JP5821410B2 - Insulated wire manufacturing method - Google Patents

Description

  The technical field of the present invention relates to a technique for manufacturing an insulated wire covered with an insulating layer formed by coating an insulating resin. Specifically, the present invention relates to a method for coating an electric wire surface that coats a high-viscosity resin varnish on the surface of the electric wire, a method for producing an insulated wire including a step of coating an insulating resin varnish on the surface of the electric wire, and a method for producing the same According to the insulated wire manufactured by

  An insulated wire covered with an insulating layer formed by coating an insulating resin on the surface of an electric wire such as a copper wire is used for a coil wire constituting a motor or a generator. This insulated electric wire is produced by dissolving an insulating resin in a solvent to produce an insulating varnish, coating the insulating varnish on the outer periphery of the electric wire, and then heating to cure the insulating varnish.

  The insulating varnish varies depending on the wire diameter and resin, but a thick wire having a diameter of 0.5 mm or more usually has a high viscosity of about 2 to 10 Pa · s. Therefore, conventionally, the method of coating the surface of an electric wire such as a copper wire with an insulating varnish has been limited to immersing the electric wire in the insulating varnish or directly applying the insulating varnish to the electric wire with a brush or the like. Among them, many methods have been adopted in which an electric wire is continuously passed through a tank filled with an insulating varnish and then heated to cure the insulating varnish. FIG. 3 is a diagram schematically showing the painting and heating steps.

  In FIG. 3, the white arrow represents the direction of movement of the electric wire (copper wire or the like). As shown in the figure, the electric wire is first passed through a tank filled with insulating varnish, the insulating varnish is attached to the surface of the electric wire, and then heated to cure the insulating varnish. When the insulating varnish layer is thick, problems such as foaming occur due to evaporation of the solvent during heating. Therefore, usually, the amount of the insulating varnish attached in one step is reduced, and this step is repeated multiple times. Is adopted.

Japanese Patent No. 2838690

  In recent years, a manufacturing method using a U-shaped conductor (segment coil) has been adopted in a vehicle generator and motor. In this manufacturing method, the insulated wire that constitutes the coil is divided into a plurality of segment coils, these are aligned and combined, then inserted into the slot, and the segment coils are joined together to produce a coil (particularly a stator coil). Is done. According to this method, compared to the conventional method of forming a coil by winding a continuous wire having a circular cross section (round line), the space factor of the slot can be improved, and the manual processing of the terminal processing is omitted. Advantages such as enabling automatic assembly can be obtained.

  As the insulated wire forming this segment coil, a rectangular wire having a flat rectangular cross section is used, but the required thickness of the insulating layer differs depending on the portion in the segment coil. For example, a thick insulating layer is required at a portion in contact with an adjacent segment coil or core between motor phases, but there are portions where the insulating layer may be thin and unnecessary portions at other portions.

  Therefore, in order to reduce the amount of insulating varnish used, it is desired to manufacture an electric wire having an insulating layer only at a predetermined portion or an electric wire having a different insulating layer thickness depending on the portion. There has been a demand for a method of coating an insulating varnish that can freely change the coating amount. However, in the conventional method of continuously passing an electric wire through a tank filled with an insulating varnish, it is difficult to paint only a predetermined portion of the electric wire or to freely change the thickness of the coating depending on the portion of the electric wire.

  This invention makes it a subject to provide the insulated wire which has the insulating layer formed by the coating method of the resin varnish which can change the coating amount of the resin varnish freely by the site | part of an electric wire, and this coating method.

  Conventionally, even if the insulating varnish is uniformly coated on the surface of the electric wire, the varnish becomes highly uneven due to surface tension etc. due to the high viscosity. It was difficult to form at a desired site. In addition to the above-described problems, the present invention also solves the problems of the prior art and provides a method for manufacturing an insulated wire having an insulating layer having a uniform thickness at a desired site.

  As a result of diligent study, the present inventor has made it possible to freely change the coating amount of the insulating varnish depending on the part of the electric wire, if the insulating varnish is applied to the surface of the electric wire by spray coating using a high-viscosity material spraying device. Then, after coating the insulating varnish on the surface of the electric wire, it was found that an insulating layer having a uniform thickness can be formed by heating the insulating varnish at a relatively low temperature for a short time, thereby completing the present invention.

