| Nowadays, pipe roof method is widely used in forepoling methods when tunnels are excavated in areas of week or difficult ground. But there is no special facility provided presently at home. In most tunnels, substitute equipment is used, which is insecurity and inefficient. Yet the facility imported is very expensive. Against this background, this paper has begun the study on Forpoling Rig.Based on certain mechanical quality of the rock, the analysis on the Polycrystalline Diamond Compacts (PDC) bit and the rotary percussive drilling is carried out. After analyzing the fragmentation mechanism of rock in rotary percussive drilling, the designing of drill power pack of forepoling rig is studied. According to the analysis of self-excitated vibration that produced by the dry friction between the drill bit of pipe roofing and terrane, a vibration mathematical model of Bottom Hole Assembly (BHA) has been constructed, and its dynamic characteristic is analyzed. The BHA transmits its torsional vibration to the gear system of drill power pack and brings about nonlinear vibration. Based on the nonlinear exterior excitation, a nonlinear dynamic mathematical model on the gear system of drill power pack is established, and the simulation of its dynamic characteristic is launched. Because of nonlinear factors in hydraulic system, a dynamic nonlinear mathematical model on the hydraulic driving system of drill power pack is established by using power bond graph, and its dynamic characteristic has been researched through simulation and experiment. The experiment test shows that the experimental result and simulation result are basically identical, and the experiment achieves the anticipated purpose.The synthetical study presented above established a self-contained research system on the dynamic characteristics of drill power pack in this paper, which is provided with some theoretic significance and practical engineering-oriented value. |
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