In this paper, the effect of surface curvature on calibration coefficients of the HOLE-DRILLING method has been studied. Firstly, an FE simulation of the DRILLING process has been modeled for a flat surface. Then, the simulation has been implemented on a cylinder with different diameters and the calibration coefficients have been extracted. In all analyses, the stain-gauge rosette and HOLE diameter remain constant and mesh removal in the DRILLING simulation was achieved in eight increments. The comparison of simulation results and standard published calibration coefficients data for a flat surface show an acceptable error equal to 2.8 variation of errors between 0.6 to 6.2.

HOLE cleaning is one of the most important aspects of extractive DRILLING operations. When drill cuttings combine with DRILLING fluids, cutting bed gel is created, which becomes extremely challenging to remove while DRILLING. One of the functions of DRILLING fluid when the flow is static is to maintain the drill bits' suspension. However, the settling of drill bits makes this nearly impossible. In this paper, the influence of fluid viscosity on HOLE cleaning performance was critically studied through a series of laboratory experiments. The effects of different viscosity levels on HOLE cleaning were investigated. This paper evaluated the use of lecithin and carboxymethyl hydroxyethyl cellulose (CMHEC) as a viscosifier and fluid loss agent in oil-based DRILLING fluid. The rheological properties of the formulated DRILLING fluids were determined at various temperatures according to the API 13B-2 specifications in order to identify the most suitable mud type for high-temperature DRILLING operations. From this study, it was discovered that Formulation B has the best rheology, with a plastic viscosity (PV) of 12, 7, and 7 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 30, 24, and 16, respectively. These values were compared with the generic oil-based formulation (A), which had a plastic viscosity (VP) of 43, 39, and 22 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 38, 20, and 26, respectively. The findings show that formulation B has a significant resistance to high temperatures, which means that it can be applied to DRILLING operations in reservoirs with high temperatures. It is more environmentally friendly. Furthermore, this paper explores the implications of the results in terms of the efficiency of HOLE cleaning and the DRILLING process relative to the viscosity of oil-based DRILLING fluid. This paper concludes by providing suggestions for improving DRILLING efficiency through the selection of an appropriate DRILLING fluid viscosity.

This paper proposes the use of a novel electrode containing a modi ed design intended to promote gas-assisted tool rotation-induced debris removal. The proposed tool was observed to be e cient in dispensing the accumulation of eroded materials from the discharge gaps. In this, study the in uence of process parameters like discharge current, tool speed, gas pressure, pulse duration, and duty cycle on output responses is investigated. This outputs responses include: Material Removal Rate (MRR), Electrode Wear Ratio (EWR), and Surface Roughness (SR). A comparative study of the output responses was made with a solid rotary tool and the gas-aided multi-HOLE slotted tool. The outcome revealed that the application of the multi-HOLE slotted tool increased the MRR in Air-Aided Electric Discharge DRILLING (AAEDD) by 40{80%. Besides this, the EWR decreased in AAEDD by 17{25% compared to rotary electric discharge DRILLING (REDD). Moreover, the SR of the AAEDD process was comparatively higher (9{15%) than that of the REDD process. The  ndings showed less surface crack, micropores and recast layers on specimens machined by the AAEDD process in comparison to the REDD process. This study proposes a novel method for improving the machining performance by improving the ushing e ciency of the machining gap to improve the material removal mechanism.

Residual stress is an important parameter which affects the mechanical behavior of manufactured parts. The ASTM standard code E837-01 describes measurement of residual stresses in flat parts using the HOLE-DRILLING method. It presents calibration coefficients for plates with uniform stress distribution. But there is no standard code for measuring residual stresses in curved thin parts using the HOLE-DRILLING method. In this paper, first the calibration coefficients are determined using the FEM for the incremental HOLE-DRILLING method. Then the coefficients are verified using an experimental test and a FE simulation result. The experimental test consists of a flat AA5056F plate under bending conditions. The FE simulation also consists of bending loading condition. In experimental test, calibration coefficients are applied to measure the bending stress using the incremental HOLE-DRILLING method. In FE simulation, strains are determined and used to calculate the induced stress using the calibration coefficients. The results show that the stresses can be determined with good accuracy using the calibration coefficients. Also it is observed that the maximum depth through which the stress distribution can be determined accurately is limited by some factors, such as, stress concentration effects due to the drilled HOLE.

