JPH0219612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for induction heating a laminated iron core.

Conventionally, there is an induction heating device for a laminated iron core as shown in FIG. First, the principle of heating in this type of apparatus will be explained with reference to FIG. 2, which shows the main part of FIG. 1.

When an alternating current is passed through the heating coil 1, the magnetic flux φ changes, and an induced current is generated concentrated at a certain depth from the outer peripheral surface of the laminated iron core 2. The thickness of the layer where this current is concentrated is called the current penetration depth, and if this is expressed in δ (cm), it is given by the following equation.

Here, ρ: Specific resistance (Ωcm) of the heated object (laminated core) μ: Magnetic permeability of the heated object (laminated core) f: Frequency of alternating current For iron core material at room temperature, ρ = 10 × 10 ^-6 Ωcm, μ =100
The induced current flows in a concentrated manner within the depth δ given by the above equation based on the frequency of the alternating current, generating heat. The specific resistance near the outer surface of the laminated core increases as the temperature rises, and at the A2 transformation point (approximately 750℃), ρ = 1000
×10 ^-6 Ωcm, while the magnetic permeability is μ at the A2 transformation point.
=1.

As a result, the induced current flows through the part of the laminated core that enters inside from the outer peripheral surface, generating heat in that part, and the heating layer gradually moves inside the laminated core.As a result, the entire laminated core is heated. Ru.

Now, in the device shown in FIG. 1, a heating coil 1 is placed vertically, and a heated laminated core is sequentially taken out from below by a handling device consisting of a clamper cylinder 3, a horizontal push cylinder 4, and a laminated core receiving cylinder 5. ing. Therefore, due to the patching process, changes in the state of the laminated core (at room temperature and
(High temperature) causes large fluctuations in the coil load, which causes fluctuations in the power factor of the power supply.

In order to maintain a good power factor, it is necessary to change the capacitance of a capacitor in the electric circuit, which complicates control. On the other hand, if the deterioration of the power factor is ignored, there is a problem in that the reactive current increases. Also, because one side of the laminated core is lifted by the magnetic force, a presser weight is required.

In addition, as other conventional devices of this type,
As shown in the figure, the heating coil 6 is placed horizontally, the laminated iron core is pushed into the guide 8 around which the heating coil 6 is wound by a pusher cylinder 7, and the extruded laminated iron core is carried out by a conveyor 9. There is something I did.

Although this device is also a batch type, it is close to a continuous type, so it is easier to control the power supply than in the case of the above-mentioned device. However, the guide 8 must be strong enough to prevent the laminated core from turning due to magnetic force, and must also serve as a guard to prevent the laminated core from hitting the heating coil 6. The structure is difficult, and the guide 8 and conveyor 9 It is also difficult to connect the parts.
Furthermore, if the laminated core is thin, care must be taken to prevent it from tipping over during transfer.

Similarly, as a conventional example in which a heating coil is placed horizontally, the one described in Japanese Unexamined Patent Publication No. 47-40102 is known. This annealing method involves arranging the motor cores in a cylindrical row in the axial direction, continuously inserting them into a heating furnace with induction coils wrapped around the cylindrical furnace wall, and rapidly heating them using induction heating at commercial frequencies. It was designed to do so. However, in the annealing method described in JP-A-47-40102, the motor core is conveyed in the same direction as its thickness direction (axial direction), so the motor core is heated in the same way as described above. The heating is carried out by sequentially moving the heating layer from the outer periphery to the inner periphery of the iron core, and as a result, there is a problem that the frequency of the alternating current is limited due to the heating depth. It was hot.

The above conventional induction heating devices for laminated iron cores all carry the laminated iron core into a heating coil, but as a device for induction heating other materials to be heated, as shown in Fig. 4, Heated material (flat plate) 1
There is one in which an inductor 11 is installed parallel to the heated surface 10a of the heater.

This device uses the same heating principle, and changes the magnetic flux φ by passing an alternating current through the inductor 11 (the current flows alternately from the front to the paper and from the paper to the front), and generates an induced current on the surface of the flat plate. , heat is generated due to the specific resistance of the flat plate 10.

