JP5878031B2 - Wire rod manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a wire, a wire, a coil formed using the wire, and a stator. In detail, it is related with the manufacturing method etc. of a wire provided with insulation coating with uniform thickness.

  For example, a coil used for a stator or the like constituting an electric motor is formed by providing an insulating coating on the outer peripheral surface of a wire material made of a conductive material such as copper. Conventionally, the insulating coating is formed by applying a liquid obtained by dissolving a thermosetting resin material in a solvent to the outer peripheral surface of the wire material and then curing it by heat treatment.

  The thermosetting resin material that has been applied to the outer peripheral surface of the wire material and has lost the solvent is once softened by the heat treatment, and then the curing reaction proceeds to be cured to form an insulating coating. However, when softened by heat treatment, the influence of surface tension and gravity increases and the thermosetting resin flows. For this reason, when it is going to harden the coating film with large thickness, even if the thickness of a coating film is constant, it is difficult to harden | cure while maintaining the said thickness. Therefore, it is not possible to form an insulating coating having a uniform thickness.

  In particular, when an insulation coating having a required thickness is provided on a wire material having a rectangular cross-section, the corner coating material flows to adjacent sides as shown in FIG. On the other hand, the thickness of the insulating coating in the vicinity of the corners on each side increases, and there is a problem that a uniform insulating coating cannot be formed around the rectangular cross section.

  Conventionally, in order to avoid the above problem, an insulating coating having a required thickness and a uniform thickness is formed by repeating a process of forming a thin coating layer followed by heating and curing a plurality of times. .

JP 2010-287576

  For example, in recent years, in the field of equipment using a coil such as an electric motor, output improvement and downsizing have been demanded. In order to meet the above requirements, it is conceivable to apply a large voltage and a large voltage to each coil. Since the coil is formed by winding a winding formed of a conductive wire such as copper adjacent to each other, it is necessary to ensure insulation between the adjacent windings. For this reason, the insulation coating is formed in the coil outer peripheral surface by predetermined thickness.

  However, as described above, if an insulating coating with a large thickness is formed in a single coating process, an insulating coating with a uniform thickness cannot be formed, and the required insulating performance cannot be ensured. Therefore, in order to form an insulating coating having a large thickness with high insulation performance and a uniform thickness, there is a problem that the number of repetitions of the coating process-curing process increases, and the manufacturing cost increases.

  Further, in order to meet the demand for improving the output of the motor and reducing the size, it is necessary to increase the space factor of the coil. In order to increase the space factor, a plurality of segment coils in which a wire material having a large cross-sectional area is formed in a required shape in advance are mounted in the core slot, and the connection end of the coil end portion extending from the slot is welded. Thus, it is possible to adopt a method of connecting and configuring the coil. In the segment coil, the coil cross-sectional area can be set large, so that a large current can flow, the space factor in the slot can be set large, and the output of the motor can be increased.

  On the other hand, since a large current flows through the segment coil, when segment coils belonging to different phases are arranged close to or in contact with each other at the coil end portion, the voltage between the coils increases and partial discharge tends to occur. In order to ensure insulation between coils where partial discharge is likely to occur without reducing the space factor, it is effective to provide a thick insulating coating on the outer peripheral surface where partial discharge is likely to occur at the coil end portion. . However, with the conventional method, it is very difficult to form an insulating coating having a large thickness in a partial region of the outer peripheral surface of the coil.

  The present invention solves the above-mentioned conventional problems, and can form a thick and uniform insulating coating with a small number of processes, and provide a uniform insulating coating at a required site where it is necessary to ensure insulation. It is an object of the present invention to provide a method for manufacturing a wire and a wire that can be used.

