GB2104432A - Method and apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet and a grain-oriented electromagnetic steel sheet having a low watt loss - Google Patents
Method and apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet and a grain-oriented electromagnetic steel sheet having a low watt loss Download PDFInfo
- Publication number
- GB2104432A GB2104432A GB08220674A GB8220674A GB2104432A GB 2104432 A GB2104432 A GB 2104432A GB 08220674 A GB08220674 A GB 08220674A GB 8220674 A GB8220674 A GB 8220674A GB 2104432 A GB2104432 A GB 2104432A
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- Prior art keywords
- steel sheet
- grain
- electromagnetic steel
- oriented electromagnetic
- particles
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C3/00—Abrasive blasting machines or devices; Plants
- B24C3/08—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces
- B24C3/10—Abrasive blasting machines or devices; Plants essentially adapted for abrasive blasting of travelling stock or travelling workpieces for treating external surfaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
- B24C1/10—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1294—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a localized treatment
Abstract
The watt loss of a grain-oriented electromagnetic steel sheet can be decreased by known methods in which serrations or scratches are locally formed on said steel sheet or a small ball or disc is rolled or rotated over said steel sheet. The known methods are disadvantageous in that the rate of production is low and in that said steel sheet has a marked unevenness. In the present invention, particles (7), e.g., steel shots, are projected onto substantially linear selected portions (8) of a grain-oriented electromagnetic steel sheet (1), thereby producing strain on spot-formed regions. Spotlike indentations are formed in the steel sheet (1) by the projection of steel shots onto the steel sheet. <IMAGE>
Description
SPECIFICATION
Method and apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet and a grain-oriented electromagnetic steel sheet having a low watt loss
The present invention relates to a method and apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet and a grain-oriented electromagnetic steel sheet having a low watt loss.
Generally speaking, a grain-oriented electromagnetic steel sheet consists of crystal grains, the direction of easy magnetization, i.e. the [100] axis, of which is parallel to the rolling direction, and grain-orientation of a grain-oriented electromagnetic steel sheet occurs during final annealing, in which secondary recrystallization takes place. Grain-oriented electromagnetic steel sheets which are conventionally produced have either a single orientation, in which the (110) plane and [100] axis of the crystal grains are parallel to the sheet surface and the rolling direction, respectively, or a double orientation, in which the (100) plane and [001] axis of the crystal grains are parallel to the sheet surface and the rolling direction, respectively.
Attempts have been made to enhance the degree of orientation of a grain-oriented electromagnetic steel sheet so that the grain-orientation of all of the crystals of the sheet is virtually ideal, or (1 10)[001], in the case of a grain-oriented electromagnetic steel sheet having a single orientation, the reason being that, generally speaking, the exciting characteristic is increased and the watt loss is decreased when the degree of orientation is increased. As a result of these attempts, it is now possible to industrially produce a grain-oriented electromagnetic steel sheet which exhibits a magnetic flux density of 1.7 Tesla when the sheet thickness is 0.3 mm. In order to further reduce watt loss, a method different than the method for enhancing the degree of orientation of a grain-oriented electromagnetic steel sheet must be employed.In other words, it is difficult to further reduce watt loss only by enhancing the degree of orientation, for the reasons given below. The watt loss of a grain-oriented electromagnetic steel sheet is dependent on the exiting characteristic and the grain size. More specifically, the watt loss of a grain-oriented electromagnetic steel sheet can be reduced by enhancing the exiting characteristic and by decreasing the grain size. The exciting characteristic of a grain-oriented electromagnetic steel sheet is usually enhanced by increasing the grain size. The grain size of a grain-oriented electromagnetic steel sheet is conventionally increased by increasing the degree of orientation, but this increase simultaneously involves a factor which disadvantageously increases watt loss and a factor which advantageously decreases watt loss by increasing the exciting characteristic.
It is known to decrease the watt loss of a grain-oriented electromagnetic steel sheet by applying tension to the sheet surface. An industrial method for applying tension to the sheet surface involves the application of an insulating film to the steel sheet. The reduction in watt loss due to the application of an insulating film is, however, limited because the tension applied to the sheet surface by the insulating film is limited. The lowest watt loss attained by means of the industrial tension-applying method mentioned above is approximately 1.03 watts/kg at a frequency of 50 Hz.
It is also known to decrease the watt loss of a grain-oriented electromagnetic steel sheet by means of mirror finishing, such as chemical polishing or electrolytic polishing, occasionally followed by the application of insulating film to the steel sheet. This method for decreasing watt loss is, however, disadvantageous in the respect that watt loss greatly varies depending upon the smoothness of the polished steel sheet. The watt loss of a grain-oriented electromagnetic steel sheet having an insulating film thereon, therefore, also greatly varies because the properties of the insulating film are changed due to the smoothness of the polished steel sheet.
