JPS63183124A - Manufacture of grain-oriented electrical steel sheet having small iron loss - Google Patents

Abstract

PURPOSE:To manufacture a grain-oriented electrical steel sheet having small iron loss and undergoing no increase in the loss at a low cost by wetting a grain-oriented electrical steel sheet subjected to finish annealing with water or an aq. soln., grooving the steel sheet with a geared roll and carrying out washing and treatment for forming an insulating film. CONSTITUTION:An electrical steel sheet subjected to finish annealing or a grain- oriented electrical steel sheet treated to form an insulating film after finish annealing is grooved with a geared roll. Immediately before or during the grooving, water or an aq. soln. is fed to wet the steel sheet. A water soluble resin such as PVA or polyvinylpyrrolidone is suitable for use as the solute in the aq. soln. By the wetting, the wear of the edges of the gears is remarkably reduced and the formation of an ununiform film due to fine powder produced during the grooving is prevented. The grooved steel sheet is washed and then conventional treatment under tension for forming an insulating film or surface retreatment is carried out. Thus, an electrical steel sheet whose small iron loss is not increased even by strain relief annealing is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a low core loss unidirectional electrical steel sheet whose magnetic properties do not deteriorate even when subjected to strain relief annealing.

[Conventional technology]

In recent years, there has been a desire to reduce the iron content of unidirectional electrical steel sheets from the perspective of energy conservation. As a method for reducing iron loss, a number of methods have already been proposed as patents and industrially implemented, in which magnetic domains are subdivided by laser irradiation. The reduction in iron loss by this method is due to the strain introduced by the laser. Therefore, although this method can be used for stacked core transformers that do not require strain relief annealing, it cannot be used for wound core transformers that require strain relief annealing.

Recently, we have solved the problem that when strain relief annealing is performed, the strain introduced into the steel sheet disappears, making it impossible to achieve low iron loss.Low iron loss unidirectional electrical steel sheet whose magnetic properties do not deteriorate even after strain relief annealing. The present applicant provided a manufacturing method in Japanese Patent Application Laid-Open No. 117218/1983.

The gist of this prior invention is as follows.

(1) Finish annealed electrical steel sheet or electrical steel sheet treated with insulation coating after finish annealing, from 45 mm perpendicular to the rolling direction.
1. A method for producing a low core loss unidirectional electrical steel sheet, which comprises forming grooves under a load of 90 to 220 kir/m'' in the range of 100° C. and then heat-treating at a temperature of 750° C. or higher.

(2) The interval is 1 to 20 seconds in the rolling direction, and the width is 10 to 30 seconds.
The method according to (1) above, in which a groove is formed with a depth of 0 μm and a depth of 5 μm or more in the base metal portion.

(3) The method of (1) above, in which the groove is formed by a dotted line or a broken line.

My father published a device for carrying out the above invention in Japanese Patent Application Laid-Open No. 61-1983.
No. 5314 and JP-A-61-106717.

By the heat treatment after groove formation in the above invention, fine recrystallized grains are generated within the crystal grains of the steel sheet and the magnetic domains are subdivided. A unidirectional electrical steel sheet exhibiting an iron content value can be obtained. In this case, after forming the grooves on the unidirectional electrical steel sheet, an insulation coating treatment is performed. That is, when forming grooves on the glass coating of a finish annealed steel sheet, after forming the grooves, the entire surface is subjected to an insulating coating treatment that applies tension. On the other hand, when forming the grooves after forming the insulating film, it is preferable to perform an insulating film treatment to repair the insulating film.

[Problem that the invention seeks to solve]

However, the surface of a unidirectional electrical steel sheet that has been finish annealed has a ceramic film mainly composed of forsterite called a glass film, and the steel sheet that has been treated with an insulation film has a phosphoric acid film on the glass film. An inorganic treatment liquid containing chromic acid-colloidal silica as a main component to impart tension is applied. When grooves are formed on the surface of a unidirectional electrical steel sheet in such a state using a gear roll, wear of the tips of the teeth of the gear roll due to these coatings becomes a major problem, and as a result, iron loss increases as the tips wear out. There was a problem that the improvement effect decreased. An example thereof is shown in plot B in FIG. 1 and plot D in FIG. The present invention aims to solve all of these problems caused by wear, as well as the problem of uneven coatings caused by broken coating particles that occur when forming grooves, and to provide a unidirectional electrical steel sheet with low iron loss at low cost. be.

