JP6948843B2 - How to make cans - Google Patents

Description

The present invention relates to a method for producing a bottomed cylindrical can used for a can body such as a two-piece can or a bottle can filled with contents such as a beverage.

As a can body filled and sealed with contents such as beverages, a bottomed cylindrical can having a can body (wall) and a can bottom (bottom) and a disk-shaped can wound around the open end of the can. Two-piece cans with a can lid are known. Specifically, the can is a DI can, and "DI" is an abbreviation for Drawing & Ironing. Also, bottle cans in which a cap is screwed to the open end of the can are well known.
The can used for such a can body is formed into a bottomed tubular shape by subjecting a plate material of an aluminum alloy material to a cutting step (squeezing step) and a DI step (squeezing ironing step).

Further, as the can body, a can having a can body provided in a straight shape along the can axis direction is widely used, but the design of the can body is improved and the ease of holding (grip property) is improved. In order to do so, cans in which the can body is partially deformed have come to be used.
For example, Patent Document 1 discloses a can in which a lower squeezing portion and an upper squeezing portion having a diameter smaller than that of the middle portion of the can body are formed by drawing the outer periphery of the vicinity of the bottom portion and the shoulder portion of the metal can. There is. Further, in Patent Document 2, after performing a diameter reduction process to reduce the diameter of the can (bottomed cylindrical body) above a predetermined position in the axial direction (open end side), the reduced diameter portion is left. A can having a constricted portion having a diameter smaller than that of other portions in the can body is disclosed by subjecting the can body to a diameter-expanding process in the state. Further, in Patent Document 3, after the diameter-expanding process is performed from one end to the other end of the can body (body portion) of the can (container), the drawing process is performed above the enlarged diameter portion while leaving the enlarged diameter portion. The given can is disclosed.

Japanese Unexamined Patent Publication No. 2000-218333 Japanese Unexamined Patent Publication No. 2003-305523 Japanese Unexamined Patent Publication No. 2008-20055

As described in Patent Documents 1 to 3, deformed cans in which the can body is partially deformed have come to be manufactured, but they are manufactured with such diameter reduction processing and diameter expansion processing. Since the deformed can is prone to wrinkles, cracks, and breaks in the processed portion, which makes processing very difficult, the shape that can be molded is limited.
That is, in the conventional can manufacturing method, if a process of expanding the diameter in a long deformation region along the can axial direction (axial direction of the can body) or a process of causing a large deformation by a large amount of change in diameter is performed, the can body is subjected to processing. Since the friction between the can body and the mold becomes large, there has been a problem that the meat of the can body is stretched to generate molding marks, wrinkles, cracks, etc. in the processed portion. In addition, the coating film applied to the inner and outer surfaces may also be damaged. Furthermore, as the weight of the can body is being reduced, it is required to make the can body thinner, which makes it more difficult to increase the diameter. Therefore, the shape of the can that can be molded is very limited, which has been a constraint on the design of the can body.

The present invention has been made in view of such circumstances, and it is possible to stably perform a diameter-expanding process for causing a large amount of change in diameter in a long deformation region along the can axis direction, and to the can body. It is an object of the present invention to provide a can manufacturing method capable of providing a can having a beautiful appearance by preventing the occurrence of molding marks and wrinkles.

The present invention includes a can body and a can bottom, and has a bottomed tubular shape in which the outer diameter difference between the lower part of the can body and the upper part of the can body is 2% or more and 18% or less with respect to the outer diameter of the lower part. In the method for manufacturing a can, the diameter-expanded portion provided between the lower portion of the can body arranged on the can bottom side and the upper portion arranged on the opening end side is along the can axis direction. A diameter-expanding portion molding step of molding a diameter-expanding portion that gradually increases in diameter from the lower side to the upper side of the can cylinder is provided, and the diameter-expanding portion molding step is performed on a diameter-expanding mold inside the can cylinder. To increase the diameter of the entire area from the opening end of the can body to the planned diameter expansion portion by moving the can body relative to the can axis, the processing diameter of the diameter expansion mold is increased. The diameter is increased in steps of 1.0 mm or less and divided into multiple times, and each time the diameter expansion process is performed, the local diameter expansion portion formed by each diameter expansion mold is formed from the lower side to the upper portion. The enlarged diameter portion is formed while shifting the position toward the side.

In the method for manufacturing a can according to the present invention, in the diameter-expanding portion molding step, the diameter-expanding portion is repeatedly molded a plurality of times, and the locally expanded portion is molded while shifting the position from the lower side to the upper side by each molding die. These locally enlarged diameter portions are connected to form the enlarged diameter portion. Further, in the diameter-expanding portion forming step, the processing diameter of the diameter-expanding die is gradually increased without restraining the outer peripheral surface of the can body, and the diameter-expanding dies having different processing diameters are used in order. Performs diameter expansion processing multiple times. In this way, each diameter expansion process is performed without restraining the outer peripheral surface (outside) of the can body. Therefore, when the diameter expansion mold is inserted into the can body, the diameter of the can body is expanded. While being stretched in the circumferential direction by the mold and moving outward in the radial direction (diameter expansion direction), the can body is compressed as the diameter expansion mold moves in the can axis direction. The meat of the can body is pulled toward the lower side in the can axis direction and is compressed. Then, in the diameter-expanding portion molding step, the diameter-expanding portion is formed by performing the diameter-expanding processing a plurality of times, and by reducing the diameter-expanding amount (processing amount) in one diameter-expanding processing, the can body is formed. To balance the thinning of the meat by moving it outward in the radial direction and stretching it in the circumferential direction, and the thickening by moving the meat of the can body to the lower side in the can axis direction. It is possible to suppress the thinning of the plate thickness (wall thickness) of the can body in the processed part due to the diameter expansion processing. Then, by repeating the diameter-expanding process a plurality of times, it is possible to form a diameter-expanded portion having a large diameter-expanded portion by connecting the local diameter-expanded portions.
When the diameter expansion amount of the can body to be processed in one diameter expansion process exceeds 1 mm, the meat of the can body is stretched in the circumferential direction to reduce the thickness (thickness reduction amount) of the can body. As the meat is moved toward the lower side in the can axis direction, the amount of meat increase (thickness increase amount) cannot keep up. That is, the amount of reduction in the height of the can body cannot keep up with the amount of processing in the radial direction (diameter expansion amount), and the processed portion of the can body is reduced in thickness, so that the processed portion is liable to crack. On the other hand, by setting the diameter expansion amount at one time to 1 mm or less, it is possible to sufficiently secure the movement amount (thickness increase amount) of the meat in the can body in the can axis direction corresponding to the processing amount in the radial direction. It is possible to balance the thinning of the meat by stretching it in the circumferential direction and the thickening by moving the meat of the can body to the lower side in the can axis direction, and the can body of the processed part. It is possible to prevent the thickness of the plate from being reduced and cracks from occurring in the processed portion. Therefore, a large diameter-expanded portion having a large outer diameter difference of 2% or more and 18% or less with respect to the outer diameter of the lower portion can be stably formed.

That is, in the diameter-expanded portion forming step of the can manufacturing method of the present invention, the height of the can body in the can axis direction is gradually reduced in each of the plurality of diameter-expanding processes.

In each diameter expansion process, the height of the can body (height in the can axis direction) is gradually reduced by moving the meat of the can body toward the lower side in the can axis direction. In this way, by expanding the diameter while gradually reducing the height of the can body, the meat of the can body moves outward in the radial direction and is stretched in the circumferential direction to reduce the wall thickness and the can. It is possible to balance with the thickening by moving the meat of the body to the lower side in the can axis direction, and the thickness of the can body of the processed part is reduced and the processed part is cracked. It can be avoided. Therefore, in the can manufacturing method according to the present invention, it is possible to avoid damage such as wrinkles and cracks in the processed portion, and it is possible to stably form a diameter-expanded portion having a large diameter-expanded portion, and a greatly inclined diameter-expanded portion or a diameter-expanded portion. It is possible to form a diameter-expanded portion having various shapes such as a diameter-expanded portion inclined over a wide range. Further, in the can manufacturing method according to the present invention, the diameter-expanded portion can be formed only by the diameter-expanding process without the diameter-reducing process, and the process can be simplified.

