JPS63295005A - Mill for cold tandem rolling of silicon steel sheet - Google Patents

Abstract

PURPOSE:To improve the specific productivity of rolls and the production efficiency by installing devices giving tension and bending between a 1st stand and a rewinding reel of a tandem mill and performing rolling. CONSTITUTION:A tension leveler 15 and a grinding sweeper 18 are installed between a deflector roll 3 following a payoff reel 2 and a work rolls 11 of a 1st stand. The leveler 15 consists of a couple of bridle rolls 16, 16 and a roller leveler 17 and the sweeper 18 consists of a rotating brush 19 and high pressure water spraying nozzles 20. After intermediate annealing, a silicon steel sheet 1 having thin scale layers is descaled by the leveler 15 and scales are removed by the sweeper 18; then the sheet 1 is rolled by rolls 11-14. Thus, the number of roll changes is reduced and the specific productivity of the rolls and the production efficiency are improved because of reduction in wear of the rolls 11-14.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to cold tandem rolling equipment for silicon steel sheets.
In particular, the present invention relates to rolling equipment suitable for reducing wear of rolling rolls in cold tandem rolling of silicon steel sheets.

<Conventional technology> Conventionally, unidirectional silicon steel sheets containing approximately 3% Si are produced by cold rolling a hot rolled steel sheet approximately 3.0 m thick to a thickness of approximately 0.3 mm, and then subjecting it to various annealing methods. It is made into products and used in 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 silicon steel sheets is large, the pickled hot-rolled mother sheet is first rolled to an intermediate thickness of about 1.0 mm, then annealed and softened, and then cold rolled again to form the desired shape. The thickness of the board is as follows. Cold rolling mills usually have small roll diameters (approximately 80 to
1001φ) A Sendzimir rolling mill is used for reverse rolling.

<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 major problem is that the rolling rolls are severely worn.
This increases the frequency of roll replacement, which hinders productivity improvement. In particular, in Sendzimir rolling, where the tendency of wear is remarkable in the second cold rolling, the rolling rolls can be replaced relatively easily, so that the scale is removed and the rolling is carried out as needed in the next process. It used to be cleaned with brushes, etc., but in a tandem rolling mill it takes time to change the rolls, and if the frequency increases, the effect of using a tandem rolling mill will be significantly diminished, and the roll consumption per unit of production 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.
Although a thin scale of approximately 1 to 3 μm is generated on the surface during intermediate annealing, it is rolled as is. For the former, the usual measures to strengthen rolling lubrication, lower the friction coefficient, and reduce the rolling load can be considered, and for the latter, pickling after annealing can be considered, but installation of pickling equipment is considered. This is undesirable as it increases costs due to additional investment and process steps.

Therefore, the present applicant has already filed the patent application No. 61-2639.
As disclosed in No. 22, a silicon steel sheet with a scale layer still attached to the intermediately annealed surface is rolled in a cold tandem rolling mill line, particularly between the first stand and the second stand. We proposed a method of rolling while descaling using a scaling device.

However, when conducting experiments using the above method, it was discovered that the following problems were latent.

■ The surface of the rolling roll on the first stand becomes rough due to scale, resulting in a short lifespan and frequent roll replacement.

■Furthermore, the broken scale adheres to the roll surface and is transferred to the steel plate surface, causing surface flaws, which deteriorates the steel plate quality.

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

<Means for solving the problem> 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 rolls are quite thin, approximately 3 μm or less in thickness, the wear of the rolling rolls is reduced by adding a relatively simple device to perform descaling before starting cold tandem rolling. The present invention was completed based on this finding.

That is, the present invention provides silicon' This cold tandem rolling equipment for silicon steel sheets is characterized by having a device for applying tension and bending, and a grinding device in between.

<Function> Intermediate annealing of 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 layer of scale is formed and adhered to the surface of the steel sheet after intermediate annealing. The main component of the scale produced is silicon dioxide (SiOz
), which is extremely hard and is thought to act on the rolling roll like an abrasive grain, polishing the surface of the roll and causing wear. The scale layer is thin, about 1 to 3 μm, and is difficult to stretch compared to the base steel. Therefore, by bending and stretching the scale layer using a leveler prior to rolling, it is easily crushed and peeled off. According to experiments, the elongation strain I~3
%, cracks occur in the scale layer at right angles to the elongation direction, and the scale layer is crushed by the elongation and compressive strain generated on the front and back surfaces of the steel plate due to bending and unbending of the leveler, making it easy to fall 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 an emulsion of rolling oil.
It has been found that the wear of the rolls after the stand can be significantly reduced.

In addition, as for the method of removing scale, it can be easily removed by crushing it with a leveler, so it is relatively easy to remove it. It is convenient to use roll coolant as the high pressure water.
Pressure is 3kgf/crA or more when used in combination with a cleaning device.
Alone it was found that 20 kg f/c+fl was required.

Note that, as another method for descaling on the entry side of a tandem rolling mill, it is also possible to directly polish the scale layer, taking into account that the scale thickness is relatively thin at 1 to 3 μm. That is, for example, grindstone grinding, in which the surface of a steel plate is ground by rotating a grindstone, or belt grinding, in which abrasive grains are implanted in cloth or paper and rotated to form a band, can be used. In this case, since the scale layer is thin,
It is practical because it can reliably descale by light grinding even with relatively simple equipment, and there is relatively little wear and tear on the grindstone and belt.