[Means for solving problems]

As a means for solving the above-mentioned problems, the present invention provides a low-iron steel sheet in which grooves are formed with a gear-shaped roll in a finish annealed electrical steel sheet or a unidirectional electrical steel sheet which has been subjected to an insulation coating treatment after final annealing. In the method of manufacturing a lossless one-way external electric 1 steel plate, immediately before or during the formation of grooves on the surface of the steel plate with the gear type roll, water or an aqueous solution substance is supplied to treat the steel plate in a wet state, and then a water washing treatment is performed. It is characterized by

The present invention will be explained in detail below.

A slab containing 4% or less of Si is heated and hot-rolled to an intermediate thickness, the resulting hot-rolled sheet is pickled, heat treated at this stage if necessary, and then subjected to two rounds of intermediate annealing. Cold rolling or one round of cold rolling is carried out to obtain the final plate thickness, the obtained cold rolled plate is decarburized annealed, an annealing separator is applied, and further 2
A steel sheet with a glass film obtained through the process of manufacturing normal grain-oriented electrical steel sheets, which involves subsequent recrystallization annealing, or a coating liquid for forming an insulating film, such as a tension-imparting inorganic film, is applied to the steel sheet and baked. The average load of the stress-applied portion (the value obtained by dividing the applied stress by the stress-applied cross-sectional area on the plate surface viewed from the normal direction of the plate surface) is 90 to 220 kg/■2.
Add some processing. Since the surface of the steel sheet has a glass coating or a tension-providing insulating coating, when such processing is applied, the tooth tips of the gear-shaped rolls are significantly worn, reducing the iron loss improvement effect, so it is necessary to re-polish the rolls. It was expensive, and extending its lifespan was a major issue. Therefore, the first
The present inventors investigated various ways to reduce the wear on the tooth tips, and found that the surface of the steel plate was wetted by supplying water or an aqueous solution immediately before or during the formation of the grooves with a gear-shaped roll. By forming grooves with gear-shaped rolls,
Significantly reduces tooth tip wear. After the groove forming process, further
Subsequently, surface treatment is required, and when the glass coating material is subjected to groove forming treatment, a tension-imparting insulating coating is applied and baked. In addition, at the same time as baking, heat treatment is performed at 800° C. or higher to remove curling during final annealing. On the other hand, when a material with a tension imparting film is subjected to groove forming treatment, a surface treatment for surface repair is performed to repair the peeled part of the insulation film caused by the grooves caused by the gear-shaped roll, but both surface-treated materials However, due to the residual fine powder from the coating generated during groove formation, a uniform coating cannot be obtained, resulting in a decrease in space factor and deterioration in corrosion resistance.

Second, as described above, immediately before or during the formation of grooves on the surface of a steel sheet using a gear-shaped roll, water or an aqueous solution is supplied to the steel plate or the roll, and the gear-shaped roll is wetted. After the treatment, the aqueous solution and powder are removed by washing with water, and the surface is resurfaced to achieve a uniform film treatment.

In the present invention, since the gear roll treatment is carried out in a wet state, there is an advantage that a drying oven is not required compared to the case where a dry lubricant film is formed.

If rust is a problem, a rust-resistant agent may be added to water or an aqueous solution.

The aqueous substances used in the present invention include polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene oxide, polyoxypropylene glycol, polyacrylamide, olefin-maleic acid copolymer salt, homopolymer salt of acrylic acid or methacrylic acid, or It is one kind or a mixture of two or more kinds of these copolymer salts.

Next, since the grooves may be formed on only one side of the steel plate using a gear-shaped roll, the water or aqueous solution substance applied to the surface of the steel plate using a rubber roll, spray, etc. may be applied only on one side. Of course, water or an aqueous substance may also be supplied to the gear roll. The water and aqueous solution material used after the grooves are formed by the gear roll are removed together with the powder in the subsequent water washing and brushing process.

This simple water supply treatment significantly reduces the wear on the tooth tips of gear rolls, resulting in a sustained iron loss improvement effect.
It is possible to pass 5 to 10 times more steel sheets than with no treatment,
Furthermore, since the aqueous substance can be removed by a simple water washing process, the economic advantage is very large.