The present invention is a method for coating an electric wire, characterized in that a resin varnish is sprayed on the surface of the electric wire by a high viscosity material spraying device. According to this coating method, the insulating varnish can be painted only at a desired portion of the electric wire. Also, the coating thickness of the insulating varnish can be freely changed depending on the part of the electric wire.

  The resin varnish is a high-viscosity liquid of 10 Pa · s or more obtained by dissolving a resin in a solvent. In particular, an insulating varnish obtained by dissolving an insulating resin forming an insulating layer of an insulated wire in a solvent can be given as a representative example.

  The high-viscosity material spraying device is a spraying device that can atomize and discharge a high-viscosity liquid of about 5 to 10 Pa · s. For example, a high-viscosity material spraying device described in Japanese Patent No. 2838690 can be used in the present invention. This high-viscosity material spraying device has a pressure feed pump that supplies high-viscosity material and an air control device that supplies compressed air, and atomizes the high-viscosity material by mixing the high-viscosity material and compressed air with the nozzle part. A high-viscosity material spraying device, in which a nozzle tube is formed concentrically with an outer nozzle for air ejection and an inner nozzle for high-viscosity material ejection as a spraying port, and the nozzle opening for high-viscosity material ejection is used for air ejection A high-viscosity material spraying device that protrudes compared to a nozzle tip opening.

  The spraying of the resin varnish is provided with a discharge port of a high-viscosity material spraying device so as to face the surface of the electric wire, and while moving the electric wire in one direction, a predetermined portion of the electric wire, that is, a portion where application of the resin varnish is desired When the oil reaches the position facing the discharge port, the high-viscosity material spraying device is operated to spray the resin varnish and paint (spray coating). By this method, a high-viscosity resin varnish is applied only to a predetermined portion in the length direction of the electric wire, and an electric wire having a portion coated with the resin varnish and a portion not coated in the length direction can be produced. Also, by changing the spray amount of the resin varnish of the high-viscosity material spraying device, the coating amount can be freely changed depending on the part in the length direction of the electric wire, and it can be changed to the desired part in the length direction of the electric wire. Insulated electric wires having insulating layers with different thicknesses can be produced.

  When coating the resin varnish only on the surface in one direction of the cross section of the electric wire, one high-viscosity material spraying device is provided so that the discharge port faces the surface in the direction in which the coating is desired. However, in the normal case of manufacturing an insulated wire or the like, it is desired to coat the resin varnish in all directions of the cross section of the wire. In such a case, it is required to install a plurality of high-viscosity material spraying devices so that the discharge port faces the surface in each direction of the cross section of the electric wire. When two high-viscosity material spraying devices are provided, it is preferable to provide the two high-viscosity material spraying devices so as to be in the position of the line target with the electric wire as the target axis.

  By installing multiple high-viscosity material spraying devices so that the discharge ports face the surface in each direction of the cross section of the wire, and adjusting the spray amount of each device, the thickness of the insulating layer is Different insulated wires can be produced in each direction. For example, in the production of the segment coil, a thick insulating layer may be formed on the surface side in contact with the adjacent segment coil or core, and a thin insulating layer may be formed on the other surface side to save insulating varnish. it can.

The present invention has a coating process for spraying and coating an insulating varnish on an electric wire by a high-viscosity material spraying device, and a curing process for curing the coated insulating varnish. It is.

This invention is a method for producing an insulated wire, characterized in that the coating of the insulating varnish on the surface of the wire is carried out by the above-described wire coating method. The insulating varnish is coated and then cured on the surface of the electric wire, an insulating layer covering the surface of the electric wire is formed, and an insulating electric wire having an insulating layer having a predetermined thickness at a predetermined portion is manufactured.

  The insulating varnish can be cured industrially in a short time by heating the electric wire to the boiling point or higher of the solvent constituting the insulating varnish. By this heating, the solvent is dried and removed from the insulating varnish applied on the surface of the electric wire, and an insulating layer made of a cured resin film is formed. Heating can be performed by a method similar to the method performed when the insulating varnish is cured by a conventional method of manufacturing an insulated wire. Moreover, you may heat in a thermostat by batch processing.

