BRPI0717360A2 - oriented granulation electric plate, superior in watt loss - Google Patents

Abstract

ORIENTED GRANULATION ELECTRIC SHEET, LOSS LOSS IN WATT. The present invention relates to a higher watt-loss oriented granulation electric sheet compared to the past, dividing the watt loss of the oriented granulation electric sheet by introducing laser beam firing deformation etc. loss of hysteresis and loss of eddy current, and particularly from the point of view of eddy current loss, by quantitatively controlling, appropriately, the distribution of deformation and residual stress in the direction of plate thickness, ie the electrical plate of oriented granulation, obtained by firing a laser beam, etc., to introduce deformation lines substantially perpendicular to the rolling direction, evenly, in a sheet width direction and, cyclically, in the rolling direction for domain control characterized by the fact that the two-dimensional distribution of a compressive residual stress in a lamina direction Nation, which occurs near a site of introducing deformation at a cross section perpendicular to the width direction of the plate, the value of the compressive residual stress in the rolling direction, integrated in the region of the cross section where there is compressive residual stress, is within of a predetermined range.

Description

Report of the Invention Patent for "WATT-LOSS TOP-ORIENTED GRAINING ELECTRIC SHEET".

Technical Field

The present invention relates to a watt-loss-superior oriented granulation electric plate that uses laser or similar firing to introduce residual voltage for magnetic domain control.

Background Art

An electric oriented granulation plate with an easily magnetized shaft in the rolling direction of the steel plate is mainly used for transformer iron cores etc. In recent years, there has been a strong demand to reduce the wattage of iron cores from an energy saving point of view.

The watt loss of electrical plates can be roughly divided into hysteresis loss and eddy current loss. Loss of hysteresis is known to be influenced by the orientation of crystals, defects, degree limits, etc., while loss of eddy current is influenced by plate thickness, electrical resistance, magnetic domain width, etc.

There are limits to the technique of controlling and refining the orientation of crystals in order to reduce the loss of hysteresis, so in recent years many proposals have been made in the technique of subdividing the magnetic domain width in order to reduce the eddy current loss, which is responsible for most of the watt loss, ie the magnetic domain control technique.

As a method to this end, Japanese Patent Publication (B2) No. 6-19112 describes a method of producing granulated oriented electric plate, which uses YAG laser firing to introduce voltage lines substantially perpendicular to the rolling direction cyclically in the rolling direction and thereby reduce the loss in watt. The principle behind this method, called laser magnetic domain control, is to use a laser beam to explore the surface and produce voltage, because the magnetic domain width of 180 ° is subdivided and the loss in watt is reduced.

In addition, Japanese Patent Publication (A) No. 2005-248291 presents a new proposal which observes the maximum value of the residual stress in the rolling direction formed on the surface of the steel plate.

Description of the Invention

Almost all proposals so far regarding the introduction of local stress on the steel plate surfaces and the subdivision of the magnetic domain width by 180 ° to reduce watt loss, ie laser magnetic domain control, including The first prior art patent document uses trial and error method to limit laser type, laser beam focal point format, laser energy density, laser firing pitch and others. laser trigger parameters. Proposals are extremely fragmentary and lack uniformity. The reason is that no reference is made to a quantitative description of the main factors that cause the subdivision of the magnetic domain and the reduction in watt loss, ie voltage or residual voltage. Inherently, the reduction in watt loss from laser firing, even under the same laser firing conditions, due to steel plate absorption index (determined by laser wavelength or surface properties, shape and film composition ) or film thickness, the conversion of laser energy to thermal energy (temperature distribution and temperature history) differs, so that even if the laser firing conditions are equal, the deformation introduced differs depending on the steel sheet properties. In addition, even with the same thermal energy (temperature distribution or temperature history), due to the composition of the steel plate (eg Si amount), physical property values (eg Young's modulus or limit value) differ so that the residual voltage also differs. Therefore, even if optimum laser firing conditions are achieved with respect to the steel plate under certain conditions, even a slight change in the state of the film causes the way in which deformation is introduced due to the laser to differentiate and the watt loss value changes so that laser firing conditions and watt loss reduction do not match each other on a 1 to 1 basis. Therefore, attempts have been made to find the inherent factors that influence the wattage. loss in watt. The second patent document refers quantitatively to deformation and residual stress, but there were limits to reducing watt loss only by controlling the deformation or residual tensile stress of the steel plate surface.

