JP3718865B2 - Manufacturing method of lightweight can with excellent bottom pressure strength - Google Patents

Description

【００３９】
【表２】

【００４０】
表２に示した結果から、本発明法に従って製缶を行えば、他の特性を犠牲にすることなしに、十分に高いボトム部耐圧強度が得られたことがわかる。また、得られた缶を観察したところ、本発明に従って得られた缶は、その表面性状および耐食性は良好であり、さらに途中工程の冷間圧延性も良好であることを確認した。
【００４１】
・実施例２
表３に示す成分組成の鋼を転炉にて溶製した後、表４に示す製造条件にて薄鋼板および錫めっき鋼板を製造し、その後実施例１と同様の手順で諸特性を評価した結果について表５に示す。なお、表４に示す条件で製造された鋼板の平均ｒ値は1.85およびΔｒ値は絶対値で0.05であった。
【００４２】
【表３】

【００４３】
【表４】

【００４４】
【表５】

【００４５】
表５に示した結果から、本発明に従って製缶することによって、他の特性を犠牲にすることなしに、十分に高いボトム部耐圧強度が得られたことがわかる。また、再絞り加工およびしごき加工の工程を詳細に観察したところ、本発明に従う工程では、成形時のパンチからの抜け性、いわゆるストリッピング性も改善されていた。この点を詳細に実験した結果、抜け性不良の発生率は従来法対比で１／３に減少したことも判明した。
【００４６】
【発明の効果】
本発明法によれば、極低炭素鋼板の良好な成形性を生かしたＤＩ缶成形が可能となり、かつ、十分に高いボトム耐圧強度が達成できる。しかも本発明法によれば、ノンイヤリング性、ネックイン成形性およびストリッピング性などの他の製缶特性も優れている。
このため、自動車用に製造された特定の極低炭素鋼を素材とし、製造条件を最適化することにより、ＤＩ缶を製造できるので、製鋼工程での鋼種数を減少でき、製造原価が低減できる。[0001]
[Industrial application fields]
The present invention relates to a method for producing a lightweight can, particularly a DI (Drawn and Wall Ironed) can used mainly in beverage cans.
[0002]
[Prior art]
In general, a DI can is manufactured from a predetermined material through a process roughly divided into two processes.
For example, a 350 ml can is a so-called first cup with a diameter of about 30-35mm and a bottom diameter of about 90mm. In the first step for producing a shallow intermediate cup, and the second step in which the obtained first cup is continuously subjected to redrawing and ironing in about three stages. . In addition, the redrawing process and the ironing process, which are the second process, are performed with extremely high efficiency in one process, and the apparatus used here is a highly complete apparatus called a body maker.
[0003]
The above-mentioned can-making method is mainly made of aluminum material having an alloy number of about 3004 in JIS H4000, T3-BA (box annealing material with tempering degree T3) and T3-CA (continuous annealing material with tempering degree T3). It is not applied when the hard low carbon aluminum killed steel is used as a material. This is because low carbon aluminum killed steel has poor workability and cannot withstand the above-mentioned can-making method.
[0004]
However, due to recent advances in steel technology, it has become possible to reduce the carbon of steel, and this has made it possible to compensate for the deterioration of workability, which is a problem of low-carbon aluminum killed steel. Application has been studied (see Japanese Patent Application Laid-Open Nos. 4-280926 and 58-197224).
[0005]
[Problems to be solved by the invention]
However, although the workability of the steel sheet has been improved due to the extremely low carbon, it remains a problem that a reduction in strength, in particular a reduction in the strength of the can body represented by the bottom pressure strength in the can obtained by processing, inevitably occurs. Furthermore, for application to DI cans, the characteristics of generating less ears when drawing is performed, that is, the improvement of non-earring properties, and the process of reducing the can diameter after canning, that is, neck-in Each improvement in formability was essential.
[0006]
Accordingly, many improvements have been indispensable in order to apply this seed steel plate, which was originally developed mainly as a steel plate for automobiles, to a steel plate for cans as it is.
Therefore, the present invention enables the production of DI cans without incurring the above disadvantages even when applied to steel plates (hereinafter also including surface treatment materials) made of ultra-low carbon steel. It aims at proposing about the technique to do.
[0007]
[Means for Solving the Problems]
The inventors have made various studies on steel sheets having excellent workability, particularly steel sheets having a high average r value, including characteristics such as non-earring properties and neck-in formability required for DI cans. However, a steel sheet effective for improving the neck-in formability has been developed, but the strength of the can body cannot withstand practical use because this steel sheet has low strength. Furthermore, in order to solve this problem, we focused on the DI can molding process, especially the first cup molding process that has not been studied so far, and examined the conditions in this process in detail. A technique for obtaining strength was found and the present invention was completed.
[0008]
That is, the gist configuration of the present invention is as follows.