In the diameter-expanding portion molding step of the can manufacturing method of the present invention, each time the diameter-expanding process is performed, the locally-diameter-expanded portion is molded by the diameter-expanding die and formed in the previous diameter-expanding process. Shape the local enlarged diameter part.

It is possible to prevent indentations from being left on the can body by shaping the local diameter-expanded portion formed in the previous diameter-expanding process each time the diameter-expanding process is performed. Therefore, it is possible to form the enlarged diameter portion in which the connecting portions of the local enlarged diameter portions are smoothly connected, and it is possible to improve the cosmetic appearance of the can.

In the diameter-expanding portion molding step of the can manufacturing method of the present invention, an engaging shaft portion that engages with the inner peripheral surface of the lower portion of the can body is provided at the tip portion of the diameter-expanding mold. It is preferable to align the diameter-expanding mold with the can body by inserting the engaging shaft portion into the lower part of the can body.

By providing engaging shafts for each of the different diameter-expanding dies and aligning these engaging shafts with the lower part of the can body that is not subjected to diameter-expanding processing, it is repeated a plurality of times. In the diameter-expanding process, the diameter-expanding die and the can body can be accurately aligned, and the can body can be processed with high accuracy without any deviation.

According to the present invention, it is possible to stably perform a diameter-expanding process that gently expands the diameter in the direction of the can axis, prevent the occurrence of molding marks and wrinkles on the can body, and give the can a beautiful appearance. can do.

It is a half cross-sectional view which shows the can manufactured by the manufacturing method of the can which concerns on 1st Embodiment of this invention. It is a flowchart explaining the manufacturing method of the can which concerns on 1st Embodiment of this invention. It is a schematic diagram explaining the cupping process, DI processing and trimming processing of the can manufacturing method which concerns on 1st Embodiment of this invention. It is sectional drawing of the main part explaining the diameter-expanding part molding process in the can manufacturing method which concerns on 1st Embodiment of this invention, and shows the state which arranged the diameter-expanding die separated above the can. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 1st Embodiment of this invention, and shows the state of the 1st diameter-expanding process. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 1st Embodiment of this invention, and shows the state of the 2nd diameter-expanding process. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 1st Embodiment of this invention, and shows the state of the 3rd diameter-expanding process. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 1st Embodiment of this invention, and shows the state of the 4th diameter-expanding process. It is sectional drawing of the main part of the can body explaining the relationship between each diameter expansion die and a can. It is a half cross-sectional view which shows the can manufactured by the manufacturing method of the can which concerns on 2nd Embodiment of this invention. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 2nd Embodiment of this invention, and shows the state of the 5th diameter-expanding process. It is a half cross-sectional view which shows the can manufactured by the manufacturing method of the can which concerns on 3rd Embodiment of this invention. It is sectional drawing of the main part explaining the diameter-expanded part molding process in the can manufacturing method which concerns on 3rd Embodiment of this invention, and shows the state of the 5th diameter-expanding process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
The can manufactured in the can manufacturing method according to the first embodiment of the present invention is formed by molding, for example, an aluminum plate having a size of 0.30 mm to 0.50 mm, and is filled with contents such as beverages. It is used for sealed two-piece cans and bottle cans. In the present embodiment, the can 30 (see FIG. 1) used for the two-piece can will be taken as an example for description.

The can body of the two-piece can includes a bottomed cylindrical can 30 as shown by a two-dot chain line in FIG. 1 and a disk-shaped can lid (not shown) wound around the open end of the can 30. Is provided. Specifically, the can 30 is a DI can, and "DI" is an abbreviation for Drawing & Ironing. The can 30 manufactured by the can manufacturing method of the present embodiment is used for cans having a can body diameter / opening diameter of 211/204 with a nominal diameter, but is not limited thereto. Other than that, for example, it may be applied to 211/206 diameter cans, 204/200 diameter cans having a smaller outer diameter, 204/202 diameter cans, and the like.

The can 20 shown by a solid line in FIG. 1 has undergone a diameter-expanded portion forming step described later and represents a state before the necking step. As shown by the alternate long and short dash line in FIG. 1, the can 30 has a neck portion 13 having a smaller diameter toward the upper side and an annular flange portion 15 arranged above the neck portion 13. It is formed.

As shown in FIG. 1, the can 20 includes a cylindrical can body (wall) 11 and a dome-shaped can bottom (bottom) 12. In FIG. 1, the can body 11 and the can bottom 12 are arranged coaxially with each other, and in the present embodiment, these common axes will be referred to as a can axis O and will be described. Further, among the directions along the can shaft O (can shaft O direction), the direction from the opening end 11a of the can body 11 toward the can bottom 12 side is downward, and the direction from the can bottom 12 toward the opening end 11a is upward. That is. Further, the direction orthogonal to the can axis O is referred to as a radial direction, the direction of approaching the can axis O is referred to as the inside (inward) of the radial direction, and the direction away from the can axis O is the radial direction. It is called the outside (outside). Further, the direction of orbiting around the can shaft O is called the circumferential direction.

The upper end of the can body 11 is an open end 11a that opens to the outside of the can 20. The contents are filled into the can 20 through the open end 11a. Further, the lower end portion of the can body 11 is closed by the can bottom 12.

As shown in FIG. 1, the can body 11 has an outer diameter Dt of the upper portion 21 arranged on the opening end portion 11a side of the outer diameter Db of the lower portion 23 arranged on the can bottom 12 side of the can body. A large diameter portion 22 is provided between the lower portion 23 and the upper portion 21, and the diameter gradually increases from the lower 23 side to the upper 21 side of the can body 11 along the can axis O direction. Has been done. That is, the upper portion 21 and the enlarged diameter portion 22 of the can cylinder 11 are formed so as to bulge outward in the radial direction from the lower portion 23 of the can cylinder 11, and extend to the entire circumference of the can cylinder 11 along the circumferential direction. It forms a ring. Further, in the vertical cross-sectional view of the can 20 shown in FIG. 1, the lower end side of the enlarged diameter portion 22 is a concave curved surface portion 25 having a concave curved surface shape which is concave toward the inside of the can body 11 (inside in the radial direction). The upper end side of the enlarged diameter portion 22 is a convex curved surface portion 24 having a convex curved surface shape that is convex toward the outside (outside in the radial direction) of the can body 11. The upper end of the lower portion 23 of the can body 11 is connected to the lower end of the concave curved surface portion 25, and is provided continuously downward from the lower end of the enlarged diameter portion 22 in a straight line. Further, the lower end of the upper portion 21 of the can body 11 is connected to the upper end of the convex curved surface portion 24, and is provided continuously upward from the upper end of the enlarged diameter portion 22 in a straight line.

Further, the lower portion 23 of the can body 11, the enlarged diameter portion 22 (concave curved surface portion 25 and the convex curved surface portion 24), and the upper portion 21 are smoothly connected to each other and are smoothly connected without forming a step between them. ing. Specifically, in the vertical cross-sectional view shown in FIG. 1, the upper end of the lower portion 23 is provided in contact with the lower end of the concave curved surface portion 25 of the enlarged diameter portion 22, and the lower portion 23 serves as a tangent line to the concave curved surface portion 25. There is. Further, the lower end of the upper portion 21 is provided in contact with the upper end of the convex curved surface portion 24 of the enlarged diameter portion 22, and the upper portion 21 is a tangent line of the convex curved surface portion 24.

