JP2023018674A - Metallic cup manufacturing method - Google Patents

Abstract

To manufacture a metallic cup which can easily handle a cylindrical body and can be stacked.SOLUTION: A metallic cup is formed via the following processes: a cylindrical body formation process in which a cylindrical body with a bottom is formed by drawing and ironing a metal plate; a diameter expansion process in which a lower cylindrical part provided near the bottom of the cylindrical body is held by a chuck, a punch is pushed into the cylindrical body from an opening end side, and a diameter of a shank of the cylindrical body is radially expanded from the bottom side toward the opening end side, thereby forming an intermediate cylindrical body having a tapered cylindrical part; and a curling process in which a curl part is formed by folding the opening end of the intermediate cylindrical body while maintaining the state that the cylindrical part is held by the chuck.SELECTED DRAWING: Figure 1

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, metal, paper, and plastic cups are lighter than ceramic and glass cups, and are more convenient to carry. In particular, cups made of aluminum metal are excellent in terms of strength, and in recent years, they have been attracting attention from the viewpoint of environmental considerations.

Patent Literature 1 describes a method for manufacturing a metal cup as a deformable container. This deformable container has a diameter-reduced portion or a diameter-increased portion formed in a part of the body portion of a cylindrical container with a bottom. In order to manufacture this deformable container, first, a cylindrical container with a bottom is formed by impact molding, and then a part of the body is reduced or expanded by a necking machine, and then a bead ( curled portion). However, in the deformable container described in Patent Document 1, it is not possible to stack a plurality of deformable containers.

Patent Document 2 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, since the diameter of the cup gradually increases from the bottom to the opening, it is possible to stack a plurality of 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 bottomed cylindrical vertical wall preform (cylinder) ( DI process), after cutting off the opening edge to set a predetermined height, the opening edge is rounded to form a curled portion, and then a stepwise drawing process is performed to form a curled portion from the curled portion to the bottom. By forming vertical draw cups having vertical wall sections of different heights and diameters continuously decreasing from the bottom to the bottom, and then widening each of the vertical wall sections using a die having a tapered profile, It describes forming a tapered cup with tapered sidewalls for each vertical wall section and finally forming a domed portion at the bottom of the cup.

Japanese Patent No. 4653196 JP 2020-508874 A

However, as in Patent Document 2, after the cylindrical body is molded, a process of forming a curled portion on the open end, a step of gradually reducing the diameter of the body of the cylindrical body, and then a process of forming a domed portion on the bottom, respectively. In the process of (1), it is necessary to process the portion for holding the cylindrical body while changing the holding position.

SUMMARY OF THE INVENTION It is an object of the present invention to manufacture a metal cup that can be easily handled and stacked using simple equipment.

A method for manufacturing a metal cup according to the present invention includes a cylindrical body forming step of forming a cylindrical body having a bottom by drawing and ironing a metal plate, and providing a cylindrical body near the bottom after the cylindrical body forming step. The lower cylindrical portion thus formed is held by a chuck, and 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. forming a diameter-expanding step of forming an intermediate cylindrical body having a tapered cylindrical portion; and forming a curled portion by folding back the open end portion of the intermediate cylindrical body while maintaining a state in which the lower cylindrical portion is held by the chuck. and a curling step to form a metal cup.

After the cylindrical body forming process, the lower cylindrical part of the cylindrical body is held by a chuck, and the diameter expanding process and the curling process can be continuously performed in the held state. Since it is not necessary to change the holding of the cylinder, handling of the cylinder is easy and equipment can be simplified. When manufacturing bottle-shaped cans with a reduced diameter at the upper portion of the body, a necking machine using a so-called die-neck system is used to continuously perform diameter reduction, mouth molding, etc. while indexing. Using such a necking machine, the step of increasing the diameter and the step of forming the curled portion can be continuously performed while the lower end portion of the cylindrical body is held by the chuck.

Since the lower cylindrical portion of the cylindrical body is always held in the same posture regardless of changes in shape, it is possible to perform stable and accurate processing and obtain a metal cup with little dimensional variation.

