| 摘要 |
PROBLEM TO BE SOLVED: To provide a coupling structure which has high peeling strength.SOLUTION: A lift arm 5 includes a through tapered hole 35 having a first inner wall part 33 formed through work hardening by plastic deformation, a swell part 45 having an inner wall surface 41 connecting with the inner wall surface 31 of the through tapered hole 35 and having a second inner wall part 43 formed through work hardening by plastic deformation, and a recessed part 67 formed on a lower surface with a projection provided to a lower die, and a driven gear 3 includes an outer wall part 53 which is fitted up to the swell part 45 from the through tapered hole 35 and formed through work hardening by plastic deformation, and a projection part 51 having an outer wall surface 55 brought into contact with at least a part of the inner wall surface 41 of the swell part 45. |