The outer diameter Db of the lower portion 23 of the can body 11 is, for example, 52 to 67 mm. Further, the difference in outer diameter between the upper portion 21 and the lower portion 23 of the can body 11, that is, the width at which the upper portion 21 expands outward in the radial direction with respect to the lower portion 23 is 2% or more and 18% or less, and the outer diameter of the upper portion 21. Dt is, for example, 53 mm to 79 mm. In the can 10 of the present embodiment, the diameter expansion ratio (outer diameter difference) is about 14% (the diameter difference is about 8 mm, and the one-sided width g0 of the diameter is about 4 mm).

Further, in the vertical cross-sectional view of the can 20 shown in FIG. 1, the radius of curvature of the concave curved surface portion 25 of the enlarged diameter portion 22 as a product (the radius of curvature on the outer peripheral surface of the concave curved surface portion 25) is in the range of, for example, 50 mm to 200 mm. The radius of curvature of the convex curved surface portion 24 of the enlarged diameter portion 22 (the radius of curvature on the outer peripheral surface of the convex curved surface portion 24) is, for example, in the range of 100 to 500 mm. However, the radius of curvature is not limited to the above numerical range, and the enlarged diameter portion 22 may be provided in a tapered shape that increases in diameter toward the upper side in the can axis O direction instead of a curved surface.
In the case of the can 20 of the first embodiment shown in FIG. 1, the radius of curvature of the concave curved surface portion 25 in the enlarged diameter portion 22 of the can body 11 is 100 mm, and the radius of curvature of the convex curved surface portion 24 is 300 mm. 25 is formed from the connection end with the lower portion 23 of the can body 11 to the lower end portion of the enlarged diameter portion 22, and most of the enlarged diameter portion 22 is formed by the convex curved surface portion 24 except for the lower end portion. ..

The can bottom 12 is located on the can shaft O, and has a dome portion 12a formed so as to bulge upward (inside the can cylinder 11), an outer peripheral edge portion of the dome portion 12a, and the can cylinder 11. It is provided with a heel portion 12c for connecting to the lower end portion of the dome.
In the vertical cross-sectional view shown in FIG. 1, the heel portion 12c is gradually inclined inward in the radial direction from the lower end portion of the can body 11 toward the bottom. Further, in this vertical cross-sectional view, the connecting portion of the heel portion 12c with the lower end portion of the can body 11 (that is, the upper end portion of the heel portion 12c) has a convex curved shape protruding outward from the can body 11.

Further, the connecting portion between the dome portion 12a and the heel portion 12c on the can bottom 12 is such that the can 20 is in an upright posture (a posture in which the open end portion 11a of the can body 11 faces upward as shown in FIG. 1). The ground contact portion 12b is in contact with the ground contact surface when it is mounted on the ground contact surface (mounting surface). The ground contact portion 12b projects downward at the bottom of the can 12 and forms an annular shape extending along the circumferential direction.

The straight line (two-point chain line) represented by the reference numeral H in FIG. 1 passes through the center of the radius of curvature of the convex curve formed by the upper end portion of the heel portion 12c and represents a virtual horizontal plane perpendicular to the can axis O.
In the present specification, of the peripheral wall (outer peripheral wall) of the can 20, the portion located above the virtual horizontal plane H is referred to as the can body 11, and the portion located below the virtual horizontal plane H is referred to as the can bottom 12. There is. Specifically, on the peripheral wall of the can 20, the portion of the can bottom 12 located below the virtual horizontal plane H is the heel portion 12c.

The neck portion 13 of the can 30, which is formed by subjecting the can 20 to a necking step and a flanging step, is arranged adjacent to a tapered portion 51 whose diameter gradually decreases toward the top and below the tapered portion 51. It has a convex curved surface portion 52 that is convex toward the outside of the body 11, and a concave curved surface portion 53 that is adjacently arranged above the tapered portion 51 and is concave toward the inside of the can body 11. Further, the tapered portion 51, the convex curved surface portion 52, and the concave curved surface portion 53 each form an annular shape extending over the entire circumference of the can body 11 in the circumferential direction. The convex curved surface portion 52, the tapered portion 51, and the concave curved surface portion 53 are smoothly connected to each other. Specifically, in the vertical cross-sectional view of the can 30 shown in FIG. 1, the tapered portion 51 is a tangent line that is in contact with the convex curved surface portion 52 and the concave curved surface portion 53 and connects them.

The linear portion on the lower end side of the upper portion 21 and the convex curved surface portion 52 of the neck portion 13 are smoothly connected to each other. Further, the concave curved surface portion 53 of the neck portion 13 and the flange portion 15 arranged adjacent to the concave curved surface portion 53 are also smoothly connected.
Further, the lower portion of the can body 11 is smoothly connected to the upper end portion of the heel portion 12c described later of the can bottom 12.

Next, with reference to FIGS. 2 to 8, an example of a method of manufacturing a bottomed tubular can 20 having a diameter-expanded portion 22 from a plate material of an aluminum alloy material by the can manufacturing method of the present embodiment will be described. ..
As shown in FIG. 2, the can 20 is manufactured through a punching and cutting step, a DI step, a trimming step, a printing step, a painting step, and a diameter-expanded portion forming step in this order. Further, the can 30 is manufactured by subjecting the can 20 manufactured through the diameter-expanded portion forming step to the necking step and the flanging step in this order.

[Punching process and cupping process (drawing process)]
An ingot made of an aluminum alloy material is hot-rolled, cold-rolled, and annealed to form an intermediate plate material having a predetermined plate thickness, and then cold-finish rolling is performed on the intermediate plate material to obtain a final plate thickness. By preparing a material and drawing (copping) the rolled material while punching it with a coupling press, a relatively large diameter and shallow cup-shaped body W1 is formed as shown in FIG. 3 (a).

[DI process (squeezing ironing process)]
Next, the cup-shaped body W1 is subjected to DI processing (re-squeezing and ironing processing) by a DI processing device, and as shown in FIG. Mold into can W2. By this DI processing, the can bottom 12 of the can W2 is formed into the can bottom shape of the final can 20.

More specifically, the DI processing apparatus includes one redrawing die having a circular through hole for redrawing, and a plurality of pieces having a circular through hole coaxially arranged with the redrawing die (for example,). 3) ironing dies (squeeze dies) and coaxial with the ironing dies, can be fitted inside each through hole of each of the above ironing dies, and can be moved in the axial direction of the die. A cylindrical or columnar punch sleeve and a cylindrical cup holder sleeve fitted to the outside of the punch sleeve are provided.

In the redrawing process by the DI processing device, the cup-shaped body W1 is placed between the punch sleeve and the redrawing die, the cup holder sleeve and the punch sleeve are advanced, and the cup holder sleeve cups on the end face of the redrawing die. The punch sleeve pushes the cup-shaped body W1 into the through hole of the re-drawing die while pressing the bottom surface of the shaped body W1 to perform the cup pressing operation.
As a result, a re-drawn cup-shaped body (not shown) having a predetermined inner diameter is formed. Subsequently, the re-drawn cup-shaped body is sequentially passed through a plurality of ironing dies and gradually ironed, and the peripheral wall of the cup-shaped body is squeezed to extend the peripheral wall and increase the peripheral wall height. At the same time, the wall thickness is reduced to form a bottomed cylindrical can W2.

The bottom of the can W2 that has been ironed is formed into the above-mentioned dome shape by the punch sleeve pushing further forward and pressing the bottom (the portion that becomes the can bottom 12) against the bottom molding die. The can W2 is work-hardened by squeezing the peripheral wall as described above, and the strength is increased.

