JP2019094558A - Annealing device of motor core and annealing method of motor core - Google Patents

Abstract

To provide a method of carrying out a step of annealing for removing strain generated when fixing by punching a magnetic steel sheet constituting a motor core, caulking or screwing, or welding in a short time.SOLUTION: An annealing device of annealing a motor core has any one or both of a cyclic outside induction coil 20 having a thickness in an axial direction smaller than the motor core C arranged coaxially with the motor core C on the outside of a motor core C to be annealed, and, a cyclic inside induction coil 21 having a thickness in the axial direction smaller than the motor core C arranged coaxially with the motor core C on the inside of a motor core C, and, further an AC power supply 30 for inputting an AC current to the outside induction coil 20 and/or inside induction coil 21, and a moving mechanism for varying a relative position in the axial direction between the outside induction coil 20 and/or inside induction coil 21 and the motor core C.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an annealing apparatus for performing punching and bending of a motor core made of non-oriented electrical steel sheet, annealing for removing distortion due to welding and the like, and an annealing method for a motor core using the annealing apparatus.

A motor core has a rotor core fixed and rotating around a motor rotation shaft (output shaft, output shaft) and a motor case coaxially fixed to the motor case, and when the motor is used There is a stator (stator) core that generates a rotational force in the rotor by the interaction of the electromagnetic force between the outer periphery of the rotor and the inner periphery of the rotor, but both may be generically referred to as a motor core.
A motor core (iron core) manufactured by laminating a large number of materials punched into a predetermined shape from non-oriented electrical steel sheets and fixing them by caulking, screwing, welding, etc. Since the iron loss is aggravated by the strain generated at the time of fixing by fastening, welding or the like, heating is usually performed by a continuous or batch annealing furnace for a predetermined time in order to remove the strain. The annealing furnace is heated by, for example, radiant heat from an electric heater or the like and conductive heat from an atmosphere gas (see the background art of Patent Document 1).

  Further, in recent years, as an annealing method different from radiation heating such as an electric heater, a method using induction heating as disclosed in, for example, Patent Documents 1 to 3 is known. In the methods disclosed in Patent Documents 1 to 3, not only annealing of the entire motor core but also, for example, "partial annealing around a slot (iron core groove) of the inner periphery of the stator core" of Patent Document 1 The heating is performed by an induction coil provided outside the motor core.

Japanese Patent Application Laid-Open No. 62-272843 Unexamined-Japanese-Patent No. 2003-342637 Japanese Patent Application Laid-Open No. 58-104125

  By the way, in recent years, in the production of a motor core of a drive motor or a generator such as a hybrid vehicle (HEV) or an electric vehicle (EV) where high productivity is required, shortening of annealing time is required. However, in radiation heating using an electric heater or the like, there is a limit to shortening the heating time. Further, in the short-time annealing by radiation heating, there is a problem that the temperature distribution is not uniform in the height direction of the motor core and at the back and front of the teeth portion where the distortion at the time of punching is particularly large.

  Moreover, the annealing apparatus for a motor core by induction heating disclosed in Patent Documents 1 to 3 has an induction coil on the outside of the motor core even in the case of annealing of a stator core in which the strain to be annealed is mainly formed on the inner circumferential side. Since it takes time for heating due to the arrangement, there is a limit to shortening the time for annealing.

  The present invention has been made in view of such a point, and annealing of a motor core for removing distortion generated during punching of a magnetic steel sheet constituting the motor core, or during fixation by caulking, screwing, welding or the like The purpose is to do in a short time.

  The present invention for achieving the above object is an apparatus for laminating and annealing one or a plurality of motor cores formed by laminating electromagnetic steel sheets after punching, and the motor core having one or more laminated layers. (Hereinafter, referred to simply as "a plurality of motor cores to be annealed.") It is disposed concentrically with the motor core to be annealed, and the lamination direction of the electromagnetic steel sheets from the motor core to be annealed (coincident with the axial direction of the motor core). And an annular outer induction coil having a small thickness in the axial direction, and concentrically disposed inward of the annealed motor core with the annealed motor core, and the axial thickness of the annealed motor core is greater than that of the annealed motor core. And / or an annular inner induction coil, and applying alternating current to the outer induction coil and / or the inner induction coil That an AC power source, is characterized by having a moving mechanism for changing the axial direction of the relative position of the outer induction coil and / or the inner induction coil and the object to be annealed motor core.

  According to the present invention, the punched electromagnetic steel sheet which is laminated and fixed by caulking, screwing, welding or the like and becomes a motor core shape is heated by induction heating according to the application, and punching of the electromagnetic steel sheet for motor core Annealing can be performed in a short period of time to remove the strain that has occurred during bonding, caulking, screwing, welding and the like. In addition, since the axial thickness of the outer induction coil and the inner induction coil is smaller than that of the motor core to be annealed, the power supply capacity of the AC power supply can be reduced. The motor core targeted by the present invention includes both a stator core (stator) and a rotor core (rotor).

  Furthermore, for example, by adjusting the frequency of the alternating current to be applied, the penetration depth of the eddy current is adjusted by the skin effect, or the magnetic flux generated by the outer induction coil and the inner induction coil is controlled to heat the portion to be heated. Since it can be adjusted, annealing can be performed under optimum conditions even at locations where control of the temperature distribution is difficult in radiant heating, such as the back and front of the teeth portion (see FIG. 3 etc.), for example.

  The moving mechanism may move the to-be-annealed motor core in an axial direction. For example, in the case where the to-be-annealed motor core is configured to be mounted on the horizontal mounting plate so that the axial direction is in the vertical direction, the mounting plate may be moved in the axial direction .

  The moving mechanism may move the induction coil at least on the side opposite to the side on which the slot of the motor core to be annealed is formed in the axial direction.

