JP2022120828A - Manufacturing method of metallic cup - Google Patents

Abstract

To manufacture a metallic cup which prevents wrinkle and cracks on an outer peripheral surface and has a smooth tapered body section.SOLUTION: A method of manufacturing a metallic cup by press-molding a metal plate includes a drawing-and-squeezing process of forming a bottomed cylindrical cylinder body by drawing and squeezing the metal plate, and a diameter-enlarging process of forming an intermediate cylinder body having a tapered cylinder section by gradually enlarging a diameter of a body section of the cylinder body from a bottom part side to an opening end part side by pressing a punch into the cylinder body from the opening end part side after the drawing-and-squeezing process.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a metal cup made of aluminum alloy or the like.

Existing drinking cups are made of ceramic, glass, metal, paper, plastic, and the like. Of these, cups made of metal, paper, and plastic are lighter and less bulky when stacked than those made of ceramics or glass, so they are excellent in portability.

Patent Literature 1 discloses a tapered metal cup (metal cup). The metal cup is made of aluminum and is said to be harder, more durable and more recyclable than plastic cups.

As a method of manufacturing this metal cup, a metal plate is punched and drawn to form a cup, and the cup is subjected to ironing to form a cylindrical vertical wall preform (DI process). After trimming the open end to set the height, the open end is rolled to form a curl, and further stepwise drawing is performed to continuously reduce the diameter and height from the curl to the bottom. Forming a vertical drawn cup with vertical wall sections and then widening each of the vertical wall sections using a die having a tapered profile to form a tapered cup with tapered sidewalls for each vertical wall section. and finally forming a domed portion at the bottom of the cup.

JP 2020-508874 A

As in Patent Document 1, when a metal plate is drawn to produce a metal cup that is taller than its diameter, if the barrel is tapered, wrinkles and cracks are likely to occur on the outer peripheral surface. . In Patent Literature 1, the body portion is formed with a stepwise tapered side wall by a plurality of sections, but it is desirable to form the body portion into a smooth tapered shape from the bottom of the cup to the open end.

The present invention has been made in view of such circumstances, and provides a method for manufacturing a metal cup that is less prone to wrinkles and cracks on the outer peripheral surface and has a smoothly tapered barrel. intended to provide

The present invention is a method for producing a metal cup by press forming a metal plate, comprising a drawing and ironing step of forming a bottomed cylindrical cylindrical body by drawing and ironing the metal plate, and after the drawing and ironing step a punch is pushed into the cylindrical body from the opening end side to gradually expand the diameter of the trunk portion of the cylindrical body from the bottom side toward the opening end side to form an intermediate cylindrical body having a tapered cylindrical portion. and a diameter-expanding step.

In the manufacturing method described in Patent Document 1, after forming a cylindrical body with a bottom, drawing is performed so as to gradually reduce the diameter from the open end of the cylindrical body toward the bottom. In the present invention, the cylindrical body is formed so that its diameter gradually increases from the bottom toward the open end. In other words, while the processing described in Patent Document 1 is processing that presses the metal material radially inward from the outer peripheral side, in the present invention, the metal material is expanded radially outward from the inner peripheral side. Therefore, it is possible to form a smooth tapered body portion that is less prone to wrinkles.

The drawing and ironing process for forming a bottomed cylindrical cylinder can apply the same technique as that for existing beverage cans. In this case, the existing manufacturing equipment forms a cylindrical body with a diameter of about 66 mm, which is a size that is easy to hold.

If the cylindrical body obtained by the drawing and ironing process of the existing equipment is formed into a metal cup by the method described in Patent Document 1, the final shape cup will have a small diameter because it is a process of drawing from the cylindrical body. , it is necessary to make a long and narrow cup to have the same capacity as the existing cylinder. In particular, since the bottom has the smallest diameter, there is a risk that it will fall over when placed on a table or the like. On the other hand, if an attempt is made to manufacture a cup with a large diameter, it is necessary to change the drawing and ironing process equipment on a large scale to one capable of forming a cylindrical body with a large diameter.

In the manufacturing method of the present invention, since the cylindrical body is expanded, the capacity can be adjusted by height. It is economical because the equipment for manufacturing beverage cans can be used as it is.

