procedure and device for astadkommande of compact electric coils, was to hogtalare.

摘要

A method of producing a compact electric coil such as a voice coil for loudspeakers, whereby a coil member is wound of ordinary round wire having a coating of a thermoplastic or thermosetting bonding material, whereafter the coil member mounted on a mandrel is heated together with the mandrel and thereafter cooled from its outside so as to crimp around the mandrel while this is still warm and expanded. Hereby the round wire will be forced inwardly with high force so as to get cross sectionally deformed to fill out the available space to a very large degree, and the bonding material sets so as to hold the coil in its compacted shape whereby a coil of high rigidity and heat conductivity is produced. The coil is easily retractable from the mandrel upon further cooling of the latter.