JP7089398B2 - Manufacturing method of can body - Google Patents

Description

The present invention relates to a method for manufacturing a metal can body filled with contents such as a beverage, and particularly to a method for manufacturing a can body having a reduced diameter shape that is smoothly reduced in diameter on the opening side.

As a container filled with contents such as beverages, it can be used for two-piece cans in which a can lid is wrapped around the opening end of a bottomed cylindrical can body, or for the opening of a bottle-shaped can body (bottle can). Bottle containers and the like equipped with metal caps are known. A can body used for such a container is generally provided with a shoulder portion and a reduced diameter portion (neck portion) whose diameter gradually decreases toward the opening side, and the diameter of the opening side is reduced rather than the bottom side. It is said that.

As a diameter reduction process for forming such a reduced diameter shape, for example, as described in Patent Document 1 or Patent Document 2, a plurality of molding dies are used to sequentially deform the body of the can body to reduce the diameter. A molding method has been proposed in which a tapered surface-like smooth shape (smooth neck) is formed without forming the diameter portion in a stepped shape. In these diameter reduction processes, relative movement is generated between the can body and each molding die along the can axis direction, and the molding surface of each molding die is pressed against the outer surface of the body of the can body multiple times. The diameter of the opening side of the body portion is gradually reduced to form the reduced diameter portion.

On the other hand, in Patent Document 3, after the diameter-reduced portion of the can body is subjected to diameter reduction processing a plurality of times to form a tapered portion, the tapered portion of the can body and the tapered portion are adjacent to the can bottom side by a reform mold. It is described that the convex curved surface portion to be arranged and the concave curved surface portion arranged adjacent to the can bottom of the tapered portion are remolded. In Patent Document 3, even if an indentation is formed on the tapered portion due to the diameter reduction process or a sharp portion is formed on the convex curved surface portion adjacent to the can bottom side of the tapered portion, the taper portion is subsequently remolded. By doing so, the surface of the tapered part can be flattened to eliminate indentations, and the sharp part of the convex curved surface can be rounded to shape it so that it has the desired radius of curvature, which is beautiful for the can body. It is stated that the appearance can be given.

Japanese Unexamined Patent Publication No. 7-185707 Special Table No. 3-502551 Gazette Japanese Unexamined Patent Publication No. 2016-107341

As described in Patent Documents 1 to 3, conventionally, a molding method has been proposed in which a reduced diameter shape of a body portion is formed into a smooth shape having a tapered surface shape without forming a stepped shape. However, if it is attempted to form the reduced diameter shape in a wide region (a long region along the can axis direction), it is necessary to increase the number of moldings by the increased region, and the manufacturing cost increases. Therefore, it is conceivable to increase the amount of processing at one time to shorten the molding process, but the friction between the body and the molding die in one molding increases, so that molding marks are generated on the molded part. It becomes difficult to form a smooth machined surface. Further, as described in Patent Document 3, it is conceivable to remold the tapered portion after the diameter reduction process to eliminate the molding marks, but in order to remold a wide area, the required molding load is large. It may cause buckling of the torso. For this reason, the reduced diameter shape that can be molded by the conventional manufacturing method is very limited, which is a limitation when designing the can body.

The present invention has been made in view of such circumstances, and it is possible to shorten the manufacturing process of the can body and to stably maintain a reduced diameter shape smoothly connected to a wide region along the can axis direction. It is an object of the present invention to provide a method for producing a can body that can be formed.

In the method for manufacturing a can body of the present invention, the cylinder body having a cylindrical body portion is arranged on the planned diameter reduction portion of the body portion from the lower side of the body portion to the opening end side along the can axis direction. The diameter-reduced portion forming step of forming a reduced-diameter portion gradually reduced toward the upper side is provided, and the reduced-diameter portion molding step moves the cylinder and the diameter-reducing mold relative to each other in the can axis direction. By making the diameter reduction process, the molding surface of the diameter reduction mold is pressed against the outer surface of the diameter reduction mold to reduce the diameter of the entire region from the opening end portion of the body portion to the diameter reduction planned portion. , The processing diameter of the molding surface of the diameter reduction mold is reduced stepwise and divided into a plurality of times, and each time the diameter reduction processing is performed, the locally reduced diameter portion molded by each diameter reduction mold. Is formed while shifting the position from the lower side to the upper side, and the pre-diameter portion is formed by forming the pre-reduced portion in which each local diameter-reduced portion is formed at intervals. Remolding by pressing the molding surface of the remolding mold against the outer surface of the pre-diameter portion by relatively moving the cylinder body and the remolding mold in which the shape is formed in the can axis direction. The processing is performed in a plurality of times while gradually reducing the processing diameter of the molding surface of the remolding mold or gradually increasing the processing diameter, and each time the remolding process is performed, each remolding metal is performed. A remolding step of forming the reduced diameter portion having a smoothly continuous outer surface by sequentially crushing a region wider than the distance between the locally reduced diameter portions by a mold so as to be crushed downward in the can axis direction. Of the remolding processes performed a plurality of times in the remolding step, at least one subsequent remolding process performed after the preceding remodeling process newly includes a part of the pre-reduced diameter portion. Is remolded, and the preceding remolding portion remolded in the preceding remolding process is pressed by the molding surface of the remolding mold along the diameter-reduced portion, and from the preceding remolding portion. In the subsequent remolding process, the remolding portion of the subsequent line to be remolded is continuously processed .

In the method for manufacturing a can body of the present invention, the reduced diameter portion forming step is divided into a preforming step and a remolding step. Then, in the preforming step, the pre-reduced portion is formed by forming the locally reduced-diameter portion at intervals in each diameter-reducing process. In this way, in the pre-molding process, it is allowed to form molding marks (concave and convex surfaces) in the pre-reduced diameter portion, so that the amount of one processing in each diameter-reduced machining can be increased and the width is wide along the can axis direction. When forming a reduced diameter shape in the region, it is possible to shorten the manufacturing process of the can body. Further, in the remolding step, the pre-reduced portion where the molding mark remains is remolded in a plurality of times, and the pre-reduced portion is remolded (reformed) in order to have a smooth and continuous outer surface. Form a part. In this way, in the remolding process, since the remolding process is performed step by step in a plurality of times, the remolding range in one remolding process can be reduced, and the molding load required for one remolding process can be reduced. It can be kept small (low).
In this case, in the subsequent remolding process, a part of the pre-reduced diameter portion is newly remolded, and the preceding remolding portion previously remolded before that is also included in the remolding mold. Since the molding is performed by pressing on the molding surface, it is possible to smoothly connect between the remolding portions and prevent the molding marks (indentations) from being left on the reduced diameter portions. Since the shaping of the preceding remolding portion is performed at the end of the subsequent remolding process, that is, at the bottom dead center of the remolding die, the preceding molding load is required for one remolding process. It is possible to smoothly perform the shaping of the remolding portion of the above and the molding of the subsequent remolding portion.

As a preferred embodiment of the method for manufacturing a can body of the present invention, each remolding process in the remolding step is performed while the processing diameter of the molding surface of each remolding die is gradually reduced, and the remolding process is performed. It is advisable to sequentially remold the pre-reduced portion from the lower side to the upper side each time.

