| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently ensure flow rate of ink and to solve a problem such as straight flow, air entrainment, omission or ball flying by increasing a rear end side inner diameter of a finishing inner wall of a receiving seat side from an end side inner diameter of a finishing inner wall as a cylindrical wall of a ball in a lateral direction in a tip. SOLUTION: A writing ball 1 is release-inhibited by a receiving seat 16 at a rear end side by caulking 3 at a front end side at an end of a tip, and the ball 1 is rotatably loosely engaged in the state with vertical looseness in a longitudinal direction. Here, an end side inner diameter T of a cylindrical inner wall 17 between the caulked part 3 in the tip and the seat 16 and s size between a rear end inner diameter U is set to satisfy T<U. This shape is formed, and hence a sealing surface 8 side of its end is set relatively narrow. Accordingly, a problem such as straight flow can be solved. And, since a large ink channel can be obtained at the rear end side, flow-out amount of ink to affect density or wear of a drawing line can be sufficiently obtained. |