When the flat plate 10 is moved in the horizontal direction, the flat plate surface is heated continuously and uniformly. This device is used in conjunction with a water cooling device for induction hardening. If the flat plate 10 is fixed, the heat generating layer will gradually move deeper, but this will be inefficient.

When this type of device is applied to heating a laminated iron core, a configuration as shown in FIG. 5 can be considered. However, since the laminated iron core 12 is a stack of thin veneers (thickness: 0.35 mm to 0.64 mm) with insulation between layers, eddy currents are generated in each veneer and do not reach a large value. Since heat is generated by this induced eddy current, the amount of heat generated is small.

Therefore, although this type of device can heat only the vicinity of the inductor 11, it is impossible to heat the entire laminated core.

The present invention has been made in view of the above-mentioned circumstances, and is capable of efficiently performing induction heating while continuously moving the laminated iron core, and which is not limited by the frequency of alternating current. An object of the present invention is to provide a heating method and apparatus.

According to this invention, a pair of heating inductors are arranged opposite to each other, and an alternating current is passed through the coils of the pair of heating inductors so that the polarities of the opposing heating inductors are opposite to each other. The direction of the magnetic flux generated between the pair of heating inductors is made to match the thickness direction of the laminated core, and the laminated core is continuously inserted between the pair of heating inductors from a direction perpendicular to the thickness direction. The laminated core is conveyed, and the entire laminated core is induction-heated while sequentially moving the induction-heated portion of the laminated core by the heating inductor.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 6a and 6b are a front view and a side view, respectively, showing the relationship between the heating inductor and the laminated core according to the present invention. A pair of heating inductors 20a, 20
b are arranged opposite to each other, and have a rectangular cross-sectional shape, the long side of which is slightly longer than the diameter of the laminated core 21, and the short side of which is sufficiently shorter than the long side (see Fig. 6b). .

By passing an alternating current through the coils of the heating inductors 20a and 20b, magnetic poles are generated. The polarity of the inductor and the direction of the magnetic flux φ shown in FIG. 6a are reversed at the next instant. Furthermore, the laminated core 21 is arranged between the heating inductors so that the direction of the magnetic flux φ generated between the pair of heating inductors 20a and 20b matches the thickness direction of the laminated core 21 (see FIG. a) and in a direction perpendicular to the thickness direction of the laminated core 21, that is, in the direction of arrow A (see FIG. 6b).

Next, the principle of heating according to the present invention will be explained with reference to FIG. By passing an alternating current through the coil of the inductor, a magnetic flux φ is generated between the inductors, and a vortex is generated in each core (single plate) 21a of the laminated core 21 in a direction perpendicular to the magnetic flux, that is, in the width direction of the single plate 21a. A current I is induced and each core in that section is activated.

By continuously moving the laminated core 21, the entire laminated core 21 is induction heated while the induction heating portions are sequentially moved. Furthermore, even if the iron core is partially heated, when it reaches the A2 transformation point (near 750℃), the magnetic permeability becomes μ = 1,
The heated portion gradually shifts toward μ≫1 without being overheated.

That is, while the conventional technology moves the heating layer sequentially from the outer periphery to the inside of the laminated core, the present invention heats a part of the laminated core while continuously moving the laminated core, thereby gradually applying the heating layer to the entire laminated core. It is something.

Therefore, in the prior art, the frequency of the alternating current was restricted due to the relationship with the heating depth, but in the case of the present invention, the most efficient frequency can be applied. Furthermore, since the laminated core is moved continuously, the integrated work of insertion, heating, soaking, cooling, and removal can be easily performed.

Next, the structure of the device of the present invention will be explained.

FIG. 8 is a front sectional view showing an embodiment of the heating inductor according to the present invention. The core 25 is constructed by bundling wires 26 into a substantially C-shape and further surrounding it with a copper film 27. As an example of the wire rod 26,
Use piano wire (approximately 0.01 mm in diameter) that has been parkerized. Alternatively, a small diameter copper pipe (not shown) for water cooling may be inserted into the core 25.

