JP2008132522A - Metallic can body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a can body of aluminum for beverage having a diameter-reduced neck part, which can body has required strength, has favorable machining suitability for necking and flanging, and has excellent dent resistance, while achieving weight reduction by thinning its wall to the utmost. <P>SOLUTION: A raw can body 1a before necking is formed as follows: a corresponding forming region 40 to be a neck shoulder part 4 of a can body 1 is formed into a convex increased-wall part 41; and a neck part forming region 20, which is located between a flange part forming region 50 at the upper edge, consisting of a maximum wall-thickness part 51, and a neck shoulder forming region 40, is composed of a gradually decreased wall-thickness part 21, whose inner surface is tapered, and a medium wall-thickness part 22. Then, by necking and flanging the raw can body 1a, the can body 1 having a corresponding distribution of wall-thickness is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a metal can barrel such as an aluminum can for beverages used as a container for soft drinks such as alcoholic beverages such as beer, carbonated beverages, juices, etc., especially necking processing at the open end above the can barrel It is related with the metal can cylinder which has a diameter-reduced neck part by which the diameter of the can was reduced step by step toward the upper part, and its manufacturing method.

  The can body of a two-piece can used for beverage aluminum cans is formed from a flat plate into a bottomed cylindrical container by deep drawing and ironing called DI processing. That is, a circular blank punched out of an aluminum coil is drawn into a shallow cup shape with a coupling press, and then the cup is formed into a bottomed cylindrical shape by squeezing the side wall by DI processing. Has been.

  In these aluminum cans for beverages, weight reduction for cost reduction is an important issue, and as one means, so-called necking processing is applied to reduce the diameter of the open end of the can body, and currently there is a four-stage neck. Cans and smooth neck cans are mainstream.

  That is, as shown in FIG. 4A, the can body (1) is roughly divided into a reduced diameter neck portion (2), a side wall portion (3), and a bottom portion (6). However, the neck portion (2) is a portion in which the diameter is gradually reduced from the outer diameter of the can body as shown in the part (B) of the figure, and the can area can be reduced by reducing the required area of the can lid. We are trying to reduce the weight of the lid, and thus the aluminum can for beverages.

At the time of performing the above necking process, as shown in FIG. 4 (C), a can body seat at the time of the necking process is used as a can body element (1a) having a bottomed cylindrical body before the necking process. In order to prevent bending deformation and to prevent occurrence of flange cracking at the time of flange processing for forming the flange portion (5) at the tip, an opening end portion above the formation region (2a) of the neck portion (2) The thickness (T ₁ ) of the film is formed to be thicker than the thickness (T ₂ ) of the formation region (3a) of the side wall (3).

  However, when multiple stages of necking are applied to the can body element (1a) that is formed with a uniform thickness at the open end (12), it is possible to prevent buckling deformation and flange cracking of the can body. Although the thick part of the opening end before necking becomes thicker toward the opening end due to necking, not only is the neck part likely to wrinkle, but there is also a useless increase in thickness. Has a negative effect on the demand for weight reduction.

As a method for improving the above problem, as disclosed in the following Patent Document 1, the lower end portion of the opening end portion of the can body is a thick portion, and the flange forming portion extends from the thick portion toward the opening end portion. Alternatively, a thin portion having a thickness that is gradually reduced except for the vicinity thereof is formed, and a reduced diameter portion that is smaller in diameter than the can body diameter is formed by performing a narrowing process that gradually reduces the diameter from the thin portion toward the flange forming portion. A method for manufacturing a can body has been proposed.
JP-A 63-52721

  However, the product necked by this proposed method has a great effect in that it can reduce the cost by reducing the weight because an excessively thick portion is not formed at the opening end portion like the conventional product. In the can body after necking, the thickness of the necks of the multiple steps is almost uniform, so the can body is difficult to withstand the presser pressure (vertical load) when filling the can body container with beverage. The problem of showing a tendency to bend easily occurs. Furthermore, since the lower part of the flange forming part is formed in the thinnest part as the can body before the necking process, a steep step and a tapered part are formed toward the flange forming part. There is a risk that distortion may occur in the slab, and necking may be hindered.