The object of the present invention is to provide a higher oriented wattage granulation electric plate in wattage loss compared to the step, dividing the wattage loss of the hysteresis loss and parasitic current oriented granulation electric plate, particularly from the standpoint of eddy current loss by quantitatively controlling the distribution of deformation and residual stress not only on the surface, but also within the direction of plate thickness under appropriate conditions.

The inventors performed experiments in magnetic domain control, introducing deformation and residual stress in the laser firing-oriented granulation electric plate etc. and initiated an in-depth research to investigate the residual voltage distribution introduced in the low watt loss oriented granulation electric plate. As a result, the inventors found a correlation between residual stress and eddy current loss and found that if the compressive stress value and the deformation step are controlled, it is possible to realize a higher oriented grain plate in loss in watt.

The main point of the present invention is as follows.

(a) A grain oriented electric plate obtained by firing a continuous wave laser beam to uniformly introduce a deformation in a plate width direction perpendicular to a lamination direction, cyclically in the lamination direction, and in lines substantially perpendicular to the rolling direction, characterized by the fact that in the two-dimensional distribution of a compressive residual stress in the rolling direction, which occurs close to a deformation insertion site, in a perpendicular cross section In the direction of plate width, the value of the compressive residual stress in the rolling direction, integrated in the cross-sectional region where there is a compressive residual stress, is 0.20N to 0.80N.

(2) an oriented granulation electric plate as described in said item (1), characterized in that a cyclic step in said deformation lamination direction, uniform in said plate width direction, due to heating of the laser beam is from 2 mm to 8 mm.

Brief Description of the Drawings

Figure 1 is a schematic view of an apparatus used for a method of producing an oriented granulation electric plate of the present invention.

Figure 2 shows a two-dimensional distribution of a residual stress in the rolling direction, close to the laser firing position in a cross section of the rolling direction / sheet thickness direction.

Figure 3 is a view of a relationship between a maximum value of a tensile residual stress in the rolling direction and a watt loss W1 17/50.

Figure 4 is a view of a relationship between a cumulative compressive stress value aS and a parasitic current loss We (fixed 4mm laser firing pitch).

Figure 5 is a view of a relationship between a cumulative compressive voltage aS and a loss in watt W17Z50 (Fixed 4mm firing distance).

Figure 6 is a view of a relationship between a PL laser firing step and a wattage loss W17 / 50 (diameter of laser firing in the DL rolling direction of 0.1 mm and laser firing diameter in the direction of fixed sweep lengths of 0.5 mm).

Figure 7 is a view of a relationship between a maximum value of a compressive residual stress in the rolling direction and a loss in watt W1 r / only.

Best Mode for Performing the Invention

The inventors have considered the two-dimensional distribution of residual stress in the rolling direction in the vertical cross section to the plate width direction and the laser firing step in the rolling direction for various laser firing conditions in the method of application. a laser on the surface of the oriented granulation electric plate so as to introduce deformation lines substantially vertically to the rolling direction at a constant step in the rolling direction so as to improve watt loss and conditions have been found, whereby a higher oriented grain plate can be obtained in watt loss. In this case, the "sheet width direction" is a direction perpendicular to the rolling direction. As a method of introducing deformation lines such as the above into the surface of the oriented granulation electric plate, in addition to the laser firing method, ion injection, electroplating machine working, local coating, vibration may be mentioned. ultrasonic etc. The conditions can be applied to the oriented granulation electric plate by introducing deformation by any method. Below, drawings are used to explain the laser firing oriented granulation plate of the present invention.

Figure 1 is an illustrative view of the method of activating a laser beam in accordance with the present invention. In the present embodiment, the output of the continuous wave (CW) laser beam LB of the laser device 1 is used to scan a grain oriented electric plate 1 using a polygonal shell 4 and a f9 lens. By changing the distance between the slant of f0 5 and the oriented granulation electric plate 1, the diameter dl focused in the direction of lamination of the laser beam was changed. 6 is a cylindrical lens or a plurality of cylindrical combination lenses. This is used according to the need to change the focused diameter (length of scan direction) dc from the beam scan direction (plate width direction perpendicular to the rolling direction) to the focused point. the laser beam to control the focus shape from a circular shape to an elliptical shape. The average firing energy density Ua [mJ / mm2] is defined using the laser power P [W], scan speed Vc in the direction of the plate width of the laser beam in the direction of the plate width [m / s]. , and firing pitch of the PL laser in the direction of clearance (mm) as

Ua (mJ / mm 2) = P / (VcxPL).

