GB506799A - Improvements in or relating to production of iron dust cores - Google Patents

Abstract

506,799. Magnetic dust cores; moulding. VOGT, H. Dec. 1, 1937, No. 33255. Convention date, Dec. 1, 1936. [Class 38 (ii)] [Also in Group V] Cores for highfrequency coils are produced by pressure moulding magnetic dust and a hinder to approximately the finished shape and density, and then subjecting the provisionally moulded article while in a slightly plastic state to further pressure in a final mould whereby any intricate formations such as screw-threads required on the finished article are formed. For example, the screwed adjusting pin of a cotton-reel type core is produced by first compressing a mixture of iron dust and a binder such as phenol- or urea-formaldehyde into a plain cylinder which is partially hardened and then placed in a split mould 6 consisting of two parts hinged together at 7. The parts of the mould are internally threaded and held together by the walls of a recess in a swiveling plate 4 which may contain a series of recesses for other moulds. Final moulding pressure is applied by a plunger 8. which may have a rib 11 for forming a screw-mivex slot in the end of the core pin. A heating coil 5 may be provided where the binder used requires heat for softening. After moulding, the mould 6 is ejected by the ram 10 and opened for removal of the core pin which is then finally hardened. The cotton-reel body of the core may be formed by provisionally moulding the three parts 12, 13, 14, Fig. 3, and uniting them and forming an internal thread therein by a final moulding operation in the partially hardened condition.