as shown by a two-dot chain line in FIG. 2B, a punch sleeve 21 for pressing a metal plate and a punch sleeve 21 disposed opposite to the punch sleeve 21 sandwich the metal plate together with the punch sleeve 21. It is performed by the cylindrical can formation apparatus provided with the die | dye 23 which irons a metal plate between the dome formation part 22 and the punch sleeve 21. As shown in FIG. The cup 40 is squeezed and ironed by the cylindrical can forming device to form the cylindrical can 41.
The bottom portion 411 of the cylindrical can 41 has a can bottom concave portion 111, an annular convex portion 112 continuous with the outer peripheral edge of the can bottom concave portion 111, and a taper gradually expanding in diameter from the outer peripheral edge of the annular convex portion 112 to the lower end of the trunk portion 413. As shown in FIG. 7, the curvature radius R1 of the cylindrical can 41 is convex at the boundary between the tapered portion 412 and the body portion 413. The radius of curvature at the outer surface) is formed with a bend portion 414. Further, the tapered portion 412 is formed in a substantially straight shape in the vertical cross section.

[Printing process]
The printing coating process is performed by the printing coating apparatus which comprises a bottle can manufacturing apparatus, and forms the coating film which laminated | stacked the base layer, the printing layer, and the overcoat layer in this order on the surface of the cylindrical can 41. Specifically, after the paint that constitutes the base layer is applied to the surface of the cylindrical can 41, the base layer is formed by being transported to an oven and dried. Then, the ink is printed on the base layer to form a print layer. In this case, the upper end portion of the cylindrical can 41 is printed up to the area where the diameter-reduced portion 14 is to be formed, and the lower end portion of the cylindrical can 41 is, as shown in FIG. The image is printed in the area P up to
Then, an outer surface paint constituting an overcoat layer is applied onto the print layer. The outer surface coating is applied to substantially the entire surface of the cylindrical can 41 to cover and form the printing layer and the base layer. After the application of the outer surface paint, the cylindrical can 41 is heated and baked in an oven furnace.
The inner surface paint is sprayed also on the inner surface of the cylindrical can 41 after the printing process of the outer surface, and the inner surface paint is baked on the inner surface of the cylindrical can 41 by heating in an oven.

[Configuration of bottle shape forming apparatus]
Next, the bottle can 10 is formed by the bottle shape forming apparatus 50 shown in FIGS. 3 and 4. The bottle shape forming apparatus 50 includes a bottom remolding apparatus for remolding the bottom 411 of the cylindrical can 41, a reduced diameter portion forming apparatus for forming the reduced diameter section 14 of the bottle can 10, and an enlarged upper end of the reduced diameter section 14. It functions as an enlarged diameter portion forming device that forms the diameter portion 15 and a curled portion formation device that forms the curled portion 16 above the enlarged diameter portion 15.
Next, the bottle shape forming apparatus 50 will be described. In addition, this bottle shape forming apparatus 50 is for processing the cylindrical can 41 formed as mentioned above into the bottle can 10 of final shape, and the shape of the can changes according to the progress of processing. However, in the following, when the shape of the can is not particularly limited from the cylindrical can 41 to the bottle can 10, the intermediate formed body 43 will be described.

  The bottle shape forming apparatus 50 has a work holding portion 51 which holds the plurality of intermediate formed bodies 43 by arranging the can axis direction horizontally and holds them, and a plurality of forming tools 52 which apply various forming processes to the intermediate formed bodies 43. And a driving unit 54 for driving both the holding units 51 and 53. The workpiece holding side of the workpiece holding portion 51 holding the intermediate formed body 43 and the tool holding side of the tool holding portion 53 holding the forming tool 52 are disposed to face each other.

  The work holding portion 51 has a configuration in which a plurality of holding devices 57 for holding the intermediate formed body 43 are annularly arranged along the circumferential direction on the surface of the disk 56 supported by the support shaft 55 facing the tool holding portion 53. It is done. The bottom of the intermediate formed body 43 supplied from the supply unit 58 via the supply side star wheel 59 is intermittently transmitted to the holding device 57 by the disk 56 being intermittently rotated by the drive unit 54 about the support shaft 55. They are held one by one and conveyed in the circumferential direction of the disk 56. The intermediate formed body 43 is formed by the forming tools 52 of the tool holding portion 53 during conveyance by the disk 56, and then sequentially discharged to the discharge portion 61 as the bottle can 10 after forming via the discharge side star wheel 60. .

