JP5293345B2 - Method for manufacturing metal can body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a metal can body by which a square pipe type can body having a proper shape even when taking the metal sheet having thin sheet thickness as a base stock can be efficiently manufactured. <P>SOLUTION: When forming a corner part by pinching a cylindrical body portion to be made into the corner part of a square pipe by taking the cylindrical body a obtained from a metal sheet as a material to be formed, using an outer die 4 having a corner-shaped working surface 40 and an inner die 3 having a working surface 30 of a circular cross section on its tip and with the inner die 3 which is situated on the inside of the cylindrical body a, and an outer die 4 which is situated on the outside of the cylindrical body a, the corner part is formed by taking the open angle &theta; of the working surface 40 of the outer die at &lt;90&deg;, so that the open angle &theta; of the outer working surface 40 of the outer die, the radius r of curvature of the working surface 30 of the inner die, the sheet thickness t of the metal sheet and the yield strength &sigma; of the metal sheet satisfy a prescribed conditions. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method of manufacturing a rectangular tube-shaped metal can body, and more particularly to a manufacturing method suitable for obtaining a rectangular tube-shaped can body made of an ultrathin metal plate.

The rectangular tube type container is advantageous in terms of space saving because, for example, when a plurality of containers are packed in a box and packed or displayed at a storefront, the gap between the containers can be reduced. In the case of a beverage container having an inner volume of about 400 mL or less, conventionally, paper has been used as a material for such a rectangular tube type container. Paper containers have the advantage of being light, but have a disadvantage that they are small in strength and easily deform when pressed or dropped.
On the other hand, metal cans are widely used for beverage containers. Metal has a higher strength than paper and is advantageous for deformation of the container. However, in the past, metal was rarely used as a material for a rectangular tube type beverage container. This is probably because the metal can is heavier than the paper container. To lighten the metal can, it is effective to reduce the thickness of the material metal plate.

  Patent Document 1 discloses a method of forming a rectangular tube-shaped metal can using a material having a thin plate thickness. In this method, a rectangular material sheared to a predetermined dimension is formed into a cylindrical body by seam welding, and a square tube is formed by squaring (molding corners). The cornering is performed by using a plurality of sets of inner molds and outer molds corresponding to the number of corners to be molded, and the corners are further grooved. According to this method, a steel plate having a thickness of up to 0.1 mm can be formed into a rectangular tube-shaped metal can.

Japanese Patent Publication No.61-34891

  However, as a result of experiments conducted on the method of Patent Document 1 by using the ultrathin steel plate having a thickness of 0.1 mm, the inventors found that the following problems occur. First, when squaring and grooving were performed, breakage occurred at the grooving portion. Since this rupture occurred in the grooved portion, when it was molded without grooving, the corner portion did not become a predetermined angle (generally 90 °), and as a result, the side wall surface curved toward the outside of the cylinder. As a result, the result was that the square tube was not properly shaped. That is, in forming a square tube having four corners and a side wall surface, as shown in FIG. 3 (a plan view of the can body seen from the height direction), the side wall surface 1 is substantially flat and the corner portion 2 is formed. In this case, an attempt was made to obtain a shape having an angle α (corner angle) of approximately 90 °, but actually, as shown in FIG. 4 (a plan view of the can body as viewed from the height direction), the side wall surface 1 is outside. And the angle α of the corner portion 2 becomes considerably larger than 90 °, and it has been found that an appropriate shape as a square tube cannot be obtained. In such a shape, the advantage as a rectangular tube type container that the space | gap between containers can be made small is not acquired. Here, the angle α of the corner 2 described above is defined as follows. That is, as shown in FIG. 14, assuming a circle 20 (virtual circle) having a radius of curvature b of the corner 2 and in contact with the corner 2, circles at points 21 and 22 where the circle 20 and the corner 2 are separated from each other. When 20 tangent lines 23 and 24 are determined, an angle formed by the tangent line 23 and the tangent line 24 is defined as an angle α of an angle 2.

As described above, a manufacturing technique for a rectangular tube can body using a thin metal plate as a raw material has not yet been established.
Accordingly, an object of the present invention is to provide a method for manufacturing a metal can body that can efficiently manufacture a square-shaped can body having an appropriate shape even when a thin metal plate is used as a raw material. .