It is proposed in Japanese Laid-open Patent Application No. 50-35679 (1975) that the surface of a grain-oriented electromagnetic steel sheet be serrated or scratched with a knife or an abrasive material so as to reduce watt loss. Serration or scratching unavoidably results in the formation of flaws on a grain-oriented electromagnetic steel sheet and, thus, in an unevenness around the flaws. Consequently, not only is the space factor of the laminated sections of a grain-oriented electromagnetic steel sheet drastically decreased due to the unevenness mentioned above but also the magnetostriction of the steel sheet is drastically increased due to serration or scratching.In addition, burrs, which are formed at both ends of the scratches during scratching, protrude from the sheet surface, and when sections of a grain-oriented electromagnetic steel sheet are laminated, the burrs on said sections protrude through the insulating film applied to the adjacent section. Proposals have been made for eliminating the disadvantages due to serration or scratching and for reducing watt loss to below that attained by enhancing the degree of orientation.
One of the proposals disclosed in Japanese Laid-open Patent Application No. 53-137016 (1978) is that a minute strain be produced in a grain-oriented electromagnetic steel sheet by rolling or rotating a small ball or disc over the steel sheet at a constant pressure. Another proposal disclosed in Japanese Laid-open Patent
Application No. 54-43115 (1979) is that a minute strain be produced in a mirror-finished grain-oriented electromagnetic steel sheet by rolling or rotating a small ball or disc over the mirror-finished steel sheet.
These proposals do, in fact, eliminate the disadvantages due to serration or scratching and reduce watt loss further. However, they still involve problems to be solved from a commercial point of view. One of the problems is that since a small ball or disc is rolled or rotated over a grain-oriented electromagnetic steel sheet so as to produce a minute strain, the steel sheet must either be made stationary or must be conveyed during the production of a minute strain. Another problem is that it is difficult to enhance the production of steel sheets since the relative rolling or rotating speed of a small ball or disc over the grain-oriented electromagnetic steel sheet is limited.
It is an object of the present invention to provide a method by which the watt loss of a grain-oriented electromagnetic steel sheet is reduced by producing a minute strain in the steel sheet, by which flaws which decrease the space factor of the laminated sections of the steel sheet do not occur, and by which the production of steel sheet is enhanced.
It is another object of the present invention to provide an apparatus for carrying out the method mentioned above.
It is still another object of the present invention to provide a grain-oriented electromagnetic steel sheet which has a low watt loss due to strain produced therein and such a good surface property that the space factor of the laminated sections is high.
A method for reducing the watt loss of a grain-oriented electromagnetic steel sheet according to the present invention is characterized in that after final annealing of a steel sheet during which grain-orientation occurs, particles are projected onto substantially linear selected portions of the grain-oriented electromagnetic steel sheet, thereby producing a strain in the spot-formed regions of said selected portions of the grain-oriented electromagnetic steel sheet.
An apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet according to the present invention comprises:
a stationary plate including at least one slit;
a slidable plate capable of reciprocating which is in contact with said stationary plate and includes a slit capable of registering with said at least one slit of said stationary plate; and
at least one means for projecting particles oriented toward said stationary plate.
Another apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet according to the present invention comprises:
a rotatable drum;
a rotatable drum having at least one slit on the cylindrical wall thereof; and
at least one means for projecting particles, said means being located inside or outside said rotatable drum.
A grain-oriented electromagnetic steel sheet having a low watt loss according to the present invention is characterized in that substantially linear selected portions of said grain-oriented electromagnetic steel sheet having spot-like indentations, which are formed due to the projection of particles, and in that strain is produced due to said spotlike indentations.
A grain-orientated electromagnetic steel sheet having a low watt loss according to the present invention is also characterized in that substantially linear selected portions of an insulating film, which is applied to said grain-oriented electromagnetic steel sheet, have spotlike indentations which are formed due to the projection of particles and in that strain is produced in said grain-oriented electromagnetic steel sheet due to said spotlike indentations. The word "grain-oriented electromagnetic steel sheet" herein includes a grain-oriented electromagnetic steel strip.
An apparatus for projecting particles onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing strain in the spot-formed regions of said selected portions said grain-oriented electromagnetic steel sheet, according to the present invention, comprises: an endless conveyor in which slits are formed, said slits being spaced a predetermined distance from each other and elongating in the short width direction of the grain-oriented electromagnetic steel sheet, said endless conveyor facing the grain-oriented electromagnetic steel and being movable at a speed synchronous with the transferring speed of the grain-oriented electromagnetic steel sheet; and a means for projecting the particles, said means being located a predetermined distance from the endless conveyor.