As shown in FIG. 3B, the open end portion 11a of the can W2 that has undergone the cupping step and the DI step is formed in a concavo-convex shape (concave-convex wave shape) that undulates up and down in the circumferential direction. It should be noted that this uneven wave shape is given from the time when the plate material W is formed into the cup-shaped body W1.
Of the upper end edge of the open end portion 11a having a concave-convex wave shape, a portion (convex portion) having a mountain protruding upward is called an ear 19. A plurality of ears 19 are formed along the circumferential direction at the open end 11a. These ears 19 are caused, for example, by the crystallographic anisotropy of an aluminum alloy.

[Trimming process]
Next, the open end 11a of the can W2 is trimmed.
That is, since the open end 11a of the can W2 formed by the DI processing apparatus has the ears 19 formed and the height is non-uniform, the open end 11a of the can W2 is cut and trimmed. , As shown in FIG. 3C, the height of the peripheral wall along the can axis O direction at the open end 11a of the can body 11 is evenly aligned over the entire circumference. As a result, a trimmed can 10 having no ear 19 at the open end 11a of the can body 11 (the ear 19 has been cut off) can be obtained. This trimming step is performed at the end of molding in the DI step.
The height of the can 10 in the can axis O direction (height from the lower end of the can bottom 12 (grounding portion 12b) to the upper end of the opening end 11a) is, for example, about 124 mm in the case of a 350 ml can, and is 500 ml. In the case of a can, it is about 168 mm.

[Printing process, painting process]
The can 10 is washed to remove lubricating oil and the like, then surface-treated and dried, and then outer surface printing and outer surface coating are applied, and then inner surface coating is applied. Specifically, in the printing process, the printing ink is used to print the outer surface of the can body 11 of the can 10.
Next, in the painting process, the outer surface is painted and then the inner surface is painted. Specifically, for example, a polyester-based paint is used to paint the outer surface of the can body 11 of the can 10, and the can 10 coated on the outer surface is heated and dried in an oven. When the can body 11 is heated and dried by heating, a transport pin extending in a substantially horizontal direction is inserted from the open end 11a of the can body 11 toward the inside, and the transport pin supports the can 10 while supporting the can 10. It is moved by a drive mechanism equipped with a chain, a motor, and the like. Next, the inner surfaces of the can body 11 and the bottom 12 of the can 10 are painted using, for example, an epoxy-based paint, and the can 10 coated on the inner surface is heated and dried in an oven while being conveyed by a conveyor.

[Diameter expansion part molding process]
Next, as shown in FIG. 4, the diameter-expanding planned portion 29 located between the lower portion 23 and the upper portion 28 of the can body 11 of the can 10 is located in the can shaft O direction as shown in FIG. Along, the diameter-expanded portion 22 having a larger diameter is formed from the lower portion 23 side to the upper portion 21 side, and the upper portion 21 arranged adjacent to the diameter-expanded portion 22 is formed by expanding the diameter outward in the radial direction. ..

In the diameter-expanded portion molding step, in order to mold the diameter-expanded portion 22 having a large outer diameter difference (diameter expansion ratio) connecting the lower portion 23 and the upper portion 21, the processing diameter is different inside the can body 11 of the can 10. A plurality of diameter-expanding dies are fitted in order from the side with the smallest processing diameter, and the diameter-expanding processing is performed a plurality of times. At this time, one diameter expansion process is performed with a diameter expansion amount of 1 mm or less. For example, when the upper portion 21 is expanded outward in the radial direction with respect to the lower portion 23 so that the diameter expansion amount is 6 mm (diameter expansion rate 10%), the diameter expansion amount is increased by one diameter expansion process. When is set to 0.5 mm, the diameter-expanded portion 22 having an outer diameter difference (diameter expansion amount) of 6 mm can be formed by performing a total of 12 diameter expansion processes. Hereinafter, in the present embodiment, for simplification of the description, as shown in FIGS. 4 to 8, four diameter-expanding dies 40A to 40D having different processing diameters are used, and the diameter-expanding portion 22 is rotated four times. The description will be given by taking as an example the case where the diameter-expanded portion 22 and the upper portion 21 are formed after four times of diameter-expanding processing.

Each of the diameter-expanding dies 40A to 40D is specifically composed of a first punch 40A, a second punch 40B, a third punch 40C, and a fourth punch 40D that are fitted inside the can body 11, and the diameter-expansion processing is performed. Is performed by sequentially using punches 40A to 40D in which the processing diameter is gradually increased without restraining the outer peripheral surface of the can body 11. Hereinafter, the same reference numerals 40A to 40D as those for the diameter-expanding die are used for the punch.
The diameter of the can body 11 that is expanded by each of the punches 40A to 40D is 1 mm or less, and the diameter of the can body 11 that is expanded by the punches 40A to 40D is gradually increased by 1 mm or less. Perform processing.

Specifically, in each diameter expansion process, as shown in FIGS. 4 to 8, the can 10 and the punches 40A to 40D are relatively close to each other (relatively move) in the can axis O direction, and the inside of the can body 11 is moved. By inserting the punches 40A to 40D into the can body 11, the entire region (upper part 28 and planned diameter-expanding portion 29) from the opening end portion 11a of the can body 11 to the planned diameter-expanding portion 29 is expanded in diameter. Then, this diameter-expanding process is performed in a plurality of times while gradually increasing the processing diameter of the punches 40A to 40D, and the locally-diameter-expanded portion processed in one molding is shown in the order of reference numerals 31 to 34. As described above, the can body 11 is formed while shifting its position from the lower 23 side to the upper 28 side.

Further, as shown in FIG. 9, the central axes of the punches 40A to 40D are arranged coaxially with the can axis O. A columnar engaging shaft portion 41 that engages with the inner peripheral surface of the lower portion 23 of the can body 11 is provided at the respective tip portions of the punches 40A to 40D, and the engaging shaft portion 41 can be used as a can. By inserting the punches 40A to 40D into the lower portion 23 of the body 11, the can bodies 11 are aligned with each other. Further, in each of the punches 40A to 40D, molding portions 42a to 42d corresponding to the locally expanded diameter portions 31 to 34 are formed continuously on the engaging shaft portion 41 over the entire circumference in the circumferential direction, and further, the molding portions 42a are formed. Cylindrical linear forming portions 43a to 43d are continuously provided in ~ 42d.

In the molded portions 42a to 42d of the punches 40A to 40D, the portion for forming the concave curved surface portion 25 of the enlarged diameter portion 22 is formed in a concave curved surface shape, and the portion for forming the convex curved surface portion 24 of the enlarged diameter portion 22 is formed. It is formed in a convex curved surface. Specifically, the radius of curvature of the portion of the molded portions 42a to 42d for molding the concave curved surface portion 25 is set to a large concave R of about 100 mm, and the radius of curvature of the portion for forming the convex curved surface portion 24 is set to a large convex R of about 300 mm. Is set to. Further, among the punches 40A to 40D, the molding portions 42a to 42c of the punches 40A to 40C have a connection portion with the linear molding portions 43a to 43c formed on the R surface 46a to 46c having a radius of curvature of 10 mm to 15 mm. The surfaces 46a to 46c are smoothly connected. Further, among the punches 40A to 40D, the molding portion 42d of the fourth punch 40D having the largest processing diameter is continuously and smoothly connected to the linear molding portion 43d. The outer diameter differences g1 to g4 of the linearly formed portions 43a to 43d of the punches 40A to 40D are provided to be 1 mm or less.