(1) C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S : 0.010wt% or less and N: 0.0050wt% or less, the balance has a chemical composition consisting of Fe and inevitable impurities, the average r value is adjusted to 1.50 or more, and the Δr value is adjusted to an absolute value of 0.30 or less Using a steel plate with a thickness of 0.30 mm or less as a raw material, after punching the material, drawing is performed under the conditions of drawing ratio: 1.80 or more and bottom thickness reduction ratio: 10% or more, then redrawing And a method for producing a lightweight can excellent in bottom pressure strength, characterized by performing ironing.
[0009]
(2) C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S : Containing 0.010 wt% or less and N: 0.0050 wt% or less, further containing at least one of Ni: 0.05 to 0.50 wt%, Cr 0.05 to 0.50 wt% and Cu: 0.05 to 0.50 wt%, the balance Has a chemical composition consisting of Fe and unavoidable impurities, with an average r value of 1.50 or more and a Δr value adjusted to an absolute value of 0.30 or less, and a steel plate having a thickness of 0.30 mm or less, and punching the material. After processing, drawing is performed under the conditions of drawing ratio: 1.80 or more, bottom thickness reduction ratio: 10% or more, then redrawing and ironing, and light weight with excellent bottom pressure strength A method for manufacturing cans.
[0010]
(3) C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S : Containing 0.010 wt% or less and N: 0.0050 wt% or less, further containing Ti: 0.005 to 0.0100 wt%, the balance having a chemical composition consisting of Fe and inevitable impurities, with an average r value of 1.50 or more, In addition, a steel sheet with a thickness of 0.30 mm or less, whose Δr value is adjusted to an absolute value of 0.30 or less, is used as a raw material. A method for producing a lightweight can excellent in bottom pressure strength, characterized by being applied under the above conditions and then performing redrawing and ironing.
[0011]
In the present invention, in order to improve the workability and aging resistance, the amount of C is reduced to 0.0005 to 0.0050 wt%, other impurity components are reduced, and Nb is contained in an appropriate range to achieve the final cooling. A steel sheet is produced by appropriately controlling the texture of the annealed sheet. Next, after punching the obtained steel sheet, the first process of DI can production is the first step of forming the first cup. Utilizing the significant expansion of the forming range compared to the conventional steel sheet due to the improved workability of the steel sheet used In addition, the drawing ratio is 1.80 or more and the bottom portion thickness reduction rate, that is, the bottom thickness reduction rate with respect to the plate thickness before processing is 10% or more on the average of the entire bottom portion, Under the molding conditions, an elongation strain is positively imparted to a portion to which almost no strain is imparted and work hardening is performed, and in particular, the pressure strength of the bottom portion is increased.
[0012]
[Action]
Below, each limitation reason in this invention is described in an order from a component composition.
C: 0.0005-0.0050wt%
The amount of C is preferably reduced from the viewpoint of improvement in elongation and r value. However, if it is less than 0.0005 wt%, the surface after processing becomes rough due to marked coarsening of the particle size, so-called orange peel phenomenon becomes obvious and the appearance is poor. There is a risk of causing trouble. On the other hand, if it exceeds 0.0050 wt%, the r value tends to decrease and the deterioration of aging resistance becomes remarkable. In order to improve the workability, it is preferably limited to 0.0030 wt% or less.
[0013]
Si: 0.20wt% or less
When Si is contained in an amount exceeding 0.20 wt%, the surface treatment property deteriorates remarkably, so it is limited to 0.20 wt% or less, more preferably 0.02 wt% or less. The lower limit is not particularly limited because it is related to the Si reduction cost in the steelmaking process.
[0014]
Mn: 0.05-1.00wt%
