Hammer Drill Research Articles

Anti-Vibration Method for the Near-Bit Measurement While Drilling of Pneumatic Down-the-Hole Hammer Drilling

Pneumatic down-the-hole (DTH) hammer drilling technology has been used extensively in the fields of heat reservoir exploitation and geological exploration owing to its advantages of high efficiency and low pollution. However, the vibration near the bit is up to 40 g while DTH hammer drilling, which significantly affects the performance and longevity of the near-bit measurement while drilling (MWD). To enhance the environmental adaptability of the near-bit MWD in pneumatic DTH operations, a design method for a vibration-damping system based on the parameter optimization of a non-dominated sorting genetic algorithm II (NSGA-II) is proposed in this study. First, the whole structure of the near-bit MWD is designed, including the MWD sub-shell, sensors, measurement circuits, batteries, and connecting structures (the circuit unit). Secondly, this study analyzes the vibration characteristics of the pneumatic DTH hammer near the bit. According to the damping structure, the vibration response model for the circuit unit and the damping model are established. Thirdly, NSGA-II is employed to optimize the parameters of the damping model in terms of the low-frequency, high-intensity vibration characteristics near the bit in pneumatic DTH operations, thereby devising a damping scheme tailored to the unique conditions of DTH hammer drilling. Finally, vibration experiments were conducted to verify the effectiveness of the vibration-damping device. The experimental results indicate that within the vibration frequency range of 5–20 Hz and vibration level of 10–40 g, the peak attenuation rate of the circuit unit is more than 86.446%, and the improvement rate of the vibration stability of the system is more than 75.214%; the anti-vibration performance of the near-bit MWD system in DTH hammer drilling is improved remarkably. This study provides strong technical support for the stability of MWD equipment under such special working conditions. It has broad engineering application prospects.

Parametrical design and optimization of a reverse circulation drill bit for dust control

The reverse circulation down-the-hole air hammer drilling (RC-DTH) method is renowned for its efficiency in hard rock formations and exceptional dust control performance. It presents opportunities for cost-saving, efficiency improvement, energy conservation, and environmental protection. Reverse circulation drill bits are critical components of this method. This study focused on the air reverse circulation regime, investigating various geometric parameters of the RC drill bits through computational and experimental methods to enhance its dust control performance. Results indicate that increasing the layers of suction nozzles, enlarging the diameters of the suction and mixing nozzles, and optimizing the input airflow rate can effectively channel airflow toward the central passage of the drill tool. Consequently, this optimization significantly improves the dust control performance of the RC drill bits. Conversely, increases in the flushing nozzle diameter and alterations in the suction nozzle location have detrimental effects on the dust control capability of the RC drill bits. Field tests were conducted at the Yuan Jiacun iron mine, affiliated with Taiyuan Iron and Steel (Group) CO., LTD. The field tests demonstrate that the optimized RC drill bit exhibits excellent dust performance.

Development of a mathematical model and analysis of the dynamics of an electromechanical perforator with an impact-rotary mechanism

The object of the study is an electromechanical hammer drill with a rotary-impact mechanism. When studying the dynamics of an electromechanical hammer drill with a rotary-impact mechanism, methods of mathematical modeling and comparative analysis were used. A calculation scheme has been developed and, on its basis, the equations of motion of mechanical transmission elements and working tools of an electromechanical hammer drill with a rotating impact mechanism have been obtained. The solution of the resulting equations is carried out using the Runge-Kutta numerical method using the Mathcad computer program. When analyzing the dynamics of the elements of a rotary hammer with an impact-rotating mechanism, the value of the moment of resistance on the part of the rotating mechanism is taken as a variable parameter, since during the operation of the rotary hammer, with increasing drilling depth, the magnitude of the moment acting on the part of the tool increases. The dependences of the angular velocities of the elements of the hammer drill are given, which make it possible to select rational design parameters of the links of the electromechanical hammer drill using an impact-rotary mechanism.