Invention of Claim 1 of this application is a manufacturing method of a wire provided with insulation coating , Comprising: In the predetermined area | region of the outer peripheral surface of the wire material provided with the basic insulation coating , polyimide resin, polyesterimide resin, or polyamideimide and the coating layer forming step of forming a coating adhesive layer was coated wearing predetermined thickness of the insulating resin material made of resin overlaid on the basic insulation coating, the surface hardened layer to cure the surface of the coating adhesive layer by plasma treatment It includes a forming step and a thermosetting step of curing the coating layer to the inside by heat treatment.

  In the present invention, in the surface hardened layer forming step, the surface of the coating layer formed by applying the insulating resin material to the wire material is cured by plasma treatment. Thereafter, by performing a heat treatment, the entire coating layer is cured to form an insulating coating.

  Since the thermosetting process is performed after the surface hardened layer is formed, the insulating resin material softened or melted in the initial stage of the thermosetting process can be prevented from flowing. For this reason, the whole coating layer can be hardened, maintaining the surface form after coating. This makes it possible to prevent the thickness of the coating layer from changing in the thermosetting process, and even when a thick coating layer is formed, a coating layer having a uniform thickness is formed. can do. In addition, a thick insulating coating can be formed by a single coating layer forming process and thermosetting process, and the manufacturing process and manufacturing cost can be greatly reduced.

  The type and form of the target wire are not particularly limited. It is possible to form not only a wire having a circular cross section but also an insulating coating of a wire having a rectangular cross section with a uniform thickness.

  The insulating coating according to the present invention can be formed on the entire outer peripheral surface of the wire, or can be formed in a part of the region. By adopting the present invention, the cured layer is formed so as to cover the surface of the coating layer, and the entire coating layer can be cured while maintaining the surface form. It is possible to form an insulating coating layer having a large thickness and a uniform thickness.

For example, as in the invention described in claim 2, the wire is a segment coil wire having a rectangular cross section, and the coating layer forming step includes a predetermined length range of a side surface including at least one side of the rectangular cross section. It can be performed by applying the insulating resin material.

  By adopting the above manufacturing method, it extends from the slot of the core and forms a thick insulation coating at the part where the segment coils having a large potential difference come into contact or close to each other. It becomes possible to prevent. In addition, the site | part which provides the said insulation coating can also be formed in the predetermined length range of the side surface containing one side of a rectangular cross section according to the segment coil arrange | positioned adjacently, or covers the perimeter of a rectangular cross section. The insulating coating can also be formed over a predetermined length.

The plasma treatment for performing the surface hardened layer step according to the present invention is not particularly limited as long as it can be cured by promoting the crosslinking reaction of at least the surface portion of the coating layer. For example, as in the invention described in claim 3 , the plasma treatment can be performed using low temperature plasma by glow discharge.

  Since the low temperature plasma treatment has a low operating temperature, it can be applied to a resin having low heat resistance and hardly softens, so that a required cured layer can be formed on the surface of the coating layer. In addition, since the surface of the coating layer that has been subjected to low-temperature plasma treatment has a structure in which organic thin films are highly crosslinked, it is also expected to increase the mechanical properties such as heat resistance and wear resistance of the insulating coating. it can.

  The low-temperature plasma treatment by glow discharge can be performed at a frequency of 1 to 13.56 MHz, a pressure of 10 to 100 Pa, an output of 10 to 100 W, a gas flow rate of 5 to 100 ml / min, and a time of 10 to 100 seconds. Furthermore, it is more preferable to carry out at a frequency of 10 to 13.56 MHz, a pressure of 30 to 50 Pa, an output of 40 to 60 W, a gas flow rate of 10 to 30 ml / min, and a time of 30 to 60 seconds.

  Various coils can be formed using the wire according to the present invention. Further, the coil can be applied not only to a motor stator but also to various stators such as a power generation stator.

  A wire having a large thickness and a uniform insulation coating can be manufactured at low cost.

