JP2008036671A - Laminated steel plate of electromagnetic steel having high resistance between steel plates at shear surface thereof, and method for caulking the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out caulking of a laminated steel plate without generating breakage of an insulating film when a steel plate having an insulating film on a surface of an electromagnetic steel plate is punched and the punched steel plates are laminated and are fixed with each other by caulking. <P>SOLUTION: A part of an electromagnetic steel plate is pressed into a die with a punch, and a concavoconvex part for caulking is formed in a part of the steel plate. In this case, the clearance between the punch and the die is made to not less than 3% and less than 7% of the steel plate thickness, so that the insulating film comes into intimate contact with the steel plate shear surface to avoid breakage thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated steel plate of electromagnetic steel having a high steel plate shear surface resistance between steel plates and a caulking method thereof.

  Electromagnetic devices include electric motors, actuators, generators, transformers, reactors, sensors, etc., and many of these are laminated iron cores laminated with electromagnetic steel sheets. Moreover, a steel plate may be laminated | stacked and used as a structural member. In this case, if the laminated steel plates are short-circuited and a current flows, an apparatus or a component using the laminated steel plates may not be able to exhibit performance.

In many iron cores of electric motors, means for binding and fixing laminated steel plates by caulking or the like is used. In addition, when a split iron core is frequently used in an iron core of an electric motor, it is often necessary to bind tooth tips in order to ensure the necessity for handling and rigidity of the tooth tip machine.
In these cases, a part of the steel sheet is sheared by caulking, the shearing surfaces of the laminated steel sheets come into contact after binding, and a short-circuit current flows during use, often resulting in an increase in iron loss.

  Further, even when a laminated body is used as a part of the structural member, a potential may be generated in the laminated body by a magnetic field or an electromagnetic wave generated at an adjacent location, and in that case, the laminated shear planes are in contact with each other. Unnecessary current flows in the apparatus and members, which not only causes loss but also easily generates noise.

  In the present invention, when the steel sheet having the insulating coating formed on the surface of the magnetic steel sheet is punched out and laminated, and the steel sheet is bound by caulking, the insulating coating is applied to the shear surface of the steel sheet so that the above-described problems do not occur. It is an object to provide a method for caulking a laminated steel sheet so as to prevent electrical current from being conducted between shear planes, and a laminated electrical steel sheet having high interlaminar resistance on the electrical steel sheet shear plane. It is what.

In order to solve the above problems, the features of the present invention are as follows.
(1) A caulking method used when a laminated electromagnetic steel sheet is manufactured by punching and laminating an electromagnetic steel sheet having an insulating coating formed on the surface thereof, and binding the steel sheets by caulking, wherein a part of the steel sheet is punched Is formed into a part of the steel sheet to form a rugged portion for caulking, so that the clearance between the punch and the die is 3% or more and less than 7% of the steel sheet thickness, thereby insulating the steel sheet shear plane. The caulking method is characterized in that current is prevented from being conducted between the shearing surfaces of the laminated steel plates without breaking the coating.
(2) When a part of the steel sheet is pushed into the die by the punch, the pushing amount in the thickness direction of the punch is set to 20% to 80% of the plate thickness. This is a caulking method for electrical steel sheets.
(3) A laminated electrical steel sheet obtained by punching, laminating and laminating electrical steel sheets having an insulating coating formed on the surface, and binding the steel sheets with caulking, in the thickness direction of the electrical steel sheet after caulking, in the thickness direction It is a laminated electrical steel sheet characterized in that there is no location where the plate is broken, there is an insulating coating on the shearing surface, and there is no conduction between the shearing surfaces of the laminated steel plates.
(4) A laminated electrical steel sheet obtained by punching and laminating electrical steel sheets having an insulating coating formed on the surface, and binding the steel sheets by caulking, wherein the laminated electrical steel sheets are crimped at a plurality of locations, at least one of which Is a laminated electrical steel sheet characterized by being caulked by the caulking method described in (1) or (2).
(5) The laminated magnetic steel sheet is an iron core used for an electric motor or a generator, and a tooth portion thereof is caulked by a caulking method according to (1) or (2). It is a laminated electromagnetic steel sheet of description.
(6) The laminated electrical steel sheet according to any one of (3) to (5), wherein the insulating coating has a thickness of 2 μm or more and 1% or less of the plate thickness.
(7) The lamination according to any one of (3) to (6), wherein an adhesive is injected between the laminated steel plates or between the shearing surfaces of the crimping portions in order to supplement the caulking binding strength. It is a magnetic steel sheet.

