Press punching device for rotating electrical machine core sheet

Abstract

To easily confirm a parallel state between the surface of a punch plate and the surface of a die plate in a press punching device for a core sheet of a motor core.SOLUTION: In a press punching device, a permanent magnet 2 is fixed to one of the bases at a distance along the periphery of a first base 1 that supports a punch plate 1a and a second base 5 that supports a die plate 5a, and a coil 6 is fixed to the other base in alignment with the position of the permanent magnet. Current detection means 8 is provided to detect the current flowing in each of the coils, and whether the surface direction of the punch plate and the surface direction of the die plate are parallel is determined on the basis of the difference between the current flowing in each of the coils when the first and second bases approach each other and each of the permanent magnets approaches its corresponding coil, and the current flowing when the surface direction of the punch plate and the surface direction of the die plate are parallel.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an apparatus for forming a rotor core and a stator core of a rotating electrical machine by press-punching magnetic steel sheets into laminated core sheets. [Background technology]

[0002] Rotor cores and stator cores (hereinafter referred to as "motor cores") for rotating electrical machines are typically constructed by stacking core sheets formed by press-punching electromagnetic steel sheets. Various technologies have been proposed related to the formation of such core sheets and the construction of the core. For example, Patent Document 1 proposes a technique for adjusting motor core forming conditions without interrupting motor core production. It proposes a method for repeatedly performing a pressing process in which core sheets formed by press-punching are stacked and dowel-stitched to form a motor core, and a measurement process in which the parallelism of the formed motor core is measured. In the pressing process performed after the measurement process, the pressing amount by the press die and the number of laminated electromagnetic steel sheets can be changed based on the parallelism measured in the measurement process. Patent Document 2 proposes a method for improving the processing accuracy of laminated electromagnetic steel sheets by passing a shaft member held in a press device through holes formed in the steel sheets that extend in the stacking direction, thereby pressing the steel sheets using the press device while the steel sheets are fixed to the shaft member. Although not related to a press punching device for forming a core sheet, Patent Documents 3 and 4 propose a configuration in which the parallelism between the upper and lower dies of a press device is adjusted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-54225 [Patent Document 2] Patent Publication No. 2019-75935 [Patent Document 3] Patent Publication No. 2012-125810 [Patent Document 4] Patent Publication No. 2017-13071 Summary of the Invention [Problem to be solved by the invention]

[0004] In press punching of core sheets for motor cores, it is preferable to obtain high dimensional accuracy and high productivity. In particular, in a press machine, if the surfaces of the punch plate and the die plate that sandwich the electromagnetic steel sheets that form the core sheet are inclined (deviation) from their parallel state, there is a high possibility that peeling will occur between the sheets when the stacked core sheets are fastened by crimping. Therefore, it is preferable to be able to easily check, at any time, whether the deviation from parallelism between the surfaces of the punch plate and the die plate is within an allowable range. In relation to this point, in the past, as shown in FIG. 4, end blocks 14 were provided on both edges of a punch plate surface 10 and a die plate surface 12 so as to face each other, and the parallel state of the punch plate and die plate surfaces was confirmed for each press by the end blocks simultaneously coming into contact with each other at the bottom dead center where the punch plate surface and the die plate surface come close to each other. However, at the bottom dead center, the punch plate may bend (w) or the end blocks may wear due to repeated contact (f), making it difficult to accurately confirm the parallel state. In addition, there was a cumbersome need to adjust the height of the end blocks in accordance with variations in the thickness of the electromagnetic steel sheet.

[0005] In view of the above circumstances, the main object of the present invention is to provide a configuration in a core sheet press punching device that can easily confirm the parallel state between the punch plate surface and the die plate surface without using end blocks on the punch plate and the die plate. [Means for solving the problem]

[0006] According to the present invention, the above-mentioned object can be achieved by providing a press punching apparatus having a first base supporting a punch plate and a second base supporting a die plate disposed opposite to the punch plate, the press punching apparatus punching core sheets to be laminated to form a motor core from electromagnetic steel sheets transported between the punch plate and the die plate, a plurality of pairs of permanent magnets and coils are arranged at intervals along the periphery of the first and second bases, with the permanent magnets fixed to one of the first and second bases and the coils fixed to the other of the first and second bases in alignment with the positions of the permanent magnets; a current detection means for detecting a current flowing through each of the coils; and determining whether the surface direction of the punch plate and the surface direction of the die plate are parallel based on a difference between a current flowing in each of the coils when the first and second bases approach each other and each of the permanent magnets approaches a corresponding one of the coils and a current flowing when the surface direction of the punch plate and the surface direction of the die plate are parallel. This is achieved by:

