JP2024076451A - Enameled wire manufacturing apparatus and method - Google Patents

Abstract

[Problem] To provide an apparatus and method for manufacturing an enameled wire with excellent productivity, capable of suppressing high-temperature oxidation corrosion even when a baking furnace is heated to a high temperature. [Solution] The apparatus for manufacturing an enameled wire (1) comprises an application device (7) for applying an enamel coating to the surface of a conductor (11a), and a baking furnace (8) for heating the conductor (11a) coated with the enamel coating and baking the enamel coating onto the conductor (11a) to form an insulating layer, and the baking furnace (8) has a high-temperature oxidation corrosion suppression layer made of cerium oxide on its inner surface. [Selected Figure] Figure 1

Description

The present invention relates to an apparatus and method for manufacturing enameled wire.

A known example of an enameled wire manufacturing device is one that includes an applicator that applies enamel paint to the surface of a conductor, and a baking furnace that heats the conductor with the enamel paint applied to it and bakes the enamel paint onto the conductor to form an insulating layer (see, for example, Patent Document 1).

Conventionally, high-temperature oxidation corrosion has been suppressed in baking furnaces by using materials with high heat resistance for the materials that make up the baking furnace. More specifically, for example, by constructing the baking furnace from SUS309, a heat-resistant stainless steel, high-temperature oxidation corrosion can be suppressed, and the life of the baking furnace can be extended.

Japanese Patent Publication No. 61-18287

The inventors considered increasing the temperature of the baking furnace in order to increase the manufacturing speed of enameled wire and improve productivity. However, in the baking furnaces that have been used in the past, when the temperature is raised to a high temperature, for example 750°C, high-temperature oxidation corrosion occurs, in which the inner surface of the baking furnace is oxidized and corroded. As high-temperature oxidation corrosion of the inner surface of the baking furnace progresses, the oxide film formed on the inner surface of the baking furnace grows and peels off from the inner surface of the baking furnace and adheres to the enameled wire. The oxide film that adheres to the enameled wire can cause foreign matter, and there are concerns that it may cause problems such as a poor appearance of the enameled wire and a decrease in its electrical and mechanical properties. There is also a concern that the inside of the baking furnace may be damaged due to high-temperature oxidation corrosion, so measures are desired.

The present invention aims to provide an apparatus and method for manufacturing enameled wire that can suppress high-temperature oxidation corrosion even when the baking furnace is heated to a high temperature, and has excellent productivity.

The present invention aims to solve the above problems by providing an enameled wire manufacturing device that includes an applicator that applies enamel paint to the surface of a conductor, and a baking furnace that heats the conductor to which the enamel paint has been applied and bakes the enamel paint onto the conductor to form an insulating layer, the baking furnace having a high-temperature oxidation corrosion inhibition layer made of cerium oxide on its inner surface.

The present invention provides an apparatus and method for manufacturing enameled wire that can suppress high-temperature oxidation corrosion even when the baking furnace is heated to a high temperature, and has excellent productivity.

1A is a schematic diagram of an enameled wire manufacturing apparatus according to an embodiment of the present invention, and FIG. 1B is a schematic diagram of a baking furnace. FIG. 2 is a flow diagram showing a procedure for forming a high-temperature oxidation corrosion inhibiting layer. 1A is a photograph showing the observation results after the high-temperature cycle test of an example, and FIG. 1B is a photograph showing the observation results after the high-temperature cycle test of a comparative example.

[Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 1(a) is a schematic diagram of an enameled wire manufacturing apparatus 1 according to this embodiment. As shown in Figure 1(a), the enameled wire manufacturing apparatus 1 includes a conductor supplying machine 5 that supplies a conductor 11a, an annealing furnace 6 that anneals the conductor 11a, an applicator 7 that applies an enamel coating to the surface of the conductor 11a, a baking furnace 8 that heats the conductor 11a coated with the enamel coating and bakes the enamel coating onto the conductor 11a to form an insulating layer, and a winder 9 that winds up the enameled wire 11 obtained in the baking furnace 8.

