WO2021096292A1

WO2021096292A1 - Method for manufacturing shaped body comprising insulating layer, and method for manufacturing stator for axial flux motor, comprising insulating layer

Info

Publication number: WO2021096292A1
Application number: PCT/KR2020/015999
Authority: WO
Inventors: 정재원; 양상선; 유지훈
Original assignee: 한국재료연구원
Priority date: 2019-11-14
Filing date: 2020-11-13
Publication date: 2021-05-20
Also published as: KR102413796B1; KR20210059137A

Abstract

The purpose of the present invention is to provide a yokeless stator for an axial flux motor, and a method for manufacturing same. To this end, the present invention provides a yokeless stator for an axial flux motor, and a method for manufacturing same, the yokeless stator for an axial flux motor comprising: a hollow stator core which is extended in the vertical direction; a shoe which is integrated with the stator core on the end of the extending direction of the stator core; and an electrical steel sheet segment which is inserted in the hollow stator core, is formed by laminating a plurality of electrical steel sheets which have the same width or mutually different widths, and has a multi-tier block structure by means of the formation of respective blocks of electrical steel sheets of the same width, wherein the inner surface of the stator core is formed so as to correspond to the outer surface of the electrical steel sheet segment which has the multi-tier block structure, and the shoe protrudes to the outer side of the stator core in all directions in the horizontal direction. According to the present invention, motor efficiency may be greatly improved by reducing iron loss caused by an eddy current occurring in the stator of the axial flux motor.

Description

A method of manufacturing a model including an insulating layer and a method of manufacturing a stator for an axial magnetic flux motor including an insulating layer

The present invention relates to a method of manufacturing a model including an insulating layer and a method of manufacturing a stator for an axial magnetic flux motor including an insulating layer.

In general, a motor is a device that converts electrical energy into mechanical energy to obtain rotational force, and is widely used in a wide range of fields ranging from household electronic products to various industrial devices. Such a motor mainly consists of a stator in which a coil is wound to form a rotating magnetic field by the application of power while being fixed to a housing or casing, and a rotor that is rotatably installed by a shaft inside the stator, and a stator is generated. The magnetic flux that makes it interacts with the rotor and is formed to generate rotational torque.

On the other hand, in recent years, active research and development on another type of vehicle, that is, a hybrid vehicle or an electric vehicle, which is environmentally friendly and considers fuel efficiency in a vehicle using a combustion engine, has been conducted. Hybrid vehicles drive vehicles with two power sources by linking conventional combustion engines and electric drive motors, and electric vehicles are driven by electric motors, reducing environmental pollution caused by exhaust gas and improving fuel economy. This is possible, and it is positioning itself as a next-generation car that is realistically alternative. In the hybrid vehicle or electric vehicle as described above, the motor is positioned as a key component enough to influence the overall vehicle performance, and the development of a high-power, miniaturized motor is emerging as a hot topic in hybrid vehicles and the like.

The axial magnetic flux motor includes a stator that forms a magnetic field and a rotor that is rotatable with respect to the stator. The stator includes a plurality of cores that are disposed at regular intervals along the circumferential direction and protrude to a predetermined height in the axial direction, and the core has a structure coupled in the axial direction to, for example, a groove formed in the stator body. The rotor includes permanent magnets arranged at regular intervals along the circumferential direction, and is configured to rotate while forming a regular interval with the stator. The axial magnetic flux motor generates a repulsive force or a suction force between the core and the permanent magnet of the rotor by changing the direction of the current flowing through the winding to generate rotational torque.

Republic of Korea Patent Publication No. 10-1207608 discloses a plate type rotating machine as described above. The disclosed flat-panel rotating device includes a housing, a rotation shaft rotatably installed on one side and the other side by supporting each of the one side and the other side of the housing, a ring-shaped first support plate coupled to the housing, and the center of the first support plate. A plurality of first tooth cores radially coupled to one surface of the first support plate, a bobbin each coupled to an outer surface of the other surface of the first tooth core, and a coil wound around the bobbin of the housing. In the plate-shaped rotating machine comprising a flat ring-shaped stator installed inside, a plate-ring-shaped rotor coupled to the rotation shaft located inside the housing and rotating by working with the stator to rotate the rotation shaft, wherein the The first support plate is provided with a first coupling rail having a "T" shape in a cross-sectional shape in the width direction, and the first coupling rail is coupled to the first support plate by a fastening member, and the first chi-core A first press-fit groove formed in a shape corresponding to the first coupling rail and press-fitted to the first coupling rail is formed on one end surface of the first coupling rail, and the first tooth core coupled to the first support plate The outer surface of one surface side is further protruded outward than the outer surface of the other surface to be in contact with each other, and the outer surface of the other surface side of the first chi core is spaced apart from each other, and the bobbin is coupled.

