| In recent years,China's geological disasters have occurred frequently,seriously endangering the safety of people's lives and property,only in 2020,a total of 7840 geological disasters occurred nationwide,resulting in direct economic losses of 5.02 billion yuan,so the prevention and control of geological disasters has become a key issue.For landslides,mudslides,etc.in geological disasters,often use methods such as entering anti-slip piles for prevention and control,high efficiency hole formation is the key factor in effective prevention and control of geological disasters,conventional hole forming methods have manual hole drilling piles and rotary excavation into holes,but the construction speed is slow and dangerous,so the selection of suitable drilling technology and drilling tools is the guarantee of efficient drilling.Pneumatic DTH hammers are widely used in pile foundation construction,mine development,hydrological wells and emergency rescue due to their low drilling pressure requirements,high drilling speed of impact crushing rock,high drilling efficiency in hard rock and hard rock formations,clean energy and good formation adaptability.When the pneumatic DTH hammer impact slewing drills into the crushed rock,it is often due to the unreasonable selection of drill bit cloth teeth and impact work,resulting in faster drill bit wear,low drilling efficiency,large energy loss and other issues.Based on the above problems,it is necessary to study the drill bit cloth teeth of the DTH hammer,optimize the drill bit cloth teeth,improve the drilling efficiency and drill bit wear resistance,and ensure the rapid drilling and life of the DTH hammer.At present,there is less research on the back-cycle drill bit cloth teeth of large-diameter DTH hammers,so relying on the national key research and development plan "Research on the Miniaturization of Large Diameter Drilling Tools and Construction Machinery for the Prevention and Control of Large Diameter Holes in Landslides",the parameters of? 600 mm DTH hammer drill bits are studied in order to provide a theoretical basis for large-diameter drill teeth.In this paper,? 19 mm cemented carbide ball teeth were used to study hard rock and hard rock.Through the study and analysis of the single-tooth crushing mechanism of the free fall test bench,it can be seen that the crushing mechanism is: elastic deformation,fracturing,volumetric crushing three stages,and at the same time,the maximum diameter of the crushing pit in the case of five different sets of impact functions(20J,25 J,30J,35 J,40J)is about 22 mm,according to the optimal spacing of the cloth teeth of the maximum diameter of the single-tooth crushing pit,the three-tooth and five-tooth arrangement is designed,and the influence of different angles between adjacent spherical teeth on the impact of the crushing effect and the interaction between adjacent spherical teeth in the process of crushing.ABAQUS software was selected to establish the same model as the ball tooth and rock in the experiment,carry out numerical simulation analysis,observe the transmission of stress waves after the rock was impacted,and compare the effect of the stress wave superposition between the ball teeth at different angles on the rock fracture during the impact of the three teeth and the five teeth on the rock,and the fracture efficiency of the impact rock when the ball tooth positive pentagon arrangement impact rock was better than that of the positive triangle.After simulation and experimental analysis,when drilling into hard rock and hard rock,the single-tooth impact work adopts 40 J and 30 J impact work respectively,which can achieve the purpose of reducing the wear of the ball teeth and reducing energy loss.According to the measured tooth parameters,two large-diameter DTH hammer reverse circulation drills suitable for hard rock and hard rock drilling were independently designed,and considering the influence of rock chip particles on the reverse circulation effect during the back-cycle slag discharge process,the cuttings generated during the on-site construction of the experiment,simulation and large-diameter DTH hammer were measured,and compared with the slag discharge port with a diameter of ?30 to 50 mm in the drill bit,the designed drill bit can meet the needs of rapid drilling and effectively reverse cycle.In summary,the two types of drill bits designed can effectively reduce drill bit wear and energy loss,improve the efficiency and service life of pneumatic DTH hammer drilling,coupled with its simple construction and convenient maintenance,etc.,and can be widely used in geological disaster prevention and control construction,so that it can reduce time costs and complete geological disaster prevention and control work more efficiently. |
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