Ultrasonic Drilling Research Articles

Development of a rotary-percussive ultrasonic drill using a bolt-clamped type piezoelectric actuator

Obtaining rock samples by drilling is an important method of asteroid detection. Due to the strict restrictions on the weight, volume, and weight on bit, conventional drilling devices are difficult to meet the requirements of drilling on an asteroid that has a weak gravitational field. This article proposed a rotary-percussive ultrasonic drill using a bonded-type piezoelectric actuator that can output harmonic vibration and elliptical trajectories simultaneously. The configuration and operation principle of the RPUD is presented and analyzed. Mode shape of the actuator and motions of the driving tips are verified by modal analysis and transient analysis, separately. Ultimately, a prototype of the RPUD is fabricated and experimentally investigated for its output characteristic and drilling performance. The test results indicate that the developed actuator can achieve the maximum no-load rotary speed of 119.2 r/min when the excitation frequency is 17.79 kHz. Furthermore, the maximum torque is 35 mNm, and the corresponding driving speed is about 20 r/min. The maximum drilling rate of the prototype to the sandstone is 7 mm per minute under a weight on bit of 5 N. The experimental results confirm that the proposed RPUD is feasible to drill rocks under a low weight on bit, which has the potential to obtain rock samples on an asteroid.

Simulation and experimental investigations of ultrasonic-assisted drilling with Micro-PDC bit

Ultrasonic-assisted drilling (UAD) technology is a new drilling technology, which combines polycrystalline diamond compact (PDC) bits and performs better than conventional PDC drilling in improving the rock-breaking efficiency during deep hard formations. In this study, a series of simulations and laboratory tests were conducted to explore the dynamic rock-breaking mechanism of UAD with a PDC bit and the influence of different input parameters on the force and energy distribution. First, the UAD process was analyzed using a simplified drilling system model, and the relationship between the axial and tangential forces was investigated using a single PDC cutter cutting model. Then, a finite element analysis model that considers rock heterogeneity was used for the analysis. The drilling process, element damage situation, and broken form of the borehole bottom of conventional drilling (CD) and UAD were compared, and the impact of amplitude, frequency, and rotary speed on the weight on bit (WOB), torque, cutting force, and energy consumption were evaluated. Finally, laboratory experiments on PDC micro-drilling for different drilling conditions were conducted to verify the effectiveness of UAD. The results indicate that during rock-breaking using UAD, the PDC cutter periodically penetrated and broke away from the rock with ultra-high frequency, causing a large amount of damage to the rock. The frequency and amplitude significantly influenced the UAD: when the vibration frequency was between 25 and 35 kHz, the force state of the PDC cutter greatly improved compared with that of CD, and the effect of ultrasonic load reached the maximum at 33 kHz; when the amplitude was between 10 and 50 μm, WOB and torque decreased significantly and the effect of ultrasonic load improved with increase in amplitude, but the rotary speed had little effect on the torque and WOB of UAD. During the laboratory experiments, the drilling efficiency and rate of penetration (ROP) improved on using UAD. When the WOB was 100–200 N and the rotary speed was 300–400 rpm, the efficiency of ultrasonic rotary drilling to improve the ROP increased by 14.7–23.4%.

A novel model of vibration plowing effect for longitudinal ultrasonic vibration-assisted drilling

A novel model of the vibration plowing effect (VPE) is proposed for the first time to reveal hitherto not well-understood ultrasonic cutting mechanics and provide a theoretical basis for controlling the tool wear and machining quality of longitudinal ultrasonic vibration-assisted drilling (LUAD). The new model includes a condition model to judge the occurrence of the VPE on the whole flank of the drill and a volume model to calculate the vibration plowing force caused by the VPE of LUAD. For one thing, a condition model is proposed to distinguish the plowing effect of conventional machining and the VPE of LUAD by comprehensively analyzing the relationship between the clearance angle of the main cutting edge and the drill's path. For another, an analytical model of the vibration plowing volume (VPV) of LUAD is derived by integrating the plowing volume of the main cutting-edge element to improve the tool wear and machining quality. Finally, a series of comparative experiments between conventional drilling (CD) and LUAD is carried out. The validity of the proposed VPE's condition model and the VPV's analytical model is verified by the chip's micromorphology and the specific plowing force of the workpiece, respectively. The experimental results show that the fine and regular textures caused by the VPE can be observed on the chip surface and side micromorphology of LUAD. However, the coarse and irregular textures are displayed in CD, which shows that the proposed conditional model is adequate. Moreover, it is calculated by the deduced VPV's analytical model that when the ultrasonic amplitude is 3.8 and 8.3 μm, the average value of the specific plowing force of Al 6061-T6 determined in this paper is 1.399 × 105 N/mm3 and 1.274 × 105 N/mm3, respectively. These results agree with the value reported in other literature, that is 1.31 × 105 N/mm3, which proves the validity of the proposed model of the VPV. The validated analysis model is then used to conduct predictive analysis on the VPE and vibration plowing force of LUAD under a series of process parameters. The above research results clarify the mechanism of vibration plowing under ultrasonic action and provide a theoretical basis for controlling the tool wear and machining quality of LUAD.

