JP2964695B2 - Plating steel sheet for DI can - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a two-piece can (Draw) in which a steel plate punched into a circular shape is formed into a cup shape by drawing, and the side wall is thinned by ironing.
n and Ironed Can).

[0002]

2. Description of the Related Art As a material for a two-piece can (hereinafter referred to as a DI can), an aluminum plate and a tin plate (tin-plated steel plate) are used. In the first stage of DI can processing,
First, a steel plate is punched into a circular shape, and is formed into a cup shape by drawing (Drawn). Further, the primary cup molded product is molded into another smaller-diameter cup (Redrawn).
Next, this secondary cup molded product is passed through an ironing die,
The body side wall is squeezed between the die and the punch, and the body length is increased (Ironing) while reducing the wall thickness to obtain a can having a predetermined length.

[0003] As described above, the cans manufactured by DI molding have a smaller wall thickness at the can wall (body portion) than at the can bottom. There is an advantage that the amount of material used can be reduced.

[0004] However, the conventional DI can cannot be used for vacuum depressurizing cans that are vacuum-tightened because the wall thickness of the can wall is small and the strength of the body is weak. It is mainly used for beverage cans that generate positive pressure such as carbonated beverages.

[0005] As described above, DI cans are advantageous in terms of cost because they use a small amount of raw materials, tend to increase in demand, and are expected to expand applications in the future. Tinplate has attracted attention because of its cost advantage when compared with aluminum and tinplate.

However, in the manufacturing process of the DI can, since the severe processing is performed as described above, the material is required to have excellent moldability. In recent years, in order to improve productivity, DI molding has been required to further increase the speed, and a material having better moldability than before has been required. In this regard, the tinplate material has a function of a lubricant at the time of ironing, while ensuring that the Sn plating layer has corrosion resistance.
It is a suitable material for steel plates for cans.

[0007]

However, although the conventional tinplate material can be DI-formed up to a certain speed, the Sn-plated layer melts due to heat generated during the forming process when the can is made at a higher speed. However, there is an inconvenience that the can is burned on the die. In addition, there is a disadvantage that the partial melting of the Sn plating layer causes unevenness in the gloss of the can wall, thereby impairing the beautiful appearance.

[0008] JP-A-1-132778 discloses Sn
Zn, Ti, Ni with a melting point higher than the melting point of
After plating a metal such as
I cans are described. Thus, by forming the plating layer of the high melting point metal, the can-making speed can be raised without burning.

However, since metals having relatively high melting points, such as Zn, Ti, and Ni, are harder materials than Sn, the work energy required for the forming process is significantly increased as compared with the tin material, and the energy is increased. It is uneconomical in terms of cost and equipment cost.

[0010] Japanese Patent Application Laid-Open No. 1-111853 discloses Sn
After plating, a molten Al can is described. According to this, Al has a softness substantially close to Sn, so that the forming energy can be suppressed to a low level in terms of workability.

However, in such a coating structure of a DI can, when the speed of the can is increased, the temperature of the can exceeds the melting point of Sn, and the alloying of the underlying Sn layer and the iron base material occurs. The reaction proceeds, and gloss unevenness occurs due to the formation of the FeSn alloy layer. As a result, the canning speed cannot be increased beyond a certain speed, and the productivity cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a plating method for a DI can that can be manufactured at a high speed and can be formed with a small processing energy required for a tinplate. The purpose is to provide steel sheets.

[0013]

A plated steel sheet for a DI can according to the present invention comprises: an intermediate film made of an AlSn alloy or Al having a thickness of 0.05 to 5 μm formed on a surface to be an outer surface of the can for a steel sheet for a can; Film thickness further formed on this intermediate film
It is characterized by having a Sn layer of 0.04 to 2 μm and a Sn plating layer formed on a surface to be an inner surface of a steel plate for a can. In this case, the Sn content in the AlSn alloy intermediate film is preferably 50% by weight or less.

[0014]

In the plated steel sheet for DI cans according to the present invention, the intermediate film made of AlSn alloy or Al is formed between the Sn layer on the outer surface of the can and the steel sheet base, so that the frictional heat generated by the high-speed can makes. Even if the can body is overheated, the diffusion of the Sn layer to the Fe substrate side is effectively prevented by the presence of the intermediate film, and alloying of Sn and Fe does not occur on the outer surface of the can.

The effect of suppressing the alloying of Sn and Fe is remarkably exhibited when the Sn content in the intermediate film is set to 50% by weight or less. When the Sn content in the intermediate coating is increased,
Sn melts out of the AlSn alloy during molding,
The molding energy is reduced by the lubrication effect of the eluted Sn.
Is reduced. However, when the Sn content exceeds 50% by weight, the eluted Sn reacts with Fe to form an alloy, resulting in uneven gloss. For this reason, the Sn content in the intermediate coating is desirably 50% by weight or less.

When the intermediate film does not contain Sn and the intermediate film is formed only of Al, the effect of suppressing FeSn alloying is maximized, and is most preferable from the viewpoint of preventing the occurrence of gloss unevenness.