［2］上記［1］の製造方法で得られた金属缶胴の少なくとも一方の端部に蓋を固定し、金属缶とすることを特徴とする金属缶の製造方法。 The gist of the present invention for solving the above problems is as follows.
[1] An inner mold located on the inner side of a cylindrical body using a cylindrical body of a metal plate as a material to be molded, an outer mold having a corner-shaped machining surface, and an inner mold having a machining surface having an arc-shaped cross section at the tip, In the manufacturing method of the rectangular tube can body that molds the corner portion by sandwiching the cylindrical portion to be the corner portion of the rectangular tube with the outer mold located outside the cylindrical body,
The opening angle θ of the outer die machining surface is less than 90 °, the opening angle θ (°) of the outer die machining surface, the radius of curvature r (mm) of the inner die machining surface, the thickness t (mm) of the metal plate, and the metal A method for producing a metal can body, characterized in that the corner portion is formed under the condition that the yield strength σ (N / mm ² ) of the plate satisfies the following formula (1).

[2] A method for producing a metal can, characterized in that a lid is fixed to at least one end of the metal can body obtained by the production method of [1] to obtain a metal can.

  According to the present invention, using a thin metal plate as a raw material, an appropriately shaped rectangular tube can body having a side wall surface that is substantially flat and a corner angle (corner angle) of approximately 90 ° is efficiently produced. Can be manufactured.

It shows an example of the implementation status of the production method of the present invention, (A) is before molding, (B) is during molding, (C) is a plan view showing each state after molding Plan view showing the structure of the outer mold and the inner mold used in the present invention Explanatory drawing which shows the proper can body shape (planar shape of the can body seen from the height direction) obtained by the formation process of a square tube type can body Explanatory drawing which shows the improper can body shape (planar shape of the can body seen from the height direction) obtained by the formation process of a rectangular tube type can body In the method of Patent Document 1, a material (cylindrical body) before molding and a molding means (inner mold, outer mold) when performing an experiment for squaring without grooving a corner are shown. Plan view from the height direction FIG. 5 is a plan view showing one set of inner mold and outer mold used in the experiment of FIG. In the method of Patent Document 1, the angle α of the corner of the can body obtained when an experiment for squaring without grooving the corner is shown in relation to the radius of curvature r of the inner die machining surface. Graph 7 is an explanatory diagram for explaining a phenomenon in which the angle α of the can barrel corner portion is 95 ° or more in the experiment of FIG. FIG. 7 is a graph in which the results of FIG. 7 are arranged by the relationship between σ · r / (1000 · t) and the angle α of the can barrel corner. The angle α of the can body corner portion obtained when the can body corner portion is formed by setting the open angle θ of the outer die processing surface to 50 to 90 ° is shown in relation to the open angle θ of the outer mold processing surface. Graph Based on the results of FIG. 10, a graph in which the condition that the angle α of the can barrel corner is 90 ° is arranged by the relationship between the open angle θ of the outer die machining surface and σ · r / (1000 · t). Based on the results of FIG. 10, a graph in which the conditions at which the angle α of the can body corner portion is 85 ° to 93 ° are arranged in relation to the open angle θ of the outer die machining surface and σ · r / (1000 · t). Sectional drawing of forming means (inner mold, outer mold) for grooving corners in the method of Patent Document 1 Explanatory diagram for defining the angle α of the corner

In the method of manufacturing a rectangular tube can body according to the present invention, a cylindrical body of a metal plate is used as a material to be molded, and the corner portion of the rectangular tube is formed by an inner mold positioned inside the cylindrical body and an outer mold positioned outside the cylindrical body. The cylindrical portion to be formed is clamped to form the corner portion.
FIG. 1 shows an example of the implementation status of the production method of the present invention, where (A) is before molding, (B) is during molding, and (C) is a plan view showing each state after molding. In the figure, a is a cylindrical body which is a material to be molded, and is obtained by joining opposite end edges of a rectangular metal plate deformed into a cylindrical shape by seam welding or the like. A is a molded square tube. 3 is an inner mold positioned inside the cylindrical body a, 4 is an outer mold positioned outside the cylindrical body a, and four sets of molding molds each having the inner mold 3 and the outer mold 4 are provided. Forming means are configured.

FIG. 2 is a plan view showing a pair of inner mold 3 and outer mold 4.
The outer mold 4 has a corner-shaped processed surface 40 (processed surface) having a predetermined opening angle θ, and the processed surface 40 restrains the outer surface side of the can barrel corner at the time of molding. The inner die 3 has a processing surface 30 having a circular arc shape (arc shape in a horizontal cross section) having a predetermined radius of curvature r at the tip, and at the time of molding, the processing surface 30 extends to the inner surface side of the can barrel corner. to bound. More specifically, the result is that the material is bent along the machining surface 30 of the inner mold 3 while being pressed between the two points of the arc-shaped machining surface 30 of the inner mold 3 and the machining surface 40 of the outer mold 4. Each corner of the can body is molded.
In addition, the preferable form of the inner mold | type 3 and the outer mold | type 4 is demonstrated in detail later.