In addition, in the manufacturing method described in Patent Document 2, after forming a cylindrical body with a bottom, drawing is performed so as to gradually reduce the diameter from the opening end of the cylindrical body toward the bottom. On the other hand, in the present invention, the cylindrical body is formed so as to gradually expand in diameter from the bottom toward the open end. In other words, while the processing described in Patent Document 2 is processing that presses the metal material radially inward from the outer peripheral side, the present invention is processing that expands the metal material radially outward from the inner peripheral side. Therefore, it is possible to form a smooth tapered body portion that is less prone to wrinkles.

Moreover, since the lower cylindrical portion of the cylindrical body is machined while being held by the chuck, a smooth and accurate tapered surface can be finished.

Therefore, the straight cylindrical body before the diameter-expanding process can be stably and accurately processed into the intermediate cylinder. It is possible to facilitate so-called partial magnification printing in which magnification is taken into account.

Furthermore, the drawing and ironing process for forming the 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 2, 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.

The method for manufacturing a metal cup of the present invention preferably includes a cup cleaning step of cleaning the inner surface of the metal cup after the curling step.

Since the diameter of the opening end is larger than that of the bottom, the water can be easily drained when the inside is washed, and the inner surface after punching can be cleaned by providing a cup washing process after the curling process.

In the method for manufacturing a metal cup of the present invention, it is preferable to include a trimming step of trimming the open end of the intermediate cylindrical body between the diameter-expanding step and the curling step.

Although the height of the open end may vary in the circumferential direction because it is expanded in the radial direction in the diameter-expanding process, the curling process can be performed accurately and smoothly by aligning the heights in the trimming process.

The method for manufacturing a metal cup of the present invention preferably includes a packing step of continuously manufacturing the metal cups and packing a plurality of the metal cups in a stacked state.

Since the diameter of the open end is larger than that of the bottom, stacking is easy, and the packaging volume can be reduced, which is economical because transportation costs and the like can be reduced.

In the metal cup manufacturing method of the present invention, after the cylindrical body forming step and before starting processing in the diameter expanding step, a substantially cylindrical posture correcting punch is inserted into the cylindrical body held by the chuck. Then, a posture correcting step may be further performed to match the can axis of the cylindrical body with the processing axis of the punch.

By performing the posture correcting step before the diameter expanding step, it is possible to prevent the cylindrical body from being crushed by the forming tool while being tilted and held.

The posture correcting punch has a tip portion smaller than the inner diameter of the barrel and a rear end portion with an outer diameter that is the same as or slightly larger than the inner diameter of the barrel. It is preferable that the diameter expands smoothly toward the part.

Since the tip of this posture correcting punch is thinner than the cylindrical body, it can be reliably inserted even if the cylindrical body (work) is tilted. By inserting the rear end of the workpiece with an outer diameter that is the same as or slightly larger than the inner diameter of the workpiece, the inner diameter of the workpiece and the outer diameter of the rear end match without gaps to the extent that the workpiece does not crack. The can axis of the tool can be reliably matched with the machining axis of the tool. In addition, since the posture correcting punch smoothly expands its diameter, even if the punch moves while contacting the work, the work will not be caught by the punch and deformed or crushed.

According to the present invention, stackable metal cups can be manufactured with simple equipment in which handling of the cylinder is easy.

It is a flowchart which shows the outline of the manufacturing method of one Embodiment of this invention. 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. FIG. 3 is a front view of a cylindrical body obtained in a drawing and ironing step in a cylindrical body forming step, with half of the cylindrical body centering on the can axis taken as a vertical cross-sectional view. FIG. 4 is a front view of the metal cup manufacturing apparatus for performing the diameter-expanding process to the curling process. FIG. 5 is a cross-sectional view taken along line AA of FIG. 4; FIG. 5 is a vertical cross-sectional view of a main part showing a stepped portion forming step in the diameter expanding step; FIG. 10 is a vertical cross-sectional view of a main part showing a shaping step after a stepped portion forming step; FIG. 4 is a vertical cross-sectional view of the main part showing the workpiece in a shaped state; FIG. 4 is a cross-sectional view showing a state of processing with a curling tool in a curling process; It is a figure which shows the attitude|position correction process performed before a diameter-expanding process. It is a partial enlarged view showing the rear end portion of the posture correcting punch.