  The present invention prevents buckling deformation and flange cracking of the can body in necking, and reduces unnecessary wall thickness and maximizes weight reduction without causing wrinkles in the neck. An object of the present invention is to provide a manufacturing method of a metal can body that can be obtained, and to provide a metal can body that is excellent in dent resistance in a neck shoulder portion.

  The present invention presents the following configurations [1] to [5] as means for solving the above problems.

[1] In a method for manufacturing a metal can body having a flange portion and a plurality of reduced diameter neck portions following the flange portion at an upper opening end portion of the bottomed cylindrical can body,
As the thickness of the bottomed cylindrical can body element before processing to form the flange part and the neck part,
a, configure the flange forming area to the maximum thickness part,
b, a reduced diameter neck portion formation region below the first tapered portion with a tapered inner surface where the thickness gradually decreases downward from the thick portion, and an intermediate thick portion having a uniform thickness following the first tapered portion. And consists of
c. A neck shoulder portion forming region extending from the lower end portion of the neck portion forming region to the upper end portion of the straight can barrel side wall forming region is bulged inwardly in a cross-sectional shape in addition to the thickness corresponding to the intermediate thick portion. While configuring the convex thickening portion for dent measures having a thickness less than the maximum thickness portion,
d, and further, the transition region from the neck shoulder portion forming region to the thin side wall main portion forming region of the can body side wall is configured to be an inner tapered second reduced thickness portion,
A method for manufacturing a metal can body, characterized in that necking processing and flange processing are performed on the can body base can.

[2] The thickness of the maximum thickness portion of the flange portion formation region is set in a range of 0.15 to 0.18 mm,
The thickness of the intermediate thick part in the reduced diameter neck part forming region is set in a range of 0.12 to 0.16 mm,
The thickness of the top maximum thickness portion of the convex thickening portion of the neck shoulder portion forming region is set in a range of 0.13 to 0.18 mm,
Furthermore, the thickness of the thin-walled main portion forming region on the side wall of the can body is set in a range of 0.10 to 0.12 mm.
A method for producing a metal can body as described in [1] above.

[3] An inclination angle with respect to the axis of the inner tapered portion in the first thickness gradually decreasing portion is set in a range of 1 to 25 minutes,
The method for manufacturing a metal can body according to the preceding item [1] or [2], wherein an inclination angle of the inner wall tapered portion of the second wall thickness gradually decreasing portion with respect to the axis is set in a range of 10 minutes to 30 minutes.

[4] In a metal can body having a flange portion and a plurality of reduced diameter neck portions following the flange portion at an upper opening end portion of the bottomed cylindrical can body,
The upper flange part is composed of the maximum thickness part,
The diameter-reduced neck portion that continues below this is formed into a gradually increasing thickness portion that is relatively thinner than the flange portion and that gradually increases in thickness from the bottom to the top,
The neck shoulder portion spanning from the lower end portion of the neck portion to the upper end portion of the straight can barrel side wall portion is configured to be a thickened portion that is equal to or less than the thickness of the flange portion and larger than the thickness of the lower end portion of the neck portion,
Furthermore, the metal main body except the thin-wall main part except the upper end part of a can body side wall is comprised by the thin part of the minimum thickness.

[5] A thickness of the flange portion is in a range of 0.16 to 0.19 mm,
The wall thickness of the reduced diameter neck portion is changed in the range of 0.13 to 0.19 mm,
The wall thickness of the neck shoulder is in the range of 0.13 to 0.18 mm,
The thickness of the thin-walled main portion of the can barrel side wall is in the range of 0.10 to 0.12 mm.
The metal can body described in the preceding item [4].

  The invention described in the above item [1] relates to a method for manufacturing a metal can barrel, and has a bottomed cylindrical can barrel before forming a flange portion and a reduced-diameter neck portion at an upper opening end of the can barrel. As the thickness of each part at the stage of the can, first, the can body with the required flange strength can be manufactured by forming the flange forming area in the maximum thickness part, and the can body upper part by spinning processing It is possible to reliably prevent cracks from occurring during flange processing in which the vertical flange-corresponding portion is formed by extending outwardly to form a flange.

