| 摘要 |
A U-shaped wound core for heat activating the adhesive layer 40 of a ferromagnetic fastener 34 when the ferromagnetic base 36 of the fastener bridges the legs 14 of the core to complete the magnetic flux circuit, is thermally decoupled from the base by spacers provided between the end forces 18 of the core and the surface of the base 14. The spacers may be provided by rods 28, 29 secured to the end faces 18 of the legs of the core, by coatings on the end faces of the core, by lines of projections formed on the ferromagnetic base of the fastener, or by upturned marginal edges of the ferromagnetic base of the fastener. To compensate for differential heat loss from the ferromagnetic base covered with adhesive e.g. by a marginal tab on the fastener, the spacers may be of different thicknesses so than one leg of the core is more closely magnetically coupled to the base of the fastener than the other. <IMAGE> |
