JPS5839008A - Manufacture of coil - Google Patents

Abstract

PURPOSE:To provide high-reliability, improved-performance insulating layers on both the inside and outside of a coil by a method wherein adhesion free of void is ensured between a transformer and a coil main body through utilization of the heat-caused shrinking force of a heat-shrinking fabric base material. CONSTITUTION:An insulating sheet A of a prescribed insulation thickness is wound, with its half-hardened thermosetting resin layer facing outside, about a core metal. Metal foil and insulating film are wound together on said insulating sheet A, for the formation of a coil main body. Then the coil main body is wound about with an insulating sheet B with a prescribed insulating thickness. A preheating follows for a prescribed period. In this period, contact between the wound insulating sheet A and the coil main body and that between the wound insulating sheet B and the coil main body are established voidless thanks to heat-caused contraction under pressure. The core metal is taken out when the heating is over. The coil main body is then subjected to another heating, this time for the complete hardening of the half-hardened resin. No stress is expected to result from hardening and shrinking now that the core metal has already been removed, which eliminates difficulties encountered in taking out a metal core and abnormalities caused by the resin layer in its hardening process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a coil, and is particularly useful for manufacturing a transformer coil.

In a transformer coil, high electrical stress acts on the inner and outer surfaces of the coil, so it is necessary to cover it with reliable, high-performance insulation.

For this reason, the present inventors wound an insulating sheet A, which has a semi-cured thermosetting resin layer on at least one side, onto a core metal with the semi-cured thermosetting resin layer as the outer surface, and then wound a coil body thereon. The insulating sheet B, which is a heat-shrinkable fiber base material impregnated with a thermosetting resin in a semi-cured state, is wound around this coil body, and then the wound layer of the insulating sheet A and the insulating sheet B are heated. The inventor devised a method of completely curing the semi-cured thermosetting resin of each of the wound layers.

According to this method, during heating, the insulating sheet B thermally shrinks, and the above-mentioned insulating sheet C) Pressure is generated as stress due to the thermal contraction force of B. Therefore, when the semi-cured thermosetting resins of insulation sheet A and insulation sheet B are in a molten state as a stage before complete curing, due to this molten state and the above pressure, the insulation sheet The void-free adhesion between the winding layer of A and the coil body and the void-free adhesion between the winding layer of insulating sheet B and the coil body are well guaranteed, and the inner and outer surfaces of the coil body are A reliable and high performance insulating layer can be provided.

The above-mentioned insulation treatment method is intended to improve the so-called insulation treatment using the known prepreg by making the insulation layer completely void-free by utilizing the heat shrinkage force of the heat-shrinkable fiber base material. Superior reliability and high performance can be expected compared to prepreg insulation treatment.

However, in the above-mentioned improved insulation treatment method, the core metal is in an immovable state where it cannot absorb the curing shrinkage that occurs while the thermosetting resin in the semi-cured state is completely cured. Therefore, there are problems in that abnormal stress is generated due to curing shrinkage, causing abnormalities in the thermosetting resin layer and making it extremely difficult to remove the core metal.

The method for manufacturing a coil according to the present invention is a method invented in order to solve the above problem, and in which an insulating sheet A having a semi-cured thermosetting resin layer on at least one side is formed into a semi-cured thermosetting resin. It is wound on a core metal with the resin layer as the outer surface, a coil body is provided on it, and an insulating sheet B in which a heat-shrinkable fiber base material is impregnated with a thermosetting resin in a semi-cured state is wound thereon, Next, the pre-heating is performed to completely heat-shrink the wound layer of insulation sheet) B, and due to the heat shrinkage force, the thermosetting resin of insulation sheet) A, the coil body, and the thermosetting resin of insulation sheet B are bonded together. This method is characterized in that the coil body is bonded to the coil body under pressure, the core bar is then removed, and the thermosetting resin of both the insulating sheets A and B is completely cured by heating at a later stage.

The above-mentioned insulating sheet A is made of a thermosetting resin-impregnated fiber base material with a semi-cured epoxy resin layer on one or both sides. Cloth or non-woven fabric, polyester woven fabric or non-woven fabric, aramid paper, asbestos paper, etc. can be used, and thermosetting impregnated resins such as polyimide, polyamide, polyoxadiazole, aromatic polyamide, silicone, epoxy resin, polyester resin, etc. can be used. can.

The metal foil that makes up the coil body can be aluminum foil, copper foil, etc., and the insulating film can be polyimide film, aluminum foil, etc.
)-ester film, aromatic polyamide paper can be used. A prepreg layer (semi-cured thermosetting resin layer) can also be provided on this insulating film or metal foil.

The heat-shrinkable fiber base material of the insulation sheet) B includes heat-shrinkable polyester fiber (heat shrinkage rate 5-15%) in the warp threads.
A mixed woven fabric in which glass fiber is used for each weft can be used.