The plate-type rotating machine constructed as described above manufactures a tooth-shaped core by laminating silicon steel sheets of different sizes. For this reason, in order to form silicon steel sheets of different sizes, it is necessary to manufacture a mold suitable for each shape, or a process of laminating and cutting silicon steel sheets of the same size, etc., so that the manufacturing process is not only complicated, but also Due to this, there was a problem that the manufacturing cost was increased.

Accordingly, in recent years, since the powder is compacted to form a shape, a soft magnetic composite (SMC), which is easy to form a complex shape, has been used.

However, in the case of using an integral core that is molded and extruded using soft magnetic powder, there is an advantage in that it is easy to manufacture, but compared to a core shaped by stacking electrical steel sheets, high core loss occurs, resulting in poor magnetic properties. There was this.

It is an object of the present invention to provide a method of manufacturing a model including an insulating layer and a method of manufacturing a stator for an axial magnetic flux motor including an insulating layer.

To this end, the present invention forms a model including an open void extending from one side or both sides of the model to the inside of the model through 3D printing, and the open gap does not penetrate the model. The step of doing; Performing an insulating coating on the surface of the pores; And performing one-way compression or isotropic compression to remove voids. In addition, the present invention is, through 3D printing, an open pore extending from one side or both side portions of the stator for an axial magnetic flux motor to the inside of the stator, the axis including an open pore that does not penetrate the stator Forming a stator for a directional magnetic flux motor; Performing an insulating coating on the surface of the pores; And it provides a method of manufacturing a stator for an axial magnetic flux motor comprising an insulating layer comprising; and performing one-way compression or isotropic compression to remove the voids.

According to the present invention, there is an effect that a molded body including an insulating layer therein can be manufactured by an easy method. In addition, according to the present invention, it is possible to greatly improve the efficiency of the motor by reducing the iron loss due to the eddy current generated in the stator of the axial magnetic flux motor. In addition, according to the present invention, by manufacturing a stator of an axial magnetic flux motor by a 3D printing method, a complex structure that is difficult to implement in the past is easily implemented, thereby effectively reducing iron loss in the stator, while preventing the saturation magnetic flux density from deteriorating. There is an effect that can be done.

1 is a schematic diagram showing a manufacturing method of the present invention,

2 is a specific example of an open void manufactured by the manufacturing method of the present invention,

3 is another specific example of the open pores manufactured by the manufacturing method of the present invention,

4 is a graph showing the effect of the insulating layer of the stator manufactured by the manufacturing method of the present invention,

5 is a graph showing the effect according to the width between the insulating layers of the stator manufactured by the manufacturing method of the present invention,

6 is a graph showing the effect according to whether or not heat treatment is performed in the manufacturing method of the present invention,

7A, 7B, and 7C are schematic diagrams showing specific examples of a stator manufactured by the manufacturing method of the present invention,

8 is a diagram comparing the structure of a radial magnetic flux type motor and an axial magnetic flux type motor,

9 is a diagram showing the structural difference between a general radial magnetic flux type motor and a yokeless axial magnetic flux type motor,

10 is a graph showing the relative density and surface roughness of a shaped object according to the heat treatment temperature,

11 is a graph showing the iron loss reduction effect according to the heat treatment temperature,

12A, 12B, and 12C are photographs showing a method of manufacturing a high-density molding agent and a graph showing the saturation magnetization value of the modeled body accordingly, and

13A, 13B, 13C, and 13D are cross-sectional SEM photographs according to heat treatment conditions of the sculpture.

The present invention provides a method of manufacturing a sculpture including an insulating layer, and more specifically, through 3D printing, an open pore extending from one side or both side portions of the sculpture to the inside of the sculpture, the open pore is Forming a sculpture including an open void not penetrating the sculpture;

Performing an insulating coating on the surface of the pores; And

It provides a method of manufacturing a sculpture including an insulating layer comprising; performing one-way compression or isotropic compression to remove voids.