In order to prevent red hot brittleness of steel, it is necessary to contain Mn according to the amount of S inevitably mixed in, but by containing at least 0.05 wt%, red hot brittleness can be prevented. Further, it is possible to increase the strength by containing Mn. The details of the mechanism for increasing the strength are not clear, but are thought to be related to the lowering of the transformation point. That is, although the solid solution strengthening ability of Mn itself is not so great, the refinement of the structure is promoted, the rough skin resistance necessary for the steel plate for cans is improved, and at the same time, strengthening by fine graining can be expected. Furthermore, the inclusion of Mn reduces the recrystallization temperature in the annealing process after cold rolling, and can relax the regulation of operating conditions. Although the details of this mechanism are not clear, it is thought to be due to uniform coarsening of precipitates.
On the other hand, if the Mn content exceeds 1.00 wt%, the deterioration of workability, which is represented by a decrease in the average r value, becomes remarkable. Therefore, it is 1.00 wt% or less, and 0.60 wt% or less to obtain a higher r value. More preferably, it is preferably limited to 0.30 wt% or less.
[0015]
Al: 0.005 to 0.100 wt%
Al is contained as a deoxidizing material for steel as in the case of conventional steel, and the amount of non-metallic inclusions in the steel is reduced to prevent cracks in the flange due to these inclusions. It is an essential component from the viewpoint of fixing and stabilizing and improving the average r value, and 0.005 wt% or more is necessary. On the other hand, if the amount exceeds 0.100 wt%, alumina clusters and the like are likely to be generated on the surface of the steel sheet and cause surface defects. In particular, in order to reduce the rate of occurrence of steel sheet edge cracking during hot rolling, it is preferable that the range be 0.020 to 0.060 wt%.
[0016]
Nb: 0.003 to 0.020 wt%
Nb is required to improve the in-plane anisotropy and average r value of the steel sheet, and is also effective for preventing grain roughening and roughening during forming, so 0.003 wt% or more is necessary. . On the other hand, if it exceeds 0.020 wt%, the recrystallization temperature will rise and the annealing process after cold rolling will not work effectively, and in the manufacturing process of the steel sheet for ultrathin cans targeted in the present invention, Δr will deteriorate. Since it becomes especially remarkable, it is 0.020 wt% or less. In order to ease the regulation of manufacturing conditions including hot rolling conditions and reduce component costs, 0.015 wt% or less is preferable.
[0017]
P: 0.100 wt% or less,
P is a component that is used as a supplement because it has a high solid-solution strengthening ability like Si, but a large amount causes deterioration of corrosion resistance and embrittlement of the material, and also raises the recrystallization temperature. , 0.100 wt% or less. In addition, Preferably it is 0.005 to 0.040 wt%.
[0018]
S: 0.010 wt% or less By reducing the amount of S, inclusions in the steel are reduced and workability is improved, so the content is suppressed to 0.010 wt% or less. In particular, when the gauge down (reduction in the thickness of the steel plate) proceeds, the effect of the reduction in the amount of S is remarkable. More desirably, if it is 0.005 wt% or less, it is more effective in workability, particularly in stretch flange characteristics and corrosion resistance of the sheared portion.
[0019]
N: 0.0050 wt% or less N, if remaining in large amounts, the neck-in formability deteriorates due to the aging of the steel sheet, and the average r value also decreases, so it is suppressed to 0.0050 wt% or less, more preferably 0.0030 wt% or less. . For even more stringent applications, it is desirable to make it 0.0015 wt% or less.
[0020]
In the present invention, in addition to the above basic components, at least one of Ni, Cr and Cu can be added in the range of 0.05 to 0.50 wt%.
Although Ni, Cr and Cu all have relatively small solid solution strengthening ability, the strength of the can can be increased by the fine grain strengthening mechanism. Such refinement of grain refinement is advantageous in that it does not impair neck-in moldability. In addition, the refinement of the structure is effective for improving the rough skin resistance. These effects can be expected if the addition amount of one or more of them is 0.05 wt% or more regardless of whether they are added individually or in combination. On the other hand, even if it is added over 0.50 wt%, it simply increases the cost, so it is limited to 0.50 wt% or less.
[0021]
Furthermore, in the present invention, in addition to the above basic components, Ti can be added in the range of 0.005 to 0.010 wt%.
