Search

ObjectiveThe objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire.Samples24 pairs of rabbit femora.MethodsAfter drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated.ResultsThe work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types.Clinical relevanceMechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit.

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. [ABSTRACT FROM AUTHOR]

OBJECTIVE The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire. SAMPLES 24 pairs of rabbit femora. METHODS After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated. RESULTS The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types. CLINICAL RELEVANCE Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit. [ABSTRACT FROM AUTHOR]

Modern mining enterprises widely use rotary drilling rigs equipped with ball drill heads, which are used to drill holes ∅250 - ∅320 mm in hard rocks for blasting operations. Drilling of such wells is associated with the use of significant axial forces and torques, which cause longitudinal deformation (compression) and torsional deformation of the rods and the drillstock as a whole. Therefore, the intensification of rotary drilling processes to increase the diameter of the drilled well is associated with significant technical difficulties and economic costs. In a number of practical cases, it is possible to drill large diameter wells in two stages. The first stage involves drilling a small-diameter (∅250 - ∅320 mm) advance well from the outer horizons of a mining enterprise (e.g., a mine) to a lower horizon or a network of horizontal workings connected to a pit. After drilling the advance borehole (∅250 - ∅320 mm), a drill bit is lowered to the horizon below, which is put on a drill bit instead of a small diameter crown. After replacing the working tool with a diameter of ∅250 - ∅320 mm with a drill bit with a diameter of ∅1500 - ∅3000 mm, drilling is carried out vertically upwards (sometimes at an angle). When drilling, the drill stand is subjected to torque and tensile axial force. In this mode of operation, the loads on the drillstring increase significantly, but the longitudinal axis of the drillstring remains straight, as the influence of longitudinal bending is eliminated, and the influence of drillstring unbalance due to initial misalignment and centrifugal forces is reduced. However, the moment of friction forces during drilling increases significantly, the influence of the drillstring stiffness increases, and there is a possibility of longer stops during the driller's operation in the bottom hole, while the value of the elastic forces of the drillstring decreases with an increase in its length, and therefore the twist angle increases. In the case of an increase in the angle of rotation of the drill string, the dynamic torque and tangential stresses increase due to significant differences in the angular speed of rotation of the string (from to 0). In this case, there are significant changes in the kinetic energy of the pile with a decrease in the angular velocity of its rotation. In fact, a decrease in the rigidity of the mill leads to an increase in the increase in the kinetic energy of the system on the drill. That is, the dynamic angle of shaft torsion increases and leads to the manifestation of a torsional impact with a large coefficient of dynamism (). As follows from the industrial tests of the 2KV 3000 machine, the possibility of a torsional impact in the driller-drillstock-rotator system under the influence of a variable torque of friction forces between the rock and the tool was not taken into account. Therefore, at the maximum length of the drillstring, the increase in the kinetic energy of the impact causes the largest dynamic angle of twisting of the drillstring, which is perceived by the first rods from the driller, and they experience the ultimate induced normal stresses that lead to rod breakage. For these reasons, for the efficient operation of drilling rigs in the drilling mode, it is necessary to create and apply an engineering methodology for calculating the dynamic parameters of the drill string and the rig as a whole under the influence of the frictional interaction between the tool and the rock. [ABSTRACT FROM AUTHOR]

The application of high-frequency vibrations to a drill bit is a promising means of increasing rate of penetration in deep hard formations. The implementation of such drill bit high-frequency vibrations is possible by installing the cavitation hydraulic vibrator in the drill string in front of the rock-cutting tool. Purpose. Evaluation of resonant modes (frequencies of oscillations) for the dynamic interaction of the mud pressure in the drill string and the drill bit longitudinal vibrations in case of contact with the rock being destroyed while drilling using the cavitation hydraulic vibrator; comparative analysis of the effectiveness of using a high-frequency mechanical vibrator and a cavitation hydraulic vibrator in case of drilling in hard rocks. Methodology. The research is based on a comparative analysis of the amplitudes and power spectral density of mud pressure oscillations of the mud and vibration accelerations in the drill bit cross section of drill string. Findings. The results are presented in the form of amplitude spectra and power spectral densities of mud pressure and vibration acceleration, as well as the dependence of the increase in the rate of penetration on the frequency of forced oscillations of the drill bit. Originality. Taking into account the influence of the cavitation hydraulic vibrator on the drill rig ROP made it possible: - to determine the resonant frequencies of pressure oscillations of the mud of the drilling tool, for the effective removal of drilled rock at the point of its contact with the drilling tool, and the longitudinal vibration accelerations of the drilling tool, to speed up rate of penetration during the construction of a well; - to evaluate the effectiveness of using a cavitation hydraulic vibrator in comparison with a high-frequency mechanical vibrator. For the studied modes of operation of the hydraulic vibrator at values of the cavitation parameter τ = 0.19, the well rate of penetration increases by 40 % compared to the traditional rotary method and by 26 % compared to the vibratory hammer. For the cavitation operating mode of the hydraulic vibrator τ = 0.41, the increase in the rate of penetration is 62 and 37 %, respectively. At the same time, the operating efficiency of the hydraulic vibrator was ensured at the resonant frequencies of the mud pressure with a frequency of 1,580 Hz at τ = 0.19 and 1,980 Hz at τ = 0.41. Practical value. For a specific design of the cavitation hydraulic vibrator as part of a drill string, by changing the frequency of the drill bit vibration impact on the rock, resonant frequencies are established that ensure the high ROP of the well. [ABSTRACT FROM AUTHOR]

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.

