JP4116011B2 - Manufacturing method of square can - Google Patents

Description

The present invention relates to a process for the preparation of Sumikan used as such packaging containers.

  Conventionally, this type of square can consists of a can body and a can lid, and the can lid is formed by drawing one plate material. The can manufacturing method is roughly classified into a one-piece type using one plate material and a two-piece type using two plate materials.

  As a one-piece type manufacturing method, for example, as disclosed in Patent Document 1, square notches are formed at the four corners of a rectangular plate by cutting, and a space between two adjacent notches is formed. While cutting each part as a side wall at a right angle while bending the ends of adjacent side walls to each other, a rectangular plate material is folded at a right angle with the four sides of each side as a side wall, and at the four corners of the plate material There is a folding type in which each folding portion is provided, and each folding portion is folded into a triangle and crimped to the inner surface of the side wall.

In addition, the two-piece type manufacturing method bends a belt-like plate material at three or four points at a right angle and joins both ends thereof by winding or welding to form a square cylindrical can body. A rectangular bottom plate corresponding to the trunk is prepared. And the lower edge part of a can body and the peripheral part of a baseplate are wound up doubly outside, and a can body is comprised. In addition, the double winding structure of the lower edge part of a can body and the peripheral part of a bottom plate is disclosed by patent document 2, for example.
JP-A-6-321235 Japanese Patent No. 2915898 (page 3, FIG. 6)

  However, in the conventional manufacturing method described above, in the one-piece type, in the case of the cutting method, the portion that is cut to form the missing portion becomes a material loss, and in the case of the folding method, the folded portion becomes a material loss. Therefore, the manufacturing cost is increased accordingly. Moreover, the surface of a side wall and the surface of a bottom part cannot be painted separately, but there also exists a fault that it receives restrictions on design.

  On the other hand, in the case of the two-piece type, since the structure in which the lower edge portion of the can body and the peripheral edge portion of the bottom plate are double-wrapped outward is adopted, the corner portion of the can body has a curved shape, It cannot be made into the shape where adjacent side walls orthogonally cross like the one-piece type. For this reason, there is a drawback in that the angular feeling as a square can cannot be sufficiently exhibited, and the volume of the square can is reduced.

The present invention has been made in view of such various points, and the subject of the present invention is, in particular, a winding structure or winding between the lower edge of the can body and the peripheral edge of the bottom plate in the conventional two-piece type manufacturing method. By improving the fastening method and making the corners of the can body into a shape in which the adjacent side walls are orthogonal to each other, such as a one-piece type, the angular effect as a square can is fully manifested and a design effect It is intended to provide a method of manufacturing a square can that can increase the volume of the square can , increase the volume of the square can , eliminate the material loss, reduce the manufacturing cost, and eliminate the design constraints.

In order to solve the above-mentioned problems, the invention according to claim 1 is a method for manufacturing a square can obtained by tightening a lower edge portion of a rectangular tube-shaped can body and a peripheral edge portion of a bottom plate. The lower part is formed with a folded part formed by folding the lower edge inward in a substantially U-shaped cross section, while the first bent part that bends obliquely upward at the peripheral part of the bottom plate and the lower part outside the tip of the first bent part A step of forming a second bent portion that bends to the bottom of the can, and a step of fitting a bottom plate into the can body while the second bent portion is engaged between the lower edge portion of the can body and the folded portion. Using a pressing device having an upper mold, a movable mold that holds the bottom portion between the lower mold and a pressing mold that presses the movable mold and moves horizontally, the bottom plate is pulled to the peripheral side. The lower edge of the can body, the second bent part of the bottom plate and the can body To the to portion and the first bent portion of the bottom plate to the structure and a step of bonding together.

  In this configuration, when winding the lower edge portion of the rectangular tube-shaped can body and the peripheral edge portion of the bottom plate, the lower end portion of the can body and the second bent portion of the bottom plate are expanded while pulling the bottom plate to the peripheral edge side. By joining the folded portion of the can body and the first bent portion of the bottom plate to each other, the corners of the can body are adjacent to each other at right angles as in the one-piece type while ensuring the sealing performance at the tightening portion. Can be an angular shape.

  The invention according to claim 2 includes a step of forming rounded curved portions at the upper end and the lower end of each corner portion of the can body in order to cope with the angular shape of the can body. Further, a configuration is provided. With this configuration, it is possible to prevent a finger from being caught at the corner of the can body.