  Further, the reduced diameter neck portion forming region below the inner wall tapered first thickness gradually decreasing portion where the thickness gradually decreases downward from the thick portion, and the subsequent intermediate thickness having a uniform thickness. It is possible to have an ideal shape in which the neck portion gradually increases in thickness from the lower stage to the upper stage when a plurality of stages of necking are performed. Buckling deformation does not occur during necking, and wrinkles can be prevented because of the required thickness. Furthermore, it is possible to obtain a product that can sufficiently withstand the pressing pressure when the beverage is filled in the container. In addition, by forming an upper portion of the neck portion forming region, that is, between the thick portion of the flange portion forming region and the intermediate thick portion in a gently tapered portion, the occurrence of a sudden change in thickness is prevented, It is possible to prevent distortion and the like during necking.

  Further, a neck shoulder portion forming region extending from the lower end portion of the neck portion forming region to the upper end portion of the straight can barrel side wall forming region bulges inwardly in a cross-sectional shape in addition to the thickness corresponding to the intermediate thick portion. By forming the convex thickening portion for dent measures having a thickness less than the maximum thickness portion, the thickness of the neck shoulder portion of the metal can barrel after necking is increased, It is possible to obtain a product excellent in so-called dent resistance, which is free from the occurrence of deformation damage such as dents caused by the close contact or rubbing of products during transportation in the can line or during transportation of the can body.

  Furthermore, the transition region from the neck shoulder forming region to the thin-walled main body forming region of the can barrel side wall is configured as the second tapered thickness-decreasing portion on the inner surface, so that the thickness of the can barrel side wall portion is increased. The bottom shape and neck shape are optimized to improve the pressure strength by reducing the thickness and reducing the weight, and then the transition between the thickened portion of the neck shoulder formation area and the thin main portion of the can body It is possible to prevent an abrupt change in thickness from occurring in the region, and to effectively prevent distortion and the like during necking.

  Therefore, in the manufacturing method of the present invention, the required thickness and workability are ensured for each part of the can body, while the thickness in the vicinity of the open end at the upper end, particularly the thickness in the neck forming area. By further reducing the thickness, further material savings can be achieved compared to the conventional product, which in turn can achieve weight reduction and cost reduction.

  In the inventions described in the above items [2] and [3], the above-mentioned effect is surely and optimally secured in the production of the most commonly used can body for 350 ml and 500 ml aluminum cans. Can do.

  In addition, the invention described in the items [4] and [5] relates to the structure of the can body obtained by the manufacturing method of the invention described in the items [1] to [3].

  First, in the invention described in the item [4], since the flange portion is formed at the maximum thickness portion, the flange portion has a required flange strength and can be stably fitted with the curl portion of the can lid. . Further, it is possible to prevent the occurrence of flange cracking due to flange processing.

  In addition, the reduced-diameter neck portion that follows below is configured as a gradually increasing thickness portion that is relatively thinner than the flange portion and gradually increases in thickness from the bottom to the top. It is possible to sufficiently withstand the presser pressure when filling a beverage.

  Further, the neck shoulder portion extending from the lower end portion of the neck portion to the upper end portion of the straight can barrel side wall portion is configured to be a thickened portion that is equal to or less than the thickness of the flange portion and larger than the thickness of the lower end portion of the neck portion. Therefore, it can be made excellent in dent resistance.

  Furthermore, the thin-walled main part excluding the upper end of the can barrel side wall is configured to have a minimum-thickness, so that the maximum weight reduction can be achieved while satisfying the required pressure resistance and damage resistance. Can be achieved.