Copyright of Konya Journal of Engineering Sciences / Konya Mühendislik Bilimleri Dergisi is the property of Selcuk University Journal of Engineering, Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This report details the case of a 69-year-old male who had presented to the emergency department at the suggestion of his dentist after ingesting a diamond-tipped drill bit during a routine dental procedure. Through the use of radiograph, computed tomography, and colonoscopy, the drill bit was determined to be lodged in the distal vermiform appendix. Throughout his clinical course, the patient remained asymptomatic but was monitored closely for signs of complications of a retained foreign body in the appendix. Gastroenterology and general surgery were consulted on the case but ultimately non-surgical approaches prevailed and the drill bit passed in the stool. This patient's case highlights the success of noninvasive measures for appendiceal foreign body removal. [ABSTRACT FROM AUTHOR]

Introduction: The shift from manual to machine-based operations has also affected the creation of cartilage defect models. Manual drilling lacks precision and consistency compared to power drills, which offer controlled speed and depth. Moreover, manual burrs may produce defects with irregular edges and uneven surfaces. We introduce a superior method utilizing a power drill with a brad point bit to overcome these limitations, ensuring precision, consistency, and ergonomics. Methods: Our innovative approach uses a brad point drill bit to generate cartilage repair animal models. Tissue sections on day 90 were stained using Hematoxylin and Eosin, Safranin-O, and Masson's trichrome to assess proteoglycan and collagen contents. In contrast, differentiation of hyaline cartilage was evaluated using RGB trichrome staining. Results: This technique can be considered refined compared to conventional methods. The spur-cutting edges bring down splintering, resulting in a smooth, clean defect. The wide flute in the drill bit helps in the smooth and continuous outflow of debris without plugging into the defect. The histological and radiographic findings demonstrated the suitability of these models for proficiently creating and assessing cartilage regeneration over 90 days. Conclusion: Although preliminary findings are promising, further studies will be helpful to standardize and establish this technique. This proof of concept paper provides a foundation for future studies that aim to compare the animal model with other existing models, emphasizing the need for further investigation.

Drill bits with internal cooling capabilities are still not employed in stone machining practices within shop floor environments. Therefore, a conventional industrial drill bit used in stone machining was subject to a redesign wherein an axial cooling channel was machined throughout its body. A comparison was drawn between the standard drill bit without cooling capabilities and the redesigned drill bit, which used compressed air as a cooling medium. The experiment was performed by drilling three types of stone samples varying in hardness with nine combinations of cutting speed and feed rate. During the machining process, two types of process signals were continuously measured—namely, cutting forces and vibrations. Additionally, the cutting edges of the drill bits were inspected after a specific number of drilling cycles using a vision system. The primary objective of this study was to compare the cutting forces and tool wear dynamics achieved by those two drill bits. Furthermore, the usage of vibration signals in the classification of stone hardness during machining with an internally cooled drill bit was additionally analyzed. The results of this study unveiled improvement in minimizing cutting forces, vibrations, and the intensity of tool wear when utilizing an internally cooled drill bit. Even though the machining system generally exhibited lower vibrations, vibration signals again demonstrated commendable efficacy in classifying stone hardness. [ABSTRACT FROM AUTHOR]

The choice of bits is a crucial factor for drilling performance in deep and hard-to-drill formations. This paper explores the characteristics, application scopes, and performance advantages of various shaped cutters that are used in PDC (Polycrystalline Diamond Compact) bits. It also examines the suitability and effectiveness of PDC bits, hybrid bits, and roller cone bits for different kinds of hard-to-drill lithologies. The paper offers a reference for bit selection in challenging drilling conditions. [ABSTRACT FROM AUTHOR]

In deep unconventional oil and gas development, the problem faced is that PDC bits are eroded by solid-liquid high-speed fluids, resulting in damage. It has led to serious damage to the stability of the drill bit, a decrease in the service life of the drill bit, and an increase in the difficulty in efficient drilling. The essence is that the surface hardness and erosion resistance of the drill bit are not strong enough. Therefore, improving the stability of drill bits is a crucial and urgent problem to be solved. In this paper, Ni60A + 20% WC + 0.3% graphene composite coatings were prepared on a Q235 steel substrate, which is a new type of high hardness coating. Moreover, the effects of microstructure and microhardness of the composite coatings at different laser powers (800 W, 1200 W, 1600 W, and 2000 W) were investigated. The results show that the laser power can significantly affect the microstructure of the coating. The phase composition of the composite coatings is essentially the same at different laser powers. However, there are significant differences in the content of each phase. When the laser power is higher than 1200W, the content of M23C6, Cr3C2 and Fe3C in the composite coating increases and the microhardness of the coating decreases. When the laser power is below 1200 W, the dilution rate of the substrate is low and a metallurgical bond cannot be formed between the composite coating and the substrate.