The present invention is applicable not only to the above-mentioned technology but also to
It is obvious that this technique can be applied to techniques such as No. 9433.

〔Example〕 Examples of the present invention will be described below.

(Example 1) A phosphoric acid-chromic acid-colloidal silica tension imparting insulation coating treatment liquid was applied to a high magnetic flux density unidirectional electrical steel sheet finished to a thickness of 0.23 mm by a single cold rolling process, and baked at 850°C. Flattening was done at the same time. The magnetic properties are magnetic flux density (B+.”) 1.94T, iron loss (W+?/S
. ) 0.92 W/kg. The surface of the steel plate is shower-sprayed with water immediately before gear roll processing, and before it dries, the surface is coated with a gear pitch of 5II, a gear tip face width of 50 μm, a flat tooth tip shape, and a tooth inclination relative to the rolling direction. A load of 16
After introducing strain at 0 kg/am2, water washing was performed. The groove depth at this time was 20 μm. The material of the gear type roll is 5KD.
It was IID.

Thereafter, in order to repair the surface destroyed by the formation of grooves due to strain introduction, a phosphoric acid-chromic acid-colloidal silica tension imparting insulating coating treatment solution was applied and baked at 850°C.

The coating amount was 1.5 g/m on the grooved upper surface and 0.3 g/rd on the lower surface.

Plot A in FIG. 1 shows the relationship between the amount of sheet passing and the magnetic properties after heat treatment for strain relief annealing at 850° C. for 4 hours. From this, iron tjl (W l?
/S. ) improved to 0.80 W/kg, increased from around 14,000 m through the plate, and decreased to 0.8 at 21,000 m.
It became 6W/kg. Moreover, the magnetic flux density decreased with the amount of sheet passing, and decreased to 1.87 T at 21000 m. At this point, the wear of the tooth tips of the gear type roll was 200 μm.

(Comparative Example 1) A phosphoric acid-chromic acid-colloidal silica tension imparting insulation coating treatment liquid was applied to a high magnetic flux density unidirectional electrical steel sheet finished to a thickness of 0.23 ms by a single cold rolling process, and baked at 850°C. Flattening was done at the same time. Magnetic properties include magnetic flux density (Bl.) 1.93T, iron loss (WIT/S.)
It was 0.92W/kg.

The surface has a gear pitch of 51 mm and a tooth width at the tip of the gear of 50 μm.
, @A load of 180 kg/a is applied using a gear type roll with a flat glow shape and a tooth inclination of 15 degrees from the right angle to the rolling direction.
Strain was introduced at a depth of 1.5 m''. The groove depth at this time was 18 μm. The material of the gear-shaped roll was SKD 11.

Thereafter, in order to repair the surface destroyed by the formation of grooves due to strain introduction, a phosphoric acid-chromic acid-colloidal-silica tension imparting insulating coating treatment solution was applied and baked at 850°C.

The amount of film is 1.6g/n on the top surface where grooves are formed? The weight on the lower surface was 0.3 g/rd.

Plot B in FIG. 1 shows the relationship between the amount of sheet passing and the magnetic properties after heat treatment for strain relief annealing at 850° C. for 4 hours. From this, with this gear type roll, iron loss (Wtt/so)
was improved to +r to 0.81W/, and the threading amount was 2000
It increased from around m and reached 0.90 W/kg at 3000 m. In addition, the magnetic flux density decreases with the threading amount, and
m and decreased to 1.847. At this point, the wear of the tooth tips of the gear type roll was 220 μm.

(Example 2) A 10% aqueous solution of polyethylene oxide (molecular fi 40000) was applied with a rubber roll to the surface of a glass coating material of a high magnetic flux density unidirectional electrical steel sheet finished to a thickness of 0.23 mm by a single cold rolling process. The coating amount on the upper and lower surfaces is adjusted by the depth of the groove on the rubber roll, and the coating amount is 1.0 g/rrf on the upper surface.
, the lower surface was 0.02 g/rd. Before the polyethylene oxide aqueous solution dries, the surface of the polyethylene oxide aqueous solution is coated with a gear pitch of 8 l, a gear tip tooth width of 50 μm, and a flat tooth tip shape.
Strain was introduced at a load of 180 kg/xi2 using a gear-shaped roll whose teeth were inclined at 15 degrees from the right angle to the rolling direction. The groove depth at this time was 20 μm. The material of the gear roll was SKD 11.

