JPS5830932B2 - Can openability and score - manufacturing method for easy-open can steel sheets with excellent workability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a steel plate for easy-open cans that has particularly excellent can-openability pJ and score workability.

Easy-open cans, which have a score of an appropriate depth engraved on the can body or can lid in advance and can be opened without tools such as a can opener, are used for beer cans, carbonated beverage cans, juice cans, etc. It started to get worse.

This easy-open can/lid is primarily made of aluminum.

However, aluminum cannot be used in all cases due to its corrosion resistance against the contents, and recently, easy-open cans and lids using steel plates have been considered.

However, since steel is inherently tenacious, it cannot be opened as easily as aluminum, and is inferior to aluminum easy-open cans and lids.

Therefore, various studies have been made to improve the ease of opening the can.

Among these, it is known that can opening performance can be improved by making the residual thickness of the score 717 days as thin as possible, but current score processing technology or easy-open can lid manufacturing technology prevents variations in the score residual thickness. It's difficult,
In addition, since cracks are likely to occur in conventional steel plates during scoring, the remaining thickness of the score cannot be reduced.

Furthermore, if the score is processed so that the remaining thickness of the score is reduced, cracks will occur at the bottom corners of the score, resulting in a partial decrease in strength and problems such as the inability to withstand the internal pressure of the can.

For these reasons, the current situation is that no one has been able to produce aluminum Easy-O 77 cans and easy-open cans and lids that double as lids.

In view of these circumstances, the present invention was made as a result of many experiments and researches, and it is possible to obtain a score that is thinner during scoring processing, less likely to cause cracks, and a score that can be obtained when opening the can. An object of the present invention is to provide a steel plate for easy-open cans that requires only a very small force to partially cut, and has much better so-called can-opening properties than conventional cans.

And the gist of it is less than 0.02% carbon, S
i: o, t or less, Mn: 0.1 to 0.5%, oxygen: 0.01% or less, % carbon + oxygen is 0.02% or less, the balance is iron p and unavoidable impurities Cold rolled The steel plate was soaked to a recrystallization temperature of -750°C and heated to 10~100'C/s.
The present invention provides a method for producing a steel sheet for easy-open cans having excellent can-openability and score workability, which comprises continuous annealing at a cooling rate of EC, followed by skin pass rolling at a rolling reduction of 6 to 20.

The present invention will be specifically explained below.

The reason why the composition range of the steel plate for easy-open cans was determined as described above is as follows.

If carbon is contained in an amount greater than 0.02%, the strength will increase, the mouth can properties will deteriorate, and cracks will easily occur in the scored portion, so the smaller the content, the better.

Any method may be used to reduce the carbon content to less than 0.02%, such as vacuum degassing treatment of molten steel or decarburization annealing of hot rolled steel sheets.

If the silicon content is high, it will deteriorate the corrosion resistance of the can, and it will harden the steel significantly, making it difficult to open the can.
% or less.

Manganese is added as an unavoidable impurity in order to prevent the hot binding properties of steel sheets due to sulfur present in the steel, and from this point of view, the content of manganese is required to be between 0.1 and 0.5.

When the oxygen content increases, oxide inclusions increase and cause cracks to occur in the scored area.

It is necessary to keep it below 0.01%. In addition, in order to prevent cracks in the score processing area even when the remaining score thickness becomes thin, it is insufficient to individually regulate the upper limits of each content of carbon and oxygen, and the upper limit of the total amount of these peripheral components must be stipulated.

In other words, to prevent cracks from occurring in the score processing area,
The total amount of peripheral components (% carbon+oxygen) should be 0.02 or less.

The above-mentioned steel is produced by melting in an appropriate method such as a converter or electric furnace, and is made into a slab by forming into two ingots, or by continuous casting, and the slab is continuously hot-rolled at a temperature of 850°C or higher. and cold rolling at a rolling reduction of 60% or more.

In the present invention, this cold rolled steel plate is continuously annealed at a temperature higher than the recrystallization temperature.

Continuous annealing of a product with controlled carbon content and oxygen content as described above is combined with skin pass rolling to be described later, and the force required to cut the scored part is greatly reduced, greatly improving the so-called openability. .

As a condition for continuous annealing, the soaking temperature should be set to a recrystallization temperature ~750℃
In addition, sufficient riveting cannot be achieved unless the cooling rate is 10~b higher than the recrystallization temperature, and if it exceeds 750°C, the crystal grains become large, causing roughness during riveting and causing cracking during riveting.Also, cooling rate If the rate is too slow or too fast, it will be difficult to adjust the rate to a value appropriate for the hardness of the steel plate, so the lower limit is set at 10°C/see.

The upper limit was set to 100°C/see.

