Metal container and manufacturing method thereof

Abstract

Provided are: a metal container having a shape in which a side wall section having a surface on which a printing process is easily performed can be formed in a sufficient size, and in which the adhesion phenomenon during conveyance in a stacked state can be avoided; and a method for manufacturing a metal container capable of effectively forming such a metal container. This metal container has an opening part, a side wall part, and a bottom part, the outer diameter of the lower end of the metal container is smaller than the inner diameter of the upper end of the metal container, and the metal container has the shape of a bottomed cup formed by drawing a plate-shaped metal material and trimming the plate-shaped metal material. A side wall portion having a tapered profile by performing drawing down is formed on the bottom side of the bottomed cup with respect to the opening portion, a bulging portion bulging in the circumferential direction is formed on the side wall portion, and a continuous tapered surface in which a tapered surface is continuous by performing drawing down a plurality of times is formed on the lower side of the bulging portion.

Description

Technical Field

[0001] The present invention relates to a metal container and a method for manufacturing the same. Background Art

[0002] A metal container made mainly of aluminum, stainless steel, etc. has a storage space for storing contents and an opening for the contents to enter and exit the storage space. The metal container may take the form of a can with an opening sealed with a lid, a cup with an open opening, etc.

[0003] Conventionally, as such a metal container, there is known a tapered metal container (hereinafter also referred to as a "tapered container"). The metal container has an upper opening, a side wall, and a bottom, and has a tapered shape in which the inner diameter of the side wall gradually decreases from the upper opening toward the bottom in such a manner that the outer diameter of the bottom (lower end outer diameter) is smaller than the inner diameter of the opening (upper end inner diameter).

[0004] Such a tapered container is manufactured, for example, by the following manufacturing method: stock material is prepared, a cup is formed by punching and drawing, the cup is further drawn to obtain a cup having a specified height and wall thickness, the cup is then cut to a specified height, the top end of the cup is rounded, and the cup is then drawn to form a plurality of vertical wall sections, and each of the plurality of vertical wall sections is then expanded using a die head to form a side wall portion having a tapered profile (see Patent Document 1 below). Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-142566 Summary of the invention Problems to be solved by the invention

[0006] Moreover, the conical container also has the same requirements as other containers for printing characters and images on its sidewalls. Therefore, it is desirable to form a relatively smooth face that is easy to implement printing processing as a display space in the sidewalls of the conical container with enough sizes.

[0007] On the other hand, the conical containers manufactured by the conventional manufacturing method are transported in a state of being stacked in multiple layers by inserting the bottom of one container into the opening of another container. However, there is a problem that when the conventional metal containers having conical sidewalls are transported in a stacked state, the upper container relatively enters the lower container due to vibration and impact during transport, and it is easy to cause a phenomenon that the stacked containers cannot be easily separated when separated (so-called sticking phenomenon). Therefore, it is ideal that the conical container has a shape that allows it to be easily separated after transport.

[0008] The above-mentioned conventional manufacturing method has the following problems: the steps for forming the side wall portion having a tapered profile are complicated and it is difficult to cope with various shapes. Therefore, it is difficult to easily manufacture a tapered container having a shape that meets the above requirements.

[0009] The present invention has been made in view of the above circumstances, and an example of the subject is to solve the above-mentioned problem. That is, an example of the subject of the present invention is to provide a metal container having a shape as follows: a side wall portion having a surface that is easy to print and having a sufficient size can be formed, and a metal container manufacturing method that can effectively form such a metal container can be avoided when the metal container is transported in a stacked state. Means of solving problems

[0010] The metal container of the present invention comprises an opening, a side wall and a bottom, wherein the outer diameter of the lower end of the metal container is smaller than the inner diameter of the upper end, and the metal container is characterized in that it has the shape of a bottomed cup formed by drawing a plate-shaped metal material and trimming the same, wherein the side wall having a tapered profile by reducing the diameter and drawing is formed on the bottom side of the bottom cup relative to the opening, wherein a bulging portion bulging in the circumferential direction is formed on the side wall, and wherein a continuous tapered surface formed by continuing the tapered surface by performing multiple reducing the diameter and drawing is formed on the lower side relative to the bulging portion.

