JP7120809B2 - Can body and its manufacturing method - Google Patents

Description

The present invention relates to a metal can body filled with a content such as a beverage, which is a bottle-shaped can body having a shoulder portion on the opening side of the body portion, the diameter of which is smaller than that of the straight body portion on the bottom side. It relates to the manufacturing method thereof.

2. Description of the Related Art Bottle-shaped can bodies (bottle cans) made of steel, aluminum alloy, or the like are known as containers to be filled with contents such as beverages. The body of a bottle-shaped can generally has a large-diameter cylindrical straight body, a shoulder portion whose diameter gradually decreases from the upper end of the straight body portion upward in the can axial direction, and a shoulder portion. a small-diameter opening formed continuously from the upper end of the and opening to the outside. Moreover, in such a can body, the shoulder portion is designed to have an uneven shape.

For example, Patent Literature 1 discloses a bottle can in which a plurality of grooves extending along the inclined direction are provided on the circumferential surface of the shoulder portion at intervals in the circumferential direction (Fig. 1 of Patent Literature 1); A bottle can (Fig. 9 of Patent Document 1) in which a plurality of grooves formed continuously along the circumferential direction are provided at intervals in the can axial direction (axial direction), and a plurality of grooves are formed at predetermined intervals in the circumferential direction. 12 of Patent Document 1) is disclosed. Patent Document 1 also describes that these grooves are formed by pressing the shoulder portion radially inward and downward in the axial direction of the can with a mold.

JP-A-2004-123231

However, the switching portion (lower bent portion) between the straight body portion and the shoulder portion located below the shoulder portion in the can axis direction is formed in a bent (curved) shape, and is formed into a flat conical shape. The rigidity is higher than that of the portion (tapered portion) formed in the vertical direction. For this reason, it is difficult to process the lower bent portion with a mold, and the mold hits the lower bent portion more strongly than the tapered portion. It is difficult to form a uniform concavo-convex shape with the lower bent portion. In particular, since the rigidity of the lower bent portion is high, if the pressing force of the mold is small, springback or the like will occur, making it difficult to form the concave-convex shape. On the other hand, if the pressing force of the mold is too large, the lower curved portion will be processed too deeply, and the concave and convex shape of the lower curved portion will be too conspicuous compared to the tapered portion, and the shape of the shoulder will be distorted and lowered. There is a possibility that the side bending portion may protrude in the radial direction more than the straight body portion. In addition, the can body having such a distorted shape is likely to be caught in the conveying path during conveying, resulting in a decrease in conveyability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly transportable can body in which the distortion of the can body is suppressed and the shoulder portion is designed with uneven shapes.

The can body of the present invention comprises a cylindrical straight body portion, a shoulder portion whose diameter gradually decreases as it goes upward in the can axial direction from the upper end of the straight body portion, and an opening formed above the shoulder portion to the outside. The shoulder portion has a lower bent portion that bends radially inward from the upper end of the straight body portion, and gradually upward from the upper end of the lower bent portion. a conical tapered portion with a reduced diameter, wherein the lower bent portion includes an odd number of first concave portions formed at equal intervals in the circumferential direction and concave inward in the radial direction; a plurality of first boundary apexes formed between the first recesses and projecting radially outward relative to the first recesses ; A plurality of second recesses formed at equal intervals in the circumferential direction above the top of the first boundary in the can axial direction and recessed radially inward, and a plurality of second recesses formed between the second recesses. , and a plurality of second boundary apexes that protrude radially outward relative to the second recesses, and a surface circumscribing the first boundary apex and the second boundary apex With respect to a reference plane, the first recess is folded up and down in the can axial direction at the deepest portion of the first recess, which is the deepest position where the vertical distance from the reference plane is the largest, and extends along the circumferential direction. and the deepest part of the first recess is located above both ends contacting the first boundary tops formed on both sides of the curved part in the circumferential direction in the can axial direction. each of the second recesses is folded up and down in the can axial direction at the deepest portion of the second recesses, which is the deepest position where the vertical distance from the reference surface is the largest, and extends along the circumferential direction. A curved portion is provided, and the deepest portion of the second recess and both end portions of the second recess contacting second boundary top portions formed on both sides in the circumferential direction of the curved portion of the second recess are formed at the same position in the can axial direction. Each first recess has two first boundary tops formed on both sides in the circumferential direction of the first recess, and one second boundary formed between these first boundary tops. and each second recess is formed between at least two second boundary tops formed on both sides in the circumferential direction of the second recess and these second boundary tops. The shortest distance L1 from the deepest part of the first recess to the second boundary top surrounding the first recess is from the deepest part of the second recess It is provided to be shorter than the shortest distance L2 to the first boundary top surrounding the second recess .

By forming an odd number of first recesses arranged at equal intervals in the circumferential direction in the lower bent portion of the shoulder portion, a first recess is always provided at a radially opposite position (180° opposite side) of one first recess. One boundary top portion is formed, and the first concave portion and the other first concave portion do not face each other at the opposite positions in the radial direction. On the other hand, when an even number of first recesses are formed at equal intervals in the circumferential direction, another first recess is formed at a radially opposite position (180° opposite side) to one first recess. In this case, when machining these opposed first recesses, the lower bent portions (shoulders) are strongly pressed radially inward at positions opposed by 180°. As a result, the shoulder portion is likely to be crushed radially inward, which may cause other portions to protrude radially outward, distorting the shape of the can and reducing the transportability of the can. In this respect, by forming an odd number of first recesses, a uniform pressing force can be applied in the circumferential direction during processing of the first recesses, compared to the case where an even number of first recesses are formed. Therefore, it is possible to uniformly form the plurality of first recesses even in the lower bent portion having high rigidity. Therefore, it is possible to prevent the can body from being distorted, and it is possible to satisfactorily form the design of the uneven shape on the shoulder portion, and to ensure good transportability of the designed can body.