Computational intelligence techniques have a great potential to solve different computational problems in engineering sciences. In this paper, modeling and simulation of down HOLE DRILLING motor using the computational intelligence methods such as artificial neural network (ANN), radial basis function (RBF) and adaptive neuro-fuzzy inference system (ANFIS) is presented. Experimental data are used to train and test the proposed models. The results of the proposed models are compared with the experimental data. The predicated values are found to be in a good agreement with the experimental values. Also, they are very faster than the experimental measurement method. These compact models can reduce the computational time while keeping the accuracy of physics-based model and allow the fast and accurate system level simulation and modeling of industrial packages.Finally, using the proposed ANN model, which is the best proposed model, an equation to describe the nonlinear behavior of down HOLE DRILLING motor is introduced.

Helical milling has been known as an innovative method for making high quality HOLEs. In this method, milling tool generates efficiently a high quality HOLE by moving along a helical path. The HOLE diameter can be adjusted through the diameter of this helical path. Regarding accuracy of HOLE in industrial parts, it is necessary to compare this method with conventional HOLE DRILLING. Therefore, in this study helical milling and conventional DRILLING, have been compared with each other. Eight experiments were conducted considering two levels of cutting speed and feed rate on the samples made of AISI 4340 steel at 45 HRC. Minimum quantity lubricant system with two nozzles was used. 100 ml/h of Behran-11 mineral oil at air pressure of 4 bar was employed in this system. Machining forces, surface roughness, nominal diameter, roundness, and cylindricity were output parameters. According to the obtained results, cutting speed was the only one with positive effect on all qualitative parameters of the machined HOLEs. On the other hand, independency of cutting parameters, helical milling lessened machining forces, surface roughness, and geometrical tolerances in compare with conventional DRILLING.

The study of rotary steering DRILLING technology is currently one of the hot topics in the DRILLING engineering field. It requires accurate well trajectory control instructions when rotary steerable tools are applied to achieve the well trajectory control goal. A DRILLING trajectory prediction model will benefit this progress. According to the continuous beam theory, a mechanical model of push-the-bit rotary steerable bottom HOLE assembly (RSBHA) was established to characterize the bit steering property. The relation of bit lateral force and bit tilt angle with the influencing parameters such as boreHOLE parameters and DRILLING operation parameters was obtained. Then further considering the bit cutting anisotropy, the DRILLING trajectory prediction model was built which quantitatively estimated the variation of inclination and azimuth angle. The model calculation result showed a consistency with the field experimental data proving the prediction model is reasonable in theory and feasible in engineering. This study could provide guidance for selecting the steering parameters to meet the control goal.

Several industrial products such as moulds, dies, engine block, automotive parts, etc., require machining of a large number of HOLEs. Similarly, applications like boiler plates, food-business processing separator's, printed circuit boards, drum and trammel screens, etc., consist of a matrix of a large number of HOLEs. Many machining operations, such as DRILLING, enlargement, tapping, or reaming, are needed to achieve the final sizes of individual HOLEs, resulting in a variety of possible sequences to complete the HOLE-making operations. The major issue involved in HOLE-making operations is the tool travel time. It is often vital to determine the optimal sequence of operations so that the overall processing cost of HOLE-making operations can be minimized. In this work, thus an attempt is made to minimize the total tool travel of HOLE-making operations by using a relatively new optimization algorithm known as modified shuffled frog leaping for the determination of the optimal sequence of operations. Modification is made in the present shuffled frog-leaping algorithm by using three parameters with their positive values in order to widen the search capability of the existing algorithm. This paper considers three case studies of a rectangular matrix of HOLEs to explain the proposed procedure. The outcomes of optimization with a modified shuffled frog-leaping algorithm are compared to those obtained with the genetic algorithm and the ant colony algorithm. Additionally, the higher dimensional problem of 20 x 20 rectangular matrix of HOLEs is considered in this work.

DTH DRILLING is a reliable method for DRILLING in medium to hard geological structures. Considering the country's need for different types of DRILLING bits in various industries, with development of knowledge and production of them, it can limit the vast importation of these products. In this study, process of bit/rock collision taking into account interaction between the insert/body and stresses resulting from interference fit is simulated to determine proper tolerance for fitting, which is the most important factor limiting the life of DRILLING bit. Simulations were carried out taking account rotary motion of bit in addition to impact in single-insert condition with different angles of collision and also in a 3. 5 inch bit with 13 inserts. Mechanical properties of specimens made of DIN1. 6580 steel, used for manufacturing of bit body, were obtained through experiments. Then, in order to validate and also obtain appropriate mesh size, results of pin-hub interference fit simulations with selected parameters were compared to Lame's analytical method. Results show that interference tolerance and speed and angle of impact have great influence on stresses and process forces. In case of 1. 2% of interference, stresses in bit body are about to reach material strength. In the case of 0. 9% and 0. 6%, certain amount of plastic strain is also created in the body. The results of this study is greatly helpful in choosing fitting tolerance of inserts into bit body during manufacturing process.