JPH05299227A - Non-directional electromagnetic steel plate having excellent carrier capacity - Google Patents

Abstract

PURPOSE:To enhance the bond properties of the title non-directional electromagnetic steel plate for increasing the carrier capacity by a method wherein the central surface mean roughness of an underneath iron and a film surface is specified not to exceed a specific value while controlling the maximum crest level from the central surface to be within specific range. CONSTITUTION:Within the non-directional electromagnetic steel plate having excellent carrier capacity also with an insulating film, the central surface mean roughness of underneath iron surface and an insulating film surface SRa does not exceed 0.5mum while the maximum crest level Rh is specified to be 0.5mum<=RH<=2.0mum. Trough these procedures, said non-directional electromagnetic steel plate controlling Rh to be within the range of <=0.5-<=2.0mum previously satisfying the inequality of SRa <=0.5 surely attracted to a vacuum pad can be carried thereby enabling the falling down accidents in transit to be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet suitable for use as an electric iron core material such as a motor and a transformer, and particularly to improve its transportability.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are specified in JIS (C 25
52, 2554), it covers a wide range from S60 class to S9 class. The composition range of these is different depending on each class, especially the Si content.
The amount is close to zero, while S9 is about 3%. In addition, Al, Mn, S, C, etc. are slightly different depending on the grade. In order to produce such a steel sheet, first, it is melted to a predetermined composition, then it is continuously cast into a slab, then hot rolled into a hot rolled coil, and then cold rolled once or twice including intermediate annealing. The product sheet is thickened and then annealed in a continuous annealing furnace to obtain a product having predetermined magnetic characteristics. Here, the predetermined magnetic characteristics are obtained by performing annealing under constant conditions. For example, a class with a large iron loss, such as S60, is suitable for soaking at a low temperature of about 700 to 800 ° C for about 10 to 60 seconds, while S9
In the class with low iron loss such as above, annealing at a high temperature of 1000 ° C for 60 to 180 seconds and long time is required.

The magnetic properties, especially iron loss properties, of electromagnetic steel sheets depend on the grain size, and the purpose of annealing is to grow the grains to a certain size or larger. Economically, it is preferred that the crystal growth occurs faster at lower temperatures. The grain growth is caused by impurities such as C, N, and O in the steel and MnS and Al.
It is said that the smaller the amount of precipitated inclusions such as N and TiN, the higher the speed. Therefore, measures are taken to reduce impurities contained in such steel as much as possible during melting or solidification.

It is known that iron loss is affected not only by impurities in the steel but also by the surface roughness of the steel sheet. For example, Japanese Patent Laid-Open No. 56-13485 discloses a method after the cold rolling step. The steel plate is subjected to surface treatment by pickling or mirror polishing, and the average roughness Ra
Is less than 0.4 μm to suppress the formation of an oxide layer at the time of final annealing and to prevent generation of fine crystal grains on the surface, thereby improving iron loss.
No. 56-58925 discloses that the roll roughness during cold rolling is reduced and the average roughness Ra after rolling is set to less than 0.4 μm so that oxygen and nitrogen diffused into the steel in the final annealing step. And the like to suppress the generation of inclusions and prevent the generation of fine crystal grains on the surface, thereby improving the iron loss.

Further, for electromagnetic steel sheets provided with an insulating coating containing an organic resin, after punching, they are laminated and end faces are laminated.
When TIG welding is applied, there is a problem that organic substances in the insulating coating are thermally decomposed to generate gas, and blow holes are easily generated in the welding bead.

As a solution to the above problem, for example, Japanese Patent Publication Sho
In the 49-6744 publication, the surface of the base is 20 Hr.ms μinch (Ra
It has been proposed to form an insulating coating containing an organic resin after finishing to a surface roughness of 0.5 μm or more).
Since the surface roughness is larger than 0.1-0.5 μm), the space factor is lowered. As a method of satisfying both weldability and space factor at the same time, Ra: less than 0.5 μm on the base surface,
And a method in which R _{max is} less than 2 μm (JP-A-1-289103).
Issue).

