JP2008160978A - Motor iron-core and motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor iron-core that locally changes magnetic characteristics at a desired site and attains optimization of a magnetic circuit, by enhancing characteristics at a site requiring magnetic characteristics, while maintaining strength at required sections, and to provide a manufacturing method for the iron core and a motor that uses the iron core. <P>SOLUTION: The motor iron-core uses at least one kind of metal selected from among a group consisting of Fe, Ni, and Co as a main component. Its surface has an insulating film. Two or more kinds of powders 12a, 12b, respectively having different magnetic characteristics, are arranged corresponding to sites so as to mold them into a prescribed iron-core shape 10a. Alternatively, a desired part in the iron core whose main phase is an amorphous structure and which is molded into a prescribed shape by using the powders is heated, for example, through induction heating and partially crystallized so as to make the magnetic characteristics of the iron core different, corresponding to sites. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an iron core used as a stator or rotor of an electric motor. More specifically, the magnetic characteristics can be changed depending on the part, and the magnetic circuit can be optimized without losing the overall strength. The present invention relates to an iron core for an electric motor, a manufacturing method thereof, and an electric motor using such an iron core.

For example, in a magnetic member such as a motor rotor or an actuator, a composite magnetic member having a structure in which a nonmagnetic portion or a weak magnetic portion is provided in a part of a ferromagnetic material is used. As a manufacturing method, it is conventionally known to partially change the magnetic characteristics of a magnetic material by partially applying heat to a magnetic material made of a material whose magnetic properties are changed by heating and cooling treatment ( For example, see Patent Document 1.)
JP-A-2005-73456

However, in the technique described in the above-mentioned patent document, the part to be changed the magnetic properties of the magnetic material is individually heated. However, when heating by laser beam irradiation, a lot of processing time is required. Will be required.
Furthermore, since the peripheral portion of the target portion is also heated by heat conduction, there is a region in which the magnetic characteristics change in an inclined manner, and there is a problem that it is difficult to control the magnetic characteristics.

  The present invention has been made in view of the above-described problems in the prior art, and the object of the present invention is to locally change the magnetic characteristics of a desired portion and to increase the strength of a necessary portion. , A magnetic iron core for a motor capable of optimizing a magnetic circuit by improving the characteristics of a portion that requires magnetic characteristics, a method for manufacturing the iron core, and a motor using such an iron core Is to provide.

  As a result of intensive investigations to achieve the above object, the present inventors have found that the above problems can be solved by using two or more types of metal powders having different magnetic properties and using them according to the site. The headline and the present invention have been completed.

That is, the present invention is based on the above knowledge, and the iron core for an electric motor of the present invention is an iron core for an electric motor used as a stator or a rotor, and is selected from the group consisting of Fe, Ni, and Co. Further, it is characterized by comprising at least one kind of metal as a main component, having an insulating film on the surface, and arranging and molding two or more kinds of powders having different magnetic properties according to the part.
In addition, the iron core for an electric motor of the present invention has an amorphous structure as a main phase, is mainly composed of at least one metal selected from the group consisting of Fe, Ni and Co, and has an insulating film on the surface. It is formed by molding powder and is characterized by being crystallized according to the part.

  And in the manufacturing method of the iron core for electric motors of this invention, when crystallizing a part of said iron core for electric motors, the crystallization start part (Tx ) Is placed and heated, or is sintered using a sintered mold in which the thermal conductivity of the portion in contact with the portion to be crystallized is lowered.

  Furthermore, the electric motor of the present invention is characterized by using one or both of the stator iron core and the rotor iron core of the present invention.

  According to the present invention, two or more kinds of powders having at least one metal selected from the group consisting of Fe, Ni, and Co as a main component, having an insulating film on the surface, and having different magnetic properties according to the site. And having an amorphous structure as a main phase, at least one metal selected from the group consisting of Fe, Ni and Co as a main component, and having an insulating film on the surface Optimizing the magnetic circuit by changing the magnetic properties of the desired part locally, and maintaining the strength while increasing the magnetic characteristic of the necessary part, because the molded powder is crystallized according to the part It becomes possible to plan.

  Hereinafter, the iron core for an electric motor of the present invention and the manufacturing method thereof will be described in more detail and specifically.

