Hydraulic Drills Research Articles

Novel Ensemble Domain Adaptation Methodology for Enhanced Multi-class Fault Diagnosis of Highly-Connected Fleet of Assets

This paper proposes a novel methodology for enhancing multi-class classification accuracy in fault diagnosis problems among domains with highly-connected fleets of assets using time series data. The approach involves appending specially tailored models to an initial model and incorporating domain adaptation techniques to account for domain variations. The methodology is demonstrated through a case study on fault diagnosis of a fleet of hydraulic rock drills, which presents challenges due to variations in sensor data between different fault classes and individual machines. Results show significant improvements in classification accuracy, both in validation and testing, upon employing ensemble models and applying domain adaptation. While the study is limited to one case study, it lays the groundwork for exploring the applicability of the proposed methodology in other contexts.

Realization of shorter substitutes for a percussive rock drill hammer by periodic redistribution of its mass and compliance

In percussive drilling of rock, use is made of high-amplitude short-duration force pulses generated through impacts of a hammer on a drill bit or a drill rod assembly. The mass of the hammer is crucial for the impact velocity and the impact frequency, while its length and variation of characteristic impedance control the duration and shape of the force pulses. High efficiency of conversion of kinetic impact energy to work results if the force pulses have suitable shapes and durations. Commonly, hammers of hydraulic rock drills are nearly uniform and generate nearly rectangular force pulses admitting high efficiencies. When space is constrained, short hammers are advantageous as they allow short rock drills. Here, therefore, shorter substitutes for uniform original hammers are sought. They should have the same mass as the original hammer, be shorter than the original hammer, and generate approximately the same impact force history as the original hammer. A method based on 1D theory is developed for realization of substitute hammers with axially periodic characteristic impedance. Impact force histories generated by such hammers agree well with that generated by a uniform original hammer in a 1D context, and also in a 3D context if 3D effects are small enough. Also, for bit-rock interaction conditions from soft to hard, the efficiencies obtained by use of substitute hammers agree well with that obtained by use of the original hammer.

A Hybrid Approach Combining Data-Driven and Signal-Processing-Based Methods for Fault Diagnosis of a Hydraulic Rock Drill

This study presents a novel method for fault diagnosis of a hydrostatic rock drill. Hydraulic rock drills suffer from both domain discrepancy issues that arise due to their harsh working environment and indivisible difference. As a result, fault diagnosis is very challenging. To overcome these problems, we propose a novel diagnosis method that combines both data-driven and signal-process-based methods. In the proposed approach, data-driven methods are employed for overall fault classification, using domain adaptation, metric learning, and pseudo-label-based deep learning methods. Next, a signal-process-based method is used to diagnose the specific fault by generating a reference signal. Using the combined approach, the fault-diagnosis performance was 100%; the proposed method was able to perform well even in cases with domain discrepancy.

Hydraulic Rock Drill Fault Classification Using X−Vectors

Hydraulic rock drills are widely used in drilling, mining, construction, and engineering applications. They typically operate in harsh environments with high humidity, large temperature differences, and vibration. Under the influence of environmental noise and operational patterns, the distributions of data collected by sensors for different operators and equipment differ significantly, which leads to difficulty in fault classification for hydraulic rock drills. Therefore, an intelligent and robust fault classification method is highly desired. In this paper, we propose a fault classification technique for hydraulic rock drills based on deep learning. First, considering the strong robustness of x−vectors to the features extracted from the time series, we employ an end−to−end fault classification model based on x−vectors to realize the joint optimization of feature extraction and classification. Second, the overlapping data clipping method is applied during the training process, which further improves the robustness of our model. Finally, the focal loss is used to focus on difficult samples, which improves their classification accuracy. The proposed method obtains an accuracy of 99.92%, demonstrating its potential for hydraulic rock drill fault classification.