The caulking method and laminated electrical steel sheet according to the present invention do not break the insulating coating on the shearing surface of the steel sheet, so that the insulation between the shearing surfaces of the upper and lower steel sheets to be bound is maintained, and the caulking binding is performed while maintaining a high interlayer resistance. Is possible.
Therefore, when used for an electric core or a generator core that often uses caulking, since there is an insulating coating on the shearing surface, it is possible to reduce the iron loss of the equipment without energizing the shearing surface. In particular, it is more effective when used for a high-frequency motor or a high-speed motor excited at a high frequency.

  In addition, the caulking method and laminated electrical steel sheet of the present invention can be applied to a normal insulating film by regulating the punch-to-die clearance, the punch push-in amount in the plate thickness direction, and the insulating film thickness. The interlaminar resistance between the plates can be kept high without breaking. Furthermore, when an insulating coating containing a thermosetting resin or a thermoplastic resin is used, a laminated electrical steel sheet having an increased interlayer resistance on the shear plane and an increased adhesion between the shear planes can be obtained.

  Further, by applying the caulking method and laminated electrical steel sheet according to the present invention to a part that is more susceptible to iron loss due to concentration of magnetic flux, for example, binding of teeth of an iron core of a motor or a generator, iron loss is further reduced. Can be obtained.

  In the present invention, when an electromagnetic steel sheet having an insulating coating formed on the surface is punched and laminated, and the steel sheets are bundled by caulking, the insulating coating adheres to the shear surface of the steel sheet when a part of the electromagnetic steel sheet is pushed into the die by a punch. Thus, there is a caulking method for an electrical steel sheet characterized by preventing current from being conducted between shear planes without breaking, and a laminated electrical steel sheet bound by applying such caulking method.

  When punching, laminating and binding the electromagnetic steel sheets by caulking, before punching the electromagnetic steel sheet 1, as shown in FIG. Form. The electromagnetic steel sheet on which the uneven portions are formed is then punched into a predetermined shape and simultaneously laminated on the steel sheet punched immediately before. At this time, the convex portions of the steel plate punched this time are fitted into the concave portions of the steel plate previously punched, and these steel plates are caulked. This caulking is usually performed at a plurality of locations on the laminated steel sheet.

The above operation is repeated a predetermined number of times to produce a laminated electrical steel sheet in which a predetermined number of electrical steel sheets as shown in FIG.
As the form of caulking used, round flat caulking using a circular or elliptical punch as shown in FIG. 2 (a), or V caulking using a V-shaped punch as shown in FIG. 2 (b). and so on.
Here, caulking means caulking peculiar to laminated electromagnetic steel sheets as shown in FIG. 2, and “Metal Handbook (4th revised edition)” (issued by Maruzen), page 1711, (d) to (h) in FIG. ) Is a different technology from caulking.

As described above, for the crimping of the laminated electrical steel sheet, a part of the electrical steel sheet is pushed into the die 3 by the convex punch 2 to form the uneven part. In this case, in the case of round flat caulking, the side wall of the uneven part is formed. In the case of V caulking, the shear surface 4 is formed on the left and right side walls of the uneven portion.
In the present invention, the interlaminar resistance between the laminated steel sheets is kept high so that the insulating coating on the shear surface of the steel sheet remains unbroken during caulking.

Hereinafter, caulking conditions for doing so will be described.
In order to keep the insulating coating on the shear surface of the steel sheet without breaking during the caulking process, the clearance between the convex punch and the die used for caulking and the pushing amount of the convex punch are particularly important.