[0011] The manufacturing method of a metal container of the present invention is a manufacturing method of a metal container having an opening, a side wall and a bottom, and the outer diameter of the lower end is smaller than the inner diameter of the upper end. The manufacturing method of the metal container is characterized in that it has the following steps: forming a bottomed cup by drawing a plate-shaped metal material; trimming the bottomed cup; and performing a diameter reduction drawing on the bottom side of the bottomed cup relative to the opening to form the side wall having a tapered profile, in the step of forming the side wall, a bulging portion bulging in the circumferential direction is formed, and a continuous tapered surface is formed on the lower side of the bulging portion by performing multiple diameter reduction drawing to connect the tapered surfaces. Effects of the Invention

[0012] According to the present invention, a metal container having the following shape and a method for manufacturing a metal container that can effectively form such a metal container can be provided: a side wall portion having a surface of sufficient size to facilitate printing processing can be formed, and a sticking phenomenon can be avoided when transporting in a stacked state. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is an external view showing one form of a metal container in an embodiment of the present invention. Figure 2It is an explanatory diagram showing the steps of the method for manufacturing a metal container in the embodiment of the present invention. Figure 3 The following are explanatory diagrams of the side wall portion forming step (the processing sequence of the step is shown in the order of (a) → (b) → (c)). Figure 4 These are explanatory diagrams of the side wall portion forming step ((b1) to (b6) represent the first to sixth stages). Figure 5 This is an explanatory diagram of a stacked state of metal containers. Figure 6 This is an explanatory diagram showing another example of metal containers in a stacked state. DETAILED DESCRIPTION

[0014] Hereinafter, an embodiment of the present invention (this embodiment) will be described with reference to the drawings. In the following description, the same reference numerals in different drawings represent parts with the same functions, and repeated descriptions in the drawings will be omitted as appropriate.

[0015] An embodiment of the present invention is to manufacture Figure 1 An embodiment of a metal container 1 is shown. Figure 1 The metal container 1 shown has an opening 1A, a side wall 1B and a bottom 1C, and is a cup-shaped container that can replace existing disposable paper cups and plastic cups. Figure 1 In the example, an example is shown in which the opening 1A is provided with a curl 10 bent toward the outside and the opening 1A is used in an open state, but the present invention is not limited thereto, and the opening 1A may be provided with a curved flange for the outer peripheral edge of the cover body to be rolled up and used as a tank container. It should be noted that the "up" and "down" in this specification and the like are based on the state in which the opening 1A is set up and the bottom 1C is set down. Therefore, the "up and down direction" refers to the vertical direction from the opening 1A toward the grounding portion that grounds the bottom 1C.

[0016] Figure 1 The metal container 1 shown has a side wall portion 1B having a tapered profile as a whole so that the outer diameter (lower end outer diameter) of the bottom portion 1C is smaller than the inner diameter (upper end inner diameter) of the opening portion 1A. Thus, a plurality of metal containers 1 can be stacked in a state where the bottom 1C of the upper metal container 1 is placed in the opening portion 1A of the lower metal container 1, and the plurality of metal containers 1 can be stacked and transported when the metal containers 1 are not in use.

[0017] In the metal container 1, the ratio of the inner diameter of the opening 1A (upper end inner diameter) to the outer diameter of the bottom 1C (lower end outer diameter) can be appropriately set according to the use of the metal container 1, and is not particularly limited. For example, it can be set to 1.2:1 to 2:1. For example, when the upper end inner diameter is 80 mm, the lower end outer diameter can be 50 mm.

[0018] Reference Figure 2 Flow chart for manufacturing Figure 1 The process (manufacturing method) of the metal container 1 shown in the figure is described. First, a plate material wound into a coil is cut to prepare a plate material (S0: plate material preparation process), and the plate material is punched, drawn and / or thinned to form a cup-shaped intermediate member (hereinafter, a bottom cup) (S1: cup punching process).

[0019] Next, after the formed bottomed cup is subjected to further drawing and / or thinning and bottom forming as needed (S1' process), the top end of the bottomed cup having a predetermined outer diameter, a predetermined height, and a predetermined plate thickness is trimmed (S2: trimming process). Trimming is a process for uniformly cutting the top end height of the bottomed cup that has become uneven due to further drawing and / or thinning, etc., around the central axis, so that the top end height of the bottomed cup becomes constant after trimming.

