| 摘要 |
PURPOSE:To prevent the partial wear in tip end grinding and at the same time to make the increase of fatigue resistance possible, by a method wherein the tip end of a printing wire is hardening treated to the core and its rear is not hardening treated or otherwise, the thickness of the hardened layer is limited. CONSTITUTION:High speed tool steel thin wire 1 is set in the V-shaped groove of a flat plate 20 so that the tip 2 is protruded by about 2mm. and further, flat plates are piled and fixed with bolts. After sufficiently washing the tip, it is treated by ion nitriding. Thereby, the nitriding layer is formed at the tip 2 of about 2mm. to the core and the thickness of the nitriding layer is gradually decreased at the rear part 9 therefrom. Though the wire becomes of high hardness of 1,100 in HV level to about 1.5mm. from the tip, when the bar exceeds about 2.5mm. from the tip, it becomes of the same hardness as the hardness of ordinary quenched tempered high speed tool steel of about 830 in HV. Thus, the generation of the tip partial plane wear in grinding is prevented and the fatigue resistance can be raised. |