In the method for manufacturing a metal cup of the present invention, one or more punches are used to increase the diameter of the body of the cylindrical body to the opening end side from the diameter of the bottom side of the cylindrical body. and a step forming step of forming a step portion having a large diameter, and a shaping step of shaping the step portion into the tapered tubular portion while expanding the step portion using one or more punches.

When forming a tapered cylindrical portion in the trunk portion of a bottomed cylindrical cylindrical body, if the taper angle is large, cracks are likely to occur if the tapered punch is used from the beginning. For this reason, in the present invention, first, in the stepped portion forming step, a stepped portion having a larger diameter on the opening end side than the diameter on the bottom side is formed, and the tapered cylindrical portion is formed while expanding the stepped portion. Cracks are less likely to occur, and as a result, a smooth tapered surface can be formed.

In this case, the step forming step and the shaping step can be alternately performed a plurality of times.

Alternatively, after forming a plurality of stepped portions in the stepped portion forming step, the shaping step may be performed on each of these stepped portions, or a plurality of stepped portions may be performed collectively.

In the metal cup manufacturing method of the present invention, the punch used in the step forming step comprises a stepped punch in which a guide portion having a cylindrical outer surface and a forming portion having a larger diameter than the guide portion are connected. Alternatively, by inserting the guide portion of the stepped punch first into the cylindrical body, the diameter of the cylindrical body is expanded by the forming portion while the guide portion is fitted into the cylindrical body. good.

Since the guide portion of the stepped punch is inserted into the cylindrical body first, the cylindrical body and the stepped punch are aligned with each other. can produce high cups.

In this case, a lower stepped portion is further formed near the bottom of the body of the metal cup, and the punch used in the stepped portion forming step has a lower stepped portion having a forming portion having a cylindrical outer surface. After forming an initial stepped portion near the bottom portion of the body portion with the stepped punch, the lower portion of the initial stepped portion is formed by fitting the lower stepped portion punch into the initial stepped portion. It is preferable to form the lower stepped portion by processing while increasing the diameter of the .

Since the lower stepped portion is formed on the bottommost side of the cylindrical body, if a stepped punch having a guide portion is used for molding, the guide portion may come into contact with the inner bottom surface of the cylindrical body. For this reason, first, an initial stepped portion is formed by a stepped punch at a position above the formation position of the lower stepped portion, and the position of the initial stepped portion is pressed downward by a lower stepped portion punch. Since the punch for the lower stepped portion can have a structure that does not have a guide portion, the bottom portion will not be deformed even if the lower stepped portion is formed by bringing the punch closer to the bottom portion.

The method for manufacturing a metal cup according to the present invention preferably includes a curling step of folding back the open end portion of the intermediate cylinder to form a curled portion after the diameter expanding step. Since the opening end has a curled portion, the mouthfeel is improved when the lips are shaken.

In this case, it is preferable to form a straight upper cylindrical portion along the can axial direction at the open end portion of the intermediate cylindrical body by performing the stepped portion forming step in the diameter expanding step. In the curling process, the molding tool is pressed from the open end of the intermediate cylinder in the can axial direction, so the load can be received by the straight upper cylindrical part, and the curled part can be formed with high accuracy.

In other words, if the shape gradually increasing in diameter from the bottom to the open end is continued, deformation in the curl forming process is large, and it is difficult to form the shape accurately. Therefore, by forming a cylindrical portion at the open end to increase the deformation strength thereof, the curled portion can be formed more accurately without being deformed in the curl forming process.

Further, the upper cylindrical portion is preferably formed by a punch for upper step portion. This is because the tapered portion formed in the previous step may be deformed by the guide portion if a stepped punch is used since this is the last step in the diameter-enlarging step.

According to the present invention, it is possible to manufacture a metal cup having a smoothly tapered trunk portion in which wrinkles and cracks are less likely to occur on the outer peripheral surface.