A feature of reverse circulation pneumatic down-the-hole (DTH) hammer drilling system is its ability to reduce the emission of respirable dust which is known to be harmful to drilling workers and equipment. The enhanced dust control performance of the drilling system requires better understanding and insight into the airflow behavior at the bottom of the borehole. To investigate the transportation and distribution of cuttings under various drilling parameters, and to evaluate the dust control performance, we conducted a series of simulations using computational fluid dynamics (CFD) multiphase modeling. Finite volume analysis was performed on a reverse circulation drill bit with an optimized structure reported in a previous study. The results show that increasing the input airflow rate can directly improve the dust control efficiency. The rising value in terms of cuttings feed concentration, rate of penetration (ROP), particle diameter, and specularity coefficient would decrease the dust control performance. Furthermore, the characteristics of the cutting distribution vary with the operating parameters and demonstrate the multiphase flow pattern in the RC-bit. This work may provide instructive insights into cutting transportation under various drilling parameters commonly considered in the drilling process and promote the development of dust suppression with efficient drilling operations.

An offset of roller cone rotation centerlines is used to increase the mechanical penetration rate while drilling in soft rocks. This enables increasing the area of a cutting structure teeth contact with a bottom hole. The analysis of offset cone drill bit (cutting structure) teeth wear showed that particularly significant wear is characteristic of the transition zone from the heel cone to the nose cone; which leads to significant reduction in the mechanical rate of penetration and a rapid decrease in the hole diameter. The purpose of this paper is to conduct a theoretical research on the nature and conditions of interaction between heel and peripheral nose cones of offset roller cone bits with a bottom hole; which is aimed at improving the efficiency of rock cutting by offset roller cone bits. To achieve the purpose; the authors analyzed data on the nature and causes of wear of existing offset roller cone bit cutting structure (teeth); developed a mathematical model in a cylindrical coordinate system allowing to determine the location and geometric parameters of the gage cone contact area with the hole wall for different roller cone bits sizes; developed a computer solid model for checking the adequacy of the mathematical model by comparing these two models; prepared recommendations for further improvement of the design of existing offset roller cone bit cutting structure (teeth). The research was carried out by the method of mathematical simulation of geometric figures and bodies corresponding to roller cones and a hole. The research has revealed that significant adjustments need to be made to the geometry of the roller cone teeth (currently being patented). This would allow decreasing the areas of cone heel blunting by 15–20 % as well as providing more prolonged contact of base and gage cones with bottom hole and wall surfaces. This allows to reduce wear of teeth in the transition zone of the generatrix from the peripheral nose cone to the gage (heel) cone of the roller cone and to maintain the required specific pressure on the cut rock for a longer period of time and; as a result; to increase both the mechanical penetration rate and the service life of the drilling tools.

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Implant stability significantly impacts accelerated osseointegration, leading to faster patient recovery. Both primary and secondary stability necessitates superior bone-implant contact influenced by the surgical tool required to prepare the final osteotomy site. Besides, excessive shearing and frictional forces generate heat causing local tissue necrosis. Hence, surgical procedure necessitates proper irrigation with water to minimize heat generation. Notably, the water irrigation system removes bone chips and osseous coagulums, which may help accelerate osseointegration and improve bone-implant contact. The inferior bone-implant contact and thermal necrosis at the osteotomy site are primarily responsible for poor osseointegration and eventual failure. Therefore, optimizing tool geometry is key to minimizing shear force, heat generation, and necrosis during final osteotomy site preparation.The present study explores modified drilling tool geometry, especially cutting edge for osteotomy site preparation. The mathematical modeling is used to find out ideal cutting-edge geometry that facilitates drilling under relatively less operational force (0.55–5.24 N) and torque (98.8-154.5 N-mm) with a significant reduction (28.78%–30.87%) in heat generation. Twenty-three conceivable designs were obtained using the mathematical model; however, only three have shown promising results in static structural FEM platforms. These drill bits are designed for the final drilling operation and need to be carried out during the final osteotomy site preparation.

