JP2011087360A - Manufacturing method of steel plate having non-magnetic point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a steel plate having a non-magnetic point, which forms a desired non-magnetic point by surely heating the plate by electricity carrying and heating without the need for the processing extremely high in precision. <P>SOLUTION: In the manufacturing method, a reformed substance 21 is sandwiched between two electromagnetic steel plates 11A, 11B, the reformed substance is melted together with steel at its circumference, and an austenite phase is partially generated. The manufacturing method has: a sandwiching process in which the two electromagnetic steel plates on which recessed grooves 12A, 12B are formed, respectively, are overlapped with each other while making the recessed grooves oppose each other, and the reformed substance is inserted to a space which is formed of the opposing recessed grooves; a small-electricity carrying process which applies currents to the two electromagnetic steel plates and the reformed substance in a range smaller than a plane shape of the reformed substance out of points into which the reformed substances are inserted, respectively; and a large-electricity carrying process which applies currents to the two electromagnetic steel plates and the reformed substance in a range larger than the plane shape of the reformed substance out of the points into which the reformed substances are inserted, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a steel plate for forming a partial nonmagnetic region in a magnetic member such as an electromagnetic steel plate. More specifically, the present invention relates to a method for producing a steel sheet having a non-magnetic part by placing a modifying substance in the steel sheet and heating and melting it to make the part a nonmagnetic austenite structure.

  Conventionally, there is a technique for forming a nonmagnetic portion by partially generating an austenite phase on a magnetic member such as iron. For example, Patent Document 1 discloses a technique in which a modifying element is added to a portion to be demagnetized, and the solution is locally heated to form a solid solution. Patent Document 2 discloses a technique in which a material containing an element that generates an austenite phase is applied to a steel material, melted together with iron by heating, and alloyed to form a nonmagnetic portion. This technique can be applied to, for example, a rotor of a rotating electrical machine or a core of a stator. Since there are places in the core that do not become effective magnetic flux paths, they are made non-magnetic.

JP 2001-93717 A JP 2008-99360 A

  For example, when the above technique is applied to a core made of laminated steel sheets in which a large number of electromagnetic steel sheets are laminated, two steel sheets with grooves are facing each other, and the modification material is sandwiched between the grooves and heated. A method is conceivable. There is also a method of using Joule heat by energization by sandwiching two steel plates with electrodes from the outside for heating. Then, the portion can be made non-magnetic by melting the reforming substance and alloying it with the steel plate.

  When the heating method using Joule heat is adopted, it is necessary to form a current path that appropriately passes through the modifying substance. However, the thickness of the modifying substance may be slightly smaller than the total thickness of the concave grooves formed by cutting in the steel plate. If there is a gap between the sandwiched reforming material and the steel plate, the contact area between the steel plates 101 and 102 and the reforming material 103 is very small as shown in the left diagram of FIG. There is a possibility that the contact is made only at the end portion of the reforming substance 103.

  When current is passed between the electrodes 111 and 112 in this state, as shown in the center diagram of FIG. Current may not flow. In that case, only the end portion of the reforming substance 103 is particularly heated, as indicated by dot hatching in the right diagram of FIG. In the center, there is a problem in that it is not sufficiently demagnetized due to insufficient melting, and a thin demagnetized region 115 in the center is formed as shown in FIG.

  Of course, it is possible in principle to perform very precise processing to prevent gaps. However, this increases costs and processing time, and is not realistic. In the core, since it is required to form a plurality of non-magnetic portions on each of a large number of laminated steel plates, it is desirable that the processing can be performed in a short time and at a low cost.

  The present invention has been made to solve the problems of the above-described conventional steel plate manufacturing methods. That is, the subject is to provide a method of manufacturing a steel sheet having a non-magnetic part that can be reliably heated by energization heating to form a desired non-magnetic part without performing very precise processing. There is.

  In order to solve this problem, the method of manufacturing a steel sheet having a non-magnetic portion according to the present invention includes a method in which a modifying material is sandwiched between two electromagnetic steel sheets, and the modifying material is melted together with the surrounding steel to partially A method for producing a steel sheet having a non-magnetic portion by generating an austenite phase, wherein two electromagnetic steel sheets each having a concave groove are used. , The process of sandwiching the modifying material in the space formed by facing the grooves and facing each other, and the range where the modifying material is inserted is smaller than the planar shape of the modifying material A small energization process in which current is applied to the two electrical steel sheets and the reforming material, and two sheets within the range where the reforming material is inserted in the area where the reforming material is inserted after the small energization process. Electrical steel sheet and modification Those having a large current supply step of applying a current to the quality.