In the manufacturing method of the present invention, as shown in FIG. 1 (a), four sets of inner mold 3 and outer mold 4 are arranged with respect to the cylindrical body a so as to be equally spaced in the circumferential direction of the cylindrical body a. In this state, as shown in FIG. 1B, the four portions of the inner die 3 and the outer die 4 are used to sandwich the cylindrical portion that should become the corner of the square tube, thereby forming the corner. As a result, a square tube A having a corner portion 2 and a side wall surface 1 as shown in FIG.
In the present invention, in such a molding step, the open angle θ of the outer mold processed surface 40 is set to less than 90 °, the open angle θ (°) of the outer mold processed surface 40, and the radius of curvature r ( mm), the thickness t (mm) of the metal plate, and the yield strength σ (N / mm ² ) of the metal plate satisfy the following formula (1). Hereinafter, the details of the production method of the present invention and the results of the study that led to the present invention will be described.

When forming the ultra-thin steel plate by the method of Patent Document 1, the present inventors break as a result of grooving as described above, and the side wall surface is curved toward the outside of the can body and has an appropriate shape. The reason why it was not a square tube was examined in detail.
First, it is considered that the rupture caused by grooving is due to the following reasons. Grooving in the method of Patent Document 1 is performed by forming a material 14 (metal plate) with a punch 12 provided in the outer mold 11 and a recess 13 provided in the inner mold 10 as shown in FIG. . At this time, the material 14 constrained by the inner mold 10 is pushed into the recess 13 by the punch 12 and stretched. There is no problem as long as the material 14 has sufficient elongation that can withstand such molding, but if the elongation is inferior, it is considered that the material cannot withstand molding and breaks. The elongation of the material is a material property determined by its chemical composition, manufacturing method, metal structure, etc., but on the other hand, it is greatly influenced by the plate thickness, and the elongation decreases as the plate thickness decreases. Conventionally, an ultra-thin steel sheet having a thickness of about 0.1 mm that has not been used in the can manufacturing field has a low elongation even if the material characteristics are equivalent compared to a steel sheet having a larger thickness. Therefore, it is considered that the fracture occurred at the grooved portion.

Breaking the material is a phenomenon that should not occur because it leads to leakage of the contents in the beverage container. Therefore, it is desirable not to perform grooving which is a cause of breakage. Therefore, an experiment was conducted in which the inner mold and the outer mold were squared without grooving.
In this experiment, specimens A to D (tinned steel sheets) having a thickness t and a yield strength σ shown in Table 1 were used. The test material was formed into a cylindrical body a having an outer diameter of 52.4 mm and a height of 136.7 mm by seam welding, and an inner mold 5 (processing with an arc-shaped cross section at the tip) arranged as shown in FIG. A corner portion was formed by an outer mold 6 (an outer mold having a surface 50) and an outer mold 6 (an outer mold having a corner-shaped processed surface 60) to form a rectangular tube-shaped can body. The opening angle θ of the processed surface 60 of the outer mold 6 shown in FIG. 6 is not described in Patent Document 1, but is 90 degrees when measured in the drawing of the same document, and thus is the same here. Moreover, as for the curvature radius r of the processing surface 50 of the inner mold 5 shown in FIG. 6, 22 mm is exemplified for the 18 L can in Patent Document 1, but the present invention mainly uses a small can of about 400 mL or less. Since it is assumed, the thickness is set to 2 to 8 mm in this experiment in consideration of the difference in size. The four sets of the inner mold 5 and the outer mold 6 were arranged so that each set was equally spaced in the circumferential direction of the cylindrical body a. About the can body after shaping | molding, the angle (alpha) (corner angle) of the corner | angular part 2 was measured.