Theoretical substantiation of low-frequency shock-contact impact as a way to increase the efficiency of ultrasonic drilling of extraterrestrial soil

A physical and mathematical model of ultrasonic destruction and deformation of solid soil has been developed, taking into account the presence of additional influences (low-frequency impact, rotational). The numerical implementation of the model is carried out in the form of a computer program for calculating the process of deformation and destruction of the soil. The presented results of calculations proved the possibility of additionally increasing the efficiency of ultrasonic drilling by more than 2.5 times due to the imposition of low-frequency shock-contact action.

Dorsal preservation rhinoplasty with an ultrasonic drill system in Republic of Korea: a case report

Dorsal preservation rhinoplasty with an ultrasonic drill system in Republic of Korea: a case report

Experimental research on new hole-making method assisted with asynchronous mixed frequency vibration in TiBw/TC4 composites

With the gradual promotion and the application of difficult-to-machine materials such as titanium matrix composites in the aerospace field, high-quality hole-making technology has become a major demand in aviation manufacturing. In order to improve the hole-making quality of TiBw/TC4 composites, asynchronous mixed frequency vibration-assisted hole-making (AMFVAHM) method is proposed. The process consists of two steps: ultrasonic vibration-assisted drilling (UVAD) base hole and low-frequency torsional vibration-assisted helical milling (LFTVAHM) target hole. Based on this process, the cutting trajectory modeling is established, and the hole-making experiment on TiBw/TC4 composites is conducted. The experimental data show that during the hole expansion stage, the maximum XY-plane average milling force decreases by 30.96% and the maximum axial average milling force decreases by 24.49% compared with conventional helical milling (HM) when the torsional vibration frequency and the milling frequency are the same in LFTVAHM. The hole-making experiment shows that AMFVAHM can reduce the chip size, tool wear, and some other defects such as entrance/exit burrs, scratches, and fractures of the hole wall. Comparing with HM and UVAD, the verticality of hole wall increases by 71.43% and 86.21%, the inlet damage decreases by 27.98% and 31.60%, the outlet damage decreases by 2.80% and 14.47%, the hole wall roughness (Ra) decreases by 36.29% and 63.43%, and the maximum white layer thickness decreases by 19.99% and 67.66%. Meanwhile, AMFVAHM process not only reduces the cutting force and cutting temperature but also improves the hole-making quality due to the fretting friction effect of LFTVAHM in secondary hole expansion, which meets the need for high-quality hole-making of difficult-to-machine materials in practical engineering applications.

Ironing effect on surface integrity and fatigue behavior during ultrasonic peening drilling of Ti-6Al-4V

Imposing compressive residual stress field around a fastening hole serves as a universal method to enhance the hole fatigue strength in the aircraft assembly filed. Ultrasonic Peening Drilling (UPD) is a recently proposed hybrid hole making process, which can achieve an integration of strengthening and precision-machining with a one-shot-drilling operation. Due to the ironing effect of tool flank surface, UPD introduces large compressive residual stress filed in hole subsurface. In order to reveal the strengthening mechanism of UPD, the influence of ultrasonic vibration and tool dynamic relief angle on ironing coverage rate and its corresponding effect on surface integrity in UPD were analyzed. The experiments were conducted to verify the influence of ironing effect on surface integrity and fatigue behavior of Ti-6Al-4V hole in UPD. The results indicate that the specimen features smaller surface roughness, higher micro-hardness, plastic deformation degree and circumferential compress residual stress under higher ironing coverage rate. The fatigue life increases with the raise of ironing coverage rate, and the fatigue source site in UPD shifts from surface to subsurface comparing with that without vibration assistance. The results demonstrates that a better strengthening effect can be obtained by reasonably controlling the ironing coverage rate in UPD.