  As described above, the iron core for an electric motor of the present invention is mainly composed of Fe, Ni, Co, or a metal obtained by arbitrarily combining these, and an insulating film is formed on the surface. A plurality of kinds of metal powders having different magnetic characteristics are arranged according to the part and formed in this state, and the magnetic flux distribution can be adjusted by enhancing the magnetic characteristic of the desired part. For example, the magnetic path It is possible to optimize the magnetic circuit and improve the motor characteristics while maintaining the strength by placing the material with high magnetic characteristics in the part that you want to use as the cover and covering the periphery with the material with low magnetic characteristics Can do.

Specifically, for example, after a part of the iron core is formed by the first powder in another process, a second powder having a magnetic property different from that of the first powder is put in a mold loaded with the formed body. By filling and integrally molding, an iron core having partially different magnetic properties can be formed.
As a result, since the magnetic property changes sharply, there is no intermediate magnetic property region, and it is possible to provide an iron core material with excellent space efficiency.

The metal powder used in the present invention is mainly composed of at least one metal selected from the group consisting of Fe, Ni and Co. In the present invention, the “main component” means the above 3 It means that the total content of metal elements of seeds is 70% or more.
The magnetic properties of these metal powders can be changed by adjusting the amount of the above components, but even if the component content is the same, for example, by adjusting the cooling rate, the crystalline phase (low magnetic The magnetic properties between the powders can also be changed by changing the ratio between the characteristics) and the amorphous phase (high magnetic properties). Moreover, as a particle size of the said metal powder, it is desirable that it is the range of 10-100 micrometers.

  As described later, the insulating film can be formed by subjecting the powder to a phosphate treatment or by applying a coating material (?) Such as a phosphate. Insulates the powder particles to keep the specific resistance high, and demonstrates the function of reducing the core loss of the iron core.

  In the iron core for electric motors of the present invention, the same metal powder as above, and by crystallizing only a desired portion of the iron core formed by using a metal powder having an amorphous structure as a main phase. However, since the magnetic characteristics of the crystallized portion are lowered, the magnetic characteristics of the iron core can be made different depending on the part.

For example, in a stator iron core for an electric motor, a part of the flange portion at the tip of the salient pole can be crystallized.
As a result, the crystallized part with poor magnetic properties becomes a structure that supports the part having an amorphous structure, so that the mechanical strength is improved while the magnetic flux can be effectively concentrated on the flange part. Output will be improved. Furthermore, since ductility occurs in the material by crystallization, mechanical reliability can be improved as compared with the case where the material is composed of only amorphous material.

Moreover, in the rotor iron core for electric motors, the space between magnets inserted in this iron core can be partially crystallized. That is, in the rotor iron core, a hole for embedding a magnet built in the rotor is formed, and the iron core portion between the adjacent magnets around the hole is the N and S poles of the magnet. It is a part through which the magnetic flux wraps around, and it is desirable to block this leakage magnetic flux.
Therefore, if the magnetic properties are degraded by crystallizing the space between the magnets and the magnetic flux passage rate is suppressed, the leakage flux is suppressed and the magnetic flux delivered to the rotor surface side increases. Will be improved. Further, this portion is a portion that supports the centrifugal stress acting on the magnet, and the ductility is improved by crystallization, so that the mechanical reliability is also improved.

  Since the stator iron core and the rotor iron core for an electric motor of the present invention having the above-described structure have the above characteristics, the magnetic circuit can be optimized, and both of them are incorporated into the electric motor. As a result, the output can be greatly improved. Further, by adopting one of them according to the required characteristics, it is possible to produce a low-cost electric motor.

  In the present invention, “having an amorphous structure as the main phase” means that the amorphous phase is dominant over the crystalline phase in the powder cross section.

Then, in order to crystallize a desired portion of the iron core formed using the metal powder having an amorphous structure as a main phase, for example, induction heating can be performed on a portion to be crystallized.
In other words, a crystalline phase can be developed by partially heating and cooling using an induction heating coil, and a large area can be partially formed in a short time without using two or more kinds of powders having different magnetic properties. Thus, it is possible to crystallize and to reduce the magnetic properties of the part. Also, the adjustment in the depth direction can be freely performed by controlling the induced current.