The entire shoulder portion has a shape that gradually decreases in diameter as it goes upward in the can axial direction. be done. The first concave portion is formed in contact with the first boundary apex formed in the greatly bent lower bent portion at both ends of the bent portion, but is formed below the lower bent portion at the deepest portion of the bent portion. It is formed on the upper side closer to the straight tapered portion than on the side. In this way, by forming the deepest part of the curved part above both ends, the shape of the first boundary apex that is close to both ends in the circumferential direction while reducing the amount of processing of the entire first concave part can be formed with certainty. In addition, by reducing the amount of processing of the first recess, the pressing force required for processing can be reduced, so that it is possible to further suppress the distortion of the shape of the can body. The shape of the boundary apex can be accentuated.

When forming not only the first recess but also the second recess in the shoulder portion to form a plurality of recesses, the shortest distance L1 from the deepest portion of the first recess to the second boundary top is defined as the maximum depth of the second recess. The first boundary top and the second boundary top can be uniformly formed by making the distance L2>L1 from the first boundary top to the first boundary top. Therefore, the first boundary apex and the second boundary apex formed on the reference plane can be emphasized in the lower bent portion with high rigidity and the tapered portion with lower rigidity than the lower bent portion. In addition, since the distortion of the can body can be suppressed, it is possible to satisfactorily form the design of the concave-convex shape on the shoulder portion, and to ensure good transportability of the designed can body.

As a preferred embodiment of the can body of the present invention, the deepest part of the first recess is formed with a smaller vertical distance from the reference plane than the deepest part of the second recess.

The deepest part of the first recess formed near the upper end of the straight body part and the deepest part of the second recess formed at a position farther from the straight body part than the deepest part of the first recess from the reference plane By reducing the vertical distance and forming a shallow portion, the processing amount of the first recess formed in the lower bent portion with high rigidity is reduced to the amount of machining of the second recess formed in the tapered portion with lower rigidity than the lower bent portion. It can be smaller than the processing amount. Therefore, the pressing force necessary for processing the first concave portion and the second concave portion can be made uniform, the first boundary top portion and the second boundary top portion can be formed more uniformly, and distortion of the can body can be further suppressed. .

As a preferred embodiment of the can body of the present invention, the shoulder further has an upper bent portion that bends radially inward from the upper end of the tapered portion, and the upper bent portion extends in the circumferential direction. an odd number of upper recesses formed at equal intervals and concave radially inward from the reference surface; and a plurality of upper boundary apexes that are outwardly convex and form part of the reference plane.

The upper bent portion also has a shape bent radially inward, and is a portion having higher rigidity than the tapered portion, similar to the lower bent portion. Even when the upper bent portion is designed with an uneven shape, by forming an odd number of upper concave portions in the same manner as in the lower bent portion, each upper concave portion is formed more uniformly than forming an even number of upper concave portions. It is possible to suppress the distortion of the can body. Therefore, it is possible to ensure good transportability of the can body.

In the can body manufacturing method of the present invention, a cylindrical body having a conical shoulder is formed continuously from the upper end of the straight body, and an annular shoulder forming mold is formed from the open end of the cylindrical body. By moving axially of the can and pressing against the conical shoulder, the conical shoulder is partially plastically deformed to form the first recess and the first boundary apex. With this manufacturing method, the unevenness of the shoulder can be formed by the same processing method as the necking process for forming the conical shoulder, which is efficient.

According to the present invention, it is also possible to form a design with an uneven shape on the lower bent portion arranged on the lower side of the shoulder portion in the can axial direction, and the shape of the can body is distorted when the uneven shape is processed on the shoulder portion. Since it is possible to suppress the occurrence of this, it is possible to ensure good transportability of the can body.

It is a front view of the can of embodiment of this invention. 2 is a cut end view through the can shaft of the can body shown in FIG. 1; FIG. It is a front view of the principal part which expanded near the upper part of the can body shown in FIG. FIG. 4 is a top view of the shoulder viewed from the direction of arrow A in FIG. 3; FIG. 5 is a top view of a main portion of the shoulder portion shown in FIG. 4; 4 is a cut end view of the can body taken along line BB shown in FIG. 3; FIG. 4 is a cut end view of the can body taken along line CC shown in FIG. 3; FIG. Figure 4 is a cut end view of the can body taken along line DD shown in Figure 3; Figure 4 is a cut end view of the can body taken along line EE shown in Figure 3; Fig. 2 is a front view showing a can body and a cap, with the right half section taken from the center passing through the can axis. FIG. 4 is a cut end view through the can axis showing the vicinity of the upper portion of the cylindrical body before the can body is unevenly shaped and a shoulder forming die used for processing the cylindrical body.

