JPH02118048A - Al alloy sheet for ringpull gap - Google Patents

Abstract

PURPOSE:To manufacture the title alloy sheet capable of thinning, in an Al alloy sheet contg. specific ratios of Mg and Fe, by specifying the areal rate of intermetallic compounds after rolled in the surface. CONSTITUTION:An ingot is manufactured from the molten metal of an Al alloy contg., by weight, 0.5 to 2.1% Mg, 0.25 to 0.55% Fe and the balance Al with inevitable impurities. The ingot is faced, is, at need, subjected to homogenizing treatment and is subjected to hot and cold rolling into prescribed sheet thickness to prepare an Al alloy sheet contg. intermetallic compounds of 1 to 4% areal rate in the surface. Furthermore, by weight, about 0.05% Ti and about 0.005% B can preferably be incorporated into the Al alloy sheet, and all of Si, Cu, Zn, etc., as impurities are regulated to about <=0.3wt.%. In this way, the Al alloy sheet for a ringpull cap having no generation of breaking in a neck even when thinned and having good openability can be obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to the case where soft drinks etc. are sold in bottles etc.
This invention relates to an Al alloy plate used in the ring pull cap used as the lid.

[Conventional technology]

In recent years, ring pull caps have been widely used as caps for enclosing soft drinks and the like in bottles. There are various types of ring pull caps, such as lip camp, maxi cap, and pull up cap, but the common structural feature of these is that they have cut grooves called scores on the top or side of the cap. When in use, the cap is opened by hooking one's finger on a ring part formed integrally with the cap and pulling up the ring to tear the cap along the score part.

Conventional materials for such ring pull caps include:
It35052A 1 alloy plate with moderate strength and formability (2,2~2.8v1%Mg-0,15~0.35m
1% Cr-Al1 was used exclusively.

[Problem to be solved by the invention]

However, with the recent rise in the price of Ai, there has been a strong demand for thinner A7 alloy plates for ring pull caps, and in response to this, the thickness of the JI35052A 1 alloy plate has been increased from the conventional 0.25mm to 0.20mmf.
Considerations were made to make it as thin as ff degrees.

However, with the thinner Its 5052Af alloy plate, the sign part of the ring may be bent when opened due to lack of rigidity. +1 light. The cause of this is that due to the thinner wall, the bending rigidity of the neck becomes smaller than the opening resistance, which is the force required to tear off the score, and when opening the bottle, the neck is subjected to an excessive bending load that is greater than it can withstand. This is because . If this bending occurs, it becomes extremely difficult to open the bottle, and in extreme cases, the neck may break, making it impossible to open the bottle, which is a serious problem.

Therefore, the stronger IIS 5H2Aj! Alloy plate (
40-5. The use of OWI%~1g-Al) was considered, but in this case, although the rigidity of the nail part was certainly improved, the resistance to opening the cap increased even more, so the force required to open the cap would be extremely large. It has become clear that a new problem arises in that it becomes extremely difficult to open the bottle.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention provides an Al alloy plate for a ring pull cap that does not cause bending of the neck when opening the cap even when the thickness is made thinner, and which also exhibits good performance when opening the cap.

That is, in the present invention, M g 0.5 to 2.1 wt% and Fe
025~0.55wt! The aluminum alloy is characterized in that the area ratio of intermetallic compounds after rolling on the surface of an Al alloy consisting of aluminum and unavoidable impurities is 1 to 4%.

[For production]

Next, the reason why the alloy components are limited as described above in the present invention will be explained.

The purpose of adding Mg is to improve the strength, particularly to increase the rigidity of the neck portion and to provide pressure resistance sufficient to withstand the internal pressure of the enclosed contents. And the Mg content is 0.5vt% (hereinafter W1% is simply written as %) to 2.1%
The limit was 0. If the strength is less than , the strength is insufficient.
This is because if it exceeds 2.1%, the opening performance deteriorates and it becomes difficult to open the cap, and the neck becomes more likely to bend due to increased opening resistance.