Prediction of temperature elevation in rotary ultrasonic bone drilling using machine learning models: An in-vitro experimental study.

Bone drilling is frequently used during orthopaedic surgeries to treat the fractured part of the bone. A major concern for surgeons is the increase in temperature during real-time orthopaedic bone drilling. The temperature elevation at the bone-tool interface may cause permanent death of regenerative soft tissues and cause thermal osteonecrosis. A robust predictive machine-learning model is suggested in this in-vitro research for monitoring temperature rise during surgery. The objective of the present work is to introduce different machine learning algorithms for predicting temperature elevations in rotary ultrasonic bone drilling. Different machine-learning models were compared with the standard response surface methodology. The performance and accuracy of different predictive models were compared at different error metrics. It was witnessed that support vector machines performed the best for predicting the change in temperature in comparison to other predictive models. Moreover, the error metrics for statistical response surface methodology analysis were comparatively higher than the machine learning algorithms. By using machine learning models, it is possible to predict temperature rise during bone drilling.

Experimental study on longitudinal-torsional ultrasonic vibration drilling of carbon fiber–reinforced plastics/titanium alloy stacks

Carbon fiber–reinforced plastics (CFRP)/titanium alloy (Ti) stacks are extensively applied in the aerospace industry due to their excellent mechanical properties. However, their poor machinability poses great challenges. In this study, longitudinal-torsional ultrasonic vibration drilling (LT-UVD) is innovatively introduced to improve the quality of CFRP/Ti drilling. First, the separation mode of LT-UVD is analyzed by kinematic equations. Then, an experimental platform is built based on the LT-UVD vibration actuator to perform CFRP/Ti drilling experiments. The thrust force, interface temperature, hole wall quality, hole defects, Ti chip morphologies, and tool wear in LT-UVD are experimentally compared against conventional drilling (CD) and longitudinal ultrasonic vibration drilling (L-UVD). The experimental results show that, compared with CD and L-UVD, the thrust force of CFRP in LT-UVD decreases by 20.36–40.55% and 2.04–14.61%, while the thrust force of Ti decreases by 19.08–24.83% and 1.95–9.34%. Moreover, a relatively low maximum interface temperature is achieved in LT-UVD. In addition, the hole size accuracy, surface roughness for the hole’s inner surface, and delamination factor are improved in LT-UVD. Fiber pullout defects, chip-breaking performance, and tool wear of CFRP are improved due to torsional vibration in LT-UVD. Finally, according to the high-speed camera, damage forms of the interface area are different when drilling CFRP/Ti stacks with various drilling sequences.

Investigation on natural fiber reinforced polymer matrix composite

Natural fiber reinforced polymer composite is playing a vital role in advanced manufacturing process. The present investigation deals with ultrasonic drilling on the synthesized gelatin natural fiber composite. Lapox and screw pine fiber is considered as the reinforced matrix to the gelatin polymer. Hardness, tensile strength and impact strength is evaluated in the composite. Power rating, slurry concentration and grit size is used to evaluate the rate of metal removal of the composite. Taguchi approach is analyzed to optimize the rate of metal removal. The mean of SN ratio plot is used to study the optimal solution and correlation between the process factors.

Experimental Investigation of Thrust Force in the Drilling of Titanium Alloy Using Different Machining Techniques

Titanium alloy is a kind of hard-to-cut material widely used in aerospace, military and medical fields, and mechanical drilling is the primary technique used for hole-making in titanium alloy materials. The drilling force is an inevitable concomitant phenomenon in the drilling process and thrust force is its most important component. During the drilling of titanium alloy, it is crucial to understand the fundamental characteristics and changing rules of thrust force for optimizing process parameters, improving machining quality and predicting tool failure. In this paper, four different techniques, such as direct drilling (DD), ultrasonic vibration drilling (UVD), peck drilling (PD) and ultrasonic vibration peck drilling (UVPD), were used to drill small holes into Ti-6Al-4V titanium alloy, the thrust force was measured and its mean, maximum and peak-to-valley value were acquired from the time-domain waveform. Then the time-domain and frequency-domain characteristics of thrust force under the four techniques were compared, and the changing rules of thrust force with vibration amplitudes during UVD and UVPD were investigated. The results showed that, when compared to DD, UVD decreased the mean thrust force Famean by about 18.6%, and the force reduction effect was more significant as the amplitude increased. The variable velocity cutting characteristics and the antifriction effect of UVD were the primary reasons for the reduction of Famean. The pecking motion and ultrasonic vibration had a synergistic effect on reducing thrust force; UVPD could simultaneously reduce the mean thrust force Famean and maximum thrust force Famax. When the amplitude A was chosen within the range of 2–3 μm, Famax and Famean were reduced by approximately 37% and 40% in comparison to DD.