An embodiment of a can body according to the present invention will be described below with reference to the drawings.
As shown in FIGS. 1 and 2, a can body (bottle can) 101 according to an embodiment of the present invention has an opening 115 that opens to the outside and is formed in a bottle shape as a whole. After the can body 101 is filled with a content such as a beverage through the opening 115, the opening 115 is sealed by attaching (sealing) the cap 102 to the opening 114 to form a bottle container ( See Figure 10).

FIG. 1 is a front view showing the entire can body 101. FIG. FIG. 2 is a cut end view through the can axis O of the can body 101 . FIG. 3 is a front view of a main portion in which the vicinity of the upper portion of the can body 101 is enlarged. 4 is a top view of the shoulder portion 112 of the can body 101 viewed from the direction of arrow A in FIG. 3. FIG. FIG. 5 is a top view showing essential parts of the shoulder portion 112 shown in FIG. 6 to 9 show the can body 101 obtained by radially (horizontally) cutting the recesses 211, 221, 231, 241 formed in the shoulder portion 112 of the can body 101 at the deepest portions P1 to P4. FIG. 4 is a cut end view; Among them, FIG. 6 is a cut end view of the deepest part P1 of the first recess 211 obtained by cutting the can body 101 along the line BB in FIG. FIG. 7 is a cut end view of the deepest part P2 of the second recess 221 obtained by cutting the can body 101 along line CC in FIG. FIG. 8 is a cut end view of the deepest part P3 of the third recess 231 obtained by cutting the can body 101 along line DD of FIG. 9 is a cut end view of the deepest part P4 of the fourth concave portion 241 obtained by cutting the can body 101 along the line EE in FIG. 10 shows the right half of the can body 101 and the cap 102 attached to the mouth portion 114 of the can body 101 as a cut end surface passing through the can axis O. FIG. FIG. 11 also shows the vicinity of the upper portion of the cylindrical body 100 before the shoulder portion 112 of the can body 101 is given an uneven shape, and a shoulder forming mold for giving an uneven shape to the conical shoulder portion 112a of the cylindrical body 100. 501 and .

The can body 101 is made of aluminum, aluminum alloy, or other metal, and as shown in FIG. It is formed in a cylindrical shape with a bottom.

As shown in FIG. 1, the body portion 110 and the bottom portion 120 are arranged coaxially with each other. In the direction along the can axis O (direction of the can axis O), the direction from the opening 115 to the bottom 120 is defined as downward, and the direction from the bottom 120 to the opening 115 is defined as upward. The vertical direction is defined in the same manner as the direction shown in FIG. A direction orthogonal to the can axis O is called a radial direction. Of the radial directions, the direction approaching the can axis O is radially inward (inward), and the direction away from the can axis O is radially outward (inward). outside). The direction of rotation around the can axis O is defined as the circumferential direction. Further, in the present embodiment, the uneven shape of the can body 101 represents the uneven shape of the outer surface (appearance surface) of the can body 101 unless otherwise specified.

As shown in FIG. 1, the barrel portion 110 includes a straight barrel portion 111 formed in a large-diameter cylindrical shape on the bottom portion 120 side, and a portion extending upward in the can axis O direction from the upper end of the straight barrel portion 111 (on the opening 115 side). ), a neck portion 113 connected to the upper end of the shoulder portion 112 and extending upward in the direction of the can axis O, and a small diameter opening to the outside connected to the upper end of the neck portion 113. and a mouth 114 . The straight body portion 111 , the shoulder portion 112 , the neck portion 113 and the mouth portion 114 each form an annular shape extending over the entire circumferential direction of the body portion 110 .

1 and 3, the shoulder portion 112 includes a lower bent portion 21 that bends radially inward from the upper end of the straight body portion 111, and an upper end of the lower bent portion 21. and an upper bent portion 23 bent radially inward from the upper end of the tapered portion 22, and the lower end of the shoulder portion 112. is formed to have the largest diameter, and the upper end of the shoulder portion 112 is formed to have the smallest diameter. The upper end of the upper bent portion 23 is connected to the lower end of the neck portion 113 .

In addition, in the entire region from the lower bent portion 21 to the upper bent portion 23 of the shoulder portion 112, a conical reference plane S (indicated by a two-dot chain line in FIGS. 2 and 3) is provided radially inwardly. A plurality of recessed portions 211, 221, 231, 241 which are concave toward each other are regularly formed at intervals. The reference plane S, as shown in FIG. 11, represents the same plane as the outer surface of the conical shoulder 112a of the cylindrical body 100 before the recesses 211, 221, 231, 241 are formed in the can body 101. As shown in FIG. This reference plane S is a plane that circumscribes boundary apexes 212, 222, 232, and 242, which will be described later. As shown in FIG. 2, if the angle (tilt angle) formed by the reference plane S and the can axis O is α, the tilt angle α of the reference plane S is set at, for example, 10° or more and 60° or less.

Of the recesses 211, 221, 231, 241 formed in the shoulder portion 112, the plurality of first recesses 211 formed on the lowermost side of the shoulder portion 112 are as shown in FIGS. , an odd number (nine in this example) are formed at regular intervals in the circumferential direction of the lower bent portion 21 . Between the first recesses 211 of the lower bent portion 21, as shown in FIGS. One boundary top 212 is formed. Each first boundary apex 212 is formed on the reference plane S and forms part of the reference plane S as described above.