Since each remolding process is performed in order from the lower side to the upper side of the preliminary reduced diameter portion, the roundness of the already reshaped lower side portion is increased at the time of remolding the upper side. Therefore, it is possible to prevent buckling that occurs in the body portion during each remolding process, and it is possible to stably form a reduced diameter portion (reduced diameter shape) that is smoothly connected to a wide region along the can axis direction.

As a preferred embodiment of the method for manufacturing a can body of the present invention, a guide surface that engages with the cylindrical outer surface of the body portion is provided at the tip end portion of the remolding mold, and a plurality of guide surfaces are provided in the remolding step. It is preferable that the outer surface of the body portion is restrained by the guide surface during the remolding process that is performed repeatedly.

By providing guide surfaces for each of the remolding dies, it is possible to align these guide surfaces with the lower side of the body that is not remolded, and it is repeated multiple times. In the remolding process, high-precision processing can be performed. In addition, by maintaining the state in which the outer surface of the body is restrained by the guide surface during each remolding process, deformation of the body in the radial direction is suppressed when a molding load is applied in the can axis direction. can. It is most desirable to restrain the entire circumference of the body, but even if it is partially restrained, deformation can be sufficiently suppressed.

According to the present invention, the manufacturing process of the can body can be shortened, and a reduced diameter shape smoothly connected to a wide region along the can axis direction can be stably formed.

It is a front view which made the right half of the container which used the bottle can manufactured by the manufacturing method of a bottle can which concerns on embodiment of this invention a cross section through a can shaft. Among the methods for manufacturing a bottle can of the present embodiment, it is a schematic view showing the steps from forming a cup to forming a cylinder in order, and the right half is a front view having a cross section passing through a can shaft. Of the steps after FIG. 2, it is a schematic view explaining the step of forming a reduced diameter shape including a shoulder portion, an inflection portion, and a reduced diameter portion, and the right half is a front view having a cross section passing through a can shaft. .. Of the steps after FIG. 3, it is a schematic view showing the steps from forming the small diameter cylinder portion to forming the curl portion in order, and the right half is a front view having a cross section passing through the can shaft. It is sectional drawing through the can shaft explaining the relationship between the diameter reduction die of the 1st diameter reduction processing in a preforming step, a cylinder body and an intermediate molded body. It is sectional drawing which passes through the can shaft which expanded the main part of the intermediate molded body in the preforming step, and (a) to (c) are the figure which showed the intermediate molded body which performed the diameter reduction step stepwise, respectively. It is sectional drawing which passes through the can shaft which expanded the main part of the intermediate molded body after a preforming process, and shows the relationship between the diameter reduction die of the 1st to 4th diameter reduction processing in a preforming process, and an intermediate molded body. It is a figure explaining. It is sectional drawing which passes through the can shaft which expanded the main part of the intermediate molded body in a remolding process, and is the figure explaining the relationship between the remolding die of the 1st remolding process in a remolding process, and an intermediate molded body. be. It is a figure which shows the state which pressed the remolding die against the intermediate molded body from the state shown in FIG. 8 in the 1st remolding process. It is sectional drawing which passes through the can shaft which expanded the main part of the intermediate molded body in a remolding process, and is the figure which shows the state which pressed the remolding die against the intermediate molded body in the second remolding process. It is sectional drawing which passes through the can shaft which expanded the main part of the intermediate molded body in a remolding process, and is the figure which shows the state which pressed the remolding die against the intermediate molded body in the 3rd remolding process. It is a front view of the bottle can manufacturing apparatus. It is sectional drawing which follows the AA line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The can body produced in the method for producing a can body according to the embodiment of the present invention is used for a can body such as a two-piece can or a bottle container in which the contents of a beverage or the like are filled and sealed. In the present embodiment, as shown in FIG. 1, a bottle can (can body) 101 used for the bottle container 301 will be described as an example.

FIG. 1 is a front view of a bottle container 301 including a bottle can 101 manufactured by the method for manufacturing a can body according to an embodiment of the present invention and a cap 201 attached to an open end portion 10a of the bottle can 101. It is a front view showing the right half as a cross section passing through the can shaft C. 2 to 4 are explanatory views showing each step of the manufacturing method of the bottle can 101 of the embodiment, and show the cross section of the main part of the cup 40, the cylinder 41, and the intermediate molded body 42 molded in each step. ing. Of these, FIG. 2 shows the process of forming the cup 40 to form the tubular body 41. Further, FIG. 3 shows a step of forming the shoulder portion 12, the inflection portion 14, and the diameter-reduced portion 13. FIG. 4 shows in order the steps from forming the mouth portion 15 above the diameter reduction portion 13 to manufacturing the bottle can 101.

The bottle can 101 is made of a thin plate metal such as aluminum or an aluminum alloy, and has a cylindrical body portion (wall) 10 and a disk-shaped bottom portion (bottom) 20 as shown in FIG. It is formed in the shape of a bottom cylinder.
As shown in FIG. 1, the body portion 10 and the bottom portion 20 are arranged coaxially with each other, and in the present embodiment, these common axes will be referred to as a can axis C for description. Further, among the directions along the can axis C (direction of the can axis C), the direction from the opening end 10a of the body portion 10 toward the bottom 20 side is downward, and the direction from the bottom 20 toward the opening end 10a is upward. In the following description, the vertical direction shall be determined in the same manner as the direction shown in FIG. Further, the direction orthogonal to the can axis C is referred to as a radial direction, and among the radial directions, the direction approaching the can axis C is the inner side (inner side) in the radial direction, and the direction away from the can axis C is the outer side in the radial direction (the direction away from the can axis C). Outside). Further, the direction of orbiting around the can axis C is defined as the circumferential direction.

As shown in FIG. 1, the body portion 10 has a cylindrical portion 11 formed in a cylindrical shape on the bottom portion 20 side and a shoulder portion 12 whose diameter is reduced so as to bend inward in the radial direction at the upper end of the cylindrical portion 11. And the diameter-reduced portion 13 that gradually reduces the diameter toward the upper side (opening end portion 10a side) in the can axis C direction, and the curved portion 14 that connects between the shoulder portion 12 and the diameter-reduced portion 13. A mouth portion 15 connected to the upper end of the reduced diameter portion 13 is provided. As shown in FIG. 1, assuming that the angle (inclination angle) formed by the reduced diameter portion 13 and the can shaft C is α, the inclined angle α is provided to be, for example, 6 ° or more and 24 ° or less, and the reduced diameter portion 13 is provided. It is formed in a shape standing in the can axis C direction. The cylindrical portion 11, the shoulder portion 12, the inflection portion 14, and the diameter-reduced portion 13 each form an annular shape extending over the entire circumference of the body portion 10 in the circumferential direction.

Further, the cylindrical portion 11, the shoulder portion 12, the inflection portion 14, and the reduced diameter portion 13 are smoothly connected to each other, and are smoothly connected to each other without forming a step. ing. Specifically, in the vertical cross-sectional view shown in FIG. 1, the shoulder portion 12 is formed in a convex curved surface shape that is convex toward the outside (outside in the radial direction) and the upper side of the body portion 10. The lower end of the 12 is provided in contact with the upper end of the cylindrical portion 11, and the cylindrical portion 11 is provided as a tangent to the shoulder portion 12 and is provided in a straight line downward. The inflection portion 14 is formed in a concave curved surface shape that is concave toward the inside (inside in the radial direction) and downward of the body portion 10, and the lower end of the inflection portion 14 and the upper end of the shoulder portion 12 are in contact with each other. The upper end of the shoulder portion 12 and the lower end of the inflection portion 14 are formed so as to have a common tangent line. Further, the upper end of the inflection portion 14 and the lower end of the reduced diameter portion 13 are provided in contact with each other, and the reduced diameter portion 13 is a tangent line of the inflection portion 14.

