JPS5924884B2 - Temper rolling method for tinplate blanks - Google Patents

Description

[Detailed description of the invention] The present invention relates to a temper rolling method for tin plate blanks.

Tin plated steel sheets are widely used for food and drink filling containers, oil cans, etc., but these tin plated steel sheets are made by applying recrystallization annealing to cold-rolled cooling plates with a fibrous structure, temper rolling, and then tin plating. It is manufactured by applying.

Temper rolling of tinplate blanks does not use rolling oil.

When rolling oil is used, the coefficient of friction between the rolls and the tin plate blank decreases, the elongation rate increases, and skin pass rolling with the desired rolling reduction rate cannot be performed.

Therefore, since completely dry rolling is performed without using rolling oil, the friction coefficient is significantly higher than that in wet rolling.

Furthermore, since tinplate products have a plate thickness of 0.18 to 0.50 mm, when rolled with ordinary scratch rolls or bride rolls, they are extremely difficult to elongate and the shape straightening force is extremely weak.

For this reason, a temper rolling mill with two or more stands is generally used.
In addition, a temper rolling method using dull rolls is used in the front stand.

It is believed that when dull rolls are used in the front stand, the surface of the plate is made uneven in the front stage, and these uneven parts are crushed by the rolls in the final stand, thereby ensuring elongation and increasing the shape correction force.

Increasing the surface roughness of this dull roll further improves the elongation rate and shape straightening force, but if the surface roughness of the dull roll is further increased, the dull profile imparted to the steel sheet will be completely crushed by the scratches or bride rolls of the final stand. There was a problem in that the surface defects called dot residues occurred, which caused poor solderability and poor appearance during can manufacturing of tinplate products.

The inventors of the present invention have conducted many experiments with the aim of solving this problem.As a result, the inventors have found that if the surface profile of the dull roll for the front stand is defined within a certain range, the occurrence of dull marks can be reduced. It was discovered that it became possible to increase the roughness of the steel, and that it was possible to perform temper rolling with a high shape straightening force.

The gist of this is to use dull rolls with a roll surface roughness of 1.8 to 3.0μRa, a cutoff level of 1.2 to 1.3μ, and a PPI of 200 or more for all pre-stage stands except the final stand, and use scratch rolls or bride rolls for the final stand. This is a temper rolling method using rolls.

The reason for limiting the numerical values of the present invention as described above will be explained in detail below.

Molten steel refined in ordinary melting furnaces such as converters and electric furnaces is ingot-formed and
Steel billets are produced by blooming or continuous casting, and then hot-rolled, cold-rolled, and annealed to produce tin plates.

Steel sheets after annealing have extremely poor workability, poor shape, and extremely poor surface appearance. To solve these problems, skin pass rolling is carried out using a temper rolling mill with two or more stands arranged in a Kundem arrangement. After that, tin plating is applied.

In order to significantly improve the shape straightening force in this temper rolling, the roll surface roughness of 1.8 to 3.
It is necessary to use a dull roll with a cutoff level of 1.2 to 1.3μ and a cup PPI of 200 or more.

The unit Ra of roll surface roughness is center line average roughness of 1.8μ
If the roughness is less than that, the shape correction force becomes weak.

In addition, if the roughness exceeds 3.0μ, the dull profile on the surface of the steel sheet will not be completely crushed in the final stand, resulting in residual dull spots.

The cut-off level is a peak-cut of the peak of each mountain that determines the roughness based on a certain height.
) If it is less than 1.2μ, there is a concern that not only one mountain but also the undulations of the reference line will be counted.
If it exceeds 3μ, it will cause miscounting of small peaks, making it impossible to accurately grasp the surface condition, and the correlation with the occurrence of dull spots* will become unclear.

Furthermore, PPI is the number of peaks per inch (Peaks p
If the PPI is less than 200, the cross-sectional area of each peak becomes large, making it difficult to crush at the final stand, resulting in the formation of dull spots.

Then, depending on the roughness of the tin plate required for the final stand, a bride roll with a mirror-like surface or a scratch roll with the grinding marks left on the surface is used.

The dull roll according to the present invention as described above is made by the electric discharge dulling method or the shot blasting method using a specially selected grid, but it is also possible to make it by the skin-pass rolling method using such a roll in the front stand of a skin-pass rolling mill. The produced tinplate products do not have any residual dullness, and the shape of the steel plate is significantly better than that of conventional tinplate products.

Next, examples of the present invention will be described.

The original tinplate plate is melted in a converter and manufactured through the normal tinplate manufacturing process, and then rolled in a two-stand temper rolling mill using various dull rolls on the front stand, and a bride roll on the final stand. We investigated the occurrence of dull spots and the shape of the steel plate when

The results are shown in Table 1. As is clear from Table 1, samples Nos. 2 to 4 according to the present invention are superior to conventional materials Nos. 6 to 7 in terms of both the shape of the steel plate and the suppression of the formation of dull spots.

[Brief explanation of the drawing]

The figure is a chart showing the influence of a PPI of around 200 on the shape of a steel sheet with respect to dull roll surface roughness.

Claims (1)

[Scope of Claims] 1. In a temper rolling mill for tinplate blanks with two or more stands that does not use rolling oil, the roll surface roughness is 1.8 to 3.0 μRa on the front stand except the last stand. Cut-off level 1.2-1.3μ PP■200
A method for temper-rolling tin plate blanks, which is characterized by using the dull rolls described above and temper-rolling using scratch rolls or bride rolls at the final stand.