The means for projecting particles may be located outside the closed loop of the endless conveyor but is preferably located inside the closed loop of the endless conveyor.
The endless conveyor is usually located below the grain oriented electromagnetic steel sheet being transferred so that the particles are projected upwards and do not blind the slits. however, the endless conveyor may be located above the grain-oriented electromagnetic steel sheet, if there is a means of preventing blinding of the slits, for example, installing the endless conveyor in a slanted position and transferring the electromagnetic steel sheet in a slanted direction.
A grain-oriented electromagnetic steel sheet contains 4.0% or less of silicon and has been subjected to final annealing, during which grain orientation occurs. Therefore, when a grain-oriented electromagnetic steel sheet is subjected to the projection of particles, it may or may not be provided with an insulating film thereon. The insulating film may be a secondary insulating film composed of a phosphate or an organic compound and may have a thickness of from 1 to 5 microns. In addition, the projection of particles may be carried out after a heat-flattening step.
The projection of particles herein indicates projecting the particles only and projecting the particles together with a fluid, such as air or a gas-fluid mixture, by means of a nozzle.
An apparatus according to the present invention preferably comprises:
a means for projecting particles onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing a strain in the spot-formed regions of said substantially linear selected portions;
a pair of means for measuring the watt loss of the grain-oriented electromagnetic steel sheet in front of and behind the projection of particles, as seen in the direction of the pass line; and
a watt-loss computing circuit for computing the difference in watt loss due to the projection of particles, comparing said difference with a reference watt loss, and controlling the strain energy imparted to said substantially linear selected portions, said circuit being connected to the pair of means for measuring watt loss.
An apparatus according to an embodiment of the present invention comprises:
a means for projecting particles onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing a strain in the spot-formed regions of said selected portions;
a pair of means for measuring the magnetic flux density, said pair of means being located on the pass line of a grain-oriented electromagnetic steel sheet, one of the means being located in front of said means for projecting particles and the other means being located behind said means for projecting particles, as seen in the direction of the pass line;;
a pair of means for applying a magnetic field intensity, said pair of means being located on the pass line of the grain-oriented electromagnetic steel sheet, one of the means being located in front of said means for projecting particles and the other means being located behind said means for projecting particles, as seen in the direction of the pass line; and
a watt-loss computing circuit for computing the difference in watt loss due to the projection of particles, comparing said difference with a reference watt loss and controlling the strain energy imparted to said substantially linear selected portions, said circuit being connected to said pair of means for measuring the magnetic flux density and said pair of means for measuring the magnetic field intensity.
An apparatus according to the present invention preferably further comprises a magnetic-flux density computing circuit for comparing the magnetic flux density of a grain-oriented electromagnetic steel sheet with a predetermined reference magnetic flux density and for controlling the range of the strain energy.
As the projected particles, steel shots, other metal shots, organic resin particles, ceramic particles, and plant material particles can be used. The particles should be an essentially spherical shape.
Embodiments of the present invention are hereinafter explained with reference to the drawings, wherein;
Figure lisa plan view of an embodiment of an apparatus according to the present invention;
Figure 2 illustrates how steel shots are projected onto one substantially linear selected portion of a grain-oriented electromagnetic steel sheet in accordance with the method of the present invention;
Figure 3 which is similar to Figure 2, illustrates how projection of the steel shots is interrupted;
Figure 4 shows embodiments of the substantially linear selected portions of a grain-oriented electromagnetic steel sheet in which strain is produced due to the projection of particles;
Figure 5 is a view of an embodiment of an apparatus according to the present invention;
Figure 6 is a cross-sectional view of the apparatus shown in Figure 5;;
Figure 7 is a view of another embodiment of an apparatus according to the present invention; and projection of particles may be carried out after a heat-flattening step.
Figure 8 is a slide cross-sectional view of an embodiment of an apparatus according to the present invention;
Figure 9 is a view similar to Figure 8;
Figure 10 is a front cross-sectional view of an embodiment of an apparatus according to the present invention;
Figure 11 is a graph showing the magnetic flux density (B8) ad the watt loss (W17/50) obtained as a result of the projection of particles; and
Figure 12 is a block diagram of an embodiment of an apparatus comprising a watt-loss computing circuit.
In Figures 1 through 3, a grain-oriented electromagnetic steel sheet is denoted by reference numeral 1 and is hereinafter simply referred to as steel sheet 1. Steel sheet 1 contains 4.0% or less of silicon and, as stated hereinabove, contains 4.0% or less of silicon and, as stated hereinabove, has been subjected to final annealing, during which grain orientation occurs.