Hereinafter, the manufacturing method of the present invention will be described in detail for each step.

The manufacturing method of the present invention is an open void extending from one side or both side portions of the sculpture to the inside of the sculpture through 3D printing, and the open pore includes an open pore that does not penetrate the sculpture. And forming. That is, in the manufacturing method of the present invention, a sculpture of a three-dimensional structure is manufactured through 3D printing, but in the process of manufacturing the sculpture, open voids and measurements are made to extend from one or both sides of the sculpture to the inside of the sculpture. A void that is open to the outside of the mold is formed, and the void is formed so as not to penetrate the mold.

More specifically, when the open void is formed on one side of the model, the void is formed from one side of the model and extends in the direction of the other side, but is not open to the other side. A specific form is exemplarily illustrated in FIG. 2.

In addition, when the open voids are formed from both side portions of the sculpture, the voids are formed to extend into the side portions, but the voids formed by extending from both side portions are not connected to each other. The specific form is exemplarily illustrated in FIG. 3.

As a result, the open void formed in the manufacturing method of the present invention is a void where only one end of the void is open to the outside and the other end is not open.

In the present invention, by forming the pores as described above in the molded body, it is possible to remove unmelted powders inside the pores after the molding is completed, and there is an effect that the pore surface insulating coating is possible.

In addition, unlike a method of splicing individual sheets (for example, when splicing individual electrical steel sheets with an adhesive), the present invention is mechanically stable and has the advantage of high strength of the finally formed part.

The manufacturing method of the present invention includes the step of performing an insulating coating on the surface of the voids formed in the sculpture. At this time, the insulating coating can be performed in various ways, for example, a method of forming an insulating layer by drying or applying heat after immersing in a solution in which an inorganic salt/precursor or an organic insulating material is dissolved (dip coating), spray spraying the insulating solution. The coating may be performed by drying or applying heat to form an insulating layer (spray coating), or by exposing the sculpture to an oxidizing atmosphere to partially oxidize the surface to form an insulating layer.

The manufacturing method of the present invention includes the step of removing voids by performing one-way compression or isotropic compression after performing the insulating coating in the above step. If one-way compression or isotropic compression is performed immediately without the step of performing the insulating coating, only the formed voids disappear, so that the insulating layer cannot be formed in the molded body. Accordingly, after forming the voids, insulating coating is performed on the voids, and then compression is performed, so that an insulating layer can be formed in the molded body.

In addition, the manufacturing method of the present invention removes voids from the sculpture by performing one-way compression or isotropic compression after the insulating coating is performed, thereby removing the space unnecessarily present in the sculpture. Accordingly, there is an effect of improving the efficiency of the work performed by the sculpture.

On the other hand, it is preferable that the manufacturing method of the present invention further includes performing a heat treatment at 500 to 1300° C. before performing insulation coating on the sculpture in which open voids are formed through 3D printing. By performing heat treatment before coating the sculpture produced by the method of the present invention, there is an effect of improving the magnetic properties (permeability, iron loss) of the sculpture by growing the crystal grain size inside the sculpture and re-establishing the crystal orientation. . In general, when a sculpture is manufactured by the selective laser melting (SLM) method, crystal grains are formed very finely due to a high cooling rate, and thus the permeability decreases and the iron loss increases. The magnetic properties can be improved by growing crystal grains and re-establishing the grain direction by performing heat treatment after shaping.

In addition, at this time, when the heat treatment temperature is less than 500 ℃, there is a problem that the magnetic property improvement is not large because the temperature is low because atomic diffusion required for crystal grain growth and re-establishment occurs. If it exceeds 1300 ℃, the melting temperature of the alloy is approached. Therefore, there is a problem that causes the deformation of the sculpture.

Meanwhile, the insulating coating may be an organic coating or an inorganic coating, and an inorganic coating must be applied to form an insulating layer uniformly in a thickness of tens to hundreds of nanometers and to form an insulating layer with an overall uniform thickness on the pore surface. It is preferable to sequentially apply an inorganic coating and an organic coating in order to minimize empty space due to voids after molding and to improve adhesion.

According to the manufacturing method of the present invention, there is an advantage of being able to manufacture a sculpture including an insulating layer therein by a simple method.

In addition, the present invention provides a method of manufacturing a stator for an axial magnetic flux motor.

