Investigating the reduction of cutting resistance of granite specimen induced by microwave irradiation with varying irradiation times
Research output: Thesis › Master's Thesis
The thesis that describes researches made with high power microwave irradiation as a promising solution in hard rock excavation. The solution consists of using microwave energy for reducing cutting resistance of granite. Additionally, the study shows dependencies of forces, wearing, energy consumption and particle size distribution on spacing between cuts, time of irradiation with microwaves and distance from the initial surface. Minerals of the granite have different dielectric properties. It leads to heating of some parts of the specimen, which causes its cracking. This fact has positive effects in cutting force reduction. In the study, the cutting force has been reduced by 22 % after 45 seconds microwave irradiation. This means, that specific energy consumption was also reduced; analysis shows reduction by 20-40 % (for different cutting conditions) for 45 seconds treated sample. However, 30 seconds exposure time did not show any positive effect on forces and specific energy consumption. The difference in wear rate with respect to microwave irradiation is not clearly visible. The dependency between particle size distribution and microwave irradiation is noticeable only for 45 seconds exposure time, the analysis shows the smaller volume of fine particles. The study included analysis of two positions of spacing between cuts, such as 8 mm and 12 mm. The analysis shows that with spacing 8 mm cutting forces smaller for around 13 % and wearing of the tool is slower. However, increasing of spacing to 12 mm positively effects on specific energy consumption and particle distribution. The results show reduction in specific energy consumption by 20 % and the material is less overgrinded for spacing 12 mm. Regression models describing dependences of mean and peak cutting forces on irradiation time, distance from the initial top surface of the sample and spacing were obtained. Force maps characterizing force distribution within the cut face were created. In total, microwave energy assistance for cutting of granite has shown good results in case of its treatment during 45 seconds. The further investigations to be carried out are suggested.
|Translated title of the contribution||Untersuchungen zur Verringerung des Schneidwiderstandes von Granit durch Mikrowellenbestrahlung mit variierenden Bestrahlungszeiten|
|Award date||7 Apr 2017|
|Publication status||Published - 2017|