Electromagnet with armature between two separate pole shoes - using electroless plated armature and shoe surfaces magnetically separated by spacer ring

摘要

The electromagnet comprises an armature which slides between two sleeve-like pole shoes which are magnetically separated from each other by a spacer ring. On the inner surface of the pole shoes and on the surface of the armature is a thin layer of magnetically non-conducting material which is applied chemically. The thin layers may consist of Ni or Cr, or the surface of the pole shoes may be nickel-plated and the surface of the armature Cr-plated. The thickness of the layers is pref approx 15mu. The Nilayers may be hardened thermally. The electromagnet may be used for control of the printing needles of a mosaic printer, because increases in stroke and wear of the tips of the printing needles by the printing process do not have a direct effect on the working life of the printer.