Análise da eficiência do processo de usinagem por hidroerosão sem renovação de partículas abrasivas

Abstract

The hydroerosive grinding cycle time increases after long-term use of erosive media without particle reload, thus characterizing the reduction of process efficiency. Modifications on solid and liquid phases contribute for this reduction. In this work the process efficiency indicators were obtained from a 150 hours production period without particle reload. The production consists of diesel injection nozzles inlet rounding by hydroerosive grinding. For this period the B4C particle size distribution, solid volume fraction, fluid viscosity and density were obtained. Particle shape factors were obtained by a computational routine using Matlab. After 150 hours the process efficiency was reduced by 20% and this reduction can be attributed to 28% decrease of solid volume fraction, to fine particles increase and to the 50% reduction in fluid viscosity. The hydrodynamic interactions between particles and fluid were characterized by the particle momentum equilibrium number. This parameter is used to classify the particle-fluid coupling, thus the impact efficiency. At the end of the monitored period the volume of particles classified as high coupling was reduced by approximately 30% and this represents negative impact for the process efficiency. The efficiency loss did not exceed 5% for the first 70 hour of production, and then this value could be used as reference for the maximum run period without particle reload.