  According to the manufacturing method of the present invention, Joule heat can be generated and melted by energizing with the modifying material sandwiched between the concave grooves of the two electromagnetic steel sheets. At that time, since a small energization process is first performed, it is possible to reliably energize within the range of the planar shape of the reforming substance, and to easily energize the portion. After that, the large energization process is performed, so that it is possible to reliably energize portions that are easily energized in the small energization process. Thereby, for example, only the end portion of the modifying substance does not melt, and the entire modifying substance can be reliably melted. Therefore, it is a manufacturing method capable of forming a desired nonmagnetic portion by reliably heating by energization heating without performing very precise processing.

Furthermore, in the present invention, it is desirable to apply a current within a range of 1/10 to 2/3 of the amount of current applied in the large energization process in the small energization process.
If the current applied in the small energization process is too small, the formation of a current path for flowing current in the large energization process is insufficient. Moreover, it is a waste of energy that the current applied in the small energization process is too large.

Furthermore, in the present invention, in the large energization process, electricity is applied to the electrodes in contact with the two electrical steel sheets within the range of the planar shape of the reforming substance, and in the small energization process, two sheets are smaller than the planar shape of the reforming substance. It is desirable to energize with an electrode in contact with the electromagnetic steel sheet.
In this way, the reforming substance can be reliably energized within a relatively narrow range in the small energization process. On the other hand, in the large energization process, since the entire reforming substance can be energized, the entire reforming substance can be melted.

Furthermore, in the present invention, it is desirable that the radius of curvature of the tip surface of the electrode used in the small energization step is 1/20 or less of the radius of curvature of the tip surface of the electrode used in the large energization step.
If the radius of curvature of the tip surface of the electrode is small, the contact area with the steel plate is also small. Therefore, it is easy to energize in a small range.

Further, in the present invention, in the small energization process, the two electromagnetic steel sheets are pressed between the two electrodes by pressing the two electromagnetic steel sheets between the two electrodes from the outside, so that the two electromagnetic steel sheets are in close contact with the modifying substance at a location between the two electrodes. It is desirable to energize in such a state.
In this way, it is possible to reliably energize a desired portion of the modifying material.

  According to the method for manufacturing a steel sheet having nonmagnetic portions of the present invention, a desired nonmagnetic portion can be formed by reliably heating by energization heating without performing very precise processing.

It is process drawing which shows the manufacturing method of this form. It is explanatory drawing which shows a groove | channel formation process. It is explanatory drawing which shows a clamping process. It is sectional drawing which shows the mode of the clamped steel plate. It is explanatory drawing which shows a small electricity supply process. It is sectional drawing which shows the mode of the steel plate with small electricity supply. It is explanatory drawing which shows a large electricity supply process. It is sectional drawing which shows the mode of the steel plate which carried out the big electricity supply. It is explanatory drawing which shows the electromagnetic steel plate in which the nonmagnetic location was formed. It is a graph which shows the result of experiment. It is sectional drawing which shows the example of the steel plate manufactured by the Example. It is explanatory drawing which shows the example of the current pathway by the conventional manufacturing method. It is sectional drawing which shows the example of the steel plate manufactured by the conventional manufacturing method.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a method of partially forming a nonmagnetic portion in a magnetic material.

  In this embodiment, for example, a nonmagnetic portion is formed in a part of a laminated steel plate used for a rotor or a stator core. In the present embodiment, a method is adopted in which a modified tip is sandwiched between two steel plates and energized and heated by Joule heat. The steel sheet is an electromagnetic steel sheet that has been widely used. The modified tip contains Cr, Ni, etc., and generates an austenite phase by melting and alloying with the magnetic steel sheet.

As shown in FIG. 1, the manufacturing method of this embodiment is based on the following steps.
(1) Groove forming step; concave grooves are formed at locations of two steel sheets facing each other.
(2) Clamping step: Two steel plates are stacked with the modified chip sandwiched so as to enter the concave groove formed in the groove forming step.
(3) Small energization process: A small electrode is brought into contact with the modified tip and energized with a small current.
(4) Large energization process: A large electrode is brought into contact with the modified tip and energized with a large current.
(5) Electrode separation step: When the temperature of the steel sheet decreases, the electrode is separated.

