JP2023069570A - Metallic cup manufacturing method - Google Patents

Abstract

To provide a method of manufacturing a tapered metallic cup having a relatively large diameter while enabling use of an existing facility.SOLUTION: A method for manufacturing a metallic cup having a tapered surface, which expands from a bottom side toward an opening side, on a shank by press molding of a metal plate comprises: a cylindrical body formation process in which a bottomed cylindrical body is formed by drawing and ironing the metal plate; and a tapered surface formation process in which a tapered surface is formed on a shank of the cylindrical body. In the tapered surface formation process, the tapered surface is formed via a diameter reduction process in which a diameter is reduced from a middle position in a lengthwise direction of the cylindrical body to the bottom side, and an expansion process in which a diameter is expanded from the middle position to the opening side.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.

In addition, as a method of manufacturing this metal cup, a metal plate is punched and drawn to form a cup, and the cup is ironed to form a cylindrical vertical wall preform (cylinder) ( DI step), after its open end is rolled to form a curl, a vertical draw having vertical wall sections of continuously decreasing diameter and different heights from the curl to the bottom by a stepwise drawing process. Forming the cup and then widening each of the vertical wall sections using a die having a tapered profile to form a tapered cup with each vertical wall section having a tapered sidewall, and finally the cup. Forming a dome on the bottom is described.

JP 2020-508874 A

By the way, the step of forming the cylindrical body before forming it into a tapered metal cup is formed by drawing and ironing, which is commonly used for so-called two-piece beverage cans, so existing equipment can be used. Efficient if possible. The existing manufacturing equipment forms a cylindrical body with a diameter of about 66 mm, which is a size that is easy to hold.

However, 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. In order to achieve the same capacity as existing cylinders, it is necessary to make the cup elongated. 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.

SUMMARY OF THE INVENTION It is an object of the present invention to manufacture a tapered metal cup having a relatively large diameter while enabling the use of existing equipment.

The method for producing a metal cup of the present invention is a method of press-molding a metal plate to produce a metal cup having a body portion with a tapered surface that expands in diameter from the bottom side toward the opening side. A cylindrical body forming step of forming a bottomed cylindrical cylindrical body by drawing and ironing a plate; forms the tapered surface through a diameter reducing step in which the diameter is reduced from an intermediate position in the length direction of the cylindrical body to the bottom side, and a diameter expanding step in which the diameter is enlarged from the intermediate position to the opening side.

Since the processing method is divided between the bottom side and the opening side from the middle position of the cylinder in the length direction, and the diameter reduction process is performed only on the bottom side, the cylinder formed using the existing cylinder forming equipment is used. Even if it is used, it is possible to form the diameter of the bottom of the metal cup having a tapered surface larger than that of the cup described in Patent Document 1, and the metal cup as a whole can have a relatively large diameter.
In addition, since the diameter reduction process and the diameter expansion process are performed only in the range from the middle position of the cylinder to, for example, half the length, the deformation rate (diameter reduction rate and diameter expansion rate) of each processing is patented It can be made smaller than the method described in Document 1, it is possible to suppress the occurrence of wrinkles and cracks, and it is possible to form a smooth tapered surface, and it is also possible to reduce the thickness of the material.
Of course, as the cylindrical body forming step, it is possible to divert existing equipment used for ordinary two-piece cans as they are.

In the method for manufacturing a metal cup of the present invention, the diameter-enlarging step can be performed after the diameter-reducing step.

Further, in the method for manufacturing a metal cup of the present invention, the diameter-enlarging step is performed prior to the diameter-reducing step, and the opening end of the intermediate cylindrical body after the diameter-expanding step includes an end portion including the edge. It is preferable to carry out a curling step for forming a curled portion by folding back, and to carry out the diameter reducing step after the curling step.

In the diameter-expanding process, the bottom of the cylindrical body is held and punched from the side of the opening. The process is a process of holding the opening side and reducing the diameter of the bottom side. At this time, if the opening of the cylindrical body remains in the shape of a cylindrical sharp edge in the cylindrical body forming process or the diameter expanding process, it is easy to deform in the radial direction, and it is not easy to hold it stably. . By performing the diameter-expanding step and the curling step first as described above, it is possible to perform the diameter-reducing step while holding the curled portion formed at the open end, and the curled portion is not deformed. In addition, since the flat surface can be brought into contact with the can axial direction, it is easy to hold, stable processing can be performed, and a smooth tapered surface can be formed.