As described above, according to the manufacturing method of the Sumikan in the present invention, the can Upon tightening winding a peripheral portion of the lower edge and the bottom plate of the square tube-shaped can body, while expanding to pull the bottom plate to the peripheral edge The lower edge of the barrel, the second bent portion of the bottom plate, the folded portion of the can barrel, and the first bent portion of the bottom plate are joined to each other, so that the corner of the can barrel is secured while ensuring the sealing performance at the winding portion. Can be formed into an angular shape in which adjacent side walls are orthogonal to each other like a one-piece type, so that the design effect can be enhanced and the volume of the square can as a container can be increased. In addition, material loss can be reduced, manufacturing costs can be reduced, etc., and the can body and bottom plate can be painted separately in a flat state, eliminating design restrictions and improving design effects. Can be increased.

  In particular, in the invention according to claim 2, it is possible to prevent a finger from being caught at the corners of the can body by forming rounded curved portions at the upper and lower ends of each corner of the can body. It is possible to improve safety.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that are the best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows a can body 1 of a square can according to an embodiment of the present invention. The can body 1 is a box-shaped one having an open top surface, and the top surface opening 1a of the can body 1 is covered with a lid (not shown).

  The can body 1 is formed by winding a lower edge portion of a square cylindrical can body 3 constituting the four side walls 2, 2,... And a peripheral edge portion of a rectangular bottom plate 4 constituting the bottom portion. Both the trunk 3 and the bottom plate 4 are made of a metal plate such as a tin plate. The can body 3 is formed by bending a strip-shaped plate material at a right angle at three locations and joining both ends of the plate material by winding.

  As shown in an enlarged detail in FIG. 5B, a lower edge folded portion 31 formed by folding the lower edge inward in a substantially U-shaped cross section is formed on the lower edge portion of the can body 3 over the entire circumference. On the other hand, a first bent portion 41 that bends upward and a second bent portion 42 that bends outward from the front end of the first bent portion 41 lie over the entire circumference at the peripheral edge of the bottom plate 4. Is formed. Then, the bottom plate 4 is fitted into the can body 3 in a state where the second bent portion 42 is engaged between the lower edge portion of the can body 3 and the lower edge folded portion 31, and the bottom plate 4 is attached to the bottom plate 4. The lower edge portion of the can body 3, the second bent portion 42 of the bottom plate 4, the lower edge folded portion 31 of the can body 3, and the first bent portion 41 of the bottom plate 4 are joined together and wound while being expanded by pulling to the peripheral side. It is tightened.

  In addition, the upper edge portion of the can body 3 is formed with an upper edge folded portion 32 formed by folding the upper edge of the can body 3 in a circular shape over the entire circumference. 3a, 3a,... Are formed with rounded curved portions 33 and 34 at the upper and lower ends, respectively.

  Next, the manufacturing method of the can body 1 will be described with reference to FIGS. 2 to 5. First, a strip-shaped metal plate 30 for forming the can body 3 and a rectangular metal plate material are used. A bottom plate 4 is prepared (see FIG. 2A).

  Subsequently, the belt-shaped metal plate 30 is bent inward at right angles at three points in the middle portion in the longitudinal direction, and both ends of the metal plate 30 are joined together by winding to form a rectangular cylindrical can body 3 is formed. Thereafter, a lower edge folding portion 31 formed by folding the lower edge inwardly in a substantially U-shaped cross section as shown in an enlarged detail in FIG. On the other hand, a first bent portion 41 that is bent obliquely upward as shown in an enlarged detail in FIG. 4 and a second bent bent outwardly from the tip of the first bent portion 41 at the periphery of the bottom plate 40 as shown in FIG. The bent portion 42 is formed over the entire circumference (see FIG. 2B).

  After that, as shown in FIG. 5A, the bottom plate is placed in the can body 3 with the second bent portion 42 engaged between the lower edge portion of the can body 3 and the lower edge folded portion 31. 4 is inserted (see FIG. 2C).

  Subsequently, as shown in FIG. 2 (d), the can body 3 into which the bottom plate 4 is fitted is disposed in the lower die 51 of the press device with the bottom plate 4 facing downward, and then the movable dies 52, 52 of the press device. 5 is placed on the bottom plate 4, and the movable dies 52, 52 are moved outwardly by the pressing dies 53 of the pressing device, thereby pulling the bottom plate 4 to the peripheral side and expanding it, as shown in FIG. As shown in b), the lower edge of the can body 3, the second bent portion 41 of the bottom plate 4, the lower edge folded portion 31 of the can body 3, and the first bent portion 41 of the bottom plate 4 are joined together. At this time, a rounded curved portion 34 is formed at the lower end of each corner portion 3 a of the can body 3 by the mold surface of the lower die 51.