  The tool holding portion 53 has a plurality of various forming tools 52 arranged in a ring along the circumferential direction on the surface of the disk 63 supported by the support shaft 62 facing the workpiece holding portion 51, and the disk 63 is supported by the drive portion 54 It is configured to advance and retract in the axial direction of the shaft 62. The support shaft 62 is coaxially provided inside the support shaft 55.

  The tool holding portion 53 includes a punch sleeve for re-forming the bottom of the cylindrical can 41 and a plurality of necking molds for reducing the diameter (neck-in processing) of the opening of the intermediate molded body 43, and a curl portion 16 A plurality of forming tools 52 for performing processing according to each processing step, such as a curled part forming tool for forming a frame, are provided. The forming tools 52 are annularly arranged in the circumferential direction on the disk 63 in the order of steps.

  The intermittent rotation stop position of the work holding portion 51 (disk 56) whose center of rotation is the axis line of the support shaft 55, the can axis of each intermediate formed body 43 whose opening portion is directed to the tool holding portion 53 side It is set to coincide with the central axis of 52 respectively. Then, by the intermittent rotation of the disk 56 by the drive unit 54, each intermediate formed body 43 is rotationally moved to a position opposed to each forming tool 52 for the next process, and the processing of the next stage is performed.

  That is, when the tool holding portion 53 advances and the work holding portion 51 and the tool holding portion 53 approach each other, each forming tool 52 performs processing according to each process on the intermediate formed body 43, and both holding portions 51 , 53 are moved away from each other so that the forming tool 52 in the next step faces the respective intermediate formed body 43. As described above, by repeating the operations that the two holding portions 51 and 53 approach, process, separate and rotate the intermediate molded body 43, the bottom 11, the body 12, the shoulder 13, and the reduced diameter portion 14 of the intermediate molded body 43 are repeated. The enlarged diameter portion 15 and the curled portion 16 are sequentially formed to form the bottle can 10.

Next, a method of forming the cylindrical can 41 that has undergone the cylindrical can forming step and the printing step into the bottle can 10 by the bottle shape forming apparatus 50 will be described in order of steps.
[Bottom re-forming process]
In the bottom portion re-forming step, a portion of the bottom portion 411 of the bottom portion 411 of the cylindrical can 41 subjected to print coating in the print coating step from the tapered portion 412 to the lower end portion of the body portion 413 is reshaped into a curved surface convex outward The curved portion 113 of the bottle can 10 is formed.
This bottom portion re-forming step is performed by a bottom portion re-forming apparatus comprising an inner punch 70 and a base die 80, as shown in FIGS. The inner punch 70 is a part of the forming tool 52 in the bottle shape forming apparatus 50, and the base die 80 is a part of the holding device 57 in the bottle shape forming apparatus 50. Details will be described below.

The inner punch 70 is inserted into the inside of the cylindrical can 41 and is connected to the inner mold 71 supporting the bottom 411 and the body 413 of the cylindrical can 41 from the inside, and is connected to the inner mold 71. And a support shaft 72 for moving the mold 71 in the vertical direction. The inner mold 71 includes an annular convex portion 73, a convex curved surface portion 74 whose diameter gradually increases upward from the outer peripheral edge of the convex portion 73, and a cylindrical portion 75 extending upward from the edge of the convex curved surface portion 74. And have. Among them, the convex curved surface portion 74 is disposed to be opposed to a portion extending from the tapered portion 412 to the lower end portion of the body portion 413 when the cylindrical can 41 is held between the inner mold 71 and the base die 80. The curved surface is a convex surface with a radius of curvature larger than the radius of curvature R1 of the bent portion 414 located at the boundary between the tapered portion 412 and the body portion 413 of the cylindrical can 41. That is, the surface of the convex curved surface portion 74 is a support surface that supports the inner surface of a portion of the tapered portion 412 of the cylindrical can 41 and the lower end portion of the trunk portion 413.
Further, as shown in FIGS. 5 and 6, when the cylindrical can 41 is held between the inner mold 71 and the base die 80 at substantially the center of the convex portion 73, the can bottom concave portion 111 of the cylindrical can 41 is A recess 76 capable of receiving a portion is formed.