It is a fragmentary perspective view which shows an example of the stator which mounted | wore with the coil formed from the wire which concerns on this invention. It is a front view of the principal part of the coil shown in FIG. It is sectional drawing which follows the III-III line in FIG. It is an expanded sectional view of the principal part of FIG. It is a figure which shows the difference with the thickness of each part of the insulating coating layer in the cross section of the coil shown in FIG. 2, and average thickness. It is a figure which shows the cross section of the coil which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows typically the characteristic of the coil cross section formed by the conventional method. It is a figure which shows the difference with the thickness of each part of insulation coating in the coil cross section formed by the conventional method, and average thickness, and is a figure equivalent to FIG.

  Embodiments of the present invention will be specifically described below with reference to the drawings. In the present embodiment, the present invention is applied to a wire having a rectangular cross section, and a segment coil is formed using this wire.

  FIG. 1 is a perspective view of a main part of a stator 2 configured by mounting a segment coil 1 according to the present invention on an annular core 3.

  The annular core 3 has a thick annular structure made of a magnetic material, and slots 4 that penetrate the inner peripheral portion in the axial direction and open to the inner peripheral surface are formed at predetermined intervals. FIG. 1 shows a state in which a part of the segment coil 1 is attached to a part of the slot 4 for easy understanding.

  The slot 4 is formed so as to substantially correspond to the width of the segment coil 1. For example, by accommodating the straight portion 1b of the segment coil 1 having the formation as shown in FIG. The segment coil 1 is attached to the core 3.

  The material which comprises the said core 3 is not specifically limited. For example, a core formed by compacting magnetic powder or a core formed by stacking magnetic steel plates can be employed.

  For example, in a three-phase induction motor, a plurality of segment coils each grouped into a U phase, a V phase, and a W phase are assembled in the slot 4 at a predetermined interval.

  As shown in FIG. 2, each segment coil 1 includes a pair of linear portions 1b accommodated in the slot 4, and a pair of coil end portions that extend from both axial ends of the slot 4 and have a mountain shape. 1a and 1c. One coil end portion 1c is provided with connection portions 5a and 5b for connecting to a segment coil of the same phase by removing the insulation coating. The coil end portions 1c of the segment coils arranged on the innermost and outermost sides in the radial direction of the stator are connected to the same-phase segment coils accommodated in different slots. A connecting portion that is bent in a pattern and connects to an adjacent segment coil is provided.

  The segment coil 1 according to the present embodiment is formed by bending a wire material 9 that is formed of a conductive metal such as copper and has a rectangular cross section into a required form. A basic insulating coating 10 is formed on the entire outer periphery excluding the connecting portions 5a and 5b. The basic insulating coating 10 is configured to ensure insulation between adjacent in-phase segment coils and the annular core 3 in the slot 4. The basic insulating coating 10 is made of a polyimide resin having a thickness of 5 μm to 25 μm. The basic insulating coating 10 is formed by a known conventional method, and is bent after the basic insulating coating 10 is formed.

  In the stator 2 of the said form, it is made to contact or adjoin with the coil which belongs to a different phase in coil end part 1a, 1c. For this reason, partial discharge tends to occur between the coils of these portions.

  In the present embodiment, the additional insulating coating 11 is formed in a region where partial discharge is likely to occur. As shown in FIG. 3, the additional insulating coating 11 is configured by providing an insulating coating made of an insulating resin having a large thickness so as to overlap the basic insulating coating 10.

  The additional insulating coating 11 is formed as follows.

  The base insulating coating 10 is formed, and a coating layer 11a coated with an insulating resin material is formed on a predetermined portion of the coil end portions 1a and 1c of the segment coil wire that is bent into a predetermined shape. In the segment coil 1 according to the present embodiment, a coating layer 11a having a thickness of 80 μm to 100 μm is formed over a predetermined length so as to overlap the basic insulating coating 10.

  Various thermosetting resins can be used as the insulating resin material. For example, the same polyimide resin as the basic insulating coating 10 can be used. Further, since the additional insulating coating 11 is not subjected to bending, an inexpensive insulating resin material having a low elongation at break can be employed. For example, in addition to the polyimide resin, a polyesterimide resin, a polyamideimide resin, a phenol resin, an epoxy resin, or the like can be used.