Further, the mouth portion 15 arranged at the upper portion of the body portion 10 includes a large diameter portion 31 whose diameter is once expanded at the upper end of the reduced diameter portion 13 and a small diameter portion 32 whose diameter is reduced again at the upper end of the large diameter portion 31. It has a curl portion 33 formed at the open end portion 10a at the upper end of the small diameter portion 32. As described above, the mouth portion 15 is opened to the outside by the opening end portion 10a, and the contents such as beverages are filled inside the bottle can 101 through the mouth portion 15. Further, as shown in FIG. 1, by attaching the cap 201 to the mouth portion 15, the contents filled in the inside of the bottle can 101 are sealed.

The bottom portion 20 of the bottle can 101 is located on the can shaft C, and has a dome portion 21 formed so as to bulge upward (inside the body portion 10) and an outer peripheral edge of the dome portion 21. A heel portion 22 for connecting the portion and the lower end portion of the body portion 10 is provided. Further, the connecting portion between the dome portion 21 and the heel portion 22 has a ground contact surface (a posture in which the open end portion 10a of the body portion 10 faces upward as shown in FIG. 1) so that the bottle can 101 is in an upright posture. The ground contact portion 23 is in contact with the ground contact surface when mounted on the mounting surface). The ground contact portion 23 projects downward at the bottom portion 20 and forms an annular shape extending along the circumferential direction.

To give an example of other dimensions of the bottle can 101 configured as described above, the original plate thickness of the bottle can 101 before molding is 0.250 mm to 0.500 mm. Further, in a vertical cross-sectional view of the bottle can 101 shown in FIG. 1 through the can shaft C, the outer diameter Db of the cylindrical portion 11 to be a product is 52 mm to 68 mm, and the radius of curvature R11 of the shoulder portion 12 (on the outer surface of the shoulder portion 12). The radius of curvature) is 12 mm to 30 mm, and the radius of curvature R12 of the curved portion 14 (radius of curvature on the outer surface of the curved portion 14) is 10 mm to 24 mm. The outer diameter Ds1 (contact point between the reduced diameter portion 13 and the inflection portion 14) at the lower end of the reduced diameter portion 13 is set to be within the range of, for example, 30 mm to 45 mm, and the outer diameter Ds2 (reduced diameter) at the upper end of the reduced diameter portion 13 is set. The contact point between the portion 13 and the mouth portion 15) is, for example, within the range of 22 mm to 30 mm. However, the above dimensions are not limited to the above numerical range.

In the case of the bottle can 101 of the first embodiment shown in FIG. 1, the outer diameter Db of the cylindrical portion 11 is 66 mm, the radius of curvature R11 of the shoulder portion 12 is 24 mm, the radius of curvature R12 of the curved portion 14 is 18 mm, and the reduced diameter portion. The inclination angle α of 13 is 10 °.

As described above, in order to manufacture the bottle can 101 having the reduced diameter portion 13, first, an aluminum plate material such as an aluminum alloy is punched out and drawn to have a relatively large diameter as shown in FIG. 2A. Mold the shallow cup 40. Then, drawing and ironing (DI processing) are performed again on the cup 40 to form a bottomed cylindrical cylinder 41 having a predetermined height as shown in FIG. 2 (b), and the upper end thereof is trimmed. Cut by. By this DI processing, the bottom portion of the tubular body 41 is formed into the shape of the bottom portion 20 as the final bottle can 101.

Then, for example, the bottle can 101 is manufactured by the bottle can manufacturing apparatus 501 shown in FIGS. 12 and 13. The bottle can manufacturing apparatus 501 will be described below. The bottle can manufacturing apparatus 501 is for processing the cylindrical body 41 formed as described above into a bottle can 101 having a final shape, and the shape of the can changes according to the progress of processing. However, in the following, when the shape of the bottomed cylindrical can (the cylinder having the body portion in the present invention) between the cylinder 41 and the bottle can 101 is not particularly limited, the intermediate molded body 42 is used. explain. Further, in the following, the body portion and the bottom portion of the intermediate molded body 42 will be described using the same reference numerals as the body portion 10 and the bottom portion 20 of the bottle can 101.

The bottle can manufacturing apparatus 501 includes a work holding portion 511 that holds a plurality of intermediate molded bodies 42 in a horizontal arrangement in the can axis C direction, and a plurality of molding tools that perform various molding processes on the intermediate molded bodies 42. It includes a tool holding unit 513 that holds 512, and a driving unit 514 that drives both holding units 511 and 513. The work holding side of the work holding portion 511 that holds the intermediate molded body 42 and the tool holding side of the tool holding portion 513 that holds the molding tool 512 are arranged so as to face each other.

As shown in FIG. 13, the work holding portion 511 has a plurality of holding devices 517 for holding the intermediate molded body 42 along the circumferential direction on the surface of the disk 516 supported by the support shaft 515 facing the tool holding portion 513. It is configured to be arranged in a ring. The disk 516 is intermittently rotated around the support shaft 515 by the drive unit 514, so that the bottom portion of the intermediate molded body 42 supplied from the supply unit 518 via the supply side star wheel 519 is set to the holding device 517 by 1. Each piece is held and conveyed in the circumferential direction of the disk 516. The intermediate molded body 42 is molded by each molding tool 512 of the tool holding portion 513 during transportation by the disk 516, and then sequentially discharged to the discharge unit 611 as a molded bottle can 101 via the discharge side star wheel 601. ..

In the tool holding portion 513, a plurality of various molding tools 512 are arranged in an annular shape along the circumferential direction on the surface of the disk 613 supported by the support shaft 612 facing the work holding portion 511, and the disk 613 is supported by the drive unit 514. It is configured to move forward and backward in the axial direction of the shaft 612. The support shaft 612 is provided coaxially with the support shaft 515 inside the support shaft 515.

The tool holding portion 513 includes a plurality of diameter reduction dies for reducing the diameter (neck-in processing) of the opening of the intermediate molded body 42, a curl portion forming tool for forming the curl portion 33, and the like. , A plurality of molding tools 512 for performing machining according to each machining step are provided. These molding tools 512 are arranged in an annular shape on the disk 613 in the order of processes so as to be arranged in the circumferential direction.

The intermittent rotation stop position of the work holding portion 511 (disk 516) centered on the axis of the support shaft 515 is such that the can shaft C of each intermediate molded body 42 with the opening facing the tool holding portion 513 is molded. It is set to match the central axis of the tool 512. Then, by the intermittent rotation of the disk 516 by the drive unit 514, each intermediate molded body 42 is rotationally moved to a position facing each molding tool 512 for the next process, and the next step of processing is performed.

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 molding tool 512 performs processing according to each process on the intermediate molded body 42, and both holding portions 511. , 513 are separated from each other, and the work holding portion 511 is rotationally moved so that the molding tool 512 of the next step faces each intermediate molded body 42. In this way, the two holding portions 511, 513 are processed in close proximity to each other, and the operations of separating and rotating are repeated, so that the intermediate molded body 42 has a shoulder portion 12, a curved portion 14, a reduced diameter portion 13, and a mouth. The portions 15 are sequentially formed to form the bottle can 101.