1 is a front view of a metal cup manufactured by a manufacturing method according to an embodiment of the present invention, with half of the cup centered on the can axis as a vertical cross section; FIG. It is the front view which made half the vertical cross section centering on the can axis|shaft of the cylinder obtained by the drawing ironing process. FIG. 10 is a vertical cross-sectional view of a main part showing a state being processed in a step of forming a lower stepped portion; FIG. 4 is a vertical cross-sectional view of a main part showing a state of being processed in a stepped portion forming step; FIG. 5 is a vertical cross-sectional view of a main part showing a state of processing in a shaping step following the stepped portion forming step in FIG. 4 ; FIG. 6 is a vertical cross-sectional view of a main part showing a state of processing in a stepped portion forming step following the shaping step in FIG. 5 ; FIG. 4 is a cross-sectional view showing a state of processing with a curling tool in a curling process;

Hereinafter, an embodiment of a method for manufacturing a metal cup according to the present invention will be described with reference to the drawings.

The metal cup 1 manufactured by the manufacturing method of the present embodiment is, as shown in FIG. The diameter of the open end 3 is larger than that of the open end 3, and the body 4 has a tapered body portion 4 whose diameter gradually increases from the bottom 2 toward the open end 3 as a whole. A curled portion 5 is formed in the open end portion 3 by winding the end portion including the edge portion radially outward. Let the can axis C be the center of the metal cup 1 in the radial direction.

The bottom portion 2 includes a concavely curved dome portion 6, an inner tapered wall portion 7 continuous with the outer peripheral edge of the dome portion 6, an inner tapered wall portion 7 gradually increasing in diameter downward in the can axial direction, and an outer peripheral edge of the inner tapered wall portion 7. A rim portion 8 that touches the ground when the cup 1 is placed on a table or the like, and a tapered rising portion 9 that extends from the outer peripheral end of the rim portion 8 to the bottom end of the body portion 4 are continuous.

The dome portion 6 has a concave shape where the distance from the tip of the rim portion 8 is the greatest at the position on the can axis C. As shown in FIG. The rim portion 8 is formed in a ring shape around the can axis C, is formed on a curved surface that is convex toward the lower side of the can axis C, and is grounded at the most protruding position. The outermost edge of the rim portion 8 is smaller in diameter than the lowermost edge of the body portion 4, which has the smallest diameter. Concatenated.

The trunk portion 4 has a straight lower cylindrical portion 11 and an upper cylindrical portion 12 along the can axis C near the bottom portion 2 and near the open end portion 3 . A lower stepped portion 13 is formed in a small range on the upper end of the lower cylindrical portion 11 that is continuous from the bottom portion 2, and an upper stepped portion 14 is also formed in a small range on the lower end of the upper cylindrical portion 12 that is continuous with the curled portion 5. is formed. Between the upper end of the lower stepped portion 13 and the lower end of the upper stepped portion 14 is formed a tapered tubular portion 15 whose diameter gradually increases from the bottom to the top.

Although these dimensions are not necessarily limited, they are set as follows, for example.
Curl portion diameter (outer diameter) D1: 75 mm or more and 100 mm or less Ground contact portion diameter D2: 45 mm or more and 60 mm or less Overall height H1: 80 mm or more and 180 mm or less Depth H2 of dome portion 6: 1 mm or more and 15 mm or less Lower cylindrical portion 11 diameter D3: 50 mm or more and 70 mm or less Diameter D4 of the upper cylindrical portion 12: 70 mm or more and 95 mm or less Height H3 from the bottom surface to the lower end of the lower step portion 13: 8 mm or more and 25 mm or less From the upper end of the curled portion 5 to the upper end of the upper step portion 14 length H4: 8 mm or more and 20 mm or less Angle θ of the tapered cylindrical portion 15 with respect to the horizontal plane: 80° or more and 85° or less

Next, a method for manufacturing the metal cup 1 will be described. In the metal cup 1, a plurality of punches 40 to 43 having different outer diameters are removed in a cylindrical body forming step of forming a bottomed cylindrical cylindrical body 21 by drawing and ironing a metal plate, and after the cylindrical body forming step. The punches 40 to 43 are pushed into the cylindrical body 21 from the open end 22 side while being used in ascending order of diameter, and the body 23 of the cylindrical body 21 is gradually moved from the bottom 2 side toward the open end 22 side. A diameter-expanding step of forming the tapered tubular portion 15 to form the intermediate tubular body 50, and a curling step of forming the curled portion 5 at the open end of the intermediate tubular body 50 formed by this diameter-expanding step. , is manufactured through a process having The order of steps will be described below.