The present invention is characterized in that the electric wire is a segment coil.

  The present invention is particularly suitably applied to the production of U-shaped conductors (segment coils) that have been used in recent years for the formation of coils for vehicle generators, motors and the like. The segment coil is manufactured by cutting a rectangular wire at a predetermined length and bending it into a U shape. Among the flat wire surfaces (side surfaces), a surface in contact with an adjacent segment coil and a surface in contact with a core; The required thickness of the insulating layer is different from other surfaces. In addition, when a segment coil is manufactured from a rectangular wire, if the insulating layer at a portion to be bent with a small curvature is thick, the insulating layer is easily broken. Therefore, it is preferable that the insulating layer at the portion is thin. According to the manufacturing method of the present invention, since the thickness of the insulating layer at a desired portion can be freely adjusted, it is possible to easily manufacture segment coils in which the desired thickness of the insulating layer varies depending on the portion.

The present invention includes a coating process for coating an insulating varnish on the surface of a wire, a curing process for curing the coated insulating varnish, and a viscosity of the insulating varnish at a viscosity of 25 ° C. after the coating process and before the curing process. It is a manufacturing method of the insulated wire characterized by having the film thickness smoothing process heated to the temperature which becomes 0.1-0.7 times for 5 second or more and 10 minutes or less.

As described above, even if the insulating varnish can be uniformly coated on the surface of the electric wire, the coating thickness (film thickness) of the insulating varnish varies depending on the surface tension and the like because the varnish has a high viscosity. The present inventors have conducted various experiments paint varnish, results of the examination of varnish film thickness distribution after coating, the film thickness is moving varnish problem tends to become uneven change immediately after coating occurs I found it.

  FIG. 2 is a cross-sectional view schematically showing the variation in the thickness of varnish application, but immediately after coating, even when the thickness is uniform as shown in FIG. As shown in FIGS. 2B and 2C, the thickness is not uniform. Therefore, it is difficult to obtain a desired thickness over the entire desired range. As a result, the thickness of the insulating layer after curing becomes non-uniform, and it is difficult to form an insulating layer having a uniform thickness in a desired range.

However, by heating for a relatively short time to a temperature relatively lower than the heating conditions in the curing process before the curing process, the influence of surface tension applied to the insulating varnish is alleviated and dispersed, resulting in uneven thickness The state can be corrected and an insulating layer having a uniform film thickness can be formed in a desired range. As a result, the insulation performance and quality of the insulated wire can be improved. That is, the present invention is characterized by providing a film thickness smoothing step by heating at a low temperature for a short time before the curing step in order to prevent varnish coating and non-uniform coating thickness occurring thereafter. It is a manufacturing method of an insulated wire.

  The heating temperature for preventing uneven thickness is a temperature at which the viscosity of the insulating varnish is 0.1 to 0.7 times the viscosity at 25 ° C. That is, the viscosity of the insulating varnish decreases as the temperature rises within a certain temperature range, but the heating temperature is equal to or higher than a temperature at which the viscosity at 25 ° C. is 0.7 times or less. By making the viscosity of the insulating varnish not more than 0.7 times the viscosity at 25 ° C., it is possible to sufficiently correct / prevent uneven thickness. On the other hand, by making the viscosity at least 0.1 times the viscosity at 25 ° C, it is possible to prevent dripping from the rectangular wire due to the low viscosity of the insulating varnish and maintain a good coating state, and prevent uneven thickness. Or even if the thickness becomes uneven. Therefore, it is desirable not to heat to a temperature at which the viscosity is lower than 0.1 times the viscosity at 25 ° C. Further, the insulating varnish is hard to be cured by not heating to a temperature at which the viscosity is lower than 0.1 times the viscosity at 25 ° C.

  The heating time for preventing uneven thickness is 5 seconds or more and 10 minutes or less, preferably 10 seconds or more and 5 minutes or less. By setting the heating time to 5 seconds or more, preferably 10 seconds or more, thickness nonuniformity can be corrected or nonuniformity can be prevented. On the other hand, by setting the heating time to 10 minutes or less, preferably 5 minutes or less, an increase in viscosity due to curing of the insulating varnish can be suppressed, thickness nonuniformity can be corrected, and nonuniformity can be prevented.