[0020] Next, the top end of the cup with a bottom after trimming is subjected to top end diameter reduction drawing (S3: top end diameter reduction drawing process). The diameter reduction drawing process for the top end is a so-called necking process, in which the top end opening of the cup with a bottom is reduced in diameter to form a necking portion n that gradually decreases in diameter toward the top end, and forms a predetermined portion for subsequent curling or flange processing.

[0021] After the top end diameter reduction drawing step S3, an opening having a curl or flange is formed at the top end of the cup with a base (the predetermined portion for curling or flange forming) (S4: opening forming step). By forming a curl or flange at the top end in this way, the rigidity of the top end opening can be improved, and the deterioration of the roundness when the side wall portion 1B is formed in the next step can be suppressed.

[0022] In the formation of the side wall portion 1B after the opening portion forming step S4 (S5: side wall portion forming step), the side wall portion 1B having a tapered profile as a whole is formed by gradually performing diameter reduction drawing on the bottom 1C side of the portion where the top diameter reduction drawing is performed. That is, the side wall portion 1B having a tapered profile as a whole is formed by alternately forming the tapered surface t (inclined wall portion) and the vertical surface s (vertical wall portion) on the bottom 1C side of the necking portion n where the top diameter reduction drawing is performed.

[0023] A continuous tapered surface tm formed by continuous tapered surfaces t is formed near the center of the side wall portion 1B in the vertical direction. The continuous tapered surface tm is the longest tapered surface (the longest inclined wall portion) in the side wall portion 1B. Figure 1As shown in FIG. 1 , when the vertical height H from the grounding portion D to the upper end E of the metal container 1 is set to 100%, the continuous tapered surface tm has a vertical height H1 of at least 20% to 30% of the vertical height H. In the metal container 1, the continuous tapered surface tm having such a vertical height H1 is formed over the entire circumference. Such a continuous tapered surface tm has a size sufficient to be a display space and is a relatively smooth surface that is easy to print.

[0024] Here, an example of the side wall portion forming step S5 is described in detail. Figure 3 As shown in (a), after the top end is reduced in diameter and drawn, the curled portion 10 (or Figure 6 A bottomed cup Cp having an opening portion 1A of a flange 20 is provided, an internal tool 100 is arranged inside the cup Cp, an external tool 200 is arranged on the bottom 1C side of the bottomed cup Cp, and a pressing tool 300 is brought into contact with the bottom 1C of the bottomed cup Cp.

[0025] The inner tool 100 is a cylindrical tool with a diameter smaller than the inner diameter of the bottomed cup Cp. The outer tool 200 has a drawing molding surface 201 on the inner surface thereof for drawing the side wall of the bottomed cup Cp between the outer peripheral surface of the inner tool 100, and an inclined molding surface 202 on the inner surface thereof for molding the side wall of the bottomed cup Cp into an inclined shape. The inclined molding surface 202 of the outer tool 200 has a curved surface (r surface) that is inclined outwardly with respect to the central axis 100P of the inner tool 100.

[0026] In the first stage of the side wall forming step S5, Figure 3 From the state shown in (a), Figure 3 As shown in (b), the external tool 200 is moved relative to the fixed internal tool 100 from the bottom 1C toward the opening 1A in the direction of the arrow in the figure, thereby performing a diameter reduction drawing process on the side wall of the bottom cup Cp, and then the inclined molding surface 202 of the external tool 200 is brought into contact with the bottom 1C side of the necking portion n that has been subjected to the top diameter reduction drawing, thereby forming a tapered surface t. Figure 3 As shown in (c), when the external tool 200 is returned to the bottom 1C side, a bulge 11 consisting of a necking portion n and a tapered surface t is formed on the top end side of the bottom cup Cp and on the bottom 1C side of the curl 10. It should be noted that as a method for forming the bulge 11, for example, the bulge 11 can be formed by a method of making a tool (not shown) contact with the inner surface of the bottom cup Cp to expand in the circumferential direction, a method of forming a step portion on the side wall of the bottom cup Cp by diameter reduction drawing, etc.

[0027] pass Figure 4The next stage in the side wall forming process S5 is described. Compared with the first stage of the diameter reduction drawing process using the internal tool 100 with the tool radius Tr1 in the above description, the second stage of the diameter reduction drawing process is performed on the side wall of the bottom cup Cp using the internal tool 100 with the tool radius Tr2 (Tr1>Tr2). At this time, the inner diameters of the deep drawing molding surface 201 and the inclined molding surface 202 of the external tool 200 are set according to the tool diameter of the internal tool 100.