Laser scan speed is determined by the rotation speed of the polygonal mirror, so that the average laser firing energy density can be adjusted by changing the laser power, the rotation speed of the polygonal mirror and the pitch of the laser. Laser firing. Fig. 1 is an example of using a laser array and laser beam scanning device. It is also possible to place a plurality of similar devices in the direction of the plate width according to the width of the steel plate.

The inventors performed experiments using a continuous-wave fiber laser device with a 10 μm fiber core diameter, changing laser firing conditions, while combining focal point shape and average laser firing energy density. They used the laser beam to scan the surface of the line-oriented grain plate in a substantially vertical direction to the lamination direction to expose it to the laser. They measured the two-dimensional distribution of residual stress in the rolling direction in cross section, vertical to plate width direction and the loss in watt and loss of hysteresis and divided the loss in watt into loss of hysteresis and eddy current loss for study. . To measure the two-dimensional distribution of residual stress in the rolling direction in the cross section, vertical to the plate width direction, they used the X-ray diffraction method to measure the lattice intervals and used the elastic modulus. and other physical property values to convert this to voltage. The loss in watt was measured as W17 / 5o by a Single Sheet Tester (SST) measuring device. [W17 / 50 is the loss in watt at a frequency of 50 Hz and a maximum magnetic flux density. - more than 1.7T. In the sample of oriented grain electric plate used in this example, when the plate thickness is 0.23 mm, the W17 / 50 before laser firing was 0.86 W / kg. Hysteresis loss was calculated by a hysteresis circuit, while eddy current was calculated by taking the loss value in watt minus the hysteresis loss.

Figure 2 shows a typical example of the two-dimensional distribution of the rolling direction compressive residual stress occurring near the laser firing position in a cross section, vertical to the width direction of the plate. For steel sheets, where the best loss in watt is observed, there are differences in the absolute value of the residual stress depending on the laser firing conditions, but there is a large tensile stress near the surface of the steel sheet. There is compressive stress directly below in the direction of plate thickness. Note that the width of the rolling direction, where residual stress and plastic deformation are present, is substantially proportional to the diameter dl of the laser focal point's rolling direction.

The inventors investigated the relationship between the maximum value of the tensile residual stress and the compressive residual stress of the steel plate surface and the loss in watt. The relationship between the maximum traction residual stress value and the loss in watt is shown in figure 3, while the relationship between the maximum compressive residual stress value and the loss in watt is shown in figure 7. For the maximum value of the residual tensile stress, no correlation is observed with the loss in watt or optimal value. On the other hand, for the maximum compressive residual voltage value, the loss in watt is good above 100 MPa, shown by the dash and dot line, but the upper limit value is not clear. As a result, the loss in watt in the laser heating magnetic domain control cannot be explained by the maximum value of the residual tensile stress and cannot be completely explained even by the maximum value of the compressive residual voltage. The possibility of the presence of particularly fine, separate amounts may be considered. Therefore, the inventors studied the data in detail, and as a result observed, as a first point, that the maximum value of elastic residual stress is greater than the compressive residual stress and the residual tensile stress is concentrated at a narrow region, which, depending on the heating conditions, the elastic limit, that is, the plastic deformation region, is reached, whereas, on the other hand, some relationship was observed between the maximum value of the compressive residual stress and loss in watt and, as a second point, even if the maximum value of the compressive residual voltage is the same, there is a difference in the extent of the distribution of the compressive residual voltage in the depth direction. That is, they began to believe that as the main factors behind realizing the reduction in watt loss and realizing the subdivision of the magnetic domain, at a first point, it is not the tensile stress that has significant significance, but, yes, the compressive stress, and in a second point, it is not the maximum value of the residual stress that has important significance, but the extent of the distribution.