  In the present embodiment, a varnish adjusted to a viscosity or the like that can form the coating layer by dissolving the insulating resin material in a solvent is overcoated on the basic insulating coating to form the coating layer 11a. A deposition layer forming step is performed. The coating layer forming step can be performed by various methods. For example, the region where the additional insulating coating 11 is not formed can be masked with a tape material or the like, and the varnish can be applied to the surface region where masking is not performed.

  Next, the segment coil 1 provided with the coating layer 11a is subjected to plasma treatment. The plasma processing according to the present embodiment is performed using He gas or Ar gas using low temperature plasma obtained by glow discharge. For example, it can be carried out at a frequency of 13.56 MHz, a pressure of 40 Pa, an output of 50 W, a gas flow rate of 20 ml / min, and a time of 40 seconds.

In the present embodiment, as described above, the plasma processing is performed in the He or Ar gas environment, but the plasma processing can also be performed in the O ₂ gas or N ₂ gas environment. By performing plasma treatment in an O ₂ gas or N ₂ gas environment, it becomes possible to add hydrophilicity or adhesiveness to the surface. By making the surface hydrophilic or adhesive, for example, when the coil end portion is embedded in the resin material, the adhesiveness with the resin material or the like can be improved.

  When the coating layer 11a is subjected to plasma treatment, as shown in FIG. 4, at least the surface portion of the coating layer 11a is promoted to form a hardened surface layer 12a. Since the plasma treatment is performed at a low temperature, the coating layer 11a is not softened or melted, and the surface portion is cured while maintaining the surface form of the coating layer 11a. The thickness of the surface hardened layer 12a formed by the plasma treatment is not particularly limited, and is formed with a thickness that can maintain the surface form even when the inside of the coating layer is softened in the thermosetting step described below. It only has to be. For example, a hardened surface layer having a thickness of 50 μm to 150 μm can be provided.

  Next, a heat curing step is performed in which the segment coil 1 that has been subjected to the plasma treatment is heat-treated at a predetermined temperature to cure the interior of the coating layer 11a.

  In the thermosetting step, the heating temperature and the heating time are set according to the employed thermosetting resin material and the thickness of the coating layer 11a. In the present embodiment, the thermosetting process is performed by heating the entire segment coil at a temperature of 250 ° C. for 0.5 hours. By performing the thermosetting step, the internal hardened layer 12b is formed.

  In this embodiment, since the segment coil 1 is configured using a wire material that has been cut into a predetermined shape and bent in advance, the entire segment coil 1 can be put into a heating furnace and heated uniformly. it can. For this reason, the coating layer 11a can be hardened reliably.

  In this embodiment, since the thermosetting process is performed after the surface hardened layer 12a is formed, it is possible to prevent the insulating resin material softened or melted in the initial stage of the thermosetting process from flowing. For this reason, the whole coating layer 11a can be hardened, maintaining the surface form after coating layer formation. This makes it possible to prevent the thickness of the coating layer 11a from changing in the thermosetting process, and even when the thick coating layer 11a is formed, the additional insulating coating having a uniform thickness is formed. 11 can be formed. In addition, the additional insulating coating 11 having a large thickness can be formed by a single coating layer forming process and thermosetting process, and the manufacturing process and manufacturing cost can be greatly reduced.

  In addition, since the low temperature plasma treatment has a low operating temperature, it can be applied to a resin having low heat resistance and hardly softens, so that a required cured layer can be formed on the surface of the coating layer. it can. Moreover, the surface of the coating layer that has been subjected to the low-temperature plasma treatment is subjected to a heat treatment in addition to the plasma treatment, and thus has a structure in which the organic thin film is highly crosslinked. For this reason, a hardened surface layer having a large degree of polymerization, hardness, density, etc. is formed, and an effect that mechanical properties such as heat resistance and wear resistance of the surface of the additional insulating coating are enhanced can be expected.