Continuously annealed steel sheets are skin-pass rolled at a reduction rate of 6 to 20%, and this skin-pass rolling is necessary to improve can openability. It also improves workability when riveting is performed during lid manufacturing. do.

However, if the rolling reduction ratio is less than 6%, it will not be effective in improving can openability, and if it is more than 20%, cracks may occur in the scored portion, and it will be difficult to perform riveting.

The steel sheet for cans manufactured by the above method is then subjected to surface adjustment such as de-fingering and pickling, and then tin-plated, chrome-plated, etc.
Nickel-plated, aluminium-plated, phosphate treated and other chemical conversion treatments are used as steel sheets for easy-open cans.

It can also be applied as a steel plate for the various plated buttons and easy-open cans in a single casing that is not subjected to chemical conversion treatment.

Examples of the present invention will be described below.

Example 1 Steel with the components shown in Table 1 was melted in a converter and subjected to the normal stripping process, but the finishing temperature after continuous casting was 890°C.
It was hot rolled to 2 to 3 rra under the conditions of 1°C and a winding temperature of 600°C.

After pickling, cold rolling at 0.24mmt, steel A, B button and C
For example, continuous annealing was performed at 700°C for 30 seconds at a cold gas rate of 30'C/sec, and for steel and E, box annealing was performed at 650'C for 1 hour.

These annealed coils were skin pass rolled at a rolling reduction of 12 degrees.

Next, tin plating was applied using a conventional electroplating line.

The steel sheet for cans manufactured by this process has a score of 0.0.
A 070m pull open type easy open can/lid was fabricated and the opening force was measured.

These results are shown in Table 2. The score is the critical score at which cracks occur in the machined part.
The score workability was investigated by changing the score residual thickness for the products skin-pass rolled in the second stage.

The results are shown in Table 3.

As is clear from Table 2, steels A and B manufactured by the manufacturing method of the present invention
The can opening force is small in both cases, and the can opening force of the pull-open aluminum can lid currently used (max. 3.4
K7), which shows that the can opening performance is much better.

Further, even if the steel composition is within the scope of the present invention, box annealed steel D is outside the scope of the present invention, and steel C is continuously annealed, where the steel composition is outside the scope of the present invention and the annealing conditions are within the scope of the present invention. Both have a large can opening force and are somewhat inferior to the aluminum cans and lids mentioned above.

Furthermore, in terms of steel composition and annealing conditions, the can opening force of Ano Steel E is the best among these, outside of the present invention.

Next are the measurement results of the critical score for crack generation and residual thickness.

As is clear from Table 3, steel A manufactured by the manufacturing method of the present invention
, B has a much smaller critical score residual thickness than steels C and E.

This is not the case in the past, and it means that cracks are less likely to occur due to score processing, and considering the current easy-open can/lid manufacturing technology and score processing technology, cracks will not occur even if there is some variation in the score processing. This shows that it is possible to make a lid.

Example 2 Steel A in Table 1 was hot-rolled and then cold-rolled with different cold rolling reductions, and then continuously annealed at 700°C for 30 seconds. , 12.0%, 18.0
Skin pass rolling was performed at %$- and 24.0% and 0.24
mm steel plate.

Next, tin plating was applied using a conventional electroplating line.

The steel sheet for cans manufactured by this process has a score of 0.0.
070rML pull open
We processed the mold into easy-open cans and lids, measured the can opening force, and investigated the occurrence of cracks during rivet processing.

These results are shown in Table 4.

As is clear from Table 4, the can opening force of both steels A-2 and A-3A-4U, which were skin-pass rolled at the rolling reduction of the present invention, is small and is smaller than that of the pull-open type aluminum can/lid. , and no cracking occurs during riveting.

Also, steel A-5 was skin-pass rolled at a reduction rate higher than that of the present invention.
During rivet processing, cracking occurred frequently, making it impossible to form rivets.

Steel A-1, which was skin-pass rolled at a rolling reduction lower than that of the present invention, had less cracking during riveting, but the opening force was large.

As described above, steel sheets produced by skin pass rolling at rolling reductions other than those according to the present invention are inferior to steels produced according to the present invention as steel plates for easy-open cans.

As described above, the steel sheet for easy-open cans produced according to the present invention has excellent score workability and can opening performance.

Claims (1)

[Claims] 1 Carbon less than 0.02%, Si 0.1% or less, Mn0
．． 1 to 0.5 yen, contains 0.01% or less of oxygen, and %
A cold-rolled steel plate with a carbon content + oxygen content of 0.020% or less, the remainder consisting of iron buttons and unavoidable impurities, is soaked at a temperature between the recrystallization temperature and 750°C, and then heated for 10 to 100'
A steel sheet for easy-open cans with poor openability and score workability, characterized by continuous annealing with cooling at a cooling rate of C/see, followed by skin pass rolling at a rolling reduction of 6 to 20. Manufacturing method.