On the other hand, a pair of opposing heating inductors 28a, 2
8b is constructed by surrounding both ends of the core 25 with coils (square copper tubes) 29 and 30, respectively (see FIG. 9). In addition, the coils 29, 3
It is also possible to cool the coils 29, 30 by flowing water through the coils.

Then, as shown in FIG. 9, by connecting the coils 29 and 30 to the high frequency power source 31, the polarities of the facing surfaces of the opposing heating inductors 28a and 28b are made to be opposite to each other.

FIG. 10 is a front sectional view showing another embodiment of the heating inductor according to the present invention. The core 35 is constructed by laminating approximately C-shaped thin plates 36 and further surrounding them with a copper film 37. As an example of the thin plate material 36, a silicon steel plate (about 0.1 mm thick) coated with an insulation coating is used.

On the other hand, a pair of opposing heating inductors 38a, 3
8b is constructed by surrounding both ends of the core 35 with coils (square copper tubes) 39 and 40, respectively (see FIG. 11).

As described above, the pair of heating inductors 28a,
By configuring 28b, 38a, and 38b, the magnetic path generated in the inductor can be closed by the core, and leakage magnetic flux can be reduced. Furthermore, by surrounding the core with a copper film, leakage is doubly prevented. Note that the former heating inductors 28a and 28b are used when the frequency is relatively high, and the latter heating inductors 38a and 38
b is preferably used when the frequency is relatively low.

Next, an example of a conveying means for carrying a laminated core in and out between a pair of heating inductors will be described.

As shown in FIG. 12, this conveyance means includes a conveyor in which a conveyor belt 51 passes between a pair of heating inductors 50a and 50b,
1, a case body 52 is attached, and a case 54 accommodates a laminated core 55.

The case 54 is made of high temperature material (approximately 900℃).
Use a material that is strong and has electrical insulation properties that are not affected by magnetic fields. For example, hard porcelain can be used. In addition, the inner width of the case is made to be the same as the height of the laminated core, or the inner width of the case is made with a margin for flexibility, and a distance piece is used.

By housing the laminated core 55 in this case 54, the laminated core does not rotate due to magnetism even when the core passes through a high-frequency magnetic field, and the core and coil can be electrically insulated. .

Further, as shown in FIG. 13, the case 54 can be kept airtight by providing a sand seal (for example, asbestos powder) 56 between the case body 52 and the case lid 53. Further, the case lid 53 is provided with a gas supply hole 57 with a lid and a gas vent hole 58 with a non-returnable gas vent.

Therefore, when heating in an atmosphere of a gas heavier than air (for example, carbon dioxide gas), the laminated core is housed in this case 54 and the covered gas supply hole 57 is
The above gas can be injected from.

14 and 15 show another embodiment of the case, in which a case bottom plate 62 is attached to a conveyor belt 61, a sand seal 66 is interposed on the case bottom plate 62, and a case main body 63 is attached to the case bottom plate 62. It is designed to be covered with. A gas supply hole 67 with a lid is provided in the upper part of the case body 63 of the case 64, and a gas vent hole 68 with a non-returnable gas vent is provided in the case bottom plate 62.

Therefore, when heating in an atmosphere of a gas lighter than air (for example, nitrogen gas), the laminated core is housed in this case 64 and the covered gas supply hole 67 is
The above gas can be injected from. In the case of _N2 atmosphere annealing, it has been difficult to block the air (to prevent air from entering the furnace) when inserting and extracting the laminated core into the furnace, especially when the laminated core has uneven surfaces. is difficult, but it becomes extremely easy by using the above case.