Next, the method of manufacturing the bottle can 101 using the bottle can manufacturing apparatus 501 will be described in detail in the order of processes.
A plurality of forming tools arranged in the circumferential direction of the tool holding portion 513 with respect to the upper end portion of the tubular body 41 formed to the state shown in FIG. 2 (b) by drawing and ironing (DI forming) a thin plate such as an aluminum alloy. While sequentially using the 512, the molding tool 512 is moved along the can axis C direction to perform a die-necking process. As a result, as shown in FIG. 3 (a), the shoulder portion 12 and the inflection portion 14 are formed in order by reducing the diameter of the upper portion from the middle position in the height direction of the tubular body 41, and then in FIG. 3 (c). As shown, a tapered diameter-reduced portion 13 is formed in which the upper portion of the inflection portion 14 is gradually reduced in diameter toward the upper side.

Of these, in the reduced diameter portion forming step of forming the reduced diameter portion 13, as shown in FIG. 5, the bottom portion 20 of the body portion 10 of the intermediate molded body 42 in which the shoulder portion 12 and the curved portion 14 are formed is formed. The portions 44 and 45 above the lower portion 43 (cylindrical portion 11, shoulder portion 12, curved portion 13) arranged on the side are processed. Then, the diameter of the planned diameter reduction portion 44 located between the lower portion 43 and the upper portion 45 arranged on the opening end portion 42a side was gradually reduced from the lower side to the upper side along the can axis C direction. That is, a reduced diameter portion 13 having a gradually smaller diameter is formed, and a cylindrical upper portion 17 having a smaller diameter than the upper portion 45 is formed on the upper portion 45 arranged adjacent to the reduced diameter portion 13. The shape shown by the alternate long and short dash line in FIG. 5 is the intermediate molded body 42 in which the reduced diameter portion 13 and the upper portion 17 of the cylinder are formed.

The reduced diameter portion forming step for forming such a reduced diameter portion 13 includes a preforming step and a remolding step, and the remolding step is carried out after the preforming step. In the pre-formation step, as shown in FIG. 3 (b), a pre-diameter portion 16 having an uneven surface whose diameter is gradually reduced from the lower side to the upper side is formed. Then, in the remolding step, the pre-diameter portion 16 formed in the pre-forming step is remolded, and as shown in FIG. 3 (c), shrinkage having a tapered smooth continuous outer surface from the lower side to the upper side. The diameter portion 13 is formed.

[Preliminary formation process]
In the preforming step, the upper portion 45 of the intermediate molded body 42 is processed in order to process the planned diameter reduction portion 44 (long region along the can axis C direction) in a wide region connecting between the lower portion 43 and the upper portion 45 of the body portion 10. And, a plurality of diameter reduction dies (dinecking dies) having different processing diameters are fitted to the outer surface of the planned diameter reduction portion 44 in order from the side having the largest processing diameter, and the diameter reduction processing is performed a plurality of times. In the preformation step of the present embodiment, as shown in FIG. 7 and the like, the amount of one processing in each diameter reduction processing (indicated by the reference numerals g11 to g14 in FIG. 7) is increased, and the processing is intentionally made at intervals. do. As a result, as shown in FIGS. 7 and 8, local diameter reduction portions 46a to 46i are formed in which the diameter is gradually reduced from the lower side to the upper side in each diameter reduction processing, and the preliminary diameter reduction having an uneven surface is formed. The portion 16 is formed. As described above, in the pre-molding step, it is allowed that molding marks (concave-convex surface) due to the diameter-reducing process are formed on the pre-diameter-reduced portion 16.

In each diameter reduction process performed a plurality of times, the diameter reduction amount (machining amount) is calculated as follows. As shown in FIG. 7 with an enlarged view of a main part of the preliminary diameter reduction portion 16, the diameter reduction amount g11 of the first diameter reduction processing is the diameter reduction planned portion 44 of the intermediate molded body 42 before the first diameter reduction processing. It is the difference between the minimum diameter of the outer surface of (and the upper portion 45) and the minimum diameter of the molding surface 720a of the diameter reduction die 701A used for the first time. Further, the diameter reduction amount g12 of the second diameter reduction process is the minimum diameter of the molding surface 720a of the diameter reduction die 701A used in the first time and the molding surface 720b of the diameter reduction die 701B used in the second time. It is the difference between the minimum diameter and. The diameter reduction amounts g13, g14, etc. of each diameter reduction process after the third time are calculated in the same manner as the second diameter reduction amount g12, and the minimum diameter of the molding surface of the immediately preceding diameter reduction die and the respective reductions. This is the difference from the minimum diameter of the molding surface of the diameter reduction die used in diameter processing. It should be noted that each diameter reduction is based on the diameter reduction amounts g11 to g14 and the like (in FIG. 7, only the diameter reduction amounts g11 to g14 from the first to the fourth times are shown) and the angle α of the diameter reduction portion 13 to be molded. The amount of shift of the mold in the can axis C direction, such as s11 to s14, can be calculated.

In the pre-formation step of the present embodiment, the pre-diameter portion 16 having the local diameter-reduced portions 46a to 46i is formed as shown in FIG. 8 through a total of nine diameter-reducing processes. The number of times of diameter reduction processing is not limited to 9, and is appropriately adjusted according to the size of the processing region (planned diameter reduction portion 44) and the like. Hereinafter, in the description of the present embodiment, the description of the 4th to 9th diameter reduction processing is omitted from the 9 times diameter reduction processing performed in the preforming step, and the 1st to 3rd diameter reduction processing is omitted. Will be explained as an example.

Specifically, as shown in FIGS. 5 and 6 (a) to 6 (c), the respective diameter reduction dies 701A to 701C used for the first to third diameter reduction processing are each of the intermediate molded bodies 42. It is configured to include inner dies 71A to 71C arranged inside and outer dies 72A to 72C arranged outside the intermediate molded body 42 and having annular forming surfaces 720a to 720c. The central axis of each inner die 71A to 71C of each diameter reduction mold 701A to 701C and the central axis of each outer die 72A to 72C are arranged coaxially with the can shaft C, and each of the inner dies 71A to 71C. Cylindrical gaps 73a to 73c into which the open end portion 42a of the intermediate molded body 42 is pushed are formed between the outer dies 72A to 72C.

In each diameter reduction processing, as shown in FIGS. 6A to 6C, the intermediate molded body 42 and the diameter reduction dies 701A to 701C are relatively close to each other in the can axis C direction (relative movement). Between the first inner die 71A and the first outer die 72A (FIG. 6 (a)), between the second inner die 71B and the second outer die 72B (FIG. 6 (b)), the third inner die. The upper portion 45 of the intermediate molded body 42 and the planned diameter reduction portion 44 are sequentially inserted between the 71C and the third outer die 72C (FIG. 6 (c)) to shrink from the open end portion 42a of the intermediate molded body 42. The entire area up to the planned diameter portion 44 (the upper portion 45 and the planned diameter reduction portion 44) is reduced in diameter. Further, as described above, in each diameter reduction processing, the processing diameters of the diameter reduction dies 701A to 701C, specifically, the processing diameters of the molding surfaces 720a to 720c of the outer dies 72A to 72C are gradually reduced. While doing so, it is divided into a plurality of times (in this case, 3 times, 9 times in total), and each time the diameter reduction processing is performed, the local diameter reduction portions 46a to 46c which become a part of the preliminary diameter reduction portion 16 are formed. Molding is performed while shifting the position from the lower side to the upper side of the planned diameter reduction portion 44.