Unlike general radial flux motors, axial-flux motors have the direction of the magnetic field generated by the stator parallel to the shaft axis. Therefore, the area subjected to the force by the magnetic field is the stator electromagnet. It is given by the cross section of, and its value is the square of the radius multiplied by the Pi constant (π).

Figure 8 is a diagram showing the structural difference between the radial magnetic flux type motor and the axial magnet type motor. In the case of a radial magnetic flux type motor, the area subjected to force by the magnetic field is given by the circumferential area of the rotor cylinder, that is, the size of the diameter of the cylinder multiplied by the length of the cylinder. Therefore, when the axial length of the motor is short and the diameter is large, the axial magnetic flux type motor has a larger area to which the force is received than the radial magnetic flux type motor, so that the output is higher than that of the same volume (the power density is high).

In the case of the axial magnetic flux type motor, in the case of a general axial magnetic flux type motor, teeth of the stator exist and one side of the teeth is composed of a structure that is attached to and connected to a disc-shaped yoke. At this time, a magnetic field is generated only on the opposite side of the tooth that is not joined to the yoke, and the yoke prevents magnetic flux from being counted by connecting the magnetic flux between the teeth.

On the other hand, the yokeless type axial magnetic flux type motor, which is not a general axial flux type motor, removes the yoke that connects the teeth and places a rotor (permanent magnet) on the side that contacts the yoke, so that the rotor is It has a double rotor structure that exists on both sides. In this structure, the area in which the rotor is forced by the magnetic field is twice as high as that of the general type axial magnetic flux type motor, and thus the power density is higher in the same volume. 9 is a view showing the structure of a yokeless type axial magnetic flux type motor compared with a general radial magnetic flux type motor.

The present invention is specifically, through 3D printing, an open pore extending from one side or both side portions of the stator for an axial magnetic flux motor into the inside of the stator, the axis including an open pore in which the open pore does not penetrate the stator Forming a stator for a directional magnetic flux motor;

Performing an insulating coating on the surface of the pores; And

It provides a method of manufacturing a stator for an axial magnetic flux motor including an insulating layer including; step of removing voids by performing one-way compression or isotropic compression.

The manufacturing method of the present invention uses 3D printing to form a stator for an axial magnetic flux motor, but forms an open void extending from one or both side portions of the stator into the stator, and the open void formed at this time is the It is formed so as not to penetrate the stator. That is, when the open void is formed by extending from one side portion of the stator, it extends to the other side portion of the stator and is not opened, and when the open void is formed by extending from both side portions of the stator to the inside, the void is inside the side portion. The pores are formed to be extended to, but are formed so as not to be connected to each other. The specific shape is exemplarily shown in FIGS. 2 and 3.

The manufacturing method of the present invention has the effect of greatly reducing iron loss due to eddy currents of the stator by forming an insulating layer in the stator by forming open voids in the stator for the axial magnetic flux motor through the above steps. In addition, since the formed voids are open voids, unmelted powders inside the voids can be removed after the molding is completed, and there is an effect that insulating coating on the voids surface becomes possible. In addition, unlike a method of splicing individual sheets (for example, when splicing individual electrical steel sheets with an adhesive), the present invention is mechanically stable and has the advantage of high strength of the finally formed part.

The manufacturing method of the present invention includes the step of forming a stator for an axial magnetic flux motor including an open void by the above method, and then performing an insulating coating on the surface of the void. At this time, the insulating coating can be performed in various ways, for example, a method of forming an insulating layer by drying or applying heat after immersing in a solution in which an inorganic salt/precursor or an organic insulating material is dissolved (dip coating), spray spraying the insulating solution. The coating may be performed by drying or applying heat to form an insulating layer (spray coating), or by exposing the sculpture to an oxidizing atmosphere to partially oxidize the surface to form an insulating layer.

The manufacturing method of the present invention includes the step of removing voids by performing one-way compression or isotropic compression after performing the insulating coating in the above step. If one-way compression or isotropic compression is performed immediately without the step of performing the insulating coating, only the formed voids disappear, so that the insulating layer cannot be formed in the stator for the axial magnetic flux motor. Accordingly, after forming the voids, insulating coating is performed on the voids, and then compression is performed, so that an insulating layer can be formed in the stator for the axial magnetic flux motor.

In addition, the manufacturing method of the present invention removes voids in the stator for the axial magnetic flux motor by performing one-way compression or isotropic compression after the insulating coating is performed, thereby removing the space unnecessarily present in the stator, thereby saturating magnetic flux density. Can be prevented from deteriorating.