Pneumatic Underwater Coral-Coring Drill

Abstract To extract meter-length, large-diameter cores from live massive corals on shallow reefs we developed a versatile underwater pneumatic drill driven by a portable gasoline-powered air compressor carried onboard a small boat. This drill was used to obtain intact cores 8.0 cm in diameter and 0.5‐1.5 m long from Guam's coastal waters. Advantages of this pneumatic drill over standard hydraulic drills include (1) lower cost; (2) easier portability; (3) more stable, safer, and faster drilling; and (4) elimination of the need to carry and use hydraulic fluid on the coral reef. The pivotal innovation in the application of pneumatic technology was use of an air motor rather than a conventional handheld pneumatic drill. Another significant innovation was employment of a pneumatic water pump to provide a continuous flow that purges debris from the borehole and the cutting edge of the diamond drill bit. This drill can provide paleo-climate researchers and others interested in retrieving high-quality coral core samples with a reliable, economical, easy to operate, safe, and environmentally friendly alternative to more expensive and cumbersome hydraulic drills.

Fault Identification in Hydraulic Rock Drills from Indirect Measurement During Operation

This work presents a method for on-line condition monitoring of a hydraulic rock drill, though some of the findings can likely be applied in other applications. A fundamental difficulty for the rock drill application is discussed, namely the similarity between frequencies of internal standing waves and rock drill operation. This results in unpredictable pressure oscillations and superposition, which makes synchronization between measurement and model difficult. To overcome this, a data driven approach is proposed. The number and types of sensors are restricted due to harsh environmental conditions, and only operational data is available. Some faults are shown to be detectable using hand-crafted engineering features, with a direct physical connection to the fault of interest. Such features are easily interpreted and are shown to be robust against disturbances. Other faults are detected by classifying measured signals against a known reference. Dynamic Time Warping is shown to be an efficient way to measure similarity for cyclic signals with stochastic elements from disturbances, wave propagation and different durations, and also for cases with very small differences in measured pressure signals. Together, the two methods enables a step towards condition monitoring of a rock drill, robustly detecting very small changes in behaviour using a minimum amount of sensors.

Design on Key Parameters of Double Damper System for Hydraulic Rock Drill

The lack of research on the double damper system seriously restricted the impact power’s increase of hydraulic rock drills. The structure and working principle of the double damper system are described. The key parameters such as the unloading damping pressure, damping flow, equilibrium position of the damping piston, and double damper clearance are designed. At last, the design method is applied to the YYG170 hydraulic rock drill. Double damper system’s advantages of high efficiency and fast response are verified by simulation.

Research on Shallow Stress Variation before and after the 2011Japan Earthquake in Bohai Strait and Its Adjacent Area

To identify the geostress adjustment process of Japanese earthquake in Bohai Strait and its surrounding area, based on the data of 10 shallow hydraulic fracturing drills in the axis of the channel acquired from 2012 to 2014, the dispersed point charts and regression formulas of each parameter with depth were established and calculated. The results showed that between 2010 and 2014, the horizontal differential stress first decreased and then increased, and the direction of stress first rotated clockwise and then counter-clockwise. Therefore, coseismic and postseismic displacement triggered by Japanese earthquake caused shallow extensional effect which lasted from 2011 to 2012 in research area, and shallow stress didn’t return to the original level until 2013. During the period of shallow stress reduction, the fault zone of seismic hazard was reduced as the compressive strain energy was released, while during the period of sustained stability after stress recovery the NWW fault zone had the maximum seismic hazard than NNE. The results were of great significance for research on shallow stress accumulation caused by earthquake, fault activity and the construction of tunnel in Bohai Strait and its surrounding area.