  In the invention according to the above item [5], the above effect can be ensured reliably and optimally.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  The present invention, like the can body (1) shown in FIG. 1A, has a flange portion (5) at the upper opening end of the can body side wall portion (3), and a plurality of steps following the flange portion (5). A metal can body (1) made of aluminum or the like having a neck portion (2) is manufactured. As a manufacturing process thereof, a circular punched out from a metal base plate such as an aluminum coil plate is performed as in the prior art. The blank is subjected to drawing and ironing to form a straight bottomed cylindrical can body element (1a), then necked at the upper opening end, and reduced in diameter toward the upper end. A plurality of reduced-diameter neck portions (2) are formed, and further, flange processing is applied to the upper end thereof to form a flange portion (5) for tightening and mounting the can lid.

  The above can manufacturing process is the same as the conventional one, but in the present invention, the bottomed cylindrical shape having a straight side wall portion at the stage where the predetermined drawing and ironing processes are completed before the necking process is performed. The thickness distribution of each part of the can body element can (1a) is restricted to a specific range.

  FIG. 1 shows an example of the shape of the upper end opening of a can body (1) manufactured by the manufacturing method of the present invention. Neck part, (3) is the can body side wall, (4) is the reduced diameter neck part (2) neck shoulder part straddling the lower end part and the upper end part of the can body side wall (3), (5) is the neck part (2) It is a flange part which continues to the upper end of.

  2 and 3 show the upper end of the bottomed cylindrical can body (1a) before the neck portion (2) and the flange portion (5) are formed on the can body (1) of FIG. The thickness distribution state in the vicinity of the opening is shown. In particular, FIG. 3 shows the change in the thickness of each part exaggerated and expressed by the different magnification display method.

  2 and 3, (20) shows a neck portion forming region corresponding to the reduced diameter neck portion (2) in the product can body (1). Similarly, (30) is a can body side wall forming region corresponding to the can body side wall (3), (40) is a neck shoulder portion forming region corresponding to the neck shoulder portion (4), and (50) is a flange portion (5). The corresponding flange part formation area is shown.

  In order to show these correspondences in an easy-to-understand manner, in FIG. 1, the reference numerals of the above-described regions (20), (30), (40), and (50) are added to correspond to the respective parts of the product can body (1). is doing.

In the method of manufacturing the can body (1) according to the present invention, as described above, before the flange portion (5) and the reduced diameter neck portion (2) are formed, that is, before the necking process and the flange process are performed. The thickness distribution of the can body (1a) at the stage is set to the specific range of the following a to d.
a: First, the flange portion forming region (50) is configured as the maximum thick portion (51).

  By forming the flange portion forming region (50) in the maximum thickness portion (51), the flange portion (5) in the can body (1) of the product can be given a required strength, and the can can be formed by spinning. It is possible to reliably prevent the occurrence of a material crack at the time of flange processing for forming the flange portion (5) by projecting the vertical upper end portion of the body can (1a) outward.

The actual thickness of the maximum thickness portion (51) of the flange portion formation region (50) is preferably set in the range of 0.15 to 0.18 mm. When the thickness is less than 0.15 mm, there is a risk of cracking during flange processing. When the thickness is greater than 0.18 mm, the material is wasted and wrinkles are generated in the flange (5). There is a fear. A particularly preferable thickness range is 0.155 to 0.165 mm.
b: a first wall thickness having an inner tapered surface in which the reduced diameter neck portion forming region (20) below the flange portion forming region (50) gradually decreases in thickness downward from the thick portion (51). It consists of a gradually decreasing part (21) and an intermediate thick part (22) of uniform thickness following this.

  The neck portion forming region (20) is composed of the above-mentioned gradually decreasing thickness portion (21) and the intermediate thickness portion (22) having a uniform thickness following the thickness ratio, and the ratio of the lengths in the can axis direction. Is formed in a ratio of about 2: 1 to 1.5, and the neck portion (2) gradually increases in thickness from the lower stage to the upper stage when multiple stages of necking are performed. Further, buckling deformation does not occur at the time of necking, and wrinkles can be prevented from occurring because of the required thickness. Furthermore, it is possible to obtain a product that can sufficiently withstand the pressing pressure when filling a container with a beverage.