Therefore, when steel sheet 1 is subjected to the projection of particles, steel sheet 1 may or may not be provided with an insulating film (not shown) thereon. The insulating film (not shown) may be a secondary insulating film composed of a phosphate or an organic compound and may have a thickness of from 1 to 5 microns. In addition, the projection of particles may be carried out after a heat-flattening step.
Steel sheet 1 is transferred in the direction indicated by the arrow (Figure 1) and along a pass line.
Stationary plate 3 is disposed above steel sheet 1 so as to maintain a predetermined distance between stationary plate 3 and steel sheet 1. Slidable plate 4 is located on stationary plate 3 and is connected to drive means 5, e.g., a hydraulic or pneumatic cylinder, via piston rod 6. Slidable plate 4 is therefore caused to reciprocate by drive means 5 when slidable plate 4 is in contact with stationary plate 3. Stationary plate 3 and slidable plate 4 are each provided with slit 2, the length of slit 2 being slightly greater than the width of steel sheet 1.Only when both slits 2 register due to the reciprocation of slidable plate 4 is particle-projecting means 10 (Figure 3), which is oriented toward slit 2 of slidable plate 4, actuated so as to project particles, for example, steel shots 7, onto the substantially linear selected portions (hereinafter simply referred to as the selected portions) of steel sheet 1 (Figure 2). Since a number of steel shots 7 impinge upon the selected portions, a number of minute spotlike identations are formed and strain is generated in minute spot-formed regions. Also, since the impinging pattern is determined by the linear shape of slits 2 extending in the short width direction of steel sheet 1,the minute spot-formed regions have a linear configuration.
As the projected particles, not only steel shots but also other metal shots, organic resin particles, ceramic particles, and plant material particles can be used. The particles should have an essentially spherical shape.
Projection of the particles can be carried out together with the injection of a fluid, such as a gas, e.g. air, or a gas-liquid mixture by means of at least one nozzle.
Steel shots are conventionally used to descale rolled steel products. The impinging force of the steel shots according to the method of the present invention may not be as great as in the case of descaling, but an impinging force great enough to lightly strike the surface of steel sheet 1 is sufficient to reduce watt loss. The impinging force can be optionally adjusted depending upon the projection rate, the size, the material, and the hardness of the particles and upon the width of slits 2, as well as upon the tension which may be applied to steel sheet 1 being transferred. As in every method for producing strain in a grain-oriented electromagnetic steel sheet, a very large strain does not reduce watt loss but instead increases watt loss.
In Figure 4, a number of selected portions 8 of steel sheet 1 are linear, are substantially perpendicular to the rolling direction of steel sheet 1, and are parallel to one another. Each of selected portions 8 is a continuous line or curve. Also, each of selected portions 8 may be a discontinuous line 8a or curve 8b. The width (S) of selected portions 8 is preferably from 0.1 to 0.3 mm. The spotlike indentations are indicated in
Figure 4 by reference numeral 11. The surface area of spotlike indentations 11 is considerably smaller than that of selected portions 8. Spotlike indentations 11 have a diameter of from 60 to 80 microns and a depth of from 3 to 5 microns. It is important that the dimension of spotlike indentations 11 be small and narrow so as to reduce the watt loss of steel sheet 1.Steel sheet 1 has no burrs around spotlike indentations 11 because indentations 11 are formed by the projection of steel shots (Figures 2 and 3). The regions of steel sheet 1 where strain is produced are substantially linear. Strictly speaking, such regions are defined by a number of small spot-formed regions which are substantially linearly arranged. Although selected portions 8 are linear and are substantially perpendicular to the rolling direction, the selected portions of a grain-oriented electromagnetic steel sheet having any other pattern may be subjected to the projection of particles. For example, discontinuous or continuous portions, which extend linearly or non-linearly in the rolling direction, may be subjected to the projection of particles.
When steel sheet 1 has an insulating film (not shown) applied thereon prior to the projection of particles, spotlike indentations 11 do not seriously damage the insulating film. In addition, a marked reduction in watt loss is attained, for example, approximately 0.08 watts/kg in terms of W17/50, while at the same time the space factor of the laminated sections of steel sheet 1 is not markedly reduced due to spotlike indentations 11.
The distance between selected portions 8, hereinafter referred to as the linear-strain pitch (p), is optionally selected in the range of from 3 to 10 mm. The linear-strain pitch (p) can be adjusted by adjusting the reciprocating speed of slidable plate 4.