Cavitation erosion of the damping piston in double damping system of hydraulic rock drill and its influencing factors

The fast response property of double damping system is beneficial to improve damping characteristics. However, the intense pressure fluctuation in damping chambers often leads to the cavitation erosion of damping piston and seriously affects the normal use of seal and rock drill. The coupling model including the damping piston, damping valve, damping accumulator and connecting pipelines was established considering the structural feature and dynamic characteristics of damping system. The cavitation erosion mechanism was revealed by the simulation results. Analysis suggested that the pipeline damping and oil flow velocity between the primary and secondary damping chamber were the critical influencing factors for the cavitation erosion. The influence on system cavitation of damping valve structure and connecting pipeline types was discussed, and the reasonable range of matching parameters was given. Pressure curves in the primary, secondary damping chamber and noise spectra of cavitation were obtained by the field rock drilling test. The simulation and experimental results had consistency. The system cavitation was detected by the high-frequency pulsating pressure signal and its power spectral density analysis. This detection method provides a new approach for studying the cavitation behavior of hydraulic rock drills.

Improvement of shock system of hydraulic drill to increase drilling intensification

The article deals with features of drilling and blasting operations with the use of hydraulic drills prevailing in the amount of use as drilling heads on drilling (mining) equipment. The device and the operating principle of hydraulic drills are discussed. In order to increase the intensification of drilling, the modernization of hydraulic drills is proposed by using the “shock-worker –striker - shank” shock system, which is characterized by an increase in the transfer coefficient of the shock pulse through the striker, performing high-frequency oscillations («rattling» striker) between the shock-worker and the shank. A graph of the dependences of the parameters of the modernized shock system is given and the conditions for the existence of the «rattling» phenomenon of the striker due to which the drilling productivity is expected to be increased are indicated.

打撃式油圧さく岩機による穿孔過程

Rock drills were developed about two hundred years ago, and hydraulic percussion rock drills are about half-century old. Performance and efficiency of rock drills have been increased by a number of researchers and engineers. Percussion energy was dramatically increased with changing the power source from pneumatic to hydraulic pressures; rods and rod joints were improved to endure the high percussion energy; carbide button bits were developed for hard rock drilling. This paper reviewed the previous studies and future issues on the drilling processes with hydraulic percussion rock drills. Studies on the stress wave propagation in rods and rod joints were based on theoretical and graphical methods and recently on numerical simulation. Studies on the interaction between a button bit and rock included crack propagation in rock, force-penetration relationship during drilling, and bit wear. Studies on the factors affecting drilling efficiency and drilling rate made a transition from simple to precise numerical simulations. Finally, important future issues were presented for the further progress of hydraulic percussion rock drills.

Assessment of rock mass quality using drill monitoring technique for hydraulic ITH drills

Assessment of rock mass quality using drill monitoring technique for hydraulic ITH drills

Assessment of rock mass quality using drill monitoring technique for hydraulic ITH drills

A rock drilling system always responds to variations in the mechanical properties of the penetrated rock mass. Combining the drill response with a detailed understanding of the drill system has the ...

Application on Enhanced Permeability Outburst Prevention Technology of Hydraulic in Rock Cross-Cut Coal Uncovering

According to the practical engineering in Daxing Coal Mine north limb centralized down transportation, the No 13 coal seam rock cross-cut area with high gas pressure and content was serious outburst hazardof. Based on the technical principle and protection outburst mechanism of hydraulic in depressurization and enhanced permeability, the hydraulic drills in rock cross-cut coal uncovering were desinged, and the hydraulic equipment was matched, the measures were constructed, the effect was tested. The results show that the new type integration technology of the integrative hydraulic drilling and reaming obvious increased the plasticity of coal, reduced the stress concentration region of coal seam, improved the permeability of coal, promoted gas release, enhanced the ability of preventing coal and gas breakout, which played an active role in comprehensive outburst controlling, obtain ed a favourable effect in rock cross-cut coal uncovering and has important popularized and applied values.