A feature of reverse circulation pneumatic down-the-hole (DTH) hammer drilling system is its ability to reduce the emission of respirable dust which is known to be harmful to drilling workers and equipment. The enhanced dust control performance of the drilling system requires better understanding and insight into the airflow behavior at the bottom of the borehole. To investigate the transportation and distribution of cuttings under various drilling parameters, and to evaluate the dust control performance, we conducted a series of simulations using computational fluid dynamics (CFD) multiphase modeling. Finite volume analysis was performed on a reverse circulation drill bit with an optimized structure reported in a previous study. The results show that increasing the input airflow rate can directly improve the dust control efficiency. The rising value in terms of cuttings feed concentration, rate of penetration (ROP), particle diameter, and specularity coefficient would decrease the dust control performance. Furthermore, the characteristics of the cutting distribution vary with the operating parameters and demonstrate the multiphase flow pattern in the RC-bit. This work may provide instructive insights into cutting transportation under various drilling parameters commonly considered in the drilling process and promote the development of dust suppression with efficient drilling operations. [ABSTRACT FROM AUTHOR]

Drill bits with internal cooling capabilities are still not employed in stone machining practices within shop floor environments. Therefore, a conventional industrial drill bit used in stone machining was subject to a redesign wherein an axial cooling channel was machined throughout its body. A comparison was drawn between the standard drill bit without cooling capabilities and the redesigned drill bit, which used compressed air as a cooling medium. The experiment was performed by drilling three types of stone samples varying in hardness with nine combinations of cutting speed and feed rate. During the machining process, two types of process signals were continuously measured—namely, cutting forces and vibrations. Additionally, the cutting edges of the drill bits were inspected after a specific number of drilling cycles using a vision system. The primary objective of this study was to compare the cutting forces and tool wear dynamics achieved by those two drill bits. Furthermore, the usage of vibration signals in the classification of stone hardness during machining with an internally cooled drill bit was additionally analyzed. The results of this study unveiled improvement in minimizing cutting forces, vibrations, and the intensity of tool wear when utilizing an internally cooled drill bit. Even though the machining system generally exhibited lower vibrations, vibration signals again demonstrated commendable efficacy in classifying stone hardness.

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Histologically evaluate damage to rabbit femur after the creation of bicortical 1.5-mm-diameter holes using a standard surgical drill bit, an acrylic drill bit, and a Kirschner wire (K-wire)., Methods: 10 femora (5 pairs) from skeletally mature female intact New Zealand white rabbits were used. The bone diaphyses were divided into 4 locations, systematically undergoing each test (surgical drill bit, acrylic drill bit, K-wire, and intact control). Four pairs were drilled using a mechanical testing machine, and 1 pair was drilled by hand. Cross-sections of the bone were stained en bloc with basic fuchsin for undecalcified histological evaluation. Damaged bone was reported as a percentage of a standardized area and categorized by location (cis- or transcortex), drill contact (entrance or exit of the cortex), and total damage (both cortices)., Results: The drilling method (hand vs mechanical testing machine) had no effect on histologic damage, so results were analyzed by combining all data. The K-wire demonstrated the greatest area of cracks/damage compared to both standard surgical and acrylic drill bits, whereas no difference in damage was noted between the 2 drill bits for all variables., Conclusions: The K-wire and drill bits caused microdamage; K-wire drilling created more microdamage than drill bits., Clinical Relevance: The rabbit bone cortex is thin and brittle relative to dogs and cats, leading to failure during and after fracture fixation. The clinical failure of rabbit bone is at least partially caused by drill bits or K-wires causing microcracks.

The optimization of drilling operations is an ongoing necessity since the major proportion of the terrestrial hydrocarbon reservoirs has been exhausted. Furthermore, there is a growing tendency among the space exploration agencies to drill the subsurface formations of the remote planets, such as the Moon and Mars. To optimize the drilling efficiency in such complicated conditions, the mechanical specific energy (MSE) must be efficiently reduced. The available MSE models incorporate the different parameters related to the surface rig, drill bit, and the underlying rocks to estimate the MSE values. In this research, the current status of those MSE models is assessed, and their relevant assumptions, limitations, applications, and pros and cons are profoundly argued. From the current scrutiny, it was deduced that the available MSE models require more geomechanical parameters to be included in their formulations. Furthermore, the use of artificial intelligence (AI) techniques was identified as an effective solution to incorporate such geomechanical parameters in the MSE models. Moreover, the establishment of suitable MSE models for off-Earth drilling applications was also revealed to be very urgent and essential. The performed analyses together with the comparative assessments are contributing factors for the modification and establishment of future MSE models. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) bits have been widely used in oil and gas well drilling and have recently also begun to be used in geothermal well drilling. In the present study, the drilling performance and wear of a PDC bit were assessed by laboratory drilling tests. The correlation between the progress of bit wear and some indexes of rock abrasivity was discussed referring to the test results. The rate of penetration was formulated as a function of weight on the bit using the drilling test results for other PDC bits with the same geometric design as that used in the present study and introducing a parameter that represents the drilling performance of the bit. The parameter was found to be exponentially reduced with the wear volume of the polycrystalline diamond layer. The parameter was also found to be associated with the drilled rock type. [ABSTRACT FROM AUTHOR]

