JPS63119925A - Cold tandem rolling method for grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To prevent the wear of the rolling roll of a cold roll stand thereafter by removing a scale with a high pressure water jet and a brush after making a scale easy to peel with further cold rolling of the cold rolled grain oriented silicon steel sheet having an oxidized scale layer on the surface after its annealing treatment. CONSTITUTION:The grain oriented silicon steel sheet containing about 3wt.% Si is softened with its intermediate annealing after performing a hot rolling and pickling treatment and subjected to a cold rolling with a cold tandem rolling mill. In this case, the silicon steel plate 1 to which the oxidized scale with a thin SiO2 in 1-3mum as the main component is adhered on the surface by the intermediate annealing is subjected to a cold rolling at the rolling reduc tion rate of <=30% at a 1st stand, a split is caused on the oxidized scale layer of the steel plate surface and the state of peeling off the scale easily is made. Then, by removing the oxidized scale completely with the grinding sweep by a rotary brush 10 of a wire, etc. and the jet of a high pressure water by a nozzle 11, the rolling rolls at the cold rolling stands 4, 5, 6 thereafter being abraded by the oxidized scale is prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for cold tandem rolling of unidirectional silicon steel sheets, and in particular to rolling roll wear in cold tandem rolling of unidirectional silicon steel sheets. The present invention relates to a rolling method suitable for reducing.

<Conventional technology> Conventionally, unidirectional silicon steel sheets containing approximately 3% Si are
Usually 3. A hot-rolled steel plate with a thickness of about Qm is cold rolled to a thickness of about 0.3 mm, and then subjected to various annealing processes to be made into products and used for transformer cores, etc. Such a unidirectional silicon steel sheet is required to have excellent electromagnetic properties, that is, to have high magnetic flux density and low core loss such as eddy current loss.

In cold rolling, since the deformation resistance of a silicon steel plate is large, the pickled hot-rolled mother plate is first rolled to an intermediate thickness of about 1.0 m, then annealed and softened, and cold rolled again for 8 hours. Make the desired board thickness. Cold rolling mills usually have small roll diameters (approximately 80 to
A Sendzimir rolling mill (100 mmφ) is used and reverse rolling is performed.

<Problems to be solved by the invention> In recent years, in order to improve productivity, improve quality/yield, and save labor, there is a trend toward rolling such difficult-to-roll materials using tandem rolling mills. requires solving various problems.

One of the major problems is that the rolling rolls 11 are significantly worn, which increases the frequency of roll replacement, which impedes productivity improvement. Especially in the second cold rolling,
In Sendzimir rolling, where there is a marked tendency for wear, the rolling rolls can be replaced relatively easily, so the scale is rolled with adhesion, and if necessary, it is cleaned off with a brush or the like in the next process. In a tandem rolling mill, it takes time to change the rolls, and if the frequency increases, the effect of using the tandem rolling mill will be significantly reduced, and the roll consumption rate will also deteriorate.

In this way, the reason why rolling rolls wear out so much is that their deformation resistance is greater than that of ordinary steel, and especially during the second rolling.
During intermediate annealing, a thin scale of about 1 to 3 μm is generated on the surface, but it is still rolled. For the former, we strengthen rolling lubrication, lower the friction coefficient,
The usual measures to reduce the rolling load can be considered, and for the latter, pickling after annealing can be considered, but this is not preferable because it increases the cost due to the installation of pickling equipment and the increase in steps.

The present invention has been made in view of the above circumstances, and provides a rolling method suitable for reducing wear of rolling rolls when rolling unidirectional silicon steel sheets with a cold tandem rolling mill. The purpose is to

<Means for Solving the Problems> In the cold tandem rolling of a unidirectional silicon steel sheet, the present invention rolls the silicon steel sheet with a scale layer still attached to the intermediately annealed surface into a cold tandem rolling machine. By rolling while descaling using a descaling device installed in the line, wear of the rolling rolls is reduced. Also, in cold tandem rolling of unidirectional silicon steel sheets, intermediate annealing is performed. After rolling the silicon steel sheet with the scale layer still attached to the surface of the cold tandem rolling mill at a reduction rate of 30% or less in the first stand of a cold tandem rolling mill, By rolling while descaling using a rotating brush and/or a high-pressure water injection device, wear on the rolling rolls of the subsequent stand is reduced.