[Cylinder Forming Step]
In the cylindrical body forming step, a cup 25 having a larger diameter and shallower diameter than the cylindrical body 21 in the next step is formed by punching and drawing a plate material made of aluminum or an aluminum alloy (FIG. 2(a)). Then, the cup 25 is drawn and ironed (drawn and ironed) to form a cylindrical body 21 having a smaller diameter than the cup 25 and a predetermined height with a bottom as shown in the drawing (Fig. 2). (b)).

In this drawing and ironing process, the bottom portion 2 of the cylindrical body 21 is finished in the final shape of the bottom portion 2 of the metal cup 1, and has a dome portion 6, an inner tapered wall portion 7, a rim portion 8, and a tapered rising portion 9. is doing.

[Diameter expansion process]
The diameter-expanding step consists of a plurality of steps, a stepped portion forming step of forming a stepped portion having a larger diameter on the side of the opening end portion 22 than the diameter on the side of the bottom portion 2, and a stepped portion expanding step. By sequentially repeating the shaping step of shaping into a tapered surface, the intermediate cylindrical body 50 shown in FIG. 2(c) is formed.

In this case, after the lower step portion forming step of forming the lower step portion 13 at the lowermost portion of the cylindrical body 21, the first step portion forming step of forming the first step portion slightly above the lower step portion 13; A first shaping step of shaping the first stepped portion, a second stepped portion forming step of forming the second stepped portion near the upper end of the shaping surface, a second shaping step of shaping the second stepped portion, and so on. After forming the first lower stepped portion, the stepped portion forming step and the shaping step are alternately carried out to form one stepped portion, and the stepped portion is shaped to form a tapered shape as a whole. For example, the step forming process and the shaping process are alternately performed 10 to 30 times.

Finally, at the uppermost part of the cylindrical body 21, an upper stepped portion forming step for forming the upper stepped portion 14 is performed, thereby completing the diameter expanding step.

The details are described below. In this diameter-enlarging step, the shape of the cylindrical body 21 gradually changes. The cylindrical body used in the cylindrical body forming step will be described with the same reference numeral 21 as that used in the cylindrical body forming step.

(Stepped portion forming step)
As shown in FIGS. 3 to 6, the stepped portion forming step uses a plurality of stepped punches 40 to 42 having different diameters, two lower stepped punches 43 and an upper stepped punch (FIGS. 3 to 6). 1 shows only three stepped punches 40 to 42 with different diameters and one lower stepped punch 43. The upper stepped punch has a different diameter but has the same outer shape as the lower stepped punch. Therefore, description will be made with reference to the lower step portion punch 43 as necessary).

The stepped punches 40 to 42, as shown in FIGS. 4 and 6 (indicated by two-dot chain lines in FIGS. 3 and 5 as well), have a guide portion 44 and a forming portion 45 having a larger diameter than the guide portion 44. , and the guide portion 44 is arranged on the distal end side. The guide portion 44 is inserted into the cylindrical body 21 first, but the guide portion 44 is used for alignment with the cylindrical body 21 without molding the cylindrical body 21 .

The outer peripheral surface of the guide portion 44 of these stepped punches 40 to 42 is formed with a round chamfered surface 46 on the tip end side, and a substantially straight cylindrical outer surface 47 is formed from the outer peripheral end of the rounded chamfered surface 46 . The maximum diameter of the guide portion 44 of each of the stepped punches 40-42 is slightly smaller than the inner diameter of the opening of the cylindrical body 21 before the stepped portion is formed by the stepped punches 40-42.

The molding portion 45 is formed on a convex curved surface so as to protrude radially outward from the cylindrical outer surface 47 of the guide portion 44 , and has a maximum diameter larger than the diameter of the cylindrical outer surface 47 of the guide portion 44 . there is Stepped portions 51 to 53 (in FIGS. 3 to 6, stepped portions having different molded portions are denoted by reference numerals 51 to 53, respectively). ) are formed.

As shown in FIG. 3, the lower stepped punch 43 does not have a guide portion 44 like the stepped punches 40 to 42. The surface of the forming portion 48 is extended to the tip, and the corners of the tip periphery are formed into convex arcs. It is a punch with a chamfered shape. In FIG. 3, the lower step portion punch 43 is formed in a stepless shape. Although the diameter of the punch for the upper step portion is also different, the punch for the lower step portion does not have the guide portion 44 like the punches with steps 40 to 42, and the surface of the forming portion (see reference numeral 48) is extended to the tip. It has a curved shape.