Defect suppression mechanism of ultrasonic vibration-assisted drilling carbon fiber/bismaleimide composite

Ultrasonic vibration-assisted drilling (UVAD) has recently been successfully applied in the drilling of carbon fiber reinforced polymer/plastic (CFRP) due to its high reliability. Multiple defects have been observed in the CFRP drilling process which negatively affects the quality of the hole. The carbon fiber/bismaleimide (BMI) composites is an advanced kind of CFRPs with greater strength and heat resistance, having been rapidly applied in lightweight and high temperature resistant structures in the aerospace field. To suppress the defect during the drilling of carbon fiber/BMI composites, it is necessary to comprehensively understand the defect formation and suppression mechanism at different positions. In this study, the defects formation in both conventional drilling (CD) and UVAD were observed and analyzed. The variation trend in the defect factor and thrust force with the spindle speed and feed rate were acquired. The results revealed that the UVAD could significantly enhance the hole’s quality with no delamination and burr. Meanwhile, the defect suppression mechanism and thrust force in UVAD were analyzed and verified, where the method of rod chip removal affected the exit defect formation. In summary, UVAD can be considered a promising and competitive technique for drilling carbon fiber/BMI composites.

Optimal Design of Ultrasonic Horn for Ultrasonic Drilling Processing of Ceramic Material

Optimal Design of Ultrasonic Horn for Ultrasonic Drilling Processing of Ceramic Material

Concept and electromechanical-coupling modeling of a torsional vibration excitation method

The sandwiched type torsional piezoelectric actuators have widely been employed in the fields of ultrasonic cutting, ultrasonic drilling, ultrasonic welding, ultrasonic wire drawing, ultrasonic spraying, and microdroplet generation, due to their unique vibration form. However, the circular piezoelectric ceramic plate polarized in the circumferential direction holds a complicated manufacturing process, a long processing period, and a high price. It can only be used for the excitation of the torsional vibration of circular rods, and cannot be used for square cross-section beams, severely restricting its applications. In order to solve the above problems, a novel excitation method is proposed for generating torsional vibration in the square cross-section beam in this study, which uses the d15 vibration mode of rectangular piezoelectric ceramic plates to produce the torsional vibration, and a novel transfer matrix model of square torsional piezoelectric element is created. Then a case study is conducted in this paper to confirm the proposed excitation method and the developed model, in which two novel sandwiched type torsional piezoelectric actuators are designed. Moreover, electromechanical coupling models of these two torsional piezoelectric actuators are developed using the transfer matrix method, in order to reveal their dynamics behaviors. Finally, the finite element method and the experimental investigations are adopted to analyze and test the frequency response characteristics and vibration shapes of the proposed piezoelectric actuators. Both simulation analysis and experimental tests verify the effectiveness of the proposed excitation method and the correctness of the developed electromechanical coupling dynamic models. The proposed excitation method provides a new idea for the design of sandwiched type torsional piezoelectric actuators, and the developed theoretical model lays a theoretical foundation for the further research of torsional piezoelectric actuators.

Elucidation of Drilling Behavior on Workpiece Superimposed with Ultrasonic Vibration

This study quantitatively and theoretically clarifies the machining characteristics of the chisel engagement and the cutting-edge wear behavior in drilling in a workpiece superimposed with ultrasonic vibration. The machining phenomenon of drilling by this method considers being the same as drilling by ultrasonic vibration spindle from the viewpoint of the relative motion of the cutting edge and workpiece. However, the details have not been clarified yet. The chisel engagement behavior experiment at the initial stage of the drilling and cutting-edge wear experiment were carried out in this study. The chisel engagement behavior experiment revealed lower axial relative velocity results in a minor effect. In the cutting-edge life experiment, when the cutting fluid and the supply method were changed, the minimal oil with mist supply showed the same result as water-soluble with jet supply without breaking the drill. However, considerable wear was generated at the cutting edge in the initial drilling stage. When suitable ultrasonic vibration-assisted drilling was applied, initial wear decreased by 40% but could not be suppressed entirely. As a result of theoretical elucidation on this initial wear, it was proven that the flank face of the cutting edge contacted the workpiece when critical amplitude was exceeded. In the experiment to prove the validity of this theory, the initial wear occurred when the critical amplitude was exceeded. The cutting-edge wears increased in proportion to the working relief angle.