In the case where the diameter reduction process is performed before the diameter expansion process, even if a slight deformation such as an elliptical cross section occurs at the opening end during the diameter reduction process, the diameter is expanded by the diameter expansion process after that. Therefore, the opening end can be corrected to have a circular cross section.

According to the present invention, since the diameter of the bottom side is reduced by the diameter reduction process and the diameter of the opening side is expanded by the diameter expansion process from the middle position in the length direction of the cylinder, it is possible to use existing equipment. At the same time, it is possible to manufacture a cup having a larger diameter than the cup described in Patent Document 1.

1 is a front view of a metal cup manufactured by a manufacturing method according to an embodiment of the present invention, with half taken as a longitudinal section centering on the can axis. FIG. It is a flow chart which shows a manufacturing method of a 1st embodiment. FIG. 3 is a front view of a cylindrical body obtained in a cylindrical body forming step, with half of the can axis taken as a center in longitudinal section. It is the longitudinal cross-sectional view of the principal part which shows the state currently processed by the diameter reduction process in order of (a) and (b). FIG. 5 is a front view showing a state in which a stepped portion is formed on the bottom side of the cylindrical body by the mold set of FIG. It is a lower front view which shows the 1st intermediate cylinder body after a diameter-reduction process in (a), and shows the 2nd intermediate cylinder body after a diameter-expansion process in (b) in a half section. It is the longitudinal cross-sectional view of the principal part which shows in order of (a) and (b) the state which forms the stepped part by the diameter-expanding process, and is shaping the stepped part in the taper shape. FIG. 4 is a cross-sectional view showing a state of processing with a curling tool in a curling process; It is a flowchart which shows the manufacturing method of 2nd Embodiment of this invention. It is the front view which made the half section which shows the 3rd intermediate cylinder after a diameter-expanding process in (a), and shows the 4th intermediate cylinder after a curling process in (b).

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 opening 3 has a larger diameter, and has a tapered body 4 whose diameter gradually expands from the bottom 2 toward the opening 3 as a whole. A curled portion 5 is formed by being wrapped around. Let the can axis C be the center of the metal cup 1 in the radial direction.

The body portion 4 has a straight cylindrical portion 12 along the can axis C near the opening 3, and the diameter of the upper cylindrical portion 12 gradually decreases from the lower end to the bottom (the diameter gradually decreases from the bottom to the opening). A tapered cylindrical portion 15 having a tapered surface 15a is formed.

These dimensions are not necessarily limited. 70 mm or more and 95 mm or less, the length H4 from the upper end of the curled portion 5 to the upper end of the upper step portion 14 is 8 mm or more and 20 mm or less, and the angle θ of the tapered cylindrical portion 15 with respect to the horizontal plane is 80° or more and 85° or less. be done.

Next, a method for manufacturing the metal cup 1 will be described.
As shown in FIG. 2, the metal cup 1 is formed by drawing and ironing a metal plate to form a cylindrical body 21 with a bottom (see FIG. 3), and after the cylindrical body forming process. , while using a set of a plurality of molds having different outer diameters in descending order of the outer diameter, the portion of the cylindrical body 21 closer to the bottom 24 than the intermediate position (for example, half position) of the height of the body 23 is opened 22 . By gradually reducing the diameter from the side to the bottom portion 24 side to form a tapered shape, a first intermediate cylindrical body 41 as shown in FIG. A second intermediate cylinder 42 (see FIG. 6B) having a tapered surface 15a is formed by gradually increasing the diameter of the rest of the body from the bottom 2 side to the opening 22 side to form a tapered shape. and a curling step of forming the curled portion 5 at the open end of the second intermediate cylindrical body 42 . That is, the tapered surface forming process for forming the tapered surface 15a is performed by dividing the diameter reducing process and the diameter expanding process. The order of steps will be described below.

[Cylinder Forming Step]
In the cylindrical body forming step, as shown in FIG. 3A, a plate material made of aluminum or an aluminum alloy is punched and drawn to form a cup 25 having a larger diameter and a shallower depth than the cylindrical body 21 in the next step. In addition to the forming step, drawing and ironing (drawing and ironing) are applied to the cup 25 to form a cylindrical body 21 having a diameter smaller than that of the cup 25 and a predetermined height as shown in FIG. 3(b). and a drawing and ironing step. A bottom portion 24 of the cylindrical body 21 is formed substantially flat.