To express the compressive stress distribution, to realize the reduction in watt loss, the inventors defined the characterizing amount of the "cumulative compressive stress value aS" as in formula (1) below:

<formula> formula see original document page 9 </formula>

That is, in the two-dimensional distribution of the compressive residual stress in the rolling direction, which occurs near a part exposed to the laser, that is, near the part where deformation is introduced, in the cross section, vertical to the direction of the plate width, defined the cumulative compressive stress value oS [N] as the value of the integrated stress σ in the region S, where the compressive residual stress in the rolling direction is σ [MPa], the cross-sectional region at which the residual stress compressive is S [mm2], and the area element is ds. That is, the cumulative compressive stress value is the sum of the compressive residual stress introduced by laser firing.

The inventors found that the cumulative compressive stress by the above method for an oriented grain plate obtained by adjusting the firing pitch of the PL laser in the rolling direction by 4 mm (fixed) by adjusting the focal point shape of the laser at 20x2500 μm, 100x500 μm, 100x2000 μm and 300x200 μηη, and changing the laser power in each case in stages for laser firing. On the other hand, they subtracted the loss of hysteresis from the loss in watt, measured in each case, to find the loss of eddy current. Figure 4 shows the relationship of the two, for each electrical plate, obtained by plotting the cumulative compressive stress value σS on the abscissa and the loss of parasitic current We on the ordinate. As a result, the cumulative compressive stress value and the eddy current loss are in an inversely proportional relationship, regardless of the focal point shape. This means that the reduction in stray current loss, that is, the subdivision effect of the magnetic domain, is proportional to the sum of the introduced compressive residual stresses. If this phenomenon is considered by physical principles, the result is as follows. The energy of magnetic elasticity E is

E = -CxσxMxcos2θ,

where C is a constant, σ is the residual stress, M is the magnetic moment, and θ is the angle formed by σ and M. In this case, when there is a compressive residual stress in the rolling direction, since E is smaller when θ is 90 degrees, σ is a negative value. Taking this into consideration, the orientation of the magnetic moment becomes vertical to the rolling direction. Therefore, due to the compressive stress, the easily magnetized shaft can be made not only in the direction and bearing, but also in the vertical direction. This is often referred to as a "reflux magnetic domain". If there is a reflective magnetic domain, the magnetostatic energy becomes higher and unstable, so it may be considered to further divide the magnetic domains to lower the magnetostatic energy and stabilize it. Consequently, it is believed that the larger the reflux magnetic domains, that is, the stronger and wider the compressive residual stress generated, the higher the subdivision effect of magnetic domains becomes, and the greater the reduction in the magnetic domain. loss of eddy current. Figure 5 shows the relationship to using the data used in Figure 4 and the measured watt loss, and plotting the cumulative compressive stress value σS over the abscissa and the peak wattage loss W17 / 50 over the ordinate. From the results, in the range of 0.20N≤σS≤0.80N, shown by the dot and dash line, can be performed, compared to the loss in watt W17 / 50≤0.86 W / kg, before the control of magnetic domain, a good watt loss of a watt loss improvement index of 13% or more (W-17 / 50≤0.75 w / kg), shown by the dotted line. Note that the best watt loss index η is defined as η (%) = {(watt loss from peak material watt loss / material watt loss} x100. If the cumulative compressive stress value σS is less than 0.20N, the loss of parasitic current is high, so the loss in watt is not reduced.It is believed that when the value of the cumulative compressive stress σS is greater than 0.80N, the loss eddy current is reduced, but the loss of hysteresis increases due to plastic deformation due to residual tensile stress close to the surface so that the loss in watt is not reduced. that if the cumulative compressive stress value σS is adjusted to the range of

0.20Ν≤σ≤0.80Ν,

A good improvement in watt loss is obtained. Particularly preferred, it is learned that if the value is adjusted to the range 0.40N≤σS≤0.70N, an additional better effect of loss in watt can be obtained.

In this case, the PL laser firing pitch in direction and roll was set at 4 mm, but the inventors further investigated the effects by changing the PL laser firing pitch in direction and bearing. In this case, they shaped the focal point of the laser beam with a diameter of 0.1 mm in the rolling direction and a diameter in the scanning direction (plate width direction) of 0.5 mm and adjusted Ua so that the cumulative compressive stress σS was in the range 0.20N≤σS≤0.80N. Figure 6 shows the graph of the pitch of the PL laser firing in the direction of lamination over the abscissa and the W17 / 50 watt loss over the ordinate and shows the relationship between them. From the results, with a PL of 2 mm to 8 mm, a good watt loss can be realized from a 13% watt loss improvement index. In a range where PL is less than 2 mm, the loss of hysteresis increases, so that the loss in watt is not reduced.