The tip side of each of the punches 40A to 40D arranged adjacent to the lower end of the engaging shaft portion 41 is provided with a tapered tip relief portion 44 whose diameter gradually decreases toward the lower side in the can shaft O direction. The engaging shaft portion 41 and the tip relief portion 44 are smoothly connected by an R surface 47 having a radius of curvature of 10 mm to 15 mm. On the other hand, the proximal end side of the punches 40A to 40D arranged adjacent to the upper ends of the linear forming portions 43a to 43d is provided with a diameter reduced inward in the radial direction from the linear forming portions 43a to 43d. ~ 45d is formed.

Of the punches 40A to 40D, the first punch 40A for molding the local diameter-expanded portion 31 is a diameter-expanded molding portion in which the entire area of the molding portion 42a forms the local diameter-expanded portion 31 as shown in FIGS. 5 and 9. The diameter is 48a, and the molding surface of the diameter-expanded molding portion 48a is provided in a curved surface shape that gradually increases in diameter in accordance with the local diameter-expanded portion 31 and changes from a concave surface to a convex surface. On the other hand, the second punch 40B, which forms the local diameter-expanding portion 32 continuous with the local diameter-expanding portion 31, forms the local diameter-expanding portion 32 on the upper side of the molding portion 42b, as shown in FIGS. 6 and 9. A diameter-expanded molding portion 48b is provided, and a shaping portion 49b for shaping the local diameter-expanding portion 31 already formed by the first punch 40A is provided on the lower side. The molding surface of the diameter-expanded molding portion 48b is provided in a convex shape in which the diameter gradually increases upward in accordance with the local diameter-expanding portion 32, and the shaping surface of the shaping portion 49b is curved corresponding to the local diameter-expanding portion 31. It is provided in a planar shape. That is, the shaped surface of the shaping portion 49b is formed in the same shape as the molding surface of the diameter-expanded molding portion 48a of the first punch 40A. As a result, when the local diameter-expanding portion 32 is formed by the second punch 40B, the local diameter-expanding portion 32 is formed in the planned diameter-expanding portion 29 by the diameter-expanding molding portion 48b, and the shaping portion 49b is subjected to the previous diameter-expanding process. The shape of the local diameter-expanded portion 31 is adjusted by abutting on the inner peripheral surface of the locally-expanded portion 31 formed in 1. Therefore, the local diameter-expanding portion 32 is smoothly connected to the local diameter-expanding portion 31, and it is possible to prevent indentations from being left at the connecting portion between the local diameter-expanding portion 31 and the local diameter-expanding portion 31.

Similarly, as shown in FIGS. 7 and 9, the molding portion 42c of the third punch 40C is provided with a diameter-expanding molding portion 48c having a molding surface for molding the local diameter-expanding portion 33 on the upper side. A shaping portion 49c having a shaping surface having the same shape as the molding surface of the diameter-expanded molding portion 48b of the second punch 40B is provided on the lower side. The molding surface of the diameter-expanded molding portion 48c is provided in a convex shape that gradually expands in diameter in accordance with the local diameter-expanding portion 33, and the shaping surface of the shaping portion 49c extends to the local diameter-expanding portions 31 to 32. It is provided in a curved surface corresponding to the region.

Further, as shown in FIGS. 8 and 9, the molding portion 42d of the fourth punch 40B is provided with a diameter-expanding molding portion 48d having a molding surface for molding the local diameter-expanding portion 34 on the upper side, and is provided on the lower side. Is provided with a shaping portion 49d having a shaping surface having the same shape as the molding surface of the diameter-expanded molding portion 48c of the third punch 40C. The molding surface of the diameter-expanded molding portion 48d is provided in a convex shape that gradually expands in diameter in accordance with the local diameter-expanding portion 34, and the shaping surface of the shaping portion 49d extends to the local diameter-expanding portions 31 to 33. It is provided in a curved surface corresponding to the region.

Then, in the diameter expansion processing, first, as shown in FIG. 4, the first punch 40A having the smallest processing diameter is arranged at a distance above the can 10, and then the can 10 and the first punch 40A are placed on the can shaft O. As shown in FIG. 5, the first punch 40A is made to enter the can body 11 of the can 10 from the opening end portion 11a while being relatively approached (relatively moved) in the direction. At this time, in the diameter-expanding process using the first punch 40A, the diameter of the can body 11 is to be increased from the open end 11a of the can body 11 while reducing the height (can height, height) of the can body 11 in the can axis O direction. Expand the entire area up to 29

In the present embodiment, the first punch 40A is moved closer (advanced) to the can 10 in the can axis O direction. At this time, the engaging shaft portion 41 of the first punch 40A is first fitted inside the can body 11, and the can shaft of the can 10 and the central shaft of the first punch 40A are aligned. Then, with the can 10 and the first punch 40A aligned in this way, as shown in FIG. 5, the first punch 40A is further moved forward to enter the inside of the can body 11. Along the diameter-expanded molded portion 48a continuously provided from the engaging shaft portion 41, the region from the opening end portion 11a of the can body 11 to the lower end of the planned diameter-expanding portion 29 is expanded outward in the radial direction to expand the diameter. Processing will be applied. Then, a local diameter-expanding portion 31 continuous with the lower portion 23 is formed at the lower end of the diameter-expanding portion 29.

At this time, since the outer peripheral surface (outside) of the can body 11 is not restrained at all, when the first punch 40A is made to enter the inside of the can body 11 and moved forward, the meat of the can body 11 is pulled in the circumferential direction. While it is extended and moves outward in the radial direction (diameter expansion direction), a force is applied in the direction in which the can body 11 is compressed toward the lower portion 23 in the can axis O direction as the first punch 40A moves forward. In response to this, the meat of the can body 11 is brought toward the lower 23 side in the can axis O direction. As a result, the can body 11 is compressed, and the height of the can body 11 (the height of the can) becomes smaller after the processing than before the diameter expansion processing. Further, since the processing amount (diameter expansion amount g1) by the first punch 40A is a slight diameter expansion amount of 1 mm or less on the outer side in the radial direction, the meat of the can body 11 moves to the outer side in the radial direction to rotate. The thickness of the can body 11 in the processed portion is reduced due to the combination of the thinning by stretching in the direction and the thickening by moving the meat of the can body 11 toward the lower 23 side in the can axis O direction. Meat is suppressed. Therefore, in the diameter-expanding process using the first punch 40A, the local diameter-expanded portion 31 is formed while reducing the height of the can body 11 without causing an extreme thinning in the plate thickness of the can body 11 in the processed portion. can.
After the diameter expansion process is performed by the first punch 40A, the first punch 40A is moved apart (backward) with respect to the can 10 in the can axis O direction. Then, the first punch 40A is separated from the inside of the can body 11 and returned to the original position (processing preparation position, standby position).

After forming the local diameter-expanded portion 31, the second punch 40B, which has a larger processing diameter by the diameter-expanded amount g2 than the first punch 40A, is inserted into the can body 11 to expand the diameter in the same manner as the first punch 40A described above. After processing, as shown in FIG. 6, the local diameter-expanding portion 32 at a position shifted upward from the local diameter-expanding portion 31 is formed by the diameter-expanding molding portion 48b, and the local portion formed by the previous diameter-expanding processing is formed. By contacting the shaping portion 49b with the inner peripheral surface of the diameter-expanded portion 31 to adjust the shape, the local diameter-expanded portion 31 and the local diameter-expanded portion 32 are smoothly connected. In this case, since the outer peripheral surface of the can 10 is not pressed during processing, the concave curved surface portion 25 of the enlarged diameter portion 22 formed by the first punch 40A is likely to be formed into a conical surface having a straight vertical cross section. When processing with the second punch 40B, the meat of the can 10 is pressed by the diameter-expanded molding portion 48b, and a clockwise moment acts as shown by the white arrow M in FIGS. The front (lower) portion of the diameter-expanded molding portion 48b is pressed against the outer peripheral surface of the shaping portion 49b to be shaped into a curved surface.

