JPS61235547A - Manufacture of deep-drawn closure - Google Patents

Abstract

PURPOSE:To enable the manufacture of deep-drawn closure excelling in strength by hot-rolling and cold-rolling an Al alloy ingot containing specific amounts of Fe, Si and Cu and by subjecting the resulting rolling-tempered sheet to baking finish and then to deep drawing twice or more. CONSTITUTION:The Al alloy ingot containing, by weight, 0.6-2.0% Fe, 0.3-1.0% Si, and 0.05-2.0% Cu is subjected to soaking treatment, hot rolling, process annealing, cold rolling and then annealing, which is cold-rolled at 50-90% final cold draft to form a rolling-tempered sheet of prescribed thickness. The rolling-tempered sheet is subjected to baking finish as closure and then to work ing of >=2.2 total drawing ratio by two-time or more deep drawing so as to obtain the deep-drawn closure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a deep-drawn closure in which the drawing process is performed two or more times to achieve a total drawing ratio of 2.2 or more, and particularly relates to a method for manufacturing a deep-drawn closure in which the drawing process is performed two or more times to achieve a total drawing ratio of 2.2 or more. This made it possible to manufacture deep-drawn closures with improved properties and high strength.

[Conventional technology]

Traditionally, JISlloo (AI) was used to manufacture closures.
-0.05~0.20wt%Cu alloy) or JIS 3
003 (A 1-0.05~0.20wt%Cu −
1,0 to 1,5 wt% Mn alloy) with a cold working degree of less than 50%, an annealing tempered plate with a cold working degree of 50% or more, and painting and baking. After applying
Closures with a total drawing ratio of less than 2.2 are manufactured by one drawing process, while deep-drawing closures with a total drawing ratio of 2.2 or more are manufactured by performing the drawing process two or more times.

[Problem that the invention seeks to solve]

However, if the drawing process is carried out twice or more to produce a deep-drawn closure with a total drawing ratio of 2.2 or more, the drawing processability after the second drawing process cannot be said to be good. Processing is carried out to the drawing ratio, and the drawing ratio is kept as low as possible in the second drawing process, or a third drawing process is added to this, but not only is it easy to break due to slight fluctuations in the forming conditions, It has the disadvantage of high manufacturing cost.

In addition, since rolled tempered plates, annealed tempered plates with a cold working degree of less than 50%, or annealed tempered plates with a cold worked degree of 50% or more are used, the strength of the resulting deep drawn closure is low ( In applications where pressure is applied to seal the product, blistering may occur.
There are drawbacks such as a low opening torque value, which makes it difficult to reduce the thickness of deep-drawn closures.

[Means for solving problems]

In view of this, as a result of various studies, the present invention has developed a method for manufacturing a deep-drawn closure that eliminates the above-mentioned drawbacks.
0.6-2.0wt% (hereinafter wt% is abbreviated as single %)
, 3i 0.3~1.0%, CuO805~2.0%
After applying paint baking to a rolled and tempered plate with a degree of cold working of 50 to 90%, consisting of A, e and normal impurities,
It is characterized in that the drawing process is performed twice or more to achieve a total drawing ratio of 2.2 or more.

That is, in the present invention, an alloy ingot having the above composition is subjected to soaking treatment, hot rolling, intermediate annealing, and cold rolling according to a conventional method, and after annealing, cold rolling is performed with a degree of cold working of 50 to 90%. A rolled tempered plate with a predetermined thickness is obtained. Next, this rolled and tempered plate is painted and baked as a closure, and then drawn twice or more to obtain a total drawing ratio of 2.2 or more to form a deep drawn O-jar.

[For production]

The reason why the alloy composition is limited as described above in the present invention is as follows.

Fe and 3i are co-contained in order to prevent the occurrence of flow marks and rough skin in deep-drawn closures, and to improve tearing properties when opening the closure.Fe content is reduced to 0.
．． The reason why we limited the Si content to 6 to 2.0% and 0.3 to 1.0% is that sufficient effects can be obtained even if the Fe content is less than 0.6% and the S1 content is less than 0.63%. First, if the Fe content exceeds 2.0%, giant compounds are generated during casting, reducing workability, and if the S1 content exceeds 1.0%, drawing workability is reduced. Furthermore, the total content of Fe and Si is 3.0%.
This is because if it exceeds this, the heat resistance will decrease, and the paint baking of the closure will sometimes cause recrystallization, which will significantly reduce the drawing workability from the second time onwards.

Cu is added to improve heat resistance and strength without impairing corrosion resistance, and the Cu content is reduced to 0.05.
The reason for limiting the Cu content to 2.0% is that if the Cu content is less than 0.05%, a sufficient effect cannot be obtained, and if it exceeds 2.0%, the corrosion resistance will be significantly lowered.