  Further, the upper portion of the neck portion forming region (20), that is, the meat whose inner surface forms a gentle taper shape between the thick portion (51) of the flange portion forming region (50) and the intermediate thick portion (22). By forming in the thickness gradually decreasing part (21), generation | occurrence | production of the abrupt thickness change site | part can be prevented and distortion etc. can be prevented in a can body at the time of a necking process.

  The thickness of the intermediate thick part (22) is preferably in the range of 0.12 to 0.16 mm. If it is thinner than 0.12 mm, buckling may occur during necking, and if it is thicker than 0.16 mm, the material is wasted. A particularly preferred thickness is in the range of 0.13 to 0.14 mm.

Further, a first thickness gradually decreasing portion (21) above the neck portion forming region (20), that is, between the thick portion (51) of the flange portion forming region (50) and the intermediate thick portion (22). The inclination angle (θ ₁ ) of the taper surface (21a) of the inner surface of the inner surface of the flange portion forming region (50) is thicker than the thick portion (51) and the neck portion forming region (20) is the intermediate thick portion (22). Although it changes depending on the difference from the thickness of the can, it is preferably in the range of 1 to 25 minutes with respect to the can axis direction. When the inclination angle is smaller than 1 minute, a useless thickened portion is formed in the upper portion of the neck portion, and when it is larger than 25 minutes, wrinkles may occur during necking. A particularly preferred inclination angle is in the range of 8 to 15 minutes.

  c: Next, a neck shoulder portion forming region (40) extending from the lower end portion of the neck portion forming region (20) to the upper end portion of the straight can barrel side wall forming region (30) is changed to the intermediate thick portion (22). In addition to a considerable thickness, it has a trapezoidal bulge portion (41a) that bulges in cross-section inwardly, and the thickness of the top portion of the bulge portion (41a) is less than the maximum thick portion (51). It is comprised in the convex thickening part (41) for a dent countermeasure which has thickness.

  The can after necking is formed by forming the convex thickened portion (41) at a position between the neck portion forming region (20) and the can body side wall forming region (30) so as to straddle both regions. The neck shoulder part (4) of the body (1) is thicker, preventing dents caused by rubbing between products during transportation in the production line or during transportation of the can body. An excellent product can be obtained.

  The protrusion height of the trapezoidal bulge part (41a) is about 0.01 to 0.02 mm with respect to the intermediate thick part (22), and includes the thickness corresponding to the intermediate thick part (22). The maximum thickness is preferably in the range of 0.13 to 0.18 mm. If it is thinner than 0.13 mm, the effect of dent resistance is small, and even if the thickness exceeds 0.18 mm, the effect of dent resistance does not change so much, but the material is wasted. A particularly preferred thickness is in the range of 0.15 to 0.17 mm.

  d: Furthermore, a transition region (30b) that transitions from the neck shoulder portion formation region (40) to the side wall main body (3a) formation region (30a) of the can body side wall (3) has an inner tapered second thickness. The side wall main body forming region (30a) is configured as a predetermined thin portion (32).

  The thickness of the side wall main body forming region (30a) is set to be equal to that of the can body side wall main body (3a) in the can body (1) of the product. By improving the pressure strength by means of, etc., it is possible to reduce the weight by making it as thin as possible. Thus, the thickness of the thin portion (32) of the side wall main portion forming region (30a) is formed to a thickness of about 0.10 to 0.12 mm, which is substantially equal to that of the conventional product. Although it is possible to make the thickness thinner than 0.10 mm, the can body may be damaged, and if it is thicker than 0.12 mm, it goes against weight reduction. A range of 0.105 to 0.11 mm is particularly preferable.

The second thickness gradually decreasing portion (31) in the transition region (30b) prevents a sudden change in thickness by using the inner surface as a gently tapered surface (31a), and prevents distortion and the like during necking. Playing a role. Thus, the inclination angle (θ ₂ ) of the tapered surface (31a) varies depending on the difference between the thickness of the convex thickening portion (41) and the thickness of the thin portion (32) of the side wall main portion (3a). However, the range of 10 minutes to 30 minutes is preferable with respect to the can axis direction. When the inclination angle (θ ₂ ) is smaller than 10 minutes, a useless thickness increase portion is formed above the can barrel side wall (3), and when it is larger than 30 minutes, buckling deformation may occur during necking. is there. A particularly preferable inclination angle (θ ₂ ) is in the range of 15 minutes to 25 minutes.