  When both the outer induction coil and the inner induction coil are included, the moving mechanism may move the outer induction coil and the inner induction coil in synchronization in the axial direction.

  When having both the outer induction coil and the inner induction coil, the AC power supply generates the AC magnetic flux in the same direction in the region surrounded by the outer induction coil and the inner induction coil. An alternating current may be applied to the coil and the inner induction coil,

  When having both the outer induction coil and the inner induction coil, the outer induction coil and the inner induction coil may be connected to form a circuit in series with the AC power supply.

  10 kHz or more may be sufficient as the frequency of the alternating current applied by the said alternating current power supply.

  You may further have the partition for annealing atmosphere adjustment which accommodates the said to-be-annealed motor core inside, and the heat insulating material which covers the outward or inner side of the said partition.

  You may have a cooling device which cools the heating part of the to-be-annealed motor core heated by the said outer side induction coil and / or the said inner side induction coil.

  You may have the rotational drive mechanism which relatively rotates the said to-be-annealed motor core, the said outer side induction coil, and / or the said inner side induction coil.

The present invention according to another aspect is an annealing method of a motor core for removing a strain introduced on an outer peripheral surface and / or an inner peripheral surface of the motor core to be annealed using the annealing apparatus for the motor core, The annealing target motor core is inductively heated by the alternating current of the frequency f of the AC power supply determined to be the penetration depth δ in the following formula (1) according to the depth, and the outer peripheral surface of the annealing target motor core and / or Alternatively, the inner peripheral surface is heated to 750 to 850 ° C.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: penetration depth of eddy current causing induction heating :: volume resistivity μ of the motor core to be annealed: permeability of the motor core to be annealed f: frequency of alternating current applied by the AC power supply.

  The temperature of the outer peripheral surface and / or the inner peripheral surface may be raised to 750 to 850 ° C. while suppressing the temperature inside the annealed motor core to 500 ° C. or less.

  According to the present invention, the motor core can be annealed in a short time to remove the strain generated during punching of the magnetic steel sheet constituting the motor core, or during fixation by caulking, screwing, welding or the like. .

It is a longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 1st Embodiment of this invention. It is a perspective view which shows the state which has arrange | positioned the to-be-annealed motor core between an outer induction coil and an inner induction coil. It is the top view which looked at the motor core from the through-hole direction, and is the partial top view which cut out a part of circumferential direction. It is explanatory drawing of the inner side mounting stand concerning the 1st Embodiment of this invention, an intermediate mounting stand, and an outer side mounting stand. It is explanatory drawing which cut out a part of motor core and was seen diagonally. It is explanatory drawing which cut out a part of motor core and was seen diagonally. It is explanatory drawing which cut out a part of motor core and was seen diagonally. It is explanatory drawing which cut out a part of motor core and was seen diagonally. It is a longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 2nd Embodiment of this invention. It is explanatory drawing of the rotation drive part with which the annealing apparatus concerning 2nd Embodiment of this invention is provided. It is a longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 3rd Embodiment of this invention. It is a figure for demonstrating the annealing treatment using the annealing apparatus concerning 3rd Embodiment, Comprising: It is a figure which shows the mode in the partition of an annealing apparatus. It is a figure for demonstrating the annealing treatment using the annealing apparatus concerning 3rd Embodiment, Comprising: It is a figure which shows the mode in the partition of an annealing apparatus. It is a longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 4th Embodiment of this invention. It is a figure which shows the difference of the temperature history by the site | part of the to-be-annealed motor core annealed by the annealing apparatus concerning 4th Embodiment of this invention. It is a graph which shows the relationship between the frequency of the alternating current, the heat generation density, and the depth from the surface.

First Embodiment
Hereinafter, a first embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view showing the outline of the configuration of the annealing apparatus according to the present embodiment. FIG. 2 shows a motor core to be annealed between an outer induction coil and an inner induction coil (a motor core assembly in which one or a plurality of motor cores to be annealed are aligned in the axial direction) is an area occupied by the annealed motor core For convenience of the description of the device, there is a case where it is treated as if the motor core to be annealed is present in the region), and it is a schematic perspective view showing a state in which it is disposed. FIG. 3 is a view schematically showing a part of a general motor core (stator core) in a partial top view. The motor core includes a rotor core on the motor rotation shaft side and a stator core on the outer side thereof. In the following description, the explanation will be mainly made by taking the annealing of the stator core as an example. It is not necessary to distinguish between the two as it can be applied to annealing, and the term of motor core is used to generically refer to both. Further, in the present specification and the drawings, in elements having substantially the same functional configuration, the same reference numerals will be appended to omit redundant description.

  The annealing apparatus 1 shown in FIG. 1 is a lamination of a plurality of raw materials punched into a predetermined shape from a non-oriented electrical steel sheet, and annealing of a motor core C manufactured by sticking, caulking, screwing, welding, etc. It is intended to remove the strain (hereinafter sometimes referred to as "strain due to punching or the like") generated at the time of fixation during welding, caulking, screwing, etc. The annealing apparatus 1 includes a heating induction coil 10, a partition 11 for annealing atmosphere adjustment that surrounds the outside of the heating induction coil 10, and a heat insulator 12 that surrounds the outside of the partition 11.

  The partition 11 has, for example, a substantially cylindrical lid 11a whose lower surface is open and a bottomed container 11b whose upper surface is open, and the inside of the partition 11 can be kept airtight by, for example, water sealing. . A gas supply pipe 13 for supplying an atmosphere gas such as nitrogen to the inside of the partition 11 is connected to the lid 11 a.

