Microscopic Wear Characteristics of Ceramic Grinding Wheel in Creep Feed Grinding

This paper deals with the microscopic wear characteristics of ceramic (Seeded Gel, SG) grinding wheels used in creep feed grinding. Creep feed grinding experiments with SG grinding wheels were carried out compared to rose-pink alumina (RA) grinding wheels. To clear the wear characteristics of the wheel working surface in creep feed grinding, changes in the shapes of grain cutting edges were observed by a field emission-scanning electron microscope (FE-SEM). This is a self-sharpening phenomenon based on micro fractures generated on the top of SG grain cutting edges. On the other hand, large fracture and attritious wear effected RA grain cutting edges. In addition, the features of any grain cutting edges were evaluated using attritious wear flat percentage. Changes in attritious wear flat percentage of SG grits maintained constant value and were stable. From these results, the influence of wear mode of the grinding wheel on grinding characteristics parameter, such as grinding force and workpiece surface roughness, is understood.

AN INVERSE OPTIMIZATION PROBLEM OF HEAT TRANSFER IN THE MACHINING PROCESS – A REVIEW

This paper reports on the results of research on thermal aspects in the process of material removal by inverse heat transfer problem. The research focuses on the identification, modeling and optimization of machining process based on the measured temperature at a particular point of the workpiece. The inverse approach determines the overall temperature distribution of the workpiece and the unknown heat flux at the tool/workpiece interface in machining. By introducing and minimizing an objective function based on the heat flux function, relationship of the heating power and duration on the surface layer of the workpiece is optimized. In this way, the most favourable machining conditions are determined in order to achieve high productivity and quality levels. The inverse optimization problem is solved by using the analytical, numerical and regularization methods. Formulation, application and analysis of the inverse optimization problem of heat transfer are shown on the example of creep-feed grinding. The creep-feed grinding process is a widely used abrasive machining process that is characterized by high thermal load of the workpiece. The results of the inverse optimization problem were verified by a series of experiments under different machining conditions.