If the thickness of the intermediate coating is less than 0.05 μm, it is not possible to sufficiently suppress the alloying of FeSn. Therefore, the thickness of the intermediate coating must be at least 0.05 μm. On the other hand, an intermediate coating having a thickness of more than 5 μm is unnecessary from a technical point of view and uneconomical from a manufacturing point of view.

Further, since the forming energy is increased only with the Al-containing intermediate film, an Sn layer is required thereon. The thickness of the upper Sn layer improves lubricity,
From the viewpoint of reducing molding energy, the thickness needs to be 0.04 μm or more. As the Sn layer becomes thicker, the lubricity at the time of can making improves, but when the thickness exceeds 2 μm, the lubricity improving effect is saturated. Therefore, a Sn layer having a thickness exceeding 2 μm is unnecessary from a technical point of view and is uneconomical from a manufacturing point of view.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings and tables.

As shown in FIG. 1, a basic structure of a plated steel sheet for DI can 2 according to an embodiment of the present invention is such that an intermediate film 4 made of an AlSn alloy is formed on one surface of a base material 3 made of a steel sheet. While the Sn plating layer 5 is formed thereon,
The Sn plating layer 5 is directly formed on the other surface of the substrate 3 by plating. Next, the results of manufacturing various tin-plated steel sheets and examining various characteristics of each of them will be described with reference to Table 1. Example 1 (Production method type A)

Using a vacuum evaporation apparatus equipped with two water-cooled copper crucibles, one side of a low carbon aluminum killed steel sheet having a thickness of 0.29 mm
Six types of samples 1 to 6 having different plating compositions and plating thicknesses were produced by Sn co-evaporation plating or Al evaporation plating. For each of the vapor-deposited plating layers, sample 1 was 2μ thick.
m, an Al layer having a thickness of 2 μm, an AlSn alloy layer having a thickness of 2 μm (Sn 0.5% by weight), and a sample 3 having an Al layer having a thickness of 4.5 μm.
Sn alloy layer (Sn 10% by weight), sample 4 is 1.8 μm thick
m, an AlSn alloy layer (Sn21% by weight), sample 5 was a 3.2 μm thick AlSn alloy layer (Sn33% by weight), and sample 6 was a 0.5 μm thick AlSn alloy layer (Sn50% by weight).
And

Further, S is applied to both sides of each sample in the same apparatus.
An n plating layer was formed. The thickness of each Sn plating layer was 1.3 μm for sample 1, 1.0 μm for sample 2,
Is 0.5 μm, sample 4 is 1.0 μm, sample 5 is 0.3
μm and 1.5 μm for sample 6. After Sn plating, each sample was treated with sodium dichromate solution (20g / l)
About dipped for 1 second in the CrO _X film about 1 mg / m ² Granted. After the chemical conversion treatment, a test piece of a predetermined size was punched out, and a DI can formability evaluation test described later was performed. Example 2 (Production method type B)

A low carbon aluminum killed steel sheet having a thickness of 0.29 mm is degreased and pickled, then immersed in a molten metal bath in which Al and Sn are mixed and dissolved, and AlSn alloy plating layers of various compositions and thicknesses are coated on the surface of the steel sheet. Formed. In each of the hot-dip plating layers, Sample 7 was a 2.5 μm thick AlSn alloy layer (Sn
5% by weight), Sample 8 was a 1.5 μm thick AlSn alloy layer (Sn 18% by weight), and Sample 9 was a 3.0 μm thick Al
Sn alloy layer (Sn 24% by weight), sample 10 has a thickness of 4.3
μm AlSn alloy layer (Sn 31% by weight), sample 11
Was an AlSn alloy layer (Sn 40% by weight) having a thickness of 1.0 μm.

Thereafter, Sn plating layers were formed on both surfaces of each sample under normal tin plating conditions (ferrostan bath).
The thicknesses of the Sn plating layers were 1.4 μm for Sample 7, 1.0 μm for Sample 8, 0.2 μm for Sample 9, and 1 μm for Sample 1.
0 was 0.5 μm, and Sample 11 was 1.5 μm. After the Sn plating treatment, a chemical conversion treatment similar to that of the above-described Example 1 was performed. Thereafter, a test piece of a predetermined size was punched from each sample.
A DI can formability evaluation test described below was performed. Comparative Example 1 (Production method type A)

In the same manner as in Example 1, four types of samples 12 to 15 having different compositions and thicknesses of the intermediate coating film were produced. Each of the vapor-deposited plating layers has a thickness of Sample 12.
2.5 μm AlSn alloy layer (Sn 62 wt%), sample 13 is 4.5 μm thick AlSn alloy layer (Sn 80 wt%), sample 14 is 0.03 μm thick AlSn alloy layer (Sn 21 wt%), sample 15 is thick 2.0 μm Al
This was a Sn alloy layer (Sn 65% by weight).

