GEAR PART AND MANUFACTURING METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a compact and weight-reduced gear part through the integration of a gear member and a rotary member, and a mass productive manufacturing method for the gear part. SOLUTION: In a manufacturing method for the gear part comprised of the gear member and the rotary member, an intermediately formed work 5 is formed in a first process, which is comprised of the rotary member 3 and a preliminary form 5a for the gear member with its side profile in a shape of a hand drum. In a second process, while the rotary member 3 is cramped from four directions with cramping metal dies 8, the intermediately formed work 5 is axially compressed to form the gear member 2 with an upper metal die 7 and a lower punch 10, which have compressing parts 7a, 10a for the inside of a material respectively. In those steps, the gear part is integrally formed by forging. The forming process prevents a folding defect or the like without causing lapping of material in filling into a tooth space 12 so that it enables the mass production of gear part such as a load sheave and a pinion gear which contribute to the miniaturization and weight reduction of a machine such as a chain block.