As explained above, according to the present invention, the direction of the magnetic flux generated between a pair of heating inductors is made to match the thickness direction of the laminated iron core, and the laminated iron is The laminated core is continuously conveyed between a pair of heating inductors, and the entire laminated core is induction heated while the induction heating portion of the laminated core is sequentially transferred by the heating inductor. It can be done efficiently.
Furthermore, since there is no restriction on the frequency of the alternating current, the most efficient frequency can be applied. Furthermore, since the laminated core is moved continuously, it is possible to easily perform the integrated operations of insertion, heating, soaking, cooling, and removal.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an example of a conventional laminated core induction heating device, Fig. 2 a and b are a front view and a plan view showing the main parts of Fig. 1, respectively, and Fig. 3 is a conventional laminated core. A schematic configuration diagram showing another example of the induction heating device, FIG. 4 is a diagram in which the heating inductor and the heated surface of the heated material are installed parallel to each other, and FIG. 5 is a schematic diagram showing another example of the induction heating device in FIG. Diagram when laminated core is applied,
6a and 6b are a front view and a side view showing the relationship between a pair of heating inductors and a laminated core, respectively, according to the present invention, and FIG. 7 is a diagram used to explain the heating principle according to the present invention, FIG. 8 is a front sectional view showing one embodiment of the heating inductor according to the present invention, FIG. 9 is a perspective view of the heating inductor coil shown in FIG. 8 in a state where it is connected to a high frequency power source, and FIG. 10 11 is a front sectional view showing another embodiment of the heating inductor according to the present invention, FIG. 11 is a perspective view of the heating inductor shown in FIG. 10, and FIGS. 12 a and b are respectively conveying means according to the present invention. 13 is an enlarged view of the main part of FIG. 12b, and FIGS. 14a and 14b are main parts of another embodiment of the conveyance means according to the present invention. A side sectional view and a front sectional view, and FIG. 15 is an enlarged view of the main part of FIG. 14b. 20a, 20b, 28a, 28b, 38a, 3
8b, 50a, 50b... heating inductor, 21,
55... Laminated iron core, 25, 35... Core, 26...
...Wire rod, 27,37...Copper film, 29,30,3
9, 40...Coil, 31...High frequency power supply, 36
... Thin plate material, 51, 61 ... Conveyor belt, 5
2, 63...Case body, 53...Case lid,
54, 64... Case, 56, 66... Sand seal, 57, 67... Gas supply hole with lid, 58,
68... Gas vent hole with non-returnable gas, 62... Case bottom plate.

Claims (1)

[Claims] 1 A pair of heating inductors are arranged opposite each other, and an alternating current is passed through the coils of the pair of heating inductors so that the polarities of the opposing heating inductors are opposite to each other. , by aligning the direction of the magnetic flux generated between the pair of heating inductors with the thickness direction of the laminated core, the laminated core is continuously connected between the pair of heating inductors from a direction perpendicular to the thickness direction. A method for induction heating a laminated core, the method comprising: transporting the laminated core to a heating inductor, and inductively heating the entire laminated core while sequentially moving the induction heating portion of the laminated core by the heating inductor. 2 a pair of heating inductors; current supply means for supplying an alternating current to the coils of the pair of heating inductors so that the polarities of the pair of heating inductors are opposite to each other; A laminated iron core in which the direction of magnetic flux generated between the inductors matches the thickness direction of the laminated iron core, and the laminated iron core is continuously conveyed between the pair of heating inductors from a direction perpendicular to the thickness direction. An induction heating device for a laminated iron core, comprising a conveying means. 3. The laminated iron core induction heating device according to claim 2, wherein the pair of heating inductors comprises a substantially C-shaped core and a coil wound around both ends of the core. 4. The induction heating device for a laminated iron core according to claim 3, wherein the substantially C-shaped core is formed by bundling wires into a substantially C-shape and surrounding it with a copper film. 5. The induction heating device for a laminated iron core according to claim 4, wherein the wire is a piano wire having a diameter of about 0.01 mm and subjected to a parkerizing treatment. 6. The laminated iron core according to claim 3, wherein the substantially C-shaped core is formed by laminating substantially C-shaped silicon steel plates with a thickness of about 0.1 mm with an insulating coating, and surrounding this with a steel film. Induction heating device. 7. The laminated iron core according to claim 2, wherein the conveying means comprises a conveyor on which a conveyor belt passes between a pair of heating inductors, and a case for storing the laminated iron core attached to the conveyor belt. Induction heating device. 8. The laminated iron core induction heating device according to claim 7, wherein the case is made of hard porcelain. 9. The laminated iron core induction heating device according to claim 7, wherein the case is formed with a gas supply hole and a gas vent hole.