| 摘要 |
PROBLEM TO BE SOLVED: To enhance writability without slack trend of ink discharge with hardly causing recess of ball seat or wear by high writing pressure by forming a tip body of a ballpoint pen tip obtained by protruding a part of a ball from an end and rotatably holding it of specific material. SOLUTION: A tip body 1a is formed by using a ferrite stainless steel material containing 0.80 to 2.00wt.% of silicon and 19 to 21wt.% of chromium. This steel material is increased at a mixing ratio of the silicon in 20 Cr material. Since the ratio of the silicon is increased, strength of the material is improved, wear performance by writing pressure of high load observed in the case of writing a copy cut form is improved, and rotation of a ball 2 becomes smooth. As the ball 2, tungsten base cemented carbide ball or ceramic ball can be used. |