  Each of these steps will be described in turn. (1) In the groove forming step, as shown in FIG. 2, a concave groove 12 having the same planar shape as that of the modified tip (see FIG. 3) is formed in a part of the steel plate 11. The depth of the concave groove 12 is about half of the thickness of the steel plate 11. Here, since the disk-shaped chip is used as the modified chip, the planar shape of the groove 12 is circular. This forming method may be performed by cutting. Therefore, there may be some size error within the range of cutting accuracy.

  (2) In the sandwiching step, as shown in FIG. 3, the two steel plates 11A and 11B in which the concave grooves 12 are formed by (1) are faced to each other with the concave grooves 12A and 12B facing each other. The modified chip 21 is sandwiched. That is, the steel plate 11B, the modified tip 21, and the steel plate 11A are stacked in this order from the bottom so that the modified tip 21 enters the concave grooves 12A and 12B on both sides.

  Here, the thickness of the modified tip 21 may be slightly thinner than the total depth of the concave grooves 12A and 12B. In that case, as shown in FIG. 4, there may be a slight gap 27 between the surface of the modified tip 21 and the bottom surface of the groove 12A or 12B. Of course, this figure is very exaggerated.

  Next, (3) in the small energization process, as shown in FIG. 5, the small electrode 31A is opposed to a location that hits the upper side of the concave groove 12A of the steel plate 11A and a location that hits the lower side of the concave groove 12B of the steel plate 11B. , 31B abut and pressurize with appropriate pressure. Thereby, (2) Even if the gap 27 is formed at the time of the clamping step, the steel plates 11A and 11B on both sides are bent and contacted with the modified tip 21 at the place where the small electrodes 31A and 31B are in contact. . This figure is also drawn quite exaggeratedly.

  In addition, as the small electrodes 31A and 31B, those having a contact range of the tip portion with the steel plate smaller than the size (planar shape) of the modified tip 21 are used. That is, the range where the small electrodes 31A and 31B are in contact with the steel plates 11A and 11B is within the range where the reforming tip 21 is buried.

  And in the state which contacted the small electrodes 31A and 31B in this way, as shown in FIG. 5, it supplies with electricity between these. The amount of current flowing at this time (current value × energization time) is smaller than the current required for proper reforming. The current required for the reforming is the amount of current that can melt the entire reforming tip 21 and solid-dissolve the surrounding steel plate portion to form a nonmagnetic portion within an appropriate range. This is appropriately selected in advance by experiment according to the size and material of the modified tip 21, the thickness of the steel plate, and the like. This amount of current is also the amount of current supplied in the large energization process described later.

  Part of the modified tip 21 is melted by Joule heat generated by energization in the (3) small energization process. However, at this level of current, not all of the modified tip 21 is melted, but a portion that has not yet melted remains. However, at least the vicinity of both surfaces of the central portion of the modified tip 21 (portions close to the locations where the small electrodes 31A and 31B are disposed) is melted by this process.

  Furthermore, as shown in FIG. 6, in this range, the reformed portion 29 is formed in a small range although it is somewhat dissolved together with the bottom surfaces of the nearby concave grooves 12 </ b> A and 12 </ b> B. Within the range of the reforming portion 29, the reforming tip 21 and the concave grooves 12A and 12B are surely in contact with each other. This contact state is maintained even after the small electrodes 31A and 31B are separated from the steel plates 11A and 11B.

  It is preferable that the current value to be energized in this (3) small energization process is about 1/10 to 2/3 as compared with the amount of current necessary for appropriate reforming. For example, when the energization times are equal, the current value is set to about 1/10 to 2/3. Alternatively, the current values may be equal and the energization time may be about 1/10 to 2/3. (3) If the amount of current energized in the small energization process is smaller than 1/10 of the amount of current required for reforming, the reforming section 29 is not properly formed. In this case, the formation of a current path in a large energization process described later is insufficient. Moreover, (3) It is not preferable that the amount of current to be energized in the small energization process is a waste of energy.

  Next, (4) in the large energization process, as shown in FIG. 7, large electrodes 33A and 33B are arranged and pressurized. The large electrodes 33A and 33B are selected so that the contact range of the tip portion with the steel plate includes at least the entire range in which the modified tip 21 is buried. Furthermore, it is preferable that the contact is made slightly outside the range of the modified tip 21. As described above, an amount of current necessary for appropriate reforming is passed between the large electrodes 33A and 33B.

