Core-discs, Segmental.
Core-discs made in segments, which are bolted together to form a
complete disc or section of the core. The plan is adopted principally on
large cores. The discs thus made up are placed together to form the core
exactly as in the case of ordinary one piece discs.
Fig. 114. PIERCED OR PERFORATED CORE-DISC.
Core-discs, Toothed.
Core-discs of an armature of a dynamo or motor, which discs are cut into
notches on the periphery. These are put together to form the armature
core, with the notches corresponding so as to form a series of grooves
in which the wire winding is laid. This construction reduces the actual
air-gaps, and keeps the wires evenly spaced. Distance-pieces of
box-wood, m, m, are sometimes used to lead the wires at the ends of the
armature.
Fig. 115. TOOTHED CORE-DISC.
Core, Laminated.
A core of an armature, induction coil or converter or other similar
construction, which is made up of plates insulated more or less
perfectly from each other. The object of lamination is to prevent the
formation of Foucault currents. (See Currents, Foucault.) As insulation,
thin shellacked paper may be used, or sometimes the superficial
oxidation of the plates alone is relied on. The plates, in general, are
laid perpendicular to the principal convolutions of the wire, or
parallel to the lines of force. The object is to break up currents, and
such currents are induced by the variation in intensity of the field of
force, and their direction is perpendicular to the lines of force, or
parallel to the inducing conductors.
A core built up of core discs is sometimes termed a tangentially
laminated core. Made up of ribbon or wire wound coil fashion, it is
termed a radially laminated core.