On the other hand, in the manufacturing method of the present invention, the stator for the axial magnetic flux motor to be formed is preferably formed to include a shoe in both the upper, lower, or upper and lower portions thereof. In the present invention, the shoe refers to a portion protruding in the same cross-sectional shape as the column around the top or bottom surface of the stator core column, and accordingly, the top and bottom surfaces of the stator have a structure that is wider than the cross-sectional area of the column part. I can have it. In order to generate a magnetic flux in the stator segment, an insulating coated copper wire is wound around the column, whereby the circumference of the stator segment including the winding becomes as large as the winding occupies. At this time, since the magnetic flux density exhibited by the winding itself is quite low, it does not affect the generation of power for driving the motor, and the stator cross-sectional area occupied by the winding becomes an unutilized area, which is the cause of lowering the power density of the motor. At this time, by forming shoes on the top and bottom of the stator, magnetic flux can be generated even in the cross-sectional area occupied by the winding, and the available magnetic flux generation area increases and the ratio of the area that does not generate magnetic flux decreases. There is an advantage in that the power density and torque density are improved.

The shoe formed on the stator for the axial magnetic flux motor is preferably formed to protrude outward based on the horizontal plane of the stator, and more preferably, it protrudes outward in all directions. The specific shape of the stator is exemplarily shown in FIGS. 7A to 7C. 7A is a structure in which no shoes are formed in the stator, and FIG. 7B is a structure in which shoes are formed in both the upper and lower sides of the stator, and the shoes are formed so as to protrude to the outside only in both side directions, not in all directions. The shoe is formed on both the upper and lower sides, and the shoe is formed so as to protrude outwardly in all directions, that is, both sides and front and rear.

When the shoe is formed by protruding outward in all directions based on the horizontal plane of the stator, magnetic flux may occur in the cross-sectional area occupied by the winding in all directions, and the available magnetic flux generation area increases and the ratio of the area that does not generate magnetic flux decreases. Therefore, as a result, there is an advantage that the power density and torque density of the motor are improved.

It is preferable that the width between adjacent insulating layers formed in the manufacturing method of the present invention is 0.05 mm to 0.5 mm. If the width is less than 0.05 mm, since the width is smaller than the size of the powder, there is a problem that the powder is melted and bonded undesirably between the voids, and if it exceeds 0.5 mm, the volume occupied by the stator is too large compared to the final part. There is this.

On the other hand, the manufacturing method of the present invention preferably further comprises the step of performing a heat treatment at 500 to 1300 °C before performing insulation coating on the stator for the axial magnetic flux motor in which the open air gap is formed through 3D printing. By performing heat treatment before coating the stator manufactured by the method of the present invention, there is an effect of improving permeability and reducing iron loss through grain growth and re-establishment.

In addition, at this time, when the heat treatment temperature is less than 500 ℃, there is a problem that the magnetic properties are not significantly improved because the temperature is low because atomic diffusion required for crystal grain growth and re-establishment occurs. If it exceeds 1300 ℃, the melting temperature of the alloy is approached. Therefore, there is a problem that causes the deformation of the sculpture.

According to the manufacturing method of the present invention, there is an advantage that it is possible to manufacture a stator for an axial magnetic flux motor including an insulating layer therein by a simple method, and also, by forming an insulating layer inside the stator in this manner, eddy current is generated. It has the effect of reducing the iron loss caused by and ultimately improving the efficiency of the axial magnetic flux motor.

Hereinafter, the present invention will be described in more detail through experimental examples. However, the following description is only intended to describe the present invention, and it is not expected that the scope of the present invention is limited and interpreted by the following description.

Confirmation of the effect of reducing iron loss according to the insulating layer

The following experiment was performed to confirm the effect of reducing iron loss due to the presence of an insulating layer in the stator.

Powder of Fe-6.5wt%Si composition having a size of 10 to 45 μm was used as the original powder, and the powder was continuously stacked using a concept laser's Mlab equipment, and only the selected area was dissolved with a laser to make a sculpture. The sculpture was manufactured using the SLM (Selective Laser Melting) technique. At this time, the laser spot size was 110 μm, the thickness of the powder layer was 25 μm, and the hatch space was 80 μm, and the laser power and scan speed were 90 W and 200 mm/s, respectively.