After introducing strain, the polyethylene oxide on the surface was removed by washing with water, and then a phosphoric acid-chromic acid-colloidal silica tension-imparting insulating coating treatment solution was applied to repair the surface destroyed by the formation of grooves due to strain introduction. Flattening was performed at the same time as baking at ℃. The amount of film is 4.0 on both the top and bottom surfaces.
It was 5g/rrr.

Plot C in FIG. 2 shows the relationship between the amount of sheet passing and the magnetic properties after heat treatment for strain relief annealing at 850° C. for 4 hours. The plot on the vertical axis corresponds to the magnetic properties after the sample was taken before the gear roll test and strain-removed annealed at 850°C for 4 hours, with a magnetic flux density (B,.) of 1.94T and iron loss (Wl ?/
+111) 0.98W/kg.

Iron loss (W+
t/so) improved to 0.81W/kg, 4000
Increases from around 0m to 0.86W/k at 60000m
I got into g. In addition, the magnetic flux density decreases with the threading amount, and 6
It decreased to 1.87T at 0000m. At this point, the wear of the tooth tips of the gear type roll was 160 μm.

(Comparative Example 2) The surface of the glass coating material of a high magnetic flux density unidirectional electrical steel sheet finished to a thickness of 0.23 m by a single cold rolling process was
Strain was introduced at a load of 180 kg/-2 using a gear-shaped roll having a tooth width of 50 μm at the tip, a flat tooth tip shape, and a tooth inclination of 15° from the right angle to the rolling direction. The groove depth at this time was 18 μm. The material of the gear roll was SKD 11.

After that, in order to repair the surface that was destroyed due to the formation of grooves due to the introduction of strain, a phosphoric acid-chromic acid-colloidal silica force-based tension imparting insulation film treatment solution was applied, and flattening was performed at the same time as baking at 850°C. .

The amount of film is 4.5g/n for both the top and bottom surfaces? Met.

Plot D in FIG. 2 shows the relationship between the amount of sheet passing and the magnetic properties after heat treatment for strain relief annealing at 850° C. for 4 hours. In addition, the plot on the vertical axis corresponds to the magnetic properties after the sample was taken before the gear roll test and strain-relieving annealing at 850°C for 4 hours. ,,,
,. )0.97W/kg.

With this gear type roll, iron loss (W It /%) is 0.
．． It improved to 81W/k, increased from around 4000m, and reached 0.87W/kg at 6000m.

In addition, the magnetic flux density decreases with the threading amount, reaching 1 at 6000 m.
．． It decreased to 86T.

At this point, the wear of the tooth tips of the gear type roll was 180 μm.

〔Effect of the invention〕

According to the present invention, in a method for processing electrical steel sheets that uses a gear roll method to obtain good quality iron even after strain relief annealing, immediately before or during the formation of grooves on the surface of the steel sheet using gear rolls. By supplying water or an aqueous solution and introducing strain in a wet state, it is possible to significantly reduce the wear of the gear cutting edge, and at the same time solve the problem of uneven coating due to coating fine powder generated during groove formation, which is economical. There are some great benefits.

[Brief explanation of the drawing]

FIGS. 1 and 2 show the results of Examples and Comparative Examples.

Claims (1)

[Scope of Claims] 1. A low core loss unidirectional electrical steel sheet in which grooves are formed with a gear-shaped roll on a finish annealed electrical steel sheet or a unidirectional electrical steel sheet treated with an insulation coating after finish annealing, and then the insulation coating is treated. In the method for manufacturing a steel plate, immediately before or during the formation of grooves on the surface of a steel plate using the gear-shaped roll, water or an aqueous solution is supplied to treat the steel plate in a wet state, and then a washing process is performed to form a normal tension-adding insulating coating. A method for producing a low iron loss grain-oriented electrical steel sheet, which comprises subjecting it to treatment or resurface treatment. 2. The dissolved substance in the aqueous solution supplied by the gear type roll immediately before or during the formation of the groove is a water-soluble resin such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, polyethylene oxide, polyoxypropylene glycol, or polyacrylamide. , an olefin-maleic acid copolymer salt, a homopolymer salt of acrylic acid or methacrylic acid, or a copolymer salt thereof, or a mixture of two or more thereof.