The lower stepped punch 43 is formed to have a diameter equal to or slightly smaller than that of the forming portion 45 of the stepped punch 40, which has the smallest diameter among the stepped punches 40 to 42, and the upper stepped punch has a shaping portion. It is formed to have a diameter equal to or slightly smaller than the maximum diameter of the shaping surface 65 of the shaping punch 61 having the largest diameter among the shaping punches 61 used in the process (although illustration of the punch for the upper step portion is omitted). , and the punch 43 for the lower step portion is representatively shown for its shape, so refer to this).

Since the punch 43 for the lower stepped portion and the punch for the upper stepped portion do not have the guide portion 44, the convex curved surface 48a of the molding portion 48 is formed to extend in the distal direction, and the minimum diameter thereof is The inner diameters are smaller than the inner diameters of the cylindrical body before being formed by the lower stepped punch 43 and the upper stepped punch.

(Shaping process)
In the shaping step, the stepped portions 52 and 53 formed in the stepped portion forming step are shaped into smooth tapered surfaces. As shown in FIG. 5, a shaping punch 61 used in this shaping process has a tip end formed with a rounded chamfered surface 62 and a rear end of the rounded chamfered surface 62 with a taper that gradually widens from the tip toward the rear. A convex curved surface 64 with a large radius of curvature is formed on the rear end surface of the tapered surface 63 . A shaping surface 65 is defined as a region extending from the middle position of the tapered surface 63 to the front half of the convex curved surface 64 .

In this case, the shaping surface 65 is formed long in the distal direction so that shaping can be performed from a position sufficiently distant in the distal direction from the stepped portion 52 formed in the stepped portion forming step, as indicated by reference numeral 65a. On the other hand, the rear end 65b of the shaping surface 65 is formed to have a length that allows shaping up to a slightly rearward position of the stepped portions 52 and 53 formed in the stepped portion forming step.

Therefore, the shaping surface 65 is not a straight tapered surface, but a tapered surface having a convex curved surface 64 that bulges slightly outward in the radial direction. With such a shape, it is possible to suppress elastic recovery (springback) when a wide area including the front and rear of the stepped portions 52 and 53 is pushed outward in the radial direction, and the trunk portion 23 of the cylindrical body 21 can be suppressed. can be reliably formed on the tapered surface. Therefore, in this shaping step, wide regions in front of and behind the stepped portions 52 and 53 formed in the stepped portion forming step can be shaped into a smooth tapered shape.

In the steps of forming the stepped portion and the shaping step, first, the lower stepped portion 13 located at the lowest position of the body portion 4 is formed (FIG. 3, step of forming the lower stepped portion). The lower stepped portion 13 is formed by a stepped punch 40 having the smallest diameter and a lower stepped portion punch 43. First, the stepped punch 40 forms a stepped portion near the bottom portion 2 (the initial stepped portion at this time). ) 51 is formed.

In this case, the processing is performed at a position near the bottom surface of the cylindrical body 21, and if the stepped punch 40 is used to process a position close to the bottom portion 2, there is a risk that the guide portion 44 will collide with the previously processed bottom portion 2 and deform it. Therefore, the stepped punch 40 is processed to a position where the bottom 2 is not reached. The state of processing by the stepped punch 40 is indicated by a chain double-dashed line in FIG.

Next, the punch 43 for the lower stepped portion is fitted to the cylindrical body 21, and the initial stepped portion 51 formed by the stepped punch 40 is pushed downward while expanding the diameter of the lower portion of the initial stepped portion 51. It is processed to form the lower step portion 13 . Since the punch 43 for the lower step portion is formed to have the same or slightly smaller outer diameter than the forming portion 45 of the stepped punch 40 , it fits into the body portion 23 of the cylindrical body 21 expanded in diameter by the step portion 52 . and aligned with the trunk 23 . In addition, since the lower stepped punch 43 does not have the guide portion 44, it can be brought closer to the bottom 2 than the stepped punch 40.例文帳に追加

The position below the lower stepped portion 13 formed by the lower stepped portion forming punch 43 is a portion where the outer peripheral surface of the cylindrical body 21 is held by the chuck portion 70 during the diameter expanding process including the step of forming the lower stepped portion. The lower cylindrical portion 11 is left straight without being tapered.