  The axial direction of the outer induction coil, the inner induction coil, and the annealed motor core in the container portion 11b (Z direction in FIG. 1. The axial directions of the outer induction coil, the inner induction coil, and the annealed motor core coincide with each other). As an example of the moving mechanism which changes relative position, the below-mentioned inner mounting base 14, the intermediate mounting base 15, and the outer mounting base 16 are provided. Although the details of these mounting bases 14 to 16 will be described later, among these mounting bases 14 to 16, an intermediate mounting base (hereinafter also referred to as a motor core mounting base) 15 on which the motor core C to be annealed is mounted is axial ( The to-be-annealed motor core C is configured to be movable along the Z direction in FIG.

  If the heat insulating material 12 is provided, the thermal efficiency of the annealing device of the motor core can be enhanced, which is preferable. The material, form, etc. of the heat insulating material 12 are not particularly limited, and various materials such as known inorganic materials such as calcium silicate and alumina, such as cotton, cloth, plate, foam, etc. It can be processed into the following form. Moreover, although the example arrange | positioned so that the outer side of the partition 11 may be enclosed as an installation position of the heat insulating material 12 is shown in FIG. 1, it does not restrict to this, The to-be-annealed motor core C, the outer induction coil 20, and a partition If it is a position which does not interfere with 11 grade | etc. ,, it may be arrange | positioned so that the inner side of the partition 11 may be covered.

  For example, as shown in FIG. 2, the heating induction coil 10 has an annular outer induction coil 20 disposed concentrically with the annealing motor core C outside the annealing motor core C and the inside of the annealing motor core C. And the annular inner induction coil 21 disposed concentrically with the motor core C to be annealed. The motor core C here is a stator core and is formed in a cylindrical shape, and as shown in FIG. 3, slots (iron core grooves) Cc formed at equal intervals on the inner peripheral portion of the motor core C. And a tooth (teeth) portion Ca which is a partition wall provided between the slots Cc, and a back yoke (back yoke, successor iron) portion Cb connecting the outer peripheral end of the tooth portion Ca. Further, the slot Cc is formed over the entire length of the motor core C in the axial direction (the Z direction in FIG. 2. This corresponds to the stacking direction of the magnetic steel sheets).

It returns to the explanation of FIG. 1 and FIG.
Both the outer induction coil 20 and the inner induction coil 21 are formed to have a smaller thickness in the axial direction than the motor core C to be annealed, for example, these thicknesses are 1⁄5 of the thickness of the motor core C to be annealed.

An alternating current power supply 30 applying an alternating current to the outer induction coil 20 and the inner induction coil 21 forms, for example, a circuit in series, in other words, a current applied to the outer induction coil 20 and the inner induction coil 21 Connected to make the value the same. Each of the outer induction coil 20 and the inner induction coil 21 is configured to generate a magnetic flux along the axial direction (Z direction in FIG. 2) of the motor core C to be annealed by applying an alternating current.
The AC power supply 30 is, for example, configured to be variable in frequency, and in the present embodiment, is set to apply an AC current of, for example, a frequency of 10 kHz. The effect of changing the power supply frequency will be described later.

  As described above, since the magnetic flux is generated along the axial direction (Z direction in FIG. 2) of the motor core C to be annealed by the outer induction coil 20, the inner induction coil 21 and the AC power supply 30, the induction current is As a result, the motor core C to be annealed can be heated by the induction current. In particular, according to the present embodiment, the outer portion of the annealed motor core C is mainly heated by the induced current by the outer induction coil 20 provided on the outer side of the annealed motor core C, and the induced current by the inner induction coil 21 is mainly By heating the inner portion of the to-be-annealed motor core C, the entire outer surface of the inner peripheral portion and the outer peripheral portion of the to-be-annealed motor core C is induction-heated as described in detail with reference to FIGS. Heating can be performed according to the penetration depth (see the equation (1) described later, FIG. 16 and the like). Therefore, distortions generated during punching of the magnetic steel sheet constituting the motor core, and during fixation by caulking, screwing, welding, etc. are localized on the surface layer of the outer surface of the inner and outer peripheral portions of the motor core. Annealing to remove such localized strain can be performed in a short time.

  The outer induction coil 20 and the inner induction coil 21 are formed to be thinner in axial direction than the motor core C to be annealed, but as described later, the motor core C to be annealed can be moved in the axial direction Therefore, since it is possible to change the axial relative position between the outer induction coil 20 and the inner induction coil 21 and the motor core C to be annealed, the motor core C to be annealed can be heated over the entire axial direction.

  Subsequently, with respect to the inner mounting table 14, the intermediate mounting table 15, and the outer mounting table 16 as an example of the moving mechanism for changing the relative position between the outer induction coil and the inner induction coil and the to-be-annealed motor core in the axial direction, using FIG. Explain. 4 (A) shows the inside of the partition 11 before the axial movement of the motor core C to be annealed by the intermediate mounting table 15 and FIG. 4 (B) shows the inside of the partition 11 after moving.

  The inner mounting table 14, the intermediate mounting table 15, and the outer mounting table 16 in FIG. 4 constitute a moving mechanism for changing the relative position of the outer induction coil 20, the inner induction coil 21 and the annealed motor core C in the axial direction. The moving mechanism of the present invention is not limited to this.

  The inner mounting table 14 on which the inner induction coil 21 is mounted has a mounting plate 14 a on which the induction coil 21 is mounted, and a leg portion 14 b supporting the mounting plate 14 a.

  The outer mounting table 16 is for mounting the outer induction coil 20, and includes a mounting plate 16a on which the outer induction coil 20 is mounted, and a leg portion 16b for supporting the mounting plate 16a. The mounting surface of the outer induction coil 20 in the mounting plate 16a and the mounting surface of the inner induction coil 21 in the mounting plate 14a of the inner mounting table 14 have the same height in the axial direction.