High-frequency torsional vibration percussive drilling is considered a promising approach to improve drilling performance in deep hard formations, so studying its rock breaking mechanism and effect is the essential and basic issue. Compared with percussive-rotary drilling and high-pressure jet drilling, it can increase the service life of drilling tools and reduce drilling cost significantly. In this paper, based on elastic mechanics and principles of mechanical vibration, the cutting mechanism model of PDC (polycrystalline diamond compact) drill bit cutter and the amplitude–frequency characteristic model of steady-state vibration response of rock system are established, as well as the response characteristics of the rock system are also pointed out. Based on elastic–plastic mechanics and rock mechanics, Drucker–Prager criterion is adopted as the constitutive equation of rock, and plastic strain is used as the criterion of rock failure. Moreover, the model of rock damage failure is also established. The effect of exciting frequency on ROP (rate of penetration) has been studied by carrying out rock breaking test using high-frequency torsional vibration percussive drilling of PDC drill bit along with analyzing and handling test data. The study results show that when torsional vibration percussive frequency is approximately equal to inherent frequency of the rock, rock resonates with cutter, the plastic strain and ROP reach maximum, and drilling efficiency is the highest. The research results can help to deepen the understanding of the percussive drilling with high-frequency torsion vibration and provide useful insight into the design, application, and optimization of this new type of downhole tools in drilling engineering. [ABSTRACT FROM AUTHOR]

Copyright of Revista Fuentes, El Reventón Energético is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We compared the performance of drill bits with a diamond-containing combined matrix, equipped with inserts of a diamond-containing heat-resistant composite material DCTM and inserts of diamond powders obtained by activated HPHT sintering with the addition of n-layer graphene grade N002-PDR, and assessed the wear resistance of a new wear-resistant composite material DCWM. A complex of studies carried out after drilling a block of Korostyshevsky X category granite at a special stand, including the microscopic study of the working surface of the combined diamond-containing matrix of drill bits, the contact measuring the roughness, and the investigation of the microprofile of the bottomhole surface formed during drilling, yielded a conclusion about higher performance of crowns equipped with DCWM inserts compared to crowns with DCTM inserts. [ABSTRACT FROM AUTHOR]

Drilling process is one of the most common machning process in industrial sector. More than half of the metal-cutting processes are conducted by the drilling process. Drill bit has influenced the results of the drilling process. Therefore, selection of the suitable drill bit becomes a critical factor in the drilling process. This is because the use of the suitable drill bit could fulfill the determined specification value of the hole. Six Sigma and Failure Mode Effect Analysis (FMEA) methods are used to identify factors that have influenced the results of the drilling process. Then by using the Design of Experiment, selection of the best drill bit could be done. In this study, 2 factors that influenced the result are the drill bit type and the drill point angle. Significance test using nested design through MINITAB 14 application has shown that both factors have significant influence over the hole diameter size.. Then by using the plot from the MINITAB 14 application, HPMT 1 became the best drill bit because it could fulfill the specification value. As for the best point angle in this study is 139.72º. Process capability calculation of HPMT 1 has shown that the process is in control. The conclusion is that drill bit HPMT 1 with point angle 139.72º became the best option in this study.

A new type of ice core drill bit, designed with a vane swirler, was developed for ice core drilling with air reverse circulation. An orthogonal experimental design method was employed to investigate the effects of the swirler structure parameters on the reverse circulation performance of the drill bit including helical angle, number of blades, blade length and blade central angle, etc. The entrainment ratio was used to evaluate the reverse circulation effectiveness of the drill bit. The results show that the helical angle is the dominant factor regardless of whether or not the flushing nozzles are part of the design of the drill bit. The number of blades is the least important factor for the drill bit designed with the flushing nozzles (referred to as drill bit I), while the outlet area of the swirling slot is the least influential factor for the drill bit without flushing nozzles (referred to as drill bit П). In addition, the appearance of the ice core has a certain effect on the air reverse circulation for both drill bits. Within the ranges of this study, the optimal structure of the drill bit was determined based on the range analysis of the orthogonal design.

Relevance. The main drilling development direction is improving technical and economic indicators. The main direction is the new rock-cutting tools generation, which ensures the effective rock destruction. To improve the technical and economic drilling indicators it is necessary to study the processes occurring during well drilling. Often the processes are complex and need to be detailed. This applies to narrow, hard-to-reach places in the bottomhole zone. In some cases, experimental research methods are difficult, expensive, or completely unavailable. In addition, the main modern requirement for scientific research is an integrated approach. It consists in a comprehensive and simultaneous consideration of all processes occurring during well drilling. In this regard, a relevant method is the computer simulation. This method studying drilling accurately, visually and reliably. The aim of the research is the computer simulation of the processes occurring during drilling. Objects: processes occurring during well drilling. Methods: simulation modeling, analytical studies, analysis. Results. The authors have identified the main drilling processes that need to be explored in the design and development of a new generation rock cutting tools. The paper considers the possibilities of computer modeling in study of drilling with diamond crowns. On the simplified model example for the interaction of rock cutting tools with rocks, software products are given. The results of their use are shown: the thickness of a rock layer removed by any diamond crowns, the tool location coordinates at any time, the heating temperature of the diamond single-layer crown, the distribution of mechanical stresses. The authors compared the modeling of the same drilling processes using different software products. The features, modeling accuracy of drilling processes are revealed. The computer simulation of drilling processes is grounded. The paper demonstrates the advantages of computer simulation over the experiment.