  FIG. 7 shows the result of arranging the angle α of the can barrel corner 2 with the radius of curvature r of the inner mold processed surface 50. According to the figure, the angle α of the can body corner portion 2 is 95 ° or more, and the side wall surface 1 is curved toward the outside of the tube under any condition, and the square tube of an appropriate shape does not work. It was. The reason is considered as follows. An outline of molding in this experiment is shown in FIG. As shown in FIG. 8 (a), when the cylindrical body (material to be molded) is sandwiched between the inner mold 5 and the outer mold 6, the side wall surface 1 of the rectangular tube A is flat while the mold is in contact. The angle of the corner portion 2 is 90 ° along the open angle θ of the outer mold processing surface 60. However, as shown in FIG. 8 (b), in the can body A released from the mold after molding, the angle part 2 is opened by the spring back, so that the angle α becomes larger than 95 °. Is curved toward the outside of the cylinder. In the method of Patent Document 1, since the groove is formed, that is, the two inner mold tip portions (processed surfaces) having a small radius of curvature are bent at two locations, the spring back of the corner portion 2 is suppressed by the effect. It is considered to be done.

  Therefore, in order to suppress the curvature of the side wall surface, the angle α of the can barrel corner after being released from the mold should be close to 90 °. Therefore, when the experimental result is examined again in order to find a method for controlling the angle α, the larger the yield strength σ of the material and the larger the radius of curvature r of the inner working surface, the more the thickness t of the material. Is smaller, the angle α is larger. In other words, the angle α of the can barrel corner is proportional to the yield strength σ of the material and the radius of curvature r of the inner surface, and inversely proportional to the thickness t of the material. Accordingly, FIG. 9 shows the relationship between σ · r / (1000 · t) and the angle α of the can body corner portion, with respect to the experimental results described above. Here, the thickness t is multiplied by 1000 in order to simplify the calculation by setting the absolute value of σ · r / (1000 · t) to the same value as the angle α. . According to FIG. 9, it can be understood that the angle α of the can barrel corner can be unified by using σ · r / (1000 · t) as an index. That is, in order to control the angle α of the can body corner portion, it is understood that the relationship between the yield strength σ of the material, the plate thickness t, and the curvature radius r of the inner die machining surface may be adjusted.

In order to reduce the angle α of the can barrel corner, it is better that the plate thickness t of the material is thicker, the yield strength σ is lower, and the radius of curvature r of the inner die working surface is smaller. However, in order to obtain a lightweight can body aimed by the present invention, the thickness t of the material is preferably thin, and is preferably about 0.10 to 0.15 mm. Further, from the viewpoint of securing the strength of the can body, in order to compensate for the thin plate thickness, the material should have a high yield strength σ, preferably about 300 to 750 N / mm ² . Further, the radius of curvature r of the inner die working surface is preferably large so as not to damage the material when the inner die contacts, and is preferably approximately 2 mm or more. Thus, the desirable conditions for the material thickness t, yield strength σ, and radius of curvature r of the inner working surface are all the conditions necessary to reduce the angle α of the can barrel corner and approach 90 °. Are in a conflicting relationship. Moreover, the angle α of the can barrel corner obtained in such a range of the desired thickness t, yield strength σ, and radius of curvature r of the inner working surface is at least 95 ° in the experimental results of FIG.

Therefore, the present inventors pay attention to the open angle θ of the outer mold processed surface, and consider that the angle α of the can barrel corner can be set to 90 ° by setting the open angle θ to a smaller angle. In order to confirm this, the following experiment was conducted.
Using test materials (i) to (iv) (tin-plated steel plates) having a thickness t and a yield strength σ shown in Table 2, the test materials were seam welded to have an outer diameter of 52.4 mm and a height of 136. A cylindrical body of 7 mm was formed, and the corner of the can body was molded using the inner mold and the outer mold in the same manner as in FIG. In this experiment, the can body corner portion was formed by setting the radius of curvature r of the inner die machining surface to 2 mm and 4 mm and the open angle θ of the outer die machining surface to 50 to 90 °. FIG. 10 shows the relationship between the open angle θ of the outer mold processed surface and the angle α of the can barrel corner obtained in this experiment. As shown in the figure, the angle α of the can barrel corner can be set to a value close to 90 ° by appropriately setting the opening angle θ of the outer mold processed surface.

  The appropriate opening angle θ of the outer die machining surface varies depending on the conditions (i) to (iv) in Table 2, that is, depending on the combination of the material thickness t, the yield strength σ, and the curvature radius r of the inner die machining surface. Therefore, based on the result of FIG. 10, the conditions in which the angle α of the can body corner portion is 90 ° are arranged in relation to the open angle θ of the outer mold processed surface and σ · r / (1000 · t). 11. In other words, the angle of the can barrel corner is formed by molding the can barrel corner under the condition satisfying the relationship between the opening angle θ of the outer die machining surface shown in FIG. 11 and σ · r / (1000 · t). A can body having α of 90 ° and a flat side wall surface is obtained.