The curing step can be performed in the same manner as the curing of the insulating varnish in the present invention . That is, it can be performed by heating the electric wire to the boiling point or higher of the solvent constituting the insulating varnish, and the heating is the same as the method performed at the time of curing the insulating varnish in the conventional method for manufacturing an insulating electric wire. This can be done by various methods.

  According to the electric wire coating method of the present invention, the insulating varnish can be applied only to a desired portion of the electric wire. Also, the coating thickness of the insulating varnish can be freely changed depending on the part of the electric wire. Moreover, according to the method for manufacturing an insulated wire of the present invention using this coating method, an insulated wire having an insulating layer having a desired thickness at a desired site can be easily manufactured.

  According to the method for manufacturing an insulated wire of the present invention having a film thickness smoothing step, an insulated wire having an insulating layer with a uniform film thickness in a desired range is prevented, preventing unevenness of the film thickness after coating of the insulating varnish. It can be manufactured easily. Such a method for producing an insulated wire according to the present invention can be suitably applied to the production of a segment coil.

It is a schematic diagram which shows the manufacturing process of an example of the insulated wire of this invention. It is a schematic cross section which shows a mode when the insulation varnish is painted on the flat wire. It is a schematic diagram which shows the manufacturing process of the conventional insulated wire. It is a schematic cross section which shows an example of the insulated wire of this invention.

  Next, the form for implementing this invention is demonstrated concretely based on figures. Note that the present invention is not limited to this form, and can be changed to other forms as long as the gist of the present invention is not impaired.

FIG. 1 is a schematic diagram showing a process of forming an insulating layer at a desired site on the surface of the electric wire by the method for manufacturing an insulated electric wire of the present invention. This process corresponds to a method for manufacturing the above-described insulated wire, in which the coating process is performed by the above-described method for coating an electric wire.

  1 in the figure represents an electric wire, and the electric wire 1 has moved in the direction indicated by the white arrow in the figure. 2 in the figure represents a high-viscosity material spraying device for atomizing and discharging a high-viscosity insulating varnish. In this example, two high-viscosity material spraying devices 2 are positioned on the line object with the electric wire 1 as an axis. Is provided.

  The electric wire to which the present invention is applied is usually a copper wire, but is not limited thereto. The present invention can also be applied to the case where an insulating layer is formed on an aluminum wire, a silver wire, a copper wire plated with another metal, or the like. The cross-sectional shape of the electric wire is not particularly limited, and the present invention can be applied to a round wire having a circular cross section. However, the present invention is particularly preferably applied to a rectangular wire having a rectangular cross section.

Each discharge port 2 a of the high-viscosity material spraying device 2 faces the electric wire 1. And when the site | part which desires formation of the insulating layer of the electric wire 1 passes between the high-viscosity material spraying apparatuses 2, the spray 5a of insulating varnish is discharged in the sprayed state on the surface of the electric wire 1 from each discharge port 2a. (Spray coating) is performed, and an insulating varnish coating film 5 b is formed on the surface of the electric wire 1. That is, when the electric wire 1 passes between the two high-viscosity material spraying apparatuses 2, the coating process in the present invention is performed.

  As an insulating varnish, the thing similar to the insulating varnish used for manufacture of the conventional insulated wire can be used. For example, a varnish containing polyimide or polyamideimide, or a resin containing an inorganic filler such as alumina or silica can be used.

  When a portion of the electric wire 1 where the insulating layer is not formed passes between the high viscosity material spraying apparatuses 2, the insulating varnish is not discharged (spray coating). As a result, a portion where the insulating varnish is not coated is generated on the surface of the electric wire 1. 1a in FIG. 1 represents a portion where the insulating varnish is not coated.