[0007] In the above configuration, the press punching device may have, in a conventional manner, first and second bases each supporting a punch plate and a die plate for punching a core sheet to be stacked to form a motor core, and when an electromagnetic steel sheet is transported between the punch plate and the die plate, the first and second bases approach each other, and the punch plate presses the electromagnetic steel sheet against the die plate to punch out the electromagnetic steel sheet in a pattern pre-configured on the die plate to form a core sheet. In such a configuration, as described above, a plurality of pairs of permanent magnets and coils are arranged at intervals that may be appropriately set along the outer periphery of the first and second bases, where a permanent magnet is fixed to one of the first and second bases and a coil is fixed to the other of the first and second bases in alignment with this position. In this configuration, a plurality of permanent magnets may be fixed to the first base, and a plurality of coils may be fixed to the second base in alignment with each of the permanent magnets. Alternatively, a plurality of coils may be fixed to the first base, and a permanent magnet may be fixed to the second base in alignment with each of the coils. Alternatively, a permanent magnet and a coil may be fixed to the first base, and a coil and a permanent magnet may be fixed to the second base in alignment with each of the coils. In this case, when the first base and the second base approach each other, the permanent magnets will be close to each coil, and current will flow through the coil. Therefore, in the present invention, as described above, whether the surface direction of the punch plate and the surface direction of the die plate are parallel is determined based on the difference between the current flowing in each coil when the first and second bases approach each other and each permanent magnet approaches its corresponding coil, and the current flowing when the surface direction of the punch plate and the surface direction of the die plate are parallel. The current detection means may be an ammeter or the like that can detect the current flowing through any type of coil.

[0008] According to the above-described configuration of the present invention, each time the first and second bases move toward and away from each other to punch an electromagnetic steel sheet, the permanent magnet moves toward and away from the coil that is aligned with it, and so current flows through the coil. However, if the surface of the die plate is tilted relative to the surface of the punch plate and the parallel state of the two surfaces is lost, the current will flow differently from when the surfaces of the punch plate and the die plate are parallel, and thus it is possible to easily confirm whether the surface of the punch plate and the surface of the die plate are maintaining a parallel state during punching of an electromagnetic steel sheet.

[0009] In the above-described configuration of the present invention, preferably, if the surface direction of the punch plate and the surface direction of the die plate are parallel, i.e., if there is no inclination between the surfaces of the punch plate and the die plate, the pairs of permanent magnets and coils may be adjusted so that equal currents flow through all of the coils when the first and second bases approach each other and each permanent magnet approaches its corresponding coil. The adjustment of the pairs of permanent magnets and coils involves appropriately adjusting specifications such as the magnetic force of the permanent magnets and the number of turns and size of the coils. With this configuration, if the surface of the die plate is inclined relative to the surface of the punch plate and the parallelism between the two surfaces is lost, the currents flowing through the coils will differ. This makes it easier to confirm whether the surface of the punch plate and the surface of the die plate are maintained parallel during punching of an electromagnetic steel sheet.

[0010] In the above configuration, the difference in current flowing in each coil or the difference in current flowing between the coils increases in accordance with the magnitude of the inclination of the die plate surface relative to the punch plate surface. Therefore, when a difference in current corresponding to an unacceptable magnitude of the inclination of the die plate surface relative to the punch plate surface is detected, the punching process of the electromagnetic steel sheet may be interrupted and the inclination of the die plate surface relative to the punch plate surface may be adjusted. [Effects of the Invention]

[0011] According to the above-described configuration of the present invention, in a core sheet press-punching device, by monitoring the current difference between coils fixed to one of the bases supporting the punch plate and the die plate, respectively, it is possible to easily confirm the parallel state of the punch plate surface and the die plate surface without contacting the punch plate and the die plate. With this configuration, if the parallel state of the punch plate surface and the die plate surface is lost, this can be immediately detected, and in that case, the press-punching of the core sheet can be interrupted and the inclination of the punch plate surface and the die plate surface can be adjusted. This makes it possible to form a core sheet so that the dimensional accuracy of the formed core sheet falls within an acceptable range, and it is expected that press-punching of a core sheet can be performed with high dimensional accuracy and high productivity.

[0012] Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention. [Brief explanation of the drawings]

[0013] [Figure 1] 1A is a schematic side view and a bottom view of a first base supporting a punch plate of a press punching device to which this embodiment is applied, and FIG. 1B is a schematic top view and a side view of a second base supporting a die plate. [Figure 2] FIG. 2(A) is a schematic side view of the press punching device of this embodiment in a state where the first base supporting the punch plate is at the top dead center, and FIG. 2(B) is a schematic side view of the press punching device of this embodiment in a state where the first base supporting the punch plate is at the bottom dead center. [Figure 3] Figure 3(A) shows the change in coil current over time when the punch plate surface and the die plate surface are kept parallel, and Figure 3(B) shows the change in coil current when the punch plate surface and the die plate surface are no longer parallel. [Figure 4]FIG. 4(A) is a schematic side view of a press punching device in which end blocks are provided on the edges of a conventional punch plate and a die plate, with the first base supporting the punch plate at the top dead center, and FIG. 2(B) is a schematic side view of the press punching device of this embodiment, with the first base supporting the punch plate at the bottom dead center. [Explanation of symbols]

[0014] REFERENCE SIGNS LIST 1...first base, 1a...punch plate, 2...permanent magnet, 5...second base, 5a...die plate, 6...coil, 8...ammeter, 10...punch plate, 12...die plate, 14...end block BEST MODE FOR CARRYING OUT THE INVENTION

[0015] The present invention will now be described in detail with reference to some preferred embodiments thereof with reference to the accompanying drawings, in which like reference numerals indicate like parts.