In addition, as shown in FIGS. 3 to 5, in the circumferential direction, the first recess 211 is in contact with two first boundary apexes 212, 212 formed on both sides of the first recess 211 in the circumferential direction. , in the can axis O direction, it is in contact with one second boundary top 222 formed between these first boundary tops 212, 212, and two first boundary tops 212, 212 and one second boundary Surrounded by top 222 . The ridgeline between each first recess 211 and the reference surface S (the outer peripheral edge of the first recess 211) is substantially triangular with the three points of the first boundary apexes 212, 212 and the second boundary apex 222 as vertices. formed.

In addition, the first recess 211 is folded up and down in the can axis O direction at the deepest portion P1, which is the deepest position where the vertical distance from the reference plane S in the first recess 211 is the largest, and extends along the circumferential direction. An extending curved portion 213 is formed. As shown in FIGS. 3 to 5, the curved portion 213 is provided at both ends in the circumferential direction in contact with two first boundary top portions 212, 212 formed on both sides. A deepest portion P<b>1 of the first concave portion 211 is formed between both ends of the curved portion 213 . As shown in FIG. 3, the deepest part P1 of the first recess 211 is formed above both ends of the curved part 213. It is formed in the shape of an arch arranged at the uppermost position in the O direction.

The deepest portion P1 of the first concave portion 211 (curved portion 213) is preferably formed at a position exceeding 4 mm upward in the can axis O direction from the upper end of the straight body portion 111 so as not to be too deeply processed. . In other words, as shown in FIG. 3, it is preferable that the vertical distance H1 parallel to the can axis O from the upper end of the straight body portion 111 to the deepest portion P1 of the curved portion 213 exceeds 4 mm. On the other hand, both ends of the curved portion 213 are preferably formed within a range of 4 mm or less upward in the can axis O direction from the upper end of the straight body portion 111 , and are close to the first boundary top portion 212 . In other words, it is preferable to set the vertical distance H2 parallel to the can axis O from the upper end of the straight body portion 111 to both ends of the curved portion 213 to 4 mm or less. When the vertical distance H1 exceeds 4 mm, if the vertical distance H2 exceeds 4 mm as well as the vertical distance H1, it is difficult to process the vicinity of the lower portion of the lower curved portion 21 and the tapered portion 22. As a result, it becomes difficult to uniformly form the uneven design on the shoulder portion 112 .

In this way, since the deepest part P1 of the first recessed part 211 is formed above both ends of the curved part 213, as shown in FIG. On the cut end surface, the first recess 211 and the second recess 221 are formed adjacent to each other in the circumferential direction, and the cross section of the can body 101 is the outer peripheral edge of the first recess 211 and the outer peripheral edge of the second recess 221. It is formed in a substantially octagonal shape with a common edge line as the vertex. In addition, the reference surface S circumscribes the ridgeline between the first concave portion 211 and the second concave portion 221 , and the ridgeline constitutes a part of the reference surface S.

The second recesses 221 are formed above the first boundary tops 212 formed between the first recesses 211 . Further, the second recesses 221 are formed so as to extend from the lower bent portion 21 to the tapered portion 22, and as shown in FIG. (nine) are formed. Between each of the second recesses 221 , a second boundary top portion 222 is formed that protrudes radially outward relative to the second recesses 221 . The second boundary top portion 222 is also formed on the reference plane S and constitutes a part of the reference plane S, like the first boundary top portion 212 .

In addition, as shown in FIGS. 3 to 5, in the circumferential direction, the second recess 221 is in contact with two second boundary apexes 222, 222 formed on both sides of the second recess 221 in the circumferential direction. , in the can axis O direction, it is in contact with one first boundary top 212 and one third boundary top 232 formed between these second boundary tops 222, 222, and two second boundary tops 222 , 222 , one first bounding apex 212 and one third bounding apex 232 . The ridgeline between each of the second recesses 221 and the reference surface S (the outer peripheral edge of the second recesses 221) is defined by the four points of the second boundary tops 222, 222, the first boundary top 212, and the third boundary top 232. It is formed in a substantially rhombic shape with an apex.

In addition, the second recess 221 is folded up and down in the direction of the can axis O at the deepest portion P2, which is the deepest position of the second recess 221 where the vertical distance from the reference plane S is the largest, and extends along the circumferential direction. An extending curved portion 223 is formed. As shown in FIGS. 3 to 5, the curved portions 223 are provided at both ends in the circumferential direction in contact with the second boundary top portions 222 formed on both sides. A deepest portion P<b>2 of the second recess 221 is formed between both ends of the curved portion 223 . As shown in FIG. 3, the deepest part P2 of the second recess 221 is formed at the same position (at the same height) as both ends of the curved part 223 in the can axis O direction.

In this way, the deepest part P2 of the second recessed part 221 is formed at the same position as both ends of the curved part 223. Therefore, as shown in FIG. The cut end face becomes an end face along the curved portion 223 . 7, a second concave portion 221 and a second boundary top portion 222 are formed adjacent to each other in the circumferential direction on the cut end face of the can body 101 shown in FIG. , and each second concave portion 221 (curved portion 223) as one side. In addition, as shown in FIG. 7, the reference surface S circumscribes each of the second boundary top portions 222, and each of the second boundary top portions 222 constitutes a part of the reference surface S as described above.

