Interaction mechanism and load model between disc blade and coal rock under axial vibration cutting

Aiming at the problems of high loss， low efficiency and easy wear of existing cutting tools by cutting coal rock under complex geological conditions (especially hard rock)， a method of cutting broken coal rock under compos⁃ ite vibration of disc cutter with truncation⁃wedge effect was proposed， and the compound cutting and crushing coal rock was realized by radial feed of disc cutter and different vibration forms and postures. The mechanical characteristics of broken coal rock under axial vibration cutting were studied based on the disc blade study. Based on the shear fracture theory， the failure condition of coal rock under blade load and the calculation method of the equivalent con⁃ centrated load when the blade axially vibrates downward， upward， and radially cuts coal rock were given. A theoreti⁃ cal model of the correlation between the blade structure parameters and the load was established by the method of dis⁃ placement strain⁃equal force synthesis， and the load characteristics of the crushed coal rock under the conditions of ra⁃ dial single⁃acting interception and axial vibration composite cutting were studied by numerical simulation. To study the load of disc cutter in crushing coal rock under the experimental conditions of vibration and vibration⁃free， the theoreti⁃ cal calculation and numerical simulation of blade load were compared with the experiment. The results show that the area of damage to coal rock by the disc blade gradually decreases from the middle to the two sides， which coincides with the numerical simulated stress cloud diagram， the radial load of blade in numerical simulation and experiment un⁃ der the vibration cutting condition are less than the load value under the vibration-free condition. The numerical simu⁃ lation and experimental loads show an obvious periodic fluctuation law with the axial vibration displacement under the axial vibration cutting， and which is an advanced phase difference， the amplitude of radial and axial load and the am⁃ plitude of vibration displacement are not simultaneous， and the phase difference decreases with the increase of vibra⁃ tion frequency. With the increase of cutting thickness， the theoretical value and simulation value of the radial load of the disc cutter coincide with the increasing change law of the experimental value， the mean error is 12.01% and 6. 37%， respectively. The errors between the theoretical， simulated and experimental values of the radial load (corre⁃ sponding to the mean load at the maximum amplitude) when the disc blade vibrates axially upwards are 11.65% and 13.99%， the errors of the axial load are 10.46% and 13.51%， respectively. When the axial downward vibration， the errors of the radial load are 13.91%， 5.61%， the errors of the axial load are 14.90% and 7.88%， respectively. Com⁃ bined with the load model of disc wedge surface in the existing literature， the correctness of the load model of disc blade was verified， and then the feasibility of establishing the load model of composite motion rock breaking by using the method of displacement strain⁃equal synthesis was explained.