The intention is to develop a modular, sensor-based monitoring system for the grinding action, combining intelligent diagnosis of the dressing/conditioning and grinding processes with automatic process optimization (grinding and dressing).
The accuracy, stiffness and other relevant parameters of an existing grinding machine for conventional grinding wheels were adapted to cubic boron nitride (CBN) grinding requirements, greatly improving the machine. In addition, a modular system for process monitoring, diameter measurement, concentricity measurement and roughness measurement was developed and was integrated successfully in the above mentioned machine; the development work was accompanied by an extensive series of measuring and experimental tests.
Analysis of the process by the measuring and monitoring modules is based on sensor information acquired by each module. An extensive sensor system was therefore installed in the machine, in order to establish the type of sensor which provides the most informative data on the relevant process states. This includes the derivation of informative parameters from the sensor signals. Sensor types installed on the machine included piezoelectric force sensors in the form of single force cells, force measuring plates and force measuring rings, together with inductive displacement sensors for distance and force measurement and with acoustic emission (AE) sensors, optical sensors and effective power sensors.
As a result of the project, the functions of the various sensor types were improved, yielding positive benefits for other applications of this sensor technology outside the grinding machine sector, for example on lathes, milling machines or drilling machines.
An ultrahigh precision contactless diameter and concentricity measuring module and a contactless roughness measuring module were developed. Following implementation of test results in a monitoring module, it is now possible to monitor the grinding, dressing and sharpening processes for unacceptable errors; the measuring and monitoring modules are interlinked with the machine control so that the grinding machine can respond automatically to alarms.
The ability of the individual sensor components to function in the machine space under process conditions will be demonstrated by applying the system to a cylindrical grinding machine of one of the partners, which is capable of producing cylindrical parts with a maximum diameter of dw=200 mm and a maximum length of 1w=500 mm.
A realistic production test of the innovative sensors and evaluation of the monitoring strategies can be achieved only through a series of representatives tests with all the sensors acting together within the machine cycles.
The optical surface analysis system, the structure-borne sound sensors used to monitor grinding wheel dressing and tool life and the non-tactile diameter measuring system will therefore all be fully integrated in the machine. Extensive machine modifications will be necessary for this purpose.