Next, a first stepped portion 52 is formed slightly above the lower stepped portion 13 (not shown in FIG. 4) by a stepped punch 41 having the second smallest diameter (explained with reference to FIG. 4 for convenience). . At this time, the guide portion 44 of the stepped punch 41 is inserted into the large-diameter portion of the lower stepped portion 13 to align the punch 41 with the cylindrical body 21 .

After forming the first stepped portion 52, the front and rear portions of the first stepped portion 52 are shaped into a smooth tapered shape by a shaping punch 61 (FIG. 5). In this case, as described above, the shaping surface 65 of the shaping punch 61 is formed not as a straight tapered surface but as a curved surface that bulges slightly outward in the radial direction. can be sufficiently expanded from the radially inner side to effectively erase the traces thereof, and can be formed into a smooth tapered shape.

After repeating the steps of forming the stepped portion and the shaping step a required number of times, finally, the upper stepped portion 14 is formed at a position slightly below the open end portion 22 of the cylindrical body 21 by an upper stepped portion punch (not shown). (upper step forming step). Like the lower stepped punch 43, this upper stepped punch also has only a forming portion 48 without a guide portion.

Since this upper step forming punch is formed to have the same diameter as or slightly smaller than the shaping surface 65 of the shaping punch 61 having the largest diameter, it can be fitted without resistance from the open end 22 of the previously formed cylindrical body 21 . centered together. Then, the top portion of the tapered surface shaped by the shaping punch 61 is processed to form the upper step portion 14 . Above the upper stepped portion 14 is a straight cylindrical upper cylindrical portion 12' (see the chain double-dashed line in FIG. 7).

After the upper stepped portion 14 is formed, the upper cylindrical portion 12' is left straight, so the shaping step is not performed. Since the tapered portion shaped in the shaping process is deformed by the guide portion 44, a punch (punch for upper step portion) without the guide portion 44 is used so as not to deform the lower portion of the upper step portion 14. I have to.

Therefore, the tapered intermediate cylindrical body 51 formed by this series of diameter-enlarging processes has a straight lower cylindrical portion 11 along the can axis C in the vicinity of the bottom portion 2, and an opening portion 22 that is also a straight upper portion. It is formed on the cylindrical portion 12'.

[Curl process]
After the diameter-expanding step, the curled portion 5 is formed by winding while folding the end portion including the edge of the upper cylindrical portion 12' of the intermediate cylinder 50 radially outward. In this curling process, as shown in FIG. 7, a plurality of curling tools 71 are used.

Each curling tool 71 is rotatable about an axis C1 along a direction crossing the can axis C, and has a forming groove 72 along its circumferential direction. Then, each curling tool 71 is pressed against the open end of the intermediate cylindrical body 50 in the direction of the can axis C and turned around the upper cylindrical portion 12', so that the edge of the upper cylindrical portion 12' is covered by the forming groove 72. The curled portion 5 is formed by folding the ends while expanding them.

In this curling process, the curling tool 71 presses the tapered intermediate cylindrical body 50 in the can axis C direction. In addition, buckling and deformation are less likely to occur due to the effect of work hardening due to the diameter expansion process up to that point.

The metal cup 1 manufactured in this manner has straight cylindrical portions 11 and 12 of some length near the bottom portion 2 and the open end portion 3, and most of the body portion 4 therebetween extends from the bottom portion 2. It is formed in a tapered shape that gradually expands in diameter toward the open end 3 . In the manufacturing method, after forming the stepped portions 52 and 53 having a larger diameter on the side of the open end portion 22 than on the side of the bottom portion 2 of the cylindrical body 21, the stepped portions 52 and 53 are formed into a tapered shape so as to expand. By repeating the steps, the entire body portion 4 is formed into a smooth tapered shape.

In this case, since the metal material is expanded radially outward from the inner peripheral side, wrinkles are less likely to occur. Moreover, since the stepped portions 52 and 53 are first formed and then shaped into a tapered shape, cracks are less likely to occur than when the stepped portions 52 and 53 are not formed and the tapered shape is processed. Therefore, a smooth tapered trunk portion 4 can be formed.