  (4) The large electrodes 33A and 33B used for energization in the large energization process have (3) the radius of curvature of the tip portion is considerably larger than the small electrodes 31A and 31B used for energization in the small energization process. Should be used. For example, it is desirable that the curvature radii of the small electrodes 31A and 31B be 1/20 or less of the curvature radii of the large electrodes 33A and 33B. By doing in this way, (3) The contact area of the small electrodes 31A, 31B to the steel plates 11A, 11B in the small energization process can be made smaller than that in the (4) large energization process, and only in a small range. It is easy to pass a current through.

  The reformed portion 29 is partially formed by energization in the pre-process (3) small energization step, and the reformed tip 21 and the grooves 12A and 12B are reliably in contact with each other at least in the reformed portion 29. It has become a state. Therefore, the current applied in this step surely flows at least in the central portion. Further, as described in FIG. 12 as the current path according to the conventional technique, the peripheral portion of the reforming chip 21 is originally a portion where current easily flows. As a result, a current is applied to the entire range of the modified chip 21, and the entire modified chip 21 is heated. As a result, as shown in FIG. 8, the reforming tip 21 is reliably melted throughout, and is solid-solved with the surrounding steel plates 11 </ b> A and 11 </ b> B, thereby forming a melted portion 36.

  Then, (5) in the electrode separation step, the large electrodes 33A and 33B are separated from the steel plates 11A and 11B. Thereby, as shown in FIG. 9, the nonmagnetic location 37 is formed. The formed nonmagnetic portion 37 is larger than the range originally occupied by the modified tip 21. This concludes the description of the manufacturing method of this embodiment.

  The present inventors verified the present invention through experiments and confirmed its effects. The result will be described. In this experiment, a non-magnetic portion was partially formed on a steel plate by two types of methods, an example and a comparative example, and the state of the cross section was observed. In the examples, all the steps (1) to (5) of this embodiment were performed. In the comparative example, among the above steps, (3) the small energization step was not performed. All other steps were the same as in the examples.

  In this experiment, a Nichrome (Ni—Cr) chip having an outer diameter of 3 mm and a plate thickness of 0.3 mm was used as the modified chip 21. The electromagnetic steel plates 11A and 11B were each formed with concave plates 12A and 12B having a diameter of 3 mm and a depth of 0.15 mm on a plate having a thickness of 0.3 mm. The set machining accuracy was within the range of ± 0.005 mm for the modified tip 21 and ± 0.015 mm for the depth of the concave grooves 12A and 12B.

  (3) In the small energization process, a Cr-Cu electrode having a spherical shape with a radius of 40 mm is used as the small electrodes 31A and 31B, and the current is 4 kA and the energization time is 0.15 seconds while being pressed with a load of 2 kN Energized. In addition, (4) in the large energization process, a Cr-Cu electrode having a spherical shape with a radius of 1000 mm at the tip is used as the large electrodes 33A and 33B. Was energized. In addition, the contact range of the small electrodes 31A and 31B to the magnetic steel plates 11A and 11B during the pressure contact was about φ1.8 mm. The contact area of the large electrodes 33A, 33B with the electromagnetic steel plates 11A, 11B during the pressure contact was about φ4 mm.

  The result of the experiment was as shown in FIG. Ten examples and comparative examples were manufactured at a time, and the reforming rates were compared based on the cross-sectional state of the non-magnetic portions. As shown in FIG. 11, the reforming rate is determined by the thickness R and the thickness D (the thicknesses of the steel plates 11A and 11B) at the central portion of the nonmagnetic portion 37 (alloy layer of the reforming tip 21 and the steel plates 11A and 11B). The ratio was calculated with That is, the reforming rate = 100 × R / D (%). In this embodiment, it is preferable that the reforming rate exceeds 60%.

  FIG. 11 is an example of a cross section of the structure manufactured according to this example. Fe of the magnetic steel sheet could be taken in a wide range into the nonmagnetic portion 37, and a sufficiently modified portion was formed. On the other hand, what was manufactured by the comparative example contained what the cross-sectional shape was modified | reformed to the shape as shown in FIG. 13 as mentioned above. Due to the presence of the gap 27 (see FIG. 4), it is considered that a modified portion having such a shape is formed as a result of current hardly flowing in the central portion and current flowing concentrated on the end portion. In this example, the modified thickness R at the center is small, and is only about the same as the original modified chip 21 thickness. That is, in the central part, Fe of the electromagnetic steel sheet cannot be taken into the nonmagnetic portion 37.

