PURPOSE: To obtain a shaft for transmitting driving force not broken easily even to large torque by forming a section tying the internal surface of the joining section of a pipe made of a fiber-reinforced resin and the straight pipe section of the internal surface of the pipe in a tapered shape having an inclination of 10° or less from the top section of a regular polygonal corner to the pipe straight pipe section.
CONSTITUTION: A section from the top section 9 of the corner of the regular polygonal section of the internal surface of a pipe 8 made of FRPs to a pipe straight pipe section is formed at an inclination of 10° or less. On the other hand, the internal and external surfaces of the joining section 2 of the pipe 8 made of FRPs can be reinforced by FRPs. It is desirable that the joining section 2 is reinforced from the balance of lightening, strength and profitability. The reinforcement of the joining section 2 of the pipe 8 made of FRPs is started from the straight pipe section including a tapered section. It is favorable that the reinforcement starting point 11 of the external surface of the straight pipe section of the pipe made of FRPs is kept within 5mm from the end 10 of the straight pipe section of the internal surface of the pipe.
YAMATSUTA KOJI
NAKANOU YOSHIFUMI
SHINOHARA YASUO