Ti has the effect of raising the average r value of the steel sheet to a higher level, and at least 0.005 wt% or more is necessary. However, if it exceeds 0.010 wt%, the effect is saturated and the surface properties deteriorate. Limited to 0.010 wt% or less. In particular, when good surface properties are strictly required, the upper limit is preferably 0.008 wt%.
[0022]
The steel plate for cans according to the present invention is obtained by subjecting the slab having the above composition to cold rolling after hot rolling, then annealing, and then subjecting to temper rolling as necessary. It is important to adjust the average r value to 1.50 or more and the absolute value of Δr value to 0.30 or less.
That is, by increasing the average r value of the steel sheet, the drawing ratio in the first cup forming process is increased, the wrinkle suppressing pressure is increased, and the work hardening amount of the bottom portion is increased as compared with the conventional method. This increases the pressure resistance of the part. Therefore, it is necessary to increase the r value of the steel sheet, and there is a correlation with the yield stress of the steel sheet, but it is possible to increase the drawing ratio in the first cup forming process by setting the average r value to 1.50 or more. is there. In particular, in order to stabilize the molding process, the average r value is preferably 1.80 or more.
[0023]
In order to prevent the occurrence of ears (earring defects) in deep drawing, it is effective to reduce the Δr value of the steel sheet, and the absolute value of the Δr value is 0.30 or less, preferably 0.15 or less.
[0024]
Here, the average r value and Δr value were obtained by collecting JIS No. 5 test pieces from the rolling direction of the steel sheet, the direction of 45 ° with respect to the rolling direction, and the direction of 90 ° with respect to the rolling direction. The Rankford value in each direction was measured from the ratio of the strain in the width direction and the thickness strain when uniaxial tensile prestrain of ˜15% was applied, and was determined by the following equation.
r = (r _L + 2r _D + r _T ) / 4
Δr = (r _L −2r _D + r _T ) / 2
Here, r _L , r _D, and r _T represent the Rankford values in the rolling direction, the direction of 45 ° with respect to the rolling direction, and the direction of 90 ° with respect to the rolling direction, respectively.
In addition, when the uniform elongation of the steel plate was small and could not be measured by the above method, it was obtained by the natural vibration method in JIS G3135.
[0025]
In addition, as a specific method for adjusting the average r value of the steel sheet to 1.50 or more and the Δr value to 0.30 or less in absolute value, the hot rolling finish temperature is approximately Ar ₃ ± 50 ° C. using the steel having the above composition. In this range, the coiling temperature is approximately 540 to 680 ° C., the primary cold rolling reduction ratio is 85 to 90%, and the secondary cold rolling reduction ratio is less than 40%.
[0026]
Further, since the effect of the present invention becomes more prominent as the thickness of the steel plate becomes thinner, it is advantageous in practice to use a steel plate having a plate thickness of 0.30 mm or less, preferably 0.25 mm or less as a material for can manufacturing.
[0027]
The steel plate is used as it is or after being subjected to a surface treatment using the steel plate as an original plate, and then subjected to a can-making process. In addition, as surface treatment, normal electrotin plating, chromium plating, other plating treatments, and various coating treatments are advantageously adapted.
[0028]
In addition, although the conditions in the manufacturing process of a steel plate are not specifically limited, it can manufacture on the conditions shown below.
・ Slab reheating temperature: 1150 ~ 1300 ℃
-Finishing rolling temperature: (Ar ₃ transformation point -30 ° C) to (Ar ₃ transformation point + 100 ° C)
-Winding temperature: 450-650 ° C
・ Cold rolling reduction ratio: 83% or more ・ Annealing temperature: 700-800 ℃
-Temper rolling reduction after annealing: 1% or more (Yield point elongation exists in the annealed state and the material is not stable, so temper rolling of 1% or more is required except for special applications)
[0029]
The steel plate thus obtained is canned under the following conditions after being punched into a disc.