[Diameter reduction process]
In this diameter-reducing step and the subsequent diameter-expanding step, the shape of the body portion 23 of the cylindrical body 21 gradually changes. The cylindrical body formed at the end of the diameter-expanding process is referred to as the second intermediate cylindrical body 42, and the cylindrical bodies formed in the intermediate processes up to that time are the cylindrical body 21, the first intermediate cylindrical body 41, or the second intermediate cylindrical body. Description will be given by attaching one of the reference numerals of the body 42 .

A mold set 31 shown in FIG. 4 is used in the diameter reduction step. The mold set 31 includes a punch 32 inserted into the body 23 of the cylindrical body 21 , a cylindrical wrinkle holding ring 33 arranged so as to surround the punch 32 , and a cylindrical wrinkle holding ring 33 disposed outside the body 23 When the body 21 is pushed in from the side of the bottom part 24, it is composed of a ring-shaped die 34 whose diameter is reduced while holding a part of the cylindrical body 21 between it and a wrinkle suppressing ring 33. These die sets 31 are arranged in descending order of diameter. By using a plurality of sets, the cylindrical body 21 is gradually reduced in diameter.

Specifically, first, using the die set 31 having the largest diameter, the punch 32 and wrinkle suppressing ring 33 are inserted into the cylindrical body 21, and the ring-shaped die 34 is arranged coaxially therewith. The ring-shaped die 34 is formed to have an inner diameter substantially the same as that of the wrinkle-retaining ring 33, and is formed so that the tip facing the wrinkle-retaining ring 33 is inclined in the same direction and at approximately the same angle as the wrinkle-retaining ring 33. there is As shown in FIG. 4, the tip of the wrinkle holding ring 33 is inclined in a direction of decreasing height radially outward, and the ring-shaped die 34 is inclined radially outward in height. is inclined in the direction of increasing

Then, the punch 32 and the wrinkle holding ring 33 and the ring-shaped die 34 are moved relative to each other so that a part of the cylindrical body 21 is formed between the tip of the ring-shaped die 34 and the tip of the wrinkle holding ring 33 . is squeezed into the ring-shaped die 34 to draw the cylindrical body 21, the outer diameter of the cylindrical body 21 is reduced to about half the length of the cylindrical body 21. As a result, as shown in FIG. 5, the cylindrical body 21 has a trunk portion 23A having the same outer diameter as that shown in FIG. becomes smaller and a stepped portion 44 is formed therebetween.

Next, the mold set with the next largest diameter is drawn in the same manner, but at this time, the length of the drawing is set so that it ends before the previously drawn position (on the side of the bottom 24 from the step 44). set to As a result, a stepped portion 44 is further formed closer to the bottom portion 24 than the stepped portion 44 , and the diameter of the body portion 43 closer to the bottom portion 24 than the stepped portion 44 is further reduced. By repeating this operation with mold sets having different diameters in descending order of diameter, as shown by the two-dot chain line in FIG. A stepped portion 44 is formed.

After that, a punch (not shown) having a tapered outer peripheral surface is inserted into the cylindrical body 21 to shape the stepped portion 44 into a smooth tapered shape. Approximately half of the bottom side is formed into a tapered surface whose diameter gradually decreases toward the bottom side to form the first intermediate cylindrical body 41 shown in FIG. 6(a). In this case, the bottom portion 2 has a smaller diameter than the bottom portion 24 of the cylindrical body 21 and has the same outer diameter and shape as the bottom portion 2 of the metal cup 1 in the final shape. In the first intermediate cylindrical body 41, a tapered body portion 46 whose diameter is gradually reduced toward the bottom portion 2 side from an intermediate portion in the length direction (height direction) is formed. A straight cylindrical body portion 23A having the maximum diameter of the portion 46 is left.

