Influência das condições de usinagem do brunimento flexível na rugosidade de cilindros de blocos de compressores herméticos

Abstract

The purpose of this work is to evaluate, using a complete factorial design, the effect of machining conditions (speed, feed rate and tool strokes numbers) used during the flexible honing process in roughness (Ra, Rq, Rp, Rv, Rt, CV, Rk, Rpk, Rvk, Vo, Rsk e Rku) of the hermetic compressors blocks cylinder. The conventional honing was done by EMBRACO, while the flexible honing was conducted at Federal University of Uberlândia using a CNC machining center and a flexible honing which consists of a metal rod and nylon bristles with abrasive lobes at the tips. The roughness measurement was conducted by an electromechanical rugosimeter. For each measuring was estimated its respective measurement uncertainty, using the method proposed in the GUM, except for Rsk and Rku parameters that was used the Monte Carlo method. The results indicated that the flexible honing process using three strokes of the tool, speed 700 rpm and feed rate of 1400 mm/min provided the best surface finish considering the functionality of the cylinders. The flexible honing reduced height of the peaks and eliminated isolated peaks without changing the depth of the valleys, which can lead to improvements in softening properties of the surface, lubricant retention, mechanical strength and capacity to withstand loads in contact operations.