Drilling is a major component of mining operations and must be efficient in order to achieve an economic production cycle. The main objective of this research is to utilize numerical approaches in the prediction of bit wear rather than laborious, time-consuming, and expensive lab tests. This research used three-dimensional continuum modeling to study the effect of rock and drill bit material, drill speed, and feed rate on the interaction of rock and bit material. In addition, three-dimensional discontinuum modeling was used to validate the previous modeling and to investigate workpiece fragmentation. The rock types evaluated were quartz, limestone, and copper, and the bit materials tested were 76-mm tungsten-carbide (T-C) and polycrystalline diamond compact (PDC). The maximum bit wear depth was 64 mm which occurred with T-C bit and quartz as the workpiece. Tool wear depth was five times higher for copper (0.001 mm) than limestone for a given drilling time. In the discontinuum model, the effect of rotational speed and feed rate on rock fragmentation were simulated. The approach can be used for different purposes by varying the defined parameters in this paper. [ABSTRACT FROM AUTHOR]

Purpose. To develop a method for assessing the drill string hydraulic energy based on mathematical modeling of dynamic processes at the ‘drill string with a hydraulic vibrator – rock’ system, taking into account the nonlinear dependence of system dissipative losses on the drill string vibration amplitudes at drill operating modes. Methodology. Methods are based on experimental and theoretical studies on the drill string dynamic parameters and the evaluation of efficiency of converting stationary fluid flow into pulsating flow. Findings. The results are presented in the form of calculated and experimental dependences of pressure, volumetric flow rate, vibration accelerations and hydraulic vibrational power in the section of the rock cutting tool on the criterion parameter of cavitation t. Originality. Taking into account the influence of the string elements’ vibration amplitude on dissipative losses, made it possible to obtain an acceptable agreement with the drilling experimental data as well as: - to determine the peak to peak (from 43.5 to 9.8 kW) and average (from 9.8 to 2.35 kW) values of hydraulic oscillatory power at the cavitation parameter range t = 0.12–0.475; - to evaluate the efficiency of converting the drilling fluid stationary flow power at the inlet to the hydraulic vibrator into the oscillatory power (for the oscillation period) on the rock cutting tool. Within the investigated range of the drilling operation parameter, the maximum calculated value of the efficiency was approximately 76 % with the value of the cavitation parameter t equal to 0.16, and the minimum efficiency value was 19 % at t = 0.475. Practical value. Practical value of the results obtained is that the improved mathematical model of the ‘drill-rock’ dynamic system allows establishing a rational mode of cavitation hydraulic vibrator operation at the drill string design stage to implement acceptable levels of hydraulic power on the drill bit. [ABSTRACT FROM AUTHOR]

In order to improve the ROP (rate of penetration) of complex structure and deep wells and reduce the energy consumption of rock breaking during the drilling process, a core drill bit with negative pressure adsorption effect is developed. Rock-breaking energy consumption, ROP, negative pressure effect and rock carrying capacity of new drill bit are studied. Numerical example is conducted to analyze the relationship between the characteristic parameters of drill bit and cutting velocity and experimental tests are carried out to verify the theoretical model and the results of calculation examples. The calculation results indicate that with the increase in the cutting velocity, the axial and tangential forces and the ROP increase and the power consumption of drill bit decreases. The nozzle equivalent size of the new drill bit can be designed as 0.03 mm. According to the experimental results, as the flow rate of fluid increases, the power consumption of new drill bit decreases and the ROP increases. Compared with the conventional bit, the reduced ratio of power consumption of new drill bit is between 8% and 25%, and the ROP is increased by more than 45% in some sections, which show the rock breaking effect of new drill bit is better. The new drill bit can be used in the exploitation of oil and gas well drilling technology with new conditions, and also can provide technical support for improving rock breaking efficiency and ROP in the drilling process. [ABSTRACT FROM AUTHOR]

Bone biopsies whether Computed Tomography guided or open, are one of the commonest procedures undertaken. Our literature review proves that bone biopsy needle fracture in a bone is a rare complication with no literature available on a needle fracture in a joint. We report a 7-year-old male who underwent an open needle biopsy. During the procedure, the bone biopsy needle fractured with the distal 2.7 cm fragment being completely embedded in the right sacroiliac joint. Considering the location of the fragment, the standard techniques described in literature for extraction could not be applied due to intra-articular nature of the fragment and the risk of complications. We describe a method using a 2.5 mm drill bit to safely extract the foreign body. We have found that reasonable erosion of adjacent cortex, exposes the needle tip, prevents the needle from shattering and avoids further articular damage. There was an uneventful 15 months follow up. This case highlights the fact that bone biopsy procedure mandates correct technique and supervision and as far as possible a disposable pre-sterilized bone biopsy needle should be used.

