JPS6120966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a resin-baked electric wire, in which resin is applied to the surface of a core wire and then baked.

The conventional manufacturing method for resin-coated wires is to apply resin such as varnish to the surface of the core wire using an applicator, and then
This is led into a baking furnace and heated from the outer periphery to bake the resin onto the core wire. During this baking,
Since the core wire is a metal such as copper, it has very good thermal conductivity, so it instantly reaches the same temperature as the resin coating, but the resin coating on the surface has poor thermal conductivity, so the temperature increases gradually, and the rate of temperature increase is slow. slow. For this reason, a lot of time is spent on printing. As a result, there were disadvantages such as a longer furnace length, higher equipment costs, excessive energy consumption, and slow line speed.

In order to improve this, the core wire before entering the applicator is passed through a preheater to preheat it to a higher temperature than the resin in the applicator, and then the high temperature core wire is passed through the applicator one after another to apply resin to its surface. A method has been proposed in which the coated resin is then baked onto the core wire in a baking furnace.

According to such a method, there is an advantage that baking can be performed in a short time without requiring time for baking in a baking furnace, and that the linear speed can be increased.
Furthermore, since the difference in curing between the inside and outside of the resin coating film is small, there is an advantage that a high-quality resin baked wire can be manufactured.

However, in this method, the resin in the applicator is preheated to near its limit, and the heated core wire is placed on top of it, which has the disadvantage that the resin is likely to be heated and deteriorate. For this reason, there was a problem that the preheating temperature of the core wire could not be raised very much.

An object of the present invention is to provide a method for manufacturing a resin-baked electric wire that can be manufactured efficiently while preventing deterioration of the resin in the applicator.

Hereinafter, specific examples of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a core wire 1 is unwound from a supply stand 2, passes through a capstan 3 and an annealer 4, passes through a preheater 5, and enters an applicator 6. In particular, the preheater 5 heats the resin to a temperature higher than the temperature of the molten resin in the applicator 6. The core wire 1 heated to a high temperature by the preheater 5 is sequentially instantaneously coated with resin such as varnish by an applicator 6, and then enters the baking furnace 7. In the baking furnace 7, heating is performed using infrared rays, hot air, or the like. Since a preheater 5, an applicator 6, and a baking furnace 7 are arranged in parallel between the guide rollers 8 and 9, the core wire 1 is repeatedly subjected to preheating, resin coating, and baking to form the desired resin-baked electric wire 10. It passes through a turn sheave 11 and is wound up by a winding machine 12. The baking furnace 7 may be vertical or horizontal.

As shown in FIG. 2, the applicator 6 has a short distance between the sealing die 13 and the drawing die 14 to prevent heat exchange between the core wire 1 at a high temperature and the molten resin 15 at a lower temperature. In other words, the core wire temperature decreases due to the resin 15 and the core wire 1
This prevents the resin temperature from rising due to The applicator may be a conventional dobu-type applicator, but
Tank 16 containing resin 15 as in this embodiment
It is also possible to have a closed pressurized structure in which the tank 16 is closed and the pressure inside the tank 16 is increased.

Here, instant application means that while the core wire 1 heated by the preheater 5 to a temperature higher than the temperature of the molten resin 15 in the applicator 6 passes through the molten resin 15, heat conduction from the core wire 1 to the resin 15 is caused by the resin. 15 means that the coating is completed within a time that does not pose a substantial problem.

When the high-temperature core wire 1 stays in the resin 15 for a certain period of time or more, heat conduction from the core wire 1 to the resin 15 increases, the temperature of the resin 15 starts to rise rapidly, and the resin 1
This causes problems such as a decrease in the viscosity of the resin 15 and an increase in the rate of deterioration of the resin 15.

As shown in Fig. 3, when the time that a certain part of the core wire stays in the resin, that is, the coating time becomes longer than _t0 ,
The resin temperature begins to rise rapidly. This t ₀ changes depending on the core wire diameter, the type of resin, and the coating thickness. In the region t ₀ <t where the temperature of the resin increases, the core wire temperature immediately after the applicator becomes low. When the coating time becomes longer and the core wire temperature immediately after the applicator approaches the resin temperature, the effect of increasing the line speed disappears. For the effect of high-temperature preheating to be significant, the core wire temperature immediately after the applicator must be at least 10°C higher than the resin temperature. Note that the coating time t is L/v, where L is the distance between the sealing die and the drawing die, and v is the linear velocity.

Example A core wire of 1 mmφ was preheated to a core wire temperature of 250°C using a 5m baking furnace, the interval between the sealing die and the drawing die was set to 20mm, and varnish melted at 150°C was instantly applied. When a type of polyester enameled wire was manufactured, a wire speed of 60 m/min was obtained. This is about twice the linear speed of the conventional method. The characteristics of the obtained enameled wire were good. The varnish inside the applicator was heated by the core wire and the temperature rose, and the varnish did not deteriorate.

As explained above, in the present invention, the interval between the sealing die and the drawing die is narrowed within the applicator, and resin is sequentially and instantaneously applied to the high-temperature core wire.
Since the hot core wire contacts the resin within the applicator for only a short time, it is possible to prevent the resin within the applicator from being overheated and causing deterioration. In addition, the instantaneous application of resin is achieved by narrowing the gap between the sealing die and the drawing die rather than increasing the linear speed of the core wire, resulting in insufficient baking time in the baking oven, resulting in poor baking. It is possible to perform baking without causing any damage. Furthermore,
By narrowing the gap between the sealing die and the drawing die and instantaneously applying the resin, the residence time of the core wire in the applicator is shortened, so the preheating temperature of the core wire can be increased, and therefore the baking time in the baking furnace is reduced. The time required for baking can be further shortened, the baking furnace length can be further shortened, equipment costs can be reduced, and energy consumption within the furnace can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a schematic configuration of an apparatus for carrying out the method of the present invention, FIG. 2 is a sectional view showing an example of an applicator used in the apparatus, and FIG.
The figure is a characteristic diagram showing the relationship between resin application time and temperature rise. 1... Core wire, 4... Annealer, 5... Preheater, 6... Applicator, 7... Baking furnace, 1
3... Seal die, 14... Drawing die, 15
……resin.

Claims (1)

[Claims] 1 The core wire before entering the applicator is passed through a preheater to preheat it to a temperature higher than the temperature of the resin in the applicator, and then this high temperature core wire is passed through the applicator one after another to apply resin on its surface, and then passed through a baking furnace. In the method of manufacturing a resin-baked electric wire by baking the applied resin onto the core wire in the applicator, the resin is sequentially and instantaneously applied to the core wire by narrowing the interval between a sealing die and a drawing die in the applicator. Method for manufacturing resin-baked electric wire.