Subsequently, as shown in FIG. 7, the local diameter-expanded portion 33 at a position shifted upward from the local diameter-expanded portion 32 is provided by the third punch 40C, which has a larger processing diameter by the diameter-expanded amount g3 than the second punch 40B. Along with molding, the region from the local diameter expansion portion 31 to the adjacent local diameter expansion portion 32 is shaped, and the local diameter expansion portions 32 to 33 are smoothly connected. Further, as shown in FIG. 8, the local diameter-expanded portion 34 at a position shifted upward from the local diameter-expanded portion 33 is formed by the fourth punch 40D, which has a larger processing diameter by the diameter-expanded amount g4 than the third punch 40C. At the same time, the regions from the local diameter-expanded portions 31 to 33 are shaped to form the diameter-expanded portion 22 to which the local diameter-expanded portions 31 to the local diameter-expanded portions 34 are smoothly connected.

As described above, in the diameter-expanded portion forming step, the diameter-expanded portion 29 is subjected to a plurality of diameter-expanding processes while gradually increasing the processing diameters of the punches 40A to 40D without restraining the outer peripheral surface of the can body 11. Is given. In each diameter expansion step, the amount of diameter expansion processed at one time is reduced without restraining the outer peripheral surface of the can body 11, so that when the punches 40A to 40D enter the inside of the can body 11, The meat of the can body 11 is stretched in the circumferential direction by the punches 40A to 40D and moves outward in the radial direction, while the can body 11 is compressed as the punches 40A to 40D move in the can axis O direction. The meat of the can body 11 is brought toward the lower 23 side in the can axis O direction by receiving a force in the direction of the can body 11, and the diameter is expanded while the height of the can body 11 is gradually reduced. Then, by molding the local diameter-expanding portions 31 to 34 in a plurality of times step by step while shifting the position from the lower side to the upper side, the diameter-expanding amount in which these local diameter-expanding portions 31 to 34 are connected is increased. A large diameter-expanded portion 22 can be formed.

Further, since the amount of diameter expansion at one time in each diameter expansion process is set to 1 mm or less, the wall thickness of the can body 11 is stretched in the circumferential direction as the diameter is increased during each diameter expansion process to reduce the wall thickness. And, the meat of the can body 11 can be brought to the lower 23 side in the can shaft O direction to achieve a balance with the thickening, and in the can shaft O direction corresponding to the processing amount (diameter expansion amount) in the radial direction. It is possible to secure the movement amount (thickness increase amount) of the meat of the can body 11. That is, these thinning and thickening can be offset, and it is possible to prevent the plate thickness of the can body 11 of the processed portion from being reduced and cracks from occurring in the processed portion.

When the diameter expansion amount of the can body 11 to be processed in one diameter expansion process exceeds 1 mm, the meat of the can body 11 is stretched in the circumferential direction to reduce the thickness (thickness reduction amount). As the meat of the can body 11 is brought closer to the lower 23 side in the can axis O direction, the amount of thickening (thickening amount) cannot keep up. That is, the reduction amount of the height (height) of the can body 11 cannot keep up with the processing amount (diameter expansion amount) in the radial direction, and the processed portion of the can body 11 is thinned, so that the processed portion is cracked. It is easy to occur.
By moving the meat of the can body 11 in the can axis direction in each diameter expansion process, the thinning of the can body 11 is suppressed. The height of the can (height of the can body 11) becomes smaller.

Further, in the example of the present embodiment, in the molding portions 42b to 42d of the punches 40B to 40D used for the second and subsequent diameter expansion processing, the front portion of the diameter expansion molding portions 48b to 48d is used for the diameter expansion processing up to that point. Shaping provided in the same shape as the shape in which the molded portions 42a to 42c of the punches 40A to 40C used are connected (that is, the same shape as the portion of the enlarged diameter portion 22 that has been molded by the previous processing). It is formed in a shape including the portions 49b to 49d, and when the new local diameter-expanding portions 32 to 34 are formed by the punches 40B to 40D, the pre-processed local diameter-expanding portions 31 to 33 can be shaped. As a result, the local diameter-expanding portions 32 to 34 processed later can be smoothly connected to the local diameter-expanding portions 31 to 33 processed in the immediately preceding diameter-expanding process. In this way, each time the diameter-expanding process is performed a plurality of times by each of the punches 40A to 40D, the local diameter-expanding portion formed in the previous diameter-expanding process can also be shaped, so that an indentation is formed on the can body 11. It is possible to prevent the cans from being left behind, and it is possible to manufacture a can 20 having a highly cosmetic appearance and having a diameter-expanded portion 22 in which locally enlarged-diameter portions 31 to 34 are smoothly connected.

[Necking process]
Next, the can 20 is subjected to a necking process.
In the present embodiment, a necking die (diameter reduction die) is used to form a neck portion 13 having a smooth inclined shape on the open end portion 11a of the can body 11 by necking. Although not shown, specifically, a necking die (punch and die) is fitted inside and outside the can body 11 of the can 20, and an open end of the can body 11 is provided between the punch and the die. The neck portion 13 is formed by subjecting the portion 11a to a diameter reduction process in which the diameter becomes smaller as it goes upward. Further, by this diameter reduction processing, a cylindrical flange planned portion is formed above the neck portion 13.

In the necking step, instead of the necking process using the necking die described above, the open end portion 11a of the can body 11 may be formed by a spin flow necking process.
The spin flow necking device includes a base pad that sucks and supports the can bottom 12 of the can 20 that has been pre-necked around the open end 11a of the can body 11 by die necking in advance, and the base pad around the can shaft O. A slide roll that is fitted around the open end 11a of the can 20 while rotating to, an internal roll that is inserted inside the can 20 with a diameter smaller than that of the slide roll, and a roll that is arranged outside the can 20 in the radial direction of the can 20. It is provided with a forming roll (external roll) provided so as to be reciprocally movable.
With this spin flow necking device, the can body 11 of the can 20 is sandwiched between the internal roll and the forming roll, the diameter is reduced toward the upper end of the opening end 11a, and the neck portion 13 and the planned flange portion are formed.

[Flanging process]
Next, the planned flange portion located at the open end portion 11a of the can body 11 is flanged to form an annular flange portion 15 that protrudes outward in the radial direction from the upper end of the neck portion 13 and extends along the circumferential direction. Mold.
In the present embodiment, the planned flange portion is flanged by spin flow molding to form the flange portion 15. However, the present invention is not limited to this, and instead of spin flow molding, the flange portion 15 may be formed by flanging the planned flange portion using a mold (punch).

In this way, the can 30 is manufactured and transported to a post-process of the flanging process. In this post-process, the inside of the can 30 is filled with contents such as a beverage, the flange portion 15 is wrapped with a can lid, and the can body is sealed.

