Cylindricity control in precision centerless grinding
Abstract
A computer simulation method for investigating the form generation mechanism in the centerless grinding process is described. In this work, instantaneous change of the apparent depth of cut during grinding was modeled using absolute coordinate systems. The result of the simulation was not affected by the coordinate system (the location of the reference circle center and the radius of the reference circle). Also, analytical models of the interference phenomena at the contact points were developed to investigate their effects on the roundness profile of a centerless ground workpiece. In order to study the effects of grinding variables on grinding mechanism, details of the machining factor were formulated using such process variables as grinding wheel speed, wheel specification, regulating wheel speed, dressing condition, etc. A least squares contact line was formulated to include the effect of workpiece orientation relative to the grinding machine. Using these formulas, 2-D, 3-D infeed, and 3-D through-feed centerless grinding simulation models were developed. For the 3-D through-feed simulation model, grinding forces of previous and/or following workpieces were assumed as a function of the current workpiece location. The experiments and computer simulations were carried out using three types of cylindrical workpiece shapes with varying flat length. To validate these models, simulation results were compared with the experimental results. It was found that the number of lobes and the angular displacement of peaks and corresponding valleys of the simulation results were identical with those of the roundness profiles of ground workpieces. Through 2-D simulation, it was verified that grinding wheel interference is affected not only by geometry but also by machine elasticity. 3-D simulation results revealed that the effect of flat end is propagated to the opposite end through workpiece reorientation. It was shown that the inherent tapering error of the through-feed centerless grinding exists. The effects of the center height angle $(\beta),$ the number of workpiece rotations, the regulating wheel tilt angle $(\varphi),$ and the slope of the grinding wheel inlet crown on the geometric tolerance of a cylindrically centerless ground workpiece were investigated.
Degree
Ph.D.
Advisors
Barash, Purdue University.
Subject Area
Industrial engineering|Mechanical engineering
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