Note that the pressure of the high-pressure water injection device is 3 to 20 kgf/a.
It should be J.

Effect> The present inventor closely observed the properties of the scale layer generated on the surface of a silicon steel sheet during intermediate annealing, and
Focusing on the fact that the thickness of the rolling roll is quite thin, approximately 3 μm or less, it is possible to reduce the wear of the rolling rolls by adding a relatively simple device to perform descaling at the beginning of cold tandem rolling. They discovered that this could be done, and based on that knowledge, they completed the present invention.

Intermediate annealing of unidirectional silicon steel sheets serves both to adjust the material quality and to soften it, and since annealing is performed in an oxidizing atmosphere, a thin scale layer is formed and adhered to the surface of the steel sheet after intermediate annealing. The main component of the scale produced is silicon dioxide (S
This is considered to be very hard and act on the rolling roll like an abrasive grain, abrading the surface of the roll and causing wear.

The scale layer is thin, about 1 to 3 μmm, and is difficult to stretch compared to the base steel, so by applying pressure to reduce the thickness in the first stand of the tandem rolling mill, it is easily crushed and separated. According to experiments, at a rolling reduction rate of 2 to 3%, a crank perpendicular to the rolling direction occurs in the scale layer, which is crushed by the rolling force and easily falls off, due to the action of relative slip between the steel plate and the rolling rolls. It will peel off. Therefore, after this, the scale is peeled off and removed by using abrasive means such as a brush or by spraying high-pressure liquid such as water, hot water, or emulsion of rolling oil. It was discovered that wear can be significantly reduced.

Here, if the rolling reduction ratio of the first stand is increased, the degree of reduction becomes significant, and the crushed grains are pushed into the base iron and do not fall off easily. The rolling reduction rate at this limit is about 30%.

In addition, the scale can be removed by rolling, which breaks it up and makes it easy to remove, so a relatively simple device is sufficient.
You can clean the front and back surfaces by rotating a wire brush, nylon brush, or nylon brush containing abrasive grains, or you can spray high-pressure water. As the high-pressure water, use roll coolant. It is convenient and
It was found that the pressure required is 3 kgf/ci or more when used in combination with a polishing device, and 20 kgf/ci when used alone.

If the crushed scale is removed by rolling in this manner before being bitten into the next second stand, polishing and wear of the rolls due to scale particles will be almost eliminated in subsequent rolling.

<Example> Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 shows the main parts of the configuration of a four-stan cold tandem rolling mill. Only the work rolls 3, 4, 5, and 6 are shown, and the bank-up rolls are omitted. The silicon steel sheet 1 after intermediate annealing is supplied to a cold tandem rolling mill from a payoff reel 2, is successively reduced in thickness by a pair of upper and lower work rolls 3, 4, and 5° 6 of each stand, and is then rolled by a take-up reel 7. be wound up. Here, 8. -9 is a deflector roll.

Therefore, between the rolling roll 3 of the first stand and the rolling roll 4 of the second stand, a rotating brush 1o and a high-pressure water injection nozzle 11 are installed vertically with the steel plate l in between so as to cover the entire width of the plate. The brush 4 contacts the front and back surfaces of the rolled steel plate 1 on the exit side of the first stand and simultaneously polishes the front and back surfaces to remove one layer of attached scale. Examples of the brush include a wire brush, nylon brush,
A nylon brush containing abrasive grains or the like may be used.Alternatively, high-pressure water is jetted from the high-pressure water nozzle 5 to wash away and remove scale remaining on the batten 1.