Development of a generator for percussive ultrasonic drills used in asteroid exploration based on impedance characteristics analysis

Percussive ultrasonic drills participate in asteroid exploration missions. Since space environments are complex and working loads vary dramatically, it is necessary to design a drive that better matches the percussive ultrasonic drill to make it achieve high-speed drilling with low power consumption. Impedance characteristics under different load conditions and the load varying in one drilling cycle are investigated based on analyzing the working principle of the percussive ultrasonic drill. An ultrasonic drill driver with automatic scanning resonant frequency and digital phase-locked loop frequency tracking control is designed according to the load characteristics. Series capacitance impedance matching ultrasonic drills is experimentally studied. Vibration amplitude and impedance characteristics of the ultrasonic drill driven by the designed driver are measured to evaluate the frequency tracking ability and the impedance matching. Finally, ultrasonic drilling experiments are conducted in room, low, and high temperature environments to investigate the driving performance. Under room temperature and 5 N drilling pressure, the speed of ultrasonic drilling into soft sandstone is 52 mm/min, and the power consumption is less than 70 W. The experimental results indicate that the designed driver can drive the percussive ultrasonic drill to achieve stable and high-speed drilling with low power consumption and low drilling pressure.

Prediction of surface roughness and cutting force induced during rotary ultrasonic bone drilling via statistical and machine learning algorithms

The ultrasonic-assisted drilling of bone is gaining significant attention in orthopedic research and clinical applications due to the advantage of reducing thermal necrosis, cutting force, and microcracks. Mechanical and surface morphological damage due to cutting force and surface roughness rise during bone drilling may result in implant failure during osteosynthesis. It is difficult to predict and measure cutting force and surface irregularities during real-time medical orthopedic surgery. Therefore, the present work uses the application of different machine learning models to predict cutting force and surface roughness induced during bone drilling. The predictive results of machine learning models were compared with statistical analysis. During the study, rotary ultrasonic drilling is performed on the pig femur bone. The surface roughness and cutting forces are monitored using a surface roughness tester and a dynamometer respectively. Predictive models were developed by drilling parameters such as spindle rotational speed, abrasive girt size, and feed rate. Various machine learning algorithms such as ridge regression, lasso regression, support vector regression, multi-linear regression, and artificial neural networks were leveraged and compared at different error metrics to provide a robust predictive model. It was observed that ridge regression has the least error metrics compared to other machine learning algorithms during surface roughness prediction. Moreover, the most accurate model for predicting cutting force was support vector regression. The error metrics for statistical analysis were comparatively higher than the machine learning algorithms. Therefore, machine-learning algorithms are preferable for adequate prediction of surface roughness and cutting force induced during bone drilling compared to statistical analysis.

Study on the mechanism of AL2024-T351/Ti-6Al-4V laminated materials by ultrasonic vibration drilling

Study on the mechanism of AL2024-T351/Ti-6Al-4V laminated materials by ultrasonic vibration drilling

Tool wear prediction in ultrasonic vibration-assisted drilling of CFRP: A hybrid data-driven physics model-based framework

Accurate tool wear prediction is the key to evaluating tool usability and ensuring drilling quality. Recently, fusion prediction methods have attracted great attentions. However, no similar work has been reported yet in ultrasonic vibration-assisted drilling (UVAD) of carbon fiber reinforced polymer (CFRP). To fill this gap, a hybrid data-driven physics model-based framework for predicting tool wear is proposed. The physics model builds a mathematical description of the tool wear degradation process. The data-driven model predicts tool wear based on multilayer perceptron (MLP). The fusion method fuses the results of both models based on particle filter to obtain the final tool wear. Results indicate that the hybrid model performs better than any of individual models, with the lowest prediction errors.

Influence of cutting force on temperature, microcracks and chip morphology during rotary ultrasonic bone drilling: An in-vitro study

Influence of cutting force on temperature, microcracks and chip morphology during rotary ultrasonic bone drilling: An in-vitro study