Although one slit 2 is provided for stationary plate 3 and slidable plate 4 in the apparatus shown in Figures 1 through 3, a plurality of slits may be provided for stationary plate 3 and slidable plate 4. In order to decrease the linear-strain pitch (p), the transferring speed of steel sheet 1 must be increased, the reciprocating speed of slidable plate 4 must be increased, or the number of slits 2 must be increased.
Increasing the number of slits 2 is more advantageous for decreasing the linear-strain pitch (p) than is increasing the reciprocating speed since the reciprocating speed is limited due to the construction of slidable plate 4 and drive means 5.
In Figures 5 and 6, an apparatus according to the present invention comprises rotatable drum 9, which can be rotated at a circumferential speed which is synchronous with the transferring speed of steel sheet 1. Slits 2 are formed on cylindrical wall 9a of rotatable drum 9, and the distance between slits 2 corresponds to the linear-strain pitch (p). There are two means for projecting particles, i.e. two impellers 10, one of impellers 10 being located beside one side end of rotatable drum 9 and the other impeller 10 being located beside the other side end of rotatable drum 9. Two impellers 10 project steel shots 7 through apertures 9b of the two side ends of rotatable drum 9 and slits 2 of rotatable drum 9 onto selected portions (not shown in Figure 6).
The device shown in Figures 5 and 6 can be used for treating a steel sheet which is transferred at a high line speed, for example, 100 meters/min or from 200 to less than 1,000 meters/min.
In Figure 7, impellers 10 are located within rotatable drum 9. Although two impellers 10 are shown, there may be only one or more than two provided that the particle projecting means is oriented toward the slits of the rotatable drum.
The apparatuses according to the present invention are practical, simple, and inexpensive from the point of view of installation costs. Since steel shots 7 are recovered by a recovering device (not shown), the operation costs of the method according to the present invention are very low.
In Figures 8 and 9, steel sheet 1 is transferred by means of a coveyor, pinch rollers or another transferring machine (not shown) in the direction indicated by the arrow (Figures 8 and 9) and along a pass line. Endless conveyor 13, in which slits 2 are formed, is installed below the pass line of steel sheet 1 and faces steel sheet 1. Slits 2 are spaced a predetermined distance from each other and elongate in the short width direction of steel sheet 1, i.e., the direction perpendicular to the drawings. Steel sheet 1 may be located directly on endless conveyor 13. A means for projecting particles is installed at a predetermined distance from steel sheet 1.
Centrifugal force is imparted to the particles, i.e., steel shorts 7 (Figure 8), 7a and 7b (Figure 9), and 7c and 7d (Figure 10) by impeller 14 or impellers 14a and 14b or 14c and 14d, and steel shots 7, 7a, 7b, 7c, and 7d are projected onto one of the surfaces of steel sheet 1, i.e., the bottom surface of steel sheet 1. Slits 2 formed in portions of endless conveyor 13, allow steel shots 7, 7a, and 7b to pass therethrough, and the other portions of endless conveyor 13 are shielded from steel shots 7, 7a, and 7b. Therefore, steel shots 7, 7a, 7b, 7c, and 7d are not projected onto the entire bottom surface of steel sheet 1; rather, they are projected onto only selected portions of the bottom surface of steel sheet 1, toward which portions slits 2 are oriented.Since slits 2 elongate in the short width direction of steel sheet 1, said selected portions are substantially linear. In addition, since a number of steel shots 7, 7a, 7b, 7c, and 7d impinge upon the selected portions, a number of minute spotlike indentations are formed and strain is generated in minute spot-formed regions.
Endless conveyor 13 is driven by and is occasionally subjected to tension by rolls 16.
Steel shots 7 (Figure 8) are projected vertically upwards through slits 2 onto steel sheet 1. Steel shots 7a and 7b (Figure 9) and 7c and 7d (Figure 10) are projected upwards but not vertically by impellers 14a and 14b (Figure 9) and impellers 4c and 4d (Figure 10), respectively, which are in a slanted position. Impeller 14 and impellers 14a and 14b and 14c and 14d are located inside cabin 12 of a shot-blasting machine, but they may be located outside cabin 12.
Steel shots 7, 7a, 7b, 7c, and 7d, which impinge on endless conveyor 13 or steel sheet 1, are collected at the bottom part of cabin 12 and are circulated for recycling by means of a collecting and circulating apparatus (not shown).
In Figure 12 a block diagram of an embodiment of an apparatus comprising a watt-loss circuit is shown.
Power sources 21a and 21 b comprise an oscillation mechanism having a commercial frequency and energize exciting coils 23a and 23b of detecting devices 22a and 22b, respectively.