The annealing furnace 6 is for annealing the conductor 11a before applying the enamel paint. In this embodiment, the annealing furnace 6 is provided near and below the baking furnace 8, so that the baking furnace 8 is heated from the outside by the heat generated in the annealing furnace 6. This configuration makes it difficult for the baking furnace 8 to cool, so that stable heating can be performed in the baking furnace 8 even if the running speed is increased, which contributes to improving the manufacturing speed and forming a uniform insulation layer. In addition, stable heating in the baking furnace 8 makes it possible to reduce the length and height of the baking furnace 8 and make the entire manufacturing device for the enamel wire 11 compact. In addition, this configuration allows the length of the annealing furnace 6 to be relatively long (can be made to be about the same length as the annealing furnace 6), so that the conductor 11a can be sufficiently annealed even if the running speed is increased.

The application of enamel paint by the applicator 7 and the baking of the enamel paint by the baking furnace 8 are repeated multiple times. Specifically, the conductor 11a that has passed through the baking furnace 8 is redirected by a pulley and returned to the applicator 7 multiple times. This forms an insulating layer of a specified thickness, and the enameled wire 11 is obtained. The enameled wire 11 is wound on the winder 9.

(Baking oven 8)
Fig. 1(b) is a schematic diagram of the baking furnace 8. As shown in Fig. 1(b), in this embodiment, a horizontal baking furnace 8 is used. The horizontal baking furnace 8 is structured to circulate hot air by a blower 83, so that it is easy to form a uniform high-temperature oxidation corrosion inhibitor layer on the inner surface of the baking furnace 8 by a method described later. However, the present invention is not limited to this, and can also be applied to a vertical baking furnace.

The baking oven 8 has a heating section 81 having a heater (not shown) for heating the air inside with the heater, a running line section 82 through which the conductor 11a coated with enamel paint is inserted, and a blower 83 for blowing the air heated by the heating section 81 (referred to as heated air) to the running line section 82. The blower 83 has an outlet 83a provided at one end of the heating section 81 and an intake 83b connected to the vicinity of the conductor inlet 82a of the running line section 82. At the end of the heating section 81 opposite the blower 83, a turn section 81a is provided that is curved in an approximately U-shape so that the air flow path is bent 180 degrees, and the outlet (heated air outlet) of the turn section 81a is connected to the vicinity of the conductor outlet 82b of the running line section 82. The heated air supplied from the heating section 81 through the turning section 81a to the running section 82 flows from the conductor outlet 82b side to the conductor inlet 82a side in the opposite direction to the running direction of the conductor 11a, and the enamel paint is baked by heating with the heated air. Then, part of the heated air is sucked into the intake port 83b and returns to the heating section 81, and the remainder is discharged from the conductor inlet 82a. In FIG. 1(b), the air flow in the baking furnace 8 is represented by an outlined arrow, and the running direction of the conductor 11a is represented by a filled arrow.

The heating section 81 and the running section 82 are provided with multiple sockets 84 for attaching thermocouples for measuring temperature. In the illustrated example, four sockets 84 are formed on the heating section 81 and three sockets 84 are formed on the running section 82.

The heating section 81 and the running section 82 are preferably made of a material that is resistant to high-temperature oxidation corrosion, such as heat-resistant stainless steel SUS309. However, stainless steel has the characteristic that the initial oxide film is the most resistant to high-temperature oxidation corrosion, and once this oxide film peels off, the growth and peeling of the oxide film progresses at an accelerated rate. Therefore, some kind of countermeasure is required for use at high temperatures, such as 750°C.

Therefore, in the enameled wire manufacturing apparatus 1 according to the present embodiment, a high-temperature oxidation corrosion suppression layer (not shown) made of cerium oxide is provided on the inner surface of the baking furnace 8. By providing a high-temperature oxidation corrosion suppression layer made of cerium oxide on the inner surface of the baking furnace 8, high-temperature oxidation corrosion is unlikely to occur on the inner surface of the baking furnace 8 even if the temperature of the baking furnace 8 is set higher than before (for example, about 750°C). As a result, it is possible to increase the running speed of the conductor 11a (the conductor 11a coated with enamel paint) running on the running line portion 82 of the baking furnace 8 by setting the temperature of the baking furnace 8 higher than before (for example, about 750°C), and it is possible to improve the manufacturing speed of the enameled wire 11. Furthermore, since a high-temperature oxidation corrosion suppression layer made of cerium oxide is formed on the inner surface of the baking furnace 8, an oxide film caused by high-temperature oxidation corrosion is unlikely to occur on the inner surface of the baking furnace 8, and a defect such as an oxide film peeled off from the inner surface of the baking furnace 8 adhering to the enameled wire 11 as a foreign matter is unlikely to occur. As a result, product defects caused by foreign matter consisting of oxide coatings (i.e., poor appearance of the enameled wire 11 and deterioration of electrical and mechanical properties) can also be reduced.