[0028] In the first stage of the shrinkage and drawing process (refer to Figure 4 In (b1)), the moving stroke St1 of the external tool 200 is the stroke length required to form the tapered surface t of the bulging portion 11. In contrast, in the second stage of the diameter reduction drawing process (refer to Figure 4 In (b2)), the movement stroke St2 of the external tool 200 is made shorter than the movement stroke St1 of the first stage, and a vertical surface s and a tapered surface t connected thereto are formed on the bottom 1C side of the tapered surface t in the bulging portion 11.

[0029] In the next third stage, the diameter reduction and drawing process (refer to Figure 4 In (b3), the internal tool 100 with a tool radius Tr3 (Tr2>Tr3) is used in contrast to the second stage of the reduction drawing process using the internal tool 100 with a tool radius Tr2 in the above description. In addition, in the third stage of the reduction drawing process, the movement stroke St3 of the external tool 200 is made shorter than the movement stroke St2 of the second stage, and a vertical surface s and a tapered surface t connected thereto are formed on the bottom 1C side of the tapered surface t formed by the second stage of the reduction drawing process.

[0030] In these first to third stage diameter reduction drawing processes, an external tool 200 is used in which the curvature radius r of the curved surface (r surface) constituting the inclined forming surface 202 is r1. The inclined forming surface 202 with a curvature radius r1 in the external tool 200 is made to abut against the side wall of the bottom cup Cp to form the side wall into an inclined shape, thereby forming a tapered surface t.

[0031] In contrast, in the following fourth to sixth stages of the shrinkage drawing process (refer to Figure 4 In (b4) to (b6)), the side wall of the bottomed cup Cp is subjected to a diameter reduction drawing process using an external tool 200 in which the curvature radius r of the curved surface constituting the inclined molding surface 202 is a curvature radius r2 that is larger than the curvature radius r1.

[0032] In the fourth stage of the shrinkage and drawing process (refer to Figure 4In (b4), the inner tool 100 with a tool radius Tr4 (Tr3>Tr4) is used to perform the diameter reduction drawing on the side wall of the bottom cup Cp, compared with the third stage of the diameter reduction drawing process using the inner tool 100 with a tool radius Tr3. In the fourth stage of the diameter reduction drawing process, the movement stroke St4 of the external tool 200 is made shorter than the movement stroke St3 of the third stage, and a vertical surface s and a first part of the continuous tapered surface tm connected thereto are formed on the bottom 1C side of the tapered surface t formed by the third stage of the diameter reduction drawing process. The tapered surface tm1 is formed by making the inclined molding surface 202 of the curvature radius r2 in the external tool 200 abut against the side wall of the bottom cup Cp to mold the side wall into an inclined shape.

[0033] In the fifth stage of the shrinkage and drawing process (refer to Figure 4 In (b5)), the side wall of the bottom cup Cp is subjected to the diameter reduction drawing process using the internal tool 100 having the tool radius Tr4 in the fourth stage. The internal tool 100 having the tool radius Tr5 (Tr4>Tr5) is used to perform the diameter reduction drawing process. In the fifth stage of the diameter reduction drawing process, the movement stroke St5 of the external tool 200 is made shorter than the movement stroke St4 in the fourth stage and is close to the movement stroke St4, thereby forming the tapered surface tm2 of the second part of the continuous tapered surface tm on the bottom 1C side of the tapered surface tm1 of the first part of the continuous tapered surface tm formed by the fourth stage of the diameter reduction drawing process. By making the movement stroke St5 close to the movement stroke St4, the tapered surface tm1 and the tapered surface tm2 become continuous tapered surfaces without the vertical surface s in between. The tapered surface tm2 is also formed by making the inclined molding surface 202 of the curvature radius r2 in the external tool 200 abut against the side wall of the bottom cup Cp to mold the side wall into an inclined shape.