The tip portions 740a to 740c of the outer dies 72A to 72C are formed with annular guide surfaces 741a to 741c that engage with the outer surface of the cylindrical portion 11 formed in the lower portion 43 of the intermediate molded body 42. By engaging the guide surfaces 741a to 741c with the outer surface of the cylindrical portion 11, the respective diameter reduction dies 701A to 701C and the intermediate molded body 42 are aligned with each other.

The molded surfaces 720a to 720c are formed on the inner peripheral surfaces of the outer dies 72A to 72C, and project radially inward and downward as shown in the vertical cross-sectional views of FIGS. 6A to 6C. Convex curved surface-shaped molded convex curved surfaces 721a to 721c and cylindrical linear molded surfaces 722a to 722c continuous at the upper ends of the molded convex curved surfaces 721a to 721c are formed over the entire circumference in the circumferential direction. Further, the linear forming surfaces 722a to 722c are smoothly connected to the upper ends of the respective forming convex curved surfaces 721a to 721c, and are linear on the innermost side (inside in the radial direction) of the respective forming surfaces 720a to 720c and parallel to the can axis C direction. Is formed in.

To give an example of various dimensions of the molded surfaces 720a to 720c of the diameter reduction dies 701A to 701C in the present embodiment, the radius of curvature R21 of the molded convex curved surfaces 721a to 721c is 2.0 mm to 10.0 mm. Further, the intervals (one-sided width) g11 to g13 of the linearly formed surfaces 722a to 722c are provided at 0.25 mm or more and 1.0 mm or less (diameter difference of 0.5 mm or more and 2.0 mm or less).

In addition, on the tip end side of each outer die 72A to 72C arranged adjacent to the lower end of the molding surface 720a to 720c, a tapered tip flank surface 723a to 723c continuous with the lower end of the molding convex curved surface 721a to 721c is formed. There is. The tip flanks 723a to 723c are smoothly connected to the lower ends of the molded convex curved surfaces 721a to 721c, and are formed so as to be separated from the inflection portion 14 and the shoulder portion 12 toward the lower side. As described above, the tip portions 740a to 740c of the outer dies 72A to 72C are provided with guide surfaces 741a to 741c that engage with the cylindrical portion 11.
On the other hand, the proximal end side of the outer dies 72A to 72C arranged adjacent to the upper ends of the forming surfaces 720a to 720c is provided with a diameter reduced inward in the radial direction from the linear forming surfaces 722a to 722c. 724a to 724c are formed.

In the preforming step, first, as shown in FIG. 5, the intermediate molded body 42 and the diameter-reducing die are placed in a state where the diameter-reducing die 701A having the largest processing diameter is arranged above the intermediate molded body 42. As shown in FIG. 6A, the upper portion 45 of the intermediate molded body 42 and the planned diameter reduction portion 44 are moved toward the first inner die 71A while the mold 701A and the mold 701A are relatively close to each other (relatively moved) in the can axis C direction. It is performed by entering the gap 73a between the first outer die 72A and the first outer die 72A. In the present embodiment, the diameter reduction die 701A is moved closer (advanced) to the intermediate molded body 42 in the can axis C direction to reduce the diameter. In the first diameter reduction processing by the diameter reduction die 701A, the entire region from the opening end portion 42a of the intermediate molded body 42 to the lower end of the diameter reduction planned portion 44 (the entire upper portion 45 and the diameter reduction planned portion 44) is covered. Process.

When the diameter reduction die 701A is brought close to the intermediate molded body 42, the open end portion 42a of the intermediate molded body 42 comes into contact with the intermediate position of the molded convex curved surface 721a of the molded surface 720a, and the linear molded surface 722a is contacted from the molded convex curved surface 721a. Are pressed in this order and molded along the molding surface 720a. As a result, the region from the opening end portion 42a to the lower end of the diameter reduction planned portion 44 is sequentially reduced in diameter in the radial direction. Then, as shown in FIG. 6A, a locally reduced diameter portion 46a of the intermediate molded body 42 is formed on the lower side of the planned diameter reduction portion 44.

After the first diameter reduction processing by the diameter reduction die 701A, the diameter reduction die 701A is separated (retracted) from the intermediate molded body 42 in the can axis C direction. As a result, the intermediate molded body 42 is separated from the first inner die 71A and the first outer die 72A, and is returned to the original position (lowering preparation position, standby position).

After forming the local diameter reduction portion 46a by the first diameter reduction processing with the diameter reduction mold 701A, the second diameter reduction mold 701B has a smaller processing diameter by one side width g12 than the diameter reduction mold 701A. Perform diameter reduction processing. As shown in FIG. 6B, the opening end portion 42a of the intermediate molded body 42 is made to enter the gap 73b between the second inner die 71B and the second outer die 72B of the diameter reduction die 701B, and the forming convex surface is formed. A new locally reduced diameter portion 46b is formed on the upper side of the first (immediately preceding) locally reduced diameter portion 46a formed in advance by the curved surface 721b and the linear forming surface 722b.

Subsequently, the third diameter reduction is performed by the diameter reduction die 701C whose processing diameter is smaller by the width g13 on one side than the diameter reduction die 701B. As shown in FIG. 6 (c), a new locally reduced diameter portion is formed on the upper side of the second (immediately preceding) locally reduced diameter portion 46b previously molded by the molded convex curved surface 721c and the linear molding surface 722c. Mold 46c. Hereinafter, although not shown, the diameter-reducing dies are sequentially subjected to the fourth to ninth diameter-reducing processes using the diameter-reducing dies having the same configuration as the diameter-reducing dies 701A to 701C. Molding of the mold New locally reduced diameter portions 46d to 46i are formed above the locally reduced diameter portion formed immediately before by the convex curved surface and the linear forming surface. In this way, by forming the locally reduced diameter portion formed by each diameter reducing die while shifting the position from the lower side to the upper side, as shown in FIGS. 7 and 8, each locally reduced diameter portion is formed. Preliminary diameter-reduced portions 16 are formed in which 46a to 46i are formed at intervals from the lower side to the upper side. Further, a cylindrical upper portion 17 having a small diameter is formed above the preliminary reduced diameter portion 16 formed in this way.

[Remolding process]
Next, in the remolding step, the pre-reduced portion 16 in which the molding marks formed in the pre-molding step remain is subjected to the remolding process in a plurality of times, and the pre-reduced portion 16 is remolded in order from the lower side to the upper side. It is molded (reformed) to form a reduced diameter portion 13 having a smoothly continuous outer surface. Similar to the diameter reduction dies 701A to 701C shown in FIG. Is used to fit in order from the side with the largest processing diameter, and remolding is performed multiple times. The inner die is not essential in the remolding step, and the remolding process may be performed without using the inner die. In the remolding step of the present embodiment, after a total of three remolding processes, as shown in FIGS. 3C and 11, the diameter of the taper is gradually reduced from the lower side to the upper side. The diameter portion 13 is formed. The number of remolding processes is not limited to three, and is appropriately adjusted according to the size of the processing area (planned diameter reduction portion 44, preliminary diameter reduction portion 16) and the like.