ANALYSIS OF THE MANIFESTATION OF CRACKS IN ROCKS DURING HYDRAULIC HAMMER DRILLING

This article is devoted to the study of the process of crack formation in rocks during hydraulic hammer drilling. Analysis of the manifestation of cracks in rocks during hydraulic percussion drilling is a key aspect of research aimed at the optimization and efficiency of this drilling method. The article presents a comprehensive analysis of the mechanisms of crack formation in rocks under the influence of hydraulic shock waves, identifying factors influencing their development and propagation. The work highlights the basic principles and mechanisms of hydraulic percussion drilling, and also analyzes the factors influencing the formation of cracks in rocks during this drilling method. In addition, various parameters such as water pressure, impact velocity, tool type and rock characteristics are considered and their influence on fracture formation. The paper presents numerical modeling and calculation methods used to analyze the factors influencing the formation of cracks during well drilling. Basic parameters are considered, such as well depth, type of drilling equipment used, physical and mechanical properties of the rock, drilling fluid pressure and others. Examples of numerical calculations and modeling are given, as well as an assessment of the influence of various factors on the formation of cracks in rock. The purpose of this article is to summarize current information on the formation of cracks during the hydraulic percussion drilling method. The scientific significance of this study lies in the possibility of predicting and controlling the formation of cracks during hydraulic drilling, which contributes to more efficient use of resources and improved drilling safety. The results obtained can be used in the practice of geological exploration and mining work to optimize drilling processes and improve the quality of mineral extraction. Understanding the processes of formation of cracks in rocks with this drilling method will allow optimizing its use, improving control over the process and ensuring more efficient and safe extraction of minerals from the bowels of the earth.

The effect of feed force on vibration and productivity in hammer drilling: A machine-independent analysis excluding the effect of motor speed reduction

Construction workers usually use hammer drills to drill holes into hard materials for anchors or concrete screw installations. Vibration emission in the drilling process can cause various occupational diseases. Workers influence this process mainly by varying the feed force. A feed force variation in hammer drilling causes a machine-specific motor speed reduction. As it is impossible to distinguish the effect of feed force on vibration and productivity from machine-specific motor speed reduction effects, the findings of various studies on hammer drilling vary considerably. The goal of this study therefore is to identify the feed force effect on vibration and productivity, thus excluding machine-specific effects due to a motor speed reduction. We modified a hammer drill to keep motor speeds constant over a wide feed force range and conducted a drilling study using an automated drilling test rig. The drilling productivity increased with higher feed force, whereas machine-specific motor speed reduction led to a decrease. Evaluated with Cohen's f, both factors had a large effect (feed force: f = 0.62, motor speed: f = 0.42). An increasing feed force led to a higher vibration emission with a large effect (f = 1.03). Motor speed reduction reduced vibration with a small effect (f = 0.21). Further hammer drill studies are needed to specify machine-specific motor speed reductions for comparing the results of different studies. The isolated effects could be used by manufacturers to implement control strategies for automatic optimizations. Based on the feed force, motor speed could be varied to optimize vibration or productivity.

Impact Characteristics of a Bidirectional Pneumatic DTH Hammer for Unconsolidated Formations

With advantages of high efficiency and low cost, DTH hammer drilling has been highly applied in various drilling projects. When drilling in unconsolidated formations, it is prone to drilling accidents such as drilling tools sticking or burying. Thus, a bidirectional pneumatic DTH hammer is designed to drill boreholes using forward impact and release sticking drilling tools using backward impact. With a floating gas distribution mechanism, impact strokes of the DTH hammer piston can be changed when flat keys are in a different position of the key grooves on the gas distribution shaft. In drilling mode, the piston has a larger impact stroke and can impact the anvil at high speeds to drive the bit breaking rocks. When drilling tools become stuck, by changing to a smaller impact stroke, the piston can impact backward on the gas distribution valve to break rocks above the DTH hammer so sticking drilling tools can be released. According to the structure and working principle of the bidirectional pneumatic DTH hammer, a physical model based on the pneumatic transmission circuit is established; then, a simulation model is built with pneumatic transmission module components in software of SimulationX 4.1 student version. Piston velocities, displacements, and impact energy are analyzed, with main factors including piston mass, total weight of the DTH hammer, compressed air pressure, and backward impact stroke being considered. Analysis results show that working characteristics of the DTH hammer are fairly affected by piston mass and compressed air pressure. Based on the changing laws of the impact frequency, peak of impact velocity, and impact energy, a piston mass of 18 kg, total weight of 125 kg, gas source pressure of 2.2 MPa, and lifting distance of 60 mm for backward impact were recommended. To verify the performance of the bidirectional pneumatic DTH hammer, field experiments were carried out in the gravel stratums. The bidirectional DTH hammer was in good working condition and the maximum drilling rate can reach up to 1.5 m/min. By lifting the DTH hammer away from the bottom of the borehole and pumping compressed air, the DTH hammer piston could achieve a high frequency backward impact. There are no drilling tools’ sticking or burying accidents in the drilling experiments. The bidirectional pneumatic DTH hammer can effectively drill boreholes in loose formations and deal with drilling tools’ sticking or burying accidents.

