Monitoring of Machining Processes Using Sensor Equipped Tools

Abstract

A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By this way, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350 °C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set‐up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains.

Bismuth-Based Perovskite Derivates with Thermal Voltage Exceeding 40 mV/K

“…Unfortunately, the low solubility of the bismuth precursors prevented control of the doping degree. Besides, it has been reported that ionic compensation of point defects could impact doping efficiency. , On the other hand, the 40 mV K –1 thermal voltage produced by MABiI and S.MABiI can be exploited in thermoelectronics. ,− Bi-based perovskite derivates are also easily processable, scalable, and cost-effective, and if MABiI and S.MABiI were employed in thermoelectronics, they could allow the device to scale down from millimeters to microns and deliver a thermal voltage higher than that reported in conventional devices. − Besides, low-dimensional perovskite derivates are increasingly attracting the interest of applied research, thanks to the possibility of exploiting the phenomena resulting from charge confinement in bulk materials.…”

Experimental Investigation of Hard Turning Mechanisms by PCBN Tooling Embedded Micro Thin Film Thermocouples

“…Embedded micro TFTC sensors due to their micro-size dimensions offer a very high temporal and high spatial resolution and the ability to simultaneously record, in real-time, temperatures at and near the cutting zone [9][10][11][12][13][14][15]. The spatial-and/or temporal-resolution of TFTC sensor arrays depends on junction size and the relative distance between sensing junctions.…”