Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
Thermal aspects of ceramic grinding
Abstract
The present research is part of an overall effort to explore the feasibility of grinding ceramics with large removal rates using high wheel speeds and fine grit wheels so as to maintain a small grit depth of cut and minimize workpiece damage. Grinding of ceramics with small grit depths of cut may require high specific energies which, in turn, should lead to high grinding zone temperatures. Temperatures generated in grinding could significantly affect the grinding mechanisms and resulting surface condition. It has been suggested that elevated grinding zone temperatures may inhibit fracture and promote a non-detrimental ductile mode of grinding. On the other hand, excess heating could drastically reduce the useful life of a grinding wheel. In order to calculate the temperatures generated by grinding, it is necessary to know the fraction of the total energy conducted as heat to the workpiece. In the present research work, an inverse heat transfer method is used to estimate the energy input to the workpiece from measured temperatures in the subsurface. This energy is then compared with the total measured energy input, obtained from the measured grinding force and power, to determine the fraction of the grinding energy conducted as heat to the workpiece. Two types of measuring systems are used to measure the subsurface temperatures in the workpiece. The first system utilizes a thermocouple embedded in the workpiece. The second utilizes a two-color infrared detector and optical fiber. With both systems, the temperature is measured at the bottom of a blind hole drilled from the underside of the workpiece. An important drawback with the embedded thermocouple is its slow response and poor contact between the workpiece and thermocouple tip, thus the peak grinding zone temperature can not be accurately measured. The two-color detector system provides a faster response and more accurate results. An important feature with the two-color system is that the emissivity of the target surface is not required for the measurement. It is found that the energy partition to the workpiece is about 12 to 20% for wet grinding and 45% for dry grinding. The grinding fluid plays an important role in the energy partition for ceramic grinding. It is proposed that the main role of the fluid is to prevent the buildup of workpiece material on the wheel, which provides a thermal barrier on the diamond abrasive tips. A thermal analysis indicates that the hole drilled in the workpiece disturbs the original temperature field, such that the measured temperature at the bottom of the hole overestimates the actual subsurface temperature in the workpiece.
Subject Area
Mechanical engineering
Recommended Citation
Zhu, Jonathan Bo, "Thermal aspects of ceramic grinding" (1996). Doctoral Dissertations Available from Proquest. AAI9639058.
https://scholarworks.umass.edu/dissertations/AAI9639058