Experimental investigation and CFD simulation of multiphase flow behavior in air reverse circulation drilling

In reverse circulation (RC) down-the-hole hammer (DTH) drilling, hole cleaning has a great impact on reducing accidents and improving efficiency. There is a technical difficulty in RC drilling to select the minimum air influx while keeping cuttings discharged smoothly according to different water invasion conditions. A novel experimental device was used to study the physics of multiphase flow associated with the cleaning process. Air influx required for cuttings transport was measured under different conditions in Rate of Penetration (ROP), cuttings diameter, and water yield, and influence among three factors were revealed. Furthermore, the computational fluid dynamic (CFD) method simulated and analyzed multiphase flow behavior. The results show that factors of ROP, cuttings diameter, and water yield obviously impact minimum air influx during the cuttings transport process. The accuracy and credibility of CFD method have been confirmed on account of reasonable agreement with experimental data (a relative error of less than 14% is achieved). The CFD simulation of multiphase transport reveals that cuttings velocity and pressure drop could be influenced by ROP, cuttings diameter, and water yield. Therefore, these factors should be carefully characterized during air RC drilling and hole cleaning to maximize the efficiency of cuttings transport.

VIBRATION REDUCTION OF A HAMMER DRILL WITH A TOP-DOWN DESIGN METHOD

AbstractDesigning vibrating systems is challenging due to component interaction. One approach to reduce the resulting complexity is top-down design where requirements on components are formulated such that the overall system achieves the design goal. Previous work showed how to derive quantitative and solution-neutral requirements on components of a vibrating system, expressed as permissible ranges of impedance. This work adapts the methodology to a practical use case and provides a concrete technical solution: A hammer drill that can cause white finger syndromes to users is equipped with an appropriate vibration absorber. The hammer drill is represented by a lumped mass model and validated using experimental data of a reference design. Solution-neutral and quantitative component requirements on the overall dynamics of the vibration absorber expressed by impedance are derived. They provide a clear target for the component design. A vibration absorber in form of a Tuned Mass Damper (TMD) is designed accordingly. The final design is validated experimentally and shown to reduce the vibration by 47%.

Analysis of the dynamic response and impact parameters of pneumatic down-the-hole hammer drilling rescue holes

The utilization of pneumatic DTH hammer drilling is the most efficient approach to rescue miners. The previous DTH hammer's impact model was simplified and the analysis of impact parameters was incomplete, hindering further drilling research. To enhance the rate of penetration (ROP) in downhole rescue drilling, this paper establishes a dynamics model for single impact drilling using a pneumatic DTH hammer. The model considers stress wave transmission between flexible components and derives response functions for the piston and drill bit. Through numerical simulation combined with engineering, the velocity-displacement response of the drill bit's bottom in the time and frequency domains is obtained. The effect of impact parameters on the displacement, velocity responses, and stress distribution of the piston and bit during impact is analysed. The results show that weight on bit has a large effect on the quasi-static response, and only focusing on vibration can ignore the static effect. The maximum value of the ROP occurs at the instant of impact, and its corresponding frequency represents the optimal impact frequency. These provide a theoretical reference for achieving higher construction speeds, greatly shortening the duration of mine accident rescue operations, and ensuring the safety of personnel trapped underground.

Influence of different parameters on drilling forces in automated drilling of concrete with industrial robots

The aim of this study is to analyse the forces between hammer drill and robot during automated concrete drilling. A series of tests was carried out with a 6-axis industrial robot system using an end effector newly-designed to hammer-drill concrete. The parameters investigated within the experiments consisted of three drilling directions, four drilling diameters and three feed rate levels which differ between the diameters. The results show that the drilling time decreases with higher feed rates, yet not proportional to the observed increase of drilling forces. Based on the obtained results further investigations need to be carried out to find adequate parameters for an optimal drilling process.

Dismantling of Reinforced Concrete Using Steam Pressure Cracking System: Drilling and Crack Propagation

This study investigated a new dismantling system for concrete structures using a steam pressure cracking agent. We improved the mechanical systems such that it can drill through reinforcing steel bars. Therefore, the control method of the system and shape of the drill tip were improved. When the drill tip is stuck with chips and stopped, it is automatically pulled out and reinserted to recover the rotation. By changing the tip angle of the drill bit from 75° to 90°, it became possible to cut reinforcing bars, which were difficult to cut previously. In addition, we designed a crawler-type mechanical system and improved it such that it can be moved to the appropriate position and operated at any angle. This study revealed that the energy required for the drilling process accounts for more than 90% of the total dismantling energy. Through experiments using an impact hammer drill and observations of fracture surfaces using a three-dimensional scanner, we analysed the characteristics of reinforced concrete. In addition, the feasibility of the design for dismantling reinforced concrete was confirmed based on the determined energy associated with crack propagation.