In the baking furnace 8, the heating section 81 where the heater is provided is the hottest, so it is desirable that the high-temperature oxidation corrosion inhibition layer is formed so as to cover at least the inner surface of the heating section 81. More desirably, the high-temperature oxidation corrosion inhibition layer is formed so as to cover the entire inner surface of the heating section 81 and the running line section 82. In this embodiment, the high-temperature oxidation corrosion inhibition layer is formed so as to cover the entire inner surface of the baking furnace 8. The thickness of the high-temperature oxidation corrosion inhibition layer is desirably 0.2 μm or more. This makes it possible to obtain sufficient resistance to high-temperature oxidation corrosion.

(Method of manufacturing enameled wire)
The method for producing an enameled wire according to this embodiment is a method for producing an enameled wire 11 by using the enameled wire production apparatus 1 described in Figures 1(a) and 1(b). That is, the method for producing an enameled wire according to this embodiment includes a step of applying an enamel coating to the surface of a conductor 11a by using an application device 7, and a step of heating the conductor 11a coated with the enamel coating by using a baking furnace 8 having a high-temperature oxidation corrosion inhibition layer made of cerium oxide on its inner surface, thereby baking the enamel coating onto the conductor 11a to form an insulating layer. As a result, the temperature of the baking furnace 8 can be set to a higher temperature (e.g., about 750°C) than in the past, thereby improving the production speed of the enameled wire 11, and providing an enameled wire 11 with excellent productivity.

(Formation of high-temperature oxidation corrosion inhibition layer)
2 is a flow diagram showing the procedure for forming the high-temperature oxidation corrosion suppression layer. As shown in FIG. 2, first, in step S1, the openings (conductor inlet 82a and conductor outlet 82b) of the baking furnace 8 are blocked. Here, the conductor inlet 82a and the conductor outlet 82b are blocked by sealing with vinyl tape. Then, in step S2, a mixture of cerium oxide and ethanol is prepared. Here, powdered cerium oxide and ethanol are mixed in a mass ratio of 1:9 to prepare the mixture. Note that the order of steps 1 and 2 may be reversed. That is, the openings of the baking furnace 8 may be blocked after the mixture of cerium oxide and ethanol is prepared.

Then, in step S3, the blower 83 is operated. Here, the blower 83 is driven so that air is circulated inside the baking furnace 8 at an air volume of 35 ^m3 /min. Then, in step S4, the mixed liquid is sprayed into the baking furnace 8 from the thermocouple sockets 84 by a sprayer. Since there are seven sockets 84 in this embodiment, the mixed liquid is sprayed for 30 seconds from each socket 84 in order from the upwind side (the side closer to the outlet 83a of the blower 83) to the downwind side in the air flow inside the furnace. This allows the mixed liquid to be evenly applied to the entire inner surface of the baking furnace 8.

After that, in step S5, the thermocouple sockets 84 are blocked and air is circulated inside the furnace. Here, air is circulated for about 30 minutes with all sockets 84 blocked. Then, in step S6, the inside of the baking furnace 8 is heated to fix a high-temperature oxidation corrosion inhibition layer on the inner surface of the baking furnace 8. Here, the temperature inside the furnace is raised to 300°C and held for 6 hours, thereby evaporating the ethanol and forming a high-temperature oxidation corrosion inhibition layer made of cerium oxide.

