JPS5917199B2 - Can manufacturing method - Google Patents

Description

[Detailed Description of the Invention] The present invention is a seamless can, that is, a so-called D1 double can, by drawing and ironing electroplated tin.
The purpose is to prevent the surface defects of cans that are likely to occur during high-speed ironing process. However, recently, Dl cans made from tin cans have been attracting attention from an economic standpoint.

As the material for conventional tin Dl cans, no-reflow tin without an alloy layer is exclusively used. The reason is that no-reflow tin has a porous tin layer that absorbs lubricating oil better than regular reflow tin that undergoes tin-melting treatment after electric tin plating. -Tin alloy O gold layer (normal composition is said to be FeSn2).

), and the tin layer has excellent lubrication performance, which is said to have the advantage of reducing the ironing load in the ironing process. It is called can speed.

) is normally about 120 cans per minute, and high-speed can manufacturing exceeding 150 cans per minute has not yet been put to practical use. There are various possible causes for this, but one of the most important causes is that the faster the can manufacturing speed increases, the more surface flaws are likely to occur on the can, and the commercial value of the can will be lost. The inventor of the present application discovered the following phenomenon after various studies on conditions for solving these problems and making high-speed ironing of tinplate possible.

51) Since the required ironing load becomes smaller as the can making speed increases, there is less need to consider the lubricating properties of the tin layer.

2) The reason why surface flaws are more likely to occur as the can making speed increases is related to the transfer of the tin base iron to the ironing die. It decreases due to the presence of iron-tin alloy.

In other words, at conventional can manufacturing speeds of around 120 cans per minute, no-reflow tinting without alloys has the advantage of fewer problems with surface flaws and a lower ironing load. When the can speed exceeds approximately 150 cans per minute, in the case of unalloyed reflow, the steel will shift to ironing dies, and the scorching will become severe, resulting in the occurrence of surface flaws on the cans. This becomes significant, making high-speed Dl can production extremely difficult.

The present invention is based on the above recognition, and by using an electroplated tin that has an iron-tin alloy between the tin layer and the base metal, it is possible to solve the problems that were previously considered extremely difficult. minute 1
This invention relates to a technology that enables the production of Dl cans with virtually no surface defects at a high speed of 50 cans or more.

The features of the present invention will be explained below.

Electroplated tin alloy (FeS) is used as the can material.
The amount of n2) exceeds 0.29/Rrl as the amount of tin,
It is necessary that it be within the range of 0.61/Rrl or less.

The reason for this is that if it is less than 0.29/i, the effect of preventing surface flaws during high-speed roughening will be lost;
69/Ti! This is because if the amount is more than '', the hard iron-tin alloy will adversely affect the surface and cause severe surface flaws. The iron-tin alloy can be formed by melting the tin after electric tin plating using a conventional method, or by heating the tin layer for a short time at a temperature lower than the melting point of tin after electric tin plating, so that the tin layer remains in a non-reflow state. There are two methods: forming an iron-tin alloy on the steel sheet surface electrochemically, and then electroplating using a conventional method.
No matter what method is adopted, the effects of the present invention will not be lost.

Therefore, the tin layer may be in a reflow state or a no-reflow state. However, if the total amount of tin is too small, the lubricating effect of tin will be lost and breakage will easily occur, so it is necessary that the amount of tin be at least 1.19/m.

Further, since it is not economical to have an unnecessarily large amount of tin, it is generally preferable that the amount of tin be 5.69/TI or less, but this does not preclude the use of more than this amount. Furthermore, this does not preclude chemical treatment and oil coating on the tin layer by conventional methods. The effects of the present invention will be explained below with reference to Examples.

Two types of samples were prepared by the following method. (sample
1) Plate thickness 0.32m7! L. 5 cold-rolled steel sheets with hardness T-3
% caustic soda aqueous solution, washed with water, further immersed in 3% sulfuric acid aqueous solution, washed with water, and then
Valent tin ion 309/l, sulfuric acid 209/l, additive 59
Acidic electric tin plating was carried out at a current density of 25 A/d in an electrolytic solution containing 2.0 A/l, and the total amount of tin on both sides was reduced to 2.8 A/l.
9/m'' and then subjected to tin melting treatment to form an iron-tin alloy layer with a tin content of 0.349/TI.

(Sample 2) Using the same original plate as Sample 1, electric tinting was performed under the same conditions.

However, no heat treatment was performed after that. Each sample prepared as described above was punched into a disc with a diameter of 125.5 mm, and deep drawn using a punch with a diameter of 67.9 mm to form a cup.

Furthermore, using a punch with a diameter of 52.7 mm, the gap between the die and the punch was 0.29 m in the first stage and 0.18 m in the second stage.
The thickness of the third step was set to 0.10 mm, and three steps of continuous ironing were performed.

The can making speed is 120 cans, 150 cans, 180 cans and 2 cans per minute.
There were 10 cans in four types, and the ironing device used was a machine that is suitable for high-speed can making and is disclosed in Japanese Patent Application Laid-open No. 134484/1984 and is characterized by a punch and die that move in opposite directions.

The ironing workability was evaluated by measuring the innermost punch load during ironing. In addition, surface flaws on the processed cans were evaluated by visual observation. The results are shown in Table 1. Does not occur.

However, Sample 2, which does not contain an alloy, has significant surface flaws and is not a satisfactory product. In addition, the maximum punch load when the reflow tinplate of sample 1 is operated at 180 cans per minute is about the same as that of the conventionally used sample 2 (no-reflow tinplate without alloy) when the punching rate is 120 cans per minute. It can be seen that there is no problem from the ironing load. As described above, the present invention enables high-speed manufacturing of tin Dl cans, which has been considered extremely difficult in the past.

Claims (1)

[Claims] 1 The amount of tin exceeds 0.2g/m^2 and 0.6g/m^2
An iron-tin alloy with a composition of FeSn_2 containing less than A method for producing seamless cans characterized by ironing at a speed of .