Factors on vibrational harm during hammer drilling – Influences of lateral force, feed force, hammer drill and drill bit type

When using hammer drills, the user is exposed to vibrations which can cause damage to the body. Those vibrations can be affected by external factors such as feed forces, which can increase the degree of damage to the user. However, currently there is a lack of knowledge as to whether the lateral forces applied by the user also have an influence on the technical system and whether these influences depend on the system. For this reason, a study with 1152 test runs was carried out on a test rig to investigate the relationship between the feed force and the lateral force as a function of the hammer drill setup on the vibrations at the hammer drill housing and main handle. The experiment showed that the feed (p = < .001, up to r = 0.57) and lateral (p = < .001, up to r = 0.77) forces had an influence on the vibrations of the hammer drill. However, these depended strongly on the technical system and hence cannot be generalized. Furthermore, it was proven that the impact frequency of the hammer drill was reduced by increasing both the feed force (p = < .001, r = 0.55) and the lateral force (p = < .001, r = 0.23). The findings can not only be used by engineers and scientists to further develop vibration standards, but also to design more ergonomic hammer drills. Hence, the vibration decoupling of hammer drills should be redesigned so that lateral forces do not lead to an increase in vibrations that are harmful to the user.

Does the user behavior effect the productivity of hammer drilling? – Analysis of the influences of feed and lateral force

The objective of this study was to investigate the relationship between feed and lateral force with productivity in hammer drilling. Necessary user forces and vibration caused by hammer drilling leads to user fatigue and long-term injuries. Through an increase in productivity, the stress duration and thus injuries caused can be reduced. The user, who influences productivity, applies lateral forces in addition to the feed force during hammer drilling. Their influence and interaction with the feed force on productivity has not yet been investigated. In this study, a total of 1152 boreholes were performed on an automated test bench. Along with the feed and lateral forces, the setup, consisting of hammer drill and drill bit model, was varied in order to investigate interaction effects as well as discuss transferability of the findings. The productivity was evaluated by the rate of penetration (ROP). It was observed that the ROP decreased with increasing lateral forces (p < .001, r = 0.315) and increased with increasing feed force. The detailed courses of these relationships were setup-specific. At low feed forces, the feed and lateral force interacted on the ROP. The investigated relationships indicate an efficient operating range depending on the user forces and setup used, which enables a reduction of the user's stress duration. The findings help engineers develop power tools that provide more efficient and hence less fatiguing work, making them more ergonomic for the user.

Mechanical Response of Stress Wave Attenuator With Layered Structure Under Impact Load: Experimental and Numerical Studies

Abstract The fluidic down-the-hole (DTH) hammer drilling is generally regarded as one of the best means for hot dry rock (HDR) drilling. The fluid oscillator, as the core part of the fluidic DTH hammer, is prone to fracture when subjected to impact loads due to its brittle characteristics. Therefore, a steel-layered structure with different contact areas is developed as a stress wave attenuator to protect the fluid oscillator for the DTH hammer under high-temperature drilling conditions. In this paper, the stress wave attenuation performance with different steel-layered structures is analyzed based on the split Hopkinson pressure bar (SHPB) technique. The effects of contact area ratio, the orientation of contact surfaces, and number of layers on the stress wave attenuation are investigated by numerical simulations and laboratory tests. It is found that the attenuation ratios in stress amplitude and impact energy gradually increased with the increase of the contact area ratio. Besides, the orientation of contact surfaces has a significant influence on the attenuation effect. For the layered structure with a two-layer object part, the maximum attenuation ratios of stress amplitude and impact energy are 62.4% and 79.6%, respectively, when the included angle between the two convex structures is increased to 90 deg. Additionally, the attenuation ratio of the layered structure can be improved by increasing the number of layers. The results demonstrate that the stress wave attenuator with layered structures has great potential for brittle materials protection against impact loads.

Management of stenosing flexor tenosynovitis in primary care.

Management of stenosing flexor tenosynovitis in primary care.