[0034] In the sixth stage of the shrinkage and drawing process (refer to Figure 4 In (b6)), the inner tool 100 with a tool radius Tr6 (Tr5>Tr6) is used to perform the diameter reduction drawing on the side wall of the bottom cup Cp, in contrast to the fifth stage of the diameter reduction drawing process using the inner tool 100 with a tool radius Tr5. In the sixth stage of the diameter reduction drawing process, the movement stroke St6 of the external tool 200 is made shorter than the movement stroke St5 of the fifth stage and is close to the movement stroke St5, thereby forming the tapered surface tm3 of the third part of the continuous tapered surface tm on the bottom 1C side of the tapered surface tm2 of the second part of the continuous tapered surface tm formed by the fifth stage of the diameter reduction drawing process. By making the movement stroke St6 close to the movement stroke St5, the tapered surface tm2 and the tapered surface tm3 become continuous tapered surfaces without a vertical surface s in between. The tapered surface tm3 is also formed by causing the inclined molding surface 202 of the curvature radius r2 in the external tool 200 to abut against the side wall of the bottom cup Cp and molding the side wall into an inclined shape.

[0035] In this way, in the fourth to sixth stages of the diameter reduction drawing process, the process of making the inclined forming surface 202 with a curvature radius r2 in the external tool 200 abut against the side wall of the bottom cup Cp to form the side wall into an inclined shape is performed three times in succession, thereby forming a continuous tapered surface tm formed by the tapered surfaces tm1 to tm3 without separating the vertical surface s.

[0036] As mentioned above, in the fourth to sixth stages of the diameter reduction drawing process (refer to Figure 4 In (b4) to (b6)), an external tool 200 is used in which the curvature radius r of the inclined molding surface 202 (curved surface) is a curvature radius r2 that is larger than the curvature radius r1. Therefore, the lengths of the tapered surfaces tm1 to tm3 formed by the inclined molding surface 202 with the curvature radius r2 in the inclined direction from the opening 1A to the bottom 1C are all longer than the tapered surface t formed by the inclined molding surface 202 (curved surface) with the curvature radius r1. The continuous tapered surface tm formed by the continuous tapered surfaces tm1 to tm3 becomes the tapered surface (the longest inclined wall portion) with the longest length in the inclined direction from the opening 1A to the bottom 1C.

[0037] As described above, in the diameter reduction drawing process of the present embodiment, when forming the continuous tapered surface tm, by using the external tool 200 having the inclined molding surface 202 (curved surface) with a relatively large radius of curvature r2, a sufficiently large continuous tapered surface tm can be formed with a small number of diameter reduction drawing processes, such as three times in the fourth to sixth stages. In addition, such a continuous tapered surface tm has a size sufficient to be a display space and is a relatively smooth surface that is easy to perform printing processing.

[0038] The continuous tapered surface tm can also be formed by using an external tool 200 having an inclined molding surface 202 (curved surface) with a curvature radius r1 in the same manner as when forming the tapered surface t. However, in this case, the number of diameter reduction drawing steps required to form a sufficiently large continuous tapered surface tm becomes very large, and the manufacturing cost also increases.

[0039] The radius of curvature r1 is not particularly limited as long as it is a value smaller than the radius of curvature r2, and can be set to 5 mm to 20 mm, for example. The radius of curvature r2 is preferably 20 mm to 100 mm, and can be set to r2 = 60 mm (also referred to as r2 = 60r). If the radius of curvature r1 is smaller than the value within the specified range, it is difficult to form a specified taper angle. On the contrary, if the radius of curvature r1 is larger than the value within the specified range, wrinkles are easily generated on the side wall.

[0040] Here, the pitch Pt of the external tool 200 is described. Figure 4The center point of the moving direction (the direction parallel to the central axis 100P) in the inclined forming surface 202 (curved surface) when forming the conical surface t of the bulging portion 11 shown in (b1) is set as p11. In addition, in Figure 4 The center point of the moving direction (the direction parallel to the central axis 100P) in the inclined forming surface 202 (curved surface) when forming the conical surface t on the bottom 1C side of the vertical surface s connected to the bulging portion 11 shown in (b2) is set as p12. And when perpendicular lines are respectively extended from this center point p11 and the center point p12 to the central axis 100P of the internal tool 100, the distance between these two perpendicular lines is set as the pitch pt1.