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 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 tapered cylindrical portion 15 with respect to horizontal plane: 80° or more and 85° or less (on the inner surface side of the cross section including can axis C) Connects lower cylindrical portion 11 and lower step portion 13 Curve radius R: 8 mm or more and 24 mm or less

Next, a method for manufacturing the metal cup 1 will be described. As shown in FIG. 1, the metal cup 1 is formed by drawing and ironing a metal plate to form a cylindrical body 21 having a bottomed cylindrical body, and after the cylindrical body forming process, the cylindrical body 21 is formed. A cylindrical body cleaning step of washing and drying, a printing/coating step of printing on the outer peripheral surface of the body portion 23 of the cylindrical body 21 after the cylindrical body cleaning step, and coating the outer surface and the inner surface, and after the printing/coating step, While using a plurality of punches having different outer diameters in ascending order of outer diameter, the punches are pushed into the cylindrical body 21 from the open end 22 side, and the body part 23 of the cylindrical body 21 is directed from the bottom part 2 side to the open end part 22 side. A step of gradually expanding the diameter to form the tapered tubular portion 15 and forming the intermediate tubular body 50, and cutting the open end of the intermediate tubular body 50 formed by this diameter expanding step to a predetermined height. A trimming step of forming the bottom, a curling step of forming the curled portion 5 at the open end of the intermediate cylindrical body 50 after trimming to form the metal cup 1 in the final shape (see FIG. 9), and a metal It is manufactured through processes including a cup washing process of washing and drying the cup 1 and a packing process of packing the washed metal cup 1 after inspecting it. 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. 3(a)). a drawing and ironing process of drawing and ironing (drawing and ironing) the cup 25 to form a bottomed cylindrical cylindrical body 21 having a diameter smaller than that of the cup 25 and a predetermined height (FIG. 3(b)); I do. 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. are doing. The cup forming process and the drawing and ironing process are the same as those of a normal beverage can manufacturing process.

[Cylinder cleaning process]
The cylindrical body 21 is dried after being washed. A conversion coating treatment may be performed between washing and drying. In addition, this step may be omitted when lubricating oil is not used for cylindrical body forming and cleaning is not required, for example, when a covering plate is used for a metal plate as a material.

[Printing/painting process]
After the cylindrical body cleaning process, the cylindrical body 21 is degreased and chemically treated, and then supplied to a printing device (not shown) to print on the outer peripheral surface of the body portion 23 . Next, it is supplied to a coating device to form a transparent outer coating (overcoat or finishing varnish) on the entire outer peripheral surface including the printed layer, and the coated cylindrical body 21 is passed through an oven to pass the printed layer and the outer coating. Bake the membrane. Next, the inner surface of the cylindrical body 21 is painted to form an inner coating film, which is passed through an oven and baked.

In addition, for example, when a coating plate is used for a metal plate as a material and the coating plays the role of an outer coating film or an inner coating film, or when printing or labeling is performed after cup molding, this process (printing / painting process) can be omitted.

[Expanding process, trimming process and curling process]
A metal cup manufacturing apparatus (hereinafter simply referred to as a manufacturing apparatus) 501 shown in FIGS. 4 and 5 is used from the diameter expanding process to the curling process. This manufacturing apparatus 501 is for processing the cylindrical body 21 formed as described above into the metal cup 1 of the final shape, and sequentially performs a diameter-enlarging process, a trimming process, and a curling process.

For this reason, the shape of the can changes according to the progress of processing, but in the case where the shape of the bottomed cylindrical can in the intermediate stage from the cylindrical body 21 to the intermediate cylindrical body 50 in the diameter expanding process is not particularly limited. will simply be described as a workpiece W as the object to be processed by the manufacturing apparatus 501 . Further, since the cylindrical body 21, the intermediate cylindrical body 50 and the metal cup 1 are also handled by the manufacturing apparatus 501, they may be referred to as the workpiece W for convenience.