In addition, the bottom 2 of the metal cup 1 uses the bottom 2 formed on the cylindrical body 21 with a bottom formed in the initial stage as it is. there is Therefore, the step of forming the cylindrical body 21 (cylindrical body forming step) can be carried out using the existing facilities for beverage cans as they are.

In addition, since the curled portion 5 is formed in the opening 3, the texture is also smooth.

In the above-described embodiment, in the diameter expanding step, after forming one stepped portion, this stepped portion is shaped into a tapered surface, and then a new stepped portion is formed above it to shape it into a tapered surface. , the stepped portion forming step and the shaping step are alternately repeated, but by performing the stepped portion forming step a plurality of times, a plurality of stepped portions are formed along the can axis C, and then these stepped portions are formed. It is good also as shaping one by one from the bottom part side one by one. It is also possible to collectively shape two or more stepped portions.

In addition, the above embodiments can be modified as appropriate without departing from the scope of the present invention.

C Can Shaft 1 Metal Cup 2 Bottom 3 Open End 4 Body 5 Curl 6 Dome 7 Inner Tapered Wall 8 Rim 9 Rise 11 Lower Cylindrical 12 Upper Cylindrical 13 Lower Step 14 Upper Step 15 Tapered tubular portion 21 tubular body 25 cups 41, 42 stepped punch 43 lower stepped punch 44 guide portion 45 molded portion 47 cylindrical outer surface 48 molded portion 48a convex curved surface 50 intermediate tubular body 51 stepped portion (initial stepped portion)
52, 53 step portion 61 shaping punch 63 tapered surface 64 convex curved surface 65 shaping surface 70 chuck portion 71 curling tool 72 shaping groove

Claims (8)

A method for manufacturing a metal cup by press-molding a metal plate,
A drawing and ironing step of forming a bottomed cylindrical cylinder by drawing and ironing a metal plate;
After the drawing and ironing process, a punch is pushed into the cylindrical body from the opening end side, and the body portion of the cylindrical body is gradually expanded from the bottom side toward the opening end side to form an intermediate portion having a tapered cylindrical portion. a diameter-expanding step of forming a cylindrical body;
A method for manufacturing a metal cup, comprising: The diameter-expanding step includes:
a stepped portion forming step of forming a stepped portion having a larger diameter on the opening end side than the diameter on the bottom side of the cylindrical body in the trunk portion of the cylindrical body using one or more of the punches;
2. The method of manufacturing a metal cup according to claim 1, further comprising a shaping step of shaping the tapered cylindrical portion while spreading the stepped portion using one or more of the punches. 3. The method of manufacturing a metal cup according to claim 2, wherein in the diameter expanding step, the step forming step and the shaping step are alternately performed a plurality of times. 3. The method of manufacturing a metal cup according to claim 2, wherein after forming the plurality of stepped portions in the stepped portion forming step, the stepped portions are subjected to the shaping step. The punch used in the stepped portion forming step comprises a stepped punch in which a guide portion having a cylindrical outer surface and a forming portion having a larger diameter than the guide portion are connected,
By inserting the guide portion of the stepped punch first into the cylindrical body, the diameter of the cylindrical body is expanded by the forming portion while the guide portion is fitted into the cylindrical body. Item 5. A method for manufacturing a metal cup according to any one of Items 2 to 4. A lower stepped portion is further formed near the bottom of the body of the metal cup,
The punch used in the stepped portion forming step further includes a lower stepped portion punch having a forming portion having a cylindrical outer surface,
After forming an initial stepped portion near the bottom portion of the body portion with the stepped punch, the punch for the lower stepped portion is fitted into the initial stepped portion, and the lower portion of the initial stepped portion is processed while expanding the diameter. 6. The method of manufacturing a metal cup according to claim 5, wherein the lower stepped portion is formed by: 7. The metal cup according to any one of claims 1 to 6, further comprising a curling step of folding back the open end portion of the intermediate cylindrical body to form a curled portion after the diameter expanding step. Production method. 8. The metal cup according to claim 7, wherein an upper cylindrical portion is formed along the can axial direction at the open end of the intermediate cylindrical body by performing the stepped portion forming step in the diameter expanding step. manufacturing method.

Images