Thermal Shock Resistance Evaluations of Brittle Tools by CO_2 Pulse Laser Beam Irradiation (Thermal Cracks in a Cemented Carbide Tool)

摘要

As a basis for establishing a method to evaluate the thermal shock resistanceof brittle tools, we irradiated CO_2 pulse laser beam on a cemented carbide tool to apply pure thermal shock and examined the states of thermal crack. The experiments were carried out on the condition of no melt on the beam irradiation surface. The crack appears at the beginning of the beam irradiation off time. Similarly in intermittent cutting, the crack is perpendicular to the cutting edge for the laser beam irradiation near the edge. The analyses of the temperature rise and thermal stress on the beam irradiation surface and in its neighborhood have demonstrated that no tensile stress appears on the surface, in the region below the surface, the stress field is uridely fornied where the three principal stresses are tensile, the primary principal stress is always tensile and becomes maximum immediately after the beam irradiation.