  The intermediate mounting table 15 is for mounting the to-be-annealed motor core C, and has a mounting plate 15a on which the to-be-annealed motor core C is mounted, and a leg portion 15b for supporting the mounting plate 15a. While the axial length of the legs 14 b and 16 b of the inner mounting table 14 and the outer mounting table 16 is fixed, the leg 15 b of the intermediate mounting table 15 is equal to the axial length of the motor core C to be annealed. Accordingly, for example, it is configured to be extensible, and the length in the axial direction is variable.

  When heating the to-be-annealed motor core C, first, for example, as shown in FIG. 4A, the axial direction of the upper end portion of the to-be-annealed motor core C in the axial direction and the outer induction coil 20 and the inner induction coil 21 Power supply to the outer induction coil 20 and the inner induction coil 21 is started. Thereafter, the leg 15b is extended, and the mounting plate 15a on which the motor core C is mounted is placed such that the lower end of the motor core C in the axial direction approaches the outer induction coil 20 and the inner induction coil 21. , Move along the axial direction. That is, the relative position between the outer induction coil 20 and the inner induction coil 21 and the annealed motor core C in the axial direction is changed. Thereby, the entire motor core C to be annealed is heated. And as shown to FIG. 4 (B), the mounting board 15a is continued until the height of the said axial direction of the lower end part of the to-be-annealed motor core C and the lower end part of the outer induction coil 20 and the inner induction coil 21 corresponds. After the movement, the power supply from the AC power supply 30 is stopped, and the heating of the motor core C to be annealed is completed.

  As described above, the annealing apparatus 1 of this embodiment has a moving mechanism for changing the relative position between the outer induction coil 20 and the inner induction coil 21 and the to-be-annealed motor core C in the axial direction. be able to. In other words, as the outer induction coil 20 and the inner induction coil 21, one having a smaller thickness in the axial direction than the annealed motor core can be used. Therefore, the power supply capacity of AC power supply 30 which supplies power to outer induction coil 20 and inner induction coil 21 can be reduced. For example, in the case of a fixed type in which the axial thickness of the outer induction coil and the inner induction coil is equal to that of the motor core to be annealed and the relative positional relationship between these axial directions is not relatively changed Do. In this case, when the axial thickness of the outer induction coil 20 and the inner induction coil 21 is set to 1⁄5 of the annealed motor core C, and the positional relationship between the axial directions is relatively changed. The required power capacity is 20 kW.

  In the above-described example, the positions of the outer mounting plate 16a and the inner mounting plate 14a on which the outer induction coil 20 and the inner induction coil 21 are mounted are fixed, and the motor core C to be annealed is mounted. The axial position of the intermediate mounting plate 15a is variable, but the axial positions of the outer mounting plate 16a and the inner mounting plate 14a are variable, and the axial position of the intermediate mounting plate 15a is variable. May be fixed. Further, the position in the axial direction may be variable for all of the outer placement plate 16a, the inner placement plate 14a, and the intermediate placement plate 15a. When the positions of the outer mounting plate 16a and the inner mounting plate 14a in the axial direction are variable, the dimension of the lid 11a in the axial direction can be reduced. When the positions of the outer placement plate 16a and the inner placement plate 14a in the axial direction are made variable, it is preferable to synchronize the outer placement plate 16a and the inner placement plate 14a and move them in the axial direction. . It is because it can heat efficiently by this.

  Next, the method of performing induction heating for removing the distortion by punching etc. of the to-be-annealed motor core C with the annealing apparatus 1 is demonstrated using FIGS. 5-8. 5 to 8 are perspective views of 1/96 in the circumferential direction of the motor core C to be annealed and 1/5 in the axial direction (the lamination direction of the electromagnetic steel sheets) of the motor core C to be annealed. The back yoke portion Cb is shown on one side of the interposed tooth portion Ca. Further, the inner induction coil 21 is drawn on the side of the tooth portion Ca, and the outer induction coil 20 is drawn on the side of the back yoke portion Cb.

When the high frequency current Ia flows to the outer induction coil 20 at a certain moment, for example, in the positive direction of the Y direction, the high frequency current Ib flows to the inner induction coil 21 at the same moment in the negative direction of the Y direction. An alternating current power supply 30 is connected to the heating induction coil 10 so as to flow toward it.
The ampere-turn number (ampere turn) of the outer induction coil 20 is set to, for example, 1000 AT, and the ampere-turn number of the inner induction coil 21 is set to, for example, 3000 AT.

  Then, when an alternating current is applied to the heating induction coil 10 by the AC power supply 30, for example, as shown in FIG. 5, the outer induction coil 20 mainly lowers the back yoke portion Cb of the motor core C to be annealed at a certain moment A magnetic flux Φa is generated which passes in the direction (direction Z in the negative direction in FIG. 5). Further, the inner induction coil 21 generates a magnetic flux (b in the same direction as the magnetic flux Φa (the negative direction in the Z direction in FIG. 5) that passes mainly through the teeth Ca of the annealed motor core C at the same moment. Then, on the upper surface of the annealed motor core C where the density of both the magnetic flux aa and the magnetic flux bb is large, the magnetic flux aa and the magnetic flux bb strengthen each other, and the magnetic flux aa and the magnetic flux bb vertically enter the upper surface of the annealed motor core C. As a result, for example, as shown in FIG. 6, on the upper surface of the motor core C to be annealed, the magnetic flux Φa is reversely directed along the Y direction at the same moment so as to cancel the magnetic flux reinforced by the magnetic flux aa and the magnetic flux bb. The induced current In1a and the induced current In1b by the magnetic flux bb flow. Further, due to the magnetic flux bb generated by the inner induction coil 21, at the same moment on the surface of the teeth portion Ca (including the inner peripheral surface of the back yoke portion Cb), the induced current In2 circulates the teeth portion Ca to cancel the magnetic flux bb. Further, due to the magnetic flux aa generated by the outer induction coil 20, an induced current In3 flows around the outer peripheral surface of the back yoke portion Cb so as to cancel the magnetic flux aa.