Also, in the can body 101, as shown in FIG. to the first boundary top portion 212 surrounding the second concave portion 221 is provided to be shorter than the shortest distance L2. Also, the vertical distance W1 from the reference surface S of the first recess 211 to the deepest portion P1 is set smaller than the vertical distance W2 from the reference surface S of the second recess 221 to the deepest portion P2 (W1<W2). , the deepest part P1 of the first recess 211 is formed with a smaller vertical distance from the reference plane S than the deepest part P2 of the second recess 221 .

The third recess 231 is formed above the second boundary top 222 formed between the second recesses 221 . Further, the third recesses 231 are formed in the tapered portion 22, and as shown in FIG. , is formed. A third boundary top portion 232 is formed between each of the third recesses 231 so as to protrude radially outward relative to the third recesses 231 . The third boundary top portion 232 is also formed on the reference plane S, and constitutes a part of the reference plane S, like the first boundary top portion 212 and the second boundary top portion 222 .

Further, as shown in FIGS. 3 to 5, in the circumferential direction, the third recess 231 is in contact with two third boundary top portions 232, 232 formed on both sides of the respective third recess 231 in the circumferential direction. , in the direction of the can axis O, it is in contact with one second boundary top 222 and one fourth boundary top 242 formed between these third boundary tops 232, 232, and two third boundary tops 232 , 232 , one second bounding apex 222 and one fourth bounding apex 242 . The ridgeline between each third concave portion 231 and the reference surface S (the outer peripheral edge of the third concave portion 231) is defined by these four points of the third boundary top portions 232, 232, the second boundary top portion 222, and the fourth boundary top portion 242. It is formed in a substantially rhombic shape with an apex.

Further, the third recess 231 is folded up and down in the can axis O direction at the deepest portion P3, which is the deepest position of the third recess 231 where the vertical distance from the reference surface S is the largest, and extends along the circumferential direction. An extending curved portion 233 is formed. As shown in FIGS. 3 to 5, the curved portions 233 are provided at both ends in the circumferential direction in contact with third boundary top portions 232 formed on both sides. A deepest portion P3 of the third recess 231 is formed between both ends of the curved portion 233 . The deepest portion P3 of the third concave portion 231 is formed at the same position in the can axis O direction as both end portions of the curved portion 233, as shown in FIG.

In this way, the deepest part P3 of the third recess 231 is formed at the same position as both ends of the curved part 233. Therefore, as shown in FIG. The cut end face becomes an end face along the curved portion 233 . 8, a third concave portion 231 and a third boundary top portion 232 are formed adjacent to each other in the circumferential direction on the cut end face of the can body 101 shown in FIG. , and each third concave portion 231 (curved portion 233) as one side. In addition, as shown in FIG. 8, the reference surface S circumscribes each third boundary top portion 232, and each third boundary top portion 232 constitutes a part of the reference surface S as described above.

The fourth recess 241 is formed above the third boundary top 232 formed between the third recesses 231 . The fourth recess 241 is formed across the tapered portion 22 and the upper curved portion 23, and as shown in FIG. , are formed at equal intervals in the circumferential direction with an odd number (9). A fourth boundary top portion 242 is formed between each of the fourth recesses 241 so as to protrude radially outward relative to the fourth recesses 241 . The fourth boundary top portion 242 is also formed on the reference plane S and constitutes a part of the reference plane S, like the first boundary top portion 212 , the second boundary top portion 222 and the third boundary top portion 232 . In addition, in the can body 101 of the present embodiment, the fourth concave portion 241 is the upper concave portion in the present invention, and the fourth boundary top portion is the upper boundary top portion in the present invention.

In addition, as shown in FIGS. 3 to 5, in the circumferential direction, the fourth recessed portion 241 is in contact with two fourth boundary top portions 242, 242 formed on both sides of the respective fourth recessed portion 241 in the circumferential direction. , in the direction of the can axis O, is in contact with one third boundary top 232 formed between these fourth boundary tops 242, 242, and two fourth boundary tops 242, 242 and one third boundary Surrounded by top 232 . The ridgeline between each fourth recess 241 and the reference surface S (the ridgeline of the fourth recess 241) is a substantially triangular shape (fan-shaped ).

In addition, the fourth recess 241 is folded up and down in the can axis O direction at the deepest portion P4, which is the deepest position where the vertical distance from the reference surface S in the fourth recess 241 is the largest, and extends along the circumferential direction. An extending curved portion 243 is formed. As shown in FIGS. 3 to 5, the curved portion 243 is provided in contact with the fourth boundary top portion 242 at both ends formed on both sides in the circumferential direction. A deepest portion P<b>4 of the fourth recess 241 is formed between both ends of the curved portion 243 . The deepest portion P4 of the fourth concave portion 241 is formed at the same position in the can axis O direction as both end portions of the curved portion 243, as shown in FIG.

In this way, the deepest part P4 of the fourth recess 241 is formed at the same position as both ends of the curved part 243. Therefore, as shown in FIG. The cut end face becomes an end face along the curved portion 243 . Further, in the cut end face of the can body 101 shown in FIG. 9, a fourth concave portion 241 and a fourth boundary top portion 242 are formed adjacent to each other in the circumferential direction. , and each fourth concave portion 241 as one side. In addition, as shown in FIG. 9, the reference surface S circumscribes each of the fourth boundary top portions 242, and each fourth boundary top portion 242 constitutes a part of the reference surface S as described above.