[0007]

In recent years, in users of non-oriented electrical steel sheets, for example, motor manufacturing factories, automation has been frequently used to adsorb and convey thin steel sheets with a vacuum pad. Since the adhesion between the steel plate and the vacuum pad is poor, there is a problem that the steel plate falls during transportation. The present invention advantageously solves the above problems, and aims to further improve the transportability of non-oriented electrical steel sheets with Ra <0.4 μm or less, which is desirable from the viewpoint of iron loss and space factor. It is what

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the inventors have found that the surface roughness of a steel sheet is three-dimensional instead of two-dimensional surface roughness as in the conventional case. Various experiments were carried out in consideration of the evaluation of surface roughness.
FIG. 1 shows that the surface roughness of a steel sheet is evaluated by the center surface roughness SRa, and the relationship between this SRa and the number of dropped sheets when 1000 steel sheets are transported by a vacuum pad is examined. Generally, the adhesion between the steel plate and the vacuum pad depends on the surface roughness SRa.
Is preferable, but Ra <0.4 μm (SRa at SRa, which is desirable from the viewpoint of iron loss and space factor, manufactured according to JP-A-56-13485 and JP-A-56-58925. The problem of poor adhesion often occurred even for steel sheets of about 0.5 μm or less). Further, the steel sheet manufactured by the method disclosed in JP-A-1-289103 had good adhesion with the vacuum pad, but had significantly poor weldability, and the roll roughness during cold rolling was always adjusted to be small. However, this is not practical because it increases costs.

Therefore, as a result of further research, the inventors of the present invention paid attention to the uneven shape of the surface and, as a result, satisfied the condition of SRa ≦ 0.5 μm and further set the maximum peak height Rh from the center plane to 0.5.
It was found that controlling within the range of μm ≦ Rh ≦ 2.0 μm is extremely effective in achieving the intended purpose. The present invention is based on the above findings.

That is, according to the present invention, the surface roughness of the base metal is
It is a non-oriented electrical steel sheet (first invention) having excellent transportability, which has a center surface average roughness SRa of 0.5 μm or less and a maximum peak height Rh from the center surface of 0.5 μm ≤ Rh ≤ 2.0 μm.

Further, according to the present invention, the surface roughness of the insulating coating is
A non-oriented electrical steel sheet with an insulating coating (second invention) that has an average surface roughness SRa of 0.5 μm or less and a maximum peak height Rh from the central surface of 0.5 μm ≤ Rh ≤ 2.0 μm. is there.

[0012]

In the present invention, the central surface average roughness SRa of the base iron and the coating surface is set to 0.5 μm or less because there is a problem that the core loss and the space factor are essentially reduced when the average surface roughness SRa exceeds 0.5 μm. Is. Here, the center plane average roughness SRa means that the area S _M is extracted from the roughness curved surface on the center plane, the orthogonal coordinate axes, the X axis, and the Y axis are placed on the center plane of the extracted portion, and the center plane is orthogonal to the center plane. When the roughness curved surface is represented by Z = f (X, Y) with the axis being the Z axis (which takes a positive value toward the outside of the steel plate),

[Equation 1] Is the value given by (unit: μm).

The maximum mountain height Rh from the center plane is
It is the maximum value of Z = f (X, Y) of the extracted portion (unit: μm).

Next, in FIG. 2, SRa is 0.5 μm or less, and
The results of an examination of the relationship between Rh and the number of drops when 1000 sheets of steel are transported by the vacuum pad when the maximum peak height Rh from the center plane is changed are shown. The experiment is
I went as follows. That is, by adjusting the roll surface roughness, Rh is 0.5 μm or more and 4.0 μm or less, and SRa is
We made steel plates in the range of 0.3 to 0.35 μm, and for some samples,
After applying the insulating coating, the effect of Rh on the adhesion of the vacuum pad was investigated. The other experimental conditions are as follows.

(1) Materials used Magnetic steel sheet S60 having a thickness of 0.5 mm (2) Insulating coating The following treatment liquid was applied by a roll coater and baked in a hot air oven at a furnace temperature of 500 ° C.

[Table 1] [Treatment liquid] 30% calcium dichromate aqueous solution 100 parts by weight Acrylic resin emulsion (resin solid content 50%) 30 parts by weight Glycerin 10 parts by weight (3) Vacuum pad adhesion test 3 cm x 28 cm The number of dropped sheets was measured when 1000 sheets of steel sheets that had been sheared into squares were transported by a vacuum pad. (4) Surface Roughness Measurement A profile of unevenness of 1 mm × 1 mm square surface was measured with a three-dimensional roughness meter to determine SRa, Rh.