Fe is an element that forms an Al-Fe based intermetallic compound, and this intermetallic compound has the effect of facilitating the generation and propagation of cracks when the cap is opened. Therefore, the addition of Fe has the effect of improving the openability.

The reason why the Fe content is limited to 0.025% to 0.55% is to make the area ratio of intermetallic compounds 1 to 496 when the surface of this alloy is observed after rolling.

That is, if Fe is less than 0.025%, the surface f of the intermetallic compound]
! The area ratio of intermetallic compounds is less than 1%, which is insufficient to exhibit the above effects, and when it exceeds 0.55%, the area ratio of intermetallic compounds exceeds 4%, making cracking too sensitive, such as This is because the problem of breakage at the notched portion of the score is likely to occur.

Therefore, in order to make the area ratio of the intermetallic compound in the range of 1 to 4%, the content of Fe should be in the range of 0.25 to 0.55%.

Next, a method for manufacturing the Al alloy plate of the present invention will be explained.

A molten Al alloy having the above composition may be made into an ingot using a conventional method, subjected to homogenization treatment as necessary before and after the surface, and finished to a predetermined thickness by hot and cold rolling. In order to adjust the strength of this rolled plate to a desired level, intermediate annealing may be performed during cold rolling, or final annealing may be performed after cold rolling. In order to refine the crystal grains of the ingot and make the structure uniform, Ti and B were added to 0.005% and 0.005%, respectively.
It is desirable to add 0[15% or less, and furthermore, if Si, Cu, Zn, etc. as impurities are all 0396 or less, the effects of the present invention will not be impaired.

〔Example〕

Next, examples of the present invention will be described.

An Al alloy having the composition shown in Table 1 was melted and cast, and 550
After homogenization treatment at ℃ for 5 hours, the plate thickness was reduced to rlm by hot rolling.
It was set as m. Subsequently, it was cold rolled to 0.3wa, intermediate annealed at 320°C for 4 hours, and then final cold rolled to a plate thickness of 0.25+ni+ or 0.20ff+m.

Afterwards, both sides of these cold-rolled plates were painted to create a diameter of 38 m.
It was press-formed into a ring pull cap of size m, and then wrapped and tightened around the mouth of the bottle.

For such ring pull caps, we measured the opening load and the presence or absence of bending at the neck part as follows. At the same time, we observed intermetallic compounds on the surface of the cold rolled plate using an optical microscope and analyzed them using an image analysis device. The area ratio was measured and these results are also listed in Table 1. Note that the appropriate value for the opening load in the table is 2 to 3 kg1.

In other words, the load (
The cap-opening resistance) was measured to determine the cap-opening load, and at this time, the presence or absence of bending at the neck was observed.

As is clear from Table 1, the alloy plates Nα1 to Nα of the present invention
It can be seen that No. 4 indicates an appropriate opening load, and no bending of the neck portion has occurred.

On the other hand, comparative alloy sheet N (15 to Nα
9, the opening load is too large, the neck bends, or score cracking occurs during press working. In addition, the conventional alloy plate using Moon 55052 alloy is good when the plate thickness is 0.25 mm (klO), but when the plate thickness is reduced to 0.20 mm (Nnl++), bending of the neck occurs, and when using II350H alloy, The opening load of the conventional alloy plate Nα12°Black 13 used was too high.

〔Effect of the invention〕

As described above, according to the present invention, Al for the ring pull cap
Even if the alloy plate is made thinner than before, the neck does not bend when opening the bottle, and the opening performance is good, which brings about remarkable industrial effects.

Claims (1)

[Claims] (1) Mg0.5~2.1wt% and Fe0.25~
An Al alloy plate for a ring pull cap, characterized in that the area ratio of intermetallic compounds after rolling on the surface of an Al alloy containing 0.55 wt% and the remainder Al and inevitable impurities is 1 to 4%.