| 摘要 |
PROBLEM TO BE SOLVED: To improve durability, by suppressing chipping and a crack, by relieving stress concentration of a notch part formed by surface roughening, in a rolling flat die for securing grip force by the surface roughening of a surface by blast treatment.SOLUTION: Since the blast treatment is executed by using a comparatively large blast abrasive grain 44 within a range of 0.1-0.5 mm in a particle diameter for a biting front side part 34 of a rolling molding surface 22, the surface is roughened in large surface roughness, and excellent grip force is provided when executing rolling processing, and sliding when a processing tooth 20 bites in a workpiece 14 is properly prevented. Since shot-peening is executed by using a very small shot 50 having a particle size within a range of 50-100 μm after the blast treatment, while maintaining large surface roughness by the blast treatment, the stress concentration is relieved by imparting roundness to a bottom of a notch 46, and the durability is improved by suppressing the occurrence of the chipping and the crack. |
