Dominant Cutting Parameters Affecting the Specific Energy of Selected Sandstones when Using Conical Picks and the Development of Empirical Prediction Models

• Published in: Rock mechanics and rock engineering 2018-10, Vol.51 (10), p.3111-3128
• Main Authors: Wang, Xiang, Wang, Qing-Feng, Liang, Yun-Pei, Su, Okan, Yang, Lin
• Format: Article
• Language: English
• Subjects: Civil Engineering; Compressive strength; Cutting; Cutting equipment; Cutting force; Cutting parameters; Depth; Dredging; Earth and Environmental Science; Earth Sciences; Empirical analysis; Energy; Energy measurement; Excavation; Geophysics/Geodesy; Machine tools; Mathematical models; Original Paper; Parameters; Prediction models; Process parameters; Rake angle; Regression analysis; Rocks; Sandstone; Solutions; Specific energy; Statistical analysis; Statistical methods; Statistics; Tests
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-018-1522-1

Specific energy is one of the most significant parameters in the process of rock cutting and it has been widely used for evaluating the performance of excavation machines. In this paper, based on rock cutting tests that were conducted on a linear cutting machine (LCM), the effects of relevant cutting parameters and characteristics, including the clearance angle, the cone (tip) angle of conical picks, the rake angle and the cutting depth on specific energy were investigated. Five different conical picks with the cone angles between 60° and 100° were used in the experiments. In addition, five different sandstones with uniaxial compressive strength varying from 17.91 to 85.98 MPa were subjected to cutting tests under different levels of cutting parameters. As a result of the tests, it was found that the clearance angle has a considerable effect on cutting force and specific energy. When it was greater than 10°, mean cutting force increased with the increasing cone angle, yet linearly decreased with the increasing rake angle and attack angle. However, specific energy has no statistical relationship with the attack angle, the rake angle, and the cone angle. It does not vary effectively with the relevant angles. Statistical analyses also indicate that strong relationships exist between the specific energy and the cutting depth in a power function. In this context, a general model of specific energy was proposed, and based on the test data and previous studies, empirical models of specific energy were developed using multiple non-linear regression and principal component regression methods. Besides, the statistical analyses showed a good agreement between the measured and predicted specific energy in unrelieved and relieved cutting modes. In conclusion, some prediction models of roadheader production rates were developed that were based on the models of specific energy. By comparing the results with the literature, it was found that the proposed models are valid in predicting the instantaneous cutting rate of roadheader especially at the cutting depth of 7–9 mm. They can be used for preliminary estimation of the production rate of roadheaders. Thus, it can be claimed that the models can offer effective solutions for the prediction of production rate of roadheaders equipped with conical picks.