Cutting force monitoring and control system for CNC lathe machines

The importance of cutting forces during turning processes creates the need for a simple and low-cost solution to measure those forces. Various improvements on the cutting performance can be achieved by using these measurements. The present study explains the design and construction of a cutting force sensor, as well as the implementation of a fuzzy logic controller to obtain a complete system to monitor and control the cutting forces in rough turning operations. The force sensor uses four strain gauges attached on the sides of the tool holder to estimate the cutting forces. The force controller is designed to smoothly adjust the feed rate because a fast change in the feed rate could damage the cutting tool. The maximum cutting force needs to be input manually in this approach, because it will be the reference variable for the fuzzy controller. The maximum force is selected by the operator based on tool conditions, tool temperature, machining conditions, workpiece material, tool material, etc. A balance between the speed required to achieve the reference force and the smooth feed rate change is considered. The simulation results obtained by controlling the cutting force along with the associated machining time improvements are presented in this paper.