In the range, where PL is greater than 8 mm, the stray current loss is not reduced, so the watt loss is not reduced. From the above, it is learned that by adjusting the firing pitch of the PL laser to the

2 mm <PL <8 mm, a good improvement in watt loss can be obtained. Example 1

Using an oriented granulation electric plate with a thickness of 0.23 mm, the surface of the steel plate was explored using a continuous wave laser under the laser firing conditions as shown in Table 1, the stress The residual value was measured, then the value of the cumulative compressive pressure was calculated and the loss in watt (W17 / 50) was measured. The results are shown together in the same Table 1. Example 1 was performed by setting the laser power at 200 Weo laser firing step in the rolling direction at 4 mm. The cumulative compressive stress value was calculated using the X-ray diffraction method to measure the residual stress (strain) in the rolling direction and find the value with respect to the compressive stress by formula (2).

As is evident from Table 1, the electrical plates shown in Tests No. 1 to No. 8 (examples of the invention) all had a cumulative compressive stress value cS in the rolling direction in the range prescribed by the present invention, i.e. 0.20Ν <σ <0.80Ν so that they could be reduced in watt loss to a low watt loss value (W17 / 50) of 0.75 W / kg for a loss improvement index. in watt of 13% or less. On the other hand, the electrical plates shown in Tests No. 9 to No. 12 (comparative examples), out of the range of conditions of 0.20σ <σ <0.80Ν, failed to achieve a low watt loss value (W17 / 50) of 0.75W / kg or less. Thus, using the present invention, it is possible to obtain a superior oriented grain plate in watt loss. Table 1

<table> table see original document page 14 </column> </row> <table> Example 2

The surface of the 0.23 mm thick oriented granulation electric plate was swept by a continuous wave laser beam under the firing conditions as shown in Table 2, the residual stress of the laser subjected part was measured, then the cumulative compressive stress value was calculated and the loss in watt (W17 / 50) was measured. The results are shown together in the same Table 2. Example 2 was performed by setting the laser power at 200 W, same as in Example 1.

As is evident from Table 2, the electrical plates shown in Tests No. 1 to No. 6 (examples of the invention) all had a cumulative compressive stress value aS in the rolling direction and the laser firing step in the direction. of lamination (deformation step) PL in the ranges prescribed by the present invention, ie 0.20Ν≤σ≤0.80Ν and 2 mm <PL <8 mm, so that they could be reduced in loss in watt to a low watt loss value (W17 / 50) of 0.75 W / kg, for a watt loss improvement rate of 13% or less. On the other hand, the electric plates shown in Tests No. 7 and No. 8 had a cumulative compressive stress value aS that satisfies the conditions but outside the conditions of the heating step PL, and failed to obtain a value of low watt loss (W17 / 50) of 0.75W / kg or less. Thus, using the present invention, it is possible to obtain a superior oriented grain plate in watt loss. Table 2

<table> table see original document page 16 </column> </row> <table> Industrial Applicability

According to the present invention, by the appropriate quantitative control of the residual voltage introduced in the oriented granulation electric plate, particularly the compressive residual voltage, it is possible to stably obtain a higher wattage oriented oriented electric granulation plate. compared to the past. If the oriented granulation electric plate of the present invention is used as an iron core, a small, high efficiency transformer can be produced. The value of the industrial application of the present invention is extremely high.

1. Guided granulation electric plate, obtained by heating with a continuous wave laser beam, to uniformly introduce a deformation in the width direction of the plate, perpendicular to a direction of lamination, cyclically in the direction of lamination, and in lines substantially perpendicular to the rolling direction, characterized in that in the two-dimensional distribution of a compressive residual stress in the rolling direction, which occurs near a location of the deformation introduction in a cross section, perpendicular to the direction of rolling. width of the plate, the value of the compressive residual stress in the rolling direction, integrated in the cross-sectional region where the compressive residual stress is present, is 0,20N to 0,80N.

The oriented granulation electric plate according to claim 1, characterized in that a cyclic step in said uniform deformation lamination direction in said plate width direction due to the heating of the laser beam is of 2 mm to 8 mm.

Claims (1)

1. Fig.1 <figure> figure see original document page 19 </figure>