The base die 80 corresponds to the outer mold of the present invention, and is a member that presses the bottom 411 of the cylindrical can 41 from the outside, and is disposed to face the inner mold 71. The upper surface portion 81 of the base die 80 is formed with a recess 82 into which the tip portion of the inner mold 71 is fitted. The concave portion 82 is formed of a bottom surface portion 83 and a concave surface portion 84 whose diameter gradually increases upward from the outer peripheral edge of the bottom surface portion 83. Among them, the concave surface portion 84 is disposed to face a portion of the tapered portion 412 and the lower end portion of the body portion 413 when the cylindrical can 41 is held between the inner mold 71 and the base die 80. That is, the surface of the concave surface portion 84 is a concave surface that presses the outer surface of a portion of the tapered portion 412 of the cylindrical can 41 applied to the lower end portion of the body portion 413.
Further, a vent hole 85 communicating with the inside of the base die 80 is provided substantially at the center of the bottom surface portion 83.

  As shown in FIG. 6, the inner mold 71 is inserted into the cylindrical can 41 by such a bottom portion re-forming apparatus, and the bottom 411 of the cylindrical can 41 together with the inner mold 71 is the outer mold (base die) 80. Between the convex curved surface 74 of the inner mold 71 and the concave curved surface 84 of the outer mold 80 from the outer peripheral edge of the annular convex 112 of the cylindrical can 41 from the body 413 The portion applied to the lower end portion of the is clamped and re-formed into the state shown in FIG.

  The bottom portion 11 of the reshaped can 42 reshaped by the bottom portion remolding apparatus is formed by the can bottom concave portion 111, the annular convex portion 112 and the curved portion 113. The can bottom recess 111 after reshaping has the same shape as the can bottom recess 111 of the cylindrical can 41 before reshaping. The curved portion 113 is formed in a range including the outer peripheral edge portion of the annular convex portion 112 to the lower end portion of the trunk portion 413. Therefore, the height dimension H2 of the bottom portion 11 of the re-formed can 42 is larger than the height dimension H1 of the bottom portion 411 of the cylindrical can 41 shown in FIG. 7. Specifically, the height dimension of the bottom portion 11 having the curved portion 113 of the re-formed can 42 is 3 mm to 10 mm, and the height dimension H2 of the bottom portion 411 having the tapered portion 412 of the cylindrical can 41 is 10 mm to It is 20 mm.

Further, the radius of curvature R2 (the radius of curvature of the outer surface of the reformed can 42) of the curved portion 113 at the bottom 11 of the reformed can 42 formed by the bottom remolding apparatus is larger than the radius of curvature R1 of the bent portion 414. It becomes a radius of curvature. For this reason, the re-formed can 42 has higher column strength than the cylindrical can 41.
Furthermore, as described above, since the print coating process is performed on the body portion 413 of the cylindrical can 41 in the printing and painting process, as shown in FIG. 8, printing is performed up to the upper end portion of the curved portion 113 in the bottom portion 11 of the bottle can 10 A layer is formed.

[Diameter reduction part formation process]
A plurality of forming tools 52 aligned in the circumferential direction of the tool holding portion 53 constituting the reduced diameter portion forming device are sequentially used for the upper end portion of the reformed can 42 formed to the state shown in FIG. While the forming tool 52 is moved along the can axial direction to perform the die necking process, as shown in FIG. 9, the diameter of the upper portion is reduced from the midway position in the height direction of the reformed can 42, and the shoulder is The diameter reduction portion 14 is formed by gradually reducing the diameter of the upper portion of the portion 13 and the shoulder portion 13 thereof.

[Step of forming enlarged diameter portion]
Then, as shown in FIG. 10, the enlarged diameter portion 15 is formed in the vicinity of the opening end portion of the reduced diameter portion 14 formed in the reshaped can 42.
[Curl part formation process]
Next, the opening end is curled to form a curled portion 16 as shown in FIG.

In this embodiment, the cylindrical can 41 is formed by the cylindrical can forming step, and a curved surface is formed such that the portion from the outer peripheral edge of the annular convex portion 112 to the lower end of the body 413 by the bottom portion reforming step is outwardly convex. To form a curved portion 113 with a large radius of curvature. Since the radius of curvature of the curved portion 113 is large, the strength in the axial direction (column strength) can be increased.
Then, since the strength (column strength) in the axial direction of the reformed can 42 is increased, when the reduced diameter portion 14 is formed in the reduced diameter portion forming step, the reformed can 42 is axially formed from the open end side. In the case of being pressed in the direction, the pressing force along the axial direction can be received by the entire curved surface, and concentration of the pressing force on the lower end portion of the body portion 413 can be suppressed. Therefore, the strength in the axial direction of the bottle can 10 can be increased, and the lower end portion of the body 12 can be made difficult to expand.
For example, a cylindrical can was formed as described above using an aluminum alloy plate having a base thickness of 0.475 mm before being formed into a can, and the column strength was measured when the bottom was reformed. The radius of curvature R1 of the bent portion of the cylindrical can was 4 mm, and the radius of curvature R2 of the curved portion of the re-formed can was 12 mm (all in the dimension on the mold). The column strength is the strength when the buckling is caused by pressing in the can axial direction, and it was confirmed that the cylindrical can is 2626 N and the reformed can is 2813 N, and the column strength is improved by the reforming.