Next, for the alloy with the above composition, the final cold working degree is 50 to 90.
% rolled and tempered plate is used in order to increase the strength by cold working and at the same time reduce the work hardening index n value to improve the drawability for two or more times, and the degree of cold working is 50%. If it is less than 90%, a sufficient effect will not be obtained, and if it exceeds 90%, the occurrence of deep drawing selvages will increase, and the paint as a closure will be easily softened by baking, reducing the drawing workability after the second drawing.

Example (1) An alloy having the composition shown in Table 1 was melted and cast by a conventional method, soaked, and then hot rolled to a thickness of 4.5 mm. Oa
After forming the plate into a sheet with a thickness of
．． It was cold rolled to 9am.

This was re-annealed at 360° C. and then cold-rolled to a thickness of 0.25 mm to obtain a rolled tempered plate with a workability of 12%. After painting and baking the rolled plate as a closure in the usual manner, drawing tests were conducted twice to determine the critical total drawing ratio. The results are also listed in Table 1.

As is clear from Table 1, although the present invention method NQ1 shows a limit double drawing ratio of 1.59 and a limit total reduction ratio of 3.2, the comparative method NQ1 has a Fe or Si content that deviates from the alloy composition of the present invention. It can be seen that the limit double drawing ratio and the limit total drawing ratio are inferior in all cases of 3 to 3.

Example (2) An alloy consisting of 15% CLlo, 0.8% Fe, 0.5% 3i, and the balance Aλ was melted and cast by a conventional method, soaked, and then hot rolled to a thickness of 5. After forming an O#II plate, it was intermediately annealed at 360°C, then cold rolled to a thickness having the final cold working degree shown in Table 2, and then re-annealed at 360°C to a thickness of 0. Cold rolled to 25M. After painting and baking the rolled and tempered plate in the same manner as in Example (1), drawing tests were conducted twice to determine the critical total drawing ratio. The results are also listed in Table 2.

As is clear from Table 2, the degree of cold working is 50°70,9
Methods 14Q5-7 of the present invention using 0% rolled and tempered plates show high critical double draw ratios and critical total draw ratios. On the other hand, comparative method 110 using a rolled heat-treated plate with a degree of cold working of 40%
At No. 8, the work hardening index n value is large, and the limit double drawing ratio decreases significantly.

Furthermore, it can be seen that in Comparative Method 9, which uses a rolled and tempered plate with a degree of cold working of 95%, the deep drawing selvage becomes extremely large.

Example (3) An alloy having the composition shown in Table 3 was melted and cast in the same manner as in Example (1), followed by soaking treatment, hot rolling, and intermediate annealing.
After cold rolling to the final cold working degree shown in Table 3 and re-annealing it at 360°C, it was rolled to a thickness of 0.25 m
Cold rolled to

After the coating was baked, a drawing test was conducted twice to determine the limit total drawing ratio. These results can be used as rolled tempered plates with a degree of cold working less than 50%, annealed tempered plates with a degree of cold worked of less than 50%, or
A comparative method using an annealed tempered plate of 0% or more and a comparison with the conventional method are also listed in Table 3.

As is clear from Table 3, which of the conventional methods 22 to 26 using rolled tempered plates with a degree of cold working of less than 50%, annealed tempered plates with a degree of cold working of 50% or more, Also, the limit double draw ratio and limit total draw ratio are low, and the resulting closure has low strength. On the other hand, in the method of the present invention Nα10 to Nα15 using rolled tempered plates with a degree of cold working of 50 to 90%, the limit two drawing ratio and the limit total drawing ratio are both large, and the resulting closures have high strength.

On the other hand, Comparative Methods Nα16 to 19, which have different alloy compositions, and Comparative Method NQ20, which has a low degree of cold working, do not improve the limit double drawing ratio and limit total drawing ratio, while Comparative Method NQ21, which has a high degree of cold working, Although the critical total drawing ratio and the strength of the resulting closure are improved, the occurrence of selvage during drawing becomes large, making it unsuitable for drawing.

〔Effect of the invention〕

In this way, the present invention improves the drawing workability of two or more times, and not only can the process that conventionally requires three steps be completed in two steps, but also the rolling process with a degree of cold working of 50 to 90% is possible. Since the heat-treated plate is used, the strength of the closure is high, no blistering occurs even when internal pressure is applied, and furthermore, the closure can be made thinner, which provides remarkable industrial effects.

Claims (1)

[Claims] Fe0.6-2.0wt%, Si0.3-1.0wt%
A rolled and tempered plate with a final cold working degree of 50 to 90%, containing 0.05 to 2.0 wt% of Cu and the balance Al and normal impurities, is painted and baked, and then drawn twice or more. A method for manufacturing a deep-drawn closure characterized by performing processing with a total drawing ratio of 2.2 or more.