  In FIG. 5, the difference of the thickness of each part with respect to the thickness of each part of the additional insulation coating 11 in the coil 1 formed by the said coil manufacturing method based on this invention and the average thickness of the additional insulation coating 11 is shown. In the embodiment shown in FIG. 5, the average thickness of the insulating coating is 0.096 mm, whereas the difference in the thicknesses of the corners (2), (6), (10), and (14) is −0.006 mm. (-6.2% with respect to the average thickness) to +0.005 mm (+ 5.2% with respect to the average thickness).

  FIG. 7 is a diagram schematically showing changes in the thickness of the additional insulating coating 211 in a coil formed by a conventional method. FIG. 8 shows the thickness of each part of the additional insulating coating 211 formed by the conventional method and the difference in thickness of each part with respect to the average thickness of the additional insulating coating 211, and corresponds to FIG. . In the conventional method, the average thickness of the additional insulating coating 211 is 0.089 mm, whereas the difference in the thicknesses of the corners (2) (6) (10) (14) is −0.016 mm ( -18% of the average thickness) to -0.012 mm (-13% of the average thickness). Therefore, the additional insulation coating 11 of the segment coil 1 formed by the manufacturing method according to the present invention has a very high uniformity compared to the thickness of the additional insulation coating 211 formed by the conventional method. For this reason, a highly reliable insulating coating can be formed by the manufacturing method according to the present invention.

  In the above-described embodiment, the additional insulating coating 11 is provided so as to overlap the entire circumference of the basic insulating coating 10 in the predetermined length range of the segment coil 1. However, the side surface including at least one side of the rectangular cross section is predetermined. The insulating coating layer can be formed in the length range. For example, as shown in FIG. 6, the additional insulating coating 111 can be formed only on the side surface including one side of a rectangular cross section. Also in this case, since the surface hardening layer forming step by the plasma treatment is performed, the surface of the coating layer 111a formed from the insulating resin material can be cured, and then the thermosetting step can be performed. Similar to the embodiment, the additional insulating coating 111 having a uniform thickness can be formed.

  In the above-described embodiment, the additional insulating coating 11 is provided on the basic insulating coating 10. However, a thick insulating coating layer is directly formed on the wire material not provided with the basic insulating coating 10. You can also.

  Furthermore, in the present embodiment, the present invention is applied to a segment coil formed from a wire having a rectangular cross section, but the cross-sectional form and coil form of the wire are not particularly limited. For example, a continuous circular cross-section is used. The insulating coating according to the present invention can be formed on a coil formed of a wire rod provided. Moreover, this invention is applicable not only to the wire material for coils but to the insulation coating wire material used for various uses.

  The scope of the present invention is not limited to the embodiment described above. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  A thick insulating film having a uniform thickness can be formed with a small number of steps, and a uniform insulating film having a uniform thickness can be provided at a required portion where it is necessary to ensure insulation.

1 Segment coil (wire material)
2 Stator 9 Wire material 11a Coating layer 12a Surface hardened layer 12b Internal hardened layer

Claims (3)

A method of manufacturing a wire with an insulating coating,
Application in which an insulating resin material made of polyimide resin, polyesterimide resin, or polyamideimide resin is applied to a predetermined area on the outer peripheral surface of a wire material provided with a basic insulating coating so as to overlap with the basic insulating coating and to have a predetermined thickness. A coating layer forming step of providing a layer;
A surface hardened layer forming step of hardening the surface of the coating layer by plasma treatment;
And a thermosetting step of curing the coating layer to the inside by heat treatment. The wire is a segment coil wire having a rectangular cross section,
The said coating layer formation process is a manufacturing method of the wire of Claim 1 performed by apply | coating the said insulating resin material to the predetermined length range of the side surface containing at least 1 side of the said rectangular cross section.   The wire manufacturing method according to claim 1, wherein the plasma treatment is performed using low-temperature plasma by glow discharge.

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