Methodology for Analysing Risk Factor on Surface Top Hammer Drill Rig

Methodology for Analysing Risk Factor on Surface Top Hammer Drill Rig

Review of high-temperature geothermal drilling and exploitation technologies

Global warming induced by excessive carbon dioxide emission generated from fossil fuels consumption is becoming increasingly severe. Development and utilization of clean and renewable energy is a significant measure to contribute for the carbon neutrality. Geothermal resource is an important clean and renewable energy, because of its advantages of abundant reserves, exploitation without restrictions from the climate and season. Extracting heat from the high temperature geothermal reservoir requires well drilling, completion and fracturing. However, due to some particular conditions in geothermal development, such as high temperature, erosion, leakage, and hard rocks, traditional petroleum well drilling and completion technologies are not well applicable in the geothermal industry. In this paper, the state-of-the-art geothermal drilling, and completion technologies as well as several fracturing methods, such as foam drilling, air hammer drilling, hydrothermal jet drilling, expansion casing technology, high temperature resistant drilling fluid and cement, chemical stimulation and thermal stimulation are comprehensively reviewed. Besides, heat extraction performances of water and CO2 as working fluids in the geothermal system are discussed. A few novel heat extraction methods including closed loop, open loop, enhanced geothermal systems are compared and analyzed. This review is expected to provide suggestions for research fields worthy of study for geothermal drilling and exploitation.

Analysis of the influence of feed and lateral force on productivity and hand-arm vibration in interaction with drill bit wear and concrete strength

The productivity and vibration are important aspects of the ergonomic evaluation of hammer drills and are influenced by drill bit wear and the feed force. In addition, the user applies a lateral force. The influence of the lateral forces in interaction with the drill bit wear on productivity and hand arm vibration (HAV) has not been investigated yet. In this study, first, the influence of the feed and lateral force on drill bit wear was investigated and subsequently how this wear interacts with the user forces to change hammer drill vibration and the rate of penetration. Furthermore, the concrete strength and the drill bit manufacturers were varied. The experiment was performed on a robot-based test rig with a total of 4800 boreholes. The rate of penetration, the hammer drill vibrations, and the wear of the drill bit were measured. It could be shown that the lateral force has a strong effect on the helix diameter wear (p < .001). Furthermore, the feed and lateral force each had an influence on the hammer drill vibration (each p < .001) and on the rate of penetration (each p < .001). The lateral force in interaction with the drill bit wear changed the vibration at the main handle. Further, it could be shown that the wear pattern varies depending on the concrete strength and drill bit manufacturer. These findings help manufacturers in developing reliable and ergonomic products and for class societies in designing standards for HAV.

Mechanical Analysis and Structural Optimization of Air Hammer Drill Teeth Based on ANSYS /LS_DYNA

Air drilling is a prevailing technology of oil and gas energy industry in today’s world, it can solve problems when drilling in complex layer that can not be done by conventional drilling way. At the same time, some failures of dill bit teeth in air hammer drilling like teeth falling, breaking and severe abrasion seriously affect the drilling efficiency. Thus this paper intended to investigate rock breaking criteria and damage constitutive model, establish a finite element simulation model of single tooth rock breaking and use the impact of dynamic finite element software ANSYS/LS-DYNA to analysis characteristics of rock crushing under confining pressure, which includes fragmentation process, drilling tooth impact and the crush volume of rock broken. The study found that the tapered tooth has the highest efficiency in rock breaking under the same conditions and with edge teeth at 25°angle that increases the rock crushing volume significantly. In addition, the configuration of tooth surface was examined, which showed that the pattern of “spherical teeth in the middle and tapered teeth in the peripheral” has highest rock breaking efficiency.

Mechanical Analysis and Structural Optimization of Air Hammer Drill Teeth Based on ANSYS /LS_DYNA

Air drilling is a prevailing technology of oil and gas energy industry in today’s world, it can solve problems when drilling in complex layer that can not be done by conventional drilling way. At the same time, some failures of dill bit teeth in air hammer drilling like teeth falling, breaking and severe abrasion seriously affect the drilling efficiency. Thus this paper intended to investigate rock breaking criteria and damage constitutive model, establish a finite element simulation model of single tooth rock breaking and use the impact of dynamic finite element software ANSYS/LS-DYNA to analysis characteristics of rock crushing under confining pressure, which includes fragmentation process, drilling tooth impact and the crush volume of rock broken. The study found that the tapered tooth has the highest efficiency in rock breaking under the same conditions and with edge teeth at 25°angle that increases the rock crushing volume significantly. In addition, the configuration of tooth surface was examined, which showed that the pattern of “spherical teeth in the middle and tapered teeth in the peripheral” has highest rock breaking efficiency.