As described above, the shoulder portion 112 of the can body 101 has recessed portions 211, 221, 231, and 241 in the circumferential direction and the direction of the can axis O, and these recessed portions 211, 221, 231, and 241 are provided with By alternately forming convex boundary apexes 212, 222, 232, and 242 that are relatively convex, a pattern of uneven shapes is given. Further, in the can body 101 of the present embodiment, as shown in FIGS. By forming 243, the shoulder portion 112 is given a diamond-cut pattern.

The mouth portion 114 formed in the upper portion of the trunk portion 110 includes a large diameter portion 41 that is once enlarged in diameter at the upper end of the neck portion 113, a small diameter portion 42 that is again reduced in diameter at the upper end of the large diameter portion 41, and a small diameter portion. and a curled portion 43 formed in an opening 115 at the upper end of the portion 42 . A threaded portion 44 is formed in the small diameter portion 42 .

Further, the bottom portion 120 of the can body 101 is positioned on the can axis O and is formed to bulge upward (inside the body portion 110). and a heel portion 122 that connects the lower end of the trunk portion 110 . The connecting portion between the dome portion 121 and the heel portion 122 is placed on the ground surface (mounting surface) so that the can body 101 is in an upright posture (a posture in which the opening 115 shown in FIG. 1 faces upward). A ground part 123 is in contact with the ground surface when placed. The ground contact portion 123 protrudes downward most from the bottom portion 120 and has an annular shape extending in the circumferential direction.

To give an example of various dimensions of the can body 101 configured in this way, the plate thickness of the can body 101 is 0.250 mm to 0.500 mm in the original plate thickness before molding. Further, in a longitudinal cross-sectional view passing through the can axis O of the can body 101 shown in FIG. The radius of curvature of the outer surface of the portion 21) is 6 mm to 25 mm, and the radius of curvature R12 of the upper curved portion 23 (the radius of curvature of the outer surface of the upper curved portion 23) is 1 mm to 12 mm. However, the above dimensions are not limited to the above numerical ranges.

In the case of the can body 101 shown in FIG. 1, the outer diameter Db of the straight body portion 111 is 66 mm, the curvature radius R11 of the lower bent portion 21 is 10 mm, the curvature radius R12 of the upper bent portion 23 is 6 mm, and the taper portion 22 is inclined. The angle α is assumed to be 28°.

An example of a method for manufacturing the can body 101 configured as described above will be described. The can body 101 is formed by forming a plate material such as an aluminum alloy. Although illustration is omitted, a relatively large-diameter shallow cup is formed by punching and drawing a plate material, and then drawing and ironing (DI processing) are applied again to this cup to obtain a predetermined height. A cylindrical body with a bottom is molded. By DI processing, the bottom portion of the cylindrical body is formed into the shape of the bottom portion 120 of the final can body 101 . Also, the upper end of the cylindrical body is trimmed and cut. Next, by gradually reducing the diameter of the upper portion of the cylinder by neck-in processing, as shown in FIG. 11, a cylinder 100 having a conical shoulder portion 112a is formed. Concave portions 211, 221, 231 and 241 are formed in the conical shoulder portion 112a of the cylindrical body 100 to form the can body 101 having an uneven shape.

For example, a shoulder forming mold 501 as shown in FIG. 11 is used to form the uneven shape on the conical shoulder 112a of the cylindrical body 100. As shown in FIG. As shown in FIG. 11 , a shoulder forming mold 501 is formed in a cylindrical shape, and its inner peripheral surface serves as a molding surface (pressing surface) 510 . The molding surface 510 has a conical bottom portion 511 whose diameter gradually decreases from the bottom to the top. The bottom portion 511 has a shape slightly enlarged in diameter from the reference surface S of the shoulder portion 112 of the can body 101 (the outer surface of the conical shoulder portion 112a of the cylindrical body 100) at the cut end surface passing through the can axis O shown in FIG. , and is formed at the same inclination angle α as the reference plane S. In addition, the opening diameter Di of the lower side of the shoulder forming mold 501 is also formed to be slightly larger than the outer diameter Db of the straight body portion 111 of the cylindrical body 100 (can body 101). The difference (Di-Db) is, for example, 0.05 mm to 1.0 mm.

The molding surface 510 is also provided with a plurality of molding protrusions 512a, 512b, 512c, and 512d protruding from the bottom surface 511 at intervals. Concave portions 211, 221, 231 and 241 are formed by these forming convex portions 512a to 512d. In this way, the bottom portion 511 is formed in a groove shape at positions corresponding to the ridgelines of the boundary tops 212, 222, 232, 242 and the recesses 211, 221, 231, 241 between the molding projections 512a to 512d. ing.

The uneven shape is formed on the conical shoulder portion 112a by inserting the cylindrical body 100 inside the shoulder forming mold 501 and transferring the shape of the molding surface 510 to the conical shoulder portion 112a. Specifically, the shoulder forming mold 501 is moved in the can axial direction from the open end of the cylindrical body 100, and the molding surface 510 thereof is pressed against the outer peripheral surface of the shoulder 112a, and the outer periphery of the conical shoulder 112a is pressed. Pressing the face radially inwardly and downwardly in the direction of the can axis O by the forming surface 510 partially plastically deforms the conical shoulder 112a to form each of the recesses 211,221,231,241. At this time, since the bottom portion 511 of the forming surface 510 is formed in a shape having a slightly larger diameter than the reference surface S, it is possible to allow the cylindrical body 100 to bulge slightly when forming the conical shoulder portion 112a. Therefore, at the time when the molding surface 510 of the shoulder forming die 501 and the conical shoulder 112a of the cylindrical body 100 start contacting each other (when molding starts), the molding surface 510 is easily pressed against the conical shoulder 112a. While deforming the conical shoulder 112a, the shoulder forming mold 501 and the cylindrical body 100 can be reliably moved to a desired position. Therefore, the shapes of the molding projections 512a to 512d of the molding surface 510 can be reliably transferred to the conical shoulder portion 112a.

