Issue 42

J.-f. He et alii, Frattura ed Integrità Strutturale, 42 (2017) 263-271; DOI: 10.3221/IGF-ESIS.42.28 268 the related experiments are conducted in order to improve the service life of hydraulic DTH hammers while in horizontal directional well drilling. In end, the abrasion rate of hydraulic hammer with horizontal oriented sliders is obtained, and the abrasion property of horizontal oriented sliders is discussed according to numerical simulation results. Meshes No. 42318 Friction Coefficient 0.02 Applied loads (kN) 1 Total Steps 1000 Time Step 2 Convergence Coefficient 0.5 Moving Velocity of Hammer (m/s) 3 Table 2 : Details of boundary condition and solver settings. Effects of hammer mass on abrasion property of hydraulic hammer with oriented sliders As shown in Fig. 5, the Von-Mises stress of oriented sliders has been obtained. While the mass of the anvil is 60kg, the main stress of oriented sliders is approximately 6MPa. It can be implied that the main stress of horizontal oriented sliders is nearly linearly increasing with the raise of anvil mass. While the mass of the anvil exceeds 100kg, the main stress of oriented sliders will exceed 9MPa, which will reduce the working performance of hydraulic hammer with horizontal oriented sliders. Thus the abrasion between horizontal oriented sliders and external cylinder has been increased while the applied stress of oriented sliders is increasing. Therefore, the mass of anvil should be less than 100kg while in horizontal directional well drilling with hydraulic hammer, which contributes to improvement and optimization on the design of hydraulic hammer with horizontal oriented sliders. Figure 5 : Effect of anvil mass on the Von-Mises stress of hydraulic hammer with horizontal oriented sliders. Meanwhile, the variation of anvil mass on the abrasion property of hydraulic hammer with horizontal oriented sliders is shown as Fig. 6. The lighter the impact hammer is, the abrasion rate of oriented sliders will be, and the service life of hydraulic hammer with horizontal oriented sliders will be longer. It can be concluded that the abrasion rate of oriented sliders is approximately exponentially increasing the augment of hammer mass. The maximum abrasion rate of horizontal oriented sliders is 7.5 ‱ , which meets the requirements of impact energy of hydraulic hammer while in horizontal