It is said that the clearance at the time of processing the conventional electrical steel sheet is 7% to 11% of the plate thickness as shown in Table 15.8 on page 1711 of the "Metal Handbook (4th revised edition)". In order to prevent the insulating coating from being broken in the caulking when laminating and bundling, it has been found that the clearance should be 3% or more and less than 7%, which is smaller than the clearance of 7% to 11% of the conventional processing die.
Here, as shown in FIG. 3, the clearance refers to the gap between the convex punch and the die (half of the difference between the width of the punch and the inner width of the die) and the thickness of the steel plate (t in FIG. 1). The value (%) divided by is defined as clearance.

  If the clearance is less than 3%, the insulating film does not break in the above range, and the gap between the convex portion and the concave portion of the electromagnetic steel sheet is too small, and the insulating coating is often rubbed and broken. Further, it is considered that when the clearance is 7% or more, the gap between them is too far and the caulking itself does not associate well, and the insulating coating often breaks.

Further, when a part of the steel plate is pushed into the die by the convex punch, the pushing amount in the thickness direction of the convex punch (s in FIG. 1) is preferably 20% or more and 80% or less of the plate thickness. .
If the caulking depth is equal to or greater than the processing sag, the laminated shape can be maintained, but since the size of the normal processing sag is smaller than 1/5 of the plate thickness, if the pushing amount of the punch is 20% or more of the plate thickness Good. In addition, the caulking depth is preferably 80% or less of the plate thickness so that the claws (projections) of the caulking portion do not separate from the steel plate. On the contrary, if it is less than 20%, the caulking depth is shallow, so that the laminated steel plate is detached and the caulking itself is no longer meaningful, and if it exceeds 80%, the plate itself breaks to form a fracture surface. Therefore, the insulating coating is naturally broken, and the interlayer resistance of the shearing surface cannot be maintained.

The thickness of the insulating film formed on the surface of the steel plate may be thin as long as the interlayer resistance of the plate sheared surface after crimping can be maintained high, but to keep the interlayer resistance after crimping high, the thickness is 2 μm or more. Is preferred. Moreover, since the function (space factor) as a magnetic member will fall if the film thickness is too thick, considering the space factor of the laminated electromagnetic steel sheet to be 98% or more, the plate thickness corresponding to the space factor 1% or less is preferable.
Therefore, the thickness of the insulating coating is preferably 2 μm or more and 1% or less of the plate thickness.

The insulating film may be any film such as an insulating oxide film, an organic or inorganic insulating film, or a semi-organic insulating film. The insulating oxide film may be any of those generated by heat treatment in the manufacturing process of the electrical steel sheet and those formed by blueing or the like.
Further, the insulating film may contain a thermosetting resin or a thermoplastic resin. As the insulating film containing the thermosetting resin or the thermoplastic resin, there is an adhesive film that exhibits adhesive ability by heating. This includes a thermosetting resin or a thermoplastic resin, and specifically includes an acrylic resin or an epoxy resin as a main component.

  In addition, when the caulking depth is shallow, the binding strength between the laminated steel plates becomes small. Therefore, in order to supplement the binding strength, another method of binding between the laminated steel plates may be further provided. As another bundling method, laminated magnetic steel sheets may be molded (bumped), or the adhesive may be bonded by dipping the adhesive between the board layers to dry them, or bonding that exhibits adhesive ability by heating. The bundling force may be increased after heating using a magnetic steel sheet provided with a coating. That is, the adhesive may be an adhesive film that exhibits adhesive ability with an insulating film containing a curable resin or a thermoplastic resin as described above.

In order to efficiently use the caulking method described above, it is preferable to apply only to a portion where an induced electromotive force is generated in the caulking portion. For example, in the outer field stator of the motor of the outer armature stator, there is a caulking applied to the outer peripheral portion and a caulking applied to the tooth portion, and almost no induction is applied to the caulking of the outer peripheral portion. Although no electromotive force is generated, the induced electromotive force is increased in the caulking of the tooth portion. Therefore, the caulking method of the present invention is effective for caulking the tooth portion.
Therefore, as in Example 4 to be described later, the caulking of the present invention may be applied only to a portion where the induced electromotive force is increased.

