Adaptive Control System for Optimizing the ECG Process under the Overcut Constraint
One of the main limitations 1n Peripheral Electro Chemical Grinding (ECG) is the overcut phenomenon. The dominant parameters which govern the dimensions of the geometrical overcut are the voltage and the feedrate. This paper deals with the development of an empirical model which describes the overcut as a function of the dominant parameters. Pased on this model an adpative control system was built and experiments in Profile Peripheral ECG were carried out. A comparison of the results obtained with and without the adaptive control system is presented as well as the relationship between the side and bottom overcuts. According to the above an adaptive strategy to control the geometrical overcut in Profile ECG is suggested.
Off-line multiresponse optimization of electrochemical surface grinding by a multi-objective programming method
Abstract The objective of this study is to optimize electrochemical grinding (ECG) process responses simultaneously by an off-line multiresponse optimization methodology. The responses considered as objectives are side and bottom overcuts, surface finish, spindle load, total metal removal rate, and wheel wear. Materials of 304 Stainless Steel are ground by the ECG process. The process variables optimized for the above objectives include electrolyte type, wheel material, grit size, grit concentration, d.c. voltage, electrolyte flow rate, wheel speed, feed rate, and ripple effect. A simple weighting method transforms the multi-objective problem into a single-objective programming format and then, by parametric variation of the weights, the set of non-dominated optimum solutions are obtained. It is shown in this paper that the multi-objective optimization methodology can be applied for an ECG operation, and that the optimal operating conditions for any given set of weights can be obtained depending upon the objectives.
Phase diagram and magnetic properties of the diluted fcc system NipMg1-pO.
Starting from Ni and Mg nitrates, about 20 samples of ${\mathrm{Ni}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O samples (with 0.06\ensuremath{\le}p\ensuremath{\le}0.86) were prepared and x-ray-diffraction studies showed the samples to have the NaCl structure with the lattice constant fitting the expression a(p)=4.2115-0.0340p \AA{}. Temperature-dependent magnetic-susceptibility (\ensuremath{\chi}) studies of the samples were carried out between 1.8 and 600 K using a superconducting-quantum-interference-device magnetometer and N\'eel temperatures ${\mathit{T}}_{\mathit{N}}$'s were determined from the peak in \ensuremath{\partial}(\ensuremath{\chi}T)/\ensuremath{\partial}T. The variation of t=${\mathit{T}}_{\mathit{N}}$(p)/${\mathit{T}}_{\mathit{N}}$(1) vs p is compared with that of ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O. For both systems, the variations for pg0.31 are found to fit the predicted values for a simple-cubic Heisenberg antiferromagnet and a theoretical basis for this anomalous result is advanced. The experimental percolation threshold ${\mathit{p}}_{\mathit{c}}$=0.15\ifmmode\pm\else\textpm\fi{}0.01 and for ${\mathit{p}}_{\mathit{c}}$p0.31, \ensuremath{\chi} below ${\mathit{T}}_{\mathit{N}}$ shows irreversible behavior for the zero-field-cooled and field-cooled cases, suggestive of spin-glass-like behavior also observed in other diluted fcc antiferromagnets, such as ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O and ${\mathrm{Eu}}_{\mathit{p}}$${\mathrm{Sr}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$Te. It is suggested that the differences in the t-vs-p variations for p0.31 in ${\mathrm{Ni}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O, ${\mathrm{Co}}_{\mathit{p}}$${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$O, and ${\mathrm{Eu}}_{\mathit{p}}$${\mathrm{Sr}}_{1\mathrm{\ensuremath{-}}\mathit{p}}$Te may be related to the differences in the ratio of the next-nearest-neighbor to nearest-neighbor exchange constants in these systems.