[0041] In addition, when forming Figure 4 The center point of the moving direction (the direction parallel to the central axis 100P) in the inclined forming surface 202 (curved surface) when forming the first part conical surface tm1 of the continuous conical surface tm of the bulging portion 11 shown in (b4) is set as p21. In addition, when forming Figure 4 The center point of the moving direction (the direction parallel to the central axis 100P) in the inclined forming surface 202 (curved surface) when forming the second part conical surface tm2 of the continuous conical surface tm shown in (b5) is set as p22. And when perpendicular lines are respectively extended from this center point p21 and the center point p22 to the central axis 100P of the internal tool 100, the distance between these two perpendicular lines is set as the pitch pt2.

[0042] In this case, the magnitude relationship between the pitch pt1 and the pitch pt2 can be pt2 < pt1. The pitch pt1 is not particularly limited. For example, it can be set to 5 mm to 15 mm. The pitch pt2 is preferably 3 mm to 10 mm. For example, it can be set that pt1 = 10 mm and pt2 = 8 mm. If the pitch pt1 and the pitch pt2 are small, it is easy to impart the desired shape, but the forming time increases and the forming device becomes larger. On the other hand, if the pitch pt1 and the pitch pt2 are large, the forming time decreases and the forming device can be made compact, but the shape that can be imparted is limited.

[0043] In the ironing process after the seventh stage following the ironing process in the sixth stage (not shown), the outer tool 200 having an inclined forming surface 202 (curved surface) with a radius of curvature r1 is used again to perform ironing on the side wall of the bottomed cup Cp. In the ironing process after the seventh stage (not shown), the tool radius of the internal tool 100 is made smaller than that of the previous stage, and the moving stroke of the outer tool 200 is made shorter than that of the previous stage, and the same processes as those in the ironing processes in the second stage and the third stage are repeated. Thus, a vertical surface s and a conical surface t are alternately formed on the bottom 1C side of the third part conical surface tm3 in the continuous conical surface tm formed by the ironing process in the sixth stage.

[0044] Through such a shrinkage and drawing process, a Figure 1 The side wall portion 1B shown in FIG. In the side wall portion 1B, tapered surfaces t and vertical surfaces s are repeatedly and alternately formed below the bulging portion 11, and a continuous tapered surface tm is formed near the center in the vertical direction, and the side wall portion 1B has a tapered profile as a whole.

[0045] In the second and subsequent stages of the diameter reduction drawing process, the inner surface of the curl 10 is arranged to contact the outer surface of the inner tool 100 (see Figure 4 (b2)). This is to prevent the curl 10 (mouth) from becoming elliptical, thereby preventing the metal containers 1 from sticking when stacking.

[0046] Figure 1 The metal container 1 shown in the figure has a bulging portion 11 on the lower side of the opening 1A having the curl 10, so that in the stacked state, as shown in FIG. Figure 5 As shown, the inner surface contact portion F2 in the inner surface of the opening portion 1A of the lower metal container 1 (bottom) is in contact with the outer surface contact portion F1 in the outer surface of the side wall portion 1B of the upper metal container 1 (top) and is stacked, and in one metal container 1, the above-mentioned bulge 11 is formed between the outer surface contact portion F1 and the inner surface contact portion F2.

[0047] As for the bulging portion 11, Figure 5 As shown, in a metal container 1, the maximum width between the perpendicular line Lp connecting the outer surface contact part F1 and the inner surface contact part F2 and the outer surface of the bulge 11 is defined as the hook width f. In addition, the angle of the tapered surface t toward the outer surface contact part F1 relative to the perpendicular line Lp is defined as the inclination angle α.

[0048] In order to avoid the above-mentioned sticking phenomenon, the hook width f is preferably 0.3 mm or more, more preferably 0.8 mm or more. If the hook width f is smaller than this, the opening 1A is easy to bite into the bulging portion 11, and if it is subjected to vibration and impact during transportation in a stacked state, the bite is easy to become larger, and the above-mentioned sticking phenomenon is easy to occur.

[0049] As a factor determining the upper limit of the hook width f, there is an outer diameter R11 of the bulge 11 including the hook width f. The outer diameter R11 of the bulge 11 is preferably smaller than the outer diameter R10 of the curl 10 (opening 1A). If the outer diameter R11 of the bulge 11 is larger than the outer diameter R10 of the curl 10, when the metal container 1 is arranged and stored in the horizontal direction, the bulge 11 will be in a state of protruding in the horizontal direction from the curl 10, thereby increasing the storage space by the protruding amount and reducing the storage efficiency.