The outer surface portion of the conical shoulder portion 112a facing the bottom surface portion 511 is basically not machined by the forming surface 510, and the formed conical shoulder portion 112 has a reference surface S left. Thereby, the ridgelines of the recesses 211, 221, 231, 241 and the boundary tops 212, 222, 232, 242 are formed.

In addition, after forming an uneven shape consisting of concave portions 211, 221, 231, 241, etc. in the cylindrical body 100, a threaded portion is further formed in the mouth portion 114a, and the open end portion 45 thereof is curled by curling. form a part. As a result, as shown in FIGS. 1 and 3, the can body 101 having the threaded portion 44 and the curled portion 43 is manufactured.

As described above, the can body 101 is formed with an odd number of first recesses 211, second recesses 221, third recesses 231, and fourth recesses 241 at regular intervals in the circumferential direction. For this reason, in the lower bent portion 21 of the shoulder portion 112, the first boundary top portion 212 is always formed at a radially facing position (opposite side of 180°) to one first concave portion 211. , the first concave portion 211 and the other first concave portion 211 do not face each other. On the other hand, when an even number of first recesses 211 are formed at equal intervals in the circumferential direction, another first recess 211 is formed at a radially opposing position (180° opposite side) of one first recess 211. be done. In this case, when the first concave portions 211, 211 facing each other are machined, the lower bent portion 21 of the conical shoulder portion 112a is strongly pressed radially inward at positions facing each other by 180°. Therefore, the shoulder portion 112 is likely to be crushed radially inward, which may cause other portions to protrude radially outward, distorting the shape of the can body 101 and reducing the transportability of the can body 101. There is

In this respect, by forming an odd number of the first recesses 211, it is possible to apply a uniform pressing force in the circumferential direction during machining of the first recesses 211, compared to the case of forming an even number of the first recesses 211. can. Therefore, the plurality of first concave portions 211 can be uniformly formed even in the lower bent portion 21 having high rigidity.

Both ends of the curved portion 213 of the first concave portion 211 are formed in contact with the first boundary top portion 212 formed in the lower curved portion 21. It is formed on the upper side closer to the straight tapered portion 22 than on the lower side of the portion 21 . In this way, by forming the deepest part P1 of the curved part 213 above the both ends, the machining amount of the entire first concave part 211 is reduced, while the inner part of the curved part 213 is located close to the both ends of the curved part 213 in the circumferential direction. The shape of the first boundary apex 212 can be made distinct. In addition, by reducing the amount of machining of the first recess 211, the pressing force required for machining can be reduced, so that the shoulder 112 is less likely to be crushed inward in the radial direction, and distortion of the shape of the can body 101 is further suppressed. can.

Further, when both ends of the curved portion 213 of the first concave portion 211 are formed within a range of 4 mm or less from the upper end of the straight body portion 111 upward in the direction of the can axis O, the deepest portion P1 of the curved portion 213 is The shape of the first boundary top portion 212 can be emphasized, and the first concave portion 211 can be formed by forming the first boundary top portion 212 at a position exceeding 4 mm upward in the direction of the can axis O from the upper end of the straight body portion 111 above the portion. The total amount of processing can be reliably reduced. Therefore, it is possible to reliably prevent the shape of the can body 101 from being distorted, and it is possible to satisfactorily form the uneven design on the shoulder portion 112 .

In addition, as in the present embodiment, when not only the first recess 211 but also the second recess 221 are formed in the shoulder portion 112 to form the recesses 211 and 221 in a plurality of stages, the deepest portion P1 of the first recess 211 to the second boundary top portion 222 is made smaller than the shortest distance L2 from the deepest portion P2 of the second recessed portion 221 to the first boundary top portion 212, and the relationship of L2>L1 is satisfied, thereby making the can body By suppressing the distortion of 101, the first boundary top portion 212 and the second boundary top portion 222 can be uniformly formed. Therefore, both the first boundary top portion 212 and the second boundary top portion 222 formed on the reference plane S are It can be made to stand out.

In addition, the deepest part P1 of the first recess 211 formed near the upper end of the straight body part 111 and the second recess 221 formed at a position farther from the straight body part 111 than the deepest part P1 of the first recess 211 By making the vertical distance from the reference plane S smaller and shallower than the deepest portion P2 (W1<W2), the processing amount of the first recess 211 formed in the lower bent portion 21 with high rigidity can be reduced. It can be made smaller than the processing amount of the second concave portion 221 formed over the tapered portion 22 having lower rigidity than the side bent portion 21 . Therefore, the pressing force necessary for processing the first concave portion 211 and the second concave portion 221 can be made uniform, the first boundary top portion 212 and the second boundary top portion 222 can be formed more uniformly, and the can body is prevented from being distorted. can be further suppressed.

As described above, according to the present embodiment, the can body 101 can be prevented from being distorted, and the shoulder portion 112 can be well designed with uneven shapes. can be secured.