Further, in the present embodiment, since the printing is applied before the bottom reforming step, for example, the printing area in the axial direction in the body portion 413 is further compared to the case where the printing painting step is performed after the bottom reforming step. A large size can be taken, and printing can also be performed on the lower end portion (upper end portion of the curved portion 113) of the trunk portion 413 reshaped into a curved surface.
Furthermore, the bottom portion 411 and the body portion 413 are formed by pressing the bottom portion 411 of the cylindrical can 41 with the inner mold 71 and the outer mold (base die 80) in a manner similar to the cylindrical can forming apparatus. The lower end of the can be reshaped. That is, the configuration of the bottom portion re-forming device can be made substantially the same as that of the cylindrical can forming device, and the bottle can manufacturing device can be simplified.

The present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made in the detailed configuration without departing from the spirit of the present invention.
In the above embodiment, the bottle can 10 has the curled portion 16 and the cap 30 is fixed to the curled portion 16. However, the present invention is not limited to this. For example, in the vicinity of the open end of the bottle can 10 The screw part may be formed and sealed by a cap having a screw part screwed to the screw part. Moreover, although the example of the manufacturing method and manufacturing apparatus of the bottle can 10 was shown in the said embodiment, not only this but this invention is applicable also to cans other than a bottle can.

1 container 10 bottle can (can)
11 bottom portion 111 can bottom concave portion 112 annular convex portion 113 curved portion 12 body portion 13 shoulder portion 14 reduced diameter portion 15 enlarged diameter portion 16 curled portion 17 opening 20 cylindrical can forming device 21 punch sleeve 22 dome forming portion 23 die 30 cap 40 cup 41 cylindrical can 411 bottom portion 412 tapered portion 413 body portion 414 bent portion 42 reshaped cylindrical can 43 intermediate formed body 50 bottle shape forming device 51 work holding portion 52 forming tool 53 tool holding portion 54 driving portion 55, 62 Support shaft 56, 63 Disc 57 Holding device 58 Supply part 59 Supply side star wheel 60 Discharge side star wheel 61 Discharge part 70 Inner punch 71 Inner mold 72 Support shaft part 73 Convex part 74 Convex curved part 75 Cylindrical part 76 Concave part 80 Base die (External mold)
81 top surface portion 82 concave portion 83 bottom surface portion 84 concave curved surface portion

Claims (4)

The metal plate is squeezed and ironed to have, at the bottom, an annular convex portion extending in the circumferential direction around the can axis, and a tapered surface portion extending from the outer peripheral edge of the annular convex portion. A cylindrical can forming step of forming a cylindrical can connected to a portion via a bending portion;
A bottom portion re-forming step of re-forming a portion from the tapered portion to the lower end portion of the body portion;
Equipped with
In the bottom portion re-forming step, a portion of the tapered portion to the lower end portion of the body portion is re-formed into a curved surface which is outwardly convex with a curvature radius larger than the curvature radius of the bent portion. Production method.   The can manufacturing method according to claim 1, further comprising a diameter reducing portion forming step of forming a diameter reducing portion formed by reducing a diameter of a portion on the opening end portion side of the cylindrical can after the bottom portion reforming step. Method.   The method for manufacturing a can according to claim 1 or 2, further comprising a printing step of printing around the body part between the cylindrical can forming step and the bottom part re-forming step. The bottom portion has an annular convex portion extending in the circumferential direction around the can axis, and a tapered surface portion extending from the outer peripheral edge of the annular convex portion, and the upper end of the tapered surface portion is connected to the trunk through a bending portion. An internal mold having a convex surface which is inserted into a cylindrical can and supports from the inside the portion extending from the tapered surface to the lower end of the body, and the cylindrical can supported from the inside by the internal mold And an outer mold having a concave surface for pressing from the outside a portion from the tapered portion to the lower end portion of the body portion,
The apparatus for manufacturing a can, wherein the convex curved surface of the inner mold and the concave curved surface of the outer mold are formed to have a radius of curvature larger than the radius of curvature of the bent portion.

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