Papers by Keyword: Bit

Abstract: Abrasive properties of selected rocks and their influence on button bit wear were investigated. Rock samples were obtained from three locations in Southwest, Nigeria. These samples were tested in the laboratory for grain size and circularity factor. Also, porosity, Equivalent Quartz content (EQC), Rock Hardness Number (RHN), Rock Abrasivity Index (RAI) and Uniaxial Compressive Strength were determined. Bit button lengths consumed were measured at regular interval as drilling operation progresses. Results of grain size revealed that medium feldspar granite has least average grain size varying from 0.12 – 0.14 mm. There is possibility that rate of drilling may be low while drilling through this rock. The values of circularity factor varied from 0.624 for medium feldspar granite to 0.786 for coarse muscovite granite. The mean values of porosity varied from between 0.85 and 1.33% for medium feldspar granite and coarse muscovite granite respectively. Biotite hornblende granite has the highest mean uniaxial compressive strength value of 119.48 MPa while coarse muscovite granite has the least mean value of 90.65 MPa. The values of free silica, EQC, RHN, and RAI varied from 35.93 – 51.35%, 45.60 – 67.21%, 575.52 – 821.64 kg/mm³ and 4133.64 – 7003.71 respectively. It was observed that grain size affects the void size in these rocks, which accounted for least porosity value obtained in medium feldspar granite. Average bit button length consumed varied from 15.56 – 24.54 mm for gauge button while length of centre button varied from 13.00 – 19.61 mm. Higher gauge button length consumption could be inferred that it effects the cutting, crushing and wedging of rock mineral components at rock-bit interface. The understanding of grain size, circularity factor and abrasive properties will provide adequate information for quarry to select appropriate bit and drilling machine.

Abstract: The paper deals with hard cutters of drill bits for drilling rocks. The research on geometry of hard alloy and steel cutters of bits that work either under conditions of shockless loads was carried out in this work. The rationale of tungsten carbide and cobalt composition according to their hardness and robustness is provided. Different alloys were suggested to be used for tools working either under conditions of shockless loads or under shock loads for drilling rocks of high hardness. The rock deformation process was identified to occur by cutting and shearing forces. The highest influence on the cutting process is exerted by the acuity angle and back rake angle. Peculiarities of work of cutters with positive, negative and neutral back rake angles were determined as part of the main research. The dependence of penetration depth on the back rake angle of the cutter was obtained. Indicators of wearing identified in the research are including the type and properties of interacting surfaces characterized by the roughness of cutting bit surface, the hardness of materials in contact zone, friction mode that depends on unit pressure, movement rate, the nature of load application, and the rate of interaction of working parts of bit.

Abstract: For the composing and the technical maintenance characteristic of new-type weapon, the BIT information collection technology is developed, and the multi-channel inlayed data acquisition system is established. The implement for equipment technical maintenance can be guided and helped by obtaining equipment technical status information from system, which achieves the science character and pertinence of equipment technical maintenance.

Abstract: Large systems have complex structures and functions, which makes it more difficult in fault isolation. Given the design features of BITs (built-in test) of large complex systems, a method, based on the diagnostic tree and Bayesian network, has been proposed for fault diagnosis and isolation of System-level BITs. First, faults are rapidly isolated in accordance with the diagnostic tree as well as the information of periodic BITs and maintenance BITs. Then, a diagnostic method based on the Bayesian network has been put forward to solve the problems of ambiguity groups of three LRUs or more and to accomplish further diagnosis and isolation. Finally, a certain subsystem of radar has been exemplified to verify the effectiveness of the method proposed by this study.

Abstract: By means of developing new rock abrasiveness device and using quenching steel spiral simulation micro-bit, the experimental investigation on rock abrasiveness that simulating the actual drilling surroundings in petroleum engineering had been conducted. based on the data of micro-bit’s wear weight, which broke unit volume rock, of which experimental samples are made from more than 850 cores of seven main geological profiles in Shengli oilfield, rock abrasiveness is divided into eight grades with Sturges empirical formula. The bit type selection and the bit life prediction could be conducted with the upper experimental method.

Abstract: High pressure is demanded in producting diamond bit by cold-pressing. Although the pressure could be reduced by hot-pressing, a certain pressure is demanded to ensure the compactness of diamond bit matrix. Four sintering parameters, sintering temperature, holding time, sintering pressure and the pressing mode, are mainly included during producting diamond bit by hot-pressing. This article mainly discusses the effect of sintering pressure on the properties of diamond bit. First, select a general formula of diamond bit, take sintering pressure as variable, other parameters remaining immovability; then load and sinter a set of samples in this parameter. Testing and analysing the samples by mechanical properties test, such as bending, tension, compression, and rigidity, and SEM fracture analysis, we obtain the optimum sintering pressure in this formula.

Abstract: In this paper, firstly, the BIT powder was synthesized by ball grinding and the sequent calcinations, starting from TiO2 and Bi2O3. Typically, the grinding technique was facile to form the smaller particles, and the sintering process was utilized to obtain the pure BIT phase. The influence of heated temperature, time and the content of doped rare earth metal (La, Y) on BIT matrix have been investigated in details. The procedure consisted of being pressed, sintered, silver coated to obtain the BIT ferroelectric blocks. Lastly, the BIT density and ferroelectric properties of obtained blocks have been studied. The results showed that via the milling process and the addition of La and Y elements, BIT could be shaped at the lower temperature. Meanwhile, the ferroelectric properties have been improved.

Abstract: Intermittent fault is the main factor for the raise of false alarm during the process of the detection in built-in test (BIT). Two-state Markov model and three-state Markov model for test is built for system fault diagnosis with BIT. According to the application of BIT in some complex system, a comparison of the false alarm rate between two-state Markov model and three-state Markov model is present, which shows we can reduce the false alarm rate (FAR) and improve fault detection rate by using three-state Markov model in BIT.

Abstract: BIT is a new technology about the system test, fault diagnosing and separating. It is more important in the design for the reliability and main tainability of system. The key technique, such as the fault tree and equation, the test location, the test signal picking and generating, the fault distinguish rule, the design of preventing error alarm and BIT software. The result showed that the key technology is useful, and the reliability, maintainability and ability of management to fault can be increased by means of BIT. The debugging of system becomes convenient. The method can be used in the system of intelligent-in-strument and industrial control computer.

Abstract: This study investigated fundamental of phase formation, crystal structure and calcination process for bismuth dysprosium titanate (Bi4-xDyxTi3O12; BDT) powders when x = 0, 0.25, 0.5, 0.75 and 1.0. BDT powders were prepared using a simple solid-state reaction on mixtures of reagent grade Bi2O3, Dy2O3 and TiO2 powders. The mixtures were calcined at temperature in the range of 500-800°C for 4 h at a heating/cooling rate of 5°C/min. Thermal characteristics of powders were studied using thermogravimetric/differential thermal analyses which indicated that the formation of Bi4Ti3O12 and Bi3Dy1Ti3O12 powders occurred at ~500oC. Effect of Dy3+ concentration on phase and crystal structure was investigated using X-ray diffractometry. The results revealed that at small concentration of Dy dopant (x £ 0.25), optimum calcination temperature for providing bismuth titanate-based phase was 650oC. Increasing content of Dy dopant seemed to reduce calcination temperature to 600oC. This study suggested the alternative environmental friendly BDT materials which may be used as starting powders for production of high quality BDT ceramics.