The optimization of drilling operations is an ongoing necessity since the major proportion of the terrestrial hydrocarbon reservoirs has been exhausted. Furthermore, there is a growing tendency among the space exploration agencies to drill the subsurface formations of the remote planets, such as the Moon and Mars. To optimize the drilling efficiency in such complicated conditions, the mechanical specific energy (MSE) must be efficiently reduced. The available MSE models incorporate the different parameters related to the surface rig, drill bit, and the underlying rocks to estimate the MSE values. In this research, the current status of those MSE models is assessed, and their relevant assumptions, limitations, applications, and pros and cons are profoundly argued. From the current scrutiny, it was deduced that the available MSE models require more geomechanical parameters to be included in their formulations. Furthermore, the use of artificial intelligence (AI) techniques was identified as an effective solution to incorporate such geomechanical parameters in the MSE models. Moreover, the establishment of suitable MSE models for off-Earth drilling applications was also revealed to be very urgent and essential. The performed analyses together with the comparative assessments are contributing factors for the modification and establishment of future MSE models.

An IML-Resi PD-400 drilling tool with two types of spade drill bits (IML System GmbH, Wiesloch, Germany) was used to study the influence of the drilling direction in relation to wood grain orientation on drilling resistance (DR) and feeding resistance (FR) measurements. The drilling tests were performed on Scots pine, European beech, English oak and Silver poplar conditioned in a standard climate. The differences in DR between radial and tangential drilling direction were negligibly small or minor for both drill bit types. In contrast, the difference between longitudinal and tangential drilling direction was more pronounced but differed between wood species and drill bit types. FR was the most sensitive parameter to changes in the wood grain orientation when using a drill bit with a single major cutting edge. The mean FR decreased by approximately 27% for Scots pine, 33% for Beech, 37% for Oak and 40% for Poplar when changing the drilling direction from longitudinal to tangential. It was concluded that the drilling direction between longitudinal and transversal drillings needs to be considered for the prediction of wood properties based on DR measurements. Potential applications of drill bits with a single major cutting edge can be the object of further studies. [ABSTRACT FROM AUTHOR]

Company ‘’INGRAM’’ p.l.c. Srebrenik exploits the stone aggregate – limestone, with the technology of drilling and blasting on limestone quarry “Duboki potok”. There are thre drilling rigs of the company “Atlas Copco” used to make blastholes, namely: ROC 301, ROC 406 and ROC F6. This paper analyzes the conditions of drill bits “exploitation”, the lifetime of the drill bits, or the causes of excessive wear of the drill carbides, as well as their loss from the bearing (groove) in which they are installed, with partial damage to the bits matrix face. The influence of basic drilling parameters and the influence of physical and mechanical properties of the working environment on the penetration rate, i.e. on the wear and loss of cutting structures (carbides) of the drill bits on the AC ROC F6 drilling rig, was analyzed, with the aim of finding and defining their interconnection. problems in future works on the construction of blastholes on this limestone deposit. [ABSTRACT FROM AUTHOR]

Background: When a pilot hole is made prior to a screw's insertion into bone, the same drill bit is used irrespective of the bone quality. However, osteoporotic bone is fragile and this may affect the hole diameter, which is of particular concern in cancellous bone. In this study, the relationship between bone density and drill-hole diameter was investigated assuming a pre-drilling process in screw-only osteosynthesis in the metaphysis and epiphysis., Methods: Two types of drill bit (triple-flute [T] and quadruple-flute [Q]) with different shapes and diameters were prepared: type T bits with 3.5 mm and 4.4 mm diameters, and type Q bits with 3.5 mm and 4.2 mm diameters. Drilling was performed manually in simulated bones with four densities: 5, 10, 15, and 20 pounds per cubic foot. We measured the hole diameters with a coordinate measuring machine and analyzed the relationship between the drill-hole diameters and the densities of the simulated bones. We then compared the screw pull-out strength between the two 3.5-diameter drill bits., Results: In all cases, the diameters of the drill holes were larger than those of the drill bits. The relationship between the drill-hole diameters and the bone densities was a negative linear correlation. Enlarging the hole diameter decreased the screw pull-out strength., Conclusions: For cannulated drill bits of 3.5, 4.2 and 4.4 mm diameter, the diameter of the drill hole in cancellous bone obtained by the manual drilling technique tends to be larger in low-density (e.g., osteoporotic) compared to high-density (e.g., healthy) bone., Competing Interests: Declaration of competing interest This research was not supported by any specific grant from funding agencies in the public, commercial, or not-for-profit sectors., (Copyright © 2024 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