After that, in step S6, it is confirmed whether a high-temperature oxidation corrosion inhibition layer of sufficient thickness (0.2 μm or more) has been formed. The shape of the baking furnace 8 is complex, and there are some parts where the thickness of the high-temperature oxidation corrosion inhibition layer cannot be measured, but for such parts, it is advisable to carry out the treatment until it is possible to visually confirm that a white layer is present on the inner surface of the baking furnace 8. If the answer is YES in step S6, the treatment ends. If the answer is NO in step S6, the process returns to step S3 and the formation of the high-temperature oxidation corrosion inhibition layer continues.

By using a method of spraying the mixed liquid while circulating air inside the baking furnace 8, it is possible to apply the mixed liquid evenly to parts that are difficult to apply the liquid to manually or parts with complex shapes, such as the turn portion 81a, and it is possible to easily form a high-temperature oxidation corrosion inhibition layer on the inner surface of the baking furnace 8. It is also possible to form a high-temperature oxidation corrosion inhibition layer on an existing baking furnace 8, and it is possible to improve the resistance of the baking furnace 8 to high-temperature oxidation corrosion at low cost.

(Verification by high temperature cycle testing)
A rectangular test piece made of SUS316 and measuring approximately 10 mm x approximately 10 mm was used. A mixed liquid of cerium oxide and ethanol in a mass ratio of 1:9 was applied to the entire surface of the test piece, and the test piece was then dried to form a high-temperature oxidation corrosion inhibitor layer made of cerium oxide and having a thickness of 0.2 μm on the surface of the test piece, thereby producing the test piece for the example.

A test piece of the example and a test piece of the comparative example, which had the same configuration except that the high-temperature oxidation corrosion inhibition layer was not formed, were placed in a constant temperature bath at 750°C and left there for 25 minutes. After 25 minutes, the test piece was removed from the constant temperature bath and left at room temperature for 5 minutes, and a high-temperature cycle test was performed in which this cycle was repeated. The surface of the test piece after 513 cycles was observed. The observation results of the example are shown in Figure 3(a), and the observation results of the comparative example are shown in Figure 3(b).

As shown in FIG. 3(a), in the test piece of the embodiment in which the high-temperature oxidation corrosion inhibition layer was formed, no peeling of the oxide film occurred, and a Cr oxide film (the initial oxide film of SUS316) with excellent heat resistance remained on the surface of the test piece. In contrast, as shown in FIG. 3(b), in the test piece of the comparative example in which the high-temperature oxidation corrosion inhibition layer was not formed, it was confirmed that a large amount of peeling of the oxide film occurred. Note that the parts indicated by the arrows in FIG. 3(b) are the peeled parts. It was also confirmed that Fe-based oxides were generated in the peeled parts.

3(a) and (b) confirm that forming a high-temperature oxidation corrosion suppression layer made of cerium oxide makes it difficult for high-temperature oxidation corrosion to occur at high temperatures of about 750°C. From these results, it is believed that providing a high-temperature oxidation corrosion suppression layer made of cerium oxide on the inner surface of the baking furnace 8 makes it difficult for high-temperature oxidation corrosion to occur inside the baking furnace 8 even when enameled wire 11 is manufactured at high temperatures of about 750°C.

(Modification)
1(b) is merely an example, and the sockets 84 may be provided at equal intervals, for example. The number of sockets 84 is not limited to seven. However, the number of sockets 84 in the heating section 81 should preferably be equal to or greater than the number of sockets 84 in the running section 82. This is to allow the mixed liquid to be sufficiently sprayed in the heating section 81, which has a higher temperature, to form a high-temperature oxidation corrosion inhibition layer of sufficient thickness on the inner surface of the heating section 81.

In addition, in this embodiment, the mixed liquid is sprayed in sequence at each socket 84, but it may be sprayed simultaneously at multiple sockets 84. In addition, in this embodiment, it is assumed that a high-temperature oxidation corrosion inhibition layer is formed in an existing baking furnace 8, but the baking furnace 8 may be constructed by combining parts on which a high-temperature oxidation corrosion inhibition layer has already been formed.