As for the structure without an insulating layer, a bulk-shaped sculpture without a donut-shaped insulating layer having an outer diameter of 35 mm, an inner diameter of 25 mm, and a height of 5 mm was prepared.

The structure with an insulating layer is a donut shape with an outer diameter of 35 mm, an inner diameter of 25 mm, and a height of 5 mm, and the shell thickness is 0.3 mm and the insulation layer thickness is 0.1 mm. The powder present in was removed and the shell surface was coated with paraffin wax to form an insulating layer.

The results of the experiment are shown in FIG. 4. According to FIG. 4, it can be seen that there is an effect of reducing iron loss as the insulating layer is actually formed inside the stator.

Confirmation of the effect of reducing iron loss according to the width between adjacent insulating layers

The following experiment was performed to confirm the difference in the effect of reducing iron loss according to the width between adjacent insulating layers formed on the stator.

A structure with an insulating layer is manufactured in a donut shape with an outer diameter of 35 mm, an inner diameter of 25 mm, and a height of 5 mm, and the width between the insulating layers is manufactured under three different conditions: 0.3 mm, 0.5 mm, and 1 mm. , The thickness of the insulating layer itself was applied equally to 0.1 mm to prepare a sculpture. The powder present in the pores was removed from the manufactured sculpture, and the shell surface was coated with paraffin wax to form an insulating layer. In addition, the method and conditions for manufacturing the sculpture including the insulating layer are the same as in Experimental Example 1.

The results of the experiment are shown in FIG. 5. According to FIG. 5, it can be seen that the narrower the width between the insulating layers, the greater the effect of reducing iron loss, and the width between the insulating layers becomes 0.5 mm, and even if the width is narrower, the effect of reducing iron loss is significantly improved. You can see that it doesn't work.

Confirmation of the effect of reducing iron loss by heat treatment

The following experiment was performed to confirm the effect of performing heat treatment before coating the pores formed in the stator.

A structure with an insulating layer is manufactured in a donut shape with an outer diameter of 35 mm, an inner diameter of 25 mm, and a height of 5 mm, and the width between the insulating layers is manufactured under three different conditions: 0.3 mm, 0.5 mm, and 1 mm. , The thickness of the insulating layer itself was applied equally to 0.1 mm to prepare a sculpture. In the order of removing the powder existing in the pores from the manufactured sculpture, raising the temperature ^{to 1000 o} ^{C at a heating rate of 5 o} C/min in an argon atmosphere using a tube furnace, maintaining the temperature for 2 hours, and then cooling by furnace. Heat treatment was performed. In addition, the method and conditions for manufacturing the sculpture including the insulating layer are the same as in Experimental Example 1.

The results of the experiment are shown in FIG. 6. According to FIG. 6, it can be seen that the effect of reducing iron loss is greater when the heat treatment is performed than when the heat treatment is not performed. In addition, before the heat treatment, there is little difference in the effect of reducing the iron loss when the width between the insulating layers is 0.5 mm and the width between the insulating layers is 0.3 mm. In the case of, it can be seen that the effect of reducing the iron loss is higher.

Confirmation of changes in density and surface roughness according to heat treatment

The following experiment was performed to confirm the change in density and surface roughness according to the heat treatment temperature.

Based on the SLM process, it was manufactured in the form of a rectangular parallelepiped sheet having a length of 40 mm, a height of 10 mm, and a width of 0.5 mm. ^{The order of heating the manufactured object to 1000 o} C, 1100 ^o C, and 1200 ^o ^{C at a heating rate of 5 o} C/min in an argon atmosphere using a tube furnace, and then maintaining the temperature for 2 hours and then cooling by furnace. A total of 4 specimens were prepared, including specimens not subjected to heat treatment by performing heat treatment with furnace. The cross section of the prepared four specimens was photographed with an optical microscope, and surface roughness was measured by calculating the standard deviation relative to the center straight line of the edge of the cross section using an image analysis program (Image J). In addition, by measuring the weight of the sculpture in air and in water, the density was measured based on the Archimedes principle, and the relative density was shown in FIG. 10 by comparing it with the theoretical density.