  In the can body manufacturing method according to the present invention, the can body element can (1a) having the thickness of each part formed in the distribution state as described above is subjected to necking processing and flange processing according to a conventional method. 1 is formed in a can body (3) having a predetermined upper end opening shape as shown in FIG.

  Here, the necking process is a molding in which the diameter of the upper portion of the can body can is gradually reduced, and at present, a four-stage neck can and a smooth neck can are mainly used. In the embodiment, a four-stage neck can has been described as a reduced-diameter neck can, but the present invention can also be applied to a smooth neck can. Moreover, this necking process is generally performed by the die neck method. That is, it is carried out by a system in which the upper end of the can body element can be pushed into the gap between the necking die and the guide block to perform an axially symmetric mouthpiece. The guide block is responsible for preventing wrinkles and stabilizing the inner diameter after squeezing.

  The metal can body (1) such as aluminum obtained by the above-described manufacturing method according to the present invention is based on the thickness distribution of the can body (1a) as described above. The flange portion (5) is configured as the maximum thick portion (15), and the diameter-reduced neck portion (2) following the flange portion (5) is relatively thinner than the flange portion (5), and from the lower stage to the upper stage. The neck shoulder portion (4), which is formed in a gradually increasing thickness portion (12) that gradually increases in thickness toward the upper end portion of the straight can barrel side wall portion (3) from the lower end portion of the neck portion (2), Side wall excluding the upper end portion of the can body side wall (3), which is formed in a thickened portion (14) which is equal to or less than the thickness of the flange portion (5) and larger than the thickness of the lower end portion of the neck portion (2). The main body portion (3a) is configured as a thin-walled portion (13a) having a minimum thickness. In addition, the upper end part of the can body side wall (3) is formed in the thickness decreasing part (13b) corresponding to the thickness decreasing part (31) of an uncoated can (1a).

  Thus, since the flange part (5) is formed in the maximum thickness part, it can have a required flange strength and can perform the coiling | fitting fitting with the curl part of a can lid stably. Further, it is possible to prevent the occurrence of flange cracking due to flange processing.

  The wall thickness of the flange portion (5) is usually preferably set in the range of 0.16 to 0.19 mm.

  Further, since the neck portion (2) is formed so as to gradually increase in thickness from the lower stage to the upper stage, the neck part (2) can sufficiently withstand the pressing pressure when filling the beverage in the container. In particular, the neck portion (2) is preferably formed to have a thick wall thickness in a range of 0.13 to 0.19 mm.

  Moreover, the neck shoulder part (4) including the lower end part of the neck part (2) and the upper end part of the can body side wall part (3) and straddling between both is thicker than the thickness of the lower end of the neck part (2). Therefore, it is possible to provide a can body that is excellent in dent resistance and is less prone to dent deformation.

  The maximum thickness portion of the neck shoulder portion (4) is preferably set in the vicinity of the inflection point at the boundary with the neck portion (2) at the upper end portion of the can barrel side wall portion (3), The thickness of this portion is preferably set in the range of 0.13 to 0.18 mm.

  Further, the thickness of the thin-walled main body portion (3a) of the side wall portion (3) of the can body (1) can be maximized in weight within the range that can satisfy the pressure strength, damage resistance, etc. as described above. It is set to a thickness that can be achieved, and is usually formed to a thickness of 0.10 to 0.12 mm.

<Example>
Samples as various cans of bottomed cylindrical cans for 350 ml cans by using a circular blank punched from a base plate made of A3104 aluminum alloy and forming it into a cup-shaped container by a cupping press. No. A number of 1 to 6 were produced.

  The dimensions such as the thickness of each part in these can bodies were set as shown in Table 1 below.

