JPS5947608B2 - Temper rolling roll of plated steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temper rolling roll of a plated steel plate plated with zinc, tin, etc. by hot-dip plating or electroplating.

In-line temper rolling mills for plating perform rolling with low pressure in order to obtain the user-specified surface roughness and surface smoothness of plated products, and generally employ a double single-stand rolling method.

The temper rolling rolls used in this mill are generally shot-blasted dull rolls because the surface of plated products is specified to have a dull finish. However, the surface characteristics of the dull roll surface processed by shotplast have a cutoff level of 1.20 when the roughness is 2.5 to 5.0μRα.
~1.30μ and PPI less than 150, and had the following difficulties when used for temper rolling of plated finished products.

In general, if the PPI of the roll surface roughness is low, the roll surface profile will be uneven, so when temper rolling plated products, compounds of zinc/aluminum and iron, or zinc/aluminum oxide (generally Dross (called dross) seizes heavily on the roll surface, and this dross buildup not only prevents the rolled plated steel sheet from achieving the desired surface roughness, but also adversely affects surface smoothness and appearance. It's coming.

For this reason, at present, it is necessary to frequently change the rolls, which causes a decrease in work efficiency and a worsening of the roll consumption rate. The causes of dross clinging to the temper rolling roll are estimated as follows. In other words, since the profile of the dull roll surface is uneven, the plated surface layer undergoes uneven processing during temper rolling and adheres to the roll surface, causing local heat generation and microscopically changing the dull surface. It is thought that it forms an alloy with the oxide or is wrapped around the roll surface as an oxide.

If a mechanical method such as a plan roll is used to remove the dross attached to the surface of the rolling roll,
Since the relevant part forms an alloy state with the temper rolling roll,
This will damage the roll surface, and if temper rolling is performed in this state, a scratch pattern will be printed on the surface of the plated steel sheet to be rolled, which will significantly impair the surface appearance.

The inventors of the present invention have conducted many experiments aimed at solving these problems, and have found that if the die roll surface profile is defined within a certain range, dross wrap-up can be significantly reduced and the roll life can be extended. I discovered something.

The gist is that the die roll surface roughness is 2.5 to 5.0μ, the cutoff level is 1.20 to 1.30μ, and the PPI is 150.
This is a temper rolling roll having the above surface roughness.

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

The roll surface roughness unit is a, which is the center line average roughness, and if it is less than 2.5 μm, the dull profile will not be sufficiently transferred to the plated steel plate and will become close to a bright surface, resulting in a significantly shortened roll life.

Moreover, if it exceeds 5.0P, the surface roughness of the plated steel plate becomes rough and the surface appearance deteriorates. The cut-off level is the peak of each peak that determines the roughness is cut based on a certain height standard.If it is less than 1.2μ, the undulations of the reference part are counted, and if it exceeds 1.3μ, the effect is reduced. Unreasonably undercounting the number of mountains that result. That is, cutoff level 1.
2 to 1.3 μ is within the range in which the number of peaks that bring about an effect can be accurately counted.

Furthermore, PPI is the number of peaks per inch.
When this value becomes smaller, the cross-sectional area of one mountain becomes larger, the roll surface wear becomes uneven, and dross winding increases.

That is, by setting a high PPI as a dull roll surface characteristic and making the D surface profile as uniform as possible, the wear condition is also uniform and the aim is to reduce dross rolling up.

The dull roll according to the present invention as described above is made by the electric discharge dulling method or the shot plast method using a specially selected grid, but when such a roll is used as a temper rolling roll for hot-dip galvanized steel sheets or electroplated steel sheets, Significantly extends roll life by reducing dross rolling and zinc rolling.

Next, hot-dip galvanized steel sheets of sample numbers 4, 6, and 7 were temper-rolled using the temper rolling roll of the present invention, and sample numbers 1, 2, 3, 5, and 8 were subjected to in-line temper rolling on the galvanizing line using conventional dull rolls. As a result of conducting rolling using the present invention and various conventional dull rolls as mill rolls, and investigating the occurrence of dross rolling and the life of the rolls, the differences between the present invention and the conventional ones are clear as shown in Table 1. It became.

Sample numbers 4, 6, and 7 according to the present invention are the conventional 12358
It is superior in terms of dross roll-up, roll life, and surface appearance.

Note that the occurrence of dross rolling and the surface appearance are determined by visual inspection of the appearance. Surface appearance 〇: No dross (scratches) observed at all.

Galvanized steel sheets manufactured by the electroplating method were subjected to temper rolling using various dull rolls, and the zinc rolling status, roll life, and surface appearance of the rolls were investigated. The results of that investigation are shown in Table 2. According to the temper rolling method of tan rolls of the present invention, Samples Nos. 10 and 12 have less zinc rolling, have a longer roll life, and have a beautiful surface appearance than Comparative Samples Nos. 9 and 13.

Incidentally, the occurrence of zinc roll-up is determined by the determination of scratches on the galvanized steel sheet, and the surface appearance is determined by visual inspection of the appearance as follows. Surface appearance judgment criteria ○: Good appearance with no dents Δ: Slightly poor appearance with some dents visible

Claims (1)

[Claims] 1. A temper rolling roll for a plated steel sheet, characterized by having a roll surface roughness of 2.5 to 5.0 μRα, a cutoff level of 1.20 to 1.30 μ, and a PPI of 150 or more.