In order to use the can body manufactured according to the present invention as a rectangular tube-shaped container, after providing flange portions at both ends (both openings) of the can body, similarly, a lid provided with the flange portions is mounted and both flanges are mounted. The lid is attached and fixed by tightening the part. Here, the advantage of the rectangular tube container that the gap between the containers can be reduced is that the side wall surface of the can barrel is strictly flat and the angle α of the can barrel corner portion is not 90 °, that is, the can barrel If the side wall surface is substantially planar and the angle α of the can body corner is close to 90 °, the problem can be substantially obtained.
For example, when the angle α <90 ° of the can body corner portion, the side wall surface of the can body is curved inward, and if the degree is large, it is difficult to attach the lid. However, if the degree of curvature of the side wall surface is small, there will be no substantial hindrance to the mounting of the lid, and the above advantages as a rectangular tube container will not be lost.

  On the other hand, when the angle α> 90 ° of the can body corner portion, the side wall surface of the can body is curved outward, and if the degree is large, it is difficult to attach the lid. In addition, even if the side wall surface of the can body is curved outward because the angle α> 90 °, the shape in the vicinity of both ends of the can body is constrained and the curvature is corrected by attaching the lid, and the influence of the curvature However, since the correcting action does not work at the part away from both ends of the can body, the can body is curved outward. However, if the degree of bending of the side wall surface to the outside of the can body is small, there is no substantial hindrance to the mounting of the lid, and the degree of bending after the mounting of the lid is small, and the above advantages as a rectangular tube container are lost. There is nothing.

  According to the results examined by the present inventors, even when the angle α <90 ° of the can barrel corner, if the angle α ≧ 85 °, the degree of curvature of the side wall surface is small, and the lid is substantially attached. It was found that there was no problem. On the other hand, even if the angle α> 90 ° of the can body corner, if the angle α ≦ 93 °, the degree of curvature of the side wall surface is small, so that there is no substantial hindrance to the mounting of the lid, It has been found that the amount of protrusion of the curved portion after mounting the lid is about 1 mm or less and does not protrude outward beyond the width of the winding portion, so that there is substantially no problem. That is, it has been found that the can is formed so that the angle α of the corner portion of the can is in the range of 85 ° to 93 °.

Therefore, based on the results of FIG. 10, the conditions under which the angle α of the can barrel angle portion is 85 ° to 93 ° are arranged by the relationship between the open angle θ of the outer mold processed surface and σ · r / (1000 · t). The thing is FIG. That is, by forming the can barrel corner portion under the condition of the following formula (1) that satisfies the relationship between the open angle θ of the outer mold processed surface shown in FIG. 12 and σ · r / (1000 · t). A can body having an angle [alpha] of the can body corner portion of 85 [deg.] To 93 [deg.] And a substantially flat side wall surface is obtained.
Therefore, in the present invention, the open angle θ of the outer die machining surface is less than 90 °, the open angle θ (°) of the outer die machining surface, the radius of curvature r (mm) of the inner die machining surface, and the thickness of the metal plate. The corner portion is formed under the condition that t (mm) and the yield strength σ (N / mm ² ) of the metal plate satisfy the following expression (1).

  As a material of the can body manufactured by the present invention, a steel plate subjected to various surface treatments for ensuring corrosion resistance is desirable. As such a surface-treated steel plate, one or more of tin, zinc, nickel, chromium, etc. are plated on the surface of the steel plate, and further, the chromate treatment or phosphate treatment is applied to the upper layer of the plated layer. Those subjected to various chemical conversion treatments are suitable. Among these, tin-plated steel plates (baffle) and electrolytic chromate-treated steel plates (tin-free steel) conventionally used for beverage containers are suitable. Moreover, the laminated steel plate which coat | covered the organic resin film on various surface treatment steel plates is especially suitable from viewpoints, such as corrosion resistance and environmental compatibility.

Although there is no special restriction | limiting in the plate | board thickness of a metal plate, 0.095-0.155mm is suitable from a viewpoint of weight reduction of a container. The yield strength σ of the metal plate is particularly preferably about 360 to 650 N / mm ² .
In order to obtain a cylindrical body a which is a material to be molded, the opposite end edges of a rectangular metal plate deformed into a cylindrical shape are usually joined to form a cylindrical body. The method for joining both edge portions of the metal plate is not particularly limited as long as sufficient joining strength is obtained, but a welding method, an adhesion method, a solder method, or the like can be used. Among these, a welding method with particularly high joint strength is suitable. As the welding method, current welding such as seam welding, laser welding, or the like can be applied.

