| 摘要 |
PROBLEM TO BE SOLVED: To provide a pipe type ball-point pen tip on which a punching process can properly be applied although an ultra-small ball is installed, and in addition, which can sufficiently suppress the abrasion of a ball receiving seat. SOLUTION: On the distal end of a metal pipe 2, a tapered edge section 3 having a tapered surface 31 on the external surface is formed. On a straight cylindrical side wall behind the edge section 3 of the tubule, a plurality of inward protruding sections 4 for the ball receiving seat are formed by the punching process. On the internal surface in a vicinity of the distal end of the pipe 2, a caulking section 5 is formed by bending the distal end of the edge section 3 of the pipe 2 inward into a circumferential shape. A ball 6 is rotatably embraced by the ball receiving seat and the caulking section 5. When the outer diameter of the ball is represented by A, the diameter of a virtual inscribed circle coming into contact with the top-most vertices of the inward protruding sections 4 is represented by B, and the thickness of the pipe is represented T, the relations, "0.15 mm≤A≤0.29 mm", "1.8≤A/T≤3.5" and "0.5≤B/T≤1.5" are satisfied. COPYRIGHT: (C)2006,JPO&NCIPI
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