According to the method for manufacturing the can 30 according to the present embodiment described above, the local diameter-expanding portions 31 to 34 formed by the molding dies (punch) 40A to 40D by repeating the diameter-expanding processing a plurality of times. Molding is performed while shifting the position from the lower 23 side to the upper 21 side, and these locally expanded diameter portions 31 to 34 are connected to form the enlarged diameter portion 22. Then, without restraining the outer peripheral surface of the can body 11, while gradually increasing the processing diameters of the diameter-expanding dies 40A to 40D, the diameter-expanding dies 40A to 40D having different processing diameters are used in order. Performs diameter expansion processing multiple times. In this way, the diameter-expanding dies 40A to 40D having a reduced diameter-expanding amount g1 to g4 (processing amount) at one time are allowed to enter the inside of the can body 11 without restraining the outer peripheral surface of the can body 11. As a result, as the diameter-expanding dies 40A to 40D move, the meat of the can body 11 moves outward in the radial direction (diameter expansion direction) and is stretched in the circumferential direction, thereby reducing the wall thickness and the can. It is possible to achieve a balance with thickening by moving the meat of the body 11 to the lower side in the can axis O direction, and the thickness of the can body 11 in the processed portion is reduced with each diameter expansion process. It can be suppressed. Then, the local diameter-expanding portions 31 to 34 can be formed stepwise by a plurality of diameter-expanding processes, and the diameter-expanding portion 22 connecting these local diameter-expanding portions 31 to 34 can be formed. As described above, according to the can manufacturing method according to the present embodiment, it is possible to avoid damage such as wrinkles and cracks in the processed portion, and by repeating the diameter expansion processing, the diameter expansion portion 22 having a large diameter expansion amount 22. Can be stably molded. Therefore, it is possible to form a diameter-expanded portion having various shapes such as a diameter-expanded portion that is greatly inclined and a diameter-expanded portion that is inclined over a wide range.

The amount of diameter expansion of the can body processed in one diameter expansion process is preferably 1 mm or less, preferably 0.3 mm or more. When the amount of diameter expansion exceeds 1 mm, the meat of the can body is stretched in the circumferential direction to reduce the thickness (thickness reduction amount), whereas the meat of the can body is moved to the lower side in the can axis direction. The amount of thickening (thickening amount) cannot keep up with the gathering. That is, the amount of reduction in the height (height) of the can body cannot keep up with the amount of processing in the radial direction (diameter expansion amount), and the processed portion of the can body is extended and thinned, so that the processed portion is cracked. It is easy to occur. On the other hand, by setting the diameter expansion amount at one time to 1 mm or less, it is possible to secure the amount of movement (thickening amount) of the meat in the can body in the can axis direction corresponding to the processing amount in the radial direction. It is possible to balance the thinning by stretching the meat in the circumferential direction and the thickening by moving the meat of the can body to the lower side in the can axis direction, and the plate of the can body of the processed part. It is possible to prevent the thickness from being reduced and cracks from occurring in the processed portion. Therefore, a large diameter-expanded portion having a large outer diameter difference of 2% or more and 18% or less with respect to the outer diameter of the lower portion can be stably formed. If the amount of diameter expansion at one time is less than 0.3 mm, springback is likely to occur, so it is desirable to set the amount of diameter expansion to 0.3 mm or more.

Further, in the can manufacturing method according to the present invention, as described above, the diameter-expanded portion 22 can be molded only by the diameter-expanding process without the diameter-reducing process, so that the process can be simplified. Further, in the method for manufacturing a can according to the present invention, the meat of the can body 11 is moved toward the lower side in the can axis O direction to increase the diameter while reducing (shrinking) the height of the can body 11. As a result, it is possible to suppress the thinning of the can body due to the diameter-expanding process, so that it is possible to process a can or the like in which the wall thickness of the can body is partially thickened. Further, since the lower portion 23 of the can body 11 is not subjected to the diameter expansion processing, the plate thickness of the lower portion 23 (lower wall thickness) of the wall thickness of the can body 11 is thinner than the planned diameter expansion portion 29 and the upper portion 28. It can also be provided in a modified form.

The present invention is not limited to the configuration of the above embodiment, and various changes can be made to the detailed configuration without departing from the spirit of the present invention.
For example, in the above-described embodiment, the can 10 on which the enlarged diameter portion 22 is formed is used for a two-piece can (can body) in which a can lid is wrapped around the open end portion 11a, but the can body is limited to this. However, the can 10 may be used for a bottle can (can body) in which a cap is screwed to the open end portion 11a thereof.

(Second Embodiment)
FIG. 10 is a semi-cross-sectional view similar to FIG. 1 showing a can manufactured in the can manufacturing method according to the second embodiment of the present invention. Similar to FIG. 1, the can 201 shown by the solid line is the can before the necking step through the diameter-expanded portion forming step, and the can 301 shown by the alternate long and short dash line is after the opening step 11a of the can 201 is subjected to the necking step and the franging step. Can. Hereinafter, in the second embodiment and the third embodiment, the same reference numerals are given to the common parts with those of the first embodiment to simplify the description.
As shown in FIG. 1, in the can body 111 of the can 20 manufactured by the manufacturing method of the first embodiment, the diameter-expanded portion 22 has a concave curved surface portion 25 at the lower end portion (near the connection portion with the lower portion 23). Most of the enlarged diameter portion 22 is formed by the convex curved surface portion 24. On the other hand, in the can 201 manufactured in the second embodiment, as shown in FIG. 10, the upper end portion (near the connection portion with the upper portion 21) of the enlarged diameter portion 22 is formed in the convex curved portion 24. However, most of the enlarged diameter portion 22 is formed by the concave curved surface portion 25. Further, the enlarged diameter portion 22 is formed longer than the can 20 of the first embodiment.

In this second embodiment, as shown in FIG. 11, as the diameter-expanding portion 22 is long, it is illustrated as a die for diameter-expanding by forming with five punches from the first punch 400A to the fifth punch 401E. There is. These punches 401A to 401E do not have an engaging shaft portion 41 unlike those of the first embodiment.
In the first punch 401A for forming the first locally enlarged diameter portion 31, the enlarged diameter molded portion 48a is formed on a convex surface. The diameter-expanded molded portion 48a is formed in a range of a slight length, and its tip is a flank 44. The upper part of the local diameter-expanded portion 31 is enlarged by the diameter-expanded molding portion 48a of the first punch 401A, and the first punch 401A is not in contact with the lower portion, but the upper portion is expanded by the diameter-expanded molding portion 48a. From the bottom to the bottom, a smooth concave surface is formed as a whole. Next, the second punch 401B that forms the local diameter-expanding portion 32 that is continuous with the local diameter-expanding portion 31 has a long diameter-expanding molding portion 48b that is continuous with the diameter-expanding molding portion 48a of the first punch 401A. The locally enlarged diameter portion 32 is formed in a long range. The molding surface of the diameter-expanded molding portion 48b is formed in a concave shape in which the diameter is gradually increased toward the upward direction corresponding to the local diameter-expanding portion 32.

Next, the third punch 401C for forming the local diameter-expanding portion 33 continuous with the local diameter-expanding portion 32 has a diameter-expanding molding portion 48c on the upper portion thereof so as to be continuous with the diameter-expanding molding portion 48b of the second punch 401B. Is formed, and a shaping portion 49c for shaping the locally enlarged diameter portion 32 formed by the second punch 401B is provided at the lower portion. The molding surface of the diameter-expanded molding portion 48c is formed in a concave shape that gradually expands in diameter in accordance with the local diameter-expanding portion 33, and the shaping surface of the shaping portion 49b is the diameter-expanding molding portion of the second punch 401B. It is formed in the same shape as the molding surface of 48b.
Hereinafter, the 4th punch 401D and the 5th punch 401E have the same configuration as the 3rd punch 401C, and the local diameter expansion portions 34, 35 continuous with the local diameter expansion portion 33 are sequentially formed by the diameter expansion molding portions 48d, 48e. While forming, the previously formed local diameter-expanded portions 33 and 34 are shaped by the shaping portions 49d and 49e to form the entire diameter-expanded portion 22.