This manufacturing apparatus 501 includes a work holding section 511 for holding a plurality of works W (including the cylindrical body 21, the intermediate cylindrical body 50, and the metal cup 1) with the can axis C direction thereof arranged horizontally, and these works A tool holding portion 513 for holding a plurality of forming tools 512 for performing various forming processes, etc., and a driving portion 514 for driving both holding portions 511 and 513 are provided. A work holding side of a work holding portion 511 holding a work W and a tool holding side of a tool holding portion 513 holding a forming tool 512 are arranged to face each other.

The work holding unit 511 includes a chuck 517 that holds the work W, a disc 516 that holds the chuck 517 , and a support shaft 515 that supports the disc 516 . The chucks 517 are arranged annularly along the circumferential direction on the surface of the disc 516 facing the tool holding portion 513 . The chuck 517 abuts on the rim portion 8 at the bottom of the work W and holds the lower cylindrical portion 11 at the lower end of the body portion.

More specifically, the chuck 517 includes a cup-shaped main body 517A that accommodates the lower portion of the work W, and an annular balloon 517B held by the main body 517A. In this chuck 517, the rim portion 8 of the bottom portion of the work W is brought into contact with the bottom portion of the main body 517A, and the inside of the dome portion 6 is made negative pressure by a vacuum mechanism (not shown) to suck and hold the work W, and air is supplied. A balloon 517B inflated by a mechanism (not shown) is inflated from the inner peripheral surface of the main body 517A to press the lower cylindrical portion 11 inward and hold it.

By intermittently rotating the disk 516 about the support shaft 515 by the drive unit 514, the cylindrical body 21 supplied from the supply unit 518 via the supply side star wheel 519, as shown in FIG. The wafers are held one by one by the chuck 517 and conveyed in the circumferential direction of the disc 516 .

The cylindrical body 21 is formed by each forming tool 512 of the tool holding portion 513 while being conveyed by the disk 516, and then sequentially discharged to the discharge portion 611 via the discharge side star wheel 601 as a metal cup after forming.

The tool holding portion 513 includes a disk 613 holding various forming tools 512 and a support shaft 612 supporting the disk 613 . A plurality of various forming tools 512 are arranged annularly along the circumferential direction so as to be able to face individual chucks 517 on the surface of the disk 613 facing the work holding portion 511 . It is configured to move forward and backward. The support shaft 612 is provided coaxially with the support shaft 515 inside the support shaft 515 .

A plurality of forming tools 512 provided in the tool holding portion 513 are inserted into the workpiece W and form the intermediate cylindrical body 50 while gradually increasing in diameter from the bottom portion 2 side toward the opening end portion 22 side. , a cutting tool for trimming, and a curled portion forming tool for forming the curled portion 33, etc., and processing can be performed according to each processing step. These forming tools 512 are annularly arranged on a disk 613 in the order of processes.

The intermittent rotation stop position of the work holding portion 511 (disk 516) about the axis of the support shaft 515 is such that the can axis C of each work W with the opening facing the tool holding portion 513 is positioned at each molding tool 512. are set so as to coincide with the central axes of the By intermittent rotation of the disk 516 by the drive unit 514, each work W is rotationally moved to a position facing each forming tool 512 for the next process, and processed in the next stage.

That is, when the tool holding portion 513 advances and the work holding portion 511 and the tool holding portion 513 approach each other, each forming tool 512 processes the work W according to each process, and both holding portions 511 and 513 are separated from each other, the workpiece holder 511 is rotationally moved so that the molding tool 512 for the next process faces each workpiece W. As shown in FIG. In this manner, the workpiece W is processed and the metal cup 1 is formed by repeating the operation of the two holding parts 511 and 513 approaching each other for processing, separating and rotating.

During this time, the work W is maintained in a state in which the bottom portion 2 and the lower cylindrical portion 11 are held by the chuck 517 of the work holding portion 511 regardless of the change in shape from the state of the cylindrical body 21 before processing. By the intermittent rotation of 511, it is made to face each forming tool 512 of the tool holding part 513 sequentially, and the diameter expanding process, the trimming process and the curling process are sequentially performed.

Each of the diameter expanding process, the trimming process, and the curling process will be described below.

