Research on the mechanism of particle deposit effects and process optimization of nanosecond pulsed laser truing and dressing of materials

Abstract

New plasma expansion models and change rate models of plasma excitation were established under cylindrical coordinates. Expansion models were used to numerically analyse the plasma expansion characteristics of the nanosecond pulsed laser truing and dressing of a bronze–diamond grinding wheel (LTDBDGW). The results showed that the plasma expansions in the X- and R-directions were approximately 8 × 10⁻⁴ m and 2.5 × 10⁻⁴ m, respectively. The plasma electron density calculated by the results was 1.0757 × 10¹⁶ cm⁻³. The calculation of the change rate models of the plasma excitation shows that the plasma excitation mechanism of LTDBDGW was controlled mainly by the thermal excitation effect. In response to high-temperature and high-speed collisions, black particles deposit onto the surface of the bronze–diamond grinding wheel, affecting the topography of the surface and reducing the height of the abrasive grains protruding from the binding agent. Plasma experiments were carried out via LTDBDGW. When the laser was vertically incident, and the laser power density was 3.359 × 10⁸ W cm⁻², the Boltzmann plot method and the Stark broadening method were used to get the plasma electron temperature and the plasma electron density, which were approximately 9700 K and 1.6128 × 10¹⁶ to 2.0636 × 10¹⁶ cm⁻², respectively. LTDBDGW experiments were conducted with and without assisted blowing. Surface quality improvement of the grinding wheel was confirmed with auxiliary blowing.