[Diameter expansion process]
In the diameter-expanding step, the tapered surface is formed from the intermediate portion in the height direction to the opening portion 22 side so as to be continuous with the tapered surface of the tapered trunk portion 46 of the first intermediate cylindrical body 41 formed in the diameter-reducing step. do. In this diameter-expanding step, while using a plurality of punches 51 and 52 shown in FIG. 23A, a stepped portion forming step of forming a stepped portion 53 having a larger diameter on the opening 22 side than the diameter on the bottom portion 2 side by a stepped portion forming punch 51, and a taper surface while expanding the stepped portion 53 by a shaping punch 52. 54 is sequentially repeated to form a tapered surface on the side of the opening 22 that is continuous with the tapered surface of the tapered trunk portion 46 on the side of the bottom portion 2 formed in the diameter reduction step. As shown in (b), a second intermediate cylindrical body 42 is formed having a tapered cylindrical portion 15 with a tapered surface 15a for most of the trunk portion.

In this case, the stepped portion 53 is first formed by the stepped portion forming punch 51 in the stepped portion forming step, the stepped portion 53 is tapered by the shaping punch 52 in the shaping step, and then the previously formed stepped portion is formed. The next stepped portion is formed slightly closer to the opening 22 than the position of the portion 53, and the stepped portion is shaped. While alternately repeating the stepped portion forming step and the shaping step, the opening is made from the bottom portion 2 side. The trunk portion 23A is gradually tapered toward the portion 22 side. Since this diameter-expanding process is a process for expanding the metal material radially outward from the inner peripheral side of the first intermediate cylindrical body 41, wrinkles are less likely to occur.
At the top of the second intermediate cylindrical body 42 in the final shape in this diameter-enlarging process, the upper-stepped-part forming process for forming the upper stepped part 14 is performed lastly, and thus the diameter-expanding process is finished. .
After forming the upper stepped portion 14, the upper cylindrical portion 12A formed closer to the opening 22 than the upper stepped portion 14 is left straight.

[Curl process]
After the diameter-expanding step, the curled portion 5 is formed by winding the end portion including the edge of the upper cylindrical portion 12A of the second intermediate cylindrical body 42 radially outwardly. In this curling process, as shown in FIG. 8, a plurality of curling tools 71 and 72 are used. The curling tools 71 and 72 are rotatable about axes C1 and C2 extending in a direction crossing the can axis C, and have forming grooves along their circumferential direction. The curling tools 71 and 72 are rotated around the upper cylindrical portion 12A while being pressed against the opening end of the second intermediate cylindrical body 42 in the direction of the can axis C, so that the edges of the upper cylindrical portion 12A are bent by the shaping grooves. The curled portion 5 is formed by folding while expanding the end portion including.

In this curling process, the curling tools 71 and 72 press the second intermediate cylindrical body 42 in the can axis C direction. 12A, and the effect of work hardening due to the previous diameter-reducing and diameter-expanding steps, buckling and deformation are less likely to occur.
In FIG. 8, reference numeral 73 denotes a holder that holds the bottom portion 2 of the first intermediate cylinder 41 and the second intermediate cylinder 42 after molding. After holding, the held state is maintained even during the diameter expanding process and the curling process.

The metal cup 1 manufactured in this manner has a straight cylindrical portion 12 with a slight length near the opening 3, and most of the body portion 4 on the bottom side of this cylindrical portion 12 extends from the bottom portion 2. It is formed in a tapered shape that gradually increases in diameter toward the opening 3 .
In addition, since the curled portion 5 is formed in the opening 3, the mouthfeel is smooth.

Next, a second embodiment of the method for manufacturing the metal cup 1 will be described.
In the manufacturing method of the second embodiment, as shown in FIG. 9, the cylindrical body forming step is the same as in the first embodiment, but after that, contrary to the first embodiment, the diameter expanding step precedes the diameter reducing step. , and a curling process is performed between the diameter-expanding process and the diameter-reducing process.

That is, after the cylindrical body forming step, a plurality of punches 51 and 52 having different outer diameters are used in ascending order of the outer diameter, and the punches 51 and 52 are pushed into the cylindrical body 21 from the opening 22 side to form the cylindrical body 21 . The portion closer to the opening 22 than half the height of the body 23 is gradually expanded from the bottom 24 toward the opening 22 to form a third intermediate cylindrical body 61 that is tapered. a curling step of forming the curled portion 5 at the open end of the third intermediate cylinder 61; and a diameter reduction step of forming the metal cup 1 by reducing the diameter to form a tapered shape. In the second embodiment, a tapered surface forming step is performed in which the tapered surface 15a is formed by the diameter expanding step and the diameter reducing step after the curling step.