In the above-described embodiment, the recesses 211, 221, 231, and 241 having triangular or rhombic outer peripheral edges are combined to form an uneven shape on the shoulder 112. However, the shape of the outer peripheral edge of the recess is triangular. or rhombic shape. For example, it may be formed in a circular shape or a polygonal shape with a quadrangle or more. Further, the recesses may be configured with 1st to 3rd stages, which is less than 4 stages, or may be configured with more than 4 stages. Also, the number of recesses formed in the circumferential direction is not limited to nine, and may be less than nine or more than nine. Furthermore, the uneven shape formed on the shoulder may be formed in the entire region of the shoulder, formed only in the lower bent portion, or formed in the lower bent portion and the upper bent portion. A combination can be employed.

Moreover, the present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made to the detailed configurations without departing from the scope of the present invention.
For example, in the above embodiment, a bottomed cylindrical can body in which the bottom portion 120 and the body portion 110 are integrally formed has been described, but the can body does not necessarily have a bottom portion, and the shoulder portion includes a bottom portion. It also includes those that wind up the bottom part separately formed on the trunk part after molding the concave-convex shape.
Moreover, the present invention is not limited to a can body having a threaded portion at the mouth portion, but can also be applied to a can body having a curled portion formed at the opening of the can body in the same manner as a bottle mouth.

21 Lower curved portion 22 Tapered portion 23 Upper curved portion 41 Large diameter portion 42 Small diameter portion 43 Curl portion 44 Threaded portion 45 Open end portion 100 Cylindrical body 101 Can body 102 Cap 110 Body portion 111 Straight body portion 112 Shoulder portion 112a Conical shape Shoulder 113 Neck 114, 114a Mouth 115 Opening 120 Bottom 121 Dome 122 Heel 123 Ground part 211 First recess (recess)
212 first boundary top (boundary top)
213 curved portion 221 second recess (recess)
222 second boundary top (boundary top)
223 curved portion 231 third recess (recess)
232 third boundary top (boundary top)
233 curved portion 241 fourth concave portion (recessed portion)
242 4th Boundary Top (Boundary Top)
243 curved portion 501 shoulder forming mold 510 molding surface 511 bottom surface portions 512a, 512b, 512c, 512d molding projections

Claims (4)

It has a cylindrical straight body portion, a shoulder portion whose diameter gradually decreases from the upper end of the straight body portion upward in the can axial direction, and a mouth portion formed above the shoulder portion and opening to the outside. death,
The shoulder portion includes a lower bent portion that bends radially inward from the upper end of the straight body portion, and a conical tapered portion that gradually decreases in diameter upward from the upper end of the lower bent portion. , has
The lower bent portion is
an odd number of first recesses formed at equal intervals in the circumferential direction and concave radially inward;
a plurality of first boundary apexes formed between the respective first recesses and protruding radially outward relative to the first recesses ;
The shoulder is
Furthermore, a plurality of second recesses formed at equal intervals in the circumferential direction above the first boundary top in the can axial direction and recessed radially inward;
a plurality of second boundary apexes formed between the respective second recesses and protruding radially outward relative to the second recesses;
When the surface circumscribing the first boundary top and the second boundary top is used as a reference surface,
The first recess has a curved portion that is folded up and down in the can axial direction at the deepest portion of the first recess, which is the deepest position where the vertical distance from the reference surface is the largest, and extends along the circumferential direction. has
the deepest portion of the first recess is located above both end portions in contact with the first boundary top portions formed on both sides in the circumferential direction of the curved portion in the can axial direction;
Each of the second recesses has a curved portion that is folded up and down in the can axial direction at the deepest portion, which is the deepest position of the second recesses where the vertical distance from the reference surface is the largest, and extends along the circumferential direction. The deepest part of the second recess and both ends in contact with the second boundary tops formed on both sides in the circumferential direction of the curved part of the second recess are formed at the same position in the can axial direction. cage,
Each first recess has two first boundary tops formed on both sides in the circumferential direction of the first recess, and one second boundary top formed between these first boundary tops. surrounded by
Each second recess has at least two second boundary tops formed on both sides of the second recess in the circumferential direction, and one first boundary top formed between these second boundary tops. , surrounded by
The shortest distance L1 from the deepest part of the first recess to the top of the second boundary surrounding the first recess is the shortest distance L2 from the deepest part of the second recess to the top of the first boundary surrounding the second recess. A can body characterized by being provided smaller than . 2. The can body according to claim 1 , wherein the deepest portion of the first recess is formed to have a smaller vertical distance from the reference plane than the deepest portion of the second recess. The shoulder further has an upper bent portion that bends radially inward from the upper end of the tapered portion,
The upper bent portion is
an odd number of upper recesses that are formed at equal intervals in the circumferential direction and are recessed radially inward from the reference surface;
a plurality of upper boundary apexes that are formed between the upper recesses, protrude radially outward relative to the upper recesses, and form a part of the reference surface; The can body according to claim 1 or 2 . 4. The method for manufacturing a can body according to any one of claims 1 to 3 , wherein a cylindrical body having a conical shoulder portion is formed continuously from the upper end of the straight body portion, and By moving an annular shoulder forming die from the open end in the can axial direction and pressing the conical shoulder, the conical shoulder is partially plastically deformed to form the first recess and the first recess. 1. A method of manufacturing a can body characterized by forming one bounded top.

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