Detecting devices 22a and 22b, respectively, comprise coils 24a and 24b for measuring the magnetic flux density of steel sheet 1 and coils 25a and 25b for applying the magnetic field intensity according to a predetermined measuring condition. Integrator 27 integrates the magnetic field intensity with regard to time, and then the voltage generated due to the magnetic flux density, which voltage is amplified by preamplifier 28, and the integrated voltage, which is generated due to the magnetic field intensity, are multiplied by multiplier 29. The output of multiplier 29 is divided by the output signal of signal generator 31 for setting the cross-sectional area so as to obtain the wott loss of steel sheet 1 before the projection of particles.
Microcomputer 36 subtracts the obtained watt loss from a watt-loss reference signal and produces OUTPUT 2. The watt-loss computing circuit consists of integrator 27, preamplifier 28, mutliplier 29, divider 30, signal generator 31 for setting the cross-sectional area, integrator 32, rectifier 33, divider 34 and microcomputer 36.
OUTPUT 2 of microcomputer 36 is transmitted to first means 26, i.e., the strain-imparting device.
Integrator 32 integrates an induction voltage of coil 24a for measuring the magnetic flux density, and the integrated induction voltage is rectified by rectifier 33. The magnetif flux density of steel sheet 1 is obtained by divider 34 which divides the output signal of rectifier 33 by the output signal of signal generator 31 for setting the cross-sectional area.
Divider 34 and reference-voltage generator 35 form a negative feedback circuit for controlling the magnetic flux density and power sources 21 a and 21 b.
Strain-imparting device 26 may be any means for projecting particles onto selected portions of steel sheet 1, thereby producing a strain in the spot-formed regions of said substantially linear selected portions. One detecting device 22a is located on the pass line of steel sheet 1 in front of strain-imparting device 26, as seen in the direction of the pass line, and the other detecting device 22b is located on the pass line of steel sheet 1 behind strain-imparting device 26, as seen in the direction of the pass line.
Microcomputer 36 generates a signal for periodically switching switches SW1 and 5W2 and controls strain-imparting device 26 in such a manner that: after microcomputer 36 receives the output signal of divider 30, the watt loss of steel sheet 1 after the projection of particles is subtracted from that before the projection of particles so as to obtain the difference in watt loss; when this difference indicates a decrease in watt loss, the strain-imparting force is maintained or adjusted to further increase such difference; and when this difference indicates an increase in watt loss, the strain-imparting force is adjusted so as to decrease watt loss. Strain-imparting device 26 or the strain energy may be controlled by adjusting the particle projection rate.The particle projection rate is preferably from 25 to 30 metres/sec when the magnetic flux density (B8) of steel sheet 1 is approximately 1.95 and is preferably from 20 to 25 meters/sec when the magnetic flux density (B8) iof steel sheet 1 is approximately 1.92 Tesla. OUTPUT 3 of microcomputer 36 is typed out on an output format, and the watt loss before and after the projection of particles, as well as the transferring length of steel sheet 1 given in this output format, is used as information in the further treatment of steel sheet 1.
The present invention is further explained by way of an example.
Example
The projection of particles was carried out by means of the apparatus shown in Figure 3.
Steel sheet 1 had a thickness of 0.30 mm and had the following magnetic properties before the projection of particles: W17180:1.00 Hz 110 1.10watts/kg B8: 1.93 ~ 1.96 Tesla W17/50 is the watt loss at a magnetic flux density of 1.7 Tesla and at a frequency of 50 Hz.
The conditions under which particles were projected were as follows:
Kind of particles:
steel shots 7
Nominal diameter of steel shots 7:
0.3 mm
Actual diameter of steel shots 7:
from 0.1 to 0.4 mm
Projection rate:
from 3 to 30 kg/min/m2
Projection speed (speed of steel shots 7):
from 12 to 52 meters/sec
Linear-strain pitch (P) (distance between slits 2):
10 mm
Width of slits 2:
approximately 0.7 mm
Transferring speed of steel sheet 1:
from 0.3 to 3.0 meters/min W17150, which was measured by SST (measurement of a single sheet), and B8 are given in Figure 11. As is apparent from Figure 11, when the projection speed was appropriately selected, W17/50 was reduced as compared with W17,50 before the projection of particles so that a very low watt loss was achieved. B8 was slightly reduced at a projection speed at which a reduction in W17,50 was achieved. Such a slight reduction in
B8 practically involves no problem.