As is clear from FIG. 2, when the Rh of the surface exceeds 2.0 μm regardless of the presence or absence of the coating, the adhesion of the vacuum pad deteriorates. Therefore, the Rh of the surface (the coating surface in the case of coating) is It was limited to 2.0 μm or less. On the other hand, Rh
If it is less than 0.5 μm, the roll roughness must be adjusted frequently, which is uneconomical and the weldability is significantly deteriorated. Therefore, the lower limit of Rh was set to 0.5 μm. In the case of non-oriented electrical steel sheet with insulating coating, Rh on the coating surface is 2.0μ
Even if it is less than m, Rh on the surface of the steel plate is not always 2.0
It need not be less than μm. This is because when a coating is applied to the surface of the base steel, the coating is thickly formed in the recesses of the base steel, and the Rh on the surface of the coating is smaller than the Rh of the base steel. The insulating coating is not particularly limited, and any conventionally known insulating coating can be used.

FIG. 3 shows the procedure for measuring Rh. As shown in the figure, the maximum peak height from the center plane to the top is Rh in the chart profile of surface irregularities.

[0018]

[Examples] Using rolling rolls with variously adjusted surface roughness, non-oriented and non-oriented magnetic steel sheets with various SRa and Rh surfaces were produced, and the adhesion test using a vacuum pad was performed. It carried out on the conditions shown below. (1) Material used Electromagnetic steel sheet with a thickness of 0.5 mm S60 (2) Insulating coating Apply the following treatment liquids A to C with a roll coater to obtain about 400
It was baked in a hot air oven at ℃. Note that the coating amount is
It was set to 1.0 g / m ² (one side).

[Table 2] [Treatment liquid A] • 30% calcium dichromate solution 100 parts by weight • Acrylic-vinyl acetate resin emulsion (resin solid content 50%) 30 parts by weight • Ethylene glycol 10 parts by weight

[Table 3] [Treatment liquid B] -Epoxy resin emulsion (resin solid content 50%)

[Table 4] [Treatment liquid C] · 100% by weight aqueous solution of 30% primary magnesium phosphate · 6 parts by weight of chromic anhydride · 10 parts by weight of aluminum nitrate · 400 parts by weight of water (3) Steel plate-vacuum pad adhesion test 3 cm The number of dropped sheets was measured when 1000 sheets of steel sheets sheared to a 28 cm square were conveyed by a vacuum pad.

The results obtained are shown in FIG. As is clear from Fig. 4, the surface roughness is SRa with or without the coating.
Particularly good transportability is obtained when Rh is 0.5 μm or less and Rh is 2 μm or less.

[0020]

As described above, according to the present invention, the steel sheet can be reliably transported by the vacuum pad, and the drop accident during transportation, which has been a concern in the past, can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the center surface roughness SRa and the number of dropped sheets when 1000 sheets of steel are conveyed by a vacuum pad.

[Fig. 2] Maximum peak height Rh from the center plane and 10 with the vacuum pad
It is a graph showing the relationship with the number of drops when a 00 steel plate is conveyed.

FIG. 3 is a diagram showing a measurement procedure of a maximum mountain height Rh from a center plane.

FIG. 4 is a graph showing the relationship between SRa on the surface of a steel plate and the number of dropped sheets when 1000 steel plates are transported by a vacuum pad.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Kobayashi, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture, Technical Research Division, Kawasaki Steel Co., Ltd. No address) Kawasaki Steel Co., Ltd. Mizushima Steel Works (72) Inventor Anto Kato Mizushima Kawasaki-dori 1-chome, Kurashiki City, Okayama Prefecture (No house number) Kawasaki Steel Co., Ltd. Mizushima Steel Works

Claims (2)

[Claims] 1. The surface roughness of the ground iron is the average surface roughness SRa of the center plane.
Is 0.5 μm or less and the maximum peak height Rh from the center plane is
A non-oriented electrical steel sheet with excellent transportability of 0.5 μm ≤ Rh ≤ 2.0 μm. 2. The roughness of the surface of the insulating coating is the average roughness of the center plane.
SRa is 0.5 μm or less and the maximum peak height R from the center plane
A non-oriented electrical steel sheet with an insulating coating that has excellent transportability and h is 0.5 μm ≤ Rh ≤ 2.0 μm.