JPH02132812A - Manufacture of resin-molded coil - Google Patents

Abstract

PURPOSE:To suppress the generation of corona discharge and to contrive improvement both in quality and reliability by a method wherein, after the wire coating film of a coil has been coated with a mold-releasing agent, a resin molding operation is conducted. CONSTITUTION:A plurality of split coils 3a to 3f are laminated successively against a lower flange metal mold 1a and an inner circumferential side metal mold 1b through the intermediary of a spacer 2. The coils 3a to 3f are constituted by winding a wire 5, having a coating film 5a such as enamel and the like, the prescribed number of turns without using a interlayer insulating material, and besides, the coils 3a to 3f are dipped into a mold-releasing vessel and the coating film 5a of the wire 5 is coated with a mold-releasing agent. Then, the coils 3a to 3f are electrically connected, an external metal mold 1c and an upper flange metal mold 1d are arranged from outside, and a coil assembly A is constituted. This assembly A is set in a vacuum treatment tank, it is heated up, resin is poured in the tank from a filling hole in a vacuum state, they are heated up and gradually cooled down, and a resin-molded coil is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing a resin molded coil used in a transformer.

(Prior Art) As a resin molded coil used in a transformer, there is one in which a plurality of divided coils are assembled and resin molded. This is because by configuring a plurality of coils, the voltage shared by each coil can be reduced, and the voltage shared between turns of each coil can also be reduced, so that it is possible to save labor for insulation. A method for manufacturing this type of resin molded coil will be described below. First, an insulated membrane electric wire is wound around a disc-shaped lower flange mold and a cylindrical inner peripheral mold through a spacer made of the same material as the casting resin, without providing any interlayer insulation. The divided coils with the given number of antinodes are sequentially stacked. After each coil is electrically connected, a cylindrical outer peripheral mold is placed from the outside of the divided coils, and a disk-shaped upper flange mold is placed. In addition,
The mating surfaces of each mold are sealed. After this, this coil assembly is set in a vacuum processing tank, heated and vacuumed,
Polyester resin, epoxy resin, or other resin is poured into the mold through the resin injection port. After this casting, the coil assembly is transferred to another processing section where it is heated and slowly cooled to complete the resin molded coil.

(Problems to be Solved by the Invention) By the way, when the resin molded coil is incorporated into a transformer and used, cracks may occur due to the difference in thermal expansion between the resin and the coil's electric wire due to temperature changes during use. In this case, since the coating of the electric wire is adhered to the resin, this coating may be peeled off. If this happens, this type of coil, which is mainly insulated by an insulating film, will have a significant reduction in insulation, which may lead to corona discharge and dielectric breakdown.

The present invention has been made in view of the above circumstances, and the present invention has been made in view of the above circumstances.
One object of the present invention is to provide a method for manufacturing a resin molded coil, which can suppress the occurrence of corona discharge and improve quality and reliability.

[Structure of the Invention] (Means for Solving the Problems) The method for manufacturing a resin-molded coil of the present invention is characterized in that a release material is applied to the wire coating of the coil, and then the coil is resin-molded.

(Function) According to the above means, since a release agent is applied to the wire coating of the coil in advance before resin casting, the wire coating and the casting resin are not in a hard state.

Therefore, even if cracks occur due to temperature changes during use when a resin molded coil is installed in a transformer,
The wire coating of the coil will not peel off from the wire. As a result, corona discharge is prevented from occurring.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

ffi2 As shown in FIG. 2, a plurality of divided coils 3a to 3f are sequentially stacked on the lower flange mold 1a and the inner peripheral mold 1b via spacers 2, . . . . As shown in FIG. 1, each of the divided coils 3a to 3f is constructed by winding a predetermined number of electric wires 5 having a film 5a made of enamel or the like without using an interlayer insulator, and each of the divided coils 3a to 3f is A mold release agent (not shown) is applied to the membrane 5a of the electric wire 5 by dipping it in a mold release agent (not shown).

Thereafter, the coil assembly A is constructed by electrically connecting the divided coils 3a to 3f, arranging the outer circumferential mold 1c from the outside, and arranging the upper flange mold 1d. next,
This coil assembly A is set in a vacuum processing tank, and a resin 4 such as polyester resin or epoxy resin is poured into the mold through a resin injection port (not shown) under heating and vacuum conditions. After this casting, the coil stand A is transferred to another processing section or heated and slowly cooled in the same tank to complete a resin molded coil. Note that the molds 1a to 1d may be used as they are to produce a product, or may be removed to produce a product.

In the above purchasing, each divided coil 3a to 3f is t
Since the mold release material is applied to the film 5a of the line 5, the film 5
a and the resin 4 after hardening are not in a solid state, and as a result, even if cracks occur in the resin 4 around the coil '3f due to temperature changes during use, the membrane 5a of the electric wire 5 of the coil 3f will not The electric wire 5 will not be peeled off. As a result, the insulation provided by the coating 5a is not impaired, so that corona discharge is prevented from occurring.

Furthermore, since the electric wires 5 of the coils 3a to 3f and the resin 4 communicate with atmospheric pressure, even if a crack occurs in the resin 4, the pressure inside the crack becomes atmospheric pressure.
Therefore, the corona generation voltage can be suppressed according to Bassien's law, making it more effective in preventing corona generation.

In the above embodiment, the electric wires 5 of the split coils 3a to 3f and the resin 4 are kept in communication with the atmosphere, but after the resin molding, the split coils 3a or 3f
A putty-like filler may be filled around the lead wire to prevent dust, moisture, etc. from entering the resin molded coil.

[Effects of the Invention] According to the method of manufacturing a resin molded coil of the present invention, even if cracks occur in the resin, it is possible to reliably prevent the wire coating of the coil from being peeled off, thereby preventing the occurrence of corona discharge. As a result, the quality and reliability of the resin molded coil can be improved.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 being a longitudinal cross-sectional view of a divided coil, and FIG. 2 being a longitudinal cross-sectional side view of a resin molded coil. In the figure, a to d are molds, a to 3f are divided coils, and 4 is resin.

Claims (1)

[Claims] 1. A method for producing a resin-molded coil, characterized in that the coil is resin-molded after applying a mold release material to the wire coating of the coil.