That is, in the first cup molding process, it is important that the drawing ratio is 1.80 or more, more preferably 1.85 or more. Conventionally, the conditions in this step have been set with a low drawing ratio of about 1.40 to 1.50, because the aluminum material having low workability has been set as a standard. However, in the present invention, a steel sheet having a high r value and good ductility is a target for drawing, so that forming with a high drawing ratio is possible. For example, even when the same blank diameter is adopted, by reducing the punch diameter and increasing the drawing ratio, the distortion of the bottom portion is increased to increase the pressure resistance of the can body, particularly the bottom portion. Application of such a technique is realized only when a high r value and good ductility are imparted to a steel plate as a material.
[0030]
Moreover, since the work hardening can be expected by setting the thickness reduction rate of the bottom part to 10% or more, the pressure resistance of the bottom part can be further increased. At the same time, increasing the thickness reduction rate of the bottom portion leads to substantial thinning of the can body, and is effective in reducing the weight of the can. The above effects can be expected to further expand by setting the thickness reduction rate of the bottom portion to 15% or more.
Here, as a specific method for increasing the thickness reduction rate of the bottom portion, it is effective to strengthen wrinkle suppression and increase the shoulder radius of the punch.
[0031]
The first cup thus obtained is subsequently subjected to redrawing and ironing. By increasing the drawing ratio in this redrawing process, the same effect as described above can be obtained. However, in this redrawing process, it is difficult to control the wrinkle restraining force, and it is difficult to apply in the current apparatus. However, if the wrinkle restraining force can be controlled, it is possible to increase the pressure resistance of the bottom portion.
[0032]
Accordingly, the redrawing and ironing may be performed under normal conditions, for example, blank → 140 mmφ → first cup forming with 77 mmφ punch → redrawing with 68 mmφ punch → three stages of ironing.
[0033]
【Example】
Example 1
After melting the steel having the component composition shown in Table 1 in a converter, the obtained slab was reheated to 1250 ° C. and hot finish rolling was completed in a temperature range of 860 to 950 ° C. The finish rolling temperature was controlled so as to fall within the range of (Ar ₃ transformation point−20 ° C.) to (Ar ₃ transformation point + 50 ° C.) according to each steel composition. Next, after winding at a winding temperature of 640 ° C., pickling was performed, and then cold rolling with a reduction ratio of 90% was performed to obtain a 0.22 mm cold-rolled sheet.
[0034]
Further, each cold-rolled sheet was annealed at 760 ° C. for 30 s in a continuous annealing furnace, rapidly cooled to 340 ° C. at a cooling rate of 30 ° C./sec, and subjected to light pressure of 2 to 6%.
Thereafter, # 25 tin plating treatment was continuously performed on a halogen-type electric tin plating line to obtain a cover plate. Table 2 shows the results of investigations on the tensile properties of the obtained cover plate. The tensile properties were evaluated by a test using a JIS No. 5 test piece.
[0035]
Next, 350 ml cans were produced with each tinplate. That is, the first cup was formed by drawing with a drawing ratio of 1.95 to 2.05. Specifically, the blank diameter was changed from 138 to 143 mm and the punch diameter was changed from 71 to 86 mm. Moreover, the wrinkle restraining force was adjusted so that the thickness reduction rate of the bottom part of the cup was 13 to 18%. Thereafter, redrawing and three-step ironing were continuously performed with a punch diameter of 68 mm.
[0036]
The results of investigation on the pressure resistance at the bottom of the can thus obtained are shown in Table 2 together with the results of investigation on non-earring property and neck-in formability in redrawing.
[0037]
Here, the bottom portion pressure resistance was evaluated based on the limit pressure at which the hydrostatic pressure was loaded into the can and the bottom buckled.
In addition, the non-earring performance is fast cupping, the difference between the height of the peak and the height of the valley from the cup bottom is obtained and compared in terms of size, and compared with the current material. The NG was evaluated as NG, and the same or superior one was evaluated as OK.
Furthermore, neck-in formability is evaluated by performing neck-in processing from 211 mm diameter to 206 mm diameter with a four-stage neck and comparing the molding load at that time, and those with higher molding load than the current material. NG, equivalent or low was set as OK.
[0038]
[Table 1]