As described above, by removing the scale before the steel plate is bitten by the first stand, grinding and wear of the roll due to scale particles during rolling after the first stand can be almost eliminated. In addition, if descaling is performed in the rolling line immediately before rolling, rolling can be performed immediately thereafter, so there is no need for rust prevention treatment after descaling.

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

FIG. 1 is a side view schematically showing the main parts of the configuration of a four-stand cold tandem rolling mill. Rolls 11.12.
13.14 shows only the work role and omits the backup role. A silicon steel plate (hereinafter simply referred to as a steel plate) 1 after intermediate annealing is supplied from a payoff reel 2 to a cold tandem rolling mill 1o, and is sequentially reduced in thickness by a pair of upper and lower work rolls 11, 12, 13° 14 of each stand. is,
It is wound up by a take-up reel 5. Here, 3.4 is the deflation crawl.

A tension leveler 15 and a grinding device 18 are disposed between the deflation crawler 3 after the payoff reel 2 and the first stand rolling roll 11. Here, tension leveler 1
5 is composed of a pair of priddle rolls 16, 16 that apply tension to the steel FiI, and a roller leveler 17 that is made up of a plurality of rolls that apply bending. This roller leveler 1
The roll diameter of No. 7 is small, about 50 to 80 ma+φ, and can give the steel plate 1 an elongation strain of about 1 to 3%. The scale cleaning device 18 includes a rotary brush 19 and a high-pressure water jet nozzle 20, which are arranged above and below the steel plate 1 so as to cover the entire width of the steel plate 1, either singly or in combination.

The rotating brush 19 contacts the front and back surfaces of the steel plate 1 on which the scale has been destroyed by the tension leveler 15, and simultaneously polishes the front and back surfaces to remove the thin layer of scale that has adhered.
The brush is a wire brush.

A nylon brush or a nylon brush containing abrasive grains may be used, and the high-pressure water jet nozzle 19 jets high-pressure water to wash away and remove scale remaining on the steel plate 1. The high-pressure water is supplied from a roll coolant pipe 8 connected to a roll coolant supply pump 7 at an increased pressure by a boost pump 21 . When low-pressure water that does not require pressure increase is sufficient, the boost pump 21 is not necessary and may be supplied directly from the roll coolant pipe 8. Note that the roll coolant is supplied to the rolls of each stand through the pipe 8,
After each roll and the steel plate are cooled and a part of the steel plate is rolled and lubricated, the coolant is returned to the coolant supply tank 6 through a return pipe via a collection and foreign matter removal device (not shown) and is resupplied.

Incidentally, as the polishing device 18, a belt sander may be used instead of the rotating brush 19 to obtain the same effect.

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

0.3 silicon steel plate with plate thickness 1.2ma+ and width 1000m
2III11 at a rolling speed of 800 mpm. The pressure distribution of the four stands was equal pressure distribution on the beam.

The tension roller 15 has a roll diameter of 50 mm + φ, a tension of about 5 kgf/mm", and a bending strain of 2.4%.
The condition was set as follows.

As for the polishing device 18, comparison was made for five cases shown in Table 1.

As a result of scale removal by these, the first
The rolling extension of the whirl roll of the front stand and the 4th stand,
That is, Table 2 shows the results obtained by converting the product length from the time after the roll change to the next roll change.

The decision to change the rolls should be based on roll surface flaws, profile changes due to wear (temporary shape defects), rolling instability due to roll surface roughness wear (slip, chattering, etc.)
However, the comparison was made using a wear amount of 0.2+ms as a guide.

As is clear from Table 2, compared to the conventional example in which scale was not removed, the examples of the present invention in which scale was removed using a descaling device had the rolling lengths shown in Table 2, and were the best. In Cases 3 and 5, the improvement was 1.7 times in the first stand and 1.4 times in the fourth stand, indicating that the upstream stand has a larger effect.

It should be noted that a similar effect of increasing the rolling length has been observed for the intermediate second and third stands as well.

<Effects of the Invention> As explained above, according to the present invention, in cold tandem rolling of silicon steel sheets, the silicon steel sheets with the scale layer still attached to the intermediate annealed surface are rolled in the cold tandem rolling mill. Since rolling is performed after descaling using a descaling device installed on the entry side, it is possible to reduce wear on the rolling rolls of each stand, thereby increasing the possible rolling length and reducing roll assembly. Since it is possible to lengthen the time until replacement, it is possible to improve production efficiency and roll consumption. In particular, the rolling efficiency is approximately 84 t/h in the conventional example, whereas when Case 6 is applied, it is dramatically improved to approximately 108 t/h.

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 drawings]

FIG. 1 is a side view schematically showing an embodiment of the present invention. 1...Silicon steel plate. lO...Cold tandem rolling mill. 11, 12.13.14... Roll. 15...Tensin leveler, 16...Pride roll. 17... Roller leveler, 18... Grinding device.

Claims (1)

[Claims] In a silicon steel sheet cold tandem rolling facility comprising an unwinding reel, a multistage tandem rolling mill, and a take-up reel, the unwinding reel and the first stage of the multistage tandem rolling mill
Cold tandem rolling equipment for silicon steel sheets, characterized in that a device for applying tension and bending and a grinding device are arranged between the stand and the stand.