At this time, it is desirable to arrange a powder having a large particle size at a site to be crystallized.
In other words, if a powder having a large particle size is placed in an insulating portion to be crystallized, a larger eddy current is generated in the particle due to the large particle size, so that the portion is easily heated and the crystal is quickly Productivity will be improved.

Similarly, from the viewpoint of improving productivity, a powder with a low resistance film, a thin insulating film, or a powder without a film should be placed at the site to be crystallized. You can also.
That is, a large loop eddy current is generated by this, and it becomes easy to heat early, and productivity is similarly improved.

In order to crystallize a desired portion of an iron core formed using the above metal powder having an amorphous structure as a main phase, an amorphous material having a low crystallization start temperature (Tx) at a portion to be crystallized. It is also possible to arrange and heat the powder.
In other words, in the step of improving the magnetic properties by annealing, the portion made of a powder material having a high Tx that does not cause crystallization is improved in the magnetic properties due to the annealing effect, but is desired to be crystallized from a powder material having a low Tx. Only the portion is deteriorated in magnetic properties by crystallization.

In addition, the cooling rate of the portion in contact with the low thermal conductivity material can be reduced by using a sintered type in which a material having low thermal conductivity is disposed in the portion in contact with the portion to be crystallized during sintering. From this, the desired portion of the iron core can be crystallized.
This eliminates the need for a treatment such as heating after the iron core is formed, and can be formed in a single process, thus greatly improving productivity.

  Hereinafter, the present invention will be described more specifically with reference to the drawings. However, the present invention is not limited to these examples.

(Example 1)
FIG. 1 shows a basic general structure of a stator iron core for an electric motor. A stator 1 shown in FIG. 1 is a split concentrated winding type stator, and includes a plurality of T-shaped stator iron cores ( (Divided core) 10.
A coil C is formed on each salient pole 11 of the stator iron core 10 by winding a necessary number of turns of a conductor wire with an insulating film having a required wire diameter according to characteristics required for the motor. Has been.

  The stator 1 is arranged so that a large number of such stator iron cores 10 are drawn in a circle, and is fixed by, for example, shrink fitting into an aluminum alloy case (not shown), and is incorporated in a motor. In this state, a cylindrical rotor (not shown) is disposed on the inner peripheral side of the annular stator 1 and is rotatably supported by bearings at both shaft ends.

The stator iron core 10 is made of pure iron and press-molded using two types of metal powders 2a (2b) having a shape as shown in FIG. Insulating films 3 were formed on the surface by phosphating.
Each of these metal powders 2a (2b) has a particle size of about 100 μm by water atomizing pure iron melt. Here, as metal powder 2a, Somaloy 500 of Hoganas AB, and metal powder 2b are used. Was used, Somaloy 700, which is a low iron loss material.

In this embodiment, the stator iron core 10a as shown in FIG. 3 was formed by properly using these metal powders 2a and 2b.
Generally, in such a stator iron core, magnetic flux concentrates on a portion such as a corner, resulting in an increase in iron loss (core loss). In this embodiment, first, a metal powder made of a low iron loss material is used. Using 2b (Somaloy 700), a corner member 12 having an L-shaped cross section corresponding to the shape of the corner portion is molded in advance by another molding die, and the corner member 12 is placed in a cemented carbide core molding die. In a state of being attached to a predetermined portion of the above, the remaining portion was filled with metal powder 2a (Somaloy 500) and pressure-molded at a pressure of 800 MPa.

  Thus, in the stator iron core 10a according to this embodiment, the corner portion where the magnetic flux concentrates is made of the low iron loss material powder 2b. Therefore, even if the magnetic flux concentrates on the corner portion, the iron loss is reduced. The motor (electric motor) can be made with a low efficiency.

(Example 2)
First, a metal glass (amorphous metal) powder used as an iron core material was produced by the following procedure.
That is, after a predetermined amount of Fe, Ga, B, Si, Fe—C alloy, and Fe—P alloy is weighed, it is dissolved in Ar gas using a high-frequency melting furnace, and Fe ₇₇ Ga ₄ P _9.5 C _{4 is used.} An ingot having a chemical fraction composition of B ₄ Si _2.5 was produced. The obtained ingot was dissolved again in a reduced pressure Ar atmosphere and sprayed with Ar gas for gas atomization. The atomized powder was classified using a sieve. It was confirmed that the powder thus obtained was a metallic glass.