  Moreover, the thickness of the coating film 5b of the insulating varnish can be changed by changing the discharge amount of the insulating varnish from the high viscosity material spraying apparatus 2. Thus, the insulating layer of different thickness can be formed by the site | part of the electric wire 1, or the site | part in which an insulating layer is not formed can be obtained. Furthermore, by adjusting the discharge amounts of the two high-viscosity material spraying apparatuses 2 to be different from each other, it is possible to produce insulated wires in which the thickness of the insulating layer is different in the cross-sectional direction of the wire 1.

  1 in FIG. 1 represents a heating device for smoothing the film thickness. The electric wire 1 that has passed between the high-viscosity material spraying apparatuses 2 and has the insulating varnish coating film 5b formed thereon is heated by the film thickness-smoothing heating apparatus 3 to perform a film thickness smoothing step. Even if the coating film 5b having a non-uniform thickness is formed in the above-described coating process, or even after the coating film 5b having a uniform thickness is formed, the insulating varnish is moved by surface tension or the like to have a non-uniform thickness, The film thickness is made uniform (smoothed) in the range heated by the heating device 3 for smoothing the film thickness. For example, even if the coating film 5b is in a state represented by (b) or (c) in FIG. 2, the film thickness smoothing step makes the uniformization represented by (a) in FIG. Smoothed film thickness.

  This heating may be performed only in a predetermined portion of the insulating varnish coating film 5 b or only in a predetermined direction of the cross section of the electric wire 1. This heating is performed at a temperature at which the viscosity of the insulating varnish is 0.1 to 0.7 times that at 25 ° C. (in the case of a normal insulating varnish, about 40 to 150 ° C.) for 5 seconds to 10 minutes. Is called. This condition is a temperature much lower than a heating condition in the curing step described later and for a short time.

  1 in FIG. 1 represents a heating device for varnish curing. The electric wire 1 in which the thickness of the coating film 5b is made uniform by the film thickness smoothing process is heated by the varnish curing heating device 4, and the curing process is performed. This heating condition is sufficient to dry and remove the solvent and cure the varnish, and is usually performed at 300 ° C. or higher for 1 minute or longer. That is, the temperature is much higher than the heating temperature in the film thickness smoothing step, and heating is performed for a long time. 5c represents an insulating layer formed by curing the insulating varnish.

FIG. 4 is a schematic cross-sectional view showing an example of the insulated wire of the present invention. This insulated wire is an example of the present invention . That is, in the figure, 6 is an electric wire, and 7 is an insulating layer covering the electric wire 6, but as is apparent from the figure, the electric wire 6 is a flat wire, and the inside of its side surfaces a1, a2, a3 and a4 Thus, the thickness of only the portion covering the side surface a1 of the insulating layer 7 is smooth, and the thickness of the portion covering the side surfaces a2, a3 and a4 is not smooth.

DESCRIPTION OF SYMBOLS 1 Electric wire 1a Area | part which the insulating varnish is not coated 2 High viscosity material spraying apparatus 2a Discharge port 3 Heating apparatus for film thickness smoothing 4 Heating apparatus for varnish hardening 5a Spray of insulating varnish 5b Coating film 5c of insulating varnish Insulating layer 6 Electric wire 7 Insulation layer

Claims (2)

A method for producing an insulated wire, comprising: a coating step of spraying and coating an insulating varnish on an electric wire by a high viscosity material spraying device; and a curing step of curing the coated insulating varnish,
The electric wire is a flat wire, and has an insulating layer on one side surface. In the formation of the insulating layer, the insulating varnish is formed at a viscosity of 0.1 at 25 ° C. after the coating step and before the curing step. It has a film thickness smoothing step of heating at a temperature that is up to 0.7 times for 5 seconds to 10 minutes,
The insulating layer is formed so that the insulating layer covers only a part of the surface of the electric wire, and the thickness of the insulating layer is smooth only on one side of the rectangular wire,
The electric wire is a segment coil, and the segment coil is manufactured by bending the flat wire into a U-shape,
The method for manufacturing an insulated wire, wherein a thickness of the insulating layer at a portion where the flat wire is bent is thinner than a thickness of the insulating layer other than the portion where the flat wire is bent.   The method for manufacturing an insulated wire according to claim 1, wherein the high-viscosity material spraying device is provided at a line-symmetric position with the wire as an axis.

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