Claims (16)
1. A method for reducing the watt loss of a grain-oriented electromagnetic steel sheet, characterized in that:
after final annealing of a steel sheet during which grain orientation occurs, particles (7, 7a, 7b, 7c, 7d) are projected onto substantially linear selected portions (8) of the grain-oriented electromagnetic steel sheet (1), thereby producing strain in the spot-formed regions of said selected portions of said grain-oriented electromagnetic steel sheet (1).
2. A method according to claim 1, wherein said particles (7, 7a, 7b, 7c, 7d) are metal particles.
3. A method according to claim 1, wherein said particles (7, 7a, 7b, 7c, 7d) are organic resin particles.
4. A method according to claim 1, 2 or 3 wherein said substantially linear selected portions (8) of the grain-oriented electromagnetic steel sheet (1) are parallel to one another.
5. A method according to claim 4, wherein each of said substantially linear selected portions (8, 8b) of the grain-oriented electromagnetic steel sheet (1) is a continuous line or curve.
6. A method according to claim 4, wherein each of said substantially linear selected portions (8a) of the grain-oriented electromagnetic steel sheet (1) is a discontinuous line or curve.
7. An apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet, comprising:
a stationary plate (3) including at least one slit (2);
a slidable plate (4) capable of reciprocating which is in contact with said stationary plate (3) and which includes a slit (2) capable of registering with said at least one slit (2) of said stationary plate (3); and
a means (10) for projecting particles oriented toward said stationary plate (3).
8. An apparatus according to claim 7, wherein said means (10) for projecting particles is an impeller or nozzle.
9. An apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet, comprising:
a rotatable drum (9) having at least one slit (2) on the cylindrical wall thereof; and
at least one means (10) for projecting particles, said means being located inside or outside said rotatable drum.
10. An apparatus according to claim 9, wherein said at least one means (10) for projecting particles is an impeller or nozzle.
11. An apparatus for projecting particles onto substantially linear selected portions of a grain-oriented electromagnetic steel sheet, thereby producing strain in the spot-formed regions of said selected portions of said grain-oriented electromagnetic steel sheet, comprises: an endless conveyor (13) in which slits (2) are formed, said slits (2) being spaced a predetermined distance from each other and elongating in the short width direction of said grain-oriented electromagnetic steel sheet (1) and said endless conveyor (13) being facing said grain-oriented electromagnetic steel sheet (1) and movable at a speed synchronous with the transferring speed of said grain-oriented electromagnetic steel sheet (1); and a means (14), 14a, 14b, 14c, 14d) for projecting particles (7, 7a, 7b, 7c, 7d), said means being located a predetermined distance from the endless conveyor.
12. An apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet by selectively imparting strain to the surface of said grain-oriented electromagnetic steel sheet comprises:
a means (14, 14a, 14b, 14c, 14d) for projecting particles onto substantially linear selected portions (8) of said grain-oriented electromagnetic steel sheet (1), thereby producing a strain in the spot-formed regions of said substantially linear selected portion (8);
a pair of means (24a, 24b) for measuring the watt loss of said grain-oriented electromagnetic steel (1) sheet before and after the projection of particles (7, 7a, 7b, 7c, 7d); and
a watt-loss computing circuit (27, 28, 29,30, 32, 33) for computing the difference in watt loss due to the projection of particles (7, 7a, 7b, 7c, 7d), comparing said difference with a reference wott loss and controlling the strain energy imparted to said substantially linearw7élected portions (8), said circuit being connected to said pair of means for measuring watt loss (24a, 24b).
13. An apparatus according to claim 12, further comprises:
a pair of means (25a, 26b) for applying a magnetic field intensity, said pair of means being located on the pass line of said grain-oriented electromagnetic steel sheet (1), one of the means (25a) being located in front of said means (14, 14a, 14b, 14c, 14d) for projecting particles and the other means (25b) being located behind said means (14, 14a, 14b, 14c, 14d) for projecting particles, as seen in the direction of the pass line.
14. A grain-oriented electromagnetic steel sheet having a low watt loss, wherein substantially linear selected portions (8) of said grain-oriented electromagnetic steel sheet (1) have spotlike indentations (11) which are formed by the projection or particles, and strain is produced due to said spotlike indentations (11).
15. A grain-oriented electromagnetic steel sheet having a low watt loss, wherein substantially linear selected portions (8) of an insulating film which is applied to said grain-oriented electromagnetic steel sheet have spotlike indentations (11) formed due to the projection of particles, and strain is produced in said grain-oriented electromagnetic steel sheet due to said spotlike indentations (11).