  The laminated electrical steel sheet using the caulking method of the present invention has an effect of suppressing a short-circuit current when used in alternating magnetic flux excitation, so that it can be used for transformers, electric motors and generators, and electromagnetic energy conversion devices such as choppers. When used for an iron core or a resolver iron core, eddy current loss can be suppressed. Bundling by caulking is usually used in the manufacture of electric motors and generators, and the caulking method of the present invention can be suitably used, but the efficiency of electric motors and generators is particularly improved when applied to the teeth of the core. Can be high.

  Furthermore, the present invention is based on the premise that a film remains on the shearing surface and no electrical conduction exists between the plate layers without forming a fracture surface, but even if a fracture surface exists, the fracture surface does not contact (space). Alternatively, it may be possible to prevent continuity by the method of binding between laminated steel plates as described above. In short, it is only necessary to prevent conduction between laminated steel plates after crimping.

  Examples of the present invention will be described below, but the conditions adopted in the examples are one example of conditions for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. It is not something. The present invention is defined only by the matters described in the claims of the claims, and various conditions can be adopted as long as the object of the present invention is achieved without departing from the present invention. .

In this embodiment, an example is shown in which the clearance between the convex punch used for caulking and the die is changed from 2% to 10%.
Using 10 electromagnetic steel sheets with a thickness of 0.35 mm, a laminated electromagnetic steel sheet was prepared by round flat caulking with a pressing amount of a convex punch in the thickness direction of 50%, and the short circuit resistance between the laminates was measured. As a result, in the conventional caulking method in which the clearance is 2% and 10% of the plate thickness, the short-circuit resistance between the laminates of the ten laminated steel sheets was 1.0 to 1.2 mΩ. In the case of 3%, 5%, and 6.9%, the short-circuit resistance was 20 to 40 mΩ.

  In the case of the example of the present invention, as shown in FIG. 4 (b), the steel plate in the crimped portion is not broken and is in contact only with the shear plane. This sheared surface is smooth and the insulation film of the electromagnetic steel sheet remains, and it is considered that the contact resistance can be kept high because the insulating layer of the electromagnetic steel sheet that comes in contact is not damaged.

On the other hand, in the conventional case, in the machining with a large clearance (clearance 10%), as shown in FIG. 4A, most of the caulking parts are broken, and the boundary between the sheared part and the broken part on the machined surface is broken. Since the corrugated surface is rough and the insulating coating of the electromagnetic steel sheet is not attached, the sheared part between the steel sheets and the fractured part are in contact with each other, or the insulating coating of the contacting electromagnetic steel sheet is torn, It is thought that conduction occurs because there is no resistance between the electrical steel sheets.
In addition, it is considered that even in processing with a small clearance (clearance of 2%), the gap is too small, and the insulating coating is rubbed and broken during lamination, thus causing conduction.

The above results are summarized in Table 1.

In this embodiment, an example is shown in which the amount of pushing the convex punch in the thickness direction is changed from 10% to 90% of the thickness.
In the same manner as in Example 1, ten electromagnetic steel plates having a thickness of 0.35 mm were rounded and flattened with the clearance of 5% to prepare laminated electromagnetic steel plates, and the short circuit resistance between the laminated steel plates was measured.

When the push-in amount was 90%, the short circuit resistance between the layers was 1.0 to 1.2 mΩ, and most of the crimped portions were broken.
On the other hand, when the pushing amount was changed from 20% to 80% of the present invention, the short circuit resistance was 20 to 40 mΩ, and no breakage was observed in the crimped portion.
When the indentation amount was 10%, the short circuit resistance was 20 to 40 mΩ, and no breakage was observed in the crimped portion, but the indentation amount was small and the laminated steel plate was easily removed.

