| 摘要 |
<p>PURPOSE:To prevent the occurrence of corona discharge by a method wherein an uneven layer of thermohardening resin is provided on the external surface of a coil so that adhering force to the rubber member is increased. CONSTITUTION:A layer 3 of resin which is semi-dry at normal temperature is provided on an iron core 1 and coils 2a, 2b, and a knurling is applied to the external surface so as to copy the unevenness 4, then the layer is heated and hardened. Next, the layer is coated with liquid rubber which readily wets with the unevenness 4. As a rubber coating material, the most suitable one is a thermosetting polymer consisting of a liquid polybutadiene with 50% or more of hydrogenation ratio, 1.7-2.4 of the average number of hydroxyls, and 1,000-8,000 of mean molecular weight; an isocyanate compound; and inorganic fillers. When the layer of resin is half-hardened, powder such as quartz having a grain size of 100-1,000mum may be sprayed in order to form an uneven surface. With this constitution, the adhesive strength of the rubber member is strengthened, thus preventing the occurrence of corona discharge due to exfoliation.</p> |