According to FIG. 10, it can be seen that as the heat treatment temperature increases, the relative density of the specimen increases, and through this, it can be seen that the key hole pores generated during the lamination molding decrease with the increase of the heat treatment temperature. In addition, it can be seen from FIG. 10 that the surface roughness decreases as the heat treatment temperature increases. It can be seen that it is desirable to increase the heat treatment temperature because the relative density improvement and the reduction of the surface roughness improve the final filling rate of the sculpture including the insulating layer and have a positive effect on the improvement of the saturation magnetic flux density of the sculpture.

Checking the effect of iron loss reduction effect according to the heat treatment temperature

The following experiment was performed to determine how the iron loss reduction effect was affected by the heat treatment temperature.

Based on the SLM process, it was manufactured in the form of a rectangular parallelepiped sheet having a length of 40 mm, a height of 10 mm, and a width of 0.5 mm. Using a tube furnace, the molded body was heated up ^{to 1000 o} C, 1100 ^o C, and 1200 ^o ^{C at a heating rate of 5 o} C/min in an argon atmosphere, and then kept at the temperature for 2 hours, followed by furnace cooling. A total of four specimens were prepared, including specimens not subjected to heat treatment by performing heat treatment. For a total of four manufactured specimens, the degree of iron loss was measured by single sheet measurement using a BH analyzer (IWATSU SY-8219), and the measured iron loss result when the magnetic flux density was fixed at 1T and the frequency was changed from 50 Hz to 1 kHz. Is shown in FIG. 11. According to FIG. 11, it can be seen that the iron loss reduction effect increases as the heat treatment temperature increases. This is because the residual stress is resolved by the heat treatment and the coercive force decreases as the crystal grains of the sculpture grow and become coarse. 13A to 13D show cross-sectional SEM photographs according to the heat treatment conditions of the sculpture, showing that crystal grains grow as the heat treatment temperature increases, and the average grain size immediately after shaping was 10.2 μm, but after 2 hours heat treatment at ^{1200 o C.} The grain size was grown to 154 μm.

Production of high-density sculptures through isotropic compression

Based on the SLM process, a sheet-shaped sculpture of a rectangular parallelepiped having a length of 90 mm, a height of 10 mm, and a width of 0.5 mm is manufactured, and the sheet is divided into 1, 2, 3, 4, 5, 6 and 7 layers. , And 11 layers are formed to be aligned side by side, and each sheet is connected to each other at the ends to prepare a stacked sculpture to form a single sculpture, and DC BH Loop Tracer (Magnet physik, Remagraph C-500) is used for this. By measuring the BH Loop under the condition of the applied magnetic field -60 to 60 kA/m, the highest magnetization value was derived and the saturation magnetization value was measured, and the results are shown in FIGS. 12A to 12C.

According to FIGS. 12A to 12C, it can be seen that even if the sculpture is stacked up to 11 layers, the saturation magnetization value is maintained at about 1.68 T, and a high-density sculpture can be manufactured through isotropic compression.

Claims

Forming an open void extending from one side or both side portions of the sculpture to the inside of the sculpture through 3D printing, and including an open pore in which the open pore does not penetrate the sculpture;

Performing an insulating coating on the surface of the pores; And

A method of manufacturing a sculpture including an insulating layer comprising a step of removing voids by performing one-way compression or isotropic compression.
The method of claim 1, further comprising performing a heat treatment at 500 to 1300° C. before performing the insulating coating on the formed sculpture.
The method of claim 1, wherein the insulating coating is an organic coating or an inorganic coating.
Through 3D printing, the stator for an axial magnetic flux motor is an open gap extending into the stator from one side or both sides of the stator for the axial flux motor, and the open gap does not penetrate the stator. Forming a;

Performing an insulating coating on the surface of the pores; And

A method of manufacturing a stator for an axial magnetic flux motor comprising an insulating layer comprising; removing voids by performing one-way compression or isotropic compression.
[5] The method of claim 4, wherein the stator for the axial magnetic flux motor is formed to include shoes in both upper, lower, or upper and lower portions thereof.
The method of claim 5, wherein the shoe is formed to protrude outward based on a horizontal plane of the stator.
The method of claim 6, wherein the shoe is formed to protrude outwardly in all directions with respect to the horizontal plane of the stator.
The method of claim 4, wherein the width between the adjacent insulating layers is 0.05 mm to 5 mm.
The method of claim 4, wherein the formed stator for an axial magnetic flux motor further comprises performing a heat treatment at 500 to 1300 °C before performing the coating. Manufacturing method.
The method of claim 4, wherein the insulating coating is performed with an organic coating or an inorganic coating.