[0016] 1(A) and 1(B), permanent magnets 2 and coils 6 are fixed along the outer peripheries of a first base 1 supporting a punch plate 1a and a second base 5 supporting a die plate 5a at appropriate intervals and in aligned positions. While the permanent magnets 2 are fixed to the first base 1 and the coils 6 are fixed to the second base 5 in the figure, the coils 6 may be fixed to the first base 1 and the permanent magnets 2 may be fixed to the second base 5. Alternatively, the permanent magnets 2 and coils 6 may not be fixed to the same position on the first base 1 and the second base 5 as long as one coil 6 faces one permanent magnet 2. An ammeter 8 is connected to each of the coils 6 to detect the current flowing through them.

[0017] When the first base 1 and the second base 5 are in use, as shown in FIG. 2(A), the punch plate 1a and the die plate 5a are arranged so that they face each other, and one coil 6 faces each permanent magnet 2, with its central axis passing through the permanent magnet 2. When punching a core sheet, an electromagnetic steel sheet (not shown) is transported between the punch plate 1a and the die plate 5a, and the punch plate 1a and the die plate 5a are brought close to each other, as shown in FIG. 2(B). As a result, the permanent magnets 2 approach each coil 6, and current flows through each coil 6. In this regard, if the surface directions of the punch plate 1a and the die plate 5a deviate from a parallel state, the current flowing through each coil 6 changes. Therefore, based on the difference in current, it is possible to determine whether the surface directions of the punch plate 1a and the die plate 5a are parallel to each other.

[0018] More preferably, the specifications of the permanent magnet 2 and the coil 6 arranged along the outer periphery of the first base 1 and the second base 5 may be adjusted so that the currents flowing through the coil 6 are equal when the surface direction of the punch plate 1a and the surface direction of the die plate 5a are parallel and the first base 1 and the second base 5 approach each other. In such adjustments, the magnetic force of the permanent magnet 2, the number of turns of the coil 6, the diameter, etc. may be adjusted as appropriate.

[0019] When the permanent magnets 2 and coils 6 are adjusted as described above, the punch plate 1a and the die plate 5a repeatedly move close to and away from each other to continuously punch out the core sheet, and as long as the surface directions of the punch plate 1a and the die plate 5a are parallel, the currents I flowing through each coil 6 detected by the ammeter 8 will increase and decrease in unison, as shown in Figure 3(A). In this figure, T is time, b is the time when the punch plate 1a and the die plate 5a are at their closest bottom dead center (Figure 2(B)), and u is the time when the punch plate 1a and the die plate 5a are at their furthest top dead center (Figure 2(A)).

[0020] On the other hand, when the surface directions of the punch plate 1a and the die plate 5a become deviated from parallel, the current flowing through each coil 6 deviates as the punch plate 1a and the die plate 5a approach and move away from each other, as shown in FIG. 3(B). The deviation in the current flowing through each coil 6 increases with the magnitude of the deviation from parallelism between the surface directions of the punch plate 1a and the die plate 5a. Therefore, in this embodiment, the current of each coil 6 is continuously monitored by the ammeter 8. When the deviation in the current reaches a limit corresponding to the allowable deviation from parallelism between the surface directions of the punch plate 1a and the die plate 5a, it is determined that adjustment of the surface directions of the punch plate 1a and the die plate 5a is necessary, and punching of the core sheet may be stopped.

[0021] According to the above-described configuration, it is easy to constantly monitor the degree of parallelism between the surface directions of the punch plate 1a and the die plate 5a, and when the inclination between the surface directions of the punch plate 1a and the die plate 5a reaches an allowable limit, this can be immediately detected. Therefore, it is expected that high dimensional accuracy and high productivity can be achieved in the punching process of the core sheet.

[0022] The above description has been made in relation to the embodiments of the present invention, but it will be apparent that many modifications and changes will be readily apparent to those skilled in the art, and the present invention is not limited to the above-described exemplary embodiments, but can be applied to various devices without departing from the concept of the present invention.

Claims

[Claim 1] A press punching apparatus comprising: a first base supporting a punch plate; and a second base supporting a die plate disposed opposite the punch plate; the press punching apparatus punches core sheets to be laminated to form a motor core from electromagnetic steel sheets transported between the punch plate and the die plate; a plurality of pairs of permanent magnets and coils are arranged at intervals along the periphery of the first and second bases, with the permanent magnets fixed to one of the first and second bases and the coils fixed to the other of the first and second bases in alignment with the positions of the permanent magnets; a current detection means for detecting a current flowing through each of the coils; The device is configured to determine whether the surface direction of the punch plate and the surface direction of the die plate are parallel based on a difference between the current flowing in each of the coils when the first and second bases approach each other and each of the permanent magnets approaches the corresponding coil, and the current flowing when the surface direction of the punch plate and the surface direction of the die plate are parallel.

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