(Third Embodiment)
FIG. 12 is a semi-cross-sectional view similar to FIG. 1 showing a can manufactured in the can manufacturing method according to the third embodiment of the present invention. The can 202 shown by the solid line is the can before the necking process that has undergone the enlarged diameter forming step, and the can 302 shown by the alternate long and short dash line is the can after the opening step 11a of the can 202 is subjected to the necking step and the franging step. Is the same as in FIGS. 1 and 10.
As shown in FIG. 12, the can body 112 of the can 202 manufactured in the third embodiment has a convex curved surface because the upper end portion (near the connection portion with the upper portion 21) of the enlarged diameter portion 22 is connected to the upper portion 21. The lower end of the enlarged diameter portion 22 (near the connection portion with the lower portion 23) is formed on the concave curved surface portion 25 for connection with the lower portion 23, and the enlarged diameter portion 22 between them is formed. Most of them are formed on the tapered surface portion 26 having a linear vertical cross section along the can axis direction.

In the third embodiment as well, as in the second embodiment, the diameter-expanding portion 22 is formed by five punches from the first punch 402A to the fifth punch 402E as the diameter-expanding die. The point that these punches 402A to 402E do not have the engaging shaft portion 41 is also the same as in the second embodiment.
Further, in the first punch 402A for forming the first locally enlarged diameter portion 31, the enlarged diameter molded portion 48a is formed in a convex surface within a range of a slight length, and the tip thereof is a flank surface 44. The upper part of the local diameter-expanded portion 31 is enlarged by the diameter-expanded molding portion 48a of the first punch 402A, and the first punch 402A is not in contact with the lower portion, but the upper portion is expanded by the diameter-expanded molding portion 48a. The concave curved surface portion 25 is formed from the lower part to the lower part. Next, the second punch 402B that forms the local diameter-expanding portion 32 that is continuous with the local diameter-expanding portion 31 has a long diameter-expanding molding portion 48b that is continuous with the diameter-expanding molding portion 48a of the first punch 402A. The locally enlarged diameter portion 32 is formed in a long range. The molding surface of the diameter-expanded molding portion 48b is formed in a tapered surface shape in which the diameter gradually increases toward the upward direction corresponding to the local diameter-expanding portion 32.

Then, the third punch 402C that forms the local diameter-expanding portion 33 that is continuous with the local diameter-expanding portion 32 has a diameter-expanding molding portion 48c on the upper portion thereof so as to be continuous with the diameter-expanding molding portion 48b of the second punch 402B. Is formed, and a shaping portion 49c for shaping the locally enlarged diameter portion 32 formed by the second punch 402B is provided at the lower portion. The molding surface of the diameter-expanded molding portion 48c is formed in a tapered surface shape in which the diameter gradually increases upward in response to the local diameter-expanding portion 33, and the shaping surface of the shaping portion 49b is the diameter-expanding molding of the second punch 402B. It is formed in the same shape as the molding surface of the portion 48b.
Hereinafter, the fourth punch 402D and the fifth punch 402E have the same configuration as the third punch 402C, and the local diameter-expanding portions 34, 35 continuous with the local diameter-expanding portion 33 are sequentially formed by the diameter-expanding molding portions 48d, 48e. While forming, the previously formed local diameter-expanded portions 33 and 34 are shaped by the shaping portions 49d and 49e to form the entire diameter-expanded portion 22.

In addition, each configuration (component) described in the above-described embodiments, modifications, and notes may be combined as long as it does not deviate from the gist of the present invention. It can be changed. Further, the present invention is not limited by the above-described embodiments, but is limited only by the scope of claims.

Next, an experiment was conducted to confirm the effect of the can manufacturing method of the present embodiment.
As shown in FIG. 4, a plate material made of an aluminum alloy material (3104 series aluminum alloy) having a plate thickness of 0.475 mm is processed, the height (height) in the can axis O direction is 157 mm, and the outer diameter D0 of the can body 11 is formed. Is 57 mm, the upper wall thickness between the lower end of the planned expansion portion 29 of the can body 11 and the opening end portion 11a (the planned expansion portion 29 and the upper 28) is 0.23 mm, and the lower wall thickness of the lower 23 is 0. A bottomed cylindrical can 10 having a size of 16 mm is formed, and the can 10 is subjected to a diameter-expanded portion forming step under the conditions shown in Table 1, and has a diameter-expanded portion 22 as shown in FIG. Can 20 was manufactured. Further, under each condition shown in Table 1, 50 cans 20 were produced. Then, with respect to the manufactured can 20, the difference in outer diameter between the lower 23 and the upper 21 of the can body 11, the height of the can (height), and the plate thickness of the can body (upper wall thickness) are measured, and the moldability is determined. Confirmed. In the evaluation of "moldability", the appearance of 50 cans 20 made under each condition was observed, and when one or more cans had cracks (cracks), "x" was observed and no cracks occurred in one can. The case was marked as "○".
The results are shown in Table 1.

As can be seen from the results in Table 1, by performing the diameter expansion process multiple times with the diameter expansion amount set to 1 mm or less, the diameter expansion ratio (outer diameter difference) between the lower part and the upper part of the can body is not damaged. ) To the lower outer diameter Db in the range of 2% or more and 18% or less, and cans in which enlarged diameter portions of various sizes are formed can be manufactured.
In Comparative Example 1 in which the overall diameter expansion rate exceeds 18% and Comparative Example 2 in which the diameter expansion amount at one time exceeds 1 mm, cracks occur in the processed portion.

10, 20, 30, 201, 202, 301, 302 Can 11,111,112 Can body 11a Open end 12 Can bottom 13 Neck 15 Flange 19 Ear 21 Upper 22 Diameter 23 Lower 24 Convex curved surface 25 Concave Curved surface part 26 Tapered surface part 28 Upper part 29 Diameter expansion planned part 31, 32, 33, 34, 35 Local diameter expansion part 40A, 401A, 402A 1st punch (diameter for diameter expansion)
40B, 401B, 402B 2nd punch (diameter expansion die)
40C, 401C, 402C 3rd punch (diameter expansion die)
40D, 401D, 402D 4th punch (diameter expansion die)
401E, 402E 5th punch (diameter expansion die)
41 Engagement shaft portion 42a, 42b, 42c, 42d Molding portion 43a Straight molding portion 44 Tip relief portion 45 Base end relief portion 46a, 46b, 46c R surface 48a, 48b, 48c, 48d, 48e Enlarged diameter molding portions 49b, 49c , 49d, 49e Orthopedic section

Claims (4)

Manufacture of a bottomed cylindrical can having a can body and a can bottom and having an outer diameter difference between the lower part of the can body and the upper part of the can body being 2% or more and 18% or less with respect to the outer diameter of the lower part. It ’s a method,
From the lower side to the upper side of the can body along the can axis direction, the diameter-expanded portion provided between the lower part of the can body arranged on the can bottom side and the upper part arranged on the opening end side. It is equipped with a diameter-expanded portion molding process that forms a diameter-expanded portion that gradually increases in diameter toward
The diameter-expanded portion molding step is
By entering the diameter-expanding die into the inside of the can body and moving it relative to the can axis direction, the diameter-expanding process for expanding the entire region from the opening end portion of the can body to the planned diameter-expanding portion is performed. The processing diameter of the diameter-expanding mold is increased stepwise with an expansion amount of 1.0 mm or less, and the diameter is divided into a plurality of times.
A method for manufacturing a can, characterized in that each time the diameter-expanding process is performed, the locally-diameter-expanded portion formed by each diameter-expanding die is molded while shifting the position from the lower side to the upper side. .. The diameter-expanded portion molding step is
The method for manufacturing a can according to claim 1, wherein the height of the can body in the can axial direction is gradually reduced in each of the plurality of diameter expansion processes. In the diameter-expanded portion molding step
1. 2. The method for manufacturing a can according to 2. In the diameter-expanded portion molding step
An engaging shaft portion that engages with the inner peripheral surface of the lower portion of the can body is provided at the tip end portion of the diameter expansion mold.
The invention according to any one of claims 1 to 3 , wherein the engaging shaft portion is inserted into the lower part of the can body to align the diameter-expanding die and the can body. How to make cans.

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