Contribution to the Numerical Geological Mapping of the Paleocene in the Western Part of Thiès (Senegal)

The locality of Thiès has significant mining and hydrogeological resources that are of major economic interest and necessitates a sustainable management. Most of these resources are contained in the Paleocene. For a better assessment of Paleocene, we elaborated a spatial model using available seismic lines, oil and hydraulic drills. The data were integrated using interpolation, mainly natural neighbor method. The obtained model should make it possible to understand the variation of the lithostratigraphic parameters of the Paleocene. The extraction from the model of the upper and the lower limits showed that the Paleocene is shallow and is outcropping to subout-cropping in the area of Thiès. The model was validated using previously available geological map. Also, a crosscorrelation of the predicted and the observed data showed that the model is accurate.

Multi-body wave analysis of axially elastic rod systems

Axially elastic rods are basic machine elements in hydraulic hammers, pilers, and percussive drills. The problem to analyse the motion history of such mechanisms is a very complex one, because the rods are simultaneously in large-amplitude axial motion superimposed with a small-amplitude elastic wave motion. The wave motion experiences division to reflected and transmitted components at each rod-rod interface depending on the current boundary stiffness. The wave motion in each rod can be computed by finite elements or, alternatively, in space of semidefinite eigenfunctions. The feasibility of these methods in solving wave propagation problems in multi-rod systems with non-linearly behaving rod-rod interfaces has been investigated and evaluated. The object of the experimental case study is a classical Hopkinson split bar apparatus used in experimental analysis of material response to shock pulses. Another example representing a pile hammering system evaluates the computational performance of the proposed approaches in long-termsimulation of a complete work process.

Rock Drills used in South African Mines: a Comparative Study of Noise and Vibration Levels

To compare the noise and vibration levels associated with three hand-held rock drills (pneumatic, hydraulic and electric) currently used in South African mines, and a prototype acoustically shielded self-propelled rock drill. Equivalent A-weighted sound pressure levels were recorded on a geometrical grid, using Rion NL-11 and NL-14 sound level meters. Vibration measurements were conducted on the pneumatic, hydraulic and electric drills in accordance with the ISO5349-1 (2001) international standard on human exposure to hand-transmitted vibration, using a Brupsilonel and Kjaer UA0894 hand adaptor. PCB Piezo accelerometers were used to measure vibration in three orthogonal directions. No vibration measurements were conducted on the self-propelled drill. All four drills emitted noise exceeding 85 dB(A). The pneumatic drill reached levels of up to 114 dB(A), while the shielded self-propelled drill almost complied with the 85 dB(A) 8 h exposure limit. Vibration levels of up to 31 m s(-2) were recorded. These levels greatly exceed recommended and legislated levels. Significant engineering advances will need to be made in the manufacture of rock drills to impact on noise induced hearing loss and hand arm vibration syndrome. Isolating the operator from the drill, as for the self-propelled drill, addresses the problems of both vibration and noise exposure, and is a possible direction for future development.

The Analysis of Vibration Transmitted by Hydraulic Drilling Machines in Underwater Working Conditions

There is little knowledge of the effect of whole-body vibration on a diver working under water. During underwater work the diver is subject to the direct influence of the tool vibration as well as vibration transmitted to his body. The sole aim of this study was hand-arm vibration from hydraulic drills. The test proved that the allowed vibration level was exceeded, especially within the low frequency region from 6.3 Hz up to 125 Hz. These initial results have been applied to the design of a new tool with reduced vibration levels.

Analytical study of percussive energy transfer in hydraulic rock drills : Wu, C Min Sci TechnolV13, N1, July 1991, P57–68

Analytical study of percussive energy transfer in hydraulic rock drills : Wu, C Min Sci TechnolV13, N1, July 1991, P57–68

An analytical study of percussive energy transfer in hydraulic rock drills

An analytical model analyzing stress wave generation and propagation, and percussive energy transfer of hydraulic rock drills is introduced. The model takes into account the local deformation of impact ends of piston and shank adapter. A good agreement between theoretical and experimental results is obtained. The percussive energy transfer of hydraulic rock drills is analyzed with the model. The analysis indicates that the local deformation, when it is within the practical range, does not have a large influence on the efficiency of energy transfer in hydraulic rock drills.