パルス状CO_2レーザビーム照射による脆性工具の耐熱衝撃性評価(超音波顕微鏡による熱き裂の観察と熱応力に及ぼす球状微小空孔の影響)

概要

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As a basis to establish a method for evaluating the pure thermal shock resistance of brittle tools without applying cutting forces, a study was carried out about the starting point of the thermal crack by a method in which CO_2 pulse laser beam is irradiated on the rake face of a cemented carbide tool. The method is an original one recently proposed by the authors. Observations using a scanning acoustic microscope have demonstrated that thermal cracks not confirmed on the irradiation surface exist beneath the surface. The influence of the internal defects such as pore and so on, the fields of thermal stress was analyzed setting a spherical minute pore beneath the surface. The maximum main principal tensile stress, which occurs on the pore surface, increases rapidly after the start of the irradiation and maintains a higher level during the irradiation. The stress is markedly high beneath the irradiation surface. From these results, the thermal cracks on the rake face due to the irradiation may have originated from the internal defects beneath the irradiation surface.
2001-03-25