[0050] In addition, in order to avoid the sticking phenomenon, it is preferred to set the inclination angle α to a range of 10° to 50°. If the inclination angle α becomes smaller, the same situation as the case of reducing the above-mentioned hook width f will occur. In addition, the friction resistance when pulling apart from the stacked state becomes larger, so it is easy to cause the sticking phenomenon. It should be noted that the hook width f and the inclination angle α are adjustment factors that are related to each other. By combining the conditions of the two, the avoidance measures for the sticking phenomenon will become more effective.

[0051] Furthermore, in the stacked state of the metal container 1, as Figure 5 As shown in FIG. 1 , the distance between the upper end of the opening 1A in the upper metal container 1 (top) and the upper end of the opening 1A in the lower metal container 1 (bottom) is the stacking height hs. The stacking height hs affects the storage space in the height direction in the stacked state. By further reducing the stacking height hs, the storage efficiency in the height direction in the stacked state of the metal containers 1 is improved.

[0052] As mentioned above, Figure 1 The side wall 1B of the metal container 1 shown includes a bulging portion 11, and vertical surfaces s and tapered surfaces t are alternately formed, so that the side wall 1B has a tapered profile as a whole. In addition, a continuous tapered surface tm (longest inclined wall portion) having the longest length of the tapered surface t is formed near the center of the side wall 1B in the vertical direction.

[0053] In this way, by alternately forming the vertical surface s and the tapered surface t on the side wall portion 1B, when the metal container 1 is used as a cup for beverages, the step formed by the vertical surface s and the tapered surface t functions as an anti-slip member when the metal container 1 is held by hand. In addition, the continuous tapered surface tm near the center of the side wall portion 1B can be effectively used as a display space by including a printing process for printing an image or the like thereon.

[0054] Aluminum, aluminum alloy, stainless steel, steel, etc. can be used as the material constituting the base material of the metal container 1. However, by using aluminum, aluminum alloy, or steel, a metal container 1 suitable for a beverage container can be obtained which is lightweight, has a good appearance due to its gloss, and allows the temperature of the contents (e.g., cold water) to be easily felt by hand. In addition, as the material of the metal container 1, a plate-shaped metal material can be used in which a single-layer or multi-layer PET film or other resin film is coated on both sides of a base material of aluminum, aluminum alloy, or steel.

[0055] When such a resin-coated substrate is used, it is preferable to provide a step of locally heating the portion to be processed with the curl or flange as a Figure 2The process of forming the opening of the curl or flange S4 shown in the figure is a pre-process. The local heating is performed by, for example, high-frequency heating, and the processing predetermined portion of the necking portion n near the top end is locally heated at a target temperature of 200°C±30°C. By performing such local heating, the adhesion between the substrate and the applied resin can be improved, and the resin film can be prevented from peeling off from the substrate when processing the curl or flange, so that good processing quality can be obtained.

[0056] It should be noted that the opening 1A of the metal container 1 is formed as follows Figure 6 In the case of the flange 20 shown, the flange 20 becomes a portion for rolling up the outer edge of the cover body. By rolling up the cover body, the metal container 1 becomes a can body that seals the contents. Here, the rolled-up cover body is a metal cover body, for example, a partially open end (POE: Partial Open End) can cover of a pull ring type or a retention pull ring type, a fully open end (FOE: Full Open End) can cover, etc., but it can also be a cover body of other forms. In addition, it is also possible to use an opening portion 1A of other forms instead of the flange 20, and in contrast, a cover body of other forms such as a threaded cap is attached to the opening portion 1A in a manner that can be easily installed and removed.

[0057] In addition, as described above, when a substrate coated with a resin is used as the plate-shaped metal material, no lubricant (coolant) is required in the side wall portion forming step S5. Thus, a manufacturing method can be realized in which no cleaning step is provided between or after a series of steps. Thus, a high-productivity manufacturing can be performed by omitting the cleaning and drying steps, and by eliminating the waste of lubricants, etc., a manufacturing that is also favorable in terms of the environment can be performed.

[0058] In addition, the inclined molding surface 202 of the external tool 200 is not limited to the curved surface as described above, and may be other shapes, for example, a conical surface (not shown) inclined outwardly with respect to the central axis 100P of the internal tool 100. In the case where the inclined molding surface 202 is such a conical surface, it is preferred that the inclined molding surface 202 (conical surface) of the external tool 200 used in the fourth to sixth diameter reduction drawing processes for forming the continuous tapered surface tm has a longer length in the inclined direction than the external tool 200 used in the first to third diameter reduction drawing processes for forming the tapered surface t. Thus, as described above, a sufficiently large continuous tapered surface tm can be formed with a small number of diameter reduction drawing processes.