  In the present embodiment, on the upper surface viewed from the through-hole direction of the to-be-annealed motor core C which does not require annealing, the induction currents In1a and In1b cancel each other, and heat generation due to induction heating is suppressed to a very slight extent. On the other hand, in the tooth portion Ca which needs to be particularly annealed, the surface layer region corresponding to the penetration depth (see the equation (1), FIG. 16 etc. described later) is unidirectionally without the induced current In2 canceling each other. Since it flows, annealing of strain localized in the surface layer is performed at a predetermined temperature by induction heating. Further, even on the outer peripheral surface of the back yoke portion Cb, which needs to be annealed as well, the induced current In3 flows in the surface layer region according to the penetration depth without canceling each other, so the annealing of the strain localized in the surface layer is induced by induction heating. It can be performed at a predetermined temperature.

  Further, in the present embodiment, magnetic flux Φa and 同 b in the same direction are generated in the area surrounded by the outer induction coil 20 and the inner induction coil 21, specifically, the area corresponding to the motor core C to be annealed. In applying an alternating current, the ampere turns of the outer induction coil 20 and the ampere turns of the inner induction coil 21 are set to different values. Therefore, even when outer induction coil 20 and inner induction coil 21 are connected to form a circuit in series with AC power supply 30, in other words, the current applied to outer induction coil 20 and inner induction coil 21 Even if the values are the same, the intensity (magnetic flux density) of the magnetic flux Φa, Φb generated from each outer induction coil 20 and inner induction coil 21 is changed, thereby adjusting the region where the induction currents In1a, In1b cancel each other it can. Therefore, by setting the ampere turns so that the induction currents In1a and In1b cancel each other in the region where heating is unnecessary, only the desired region can be efficiently heated, and the power consumption for the induction heating can be reduced. .

  For example, as shown in FIG. 7, when the AC power supply 30 is connected such that the current Ib flowing through the inner induction coil 21 at a certain moment is reverse to the direction shown in FIG. As a result, magnetic fluxes aa and bb are generated in opposite directions. If it does so, as shown in FIG. 8, since it is not necessary to cancel a magnetic flux like the case of above-mentioned FIG. Currents In1a and In1b flow. As a result, unnecessary induction heating occurs, for example, also in the back yoke portion Cb on the upper surface of the motor core C to be annealed, and power is wasted due to the induction heating. Therefore, in the case of heating the to-be-annealed motor core C using the induction coil 10 for heating according to the present embodiment, the magnetic flux 5a by the outer induction coil 20 and the inner induction coil 21 as shown in FIGS. It is preferable that the magnetic flux と な る b be in the same direction in the region corresponding to the motor core C to be annealed.

Further, in the above embodiment, since the frequency of the AC power supply 30 is variable, for example, by adjusting the frequency of the AC current to be applied, the penetration depth of the eddy current that causes induction heating is adjusted by the skin effect. it can. Therefore, for example, the frequency of AC power supply 30 can be adjusted in accordance with the distortion mode of annealed motor core C, and the optimum region can be induction heated. The frequency f of the AC power supply 30 is such that the penetration depth δ of the eddy current that causes induction heating corresponds to the introduction depth of the strain to be removed by annealing based on the following formula (1): It is determined.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: penetration depth of eddy current that causes induction heating: volume resistivity μ of the annealed motor core C: permeability f of the annealed motor core C: frequency of alternating current applied by the AC power supply 30

  Specifically, the frequency f of the AC power supply is determined, for example, such that the penetration depth δ of the eddy current that causes induction heating is substantially the same as the introduction depth of the strain to be removed by annealing. If the penetration depth δ of the eddy current and the introduction depth of the strain are substantially the same, the heat is introduced by the eddy current and the heat transfer from the portion heated by the eddy current is introduced into the motor core C to be annealed. Strain can be completely eliminated.

  In the above embodiment, the outer induction coil 20 and the inner induction coil 21 are connected to form a circuit in series with the AC power supply 30. However, for example, the outer induction coil 20 and the inner induction coil 21 are connected. Independent AC power supply may be connected. In such a case, the intensity distribution of each of the magnetic fluxes 誘導 a and Φb can be controlled by controlling the value of the current applied to the outer induction coil 20 and the inner induction coil 21. However, as shown in FIG. 7, in order to generate the magnetic flux Φa and Φb in opposite directions, it is necessary to synchronize the frequency and the phase of the alternating current applied to the outer induction coil 20 and the inner induction coil 21. As in the embodiment, the outer induction coil 20 and the inner induction coil 21 are connected to the AC power supply 30 so as to form a circuit in series, and the control of the intensity distribution of each magnetic flux Φa, bb is the outer induction coil It is preferable to carry out by setting of the number of ampere turns of the inner induction coil 21 and 20.

Second Embodiment
FIG. 9 is a longitudinal sectional view showing the outline of the configuration of the annealing apparatus according to the second embodiment of the present invention. FIG. 10 is an explanatory view of a rotation drive unit described later provided in the annealing apparatus of FIG. 9.
In addition to the component similar to the annealing apparatus of 1st Embodiment, the rotational drive part 40 is provided with the annealing apparatus 1 of FIG.