  Next, the powder was circulated in an air stream by using a fluidized bed type coating apparatus manufactured by POWREC Co., Ltd., and an insulating film agent was sprayed thereon to coat the powder surface to form an insulating film. In addition, phosphate was used as the insulating film agent. At this time, the phosphate is preferably 1% or less by weight with respect to the powder from the relationship between insulation and soft magnetic properties.

The obtained powder was filled into a mold and subjected to SPS sintering (discharge plasma sintering) to obtain a sintered body for a stator core having a substantially T shape having salient poles 11 as described above. At this time, the pressing pressure was set to 600 MPa, and sintering was performed at a temperature lower by 40 ° C. than the glass transition temperature Tg of the metallic glass material.
In addition, since the actual sintered body temperature cannot be measured, the above sintering temperature has been grasped as a condition for obtaining a high-density sintered body without crystallization by repeating many preliminary experiments. .

Next, heat is applied from the surface side to the flange portion 11a at the tip portion of the salient pole 11 of the iron core sintered body thus obtained, and is locally heated, as shown in FIG. The stator core 10b of this example was obtained by partially crystallizing the corner region P on the upper end side in the drawing of the flange portion 11a.
As shown in FIG. 5, the sintered body made of metallic glass has excellent soft magnetic characteristics in the amorphous state, but has crystallized because the saturation magnetic flux density decreases when it is crystallized. The magnetic flux density in the region will decrease.

When designing the iron core using the dust material, the shape of the flange portion 11a at the tip end portion of the salient pole 11 is usually designed to be widened as shown in FIG.
However, since the strength of the powdered material is low, if the thickness t of the flange portion at the tip is too thin, it may not be able to withstand the stress caused by electromagnetic force when driving the motor. The magnetic flux detouring to the salient pole increases and the motor output does not improve.

  In this embodiment, as shown in FIG. 7, the flange portion 11a is formed thick, and by providing a crystallization region P in a part on the winding slot side, the winding slot side direction and the adjacent salient pole tip The magnetic flux does not easily flow into the flange portion, thereby improving the motor output and increasing the thickness of the flange portion 11a on the winding slot side, so that the stress acting on the flange portion 11a is increased. By dispersing, the strength of the iron core 10b can be increased.

(Example 3)
FIG. 8 shows a typical general structure of a rotor for an electric motor. In the rotor iron core 20 in the rotor shown in the figure, a hole for loading a magnet is formed. Is inserted and fixed by an adhesive.
In the case of the illustrated rotor, a leakage magnetic flux that bypasses the side surface of the magnet is generated, and the effective magnetic flux amount that generates torque in opposition to the magnetic flux coming from the stator side is reduced. As shown in FIG. 2, a space Q is provided on the magnet side surface of the rotor iron core 20 so as to provide a barrier that does not bypass the magnetic flux.

  FIG. 10 shows the structure of a rotor iron core according to the present embodiment. In the rotor iron core 20a shown in the figure, the metal glass powder used in the second embodiment is used and the predetermined procedure is performed in the same manner. After sintering to the rotor iron core shape, by locally heating the region R contacting the surface of the magnet 21 that is perpendicular to the magnetic flux direction without providing a flux barrier (space Q) as shown in FIG. By forming the crystallization region R in a part of the space between the magnets, the leakage magnetic flux is reduced without impairing the mechanical strength of the rotor.

Example 4
FIG. 11 shows a case where the corner region P of the flange portion 11a is crystallized by locally heating the flange portion 11a of the tip end portion of the salient pole 11 in the stator iron core 10b in the second embodiment. It is a simplification figure showing the point which applies an induction heating coil.
A high frequency coil 30 corresponding to the shape of the part to be crystallized is used, and the coil 30 is connected to a high frequency power source 31.

When the high-frequency coil 30 is energized, a high-frequency induced current is applied to the stator iron core 10b and heated partially. When the heated portion exceeds the crystallization start temperature Tx, the heated portion is crystallized. Will be converted.
The crystallization start temperature Tx of the metal glass powder used here is about 460 ° C., and is controlled so as to exceed this temperature. Crystallization is possible. Such induction heating can be applied to the side surface of the magnet hole as shown in the third embodiment by using an elongated coil.