  Thereafter, an upper edge folded portion 32 formed by pressing the upper edge of the can body 3 into a circular shape is formed on the upper edge portion of the can body 3 over the entire circumference by pressing or the like, and each corner portion 3a of the can body 3 is formed. A rounded curved portion 33 is formed at the upper end of the. The can body 1 of a square can is manufactured by the above. In addition, the can lid of a square can is manufactured by press work as usual.

  Accordingly, when the lower edge portion of the rectangular cylindrical can body 3 and the peripheral edge portion of the rectangular bottom plate 4 are tightened in this way, the lower edge of the can body 3 is substantially U-shaped on the inner side. The first bent portion 41 that is bent obliquely upward at the peripheral edge of the bottom plate 4 and the second bent portion 42 that is bent outwardly from the tip of the first bent portion 41 are formed. After the bottom plate 4 is fitted into the can body 3 in a state where the second bent portion 42 is engaged between the lower edge portion of the can body 3 and the lower edge folded portion 31, the bottom plate 4 is The lower edge of the can body 3, the second bent portion 42 of the bottom plate 4, the lower edge folded portion 31 of the can body 3, and the first bent portion 42 of the bottom plate 4 are joined together while being expanded by pulling to the peripheral side. Ensures the same level of tightness as the double-tightened structure. While, it is possible to angular shape adjacent sidewalls 2,2 each other as those of the one-piece type corner 3a of the can body 3 are orthogonal. For this reason, while being able to fully show the angular feeling as the can body 1 of a square can and to enhance the design effect, the volume of the square can as a container can be increased. In addition, there is almost no material loss as in the case of the one-piece type, the manufacturing cost can be reduced, and the can body 3 and the bottom plate 4 can be separately coated in a flat plate state. The design effect can be further improved by eliminating the design restrictions.

  In addition, in the above embodiment, the curved portions 33 and 34 that are rounded are formed at the upper end and the lower end of each corner portion 3a of the can body 3, so that a finger is caught by the corner portion 3a of the can body 3 and the like. Can be prevented, and safety can be improved.

  In addition, this invention is not limited to the said embodiment, Other various embodiment is included. For example, in the above embodiment, in forming the rectangular cylindrical can body 3, the belt-like plate material 30 is bent inward at right angles at three points in the longitudinal direction, and both ends of the plate material 30 are wound together. Although one corner portion 3a is formed by this tightening portion, the present invention is not limited to this. For example, the belt-like plate material 30 is bent inward at four points in the middle portion in the longitudinal direction at right angles, and the plate material. You may make it join the both ends of 30 by welding.

  Moreover, in the said embodiment, although the case where the can body 3 of a square can was a thing of a square cylinder shape was described, this invention has a triangular cylinder shape, a pentagonal cylinder shape, or a hexagonal cylinder shape as this can body shape. This is effective for producing an angular feeling at the corner of the can body.

The can body of the square can which concerns on embodiment of this invention is shown, (a) is the top view which cut in part, (b) is the front view which cut out the left half part. It is process drawing which shows the manufacturing method of the said square can. It is an expanded sectional view of the lower edge part of a can body. It is an expanded sectional view of the peripheral part of a baseplate. It is an expanded sectional view which shows the state before and behind winding of the lower edge part of a can body, and the peripheral part of a baseplate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Can body 3 Can trunk | drum 3a Corner | angular part 4 Bottom plate 31 Lower edge folding | returning part 33,34 Curved part 41 1st bending part 42 2nd bending part

Claims (2)

A method of manufacturing a square can by winding and tightening a lower edge of a rectangular tube-shaped can body and a peripheral edge of a bottom plate,
On the lower edge of the can body is formed a folded portion formed by folding the lower edge inward in a substantially U-shaped cross section, while the first bent portion and the first bent portion are bent obliquely upward at the peripheral edge of the bottom plate. Forming a second bent portion that bends outward from the tip of
A step of fitting a bottom plate into the can body with the second bent portion engaged between the lower edge of the can body and the folded portion;
As the upper mold, using a pressing device having a movable mold that sandwiches the bottom portion between the lower mold and a pressing mold that presses the movable mold and moves horizontally, the bottom plate is pulled to the peripheral side and enlarged. A method for manufacturing a rectangular can comprising: a step of joining the lower edge portion of the can body, the second bent portion of the bottom plate, the folded portion of the can body, and the first bent portion of the bottom plate to each other.   The manufacturing method of the square can of Claim 1 further equipped with the process of forming the rounded curved part in the upper end and lower end of each corner | angular part of the said can body, respectively.

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