Tool design for the integration of piezoelectric and micro magnetic sensors to realize in-process measurements in BTA deep hole drilling

Abstract

In-process measurements are often used to gain information and increase the understanding of the machining process. Furthermore, these measurements can be used to control the process during machining. In processes such as milling or turning the sensors and measuring devices can often be placed inside the working area of the machine or attached to the tool and observe the contact area between tool and workpiece. The contact area of processes such as drilling, boring or BTA (Boring and Trepanning Association) deep hole drilling is inaccessible from the outside. The BTA process is a deep hole drilling method used mainly for machining relatively large diameters in complex and cost-intensive parts often at the end of the value chain. The resulting bore surfaces of these parts are often highly stressed and are commonly subjected to post-processing. With sufcient information about the process and the produced surface integrity of the bore, this post-processing could be reduced or even omitted. In order to get information about the contact area or the resulting surface of the bore, without destroying the workpiece, sensors need to be implemented into the tool in order to measure from inside the bore. The challenges in the design process of the drill head modifcations and the implementation of two diferent sensor systems are discussed in this paper. Furthermore, the manufacturing and application of the modified BTA drill heads are described. Finally, the results from cutting tests on one of the modified drill heads are presented.