JP2752840B2 - Non-oriented electrical steel sheet with excellent transportability - Google Patents

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 core material such as a motor and a transformer, and more particularly to an improvement in its transportability.

[0002]

[Prior Art] Non-oriented electrical steel sheets are specified in JIS (C 25
52, 2554), which covers a wide range from the S60 class to the S9 class. These have different component composition ranges, especially Si contents, depending on the class.
The amount is nearly zero, while S9 is about 3%. In addition, Al, Mn, S, C, etc. are slightly different depending on the grade. In order to manufacture such a steel sheet, first, after being melted to a predetermined component composition, it is made into a slab by continuous casting, and then hot-rolled into a hot-rolled coil, and then subjected to one or two cold rolling operations including intermediate annealing. The product is thickened and then annealed in a continuous annealing furnace to obtain a product having predetermined magnetic properties. Here, the predetermined magnetic characteristics can be obtained by performing annealing under certain conditions. For example, a class having a large iron loss, such as S60, preferably has a low temperature of about 700 to 800 ° C. and is soaked for about 10 to 60 seconds.
In the class with low iron loss, such as 1000 ° C, high temperature as 60 to 180 seconds and long time annealing are required.

[0003] The magnetic properties, particularly iron loss properties, of electrical steel sheets depend on the crystal grain size, and the purpose of annealing is to grow the crystal grains beyond a certain size. It is economically preferable that crystal growth occurs faster at lower temperatures. The growth of crystal grains is due to impurities such as C, N, O in steel and MnS, Al
It is said that the smaller the amount of precipitation inclusions such as N and TiN, the higher the speed. Therefore, measures have been taken to minimize the impurities contained in such steel during melting or solidification.

It is known that iron loss is affected not only by impurities in steel but also by the surface roughness of steel sheet. For example, JP-A-56-13485 discloses that The steel plate is subjected to surface treatment by pickling or mirror polishing, and the average roughness Ra
Is less than 0.4 μm, the formation of an oxide layer at the time of final annealing is suppressed, and the formation of fine crystal grains on the surface, thereby improving iron loss, is disclosed in
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 are disclosed in which the formation of inclusions is suppressed by reducing the like and the like, and the core loss is improved by not forming fine crystal grains on the surface.

[0005] Furthermore, for an electromagnetic steel sheet provided with an insulating film containing an organic resin, after punching, lamination is performed and the end face is formed.
When TIG welding is performed, there is a problem that organic matter in the insulating film is thermally decomposed to generate gas, and a blow hole is easily generated in a weld bead.

As a solution to the above problem, for example,
In Japanese Patent Application Laid-Open No. 49-6744, the surface of the base is set to 20 hr.ms μinch (Ra
A method of forming an insulating film containing an organic resin after finishing to a surface roughness of about 0.5 μm or more when converted to a method has been proposed.
0.1 to 0.5 μm), which is a method of increasing the surface roughness, resulting in a decrease in the space factor. As a method to simultaneously satisfy the weldability and space factor, the base surface must be Ra: less than 0.5 μm,
And R _max : less than 2 μm (JP-A-1-289103)
Publication).

[0007]

In recent years, automation of non-oriented electrical steel sheet users, for example, motor manufacturing factories, has become more and more automatic, and vacuum steel pads have been used to convey and transport such steel sheets. Due to poor adhesion between the steel plate and the vacuum pad, there was a problem that the steel plate dropped during transportation. The present invention advantageously solves the above-mentioned problems, and aims to further improve the transportability of non-oriented electrical steel sheets of Ra <0.4 μm or less, which are desirable from the viewpoint of iron loss and space factor. It is assumed that.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and have found that the surface roughness of a steel sheet is not three-dimensional as in the conventional case but three-dimensional. Various experiments were carried out in order to evaluate the surface roughness.
FIG. 1 shows the result of examining the relationship between the surface roughness of a steel sheet by the center surface roughness SRa and the number of sheets dropped when 1000 steel sheets are conveyed by a vacuum pad. Generally, the adhesion between the steel plate and the vacuum pad is determined by the surface roughness SRa.
Is better, but Ra <0.4 μm (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. Even with steel sheets of less than 0.5 μm), the problem of poor adhesion often occurred. Further, the steel sheet manufactured by the method disclosed in Japanese Patent Application Laid-Open No. 1-289103 was good in adhesion to a vacuum pad, but extremely poor in weldability, and always adjusted to a small roll roughness during cold rolling. It is not practical because it increases the cost.

Therefore, the inventors paid attention to the irregularities on the surface and conducted further studies. As a result, while satisfying the condition of SRa ≦ 0.5 μm, the maximum peak height Rh from the center plane was further increased by 0.5.
It has been found that control 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
A non-oriented electrical steel sheet excellent in transportability (first invention) having a center plane average roughness SRa of 0.5 μm or less and a maximum peak height Rh from the center plane of 0.5 μm ≦ Rh ≦ 2.0 μm (first invention).