Specifically, the remolding dies 801A to 801C used for the three remolding processes are arranged on the inner dies 81A to 81C arranged inside the intermediate molded body 42 and on the outside of the intermediate molded body 42, respectively. The outer dies 82A to 82C having annular molding surfaces 820a to 820c are provided. The central axis of each inner die 81A to 81C of each remolding die 801A to 801C and the central axis of each outer die 82A to 82C are arranged coaxially with the can shaft C, and each of the inner dies 81A to 81C. Cylindrical gaps 83a to 83c are formed between the outer dies 82A to 82C. Then, in each remolding process, as shown in FIGS. 8 to 11, the intermediate molded body 42 and the remolding dies 801A to 801C are relatively close to each other (relatively moved) in the can axis C direction. This is performed by sequentially pressing the molding surfaces 820a to 820c of the outer dies 82A to 82C of the remolding dies 801A to 801C against the outer surface of the preliminary diameter reduction portion 16. Further, as described above, in each remolding process, the processing diameters of the remolding dies 801A to 801C, specifically, the processing diameters of the forming surfaces 820a to 820c of the outer dies 82A to 82C are gradually reduced. While doing this, divide it into multiple times (in this case, 3 times). In this way, each time the remolding process is performed, the remolding dies 801A to 801C shift the positions of the preliminary reduced diameter portions 16 from the lower side to the upper side, and each local reduced diameter portion 46a to A region wider than the interval of 46i is sequentially remolded by crushing it downward in the can axis C direction.

Further, on the respective tip portions 840a to 840c of the outer dies 82A to 82C, annular guide surfaces 841a to 841c that engage with the outer surface of the cylindrical portion 11 formed in the lower portion 43 of the intermediate molded body 42 are formed. ing. In each remolding process, by engaging the guide surfaces 841a to 841c with the outer surface of the cylindrical portion 11, the remolding dies 801A to 801C are aligned with the intermediate molded body 42, and each of them is aligned. The outer surface of the cylindrical portion 11 is constrained by the guide surfaces 841a to 841c during the remolding process.

The molded surfaces 820a to 820c are formed on the inner peripheral surfaces of the outer dies 82A to 82C, and as shown in the vertical cross-sectional view of FIGS. 8 to 11, the tapered shape is gradually reduced in diameter from the lower side to the upper side. The tapered surfaces 821a to 821c, the convex curved lower convex curved surfaces 822a to 822c continuous at the lower ends of the tapered surfaces 821a to 821c, and the convex curved upper convex curved surface 823a continuous at the upper ends of the tapered surfaces 821a to 821c. ~ 823c is formed over the entire circumference in the circumferential direction. The tapered surfaces 821a to 821c are formed in a tapered shape along the reduced diameter portion 13. Further, the lower convex curved surfaces 822a to 822c are smoothly connected to the lower ends of the tapered surfaces 821a to 821c, and the radius of curvature R22 is formed to be the same as or smaller than the radius of curvature R12 of the inflection portion 14.

On the tip end side of each outer die 82A to 82C arranged adjacent to the lower end of the molded surface 820a to 820c, a tapered tip flank surface 824a to 824c continuous with the lower end of the lower convex curved surface 822a to 822c is formed. There is. The tip flanks 824a to 824c are smoothly connected to the lower ends of the lower convex curved surfaces 822a to 822c, and are formed so as to be separated from the inflection portion 14 and the shoulder portion 12 toward the lower side. As described above, the tip portions 840a to 840c of the outer dies 82A to 82C are provided with guide surfaces 841a to 841c that engage with the cylindrical portion 11.
On the other hand, on the base end side of the outer dies 82A to 82C arranged adjacent to the upper ends of the molded surfaces 820a to 820c, continuous cylindrical straight cylindrical surfaces 825a to 825c are formed on the upper ends of the upper convex curved surfaces 823a to 823c. There is. The straight cylindrical surfaces 825a to 825c are smoothly connected to the upper ends of the upper convex curved surfaces 823a to 823c, and are formed in a straight line parallel to the can axis C direction.

To give an example of various dimensions of the molding surfaces 820a to 820c of the remolding dies 801A to 801C in the present embodiment, the inclination angle β of the tapered surfaces 821a to 821c (the angle formed by the tapered surfaces 821a to 821c and the can shaft C). , FIG. 8) is set to a size of −2 ° or more and 0 ° or less with respect to the inclination angle α of the reduced diameter portion 13. That is, the inclination angle β of the tapered surfaces 821a to 821c is the same angle (β = α) as the inclination angle α of the reduced diameter portion 13 to be molded, or a slightly smaller angle (α-2 ° <β <α). ) Is formed. The radius of curvature R22 of the lower convex curved surfaces 822a to 822c is 2.0 mm to 20.0 mm, and the radius of curvature R23 of the upper convex curved surfaces 823a to 823c is 2.0 mm to 40.0 mm. Further, the intervals (one-sided width) g21 to g22 of the linear cylindrical surfaces 825a to 825c are provided at 1.0 mm or more and 10.0 mm or less (diameter difference of 2.0 mm or more and 20.0 mm or less).

In the remolding step, first, the remolding die 801A having the largest processing diameter is arranged at a distance above the intermediate molded body 42, and then, as shown in FIG. 8, the intermediate molded body 42 and the remolding die 42 are arranged. The mold 801A is relatively close to (relatively moved) in the can axis C direction, and as shown in FIG. 9, the outer surface on the lower side of the preliminary diameter reduction portion 16 is pressed by the molding surface 820a of the first outer die 82A. Do it by. In this embodiment, the remolding die 801A is moved closer to (advanced) in the can axis C direction with respect to the intermediate molded body 42, and is remolded.

When the remolding die 801A is brought close to the intermediate molded body 42, the guide surface 841a provided at the tip portion 840a first engages with the outer surface of the cylindrical portion 11, and the remolding die 801A and the intermediate molded body are engaged with each other. 42 is aligned with. Subsequently, the outer surface of the locally reduced diameter portions 46a to 46c on the lower side of the preliminary reduced diameter portion 16 comes into contact with and pressed against the molding surface 820a of the first outer die 82A. A region wider than the distance between the individual locally reduced diameter portions 46a to 46c is pressed downward in the can axis C direction by the molding surface 820a, so that the convex surface formed between the locally reduced diameter portions 46a to 46c is pushed. It is crushed and disappears, and is remolded into a shape along the molding surface 820a. As a result, a tapered remolding portion 47a smoothly connected to the upper end of the inflection portion 14 is formed on the lower side of the preliminary diameter reduction portion 16. Further, during the remolding process by the remolding die 801A, the guide surface 841a engages with the outer surface of the cylindrical portion 11 and the state of restraining the outer surface of the cylindrical portion 11 is maintained. As a result, when a molding load is applied in the can axis C direction during the remolding process, the deformation of the cylindrical portion 11 in the radial direction can be suppressed.

After the first remolding process by the remolding die 801A, the remolding die 801A is separated (retracted) from the intermediate molded body 42 in the can axis C direction. As a result, the intermediate molded body 42 is separated from the first inner die 81A and the first outer die 82A, and is returned to the original position (lowering preparation position, standby position).