Thereafter, Sn plating was performed on both surfaces of each sample under normal tin plating conditions (ferrostan bath). The thickness of the Sn plating layer was 1.5 μm for sample 12 and 1.5 μm for sample 12.
3 is 0.7 μm, sample 14 is 1.3 μm, sample 15
Was set to 1.2 μm. After the Sn plating, a chemical conversion treatment similar to that described above was performed, a test piece having a predetermined size was punched out, and a DI can formability evaluation test described later was performed. Comparative Example 2 (Production method type C)

A low-carbon aluminum-killed steel sheet having a thickness of 0.29 mm was degreased and pickled, and then Sn-plated on both sides of each sample under ordinary tin plating conditions (ferrostan bath). The thickness of the Sn plating layer was 0.4 μm for sample 16 and
Was 1.0 μm and Sample 18 was 0.8 μm. After the Sn plating treatment, the same chemical conversion treatment as described above was performed, a test piece of a predetermined size was punched out, and a DI can formability evaluation test described later was performed. Comparative Example 3 (from manufacturing method type C to type B)

Samples 19 and 2 were prepared under the same conditions as those of Samples 16 and 18 of Comparative Example 2, respectively.
No. 0 was electroplated with tin, and then immersed in a molten metal bath in which Al was dissolved to perform Al plating. Al
The thickness of each plating layer was 1.5 μm for sample 19 and 3.0 μm for sample 20. After the Al plating treatment, the same chemical conversion treatment as described above was performed, a test piece of a predetermined size was punched out, and a DI can formability evaluation test described later was performed. Comparative Example 4 (Production method type A)

After Ni was vapor-deposited and plated on one surface of the sample 21 under the same conditions as in Example 1, this was immersed in a molten metal bath in which Al was dissolved, and Al plating was performed. The thickness of the Ni deposited plating layer is 1.0 μm, and the thickness of the Al plating layer is 1.5 μm
And After the Al plating treatment, the same chemical conversion treatment as described above was performed, a test piece of a predetermined size was punched out, and the following DI can formability evaluation test was performed. Next, the DI can formability evaluation test will be described.

A disk having a diameter of 123 mm was punched from each of the sample steel plates, and these were punched with a commercially available cupping press to obtain an inner diameter of 72 mm.
Each was molded into a 36 mm high cup. Next, each molding cup was charged into a DI machine, and the punch was reflowed at a speed of up to 50 m / min and a stroke length of 600 mm while circulating a refrigerant at 40 ° C. Further, these were subjected to three-stage ironing to obtain DI cans. In this case, the molding speed of Samples 1 to 14, 16, 17, and 19 to 21 was 45 m / min, and the molding speed of Samples 15 and 18 was 30 m / min. Each of the DI cans has an inner diameter of 52 mm and a height of 130 mm, and the thickness of the can body is about 0.12 mm
Until thin.

The evaluation of the DI formability was performed by calculating the forming energy required for the DI forming from the forming load and the deformation amount, and based on the magnitude of the value. As shown in Table 1, all of the samples 1 to 11 of the examples obtained results showing molding energy values equal to or lower than the tinplate. Thus, with the plated steel sheet of the present invention, cans can be manufactured at high speed with low forming energy.

The appearance test of the body of each sample can was carried out by visual observation.
4, 16, 17, 19, and 20 each had uneven gloss, but none of Samples 1 to 11 of the examples had any uneven gloss.

As is clear from the results of Comparative Example 1, Al
When the Sn content in the Sn alloy coating exceeds 50% by weight, the forming speed is increased from high speed (45 m / min) to low speed (30 m / min).
It can be seen that unevenness in gloss occurs if the sample is not dropped. Also,
The same can be said from the results of Comparative Example 2;
With the conventional tinting materials of Nos. To 18, high-speed cans cannot be produced without causing uneven gloss. Further, the same can be said from the results of Comparative Example 3, and Samples 19 and 20 cannot be manufactured at high speed without uneven gloss. In Sample 21 of Comparative Example 4, gloss unevenness did not occur during high-speed can-making, but the molding energy value was greatly increased.

[0034]

[Table 1]

[0035]

According to the plated steel sheet for DI cans of the present invention, cans can be manufactured at high speed without seizure, and can be formed with a small processing energy required for tinplate. . Therefore, a DI can having a beautiful appearance without gloss unevenness can be manufactured at a high speed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a plated steel sheet for a DI can according to an embodiment of the present invention.

[Explanation of symbols]

 3; substrate, 4; intermediate coating, 5; Sn plating layer

Claims (2)

(57) [Claims] 1. An intermediate film made of an AlSn alloy or Al having a thickness of 0.05 to 5 μm formed on a surface to be an outer surface of a can of a steel sheet for a can, and a film further formed on the intermediate film.
A plated steel sheet for a DI can having a Sn layer of 0.04 to 2 μm and a Sn plated layer formed on a surface to be an inner surface of the can for a steel sheet for a can. 2. The plated steel sheet for DI can according to claim 1, wherein the Sn content in the intermediate film is 50% by weight or less.