Runout rejection in end milling through two-dimensional repetitive force control

Abstract

Cutter runout presents an impediment to the attainable productivity and part quality in machining processes. This study establishes a mechatronic approach to compensate for cutter runout effect during multi-flute machining in real-time. It is accomplished through measuring the runout-related cutting force component, formulating repetitive controlling commands, and manipulating the workpiece position to counteract the variation of chip load during the course of machining. In an end milling configuration, the approach has been realized with a two-axis test bed attached to the machining table. The test bed operates independently to the computer numerical control (CNC) servo loops of the machine tool, and it provides a fine range and high frequency motion of the workpiece. In this paper the development of the test bed is discussed in terms of the hardware component design and the software controller formulation. Numerical simulation of the cutting force in response to repetitive learning control at the presence of runout disturbance is examined. To evaluate the feed-back system performance, experimental study based on the implementation of both single- and two-dimensional controls is presented in the context of cutting force regulation and part surface finish improvement.