3D laser investigation on micron-scale grain protrusion topography of truncated diamond grinding wheel for precision grinding performance

摘要

A grain tip (GT) truncation is proposed to truncate grain protrusion tips of #270 diamond grinding wheel in plunge grinding of hard and brittle material. In this study, a 3D laser microscopy was employed to measure the wheel working surface and parameterize its 3D grain protrusion topography. The objective is to investigate how micron-scale grain protrusion parameters influence grinding performance such as grinding force and surface roughness. First, the GT truncation was performed after dressing of diamond grinding wheel in grinding experiment of quartz glass; then its 3D grain protrusion topography was constructed by smoothing 3D measured noise, matching measured point cloud, transferring protrusion frame and extracting 3D diamond grains; finally, the grain protrusion parameters such as grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle, grain clearance angle, etc. were investigated in connection with ground surface and grinding force. It is shown that GT truncation averagely decreases grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle and grain clearance angle by about 44%, 74%, 75%, 24% and 70% on whole wheel surface, respectively. However, it greatly increases active grain number by about 32 times and active grain volume by about 181 times in actual grinding with the depth of cut in 1 μm, thus leading to a decrease (about 80%) in surface roughness and an increase (about 40 times) in grinding force. It is also found that truncated diamond grain tips are mostly shaped with nanometer-scale tip wedges along grain cutting direction, leading to about 75% very large negative grain rake angles and about 75% large grain clearance angles, thus contributing to ductile-mode grinding. It is confirmed that the active grain number and active grain volume for the actual depth of cut may be regarded as main grain protrusion parameters to evaluate and predict the precision grinding performance of a coarser diamond grinding wheel.