After the first remolding process by the remolding die 801A, the second remolding process is performed by the remolding die 801B whose processing diameter is smaller by one side width g21 than the remolding die 801A. In the second remolding process, as shown in FIG. 10, the remolding die 801B is brought close to the intermediate molded body 42, and the outer surface of the locally reduced diameter portions 46c to 46f of the intermediate portion of the preliminary reduced diameter portion 16 is formed. The molding surface 820b of the second outer die 82B is pressed against the molding surface 820b to remold. As a result, a new remolding portion 47b is molded on the upper side of the first (immediately preceding) remolding portion 47a that was previously molded.

Also in the remolding die 801B, the guide surface 841b provided at the tip portion 840b was engaged with the outer surface of the cylindrical portion 11 in advance, and the remolding die 801B and the intermediate molded body 42 were aligned. After that, the outer surface of the locally reduced diameter portion 46c to 46f of the intermediate portion of the preliminary reduced diameter portion 16 comes into contact with the molding surface 820b of the second outer die 82B and is pressed against the molded surface 820b. Also in the second remolding step, the guide surface 841b of the remolding die 801B engages with the outer surface of the cylindrical portion 11, and the state in which the outer surface of the cylindrical portion 11 is restrained is maintained. As a result, when a molding load is applied in the can axis C direction during the remolding process, the deformation of the cylindrical portion 11 in the radial direction can be suppressed.

Further, in the second remolding process (following remolding process), a part of the preliminary diameter reduction portion 16 is newly remolded to form the remolding portion 47a, and the remolding portion is preceded before that. The preceding remolding portion 47a is also shaped by pressing with the molding surface 820b of the second outer die 82B. As shown in FIG. 10, the second outer die 82B for forming the new remolding portion 47b extends to a position where the lower side of the tapered surface 821b constituting the molding surface 820b overlaps with the preceding remolding portion 47a. It is provided. As a result, in the second remolding process, the convex surface newly formed between the locally reduced diameter portions 46c to 46f is crushed on the upper side of the tapered surface 821b to form the remolding portion 47a, and the taper is formed. The preceding remolding portion 47a is shaped on the lower side of the surface 821b. As described above, in the second remolding process, the tapered surface 821b extending to the position overlapping with the preceding remolding portion 47a is used to newly remold from the preceding remolding portion 47a. By continuously processing up to the remolding portion 47b, a new remolding portion 47b is continuously formed on the preceding remolding portion 47a. As a result, the succeeding remolding portion 47b is smoothly connected to the preceding remolding portion 47a without creating an unregenerated processed region between the preceding remolding portion 47a and the succeeding remolding portion 47b. To.

Subsequently, after the second remolding process, the third remolding process is performed by the remolding die 801C having a processing diameter smaller than that of the remolding die 801B by one side width g22.
In the third remolding process, as shown in FIG. 11, the remolding die 801C is brought close to the intermediate molded body 42, and the outer surface of the locally reduced diameter portions 46f to 46i on the upper side of the preliminary reduced diameter portion 16 is formed. The molding surface 820c of the third outer die 82C is pressed and remolded. As a result, a new remolding portion 47c is molded on the upper side of the second (immediately preceding) remolding portion 47b that was previously molded.

Also in the remolding die 801C, the guide surface 841c provided at the tip portion 840c was engaged with the outer surface of the cylindrical portion 11 in advance, and the remolding die 801C and the intermediate molded body 42 were aligned. After that, the outer surface of the locally reduced diameter portions 46f to 46i on the upper side of the preliminary reduced diameter portion 16 comes into contact with the molding surface 820c of the third outer die 82C and is pressed against the molded surface 820c. Even in the third remolding step, the guide surface 841c of the remolding die 801C is engaged with the outer surface of the cylindrical portion 11, and the state in which the outer surface of the cylindrical portion 11 is restrained is maintained. As a result, when a molding load is applied in the can axis C direction during the remolding process, the deformation of the cylindrical portion 11 in the radial direction can be suppressed.

Further, in the third remolding process (following remolding process), a part of the preliminary diameter reduction portion 16 is newly remolded to form the remolded portion 47c as in the second remolding process. At the same time, the preceding remolding portion 47b, which was previously remolded before that, is also shaped by pressing with the molding surface 820c of the third outer die 82C. As shown in FIG. 11, the third outer die 82C used for the third remolding process is provided so as to extend to a position where the lower side of the tapered surface 821c constituting the molding surface 820c overlaps with the preceding remolding portion 47b. Has been done. As a result, in the third remolding process, the convex surface newly formed between the locally reduced diameter portions 46f to 46i is crushed on the upper side of the tapered surface 821c to form the remolding portion 47c, and the taper is formed. The preceding remolding portion 47b is shaped on the lower side of the surface 821c. As described above, in the third remolding process, the tapered surface 821c extending to the position overlapping with the preceding remolding portion 47b is used to newly remold from the preceding remolding portion 47b. By continuously processing up to the remolding portion 47c, a new remolding portion 47c is continuously formed on the preceding remolding portion 47b. As a result, the succeeding remolding portion 47c is smoothly connected to the preceding remolding portion 47b without creating an unregenerated processed region between the preceding remolding portion 47b and the succeeding remolding portion 47c. To.

As described above, in the remolding step, by performing the remolding process a plurality of times (three times in this embodiment), the pre-diameter portions 16 are sequentially subjected to the remolding dies 801A to 801C from the lower side to the upper part. A region wider than the individual spacing of the locally reduced diameter portions 46a to 46i is remolded while shifting the position toward the side. As a result, as shown in FIG. 11, the uneven surface of the preliminary reduced diameter portion 16 disappears, and the reduced diameter portion 13 having a smoothly continuous outer surface is formed from the lower side to the upper side.

Further, as shown in FIG. 4A, the cylinder upper portion 17 of the intermediate molded body 42 formed in this way has a larger diameter than the upper end of the reduced diameter portion 13 by expanding the diameter of the cylindrical upper portion 17. By forming the diameter portion 31 and reducing the diameter again after forming the large diameter portion 31, a small diameter portion 32 that gradually shrinks in the upward direction is formed, and a cylinder extending above the small diameter portion 32 is formed. A small diameter cylinder portion 34 having a shape is formed. Finally, the small-diameter cylinder portion 34 is curled to form the curl portion 33, and as shown in FIG. 4 (b), the bottle can 101 having the mouth portion 15 is manufactured.

The inside of the bottle can 101 manufactured in this manner is filled with contents such as beverages, the cap 201 is wrapped around the mouth portion 15, and the inside of the bottle can 301 is sealed.

According to the method for manufacturing a can body according to the present embodiment described above, by performing the reduced diameter portion forming step separately for the preforming step and the remolding step, it is smoothly connected to a wide area along the can axis C direction. The reduced diameter portion 13 can be stably formed. Further, in the pre-molding step, since it is allowed to form molding marks (concave and convex surfaces) on the pre-diameter reduced portion 16, the amount of one machining in each diameter-reduced machining can be increased, and it is wide along the can axis C direction. When forming a reduced diameter shape in the region, it is possible to shorten the manufacturing process of the can body. Further, in the remolding step, since the pre-reduced portion 16 in which the molding marks remain is subjected to the remolding process in a plurality of times, the remolding range in one remolding process can be reduced, and the remolding process can be performed once. The required molding load can be kept small (low).

