Micropositioning in the Turning Process Via Magnetostrictive Actuation
 
 

Krishna Vinod Domala | MS | 1995

Quality of manufactured products has a role in determining the performance of a product. Surface quality is an important functional feature of a product when the product's applications involve properties such as reflectivity, conductivity and tribological properties. In order to produce parts that have desirable surface properties, it is necessary to undersatnd the evolution of these quality characteristics through surface generation mechanisms involved in the manufacturing operations.

Grinding is a widely used machining operation that accounts for about 20-25% of the machining costs of an industrialized nation. The focus of this research therefore, is on developing analytical model for the surfaces resulting from a grinding process. An important factor that determines the final workpiece geometry is the geometry of the wheel surface. Therefore, a model for wheel surface is also developed, since such a model is critical for understanding the surface generation mechanism in grinding. A knowledge of these surfaces in three dimensions is required for the ability to control the surfaces resulting from this process. Accordingly, characterization and simulations in three dimensions are performed in this research.

First, a model for the surface texture generated by a surface grinding process is developed based on the kinematics of the process. The model is verified through grinding experiments, and simulations performed with the model are used to understand the effect of cutting conditions on the texture of the workpiece. Based on geometric conditions alone, it is shown that for achieving higher production levels with the same finish requirements, the wheel speed and the feed rate have to be increased by the same factor.

Spectral analysis is used to characterize a ground surface in three dimensions. The fault diagnostic capability of this technique is then illustrated by identifying defects from the spectrum of a ground workpiece. It will be shown that defects such as machine tool vibration and spindle runout or using an out-of-roundness, can be identified from the Fourier spectrum of surfaces.

Next, a model for the wheel surface is developed using the inverse Fourier transform. The Fourier spectrum of a wheel is decomposed and parameters characterizing the surface are identified. These parameters are later used in simulating a wheel surface. The developed methodology involves manipulating the characteristics of a basic structure that composes the Fourier spectrum. The model is verified and then integrated with the process model. The utility of these models is illustrated through simulations performed with the integrated model. Simulations indicate that low frequency components occuring in the wheel due to clustering of abrasive grains result in higher workpiece roughness, and hence should be avoided.

If you have any comments or suggestions please e-mail jwsuther@mtu.edu.