The high-pressure water is supplied from a roll coolant pipe 15 connected to a roll coolant supply pump 14 at a raised pressure by a booster pump 12 . When low-pressure water that does not require pressure boosting is sufficient, the boost pump 12 is not necessary and the roll coolant pipe 1 is directly connected.
Note that the roll coolant is supplied to the rolls of each stand through piping 16 to 19, and after cooling each roll and steel plate and lubricating the steel plate during rolling, the roll coolant is supplied to a collector (not shown). After passing through the collection and foreign matter removal device, the coolant passes through the return pipe 20 and is returned to the coolant supply tank 13 for resupply.

Below, a general example of the descaling device according to the present invention will be explained.

A unidirectional silicon steel plate with a thickness of 1.2 mm and a width of 1000 nm is
．． It was rolled to 32 fl at a rolling speed of 800 spm.

The reduction distribution of the four stands is equal to the pressure distribution of the beam, and the reduction rate of the first stand is 28%.The zero-rotation brush lO uses one wire brush on the upper and lower surfaces, and the high-pressure water injection nozzle 11 uses pressure The test was carried out by changing it into two stages: 3gf/aj and 18kgf/cj. The effects of scale removal by these methods were investigated using the rolling length of the work rolls in the 2.3.4 stand, that is, the product length equivalent value from the time of roll change to the next change.

The decision to change the rolls should be based on surface flaws on the rolls, changes in profile due to wear (defective sheet shape), rolling instability due to roll surface roughness wear (slip, chattering, etc.)
However, the comparison was made with wear to and 2n set at 100 yen.

The results are shown in Table 1.

Table 1 As is clear from Table 1, compared to the comparative example of case 1 in which scale was not removed, the inventive examples in which scale was removed using a descaling device improved the rolling elongation and were the most In good case 5, the improvement is 1.7x in the second stand, 1.5x in the third stand, and 1x in the fourth stand.
．． It is 4 times as large, which shows that the upstream stand has a large effect.

<Effects of the Invention> As explained above, according to the Zero invention, during cold tandem rolling of a unidirectional silicon steel sheet, the silicon steel sheet with the scale layer still attached to the intermediate annealed surface is cooled. Since rolling is carried out while descaling using a descaling device installed in the tandem rolling mill line, wear on the rolling rolls of each stand can be reduced, and the length that can be rolled can therefore be increased. The time required for rolling & living can be extended, improving production efficiency.
Moreover, it is possible to improve the roll consumption rate. In particular, the rolling efficiency is approximately 84 t/h in case 1 of the example, whereas when case 5 is applied, the rolling efficiency is approximately 8 t/h per core.
and improve dramatically.

In addition, there is no need for large-scale descaling equipment such as pickling before normal rolling, and a relatively simple descaling equipment is sufficient, which has the effect of suppressing equipment investment and reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. l...unidirectional silicon steel plate, 3,4.5.6...
・Rolling roll, lO...rotating brush, 11...
High pressure water injection nozzle patent applicant Kawasaki Steel Corporation Figure 1

Claims (3)

[Claims] (1) In cold tandem rolling of unidirectional silicon steel sheets, the silicon steel sheets with scale layers still attached to the intermediately annealed surface are processed using a descaling device installed in the cold tandem rolling mill line. 1. A cold tandem rolling method for unidirectional silicon steel sheets, characterized by rolling the unidirectional silicon steel sheets while descaling them. (2) In cold tandem rolling of unidirectional silicon steel sheets, the silicon steel sheets with the scale layer still attached to the intermediately annealed surface are rolled at a reduction rate of 30% or less in the first stand of the cold tandem rolling mill. Cooling of a unidirectional silicon steel sheet, characterized in that after rolling, rolling is performed while descaling using a rotating brush and/or a high-pressure water injection device provided between the first stand and the second stand. Inter-tandem rolling method. (3) The pressure of the high pressure water injection device is 3 to 20 kgf/c
A cold tandem rolling method for a unidirectional silicon steel sheet according to claim 2, characterized in that the rolling thickness is m^2.