(57) A novel pencil core (20) constituted by a plurality of filaments (10) of a pencil
core material (2) individually having a thickness of 10 to 250 microns, and bundled
and joined together with a binder material (13). Such a pencil core (20) is manufactured
by (a) producing a semi-soft core material (2) of graphite and a synthetic resin,
(b) extruding said core material (2) through nozzles (4) to produce a plurality of
filaments (10), bundling said filaments (10) together in a ring (7b) into which is
forced a binder material (13) by a screw-feed device (7c-7m) to encase the filaments,
and (d) compressing the bundled and encased filaments (10) between rolls (9a, 9b)
to produce the finished pencil core (20). Heat-treatment is provided by various heaters
6a, 6b, 8).
|
|
