A Comprehensive Model for Dynamic Force Prediction in Peripheral Milling Including the Effects of Flank Face Interference
 
 
 

Santosh K. Ranganath | PhD | 1999

End milling is one of the most versatile and commonly used machining processes and finds wide applications in automotive, aerospace, and tool and die industries. The focus of the present research is on the development of a comprehensive model for the dynamic force behavior in the peripheral milling process. This model not only looks at the cutting process but also considers the ploughing and flank face interference mechanisms occurring along the clearance/flank face of the tool. This interference causes certain forces to be produced that are computed from the actual volume of interference occurring at any instant of time. This volume is obtained using the cutter geometry (runout, trochoidal tool path) and cutter dynamics (cutting conditions, tool deflections) information.
The cutter dynamics, especially for long cutters, have a major impact on the interference forces. The high cutter deflections and tool indentation speeds especially for long cutters significantly affect the rate at which interference forces change over time. This velocity dependence considerably affects the model predictions. The tool indentation velocities also influence the instantaneous tool clearance angle values, which in turn affects the formation of the interference volume and the magnitude of the interference forces. Therefore, the tool clearance angle changes are used in computing the rate of change of the interference forces. Since this rate component is in phase with the deflection speeds, its behavior is analogous to a viscous damping or cutting process damping effect in the system.
 

The enhanced force model predictions with the interference and rate of change effects are validated by experiments performed on a range of cutters and cutting conditions. Specific sliding indenter tests are performed to calibrate the frictional interference coefficient. Also, a new approach to obtain the specific ploughing coefficient using the theory of contact mechanics is also developed and verified. Cutter irregularities such as runout due to tilts, offset, and grind are estimated using an enhanced runout model and a non-linear optimization strategy. The effects on the forced vibrations and stability characteristics of the system especially in the low to medium speed ranges are also investigated, as an application of the new model.

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