The present invention will be explained below.

To carry out the present invention, first, the above-mentioned insulating sheet A is wound to a predetermined insulation thickness on a core bar whose surface is coated with a mold release agent, with the semi-cured thermosetting resin layer as the outer surface. In this case, it is also possible to use an insulating sheet provided with semi-cured thermosetting resin layers on both sides.

After winding the insulating sheet A, a metal foil and an insulating film are wound together on top of it to form a coil body, and the above-mentioned insulating sheet B is wound on this coil body to a predetermined insulation thickness. .

Next, the semi-hardened thermosetting resin of the insulating sheet A and the insulating sheet B is melted into the coil body obtained as described above,
In addition, the insulation sheet) B is pre-heated at a temperature at which the heat-shrinkable fiber base material of B is heat-shrinked for a predetermined period of time. Due to this preliminary heating, the heat-shrinkable fiber base material of insulation sheet B is thermally shrunk, and the semi-hardened thermosetting resin layers of insulation sheet A and insulation sheet B are temporarily in a thermally molten state. To,
Due to the heat shrinkage force, the wound layer of the insulating sheet A and the coil body are bonded together under pressure in a void-free state, and the wound layer of the insulating sheet B and the coil body are bonded together under pressure.

After this preliminary heating, the core metal is removed, and then the coil body is heated to completely cure the semi-cured resin of each of the wound layers of insulating sheet A and the wound layer of insulating sheet B. . Curing shrinkage occurs during this curing process, but since the core metal has already been pulled out at this stage, there is virtually no stress caused by the curing shrinkage, which may make it difficult to pull out the core metal or cause abnormalities in the cured resin layer. You can avoid the disadvantages that may arise.

After the above-mentioned curing is completed, the coil body is cut into rings to a predetermined size, thereby completing the production of the coil.

Example Insulating Sheet A Epoxy varnish (
TvB 2024 (manufactured by Toshiba Chemical Co., Ltd.) was applied and heated to a semi-cured state at 130°C for XIO minutes. The finished thickness is 0.5t+a.

Insulation sheet B Heat-shrinkable polyester fiber (manufactured by Teijin Co., Ltd., BH-250 singleton) is used as warp thread, glass fiber (manufactured by Nippon Glass Fiber Co., Ltd.,
KOG-75, 110-1:OZ) is used as the weft yarn, warp yarn density is 40/725, weft yarn density is 35/25
Epoxy resin liquid [epoxy resin (product name: Dgu-438) manufactured by Dow Chemical Company: 760 parts by weight, epoxy resin (product name: EP-1001) manufactured by Shell Chemical Company: 40 parts by weight,
BIFJ-monoethylamide complex: 3 parts by weight dissolved in a mixed solution of methyl ethyl ketone and doluol 1:1 at a weight ratio of 50 (sub)) was impregnated into a semi-cured state by heating at 80'CX for 30 minutes. use things. Finished thickness is 0.2
It's 5 fights.

The above insulating sheet A with a width of 900 fins was wound twice on an iron core metal with an outer diameter of 300 mmφ and a length of 1000 m with silicone grease baked on the surface, and a polyester film (thickness: 0.05 m5) and aluminum were placed on top of it. Foil (thickness: Q, 5m
5) was wound 20 times, and on top of that, the above-mentioned insulating sheet B having a width of 50 mm was wound 4 times in half 5 x 7' LIC.

Next, this coil body was pre-heated in a heating furnace at 130° C. for 5 hours, allowed to cool to room temperature, the core metal was removed, and post-heated again in a heating furnace at 130° C. for 10 hours.

It was easy to remove the core metal after the above-mentioned pre-stage heating, and both the wound layer of insulating sheet A and the wound layer of insulating sheet B after the post-stage heating were void-free and no abnormality was observed. Ta. Then, when we conducted a long-term heat resistance life test including a heat cycle test, a vibration test, and a moisture resistance test, it was confirmed that all items passed the heat resistance class B standard.

Claims (1)

[Claims] (1) Insulating sheet A with a semi-cured thermosetting resin layer provided on at least one side is wound around a core metal with the semi-cured thermosetting resin layer on the outer surface, and a coil body is provided on top of it,
On top of that, an insulating sheet B impregnated with a thermosetting resin in a semi-cured state is wound around a heat-shrinkable fiber base material, and then the wound layer of the insulating sheet B is completely heat-shrinked by pre-heating.
The heat shrinkage forces the thermosetting resin of the insulation sheet A and the coil body, as well as the thermosetting resin of the insulation sheet B and the coil body, to be bonded together under pressure, and then the core metal is removed, and by heating in a later stage, A method for manufacturing a coil, characterized in that curing of the thermosetting resins of both insulation sheets A and B is completed.