Gear made of fiber reinforced resin and method for manufacturing same

摘要

A gear made of fiber reinforced resin which is capable of being increased in durability and mechanical strength, as well as gear cutting characteristics. The gear is manufactured by arranging ring-like reinforcing fiber substrates and a metal bushing in a molding die and pouring thermosetting resin into the die to impregnate the reinforcing fiber substrates with the resin. The reinforcing fiber substrates are made by winding up a cylindrical body obtained by knitting an aramid fiber yarn along a central line thereof and then forming it into a ring-like shape. The reinforcing fiber substrates are pressed in a cold die so as to approach to a shape of the molding die, to thereby be formed into a rectangular shape in cross section. Then, the reinforcing fiber substrates are received together with the metal bushing in the molding die and then the thermosetting resin is poured into the molding die. The reinforcing fiber substrates each have a volume percentage of 30 to 65% and preferably 45 to 55% based on a volume of a resin molded member. A para-type aramid fiber and an organic fiber reduced in strength as compared with the aramid fiber are blended together to form a union yarn. The para-type aramid fiber has a mass percentage of 30% to 60% by mass and preferably 40% to 50% by mass based on a mass of the union yarn.