To provide a core material pitch varying method improved so as to be capable of varying the core material pitch in the fiber reinforced cord in a state made as uniform as possible in a direction arranging in a row.
In the core material pitch varying method, a pitch variable roll R, wherein a right-hand male screw like forward ridge spiral 1 and a left-hand male screw like reverse ridge spiral 2 are formed on the outer peripheral surface of a roll member (r) in adjacent relationship, is prepared and a wide belt like fiber reinforced cord 5, which is formed by coating a plurality of core materials 3 arranged in parallel with a rubber 4 is wound around the pitch variable roll R in a heated state to be relatively slid and fed while the winding angle to the pitch variable roll R is controlled so as to be allowed to follow the feed distance of the fiber reinforced cord 5.
OSHIKATA MITSUO
UETSUBO KAZUHARU
Toshiyuki Kimura