[0039]
[Table 2]

[0040]
From the results shown in Table 2, it can be seen that if cans were made according to the method of the present invention, a sufficiently high bottom pressure resistance was obtained without sacrificing other characteristics. Moreover, when the obtained can was observed, it was confirmed that the can obtained according to the present invention had good surface properties and corrosion resistance, and also had good cold rolling properties in the intermediate process.
[0041]
Example 2
After melting the steel having the composition shown in Table 3 in a converter, a thin steel plate and a tin-plated steel plate were produced under the production conditions shown in Table 4, and then various characteristics were evaluated in the same procedure as in Example 1. The results are shown in Table 5. In addition, the average r value of the steel plate manufactured on the conditions shown in Table 4 was 1.85, and (DELTA) r value was 0.05 in absolute value.
[0042]
[Table 3]

[0043]
[Table 4]

[0044]
[Table 5]

[0045]
From the results shown in Table 5, it can be seen that by making cans according to the present invention, a sufficiently high bottom pressure resistance was obtained without sacrificing other characteristics. Further, when the redrawing process and the ironing process were observed in detail, in the process according to the present invention, the removal from the punch during molding, so-called stripping, was also improved. As a result of detailed experiments on this point, it has also been found that the occurrence rate of dropout defects is reduced to 1/3 compared with the conventional method.
[0046]
【The invention's effect】
According to the method of the present invention, it is possible to form a DI can by taking advantage of the good formability of an ultra-low carbon steel sheet, and achieve a sufficiently high bottom pressure strength. In addition, according to the method of the present invention, other can-making characteristics such as non-earring property, neck-in formability and stripping property are also excellent.
For this reason, DI can can be manufactured by using specific ultra-low carbon steel manufactured for automobiles and optimizing the manufacturing conditions, so the number of steel types in the steel making process can be reduced and the manufacturing cost can be reduced. .

Claims (3)

C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S: 0.010 wt % or less and N: containing 0.0050% or less, the balance has a chemical composition consisting of Fe and unavoidable impurities, were adjusted with an average r value 1.50 or more, and the Δr value in absolute value to 0.30 or less thickness Using a steel sheet with a thickness of 0.30 mm or less as a material, after punching the material, drawing is performed under the conditions of drawing ratio: 1.80 or more and bottom thickness reduction: 10% or more, then redrawing and ironing A method for producing a lightweight can excellent in bottom pressure strength. C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S: 0.010 wt % And N: 0.0050 wt% or less, further containing at least one of Ni: 0.05 to 0.50 wt%, Cr 0.05 to 0.50 wt% and Cu: 0.05 to 0.50 wt%, with the balance being Fe and A steel plate having a chemical composition composed of inevitable impurities, an average r value of 1.50 or more, and a Δr value adjusted to an absolute value of 0.30 or less and a thickness of 0.30 mm or less, after punching the material, A lightweight can with excellent bottom pressure resistance, which is drawn under the conditions of drawing ratio: 1.80 or more and thickness reduction ratio of the bottom: 10% or more, and then redrawing and ironing. Method. C: 0.0005 to 0.0050 wt%, Si: 0.20 wt% or less, Mn: 0.05 to 1.00 wt%, Al: 0.005 to 0.100 wt%, Nb: 0.003 to 0.020 wt%, P: 0.100 wt% or less, S: 0.010 wt% % And N: 0.0050 wt% or less, further containing Ti: 0.005 to 0.0100 wt%, the balance having a chemical composition consisting of Fe and inevitable impurities, an average r value of 1.50 or more, and a Δr value Using a steel sheet with a thickness of 0.30 mm or less adjusted to an absolute value of 0.30 or less as a raw material, after drawing the material, the drawing process is performed with the drawing ratio: 1.80 or more and the bottom thickness reduction ratio: 10% or more. A method for producing a lightweight can excellent in bottom pressure strength, characterized by being applied below, followed by redrawing and ironing.