(Functions and Effects of the Embodiments)
As described above, in the enameled wire manufacturing apparatus 1 according to this embodiment, the baking furnace 8 has a high-temperature oxidation corrosion suppression layer made of cerium oxide on its inner surface. This makes it possible to suppress high-temperature oxidation corrosion even when the baking furnace 8 is operated at a high temperature of, for example, 750° C., and thus makes it possible to extend the life of the baking furnace 8. Furthermore, by using the baking furnace 8 at a high temperature, it is possible to increase the manufacturing speed of the enameled wire 11 and improve productivity. Furthermore, it is possible to suppress the attachment of foreign matter generated by high-temperature oxidation corrosion to the enameled wire 11, thereby reducing product defects due to foreign matter and improving quality.

(Summary of the embodiment)
Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[1] An enameled wire manufacturing device (1) comprising an application device (7) for applying enamel paint to the surface of a conductor (11a), and a baking furnace (8) for heating the conductor (11a) to which the enamel paint has been applied and baking the enamel paint onto the conductor (11a) to form an insulating layer, the baking furnace (8) having a high-temperature oxidation corrosion inhibition layer made of cerium oxide on its inner surface.

[2] The baking furnace (8) has a heating section (81) having a heater for heating the air inside by the heater, a running section (82) through which the conductor (11a) coated with the enamel paint is inserted, and a blower (83) that blows the air heated by the heating section (81) to the running section (82), and the high-temperature oxidation corrosion inhibition layer is formed at least on the inner surface of the heating section (81). The enameled wire manufacturing apparatus (1) described in [1].

[3] The enameled wire manufacturing apparatus (1) described in [2], in which the high-temperature oxidation corrosion inhibition layer is formed on the entire inner surface of the heating section (81) and the running section (82).

[4] An enameled wire manufacturing device (1) according to any one of [1] to [3], further comprising an annealing furnace (6) for annealing the conductor (11a) before the enamel coating is applied, and configured to heat the baking furnace (8) from the outside using heat generated in the annealing furnace (6).

[5] An enameled wire manufacturing apparatus (1) according to any one of [1] to [4], in which the high-temperature oxidation corrosion inhibition layer has a thickness of 0.2 μm or more.

[6] A method for manufacturing an enameled wire, comprising the steps of: applying an enamel coating to the surface of a conductor (11a) using an application device (7); and heating the conductor (11a) coated with the enamel coating using a baking furnace (8) having a high-temperature oxidation corrosion inhibitor layer made of cerium oxide on its inner surface, thereby baking the enamel coating onto the conductor (11a) to form an insulating layer.

(Additional Note)
Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention.

1 ... enameled wire manufacturing apparatus 2 ... feeder 6 ... annealing furnace 7 ... coating device 8 ... baking furnace 11 ... enameled wire 11a ... conductor 81 ... heating section 82 ... wire running section 83 ... blower 84 ... socket

Claims (6)

an applicator for applying enamel paint to a surface of the conductor;
a baking furnace for heating the conductor to which the enamel paint has been applied and baking the enamel paint onto the conductor to form an insulating layer,
The baking furnace has a high-temperature oxidation corrosion inhibition layer made of cerium oxide on its inner surface.
Enamelled wire manufacturing equipment. The baking oven includes a heating unit having a heater for heating the air inside the oven, a running line portion through which the conductor coated with the enamel paint is inserted, and a blower for blowing the air heated by the heating unit to the running line portion.
The high-temperature oxidation corrosion suppression layer is formed at least on the inner surface of the heating part.
2. The apparatus for producing an enameled wire according to claim 1. The high-temperature oxidation corrosion inhibition layer is formed on the entire inner surface of the heating portion and the running line portion.
3. The apparatus for producing an enameled wire according to claim 2. an annealing furnace for annealing the conductor before applying the enamel coating;
The baking furnace is configured to be heated from the outside by heat generated in the annealing furnace.
2. The apparatus for producing an enameled wire according to claim 1. The thickness of the high-temperature oxidation corrosion inhibition layer is 0.2 μm or more.
2. The apparatus for producing an enameled wire according to claim 1. applying an enamel coating to a surface of the conductor using an application device;
a step of heating the conductor coated with the enamel paint using a baking furnace having a high-temperature oxidation corrosion inhibition layer made of cerium oxide on its inner surface, thereby baking the enamel paint onto the conductor to form an insulating layer;
Equipped with
Manufacturing method of enameled wire.

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