  From the results of this experiment, as shown in FIG. 10, all the products manufactured by this example were good with the reforming rate exceeding 60%. On the other hand, since the products shown in FIG. 13 were mixed according to the comparative example, the variation in the reforming rate was large. Further, as shown in FIG. 10 by enclosing with a one-dot chain line, an unpreferable range of product has been produced. Therefore, according to the production method of this example, it was confirmed that stable and good modification could be performed.

  As described in detail above, according to the manufacturing method of the present embodiment, the steel plates 11A and 11B having the concave grooves 12A and 12B are faced to each other, and the modified tip 21 is sandwiched between them and heated by energization. Furthermore, a small energization process is first performed, a current path is secured, and then a large energization process is performed. Since at least the central portion of the modified tip can be brought into contact with the steel plate by the small energization process, the current can be appropriately supplied over the entire range of the reforming tip 21 in the large energization step. Accordingly, the entire modified tip 21 can be appropriately melted to reliably form a nonmagnetic portion. Thus, the manufacturing method is capable of forming a desired non-magnetic portion by reliably heating by energization heating without performing particularly precise processing.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
Here, the non-magnetic portion is described as being formed between two steel plates, but a steel plate in which a through hole having the same shape as the modified tip is further sandwiched, and a combination of three or more steel plates may be used. . Further, the shape and thickness of the steel plate, the shape and thickness of the modified tip, the shape of the electrode, etc. are not limited to those described above, and can be appropriately adjusted. In addition, (3) the state of the steel sheet after the small energization step does not have to be the reforming portion 29 as shown in FIG. That is, it is not necessary that the presence of the modified portion 29 is clearly seen on the cross-sectional view.

11A, 11B Steel plate 12A, 12B Groove 21 Modified tip 31A, 31B Small electrode 33A, 33B Large electrode 37 Non-magnetic part

Claims (5)

In a method of manufacturing a steel sheet having a non-magnetic part by sandwiching a modifying substance between two electromagnetic steel sheets and melting the modifying substance together with the surrounding steel to partially generate an austenite phase,
As the two electromagnetic steel sheets, ones each having a concave groove are used, and the two magnetic steel sheets are overlapped with the concave grooves facing each other, and the concave grooves face each other. A sandwiching step of sandwiching the modifying substance in the space;
A small energizing step of applying a current to the two electrical steel sheets and the modifying material in a range smaller than the planar shape of the modifying material among the places where the modifying material is inserted;
After the small energization step, a large energization step of applying a current to the two electrical steel sheets and the reforming material within a range of the planar shape of the reforming material among the portions where the modifying material is inserted The manufacturing method of the steel plate which has a nonmagnetic location characterized by having. In the manufacturing method of the steel plate which has a nonmagnetic location of Claim 1,
In the said small electricity supply process, the electric current in the range of 1/10-2/3 of the electric current amount applied in the said large electricity supply process is applied, The manufacturing method of the steel plate which has a nonmagnetic location characterized by the above-mentioned. In the manufacturing method of the steel plate which has a nonmagnetic location of Claim 1,
In the large energization step, energization is performed with an electrode in contact with the two electromagnetic steel sheets within a range of the planar shape of the modifying substance.
In the said small electricity supply process, it supplies with the electrode which contacts the said 2 electromagnetic steel plate in the range smaller than the planar shape of the said modification | reformation substance, The manufacturing method of the steel plate which has a nonmagnetic location characterized by the above-mentioned. In the manufacturing method of the steel plate which has a nonmagnetic location of Claim 3,
The radius of curvature of the tip surface of the electrode used in the small energization step is 1/20 or less of the radius of curvature of the tip surface of the electrode used in the large energization step. Production method. In the manufacturing method of the steel plate which has a nonmagnetic location of Claim 3,
In the small energization step, the two electromagnetic steel plates are pressed between the two electrodes from outside to press the two electromagnetic steel plates in close contact with the modifying substance at a location between the two electrodes. The manufacturing method of the steel plate which has a nonmagnetic location characterized by supplying with electricity in the made state.

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