[Diameter expansion process]
In the diameter-expanding step, the diameter of the opening 22 side is gradually expanded from the intermediate portion in the height direction of the trunk portion 23 while the bottom portion 24 of the cylindrical body 21 is held. The diameter-expanding method is the same as in the first embodiment. The holding of the bottom 24 of the cylindrical body 21 is the same as that of the holder 73 shown in FIG. be. In the obtained third intermediate cylinder 61, the body 23 of the cylinder 21 remains cylindrical on the bottom 24 side, and the body 23B has a tapered cylinder whose diameter gradually increases toward the opening 22. It becomes the shape where 62 was formed. Also in this case, as in the case of the first embodiment, the upper stepped portion 14 is formed near the opening end, leaving the upper cylindrical portion 12A.
[Curl process]
Next, the curling process is also the same as in the first embodiment, and the curled portion 5 is formed by folding back the end including the edge of the open end. FIG. 10(b) shows the fourth intermediate cylindrical body 63 after the curling process.
[Diameter reduction process]
In the diameter reduction process, as in the first embodiment, a stepped portion is formed using a plurality of die sets each including a punch 32, a wrinkle holding ring 33, and a ring-shaped die 34, and the stepped portion is shaped into a tapered shape. It is a way to

In this second embodiment, the diameter reduction process is performed after the curling process is performed. In this diameter reduction step, the curled portion 5 is formed in the opening 3 of the fourth intermediate cylindrical body 63, so that the mechanical strength of the opening 3 is improved. By processing the bottom side (23B) of the barrel, stable processing can be carried out. In the case of the above-described first embodiment as well, in the diameter reduction process, the processing is performed while holding the opening side, but in the case of the first embodiment, the opening 22 is a straight cylindrical edge. (See FIG. 6(a)), radial deformation is easy. Therefore, in the first embodiment, when holding the opening 22, it is necessary to hold the opening 22 from the inside and the outside, which complicates the structure.
In the case of the second embodiment, since the curled portion 5 has high rigidity and the open end is an arcuate surface, the tip can be brought into contact and held stably.

In the above embodiment, in the diameter reduction step, after forming a plurality of stepped portions along the direction of the can axis C, these stepped portions are shaped into a tapered surface. may be formed into a tapered surface, and then the next step may be formed to form a tapered surface.

On the other hand, 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 the stepped portion to shape it into a tapered surface. The steps of forming the stepped portion and the shaping step were alternately repeated, but by performing the stepped portion forming step a plurality of times, after forming a plurality of stepped portions along the can axis C, these stepped portions were removed from the bottom side. It is also possible to shape them sequentially 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 gist of the present invention.

C Can Shaft 1 Metal Cup 2 Bottom 3 Opening 4 Body 5 Curl 12 Upper Cylinder 14 Upper Step 15 Tapered Cylinder 15a Tapered Surface 21 Cylinder 23 Body 24 Bottom 25 Cup 31 Mold Set 32 Punch 33 Wrinkle holding ring 34 Ring-shaped die 41 First intermediate cylinder 42 Second intermediate cylinder 43 Body 44 Stepped part 46 Tapered body 51 Stepped part forming punch 52 Shaping punch 61 Third intermediate cylinder 62 Tapered cylinder 63 fourth intermediate cylinders 71, 72 curling tool 73 holder

Claims (3)

A method of press-molding a metal plate to produce a metal cup having a tapered surface on the body portion that expands in diameter from the bottom side toward the opening side, wherein the metal plate is drawn and ironed to form a bottomed cylinder. and a tapered surface forming step of forming the tapered surface on the body of the cylindrical body,
The tapered surface forming step includes a diameter reducing step in which a diameter is reduced from an intermediate position in the length direction of the cylindrical body toward the bottom side, and a diameter increasing step in which the diameter is increased from the intermediate position toward the opening side, and then the tapered surface is formed. A method of manufacturing a metal cup, characterized by forming a 2. The method of manufacturing a metal cup according to claim 1, wherein the diameter-enlarging step is performed after the diameter-reducing step. The diameter-expanding step is performed prior to the diameter-reducing step, and a curling step is performed to form a curled portion by folding back the end including the edge to the opening end of the intermediate cylinder after the diameter-expanding step. 2. The method of manufacturing a metal cup according to claim 1, wherein said diameter reducing step is carried out after said curling step.

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