Issue 27

G. Kuidong et alii, Frattura ed Integrità Strutturale, 27 (2014) 43-52; DOI: 10.3221/IGF-ESIS.27.06 43 A theoretical model for predicting the Peak Cutting Force of conical picks Gao Kuidong, Du Changlong, Jiang Hongxiang, Liu Songyong School of Mechanical and Electrical Engineering, China University of Mining & Technology, Xuzhou 221116, China luck_honey@163.com A BSTRACT . In order to predict the PCF (Peak Cutting Force) of conical pick in rock cutting process, a theoretical model is established based on elastic fracture mechanics theory. The vertical fracture model of rock cutting fragment is also established based on the maximum tensile criterion. The relation between vertical fracture angle and associated parameters (cutting parameter  and ratio B of rock compressive strength to tensile strength) is obtained by numerical analysis method and polynomial regression method, and the correctness of rock vertical fracture model is verified through experiments. Linear regression coefficient between the PCF of prediction and experiments is 0.81, and significance level less than 0.05 shows that the model for predicting the PCF is correct and reliable. A comparative analysis between the PCF obtained from this model and Evans model reveals that the result of this prediction model is more reliable and accurate. The results of this work could provide some guidance for studying the rock cutting theory of conical pick and designing the cutting mechanism. K EYWORDS . Conical pick; Peak Cutting Force; Fracture angle. I NTRODUCTION n tunneling and mining, interaction between cutting mechanism (shearer drum and cutting head) and rock realizes rock fragmentation. Cutting ability, crushing effect and production efficiency of cutting mechanism, determine the working performance of tunneling and mining equipment. However, the PCF prediction of conical pick plays an important role in the design of cutting mechanism. A considerable amount of research has been conducted on the PCF prediction base on theoretical, experimental and numerical method. The first PCF prediction model of conical pick was established by Evans based on the maximal tension stress theory [1], and Roxborough & Liu [2] and Goktan [3] appropriately modified the Evans mathematical model. According to experiment data from various rock cutting by conical pick, regression expressions between cutting force and rock compressive strength, tensile strength, dynamic and static modulus of elasticity, brittle index were established by Bilgin [4-5]. Tiryaki [6] adopted multiple linear and non-linear regression, regression tree model and neural networks method to predict the PCF of conical pick. Numerical method [7-9] is also applied to predict the PCF of conical pick. Viewing the references mentioned above, we find that: Compared with experimental date, the result calculated by current theoretical model exists a notable divergence; For the limitation of experimental date, application of empirical models is limited to a specific scope; Experimental method and numerical simulation method can obtain proper cutting force, but some disadvantages exist such as high cost and low efficiency. For these reasons, the vertical fracture mechanics model of rock cutting fragment is established based on the maximum tensile criterion and rock cutting theory in this paper firstly; then, the theoretical model for predicting the PCF of conical pick is I