The above results are summarized in Table 2.

In this example, an example in which the thickness of the insulating coating is changed to 1.5 μm to 4 μm (1.1% of the plate thickness) is shown.
In the same manner as in Example 1, ten electromagnetic steel sheets having a thickness of 0.35 mm were rounded and caulked with the clearance of 5% and the protruding amount of the convex punch of 50% to prepare a laminated electromagnetic steel sheet, and a short circuit between the laminated steel sheets. Resistance was measured.

  Except for the case where the thickness of the insulating coating is 1.5 μm, the short circuit resistance between the layers is 20 to 40 mΩ, and the clearance and the push-in amount of the convex punch are within the range of the present invention. There wasn't. When the thickness of the insulating coating is as thick as 4 μm (1.1% of the plate thickness), the space factor decreases.

The above results are summarized in Table 3.

As shown in FIG. 5, in the brushless DC motor, when the inner rotor is a field and the outer stator is an armature, the locations 13 and 14 of the core yoke portion width 1/10 from the outer periphery of the stator core 11 and the core The teeth 12 were crimped under different conditions.
As shown in Table 4, when the loss generated in the core was measured by the iron loss torque, the iron loss was separated by the two-frequency method, and the eddy current loss was obtained, the conventional caulking with a large clearance between the convex punch and the die was obtained. Assuming that the eddy current loss of the core using (conventional caulking) is 100, when caulking (the caulking of the present invention) that satisfies the conditions defined by the present invention is used for all caulking, the average is 47. For the caulking of the yoke outer peripheral parts 13 and 14, the conventional caulking was used, and for the tooth part 12, the caulking of the present invention was 49 on average.

In this embodiment, when the caulking depth (indentation amount) is shallow, the binding strength between the laminated steel sheets becomes small. Therefore, in order to supplement the binding strength, the laminated electrical steel sheets are molded (striking) or an adhesive is used. An example is shown in which the laminated steel sheets are injected and dried to bond the laminated steel sheets.
Table 5 shows the results of increasing the interlaminar binding force by the above method when the amount of pushing the convex punch in the caulking thickness direction is 20%.
The interlaminar binding force was improved in both the case where the laminated electromagnetic steel sheet was applied to the varnish and the case where acrylic resin or epoxy resin was injected as an adhesive between the laminated steel sheets.

As shown in FIG. 6, caulking was performed on the split iron core used in the embedded magnet type synchronous motor. In FIG. 6, V caulking 16, 17 was used for the yoke portion of the split core 11, and the round flat caulking 15 of the present invention was used for the tooth portion in the same manner as in Example 1.
When comparing the no-load iron loss of the motor with the conventional round flat caulking of the tooth portion 15, the iron loss was reduced by about 20% when the round flat caulking of the present invention was used.

In making the split iron core of Example 6, it was immersed in a solution that could be insulated and bonded only by drying, and then dried. In the caulking, the amount of pushing is kept to a depth of about 1/4 of the thickness that can maintain the shape of the laminated core. However, since the laminate can be bonded and bonded by a solution that can be insulated and bonded only by drying, the iron core is used in the winding process. Can withstand the stress applied to
Conventionally, there is a method of binding between layers with a solution that can be insulated and bonded only by drying without caulking, but in this example, the core shape is maintained by using the caulking of the present invention in the punching process and only dried. By using an insulating coating that can be insulated and bonded, a high-strength iron core that suppresses a short circuit between layers can be realized.

  In making the split iron core of Example 6, an adhesive-coated magnetic steel sheet was used, and after caulking, an adhesive treatment was performed at 200 ° C. Compared with the split iron core using the magnetic steel sheet with the conventional coating, there was almost no difference in resistance between the laminations, but in the 1m drop test, the split iron core using the magnetic steel sheet with the conventional coating was However, although the caulking depth was shallower than before, it was separated and destroyed, but there was no problem with the iron core using the adhesive-coated magnetic steel sheet.