[Diameter expansion process]
In the diameter-expanding step, a stepped portion forming step consisting of a plurality of steps of forming a stepped portion having a larger diameter on the opening side than the diameter on the bottom portion 2 side on the body portion of the work W, and expanding the stepped portion to form a tapered surface. By sequentially repeating the shaping step of shaping into a straight shape, the intermediate cylindrical body 50 shown in FIG. 3(c) is formed.

In the step forming step, as shown in FIG. 6, a stepped punch 41 is inserted into the workpiece W from the opening end in the axial direction as indicated by the arrow, and the stepped portion 42 of the stepped punch 41 is pressed against the workpiece W. , a stepped portion 43 is formed to increase the diameter of the opening end side from the bottom portion 2 side (see FIG. 7).

In the shaping step, as shown in FIG. 7, a shaping punch 51 having a tapered shaping surface 52 is axially inserted into the opening of the workpiece W to form the stepped portion 43 formed in the stepped portion forming step on the tapered surface. 53 (see FIG. 8).

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 of the workpiece W. As shown in FIG. Above the upper stepped portion 14 is a straight cylindrical upper cylindrical portion 12' (see FIG. 3(c)).

During this series of steps, the lower cylindrical portion 11 below the lower stepped portion 13 is kept held by the chuck 517 . Accordingly, the lower cylindrical portion 11 is left straight below the lower stepped portion 13 .

[Trimming process]
Since the work W is expanded in the diameter direction in the diameter expanding process, variations in the height of the opening edge of the work W are likely to occur as if the opening edges of the work W undulate in the circumferential direction due to variations in the partial elongation of the material. Therefore, a trimming process using a cutting tool is performed to cut off the opening end to make the heights uniform. Also at this time, the workpiece W is maintained in a state of being held by the chuck 517 . Through this trimming process, the workpiece W becomes the intermediate cylindrical body 50 .

[Curl process]
Next, the curled portion 5 is formed by winding while folding back the end including the edge of the upper cylindrical portion 12 ′ of the intermediate cylindrical body 50 radially outward. In this curling process, as shown in FIG. 9, 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, while pressing the curling tool 71 against the open end of the intermediate cylindrical body 50 in the direction of the can axis C, the edge of the upper cylindrical portion 12' is covered by the forming groove 72 by turning around the upper cylindrical portion 12'. The curled portion 5 is formed by folding the ends while expanding them.

Also in this curling process, the lower end of the workpiece (intermediate cylindrical body 50) W is kept held by the chuck 517. As shown in FIG.

In this curling process, the curling tool 71 presses the intermediate cylindrical body 50 in the can axis C direction. , 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 a straight lower cylindrical portion 11 and an upper cylindrical portion 12 of some length near the bottom portion 2 and the open end portion 3, and most of the body portion 4 therebetween. is formed in a tapered shape that gradually increases in diameter from the bottom portion 2 toward the open end portion 3 . In this manufacturing method, the steps of forming a stepped portion 43 having a larger diameter on the side of the opening end portion 22 than on the side of the bottom portion 2 of the cylindrical body 21 and then shaping the stepped portion 43 into a tapered shape by expanding the stepped portion 43 are repeated. As a result, the entire trunk 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. In addition, since the stepped portion 43 is first formed and then shaped into a tapered shape, cracks are less likely to occur than when the tapered shape is processed without forming the stepped portion 43 . Therefore, a smooth tapered trunk portion 4 can be formed.

Moreover, since the workpiece is machined while being held by the chuck 517, it is possible to finish the tapered surface smoothly and accurately.

In addition, since the curled portion 5 is formed at the open end portion 3, the texture is also smooth.

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, in the present invention, when a process for changing the diameter of the cylindrical body 21 is performed in a process subsequent to the cylindrical body forming process, only the diameter-enlarging process is performed. In other words, the diameter of the cylindrical body 21 is not reduced.

A series of operations from the diameter-expanding process to the curling process are continuously performed while the lower end of the work W (including the cylindrical body 21, the intermediate cylindrical body 50, and the metal cup 1) is held by the chuck 517. Thus, the posture of the workpiece W during machining can be stabilized, accurate and stable machining can be performed, and the metal cup 1 with little dimensional variation can be obtained.

