Development of a novel variable rake angle mechanism for noncircular turning and its control

A prototype tool stage with a variable rake angle mechanism has been developed and controlled. The objective of the variable rake angle mechanism is to provide two-degrees-of-freedom to the conventional noncircular turning process, so that the rotational tool mechanism can compensate for the rake angle change caused by the noncircular cam profile itself while the translational tool motion generates the cam profile. Inverse kinematics, kinematic sensitivity and stiffness, and design of the variable rake angle mechanism are discussed. Robust repetitive controllers are designed for two actuators in the variable rake angle mechanism. Two actuators operate together to change the tool position as well as the tool angle. Experimental results on the variable rake angle mechanism support the design concept and control approach.