DESIGN AND PERFORMANCE PREDICTION MODELING OF A PERCUSSIVE ROCK DRILLING DEVICE

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DTH ????????? ????????????????????? ???????????? ????????? ????????? ????????? ??? ?????? ?????? ????????? ??? ????????? ??????????????? ??????????????? ???????????? ????????? ???????????????. ????????? ?????????????????? ??????????????? ??????????????? ????????????????????? ???????????? ????????? ????????? ????????? ??? ?????? ????????? ???????????? ?????? ????????? ?????????. ?????? ???????????? ?????? ????????? ?????????????????? ???????????? ??????????????? ????????????. 2???????????? ????????? ????????? ??????????????? ????????? ????????? ????????????????????? ????????? ??????????????? ????????? ??? ?????? ??????????????? ????????? ????????????. ??????, ????????? ????????? ?????? ????????? ??????????????? ???????????????. ???????????? ???????????? ????????? ?????? ????????? ?????? ????????? ?????? ???????????? ??? ?????? ????????? ???????????? ???????????? ??????????????? ???????????? ????????? ???????????? ????????? ???????????????. ??????, ????????? ????????? ?????? ??????????????? ???????????? ?????? ?????? ??? ????????? ????????? ???????????????. ??? ??? ???????????? ?????? ??????????????? ???????????? ???????????? ??????????????? ????????? ???, ????????? ?????? ???????????????. ???????????? ?????????, ??????????????? ?????? ????????? ????????????????????? ????????? ????????? ????????? ??? ?????? ??????????????? ????????? ???????????????. 3 ???????????? ??????????????? ?????? ??????????????? ????????? ???????????? ?????? ???????????? ?????? ????????????. ??????, ????????? ??????????????? ??????????????? ????????? ?????? ?????????????????? ???????????? ????????? ????????? ?????? ??????????????? ???????????????. ?????? ????????? ??????????????? ?????? ??????????????? ?????? ????????? ??????????????? ???????????????. ??????????????? ?????????, ??????????????? ????????? ?????? ?????? ???????????? ?????? ????????????. ?????? ??????????????? ??????????????? ????????? ??????????????? ?????????????????? ????????????????????? ?????????????????? ???????????? ??????????????? ??????????????? ???????????? ??????????????? ???????????? ???????????? ????????? ????????? ?????????. ???????????????, ??????????????? ???????????? ??? ?????? ????????? ???????????? ????????? ????????? ????????? ??????????????? ???????????????. 4 ???????????? DTH ????????? ?????? ??????????????? ???????????? ??????????????? ????????? ????????????. ?????? ?????? ??????, ?????? ??????, ????????? ??? ????????? ???????????? ?????? ????????? ????????? ??????????????? ?????? ????????? ???????????? DTH ????????? ?????? ?????? ????????? ???????????????. ????????????, DTH ????????? ??????????????? ???????????? ????????? ?????? ?????? ??? ?????? ????????? ????????????, ??????????????? ??? DTH ????????? ???????????? ????????? ???????????? ?????? ?????? ?????????. ??????????????? DTH ????????? ?????? ????????? ????????? ?????? ????????? ??????????????? ????????? ???????????????. 5???????????? ????????? ?????????????????? ??????????????? ???????????? ?????? ???????????? ?????? ????????? ????????? ????????????. ?????? ?????? 2????????? ????????? ???????????? ????????????, 3????????? ????????? ????????? ????????????, ??? 4?????? DTH ?????? ???????????? ????????? ???????????? ???????????? ??????????????? ???????????????. ??? ????????? ?????? ??????????????? 2????????? ????????????. ??? ?????? ????????? ???????????? (???, DTH ??????, Top ??????)??? ???????????? (????????????, ????????????)??? ?????? ????????? ???????????? ????????? ????????????, ????????? ????????? ????????? ??? ?????? ?????????????????? ???????????????. ??? ??????, ?????? ?????? ?????????????????? ????????? ????????? ??? ?????? ??????????????? ????????? ???????????? ??????????????? ??????????????? ???????????????.This study analyses major design parameters of the drill-bit and down-the-hole (DTH) hammer that are the core parts of percussive rock drilling devices and explores a design methodology that can ensure optimal performance. First, this study analyses major design parameters for the drill-bit and impact equipment of a rock drilling device, and then discusses the optimal design value from which optimal performance can be expected. In addition, it researches a drilling performance prediction model based on numerical analysis for percussive rock drilling devices. In chapter 2, the aims to determine the optimal design parameters for percussive rock drilling devices considering the bit-rock interaction. First, the dynamics of a drill-bit impacted by a dropped piston are modeled by impact stress propagation and a rock breaking mechanism representing the penetration resistance coefficient and unloading constant. Next, the damping vibration behavior of the bit is investigated considering the impact duration and the rock loading/unloading conditions. Finally, the drilling efficiency, defined by the energy transmitted from the piston to the rock, is presented in terms of the proposed parameters. The use of optimal design parameters for percussive drilling systems improved the drilling efficiency. In chapter 3, major design parameters of the dill-bit are identified and verified. First, a piston-drop testing system is created to analyze the hitting impact of the button, and the hitting test on granite rock is performed. Based on the result of the single-button hitting test, the rock-crushing performance according to the button arrangement is determined. Second, this chapter was focused on the optimum design of the internal flushing channel of a drill-bit. In chapter 3, designed an appropriate experiment to assess the physical dimensions and the operating characteristics of internal flushing channel. Then, multi-phase CFD simulations and response surface methodology (RSM) was used to optimize the flushing capacity by analyzing the relationship between the selected design parameters and the results of the simulation. Finally, focuses on validating the effect of the drill-bit button arrangement and the design of internal flushing channel on the drilling performance. Chapter 4 presents the simulation model to predict the percussive rock drilling performance of the down-the-hole (DTH) hammer. First, the dynamic model of the hammer is developed in the consideration of mass flow relations representing orifice opening areas of the air tube, the piston and the bit flushing channel. Next, the performance of hammer was evaluated via numerical simulation model through fluctuation of front and rear chamber pressure, impact frequency and impact power which is representative performance of hammer. Also, the simulation model is proved through a series of the laboratory tests. Finally, an optimum set of design factors for increasing the drilling efficiency of the hammer system was proposed. Chapter 5 describes a platform based on numerical analysis for predicting the drilling performance of a percussive drilling system. For such a purpose, a drilling performance prediction model developed in connection with the drill-bit movement model suggested in chapter 2, the button-hitting effect suggested in chapter 3, and the DTH hammer simulation model in chapter 4, is proposed. This study makes two suggestions. First, key design parameters for core parts (e.g. drill-bit, bit-rock interaction, hammer system, and impact equipment) of the percussive rock drilling system (i.e. DTH hammer, top hammer) are defined, and a design methodology that enables the optimal performance is proposed. Second, a drilling system performance prediction system based on simulations that can predict the performance of the drilling system based on the above-mentioned methodology is proposed. Such results will be useful as basic data for the performance evaluation of percussive rock drilling systems.Docto