[0059] As described above, in the manufacturing method of the metal container 1 of the present embodiment, the side wall portion 1B is formed by the diameter reduction drawing from the bottom 1C side, thereby being able to cope with a variety of shapes. In the manufacturing method of the metal container 1, in the formation of the side wall portion 1B, a bulging portion 11 that bulges in the circumferential direction is formed, and a continuous tapered surface tm formed by continuous tapered surfaces t by performing multiple diameter reduction drawing is formed below the bulging portion 11. In this way, according to the manufacturing method of the metal container 1, a metal container 1 can be manufactured that can form a side wall portion 1B with a surface that is easy to print in a sufficient size and can effectively form a container with a shape that can avoid the sticking phenomenon when transported in a stacked state.

[0060] The embodiments of the present invention are described in detail with reference to the accompanying drawings, but the specific configuration is not limited to these embodiments, and even if there are changes in the design within the scope of the present invention, they are also included in the present invention. In addition, as long as there are no special contradictions or problems in the purpose and configuration of the examples, the techniques can be combined with each other. Description of Reference Numerals

[0061] 1: metal container; 1A: opening; 1B: side wall; 1C: bottom; 10: curling; 11: bulging; 20: flange; 100: internal tool; 100P: center axis; 200: external tool; 201: drawing surface; 202: inclined surface; 300: pressing tool; t: tapered surface; tm: continuous tapered surface; s: vertical surface; n: necking; S0: sheet metal material preparation process; S1: cupping process; S2: trimming process; S3: top end reduction drawing process; S4: opening forming process; S5: side wall forming process; St1~St6: moving stroke; Tr1~Tr6: tool radius; Cp: cup with bottom; F1: outer surface contact part; F2: inner surface contact part; r, r1, r2: curvature radius; R10: outer diameter of opening 1A; R11: outer diameter of bulging part 11.

Claims

1. A metal container, comprising an opening, a side wall and a bottom, wherein the outer diameter of the lower end of the metal container is smaller than the inner diameter of the upper end, and wherein the metal container is characterized in that: It has the shape of a bottomed cup formed by drawing a plate-shaped metal material and trimming it. The side wall portion having a tapered profile by performing diameter reduction drawing is formed on the bottom side of the bottom cup relative to the opening. The side wall portion has a bulging portion bulging in the circumferential direction, and a continuous tapered surface formed by continuously performing a plurality of diameter reduction drawing operations on the lower side of the bulging portion.

2. A method for manufacturing a metal container, the metal container having an opening, a side wall and a bottom, wherein the outer diameter of the lower end of the metal container is smaller than the inner diameter of the upper end, the method for manufacturing the metal container comprising the following steps: A cup with a bottom is formed by deep drawing a sheet metal material; Performing trimming processing on the cup with a bottom; and The bottom cup is subjected to diameter reduction drawing on the bottom side of the bottom portion relative to the opening portion to form the side wall portion having a tapered profile. In the step of forming the side wall portion, a bulging portion bulging in the circumferential direction is formed, and a continuous tapered surface formed by continuously performing a plurality of diameter reduction drawing operations on a lower side of the bulging portion is formed.

3. The method for manufacturing a metal container according to claim 2, characterized in that: When a vertical height H from the grounding portion to the upper end of the metal container is assumed to be 100%, the continuous tapered surface has a vertical height H1 of at least 20% to 30% relative to the vertical height H.

4. The method for manufacturing a metal container according to claim 2, characterized in that: The method includes the step of forming the opening portion with a curl or a flange.

5. The method for manufacturing a metal container according to claim 2, characterized in that: The ratio of the upper inner diameter to the lower outer diameter of the metal container is 1.2:1 to 2:

1.

6. The method for manufacturing a metal container according to claim 2, characterized in that: The tapered surface and the continuous tapered surface are formed by diameter reduction drawing using an external tool having a curved surface, and the curvature radius of the curved surface of the external tool forming the continuous tapered surface is larger than the curvature radius of the curved surface of the external tool forming the tapered surface.

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