JPS6034763B2 - Manufacturing method of insulated wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing insulated wires, and in particular, by accurately controlling the viscosity of molten resin, there is less variation in coating thickness and thickness unevenness, and the appearance is good, the defect rate is reduced, and speed can be increased. A method for manufacturing an insulated wire is provided.

Conventionally, when applying and forming a thin resin coating layer on a wire rod, such as when manufacturing enameled wire, it is not common to apply pressure forcibly as in an extruder, but to apply a solvent to the resin. It is common to add or heat it to a molten state, apply it onto a wire while maintaining a desired viscosity, and then draw it with a die.

However, in this case, the viscosity control of the resin paint is generally controlled mainly by controlling the temperature of the resin paint bath and the child heat temperature of the wire rod.

However, in this case, due to changes in external temperature and temperature non-uniformity due to temperature gradients within the paint tank, the viscosity of the paint at the drawing die actually changes, resulting in poor appearance of the resulting insulated wire. This may cause uneven thickness (insulation failure).

For this reason, it is actually necessary to control the temperature of the die part itself where the paint is applied, but since it is difficult to use a crosshead for each piece due to multi-roll, low-speed processing, the next best option is to install a thermostat near the die. The temperature is detected by attaching a couple, but of course the temperature of the die itself is not detected and there is a large error. In particular, it was not possible to follow changes in the temperature of the wire rod itself to be coated.
Furthermore, attaching a thermocouple to a die makes the center of gravity of the die unbalanced and prevents free alignment due to being held in a floating state, resulting in uneven thickness.

In addition, the number of draws is large for one size, and the cost increases significantly because there are many books. The present invention was made to eliminate the above-mentioned drawbacks, and by controlling the secant of the molten resin viscosity at the die part, there is less variation in film thickness and thickness unevenness, and the appearance is good, the defect rate is reduced, and speed is increased. The purpose of this invention is to provide a method for manufacturing insulated wires that is possible.

The present invention involves heating a resin or adding a solvent to make the resin paint into a molten state, attaching it to the wire material to be coated, and applying it using a drawing die held in a floating state to form a desired coating film.
In the manufacturing method of insulated wire, in which the insulated wire is finished by baking it in a baking furnace, the drawing resistance applied to the varnish drawing die held in a floating state is continuously detected, the amount of change in the drawing resistance is converted into electrical output, and the heat source and feed to the solvent control circuit.
The present invention is characterized in that an insulated wire is manufactured while controlling the melt viscosity of the molten resin paint by back-coating.

Generally, when a high viscosity substance is attached to a wire and the wire is drawn with a die, it is known that the drawing force applied to the drawing die is proportional to the wire speed V and the viscosity of the paint.

According to the formula obtained by the inventor through experiments, F: Pulling force (
dyn) W: Pulling cart (g) Sword: Viscosity of molten material (CPS) V: Line distance (m/min) 1: Die gap length (side) Dd: Die inner diameter (skin) Dw: Wire diameter (side) ) Therefore, Da, 1 is constant once the die shape is determined,
Since V and Dw' are uniformly determined by the size and conditions of the strand to be processed, changes in the drawing load vary only by changes in viscosity.

Therefore, when the load applied to the die changes, this means that the viscosity of the resin paint passing through the die changes.By feeding this information back to the heat source and solvent control circuit for the molten resin, the viscosity of the resin paint passing through the die changes. Viscosity control can be performed. In fact, for example, 100q of almost solvent-free resin containing 90% or more of polyester resin
When performing dice coating while maintaining the PS viscosity at about 1000 to 200 by heating to a temperature of 0 or higher, if the molten resin is heated above a certain temperature limit, the reaction of the crosslinking agent contained therein will occur. This shortens the pot life of the molten resin liquid, and when the temperature drops by 1000, the viscosity increases approximately twice, resulting in poor appearance and uneven thickness.

Therefore, it is necessary to set the temperature to below ±5°C and the viscosity change to ±30%.

Therefore, in general, a drawing die with a load that will not sink when the viscosity is suitable is selected by calculating from the above formula, and as shown in the drawing, the die load is detected by a strain gauge 8, and this is converted into an electrical output, which is then connected to the resin liquid heating heater 6 and the wire rod. Feedback is provided to the control circuit of the subheater 7. That is, in the drawing, reference symbol 1 is a line to be coated, which is heated by a preheating heater 7, and a heated resin liquid 4 is deposited in a resin liquid tank 5 heated by a resin liquid heating heater 6. Ru. The die 3 squeezes the applied resin liquid 4 while being pushed upward by the viscosity of the resin liquid adhering to the wire, and the wire 1' coated with the resin liquid enters the drying furnace 9. In particular, when the resin tank 5 has an upper limit due to the deterioration temperature of the resin, when the temperature of the resin liquid 4 is below the upper limit, the resin tank heater 6
Further, above the upper limit point, the voltage or operation time of the wire preheating heater 7 is increased to always obtain a constant melt viscosity.

In the inventor's experiments, the molten resin liquid viscosity was 150 PS, the wire coating speed was 3 skins/min, and the die was
It took about 15 days for the sword to be drawn, and as shown in the drawing, it was amplified, detected by a strain meter 8, converted into an electric circuit, and an amplifier was installed to heat the resin liquid heater 6 in the resin tank 5 and the wire rod heater 7. feed back to the control circuit.

Additionally, it is of course also possible to feed back the converted electrical output to the solvent control circuit. As mentioned above, in the past, it was common to control the temperature of the resin liquid because the actual viscosity could not be controlled in the varnish drawing die part, but the temperature control part for the molten resin paint was not in the resin tank. Even in the supply source or the resin tank, there was a temperature difference because the mill and the die part were separated. However, in the present invention, no matter where the temperature control section is located, the viscosity is finally measured at the varnish drawing die, so accurate control can be achieved. In this way, the viscosity of the molten resin liquid applied to the wire rod is accurately controlled, resulting in insulated wires with good appearance and less variation in the insulation film thickness and uneven thickness of the resulting insulated wires, resulting in lower loss rates. This not only reduces the defect rate but also speeds up (improves efficiency).

Furthermore, since the heaters (namely, the resin liquid heating heater 6 and the wire rod ripening heater 7) can be controlled within an appropriate control range without overheating, there is also an effect of energy saving.

[Brief explanation of the drawing]

The drawings are explanatory diagrams of one embodiment of the present invention. 1... Wire rod, 1'... Wire rod to be coated, 2
...Die holder, 3...Dice, 4...Resin liquid, 5...Resin liquid tank, 6...Resin liquid heating heater, 7...Wire rod heater , 8... Strain meter, 9... Drying baking oven, 10... Liquid temperature measurement thermocouple.

Claims (1)

[Claims] 1 A resin paint made by heating the resin or adding a solvent to a molten state is attached to the wire rod to be coated, and is squeezed using a drawing die held in a floating state to form the desired coating film, which is then baked in a baking furnace. In the method for manufacturing finished insulated wires, the drawing resistance applied to the varnish drawing die held in a floating state is continuously detected, the amount of change in the drawing resistance is converted into an electrical output, and this is fed back to the heat source and solvent control circuit. A method for manufacturing an insulated wire, characterized in that the insulated wire is manufactured while controlling the melt viscosity of the molten resin paint.