  The rotation drive unit 40 is configured to rotate the intermediate mounting table 15, and is formed of, for example, a motor or the like, and is provided at the root of the leg 15 b that supports the mounting plate 15 a of the intermediate mounting table 15. The rotational shaft of the intermediate mounting table 15 is aligned with the central axis of the motor core C to be annealed, and the intermediate mounting table 15 is rotated by the rotation driving unit 40 to rotate the motor core C to be annealed about its central axis. Can. That is, the rotation drive part 40 also rotates the to-be-annealed motor core C. In addition, the rotational axis of the intermediate mounting table 15 is made to coincide with the central axes of the outer induction coil 20 and the inner induction coil 21 as well as the central axis of the motor core C to be annealed. By doing this, as shown in FIG. 10, the annealed motor core C can be rotated relative to the outer induction coil 20 and the inner induction coil 21. That is, the rotational drive unit 40 can relatively rotate the outer induction coil 20 and the inner induction coil 21 and the motor core C to be annealed.

By the way, in the first embodiment having no rotational drive portion, the magnetic flux generated by the outer induction coil 20 is not good in the circumferential direction of the outer induction coil 20, that is, in the circumferential direction of the motor core C to be annealed. It may be uniform. In that case, the induction current generated in the to-be-annealed motor core C by the magnetic flux becomes uneven in the circumferential direction of the to-be-annealed motor core C, and as a result, the temperature difference in the circumferential direction to the to-be-annealed motor core C heated by the induced current Occurs. The same applies to the inner induction coil 21.
As in the present embodiment, by providing the rotary drive unit 40 and relatively rotating the outer induction coil 20 and the inner induction coil 21 and the motor core C to be annealed, the above-mentioned circumferential temperature difference is prevented from being generated. Can.

  The rotational speed by the rotational drive unit 40 is such that it rotates at least once during the heating time by the outer induction coil 20 and the inner induction coil 21, and preferably it rotates 10 times during the heating time. It is.

Third Embodiment
FIG. 11 is a longitudinal sectional view showing the outline of the configuration of the annealing apparatus according to the third embodiment of the present invention.
The annealing device 1 of FIG. 11 is provided with a cooling device 50 in the partition wall 11 in addition to the same components as the annealing device of the first embodiment.

The cooling device 50 cools the to-be-annealed motor core C heated by the induction coil 10 for heating. In this example, the cooling device 50 is provided so as to be continuous with the heating induction coil 10 along the axial direction of the annealed motor core C, and is positioned vertically below the heating induction coil 10.
Cooling device 50 has an outer cooling device 51 that cools the motor core C to be annealed from the outside, and an inner cooling device 52 that cools the motor core C to be annealed from the inside.
As a cooling medium of the cooling device 50, a reducing gas such as an inert gas such as nitrogen gas or a hydrogen gas is used to prevent rusting of the annealed motor core C.

  Further, in the annealing apparatus 1 of the present embodiment, in order to make the inside of the partition 11 a low oxygen atmosphere, an atmosphere gas such as nitrogen gas is supplied into the inside of the partition 11 via the gas supply pipe 13. Although not shown, an exhaust pipe is connected to the lid portion 11 a of the partition 11 so that the pressure in the partition 11 falls within a predetermined range.

  Then, the annealing process of the to-be-annealed motor core C using the annealing apparatus 1 of this embodiment is demonstrated using FIG.12 and FIG.13. FIG. 12 shows the inside of the partition 11 before the axial movement of the motor core C to be annealed by the intermediate mounting table 15, and FIG. 13 shows the inside of the partition 11 after moving.

  When annealing the to-be-annealed motor core C, for example, as shown in FIG. 12, the induction for heating from the AC power supply 30 is performed with the lower end portion of the to-be-annealed motor core C in the axial direction facing the induction coil 10 for heating. Power supply to the coil 10 is started, and heating of the motor core C to be annealed is started. At that time, ejection of the cooling medium from the cooling device 50, specifically, ejection of the cooling medium directed inward from the outer cooling device 51, and ejection of the cooling medium directed outward from the inner cooling device 52 are also started. . Thereafter, the mounting plate 15a on which the motor core C is mounted is set in the axial direction so that the leg portion 15b is shrunk and the upper end portion in the axial direction of the motor core C to be annealed approaches the induction coil 10 for heating. Move along Thereby, the entire to-be-annealed motor core C is heated, and the portion of the to-be-annealed motor core C heated by the induction coil for heating 10 is cooled by the cooling device 50. Then, as shown in FIG. 13, when the mounting plate 15 a is moved to a position where the upper end portion of the to-be-annealed motor core C faces the cooling device 50, the power supply from the AC power supply 30 and the cooling device 50 The ejection of the cooling medium is stopped, and the annealing of the target motor core C is completed.

In the annealing of the motor core, it is necessary to cool the motor core to a predetermined temperature after heating. In the present embodiment, as described above, since the cooling device 50 is provided in addition to the induction coil 10 for heating, the time required for the annealing of the motor core C to be annealed including the cooling to the predetermined temperature is significantly shortened. can do.
Further, in the present embodiment, the cooling device 50 is provided so as to be connected to the induction coil 10 for heating along the axial direction of the motor core C to be annealed, that is, the moving direction of the motor core C to be annealed Can be performed following the heating by the heating induction coil 10. Therefore, the distance between the heating induction coil 10 and the cooling device 50 and the moving distance of the annealed motor core C between the heating induction coil 10 and the cooling device 50 can be reduced, so the size of the annealing device 1 Annealing can be completed in a short time without upsizing.

Cooling device 50 is provided at a predetermined position based on heating induction coil 10, for example, a position separated by one motor core from heating induction coil 10. Specifically, for example, the distance L (see FIG. 11) from the lower end of the heating area by the induction coil 10 for heating to the upper end of the cooling area by the cooling device 50 is equal to or longer than the axial length of one annealed motor core C The cooling device 50 is provided at such a position as
By providing the cooling device 50 at such a position, it is possible to prevent the heating by the heating induction coil 10 from being inhibited by the cooling by the cooling device 50.

  In the above example, the cooling device 50 includes both the outer cooling device 51 and the inner cooling device 52, but may have one of the devices 51 and 52.

In the above example, the ejection start timing of the cooling medium was at the start of heating of the motor core C to be annealed, but when the motor core C to be annealed reaches the cooling region by the cooling device 50, ejection of the cooling medium is started You may
Further, in the above example, the stop timing of the power supply from the AC power supply 30 is the time when the cooling by the cooling device 50 is stopped, but when the motor core C to be annealed is out of the heating region by the induction coil 10 for heating The power supply may be stopped.

Fourth Embodiment
FIG. 14 is a longitudinal sectional view showing the outline of the configuration of the annealing apparatus according to the fourth embodiment of the present invention.
In the annealing apparatus of the above 1st-3rd embodiment, it had both the outer side induction coil 20 and the inner side induction coil 21. FIG.
On the other hand, as shown in FIG. 14, the annealing apparatus 1 according to the present embodiment has only the inner induction coil 21 as the induction coil 10 for heating, and the inner induction coil 21 causes the inner peripheral portion of the motor core C to be annealed. Only the surface layer is heated, and only the strain in the inner circumferential portion is annealed. The frequency of the AC power supply 30 supplied to the inner induction coil 21 is selected to satisfy the above-mentioned equation (1) in relation to the depth of strain to be removed by annealing. Further, the alternating current applied by the alternating current power supply 30 to the inner induction coil 21 suppresses the temperature inside the annealed motor core C to 500 ° C. or less, while the strained portion (hereinafter referred to as a strain introducing portion), that is, the machined surface Those capable of heating to 750 ° C. to 850 are selected.

  When the to-be-annealed motor core C is a stator core having a slot formed in the inner circumferential portion thereof, it may be necessary to anneal only the inner circumferential portion. In such a case, by providing only the inner induction coil 21 as in the present embodiment and annealing by induction heating by the inner induction coil 21, the inner induction coil 21 and the outer induction coil as in the first to third embodiments. The equipment cost can be reduced as compared to the case where both of the twenty are provided. Further, in the case where it is sufficient to anneal only the inner peripheral portion of the motor core to be annealed as described above, annealing is performed by the annealing device 1 having only the inner induction coil 21 as in this embodiment. As described above, the induction coil provided on the outer side of the motor core to be annealed can perform annealing with less electric power and in a short time as compared to the case where the strain of the inner peripheral portion of the motor core to be annealed is annealed. This is because, in the induction heating devices of Patent Documents 1 to 3, the induction coil is provided on the outer side of the motor core to be annealed, so that not only the strain introducing portion of the inner peripheral portion but also other portions than the strain introducing portion such as the back yoke portion are heated On the other hand, in the present embodiment, by installing the induction coil inside the coil to be annealed and making the penetration depth of the induction current extremely small, it is possible to target and heat only the strain introduction part.

FIG. 15 shows that when the motor core C to be annealed is heated by the annealing apparatus 1 according to this embodiment, specifically, the alternating current from the AC power supply 30 does not change the positional relationship between the inner induction coil 21 and the motor core C to be annealed. Is supplied to the inner induction coil 21 for 3 minutes to heat the to-be-annealed motor core C, and then the temperature history when the to-be-annealed motor core C is naturally cooled without cooling by the cooling device 50 is shown. The horizontal axis in FIG. 15 represents time, and the vertical axis represents temperature.
According to the annealing device 1 according to the present embodiment, the temperature of the inner peripheral portion which is the strain introduction portion of the motor core C to be annealed can be raised to 750 to 850 ° C. in a very short time of 3 minutes. In addition, since the inside of the core of the annealed motor core C is maintained at 500 ° C. or less when raising the temperature, that is, the amount of heat given to the entire annealed motor core C at the time of annealing is suppressed. It is possible to cool down to 200 ° C. in a very short time of about 8 minutes without cooling by means of If the cooling device 50 is used, it can cool in a short time.

In the present embodiment, although the induction coil 10 for heating of the annealing apparatus 1 has only the inner induction coil 21, when the motor core C to be annealed is a rotor core having a slot formed on the outer peripheral portion thereof, The heating induction coil 10 may have only the outer induction coil 20. That is, the annealing apparatus 1 of this embodiment has an induction coil in the side in which the slot is formed among the inner side of the to-be-annealed motor core C, and the outer side.
Also in this embodiment, a small-sized induction coil can be used as either one of the outer induction coil 20 and the inner induction coil 21. Therefore, the power supply capacity of the AC power supply for supplying power to either one of the above can be used. It can be made smaller.

  Moreover, in the present embodiment, when the cooling device 50 has only the inner cooling device 52, and as described above, when the heating induction coil 10 has only the outer induction coil 20, the cooling device 50 also has the outer cooling device. It may have only 51. Thus, the cooling device 50 may have the same side as the side having the heating induction coil 10 among the outer cooling device 51 and the inner cooling device 52.

As an example of the present invention, a simulation was performed on the heat generation density in the case of induction-heating the motor core C to be annealed using the annealing apparatus 1 according to the first embodiment of the present invention. The outer diameter of the to-be-annealed motor core C was 210 mm, the inner diameter was 134 mm, one motor core was used as the to-be-annealed motor core C, and the axial thickness was 52 mm. In addition, the thickness of the electromagnetic steel plate which comprises the to-be-annealed motor core C is 0.35 mm. Further, the volume resistivity of the motor core C to be annealed was 5.2 e- ⁷ ? M in the plane, and the axial direction was infinite. As the induction coil 10 for heating, the outer induction coil 20 had an inner diameter of 220 mm, a thickness of 10 mm in the diameter direction, and a thickness of 10 mm in the axial direction. The inner induction coil 21 had an inner diameter of 114 mm, a thickness of 10 mm in the diameter direction, and a thickness of 10 mm in the axial direction. Further, the axial center position of the outer induction coil 20 and the inner induction coil 21 and the axial center position of the annealed motor core C coincide with each other. Then, the frequency of the alternating current power source 30 for applying alternating current to the outer induction coil 20 and the inner induction coil 21 is changed to 1 kHz, 10 kHz and 50 kHz, and the axial center position of the motor core C to be annealed is shown in FIG. I got the data. The horizontal axis in FIG. 16 is the depth from the surface, and the vertical axis is the heat generation density.

  As shown in FIG. 16, it can be confirmed that the heat generation density in the region deep from the surface is lowered by the skin effect as the frequency of the AC power supply 30 is increased. Therefore, it is understood from this result that the depth to be heated by induction heating can be set by appropriately adjusting the frequency of the AC power supply 30. In addition, since the depth of distortion generated by punching of the magnetic steel sheet is generally about half of the thickness of the magnetic steel sheet, for example, when the thickness of the magnetic steel sheet is about 0.35 mm, the frequency of the AC power supply 30 is It may be set to approximately 10 kHz or more.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modifications or alterations within the scope of the idea described in the claims, and they are naturally within the technical scope of the present invention. It is understood that.

  The present invention is generated when forming a motor core by securing the distortion caused by punching of the magnetic steel sheet constituting the motor core or by sticking the plural punched electromagnetic steel sheets in a laminated state by caulking, screwing, etc. It is useful in annealing the motor core in order to remove such distortion.

DESCRIPTION OF SYMBOLS 1 annealing apparatus 10 induction coil 11 for heating 11 partition wall 11a lid part 11b bottomed container part 12 heat insulation material 13 gas supply pipe 14 inner mounting table 14a (inside) mounting plate 14b leg part 15 intermediate mounting table Motor core mounting table)
15a (intermediate) mounting plate 15b leg 16 outer mounting table 16a (outside) mounting plate 16b leg 20 outer induction coil 21 inner induction coil 30 AC power supply C motor core (annealed motor core)
Ca teeth Cb Back yoke Cc Slot 40 Rotational drive 50 Cooling device

Claims (12)

An apparatus for laminating and annealing one or a plurality of motor cores formed by laminating electromagnetic steel sheets after punching.
The one or a plurality of laminated motor cores (hereinafter simply referred to as "a plurality of annealed motor cores") are arranged on the outer side of the annealed motor cores concentrically, and the electromagnetic steel sheets are stacked from the annealed motor cores An annular outer induction coil having a small thickness in a direction (corresponding to the axial direction of the motor core, hereinafter referred to as the axial direction), and concentrically with the to-be-annealed motor core inside the to-be-annealed motor core One or both of the annular inner induction coils whose axial thickness is smaller than that of the motor core to be annealed;
An alternating current source for applying an alternating current to the outer induction coil and / or the inner induction coil;
A motor core annealing apparatus comprising: a moving mechanism for changing a relative position between the outer induction coil and / or the inner induction coil and the to-be-annealed motor core in the axial direction. The motor core annealing apparatus according to claim 1, wherein the moving mechanism moves the to-be-annealed motor core in the axial direction. The motor core annealing apparatus according to claim 1 or 2, wherein the moving mechanism moves the induction coil at least on the side facing the slot-formed side of the annealed motor core in the axial direction. Comprising both the outer induction coil and the inner induction coil,
The motor core annealing device according to any one of claims 1 to 3, wherein the moving mechanism moves the outer induction coil and the inner induction coil in synchronization in the axial direction. Comprising both the outer induction coil and the inner induction coil,
The alternating current power supply applies an alternating current to the outer induction coil and the inner induction coil so as to generate an alternating magnetic flux in the same direction in a region surrounded by the outer induction coil and the inner induction coil. The motor core annealing apparatus according to any one of claims 1 to 4, characterized in that Comprising both the outer induction coil and the inner induction coil,
The motor core annealing device according to claim 5, wherein the outer induction coil and the inner induction coil are connected to form a circuit in series with the alternating current power supply. The motor core annealing apparatus according to any one of claims 1 to 6, wherein a frequency of an alternating current applied by the alternating current power supply is 10 kHz or more. A partition for adjusting an annealing atmosphere, which accommodates the to-be-annealed motor core inside;
The motor core annealing device according to any one of claims 1 to 7, further comprising: a heat insulating material that covers the outer side or the inner side of the partition wall. The motor core annealing apparatus according to any one of claims 1 to 8, further comprising a cooling device for cooling a heating portion of the annealed motor core heated by the outer induction coil and / or the inner induction coil. . The motor core according to any one of claims 1 to 9, further comprising a rotational drive mechanism that relatively rotates the to-be-annealed motor core and the outer induction coil and / or the inner induction coil. Annealing equipment. A motor core annealing method for removing distortion introduced in the outer peripheral surface and / or the inner peripheral surface of the motor core to be annealed using the motor core annealing device according to any one of claims 1 to 10,
The induction heating of the to-be-annealed motor core is performed by an alternating current of a frequency f of an alternating current power supply determined to be a penetration depth δ in the following formula (1) according to the introduction depth of the strain,
A method for annealing a motor core, comprising raising the temperature of the outer peripheral surface and / or the inner peripheral surface of the motor core to be annealed to 750 to 850 ° C.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: penetration depth of eddy current causing induction heating: volume resistivity μ of the motor core to be annealed: permeability of the motor core to be annealed f: frequency of alternating current applied by the AC power supply The motor core according to claim 11, wherein the temperature of the outer peripheral surface and / or the inner peripheral surface is raised to 750 to 850 ° C while suppressing the temperature inside the annealed motor core to 500 ° C or less. Method.

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