Further, since each remolding process is performed in order from the lower side to the upper side of the preliminary diameter reduction portion 16, the roundness of the already reshaped lower side portion is increased at the time of remolding the upper side. Therefore, it is possible to prevent buckling that occurs in the body portion 10 during each remolding process, and it is possible to stably form a reduced diameter portion (reduced diameter shape) 13 that is smoothly connected to a wide region along the can axis C direction.
In addition, each remolding step in the remolding step may be performed in order from the upper side to the lower side of the preliminary diameter reduction portion 16. In this case, each remolding step performed a plurality of times is performed while gradually increasing the processing diameter of the molding surface of each remolding die.

Further, in the present embodiment, in the subsequent remolding process performed in the second and third times, a part of the preliminary diameter reduction portion 16 is newly remolded, and the preformed portion is remolded prior to that. Since the preceding remolding portions 47a and 47b of the first and second remolding portions are also shaped, the remolding portions 47a to 47c can be smoothly connected, and molding marks (indentations) are left on the reduced diameter portion 13. Can be prevented. Since the preceding remolding portions 47a and 47b are shaped at the end of the subsequent remolding process, that is, at the bottom dead center of the remolding dies 801B and 801C, they are necessary for one remolding process. It is possible to smoothly perform the shaping of the preceding remolding portions 47a and 47b and the molding of the succeeding remolding portions 47b and 47c under a moderate molding load.

Further, since the guide surfaces 841a to 841c are provided for each of the remolding dies 801A to 801C, the guide surfaces 841a to 841c are aligned with the lower 43 side of the body portion 10 which is not subjected to the remolding process. It can be performed, and high-precision processing can be performed in a plurality of remolding processes that are repeatedly performed. Further, during each remolding process, the outer surface of the cylindrical portion 11 (body portion 10) is maintained in a state of being restrained by the guide surfaces 841a to 841c, so that the cylindrical portion is formed when a molding load is applied in the can axis C direction. It is possible to suppress the deformation of 11 in the radial direction. It is most desirable to constrain the entire circumference of the cylindrical portion 11, but even if it is partially constrained, deformation can be sufficiently suppressed.

The present invention is not limited to the configuration of the above embodiment, and various changes can be made to the detailed configuration without departing from the spirit of the present invention.
For example, in the present embodiment, a bottomed cylindrical cylinder 41 is formed in advance as a bottle can and an open end thereof is formed, but the cylinder includes a cylinder having no bottom and has a reduced diameter portion. After molding, the bottom portion separately formed may be wound around the body portion of the tubular body (intermediate molded body).

10 Body 10a, 42a Open end 11 Cylindrical part 12 Shoulder part 13 Reduced diameter part 14 Curved part 15 Mouth part 16 Preliminary reduced diameter part 17 Cylindrical upper part 20 Bottom part 21 Dome part 22 Heel part 23 Grounding part 31 Large diameter part 32 Small diameter part 33 Curl part 34 Small diameter cylinder part 40 Cup 41 Cylinder body 42 Intermediate molded body 43 Lower part 44 Scheduled diameter reduction part 45 Upper part 46a, 46b, 46c, 46d, 46e, 46f, 46g, 46h, 46i Local diameter reduction part 47a, 47b, 47c Remolding part 71A 1st inner die (inner die)
71B 2nd inner die (inner die)
71C 3rd inner die (inner die)
72A 1st outer die (outer die)
72B 2nd outer die (outer die)
72C 3rd outer die (outer die)
73a, 73b, 73c Gap 81A 1st inner die (inner die)
81B 2nd inner die (inner die)
81C 3rd inner die (inner die)
82A 1st outer die (outer die)
82B 2nd outer die (outer die)
82C 3rd outer die (outer die)
83a, 83b, 83c Gap 101 Bottle can 201 Cap 301 Bottle container 501 Bottle can manufacturing equipment 511 Work holding part (holding part)
512 Molding tool 513 Tool holding part (holding part)
514 Drive unit 515,612 Support shaft 516,613 Disk 517 Retaining device 518 Supply unit 519 Supply side star wheel 601 Discharge side star wheel 611 Discharge part 701A, 701B, 701C Diameter reduction mold 720a, 720b, 720c Molding surface 721a, 721b, 721c Convex curved surface 722a, 722b, 722c Straight forming surface 723a, 723b, 723c Tip flank surface 724a, 724b, 724c Base end flank surface 740a, 740b, 740c Tip portion 741a, 741b, 741c Guide surface 801A, 801C Molds for remolding 820a, 820b, 820c Molding surface 821a, 821b, 821c Tapered surface 822a, 822b, 822c Lower convex curved surface 823a, 823b, 823c Upper convex curved surface 824a, 824b, 824c Tip flank surface 825a, 825b, 825c Surfaces 840a, 840b, 840c Tip 841a, 841b, 841c Guide surface

Claims (3)

The diameter of the cylinder having a cylindrical body is gradually reduced from the lower side of the body toward the upper side arranged on the opening end side along the can axis direction. It is equipped with a reduced diameter part forming process to form a reduced diameter part.
The reduced diameter portion molding step is
By relatively moving the cylinder and the diameter reduction mold in the can axis direction, the molding surface of the diameter reduction mold is pressed against the outer surface of the planned diameter reduction portion from the open end portion of the body portion. The diameter reduction processing for reducing the entire region up to the planned diameter reduction portion is performed in a plurality of times while gradually reducing the processing diameter of the molding surface of the diameter reduction mold, and the diameter reduction processing is performed. Each time, the locally reduced diameter portion formed by each diameter reduction mold is formed while shifting the position from the lower side to the upper side, and each local diameter reduced portion forms a preliminary reduced diameter portion formed at intervals. Pre-formation process and
After the preforming step, the cylinder for forming the pre-reduced portion and the remolding die are relatively moved in the can axis direction, so that the remolding die is placed on the outer surface of the pre-reduced portion. The remolding process of pressing the molding surface of the above to remold is performed in a plurality of times while gradually reducing the processing diameter of the molding surface of the remolding die or gradually increasing the processing diameter. Each time processing is performed, each remolding die sequentially crushes a region wider than the space between the locally reduced diameter portions in the downward direction in the can axis direction, and the remolding is performed in sequence to have a smoothly continuous outer surface. With a remolding process to form a reduced diameter portion ,
Of the remolding processes performed a plurality of times in the remolding step, at least one subsequent remolding process performed after the preceding remolding process newly remolds a part of the pre-reduced diameter portion. At the same time, the preceding remolding portion remolded in the preceding remolding process is pressed by the molding surface of the remolding die along the reduced diameter portion, and the following from the preceding remolding portion. A method for manufacturing a can body, which comprises continuously processing up to a subsequent remolding portion to be remolded in the remolding process. Each remolding process in the remolding step is performed while gradually reducing the processing diameter of the molding surface of each remolding die, and each time the remolding process is performed, the pre-reduced diameter portion is moved from the lower side. The method for manufacturing a can body according to claim 1, wherein the can body is sequentially remolded toward the upper side. A guide surface that engages with the cylindrical outer surface of the body portion is provided at the tip end portion of the remolding die.
The method for manufacturing a can body according to claim 1 or 2, wherein the outer surface of the body is restrained by the guide surface during the remolding process performed a plurality of times in the remolding step.

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