16. A grain-oriented electromagnetic steel sheet according to claim 14 or 15, wherein said spotlike indentations (11) have a diameter of from approximately 60 to 80 microns and a depth of from approximately 3 to 5 microns.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56110858A JPS6056404B2 (en) | 1981-07-17 | 1981-07-17 | Method and device for reducing iron loss in grain-oriented electrical steel sheets |
| JP56153965A JPS5858226A (en) | 1981-09-30 | 1981-09-30 | Reducing device for iron loss of directional electrical steel plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2104432A true GB2104432A (en) | 1983-03-09 |
| GB2104432B GB2104432B (en) | 1985-12-11 |
Family
ID=26450380
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08220674A Expired GB2104432B (en) | 1981-07-17 | 1982-07-16 | Method and apparatus for reducing the watt loss of a grain-oriented electromagnetic steel sheet and a grain-oriented electromagnetic steel sheet having a low watt loss |
Country Status (4)
| Country | Link |
|---|---|
| BE (1) | BE893861A (en) |
| DE (1) | DE3226640A1 (en) |
| FR (1) | FR2510608B1 (en) |
| GB (1) | GB2104432B (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2146567A (en) * | 1983-09-14 | 1985-04-24 | British Steel Corp | Production of grain orientated steel |
| US4533409A (en) * | 1984-12-19 | 1985-08-06 | Allegheny Ludlum Steel Corporation | Method and apparatus for reducing core losses of grain-oriented silicon steel |
| GB2168626A (en) * | 1984-11-10 | 1986-06-25 | Nippon Steel Corp | Grain-oriented electrical steel sheet having stable magnetic properties resistant to stress-relief annealing, and method and apparatus for producing the same |
| EP0302639A2 (en) * | 1987-08-01 | 1989-02-08 | Kawasaki Steel Corporation | Grain oriented electromagnetic steel sheets having a very low iron loss and method of producing the same |
| US5123977A (en) * | 1989-07-19 | 1992-06-23 | Allegheny Ludlum Corporation | Method and apparatus for refining the domain structure of electrical steels by local hot deformation and product thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2208871B (en) * | 1987-08-22 | 1991-03-27 | British Steel Plc | Processing grain-oriented "electrical" steel |
| US4964922A (en) * | 1989-07-19 | 1990-10-23 | Allegheny Ludlum Corporation | Method for domain refinement of oriented silicon steel by low pressure abrasion scribing |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1804208B1 (en) * | 1968-10-17 | 1970-11-12 | Mannesmann Ag | Process for reducing the watt losses of grain-oriented electrical steel sheets, in particular of cube-texture sheets |
| JPS5423647B2 (en) * | 1974-04-25 | 1979-08-15 | ||
| JPS585968B2 (en) * | 1977-05-04 | 1983-02-02 | 新日本製鐵株式会社 | Manufacturing method of ultra-low iron loss unidirectional electrical steel sheet |
| JPS5518566A (en) * | 1978-07-26 | 1980-02-08 | Nippon Steel Corp | Improving method for iron loss characteristic of directional electrical steel sheet |
-
1982
- 1982-07-16 GB GB08220674A patent/GB2104432B/en not_active Expired
- 1982-07-16 FR FR8212960A patent/FR2510608B1/en not_active Expired
- 1982-07-16 BE BE0/208611A patent/BE893861A/en not_active IP Right Cessation
- 1982-07-16 DE DE19823226640 patent/DE3226640A1/en not_active Ceased
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2146567A (en) * | 1983-09-14 | 1985-04-24 | British Steel Corp | Production of grain orientated steel |
| GB2168626A (en) * | 1984-11-10 | 1986-06-25 | Nippon Steel Corp | Grain-oriented electrical steel sheet having stable magnetic properties resistant to stress-relief annealing, and method and apparatus for producing the same |
| US4533409A (en) * | 1984-12-19 | 1985-08-06 | Allegheny Ludlum Steel Corporation | Method and apparatus for reducing core losses of grain-oriented silicon steel |
| EP0302639A2 (en) * | 1987-08-01 | 1989-02-08 | Kawasaki Steel Corporation | Grain oriented electromagnetic steel sheets having a very low iron loss and method of producing the same |
| EP0302639A3 (en) * | 1987-08-01 | 1991-02-06 | Kawasaki Steel Corporation | Grain oriented electromagnetic steel sheets having a very low iron loss and method of producing the same |
| US5123977A (en) * | 1989-07-19 | 1992-06-23 | Allegheny Ludlum Corporation | Method and apparatus for refining the domain structure of electrical steels by local hot deformation and product thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2510608B1 (en) | 1986-05-23 |
| DE3226640A1 (en) | 1983-02-03 |
| FR2510608A1 (en) | 1983-02-04 |
| GB2104432B (en) | 1985-12-11 |
| BE893861A (en) | 1982-11-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |