JP2019170086A - Annealing device of motor core and annealing method of motor core - Google Patents

Abstract

To perform annealing for removing deformation generated in die cutting of electrical steel constituting a motor core, and in fastening due to calking, screw fastening and weld, etc. in short time.SOLUTION: An annealing device for annealing a motor core C has: an annular outside induction coil 40 and/or an inside induction coil 10 concentrically arranged with the motor core C outside and/or inside the motor core C to be annealed; an AC power supply which applies AC current to the induction coils; a cooling apparatus 11 which sprays a cooling medium to a heating part of the motor core C heated by the induction coils to cool the motor core C; and a movement mechanism which varies a relative position between the outside induction coil 40 or the inside induction coil 10 and the motor core C, and a relative position between the cooling apparatus 11 and the motor core C.SELECTED DRAWING: Figure 4

Description

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

The motor core is fixed to a motor case that is fixed around the motor rotation shaft (output shaft, output shaft) and rotates, and is fixed to the motor case coaxially with the rotor core. There is a stator (stator) core that generates a rotational force in the rotor by the interaction of electromagnetic force between the outer periphery of the rotor and the inner periphery of the rotor.
A motor core (iron core) manufactured by laminating a number of materials punched from a non-oriented electrical steel sheet into a predetermined shape and fixed by caulking, screwing, welding, etc., is used when stamping the steel sheet, caulking or screwing. Since iron loss deteriorates due to strain generated when fixing by fixing, welding, or the like, it is usually heated for a predetermined time by a continuous or batch annealing furnace in order to remove this strain. In an annealing furnace, for example, it is heated by radiant heat from an electric heater or the like and conduction heat by an atmospheric gas (see the background art of Patent Document 1).

  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 5 is known. In the methods disclosed in Patent Documents 1 to 4, not only the entire annealing of the motor core but also the “partial annealing around the slot (iron slot) of the stator core” of Patent Document 1, for example. The induction coil is heated outside the motor core. Further, in the method disclosed in Patent Document 5, when a slot is provided in the inner peripheral portion of the motor core, both the induction coil provided outside the motor core and the induction coil provided inside the motor core are used. The inner peripheral portion and the outer peripheral portion of the annealed motor core are heated.

  Furthermore, in Patent Document 4, after heating the motor core to 800 ° C. or higher in a heating furnace equipped with an induction heating coil, atmospheric gas is fed into the heating furnace from one end of the heating furnace and discharged from the other end. And cooling the motor core.

JP-A-62-272843 JP 2003-342637 A JP 58-104125 A JP 58-222761 A JP 2017-110243 A

  By the way, in recent years, in the production of drive motors and motor cores of generators such as hybrid vehicles (HEV) and electric vehicles (EV), which require high productivity, it is required to shorten the annealing time in order to improve productivity. ing. However, in radiant heating using an electric heater or the like, there is a limit to shortening the heating time. In addition, in short-time annealing by radiant heating, there is a problem that the temperature distribution is not uniform in the height direction of the motor core and in the back and front of the teeth portion where the strain at the time of punching is particularly large.

Further, the induction heating apparatus disclosed in Patent Documents 1 to 4 has an induction coil arranged outside the motor core even when the distortion to be annealed is annealing of the stator core formed mainly on the inner peripheral side. Due to the installation, etc., it takes time to heat, so there is a limit to shortening the annealing time.
Furthermore, the motor core annealing device by induction heating disclosed in Patent Document 5 needs to perform cooling of the motor core after induction heating, for example, outside the motor core annealing device. There is room for improvement.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and annealing of a motor core that removes, in a short time, distortion generated during punching of an electromagnetic steel sheet constituting the motor core, or by fixing by caulking, screwing, welding, or the like. An object is to provide an apparatus and an annealing method.

  In order to achieve the above object, the present invention provides an apparatus for laminating one or more motor cores formed by laminating electromagnetic steel sheets after punching, and annealing the one or more motor cores. (Hereinafter simply referred to as “annealed motor core”, including a plurality of cases), an annular outer induction coil arranged concentrically with the annealed motor core, and the annealed inside of the annealed motor core. An AC power supply for applying an AC current to the outer induction coil and / or the inner induction coil, and any one or both of an annular inner induction coil arranged concentrically with the motor core; A cooling medium is sprayed on the heating part of the to-be-annealed motor core heated by the induction coil and / or the inner induction coil to cool the to-be-annealed motor core. And a moving mechanism that changes a relative position between the outer induction coil and / or the inner induction coil and the annealed motor core and a relative position between the cooling device and the annealed motor core. Yes.

  According to the present invention, punched electromagnetic steel sheets for motor cores are heated by induction heating, depending on the use, of laminated steel sheets that are laminated and fixed by caulking, screwing, welding, or the like into a motor core shape. In this case, annealing can be performed in a short time in order to remove strain generated during fixing by caulking, screwing, welding, or the like. Moreover, since a cooling device is provided, the time required for annealing including cooling time can be shortened. The motor core targeted by the present invention includes both a stator core (stator) and a rotor core (rotor).

  The cooling device may be arranged side by side along the axial direction of the outer induction coil and / or the inner induction coil and the annealed motor core.

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

  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 outer side or the inner side of the said partition.

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

Another aspect of the present invention is a method for annealing a motor core, wherein any of the motor core annealing apparatuses described above is used to remove strain introduced into the outer peripheral surface and / or inner peripheral surface of the annealed motor core. Then, the strain introduction depth is associated with the penetration depth δ in the following formula (1), the motor core is induction-heated by an alternating current of the frequency f of the AC power source obtained from the following formula (1), and the motor core A method for annealing a motor core, wherein the temperature of the slot forming surface of the motor core is raised to 750 to 850 ° C. while suppressing the internal temperature to 500 ° C. or lower.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: penetration depth of eddy current causing induction heating ρ: volume resistivity of the motor core
μ: Magnetic permeability of the motor core f: Frequency of AC current applied by the AC power source

  ADVANTAGE OF THE INVENTION According to this invention, the annealing of a motor core for removing the distortion which arose at the time of the punching of the electromagnetic steel plate which comprises a motor core, and the adhering by crimping, screwing, welding, etc. can be performed in a short time. .

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 with respect to an inner side 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 which shows an example of the annealing method using the annealing apparatus concerning 1st 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 1st Embodiment of this invention. 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 rotational 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 longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 4th Embodiment of this invention. It is a graph which shows the relationship between the frequency of an alternating current, a heat generation density, and the depth from the surface. It is a figure which shows the difference of the temperature rising aspect by the site | part of a to-be-annealed motor core.

(First embodiment)
The first embodiment of the present invention will be described below. FIG. 1 is a longitudinal sectional view showing an outline of a configuration of an annealing apparatus according to the present embodiment. FIG. 2 shows a motor core to be annealed with respect to the inner induction coil of the annealing apparatus (a case where the motor core is a group of motor cores in which one or a plurality of motor cores to be annealed are arranged in the axial direction, and an area occupied by the motor core to be annealed. For convenience of explanation, there is a case where the region is treated as if the annealed motor core is present in the region.) FIG. FIG. 3 is a diagram 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. In the following description, the explanation will be made mainly on the annealing of the stator core. Since it is applicable also to annealing, it is not necessary to distinguish both, and the term of the motor core which generically refers to both is used. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  The annealing apparatus 1 of FIG. 1 performs annealing of an annealed motor core C manufactured by laminating a plurality of materials punched out of a non-oriented electrical steel sheet into a predetermined shape and fixing them by caulking, screwing, welding, etc. Of the strains generated during punching and when fixed by caulking, screwing, welding, etc. (hereinafter, sometimes referred to as “strain due to punching”), they occurred mainly on the inner peripheral surface of the motor core C to be annealed. This is to remove strain. The annealing device 1 includes an inner induction coil 10 as an annealing induction coil, a cooling device 11, a partition wall 12, and a heat insulating material 13.

  The partition wall 12 is for adjusting the annealing atmosphere in which the motor core C to be annealed is housed, and has, for example, a substantially cylindrical lid portion 12a having an open bottom surface and a bottomed container portion 12b having an open top surface. For example, the inside of the partition wall 12 can be kept airtight by water sealing. A gas supply pipe 12 c that supplies an atmospheric gas such as nitrogen is connected to the lid 12 a inside the partition wall 12.

  As an example of a moving mechanism that changes a relative position between the inner induction coil 10 and the motor core C to be annealed and a moving mechanism that changes the relative position between the cooling device 11 and the motor core C to be annealed, A mounting table 14 and a core mounting table 15 are provided. The details of these mounting tables 14 and 15 will be described later. Among these mounting tables 14 and 15, the core mounting table 15 on which the motor core C to be annealed is mounted is the axial direction of the motor core C to be annealed (the Z direction in FIG. 1). The axial direction of the inner induction coil 10 and the cooling device 11 also coincides.) The motor core C to be annealed is configured to be movable along the inner induction coil 10 and the cooling device 11.

  The heat insulating material 13 covers the outside of the partition wall 12. If this heat insulating material 13 is arrange | positioned, the thermal efficiency of the annealing apparatus 1 of the to-be-annealed motor core C can be improved, and it is preferable. In addition, the material, form, etc. of the heat insulating material 13 are not specifically limited, For example, materials, such as well-known inorganic materials, such as calcium silicate and an alumina, are various, such as cotton shape, cloth shape, plate shape, foam shape, etc. What was processed into various forms can be used. Moreover, although the example arrange | positioned so that the outer side of the partition 12 may be enclosed as an installation position of the heat insulating material 13 is shown in FIG. 1, it does not interfere with the to-be-annealed motor core C, the partition 12, etc. If it is a position, you may arrange | position so that the inner side of the partition 12 may be covered.

  For example, as shown in FIG. 2, the inner induction coil 10 is an annular member that is disposed inward of the motor core C to be annealed and concentrically with the motor core C to be annealed. By the way, the to-be-annealed motor core C here is a stator core and is formed in a cylindrical shape, and as shown in FIG. 3, slots Cc (slot;) formed at equal intervals on the inner periphery of the to-be-annealed motor core C. Iron core groove). Therefore, it can be explained that the inner induction coil 10 is provided on the inner peripheral side facing the side where the slot Cc is formed, of the outer peripheral side and the inner peripheral side of the annealed motor core C.

The to-be-annealed motor core C has a back yoke (back) that connects a teeth portion Ca, which is a partition provided between the slots Cc, and an outer peripheral end of the teeth portion Ca.
yoke; rear yoke, successor iron) portion Cb. The slot Cc is formed over the entire length of the motor core C in the axial direction (the Z direction in FIG. 2, which coincides with the lamination direction of the electromagnetic steel sheets).

Returning to the explanation of the inner induction coil 10.
As shown in FIGS. 1 and 2, the inner induction coil 10 is formed to be thicker in the axial direction than the annealed motor core C.
The inner induction coil 10 is connected to an AC power source 20 that applies an AC current. Furthermore, the inner induction coil 10 is configured to generate a magnetic flux along the axial direction (Z direction in FIG. 2) of the to-be-annealed motor core C by applying an alternating current.
The AC power supply 20 is configured to be variable in frequency, for example, and in this embodiment, is set to apply an AC current having a frequency of 10 kHz, for example. The effect of changing the power supply frequency will be described later.

  As described above, magnetic flux is generated along the axial direction (Z direction in FIG. 2) of the to-be-annealed motor core C by the inner induction coil 10 and the AC power source 20, and therefore an induced current is generated in the to-be-annealed motor core C. Thus, the to-be-annealed motor core C can be heated. In particular, according to the present embodiment, in order to cancel the magnetic flux described above, the entire outer surface of the inner peripheral portion of the annealed motor core C, that is, the surface of the teeth portion Ca of the stator core (inside the back yoke portion Cb) Since the induced current flows over the entire area (including the peripheral surface), the surface layer area corresponding to the penetration depth of the induced current (see formula (1), FIG. 10, etc. described later) in the inner peripheral portion of the annealed motor core Can be induction heating. Therefore, the strain localized in the surface layer of the inner peripheral portion of the annealed motor core C, which causes the iron loss of the motor core, more specifically, the surface layer of the teeth portion Ca and the back yoke portion Cb of the stator core. Strain localized in the surface layer of the inner peripheral surface can be annealed at a predetermined temperature.

The cooling device 11 sprays a cooling medium on the inner peripheral surface of the annealed motor core C heated by the inner induction coil 10, that is, the slot forming surface, and cools the annealed motor core C, and is provided in the partition wall 12. ing. In this example, the cooling device 11 is arranged with the inner induction coil 10 along the axial direction of the to-be-annealed motor core C, and specifically, is positioned below the inner induction coil 10 in the vertical direction.
In addition, in order to prevent rust generation | occurrence | production to the to-be-annealed motor core C, reducing gas, such as inert gas, such as nitrogen gas, and hydrogen gas is used for the cooling medium of the cooling device 11. FIG.

  Moreover, in the annealing apparatus 1 of this embodiment, in order to make the inside of the partition 12 into a low oxygen atmosphere, atmospheric gas, such as nitrogen gas, is supplied into the partition 12 through the gas supply pipe 12c as described above. Yes. And although illustration is abbreviate | omitted, the exhaust pipe is connected to the cover part 12a of the partition 12 so that the pressure in the partition 12 may be settled in a predetermined range.

  Next, the coil mounting table 14 and the core mounting table 15 that are examples of a moving mechanism that changes the relative position between the inner induction coil 10 and the motor core C to be annealed and the relative position between the cooling device 11 and the motor core C to be annealed will be described. .

The coil mounting table 14 includes a mounting plate 14a on which the inner induction coil 10 is mounted, and leg portions 14b that support the mounting plate 14a. The cooling device 11 is fixed to the leg portion 14b below the mounting plate 14a.
The core mounting table 15 includes a mounting plate 15a on which the to-be-annealed motor core C is mounted, and leg portions 15b that support the mounting plate 15a. In addition, while the axial direction length of the to-be-annealed motor core C of the leg part 14b of the coil mounting base 14 is fixed, the leg part 15b of the core mounting base 15 is configured to be stretchable, for example, and the to-be-annealed motor core The length of C in the axial direction is variable.

Next, an annealing method using the annealing apparatus 1 will be described with reference to FIG. FIG. 4A shows the inside of the partition wall 12 being heated, and FIG. 4B shows the inside of the partition wall 12 being cooled.
When annealing the motor core C to be annealed, first, as shown in FIG. 4A, for example, the motor core C to be annealed faces the central portion of the inner induction coil 10 in the axial direction of the motor core C to be annealed. The mounting plate 15a of the core mounting table 15 is moved. And in the state which opposed as mentioned above, the electric power supply from the alternating current power supply 20 to the inner side induction coil 10 is started, and the heating of the to-be-annealed motor core C is started.

  The magnitude and application time of the AC current applied to the inner induction coil 10 by the AC power source 20 during heating are the portion where the strain to be annealed in the annealed motor core C (hereinafter referred to as strain introduction portion), that is, the inner peripheral portion. The maximum reached temperature of the surface layer of 750 to 850 ° C., more specifically, the maximum reached temperature of the surface layer of the inner peripheral portion is 750 to 850 ° C., and the maximum reached temperature inside the annealed motor core C is 500 ° C. or less. Is selected.

As described above, since the frequency of the AC power supply 20 is variable, by adjusting the frequency, an eddy current that causes induction heating of the annealed motor core C, that is, a penetration depth of the induced current, can be obtained by the skin effect. Can be adjusted. Therefore, for example, the frequency of the AC power supply 20 can be adjusted according to the distortion mode of the annealed motor core C, and the optimum region can be induction-heated. Therefore, in the annealing method according to the present embodiment, the frequency f of the AC power supply 20 correlates the introduction depth of strain to be removed by annealing with the eddy current penetration depth δ of the following formula (1). The frequency obtained from the following formula (1) that gives the depth is selected.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: Penetration depth of eddy current causing induction heating ρ: Volume resistivity of annealed motor core C μ: Magnetic permeability of annealed motor core C f: Frequency of AC current applied by AC power supply 20

  After the heating as described above is finished, the power supply from the AC power supply 20 is stopped.

  Thereafter, ejection of the cooling medium from the cooling device 11, specifically, ejection of the cooling medium from the cooling device 11 toward the outside is started. At the same time, as shown in FIG. 4B, the leg portion 15b of the core mounting table 15 is contracted so that the annealed motor core C faces the central portion in the axial direction of the annealed motor core C in the cooling device 11. The mounting plate 15a on which the motor core C to be annealed is mounted is moved along the axial direction. Thereby, the heating part of the to-be-annealed motor core C heated by the inner induction coil 10 is cooled by the cooling device 11. And when the to-be-annealed motor core C is cooled to predetermined temperature, the ejection of the cooling medium from the cooling device 11 is stopped, and annealing of the to-be-annealed motor core C is completed.

  In the present embodiment, when only the slot forming portion, that is, the inner peripheral portion of the motor core C to be annealed needs to be annealed, the inner induction coil 10 disposed inside the motor core C to be annealed is annealed as described above. Therefore, as in Patent Documents 1 to 3, annealing is performed with a small amount of electric power and in a short time compared to the case where the distortion of the inner peripheral portion of the annealed motor core is annealed by the induction coil provided outside the annealed motor core. be able to. This is because in the induction heating devices of Patent Documents 1 to 3, since the induction coil is provided outside the to-be-annealed motor core, it is necessary to increase the penetration depth of the induction current in order to heat the strain introduction portion in the inner peripheral portion. As a result, other than the strain-introducing part such as the back yoke part is heated, but in this embodiment, the inner induction coil 10 is installed inside the annealed motor core, and the penetration depth of the induced current is increased. This is because by making it very small, it is possible to heat only the strain introduction part of the slot forming part.

  In addition, in the present embodiment, as described above, since the cooling device 11 is provided in addition to the inner induction coil 10 as the heating induction coil, up to a predetermined temperature of the heated portion of the motor core C to be annealed. The time required for annealing the to-be-annealed motor core C including the cooling of can be greatly shortened. Furthermore, in this embodiment, since the cooling medium is sprayed from the cooling device 11 to the slot forming surface of the to-be-annealed motor core C as described above, the cooling is performed by the atmospheric gas fed into the heating furnace as in Patent Document 4. Compared to the case, the slot forming surface can be rapidly cooled.

  Moreover, in this embodiment, the highest ultimate temperature of the surface layer of the inner peripheral part which is a distortion | strain introduction part in the to-be-annealed motor core C is 750-850 degreeC, and the highest attainable temperature inside the to-be-annealed motor core C is 500 degrees C or less. Induction heating is performed. That is, in this embodiment, the strain introduction part in the to-be-annealed motor core C is locally induction-heated. Therefore, the strain introduction part can be annealed with a small amount of input heat. In other words, only the desired region can be efficiently heated, and the power consumption for induction heating for annealing can be reduced.

FIG. 5 shows a temperature history when the annealed motor core C is heated by the annealing apparatus 1 according to the present embodiment, specifically, an alternating current is supplied from the AC power source 20 to the inner induction coil 10 for 3 minutes to be annealed motor core. It is a figure which shows temperature history when C is heated and the to-be-annealed motor core C is naturally cooled without performing cooling by the cooling device 11 after that. In FIG. 5, the horizontal axis represents time, and the vertical axis represents temperature.
According to the annealing apparatus 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 increased to 750 to 850 ° C. in a very short time of 3 minutes. Further, since the inside of the annealed motor core C is maintained at 500 ° C. or lower when the temperature is raised, that is, the amount of heat given to the entire annealed motor core C during the annealing is suppressed, the cooling device 11 Even if it does not perform cooling by (3), it can be cooled to 500 ° C. in a very short time of about 8 minutes, and can be cooled in a shorter time by using the cooling device 11.

  Furthermore, in this embodiment, since the penetration depth δ of the induced current by the inner induction coil 10 in the above equation (1) is equivalent to the introduction depth of the strain to be removed by annealing, the strain introduction portion is localized with high efficiency. Can be heated.

  Moreover, in this embodiment, since the cooling device 11 is arranged side by side with the inner induction coil 10 along the axial direction of the annealed motor core C, that is, the moving direction of the annealed motor core C, the cooling by the cooling device 11 is performed. It can be performed following the heating by the inner induction coil 10. Therefore, since the distance between the inner induction coil 10 and the cooling device 11 and the moving distance of the motor core C to be annealed between the inner induction coil 10 and the cooling device 11 can be reduced, the size of the annealing device 1 is increased. Annealing can be completed in a short time without conversion.

  The cooling device 11 is preferably provided at a predetermined position, for example, at a predetermined position where the heating by the inner induction coil 10 can be prevented from being hindered by the cooling by the cooling device 11.

  The coil mounting table 14 and the core mounting table 15 described above constitute a moving mechanism that changes the relative position between the inner induction coil 10 and the motor core C to be annealed and the relative position between the cooling device 11 and the motor core C to be annealed. The movement mechanism of the invention is not limited to this. For example, the axial length of the annealed motor core C in the leg portion 15b of the core mounting table 15 is fixed, the axial length of the leg portion 14b of the coil mounting table 14 is variable, and the annealed motor core C is You may make it move to an axial direction. Further, both the legs 14b and 15b may be variable in length in the axial direction.

In the above example, the cooling medium ejection start timing is when the power supply from the AC power supply 20 is stopped, but is not limited to this example, and the cooling medium ejection is started before the power supply is stopped. It may be.
Moreover, in the above example, the start timing of the power supply from the AC power supply 20 is after the annealed motor core C is opposed to the central portion of the inner induction coil 10 in the axial direction of the annealed motor core C. However, the present invention is not limited to this example, and the power supply may be started before that.

(Second Embodiment)
FIG. 6 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. 7 is an explanatory diagram of a later-described rotation drive unit provided in the annealing apparatus of FIG. 6.
The annealing apparatus 1 of FIG. 6 is provided with a rotation drive unit 30 in addition to the same constituent members as those of the annealing apparatus of the first embodiment.

  The rotation driving unit 30 rotates the core mounting table 15, and includes, for example, a motor or the like, and is provided at the base of the leg portion 15 b that supports the mounting plate 15 a of the core mounting table 15. The rotation axis of the core mounting table 15 is made coincident with the central axis of the motor core C to be annealed, and the core mounting table 15 is rotated by the rotation drive unit 30 to rotate the annealing motor core C around the central axis. Can do. That is, the rotation drive unit 30 also rotates the to-be-annealed motor core C. Further, the rotation axis of the core mounting table 15 is made to coincide with the central axis of the inner induction coil 10 as well as the central axis of the annealed motor core C, and the core mounting table 15 is rotated by the rotation drive unit 30, As shown in FIG. 7, the annealed motor core C can be rotated with respect to the inner induction coil 10. That is, the rotation drive unit 30 can relatively rotate the inner induction coil 10 and the annealed motor core C.

By the way, in 1st Embodiment which does not have a rotation drive part, the magnetic flux which this coil 10 generate | occur | produces in the circumferential direction of the inner induction coil 10, ie, the circumferential direction of the to-be-annealed motor core C, by the winding method of the inner induction coil 10 is not. It may be uniform. In that case, the induced current generated in the annealed motor core C by the magnetic flux becomes non-uniform in the circumferential direction of the annealed motor core C, and as a result, the temperature difference in the circumferential direction of the annealed motor core C heated by the induced current occurs. Will occur.
By providing the rotation drive unit 30 and rotating the inner induction coil 10 and the to-be-annealed motor core C relatively as in the present embodiment, it is possible to prevent the above-described circumferential temperature difference from occurring.

  Note that the rotation speed by the rotation driving unit 30 is a speed that makes at least one rotation during the heating time by the inner induction coil 10, and preferably a speed that makes 10 rotations during the heating time.

(Third embodiment)
FIG. 8 is a longitudinal sectional view showing the outline of the configuration of the annealing apparatus according to the third embodiment of the present invention.
In the annealing apparatus of the first and second embodiments described above, the inner induction coil 10 which is an annular member disposed concentrically with the to-be-annealed motor core C is provided inside the to-be-annealed motor core C. In these embodiments, the to-be-annealed motor core C to be annealed is a stator core, and slots and teeth are formed on the inner periphery thereof.
On the other hand, as shown in FIG. 8, the annealing apparatus 1 according to the present embodiment is an annular member that is arranged concentrically with the to-be-annealed motor core C as an induction coil for heating outside the to-be-annealed motor core C. It has an outer induction coil 40. And the to-be-annealed motor core C which is annealing object is a rotor core, Although illustration is abbreviate | omitted, the slot and teeth are formed in the outer peripheral part. It can be described that the outer induction coil 40 is provided on the outer peripheral side, which is the side facing the slot-formed side, of the outer peripheral side and the inner peripheral side of the annealed motor core C.

  In the present embodiment, the coil mounting table 41 provided in place of the coil mounting table 14 in the first and second embodiments is a coil except that it is provided so as to cover the outside of the core mounting table 15. It has the same configuration as the mounting table 14 and functions similarly.

  In the present embodiment, the cooling device 42 provided in place of the cooling device 11 sprays a cooling medium on the outer peripheral surface of the annealed motor core C heated by the outer induction coil 40, that is, the slot forming surface, and the annealed motor core. C is cooled.

  In the present embodiment, when only the slot forming portion, that is, the outer peripheral portion of the to-be-annealed motor core C, which is a rotor core, needs to be annealed, the outer induction coil 40 disposed outside the to-be-annealed motor core C as described above. Annealing. Therefore, annealing can be performed with a small amount of power and in a short time.

  In addition, in this embodiment, as described above, since the cooling device 42 is provided in addition to the outer induction coil 40 as the heating induction coil, up to a predetermined temperature of the heated portion of the annealed motor core C. The time required for annealing the to-be-annealed motor core C including the cooling of can be greatly shortened.

  Also in the present embodiment, the highest ultimate temperature of the surface layer of the outer peripheral portion that is the strain introduction portion in the annealed motor core C is 750 to 850 ° C., and the highest ultimate temperature inside the annealed motor core C is 500 ° C. or less. By performing induction heating, the strain introduction part can be annealed with a small amount of input heat. Furthermore, also in this embodiment, for example, the frequency of the AC power source is set so that the penetration depth δ of the induced current by the outer induction coil 40 in the above-described equation (1) corresponds to the introduction depth of the strain to be removed by annealing. By selecting, the distortion can be surely removed.

(Fourth embodiment)
FIG. 9: is a longitudinal cross-sectional view which shows the outline of a structure of the annealing apparatus concerning 4th Embodiment of this invention.
The annealing apparatus of the first to third embodiments had either one of the inner induction coil 10 and the outer induction coil 40. On the other hand, the annealing apparatus 1 of this embodiment has both the inner induction coil 10 and the outer induction coil 40 as shown in FIG.

And in the annealing apparatus 1 and annealing method of this embodiment, when the to-be-annealed motor core C which is an annealing object is a stator core in which a slot is formed in the inner peripheral part, the inner induction coil 10 and the outer induction coil 40 Of these, the inner induction coil 10 is used to anneal only the inner peripheral portion that is the slot forming portion of the motor core C to be annealed.
Moreover, in the annealing apparatus 1 and annealing method of this embodiment, when the to-be-annealed motor core C which is an annealing object is a rotor core in which slots are formed on the outer periphery, the inner induction coil 10 and the outer induction coil 40 Among these, the outer induction coil 40 is used to anneal only the outer peripheral portion that is the slot forming portion of the motor core C to be annealed.
Therefore, even with the annealing apparatus 1 and the annealing method of the present embodiment, the same effects as those of the first embodiment and the third embodiment can be obtained.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

(Test Example 1)
As Test Example 1 of the present invention, a simulation was performed on the heat generation density when induction-heated motor core C to be annealed, which is a stator core, using annealing apparatus 1 according to the first embodiment of the present invention. The outer diameter of the motor core C to be annealed was 134 mm, the inner diameter was 67 mm, and the axial thickness was 10 mm. The volume resistivity of the annealed motor core C was 5.2e ⁻⁷ Ω · m in the plane, and the axial direction was infinite. The inner induction coil 10 had an outer shape of 58 mm, a diameter direction thickness of 8 mm, and the axial direction thickness of 17 mm. In addition, the axial center position of the inner induction coil 10 and the axial center position of the annealed motor core C were matched. Further, the inner induction coil 10 is provided with a water cooling pipe, and the inner induction coil 10 is wound around a magnetic core.

  Then, the data shown in FIG. 10 is used for the axial center position at the tip of the teeth portion of the annealed motor core C by changing the frequency of the AC power supply 20 that applies an AC current to the inner induction coil 10 to 1 kHz, 10 kHz, and 50 kHz. Got. The horizontal axis in FIG. 10 is the depth from the surface, and the vertical axis is the heat generation density.

  As shown in FIG. 10, it can be confirmed that the higher the frequency of the AC power supply 20, the lower the heat generation density in the deeper region from the surface due to the skin effect. Therefore, it can be seen 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 20. In addition, since the depth of the strain generated by the punching process of the electromagnetic steel sheet is generally about half of the thickness of the electromagnetic steel sheet, for example, when the thickness of the electromagnetic steel sheet is about 0.35 mm, the result of FIG. For example, if the frequency of the AC power supply 20 is set to approximately 10 kHz or more, heat generation can be concentrated to a depth corresponding to the plate thickness, that is, a distortion depth.

(Test Example 2)
As Test Example 2 of the present invention, the annealing apparatus 1 according to the first embodiment of the present invention was used, the frequency of the AC power supply 20 was 50 kHz, the amperage of the inner induction coil 10 (ampere turn) was 2000 AT, and the stator core A simulation was performed for a temperature history when a certain annealed motor core C was induction-heated. Conditions other than the frequency of the AC power supply 20 and the ampere winding of the inner induction coil 10 were the same as in the simulation of Test Example 1.

FIG. 11 is a diagram showing the temperature history of the center portion of the tip end surface of the tooth portion of the annealed motor core C and the center portion inside the core at the root of the tooth portion in Test Example 2.
As shown in FIG. 11, when induction heating is performed with the frequency of the AC power supply being 50 kHz using the annealing apparatus 1, the tip end surface of the teeth portion of the to-be-annealed motor core C that is the strain introduction portion can be selectively heated.

(Test Example 3)
As Test Example 3 of the present invention, the annealing apparatus 1 according to the first embodiment of the present invention is used, and the induction heating is actually performed until the teeth portion of the motor core C to be annealed reaches 850 ° C. under the same conditions as in Test Example 2. Then, cooling was performed to 200 ° C. by blowing nitrogen gas using the cooling device 11. Note that the test conditions of Test Example 3 differed from Test Example 2 only in the number of ampere turns of the inner induction coil 10, and the number of ampere turns was 1100AT.
Table 1 shows the results of Test Example 3.

  In addition, the comparative example 1 of Table 1 is the same as patent documents 1-4, and the said to-be-annealed motor core is provided with the induction coil provided in the outer side of the to-be-annealed motor core which is a stator core by which the slot was formed in the inner peripheral part. This is an example of heating and then naturally cooling. Further, Comparative Example 2 is an example in which the cooling apparatus 11 is not actively cooled under the same heating conditions as in Test Example 3 and is allowed to cool.

  As shown in Table 1, in Comparative Example 1, the time required to raise the temperature of the teeth portion of the to-be-annealed motor core C from room temperature to 850 ° C. was 1400 seconds at a power output 1 kW of an AC power source for induction heating. The amount of heat input, that is, the power consumption with respect to the temperature rise up to 850 ° C. was 1400 kJ. On the other hand, in Test Example 3, the time required to raise the temperature of the teeth portion of the annealed motor core C from room temperature to 850 ° C. is 100 seconds at the power output of the AC power supply 20 of 5 kW, and the temperature rise to 850 ° C. The input heat amount is 500 kJ, which is about 1/3 that of Comparative Example 1.

Further, as a method of raising the temperature of the teeth portion of the annealed motor core from room temperature to 850 ° C., a method of uniformly heating the entire annealed motor core by an induction heating method is conceivable. However, in this method, even if only the heat capacity of the annealed motor core is considered, in other words, even if it can be heated ideally without loss, the power consumption required to raise the temperature from room temperature to 850 ° C. is 600 kJ. . The power consumption 500 kJ in Test Example 3 is smaller than 600 kJ. That is, in induction heating using the annealing apparatus 1, the teeth of the motor core to be annealed can be heated from room temperature to 850 ° C. with very little power consumption.
Furthermore, paying attention to the cooling time in Table 1, the cooling time of Test Example 3 in which cooling was performed can be about 1/3 of that in Comparative Example 2 in which positive cooling was not performed. The cooling in Comparative Example 1 and Comparative Example 2 is both natural cooling, and the difference in the cooling time is considered to be based on the difference in the amount of heat input to each. As described above, according to the present invention, by combining induction heating using the annealing apparatus 1 and cooling using the cooling apparatus 11, the processing time can be shortened and the productivity can be improved.

  The present invention occurs when a motor core is formed by fixing by crimping, screwing, welding, or the like in a state where a plurality of punched electromagnetic steel sheets are stacked in a state where a plurality of punched electromagnetic steel sheets are laminated. This is useful when annealing the motor core in order to remove the strain.

DESCRIPTION OF SYMBOLS 1 Annealing apparatus 10 Inner induction coil 11 Cooling apparatus 12 Bulkhead for annealing atmosphere adjustment 12a Lid part 12b Bottomed container part 12c Gas supply pipe 13 Heat insulation material 14 Coil mounting table 14a Mounting plate 14b Leg part 15 Core mounting table 15a Mounting Mounting plate 15b Leg 20 AC power supply 30 Rotation drive unit 40 Outer induction coil 41 Coil mounting table 42 Cooling device C Motor core (annealed motor core)
Ca teeth part Cb Back yoke part Cc Slot

Claims (6)

An apparatus for laminating one or more motor cores formed by laminating electromagnetic steel plates after punching,
An annular outer induction coil disposed concentrically with the to-be-annealed motor core on the outside of the one or a plurality of laminated motor cores (hereinafter simply referred to as the to-be-annealed motor core). One or both of the annular inner induction coils arranged concentrically with the to-be-annealed motor core inside the annealing motor core,
An alternating current power source for applying an alternating current to the outer induction coil and / or the inner induction coil;
A cooling device that sprays a cooling medium on the heating portion of the annealing motor core heated by the outer induction coil and / or the inner induction coil, and cools the annealing motor core;
A motor mechanism comprising: a moving mechanism that changes a relative position between the outer induction coil and / or the inner induction coil and the annealed motor core and a relative position between the cooling device and the annealed motor core. Annealing equipment. The apparatus for annealing a motor core according to claim 1, wherein the cooling device is arranged along with the outer induction coil and / or the inner induction coil along an axial direction of the annealed motor core. . The apparatus for annealing a motor core according to claim 1 or 2, wherein the frequency of the alternating current applied by the alternating current power source is 10 kHz or more. A partition for annealing atmosphere adjustment that accommodates the annealing motor core inside,
The apparatus for annealing a motor core according to any one of claims 1 to 3, further comprising a heat insulating material covering an outer side or an inner side of the partition wall. The annealing of the motor core according to any one of claims 1 to 4, 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. apparatus. A motor core annealing method for removing strain introduced into the outer peripheral surface and / or inner peripheral surface of the to-be-annealed motor core using the motor core annealing apparatus according to any one of claims 1 to 5. And
The introduction depth of the strain is associated with the penetration depth δ in the following formula (1), and the motor core is induction-heated by an AC current having a frequency f of an AC power source obtained from the following formula (1). A method for annealing a motor core, wherein the temperature of a slot forming surface of the motor core is raised to 750 to 850 ° C. while suppressing the temperature to 500 ° C. or lower.
δ = 503 × (ρ / (μ · f)) ^1/2 (1)
here,
δ: penetration depth of eddy current causing induction heating ρ: volume resistivity of the motor core
μ: Magnetic permeability of the motor core f: Frequency of AC current applied by the AC power source

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