Dynamic Characteristics Study Of Drill Jumbo Boom Under High Frequencyimpact

Drill jumbo is a modern drilling equipment which is mainly used in tunnel and underground engineering as well as mine exploitation. It can move expediently and support multiple rock drills simultaneously. It is precise in drilling position, has high working efficiency and provides good working environment.As the key executor of rock drilling, the drill jumbo boom needs to bear tensile compressive load, bending twisting load as well as high frequency impact load. Dynamic characteristics of the boom under such external excitation have direct influence on the overall performance of the equipment. Therefore, it is necessary to accurately understand the dynamic characteristics of drill jumbo boom and thus determine whether the structure can withstand the damage caused by the dynamic load. Recent research of drill jumbo boom in China has mainly been focused on its kinematics and dynamics with particular interests in the equipment’s movement control. Research on dynamic characteristic of the drill jumbo boom is relatively rare.Realizing shortages in the research of boom, this work conducted simulation analysis on rock-breaking process of the drill bit, dynamic response and fatigue lifetime of the boom under impact load condition. Major contributions of this paper are listed as below:1. Rock-breaking process of the drill bit was numerically simulated using LS-DYNA software. Variation curves of penetration depth, velocity and resultant force were obtained from the simulation. Influences of impacting energy and rotary speed on rock crushing were discussed. The quantitative value of the resultant force provides basis for dynamic characteristics analysis.2. A rigid-flexible hybrid virtual prototype of the boom with all three sections of telescopic arm flexible was constructed by jointly using both ANSYS and ADAMS, which laid a foundation for further dynamic characteristic simulations.3. Dynamic stresses of the telescopic arm in five working conditions were simulated using ADAMS. Stress-time curves and transient stress distribution cloud atlas of the telescopic arm were obtained. Maximum stress point of the telescopic arm was found and thus verified the dynamic strength of the arm and provided data to the calculation of fatigue strength that may follow this work.4. The resonance response of the telescopic arm was simulated using ADAMS. Response curves of separately placed testing points on the telescopic arm under different driving frequencies were generated. The results showed that the swing of telescopic arm was greatly influenced by its pose. Working condition four was the worst for vibration. And the connection between2nd and3rd arm was a weak position of the structure because of its poor stiffness. Statistical analysis of displacement response at the top end of the drill rod in time and frequency domains indicated that the maximum vibration displacement and worst smoothness both happened under working condition four.5. Simulations for smooth deployment process of the boom with rigid mode and rigid-flexible coupling mode were conducted respectively. Comparison of simulation results indicated that dynamic characteristics of the boom changed when flexible body was induced.6. Based on the simulation results, stress-time history at weak points on the telescopic arm was extracted. Fatigue lifetime of the boom was estimated using the stress spectra obtained by rain-flow counting method with MSC.fatigue.The purpose of this study is to solve some open problems in the research of drill jumbo boom and at the same time trying to provide a set of methods for studying boom dynamic characteristics when no physical prototype is available.