Method for manufacturing a fastening portion for a steering apparatus

A manufacturing method for a fastening portion for a steering apparatus which comprises:

• a shaft portion which transmits rotational torque inputted from a steering wheel to a rotational shaft;
• and
• the fastening portion which is integrally provided at one end of the shaft portion and comprises a non-circular hole to which a non-circular shaft portion at an end of the rotational shaft is fitted,
• the manufacturing method comprising:
• forming a preparation hole of which volume is larger than a volume of the desired non-circular hole in the fastening portion;
• forming a padding of which volume is equivalent to a difference between a volume of the preparation hole and the volume of the desired non-circular hole on an outer circumference of the fastening portion;
• inserting a punch of which shape of a non-circular outer circumference is the same as the shape of the desired non-circular hole into the preparation hole;
• and
• restraining the outer circumference of the fastening portion by a die of which an inner circumferential shape is the same as an outer circumferential shape of a desired fastening portion and pushing the padding into the preparation hole so as to make the preparation hole to the desired non-circular hole.