(Example 5)
In the metal glass as used in Examples 2 and 3, the crystallization start temperature Tx and the glass transition temperature Tg can be changed by adjusting the components. For example, P (phosphorus) with respect to the composition of the metal glass. There is a tendency that the crystallization start temperature Tx decreases by decreasing the content of Si and increasing the amount of Si (silicon) accordingly.
Therefore, as shown in FIG. 12, the first metal glass powder having a low crystallization start temperature (Tx ₁ ) is disposed in the region P where it is desired to crystallize, while the remaining region has a crystallization start temperature (Tx ₂ ). SPS sintering was performed by filling a second metal glass powder having a high thickness.

And, when annealing to improve the magnetic properties of the obtained sintered body, as shown in FIG. 13, the crystallization start temperature Tx ₁ or more of the first powder disposed in the portion P that is desired to be crystallized, In addition, by annealing at a temperature equal to or lower than the glass transition temperature Tg ₂ of the second metal glass powder having a high crystallization start temperature, the region P to be crystallized is crystallized, and the other part is annealed without being crystallized. Thus, the magnetic properties were improved, and a stator iron core 10c having the same magnetic properties as in Example 2 was obtained.

(Example 6)
In the classifying step, the gas atomized powder obtained in Example 2 is classified into a metal glass powder having an average particle size of 50 μm or more and a metal glass powder having a particle diameter of 38 μm or less, and the same treatment is applied to each of the insulating films. Formed.
Then, as shown in FIG. 14 (a), the coarse powder 2c having an average particle size of 50 μm or more is arranged in the region P where it is desired to crystallize, while the other portions are fine particles having an average particle size of 38 μm or less. The granular powder 2c was filled and SPS sintering was performed in the same manner.

  A stator region having two phases of a crystalline phase and an amorphous phase is crystallized in the desired region P by inductively heating the tip end flange portion 11a of the sintered body thus formed. An iron core 10d was obtained.

At this time, as shown in FIG. 14B, a larger eddy current is generated in the portion of the powder 2c having a large particle size, and the amount of generated heat becomes large, so that it can be heated quickly. It becomes possible to improve productivity. In addition, the powder 2c having a large particle size has a slow cooling rate at the time of powder formation due to the characteristics of atomization. Therefore, the powder 2c is a mixed layer of an amorphous layer containing crystal nuclei and the like and a crystal nuclei. Since it tends to crystallize, it can be said that it is a suitable material for crystallization.
Therefore, in this embodiment, it is possible to provide an iron core having two phases of a crystalline phase and an amorphous phase with a clear boundary in a short time.

(Example 7)
The gas atomized powder obtained in Example 2 was divided into two, and an insulating film was formed only on one side in the same manner as in the above Example.
And as shown in FIG. 15, while arrange | positioning to the area | region P which wants to crystallize the metal glass powder 2e without an insulation film, it fills with the metal glass powder 2d provided with the insulation film in the other part, and the same SPS sintering was performed.

By similarly inductively heating the tip end flange 11a of the sintered body thus formed, the desired region P is crystallized, and in the same manner as in Example 2, two phases of a crystalline phase and an amorphous phase are formed. A stator iron core 10e having the same was obtained.
Thus, by applying the powder 2e without an insulating film to the part to be crystallized,
Since a large loop eddy current is generated in the portion, induction heating is facilitated, crystallization is promoted by a temperature rise, and productivity can be improved.

  In addition, in the said Example, although the example using the powder 2e without an insulating film was shown, the powder which formed the insulating film layer thinner than the powder arrange | positioned in the other part in the part to crystallize, or insulation The same effect can be obtained by using a powder having an insulating film layer having a low property (low resistance value).

(Example 8)
FIG. 16 shows a structural example of a sintered type for a stator iron core used in the present invention. The sintered mold 40 shown in the figure is mainly made of austenitic stainless steel SUS316. A low thermal conductive member 41 made of a ceramic material having a low thermal conductivity is disposed in a portion of the salient pole tip flange 11a that is in contact with the region P to be crystallized.

  By using such a sintering mold 40, the cooling rate of the portion in contact with the low thermal conductivity member 41 is slowed down, so that only one type of metal glass powder is used without being subjected to heat treatment after molding. Only the region P of the tip flange portion 11a, which is a desired portion, can be crystallized in a single step.