  Next, the sample No. For each of the can bodies 1-6, necking and flange processing is performed in accordance with conventional methods, and the diameter of the neck is reduced in four steps as it goes upward, and the flange continues to the upper end. Part was molded. In addition, before performing this necking process etc., normal surface treatments, such as a degreasing | defatting process according to a conventional method, a chemical conversion film process, external surface coating, external surface printing, and internal surface coating, were given to the can body.

  Each sample No. obtained by the above necking process and flange process was obtained. It was as shown in following Table 2 when the thickness of each site | part in the aluminum can cylinders 1-6 was measured.

  Therefore, each sample No. For 1-6, the processability of necking and flange processing as described above and the dent resistance of the product can body are compared, and the degree of achievement of weight reduction by reducing the thickness of the neck is compared, and the evaluation results Is shown in Table 3 below.

  The above evaluation method was as follows.

Weight saving:
Sample No. The weight ratio of each sample when the weight of the can body of Comparative 1 corresponding to the current product shown in Fig. 5 (350 ml can with a can body diameter of 66 mm) is 100 was calculated as an average value of 10 cans and compared.

        The weight reduction effect in Table 3 is expressed by the weight ratio of each sample (can body) as a whole, but the volume ratio of the neck portion where the effect of the present invention is manifested is about 12% of the entire can body. Therefore, it can be evaluated that the direct weight reduction effect according to the present invention is a value obtained by multiplying the obtained weight reduction ratio by about 8.3 times.

Buckling deformation of can body:
At the time of necking, a part of the can body was visually inspected for buckling deformation due to the compressive force in the axial direction. In each of the 10 cans 1 to 6, none of the cans were observed, and a part where a part of buckling deformation was observed was marked with a cross.

Flange cracking:
When the flange processing, it was observed with the naked eye whether or not the flange portion was cracked. For each of the 10 cans 1 to 6, no crack was observed in all, and a mark in which some cracks were observed was indicated by an X mark.

Wrinkle occurrence:
The neck formed by necking is visually inspected for wrinkles in part of the circumferential direction. For each of the 10 cans 1 to 6, no wrinkle was observed in any case, and those that had occurred were indicated by a cross.

Processing distortion:
A roundness measuring machine (Mitutoyo Co., Ltd. round) is used to check whether necking and flange processing have caused processing distortions that reduce the roundness of the can body side wall, neck, and flange. Test RA-400), and each sample No. In each of the 10 cans 1 to 6, no generation of processing strain was observed at all, and a case where generation of processing strain was observed was indicated by an x mark.

Dent resistance:
Fill a can body that has been necked and flanged with a predetermined amount of beer as the contents, and fix the beer can with a lid to a jig, and apply a load to the top of the neck shoulder of the beer can. In order to add, a cylindrical jig having the same dimensions as the outer diameter of the beer can was pressed, and a load of 250 N was applied by a compression tester. At that time, the presence or absence of deformation of the neck shoulder portion was examined by naked eye. The case where no dent was observed was indicated by a circle, and the portion where a dent was observed was indicated by a cross.

  According to the present invention, as can be seen from the comparative evaluation of each sample in the above-described embodiment, the weight of the can body can be reduced at the time of necking and flange processing while achieving weight reduction and thus reducing the material cost. It is possible to produce and provide a can body product that does not cause buckling deformation or flange cracking and does not generate wrinkles in the neck portion, has good workability, and has excellent dent resistance.