Also, in the printing/painting process, when printing is applied to the cylindrical body before the diameter-enlarging process, it is possible to facilitate so-called partial-magnification printing, which takes into account the magnification of the deformation during the diameter-expanding process. Designability can also be improved by applying correct printing without defects.

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. It is also possible to shape the parts one by one from the bottom side. It is also possible to collectively shape two or more stepped portions.

In the present invention, in the diameter-expanding process, if diameter-expanding is performed using the manufacturing apparatus 501 in a state where the can axis of the work does not match the machining axis of the forming tool, the work may be crushed. However, from the viewpoint of productivity, it is desirable that the apparatus can continue to operate without stopping just to correct the can axis of the workpiece.

This situation occurs, for example, when the workpiece tilts due to the movement of the workpiece due to gravitational force or reaction to the movement and is held by the chuck as it is during the period from when the workpiece is moved to the chuck to when it is held. This situation is likely to occur when the workpiece is held by the chuck near the bottom in order to increase the flexibility of the shape of the body, or when the chuck is not equipped with a vacuum mechanism.

On the other hand, it is possible to perform a posture correcting step for correcting the posture of the workpiece before the diameter expanding step. 10, a substantially cylindrical posture correcting punch 520 is inserted into the cylindrical body 21 (workpiece W) held by the chuck 517 before starting processing by each forming tool 512 in the diameter-enlarging process. Then, the can axis C of the cylindrical body 21 is aligned with the machining axis 520C of each forming tool 512. As shown in FIG.

The posture correcting punch 520 is held by the tool holding portion 513 in the same manner as the forming tools 512, and is inserted into the work W held by the work holding portion 511 by bringing the disk 613 and the disk 516 closer together. As a result, the tilted work W is pushed by the posture correcting punch 520, and the tilt of the work W is corrected so that the can axis C coincides with the machining axis 520C of the posture correcting punch 520, so the manufacturing apparatus is stopped to correct the posture. Moreover, even when the vacuum mechanism is not used, it is possible to prevent the work W from being crushed by the forming tool 512 while being held at an angle.

As shown in FIG. 10, the posture correcting punch 520 has a front end portion 520A having an outer diameter smaller than the inner diameter of the cylindrical body 21 and a rear end portion 520B having an outer diameter equal to or slightly larger than the inner diameter of the cylindrical body 21. , and smoothly expands in diameter from the front end portion 520A toward the rear end portion 520B. An enlarged view of the rear end portion 520B is shown in FIG.

The posture correcting punch 520 is inserted into the work W by advancing the posture correcting punch 520 . When the posture correcting punch 520 is further advanced, the outer surface of the posture correcting punch 520 that smoothly expands in diameter from the front end portion 520A to the rear end portion 520B and the inner surface near the opening end portion 22 of the workpiece W where the can axis C is inclined are aligned. When the posture correcting punch 520 is further advanced from here, the inner surface of the workpiece W near the opening end 22 is pushed outward in the radial direction of the concentric cylinder centered on the processing axis 520C of the posture correcting punch 520. The posture of the work W is corrected so that the can axis C coincides with the machining axis 520C.

Since the tip portion 520A of the posture correcting punch 520 is thinner than the work W, the work W can be reliably inserted even if the work W is tilted. Then, by inserting the rear end portion 520B of the outer diameter which is the same as or slightly larger than the inner diameter of the work W into the work W, the inner diameter of the work W and the outer diameter of the rear end portion of the work W are closely spaced to the extent that the work W is not cracked. Since they match, the can axis C of the workpiece W can be reliably matched with the machining axis of the forming tool 512 . Moreover, since the posture correcting punch 520 is smoothly expanded in diameter, even if the punch 520 moves in contact with the work W, the work W will not be caught by the punch 520 and deformed or crushed.