It is sectional drawing which shows the basic structure of the stator iron core for electric motors. It is the schematic which shows the shape of the metal powder used for the 1st Example of this invention. It is sectional drawing which shows the structure of the stator iron core obtained by the 1st Example of this invention. It is sectional drawing which shows the structure of the stator iron core obtained by the 2nd Example of this invention. It is a graph which compares and shows the BH curve in the amorphous state and the crystallized state of the sintered compact which consists of metal glass. It is explanatory drawing about the shape characteristic of the stator iron core for electric motors. It is sectional drawing which shows the shape of the collar part of the stator iron core obtained by the 2nd Example of this invention. It is sectional drawing which shows the basic structure of the rotor iron core for electric motors. It is explanatory drawing which shows the example of formation of the flux barrier in a common rotor iron core. It is sectional drawing which shows the structure of the rotor iron core obtained by the 3rd Example of this invention. It is a schematic explanatory drawing which shows the point of the 4th Example of this invention which applied induction heating to the heating of the collar part of a stator iron core. It is a schematic explanatory drawing which shows the point of the 5th Example using the metal glass powder from which crystallization start temperature differs. It is a graph which shows the setting point of the annealing temperature in a 5th Example. It is the schematic explanatory drawing (a) which shows the point of the 6th Example using the metal glass powder from which a particle size differs, and explanatory drawing (b) which shows the principle. It is a schematic explanatory drawing which shows the point of the 7th Example which partially used the metal glass powder without an insulating film on the surface. It is the schematic which shows the structural example of the sintered type for stator iron cores used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stator 2a, 2b, 2c, 2d, 2e Powder 3 Insulation film 10a, 10b, 10c, 10d, 10e Stator iron core 11 Salient pole 11a Gutter part 20a Rotor core 21 Magnet 40 Sintering type 41 Low heat conduction member

Claims (12)

  It consists of at least one metal selected from the group consisting of Fe, Ni and Co as a main component, an insulating film on the surface, and two or more kinds of powders having different magnetic properties arranged and molded according to the site. An iron core for an electric motor.   2. The mold according to claim 1, wherein the second powder having a magnetic property different from that of the first powder is filled and integrally molded in a mold in which a molded body made of the first powder is loaded. Iron core for electric motors.   3. The iron core for an electric motor according to claim 1, wherein the difference in magnetic properties of the powder is based on a ratio between a crystalline phase and an amorphous phase.   Amorphous structure as the main phase, consisting of at least one metal selected from the group consisting of Fe, Ni and Co as a main component, and formed with a powder with an insulating film on the surface, depending on the site An iron core for an electric motor, characterized by being crystallized.   5. The iron core for an electric motor according to claim 4, wherein the iron core for the motor is a stator iron core, and a part of the flange portion at the tip of the salient pole of the stator iron core is crystallized.   The iron core for an electric motor according to claim 4, wherein the iron core is a rotor iron core, and a space between a plurality of magnets inserted into the rotor iron core is partially crystallized.   A method for producing an iron core for an electric motor, wherein when the part of the iron core for an electric motor according to any one of claims 4 to 6 is crystallized, a portion to be crystallized is induction-heated.   8. The method of manufacturing an iron core for an electric motor according to claim 7, wherein a powder having a large particle size is arranged at a site to be crystallized.   At least one powder selected from the group consisting of a powder with an insulating film having a low resistance value, a powder with a thin insulating film thickness, and a powder without a film is disposed at the site to be crystallized. Item 8. A method for producing an iron core for an electric motor according to Item 7.   When crystallizing a part of the iron core for an electric motor according to any one of claims 4 to 6, an amorphous powder having a low crystallization start temperature (Tx) is arranged and heated at a portion to be crystallized. A method for manufacturing an iron core for an electric motor.   A sinter formed by disposing a material having low thermal conductivity in a portion that abuts a portion to be crystallized when crystallization of a part of the iron core for an electric motor according to any one of claims 4 to 6. The manufacturing method of the iron core for electric motors characterized by sintering using a type | mold.   An electric motor comprising the stator iron core according to claim 5 and / or the rotor iron core according to claim 6.

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