  In making the split iron core of Example 6, a magnetic steel sheet having a coating applied to the surface of 2.5 μm thicker than the conventional 1.5 μm was used. Compared with a split iron core using a magnetic steel sheet coated with a conventional thickness, the resistance between the layers was 1.3 times.

  In a spiral iron core using a normal steel plate with a thickness of 1 mm that contains almost no silicon, simultaneously with slot production by notching, the caulking part is processed by the caulking method of the present invention, and after spiral bending, pressurization in the laminating direction is performed. United. The iron core was press-fitted into the spiral generator case to make a generator. The caulking was performed at three locations in the center of the iron core relay section. When the loss torque was obtained from the power generation characteristics, the eddy current loss was reduced by 14% compared to the case of the conventional punched laminated caulking.

  When the caulking method of the present invention is applied to a resolver iron core used as a sensor of a motor, the short circuit resistance between layers increases, and the electrical error due to variation in the short circuit resistance between layers can be reduced by about 10% compared to the conventional caulking. It was.

  The present invention is adopted for the core of the reactor. The reactor is a combination of four I-types, but in order to suppress the vibration of the laminated steel sheets that make up the iron core, the four corners of the I iron core were crimped. Compared with the case where the conventional clearance was crimped at 10% of the plate thickness, the loss was reduced to about 1/3 in the case where the clearance was performed with the clearance of 5% of the present invention.

It is a figure for demonstrating the crimping method of this invention. It is a figure for demonstrating the crimping of a laminated steel plate, (a) is sectional drawing and front view in the case of a round flat crimping, (b) is sectional drawing and a front view in the case of V crimping. It is a figure for demonstrating clearance. It is a schematic diagram which expands and shows the cross section after crimping, (a) is sectional drawing by the conventional crimping method, (b) is sectional drawing by the crimping method of this invention. It is explanatory drawing of the crimping part of a stator core. It is explanatory drawing of the other example of the crimping part of a stator core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic steel plate 2 Convex punch 3 Dies 4 Shear surface 11 Divided core 12-17 Caulking location

Claims (7)

  A caulking method used to produce a laminated electrical steel sheet by punching, laminating and laminating electrical steel sheets having an insulating coating formed on the surface thereof, and binding the steel sheets with caulking. When forming the rugged portion for caulking on a part of the steel sheet by pushing into the steel sheet, the insulation film on the shear surface of the steel sheet is broken by setting the clearance between the punch and the die to be 3% or more and less than 7% of the steel sheet thickness A caulking method characterized in that current is prevented from being conducted between the shearing surfaces of the laminated steel sheets.   2. The caulking method according to claim 1, wherein when a part of the steel plate is pushed into the die by the punch, the pushing amount in the thickness direction of the punch is set to 20% to 80% of the steel plate thickness. .   A laminated electromagnetic steel sheet in which an electromagnetic steel sheet having an insulating coating formed on the surface is punched and laminated, and the steel sheets are bound by caulking, where the plate is broken in the thickness direction in the thickness cross-sectional shape of the electric steel sheet after caulking A laminated electrical steel sheet characterized by having no insulation film on the shearing surface and no conduction between the sheared surfaces of the laminated steel sheets.   A laminated electrical steel sheet obtained by punching and laminating electrical steel sheets having an insulating coating formed on the surface, and binding the steel sheets with caulking, the laminated electrical steel sheets being crimped at a plurality of locations, at least one of which is claimed 3. A laminated electrical steel sheet characterized by being caulked by the caulking method according to item 1 or 2.   The laminated electromagnetic steel sheet according to claim 4, wherein the laminated electromagnetic steel sheet is an iron core used for an electric motor or a generator, and a tooth portion thereof is caulked by a caulking method according to claim 1 or 2. .   The laminated electrical steel sheet according to any one of claims 3 to 5, wherein the thickness of the insulating coating is 2 µm or more and 1% or less of the steel sheet thickness.   The laminated electrical steel sheet according to any one of claims 3 to 6, wherein an adhesive is injected between the laminated steel sheets or between the shearing surfaces of the crimped portions.

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