An IML-RESI PD 400 drilling tool and a standard spade drill bit (IML System GmbH, Wiesloch, Germany) were used to study the combined effect of wood moisture content (MC), drill bit rotational speed and feed rate on drilling resistance (DR) and feeding force (FF). Tests were made with Norway spruce (Picea abies (L.) Karst.) conditioned in a normal climate (20°C/65% RH), at 20°C/95% RH, vacuum-pressure impregnated in water, and oven-dried. Rotational speeds and feed rates had an impact on feed rate per cutting edge for the major cutting edge of the drill bit which was used for correlation with DR and FF for various MC. Impact of MC on DR and FF depended on rotational speeds and feed rates of the drill bit. For feed rates per cutting edge less than 0.09 mm, DR was higher for water saturated (WS) specimens. Negligible differences between DR for various MC were found for feed rates per cutting edge between 0.09 and 0.15 mm. DR was higher at low MC for feed rates per cutting edge which were higher than 0.15 mm. FF extremely increased in conditioned (20°C/95% RH) and WS specimens at feed rates per cutting edge less than 0.1 mm. [ABSTRACT FROM AUTHOR]

Background/Aim: Many cases of bone damage are due to trauma and metabolic diseases. This study aimed to evaluate bone regeneration into a porous hydroxyapatite (HA) scaffold using dexamethasone (DM)-loaded polymeric microspheres. Materials and Methods: Four adult dogs were used to evaluate the in vivo performance of DM-loaded microspheres immobilized on the surfaces of porous HA scaffolds. Two 5-mm drill holes were created in both the left and right femurs of each dog. The experimental groups included a control group (drill holes filled with HA scaffold alone), a DM 20 group (holes filled with DM-loaded HA scaffold with 20 mg DM per scaffold), and a DM 100 group (hole filled with DM-loaded HA scaffold with 100 mg DM per scaffold). Resulting bone volume percentages and bone mineral densities were calculated by examing microcomputed tomographic (CT) images. Results: The DMloaded HA scaffold groups showed a gradual periosteal reaction two weeks after insertion of the HA scaffold into the femoral drill holes. Four weeks after HA scaffold insertion, the periosteal reaction in the femoral drill holes became denser. Eight weeks after insertion of DM-loaded HA scaffolds, clear images of the scaffold were observed in micro-CT images of the femoral drill hole. The DM 100 group had better bone healing tendencies (bone mineral density, bone mass, trabecular volume, bone surface, and trabecular thickness) than the DM 20 group. Conclusion: DM-loaded HA scaffolds are suitable platforms for distributing bioactive molecules during osteogenesis in femoral drill holes. [ABSTRACT FROM AUTHOR]

A new type of ice core drill bit, designed with a vane swirler, was developed for ice core drilling with air reverse circulation. An orthogonal experimental design method was employed to investigate the effects of the swirler structure parameters on the reverse circulation performance of the drill bit including helical angle, number of blades, blade length and blade central angle, etc. The entrainment ratio was used to evaluate the reverse circulation effectiveness of the drill bit. The results show that the helical angle is the dominant factor regardless of whether or not the flushing nozzles are part of the design of the drill bit. The number of blades is the least important factor for the drill bit designed with the flushing nozzles (referred to as drill bit I), while the outlet area of the swirling slot is the least influential factor for the drill bit without flushing nozzles (referred to as drill bit П). In addition, the appearance of the ice core has a certain effect on the air reverse circulation for both drill bits. Within the ranges of this study, the optimal structure of the drill bit was determined based on the range analysis of the orthogonal design. [ABSTRACT FROM AUTHOR]

Drilling volumes should be increased in order to increase hydrocarbon production, but this is impossible without the usage of high-quality drilling tools made of modern structural materials. The study has to analyze the design, technological and operational methods to increase the performance of drilling tools made of various materials and has highlighted prospects of technological method applications. The scientific novelty of the study consists in the development of a new analytical model of PDC drill bit–well interaction. The developed model takes into account the drill bit manufacturing errors in the form of bit body–nipple axes misalignment on the drill bit strength. This result makes it possible to determine the permissible manufacturing errors to provide safe operation of the drill bit. It is established that there is an additional transverse force that presses the drill bit to the well wall in the rock due to manufacturing errors. It is determined that the magnitude of this clamping force can be significant. The material effect has been analyzed on additional clamping force. It is established that geometric imperfection of the drill bit causes the minimal effect for the elastic system of the pipe string, which includes a calibrator and is composed of drill pipes based on composite carbon fiber material, and the maximal effect—for steel drill pipes. Polycrystalline diamond compact (PDC) drill bit and well wall contact interaction during operation in non-standard mode is considered. Non-standard stresses are determined, and the strength of the blades is estimated for different values of drilling bit manufacturing error.