In the posture correcting punch 520, the front end portion 520A and the rear end portion 520B are formed by combining a single curved surface (spherical base, tapered shape, etc.) or a plurality of curved surfaces, and the outer diameter is gently and smoothly rearward from the front end portion 520A. It expands in the direction toward end 520B. As a result, the outer surface of the posture correcting punch 520 is not rapidly enlarged, and damage to the work W can be prevented. By smoothly enlarging the tip portion 520A, when the inclination of the work W is large, the posture can be corrected by the tip portion 520A first. In addition, since the posture correcting punch 520 is smoothly expanded in diameter, even if the posture correcting punch 520 moves while being in contact with the work, the work W will not be caught by the posture correcting punch 520 and deformed or crushed. do not have. The maximum diameter of posture correcting punch 520 is provided at rear end portion 520B.

The posture correcting punch 520 may further include an intermediate portion 520D having a substantially cylindrical surface continuous between the leading end portion 520A and the trailing end portion 520B. Depending on the length of the workpiece W in the can axis C direction, the length of the posture correcting punch 520 can be appropriately set by providing the intermediate portion 520D.

The posture correcting punch 520 is provided so that a gap is formed between the tip portion 520A and the inner surface of the bottom portion 2 of the work W, that is, it does not come into contact with the bottom portion 2 even when the punch 520 moves forward. This can prevent the posture correcting punch 520 from contacting and crushing the work W moving to the next process.

In addition, the above embodiments can be modified as appropriate without departing from the scope of the present invention. For example, the posture correction may be performed by setting the posture correction punch to a length that can contact the bottom of the workpiece and applying the posture correction punch to the bottom. Moreover, the diameter expansion from the front end portion to the rear end portion of the posture correcting punch does not necessarily have to be performed over the entire length of the punch or over the entire length of each portion such as the front end. That is, for example, in addition to the portion where the outer diameter expands in the can axial direction, there may be a portion where the outer diameter is constant or a portion where the outer diameter is reduced.

C can shaft W workpiece 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 Part 15 Taper cylinder part 21 Cylindrical body 22 Open end part 23 Body part 25 Cups 41, 51 Punch 42 Stepped part 43 Stepped part 52 Shaping surface 53 Tapered surface 71 Curling tool 72 Groove for molding 501 Metal cup manufacturing device 511 Work holding unit 512 molding tool 513 tool holding part 514 driving part 515 support shaft 516 disk 517 chuck (holding device)
517A main body 517B balloon 518 supply unit 519 supply side star wheel 520 attitude correction punch 520A front end portion 520B rear end portion 520C processing shaft 520D intermediate portion 601 discharge side star wheel 611 discharge portion 612 support shaft 613 disk

Claims (6)

a cylindrical body forming step of forming a cylindrical body having a bottom portion by drawing and ironing a metal plate;
After the cylindrical body forming step, a lower cylindrical portion provided in the vicinity of the bottom portion of the cylindrical body is held by a chuck, and a punch is pushed into the cylindrical body from the open end side to form the body portion of the cylindrical body on the bottom portion. a diameter increasing step of gradually increasing the diameter from the side toward the opening end side to form an intermediate cylindrical body having a tapered cylindrical portion;
a curling step of forming a curled portion by folding back the open end portion of the intermediate cylinder while maintaining the state in which the lower cylindrical portion is held by the chuck;
A method of manufacturing a metal cup, comprising forming the metal cup through 2. The method of manufacturing a metal cup according to claim 1, further comprising a cup cleaning step of cleaning the inner surface of the metal cup after the curling step. 3. The method of manufacturing a metal cup according to claim 1, further comprising a trimming step of trimming the open end portion of the intermediate cylindrical body between the diameter-expanding step and the curling step. 3. The method for manufacturing a metal cup according to claim 1, further comprising a packing step of manufacturing the metal cups continuously and packing a plurality of the metal cups in a stacked state. After the cylindrical body forming step and before starting processing in the diameter expanding step, a substantially cylindrical posture correcting punch is inserted into the cylindrical body held by the chuck, and the can shaft of the cylindrical body is moved by the punch. 2. The method of manufacturing a metal cup according to claim 1, further comprising a step of correcting the posture to match the processing axis of the metal cup. The posture correcting punch is
a front end portion having an outer diameter smaller than the inner diameter of the barrel and a rear end portion having an outer diameter equal to or slightly larger than the inner diameter of the barrel;
6. The method of manufacturing a metal cup according to claim 5, wherein the diameter is smoothly expanded from the tip portion toward the rear end portion.

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