JPH0578125B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for manufacturing rectangular insulated wires by electrostatic powder coating. [Technical background of the invention and its problems] In recent years, the method of manufacturing insulated wires using powder coating has been attracting attention from the viewpoints of pollution-free, resource-saving, and energy-saving, and among these methods, this method has the highest coating efficiency. , the electrostatic dynamic dipping method is particularly gaining attention in the field of insulated wire manufacturing. In this method, for example, charged synthetic resin powder is fluidized by dry air passing through a perforated plate placed below to form a fluidized bed, and a metal conductor is filled with the synthetic resin powder above this fluidized bed. This is a method in which the synthetic resin powder is electrostatically attached to the surface through the coating zone, and then the attached synthetic resin powder is heated and fused and cured to form a coating. A method is used to pass the In this method, the thickness of the film formed on the conductor is controlled by the charging voltage applied to the synthetic resin powder, the amount of air sent in to fluidize the powder, and a coating amount adjusting plate. However, it was not possible to obtain a stable film thickness over a long period of time, and in the case of rectangular conductors, it was difficult to equalize the film thickness at the corners and flat parts. [Purpose of the Invention] The present invention has been made to solve these problems, and it is an insulated wire that has a coating of uniform thickness over the entire circumference and has high electrical properties, especially dielectric breakdown voltage. The purpose is to provide a method for [Summary of the Invention] That is, the method of manufacturing a rectangular insulated wire using the electrostatic powder coating method of the present invention involves passing a conductor through a coating chamber filled with charged synthetic resin powder, and coating the surface of the conductor with the synthetic resin powder. A process of attaching the conductor to the conductor, followed by a process of melting the synthetic resin powder adhered to the conductor with a heating device at a temperature of 150°C or less, immediately passing it through a die, and further passing it through a heating furnace. It is characterized by consisting of a step of curing. As a heater in the present invention, as a result of heating the synthetic resin powder from the conductor side, it is possible to prevent bubbles from forming in the coating film, so heating here increases the viscosity of the molten synthetic resin. It is necessary to keep the temperature below 150℃, which can be ignored. It is more preferable that the melting temperature is lower, and more preferable results can be obtained if the melting temperature is set to 100°C or less. In addition, the reason why the synthetic resin powder is passed through the die immediately after passing through the heater is because the temperature of the molten synthetic resin rises and the viscosity increases rapidly after the die is placed on the heating furnace side. This is because it becomes difficult to control. [Embodiments of the Invention] FIG. 1 is a diagram schematically showing an apparatus used in the method of the present invention, in which a rectangular copper wire 2 sent out from a wire supply device 1 is coated on its surface in a coating chamber 3. The charged synthetic resin powder is deposited, then melted in a high frequency induction heater 4, and immediately squeezed by a die 5 placed in contact with the high frequency induction heater. Furthermore, heating furnace 6
The molten synthetic resin is hardened by passing through, and after being cooled in a cooler 7, it is wound up in a winding device 8. Examples of the present invention using the above-mentioned apparatus will be described below. Example As shown in the drawing, Scotchicast (trade name of epoxy resin powder manufactured by 3M, USA) charged with a charging voltage of -65 kV was applied to a perforated plate at a rate of 300/min in a coating chamber 3 with a length of 70 cm. It was fluidized by the dry air that passed through at a flow rate, and a fluidized bed was formed at the bottom of the coating chamber. A rectangular copper wire 2 of 2.0 x 5.0 mm was passed horizontally about 10 cm above this fluidized bed at a speed of 3.0 m/min to deposit the charged Scotchicast on the surface. Next, the rectangular copper wire 2 to which Scotchicast was attached was passed through a high-frequency induction heater 4 and heated to below 150°C, then squeezed with a die 5, and further heated to a furnace temperature of 400°C.
The Scotch cast was cured by passing through a heating furnace 6 at ~450°C and a furnace length of 3.5 m. The thickness of the insulating coating of the rectangular insulated wire thus manufactured was measured at the position shown in FIG. 2, and is shown in the following table. In the figure, 10 indicates a rectangular conductor, and 11 indicates an insulating coating. In addition, the comparative example shown in the table is the measurement result by a conventional method that does not use a high-frequency induction heater and a die, and shows the case of manufacturing under the same conditions as the example.

[Table] [Effects of the Invention] As is clear from the above examples, according to the present invention, an insulating film with a uniform thickness is formed all around the conductor, and therefore the electrical and mechanical properties are improved. It is possible to manufacture insulated wires with excellent properties.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of an apparatus used in the method of the present invention, and FIG. 2 is a sectional view of a rectangular insulated wire showing the measurement position of the insulation coating. 2...Flat copper wire, 3...Painting room, 4...High frequency induction heater, 5...Dice, 6...Heating furnace, 10
... Rectangular conductor, 11 ... Insulating coating.

Claims (1)

[Claims] 1. A step in which a conductor is passed through a coating chamber filled with charged synthetic resin powder to adhere the synthetic resin powder to its surface, and then a heater is used to adhere the synthetic resin powder onto the conductor. Electrostatic powder coating is characterized by comprising the steps of melting synthetic resin powder at a temperature of 150°C or less and immediately passing it through a die, and then passing it through a heating furnace to harden it. Method for manufacturing flat insulated wire by method. 2. A method for manufacturing a rectangular insulated wire using an electrostatic powder coating method according to claim 1, wherein the heater is a high-frequency induction heater.