It is a longitudinal cross-sectional view of the upper end opening part of the can body which concerns on implementation of this invention. It is a longitudinal cross-sectional view of the upper end opening part vicinity area | region of the can body elementary can before the necking process for manufacture of the can body of FIG. It is sectional drawing which showed the thickness distribution state of the upper end opening part vicinity area | region of FIG. 2 in different magnification easily. The conventional can barrel shape, the cross-sectional shape of the area near the upper end opening, and the thickness distribution state of the area near the opening of the can body for manufacturing the can body are shown in correspondence with each other. It is explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Can body 1a ... Can body element 2 ... Reduction diameter neck part 3 ... Can body side wall 3a ... Side wall main part 4 ... Neck shoulder part 5 ... Flange part 6 ... Can bottom part 12 ... Increase in thickness Part 13a ... Thin part 14 ... Increased part 15 ... Maximum thickness part 20 ... Neck part forming region 21 ... First thickness gradually decreasing part 21a ... Tapered surface 22 ... Intermediate thick part 30 ... Can barrel side wall forming region 30a ... Side wall Main body forming region 30b ... Transition region 31 ... Second wall thickness gradually decreasing portion 31a ... Tapered surface 32 ... Thin wall portion 40 ... Neck shoulder portion forming region 41 ... Convex thickening portion 41a ... Swelling portion 50 ... Flange portion forming region 51 ... maximum thickness

Claims (5)

In the method of manufacturing a metal can body having a flange portion and a plurality of reduced diameter neck portions following the flange portion at the upper opening end of the bottomed cylindrical can body,
As the thickness of the bottomed cylindrical can body element before processing to form the flange part and the neck part,
a, configure the flange forming area to the maximum thickness part,
b, a reduced diameter neck portion formation region below the first tapered portion with a tapered inner surface where the thickness gradually decreases downward from the thick portion, and an intermediate thick portion having a uniform thickness following the first tapered portion. And consists of
c. A neck shoulder portion forming region extending from the lower end portion of the neck portion forming region to the upper end portion of the straight can barrel side wall forming region is bulged inwardly in a cross-sectional shape in addition to the thickness corresponding to the intermediate thick portion. While configuring the convex thickening portion for dent measures having a thickness less than the maximum thickness portion,
d, and further, the transition region from the neck shoulder portion forming region to the thin side wall main portion forming region of the can body side wall is configured to be an inner tapered second reduced thickness portion,
A method for manufacturing a metal can body, characterized in that necking processing and flange processing are performed on the can body base can. The thickness of the maximum thickness portion of the flange portion forming region is set in a range of 0.15 to 0.18 mm,
The thickness of the intermediate thick part in the reduced diameter neck part forming region is set in a range of 0.12 to 0.16 mm,
The thickness of the top maximum thickness portion of the convex thickening portion of the neck shoulder portion forming region is set in a range of 0.13 to 0.18 mm,
Furthermore, the thickness of the thin-walled main portion forming region on the side wall of the can body is set in a range of 0.10 to 0.12 mm.
The manufacturing method of the metal can body of Claim 1. An inclination angle with respect to the axis of the inner tapered portion in the first thickness gradually decreasing portion is set in a range of 1 minute to 25 minutes,
The method for manufacturing a metal can body according to claim 1 or 2, wherein an inclination angle of the inner tapered portion of the second thickness gradually decreasing portion with respect to the axis is set in a range of 10 minutes to 30 minutes. In a metal can body having a flange portion and a plurality of reduced diameter neck portions following the flange portion at the upper opening end of the bottomed cylindrical can body,
The upper flange part is composed of the maximum thickness part,
The diameter-reduced neck portion that continues below this is formed into a gradually increasing thickness portion that is relatively thinner than the flange portion and that gradually increases in thickness from the bottom to the top,
The neck shoulder portion spanning from the lower end portion of the neck portion to the upper end portion of the straight can barrel side wall portion is configured to be a thickened portion that is equal to or less than the thickness of the flange portion and greater than the thickness of the lower end portion of the neck portion,
Furthermore, the thin metal main part except the upper end part of the can body side wall is comprised by the thin part of the minimum thickness, The metal can cylinder characterized by the above-mentioned. A thickness of the flange portion is in a range of 0.16 to 0.19 mm;
The wall thickness of the reduced diameter neck portion is changed in the range of 0.13 to 0.19 mm,
The wall thickness of the neck shoulder is in the range of 0.13 to 0.18 mm,
The thickness of the thin-walled main portion of the can barrel side wall is in the range of 0.10 to 0.12 mm.
The metal can body according to claim 4.

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