Further, according to the present invention, the surface roughness of the insulating film is
A non-oriented electrical steel sheet with an insulating coating (second invention) with excellent transportability, having a center plane average roughness SRa of 0.5 μm or less and a maximum peak height Rh from the center plane of 0.5 μm ≦ Rh ≦ 2.0 μm. is there.

[0012]

In the present invention, the reason why the center plane average roughness SRa of the ground iron and the coating surface is set to 0.5 μm or less is that if it exceeds 0.5 μm, there is a problem that iron loss and space factor are essentially reduced. It is. The center surface average roughness SRa here, sampling the area S _M to the center plane from a roughness curved surface, orthogonal coordinate axes on the center plane of the extracted portion, X-axis, placing the Y-axis, perpendicular to the center plane When the surface is expressed as Z = f (X, Y) with the axis as the Z axis (positive toward the outside of the steel sheet), the following equation is used.

(Equation 1) (Unit: μm).

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

Next, FIG. 2 shows that SRa is 0.5 μm or less and
The relationship between the maximum peak height Rh from the center plane and the number of falling steel plates when 1000 steel plates are conveyed by a vacuum pad when the maximum peak height Rh is varied is shown. The experiment was
The procedure was 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 make steel plates in the range of 0.3-0.35μm, and some samples have
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) Material to be used Electromagnetic 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 bichromate 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 3cm x 28cm The number of dropped steel plates was measured when 1000 steel plates were transported by a vacuum pad. (4) Surface Roughness Measurement The surface roughness profile of 1 mm × 1 mm square was measured with a three-dimensional roughness meter to determine SRa and Rh.

As is apparent from FIG. 2, when Rh on the surface exceeds 2.0 μm regardless of the presence or absence of the coating, the adhesion of the vacuum pad is deteriorated. Limited to 2.0 μm or less. On the other hand, Rh
If the thickness 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 is set to 0.5 μm. In the case of non-oriented electrical steel sheets with an insulating coating, Rh on the coating surface is 2.0μ.
m, the Rh on the steel sheet surface is not necessarily 2.0
It need not be less than μm. This is because when the coating is applied to the surface of the steel sheet, the coating is formed thicker in the recesses of the steel sheet, so that the Rh on the coating surface is smaller than the Rh of the steel sheet. The insulating film is not particularly limited, and any conventionally known one can be used.

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

[0018]

[Example] Unrolled and coated non-oriented electrical steel sheets having various SRa and Rh surfaces were manufactured using rolls with variously adjusted surface roughness, and the adhesion test using a vacuum pad was performed. The test was performed under the following conditions. (1) Material used Electrical steel sheet S60 with a thickness of 0.5 mm (2) Insulation coating The following treatment liquids A to C are applied with a roll coater,
It was baked in a hot air stove at ℃. Note that the coating amount is
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 solution C]-100% by weight of 30% magnesium phosphate aqueous solution-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 3cm The number of dropped steel plates when 1000 steel plates sheared to a size of 28 cm square were transported by a vacuum pad was measured.

FIG. 4 shows the obtained results. As is apparent from Fig. 4, the surface roughness is SRa regardless of the presence or absence of the coating.
Particularly good transportability is obtained when the Rh is 0.5 μm or less and the Rh is 2 μm or less.

[0020]

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

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the center plane surface roughness SRa and the number of sheets dropped when 1,000 steel plates are conveyed by a vacuum pad.

[Figure 2] Maximum peak height Rh from center plane and 10 with vacuum pad
It is the graph which showed the relationship with the number of sheets dropped when 00 steel plates were conveyed.

FIG. 3 is a diagram showing a procedure for measuring a maximum mountain height Rh from a center plane.

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

Continuing from the front page (72) Inventor Hiroki Tomita 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. No address) Kawasaki Steel Corporation Mizushima Steel Works (58) Field surveyed (Int. Cl. ⁶ , DB name) H01F 1/16

Claims (2)

(57) [Claims] The roughness of the surface of the ground iron is determined by the average roughness of the center plane SRa.
Is less than 0.5μm and the maximum peak height Rh from the center plane is
Non-oriented electrical steel sheet with excellent transportability of 0.5μm ≤ Rh ≤ 2.0μm. 2. The method according to claim 1, wherein the roughness of the surface of the insulating film is a center plane average roughness.
0.5μm or less in SRa and maximum peak height R from the center plane
Non-oriented electrical steel sheet with an insulating coating with excellent transportability, where h is 0.5 μm ≤ Rh ≤ 2.0 μm.