Next, preferred forms of the inner mold and the outer mold, which are molding means used in the present invention, will be described with reference to FIG.
The basic configuration of the inner die 3 and the outer die 4 is as described above, but the material between the two points of the arc-shaped machining surface 30 of the inner die 3 and the corner-like machining surface 40 of the outer die 4 is a material. Since each corner portion of the can body is formed while the pressure is held, the processed surface 30 of the inner mold 3 needs to be in contact with the outer mold 4 with the processed surface 40 of the outer mold 4 being in contact. Therefore, if the depth of the processed surface 40 of the outer mold 4 is L (mm), the relationship between the radius of curvature r (mm) of the inner processed surface 30 and the open angle θ (°) of the outer processed surface 40 is L Must satisfy the following conditions geometrically.
L> r / tan (θ / 2)

However, if L is too large, adjacent outer molds 4 interfere with each other, so there is a substantial upper limit. The preferred range of L varies depending on the size of the can, the radius of curvature r of the inner mold processing surface 30, and the like. For example, in order to manufacture a metal can having an internal capacity of about 300 mL, the radius of curvature r of the inner mold processing surface 30 is set. When it is about 2-6 mm, it is desirable that it is about 4-20 mm.
The radius of curvature r of the inner working surface is not particularly limited except for the condition of the above formula (1), but is generally about 1 to 20 mm, and a particularly preferable range is 2 to 16 mm.
Since the inner mold 3 and the outer mold 4 need to accurately mold the can barrel corner, it is necessary that the mold itself does not deform when the material is molded. Therefore, it is desirable to be a rigid body, and it is desirable to use a material such as a metal used in normal metal processing.

There is no particular limitation on the size of the rectangular tube can body manufactured according to the present invention, the size of the rectangular tube container using the can body, or the internal capacity, but a particularly preferable rectangular tube can body and rectangular tube container The size between the opposite side wall surfaces is about 4 cm to 5 cm, the can height is about 5 cm to 15 cm, and the internal volume is about 80 to 400 mL. In addition, a rectangular tube can body and a rectangular tube container having a square cross section are manufactured according to the present invention.
The can body manufactured according to the present invention has a lid attached to at least one end to form a rectangular tube-shaped metal can. The attachment of the lid is usually performed by providing flange portions on the periphery of the end of the can body and the periphery of the cover, and winding both flange portions in a state where the cover is attached to the end of the can body.

A tin-plated steel sheet having a thickness t and a yield strength σ shown in Table 3 was used as a test material. After this test material was formed into a cylindrical body having an outer diameter of 52.4 mm and a height of 136.7 mm by a seam welding method, the curvature radius r of the inner die machining surface and the open angle θ of the outer die machining surface shown in Table 3 were set. Square forming was performed with four pairs of inner mold and outer mold. About the can body thus obtained, the angle α of the corner portion was measured. The results are also shown in Table 3.
As shown in Table 3, it can be seen that in the example of the present invention, the angle α of the can barrel corner is in the range of 85 ° to 93 °.

Here, f1 and f2 in Table 3 indicate the right side and the left side of the equation (1) as follows.

DESCRIPTION OF SYMBOLS 1 Side wall surface 2 Corner | angular part 3,5 Inner type | mold 4,6 Outer type | mold 30,50 Inner type | mold processed surface 40,60 Outer type | mold processed surface a Cylinder A Square tube

Claims (2)

A metal plate cylinder is used as a material to be molded, and an outer mold having a corner-shaped machining surface and an inner mold having an arc-shaped machining surface at the tip are used. In the manufacturing method of the rectangular tube type can body for forming the corner portion by sandwiching the cylindrical body portion to be the corner portion of the rectangular tube by the outer mold located at
The opening angle θ of the outer die machining surface is less than 90 °, the opening angle θ (°) of the outer die machining surface, the radius of curvature r (mm) of the inner die machining surface, the thickness t (mm) of the metal plate, and the metal A method for producing a metal can body, characterized in that the corner portion is formed under the condition that the yield strength σ (N / mm ² ) of the plate satisfies the following formula (1).

  A metal can manufacturing method, wherein a lid is fixed to at least one end of a metal can body obtained by the manufacturing method according to claim 1 to form a metal can.

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